K-T magmatism and basin tectonism in western Rajasthan, India, results from extensional tectonics and not from Réunion plume activity

Sharma, Kamal Kant

doi:10.1130/2007.2430(35)

Cited by 17 publications

(19 citation statements)

References 20 publications

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“…A mantle-plume origin for the Deccan Traps has been questioned, with many aspects of the Deccan geology inconsistent with that predicted by the plume-head model (Sheth, 2005a(Sheth, , 2005b(Sheth, , 2007, and we suggest that the two non-coaxial episodes of rifting observed within early deposits of the Barmer Basin are better explained by a model of plate reorganisations that initiated long before the arrival of the R eunion Mantle Plume (e.g. Sharma, 2007;Collier et al, 2008). This, combined with a lack of evidence for significant pre-Deccan regional unconformities, and only minor Deccan-age volcanism within the Barmer Basin (Basu et al, 1993;Sen et al, 2012), suggests that rifting did not occur above anomalously hot asthenosphere, despite the rift being situated within the inferred limits of the R eunion plume-head (Fig.…”

Section: Regional Context and Implicationsmentioning

confidence: 62%

“…Evidence for post-volcanic uplift -not confined to the Deccan province -with antecedent drainage patterns, long-lived ( 8e9 Ma) eruptions (Sheth and Pande, 2014), pre-Deccan planation surfaces that suggest tectonic stability, a 10 R eunion Mantle Plume palaeolatitude disparity, and a lack of evidence for thinned, sub-Deccan lithosphere, are all inconsistent with the plume-head model (Sheth, 2005a(Sheth, , 2007. Seychelles rifting is also suggested to have resulted from plate reorganisations underway long before the arrival of the R eunion Mantle Plume (Sharma, 2007;Collier et al, 2008) and continued after the main Deccan eruptions (Armitage et al, 2011). Similarly, rather than being formed as part of the Reunion Mantle Plume 'tail,' the Mascarene Plateau (and possibly LakshadweepChagos Ridge) may be underpinned by thinned Proterozoic continental lithosphere that was situated between the Greater Indian and Madagascan continents prior to successful separation (Torsvik et al, 2013).…”

Section: Plate Tectonic Settingmentioning

confidence: 99%

“…Mesozoic rift events throughout northwest India are attributed to successive stages of India's northwards drift, accompanied by an anti-clockwise rotation of the Greater Indian continent, and formed a network of failed rift-basins that opened sequentially from north to south (Biswas, 1982(Biswas, , 1987Gombos et al, 1995;Sheth, 2005a). Rifting was longlived, possibly beginning as early as the late Triassic Period, and involved multiple rift events that continued into the Paleogene Period (Biswas, 1982;Sharma, 2007). East and west Gondwana separated during the early to middle Jurassic Period, facilitated by opening of the Mozambique and Somali proto-oceans ( Fig.…”

Section: Plate Tectonic Settingmentioning

confidence: 99%

“…The Barmer-Cambay Rift System, therefore, is long-lived and mostly resulted from external plate boundary forces generated as the western margin of the Greater Indian continent fragmented during isolation from east Gondwana, and in the wake of the continent's rapid northwards migration throughout Cretaceous and Paleogene times (e.g. Sharma, 2007). The common assumption that the R eunion Mantle Plume triggered rifting throughout west India at the Cretaceous-Paleogene boundary (Morgan, 1971;Plummer and Belle, 1995;Sen and Chandrasekharam, 2011) is not consistent with the interpretation presented herein of early northwestesoutheast extension within the Barmer Basin, or the formation of a pre-Deccan Barmer-Cambay Rift System.…”

Section: Regional Context and Implicationsmentioning

confidence: 99%

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Complex rift geometries resulting from inheritance of pre-existing structures: Insights and regional implications from the Barmer Basin rift

Bladon

Clarke

Burley

2015

Journal of Structural Geology

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a b s t r a c t Structural studies of the Barmer Basin in Rajasthan, northwest India, demonstrate the important effect that pre-existing faults can have on the geometries of evolving fault systems at both the outcrop and basin-scale. Outcrop exposures on opposing rift margins reveal two distinct, non-coaxial extensional events. On the eastern rift margin northwest-southeast extension was accommodated on southwest and west-striking faults that form a complex, zig-zag fault network. On the western rift margin northeast-southwest extension was accommodated on northwest-striking faults that form classical extensional geometries.Combining these outcrop studies with subsurface interpretations demonstrates that northwest-southeast extension preceded northeast-southwest extension. Structures active during the early, previously unrecognised extensional event were variably incorporated into the evolving fault systems during the second. In the study area, an inherited rift-oblique fault transferred extension from the rift margin to a mid-rift fault, rather than linking rift margin fault systems directly. The resultant rift margin accommodation structure has important implications for early sediment routing and depocentre evolution, as well as wider reaching implications for the evolution of the rift basin and West Indian Rift System. The discovery of early rifting in the Barmer Basin supports that extension along the West Indian Rift System was long-lived, multi-event, and likely resulted from far-field plate reorganisations.

