Manuscript Click here to view linked References Geological Site Characterization of Mandla region, Eastern 1 2 3 Deccan Volcanic Province, Central India 4 5 6 K.N.S.S.S. Srinivas*, P. Pavan Kishore and D.V. Subba Rao 7 8 CSIR - National Geophysical Research Institute, Uppal Road, Hyderabad – 500 007. 9 10 11 *Corresponding Author: K.N.S.S.S. Srinivas 12 Email: [email protected]* 13 14 15 16 Abstract 17 The detailed geological studies carried on basaltic sequences along Jabalpur-Niwas, 18 19 Jabalpur-Chutka and Jabalpur-Mandla traverses covering an area of about 12km*15km 20 21 area to characterize various basaltic lava flows and their behaviour on seismotectonics 22 23 and geodynamic setting of their formation in Mandla region of the Eastern Deccan 24 25 Volcanic Province (EDVP). The studies involve analysis of the satellite images for 26 27 identification of lineaments/faults and field geological studies consist of geological 28 controls such as ground check, thickness of fractures and orientation along the 29 30 acknowledged lineaments/faults. The results of present research, 65 lineaments/faults 31 32 mainly belong to two geometric groups, minor and major with dominantly in NW-SE, 33 34 NE-SW orientation and altered strata varying lithology (weathered to compact basalts) 35 36 recognized in the study area. Based on their extent, 57 lineaments have been classified 37 38 as minor (< 100km) trends in three different orientations i.e NNE-SSW, ESE-WNW and 39 ENE-WSW, whereas 8 lineaments as intermediate (300-100km) trends in NNE-SSW. 40 41 No major (>300km) lineaments are noticed in the study region. The field geological 42 43 investigations have facilitated the recognition of ten flows with different characteristic 44 45 features and a variety of volcanic structures such as columnar, vesicular, amygdaloidal, 46 47 inflated pahoehoe lava flows, red bole interflow horizons have been documented. 48 Basement rocks of these Deccan basalt lavas are represented by Tirodi Biotite gneisses, 49 50 quartzite, quartz-mica schists and crystalline limestone in the SE part of the study area 51 52 of Mandla region. The present study will help to evaluate localized site characterization 53 54 for urban planning and setting up of major civil structures. 55 56 57 58 Key words: Mandla region, geological studies, lineaments, satellite images, Eastern 59 60 Deccan Volcanic Province 61 62 63 64 65 1. Introduction: 1 2 The Deccan Volcanic Province is one of the Large Igneous Provinces (LIP) in 3 4 the world which has been studied since many decades for its stratigraphy, structure, 5 6 geochemistry, petrogenesis, geochronology and duration of the volcanism (Mukherjee 7 et al. 2017). It is the most extensive, with an area of >5,00,000 sq.km covering the states 8 9 of Gujarat, Maharashtra, Madhya Pradesh, Andhra Pradesh, Karnataka, Goa and Daman 10 11 and Diu. Deccan Basalts near the coast is 1500 m which decreases to 400 m in the 12 13 central region (Alexander 1979 and 1981, Kaila et al. 1979, 1981 a and b). Variation in 14 15 thickness is controlled by 1) Pre-Deccan topography, 2) N-S trending fault system, 16 17 which is more prominent in Western Ghat sections and 3) the differences in the depth to 18 Moho. More than 48 flows were recognized, which erupted in a very short time 19 20 (Rajarao et al. 1999; West 1981; Mishra et al. 2017). Deccan Continental Flood Basalt 21 22 Province (DCFBP) is related to the reunion hotspot and eruptions of this voluminous 23 24 lava took place within a short period of 0.5 to 2Ma (Naqvi 2005), close to the 25 26 Cretaceous-Tertiary boundary (Hooper 1999). The DCFBP has been studied at several 27 locations and its structure, thickness, ages, composition, and nature of intertrappean 28 29 beds have been approached by geological, geophysical and geochemical techniques. Out 30 31 of the ~5,00,000 sq.kms, the area making Western Ghats including the Mahabaleshwar 32 33 hills have provided enormous information (Cox 1980., Cox and Hawkesworth, 1984). 34 35 Deep Seismic Sounding (DSS) data indicated that the volcanic pile is about 100 m in 36 37 the NE and gradually increases up to 1000 m in the west (Kaila 1988). 38 39 40 The Eastern Deccan Volcanic Province is an elongated outlier that extends 344 41 42 Km E-W and 156 Km N-S covering an area of 29,351 sq.km around Jabalpur, Mandla, 43 44 Dindori, Amarkantak and Seoni areas (Kashyap et al. 2010). The Mandla Lobe forms a 45 46 900 m thick lava pile. The geological and tectonic framework of any continental region 47 48 can be considered as a reflection of its time-bound integrated geodynamic evolution. 