Transverse and Longitudinal Gilbert-Type Deltas, Tertiary Coalmont Formation, North Park Basin, Colorado, USA
- Albina Colella2 and
- David B. Prior3
Published Online: 2 APR 2009
Copyright © 1990 The International Association of Sedimentologists
How to Cite
Flores, R. M. (1990) Transverse and Longitudinal Gilbert-Type Deltas, Tertiary Coalmont Formation, North Park Basin, Colorado, USA, in Coarse-Grained Deltas (eds A. Colella and D. B. Prior), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444303858.ch12
Universita della Calabria, Italy
Atlantic Geoscience Center, Nova Scotia, Canada
- Published Online: 2 APR 2009
- Published Print: 19 OCT 1990
Print ISBN: 9780632028948
Online ISBN: 9781444303858
- North Park Basin - transpressional basin with several tectonic;
- North Park Basin, developing during Palaeocene;
- Tertiary Coalmont formation;
- longitudinal Gilbert-type deltaic facies;
- bottomset beds, exhibiting narrow U-shaped burrows;
- V-shaped burrows, showing downward-bent sediment layers
The transpressional, intermontane North Park Basin, Colorado, provides excellent examples of sandrich Gilbert-type deltas that prograded into freshwater lacustrine environments. Gilbert-type deltaic sandstones are present in the coal-bearing Palaeocene and Eocene Coalmont Formation.
Two types of Gilbert-type sandstone facies are recognized based on their site of deposition, sedimentological properties and nature of the facies of contributing fluvial systems. The transverse Gilbert-type deltaic facies is formed along the basin margin and is composed of vertically stacked sandstone with foreset beds that are thin, slightly variable in thickness and steeply dipping. Multilateral, conglomeratic channel sandstones are formed landward of this deltaic sandstone facies. The longitudinal Gilbert-type deltaic facies is developed in the basin centre and consists of overlapped sandstone bodies with foreset beds that are thick, highly variable in thickness, gently dipping, and interbedded with silty interforesets. The longitudinal deltaic sandstone facies passes upslope into syndepositional growth faults and into multistorey, en echelon fluvial channel sandstones.
The transverse, Gilbert-type deltaic sandstone facies was deposited in a rapidly subsiding shallow basin fed by bedload of braided streams. The longitudinal, Gilbert-type deltaic sandstone facies was deposited in a slowly subsiding deep basin, fed by a mixed load or meandering streams. Here, slope-producing, syndepositional growth faults controlled accretion and thickness of the foreset beds.