Abstract
The palaeoposition of India after its breakup from Gondwana and its subsequent northward journey during the Mesozoic poses many tectonic riddles. A magnetostratigraphy pattern has been constructed for the Ammonoid rich Middle Jurassic Bathonian succession of Jumara Dome, Kachchh, western India. We present the first magnetostratigraphic results from the Ammonoid bearing exposed Bathonian sediments in Kachchh. The Jumara Dome comprised of mixed carbonate-siliciclastic succession is represented by the Jhurio and Patcham formations and siliciclastic-dominating Chari Formation in the Kachchh Mainland. The Jumara Dome sediments were deposited during sea-level fluctuating, and were interrupted by storms in the shallow marine environment. This study is based on collection of 60 oriented samples from 13 successive levels. Both thermal and AF demagnetization investigations were carried out to isolate the Characteristic Remanent Magnetization (ChRM) directions. Palaeolatitudes were computed using the ChRM directions. Magnetostratigraphic column is prepared and correlated with Geological Time Scale (GTS) of [1] [2], and this column readily matched with GTS at M41 to below and exhibits the dominance of normal polarity in Jumara.
Highlights
Several models based on geological and geophysical evidences for the tectonic evolution of the Indian plateHow to cite this paper: Mamilla, V., Pandey, B., Pathak, D.B., Guguloth, P. and Krishna, J. (2016) Magnetostratigraphy of the Middle Jurassic Sediments from Kachchh Basin, Western India
During the first phase of continental rifting Gondwana broke apart in to two equal parts, western Gondwana composed of Africa and south America and eastern Gondwana composed of India, East Antarctica, Madagascar, Australia, the Seychelles, and other microcontinental blocks, separated from Africa in the Mid-Jurassic [4] [5]
The Mesozoic sediments are exposed in the Kachchh Mainland, Patcham, Khadir, Bela, Wagad and Chorad Islands in the Great Runn of Kachchh
Summary
Several models based on geological and geophysical evidences for the tectonic evolution of the Indian plateHow to cite this paper: Mamilla, V., Pandey, B., Pathak, D.B., Guguloth, P. and Krishna, J. (2016) Magnetostratigraphy of the Middle Jurassic Sediments from Kachchh Basin, Western India. The basin is bordered by the subsurface Nagarparkar Massif in the north, RadhanpurBarmer Arch in the east and Kathiawar uplift to the south [7] In this pericratonic rift basin [8]-[10], Mesozoic sediments ranging in age from Bajocian to Albian lay unconformably on the Precambrian basement [11]. The Mesozoic sediments are exposed in the Kachchh Mainland, Patcham, Khadir, Bela, Wagad and Chorad Islands in the Great Runn of Kachchh. The Middle Jurassic Ammonoid bearing Bathonian sedimentary successions are beautifully exposed in Kachchh Mainland and Island Belts of the Kachchh basin (Figure 1). The fossiliferous Bathonian section is found the best developed at Jumara in the Kachchh Mainland (Figure 1) These sediments present their beautiful outcrops in Patcham Island (Sadhara Dome, Kala Dongar and Gora Dongar range) and other localities of the Kachchh Mainland (Jhura, Nara and Habo Domes). The sedimentary succession at Jumara has been litho- and bio-stratigraphically resolved and is expected to be potential exposure for integrated litho-biomagneto-stratigraphic studies during Bathonian interval (167.7 Ma to 164.4 Ma, GTS 2008) in India
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