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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 63 (1979)

Issue: 9. (September)

First Page: 1576

Last Page: 1576

Title: Suggested Origin for Gas in Eastern Devonian Shales: ABSTRACT

Author(s): Irving A. Berger

Article Type: Meeting abstract


Kerogen of the Chattanooga Shale in eastern Tennessee and adjacent areas is known to be of predominantly terrestrial origin. The Chattanooga Shale may be viewed as a high-ash, low-rank coal. Recent detailed studies of peat from The Everglades of Florida have led to the observation that the rate at which cellulose is degraded is reduced as the mineral content increases. Knowing of the contribution of terrestrial plant material to the sediments that later became the Chattanooga Shale (which is 75 to 85% mineral matter), we believe that those sediments probably contained an accumulation of cellulose. Slow, anaerobic degradation of that cellulose by methanogenic bacteria would be expected to result in the formation of methane that would then dissolve in other organic componen s of the sediment. Only in those regions where the contribution of aquatically derived organic detritus to the sediment was significant would appreciable amounts of ethane, propane, and higher gaseous hydrocarbons be expected, perhaps as products of low-temperature thermal processes.

These considerations suggest that study of the composition of kerogen in the Chattanooga Shale and its correlatives could delineate those regions of the eastern Devonian shales most likely to be the best sources of methane.

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Copyright 1997 American Association of Petroleum Geologists