Evidence for cold water circulation at DSDP Site 395; isotopes and chemistry of alteration products

Online Access: Get full text
doi: 10.1029/JB086iB06p05125
Author(s): Lawrence, J. R.; Drever, J. I.
Author Affiliation(s): Primary:
Lamont-Doherty Geol. Obs., Palisades, NY, United States
Univ. Wyo., Dep. Geol., United States
Volume Title: Journal of Geophysical Research
Source: Journal of Geophysical Research, 86(B6), p.5125-5133. Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0148-0227
Note: In English. Lamont-Doherty Geol. Obs.; Contrib. No. 3096. 21 refs.; illus. incl. 66 anals., 4 tables
Summary: A variety of low temperature alteration products occurs in the 573-m-thick section of basaltic rock from Site 395. Carbonate veins, smectites (pre-dominantly saponite), zeolites, goethite, opal, and gypsum, listed in order of decreasing abundance, are present. Values of δ180 (SMOW) of calcite veins range from +31.8 to +34.8%o, and δ13C (PDB) ranges from +2.3 to +4.4%o. Apparently the calcite veins were formed at 0-15°C in equilibrium with deep ocean water. Some veins may have formed during glacial periods when δ18o of the deep water was higher than it is presently. The deepest calcite veins were formed in the temperature range 8 - 15°C. Saponite veins associated with an intrusive dolerite sill (δ180 = +9.8 to +24.3%o, SMOW) are estimated to have formed in the temperature range 30 - 160°C. Very extensive circulation (i.e., large water/rock ratios) predominated during alteration of the basalts as evidenced by seawater carbon and sulfur isotope ratios in calcite and gypsum and carbon, sulfur and magnesium mass balance considerations.
Year of Publication: 1981
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
ODP Ocean Drilling Program
Key Words: 02 Geochemistry; Alteration; Analysis; Atlantic Ocean; Basalts; C-13/C-12; Calcite; Carbon; Carbonates; Chemical composition; Clay minerals; DSDP Site 395; Deep Sea Drilling Project; Framework silicates; Geochemistry; Geologic thermometry; Halmyrolysis; IPOD; Igneous rocks; Isotopes; Lava; Leg 109; Leg 45; Leg 78B; North Atlantic Ridge; O-18/O-16; Ocean Drilling Program; Oxygen; Ratios; Saponite; Secondary minerals; Sheet silicates; Silicates; Smectite; Stable isotopes; Temperature; Volcanic rocks; Zeolite group
Coordinates: N224521 N224521 W0460454 W0460454
Record ID: 1981056608
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute.