karst in mariovo

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- - , 12-15 IX2013HILLY- MOUNTAIN - AREAS PROBLEMS AND PERSPECTIVES, Ohrid, 12-15 IX 2013

551.435.8(497.775)

KARST IN MARIOVO EXTENSION,

CHARACTERISTICS AND IMPORTANCE

Marjan TEMOVSKIDoctorate student, University of Nova Gorica, Slovenia,Vlado Stojanoski 37a, Prilep, Macedonia, [email protected]

ABSTRACT

This paper will present the general characteristics of karst in Mariovo, a hilly mountainous area in thesouthern part of Republic of Macedonia, its extension, surface morphology as well as speleogenesis and karstwaters. Previous results will be combined with new research on surface karst, caves and karst waters in this area.Karst rocks present 16% of Mariovo area, where due to complex geological and geomorphological characteristicsome specific karst features developed. Number of caves has been explored in the past few years, most of whichhave been studied, giving new insight in to the general karst development. Also new karst springs weredocumented, such as Gugjakovski Izvori (the largest spring along the river course of Crna Reka), which give

further insight to the karst hydrogeology of the area. The importance of karst areas in Mariovo is mostly due to anumber of specific karst features, mostly connected to thermal speleogenesis, such as Provalata Cave wheresulfuric acid was involved in its formation. This cave is also the first dated cave in Macedonia, and only thesecond 40Ar/39Ar dated sulfuric acid cave in Europe. Mariovo, especially the eastern part (where karst is found)is now mostly depopulated area, leaving karst to have no immediate impact on people today, although someagriculture is still present. Nevertheless, projected future dam Galite is covering karst areas along Crna Rekavalley, and proper understanding of karst in this area will be important for future management of this artificialreservoir. Also, given the scarce water resources in Mariovo, large springs such as Gugjakovski Izvori are animportant resource.

Keywords: Mariovo, karst, caves, karst springs

INTRODUCTION

Mariovo is a geographical and historical region in the southern part of Republic ofMacedonia (Stojmilov, 1984). It is hilly to mountainous area, with a long and complexgeomorphological and geological evolution. Most of the area is part of one largemorphological unit Mariovo Basin, while the eastern border is located further to the eastalong Blanica River and along mountain ridges in the eastern part of Dren Mountain.

Karst areas in Mariovo occupy 16% of the area mostly located in the central and easternparts. Previous studies on karst terrains in this area have been very scarce, mostly due to thegenerally harsh, hardly accessible and depopulated terrains. Small notes on the karst inMariovo are given by Manakovik & Andonovski (1984) as part of the geomorphology of

Mariovo. They only address the extension of carbonate rocks, and describe some karst surfacefeatures such as karren and dry valleys. published first results aboutcave Provalata (named Gulabinka in the paper), giving morphometric information and notingthe presence of gypsum deposits. Although contributing the presence of gypsum todissolution of the marble by hydrothermal waters enriched with H2S, they consider the cave asfossil ponor cave. Speleological exploration in this area was also carried by cavers, locatingand mapping generally caves which were previously known to the local population. In thewestern part caving clubs SK Zlatovrv from Prilep and Ursus Speleos from Skopje have explored Provalata Cave and cave ivovska Propast (Propast Provala). In the eastern part,cavers from PSD Orle from Kavadarci have also documented some caves, mostly in the 1960s

and 1970s, describing location, general size and also mapping some of them.

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Cave. Basic physical and chemical analysis of karst waters was done at the Center for PublicHealth in Prilep. For detailed descriptions of the analytical methods see Temovski et al.(2013). Morphometric analyses on karst surface were done on Aster GDEM data, version 2(Meyer et al., 2012) using Spatial Analyst tool in ESRI ArcGIS 10.1.

