A review of asbestos resources
- Authors: Abbott, Paul
- Date: 1983
- Subjects: Asbestos Asbestos -- Geology Silicate minerals Mineralogy Chrysotile
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4910 , http://hdl.handle.net/10962/d1001570
- Full Text:
- Date Issued: 1983
- Authors: Abbott, Paul
- Date: 1983
- Subjects: Asbestos Asbestos -- Geology Silicate minerals Mineralogy Chrysotile
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4910 , http://hdl.handle.net/10962/d1001570
- Full Text:
- Date Issued: 1983
Economic geology of sulphide nickel deposits
- Authors: Harrison, P A
- Date: 1983
- Subjects: Nickel sulfide , Ore deposits , Geology, Economic , Silicate minerals , Geochemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5022 , http://hdl.handle.net/10962/d1006349
- Description: From Chapter 1: It has been a long standing belief that many nickel sulphide ores are derivatives of magmatic processes in ultramafic and mafic rocks, and that they segregate from these magmas as immiscible sulphide droplets which are then concentrated into an orebody by gravitational settling either during intrusion or extrusion, or during the early stages of crystallization of the magma (Naldrett, 1981). Some geologists however, have suggested alternative mechanisms to explain the concentration of nickeliferous sulphides in the mafic and ultramafic hosts. These include hydrothermal replacement (Fleet, 1977), exhalative volcanic processes (Lusk, 1976), or major metamorphic upgrading of low grade, initially magmatic deposits (Barrett et al., 1977). It is not the purpose of this study to verify or disprove these hypotheses, but in so far as the initial concentration of sulphides in most deposits is concerned, these effects are relatively unimportant (Naldrett, 1981). The nickel sulphide ores associated with these mafic and ultramafic host rocks, invariably consist of nickeliferous pyrrhotite as the dominant phase, together with lesser, but variable, amounts of magnetite, pentlandite, chalcopyrite, cubanite, and platinum group elements (Reynolds, 1982).
- Full Text:
- Date Issued: 1983
- Authors: Harrison, P A
- Date: 1983
- Subjects: Nickel sulfide , Ore deposits , Geology, Economic , Silicate minerals , Geochemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5022 , http://hdl.handle.net/10962/d1006349
- Description: From Chapter 1: It has been a long standing belief that many nickel sulphide ores are derivatives of magmatic processes in ultramafic and mafic rocks, and that they segregate from these magmas as immiscible sulphide droplets which are then concentrated into an orebody by gravitational settling either during intrusion or extrusion, or during the early stages of crystallization of the magma (Naldrett, 1981). Some geologists however, have suggested alternative mechanisms to explain the concentration of nickeliferous sulphides in the mafic and ultramafic hosts. These include hydrothermal replacement (Fleet, 1977), exhalative volcanic processes (Lusk, 1976), or major metamorphic upgrading of low grade, initially magmatic deposits (Barrett et al., 1977). It is not the purpose of this study to verify or disprove these hypotheses, but in so far as the initial concentration of sulphides in most deposits is concerned, these effects are relatively unimportant (Naldrett, 1981). The nickel sulphide ores associated with these mafic and ultramafic host rocks, invariably consist of nickeliferous pyrrhotite as the dominant phase, together with lesser, but variable, amounts of magnetite, pentlandite, chalcopyrite, cubanite, and platinum group elements (Reynolds, 1982).
