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New Zealand Journal of Geology and Geophysics, 1990, Vol. 33: 89-1090028-8306/90/3301-0089 $2.50/0 © Crown copyright 1990
UMWlM of WAIKATO
E A R T H SCIENCES
R E i RJKT l-'BHARY
3 4 589
A review of late Quaternary silicic and some other tephra formations fromNew Zealand: their stratigraphy, nomenclature, distribution, volume, and age
P. C. FROGGATT
Research School of Earth SciencesVictoria University of WellingtonP. O. Box 600Wellington, New Zealand
D. J. LOWE
Geochronology Research Unit and Department ofEarth Sciences
University of WaikatoPrivate Bag 3105Hamilton, New Zealand
Abstract The stratigraphic relationships and distributionof 36 named late Quaternary (<c. 50000 yr BP.) silicic tephraformations, erupted from 4 volcanic centres—Okataina,Taupo, Maroa, and Tuhua (Mayor Island)—are presented.The stratigraphy and status of several other named lateQuaternary tephras are also discussed. This compilationbrings together all the data, currently scattered through manypublications, to make tephrostratigraphy more accessible andmore easily used. The nomenclature of tephra formations isdiscussed and some rationalisations are suggested. The term"tephrology" is suggested as an appropriate title for the fieldof tephra studies. The deletion of grain-size (ash, lapilli),shape (breccia), and lithologic (pumice) terms from allformation names is recommended, as is standardisation on a"Tephra Formation" format Several tephra layers notpreviously formally named, or without designated typesections, are defined. The dominant ferromagnesian mineralassemblage of each tephra formation has been compiled as anaid to tephra identification. All available radiocarbon ages(384) on each tephra formation are presented, and each age isassessed for reliability in dating the eruption of that tephra.The standard-deviation weighted mean age of the reliableages has been determined as the best current estimate of theage of each tephra. At least 10 tephra formations have noreliable ages, and efforts should be made to date these.
Keywords tephra formation; nomenclature; stratigraphy;mineralogy; C-14 ages; pyroclastics; volume
G89012Received 8 March 1989; accepted 4 October 1989
INTRODUCTION
Quaternary silicic tephras have been studied extensively inNew Zealand for over 50 years, leading to a detailedunderstandingof their stratigraphy, distribution, and processesof eruption. The value of identifiable tephra layers asstratigraphic time-planes has been demonstrated by their rolein a great diversity of Quaternary studies. Our presentknowledge oftephrostratigraphy is due mostly to the dedicatedfield work of two people, C. G. Vucetich and W. A. Pullar,and is embodied in three benchmark papers (Vucetich &Pullar 1964,1969,1973). Recent additions and amendmentsto their framework, largely as a result of better exposures,have resolved finer details of stratigraphic relationships.These refinements are scattered through many publications,and there has been an obvious need to produce a definitivereview of the stratigraphy of the late Quaternary silicictephras. Many radiocarbon ages have been published fordating the tephras, especially recently (Hogg et al. 1987), anda compilation and review of all available ages is provided.
Here, we present a compilation of the interfingeringstratigraphy of tephras erupted since c. 50 000 years ago fromfour silicic volcanic centres, namely Tuhua (Mayor Island),Okataina, Maroa, and Taupo (Fig. 1), with a revision of theformal tephra nomenclature as developed in New Zealand.We have also compiled the history of naming of each layer,references to published isopach maps, estimates of the eruptedvolume, the location of type sections, and all relevantradiometric ages. We present our best estimate of the age oferuption of each tephra. The stratigraphy of andesiu'c tephrasfrom Taranaki and Tongariro Volcanic Centres has beenexcluded as further work on them is in progress.
This review is complementary to that of Lowe (1990)which describes the history of tephra studies in New Zealand.
TEPHRA NOMENCLATURE
Tephra'Tephra" (derived from the Greek tephra ash) is a collectiveterm for all the unconsolidated, primary pyroclastic productsof a volcanic eruption. The term, an ancient one used byAristotle in an account of the eruption on Hiera in the LipariIslands, was reinstated and first defined by the Icelandicvolcanologist, S. Thorarinsson, in his doctoral thesispublishedin 1944 (Thorarinsson 1944,1981). He originally describedtephra as "all the clastic volcanic material which during aneruption is transported from the crater through the air,corresponding to the term lava to signify all the moltenmaterial from the crater" (Thorarinsson 1954, p. 2). The termwas subsequently modified by Thorarinsson (1974), and byHoworth (1975) and Schmid (1981), to include allunconsolidated pyroclastic deposits irrespectiveof their originor nature of emplacement. This broader, morphologicalmeaning is adopted here because it negates the need to
90 New Zealand Journal of Geology and Geophysics, 1990, Vol. 33
175°E
NORTH ISLANDNEW ZEALAND
- 38°S
km
Fig. 1 The central North Island of New Zealand with the volcaniccentres from which late Quaternary silicic tephras have been erupted(adapted from Cole 1979 and Wilson etal. 1984). Okataina VolcanicCentre is subdivided into two parts: Haroharo (H) to the north andTarawera (T) to the south. W, White Island; To, MtTongariro; N, MtNgauruhoe; R, Mt Ruapehu. Wilson et al. (1986) postulated theexistence of "Whakamaru caldera" in the northern Taupo - Maroaarea in addition to those shown here.
distinguish pyroclastic flow deposits from airfall deposits,and it encompasses primary pyroclastic deposits generated oremplaced subaqueously or subglacially. Thorarinsson (1974)noted that this usage complements rather than replaces termssuch as ignimbrite and welded tuff.
We emphasise that "tephra" denotes essentiallyunconsolidated material, thus welded(or hardened) pyroclasticmaterials, of either flow or airfall origin, should not normallybe described as "tephra". It is also our intention that uncon-solidated pyroclastic deposits that originate from explosionsresulting from the interaction of lava with either groundwater(e.g., forming pseudocraters: Thorarinsson 1979) or seawater(e.g., forming littoral cones: Fisher 1968), and thus originatingfrom rootless vents, may be described as tephra.
The adjective "pyroclastic" (Greek pur fire, klastosbroken in pieces), a collective term for clastic or fragmentarymaterials ejected from a volcanic vent (Fisher & Schmincke1984), is a more comprehensive term man tephra and is notnecessarily synonymous with i t
The stratigraphic entity composed of tephra is oftenloosely referred to in New Zealand as a"tephra" or collectivelyas "tephras", but "tephra layer" or "tephra bed" is etymologi-cally more correct and this use is encouraged here. Although
tephra as a collective noun may be singular or plural, weconsider it sensible that an "s" should be appended to form theplural if it avoids ambiguity. In the derivative terms"tephrostratigraphy" and "tephrochronology" the "a" isreplaced with an "o".
Although "tephra" is deliberately defined as a nongeneticterm, it has often been found useful to distinguish betweenthree (or more) fundamentally different mechanisms oftransport and emplacement of tephra: airfall, pyroclasticflow, and surge. The last term is usually distinguished fromfall or flow processes (Wright et al. 1980). Vucetich & Pullar(1973) suggested"fall-tephra" and"flow-tephra"butalthoughthese terms were adoptedby some workers they have not beenwidely used. The genetic term "ignimbrite" (see below)adequately suits the products of a pyroclastic flow (e.g.,Sparks etal. 1973; Sparks & Walker 1977; Froggatt 1981d),but there is no equivalent word for the airfall phase. "Pliniantephra" or "Plinian pumice" (Walker 1980) may be appropriatein a volcanological sense, but are here regarded as being toospecific genetically as stratigraphic terms, requiring theestablishment that the eruption was truly Plinian in nature.These terms are then applicable only to tephra from Plinianeruptions and exclude other mechanisms such asphreatomagmatic. The term "airfall tephra" or perhaps "fall-tephra" or "fallout tephra" are probably still the mostappropriate where an indication of genesis is required.
The adjective "tephric" (meaning related to, or of, tephra)has been applied informally to various deposits derived fromtephra by reworking or chemical weathering. There isconsiderable merit in a term that denotes the origin or majorconstituent of a strongly weathered or secondary deposit, andwe find "tephric" preferable to the use of "tephra" for materialnot of primary origin.
The use of "tephra" for epiclastic sediments dominatedby volcanic detritus (e.g., Seward 1976) is not consistent withthe definition of tephra as primary volcanic material.Rationalisation of the nomenclature of these types of deposits(Schmid 1981) recommends the use of "tuff* for friabledeposits, and tuffaceous sandstone or siltstone for lithifieddeposits; we suggest that "tephric" (e.g., "tephric sand" or"tephric alluvium") could also be applied to unconsolidatedsediments of the sort described by Seward (1976).
Ignimbrite
"Ignimbrite" (Marshall 1932,1935) is a genetic term for theprimary depositofapyroclasticflow or flows. The etymologyof the term is uncertain (Froggatt 1984) but is probably fromthe Latin ignis (fire) and imbrex -imbris (stormcloud), ratherthan nimbus (cloud) which does not contain an "r". Asignimbrite has two common lithological states it is usuallyconvenient to qualify the term with welded or unwelded asappropriate. Welding involves the adhering together of hot,glassy fragments under the influence of a compactionallithostatic load (Cas & Wright 1987). Some ignimbrites,typically known as sillar, may be hardened by vapour phasecrystallisation and, although having the appearance of beingwelded,arebetterdescribed as cemented (Fisher & Schmincke1984; Cas & Wright 1987).
Tephra formationThe need for the formal definition of a stratigraphic layer oftephra as a "formation" was argued by Gregg (1961), whoalso recommended the use of "tephra formation". Formation
Froggatt & Lowe—L. Quat, tephra formations, N.Z. 91
naming was adopted by Vucetich&Pullar(1964,1969,1973)and adapted to "tephra formation" by Howorth (1975). Theproducts of one eruption sequence may contain coarse, well-sorted airfall pumice, thick unsorted ignimbrite, surge deposits,and distal, thin, fine ash layers. On the scale of a regionalgeological map such lithological variations may be minor andencompassed by a single formation, but at the millimetrescale of detailed tephrostratigraphical or volcanological studiesthey are important. By definition, a "tephra formation" isstrictly neither a chronostratigraphic nor lithostratigraphicterm as defined by the International Stratigraphic Guide(Hedberg 1976), but contains elements of both (Gage 1977).It could be classed as an allostratigraphic unit under therevised North American Code (North American Commission1985). The base of a tephra formation is essentially anisochronous plane and is of fundamental importance in tephrastratigraphy. The top of a formation may be time transgressive,and may have additions of material from other sources (e.g.,loess, andesiu'c tephra), and is of less importance in astratigraphic sense. For rhyoliu'c tephra layers, a tephraformation contains all the primary pyroclastic products of oneeruptive episode, each separated by significant time intervalsthat are often marked by paleosols. It may be divided intonamed members where appropriate. Andesitic tephraformations in New Zealand have commonly been defined toinclude the products of more than one eruption and hence mayspan a considerable time period as a consequence of the moreintermittent eruptive nature of these types of volcanoes (e.g.,Neall 1972; Topping 1973).
Formations composed of tephra, as defined above, are aspecial type of formation, but their naming should conform tothe accepted stratigraphic guide. A formation name should becomposed of geographical and lithological components, andwe would argue that tephra is the most appropriate lithologicalterm for these formations. This also emphasises their uniquenature, particularly as isochronous stratigraphic markerbeds, and distinguishes them from other lithologicalformations.
Volcanic formation and eruptive episodeCole (1970a) mapped lavas and pyroclastic deposits (tephra)erupted from Tarawera and demonstrated their coeval nature.He grouped both types of deposits into "volcanic formations".Nairn (1980,1981,1986) has mapped coeval lava and tephrain Haroharo caldera as separate formations, but has indicatedthe close time and genetic links between the tephra and thelava by grouping both into an informal "eruptive episode".Such an eruptive episode (e.g., Kaharoa eruptive episode)consists of all the primary volcanic material produced duringa relatively short-lived eruption sequence.
Ash, lapilli, and breccia in formation namesThe original formal definitions of many late Quaternarytephra layers (Baumgart 1954; Baumgart & Healy 1956;Vucetich & Pullar 1964, 1969) included a grain-size termdenoting the dominant or most frequently observed grain size(for instance Kaharoa Ash, Taupo Lapilli), or the dominantgrain shape or texture (Oruanui Breccia, Rotoiti Breccia).Since the definition of these, the term "tephra" has gainedwidespread acceptance and has been incorporated bypreference into formation names (e.g., Howorth 1975;Vucetich & Howorth 1976b; Hogg & McCraw 1983). Generalconsensus, together with the continuing use of "tephra",
suggests that most of these grain-size and clast shape ortextural terms are not appropriate and should be replaced.However, the names of members of formations may contain agrain-size or lithological term if the member is dominantly ofthis grade or lithology. Such names also serve to distinguishthe member status of the deposits from that of formations(denoted by "Tephra").
