Geochemistry and Implications of Clastic Sedimentary Rocks from the Northern Margin of Yangtze Craton
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摘要: 通过系统研究扬子克拉通北缘西乡-碑坝小区后太古代变质沉积岩的主量元素、微量元素和Nd同位素组成, 得出如下结论: (1) 扬子北缘中、晚元古代三花石组杂砂岩的εNd(t), 分别为+2.72和+0.69, TDM分别为1.40Ga和1.57Ga, 与扬子北缘同时期西乡群火山岩具有相近的Nd同位素组成, 扬子克拉通北缘新元古代存在的岛弧物质控制着该区中、晚元古代沉积物源的地球化学组成, 后河群碎屑物质对火地垭群沉积岩有一定的影响; (2) 扬子克拉通北缘古生代沉积物源区以再旋回沉积物源为主, 并随时间变化对再旋回沉积物源的接受逐渐加强, 沉积源区的长英质物质逐渐增多, 分异程度越来越高; 西乡-碑坝小区从寒武纪-志留纪沉积物源很可能是扬子克拉通基底崆岭群和基性火山岩等风化剥蚀后混合的产物, 本区从晚泥盆世开始, 其沉积物源区与秦岭群片麻岩的风化剥蚀有明显的关系; (3) 扬子北缘西乡-碑坝小区从晚二叠世到早侏罗世碎屑沉积岩的εNd(t) 比早古生代碎屑沉积岩的明显偏大, 结合微量元素数据分析, 这与晚二叠世峨眉山玄武岩的多次喷发(火山灰) 和风化剥蚀作用有关.Abstract: This paper presents Sm-Nd and geochemical data on fine-grained sediments of the north margin from the Yangtze craton, China. Systematic research leads to the following conclusions: (1) Nd isotope composition of the clastic sedimentary rocks from the Middle-Upper Proterozoic has the εNd(t) values of +2.72 to +0.69, with the Nd model ages of 1.40 Ga and 1.57 Ga, which corresponds to that of the contemporaneous volcanic rocks from Xixiang Group. It indicates that the arc materials from the Proterozoic control the geochemical composition of main provenances of the Middle-Upper Proterozoic sedimentary rocks. (2) The probable provenances of the Paleozoic sedimentary rocks are dominantly the recycled products of Proterozoic crust as indicated by the decrease of the εNd(t) with the time. The sedimentary rocks from the Cambrian-Silurian were derived ultimately from a polycyclic mixture of the old continental crust materials from the Kongling strata and arc materials from the Proterozoic volcanic in the north margin of the Yangtze craton. The derivation is markedly of sources relatively more felsic extreme weathering. The geochemical and isotopic data indicate that the provenance of Devonian terrain has changed with the progressively increasing proportions of materials from the Qinling complex by erosion. (3) The more prominent increase in the εNd(t) values of the Upper Permian formation probably reflects the significant incorporation of the mantle-derived materials. The comparison between the data of trace element and the data of EMS indicates that the dust of volcano from EMS was related to the Late Permian strata during the Late Permian when the volcanism, represented by Emeishan flood basalts (251-258) in the south-western margin of the Yangtze block was extremely active.
