四川盆地北部早白垩世剑门关组泥质岩地球化学特征及其地质意义
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摘要
早白垩世剑门关组是研究四川盆地北部沉积环境演化的良好地层,对该地层开展系统的地球化学研究,对探讨四川盆地北部早白垩世剑门关组物源区性质、构造背景、古风化作用及古环境具有重要意义。系统分析了剑门关组泥质岩主量、微量和稀土元素地球化学特征,发现早白垩世剑门关组泥质岩富CaO、MgO,贫Al_2O_3、Fe_2O_3、K_2O、Na_2O、TiO_2、P_2O_5、MnO,富Cr、Cs、V,贫Sr、Nb、U、Hf,稀土元素总量为(164.96～234.35)×10~(-6),轻、重稀土元素比值为11.77～15.87,轻、重稀土元素分馏程度高,轻稀土元素相对富集,具弱的正Eu异常。综合分析认为:剑门关组为同一物源的近物源再旋回沉积岩;源岩为沉积岩,可能富含斜长石、重晶石等富Eu矿物;源岩在沉积前经历了中等程度的化学风化作用,并发生了钾交代作用;剑门关组沉积期为温暖、湿润的气候,物源区具有由活动大陆边缘向大陆岛弧转化的特征。
The Early Cretaceous Jianmenguan Formation is a good formation to study the sedimentary environment evolution in Northern Sichuan Basin. The systematical study on its geochemical characteristics is significantly important for studying the provenance, tectonic background, ancient weathering and paleoenvironment of Early cretaceous Jianmenguan Formation. In this paper, the geochemical characteristics of major elements, trace elements and rare earth elements(REE) of the argillaceous rocks of Jianmenguan Formation were systemically analyzed. The results show that the argillaceous rocks of Jianmenguan Formation are rich in CaO,MgO, lack Al_2O_3,Fe_2O_3,K_2O,Na_2O,TiO_2,P_2O_5,MnO, are rich in Cr, Cs, V, and lack Sr, Nb, U, Hf. The total amount of REE(∑REE) ranges from 164.96×10~(-6) to 234.35×10~(-6). LREE/HREE is in the range of 11.77～15.87. The fractionation between LREE and HREE is obvious, and LREE content is higher than HREE, with a weak positive Eu anomaly. Based on the analyses above, Jianmenguan Formation is recycling sedimentary rocks from the same sources. Its source rocks are sedimentary rocks, and it may be rich in europium-rich minerals such as plagioclase and barite. The source rocks underwent moderate chemical weathering before sedimentation and K-metasomatisim during the weathering process. The climate during the sedimentary period of Jianmenguan Formation was warm and humid. Tectonic evolution characteristics of the source area appeared to have a transformation from the continental margin to the continental island arc.
The Early Cretaceous Jianmenguan Formation is a good formation to study the sedimentary environment evolution in Northern Sichuan Basin. The systematical study on its geochemical characteristics is significantly important for studying the provenance, tectonic background, ancient weathering and paleoenvironment of Early cretaceous Jianmenguan Formation. In this paper, the geochemical characteristics of major elements, trace elements and rare earth elements(REE) of the argillaceous rocks of Jianmenguan Formation were systemically analyzed. The results show that the argillaceous rocks of Jianmenguan Formation are rich in CaO,MgO, lack Al_2O_3,Fe_2O_3,K_2O,Na_2O,TiO_2,P_2O_5,MnO, are rich in Cr, Cs, V, and lack Sr, Nb, U, Hf. The total amount of REE(∑REE) ranges from 164.96×10~(-6) to 234.35×10~(-6). LREE/HREE is in the range of 11.77～15.87. The fractionation between LREE and HREE is obvious, and LREE content is higher than HREE, with a weak positive Eu anomaly. Based on the analyses above, Jianmenguan Formation is recycling sedimentary rocks from the same sources. Its source rocks are sedimentary rocks, and it may be rich in europium-rich minerals such as plagioclase and barite. The source rocks underwent moderate chemical weathering before sedimentation and K-metasomatisim during the weathering process. The climate during the sedimentary period of Jianmenguan Formation was warm and humid. Tectonic evolution characteristics of the source area appeared to have a transformation from the continental margin to the continental island arc.
