Tectonic significance of dykes in the Sarnu-Dandali alkaline complex, Rajasthan, northwestern Deccan Traps

Vijayan, Anjali; Sheth, Hetu; Sharma, Kamal Kant

doi:10.1016/j.gsf.2015.09.004

Cited by 29 publications

(16 citation statements)

References 41 publications

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“…Rock exposures in these areas are typically intrusive and silica‐undersaturated and include basanites, ijiolites, nepheline syenites, lamprophyres, gabbros, pyroxenites, and carbonatites. Pande et al (); Sheth, Pande, Vijayan, Sharma, and Cucciniello (); and Vijayan, Sheth, and Sharma () have collectively provided new geochemical data, emplacement ages, petrography, and field relations from these complexes. The Mundwara (68.53 ± 0.16 Ma) and Sarnu‐Dandali (68.57 ± 0.08 Ma) complexes have been dated using the 40 Ar– 39 Ar technique on biotite and alkali pyroxenite, respectively (Basu et al, ).…”

Section: Geology and Geochronology Of Amba Dongar Carbonatites And Rementioning

confidence: 99%

Composition and U—Pb ages of apatite in the Amba Dongar carbonatite–alkaline complex, India

et al. 2018

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The Amba Dongar carbonatite‐alkaline complex is regarded as a late phase intrusion (ca. 65 Ma) associated with Deccan volcanism. Existing age constraints on the Amba Dongar carbonatite are based on phlogopite 40Ar–39Ar plateau ages derived from carbonatite and associated alkaline rocks within the complex. We explore the utility of apatite, a common accessory mineral in Amba Dongar carbonatites, as a petrogenetic and geochronological tool to constrain further the evolution of the carbonatites. Apatite exhibits different crystal forms—from hexagonal stubby prisms to ovoid and elongate grains. Apatite occurs as cumulate and disseminated grains that are either primary, fractured, or recrystallized. SrO content is high in primary apatite (3.17 wt%) but less in recrystallized (1.90 wt%) and disseminated grains (0.47 wt%). MnO and Cl are negligible while FeO is typically low in all samples. SiO2 content is low except for a few primary grains which measure up to 1.35 wt%, correlating with high REE content. LREEs dominate the total REE budget of Amba Dongar apatite, with HREEs below EPMA detection limit in most samples. Total REE content is generally low, though some primary apatite contains up to 3.19 wt% REEs. We also report UPb apatite ages from the carbonatites analysed in situ by LA‐ICP‐MS. The data from all samples combined on a UPb Tera–Wasserburg concordia yield a lower intercept age of 65.4 ± 2.5 Ma (MSWD = 2.8, 207Pb/206Pbi = 0.8272 ± 0.0028), and the Amba Dongar carbonatites are thus interpreted to represent a phase of coeval magmatic activity with Deccan volcanism.

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Section: Geology and Geochronology Of Amba Dongar Carbonatites And Rementioning

confidence: 99%

Composition and U—Pb ages of apatite in the Amba Dongar carbonatite–alkaline complex, India

et al. 2018

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“…This also indicates that the precursor magmatism of the Deccan event intruded the eastern margin of Barmer rift basin. Evidence of the Deccan Trap precursor has been reported by some authors from the Sarnoo-Travidar-Dandali areas (Roy 2003;Vijayan et al 2015).…”

Section: Discussionmentioning

confidence: 71%

“…The Fatehgarh Formation-the main reservoir system of the Barmer basin-was exposed along this ENE fault trend. Deccan-related volcanism at a few locations close to Sarnoo and Tavidar/Tavider (Bhushan 2000;Sharma 2007;Sheth 2007;Vijayan et al 2015) relates to reactivation of older crustal fractures within the MIS.…”

Section: Geologymentioning

confidence: 99%

Brittle Shear Tectonics in a Narrow Continental Rift: Asymmetric Nonvolcanic Barmer Basin (Rajasthan, India)

