Recurrent Lamprophyre Magmatism in the Narmada Rift Zone: Petrographic and Mineral Chemistry Evidence from Xenoliths in the Eocene Dongargaon Lamprophyre, NW Deccan Large Igneous Province, India

Abstract

We report rare occurrence of lamprophyre xenoliths within
a host lamprophyre from the Dongargaon area, Deccan Large Igneous
Province, NW India. The lamprophyre xenoliths are distinct in texture
(grain size) as well in mineralogy from those of their host rock. The
clinopyroxene (diopside) in the xenoliths is depleted in Ca and Mg but
substantially enriched in Fe compared to those in the host lamprophyre.
Mica in the xenoliths is a phlogopite whereas that present in the host
rock is compositionally a biotite; spinels in the host lamprophyre are relatively
enriched in TiO2.
As the host lamprophyre dyke has been dated to
be of Eocene (ca. 55 Ma) age, the entrained lamprophyre xenoliths are
inferred to represent an earlier pulse of lamprophyre emplacement. The
recurrent lamprophyre emplacement in this domain is consistent with the
recently brought out polychronous nature of Late Cretaceous alkaline
magmatism at the Mundwara and Sarnu Dandali complexes in the NW
India and is related to the extensional events linked with the reactivation
of the Narmada rift zone.