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Topic: Paleoarchean

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In the News (Wed 24 Jul 19)

  Selected Abstracts
There are five main geocronological units in the Precambrian history of the Ukrainian Shield: the Paleoarchean, the Mesoarchean, the Neoarchean, and the Paleoproterozoic (the last unit is subdivided into two sub-units: the Paleoproterozoic-I, and the Paleoproterozoic-II).
The Paleoarchean (3.65-3.2 Ga) is represented by rocks of the Western-Azov, the Auly, the Dniester-Bug groups (series) of metamorphic rocks; the Novopavlivka and Gayvorone granitoid complexes.
The low age limit of the Paleoarchean was determined on the magmatic formations of ultramafic-mafic-thonalite rock association of the Novopavlivka complex, and the high one — on enderbites of the Gayvorone and Novopavlivka complexes.
www.geofuel.lviv.net /MISCEL/MPSab/sab019.htm   (689 words)

 v23d in sm04
Estimates for the rate of crustal growth and recycling during Paleoarchean time are tied to the analysis of these ancient crustal remnants.
Sm-Nd and U-Pb isotope data indicate that a fragment of Meso- to Paleoarchean crust occurs in the Churchill craton, on the north shore of Lake Athabasca, Saskatchewan (Canada).
This shear zone may represent the surface expression of a suture between the Meso- to Paleoarchean and younger (Neoarchean?) crust.
www.agu.org /cgi-bin/SFgate/SFgate?&listenv=table&multiple=1&range=1&directget=1&application=sm04&database=/data/epubs/wais/indexes/sm04/sm04&maxhits=200&="V23D"   (2841 words)

Interest in Paleoarchean to early Mesoarchean crust in North America has been sparked by the recent identification of ca.
Thus, these rocks were formed in the late Paleoarchean and show a history of igneous activity and metamorphism in the Mesoarchean and Neoarchean.
Because ancient crustal rocks occur on both the northern and southern margins of the ca.
gsa.confex.com /gsa/2004AM/finalprogram/abstract_75677.htm   (501 words)

 MRNF- Press Release
The Porpoise Cove supracrustal sequence is a unique example of early Paleoarchean crust in the Superior Province.
The discovery of Paleoarchean rocks (> 3.8 Ga) in the Porpoise Cove belt will undoubtedly provide new information on early processes leading to the formation of continental and oceanic crust, as well as on the origin of life on Earth.
The Porpoise Cove sequence is considered as the second window to open on our planet's first billion years of evolution.
www.mrn.gouv.qc.ca /english/press/press-release-detail.jsp?id=1613   (305 words)

 Manitoba Geology | Geological Survey | Mineral Resources Division | Manitoba Industry, Economic Development and Mines
The Assean Lake Domain consists of a southern segment of Meso- to Paleoarchean rocks and a northern segment of Paleoproterozoic gneisses and plutonic rocks that were variably contaminated by Archean rocks.
The Assean Lake ancient crust comprises a collage of Archean crustal segments, trending approximately 090–110°, that are overprinted by Neoarchean and Paleoproterozoic metamorphism and deformation, the latter forming structures trending 060°.
The Assean Lake crustal complex is subdivided into a southern Meso- to Paleoarchean segment and a northern Paleoproterozoic segment.
www.gov.mb.ca /itm/mrd/geo/exp-sup/mbgeology.html   (4728 words)

 Research in West Greenland, Paleoarchean Isua Greenstone Belt
Research in West Greenland, Paleoarchean Isua Greenstone Belt
In 1999 I joined an international team led by the Geological Survey of Denmark and Greenland, investigating the Paleoarchean (3.8 Ga) Isua Greenstone Belt in southern West Greenland.
Sunset across the Greenland Ice Cap, from the Isukasia base camp at about midnight.
www.denison.edu /geology/greene/greenland.html   (661 words)

 RedOrbit - Science - IN BRIEF (Page: 13, Date: 08/18/2006)   (Site not responding. Last check: 2007-09-11)
In a bid to better protect the geological heritage of Yuntai Mountain, dozens of geological experts were invited to form an academic research team to probe into the mountain's physiognomy and the reason for its formation.
They declared the ancient terrane at the Red Stone Valley of the mountain is the first Paleoarchean rock to be found in the centre of the North China Plate.
Leaders of 12 government departments of Fengkai County, Zhaoqing, of South China's Guangdong Province, were organized to visit the county's famous scenic spots in a bid to explore the development of local tourism.
redorbit.com /news/science/621662/in_brief_page_13_date_08182006/?...   (346 words)

 Abstract 51173: DISTRIBUTION OF ARCHEAN STROMATOLITES IN TIME AND SPACE   (Site not responding. Last check: 2007-09-11)
Abstract: Stromatolites are morphologically circumscribed accretionary growth structures with a primary lamination that is, or may be biologically influenced (biogenic).
The earliest records date back to nearly 3.5 Ga, and their worldwide distribution and abundance increase as time progresses: Paleoarchean occurrences (3) are outnumbered by those in the Mesoarchean (7) and Neoarchean (13), while the remaining occurrences are questionably Archean, or questionably stromatolites.
Stromatolites are generally found in Archean sedimentary carbonate rocks, almost always associated with extensive volcanic sequences.
rock.geosociety.org /absindex/annual/1998/51173.htm   (393 words)

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