earlytertiarytectonicsand mountain building episodesoi/historical geology pdf/fyrirlestur 4 - early...

Early Tertiary Tectonics andmountain building episodes

Jarðsaga 2

- Saga Lífs og Jarðar -Ólafur Ingólfsson

The World as we know it – largely a productof Cenozoic tectonics and volcanism...

http://denali.gsfc.nasa.gov/dtam/gtam/

Mountain building (orogenic and volcanic) in process

Volcanism and the opening up of the North Atlantic

• During Cretaceous times, N America, Greenland, and Eurasia were part of a common land mass. Early in the Cenozoic, about 60 MY ago, sea-floor spreading began between Greenland and Europe.

• Continued sea-floor spreading between NorthAmerica and Greenland led to opening of Baffin Bay. Volcanism on western Greenland,

• Greenland acted as an independent plate during the early Cenozoic. Thick basalt plateaus built up in eastern Greenland, western Scotland, northern Ireland and the Faeroes

http://www.bgr.de/b324/vulkanismus/e_vulkanismus.htm

Cretaceous-Tertiarybasalts in Arctic Canada and northern Greenland

Early Tertiary volcanism on central West Greenland

Hyaloclastite breccias and lava flows of the Vaigat Formation on the south coast of Nuussuaq. Cretaceous and Paleocene sandstones and shales are present below the volcanic rocks. The cliff is about 1300 m high. Photo: Asger K. Pedersen, Geological Museum, Copenhagen.

Tertiary basalt plateau, Disko Island

Tertiarybasalts, East

GreenlandIn East Greenland earlyTertiary volcanic rockscrop out between lati-tudes 68o and c. 75o N. South of Scoresby Sund/Kangertittivaq (c. 70o N) plateau basalts cover an extensive region of c. 65 000 km2

Flood basalts in Greenland

Major Tertiary intrusive centres in

East Grennland

http://www.geus.dk/program-areas/raw-materials-greenl-map/greenland/gr-map/nh04_42s-uk.htm

Basalt dykes, East Greenland

An early Tertiary dike inArchean gneiss, Scoresby Sund area, E Greenland

A Tertiary dike swarm, ScoresbySund area, East Greenland

NorthAtlantic/Iceland

Hotspot

Circles indicate hypothesisedlocations of an Icelandic mantle plume at the times indicated in MY.

http://www.norvol.hi.is/html_i/geol_i/intro/geo1.html

Land bridge over“Iceland”...

The Tertiary biota of Iceland is closely related to themodern Eastern DeciduousForests of N America. Flora and fauna used the dynamic land bridge between North America and Europe via Greenland-”Iceland” as a migration route during the Paleogene. This land bridge emerged due to hotspot activity on the Mid Atlantic ridge in connection with the opening of the N Atlantic.

http://www.mantleplumes.org/Iceland2.html

Early Tertiaryland bridge

across “Iceland”

Plate reconstruction to60 Ma with simplifiedseafloor. The main diketrend in the BritishVolcanic Province schematically shown to extend to the West Greenland magmatic area

Tertiary basalts in Ireland

60 MY ago the Antrim area, Ireland, was subject tointense volcanic activity. There were three periods of volcanic activity which resulted in the flows, known as the Lower, Middle and Upper Basalts. It is the Middle Basalts rocks which forms the columns of the Giants Causeway.

...and Scotland

Staffa: Fingal's Cave and the columnarjointing in Tertiary volcanic flows

In early Tertiary, a volcanic chain ran down what is now the west coastof Scotland. The islands of Skye, Rum, Mull, Arran and St. Kilda, alongwith the Ardnamurchan Peninsula were all volcanic centres (above sea level). Although the volcanoes themselves no longer remain apparent, their lava flows and their eroded internal structures are obvious in the geology of Scotland.

Three series of plateaux basalts on the Faeroe Islands

There was extensive volcanism onthe Faeroe Islands during theperiod 63-54 MY. The Tertiarybasalts on the Faeroe Islands are divided into three series, the Lower-, Middle- and Upper series.

Thick Cenozoicsediments on top of

the basalt pileThe possibility for “striking it rich” and finding oil on the Faeroe Island shelf has led to extensive geophysical surveying and drilling.

Denmark wasa sedimentary

basin......below sea level untilMiocene. Thick de-posits of limestones (Paleocene) and clays (Eocene-Oligocene).

The Fur Formation

Volcanic ash beds of late Paleocene-Eocene age accumu-lated in the Fur Formation, N Denmark. This formation isfamous for its fossils, volcanic ash beds, and economic uses. The ash has similar geochemistry to plateau basalts of the Faeroes-East Greenland province

North SeaOil...

