Paleoproterozoic

Last updated
Paleoproterozoic Era
2500–1600 million years ago
Key events in the Paleoproterozoic
-2500 
-2400 
-2300 
-2200 
-2100 
-2000 
-1900 
-1800 
-1700 
-1600 
Proterozoic
Archean
An approximate timescale of key Paleoproterozoic events.
Axis scale: millions of years ago.

The Paleoproterozoic Era ( /pæliˌprtərəˈzɪk-/ ; [1] [2] , also spelled Palaeoproterozoic), spanning the time period from 2,500 to 1,600 million years ago (2.5–1.6  Ga), is the first of the three sub-divisions (eras) of the Proterozoic Eon. The Paleoproterozoic is also the longest era of the Earth's geological history. It was during this era that the continents first stabilized.

Contents

Paleontological evidence suggests that the Earth's rotational rate during this era resulted in 20-hour days ~1.8 billion years ago, implying a total of ~450 days per year. [3]

Paleoatmosphere

Before the enormous increase in atmospheric oxygen, almost all existing lifeforms were anaerobic organisms, i.e., their metabolism was based upon a form of cellular respiration that did not require oxygen. Free oxygen in large amounts is toxic to most anaerobic organisms. Consequently, the majority of the anaerobic lifeforms on Earth died when the atmospheric free-oxygen levels soared in an extinction event called the Great Oxidation Event. The only lifeforms that survived were either those resistant to the oxidizing and poisonous effects of oxygen, or those sequestered in oxygen-free environments. The sudden increase of atmospheric free oxygen and the ensuing extinction of the vulnerable lifeforms is widely considered to be the one of the first and most significant mass extinctions in the history of the Earth. [4]

Emergence of Eukarya

Many crown node eukaryotes (from which the modern-day eukaryotic lineages would have arisen)—or the divergences that imply them between various groups of eukaryotes—have been ostensibly dated to around the time of the Paleoproterozoic era. [5] [6] While there is some debate as to the exact period at which Eukaryotes evolved, [7] [8] current understanding places it somewhere in this period. [9] [10]

Geological events

During this era, the earliest global-scale continent-continent collision belts developed.

These continent and mountain building events are represented by the 2.1–2.0 Ga Trans-Amazonian and Eburnean orogens in South America and West Africa; the ~2.0 Ga Limpopo Belt in southern Africa; the 1.9–1.8 Ga Trans-Hudson, Penokean, Taltson–Thelon, Wopmay, Ungava and Torngat orogens in North America, the 1.9–1.8 Ga Nagssugtoqidain Orogen in Greenland; the 1.9–1.8 Ga Kola–Karelia, Svecofennian, Volhyn-Central Russian, and Pachelma orogens in Baltica (Eastern Europe); the 1.9–1.8 Ga Akitkan Orogen in Siberia; the ~1.95 Ga Khondalite Belt and ~1.85 Ga Trans-North China Orogen in North China.

These continental collision belts are interpreted as having resulted from one or more 2.0–1.8 Ga global-scale collision events that then led to the assembly of a Proterozoic supercontinent named Columbia or Nuna. [11] [12]

Felsic volcanism in what is now northern Sweden led to the formation of the Kiruna and Arvidsjaur porphyries. [13]

The lithospheric mantle of Patagonia's oldest blocks formed. [14]

See also

Related Research Articles

The Precambrian is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the Phanerozoic eon, which is named after Cambria, the Latinised name for Wales, where rocks from this age were first studied. The Precambrian accounts for 88% of the Earth's geologic time.

Rodinia Hypothetical neoproterozoic supercontinent from between about a billion to about three quarters of a billion years ago

Rodinia was a Neoproterozoic supercontinent that assembled 1.1–0.9 billion years ago and broke up 750–633 million years ago. Valentine & Moores 1970 were probably the first to recognise a Precambrian supercontinent, which they named 'Pangaea I'. It was renamed 'Rodinia' by McMenamin & McMenamin 1990 who also were the first to produce a reconstruction and propose a temporal framework for the supercontinent.

The Proterozoic is a geological eon spanning the time from the appearance of oxygen in Earth's atmosphere to just before the proliferation of complex life on the Earth. The name Proterozoic combines the two forms of ultimately Greek origin: protero- meaning "former, earlier", and -zoic, a suffix related to zoe "life". The Proterozoic Eon extended from 2500 mya to 541 mya, and is the most recent part of the Precambrian "supereon." The Proterozoic is the longest eon of the Earth's geologic time scale and it is subdivided into three geologic eras : the Paleoproterozoic, Mesoproterozoic, and Neoproterozoic.

