HR: 17:32h
AN: V14A-08 [Abstracts]
TI: Ultra-high Pressure Minerals in Ophiolites
AU: * Robinson, P T
EM: p.robinson@ns.sympatico.ca
AF: Department of Earth Sciences, Dalhousie University, Halifax, NS B3H3J5
Canada
AU: * Robinson, P T
EM: p.robinson@ns.sympatico.ca
AF: Key Laboratory for Continental Dynamics, Institute of Geology,
Chinese Academy of Geological Sciences,
26 Baiwanzhuang Road, Beijing, 100037
China
AU: Bai, W
EM: yangjsui@ccsd.org.cn
AF: Key Laboratory for Continental Dynamics, Institute of Geology,
Chinese Academy of Geological Sciences,
26 Baiwanzhuang Road, Beijing, 100037
China
AU: Yang, J
EM: yangjsui@ccsd.org.cn
AF: Key Laboratory for Continental Dynamics, Institute of Geology,
Chinese Academy of Geological Sciences,
26 Baiwanzhuang Road, Beijing, 100037
China
AU: Fang, Q
EM: yangjsui@ccsd.org.cn
AF: Key Laboratory for Continental Dynamics, Institute of Geology,
Chinese Academy of Geological Sciences,
26 Baiwanzhuang Road, Beijing, 100037
China
AB:
Most ultra-high pressure (UHP) minerals are found in kimberlites, deeply subducted continental crustal rocks and meteorites
or meteorite impact craters. Graphitized diamonds have been found in subcontinental peridotites of the Ronda and Beni
Boursera massifs. Numerous UHP minerals have also been reported from ophiolites, particularly in Russia, Indonesia, Canada,
the USA and China. Many of these reported discoveries are from placer deposits and the origin of the UHP minerals has not
been confirmed. The best documented occurrence of an UHP mineral-bearing ophiolite is the Luobusa ophiolite, which lies in
the Yarlung-Zangbo suture zone of southern Tibet. A wide variety of UHP minerals, including diamond, moissanite, coesite,
Fe-silicides, wstite, silicon rutile, silicon spinel, and CrC alloys, has been recovered from podiform chromitites in
Luobusa. These minerals are associated with native elements, such as Si, Fe, Ti, and Cr, and with PGE alloys, some of which
may also have an UHP origin. Diamonds have also been reported from the Donqiao ophiolite of the Nujiang-Bangong Lake suture
zone in central Tibet but this occurrence as not been confirmed. The demonstrated occurrence of UHP minerals in Luobusa and
the reported occurrences from other bodies suggest that ophiolites may be common repositories of UHP minerals.
DE: 3660 Metamorphic petrology
DE: 3665 Mineral occurrences and deposits
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2004 AGU Fall Meeting