赞比亚东北部卡萨马—陇都地区碎屑锆石裂变径迹年代学特征
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摘要
本文利用锆石裂变径迹方法探讨了班韦乌卢地块自泛非构造运动以来的主要构造演化时间。赞比亚东北部卡萨马—陇都地区位于班韦乌卢地块中东部。班韦乌卢地块受到其东北部的古元古代乌本迪构造带、东南部的中元古代伊鲁米德构造带、西南部泛非期卢弗里安构造带及西北部的中元古代基巴拉构造带的综合影响,其主要由基底和沉积盖层两部分组成。为研究卡萨马—陇都地区的地质特征和构造活动,本文从沉积盖层中姆波罗科索群的姆巴拉组和卡萨马群中的下卡萨马组中采集多个新鲜的岩石样品,并获得4件碎屑锆石的裂变径迹分析结果。4件锆石样品的年龄变化在(482±42)～(351±32)Ma之间,具有488～441 Ma和375～293Ma两个年龄组,分别对应的主要时代为奥陶纪和石炭纪。对比邻区卢弗里安构造带、赞比西构造带、达马拉构造带和马拉维湖等地区已有的年龄数据可知,非洲中南部地区奥陶纪和石炭纪的两期构造活动涉及范围广,且班韦乌卢地块内的构造活动可能与后期冈瓦纳古陆块的解体事件有关。班韦乌卢地块地区研究程度很低,此次研究成果可为今后在该地区的深入研究提供重要参考。
The main tectonic evolution time of the Bangweulu Block since the PanAfrican tectonic activities was studied in this paper according to the zircon fission trackmethod.The Kasama—Nondo is located at mid-eastern Bangweulu Block of northeastern Zambia.Bangweulu Block which is mainly composed of basement and sedimentary rocks was comprehensively affected by northeastern Paleoproterozoic Ubendian Belt,southeastern Mesoproterozoic Irumide Belt,southwestern Pan-African Lufulian Belt and northwestern Mesoproterozoic Kibaran Belt.In order to study the geological characteristics and tectonic activities in Kasama—Nondo,some fresh rock samples from Mbala Formation of Mporokoso Group and lower Kasama Formation of Kasama Group were took and the 4 detrital zircon fission track ages are between(482±42)Ma and(351±32)Ma.The ages might be divided into two groups,i.e.488-441 Ma and 375-293 Ma,which respectively correspond to the main periods of the Ordovician and Carboniferous.Compared with the ages from Lufulian Belt,Zambezi Belt,Damara Belt and Malawi Lake area and so on,the tectonic activities of Ordovician and Carboniferous in midsouthern Africa involve wide area and the tectonic activities of Bangweulu Block may pave the way for the later disintegration of Gondwana Block.Few data on Bangweulu Block are available and the results can provide important information for the future work in the Kasama—Nondo.
The main tectonic evolution time of the Bangweulu Block since the PanAfrican tectonic activities was studied in this paper according to the zircon fission trackmethod.The Kasama—Nondo is located at mid-eastern Bangweulu Block of northeastern Zambia.Bangweulu Block which is mainly composed of basement and sedimentary rocks was comprehensively affected by northeastern Paleoproterozoic Ubendian Belt,southeastern Mesoproterozoic Irumide Belt,southwestern Pan-African Lufulian Belt and northwestern Mesoproterozoic Kibaran Belt.In order to study the geological characteristics and tectonic activities in Kasama—Nondo,some fresh rock samples from Mbala Formation of Mporokoso Group and lower Kasama Formation of Kasama Group were took and the 4 detrital zircon fission track ages are between(482±42)Ma and(351±32)Ma.The ages might be divided into two groups,i.e.488-441 Ma and 375-293 Ma,which respectively correspond to the main periods of the Ordovician and Carboniferous.Compared with the ages from Lufulian Belt,Zambezi Belt,Damara Belt and Malawi Lake area and so on,the tectonic activities of Ordovician and Carboniferous in midsouthern Africa involve wide area and the tectonic activities of Bangweulu Block may pave the way for the later disintegration of Gondwana Block.Few data on Bangweulu Block are available and the results can provide important information for the future work in the Kasama—Nondo.
引文
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[9]袁万明,张雪亭,董金泉,等.东昆仑隆升作用的裂变径迹研究[J].原子能科学技术,2004,38(2):165-168.YUAN Wanming,ZHANG Xueting,DONG Jinquan,et al.Apatite fission track evidence on the uplifting of Eastern Kunlun Mountains[J].Atomic Energy Science and Technology,2004,38(2):165-168(in Chinese).
