LATERAL VARIATION OF CRUSTAL COMPOSITION IN CHINA AS REVEALED BY HEAT FLOW STUDY
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摘要: 依据大地热流值、地壳厚度以及大陆壳/幔热流比与地下流体氦同位素比值的相关关系, 计算出中国主要构造单元地壳生热率.同时, 根据Rudnick和Fountain (1995) 的数据得到地壳生热率和SiO2质量分数的线性关系, 进而利用生热率数据得到地壳SiO2质量分数.此方法得到的中国东部地壳生热率和SiO2质量分数与基于地震波速的成分模型相符.中国大陆地壳生热率和SiO2质量分数横向变化明显, 东部地区地壳为中性成分, 相对富集强不相容元素; 而西北部盆地地壳成分偏于中基性.华北、扬子和塔里木地壳成分差异较大, 克拉通内部表现出明显的成分非均匀性, 褶皱带地壳一般较克拉通略富长英质组分.Abstract: The crustal heat generation rate of major tectonic units in China are calculated on the basis of heat flow, crustal thickness as well as the inverse relation between the heat flow ratio of continental crust/mantle and the helium isotopic composition of underground fluid. Meanwhile, the linear relation between heat generation (A) and SiO2 content (w(SiO2)) of the bulk crust is obtained from the data of Rudnick and Fountain (1995). Then, the w(SiO2) of China's crust are derived from the w(SiO2) -A relation. The derived w(SiO2) and A are in agreement with the values obtained from the seismic velocity-based composition models. There exhibits an obvious lateral variation of heat production and w(SiO2) in China's crust. The eastern China crustal composition, intermediate, contains relatively concentrated strong incompatible elements, but the crustal composition of the northwestern China basins is prone to be intermediate to mafic. The crustal compositions in North China, Yangtze craton and Tarim platform are different from each other to a relatively great extent. Obvious lateral variation of composition is also present within cratons. The orogenic crust often contains slightly more felsic components than does craton.
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表 1 不同类型大地构造单元地壳SiO2质量分数和生热率
Table 1. Crustal SiO2 mass fractions and heat productions of geotectonic types
表 2 中国若干主要构造单元地壳生热率和SiO2质量分数
Table 2. Heat productions, SiO2 mass fractions in crust of some major tectonic units in China
表 3 前人发表的中国大陆东部地壳SiO2质量分数和生热率
Table 3. SiO2 mass fractions and heat productions of crust of the eastern China
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[1] Rudnick R L. Making continental crust[J]. Nature, 1995, 378: 571-578. doi: 10.1038/378571a0 [2] Taylor S R, McLennan S M. The geochemical evolution of the continental crust[J]. Rev Geophys, 1995, 33: 241-265. doi: 10.1029/95RG00262 [3] Rudnick R L, Fountain D M. Nature and composition of the continental crust: a lower crustal perspective[J]. Rev Geophys, 1995, 33: 267-309. doi: 10.1029/95RG01302 [4] Wedepohl K H. The composition of the continental crust[J]. Geochim Cosmochim Acta, 1995, 59: 1217-1232. doi: 10.1016/0016-7037(95)00038-2 [5] 鄢明才, 迟清华. 中国东部地壳与岩石的化学组成[M]. 北京: 科学出版社, 1997. 292. [6] Gao S, Luo TC, Zhang B R, et al. Chemical composition of the continental crust as revealed by studies in East China[J]. Geochimica et Cosmochimica Acta, 1998, 62: 1959-1975. doi: 10.1016/S0016-7037(98)00121-5 [7] Morgan P. Crustal radiogenetic heat production and the selective survival of continental crust[J]. J Geophys Res, 1985, 90: 561-570. doi: 10.1029/JB090iS02p0C561 [8] Egorkin A V. Velocity structure, composition and discrimination of crustal provinces in the former Soviet Union[J]. Tectonophysics, 1998, 298: 395-404. doi: 10.1016/S0040-1951(98)00192-9 [9] Jaupart C, Mareschal J C. The thermal