- Full Text:
- Date Issued: 1983
Geochemical exploration in arid and semi-arid environments
- Authors: Van Berkel, Ferdinand
- Date: 1983 , 2013-04-02
- Subjects: Geochemical prospecting , Arid regions
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4920 , http://hdl.handle.net/10962/d1004389 , Geochemical prospecting , Arid regions
- Description: Anomalous element distributions within the regolith result from chemical adjustments of the earth's surface to prevailing climatic conditions. Because of the lack of moisture in the arid environment, chemical equilibrium related to paleoclimates is largely maintained. Mechanical or clastic dispersion dominates arid weathering and hence the exploration approach is largely dictated by the degree of preservation of the paleoregolith. Arid environment geochemists thus have to contend with surface materials ranging from laterite and calcrete in areas where the imprint of aridity is minimal, to more conventional sample media such as bedrock, stream sediment and lithic soils in actively dissecting areas. Extraction techniques are designed specifically to isolate clastic dispersion trains. Thick mantles of aeolian and water-borne overburden characterise desert lowlands and are a challenge to the exploration geochemist. Techniques showing the most promise in these areas include groundwater geochemistry, vapour geochemistry, surface microlayer geochemistry, geobotany and biogeochemistry which attempt to isolate gaseous and weak hydromorphic, ore-related trace-element dispersions. Termite mound sampling yields convincing results and appears to be an under-utilised geochemical approach. , KMBT_363 , Adobe Acrobat 9.53 Paper Capture Plug-in
- Full Text:
- Date Issued: 1983
- Authors: Van Berkel, Ferdinand
- Date: 1983 , 2013-04-02
- Subjects: Geochemical prospecting , Arid regions
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4920 , http://hdl.handle.net/10962/d1004389 , Geochemical prospecting , Arid regions
- Description: Anomalous element distributions within the regolith result from chemical adjustments of the earth's surface to prevailing climatic conditions. Because of the lack of moisture in the arid environment, chemical equilibrium related to paleoclimates is largely maintained. Mechanical or clastic dispersion dominates arid weathering and hence the exploration approach is largely dictated by the degree of preservation of the paleoregolith. Arid environment geochemists thus have to contend with surface materials ranging from laterite and calcrete in areas where the imprint of aridity is minimal, to more conventional sample media such as bedrock, stream sediment and lithic soils in actively dissecting areas. Extraction techniques are designed specifically to isolate clastic dispersion trains. Thick mantles of aeolian and water-borne overburden characterise desert lowlands and are a challenge to the exploration geochemist. Techniques showing the most promise in these areas include groundwater geochemistry, vapour geochemistry, surface microlayer geochemistry, geobotany and biogeochemistry which attempt to isolate gaseous and weak hydromorphic, ore-related trace-element dispersions. Termite mound sampling yields convincing results and appears to be an under-utilised geochemical approach. , KMBT_363 , Adobe Acrobat 9.53 Paper Capture Plug-in
- Full Text:
- Date Issued: 1983
Geology and mine planning
- Authors: Maturana-Bascope, M
- Date: 1983
- Subjects: Geology , Mining geology , Geology, Economics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5027 , http://hdl.handle.net/10962/d1006896
- Description: From introduction: This dissertation aims to review the main aspects involved in mine planning, in order to provide the geologists with the main criteria to obtain a preliminary estimate of the minability of an in situ orebody, and to make the geologists aware of the information they can contribute to the planning engineers. Furthermore, an understanding of the basic principles behind mine planning may help the exploration geologist to select more realistic targets of exploration.
- Full Text:
- Date Issued: 1983
- Authors: Maturana-Bascope, M
- Date: 1983
- Subjects: Geology , Mining geology , Geology, Economics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5027 , http://hdl.handle.net/10962/d1006896
- Description: From introduction: This dissertation aims to review the main aspects involved in mine planning, in order to provide the geologists with the main criteria to obtain a preliminary estimate of the minability of an in situ orebody, and to make the geologists aware of the information they can contribute to the planning engineers. Furthermore, an understanding of the basic principles behind mine planning may help the exploration geologist to select more realistic targets of exploration.
