Basaltic thermal and material inputs in rhyolite petrogenesis: the Chhapariyali rhyolite dyke, Saurashtra, Deccan Traps

Sheikh, Janisar M.; Cucciniello, Ciro; Naik, Anmol; Sheth, Hetu; Duraiswami, Raymond A.

doi:10.1016/j.chemer.2023.125984

Cited by 1 publication

(6 citation statements)

References 39 publications

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“…15i) may mark the parts where the rhyolite magma was chilled in contact with cold country rock. Similar situations have been described in silicic dykes at Chhapariyali (Cucciniello et al 2020;Sheikh et al 2023) and Osham Hill (Naik et al 2021).…”

Section: A2 Pitchstones and Vitrophyressupporting

confidence: 71%

“…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%

“…Mafic enclaves are common in silicic dykes in the area (Fig. 13g, see also Cucciniello et al 2020;Sheikh et al 2023). These indicate the phenomenon of composite intrusion and magma mingling, expected to occur when a relatively hot mafic magma gets injected into cooler but rheologically essentially liquid silicic magma in a chamber or conduit (e.g.…”

Section: D Mafic Enclavesmentioning

confidence: 90%

“…Examples include the N57°-trending, extensively spherulitic Chhapariyali rhyolite dyke with vitrophyric portions (Fig. 13b, Sheikh et al 2023). Another is a N40°-striking rhyolitic dyke at Navagam-Meriyana, with subvertical flow banding and margins that are vitrophyric at places (Fig.…”

Section: Geology and Field Observationsmentioning

confidence: 99%

“…Six identifiable columnar rows are numbered 1 to 6, sample RJ21/22 represents the easternmost columnar row. (b) The Chhapariyali silicic dyke studied by Cucciniello et al (2020) and Sheikh et al (2023). The dyke in the foreground, with a N57° trend, continues as a spine in the hill in the distance, made up of gently dipping basaltic lava flows.…”

Section: Geology and Field Observationsmentioning

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: A2 Pitchstones and Vitrophyressupporting

confidence: 71%

Section: D Mafic Enclavesmentioning

confidence: 71%

Section: D Mafic Enclavesmentioning

confidence: 90%

Section: Geology and Field Observationsmentioning

confidence: 99%

Section: Geology and Field Observationsmentioning

confidence: 99%

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