|2007 GSA Denver Annual Meeting (28–31 October 2007)|
|Paper No. 34-2|
|Presentation Time: 1:50 PM-2:10 PM|
GLOBAL RECORD OF LARGE IGNEOUS PROVINCES [LIPS] AND ITS USE IN PALEOCONTINENTAL RECONSTRUCTIONS
ERNST, Richard E., Ernst Geosciences (and Dept. Earth Sci., Carleton Univ., Ottawa), 43 Margrave Ave, Ottawa, ON K1T 3Y2, Canada, Richard.Ernst@ErnstGeosciences.com and BLEEKER, Wouter, Geological Survey Canada, 601 Booth St, Ottawa, ON K1A 0E8, Canada|
Large Igneous Provinces (LIPs) are short-lived (or pulsed) intraplate-style magmatic events with large area/volume, comprising mainly mafic (-ultramafic) flood basalts, their plumbing system (dykes, sills & layered intrusions), associated silicic magmatism, and, in the Archean, tholeiite-komatiite greenstone belts. LIPs are ideal tools for reconstructing Proterozoic supercontinents: Rodinia, Nuna (Columbia), and Kenorland (or Superia, Sclavia and Vaalbara supercratons). The record of LIPs & interpreted LIP fragments for a crustal block can be efficiently summarized as a barcode [1,2]. Comparison of such barcodes from now distant fragments of continental crust is key to identifying which crustal fragments may have been nearest neighbours, and if so, over what time intervals . Furthermore, use of associated dyke swarms to reconstruct giant radiating or linear swarm geometry provides a criterion for orienting the nearest neighbours . Herein we present the first "Global LIP Barcode Chart" with information for all major crustal blocks over the period 0-2.6 Ga. Well-populated barcodes include those of Laurentia & Baltica (in the Mesoproterozoic) and Superior & Karelia (in the Paleoproterozoic). However, there are also many blocks (e.g. Amazonia, Bastar, Samartia, Tanzania, Volga-Uralia, West Africa & Zimbabwe) with few if any well-dated events. A major geochronological campaign coordinated globally, could quickly complete these barcode records, providing numerous tight robust constraints on pre-Pangea reconstructions [3,4]. The barcode approach is illustrated with our proposed 2.6-2.1 Ga Superia reconstruction of North China, greater Karelia (Karelia+Kola), Hearne & Wyoming (from east to west) along the southern margin of the Superior craton [5,2]. We also compare 1.8-1.2 Ga barcodes and discuss possible Nuna (Columbia) reconstructions. The distribution of 0.9-0.7 Ga LIPs is key to understanding the paleogeography of Rodinia and its breakup history [6,7]. REFS.:  Bleeker 2003, Lithos 71: 99.  Bleeker & Ernst 2006, in: Hanski et al. (eds.) Taylor & Francis, London.  Bleeker 2004, Geosci. Canada 31: 179.  Ernst & Buchan, 2004, Geosci. Canada 31: 103.  Ernst & Bleeker, 2007, [extended abstract] www.Nuna2007.ca.  Ernst et al., 2007 Prec. Res. in press.  Li et al., 2007, Prec. Res. in press.
2007 GSA Denver Annual Meeting (28–31 October 2007)
General Information for this Meeting
|Session No. 34|
Pulse of the Earth: Geochronology and Paleomagnetism of Large Igneous Provinces—The Key to Reconstructing Precambrian Supercontinents
Colorado Convention Center: 605/607
1:30 PM-5:30 PM, Sunday, 28 October 2007
Geological Society of America Abstracts with Programs, Vol. 39, No. 6, p. 97
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