Physical volcanology of the Pavagadh rhyolites, northern Deccan Traps: Stratigraphic, structural, and textural record of explosive and effusive eruptions

Sheikh, Janisar M.; Sheth, Hetu; Naik, Anmol; Keluskar, Tanmay

doi:10.1016/j.jvolgeores.2020.107024

Cited by 13 publications

(10 citation statements)

References 69 publications

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“…15e) are features consistent with forceful uprise of the residual rhyolitic melts, arguably aided by volatile enrichment. Broadly similar crystal aggregates have been described in ignimbrites of the Snake River Plain (Ellis et al 2014) and in the Mount Pavagadh rhyolite lava (Sheikh et al 2020b). Szymanowski et al (2015) find evidence for intermediate to mafic (dioriticgabbroic) mushes stored in mid-crustal reservoirs under the Yellowstone-Snake River Plain province, including a geophysically imaged, 10 km thick, high-density body.…”

Section: A3 Embayed Quartz and Crystal Cargoes Of Mafic Compositionsupporting

confidence: 64%

“…The crystal cargoes of mafic composition common in the rhyolites and vitrophyres of the area (Figs. 14h, i, 15b, c, e-i) are comparable to those in the Mount Pavagadh rhyolite lava and the Chhapariyali rhyolite dyke; they were similarly derived from disaggregation of gabbroic cumulate mushes in magma chambers (see Sheikh et al 2020bSheikh et al , 2023.…”

Section: D Mafic Enclavesmentioning

confidence: 71%

“…However, the numerous examples in the study area (Figs. 4-7), and others described from Mount Pavagadh (Sheikh et al 2020b) and the Alech Hills caldera (Sheth et al 2022a), imply that a significant number of flood rhyolite (and dacite) lavas are present in the northernnorthwestern Deccan Traps.…”

Section: A1 Rheomorphic Rhyolites and Dacitesmentioning

confidence: 82%

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The physical volcanology of large-scale effusive and explosive silicic eruptions in southeastern Saurashtra, Deccan Traps

Naik,

Sheth,

Kumar

et al. 2023

Geol. Mag.

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Silicic magmatism, minor overall in the ∼65.5 Ma Deccan Traps continental flood basalt (CFB) province of India, was widespread in the Saurashtra region. We describe the physical volcanology of silicic volcanics and dykes exposed around Rajula–Savarkundla–Gariyadhar–Talaja towns in southeastern Saurashtra. The silicic volcanics conformably overlie basaltic lavas, suggesting rapid subaerial volcanism, and the sequence shows gentle tectonic dips (∼15°) towards the Arabian Sea. Rhyolites and dacites with preserved thicknesses of tens of metres show intense internal rheomorphic deformation, and a dacite shows a well-formed basal autobreccia. The rheomorphic rhyolites, and vitrophyres which often underlie them, lack vitroclasts (glass shards and pumice clasts). They have very similar mineral assemblages (quartz and alkali feldspar phenocrysts, and crystal cargoes dominated by calcic plagioclase and clinopyroxene or orthopyroxene, sometimes with olivine). The rheomorphic units are thus flood rhyolite and dacite lavas, apparently common in the northern-northwestern Deccan, and the vitrophyres their basal chilled parts. Tuffs (including crystal-vitric Plinian fallout ash) and eutaxitic ignimbrites formed from pyroclastic density currents; one tuff contains extraordinary numbers of lithophysae. Ridges of rhyolitic tuff breccias with pervasive secondary silicification and ferruginization represent pyroclastic eruptive fissures. The area thus records large-scale effusive and explosive silicic eruptions. Mafic and silicic dykes intrude the basaltic lavas and rarely the silicic volcanics. Mafic enclaves in several silicic dykes and some volcanics indicate magma mingling as a common phenomenon. The seaward-dipping volcanic units define a regional-scale flexure comparable to coastal flexures in CFB provinces worldwide, suggesting extensive block-faulting of this classical volcanic rifted margin.

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Section: A3 Embayed Quartz and Crystal Cargoes Of Mafic Compositionsupporting

confidence: 64%

Section: D Mafic Enclavesmentioning

confidence: 71%

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The physical volcanology of large-scale effusive and explosive silicic eruptions in southeastern Saurashtra, Deccan Traps

Naik,

Sheth,

Kumar

et al. 2023

Geol. Mag.

