Geochemical affinities of metavolcanic rocks from the Mt. Rogers Formation, SW VA

Conference · Tue Mar 01 04:00:00 EST 1994 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:6819461

Hernandez, D; Gunter, C; Ryan, J G ^[1]

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1. Univ. of South Florida, Tampa, FL (United States). Dept. of Geology

Metavolcanic rocks of the late Proterozoic Mt. Rogers Formation (MRF) are believed to be related to the opening of the Iapetus ocean (Rankin et al. 1989; Geol. North America v. F-2). The authors have conducted bulk chemical and trace element analysis on a selection of greenstones and metarhyolites from the MRF for comparison to more recent volcanic associations, so as to place constraints on the nature of MRF magmatism. The analyzed greenstones include samples from the Lower MRF, a dike intruding MRF rhyolites on Whitetop Mtn., and a greenstone from the lower Unicoi Formation. All save the Unicoi sample are Ne normative, and plot as alkali basalts in the Yoder and Tilley (1970) tetrahedron; and all show consistent enrichment in Ti, Zr and Y, and variable enrichments of the more mobile K, Sr, and Ba. The MRF greenstones bear strong compositional similarities to those of the Catoctin Formation. The MRF greenstones are more trace element enriched than either Eastern North American diabases (ENA), or modern ocean ridge basalts. Among recent basalts the MRF greenstones are most similar to alkaline lavas from St. Helena and Hawaii, and enriched flood basalts like those from the Deccan Traps. Chemical differences between the MRF and ENA associations indicate differences in the character of the rifting event: while the chemically depleted ENA lavas erupted during the reopening of a recently collided margin, the enriched nature of the MRF lavas point either to a plume source, or to the melting of enriched subcontinental mantle during rifting.

• OSTI ID: 6819461
• Report Number(s): CONF-9404221--
• Conference Information: Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 26:4
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
CHEMICAL COMPOSITION
CHEMISTRY
DEVELOPED COUNTRIES
GEOCHEMISTRY
GEOLOGIC FORMATIONS
GEOLOGY
IGNEOUS ROCKS
METAMORPHIC ROCKS
NORTH AMERICA
PETROGENESIS
PETROLOGY
ROCKS
USA
VIRGINIA
VOLCANIC ROCKS