西准噶尔萨吾尔山一带吉木乃组流纹岩LA-ICP-MS锆石U-Pb年代学及地质意义
|
摘要
吉木乃组是西准萨吾尔山地区地质时代久存争议的地层,也是火山岩占地层总厚度比例最高的火山-沉积地层。采用同位素年龄标定火山岩准确的地质时代,是解决本组时代分歧的有效手段。吉木乃组顶部新发现的流纹岩中获得(304.1±2.5)Ma(n=15,MSWD=1.07)的LA-ICP-MS锆石U-Pb年龄,确认成岩时代为晚石炭世晚期(大致相当于卡西莫夫期)。结合前人在本组下部层位采集的植物化石,限定吉木乃组时代为晚石炭世(大致为巴什基尔期—卡西莫夫期)。流纹岩同位素定年准确约束了吉木乃组地质时代上限,为区域地层格架的建立和地层对比提供了可靠的时代依据。
The geological age of the Jimunai Formation has long been controversial in the Saur Mountain of West Junggar.It is also a volcanic-sedimentary stratum with the highest proportion of volcanic rocks to the total thickness of strata,and thus,it is an effective method to resolve the age divergences of the Jimunai Formation using accurate geological age of the volcanic rocks. LA-ICP-MS dating was used to determine the zircons from the newly discovered rhyolite of the upper Jimunai Formation,which yielded zircon U-Pb age of 304.1±2.5 Ma(n=15,MSWD=1.07),corresponding to the end of the Late Carboniferous. In view of predecessors′ fossil information,we suggest that the formation age of Jimunai Formation is Bashkirian to Kasimovian of Late Carboniferous.Isotopic dating of rhyolite accurately constrained the minimum age of the Jimunai Formation,and provided new chronological evidence for the establishment of regional stratigraphic framework and stratigraphic correlation.
The geological age of the Jimunai Formation has long been controversial in the Saur Mountain of West Junggar.It is also a volcanic-sedimentary stratum with the highest proportion of volcanic rocks to the total thickness of strata,and thus,it is an effective method to resolve the age divergences of the Jimunai Formation using accurate geological age of the volcanic rocks. LA-ICP-MS dating was used to determine the zircons from the newly discovered rhyolite of the upper Jimunai Formation,which yielded zircon U-Pb age of 304.1±2.5 Ma(n=15,MSWD=1.07),corresponding to the end of the Late Carboniferous. In view of predecessors′ fossil information,we suggest that the formation age of Jimunai Formation is Bashkirian to Kasimovian of Late Carboniferous.Isotopic dating of rhyolite accurately constrained the minimum age of the Jimunai Formation,and provided new chronological evidence for the establishment of regional stratigraphic framework and stratigraphic correlation.
引文
[1]新疆维吾尔自治区地质矿产局.新疆维吾尔自治区区域地质志[M].北京:地质出版社,1993,1-841.
[2]新疆地质矿产局地质矿产研究所.新疆古生界(下)[M].乌鲁木齐:新疆人民出版社,1991,1-482.
[3]新疆维吾尔自治区地质矿产局.新疆维吾尔自治区岩石地层[M].武汉:中国地质大学出版社,1999,1-430.
[4]Feng Y M,Coleman R G,Tilton G,et al.Tectonic evolution of the West Junggar region,Xinjiang,China[J].Tectonics,1989,8(4):729-752.
[5]Xiao W J,Han C M,Yuan C,et al.Middle Cambrian to Permian subduction-related accretionary orogenesis of Northern Xinjiang,NW China:Implications for the tectonic evolution of central Asia[J].Journal of Asian Earth Sciences,2008,32(2-4):102-117.
[6]Geng H Y,Sun M,Yuan C,et al.Geochemical and geochronological study of early Carboniferous volcanic rocks from the West Junggar:Petrogenesis and tectonic implications[J].Journal of Asian Earth Sciences,2011,42(5):854-866.
[7]Windley B F,Xiao W J.Ridge subduction and slab windows in the Central Asian Orogenic Belt:Tectonic implications for the evolution of an accretionary orogen[J].Gondwana Research,2018,61:73-87.
