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

Sheth, Hetu; Naik, Anmol; Sheikh, Janisar M.; Kumar, Alok

doi:10.1007/s00531-021-02119-4

Cited by 2 publications

(7 citation statements)

References 44 publications

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“…Early and recent observations (e.g. Wakhaloo, 1967; Chatterjee, 1969; Krishnamacharlu, 1974; Sheikh et al 2020a, b; Naik et al 2021; Sheth et al 2022a) and those made in the present study together imply that a range of ignimbrite types is present, along with numerous flood rhyolite and dacite lavas, in the northern and northwestern Deccan Traps. As discussed in detail in these recent studies, many striking similarities exist between the effusive-explosive northern-northwestern Deccan silicic volcanism and the much younger (ca.…”

Section: Discussionsupporting

confidence: 78%

“…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: 81%

“…(ii) Saurashtra contains numerous plutonic complexes and ring dykes (Fig. 1), dominated by granophyre-microgranite (Sheth et al 2011(Sheth et al , 2022aCucciniello et al 2019) and gabbro (Chatterjee, 1932;Banerjee et al 2000). The Girnar Complex is dominantly of gabbro and diorite (Mathur et al 1926;Cucciniello et al 2022;Halder et al 2023).…”

Section: A Geological Backgroundmentioning

confidence: 99%

“…Fedden, 1884; Subba Rao, 1971). Both silicic lavas and ignimbrites are recognized in these parts (Wakhaloo, 1967; Krishnamacharlu, 1974; Sheikh et al 2020a, b; Naik et al 2021), as is a giant (30 km-diameter) silicic caldera (Bandopadhyaya, 1976; Sheth et al 2022a).…”

Section: Introductionmentioning

confidence: 99%

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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: Discussionsupporting

confidence: 78%

Section: A1 Rheomorphic Rhyolites and Dacitesmentioning

confidence: 81%

Section: A Geological Backgroundmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Cited by 2 publications

References 44 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

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

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