Correlation of the Ordovician Deicke and Millbrig K-bentonites between the Mississippi Valleyand the southern Appalachians
- Univ. of Cincinnati, OH (USA)
Two widespread Rocklandian age (Middle Ordovician) K-bentonite beds, the Deicke and Millbrig, can be correlated from southern Minnesota and northwestern Iowa through eastern Missouri across Kentucky and central Tennessee to the valley and Ridge of the southern Appalachian Mountains. They are equivalent to beds previously called T-3 or Pencil Cave and T-4 or Mud Cave metabentonites, and thus constitute Ordovician chronostratigraphic marker horizons throughout much of the eastern Mid-Continent. Previous correlations of these beds in the Mississippi Valley by chemical fingerprinting is extended toward the southern Appalachian basin by tracing in surface exposures and on wireline logs. Both beds thicken toward the southeast indicating a volcanic source area that was probably east of South Carolina. The interval between the K-bentonite beds also thickens toward the southeast owing to increased rates of carbonate deposition between the two volcanic episodes. The areal extent of known correlatives of the Deicke and Millbrig is minimally estimated to be 600,000 km{sup 2} and at least 1,122 km{sup 3} of pre-compaction Deicke K-bentonite accumulated as ash in eastern North America. The volume of both beds suggests they rank among the largest air-fall ash deposits documented in the stratigraphic record. 7 figs.
- OSTI ID:
- 5848019
- Journal Information:
- AAPG Bulletin (American Association of Petroleum Geologists); (USA), Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (USA) Vol. 74:11; ISSN AABUD; ISSN 0149-1423
- Country of Publication:
- United States
- Language:
- English
Similar Records
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Related Subjects
580000* -- Geosciences
APPALACHIAN BASIN
BENTONITE
CARBONATE ROCKS
CLAYS
CORRELATIONS
DEPOSITION
ELEMENTS
FEDERAL REGION IV
FEDERAL REGION V
FEDERAL REGION VII
GEOLOGIC AGES
GEOLOGIC STRUCTURES
GEOLOGY
IOWA
KENTUCKY
MINNESOTA
MISSOURI
NONMETALS
NORTH AMERICA
ORDOVICIAN PERIOD
OXYGEN
PALEOZOIC ERA
ROCKS
SEDIMENTARY BASINS
SEDIMENTARY ROCKS
SOUTH CAROLINA
STRATIGRAPHY
TENNESSEE
USA