Oxygen and hydrogen isotope study of minerals from metapelitic rocks, staurolite to sillimanite zones, Mica Creek, British Columbia
Oxygen and hydrogen isotope analyses have been made of coexisting quartz, ilmenite, muscovite, and biotite from Late Precambrian metapelitic rocks, staurolite-kyanite to K-feldspar-muscovite-sillimanite zones, from Mica Creek, British Columbia. The delta/sup 18/O and delta D values of these minerals are generally uniform and do not decrease significantly with increasing metamorphic grade. This implies that there has not been significant infiltration of deep crustal fluids that has been suggested for some other high-grade metamorphic terranes. The uniformity of oxygen isotope compositions of the Mica Creek rocks may reflect isotopic uniformity in the sedimentary protolith rather than widespread exchange with an isotopically homogeneous metamorphic pore fluid. Temperature estimates based upon /sup 18/O exchange thermometry for samples below the sillimanite zone are in reasonable agreement with the results of garnet-biotite Fe-Mg exchange thermometry. In the higher grade rocks, the oxygen isotope and garnet-biotite thermometry yield results which disagree by about 100/sup 0/C. The highest temperatures recorded by oxygen isotope thermometry in the higher grade rocks, 595/sup 0/C, are at least 60/sup 0/C below the minimum temperatures required by phase equilibria. These discrepancies appear to result from pervasive equilibrium retrograde exchange of oxygen isotopes between coexisting minerals. Retrograd-oxygen isotope exchange may be a general characteristic of high grade metamorphic rocks and oxygen isotope thermometry may not usually record peak metamorphic temperatures if they significantly exceed 600/sup 0/C.
- Research Organization:
- Univ. of Utah, Salt Lake City (USA)
- OSTI ID:
- 6634017
- Report Number(s):
- CONF-8510489-
- Journal Information:
- Geol. Soc. Am., Abstr. Programs; (United States), Vol. 17; Conference: 98. annual meeting of the Geological Society of America, Orlando, FL, USA, 28 Oct 1985
- Country of Publication:
- United States
- Language:
- English
Similar Records
Stable isotope systematics of medium-grade pelitic rocks of southwestern Maine: Implications of postmetamorphic exchange
Element partitioning and thermal-compositional patterns in coexisting muscovites and biotites, Black Hills, SD
Related Subjects
58 GEOSCIENCES
BRITISH COLUMBIA
METAMORPHIC ROCKS
CHEMICAL COMPOSITION
GEOTHERMOMETRY
PETROCHEMISTRY
PETROGENESIS
BIOTITE
HYDROGEN ISOTOPES
HYDROTHERMAL ALTERATION
ISOTOPE RATIO
MINERALOGY
MUSCOVITE
OXYGEN ISOTOPES
PRECAMBRIAN ERA
QUANTITATIVE CHEMICAL ANALYSIS
QUARTZ
CANADA
CHALCOGENIDES
CHEMICAL ANALYSIS
GEOLOGIC AGES
ISOTOPES
MICA
MINERALS
NORTH AMERICA
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
ROCKS
SILICATE MINERALS
SILICON COMPOUNDS
SILICON OXIDES
152002* - Geothermal Data & Theory- Properties of Minerals & Rocks
580400 - Geochemistry- (-1989)
580300 - Mineralogy
Petrology
& Rock Mechanics- (-1989)