img img
高级检索
地球科学进展, 2018, 33(9): 945-957
doi: 10.11867/j.issn.1001-8166.2018.09.0945
大别造山带内部变沉积岩锆石LA-ICP MS U-Pb定年及其大地构造意义
LA-ICP MS Zircon U-Pb Dating of Metasedimentary Rocks in Dabie Orogenic Belt and Its Tectonic Implications
田自强1,, 王勇生1,*,, 胡召齐2, 白桥1
1.合肥工业大学资源与环境工程学院,安徽 合肥 230009
2.安徽省地质调查院,安徽 合肥 230001
Tian Ziqiang1,, Wang Yongsheng1,*,, Hu Zhaoqi2, Bai Qiao1
1.School of Resources and Environmental Engineering, Hefei University of Technology, Hefei 230009, China
2.Geological Survey of Anhui Province, Hefei 230001, China
 引用本文:
田自强, 王勇生, 胡召齐, 白桥. 大别造山带内部变沉积岩锆石LA-ICP MS U-Pb定年及其大地构造意义[J]. 地球科学进展, 2018, 33(9): 945-957, doi:10.11867/j.issn.1001-8166.2018.09.0945
Tian Ziqiang, Wang Yongsheng, Hu Zhaoqi, Bai Qiao. LA-ICP MS Zircon U-Pb Dating of Metasedimentary Rocks in Dabie Orogenic Belt and Its Tectonic Implications[J]. Advances in Earth Science, 2018, 33(9): 945-957, doi:10.11867/j.issn.1001-8166.2018.09.0945

摘要:

大别造山带内部零星出露有浅变质岩,其与造山带其他单元内高级变质岩的共生状态可以为造山带的演化过程提供信息。北大别单元东北缘沈桥地区出露有浅变质岩。为了获取该浅变质岩的形成时间、物源信息及与北大别单元岩石之间的接触关系,在详细的野外观察基础上,对出露于沈桥地区的浅变质岩进行了详细的显微鉴定和碎屑锆石LA-ICP MS U-Pb定年。研究发现,沈桥地区浅变质岩具有与佛子岭群诸佛庵岩组一致的岩石学特征,碎屑锆石的最小年龄为431 Ma,年龄频谱特征与佛子岭群变沉积岩一致,表明沈桥地区浅变质岩为佛子岭群的一部分。显微鉴定表明,沈桥变沉积岩中石英动态重结晶型式均表现为完全的亚颗粒旋转(SGR)重结晶,黑云母具有明显的生长边,表明在其形成过程中曾经历了绿帘—角闪岩相变质—变形事件;变沉积岩在露头上显示的韵律层在沉积岩原岩形成时就已经存在,之后经过浅变质作用,岩石中的矿物相发生了改变:原岩中的泥质层变质为颜色较深的层状黑云母,砂质层变质为颜色较浅的动态重结晶石英。

关键词: 大别造山带 ; 变沉积岩 ; 锆石定年 ; 构造演化

Abstract:

Low-grade metamorphic rocks concentrated in the Beihuaiyang unit and were sporadically in other units of the Dabie orogenic belt, whose coexistence with other rocks in the orogenic belt can provide evidence for the evolution of the Dabie orogenic belt. A small number of metasedimentary rocks crop out in the Shenqiao area, northeast of the North Dabie unit. In order to obtain the forming age and provenance of the low-grade metamorphic rocks and their relationship with the rocks in the North Dabie unit, detailed field observations, systematic microscopic identification and detrital zircon LA-ICP MS U-Pb dating were presented for metasedimentary rocks in the Shenqiao area. The results show that metasedimentary rocks in the Shenqiao area have similar petrological characteristics as low-grade metamorphic rocks of the Zhufoan Formation in the Foziling Group. The minimum age of detrital zircon is 431 Ma, which is also similar as the Foziling Group. All these reveal that these low-grade metamorphic rocks in the Shenqiao area may be a part of the Foziling Group. Detailed observations on thin-sections show that quartz are characterized by Subgrain Rotation (SGR) recrystallization and biotite has obvious growth rims, which indicates that the metasedimentary rocks experience an epidote-amphibolite facies metamorphic and deformation event. The rhythmic layers on the outcrop existed before experiencing low-grade metamorphism, during which the argillaceous layer in the protolith transferred to the darker layered biotite and the sandy layer to lighter and recrystallized quartz.

