VISION FOR R&D IN EARTH SCIENCES
Government of India
Ministry of Science & Technology
Department of Science & Technology
New Mehruali Road
New Delhi 110 016
Department of Science & Technology is promoting research in frontier and emerging areas through the Science & Engineering Research Council (SERC). SERC is composed of eminent scientists, professionals and technologists drawn from various universities, national laboratories and industries, and is assisted by a large number of Programme Advisory Committees (PACs) in various different disciplines. SERC has evolved, over the years, a unique peer review system which has been well-recognised by the scientific community. It has helped in promoting and strengthening of several new areas of research and established a large number of national research facilities, core groups/centres. It also endeavoured to promote the new concept of strengthening research capabilities in relatively small and less endowed universities/departments to increase critical mass.
The Council has recently reviewed its activities and areas of research which were earlier identified and has decided to update the areas for future support. Under the overall supervision and guidance of SERC, PACs in various disciplines have been requested to prepare to state-of-the-art document called "Vision for R&D" reflecting new challenges to the scientific community, national facilities to be set up including new ways and mechanisms of their promotion.
It is with this background that the Department of Science & Technology has decided to give wider publicity to these areas for promoting them in future. This document titled, "Vision for R&D – Earth Sciences" is for those who are interested in vigorously pursuing research in Earth Sciences. It is hoped that this document would be useful to the scientific community in planning their future research activities.
VISION PAPER ON EARCH SCIENCES
Man’s inquisitiveness about, and his dependence on, environment and the processes contributing to its change form the basis of studies in Earth Sciences. Over the years, our understanding of the processes operating in the Earth has increased considerably. This has led to a variety of new questions and new avenues of research. The emphasis today is to quantify the earth’s endogenic and exogenic processes which control its internal dynamics and shape its surface and fluid envelopes, the sum total contributing to global change. Such a study involves not only the contemporary events and processes, but also those of the past, as what we observe today is a cumulative effect of the past and present processes. More recently, study of the interactions among the various components of the Earth system-litho-sphere, hydrosphere, biosphere and atmosphere has gained considerable importance as these interactions influence global change on various spatial and temporal scales.
Studies in Earth Sciences in India are also slowly undergoing major changes. The current emphasis is to substantiate the classical approaches of exploration, description and data gathering through quantitative methods of data processing and interpretation of processes and event. The earth Science research is now evolving from a subject of individual inquiry to larger programmes involving scientists with complementary expertise and capabilities. Thus, the research programmes in geosciences are becoming more multi-disciplinary multi-institutional with increasing applications of the concepts and methods of mathematics, physics, chemistry and biology.
A major impetus for this shift comes not only from the need to understand and quantify better the spatial and temporal evolution of the lithosphere, with emphasis on the Indian segment, but also from the recognition that such knowledge could form the basis for the sustainable development of our natural resources. In addition, the recurrence of natural hazards has reinforced the need to learn more about the mechanics of these phenomena and to develop predictive modelling capabilities.
The emerging challenges require, on a continual basis, appropriate human resource development in terms of skills and expertise, as well as facilities and infrastructure. The direct interface of the Earth Science Programmes with exploration/exploitation of both renewable and non-renewable natural resources (like energy, groundwater and minerals) calls for a much closer tie-up of its R &D programmes with the industry, user agencies and concerned government departments.
India is a vast country integrating a variety of geological features and phenomena. These include the Archean cratons and their accreted mobile belts, the Himalaya – a classic example of continent-continent collision process-, the Deccan volcanic province one of the largest outpourings of continental flood basalts on the Earth’s surface, Proterozoic cratonic basins (Purana basins) of unique character, intra-continental Permo-Carboniferous coal-bearing Gondwana basins, well-preserved sections of major stratigraphic boundaries, some of the largest rivers of the world – the Ganga and Brahmaputra – and a variety of wel-preserved archives of past climates and environment. Extensive studies of these geological features have resulted in a number of important contributions in the field of Earth Sciences. Many of these studies stem from the thrust areas identified in the earlier DST document "Challenging Areas in Earth and Atmospheric Sciences". Some of the contributions under this programme are briefly given below:
Amongst the cratonic areas of the Indian shield, the southern Indian craton, commonly known as the KARNATAKA CRATON, received greater attention of geoscientists due to its attractive exposures of granulites and green stones. Investigations of fluid inclusions and their carbon isotopes have shown that CO2 plays an important role in the formation of charnockites from gneisses and metapelites. On the basis of integrated geochemical, isotopic, petrological and mineralogical studies it has been conclusively shown that charnockites formed under conditions of reduced activity of water, caused by dehydration melting or CO2 influx during recrystallization of the rocks at depth. Indian petrologists have also formulated, modified and refined a goods number of geobarometers and geothermometers for rigorous calculations of physical conditions of metamorphism of high grade rocks. P-T estimates on the basis of updated geothermo-barometers yielded values in the rage of 700-900° + 50° C and 6 – 10 kbars for the granulite facies metamorphism of these lower crustal rocks from southern India. Also, pressure – temperature-time trajectories have been elucidated for several granulite facies terranes which in most cases revealed magmatic underplating as a cause of tectonic thickening during the Precambrian crustal evolution.
Geochemical studies of greenstone belts of Karnataka craton, particularly of the Kolar Schist Belt (KSB), have shown plate tectonic signatures in the Late Archean times. The KSB is found to contain key features of suture zone along which western and younger eastern terraines have been juxtaposed. These conclusions have been drawn from difference in their geological history, geochemistry and radiogenic isotopic ratios.
Structural and stratigraphic studies in the Indian Precambrian shield have revealed gross commonalities in structural styles and multistage superposed folding in the three tectono -–metamorphic provinces of Karnataka, Rajasthan and Bihar-Orissa. Presently, emphasis is being shifted to ductile shear zones whose studies have led to the deduction of palaeostresses and changing patterns of structural geometry during progressive shearing movements. Such studies have documented non-coaxial deformation features, e.g. sheath folds, in the sheared granulite facies rocks amidst the Banded Gneissic Complex of Rajasthan, and in the Singhbhum Shear Zone.
Intensive studies on petrography and geochemical characterization of anorthosites and granites from difference tectonic settings, especially from the Eastern Ghasts Belt have revealed that the rock bodies are confined to the Proterozoic mobile belt, but show no clustering in the proximal shear zone. The anorthositic complexes are found to be cumulates and the nearly uniform composition of plageoclase megacrysts in some instances indicated isothermal crystallization at a nearly constant melt composition over a substantial period of time, although in the other situation a complex series of magma chambers in the crust was indicated.
Research in Deccan Volcanic Province has contributed significantly to the establishment of the stratigraphy of the basaltic flows, mainly along Western Ghats. High precision Ar/Ar dates for some of the flow sequences have revealed that the major eruption occurred during a short interval of 1-2 Ma, although the entire sequence spanned about 5 Ma. The bulk of the eruption predates the K/T event by 2 Ma. This has raised concerns about the palaeomagnetic correlations of the flows. From geochemical studies, the depth of melt generation, giving rise to the Deccan lavas in deducted to at least about 40 km.
