内蒙古艾力格庙地区二叠纪火山-沉积岩系的层序、时代及其构造意义
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摘要
为了查明兴蒙造山带西段二连-满都拉裂陷盆地的充填过程以及其中火山-沉积岩系的时空分布,对西里庙组开展地层层序和同位素年代学研究,探讨盆地形成的构造背景。实测剖面查明,二叠纪西里庙组地层可分为3段,上段和下段为晶屑凝灰岩及流纹质岩屑晶屑凝灰岩,中段为暗色沉积岩,构成独特的火山-沉积岩系。上段流纹质凝灰岩的锆石~(206)Pb/~(238)U年龄为282±2 Ma,代表形成年龄;中段碎屑岩的两组锆石年龄峰值分别为304 Ma和450 Ma,另有1颗锆石的年龄为870 Ma,分别代表最大沉积年龄、早古生代造山带的形成时代和晚元古代基底的年龄。中段碎屑岩的年代学测试结果表明,西里庙组火山-沉积岩系的形成时代为304～282 Ma,其层位应置于哲斯组之下。西里庙组中段沉积地层碎屑锆石的物源分析结果为从中古生代构造挤压过程向晚古生代构造伸展过程转化的沉积响应提供了证据。
Several rift basins developed in the western part of Xing'an-Mongol orogenic belt during late Paleozoic, in which volcanic-sedimentary series is important to understand the late Paleozoic tectonic evolution, however, there is not a clear space-time distribution of the series. Stratigraphy and geochronology of Xilimiao Formation have been researched to understand the basin filling process and tectonic setting. According to the field sections, Xilimiao Formation can be divided into three segments. Upper and lower segments are composed of crystal tuffs and rhyolitic lithic crystal tuffs, and middle segment are dark sedimentary rocks. The zircon ~(206)Pb/~(238)U age of 282±2 Ma achieved from the rhyolitic tuff of upper segment represents the forming age. The two peak ages of 304 Ma and 450 Ma represent the upper limit of the sedimentary event, the forming age of early Paleozoic orogenic belt, respectively, and the 870 Ma represents the age of Neoproterozoic basement. The data of middle detrital rocks indicate that the forming age of Xilimiao Formation was between 304-282 Ma, older than Zhesi Formation. Provenance of the detrital zircon from the middle Xilimiao Formation provides sedimentary evidence for transform process from compress of the middle Paleozoic orogenic belt to extension of the late Paleozoic rift basin.
Several rift basins developed in the western part of Xing'an-Mongol orogenic belt during late Paleozoic, in which volcanic-sedimentary series is important to understand the late Paleozoic tectonic evolution, however, there is not a clear space-time distribution of the series. Stratigraphy and geochronology of Xilimiao Formation have been researched to understand the basin filling process and tectonic setting. According to the field sections, Xilimiao Formation can be divided into three segments. Upper and lower segments are composed of crystal tuffs and rhyolitic lithic crystal tuffs, and middle segment are dark sedimentary rocks. The zircon ~(206)Pb/~(238)U age of 282±2 Ma achieved from the rhyolitic tuff of upper segment represents the forming age. The two peak ages of 304 Ma and 450 Ma represent the upper limit of the sedimentary event, the forming age of early Paleozoic orogenic belt, respectively, and the 870 Ma represents the age of Neoproterozoic basement. The data of middle detrital rocks indicate that the forming age of Xilimiao Formation was between 304-282 Ma, older than Zhesi Formation. Provenance of the detrital zircon from the middle Xilimiao Formation provides sedimentary evidence for transform process from compress of the middle Paleozoic orogenic belt to extension of the late Paleozoic rift basin.
