湖南大义山、塔山岩体锆石U-Pb年龄及其构造意义

李　勇, 张岳桥, 苏金宝, 李建华, 董树文

1)北京大学, 北京 100871;　2)中国地质科学院地质力学研究所, 北京 100081; 3)河海大学, 江苏南京 210098;　4)中国地质科学院, 北京 100037

湖南大义山、塔山岩体锆石U-Pb年龄及其构造意义

李勇1,2), 张岳桥2), 苏金宝3), 李建华2), 董树文4)*

1)北京大学, 北京 100871;2)中国地质科学院地质力学研究所, 北京 100081; 3)河海大学, 江苏南京 210098;4)中国地质科学院, 北京 100037

华南中部地区大义山、塔山等早中生代花岗岩的展布和侵入特征与这一时期褶皱构造之间存在着非常密切的关系, 对这些岩体进行精确年代学研究, 可以为构造变形时代提供年代学约束。大义山岩体南部地区锆石U-Pb LA-ICP-MS年龄为东缘(171.8±1.9) Ma、西缘(169.9±1.8) Ma、中部(164.2±2.6) Ma, 塔山岩体东段为(247±5.9) Ma。大义山岩体在164.2—171.8 Ma之间经历两个期次的侵入, 形成了一个复式岩体, 岩体形成后至125 Ma经历了快速隆升, 之后以接近1°C/Ma的冷却速率抬升到地表。大义山和塔山岩体记录了华南早中生代印支和燕山两期重要的岩浆活动。阳明山、塔山岩体等E—W向展布岩体受印支期构造带控制; 大义山、骑田岭等岩体年龄限定了燕山期构造地层的变形下限时代, 华南地区NNE向褶皱构造形成时代应早于(171.8±1.9) Ma。

华南地区; 大义山岩体; 塔山岩体; 锆石U-Pb年龄

华南板块分布着巨量的花岗岩体, 这些岩体为研究同期构造事件提供很好的窗口(Zhou et al.,2000; Zhou et al., 2006; Zhou et al., 2007)。中生代的“印支运动”和“燕山运动”是对华南大地构造具有重要影响的两次构造事件, 与这两次构造事件对应的同期岩浆活动存在着一个明显的平静期, 将两期构造事件分开(Zhou et al., 2006)。由于大量不同期的侵入岩和火山岩的发育破坏了原始沉积地层,尤其是东南沿海地区, 所以难以确定华南地区中生代“印支运动”与“燕山运动”两次构造事件转换的精确时代。从东南沿海向华南内陆岩浆作用逐渐减弱, 在华南中部地区岩体的分布与构造地层之间存在非常清楚的时代关系, 通过对这些岩体的分布特征和精确年代学的研究, 可以对这两次构造事件的转换时代提供约束。

大义山岩体位于湖南南部, 属于南岭中段重要的锡铅锌多金属含矿岩体。李四光研究大义山式构造时, 将该岩体称为“大义山式”花岗岩(李四光, 1973)。大义山岩体一直被认为是一个多时代、多期次侵入的复式岩体, 常以关口—野鹿滩一线为界,分成了南体和北体两部分(刘耀荣等, 2006)。长期以来由于缺少精确的年代学研究, 对于大义山岩体形成时代存在不同认识, 伍光英等(2000, 2005)研究大义山岩体地质特征和岩体侵位机制时把南体归于中三叠世, 整体岩体同位素年龄为210～278 Ma, 156～185 Ma和128～148 Ma, 侵人时代从印支期持续到燕山晚期。刘耀荣等(2006)对南体北侧的中细粒斑状黑云母二长花岗岩中黑云母作Ar-Ar法定年测试, 其年龄为156.2 Ma, 认为岩体形成时间应为中—晚侏罗世, 相当于“燕山”早期。塔山岩体和阳明山岩体呈东西向展布, 阳明山岩体年龄为218 Ma, 属于三叠纪“印支”岩体(范蔚茗等, 2004; Li X H et al., 2007; 罗志高等, 2010), 塔山岩体西段年代为(224±2) Ma也属于三叠纪“印支期”(Chu et al., 2012), 但塔山岩体东段年代一直未见报道。对大义山和塔山岩体进行精确的年代学研究, 能够更好地理解华南早中生代大地构造过程, 尤其是对于华南地区中生代“印支运动”与“燕山运动”两次构造事件的转换时代能够更好地提供约束。

1　区域大地构造背景及样品采集

整个华南经历了多期次区域规模的大陆动力学过程, 大多具有板块内部变形的特点, 只有在新元古代和晚中生代具有活动陆缘背景(Charvet, 2013; 舒良树, 2012)。从晚古生代开始到中三叠纪(D2-3-T2)处在一个稳定浅海相的沉积环境, 华南板块在这一时期经历了伸展拉张作用成为一个洋盆,古地壳基底减薄, 通常将这一时期的海相地层称为印支构造层, 其底部不整合超覆在前泥盆地层之上,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, 仅在华南东南部沿海地区分布海相地层, 整个华南地区的沉积地层已发生强烈挤压变形, 形成构造样式复杂、东西宽大于1300 km的褶皱构造带(Li Z X et al., 2007; 徐先兵等, 2009; 张岳桥等, 2009; Wang et al., 2013), 两套构造层之间成角度不整合接触。在两套构造层中大量分布着叠加构造, 如广西柳州山字形叠加构造、南岭中段叠加构造、鄂西南湘北地区叠加褶皱构造、赣中地区叠加褶皱构造、尤其是湘中南地区叠加构造最为典型(图1), 其特点是早期褶皱构造轴呈近东西或北西西—南东东向展布, 晚期呈北东—北北东向展布, 局部地区为南北向(张岳桥等, 2009)。湘中南地区横跨叠加褶皱构造是对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, 而这两个构造体系转换的时间可以用构造地层的侵入岩体年龄来限定(徐先兵等, 2009; 张岳桥等, 2009, 2012)。

