Structural Control on Distribution of Sedimentary Facies in the PennsylvanianMinturn Formation of North-Central Colorado (Chapter Y)

摘要

The purpose of the paper is to document paleocurrent trends and faciesdistributions in depositional sequences in the Pennsylvanian Minturn Formation near the villages of McCoy and Bond, Colorado. A secondary purpose is to provide a possible explanation that relates these trends and distributions to fault movements that occurred along the basin margin. The Minturn Formation is a thick (as much as 1,921 m, 6,300 ft) accumulation of clastic and minor carbonate sediments deposited along the eastern margin of the central Colorado basin during Middle Pennsylvanian (Atokan and Desmoinesian) time. The source of the arkosic clastic sediments probably was the Ancestral Front Range, which flanked the basin on its east side. Numerous relative sea-level changes during deposition of the Minturn Formation resulted in a series of transgressive-regressive sedimentary cycles. These cycles average about 30 m (100 ft) in thickness and contain a variety of marine and nonmarine deposits.