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White, William M; Cheatham, Michael M; Duncan, Robert A (1990): Isotope ratios of basalts from ODP Leg 115 holes (Table 1) [dataset]. PANGAEA, https://doi.org/10.1594/PANGAEA.755690, Supplement to: White, WM et al. (1990): Isotope geochemistry of Leg 115 basalts and inferences on the history of the Réunion Mantle Plume. In: Duncan, RA; Backmann, J; Peterson, LC; et al. (eds.), Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 115, 53-61, https://doi.org/10.2973/odp.proc.sr.115.131.1990

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Abstract:
Strontium, neodymium, and lead isotope ratios are reported for 13 Leg 115 basalts as well as 3 basalts from Texaco drill hole SM-1 on the Mascarene Plateau. The 87Sr/86Sr ratios and eNd range from 0.70330 to 0.70439 and 5.5 to 7.4, respectively, although 87Sr/86Sr ratios higher than 0.70383 are found only in SM-1 basalts. The high 87Sr/86Sr values are thought to reflect seawater Sr in secondary phases, although all samples were strongly leached in HC1 before analysis. 206Pb/204Pb ratios range from 18.53 to 18.80, and sho high 207Pb/204Pb and 208Pb/204Pb ratios relative to 206Pb/204Pb ratios, typical of Indian Ocean mid-ocean ridge (MORB) and oceanic-island basalts (OIB). Isotopic compositions of Leg 115 basalts generally fall between fields for MORB and Reunion Island basalts, consistent with the conclusion drawn from geochronological studies that Deccan flood basalt volcanism, the Chagos-Laccadive Ridge, and the Mascarene Plateau are all products of the Reunion mantle plume. Isotopic compositions of magmas produced by this plume have varied systematically with time in the direction of less "depleted," less MORB-like isotopic signatures. This compositional change has been accompanied by a decrease in eruption rate. We interpret Deccan volcanism as the voluminous beginning of the plume. Reduced entrainment of asthenosphere following melting of the plume head resulted in less MORB-like isotope ratios in magmas and a decrease in eruptive activity with time.
Project(s):
Coverage:
Median Latitude: -6.576960 * Median Longitude: 65.796860 * South-bound Latitude: -13.114000 * West-bound Longitude: 59.016800 * North-bound Latitude: 5.081500 * East-bound Longitude: 73.831300
Date/Time Start: 1987-05-23T08:00:00 * Date/Time End: 1987-06-28T07:45:00
Minimum Elevation: -2920.0 m * Maximum Elevation: -1552.0 m
Event(s):
115-706B * Latitude: -13.114000 * Longitude: 61.371000 * Date/Time Start: 1987-05-23T08:00:00 * Date/Time End: 1987-05-24T03:30:00 * Elevation: -2518.0 m * Penetration: 43.7 m * Recovery: 29.44 m * Location: South Indian Ridge, South Indian Ocean * Campaign: Leg115 * Basis: Joides Resolution * Method/Device: Drilling/drill rig (DRILL) * Comment: 7 cores; 43.7 m cored; 0 m drilled; 67.4 % recovery
115-706C * Latitude: -13.114000 * Longitude: 61.371000 * Date/Time Start: 1987-05-24T03:30:00 * Date/Time End: 1987-05-26T00:45:00 * Elevation: -2518.0 m * Penetration: 121.7 m * Recovery: 19.72 m * Location: South Indian Ridge, South Indian Ocean * Campaign: Leg115 * Basis: Joides Resolution * Method/Device: Drilling/drill rig (DRILL) * Comment: 8 cores; 77.4 m cored; 0 m drilled; 25.5 % recovery
115-707C * Latitude: -7.545300 * Longitude: 59.016800 * Date/Time Start: 1987-05-29T10:30:00 * Date/Time End: 1987-06-02T03:30:00 * Elevation: -1552.0 m * Penetration: 443.2 m * Recovery: 91.56 m * Location: South Indian Ridge, South Indian Ocean * Campaign: Leg115 * Basis: Joides Resolution * Method/Device: Drilling/drill rig (DRILL) * Comment: 27 cores; 259.4 m cored; 0 m drilled; 35.3 % recovery
Parameter(s):
#NameShort NameUnitPrincipal InvestigatorMethod/DeviceComment
1Event labelEvent
2Sample code/labelSample labelWhite, William MDSDP/ODP/IODP sample designation
3Strontium-87/Strontium-86 ratio87Sr/86SrWhite, William M
4Strontium-87/Strontium-86 ratio, error87Sr/86Sr e±White, William M
5Neodymium-143/Neodymium-144 ratio143Nd/144NdWhite, William M
6Neodymium-143/Neodymium-144 ratio, error143Nd/144Nd e±White, William M
7ε-Neodymiumε-NdWhite, William M
8Lead-206/Lead-204 ratio206Pb/204PbWhite, William M
9Lead-206/Lead-204 ratio, error206Pb/204Pb e±White, William M
10Lead-207/Lead-204 ratio207Pb/204PbWhite, William M
11Lead-207/Lead-204 ratio, error207Pb/204Pb e±White, William M
12Lead-208/Lead-204 ratio208Pb/204PbWhite, William M
13Lead-208/Lead-204 ratio, error208Pb/204Pb e±White, William M
Size:
132 data points

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