The opportunity has been taken to rename some tephralayers when recently redefined (e.g., Hinemaiaia TephraFormation: Froggatt 1981c). We propose here to formallyrename those formations with an "Ash" suffix as 'TephraFormation" and those members with a "Breccia" suffix as"Ignimbrite" where appropriate. We also propose to renameTaupo Pumice Formation as Taupo TephraFormation, becausesome members of the formation are not pumiceous (e.g.,Rotongaio Ash). Our redefined names are listed in Table 1.Other new names are defined below.
TephrologyNo single term adequately describes the scientific disciplinecurrently informally called "tephra studies" (e.g., Self &Sparks 1981). "Tephrostratigraphy" and"tephrochronology",as specialist subjects within "tephra studies", are unsuitable.Consequently, we suggest that "tephrology" (Greek tephraash, logos discourse or subject of study) may be an appropriateterm for the science of "tephra studies", which includes thestratigraphy, chronology, correlation, and petrology of tephralayers.
VOLCANIC CENTRES ANDTEPHROSTRATIGRAPHY
The central North Island has had silicic eruptive activity sinceat least the early Quaternary, but the sites of volcanism havevaried with time. A broad, wedge-shaped zone containing allQuaternary volcanism was defined as the Central VolcanicRegion (CVR) by Thompson (1964). A narrower zone ofpresently orrecently active volcanoes is Taupo Volcanic Zone(TVZ) (Healy 1961), and volcanoes within this zone wereplaced in "volcanic centres" (see below).
Subsequently, Rogan (1982) and Wilson et al. (1984)inferred a sixth centre, south of Rotorua, mostly fromgeophysical evidence, which they named Kapenga VolcanicCentre. However, the activity of this centre and its relationshipto Okataina is unclear. Whether any of the late Quaternaryeruptives considered here have originated from Kapenga hasnot been definitively stated, but Earthquake Flat TephraFormation is a likely candidate, although it has closechronological associations with Rotoiti Tephra Formationfrom Okataina (I. A. Nairn pers. comm. 1988).
We have included the widespread silicic tephra fromMayor Island (Tuhua Tephra) in this review, so we herepropose a seventh centre: Tuhua Volcanic Centre, from theMaori name for the island. This centre encompasses all theeruptive vents on the pantelleritic Mayor Island volcanicedifice. Buck et al. (1981) classified all the lavas on the islandas Tutaretare Rhyolite Formation and all pyroclastic depositsontheislandastheOiraPyroclastiteFormation.bothformationsconstituting the Mayor Island Group. Houghton et al. (1985)named the Ruru Pass Tephra on the island without defining itsstratigraphic status, but the stratigraphy of this and othereruptives on the island is currently under review (Houghton &Wilson 1986; B. F. Houghton pers. comm. 1988).
92 New Zealand Journal of Geology and Geophysics, 1990, Vol. 33
Table 1 The formal stratigraphic name of each tephra formation and members, as proposed here, followed by the abbreviation used forthe tephra; references to where the name was first defined or modified; references to isopach maps; the location of the type section (gridreferences based on the national 1:50 000 map series); the error-weighted mean age and pooled enor (old hah' life basis), and the numberof ages (N) in the mean, based on the data in Appendix 1. Provisional estimated ages (italics) are given where no dates are available, or wheredates are uncertain. The tephra formations derived from each volcanic centre are listed in stratigraphic order.
Formation and members
Okataina Volcanic CentreTarawera Tephra
Rotomahana MudTarawera Scoria
Kaharoa TephraRotokawau Tephra*Whakatane TephraMamaku TephraRotoma TephraWaiohau TephraRotoma TephraRerewhakaaitu TephraOkareka TephraTeRere TephraOmataroa TephraAwaken TephraMangaone TephraHauparu TephraTeMahoe TephraMaketu TephraTahuna TephraNgamotu TephraEarthquake Flat Tephraf
Rifle Range Ash*Earthquake Flat Ig.
Rotoili TephraRotoehu AshRotoiti IgnimbriteMatahi Scoria
Taupo Volcanic CentreTaupo Tephra
Taupo IgnimbriteTaupo LapilliRotongaio AshHatepe AshHatepe Lapilli
Mapara TephraWhakaipo TephraWaimihia Tephra
Waimihia IgnimbriteWaiminia Lapilli
Hinemaiaia TephraMotutere TephraOpepe TephraPoronui TephraKarapiti TephraKawakawa Tephra
Oruanui IgnimbriteAokautere Ash
Poihipi TephraOkaia TephraTihoi TephraWaihora TephraOtake Tephra
Maroa Volcanic CentrePuketarata Tephra
Tuhua Volcanic Centre*}:Tuhua TephraUnnamed tephra
Symbol
TrTrmTisKaRwWkMaRmWhRrRkOkTeOmAwMnHuTmMkTaNt
RaEa
ReRbMb
TpTpiTlRnHuHtlMpWoWmWmiWmlHmMtOpPoKpKkOuAoPOTiWOe
Pk
Tu
Ref 1
131345,13,3213,3227,3213,32323213,22,32323333161633,161616161616
2338,39,23
33,4239,4225
1,14,913,911913434143918,34,18834347,343033,39,116,303131313131
17,34
15,2120
Ref 2
2424,32,28,5,4024,32,26,532224,3224,32,2024,32,2024,32,2024,32^024,32,2024,33331616161616161616
##
24,33,19,41##
24,26321,32,351,37,32,4437,321,32,363434,2024,32
1,24,32,34,368,34,18834,20347,10,344,24,33,29,43,446,12#3131##
17
15,20#
Type section
VI6/128206*VI6/185257*V16/174198*b
U15/054336V17/322989U16/945315VI6/141154VI6/141150U16/018316VI6/141150U16/065306V16/252179V15/351361V16/351361V15/368461V15/396548V15/396548V15/396548VI6/410256VI6/410256
Ul 6/833119*U167955279*
W15/623519U15/051631V16/355390*
Ul 8/798728U18/792617C
Ul 8/798728Ul 8/798728Ul 8/798728Ul 8/798728Ul 8/798728Ul 8/798728Ul 8/899574*Ul 8/899574Ul 8/899574Ul 8/743531Ul 8/743531Ul 8/798728U18/839535Ul 8/798728T17/619830T17/619830T24/343877T17/658890T17/619830T17/575881T17/678866T17/678866
U17/753902
T12/636403
Age
1886AD
770 ±203440 ±704830 ±207250 ±208530 ±1011850±6013 080 ±5014 700 ±110c. 1800021100 ±32028 220 ±630c. 29 00027730±350d
35 870±1270c. 39 000c. 41 000c. 43 000c. 45 000c. 50 000
c. 50 000
1850±10
2160 ±252685 ±203280 ±20
4510 ±205430 ±609050 ±409810 ±509820 ±8022 590 ±230
c. 23 000c. 23 500c. 46 000c. 47000c. 48 000
c.14 000
6130 ±30c.14 500
N
15121224512103
23
102
41
61317
12310344§
10
References1
23
4
56
78
910111213141516
17
181920
21222324
252627282930
3132
333435363738394041424344
Baumgart 1954
Beanland 1981,1982Berry 1928
Campbell 1986Cole 1970aCowie 1964
Froggatt 1981bFroggatt1981c
Froggatt 1981dFroggatt & Soloway 1986Froggatt et al. 1988Gcddesetal. 1981Grange 1929,1937Healy 1964bHogg & McCraw 1983Howorth 1975
Lloyd 1972Lowe 1986
Lowe 1987Lowe 1988aLowe et al. 1980Nairn 1980Nairn & Kohn 1973
Pullar&BirreU1973a,bPullar& Nairn 1972Pullaretal. 1977Taylor 1953Thomas 1888Self 1983Vucetich & Howorth 1976a
Vucetich & Howorth 1976bVucetich &Pullar 1964
Vucetich & Pullar 1969Vucetich & Pullar 1973Walker 1980Walker 1981aWalker 1981bGrindley 1959,1960Healy etal. 1964 .Walker etal. 1984Walker 1979Nairn 1972
Self & Healy 1987Self & Sparks 1978
* Defined here# No isopach map publishedt May derive from Kapenga Volcanic Centre (see text)i Tephra layers occuring on mainland North Islanda Strictly outside Okataina Volcanic Centre—hypostratotype (reference section) defined at
U15/071442 (Beanland 1981,1982)b Hypostratotype defined at V16/175197c Hypostratotype defined at U15/799535Ref 1 References where first named or formally defined or redefinedRef2 References where isopach maps published§ Mean of the 4 charcoal dates in Wilson et al. (1988). Pooled mean of all 16 dates is 20 685±100 yr
d See text
Froggatt & Lowe—L. QuaL tephra foimations, N.Z. 93
At the northern end of TVZ, a group of andesitic torhyolitic eruptives, including White and Whale Islands, MtEdgecumbe, and Manawahe, exhibit close affinities to oneanother and were informally grouped into the "Bay of Plentyvolcanic centre" by Duncan (1970). Insufficient is currentlyknown about these volcanoes and (heir relationships to otherareas to justify formalising this term.
Named volcanic centres and the standard abbreviationswe propose are shown in Table 2. Cole (1979) and Wilson etal. (1984) have presented the location and extent of eachcentre, and Fig. 1 is based on their maps.
The post-50 000 year tephra formations erupted from eachcentre are listed in Table 1. There are no known eruptivesfrom Mangakino in this time range (Wilson et al. 1984).Those from Okataina can be further subdivided according tothe site of eruption. Tarawera, Kaharoa, Waiohau,Rerewhakaaitu, and Okareka Tephras are from Tarawera(Vucetich & Pullar 1964; Cole 1970a); the remainder arefrom the Haroharo complex (Nairn 1981,1986) to the north.
Detailed mapping of individual tephra layers, supple-mented by distal stratigraphic and chronological studies(Vucetich & Pullar 1964,1969,1973; Vucetich & Howorth1976a, b; Howorth 1975; Howorth & Topping 1979; Froggatt1981a, c; Froggatt & Solloway 1986; Lowe 1986,1988a, b)has enabled the interbedded stratigraphy of 38 formationsfrom the 4 silicic volcanic centres to be elucidated (Fig. 2).
HIERARCHY OF STRATIGRAPHIC NAMES
The definition of a tephra formation allows for theestablishment of members within that formation. With mosttephra formations this is unnecessary, but five formations(Taupo Tephra, Waimihia Tephra, Kawakawa Tephra, RotoitiTephra, and Earthquake Flat Tephra) have such widespreador distinctive units that definition of members has been founduseful. This is especially the case for formations with bothairfall and ignimbrite components. Other formations mayeventually be subdivided where necessary.
At a broader level, a stratigraphic term encompassingseveral tephra formations has value. Healy (1964b) proposedan Arawa Group comprising Taupo Subgroup and RotoruaSubgroup (Vucetich & Pullar 1964). This subdivision has notfound widespread favour, perhaps being too general forpractical use. A useful amalgamation into four subgroups(Fig. 3) delineated by the widespread formations at c. 22 500and c. 50 000 years ago was proposed by Howorth (1981) andwe recommend adoption of this proposal. Formations withineach group are shown in Fig. 2. All the formations derivedfrom one eruptive centre (e.g., Okataina, Taupo) are deemedto constitute a group. For example, the Lake Taupo Group
Table 2 Named volcanic centres, the standard abbreviations wepropose, and the authors of the names.
Volcanic centre
Tuhua Volcanic CentreRotorua Volcanic CentreOkataina Volcanic CentreKapenga Volcanic CentreMaroa Volcanic CentreTaupo Volcanic CentreMangakino Volcanic CentreTongariro Volcanic Centre
Abbreviation
(TuVC)(RVC)(OVC)(KVC)(MVC)(TVC)(MkVC)(TgVC)
Reference
(this paper)(Cole 1970b)(Healy 1962)(Rogan 1982)(Healy 1962)(Healy 1964a)(Wilson etal. 1984)(Healy 1964a)
presently comprises Taupo Subgroup, Kawakawa TephraFormation, and Okaia Subgroup; the Okataina Groupcomprises Rotorua Subgroup, Mangaone Subgroup, andRotoiti Tephra Formation.
