Evidence for cold water circulation at DSDP site 395: Isotopes and chemistry of alteration products
A variety of low temperature alteration products occurs in the 573-m-thick section of basaltic rock from Site 395. Carbonate veins, smectities (predominantly saponite), zeolites, goethite, opal, and gypsum, listed in order of decreasing abundance, are present. Values of delta/sup 18/O (SMOW) of calcite veins range from +31.8 to +34.8/sup 0//00, and delta/sup 13/C (PDB) ranges from +2.3 to +4.4/sup 0//00. Apparently the calcite veins were formed at 0--15 /sup 0/C in equilibrium with deep ocean water. Some veins may have formed during glacial periods, when delta/sup 18/O of the deep water was higher than it is presently. The deepest calcite veins were formed in the temperature range 8--15 /sup 0/C. Saponite veins associated with an intrusive dolerite sill (delta/sup 18/O = +9.8 to +24.3%/sub 0/, SMOW) are estimated to have formed in the temperature range 30--160 /sup 0/C. Very extensive circulation (i.e., large water/rock ratios) predominated during alteration of the basalts as evidenced by seawater carbon and sulfur istope ratios in calcite and gypsum and carbon, sulfur and magnesium mass balance considerations.
- Research Organization:
- Lamont-Doherty Geological Observatory of Columbia University, Palisades, New York 10964
- OSTI ID:
- 6287522
- Journal Information:
- J. Geophys. Res.; (United States), Vol. 86:B6
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
MID-ATLANTIC RIDGE
ROCK-FLUID INTERACTIONS
WATER INFLUX
CALCITE
CARBON 13
CHEMICAL COMPOSITION
GYPSUM
ISOTOPE RATIO
OXYGEN 18
SEAWATER
SMECTITE
ALKALINE EARTH METAL COMPOUNDS
ALUMINIUM COMPOUNDS
ALUMINIUM SILICATES
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CALCIUM SULFATES
CARBON COMPOUNDS
CARBON ISOTOPES
CARBONATES
CLAYS
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
HYDROGEN COMPOUNDS
ISOTOPES
LIGHT NUCLEI
MINERALS
NUCLEI
OXYGEN COMPOUNDS
OXYGEN ISOTOPES
SILICATES
SILICON COMPOUNDS
STABLE ISOTOPES
SULFATES
SULFUR COMPOUNDS
WATER
580500* - Oceanography- (1980-1989)