[10]沈传波,梅廉夫,汤济广,等.大巴山逆冲推覆带构造扩展变形的年代学制约[J].原子能科学技术,2008,42(6):574-576.SHEN Chuanbo,MEI Lianfu,TANG Jiguang,et al. Geochronology evidences for tectonic deformation of Dabashan fold-thrust belt in central China[J].Atomic Energy Science and Technology,2008,42(6):574-576(in Chinese).
[11]王珂,袁万明,冯星,等.东昆仑埃坑地区磷灰石裂变径迹年代学及构造意义[J].原子能科学技术,2018,52(1):186-192.WANG Ke,YUAN Wanming,FENG Xing,et al.Apatite fission track thermochronology and tectonic significance in Aikeng area,east Kunlun mountains[J].Atomic Energy Science and Technology,2018,52(1):186-192(in Chinese).
[12]YAMADA R,TAGAMI T,NISHIMURA S,et al.Annealing kinetics of fission tracks in zircon:An experimental study[J].Chemical Geology,1995,122(1-4):249-258.
[13]赵文菊,袁万明,刘海涛,等.从裂变径迹分析新疆阿尔泰南部地区构造活动与古地形的变化[J].原子能科学技术,2013,47(8):1 458-1 467.ZHAO Wenju,YUAN Wanming,LIU Haitao,et al.Apatite fission track analysis on tectonic activities and paleotopography in southern Altai region,Xinjiang,China[J].Atomic Energy Science and Technology,2013,47(8):1 458-1 467(in Chinese).
[14]DONELICK R A,MILLER D S.Enhanced tint fission track densities in low spontaneous track density apatites using 252 Cf-derived fission fragment tracks:A model and experimental observations[J].Nuclear Tracks and Radiation Measurements,1991,18(3):301-307.
[15]GALBRAITH R F.On statistical models of fission track counts[J].Mathematical Geosciences,1981,13(6):471-478.
[16]MARK T B.Probability density plot for fissiontrack grain-age samples[J].Radiation Measurement,1996,26(5):663-676.
[17]EGLINGER A,VANDERHAEGHE O,ANDRE-MAYER A S,et al.Tectono-metamorphic evolution of the internal zone of the Pan-African Lufilian orogenic belt(Zambia):Implications for crustal reworking and syn-orogenic uranium mineralizations[J].Lithos,2016,240-243:167-188.
[18]任军平,王杰,张东红,等.赞比亚卢弗里安弧构造带再活化的证据:锆石和磷灰石裂变径迹年代学[J].地球科学,2018,43(6):1 850-1 860.REN Junping,WANG Jie,ZHANG Donghong,et al.Reactivation of Lufilian Arc in Zambia:Zircon and apatite fission track analysis[J].Earth Science,2018,43(6):1 850-1 860(in Chinese).
[19]CASTAING C.Post-Pan-African tectonic evolution of south Malawi in relation to the Karroo and recent east African rift systems[J].Tectonophysics,1991,191:55-73.
[20]GOSCOMBE B,ARMSTRONG R,BARTON J M.Geology of the Chewore Inliers,Zimbabwe:Constraining the Mesoproterozoic to Palaeozoic evolution of the Zambezi Belt[J].Journal of African Earth Sciences,2000,30(3):589-627.
[21]FRITZ H,ABDELSALAM M,ALI K A,et al.Orogen styles in the east African Orogen:A review of the Neoproterozoic to Cambrian tectonic evolution[J].Journal of African Earth Sciences,2013,86:65-106.
[22]THOMAS R J,VONVEH M W,MCCOURT S.The tectonic evolution of southern Africa:An overview[J].Journal of African Earth Sciences,1993,16(1/2):5-24.
[23]HAACK U,GOHN E,KLEIN J A.Rb/Sr ages of granitic rocks along the middle reaches of the Omaruru river and the timing of orogenetic events in the Damara Belt(Namibia)[J].Contrib Mineral Petrol,1980,74:349-360.
[24]BROWN R,SUMMERFIELD M,GLEADOW A,et al.Intracontinental deformation in southern Africa during the Late Cretaceous[J].Journal of African Earth Sciences,2014,100:20-41.
[25]HAEST M,MUCHEZ P.Stratiform and veintype deposits in the Pan-African orogen in central and southern Africa:Evidence for Multiphase Mineralisation[J].Geologica Belgica,2011,14(1-2):23-44.
