U.S. Department of EnergyOffice of Scientific and Technical Information
Development and application of laser microprobe techniques for oxygen isotope analysis of silicates, and, fluid/rock interaction during and after granulite-facies metamorphism, highland southwestern complex, Sri Lanka
Abstract
The extent of fluid/rock interaction within the crust is a function of crustal depth, with large hydrothermal systems common in the brittle, hydrostatically pressured upper crust, but restricted fluid flow in the lithostatically pressured lower crust. To quantify this fluid/rock interaction, a Nd-YAG/CO[sub 2] laser microprobe system was constructed to analyze oxygen isotope ratios in silicates. Developed protocols produce high precision in [sigma][sup 18]O ([+-]0.2, 1[sigma]) and accuracy comparable to conventional extraction techniques on samples of feldspar and quartz as small as 0.3mg. Analysis of sub-millimeter domains in quartz and feldspar in granite from the Isle of Skye, Scotland, reveals complex intragranular zonation. Contrasting heterogeneous and homogeneous [sigma][sup 18]O zonation patterns are revealed in samples <10m apart. These differences suggest fluid flow and isotopic exchange was highly heterogeneous. It has been proposed that granulite-facies metamorphism in the Highland Southwestern Complex (HSWC), Sri Lanka, resulted from the pervasive influx of CO[sub 2], with the marbles and calc-silicates within the HSWC a proposed fluid source. The petrologic and stable isotopic characteristic of HSWC marbles are inconsistent with extensive decarbonation. Wollastonite calc-silicates occur as deformed bands and as post-metamorphis veins with isotopic compositions that suggest vein fluids that are at least in partmore »
- Authors:
- Publication Date:
- Research Org.:
- Wisconsin Univ., Madison, WI (United States)
- OSTI Identifier:
- 5630770
- Resource Type:
- Miscellaneous
- Resource Relation:
- Other Information: Thesis (Ph.D.)
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 15 GEOTHERMAL ENERGY; 58 GEOSCIENCES; HYDROTHERMAL SYSTEMS; ROCK-FLUID INTERACTIONS; SILICATES; ION MICROPROBE ANALYSIS; ISOTOPE RATIO; SRI LANKA; GEOCHEMISTRY; FELDSPARS; FLUID FLOW; GRANULITES; ISOTOPIC EXCHANGE; OXYGEN ISOTOPES; PETROLOGY; QUARTZ; ASIA; CHEMICAL ANALYSIS; CHEMISTRY; DEVELOPING COUNTRIES; ENERGY SYSTEMS; GEOLOGY; GEOTHERMAL SYSTEMS; ISLANDS; ISOTOPES; METAMORPHIC ROCKS; MICROANALYSIS; MINERALS; NONDESTRUCTIVE ANALYSIS; OXIDE MINERALS; OXYGEN COMPOUNDS; ROCKS; SILICATE MINERALS; SILICON COMPOUNDS; 150200* - Geology & Hydrology of Geothermal Systems; 152003 - Geothermal Data & Theory- Rock-Water-Gas Interactions; 580000 - Geosciences
Citation Formats
Elsenheimer, D W. Development and application of laser microprobe techniques for oxygen isotope analysis of silicates, and, fluid/rock interaction during and after granulite-facies metamorphism, highland southwestern complex, Sri Lanka. United States: N. p., 1992.
Web.
Elsenheimer, D W. Development and application of laser microprobe techniques for oxygen isotope analysis of silicates, and, fluid/rock interaction during and after granulite-facies metamorphism, highland southwestern complex, Sri Lanka. United States.
Elsenheimer, D W. 1992.
"Development and application of laser microprobe techniques for oxygen isotope analysis of silicates, and, fluid/rock interaction during and after granulite-facies metamorphism, highland southwestern complex, Sri Lanka". United States.
@article{osti_5630770,
title = {Development and application of laser microprobe techniques for oxygen isotope analysis of silicates, and, fluid/rock interaction during and after granulite-facies metamorphism, highland southwestern complex, Sri Lanka},
author = {Elsenheimer, D W},
abstractNote = {The extent of fluid/rock interaction within the crust is a function of crustal depth, with large hydrothermal systems common in the brittle, hydrostatically pressured upper crust, but restricted fluid flow in the lithostatically pressured lower crust. To quantify this fluid/rock interaction, a Nd-YAG/CO[sub 2] laser microprobe system was constructed to analyze oxygen isotope ratios in silicates. Developed protocols produce high precision in [sigma][sup 18]O ([+-]0.2, 1[sigma]) and accuracy comparable to conventional extraction techniques on samples of feldspar and quartz as small as 0.3mg. Analysis of sub-millimeter domains in quartz and feldspar in granite from the Isle of Skye, Scotland, reveals complex intragranular zonation. Contrasting heterogeneous and homogeneous [sigma][sup 18]O zonation patterns are revealed in samples <10m apart. These differences suggest fluid flow and isotopic exchange was highly heterogeneous. It has been proposed that granulite-facies metamorphism in the Highland Southwestern Complex (HSWC), Sri Lanka, resulted from the pervasive influx of CO[sub 2], with the marbles and calc-silicates within the HSWC a proposed fluid source. The petrologic and stable isotopic characteristic of HSWC marbles are inconsistent with extensive decarbonation. Wollastonite calc-silicates occur as deformed bands and as post-metamorphis veins with isotopic compositions that suggest vein fluids that are at least in part magmatic. Post-metamorphic magmatic activity is responsible for the formation of secondary disseminated graphite growth in the HSWC. This graphite has magmatic isotopic compositions and is associated with vein graphite and amphibolite-granulite facies transitions zones. Similar features in Kerela Khondalite Belt, South India, may suggest a common metamorphic history for the two terranes.},
doi = {},
url = {https://www.osti.gov/biblio/5630770},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Jan 01 00:00:00 EST 1992},
month = {Wed Jan 01 00:00:00 EST 1992}
}