StratigraphyHow and when different Stratigraphic Sequences were formed What happened to them subsequently What are the important rock types associated with them Framework of Indian Precambrian About two-thirds of the Indian Peninsula comprises Precambrian rocks . These rocks: sedimentary suites & Deccan plateau basalts. The Indo-Gangetic plain occurring between the Precambrian rocks of the Indian Peninsula and the highly deformed suites of the Himalaya conceals northward dipping Precambrian rocks. therefore.Precambrian rocks of the Himalaya are highly tectonised due to collision of the Indian Peninsula with the Asiatic mainland and are separated from the southern shield by a northward dipping boundary thrust plane. . difficult to establish. The continuity of Precambrians below the Indo-Gangetic alluvium is. The Archean of India corresponds to the first half of the Pre Cambrian era. The Dravidian covers the period from Cambrian to middle Carboniferous. (iii) the Dravidian and (iv) the Aryan (the youngest). Contains the first formed rocks of the earth.Archean System divided into 4 groups: (i) the Archean (the earliest). . (ii) the Purana. and the Purana to the second half of the Pre-Cambrian. while the Aryan from the Carboniferous to the Pleistocene . . chromium. Karnataka. thorium. mica and building materials like granites. quartzites and conglomerates. Chhattisgarh. central and northern Himalayas. Jharkhand.no marks of fossils.P. Minerals are gold. uranium. copper. slates. Meghalaya and Rajasthan. Schists. marbles. manganese ore. Madhya Pradesh. A. Gneisses and granites. quartzites and slates .Rajasthan.TN. Jharkhand. iron ore. (ii) The Dharwar System are the earliest formed sedimentary rocks with no fossils. viz. . Aravalli and Satpura. Eastern Ghat. Dharwar.based on orogenic trend. Two such fundamental crustal dislocation zones in the Indian Precambrian are the Godavari graben and the Mahanadi graben. (instead of tectono-stratigraphiccrust could be divided into geologically well defined geographical parts . Later.The Indian Peninsula is : monolithic continental shield constituted by crystalline rocks. The combined Eastern and Northeastern part of the Peninsula. north and northeast of the Mahanadi graben with northern boundary formed by the Quaternary landscape of the Indo-Gangetic Plains and the Brahmaputra valley . can be called the Southern part of the Peninsula.The portion of the Indian Peninsula lying south of the Pranhita-Godavari graben. Another important part lying between Mahanadi graben and the Godavari graben is the Central part of the Peninsula. The North and Northwestern part of the Peninsula lies to north of the tectonic zone between the rocks of the Vindhyan Supergroup and the Bundelkhand-BGCAravalli. . structural. geochemical characteristics and geochronology. Each one further sub-divided into provinces on the basis of distinct lithological. metamorphic. cratonic block etc. However. genetic terms like craton. are in used . mobile belt.The boundaries of the provinces are usually marked by shear/ fault zone or in some cases by a transition zone. 68 0 72 0 76 0 80 0 84 0 88 0 92 0 96 0 360 Pz-Mz Q GEOLOGICAL MAP OF INDIA Pt Pt 3 + ++ NQs Pt + + ++ + Pt 3 + PzP Pz-Mz 36 0 MzCz SCALE Km. Dras Volcanics( MzCzd) / Ladakh Granitoids ( MzCz) and equivalent. & equivalents in Himalaya. PgN Pt Pz-Mz + + ++ + + + + + ++ Pt 3 320 32 0 NQs ++ Pt Pt Pz-Mz Pt Pt Mz Pg Mz DELHI 280 Pg Ptmr Mzj ++ +++ ++ Pt + Ptd Pt + ++ + + + Ptgw Aptbgn Pt 280 Pt PtPz Ptm Pt sh NQs Pz-Mz ++ Ptml 240 N Mz + + + + + Pte + + + + + + + +++ + + Ptd Ptml + + Ptm Pg Ab Ptv KTtl Q Ptv Aptb Ptbj Ptv Pz-Mz-g Ptml Pz-Mz-g Ptc N Pta Mz + + + + + + + + + + + Pt + + + Mzr Q N 24 0 Ptv Ptv ++ Q Apt Pts Q Ptsa Ptn ++ + + + + + + + Ptar + + + + PzMz-g Ptz + ++ Ptk Ptsn + ++ + + + + + + + + + + ++ + + + + Ptkr + + + ++ + + + + + + + ++ Pti Ptch + + + Q Pts MzCzdt KOLKATA ++ Aptb + + + ++ + Ptsm + + + ++ Ao+ + + + + + + + + + Ag ++++ + Asg ++ Pt Aptbl Ptd Aptgr 20 0 MUMBAI MzCzdt ++ + 200 16 0 A R A B I A N S E A 120 + + + + + + + + ++ + + Ptka ++ + + + + + + + + + + + + + + ++ ++ ++ ++ + Pt Apteg + + + + Ptkr + + + + + + + + Aptd + + + + + + + + + ++ + + + + ++ + + + + + + + + Ptc Apteg + + + + + Aptsg + + + + Aptp N Mz Ptc Aptgr BAY OF BENGAL Pt 16 0 + + Aptn CHENNAI Mz Pg ANDAMAN ISLANDS KTtl 120 Aptp Mz + + + N LAKSHADWEEP Aptgr N NICOBAR ISLANDS N 8 0 I 72 0 N 76 0 D I A N 80 0 SRI LANKA O C 84 0 E A N 88 0 Pg 80 92 0 AGE SEDIMENTARY & METAMORPHIC ROCKS Quaternary: Undifferentiated Sediments Plio-Pleistocene: Dihing.basic volcanics( Pt) and Dalma( Ptd) / Erinpura Granite( Pte). Palaeogene .Mahakoshal Gps (Ptml) / Sonakhan (Ptsn) / Singhbhum (Pts) / Simlipal (Ptsm). Archaean. Proterozoic: Closepet granitoid ( Ptc) & equivalent granitoids of Peninsular India and Himalaya. Kurnool (Ptkr) & equivalents.Bijawar (Ptbj). (Ptch). (Pta). Indravati Gp. Siwalik Group (NQ s).Cambrian: Undifferentiated Proterozoic-Palaeozoic formations of Himalaya. Dupitila.03 Geological map of India . IGNEOUS ROCKS Cretaceous-Tertiary:Ophiolites of Indus (KT) & equivalents in Nagaland and Andaman-Nicobar Islands (KTtl).Shillong Gp. Mesozoic-Teritary:Deccan Trap( MzCz dt). Banded gneisses (Aptbgn) / undifferentiated Dharwar Sgp. (Ptmr). Marwar Sgp. Delhi Sgp. Upper Proterozoic.(Aptd).100 MzCzd KTt 0 100 200Km. (Ptd).(Ptsh) & equivalents.Gwalior (Ptgw).(Aptn). (Pti). Nagaland. and marine Tethyan sedimentary formations in Himalaya. Abujmar (Ptar). Nandgaon (Ptn) and equivalents.Lower Proterozoic: Granitoids of Assam-Meghalaya ( PtPz). Mesozoic: Undifferentiated marine Mesozoic formations. Archipelago Gp. Undifferentiated Gneissic Complex of Chhotanagpur terrain (Ptc) / Meghalaya (Ptm). (Ptc). Proterozoic:Gabbro&anorthosite.Neogene of Himalaya. Archaean:Singhbhum Granite ( Asg) / Berach Granite ( Ab) & equivalent granitoids.Mesozoic: Undifferentiated GondwanaSgp (PzMz g). Archaean-Proterozoic:Peninsular Gneiss(Aptp). Q NQ N PgN Pg Mz PzMz Pt3 AGE KTt PtPz + + + + + + + + + + + + + + + + + + ++ + + + + + + + + Fig. Kaladgi Sgp.Bonai Gp.. I. Sargur Gp. Neogene formations of Peninsular shield.(Aptsg) / Gorumahisani Gp. Tipam Gps. AGE SEDIMENTARY & METAMORPHIC ROCKS Aravalli Sgp. Khairagarh (Ptk). Surma. Sakoli. (Ptv). Karewa Group (NQ k). Vindhyan Sgp. Palaeozoic .Andaman. Garwal Gp. Chattisgarh Sgp. (Ptsa). Proterozoic . Archaean: Eastern Greenstone(Apt eg).(Aptb) & equivalents / Grarulites(Aptgr). Malani plutonic/volcanic Suite( Ptml) & Granitoids of Himalaya. (Ptka) & equvalents in Himalaya Sausar (Pts) / Cuddapah Sgp.Rajmahal Trap( Mzr).(Ag) / Older metamorphics (Ao). Palaeogene:Undifferentiated Palaeogene(Pg)formations of Peninsula.Nellore gp.Proterozoic: Bundelkhand Granite ( APtb) / Bonai Lava ( APtbl). . Only a small part of the Eastern Ghats occupies the northeastern part. ancient supracrustal rocks. greenstones. The Precambrian rocks of the southern part of the Indian Peninsula are dominantly granulites. high-grade gneisses with migmatites.Salient characteristics of Precambrian geology of India The region falls south of Central India Tectonic Zone and southwest of the Godavari rift. post-tectonic granites . Cuddapah. . Bhima. The Dharwar Province falls in north & the two are separated by Palghat-Kavery shear zone. Pakhal and Sullavai. Badami. The southern part of the Peninsula comprises two provinces They are (i) Dharwar Province and (ii)Southern Granulite Province. Kaladgi. Kurnool. The tectonometamorphic status of the older and younger schist belts and the gneisses is not very clear . The Province is divisible into western and eastern parts along a major shear zone west of the Closepet Granite.The Dharwar Province is essentially a