本文研究区域大义山、塔山岩体位于华南中部湘南叠加构造发育地区。大义山岩体长约39 km, 宽约10 km, 总面积250 km2左右, 侵入的最老地层为元古界板溪群至中寒武地层, 只在西缘中部地区侵入, 岩体主体侵入到泥盆至石炭纪的碳酸盐岩中,地层发育强烈近南北向褶皱构造, 鉴于大义山岩体形成时代分歧主要集中在南部, 本文在岩体南部从西缘, 中部和东缘各采集了一块样品, 进行LA-ICP-MS锆石U-Pb法年代学分析。塔山岩体东西长25 km, 南北宽12 km, 总面积约为200 km2,岩体处在东西向大背斜核部, 主体侵入到寒武、奥陶和志留纪地层中, 只在东缘侵入到泥盆纪灰岩中,本研究在塔山岩体东段中心部位采集了一块样品进行LA-ICP-MS锆石U-Pb法年代学研究。具体采样地点和分析结果见图2。

2　LA-ICP-MS锆石U-Pb法测试方法与测试结果

2.1测试方法

定年样品均采集自新鲜花岗岩露头, 首先经粉碎、淘洗、磁选和重液分选后分离出锆石, 在双目镜下仔细挑出不同晶形、不同颜色的锆石单矿物,在玻璃板上对锆石进行精选, 然后用环氧树脂将其固定凝结, 再打磨至锆石颗粒中心, 最后进行抛光处理。在开始锆石U-Pb分析前, 用装有阴极荧光探头的扫描电镜对锆石样品进行阴极发光(CL)照相,以确定锆石颗粒的内部结构, 选取适合定年分析的锆石颗粒, 样品年代学测试是在中国地质科学院国家地质实验测试中心完成, 代表性锆石颗粒的CL图像见图3。详细的分析流程、分析精度和准确性见宋彪等(宋彪等, 2002)。分析结果根据Andersen (2002)方法进行普通Pb校正。每个锆石微区原位测试点的同位素比值和U-Pb年龄由专用的GLITTER软件计算, 采用Isoplot程序计算和绘制加权平均年龄及谐和图。

图1　华南中部构造简图Fig. 1　Simplified structural map of central South China

图2　大义山、塔山岩体构造简图和采样位置(绿色五角星标识)Fig. 2　Simplified structural map of Dayishan pluton and Tashan pluton, showing sampling sites (green stars)

图3　大义山、塔山岩体部分锆石的阴极发光图像、原位测试点(圆圈)和206Pb/238U视年龄Fig. 3　CL images, locations of the points for LA-ICP-MS measurements (white circles) and206Pb/238U apparent ages of representative detected zircons from Dayishan pluton and Tashan pluton

2.2测试结果

从样品的显微镜下观察和CL图像可见, 所分析的锆石均为透明—浅褐色, 棱角清楚, 表面光滑,普遍发育平行的晶体生长环带, 少数锆石出现破损和局部熔蚀现象。晶体形态大部分为长板状, 长宽比主要集中在2:1～4:1之间, 颗粒较大, 其长宽比可达5:1。粒径介于100～300 μm之间。图3为部分测定锆石的阴极发光图像, 从图3中可看到锆石颗粒均可见清晰的内部结构, 都具有震荡环带生长边岩浆结晶成因的特征, 所测试的4个样品几乎所有数据点都投影在206Pb/238U-207Pb/235U谐和曲线上或谐和曲线附近, 表明这些锆石颗粒在形成后的U-Pb同位素体系是基本封闭的, 没有U或Pb同位素的明显丢失或加入, 测试获得的年龄可以代表岩体的结晶年龄。表1列出了大义山和塔山岩体岩石锆石U-Pb同位素定年结果, 图4为年龄谐和图, 测试点的误差椭圆大小为68.3％置信度。本文所测定的花岗岩都是早中生代形成, 由于235U和238U的半衰期及丰度不同, 对于较年轻的锆石(<1 Ga), 采用206Pb/238U年龄更加准确(Griffin et al., 2004; 邱检生等, 2011), 因此本文采用了206Pb/238U年龄进行加权平均值的计算。

样品Xn12-1采自大义山岩体南部东缘, 锆石颗粒阴极发光图像和测试结果如图3、图4和表1所示。共选取17粒晶体生长环带比较发育的淡黄色锆石进行了分析, 所有测试点参与计算, 绝大部分数据点都位于谐和线上, 它们的206Pb/238U加权平均年龄为(171.8±1.9) Ma, MSWD=0.25, 该年龄代表了岩体的结晶年龄。

样品Xn306-1采自塔山岩体东段中心部位, 锆石颗粒阴极发光图像和测试结果如图3、图4和表1所示。共选取12粒晶体生长环带比较发育的淡黄色锆石进行了分析, 所有测试点参与计算, 它们的206Pb/238U加权平均年龄为(247.2±5.9) Ma, MSWD=3.5, 该年龄可以代表岩体的结晶年龄。

