The Davis Strait proto-microcontinent: The role of plate tectonic reorganization in continental cleaving

• Published in: Gondwana Research
• Main Authors: Luke Longley, Jordan Phethean, Schiffer, C.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Elsevier 2024
• Subjects: Plate kinematic modelling; Gravity lineaments; Microcontinent; Davis Strait; Transpression; Baffin Bay; Baffin; Greenland; Labrador Sea
• Online Access: https://doi.org/10.1016/j.gr.2024.05.001; https://repository.derby.ac.uk/download/8d125e2cfeec44bce024e3f83fe473a6166cb8023864ac92b0f07da72076d1fb/11016474/1-s2.0-S1342937X24001023-main.pdf

A prolonged period of rifting and seafloor spreading between Greenland and North America formed the Labrador Sea and Baffin Bay oceanic basins, connected by the Davis Strait. However, disagreement exists regarding the exact plate motions between Greenland and Canada, as well as the tectonic evolution of the Davis Strait, with previous models unable to explain the origin of anomalously thick continental crust within the seaway. Here, we present a new plate tectonic reconstruction of Greenland’s separation from Canada, constrained by a new comprehensive set of mid-ocean ridge (MOR) and transform fault lineaments identified using free-air, vertical gradient, and filtered directional gradient maps from the Sandwell and Smith gravity data. Furthermore, the reinterpretation of seismic reflection data offshore West Greenland, along with a newly compiled crustal thickness model, identifies an isolated terrane of relatively thick (19–24 km) continental crust that was separated from Greenland during a newly recognised phase of E-W extension along West Greenland’s margin. We interpret this continental block as an incompletely rifted microcontinent, which we term the Davis Strait proto-microcontinent. Our reconstruction suggests release of the proto-microcontinent coincided with a change in the spreading orientation from ∼ 58 to 49 Myr during the alignment of Canada and Greenland's rifted margins, indicating a fundamental control of lithospheric structure on plate motions. Proto-microcontinent separation was induced by transpression along a newly recognised NE-SW trending transform margin that joined the Labrador Sea and Baffin Bay, prior to development of the Ungava Fracture Zone (UFZ). The location of this transform margin is constrained using our crustal thickness model, which demonstrates a sharp NE-SW trending continent-ocean transition across the northern Saglek basin. We term this newly identified first-order tectonic feature the Pre-Ungava Transform Margin (Pre-UTM), which accommodated early NE-SW motion between ...