Petrology, geochemistry and paleomagnetism of the earliest magmatic rocks of Deccan Volcanic Province, Kutch, Northwest India

Paul, D. K.; Ray, Arijit; Das, Brindaban; Patil, Shrikant; Biswas, Sanjib

doi:10.1016/j.lithos.2007.08.005

Cited by 49 publications

(21 citation statements)

References 39 publications

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“…During the later stage, the igneous activity related to the Reunion plume responsible for Deccan Traps might have injected more ultramafic material. These signatures manifest in the form of dykes, sills, plugs, laccoliths, and ring dykes are in conformity with the idea that the Mesozoic rocks of the Kachchh basin were affected by intense magmatic activities [ Paul et al , ]. The tholeiitic basalt flows disconformably overlie the Mesozoic rocks.…”

Section: Discussionmentioning

confidence: 99%

Crust beneath the northwestern Deccan Volcanic Province, India: Evidence for uplift and magmatic underplating

2015

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The northwestern Deccan Volcanic Province of India and its pericratonic rift basins were reactivated during different stages after the breakup of India from the Gondwanaland and collision with the Asian plate. In this study, we present results of crustal thickness and average crustal V p /V s ratios beneath this plume-affected region using common conversion point imaging and H-k stacking analysis of 6893 receiver functions using data from a network comprising 58 broadband seismic stations sited on diverse tectonic terrains. We find large variations in crustal thickness, with the Moho depths varying from 28 to 43 km in the Kachchh rift, 28 to 38 km in the Cambay rift, 39.5-41.5 km in the north and eastern parts of the Cambay rift, and 29 to 39 km in the Saurashtra region and South Gujarat. A Moho upwarp of 6 to 7 km in the Saurashtra region can be attributed to positive buoyancy and uplift due to thermal influx affected by the Reunion plume. High crustal V p /V s ratios beneath the Kachchh rift (1.8 to 2.05), coastal areas of Saurashtra (1.75 to 2.06), and North Gujarat (1.81 to 1.85) indicate dominance of a mafic/ultramafic crust. High regional heat flow, high electrical conductivity, large intracrustal S wave velocity reduction, and high average crustal Poisson's ratios are consistent with partial melt related to the process of magmatic underplating in the lower crust. At other stations, the crust appears to be felsic with V p /V s ratios in the range of 1.57 to 1.76.

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Section: Discussionmentioning

confidence: 99%

Crust beneath the northwestern Deccan Volcanic Province, India: Evidence for uplift and magmatic underplating

2015

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“…The present location (latitude) of these dykes are ∼23.5 • N and the region between Laxmi and Gop Basins ∼19.5 • N. This suggests that not much movement has taken place between the Kutch Rift Basin and the Laxmi Ridge after their formation; also the volcanic flows in the region north of LR and dykes in the Kutch Basin may be contemporaneous. The magmatic activity in the Kutch Rift Basin leading to the formation of these dykes is coeval with the Deccan lava eruption (Paul et al 2008). From the isotopic and chemical compositions of the basalts from the Kutch and Mumbai Offshore Basins, Rathore et al (2013), suggest that the basalts in these basins falls to Within Plate Basalts (WPB) category similar to on-land Deccan trap.…”

Section: Resultsmentioning

confidence: 99%

A relook into the crustal architecture of Laxmi Ridge, northeastern Arabian Sea from geopotential data

et al. 2015

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In this study, we undertake analysis of ship-borne gravity-magnetic and satellite-derived free-air gravity (FAG) data to derive the crustal structure of Laxmi Ridge and adjacent areas. 2D and 3D crustal modelling suggests that the high resolution FAG low associated with the ridge is due to underplating and that it is of continental nature. From Energy Spectral Analysis, five-depth horizons representing interface between different layers are demarcated that match those derived from 2D models. Magnetic sources from EMAG2 data, various filtered maps and absence of underplating in the EW section suggest that the EW and NW-SE segment of the Laxmi Ridge is divided by the Girnar fracture zone and probably associated with different stages of evolution. From the derived inclination parameters, we infer that the region to the north of Laxmi Ridge, between Laxmi and Gop Basins, is composed of volcanic/basaltic flows having Deccan affinity, which might have been emplaced in an already existing crust. The calculated inclination parameters derived from the best fit 2D model suggests that the rifting in the Gop Basin preceded the emplacement of the volcanics in the region between Laxmi and Gop Basins. The emplacement of volcanic/basaltic flows may be associated with the passage of India over the Reunion hotspot.

