The peridotites beneath arc outcrop at the inner slop of the Mariana Trench because of subduction erosion, which provides us a window to see the geological process in mantle wedge. In this paper, mineral composition, major elements, and trace element data of the peridotites dragged from southern Mariana Trench inner slope are reported to discuss petrogeness and fluid/rock interaction. High Mg of olivine, extremely low Al2O3 of orthopyroxene, and high Cr of spinel indicate the peridotites are refractory. Hydrous minerals in the peridotites such as Talc, amphibole (mainly tremolite with a little magnesiohornblende and edenite) and serpentine indicate fluid that might be rich in SiO2, Na2O and Al2O3 interacting with the refractory peridotites in mantle wedge. Whole rocks contain low concentration of CaO and Al2O3 and high MgO (~43% calculate to anhydrous system) coincidence with refractory nature revealed by mineral composition. The relative enrichment of U and Sr might reflect the chemical characteristics of the fluid released from the subducting slab at shallow depth.
DONG Pan-Hui
,
CHU Feng-You
,
SHU Ji-Gao
,
TU Xing
. Petrology and geochemistry of peridotite dredged from inner slope of Southern Mariana Trench: implication for mantle fluid metasomatism in the forearc setting[J]. Journal of Tropical Oceanography, 2012
, 31(3)
: 120
-127
.
DOI: 10.11978/j.issn.1009-5470.2012.03.016
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