The Feeder System of the Deccan Traps (India): Insights from Dike Geochemistry

Triggering of the largest Deccan eruptions by the Chicxulub impact

“…In a recent study, Vanderkluysen et al (2011) correlated mapped dike swarms with the various Deccan formations largely on the basis of the geochemical fi ngerprints established from previous work (Beane et al, 1986). In this work, it was possible to identify groups of Deccan formations for which presumed feeder dikes had distinct orientation characteristics, which can in turn be related to differing tectonic stress regimes associated with their emplacement.…”

“…Figure 5 of Beane et al (1986) shows major changes in the SiO 2 , TiO 2 , P 2 O 5 , and various minor-and trace-element signatures. All evidence, including strontium and neodymium isotopic data, suggests that the early Wai Subgroup magmas had less contamination from interaction with the crust than the Lonavala Subgroup (e.g., Mahoney et al, 1982;Lightfoot and Hawkesworth, 1988;Peng et al, 1994;Vanderkluysen et al, 2011), and also much less geochemical variation overall within the Poladpur, Ambenali, and Mahabaleshwar Formations than in lower formations.…”

“…One possible exception occurs in the Mandla Lobe of the northeast Deccan, at Ranipur, 28 km east of Jabalpur, where there is a report of a "large, well preserved fossil of a dinosaur pelvic girdle" in a 2-m-thick sedimentary layer between two basalt units (Kumar et al, 1999). This part of the Deccan Traps has been identifi ed geochemically as composed of Poladpur overlain by Ambenali Formation (Peng et al, 1998;Vanderkluysen et al, 2011). It will be important to determine whether this fossil is articulated and therefore not reworked, and whether it is in the Poladpur or the Ambenali Formation, or some other formation.…”

“…At Jhimili in the Mandla Lobe, 150 km southwest of Jabalpur, Keller et al (2009) found earliest Danian (P1a zone) planktic foraminifera in a 14 m sedimentary unit between two lava fl ows. If these foraminifera are not reworked, and if the underlying basalt belongs to the Ambenali Formation, probably present throughout the Mandla lobe (Peng et al, 1998;Vanderkluysen et al, 2011), this discovery of zone P1a foraminifera would suggest that the Cretaceous-Paleogene boundary and the Ambenali fl ows were nearly time-coincident; geochemical identifi cation of the basalt and environmental analysis of the sediments will thus be critical.…”

Geochemistry and origin of the Neoproterozoic Natkusiak Flood Basalts and related Franklin Sills, Victoria Island, Arctic Canada

“…The majority of well-studied LIPs are of Mesozoic and Cenozoic age, as older records have mostly been destroyed or degraded (Ernst & Bleeker, 2010). Because flood basalts are the products of fissure eruptions, the study of the Franklin sills as potential feeders for the coeval Natkusiak basalts is critical for determining the eruptive source area(s), the lengths of lava flows and the evolution of the magmatic architecture of this CFB province (Renne et al, 1996;Vanderkluysen et al, 2011). Additional factors, such as the intrusive/extrusive ratio and the type and degree of sedimentary rock assimilation may have influenced the environmental impact of Franklin magmatism (Ganino & Arndt, 2009;Sobolev et al, 2011;Black et al, 2014).…”