Jatulium

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The Jatulium the second period within the eon Proterozoic and within the era Paleoproterozoic . It follows the period of oxygen and is in turn superseded by the period of columbium . The Jatulium lasted 190 million years and fills the period from 2250 to 2060 million years BP . It partially replaces the earlier Rhyacium . However, the Jatulium has not yet been ratified by the International Commission on Stratigraphy and is therefore still unofficial (2016).

Naming

The Jatulium, English Jatulian , is derived from the Jatulischen quartzites Finland and Karelia , some of transgressive with base conglomerate over the metamorphic basement rocks of the Archean were deposited.

Redefinition of the Precambrian Periods

In the course of moving away from period boundaries determined purely by radiometry, the GSSP principle should now also be applied as far as possible in the Precambrian, according to Gradstein et al. (2012) . The periods would thus be defined on the basis of significant geological events and no longer on arbitrary, radiometric ages.

Definition of Jatulium

The lower limit of the Jatulium should be determined by a GSSP, which would come to lie at the base of the Canadian Lorrain Formation belonging to the Cobalt Group of the Huronian Supergroup . The Lorrain Formation, deposited around 2250 million years BP, marks the end of the glaciations during the Oxygenium. It covers an oxidized palaeosol the previous, at their base diamiktischen Gowganda Formation . As an alternative, the transition from the Ahmalahti formation to the Neverskrukk formation in the Petschenga greenstone belt would also be conceivable. Two GSSP locations are also being considered for the upper limit - the base of the Rooiberg Group of the Kapvaal craton in South Africa , with which voluminous magmatism sets in, or the base of the Kolasjoki Formation or the Kuetsjärvi Formation in the Pechenga greenstone belt.

meaning

Curve of the Lomagundi-Jatuli isotope excursion

Increased mantle temperatures during the Jatulian period led to increased magmatic activity (after the magmatism had almost been extinguished in the previous 250 million years) and thus to an increase in the carbon dioxide concentration in the atmosphere . In the sea there was a flourishing of the microorganisms , which caused the oxygen concentration to rise sharply through photosynthesis .

The increase in oxygen is suggested by the following geological findings:

Lomagundi Jatuli isotope excursion

During the Jatulian period, the Lomagundi-Jatuli isotope excursion occurs , which represents the world's most significant positive anomaly of the δ 13 C values in the entire history of the earth . It allows conclusions to be drawn about profound changes in the redox behavior of the world's oceans.

For the first time, cap carbonates were created , which have very high δ 13 C values ​​and cover previous glacial sediments, as well as oxidized paleo soils and continental and marine red sediments , which were created by oxidative, continental weathering.

Shallow marine, calcium- containing sulphates such as gypsum and anhydrite (from 2200 million years BP onwards, the sulphate concentration had increased due to the oxidative weathering of continental sulphides ) and manganese- rich sediments formed in the depths of the oceans .

evolution

Gabonionta, earliest form of multicellular, eukaryotic life on earth

In Jatulium around 2100 million years BP, megascopic algae with a cell nucleus ( eukaryotes ) appeared for the first time in Michigan's Negaunee Iron Formation , which is why an alternative suggestion for naming this period is eukaryum . At the same time appeared in the Francevillian Group in Gabon the francevillian biota , the first multicellular organisms .

Jatulian Group

The Jatulian Group (also Jatulian Super-horizon or Jatulium in the original sense), after which the Jatulium period was named, forms part of the Karelian Supergroup of the Baltic Shield . It was either on the leveled Archean with occasionally pronounced Angular deposited or follows in turn over the rocks of Sumiums or Saroliums . Traces of intensive chemical weathering can be seen in the rocks of the Jatulian Group (widespread regoliths , conglomerates with quartz pebbles and quartz arenites ). The Ludicovium , the Kalevium and the Vepsium then follow above the Jatulian Group .

In the area of ​​the Onega Basin , the over 500 meters thick Jatulian Group, deposited in an Epeirian sea , can be divided into the following formations (from hanging to lying):

stratigraphy

Significant sedimentary basins and geological formations

Magmatism

After a rest period of 250 to 200 million years ( crustal age gap ), enormous eruptions of basaltic magmas occurred in the interval 2220 to 2200 million years BP . Mighty flood basalts formed in South Africa and Western Australia:

In North America, equivalent intrusive rocks formed:

Increased magmatism can also be observed in India and China at this time.

Widespread granite-greenstone terranes emerged in Brazil and West Africa , which differ only insignificantly from their archaic predecessors :

  • Mineiro Belt in the south of the São Francisco Craton in central Brazil - 2230 to 2220 million years BP
  • Crixás greenstone belt in central Brazil - around 2209 million years BP
  • Birimian in West Africa - around 2229 million years BP
  • Man Kraton in West Africa Craton , West Africa - 2250 to 2000 million years BP. The craton, made up of the association TTG-gneiss / greenstone belt, consists of its archaic core of newly formed crust that was formed within an oceanic plateau - with an accretion rate that is 60% higher than in modern examples.

