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Hawkins, James W; Allan, James F (1994): Geochemistry of ODP Leg 135 igneous rock samples [dataset publication series]. PANGAEA, https://doi.org/10.1594/PANGAEA.793048, Supplement to: Hawkins, JW; Allan, JF (1994): Petrologic evolution of Lau Basin Sites 834 through 839. In: Hawkins, J; Parson, L; Allan, J; et al. (eds.), Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 135, 427-470, https://doi.org/10.2973/odp.proc.sr.135.136.1994

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Abstract:
Ocean Drilling Program Leg 135 provided igneous rock cores from six sites drilled on a transect across the Lau Basin between the Lau Ridge remnant arc and the modem spreading ridges of the Central and Eastern Lau Spreading Centers. The drill cores sampled crust from the earliest stage of backarc extension (latest Miocene time, about 6 Ma), and younger crust (late Pliocene, about 3.8-2 Ma, and middle Pleistocene, about 0.64-0.8 Ma). Nearly all of the igneous samples are from tholeiitic basalt flows; many of them are interbedded with arc-composition volcaniclastic sediments. Rock compositions range from olivine-plagioclase-clinopyroxene basalt, with up to 8% MgO, to oceanic andesites with less than 3.2% MgO and silica contents as high as 56%. The oldest rocks recovered are close in composition to rocks formed at the modern Central and Eastern Lau Spreading Centers and have MORB-like characteristics. Generation of the oldest units was coeval with arc-tholeiitic volcanism on the Lau Ridge less than 100 km to the west. The arc and backarc melts came from different mantle sources. At three sites near the center of the basin, the crust is arc-tholeiitic basalt, two-pyroxene basaltic-andesite, and two-pyroxene andesite. These rocks have many similarities to modem Tofua Arc lavas yet they were drilled within 70 km of the MORB-like Eastern Lau Spreading Center. Estimates of the minimum age for these arc-like rocks indicate that they are late Pliocene (about 2 Ma). These ages overlap the age of the nearby Eastern Lau Spreading Center.
The heterogeneous crust of the Lau Basin carries many of the signatures of supra-subduction zone (SSZ) melts but also has a distinct MORB-like component. Mixing between SSZ and MORB mantle sources may explain the variations and the spatial distribution of magma types.
Project(s):
Ocean Drilling Program (ODP)
Coverage:
Median Latitude: -19.518056 * Median Longitude: -177.147859 * South-bound Latitude: -20.827000 * West-bound Longitude: -177.862000 * North-bound Latitude: -18.501000 * East-bound Longitude: -176.500000
Date/Time Start: 1990-12-21T00:00:00 * Date/Time End: 1991-01-24T00:40:00
License:
Creative Commons Attribution 3.0 Unported (CC-BY-3.0)
Size:
10 datasets

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Datasets listed in this publication series

  1. Hawkins, JW; Allan, JF (1994): (Table 4) Representative analyses of bulk rocks from ODP Leg 135 holes. https://doi.org/10.1594/PANGAEA.793047
  2. Hawkins, JW; Allan, JF (1994): (Appendix B) Major and trace element composition of bulk rock from ODP Leg 135 holes. https://doi.org/10.1594/PANGAEA.793038
  3. Hawkins, JW; Allan, JF (1994): (Appendix D) Major element composition of clinopyroxene from ODP Leg 135 holes. https://doi.org/10.1594/PANGAEA.793040
  4. Hawkins, JW; Allan, JF (1994): (Appendix F) Major element composition of Cr-spinel from ODP Leg 135 holes. https://doi.org/10.1594/PANGAEA.793042
  5. Hawkins, JW; Allan, JF (1994): (Appendix G) Major element composition of Cr-spinel from ODP Leg 135 holes. https://doi.org/10.1594/PANGAEA.793043
  6. Hawkins, JW; Allan, JF (1994): (Table 2) Representative glass analyses of ODP Leg 135 holes. https://doi.org/10.1594/PANGAEA.793044
  7. Hawkins, JW; Allan, JF (1994): (Appendix A) Major element composition of glasses from ODP Leg 135 holes. https://doi.org/10.1594/PANGAEA.793037
  8. Hawkins, JW; Allan, JF (1994): (Appendix E) Major element composition of olivine from ODP Leg 135 holes. https://doi.org/10.1594/PANGAEA.793041
  9. Hawkins, JW; Allan, JF (1994): (Appendix C) Major element composition of plagioclase from ODP Leg 135 holes. https://doi.org/10.1594/PANGAEA.793039
  10. Hawkins, JW; Allan, JF (1994): (Table 3) Representative analyses of rocks from ODP Leg 135 holes. https://doi.org/10.1594/PANGAEA.793045