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H. Beiersdorf; H.-R. Kudrass; Ulrich von Stackelberg:

Placer Deposits of limenite and Zircon on the Zambezi Shelf

1980. 85 pages, 32 figures, 4 tables, 6 plates, 17x24cm, 210 g
Language: English

(Geologisches Jahrbuch Reihe D, Band D 36)

ISBN 978-3-510-96156-6, paperback, price: 22.00 €

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Contents

Contents top ↑


1. Introduction 8
2. Geological framework 8
2.1. General outline 8
2.2. Quaternary geology in the coastal region 10
2.2.1. Pleistocene 11
2.2.2. Holocene 11
2.3. Heavy-mineral provenance and assemblages 12
2.4. Beach and dune placer deposits 12
3. Methods 13
3.1. Navigation 13
3.2. Echosounding 13
3.3. Geophysical methods 13
3.3.1. Refraction and reflection seismic measurements 13
3.3.2. Magnetometric and scintillometric measurements 15
3.4. Sedimentological methods 15
3.4.1. Sampling 15
3.4.2. Analysis of samples on board 15
3.4.3. Analysis of samples in the laboratories on shore 17
3.4.3.1. Identification of heavy minerals 17
3.4.3.2. Extraction of valuable heavy minerals 18
3.4.3.3. Other analyses 18
3.4.3.4. Data processing 19
3.5. Statistics 19
4. Results 21
4.1. Bathymetry and morphology 21
4.1.1. Bathymetric profiles 21
4.1.2. Terraces 21
4.1.3. Underwater sand dunes and ripples 23
4.1.4. Erosional furrows 23
4.1.5. Morphology and sediment transport 23
4.2. Geophysics 26
4.2.1. Refraction seismic data 26
4.2.2. Reflection seismic data 26
4.2.3. Acoustical characteristics of the uppermost sediments 28
4.3. Sedimentology of the surface sediments 29
4.3.1. Grain-size distribution 29
4.3.2. Composition 32
4.4. Shelf sediment sequences and their regional distribution
(sediment cores) 43
4.5. 14C-age determinations and sea-level history 47
4.6. Location, composition, and size of the heavy-mineral deposits 47
4.6.1. Heavy-mineral concentrations in the surface samples 49
4.6.2. Heavy-mineral concentrations in the core samples 49
4.6.3. Estimation of the heavy-mineral potential 52
4.6.4. Grain-size distribution of the heavy minerals 54
4.6.5. Chemical composition of ilmenite, rutile, and zircon 56
4.6.6. Economic aspects 57
4.7. Origin of the shelf sediments and of the disseminated placer deposits 57
4.7.1. Source rocks 57
4.7.2. Origin of heavy-mineral provinces 59
4.7.2.1. Opaque Province 62
4.7.2.2. Amphibole Province 64
4.7.2.3. Amphibole-Sillimanite Province and Epidote-Sillimanite Province 64
4.7.3. Depositional history of the disseminated placer deposits and shelf
sediments 65
5. References 69