样品Xn312-1采自大义山岩体南部中心, 锆石颗粒阴极发光图像和测试结果如图3、图4和表1所示。共选取19粒晶体生长环带比较发育的淡黄色锆石进行了分析, 所有测试点参与计算, 绝大部分数据点都位于谐和线上, 它们的206Pb/238U加权平均年龄为(164.2±2.6) Ma, MSWD=1.8, 该年龄代表了岩体的结晶年龄。

样品Xn316-1采自大义山岩体南部西缘, 锆石颗粒阴极发光图像和测试结果如图3、图4和表1所示。共选取17粒晶体生长环带比较发育的淡黄色锆石进行了分析, 所有测试点参与计算, 绝大部分数据点都位于谐和线上, 它们的206Pb/238U加权平均年龄为(169.9±1.8) Ma, MSWD=1.10, 该年龄代表了岩体的结晶年龄。

3　构造意义

3.1大义山岩体的隆升历史

本文给出的大义山岩体锆石U-Pb年龄为164.2～171.8 Ma, 参考柏道远等(2006)钾长石K-Ar年龄为(121.6±1.2) Ma、黑云母K-Ar年龄(146.4±1.4) Ma, 磷灰石裂变痕迹(FT)年龄为(23.1±3.2) Ma、(32.3±7.7) Ma和(刘耀荣等, 2006)钾长石40Ar/39Ar年龄为(156.2±1.6) Ma。结合各矿物封闭温度所构成的演化曲线(图5)来看, 大义山岩体在164.2～171.8 Ma之间经历两个期次的侵入, 形成了一个复式岩体, 岩体形成后至125 Ma经历了快速隆升, 冷却速率接近14°C/Ma, 假定中国南方地壳平均地温梯度与古地温梯度一致为24.1℃/km(袁玉松等, 2006), 那么岩体隆升速率约为0.58 km/Ma,之后以接近1℃/Ma的冷却速率抬升到地表, 隆升速率约为0.041 km/Ma。来自古太平洋向西俯冲可能导致华南陆内变形和快速隆升(Zhou et al., 2000; Zhou et al., 2006)。

3.2“印支”与“燕山”构造事件的转换时代约束

图4　大义山和塔山花岗岩ICP-MS锆石U-Pb谐和图(左)和平均年龄(右)Fig. 4　Zircon207Pb/235U–206Pb/238U concordia diagrams of granitoids from Dayishan and Tashan granites

表1　华南中部地区主要的岩浆岩锆石U-Pb年龄Table 1　Zircon U-Pb dating results for the early-middle Mesozoic magmatic rocks in central South China

续表1　

图5　大义山岩体岩浆作用和剥露过程的温度-时间图解Fig. 5　Temperature versus time diagram, showing the evolution history of magmatism and exhumation of Dayishan pluton锆石铀铅年龄来自本研究, Ar-Ar, K-Ar和磷灰石裂变径迹年龄参考自(柏道远等, 2006; 刘耀荣等, 2006)。矿物封闭温度据(陈宣华等, 2010)及引用的相关文献。a、b、c、d分别为冷却速率0.1℃/Ma、1℃/Ma、10℃/Ma和100℃/Ma线。粗虚线为推测冷却曲线。矿物代号: Zr-锆石; Bi-黑云母; Ksp-钾长石; Ap-磷灰石U-Pb age data from this study. Ar-Ar and AFT data from BO et al., 2006 and LIU et al., 2006. The mineral closure temperatures from CHEN et al. (2010) and references cited. The a, b, c, d stand for cooling lines with rates of 0.1 °C/Ma, 1℃/Ma, 10℃/Ma and 100℃/Ma respectively. The thick dashed line represents inferred cooling curve. Zr-zircon, Bi-biotite, Ksp-K-feldspar, Ap-apatite

“印支运动”和“燕山运动”是中生代以来对华南现今大地构造格局具有决定性的两期构造事件,是对古特提斯构造域和古太平洋构造域作用的响应(赵越等, 2004; Dong et al., 2008), 印支期华南大陆变形较弱, 地层中发育两翼平缓的近E—W向的褶皱,强烈的NE向构造主要在早燕山期形成, 盖层和基底变形异常强烈并叠加改造了早期近E—W向构造(郭福祥, 1999; 王清晨, 2009; 张岳桥等, 2009)。华南在400—245 Ma即从晚古生代开始到中三叠纪(D2-3-T2)处在一个稳定浅海相的沉积环境, 华南板块在这一时期经历了伸展拉张作用成为一个洋盆,古地壳基底减薄, 通常将这一时期的海相地层称为印支构造层, 其底部不整合超覆在前泥盆地层之上,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, 仅在华南东南部沿海地区分布海相地层, 整个华南地区的沉积地层已发生强烈挤压变形, 形成构造样式复杂、东西宽大于1300 km的褶皱构造带, 两套构造层之间呈角度不整合接触(Li Z X et al., 2007; 徐先兵等, 2009; Wang et al., 2013)。

