Zircon U/pb Geochronology of the Precambrian Basement, Pearya Terrane, Northernmost Ellesmere Island

The Pearya terrane is unique as the only documented exotic terrane in the Canadian Arctic Islands. The terrane juxtaposes Meso- to Neoproterozoic age basement against the Archean to Paleoproterozoic age crystalline basement of the Canadian Shield and Greenland. 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 oldest rock units consist of granitoid gneiss with minor occurrences of amphibolite, schist and marble that outcrop in three main belts. Previous U/Pb zircon ages for these crystalline basement occurrences yield ages ranging from the late Mesoproterozoic to the earliest Neoproterozoic. We present new zircon U/Pb SHRIMP data from all three main exposures of crystalline basement exposed in the Pearya terrane. Analysis reveals ages younger than those of most previous work, ranging from 972.2±6.1 Ma to 958.1±7.4 Ma. These new ages contrast with a previous upper intercept age of 1037+25/-20 Ma based on a multi-grain analysis from granitoid gneiss from the Deutchers Glacier basement exposure, and agree with a later concordant multi-grain study from the Philips Inlet granodiorite yielding an age of 965±2 Ma. The expanded age control on the basement units lead to refined correlations between the Pearya terrane and other Meso/Neoproterozoic age provinces. These new ages overlap with data from the Nordaustlandet terrane that range from 967±17 Ma to 939±7 Ma and ages of c. 960 Ma from the Northwestern terrane of Svalbard. Inherited grains observed in the Pearya terrane samples range from 1099-1130 Ma, 1167-1190 Ma, 1499-1519 Ma, 1577-1632 Ma and 1725-1799 Ma, which also are broadly consistent with inherited zircon ages observed in the Nordaustlandet terrane of Svalbard and suggest that the basement incorporates older crustal material. These data provide additional support for the connection drawn between the Pearya terrane and constituent Svalbard terranes, and may aid in constraining the origin of the Pearya terrane in relation to larger scale tectonic events.