Not logged in
PANGAEA.
Data Publisher for Earth & Environmental Science

Hasenaka, Toshiaki; Crawford, Anthony J; Briqueu, Louis; Coltorti, Massimo; Baker, Peter E; Fujinawa, A (1994): Chemistry of magmatic samples of ODP Holes 134-832B and 134-833B [dataset publication series]. PANGAEA, https://doi.org/10.1594/PANGAEA.787569, Supplement to: Hasenaka, T et al. (1994): Magmatic evolution of the North Aoba Intra-Arc Basin: Sites 832 and 833. In: Green, HG; Collot, J-Y; Stokking, LB; et al. (eds.), Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 134, 375-392, https://doi.org/10.2973/odp.proc.sr.134.018.1994

Always quote citation above when using data! You can download the citation in several formats below.

RIS CitationBibTeX CitationShow MapGoogle Earth

Abstract:
New petrographic and compositional data were reported for 143 samples of core recovered from Sites 832 and 833 during Ocean Drilling Program (ODP) Leg 134. Site 832 is located in the center and Site 833 is on the eastern edge of the North Aoba Basin, in the central part of the New Hebrides Island Arc. This basin is bounded on the east (Espiritu Santo and Malakula islands) and west (Pentecost and Maewo islands) by uplifted volcano-sedimentary ridges associated with collision of the d'Entrecasteaux Zone west of the arc. The currently active Central Belt volcanic front extends through the center of this basin and includes the shield volcanoes of Aoba, Ambrym, and Santa Maria islands.
The oldest rocks recovered by drilling are the lithostratigraphic Unit VII Middle Miocene volcanic breccias in Hole 832B. Lava clasts are basaltic to andesitic, and the dominant phenocryst assemblage is plagioclase + augite + orthopyroxene + olivine. These clasts characteristically contain orthopyroxene, and show a low to medium K calc-alkaline differentiation trend. They are tentatively correlated with poorly documented Miocene calc-alkaline lavas and intrusives on adjacent Espiritu Santo Island, although this correlation demands that the measured K-Ar of 5.66 Ma for one clast is too young, due to alteration and Ar loss.
Lava clasts in the Hole 832B Pliocene-Pleistocene sequence are mainly ankaramite or augite-rich basalt and basaltic andesite; two of the most evolved andesites have hornblende phenocrysts. These lavas vary from medium- to high-K compositions and are derived from a spectrum of parental magmas for which their LILE and HFSE contents show a broad inverse correlation with SiO2 contents. We hypothesize that this spectrum results from partial melting of an essentially similar mantle source, with the low-SiO2 high HFSE melts derived by lower degrees of partial melting probably at higher pressures than the high SiO2, low HFSE magmas. This same spectrum of compositions occurs on the adjacent Central Chain volcanoes of Aoba and Santa Maria, although the relatively high-HFSE series is known only from Aoba.
Late Pliocene to Pleistocene lava breccias in Hole 833B contain volcanic clasts including ankaramite and augite + olivine + plagioclase-phyric basalt and rare hornblende andesite. These clasts are low-K compositions with flat REE patterns and have geochemical affinities quite different from those recovered from the central part of the basin (Hole 832B). Compositionally very similar lavas occur on Merelava volcano, 80 km north of Site 833, which sits on the edge of the juvenile Northern (Jean Charcot) Trough backarc basin that has been rifting the northern part of the New Hebrides Island Arc since 2-3 Ma.
The basal sedimentary rocks in Hole 833B are intruded by a series of Middle Pliocene plagioclase + augite +/- olivine-phyric sills with characteristically high-K evolved basalt to andesite compositions, transitional to shoshonite. These are compositionally correlated with, though ~3 m.y. older than, the high-HFSE series described from Aoba.
The calc-alkaline clasts in Unit VII of Hole 832B, correlated with similar lavas of Espiritu Santo Island further west, presumably were erupted before subduction polarity reversal perhaps 6-10 Ma. All other samples are younger than subduction reversal and were generated above the currently subduction slab. The preponderance in the North Aoba Basin and adjacent Central Chain islands of relatively high-K basaltic samples, some with transitional alkaline compositions, may reflect a response to collision of the d'Entrecasteaux Zone with the arc some 2-4 Ma. This may have modified the thermal structure of the subduction zone, driving magma generation processes to deeper levels than are present normally along the reminder of the New Hebrides Island Arc.
Project(s):
Ocean Drilling Program (ODP)
Coverage:
Median Latitude: -14.836000 * Median Longitude: 167.726500 * South-bound Latitude: -14.876000 * West-bound Longitude: 167.573000 * North-bound Latitude: -14.796000 * East-bound Longitude: 167.880000
Date/Time Start: 1990-11-23T03:30:00 * Date/Time End: 1990-12-14T00:30:00
License:
Creative Commons Attribution 3.0 Unported (CC-BY-3.0)
Size:
6 datasets

Download Data

Download ZIP file containing all datasets as tab-delimited text — use the following character encoding:

Datasets listed in this publication series

  1. Hasenaka, T; Crawford, AJ; Briqueu, L et al. (1994): (Table 2) Chemistry of olivine from ODP Holes 134-832B and 134-833B. https://doi.org/10.1594/PANGAEA.787559
  2. Hasenaka, T; Crawford, AJ; Briqueu, L et al. (1994): (Table 4) Chemistry of Fe-Ti oxides from ODP Holes 134-832B and 134-833B. https://doi.org/10.1594/PANGAEA.787564
  3. Hasenaka, T; Crawford, AJ; Briqueu, L et al. (1994): (Table 1) Chemistry of plagioclases from ODP Holes 134-832B and 134-833B. https://doi.org/10.1594/PANGAEA.787555
  4. Hasenaka, T; Crawford, AJ; Briqueu, L et al. (1994): (Table 3) Chemistry of pyroxene from ODP Holes 134-832B and 134-833B. https://doi.org/10.1594/PANGAEA.787563
  5. Hasenaka, T; Crawford, AJ; Briqueu, L et al. (1994): (Table 6) Rare earth element compositions of volcanic clast and sill samples of ODP Holes 134-832B and 134-833B. https://doi.org/10.1594/PANGAEA.787566
  6. Hasenaka, T; Crawford, AJ; Briqueu, L et al. (1994): (Table 5) Major and trace element compositions of volcanic clast and sill samples of ODP Holes 134-832B and 134-833B. https://doi.org/10.1594/PANGAEA.787565