雪峰山构造带古构造应力场

2013-05-02苏金宝张岳桥董树文李建华马收先崔建军

地球学报 2013年6期

关键词：雪峰山印支燕山

苏金宝, 张岳桥, 董树文, 李勇, 李建华, 马收先, 崔建军

1)中国地质科学院地质力学研究所, 国土资源部新构造运动与地质灾害重点实验室, 北京 100081; 2)中国地质科学院, 北京 100037

雪峰山构造带古构造应力场

苏金宝1), 张岳桥1), 董树文2), 李勇1), 李建华1), 马收先1), 崔建军1)

1)中国地质科学院地质力学研究所, 国土资源部新构造运动与地质灾害重点实验室, 北京 100081; 2)中国地质科学院, 北京 100037

华南地区构造复杂, 中生代动力体制经历了从特提斯构造域向滨太平洋构造域的转换。雪峰山位于华南内部, 其隆升机制也存在广泛争议, 对雪峰山及其邻区古应力场研究, 为华南大陆构造演化动力机制提供了依据。古应力反演显示, 中生代以来, 研究区受到NE向、近SN向、NW向、NNE向四期的构造挤压。NE向与近SN向是华南块体印支期顺时针旋转以及古特提斯洋闭合的结果, NW向挤压是古太平洋板块俯冲作用导致, 而NNE向挤压则与印、藏碰撞的远程效应有关。

印支期挤压; 燕山期挤压; 华南地块

中生代是华南构造的重要变革时期, 华南的主要构造格局被认为定型于中生代的印支与燕山构造事件的陆内造山作用(Chen et al., 1991; Wang et al., 2005; Shu et al., 2006)。但印支与燕山构造事件对华南的作用时限、作用强度和范围还存在争议, 使得对华南陆内造山有不同的解释。如Li等(2007)指出华南1300 km宽的陆内造山是开始于二叠世的古太平洋板块平俯冲作用; 早中生代华南大陆由于软流圈上涌而伸展(Gilder et al., 1996; Sun et al., 2005), Zhou等(2006)认为古太平洋俯冲应在早中侏罗世; 还有学者认为古太平洋板块俯冲的时代是中晚侏罗世(董树文等, 2007; 张岳桥等, 2009)。华南大陆的早中生代构造岩浆活动归功于华南与华北板块的碰撞以及印支块体与华南大陆的碰撞(Li et al., 1998; Wang et al., 2007; Shu et al., 2009; Zhou et al., 2006), Wang等(2005)认为雪峰山是这一时期陆内斜向挤压变形的产物, 然而这难以解释这些碰撞造山如何传播到块体内部, 以及造山带走向与碰撞带走向近垂直(Li et al., 2007)。李三忠等(2011)认为雪峰山是NNE向的构造线在印支晚期由于扬子地块顺时针旋转变位为NEE向, 随后又叠加了第二幕NEE向构造线形成。张岳桥等(2009)通过地表形迹学分析提出华南印支期是近南北向挤压, 而燕山期转为NW向或近东西向挤压。古应力场反演能为解决华南相对华北块体旋转前后的应力变化、华南动力方向来源提供依据, 因而本文着重对雪峰山构造带中生代古应力场进行反演, 进而分析华南大陆动力演化模式。

图1 研究区平面地质图Fig. 1 Geological map of the study area

扬子与华夏块体的拼合时间一般认为是在格林威尔期(ca. 1.1～0.9 Ga, Shui, 1987; Chen et al., 1998; Li et al., 2002; Ye et al., 2007)或新元古0.87～0.82 Ga (Zhao et al., 1999; Wang et al., 2004; Zheng et al., 2007)。扬子变质基底主要由云母片岩、片岩、绢云母泥砂岩复理石及硅质岩和成层较好的杂砂岩-板岩组成(Yan et al., 2003; Shu et al., 2006, 2008)。扬子与华夏块体碰撞后发育为新元古—古生代裂谷, 中心为最大可达13 km深海碳酸岩碎屑岩和边部为2～5 km厚的浅海碳酸岩沉积(Wang et al., 2003; Wang et al., 2007)。沉积盖层主要是寒武系黑色页岩、砂岩、灰岩夹白云岩, 奥陶系厚层灰岩夹白云岩粘土粉砂岩, 志留系页岩及砂岩, 泥盆系砂岩与粉砂岩, 石炭系碎屑岩与灰岩, 二叠系灰岩等(Yan et al., 2009)。早三叠系为灰岩夹泥灰岩页岩, 此后以陆相地层为主。研究区经历多期构造事件, 如加里东构造事件使晚泥盆系角度不整合在志留系之上(Charvet et al., 1996; Shu et al., 2006; Sun et al., 2005)。接下来为三叠系的脆韧性变形及华南广泛岩浆事件被认为是印支事件的产物(e. g. Yang et al., 1982; Li et al., 2006; Wang et al., 2001; Wang et al., 2005; Zhou et al., 2006)。燕山期形成后碰撞陆内山间盆地与陆内伸展盆地(Shu et al., 2009)。

