Geological era The Paleoproterozoic pron en pe l .o pro t r zo . k , also spelled Palaeoproterozoic is the first of the three sub divisions era geology eras of the Proterozoic occurring between Ma 1600 2500 . This is when the continents first stabilized. This is also when cyanobacteria evolved, a type of bacteria which uses the biochemical process of photosynthesis to produce energy and oxygen . Before the significant increase in atmospheric oxygen almost all life that existed was wikt anaerobic anaerobic , that is, the metabolism of life depended on a form of cellular respiration that did not require oxygen. Free oxygen in large amounts is poisonous to most anaerobic organism anaerobic bacteria , and at this time most life on Earth vanished. The only life that remained was either resistant to the oxidizing and poisonous effects of oxygen, or spent its life cycle in an oxygen free environment. This main event is called the oxygen catastrophe . Also the Francevillian Group Fossil Francevillian Group and Grypania fossils and the first eukaryote s appeared during this time. Paleontological evidence on the Earth s rotational history suggests that 1.8 billion years ago, there were about 450 days in a year, implying 20 hour days. ref Giorgio Pannella http www.springerlink.com content u4pl7170jr5427t6 Paleontological evidence on the Earth s rotational history since early precambrian Astrophysics and Space Science 16.2 1972 212 ref The crown eukaryotes , from which all modern day eukaryotic lineages have arisen, date back to the paleoproterozoic sub division. Also, during this time 1 bya , the latest common ancestors between the ciliate and chordate lineages probably diverged Dubious date August 2010 . During this era the earliest global scale continent continent collisional ... 2007 01 08 ref Commons category Paleoproterozoic References reflist External links http www.stratigraphy.org ... Paleoproterozoik br Paleoproterozoeg ca Paleoproterozoic de Pal oproterozoikum et Paleoproterosoikum ... more details
image North america basement rocks.png right thumb 250px North America cratons and basement rock. The Rae craton is an Archean craton located in northern Canada north of the Superior craton . Ungava Peninsula The Ungava Peninsula , situated on the northeast portion of the Canadian Shield , is where the Rae Province connects with the Superior Province. The area is composed of Archean rocks ca. 2.7 2.9 Ga from the Douglas Harbour Domain see Superior craton . The Archean rocks are overlain by Paleoproterozoic supracrustal Sequence geology sequences ca. 1.8 2.1 Ga and intrusion intruded by Paleoproterozoic diabase Dike geology dykes ca.2.0 2.2 Ga . The supracrustal rocks comprise nappe s that form part of the Ungava and Labrador Trough geology troughs . In the zone east of the Labrador Trough axis, the Paleoproterozoic deformation reworked the Archean rocks of the Douglas Harbour Domain, as well as the Paleoproterozoic diabase dykes. The metamorphic conditions which parallel the deformation increase from west to east and from middle amphibolite to granulite facies . uranium lead dating U Pb isotope analyses of zircon yield secondary ages around 1790 Ma. These results are interpreted as the age of metamorphism . They indicate reactivation of the northeastern margin of the Superior craton Superior Province during a Paleoproterozoic tectonic tectono Metamorphism metamorphic event, resulting from probable continent al collision. Madore, 2001 . See also Canadian Shield North American craton References Madore, L., and Y. Larbi. 2001 Regional structural character of the northeastern Ungava Peninsula Connection between the Rae and Superior provinces. St. John s 2001 Technical Programme SS2 Tectonic Integration of Circum Superior Orogens. Online Abstract http gac.esd.mun.ca gac 2001 seven sub program.asp?sess 98&form 10&abs no 118 Category Cratons Category Historical geology Category Geology of the Northwest Territories Category Geology of North America palaeo geo stub ... more details
