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1986 | Buch

The Indian Ocean: Exploitable Mineral and Petroleum Resources

verfasst von: Dr. Ganpat Singh Roonwal

Verlag: Springer Berlin Heidelberg

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Über dieses Buch

Exploration of marine minerals by geologists and oceanographers started more than a century ago, but at that time this type of work was largely confined to the intertidal zones and shallow waters, as these areas were easily accessible. There are also records of several investigations carried out during the famous Challenger expedition in the deep sea. Since then, marine geological and mineral explorations have progressed considerably, and our knowledge of the sea at depths ranging from 4000 m to 6000 m has increased accordingly. With this development has emerged also a change in the understanding of the resources of the seabed. At present, the seabed has become a focal point of studies, not only on petroleum and other mineral resources, but also on its own evolution in the history of the earth. The concepts of continental drift and plate tectonics being well established, further surveys and exploration have helped in establishing a relationship between the origin of the oceans and the mineral potential that exists in their floor. The Indian Ocean had its birth with the dismemberment of Gondwanaland. The seabed of the Indian Ocean contains minerals ranging from beach sand and gravel to heavy minerals associated with beach deposits. There are also surface occurrences of phosphorites and manganese nodules and sub-surface deposits of petroleum and various other types of mineral. The author of this book, Dr. G. S. Roonwal, has presented several aspects of mineral resources of the Indian Ocean.

