Geodynamics, rifting, stratiform and stratabound mineral deposits
- Authors: Dingemans, D.R.W.
- Date: 1981 , 2013-03-19
- Subjects: Ore deposits , Geodynamics , Mines and mineral resources , Rifts (Geology)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5012 , http://hdl.handle.net/10962/d1006107 , Ore deposits , Geodynamics , Mines and mineral resources , Rifts (Geology)
- Description: Stratiform and stratabound ore deposits commonly show a direct relationship with rifts. This association is studied by developing a geodynamic model of mantle processes and crustal responses. The geodynamics of the earth can be modelled by the process of mantle advection, which involves the episodic generation and segregation of low density mantle diapirs and their rise and subsequent interaction with the crust. The theory of mantle advection explains the genetic association between rifting, magmatism, basin development and subsequent orogeny and metamorphism. Global evolution has passed through a number of major stages of non-uniformitarian development in which each cycle was characterized by fairly uniform behaviour terminated by intense geodynamic upheaval. The relationship between geological evolution and mantle advection is examined by reviewing the major characteristics of each of the cycles, which correspond to the Archean, Early Proterozoic, Mid Proterozoic, Late Proterozoic-Palaeo2oic, and Mesozoic - Cainozoic eras. Although mentle advection has controlled crustal processes throughout time, the decrease in the thermal energy of the earth has caused >the major evolutionary changes in response to thickening and a greater rigidity of the sialic crust. Rifts are penetrative taphrogenic faults in the earths crust which act as major conduits for the transfer of magmas, from the mantle and lower crustal levels, to the upper crust and the surface. Rifts are also permeable zones for the migration of metalliferous brines, generated by magmatic differentiation. These metalliferous brines would either be exhaled at surface to form stratiform volcanogenic and volcanosedimentary ore deposits , or would interact with preferential host horizons to form stratabound ore deposits . The associat ion between rifting and stratiform and stratabound ore deposits is illustrated by examining :he tectonic setting, and st ratigraphic relationships of typical ore deposit types .
- Full Text:
- Date Issued: 1981
- Authors: Dingemans, D.R.W.
- Date: 1981 , 2013-03-19
- Subjects: Ore deposits , Geodynamics , Mines and mineral resources , Rifts (Geology)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5012 , http://hdl.handle.net/10962/d1006107 , Ore deposits , Geodynamics , Mines and mineral resources , Rifts (Geology)
- Description: Stratiform and stratabound ore deposits commonly show a direct relationship with rifts. This association is studied by developing a geodynamic model of mantle processes and crustal responses. The geodynamics of the earth can be modelled by the process of mantle advection, which involves the episodic generation and segregation of low density mantle diapirs and their rise and subsequent interaction with the crust. The theory of mantle advection explains the genetic association between rifting, magmatism, basin development and subsequent orogeny and metamorphism. Global evolution has passed through a number of major stages of non-uniformitarian development in which each cycle was characterized by fairly uniform behaviour terminated by intense geodynamic upheaval. The relationship between geological evolution and mantle advection is examined by reviewing the major characteristics of each of the cycles, which correspond to the Archean, Early Proterozoic, Mid Proterozoic, Late Proterozoic-Palaeo2oic, and Mesozoic - Cainozoic eras. Although mentle advection has controlled crustal processes throughout time, the decrease in the thermal energy of the earth has caused >the major evolutionary changes in response to thickening and a greater rigidity of the sialic crust. Rifts are penetrative taphrogenic faults in the earths crust which act as major conduits for the transfer of magmas, from the mantle and lower crustal levels, to the upper crust and the surface. Rifts are also permeable zones for the migration of metalliferous brines, generated by magmatic differentiation. These metalliferous brines would either be exhaled at surface to form stratiform volcanogenic and volcanosedimentary ore deposits , or would interact with preferential host horizons to form stratabound ore deposits . The associat ion between rifting and stratiform and stratabound ore deposits is illustrated by examining :he tectonic setting, and st ratigraphic relationships of typical ore deposit types .
- Full Text:
- Date Issued: 1981
Geological factors affecting the grade and tonnage of sandstone uranium deposits
- Authors: Holliman, K A
- Date: 1981 , 2013-03-19
- Subjects: Uranium ores , Sandstone , Geology, Economic
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5009 , http://hdl.handle.net/10962/d1005914 , Uranium ores , Sandstone , Geology, Economic
- Description: The largest known reserves of uranium are found in sandstone deposits, in the form of roll-front, peneconcordant and stacked types. Drilling on spacings of between 50 m and 5 m centres is the current method of attempting to delineate such ore bodies but because of the apparent random distribution of the mineralization there is a large degree of uncertainty in these predictions. Even on drilling grids of 3,5 m centres the uncertainty in predicting the distribution of stringer ore in roll front mineralization is still 100 per cent. (Sandefur & Grant 1980). Because of escalating costs it is becoming increasingly less economically feasible to delineate bodies of this nature in this manner and much more reliance will have to be placed on the geologist's interpretation of ore distribution when calculating ore reserves. The grade and tonnage of a sandstone uranium deposit can only be calculated with some degree of confidence if the processes forming the ore body are fully understood. The aim of this review is to examine the factors governing the formation and geometry of a sandstone body, the mobility and fixation of uranium and to establish criteria which will enable a more confident prediction to be made of the distribution of sand bodies and the distribution of the mineralization within them
- Full Text:
- Date Issued: 1981
- Authors: Holliman, K A
- Date: 1981 , 2013-03-19
- Subjects: Uranium ores , Sandstone , Geology, Economic
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5009 , http://hdl.handle.net/10962/d1005914 , Uranium ores , Sandstone , Geology, Economic
- Description: The largest known reserves of uranium are found in sandstone deposits, in the form of roll-front, peneconcordant and stacked types. Drilling on spacings of between 50 m and 5 m centres is the current method of attempting to delineate such ore bodies but because of the apparent random distribution of the mineralization there is a large degree of uncertainty in these predictions. Even on drilling grids of 3,5 m centres the uncertainty in predicting the distribution of stringer ore in roll front mineralization is still 100 per cent. (Sandefur & Grant 1980). Because of escalating costs it is becoming increasingly less economically feasible to delineate bodies of this nature in this manner and much more reliance will have to be placed on the geologist's interpretation of ore distribution when calculating ore reserves. The grade and tonnage of a sandstone uranium deposit can only be calculated with some degree of confidence if the processes forming the ore body are fully understood. The aim of this review is to examine the factors governing the formation and geometry of a sandstone body, the mobility and fixation of uranium and to establish criteria which will enable a more confident prediction to be made of the distribution of sand bodies and the distribution of the mineralization within them
- Full Text:
- Date Issued: 1981
Geological factors affecting tonnage-grade relationships in orebodies of the Zambian Copperbelt
- Authors: McCulloch, Alan B
- Date: 1981
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:21151 , http://hdl.handle.net/10962/6617
- Description: The occurrence of a major metalliferous province in Zambia and Zaire is a reflection of geological processes operating in a specific environment during a particular period. The size of orebodies, their grade, mineralogy, beneficiation characteristics and therefore the amount of metal produced are all ultimately functions of the geology of the ores. This study is primarily concerned with the effect geology has on tonnage-grade relationships of ore in situ on the Zambian Copperbelt. Five major topics related to ore tonnage and grade are reviewed here: -behaviour of copper and cobalt in surficial environments. -geological setting and gross lithostratigraphic relationships of mineralization. -characteristics of known orebodies. -geological factors affecting mining and beneficiation of ore. -orebody limits and estimation of tonnage and grade. In addition, the historical background to the problems discussed here is briefly described, and some general aspects of the evaluation, mining and beneficiation of Copperbelt ores are considered in relation to metal production.