Geodynamics

Orogenesis

Continent collisions:

Individual evidence

  1. ^ Felix M. Gradstein et al .: On the Geologic Time Scale . In: Newsletters on Stratigraphy . tape 45/2 , 2012, p. 171-188 .
  2. ^ KC Condie, et al: Evidence and implications for a widespread magmatic shutdown for 250 Myr on Earth . In: Earth and Planetary Science Letters . tape 282 , 2009, pp. 294-298 .
  3. ↑ GD Pollack, among others: U-Th-Pb-REE systematic of organic rich shales from the 2.15 Ga Sengoma Argillite Formation, Botswana: Evidence for oxidative continental weathering during the Great Oxidation Event . In: Chemical Geology . tape 260 , 2009, p. 172-185 .
  4. ↑ T.-M. Han, B. Runnegar: Megascopic eukaryotic algae from the 2.1-billion-year-old Negaunee iron formation, Michigan . In: Science . tape 257 , 1992, pp. 232-235 .
  5. ↑ Gabonionta, the little revolutionaries of evolution. In: derstandard.at . Retrieved February 5, 2015.
  6. ↑ Gabonionta: How Mehrzeller tried to conquer the earth. In: nachrichten.at . Retrieved February 5, 2015.
  7. ↑ Rebekah Lundquist: Provenance Analysis of the Marquette Range Supergroup sedimentary rocks using U-Pb Isotope geochemistry on detrital zircons by LA-ICP-MS . In: 19th annual Keck Symposium . 2006.
  8. ^ VA Kulikov: Summary geological map of the Onega structure . In: LV Glushanin, et al. (Ed.): The Onega Paleoproterozoic structure (Geology, tectonics, deep structure and minerageny) (in Russian) . Institute of Geology, Karelian Research Center of RAS, Petrozavodsk 2011, p. 19-23 .
  9. ↑ RJ Wardle, among others: The southeastern Churchill Province: synthesis of a Paleoproterozoic transpressional orogen: Proterozoic evolution of the northeastern Canadian Shield: lithoprobe eastern Canadian Shield onshore-offshore transect . In: Canadian Journal of Earth Sciences . tape 39 , 2002, p. 639-663 .
  10. ^ VA Kulikov: Summary geological map of the Onega structure . In: LV Glushanin, et al. (Ed.): The Onega Paleoproterozoic structure (Geology, tectonics, deep structure and minerageny) (in Russian) . Institute of Geology, Karelian Research Center of RAS, Petrozavodsk 2011, p. 19-23 .
  11. ^ GV Ovchinnikova, among others: Pb-Pb age of Jatulian carbonate rocks: the Tulomozero Formation in south-eastern Karelia (in Russian) . In: Stratigr. Geol. Correlate. tape 4 , 2007, p. 20-33 .
  12. ↑ NB Philippov, among others: New geochronological data on the Koikary-Svjatnajolok and Pudozhgora gabbro-dolerite intrusive (in Russian with an English summary) . In: VI Golubev, VV Shchiptsov (ed.): Geol. Miner. Resour. Karelia . tape 10 , 2007, p. 49-68 .
  13. ↑ MA Semikhatov, including: A new stratigraphic scale for the Precambrian of the USSR (in Russian) . In: Proc. USSR Acad. Sci. Geol. Ser 4, 1991, pp. 3-16 .
  14. ^ HC Dorland: Provenance ages and timing of selected Neoarchean and Paleoproterozoic successions of the Kapvaal craton. Unpublished Ph. D. thesis . Rand Afrikaans University, Johannesburg 2004, p. 326 .
  15. ^ DM Martin, inter alia: A pre-2.2 Ga age for giant hematite ores of the Hamersley Province, Australia . In: Economic Geology . tape 93 , 1998, pp. 1084-1090 .
  16. ^ SR Noble, PC Lightfoot: U-Pb baddeleyite ages of the Kerns and Triangle Mountain intrusions, Nipissing Diabase, Ontario . In: Canadian Journal of Earth Sciences . tape 29 , 1992, pp. 1424-1429 .
  17. ↑ KI Buchan, ao: Paleomagnetismn, U-Pb chronology, and geochemistry of Marathon dykes, Superior Province, and comparison with the Fort Frances swarm . In: Canadian Journal of Earth Sciences . tape 33 , 1996, pp. 1583-1595 .
  18. ↑ CA Ávila, inter alia: Rhyacian (2.23-2.20 Ga) juvenile accretion in the southern Sao Francisco craton, Brazil: Geochemical and isotopic evidence from the Serinha magmatic suite, Mineiro belt . In: Journal of South American Earth Sciences . tape 29 , 2010, p. 464-482 .
  19. ↑ H. Jost, inter alia: A U-Pb zircon Paleoproterozoic age for the metasedimentary host rocks and gold mineralization of the Crixáas greenstone belt, Goiás, Central Brazil . In: Ore Geology Reviews . tape 37 , 2010, p. 127-139 .
  20. ↑ J.-L. Feybesse, et al: The Paleoproterozoic Ghanian province: Geodynamic model and ore controls, including regional stress modeling . In: Precambrian Research . tape 149 , 2006, pp. 149-196 .
  21. ↑ M. Lompo: Geodynamic evolution of the 2.25-2.00 Ga Paleoproterozoic rocks in the Man-Leo Shield of the West African Craton. A model of subsidence of an oceanic plateau . In: SM Reddy, et al. (Ed.): Paleoproterozoic supercontinents and Global Evolution . tape 323 . Geological Society, London, Special Publications, 2009, pp. 231-254 .