New evidence confirms pre-continental sediments in Kutch and Cambay

Nagarjuna Danda at Field Camp
Nagarjuna Danda at Field Camp

Vasco-da-Gama,
February 24: Researchers have found presence of thick sediment layers dating
back to pre-continental era in the Cambay and Kutch basins of Gujarat.

Scientists Used electromagnetic geophysical methods

Using electromagnetic geophysical methods, scientists from Allahabad
centre of the Indian Institute of Geomagnetism found presence
of pre and post continental sediment layers in the region.

Researchers measured the earth’s natural electric and
magnetic variations and observed two high conductive and one high resistive layer.
The high resistive layer shows volcanic eruptions known as Deccan Traps, is about
0.5 to 1.5 kilometer thick. The top conductive layer is about 2 to 6 kilometers
thick Cenozoic sediment, while bottom layer is the pre-continental Mesozoic
sediment. This layer varies from site to site.

Scientist
carried out the magnetotelluric surveys along
four east-west corridors in the two basins passing through major
geographical locations at Sanchore, Tharad, Diyodar, Patan and Mehsana. The earth’s
electric and magnetic field variations were measured at 68 points to understand
the basement configuration and sediment thickness.

The thickness of pre-continental sediment could not be measured but these
are very thick at Mehsana site and thin at other sites, researchers said. The basement
of Cambay and Kutch basins
is approximately 5 to 7.7 kilometers deep.

“The deep high
conductive zone observed near Mehsana supports the evidence of thick
pre-continental sediments as suggested by deep seismic and other studies. Thick
Cenozoic and Mesozoic sediments play a role in tectonics and generation of
intraplate earthquakes in these basins,” explained Dr. C K Rao, leader of research team, while speaking to India Science
Wire
.

The Mesozoic
and Cenozoic sediments are records of evolutionary history of continents. The
present continents evolved from one
supercontinent Pangea during the Mesozoic era. It broke up into two parts – Gondwana
and Eurasia. These two parts further broke up into continents and started
drifting. The Cambay and Kutch rift basins record the earth’s evolutionary
history as they evolved in the Mesozoic time, underwent changes with basaltic
lava eruptions and Indo-Eurasian continental plate collision which formed the Himalaya.

The detailed
study of pre-continental sediments will be helpful in better understanding of
tectonics, earthquakes, evolution and drifting process of the continents. The
Cambay rift basin is also one of the major hydrocarbon producing rift basins in
India. The hydrocarbons from this basin are mainly explored from the thick
Cenozoic sediments.

This study
was carried out under the Ministry of Earth Sciences funded project and results
have been recently published in journal Current
Science
. The research team included Nagarjuna
Danda (DST Fellow) and Dr C.K. Rao.

(Dr. Ravi
Mishra, India Science Wire)

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