Retrogressed eclogite (20 kbar, 1020 °C) from the Neoproterozoic Palghat–Cauvery suture zone, southern India


Autoria(s): Sajeev, K; Windley, BF; Connolly, JAD; Kon, Y
Data(s)

01/06/2009

Resumo

The Palghat–Cauvery suture zone in southern India separates Archaean crustal blocks to the north and the Proterozoic Madurai block to the south. Here we present the first detailed study of a partially retrogressed eclogite (from within the Sittampundi anorthositic complex in the suture zone) that occurs as a 20-cm wide layer in a garnet gabbro layer in anorthosite. The eclogite largely consists of an assemblage of coexisting porphyroblasts of almandine–pyrope garnet and augitic clinopyroxene. However, a few garnets contain inclusions of omphacite. Rims and symplectites composed of Na–Ca amphibole and plagioclase form a retrograde assemblage. Petrographic analysis and calculated phase equilibria indicate that garnet–omphacite–rutile–melt was the peak metamorphic assemblage and that it formed at ca. 20 kbar and above 1000 °C. The eclogite was exhumed on a very tight hairpin-type, anticlockwise P–T path, which we relate to subduction and exhumation in the Palghat–Cauvery suture zone. The REE composition of the minerals suggests a basaltic oceanic crustal protolith metamorphosed in a subduction regime. Geological–structural relations combined with geophysical data from the Palghat–Cauvery suture zone suggest that the eclogite facies metamorphism was related to formation of the suture zone. Closure of the Mozambique Ocean led to development of the suture zone and to its western extension in the Betsimisaraka suture of Madagascar.

Formato

application/pdf

Identificador

http://eprints.iisc.ernet.in/21103/1/http___www.sciencedirect.com_science__ob%3DMImg%26_imagekey%3DB6VBP-4VTVR46-2-F%26_cdi%3D5932%26_user%3D512776%26_orig%3Dsearch%26_coverDate%3D06_30_2009%26_sk%3D998289998%26view%3Dc%26wchp%3DdGLbVzz-zSkzV%26md5%3D982a7fb08517.pdf

Sajeev, K and Windley, BF and Connolly, JAD and Kon, Y (2009) Retrogressed eclogite (20 kbar, 1020 °C) from the Neoproterozoic Palghat–Cauvery suture zone, southern India. In: Precambrian Research, 171 (1-4). pp. 23-36.

Publicador

Elsevier Science

Relação

http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VBP-4VTVR46-2&_user=512776&_rdoc=1&_fmt=&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1153029284&_rerunOrigin=google&_acct=C000025298&_version=1&_urlVersion=0&_userid=512776&md5=8dee151042

http://eprints.iisc.ernet.in/21103/

Palavras-Chave #Centre for Earth Sciences
Tipo

Journal Article

PeerReviewed