Geology of Udaipur

History Of Udaipur

(both phosphates and non-phosphatic) are seen in different blocks of the Jhamarkotra deposit, as well as at Maton, Kanpur, Sisarma, Bargaon, Dakankotra, Kharbaria-Ka-Gurha, and Neemach Mata. At the northern abutment of the Fateh Sagar dam, stromatolites can be seen at the place where canal from Madar joins the lake; perhaps this is the nearest locality where these algal structures can be seen in Udaipur. Both the basal valcanoclastic sediments and carbonates constitute the Lower Aravalli Group in the type area.After the deposition of carbonates associated with rock phosphate and uraniferous black shale, the area was once again subjected to tectonic rejuvenation. The two faults which shaped the epicontinental sea once again became active. The source area was uplifted supplying more and more sediments to the epicontinental sea. As a result a thick sequence of conglomerate- greywacke-shale got deposited rapidly. Most of the Udaipur City area is occupied by this greywacke-phyllite sequence. The conglomerate with large angular to sub-rounded blocks and boulders of different composition and studded in phyllitic matrix can be seen at Bhupalpura, at several places in the city area and also in the Hiran Magri Sectors. Fascinating greywacke-phyllite rhythmites can be seen in a road cutting south of Paras Cinema and around the Pala Ganeshji temple near the Sajjan Niwas Garden. It would be interesting to note that th~ rapid influx of terrigenous sediments continued in the epicontinental sea till it was completely filled in and land conditions were evolved in its place. The greywacke-phyllite laminates forming the top part the sequence are best exposed at Pala Ganeshji. This sequence indicates how the supply of sediment from the source area gradually diminished and ultimately stopped. this conglomerate-greywacke- phyllite sequence of the Middle Aravalli Group is a classic example of a complete sedimentation cycle from formation of a basin to its complete filling up with the sediments. As a result, the epicontinental sea withdrew from the Udaipur valley and an Aravallian river occupied its place depositing an argillite-silty-arenite sequence with the lenticular bodies of polymictic conglomerate followed by a thick sand sequence at the base. This unit exhibits a variety of sedimentary structures as testimony of its fluvial origin. Variation in lithology from sand, silt to shale has made display of these structures rather conspicuous. The fluvial sequence occupies the heart of the Udaipur valley forming a small hill that extends from Machala Magara in the south to Pratap Smarak (Moti Magari) in the north through the city palace. At Pratap Smarak, it takes a sharp turn and extends up to Bada Hawala in the west of Fateh Sagar Lake through Nehru Park. Fascinating sedirhentary structures can easily be seen while strolling along the serpentine road along the eastern side of the Fateh Sagar Lake. Similar structures attract the attention of tourists visiting Manikya Lal Verma and Deen Dayal Upadhyay gardens on either sides of Doodh Talai, an eastern extension of the Pichola Lake. Though the epicontinental sea withdrew from the Udaipur valley but it continued further south around Zawar depositing carbonates with lead and zinc. Deposition of sand-shale sequence continued through out the Aravalli period along the western slope of the linear landmasses that separated the epicontinental sea of Udaipur valley from the main deep sea. The rocks of deep sea sequence forming drab hills with egg-basket topography crop out further west of an important watershed, that separates regional drainage to the Bay of Bengal from the one that goes to the Arabian sea. Aravalli rocks show a very low grade of metamorphism (green schist facies) except along their contact with underlying basement the Mewar Gneiss, where high grade metamorphism resulted in formation of garnet, sillimanite, andalusite, kyanite, and chloritoid. The Metamorphism in the younger argellite-silty-arenite fluvial sequence is of even low order and the rocks look almost unmetamorphosed. Younger intrusives occur in the form of mafic and ultramafic dykes. One such dole rite dyke crops out east of Nai village at its contact has metamorphosed a carbonate rock to sideritic marble-popularly known as "Panther Marble". This dole rite dyke can be seen at road bifurcation of Nai village on way to ]harol. All along the periphery of the Girwa valley pockets of fine-flaky-talcose white hydrous mica, commercially utilized as "pyrophyllite", are being economically exploited. These deposits at the contact of the Aravalli rocks with the basement represent pockets of paleosols confirming its unconformable character.

Present topography of the Udaipur valley and the amphitheater located in its heart has not been carved by the long time denudation and weathering alone but mainly by polyphase deformation that affected the Aravalli Supergroup of rocks. Two major and several minor folding episodes and a number of shear zones, both Precambrian and post-Precambrian, shaped the bedrock geology Machala Magara, Sajjangarh, and Pratap Smarak are good examples of superposed folding. Mesoscopic folds of different types can be seen at a number of places within the city. Greywacke-phyllite sequence displays not only folds but also different planer structures and their refraction fanning and curving is also well documented in this sequence, Neotectonic activity that brought disruptive changes in the land to the west of the Aravalli Mountain also left its signatures in this so-called stable shield. Reversal of drainage of Saraswati and Drishadwati river system caused migration of population from riverbanks to hilly terrain of the Aravalli, Archeological findings of Ahar / Banas civilization excavated at several places like Bedla, Bhuwana, Bichari, Dabok, Bhimal and Dhulkot (Ahar) have links with the ancient civilization ( 4000 BP) that flourished on the banks of Indus and Saraswati rivers. All the subsequent Neotecto:lic changes controlled the dehabilitation and rehabilitation in the Udaipur valley. Climatic changes causing long term draught and flood conditions are also reflected in three stages of the Ahar Civilization well preserved at Dhulkot near the new campus of the Mohan Lal Sukhadia University.

Explanation to the Geological Map of 
Area West of Udaipur
Lithounits and calculated attitude of structures 
from different sub area

1. Basement granite, granite gneiss and amphibolites

2. Green schist -amphibolite (altered basic volcanics) and conglomerate with green matrix and pyrophyllite at the base.

3. Conglomerate (with quartzitic/arkosic matrix)- banded hematite quartzite orthoquartzite (ferruginous at the base).

4. Quartzite -dolomite facies variation, dolomite with rock phosphate, sidertic marble and impure crystalline dolomite.

5. Carbonaceous phyllite -slate, phyllite -mica schist

6. Conglomerate (with phyllitic matrix), greywacke -phyllite -laminated greywacke - phyllite rhythmite.

7. Conglomerate (with quatzitic matrix) quartzite -silty arenite.

8. Jharol phyllite.