研究区恰位于扬子与华夏的拼合带, 是以NE走向为主的构造带(图1), 雪峰山以东为上古生界地层为主的湘中褶皱带, 并发育叠加褶皱。雪峰山出露前寒武系基底, 上覆下古生界地层, 残留的上古生界地层相对较少, 中生代盆地不整合在其上。

1 古应力分析与分期

1.1 古应力方法

一般而言, 地壳在一定演化阶段, 构造应力场是相对统一的, 其主应力方向基本保持不变, 因此可通过多种地质方法反演古构造应力场方向。在脆性变形区, 较为常用的方法是通过观测断面上的擦痕滑动失量来反演古构造应力场(Carey, 1979; Angelier, 1984; Mercier et al., 1987)。用各种滑动构造标志判别断层的运动方向, 通过计算机计算各观测点三轴主应力方向。再结合叠加擦痕、断层相互的切割关系, 确定构造应力场演化序列。古应力反演主要是通过T-TECTO软件, 它是应用Gauss方法(Žalohar et al., 2007)对断裂滑动数据进行古应力与运动分析, 最佳拟合应力方向, 并成功应用于构造地质研究中(如Žalohar et al., 2008, 2010)。

华南地区晚古生代至中三叠世地层(D2-3—T2),通常称为印支构造层, 其底部不整合超覆在下古生界加里东构造层之上, 泥盆系底部为一套河流相砂砾岩沉积, 向上主体为浅海相碳酸盐沉积, 其中有海陆交互相沉积夹层。晚三叠世至早中侏罗世地层(T3—J1-2)构成了早燕山构造层, 主体为陆相沉积。

图2 板溪群s0被s1构造置换, 显示NW—SE向挤压Fig. 2 Structural replacement of s0 by s1 in Banxi Group, showing NW–SE trending compression a-F29点; b-F30点; c-F34点; d- F35点(位置见图3) a-F29; b-F30; c-F34; d-F35 (locations as for Fig. 3)

我们对湘桂褶皱带与雪峰山地区相应的印支与燕山构造层以及后期的白垩系中构造断层与擦痕等进行了测量并做古应力的恢复, 印支构造层灰岩较多, 因而易产生擦痕, 而燕山构造层限于出露地层少而相对擦痕要少一些, 如图版I所示。为了避免层面滑动对应力判别上的失准, 因而在擦痕测量中,擦痕均来自垂直或斜交层面的断层面上。我们假设地层在受到挤压前是水平沉积, 初始挤压会使断层面上的擦痕与地层近于平行, 而当地层褶皱变形,再次受到挤压时擦痕近似与地层斜交。这样在测量擦痕的同时, 我们可人为的将擦痕分为两组, 即平行地层层面s0的与不平行s0的两组擦痕。在测量擦痕的过程中, 对同一构造面叠加的擦痕进行先后分期, 最终可算出挤压应力的先后顺序。

1.2 古应力分期

通过测量反演, 研究区自中生代以来至少经历了NE向、近SN向、NW或近东西向、NNE向挤压等4期构造事件。

在测量XX122点中, 不同构造面上反演出三期的构造挤压(如图版I-c, d, e)。平行s0的擦痕反演挤压应力为NE—SW向挤压, 不平行s0的擦痕反演出NE向与近SN向挤压。我们认为平行s0擦痕代表地层初始NE向挤压时地层平缓产生, 随挤压加大,地层褶皱并使擦痕与s0不平行, 近南SN向挤应该在北东向挤压之后。

