Nisha,N R; Singh,A D(Department of Marine Geology and Geophysics,Faculty of Marine Sciences, 2002)
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Abstract:
In the present investigation, an attempt is made to study late Quaternary foraminiferal and pteropod records of the shelf of northern Kerala and to evaluate their potentiality in paleocenographic and paleoclimatic reconstruction. The study gives details of sediment cores, general characteristics of foraminifera and pteropod species recorded from the examined samples and their systematic classification, spatial distribution of Recent foraminifera and pteropods and their response to varying bathymetry, nature of substrate, organic matter content in sediment and hydrography across the shelf. An attempt is also made to establish an integrated chronostratigraphy for the examined core sections. An effort is also made to identify microfaunal criteria useful in biostratigraphic division in shallow marine core sections. An attempt is made to infer various factors responsible for the change in microfaunal assemblage. Reconstruction of sea level changes during the last 36,000 years was attempted based on the pteropod record. The study reveals a bathymetric control on benthic/planktic (BF/PF) foraminiferal and pteropods/planktic foraminiferal (Pt/PF) abundance ratio. Bathymetric distribution pattern of BF/PF ratio is opposite to the (Pt/PF) ratio with decreasing trend of former from the shore across the shelf. Quantitative benthic foraminiferal record in the surficial sediments reveals a positive correlation between the diversity and bathymetry. R-mode cluster analysis performed on 30n significant Recent benthic foraminiferal, determines three major assemblage.
Jeena, N S; Dr.Gopalakrishnan, A(Cochin University of Science And Technology, May 23, 2013)
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Abstract:
The management of exploited species requires the identification of
demographically isolated populations that can be considered as independent
management units (MUs), failuring in which can lead to over -fishing and
depletion of less productive stocks. By characterizing the distribution of genetic
variation, population sub structuring can be detected and the degree of
connectivity among populations can be estimated. The genetic variation can be
observed using identified molecular markers of both nuclear and mitochondrial
origin. Hence, the present work was undertaken to study the genetic diversity
and population/stock structure in P. homarus homarus and T. unimaculatus
from different landing centres along the Indian coast using nuclear (RAPD) and
mitochondrial DNA marker tools which will help towards developing
management strategies for management and conservation of these declining
resources.To make consistent conservation and fisheries management decisions,
accurate species identifications are needed. It is also suggested that it is not
always desirable to rely on a single sequence for taxonomic identification.
Thus, the feasibility of using partial sequences of additional mitochondrial
genes like 16SrRNA, 12SrRNA and nuclear 18SrRNA has also been explored
in our study. Phylogenies provide a sound foundation for establishing
taxonomy. The present work also attempts to reconstruct the phylogeny of
eleven species of commercially important lobsters from the Indian EEZ using
molecular markers
Description:
National Bureau of
Fish Genetic Resources (NBFGR) Cochin Unit, Central Marine Fisheries Research
Institute, Cochin
The thesis deals with the results of the study of the population characteristics of the marine penaeid prawn, Penaeus monodon from South India. The present findings on the morphometric and biochemical genetic structure support the hypothesis that the populations of P.monodon of South India have homogeneous stock structure. To the contrary, the significantly different random amplified polymorphic DNA (RAPD) profiles in samples of Kochi and Chennai support the hypothesis that east and west cost populations of P.monodon are separate stocks.
Manju, Nair P; Dr. Sujatha, C.H(Cochin University of Science & Technology, June , 2014)
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Abstract:
Geochemical composition is a set of data for predicting the climatic condition existing in an ecosystem. Both the surficial and core sediment geochemistry are helpful in monitoring, assessing and evaluating the marine environment. The aim of the research work is to assess the relationship between the biogeochemical constituents in the Cochin Estuarine System (CES), their modifications after a long period of anoxia and also to identify the various processes which control the sediment composition in this region, through a multivariate statistical approach. Therefore the study of present core sediment geochemistry has a critical role in unraveling the benchmark of their characterization. Sediment cores from four prominent zones of CES were examined for various biogeochemical aspects. The results have served as rejuvenating records for the prediction of core sediment status prevailing in the CES
Reji,Srinivas; Sajan,K(Department of Marine Geology and Geophysics, School of marine Sciences, 2002)
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Abstract:
In this study, an attempt has been made to find the textural, geochemical, sedimentological characteristics of sediments and water phases of the kayamkulam estuary located in the Southwest coast of Kerala, besides the impact of gas based thermal power plant located at the northern part of the estuary. Estuaries are an important stage in the transport of the solid weathering product of the earth’s crust. These weathered products or sediments are complex mixtures of a number of solid phases that may include clays, silica, organic matter, metal oxides, carbonates, sulfides and a number of minerals. Studies on the aquatic systems revealed the fact that it posses severe ecological impairments due to heavy discharge of sediments from 44 rivers, the continued disposal of pollutants rich materials from industries, sewage channels, agricultural areas and retting yards
Hariharan,G N; Nambiar,C G(Department of Marine Geology & Geophysics, School of Marine Sciences, 2001)
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Abstract:
The present work deals with the texture, mineralogy and geochemistry of bedload sediments of the main stream of the Chaliyar basin, a typical small drainage system of the tropics enjoying heavy rain fall and moderate climate, located essentially in the Northern Kerala and flowing over the crystalline rocks (and their laterized duricrust) of the South Indian granulite terrain. As the Chaliyar is the major river draining the Wynad Gold Fields and is known for its placer gold occurrences, the thesis gives special emphasize on understanding the nature and distribution of detrital gold in sediments of the basin, while attempting to infer the provenance characteristics and factors involved in the evolution of sediments in general. Minerologically the chaliyar basin sands are quartzose. The quartz and feldspar contents in the coarse sand fraction of the basin range from 64 to 86% and 2 to 16% respectively. The Q/F ration ranges from 4 to 38 with a slight decrease in the lower reaches. Other minerals present include, hornblende, pyroxene and heavy minerals like opaques, garnet, rutile, biotite, spene, silliminite, zircon, apatite and monazite some of which are seen as inclusions in quartz. The major element composition of Chaliyar bedload sediments in the main channel and the headwater tributaries is related to the mineralogical and textual characteristics of sediments.
Soney Kurien, P; Dr.Nambiar,C G(Cochin University Of Science And Technology, May 2, 2000)
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Abstract:
This report deals essentially with the geochemistry and petrogenesis
of Perinthatta anorthosite. The work also addresses the geological setting
of the pluton in terms of its field relationships and petrography and the
structure and metamorphism of the region and examines its relation with
the associated plutons. For the sake of convenience, the thesis is divided
into six chapters
Description:
Department of Marine Geology and Geophysics, School of Marine Sciences, Cochin
University of Science and Technology
Siby,Varghese; Chandramohanakumar, N(National Institute of Oceanography & CUSAT, 2003)
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Abstract:
Rare earth elements have occupied an important role in marine geochemical research, particularly as used in the format of REE abundance patterns to describe the geochemical pathways in marine sedimentation and authigenesis. This study concentrates on the distribution pattern of Rare earth elements in the sediments, behavior of Eu and Ce with respect to their occurrence in multiple oxidation states. It also concentrate the depth wise variation of sediment REEs from near shore areas (30m) to deeper depths 200m) in the Arabian Sea. It includes the downcore variation of REEs and other trace elements in the sediment cores and a comparison between the REE distributions of Arabian Sea sediment with the sediments of Andaman Sea. The study gives a general introduction regarding the importance of RRE studies, its occurrence and abundance, electronic configuration, lanthanide contraction, oxidations states and REE supply to the ocean, seawater and sediments.