- Full Text:
- Date Issued: 1983
Geology of the central and southern domains of the Koras Group, northern Cape Province
- Sanderson-Damstra, Christopher Gerald
- Authors: Sanderson-Damstra, Christopher Gerald
- Date: 1983 , 2013-04-17
- Subjects: Geology -- South Africa -- Cape of Good Hope
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5017 , http://hdl.handle.net/10962/d1006203 , Geology -- South Africa -- Cape of Good Hope
- Description: The Central and Southern Domains of the Koras Group, situated on the Doornberg Lineament, are the structurally preserved remnants of a once more widespread late-syntectonic cover sequence. Detailed examination of the field relationships, lithology and petrography together with new geochemical data (30 analyses) has resulted in the proposal of a new geological succession consisting mainly of two cycles of bimodal basaltic-rhyolitic volcanics with interbedded, immature conglomerates and lithic greywackes. These two cycles, named the Boomrivier and Leeudraai Formations, are overlain by the immature, polymictic orthoconglomerates and red arkosic sandstones of the Kalkpunt Formation. The first volcanic cycle commenced with the Lambrechtsdrif basaltic andesites and was followed, after a short hiatus, by the Swartkopsleegte rhyodacites. The second cycle comprises the Rouxville basalts and basaltic andesites and the Swartkop and Kenilworth rhyolites. Field evidence suggests that eruption of the rhyolitic and basaltic volcanics in the second cycle was contemporaneous. Geochemically, the volcanics can be classified as an "average-K" to high-K, tholeiitic, subalkaline association which exhibits general similarities to other Southern African bimodal associations e.g., the tholeiitic lavas of the Wilgenhoutsdrif Group. The Koras Group is petrologically similar to the Sinclair Sequence which is presently considered to be its coeval equivalent, but the dominantly calc-alkaline character of the Sinclair rocks distinguishes them from the dominantly tholeiitic Koras lavas. In a short literature review, the four main hypotheses for the petrogenesis of bimodal associations: liquid immiscibility, crystal fractionation, two-stage partial melting and separate magma sources, are described and the most feasible explanation for the origin of the Koras lavas is thought to be a "separate magma source" hypothesis in which two cycles of mantle-derived basalts and crustal-derived rhyolites were produced in a zone of high heat flow and erupted in an area of crustal weakness. The middle- or late-Proterozoic Koras Group was formed during unstable tectonic conditions, in a depositional setting that was probably controlled by late folding of the underlying pre-Koras sequences as well as the major strike-slip movement and subordinate dip-slip faulting in the Doornberg Lineament.
- Full Text:
- Date Issued: 1983
- Authors: Sanderson-Damstra, Christopher Gerald
- Date: 1983 , 2013-04-17
- Subjects: Geology -- South Africa -- Cape of Good Hope
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5017 , http://hdl.handle.net/10962/d1006203 , Geology -- South Africa -- Cape of Good Hope
- Description: The Central and Southern Domains of the Koras Group, situated on the Doornberg Lineament, are the structurally preserved remnants of a once more widespread late-syntectonic cover sequence. Detailed examination of the field relationships, lithology and petrography together with new geochemical data (30 analyses) has resulted in the proposal of a new geological succession consisting mainly of two cycles of bimodal basaltic-rhyolitic volcanics with interbedded, immature conglomerates and lithic greywackes. These two cycles, named the Boomrivier and Leeudraai Formations, are overlain by the immature, polymictic orthoconglomerates and red arkosic sandstones of the Kalkpunt Formation. The first volcanic cycle commenced with the Lambrechtsdrif basaltic andesites and was followed, after a short hiatus, by the Swartkopsleegte rhyodacites. The second cycle comprises the Rouxville basalts and basaltic andesites and the Swartkop and Kenilworth rhyolites. Field evidence suggests that eruption of the rhyolitic and basaltic volcanics in the second cycle was contemporaneous. Geochemically, the volcanics can be classified as an "average-K" to high-K, tholeiitic, subalkaline association which exhibits general similarities to other Southern African bimodal associations e.g., the tholeiitic lavas of the Wilgenhoutsdrif Group. The Koras Group is petrologically similar to the Sinclair Sequence which is presently considered to be its coeval equivalent, but the dominantly calc-alkaline character of the Sinclair rocks distinguishes them from the dominantly tholeiitic Koras lavas. In a short literature review, the four main hypotheses for the petrogenesis of bimodal associations: liquid immiscibility, crystal fractionation, two-stage partial melting and separate magma sources, are described and the most feasible explanation for the origin of the Koras lavas is thought to be a "separate magma source" hypothesis in which two cycles of mantle-derived basalts and crustal-derived rhyolites were produced in a zone of high heat flow and erupted in an area of crustal weakness. The middle- or late-Proterozoic Koras Group was formed during unstable tectonic conditions, in a depositional setting that was probably controlled by late folding of the underlying pre-Koras sequences as well as the major strike-slip movement and subordinate dip-slip faulting in the Doornberg Lineament.