Key words: Dabie orogenic belt ; Metasedimentary rocks ; Zircon U-Pb dating ; Tectonic evolution.
1 引 言

大别造山带是三叠纪华南、华北板块陆—陆碰撞缝合边界的一部分,由于出露了大面积超高压变质岩石而受到广泛关注[1,2,3,4,5,6]。大别造山带内出露了大量的浅变质岩,由变沉积岩或变火山岩组成[5,7,8],主要分布在造山带北缘的北淮阳单元内,少量在造山带内部零星出露,为造山带的重要组成部分。现有的研究表明,北淮阳单元内佛子岭群为形成于早古生代的变沉积岩[9,10,11],仅经历了浅变质作用[5,8]。因而,这些浅变质岩石可能记录了造山带深俯冲之前的构造演化信息,尤其是出露于造山带内部、与高级变质岩共生在一起的浅变质岩,其赋存状态可以很好地为浅变质岩在造山作用中的构造演化过程提供信息。岳西港河地区与超高压榴辉岩共生在一起的变火山岩仍很好地保留了火山岩组构特征[5,12~15],虽然被解释为以亚稳态状态与榴辉岩共生,但仍存在较大的争议[16]。而该变火山岩形成于800~760 Ma[15,17,18],与北淮阳单元内出露的形成于早古生代的变沉积岩明显不同[9,10,11]。因而,港河地区变火山岩是否与北淮阳单元内变沉积岩具有相同的演化历史仍需更多的工作来证明。

北大别单元内沈桥地区也出露有浅变质岩[5],具有与北淮阳单元变沉积岩类似的韵律层特征。该浅变质岩出露于北大别单元内,如果其具有与北淮阳单元变沉积岩相同的成因,则其与早白垩世岩体及混合岩的共生状态如何?该问题的回答有助于解释大别造山带不同岩石—构造单元的接触关系,进而为造山带的演化过程提供信息。

基于以上问题,本次工作在详细的野外观察和显微鉴定基础上,对沈桥地区出露的浅变质岩开展LA-ICP MS锆石U-Pb微区定年,获得其形成时间,结合其产出状态和构造特征,为造山带内浅变质岩的形成演化提供信息。

2 区域地质背景

大别造山带是秦岭—大别造山带的东延部分,其东界以郯庐断裂带与下扬子地区相邻,西界以商麻断裂与红安地区相接,南侧为扬子前陆褶—冲带,北侧为合肥盆地(图1)。大别造山带岩石—构造单元自北向南可划分为北淮阳单元、北大别单元、高压—超高压榴辉岩单元及高压绿片岩相—角闪岩相单元(宿松杂岩带、张八岭群)[1,7]


图1

大别造山带岳西沈桥地区构造简图及采样位置
(a)秦岭—大别造山带索引图;(b)大别造山带及邻区构造单元划分;1:变沉积岩;2:北大别杂岩;3:主簿源岩体;4:岩脉;5:基性岩浆岩;6:韧性剪切带;7:正断层;8:岩石面理产状;9:采样位置

Fig.1

Structural map of the Shenqiao area in the Dabie orogenic belt and sampling location
(a)Sketch of the Qinling-Dabie-Sulu orogenic belts; (b) Tectonic unit of the Dabie orogenic belt and adjacent region; 1. Metasedimentary rocks;2.Complex rocks in the North Dabie unit; 3.The Zhubuyuan pluton; 4.Dykes; 5.Basic rock; 6.Ductile shear zone;7.Normal fault; 8.Foliation; 9.Sampling location

位于商麻断裂以东、晓天—磨子潭剪切带以北的北淮阳单元主要由佛子岭群、卢镇关群及少量石炭系地层构成。佛子岭群主要由浅变质的砂岩、板岩、千枚岩、云母片岩、石英岩和大理岩组成,原岩的U-Pb锆石年龄结果主要变化于2 500~400 Ma[9,10,11]。卢镇关群则主要由正片麻岩组成,部分岩石经历了绿帘—角闪岩相变质作用[19],其原岩锆石年龄为800~700 Ma[9,20~22],表明其来源于扬子陆块。佛子岭群岩石强烈揉皱变形,卢镇关群则在局部强变形带发育糜棱岩,周建波等[8]认为这些岩石为扬子板块俯冲时刮削下来的构造加积楔。长期以来,研究者们认为大别造山带的部分岩石被覆盖于合肥盆地沉积物之下,华南、华北板块的缝合线可能位于合肥盆地内近东西向的肥中断裂一带[4,19,23]。近年来,在合肥盆地内发现了分别隶属于佛子岭群和卢镇关群的石墨片岩和花岗片麻岩[10],进一步证实了上述推测。北淮阳单元是大别造山带内唯一出露大面积早白垩世火山岩的构造单元,在其南缘晓天—磨子潭剪切带北侧出现了近东西向的伸展型晓天陆相火山—碎屑岩盆地。