Laluraj, C M; Dr.Muraleedharan Nair, S(Cochin University of Science and Technology, February , 2009)
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Abstract:
The metals present in the surface sediments have high demand on a
global perspective, and the main reservoir of these elements is believed to be
the ocean floor. A lot of studies on metals are going on throughout the world
for its quantification and exploitation. Even though, some preliminary
attempts have been made in selected areas for the quantitative study of
metals in the western continental shelf of India, no comprehensive work has
been reported so far. The importance of this study also lies on the fact that
there has not been a proper evaluation of the impact of the Great Tsunami of
2004 on the coastal areas of the south India. In View of this, an attempt has
been made to address the seasonal distribution, behavior and mechanisms
which control the deposition of metals in the sediments of the western
continental shelf and Cochin Estuary, an annex to this coastal marine region.Surface sediment samples were collected seasonally from two
subenvironemnts of southwest coast of India, (continental shelf of Kerala and
Cochin estuarine system), to estimate the seasonal distribution and geochemical
behavior of non-transition, transition, rare-earth elements, Th and U. Bottom
water samples were also taken from each station, and analysed for temperature,
salinity and dissolved oxygen, hence the response of redox sensitive elements to
oxygen minimum zone can be addressed. In addition, other sedimentary
parameters such as sand, silt, clay fractions, CaCO3 and organic carbon content
were also estimated to evaluate the control factors on level of metals present in
the sediment. The study used different environmental data analysis techniques
to evaluate the distribution and behavior of elements during different seasons.
This includes environmental parameters such as elemental normalisation,
enrichment factor, element excess, cerium and europium anomalies and
authigenic uranium.
Description:
Department of Chemical Oceanography,Cochin University of Science and Technology
Lasitha, S; Dr.Radhakrishna, M(Cochin University of Science and Technology, September , 2007)
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Abstract:
This work aims to study the variation in subduction
zone geometry along and across the arc and the fault pattern within the subducting
plate. Depth of penetration as well as the dip of the Benioff zone varies considerably
along the arc which corresponds to the curvature of the fold- thrust belt which varies
from concave to convex in different sectors of the arc. The entire arc is divided into 27
segments and depth sections thus prepared are utilized to investigate the average dip
of the Benioff zone in the different parts of the entire arc, penetration depth of the
subducting lithosphere, the subduction zone geometry underlying the trench, the arctrench
gap, etc.The study also
describes how different seismogenic sources are identified in the
region, estimation of moment release rate and deformation pattern. The region is
divided into broad seismogenic belts. Based on these previous studies and seismicity
Pattern, we identified several broad distinct seismogenic belts/sources. These are l)
the Outer arc region consisting of Andaman-Nicobar islands 2) the back-arc Andaman Sea 3)The Sumatran fault zone(SFZ)4)Java onshore region termed as Jave Fault Zone(JFZ)5)Sumatran fore arc silver plate consisting of Mentawai fault(MFZ)6) The offshore java fore arc region 7)The Sunda Strait region.As the Seismicity is variable,it is difficult to demarcate individual seismogenic sources.Hence, we employed a moving window method having a window length of 3—4° and with 50%
overlapping starting from one end to the other. We succeeded in defining 4 sources
each in the Andaman fore arc and Back arc region, 9 such sources (moving windows)
in the Sumatran Fault zone (SFZ), 9 sources in the offshore SFZ region and 7 sources
in the offshore Java region. Because of the low seismicity along JFZ, it is separated
into three seismogenic sources namely West Java, Central Java and East Java. The
Sunda strait is considered as a single seismogenic source.The deformation rates for
each of the seismogenic zones have been computed. A detailed error analysis of
velocity tensors using Monte—Carlo simulation method has been carried out in order
to obtain uncertainties. The eigen values and the respective eigen vectors of the
velocity tensor are computed to analyze the actual deformation pattem for different
zones. The results obtained have been discussed in the light of regional tectonics, and
their implications in terms of geodynamics have been enumerated.ln the light of recent major earthquakes (26th December 2004 and 28th March
2005 events) and the ongoing seismic activity, we have recalculated the variation in
the crustal deformation rates prior and after these earthquakes in Andaman—Sumatra
region including the data up to 2005 and the significant results has been presented.ln this
chapter, the down going lithosphere along the subduction zone is modeled using the
free air gravity data by taking into consideration the thickness of the crustal layer, the
thickness of the subducting slab, sediment thickness, presence of volcanism, the
proximity of the continental crust etc. Here a systematic and detailed gravity
interpretation constrained by seismicity and seismic data in the Andaman arc and the
Andaman Sea region in order to delineate the crustal structure and density heterogeneities a Io nagnd across the arc and its correlation with the seismogenic behaviour is presented.
Description:
Department of Marine Geology & Geophysics,
Cochin University of Science and Technology