--> Abstract: Lower Upper Triassic (Carnian) Stratigraphy and Depositional History, Sverdrup Basin, Canadian Arctic Islands, by A. Embry; #90096 (2009)

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Lower Upper Triassic (Carnian) Stratigraphy and Depositional History, Sverdrup Basin, Canadian Arctic Islands

Ashton Embry
Geological Survey of Canada, Calgary, AB, Canada.

Carnian (Lower Upper Triassic) strata occur throughout the Sverdrup Basin and are up to 1500 m thick. The strata consist mainly of siliclastics and the main sediment source area was Crockerland, a low lying land area which lay to the north of the basin. The Greenland and Canadian cratonic areas, to the east and south respectively, also contributed sediment. On the basin flanks, the Carnian succession is bound above and below by major unconformities and it comprises a second order sequence. The unconformable sequence boundaries can be traced basinward where they consist of prominent, maximum regressive surfaces. Significant depositional and tectonic shifts occurred across both the lower and upper sequence boundaries and both were formed by tectonic uplift followed by collapse and rapid transgression. The relatively brief, tectonic episodes which resulted in the formation of these major, 2nd order sequence boundaries appear to be related to plate tectonic readjustments, given that similar age, tectonically-driven, sequence boundaries occur in basins throughout the world.

The 2nd order Carnian sequence contains two, 3rd order sequence boundaries which can be correlated throughout the basin and allow the delineation of three 3rd order Carnian sequences. The basal 3rd order Carnian sequence (early Carnian) consists of a thin, limestone-dominant transgressive systems tract and an overlying, thick regressive systems tract (RST) (maximum thickness 600 m). The RST consists of a basinward-thickening, progradational, outer shelf to slope shale and siltstone unit gradationally overlain by inner to mid shelf, silty limestone. The middle 3rd order Carnian sequence (Mid-Carnian) consists of a thin, transgressive limestone unit which is overlain by a diverse RST. In the western Sverdrup Basin the RST consists mainly of a southward-prograding succession of outer shelf shale and siltstone overlain by thick, inner to mid shelf sandstone and minor limestone. The facies distribution in the upper 3rd order sequence (Upper Carnian) in the eastern Sverdrup Basin is very similar to the underlying sequence. The Carnian succession contains potential reservoir units and excellent petroleum source rocks. Potential traps are associated with unconformities, facies changes, salt domes and swells, and Eurekan structures.


AAPG Search and Discover Article #90096©2009 AAPG 3-P Arctic Conference and Exhibition, Moscow, Russia