The Winagami sill complex , also called the Winagami sills , is a Paleoproterozoic large igneous province of northwestern Alberta , Canada . It consists of a series of related sill geology sills that were formed between 1.89 and 1.76 million years ago. The Winagami sill complex covers an area of Convert 120000 km2 mi2 abbr on . ref http www.thefreelibrary.com Igneous rock associations in Canada 3. Large Igneous Provinces LIPs ... a0124343378 Igneous rock associations in Canada 3. Large Igneous Provinces LIPs in Canada and adjacent regions 3 Ga to Present. ref See also Portal Volcanism of Canada Volcanism of Canada Volcanism of Western Canada Volcanism of Eastern Canada Volcanism of Northern Canada References reflist Large igneous provinces Alberta geo stub Canada geology stub coord missing Alberta Category Large igneous provinces Category Volcanism of Alberta Category Paleoproterozoic volcanism Category Sills ... more details
The Matachewan hotspot was a volcano volcanic hotspot geology hotspot responsible for the creation of the large 2,500 to 2,450 million year old Matachewan dike swarm , as well as continential rift ing of the Superior craton Superior and Hearne craton Hearne craton s during the Paleoproterozoic period. See also Portal Volcanism of Canada Volcanism of Canada Volcanism of Eastern Canada Mackenzie hotspot Great Lakes Tectonic Zone References http www.mantleplumes.org WebDocuments Bleeker 20& 20Ernst 20IDC5 20paper.pdf Short lived mantle generated magmatic events and their dyke swarms The key unlocking Earth s paleogeographic record back to 2.6 Ga coord missing Ontario Category Volcanism of Ontario Category Hotspots of North America Category Paleoproterozoic volcanism Ontario geo stub Volcanology stub ... more details
Unreferenced stub auto yes date December 2009 Orphan date December 2009 Vaasa granite is a Migmatite migmatitic Paleoproterozoic garnet bearing Granite granitoid with variable amounts of gneiss ose enclaves. The name refers to occurrences at Vaasa , on the west coast of Finland . See also List of rock types DEFAULTSORT Vaasa Granite Regional geology stub Category Plutonic rocks ... more details
The Fox River Belt is a convert 300 km mi 0 abbr on long and convert 10 km mi 0 abbr on to convert 30 km mi 0 abbr on wide Paleoproterozoic geologic feature located in northern Manitoba , Canada . It consists of sedimentary rock sedimentary and mafic ultramafic igneous rock s. ref http adsabs.harvard.edu abs 2004AGUSM.V43A..08D Fractional Crystallization of Komatiitic Magma in the Proterozoic Fox River Belt Northern Manitoba ref References reflist Category Geology of Manitoba Category Proterozoic Canada geology stub ... more details
The Winnipegosis komatiite belt , also called the Winnipegosis komatiites , is a volcanic belt composed of komatiite in central Manitoba , Canada . It is part of a large igneous province surrounding much of the Superior craton called the Circum Superior Belt . ref http www.largeigneousprovinces.org May.html Ca. 1880 Ma Circum Superior LIP ref See also Portal Volcanism of Canada Volcanism of Canada Volcanism of Western Canada References reflist Category Volcanism of Manitoba Category Volcanic belts Category Paleoproterozoic volcanism Canada geology stub ... more details
Image Matachewan and Mistassini dike swarms.png thumb right Map of the Matachewan and Mistassini dike swarm s of Eastern Canada The Matachewan dike swarm is a large 2,500 to 2,450 million year old Paleoproterozoic dike swarm of Northern Ontario , Canada . It consists of basalt ic dike geology dike s that were intrude d in greenschist , granite greenstone, and metamorphosed sedimentary terrain s of the Superior craton of the Canadian Shield . ref http adsabs.harvard.edu abs 1987asee....2Q....N Petrogenesis of basalts from the Archean Matachewan Dike Swarm Superior Province of Canada ref With an area of Convert 360000 km2 mi2 abbr on , the Mistassini dike swarm stands as a large igneous province . ref http www.thefreelibrary.com Igneous rock associations in Canada 3. Large Igneous Provinces LIPs ... a0124343378 Igneous rock associations in Canada 3. Large Igneous Provinces LIPs in Canada and adjacent regions 3 Ga to Present. ref See also Portal Volcanism of Canada Matachewan hotspot Volcanism of Canada Volcanism of Eastern Canada References reflist Large igneous provinces Category Dike swarms Category Volcanism of Ontario Category Paleoproterozoic volcanism Volcanology stub ... more details