北大别杂岩单元是大别造山带内出露面积最大的构造—岩石单元,位于晓天—磨子潭剪切带以南、五河—水吼断裂以北的地区,主要由混合岩、灰色片麻岩和斜长角闪岩组成,并有大量的早白垩世花岗岩和少量基性—超基性岩体侵入,局部存在少量呈布丁状分布的榴辉岩、石榴辉石岩及麻粒岩。这些榴辉岩及石榴辉石岩峰期变质时间为218~209 Ma[24],并经历了T≥750~800 ℃、P约为3.5 GPa的峰期变质作用[25]。北大别单元总体表现为穹隆构造,并由位于西部的罗田穹隆与东部的岳西穹隆2个次级穹隆组成。在罗田穹隆中心部位及其北部局部发育有下地壳麻粒岩,在商麻断裂与晓天—磨子潭剪切带附近局部出露超高压榴辉岩[26,27]。北大别单元内混合岩及片麻岩具有复杂的成因,岩石中不同锆石核部存在新元古代[23]、印支期[24]和早白垩世[28,29]3种不同的年龄信息,但边部多具有清晰的早白垩世年龄信息,表明北大别单元内混合岩在早白垩世经历过一次明显的热事件。

3 样品描述及构造特征

沈桥地区位于岳西县城以北姚河乡以西,主簿源岩体的北西缘,归属于北大别单元,主要出露混合岩、二长花岗岩以及变沉积岩(图1c)。混合岩隶属于北大别单元,出露于研究区西侧,其主要倾向NE,倾角相对较缓,与前人在北大别单元内获得的岩石产状分布规律一致[30]。二长花岗岩则隶属于主簿源岩体,出露于研究区东侧,岩石中长石颗粒相对较大,多为0.5~1 cm。露头点西侧该花岗岩表现出清晰的面理特征,石英拉长现象明显(图2a),指示曾经历过剪切活动,面理产状152°∠50°。研究区花岗岩总体风化严重,具清晰面理的部位相对完整。沈桥地区变沉积岩出露于岩体西缘,岩石总体表现为青灰色、质地坚硬、发育清晰的韵律层,表现为灰黑色与青灰—灰白色相间出现(图2b),部分位置泥质含量相对较多的表现为土黄色与青灰色相间的韵律层。该特征表明岩石原岩可能以石英砂岩为主,部分位置表现为砂质泥岩和砂岩互层。而岩石保留了韵律层特征的现象,与北淮阳单元佛子岭群中诸佛庵岩组岩石总体表现一致,表明沈桥变沉积岩可能具有与佛子岭群一致的岩石学特征。变沉积岩存在于二长花岗岩中,两者之间为侵入接触关系(图2c),部分变沉积岩作为捕虏体存在于花岗岩中(图2d)。该地区变沉积岩岩石相对稳定,主要倾向NE或SW;倾角相对较小,多介于10°~20°(图1c)。并且,在变沉积岩主体出露位置旁侧,花岗岩中较大的变沉积岩捕虏体具有与主体岩石一致的面理产状。这表明沈桥地区出露的变沉积岩并不是花岗岩侵位过程中携带来的捕虏体,而是在原地被花岗岩侵入。露头岩石的接触关系应当是顶部变沉积岩被剥蚀后,其底部被花岗岩包裹的部分出露出来,从而展示出类似捕虏体的特征。


图2

大别造山带内沈桥变沉积岩野外照片和显微照片
(a)韧性变形的二长花岗岩;(b)具韵律层的变沉积岩;(c)风化的二长花岗岩与变沉积岩接触;(d)以捕虏体形式存在于二长花岗岩中的变沉积岩;(e)变形的石英及成带分布的黑云母;(f)变形的石英和具生长边的黑云母

Fig.2

Field photos and photomicrographs of metasedimentary rocks from the Shenqiao area in the Dabie orogenic belt
(a) Ductile deformed monzonitic granite; (b) Metasedimentary rocks with rhythmic texture; (c) The boundary of Weathered monzonitic granite and metasedimentary rocks; (d) Metasedimentary rocks existing in the monzonitic granite as xenolith; (e) Deformed quartz and zoned biotite in metasedimentary rocks; (f) Deformed quartz and biotite with growth edge

进行显微镜下观察的薄片均沿平行于线理、垂直面理的方向(XZ面)切片。详细的显微镜下观察发现,沈桥地区变沉积岩主要由石英、长石、黑云母组成,其中石英含量约60%,黑云母约30%,长石约10%(图2e)。岩石中石英颗粒大小基本一致,直径主要为150 μm左右,均匀分布于岩石中。岩石薄片中黑云母呈带状、较连续的平行排列分布,具有明显的定向性,分布方向与岩石面理一致;黑云母颗粒相对较小,其长轴长度与石英颗粒直径基本一致,主要为100 μm左右;岩石中黑云母具有较清晰的生长边(图2e,f),指示其为变质过程中新生的,而其较小的颗粒大小也指示岩石并没有经历角闪岩相及以上的高级变质作用。岩石中长石相对较少,颗粒大小主要为150~200 μm,可观察到清晰的聚片双晶、格子状双晶特征,表明长石由钾长石和斜长石共同组成,部分长石颗粒表面发生黏土化。根据以上特征,岩石可定名为黑云母石英片岩。

