Late Mesoproterozoic rifting in Arctic Canada during Rodinia assembly: impactogens, trans‐continental far‐field stress and zinc mineralisation

Abstract

This paper challenges the conventional interpretation of a major, economically important Mesoproterozoic intracratonic rift system as a group of aulacogens, proposing instead that they are rifts that developed in response to far-field stress caused by continent-continent collision (impactogens) during supercontinent assembly. The tectonostratigraphic evolution of the Bylot basins (Arctic Canada) records dramatic alternations between extensional and compressional stress regimes, precluding an aulacogen interpretation and favouring an impactogen interpretation. New geochronological data (U-Th-Pb whole-rock depositional age; detrital zircon signatures) provide a record of impactogens that developed in Laurentia's interior as a result of Grenvillian (~1.1 Ga) far-field stress during assembly of the supercontinent Rodinia. Formation of the world-class Nanisivik zinc deposit in one of the rifts is temporally associated with the Grenvillian orogeny, and consequently represents both (i) a rare exception to the global pattern of few ore deposits forming during supercontinent episodes, and (ii) a hitherto unrecognised tectonic setting for carbonate-hosted zinc deposits.

Re-Os geochronology highlights widespread latest Mesoproterozoic (ca. 1090–1050 Ma) cratonic basin development on northern Laurentia

“…based on Re-Os dates of 1048 ± 12 Ma on the Arctic Bay Formation and 1046 ± 16 Ma on the Victor Bay Formation (Gibson et al, 2018). Turner et al (2016) further showed that Grenville-aged zircons were captured only in the upper Bylot Supergroup (Strathcona Sound Formation) and proposed that extension in the Bylot basins was associated with far-field stress from the Amazonia-Laurentia collision.…”

“…The necessity for a long-duration unconformity has also been noted for the Borden Basin given the assumed Mackenzie age for the Nauyat Formation and the ca. 1050 Ma depositional age for the Arctic Bay Formation (Turner et al, 2016;Gibson et al, 2018). Gibson et al (2019) proposed that this unconformity be placed near the contact between the Adams Sound and Arctic Bay Formations.…”

Offshore bedrock geology of Eclipse Sound and Pond Inlet: connecting the structure and stratigraphy of Bylot and northern Baffin islands

“…Bylot Supergroup strata were unconformably deposited above these crystalline basement rocks after 1.267 Ga and until at least 1.1 Ga in Borden basin, one of the Bylot Basins, a regional system of extensional basins (Jackson and Iannelli 1981;Turner et al 2016;Turner 2020; Fig. 1 inset).…”

“…(1) an aulacogen that formed in response to the opening of the proto-Arctic ocean (Poseidon Ocean, Fahrig et al 1981;Jackson and Iannelli 1981) and 2an impactogen (rift system) associated with the assembly of Rodinia (Turner et al 2016). Local patterns of sedimentation and sediment preservation were influenced by a suite of southeast-trending extension-related faults (e.g., Central Borden, Nina Bang, and White Bay fault zones; Fig.…”

“…Harrison et al (2011) also recognised a Cenozoic spreading sequence, late spreading and inversion sequences, and a postspreading succession, all of which are overlain by glacial and younger marine strata. Unconformities also exist within these four successions (e.g., Proterozoic: Sherman et al 2002;Turner 2011;Turner et al 2016;Paleozoic: Trettin 1975;Mesozoic: Miall et al 1980;Haggart et al 2017).…”