- Full Text:
- Date Issued: 1983
Metallogenetic evolution of the Canadian Cordilleran Orogen
- Authors: Mathe, H L M
- Date: 1983
- Subjects: Orogeny -- Canadian Cordillera , Plate tectonics -- Canadian Cordillera , Metallogeny -- Canadian Cordillera , Geology, Structural -- Canadian Cordillera
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5025 , http://hdl.handle.net/10962/d1006890
- Description: From Introduction: The Canadian Cordilleran Orogenic Belt forms part of the circum-Pacific orogenic zone. It underlies an area of about 1,54 million sq. kilometres, is over 2400 kilometres long and 800 kilometres wide. The region is characteristically mountainous, much of it glaciated and alpine, containing plateaux, trenches, valleys, and fjords. The mountains, in general, rise to elevations between 2100 m and 3600 m above sea level, although Mount Logan in the St. Elias Mountains attains an altitude of 6000 m. The Canadian Cordillera is divided into two dominant orogenic belts: the eastern Columbian Orogenic Belt comprising defonned miogeosynclinal rocks and the western Pacific Orogenic Belt comprising allochthonous eugeosynclinal rocks. The Cordillera is further subdivided into five longitudinal tectonic belts within which rocks are broadly similar in type, age, and history. These belts are, from east to west: the Rocky Mountain Belt, the Omineca Crystalline Belt, the Intermontane Belt, the Coast Plutonic Complex, and the Insular Belt (Wheeler et al., 1972a). The Canadian Cordillera is important in that it contains: one of the world's largest lead-zinc-silver mine, Sullivan; the second-largest molybdenum mine, Endako; one of the most important concentrations of porphyry copper deposits, Highland Valley; Canada's largest tungsten mines, Cantung and Mactung; and Canada's second-largest silver district, Keno Hill (Sutherland Brown et a1., 1971). In addition, it contains several large massive sulphide and lead-zinc deposits.
- Full Text:
- Date Issued: 1983
- Authors: Mathe, H L M
- Date: 1983
- Subjects: Orogeny -- Canadian Cordillera , Plate tectonics -- Canadian Cordillera , Metallogeny -- Canadian Cordillera , Geology, Structural -- Canadian Cordillera
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5025 , http://hdl.handle.net/10962/d1006890
- Description: From Introduction: The Canadian Cordilleran Orogenic Belt forms part of the circum-Pacific orogenic zone. It underlies an area of about 1,54 million sq. kilometres, is over 2400 kilometres long and 800 kilometres wide. The region is characteristically mountainous, much of it glaciated and alpine, containing plateaux, trenches, valleys, and fjords. The mountains, in general, rise to elevations between 2100 m and 3600 m above sea level, although Mount Logan in the St. Elias Mountains attains an altitude of 6000 m. The Canadian Cordillera is divided into two dominant orogenic belts: the eastern Columbian Orogenic Belt comprising defonned miogeosynclinal rocks and the western Pacific Orogenic Belt comprising allochthonous eugeosynclinal rocks. The Cordillera is further subdivided into five longitudinal tectonic belts within which rocks are broadly similar in type, age, and history. These belts are, from east to west: the Rocky Mountain Belt, the Omineca Crystalline Belt, the Intermontane Belt, the Coast Plutonic Complex, and the Insular Belt (Wheeler et al., 1972a). The Canadian Cordillera is important in that it contains: one of the world's largest lead-zinc-silver mine, Sullivan; the second-largest molybdenum mine, Endako; one of the most important concentrations of porphyry copper deposits, Highland Valley; Canada's largest tungsten mines, Cantung and Mactung; and Canada's second-largest silver district, Keno Hill (Sutherland Brown et a1., 1971). In addition, it contains several large massive sulphide and lead-zinc deposits.
