Significance of Zr-in-Rutile Thermometry for Deducing the Decompression P–T Path of a Garnet–Clinopyroxene Granulite in the Moldanubian Zone of the Bohemian Massif

0480051 - GLÚ 2018 RIV GB eng J - Článek v odborném periodiku
Usuki, T. - Iizuka, Y. - Hirajima, T. - Svojtka, Martin - Lee, H.-Y.
Significance of Zr-in-Rutile Thermometry for Deducing the Decompression P–T Path of a Garnet–Clinopyroxene Granulite in the Moldanubian Zone of the Bohemian Massif.
Journal of Petrology. Roč. 58, č. 6 (2017), s. 1173-1198. ISSN 0022-3530. E-ISSN 1460-2415
Grant ostatní: Program interní podpory projektů mezinárodní spolupráce AV ČR(CZ) M100131203
Program: Program interní podpory projektů mezinárodní spolupráce AV ČR
Institucionální podpora: RVO:67985831
Klíčová slova: Bohemian Massif * P–T path * Zr-in-rutile thermometry * high-pressure granulite * continental collision * garnet–clinopyroxene barometry
Obor OECD: Geology
Impakt faktor: 4.100, rok: 2017

We apply Zr-in-rutile thermometry to a garnet-clinopyroxene (Grt-Cpx) granulite from the Moldanubian Zone of the Bohemian Massif. Three major metamorphic evolutionary stages are identified from the Grt-Cpx granulite. Application of Zr-in-rutile thermometry yields a temperature of ~830 °C at ~1.8 GPa for the early HP stage of granulite evolution. Rutile grains in the clinopyroxene-plagioclase domain of the matrix generally occur as small euhedral crystals and have higher Zr contents, corresponding to 1000–1050 °C at ~1.2 GPa using Zr-in-rutile thermometry. In contrast, those in the quartz-feldspar domains of the matrix occur as coarser and more elongated grains with lower Zr contents, yielding slightly lower temperatures. Si and Zr X-ray compositional mapping by electron microprobe reveals that rutile grains in both the domains were formed in quartz-bearing but zircon-free conditions. Thus, the Zr-in-rutile temperatures obtained for rutile grains in the matrix indicate the minimum estimates. Based on these results, we reveal that the studied Grt-Cpx granulite underwent significant heating by about 200 °C during the early stage of decompression from the peak pressure. This heating was caused by incorporation of the Grt-Cpx granulite into higher temperature felsic granulites rapidly exhumed from deeper parts of the continental collision zone.
Trvalý link: http://hdl.handle.net/11104/0275972