Image Matachewan and Mistassini dike swarms.png thumb right Map of the Matachewan and Mistassini dike swarms of Eastern Canada The Mistassini dike swarm is a 2.5 billion year old Paleoproterozoic dike swarm of western Quebec , Canada . It consists of mafic dike geology dikes that were intrusion intruded in the Superior craton of the Canadian Shield . With an area of Convert 100000 km2 mi2 abbr on , the Mistassini dike swarm stands as a large igneous province . ref http www.thefreelibrary.com Igneous rock associations in Canada 3. Large Igneous Provinces LIPs ... a0124343378 Igneous rock associations in Canada 3. Large Igneous Provinces LIPs in Canada and adjacent regions 3 Ga to Present. ref See also Portal Volcanism of Canada Matachewan dike swarm Volcanism of Canada Volcanism of Eastern Canada Volcanism of Northern Canada Volcanism of Western Canada References reflist Large igneous provinces Quebec geo stub Canada geology stub coord missing Quebec Category Dike swarms Category Volcanism of Quebec Category Paleoproterozoic volcanism ... more details
The Huronian glaciation extended from 2400 annum Mya to 2100 Mya, during the Siderian and Rhyacian periods of the Paleoproterozoic era, triggered by the Great Oxygenation Event oxygen catastrophe , which oxidised the atmospheric methane a greenhouse gas . It was one of the most severe and longest ice ages in geologic history, similar to the Snowball Earth ice ages that happened in the neoproterozoic era. ref name NS http www.newscientist.com article mg20527461.100 first breath earths billionyear struggle for oxygen.html First breath Earth s billion year struggle for oxygen New Scientist, 2746, 05 February 2010 by Nick Lane. A snowball period, c2.4 c2.0 Gya, triggered by the Oxygen catastrophe ref ref name Williams cite journal author Williams G.E. Schmidt P.W. title Paleomagnetism of the Paleoproterozoic Gowganda and Lorrain formations, Ontario low palaeolatitude for Huronian glaciation journal EPSL year 1997 volume 153 issue 3 pages 157 169 url http www.cosis.net abstracts EAE03 08262 EAE03 J 08262.pdf format PDF doi 10.1016 S0012 821X 97 00181 7 ref ref Evans, D. A., Beukes, N. J. & Kirschvink, J. L. 1997 Nature 386, 262 266. ref ref name Kopp cite journal author Robert E. Kopp, Joseph L. Kirschvink, Isaac A. Hilburn, and Cody Z. Nash title The Paleoproterozoic snowball Earth A climate disaster triggered by the evolution of oxygenic photosynthesis journal Proc. Natl. Acad. Sci. U.S.A. year 2005 volume 102 issue 32 pages 11131 6 url http www.pnas.org cgi reprint 0504878102v1 doi 10.1073 pnas.0504878102 pmid 16061801 pmc 1183582 ref References reflist Proterozoic Footer Ice Ages Glaciology stub DEFAULTSORT Huronian Glaciation Category Proterozoic Category Glaciology Category Ice ages Category Extinction events br Huronieg ca Glaciaci huroniana es Glaciaci n Huroniana it Glaciazione uroniana ja nn Huron istida pt Glacia o Huroniana ru ... more details
Geobox Volcanic arc name Taltson Magmatic Zone other name image North america basement rocks.png image size 280 image caption Map of cratons and basement rock of North America. The Taltson Magmatic Zone is the north south trending green line extending from the Wyoming craton in the south to the southeastern end of the Rae craton in the north. country Canada region type Regions region Alberta region1 Northwest Territories length imperial length round length orientation highest highest elevation highest lat d highest lat m highest lat s highest lat NS N highest long d highest long m highest long s highest long EW W geology geology1 period Paleoproterozoic map map size map caption The Taltson Magmatic Zone is a zone of Paleoproterozoic magma tic rocks in the Canadian Shield , extending from Northern Alberta to the Northwest Territories . The magmatic zone was formed by subduction of oceanic crust along a pre existing continental margin , creating a continental volcanic arc . See also Portal Volcanism of Canada Great Bear Magmatic Zone Volcanism of Canada Volcanism of Northern Canada Volcanism of Western Canada References reflist Category Volcanism of Alberta Category Volcanism of the Northwest Territories Category Volcanic arcs Category Paleoproterozoic volcanism NorthwestTerritories geo stub NorthernAlberta geo stub Canada geology stub ... more details