XX159点, 在同一构造面上产生了两期叠加的擦痕(图版I-a), 早期向北倾的擦痕被晚期向南倾的擦痕所叠加, 对所测擦痕反演, 早期显示NE向挤压,晚期为NNE向。同时还反演出近南北向的挤压应力。此时还不能判断NNE向挤压与近SN向挤压先后。

华南褶皱带表现为NE走向, NW向挤压是普遍存在的, 雪峰山主要呈北东向构造。雪峰山出露的老地层板溪群, s0被s1置换, s1产状总体指向NW—SE, 如图2所示, 说明NW向构造挤压的强烈。在应力反演中也表现出NW向的挤压如xx164点(图版I-b)。此处擦痕反演出三期挤压, 而平行s0擦痕反演出一期NE向挤压和一期NW向挤压, 推测NE向为最早阶段的挤压, 这次挤压并未使该处地层强烈倾斜。在此之后, 地层受到北西向挤压, 因而产生的擦痕同样与s0近于平行。此处还发育一些逆断层, 断层向西倾(图版I-b), 在断层面上测得擦痕反演显示地层受到NNE方向挤压。这期NNE向挤压应发生在NW向挤压之后。

在XX171点中(图版I-f), 平行s0擦痕反演出一近SN向的挤压, 同时不平行s0擦痕反演出NNE向挤压, 说明近SN向挤压应在NNE向挤压之前。至此推断XX159点(图版I-a)近SN向挤压应发生在NNE向挤压之前, 结合区域构造事件, 近SN向挤压应发生在NW向挤压之前。

结合上述, 我们分析出四期的构造挤压, 先后为NE向、近SN向、NW向、NNE向, 数据如表1。图3显示所有测试点位置以及古应力状况。自中生代以来, 研究区经历两大构造域, 最初的NE向与近SN向挤压很可能是与古特提斯洋闭合有关; 而NW向挤压则是太平洋板块向欧亚大陆俯冲的结果; 最新的NNE向挤压可能是喜山期印藏碰撞远程效应的影响。喜山期的NNE向挤压也可在喜山构造层(J2-K)中反演得以确认, 我们在J2与K地层中测得ym315点与ym340点(如图3)也反演出NNE向挤压,说明白垩之后是存在一期NNE向挤压。

图3 古构造挤压应力场Fig. 3 The principal compressional stress filed

2 讨论

华南大陆四期构造挤压的识别为探讨华南中生代构造体制转换和大地构造过程提供了关键的构造地质学依据。从大地构造发展角度看, 华南地区四

期的构造挤压反映了印支期以来华南所受挤压应力变化。印支期华南块体顺时针旋转与华北块体拼贴,形成以东西向构造为主的特提斯构造域, 挤压应力为NE向后变为近SN向。燕山期, 特提斯构造域向滨太平洋构造域转换形成以NW向挤压为主的NNE向构造。华南印支—早燕山构造层中的叠加褶皱构造(张岳桥等, 2009, 2012)是挤压应力变化的直接结果。喜山期, 中国东部存在一些构造挤压, 盆地中出现了构造反转, 如济阳坳陷等(Su et al., 2009; 苏金宝等, 2011), 这些挤压事件很有可能是与印藏碰撞的远程效应有关。在测得挤压应力时NNE向挤压出现较晚, 在白垩盆地中也反演出这期的挤压应力,其时代显然要晚于印支期挤压, 因此我们把NNE向挤压定义为喜山期的构造事件。

表1 湘中褶皱带与雪峰山地区断层滑动失量及其构造应力场反演结果Table 1 Fault slip vectors measured in central Hunan and Xuefeng Mountain regions and their inverted results of stress fields

