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The AAPG/Datapages Combined Publications Database

Journal of Sedimentary Research (SEPM)

Abstract


Journal of Sedimentary Petrology
Vol. 57 (1987)No. 2. (March), Pages 373-377

Oxygen Isotopes and the Origin of Quartz: PERSPECTIVE

Harvey Blatt

ABSTRACT

Published data indicate that in igneous rocks the ^dgr18O of quartz averages about +9^pmil; in metamorphic rocks, +13 to +14^pmil; in sandstones, +11^pmil; in shales, +19^pmil; quartz overgrowths in sandstones, +20^pmil; and cherts, +28^pmil. Either a very large proportion of the silt and clay-size quartz in shales (about 90% of the total quartz in shales) is secondary, or the isotopic data are incomplete. It is concluded that the latter interpret tion is correct because published isotopic analyses of metamorphic rocks consider only the coarser-grained rocks. Phyllites and slates, whose quartz is nearly all of silt and clay size and has more positive ^dgr18O values than quartz from schists and gneisses, probably supplies the bulk of quartz to mudrocks.


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