Newly formed phyllosilicates in rock matrices and fractures from CRP-3 core (Antarctica): an electron microscopy study

Authors: Giorgetti, G.; Aghib, F.S.; Livi, K.J.T.; Gaillot, A.C.; Wilson, T.J.

Source: Clay Minerals, Volume 42, Number 1, March 2007 , pp. 21-43(23)

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Abstract:

A scanning and transmission electron microscopy study has been performed on Oligocene glacio-marine sediments, Devonian sandstones, and Jurassic dolerites recovered during CRP-3 drilling in the Ross Sea (Antarctica). Newly formed clay minerals occur in the rock matrices and as fillings in veins and faults which crosscut the whole sequence. Authigenic clays in sediments consist of beidellite-montmorillonite, berthierine/chlorite intergrowths and illite. Al,K-rich smectites and kaolinite occur in the Devonian sandstones. Saponite, berthierine/chlorite intergrowths, and Fe-hydroxides develop in the altered dolerites. Hence, the composition of the secondary phases depends also on the geochemistry of the rock they grow in. Within each sample, the same authigenic minerals form in the matrix and in the vein/fault. Clays precipitated from fluids, with variable f_O₂ values, which circulated in the system during the contemporaneous diagenetic and faulting events.

Keywords: ROSS SEA; CRP-3 CORE; AUTHIGENIC PHYLLOSILICATES; CHLORITE; ILLITE; SMECTITE; SEM; TEM; EELS

Document Type: Research article

DOI: http://dx.doi.org/10.1180/claymin.2007.042.1.03

Publication date: 2007-03-01

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