Dasgupta

Mukherjee

2017

The Journal of Geology

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Our field studies emphasizing brittle shear P-and Y-planes along the margins of the Barmer basin (Rajasthan, India) support its two-phase (NW-SE, followed by NE-SW) extension during Early Cretaceous and Late Cretaceous-Paleocene periods. We also document nearly NE-trending megascale transfer zones along the northern margin of the Barmer basin. Preexisting brittle planes in the Malani basement rocks guided the relay structures here. Structures at the western basin shoulder margin indicate NE-SW extension, and the crosscut relation connotes the relative timing of the two extension phases. The crosscutting conjugate fault sets are non-Andersonian. The NW-trending faults produced by the second-phase extension and the inherited NNW-trending brittle features are dominantly dip-slip. Prior fractures of the Malani rocks at ≥457 to the NE-SW principal extension direction extended the Barmer basin obliquely during the Late Cretaceous-Paleocene period. The asymmetric nature of the rift, too, connotes its oblique rifting. The extension direction of the first phase probably rotated clockwise. This is derived mainly from WSW-trending faults cutting NE-trending faults. Brittle planes of shear and fracture significantly promoted fluid flow, as understood from secondary hydrothermal mineral deposits (Barmer hill area) and pre-Deccan basalts (Sarnoo area). Reverse slip detected along subvertical faults on the western and eastern rift shoulders are probably due to isostatic flexure-related contraction or might be related to the farfield effect of ridge-push forces. The Mesozoic subsurface stratigraphy there and elsewhere within the Barmer basin requires more study to substantiate the potential for structural entrapment of hydrocarbon.

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“…These dykes are inferred to have undergone no or little contamination and structural trends of the dykes indicate considerable east-west lithospheric extension during this late, though still magmatically vigorous, stage of Deccan volcanism (Sheth et al, 2014). The mafic dykes associated with the Sarnu-Dandali complex, NW Deccan Traps, are shown not to be controlled by basement structure, but related to contemporaneous, late Cretaceous regional ENE-WSW extension (Vijayan et al, 2016).…”

Section: (I) Phanerozoic Mafic Dykesmentioning

confidence: 90%

Kimberlites, Lamproites, Lamprophyres, Carbonatites, other Alkaline Rocks, and Mafic Dykes from the Indian Shield: Glimpses of Research (2012-2016)

Rao

Srivastava²

2016

Proceedings of the Indian National Science Academy

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Major highlights of researches carried out on kimberlites, lamproites, lamprophyres, carbonatites, other alkaline rocks and mafic dykes from the Indian shield during 2012-2016 are presented. New findings involving field mapping, petrology, geochemistry (including high quality mineral based in situ isotopic studies) and geophysics have provided remarkable insights on the mode of their occurrence, timing of emplacement, mineralogy and bulk-rock composition, redox conditions, relative contribution of the lithosphere and asthenosphere, as well as their economic potential. Several large-scale geodynamic aspects such as plume-lithosphere interactions, ancient subduction events, layered structure of the sub-continental lithospheric mantle, spatial extent of the Precambrian large igneous provinces and supercontinent configurations could be unraveled from these studies on deep-mantle derived small-volume magmatic rocks.

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Tectonic significance of dykes in the Sarnu-Dandali alkaline complex, Rajasthan, northwestern Deccan Traps

Cited by 29 publications

References 41 publications

Composition and U—Pb ages of apatite in the Amba Dongar carbonatite–alkaline complex, India

Composition and U—Pb ages of apatite in the Amba Dongar carbonatite–alkaline complex, India

Brittle Shear Tectonics in a Narrow Continental Rift: Asymmetric Nonvolcanic Barmer Basin (Rajasthan, India)

Kimberlites, Lamproites, Lamprophyres, Carbonatites, other Alkaline Rocks, and Mafic Dykes from the Indian Shield: Glimpses of Research (2012-2016)

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