纳米比亚欢乐谷地区白岗岩岩石学及地球化学特征
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摘要
对纳米比亚欢乐谷地区的白岗岩进行了详细的岩石学和地球化学特征研究,初步讨论了白岗岩成因。研究结果表明,欢乐谷地区白岗岩的矿物组成和化学成分显示了较大的变化范围,白岗岩岩性主要为正长花岗岩和二长花岗岩,部分为碱长花岗岩、英云闪长岩和花岗闪长岩等。根据岩石和矿物的颜色、结构、矿物学特征、矿化特点等,可将其划分为A、B、C、D、E、F 6种类型,并且从A类至F类,白岗岩的形成时间顺序为由早到晚。白岗岩具有高硅、高碱和低锰、镁、钠、磷、钙的特点,为高钾钙碱性系列钾玄岩系列的准铝质过铝质岩石。不同类型的白岗岩主量元素特征未显示出它们是同源岩浆演化的产物,而可能是达马拉造山运动晚期构造演化不同阶段的产物。
The Gaudeanmus area lies within the southern Central Zone of the NE-trending branch of the Damara orogen. Petrographical and geochemical characteristics of alaskite as well as its petrogenesis and geological features in the Gaudeanmus area of Namiba were studied in this paper. The alaskite sample displays variable mineral and chemical composition. The alaskites in this area range in composition from tonalite to alkali-feldspar granite. The alaskites have been divided into six distinct types based wholly on observable field characteristics of color, grain size, texture, radiometric measurements by scintillometer and macro-scale mineralogy. Cross-cutting and structural relationships were used to create a chronological sequence from type A which is the oldest to type F which is the youngest. Geochemical analyses show that the alaskites contain high silica and alkali, with relatively low manganese, magnesium, sodium, phosphor and calcium. The alaskites show peraluminous to metaluminous characteristics and belong to high-K calc-alkaline to shoshonite series. Major elements of different types of alaskites do not show characteristics of homogeneous evolution, so they are inferred to be products of different stages of orogeny.
The Gaudeanmus area lies within the southern Central Zone of the NE-trending branch of the Damara orogen. Petrographical and geochemical characteristics of alaskite as well as its petrogenesis and geological features in the Gaudeanmus area of Namiba were studied in this paper. The alaskite sample displays variable mineral and chemical composition. The alaskites in this area range in composition from tonalite to alkali-feldspar granite. The alaskites have been divided into six distinct types based wholly on observable field characteristics of color, grain size, texture, radiometric measurements by scintillometer and macro-scale mineralogy. Cross-cutting and structural relationships were used to create a chronological sequence from type A which is the oldest to type F which is the youngest. Geochemical analyses show that the alaskites contain high silica and alkali, with relatively low manganese, magnesium, sodium, phosphor and calcium. The alaskites show peraluminous to metaluminous characteristics and belong to high-K calc-alkaline to shoshonite series. Major elements of different types of alaskites do not show characteristics of homogeneous evolution, so they are inferred to be products of different stages of orogeny.
引文
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Batchelor R A and Bowden P.1985.Petrogenetic interpretation of granit-oid rock series using multicationic parameters[J].Chem.Geol.,48:43~55.
Berning J,Cooke R,Heimstra S,et al.1976.The Rssing Uranium Deposit,South West Africa[J].Economic Geology,71:351~368.
Corner B.1983.An interpretation of the aeromagnetic data covering thewestern portion of the Damara Orogen in South West Africa/Namibia[A].Miller R.Evolution of the Damara Orogen of South West Africa/Namibia[C].Geological Society of South Africa,Special Publications,11:339~354.
Corner B and Henthorn D I.1978.Results of a palaeomagnetic survey undertaken in the Damara mobile belt,South West Africa,with specialreference to the magnetisation of the uraniferous pegmatitic granites[R].Report PEL-260 Pelindaba,Atomic Energy Board South Africa.
Coward M P.1983.The tectonic history of the Damaran Belt[A].MillerR.Evolution of the Damara Orogen of South West Africa/Namibia[C].Geological Society of South Africa,Special Publications,11:409~422.
Hawkesworth C J and Marlow A G.1983.Isotopic evolution of the DamaraOrogenic Belt[A].Miller R.Evolution of the Damara Orogen ofSouth West Africa/Namibia[C].Geological Society of South Africa,Special Publications,11:397~408.
Henry G,Clendenin C W,Stannistreet I G,et al.1990.Multiple detachment model for the early rifting stage of the Late ProterozoicDamara orogen in Namibia[J].Geology,18:67~71.
