桐柏-大别造山带高压变质单元岩石Pb同位素组成

张利; 钟增球; 张宏飞; 王林森

桐柏-大别造山带高压变质单元岩石Pb同位素组成

张利^{1, 2,},
钟增球^{1, 2},
张宏飞^{1, 2},
王林森^{1, 2}

1.
中国地质大学地质过程与矿产资源国家重点实验室, 湖北武汉 430074
2.
中国地质大学地球科学学院, 湖北武汉 430074

基金项目:

国家自然科学基金项目 40372094

国家重大基础研究发展规划项目 G1999075506

中国地质大学(武汉)优秀青年教师资助计划项目 CUGQNL0327

详细信息

作者简介:
张利(1970-), 女, 副教授, 主要从事同位素地球化学和造山带化学动力学研究. E-mail:lizhang@cug.edu.cn

中图分类号: P597
计量
- 文章访问数: 3666
- HTML全文浏览量: 113
- PDF下载量: 5
- 被引次数: 0
出版历程
- 刊出日期: 2005-11-25

Pb Isotope Compositions of Metamorphic Rocks from High-Pressure Unit in Tongbai-Dabie Orogenic Belt

ZHANG Li^{1, 2
,},
ZHONG Zeng-qiu^{1, 2},
ZHANG Hong-fei^{1, 2},
WANG Lin-sen^{1, 2}

1.
State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China
2.
Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074, China

摘要

摘要: 铅同位素组成对于研究构造分区与演化、块体相互作用以及识别地壳中不同块体的上、下层次关系等具有重要意义.桐柏-大别造山带高压变质单元岩石的全岩Pb同位素组成研究表明, 在该造山带不同区段, 高压变质岩系二云钠长片麻岩与榴辉岩具有相似的Pb同位素组成, 表现为上部地壳高放射成因的Pb同位素组成特征, 其中Pb同位素组成为: ²⁰⁶Pb/²⁰⁴Pb=17.599~18.310, ²⁰⁷Pb/²⁰⁴Pb=15.318~15.615, ²⁰⁸Pb/²⁰⁴Pb=37.968~39.143.大别和桐柏地区高压变质岩系Pb同位素组成的一致性进一步证明了大别地区与桐柏地区的高压变质岩系是可以相连的, 它们应属于同一构造单元.高压变质岩系Pb同位素比值总体高于超高压变质岩系, 验证了桐柏-大别造山带扬子俯冲陆壳从下部岩系到上部岩系Pb同位素比值呈规律增长这一Pb同位素化学特征.侵入于高压变质岩系中的面理化(含榴)花岗岩, 其Pb同位素组成与高压变质岩系相比相对较低, 而与超高压变质岩系及其中的面理化(含榴)花岗岩相似, 为: ²⁰⁶Pb/²⁰⁴Pb=17.128~17.434, ²⁰⁷Pb/²⁰⁴Pb=15.313~15.422, ²⁰⁸Pb/²⁰⁴Pb=37.631~38.122.这表明高压变质岩系和超高压变质岩系中的面理化(含榴)花岗岩具有相同的岩浆来源.结合面理化(含榴)花岗岩具有A型花岗岩的地球化学特征分析, 它们的岩浆物质可能来自超高压变质岩折返至中下地壳的减压退变和部分熔融.
- PB同位素组成 /
- 面理化(含榴)花岗岩 /
- 高压变质岩系 /
- 桐柏-大别造山带
Abstract: Pb isotope compositions play an important role in tectonic division and evolution, block interaction and identifying different block relations in the crust. Our study shows that Pb isotope compositions of the high-pressure (HP) metamorphic rocks in different parts of Tongbai-Dabie orogenic belt, consisting of two-mica albite gneisses and eclogites, are similar and characterized by upper crustal Pb isotope compositions. They have ²⁰⁶pb/²⁰⁴Pb= 17. 599 - 18. 310, ²⁰⁷pb/²⁰⁴Pb= 15. 318 - 15. 615, ²⁰⁸pb/²⁰⁴Pb=37. 968 - 39. 143. The Pb isotope compositions of the HP metamorphic rocks both in Tongbai and Dahie areas are consistent. It is suggested that the HP metamorphic rocks both in Tongbai and Dabie areas belong to the same lithotectonic unit. In general, the Pb isotope compositions of the HP metamorphic rocks are higher than those of the ultrahigh pressure (UHP) metamorphic rocks. It is evident that the Pb isotope compositions of the rocks from the subducted Yangtze continental crust in Tongbai-Dabie orogenic belt show a regular variation from lower crust to upper crust, from lower radiogenic abundances in the lower crust to higher abundances in the upper crust. The foliated garnet-bearing granites, in-truded into the HP metamorphic rocks in different parts of the orogenic belt have similar Pb isotope compositions. They have ²⁰⁶pb/²⁰⁴Pb= 17. 128 - 17. 434, ²⁰⁷pb/²⁰⁴Pb= 15. 313 - 15. 422 and ²⁰⁸pb/²⁰⁴Pb= 37. 631 - 38. 122, which are obviously different from the compositions of the HP metamorphic rocks but similar to those of the UHP metamorphic rocks and the foliated garnet-bearing granites in the UHP metamorphic rocks. This shows that the granites both in the HP and UHP metamorphic rocks have a common magma source. The foliated garnet-bearing granites have the geochemical characteristics of A-type granites, suggesting that the magma of these granites in the UHP and HP metamorphic rocks were derived from the partial melting of the retro-metamorphosed UHP metamorphic rocks exhumed into the middle to lower crust.
- Pb isotope compositions /
- foliated garnet-bearing granites /
- high-pressure metamorphic rocks /
- Tongbai-Dabie orogenic belt