The Marathon Large Igneous Province is a Paleoproterozoic large igneous province along the southern Superior craton of Ontario , Canada , located around the northern margin of Lake Superior . It consists of three diabase dike swarm s known as Marathon, Kapuskasing and Fort Frances. The Kapuskasing and Marathon dike swarms range in age from about 2,126 to 2,101 million years old while the Fort Frances dike swarm is between 2,076 and 2,067 million years old. ref name SI http www.sciencedirect.com science? ob ArticleURL& udi B6VBP 4R3C0D0 1& user 10& coverDate 05 2F01 2F2008& rdoc 1& fmt high& orig search& sort d& docanchor &view c& searchStrId 1368463221& rerunOrigin google& acct C000050221& version 1& urlVersion 0& userid 10&md5 277ad3dabaeac8980f7bb33ae0d0189f The Paleoproterozoic Marathon Large Igneous Province New evidence for a 2.1. Ga long lived mantle plume event along the southern margin of the North American Superior Province ref A single, periodically active mantle plume was responsible for the creation of the Marathon Large Igneous Province due to the lack of apparent polar wander during the formation of the igneous province. ref name SI The large magmatic event covers an area of at least Convert 400000 km2 mi2 abbr on and the entire large igneous province was constructed in 60 million years. ref name SI See also Portal Volcanism of Canada Volcanism of Eastern Canada References reflist coord missing Ontario Large igneous provinces Category Volcanism of Ontario Category Large igneous provinces Category Dike swarms Category Hotspot volcanism Category Paleoproterozoic volcanism Category Lake Superior Ontario geo stub Canada geology stub ... more details
geology The Flin Flon Snow Lake greenstone belt is one of the largest Paleoproterozoic volcanogenic ... of Manitoba Category Volcanism of Saskatchewan Category Greenstone belts Category Paleoproterozoic ... more details
Dhala crater is an impact crater in the Shivpuri district in the Madhya Pradesh state of India . ref cite web last Dhingra first Deepak title Planetary impacts in focus publisher Current Science date 2008 11 25 url http www.ias.ac.in currsci nov252008 1394.pdf format PDF accessdate 2009 08 19 ref Its age is estimated between 1.7 and 2.1 billion years. Its diameter is estimated at 11 km. It is exposed at the surface. ref cite Earth Impact DB name Dhala accessdate 2009 08 19 ref Dhala Impact Structure is the third oldest impact structure in the Earth. It is highly eroded remnant of paleoproterozoic structure on granitiods. References reflist coord 25 18 N 78 8 E display title Impact cratering on Earth Category Impact craters of India Category Geography of Madhya Pradesh Category Proterozoic impact craters MadhyaPradesh geo stub ... more details
The Siderian pron en sa d ri n , lang el sideros , meaning iron is the first geologic geologic period period in the Paleoproterozoic era geology Era and lasted from 2500 annum Mya to 2300 Mya million years ago . Instead of being based on stratigraphy , these dates are defined chronometrically. Abundance of banded iron formation s BIFs peaked early this period. BIFs were formed as anaerobic algae produced waste oxygen that combined with iron , forming magnetite Fe sub 3 sub O sub 4 sub , an iron oxide . This process cleared iron from the oceans, presumably turning greenish seas clear. Eventually, without an oxygen sink in the oceans, the process created the oxygen rich Earth s atmosphere atmosphere of today. This event is known as the oxygen catastrophe , which according to some geologists triggered the Huronian glaciation ref Paleoclimates The First Two Billion Years James F. Kasting & Shuehi Ono, 2006 http www.jstor.org stable 20209693 ref . The Huronian glaciation took place in the Siderian between 2400 Mya and 2300 Mya ref The Paleoproterozoic Snowball Earth A climate disaster triggered by the evolution of oxygenic photosynthesis Kopp et. al http www.pnas.org content 102 32 11131.full.pdf html ref . References cite web title Siderian Period work GeoWhen Database url http www.stratigraphy.org geowhen stages Siderian.html accessdate January 5, 2006 Notes references references Proterozoic eon Geological history c Category Geologic time scale Category Proterozoic geochronology stub br Siderieg ca Sideri de Siderium es Per odo Sid rico eu Sideriar fr Sid rien ko it Sideriano nl Siderium ja nn Siderium pl Sider pt Sideriano ru sh Siderij vi K Sideros zh ... more details