granitegreenstone terrain characterized by a number of NNW-SSE trending belts of schistose rocks separated by granitic terrains. but relics of an earlier supracrustal sequence (Sargur Group. ?3400 Ma) have been recognized which predate the granitic gneisses.The supracrustal schistose rocks (metavolcanics) belong mostly to Dharwar Supergroup (3000-2600 Ma). their transformation into granulites and also their subsequent retrogression.5 Ga old NilgiriMadras belt as well as even 550 Ma old charnockites of Madurai and Trivandrum area.The Southern Granulite Province is made up chiefly of charnockites.0 and 2. this province includes 2. As a result. . mafic granulites and khondalites and is intersected by several shear zones. however. but gneisses and supracrustal rocks of amphibolite facies are also abundant. The province is. not solely composed of rocks of granulite facies. Radiometric dates obtained from this province vary between 3.0 Ga indicating the ages of the parent rocks. This part is made up dominantly of Archaean to Middle Proterozoic basement complexes and Late Proterozoic to Early Palaeozoic platformal cover rocks .This province is often focused in recent literatures in an attempt to reconstruct the East Gondwanaland by a possible Madagascar-India fit. and the Narmada-Son Lineament (North). the Mahanadi and Godavari rifts. The central part of the Peninsular Shield forms broadly a rectangular area bounded by the Eastern Ghats. The Bastar Province represents major part of the Central Peninsula and includes the rocks of Sukma. Bastar Province. Sakoli. Dongargarh and Sakoli belt . Baster.g. Vindhyan.The greater part of the area is occupied by granites and gneisses with overlying supracrustals of metasedimentary and metavolcanic rocks of Sausar. Satpura Province and Eastern Ghats Province. Bengpal. viz. In this ancient terrain.). The central part has been broadly divided into three provinces. Bailadila and other suites. Indravati. a number of Late Proterozoic basins were developed (e. Amgaon. Bengpal. Bailadila. Chhatisgarh. etc. . Bilaspur-RaigarhSurguja belt and Betul-Chindwara belt) trending ENE-WSW to the west of the Chhattisgarh basin . thus. Sausar belt.0 Ga old (Pb-Pb age). The Satpura Province represents a Proterozoic mobile belt (including Mahakoshal belt.Some of the granitoids in the Bastar Province are intrusive into the supracrustal rocks while a number of them appear to form the basement and. More recently generated date (U-Pb from single zircon crystals) from the basement (tonalite gneiss) of the Kotri belt indicates an age of 3562 ± 2 Ma. are older than the supracrustals. The oldest granitoid in the Bastar province is a felsic gneiss occurring in Sukma area which is 3.The rocks in the province are extensively deformed and metamorphosed during the Early to Middle Proterozoic. 0 Ga) bounded by the arcuate Singhbhum shear / thrust zone in the north and northwest and Sukinda thrust in the south. Chhotanagpur Province and Meghalaya Province.. This Archaean basement is overlain to the north by Early Proterozoic supracrustals (North Singhbhum Mobile Belt) trending roughly E-W. .This part is separated from the rest of the Indian Peninsula by the Mahanadi rift graben bounding it in the west and south. The Singhbhum North Orissa Province is characterized by an Archaean continental nucleus (> 3. Different provinces included in this segment are Singhbhum-North Orissa Province. subordinate mafic/ ultramafic schists and minor anorthosites. granulites. Rocks of the Chhotanagpur belt range in age (K/ Ar dates) from 1500 to 800 Ma. Striking characteristics of the Singhbhum-North Orissa Province include wide spread occurrences of Early Archaean tonalitetrondhjemite gneiss and greenstone belts with prominent Banded Iron Formation. .This belt of supracrustals is bounded by the Chhotanagpur Province. which