--> Abstract: Late Jurassic – Earliest Cretaceous Stratigraphy, Depositional History and Petroleum Potential, Canadian Arctic Archipelago, by Ashton Embry; #90177 (2013)

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Late Jurassic – Earliest Cretaceous Stratigraphy, Depositional History and Petroleum Potential, Canadian Arctic Archipelago

Ashton Embry

The Late Jurassic to earliest Cretaceous strata of Sverdrup Basin and Banks Basin are up to one kilometre thick and consist of the Ringnes Formation (shale/siltstone- dominant), Awingak Formation (sandstone-dominant) and Deer Bay Formation (shale/siltstone-dominant). The strata comprise a single, second order sequence and are bound by the base Oxfordian, second-order sequence boundary below and the base Hauterivian, first order sequence boundary above. The Oxfordian-Valanginian sequence contains two, third order sequence boundaries of base Tithonian and base Valanginian age and these subdivide the sequence into three, third order sequences. The margins of the Sverdrup Basin were uplifted in latest Middle Jurassic resulting in the formation of a widespread unconformity. Transgression occurred in earliest Oxfordian with a basal transgressive sandstone developed in some areas. A wave dominated delta prograded into the basin from the southeast during the Oxfordian and Kimmeridgian. The basinward edge of the sand-rich delta front deposits is well defined and stretches southwestwards from northern Axel Heiberg Island to northwest Melville Island. Six, 4th order sequences have been delineated in these strata and may be of eustatic origin. Rifting parallel to the Amerasia Basin began in early Oxfordian on Banks Island forming Banks Basin. Marginal uplift occurred in latest Kimmeridgian and a transgression in earliest Tithonian initiated the next sequence. Over most of Sverdrup and Banks basins the Tithonian to Berriasian 3rd order sequence consists of offshore marine shale and siltstone. Nearshore to shoreline sand deposits occur along the southern margin of Sverdrup Basin and do not extend very far into the basin. Five 4th order sequences are recognized in these sand-rich deposits. Uplift in Berriasian terminated the sequence and isolated, very coarse grained sandstone deposits derived from rift shoulders occur along the northern margin of Sverdrup Basin. A transgression occurred in earliest Valanginian and basin subsidence notably increased. This was followed by a major regression which culminated in nonmarine deposition in the central portion of Sverdrup Basin. The sequence was terminated by widespead uplift over all of Sverdrup and Banks basins. This 1st order sequence boundary coincides with the initiation of sea floor spreading in the Amerasia Basin. The climate of the Oxfordian to Valanginian included very cool intervals as evidenced by the occasional presence of large drop stones and glendonites. Major gas and oil fields have been discovered in Kimmeridgian sandstones which are excellent reservoirs. Significant potential exists for future discoveries especially in areas near the shale-out of the sandstones where combination structural-stratigraphic traps can be envisioned. Isolated, late Berriasian sandstones along the northern margin also have potential and are analogous to the oil-bearing Alpine sandstone of Alaska.

AAPG Search and Discovery Article #90177©3P Arctic, Polar Petroleum Potential Conference & Exhibition, Stavanger, Norway, October 15-18, 2013