要确定华南早中生代构造地层的变形时代, 关键是要分析构造地层与岩浆活动之间的时代关系(张岳桥等, 2009)。华南中部湘南地区是最为典型的叠加褶皱地区, 分布着印支期和燕山期岩体, 印支岩体主要有白马山岩体、关帝庙、阳明山、塔山等,燕山期岩体主要有大义山、骑田岭等(岩体年龄如表1所示)。这一地区大多数印支期岩体呈E—W向展布, 处在E—W向褶皱核部, 受印支期E—W向构造带控制; 燕山期岩体侵入变形地层之中并不受某一个方向的褶皱构造控制(图1)。阳明山和塔山岩体与大义山岩体之间这种分布特征更为清楚(图2),阳明山和塔山岩体侵入在E—W向大型褶皱背斜核部, 背斜两翼之间最宽处达到60 km, 大义山岩体侵入变形地层之中非常截然, 变形地层没有因岩体侵入发生同步隆升变形, 这说明阳明山和塔山岩体与大义山岩体形成处在不同的大地构造环境之中。晚二叠—早中三叠纪是现代东亚板块成形的一个重要聚合时期, 华北与华南板块、华南与印支板块发生了俯冲碰撞(Cai et al., 2009; Carter et al., 2001; Carter et al., 2008; Chen et al., 2011; Li et al., 2010; Metcalfe, 2011, 2013; Morley et al., 2012; Wang et al., 2013; Wu et al., 2013; Zhou et al., 2006), 印支板块与华南板块碰撞与大别—苏鲁超高压变质带形成时限上在同一时期, 同时华南陆内也发生了变形并伴有大量岩浆热事件(Carter et al., 2001; Dong et al., 2008; Metcalfe, 2013), 印支运动时期又是华南板块重要的一个转折时期, 沉积相发生了明显变化, 由海相环境进入到陆相环境, 大陆地壳增厚形成广泛的褶皱构造, 局部小的凹陷地区沉积T3-J1陆相地层,形成了造山型盆地, 盆地物源主要是来自秦岭—大别造山带剥蚀的碎屑岩(Shu et al., 2009; 张岳桥等, 2009; 赵越等, 2004), 来自西南方向的印支板块和北东向华北板块的共同挤压作用导致华南内陆发生变形, 形成了近E—W或NWW—SEE走向的宽缓褶皱(Cai et al., 2009; Sun et al., 2011; Wang et al., 2005; Zhao et al., 2013; Zhu et al., 2009), 阳明山、塔山岩体等E—W向展布的岩体正是在这样的环境中形成的;来自古太平洋板块俯冲作用导致华南板块出现了宽约1300 km褶皱带, 并且以江绍断裂为界, 华南东部成为一个大的岩浆省, 大量逆冲断层在俯冲作用下也相继形成, 下地壳基底增厚上地壳地层发生了强烈变形, 之后华南大陆在晚中生代出现大范围的地壳伸展减薄的环境(Li Z X et al., 2007; Li X H et al.,2007; Li et al., 2013)。大义山、骑田岭等岩体侵入这套变形地层之中限定了变形下限时代, 华南地区NNE向褶皱构造形成时代早于(171.8±1.9) Ma。

4　结论

(1)大义山岩体南部地区锆石U-Pb LA-ICP-MS年龄为东缘(171.8±1.9) Ma、西缘(169.9±1.8) Ma、中部(164.2±2.6) Ma, 塔山岩体东段(247±5.9) Ma。大义山岩体在164.2—171.8 Ma之间经历两个期次的侵入, 形成了一个复式岩体, 岩体形成后至125 Ma经历了快速隆升, 之后以接近1℃/Ma的冷却速率抬升到地表。

(2)大义山和塔山岩体记录了华南早中生代印支和燕山两期重要的岩浆活动。阳明山、塔山岩体等E—W向展布岩体受印支期构造带控制; 大义山、骑田岭等岩体年龄限定了燕山期构造地层的变形下限时代, 华南地区NNE向褶皱构造形成时代应早于(171.8±1.9) Ma。

柏道远, 黄建中, 孟德保, 马铁球, 王先辉, 张晓阳, 陈必河. 2006. 湘东南地区中、新生代山体隆升过程的热年代学研究[J]. 地球学报, 27(6): 525-536.

毕献武, 李鸿莉, 双燕, 胡晓燕, 胡瑞忠, 彭建堂. 2008. 骑田岭A型花岗岩流体包裹体地球化学特征[J]. 高校地质学报, 14(4): 539-548.

陈卫锋, 陈培荣, 黄宏业, 丁兴, 孙涛. 2007. 湖南白马山岩体花岗岩及其包体的年代学和地球化学研究[J]. 中国科学: D辑, 37(7): 873-893.

陈卫锋, 陈培荣, 周新民, 黄宏业, 丁兴, 孙涛. 2006. 湖南阳明山岩体的La—ICP—MS锆石U—Pb定年及成因研究[J]. 地质学报, 80(7): 1065-1077.

陈宣华, 党玉琪, 尹安, 汪立群, 蒋武明, 蒋荣宝, 周苏平, 刘明德, 叶宝莹, 张敏, 马立协, 李丽. 2010. 柴达木盆地及其周缘山系盆山耦合与构造演化[M]. 北京: 地质出版社: 1-365.

丁兴, 陈培荣, 陈卫锋, 黄宏业, 周新民. 2005. 湖南沩山花岗岩中锆石LA-ICPMSU-Pb定年:成岩启示和意义[J]. 中国科学: D辑, 35(7): 606-616.

范蔚茗, 王岳军, 郭锋, 彭头平. 2004. 湘赣地区中生代镁铁质岩浆作用与岩石圈伸展[J]. 地学前缘, 10(3): 159-169.

付建明, 马昌前, 谢才富, 张业明, 彭松柏. 2004. 湖南骑田岭岩体东缘菜岭岩体的锆石SHRIMP定年及其意义[J]. 中国地质, 31(1): 96-100.

郭福祥. 1999. 华南地台盖层褶皱及其形成时期研究[J]. 地质与勘探, 35(4): 5-7.

李华芹, 路远发, 王登红, 陈毓川, 杨红梅, 郭敬, 谢才富, 梅玉萍, 马丽艳. 2006. 湖南骑田岭芙蓉矿田成岩成矿时代的厘定及其地质意义[J]. 地质论评, 52(1): 113-121.

