Origin of the Carbonate Sediments in the Wilkins Peak Member of the Lacustrine Green River Formation (Eocene), Wyoming, USA

  1. Albert Matter and
  2. Maurice E. Tucker
  1. Joseph P. Smoot

Published Online: 29 JUN 2009

DOI: 10.1002/9781444303698.ch6

Modern and Ancient Lake Sediments

Modern and Ancient Lake Sediments

How to Cite

Smoot, J. P. (1978) Origin of the Carbonate Sediments in the Wilkins Peak Member of the Lacustrine Green River Formation (Eocene), Wyoming, USA, in Modern and Ancient Lake Sediments (eds A. Matter and M. E. Tucker), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444303698.ch6

Author Information

  1. Department of Earth and Planetary Sciences, The Johns Hopkins University, Baltimore, Maryland, USA

  1. Department of Earth and Space Sciences, State University of New York, Stony Brook, New York U.S.A.

Publication History

  1. Published Online: 29 JUN 2009
  2. Published Print: 24 NOV 1978

ISBN Information

Print ISBN: 9780632002344

Online ISBN: 9781444303698

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Keywords:

  • dense dolomite surface crusts formed on the evaporative mudflat;
  • mound-shape travertine tufa precipitated along spring-fed streams;
  • caliche crusts and cements formed in the alluvial fans;
  • a large accumulation of‘primary’ dolomite;
  • Eocene Green River Formation;
  • dolomite surface crusts

Summary

The Eocene Green River Formation is one of the largest non-marine carbonate deposits in the world. The Wilkins Peak Member, which is made up predominantly of ‘primary’ dolomite micrite, has been interpreted as a playa-lake complex. The following subenvironments are recognized: alluvial fans, fringing sandflat with broad, sheet-like basinward tongues, evaporative mudflat and ephemeral lake. The major mode of sedimentation was by sheetwash in a normally subaerially-exposed, evaporative environment. The carbonate sediments are mostly sand to silt-sized dolomite peloidal intraclasts which are found in traction-deposited bed forms. These intraclasts are thought to have formed by the disintegration of three basic kinds of syndepositional precipitates: (1) dense dolomite surface crusts formed on the evaporative mudflat; (2) mound-shape travertine tufa precipitated along spring-fed streams; and (3) caliche crusts and cements formed in the alluvial fans. A chemical mass-balance shows that all of the carbonate sediments in the Wilkins Peak could have been produced by this mechanism in the available time.

The important consequences of this study are: (1) it provides a mechanism of lacustrine carbonate production without a standing lake; (2) it shows that hard, carbonate crusts, which are very abundant in some lake basins, can provide fine-grained sediment; and (3) a large accumulation of ‘primary’ dolomite can take place through the erosion of syndepositional crusts.