Compositional Trends within a Clastic Wedge Adjacent to a Fold-Thrust Belt: Indianola Group, Central Utah, U.S.A.
- P. A. Allen and
- P. Homewood
Published Online: 5 MAY 2009
Copyright © 1986 The International Association of Sedimentologists
How to Cite
Lawton, T. F. (1986) Compositional Trends within a Clastic Wedge Adjacent to a Fold-Thrust Belt: Indianola Group, Central Utah, U.S.A., in Foreland Basins (eds P. A. Allen and P. Homewood), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444303810.ch22
- Published Online: 5 MAY 2009
- Published Print: 22 DEC 1986
Print ISBN: 9780632017324
Online ISBN: 9781444303810
- compositional trends within clastic wedge adjacent to fold-thrust belt - Indianola Group, central Utah, U.S.A;
- Cretaceous Indianola Group - synorogenic clastic wedge within central Utah;
- Indianola Group stratigraphy;
- petrography of Indianola group;
- conglomerate clast data, Chicken Creek, Gunnison Plateau;
- detrital mineralogy of Indianola Group;
- interaction of basin-margin tectonics and basin fill
The Indianola Group, a coarse-grained clastic wedge at the western margin of the Cretaceous Cordilleran foreland basin in central Utah, was derived from the unroofing of the Sevier orogenic belt lying to the west. Compositional trends in Indianola Group conglomerates and sandstones confirm that the clastic detritus was eroded from an uplifted miogeoclinal and cratonal section of Precambrian to Jurassic age. The miogeoclinal prism consists of Precambrian to Cambrian quartzite and argillite units and middle to late Palaeozoic carbonate strata, while the Mesozoic cratonal section is dominated by sandstone. Thrusting and uplift of the section resulted in deposition of carbonate-rich detritus eroded from the Palaeozoic section in the lower part of the Indianola Group and quartzose detritus from the Precambrian and Cambrian section in the upper part. The upsection enrichment in quartz is reflected in both conglomerate-clast populations and detrital modes of sandstones. Chert grains are an important derivative of the carbonate provenance and provide durable evidence of a carbonate source even in rocks lacking detrital carbonate grains.
The combination of compositional trends and Indianola depositional patterns suggest that influxes of contrasting detritus may be tied to major ramp uplift on two thrust systems. Deposition of the initial carbonate-rich wedge occurred during ramping and uplift of the Canyon Range thrust in late Albian time. Deposition of alluvial-fan deposits in the overlying quartzose wedge resulted from uplift during ramping of the Pavant thrust. Almost all of the Indianola detritus, however, was derived from the Canyon Range plate, first during uplift above the active Canyon Range thrust and second as the plate rose passively above the younger Pavant system in late Santonian to Campanian time. Frontal structures developed during late Campanian thrusting folded the Indianola Group and terminated subsidence along the basin margin.