引文
[1] Cullers R L,Basu A,Suttner L J.Geochemical signature of provenance in sand-size material in soils and stream sediments near the Tobacco Root batholith,Montana,U.S.A.[J].Chem Geol,1988,70(4):335-348.
[2] Bhatia M R,Crook K A W.Trace element characteristics of grayw-ackes and tectonic setting discrimination of sedimentary basins[J].Contrib Mineral Petrol,1986,92(2):181-193.
[3] Taylor S R,McLennan S M.The Continental Crust:Its Composition and Evolution[M].Oxford:Blackwell Scientific Publication,1985.
[4] 白宪洲,文龙,王玉婷,等.四川省西昌盆地上三叠统白果湾组地球化学特征及其意义[J].中国地质调查,2017,4(2):51-58.
[5] McLennan S M.Rare earth elements in sedimentary rocks:influence of provenance and sedimentary processes[J].Rev Mineral Geochem,1989,21(1):169-200.
[6] Condie K C.Chemical composition and evolution of the upper continental crust:Contrasting results from surface samples and shales[J].Chem Geol,1993,104(1/2/3/4):1-37.
[7] 陈发景,汪新文,陈昭年.前陆盆地分析[M].北京:地质出版社,2007.
[8] 郭正吾,邓康龄,韩永辉,等.四川盆地形成与演化[M].北京:地质出版社,1996.
[9] 陈发景,汪新文,张光亚,等.中国中、新生代前陆盆地的构造特征和地球动力学[J].地球科学:中国地质大学学报,1996,21(4):366-372.
[10] 林滨,高连舜,杨桂生,等.川北白垩系剑门关组冲积相与铀矿聚集条件[J].四川地质学报,1982(2):18-19.
[11] 刘宝珺,余光明,林文球,等.四川南江地区下白垩统剑门关组冲积相地层剖面的数学模拟[J].成都地质学院学报,1982(2):29-32.
[12] 杨帅,谢小平,李冰,等.四川省剑门关区晚侏罗—早白垩世沉积体系的数学模拟[J].重庆理工大学学报(自然科学版),2017,31(7):133-139.
[13] 顾家裕,张兴阳.中国西部陆内前陆盆地沉积特征与层序格架[J].沉积学报,2005,23(2):187-193.
[14] 刘和甫,梁慧社,蔡立国,等.川西龙门山冲断系构造样式与前陆盆地演化[J].地质学报,1994,68(2):101-118.
[15] 罗志立.扬子古板块的形成及其对中国南方地壳发展的影响[J].地质科学,1979,14(2):127-138.
[16] 邓康龄.四川盆地形成演化与油气勘探领域[J].天然气工业,1992,12(5):7-12.
[17] 童崇光.四川盆地构造演化与油气聚集[M].北京:地质出版社,1992.
[18] 郑荣才,李国晖,戴朝成,等.四川类前陆盆地盆-山耦合系统和沉积学响应[J].地质学报,2012,86(1):170-180.
[19] 国家地质实验测试中心.GB/T 14506—2010硅酸盐岩石化学分析方法[S].北京:中国标准出版社,2011.
[20] Wronkiewicz D J,Condie K C.Geochemistry of Archean shales from the Witwatersrand Supergroup,South Africa:Source-area weathering and provenance[J].Geochim Cosmochim Acta,1987,51(9):2401-2416.
[21] Cox R,Lowe D R,Cullers R L.The influence of sediment recycling and basement composition on evolution of mudrock chemistry in the southwestern United States[J].Geochim Cosmochim Acta,1995,59(14):2919-2940.
[22] Girty G H,Ridge D L,Knaack C,et al.Provenance and depositional setting of Paleozoic chert and argillite,Sierra Nevada,California[J].J Sediment Res,1996,66(1):107-118.
[23] Wronkiewicz D J,Condie K C.Geochemistry and provenance of sediments from the Pongola Supergroup,South Africa:Evidence for a 3.0-Ga-old continental craton[J].Geochim Cosmochim Acta,1989,53(7):1537-1549.
[24] Cullers R L.The controls on the major and trace element variation of shales,siltstones,and sandstones of Pennsylvanian-Permian age from uplifted continental blocks in Colorado to platform sediment in Kansas,USA[J].Geochim Cosmochim Acta,1994,58(22):4955-4972.