- Full Text:
- Date Issued: 1983
Metallogenic evolution of the southern Appalachian Orogenic Belt and Mississippi Valley
- Authors: Maassen, Larry W
- Date: 1983 , 2013-04-03
- Subjects: Metallogeny -- Appalachian Region , Metallogeny -- Mississippi River Valley , Plate tectonics -- Appalachian Region , Plate tectonics -- Mississippi River Valley
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5018 , http://hdl.handle.net/10962/d1006210 , Metallogeny -- Appalachian Region , Metallogeny -- Mississippi River Valley , Plate tectonics -- Appalachian Region , Plate tectonics -- Mississippi River Valley
- Description: Plate tectonic theory provides logical explanations for the major tectonic events in the eastern US during Paleozoic time. The details of these tectonic events are becoming more apparent with the accumulation of new data, especially radiometric age dates. When plate tectonic theory is applied to specific tectonic events for which there is no substantial evidence, such as intracontinental hotspot rifting environments and Precambrian subduction zones, the proposed models may become very speculative. A misconception concerning the geology of the central US is that this region is structurally stable. However, geologists are currently paying considerable attention to the interlocking network of faults that in a general way follow the 38th parallel of latitude from west-central Virginia into Central Missouri (and may extend farther to the east and west). Most of the displacement along this zone occurred during the Precambrian, but different parts have moved during several periods of post-Precambrian time. In the basement the lineament may be a wide fracture zone that extends deep into the crust and is thus responsible for the magmatic iron deposits of the Southeast Missouri and may be either directly or indirectly responsible for the localization of the Mississippi Valley type deposits that occur sporadically along its length. Whether or not plate-tectonic processes operated during the Precambrian is open to speculation and the lineament may or may not be related to plate tectonic activity, but it is obvious that throughout time inherent zones of weakness are important in the localization of ore deposits. The occurrence of several major mineral districts at the intersections of the 38th parallel lineament with other major structural features, particularly in some uplifted areas and fault zone intersections, suggests that other similar structural uplifts and fault-zone intersections should be investigated for undiscovered new districts or extensions of known districts. Small uneconomic mineral occurrences along fault zones intersecting the lineament may merit further examination as they may be indications of undiscovered deposits at depth. The overall tectonic environment in the Appalachian region was an important control on the localization of massive sulfide, gold, titanium, and tungsten deposits. The deposits occur in clusters, either in Late Precambrian spreading centers and associated rift systems related to the breakup of proto-Pangea, or in Eocambrian and Devonian low-potassium tholeiitic volcanic and plutonic rocks associated with the volcanic island arc systems which developed during the closing of the Iapetus Ocean. Feiss and Hauck (1980) are confident that moderate sized (1-10 million ton) massive sulfide deposits are yet to be found at depth in these regions of the southern Appalachians, but large (greater than 20 million ton) massive sulfide deposits are unlikely to exist. The Mississippi Valley carbonate-hosted deposits of lead-zinc-baritefluorite, that occur to some extent throughout the Paleozoic section, and the Silurian "Clinton" iron ores owe their origin and distribution to normal sedimentary and diagenetic processes resulting from the transgressions of the epeiric seas. Others, such as the residual deposits of managnese iron, and aluminum, owe their existence to the afore mentioned processes, but must also have had subsequent exposure to the concentrating mechanism of weathering in a stable environment. The Mississippi Valley type occur primarily around paleo-basement highs and paleoshorelines; therefore, the formation of domes and arches within the continental interior during bathygenic episodes was a major factor controlling the localization of these deposits. These broad upwarps were preferential sites for reefal development and facies changes, and, during epeirogenic periods, these positive features have resulted in erosion and karsting of the the carbonate rocks by meteoric waters and have thus been prepared for mineralization. Deposits of this type are most common below a pre-Middle Ordovician unconformity and should be sought along major domes and arches, and along major lineaments. The association of Applachian type deposits with arches is indeterminate because a structure as subtle as an arch would be difficult to detect following overprinting by the deformation of the Alleghany orogeny; however, there is no reason to suspect that this type of positive feature did not play a role in their location. In conclusion, plate movements were a major control on the Paleozoic tectonic history of the eastern US and were also the primary control on the localization of the base metal, gold, tungsten, chromite, and titanium deposits of the southern Appalachians. However, important sedimentary and diagenetic deposits were localized primarily by arch, dome, and basin development during bathygenic episodes. Whether these submergent episodes are the result of plate motion or whether plate motion is indirectly related to submergent episodes, as suggested by Sloss and Speed (1974), remains a problem that needs to be investigated and debated further. , KMBT_363 , Adobe Acrobat 9.53 Paper Capture Plug-in