KARST EXTENSION

Karst rocks in Mariovo occupy 16% of the total area (Tab.1), which is more than the 12%area that karst rocks cover in Republic of Macedonia (Temovski, 2012. They are located on

both sides of the border between the Pelagonian Massif and the Vardar Zone, two majortectonic units in Macedonia, and are generally distributed in two stripes with NNW-SSEdirection, one along the eastern edge of the Pelagonian Massif, and the other in the western

part of the Vardar Zone.

Table 1. Extension of karst rock outcrops in Mariovo (Geological data after Dumurdanov et al., 1976)

Age Rock type Area (km2)

% of total

karst areaPrecambrian Dolomitic marble 37.6 22.3Precambrian Calcitic marble 2.1 1.2Cambrian Calcitic marble 7.3 4.4Triassic Marbly limestone and dolomite 71.3 42.4Cretaceous (Turonian) Limestone 0.3 0.2Cretaceous (Senonian) Limestone 32.6 19.4Quaternary (Pleistocene) Travertine + carbonate conglomerates 16.9 10.1

TOTAL AREA of karst rocks 168.2 100.0

MARIOVO area (km2) 1053.4

Karst rocks in MARIOVO (%) 16.0

Karst rocks include Precambrian dolomitic and calcitic marbles; Cambrian calciticmarbles; Triassic marbly limestones and dolomites; Cretaceous (Turonian and Senonian)limestones; and Pleistocene travertines (Dumurdanov et al., 1976). Triassic limestones anddolomites have the largest surface extension (42.4%), located in the eastern part on Dren,Kozjak and Kouf mountains, deeply incised by the valleys of Crna Reka and Blanica Riverwith its tributaries. Precambrian dolomitic marbles are the second largest karst rock outcrop(22.3%), located in a continuous stripe along the eastern edge of the Pelagonian Massif. Tothe east they are covered by Precambrian calcitic marbles, then Cambrian calcitic marbles,and are separated from the overlying large Senonian limestone series (19.4%) with clasticrocks (also Senonian). This thick carbonate section (Precambrian, Cambrian and Senonian),

generally dipping to the ENE which has some impermeable layers (Cambrian schists;Senonian sandstones, shales and conglomerates) continues further to the south in Greece andto the north in the neighbor Raec Basin. The youngest karst rocks are Pleistocene travertinedeposits (10.1%), part of Mariovo Basin deposits (Mariovo Formation; Dumurdanov et al.,2003, 2004). They are mostly located as a large outcrop between Manastir and Beitevillages, but travertine deposits can also be found along Crna Reka valley between Vrpskoand Gugjakovo villages. The travertine deposits are mostly composed of tufaceous limestonesand tufa, at places overlying carbonate breccia-conglomerates composed of marble andlimestone fragments. Also small outcrops of Turonian limestones are found as lenses in theclastic Turonian series on Kouf Mountain.

The real extension of karst rocks in the area is larger than the surface extension, with some

areas buried by pyroclastic deposits from Kouf/Kozjak volcanism, and others also coveredby older sediments (ex. Turonian clastic deposits overthrusted onto Senonian limestones).

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NATURAL RESOURCES AND LAND USE IN HILLY-MOUNTAIN AREAS

KARST SURFACE

Karst terrains in Mariovo have mainly fluviokarst surface morphology, with deep allogenicthrough valleys, steep dry valleys on valley sides and lack of dolines or bigger karstdepressions as a general characteristic.

Ford & Williams (2007) indicate three main factors which prevent doline development: 1)very high vertical conductivity through-out the vadose zone; 2) spatially uniform and densevertical permeability; and steep (>20) hillsides. The lack of doline development in Mariovois a result of a combination of these factors. Morphometric analysis of terrain slope on karstterrains gave average slope value of 22.8, with most of the small slopes (


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Figure 3. Distribution of slopes in karst terrains

In the large travertine deposits on Manastir-Beite Plateau, which have the largest flatareas, as small slopes were present since the exposure of the rocks after the draining of theMariovo Lake (primary - depositional low slopes), development of dolines would be

expected. Nevertheless this is not the case, with only (spatially) large and very shallow, hardlydetectable, depressions developed on them. Although slopes are favorable for dolinedevelopment, the reason for the lack of doline development may be the high primary porosityof the travertines. This created high vertical conductivity in the vadose zone (after the incisionof Bututica and Crna Reka) preventing development of depressions in the epikarst water table,and with that preventing focused flow and dissolution necessary for development of dolines.