岩石中石英颗粒边界全部表现为不规则形态,指示其发生了明显的动态重结晶,也表明岩石曾发生过韧性变形。虽然石英颗粒大小均一,并不存在残斑与基质的区别,但由于石英颗粒边界相对平直,并未表现出相互勘合的港湾状形态(图2f),指示其动态重结晶型式表现为亚颗粒旋转(Subgrain Rotation, SGR)重结晶而不是颗粒边界迁移(Grain Boundary Migration, GBM)重结晶[31]。在变形温度为420~480 ℃时,石英以独立的SGR重结晶存在[32],因而石英的动态重结晶型式表明岩石曾经历了温度为420~480 ℃的韧性变形。另外,岩石中存在大量黑云母,但并没有绿泥石出现,表明岩石韧性变形时的温度条件应高于绿片岩相。绿片岩相与绿帘角闪岩相环境的界限温度为450 ℃。结合石英的变形型式,可以得出岩石的变形温度主要为450~480 ℃。

4 锆石LA-ICP MS微区定年
4.1 测试方法

为了获取岩石的形成时间,本次工作在沈桥变沉积岩中采集样品挑选锆石进行LA-ICP MS U-Pb年龄测定。用于锆石年代学测试的样品首先在河北省廊坊区域地质调查研究所采用常规方法进行粉碎,并用浮选和电磁选方法进行分选,挑选出单颗粒锆石;然后在双目镜下挑选出晶形和透明度较好的锆石颗粒,将它们粘贴在环氧树脂表面;经抛光后进行透射光和反射光照相,据此选择晶体特征良好的锆石进行阴极发光照射(部分图像如图3所示);最后根据阴极发光照射结果选择典型的锆石颗粒进行U-Pb年代学测试。

锆石原位U-Pb 同位素和微量元素分析在合肥工业大学资源与环境工程学院质谱实验室开展,使用激光—电感耦合等离子质谱仪(LA-ICPMS)完成,激光剥蚀系统为德国 Microlas 公司生产的GEOLAS,测试质谱仪为 Agilent 7 500 a,详细的仪器操作条件参阅参考文献[33]。U-Pb同位素定年中采用锆石标准91500作外标进行同位素分馏校正。数据处理采用中国地质大学(武汉)开发的ICPMSDataCal 8. 0软件完成,选取谐和度≥90%的样品点进行数据分析,采用 Isoplot软件[34]绘制谐和图、年龄分布频谱图并计算加权平均年龄。分析结果见表1

表1

大别造山带沈桥地区变沉积岩锆石LA-ICP MS U-Pb定年结果

Table 1

Zircon LA-ICP MS U-Pb analysis results of metasediment from the Shenqiao area in the Dabie orogenic belt

4.2 测试结果

沈桥变沉积岩中锆石粒度大小不一,长度最小 50 μm,最大可达 200 μm;形状差异较大,部分锆石呈自形,多数锆石呈半自形、他形,总体上显示了碎屑锆石的特征(图3)。阴极发光图像显示,大多数锆石发育振荡环带或板状构造,Th/U比值明显大于 0.1(0.21~2.24,表1),表明这些锆石主体为岩浆锆石[35]。对样品所挑选的锆石随机选取点位进行LA-ICP MS定年分析,去除信号不好、207Pb/235U相对于206Pb/238U偏差较大的年龄数据,对于年龄小于1.0 Ga的锆石取206Pb/238U年龄,大于1.0 Ga的锆石取207Pb/206Pb年龄,获得谐和度≥90%的数据结果96个(n=96)。年龄结果为380~3 529 Ma,所有锆石测点的3个表面年龄值207Pb/206Pb、207Pb/235U、206Pb/238U在误差范围内基本一致(表1),表明年龄数据可信度较高。锆石年龄数据结果主要集中于400~1 100 Ma,存在6个年龄集中区,对应峰值年龄依次为445,529,605,747,841和971 Ma(图3)。大于1 100 Ma的年龄结果分布相对稀疏,3个主要的年龄集中区对应的峰值年龄分别为1 574,1 912和2 414 Ma。


