Cambrian trace fossils of the Cruziana ichnofacies from the Bikaner-Nagaur Basin,north western Indian Craton |
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| Institution: | 1. DST-Birbal Sahni Institute of Palaeosciences, 53-University Road, Lucknow 226 007, India;2. CSIR-Central Institute of Mining and Fuel Research, Barwa Road, Dhanbad 826 015, India;3. Academy of Scientific and Innovative Research, Ghaziabad 201 002, India;4. CSIR-National Institute of Oceanography, Dona Paula, Goa-403 004, India;5. Faculty of Sciences, Department of Geology, Campus Universitaire El-Manar, 2092 Tunis, Tunisia;6. Department of Earth Sciences, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India;7. Southern Regional Centre, Zoological Survey of India, Chennai 600 028, India |
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| Abstract: | The Marwar Supergroup of the Bikaner-Nagaur Basin is composed of sediments deposited from the late Neoproterozoic (Ediacaran) to Upper Cambrian. The Nagaur Sandstone Formation of the Nagaur Group (uppermost division of the Marwar Supergroup) preserves trace fossils significant for establishing Early Cambrian biostratigraphic zones and depositional facies. Fifteen ichnospecies (and eight ichnogenera) identified in the Nagaur Sandstone Formation include “Treptichnus” pedum, Cruziana cf. tenella, Cruziana isp., Diplichnites ispp. A, B, and C, Gyrophyllites isp., Lockeia isp., Merostomichnites isp., Monomorphichnus gregarius isp. nov., Monomorphichnus isp., Planolites isp., Psammichnites isp., Rusophycus bikanerus isp. nov., Rusophycus cf. carbonarius, Rusophycus isp. and radial trace fossils.These trace fossils belong to ethological categories pascichnia, repichnia, cubichnia, and fodinichnia and represent arthropod and worm-like burrowing biota. The assemblage and a regional comparison with contemporaneous trace fossils in the eastern Gondwanan realm suggest that the sequence in the study area belongs to the Cruziana tenella Ichnozone and to Stage 2 (upper part of Terreneuvian), however the Middle Cambrian is not excluded. The trace fossil assemblage belongs to the archetypal Cruziana ichnofacies. Cross bedded sandstone, mud cracks and rainprints in the ichniferous strata of the Nagaur Sandstone Formation indicate deposition in an intertidal sand flat with channels that was exposed episodically. |
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| Keywords: | Ichnology Shallow marine New Ichnotaxa Marwar Supergroup Rajasthan India |
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