HTML全文

图 1 桐柏-大别地区地质简图(Zhang et al., 2002)

1.大别核部杂岩；2.超高压变质岩系；3.高压变质岩系；4.蓝闪绿片岩变质岩系；5.北淮阳块体；6.桐柏杂岩；7.中生代花岗岩；8.断层；9. 地质界限；空心方框为片麻岩样品点；实心方框为榴辉岩样品点；实心三角为面理化(含榴)花岗岩样品点

Fig. 1. Simplified geological map of the Tongbai-Dabie area

下载: 全尺寸图片幻灯片

图 2 桐柏-大别地区Pb同位素垂直构造剖面

Fig. 2. Vertical tectonic stack in the Tongbai-Dabie area established from variations in Pb isotope

下载: 全尺寸图片幻灯片

图 3 Pb同位素组成

1.超高压变质岩系及其中面理化(含榴)花岗岩(空心三角)；2.高压变质岩系(实心方框)；3.高压变质岩系中面理化(含榴)花岗岩(实心圆点)；超高压变质岩系Pb同位素数据来自文献张宏飞等(2001)和Zhang et al. (2002)；铅同位素初始比值(²⁰⁶Pb/²⁰⁴Pb)_t、(²⁰⁷Pb/²⁰⁴Pb)_t、(²⁰⁸Pb/²⁰⁴Pb)_t为t = 230 Ma时计算所得

Fig. 3. (²⁰⁶Pb/²⁰⁴Pb)tvs.(²⁰⁷Pb/²⁰⁴Pb)tand (²⁰⁸Pb/²⁰⁴Pb)tdiagrams

下载: 全尺寸图片幻灯片

表 1 桐柏一大别造山带高压变质岩系及其中面理化(含榴)花岗岩Pb同位素组成和U、Th、Pb含量(10^-6)

Table 1. Pbisotope compositons and U,Th and Pb contets (10^-6) of the HP metanorphic rocks and folated garnet-bearing granites in the Tongbar-Dabie orogenic belt

参考文献(48)

