华北地台南缘霍邱安阳山地区八公山群地层时代归属(青白口纪):来自碎屑锆石年代学的制约
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摘要
分布于华北地台南缘,霍邱一固始交界安阳山地区的八公山群,由一套碎屑岩和碳酸盐岩组成。最近,人们在碳酸盐岩中发现蜒、珊瑚等化石,确定灰岩时代为晚石炭世。但是,碎屑岩的地质时代仍然没有定论。碎屑岩由粉砂质泥岩、石英砂岩、粉砂岩等组成,厚度大于780m。石英砂岩为中.厚层状,中细粒结构,成分成熟度和结构成熟度高,石英含量高达95%以上,属于滨海一陆棚沉积。应用LA-ICP-MS对石英砂岩中碎屑锆石U-Pb年代学研究表明,样品HQ2106和HQ2204最年轻的碎屑锆石U-Pb年龄分别为860±22.2Ma(YSG),877±22.6Ma(YSG),前者代表了地层的最大沉积年龄,它们也得到锆石年龄加权平均值(YC1σ和YC2σ)的支持。因此,研究区八公山群碎屑岩地层时代属于青白口纪(拉伸纪)。该研究结果将为华北地台南缘前寒武纪地层划分对比以及构造演化历史重塑提供重要依据。
The Bagongshan Group distributed on the Anyangshan area,the border between the Anhui Huoqiu and Henan Gushi,is composed of a suit of detrital rocks and carbonate rocks.Recently,some body fossils such as Boultonia ? sp.,Tabulata etc.have been found in the carbonate rocks,which determine the carbonate rocks belonging to Late Carboniferous.But,the stratigraphy time of the detrital rocks is still up in the air.The detrital rocks consist of silty mudstone,quartz sandstone,and siltstone etc.,with a thickness of over 780 meters.The quartz sandstone is middle-bedded,medium-fine grain of texture,high maturity of composition and texture,quartz contents of which are over 95%,which formed under a near-shore-shelf depositional environment.The goal of this study was to use U-Pb isotope dating of detrital zircons by laser ablation to refine the depositional age.The samples HQ2106 and HQ2204have youngest ages of detrital zircon:860±22.2Ma(YSG) and 877±22.6Ma(YSG) respectively,and the former indicates the maximum age of deposition of the detrital rocks,which is supported by the weighted mean age(YC1σ and YC2σ) of youngest cluster of two or more grain ages.So,the Bagongshan Group detrital rocks in the Anyangshan area should belong to the Qingbaikou(Tonian) of the Neoproterozoic.This result will constrain the division and correlation of the Preeambrian strata and tectonic evolution of the south margin of the North China Block.
The Bagongshan Group distributed on the Anyangshan area,the border between the Anhui Huoqiu and Henan Gushi,is composed of a suit of detrital rocks and carbonate rocks.Recently,some body fossils such as Boultonia ? sp.,Tabulata etc.have been found in the carbonate rocks,which determine the carbonate rocks belonging to Late Carboniferous.But,the stratigraphy time of the detrital rocks is still up in the air.The detrital rocks consist of silty mudstone,quartz sandstone,and siltstone etc.,with a thickness of over 780 meters.The quartz sandstone is middle-bedded,medium-fine grain of texture,high maturity of composition and texture,quartz contents of which are over 95%,which formed under a near-shore-shelf depositional environment.The goal of this study was to use U-Pb isotope dating of detrital zircons by laser ablation to refine the depositional age.The samples HQ2106 and HQ2204have youngest ages of detrital zircon:860±22.2Ma(YSG) and 877±22.6Ma(YSG) respectively,and the former indicates the maximum age of deposition of the detrital rocks,which is supported by the weighted mean age(YC1σ and YC2σ) of youngest cluster of two or more grain ages.So,the Bagongshan Group detrital rocks in the Anyangshan area should belong to the Qingbaikou(Tonian) of the Neoproterozoic.This result will constrain the division and correlation of the Preeambrian strata and tectonic evolution of the south margin of the North China Block.
引文
安徽省地质矿产局.1987.安徽省区域地质志.北京:地质出版社.1—721.Bureau of Geology and Mineral Resource of Anhui Province.1987.Regional Geology of Anhui Province.Beijing:Geological Publishing House.1—721.