Studies of sedimentary sequences in the Deccan Volcanic Province have provided a unique opportunity to assess the influence of large-scale volcanism on environmental shifts and extinction patterns. Studies on intra-and infra-trappean sequences include the discovery of a new eutherian mammal from the uppermost Mastrichtian sediments intercalated in a volcanic sequence in Naskal, Andhra Pradesh. This record of a South-Asian Cretaceous mammal suggests that the Indian Plate was not isolated from northern continents, despite other geological evidence to the contrary. Detailed assessment of the vertebrtate fauna pointed to a lack of endemism in India during the late Cretaceous. Extensive data on Dinosaur egg shells in the Narmada region of Central India established the typology and palaeophysiology of eggs, and the palaeo-environments of nesting sites. The nesting sites commonly occur in hard sandy carbonates beneath the basal-most basaltic flows and in the thin sedimentary horizons between flows. Some of the nests have been attributed to titanosuaroid sauropods. Five egg-sheell types have been recognised. Sauropod nesting occurred on a palustrine-pedogenic subaerial exposure surface coeval with the basal Deccan lavas. The wide geographic distribution of nesting sites in similar lithofacies across central and western India demonstrates strong nesting sites selectivity.
A new continental K/T site at Anjar has been discovered in the Deccan intertrappeans based on geochemical and geochronological studies suggesting that the K/T boundary layer results from bolide impact. The presence of several flows below the KTB layer implies that the Deccan volcanism was active at the time of impact. Furthermore, Indian scientists have emphasized that there is significant time lag between biotic crisis leading to extinction and the initiation of volcanism.
Stable isotopic composition of pedogenic carbonates from the Lameta Formation of Central India have been used to assess Cretaceous climatic shifts and to estimate atmospheric CO2 concentration during the Cretaceous. The carbon isotope composition suggests that the partial pressure of CO2 in the late Cretaceous atmosphere was about 800-1200 ppmV, consistent with global climate cooling towards the end of the Cretaceous. The oxygen isotope data suggest a highly seasonal climate with a pronounced continental effect because of larger size of Cretaceous India.
Combined isotopic-geochemical studies on the mafic volcanics in the Himalaya have established Late Archean (2.51 Ga) and Middle Proterozoic (1.54 Ga) lithospheric rifting episodes in the region, the former resulting in one of the world’s oldest flood basalt eruptions, the Rampur flood basalt province. These and other studies on the younger (Phanerozoic) mafic volcanics have also established repetitive additions of juvenile crust in the form of predominantly low-Ti tholeiites from sources which were (at least during the Precambrian) more depleted relative to the prevalent asthenosphere.
Structural studies in the Himalaya show that the NE plunging reclined folds and coaxial stretching mineral fabric have considerably influenced the tectonostraigraphic units of the Lesser and Higher Himalaya. It has been modelled into NE-dipping intracontinental ductile shear zone. This pattern predates the localised deformation pattern observed along major thrust boundaries. As an alternatives to "hot iron" model for metamorphic inversion, the classic Himalayan inverted metamorphism appears to have been controlled by small-scale displacement along ductile shear fabric. P-T data (780° C and 8-11 kbar) for K-feldspar – sillimanite grade rocks reveal exhumation of 25-35 km lower continental Proterozoic crust since Himalayan collision ca. 50 my ago. Extension tectonics, melt enhanced deformation and leucogranite generation in the Himalaya appear to be associated with decompression of the Himalayan metamorphic belt. Reactivation of rift-controlled basement faults have been postulated for the basin inversion in the Tertiary orogenic phase.
Research work on the river waters, particularly of the rivers originating from the Himalaya, has been very tantalising in regard to their chemical and isotopic make-up. Detailed studies on the major ion composition of the Ganga, Brahmaputra and Indus rivers show that their chemistry is controlled primarily by carbonate weathering and account for approximately 5% of global dissolved materials transported to the sea. However, because of their high relief, and monsson dominated climate the denudation rates in these basins recorded a much higher than global average. More importantly, some of these studies have brought to light the influence of the Himalayan orogeny on the Sr isotope evolution of the oceans since the Cenozoic. The source of high 87Sr/86Sr in the Ganga-Brahmaputra holds clues to be coupling between tectonics-weathering and climate.
During the last decade, a number of geophysical studies have been conducted to understand crustal structures beneath the various geological terraines of India. Some important findings are :
A wide angle reflection study, using deep seismic profiling over the selected transects have yielded the distribution of seismic wave velocity up to upper mantle and have identified anomalous high-velocity cushions (e.g. Cambay region) and low-velocity layers (beneath Koyna) in the lower crust and uppermost mantle. Vertical reflection seismic profiling in the Proterozoic Delhi-Aravalli belts detected a domal structure under the Delhi fold belt. This structure, in conjunction with the gravity signatures over the region favour a major magmatic underplating in the lower crust (at 15-35 km depth). The seismic tomographic study over the shield area has brought out a deep cratonic root (tectosphere) up to 250 km or more for the Dharwar Craton and a possible low velocity zone along the west coast, probably by rifting and/or plume.
Geomagnetic depth soundings in the NW region of the subcontinent reveal a first-order linear conductor, probably lying between 15-35 km depth. This major conductive anomaly seems to enter nearly transversely to the NW Himalayan collision belt. The more recently added magnetotelluric capability, constraining the electric structure of the crust, has been able to delineate (a) crustal conductors under the Deccan Volcanic Province, indicating the presence of fluids and/or rock-matrix with carbon dominated grain boundaries at the upper crustal depths, and (b) sedimentary structure below the thick basaltic cover in the Saurashtra region. The latter results suggest the presence of a Mesozoic basin below the Deccan Trap, which could not be delineated very well earlier by seismic methods.
Gravity observations, delineating the density structure of the crust, have revealed underplating of mafic material in the rift and mobile areas, particularly those influenced by the Deccan Trap. These studies have provided useful gravity anomaly maps on a regional scale which correlate well with the geology and tectonics of the Indian subcontinent.
An indigenous aeromagnetic capability has been developed for fast reconnaissance of our natural resource potential, particularly for diamond-bearing areas in Madhya Pradesh, Uttar Pradesh and Andhra Pradesh, and for assessment of Cuddapah basin. The method has been very gainfully employed to investigate large scale structures and basement tectonics along the Narmada-Son lineament and the southern most part of the Indian shield.
The geothermal datasets have indicated that amongst the various shield areas of the world, the Indian shield perhaps is the hottest. This is indicative of its fast rate of movement and greater thermal inputs due to crust-mantle interaction (e.g. rifting and mantle plume activity) since Jurassic period. Furthermore, the data also point out a substantial difference in the geothermal characteristics of the cratonic areas and those of the Precambrian mobile belts.
The launching of country’s own earth satellites has enabled the earth scientists to demarcate tectonic and contact boundaries of different major geological provinces based on multispectral reflectance data, leading to hypothesisation on the crustal evolution models which need to be validated or otherwise by field and laboratory investigations.
A major impetus in geophysical instruments has led to the development of airborne remote-sensing facility as well as resistivity measures which are being widely used in ground water assessment.
Earthquakes, in particular the intraplate ones, are major natural hazards. A study of Koyna earthquake of December, 1967 showed that the pressure changes due to loading were able to trigger seismicity with magnitude up to 6.5 or greater. Integrated geophysical investigations of earthquakes at Latur in the stable continental region reveal (i) a surface rupture zone, (ii) anomalously high helium levels, and (iii) a nearly coincident low velocity and high conducting layers at about 5 to 6 km depth below the epicentre (Killari). The last result is suggestive of the presence of fluids in this region.
Theoretical analysis by Indian geophysicists has yielded (a) an anomalous E M response behaviour of conducting targets covered by less conducting medium, and (b) thermal and rheological models for the Indian crust.
