dc.contributor.advisor |
Rao, N V Chalapathi |
en_US |
dc.contributor.author |
VERMA, DEVESH |
en_US |
dc.date.accessioned |
2020-06-15T07:16:31Z |
|
dc.date.available |
2020-06-15T07:16:31Z |
|
dc.date.issued |
2020-06 |
en_US |
dc.identifier.uri |
http://dr.iiserpune.ac.in:8080/xmlui/handle/123456789/4706 |
|
dc.description.abstract |
The Proterozoic Harohalli dyke swarm lies in the Dharwar craton. Some of these dykes were sampled from Mysore to investigate the sub-surface geology of the region. Lamprophyre samples were collected since they act as windows to the SCLM.
Microscopy gave characteristic lamprophyric features – panidiomorphic-porphyritic texture with amphibole and clinopyroxene as phenocrysts and feldspar as groundmass. EPMA analysis revealed the presence of two types of amphiboles – magnesiohastingsite (primary) and actinolite (secondary). Diopsidic augite was also present. The lamprophyre was identified to be Vogesite – a calc-alkaline lamprophyre.
The lamprophyres are shoshonitic and high-K in nature. Whole-rock geochemistry showed Nb-Ta-Ti negative anomaly along with Pb, K and Sr enrichment. A negative Hf-Zr anomaly and depletion of HREE was observed. However, due to U depletion, low Mg# and Ni concentration, crustal contamination appeared to be practically absent, and with the help of tectonic discrimination diagrams, a subduction zone tectonic setting has been suggested.
The petrogenesis was pinned down to low degrees of partial melting of subduction fluid-metasomatised depleted mantle followed by high degrees of fractional crystallisation, through discrimination diagrams and petrogenetic modelling. A phlogopite garnet lherzolite source was estimated, and the metasomatized mantle was simulated by mixing average global subducting sediments and depleted mantle. |
en_US |
dc.language.iso |
en |
en_US |
dc.subject |
Western Dharwar Craton |
en_US |
dc.subject |
Shoshonitic Lamprophyres |
en_US |
dc.subject |
Subduction |
en_US |
dc.subject |
2020 |
en_US |
dc.title |
Petrogenesis of Proterozoic Lamprophyres from the Western Dharwar Craton, southern India |
en_US |
dc.type |
Thesis |
en_US |
dc.type.degree |
BS-MS |
en_US |
dc.contributor.department |
Dept. of Earth and Climate Science |
en_US |
dc.contributor.registration |
20151005 |
en_US |