Siderium

Aeonothem	Arathem	system	Age ( mya )
later	later	later
P r o t e r o z o i k u m Duration: 1959 Ma	Neoproterozoic Jungproterozoikum Duration: 459 Ma	Ediacarium	541 ⬍ 635
		Cryogenium	635 ⬍ 720
		Tonium	720 ⬍ 1000
	Mesoproterozoic Mittelproterozoikum Duration: 600 Ma	Stenium	1000 ⬍ 1200
		Ectasium	1200 ⬍ 1400
		Calymmium	1400 ⬍ 1600
	Paleoproterozoic Altproterozoikum Duration: 900 Ma	Statherium	1600 ⬍ 1800
		Orosirium	1800 ⬍ 2050
		Rhyacium	2050 ⬍ 2300
		Siderium	2300 ⬍ 2500
earlier	earlier	earlier

The siderium is a period in the history of the earth . It represents the earliest section within the geological aeon of the Proterozoic (era Paleoproterozoic ). The beginning of the siderium is radiometrically set at 2500 million years before today and follows the end of the Archean . 2300 million years ago BP , the siderium was replaced by the rhyacium . The siderium lasted 200 million years.

Redefinition of the siderium

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

“The Siderium forms the last period of the Neo-Archean . It follows the methanium , from which it is separated by a GSSP. This GSSP is defined by the first appearance of ribbon ore in the Hamersley Basin that occurred with the Marra Mamba Iron Formation at 2,630 million years old BP . The boundary to the Paleoproterozoic and the Oxygenian Period is also marked by a GSSP, which in turn is characterized by the first appearance of glacial deposits around 2420 million years BP in the Australian Kazput Formation , Mount Bruce Supergroup . "

According to this redefinition, the Siderium therefore lasts 210 million years and extends the Archean by 80 million years to 2,420 million years BP. It is characterized by the worldwide widespread deposition of strip ores. In its course, the continental crustal growth slowed .

For a detailed presentation, see also van Kranendonk (2012).

Naming

The name is derived from the Greek σίδηρος - sideros = iron and alludes to the band ores formed around the world during this period . The creation of these ribbon ores reached its peak in the early siderium.

Stratigraphy and deposits

Significant sedimentary basins and geological formations

Hamersley Basin with Hamersley Group in Western Australia - 2715 to about 2400 million years BP
- First strip ores around 2630 million years BP in the Marra Mamba Iron Formation (Hamersley Group), Mount Bruce Supergroup in Western Australia
Transvaal Basin in South Africa - 2670 to 1900 million years BP
- Transvaal Supergroup :
  - Ghaap Group in the Griqualand West Area - 2669 ± 5 to 2450 million years BP
  - Chuniespoort Group in the Transvaal area - 2588 ± 6 to 2460 million years BP
Minas Supergroup in Eastern Brazil - 2610/2580 to 2420 million years BP
Animikie Group in the United States and Canada - 2,500 to 1,800 million years old BP
Huronian Supergroup in Eastern Ontario - 2,450 to 2,219 million years BP

Ribbon ores

Ribbon ore in the Dales Gorge, Hamersley Range

Banded iron formation ( engl. Banded iron formation or abbreviated BIF) can only at very low oxygen concentrations in the atmosphere and are formed in the water. It is believed that anaerobic algae secrete oxygen as a metabolic product, which then combined with the divalent iron contained in seawater to form iron oxide magnetite (Fe ₃ O ₄ ), which sank to the bottom. This precipitation process removed the iron from the seas, so that its previously green color disappeared. After the iron in the sea was used up by this reaction, the oxygen in the atmosphere was enriched until the current oxygen-rich level was reached. The oxygen enrichment in the atmosphere is also known as the Great Oxygen Catastrophe, which possibly caused the Paleoproterozoic glaciation that started around 2400/2300 million years BP .