- Full Text:
- Date Issued: 1981
- Authors: McCulloch, Alan B
- Date: 1981
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:21151 , http://hdl.handle.net/10962/6617
- Description: The occurrence of a major metalliferous province in Zambia and Zaire is a reflection of geological processes operating in a specific environment during a particular period. The size of orebodies, their grade, mineralogy, beneficiation characteristics and therefore the amount of metal produced are all ultimately functions of the geology of the ores. This study is primarily concerned with the effect geology has on tonnage-grade relationships of ore in situ on the Zambian Copperbelt. Five major topics related to ore tonnage and grade are reviewed here: -behaviour of copper and cobalt in surficial environments. -geological setting and gross lithostratigraphic relationships of mineralization. -characteristics of known orebodies. -geological factors affecting mining and beneficiation of ore. -orebody limits and estimation of tonnage and grade. In addition, the historical background to the problems discussed here is briefly described, and some general aspects of the evaluation, mining and beneficiation of Copperbelt ores are considered in relation to metal production.
- Full Text:
- Date Issued: 1981
Geological factors that influence the evaluation and exploitation of Canadian copper-zinc massive sulphide-, and Japanese polymetallic (kuroko) deposits
- Authors: Venter, D M
- Date: 1981
- Subjects: Sulfides -- Canada , Ore deposits -- Japan
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4918 , http://hdl.handle.net/10962/d1003812
- Description: Volcanogenic massive sulphide deposits are important sources of base metals throughout the world. The Canadian Cu-Zn-(Au, Ag) deposits of Archaean age occur in greenstone terrains within the Canadian Shield. These deposits are closely associated with volcanic vents developed along zones of rifting within mobile belts. The vents are manifested by coarse felsic pyroclastics and/or rhyolitic domes. The Japanese Pb-Zn-Cu-Ba(Ag) deposits, generally known as Kuroko deposits, are of Miocene age, and although also associated with volcanic vents, are developed above zones of subduction. Mineralization in volcanogenic deposits is a result of submarine exhalation of metalliferous hydrothermal solutions derived from fractionation of predominantly calc-alkaline magmas. The deposits are characterized by certain geological features that result from the interaction of specific physical and chemical conditions during deposition. Primary features include massive and stringer sulphide bodies, alteration zones, mineralogical and metal zoning, and certain depositional textures and structures. These features are commonly modified by subsequent metamorphism and deformation which impart secondary ore textures and affect metal distribution and shape. The disparity in age between Canadian and Japanese deposits allows the entire spectrum of geological features to be studied; from the completely unaltered to the high deformed and recrystallized. The characteristic geological features are the prime factors which control the metal distribution and concentration, and the size and shape of the deposits, thereby influencing the viability of the respective ore bodies. A knowledge of these factors and the physico-chemical parameters which control them are thus fundamental in the "understanding" of these deposits. They ultimately control the geological interpretations and predictions made during ore body delineation, ore reserve estimation, mining and ore beneficiation.
- Full Text:
- Date Issued: 1981
- Authors: Venter, D M
- Date: 1981
- Subjects: Sulfides -- Canada , Ore deposits -- Japan
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4918 , http://hdl.handle.net/10962/d1003812
- Description: Volcanogenic massive sulphide deposits are important sources of base metals throughout the world. The Canadian Cu-Zn-(Au, Ag) deposits of Archaean age occur in greenstone terrains within the Canadian Shield. These deposits are closely associated with volcanic vents developed along zones of rifting within mobile belts. The vents are manifested by coarse felsic pyroclastics and/or rhyolitic domes. The Japanese Pb-Zn-Cu-Ba(Ag) deposits, generally known as Kuroko deposits, are of Miocene age, and although also associated with volcanic vents, are developed above zones of subduction. Mineralization in volcanogenic deposits is a result of submarine exhalation of metalliferous hydrothermal solutions derived from fractionation of predominantly calc-alkaline magmas. The deposits are characterized by certain geological features that result from the interaction of specific physical and chemical conditions during deposition. Primary features include massive and stringer sulphide bodies, alteration zones, mineralogical and metal zoning, and certain depositional textures and structures. These features are commonly modified by subsequent metamorphism and deformation which impart secondary ore textures and affect metal distribution and shape. The disparity in age between Canadian and Japanese deposits allows the entire spectrum of geological features to be studied; from the completely unaltered to the high deformed and recrystallized. The characteristic geological features are the prime factors which control the metal distribution and concentration, and the size and shape of the deposits, thereby influencing the viability of the respective ore bodies. A knowledge of these factors and the physico-chemical parameters which control them are thus fundamental in the "understanding" of these deposits. They ultimately control the geological interpretations and predictions made during ore body delineation, ore reserve estimation, mining and ore beneficiation.