occurs further towards north. The youngest Precambiran supracrustal sediments in the province occur in the Kolhan basin showing a synclinal structure. The Chhotanagpur Province represents a sea of composite granitoids with enclaves of metasedimentary rocks. The Meghalaya Province is bounded to the south by the Dawki lineament and its northern edge is covered by alluvium of the Brahmaputra River .The terrain has experienced a series of tectonothermal events spanning over more than a billion years. the supracrustals of the Shillong Group. have been subdivided into the Gneissic Complex. 1700 Ma and 1150 Ma with the intrusive porphyritic granite plutons yielding ages around 800 and 550 Ma. The Gneissic Complex has yielded two Proterozoic dates viz. non-porphyritic granitic rocks. . the Khasi Greenstone and porphyritic plutons.The Precambrian rocks of the Khasi Hills representing a part of the province. The province is a basement reactivated terrain with a Proterozoic tectonothermal history comparing well with the Chhotanagpur terrain. . BGC Province and Aravalli-Delhi Province. Provinces identified in this part are Bundelkhand Province. quartz & dykes of dolerite. The Bundelkhand Province is broadly a triangular segment composed of granite-granodiorite. quartzofeldspathic gneisses and enclaves of metasedimentary and metavolcanic rocks. these two segments are separated from each other by a mega thrust/ fault known as the Great Boundary Fault.This part is bounded to the south by the Son-Narmada Tapti megalineament. Geochronological data indicate that the rocks were cratonised mainly in the Late Archaean period. Though the western and northern India is treated together here. The contact between the BGC and the overlying supracrustal suites is a well defined unconformity. Part of the Bhilwara Supergroup appears to represent a continental rift . the period of deposition of overlying Aravalli-Delhi Supergroup of rocks. greenstones and low grade granites showing a wide variety of ages (3500 to 2000 Ma) that overlap.The BGC Province is composed of an assemblage (BGC/ Bhilwara Supergroup) of high grade gneisses and granulites. The Aravalli-Delhi province is composed of Proterozoic supracrustal sequences classified as the Aravalli Supergroup and the Delhi Supergroup. Late Proterozoic igneous and sedimentary rock assemblages grouped under Malani Igneous Suite and Marwar Supergroup respectively. The Malani and Marwar rocks are not deformed indicating that the episodes of the Precambrian magmatism/ sedimentation in this part of northwestern India are post- . basic and ultrabasic intrusives and acid extrustives of different ages also occur in the Province. In addition. occupy a wide area to the west of the Aravalli Mountains. a host of granitic. The Delhi basins opened in close proximity to the Aravalli province following the evolution of the Aravalli Supergroup. where thick piles of volcano-sedimentary rocks were deposited. Deposition of the Aravalli rocks took place in fault-troughs under eugeosynclinalmiogeosynclinal environment. The joints in between the blocks are mostly thrusts/ rifts. along with cover rocks of Proterozoic and Phanerozoic age and accumulated in intracratonic sags and rifts. exact nature of which is often uncertain. The present day configuration of the Peninsular India took place mainly during the Middle Proterozoic period. . Deposition of platformal sediments in the sags and rifts was followed by legation of the blocks and it continued from Middle Proterozoic to Early Palaeozoic. mobile belts.Tectonically the Indian Peninsular Shield is a composite mosaic of several Precambrian crustal blocks characterized by cratons. terrains of basement reactivation etc. MCT) showing an average WNWESE trend in Extra-peninsular India . Some of these dislocation surfaces in Indian subcontinent are i) Phulad