DEFINITIONS OF NEW NAMES
1. Taupo Tephra Formation comprising Taupo Ignimbrite,Taupo Lapilli, Rotongaio Ash, Hatepe Ash, and HatepeLapilli membersTaupo Pumice Formation and some members were namedby Grange (1931), but formalised by Baumgart (1954)with the type section at the "Terraces pumicepit". Furthermembers were named by Healy (1964b) and Froggatt(1981d). We consider "pumice" inappropriate for use asa name for a formation of such diverse character and grainsize, so we propose Taupo TephraFormation, as suggestedby Froggatt (1979). The member names and their strati-graphic relationships are shown in Fig. 2.
2. Waimihia Tephra Formation comprising WaimihiaLapilli and Waimihia Ignimbrite membersWaimihia Lapilli is a widespread airfall tephra layer,composed of coarse pumice lapilli in the Taupo area, andwas first named by Baumgart (1954). Healy (1964b)recognised the multiple nature of the eruption andproposedWaimihia Formation with Waimihia Lapilli as a member.Vucetich & Pullar (1964) recognised the presence of atypically thin fine ash unit above the lapilli, and they refer-red to the two units as Wm 1 and Wm2, respectively. Later,Vucetich & Pullar (1973) recognised the upper ash unit(Wml) as part of an unwelded ignimbrite of restricteddistribution and included it within their WaimihiaFormation.
We propose the establishment of Waimihia TephraFormation, composed of two members: a lower WaimihiaLapilli (Wml) and an upper Waimihia Ignimbrite (Wmi).The type section and type area for "Waimihia Formation"were defined by Healy (1964b) at Iwitahi, east of Taupo.Vucetich & Pullar (1973) designated the DeBretts section,Taupo, as a reference section because the Iwitahi sectionhad been partly destroyed. Within the type area nearIwitahi, a section at Mere Rd (U18/899574*) is suggestedas a new type (neostratotype). An additional referencesection for Waimihia Ignimbrite is proposed on StateHighway 1 at Hatepe Hill (U18/735567).
Waimihia Lapilli is characterised by grey-bandedpumice, oxidised lithic clasts, and rare basaltic clasts inthe upper half of the deposit None of these types of clastsappear to be present in the overlying ignimbrite unit.
3. Kawakawa Tephra Formation comprising OruanuiIgnimbrite and Aokautere Ash membersThe ongoing nomenclature difficulties of the c. 22 500yearolderuptiveproductsfromTauporequireclarification.These products were originally named OruanuiFormation,comprising Oruanui Ash and Oruanui Breccia (Vucetich& Pullar 1969). The recognition of miscorrelations, andthe inclusion of an older unit (Okaia Tephra) at the base,
*Grid references are based on the metric 1:50 000 topographicalmap series NZMS 260.
94 New Zealand Journal of Geology and Geophysics, 1990, Vol. 33
0 -
2 -
4 -
6
8 -
10-
12-
14
16-
18 -
2 0 -
CLCD 2 2 -
(0 2 4 -
O 26-O
a>2 8 -
3 0 -
3 2 -
3 4 -
3 6 -
3 8 -
4 0 -
4 2 -
4 4 -
4 6 - -
4 8 - -
OKATAINA
-Kaharoa Tephra
VOLCANIC CENTRETAUPO MAROA TUHUA
Taupo TephraMapara Tephr
-Whakatane Tephra
-Mamaku Tephra
• Rotoma Tephra
Taupo Teph-Mapara Tep—Whakaipo T
Waimihia Te
rahra
p ephraWaimihia Tephra.
Hinemaiaia Tephi
Motutere Tephra
Taupo IgnimbriteTaupo LapilliRotongaio AshHatepe Ash
. Hatepe Lapilli
,rXfWaimihilra \Waimihi
Waimihia Ignimbrite^Waimihia Lapilli )
T_ • Opepe Tephra. Poronui Tephra' Karapiti Tephra
-Waiohau Tephra
-Rotorua Tephra
• Rerewhakaaitu Tephra
- Okareka Tephra
— Te Rere Tephra
- , LKawakawa Tephra -
Poihipi TephraOkaia Tephra
Omataroa Tephra• Awakeri Tephra
— — Mangaone Tephra
Hauparu Tephra
-Te Mahoe Tephra
Maketu Tephra
Tahuna Tephra
Ngamotu Tephra
Tihoi Tephra
• Waihora Tephra
Otake Tephra
-Tuhua Tephra
• Puketarata Tephra
fOruanui IgnimbriteI Aokautere Ash
nimbrite')Ash J
— • Earthquake Flat Tephra •
5 0 - t = = = = —Roto i t i Tephra- Rotoehu AshRotoiti IgnimbriteMatahi Scoria
/ Rifle Range Ash\Earthquake Flat Ignimbrite
Fig. 2 The stratigraphic relationships of the named late Quaternary silicic tephras in time and space, showing the interfingering of tephrasfrom four volcanic centres and the grouping of some into four subgroups (Taupo, Okaia, Rotorua, and Mangaone). Solid tie lines to thechronology scale are based on mean conventional radiocarbon ages from Table 1 and Appendix 1. Dashed lines indicate no date is available;a relative chronology is suggested from stratigraphic relationships and the degree of paleosol development on undated tephras. The age ofc. 50 000 years given for the oldest formation (Rotoiti) is assumed, as discussed in the text.
Froggatt & Lowe—L. Quat tephra formations, N.Z. 95
OKATAINA GROUP
ROTORUA SUBGROUP
LAKE TAUPO GROUP
TAUPO SUBGROUP
KAWAKAWA TEPHRA FORMATION
MANGAONE SUBGROUP OKAIA SUBGROUP
ROTOITI TEPHRA FORMATION
Fig. 3 The hierarchy of group and subgroup names for lateQuaternary silicic tephra deposits as proposed by Howorth (1981).The zig-zag line separating the subgroups indicates the spatial andstratigraphic interfingering of the tephra formations. The individualformations within each subgroup are shown in Fig. 2.
led Vucetich & Howorth (1976a) to the definition ofKawakawa Tephra Formation containing three members:Aokautere Ash, Scinde Island Ash, and Oruanui Breccia.Oruanui Breccia was defined by Vucetich & Pullar (1969),Scinde Island Ash was named by Berry (1928) for a layerof ash found at Napier and containing in part accretionarylapilli (for which he coined the term "chalazoidites"), andAokautere Ash was defined by Cowie (1964) as a beddedunit of fine and coarse white ash, without appreciableaccretionary lapilli, at Aokautere, near Palmerston North.Vucetich & Howorth (1976a) correlated parts of the twodistinctively different distal ash layers with near-sourcelayers of similar character at the type section onWhangamata Road, and argued that the original namesshould become member names.
An unwelded ignimbrite, described from drill cores atWairakei, was named Wairakei Breccia by Grindley(1965). Vucetich & Pullar (1969), in naming OruanuiBreccia, recognised its similarity of stratigraphic positionand appearance to Wairakei Breccia. Correlation betweenthe two is now widely accepted (e.g., Self 1983; Wilson1988). In a detailed volcanological study of the c. 22 500yr B.P. deposits, Self (1983) referred informally to thewhole formation as the Wairakei formation, and has morerecently argued for its formalisation (Self & Healy 1987).The term Wairakei is probably invalid for both WairakeiBreccia and Wairakei Formation (Froggatt et al. 1988),having been previously applied to Wairakei Ignimbrite(Beck & Robertson 1955). Wilson (1988) has proposedthat Oruanui Formation should be reinstated as the soleformation name, but it, too, has prior usage.
We propose to retain Kawakawa Tephra Formation,asdefinedbyVucetich&Howorth(1976a)atthe Whanga-mata Road type section (T17/619830). We have renamedOruanui Breccia as Oruanui Ignimbrite, and propose thatAokautere Ash as defined by Cowie (1964) be used for allthe airfall ash within Kawakawa Tephra Formation,including the lower airfall beds at the Kawakawa Tephratype section on WhangamataRoad. This usage is analogousto Rotoehu Ash within Rotoiti Tephra Formation.
Oruanui Ignimbrite is invariably overlain by an erosionsurface, in turn overlain by Mokai Sand (Vucetich &
Pullar 1969). Mokai Sand is a sequence of aeolian depositsderived from Kawakawa Tephra, which range from coarsewell-bedded pumice sands to fine tephric dunes withmassive to fine, undulose bedding.
4. Earthquake Flat Tephra Formation comprisingEarthquake Flat Ignimbrite and Rifle Range AshmembersEarthquake Flat Breccia Formation has been describedand mapped by Grindley (I960), Healy et al. (1964), andNairn & Kohn (1973). It consists of unwelded, crystal-rich pyroclastic flow units with interbedded and mantlingbiotite-rich airfall tephra units. It was erupted fromexplosion craters centred on Earthquake Flat to the southof Rotorua. Nairn & Kohn (1973) demonstrated that theEarthquake Flat eruptions immediately followed those ofthe Rotoiti Tephra Formation (see below), and thusascribed them the same age. The widespread, biotite-rich,pinkish-grey airfall tephra units were informally named"Rifle Range ash" by Nairn & Kohn (1973).
In line with our proposals for nomenclature of theRotoiti tephra deposits, we propose that the EarthquakeFlatBrecciaFormationberenamedEarthquakeFlatTephraFormation, and comprise two members: Earthquake FlatIgnimbrite for the pyroclastic flow deposits and RifleRange Ash for the intercalated and mantling airfall tephradeposits. Type sections have not previously beendesignated for these units so we propose the referencesections described in Nairn & Kohn (1973, p. 272) onState Highway 5, 4 km south of Hemo Gorge (U16/955279) for Earthquake Flat Ignimbrite, and at MalemeRoad (p. 274) (U16/833119) for Rifle Range Ash.
5. Rotoiti Tephra Formation comprising Matahi Scoria,Rotoehu Ash, and Rotoiti Ignimbrite membersThe widespread pyroclastic unit from Okataina, with anestimated age of c. 50 000 years or more (see Chronologysection below), has an initial basaltic airfall phase(Matahi Basaltic Tephra: Pullar & Nairn 1972), arhyoliticairfall phase (Rotoehu Ash), and an unwelded ignimbrite(Rotoiti Breccia), which were all grouped under RotoitiBreccia Formation by Vucetich & Pullar (1969). Therelationships between the tworhyoliticphasesarecomplexwith the airfall ash found both beneath, and interbeddedwithin, the ignimbrite (Nairn 1972; Walker 1979). Weconsider the term "Rotoiti BrecciaFormation" as inappro-priate for such a diverse formation, not withstanding theundesirability of a grain-shape term. Rotoiti TephraFormation is here proposed, comprising three members:Matahi Scoria, Rotoehu Ash, and Rotoiti Ignimbrite.
TYPE SECTIONS
To formally define a formation, a single outcrop or sectionmust be designated the type section (holotype), and should besupported by a type area and perhaps reference sections(Hedberg 1976). Many of the current names of tephraformations originated before formal stratigraphic nomen-clature was formulated. Some formation names have not beenformalised and still do not have type sections.
Type sections for all formations, including those newlyproposed, are compiled in Table 1. The 10 new sectionsdefined here (Table 3) are based on previously described
96 New Zealand Journal of Geology and Geophysics, 1990, Vol. 33
stratigraphic sections. In addition, anew reference section forTaupo Tephra Formation in support of the type (hypostrato-type: Hedberg 1976) is defined on State Highway 1 south ofTaupo atU15/799535.SimUarlyahyrx)stratotypefor KaharoaTephraFormation is defined on Crater Road near MtTaraweraatV16/175197.
OTHER NAMED LATE QUATERNARY TEPHRADEPOSITS
In addition to the tephra formations listed in Table 1, severalother late Quaternary tephra layers, other than those fromTongariro and Taranaki, have been named. Four of these arebasalts, and although limited in distribution, have stratigraphicvalue where found. Other named tephra layers have proved tobe correlatives of known tephra formations and the status ofthese names is discussed here.
Basaltic tephras(1) Tarawera Tephra Formation
The material erupted from Tarawera on lOJune 1886 was firstnamed Tarawera Ash and Lapilli by Grange (1929, 1931,1937) for the coarse basaltic tephra, and Rotomahana Mud(Grange 1929; Nairn 1979; Walker et al. 1984) for the phre-atic ash. The former unit was renamed Tarawera Basalt (Cole1970a) as a member of his Tarawera Formation. We proposea Tarawera Tephra Formation comprising Tarawera Scoria(Trs) (to replace both Tarawera Ash and Lapilli and TaraweraBasalt) and Rotomahana Mud (Trm) members. The termTarawera Tephra was first proposed by Gregg (1961).