安徽省地质矿产局.1997.安徽省岩石地层.武汉:中国地质大学出版社.1—299.Bureau of Geology and Mineral Resource of Anbui Province.1997.Multiple Classification and Correlation on the Stratigraphy of China(34):Stratigraphy(Lithostratic)of Anhui Province.Wuhan:China University of Geosciences Press.1—299.
毕治国,李玉发,汤加富等.1994.皖西自大山群的发现及其地质意义.安徽地质,4(增刊):135—140.Bi Zhiguo,Li Yufa,Tang Jiafu et al.1994.The discovery of the Baidashan Group in West Anhui and its geological significance.Geology of Anhui,4(suppl.):135—140.
李双应,岳书仓,杨建等.2003.皖北新元古代刘老碑组页岩的地球化学特征及其地质意义.地质科学,38(2):241—253.Li Shuangying,Yue Shucang,Yang Jian et al.2003.Geochemical characteristics and implications of Neoproterozoic shales from the Liulaobei Formation in North Anhui.Chinese Journal of Geology,38(2):241—253.
李双应,杨欣,程成等.2014.论皖南地区前寒武纪浅变质岩系地层层序.地层学杂志,38(1):77—94.Li Shuangying,Yang Xin,Cheng Cheng et al.2014.On the stratigraphic sequences of Precambrian weak metamorphic rock series in South Anhui,China.Journal of Stratigraphy,38(1):77—94.
钱迈平,袁训来,阎永奎等.2002.苏皖北部新元古代微生物化石.微体古生物学报,19(4):363—381.Qian Maiping,Yuan Xunlai,Yan Yongkui et al.2002.Neoprnterozoic microfossils from northern Jiangsu and Anhui.Acts Micropalaeontologiea Siniea,19(4):363—381.
汪贵翔.1984.苏皖北部上前寒武系研究.合肥:安徽科学技术出版社.1—209.Wang Guixiang.1984.Research on the Upper Precambrian of Northern Jiangsu and Anhui Province.Hefei:Anhui Science&Technology Publishing House.1—209.
杨杰东,郑文武,王宗哲等.2001.sr、c同位素对苏皖北部上前寒武系时代的界定.地层学杂志,25(1):44—47.Yang Jiedong,Zheng Wenwu,Wang Zengzhe et al.2001.Age determining of the Upper Precambrian system of northern Jiangsu-Anhui by using Sr and C isotopes.Journal of Stratigraphy,25(1):44—47.
杨杰东,郑文武,陶仙聪等.2004.安徽淮南群四顶山组燧石Sm—Nd年龄测定.地质论评,50(4):413—417.Yang Jiedong,Zheng Wenwei,Tao Xiancong et al.2001.The Sm-Nd age of cherts from Sidingshan Formation of the Huainan Group of Anhui Province.Geological Review,50(4):413—417.
尹磊明.1999.论我国新元古代微体浮游植物化石及其生物地层意义.古生物学报,38(2):133—146.Yin Leiming.1999.Neoproterozoic microphytoplanktonic fossils in China and their biostratigraphical implicatian.Acta Palaeontol Sinica,38(2):133—146.
Barbeau J D L,Ducea M N,Gehrels G E et al.2005.U-Pb detrital-zircon geochronology of northern Salinian basement and cover rocks.Geological Society of America Bulletin,117(3—4):466—481.
Chen F K,Gun J H,Jiang L Let al.2003.Provenance of the Beihuaiyang lower-grade metamorphic zone of the Dabie ultrahighpressure collisional orogen,China:Evidence from zircon ages.Journal of Asian Earth Sciences,22(4):343—352
Dickinson W R and Gehrels G E.2009.Use of U-Pb ages of detrital zircons to infer maximum depositional ages of strata:A test against a Colorado Plateau Mesozoic database.Earth and Planetary Science Letters,288(1—2):115—125.
Jones J V,Connelly J N,Karlstrom K E et al.2009.Age,provenance,and tectonic setting of Paleoproterozoic quartzite successions in the southwestern United States.Geological Society of America Bulletin,121(1—2):247—264.