图3

沈桥变沉积岩碎屑锆石U-Pb年龄谐和图、年龄分布频谱图及Th/U比

Fig.3

Zircon U-Pb concordia diagram, histogram and Th/U ratio for the metasedimentary rocks from the Shenqiao area

5 大别造山带内变沉积岩的形成演化
5.1 变沉积岩的形成时间及物源分析

本次工作定年结果表明,沈桥地区浅变质岩年龄结果表现出典型的碎屑锆石特征,并且岩石学特征也表明其原岩为沉积岩,因而沈桥地区出露的浅变质岩应为变沉积岩。通常碎屑锆石年龄结果中最小的年龄值被用来限定岩石的形成时间[36]。本次定年工作在沈桥变沉积岩中获得最小锆石年龄为380 Ma,但由于该年龄结果仅有一个,且与其他年龄结果相差较大(表1),因而本次工作选择采用较为集中年龄值的最小结果(431 Ma)来限定沈桥变沉积岩的原岩形成的最早时间,该年龄值表明其形成时间为早古生代。

近年来,碎屑锆石年龄已成为追踪沉积物物源的重要工具[36,37,38]。与前人对佛子岭群变沉积岩的碎屑锆石定年结果相比,沈桥变沉积岩除具有与佛子岭群岩石最小碎屑锆石年龄以外,还与其年龄频谱分布特征几乎完全一致,均清楚地显示了0.5~0.4,0.8~0.7,1.0~0.9,2.0~1.8以及2.4 Ga左右的年龄峰值特征[9,10,11],表明其与北淮阳单元内佛子岭群具有相同的物源及成因(图4)。其中2.0~1.8 Ga峰值对应于哥伦比亚超大陆聚合形成的特征年龄值,在华北板块内广泛分布[56],但在华北板块南部缺失[57],而华南板块内该时间段锆石年龄值的存在[58]指示这些锆石可能来自于华南板块。1.0~0.9 Ga峰值对应于罗迪尼亚超大陆聚合、Grenville造山带形成的特征年龄值[59],最新的研究表明秦岭—大别造山带内可能存在从扬子板块北缘分裂出来的、具有典型的1.0~0.9 Ga岩浆锆石年龄的微陆块[11],提供了该时代锆石的来源。0.8~0.7 Ga峰值对应于罗迪尼亚超大陆裂解过程中裂谷岩浆岩的形成时间[60,61]。0.5~0.4 Ga是全球早古生代晚期造山作用的特征年龄[62],在大别造山带内被解释为华南板块向北淮阳微陆块下俯冲形成的弧岩浆岩年龄[11]。而由于大别造山带内并没有该时代弧岩浆岩出露,以往的研究常被认为这些碎屑锆石来源于秦岭[63]


图4

沈桥变沉积岩周边地区锆石年龄频谱特征
佛子岭群年龄数据据参考文献[9,10,11];华北克拉通东南缘年龄数据据参考文献[39,40,41,42,43,44,45,46];扬子板块数据据参考文献[47,48,49,50,51,52,53,54,55]

Fig.4

Compilations of concordant zircon U-Pb ages around the metasedimentary rocks in the Shenqiao area
The age data of the Foziling Group from references[9~11], the southeastern North China Block from references[39~46] and the Yangtze Block from references[47~55]

与前人年龄结果略有差别的是,本次工作中获得了10个0.6~0.5 Ga的年龄结果(618~509 Ma,表1),峰值年龄为529和605 Ma。这些锆石均具有清晰的震荡环带,年龄谐和度明显高于90%,且在定年过程中并未出现多个环带混合的现象(图3),因而能够代表锆石的形成时间。该年龄结果对应于泛非事件,向磊等[64]曾在华南东段赣南地区泥盆纪和奥陶纪粗碎屑岩中获得了650~520 Ma的年龄结果,但到目前为止,在华南板块地表并未发现相应的岩浆岩分布。而该年龄结果的获得显示泛非事件形成的岩浆岩可能在华南板块曾零星出露。

根据以上分析可知,虽然现今沈桥变沉积岩位于晓天—磨子潭剪切带以南,并不与佛子岭群出露位置相连,但其应当隶属于佛子岭群变沉积岩的一部分。这可能是在大别造山带早白垩世穹隆活动过程中,由于位于北大别单元北侧的晓天—磨子潭剪切带的正断活动,使剪切带以南的变沉积岩基本剥蚀殆尽,仅在靠近剪切带南侧附近少量残留,呈孤岛状分布于北大别单元中。

5.2 造山带内变沉积岩产出位置的指示

以往的研究认为,北淮阳单元中佛子岭群主要经历了绿片岩相变质作用,部分卢镇关群正片麻岩经历了绿帘角闪岩相变质作用[5,19]。本次工作发现,沈桥变沉积岩存在大量的新生黑云母,但并没有绿泥石存在,表明其变质—变形环境应为绿帘—角闪岩相,这也得到了岩石中石英变形特征的证明(图2f)。