- Full Text:
- Date Issued: 1981
Geology and ore reserve estimation of the Witwatersrand-type gold deposits with specific reference to the Welkom Goldfield
- Authors: Ainslie, L C
- Date: 1981
- Subjects: Mines and mineral resources -- Statistical methods Mine valuation -- Statistical methods Gold ores -- Geology Witwatersrand Basin (South Africa) Ores -- Sampling and estimation -- Statistical methods
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4911 , http://hdl.handle.net/10962/d1001571
- Full Text:
- Date Issued: 1981
- Authors: Ainslie, L C
- Date: 1981
- Subjects: Mines and mineral resources -- Statistical methods Mine valuation -- Statistical methods Gold ores -- Geology Witwatersrand Basin (South Africa) Ores -- Sampling and estimation -- Statistical methods
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4911 , http://hdl.handle.net/10962/d1001571
- Full Text:
- Date Issued: 1981
Hugo Raes : de roman als montage : een struktuuranalyse van De vadsige koningen, Een faun met kille horentjes en, Het smarán, het vikka, de ronko en al de andere kleuren van de geschiedenis
- Authors: Renders, L E M M E
- Date: 1981
- Subjects: Raes, Hugo -- Criticism and interpretation Raes, Hugo -- De vadsige koningen Raes, Hugo -- Een faun met kille horentjes Raes, Hugo -- Het smarán, het vikka, de ronko en al de andere kleuren van de geschiedenis Dutch fiction -- 20th century -- History and criticism
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3623 , http://hdl.handle.net/10962/d1007493
- Description: De analyse van het individuele literaire werk zal steeds het begin- en eindpunt moeten zijn van de literatuurstudie in welke gedaante dan ook: "Dit neemt echter niet weg dat het begin en einde, het alfa en omega van de literaire bedrijvigheid, het literair kunstwerk als zodanig, de literaire intentie, functie en efficientie de literair, literairesthetisch, te actualiseren en te valoriseren tekst is ... " (Rutten, 1973, p.144). Juist deze vorm van onderzoek lijkt op het ogenblik soms weI eens verloren te raken tussen de veelheid van literaire theorieen die overal opgang maken. De beoefenaars van de literaire kritiek lijken dikwijls meer begaan met het opbouwen en afbreken van theorieen dan met het literaire werk zelf. Sinds W. Bloks studie Verhaal en lezer in 1960 voor het eerst het licht zag, mag er dan op het gebied van de literatuurwetenschap in de Nederlanden en daarbuiten heel wat veranderd zijn, maar zijn uitspraak: " ... dat de romantheorie op het ogenblik het meest gebaat is met analyses van afzonderlijke werken" (1969, p.9) heeft zeker nog niets aan geldigheid ingeboet.
- Full Text:
- Date Issued: 1981
- Authors: Renders, L E M M E
- Date: 1981
- Subjects: Raes, Hugo -- Criticism and interpretation Raes, Hugo -- De vadsige koningen Raes, Hugo -- Een faun met kille horentjes Raes, Hugo -- Het smarán, het vikka, de ronko en al de andere kleuren van de geschiedenis Dutch fiction -- 20th century -- History and criticism
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3623 , http://hdl.handle.net/10962/d1007493
- Description: De analyse van het individuele literaire werk zal steeds het begin- en eindpunt moeten zijn van de literatuurstudie in welke gedaante dan ook: "Dit neemt echter niet weg dat het begin en einde, het alfa en omega van de literaire bedrijvigheid, het literair kunstwerk als zodanig, de literaire intentie, functie en efficientie de literair, literairesthetisch, te actualiseren en te valoriseren tekst is ... " (Rutten, 1973, p.144). Juist deze vorm van onderzoek lijkt op het ogenblik soms weI eens verloren te raken tussen de veelheid van literaire theorieen die overal opgang maken. De beoefenaars van de literaire kritiek lijken dikwijls meer begaan met het opbouwen en afbreken van theorieen dan met het literaire werk zelf. Sinds W. Bloks studie Verhaal en lezer in 1960 voor het eerst het licht zag, mag er dan op het gebied van de literatuurwetenschap in de Nederlanden en daarbuiten heel wat veranderd zijn, maar zijn uitspraak: " ... dat de romantheorie op het ogenblik het meest gebaat is met analyses van afzonderlijke werken" (1969, p.9) heeft zeker nog niets aan geldigheid ingeboet.
- Full Text:
- Date Issued: 1981
In search of true humanity : a voice of protest
- Ntshebe, Ephraim Lulamile Cootler
- Authors: Ntshebe, Ephraim Lulamile Cootler
- Date: 1981
- Subjects: Church and state -- South Africa Christianity and politics -- South Africa Apartheid -- Religious aspects Human rights -- South Africa Race relations -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:1221 , http://hdl.handle.net/10962/d1001551
- Description: My duty and aim in the writing of the thesis was neither based on scholarship nor on the fluttering of the dove coates of theological orthodoxy, but on the interpretation of the austere nature of the life of black people under the Nationalist Party rule of Apartheid. My duty, therefore, is that of an interpreter of the situation. There is nothing academic about apartheid. What is there is the monstrous evil perpetuated through the genius of the Afrikaner-Broederbond and the Afrikaans Churches and to a lesser extent by the liberal white community within the confines of South Africa (Introduction, p. vii)
- Full Text:
- Date Issued: 1981
- Authors: Ntshebe, Ephraim Lulamile Cootler
- Date: 1981
- Subjects: Church and state -- South Africa Christianity and politics -- South Africa Apartheid -- Religious aspects Human rights -- South Africa Race relations -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:1221 , http://hdl.handle.net/10962/d1001551
- Description: My duty and aim in the writing of the thesis was neither based on scholarship nor on the fluttering of the dove coates of theological orthodoxy, but on the interpretation of the austere nature of the life of black people under the Nationalist Party rule of Apartheid. My duty, therefore, is that of an interpreter of the situation. There is nothing academic about apartheid. What is there is the monstrous evil perpetuated through the genius of the Afrikaner-Broederbond and the Afrikaans Churches and to a lesser extent by the liberal white community within the confines of South Africa (Introduction, p. vii)
- Full Text:
- Date Issued: 1981
Labour migration, marriage and family life in a Ciskei village
- Authors: Manona, Cecil Wele
- Date: 1981
- Subjects: Migrant labor -- Social aspects -- South Africa -- Ciskei
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2107 , http://hdl.handle.net/10962/d1006884
- Description: From introduction: The aim of this thesis is to describe and analyse the effects of labour migration on marriage and family life. The field material is from Burnshill, a village situated in the Keiskammahoek district in the Ciskei. Keiskammahoek is bounded on the East by the districts of King William's Town and Stutterheim, on the West and South by Middledrift and on the North by Cathcart. The inhabitants of Burnshill are overwhelmingly Xhosa and Mfengu (the main ethnic groups in the Ciskei) but also include a small proportion of people whose clans are of Mpondo and Thembu origin. This village has undergone extensive change. As we shall show later, it was settled de novo by the Mfengu and the Xhosa during the second half of the past century. This is one of the reasons why it lacks the homogeneity and continuity of cultural tradition which are predominant features of long-established communities.
