Geology of Maharashtra

GEOLOGY OF MAHARASHTRA                

                   The  State of Maharashtra encompasses on area of 307713 sq.km.  Out of which likely mineral bearing area is about 58465 sq.km. i.e. 19% of the total area of the State.   Divisionwise distribution of mineral bearing area is

1)         Nagpur            -          60%

2)         Amravati         -           10%

3)         Konkan           -           20%

4)         Aurangabad    -           5%

5)         Pune                -           3%

6)         Nasik               -           2%

 

GEOLOGY OF THE STATE

The entire area of the State forms a part of the “Peninsular Shield”, which is composed of rocks commencing from the most ancient rocks of diverse origin, which have undergone considerable metamorphism.   Over these ancient rocks of Precambrian era lie a few basins of Proterozoic era and of permocarboniferous periods which are covered by extensive sheets of horizontally bedded lava flows comprising the Deccan trap.   More than 80% area of the State is covered by these Deccan trap, which have concealed geologically older formations.  The most important economic minerals such as coal, iron ore, manganese ore, limestone, etc. are found in the geologically older formations.

 

STRUCTURE   : Structurally, the entire area of the state forms a part of the “Peninsular Shield” of India which represents a fairly stable block of earth crust that has remained unaffected by, mountain building movements, since the advent of the Palaeozoic era.   Some of the subsequent movements in the crust have been of the nature of normal and block faulting which have laid down certain portions bounded by tensional cracks of faults giving rise to basins in which sedimentary beds of the Gondwana age have been deposited.   Particularly in the Vidarbha region giving rise to the the important limestone as Penganga beds and coalfields of the Pench-Kanhan valley, the Umred – Bander field the Wardha valley and Vidarbha valley.  It is generally accepted that the Western coast has been formed as a result of the faulting.   Along this coast from Ratnagiri to Mumbai, and further north in Thane district there exists a series of hot springs arranged almost in linear fashion which suggests that they are situated on a line of fracture.   Further evidence regarding the formation of west coast by faulting is offered by the Western Ghats comprising Deccan trap lava flows, which are several hundred metres thick near the coast and which gradually thins out east wards.   Near Panvel, near the west coast the Deccan traps show westerly slopes indicating designated as Panvel flexure.

 

Association of Economic Minerals with Gological Formations and their Geographic Distributions in the State

An intimate knowledge of geological formations and their geographic distribution provides a very important clue not only to the occurrence of minerals, but also forms the basis on which all future search for economic minerals could be based.   From the genetidc and structural point of view, there is a definite relation between the geological formations or rock types in any region and the type of economic minerals that are associated.   Thus, the most important iron ore and manganese ore deposits of India occur closely associated with the formations of Precambrian era and the most important limestone and dolomite deposits are associated with the rocks of Penganga, Pakhal and Kaladgi groups.   Similarly, the most important coalfields are associated with the sedimentary rocks of the Gondwana sequence.   The important oil deposits of India are associated with rock formations of  the Tertiary period and so on.  It is, therefore, of prime importance to know intimately the nature of occurrence and distribution of different geological formations that occur in the various parts of the State in order to have a proper knowledge of the potentialities of mineral wealth and for guiding the search for future location of mineral deposits.

 

The stratigraphical sequence of the various rock formations that occur in Maharashtra State and the important minerals that are associated with each formation are shown in the Table given below :

TABLE

Time units (Period)	Type rock formation	Associated mineral
1	2	4
Recent, Sub-Recent and Pleistocene Miocene-Pliocene	Alluvium Laterite Soil Sand etc. Tertiary sediments lignite, shales	Kankar, Brick and pottery clay, sand illmenite,inferior grades of iron ore and manganese ore, ochres, bauxite lithomarge, etc. Clays, Lignite

Lower Eocene-upper cretaceous	Deccan trap with the intertrappeans and infratrappeans (Lametas, Bagh beds)	Building stone road meatal, inferior limestone, agate, jasper, opal, rock crystal, calcite, zeolites, gypsum etc.
Jurassic (Upper Gondwana)	Limestone, Chikiala and kota formation	Limestone
Triassic	Clays, Sandstones and Maleri formation	Sandstone and clays
Permian (Lower Gondwana)	Sandstone and shales Mangli beds Sandstone and Shales Kamthi formation.   Micaceous sandstone with clays.	Clays
	Motur formation (Sandstone and Shale).  Barakar formation (Sandstone Carbonaceous shale and coal)	Coal fire clays
Upper Carboniferous	Talchir formation	----
Pre-Cambrian	Limestone, Shales and Sandstones (prenganga beds).  Limestone and shales (Pakhal group).  Sandstones, limestone Conglomerates, quartzites and shales (Kaladgi Group).  Sausar Group	Limestone, Fluorite Limestone, Baryte Limestone, Clays, Glass sand, foundry sand Manganese ore, calcitic and dolomitic crystalline marble, quartz

	Dongargarth Group/Sakoli Group, Iron ore Group	Iron ore, Chromite, Tungsten ores, Copper ore, Zinc ore, Gold Manganese ore, Kyanite, Sillimanite, Corundum, Pyrophylite etc.
Precambrian (Older)	Older Schists and gneisses (unclassified crystallines)	Barytes, chromite, felspar, sillimanite, quartz, soapstone, antimony, corundum, copper, mica, etc.