EVOLUTION OF INDIA

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EVOLUTION OF INDIA

The Indian craton was once part of the Supercontinent of Pangaea. At that time, it was attached to Madagascar and southern Africa on the south west coast, and Australia along the east coast.

During the Jurassic Period, rifting caused Pangaea to break apart into two supercontinents namely, Gondwana (to the south) and Laurasia (to the north).

The Indian craton remained attached to Gondwana, until the Supercontinent began to rift apart about in the early Cretaceous.

The Indian Plate then drifted northward towards the Eurasian Plate. This orogeny, which is continuing today, is related to closure of the Tethys Ocean. The closure of this ocean, which created the Alps in Europe, and the Caucasus, range in western Asia, created Himalaya Mountains and the Tibetan Plateau in South Asia.

The current organic event is causing parts of the Asian continent to deform westward and eastward on either side of the orogeny.

Concurrently with this collision, the Indian Plate sutured on to the adjacent Australian Plate, forming a new larger plate, the Indo- Australian Plate.

Evolution of India

a) The cooling and solidification of the upper crust of the earth surface marked the earliest phase of tectonic evolution in the Archaean era (prior to 2.5 billion years) which is represented by the exposure of gneisses and granites especially on the Peninsula.  These form the core of the Indian craton.

b) The Aravalli Range is the remnant of an early Proterozoic orogeny called the Aravalli-Delhi orogeny that joined the two older segments that make up the Indian craton.

c) The erosion of the mountains and further deformation of the sediments of theDharwarian group marks the second phase. The volcanic activities and intrusions, associated with this second phase are recorded in composition of these sediments.

d) Early to Late Proterozoic calcareous and arenaceous deposits, which correspond to humid and semi-arid climatic regimes, were, deposited the Cuddapah and Vindhyan basins. These basins, which border or lie within the existing crystalline basement, were uplifted during the Cambrian (500 Ma).

e) The Vindhyans are believed to have been deposited between around 1700 and 650 Ma. Early Palaeozoic rocks are found in the Himalayas and consist of southerly-derived sediments eroded from the crystalline craton and deposited on the Indian platform.

f) In the Late Paleozoic, Permo-Carboniferous glaciations left extensive glacio-fluvial deposits across central India, in new basins created by sag/normal faulting.  These tillites and glacially derived sediments are designated the Gondwana series.

The sediments are overlain by rocks resulting from a Permian marine transgression (270 Ma).

The late Paleozoic coincided with the deformation and drift of the Gondwana super-continent.

To this drift, the uplift of the Vindhyan sediments and the deposition of northern peripheral sediments in the Himalayan Sea can be attributed.

During the Jurassic, as Pangaea began to rift apart, large grabens formed in central India filling with Upper Jurassic and Lower Cretaceous sandstones and conglomerates.

By the Late Cretaceous India had separated from Australia and Africa and was moving northward towards Asia. At this time, prior to the Deccan eruptions, uplift in southern India resulted in sedimentation in the adjacent nascent Indian Ocean.

Exposures of these rocks occur along the south Indian coast at Pondicherry and in Tamil Nadu.

At the close of the Mesozoic era, one of the greatest volcanic eruptions in earth's history occurred, the Deccan lava flows. Covering more than 500,000 square kilometers area, these mark the final break from Gondwana. In the early Tertiary, the first phase of the Himalayan orogeny, the Karakoram phase occurred. The Himalayan orogeny has continued to the present day.