- Full Text:
- Date Issued: 1981
- Authors: Manona, Cecil Wele
- Date: 1981
- Subjects: Migrant labor -- Social aspects -- South Africa -- Ciskei
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2107 , http://hdl.handle.net/10962/d1006884
- Description: From introduction: The aim of this thesis is to describe and analyse the effects of labour migration on marriage and family life. The field material is from Burnshill, a village situated in the Keiskammahoek district in the Ciskei. Keiskammahoek is bounded on the East by the districts of King William's Town and Stutterheim, on the West and South by Middledrift and on the North by Cathcart. The inhabitants of Burnshill are overwhelmingly Xhosa and Mfengu (the main ethnic groups in the Ciskei) but also include a small proportion of people whose clans are of Mpondo and Thembu origin. This village has undergone extensive change. As we shall show later, it was settled de novo by the Mfengu and the Xhosa during the second half of the past century. This is one of the reasons why it lacks the homogeneity and continuity of cultural tradition which are predominant features of long-established communities.
- Full Text:
- Date Issued: 1981
Message to be broadcast over the SABC by the Vice-Chancellor on plans and prospects for Rhodes University in 1981
- Authors: Henderson, Derek Scott
- Date: 1981
- Language: English
- Type: text
- Identifier: vital:7444 , http://hdl.handle.net/10962/d1018321
- Description: The year 1980 has been a good one for Rhodes University, both academically and financially. In the academic sphere, the University launched the M.Sc degree course in Limnology and there have been extensions to the courses offered in African History and in English in Africa. The major development, however, has been the establishment of two new chairs - one in Electronics and the other in English-Second- Language, endowed respectively by Federale Electronics and the Molteno Brothers' Trust.
- Full Text:
- Date Issued: 1981
- Authors: Henderson, Derek Scott
- Date: 1981
- Language: English
- Type: text
- Identifier: vital:7444 , http://hdl.handle.net/10962/d1018321
- Description: The year 1980 has been a good one for Rhodes University, both academically and financially. In the academic sphere, the University launched the M.Sc degree course in Limnology and there have been extensions to the courses offered in African History and in English in Africa. The major development, however, has been the establishment of two new chairs - one in Electronics and the other in English-Second- Language, endowed respectively by Federale Electronics and the Molteno Brothers' Trust.
- Full Text:
- Date Issued: 1981
Mineralogy and petrology of two kimberlites at Dutoitspan Mine, Kimberley
- Authors: Snowden, D V
- Date: 1981
- Subjects: Kimberlite -- South Africa -- Kimberley , Mineralogy -- South Africa -- Kimberley , Petrology -- South Africa -- Kimberley
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4929 , http://hdl.handle.net/10962/d1004706
- Description: The mineralogy and petrology of two kimberlites, a peripheral monticellite kimberlite, and its core of phlogopite kimberlite, from the West Auxiliary Pipe at Dutoitspan Mine are described. The mineralogy of the two kimberlites differs mainly in the presence of phlogopite macrocrysts, greater abundance of angular crustal inclusions, more heavy minerals and higher diamond grade in the phlogopite type. Microprobe analyses of olivine, phlogopite, monticellite, oxide minerals and garnet are presented. Silicate compositions are comparable in both kimberlites and zoning of olivine grains is typically towards a rim of Fo₈₉₋₉₀ʻ irrespective of whether cores are more Fe-rich or more Mg-rich. This is caused by re-equilibration after fluidised emplacement in the earth's crust of macrocryst-bearing kimberlite magma. Olivine aggregates were derived from sheared mantle lherzolite and single-crystal macrocrysts were formed at higher mantle levels from a kimberlitic crystal-mush magma. This was emplaced in the crust by rapid gas streaming. The post-fluidisation phenocrysts of olivine and phlogopite which formed then are in general more Fe-rich than macrocrysts. Re-equilibration of ilmenite results in the formation of complex perovskite and titanomagnetite mantles. Phlogopite macrocrysts are preserved in the monticellite contact rock where rapid quenching prevented their resorption and allowed separation of an immiscible carbonate melt, giving the abundant groundmass calcite. Atoll-textured spinels are found in the contact rock. Major and minor trace-element analyses of whole rock samples are presented and discussed, bringing into account the problem of contamination by crustal inclusions. Whole rock chemistry supports derivation of the kimberlites as partial melts of mantle material in the presence of a lithophile-element-enriched fluid. The monticellite contact rock is highly enriched in REE, Nb, and Sr due to rapid freezing of this perovskite-enriched phase. The monticellite type is more enriched in lithophile elements than the phlogopite type, which supports derivation of the monticellite type by a small degree of partial melting, further melting reducing the relative concentrations of lithophile elements to give the phlogopite kimberlite chemistry.
