Timing of Mississippi Valley-type mineralization: Relation to Appalachian orogenic events

Journal Article · Thu Nov 01 00:00:00 EST 1990 · Geology; (USA)

DOI:https://doi.org/10.1130/0091-7613(1990)018<1115:TOMVTM>2.3.CO;2· OSTI ID:5572876

Kesler, S E; van der Pluijm, B A ^[1]

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1. Univ. of Michigan, Ann Arbor (USA)

Although Mississippi Valley-type deposits in Lower Ordovician carbonate rocks of the Appalachian orogen are commonly interpreted to have been precipitated by basinal brines, the timing of brine migration remains poorly known. Late Paleozoic K-Ar isotopic ages on authigenic K-feldspar, which is widespread in Appalachian carbonate rocks, as well as evidence of paleomagnetic overprints of similar age, have focused attention on the possibility that these Mississippi Valley-type deposits formed as a result of late Paleozoic deformation. Geologic and geochemical similarities among most of these deposits, from Georgia to Newfoundland, including unusually high sphalerite/galena ratios, isotopically heavy sulfur, and relatively nonradiogenic lead, suggest that they are coeval. Sphalerite sand that parallels host-rock layering in many of the deposits indicates that mineralization occurred before regional deformation. Although the late Paleozoic age of deformation in the southern Appalachians provides little constraint on the age of Mississippi Valley-type mineralization, deformation of these deposits in the Newfoundland Appalachians is early to middle Paleozoic in age. Thus, if Ordovician-hosted, Appalachian Mississippi Valley-type deposits are coeval, they must have formed by middle Paleozoic time and cannot be the product of a late Paleozoic fluid-expulsion event. This hypothesis has important implications for basin evolution, fluid events, and remagnetization in the Appalachians.

• OSTI ID: 5572876
• Journal Information: Geology; (USA), Vol. 18:11; ISSN 0091-7613
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
APPALACHIAN MOUNTAINS
OROGENESIS
CARBONATE ROCKS
MINERALIZATION
AGE ESTIMATION
ARGON ISOTOPES
BRINES
DEFORMATION
GEOLOGIC HISTORY
ISOTOPE DATING
ISOTOPE RATIO
ORDOVICIAN PERIOD
PALEOMAGNETISM
PALEOZOIC ERA
POTASSIUM ISOTOPES
PRECIPITATION
SULFUR ISOTOPES
TECTONICS
ALKALI METAL ISOTOPES
GEOLOGIC AGES
ISOTOPES
MAGNETISM
MOUNTAINS
ROCKS
SEDIMENTARY ROCKS
SEPARATION PROCESSES
580000* - Geosciences