Examples of ribbon ore formations:

Marra Mamba Iron Formation in Western Australia , the world's oldest ribbon ore formation - 2630 million years old
Cauê Banded Iron Formation of the Itabira Group , Minas Supergroup in Brazil - 2580 to 2420 million years BP
Asbestos Hills subgroup ( Afrikaans : Asbesheuwels ) of the Ghaap Group in South Africa - 2489 to 2480 million years ago
Penge formation of the Chuniesport Group in South Africa - around 2,480 million years BP
Brockman Iron Formation in the Hamersley Basin, Western Australia - 2,469 million years BP
Kuruman Iron Formation of the Campbellrand Subgroup in South Africa - around 2,465 million years BP

Examples of paleoproterozoic glaciation:

Kazput Formation in Western Australia - 2,420 million years old BP
Makganyene Formation of the Postmasburg Group in South Africa - diamictite - between 2,415 and 2,222 million years BP
Upper Timeball Hill Formation and Boshoek Formation of the Pretoria Group in South Africa - between 2320 and 2184 million years BP

Marine geochemistry

Rouxel et al. (2005) state a strong increase in the oxygen content of the earth's atmosphere for the period 2400 to 2300 million years BP . At about the same time (around 2300 million years BP) they observe an increase in the δ ⁵⁶ Fe values in the oceans of up to 3 ‰ compared to the Archean. To this day, the δ ⁵⁶ Fe values are no longer below - 0.5 ‰, whereas in the Archean they could still drop to - 3.5 ‰. The authors explain this fact with the establishment of oceanic depths from 2300 million years BP and an increase in sulphide precipitation compared to iron oxide precipitation .

Geodynamics - Orogeneses

East Antarctica - Mawson Craton ( Adélieland , Georg-V-Land ) - 2500 to 2420 million years BP. Retrogression from the granulite facies to the amphibolite facies . By 2440 anatectic conditions were reached and consequently monzogranodiorites , pink granites and mafic veins intruded .
In North America ( Superior Kraton ) the Algoman Orogeny (also Kenoran Orogeny) comes to an end around 2500 million years BP. Along the Great Lakes tectonic zone , the Superior Craton in the north collided with the Minnesota River Valley Terran docking in the south . After the collision, orogenic collapse and rifting occurred from 2500 million years BP .

Basement cranes

Northern Borborema Province in northeastern Brazil , Médio Coreaú Domain (MCD): Granja Complex - 2350 to 2270 million years ago. The terran consists of metatexitic orthogneiss of tonalitic and granodioritic composition ( TTG complex ), accompanied by high-grade metamorphic rocks such as kinzigites , charnockites and enderbites .

Central Brazilian Shield

Bacajá Domain : 2359 million years BP
Tapajόs Parima Province :
- Uatumã-Anauá Domain : 2354 million years BP
- Tapajόs Domain : 2483 to 2380 million years BP

Guyana Shield , Central Area: 2350 million years BP

West Africa Craton , Ivory Coast : 2,312 million years BP

Magmatism

Around 2500 to 2475 million years BP the tholeiitic and komatiitic Mistassini gang swarm invades the superior craton . With a surface area of more than 70,000 square kilometers, it can be classified as a Large Igneous Province (LIP for short). Heaman (1994) found the intrusion age to be 2470 million years BP.
According to Heaman (1995), it is followed by the Matachewan gang swarm between 2473 and 2446 million years BP (Fahrig and West dated 2470 to 2450 million years BP). It also represents a LIP and, at 250,000 square kilometers, is almost four times the size of the Mistassini gang swarm, with which it can be genetically linked. He intruded the superior craton in the area between Lake Superior and James Bay .
Around 2,410 million years BP, the Gangschar intrusion of the Widgiemooltha Dyke Suite into the Yilgarn Kraton takes place . Only insignificantly later, around 2408 million years BP, the Sebangwa Poort dykes intrude into the Zimbabwe craton . A possible neighborhood of the two cratons is suspected.

Meteorite crater

The oldest known meteorite crater of Suavjärvi was possibly formed in Karelia around 2,400 million years BP .

literature

James G. Ogg: Status on Divisions of the International Geologic Time Scale. Archived from the original on September 29, 2007. (PDF) In: Lethaia . 37, 2004, pp. 183-199. doi : 10.1080 / 00241160410006492 .
Kenneth A. Plumb: New Precambrian time scale. In: Episodes , 14 (2), Beijing 1991, pp. 134-140, ISSN 0705-3797 .

