--> Abstract: Intrabasinal Structural Controls on the Hydraulics of Early Cretaceous Rivers and on the Connectivity and Geometry of Their Channel Deposits, Central Cordilleran Foreland Basin, Wyoming, by M. J. Zalena, L. J. Suttner, J. Nathan Way, and L. C. Furer; #90937 (1998).

Datapages, Inc.Print this page

Abstract: Intrabasinal Structural Controls on the Hydraulics of Early Cretaceous Rivers and on the Connectivity and Geometry of Their Channel Deposits, Central Cordilleran Foreland Basin, Wyoming

ZALEHA, MICHAEL J., LEE J. SUTTNER, J. NATHAN WAY, and LLOYD C. FURER, Indiana University, Bloomington, IN 47405-1403

Summary

Quantitative reconstructions of paleochannel hydraulics, geometries, and architecture show that Early Cretaceous rivers and their deposits were affected by intrabasinal, syndepositional faulting. River-channel depths, widths, and bankfull discharges were highly variable throughout the medial and distal foreland basin. However, the highest discharges (600-800 m3s-1) were in the distal part of the basin, indicative of a regional tributary fluvial system. Paleochannel slopes do not systematically decrease from the medial to distal part of the basin because local slopes were affected by intrabasinal, syndepositional faulting. In an example of cross-stream faulting, channel-belt deposits on the upstream/upthrown fault block are isolated, fine-grained, and have low paleochannel slopes (0.62 x 10-4 to 0.95 x 10-4). Those on the downstream/downthrown block are laterally and vertically connected, medium-grained, with high slopes (1.35 x 10-4 to 1.41 x 10-4). A relative decrease in slope upstream likely increased the cross-stream/along-stream slope ratio increasing the probability of avulsion near the fault. This can account for the differences in the alluvial architecture. In two examples of along-stream faulting, channel-belt deposits on the upthrown block are isolated or laterally connected. Those on the downthrown block are laterally and vertically connected. Avulsion and alluvial architecture were apparently controlled by relative rates of subsidence versus deposition. Field data and results are consistent with existing alluvial architecture models. Attempts to model the tectonics, subsidence, and sediment accumulation in the Central Cordilleran Foreland Basin during the Early Cretaceous need to consider the effects of intrabasinal, syndepositional faulting on sedimentation.

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