Geobox Volcanic arc name Great Bear Magmatic Zone other name image image size 280 image caption country Canada region type Regions region Northwest Territories length imperial length round length orientation highest highest elevation highest lat d highest lat m highest lat s highest lat NS N highest long d highest long m highest long s highest long EW W geology geology1 period Proterozoic map map size map caption The Great Bear Magmatic Zone is a linear belt of Proterozoic magma tic rocks in the northwestern Canadian Shield of the Northwest Territories . It is convert 100 km mi 0 abbr on wide and convert 800 km mi 0 abbr on long, extending from Great Slave Lake in the south to Great Bear Lake in the northwest. It was formed about 1,810 million years ago as a result of continental arc volcanism when the Archean Slave craton started to collide with the Paleoproterozoic Hottah terrane to the west. ref http ginkgo.cisti.nrc.ca RPAS rpv?hm HInit&journal cjes&volume 38&afpf e00 094.pdf&calyLang eng Magmatic evolution of the southern Great Bear continental arc, northwestern Canadian Shield geochronological constraints ref Volcanics of the Great Bear Magmatic Zone range from basalt to rhyolite and geologic studies show the Great Bear Magmatic Zone is similar to modern continental volcanic arc s. ref http geology.geoscienceworld.org cgi content abstract 12 2 73 Continental intra arc depressions A nonextensional model for their origin, with a Proterozoic example from Wopmay orogen ref See also Portal Volcanism of Canada Taltson Magmatic Zone Volcanism of Canada Volcanism of Northern Canada References reflist coord missing Northwest Territories Category Volcanism of the Northwest Territories Category Volcanic arcs Category Paleoproterozoic volcanism NorthwestTerritories geo stub Canada geology stub ... more details
Unreferenced stub auto yes date December 2009 Lunar geo time The Eratosthenian period in the lunar geologic timescale runs from 3,200 million years ago to 1,100 million years ago. It is named after the Eratosthenes crater crater Eratosthenes , whose formation marks the beginning of this period. The formation of the Copernicus lunar crater crater Copernicus marks its end, and the beginning of the subsequent Copernician Period. The massive basaltic volcanism of the Imbrian period tapered off and ceased during this long span of lunar time. The youngest lunar lava flows identified from orbital images are tentatively placed near the end of this period. Its Earth equivalent consists of most of the Neoarchean era Archean eon , Paleoproterozoic and Mesoproterozoic eras Proterozoic eon . Timeline Lunar Geological Timescale Category Lunar geologic periods Moon stub br Eratostenian ca Eratosteni da Eratosthenian es Per odo Eratosteniano fr ratosth nien it Eratosteniano nl Eratosthenium ru sv Eratosthenian vi K Eratosthenes ... more details
Unreferenced stub auto yes date December 2009 The Central Lapland Greenstone Belt CLGB is a greenstone belt located in the northern part of the Fennoscandian Shield . The region belongs to Lapland Finland Lapland , northern Finland . The CLGB is part of a much larger belt of Paleoproterozoic greenstones, a cover of metamorphism metamorphosed volcanic and sedimentary rocks that cover the Archean basement, the latter which is representative of the Archaean Karelian craton . Deposition of the cover sequence occurred between about 2.5 annum Ga and 1.8 Ga, thus it preserves information about History of Earth Earth s history from a period that encompass about 700 Ma. Thus, the CLGB records a prolonged and episodic history of rifting , sedimentation and magmatism before the collision and rift closure at about 1.9 Ga. The collision was related to the amalgamation of the supercontinent Columbia supercontinent Columbia . See also List of greenstone belts Coord missing Finland Category Volcanoes of Finland Category Greenstone belts Category Archean volcanism Category Proterozoic volcanism Category Geology of Finland Category Geologic formations Greenstone belts Regional geology stub ... more details
Refimprove date February 2009 The Neoarchean pron en ni .o . r ki . n , also spelled Neoarchaean is a geology geologic era geology era within the Archaean . It spans the period of time from Ma 2800 2500 &mdash the period being defined chronometrically and not referenced to a specific level in a rock section on Earth . Oxygenic photosynthesis first evolved in this era and was accountable for the oxygen catastrophe which was to happen later in the paleoproterozoic from a poisonous buildup of oxygen in the atmosphere, produced by these oxygen producing photoautotrophs, which evolved earlier in the Neoarchean. The supercontinent Kenorland formed during this period, about 2.7 billion years ago. Archean Footer Geological history c Category Geologic time scale Category Archaean 4 geochronology stub br Neoarkean ca Neoarque de Neoarchaikum et Neoarhaikum es Era Neoarcaica fr N oarch en id Neoarkean it Neoarcheano lt Neoarch jus hu Neoarchaikum ms Neoarkean nl Neoarche cum nn Neoarkeikum pl Neoarchaik pt Neoarqueano ru sk Neoarchaikum sh Neoarhej fi Neoarkeeinen maailmankausi sv Neoarkeikum vi i T n Th i C zh ... more details