[26]DEYNOUX M,AFFATON P,TROMPETTE R,et al.Pan-African tectonic evolution and glacial events registered in Neoproterozoic to Cambrian cratonic and foreland basins of West Africa[J].Journal of African Earth Sciences,2006,46:397-426.
[27]GUIRAUD R,BOSWORTH W,THIERRY J,et al.Phanerozoic geological evolution of Northern and Central Africa:An overview[J].Journal of African Earth Sciences,2005,43:83-143.
[28]CARR I D.Second-order sequence stratigraphy of the Palaeozoic of north Africa[J].Journal of Petroleum Geology,2002,25:259-280.
[29]VEEVERS J J.Gondwanaland from 650-500Ma assembly through 320 Ma merger in Pangea to185-100 Ma breakup:Supercontinental tectonics via stratigraphy and radiometric dating[J].Earth-Science Reviews,2004,68:1-132.
[30]陈廷愚.地球旋转膨胀与冈瓦纳古陆裂解[J].地球学报,2005,26(3):195-202.CHEN Tingyu.The expansion of the rotating earth and the breakup of Gondwanaland[J].Acta Geoscientica Sinica,2005,26(3):195-202(in Chinese).
[2]任军平,王杰,古阿雷,等.赞比亚卢弗里安弧地区矿产资源研究现状及找矿潜力分析[J].中国矿业,2017,26(11):139-144.REN Junping,WANG Jie,GU Alei,et al.Research on the status and prospecting potential of mineral resources in Lufilian Arc,Zambia[J].China Mining Magazine,2017,26(11):139-144(in Chinese).
[3] REN Junping,WANG Jie,ZUO Libo,et al.Zircon U-Pb and biotite 40 Ar/39 Ar geochronology from the Anzan emerald deposit in Zambia[J].Ore Geology Reviews,2017,91:612-619.
[4]任军平,左立波,许康康,等.赞比亚北部班韦乌卢地块演化及矿产资源研究现状[J].地质论评,2016,62(4):979-996.REN Junping,ZUO Libo,XU Kangkang,et al.Geodynamic evolution and mineral resources present research in Bangweulu Block,Northern Zambia[J].Geological Review,2016,62(4):979-996(in Chinese).
[5] UNRUG R. The mid-Proterozoic Mporokoso group of northern Zambia:Stratigraphy,sedimentationand regional position[J].Precambrian Research,1984,24:99-121.
[6] ANDREWS-SPEED C P.Gold-bearing fluvial and associated tidalmarine sediments of Proterozoic age in the Mporokoso Basin, Northern Zambia[J].Sedimentary Geology,1986,48:193-222.
[7] ANDREWS-SPEED C P.The mid-Proterozoic Mporokoso basin,Northern Zambia:Sequence stratigraphy,tectonic setting and potential for gold and uranium mineralisation[J].Precambrian Research,1989,44:1-17.
[8] de WAELE B,LIEGEOIS J P,NEMCHIN A A,et al.Isotopic and geochemical evidence of Proterozoic episodic crustal reworking within the irumide belt of south-central Africa,the southern metacratonic boundary of an Archaean Bangweulu Craton[J].Precambrian Research,2006,148:225-256.
[9]袁万明,张雪亭,董金泉,等.东昆仑隆升作用的裂变径迹研究[J].原子能科学技术,2004,38(2):165-168.YUAN Wanming,ZHANG Xueting,DONG Jinquan,et al.Apatite fission track evidence on the uplifting of Eastern Kunlun Mountains[J].Atomic Energy Science and Technology,2004,38(2):165-168(in Chinese).
[10]沈传波,梅廉夫,汤济广,等.大巴山逆冲推覆带构造扩展变形的年代学制约[J].原子能科学技术,2008,42(6):574-576.SHEN Chuanbo,MEI Lianfu,TANG Jiguang,et al. Geochronology evidences for tectonic deformation of Dabashan fold-thrust belt in central China[J].Atomic Energy Science and Technology,2008,42(6):574-576(in Chinese).
[11]王珂,袁万明,冯星,等.东昆仑埃坑地区磷灰石裂变径迹年代学及构造意义[J].原子能科学技术,2018,52(1):186-192.WANG Ke,YUAN Wanming,FENG Xing,et al.Apatite fission track thermochronology and tectonic significance in Aikeng area,east Kunlun mountains[J].Atomic Energy Science and Technology,2018,52(1):186-192(in Chinese).
[12]YAMADA R,TAGAMI T,NISHIMURA S,et al.Annealing kinetics of fission tracks in zircon:An experimental study[J].Chemical Geology,1995,122(1-4):249-258.
