The Porcupine Fault System of northern Yukon and Alaska is an important tectonic boundary that separates far-traveled fragment of continental crust (North Slope subterrane) from northwestern North America. Tectonic models suggested its major role in the mid-Paleozoic transfer of terranes across the Arctic, as well as strike-slip displacement during the Mesozoic opening of the Arctic Ocean. In this project, we investigated differences in stratigraphy and provenance across this boundary, as well as the timing of brittle deformation. We defined a new sequence of Tonian (ca. 720-1000 Ma) rocks exposed within this area, proposed that they originated several hundreds of kilometers away from their current location, and mapped a complex array of faults related to sinistral and dextral displacement. The Ar-Ar thermochronology and U-Pb dating of vein calcite suggest activity of the fault system in the early Cretaceous during the formation of the Canada Basin (part of the Arctic Ocean), supporting oblique spreading within the basin and coupled displacement of the Arctic Alaska during this time.

The Neoproterozoic to early Paleozoic evolution of North America is characterized by a protracted history of rifting and passive margin development, during the break-up of the supercontinent Rodinia. Along the northern margin, the beginning of continental break-up is often associated with the emplacement of Franklin Large Igneous Province around 720 Ma and the separation of ancestral North America and Siberia. However, passive margin sedimentation started in the late Neoproterozoic to early Paleozoic, more than 150 million years later. In this project, we investigated the Yelverton Formation, a suite of mixed volcanics, carbonates and siliciclastic, exposed on northern Ellesmere Island. The carbonates have an isotopic composition characteristic of Ediacaran deposits. The trace element and isotope geochemistry of volcanic rocks suggested the generation of magma during decompression melting from two mantle sources during the formation of an oceanic basin. We suggested that these data reflect rifting along this margin in Ediacaran and early Cambrian that resulted in the formation of microcontinents along the edge of North America.

The Svalbard archipelago consists of three basement provinces bounded by N-S-trending strike-slip faults that were juxtaposed during the middle Paleozoic. However, the exact timing and relation of strike-slip displacement to the Caledonian orogeny that resulted from the collision between Laurentia and Baltica remains unclear. In this project, we investigated the sinistral Vimsodden-Kosibapasset Shear Zone in southwest Svalbard. We integrated 40Ar/39Ar  muscovite geochronology with microstructural and mineral chemistry data to determine the timing of movement along the shear zone. We determined that displacement occurred ca. 420 Ma, in late Silurian–Early Devonian, and was contemporaneous with the main phase of continental collision in Greenland and Scandinavia. The displacement overlaps with the onset of syn-orogenic sedimentation in fault-controlled basins in northern Svalbard, which likely formed a pull-apart system at the time.