CAVES

In Mariovo karst 18 caves have been documented (Fig.1; Tab.2), with the longest carbonate conglomerates, and more than half of the caves being longer than 100m. Thedeepest cave is ivovska Propast (-115m), a complex system of shafts developed along threesets of fractures.

From the studied caves, both hypogenic and epigenic speleogenesis were identified.Hypogenic speleogenesis was documented in three areas: Melnica (Buturica River), Podot(Crna Reka) and Kouf karst areas. Caves were developed by dissolution of carbonate rocksdue to cooling effect of rising thermal waters (Dublyansky, 2000). Deeply circulatingmeteoric waters were heated as a result of increased geothermal gradient likely connected toKouf-Kozjak volcanism. This hydrothermal hypogenic speleogenesis, due to lithological orgeochemical factors, locally is accompanied with specific processes such as ghost-rock

weathering (Quinif, 1999) in the Precambrian dolomitic marbles of Melnica and Podot

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localities, as well as Triassic dolomites in Allchar ore deposit (Kouf), and sulfuric acidspeleogenesis (Egemeier, 1981; Palmer, 2013) as a second phase in Provalata Cave, Melnica.

Table 2. Caves in Mariovo karst

No. Name Synonym Length Depth Rock age Rock type

1 600+ +17 Pleistocene Carbonate conglomerates2 ivovska Propast

PropastProvala

-115 Senonian Limestone

3 Provalata Gulabinka 230 -24 Cambrian Marble4 Vodna Pe 226+ -25 Triassic Marbly limestone5 Peti 202 -38 Senonian Limestone

6 Kari Podot 199 +12Precambrian;Pleistocene

dolomitic marble; alluvium,tufaceous limestone

7 Peterski Kamen Trlo 173+ +63 Triassic Marbly limestone8 Galika Petera 120 -20 Triassic Marbly limestone9 Vodena Petera 106 -3 Triassic Marbly limestone10 Podot 2 P14 103+ -18 Pleistocene Tufaceous limestone11 97 -8 Pleistocene Carbonate conglomerates

12 Podot 1 P13 64 -14 Pleistocene Tufaceous limestone13 Marina Dupka 26 -11 Senonian Limestone14 Boeva Petera 19 Triassic Marbly limestone15 Dupkite 1 14 Senonian Limestone16 Stankova Petera 11 Triassic Marbly limestone17 Radina Dupka 8 -5 Senonian Limestone18 Dupkite 2 4 Senonian Limestone

Provalata Cave is a 230m long, 24m deep cave, located in the superimposed valley ofButurica River in Melnica area. The cave has a ramiform passage pattern, with cupolas andsolution pockets as most common morphological features. Based on characteristics anddistribution of morphology and deposits, two distinct speleogenetic phases were identified inthe cave (Temovski et al., 2013): the first by thermal CO2 rich waters; the second by sulfuricacid dissolution; separated by complete infilling of cave passages with pyroclastic-derivedclays.

In the first phase (Pliocene-Early Pleistocene?) phreatic morphologies (passages, cupolas)were formed by dissolution of marbles due to cooling of rising thermal carbonated waters;later covered with thick calcite crust after shift to shallower phreatic environment. These

passages were then completely filled with clay deposits originating from the pyroclasticsediments of Mariovo Formation (Early Pleistocene). Incision of Buturica River after drainingof Mariovo Lake lowered the water table and allowed removal of clay sediments. Introductionof H2S in the thermal waters (likely connected to the nearby coal basin) started the second

