Porter, Sean; Vanko, David A; Ghazi, Mohamad (2000): Geochemical composition and atomic formulas of saponites, celadonites and clays from ODP Leg 168 sites [dataset publication series]. PANGAEA, https://doi.org/10.1594/PANGAEA.788900, Supplement to: Porter, S et al. (2000): Major and trace element compositions of secondary clays in basalts altered at low temperature, eastern flank of the Juan de Fuca Ridge. In: Fisher, A; Davis, EE; Escutia, C (eds.) Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 168, 1-9, https://doi.org/10.2973/odp.proc.sr.168.004.2000
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Abstract:
A drilling transect across the sedimented eastern flank of the Juan de Fuca Ridge, conducted during Leg 168 of the Ocean Drilling Program, resulted in the recovery of samples of volcanic basement rocks (pillow basalts, massive basalts, and volcanic glass breccias) that exhibit the effects of low-temperature hydrothermal alteration. Secondary clays are ubiquitous, with Mg-rich and Fe-rich saponite and celadonitic clays commonly accounting for several percent, and up to 10%-20% by volume. Present-day temperatures of the basement sites vary from 15° to 64°C, with the coolest site being about 0.8 Ma, and the warmest site being about 3.5 Ma. Whereas clays are abundant at sites that have been heated to present temperatures of 23°C and higher, the youngest site at 15°C has only a small trace of secondary clay alteration. Alteration increases as temperatures increase and as the volcanic basement ages.
The chemical compositions of secondary clays were determined by electron microprobe, and additional trace element data were determined by both conventional nebulization inductively coupled plasma-mass spectroscopy (ICP-MS) and laser-ablation ICP-MS. Trioctahedral saponite and pyrite are characteristic of the interior of altered rock pieces, forming under conditions of low-oxygen fugacity. Dioctahedral celadonite-like clays along with iron oxyhydroxide and Mg-saponite are characteristic of oxidized haloes surrounding the nonoxidized rock interiors. Chemical compositions of the clays are very similar to those determined from other deep-sea basalts altered at low temperature. The variable Mg:Fe of saponite appears to be a systematic function both of the Mg:Fe of the host rock and the oxidation state during water-rock interaction.
Project(s):
Ocean Drilling Program (ODP)
Coverage:
Median Latitude: 47.795823 * Median Longitude: -127.998208 * South-bound Latitude: 47.756500 * West-bound Longitude: -128.792000 * North-bound Latitude: 47.917300 * East-bound Longitude: -127.731000
Date/Time Start: 1996-06-23T09:15:00 * Date/Time End: 1996-08-11T11:57:00
License:
Creative Commons Attribution 3.0 Unported (CC-BY-3.0)
Size:
4 datasets
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Datasets listed in this publication series
- Porter, S; Vanko, DA; Ghazi, M (2000): (Table T4) Geochemical composition of a saponite vein from ODP Hole 168-1026B. https://doi.org/10.1594/PANGAEA.788899
- Porter, S; Vanko, DA; Ghazi, M (2000): (Table T2) Major element oxides and atomic formulas of celadonite from ODP Holes 168-1026B and 168-1027C. https://doi.org/10.1594/PANGAEA.788897
- Porter, S; Vanko, DA; Ghazi, M (2000): (Table T3) Geochemical composition of bulk clays from ODP Leg 168 sites. https://doi.org/10.1594/PANGAEA.788898
- Porter, S; Vanko, DA; Ghazi, M (2000): (Table T1) Major element oxides and atomic formulas of saponite from ODP Leg 168 sites. https://doi.org/10.1594/PANGAEA.788896