87Sr/86Sr ratios, Sr and Rb concentrations and stable oxygen isotope values for some basalts from ODP Hole 504B (Table 1)
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| Formato: | Dataset Open Access |
| Lenguaje: | en |
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PANGAEA
1982
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| _version_ | 1867169008992649216 |
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| author | Barrett, T J Friedrichsen, Hans |
| author_facet | Barrett, T J Friedrichsen, Hans |
| collection | Datos científicos de ciencias marinas y ambientales |
| contents | Seventeen whole-rock samples, generally taken at 25-50 m intervals from 5 to 560 m sub-basement in Hole 504B, drilled in 6.2 m.y. old crust, were analysed for 87Sr/86Sr ratios, Sr and Rb concentrations, and 18O/16O ratios. Sr isotope ratios for 8 samples from the upper 260 m of the hole range from 0.70287 to 0.70377, with a mean of 0.70320. In the 330-560 m interval, 5 samples have a restricted range of 0.70255-0.70279, with a mean of 0.70266, the average value for fresh mid-ocean ridge basalts (MORB). In the 260-330 m interval, approximately intermediate Sr isotopic ratios are found. Delta18O values (‰) range from 6.4 to 7.8 in the upper 260 m, 6.2-6.4 in the 270-320 m interval, and 5.8-6.2 in the 320-560 m interval. The values in the upper 260 m are typical for basalts which have undergone low-temperature seawater alteration, whereas the values for the 320-560 m interval correspond to MORB which have experienced essentially no oxygen isotopic alteration. The higher 87Sr/86Sr and 18O/16O ratios in the upper part of the hole can be interpreted as the result of a greater overall water/rock ratio in the upper part of the Hole 504B crust than in the lower part. Interaction of basalt with seawater (87Sr/86Sr = 0.7091) increased basalt 87Sr/86Sr ratios and produced smectitic alteration products which raised whole-rock delta18O values. Seawater circulation in the lower basalts may have been partly restricted by the greater number of relatively impermeable massive lava flows below about 230 m sub-basement. These flows may have helped to seal off lower basalts from through-flowing seawater. |
| format | Dataset Open Access |
| id | pangaea_https___doi_org_10_1594_PANGAEA_711004 |
| institution | PANGAEA |
| language | en |
| publishDate | 1982 |
| publisher | PANGAEA |
| record_format | pangaea |
| spellingShingle | 87Sr/86Sr ratios, Sr and Rb concentrations and stable oxygen isotope values for some basalts from ODP Hole 504B (Table 1) Barrett, T J Friedrichsen, Hans 69-504B; 70-504B; Alteration; Deep Sea Drilling Project; DRILL; Drilling/drill rig; DSDP; DSDP/ODP/IODP sample designation; Event label; Glomar Challenger; Isotope ratio mass spectrometry; Leg69; Leg70; Lithology/composition/facies; ORDINAL NUMBER; Rubidium; Sample code/label; Sample code/label 2; Strontium; Strontium-87/Strontium-86 ratio; Strontium-87/Strontium-86 ratio, error; Water in rock; X-ray fluorescence (XRF); δ18O Seventeen whole-rock samples, generally taken at 25-50 m intervals from 5 to 560 m sub-basement in Hole 504B, drilled in 6.2 m.y. old crust, were analysed for 87Sr/86Sr ratios, Sr and Rb concentrations, and 18O/16O ratios. Sr isotope ratios for 8 samples from the upper 260 m of the hole range from 0.70287 to 0.70377, with a mean of 0.70320. In the 330-560 m interval, 5 samples have a restricted range of 0.70255-0.70279, with a mean of 0.70266, the average value for fresh mid-ocean ridge basalts (MORB). In the 260-330 m interval, approximately intermediate Sr isotopic ratios are found. Delta18O values (‰) range from 6.4 to 7.8 in the upper 260 m, 6.2-6.4 in the 270-320 m interval, and 5.8-6.2 in the 320-560 m interval. The values in the upper 260 m are typical for basalts which have undergone low-temperature seawater alteration, whereas the values for the 320-560 m interval correspond to MORB which have experienced essentially no oxygen isotopic alteration. The higher 87Sr/86Sr and 18O/16O ratios in the upper part of the hole can be interpreted as the result of a greater overall water/rock ratio in the upper part of the Hole 504B crust than in the lower part. Interaction of basalt with seawater (87Sr/86Sr = 0.7091) increased basalt 87Sr/86Sr ratios and produced smectitic alteration products which raised whole-rock delta18O values. Seawater circulation in the lower basalts may have been partly restricted by the greater number of relatively impermeable massive lava flows below about 230 m sub-basement. These flows may have helped to seal off lower basalts from through-flowing seawater. |
| title | 87Sr/86Sr ratios, Sr and Rb concentrations and stable oxygen isotope values for some basalts from ODP Hole 504B (Table 1) |
| topic | 69-504B; 70-504B; Alteration; Deep Sea Drilling Project; DRILL; Drilling/drill rig; DSDP; DSDP/ODP/IODP sample designation; Event label; Glomar Challenger; Isotope ratio mass spectrometry; Leg69; Leg70; Lithology/composition/facies; ORDINAL NUMBER; Rubidium; Sample code/label; Sample code/label 2; Strontium; Strontium-87/Strontium-86 ratio; Strontium-87/Strontium-86 ratio, error; Water in rock; X-ray fluorescence (XRF); δ18O |
| url | https://doi.org/10.1594/PANGAEA.711004 |