Li S Y,Ji Z F,Wang Set al.2014.Discovery of Late Carboniferous strata and their tectonic significance in the southern margin of the North China Block(Huoqiu and Gushi areas).Chinese Science Bulletin,59(7):645—650.
Liu Y Q,Gao L Z,Liu Y X et al.2006.Zircon U-Pb dating for the earliest Neoproterozoic mafic magmatism in the southern margin of the North China Block.Chinese Science Bulletin,51(19):2375—2382.
Mclennan S M,Bock B,Compston W et al.2001.Detrital zircon geochronology of Taconlian and Acadian Foreland sedimentary rocks in New England.Journal of Sedimentary Research,71(2):305—317.
Meng Q R,Li S Y and Li R W.2007.Mesozoic evolution of the Hefei Basin in eastern China:Sedimentary response to deformations in the adjacent Dabieshan and along the Tanlu fault.Geological Society of America Bulletin,119(7—8):897—916.
Nelson D R.2001.An assessment of the determination of depositional ages for Precambfian clasfic sedimentary recks by U-Pb dating of detrital zircons.Sedimentary Geology,141—142:37—60.
Rainbird R H,Hamilton M A and Young G M.2001.Detrital zircon geochronology and provenance of the Torridonian,NW Scotland.Journal of the Geological Society,158:15—27.
Ross G M,Parrish P R,Winston D.1992.Provenance and U-Pb geochronology of the Mesoproterozoic Belt Supergroup(northwestern United States):Implications for age of depositional and pre-Panthalassa plate reconstructions.Earth and Planetary ScieNce Letters,113(1—2):57—76.
Tucker R T,Roberts E M,Hu Y et al.2013.Detrital zircon age constraints for the Winton Formation,Queensland:Contextualizing Australia's Late Cretaceous dinosaur faunas.Gondwana Research,24(2):767—779.
Yang D B,Xu W L,Xu Y G et al.2012.U-Pb ages and Hf isotope data from detrital zircons in the eoproterozoic sandstones of northern Jiangsu and southern Liaoning Provinces,China:Implications for the Late Precambrian evolution of the southeastern North China Craton.Precambrian Research,216—219:162—176.
安徽省地质矿产局.1997.安徽省岩石地层.武汉:中国地质大学出版社.1—299.Bureau of Geology and Mineral Resource of Anbui Province.1997.Multiple Classification and Correlation on the Stratigraphy of China(34):Stratigraphy(Lithostratic)of Anhui Province.Wuhan:China University of Geosciences Press.1—299.
毕治国,李玉发,汤加富等.1994.皖西自大山群的发现及其地质意义.安徽地质,4(增刊):135—140.Bi Zhiguo,Li Yufa,Tang Jiafu et al.1994.The discovery of the Baidashan Group in West Anhui and its geological significance.Geology of Anhui,4(suppl.):135—140.
李双应,岳书仓,杨建等.2003.皖北新元古代刘老碑组页岩的地球化学特征及其地质意义.地质科学,38(2):241—253.Li Shuangying,Yue Shucang,Yang Jian et al.2003.Geochemical characteristics and implications of Neoproterozoic shales from the Liulaobei Formation in North Anhui.Chinese Journal of Geology,38(2):241—253.
李双应,杨欣,程成等.2014.论皖南地区前寒武纪浅变质岩系地层层序.地层学杂志,38(1):77—94.Li Shuangying,Yang Xin,Cheng Cheng et al.2014.On the stratigraphic sequences of Precambrian weak metamorphic rock series in South Anhui,China.Journal of Stratigraphy,38(1):77—94.
钱迈平,袁训来,阎永奎等.2002.苏皖北部新元古代微生物化石.微体古生物学报,19(4):363—381.Qian Maiping,Yuan Xunlai,Yan Yongkui et al.2002.Neoprnterozoic microfossils from northern Jiangsu and Anhui.Acts Micropalaeontologiea Siniea,19(4):363—381.
汪贵翔.1984.苏皖北部上前寒武系研究.合肥:安徽科学技术出版社.1—209.Wang Guixiang.1984.Research on the Upper Precambrian of Northern Jiangsu and Anhui Province.Hefei:Anhui Science&Technology Publishing House.1—209.