- Full Text:
- Date Issued: 1981
- Authors: Snowden, D V
- Date: 1981
- Subjects: Kimberlite -- South Africa -- Kimberley , Mineralogy -- South Africa -- Kimberley , Petrology -- South Africa -- Kimberley
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4929 , http://hdl.handle.net/10962/d1004706
- Description: The mineralogy and petrology of two kimberlites, a peripheral monticellite kimberlite, and its core of phlogopite kimberlite, from the West Auxiliary Pipe at Dutoitspan Mine are described. The mineralogy of the two kimberlites differs mainly in the presence of phlogopite macrocrysts, greater abundance of angular crustal inclusions, more heavy minerals and higher diamond grade in the phlogopite type. Microprobe analyses of olivine, phlogopite, monticellite, oxide minerals and garnet are presented. Silicate compositions are comparable in both kimberlites and zoning of olivine grains is typically towards a rim of Fo₈₉₋₉₀ʻ irrespective of whether cores are more Fe-rich or more Mg-rich. This is caused by re-equilibration after fluidised emplacement in the earth's crust of macrocryst-bearing kimberlite magma. Olivine aggregates were derived from sheared mantle lherzolite and single-crystal macrocrysts were formed at higher mantle levels from a kimberlitic crystal-mush magma. This was emplaced in the crust by rapid gas streaming. The post-fluidisation phenocrysts of olivine and phlogopite which formed then are in general more Fe-rich than macrocrysts. Re-equilibration of ilmenite results in the formation of complex perovskite and titanomagnetite mantles. Phlogopite macrocrysts are preserved in the monticellite contact rock where rapid quenching prevented their resorption and allowed separation of an immiscible carbonate melt, giving the abundant groundmass calcite. Atoll-textured spinels are found in the contact rock. Major and minor trace-element analyses of whole rock samples are presented and discussed, bringing into account the problem of contamination by crustal inclusions. Whole rock chemistry supports derivation of the kimberlites as partial melts of mantle material in the presence of a lithophile-element-enriched fluid. The monticellite contact rock is highly enriched in REE, Nb, and Sr due to rapid freezing of this perovskite-enriched phase. The monticellite type is more enriched in lithophile elements than the phlogopite type, which supports derivation of the monticellite type by a small degree of partial melting, further melting reducing the relative concentrations of lithophile elements to give the phlogopite kimberlite chemistry.
- Full Text:
- Date Issued: 1981
Phambili basebenzi - Abasebenzi bemizi yeentsimbi babadudulele emva abaqashi
- Authors: General Workers Union (GWU)
- Date: 1981
- Subjects: GWU
- Language: Xhosa
- Type: text
- Identifier: http://hdl.handle.net/10962/161074 , vital:40587
- Description: Abasebenzi kwinkampani ezintathu zeentsimbi kweli lase Kapa - Trident Marine, Consani Engineering no Dorman Long bathathe inyathelo elibanzi ekukhabeni inkqubo yom- butho wabarwebi ebizwa ngokuba yi Industrial Council. Lo mbutho kwimizi yeentsimbi ngowona mkhulu apha kweli lo mzantsi Afrika. Aba baqashi bamelwe ngumbutho wabo oyi SEIFSA, ngumbutho onamandla kakhulu lo woongxowa-nkulu apha kweli lethu.
- Full Text:
- Date Issued: 1981
- Authors: General Workers Union (GWU)
- Date: 1981
- Subjects: GWU
- Language: Xhosa
- Type: text
- Identifier: http://hdl.handle.net/10962/161074 , vital:40587
- Description: Abasebenzi kwinkampani ezintathu zeentsimbi kweli lase Kapa - Trident Marine, Consani Engineering no Dorman Long bathathe inyathelo elibanzi ekukhabeni inkqubo yom- butho wabarwebi ebizwa ngokuba yi Industrial Council. Lo mbutho kwimizi yeentsimbi ngowona mkhulu apha kweli lo mzantsi Afrika. Aba baqashi bamelwe ngumbutho wabo oyi SEIFSA, ngumbutho onamandla kakhulu lo woongxowa-nkulu apha kweli lethu.
- Full Text:
- Date Issued: 1981
Poverty and social work
- Authors: Mitchell, W.A.
- Date: 1981
- Language: English
- Type: Text
- Identifier: vital:684 , http://hdl.handle.net/10962/d1020753 , ISBN 0868100757
- Description: Inaugural lecture delivered at Rhodes University , Rhodes University Libraries (Digitisation)
- Full Text:
- Date Issued: 1981
- Authors: Mitchell, W.A.
- Date: 1981
- Language: English
- Type: Text
- Identifier: vital:684 , http://hdl.handle.net/10962/d1020753 , ISBN 0868100757
- Description: Inaugural lecture delivered at Rhodes University , Rhodes University Libraries (Digitisation)
- Full Text:
- Date Issued: 1981
Primary production of Swartvlei in mid-summer 1980, with emphasis on the production ecology of the littoral zone
- Authors: Taylor, David Ian
- Date: 1981
- Subjects: Estuarine ecology -- South Africa , Estuarine ecology -- South Africa -- Swartvlei , Ecology -- Research -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5820 , http://hdl.handle.net/10962/d1007320 , Estuarine ecology -- South Africa , Estuarine ecology -- South Africa -- Swartvlei , Ecology -- Research -- South Africa
- Description: From Introduction: Energy passes through an ecosystem via a multiplicity of interconnected routes, which can be broadly categorised into trophic and detrital pathways. The "metabolic activity" of most lakes will be governed predcminantly at the base of these two routes; namely, the primary producer and decanposer levels, respectively (Wetzel and Allen, 1972). The importance of the littoral primary producers (especially the aquatic macrophytes) in the functioning of the Swartvlei ecosystem has been emphasised in a comprehensive report by Howard-Williams and Allanson (1978) dealing with the lake system fran 1975 to 1978. They noted that although the littoral shelf (<2m below low water level) occupies only 43% of the lake's surface area it contributed 64% of the total annual primary production during the period investigated. This was largely due to the dense Potamogeton pectinatus stands which alone accounted for 52% of the total carbon input into the lake by plants. The fact that the production/biomass ratio for P. pectinatus was only 1,2:1 suggested that its importance as a primary producer in Swartvlei was largely due to its high bianass. (Biomass, or standing stock, is used in this report as defined by Waters (1977); namely, "the amount present at a point in time, expressed best as quantity per spatial unit".)
- Full Text:
- Date Issued: 1981
- Authors: Taylor, David Ian
- Date: 1981
- Subjects: Estuarine ecology -- South Africa , Estuarine ecology -- South Africa -- Swartvlei , Ecology -- Research -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5820 , http://hdl.handle.net/10962/d1007320 , Estuarine ecology -- South Africa , Estuarine ecology -- South Africa -- Swartvlei , Ecology -- Research -- South Africa
- Description: From Introduction: Energy passes through an ecosystem via a multiplicity of interconnected routes, which can be broadly categorised into trophic and detrital pathways. The "metabolic activity" of most lakes will be governed predcminantly at the base of these two routes; namely, the primary producer and decanposer levels, respectively (Wetzel and Allen, 1972). The importance of the littoral primary producers (especially the aquatic macrophytes) in the functioning of the Swartvlei ecosystem has been emphasised in a comprehensive report by Howard-Williams and Allanson (1978) dealing with the lake system fran 1975 to 1978. They noted that although the littoral shelf (<2m below low water level) occupies only 43% of the lake's surface area it contributed 64% of the total annual primary production during the period investigated. This was largely due to the dense Potamogeton pectinatus stands which alone accounted for 52% of the total carbon input into the lake by plants. The fact that the production/biomass ratio for P. pectinatus was only 1,2:1 suggested that its importance as a primary producer in Swartvlei was largely due to its high bianass. (Biomass, or standing stock, is used in this report as defined by Waters (1977); namely, "the amount present at a point in time, expressed best as quantity per spatial unit".)