Inhaltsverzeichnis

Frontmatter
Chapter 1. Introduction
Abstract
On the ocean floor lie vast quantities of mineral reserves. Among the primary mineral resources presently known are rich deposits of metalliferous mud and manganese nodules comprising zinc, copper, silica, lead, nickel, and cobalt and others such as phosphates. Common salt, magnesium, and bromine have long been extracted from sea water; sand and gravel, tin-bearing sands, magnetite sands and calcium carbonate are already being mined.
Ganpat Singh Roonwal
Chapter 2. Origin and Development of the Indian Ocean
Abstract
The history of science is full of bold hypotheses, many of which have proved to be true. This was so with the concept of continental drift, which holds that all the continents were once joined in a single great landmass, named Pangaea, “all land,” the name proposed by A. Wegener in the 1920’s. This universal continent was somehow broken apart and its fragments — the continents of today — eventually drifted to their present location. The notion that continents can drift thousands of kilometers in a few hundred million years is now generally accepted, based on data from geology and geophysics. The large landmass of Pangaea became the two supercontinents of Laurasia and Gondwanaland; the landmasses were juxtaposed before the opening of either the Atlantic or the Indian Ocean. Based on studies of the relative motion of the landmasses involved, Fig. 2.1 presents a reconstruction of the dismemberment of the southern supercontinent of Gondwanaland, with diagrams showing the break up and subsequent dispersion of the continents over the past 180 million years: the Triassic, Jurassic, Cretaceous, and Cenozoic periods.
Ganpat Singh Roonwal
Chapter 3. Exploration Methods
Abstract
Coastal and offshore activities of both exploration and exploitation of the ocean resources are increasing rapidly all over the world. In the Indian Ocean region, similar activities have also been initiated and have increased many fold; according to Dr. R. Goodfellow, President of the Engineering Committee on Ocean Resources, “a greater use will be made of the oceans in the next 20 years of this century than has been made during the first 80 years. By the year 2200 A.D., more use will have been made of the oceans than was made from the time life first flapped ashore, up to the present day.” Most of the countries bordering on the Indian Ocean are developing nations. Global energy scarcity, exploding populations with the consequent problems of food and water supply and coming strategic and geopolitical patterns will necessitate the inclusion of ocean development programmes in economic planning.
Ganpat Singh Roonwal
Chapter 4. Placer Deposits
Abstract
Placers may be defined as surficial mineral deposits formed by the mechanical concentration of mineral particles from weathered debris. The mechanical agent is usually alluvial, but can also be marine, aeolian, lacustrine, and glacial, and the mineral is usually heavy metal, such as gold. They are thus the deposits of gravel, sand or similar material resulting from the crumbling and erosion of solid rocks containing valuable minerals that have been derived from rocks or veins. Griffith designated all such accumulations alluvial deposits and stated that they are known as placer deposits in the USA and Canada. In many European descriptions they are described as alluvial deposits.
Ganpat Singh Roonwal
Chapter 5. Phosphorite
Abstract
Phosphorite (phosphate) deposits are generally of marine origin except the Guano deposits of the Chile-Peru coast, and the magmatic phosphate deposits of the Kola Peninsula. Most of them were formed during the Upper Cretaceous and Tertiary periods, although Precambrian phosphorites are now reported from Australia, Brazil, and India. Such fossil-bearing phosphate deposits occur within the limitation of narrow sedimentation zones on the sea floor. Phosphate accumulations occur on the sea floor in the form of nodules (Fig. 5.1) and grains (sand) at several places in the sea accessible in 30–400 m water depth and in shelf areas where high nutrients are available in the deep seas. Compared ot the phosphate deposits on land, the marine deposits have a low P2O5 content. With the increasing price of phosphate in the world market, such as seen in 1974, it may seem economical for several countries to seek phosphate in the oceans.
Ganpat Singh Roonwal
Chapter 6. Ferromanganese Nodules and Encrustations
Abstract
The ferromanganese deposits occurring in the deep sea are authigenic mineral deposits of recent origin. They form due to diverse chemical reactions on the sea floor and may help to provide information on physical, chemical, and biological processes taking place in the ocean as a whole. Significant advances have been made during the past two decades in obtaining information on their geochemistry, modes of formation and the distribution especially of potential ore grade.
Ganpat Singh Roonwal
Chapter 7. Metalliferous Sediments and Hydrothermal Ores
Abstract
On land, stratiform deposits are the most important and largest source of ores. Most of them are considered to be submarine and exhalative in origin and their source is ascribed to volcanic activity in a marine environment. Deposits of this type are found in many areas from nearly all geological periods, and they are also found in the present marine environment.
Ganpat Singh Roonwal
Chapter 8. Subsurface Sea Bed Deposits: Petroleum and Natural Gas
Abstract
Subsurface deposits of the sea bed are those contained within the structures of consolidated sedimentary and basement rocks. Basing primarily on the method of their extraction, they can be divided into two groups: (1) petroleum, natural gas, and sulphur, which are extracted through holes drilled into the sea floor and (2) coal, iron ore, and vein deposits, which are extracted with conventional mining by driving shafts and drifts into the sea bed from adjacent land areas. In the present section, hydrocarbon (petroleum) occurrence in the marine beds of shallow water as well as in deep water is discussed.
Ganpat Singh Roonwal
Chapter 9. Other Deposits. Unconsolidated Organic and Inorganic Deposits
Abstract
The unconsolidated organic and inorganic surface sediments of the ocean floor include several known deposits which are potentially economical. The pelagic sediments of deep offshore waters are classified as red clays if their organic content is less than 30%, and as oozes if their organic content is more than 30%. Although uneconomical at present, these clays and oozes contain some useful constituents such as calcium carbonate (CaCO3), Al, Fe oxides, and Si oxides. They literally cover the ocean floor and are estimated to be in the order of thousands of billions of tons.
Ganpat Singh Roonwal
Chapter 10. Mining and Environment
Abstract
Offshore mining in coastal and shallow water areas for heavy mineral placers such as cassiterite has been in operation for a long time. Several factors must be considered in any offshore exploration mining venture. Some of these have been briefly mentioned in Chaps. 1 and 3. They include the nature of minerals, and the economic and legal considerations involved in their exploitation, location of extraction plants, marketing, and environmental aspects, as shown in Fig. 10.1.
Ganpat Singh Roonwal
Backmatter
Metadaten
Titel
The Indian Ocean: Exploitable Mineral and Petroleum Resources
verfasst von
Dr. Ganpat Singh Roonwal
Copyright-Jahr
1986
Verlag
Springer Berlin Heidelberg
Electronic ISBN
978-3-642-95501-3
Print ISBN
978-3-642-95503-7
DOI
https://doi.org/10.1007/978-3-642-95501-3