David H. McNeil1
(1) Geological Survey of Canada, Calgary, AB
Abstract: Quantitative benthic foraminiferal data in sequence stratigraphy - Central Saskatchewan Kimberlite project
During the mid-Cretaceous, dozens of kimberlites erupted near present-day central Saskatchewan. Quantitative foraminiferal data from Cretaceous sediments, cored during diamond exploration, have been analyzed in the context of a transgressive-regressive sequence stratigraphic model. Absolute and relative species abundance, generic composition, and foraminiferal morphogroups have been used to document a complete cycle in the upper Albian Viking and Westgate formations.
The Viking contains lagoonal and marginal marine foraminiferal assemblages (initial transgressive systems tract). At the base of the Westgate, marine mudstones overlying transgressive lag deposits (flooding surface), contain shallow-marine, coarse-grained, agglutinated foraminifera. Foram-iniferal diversity and abundance increase upsection until a maximum is reached and deeper water species dominate (maximum marine flooding). Data suggests that maximum flooding is more realistically portrayed as a zone rather than a surface. The upper Westgate contains a lower diversity assemblage of agglutinated foraminifera indicating the regressive systems tract. Oscillations in absolute abundance represent progradational pulses. Application of sequence stratigraphy, coupled with detailed foraminiferal distributions, provides precise correlation (meter-scaled) through central Saskatchewan. Regional and global correlation is also obtainable and is backed up biostratigraphically and radiometrically (Pb/U radiometric dates).
AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana