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Oxygen isotopic evidence for meteoric water interaction with the Captains Bay pluton, Aleutian Islands

1979; Elsevier BV; Volume: 45; Issue: 1 Linguagem: Inglês

10.1016/0012-821x(79)90103-1

1385-013X

M. R. Perfit, J.R. Lawrence,

Geology and Paleoclimatology Research

Low18O/16O values have been found in rocks from the Captains Bay pluton and surrounding country rocks on Unalaska Island in the Aleutian Islands. The pluton is surrounded by a metamorphic aureole in which the country rocks have been domed, faulted and chaotically fractured. Samples with lower18O/16O values (δ18O = −4.1 to +2.7‰, SMOW) commonly have interstitial micrographic intergrowths of quartz and turbid potassium feldspar. These facts suggest extensive interaction of circulating meteoric waters with the pluton. Unalaska Island must have been subaerially exposed at or shortly after the time of intrusion of the pluton. The pervasive low-grade metamorphism of the “early series” volcanic rocks of all of the Aleutian Islands might be a result of the interaction of intrusive bodies with meteoric waters rather than the consequence of ridge subduction.