MANDAL , DEENDAYAL

English

Open Access Repository of Indian Theses

Abstract Chapter 1Human being, with a very short life span, has expanded his conception of the durationof time, in order to study his own planet earth and the various processes that arecontinually operating on it through geologic times. The coda of this geologic time,represented by the Quaternary period, is accorded with the highest interest andsignificance due to its proximity to the present age and most importantly, it ischaracterized by the emergence and development of the hominids.The Quaternary period has witnessed series of frequent and rapid climatic changesalong with epeirogenic movements, which in turn had continually modified thesurface expressions of the continents. This second period of Cenozoic Era represents atotal span of about 1.8 Ma and has been sub-divided into Lower Pleistocene (1.8 –20.75 Ma), Middle Pleistocene (750 – 125 Ka), Upper Pleistocene (125 – 10 Ka) andHolocene (10 – 0 Ka) comprising thick accumulation of sedimentary deposits.The south Gujarat alluvial plains, occupying a significant position along the westernmargin of Indian sub-continent, comprise considerable accumulation of theseQuaternary sedimentary deposits. Owing to its uniqueness from the point of view ofgeomorphic diversity and climatic significance, these alluvial plains represent one ofthe most important and interesting segments of the west coast of India. Climatically,the south Gujarat terrain is represented by an overall humid tropical type, with a goodseasonal rainfall and the presence of perennial river systems, characterized by awestward flow. These river systems, which form one of the most important geologicagents on the earth, had continually sculptured the landforms of south Gujarat terrain.The northern portion of the south Gujarat alluvial plains is demarcated by the lowerTapi river basin (LTRB) i.e., the study area, which is characterized by the presence ofQuaternary deposits. The LTRB has its own distinct identity in terms of sedimentationpatterns vis-à-vis active tectonism and climatic vicissitudes. It is characterized byvariety of landscape as well as tectonic features along with a well-developed drainagenetwork. The LTRB also comprises an interesting assemblage of well-preservedpalaeo-geomorphic landforms and tectonically accentuated features. However, aglance through the available literature has revealed that the LTRB has received lessattention from the earlier workers and not much work is reported, except meagerinformation merely highlighting the geomorphic setup of the south Gujarat as a whole.Hence an attempt has been made through the present study, to comprehend the role ofvarious geological processes operating in the LTRB and also to envisage the overallsedimentation history vis-à-vis the role of neotectonism during the Quaternary times.Although these geological processes seem to be infinitely slow today, but over a3period of several thousands of years, have resulted in the present-day landscapeconfiguration.The LTRB is located on the threshold of semi-arid and humid climatic domains andits northern and sout hern boundary is distinctly demarcated by the presence of Kimand Purna rivers respectively; whereas the trappean highlands and the Arabian seadelimits its eastern and western boundary respectively. The LTRB constitutes a thickpile of Quaternary sedimentary deposits resting unconformably over the Tertiary andTrappean basement. Tectonically, the LTRB forms a part of the two major pericontinentalrift basins i.e., the Cambay and the Narmada rift basins, which seems tohave governed its tectonic setup. It is also evident that the episodic reactivation alongthese tectonic elements coupled with the climatic perturbations, have controlled thesedimentation pattern and geomorphic evolution of the landforms in the LTRB.Owing to this, a multi-disciplinary approach has been adopted in the present study tounderstand the intricacies related to the Quaternary sedimentation in the LTRB. Thecombined evidences from the extensive field observations, sub-surface bore-hole data,precise laboratory investigations and various other persuasive studies, have helped inthe reconstruction of the basin configuration of the LTRB, its sedimentation historyand the governance of tectonism over it, during the Quaterna ry times.Chapter 2The study area forms an integral part of the three major tectonic elements borderingthe western margin of India such as the Cambay, Narmada and Tapi, comprisingvariety of geological formations, ranging in age from Proterozoic to Recent. Althoughmajority of the geological formations are reported in the subsurface data, however theexposed outcrops belong to Deccan Traps, overlain by Tertiary and Quaternarydeposits.The geological aspects of the lower Tapi river basin ha ve received less attention fromthe earlier workers. Blanford (1867) gave the earliest account on the geologicalattributes in his memoir on the “Geology of the Taptee and lower Nerbudda valleysand some adjoining districts”, followed by Foote (1898), who had described the vast10alluvial stretch between Kim and Tapi rivers. Various other contributions related tothe geological aspects, directly or indirectly pertaining to the LTRB, have beenprovided by several workers associated with institutes such as, Geological Survey ofIndia, Directorate of Geology and Mining, Government of Gujarat, Oil and NaturalGas Corporation Ltd., National Geophysical Research Institute, Hyderabad and the M.S. University of Baroda.Chapter 3This chapter is mainly concerned with the systematic description and interpretation ofthe present day as well as the past geomorphic features in the study area, taking intoaccount the field observations aided with remote sensing techniques, and groundchecks. According to Davis (1909), the geomorphic processes and the prevailinglitho-tectonic framework along with the climate, plays a significant role in controllingthe successive sculpturing of the landscape configuration of that region, withincreasing time.The south Gujarat area in general