野外露头上观察到的岩石韵律层则是岩石中矿物成分差异所导致的,其中颜色较深的条带是因为含有较多的黑云母,而颜色较浅者则主要由石英构成。岩石中矿物成层分布的特征应与原始沉积的物质层密切相关,云母层对应于原岩中的泥质成份层,石英层则对应于石英砂岩层,这可能是露头上岩石成分层的分布被当作沉积韵律层的原因。而该对应关系的存在也很好地指示了沈桥变沉积岩并没有经历高等级的变质作用。虽然本次工作并没有对直接出露于北淮阳单元内的佛子岭群岩石开展研究,但沈桥变沉积岩属于佛子岭群的一部分,因而沈桥变沉积岩的变质环境也代表了佛子岭群的变质环境。

沈桥地区变沉积岩呈捕虏体存在于主簿源岩体中(图1,图2d),但不同捕虏体之间具有相近的岩石产状,表明变沉积岩在原位被花岗岩侵入。以往的研究认为主簿源岩体主体的侵位深度至少为8 km左右[28,65,66]。虽然这些变沉积岩位于主簿源岩体的西北边缘位置,且与花岗斑岩等浅成侵入岩伴生,产出位置可能相对较浅,但也说明在主簿源岩体侵位时沈桥地区曾存在几公里厚的变沉积岩。

值得注意的是,与变沉积岩直接接触的主簿源岩体隶属于北大别单元,其西侧的混合岩也是北大别单元的主要岩石类型,早白垩世时北大别单元与浅变质岩之间并不存在其他岩石单元。这种现象的形成存在2种可能的原因:①大别造山带在折返过程结束后北大别单元就与浅变质岩直接接触在一起;②在造山带折返结束至早白垩世岩浆侵位之间,还存在其他的构造事件导致中间岩石单元缺失。现有的研究认为,大别造山带折返过程结束后,一系列岩片的叠置关系为北大别单元位于最下方,向上依次为超高压榴辉岩、高压榴辉岩、宿松杂岩及张八岭群,浅变质岩位于最上层[67,68,69],在早白垩世穹窿活动过程中形成以北大别单元为中心,其他单元由深及浅向南依次分布的空间展布特征。显然,沈桥地区浅变质变沉积岩与北大别单元直接接触可能受控于后期的构造事件。

北大别单元岩石自形成以来经历了多期变质事件[70],但在早白垩世之前均处于角闪岩相及以上的环境中,与佛子岭群浅变质的温度环境明显不同,表明早白垩世之前两者不可能直接接触在一起。早白垩世初,大别造山带发生后碰撞阶段穹窿抬升[28,65,66],形成位于混合岩顶部的平缓拆离断层。该拆离断层的活动及随后的岩浆侵位导致的隆升,导致北大别单元顶部的岩石几乎剥蚀殆尽,在此过程中,沈桥浅变质岩与北大别单元之间的岩石被切除,导致早白垩世岩体与浅变质岩直接接触,而混合岩则位于浅变质岩旁侧。现今露头上的岩石特征可能就是早白垩世大别造山带伸展拆离和穹窿抬升的结果,主簿源岩体与混合岩接触位置发生的正断剪切变形(图2a)则很好地证明了上述推论。这也说明该地区大规模伸展事件的发生时间应晚于混合岩的形成时间,可能与主簿源岩体的侵位有关。

北大别东缘郯庐断裂带内全岩40Ar-39Ar年龄与白云母40Ar-39Ar年龄一致[71](128 Ma左右),但由于全岩40Ar-39Ar年龄是多种不同封闭温度含钾矿物的混合年龄,因而单矿物和全岩40Ar-39Ar年龄的一致性表明128 Ma左右郯庐断裂带经历了快速的伸展活动,该伸展活动与大别造山带的隆升密切相关[72]。结合桐城高压块体在造山后伸展过程中残留于北大别单元东侧的现象[6],大别造山带在早白垩世存在大幅度的隆升活动,其隆升时间可能为128 Ma左右。

6 结 语

基于详细的野外观察和岩石学工作,本次研究对沈桥变沉积岩开展了详细的显微镜下鉴定和锆石LA-ICP MS U-Pb定年工作,得到了一些新认识:

(1)沈桥变沉积岩具有与佛子岭群一致的岩石学特征和碎屑锆石年龄坪谱分布特征,表明其属于佛子岭群的一部分,为佛子岭群在造山后隆升过程中造山带内部的残留部分。

(2)沈桥变沉积岩中石英动态重结晶型式均表现为完全的SGR重结晶,新生矿物全部为黑云母而不存在绿泥石,指示其主要经历了绿帘—角闪岩相变质—变形事件。

(3)变沉积岩在露头上显示的韵律层在沉积岩原岩形成时就已经存在,之后经过浅变质作用,岩石中的矿物相发生了改变:原岩中的泥质层变质为颜色较深的呈带状分布的黑云母,砂质层变质形成颜色较浅的动态重结晶石英。

致 谢:锆石定年得到了合肥工业大学质谱实验室李全忠副教授的帮助,在此表示衷心的感谢!

