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Indian Ocean
Sandstone is the most significant rock type in the Natal Group, and extends widely within the Marianhill Formation. Due to its prevalence within the Natal Basin it is widely used as aggregate material. It is therefore important to study the physical properties and their relationship to the mechanical properties. The literature on this topic is rather limited. This study constitutes an investigation of the published data, and the application of self-organizing maps (SOMs) and data-mining techniques to extract new knowledge and yield further insight into the relationships between the petrographic, physical, and mechanical characteristics of sandstone. SOM-based analysis distinguished three clusters of sandstones, based on petrographic, physical, and geotechnical characteristics, which led to the identification of different lithofacies. Significant parameters dictating cluster identification are the type of grain contact, void space, packing density, and amount of silica cement. INTRODUCTION The sandstones studied fall under the Natal Group, which is a succession of reddish-grey sandstones with subordinate siltstones, shales, and conglomerates, regarded as a molasse deposit that accumulated 490 Ma ago (Thomas et al., 1992). The great majority of the sediments of the Natal Group were deposited in a fluvial environment and represent a terrestrial succession, interrupted by occasional shallow marine transgressions during which quartz arenites were deposited, Marshall (1994). The thickness of the Group ranges from 45 to 600 m, of which the Newspaper Member comprises some 80%. Marshal (1994), recognized two formations within the Natal Group, the lower Durban Formation and the upper Marianhill Formation, which is subdivided into three members; from oldest to youngest the Tullini, Newspaper, and Westville members. The Newspaper Member comprises 90% of the Marianhill Formation and occurs over the whole of the Natal Group basin. The most important sedimentary feature is the planar cross-bedding.
- Africa > South Africa > Indian Ocean (0.24)
- Africa > Mozambique > Indian Ocean (0.24)
- Africa > Madagascar > Indian Ocean (0.24)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (1.00)
- Geology > Geological Subdiscipline (1.00)
- Africa > South Africa > Indian Ocean > Natal Basin (0.99)
- Africa > Mozambique > Indian Ocean > Natal Basin (0.99)
- Africa > Madagascar > Indian Ocean > Natal Basin (0.99)
Abstract This paper deals with the environmental problems related to Petroleum Exploration Programs (P E P) in Madagascar and measures taken, in short terms, to minimize environment degradation resulting from these. PEP concerns the three main western sedimentary PEP concerns the three main western sedimentary basins (Ambilobe Basin - Majunga Basin - Morondava basin) -Fig. 2- of which 12% of the surface are classified as "protected area" (forests, parks, reserves) in respect of the richness and rareness of wildlife species. PEP's operations (seismic survey and drilling PEP's operations (seismic survey and drilling wells), when conducted in these zones, affect the system (access road, people migration), leading to the degradation of the wildlife. For petroleum companies working in those zones, some appropriate measures (adequacy of equipment, engagement to restore damages, environment study) were required before concerned administration could grant the agreement. One example of specific environment damages caused by Petroleum Exploration Operations is mentioned in this paper. Introduction As specimen rare in the world, Madagascar's wildlife species are protected by the 1933 London Convention on International Trade in Endangered species of wild Fauna and Flora. And in general, major dispositions were considered to preserve and safeguard the environmental aspect. In the other side, since the beginning of the century, in order to solve the urge needs for energy self sufficiency, the development of petroleum research through intensive activities came to be the highest priority for the country. Derogations were delivered, which sometimes by-passed the law in force, related to the environmental policy. During the last decade, the reality is so that damages become more and more serious. This situation is illustrated by the degradation of the environment as well as the threat of extinction of rare wildlifes and flora. However, since these last 5 years, with technical and financial assistance of various international organizations, special and intensive care, as well as concrete programs, were applied in environmental matter to limit the damage and to reinstate the patrimony. In particular, being aware of the real danger, OMNIS (OFFICE MILITAIRE NATIONAL POUR LES INDUSTRIES STRATEGIQUES), the own-state organization in charge of coordination for all exploration activities in Madagascar, with collaboration of petroleum companies holding concessions, has considered various dispositions in order to establish a better compromise between the "environmental" entity and the exploration activities as a sector of "economic development". ENVIRONMENT IN MADAGASCAR Malagasy vegetation is distributed within two distinct biogeographic regions, where the vegetation composition is well defined and differentiated For fauna, these two regions do not constitute well pronounced limit. P. 265
