Rj. Ryan et M. Zentilli, ALLOCYCLIC AND THERMOCHRONOLOGICAL CONSTRAINTS ON THE EVOLUTION OF THE MARITIMES BASIN OF EASTERN CANADA, Atlantic geology, 29(3), 1993, pp. 187-197
The tectonic and metallogenetic evolution of the Maritimes Basin is co
nstrained by its thermochronology, structure, and stratigraphy. Allocy
clic sedimentary deposition occurred within the basin and reflects the
shifts in tectonic subsidence from local rapid events to regional slo
wer events. Apatite thermochronology combined with vitrinite reflectan
ce data suggest that an additional 1.5 to 4 km of strata were deposite
d prior to 280 Ma and subsequently eroded. The organic maturation and
the apatite fission track modelling indicate that the exhumation took
place from 280 to 200 Ma. The thermochronology data are consistent wit
h a paleogeothermal gradient of approximately 25-degrees-C/km. The str
ucture of the Maritimes Basin and the paleogeographic reconstructions
based on paleomagnetics and sediment dispersal studies suggest that th
e basin developed as a continental wrench-fault basin. The exhumation
of the basin may be the result of pre-rift bulging or due to the erosi
on of strata deposited above sea level following a waning in the sedim
ent supply into the basin. The timing of basin-brine expulsion events
which have been hypothesized to explain Pb-Zn-Ba deposits in the basin
are constrained to pre 280 Ma, prior to the onset of exhumation. Redb
ed Cu mineralization can be explained as being related to a period of
reddening of the sandstones of the basin during the exhumation of the
strata.