Petrography, Geochemistry and Intrusion Mechanism of a Deccan Trap Dyke within the Infratrappeans of Temriya Area, Dhar District, Madhya Pradesh

The Cretaceous infratrappean sedimentary rocks in Temriya area, Dhar district, Madhya Pradesh are intruded by Deccan Trap dykes and sills. Petrochemistry reveals that the dyke rocks are basaltic in composition, have tholciitic affinity (01 and/or Qz normative), continental-within plate characters showing moderate iron-enrichment with Mg. No. ranging from 0.28 to 0.42. The dyke shows variable major and trace element concentration and ratios; TiO₂:2.05-2.91%, K₂O: 0.71-0.95%, Ba: 183-346ppm, Nb: <5-19ppm, Sr: 195-285ppm, Zr : 39- 124ppn1, Y 20-32ppm and Rb: 28-38ppm with MgO varying from 3.01 to 5.68% indicating that the magma was subsequently contaminated by selective addition processes from the crust. The rocks show a moderate range in REE abundances and LaIYb ratios with a conspicuous LREE enrichment and HREE depletion. The dyke is genetically related to the Deccan Trap volcanism and was derived from a single source emplaced along tensional fractures probably due to the reactivation of basement lineaments.