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图 1 扬子克拉通北缘西乡-碑坝地区区域地质略图(高山, 1989)
1.西乡群; 2.后河群、火地娅群; 3.震旦纪-显生宙沉积岩; 4.基性-超基性岩; 5.英云闪长岩、奥长花岗岩; 6.偏碱性或碱性花岗岩类; 7.断层
Fig. 1. Generalized geological map of Xixiang-Beiba subunit
图 2 扬子北缘西乡-碑坝小区沉积岩Al2O3- (CaO*+Na2O) -K2O三角图(Nesbitt and Young, 1989)
图中a线表示风化趋势; b线表示钾质交代趋势; c线表示风化线; 黑色圆点表示平均页岩组成; 斜线花圆点表示上地壳组成
Fig. 2. Ternary plot of Al2O3- (CaO*+Na2O) -K2O for the Xixiang-Beiba metasediments
图 3 西乡-碑坝小区中晚元古代(a) 和显生宙(b) 碎屑沉积岩稀土元素配分曲线
Fig. 3. Chondrite-normalized REE diagram of clastic sediments for the Middle-Upper Proterozoic (a) and the Phanerozoic (b) from Xixiang-Beiba subunit
图 4 扬子克拉通西乡-碑坝小区沉积岩εNd (t) 随时间(t) 演化图
图中新元古火山岩包括二郎坪群火山岩(张宗清等, 1994), 耀岭河群火山岩(黄萱和吴利仁, 1990), 西乡群火山岩, 毛堂群(待刊); 佛坪群和秦岭群包括佛坪群黑云石榴片麻岩(王居里和张国伟, 1999), 秦岭群蛇尾黑云石榴片麻岩和斜长透灰石岩(张宗清等, 1994), 陡岭群变质碎屑沉积岩(沈洁等, 1997); 后河群包括奥长花岗岩和英云闪长岩(凌文黎, 1994), 鱼洞子群黑云斜长片麻岩(张宏飞等, 1997); 崆岭群为奥长花岗岩和英云闪长岩(马大铨等, 1997; Gao et al., 2001); 其余为本文数据, 根据沉积岩地层年龄计算样品的εNd (t), 由于部分地层还没有准确的年龄限制, 因此本文所用沉积年龄是近似值, 计算参数: (143Nd/144Nd) CHUR (0) =0.512 638, (147Sm/144Nd) CHUR (0) =0.196 7
Fig. 4. εNd (t) versus t for the sediments from Xixiang-Beiba subunit, Yangtze craton
图 5 扬子克拉通北缘西乡-碑坝小区沉积岩与秦岭群杂砂岩微量元素对比
图中秦岭群杂砂岩据高山(1989);西乡-碑坝小区碎屑沉积岩据表 1
Fig. 5. Comparison of average trace elements contents of sediments between the Xixiang-Beiba subunit and Qinling terrain
表 1 扬子克拉通西乡-碑坝小区和高川小区碎屑沉积岩主量元素(%) 和微量元素含量(10-6)
Table 1. Concentration of trace elements of clastic sediment from Xixiang-Beiba subunit
表 2 南秦岭和扬子克拉通各小区碎屑沉积岩及部分火山岩Sm-Nd同位素数据
Table 2. Sm-Nd isotopic composition of clastic sediment from Xixiang-Beiba subunit
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[1] Chen, J. F., Zhou, T. X., Xing, F. M., et al., 1989. The sediment source and Nd isotopic composition of low-grade metamorphic rocks and sediments from South Anhui. Chinese Sci. Bull. , 20: 1572-1574 (in Chinese). [2] Chung, S. L., Jahn, B. M., 1995. Plume-lithosphere interactionin generation of the Emeishan flood basalts at the Permian-Triassic boundary. Geology, 23 (10): 889-892. doi: 10.1130/0091-7613(1995)023<0889:PLIIGO>2.3.CO;2 [3] Courtillon, V., Jaupart, C., Manighetti, I., et al., 1999. On causal links between flood basalts and continental breakup. Earth Planet. Sci. Lett. , 166: 177-195. doi: 10.1016/S0012-821X(98)00282-9 [4] Editor Group of Shaanxi Regional Strata, Bureau of Geologyand Mineral Resources of shaanxi Province, 1989. Regional strata table of northwest area of China—Fascicleof Shaanxi Province. Geological Publishing House, Beijing, 1-258 (in Chinese). [5] Gao, S., 1989. Structure, composition and evolution of the continental crust inthe Qinling orogenic belt andits adjacent North China and Yangtze cratons (Dissertation). China University of Geosciences, Wuhan (in Chinese with English abstract). [6] Gao, S., Lin, W. L., Qiu, Y. M., et al., 1999. Contrasting geochemical and Sm-Nd isotopic compositions of Archean metasediments from the Kongling high-grade terrain of the Yangtze craton: Evidence for cratonic evolution and redistribution of REE during crustal