[1]	Aitcheson, S.J., Harmon, R.S., Moorbath, S., et al., 1995. Pb isotopes define basement domains of the Altiplano, central Andes. Geology, 23: 555 - 558.
[2]	Cheng, Y. Q., Liu, D. Y., Williams, I. S., et al., 2000. SHRIMP U-Pb dating of zircons of a dark-coloured eclogite and a garnet-bearing gneissic-granitic rock from Bixiling, eastern Dabie area. Acta Geologica Sinica, 74: 193 - 205 (in Chinese with English abstract).
[3]	Cong, B.L., Wang, Q.C., 1999. Recent development in study of the Dabie-Sulu UHP rock. Chinese Science Bulletin, 44(12): 1074 - 1088. doi: 10.1007/BF02886130
[4]	Ernst, W. G., Liou, J. G., 1995. Contrasting plate-tectonic styles of Qinling-Dabie-Sulu and Franciscan metamorphic belts. Geology, 23: 353 - 356.
[5]	Hacker, B.R., Wang, X., Eide, E. A., et al., 1996. Qinlin-Dabie ultrahigh-pressure metamorphismin central China. Tectonics, 14: 994 - 1006.
[6]	Hacker, B.R., Ratschbacher, L., Webb, L., 1998. U/Pb zircon ages constrain the architecture of the ultrahighpressure Qinling-Dabie orogen, China. Earth and Planetary Science Letters, 161 (1 - 4): 215 - 236. doi: 10.1016/S0012-821X(98)00152-6
[7]	Hacher, B.R., Ratschbacher, L., Webb, L., et al., 2000. Exhumation of ultrahigh-pressure continental crust in east central China: Late Triassic-Early Jurassic tectonic unroofing. Journal of Geophysical Research, 105: 13339 - 13364. doi: 10.1029/2000JB900039
[8]	Jahn, B.M., 1998. Geochemical andisotopic characteristics of UHP eclogites and ultramafic rocks of the Dabie orogen: Implications for continental subduction and collisional tectonics. In: Hacker, B. R., Liou, J. G., eds., When continents collide: Geodynamics of ultrahigh pressure rocks. Kluwer Academic Publisher, Netherlands, 203 - 239.
[9]	Li, S. G., Li, H. M., Chen, Y. Z., et al., 1997. The UHP metamorphic geochronology of Dabie mountain-Sulu terrain-Ⅱ. Zircon U-Pb isotope system. Science in China (Series D), 27 (3): 200 - 206 (in Chinese).
[10]	Li, S.G., Huang, F., Zhou, H.Y., et al., 2003. U-Pb isotopic compositions of the ultrahigh pressure metamorphic (UHPM) rocks from Shuanghe and gneisses from northern Dabie zone in the Dabie mountains, central China: Constraint on the exhumation mechanism of UHPM rocks. Science in China (Series D), 46(3): 200 -209.
[11]	Liu, F.L., Zhang, Z. M., Xu, Z.Q., 2003. Three-dimensional distribution of ultrahigh-pressure minerals in Sulu terrane. Acta Gologica Sinica, 77 (1): 69 - 84 (in Chinese with English abstract).
[12]	Liu, F.L., Xu, Z. Q., Yang, J.S., et al., 2004. Geochemical characteristics and UHP metamorphism of granitic gneisses in the main drilling hole of Chinese Continental Scientific Drilling Project and its adjacent area. Acta Petrologic Sinica, 20(1): 9 - 26 (in Chinese with English abstract).
[13]	Patino Douce, A.E., McCarty, T.C., 1998. Melting of crustal rocks during continetal collision and subduction. In: Hacker, B. R., Liou, J. G., eds., When continents collide: Geodynamics of ultrahigh pressure rocks. Kluwer Academic Publisher, Netherlands, 27 - 55.
[14]	Suo, S.T., Zhong, Z. Q., You, Z.D., 1999. Location of Triassic tectonic suture bet ween collided Sino-Korean and Yangtze cratons in Dabie-Sulu region, China. J. China Univ. Geosci., 10(4): 281 - 286.