Herd D A.1996.Geochemistry and Mineralisation of Alaskite in SelectedAreas of the Rssing Uranium Mine,Namibia[D].MSc thesis,University of St.Andrews.
Jacob R E,Corner B,Brynard H J,et al.1986.The regional structuraland geological setting of the uraniferous granitic provinces of SouthernAfrica[A].Anhaeusser C R and Maske S.Mineral Deposits ofSouthern Africa,II[C].Geological Society of South Africa,Johannesburg,1 807~1 818.
Kinnaird J A and Nex P A M.2007.A review of geological controls on uranium mineralization in sheeted leucogranites within the DamaranOrogen,Namibia[J].Applied Earth Science,116(2):68~85.
Krner A,Retief E A,Compston W,et al.1991.Single-age and conventional zircon dating of remobilised basement gneisses in the centralDamara belt of Namibia[J].South African Journal of Geology,94:379~387.
Kukla C,Kramm U,Kukla P A,et al.1991.U-Pb monazite data relating to metamorphism and granite intrusion in the northwestern Khomas Trough,Damara Orogen,central Namibia[J].Commun.Geol.Surv.Namibia,7:49~54.
Le Maitre R W.1989.A Classification of Igneous Rocks and Glossary ofTerms:Recommendations of the International Union of Geological Sciences,Subcommission on the Systematics of Igneous Rocks[M].Oxford:Blackwell,193.
London D.1992.The application of experimental petrology to the genesisand crystallisation of granitic pegmatites[J].Canadian Min-eralogist,30:499~540.
Maniar P D and Piccoli P M.1989.Tectonic discrimination of granitoids[J].GSA Bull.,101(5):635~643.
Marlow A G.1983.Geology and Rb-Sr geochronology of mineralised andradioactive granites and alaskites,Namibia[A].Miller R Mc G.Evolution of the Damara Orogen of South West Africa/Namibia[C].Geological Society of South Africa,Special Publication 11,289~298.
Martin H and Porada H.1977.The intracratonic branch of the DamaranOrogen in Namibia.Discussion of geodynamic models[J].Precambrian Research,5:311~338.
Mc Dermott F.1986.Granite Petrogenesis and Crustal Evolution Studies inthe Damara Pan-African Otogenic Belt,Namibia[D].Ph D Thesis,The Open University.
Mc Dermott F,Harris N B W&Hawkesworth C J.1996.Geochemicalconstraints on crustal anatexis:a case study from the Pan-AfricanDamara granitoids of Namibia[J].Contributions to Mineralogy andPetrology,123:406~423.
Mestres-Ridge D.1992.An Investigation into the Controls on the Distribution of Betatite in the SH area,Rssing Uranium Mine[D].Namibia.M.Sc Dissertation,University of St.Andrews.
Miller R M.1983.The Pan-African Damara Orogen of South West Africa/Namibia[A].Miller R Mc G.Evolution of the Damara Orogen ofSouth West Africa/Namibia[C].Geological Society of South Africa,Special Publications,11:431~515.
Nash C R.1971.Metamorphic petrology of the SJ area,SwakopmundDistrict,South West Africa[J].Bulletin of the Precambrian Research,9:77.
Nex P A M.1997.Tectono-metamorphic Setting and Evolution of GraniticSheets in the Goanikontes Area,Namibia[D].Ph.D.Thesis(Unpublished),National University of Ireland.
Nex P A M,Kinnaird J A and Oliver G J H.2001a.Petrology,geochemistry and mineralisation of post-collisional magmatism around Goanikontes,southern Central Zone,Damara Orogen,Namibia[J].Journal of African Earth Sciences,33:481~502.
Nex P A M,Kinnaird J A and Herd D A.2003.The occurrence,mineralogy and chemistry of betafite and pyrochlore from sheeted leucogranites of the Rssing area,Namibia:implications for the composition ofCeramics for radioactive waste disposal[R].Economic Geology Research Institute,School of Geosciences University of the Wit-watersrand,374:1~24.
Nex P A M,Oliver G J H and Kinnaird J A.2001b.Spinel-bearing assemblages and P-T-t evolution of the Central Zone of the Damara Orogen,Namibia[J].Journal of African Earth Sciences,32:471~489.
Oliver G J H.1994.Mid-crustal detachment and domes in the CentraZone of the Damara Orogen,Namibia[J].Journal of African EarthSciences,19:331~344.
