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Natural evidence for garnet-spinel transition (GST) in the Earth’s mantle

BenXun Su¹

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1. Department of Lithospheric Evolution, Institue of Geology and Geophysics, Chinese Academy of Sciences

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Document Type:

Manuscript

Date:

Received 19 May 2008 14:31 UTC; Posted 19 May 2008

Subjects:

Earth and Environment

Tags:

• coexistent five-phase peridotite
• garnet peridotite
• garnet-spinel transition
• ultra-high P-T
• lithospheric mantle

Abstract:

This study based on compiled world-wide garnet peridotite data confirms the GST in high P and T conditions, which was obtained from Al-free experimental system (MgO-Cr₂O₃-SiO₂) by Klemme (2004). A new spinel-phase peridotite zone, garnet peridotite discontinuous zone, is defined, and another GST, although no experimental data, is principally and presumably proposed to exist. The garnet inclusion-bearing spinel harzburgite from Lashaine (Tanzania) provides the first evidence for the existence of ultra-high spinel zone and is explained as recrystallized minerals hosting the interacted residue of ancient oceanic lithosphere subducted into the great depth of more than 220km. These previously unexpected findings are generating great challenges to phase transition in extreme conditions and to our understanding of layered-structure of the Earth. In addition, coexistent five-phase peridotite is suggested to be naturally useful tool to constrain the GST.

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This document is licensed to the public under the Creative Commons Attribution 3.0 License

How to cite this document:

Su, BenXun. Natural evidence for garnet-spinel transition (GST) in the Earth’s mantle. Available from Nature Precedings <http://hdl.handle.net/10101/npre.2008.1898.1> (2008)

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Version number	Document title	Date
v2	Posted 22 May 2008

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