- Full Text:
- Date Issued: 1981
Review of carbonate hosted lead-zinc (copper) deposits and the geological factors affecting their shape, size and grade
- Authors: McDonald, B
- Date: 1981
- Subjects: Lead ores , Zinc ores , Copper ores , Sedimentology , Sedimentation and deposition
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5028 , http://hdl.handle.net/10962/d1006903
- Description: From Introduction: For at least two centuries and a corresponding number of generations of geologists and miners there has been active argument concerning the origin of certain types of carbonate hosted mineral deposit. The characterization of the type itself was and still is debatable. Objections have been raised to grouping several examples under one heading because each has its individually distinctive features. ·This is especially applicable to the carbonate hosted lead-zinc "sedimentary" deposits. The type that will be discussed in the text to follow is composed chiefly of galena, sphalerite, barite and fluorite, with pyrite , marcasite and chalcopyrite as conspicuous accessory ore minerals. Exceptions to this general copper deficient characteristic displayed by the sedimentary carbonate-hosted lead-zinc deposits are the deposits at Tsumeb and Kombat, Namibia. These deposits are hosted by the carbonate sequence of the Otavi Shelf sediments, and copper, in the form of tennantite, chalcopyrite and bornite, is the major ore constituent. Calcite, aragonite, dolomite and quartz are the commonest nonmetallic gangue minerals but siderite and silica may also be present. In contrast with other lead and zinc sulphide (volcanogenic) deposits, those to be considered here seldom carry noteworthy amounts of silver or any other precious metals. Commonly the country rock is a carbonate; limestone or dolomite, but deposits in. sandstone, shale and conglomerate are not unknown. Characteristic features are ore bodies that extend parallel or nearly so with the bedding although many such deposits are partly, or completely developed along crosscutting fissures and breccias. Some observers regard these fissure fillings as evidence for a magmatic source of the metals, whereas others regard them as an indication of remobilization of ions, metals or minerals orginally present in low-grade stratiform deposits elsewhere in the stratigraphic succession.
- Full Text:
- Date Issued: 1981
- Authors: McDonald, B
- Date: 1981
- Subjects: Lead ores , Zinc ores , Copper ores , Sedimentology , Sedimentation and deposition
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5028 , http://hdl.handle.net/10962/d1006903
- Description: From Introduction: For at least two centuries and a corresponding number of generations of geologists and miners there has been active argument concerning the origin of certain types of carbonate hosted mineral deposit. The characterization of the type itself was and still is debatable. Objections have been raised to grouping several examples under one heading because each has its individually distinctive features. ·This is especially applicable to the carbonate hosted lead-zinc "sedimentary" deposits. The type that will be discussed in the text to follow is composed chiefly of galena, sphalerite, barite and fluorite, with pyrite , marcasite and chalcopyrite as conspicuous accessory ore minerals. Exceptions to this general copper deficient characteristic displayed by the sedimentary carbonate-hosted lead-zinc deposits are the deposits at Tsumeb and Kombat, Namibia. These deposits are hosted by the carbonate sequence of the Otavi Shelf sediments, and copper, in the form of tennantite, chalcopyrite and bornite, is the major ore constituent. Calcite, aragonite, dolomite and quartz are the commonest nonmetallic gangue minerals but siderite and silica may also be present. In contrast with other lead and zinc sulphide (volcanogenic) deposits, those to be considered here seldom carry noteworthy amounts of silver or any other precious metals. Commonly the country rock is a carbonate; limestone or dolomite, but deposits in. sandstone, shale and conglomerate are not unknown. Characteristic features are ore bodies that extend parallel or nearly so with the bedding although many such deposits are partly, or completely developed along crosscutting fissures and breccias. Some observers regard these fissure fillings as evidence for a magmatic source of the metals, whereas others regard them as an indication of remobilization of ions, metals or minerals orginally present in low-grade stratiform deposits elsewhere in the stratigraphic succession.
- Full Text:
- Date Issued: 1981
Review of the Indo-Pacific pipefish genus Doryrhamphus Kaup (Pisces: Syngnathidae) with descriptions of a new species and a new subspecies
- Dawson, C E (Charles E.), 1922-
- Authors: Dawson, C E (Charles E.), 1922-
- Date: 1981
- Subjects: Pipefishes -- Indo-Pacific Region -- Classification
- Language: English
- Type: Text
- Identifier: vital:14990 , http://hdl.handle.net/10962/d1018959 , Ichthyological Bulletin of the J.L.B. Smith Institute of Ichthyology; No. 44
- Description: Dawson, C.E. 1981. Review of the Indo-Pacific Pipefish Genus Doryrhamphus Kaup (Pisces: Syngnathidae), with Descriptions of a New Species and a New Subspecies. Ichthyological Bulletin of the J.L.B. Smith Institute of Ichthyology, No. 44, 27 pages, 17 figures. Doryrhamphus, a genus of trunk-pouch pipefishes commonly associated with rock or coral habitats, is diagnosed and a key is provided to the five species and five subspecies recognized. The genus Dentirostrum Herald and Randall is synonymized with Doryrhamphus, treated species and subspecies are diagnosed and illustrated, distribution (based on material examined) is delineated and comprehensive synonymies are provided. The genus includes two species groups which, (in subadults and adults) differ in having either one or two spines on principal ridges of the posterior predorsal rings. Species of the single-spine group are distinguished by differences in meristic values and preserved coloration, as well as by the presence of one or two ventrolateral projections on the snout of males, or the absence thereof. Species of the two-spine group are distinguished by differences in meristic values and preserved coloration, as well as by the presence of either one or two spines on principal ridges of tail rings. The single-spine group includes the type-species, D. excisus (three subspecies), with one ventrolateral projection