Osterhus L and Jung S.2010.Anatexis of mafic and felsic lower crust;geochemistry and Nd,Sr and Pb isotopes of late-orogenic granodioritesand leucogranites(Damara Orogen,Namibia)[A].European Geosciences Union General Assembly 2010,Anonymous,GeophysicaResearch Abstracts[C],12.
Peccerillo R and Taylor S R.1976.Geochemistry of eocene calc-alkalinevolcanic rocks from the Kastamonu area,Northern Turkey[J].Contrib.Mineral Petrol.,58:63~81.
Roesener H and Schreuder C P.1998.Uranium in the mineral resourcesof Namibia.Ministry of Mines and Energy[J].Geological Survey Namibia,7.1-1~7.1-62.
Smith D A M.1965.The geology of the area around the Khan and Swakoprivers in South West Africa[A].Memoir of the Geological Survey oSouth Africa.South West Africa Series[C],3.
Sylvester P J.1998.Post-collisional strongly peraluminous granites[J].Lithos,45:29~44.
Wang Shengyun,Fan Honghai,Chen Jinyong,et al.2013.Petrogenesisand tectonic setting of prophyritic granites in Gaudeanmus area,Namibia[J].Global Geology,32(4):773~782(in Chinese with English abstract).
Wright J B.1969.A simple alkalinity ratio and its application to questions of non-orogenic granite genesis[J].Geological Magzine,106:370~384.
王生云,范洪海,陈金勇,等.2013.纳米比亚欢乐谷地区斑状花岗岩成因及构造背景[J].世界地质,32 (4 ):773 ~782.
Batchelor R A and Bowden P.1985.Petrogenetic interpretation of granit-oid rock series using multicationic parameters[J].Chem.Geol.,48:43~55.
Berning J,Cooke R,Heimstra S,et al.1976.The Rssing Uranium Deposit,South West Africa[J].Economic Geology,71:351~368.
Corner B.1983.An interpretation of the aeromagnetic data covering thewestern portion of the Damara Orogen in South West Africa/Namibia[A].Miller R.Evolution of the Damara Orogen of South West Africa/Namibia[C].Geological Society of South Africa,Special Publications,11:339~354.
Corner B and Henthorn D I.1978.Results of a palaeomagnetic survey undertaken in the Damara mobile belt,South West Africa,with specialreference to the magnetisation of the uraniferous pegmatitic granites[R].Report PEL-260 Pelindaba,Atomic Energy Board South Africa.
Coward M P.1983.The tectonic history of the Damaran Belt[A].MillerR.Evolution of the Damara Orogen of South West Africa/Namibia[C].Geological Society of South Africa,Special Publications,11:409~422.
Hawkesworth C J and Marlow A G.1983.Isotopic evolution of the DamaraOrogenic Belt[A].Miller R.Evolution of the Damara Orogen ofSouth West Africa/Namibia[C].Geological Society of South Africa,Special Publications,11:397~408.
Henry G,Clendenin C W,Stannistreet I G,et al.1990.Multiple detachment model for the early rifting stage of the Late ProterozoicDamara orogen in Namibia[J].Geology,18:67~71.
Herd D A.1996.Geochemistry and Mineralisation of Alaskite in SelectedAreas of the Rssing Uranium Mine,Namibia[D].MSc thesis,University of St.Andrews.
Jacob R E,Corner B,Brynard H J,et al.1986.The regional structuraland geological setting of the uraniferous granitic provinces of SouthernAfrica[A].Anhaeusser C R and Maske S.Mineral Deposits ofSouthern Africa,II[C].Geological Society of South Africa,Johannesburg,1 807~1 818.
Kinnaird J A and Nex P A M.2007.A review of geological controls on uranium mineralization in sheeted leucogranites within the DamaranOrogen,Namibia[J].Applied Earth Science,116(2):68~85.
Krner A,Retief E A,Compston W,et al.1991.Single-age and conventional zircon dating of remobilised basement gneisses in the centralDamara belt of Namibia[J].South African Journal of Geology,94:379~387.
Kukla C,Kramm U,Kukla P A,et al.1991.U-Pb monazite data relating to metamorphism and granite intrusion in the northwestern Khomas Trough,Damara Orogen,central Namibia[J].Commun.Geol.Surv.Namibia,7:49~54.
Le Maitre R W.1989.A Classification of Igneous Rocks and Glossary ofTerms:Recommendations of the International Union of Geological Sciences,Subcommission on the Systematics of Igneous Rocks[M].Oxford:Blackwell,193.
