Early Cambrian Ichnofossils from the Mussoorie Syncline and revision of Trace Fossil Biozonation of the Lesser Himalaya, India

A new locality bearing ichnofossils of the Cruziana Assemblage Zone-Ⅲ from the Mussoorie syncline,Lesser Himalaya,is located in rocks of Member-B of the Dhaulagiri Formation,Tal Group,exposed along the Maldewta-Chhimoli fresh road cut section.The site yielded ichnofossils Bergaueria perata,Cochlichnus anguineus,？Diplocraterion isp.,Dimorphichnus obliquus,diplichnitiform Cruziana bonariensis,Diplichnites gouldi,Glockeria isp.,Helminthopsis isp.,Monomorphichnus lineatus,Phycodes palmatum,Palaeophycus striatus,Planolites beverleyensis,Planolites montanus,Treptichnus cf.T.pedum,scratch marks and an undetermined worm impression.An Early Cambrian age （Cambrian Series 2） is assigned to the ichnofossil-bearing strata based on the stratigraphic position between the Drepanuroides and Palaeoolenus trilobite zones.A revised Cambrian ichnofossil zonation is presented for the Tal Group of the Mussoorie syncline.Together with their occurrence on rippled surfaces,and the lateral displacement of some trackways （due to current action）,a sub-aqueous shallow-marine depositional setting is proposed for the rocks of Member-B.

Ichnofossils from the Miocene Middle Bhuban Formation, Mizoram, Northeast India and their Paleoenvironmental Significance

An ichnofossil assemblage is preserved in sediments of the Middle Bhuban Formation, Surma Group, of Miocene age from the Durtlang and Chanmari sections, Aizawl district, Mizoram, northeastern India. The studied sections comprise a thick, bioturbated and thinly bedded sandstone-silty shale facies. The preserved ichnofossils show high density and low diversity with the assemblage represented by feeding and resting traces, i.e., Psilonichnus upsilon Frey et al., 1984, Ophiomorpha isp., Teichichnus spiralis Mikulas. 1990, Skolithos isp., Palaeophycus isp., and other horizontal burrows. Sedimentary structures associated with these traces are mainly cross bedding, flaser bedding and slump structures. Considering the distribution of the Psilonichnus ichnogenus across an integrated ichnological-sedimentological framework, the stratigraphic interval of the Middle Bhuban Formation, in which they occur, are interpreted to have been deposited under a shallow, marginal-marine channel complex dominated by tidal channels developed in quiet, brackish-water portions of a delta plain.

Crustal deformation measurements by global positioning system(GPS)along NSL,western India

The Narmada Son Lineament(NSL)is a major palaeo-rift system and seismically active intra-plate region.In this paper,we processed and analyzed the GPS data from 2009 to 2016 to study the geodynamic characteristics of NSL.The velocities derived from GPS were used to calculate the associated deformation and crustal strain,while the slip deficit was estimated using the horizontal motion of GPS sites.The investigation reveals that the maximum deformation of western NSL is 1.6 mm per year,and the upper bound of the seismic moment(M;)is 2.0×10;dyn/cm,corresponding to an earthquake of about 6.0 magnitude.The study highlights the significance of Aravalli and Satpura mobile belts.The estimated strain of 0.03μstrain/yr is low but comparable to the stable continental region,and a close association of factors(the fragility,crustal conductors,and compressive tectonics)is considered responsible for seismogenic activities in western NSL.