Rift-associated ultramafic lamprophyre (damtjernite) from the middle part of the Lower Cretaceous (125 Ma) succession of Kutch, northwestern India: Tectonomagmatic implications

Petrogenesis of lamprophyres synchronous to kimberlites from the Wajrakarur kimberlite field: Implications for contrasting lithospheric mantle sources and geodynamic evolution of the eastern Dharwar Craton of southern India

“…(b) Ca (a.p.f.u) versus Ti (a.p.f.u) tectonic discrimination diagram (after Sun & Bertrad, 1991) for clinopyroxenes suggesting dominantly non-orogenic affinity. Data sources: Cuddapah intrusive province lamprophyres (Madhvan et al, 1998), Mudigubba lamprophyre (Pandey, Chalapathi Rao, Dhote, et al, 2017), ultramafic lamprophyre of Kutch , and Deccan lamprophyres (Chalapathi Rao, Wu, Mitchell, Li, & Lehmann, 2013;Hari, 1998) in the present study and which were recovered from the UKL are given in Table 4 and Figure 12. The zircons are characterized by subhedral to euhedral, elongated prismatic shape and generally very large grain size ranging from 100 to 375 μm.…”

“…Low Nb and Ta concentrations, coupled with high Nb/Ta, can be generated in a mantle source containing subducted continental crust, where interaction between peridotitic mantle and fluids (with high concentration of LREE but depleted in Nb and Ta) took place (e.g., Fan, Guo, Wang, & Zhang, ). The subduction‐related calc‐alkaline Mudigubba lamprophyre dykes display well‐defined negative bulk rock Nb and Ta anomalies and high Nb/Ta ratios of 20–30, which are considered to be mostly source related (Pandey, Chalapathi Rao, Dhote, et al, ). Considering that the high bulk rock SPL and UKL Nb/Ta ratios are unlikely to be explainable through the fractionation of rutile and/or crustal contamination, we propose that the observed elevated Nb/Ta ratios and the negative anomalies observed for Nb, Ta, and Ti on primitive mantle‐normalized bulk rock spidergrams are mostly related to the nature, composition, and evolution of their mantle source.…”

“…(b) Ca (a.p.f.u) versus Ti (a.p.f.u) tectonic discrimination diagram (after Sun & Bertrad, ) for clinopyroxenes suggesting dominantly non‐orogenic affinity. Data sources: Cuddapah intrusive province lamprophyres (Madhvan et al, ), Mudigubba lamprophyre (Pandey, Chalapathi Rao, Dhote, et al, ), ultramafic lamprophyre of Kutch (Pandey, Chalapathi Rao, Pandit, et al, ), and Deccan lamprophyres (Chalapathi Rao, Wu, Mitchell, Li, & Lehmann, ; Hari, ) [Colour figure can be viewed at wileyonlinelibrary.com]…”

“…Petrological aspects such as rock petrography, mineral chemistry, geochemistry, and isotopic compositions (Sr and Nd) are considered with comparison made with other previously recognized and studied analogous rock types from other (different) tectonic settings on the Indian subcontinent. Lamprophyres included in the comparison comprises those of the Cuddapah intrusive province (Madhvan, David, Rao, Chalapathi Rao, & Srinivas, ), the Mudigubba lamprophyre (Pandey, Chalapathi Rao, Dhote, et al, ), the Kutch ultramafic lamprophyre (Pandey, Chalapathi Rao, Pandit, et al, ), and various Deccan lamprophyres (Chalapathi Rao, Dharma Rao, & Das, ; Hari, ). A review of recently reported lamprophyre dykes from the Dharwar Craton and the Deccan province is also presented.…”

Mineralogy and petrology of shoshonitic lamprophyre dykes from the Sivarampeta area, diamondiferous Wajrakarur kimberlite field, Eastern Dharwar craton, southern India

“…Lamprophyres towards the western margin of the Cuddapah basin are relatively less studied compared to those from the Prakasam Alkaline Province at the eastern margin. Recent studies (Pandey et al, 2017a(Pandey et al, , 2017b(Pandey et al, , 2018a(Pandey et al, , 2018bRaghuvanshi et al 2019) on lamprophyres from the western margin of the Cuddapah basin have brought out involvement of three distinct mantle source domains in their genesis; (a) Domain I: represented by orogenic calc-alkaline and/or shoshonitic lamprophyres (e.g., Mudigubba, Udiripikonda, and Kadiri) derived from the SCLM, (b) Domain II: represented by orogenic-anorogenic, alkaline to calc-alkaline lamprophyres (e.g., Korakkodu) sampling mixed orogenic-anorogenic transitional source, and (iii) Domain III: represented by alkaline lamprophyres (e.g., Ankiraopalle) displaying a strong OIB type (asthenospheric) overprint on the SCLM source (see Giri et al 2019). The present study on the Sivarampeta lamprophyre dykes, located within diamondiferous Mesoproterozoic-Late Cretaceous Wajrakarur kimberlite field (WKF), assumes importance in this context.…”