[8]Zhang J E,Xiao W J,Luo J,et al.Collision of the Tacheng block with the Mayile-Barleik-Tangbale accretionary complex in Western Junggar,NW China:Implication for Early-Middle Paleozoic architecture of the western Altaids[J].Journal of Asian Earth Sciences,2018,159:259-278.
[9]Yang G X,Li Y J,Xiao W J,et al.Petrogenesis and tectonic implications of the Middle Silurian volcanic rocks in northern West Junggar,NW China[J].International Geology Review,2014,56(7):869-884.
[10]Zhou T F,Yuan F,Fan Y,et al.Geodynamic significance of the A-type granites in the Sawuer region in west Junggar,Xinjiang:Rock geochemistry and SHRIMP zircon age evidence[J].Science in China(Series D),2006,49(2):113-123.
[11]袁峰,周涛发,杨文平,等.新疆萨吾尔地区两类花岗岩Nd,Sr,Pb,O同位素特征[J].地质学报,2006,80(2):264-272.
[12]Zhou T F,Yuan F,Fan Y,et al.Granites in the Saur region of the west Junggar,Xinjiang Province,China:Geochronological and geochemical characteristics and their geodynamic significance[J].Lithos,2008,106(3-4):191-206.
[13]Chen J F,Han B F,Ji J Q,et al.Zircon U-Pb ages and tectonic implications of Paleozoic plutons in northern West Junggar,North Xinjiang,China[J].Lithos,2010,115(1):137-152.
[14]Deng Y F,Yuan F,Zhou T,et al.Geochemistry and tectonic impli cations of the Early Carboniferous Keketuobie intrusion in the West Junggar foldbelt,NW China[J].Journal of Asian Earth Sci ences,2018,159:142-154.
[15]Yuan F,Deng Y F,Zhou T F,et al.Petrogenesis and timing of emplacement of porphyritic monzonite,dolerite,and basalt associated with the Kuoerzhenkuola Au deposit,Western Junggar,NWChina:Implications for early Carboniferous tectonic setting and Cu-Au mineralization prospectivity[J].International Geology Review,2017,59(9):1154-1174.
[16]周涛发,袁峰,杨文平,等.西准噶尔萨吾尔地区二叠纪火山活动规律[J].中国地质,2006,33(3):553-558.
[17]吴元保,郑永飞.锆石成因矿物学研究及其对U-Pb年龄解释的制约[J].科学通报,2004,49(16):1589-1604.
[18]Sun S S,McDonough W F.Chemical and isotopic systematics of oceanic basalts:Implications for mantle composition and processes[J].Geological Society,Special Publications,1989,42(1):313-345.
[19]赵振华.副矿物微量元素地球化学特征在成岩成矿作用研究中的应用[J].地学前缘,2010,17(1):267-286.
[20]Hoskin P W O,Black L P.Metamorphic zircon formation by solidstate recrystallization of protolith igneous zircon[J].Journal of metamorphic Geology,2000,18(4):423-439.
[21]Compston W,Williams I S,Kirschvink J L,et al.Zircon U-Pb ages for the Early Cambrian time-scale[J].Joumal of Geological Society,1992,149(2):171-184.
(1)新疆地矿局第四地质大队.新疆萨吾尔山托斯特一带1∶5万区域地质调查报告,1998
(1)新疆地矿局第四地质大队.新疆萨吾尔山托斯特一带1∶5万区域地质调查报告,1998
(1)新疆地矿局第四地质大队.新疆萨吾尔山托斯特一带1∶5万区域地质调查报告,1998
[2]新疆地质矿产局地质矿产研究所.新疆古生界(下)[M].乌鲁木齐:新疆人民出版社,1991,1-482.
[3]新疆维吾尔自治区地质矿产局.新疆维吾尔自治区岩石地层[M].武汉:中国地质大学出版社,1999,1-430.
[4]Feng Y M,Coleman R G,Tilton G,et al.Tectonic evolution of the West Junggar region,Xinjiang,China[J].Tectonics,1989,8(4):729-752.
[5]Xiao W J,Han C M,Yuan C,et al.Middle Cambrian to Permian subduction-related accretionary orogenesis of Northern Xinjiang,NW China:Implications for the tectonic evolution of central Asia[J].Journal of Asian Earth Sciences,2008,32(2-4):102-117.