[13]赵文菊,袁万明,刘海涛,等.从裂变径迹分析新疆阿尔泰南部地区构造活动与古地形的变化[J].原子能科学技术,2013,47(8):1 458-1 467.ZHAO Wenju,YUAN Wanming,LIU Haitao,et al.Apatite fission track analysis on tectonic activities and paleotopography in southern Altai region,Xinjiang,China[J].Atomic Energy Science and Technology,2013,47(8):1 458-1 467(in Chinese).
[14]DONELICK R A,MILLER D S.Enhanced tint fission track densities in low spontaneous track density apatites using 252 Cf-derived fission fragment tracks:A model and experimental observations[J].Nuclear Tracks and Radiation Measurements,1991,18(3):301-307.
[15]GALBRAITH R F.On statistical models of fission track counts[J].Mathematical Geosciences,1981,13(6):471-478.
[16]MARK T B.Probability density plot for fissiontrack grain-age samples[J].Radiation Measurement,1996,26(5):663-676.
[17]EGLINGER A,VANDERHAEGHE O,ANDRE-MAYER A S,et al.Tectono-metamorphic evolution of the internal zone of the Pan-African Lufilian orogenic belt(Zambia):Implications for crustal reworking and syn-orogenic uranium mineralizations[J].Lithos,2016,240-243:167-188.
[18]任军平,王杰,张东红,等.赞比亚卢弗里安弧构造带再活化的证据:锆石和磷灰石裂变径迹年代学[J].地球科学,2018,43(6):1 850-1 860.REN Junping,WANG Jie,ZHANG Donghong,et al.Reactivation of Lufilian Arc in Zambia:Zircon and apatite fission track analysis[J].Earth Science,2018,43(6):1 850-1 860(in Chinese).
[19]CASTAING C.Post-Pan-African tectonic evolution of south Malawi in relation to the Karroo and recent east African rift systems[J].Tectonophysics,1991,191:55-73.
[20]GOSCOMBE B,ARMSTRONG R,BARTON J M.Geology of the Chewore Inliers,Zimbabwe:Constraining the Mesoproterozoic to Palaeozoic evolution of the Zambezi Belt[J].Journal of African Earth Sciences,2000,30(3):589-627.
[21]FRITZ H,ABDELSALAM M,ALI K A,et al.Orogen styles in the east African Orogen:A review of the Neoproterozoic to Cambrian tectonic evolution[J].Journal of African Earth Sciences,2013,86:65-106.
[22]THOMAS R J,VONVEH M W,MCCOURT S.The tectonic evolution of southern Africa:An overview[J].Journal of African Earth Sciences,1993,16(1/2):5-24.
[23]HAACK U,GOHN E,KLEIN J A.Rb/Sr ages of granitic rocks along the middle reaches of the Omaruru river and the timing of orogenetic events in the Damara Belt(Namibia)[J].Contrib Mineral Petrol,1980,74:349-360.
[24]BROWN R,SUMMERFIELD M,GLEADOW A,et al.Intracontinental deformation in southern Africa during the Late Cretaceous[J].Journal of African Earth Sciences,2014,100:20-41.
[25]HAEST M,MUCHEZ P.Stratiform and veintype deposits in the Pan-African orogen in central and southern Africa:Evidence for Multiphase Mineralisation[J].Geologica Belgica,2011,14(1-2):23-44.
[26]DEYNOUX M,AFFATON P,TROMPETTE R,et al.Pan-African tectonic evolution and glacial events registered in Neoproterozoic to Cambrian cratonic and foreland basins of West Africa[J].Journal of African Earth Sciences,2006,46:397-426.
[27]GUIRAUD R,BOSWORTH W,THIERRY J,et al.Phanerozoic geological evolution of Northern and Central Africa:An overview[J].Journal of African Earth Sciences,2005,43:83-143.
[28]CARR I D.Second-order sequence stratigraphy of the Palaeozoic of north Africa[J].Journal of Petroleum Geology,2002,25:259-280.
[29]VEEVERS J J.Gondwanaland from 650-500Ma assembly through 320 Ma merger in Pangea to185-100 Ma breakup:Supercontinental tectonics via stratigraphy and radiometric dating[J].Earth-Science Reviews,2004,68:1-132.
[30]陈廷愚.地球旋转膨胀与冈瓦纳古陆裂解[J].地球学报,2005,26(3):195-202.CHEN Tingyu.The expansion of the rotating earth and the breakup of Gondwanaland[J].Acta Geoscientica Sinica,2005,26(3):195-202(in Chinese).