The palaeomagnetic studies have been attempted over a large number of areas with ages ranging from Precambrian to Recent times. One of the major results is the fast northward movement of the Indian plate since the Gondwana break up. High mobility of the Indian lithosphere has been attributed to thermal erosion of its base and/or warm sub-lithospheric mantle due to the presence of more than one plume during the past 120 million years.
Integration of geophysical study has brought out that plume/continental lithosphere interaction caused development of mid-continental geophysical anomalies and tectonic features. Thus underplating suggested by gravity signatures and supported by seismic studies could be considered as sniffer of the Pre-Deccan outburst event such as that existed in the NW part of the subcontinent. An exceptional focusing of the geophysical anomalies and thermo-mechanical activities observed along the mobile arms suggested that these may be acting as rheological wave-guides over a laterally heterogeneous continental lithosphere. Usng the deep mine observation, borehole data and fault-plane solutions, the Indian geoscientists have prepared a lithospheric stress map for the Indian plate. The main stress axes inferred at different locations do not always align with the direction of the plate movement – a matter for enquiry in immediate future.
In recent years the ability to recover climatic and environmental information from natural archives has been considerably enhanced through the use of isotopic, chemical and biological signatures contained in them. Multiproxy mapping of several of these continental and marine archives have begun to yield data on climatic parameters and the inter-relation among the various climate system components. For example, it has been shown that D/H ratios in cellulose from tree rings of Kashmir and 18O/16O in annual layers of corals from Lakshadweep of recent past can provide estimates of air temperature and sea water surface. Similarly, variations in the intensity of monsoon during the LGM has been tracked through oxygen isotope studies of foraminiferal shells from the Arabian Sea sediments and carbon isotope studies of peat bogs from Nilgiris. These studies show that during the last glacial maximum (~18 ka ago) and 4-8 ka ago the monsoon was weaker, whereas 8-12 ka ago it was stronger than at present.
Development of luminescence method for dating desert sands has opened new areas for palaeoclimate research. Studies in Thar Desert show that it is at least 200 ka old and that at present it is in a contracted phase. More importantly, the results indicate major dune building activities around 14,50 and 100 ka ago, during climatic regimes of re-establishment of south-west monsoon. These results suggest that studies on the temporal and spatial evolution of sand dunes in Thar can provide valuable data on the palaeomonsoonal conditions during the past 200 ka.
The size and extent of global ice-sheets constitute an essential boundary condition for all models of Quaternary atmospheric circulation. The paucity of data on the extent of Quaternary ice-limits from the Himalayan front has constrained attempts to model ice-age climate. Data collected from the Karakoram, Kunlun mountains, Hunza valley show that three to four glacial advances took place during the Quaternary. On the Indian side, similar evidence have recently been collected from the glaciers around the Nandadevi massif. A series of well preserved moraine ridges representing at least three glacial advances have been recorded in the Goriganga and Alaknanda river basins in Pithoragarh and Chamoli districts of U.P. respectively. Preliminary studies indicate that the glacier equilibrium-line-altitude (ELA) depressed by about 500m, 300m, and 200m in the past with reference to the modern. This would correspond to temperature decrease of about 3.3, 2 and 1.3 C, respectively. The occurrence of the terminal moraines suggests that the glaciers descended down to~3000 msl in these regions.
Late Quaternary land-sea interactions along a part of Saurashtra, West coast, India were documented to sift information on sea level changes using a morphodynamic approach. It has been demonstrated that the coastal tract remained tectonically instable throughout the late Quaternary time. A sequence of raised terraces, wave-cut notches, staircase platforms are the manifestations of emergence (more than 30m at places). These features are intrinsically related to fracture lineaments which correspond with the general structural configuration of the coast.
Eustatic high sea levels were identified on geomorphological considerations at + 7 m and – 13 m after making corrections for emergence. The younger sea levels had an overprinting of neotectonism. Well preserved oyster and clam shell samples collected from three sea level stands yielded ages of 126 + kyr, 87.2 + 9.7 kyr and 2.5 to 8.6 kyr. The first two age groups correspond well with the deep sea 18O stages 5e and 5a when sea levels were respectively +6 m and – 13 m compared to the present. The sea level corresponding to stage 5e along the Saurashtra was identified at + 7 m after making correction for neotectonism whereas the stage 5a shoreline at + 4 m confirms its emergence after its formation.
Studies of miliolite rocks from the Saurashtra coast suggest that they were formed predominantly during three periods, 60 + 10, 95 + 20 and 170 + 30 ka ago. The first two groups correspond to known high sea level stands at 60, 84-120 ka. These results in conjunction with the present day altitude of their occurrence yield uplift rates 0.2 – 2.0 mm/yr for this region.
OBJECTIVES AND RESEARCH AREAS
Considering the available results of the completed and ongoing research, relevant panel reports and existing scientific and social environments, the task before us is to identify areas which hold promise for creative excellence and for the well-being of society. It is expected that such themes and research areas would have a high likelihood of significantly enhancing our basic understanding of the geological processes/events and would yield results of general interest and application. This is indeed a difficult task even in the best of situations, because with the progress of research new questions continuously arise which could drastically change the directions of enquiry. Nonetheless, we are listing below a few themes/areas for pursuing future research activities to enlarge our understanding of the Earth processes. Other factors which have been considered in arriving at the list include : (i) the expertise of scientists, (ii) technology, manpower and financial support which are available at present and which may become available in due course, and (iii) the current international research trend. Additionally, future strategies in Earth sciences must take into account both basic and applied aspects in order to be able to cater to the ever increasing human requirements.
While indicating the future directions all areas/components of Earth sciences were not considered, and hence the topics listed below cover only selected disciplines.
Research priority themes in other areas, such as oceanography, limnology and atmospheric sciences, are being addressed to by specialized panels of the DST.
The above-mentioned areas have been briefly discussed in the following pages with regard to some emerging problems under each theme. But we must realize that all geological problems start in the field, and it is strongly recommended that field study be recognized as an inherent and pervasiv part of the research/education of earth sciences.
The major problem about the early crust relates to its origin and composition – whether mafic or sialic – and its growth mechanism with time. A general question of interest is : when and how all the "pieces" of all continents were formed, and the specific question in the Indian context arises as to when and how the different cratonic areas of the Indian shield were formed? Where these ‘blocks’ came from and how they were accreted into the Indian shield? Anser to these questions can be given primarily by geochemical and isotopic studies of the Archean crustal rocks. These rocks represented by the bimodal suite of tonalite-trondhjemite-granodiorite (TTG) and metabasics (? Relicts of early mafic crust) and can be recognized in the different cratonic areas of the Indian shield. Studies on the various geological units and associated phenomena form a topic of considerable interest for the evolutionary history of the Indian crust. In this endeavour, answers have to be sought for the model of crustal thickening (by continental collison and/or magmatic underplating), growth (vertical and/or horizontal), timing of different events of the crust-forming processes, e.g. subduction, collision, exhumation, uplift, processes of metallogeny associated with tectonics etc. Many of these studies are multidisciplinary in nature and involve investigations by many subdisciplines of geology and geophysics. These multi-aspect inferences of petrological, geochemical, geochronological, palaeomagnetic, structural studies need to be integrated to form a coherent crustal evolutionary model for the Precambrians of various segments. Some of the specific problems of the Indian crust are briefly highlighted as follows.
