Mineralogy and magmatic affinity of the jasra intrusive complex, Shillong Plateau, India

Melluso, L. ; Srivastava, R. K. ; Petrone, C. M. ; Guarino, V. ; Sinha, A. K. (2012) Mineralogy and magmatic affinity of the jasra intrusive complex, Shillong Plateau, India Mineralogical Magazine, 76 (5). 1099-1117 . ISSN 0026-461X

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Official URL: http://minmag.geoscienceworld.org/content/76/5/109...

Related URL: http://dx.doi.org/10.1180/​minmag.2012.076.5.03

Abstract

The rocks of the Jasra intrusive complex (Shillong Plateau, northeastern India) include phlogopite clinopyroxenites (with olivine or perovskite relics), alkali gabbros/monzodiorites, syenites and nepheline syenites. They have a potassic affinity (Na2O/K2O ~1), and their mineralogy is dominated by clinopyroxene with which phlogopite, olivine, amphibole, feldspars, feldspathoids, oxides, orthopyroxenes, perovskite, titanite and other accessory phases are variably associated. The Jasra intrusive rocks are cumulates derived from at least two distinct magmatic liquids. The potassic affinity of the Jasra rocks differs from the nearby Sung Valley ijolitic-carbonatitic complex and from the ultrapotassic lamproitic rocks of the Damodar Valley, which are of approximately the same age. This suggests major variability in the mantle sources of small-volume alkaline volcanism in the Early Cretaceous of northeastern India.

Item Type:Article
Source:Copyright of this article belongs to The Mineralogical Society.
Keywords:Clinopyroxenites; Gabbros; Syenites; Perovskite; Titanite; Amphibole; Potassic Rocks; Jasra Intrusion; India
ID Code:96514
Deposited On:21 Dec 2012 12:52
Last Modified:21 Dec 2012 12:52

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