Stable isotopic and fluid inclusion evidence for meteoric fluid penetration into an active mountain belt; Alpine Schist, New Zealand

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Authors:Jenkin, G. R. T.; Craw, D.; Fallick, A. E.
Author Affiliations:Primary:
Scottish Universities Research and Reactor Centre, Glasgow, Scotland, United Kingdom
Other:
University of Otago, New Zealand
Volume Title:Journal of Metamorphic Geology
Source:Journal of Metamorphic Geology, 12(4), p.429-444. Publisher: Blackwell, Oxford, United Kingdom. ISSN: 0263-4929
Publication Date:1994
Note:In English. 69 refs.; illus. incl. 3 tables, sketch maps
Summary:Calcite and quartz veins have formed, and are forming, in steeply dipping fissures in this rising metamorphic belt. The fluids which deposited these minerals were mostly under hydrostatic P almost down to the brittle-ductile transition, which has been raised to 5-6 km depth by rapid uplift. Some fluids were trapped under lithostatic P. Fluids in the fissure veins were immiscible H2O + NaCl-CO2 mixtures at 200-350°C. Bulk fluid composition is 15-20 mol. % CO2 and << 4.3 total mol. (CH4 + N2 + Ar/100) mol. H2O. Water H isotopic ratio ΔDH2O in the fissure veins spans -29 to -680/00, Δ^>18OH2O -0.7 to 8.50/00, and bulk C isotopic ratio Δ^>13C ranges from -3.7 to -11.70/00. The O and H isotopic data suggest that the water has a predominantly meteoric source, and has undergone an O isotope shift as a result of interaction with the host metamorphic rock. Similar fluids were present during cooling and uplift. Dissolved C is not wholly derived from residual metamorphic fluids; part may be generated by oxidation of graphite. [R.E.S.]
Subjects:Alpine Schist; C-13/C-12; Calcite; Carbon; Carbonates; Chemical composition; D/H; Deuterium; Fluid inclusions; Fluid phase; Hydrogen; Hydrostatic pressure; Hydrothermal conditions; Inclusions; Isotope ratios; Isotopes; Metamorphic belts; Metamorphic rocks; Metamorphism; Meteoric water; Migration; O-18/O-16; Oxygen; Pressure; Quartz veins; Stable isotopes; Uplifts; Veins; Alpine Fault; Australasia; New Zealand; South Island; Southern Alps
Coordinates:S440000 S423000 E1710000 E1690000
Abstract Numbers:95M/1888
Record ID:1994038836
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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