Lake level fluctuations in carbonate sequences from the Upper Freeport limestone, Appalachian Basin (Upper Allegheny group, Middle Pennsylvanian)

Conference · Mon Mar 01 04:00:00 EST 1993 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5505479

Valero Garces, B L ^[1]; Gierlowski-Kordesch, E ^[2]

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1. Univ. of Minnesota, Minneapolis, MN (United States). Limnological Research Center
2. Ohio Univ., Athens, OH (United States). Geological Sciences

Lacustrine limestone, several meters in thickness, which occur in cyclothems under coals within the upper half of the Pennsylvanian system in the Appalachian Basin, provide a remarkable case study for exploring lake dynamics within siliciclastic, deltaic-alluvial plain settings. Sedimentologic and petrologic analyses of the lacustrine Upper Freeport Limestone from core material from an area near Indiana, Pennsylvania identify carbonate sequences reflecting a complex history of water level fluctuations within a single lake during the middle Pennsylvanian. Transgression events marked by intraformational conglomerates. Shallowing-upwards sequences are composed of black shales [r arrow] wackestones/packstones [r arrow] laminated limestones [r arrow] banded limestones [r arrow] massive limestones [r arrow] nodular and brecciated limestones. Deepening sequences are composed of nodular and brecciated limestones [r arrow] black shales. Brecciated, nodular layers with pedogenetic features indicate extended periods of subaerial exposure. Using cathodoluminesce, diagenetic studies of the microfacies textures in the shallowing-upwards sequences outline the pattern of water level changes through time in the floodplain carbonate lake. These changes may be related to climatic changes and/or the dynamics of the fluvial-lacustrine system.

• OSTI ID: 5505479
• Report Number(s): CONF-9303211--
• Conference Information: Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 25:2
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
CARBONATE ROCKS
CARBONIFEROUS PERIOD
DEPOSITION
DEVELOPED COUNTRIES
GEOLOGIC AGES
GEOLOGIC FORMATIONS
GEOLOGIC HISTORY
GEOLOGY
LAKES
LIMESTONE
NORTH AMERICA
PALEOZOIC ERA
PENNSYLVANIA
PETROLOGY
ROCKS
SEDIMENTARY ROCKS
STRATIGRAPHY
SURFACE WATERS
USA