[15]	Suo, S. T., Zhong, Z. Q., You, Z. D., et al., 2001. Postcollisional ductile extensional tectonic framework in the UHP and HP metamorphic belts in the Dabie-Sulu region, China. Acta Geologica Sinica, 75 (2): 151 - 160.
[16]	Tang, J., Zheng, Y.F., Wu, Y.B., et al., 2004. Zircon U-Pb ages and oxygen isotopes of high-grade metamorphic rocks in the eastern part of the Shandong peninsula. Acta Petrologica Sinica, 20 (5): 1039 - 1062 (in Chinese with English abstract).
[17]	Taylor, S. R., McLennan, S. M., 1985. The continental crust: Its composition and evolution. Blackwell Scientific Publication, Oxford, 132.
[18]	Wang, C., Zeng, R., Mooney, W.D., et al., 2000. A crustal model of the ultrahigh-pressure Dabie Shan orogenic belt, China, derived from deep seismic refraction profiling. Journal of Geophysical Research, 105: 10857 - 10869. doi: 10.1029/1999JB900415
[19]	Xu, Q.D., Ouyang, J.P., Zhang, B.R., et al., 2002. Tectonic affinity of Paleozoic stratigraphic slices along the northern margin in Dabie orogen, central China: Evidence from Pb isotope of rocks. Progress in Natural Science, 12(6): 438 - 444.
[20]	Xu, S.T., Okay, A.I., Ji, S.Y., et al., 1992. Diamond from the Dabie Shan metamorphic rocks and its implication for tectonic setting. Science, 256: 80 - 82. doi: 10.1126/science.256.5053.80
[21]	Xu, S. T., Wu, W.P., Su, W., et al., 1998. Meta-granitoid from the high-ultrahigh pressure metamorphic belt in the Dabie mountains and its tectonic significance. Acta Petrologica Sinica, 14 (1): 42 - 59 (in Chinese with English abstract).
[22]	Yang, Q.J., Zhong, Z. Q., 2004. A study on genesis of the garnet-bearing granites in the UHP terrane of DabieSulu orogenic belt, central China. Earth Science—Journal of China University of Geosciences, 29 (2): 169 - 176 (in Chinese with English abstract).
[23]	Yang, Q.J., Zhong, Z.Q., Zhou, H. W., 2003. Geochemistry constrains on rock association of UHP terrane during exhumation. Earth Science—Journal of China University of Geosciences, 28 (3): 241 - 249 (in Chinese with English abstract).
[24]	Zart man, R. E., Doe, B. R., 1981. Plumbotectonics—The model. Tectonophysics, 75: 135 - 162. doi: 10.1016/0040-1951(81)90213-4
[25]	Zhang, H.F., Zhang, B.R., Zhong, Z. Q., et al., 2000. Geochemistry of gneisses from Dabie complex and Tongbai complex in Qinling-Tongbai-Dabie orogenic belt: Implictions for location of Yangtze-Sino-Korean suture. Journal of China University of Geosciences, 11 (4): 392 -405.
[26]	Zhang, H.F., Zhong, Z. Q., Gao, S., et al., 2001. U-Pb zircon age of the foliated garnet-bearing granites in western Dabie mountains, central China. Chinese Science Bulletin, 46(19): 1657 - 1660. doi: 10.1007/BF02900630
[27]	Zhang, H.F., Gao, S., Zhang, B.R., et al., 2001. Pb isotopic study on crustal structure of Dabie mountains, central China. Geochimica, 30 (4): 395 - 401 (in Chinese with English abstract).
[28]	Zhang, H.F., Gao, S., Zhong, Z.Q., et al., 2002. Geochemical and Sr-Nd-Pb isotopic compositions of Cretaceous granitoids: Constraints on tectonic framework and crustal structure of the Dabieshan ultrahigh-pressure metamorphic belt, China. Chemical Geology, 281 - 299.