on snout in males, A japonicus with no projection on snout, and D. bicarinatus n. sp. with two projections on snout. Doryrhamphus e. excisus (a senior synonym of D. melanopleura), with modally 17-18 trunk rings ranges from eastern Africa and Persian Gulf to the west coast of the Americas. This pipefish, the most widely distributed syngnathid, exhibits some west-east clinal increase in counts of total rings and dorsal-fin rays. Doryrhamphus e. abbreviatus n. ssp. is a Red Sea endemic characterized by modally 16 trunk rings as well as by 26-28 total rings and 18-20 dorsal-fin rays. D. e. paulus (Revillagegido Is., Mexico) shares the modal count of 16 trunk rings, but has 30-32 total rings and 23-27 dorsal-fin rays. D. japonicus (19-20 trunk rings) is known only from the main islands of Japan, whereas D. bicarinatus (16 trunk rings) is known from Indian Ocean coasts of South Africa and Mozambique. The two-spine group includes D. negrosensis (2 subspecies) with 2 spines on ridges of tail rings in subadults and adults and A janssi (one spine on ridges of tail rings. A n. negrosensis (modally 15 trunk and 29 total rings) is known from Borneo to the Ryukyu Is. and southeastward to the New Hebrides, excluding Australia. D. n. malus (modally, 16 trunk and 31 total rings) is an Australian Great Barrier Reef endemic. D. janssi, with more tail rings than D. negrosensis (21-23 versus 13-16), is known from the eastern Indian Ocean (off NW Australia) and from the Gulf of Thailand and Philippines southeastward to New Guinea and NE Australia in the western Pacific Ocean. Planktonic young of A excisus and early juveniles of D. negrosensis are illustrated and briefly described. , Rhodes University Libraries (Digitisation)
- Full Text:
- Date Issued: 1981
- Authors: Dawson, C E (Charles E.), 1922-
- Date: 1981
- Subjects: Pipefishes -- Indo-Pacific Region -- Classification
- Language: English
- Type: Text
- Identifier: vital:14990 , http://hdl.handle.net/10962/d1018959 , Ichthyological Bulletin of the J.L.B. Smith Institute of Ichthyology; No. 44
- Description: Dawson, C.E. 1981. Review of the Indo-Pacific Pipefish Genus Doryrhamphus Kaup (Pisces: Syngnathidae), with Descriptions of a New Species and a New Subspecies. Ichthyological Bulletin of the J.L.B. Smith Institute of Ichthyology, No. 44, 27 pages, 17 figures. Doryrhamphus, a genus of trunk-pouch pipefishes commonly associated with rock or coral habitats, is diagnosed and a key is provided to the five species and five subspecies recognized. The genus Dentirostrum Herald and Randall is synonymized with Doryrhamphus, treated species and subspecies are diagnosed and illustrated, distribution (based on material examined) is delineated and comprehensive synonymies are provided. The genus includes two species groups which, (in subadults and adults) differ in having either one or two spines on principal ridges of the posterior predorsal rings. Species of the single-spine group are distinguished by differences in meristic values and preserved coloration, as well as by the presence of one or two ventrolateral projections on the snout of males, or the absence thereof. Species of the two-spine group are distinguished by differences in meristic values and preserved coloration, as well as by the presence of either one or two spines on principal ridges of tail rings. The single-spine group includes the type-species, D. excisus (three subspecies), with one ventrolateral projection on snout in males, A japonicus with no projection on snout, and D. bicarinatus n. sp. with two projections on snout. Doryrhamphus e. excisus (a senior synonym of D. melanopleura), with modally 17-18 trunk rings ranges from eastern Africa and Persian Gulf to the west coast of the Americas. This pipefish, the most widely distributed syngnathid, exhibits some west-east clinal increase in counts of total rings and dorsal-fin rays. Doryrhamphus e. abbreviatus n. ssp. is a Red Sea endemic characterized by modally 16 trunk rings as well as by 26-28 total rings and 18-20 dorsal-fin rays. D. e. paulus (Revillagegido Is., Mexico) shares the modal count of 16 trunk rings, but has 30-32 total rings and 23-27 dorsal-fin rays. D. japonicus (19-20 trunk rings) is known only from the main islands of Japan, whereas D. bicarinatus (16 trunk rings) is known from Indian Ocean coasts of South Africa and Mozambique. The two-spine group includes D. negrosensis (2 subspecies) with 2 spines on ridges of tail rings in subadults and adults and A janssi (one spine on ridges of tail rings. A n. negrosensis (modally 15 trunk and 29 total rings) is known from Borneo to the Ryukyu Is. and southeastward to the New Hebrides, excluding Australia. D. n. malus (modally, 16 trunk and 31 total rings) is an Australian Great Barrier Reef endemic. D. janssi, with more tail rings than D. negrosensis (21-23 versus 13-16), is known from the eastern Indian Ocean (off NW Australia) and from the Gulf of Thailand and Philippines southeastward to New Guinea and NE Australia in the western Pacific Ocean. Planktonic young of A excisus and early juveniles of D. negrosensis are illustrated and briefly described. , Rhodes University Libraries (Digitisation)
- Full Text:
- Date Issued: 1981
Rhodes University 1981 Graduation Ceremonies Address
- Authors: Henderson, Derek Scott
- Date: 1981
- Language: English
- Type: text
- Identifier: vital:7428 , http://hdl.handle.net/10962/d1018305
- Full Text:
- Date Issued: 1981
- Authors: Henderson, Derek Scott
- Date: 1981
- Language: English
- Type: text
- Identifier: vital:7428 , http://hdl.handle.net/10962/d1018305
- Full Text:
- Date Issued: 1981
Rhodes University Annual Report 1981
- Authors: Rhodes University
- Date: 1981
- Subjects: Rhodes University -- history Rhodes University -- employees Rhodes University -- students
- Language: English
- Type: text
- Identifier: vital:20015
- Full Text:
- Date Issued: 1981
- Authors: Rhodes University
- Date: 1981
- Subjects: Rhodes University -- history Rhodes University -- employees Rhodes University -- students
- Language: English
- Type: text
- Identifier: vital:20015
- Full Text:
- Date Issued: 1981
Rhodes University Graduation Ceremony 1981
- Authors: Rhodes University
- Date: 1981
- Language: English
- Type: text
- Identifier: vital:8118 , http://hdl.handle.net/10962/d1004897
- Description: Rhodes University Graduation Ceremony on Friday, 10 April 1981 at 8 p.m. [and] on Saturday, 11 April 1981 at 10 a.m. in the 1820 Settlers National Monument.
