Page 328 - AWSAR 2.0

304 || AWSAR Awarded Popular Science Stories - 2019
encompasses a large number of cratons and basins of the Precambrian era that marked the beginning of the geological history of mother earth. Plate tectonic history of that era, which involves formation and breaking
up of the supercontinents are yet to be depicted undeniably.
In this regard, fractures
filled up with veins hosted by
the oldest rocks of the cratons
can provide a deep insight
about the stress conditions
that prevailed, transformed
and amended the Precambrian
tectonics. The fluids that once
filled up the fractures of the
Precambrian rocks are either
the end products of magmatic
differentiation or they are
the post-metamorphic fluids,
geochemical analysis of which
can reveal the bulk chemical
composition of the Archaean
lithosphere. Fractures and
faults filled up with magmatic veins are often reactivated when the fluid pressure (Pf) exceeds the normal stresses (σn) acting upon the fracture walls. This is a common phenomenon especially if the fractures are deep seated and interconnected to an underlying magma chamber that remains dormant and reactivates from time to time, leading to massive eruptions
magnified by tremors of high magnitude. This could be life threatening, especially if these vulnerable fractures are not monitored at frequent intervals leading to irreparable losses.
Statistical records suggest that magnitudes of such tremors recorded worldwide are often higher than Mw > 5-6, incurring yearly losses up to 365 million US dollars. Our country has been fortunate enough to escape these challenges, but for countries like Japan, this turns out to be the worst problem to deal with. Now the question lies how to deal with this problem? Fracture susceptibility (Sf) and tendency analysis could be the most effective answers to these problems. Slip tendency (Ts) and dilation tendency (Td) analysis helps to monitor the building up of shear/tensional stresses on fracture planes,
thereby predicting its propensity to reactivate. Simultaneously, fracture susceptibility provides the range for fluid pressure variation, sensitive to fracture reactivation. Thus, analyzing these parameters can help us to increase awareness, and save both lives and government aided funds to restore massive damages, and utilize them more efficiently.
Understanding how earth evolved through geological time and how our continents drifted and reassembled to attain the present configuration requires close observation of the small scale structures preserved within the rocks that form it. Geologists will continue to ensemble the remnants and reframe the past, until and unless we are blessed with a time machine.