Citation:

dsdp.proc.69.127.1983

Name: (Table 1) Sulfur and oxygen isotopes from two anhydrite samples recovered from DSDP Hole 70-504B
Published: 1983
License: https://creativecommons.org/licenses/by/3.0/

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Abstract:

The first anhydrite reported from oceanic basalts occurs in altered basalts drilled during DSDP Leg 70 from Hole 504B. Anhydrite has been identified in several samples, two of which were studied in detail.

Anhydrite in Sample 504B-40-3 (130-135 cm), which was acquired at 310 meters sub-basement, occurs in a dolerite at the center of a vug rimmed by saponite and calcite. Red iron-hydroxide-rich alteration halos occur from 0 to 310 meters sub-basement; primary sulfides in these halos are oxidized, and the rocks have lost large amounts of sulfur. The anhydrite in this sample has a d34S value of 18.5 per mil, and it is interpreted to have formed from a fluid containing a mixture of seawater sulfate (20.9 per mil) and basaltic sulfur (0 per mil) released during the oxidation of primary sulfides.

Anhydrite in Sample 504B-48-3 (14-18 cm), which was found at 376 meters sub-basement, occurs intergrown with gyrolite at the center of a 1-cm-wide vein that is rimmed by saponite and quartz. At sub-basement depths below 310 meters to the bottom of the Leg 70 section (562 m sub-basement), the rocks exhibit the effects of anoxic alteration with common secondary pyrite. Anhydrite in Sample 504B-48-3 (14-18 cm) has a d34S value of 36.7 per mil, and it is interpreted to have formed from seawater-derived fluids enriched in 34S through sulfate reduction. Temperatures of alteration calculated from oxygen isotope data range from 60 to 100°C. Sulfate reduction may have occurred in situ, or elsewhere at higher temperature, possibly deeper in the crust.

The secondary mineral paragenetic sequence indicates a progressive decrease in Mg and increase in Ca in the circulating fluids. This eventually led to anhydrite formation late in the alteration process.

Project(s):

Deep Sea Drilling Project (DSDP)

Coverage:

Latitude: 1.227000 * Longitude: -83.730000

Date/Time Start: 1979-12-04T00:00:00 * Date/Time End: 1979-12-04T00:00:00

Minimum Elevation: -3460.0 m * Maximum Elevation: -3460.0 m

Event(s):

70-504B * Latitude: 1.227000 * Longitude: -83.730000 * Date/Time: 1979-12-04T00:00:00 * Elevation: -3460.0 m * Penetration: 836.1 m * Recovery: 91.6 m * Campaign: * Basis: Glomar Challenger * Method/Device: Drilling/drill rig (DRILL) * Comment: 40 cores; 328.6 m cored; 18.5 m drilled; 27.9 % recovery

Parameter(s):

#	Name	Short Name	Unit	Principal Investigator	Method/Device
1	Sample code/label	Sample label		Alt, Jeffrey C	DSDP/ODP/IODP sample designation
2	δ34S, anhydrite	δ34S Anh	‰ CDT	Alt, Jeffrey C	see reference(s)
3	δ34S, standard deviation	δ34S std dev	±	Alt, Jeffrey C	see reference(s)
4	δ18O, anhydrite	δ18O Anh	‰ SMOW	Alt, Jeffrey C	Graphite reduction technique (Sakai and Krouse, 1971; Mizutani, 1971)
5	δ18O, anhydrite, standard deviation	δ18O Anh std dev	±	Alt, Jeffrey C	Graphite reduction technique (Sakai and Krouse, 1971; Mizutani, 1971)
6	Laboratory	Lab		Alt, Jeffrey C

License:

Creative Commons Attribution 3.0 Unported (CC-BY-3.0)

Size:

18 data points

Data

Download dataset as tab-delimited text — use the following character encoding:

1 Sample label	2 δ34S Anh [‰ CDT]	3 δ34S std dev [±]	4 δ18O Anh [‰ SMOW]	5 δ18O Anh std dev [±]	6 Lab
70-504B-40-3,130-135	18.9	0.07			McMaster University - Hamilton, Ontario, Canada. Analysis performed by C. E. Rees
70-504B-48-3,14-18	36.7	0.07			McMaster University - Hamilton, Ontario, Canada. Analysis performed by C. E. Rees
70-504B-48-3,14-18	33.7	0.30			University of Karlsruhe - Karlsruhe, Germany. Analysis performed by H. Hubberten
70-504B-48-3,14-18	37.2	0.15	20.6	0.3	University of Miami - Miami, Florida. Analysis performed by E. Saltzman