续表1

华南地区印支期近东西褶皱构造带的形成与华南大陆南、北边缘地块碰撞作用有关。碰撞使大别山、苏鲁造山带出露的超高压变质带年龄峰值约为240 Ma(Li et al., 1993; Hacker et al., 1998), 这期挤压使华南地块发生挤压增厚, 并导致华南印支期过铝质花岗岩的发育(Wang et al., 2007)。然而雪峰山在印支期构造线为NNE向, 二者同期的构造线近乎垂直(Wang et al., 2005; 李三忠等, 2011)。李三忠等(2011)认为扬子地块北缘与秦岭—大别山带印支期变形方位一致的变形区域只限制在其南侧50 km以内, 其余的扬子地块内部的印支期变形方位和秦岭—大别造山带无关。Li等(2007)提出华南1300 km褶皱带是与二叠纪开始的古太平洋平俯冲有关, 但因在中国东部没有发现印支期俯冲证据而受质疑。古应力结果揭示, 中生代以来华南大陆内部变形印支期是与特提斯闭合产生的NE向与近SN向挤压所致, 这也使雪峰山形成左行走滑逆冲构造(Wang et al., 2005)。华南挤压方向转化为NW向为主是受太平洋板板俯冲影响, 俯冲的时间显然不支持发生在印支期。

3 结论

雪峰山及邻区印支—燕山构造层(D-K)反演出四期构造挤压, 分别为NE向、近SN向、NW向、NNE向。早期NE向后转为近SN向, 这与印支期华南块体顺时针旋转与古特提斯闭合有关。燕山期受太平洋板块俯冲影响, 古应力转为NW向挤压。最后一期为NNE向挤压, 我们认为它是与喜山期印藏碰撞的远程效应引起。

董树文, 张岳桥, 龙长兴, 杨振宇, 季强, 王涛, 胡建民, 陈宣华. 2007. 中国侏罗纪构造变革与燕山运动新诠释[J]. 地质学报, 81: 1449-1461.

李三忠, 王涛, 金宠, 戴黎明, 刘鑫, 周小军, 王岳军, 张国伟. 2011. 雪峰山基底隆升带及其邻区印支期陆内构造特征与成因[J]. 吉林大学学报(地球科学版), 41: 93-105.

水涛. 1987. 中国东南大陆基底构造格局[J]. 中国科学(B辑), (4): 78-86.

苏金宝, 朱文斌, 贾东, 杨彦峰, 王志强. 2011. 伸展断层相关褶皱的几何学分析及其在车镇凹陷中的的应用[J]. 地质学报, 85: 1563-1573.

张岳桥, 董树文, 李建华, 崔建军, 施炜, 苏金宝, 李勇. 2012.华南中生代大地构造研究新进展[J]. 地球学报, 33(3): 257-279.

张岳桥, 徐先兵, 贾东, 舒良树. 2009. 华南早中生代从印支期碰撞构造体系向燕山期俯冲构造体系转换的形变记录[J].地学前缘, 15(6): 1-14.

References:

ANGELIER J. 1984. Tectonic analysis of fault slip data sets[J]. Jour geophy Res, 89: 5835-5848.

CAREY E. 1979. Recherche des directions principales de contraintes associees au jeu d’une population de failles[J]. RevGeol. Dyn. Geogr. Phys, 21: 57-66.

CHARVET J, SHU L S, SHI Y S, GUO L Z, FAURE M. 1996. The building of south China: collision of Yangzi and Cathaysia block, problems and tentative answers[J]. J. Southeast Asian Earth Sci., 13(3-5): 223-235.

CHEN Jiang-feng, FOLAND K A, XING Feng-ming, XU Xiang, ZHOU Tai-xi. 1991. Magmatism along the southeast margin of the Yangtze block: Precambrian collision of t he Yangtze and Cathaysia blocks of China[J]. Geology, 19: 815-818.

CHEN Jiang-feng, JAHN B M. 1998. Crustal evolution of southeastern China: Nd and Sr isotopic evidence[J]. Tectononphysics, 284: 101-133.

DONG Shu-wen, ZHANG Yue-qiao, LONG Chang-xing, YANG Zhen-yu, JI Qiang, WANG Tao, HU Jian-min, CHEN Xuan-hua. 2007. Jurassic tectonic revolution in China and new interpretation of the Yanshan Movement[J]. Acta Geologica Sinica, 81: 1449-1461(in Chinese with English abstract).