Neither of the members of Tarawera Tephra Formationhave been designated type sections. For Tarawera Scoria, wepropose the adoption of the section through the southeast wallof the Tarawera Crater (Chasm) opposite Wahanga dome(V16/185257) as the type section. This corresponds to thesection described at "Reference site A" by Walker et al.(1984, p. 64), and is near to that described by Cole (1970a,p. 100). The type area is designated as the entire chasm on MtTarawera. Proximal deposits of Rotomahana Mud are wellexposed in cliffs around the shore of Lake Rotomahana, andwe propose the type section to be at V16/128206, a lakeshorecliff section described at "Reference site A" by Nairn (1979,p. 366). The type area extends in a circle of 3 km radiuscentred on the type section.
Table 3 The locations of the 10 newly defined type sections.Detailed section descriptions have been published in die referencescited.
Tephra Formation
Tarawera TephraRotomahana MudTarawera Scoria
Rangitoto TephraKaharoa TephraWaimihia TephraRotokawau TephraOhakune Tephra
Earthquake Flat TephraRifle Range AshEarthquake Flat Ig.
Rotoiti TephraMatahi Scoria
*(NZMS 260 grid ref.).
Type sectionlocation*
V16/128206V16/185257
R10/808928V16/174198Ul 8/798728U15/053436S20/176974
U16/833119U16/955279
V16/355390
Reference
Nairn (1979)Walker etal. (1984)
Brothers & Golson (1959)Cole (1970a)
Vucetich & Pullar (1964)Houghton & Hackett (1984)
Nairn & Kohn (1973)Nairn &Kohn (1973)
Pullar & Nairn (1972)
(2) Rotokawau Tephra FormationA basaltic airfall tephra, originally named Rotokawau Ash,lies between Whakatane and Kaharoa Tephra (Vucetich &Pullar 1964) and was erupted from a line of craters northeastof Rotorua(Beanland 1981,1982). It is immediately overlainby a Taupo-derived tephra at Holdens Bay (Kennedy et al.1978), either Whakaipo or Waimihia Tephra (Green 1987). Asingle reliable radiocarbon age on the formation is 3440 ± 70yr B.P. (NZ7356: N. M. Kennedy pers. comm. 1988). Otherages are given in Appendix 1. We propose to rationalise thename to Rotokawau Tephra Formation, and suggest thatthe reference section of Beanland (1981) at U15/071442 isadopted as a hypostratotype in support of the section given inVucetich & Pullar (1964).
(3) Matahi Scoria
The basal member of Rotoiti Tephra Formation, named byPullar & Nairn (1972), is a basaltic airfall tephra of limitedthickness and distribution. We propose altering the name toMatahi Scoria. A type section was not designated so wepropose that the reference section at V16/355390 (=N77/161093 of Pullar & Nairn 1972, p. 448) becomes the typesection.
(4) Rangitoto Tephra Formation
Rangitoto Tephra was erupted from Rangitoto Island(Auckland) around 750 years ago (NZ220, 750 ± 50 andNZ222,770 ± 50 yr B .P.; Grant-Taylor & Rafter 1963). It wasinformally named Rangitoto Ash by Taylor (1953) and laterdescribed by Brothers & Golson (1959). We propose theformal definition of the tephra as Rangitoto TephraFormation (Ro)with the type at the section at "Pig Bay" (inAdministration Bay) on Motutapu Island (RIO/808928) asdescribed by Brothers & Golson (1959, p. 570).
Ohakune Tephra FormationA tephra layer of limited areal extent originated from cratersnear Ohakune (Houghton & Hackett 1984). Near-ventexposures of tuff-ring-forming tephra are found in severallarge quarries, with distal material in several road exposures.The tephra is a two-pyroxene, olivine, low-silica andesitewith SiO2 about 56% (Houghton & Hackett 1984). Wepropose the name Ohakune Tephra Formation (Oh), withthe type section in aroad cutting at S20/176974 (see Houghton& Hackett 1984, fig. 9), where the stratigraphic position of thetephra beneath Kawakawa Tephra is clear. The type area iswithin 1 km of this site. Reference sections are located in thequarries west of Ohakune (at S20/175976; S20/174979), asdescribed by Houghton & Hackett (1984). The tephra layerlies within loess overlying fluvial sediment and is closelyoverlain by Kawakawa Tephra. A single radiocarbon age oncharred twigs collected from the coarse lapilli layer in themiddle of the formation (the middle Pa+Pb bed of Houghton& Hackett 1984) is 31 500 ± 300 yr B.P. (WK1260: P. C.Froggatt & D. J. Lowe unpubl. data 1988).
Loisels PumiceLoisels Pumice (Wellman 1962) is a distinctive, dense, grey-white banded rhyolitic pumice found in beach depositsthroughout the east coast of New Zealand and on ChathamIsland (B.G. McFadgen pers. comm. 1987). Its identity andrelationship to some other sea-rafted pumices was discussed
Froggatt & Lowe—L. Quat tephra formations, N.Z. 97
by Pullar et al. (1977). Loisels Pumice has proved particularlyvaluable for coastline and archaeological studies (e.g.,McFadgen 1985). The pumice is highly vesicular with ahoneycomb texture resembling a foam, and has a mineralogyof hypersthene-augite-labradorite. The appearance of thepumice and its glass chemistry (P. C. Froggatt unpubl. data)are unlike anything known from New Zealand volcanoes, andstrongly resemble pumice erupted from some Pacific islands(e.g., Metis Shoal: Melson et al. 1970) or the pumice washedashore from the South Sandwich Island eruption in 1962(Coombs & Landis 1966). The exact sourceof Loisels Pumiceis unknown, but is probably in the Pacific, judging from oceancurrent patterns. Radiocarbon ages on material associatedwith Loisels Pumice are listed in Appendix 1. The ages formtwo clusters with pooled mean ages of 610 ± 20 yr B.P. and1250 ± 40 yr B.P. The older cluster of ages are on shellassociated with a drift pumice of Loisels-like appearance andchemistry (P. C. Froggatt unpubl. data) from Tokerau Beach,Northland (N. Osborne pers. comm. 1989) suggesting theremay be an older drift event. Sea-rafted pumices can be movedagain by the sea after their initial deposition on the shore.They should be regarded as less reliable time markers thanairfall tephra layers (Pullar et al. 1977).
Status of other named tephra deposits(1) Ohui Ash, Papanetu TephraOhui Ash (Wellman 1962) found ait Ohui Beach on theCoromandel Peninsula is sea-rafted Taupo pumice (Pullar etal. 1977). Papanetu Tephra is distal Karapiti Tephra (Froggatt& Solloway 1986). Both names have lapsed.
(2) Leigh PumiceLeigh Pumice is a sea-rafted pumice deposit named byWellman (1962). Because the original type section is indoubt, Pullar etal. (1977) were unable to examine itin relationto other sea-rafted pumices. It thus has uncertain status and novalue as a stratigraphic marker, and the name should lapse.
(3) Stent AshThe Stent Ash (Wellman 1962) is a 1 cm thick, pink fine ashfound within estuarine and peaty muds at the mouth of theOnaero River (Neall & Alloway 1986) and other coastalsections in north Taranaki. A sample collected from thecentral 5 mm of the lay er, and sieved to exclude grains coarserthan 0.25 mm, has a hypersthene-dominant mineralogy and aglass chemistry typical of a Holocene, Taupo-source tephra(P.C.Froggatt unpubl. data). Itis probably Waimihia Tephra,based on stratigraphic grounds and 14C ages on peat frombeneath the tephra at several localities in Taranaki (Allowayet al. 1988; B. V. Alloway and D. J. Lowe unpubl. data).
(4) Named soil-forming "Ash" depositsA number of terms, including "Tirau Ash", "Mairoa Ash",Waihi Ash", "Gisborne Ash", and "Whangamata Ash", wereintroduced during reconnaissance soil mapping in centralNorth Island (Grange 1931; New Zealand Soil Bureau 1954).These terms were used to describe; the composite parentmaterials of tephra-derived soils in different regions andare essentially geographical "hold-all" names, not geologicalformations. Subsequent studies on the parent materials ofthese soils have identified many of the constituent tephraformations (Pullar & Birrell 1973c; Hogg & McCraw 1983;Lowe 1988a). We thus recommend that the early terms bediscontinued to avoid confusion, and suggest that soils withcomposite tephra parent materials are described instead, for
example, as "post-Kawakawa Tephra deposits" or "post20 000 year old tephra deposits including ... Tephra", asappropriate.
FERROMAGNESIAN MINERAL ASSEMBLAGES
Determination of the dominant ferromagnesian mineralassemblage is the best initial laboratory guide to tephraidentification. The relative abundance of each mineral species,determined by point counting, is useful for identification, butexperience has shown that the presence (but not absence) ofkey minerals is of most value. We stress, however, thatpositive correlations of tephra can commonly only be madeusing multiple criteria (e.g., Froggatt 1983; Lowe 1988a, b).
The observed mineral assemblages fall into six maingroups, first recognised in part by Ewart (1963,1968,1971)and developed by Kohn (1973). These assemblages are listedbelow, with mineral species in usual order of abundance,followed by minerals that may or may not be present in smallamounts (±). The diagnostic or dominant mineral in eachassemblage is underlined:
(1) hvpersthene ± augite ± hornblende(2) hypersthene + hornblende + augite(3) hypersthene + hornblende + biotite(4) hypersthene + cummingtonite + hornblende(5) hypersthene + augite + hornblende(61 aegirine ± riebeckite ± aenigmatite ± olivine ± tuhualite
Assemblage 4 (cummingtonite-bearing) is restricted toeruptives from the Haroharo complex within OkatainaVolcanic Centre (Ewart 1968), and assemblage 6 is restrictedto pyroclastics from Tuhua Volcanic Centre, Mayor Island(Marshall 1932, 1936; Buck et al. 1981; Hogg & McCraw1983; Lowe 1988a). Tephra layers classified into each groupare listed in Table 4. Some tephra formations show a changein mineral assemblage stratigraphically through the depositand these have multiple listings.
CHRONOLOGY OF THE LATE QUATERNARYTEPHRA FORMATIONS
Age and dateWe have used the term "age" rather than "date" for thechronology produced by the isotopic radiocarbon datingmethod, as recommended by Colman et al. (1987). A "date"is a specific point in time, whereas an "age" is an interval oftime measured back from the present. Colman et al. (1987)and the North American Commission (1985) recommendedthe use of ka and Ma (thousand and million years ago,respectively) for ages, and the use of yr B.P. for conventionalradiocarbon ages measured from A.D. 1950.
Half-lives, secular and reservoir correctionsAll ages listed and discussed here are "conventional ages"based on the old (Libby) half life of 5568 ± 30 years, ratherthan the "new" half life of 5730 ± 40 years. We have notconverted any ages to new half life, and have determinedcalendar ages for only two tephra formations. The recentdetailed curves and tables of Stuiver & Pearson (1986) orStuiver & Becker (1986) can be used for this purpose. Theages obtained on shell samples (marine carbonates) have notbeen corrected for the reservoir effect.
98 New Zealand Journal of Geology and Geophysics, 1990, Vol. 33
Numerous ages have become available for nearly all thetephra layers erupted within the range of radiocarbon dating(until recently about 40 000 years). Some of these ages havelater proved unreliable for dating a specific tephra. In somecases the tephra identity or exact sample location is in doubt;in others, multiple ages or stratigraphic successions of agessuggest that any single age could be anomalous. Theavailability of paired ages from above and below a tephra,especially in peat or organic lake sediment, has considerablystrengthened the available chronology (e.g., Howorth et al.1980; Lowe et al. 1980; Lowe 1988a).
Published ages are scattered through many papers, somenot dealing primarily with tephrostratigraphy, and it is oftendifficult to locate all ages for a tephra layer and to assess theirvalue. We have listed in Appendix 1 (updated copies areavailable from either author) details of all the ages availableto us (total 384) for each tephra, together with an assessmentof the value of each age for dating that tephra. We have thenselected the most reliable ages and calculated the pooledmean, weighted by the standard deviation, on each agedetermination (Ward & Wilson 1978; Gupta & Polach 1985),assuming the ages are normally distributed. The weightedmean (Ap) and the standard error of the mean of the ages(seAp) are calculated from the individual ages (A. ) andassociated errors (sej) thus:
Ap = I ( A . / s e 2 ) / H / s e i2
Ap i
Table 1 lists these mean ages and pooled errors and thenumber of reliable ages used to calculate the mean. Severaltephra formations still require further ages, and some of theolder tephras from both Okataina and Taupo remain undated(Table 1 and Appendix 1).
AGES OF SOME TEPHRA FORMATIONS
Kaharoa Tephra FormationThe 15 available ages on Kaharoa Tephra (Appendix l)rangefrom 610 ±60 yr B.P. (NZ1765) to 980 ±60 yr B.P.