Amongst the half a dozen cratons of the Indian shield, the Southern Indian Craton is one of the classic terrains where extensive collaborative research in the last decade has provided much information on deep crustal processes (fluid-absent metamorphism vs. carbonic metamorphism). The different crustal blocks are found to exhibit a significant diversity in composition, structure, P-T-t path and isotopic signatures as well as the process of charnockitization. This raises a fundamental question on the origin of Southern Indian Granulite Terrain, whether it is an assembly of collided crustal blocks or fragmented Archean province (collisional or extensional tectonics). Palaeomagnetic studies along with signatures of metamorphism, deformation, geochemistry and radiometric dating are needed to resolve this crucial problem. A similar study is to be initiated in other cratonic areas, viz. Rajasthan, Bastar, Bihar-Orissa, and Meghalaya.
The Precambrian Orogenic Belts, which are-mostly peripheral to the cratonic areas, may offer answers to many crucial problems of crustal evolution. Geological studies of the Precambrian mountain chains provide critical data to test the applicability of plate tectonics model because these belts are ‘fossil’ plate margins. Research on these old fold belts provides a means to reconstruct the large structural changes in the crust that occurred over a long period of time. Geological information already available on these mountains such as the Singhbhum mobile belt, Aravalli fold belt, the Eastern Ghats Mobile belt, needs to be culled, starting from sedimentary basin development to deformation, metamorphism and igneous activity with support from new data on P-T and time (isotopic/geochronological studies). Through such a study it should be possible to resolve the models of Precambrian crustal evolution and the attempts to extend the concept of plate tectonics back in time. The eastern Ghats Mobile Belt (EGMB) is distinctly different from the Southern Granulite Terrain (SGT). The boundary between the two "provinces" is a thrust zone. By studying the tectonic style of the boundary and its metamorphism and by petrogentic and geochronological comparisons of the rock units from the two provinces, we would be able to model and explain the different histories of the two terrains -–Terrane accretion model vs. thickening by collision model. The available anti-clockwise P-T-t paths for the granulites of EGMB suggest magmatic underplating. The EGMB has an interesting problem with regard to its boundary relations with the adjacent cratons – Singhbhum cratonic block in the north, Bastar craton in the northwest, Eastern Dharwar in the west and Southern Granulite Terraine in the southern end. The western boundary, on the regional gravity database, appears to be a major easterly tilted fault with a throw of 2.5 km. It will also be interesting, petrologically and geochronologically to see if relics of incompletely modified crystalline basement containing older mineral paragenesis have escaped recrystallization during the Proterozoic orogeny of the EGMB and other fold belts.
The anorthosites and alkaline rock complexes of EGMB are potentially useful geochemical probes of their mantle sources. Information on magma sources and processes (during melting, in magma chambers and conduits), and on emplacement mechanisms of the complexes is of ulmost significance. Studies on the crystallization (including subsolidus) histories of the complexes (in terms of T, PH2O, f O2, silica activity etc.) are of inestimable value in understanding their evolution. The main problem that needs to be addressed about the anorthosites and associated leucogabbros, chromitites etc. may be stated as follows: Are these rocks dismembered oceanic crust or subducted oceanic lithosphere, or accumulated material of an underplated basaltic magma, or cumulates from precursors of tonalitic gneisses or cumulates complementary to greenstone belt basaltic volcanics?
From the study of thermal structure, recorded in the regional metamorphic characteristics (geothermobarometry), questions on the thermal history of the earth, e.g. how the earth’s crust reacted to changing temperature through geological time can be addressed. More recently, radiometric dating has shown that relics of incompletely modified crystalline basement in mountain chains still contain mineral assemblages formed in an older orogency, which may be expected to survive in the Precambrian Singhbhum and Aravalli orogenic belts, where rocks were buried during the younger orogeny.
The Purana basins provide unique opportunity to study unmetamorphosed Proterozoic sedimentary sequences, perhaps unprecedented in any part of the world except probably the Siberian shield. They contain an excellent record of the interactions between the lithosphere, atmosphere and hydrosphere during the period when the biosphere evolved from a nascent stage into a complex system. Data on the lithostratigraphy, sedimentology and the tectonic evolution of these basins are at best patchy and poor. Stratigraphic re-evalution of sedimentological, structural and geophysical, studies, critical examination of their biotic record, and focused basinal analysis, should be emphasized.
Recognition of intra-and inter-basinal unconformities, including focus on the possibilities of fossil-weathering profiles, high-resolution rhythmic phenomenon in these sedimentary sequences and documentation of their diagenetic histories, need to be detailed, together with efforts to better define the ages and duration of these basins.
Studies targeting the subsidence and exhumation histories of these basins need to be initiated, using various techniques. Geophysical examination and modelling of these basins need greater attention in conjunction with geological data.
These basins constitute an important tectono-sedimentary element of continental masses. These types of intra-continental basins need to be understood in terms of basin inception, filling and basin inversion. In India, isolated studies have been carried out on this class of basins, but integrated data sets on geophysical aspects, sediment thicknesses, high resolution stratigraphy (chronostratigraphy), and structural aspects are limited. The potential of integrated approaches for understanding rift basins, can be useful in studying the evolution of the Indian Lithosphere, most importantly in the late Paleozoic and Mesozoic, when the Gondwana break-up took place.
The Deccan Volcanic Province is geologically the most significant evidence of hot-spot volcanism. Models on the relationship between the mantle plume, rifting and continental flood basalt (CFB) exist. However, integrated petrological, geochemical, palaeomagnetic & geochronological studies are needed to obtain a more complete understanding of petrogenetic and geodynamic processes associated with the volcanism and to test the available models. Such studies are also essential to address questions pertaining to:
(i) The conflict between absolute ages & magnetostratigraphic data on the duration and hence the rate of volcanism,
Similarly, the basaltic volcanism of Rajmahal-Sylhet region in NE India requires investigation for its temporal and spatial relationship with the Deccan Trap and hence with the break up of Gondwanaland and opening of the Indian ocean.
The Panjab Trap, although not stupendous like Deccan Trap, denotes basic volcanism which overlaps beds of various ages from upper Carboniferous to Triassic. Its study will be of interest to understand the nature of deep crustal processes (e.g. decompression of mantle) in the NW India.
The Andaman-Nicobar islands have a special feature of being a conspicuous island arc to the east of Ninety Degree Ridge. These islands expose Tertiary marine sequence associated with ultramafic and mafic instrusives. These intrusions and other igneous rocks should be investigated for understanding the nature of arc volcanism and its relationship either with plume, rift or convergent margin processes.
The Himalayan orogenic belt is an ideal setting to examine large scale tectonics and the geological consequences of continent collision. Over the last decade, high resolution data on geochronology, geochemistry and structural set up have become available from the Pakistan and Nepal sectors of this orogenic belt. However, wide gaps in our knowledge still exist on the data base from Indian sector. The Indian scientists have gathered considerable amount of field data from the Indian sectors which need to be synthesised in conjunction with new results on geochronology and geochemistry. Such an attempt would provide an integrated view on several aspects of the evolution of the Himalaya. These include
(i) Pre-orogenic lithospheric rifting, mantle processes and development of ocean basin.
Scientific programmes on these themes, and on the different geotectonic sectors of the Himalaya, would enhance our understanding of the geodynamic evolutionary history of this orogenic belt and provide inputs to model these processes.