- Full Text:
- Date Issued: 1983
- Authors: Maassen, Larry W
- Date: 1983 , 2013-04-03
- Subjects: Metallogeny -- Appalachian Region , Metallogeny -- Mississippi River Valley , Plate tectonics -- Appalachian Region , Plate tectonics -- Mississippi River Valley
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5018 , http://hdl.handle.net/10962/d1006210 , Metallogeny -- Appalachian Region , Metallogeny -- Mississippi River Valley , Plate tectonics -- Appalachian Region , Plate tectonics -- Mississippi River Valley
- Description: Plate tectonic theory provides logical explanations for the major tectonic events in the eastern US during Paleozoic time. The details of these tectonic events are becoming more apparent with the accumulation of new data, especially radiometric age dates. When plate tectonic theory is applied to specific tectonic events for which there is no substantial evidence, such as intracontinental hotspot rifting environments and Precambrian subduction zones, the proposed models may become very speculative. A misconception concerning the geology of the central US is that this region is structurally stable. However, geologists are currently paying considerable attention to the interlocking network of faults that in a general way follow the 38th parallel of latitude from west-central Virginia into Central Missouri (and may extend farther to the east and west). Most of the displacement along this zone occurred during the Precambrian, but different parts have moved during several periods of post-Precambrian time. In the basement the lineament may be a wide fracture zone that extends deep into the crust and is thus responsible for the magmatic iron deposits of the Southeast Missouri and may be either directly or indirectly responsible for the localization of the Mississippi Valley type deposits that occur sporadically along its length. Whether or not plate-tectonic processes operated during the Precambrian is open to speculation and the lineament may or may not be related to plate tectonic activity, but it is obvious that throughout time inherent zones of weakness are important in the localization of ore deposits. The occurrence of several major mineral districts at the intersections of the 38th parallel lineament with other major structural features, particularly in some uplifted areas and fault zone intersections, suggests that other similar structural uplifts and fault-zone intersections should be investigated for undiscovered new districts or extensions of known districts. Small uneconomic mineral occurrences along fault zones intersecting the lineament may merit further examination as they may be indications of undiscovered deposits at depth. The overall tectonic environment in the Appalachian region was an important control on the localization of massive sulfide, gold, titanium, and tungsten deposits. The deposits occur in clusters, either in Late Precambrian spreading centers and associated rift systems related to the breakup of proto-Pangea, or in Eocambrian and Devonian low-potassium tholeiitic volcanic and plutonic rocks associated with the volcanic island arc systems which developed during the closing of the Iapetus Ocean. Feiss and Hauck (1980) are confident that moderate sized (1-10 million ton) massive sulfide deposits are yet to be found at depth in these regions of the southern Appalachians, but large (greater than 20 million ton) massive sulfide deposits are unlikely to exist. The Mississippi Valley carbonate-hosted deposits of lead-zinc-baritefluorite, that occur to some extent throughout the Paleozoic section, and the Silurian "Clinton" iron ores owe their origin and distribution to normal sedimentary and diagenetic processes resulting from the transgressions of the epeiric seas. Others, such as the residual deposits of managnese iron, and aluminum, owe their existence to the afore mentioned processes, but must also have had subsequent exposure to the concentrating mechanism of weathering in a stable environment. The Mississippi Valley type occur primarily around paleo-basement highs and paleoshorelines; therefore, the formation of domes and arches within the continental interior during bathygenic episodes was a major factor controlling the localization of these deposits. These broad upwarps were preferential sites for reefal development and facies changes, and, during epeirogenic periods, these positive features have resulted in erosion and karsting of the the carbonate rocks by meteoric waters and have thus been prepared for mineralization. Deposits of this type are most common below a pre-Middle Ordovician unconformity and should be sought along major domes and arches, and along major lineaments. The association of Applachian type deposits with arches is indeterminate because a structure as subtle as an arch would be difficult to detect following overprinting by the deformation of the Alleghany orogeny; however, there is no reason to suspect that this type of positive feature did not play a role in their location. In conclusion, plate movements were a major control on the Paleozoic tectonic history of the eastern US and were also the primary control on the localization of the base metal, gold, tungsten, chromite, and titanium deposits of the southern Appalachians. However, important sedimentary and diagenetic deposits were localized primarily by arch, dome, and basin development during bathygenic episodes. Whether these submergent episodes are the result of plate motion or whether plate motion is indirectly related to submergent episodes, as suggested by Sloss and Speed (1974), remains a problem that needs to be investigated and debated further. , KMBT_363 , Adobe Acrobat 9.53 Paper Capture Plug-in