[25] Long X P,Sun M,Yuan C,et al.Early Paleozoic sedimentary record of the Chinese Altai:Implications for its tectonic evolu-tion[J].Sediment Geol,2008,208(3/4):88-100.
[26] 许德如,马驰,Nonna B C,等.海南岛北西部邦溪地区奥陶纪火山-碎屑沉积岩岩石学、矿物学和地球化学:源区及构造环境暗示[J].地球化学,2007,36(1):11-26.
[27] Bhatia M R,Taylor S R.Trace-element geochemistry and sedimentary provinces:A study from the Tasman Geosyncline,Austra-lia[J].Chem Geol,1981,33(1/4):115-125.
[28] 伊海生,林金辉,赵西西,等.西藏高原沱沱河盆地渐新世—中新世湖相碳酸盐岩稀土元素地球化学特征与正铕异常成因初探[J].沉积学报,2008,26(1):1-10.
[29] McLennan S M,Hemming S,McDaniel D K,et al.Geochemical approaches to sedimentation,provenance,and tectonics[M]//Johnsson M J,Basu A.GSA Special Papers.Geological Society of America,1993,284:21-40.
[30] Floyd P A,Leveridge B E.Tectonic environment of the Devonian Gramscatho basin,south Cornwall:Framework mode and geoche-mical evidence from turbiditic sandstones[J].J Geol Soc,1987,144(4):531-542.
[31] Bhatia M R.Composition and classification of Paleozoic flysch mudrocks of eastern Australia:Implications in provenance and tectonic setting interpretation[J].Sediment Geol,1984,41(2/4):249-268.
[32] Roser B P,Korsch R J.Determination of tectonic setting of sandstone-mudstone suites using SiO2 content and K2O/Na2O ratio[J].J Geol,1986,94(5):635-650.
[33] Bhatia M R,Crook K A W.Trace element characteristics of graywackes and tectonic setting discrimination of sedimentary basins[J].Contrib Mineral Petrol,1986,92(2):181-193.
[34] Fedo C M,Nesbitt H W,Young G M.Unraveling the effects of potassium metasomatism in sedimentary rocks and paleosols,with implications for paleoweathering conditions and provenance[J].Geology,1995,23(10):921-924.
[2] Bhatia M R,Crook K A W.Trace element characteristics of grayw-ackes and tectonic setting discrimination of sedimentary basins[J].Contrib Mineral Petrol,1986,92(2):181-193.
[3] Taylor S R,McLennan S M.The Continental Crust:Its Composition and Evolution[M].Oxford:Blackwell Scientific Publication,1985.
[4] 白宪洲,文龙,王玉婷,等.四川省西昌盆地上三叠统白果湾组地球化学特征及其意义[J].中国地质调查,2017,4(2):51-58.
[5] McLennan S M.Rare earth elements in sedimentary rocks:influence of provenance and sedimentary processes[J].Rev Mineral Geochem,1989,21(1):169-200.
[6] Condie K C.Chemical composition and evolution of the upper continental crust:Contrasting results from surface samples and shales[J].Chem Geol,1993,104(1/2/3/4):1-37.
[7] 陈发景,汪新文,陈昭年.前陆盆地分析[M].北京:地质出版社,2007.
[8] 郭正吾,邓康龄,韩永辉,等.四川盆地形成与演化[M].北京:地质出版社,1996.
[9] 陈发景,汪新文,张光亚,等.中国中、新生代前陆盆地的构造特征和地球动力学[J].地球科学:中国地质大学学报,1996,21(4):366-372.
[10] 林滨,高连舜,杨桂生,等.川北白垩系剑门关组冲积相与铀矿聚集条件[J].四川地质学报,1982(2):18-19.
[11] 刘宝珺,余光明,林文球,等.四川南江地区下白垩统剑门关组冲积相地层剖面的数学模拟[J].成都地质学院学报,1982(2):29-32.
[12] 杨帅,谢小平,李冰,等.四川省剑门关区晚侏罗—早白垩世沉积体系的数学模拟[J].重庆理工大学学报(自然科学版),2017,31(7):133-139.
[13] 顾家裕,张兴阳.中国西部陆内前陆盆地沉积特征与层序格架[J].沉积学报,2005,23(2):187-193.
