Major element composition of concentrate garnets in Proterozoic kimberlites from the Eastern Dharwar Craton,India: Implications on sub-continental lithospheric mantle |
| |
| Institution: | 1. Department of Earth Sciences, Indian Institute of Technology, Powai, Mumbai 400076, India;2. Geological Survey of India, Bandlaguda Complex, Hyderabad 500068, India;3. Department of Earth and Planetary Sciences, University of Allahabad, Allahabad 211 002, India;1. Department of Earth Sciences Indian Institute of Technology Bombay Powai, Mumbai, India, 400076;2. Institute of Earth Sciences, Academia Sinica P.O. Box 1-55, Nankang Taipei, 11529 Taiwan;1. Volcanology & Petrology Laboratory, Department of Earth & Ocean Sciences, The University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada;2. Rio Tinto Exploration Canada Inc., Vancouver, British Columbia, V6C 1S4, Canada;3. Department of Geosciences, California State University Bakersfield, Bakersfield, CA, 93311, USA;4. Department of Earth Sciences, Durham University, South Road, Durham, DH1 3LE, UK;1. Centre of Advanced Study in Geology, Institute of Science, Banaras Hindu University, Varanasi 221005, India;2. Geological Survey of India, Dayanand Sagar College Rd, Kumaraswamy Layout, Bengaluru 560078, India;3. Geological Survey of India, Western Region, Khanij Bhawan, Jhalana Institutional Area, Jaipur 302004, India;1. Department of Geosciences, Eberhard Karls University, Wilhelmstr. 56, 72076 Tübingen, Germany;2. Buskerud, Telemark and Vestfold County Councils, Fylkeshuset, Svend Foynsgt. 9, 3110 Tønsberg, Norway;3. Department of Geociences, University of Oslo, PBox 1047 Blindern, 0316 Oslo, Norway;4. Department of Geology, University of the Free State, 250 Nelson-Mandela-Drive, Bloemfontein 9300, South Africa;1. Cerege, Aix-Marseille université, case 67, 3, place Victor Hugo, 13331 Marseille, cedex 03, France;2. Senckenberg Naturhistorische Sammlungen Dresden, Museum für Mineralogie und Geologie, Sektion Geochronologie, GeoPlasma Lab, Konigsbrücker Landstraße 159, 01109 Dresden, Germany;3. Department of Geology, Faculty of Sciences-Semlalia, Cadi Ayyad University, Prince Moulay Abdellah Boulevard, P.O. Box 2390, Marrakech, Morocco;4. Université d El Jadida, Département de géologie, université Chouaïb Doukkali, BP. 299, 24000 El Jadida, Morocco;5. Université Antilles-Guyane, Campus de Fouillole, laboratoire Large, 97 159 Pointe à Pitre cedex, FWI, France;6. Service géologique du Maroc, Morocco;7. UMR CNRS 2761, Université de Bretagne occidentale, place Nicolas Copernic, 29280 Plouzané, France;8. Institut für Geowissenschaften, Mineralogie, Goethe Universität Frankfurt, Altenhoeferalle 1, 60438 Frankfurt, Germany;9. Geoazur, Université de Nice-Sophia Antipolis, 250, rue A. Einstein, 06560 Valbonne, France;10. Laboratoire Magmas & Volcans, UMR6524 CNRS et Université B. Pascal, 5, rue Kessler, 63038 Clermont-Ferrand, France |
| |
| Abstract: | This study examines the major element composition of mantle-derived garnets recovered from heavy mineral concentrates of several Proterozoic kimberlites of the diamondiferous Wajrakarur Kimberlite Field (WKF) and the almost barren Narayanpet Kimberlite Field (NKF) in the Eastern Dharwar Craton of southern India. Concentrate garnets are abundant in the WKF kimberlites, and notably rare in the NKF kimberlites. Chemical characteristics of the pyropes indicate that the lithology of the sub-continental lithospheric mantle (SCLM) beneath both the kimberlite fields was mainly lherzolitic at the time of kimberlite eruption. A subset of green pyropes from the WKF is marked by high CaO and Cr2O3 contents, which imply contribution from a wehrlitic source. The lithological information on SCLM, when studied alongside geobarometry of lherzolite and harzburgite xenoliths, indicates that there are thin layers of harzburgite within a dominantly lherzolitic mantle in the depth interval of 115–190 km beneath the WKF. In addition, wehrlite and olivine clinopyroxenite occur locally in the depth range of 120–130 km. Mantle geotherm derived from xenoliths constrains the depth of graphite–diamond transition to 155 km beneath the kimberlite fields. Diamond in the WKF thus could have been derived from both lherzolitic and harzburgitic lithologies below this depth. The rarity of diamond and garnet xenocrysts in the NKF strongly suggest sampling of shallower (<155 km depth) mantle, and possibly a shallower source of kimberlite magma than at the WKF. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