49 Hence deciphering and understanding of their physical, thermo-tectonic, compositional 50 51 nature especially in those areas, which have thick overburden becomes a major 52 53 challenge. It is generally believed that shields are seismically stable but Jabalpur, Latur, 54 55 Bhuj, Koyna and other earthquakes in the stable continental crust have indicated some 56 57 subcrustal movement below the stable shields also (Gupta 1994 and Gupta et al. 1995). 58 59 Out of the several earthquakes, the Jabalpur earthquake of 1997 occurred at a depth of 60 35 km. Jabalpur is situated within the Central Indian Suture Zone (CISZ) and is 61 62 63 64 65 characterized by high surface heat flow of 70-100w/m2 (Ravi Shankar 1988; 1 2 Mahadevan 1994). 3 In view of the above mentioned intraplate seismicity, detailed geological field 4 5 studies using satellite images carried out in relatively less studied Mandla region of 6 7 Eastern Deccan Continental Flood Basalt Province (EDCFPB). It is also believed that 8 9 the basement below the thick cover of the continental flood basalt is highly resistive, but 10 11 not uniform and appears to be intersected by faults (Harinarayana et al. 2004). The 12 13 Western Ghat section in Western Deccan Volcanic Province (WDVP) is regarded as one 14 of the well studied lava sections of the DVP in terms of structure, composition and 15 16 dynamics (Subbarao and Hooper 1988; Kaila et al. 1987; Tiwari and Mishra 1999; 17 18 Tiwari et al. 2001; Ramesh et al. 1993; Naqvi 2005 and Ramakrishnan and 19 20 Vaidhyanadhan 2008). But, the Mandla region has not been studied the analysis of 21 22 satellite images for identification of lineaments/faults and field geological studies 23 24 consist of geological controls such as ground check, thickness of joints/fractures and 25 orientation along the acknowledged lineaments/faults. With an emphasis, geological 26 27 field studies were adopted on Jabalpur-Seoni (JS), Jabalpur-Mandla (JM) and Jabalpur- 28 29 Niwas (JN) traverses (Fig 2) and the results are discussed in the present paper. 30 31 32 33 2. Location of the study area: 34 35 The study area is located in Mandla, Seoni and Jabalpur districts of Eastern 36 Madhya Pradesh state and also forms a part of the Eastern Deccan Volcanic Province 37 38 (EDVP) wherein the well known Mandla region is situated in the NE part of the Deccan 39 40 Volcanic Province (DVP) (Fig 1). The study region is located within the coordinates of 41 42 22°30’N to 23°15’N and 79°45’E to 80°30’E. The detailed field geological studies 43 44 carried out along Jabalpur-Seoni (JS), Jabalpur-Mandla (JM) and Jabalpur-Niwas (JN) 45 46 (Fig 2). 47 48 49 3. Geological setting and Lithology of Mandla lobe: 50 51 The study area occupies mainly within the Mandla outlier in the Eastern Deccan 52 53 Volcanic Province (EDVP). EDVP is an elongated outlier that extends 344 Km E-W 54 55 and 156 Km N-S covering an area of 29,351 sq.km around Jabalpur, Mandla, Dindori, 56 57 Amarkantak and Seoni areas (Kashyap et al. 2010). The Mandla Lobe forms a 900 m 58 59 thick lava pile. The landscape is covered by flat-topped plateaus and ridges with small 60 61 62 63 64 65 mesas, mounds and buttes. The study of this outlier is significant because of its 1 2 occurrence within the Narmada-Tapti rift system (Hooper 1990). Physiographically, this 3 study region forms part of the Satpura hill range of Central India. The physiographic 4 5 features include plateaus in the northern part formed by basalt and east-west trending 6 7 hills in the southern part. Narmada river and its tributaries drain the northern and north- 8 9 western part of the study region. Geologically, the area forms the southern fringe of 10 11 Son-Narmada-Tapti (SONATA) lineament zone, the ENE-WSW trending major 12 13 tectonic zone within the Central Indian Shield, with evidences of tectonic activity from 14 Paleoproterozoic to the recent. ENE-WSW trending Central Indian Tectonic Zone 15 16 (CITZ) is located in the southern part. The study region is dominantly occupied by 17 18 Deccan Traps (Table- 1, Fig 3). More than 95% of the area is covered by these rock 19 20 types which unconformable overlie the Precambrian granite gneiss. Deccan trap flows 21 22 are seen to occur at different elevations in the area probably because of the uneven 23 24 nature of the basement as well as uneven thickness of the individual lava flow 25 (Keszthelyi et al. 1999). The Quaternary sediments lie unconformably over the eroded 26 27 surface of Deccan Trap lava flows. The field geological investigations carried out and 28 29 described in Table-2.