GILDER S A, GILL J, COE R S, ZHAO Xi-xi, LIU Zhong-wen, WANG Gen-xian, YUAN Kui-rong, LIU Wen-long, KUANG Guo-dun, WU Hao-ruo. 1996. Isotopic and paleomagnetic constraints on the Mesozoic tectonic evolution of south China[J]. J. Geophys. Res., 101: 16137-16154.

HACKER B R, RATSCHBACHER L, WEBB L, IRELAND T, WALKER D, DONG S W. 1998. U/Pb zircon ages constrain the architecture of the ultrahigh-pressure Qinling-Dabie Orogen, China[J]. Earth and Planetary Science Letters, 161: 215-230.

LI Shu-guang, XIAO Yi-lin, LIU De-liang, CHEN Yi-zhi, GE Ning-jie, ZHANG Zong-qing, SUN Shen-su, CONG B L, ZHANG R Y, HART S R. 1993. Collision of the North China and Yangtze blocks and formation of coesite-bearing eclogites: timing and process[J]. Chemical geology, 109: 89-111.

LI San-zhong, WANG Tao, JING Chong, DAI Li-ming, LIU Xin, ZHOU Xiao-jun, WANG Yue-jun, ZHANG Guo-wei. 2011. Features and causes of Indosinian Intracontinental structures in the Xuefengshan Precambrian basement and its neighboring regions[J]. Journal of Jilin University (Earth Science Edition), 41: 93-105(in Chinese with English abstract).

LI Zheng-xiang, LI Xian-hua. 2007. Formation of t he 1300 km wide intracontinental orogen and postorogenic magmatic province in Mesozoic South China: A flat slab subduction model[J]. Geology, 35: 1792182.

LI Zheng-xiang. 1998. Tectonic history of the major East Asian lithospheric blocks since the mid-Proterozoic[C]//A synthesis: American Geophysical Union Geodynamics Series, 27: 221-243.

LI Zheng-xiang, LI Xian-hua, ZHOU Han-wen, KINNY P D. 2002. Grenvillian continental collision in south China: new SHRIMP U–Pb zircon results and implications for the configuration of Rodinia[J]. Geology, 30: 163-166.

LI Xian-hua, LI Zheng-xiang. LI Wu-xian, WANG Yue-jun. 2006. Initiation of the Indosinian Orogeny in SouthChina: Evidence for a Permian Magmatic Arc on Hainan Island[J]. J. Geol., 114: 341-353.

MERCIER J L, ARMIJO R, TAPPONNIER P. 1987. Change from late Tertiary compression to Quaternary extension in southern Tibet during the India-Asia collision[J]. Tectonics, 6(3): 275-304.

SHU Liang-shu, FAURE M, JIANG Shao-yong, YANG Qun, WANG Yu-jing. 2006. SHRIMP zircon U–Pb age, lithoand biostratigraphic analyses of the Huaiyu Domain in South China— Evidence for a Neoproterozoic orogen, not Late Paleozoic–Early Mesozoic collision[J]. Episodes, 29: 244-252.

SHU Liang-shu, FAURE M, WANG Bo, ZHOU Xin-min, SONG Biao. 2008. Late Paleozoic-early Mesozoic geological features of South China: response to the Indosinian collision event in southeast Asia[J]. C.R. Geosci., 340(2-3): 151-165.

SHU L S, ZHOU X M, DENG P, WANG B, JIANG S Y, YU J H, ZHAO X X. 2009. Mesozoic tectonic evolution of the southeast China Block: new insights from basin analysis[J]. Journal of Asian Earth Sciences, 34(3): 376-391.

SHUI Tao. 1987. Continental basement tectonic framework of Southeast China[J]. Scinece in China(B), 4: 414-422(in Chinese with English abstract).

SU Jin-bao, ZHU Wen-bin, JIA Dong, YANG Yan-feng, WANG Zhi-qiang. 2011. Geometric analysis of extensional fault-related folding and its applications on Chenzhen depression[J]. Acta Geologica Sinica, 85: 1563-1573(in Chinese with English abstract).

SU Jin-bao, ZHU Wen-bin, LU Hua-fu, XU Ming-jie, ZHANG Zhi-yong. 2009. Geometry styles and quantification of inversion structures in the Jiyang depression, Bohai Bay Basion, eastern China[J]. Marine and Petroleum Geology, 26: 25-38.