- Full Text:
- Date Issued: 1983
The concept of grade in mineral deposits
- Authors: Esterhuizen, Anton G
- Date: 1983 , 2013-04-04
- Subjects: Mines and mineral resources , Ore deposits , Mineralogy , Geology, Economic
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5020 , http://hdl.handle.net/10962/d1006331 , Mines and mineral resources , Ore deposits , Mineralogy , Geology, Economic
- Description: The grade of a mineral deposit is determined by the effectiveness of a geological ore forming process, which is the result of the interaction between an ore forming mechanism and the environment in which it operates. Properties of a mineral deposit controlled by ore forming processes include the distribution, density and nature of ore minerals and gangue, and the metal content and impurities of the ore minerals. More efficient ore forming processes tend to develop in the larger mineralizing systems giving rise to richer deposits. As the geological environment within which a mineral deposit evolves becomes more complex a greater number of variables interact to determine the grade of the deposit. This is reflected in the greater variability of the grade distribution, resulting in greater difficulties in obtaining reliable estimates of the recoverable grade, and increased difficulties in the processing of ores. In response to economic fluctuations the working grade of heterogeneous orebodies, that form in geologically complex environments, can often be altered to ensure the continued viability of a mining venture. In contrast the evenly mineralized orebodies that tend to develop in geologically simple environments do not have this flexibility. All the important decisions in the mining industry, such as feasibility studies, choice of ~ining and processing methods, selection and planning, are made on the basis of, or are related to, grade estimates. If the geological controls of grade are fully understood, then it is possible to optimize the selection of the various mining alternatives, leading to the efficient exploitation of ore deposits.
- Full Text:
- Date Issued: 1983
- Authors: Esterhuizen, Anton G
- Date: 1983 , 2013-04-04
- Subjects: Mines and mineral resources , Ore deposits , Mineralogy , Geology, Economic
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5020 , http://hdl.handle.net/10962/d1006331 , Mines and mineral resources , Ore deposits , Mineralogy , Geology, Economic
- Description: The grade of a mineral deposit is determined by the effectiveness of a geological ore forming process, which is the result of the interaction between an ore forming mechanism and the environment in which it operates. Properties of a mineral deposit controlled by ore forming processes include the distribution, density and nature of ore minerals and gangue, and the metal content and impurities of the ore minerals. More efficient ore forming processes tend to develop in the larger mineralizing systems giving rise to richer deposits. As the geological environment within which a mineral deposit evolves becomes more complex a greater number of variables interact to determine the grade of the deposit. This is reflected in the greater variability of the grade distribution, resulting in greater difficulties in obtaining reliable estimates of the recoverable grade, and increased difficulties in the processing of ores. In response to economic fluctuations the working grade of heterogeneous orebodies, that form in geologically complex environments, can often be altered to ensure the continued viability of a mining venture. In contrast the evenly mineralized orebodies that tend to develop in geologically simple environments do not have this flexibility. All the important decisions in the mining industry, such as feasibility studies, choice of ~ining and processing methods, selection and planning, are made on the basis of, or are related to, grade estimates. If the geological controls of grade are fully understood, then it is possible to optimize the selection of the various mining alternatives, leading to the efficient exploitation of ore deposits.
- Full Text:
- Date Issued: 1983
The geological evolution and mineralised environments of the Tasman Geosyncline
- Authors: Pelham, D A
- Date: 1983 , 2013-04-03
- Subjects: Geosynclines -- Tasmania , Geology -- Tasmania , Ore deposits -- Tasmania , Mineralogy -- Tasmania
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5030 , http://hdl.handle.net/10962/d1006936 , Geosynclines -- Tasmania , Geology -- Tasmania , Ore deposits -- Tasmania , Mineralogy -- Tasmania
- Description: From introduction: The Tasman Geosyncline covers the eastern part of the continent of Australia, an area of over 2 million km'. The area has been a major source of Australian gold and tin production, and though it contains important base metal sulphide deposits, these are overshadowed in scale by the very large stratabound Proterozoic deposits (for example, Mt Isa, Broken Hill and McArthur River). This dissertation deals with the metallic mineral deposits of the Tasman Geosyncline, and as such does not include the extensive post Palaeozoic continental successions, with their important coal reserves, that overlie the deformed geosyncl i nal sequences.