Kenorland Hypothetical Neoarchaean supercontinent from about 2.8 billion years ago

Kenorland was one of the earliest known supercontinents on Earth. It is thought to have formed during the Neoarchaean Era c. 2.72 billion years ago (2.78Ga) by the accretion of Neoarchaean cratons and the formation of new continental crust. It comprised what later became Laurentia, Baltica, Western Australia and Kalaharia. It also formed a substantial part of Nena, the supercontinent associated with the Sudbury Basin Impact.

Columbia (supercontinent) Ancient supercontinent of approximately 2,500 to 1,500 million years ago

Columbia, also known as Nuna and Hudsonland, was one of Earth's ancient supercontinents. It was first proposed by Rogers & Santosh 2002 and is thought to have existed approximately 2,500 to 1,500 million years ago in the Paleoproterozoic Era. Zhao et al. 2002 proposed that the assembly of the supercontinent Columbia was completed by global-scale collisional events during 2.1–1.8 Ga.

Arctica or Arctida was an ancient continent which formed approximately 2.565 billion years ago in the Neoarchean era. It was made of Archaean cratons, including the Siberian Craton, with its Anabar/Aldan shields in Siberia, and the Slave, Wyoming, Superior, and North Atlantic cratons in North America. Arctica was named by Rogers 1996 because the Arctic Ocean formed by the separation of the North American and Siberian cratons. Russian geologists writing in English call the continent "Arctida" since it was given that name in 1987, alternatively the Hyperborean craton, in reference to the hyperboreans in Greek mythology.

Atlantica An ancient continent formed during the Proterozoic about 2 billion years ago

Atlantica is an ancient continent that formed during the Proterozoic about 2,000 million years ago from various 2 Ga cratons located in what is now West Africa and eastern South America. The name, introduced by Rogers 1996, was chosen because the continent opened up to form the South Atlantic Ocean.

History of Earth The development of planet Earth from its formation to the present day

The history of Earth concerns the development of planet Earth from its formation to the present day. Nearly all branches of natural science have contributed to understanding of the main events of Earth's past, characterized by constant geological change and biological evolution.

Supercontinent cycle The quasi-periodic aggregation and dispersal of Earths continental crust

The supercontinent cycle is the quasi-periodic aggregation and dispersal of Earth's continental crust. There are varying opinions as to whether the amount of continental crust is increasing, decreasing, or staying about the same, but it is agreed that the Earth's crust is constantly being reconfigured. One complete supercontinent cycle is said to take 300 to 500 million years. Continental collision makes fewer and larger continents while rifting makes more and smaller continents.

Great Oxidation Event Paleoproterozoic surge in atmospheric oxygen

The Great Oxidation Event (GOE), sometimes also called the Great Oxygenation Event, Oxygen Catastrophe, Oxygen Crisis, Oxygen Holocaust, or Oxygen Revolution, was a time period when the Earth's atmosphere and the shallow ocean experienced a rise in oxygen, approximately 2.4 billion years ago (2.4 Ga) to 2.1–2.0 Ga during the Paleoproterozoic era. Geological, isotopic, and chemical evidence suggests that biologically induced molecular oxygen (dioxygen, O2) started to accumulate in Earth's atmosphere and changed Earth's atmosphere from a weakly reducing atmosphere to an oxidizing atmosphere, causing almost all life on Earth to go extinct. The causes of the event remain unclear.

Vaalbara Archaean supercontinent from about 3.6 to 2.7 billion years ago

Vaalbara was an Archean supercontinent consisting of the Kaapvaal Craton and the Pilbara Craton. E. S. Cheney derived the name from the last four letters of each craton's name. The two cratons consist of crust dating from 2.7 to 3.6 Gya, which would make Vaalbara one of Earth's earliest supercontinents.

Kaapvaal Craton Archaean craton, possibly part of the Vaalbara supercontinent

The Kaapvaal Craton, along with the Pilbara Craton of Western Australia, are the only remaining areas of pristine 3.6–2.5 Ga crust on Earth. Similarities of rock records from both these cratons, especially of the overlying late Archean sequences, suggest that they were once part of the Vaalbara supercontinent.

North China Craton A continental crustal block in northeast China, Inner Mongolia, the Yellow Sea, and North Korea

The North China Craton is a continental crustal block with one of Earth's most complete and complex records of igneous, sedimentary and metamorphic processes. It is located in northeast China, Inner Mongolia, the Yellow Sea, and North Korea. The term craton designates this as a piece of continent that is stable, buoyant and rigid. Basic properties of the cratonic crust include being thick, relatively cold when compared to other regions, and low density. The North China Craton is an ancient craton, which experienced a long period of stability and fitted the definition of a craton well. However, the North China Craton later experienced destruction of some of its deeper parts (decratonization), which means that this piece of continent is no longer as stable.