SUN Tao, ZHOU Xin-min, CHEN Pei-rong, LI Hui-min, ZHOU Hong-ying, WANG Zi-cheng, SHEN Wwei-zhou. 2005. Mesozoic strongly peraluminous granites from eastern Nanling Mountains Range, southern China: Petrogenesis and implications for tectonics[J]. Sci. China D, 48(2): 165-174.

WANG Qiang, LI Jian-wei, JIAN Ping, ZHAO Zhen-hua, XIONG Xiao-lin, BAO Zhi-wei, XU Ji-feng, LI Chao-feng, MA Jin-long. 2005. Alkaline syenites in eastern Cathaysia (South China): Link to Permian–Triassic transtension[J]. Earth Planet. Sci. Lett., 230(3-4): 339-354.

WANG Yue-jun, ZHANG Yan-hua, FAN Wei-ming, PENG Tou-ping. 2005. Structural signatures and40Ar/39Ar geochronology of the Indosinian Xuefengshan tectonic belt, South China Block[J]. Journal of Structural Geology, 27(6): 985-998. WANG Bo, SHU Liang-shu. 2001. Notes on Late Paleozoic radiolarians of northeastern Jiangxi Province[J]. Geol. Rev., 47:337-344.

WANG Jian, LI Zheng-xiang. 2003. History of Neoproterozoic rift basins in South China: implications for Rodinia break-up[J]. Precambrian Res., 122(1-4): 141-158.

WANG Xiao-lei, ZHOU Jin-cheng, GRIFFIN W L, WANG Ru-cheng, QIU Jian-sheng, O’REILLY S Y, XU Xi-sheng, LIU Xiao-ming, ZHANG Gui-lin. 2007. Detrital zircon geochronology of Precambrian basement sequences in the Jiangnan orogen: dating the assembly of the Yangtze and Cathaysia blocks[J]. Precambrian Res., 159(1-2): 117-131.

WANG Xiao-lei, ZHOU Jin-cheng, QIU Jian-sheng, GAO Jian-feng. 2004. Geochemistry of the Meso- to Neoproterozoic basic-acid rocks from Hunan Province, South China: implications for the evolution of the western Jiangnan orogen[J]. Precambrian Res., 135(1-2): 79-103.

WANG Yue-jun, FAN Wei-ming, SUN Min, LIANG Xin-quan, ZHANG Yan-hua, PENG Tou-ping. 2007. Geochronological, geochemical and geothermal constraints on petrogenesis of the Indosinian peraluminous granites in the South China Block: A case study in the Hunan province[J]. Lithos, 96(1-4): 475-502.

YAN Dan-ping, ZHANG Bing, ZHOU Mei-fu, WEI Guo-qing, SONG Hong-lin, LIU Shao-feng. 2009. Constraints on the depth, geometry and kinematics of blind detachment faults provided by fault-propagation folds: An example from the Mesozoic fold belt of South China[J]. Journal of structural geology, 31(2): 150-162.

YAN Dan-ping, ZHOU Mei-fu, SONG Hong-lin, WANG Xin-wen, MALPAS J. 2003. Origin and tectonic significance of a Mesozoic multi-layer over-thrust system within the Yangtze Block (South China)[J]. Tectonophysics, 361(3-4): 293-254.

YANG Zun-yi, LI Zhi-shun, QU Li-fan, LU Zhong-ming, ZHOU Hui-qin, ZHOU Tong-shun, LIU Gui-fang, LIU Ben-pei, WU Rui-tang. 1982. The Triassic of China[J]. Acta Geol. Sin., 56: 1-20.

YE Mei-fang, LI Xian-hua, LI Wu-xian, LIU Ying, LI Zheng-xiang. 2007. SHRIMP zircon U-Pb geochronological and whole-rock geochemical evidence for an early Neoproterozoic Sibaoan magmatic arc along the southeastern margin of the Yangtze Block[J]. Gond. Res., 12(1-2): 144-156.

ZHANG Yue-qiao, XU Xian-bing, JIA Dong, SHU Liang-shu. 2009. Deformation record of the change from Indosinian collision-related tectonic system to Yanshanian subduction-related tectonic system in South China during the Early Mesozoic[J]. Earth Science Frontiers, 16: 234-247(in Chinese with English abstract).

