Cryogenium

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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 cryogenium is the second period of the Neoproterozoic . Its beginning is set at approximately 720 million years BP and its end at 635 million years BP. In the evolution of organisms it probably played an important but so far largely not understood role.

The Cryogenium follows the Tonium and is replaced by the Ediacarium , in which there was a great development of multicellular organisms .

Naming

The name Cryogenium is derived from the ancient Greek κρύος (kryos) meaning cold or ice and γένεσις (genesis) meaning birth, origin . The name alludes to the almost global glaciation of the earth at that time.

Events during the cryogenium

Ice ages

The Sturtische (720 to 658 million years BP) and Marino Ice Age (655 to 635 million years BP) with almost global icing (see “ Snowball Earth ”) fall into the period of the cryogenium . However, the extent of the icing has been put into perspective by more recent research results and the critical voices are increasing. There were probably ice-free areas at the equator. Many newer models are now more of a "Slushball Earth" (from the English translated Schneematscherdball ) from.

The subsequent Gaskiers Ice Age (approx. 579 million years BP) already belongs to the Ediacarium. It is possible that the Sturtic Ice Age was preceded by glaciation, the so-called Kaigas Ice Age around 750 million years BP, which is not so clearly documented.

The glacial deposits of the cryogenium are predominantly diamictites or proximal, proglacial sediments that were deposited in passive rift trenches during the breakup of Rodinia. They can be found on many of the paleo- and micro-continents of the time, such as western North America , China , Australia , West Africa , South America and Oman . In the sequence of layers, the glacial sediments are characterized by their abrupt onset, but also by their sudden disappearance. Usually they are of so-called Hutkarbonaten (English cap carbonates completed), insert the unusual sedimentological, geochemical and isotopic ratios of the day. The hat carbonates (mostly limestone, but also dolomites) were formed when the sea level rose after the glaciation ended.
The two icings characteristic of the cryogenium were accompanied by strong, positive and negative excursions of the δ 13 C values.
After almost 1,000 million years of absence, the ribbon ores returned, and in their wake phosphorites and manganese ores . Black shale was also deposited around the world during the cryogenium . The sulphate content of the sea water was low.

Even before the beginning of the cryogenium, the supercontinent Rodinia began to break apart around 750 million years BP and the surrounding ocean Mirovia was gradually closing. The supercontinent Pannotia with the ocean Panthalassa was supposed to emerge as a new formation during the Ediacarium . The causes of the global glaciation are probably due to this breakup of Rodinia, as the continent fragments drifted towards the equator and accumulated there. At the same time, the rift process had led to the continent fragments being lifted out. Taken together, both effects ultimately increased the albedo and, at the same time, the erosion rate, thus triggering global cooling by lowering the carbon dioxide concentration in the atmosphere. The beginning cooling in turn reduced the biological activity.

Meteorite impact

The impact crater of Strangways in the Northern Territory of Australia falls during the cryogenic period . The impact took place 646 ± 42 million years ago, the diameter of the crater was more than 24, possibly even up to 40 kilometers.

Biological development

The amoeba genus Arcella under the microscope

So-called “vase-shaped microfossils” are available from the cryogenium, which with some probability can be related to the envelopes of Arcellinida , a group of the amoeba ( thecamoeba ) that carry shell . Contrary to earlier assumptions, the group was already present in the fossil record before the Sturtic glaciation. Microfossils are also from the acritarcha , a problematic group that is often interpreted as cysts or permanent stages of unknown unicellular eukaryotes. Multicellular algae , as demonstrated by the famous find of Bangiomorpha pubescens, must have existed a long time before, even if there are no unambiguous fossil finds from the cryogenium itself. The discovery of a fossil called Otavia antiqua , which its discoverers assigned to the sponges , would also date the origin of the multicellular animals to the cryogenium or an earlier epoch; the interpretation as a sponge is denied by other researchers, so that the existence of Metazoa in the cryogenium is uncertain. Finds such as puzzling, disk-like fossils from China, described as "Jinxian Biota" could possibly represent eukaryotic multicellular organisms, but their assignment is completely uncertain.

