Microbial mat structures in profile: The Neoproterozoic Sonia Sandstone, Rajasthan, India

Samanta, Pradip; Mukhopadhyay, S.; Mondal, Anudeb; Sarkar, S.

doi:10.1016/j.jseaes.2010.10.008

Cited by 34 publications

(23 citation statements)

References 34 publications

(57 reference statements)

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“…The frequent amalgamation of coarse sandstones, inferred as storm units with or without erosion, also corroborates the near-coastal condition of deposition of these units (Bose et al, 2001. The rectangular to polygonal desiccation cracks in non-cohesive sandstone owe their origin to microbial mats (cf., Noffke et al, 2001;Sarkar et al, 2008Sarkar et al, , 2014Eriksson et al, 2010;Samanta et al, 2011Samanta et al, , 2015. The wrinkles on sandstone bed-tops may have originated by gentle shear by waves or through currents acting on cohesive mat layers (Sarkar et al, , 2014.…”

Section: Discussionmentioning

confidence: 99%

Forced regressive wedge in the Mesoproterozoic Koldaha Shale, Vindhyan basin, Son valley, central India

Samanta

Mukhopadhyay

Eriksson

2016

Marine and Petroleum Geology

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The present paper highlights the sequence development within the Mesoproterozoic Koldaha Shale Member of the Kheinjua Formation, Vindhyan Supergroup which records the occurrence of a forced regressive wedge and associated discontinuity surfaces at the base of the wedge. Nine lithofacies have been identified within the study area that are grouped into three lithofacies associations varying in depositional setting from outer shelf, through shorefaceforeshore-beach to continental braidplain. The outer shelf sediments are aggradational to slightly progradational representing highstand systems tract. The rapidly progradational, wedge-shaped shoreface to foreshore-beach succession occurs sharply or erosively above the outer shelf sediments and is bounded by a regressive surface of marine erosion (RSME) at the base and by a subaerial unconformity at the top. This, along with its downstepping trajectory, supports deposition of this sedimentary wedge during falling sea level. A laterally extensive soft sediment deformation zone occurs at the base of the wedge.The forced regressive wedge is incised by fluvial braidplain deposits that rest on an erosive surface representing a sequence boundary. The thin braidplain deposits are the product of aggradation during a subsequent early rise in relative sea level, and thus, they are inferred to represent a lowstand systems tract. The constituent architectural elements that characterize the braidplain deposits are downstream accretion elements and small channel elements. Further 1 landward, the base and top of the shoreface wedge merge to form an unconformity across deposits that rest directly on the outer shelf sediments. The identification of forced regressive wedges has significant economic importance in view of the potential occurrence of hydrocarbons within the Proterozoic formations.

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Section: Discussionmentioning

confidence: 99%

Forced regressive wedge in the Mesoproterozoic Koldaha Shale, Vindhyan basin, Son valley, central India

Samanta

Mukhopadhyay

Eriksson

2016

Marine and Petroleum Geology

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“…There are several field evidences such as the number of structures on the successive bedding planes (Figs. Different varieties of microbial mat features have been documented from the Sonia Sandstone (Sarkar et al, 2008(Sarkar et al, , 2014Samanta et al, 2011;Kumar and Ahmad, 2014). 10A, B), preferred orientation matching the palaeocurrent direction on the same bedding plane (Fig.…”

Section: Taphonomymentioning

confidence: 99%

Enigmatic Ediacaran megascopic bedding plane structures on the Sonia Sandstone, Jodhpur Group, Marwar Supergroup, India: seaweed or problematica?

Pandey

Шарма

2016

Geol. J.

