Lead isotopic signatures of New England massive sulfide deposits: paleotectonic and economic implications

Conference · Tue Jan 01 04:00:00 EST 1985 · Geol. Soc. Am., Abstr. Programs; (United States)

OSTI ID:6454483

LeHuray, A P; Slack, J F

Lead isotopic ratios in volcanogenic massive sulfide deposits (VMSD) commonly reflect large-scale crustal structure, apparently because Pb is scavenged from materials of diverse provenance. Pb-isotopes may, therefore, be useful in identifying and correlating tectonic terranes. The New England Appalachians contain at least three broadly defined tectonostratigraphic terranes (Zen, 1983). Pb-isotopes in galenas and other sulfide minerals in VMSD from the three terranes are distinct. Deposits in Avalonia, along the Maine coast (Black Hawk, Harborside) are characterized by relatively narrow ranges of /sup 206/Pb//sup 204/Pb (6/4), /sup 207/Pb//sup 204/Pb (7/4), and /sup 208/Pb//sup 204/Pb (8/4), which are similar to Pb-isotopic ratios for VMSD in the Carolina slate belt. The few VMSD clearly within Craton X have restricted ranges of Pb-isotopes that are distinctive in their high 7/4 and 8/4 values relative to Avalonian deposits, and which are isotopically identical to those of the Bathurst deposits, N.B. VMSD of the North American (NA) craton have variable Pb-isotopic ratios, and are less radiogenic than those of Craton X; some deposits of the NA craton are also less radiogenic than Avalonian deposits. Pb-isotopic ratios in deposits of the Vermont Cu belt range in 7/4 from MORB-like (15.47) to relatively high (15.58), suggesting that mixing with continental material was locally important. The Pb-isotopic groupings for the various New England terranes indicate that isotopically distinct source materials were available in each. The data also indicate that very large VMSD, or those rich in Pb, need not have highly radiogenic Pb-isotopic signatures.

• Research Organization: Lamont-Doherty Geological Observatory, Palisades, NY (USA)
• OSTI ID: 6454483
• Report Number(s): CONF-8510489-
• Conference Information: Journal Name: Geol. Soc. Am., Abstr. Programs; (United States) Journal Volume: 17
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580300* -- Mineralogy
Petrology
& Rock Mechanics-- (-1989)
580400 -- Geochemistry-- (-1989)
CHEMICAL ANALYSIS
CHEMICAL COMPOSITION
CHEMISTRY
COPPER ORES
CORRELATIONS
FEDERAL REGION I
GEOCHEMISTRY
GEOLOGIC HISTORY
GEOLOGY
ISOTOPE RATIO
ISOTOPES
LEAD ISOTOPES
LEAD ORES
MINERALIZATION
MINERALOGY
MINERALS
NORTH AMERICA
ORES
PETROGENESIS
QUANTITATIVE CHEMICAL ANALYSIS
STRATIGRAPHY
SULFIDE MINERALS
TECTONICS
USA