[14] 刘和甫,梁慧社,蔡立国,等.川西龙门山冲断系构造样式与前陆盆地演化[J].地质学报,1994,68(2):101-118.
[15] 罗志立.扬子古板块的形成及其对中国南方地壳发展的影响[J].地质科学,1979,14(2):127-138.
[16] 邓康龄.四川盆地形成演化与油气勘探领域[J].天然气工业,1992,12(5):7-12.
[17] 童崇光.四川盆地构造演化与油气聚集[M].北京:地质出版社,1992.
[18] 郑荣才,李国晖,戴朝成,等.四川类前陆盆地盆-山耦合系统和沉积学响应[J].地质学报,2012,86(1):170-180.
[19] 国家地质实验测试中心.GB/T 14506—2010硅酸盐岩石化学分析方法[S].北京:中国标准出版社,2011.
[20] Wronkiewicz D J,Condie K C.Geochemistry of Archean shales from the Witwatersrand Supergroup,South Africa:Source-area weathering and provenance[J].Geochim Cosmochim Acta,1987,51(9):2401-2416.
[21] Cox R,Lowe D R,Cullers R L.The influence of sediment recycling and basement composition on evolution of mudrock chemistry in the southwestern United States[J].Geochim Cosmochim Acta,1995,59(14):2919-2940.
[22] Girty G H,Ridge D L,Knaack C,et al.Provenance and depositional setting of Paleozoic chert and argillite,Sierra Nevada,California[J].J Sediment Res,1996,66(1):107-118.
[23] Wronkiewicz D J,Condie K C.Geochemistry and provenance of sediments from the Pongola Supergroup,South Africa:Evidence for a 3.0-Ga-old continental craton[J].Geochim Cosmochim Acta,1989,53(7):1537-1549.
[24] Cullers R L.The controls on the major and trace element variation of shales,siltstones,and sandstones of Pennsylvanian-Permian age from uplifted continental blocks in Colorado to platform sediment in Kansas,USA[J].Geochim Cosmochim Acta,1994,58(22):4955-4972.
[25] Long X P,Sun M,Yuan C,et al.Early Paleozoic sedimentary record of the Chinese Altai:Implications for its tectonic evolu-tion[J].Sediment Geol,2008,208(3/4):88-100.
[26] 许德如,马驰,Nonna B C,等.海南岛北西部邦溪地区奥陶纪火山-碎屑沉积岩岩石学、矿物学和地球化学:源区及构造环境暗示[J].地球化学,2007,36(1):11-26.
[27] Bhatia M R,Taylor S R.Trace-element geochemistry and sedimentary provinces:A study from the Tasman Geosyncline,Austra-lia[J].Chem Geol,1981,33(1/4):115-125.
[28] 伊海生,林金辉,赵西西,等.西藏高原沱沱河盆地渐新世—中新世湖相碳酸盐岩稀土元素地球化学特征与正铕异常成因初探[J].沉积学报,2008,26(1):1-10.
[29] McLennan S M,Hemming S,McDaniel D K,et al.Geochemical approaches to sedimentation,provenance,and tectonics[M]//Johnsson M J,Basu A.GSA Special Papers.Geological Society of America,1993,284:21-40.
[30] Floyd P A,Leveridge B E.Tectonic environment of the Devonian Gramscatho basin,south Cornwall:Framework mode and geoche-mical evidence from turbiditic sandstones[J].J Geol Soc,1987,144(4):531-542.
[31] Bhatia M R.Composition and classification of Paleozoic flysch mudrocks of eastern Australia:Implications in provenance and tectonic setting interpretation[J].Sediment Geol,1984,41(2/4):249-268.
[32] Roser B P,Korsch R J.Determination of tectonic setting of sandstone-mudstone suites using SiO2 content and K2O/Na2O ratio[J].J Geol,1986,94(5):635-650.
[33] Bhatia M R,Crook K A W.Trace element characteristics of graywackes and tectonic setting discrimination of sedimentary basins[J].Contrib Mineral Petrol,1986,92(2):181-193.
[34] Fedo C M,Nesbitt H W,Young G M.Unraveling the effects of potassium metasomatism in sedimentary rocks and paleosols,with implications for paleoweathering conditions and provenance[J].Geology,1995,23(10):921-924.