The Lithosphere – upper mantle with a blanket of crust – is a deformable solid outer layer of the Earth. Among the questions now confronting earth scientists under this theme are : How does the mantle drive plate tectonics (movement of lithospheric plates) and how does the core interact with the mantle? To answer these and other related questions interdisciplinary research is essential, inter-relating the various physical, chemical and geological processes that characterize the dynamic Earth. The imaging of deeper layers of the Earth by seismic wave velocity together with laboratory measurements of the physical and chemical properties of the Earth’s material would enable to model the structure, composition and dynamics of otherwise inaccessible portion of the Earth. The mantle composition and structures are determinable by geochemical analysis of mantle-derived materials and by seismic tomography respectively, which would reveal heterogeneties and thus density changes in the mantle. This, in turn would provide solution to the important question whether the mantle convects in one or two shells between the crust and the core. There is also a need to develop more rigorous models for earth processes, particularly for mantle convection and lithospheric deformation.
Studies of the continental crust and its margins is a primary focus of earth – scientists. The continental crust, being buoyant, escapes subduction during the plate tectonic processes and thus crustal rocks are likely to document evidence of lithospheric plate deformation. The rheological properties of the crust need to be determined by combined approaches of field and structural geology, experimental petrology and thermodynamics and by measurement of active crustal deformation rates now possible with the aid of satellites or Global Positioning Systems (GPS). The strains in the continental lithosphere are accommodated in the upper crust and an interdisciplinary study would give better understanding of deformation processes in the continental lithosphere, and of the complex processes such as volcanism, sedimentation etc. The structure of the continental crust of the Indian subcontinent can be obtained by deep seismic reflection profiling, refraction and wide-angle reflection methods. These seismic techniques would produce images of shear zones, intrusions and other deep features which, in turn, can help in modelling geological and tectonic evolution of the continental crust.
Fluids are responsible for distribution of mass and energy through the Earth system. Dominant fluid in the shallower crust is water while magmas are important at greater depths. Fluids promote chemical reactions, cause melting and metamorphism of rocks and play an important role in ore-forming processes, mountain building, triggering of earthquakes and landslides. Therefore studies of fluids, their presence, composition and flow should form an interesting research area in geosciences. To obtain information on the distribution of fluids within the crust the electromagnetic methods, including magnetotelluric and magnetovariational techniques, are useful geophysical tools. With growing ability to collect high density EM data both on land and sea and numerical facilities to deal with complicated three-dimensional structures, EM methods have important role in a wide variety of tectonic and economic geology problems. The possibility that EM methods can distinguish active faults from inactive ones by their conductivity associated with fluids, leads us to surmise that monitoring of conductivity distribution in seismically active zones may play important role in seismic hazard assessment and in using temporal changes in conductivity as possible earthquake precursor. The electromagnetic investigations carried out in the Himalaya and Latur region have unequivocally established connection between conductivity and seismicity. Therefore conductivity distribution in seismically active zones needs to be monitored as possible earthquake indicator. Although direct observations of hydrothermal fluids within the crust is difficult, the interface geochemistry of mineral/fluid assemblage is of fundamental importance both in the deep crust and within the mantle. Measurements of the chemical and isotopic composition of the fluids is required on materials such as rock-forming minerals, ore-deposits and partially – molten rocks in order to throw light on the nature and composition of fluids during geological processes within the crust.
The ability to simulate conditions of crust and mantle, to prepare synthetic minerals/gemstones, and to study physical properties and deformation of rocks, minerals and analogous material opens up the opportunities for experimental research in geosciences. High pressure, high temperature experimental devices such as large presses, small diamond anvils, and dynamic shock-wave apparatus would provide key data on the properties of material at pressures corresponding to the 670 km seismic discontinuity.
Many useful experimental phase equilibria studies and element partitioning studies have been made through the routine hydrothermal and piston-cylinder apparatus and recently with these advanced high-pressure instruments. Experimental studies of geologically simple and less complex systems have already been carried out at leading laboratories. These are now engaged in investigating more complex systems and path-breaking research activities. It is now important for the Indian experimental scientists to pursue very specific and still unresolved problems related to crust, mantle and core, instead of repeating what has already been performed, albeit with more sophisticated facilities. Recently the melting curve of Fe has been measured in shock-wave apparatus at high pressures corresponding to those at the core. These results enabled to estimate temperatures at the transition between the molten core and the solid inner core. From these estimates, temperature calculations are extrapolated both outward to the core-mantle boundary and inward to the Earth’s interior. Other high pressure experiments have estimated the composition and physical state of the molten core. These results when combined with seismic data obtained at the core-mantle boundary would throw light on the relationship between core-mantle interactions and magnetism. From this example it becomes obvious that Earth scientists in India need to develop inter-disciplinary research programmes in the experimental geology.
The Major objective of this theme to understand as to how the Earth system operates on a global scale by describing how its components parts interact at the crust-mantle and mantle-(EL) core boundaries. The dynamic Earth, like a thermodynamic engine, generates stresses and flows in solid and fluid materials, causing differential transfer of matter in geochemical cycles research on the crust mantle and core dynamics, therefore, requires integrated geological, geophysical and geochemical investigations. The most significant phenomenon of global interest is the subduction of lithosphere and its geological, geochemical and geophysical consequences which would enable us to explain many features of the Earth processes, besides giving a better understanding of the composition, structure and behaviour/exchange of material within the Earth’s deeper regions. Understanding of thermally induced convection in the Earth’s interior at various space-time scales is indeed necessary since this forms the main driving force for plate tectonics and mantle plumes. It is also very closely related to the generation of the internal magnetic field of the Earth, and its space-time variations. The geophysical imaging of Earths'’deep interior (from seismic, density, and electrical conductivity information) provides vital clues to constrain the geodynamic models of the Earth's interior. These images need to be supplemented by the experimental studies on behaviour of Earth'’ material at various depths and P-T conditions. Understanding the nature of the phase transitions at 660 km is a crucial problem wherein deep geophysical imaging and high-pressure high temperature experiments need to be focused. The nature, process, and dynamics of the core- mantle boundary are related to the upwelling of mantle plume due to instabilities developing at the D-thermal boundary layer. In the Indian context it is yet to be established whether the magmas erupted on the continental crust during Mesozoic had generated by the subduction process at the lithospheric depths or whether deep fractures, formed in the regions of the overlying plate, allowed partial melt from mantle to ascent to the surface. These and several other crucial problems of lithosphere can be resolved by geological seismic and other geophysical techniques including seismic profiling and refraction, heat flow, gravity, magnetic and electromagnetic methods and remote sensing. Obviously the combined geological mapping and seismic studies would help to understand the structure of the continental crust while geochemistry and phase-equilibrium studies would characterize its composition.
Seismic anisotropy studies of the Indian Lithosphere, using seismic tomography, geologic and geochemical properties, will also be useful to understand earthquake processes which are mostly manifested at plate margins. These studies will enable us to estimate parameters such a hypocentres, epicentres, origin time etc. This approach is essentially a nonlinear inverse problem of prime consideration and the results from a region would be useful in earthquake prediction. Active deformation of the lithosphere can be measured by recently developed techniques, namely Very-long-base-line radio interferometry (VLBI), satellite laser ranging (SLR) and global positioning systems (GPS). These techniques have proved useful in detecting relative velocities of the places and measuring regional strains on both continents and ocean floors, and require careful planning and coordinated research programmes on national and international levels.
The basic causes of earthquakes are strains induced by plate motions. The earthquake belts therefore demarcate plate boundaries – the zones along which plates collide, diverge, or slide past one another. Earthquakes are perhaps the most devastating natural disaster. India had two major earthquakes during the last decade, one in Uttarkashi, in the Himalaya, and the other in Latur, in the peninsular shield area. These earthquakes, particularly the one in the seismically calmer area of Latur, has placed considerable demand on the geophysicists of the country to have active observational and modelling programmes to better understand the various aspects relating to earthquakes. A single geophysical method often does not provide unique solution/model to the questions. In fact a simultaneous use of several geophysical methods coupled with non-linear inversion schemes can provide a better understanding of the structure and processes involved. The distribution of earthquake frequency, size, magnitudes, epicentre location etc., follow a power law which is a fractal distribution. The concept of fractals would help in understanding the mechanism of earthquakes.