lineament (suture zone) in north-western India. iii) Singhbhum Shear Zone showing a curvilinear trend in eastern India. iv) E-W trending PalghatKaveri shear system in south India and v) Mega thrusts (MBT. ii) E-W trending Central Indian Shear in central India. These belts are associated with certain major tectonic elements indicating major zones of dislocation.The Middle Proterozoic rocks constitute complexly folded mobile belts along the margins of the cratonic blocks. Darjeeling and Arunachal Pradesh and ii) Western Himalaya. The average trend of the belt in the Eastern Himalaya is E-W while that the western Himalayan is nearly NW-SE . The Precambrians of the Extra-peninsular region have been described under two subdivisions viz. rest of the belt. Show identical geological features. i) Eastern Himalaya.The Extra-peninsular region forms the northern border of the Indian subcontinent and is occupied by the Himalayan mountain range.Sikkim. iii) Great (central) Himalayas and iv) Tibetan (Tethyan) Himalayas. These are (from south to north) i) Sub-Himalayas (foothills belt). ii) Lesser (lower) Himalayas.The bulk of the Himalayan range is composed of Proterozoic rocks that have undergone thrusting and reactivation during Meso-Cenozoic orogenesis. The Himalayan ranges can be subdivided longitudinally into four regions. The Sub-Himalayas are made up dominantly of Tertiary and Quaternary sediments. which were derived from northern mountains and accumulated along the Main Boundary Thrust bordering the Sub-Himalayas on the north . The Lesser Himalayas consists largely of nappes that override autochthonous Precambrian sedimentary suites. Multiple deformation and metamorphism. The Tibetan Himalayas are made up of supracrustal assemblage belonging to controversial theories of onestage Tethys or two-stage Tethys evolution . In addition. migmatisation and granitic emplacement have made this belt a complex tectonic unit. it contains Cenozoic granites. thrust-nappe tectonics. The Great Himalayas override the Lesser Himalayan belt along the Main Central Thrust. It is made up dominantly of high grade Precambrian metamorphites overthrust by Phanerozoic rocks. the Indian shield was subducted below the overriding Tethyan suite and a sedimentary wedge contained below the two converging plates. the belt bears stamps of geological activities spanning over a period from Early Proterozoic to the present. According to the plate-tectonic model.Though a theory of continental collision is related to the evolution of the Himalayas. It is believed that the Himalayan mountain chain is a part of the global Meso-Cenozoic mobile belt extending from the Atlas-Alpine mountain belts in the west to the Indonesian arc in the east . magmatism etc. The drifting and legation of India with Eurasia was preceded by rifting of several continental blocks from the northern Indo-Australian margin of the erstwhile Gondwana supercontinent and these tectonic processes took place during a period ranging from Silurian to Cretaceous.It is also thought that the northerly advancing IndoAfrican plate has subducted below the Eurasian plate leaving behind trails of ophiolite sutures. during the Precambrian period . metamorphism. events of deformation. Based on major cycles of sedimentation. In spite of the hindrances in unraveling the history of geological evolution. It is. needless to mention that the present idea on the scenario is not a complete one since concepts are still evolving with incremental enrichment of knowledge . the present state of knowledge on the subject is at an advanced stage through accumulation of new objective data. revolutionary changes in the understanding of global geological processes and interpretation of earlier and newly generated data which provided a comprehensive picture of this fascinating area of Indian geology. however.