Complex Rhythmic Sedimentation Related to Third-Order Sea-Level Variations: Upper Cretaceous, Western Interior Basin, USA
- P. L. de Boer2,
- D. G. Smith3
Published Online: 29 APR 2009
Copyright © 1994 The International Association of Sedimentologists
Orbital Forcing and Cyclic Sequences
How to Cite
Ricken, W. (2009) Complex Rhythmic Sedimentation Related to Third-Order Sea-Level Variations: Upper Cretaceous, Western Interior Basin, USA, in Orbital Forcing and Cyclic Sequences (eds P. L. de Boer and D. G. Smith), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444304039.ch14
Utrecht, The Netherlands
- Published Online: 29 APR 2009
- Published Print: 28 JAN 1994
Print ISBN: 9780632037360
Online ISBN: 9781444304039
- complex rhythmic sedimentation, relating to third-order sea-level variations - Upper Cretaceous;
- Original flux variations;
- Marl-limestone cycles;
- Niobrara cycle;
- well-established transgressive-regressive history
Rhythmic sedimentation in Upper Cretaceous carbonaceous marls and chalks deposited in the Western Interior Basin is quantified in order to assess the original flux variations governing these rhythms. Investigations are carried out using carbonate mass balance calculations, isotope studies and numerical flux models for three sediment components. Sections are investigated from mid-basin, reflecting various positions on two major third-order transgressive–regressive (TR) cycles (i.e. Greenhorn TR cycle and Niobrara TR cycle). Estimation of the dominant flux pattern and quantification of relative depositional fluxes is performed by evaluating different Corg–CaCO3 dilution and concentration styles.
The shallow seaway of the Western Interior Basin is sensitive to small-scale climatic cycles, due to combined variations in carbonate productivity, clastic supply from continental sources and redox conditions. Rhythmic deposition is expressed differently for different portions of each of the two third-order TR cycles. Section intervals reflecting maximum transgression show combined variations in carbonate productivity and redox rhythms, while the more regressive units show variations in calcareous productivity, clastic dilution and dysaerobic bottom waters. For most of the cycles investigated, persistent dysaerobic bottom waters are largely uninfluenced by variations in pelagic carbonate productivity, except for section intervals representing maximum transgression. This suggests the existence of a circulation pattern in which a mixed surface water zone was underlain by more stratified, oxygen-depleted water masses with slow circulation.
Only the carbonate-rich units, which are formed during sea-level high-stands, have substantial diagenetic overprint; this overprint is medium to low in the more marly units. Differential carbonate dissolution and cementation processes lower the carbonate content in the marl beds and augment the carbonate content in the limestone beds. The organic carbon content is passively enriched in the marl beds and reduced in the limestone beds. These processes, along with differential compaction, augment the original bedding phenomena.