李建华, 张岳桥, 徐先兵, 李海龙, 董树文, 李廷栋. 2014. 湖南白马山龙潭超单元、瓦屋塘花岗岩锆石SHRIMPU-Pb年龄及其地质意义[J]. 吉林大学学报(地球科学版), 48(01): 158-175.

李金冬, 柏道远, 伍光英, 车勤建, 刘耀荣, 马铁球. 2005. 湘南郴州地区骑田岭花岗岩锆石SHRIMP定年及其地质意义[J].地质通报, 24(5): 411-414.

李四光. 1973. 地质力学概论[M]. 北京: 科学出版杜.

刘耀荣, 邝军, 马铁球, 柏道远. 2006. 湖南大义山花岗岩南体黑云母40Ar-39Ar定年及地质意义[J]. 资源调查与环境, 26(4): 244-249.

罗志高, 王岳军, 张菲菲, 张爱梅, 张玉芝. 2010. 金滩和白马山印支期花岗岩体LA-ICPMS锆石U-Pb定年及其成岩启示[J]. 大地构造与成矿学, 34(2): 282-290.

马铁球, 柏道远, 邝军, 王先辉. 2005. 湘东南茶陵地区锡田岩体锆石SHRIMP定年及其地质意义[J]. 地质通报, 24(5): 415-419.

邱检生, 刘亮, 李真. 2010. 浙江黄岩望海岗石英正长岩的锆石U-Pb年代学与Sr-Nd-Hf同位素地球化学及其对岩石成因的制约[J]. 岩石学报, 27(6): 1557-1572.

舒良树. 2012. 华南构造演化的基本特征[J]. 地质通报, 31(7): 1035-1053.

宋彪, 张玉海, 万渝生, 简平. 2002. 锆石SHRIMP样品靶制作、年龄测定及有关现象讨论[J]. 地质论评, 48(Supp.): 26-30.

王清晨. 2009. 浅议华南陆块群的沉积大地构造学问题[J]. 沉积学报, 27(5): 811-817.

王岳军, 范蔚茗, 梁新权, 彭头平, 石玉若. 2005. 湖南印支期花岗岩SHRIMP锆石U-Pb年龄及其成因启示[J]. 科学通报, 50(12): 1259-1266.

伍光英, 潘仲芳, 李金冬, 肖庆辉, 车勤建. 2005. 湘南大义山花岗岩地质地球化学特征及其与成矿的关系[J]. 中国地质, 32(3): 434-442.

伍光英, 彭和求, 贾宝华. 2000. 湘南大义山岩体地质特征及其侵位机制分析[J]. 华南地质与矿产, (3): 1-7.

徐先兵, 张岳桥, 贾东, 舒良树, 王瑞瑞. 2009. 华南早中生代大地构造过程[J]. 中国地质, 36(3): 573-593.

袁玉松, 马永生, 胡圣标, 郭彤楼, 付孝悦. 2006. 中国南方现今地热特征[J]. 地球物理学报, 49(4): 1118-1126.

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, 16(1): 234-247.

赵葵东, 蒋少涌, 姜耀辉, 刘敦一. 2006. 湘南骑田岭岩体芙蓉超单元的锆石SHRIMPU-Pb年龄及其地质意义[J]. 岩石学报, 22(10): 2611-2616.

赵越, 徐刚, 张拴宏, 杨振宇, 张岳桥, 胡健民. 2004. 燕山运动与东亚构造体制的转变[J]. 地学前缘, 11(3): 319-328.

朱金初, 王汝成, 张佩华, 谢才富, 张文兰, 赵葵东, 谢磊, 杨策, 车旭东, 于阿朋. 2009. 南岭中段骑田岭花岗岩基的锆石U-Pb年代学格架[J]. 中国科学: D辑, 39(8): 1112-1127.

References:

ANDERSEN T. 2002. Correction of common lead in U–Pb analyses that do not report204Pb[J]. Chemical Geology, 192(1): 59-79.

BAI Dao-yuan, HUANG Jian-zhong, MENG De-bao, MA Tie-qiu, WANG Xian-hui, ZHANG Xiao-yang, CHEN Bi-he. 2006. Meso-Cenozoic Thermochronological Analysis of the Uplift Process of Mountains in Southeast Hunan[J]. Acta Geoscientica Sinica, 27(6): 525-536(in Chinese with English abstract).

BI Xian-wu, LI Hong-li, SHUANG Yan, HU Xiao-yan, HU Rui-zhong, PENG Jian-tang. 2008. Geochenmical Characteristies of Fluid Inclusions from Qitioanling A-Tye Granite, Hunan Province, China[J]. Geological Journal of China Universites, 14(4): 539-548(in Chinese with English abstract).

CAI Jian-xin, ZHANG Kai-jun. 2009. A new model for the Indo-china and South China collision during the Late Permian to the Middle Triassic[J]. Tectonophysics, 467(1): 35-43.

CARTER A, CLIFT P D. 2008. Was the Indosinian orogeny a Triassic mountain building or a thermotectonic reactivation event?[J]. Comptes Rendus Geoscience, 340(2): 83-93.

CARTER A, ROQUES D, BRISTOW C, KINNY P. 2001. Understanding Mesozoic accretion in Southeast Asia: significance of Triassic thermotectonism (Indosinian orogeny) in Vietnam[J]. Geology, 29(3): 211-214.

CHARVET J. 2013. The Neoproterozoic–Early Paleozoic tectonic evolution of the South China Block: An overview[J]. Journal of Asian Earth Sciences, 74(0): 198-209.