GOE may mean Galactic Orgonomy Exchange Government Olympic Executive Goldthorpe railway station , England National Rail station code GOE Special Operations Group Argentina Grupo de Operaciones Especiales Argentina , a Special forces special operations force of the Argentine Air Force Grupo de Operaciones Especiales El Salvador Grupo de Operaciones Especiales El Salvador Grupo de Opera es Especiais Portugal Grupo de Opera es Especiais Portugal , a special operations unit of the Public Security Police Force of Macau Grupo de Opera es Especiais Macau Grupo de Opera es Especiais Macau , a special operations unit of the Grupo de Operaciones Especiales Spain Grupo de Operaciones Especiales Spain , a special operations unit of the Spanish Army GOE Brazil Grupo de Opera es Especiais Brazil Grade of Execution in the ISU Judging System figure skating Great Oxygenation Event , a massive environmental change at the beginning of the Paleoproterozoic era. Gaussian Orthogonal Ensemble , an ensemble used in Random matrix theory. Good Ol Edwin , an acronym invented by T man for people with first name Edwin. disambig es GOE fr GOE it GOE ... more details
The Kangaamiut dike swarm old spelling Kang miut is a 2.04 billion year old dike swarm located in the Kangerlussuaq region of western Greenland . ref http www.geus.dk publications bull nr11 nr11 p061 086.pdf Mayborn, K.R. & Lesher, C.E. 2006 Origin and evolution of the Kang miut mafic dyke swarm, West Greenland. In Garde, A.A. & Kalsbeek, F. eds Precambrian crustal evolution and Cretaceous Palaeogene faulting in West Greenland. Geological Survey of Denmark and Greenland Bulletin 11 , 61 86. ref The dikes cut Archean Gneiss orthogneisses and are exposed along approximately convert 150 km mi 0 abbr on of the coast and a similar distance up to the inland ice to the east, covering an area of about convert 18000 km2 mi2 abbr on . To the north it is bounded by the paleoproterozoic Ikertooq shear zone old spelling Ikert q while to the south the boundary is gradational with a gradual reduction in the density of dikes. References Reflist Greenland geo stub regional geology stub coord missing Greenland Category Dike swarms Category Geology of Greenland Category Kangerlussuaq ... more details
Amelia Creek crater is an impact structure or astrobleme , the eroded remnant of a former impact crater , located in the Davenport Murchison National Park Davenport Range , Northern Territory , Australia . ref Cite Earth Impact DB name Amelia Creek linkname AmeliaCreek suffix html accessdate 2008 12 30 ref It lies within a low range of Paleoproterozoic Sedimentary rock sedimentary and Volcanic rock volcanic rocks, which are extensively Fold geology folded and Geologic fault faulted , thus making an eroded impact crater difficult to recognize. It was only discovered by the identification of shatter cone s near its centre ref name mm2003 cite journal author Macdonald FA, Mitchell K title Amelia Creek, Northern Territory, Australia a 20 x 12 km oblique impact structure with no central uplift journal Impact Cratering Bridging the Gap Between Modeling and Observations, February 2003, Houston, Texas, Lunar and Planetary Institute Contribution 1155 volume issue year 2003 pages 47 id http www.lpi.usra.edu meetings impact2003 pdf 8006.pdf Conference abstract br ref . The central shatter cone locality is surrounded by a 20 x 12 km area of anomalous deformation, the asymmetry being possibly related to very oblique impact, but may be at least partly due to the pre existing structural complexity of the rocks ref name mms2005 cite journal author Macdonald FA, Mitchell K, Stewart AJ title Amelia Creek a Proterozoic impact structure in the Davenport Ranges, Northern Territory journal Australian Journal of Earth Sciences volume 52 issue 4 5 year 2005 pages 631 640 id doi 10.1080 08120090500170401 http journalsonline.tandf.co.uk link.asp?id p4mt8066058648u8 Abstract br ref . This deformed zone gives the best estimate for the original size of the crater. Impact took place after folding of the Paleoproterozoic rocks but before deposition of Neoproterozoic and Cambrian rocks which overlie them, thus constraining the impact event to the interval between about 1660 and 600 Annum Ma r ... more details
