The geological horizon

By C. V. Gopalakrishnan

THE ANNOUNCEMENT by the Oil and Natural Gas Corporation (ONGC) Chairman and Managing Director, Mr. Bikash C. Bora, of the its ambitious plans to launch a major restructuring of the Bombay High oil fields at an estimated cost of Rs. 5,000 crores should also remind us of the dead-end which the country's oil exploration programme has reached. The euphoria over the discovery of oil in Bombay High in the mid-1970s and the hopes about India soon becoming self- sufficient in oil evaporated by the 1980s when it came to light that a large number of wells in the offshore area were becoming sick and production was declining. The ONGC's total oil production, bulk of which comes from the Bombay High, has fallen from 31.63 million tonnes in 1995-96 to 24.65 million tonnes in 1999-2000 and could be even less in 2000-01. Promises held out by the more sprawling Bombay Offshore might, however, materialise, though the huge investments this would call for imply major policy decisions: whether it would not be wiser to resort to imports instead of incurring capital as well as running expenditure on the extraction of oil, a non-renewable source.

The major change in perceptions about oil as a mineral resource - from the almost frenzied effort which almost every non-oil producing country, including India, was involved in to make itself self-sufficient to the issue now ceasing to command that much importance - could be attributed to a development which the oil-producing countries might not have anticipated. The dizzy price of oil in the global market during the 1970s led to increases in the prices of everything which the other countries were exporting. Of greater interest, however, are other questions provoking an awareness of oil being a non-renewable fossil fuel. This should shift attention to other areas of as much importance. Among the non-renewable minerals, crude oil is the only liquid, though its viscousness prior to its refinery fractionation into high speed and light diesel oil, kerosene, petrol, bitumen, low sulphur heavy stock, liquified petroleum gas (LPG) etc., should virtually make it immobile wherever it is located.

Nevertheless, his hopes about crude oil migrating from land to sea led to the former Petroleum Minister, K. D. Malaviya, backing the launch of drilling operations both in the Godavari and the Cauvery offshore areas. These, however, had only limited success. If crude oil does have a migrating propensity, very little is known about it.

Whether it is crude oil or other non-renewable, depleting reserves such as metallic ores, India seems to have them only in small quantities scattered over a very wide area; though this has not discouraged geologists from studies and efforts to recover them. The studies which the Geological Society of India, Bangalore, has been carrying out for years cover the geology of not only Karnataka but also other parts of the country. A subject it had taken up seriously for consideration was the adoption of scientific exploration techniques for the optimal use of the country's mineral wealth.

The extent of international attention which India's mineral resources has invited could be seen from the interest taken by the Department of Geology, University of Oulu, Finland, about a decade ago. Of considerable significance is the fact that geological turbulences over the ages have not brought about any significant migration of the chemical constituents. Had such migration taken place, it could have obliterated the original sedimentary structures. Geological studies carried out by the Department of Geology, Oxford Polytechnic and the Research School of Earth Science, Canberra, have thrown light on how dehydrating fluids which were probably rich in carbon dioxide acting as ``the agents of metamorphism'' (which refers to the geological transformation brought about by heat and pressure).

There have been theories - though none of them have been conclusively proved yet - that the moon was part of the earth from which it had been torn apart from the primordial Pacific Ocean and hurled away 2,50,000 miles to become a satellite. Geologists, however, seem to have some evidence of it in the ``Lonar Crater'' of Maharashtra, so-called because of the evidence of its meteorite origin. While searching for meteorite fragments, the geologists found scattered particles of glass on the western side of the crater. A systematic study later revealed that the glassy material was ``profusely concentrated symmetrically on the east and west sides within a radius of 500 to 600 feet commencing from the middle of the outer slope. Besides, a sandy concentration of glass is observed at some places in the cultivated fields''.

A thorough study of the ``impactites'' found in the crater indicated the possibility of their meteorite and lunar origin was also supported by the underground structure in the impacted area beneath the silt bed in a lake. It showed highly crushed and fragmentary rocks which were designated ``breccia lens''. The probability of a meteorite hit and its lunar origin, the will, however, have to be studied further before there could be any confident pronouncement about their extra-terrestrial origin.

Though the crater's origin is still being regarded as terrestrial, professors of the Smithsonian Institution, Washington, the GSI and the U.S. Geological Survey in a detailed analysis of the scattered objects in the Lonar Crater are of the view that the crater provides unique opportunities for comparison with lunar samples of ``shocked basalt''.

The state of preservation of the objects and their ``comparative youthfulness makes the Lonar Crater of Maharashtra a particularly rewarding site for studies of impact structure, petrography and geochemistry''. There is yet no indication, however, in the debris scattered in the Lonar Crater of what would be immensely exciting to everyone - viz. of their chemistry being wholly unrecognisable and different from that of what we find on earth. However, enough is known about the planets at least in the solar system sharing the same chemistry as that of the earth. If, as it is very likely, the planets of the other far away galaxies are wholly alien in their chemistry and geography, it is going to be a long time before we come to know about it.

The mineral exploration carried out so far by multi-disciplinary experts suggest that the launching of at least a few projects would have commercial viability. They have carried out detailed studies in stratigraphy which explores the relative positions of geological strata - the order in which metallurgical and non- metallurgical ores were placed over several million years during which they have remained buried in the bowels of the earth. Of far greater significance than such matters of specific interest to geologists, however, is the striking placement of petroliferous, metallic and non-metallic deposits several billion years ago a few thousand metres below the surface of the earth, either by accident or some cosmic design.

Thoughts about the velocity at which they should have struck the earth and pierced it to a few thousand metres are indeed mind- boggling. If, as it is almost certain, such placement had taken place long before the earth had broken off from some pre-historic integrated solar system, scientists now have evidence of the other planets being just as richly endowed with such subterranean riches though ours is the only inhabited planet. It is perhaps just as well that the other planets still remain beyond human reach and greed.

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