North Sea oil and gas hasbeen generated fromdeeply-buried mudstonesource rocks. Commercialpetroleum reservoirs occurin almost every sedimentarysuccession ranging in age from ca 410-36 MY. Sandstone reservoirs of Paleogene age are estimated to contain about 20% of the oil province’s proven hydrocarbon reserves

The Early Tertiary Laramide Orogeny

The Laramide Orogeny started in the Late Cretaceous and continuedinto Oligocene, The Alpine Orogeny started in early Eocene and continued into Miocene

Tectonic maps of N America and the

N Atlantic

The Laramide Orogeny

The Laramide Orogeny• The Laramide orogeny was a 30 millionyear period of mountain building inwestern N America that started in the Late Cretaceous, 70 MY ago, and ended in the Late Paleogene 40 MY ago. • The major feature that was createdby this orogeny was the RockyMountains. Evidence of the Laramide orogeny is present from Mexico to Alaska.

CretaceousPaleogeography

The Cretaceous paleogeo-graphy reflected a largeinland sea, the last timesuch a sea would exist inNorth America. The eastand south parts of theU.S. were very broad, low-lying terranes, whereas the largest mountain ranges of the Mesozoic in the west existed in the Cretaceous.

Early Tertiarypaleogography

In the Early Cenozoic,the subduction continuedalong the west coast, producing some igneousrocks, such as those at Devil's Tower NM in Wyoming. The Rocky Mountains region was dominated by the fold and thrust belt of the Laramide Orogeny.

Laramide Orogeny At the end of the Cretace-ous and through the earlyCenozoic, the Laramideorogeny, a huge deformat-ional event, reached fromthe west coast deep into thecontinent to the RockyMountains and Great Plains. Extensive thrusting of Mesozoic and older rocks on top of younger rocks occur-red throughout the Rocky Mountains, as well as broad warping of the continental basement (uplifting the Black Hills of South Dakota).

Laramide Orogeny– very complex

tectonicsThe Laramide orogenyoriginally was a poly-phase Late Cretaceous-Oligocene orogeny, consisting of manydisparate pulses of deformation that varied in intensity and age from place to place in western North America.

http://element.ess.ucla.edu/publications/1998_Laramide/1998_Laramide.htm

Laramide Orogeny andsedimentary basins

As the Rocky Mountains are uplifting, basins form betweenmajor uplifts. Huge lakes fill the basins during the Eocene.

A Rocky Mts transect

Uplifted blocks and down-dropped basins in central western USA. Veryhuge lake deposits (Green River Formation). Beginning of Yellowstone volcanism (a mantle plume underneath the American West)

The Lewis Thrust FaultA 160-200 km long thrust fault, formed 75-60 MY ago

The Lewis thrust fault. The whitePaleozoic limestone has been thrust over the brown Mesozoic shales

Rocky Mts – still in the makingThe cause of the Laramide Orogeny is still debated, andmay have been due to collision of an oceanic terrane tothe west, or an nearly flat-dipping subduction zone that extended deformation deep into the continental interior.In the middle Cenozoic, the “Laramide Orogeny RockyMts” would be eroded down, only to be rejuvenated inthe last 30 MY by the change in tectonic setting thatoccurred along the west coast, when the spreadingcenter and subduction zone collided off the west coast, changing the plate boundary to the transform fault system of the San Andreas. Recent uplift and formation of the Sierra Nevada, Basin and Range, Colorado Plateau and modern Rocky Mountains occurred after this change in plate tectonic setting along the western margin.

Japan – a product of Cenozoictectonic events

http://www.eorc.jaxa.jp/en/imgdata/topics/2004/tp040513.html

...and so is Indonesia

Tectonic activity in Eurasia

Early to middle Tertiary was a period of intense tectonic activity in Eurasia

The AlpineOrogeny

The Alpine Orogeny was a mountain-building event thataffected southern Europe and the Mediterranean regionduring the early-middle Tertiary Period. The Alpineorogeny produced intense metamorphism of preexistingrocks, crumpling of rock strata, and uplift accompanied by both normal and thrust faulting. It was responsible for the elevation of the present Alps, and for the uplifting of plateaus in the Balkan Peninsula and in Corsica and Sardinia.

The Alps seen from space

Collision of the African and Eurasian Plates

In the late Cretaceous period, the African and Eurasionplates began to converge, closing the Tethys Ocean basin. The Mediterranean sea is remnants of this ancient ocean.

