Kutch

Kutch

Kutch basin has the well developed Jurassic age formations and considered as stratotype area of Jurassic age. The basin is deformed and have rift valleys. Evolution of basin is given below.

Evolution

• In the late Triassic period when Gondwana was break up, the NW part of India subjected to rifting.

• As a result, a series of horst and grabens was formed.

• Rifting led to depression and formation of E-W rift valleys.

• A major marine transgression event was occurred in mid Jurassic. Patcham formation was first deposited and overlain by Chari formation.

• Marine regression events then occurred in late Jurassic. Katrol and Umia formations were deposited.

• Deccan volcanism activities in late cretaceous overlain these sediments. 

Cross section of Kutch area

Jurassic of Kutch

• Rocks are folded into three parallel anticlinal ridges running E-W.

• Lower part show marine transgression phase while upper part shows marine regression phase.

• Lower parts are rich in carbonates while upper has siliceous rocks.

• Rocks are intruded with dykes and sills.

• It contains abundant fossils of Ammonites and Pelecypods.

Stratigraphy

Jurassic of Kutch area starts with Patcham formation. It has abundant Macrocephalus ammonite fossils. Limestone is dominant.

Patcham formation is overlain by Chari formation. Ammonite fossils are common. Dhosa oolites are 'golden' coloured oolitic limestone present in this formation.

From Katrol formation, siliceous rocks are dominant lithology. It has sandstone and shales.

Umia formation is rich in ammonite fossils and Trigonia (pelecypoda) fossils. The upper part of Umia formation contains Upper Gondwana flora fossils such as Ptilophyllum, Williamsonia etc.

Cretaceous formation (Bhuj)

Bhuj formation is of lower cretaceous age. The dominant lithology is bioturbated sandstone. They represents deltaic facies.

Upper cretaceous (Deccan volacnics)

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Cenozoic stratigraphy

Madh series marks the beginning of cenozoic strati in mainland. It is consisted for volcanic products plus argillaceous rocks. 

Lakhpat formation is important as it has lignite coal seams.