Early Paleozoic rifting and reactivation of a passive-margin rift: Insights from detrital zircon provenance signatures of the Potsdam Group, Ottawa graben

Early Paleozoic rifting and reactivation of a passive-margin rift: Insights from detrital zircon provenance signatures of the Potsdam Group, Ottawa graben: Comment

“…Thus, the Ausable Formation sensu Lowe et al (2018) is up to 400 m thicker than San-ford and Arnott's (2010) Covey Hill (Ausa ble) Formation and is a different stratigraphic concept as they assigned the Chippewa Bay and Edwardsville members of Sanford and Arnott (2010) to their Keeseville Formation. Another nomenclatural problem in Lowe et al (2018Lowe et al ( , also 2017) is restriction and upgrading of Sanford and Arnott's (2010) Hannawa Falls Member (to 199 m of red fluvial siliciclastics and upper dune sand) within the Covey Hill (Ausable) Formation to 0-25 m of aeolian sandstone of a "Hannawa Falls Formation" that overlies the Ausable. NACSN (2005) recommendations on "redefinition" mean the Hannawa Falls of Sanford and Arnott (2010) should have a different name when "restricted" to the dune sandstone.…”

“…The age(s) and vertical and lateral continuity of sedimentary rocks are key to determining sediment and detrital zircon provenance and paleogeography of the OBa. Lowe et al (2018Lowe et al ( , also 2017 combine outcrop with drill core data in an area with low relief, much Quaternary cover, and many synand post-depositional faults. As suggested, in part, above, problems in Lowe et al's (2018Lowe et al's ( , also 2017 OBa synthesis include: (1) a stratigraphic nomenclature that redefines, without comment, a number of earlier defined units (e.g., their "Potsdam" and "Hannawa Falls"); (2) extension of the "Potsdam Group" up into the Ordovician; (3) correlations (e.g., their "Rivière aux Outardes Member") that subvert the allostratigraphic synthesis; (4) not relating the succession to eustatic signatures and sequence stratigraphy elsewhere in east Laurentia; (5) biostratigraphic errors in correlation; (6) misrepresentation of stratigraphic contacts and depositional facies (e.g., Altona and Theresa formations).…”

“…Clark's (1966) "Potsdam Group" included upper sandstones and dolostones now brought to the Lower Ordovician Theresa Formation, and Sanford and Arnott (2010) and Lowe et al (2017Lowe et al ( , 2018 expanded the "Group" by including the lithologically dissimilar Altona Formation (Landing et al, 2009) as a basal member, while defining nomenclaturally different "Potsdam" subdivisions. Thus, the Ausable Formation sensu Lowe et al (2018) is up to 400 m thicker than San-ford and Arnott's (2010) Covey Hill (Ausa ble) Formation and is a different stratigraphic concept as they assigned the Chippewa Bay and Edwardsville members of Sanford and Arnott (2010) to their Keeseville Formation. Another nomenclatural problem in Lowe et al (2018Lowe et al ( , also 2017) is restriction and upgrading of Sanford and Arnott's (2010) Hannawa Falls Member (to 199 m of red fluvial siliciclastics and upper dune sand) within the Covey Hill (Ausable) Formation to 0-25 m of aeolian sandstone of a "Hannawa Falls Formation" that overlies the Ausable.…”

Stratigraphy of the Middle to Upper Ordovician foreland-basin succession, Ottawa Embayment: emphasis on the Turinian-Chatfieldian succession

“…The embayment's axis coincides with the axial trace of the intracratonic Ottawa-Bonnechère graben ( Fig. 4.1; Kay, 1942), a long-lived feature beginning as an aborted Neoproterozoic continental rift (Burke and Dewey, 1972;McCausland et al, 2005) followed by Paleozoic and Mesozoic faulting in response to distal orogenesis, Mesozoic heating and uplift, and Quaternary neotectonics (Burke and Dewey, 1973;Crough, 1981;Dix and Molgat, 1998;Rimando and Benn, 2005;Dix and Al Rodhan, 2006;McCausland et al, 2007;Ma and Eaton, 2007;Dix and Al Dulami, 2010;Dix and Jolicoeur, 2011;Roden-Tice et al, 2005Hardie et al, 2017;Lowe et al, 2017Lowe et al, , 2018.…”

“…2.1). It represents a long-lived corridor of structural and thermal events, including: a late Precambrian aborted rift; Early Paleozoic, Mesozoic, and Quaternary faulting; fault reactivation and post-Paleozoic uplift; and sustained seismicity especially along the graben's northern limit (Burke and Dewey, 1973;Crough, 1981;Roden-Tice et al, 2005Rimando and Benn, 2005;Dix and Al Rodhan, 2006;Ma and Eaton, 2007;Dix and Jolicoeur, 2011;McCausland et al, 2007;Nurkhanuly and Dix, 2014;Hardie et al, 2017;Lowe et al, 2018).…”