Besides island arcs, continental margins are the major earthquake belts. In this context, the Himalayan regions, and in particular its shear zones, represent the potential sites for large magnitude earthquakes, Geophysical survey should, therefore, be aimed to find correlations of these shears and the generations of earthquakes. Also, faults are traverse the Himalayan rocks may also pose serious earthquake threats.
Detailed investigations using field geology techniques and seismological data are essential for locating buried active faults. Displacements along active faults can be established by combining historical record with stratigraphy, geomorphic analysis, remote sensing and age-determination techniques used in the paleoseismology. Deep crustal images can reveal the regional scale of low angle faults while seismological techniques help monitoring earthquakes which involve determination of the specific location, frequency of occurrence, and intensity of energy release. The study of these parameters involve diverse discipline, ranging from sedimentology, structural geology, seismology to geoengineering. For the Himalayan seismicity programmes, more regorous mathematical inversion techniques are required. Successful seismic and geodetic inversions may construct remarkable pictures of the fault-plane at depth and the associated complexities in both fault geometry and the process of rupture. Thus, there is a need for integrated geological and geophysical studies in the Himalayan region for better understanding of the earthquake processes, with involvement of institutions and scientists engaged in the Himalayan seismicity programme.
Lately, attention of earth scientists has been drawn towards the earthquakes occurring in the shield areas of the peninsular India, which was hitherto considered aseismic. Although plate tectonics explains the concentration of earthquakes in narrow belts of zones, it gives yet no satisfactory explanation for the occurrence of major earthquakes within the large plates, e.g. the Latur earthquake in the central part of the Indian plate. Intraplate earthquakes can pose a threat comparable to plate boundary events and thus require a systematic and detailed study.
Observation of occurrence of earthquakes in similar geological and tectonic settings elsewhere and comparison with the earthquakes which have occurred in peninsular India, has led to a belief among a section of earth scientists that the cause of all earthquakes can be traced to the dynamics of asthenospheric plates, which are responsible for the physiographic changes on the surface of the earth. Relatively large earthquakes are sometimes caused by reptures on faults are required to be located.
Research on the intracratonic microseismicity should include studies on reservoir-induced activity, upper to mid-crustal activity and brittle to brittle-ductile shearing in the cratonic region of India. The ultimate goal of all these systems would be to contribute to the development of a predictive model of earthquakes.
Geomorphology enables the detection of faults and other tectonic features in general through many of its parameters like the channel and network patterns of rivers and smaller streams respectively. Detailed studies of the landscape will help one to date its development and recognize evidence of neotectonism. By sorting out the faults, it is possible to eliminate those that can be considered dead and therefore not of any serious consequence from the point of view of generating earthquakes. The probable "active" faults can then be taken up for detailed instrumental verification, employing conventional geophysical methods of profilling – microgravity, magneto – (EL) telluric, resistivity, etc. Geodetic measurements using GPS and seismic tomography will facilitate microzoning of probable seismogenic regions. Such a multidisciplinary approach is an urgent necessity in the present scenario where major earthquakes occur due to neotectonic activities. The new subdiscipline of paleoseismology involves the study of earthquakes beyond the historical record through quantitative geomorphic analysis of the ages of the fault by combining sediment studies and dating of buried biological material therein.
The evolution of the geological features on the surface of the Earth is a continuing process and is influenced, among other by tectonics and climate. Studies on the evolution of these features are required for a better understanding of the associated processes, Sediments and sedimentary deposits on the surface of the earth contain signatures and clues to reconstruct past climate and global change. Some of the topics which hold promise for future work in the area are given below.
In the Cretaceous stratal records of India, e.g. the infra-and inter-trappean rocks and pedogenic carbonates, palaeoclimate and paleoenvironment, especially variations of atmospheric CO2 need to be studied, when the Earth system was showing unusual conditions such as rapid volcanism perturbed at least once by a bolide impact.
The regoliths in India are an ideal set of samples to study weathering, mobilization and accumulation of elements in soil-water system under a variety of climatic conditions. Special efforts are therefore required to motivate an interdisciplinary team consisting of geochemists, pedologists, stratigraphers and geomorphologists to initiate studies on our extensive regoliths including laterites to enhance our understanding of : (i) chemical and biological weathering processes and their rates in different climatic regimes, (ii) sequence of mineral weathering and mobilization / accumulation of elements, and (iii) the use of regoliths of obtain palaeoclimatic / environmental information.
Under this theme, Palaeosols hold a special potential as they can be used for verifying available models for atmospheric CO2 concentrations through the Phanerozoic, in particular in the late Palaeozoic and the Mesozoic of the Gondwana basins.
The Cenozoic stratigraphy record in India is unique as it offers the possibility of examining palaeomonsoonal records through long and short-term time scales. The Himalayan Foreland preserves continental sequences with abundant pedogenic carbonates, the latter holds potential for providing information on the development of monsoons in the context of uplift. Detailed integrated studies in well developed sequences (e.g. the Punjab sub-Himalaya) combined with exhumation / uplift rate determinations should provide a better understanding of the coupling between tectonics and climate. Such studies would also provide background data for climate modelling.
The role of uplift and chemical weathering of the Himalaya on the long term global climate change, particularly the glacial cycles is an important area of research. The coupling among these processes is inferred from the premise that there is extensive weathering of silicates in the Himalaya by the rivers, as evidenced from the highly radiogenic strontium isotope signatures of the Ganga-Brahmaputra. There is considerable debate on the source of the high strontium concentration and Sr/Sr of these rivers, their relation to silicate weathering, atmospheric CO2 budget and climate. This is an opportune time to take up observational and modelling studies on this topic, both of which would help enhance our understanding of the coupling between uplift, weathering and climate.
In the field of palaeontology, the following aspects need to have a priority during the next few years.
(i) For studies of high resolution stratigraphic boundaries related to chronostatigraphic events, India has a number of well preserved sections of the stratigraphic boundaries which are amenable for detailed studies. This includes PC/C boundary (e.g. Krol/Tal section of the Himalaya), K/T boundary (especially the Anjar Intratrappean section in the Deccan flows) and Neogene / quarternary boundary.
A major goal of the International Geosphere Biosphere Programme (IGBP) is to obtain a comprehensive understanding of the Earth’s climate system, particularly the complex interactions among the various Earth system components and their programmes depend on the retrieval of proxy records of past climate/environment from a variety of continental and marine archives which provide complementary information on various spatial and temporal scales. Such data help not only in providing a better perspective of the functioning of Earth’s climate system but also in testing various climate models. In this context, documentation of monsson variability over India and elucidation of the factors contributing to the variability should form a major component of palaeoclimate / environment research in India. Such a study would naturally require multi-(EL) proxy mapping of a number of continental and marine repositories, which can provide data on specific climate parameters over different spatial and temporal scales. The archives available include corals, tree rings and glaciers (high resolution recorders), peat bogs, deserts, loess, lake and ocean sediments (long term, coarser resolution recorders.) Methods and techniques to retrieve climatic parameters from all these archives have been developed and are available in the country. However, techniques for sampling of some of these archives, particularly long glacier cores and lake sediments, still need to be developed. The comparative study of continental and marine records provide information on regional factors contributing to climate change and help place more constraints on climate models. Furthermore, study of the ocean anoxia during the Quarternary in relation to atmospheric carbon dioxide variation is another important field of research. The ultimate goal of the programme should be to integrate and synthesise the data gathered from different archives to learn more about the cause-effect relation between monsoon variability and various forcing functions.
