Mineralogy and Petrology of the Sittampundi Complex, Salem District, Madras State, India

Research Article| March 01, 1956 MINERALOGY AND PETROLOGY OF THE SITTAMPUNDI COMPLEX, SALEM DISTRICT, MADRAS STATE, INDIA A. P SUBRAMANIAM A. P SUBRAMANIAM GEOLOGICAL SURVEY OF INDIA, CALCUTTA 13, INDIA Search for other works by this author on: GSW Google Scholar Author and Article Information A. P SUBRAMANIAM GEOLOGICAL SURVEY OF INDIA, CALCUTTA 13, INDIA Publisher: Geological Society of America Received: 02 Feb 1953 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Copyright © 1956, The Geological Society of America, Inc. Copyright is not claimed on any material prepared by U.S. government employees within the scope of their employment. GSA Bulletin (1956) 67 (3): 317–390. https://doi.org/10.1130/0016-7606(1956)67[317:MAPOTS]2.0.CO;2 Article history Received: 02 Feb 1953 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation A. P SUBRAMANIAM; MINERALOGY AND PETROLOGY OF THE SITTAMPUNDI COMPLEX, SALEM DISTRICT, MADRAS STATE, INDIA. GSA Bulletin 1956;; 67 (3): 317–390. doi: https://doi.org/10.1130/0016-7606(1956)67[317:MAPOTS]2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract The mineralogy and petrology of a thoroughly metamorphosed and reconstituted layered complex of anorthositic rocks with associated gabbroic and chromitic facies from Peninsular India are described in detail. This is one of the few known occurrences of highly metamorphosed anorthositic rocks, and the mineral associations are unique. New chemical analyses and optical studies are presented for two plagioclases, three amphiboles, three garnets, and one each of clinozoisite, cordierite, and chromite together with eight chemical analyses of the rocks. Of special interest are the very calcic plagioclases (An80–100) in the anorthosites. Chemical analyses in duplicate of a calcic plagioclase, found to be An100 by optical methods, indicated it to be An98, perhaps the nearest approach in nature to synthetic anorthite. The complex consists of a layered sequence of meta-anorthositic gneisses and eclogite-gabbros, with the former containing layers of chromitite and perknite; by analogy with other described occurrences of stratiform sheets, this is interpreted as a metamorphosed gravity-stratified sheet. A plot of available chemical analyses of garnetiferous metagabbros and eclogites and their associated garnets is given, and the possibility of a compositional field for most true eclogites as distinguished from garnetiferous metagabbros is pointed out. Deformation and mineral reconstitution during two periods of Archean orogeny, following primary crystallization from a basic magma, modified the paragenesis and mineralogy of these rocks with the development of new minerals such as hornblende, anthophyllite, pyralmandite, epidote-clinozoisite, grossularite garnet, porphyroblastic corundum (in part with calcite rims), and chromite with unmixed rutile. It is proposed to call this stratiform sheet “Sittampundi complex” after the village near its type exposure. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.