London D.1992.The application of experimental petrology to the genesisand crystallisation of granitic pegmatites[J].Canadian Min-eralogist,30:499~540.
Maniar P D and Piccoli P M.1989.Tectonic discrimination of granitoids[J].GSA Bull.,101(5):635~643.
Marlow A G.1983.Geology and Rb-Sr geochronology of mineralised andradioactive granites and alaskites,Namibia[A].Miller R Mc G.Evolution of the Damara Orogen of South West Africa/Namibia[C].Geological Society of South Africa,Special Publication 11,289~298.
Martin H and Porada H.1977.The intracratonic branch of the DamaranOrogen in Namibia.Discussion of geodynamic models[J].Precambrian Research,5:311~338.
Mc Dermott F.1986.Granite Petrogenesis and Crustal Evolution Studies inthe Damara Pan-African Otogenic Belt,Namibia[D].Ph D Thesis,The Open University.
Mc Dermott F,Harris N B W&Hawkesworth C J.1996.Geochemicalconstraints on crustal anatexis:a case study from the Pan-AfricanDamara granitoids of Namibia[J].Contributions to Mineralogy andPetrology,123:406~423.
Mestres-Ridge D.1992.An Investigation into the Controls on the Distribution of Betatite in the SH area,Rssing Uranium Mine[D].Namibia.M.Sc Dissertation,University of St.Andrews.
Miller R M.1983.The Pan-African Damara Orogen of South West Africa/Namibia[A].Miller R Mc G.Evolution of the Damara Orogen ofSouth West Africa/Namibia[C].Geological Society of South Africa,Special Publications,11:431~515.
Nash C R.1971.Metamorphic petrology of the SJ area,SwakopmundDistrict,South West Africa[J].Bulletin of the Precambrian Research,9:77.
Nex P A M.1997.Tectono-metamorphic Setting and Evolution of GraniticSheets in the Goanikontes Area,Namibia[D].Ph.D.Thesis(Unpublished),National University of Ireland.
Nex P A M,Kinnaird J A and Oliver G J H.2001a.Petrology,geochemistry and mineralisation of post-collisional magmatism around Goanikontes,southern Central Zone,Damara Orogen,Namibia[J].Journal of African Earth Sciences,33:481~502.
Nex P A M,Kinnaird J A and Herd D A.2003.The occurrence,mineralogy and chemistry of betafite and pyrochlore from sheeted leucogranites of the Rssing area,Namibia:implications for the composition ofCeramics for radioactive waste disposal[R].Economic Geology Research Institute,School of Geosciences University of the Wit-watersrand,374:1~24.
Nex P A M,Oliver G J H and Kinnaird J A.2001b.Spinel-bearing assemblages and P-T-t evolution of the Central Zone of the Damara Orogen,Namibia[J].Journal of African Earth Sciences,32:471~489.
Oliver G J H.1994.Mid-crustal detachment and domes in the CentraZone of the Damara Orogen,Namibia[J].Journal of African EarthSciences,19:331~344.
Osterhus L and Jung S.2010.Anatexis of mafic and felsic lower crust;geochemistry and Nd,Sr and Pb isotopes of late-orogenic granodioritesand leucogranites(Damara Orogen,Namibia)[A].European Geosciences Union General Assembly 2010,Anonymous,GeophysicaResearch Abstracts[C],12.
Peccerillo R and Taylor S R.1976.Geochemistry of eocene calc-alkalinevolcanic rocks from the Kastamonu area,Northern Turkey[J].Contrib.Mineral Petrol.,58:63~81.
Roesener H and Schreuder C P.1998.Uranium in the mineral resourcesof Namibia.Ministry of Mines and Energy[J].Geological Survey Namibia,7.1-1~7.1-62.
Smith D A M.1965.The geology of the area around the Khan and Swakoprivers in South West Africa[A].Memoir of the Geological Survey oSouth Africa.South West Africa Series[C],3.
Sylvester P J.1998.Post-collisional strongly peraluminous granites[J].Lithos,45:29~44.
Wang Shengyun,Fan Honghai,Chen Jinyong,et al.2013.Petrogenesisand tectonic setting of prophyritic granites in Gaudeanmus area,Namibia[J].Global Geology,32(4):773~782(in Chinese with English abstract).
Wright J B.1969.A simple alkalinity ratio and its application to questions of non-orogenic granite genesis[J].Geological Magzine,106:370~384.
王生云,范洪海,陈金勇,等.2013.纳米比亚欢乐谷地区斑状花岗岩成因及构造背景[J].世界地质,32 (4 ):773 ~782.