(NZ7472). The ages are on wood, charcoal, and peat withinandbracketing the tephrabut there areno consistent differencesin age between sample type, nor is there any evidence for aprolonged hiatus in the eruption of Kaharoa Tephra (I. A.Nairn pers. comm. 1984). Consequently, we have treated allages as valid and representing the same event. They give apooled mean age of 770 ± 20 years. This age converts to acalibrated (calendar years) date of A.D. 1270 with a l a rangeof A.D. 1264-1275 (Stuiver & Pearson 1986).
Taupo Tephra FormationHealy (1964b) was the first to calculate a weighted mean agefor Taupo Tephra of 1819 ± 17 yr B.P., updated to 1820 ± 80yr BP. by Froggatt (1981d). Wilson et al. (1980) claimedliterary evidence for this eruption in Roman and Chineserecords. Objections were raised by Froggatt (198 le), andStothers & Rampino (1983) demonstrated errors in thetranslation of the Roman text used by Wilson et al. (1980) andsuggested that the literary reference was to a supernova.There is no evidence that the Chinese reference was to aneruption and, furthermore, it is not dated with sufficientaccuracy to constrain the age of Taupo Tephra.
Calendar ageThe mean radiocarbon age for Taupo Tephra (Table 1) is 1850± 10 yr B.P., based on 41 ages. Conversion of this age to acalendar age is problematic, falling in a period of rapid 14Cfluctuation (multiple curve intercepts) and low curveprobability (large error). The curves of Stuiver & Pearson(1986), based on a 20 year tree-ring series, convert this age toA.D. 214 with a l a range of A.D. 138-230 after the 30 yearhemisphere correction has been subtracted (Stuiver & Pearson1986). Curve matching of a sequence of 14C ages on tree ringsfrom trees killed by the Taupo eruption (J. G. Palmer pers.comm. 1988) gives a date of A.D. 177 ( l a range of A.D.166-195).
Palmer et al. (1988) deduced that the eruption occurred inmid-late summer, because trees destroyed by the eruption donot show an outer latewood ring. This is substantiated by
Table 4 The dominant feiromagnesian mineral assemblages for the late Quaternary silicic tephra deposits, listed by mineralassemblage (see text), volcanic centre, and relative age.
ASSEMBLAGE 1
Hyp + aug ± hbl
Taupo VC
Taupo(all members)
MaparaWhakaipoWaimihia
(both members)HinemaiaiaMotutereOpepePoronuiKarapiti
ASSEMBLAGE 2
Hyp + bbl ± aug
Okataina VCMamakuWaiohauRotorua
(lower part)Te RereOmatoroaAwakeriMangaoneTahunaNgamotu
Taupo VCKawakawa
(both members)PoihipiOkaiaTihoiWaihoraOtake
ASSEMBLAGE 3
Hyp + hbl + bio
Okataina VCKaharoaRotorua
(top part)RerewhakaaituOkarekaEarthquake FlatRotoiti
(top part)
Maroa VCPuke tar ata
ASSEMBLAGE 4
Hyp + cgt ± hbl
Okataina VCWhakataneRotomaRotoiti
(all membersexcept Matahi)
ASSEMBLAGES
Hyp + aug ± hbl
Okataina VCHauparuTeMahoeMaketu
ASSEMBLAGE 6
Aegirlne
Tuhua VC
Tuhua
Froggatt & Lowe—L. QuaL tephra formations, N.Z. 99
Clarkson et al. (1988) who examined the forest preserved atPureora and found fruits and seeds only from early fruitingspecies.
Kawakawa Tephra FormationKawakawa Tephra is the most widespread late Quaternarytephra studied and provides an important timeplane near thenadir of the Last Stadial of the Last Glacial (Vucetich & Pullar1969). All radiocarbon ages summarised by Vucetich &Howorth (1976a), two ages from Buller Gorge (Campbell1986; Wilson et al. 1988), and four accelerator mass-spectrometry ages on pretreated samples from Westland(Hammond etal. 1988a, b) are on organic sediment associatedwith the tephra layer. These 12 ages have a pooled mean of20 220 ± 115 years. Early attempts to date directly theeruption using charred material in Oruanui Ignimbrite haveproduced four sets of near-infinite ages: >45 000 years,resampled to give 32 320 ± 1750 yr BP . (NZ3128 andNZ3211; S. Self pers. comm. 1980); >42100 yr BP., and>45 600 yr BP. (NZ4575 andNZ4576; Froggatt 1982a). Ondetailed examination the material sampled in both cases wasfound to be charred lignite rather than extant vegetation andthus does not date any eruptive event. A fission-track age onglass sampled from North Canterbury is 20 300 ± 7100 yearsold (Kohn 1979).
Recently, Wilson et al. (1988) dated four samples of finecharcoal fragments from within the deposit itself (OruanuiIgnimbrite), giving a pooled mean of 22 590 ± 230 yr BP .This age is significantly older (c. 1290 years) than the optimalpair of ages (21 300 ± 450 yr BP.) from Buller Gorge(Campbell 1986). Charcoal is considered to give morereliableages than peat as the charcoal is formed by the eruptive eventitself and is generally less susceptible to contamination. Thediscrepancy in ages may be due to different samplepretreatment procedures, but the peat and sediment may bemildly contaminated by younger carbon. The effects of variouspretreatments on contaminants in samples of organic silt andpeat associated with Kawakawa Tephra in Westland arecurrently being assessed (Hammond et al. 1988a, b).
Mangaone, Awakeri, and Omataroa TephraFormationsThe pooled mean age of 27 730 ± 350 yr BP. for MangaoneTephra is not significantly different from that of 28 220 ± 630yr BP. for Omataroa Tephra (Table 1). However, AwakeriTephra andMangaoneTephrabothunderlieOmataroaTephrastratigraphically (Howorth 1975), and hence are older. If allthe ages on Omataroa Tephra are accepted as valid, then someof the younger ages obtained on Mangaone Tephra (i.e. thoseless than c. 27 000 years ago) are likely to be underestimates.On this basis, Mangaone Tephra may have been eruptedc. 30 000 years ago.
Rotoiti Tephra FormationSeveral radiocarbon ages on this formation are close to, orbeyond, the current limits of the dating technique (McGloneet al. 1984). As several infinite ages have been returned(Appendix 1) and must be regarded as valid ages, the finiteages of c. 42 000-44 000 years are likely to be minima. Thepreservation of Rotoehu Ash at Mahia Peninsula on a marine-cut surface thought to be 54000 ± 4000 years old (K.R.Berryman pers. comm. 1985), and between the second andthirdloess units on MamakuPlateau (Kennedy 1987), suggests
an age of c. 50 000- 55 000 years for this formation, bycomparison with the oxygen isotope stage chronology.
A U-Th disequilibrium age on whole sample andtitanomagnetite separates is c. 71000 ± 6000 years (Ota et al.1989b). However, this age should be regarded as provisionalbecause the isochron from which the age is derived (Ota et al.1989, fig. 4) is essentially based on only one data point, thatof the whole rock sample. The other three points are on theequilibrium line or within two standard deviations of it (C. H.Hendy pers. comm 1989). In addition, analyses of at least twomineral species, and of ^ U as well as ^'U, are desirable indating pyroclastic deposits such as Rotoehu Ash (Hendy et al.1980). Other dating methods, such as accelerator mass-spectrometry, low-level scintillation spectrometry, andthermoluminescence dating have not yet produced definitiveages for this formation.
DISTRIBUTION OF LATE QUATERNARYTEPHRA
Isopach maps showing the thickness distribution of most lateQuaternary tephras are available. Many of the earlier mapswere recompiled and updated by Pullar & Birrell (1973a, b).Maps based on new data for some of the Taupo and Rotoruasubgroup tephras and Tuhua Tephra have been published(Walker 1980,1981 a,b; Froggatt 198 lb; Froggatt & Solloway1986; Hogg & McCraw 1983; Lowe 1988a). Table 1 lists thereferences to published isopach maps for each tephra. Thedistribution of some of the late Pleistocene tephras fromTaupo is poorly known because of inadequate exposure.
Nearly all the isopach maps show a dominant easterlydistribution pattern with only a few tephra deposits (Ka, Mk,Re) having a more northerly aspect Despite the large volumeand widespread distribution of Rotoehu Ash, it has not yetbeen located south of Taihape and is rarely seen south ofTaupo. Its occurrence in Northland is documented in Lowe(1987).
Kawakawa Tephra is the most widely distributed lateQuaternary tephra in New Zealand, being found throughoutmost of the country and in many offshore cores. It is wellpreserved on the West Coast (Mew et al.1986), Marlborough(Campbell 1979, 1986), Canterbury (Kohn 1979), andChatham Island where it was locally named Rekohu Ash(Hay etal. 1970; Mildenhall 1976). Glass shards attributed toKawakawa Tephra have been isolated from loess near Timaru(Eden & Froggatt 1988) and Southland (Mclntosh et al.1988).
ERUPTED VOLUMES OF LATE QUATERNARYTEPHRA
Methods of calculating erupted volumes vary considerably,but all are approximations based on extrapolations of assumedrelationships of thickness or volume distribution. All methodsrequire a reliable isopach map from which variations ofthickness and volume with distance or area can be calculated.Approximate volumes of many of the late Quaternary tephradeposits (Pullar & Birrell 1973a; Vucetich & Pullar 1973;Howorth 1975; Vucetich & Howorth 1976b) were firstcalculated from the circular isopach formula of Cole &Stephenson (1972) and are certainly underestimates. A reviewof methods andaconsistentsetof calculations were presentedby Froggatt (1982b). Other recent calculations, based on a
100 New Zealand Journal of Geology and Geophysics, 1990, Vol. 33
Table S The volume of airfall tephra, ignimbrite, and lava(extrusives) produced during each eruptive episode. Asterisks indicatevolumes are estimates only and are not based on calculations fromisopachmaps or other reliable thickness data. Blank values show thatextrusive bodies or ignimbrite have not yet been positively identifiedfor that eruptive episode, or an estimate is currently difficult todetermine. Erupted volumes have been converted to magma volumesusing densities for silicic airfall tephra, unwelded ignimbrite, basaltictephra, silicic lava, and silicic magma of 1.0,1.25,2.0,2.3, and 2.3Mg/m3, respectively.
Volume (km3)
Formation & members Airfall Ignimbrite Lava Magma
Okataina Volcanic CentreTarawera Tephra
Rotomahana MudTarawera Scoria
Kaharoa 5 2.5Rotokawau 0.7 0.5Whakatane 10 9Mamaku 6 15Rotoma 12 2Waiohau 18 4Rotorua 7 1Rerewhakaaitu 7 2Okareka 8 5Te Rere 6* 8OmataroaAwakeriMangaoneHauparuTeMahoeMaketuTahunaNgamotuEarthquake Flat Tephra
Rifle Range AshEarthquake Flat Ig.
Rotoiti TephraRotoehu AshRotoiti IgnimbriteMatahi Scoria
Total for OkatainaTaupo Volcanic CentreTaupo Tephra
Taupo IgnimbriteTaupo LapilliRotongaio AshHatepe AshHatepe Lapilli
MaparaWhakaipoWaimihia Tephra
Waimihia IgnimbriteWaimihia Lapilli
HinemaiaiaMotutereOpepePoronuiKarapitiKawakawa Tephra
Oruanui IgnimbriteAokautere Ash
PoihipiOkaiaTihoiWaihoraOtakeTotal for Taupo:
Maroa Volcanic CentrePuketarataTuhua Volcanic CentreTuhua 1*Total for Taupo Volcanic Zone(in the last c. 50 000 years): 374.5
250.7
106
12187786*
162
16100.3
152*2
2*
9190
1*238
17.5
1212.5222
14
1431432
70
7017512
134.5
1*
5*150
150
166
7070
55
150150
225
49
0.2
0.10.1
0.50.5
1.4
0.1
1.54.0
13.517.57.0
124.05.08.5
11.5101.0
104.50.16.511
12.7
120.540800.5
242.8
45.53850.51.01119.036.01.50.62.02.01.5
11282300.533.00.51
184.1
391 505 428.9
variety of methods, are given in Froggatt (1981a, c), Froggatt& Solloway (1986), Houghton & Wilson (1986), Nairn(1981, 1986), Walker (1979, 1980, 1981a), Walker et al.(1984), and Wilson et al. (1986).
The current best estimates of volume of airfall tephra,ignimbrite, and lava for each formation, from the referenceslisted above, are given in Table 5 and have also been convertedto equivalent magma volumes. The list indicates that the twolargest late Quaternary eruptions, volumetrically, were theKawakawa and Rotoiti eruptive episodes. The total volume ofrhyolitic material erupted from TVZ within the last c. 50 000years is estimated at about 370 km3 of airfall tephra, 390 km3
of ignimbrite, and 50 km3 of extrusive lava, together equivalentto about 430 km3 of magma.