Key Cryogenium Microfossils:

stratigraphy

Significant sedimentary basins and geological formations

literature

Web links

Individual evidence

  1. ↑ Chart . International Commission on Stratigraphy. Archived from the original on January 13, 2017. Retrieved February 14, 2017.
  2. ^ Emmanuelle Arnaud: Giant cross-beds in the Neoproterozoic Port Askaig Formation, Scotland: implications for snowball Earth. In: Sedimentary Geology , 165 (1-2), Amsterdam 2004, pp. 155-174, ISSN  0037-0738 , DOI: 10.1016 / j.sedgeo.2003.11.015
  3. ^ Małgorzata Moczydłowska: The Ediacaran microbiota and the survival of Snowball Earth conditions. In: Precambrian Research , 167 (1-2): Amsterdam 2008, pp. 1-15, ISSN  0301-9268 , DOI: 10.1016 / j.precamres.2008.06.008
  4. Jump up ↑ Judy P. Pu, Samuel A. Bowring, Jahandar Ramezani, Paul Myrow, Timothy D. Raub, Ed Landing, Andrea Mills, Eben Hodgin, Francis A. MacDonald: Dodging snowballs: Geochronology of the Gaskiers glaciation and the first appearance of the Ediacaran biota . In: Geology . tape 44 , no. 11 , 2016, p. 955 , doi : 10.1130 / G38284.1 .
  5. ↑ Macdonald, FA et al: Calibrating the Cryogenian . In: Science . tape 327 , 2010, pp. 1241-1243 , doi : 10.1126 / science.1183325 .
  6. ↑ James, NP et al .: Later Neoproterozoic cap carbonates: Mackenzie Mountains, northwestern Canada: precipitation and global glacial meltdown . In: Canadian Journal of Earth Sciences . tape 38 , 2001, p. 1229-1262 .
  7. ↑ Kirschvink, JL et al .: Paleoproterozoic snowball Earth: Extreme climatic and geochemical global change and its biological consequences . In: Proceedings of the National Academy of Sciences, USA . tape 97 , 2000, pp. 1400-1405 .
  8. ^ Condie, KC et al .: Precambrian superplumes and supercontinents: a record in black shales, carbon isotopes and paleoclimates? In: Precambrian Research . tape 106 , 2001, pp. 239-260 .
  9. ↑ Hurtgen, MT et al .: The sulfur isotopic composition of Neoproterozoic seawater sulfate: implications for a snowball earth? In: Earth and Planetary Science Letters . tape 203 , 2002, pp. 413-429 .
  10. ↑ Van Kranendonk, MJ: Chapter 16. A chronostratigraphic division of the Precambrian: Possibilities and Challenges . In: The Geologic Time Scale 2012 . Elsevier BV, 2012, doi : 10.1016 / B978-0-444-59425-9.00016-0 .
  11. ↑ Daniel JG Lahr, Anush Kosakyan, Enrique Lara, Edward AD Mitchell, Luana Morais, Alfredo L. Porfirio-Sousa, Giulia M. Ribeiro, Alexander K. Tice, Tomas Panek, Seungho Kang, Matthew W. Brown (2019): Phylogenomics and Morphological Reconstruction of Arcellinida Testate Amoebae Highlight Diversity of Microbial Eukaryotes in the Neoproterozoic. Current Biology (in press) doi: 10.1016 / j.cub.2019.01.078 .
  12. ↑ Timothy M. Gibson, Patrick M. Shih, Vivien M. Cumming, Woodward W. Fischer, Peter W. Crockford, Malcolm SW Hodgskiss, Sarah Wörndle, Robert A. Creaser, Robert H. Rainbird, Thomas M. Skulski, Galen P. Halverson (2017): Precise age of Bangiomorpha pubescens dates the origin of eukaryotic photosynthesis. Geology 46 (2): 135-138. doi: 10.1130 / G39829.1
  13. ↑ Brain, CK et al .: The first animals: approx. 760-million-year-old sponge-like fossils from Namibia . In: S. Afr. J. Sci. tape 108 (8) , 2012, p. 1-8 , doi : 10.4102 / sajs.v108i1 / 2.658 .
  14. ↑ Jonathan B. Antcliffe, Richard HT Callow, Martin D. Brasier (2014): Giving the early fossil record of sponges a squeeze. Biological Reviews of the Cambridge Philosophical Society 89 (4): 972-1004. doi: 10.1111 / brv.12090 .
  15. ↑ Xingliang Zhang, Hong Hua, Joachim Reitner (2006): A new type of Precambrian megascopic fossils: the Jinxian biota from northeastern China. Facies 52: 169-181. doi: 10.1007 / s10347-005-0027-z
  16. ↑ Cui Luo, Maoyan Zhu, Joachim Reitner (2016): The Jinxian Biota revisited: taphonomy and body plan of the Neoproterozoic discoid fossils from the southern Liaodong Peninsula, North China. Paleontological Journal 90 (2): 205-224. doi: 10.1007 / s12542-016-0289-5