The Rhyacian pron en ra e si n , lang el rhyax , meaning stream of lava is the second geologic geologic period period in the Paleoproterozoic era geology Era and lasted from 2300 annum Mya to 2050 Mya million years ago . ref name geowhen cite web title Rhyacian Period work GeoWhen Database url http www.stratigraphy.org geowhen stages Rhyacian.html format dead link date August 2010 accessdate January 5, 2006 archiveurl http web.archive.org web 20060819001043 http www.stratigraphy.org geowhen stages Rhyacian.html Bot retrieved archive archivedate August 19, 2006 ref Instead of being based on stratigraphy , these dates are defined chronometrically. ref name ogg cite journal author James G. Ogg title Status on Divisions of the International Geologic Time Scale journal Lethaia year 2004 volume 37 issue pages 183&ndash 199 url http onlinelibrary.wiley.com doi 10.1080 00241160410006492 abstract doi 10.1080 00241160410006492 format &ndash sup http scholar.google.co.uk scholar?hl en&lr &q intitle 3AStatus on Divisions of the International Geologic Time Scale&as publication Lethaia&as ylo 2004&as yhi 2004&btnG Search Scholar search sup ref The Bushveld Bushveld Complex and other similar intrusion s formed during this period. ref name ogg The Huronian glaciation Huronian Makganyene global glaciation began at the start of the Rhyacian and lasted until 2200 Mya ref cite journal doi 10.1073 pnas.0504878102 author Kopp et al. last2 Kirschvink first2 JL last3 Hilburn first3 IA last4 Nash first4 CZ title The Paleoproterozoic Snowball A climate disaster triggered by the evolution of oxygenic photosynthesis journal PNAS volume 102 issue 32 pages 11131 6 year 2005 month August url http www.pnas.org content 102 32 11131.full.pdf html pmid 16061801 pmc 1183582 ref The first known eukaryotes began to evolve in the Rhyacian period. The multicellular Francevillian Group Fossil s, at 2.1 Gyr old are from the Rhyacian period. ref name albani cite journal author1 El Albani, Abderrazak au ... more details
Image Cratons West Gondwana.svg thumb right Approximate location of Mesoproterozoic older than 1.3 Ga cratons in South America and Africa. The S o Lu s and the Luis Alves cratonic fragments Brazil are shown, but the Arequipa Antofalla craton and some minor African cratons are not. Other versions describe the Guiana Shield separated from the Amazonian shield by a depression, and the Sahara craton as a part of this West African craton . The S o Francisco craton is located in the eastern part of South America. Outcrops in the Brazilian states of Minas Gerais and Bahia . It includes a number of different blocks of the Archean basement, separated by orogenic belts. The belts are characterized by sediment basins and passive continental margin, crossed by granite intrusions. The Paleoproterozoic about 2.5 to 2.0 Ga was the source of orogenetic belts and the current configuration of the craton. The S o Francisco craton around 1.0 Ga ago was located in the South of the supercontinent Rodinia and after the fragmentation of Rodinia in the late Proterozoic 700 Ma became a member of the supercontinent Gondwana until its fragmentation in the Jurassic about 180 Ma the opening of the Atlantic Ocean left South Africa in the Congo craton and the S o Francisco in South America. The ancient Paleoproterozoic orogenic belts of the S o Francisco craton rich rocks contain many minerals, particularly iron and gold, and are a major source of income for the mining industry in Brazil. References Cite journal doi 10.1130 0091 7613 2001 029 0319 AWGITN 2.0.CO 2 journal Geology month April year 2001 volume 29 issue 4 pages 319 322 title Assembling West Gondwana in the Neoproterozoic Clues from the S o Francisco craton region, Brazil author Fernando F. Alkmim Stephen Marshak Marco A. Fonseca Cite book title West Gondwana Pre Cenozoic Correlations Across the South Atlantic Region editors R.J. Pankhurst, R.A.J. Trouw, B.B. de Brito Neves, M.J. de Wit series Geological Societ ... more details
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