ACKNOWLEDGMENTS
The field knowledge and enthusiasm of Colin Vucetich and the lateAlan Pullar has introduced many people to the complexities andvalue of tephrostratigraphy, and we are grateful for their guidanceand for many discussions about tephra nomenclature. I. A. Nairn,R. M. Briggs, J. D. McCraw, and G. P. L. Walker provided usefulcomments or information for aspects of this work, and J. G. Palmerprovided unpublished 14C ages on his tree-ring chronology on TaupoTephra. The assistance of Martin Manning and the New Zealand ~Radiocarbon Dating Laboratory, DSIR, and Alan Hogg of theUniversity of Waikato Radiocarbon Dating Laboratory, have beeninvaluable in compiling the ages. We are especially grateful to thepeople listed in the footnote to Appendix 1 for permission to quotetheir unpublished ages.
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Ota, Y.; Omura, A.; Iwata, H. 1989: ^"Th-^nj age of Rotoehu Ashand its implications for marine terrace chronology of easternBay of Plenty, New Zealand. New Zealand journal ofgeology and geophysics 32:327-331.
Palmer, J. G.; Ogden, J.; Patel, R. N. 1988: A 426-year floating tree-ring chronology from Phyoclladus trichomanoid.es buriedby the Taupo eruption at Pureora, central North Island, NewZealand. Journal of Royal Society of New Zealand 18:407-415.
Pullar, W. A. 1970: Pumice ash beds and peaty deposits ofarchaeological significance near Lake Poukawa, Hawke'sBay. New Zealand journal of science 13: 687-705.
-1973: Tephra marker beds in the soil and their applicationin related sciences. Geoderma 10:161-168.
Pullar, W. A.; Birrell, K. S. 1973a: Age and distribution of lateQuaternary pyroclastic and associated cover deposits of theRotorua and Taupo area. North Island, New Zealand. NewZealand Soil Survey report 1.
1973b: Age and distribution of late Quaternary pyroclasticand associated cover deposits of central North Island, NewZealand. New Zealand Soil Survey report 2.
1973c: Parent materials of Tirau silt loam. New Zealandjournal of geology and geophysics 16: 677-686.
Pullar, W. A.; Heine, J. C. 1971: Ages, inferred from 14C dates, ofsome tephra and other deposits from Rotorua, Taupo, Bay ofPlenty, Gisborne, and Hawke's Bay districts. Pp. 118-138in: Radiocarbon Users' Conference, 17-18 August 1971,Lower Hutt, New Zealand.
104 New Zealand Journal of Geology and Geophysics, 1990, Vol. 33
Pullar, W. A.; Nairn, I. A. 1972: Matahi Basaltic Tephra Member,Rotoiti Breccia Formation. New Zealand journal of geologyand geophysics 15:446-450.
Pullar, W. A.; BirrelL K. S.; Heine, J. C. 1973: Named tephras andtephra formations occurring in the central North Island, withnotes on derived soils and buried paleosols. New Zealandjournal of geology and geophysics 16:497-518.
Pullar, W. A.; Kohn, B. P.; Cox, J. E. 1977: Airfall Kaharoa Ash andTaupo Pumice, and sea-rafted Loisels Pumice, Taupo Pumice,and Leigh Pumice in northern and eastern parts of the NorthIsland, New Zealand. New Zealand journal of geology andgeophysics 20: 697-717.
Rogan, A. M. 1982: A geophysical study of the Taupo VolcanicZone, New Zealand. Journal of geophysical research 87:4073^1088.
Schmid, R. 1981: Descriptive nomenclature and classification ofpyroclas tic deposits and fragments: recommendations of theIUGS Subcommission on the systematics of igneous rocks.Geology 9: 41-43.
Self, S. 1983: Large-scale phreatomagmatic silicic volcanism: acase study from New Zealand. Journal ofvolcanology andgeothermal research 17: 433-469.
Self, S.; Healy, J. 1987: Wairakei Formation, New Zealand:stratigraphy and comlation.New Zealand journal of geologyand geophysics 30: 73-86.
Self, S.; Sparks, R. S. J. 1978: Characteristics of widespreadpyroclastic deposits formed by the interaction of silicicmagma and water. Bulletin volcanologique 46:196-212.
-1979: The postglacial history of the MyVatin area. Oikos
-ed. 1981: Tephra studies. Dordrecht, D. Riedel.
Seward, D. 1976: Tephrostratigraphy of the marine sediments in theWanganui Basin, New Zealand. New Zealand journal ofgeology and geophysics 19: 9-20.
Sparks, R. S. J.; Walker, G. P. L. 1977: The significance of vitric-enriched airfall ashes associated with crystal-enrichediffumbnxe,s. Journalofvolcanology and geothermalresearch2: 329-341.
Sparks, R. S. J.; Self, S.; Walker, G. P. L. 1973: Products ofignimbrite eruptions. Geology 1:115-118.
Stothers, R. B.; Rampino, M. R. 1983: Volcanic eruptions in theMediterranean before A.D. 630 from written andarchaeological sources. Journal of geophysical research 88:6357-6371.
Stuiver, M; Becker, B. 1986: High-precision decadal calibration ofthe radiocarbon time scale, A.D. 1950-2500 B.C.Radiocarbon 28: 863-910.
Stuiver, M.; Pearson, G. W. 1986: High precision calibration of theradiocarbon time scale, A.D. 1950-500 B.C. Radiocarbon28: 805-838.
Taylor, N. H. 1953: The ecological significance of the central NorthIsland ash showers—The soil pattern. Report of 2nd annualmeeting New Zealand Ecological Society: 11-12.
Thomas, A. P. W. 1888: Report on the eruption of Tarawera andRotomahana, New Zealand. Wellington, Government Printer.
Thompson,B.N. 1964: Quaternary volcanism of the Central VolcanicRegion. New Zealand journal of geology and geophysics 7:45-66.
Thorarinsson, S. 1944: Tefrokronologiska studier pa Island.Geografiska annaler 26: 1-217.
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32:17-28.1981: Tephra studies and tephrochronology: a historical
review with special reference to Iceland. Pp. 1-12 in: Self,S.; Sparks, R. S. J. ed. Tephra studies. Dordrecht, D. Reidel.
Topping, W. W. 1973: Tephrostratigraphy and chronology of lateQuaternary eruptives from the Tongariro Volcanic Centre,New Zealand. New Zealand journal of geology andgeophysics 16: 397-424.
Topping, W. W.; Kohn, B. P. 1973: Rhyolitic tephramarker beds inthe Tongariro area,North Island, Nev/Zssland.NewZealandjournal of geology and geophysics 16: 375-395.
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Froggatt & Lowe—L. QuaL tephra formations, N.Z. 105
APPENDIX 1
Radiocarbon ages relevent to New Zealand tephra layers
All the radiocarbon ages (in conventional years B .P.) known to us for each tephra formation are listed here. They are givenin alphabetical order by tephra formation, then by laboratory and age number. NZ and NZ A=gas counter and acceleratormass spectrometry, respectively, at New Zealand Radiocarbon Dating Laboratory, DSIR, Lower Hutt; WK=Universityof Waikato Radiocarbon Dating Laboratory, Hamilton; Q = Godwin Laboratory, University of Cambridge, Cambridge;GAK = Gakushuin University Radiocarbon Dating Laboratory, Tokyo. All ages are quoted as conventional ages basedon the old half life (5568 ± 30 years). The material dated is listed as C = charcoal, CW = charred wood, E = extract fromchemical treatment, H = humus, G = gyttya (lake sediment), M = organic mud, P = peat, Po = pollen, Pf = fine peat, Pr= roots in peat, R = residue from chemical treatment, S = soil, SE = seeds, SH = shell, W = wood. The reference wherefirst quoted in full or discussed in relation to the tephra is numbered; the key is below. Our assessment of the value of theage is based on the type of material dated, proximity to the tephra, whether one of a paired set, and whether any doubtabout the sample or tephra identity exists. The ratings are 1 = optimal; 2=useful; 3=little current value. Ages with ratingsof 1 or 2 have been used to calculate error-weighted means which are listed in Table 1. For ages currently unpublished,the sources (pers. comm. 1988 and 1989) are lettered and listed below. In the Comments column, min = sample overliestephra; max = sample underlies tephra.
1 Buck et al. (1981)2 Campbell (1986)3 Cole (1970a)4 Froggatt (1981c)5 Froggatt (1981b)6 Froggatt & Solloway (1986)7 Goh & Pullar (1977)8 Grant-Taylor & Rafter (1963)9 Grant-Taylor & Rafter (1971)10 Green (1987)12 Green & Lowe (1985)13 Hay et al. (1970)14 Healy (1964b)15 Hogg &McCraw (1983)16 Hogg etal. (1987)17 Howorth & Vucetich (1976)18 Howorth & Ross (1981)19 Howorth et al. (1980)20 Hull (1986)21 Kennedy et al. (1978)
Sources of unpublished dates:a P. C. Froggattb B. V. Alloway & D. J. Lowec P. L. Singletond D. J. Lowe & R. M. Newnham
Tephra C14 Age Stdformation Lab Number (yr B.P.) deviation
Hauparu NZ 3404 39,000Hauparu NZ 3405 35,700Hinemaiaia NZ 3160 4,220Hinemaiaia NZ 3161 4,800Hinemaiaia NZ 4574 4,650Hinemaiaia WK 496 4,490Hinemaiaia WK 497 4,530Hinemaiaia WK 541 4,490Hinemaiaia WK 542 4,470Hinemaiaia WK 662 4,260Hinemaiaia WK 663 3,510Hinemaiaia WK 1336 4,580Hinemaiaia WK 1337 4,640Hinemaiaia WK 1437 4,550Hinemaiaia WK 1438 4,490Kaharoa GAK 10446 920Kaharoa NZ 10 930Kaharoa NZ 872 850Kaharoa NZ 1765 610Kaharoa NZ 4304 950Kaharoa NZ 4803 680Kaharoa NZ 4804 650Kaharoa NZ 4991 670Kaharoa NZ 4992 1,145Kaharoa NZ 4993 780Kaharoa NZ 5087 940Kaharoa NZ 5993 630Kaharoa NZ 7472 980Kaharoa WK 1013 710Kaharoa WK 1014 680Kaharoa WK 1346 660
56001300
60508060607070
14015012011010090
100706060608560606558906060
11013045
2223252627282930313233343536373839404243
efghi
Sampletype
MMPPCPPGGGGPPPPSWPCCPPCWCCcppp
CW
Kohnetal. (1981)Lowe (1986)Lowe (1988a)Lowe & Green (1987)Lowe & Hogg (1986)Lowe et al. (1980)McGlone (1983a)McGlone (1981)McGlone (1983b)McGlone etal. (1984)Mildenhall (1976)Nairn (1986)Nairn (1980)Nairn (1981)Pullar (1970)Pullar etal. (1973)Pullar & Heine (1971)Topping & Kohn (1973)Vucetich & Howorth (1976a)Vucetich & Pullar (1964)
N. M. KennedyD. J. Lowe & A. GB. ClarksonB. V. AllowayN. Osborne
Assessed
i. H o g g
value References Collector
2 322 3121 231 231 4,231 23,217,161 23,217,161 23,16,251 23,16,251 23,16,251 16,253 641 641 I1 I2 S91 8,432 55,362 55,361 361 30,361 30,31,361 29,36,343 361 361 36,341 361 591 d1 d1 f
HoworthHoworth
NeallNeall
FroggattRogers, Lowe, HoggRogers, Lowe, HoggLowe, Green, HendyLowe, Green, HendyLowe, Hendy, OuelletLowe, Hendy, Ouellet
444546474849505152535455565758596061626364
jk1z
de Lange, Crowcroft, Gilmourde Lange, Crowcroft, Gilmour
Wigley, Edwards, etal.Wigley, Edwards, et al.