(sulfuric acid) speleogenetic phase, with rapid dissolution of calcite crust and marble hostrock due to condensation corrosion by sulfuric vapors and producing replacement gypsumdeposits. At contact with clay deposits, sulfuric acid produced alunite, jarosite andnatroalunite, which were dated with 40Ar/39Ar method to 1.6 Ma (alunite) and 1.46 Ma(jarosite). This allowed to fix the timing of the draining of Mariovo Lake, sometime between1.8 Ma (last layers of tephra found in the travertine layers deposited in lacustrine environmentas end part of Mariovo formation; and volcanic activity in Kozjak Mt. dated to 4.0 0.2 to 1.8 0.1 Ma, Kolios et al., 1999), and 1.6 Ma (maximum age of cave alunite formed afterdraining of Mariovo Lake and incision of Buturica River).

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Figure 3. Speleogenetic phases in Provalata Cave (modified after Temovski et al., 2013)

Kari Podot Cave is 200m long horizontal cave, located in Kari Podot terrace (Podotlocality in Crna Reka valley), developed in Precambrian dolomitic marbles and Pleistocenealluvial and travertine deposits. Its development is connected to ghost-rock weathering in thedolomitic marbles by slowly rising thermal waters, with backflooding of Crna Reka providingthe necessary high energy waters removing the dolomitic sand alterite, with some redepositionof dolomitic sand with silicate sands and clays also inside the cave (Temovski, 2013).

conglomerates in Peta Hill, Melnica. It has a branchwork plan pattern, with irregular passageoutlines typical of a high porosity host rocks. Its widespread small scale morphology ofcupolas and pockets, as wall as calcite (and aragonite) crust covering such morphologies inthe upper parts of the cave and having overprinted secondary pockets, combined with thethermal karstification documented in the nearby Gumnite locality, as well as Provalata Cave,suggest possible origin due to hydrothermal speleogenesis accompanied with condensationcorrosion.

Hydrothermal speleogenesis is documented also in Kouf area, with two thermal springsdischarging at the contact of carbonate rocks with impermeable schist rocks. In the Allcharore deposit, hydrothermal speleogenesis has played important role in creating porosity in the

dolomite and limestone rocks which was later used as host for the deposition of ore minerals.In dolomite rocks this was accompanied with ghost-rock weathering (sandingdecalcification as described by Percival & Radtke, 1994).

Most of the karst terrains in the studied area have normal epigenic cave development,receiving allogenic or autogenic recharge from the adjacent surface. Epigenic speleogenesis inMariovo karst is connected mostly to lowering of base level (per descensum speleogenesis)due to incision of Crna Reka and its tributaries in Pleistocene, following the draining ofMariovo Lake; with epigenic caves also developed due to rise of base level (per ascensumspeleogenesis) connected to periods of river aggradation in Pleistocene and/or Pliocene fillingof paleo-valleys.

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importance, as well as representing a valuable natural heritage and yielding important waterresources.

Both hypogenic and epigenic karst features have great scientific importance. The closeproximity of Provalata Cave to Mariovo coal deposits, which might be the potential source ofH2S for the second (sulfuric acid) speleogenetic phase registered in the cave, presents an

opportunity for further studies which might contribute to better understanding of the sulfuricacid speleogenesis and the possible various hypogenic speleogenetic environments that canoccur. Also, the ghost-rock weathering process identified in the Precambrian dolomiticmarbles, as well as in the Triassic dolomitic, here connected to hydrothermal speleogenesis,contributes further to the understanding of the ghost-rock weathering and phantom cavedevelopment in hypogenic settings. Especially the dolomitic marbles with the Kari PodotCave present a possibility for more detail studies of this process and its importance onincreasing porosity on otherwise less karstifiable rocks. Caves in the area can also be used for

paleogeographic reconstructions of the Macedonian Neogene-Quaternary lake system, as wasthe case with the evolution of Provalata Cave, used to determine the possible timing of thedraining of Mariovo Lake.