Trans-Hudson orogeny mountain-building event in North America

The Trans-Hudson orogeny or Trans-Hudsonian orogeny was the major mountain building event (orogeny) that formed the Precambrian Canadian Shield, the North American Craton, and the forging of the initial North American continent. It gave rise to the Trans-Hudson orogen (THO), or Trans-Hudson Orogen Transect (THOT), which is the largest Paleoproterozoic orogenic belt in the world. It consists of a network of belts that were formed by Proterozoic crustal accretion and the collision of pre-existing Archean continents. The event occurred 2.0-1.8 billion years ago.

Wyoming Craton A craton in the west-central United States and western Canada

The Wyoming Craton is a craton in the west-central United States and western Canada – more specifically, in Montana, Wyoming, southern Alberta, southern Saskatchewan, and parts of northern Utah. Also called the Wyoming Province, it is the initial core of the continental crust of North America.

Great Bear Magmatic Zone

The Great Bear Magmatic Zone (GBMZ) is a Paleoproterozoic (1.875–1.86 Ga) multi-collisional orogenic belt of which 100 km × 400 km is exposed in the northwestern Canadian Shield east of Great Bear Lake, Northwest Territories.

The Boring Billion, otherwise referred to as the Barren Billion, the Dullest Time in Earth's History, and Earth’s Middle Ages, is the time period between 1.8 and 0.8 billion years ago (Gya) spanning the middle Proterozoic eon, characterized by more or less tectonic stability, climatic stasis, and stalled evolution. It is bordered by two different oxygenation and glacial events, but the Boring Billion itself had very low oxygen levels and no evidence of glaciation. The oceans may have been oxygen- and nutrient-poor and sulfidic (euxinia), populated by mainly anoxygenic cyanobacteria, a type of photosynthetic bacteria which uses hydrogen sulfide (H2S) instead of water and produces sulfur instead of oxygen. This is known as a Canfield ocean. Such composition may have caused the oceans to be black- or milky-turquoise instead of blue.

Wopmay orogen

The Wopmay orogen is a Paleoproterozoic orogenic belt in northern Canada which formed during the collision between the Hottah terrane, a continental magmatic arc, and the Archean Slave Craton at about 1.88 Ga. The collision lead to the short-lived Calderian orogeny. The formation was named for Wilfrid Reid "Wop" May, OBE, DFC, a Canadian flying ace in the First World War and a leading post-war aviator.

East Antarctic Shield A cratonic rock body which makes up most of the continent Antarctica

The East Antarctic Shield or Craton is a cratonic rock body that covers 10.2 million square kilometers or roughly 73% of the continent of Antarctica. The shield is almost entirely buried by the East Antarctic Ice Sheet that has an average thickness of 2200 meters but reaches up to 4700 meters in some locations. East Antarctica is separated from West Antarctica by the 100–300 kilometer wide Transantarctic Mountains, which span nearly 3,500 kilometers from the Weddell Sea to the Ross Sea. The East Antarctic Shield is then divided into an extensive central craton that occupies most of the continental interior and various other marginal cratons that are exposed along the coast.

Huangling Complex

Huangling Complex represents a group of rock units appear in the middle of Yangtze Block in South China, distributed across Yixingshan, Zigui, Huangling and Yichang counties. The group of rock involves nonconformity that sedimentary rocks overlie the metamorphic basement. It is a 73-km long, asymmetrical dome-shaped anticline with axial plane orientating in north-south direction. It has a steeper west flank and a gentler east flank. Basically, there are three tectonic units from the anticline core to the rim, including Archean to Paleoproterozoic metamorphic basement, Neoproterozoic to Jurassic sedimentary rocks and Cretaceous fluvial deposit sedimentary cover. The northern part of the core is mainly tonalite-trondhjemite-gneiss (TTG) and Cretaceous sedimentary rock, it is called the Archean Kongling Complex. The middle of the core is mainly the Neoproterozoic granitoid. The southern part of the core is the Neoproterozoic potassium granite. Two basins are situated on the western and eastern flanks of the core respectively, including the Zigui basin and Dangyang basin. Both basins are synforms while Zigui basin has a larger extent of folding. Yuanan Graben and Jingmen Graben are found within Dangyang Basin area. Huangling Complex is an important area that helps unravel the tectonic history of South China Craton because it has well-exposed layers of rock units from Archean basement rock to Cretaceous sedimentary rock cover due to the erosion of the anticline.