引文
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[13]徐备,王志伟,张立杨,等.兴蒙陆内造山带.岩石学报,2018,34(10):2819-2844
[14]Xu B,Zhao P,Wang Y Y,et al.The pre-Devonian tectonic framework of Xing’an-Mongolia orogenic belt(XMOB)in north China.Journal of Asian Earch Sciences,2015,97:183-196
[15]Chen Y,Zhang Z C,Li K,et al.Detrital zircon U-Pb ages and Hf isotopes of Permo-Carboniferous sandstones in central Inner Mongolia,China:implications for provenance and tectonic evolution of the southeastern Central Asian Orogenic Belt.Tectonophysics,2016,671:183-201
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[18]徐备,赵盼,鲍庆中,等.兴蒙造山带前中生代构造单元划分初探.岩石学报,2014,30(7):1841-1857
[19]Demoux A,Kroner A,Hegner E,et al.Devonian arcrelated mag-matism in the Tseel terrane of SWMongolia:chronological and geoche mical evidence.Journal of the Geological Society,2009,166:459-471
[20]周印章,韩宝福,徐钊,等.中蒙边界英巴地区元古宙杂岩的时代及其对南戈壁微陆块分布范围的限定.地质通报,2013,32(2/3):319-326
[21]徐备,徐严,栗进,等.内蒙古西部温都尔庙群的时代及其在中亚造山带中的位置.地学前缘,2016,23(6):120-127
[22]李承东,冉皞,赵利刚,等.温都尔庙群锆石的LA-ICP-MS U-Pb年龄以及构造意义.岩石学报,2012,28(11):3705-3714
[23]Sláma J,Kostler J,Condon D J,et al.Ple?ovice-a new natural reference material for U-Pb and Hf isotopic analysis.Chemical Geology,2008,197:111?142
[24]Andersen T,Griffin W L.Lu-Hf and U-Pb isotope systematics of zircons from the Storgangen intrusion,Rogaland Intrusive Complex,SW Norway:implications for the composition and evolution of Precambrian lower crust in the Baltic Shield.Lithos,2004,73(3):271?288
[25]Rubatto D,Hermann J.Zircon formation during fluid circulation in eclogites(Monviso,Western Alps):implications for Zr and Hf budget in subduction zones.Geochimica et Cosmochimica Acta,2003,67(12):2173?2187
[26]邵济安,唐克东,何国琦.内蒙古早二叠世构造古地理的再造.岩石学报,2014,30(7):1858-1866
(1)内蒙古自治区地质局.区域地质调查报告:脑木根幅, 1980
[2]Jahn,Wu B M,Chen F,et al.Granitoids of the Central Asian Orogenic Belt and continental growth in the Phanerozoic.Transactions of the Royal Society of Edinburgh Earth Sciences,2000,91(1/2):181?193
[3]Jahn B M.The Central Asian Orogenic Belt and growth of the continental crust in the Phanerozoic.Geological Society London Special Publications,2004,226(1):73?100
[4]Khain E V,Bibikova E V,Kr?ner A,et al.The most ancient ophiolite of the Central Asian fold belt:U-Pb and Pb-Pb zircon ages for the Dunzhugur Complex,Eastern Sayan,Siberia,and geodynamic implications.Earth&Planetary Science Letters,2002,199(3):311?325
[5]Kr?ner A,Windley B F,Badarch G.Accretionary growth and crust formation in the Central Asian Orogenic Belt and comparison with the ArabianNubian shield.Geological Society of America Memoir,2007,200:181-209
[6]Li J Y.Permian geodynamic setting of Northeast China and adjacent regions:closure of the PaleoAsian Ocean and subduction of the Paleo-Pacific Plate.Journal of Asian Earth Sciences,2006,26(3):207?224
[7]Rytsk E Y,Kovach V P,Kovalenko V I,et al.Structure and evolution of the continental crust in the Baikal fold region.Geotectonics,2007,41(6):440-464
