Unknown
PANGAEA
In:
Supplement to: Agrinier, Pierre; Mével, Catherine; Girardeau, Jacques (1988): Hydrothermal alteration of the peridotites cored at the ocean/continent boundary of the Iberian margin: petrologic and stable isotope evidence. In: Boillot, G; Winterer, EL; et al. (eds.), Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 103, 225-234, https://doi.org/10.2973/odp.proc.sr.103.136.1988
Publication Date:
2024-01-09
Description:
A ridge of strongly serpentinized, plagioclase-bearing peridotite crops out at the boundary between the Atlantic oceanic crust and the Galicia continental margin (western Spain). These peridotites, cored at Hole 637A (ODP Leg 103) have been mylonitized at high-temperature, low-pressure conditions and under large deviatoric stress during their uplift (Girardeau et al., 1988, doi:10.2973/odp.proc.sr.103.135.1988).
After this main ductile deformation event, the peridotite underwent a polyphase metamorphic static episode in the presence of water, with the crystallization of Ti- and Cr-rich pargasites at high-temperature (800°-900°C) interaction with a metasomatic fluid or alkaline magma. Introduction of water produced destabilization of the pyroxenes and the subsequent development of hornblendes and tremolite at temperatures decreasing from 750° to 350°C. The main serpentinization of the peridotite occurred at a temperature below 300°C, and possibly around 50°C, as a consequence of the introduction of a large amount of seawater, which is suggested by stable isotope (d18O and SD) data. Finally, calcite derived from seawater precipitated in late-formed fractures or locally pervasively impregnated the peridotite at low temperature (~10°C).
Keywords:
103-637A; DRILL; Drilling/drill rig; Joides Resolution; Leg103; Ocean Drilling Program; ODP; South Atlantic Ocean
Type:
Dataset
Format:
application/zip, 3 datasets
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