ZHANG Yue-qiao, DONG Shu-wen, LI Jian-hua, CUI Jian-jun, SHI Wei, SU Jin-bao, LI Yong, 2012. The new progress in the study of Mesozoic tectonics of South China[J]. Acta Geoscientica Sinica, 33(3): 257-279(in Chinese with English abstract).

ZHAO Guo-chun, CAWOOD P A. 1999. Tectonothermal evolution of the Mayuan assemblage in the Cathaysia Block: implications for Neoproterozoic collision-related assembly of the South China craton[J]. Am. J. Sci., 299(4): 309-339.

ZHENG Yong-fei, ZHANG Shao-bing, ZHAO Zi-fu, WU Yuan-bao, LI Xian-hua, LI Zheng-xiang,WU Fu-yuan. 2007. Contrasting zircon Hf and O isotopes in the two episodes of Neoproterozoic granitoids in South China: implications for growth and reworking of continental crust[J]. Lithos, 96(1-2): 127-150.

ZHOU Xin-min, SUN Tao, SHEN Wei-zhou, SHU Liang-shu, NIU Yao-ling. 2006. Petrogenesis of Mesozoic granitoids and volcanic rocks in South China: A response to tectonic evolution[J]. Episodes, 29(1): 26-33.

ŽALOHAR J, VRABEC M. 2010. Kinematics and dynamics of fault reactivation: The Cosserat approach[J]. Journal of Structural Geology., 32(1): 15-27.

ŽALOHAR J, VRABEC M. 2008. Combined (paleo)stress and kinematic analysis of fault-slip data: the Multiple-slip method[J]. Journal of Structural Geology, 30(12): 1603-1613.

ŽALOHAR J, VRABEC M. 2007. Paleostress analysis of heterogeneous fault-slip data: the Gauss method[J]. Journal of Structural Geology, 29(11): 1798-1810.

图版说明

图版I Plate I

a-XX159点反演出三期构造应力, 擦痕显示早晚两期擦痕叠加;

b-XX164点反演出三期构造挤压, 逆断层对应于晚期NNE向挤压;

c-XX122点平行于s0的擦痕反演出的挤压;

d-XX122点不平行s0的擦痕反演出的NE向挤压;

e-XX122点不平行s0的擦痕反演出的近SN向挤压;

f-XX171点构造变形及反演的三期挤压应力(位置见图3)

a-3 stages of stress at XX159 and superimposition of two stages of vectors;

b-3 stages of compressive stress at XX164 and thrust showing NNE-trending compression;

c-stress inverted from vectors parallel to s0 at XX122;

d-NE-trending stress inverted from vectors unparallel to s0 at XX122;

e-nearly NS-trending stress inverted from vectors unparallel to s0 at XX122;

f-structural deformation and 3 stages of compressional stress at XX171

Paleo-structural Stress Field in Xuefengshan Tectonic Belt, South China

SU Jin-bao1), ZHANG Yue-qiao1), DONG Shu-wen2), LI Yong1), LI Jian-hua1), MA Shou-xian1), CUI Jian-jun1)
1) Key Laboratory of Neotectonic Movement and Geohazard, Ministry of Land and Resources, Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081; 2) Chinese Academy of Geological Sciences, Beijing 100037

The structure of South China is complex, and its tectonic regimes underwent a tremendous change from the Tethys tectonic domain to the Pacific tectonic domain during the Mesozoic period. The Xuefengshan tectonic belt (XTB) is located in the interior of South China and its uplift mechanism is debated hotly. The study of stress fields on XTB and its adjacent areas provides a key basis for the dynamic mechanism of tectonic evolution of South China. The inverted stress shows that the study area has experienced four stages of compressive stress since Mesozoic, i.e., NE-trending, nearly NS-trending, NW-trending and NNE-trending compressive stresses. The NE-trending and nearly NS-trending stresses resulted from clockwise rotation of South China and closing of Tethys ocean. The NW-trendiang compression was induced by subduction of paleo-Pacific Ocean towards Eurasia continent, whereas the NNE-trending compression might have been related to the far-distance effect of collision between the India and the Tibet plates.

Indosinian compression; Yanshannian compression; South China block