CHEN Cheng-hong, HSIHE Pei-shan, LEE Chi-yu, ZHOU Han-wen. 2011. Two episodes of the Indosinian thermal event on the South China Block: Constraints from LA-ICPMS U–Pb zircon and electron microprobe monazite ages of the Darongshan S-type granitic suite[J]. Gondwana Research, 19(4): 1008-1023.

CHEN Wei-feng, CHEN Pei-rong, ZHOU Xin-min, HUANG Hong-ye, DING Xing, SUN Tao. 2006. Single-zircon La-ICP-MS U-Pb Dating of the Yangmingshan Granitic Pluton in Hunan, South China and Its Petrogenetic Study[J]. Acta Geologica Sinica, 80(7): 1065-1077(in Chinese with English abstract).

CHEN Wei-feng, CHEN Pei-rong, HUANG Hong-ye, DING Xing, SUN Tao. 2007. Chronological and geochemical studies of granite and enclave in Baimashan pluton, Hunan, South China[J]. Science in China Series D: Earth Sciences, 50(11): 1606-1627.

CHEN Xuan-hua, DANG Yu-qi, YING An, WANG Li-quen, JIANG Wu-ming, JIANG Rong-bao, ZHOU Su-ping, LIU Ming-de, YE Bao-ying, ZHANG Min, MA Li-xie, LI Li. 2010. Qaidam Basin tectonic evolution[M]. Beijing: Geological Publishing House: 1-365(in Chinese).

CHU Yang, LIN Wei, FAURE M, WANG Qing-chen, JI Wen-bin. 2012. Phanerozoic tectonothermal events of the Xuefengshan Belt, central South China: implications from UPb age and LuHf determinations of granites[J]. Lithos, 150: 243-255.

DING Xing, CHEN Pei-rong, CHEN Wei-feng, HUANG Hong-ye, ZHOU Xin-min. 2005. Single zircon LA-ICPMS U-Pb dating of Weishan granite (Hunan, South China) and its petrogenetic significance[J]. Science in China Series D: Earth Sciences, 35(7): 606-616(in Chinese).

DONG Shu-wen, ZHANG Yue-qiao, LONG Chang-xing, YANG Zheng-yu, JI Qiang, WANG Tao, HU Jian-ming, CHEN Xuan-hua. 2008. Jurassic Tectonic Revolution in China and New Interpretation of the “Yanshan Movement”[J]. Acta Geologica Sinica(English Edition), 82(2): 334-347.

FAN Wei-ming, WANG Yue-jun, GUO Feng, PENG Tou-ping. 2004. Mesozoic mafic magmatism in Hunan-Jiangxi provinces and the lithospheric extension[J]. Earth Science Frontiers, 10(3): 159-169(in Chinese with English abstract).

FU Jian-ming, MA Chang-qian, XIE Cai-fu, ZHANG Ye-ming, PENG Song-bai. 2004. Zircon SHRIMP dating of Ciling granite on the eastern margin of the Qitianling granite, Hunan, South China, and its significance[J]. Geology in China, 31(1): 96-100(in Chinese with English abstract).

GRIFFIN W L, BELOUSOVAL E A, SHEE S R, PEARSON N J, OEILLY S Y. 2004. Archean crustal evolution in the northern Yilgarn Craton: U–Pb and Hf-isotope evidence from detrital zircons[J]. Precambrian Research, 131(3): 231-282.

GUO Fu-xiang. 1999. Folding of cover of South China platform and its folding age[J]. Geology and Prospecting, 35(4): 5-7(in Chinese with English abstract).

LI Hua-qin, LU Yuan-fa, WANG Deng-hong, CHEN Yu-chuan, YANG Hong-mei, GUO Jing, XIE Cai-fu, MEI Yu-ping, MA Li-yan. 2006. Dating of the Rock-forming and Ore-froming Ages and Their Geological Signif icances in the Furong Ore-field, QitianMountain, Hunan[J]. Geological Review, 52(1): 113-121(in Chinese with English abstract).

LI Jian-hua, ZHANG Yue-qiao, DONG Shu-wen, SU Jin-bao, LI Yong, CUI Jian-Jun, SHI Wei. 2013. The Hengshan low-angle normal fault zone: Structural and geochronological constraints on the Late Mesozoic crustal extension in South China[J]. Tectonophysics, http://dx.doi.org/10.1016/j.tecto.2013.05.013.

LI Jian-hua, ZHANG Yue-qiao, XU Xian-bing, LI Hai-long, DONG Shu-wen, LI Ting-dong. 2014. SHRIMP U-PB Dating of Zircons from the Baimashan Longtan Super-Unit and Wawutang Granites in Hunan Province and Its Geological Implication[J]. Journal of Jilin University(Earth Science Edition), 44(01): 158-175(in Chinese with English abstract).

LI Jin-dong, BAI Dao-yuan, WU Guang-ying, CHE Qin-jian, LIU Hui-rong, MA Tie-qiu. 2005. Zricon SHRIMP dating of the Qitianling granite, Chenzhou, southern Hunan, and its geological significance[J]. Geoloical Bulletin of China, 24(5): 411-414(in Chinese with English abstract).

LI Si-guang. 1973. Introduction to Geomechanics[M]. Beijing: Science Press(in Chinese).

