Pedersen, Rolf B; Christie, David M; Pyle, Douglas G (2004): (Table T1) Nd and Sr isotopic compositions, and Nd and Sm concentrations of glasses from ODP Leg 187 sites [dataset]. PANGAEA, https://doi.org/10.1594/PANGAEA.780718, Supplement to: Pedersen, RB et al. (2004): Regional and local mantle heterogeneities associated with the Australian Antarctic Discordance: Sr and Nd isotopic results from ODP Leg 187. In: Pedersen, RB; Christie, DM; Miller, DJ (eds.) Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 187, 1-23, https://doi.org/10.2973/odp.proc.sr.187.205.2004
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Abstract:
The principal objective of Leg 187 was to locate the Indian/Pacific mantle boundary by sampling and analyzing 8- to 28-Ma seafloor basalts to the north of the Australian Antarctic Discordance (AAD). In this paper we present Sr and Nd isotopic data from basaltic glasses recovered from the 13 sites drilled during Leg 187. Our data show that the boundary region is characterized by a gradual east-west increase in 87Sr/86Sr, with a corresponding decrease in 143Nd/144Nd across a 150-km-wide zone located east and west of the 127°E Fracture Zone. The Sr-Nd isotopic composition of glasses therefore confirms the general conclusions derived by the Leg 187 shipboard scientific party in that the mantle boundary follows a west-pointing, V-shaped depth anomaly that stretches across the ocean floor from the Australian to the Antarctic continental margins.
We document that two systematic trends of covariation between 87Sr/86Sr and 143Nd/144Nd can be distinguished, suggesting that the basalts sampled during Leg 187 formed through the interaction of three contrasting source components: (1) a component that lies within the broad spectrum of Indian-type mantle compositions, (2) a boundary component, and (3) a Pacific-type mantle component. The variations in elemental and isotopic compositions indicate that the boundary component represents a distinct mantle region that is associated with the boundary between the Pacific and the Indian mid-ocean-ridge basalt (MORB) sources rather than a dispersed mantle heterogeneity that was preferentially extracted in the boundary region. However, the origin of the boundary component remains an open question. The three components are not randomly intermixed. The Indian and the Pacific mantle sources both interacted with the boundary component, but they seem not to have interacted directly with each other. Large local variability in isotopic compositions of lavas from the mantle boundary region demonstrates that magma extraction processes were unable to homogenize the isotopic contrasts present in the mantle source in this region.
Systematic variations in rare earth element (REE) concentrations across the depth anomaly cannot be explained solely by variations in source composition. The observed variations may be explained by an eastward increase and westward decrease in the degree of melting toward the mantle boundary region, compatible with a cooling of the Pacific mantle and a heating of the Indian mantle toward the mantle boundary.
Project(s):
Ocean Drilling Program (ODP)
Coverage:
Median Latitude: -43.181308 * Median Longitude: 129.184359 * South-bound Latitude: -45.956700 * West-bound Longitude: 126.908300 * North-bound Latitude: -41.271510 * East-bound Longitude: 134.998350
Date/Time Start: 1999-08-12T23:30:00 * Date/Time End: 2000-01-06T09:00:00
Minimum Elevation: -5736.4 m * Maximum Elevation: -4354.0 m
Event(s):
187-1152A * Latitude: -41.897930 * Longitude: 127.006710 * Date/Time Start: 1999-08-12T23:30:00 * Date/Time End: 1999-11-27T11:15:00 * Elevation: -5055.4 m * Penetration: 11.2 m * Recovery: 0.59 m * Location: Indian Ocean * Campaign: Leg187 * Basis: Joides Resolution * Method/Device: Drilling/drill rig (DRILL) * Comment: 1 core; 11.2 m cored; 0 m drilled; 5.3 % recovery
187-1152B * Latitude: -41.897210 * Longitude: 127.007580 * Date/Time Start: 1999-11-27T11:15:00 * Date/Time End: 1999-11-29T00:00:00 * Elevation: -5055.4 m * Penetration: 46.3 m * Recovery: 3.59 m * Location: Indian Ocean * Campaign: Leg187 * Basis: Joides Resolution * Method/Device: Drilling/drill rig (DRILL) * Comment: 5 cores; 23.7 m cored; 0 m drilled; 15.1 % recovery
187-1153A * Latitude: -41.271510 * Longitude: 129.815130 * Date/Time Start: 1999-11-29T00:00:00 * Date/Time End: 1999-12-01T19:00:00 * Elevation: -5581.4 m * Penetration: 274.9 m * Recovery: 1.77 m * Location: Indian Ocean * Campaign: Leg187 * Basis: Joides Resolution * Method/Device: Drilling/drill rig (DRILL) * Comment: 1 core; 7.3 m cored; 0 m drilled; 24.2 % recovery
Parameter(s):
| # | Name | Short Name | Unit | Principal Investigator | Method/Device | Comment |
|---|---|---|---|---|---|---|
| 1 | Event label | Event | ||||
| 2 | Longitude of event | Longitude | ||||
| 3 | Latitude of event | Latitude | ||||
| 4 | Elevation of event | Elevation | m | |||
| 5 | Sample code/label | Sample label | Pedersen, Rolf B | DSDP/ODP/IODP sample designation | ||
| 6 | Strontium-87/Strontium-86 ratio | 87Sr/86Sr | Pedersen, Rolf B | Thermal Ionization Mass Spectrometry (TIMS) | ||
| 7 | Strontium-87/Strontium-86 ratio, error | 87Sr/86Sr e | ± | Pedersen, Rolf B | Thermal Ionization Mass Spectrometry (TIMS) | |
| 8 | Neodymium-143/Neodymium-144 ratio | 143Nd/144Nd | Pedersen, Rolf B | Thermal Ionization Mass Spectrometry (TIMS) | ||
| 9 | Neodymium-143/Neodymium-144 ratio, error | 143Nd/144Nd e | ± | Pedersen, Rolf B | Thermal Ionization Mass Spectrometry (TIMS) | |
| 10 | Samarium-147/Neodymium-144 ratio | 147Sm/144Nd | Pedersen, Rolf B | Thermal Ionization Mass Spectrometry (TIMS) | ||
| 11 | Samarium | Sm | mg/kg | Pedersen, Rolf B | Thermal Ionization Mass Spectrometry (TIMS) | |
| 12 | Neodymium | Nd | mg/kg | Pedersen, Rolf B | Thermal Ionization Mass Spectrometry (TIMS) | |
| 13 | ε-Neodymium | ε-Nd | Pedersen, Rolf B |
License:
Creative Commons Attribution 3.0 Unported (CC-BY-3.0)
Size:
455 data points