New Zealand Journal of Geology and Geophysics abstracts

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Altered biotites in the Marlborough Schist, New Zealand?

NICK MORTIMER

Institute of Geological & Nuclear Sciences
Private Bag 1930
Dunedin, New Zealand

TIM LITTLE

School of Earth Sciences
Victoria University of Wellington
P.O. Box 600
Wellington, New Zealand

Abstract  Four samples of weathered greenschist facies greyschist from Marlborough contain minerals that resemble biotite in thin section. Electron microprobe analysis of these minerals indicates that none of them are pristine biotite but are instead oxidised hydrobiotite and/or interlayered phyllosilicates of muscovite/illite, hydrobiotite, chlorite, and/or vermiculite. Even so, the textural relationships, chemical composition, and possible formation mechanisms of the biotite-like minerals are compatible with their derivation from originally fresh metamorphic biotite. It thus seems likely that biotite zone rocks are exposed in the Marlborough Schist.

Keywords  Marlborough; schists; biotite; sheet silicates; metamorphism; weathering

New Zealand Journal of Geology and Geophysics, 1998, Vol. 41: 105-109

0028-8306/98/4101-0105 $7.00/0 (c) The Royal Society of New Zealand 1998

Short communication

PDF file of entire paper: medium quality (1290K); (scanned from paper original: notes about this process)

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