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The present study discusses the origin and affinity of enigmatic Ediacaran bedding plane structures reported earlier from the Sonia Sandstone of the Marwar Supergroup (Ediacaran to Lower Cambrian). These forms are conspicuously large, non‐carbonaceous and three‐dimensionally preserved. Morphologically, these structures are not comparable with any known plant/animal fossil, trace fossil, microbially induced sedimentary structures (MISS) found in the Ediacaran assemblages or any other extant forms and are invariably associated with MISS. Past researches on these fossils did not resolve their affinity, form and function. The present forms have certain features akin to seaweed organization such as thallus, loop pattern within the thallus, variously positioned nodes/swellings, tapering at the end of thallus, branching pattern and rarely occurring holdfast‐like features. Systematic description, incorporating detailed morphological features, population size, their relationship with associated sediments and stratigraphic distribution, is based on the study of 54 specimens. Subtidal to intertidal models of depositional sedimentary environment, palaeoecology, biogenicity, affinity, taphonomic changes, association of these forms with MISS and other parameters are also discussed. A succession of plausible interpretations is offered; seaweed is the most likely interpretation. The Marwar Supergroup, thus, unravels some of the hitherto enigmatic forms of the Ediacaran Period (635–541 Ma). Copyright © 2016 John Wiley & Sons, Ltd.

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“…This sandstone is subdivided into two intervals, the lower subaerial interval and the upper coastal marine interval (Fig. 1b;Sarkar et al, 2005;Samanta, 2009;Samanta et al, 2011). This formation is thought to be of Neoproterozoic age (ca.…”

Section: Geological Settingmentioning

confidence: 99%

“…600 Ma) on the basis of radiometric dating of acid volcanic rocks (Rathore et al, 1996;1998) that unconformably underlies the formation (Paliwal, 1998;Malone et al, 2008;Sarkar et al, 2005;. The base of the coastal marine interval is marked by a transgressive lag and is unconformably overlain by the non-marine interval of the Girbhakar Sandstone Formation (Samanta, 2009;Samanta et al, 2011;Sarkar et al, 2012). The thickness of the coastal marine interval is about 60 m and it is composed of three facies ranging in inferred palaeogeography from deeper neritic to supralittoral (Fig.…”

Section: Geological Settingmentioning

confidence: 99%

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Neoproterozoic substrate condition vis-à-vis microbial mat structure and its implications: Sonia Sandstone, Rajasthan, India

Samanta

Mukhopadhyay

Sarkar

et al. 2015

Journal of Asian Earth Sciences

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The present study deals with the Neoproterozoic mat-infested substrate sculptured by inferred boiturbations, excellently preserved within the ca. 600 Ma Sonia Sandstone, northwest India. The bioturbations are horizontal, being preserved on the bed-surfaces and have been classified into linear grooves and discoidal structures. The linear grooves are of two types, one group represents a straight to meandering pattern with raised sand ridges on either side, while the other group represents a mostly meandering pattern with changing width along the length, without raised ridges. Both types of grooves resemble trails of advanced organisms. The discoidal structures have five internal lobes emerging from the centre and merging with the outer ring and may represent body impressions of an organism; alternatively may represent variants of Ediacara or other soft bodied organisms. The interaction of the substrate with these possible bioturbators has great significance in establishing the evolutionary history of the substrate and resulting bioturbations during the Proterozoic. Microbial mats possibly provided oxygen and nutrients to he organisms and played an important role in their preservation. The study also tries to extrapolate the life style of these trace-makers. All these traces may raise speculation about the onset-time of some higher order organisms.

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Microbial mat structures in profile: The Neoproterozoic Sonia Sandstone, Rajasthan, India

Cited by 34 publications

References 34 publications

Forced regressive wedge in the Mesoproterozoic Koldaha Shale, Vindhyan basin, Son valley, central India

Forced regressive wedge in the Mesoproterozoic Koldaha Shale, Vindhyan basin, Son valley, central India

Enigmatic Ediacaran megascopic bedding plane structures on the Sonia Sandstone, Jodhpur Group, Marwar Supergroup, India: seaweed or problematica?

Neoproterozoic substrate condition vis-à-vis microbial mat structure and its implications: Sonia Sandstone, Rajasthan, India

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