| Title | Lithostratigraphic and allostratigraphic framework of the Cambrian-Ordovician Potsdam Group and correlations across Early Paleozoic southern Laurentia |
| |
| Author | Lowe, D G; Arnott, R W; Nowlan, G S; McCracken, A D |
| Source | Canadian Journal of Earth Sciences vol. 54, 2017 p. 550-585, https://doi.org/10.1139/cjes-2016-0151  Open Access |
| Year | 2017 |
| Alt Series | Earth Sciences Sector, Contribution Series 20160315 |
| Publisher | Canadian Science Publishing |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf |
| Province | Ontario |
| NTS | 31G; 31H |
| Lat/Long WENS | -76.0000 -72.0000 46.0000 45.0000 |
| Subjects | marine geology; sedimentology; structural geology; tectonics; Nature and Environment; grabens; rifts; fluvial deposits; fluvial systems; eolian deposits; marine sediments; erosion; unconformities;
paleogeography; orogenies; Ordovician; Cambrian |
| Illustrations | geological sketch maps; tables; location maps; cross-sections, stratigraphic; photographs; stratigraphic columns; drillhole logs; photomicrographs |
| Program | Science laboratory network |
| Released | 2017 02 06 |
| Abstract | The Potsdam Group is a Cambrian to Lower Ordovician siliciclastic unit that crops out along the southeastern margins of the Ottawa graben. From its base upward, the Potsdam consists of the Ausable,
Hannawa Falls, and Keeseville formations. In addition, the Potsdam is subdivided into three allounits: allounit 1 comprises the Ausable and Hannawa Falls, and allounits 2 and 3, respectively, the lower and upper parts of the Keeseville. Allounit 1
records Early to Middle Cambrian syn-rift arkosic fluvial sedimentation (Ausable Formation) with interfingering mudstone, arkose, and dolostone of the marine Altona Member recording transgression of the easternmost part of the Ottawa graben. Rift
sedimentation was followed by a Middle Cambrian climate change resulting in local quartzose aeolian sedimentation (Hannawa Falls Formation). Allounit 1 sedimentation termination coincided with latest(?) Middle Cambrian tectonic reactivation of parts
of the Ottawa graben. Allounit 2 (lower Keeseville) records mainly Upper Cambrian quartzose fluvial sedimentation, with transgression of the northern Ottawa graben resulting in deposition of mixed carbonate-siliciclastic strata of the marine Rivière
Aux Outardes Member. Sedimentation was then terminated by an earliest Ordovician regression and unconformity development. Allounit 3 (upper Keeseville) records diachronous transgression across the Ottawa graben that by the Arenigian culminated in
mixed carbonate-siliciclastic, shallow marine sedimentation (Theresa Formation). The contact separating the Potsdam Group and Theresa Formation is conformable, except locally in parts of the northern Ottawa graben where the presence of localized
islands and (or) coastal salients resulted in subaerial exposure and erosion of the uppermost Potsdam strata, and accordingly unconformity development. |
| Summary | (Plain Language Summary, not published)
A detailed study of sedimentary rocks that overly Precambrian basement in the Ottawa area improves the understanding of basin evolution in the early
Phanerozoic. Key to this study is the interpretations of the microfossils, which give ages to the sedimentary succession. This study improves the understanding of the early geological evolution of northeastern North America. |
| GEOSCAN ID | 299634 |
|
|