Petrology and major oxide geochemistry of mafic dykes from Mysore district, Western Dharwar Craton, Karnataka, India

Determining the petrogenetic origins, source characteristics, and geodynamic implications of the Palaeoproterozoic mafic dykes from the WDC is largely dependent on their geochemical composition. Understanding Proterozoic dykes has been the subject of numerous investigations due to their crucial role in the history of crustal evolution. As dykes have great significance in exemplifying the crustal evolution history, their geochemical and geophysical properties have gained attention among geoscientists. An attempt is made here to understand such WDC mafic dykes from Mysore district, through its petrographical and major oxide geochemical studies. Mafic dykes from the study area exhibit N-S and NNW-SSE trending intrusion within in the PGC. Dolerite, gabbro, and meta-dolerites are the three types of dyke rocks that were collected from the research region based on their mineralogical, textural, and geochemical properties. The collected dyke samples have a doleritic composition with prominent lath-shaped plagioclase and Cpx minerals. A few dolerite dykes have sulfide mineralization, such as pyrite, also magnetite and chalcopyrite crystals. The mafic properties of the gathered dyke samples are validated by geochemical plots. The dyke rocks display a tholeiite nature and have ferro-magnesium enrichment. Based on the TAS plot, the composition of dolerites can be interpreted as basaltic to basaltic andesitic. There is a positive association between the MgO and compatible elements . All of these observations support the mafic nature of these rocks and distinguish them as gabbro, dolerite, and meta-dolerite dyke bodies. Strong OIB and E-MORB affinity is reflected in the tectonic setting diagram, most likely as a result of the emplacement of these mafic dykes in an island arc setting. This study has brought out the basic classification, mineralogy and tectonic setting of these dykes found in Mysore district.