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Indian Journal of Geo-Marine Sciences (IJMS) >
IJMS Vol.40 [2011] >
IJMS Vol.40(3) [June 2011] >
| Title: | Subsurface reflections of prograded paleoscarps in Avis Island, North Andaman, India |
| Authors: | Vijaya Lakshmi, C.S.
Trivedi, Deshraj
Srinivasan, P.
Murthy, S.G.N.
Nair, Rajesh R |
| Keywords: | Ground Penetrating Radar
Heavy minerals
Magnetic susceptibility
Paleoscarps
Avis Island
Extreme wave events |
| Issue Date: | Jun-2011 |
| Publisher: | NISCAIR-CSIR, India |
| Abstract: | Prominent
subsurface reflections from two GPR transect marked four lithological anomalies
below Avis Island coral reefs. These scarps dip 5-10° towards sea and they consist
of sands with more than 30-40% heavy mineral concentrations that produce
distinct subsurface reflections that make possible to locate the buried
erosional scarps. Heavy minerals are considered as the indicators of erosion as
well as a proxy for sediment transport of extreme wave events. Heavy minerals
including magnetite have higher magnetic susceptibility values: L1a:°644.6;°L1b:°556.8,
L2a: 584.2 and L2b: 612×10-5°SI units to
the background magnetic susceptibility of 5-10×10-5°SI units for
quartz-rich sands suggest severe reworking process during an extreme
wave event. The two profiles (L1 and L2) with four paleoscarps: L1a at a
distance of 10 m from the shore, L2a approximately 15 m from the shore, L2b
around 30 m from the shore and L1b nearly 35 m from the shore and the
corresponding age of the dated coral above the paleoscarps increases towards
land exhibiting progradation sequence. These subsurface reflections of paleoscarps
were found at a depth of 1–1.5 m below the ground surface beneath the reported age of coral reefs suggesting that
these coral reefs and the paleoscarps are found due to the same event. |
| Page(s): | 331-337 |
| CC License: |  CC Attribution-Noncommercial-No Derivative Works 2.5 India |
| ISSN: | 0975-1033 (Online); 0379-5136 (Print) |
| Source: | IJMS Vol.40(3) [June 2011]
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