ISOTOPIC AND CHEMICAL EVOLUTION OF MINERALIZATION IN SEPTARIAN CONCRETIONS: EVIDENCE FOR EPISODIC PALEOHYDROGEOLOGIC METHANOGENESIS.

D. I. Siegel, Steven C. Chamberlain, William P. Dossert

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Abstract

Detailed chemical and isotopic studies of mineralization of septarian fractures in concretions in the Devonian Marcellus Shale document a complicated paragenesis involving multiple episodes of metal-carbonate precipitation during methane fermentation. It is proposed (1) that a first period of methane fermentation occurred during burial and diagenesis in the Devonian, (2) that a second period occurred as strontium-bearing Silurian brines were displaced upward near the toe of Pleistocene glaciation, and (3) that witherite replaced barite during sulfate reduction and another period of methane fermentation in a Pleistocene mixture of reducing conditions below thick ice cover. Fluid-inclusion data, oxygen-isotope values of carbonate minerals, and strontium-isotope ratios are all consistent with these suggestions.

Original languageEnglish (US)
Pages (from-to)385-394
Number of pages10
JournalGeological Society of America Bulletin
Volume99
Issue number3
StatePublished - Sep 1987

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ASJC Scopus subject areas

  • Earth and Planetary Sciences (miscellaneous)

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