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“…Bryan et al, 2002;Jerram et al, 1999;Ukstins Peate et al, 2005), and can form key correlation and absolute dating targets with important implications for the environmental impact of LIPs. Further explosive eruption deposits of dacite to rhyolite composition with broad similarities in both texture and thickness to those of the RDG have been investigated from field exposures to the south and southeast of RDG (Sheikh et al, 2020a(Sheikh et al, , 2020b, which attests to a potentially wide distribution of such units and highlights the potential importance of these largescale felsic eruptions in the evolution of the early Deccan. Current knowledge suggests the RDG sequence pre-dates the main phase of Deccan volcanism and, therefore, also the K-T boundary, however, high-precision U-Pb age dating appears viable for the RDG and can form a key focus of future study.…”

Section: Seismicmentioning

confidence: 98%

Volcanic facies architecture of early bimodal volcanism of the NW Deccan Traps: Volcanic reservoirs of the Raageshwari Deep Gas Field, Barmer Basin, India

Millett

Jerram

Mund³

et al. 2021

Basin Research

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The Deccan Traps large igneous province (LIP) comprises one of the largest continental flood basalt provinces on Earth with the main phase of volcanism spanning the Cretaceous-Palaeogene boundary. The oldest volcanism of the province is encountered in the northwest of modern-day India where Deccan stratigraphy is often buried beneath thick Cenozoic sedimentary sequences. The Raageshwari Deep Gas (RDG) Field, located onshore in the central Barmer Basin, NW India, produces gas from the early Deccan Raageshwari Volcanics which are subdivided into two members, the Agni Member and the overlying Prithvi Member.The RDG comprises a globally important example of a producing volcanic reservoir whilst also offering unique insights into the early volcanism of the Deccan with the aid of extensive high quality sub-surface data. Within this study, the volcanic facies of the RDG sequences are investigated from five cored intervals (total 160 m). Core-based facies determinations are compared with geochemical analyses, petrophysical analyses of the cores (density, porosity and permeability), and wireline data including micro-resistivity borehole images (FMI) and Nuclear Magnetic Resonance (NMR) data. A wireline based volcanic lithofacies scheme is developed and applied to the uncored parts of the sequence which in turn is compared to 3D seismic data. Results of the study reveal the Agni Member to comprise a compositionally bimodal (basalt through to trachyte), dominantly alkaline series with mixed volcanic facies including spectacular felsic ignimbrites, basic-intermediate simple lava flows, volcaniclastic units and newly identified shallow intrusions. The Prithvi Member in contrast is dominated by tholeiitic basalt compositions with less common basic-intermediate alkaline compositions and comprises a sequence dominated by classic tabular lava flow facies inter-digitated with boles, volcaniclastic units, rare compound braided lava facies and evolved tuffaceous ash layers. In one interval of the Prithvi Member, evidence for agglutinated spatter is recorded inferring potential proximity to a palaeo-eruption site within the area. Comparison between core data and volcanic facies reveals a first order control of volcanic facies on reservoir properties

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“…Some silicic rocks with an intraplate pedigree have been identified in discrete magmatic centers that are broadly associated with the major structural feature of the Narmada-Tapti-Son lineament in centralwestern India (Basu et al, 2020a). Outcrops of these complexes are dominated by plutonic and subvolcanic lithologies, with some explosive and effusive members (e.g., Sheikh et al, 2020;Sheth et al, 2021). While some evolved magma compositions have been attributed to near-closed-system differentiation of DT basalts (e.g., Cucciniello et al, 2019), radiogenic isotope ratios commonly indicate old crustal components (Chatterjee and Bhattacharji, 2001;Sheth and Melluso, 2008;Sheth et al, 2011;Basu et al, 2020a).…”

Section: Character and Location Of Volcanic Sourcesmentioning

confidence: 99%

A red bole zircon record of cryptic silicic volcanism in the Deccan Traps, India

O'Connor

Szymanowski

Eddy

et al. 2022

Geology

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Silicic magmas within large igneous provinces (LIPs) are understudied relative to volumetrically dominant mafic magmas despite their prevalence and possible contribution to LIP-induced environmental degradation. In the 66 Ma Deccan LIP (India), evolved magmatism is documented, but its geographic distribution, duration, and significance remain poorly understood. Zircons deposited in weathered Deccan lava flow tops (“red boles”) offer a means of indirectly studying potentially widespread, silicic, explosive volcanism spanning the entire period of flood basalt eruptions. We explored this record through analysis of trace elements and Hf isotopes in zircon crystals previously dated by U–Pb geochronology. Our results show that zircon populations within individual red boles fingerprint distinct volcanic sources that likely developed in an intraplate setting on cratonic Indian lithosphere. However, our red bole zircon geochemical and isotopic characteristics do not match those from previously studied silicic magmatic centers, indicating that they must derive from yet undiscovered or understudied volcanic centers associated with the Deccan LIP.

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Physical volcanology of the Pavagadh rhyolites, northern Deccan Traps: Stratigraphic, structural, and textural record of explosive and effusive eruptions

Cited by 13 publications

References 69 publications

The physical volcanology of large-scale effusive and explosive silicic eruptions in southeastern Saurashtra, Deccan Traps

The physical volcanology of large-scale effusive and explosive silicic eruptions in southeastern Saurashtra, Deccan Traps

Volcanic facies architecture of early bimodal volcanism of the NW Deccan Traps: Volcanic reservoirs of the Raageshwari Deep Gas Field, Barmer Basin, India

A red bole zircon record of cryptic silicic volcanism in the Deccan Traps, India

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