Zircon U/Pb Geochronology and Whole-rock Geochemistry of the Pearya Terrane, Northernmost Ellesmere Island
Shawn Malone and William McClelland
Geoscience, University of Iowa, Iowa City, IA
The Pearya terrane is unique as the only documented exotic terrane in the Canadian Arctic Islands. The terrane juxtaposes Meso- to Neoproterozoic age meta-igenous basement against the Paleozoic shelf sequence of the Franklinian basin. The tectonic history of the Pearya terrane is complex, marked by episodic magmatism and deformation from the late Mesoproterozoc to Tertiary; however, the early history of the terrane is enigmatic. The crystalline basement units are primarily granitoid orthogneiss with minor occurrences of amphibolite, schist and marble that outcrop in three main belts. New zircon U/Pb SHRIMP data from all three main exposures of crystalline basement reveals ages ranging from 972.2±6.1 Ma to 958.1±7.4 Ma, younger than previously determined late Mesoproterozoic ages. The refined age control on the Pearya terrane’s meta-igneous basement reinforces correlations between other Meso- to Neoproterozoic age provinces in the Arctic Caledonides and the Pearya terrane. The new ages overlap with tectanothermal activity recorded in Svalbard’s Northeastern terrane, ranging from 967±17 Ma to 939±7 Ma, ages of c. 960 Ma from the Northwestern terrane of Svalbard, and ages of 981.4±6.9 Ma to 973.2±4.2 Ma from the lower Kalak nappes in Arctic Norway. Additional constraints on the origin of the Pearya terrane basement orthogneiss and its source are provided by whole-rock trace element and isotope geochemistry.
AAPG Search and Discovery Article #90130©2011 3P Arctic, The Polar Petroleum Potential Conference & Exhibition, Halifax, Nova Scotia, Canada, 30 August-2 September, 2011.�����������������