Biological Markers in Lower Jurassic Synrift Lacustrine Black Shales, Hartford Basin, Connecticut, U.S.A.

Authors

Michael A. Kruge, Montclair State UniversityFollow
John F. Hubert, University of Massachusetts Amherst
Jay F. Akes, Southern Illinois University Carbondale
Paul E. Meriney, University of Massachusetts AmherstFollow

Document Type

Article

Publication Date

1990

Journal / Book Title

Organic Geochemistry

Abstract

The East Berlin Formation (Lower Jurassic, Hartford basin, Connecticut, U.S.A.) is distinctive for its six cyclic units of lacustrine black shale and gray mudstone. separated by playa and fluvial redbeds. The black shales arc each about a meter thick and were deposited in subtropical, thermally stratified, oligomictic lakes, the youngest of which (lakes 3 through 6) were large enough to flood most of the basin and attained depths of several tens of meters.

The saturate fractions of solvent extracts of organic-rich black shales from each of the six lakes, collected at fresh roadcuts near East Berlin, arc dominated by extended homologous series of n-alkanes, alkylcyclohexanes, and branched chain alkanes. A striking feature of the black shales is the presence of a series of extended tricyclic terpanes from C₂₀ to at least C₄₁. Hopanes arc either not detectable or present only in subordinate quantities relative to the tricyclic terpanes. The samples arc depleted in hopanes in part because of the elevated maturity level (mid to late oil window). Tricyclic terpane concentrations may also have been enhanced by fractionation effects related to oil expulsion out of the black shales. In addition, the original organic matter may have been exceptionally rich in tricyclic terpane precursors, i.e. fossil lipids of prokaryotes present in anoxic, moderately saline, alkaline lakes.

DOI

10.1016/0146-6380(90)90006-L

MSU Digital Commons Citation

Kruge, Michael A.; Hubert, John F.; Akes, Jay F.; and Meriney, Paul E., "Biological Markers in Lower Jurassic Synrift Lacustrine Black Shales, Hartford Basin, Connecticut, U.S.A." (1990). Department of Earth and Environmental Studies Faculty Scholarship and Creative Works. 94.
https://digitalcommons.montclair.edu/earth-environ-studies-facpubs/94

Published Citation

Kruge, M.A., Hubert, J.F., Akes, R.J. and Meriney, P. E., 1990, Biological markers in Lower Jurassic synrift lacustrine black shales, Hartford basin, Connecticut, USA. Organic Geochemistry 15:281-289.