Morphology and emplacement of flows from the Deccan Volcanic Province, India

Abstract

The present study is probably the first of its kind in the Deccan Volcanic Province (DVP) that deals in detail with the morphology and emplacement of the Deccan Trap flows, and employs modern terminology and concepts of flow emplacement. We describe in detail the two major types of flows that occur in this province. Compound pahoehoe flows, similar to those in Hawaii and the Columbia River Basalts (CRB) constitute the older stratigraphic Formations. These are thick flows, displaying the entire range of pahoehoe morphology including inflated sheets, hummocky flows, and tumuli. In general, they show the same three-part structure associated with pahoehoe flows from other provinces. However, in contrast to the CRB, pahoehoe lobes in the DVP are smaller, and hummocky flows are quite common. 'Simple' flows occur in the younger Formations and form extensive sheets capped by highly vesicular, weathered crusts, or flow-top breccias. These flows have few analogues in other provinces. Although considered to be a'a flows by previous workers, the present study clearly reveals that the simple flows differ considerably from typical a'a flows, especially those of the proximal variety. This is very significant in the context of models of flood basalt emplacement. At the same time, they do not display direct evidence of endogenous growth. Understanding the emplacement of these flows will go a long way in determining whether all extensive flows are indeed inflated flows, as has recently been postulated.Most of the studies relating to the emplacement of Continental Flood Basalt (CFB) lavas have relied on observations of flows from the CRB. Much of the current controversy surrounding the emplacement of CFB flows centers around the comparison of Hawaiian lava flows to those from the CRB. We demonstrate that the DVP displays a variety of lava features that are similar to those from the CRB as well as those from Hawaii. This suggests that there may have been more than one mechanism or style for the emplacement of CFB flows. These need to be taken into account before arriving at any general model for flood basalt emplacement.

Emplacement characteristics, time scales, and volcanic gas release rates of continental flood basalt eruptions on Earth

“…Overall, this is a refl ection of similar eruption conditions and magma types in most provinces. A certain amount of volcanological knowledge exists about the subaerial volcanism that occurred in continental fl ood basalt provinces (e.g., the Deccan province; Bondre et al, 2004), but this does not extend to the intrusive components, except in a couple of cases, i.e., the Karoo-Ferrar province (Svensen et al, 2012;Moulin et al, 2011;Elliot et al, 1999) and the Siberian province (e.g., Svensen et al, 2009;Sobolev et al, 2011).…”

A Mesoproterozoic continental flood rhyolite province, the Gawler Ranges, Australia: the end member example of the Large Igneous Province clan

“…1) what would have probably been a far larger volcanic expression of the system. The dimensions of such a system are characteristic of "classic" mafic large igneous provinces (Bondre et al, 2004;Coffin and Eldholm, 1994;Courtillot et al, 2003;Jerram and Widdowson, 2005;White and Mckenzie, 1995), in which the high magma flux rates and low viscosities enable long lava flow lengths. The radiating morphology of the lobes emanating from a central zone is consistent with that observed in modern shield volcanoes (Thouret, 1999).…”

Caracterização Morfológica E Petrográfica Do Derrame Salto Segredo – Formação Serra Geral, Paraná

“…De acordo com Self et al (1996Self et al ( , 1998, os lençóis de vesículas, ou veios de segregação conforme Bondre et. al.…”

“…O estudo objetiva, ainda, o reconhecimento de feições indicativas dos processos de inflamento e segregação magmática, frequentemente observadas em outras províncias continentais, as chamadas Grandes Províncias Ígneas (Large Igneous Provinces -LIP) como na Província do Deccan, na Índia (Bondre et al 2004, Walker 1969, na Província Columbia River, no Colorado, Estados Unidos (Self et. al.…”