Loading...
U-Pb geochronology of detrital, inherited, and igneous zircon from the Triassic Eurydice formation and underlying basement, offshore southeast Nova Scotia, Canada
Germain, Rémi
Germain, Rémi
Citations
Altmetric:
Advisor
Editor
Date
Date Issued
2023
Date Submitted
Keywords
Collections
Research Projects
Organizational Units
Journal Issue
Embargo Expires
2024-11-29
Abstract
The purpose of this study was to determine the provenance of the Late Triassic syn-rift sedimentary
rocks of the Eurydice Formation, part of the Mesozoic–Cenozoic Scotian Basin, and the metasedimentary
and plutonic rocks forming its underlying basement, offshore southeast Nova Scotia. During the
Paleozoic, the accretion of multiple exotic terranes to Laurentia was followed by the collision with
Gondwana and the formation of Pangea. These events led to the formation of the Appalachians. The
Meguma terrane of Nova Scotia, Canada, was the last exotic terrane to collide with composite eastern
Laurentia. It consists of latest Ediacaran–Devonian metasedimentary and metavolcanic rocks and
Devonian–Carboniferous plutonic rocks. The Eurydice Formation is the oldest sedimentary unit in the
Scotian Basin, deposited during the Triassic breakup of Pangea. The nature of the underlying basement
has been previously inferred from petrographic, geochemical, and geophysical evidence, but provenance
study is key to identify the basement.
U-Pb LA-ICPMS zircon geochronology was carried out on 22 rock samples collected from historic
petroleum exploration wells in offshore Nova Scotia and was supported by optical microscopy and
automated mineralogy. Detrital zircon analyses from five late Ediacaran or younger metasedimentary
rocks revealed mid-Paleoproterozoic and/or Cryogenian–Ediacaran populations, consistent with
signatures observed in exposed portions of the Meguma terrane on land. Three granitoid rock samples
yielded Late Devonian to early Carboniferous crystallization ages, consistent with mid-Paleozoic syn- to
post-tectonic peraluminous granitic plutons of the Meguma terrane on land. A granodiorite, with a
previously reported whole-rock eNd(370Ma) value of ~ -13, yielded a ~573 Ma crystallization age, predating
the deposition of the sedimentary and volcanic rocks of the Meguma terrane. This age is consistent with
Pan-African high-K calc-alkaline post-collisional plutonism in Northwest Africa, suggesting a potential
genetic link. Significant mid-Paleoproterozoic, Ediacaran, and Late Devonian detrital zircon populations
in rock samples from the Eurydice Formation suggest local sources from the metasedimentary Meguma
Supergroup and from Late Devonian felsic/intermediate plutonic rocks. Notably, an absence of zircon
from the rift-related volcanics of the Silurian White Rock Formation of northwest Nova Scotia is
observed. These results support the previous interpretation that the Meguma terrane extends to the
southeast in offshore Nova Scotia and has a Northwest African origin. Furthermore, zircon grains of the
rift-related volcanic rocks of the White Rock Formation are absent southeast of Nova Scotia, suggesting
that these rocks are probably not related to the rifting between the Meguma terrane and Gondwana, but
between the Meguma terrane and an outboard terrane.
Associated Publications
Rights
Copyright of the original work is retained by the author.