- Africa > Madagascar > Menabe > Morondava (0.25)
- Africa > Madagascar > Indian Ocean > Mozambique Channel (0.24)
- Africa > Madagascar > Indian Ocean > Mozambique Channel > Majunga Basin (0.99)
- North America > United States > Gulf of Mexico > Central GOM > East Gulf Coast Tertiary Basin > De Soto Canyon > Block 757 > Madagascar Field > Norphlet Formation (0.95)
- Management > Strategic Planning and Management > Exploration and appraisal strategies (1.00)
- Health, Safety, Environment & Sustainability > Environment (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (0.89)
- Health, Safety, Environment & Sustainability > HSSE & Social Responsibility Management (0.88)
ABSTRACT Three multichannel seismic surveys were carried out by the French CEPM Group (Comité d'études Pétrolierès et Marines) and the IPGP (Institut de Physique du Globe de Paris) on the continental margins of the South-Western Indian Ocean. The surveys seismic sources were the Flexotir or the Flexichoc from IFP (Institut Français du pétrole). The data collected on these cruises have given a lot of new results about the structure and origin of the Mozambique Channel. The general morphological features of this area have been confirmed:The South-Western Somali basin. The deep Mozambique and Natal basins (4 500 to 5 000 m depth). The basins are bounded on the West by the Mozambique Ridge and the Beira horst and on-the East by a roughly North-South trending feature: the DAVIE Ridge. This ridge divides in fact the Mozambique Channel in two different basins : the deep Mozambique basin on the West and Western Marginal Plateau of Madagascar on the East. The new magnetic data collected on these surveys have shown the extension of oceanic crust to the North till South-East of Beira horst, with probably Jurassic anomalies of about 150 MY BP. Seismic reflexion and refraction surveys have shown an increasing of visible sediment thickness from South to North (2 sec. to 4 sec. two-way time) in the deep Mozambique Channel. The delimitation of Oceanic and Continental areas in the South-Western Somali basin and Mozambique Channel has been attempted. In conclusion position of Madagascar relative to African Mainland will be discussed. INTRODUCTION This note is intended to present the results obtained during three geophysical surveys carried out by CEPM and IPGP, and to discuss the knowledge gained by processing of these data, concerning the structure and geological history on the South-Western margin of the Indian Ocean. CEPM (Comité d'Etudes Pétrolières et Marines) is a French group made up of the oil exploration companies Elf-Aquitaine, CFP-Total and the Institut Français du pétrole. The Laboratoire de Géophysique Marine of IPGP (Institut de Physique du Globe de Paris) directed by R. Schlich was joint surveyor during these operations. GEOGRAPHICAL FRAMEWORK From North to South, the survey zone includes (Figure 2):the South-Western Somali basin, the Mozambique channel, the Natal basin (hitherto called the Mozambique basin or the Madagascar basin). The South-Western Somali basin is bounded on the West by the African coast (Tanzania, Kenya) and on the East by the structural axis of the Amirante. On the South, the boundary with the Mozambique channel is materialized by the volcanic archipelago of the Comores. The Mozambique channel lying between the island of Madagascar on the East and the coast of Mozambique on the African mainland to the West is approximately 400 to 900 km wide.
- Africa > Middle East > Somalia > Indian Ocean (0.88)
- Africa > Madagascar > Indian Ocean (0.76)
- Africa > South Africa > Indian Ocean (0.46)
- Africa > Mozambique > Indian Ocean (0.46)
- Phanerozoic > Mesozoic > Jurassic (0.49)
- Phanerozoic > Cenozoic > Paleogene (0.47)
- Phanerozoic > Mesozoic > Cretaceous (0.32)
- North America > United States > Nevada > Eocene Basin (0.99)
- Africa > Mozambique > Mozambique Basin (0.99)
- Africa > Middle East > Somalia > Indian Ocean > Somali Basin (0.99)
- (5 more...)