Ozawa, Kazuhito; Meyer, Peter S; Bloomer, Sherman H (1991): Mineralogy and textures of gabbros from ODP Hole 118-735B [dataset publication series]. PANGAEA, https://doi.org/10.1594/PANGAEA.757443, Supplement to: Ozawa, K et al. (1991): Mineralogy and textures of iron-titanium oxide gabbros and associated olivine gabbros from Hole 735B. In: Von Herzen, RP; Robinson, PT; et al. (eds.), Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 118, 41-73, https://doi.org/10.2973/odp.proc.sr.118.125.1991
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Abstract:
Abundant iron-titanium (Fe-Ti) oxide gabbro, olivine gabbro, and troctolite were drilled at Hole 735B adjacent to the Atlantis II Fracture Zone of the Southwest Indian Ridge during Leg 118. The Fe-Ti oxide gabbro occurs as intrusive bodies into olivine gabbro with very sharp intrusive contacts. The size of the intrusive bodies varies from a millimeter to a few tens of meters. Mineralogical parameters, such as anorthite content of plagioclase and Mg/(Mg+Fe) ratios of mafic minerals exhibit bimodal distributions corresponding to olivine and Fe-Ti oxide gabbros, respectively. When the two major gabbro types are looked at separately, several downhole mineralogical cycles are recognized. The Fe-Ti oxide gabbros exhibit two such cycles with plagioclase becoming more sodic and mafic minerals becoming more iron-rich downward in the drill core. The olivine gabbros and troctolites, however, exhibit two cycles showing an upward increase in sodium in plagioclase and iron in mafic minerals. The mineralogical variations of these gabbros and the intrusive contact relationships probably resulted from downward intrusion of evolved magma into underlying solid or almost solidified olivine gabbros and troctolite. The dense evolved melt at the top of the cumulus pile probably formed from the crystallization of olivine gabbro cumulates followed by extreme fractional crystallization of residual melt in an isolated, ephemeral magma chamber. The interlayered occurrence of evolved and primitive gabbros from Hole 735B represents a typical section of lower ocean crust formed at a very slow spreading ridge.
Project(s):
Ocean Drilling Program (ODP)
Coverage:
Latitude: -32.724000 * Longitude: 57.266200
Date/Time Start: 1987-12-06T04:45:00 * Date/Time End: 1987-12-11T01:00:00
Event(s):
118-735B * Latitude: -32.724000 * Longitude: 57.266200 * Date/Time Start: 1987-12-06T04:45:00 * Date/Time End: 1987-12-11T01:00:00 * Elevation: -731.0 m * Penetration: 500.7 m * Recovery: 434.81 m * Location: South Indian Ridge, South Indian Ocean * Campaign: Leg118 * Basis: Joides Resolution * Method/Device: Drilling/drill rig (DRILL) * Comment: 88 cores; 500.7 m cored; 0 m drilled; 86.8 % recovery
License:
Creative Commons Attribution 3.0 Unported (CC-BY-3.0)
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6 datasets
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Datasets listed in this publication series
- Ozawa, K; Meyer, PS; Bloomer, SH (1991): (Table 5) Average chemical composition of clinopyroxene in gabbros from ODP Hole 118-735B. https://doi.org/10.1594/PANGAEA.757441
- Ozawa, K; Meyer, PS; Bloomer, SH (1991): (Table 1) Petrography of Fe-Ti oxide gabbros from ODP Hole 118-735B. https://doi.org/10.1594/PANGAEA.757430
- Ozawa, K; Meyer, PS; Bloomer, SH (1991): (Table 2) Composition and magnesium numbers of 118-735B gabbros. https://doi.org/10.1594/PANGAEA.757436
- Ozawa, K; Meyer, PS; Bloomer, SH (1991): (Table 3) Average chemical composition of olivine in gabbros from ODP Hole 118-735B. https://doi.org/10.1594/PANGAEA.757438
- Ozawa, K; Meyer, PS; Bloomer, SH (1991): (Table 6) Average chemical composition of orthopyroxene in gabbros from ODP Hole 118-735B. https://doi.org/10.1594/PANGAEA.757442
- Ozawa, K; Meyer, PS; Bloomer, SH (1991): (Table 4) Average chemical composition of plagioclase in gabbros from ODP Hole 118-735B. https://doi.org/10.1594/PANGAEA.757439