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“…The structural uplifts of northern Kachchh expose many plugs, sills and dikes of alkali basalt, basanite, and gabbro. These have been studied in terms of petrology and geochemistry Das et al 2007;Paul et al 2008), but no geochronological data on these exist, whereas there have been several petrological, geochemical and age dating studies of the central Kachchh mafic alkalic rocks and their mantle nodules (De 1981;Mukherjee and Biswas 1988;Pande et al 1988;Krishnamurthy et al 1988Krishnamurthy et al , 1999Simonetti et al 1998;Karmalkar et al 2005;Sen et al 2009). The central Kachchh rocks are alkali basalts, basanites and melanephelinites, with a few nephelinites, and their mantle nodules, generally up to 1 cm (rarely 4 cm) in size, are of spinel wehrlite, spinel lherzolite and dunite.…”

Section: Geology Of the Deccan Traps And Kachchhmentioning

confidence: 99%

“…2) indicate that the plugs were emplaced at the same time as the major Deccan tholeiitic outpourings to the south, including southern Kachchh itself. Many intrusions of alkali basalt, basanite and gabbro outcrop in the Jurassic sandstone-limestone uplifts of northern Kachchh (e.g., Pachcham Island, Ray et al 2006;Paul et al 2008), and west-northwest of Nakhatrana (Guha et al 2005). We believe that future dating work will prove them to be of Deccan age.…”

Section: The Age and Size Of The Of Central Kachchh Monogenetic Volcamentioning

confidence: 99%

Mafic alkalic magmatism in central Kachchh, India: a monogenetic volcanic field in the northwestern Deccan Traps

2010

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Magmatism in Kachchh, in the northwestern Deccan continental flood basalt province, is represented not only by typical tholeiitic flows and dikes, but also plug-like bodies, in Mesozoic sandstone, of alkali basalt, basanite, melanephelinite and nephelinite, containing mantle nodules. They form the base of the local Deccan stratigraphy and their volcanological context was poorly understood. Based on new and published field, petrographic and geochemical data, we identify this suite as an eroded monogenetic volcanic field. The plugs are shallow-level intrusions (necks, sills, dikes, sheets, laccoliths); one of them is known to have fed a lava flow. We have found local peperites reflecting mingling between magmas and soft sediment, and the remains of a pyroclastic vent composed of non-bedded lapilli tuff breccia, injected by mafic alkalic dikes. The lapilli tuff matrix contains basaltic fragments, glass shards, and detrital quartz and microcline, with secondary zeolites, and there are abundant lithic blocks of mafic alkalic rocks. We interpret this deposit as a maar-diatreme, formed due to phreatomagmatic explosions and associated wall rock fragmentation and collapse. This is one of few known hydrovolcanic vents in the Deccan Traps. The central Kachchh monogenetic volcanic field has >30 individual structures exposed over an area of ∼1,800 km 2 and possibly many more if compositionally identical igneous intrusions in northern Kachchh are proven by future dating work to be contemporaneous. The central Kachchh monogenetic volcanic field implies low-degree mantle melting and limited, periodic magma supply. Regional directed extension was absent or at best insignificant during its formation, in contrast to the contemporaneous significant directed extension and vigorous mantle melting under the main area of the Deccan flood basalts. The central Kachchh field demonstrates regional-scale volcanological, compositional, and tectonic variability within flood basalt provinces, and adds the Deccan Traps to the list of such provinces containing monogenetic-and/or hydrovolcanism, namely the Karoo-Ferrar and Emeishan flood basalts, and plateau basalts in Saudi Arabia, Libya, and Patagonia.

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Petrology, geochemistry and paleomagnetism of the earliest magmatic rocks of Deccan Volcanic Province, Kutch, Northwest India

Cited by 49 publications

References 39 publications

Crust beneath the northwestern Deccan Volcanic Province, India: Evidence for uplift and magmatic underplating

Crust beneath the northwestern Deccan Volcanic Province, India: Evidence for uplift and magmatic underplating

A relook into the crustal architecture of Laxmi Ridge, northeastern Arabian Sea from geopotential data

Mafic alkalic magmatism in central Kachchh, India: a monogenetic volcanic field in the northwestern Deccan Traps

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