杨杰东,郑文武,王宗哲等.2001.sr、c同位素对苏皖北部上前寒武系时代的界定.地层学杂志,25(1):44—47.Yang Jiedong,Zheng Wenwu,Wang Zengzhe et al.2001.Age determining of the Upper Precambrian system of northern Jiangsu-Anhui by using Sr and C isotopes.Journal of Stratigraphy,25(1):44—47.
杨杰东,郑文武,陶仙聪等.2004.安徽淮南群四顶山组燧石Sm—Nd年龄测定.地质论评,50(4):413—417.Yang Jiedong,Zheng Wenwei,Tao Xiancong et al.2001.The Sm-Nd age of cherts from Sidingshan Formation of the Huainan Group of Anhui Province.Geological Review,50(4):413—417.
尹磊明.1999.论我国新元古代微体浮游植物化石及其生物地层意义.古生物学报,38(2):133—146.Yin Leiming.1999.Neoproterozoic microphytoplanktonic fossils in China and their biostratigraphical implicatian.Acta Palaeontol Sinica,38(2):133—146.
Barbeau J D L,Ducea M N,Gehrels G E et al.2005.U-Pb detrital-zircon geochronology of northern Salinian basement and cover rocks.Geological Society of America Bulletin,117(3—4):466—481.
Chen F K,Gun J H,Jiang L Let al.2003.Provenance of the Beihuaiyang lower-grade metamorphic zone of the Dabie ultrahighpressure collisional orogen,China:Evidence from zircon ages.Journal of Asian Earth Sciences,22(4):343—352
Dickinson W R and Gehrels G E.2009.Use of U-Pb ages of detrital zircons to infer maximum depositional ages of strata:A test against a Colorado Plateau Mesozoic database.Earth and Planetary Science Letters,288(1—2):115—125.
Jones J V,Connelly J N,Karlstrom K E et al.2009.Age,provenance,and tectonic setting of Paleoproterozoic quartzite successions in the southwestern United States.Geological Society of America Bulletin,121(1—2):247—264.
Li S Y,Ji Z F,Wang Set al.2014.Discovery of Late Carboniferous strata and their tectonic significance in the southern margin of the North China Block(Huoqiu and Gushi areas).Chinese Science Bulletin,59(7):645—650.
Liu Y Q,Gao L Z,Liu Y X et al.2006.Zircon U-Pb dating for the earliest Neoproterozoic mafic magmatism in the southern margin of the North China Block.Chinese Science Bulletin,51(19):2375—2382.
Mclennan S M,Bock B,Compston W et al.2001.Detrital zircon geochronology of Taconlian and Acadian Foreland sedimentary rocks in New England.Journal of Sedimentary Research,71(2):305—317.
Meng Q R,Li S Y and Li R W.2007.Mesozoic evolution of the Hefei Basin in eastern China:Sedimentary response to deformations in the adjacent Dabieshan and along the Tanlu fault.Geological Society of America Bulletin,119(7—8):897—916.
Nelson D R.2001.An assessment of the determination of depositional ages for Precambfian clasfic sedimentary recks by U-Pb dating of detrital zircons.Sedimentary Geology,141—142:37—60.
Rainbird R H,Hamilton M A and Young G M.2001.Detrital zircon geochronology and provenance of the Torridonian,NW Scotland.Journal of the Geological Society,158:15—27.
Ross G M,Parrish P R,Winston D.1992.Provenance and U-Pb geochronology of the Mesoproterozoic Belt Supergroup(northwestern United States):Implications for age of depositional and pre-Panthalassa plate reconstructions.Earth and Planetary ScieNce Letters,113(1—2):57—76.
Tucker R T,Roberts E M,Hu Y et al.2013.Detrital zircon age constraints for the Winton Formation,Queensland:Contextualizing Australia's Late Cretaceous dinosaur faunas.Gondwana Research,24(2):767—779.
Yang D B,Xu W L,Xu Y G et al.2012.U-Pb ages and Hf isotope data from detrital zircons in the eoproterozoic sandstones of northern Jiangsu and southern Liaoning Provinces,China:Implications for the Late Precambrian evolution of the southeastern North China Craton.Precambrian Research,216—219:162—176.