Publication Date:
2019-09-23
Description:
During cruise SO201-1b of the joint Russian–German expedition on the R/V Sonne in 2009,
mantle peridotites affected by varying secondary alteration were dredged on the eastern slope of the north-
western segment of the Stalemate transverse ridge adjacent to the eponymous fracture zone. The collection
discussed in this paper included four samples of silicified serpentinites after dunites and 11 lherzolite samples
serpentinized to a varying degree. The abundance of amorphous silica and quartz, very high SiO2 content (up
to 88.7 wt %), and unusually low MgO (up to 1.4 wt %) in the serpentinized dunites strongly distinguish these
rocks from the known products of hydrothermal alteration and low-temperature (seafloor) weathering of
peridotites in the oceanic crust. In order to determine the conditions and processes resulting in the silicifica-
tion of peridotites at the Stalemate Fracture Zone, thermodynamic modeling accounting for the kinetics of
mineral dissolution implemented in the GEOCHEQ program package was used in this study. The results of
modeling allowed us to suppose that the geochemical and mineralogical effects observed in the silicified ser-
pentinized dunites of the Stalemate Fracture Zone are consequences of low-temperature deserpentinization
of oceanic materials under subaerial conditions.
Type:
Article
,
PeerReviewed
Format:
text
DOI:
10.1134/S0869591112010055