The authors have declared that no competing interests exist.

参考文献

[1]
Zhai Mingguo, Cong Bolin, Zhao Zhongyan, et al.Petrological-tectonic units in the coesite-bearing metamorphic terrain of the Dabie Mountains, central China and their geotectonic implication[J]. Journal of Southeast Asian Earth Sciences, 1995, 11(1):1-13.
[本文引用: 2]
[2]
Hacker B R, Ratschbacher L, Webb L, et al.Exhumation of ultrahigh-pressure continental crust in east central China: Late Triassic-Early Jurassic tectonic unroofing[J]. Journal of Geophysical Research, 2000,105(B6): 13 339-13 364.
[本文引用: 1]
[3]
Li Shuguang, Jagoutz E, Chen Yizhi, et al.Sm-Nd and Rb-Sr isotopic chronology and cooling history of ultrahigh pressure metamorphic rocks and their country rocks at Shuanghe in the Dabie Mountains, Central China[J]. Geochimica et Cosmochimica Acta, 2000, 64(6): 1 077-1 093.
[本文引用: 1]
[4]
Faure M, Lin Wei, Schärer U, et al.Continental subduction and exhumation of UHP rocks: Structural and geochronological insights from the Dabieshan (East China)[J]. Lithos, 2003, 70(3/4):213-241.
[本文引用: 2]
[5]
Zheng Yongfei, Zhou Jianbo, Wu Yuanbao, et al.Low-grade metamorphic rocks in the Dabie-Sulu orogenic belt: A passive-margin accretionary wedge deformed during continent subduction[J]. International Geology Review, 2005, 47(8): 851-871.
[本文引用: 6]
[6]
Lin Wei, Shi Yonghong, Wang Qingchen.Exhumation tectonics of the HP-UHP orogenic belt in Eastern China: New structural- petrological insights from the Tongcheng massif, Eastern Dabieshan[J]. Lithos, 2009, 109(3/4): 285-303.
[本文引用: 2]
[7]
Xu Shutong, Jiang Laili, Liu Yican, et al.Tectonic framework and evolution of the Dabie Mountains in Anhui, Eastern China[J]. Acta Geologica Sinica, 1992, 5(3):221-238.
URL
[徐树桐, 江来利, 刘贻灿, . 大别山区(安徽部分)的构造格局和演化过程[J]. 地质学报, 1992, 66(1):1-14.]
URL
[本文引用: 2]
[8]
Zhou Jianbo, Zheng Yongfei, Li Long, et al.Accretionary wedge of the subduction of the Yangtze plate[J]. Acta Geologica Sinica, 2001, 75(3):338-352.
Magsci URL
在总结大洋板块俯冲形成加积楔的基础上,对大别-苏鲁造山带内部及北缘浅变质岩进行了系统的研究,指出它们是扬子大陆板块俯冲的构造加积楔,这些浅变质岩既有产出在造山带北缘,也有少量出露在超高压变质带的内部,它们均形成于前印支期扬子板块北缘,主体为低绿片岩相变质的复理石相沉积岩和少量侵入岩,并遭受了与造山带超高 为质岩相同的加里东-印支期构造热事件的改造,具有板块俯冲过程中被刮削下来的构造残睛-加积楔的形成机制和特征。垂向剖面上,这些浅变质岩原岩主要由表层浅海复理石相沉积岩系和下伏陆壳基底岩石(花岗质侵入体-变质中基性杂-岩大理岩组合)两部分组成,而超高压变质岩原岩主要为扬子板块北缘的俯冲击壳基底岩石,将构造加积楔形成理论纳入到印支期扬了变质岩及构造加积楔形成过程的时空耦合关系,确定子扬子板块俯冲加积楔不同构造部位浅变质岩的构造组合特点,探讨了扬子板块俯冲过程中构造加积楔形成的动力学过程。
[周建波, 郑永飞, 李龙,. 扬子板块俯冲的构造加积楔[J]. 地质学报, 2001, 75(3):338-352.]
Magsci URL
在总结大洋板块俯冲形成加积楔的基础上,对大别-苏鲁造山带内部及北缘浅变质岩进行了系统的研究,指出它们是扬子大陆板块俯冲的构造加积楔,这些浅变质岩既有产出在造山带北缘,也有少量出露在超高压变质带的内部,它们均形成于前印支期扬子板块北缘,主体为低绿片岩相变质的复理石相沉积岩和少量侵入岩,并遭受了与造山带超高 为质岩相同的加里东-印支期构造热事件的改造,具有板块俯冲过程中被刮削下来的构造残睛-加积楔的形成机制和特征。垂向剖面上,这些浅变质岩原岩主要由表层浅海复理石相沉积岩系和下伏陆壳基底岩石(花岗质侵入体-变质中基性杂-岩大理岩组合)两部分组成,而超高压变质岩原岩主要为扬子板块北缘的俯冲击壳基底岩石,将构造加积楔形成理论纳入到印支期扬了变质岩及构造加积楔形成过程的时空耦合关系,确定子扬子板块俯冲加积楔不同构造部位浅变质岩的构造组合特点,探讨了扬子板块俯冲过程中构造加积楔形成的动力学过程。
[本文引用: 3]
[9]
