Widespread rheomorphic and lava-like silicic ignimbrites overlying flood basalts in the northwestern and northern Deccan Traps

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

doi:10.1007/s00445-020-01381-9

Cited by 15 publications

(19 citation statements)

References 46 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…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

View full text Add to dashboard Cite

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

show abstract

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

View full text Add to dashboard Cite

show abstract

“…Eutaxitic ignimbrite has also been described from Bhaguda Hill (Sheikh et al 2020a). The hill exposes brown lava-like rhyolite at the 97 m summit (Fig.…”

Section: D Pitchstones and Vitrophyresmentioning

confidence: 99%

“…This may be the site described by Krishnamacharlu (1974), actually located 2 km northeast of Rajula Junction railway station, though we have not found the three ignimbrite units he described. (Misra, 1976;Kshirsagar et al 2012;Sheikh et al 2020a). (f) View of the escarpment face in the southern part of the Barman Mota Ridge, showing columnar-jointed dacite overlying a highly weathered mafic lava flow (mentioned by Misra (1976) as a trachyandesite).…”

Section: D Pitchstones and Vitrophyresmentioning

confidence: 99%

“…9g-i). Besides the common single lithophysae, there are twins, triplets and even quadruplets (see photos in Misra, 1999;Kshirsagar et al 2012;Sheikh et al 2020a). In addition to the megascopic examples of spherulites and lithophysae, microscopic ones are found in many of the rock units and are described below.…”

Section: F Spherulites and Lithophysaementioning

confidence: 99%

“…(h, i) Eutaxitic ignimbrites in the Bhaguda Hill; 2.5 cm wide coin and hand for scale. See alsoSheikh et al (2020a).…”

mentioning

confidence: 99%

See 2 more Smart Citations

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

Naik,

Sheth,

Kumar

et al. 2023

Geol. Mag.

Self Cite

View full text Add to dashboard Cite

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.

show abstract

Giant (30 km-diameter) silicic caldera of K/Pg boundary age in the northwestern Deccan Traps: the Alech Hills, Saurashtra

Sheth

Naik

Sheikh

et al. 2021

Int J Earth Sci (Geol Rundsch)

View full text Add to dashboard Cite

Widespread rheomorphic and lava-like silicic ignimbrites overlying flood basalts in the northwestern and northern Deccan Traps

Cited by 15 publications

References 46 publications

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

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

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

Giant (30 km-diameter) silicic caldera of K/Pg boundary age in the northwestern Deccan Traps: the Alech Hills, Saurashtra

Contact Info

Product

Resources

About