Because the recognition of sea-floor distributing anomalies just dates the postrift development of ocean crust. Usually the very first clear marine magnetic anomalies are situated instead far seaward from the margin, due either to the existence of instead poor anomalies of uncertain beginning closer to the margin (southern Newfoundland and Labrador margins) or even having less magnetic reversals (Scotian and north Newfoundland margins) through the Jurassic and Cretaceous Normal Polarities (
210-160 Ma and 118-83 Ma, correspondingly). More particular times for rifting would result from exposures on land and/or drilling of syn-rift sedimentary sequences. Other quotes may be produced by extrapolating the prices of sea-floor spreading into the margin or by dating of sedimentary sequences or stones on land.
Such times declare that rifting for the older margins might have taken place over a period that is extended the synthesis of ocean crust and might have impacted adjacent margin portions. Initial rifting began as soon as the belated Triassic to Early Jurassic, as evidenced with a wide-spread volcanic pulse understood because the CAMP occasion at 200 Ma (Marzoli, 1999) additionally the existence of rift successions experienced in marginal basins ( e.g. Hiscott et al., 1990; Olsen, 1997). Rifting proceeded in the Jurassic that is late to Cretaceous, as evidenced by basaltic volcanism in basement drill cores of this Newfoundland and Labrador margins ( ag e.g. Continue reading