- Full Text:
- Date Issued: 1981
- Authors: Rhodes University
- Date: 1981
- Language: English
- Type: text
- Identifier: vital:8118 , http://hdl.handle.net/10962/d1004897
- Description: Rhodes University Graduation Ceremony on Friday, 10 April 1981 at 8 p.m. [and] on Saturday, 11 April 1981 at 10 a.m. in the 1820 Settlers National Monument.
- Full Text:
- Date Issued: 1981
Résultats des études menées en Angleterre: détermination de la posologie optimale
- Woodford, R, Haigh, John M, Barry, B W
- Authors: Woodford, R , Haigh, John M , Barry, B W
- Date: 1981
- Language: French
- Type: Article
- Identifier: vital:6449 , http://hdl.handle.net/10962/d1006636
- Description: Les auteurs ont etudie la biodisponibilite et I'activite de formules experimentales et commercialisees de dermocortico'ides en utilisant les essais de vasoconstriction avec et sans occlusion (1, 2, 6, 7, 8, 9). L'application unique de six heures avec lectures multiples a ete largement utilisee dans ce travail et la methodologie en a ete decrite en detail ailleurs (4). Sur la base de ce travail. on a pratique des applications repetees de dermocortico'ides commercialises au Royaume- Uni. en utilisant Ie test du blanchiment de la peau sans occlusion, de maniere a reproduire au plus pres la situation realisee en clinique (3). Ce travail a montre que I'application de cortico'ides trois fois par jour pendant cinq jours aboutissait a une tachyphylaxie considerable de la reponse du blanchiment quelque soit I'activite therapeutique de la formule utilisee. Au bout de deux jours de repos, on a assiste a une recuperation considerable, mais a nouveau une tachyphylaxie aigue s'est installee a la suite d'une nouvelle application triquotidienne.
- Full Text:
- Date Issued: 1981
- Authors: Woodford, R , Haigh, John M , Barry, B W
- Date: 1981
- Language: French
- Type: Article
- Identifier: vital:6449 , http://hdl.handle.net/10962/d1006636
- Description: Les auteurs ont etudie la biodisponibilite et I'activite de formules experimentales et commercialisees de dermocortico'ides en utilisant les essais de vasoconstriction avec et sans occlusion (1, 2, 6, 7, 8, 9). L'application unique de six heures avec lectures multiples a ete largement utilisee dans ce travail et la methodologie en a ete decrite en detail ailleurs (4). Sur la base de ce travail. on a pratique des applications repetees de dermocortico'ides commercialises au Royaume- Uni. en utilisant Ie test du blanchiment de la peau sans occlusion, de maniere a reproduire au plus pres la situation realisee en clinique (3). Ce travail a montre que I'application de cortico'ides trois fois par jour pendant cinq jours aboutissait a une tachyphylaxie considerable de la reponse du blanchiment quelque soit I'activite therapeutique de la formule utilisee. Au bout de deux jours de repos, on a assiste a une recuperation considerable, mais a nouveau une tachyphylaxie aigue s'est installee a la suite d'une nouvelle application triquotidienne.
- Full Text:
- Date Issued: 1981
Sampling in the evaluation of ore deposits
- Authors: Grant, D E C S
- Date: 1981 , 2013-03-19
- Subjects: Ore deposits , Mine valuation , Ores -- Sampling and estimation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5008 , http://hdl.handle.net/10962/d1005912 , Ore deposits , Mine valuation , Ores -- Sampling and estimation
- Description: Sampling is an error generating process and these errors should be reduced to a minimum if an accurate ore reserve estimation is to be made from the sample values. Error in sampling can arise from the sampling procedure as well as where and how each sample is taken from the deposit . Sampling procedure involves sample collection, sample reduction and analysis, and the error from each of these three stages has an equal influence on the total error of the process. Error due to sampling procedure should be identified and eliminated at an early stage in the evaluation programme. An ore deposit should be subdivided into sampling strata along geological boundaries, and once these boundaries have been established they should be adhered to for the evaluation programme. The sampling of each stratum depends on the small-scale structures in which the grade is distributed, and this distribution in relation to sample size controls sample variance, sample bias and the volume of influence of each sample. Cluster sampling can be used where an impractically large sample is necessary to reduce sample variance or increase the volume of influence of samples. Sample bias can be reduced by composing a large number of small samples . Sampling patterns should be designed with reference to the volumes of influence of samples, and in favourable geology, geostatistical or statistical techniques can be used to predict the precision of an ore reserve estimation 1n terms of the number of samples taken. Different are deposits have different sampling characteristics and problems which can be directly related to the geology of the mineralization. If geology is disregarded when sampling an are deposit, an evaluation programme cannot claim to give an accurate estimate of the ore reserves .
- Full Text:
- Date Issued: 1981
- Authors: Grant, D E C S
- Date: 1981 , 2013-03-19
- Subjects: Ore deposits , Mine valuation , Ores -- Sampling and estimation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5008 , http://hdl.handle.net/10962/d1005912 , Ore deposits , Mine valuation , Ores -- Sampling and estimation
- Description: Sampling is an error generating process and these errors should be reduced to a minimum if an accurate ore reserve estimation is to be made from the sample values. Error in sampling can arise from the sampling procedure as well as where and how each sample is taken from the deposit . Sampling procedure involves sample collection, sample reduction and analysis, and the error from each of these three stages has an equal influence on the total error of the process. Error due to sampling procedure should be identified and eliminated at an early stage in the evaluation programme. An ore deposit should be subdivided into sampling strata along geological boundaries, and once these boundaries have been established they should be adhered to for the evaluation programme. The sampling of each stratum depends on the small-scale structures in which the grade is distributed, and this distribution in relation to sample size controls sample variance, sample bias and the volume of influence of each sample. Cluster sampling can be used where an impractically large sample is necessary to reduce sample variance or increase the volume of influence of samples. Sample bias can be reduced by composing a large number of small samples . Sampling patterns should be designed with reference to the volumes of influence of samples, and in favourable geology, geostatistical or statistical techniques can be used to predict the precision of an ore reserve estimation 1n terms of the number of samples taken. Different are deposits have different sampling characteristics and problems which can be directly related to the geology of the mineralization. If geology is disregarded when sampling an are deposit, an evaluation programme cannot claim to give an accurate estimate of the ore reserves .
- Full Text:
- Date Issued: 1981