Abstract

Apatite fission-track and (U–Th–Sm)/He data for samples with Proterozoic–Neogene lithologic ages from eastern Ellesmere, Devon, and Baffin islands in the Canadian Arctic Archipelago and northwest Greenland provide insights into the complex thermal history of this region. Most data reflect exhumational cooling of the region as a sediment source area for the developing Sverdrup Basin to the west during late Paleozoic – Mesozoic time. Samples proximal to the basin margin record late Paleozoic cooling consistent with erosion of uplifted rift flanks and widespread clastic sedimentation during early rifting and thermal subsidence. Data from distal samples are consistent with early Mesozoic epeirogenic denudational cooling during periods of high sediment supply from well-developed river systems. Around northern Baffin Bay, the data record erosional cooling of uplifted rift flanks in response to Late Cretaceous rifting. Rapid denudation rates are indicated for southeastern Devon Island, compatible with thick Upper Cretaceous strata offshore in Lancaster Sound. Slower denudation rates are indicated for northwest Greenland. Along Nares Strait, data reflect mafic volcanism or erosional exhumation associated with strike-slip and (or) thrust displacements during the Paleogene Eurekan orogeny and offer limited support for the existence of a Wegener fault. Fission-track ages older than those obtained in central Ellesmere Island, however, suggest that active tectonics occurred earlier near the strait, and strike-slip tectonism and deformation were likely partitioned across a relatively wide belt. Apatites obtained from Archean gneisses and Franklinian dykes have up to 500 ppm Sm, and up to 15% of the radiogenic He is Sm derived.

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