anatexis. Geochim. Cosmochim. Acta, 63: 2071-2088. doi: 10.1016/S0016-7037(99)00153-2 [7] Gao, S., Qiu, Y. M., Ling, W. L., et al., 2001. SHRI MP single zircon U-Pb dating of the Kongling high-grade metamorphic terrain: Evidence for < 3.2Ga old continental crust in the Yangtze craton. Sci. in China (Series D), 44 (4): 326-335. doi: 10.1007/BF02907103 [8] Gao, S., Zhang, B. R., Gu, X. M., et al., 1995. SilurianDevonian provenance changes of South Qinling basins: I mplications of cacretion of Yangtze (South China) to the North China cratons. Tectonophysics, 250: 183-197. doi: 10.1016/0040-1951(95)00051-5 [9] Gao, S., Zhang, B. R., Luo, T. C., et. al., 1992. Chemical composition of the continental crust in the Qinling orogenic belt andits adjacent North China and Yangtze cratons. Geochim. Cosmochim. Acta, 56: 3933-3950. doi: 10.1016/0016-7037(92)90007-6 [10] Gao, S., Zhang, B. R., Xie, Q. L., et al., 1991. Average chemical compositions of Post-Archean sedimentary and volcanic rocks from the Qinling orogenic belt andits adjacent North China and Yangtze cratons. Chem. Geol. , 92: 261-236. doi: 10.1016/0009-2541(91)90074-2 [11] Gao, S., Zhou, L., Ling, W. L., et al., 2005. Age and geochemistry of volcanic rocks of Angou Group at the Archean-Proterozoic boundary. Earth Science—Journal of China University of Geosciences, 30 (3): 259-263 (in Chinese with English abstract). [12] Goldstein, S. L., O'Nions, R. K., Hamilton, P. J., 1984. A Sm-Nd isotopic study of at mospheric dusts and particulates from major river systems. Earth Planet. Sci. Lett. , 70: 221-236. doi: 10.1016/0012-821X(84)90007-4 [13] Huang, X., Wu, L. R., 1990. Nd-Sr isotopic characteristics of granitoids from Shaanxi Province and their significance for tectonic evolution. Acta Petrologica Sinica, 6 (2): -11 (in Chinese with English abstract). [14] Li, J. S., Cao, X. Z., Yang, J. L., 1994. Phanerobiotic ancient marine basin and its environment of Qinling belt. Geological Publishing House, Beijing, 1-206 (in Chinese). [15] Li, S. G., Liu, D. L., Chen, Y. Z., et al., 1994. Neodymium isotopic compositions of continental crust in the northern margin of Yangtze block and its tectonic implications. Geochimica, 23 (Suppl. ): 10-17 (in Chinese with English abstract). [16] Li, S. G., Sun, W. D., Zhang, G. W., et al., 1996. Chronology and geochemistry of metavolcanic rocks from Heigouxia valley in the Mian-Lue tectonic zone, South Qinling—Evidence for a Paleozoic oceanic basin and its close time. Sci. in China (Series D), 39 (3): 301-310. [17] Li, X. H., McCulloch, M. T., 1996. Ndisotopic evolution of sediments from the southern margin of the Yangtze block and its tectonic significance. Acta Petrologica Sinica, 12 (3): 359-370 (in Chinese with English abstract). [18] Ling, W. L., 1994. Isotopic study on the Precambrian tectonic features and upper mantle evolution of Yangtze craton (Dissertation). China University of Geosciences, Wuhan (in Chinese with English abstract). [19] Ling, W. L., Gao, S., Ouyang, J. P., et al., 2002. Time and tectonic setting of the Xixiang Group: Constraints