Web links

International Stratigraphic Chart 2009 (PDF; 485 kB)

Individual evidence

^ Felix M. Gradstein et al .: On the Geologic Time Scale . In: Newsletters on Stratigraphy . tape 45/2 , 2012, p. 171-188 .
^ M. Van Kranendonk: The Precambrian: the Archean and Proterozoic Eons . In: Gradstein et al. (Ed.): The Geologic Time Scale 2012 . Elsevier Publ. Co., 2012.
↑ James F. Kasting, Shuehi Ono: Paleoclimates: The First Two Billion Years . 2006.
↑ Olivier J. Rouxel et al: Iron Isotope Constraints on the Archaean and Paleoproterozoic Ocean Redox State . In: Science . tape 307 (5712) , 2005, pp. 1088-1091 .
↑ G. Duclaux, ao: Superimposed Neoarchaean and Paleoproterozoic tectonics in the Terre Adélie Craton (East Antarctica): Evidence from Th – U – Pb ages on monazite and 40Ar / 39Ar ages . In: Precambrian Research . 2008, p. 23 .
↑ TJS Santos, AH Fetter, PC Hackspacher, WRV Schmus, JA Nogueira Neto: Neoproterozoic tectonic and magmatic episodes in the NW sector of the Borborema Province, NE Brazil, during assembly of western Gondwana . In: Journal of South American Earth Sciences . tape 25 , 2008, p. 271-284 .
↑ LM Heaman: 2.45 Ga global mafic magmatism: Earth's oldest superplume? In: Eighth International Conference on Geochronology, Cosmochronology & Isotope Geology, Program with Abstracts, US Geol. Surv. Circular 1107 . Berkeley, California 1994, pp. 132 .
↑ Heaman, LM: U-Pb dating of mafic rocks: past, present and future (abstract), Program with Abstracts . In: Geol. Assoc. Can./Mineral. Assoc. Can. 20, A43, 1995.
^ WF Fahrig, TD West: Diabase dyke swarms of the Canadian shield, Map 1627A . Geological Survey of Canada, Ottawa, ON 1986.
^ AV Smirnov, among others: Trading partners: Tectonic ancestry of southern Africa and western Australia, in Archean supercratons Vaalbara and Zimgarn . In: Precambrian Research . tape 224 , 2013, p. 11-12 .

[1] Felix M. Gradstein et al .: On the Geologic Time Scale . In: Newsletters on Stratigraphy . tape 45/2 , 2012, p. 171-188 .

[2] M. Van Kranendonk: The Precambrian: the Archean and Proterozoic Eons . In: Gradstein et al. (Ed.): The Geologic Time Scale 2012 . Elsevier Publ. Co., 2012.

[3] James F. Kasting, Shuehi Ono: Paleoclimates: The First Two Billion Years . 2006.

[4] Olivier J. Rouxel et al: Iron Isotope Constraints on the Archaean and Paleoproterozoic Ocean Redox State . In: Science . tape 307 (5712) , 2005, pp. 1088-1091 .

[5] G. Duclaux, ao: Superimposed Neoarchaean and Paleoproterozoic tectonics in the Terre Adélie Craton (East Antarctica): Evidence from Th – U – Pb ages on monazite and 40Ar / 39Ar ages . In: Precambrian Research . 2008, p. 23 .

[6] TJS Santos, AH Fetter, PC Hackspacher, WRV Schmus, JA Nogueira Neto: Neoproterozoic tectonic and magmatic episodes in the NW sector of the Borborema Province, NE Brazil, during assembly of western Gondwana . In: Journal of South American Earth Sciences . tape 25 , 2008, p. 271-284 .

[7] LM Heaman: 2.45 Ga global mafic magmatism: Earth's oldest superplume? In: Eighth International Conference on Geochronology, Cosmochronology & Isotope Geology, Program with Abstracts, US Geol. Surv. Circular 1107 . Berkeley, California 1994, pp. 132 .

[8] Heaman, LM: U-Pb dating of mafic rocks: past, present and future (abstract), Program with Abstracts . In: Geol. Assoc. Can./Mineral. Assoc. Can. 20, A43, 1995.

[9] WF Fahrig, TD West: Diabase dyke swarms of the Canadian shield, Map 1627A . Geological Survey of Canada, Ottawa, ON 1986.

[10] AV Smirnov, among others: Trading partners: Tectonic ancestry of southern Africa and western Australia, in Archean supercratons Vaalbara and Zimgarn . In: Precambrian Research . tape 224 , 2013, p. 11-12 .