Saturday, July 26, 2014

The Evolution of the Orosirian Paleoproterozoic Arctic Canada

Sedimentological and geochemical basin analysis of the Paleoproterozoic Penrhyn and Piling groups of Arctic Canada

Partin et al


Paleoproterozoic metasedimentary successions on the western Churchill Province record a history of regional tectonic events spanning the breakup and amalgamation of supercontinents. Metasedimentary successions in the northeastern part of the Trans-Hudson orogeny, including the Penrhyn and Piling groups of Melville Peninsula and Baffin Island, respectively, have been understudied with respect to their basin evolution records. We present new sedimentological, geochemical, and geochronological data for the Penrhyn and Piling groups that record deposition on the Rae craton. New detrital zircon U-Pb age data indicates that deposition of the Penrhyn Group started after ∼1897 Ma and post-dates deposition of most of the Piling Group. The new maximum age constraints and stratigraphy of the Penrhyn Group do not support previous lithostratigraphic correlation with the Piling Group. Deposition of the lower Piling Group occurred in an epicontinental basin setting. The occurrence of detritus from the Meta Incognita microcontinent in the upper Piling Group (Bravo Lake and Longstaff Bluff formations) is interpreted to signal the onset of foreland basin deposition. The details of sedimentation in the Piling foreland basin provide an additional constraint to discerning the polarity of subduction between the Rae craton and Meta Incognita microcontinent that closed the Piling basin. We conclude that the Piling foreland system shows characteristics of a pro-foreland basin, implying that the Rae craton was the lower plate in the collision with the Meta Incognita microcontinent. Finally, with new stratigraphic and detrital zircon geochronological data for the Penrhyn and Piling groups, we provide a comparison with other sedimentary successions on the Rae craton whose histories were influenced by similar regional tectonic events.

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