[6]Geng H Y,Sun M,Yuan C,et al.Geochemical and geochronological study of early Carboniferous volcanic rocks from the West Junggar:Petrogenesis and tectonic implications[J].Journal of Asian Earth Sciences,2011,42(5):854-866.
[7]Windley B F,Xiao W J.Ridge subduction and slab windows in the Central Asian Orogenic Belt:Tectonic implications for the evolution of an accretionary orogen[J].Gondwana Research,2018,61:73-87.
[8]Zhang J E,Xiao W J,Luo J,et al.Collision of the Tacheng block with the Mayile-Barleik-Tangbale accretionary complex in Western Junggar,NW China:Implication for Early-Middle Paleozoic architecture of the western Altaids[J].Journal of Asian Earth Sciences,2018,159:259-278.
[9]Yang G X,Li Y J,Xiao W J,et al.Petrogenesis and tectonic implications of the Middle Silurian volcanic rocks in northern West Junggar,NW China[J].International Geology Review,2014,56(7):869-884.
[10]Zhou T F,Yuan F,Fan Y,et al.Geodynamic significance of the A-type granites in the Sawuer region in west Junggar,Xinjiang:Rock geochemistry and SHRIMP zircon age evidence[J].Science in China(Series D),2006,49(2):113-123.
[11]袁峰,周涛发,杨文平,等.新疆萨吾尔地区两类花岗岩Nd,Sr,Pb,O同位素特征[J].地质学报,2006,80(2):264-272.
[12]Zhou T F,Yuan F,Fan Y,et al.Granites in the Saur region of the west Junggar,Xinjiang Province,China:Geochronological and geochemical characteristics and their geodynamic significance[J].Lithos,2008,106(3-4):191-206.
[13]Chen J F,Han B F,Ji J Q,et al.Zircon U-Pb ages and tectonic implications of Paleozoic plutons in northern West Junggar,North Xinjiang,China[J].Lithos,2010,115(1):137-152.
[14]Deng Y F,Yuan F,Zhou T,et al.Geochemistry and tectonic impli cations of the Early Carboniferous Keketuobie intrusion in the West Junggar foldbelt,NW China[J].Journal of Asian Earth Sci ences,2018,159:142-154.
[15]Yuan F,Deng Y F,Zhou T F,et al.Petrogenesis and timing of emplacement of porphyritic monzonite,dolerite,and basalt associated with the Kuoerzhenkuola Au deposit,Western Junggar,NWChina:Implications for early Carboniferous tectonic setting and Cu-Au mineralization prospectivity[J].International Geology Review,2017,59(9):1154-1174.
[16]周涛发,袁峰,杨文平,等.西准噶尔萨吾尔地区二叠纪火山活动规律[J].中国地质,2006,33(3):553-558.
[17]吴元保,郑永飞.锆石成因矿物学研究及其对U-Pb年龄解释的制约[J].科学通报,2004,49(16):1589-1604.
[18]Sun S S,McDonough W F.Chemical and isotopic systematics of oceanic basalts:Implications for mantle composition and processes[J].Geological Society,Special Publications,1989,42(1):313-345.
[19]赵振华.副矿物微量元素地球化学特征在成岩成矿作用研究中的应用[J].地学前缘,2010,17(1):267-286.
[20]Hoskin P W O,Black L P.Metamorphic zircon formation by solidstate recrystallization of protolith igneous zircon[J].Journal of metamorphic Geology,2000,18(4):423-439.
[21]Compston W,Williams I S,Kirschvink J L,et al.Zircon U-Pb ages for the Early Cambrian time-scale[J].Joumal of Geological Society,1992,149(2):171-184.
(1)新疆地矿局第四地质大队.新疆萨吾尔山托斯特一带1∶5万区域地质调查报告,1998
(1)新疆地矿局第四地质大队.新疆萨吾尔山托斯特一带1∶5万区域地质调查报告,1998
(1)新疆地矿局第四地质大队.新疆萨吾尔山托斯特一带1∶5万区域地质调查报告,1998