Detrital muscovite geochronology and the Cretaceous tectonics of the inner Scotian Shelf, southeastern Canada

作者：Reynolds Peter H^*; Pe Piper Georgia; Piper David J W

来源：Canadian Journal of Earth Sciences, 2012, 49(12): 1558-1566.

DOI：10.1139/e2012-062

Geochronology of detrital muscovite from the Lower Cretaceous of the central Scotian Basin has shown predominant supply of Meguma terrane detritus, including muscovite with Alleghanian (mid-Carboniferous to Permian) ages from the inner Scotian Shelf. In this study, 87 detrital muscovite grains from five wells in the eastern Scotian Basin, representing depositional ages from Tithonian to Early Albian, were dated by single-grain Ar-40/Ar-39 techniques. Previous work shows that the provenance of this sediment was different from wells in the central Scotian Basin. Compared with the central Scotian Basin, the muscovite age populations from the eastern Scotian Basin have more (20% versus 7%) pre-Devonian ages, derived from inboard terranes of the Appalachians. In both the central and eastern Scotian Basin, most old grains are found in the Tithonian and the Aptian-Albian, with fewer in the Valanginian and almost none in the Kimmeridgian and the Hauterivian-Barremian. These data suggest rapid unroofing of the Meguma terrane in the Kimmeridgian and Hauterivian-Barremian and greater supply of sediment from Newfoundland to the eastern Scotian Basin in the Tithonian and Aptian-Albian. Compared with the central Scotian Basin, which has most ages in the range 340-300 Ma, the muscovite age populations from the eastern Scotian Basin have a higher proportion of 420-340 Ma and in particular 300-260 Ma ages. Such late Alleghanian overprinting of argon ages is very rare on land in Nova Scotia, but in the Maritimes Basin, this was the time of uplift and erosion of strata.

• 出版日期2012-12