[29]	Zhang, H.F., Zhang, B. R., Zhang, H.Z., et al., 2003. Pb isotopic geochemical study on the crustal structure of Tongbaishan. Progress in Natural Science, 13 (1): 63 - 68.
[30]	Zhang, L., Zhang, H. F., Zhong, Z. Q., et al., 2003. Geochemical characteristcis of Pb isotope of high-pressure metamorphic rocks and foliated granites from HP unit of Tongbai-Dabie orogenic belt. Journal of China University of Geosciences, 14(4): 321 - 329.
[31]	Zhang, L., Zhong, Z. Q., Zhang, B. R., et al., 2004. Geochemistry and petrogenesis of foliated garnet-bearing granites in the high pressure metamorphic unit of the Tongbai-Dabie orogenic belt. Geochimica, 33 (3): 232 - 242 (in Chinese with English abstract).
[32]	Zhang, L.G., Liu, J.X., Wang, K.F., et al., 1995. Block geology of eastern Asialithosphere—isotope geochemistry and dynamics of upper mantle, basement and granites. Science Press, Beijing, 252 (in Chinese).
[33]	Zheng, Y.F., Gong, B., Zhao, Z.F., et al., 2003. Two types of gneisses associated with eclogite at Shuanghe in the Dabie terrane: Carbon isotope, zircon U-Pb dating and oxygen isotope. Lithos, 70: 321 - 343. doi: 10.1016/S0024-4937(03)00104-X
[34]	Zhong, Z.Q., Suo, S.T., You, Z.D., et al., 2001. Major constituents of the Dabie collisional orogenic belt and partial melting in the ultrahigh-pressure unit. International Geology Review, 43: 226 - 236. doi: 10.1080/00206810109465010
[35]	Zhu, B.Q., 1994. Geochemical evidence for the southern China block being a part of Gondwana. Journal of Souhteast Asian Earth Sciences, 9: 319 - 324. doi: 10.1016/0743-9547(94)90042-6
[36]	Zhu, B. Q., Chang, X. Y., 2001. Geochemical provinces and their boundaries. Advancein Earth Sciences, 16(2): 153 - 162 (in Chinese with English abstract).
[37]	程裕淇, 刘敦一, Williams, I., 等, 2000. 大别山碧溪岭深色片麻岩和片麻状花岗质岩石SHRIMP分析. 地质学报, 74: 193 - 205. doi: 10.3321/j.issn:0001-5717.2000.03.001
[38]	李曙光, 李惠民, 陈移之, 等, 1997. 大别山-苏鲁地体超高压变质年代学, Ⅱ. 锆石U-Pb同位素体系. 中国科学(D辑), 27 (3): 200 - 206. https://www.cnki.com.cn/Article/CJFDTOTAL-JDXK199703001.htm
[39]	刘福来, 张泽明, 许志琴, 2003. 苏鲁地体超高压矿物的三维空间分布. 地质学报, 77 (1): 69 - 84. doi: 10.3321/j.issn:0001-5717.2003.01.009
[40]	刘福来, 许志琴, 杨经绥, 等, 2004. 李天福中国大陆科学钻探工程主孔及周边地区花岗质片麻岩的地球化学性质和超高压变质作用标志的识别. 岩石学报, 20(1): 9 - 26. https://www.cnki.com.cn/Article/CJFDTOTAL-YSXB200401001.htm
[41]	唐俊, 郑永飞, 吴元保, 等, 2004. 胶东地块东部变质岩锆石U-Pb定年和氧同位素研究. 岩石学报, 20 (5): 1039 - 1062. https://www.cnki.com.cn/Article/CJFDTOTAL-YSXB200405004.htm
[42]	徐树桐, 吴维平, 苏文, 等, 1998. 大别山东部榴辉岩带中的变质花岗岩及其大地构造意义. 岩石学报, 14 (1): 42 - 59. https://www.cnki.com.cn/Article/CJFDTOTAL-YSXB801.004.htm
[43]	杨启军, 钟增球, 2004. 大别-苏鲁超高压地体中面理化含榴花岗岩的成因研究. 地球科学———中国地质大学学报, 29 (2): 169 - 176. https://www.cnki.com.cn/Article/CJFDTOTAL-DQKX200402008.htm
[44]	杨启军, 钟增球, 周汉文, 2003. 大别-苏鲁超高压地体折返过程中岩石组合演化的地球化学约束. 地球科学———中国地质大学学报, 28 (3): 241 - 249. https://www.cnki.com.cn/Article/CJFDTOTAL-DQKX200303001.htm
[45]	张宏飞, 高山, 张本仁, 等, 2001. 大别山地壳结构的Pb同位素地球化学示踪. 地球化学, 30(4): 395 - 401. doi: 10.3321/j.issn:0379-1726.2001.04.014
[46]	张利, 钟增球, 张本仁, 等, 2004. 桐柏-大别造山带高压变质单元面理化(含榴)花岗岩地球化学及其对岩石成因的限制. 地球化学, 33 (3): 232 - 242. doi: 10.3321/j.issn:0379-1726.2004.03.002
[47]	张理刚, 刘敬秀, 王可法, 等, 1995. 东亚岩石圈块体地质———上地幔、基底和花岗岩铅同位素地球化学及其动力学. 北京: 科学出版社, 252.
[48]	朱炳泉, 常向阳, 2001. 地球化学省与地球化学边界. 地球科学进展, 16(2): 153 - 162. doi: 10.3321/j.issn:1001-8166.2001.02.003