from the zircon U-Pb geochronology and geochemistry. Sci. in China (Series D), 45 (9): 818-831. doi: 10.1007/BF02879516 [20] Ma, D. Q., Li, Z. C., Xiao, Z. F., 1997. The constitute, geochronology and geologic evolution of the Kongling complex, West Hubei. Acta Geoscientia Sinica, 18 (3): 233-241 (in Chinese with English abstract). [21] Nesbitt, H. W., Young, G. M., 1989. Formation and diagenesis of weathering profiles. Journal of Geology, 97: 129-147. doi: 10.1086/629290 [22] Niu, Z. J., Xu, A. W., Duan, Q. F., et al., 2000. Origin and enrichment of seleniumin Permian strata in the northern part of Jianshi, Hubei. Regional Geology of China, 19 (4): 396-401 (in Chinese with English abstract). [23] Peucat, J. J., Vidal, P. B., Griffiths, J., et al., 1988. Sr, Nd and Pbisotopic systematics in the Archeanlowto highgrade transition zone of southern Indian: Syn-accretion vs. post-accretion granulites. J. Geol. , 97: 537-550. [24] Shen, J., Zhang, Z. Q., Liu, D. Y., 1997. Sm-Nd, Rb-Sr, 40Ar/39Ar, 207Pb/206Pb age of the Douling metamorphic complex from eastern Qinling orogenic belt. Acta Geoscientia Sinica, 18 (3): 248-254 (in Chinese with English abstract). [25] Taylor, R. S., McLennan, S. M., 1985. The continental crust: Its composition and evolution. Blackwell, London. [26] Wang, J. L., Zhang, G. W., 1999. Geological and geochemical features of the cover rock series of Foping dome, Qinling orogenic belt. Journal of Northwest University (Natural Science Edition), 29 (5): 417-421 (in Chinese with English abstract). [27] Xu, Y. G., Chung, S. L., Jahn, B. M., et al., 2001. Petrologic and geochemical constraints on the petrogenesis of Permian-Triassic Emeishan flood basalts in southwestern China. Lithos, 58: 145-168. doi: 10.1016/S0024-4937(01)00055-X [28] Xu, Y. G., Zhong, S. L., 2001. The Emeishan large igneous province: Evidence for mantle plume activity and melting conditions. Geochimica, 30 (1): 1-9 (in Chinese with English abstract). [29] Zhang, B. R., Luo, T. C., Gao, S., et al., 1990. Geochemistry evolution of the lithosphere in the Qinling-Dabashan characteristics and region, and their geological significance. In: Zhang, B. R., et al., eds., Contribution to regional geochemistry of Qinling and Dabashan Mountains. China University of Geosciences Press, Wuhan (in Chinese). [30] Zhang, B. R., Luo, T. C., Gao, S., et al., 1994. Geochemical study of the lithosphere, tectonism and metallogenesis in the Qinling-Dabashan region. China University of Geosciences Press, Wuhan (in Chinese with English abstract). [31] Zhang, G. W., Zhang, B. R., Yuan, X. C., et al., 2001. Qinling orogenic belt and continental dynamics. Science Press, Beijing (in Chinese). [32] Zhang, H. F., Jin, L. L., Zhang, L., et al., 2006. Pb and Nd isotopic compositions of basement and granitoid in the Qilianshan: Constraints on tectonic affinity. Earth Science—Journal of China University of Geosciences, 31 (1): 59-65 (in Chinese with English abstract). [33] Zhang, H. F., Zhang, B. R., Ling, W. L., et al., 1997. Late Proterozoic crustal accretion of South