and the study area in particular aptly represents anassemblage of diverse geomorphological features exhibiting a complex interplay ofvarious erosional as well as tectonic processes (Scheidegger & Padale, 1982; Vyas,331984). Earlier workers (Radhakrishna, 1965; Scheidegger & Padale, 1982; Ollier &Powar, 1985; Alavi, 1990) have attempted to describe the various geomorphicattributes of south Gujarat terrain; however, no specific studies have been made so faras the study area is concerned. The present study is aimed to bring out systematicanalyses of these features and the factors responsible for their genesis with the help offield observations and satellite data (IRS-1C LISS III, 1998) (Fig. 3.1).Chapter 4“Neotectonism” has been one of the most familiar terms amongst the geoscientists,engaged in unraveling the Neogene and Quaternary history, throughout the globe.This term was first introduced in the literature by Obruchev (1948), to describe thestudy of the young and recent movements taking place at the end of the Tertiary andthe first half of the Quaternary periods. Stewart and Hancock (1987) have defined“Neotectonism as a branch of tectonics concerned with the understanding of earthmovements that occurred in past and are continuing in the present day”. Mukherjee(1980) has defined “Neotectonics as the study of structures of the earth’s crust createdby the latest movements, having a distinct influence on the formation of present daysurface relief”. According to Slemmons (1991), “Neotectonics can be broadly68described as tectonic events and processes that have occurred in post-Miocenetimes…”. Although neotectonism has been defined in various ways by severalworkers, however Morner (1990) is of the opinion that the neotectonic phase starts atdifferent times in different places, depending on the tectonic regime.The south Gujarat in general and the study area in particular, have not remained anexception as far as neotectonic activities are concerned. The studies carried out inthese areas, have clearly demonstrated the influence of these activities, persistedthroughout the Quaternary times. Owing to the potential nature of the study area andits surroundings in terms of the neotectonic activities, the present study is aimed tounderstand the role of these activities and their signatures, well imprinted on itsgeological and geomorphological expressions, mainly based on the field observationsand sub-surface data. The following paragraphs furnish a detail account of theneotectonic signatures observed within the study area and their vital role in theQuaternary history of the terrain.Chapter 5The contents of this chapter forms a part of field investigation, dealing with the study of theQuaternary sediments that occupy the various cliff-sections exposed all along the major riverchannels such as the Kim, Tapi and Mindhola as well as their tributaries, in the study area, inorder to bring out a systematic record of the stratigraphy, spatial distribution pattern andsedimentary characteristics. The sedimentological studies include the identification of variouslithological units, their vertical and lateral relations hips with the adjacent units and theirlateral mapping, in order to understand their continuity and extent. Along with the mappingof the lithological units, due emphasis has been given on the identification of primary as wellas secondary structures wherever observed. The representative samples of each of thelithological units have been collected by means of trenching of the entire cliff-sections, forfurther laboratory investigations.88Although, the sedimentological studies have been attempted for the lithological units exposedalong the cliff-sections, however, an attempt has been made to incorporate the bore-holeinformation so as to understand the sub-surface details of these sediments and to bring aboutthe overall Quaternary basin configuration.The succeeding pages of this chapter, provides the location-specific sedimentological detaChapter 6The contents of this chapter reflects the observations pertaining to the detail laboratoryinvestigations carried out for the representative samples of the various lithological unitsexposed within the Quaternary successions along the Kim, Tapi and Mindhola river valleys.The various laboratory techniques adopted in the present study includes the hand specimenobservations under binocular microscope, granulometric analyses of arenaceous sediments,X-ray diffraction studies for mineralogical details, scanning electron microscope studies forsurface morphological attributes, geochemical investigations for trace element concentrationsand micro-palaeontological analyses. The results obtained from the laboratory investigationshave been interpreted and integrated to understand the influence of various processes during129the deposition of Quaternary sediments within the study area. The succeeding pages of thischapter provide the detailed account of each of the laboratory techniques employed in thepresent work and their results so obtained.Chapter 7The preceding chapters of the present study have provided an elaborate information ofthe observations made on the nature of exposed Quaternary sediments of Lower TapiRiver Basin (LTRB), their lateral as well as vertical distribution, field characteristics,geomorphic and tectonic vicissitudes and laboratory details. The contents of thischapter mainly focuses on the integration and interpretation of the results to bring outa comprehensive picture of the sedimentation history during Quaternary – Holocenetimes, encompassing pre-Quaternary basin configuration, stratigraphy, depositionalenvironments of the sediments vis-à-vis the role of tectonism, sea level fluctuations,climatic changes and geomorphic processes.

Fungal Mediated Biotransformations Of Organic (Carbonyl Group) And Inorganic Compounds.

http://eprints.csirexplorations.com/177/1/Abstract.doc

Fungal Mediated Biotransformations Of Organic (Carbonyl Group) And Inorganic Compounds.

Abstract

Similar works

Full text

Available Versions

Open Access Repository of Indian Theses