Kawahata, Hodaka; Kusakabe, Minoru; Kikuchi, Yoshiko (1987): Strontium, oxygen and hydrogen isotope ratios of basalts from DSDP Hole 504B [dataset publication series]. PANGAEA, https://doi.org/10.1594/PANGAEA.712352, Supplement to: Kawahata, H et al. (1987): Strontium, oxygen, and hydrogen isotope geochemistry of hydrothermally altered and weathered rocks in DSDP Hole 504B, Costa Rica Rift. Earth and Planetary Science Letters, 85(4), 343-355, https://doi.org/10.1016/0012-821X(87)90132-4
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Abstract:
DSDP Hole 504B was drilled into 6 Ma crust, about 200 km south of the Costa Rica Rift, Galapagos Spreading Center, penetrating 1.35 km into a section that can be divided into four zones--Zone I: oxic submarine weathering; Zone II: anoxic alteration; Zones III and IV: hydrothermal alteration to greenschist facies. In Zone III there is intense veining of pillow basalts. Zone IV consists of altered sheeted dikes. Isotopic geochemical signatures in relation to the alteration zones are recorded in Hole 504B, as follows:
Zone Depth(m) Average87Sr/86Sr Average delta18O ( per mil ) Average deltaD ( per mil )
I 275-550 0.7032 7.3 -63
II 550-890 0.7029 6.5 -45
III 890-1050 0.7035 5.6 -31
IV 1050-1350 0.7032 5.5 -36
Alteration temperatures are as low as 10°C in Zones I and II based on oxygen isotope fractionation. Strontium isotopic data indicate that a circulation of seawater is much more restricted in Zone II than in Zone I. Fluid inclusion measurements of vein quartz indicate the alteration temperature was mainly 300 +/- 20°C in Zones III and IV, which is consistent with secondary mineral assemblages.
The strontium, oxygen, and hydrogen isotopic compositions of hydrothermal fluids which were responsible for the greenschist facies alteration in Zones III and IV are estimated to be 0.7037, 2 per mil , and 3 per mil , respectively. Strontium and oxygen isotope data indicate that completely altered portions of greenstones and vein minerals were in equilibrium with modified seawater under low water/rock ratios (in weight) of about 1.6. This value is close to that of the end-member hydrothermal fluids issuing at 21°N EPR.
Basement rocks are not completely hydrothermally altered. About 32% of the greenstones in Zones III and IV have escaped alteration. Thus 1 g of fresh basalt including the 32% unaltered portion are required in order to make 1 g of end-member solution from fresh seawater in water-rock reactions.
Project(s):
Deep Sea Drilling Project (DSDP)
Coverage:
Median Latitude: 1.227107 * Median Longitude: -83.730107 * South-bound Latitude: 1.227000 * West-bound Longitude: -83.730200 * North-bound Latitude: 1.227200 * East-bound Longitude: -83.730000
Date/Time Start: 1979-10-07T00:00:00 * Date/Time End: 1982-01-02T00:00:00
Event(s):
69-504B * Latitude: 1.227200 * Longitude: -83.730200 * Date/Time: 1979-10-07T00:00:00 * Elevation: -3460.0 m * Penetration: 489 m * Recovery: 262 m * Campaign: Leg69 * Basis: Glomar Challenger * Method/Device: Drilling/drill rig (DRILL)
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: Leg70 * Basis: Glomar Challenger * Method/Device: Drilling/drill rig (DRILL) * Comment: 40 cores; 328.6 m cored; 18.5 m drilled; 27.9 % recovery
83-504B * Latitude: 1.227200 * Longitude: -83.730200 * Date/Time Start: 1981-11-22T00:00:00 * Date/Time End: 1982-01-02T00:00:00 * Elevation: -3460.0 m * Penetration: 1350 m * Recovery: 107.7 m * Campaign: Leg83 * Basis: Glomar Challenger * Method/Device: Drilling/drill rig (DRILL) * Comment: Leg 83 of DSDP was devoted entirely to coring and experiments in Hole 504B, the deepest borehole to date into the oceanic crust. Hole 504B now extends over a kilometer into basement, nearly twice as far as any other DSDP hole, and it is the only DSDP hole to have clearly penetrated into the intrusive sheeted dikes that underlie the extrusive pillow lavas of the upper oceanic crust. At Hole 504B, Leg 83 continued an ongoing DSDP effort that began during Legs 68, 69, and 70 in 1979, and also included part of Leg 92 in 1983. 71 cores; 514 m cored; 0 m drilled; 21 % recovery
License:
Creative Commons Attribution 3.0 Unported (CC-BY-3.0)
Size:
3 datasets
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Datasets listed in this publication series
- Kawahata, H; Kusakabe, M; Kikuchi, Y (1987): (Table 1) Properties and hydrothermal alteration of DSDP Hole 504B. https://doi.org/10.1594/PANGAEA.712349
- Kawahata, H; Kusakabe, M; Kikuchi, Y (1987): (Table 3) Modal analyses of secondary minerals in weathered and hydrothermal altered rocks from DSDP Hole 504B. https://doi.org/10.1594/PANGAEA.712351
- Kawahata, H; Kusakabe, M; Kikuchi, Y (1987): (Table 2) Sr, O and D isotope ratios and water content of altered basement rocks and veins of DSDP Hole 504B. https://doi.org/10.1594/PANGAEA.712350