Japan Geoscience Union Meeting 2015

Presentation information


Symbol S (Solid Earth Sciences) » S-CG Complex & General

[S-CG58] Petrology, Mineralogy and Resource Geology

Mon. May 25, 2015 4:15 PM - 6:00 PM 203 (2F)

Convener:*Akira Miyake(Department of Geology and Mineralogy, Graduate School of Science, Kyoto University), Toshiaki Tsunogae(Faculty of Life and Environmental Sciences (Earth Evolution Sciences), University of Tsukuba), Koichiro Fujinaga(Department of Systems Innovation, School of Engineering, University of Tokyo), Nobutaka Tsuchiya(Department of Geology, Faculty of Education, Iwate University), Chair:Akira Miyake(Department of Geology and Mineralogy, Graduate School of Science, Kyoto University)

5:57 PM - 6:00 PM

[SCG58-P11] Metamorphic P-T evolution of garnet-clinopyroxene rocks from the Gondwana collisional orogen in southern India

3-min talk in an oral session

*Minami YANO1, Toshiaki TSUNOGAE2, Minako IINUMA2, M SANTOSH3 (1.Univ. Tsukuba, 2.Univ. Tsukuba, 3.China Univ. Geosci.)

Keywords:granulite, P-T path, Gondwana

The East African - Antarctic Orogenic Belt, which includes Madagascar - Southern India - Sri Lanka - East Antarctica regions, is regarded to have been formed by complex subduction-accretion-collision tectonic events related to the amalgamation of Gondwana Supercontinent during Neoproterozoic. The Palghat-Cauvery Suture Zone in southern India is known as a major suture zone that formed during the closure of Mozambique Ocean at ca. 530-550 Ma. The dominant lithologies of the suture zone are felsic to intermediate orthogneiss, metasediments, and mafic-ultramafic suites. Particularly, the occurrence of mafic-ultramafic suites (ophiolite or layered intrusion) is a unique character of the suture zone compared to surrounding granulite blocks and cratons. Here, we report new petrological data of metagabbroic garnet-clinopyroxene rocks from southern India and discuss its petrological implications. Mineral assemblages of the rocks are garnet + clinopyroxene + ilmenite + plagioclase + quartz with retrograde hornblende. Similar rocks and textures have been reported from the Palghat-Cauvery Suture Zone in South India (Nishimiya et al., 2008; Saitoh et al., 2011), Highland Complex in Sri Lanka (Osanai et al., 2006; Takamura et al., 2014), and Lutzow-Holm Complex in East Antarctica (Saitoh et al., 2012). However, temperature and pressure conditions inferred for the metagabbro based on geothermobarometry are 680-710C and ~9 kbar, which is significantly lower than the results of previous studies (>12 kbar, >800C). The metagabbro could be an exotic block with discrete P-T evolution trapped during the formation of the Palghat-Cauvery Suture Zone.