Specific cave minerals such as alunite, jarosite, natroalunite documented in Provalata caveare first such minerals identified from Macedonian caves. Alunite and jarosite were also usedfor 40Ar/39Ar dating, the first dating of a cave in Republic of Macedonia, and the second40Ar/39Ar dating of sulfuric cave in Europe, after Kraushhle in Austria (Temovski et al.,2013). Together with the cave fauna, which is still not studied, they represent an importantnatural heritage.

Considering that lack of water resources is one of Mariovos major problems, and most ofthe water resources in the area are connected to karst terrains, karst springs in Mariovo suchas Gugjakovski Izvori, the largest spring along the river course of Crna Reka, represent amajor water resource. Therefore further studies, protection and proper management of karstareas in Mariovo is necessary, especially connected to future revitalizations of the area, andconstruction of the artificial reservoir Galite.

CONCLUSIONS

Karst terrains represent 16% of the total surface area in Mariovo, and are characterizedwith mostly fluviokarst surface features, with developed karst underground. The fluviokarstsurface is generally characterized with deep allogenic through valleys (Crna Reka, Blanica,Buturica), steep dry valleys on valley sides and lack of dolines or bigger karst depressions.Karst evolution in the area has been strongly influenced by the incision of river valleys Pre-Pliocene, and in Pleistocene, while during the Pliocene and Early Pleistocene the lower areas

were covered by lacustrine and fluvial deposits, as well as pyroclastic deposits connected tothe Kozjak-Kouf volcanism to the south. Epigenic cave development has been connectedwith the changes of base level due to incision or aggradation in the river valleys and Mariovo

basin. Hypogenic caves were formed by hydrothermal speleogenesis due to cooling effect ofrising deeply circulating meteoric waters, heated due to increased geothermal gradient likelyconnected to Kouf-Kozjak volcanism. At places, due to lithological or geochemical factors,hydrothermal hypogenic speleogenesis is accompanied with specific processes, such as ghost-rock weathering in the Precambrian dolomitic marbles of Melnica and Podot localities, aswell as Triassic dolomites in Allchar ore deposit (Kouf), and sulfuric acid speleogenesis inProvalata Cave, Melnica. Mariovo karst has great scientific importance due to the specific

processes, such as sulfuric acid speleogenesis and ghost-rock weathering, as well as

possibilities to study the paleogeography of the Macedonian Neogene-Quaternary lakesystem, and the per-ascensum model of speleogenesis connected to the aggradations in river

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valleys. Specific minerals, such as alunite, jarosite, natroalunite in Provalata Cave, which isthe first dated cave in Republic of Macedonia, as well as cave fauna yet to be studied, are asignificant natural heritage, while karst waters represent an important water resource in anarea with a general lack of water resources.

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PERCIVAL J.C., RADTKE, A.S. (1994): Sedimentary-rock-hosted disseminated gold mineralization in theAlsar District, Macedonia. Canad. Mineralogist 32, 649-665QUINIF Y. (1999): Fantmisation, cryptoaltrationet altration sur roche nue, le triptyque de la karstification, Actes du colloque europen Karst 99, 159-164.SD PEONI (2005): Cave map of Zivovska Propast (not published)SK ZLATOVRV (2011-2013): Cave maps of Melni e (not published)STOJMILOV A. (1984): Geografska poloba. In: Mariovo - fakultet, Skopje, 9-15.TEMOVSKI M. (2012): Povrinska rasprostranetost na karstnite karpi vo Republika Makedonija (Extension ofkarst rock outcrops in Republic of Macedonia). Geografski razgledi, Skopje, 46, 21-35.TEMOVSKI M. (2013): Phantom speleogenesis in a thermal environment, 21st International KarstologicalSchool Hypogene speleogenesis, 10-14.06.2013, Postojna, Slovenia (poster presentation)TEMOVSKI M., AUDRA P., MIHEVC A., SPANGENBERG J.E., POLYAK V., McINTOSH W., BIGOT J-Y(2013): Hypogenic origin of Provalata Cave, Republic of Macedonia: a distinct case of successive thermal

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