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Sea level oscillations, climate change and landform evolution in the western coastal lowlands of Trivandrum block in Peninsular India

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Title Sea level oscillations, climate change and landform evolution in the western coastal lowlands of Trivandrum block in Peninsular India
 
Creator Mohan, S. Vishnu
Padmalal, D.
Maya, K.
Baburaj, B.
 
Subject Southwest coast of India
Holocene sea level changes
Sediment texture
Coastal evolution
 
Description 1145-1151
The
coastal areas of Kerala falling within the Trivandrum block, in the southern
side of the Achankovil Shear Zone (ASZ) of the Peninsular India, host a series
of coast perpendicular estuarine basins. These estuarine basins entrenched over
the Neogene sediments enfold a nearly complete record of Holocene
transgressive-regressive events. Borehole cores retrieved from the fluvial end
of these basins show a coarsening upward sequence with sand dominant sediments
at the top and clay dominant sediments at the bottom. The high terrestrial
inputs resulted from torrential rains in river catchments coupled with the sea
level rise during Early – Middle Holocene was instrumental in the development
of bay head deltas in the fluvial end and flood tide deltas/islands in the
marine end of these estuaries. The faster sea-ward growth than lateral spread
of these deltas was responsible for the cut-off of some of the prominent arms
of the pre-Holocene estuaries into separate freshwater bodies. The Sasthamkotta
kayal, Chelupola and Chittumala chira in the Ashtamudi basin, Kotta kayal and Pola chira in the Paravur basin and Poovankal wetland in the Nadayara
basin were evolved by this way. The Pallikkal river debouching into the
Kayamkulam lagoon also responded significantly to the Early Holocene climate
change and sea level oscillations. The river once debouched into the Kayamkulam
estuary at its middle presumably through the Krishnapuram Ar, was later took a southerly course linking the Late Pleistocene
(confirmed from C14 age of sediments) wetland bodies like Chunakkara
Punja, Komallur Punja, Vatta kayal and
Valummel Punja, and finally debouched
into the southern arm of the estuary near Vatta kayal. Heavy rainfall and beach barrier build up under the rising spells
of the sea in the Early – Middle Holocene was responsible for the wetland
capturing and diversion of river flow. The Karunagapalli borehole core gave an
age of 7270±250 yrs BP for an organic rich sediment sample at a depth of 6.9 m.
The Holocene sequence here is 9m thick and rests uncomfortably over the Neogene
sediments. This clearly indicates that the river received the present channel
configuration only in the second half of Early Holocene.
 
Date 2016-06-26T19:38:07Z
2016-06-26T19:38:07Z
2014-07
 
Type Article
 
Identifier 0975-1033 (Online); 0379-5136 (Print)
http://hdl.handle.net/123456789/34420
 
Language en_US
 
Rights CC Attribution-Noncommercial-No Derivative Works 2.5 India
 
Publisher NISCAIR-CSIR, India
 
Source IJMS Vol.43(7) [July 2014]