Very complex tectonics

There are three major geomorphicalsettings within the Mediterranean basin:

• Areas with stable margin characteristics;

• Areas with unstable convergent margin charactericstics;

• Areas with extensional margin (rifting) characteristics.

The Mediterranean basin is a location of an interconti-nental interplate system; with compressional and extensional events occurring within close proximity.

Mediterrean volcanic activity and earthquakes

All of the volcanic and seismic activity in the Mediter-ranean area is related to one or more of these processes; subduction, extension, or other tectonic events throughout the Cenozoic.

www.eorc.jaxa.jp/en/imgdata/topics/2003/tp030717.html

A continuum between the Alps and the Himalayas...

The reddishbrown landform clearly visible inthe middle of this image is a great fold structure extending to the arid highlands in Pakistan, Afghanistan, and Iran.

Raising the Himalayas

The Grand Tertiary CollisionAbout 80 million years ago, India was located roughly6,400 km south of theAsian continent, movingnorthward at a rate of about 9 cm/yr. When India rammed into Asia about 40 to 50 million years ago, its northward advance slowed by about half.

Formation of the Himalayas – 60 MY ago

Formation of the Himalayas – 40 MY ago

Formation of the Himalayas – 20 MY ago

Formation of the Himalayas – Today

Much of the uplift has occurredduring the past 10 MY

Present rate of uplift...

The Himalayas and the Tibetan Plateau to the northhave risen very rapidly. In 50 million years, peaks suchas Mt. Everest have risen to heights of more than 9 km. The impinging of the two landmasses has yet to end. The Himalayas continue to rise more than 0.5 cm a year - a growth rate of 5 km in a million years!

The isolation of Antarctica

ODP record of Antarctic cooling

Tectonic effects on climate 1Computer model experiments perfor-med to test the climate's sensitivityto mountains and high plateaus showthat plateau uplift in Tibet andwestern North America has a small effect on global temperature butcannot explain the magnitude of the mid-late Tertiary cooling trend. Plateau uplift does, however, have a significant impact on climate, including the diversion of North Hemisphere westerly winds and intensification of monsoonal circulation.

Tectonic effects on climate 2The collision of India and Asia led to the uplift of the Tibetan Plateau and the Himalayas. Whiletopography may not be enough to explain the coolingtrends, another mechanism may account for changingclimate. The uplift may have caused both an increasein the global rate of chemical erosion, as well aserode fresh minerals that are rapidly transported to lower elevations, which are warmer and moister and allow chemical weathering to happen more efficiently. Through these mechanisms, then, it has been hypothesized that the tectonically driven uplift of the Tibetan Plateau and the Himalayas is one of the causes of the post-Eocene cooling trend.

Early Tertiary tectonics greatlyeffected global environments

Oceanic circulation was strongly affected by the tectonicevents that opened up the N Atlantic, closed the Tethys Sea and drove Antarctica towards a pole-centered position

References for this lectureStanley: Earth System History. Arnold, LondonThis Dynamic Earth. http://pubs.usgs.gov/publications/text/dynamic.html

http://jan.ucc.nau.edu/~rcb7/nat.htmlhttp://thenaturalamerican.com/paleogeography.htmhttp://sciwebserver.science.mcmaster.ca/geo/faculty/boyce/3z03/Lewis_thrust/http://www.student.brynmawr.edu/students/jgage/lewis.htmlhttp://www.bbc.co.uk/beasts/changing/miocene/currents.shtmlhttp://pubs.usgs.gov/publications/text/understanding.htmlhttp://www.oberlin.edu/Geopage/projects/204projects/kolker/kolker.htmlhttp://denali.gsfc.nasa.gov/dtam/gtam/http://www.bgr.de/b324/vulkanismus/e_vulkanismus.htmhttp://www.geus.dk/program-areas/raw-materials-greenl-map/greenland/gr-map/nh04_42s-uk.htmhttp://www.eorc.jaxa.jp/en/imgdata/topics/2004/tp040513.htmhttp://www.mantleplumes.org/Iceland2.htmlhttp://element.ess.ucla.edu/publications/1998_Laramide/1998_Laramide.htmwww.eorc.jaxa.jp/en/imgdata/topics/2003/tp030717.htmlhttp://jan.ucc.nau.edu/~rcb7/globaltext2.htmlhttp://www.scotese.com/http://www.norvol.hi.is/html_i/geol_i/intro/geo1.htmlhttp://academic.emporia.edu/aberjame/tectonic/iceland/iceland.htm