- Full Text:
- Date Issued: 1983
- Authors: Pelham, D A
- Date: 1983 , 2013-04-03
- Subjects: Geosynclines -- Tasmania , Geology -- Tasmania , Ore deposits -- Tasmania , Mineralogy -- Tasmania
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5030 , http://hdl.handle.net/10962/d1006936 , Geosynclines -- Tasmania , Geology -- Tasmania , Ore deposits -- Tasmania , Mineralogy -- Tasmania
- Description: From introduction: The Tasman Geosyncline covers the eastern part of the continent of Australia, an area of over 2 million km'. The area has been a major source of Australian gold and tin production, and though it contains important base metal sulphide deposits, these are overshadowed in scale by the very large stratabound Proterozoic deposits (for example, Mt Isa, Broken Hill and McArthur River). This dissertation deals with the metallic mineral deposits of the Tasman Geosyncline, and as such does not include the extensive post Palaeozoic continental successions, with their important coal reserves, that overlie the deformed geosyncl i nal sequences.
- Full Text:
- Date Issued: 1983
The significance of unconformities in the development of Witwatersrand gold and uranium placers
- Authors: Beater, Christian Douglas
- Date: 1983 , 2013-04-03
- Subjects: Placer deposits , Gold ores -- Geology -- South Africa -- Witwatersrand , Uranium ores -- Geology -- South Africa -- Witwatersrand
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4925 , http://hdl.handle.net/10962/d1004535 , Placer deposits , Gold ores -- Geology -- South Africa -- Witwatersrand , Uranium ores -- Geology -- South Africa -- Witwatersrand
- Description: Most of the economic gold and uranium placers are developed on low angle disconformities in the Central Rand Group and concentrations of gold and uranium are usually at their optimum on unconformity surfaces. Examples include the Kimberley Reef and South Reef of the East Rand, the Main Reef Leader of the Central Rand, the Carbon Leader of the Carletonville goldfield, the Vaal Reef of the Klerksdorp goldfield and the Basal/Steyn placers of the Welkom goldfield. The individual goldfields represent fluvial fans which are composed of a large number of tectonogenetic sedimentary packages separated by unconformities. The tectonic responses between cycles of sedimentation produced unconformities and tectonically controlled cyclic sedimentation is one of the key factors culminating in the preparation and deposition of auriferous placers within the Witwatersrand succession. Unconformities, which represent breaks in sedimentation, result in the preconditioning of palaeosurfaces and redistribution of sediments and heavy minerals on them. Winnowing of sands produced heavy mineral residual accumulations on erosion surfaces which were generally preserved by small-pebble lags or algal mats. Reworking of units truncated by the unconformities provided additional gold, uranium and heavy minerals to unconformity surfaces.
- Full Text:
- Date Issued: 1983
- Authors: Beater, Christian Douglas
- Date: 1983 , 2013-04-03
- Subjects: Placer deposits , Gold ores -- Geology -- South Africa -- Witwatersrand , Uranium ores -- Geology -- South Africa -- Witwatersrand
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4925 , http://hdl.handle.net/10962/d1004535 , Placer deposits , Gold ores -- Geology -- South Africa -- Witwatersrand , Uranium ores -- Geology -- South Africa -- Witwatersrand
- Description: Most of the economic gold and uranium placers are developed on low angle disconformities in the Central Rand Group and concentrations of gold and uranium are usually at their optimum on unconformity surfaces. Examples include the Kimberley Reef and South Reef of the East Rand, the Main Reef Leader of the Central Rand, the Carbon Leader of the Carletonville goldfield, the Vaal Reef of the Klerksdorp goldfield and the Basal/Steyn placers of the Welkom goldfield. The individual goldfields represent fluvial fans which are composed of a large number of tectonogenetic sedimentary packages separated by unconformities. The tectonic responses between cycles of sedimentation produced unconformities and tectonically controlled cyclic sedimentation is one of the key factors culminating in the preparation and deposition of auriferous placers within the Witwatersrand succession. Unconformities, which represent breaks in sedimentation, result in the preconditioning of palaeosurfaces and redistribution of sediments and heavy minerals on them. Winnowing of sands produced heavy mineral residual accumulations on erosion surfaces which were generally preserved by small-pebble lags or algal mats. Reworking of units truncated by the unconformities provided additional gold, uranium and heavy minerals to unconformity surfaces.
- Full Text:
- Date Issued: 1983
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