Qinling: Nd isotopic study from granitic rocks. Geochimica, 26 (5): 16-24 (in Chinese with English abstract). [34] Zhang, H. F., Zhao, Z. D., Luo, T. C., et al., 1995. Crustal growth and lower crust nature of North Qinling: Study of Sm-Ndisotopic model ages. Acta Petrologica Sinica, 11 (2): 160-170 (in Chinese with English abstract). [35] Zhang, Z. Q., Liu, D. Y., Fu, G. M., 1994. Study on the isotopic chronology of metamorphic strata in North Qinling. Geological Publishing House, Beijing (in Chinese). [36] Zhou, M. F., John, M., Xie, Y. S., et al., 2002. A temporal link between the Emeishan large igneous province (SW China) and the end-Guadalupian mass extinction. Earth Planet. Sci. Lett. , 196: 113-122. doi: 10.1016/S0012-821X(01)00608-2 [37] 陈江峰, 周泰禧, 邢凤鸣, 等, 1989. 皖南浅变质岩和沉积岩的钕同位素组成及沉积物物源区. 科学通报, 201572-1574. https://www.cnki.com.cn/Article/CJFDTOTAL-KXTB198920015.htm [38] 高山, 1989. 秦岭造山带及其邻区大陆地壳结构、成分与演化的地球化学研究[博士学位论文]. 武汉: 中国地质大学. [39] 高山, 周炼, 凌文黎, 等, 2005. 华北克拉通南缘太古-元古宙界线安沟群火山岩的年龄及地球化学. 地球科学———中国地质大学学报, 30 (3): 259-263. https://www.cnki.com.cn/Article/CJFDTOTAL-DQKX200503001.htm [40] 黄萱, 吴利仁, 1990. 陕西地区岩浆岩Nd, Sr同位素特征及其与大地构造发展的关系. 岩石学报, 6 (2): 1-11. doi: 10.3321/j.issn:1000-0569.1990.02.001 [41] 李晋僧, 曹宣泽, 杨家禄, 1994. 秦岭显生宙古海盆和演化. 北京: 地质出版社, 1-206. [42] 李曙光, 刘德良, 陈移之, 等, 1994. 扬子陆块北缘地壳的钕同位素组成及其构造意义. 地球化学, 23 (增刊): 10-17. https://www.cnki.com.cn/Article/CJFDTOTAL-DQHX4S1.001.htm [43] 李献华, McCulloch, M. T., 1996. 扬子南缘沉积岩的Nd同位素演化及其大地构造意义. 岩石学报, 12 (3) 359-370. https://www.cnki.com.cn/Article/CJFDTOTAL-YSXB603.000.htm [44] 凌文黎, 1994. 扬子克拉通北缘前寒武纪古大地构造性质及演化的同位素地球化学研究[博士学位论文]. 中国地质大学. [45] 马大铨, 李志昌, 肖志发, 1997. 鄂西崆岭杂岩的组成、时代及地质演化. 地球学报, 18 (3): 233-241. https://www.cnki.com.cn/Article/CJFDTOTAL-DQXB703.001.htm [46] 牛志军, 徐安武, 段其发, 等, 2000. 湖北建始北部二叠纪地层硒的来源与富集. 中国区域地质, 19 (4): 396-401. doi: 10.3969/j.issn.1671-2552.2000.04.010 [47] 陕西省地质矿产局, 1989. 陕西省区域地质志. 北京: 地质出版社, 1-258. [48] 沈洁, 张宗清, 刘敦一, 1997. 东秦岭陡岭群变质杂岩Sm-Nd, Rb-Sr, 40Ar/39Ar, 207Pb/206Pb年龄. 地球学报, 18 (3): 248-254. https://www.cnki.com.cn/Article/CJFDTOTAL-DQXB703.003.htm [49] 王居里, 张国伟, 1999. 秦岭佛坪穹隆盖层岩系的地质和地球化学特征. 西北大学学报(自然科学版), 29 (5): 417-421. https://www.cnki.com.cn/Article/CJFDTOTAL-XBDZ199905013.htm [50] 徐义刚, 钟孙霖, 2001. 峨眉山火山成岩省: 地幔柱活动的证据及其熔融条件. 地球化学, 30 (1): 1-9. https://www.cnki.com.cn/Article/CJFDTOTAL-DQHX200101001.htm [51] 张本仁, 骆庭川, 高山, 等, 1990. 秦巴地区岩石圈地球化学特征和演化及其地质意义. 见: 张本仁, 等, 1990. 秦岭区域地球化学文集. 武汉: 中国地质大学出版社. [52] 张本仁, 骆庭川, 高山, 等, 1994. 秦巴岩石圈构造及成矿规律地球化学研究. 武汉: 中国地质大学出版社. [53] 张国伟, 张本仁, 袁学诚, 等, 2001. 秦岭造山带与大陆动力学. 北京: 科学出版社. [54] 张宏飞, 靳兰兰, 张利, 等, 2006. 基底岩系和花岗岩类Pb-Nd同位素组成限制祁连山带的构造属性. 地球科学———中国地质大学学报, 31 (1): 59-65. https://www.cnki.com.cn/Article/CJFDTOTAL-DQKX200601008.htm [55] 张宏飞, 张本仁, 凌文黎, 等, 1997. 南秦岭新元古代地壳增生事件: 花岗质岩石钕同位素示踪. 地球化学, 26 (5): 16-24. https://www.cnki.com.cn/Article/CJFDTOTAL-DQHX199705001.htm [56] 张宏飞, 赵志丹, 骆庭川, 等, 1995. 从岩石Sm-Nd同位素模式年龄论北秦岭地壳增生和深部地壳性质. 岩石学报, 11 (2): 160-170. https://www.cnki.com.cn/Article/CJFDTOTAL-YSXB199502005.htm [57] 张宗清, 刘敦一, 付国民, 1994. 北秦岭变质地层同位素年代研究. 北京: 地质出版社. -
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