It is also necessary to reconstruct rainfall quantitatively, at least for the last 100 Ka, so as to be useful for climate models. Temperature is one of the main forcing functions of rainfalls and this can be constructed fairly accurately from speleothems. Special mention must be made of deserts which, being fragile ecosystem, demand our attention in understanding climate-dependent processes of desert expansion / contraction over different time scales, environmental management and groundwater resources.
In earth science applications, the prime consideration should be the well being of the society and industrial growth. Here, the thrust needs to be on the scientific study and proper exploration of natural resources (economic deposits, petroleum, coal, radioactive minerals etc.), exploration of groundwater, and awareness about the environment, particularly on pollution and natural hazards. Other issues include stressing geologic factors in the preservation of India’s heritage of monuments and increasing awareness regarding conservation of geologically important sites.
In recent years, the availability of water and its quality have emerged as a major constraints to economic development and quality of life. During the last few decades, creation of surface reservoirs and the associated irrigation canal network had formed the backbone of our water management strategy. Where the canal network could not reach, ground water has been heavily exploited for irrigation. A piquant situation has, therefore, arisen; whereas canal command areas face water logging and soil salinitisation, the other areas generally face declining water levels. The need, therefore, is to increase our ability to conjunctively manage all surface flows and ground water in a region, providing for drainage in water-logged areas and artificial recharge to over exploited aquifers. The scientific resource assessment should go beyound guestimates to quantitative analyses using tracers and computer based models to simulate the dynamic balance of water and to evaluate the consequences of alternate management scenarios.
The hard rock areas of the country face special problems due to the sub-surface void space being localized to regions of fractures and fissures resulting in limited ground water potential. The need, therefore, is to develop more efficient and reliable methods for locating zones of fractures and fissures and estimating their water yielding potential both under natural as well as stressed condition. In this connection, satellite remote sensing, using optical and microwave sensors may prove to be advantageous in identifying potential ground water areas. Tracers, both conventional and isotopic, can be used with advantage for estimating aquifer characteristics of potential and known ground water zones.
In alluvial areas where ground water availability is not restricted to zones of fractures and fissures, there has generally been large scale over exploitation of this resource. All over the country the need is, therefore, to develop innovative methods for conservation of rain water and renewal and reuse of waste water, wherever possible. While conservation is necessary to evolve methods for its sub-surface storage in large quantities in aquifers in an economical manner without endangering their water quality. In this context it is worth noting that as a result of over exploitation during the last four decades, both in hard rock and alluvial areas, we have inadvertently created a void space the volume of which is several times more than the total surface reservoir capacity in the country. Further, this reservoir space is more where relatively more use of ground water takes place. Successful exploitation of this space for artificial recharge of ground water under Indian conditions with highly seasonal rainfall, necessitates providing a temporary storage for the large volume of runoff generated during short spells of high intensity rainfall and accelerating its percolation to the water table. Innovation is also needed in waste water renovation technology in the urban areas where large volumes of municipal waste waters are generated. This is a year round assured source of water which, if renovated, can be used with advantage for ground water recharge as well as irrigation and some industrial applications. Soil acquifer treatment (SAT) systems may offer an economical alternative to conventional treatment systems. SAT involves letting in the raw / primary / secondary waste water to percolate to shallow aquifers through unsaturated zone (~ a meter) and pumping or otherwise discharging the water after receiving a treatment through some 100m or so of traversal within the aquifer.
The use of renewable waste water or the storm water for ground water recharge, can pollute the subsurface environment. In this process of ground water recharge, transfer of surface water to the subsurface is achieved through by passing the upper soil layers, which normally serve as an active filter to remove pollutants from the infiltrating water. Therefore, effective and safe technology for artificial ground water recharge requires inputs from (i) hydrogeology; (ii) hydraulics, and (iii) contaminant transport in the subsurface systems – an emerging area of research in earth sciences.
Many of the basic studies into understanding contaminant transport in the sub-surface environment will take a long time to reach maturity. This, in view of increasing use/misuse of systems which the sub-surface environment is being subjected to inadvertently, is perhaps the best reason to initiate these studies without any further delay. The emphasis should be on geohydrological studies that involve:
(i) Tracer studies to quantify aquifer parameters of potential and known ground water zones.
3.7.2 Mineral Resources and Fuels
Next to water, the study and proper exploration of natural mineral resources (metallic deposits, radioactive minerals, coal etc.) become the prime consideration for the well being of the society and industrial growth. Earth scientists have the challenging task for detecting natural mineral resources to maintain society with its basic resource requirements. Research in metallogeny and related fields is therefore required for understanding the crustal processes that form the mineral deposits, the environment in which these processes operate, and the distribution of deposits through space and time. From this understanding new deposits can be predicted, discovered and developed. Also, combining plate tectonic concepts with detailed geological, geophysical and geochemical data on the local scale would give a better understanding about mineral deposits. Modern analytical tools and techniques, such as stable isotope measurements age-(EL) dating systems, fluid inclusion studies, will be of immense help for geoscientists in selecting a hypothesis in regard to the formation and distribution of mineral deposits which are primarily located in cratonic areas and in rocks of mobile belts. Furthermore, skilled use of data-bases would provide the greatest frontier challenge in mineral resource research, because the interpretation of these data is needed by constructing and testing models of the genesis question. Current trends in metallogeny research in India require:
(i) Study of greenstone belts and their associated minerals, especially Au and PGE mineralization.
In the quest for minerals and fuels, different technologies have been developed, using geology, geophysics, geochemistry and remote sensing which can accelerate their research and locations.
Ultimate aim of studies in this sub-group should be for mitigating natural hazards, for example landslide, flood, drought etc., and for conservation of natural resources. A national programme is desirable to map the areas which are prone to or likely to be susceptible to these hazards. For each of the hazard types such as landslide, flood etc., a national map should be prepared which delineates the country into different zones.
Natural hazards caused by forces latent in the atmosphere or inside the solid earth need not only be predicted but also be diffused. Among such hazards are hurricanes and tornados, turbulence of sea near the coasts, earthquakes, floods, fires and landslides. The study of the causes of such occurrences and building up of their chronological record together with their impact on physiography of affected regions over the past 2000 – 5000 years calls for the application of different disciplines of earth science and integration of the observations made. If the calamitous effects of the natural hazards are to be warded off or diffused in time, it is imperative that their causes are scientifically investigated and understood by the application of earth science. Only then it will be possible to predict their occurrence with reasonable certainly.
India has a rich and varied history. The civilization and culture of India date back to Puranic ages; a lot of which is preserved and inscribed in different types of monuments spread all over the country. Natural elements and other forces, whether natural or mangenerated, tend to weaken their foundations, spoil their elegance and beauty, and disfigure these precious records of national heritage. It is a societal need to maintain and preserve these monuments. Here also, knowledge of earth science is useful to understand the nature of such harmful forces, and to device ways and means to preserve them, if need be, by relocating them to safer sites. In the selection of such sites too, earth science can be used profitably.