Ota, Beanland, BerrymarBaumgart, Vucetich
CoxCox
NairnLawlor & McGloneLawlor & McGlone
NairnNairnNairn
Nairn & BishopNairn
Ota, Beanland, BerrymarLowe, Newnham, LoweLowe, Newnham, Lowe
Lowe
l
Vucetich & Pullar (1969)Vucetich & Pullar (1973)Mew et al. (1986)Froggatt & Rogers (1990)Wilson etal. (1988)Green (1963)Wellman(1962)Leahy (1974)McFadgen (1982,1985)Houghtonetal. (1985)Berryman & Hull (1984)Pullar et al. (1977)Pullar (1973)Harris (1963)Houghton & Wilson (1986)Ota etal. (1988)Atkinson (1973)Hammond et al. (1988a,b)Dahm (1987)Abrahamson (1987)de Lange (1989)
J. Dahm & A. G. HoggI. A. NairnG. N. A. Wigley & D. J. LoweRadiocarbon files, Institute of
Nuclear Sciences, DSIR
Comments
min(=R5031/1)max (=R5031/2)
minmax (min for Wk)
max (also min for Wk)max (also min for Wk)
minmax
max (also min for Wk)min (?contaminated)
minmaxminmax
soil overlying Kamax
peat at Whangareicharcoal in humus
minmax
max (from large tree)
maxminmax
sample in block and ash flow
{Continued on next page)
106
[Continued from previous page)
New Zealand Journal of Geology and Geophysics, 1990, Vol. 33
Tephraformation
KarapitiKarapitiKarapitiKarapitiKawakawaKawakawaKawakawaKawakawaKawakawaKawakawaKawakawaKawakawaKawakawaKawakawaKawakawaKawakawaKawakawaKawakawaKawakawaKawakawaKawakawaKawakawaKawakawaKawakawaKawakawaKawakawaKawakawaKawakawaKawakawaKawakawaKawakawaKawakawaKawakawaKawakawaKawakawaKawakawaKawakawaKawakawaKawakawaKawakawaKawakawaKawakawaLoiselsLoiselsLoiselsLoiselsLoiselsLoiselsLoiselsLoiselsLoiselsLoiselsLoiselsLoiselsLoiselsLoiselsLoiselsLoiselsMamakuMamakuMamakuMamakuMamakuMamakuMamakuMamakuMamakuMamakuMamakuMamakuMamakuMamakuMamakuMamakuMamakuMamakuMamakuMamakuMamakuMamakuMamakuMamakuMamakuMamakuMamakuMamakuMamakuMamaku
Lab
NZNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZANZANZANZANZANZANZANZANZANZANZANZANZANZANZANZANZANZANZA
QQQQNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZWKNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZWKWKWKWKWKWKWKWKWKWK
C14Number
1372137313744847
12330373520521522
105631033128321145754576655771447373239
0240256258262263264269270271287293328329335371372373
2665266626672668354396631632651
1296129747264727729175607568761376487649874719
1152139914001401140214521453431043114542493950336741702970307039704370587557227228524525547562570571604612
Age(yrB.P.)
9,7809,7009,7909,910
20,67020,00039,60020,50021,90035,00019,85020,100
>45,00032,32042,100
>45,60015,60021,30021,30015,20413,14614,4588,7107,772
12,56317,8985,975
13,86917,51712,52312,07918,80711,87019,63515,24015,54020,67019,17022,63022,47022,63022,720
640799520700930450520973
1,2331,0301,360
7261,4412,3831,449
7808,0507,0507,7607,7306,4307,4108,0307,4407,3907,6206,3407,4407,3406,8804,7406,3604,6404,4406,9807,6606,8308,1707,9205,8007,9805,8507,2007,1405,4108,560
Stddeviation
170210160130300500
2000430510
1700310400
017505190
0250450460239
1428364300267366336248246462170344377122331510240470480
450/430410/380470/440580/540
504040605040404028604574345452
16510577
13513513513515015011011010070
1406075907070908090908070
15070
12011015080
Sampletype
WPWCWPPPPPWWPPCCPPPEEEEEPREERRERPRPoRRRCCCCCCCSHWSHSHSHSHSHSHSHSHSHSHCCCERERCCCCPCCPPPPPPcGGGGGPGGGP
Assessedvalue
1111123113113333322333333333333232332211112232322333333332212222111131113233111323331133
References
40,640,640,65,6
39,8,44,428,44,42
8,139,44,42,609,44,42,60
9,44,4239,36,42
33zzaa462
486161616161616161616161616161616161616148484848
49,5250,5250,5250,5250,5251,5251,52
iiiiiiii
6339,9
39,45,77777773636a3636Cccccck
12,16,2516,2516,2516,2516,25
1616,2516,25
1616
Collector
ToppingToppingToppingFroggatt
Berry
MutchPohlen, HarrisGrant-Taylor
Nairn
SelfSelf
FroggattFroggatt
MoarCampbellCampbellHammondHammondHammondHammondHammondHammondHammondHammondHammondHammondHammondHammondHammondHammondHammondHammondHammondHammondHammond
WilsonWilsonWilsonWilsonGolson
WellmanWellmanWellmanWellman
LeahyLeahy
Enright, OsborneEnright, OsborneEnright, OsborneEnright, OsborneEnright, OsborneEnright, OsborneEnright, OsborneEnright, Osborne
AbranamsonPullar
Pullar, BirrellGohGohGohGohGohGohNairnNairn
FroggattNairnNairn
SingletonSingletonSingletonSingletonSingletonSingleton
NairnLowe, GreenLowe, GreenLowe, GreenLowe, Green
Lowe, Green, HendyLowe, Hogg, Lane
Lowe, Green, HendyLowe, Green, Hendy
Comments
minminmax
in Hinuera Fm alluviumpeat 0.3 m beneath Rekohu Ash
maxmin
peat 1.5 m beneath tephra
Rekohu Ashlignite?
repeat of NZ3128lignite?lignite?
contaminatedmaxmin
lipids from NZA262humic acids from NZA262 (=4b in ref 61)
lipids from NZA262hydrolysate from NZA262fulvic acid from NZA262
untreated peatresidue from NZA262HCI:HF pretreatment
humic acid from NZA262residue from NZA262residue from NZA262
hydrolysate from NZA262HNO3 hydrolysis of NZA262
untreated (min)HNO3 hydrolysis of NZA328
pollen from NZA262HNO3 hydrolysisHNO3 hydrolysisHNO3 hydrolysis
charcoal in ig.charcoal in ig.charcoal in ig.charcoal in ig.
below Lsbelow Ls
above Ls, but long-lived treeabove Ls
well below Lsabove Lsabove Ls
shell above Lsshell below Ls
shell bank seaward of Lsshell below Lsshell with Ls
shell above Lsshell with mixed Ls and Taupo Pumice
shell with Lsin paleosol below Ls
max (paleosol on Rm)
extract of NZ1452residue of NZ1452extract of NZ1453residue of NZ1453
Poukawa: ?contaminated
underlies ashoverlies ash; root contam.underlies ash; ?contam.
overlies ash; root contam.overlies ash; root contam?
underlies ashdates dome collapse ?
mincontaminated
maxmin (max for Tu; thick sample)max (not adjacent to tephra)min (not adjacent to tephra)
maxmin
Lowe, Green, Boubee, Bergin min (thick sample)Lowe, McLeod mm (tentatively ident.) reworked sed
[Continued on next page)
Froggatt & Lowe—L. Quat. tephra formations, N.Z. 107
(Continued from previous page)
Tephraformation
MamakuMamakuMamakuMangaoneMangaoneMangaoneMangaoneMangaoneMangaoneMangaoneMangaoneMangaoneMangaoneMangaoneMangaoneMaparaMa paraMaparaMaparaMaparaMaparaMotutereMotutereMotutereOhakuneOiraOiraOmataroaOmataroaOmataroaOpepeOpepeOpepeOpepeOpepeOpepeOpepeOpepeOpepeOpepeOpepeOpepeOpepePoronuiPoronuiPoronuiPuketarataRangitotoRangitotoRerewhakaaituRerewhakaaituRerewhakaaituRerewhakaaituRerewhakaaituRotoitiRotoitiRotoitiRotoitiRotoitiRotoitiRotoitiRotoitiRotoitiRotokawauRotokawauRotokawauRotokawauRotokawauRotokawauRotomaRoto maRotomaRotomaRotomaRotomaRotomaRotomaRotomaRotomaRotomaRotomaRotomaRotomaRotomaRotomaRotomaRotomaRotoma
Lab
WKWKWKNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZWKWKNZNZNZWKNZWKNZNZNZNZWKWKWKWKWKWKWKWKWKWKWKWKWKWKWKNZNZNZNZNZNZWKWKNZNZNZNZNZNZNZNZWKNZWKWKWKWKWKNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZ
C14Number
62612691271866867868
113215561610161118121859194434063407
157178
10681069128915033950395148461260370105876
11361147185229230492520521707713
10001291129213201335351352491
5391220222716
15541607237238
0000
643877
11264303
5907356939940941942943719
119919431945308960206021602260236024602560266027602860296030603160326033
Age(yrB.P.)
8,0307,0607,030
21,90026,30030,10029,40026,10026,80025,00035,30031,40033,30027,00031,000
2,2702,1002,0102,1502,1302,2305,6805,3705,370
31,5008,3908,000
27,90029,70027,900
8,8507,6509,3708,7108,9308,6708,7008,9907,9109,0609,0508,3909,600
10,1609,9609,5609,180
750770
14,70012,46012,51014,70014,700
>43,90027,90023,20033,700
>41,00044,00041,700
>40,400>35,000
3,4402,2602,8202,3602,7002,3808,0507,3308,8308,8607,0408,7458,6718,6528,7658,7338,7728,7448,7958,6238,5046,7498,1458,6608,624
Stddeviation
330120100400700
1300800800
1400700
22001500200010002100
5510060506050
1309090
30013570
85015001200100016021080
10011013022070
11012028070
1309080
1705050
200160160220180
01500850
23000
53003500
00
7070606060
130105235
90120250
415252534153365342
13953
19953
127
Sampletype
GPPCCCSCERCCCPPCCPPPPPPccwcwcMMCGGPGGGGPPPPCPrPfPS
SHCCCCGG
MWRECWPWCGPPPPPPrCCCCCCCCCCCCCCECC
cE
Assessedvalue References Collector
3 166464
3 39.93 39,44
39,3239,32
322 322 32
322 32
4
;
•
•
•
36,343232
39,8,148,14
9,45,399,45,39
2 64I
4,19,234,19,23
4,23a,f
8,531
9,39,32,441 39,32
39,32
Lowe, Green, Boubee, Berginde Lange, Champion
de Lange, Crowcroft, GilmourPullar, King
PullarPullar
Pullar, Juene
NairnHoworthHoworth
HealyHealyPullarPullar
de Lange, RosenbergWigley
HoworthHoworthFroggattFroggattBrothers
BuckCox
Pullar, KohnPullar, Holmes
2 45,39,8,43,14 Vucetich3 16,251 12,113,25
27,1616,25
1 16,2516,25
2 16,253 47
6464
3 64a,f
1 27,161 27,16
27,163 a2 8
89,44,39,45
3 z3 Z
25,16,28
Lowe, GreenLowe, Green
Rogers, Lowe, HoggLowe, GreenLowe, Green
Lowe, Hendy, OuelletLowe.Hendy, Ouellet
Rogersde Lange, Rosenbergde Lange, Rosenbergde Lange, Champion
FroggattRogers, Lowe, HoggRogers, Lowe, HoggRogers, Lowe, Hogg
FroggattBrothersBrothers
Pullar
Lowe. Green16,25,28,12 Lowe, Green
39,173 173 173 172 9,39,32,441 9,39,321 39,322 362 161 83 103 103 103 103 102 9,39
39,38,4536
1 36,35,122 7t Z1 Z1 z1 z1 z1 z1 z1 Z1 Z1 Z1 Z1 z1 Z1 z
Pullar, KohnPullarPullarPullar
ThompsonCoxNairnNairn
Lowe, Green, Boubee, BerginKennedy
Green, Lowe, HoggGreen, Lowe, HoggGreen, Lowe, HoggGreen, Lowe, HoggGreen, Lowe, Hogg
Pullar
NairnNairn
Nairn
Comments
max (diluted; thick sample)straddles tephrastraddles tephra
contaminated with rootscontaminated with roots
extract of NZ1556residue of NZ1556
(=R4803)
(=R5031/3)(-R5031/4)
minmax
straddles tephra; ident uncertainmaxminmax
charcoal in distal tephraunderlies Ruru Pass Tephra (ref 58)underlies Ruru Pass Tephra (ref 58)
see ref 32minmax
compressed contam. samplemaxminmaxminmax
straddles tephra? too young
maxmin
straddles tephra (too young)sample in ignimbrite
max (coarse roots from WK352)max (fine peat residue from WK351)
mincontaminated
in sand beneath ash
sample in Ok Tephra
minmax
N78/542residue of N77/553extract of N77/553
N77/553in underlying paleosol
95% prob. >43,700
Nairnmax (heavily diluted)
min (contam.)max (contam.)max (contam.)min (contam.)
rootlets from WK939-942min (in paleo on Rm - max for Ma)
boiled in waterboiled in water
extract of NZ6028washed hot NaOH
hot NaOH
extract from hot NaOH
(Continued on next page)
108
[Continued from previous page)
New Zealand Journal of Geology and Geophysics, 1990, Vol. 33
Tephraformation
RotomaRotomaRotomaRotomaRotomaRotomaRotomaRotomaRotomaRotomaRotomaRotomaRotomaRotomaRotomaRotomaRotomaRotomaRotomaRotomaRotomaRotomaRotomaRotomaRotomaRotomaRotomaRotomaRotomaRotomaRotomaRotomaRotomaRotomaRotoruaRotomaRotoruaRotoruaRotoruaRotoruaRotoruaRotoruaRotoruaRotoruaRotoruaRotoruaTaupoTaupoTaupoTaupoTaupoTaupoTaupoTaupoTaupoTaupoTaupoTaupoTaupoTaupoTaupoTaupoTaupoTaupoTaupoTaupoTaupoTaupoTaupoTaupoTaupoTaupoTaupoTaupoTaupoTaupoTaupoTaupoTaupoTaupoTaupoTaupoTaupoTaupoTaupoTaupoTaupoTaupo
Lab
NZNZNZNZNZNZNZNZNZNZNZNZWKWKWKWKWKWKWKWKWKWKWKWKWKWKWKWKWKWKWKWKWKNZNZNZNZNZWKWKWKWKWKWKWKWKWKNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZWKWKWKWK
C14Number
603460356036603763106362637163856399641067536761229493494495522523548611705706711932933934935936937938
12701293131911861187161541834185235236511512529530572573
1502134
373882
158159160161162163164165168170172173174175176183502503524525869
1059106015483121553156105611701374427482215424928
1015
Age(yrB.P.)