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Section: Regional Context and Implicationsmentioning

confidence: 62%

Section: Plate Tectonic Settingmentioning

confidence: 99%

Section: Plate Tectonic Settingmentioning

confidence: 99%

Section: Regional Context and Implicationsmentioning

confidence: 99%

See 2 more Smart Citations

Complex rift geometries resulting from inheritance of pre-existing structures: Insights and regional implications from the Barmer Basin rift

Bladon

Clarke

Burley

2015

Journal of Structural Geology

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“…Morgan, 1971;Plummer & Belle, 1995;Simonetti et al, 1995). However, alternative views suggest that Seychelles rifting resulted from external plate boundary forces (Sheth, 2005a;Sharma, 2007;Collier et al, 2008;Bladon et al, 2015), and many aspects of the Deccan geology have been shown to be inconsistent with plume activity, being more typical of deep-seated rifting (Sheth, 2005a(Sheth, ,b, 2007Sharma, 2007). In addition, the thick sequence of late Cretaceous to Eocene sediments (>6 km) in the Barmer Basin is counter to the impingement of a mantle plume beneath northwest India near to the Cretaceous-Paleogene boundary, despite the presence of multiple rift-related unconformities within the rift.…”

Section: Geological Backgroundmentioning

confidence: 99%

Geology and regional significance of the Sarnoo Hills, eastern rift margin of the Barmer Basin, NW India

et al. 2015

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The Barmer Basin is a poorly understood rift basin in Rajasthan, northwest India. Exposures in the Sarnoo Hills, situated along the central eastern rift margin of the Barmer Basin, reveal a sedimentary succession that accumulated prior to the main Barmer Basin rift event, and a rift-oblique fault network that displays unusual geometries and characteristics. Here, we present a comprehensive study of Lower Cretaceous sedimentology on the basin margin, along with a detailed investigation of riftoblique faults that are exposed nowhere else in the region and provide critical insights into Barmer Basin evolution. Lower Cretaceous sediments were deposited within a rapidly subsiding alluvial plain fluvial system. Subsequent to deposition, the evolving Sarnoo Hills fault network was affected by structural inheritance during an early, previously unrecognised, rift-oblique extensional event attributed to transtension between India and Madagascar, and formed a juvenile fault network within the immediate rift-margin footwall. Ghaggar-Hakra Formation deposition may have been triggered by early rifting which tectonically destabilised the Marwar Craton prior to the main northeast-southwest Barmer Basin rift event. The identification of early rifting in the Barmer Basin demonstrates that regional extension and the associated rift systems were established throughout northwest India prior to the main phase of Deccan eruptions. Inheritance of early oblique fault systems within the evolving Barmer Basin provides a robust explanation for poorly understood structural complications interpreted in the subsurface throughout the rift. Critically, the presence of syn-rift sedimentary successions within older oblique rift systems obscured beneath the present-day Barmer Basin has significant implications for hydrocarbon exploration. INTRODUCTIONDespite being a significant structure within the West Indian Rift System (Fig. 1a), and an important hydrocarbon province (Dolson et al., 2015), the structural geology and evolution of the Barmer Basin rift remains relatively poorly understood. The current understanding of rift evolution is based predominantly upon subsurface data sets, where an abundance of complex structures and rift-oblique faults are variably imaged on seismic data throughout the rift (Bladon et al., 2015; Fig. 1b). However, the origin of these structures remains elusive, and limited exposure of the structure and stratigraphy of the rift at outcrop has restricted outcrop-based studies. This work characterises a rift-oblique fault network that is apparent nowhere else in the region, and is exposed on the eastern rift margin of the Barmer Basin, in the Sarnoo Hills. Detailed sedimentological and structural analyses are used to clarify the origin of similar rift-oblique faults imaged in the Barmer Basin subsurface, and subsequently to place the findings within the wider context of northwest India. Sediments were deposited in a maturing fluvial system within a rapidly subsiding continental alluvial plain environment. The expos...

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Plates vs. Plumes

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K-T magmatism and basin tectonism in western Rajasthan, India, results from extensional tectonics and not from Réunion plume activity

Cited by 17 publications

References 20 publications

Complex rift geometries resulting from inheritance of pre-existing structures: Insights and regional implications from the Barmer Basin rift

Complex rift geometries resulting from inheritance of pre-existing structures: Insights and regional implications from the Barmer Basin rift

Geology and regional significance of the Sarnoo Hills, eastern rift margin of the Barmer Basin, NW India

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