Open Journal of Geology, 2012, 2, 80-90 http://dx.doi.org/10.4236/ojg.2012.22009 Published Online April 2012 (http://www.SciRP.org/journal/ojg) Facies Development and Depositional Environment of the Patherwa Formation (Semri Group), Son Valley, India Abul Hasnat Masood Ahmad 1 , Ghulam Mohammad Bhat 2 , Ruchi Agarwal 1 1 Department of Geology, Aligarh Muslim University, Aligarh, India 2 Postgraduate Department of Geology, Jammu University, Jammu, India Email: agrawal.geology@gmail.com Received September 29, 2011; revised December 1, 2011; accepted February 16, 2012 ABSTRACT The present study documents three facies associations recorded from the Patherwa Formation. These facies are related to tidally influenced fluvial channel (Facies association A), tidal channel (Facies association B) and tidal sand bar/tidal flat sandy facies (Facies association C). The spatio-temporal variation of these facies associations and palaeocurrent trends suggest tide dominated estuarine system. The estuaries were operational along a 60 km long NW-SE trending palaeo-shoreline. The Patherwa Formation grades up-section into facies packages of increasing tidal energy and termi- nate with the deposition within the upper flow regime estuarine settings. Keywords: Vindhyan Basin; Sedimentary Facies; Palaeocurrents; Estuary; Tidal Flats; Upper Flow Regime 1. Introduction The Vindhyan Supergroup represented by a thick pile of sediments belonging to the Semri, Kaimur, Rewa and Bhander Groups, is one of the largest Proterozoic sedi- mentary basins of India. It is spread over an estimated 100,000 km 2 area extending from Sasaram (Bihar) in the east to Chittorgarh (Rajasthan) in the west, see Figure 1. The Vindhyan basin is a peripheral foreland basin that developed in front of the arcurate fold belts of Aravalli, Delhi and Satpura with which it has a thrusted contact [1-3]. The Proterozoic Vindhyan Supergroup of India has at- tracted the attention of geologists since 1856 owing to the presence of diverse rock types [4]. These thick (4000 m) and unmetamorphosed sediments have been broadly divided into two lithostratigraphic units. The Lower Vindhyan or the Semri Group, and the Upper Vindhyan comprising of the Kaimur, Rewa and Bhander Groups each separated by conglomerate units [5]. The Semri Group is folded [6], whereas the Upper Vindhyans are known to be tectonically undisturbed. The Vindhyan Basin is bordered by the Aravalli-Delhi orogenic belt (2500 - 900 Ma) [7] in the west while the Satpura oro- genic belt (1600 - 850 Ma) [8] occurs in the south and east. The Bundelkhand Granite Massif (3.3 - 2.5 Ga) [9] occurring at the centre of the basin divides the basin into two sub-basins, i.e., the Son valley Vindhyans in the east and the Aravalli Vindhyans in the west. The sedimentary fill of Vindhyan Basin is commonly believed to be of Middle and Late Proterozoic age [10,11]. [12] classified Semri Group of Vindhyan Supergroup into eight Forma- tions, see Table 1. The Semri Group depicts a cyclic sedimentation of rudacceous/arenaceous, argillaceous and carbonate facies, see Table 1. At least, three major cy- cles of sedimentation, each culminating in a tectono- magmatic activity, have been identified [12] in the Semri Group. [13] interpreted the depositional environment of the Vindhyan Basin to include high gradient environment. [6] suggests that the braid plain erg-transition appears to be a common phenomenon of the Proterozoic Era and its record should abound the terrestrial sandstones of that age. The Vindhyan sediments were deposited in the en- vironments ranging from fluvial to deep marine condi- tions [6,14,15]. These rocks are deposited in an E-W elongated epeiric sea opening westward [16,17]. The studied Patherwa Formation forms the base of the Semri Formation in the Son Valley and has an angular uncon- formity/thrusted contact with the underlying Bundelk- hand Granitoid Complex. The formation is composed of gritty to pebbly sandstones, medium grained sandstones and siltstones; conglomerates with cobbles, pebbles and clasts of quartz, chert, yellow and red jasper embedded in sandy matrix. The upper contact with the Arangi Shale Formation is conformable. Rather limited facies and palaeocurrent investigations of the Patherwa Formation have been carries out; these include those of [12,13,17]. Well exposed sequences at Hardi, Obra, Kewta and Markundi were selected for the present work. The Lithostratigraphy of this succession Copyright © 2012 SciRes. OJG