structure and thickness of continental roots[J]. Lithos, 1999, 48: 93-114. doi: 10.1016/S0024-4937(99)00023-7 [10] Vauchez A, Tommasi A, Barruol G. Rheological heterogeneity, mechanical anisotropy and deformation of the continental lithosphere[J]. Tectonophysics, 1998, 296: 61-86. doi: 10.1016/S0040-1951(98)00137-1 [11] Christensen N I, Mooney W D. Seismic velocity structure and composition of the continental crust: a global view[J]. J Geophys Res, 1995, 100: 9761-9788. doi: 10.1029/95JB00259 [12] 任继舜. 中国及邻区大地构造图(1∶5000000)[M]. 北京: 地质出版社, 1999. [13] McLennan S M, TaylorS R. Heatflowand the chemical composition of continental crust[J]. J Geol, 1996, 104: 369-377. doi: 10.1086/629834 [14] Rudnick R L, McDonough W F, O'Connell R J. Thermal structure, thickness and composition of continental lithosphere [J]. Chemical Geology, 1998, 145: 395-411. doi: 10.1016/S0009-2541(97)00151-4 [15] 汪洋. 利用地下流体氦同位素比值计算大陆壳幔热流比例[J]. 地球物理学报, 2000, 43(6): 762-770. doi: 10.3321/j.issn:0001-5733.2000.06.005 [16] Wang Y, Wang J Y, Xiong L P. Heat flow pattern in the mainland of China and its geodynamic significance[J]. Acta Geologica Sinica(English Edition), 2000, 74: 375-380. [17] 杜建国, 徐永昌, 孙明良. 中国大陆含油气盆地的氦同位素组成及大地热流密度[J]. 地球物理学报, 1998, 41(4): 494-501. doi: 10.3321/j.issn:0001-5733.1998.04.008 [18] 王先彬, 刘刚, 陈践发, 等. 地球内部流体研究的若干关键问题[J]. 地学前缘, 1996, 3(3): 105-118. doi: 10.3321/j.issn:1005-2321.1996.03.011 [19] 徐永昌. 天然气中的幔源稀有气体[J]. 地学前缘, 1996, 3(3): 63-71. doi: 10.3321/j.issn:1005-2321.1996.03.006 [20] Yuan X C. Atlas of geophysics in China, publication No. 201 of the International Lithosphere Program[M]. Beijing: Geological Publishing House, 1996. 217. [21] Gao S, Zhang B R, Jin Z M, et al. How mafic is the lower continental crust[J]. Earth PlanetSci Lett, 1998, 161: 101-117. doi: 10.1016/S0012-821X(98)00140-X [22] 张春霖, 朱苏浙, 罗健儿, 等. 浙闽粤东部火山岩厚度及其控制因素分析[A]. 见: 中国地球物理学会年刊1998 [C]. 西安: 西安地图出版社, 1998. 126. [23] 邓晋福, 吴宗絮, 杨建军, 等. 格尔木-额济纳旗地学断面走廊域地壳—上地幔岩石学结构与上部过程[J]. 地球物理学报, 1995, 38(增刊Ⅱ): 130-144. [24] Li S, Mooney W D. Crustal structure of China from deep seismic sounding profiles[J]. Tectonophysics, 1998, 288: 105-113. doi: 10.1016/S0040-1951(97)00287-4 [25] 赵俊猛, 刘国栋, 卢造勋. 天山造山带与准噶尔盆地岩石圈结构及其动力学模型[A]. 见: 邓乃恭, 雷伟志, 主编. 大陆构造及陆内变形暨第六届全国地质力学学术讨论会论文集[C]. 北京: 地震出版社, 1999. 85-88. [26] Zandt G, Ammon C J. Continental crust composition constrained by measurements of crustal Poisson's ratio[J]. Nature, 1995, 374: 152-154. doi: 10.1038/374152a0 [27] Qiu Y, Gao S, Mcnaughton N J, et al. > 3.0 Ga continental crust in the Yangtze craton, South China: SHRIMP U-Pb zircon and Nd isotopic evidence[J]. Geology, 2000, 28: 11-14. [28] 凌文黎, 高山, 张本仁, 等. 扬子陆核古元古代晚期构造热事件与扬子克拉通演化[J]. 科学通报, 2000, 45: 2343-2348. doi: 10.3321/j.issn:0023-074X.2000.21.019 [29] 张福勤, 刘建忠, 欧阳自远. 华北克拉通基底绿岩的岩石大地构造学研究[J]. 地球物理学报, 1998, 45(增刊): 99-107. https://www.cnki.com.cn/Article/CJFDTOTAL-DQWX1998S1010.htm [30] Cleotingh S, Burov E B. Thermomechanical structure of European continental lithosphere: constraints from rheological profiles and EETestimates[J]. Geophys J Int, 1996, 124: 695-723. doi: 10.1111/j.1365-246X.1996.tb05633.x [31] 汪洋. 中国大陆岩石圈力学强度的非均匀性及其地质意义[A]. 见: 邓乃恭, 雷伟志, 主编. 大陆构造及陆内变形暨第六届全国地质力学学术讨论会论文集[C]. 北京: 地震出版社, 1999. 39-42. [32] Christensen N I. Poisson's ratio and crustal seismology[J]. J Geophys Res, 1996, 101: 3139-3156. doi: 10.1029/95JB03446