References

  1. "palaeo-". Oxford Dictionaries . Oxford University Press . Retrieved 2016-01-20. "Proterozoic". Oxford Dictionaries . Oxford University Press . Retrieved 2016-01-20.
  2. "Proterozoic". Merriam-Webster Dictionary .
  3. Pannella, Giorgio (1972). "Paleontological evidence on the Earth's rotational history since early precambrian". Astrophysics and Space Science . 16 (2): 212. Bibcode:1972Ap&SS..16..212P. doi:10.1007/BF00642735.
  4. Margulis, Lynn; Sagan, Dorion (1997-05-29). Microcosmos: Four Billion Years of Microbial Evolution. University of California Press. ISBN   9780520210646.
  5. Hedges, S Blair; Chen, Hsiong; Kumar, Sudhir; Wang, Daniel YC; Thompson, Amanda S; Watanabe, Hidemi (2001-09-12). "A genomic timescale for the origin of eukaryotes". BMC Evolutionary Biology. 1: 4. doi:10.1186/1471-2148-1-4. ISSN   1471-2148. PMC   56995 . PMID   11580860.
  6. Hedges, S Blair; Blair, Jaime E; Venturi, Maria L; Shoe, Jason L (2004-01-28). "A molecular timescale of eukaryote evolution and the rise of complex multicellular life". BMC Evolutionary Biology. 4: 2. doi:10.1186/1471-2148-4-2. ISSN   1471-2148. PMC   341452 . PMID   15005799.
  7. Rodríguez-Trelles, Francisco; Tarrío, Rosa; Ayala, Francisco J. (2002-06-11). "A methodological bias toward overestimation of molecular evolutionary time scales". Proceedings of the National Academy of Sciences of the United States of America. 99 (12): 8112–8115. Bibcode:2002PNAS...99.8112R. doi:10.1073/pnas.122231299. ISSN   0027-8424. PMC   123029 . PMID   12060757.
  8. Stechmann, Alexandra; Cavalier-Smith, Thomas (2002-07-05). "Rooting the eukaryote tree by using a derived gene fusion". Science. 297 (5578): 89–91. Bibcode:2002Sci...297...89S. doi:10.1126/science.1071196. ISSN   1095-9203. PMID   12098695.
  9. Ayala, Francisco José; Rzhetsky, Andrey; Ayala, Francisco J. (1998-01-20). "Origin of the metazoan phyla: Molecular clocks confirm paleontological estimates". Proceedings of the National Academy of Sciences of the United States of America. 95 (2): 606–611. doi:10.1073/pnas.95.2.606. ISSN   0027-8424. PMC   18467 . PMID   9435239.
  10. Wang, D Y; Kumar, S; Hedges, S B (1999-01-22). "Divergence time estimates for the early history of animal phyla and the origin of plants, animals and fungi". Proceedings of the Royal Society B: Biological Sciences. 266 (1415): 163–171. doi:10.1098/rspb.1999.0617. PMC   1689654 . PMID   10097391.
  11. Zhao, Guochun; Cawood, Peter A; Wilde, Simon A; Sun, Min (2002). "Review of global 2.1–1.8 Ga orogens: implications for a pre-Rodinia supercontinent". Earth-Science Reviews. 59 (1–4): 125–162. Bibcode:2002ESRv...59..125Z. doi:10.1016/S0012-8252(02)00073-9.
  12. Zhao, Guochun; Sun, M.; Wilde, Simon A.; Li, S.Z. (2004). "A Paleo-Mesoproterozoic supercontinent: assembly, growth and breakup". Earth-Science Reviews. 67 (1–2): 91–123. Bibcode:2004ESRv...67...91Z. doi:10.1016/j.earscirev.2004.02.003.
  13. Lundqvist, Thomas (2009). Porfyr i Sverige: En geologisk översikt (in Swedish). pp. 24–27. ISBN   978-91-7158-960-6.
  14. Schilling, Manuel Enrique; Carlson, Richard Walter; Tassara, Andrés; Conceição, Rommulo Viveira; Berotto, Gustavo Walter; Vásquez, Manuel; Muñoz, Daniel; Jalowitzki, Tiago; Gervasoni, Fernanda; Morata, Diego (2017). "The origin of Patagonia revealed by Re-Os systematics of mantle xenoliths". Precambrian Research . 294: 15–32. Bibcode:2017PreR..294...15S. doi:10.1016/j.precamres.2017.03.008.