Abstract
Northern part of Eastern Dharwar Craton (EDC) in Karnataka is essentially a granitoid country, frequently intruded by diabase dykes of varied dimensions. Compositionally, majority of them are constituted by pyroxene and plagioclase and less frequently they are olivine-bearing types. One of the major dykes near Thinthini is intensely altered and contains sulfide mineralization brought out by episodic hydrothermal process. Geochemically they are slightly on the higher side of silica content, except the olivine bearing dykes. Their sulfur endowment is also higher. Various discrimination diagrams suggest that they are broadly tholeiitic in composition formed from the less differentiated magma derived from mantle at relatively greater depth and intruded into the granitic rocks which in turn were formed in a subduction setting. The structural deformation prior to and post dating dyke intrusion as deciphered from detailed field studies, alteration of country rocks and hydrothermal activity in the area provide a good background to explore sulfide and other associated metals and also to understand the likely extension of the known mineralized zones.
Highlights
Dharwar Craton in India is made up of granites and greenstones
Swarms in the southern part of the craton [3], and are relatively lesser in occurrence, yet make a significant presence in the northern parts of the craton as well. They are frequently seen intruding the granitic rocks in northern part of Eastern Dharwar Craton (EDC), especially around Thinthini (Figure 1)
The diabase dykes in the northern part of EDC belong to a single stage intrusive activity within the vast sea of granitoids
Summary
Dharwar Craton in India is made up of granites and greenstones. Based on broader lithology, structural features and geodynamic setting this craton is divided into western and eastern Dharwar Cratons (WDC and EDC) [1] [2]. They are frequently seen intruding the granitic rocks in northern part of EDC, especially around Thinthini (Figure 1). There are both mineralized and unmineralised dykes. Very few studies have been carried out for this area, especially on the diabase dykes and mineralization episode [4]. The representative samples were subjected for petrographic and geochemical studies and the results of these studies along with the results of field investigation have been interpreted to understand the petrogenetic and mineralization aspects of the diabase dykes
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