Summary

The lower Cretaceous Spinney Hill Member represents the transition from estuarine complexes of the underlying Mannville Group to the open marine shales of the Joli Fou Formation. In this setting the Spinney Hill Member is contained in the Transgressive Systems Tract (TST). Only the most general aspects of this non-marine to marine transition were documented in the literature despite relatively good well log control in south-central Saskatchewan. The available core control is limited and most of the core is 1 inch wireline. The non-marine to marine transition is composed of several small scale Transgressive-Regressive (T-R) cycles. Sandstone was deposited during the regressive phase and mudstone during the transgressions. A sequence stratigraphic framework based on the recognition and correlation of bounding discontinuities in the Spinney Hill Member has been proposed and from tiffs framework the details of sand body geometry and stacking patterns were described. The depositional history and the history of relative sea level during the onset of the Joli Fou transgression follow from this framework. Based on the geometry of the sand bodies and their overall stacking patterns the Spinney Hill Member was interpreted as a series of backstepping incised shoreface deposits formed during periods of stillstand in an overall base level rise.

Both the sandstone and the mudstone in the Spinney Hill Member contain associated glauconite. Glaucony beating horizons are commonly associated with transgressions and typically occur at the bases of T-R cyles. Sequence stratigraphic studies have emphasized the possible stratigraphic significance of glaucony, however the distribution of glaucony in the different parts of a depositional sequence have not been well documented. The primary objective of this project is to document the distribution and maturity of the glaucony contained in the different pans of the depositional sequences of the Spinney Hill Member to evaluate the stratigraphic significance of the glauconite.

AAPG Search and Discovery Article #90937©1998 AAPG Annual Convention and Exhibition, Salt Lake City, Utah