Biostratigraphy and paleoecology of the Upper Cretaceous calcareous nannofossils in the Western Interior Basin, North America

D. K. Watkins, T. J. Bralower, J. M. Covington, C. G. Fisher

Research output: Contribution to journalArticle

18 Scopus citations

Abstract

Nannofossils are restricted largely to the Greenhorn and Niobrara cycles, with most study to date concentrated on the Greenhorn cycle assemblages. Paleoecologic studies of the Greenhorn indicate initial invasion of oceanic waters into the basin from the south, with rapid lateral and northward expansion. Assemblage diversities are initially low, but attain open ocean values by peak transgression. Two surface watermasses (northern and southern) are evident at initial oceanic invasion, with a third developing by peak transgression. Rhythmic bedding in the Greenhorn near peak transgression appears related to surface water fertility cycles. Studies in the Niobrara indicate the presence of seven standard nannofossil zones. -from Authors

Original languageEnglish (US)
Pages (from-to)521-537
Number of pages17
JournalGeological Association of Canada Special Paper
Volume39
StatePublished - Jan 1 1993

All Science Journal Classification (ASJC) codes

  • Fuel Technology
  • Geology
  • Geochemistry and Petrology

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