[8]Seng?r A M C,Natal’in B A,Burtman V S.Evolution of the Altaid tectonic collage and Paleozoic crustal growth in Eurasia.Nature,1993,364:299?307
[9]Windley B F,Alexeiev D,Xiao W J,et al.Tectonic models for accretion of the Central Asian Orogenic Belt.Journal of the Geological Society of London,2007,164:31-47
[10]Xiao W J,Windley B F,Hao J,et al.Accretion leading to collision and the Permian Solonker suture,Inner Mongolia,China:termination of the Central Asian Orogenic Belt.Tectonics,2003,22(6):doi:10.1029/2002TC001484
[11]Jian P,Liu D,Kr?ner A,et al.Evolution of a Permian intraoceanic arc-trench system in the Solonker suture zone,Central Asian Orogenic Belt,China and Mongolia.Lithos,2010,118(1/2):169?190
[12]Xu B,Charvet J,Chen Y,et al.Middle Paleozoic convergent orogenic belts in western Inner Mongolia(China):framework,kinematics,geochronology and implications for tectonic evolution of the Central Asian Orogenic Belt.Gondwana Research,2013,23(4):1342-1364
[13]徐备,王志伟,张立杨,等.兴蒙陆内造山带.岩石学报,2018,34(10):2819-2844
[14]Xu B,Zhao P,Wang Y Y,et al.The pre-Devonian tectonic framework of Xing’an-Mongolia orogenic belt(XMOB)in north China.Journal of Asian Earch Sciences,2015,97:183-196
[15]Chen Y,Zhang Z C,Li K,et al.Detrital zircon U-Pb ages and Hf isotopes of Permo-Carboniferous sandstones in central Inner Mongolia,China:implications for provenance and tectonic evolution of the southeastern Central Asian Orogenic Belt.Tectonophysics,2016,671:183-201
[16]Yarmolyuk V V,Kovalenko V I,Sal’nikova E B,et al.U-Pb age of syn-and postmetamorphic granitoids of South Mongolia:evidence for the presence of Grenvillides in the Central Asian Foldbelt.Doklady Earth Sciences,2005,404:986-990
[17]张焱杰,徐备,田英杰,等.兴蒙造山带晚古生代伸展过程:来自二连浩特东北部石炭?二叠系沉积地层的证据.岩石学报,2018,34(10):3083-3100
[18]徐备,赵盼,鲍庆中,等.兴蒙造山带前中生代构造单元划分初探.岩石学报,2014,30(7):1841-1857
[19]Demoux A,Kroner A,Hegner E,et al.Devonian arcrelated mag-matism in the Tseel terrane of SWMongolia:chronological and geoche mical evidence.Journal of the Geological Society,2009,166:459-471
[20]周印章,韩宝福,徐钊,等.中蒙边界英巴地区元古宙杂岩的时代及其对南戈壁微陆块分布范围的限定.地质通报,2013,32(2/3):319-326
[21]徐备,徐严,栗进,等.内蒙古西部温都尔庙群的时代及其在中亚造山带中的位置.地学前缘,2016,23(6):120-127
[22]李承东,冉皞,赵利刚,等.温都尔庙群锆石的LA-ICP-MS U-Pb年龄以及构造意义.岩石学报,2012,28(11):3705-3714
[23]Sláma J,Kostler J,Condon D J,et al.Ple?ovice-a new natural reference material for U-Pb and Hf isotopic analysis.Chemical Geology,2008,197:111?142
[24]Andersen T,Griffin W L.Lu-Hf and U-Pb isotope systematics of zircons from the Storgangen intrusion,Rogaland Intrusive Complex,SW Norway:implications for the composition and evolution of Precambrian lower crust in the Baltic Shield.Lithos,2004,73(3):271?288
[25]Rubatto D,Hermann J.Zircon formation during fluid circulation in eclogites(Monviso,Western Alps):implications for Zr and Hf budget in subduction zones.Geochimica et Cosmochimica Acta,2003,67(12):2173?2187
[26]邵济安,唐克东,何国琦.内蒙古早二叠世构造古地理的再造.岩石学报,2014,30(7):1858-1866
(1)内蒙古自治区地质局.区域地质调查报告:脑木根幅, 1980