LI Xian-hua, LI Zheng-xiang, LI Wu-xian, LIU Ying, YUAN Chao, WEI Gang-jian, QI Chang-shi. 2007. U–Pb zircon, geochemical and Sr-Nd-Hf isotopic constraints on age and origin of Jurassic I- and A-type granites from central Guangdong, SE China: A major igneous event in response to foundering of a subducted flat-slab?[J]. Lithos, 96(1-2): 186-204.

LI Zheng-xiang, LI Xian-hua, WARTHO J A, CLARK C, LI Wu-xian, ZHANG Chuan-lin, BAO Chao-min. 2010. Magmatic and metamorphic events during the early Paleozoic Wuyi-Yunkai orogeny, southeastern South China: New age constraints and pressure-temperature conditions[J]. Geological Society of America Bulletin, 122(5-6): 772-793.

LI Zheng-xiang, LI Xian-hua. 2007. Formation of the 1300-km-wide intracontinental orogen and postorogenic magmatic province in Mesozoic South China: A flat-slab subduction model[J]. Geology, 35: 179-182.

LIU Yao-rong, KUANG Jun, MA Tie-qiu, BAI Dao-yuan. 2005.40Ar-39Ar dating of biotitie in south Dayishan granite and its geological significance[J]. Resources Survey & Environment, 26(4): 244-249(in Chinese with English abstract).

LUO Zhi-gao, WANG Yue-jun, ZHANG Fei-fei, ZHANG Ai-mei, ZHANG Yu-zhi. 2010. LA-ICPMS Zircon U-Pb Dating for Baimashan and Jintan Indosinian Granitic P lutons and Its Petrogenetic Implications[J]. Geotectonicaet Metallogenia, 34(2): 282-290(in Chinese with English abstract).

MA Tie-qiu, BAI Dao-yuan, KUANG Jun, WANG Xian-hui. 2005. Zircon SHRIMP dating of the Xitian granite pluton, Chaling, southeastern Hunan, and its geological significance[J]. Geoloical Bulletin of China, 24(5): 415-419(in Chinese with English abstract).

METCALFE I. 2013. Gondwana dispersion and Asian accretion: Tectonic and palaeogeographic evolution of eastern Tethys[J]. Journal of Asian Earth Sciences, 66: 1-33.

METCALFE I. 2011. Tectonic framework and Phanerozoic evolution of Sundaland[J]. Gondwana Research, 19(1): 3-21.

MORLEY C K, AMPAIWAN P, THANUDAMRONG S, KUENPHAN N, WARREN J. 2012. Development of the Khao Khwang Fold and Thrust Belt: Implications for the geodynamic setting of Thailand and Cambodia during the Indosinian Orogeny[J]. Journal of Asian Earth Sciences, 62: 705-719.

PENG Bing-xia, WANG Yue-jun, FAN Wei-ming, PENG Tou-ping, LIANG Xin-quan. 2006. LA-ICPMS Zircon U-Pb Dating for Three Indosinian Granitic Plutons from Central Hunan and Western Guangdong Provinces and Its Petrogenetic Implications[J]. Acta Geologica Sinica, 80(5): 660-669.

QIU Jian-sheng, LIU Liang, LI Zhen. 2011. Zircon U-Pb geochronology and Sr-Nd-Hf isotopic geochemistry of quartz syenite from Wanghaigang pluton in Huangyan County, Zhejiang Province and their implications for petrogenesis[J]. Acta Petrologica Sinica, 27(6): 1557-1572(in Chinese with English abstract).

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.

SHU Liang-shu. 2012. An analysis of principal features of tectonic evolution in South China Block[J]. Geoloical Bulletin of China, 31(7): 1035-1053(in Chinese with English abstract).

SONG Biao, ZHANG Yu-hai, WAN Yu-sheng, JIAN Ping. 2002. Mount Making and Procedure of the SHRIMP Dating[J]. Geological Review, 48(1): 26-30(in Chinese with English abstract).

SUN Yang, MA Chang-qian, LIU Yuan-yuan, SHE Zhen-bing. 2011. Geochronological and geochemical constraints on the petrogenesis of late Triassic aluminous A-type granites in southeast China[J]. Journal of Asian Earth Sciences, 42(6): 1117-1131.

WANG Qing-chen. 2009. Preliminary Discussion on Sedimentary Tectonics of the Clustered Continents of South China[J]. Acta Sedimentologica Sinica, 27(5): 811-817(in Chinese with English abstract).

WANG Yue-jun, FAN Wei-ming, ZHANG Guo-wei, ZHANG Yan-hua. 2013. Phanerozoic tectonics of the South China Block: key observations and controversies[J]. Gondwana Research, 23(4): 1273-1305.

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 Yue-jun, FAN Wei-ming, LIANG Xin-quan, PENG Tou-ping, SHI Yu-ruo. 2005. SHRIMP zircon U-Pb geochronology of Indosinian granites in Hunan Province and its petrogenetic implications[J]. Chinese Science Bulletin, 50(13): 1259-1266(in Chinese).

WU Guang-ying, PAN Zhong-fang, LI Jin-dong, XIAO Qing-hui, CHE Qin-jian. 2005. Geological and geochemical characteristiscs of the Dayishan granitoids in southern Hunan and their relations to mineralization[J]. Geology in China, 32(3): 434-442(in Chinese with English abstract).

WU Guang-ying, PENG He-qiu, JIA Bao-hua. 2000. Geological features and emplacement mechanism of the Dayishan granitic intrusion in south Hunan[J]. Geology and Mineral Resources of south China, (3): 1-7(in Chinese with English abstract).

WU Yuan-bao, ZHENG Yong-fei. 2013. Tectonic evolution of a composite collision orogen: An overview on the Qinling-Tongbai-Hong'an-Dabie-Sulu orogenic belt in central China[J]. Gondwana Research, 23: 1402-1428.