8,7548,5108,5959,5098,9048,6107,4068,7598,6968,2338,6628,3737,6505,4407,3807,5608,3708,3508,0305,5107,5207,9208,0007,7209,8209,8907,5608,5208,5608,5308,5108,3108,240
13,15012,35013,4506,650
12,81012,90012,60013,45012,80013,30012,95012,65012,3501,8901,8201,9701,9201,7801,8002,0401,7601,7501,3001,7801,8301,8401,8901,9001,9801,8001,8001,7501,8001,8501,9601,8401,7701,9001,7752,1011,9951,8702,0901,8401,6801,8901,7901,7351,6001,7951,8501,7302,0401,8701,690
Stddeviation
5311152
2814152
13552
1025152
11316017080
10090
100200
7013013017070
21018070808080
10011070
300220250
0580310230120150110110230210
5015015015060705080808080705070704050
10050
100100707070607575606060507070656555556060506080
Sampletype
CECECRERERREGPrPfPGGGPGGGPGGPWWWPPPCCCC
cGGGG
MPPGGPCCCCC
CWCWWCCC
wwwcccccccpp
wwwpp
cpcPW
wpSEpGW
cp
Assessedvalue
1113113111113332113322222221111112213112112233111211211311111111111111112211131222112311
References
zzzzzzzzzzzz
16,2527,1616,2716,27
16,25,1216,25,12
16,2516
16,2516,2516,25
101010101010106464644040
21,35,36zz
16,2516,25
16,12,2516,25
1616
16,2516,25
I14,814,814
14,814,814,814,814,8
814,814,814,814,814,8
14,8,4314,814,814,814,814,814,814,89,399,399,399,3939
37,39,937,39,956,7,21
55z2020cg59
16,25,28,1216,26
fd
Collector
Lowe, GreenRogers, Lowe, HoggRogers, Lowe, HoggRogers, Lowe, Hogg
Lowe, GreenLowe, Green
Lowe, Green, HendyShaw
Lowe, Hendy, OuelletLowe, Hendy, OuelletLowe, Hendy, OuelletGreen, Lowe, HoggGreen, Lowe, HoggGreen, Lowe, HoggGreen, Lowe, HoggGreen, Lowe, HoggGreen, Lowe, HoggGreen, Lowe, Hoggde Lange, Championde Lange, Rosenbergde Lange, Rosenberg
ToppingTopping
NairnGohGoh
Lowe, GreenLowe, GreenLowe, GreenLowe, Green
Lowe, Hogg, LaneLowe, Hogg, Lane
Lowe, Green, HendyLowe, Green, Hendy
WigleyBaumgart
TaylorTaylor
SchofieldSchofieldBanwell
Grant-TaylorGrant-Taylor
CameronHealyHealyHealyHealyHealy
VucetichGregg
Vucetich, CrossHealy, ThompsonHealy, Thompson
HealyHealyGibbsPullarPullarPullarPullarPullar
Pullar, KohnPullar, Kohn
PullarWilson
HullHull
SingletonClarkson
Comments
hot NaOHextract hot NaOH
Na4PO7extract Na4PO7
residue Na4PO7extract Na4PO7residue Na4PO7extract Na4PO7residue Na4PO7residue Na4PO7extract Na4PO7
min (reworked sed. not adjacent to tephra)min (coarse roots from WK494: contam.)
min (fine peat residue of WK493: contam.)min (?contam.)
maxmin
min (reworked sed not adjacent to tephra)min (sample not adjacent to tephra)
min (sed. rate low)max (sed. rate low)
straddles tephraminmaxmaxmin
underlies tephrawithin tephra
overlies tephrastraddles tephra
maxmin
beneath ?Rrin tephra overlying ?Rr
minmax (too young?)
maxmin (thick sample)
max (tephra ident. uncertain)min (tephra ident. uncertain)
max (sed reworked)min (sed reworked)
max
water sorted
log in cave
not adjacent to tephra
doubtful strat.
minmax
stump below Tp
minmax
min (?too young)
sample surrounds NZ6511tree in situ
3 cm slice straddles tephraseeds from peat
Ota, Beanland, Bern/man minLowe, Green
McCabe, Lowe, HendyLowe
Lowe, Newnham, Lowe
wood in mud buried by Tp
min
[Continued on next page)
Froggatt & Lowe—L. QuaL tephra formations, N.Z. 109
{Continued from previous page)
Tephraformation
TaupoTaupoTe RereTe RereTuhuaTuhuaTuhuaTuhuaTuhuaTuhuaTuhuaTuhuaTuhuaTuhuaTuhuaTuhuaTuhuaWaimihiaWaimihiaWaimihiaWaimihiaWaimihiaWaimihiaWaimihiaWaimihiaWaimihiaWaimihiaWaimihiaWaimihiaWaimihiaWaimihiaWaimihiaWaimihiaWaimihiaWaimihiaWaiohauWaiohauWaiohauWaiohauWaiohauWaiohauWaiohauWaiohauWaiohauWaiohauWaiohauWaiohauWaiohauWaiohauWhakaipoWhakaipoWhakaipoWhakaipoWhakaipoWhakaipoWhakaipoWhakaipoWhakaipoWhakaipoWhakaipoWhakaipoWhakaipoWhakaipoWhakataneWhakataneWhakataneWhakataneWhakataneWhakataneWhakataneWhakataneWhakataneWhakataneWhakataneWhakataneWhakataneWhakataneWhakataneWhakataneWhakataneWhakataneWhakataneWhakataneWhakataneWhakataneWhakataneWhakataneWhakataneWhakatane
Lab
WKWKNZNZNZWKWKWKWKWKWKWKWKWKWKWKWKGAKNZNZNZNZNZNZNZNZNZNZNZWKWKWKWKWKWKNZNZNZWKWKWKWKWKWKWKWKWKWKWKNZNZNZNZNZNZNZWKWKWKWKWKWKWKNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZNZWKWKWKWKWKWKWKWKWK
C14Number
10161094523
517133377
106214241242243244505525
101913171318
104612
179180289504505
10611062394767027237
498499500610
10321259568878
1135233234515516531574575708709714716171177182184
107010712740
506507537538
101714411442426
1066107211371198124713581946316131623948394943054306430743084930496497501610611660662
13331334
Age(yrB.P.)
1,7901,800
20,70021,500
5,3706,3406,2806,2106,0706,4406,7106,0605,8005,8005,2806,1306,4402,9203,4403,4203,1503,4003,1703,4403,2703,1303,2803,5903,5803,2502,9103,0403,6603,8703,940
11,25011,10011,80012,20012,50012,45012,30012,80011,70011,80010,22011,57011,84011,9902,6502,5302,8002,4002,6702,7302,5203,0102,0102,5602,8602,9002,6702,7105,0855,1803,2006,3905,0506,1904,6904,9104,8005,2104,6004,6404,8304,8804,9405,0005,0904,4904,5304,8603,6605,5104,8504,2604,9904,770
Stddeviation
8050
450450
541907070808080809070
130100120220
707090
10080806565
110707070605070
11070
20021015023019020019011027023016013034023015070
1008050606570806060
1107080
1008065
12010070
120705080909090908080
100606070707080
140110110
Sampletype
PWCCP
CWPGPPPPGGPPP
SHCCCWPPWWPPPPPrPfPPPCWCGGGGPGGGGGGWCCCPPCGGGGPPPCcpMCMCCPPPPCCCCWPPPPPGGPP
Assessedvalue
11213111113112311211111111121222322112111131132112212111131121121332311111111112111331111
References Collector
dJ.624436
8,571
16,1516,25,28
16,1516,1516,1516,1516,2516,25
d646454
8,14,458,14,398,14,45
89,39,4539,45,99,37,399,37,39
19h
4723,27,16
27,1627,16
16bb
39,9,3,4539,9,45
3912,16,2512,16,2512,16,2512,16,25
1616,2516,2516,2516,2516,2516,258,14
39,8,1439,8,14
8,149,4536z
16,2516,2516,2516,25
dII
9,2339,23,9,38
39,939,45,23
z39,45,2323,7,56313,34
2323
19,2319,2335,3436,3436,34
3636
23,27,1623,27,1623,27,16
1616
23,16,2523,16,25
6464
Lowe, Newnham, Lowe
Comments
maxMurray in situ tree trunk in Taupo Pumice alluvium
Vucetich, PullarNairnHarrisBuck
Hogg, Lowe, GaylorLowe, GreenHogg, LoweHogg, LoweHogg, LoweHogg, Lowe
Lowe, Green, HendyLowe, Green
Lowe, Newnham, Lowede Lange, Rosenbergde Lange, Rosenberg
BaumgartHealyHealyElder
Pullar, KohnPullar, Kohn
HoworthAllowayRogers
Rogers, Lowe, HoggRogers, Lowe, HoggRogers, Lowe, Hogg
misident. as Ok (ref. 36)underlain by Kk
max (tephra idem, uncertain)
maxmaxminmax
max: thick sampleminmin
max: also min for Ma (thick sample)min (sample not adjacent to tephra)
minmax
shells under tephra
minmaxmaxminmin
max: thick samplemaxmax
min (coarse roots from WK500)min (fine peat residue from WK 499)
Shaw max (sample not adjacent to tephra; also min for WAllowayAlloway
ColePullar
Pullar, BirrellLowe, GreenLowe, GreenLowe, GreenLowe, Green
Lowe, Hogg, LaneLowe, Green, HendyLowe, Green, HendyLowe, Hendy, OuelletLowe, Hendy, OuelletLowe, Hendy, OuelletLowe, Hendy, Ouellet
CrossHealyHealyGibbsPullarPullarNairn
Lowe, Green, HendyLowe, Green, HendyLowe, Green, HendyLowe, Green, Hendy
Lowe, Newnham, LoweWigley, EdwardsWigley, Edwards
HealyPullar, Pain
PullarPullar, Kohn min: i
max: 1 cm slice (? too old)max: 1 cm slice (? too old)
sample in Rkminmaxmaxmin
straddles tephra (ident. uncertain)maxmin
min (too young - ?low sed. rate)maxminmax
strat. position uncertainmay be Mp or Wo
identity uncertainminmax
maxmin, too young?
minmax
straddles tephra; ident. uncertainminmax
uncertain strat.max
min onlyjnreliable as section reworked (ref. 18,22)
tephra ident. uncertainPullar, Kohn max: unreliable as section reworked (refs. 18,22)Healy, Nairn
NairnNeallNeall
HoworthHoworth
NairnNairnNairnNairn
Jackson, NairnRogers, Lowe, HoggRogers, Lowe, HoggRogers, Lowe, Hogg
ShawShaw
Lowe, Hendy, OuelletLowe, Hendy, Ouellet
de Lange, Crowcroft, Gilmourde Lange, Crowcroft, Gilmour
in flow
min (also max for Hm)maxminmax
wood submerged by lakemin (also max for Hm)min (also max for Hm)
maxmin (sample not adjacent to tephra)max (sample not adjacent to tephra)
maxmin (also max for Hm)
minmax