Abstract
Destruction of the Ordovician passive margin of eastern North America is recorded by an upward deepening succession of carbonates, shales, and flysch. A compilation of the age of shelf drowning (carbonate‐to‐shale transition) reveals the degree to which orogeny was diachronous both across and along strike. Shelf drowning occurred first at the northern end of the orogen in Newfoundland, then at the southern end of the orogen in Georgia, and finally in Quebec. Diachronism is attributed to oblique collision between an irregular passive margin, that had a deep embayment in Quebec, and at least one east dipping subduction complex. The rate of plate convergence during collision is estimated at 1 to 2 cm/yr, and the minimum width of the ocean that closed is estimated at 500 to 900 km. Far‐traveled deepwater sequences in the thrust belt contain anomalously old Taconic flysch, related to early arrival of the continental slope/rise at a west advancing trench then located far to the east. The drowning isochron map provides a new basis for estimating tectonic transport distances of four of these allochthons (about 165 to 450 km), results not readily obtained by conventional structural analysis.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