XU Xian-bing, ZHANG Yue-qiao, JIA Dong, SHU Liang-shu, WANG Rui-rui. 2009. Early Mesozoic geotectonic processes in South China[J]. Geology in China, 36(3): 573-593(in Chinese with English abstract).

YUAN Yu-Song, MA Yong-Sheng, HU Sheng-Biao, GUO Tong-Lou, FU Xiao-Yue. 2006. Present-day geothermal characteristics in South China[J]. Chinese Journal of Geophysics, 49(4): 1118-1126(in Chinese with English abstract).

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

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(1): 234-247(in Chinese with English abstract).

ZHAO Kui-dong, JIANG Shao-yong, CHEN Wei-feng, CHEN Pei-Rong, LING Hong-fei. 2013. Zircon U-Pb chronology and elemental and Sr-Nd-Hf isotope geochemistry of two Triassic A-type granites in South China: Implication for petrogenesis and Indosinian transtensional tectonism[J]. Lithos, 160: 292-306.

ZHAO Kui-dong, JIANG Shao-yong, JIANG Yao-hui, LIU Dun-yi. 2006. SHRIMP U-Pb dating of the Furong unit of Qitianling granite from southeast Hunan province and their geoloical inplications[J]. Acta Petrologica Sinica, 22(10): 2611-2616(in Chinese with English abstract).

ZHAO Yue, XU Gang, ZHANG Shuan-hong, YANG Zhen-yu, ZHANG Yue-qiao, HU Jian-min. 2004. Yanshanian movement and conversion of tectonic regimes in East Asia[J]. Earth Science Frontiers, 11(3): 319-328(in Chinese with English abstract).

ZHOU Ji-bin, LI Xian-hua, GE Wen-chun, LI Zheng-xiang. 2007. Age and origin of middle Neoproterozoic mafic magmatism in southern Yangtze Block and relevance to the break-up of Rodinia[J]. Gondwana Research, 12(1): 184-197.

ZHOU X M, LI W X. 2000. Origin of Late Mesozoic igneous rocks in Southeastern China: implications for lithosphere subduction and underplating of mafic magmas[J]. Tectonophysics, 326(3): 269-287.

ZHOU Xin-min, SUN Tao, SHEN Wei-hou, SHU Liang-shi, 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.

ZHU Guang, LIU Guo-sheng, NIU Man-lan, XIE Cheng-long, WANG Yong-sheng, XIANG Bi-wei. 2009. Syn-collisional transform faulting of the Tan-Lu fault zone, East China[J]. International Journal of Earth Sciences, 98(1): 135-155.

ZHU Jin-chu, WANG Ru-cheng, ZHANG Pei-hua, XIE Cai-fu, ZHANG Wen-lan, ZHAO Kui-dong, XIE Lei, YANG Ce, CHE Xu-dong, YU A-peng, WANG Lu-bin. 2009. Zircon U-Pb geochronological framework of Qitianling granite batholith, middle part of Nanling Range, South China[J]. Science in China Series D: Earth Sciences, 52(9): 1279-1294.

Zircon U-Pb Dating of Dayishan and Tashan Plutons in Hunan Province and Its Tectonic Implications

LI Yong1,2), ZHANG Yue-qiao2), SU Jin-bao3), LI Jian-hua2), DONG Shu-wen4)*
1) Peking Universty, Beijing 100871; 2) Institute of Geomechanics, Chinese Academy of Geologicl Scienses, Beijing 100081; 3) Hohai University, Nanjing, Jiangsu 210098; 4) Chinese Academy of Geologicl Scienses, Beijing 100037

The distribution and intrusion of Early Mesozoic granites in central South China such as Dayishan pluton and Tashan pluton are closely related to folded structure in this region. Precise chronologic studies can constrain the age of the tectonic deformation. This paper report zircon U-Pb LA-ICP-MS ages of the southern part of Dayishan pluton based on dating of 3 samples: the age of the eastern margin is (171.8±1.9) Ma, that of the western margin is (169.9±1.8) Ma and that of the central part is (164.2±2.6) Ma. The zircon U-Pb LA-ICP-MS age of the eastern part of Tashan pluton is (247±5.9) Ma. Dayishan pluton experienced two phases of intrusion between 164.2 and 171.8 Ma and formed a composite pluton; after that, it experienced rapid uplift prior to 125 Ma, and then it was rapidly raised to the surface at the cooling rate of 1°C/Ma. Dayishan pluton and Tashan pluton recorded Indosinian and Yanshanian magmatic activities. The EW-trending structural zone controlled Indosinian granites, such as Yangmingshan and Tashan; the ages of Dayishan and Qitianling plutons constrain the Yanshanian tectonic deformation, and the formation of the NNE-trending folds in South China should be earlier than (171.8±1.9) Ma.

South China; Dayishan pluton; Tashan pluton; zircon U-Pb age

P588.121; P597.1

A

10.3975/cagsb.2015.03.05

本文由财政部“深部探测技术与实验研究”专项之子课题(编号: Sinoprobe-08-01)资助。

2014-10-08; 改回日期: 2014-11-31。责任编辑: 闫立娟。

李勇, 男, 1980年生。博士研究生。构造地质学专业。E-mail: colyly@163.com。

董树文, 男, 1954年生。研究员, 博士生导师。长期从事构造地质和深部地质研究, 近年来重点探讨燕山运动和东亚大陆地球动力学问题。E-mail: swdong@cags.ac.cn。