Again, some of the classical and instructive geological sections and outcrops in the country need to be preserved for posterity for their scientific import, so that they are not subjected to vagaries of nature and man. It is imperative that this rich heritage should be conserved by the government / scientific institutions.
The geological sciences draw on tools and knowledge developed in other scientific disciplines. At the same time, geological research has contributed concepts and techniques to these other disciplines. For example, the structural determinations of high-temperature superconductivity drew heavily on mineralogical principles and the similarity between the perovskite structure of these superconductors and mineral structure of large parts of the mantle is an example of close relationship between geoscience and physical sciences. From the curiosity of studying geological materials on submicroscopic domain, the earth scientists also developed or refined several analytical devices (e.g. EPMA, lon Probe, High P-T equipments) that were then applied in many other fields.
Increased understanding of the Earth process as well as emerging newer concepts and methodologies require interactive research programmes involving geoscientists, physicists, chemists, biologists and mathematicians. For molecular phyllogenetics a paleontologist has to interact with biologist and organic chemist. Similarly, a petrologist and mineralogist would need a physicist to peep into the intricacy of heat and mass transport problems associated with matter in subcrustal depths. Even within earth sciences most research works are multidisciplinary about which an emphasis has been given in this document. Interactions seem to be legion, and most frontier research topics relate to more than one theme. Again, present day computational capabilities have revolutionized the handling of vast amounts of data generated in earth science research. We now require to develop quantitative models for a number of earth processes. Even such traditional disciplines, as mapping and paleontology, are becoming increasingly quantitative with advent of digital analysis and computerzied data base. The main emphasis of this theme is to recognize research problems in geosciences which need to be seen from different angles since solid earth of geoscientist is in a way a science of solid state physics. To account for several earth science phenomena we also need to develop theoretical / mathematical models. Compilation of geological history and study of modern processes and their rates would allow mathematical modelling. For example modelling is required for geochemical cycling, which brings together results from studies of various aspects, including mantle evolution, global tectonics, rock-water interactions, organic evolution, global tectonics, rock-water interactions, organic evolution and paleoclimatology.
Numerical computer simulation is needed to develop, rather more rigorously, for a number of earth processes involving inputs from physical chemistry, statistics and other fields. We need accurate projection of the data-based interpretation for prediction of the natural processes. Even Chaotic system are subjected to statistical prediction. For example, the quantitative treatment of isotope exchange between rock-minerals and fluids need intensive integrated research in fluid-rock interaction and fluid flow within the crust. Many research problems of integrated nature can be conceived and formulated, byt only a few are mentioned below.
In igneous petrology where study of silicate melts is made, geochemistry is definitely an essential research component. But to advance our understanding of many related processes, such as element partitioning between melt and crystals, crystallization sequence of minerals, etc., a full knowledge of silicate melt structure is necessary. For this we need interaction with physicists and chemists. To study viscosity behaviour of melt, solubility of water in the silicate melts and structural nature of the melts, we need Raman Spectroscopy and polymer chemistry and related fields. In addition, spectra of ferrous / ferric iron requires knowledge of Mossbauer spectroscopy and crystal structure. Furthermore, to elucidate the petrogensis of diversified igneous rocks, Rayleigh fractionation equation are used for elemental data so that vector calculations can be made for representing the composition of the derived liquids (resulting from the removal of given phases) and of cumulates (resulting from crystallization of model liquid). Clearly, we need inputs from experimental studies of crystal / liquid and element partitioning between them.
The lithospheric evolution of the Indian region forms an important interactive research area that would involve seismological, heat flow, magnetic, gravity, electrical, isotopic and geochemical studies of specified segments / transects in India. The studies may be carried out in stages as multidisciplinary research project.
A long-term approach in metamorphic petrology is to outline P-T-t paths which indicate dynamic time-dependent character of metamorphism for a given crustal segment of overthrust belt. The geothermobarometry, based on thermodynamic principles, when applied to zoned minerals or to incompletely reacted mineral assemblages would help to define the paths of pressure / and temperature variation followed by the individual rocks. Chemical data on the zonation of minerals would additionally provide a wealth of information on the thermal processes that took place during metamorphism of rocks and growth of minerals. This shift of metamorphic petrology from a static mode (which report the mineral assemblages found in the field) to a dynamic mode (aimed at working out the mechanical and thermal processes involved in metamorphism) needs numerical modelling. In this effort the thermal response of the rocks to tectonism can be determined by computer modelling of the transient temperature distribution in a rock mass of specified physical properties, assuming certain boundary conditions. This forward approach complemented by petrological observations would unravel details of thermo-tectonic evolutionary history of rocks.
The successful implementation of research programmes in any field requires personnel in various categories, appropriate infra-structural facilities such as equipment, current books and journals etc. India has a welath of experienced earth scientists, but many of them are trained primarily in the classical approaches and are very specialised. The need today is more broad based and earth scientists with very good background in basic sciences, particularly mathematics and physics and chemistry are required to carry out many of the interdisciplinary programmes and develop capabilities for modelling the results. In the context, there is a need not only to overhaul the current compartmentalised education system in earth sciences in the universities, but also to encourage scientists from basic sciences to immigrate to various areas of earth sciences. The earlier PAC had prepared a detailed document on Earth Sciences Education in India (Current Science, Vol.67, No.2, 25 July, 1994).
To ensure front line scientific research in earth sciences, a continuous series of training programmes by way of workshops, summer schools, advanced short courses in selected topics, are required to be encouraged. Contact programmes need to be initiated particularly in institutions where infrastructural and instrumental facilities are available such as the WIHG, NGRI, PRL, IITs etc. Interdisciplinary teams must be motivated to prepare instructional materials for dissemination. Refresher courses in modern trends in earth sciences with basics is physics, chemistry, mathematics and computer applications, mostly of remedial nature, should be formulated and distributed to various institutions / universities largely through video-lectures and correspondence materials.
Research in earth sciences, or for that matter any other disciplines, is considerably influenced by current awareness which in turn depends on the availability of a wide range of journals both basic and applied. Indian universities, for some time now, in the recent past, are faced with a major financial crisis, particularly in respect to library grants. The situation requires immediate redressal by way of long and short term measures. As a short term strategy, there is an immediate need for five to six regional units equipped with computer data base, such as GEOREF together with the required infrastructure for the dissemination of library materials to other users.
Earth Science data rely heavily on precise measurements. Collection of these data, particularly those dealing with geochronology, isotope systematics and chemical compositions, require sophisticated instruments. This is an area where most of the Indian laboratories lag behind the international scene. Consequently, we need to strengthen and augment the instrumentation facilities so that the country’s research efforts can be maintained at an internationally competitive level. The approaches for strengthening and updating the instrumentation facilities are discussed in detail in separate document prepared by the PAC on this topic.
The potential and promise of research in Earth Sciences in India, both in basic and applied areas, are vast. The areas delineated in this vision paper should be interesting enough to stimulate a scientist in his / her imagination and to identify a specific problem, suiting his / her background, resources and infrastructural support that he / she may muster. The time is now opportune to follow up some of the most challenging themes intensively by launching national programmes (interactive / multidisciplinary) through appropriate linkages between industry, universities, government agencies and national laboratories and survey organisations. Through these coordinated efforts and interaction between scientists of related and varied specialisations we are expected to generate a more positive research environment whereby scientists would have access to library and instrumental facilities, with their maximum utilization. As a consequence, these would result in excellent research in the country whose spin off would naturally be toward the development of technology and science that would foster country’s economic growth and meet societal needs as well as enhance defence, archaeology, dam, irrigation and geotechnical activities.