Chen Fukun, Guo Jinghui, Jiang Laili, et al.Provenance of the Beihuaiyang lower-grade metamorphic zone of the Dabie ultrahigh-pressure collisional orogen, China: Evidence from zircon ages[J]. Journal of Asian Earth Sciences, 2003, 22(4): 343-352.
[本文引用: 6]
[10]
Shi Yonghong, Shen Cheng, Wang Juan, et al.Analysis of petrology, geochronology for Beihuaiyang metamorphic unit, and discussion about the suture of Dabie Orogen[J]. Chinese Journal of Geology, 2014, 49(2): 378-393.
DOI:10.3969/j.issn.0563-5020.2014.02.004 Magsci URL
Up to now,the concreted location of the suture of Dabie Orogen is still ambiguous and more controversial. In this study,the bearing-graphite quartz schists and granitic gneisses have been inspected carefully across Fang Hushan(FHS)-Shu Cheng(SC) area in the most-north of Dabie Orogen. According to the analysis from petrology and geochronology,the conditions for the schists in the FHS are =300 ℃~450 ℃ and =0.2~0.7 GPa,and in the range of green-schist facies,while four groups of detrital zircons U-Pb ages for these schists have been distinguished: 1)2 465~1 522 Ma(5 grains); 2)1 140~938 Ma(14 grains); 3)804~646 Ma(4 grains); 4)460~422 Ma(14 grains). Other,zircon U-Pb ages from two granitic gneisses in the SC are 767.9±7.8 Ma and 770±16 Ma,respectively,and these gneisses have been formed in the range of 600 ℃~700 ℃ and 0.2~0.8 GPa. Hence,these two types of rocks should be attributed into Foziling Group and Lu Zhenguan Group in Beihuaiyang metamorphic unit,respectively,and belong to Yangzi Craton. Combined with the previous analysis of faulted structure and the related ages investigation,the suture of Dabie Orogen between Yangzi and Huabei Cratons can be defined at Feizhong fault.
[石永红, 曹晟, 王娟,. 北淮阳变质单元岩石学、年代学分析及对大别造山带构造缝合线位置的探究[J]. 地质科学, 2014, 49(2):378-393.]
DOI:10.3969/j.issn.0563-5020.2014.02.004 Magsci URL
Up to now,the concreted location of the suture of Dabie Orogen is still ambiguous and more controversial. In this study,the bearing-graphite quartz schists and granitic gneisses have been inspected carefully across Fang Hushan(FHS)-Shu Cheng(SC) area in the most-north of Dabie Orogen. According to the analysis from petrology and geochronology,the conditions for the schists in the FHS are =300 ℃~450 ℃ and =0.2~0.7 GPa,and in the range of green-schist facies,while four groups of detrital zircons U-Pb ages for these schists have been distinguished: 1)2 465~1 522 Ma(5 grains); 2)1 140~938 Ma(14 grains); 3)804~646 Ma(4 grains); 4)460~422 Ma(14 grains). Other,zircon U-Pb ages from two granitic gneisses in the SC are 767.9±7.8 Ma and 770±16 Ma,respectively,and these gneisses have been formed in the range of 600 ℃~700 ℃ and 0.2~0.8 GPa. Hence,these two types of rocks should be attributed into Foziling Group and Lu Zhenguan Group in Beihuaiyang metamorphic unit,respectively,and belong to Yangzi Craton. Combined with the previous analysis of faulted structure and the related ages investigation,the suture of Dabie Orogen between Yangzi and Huabei Cratons can be defined at Feizhong fault.
[本文引用: 6]
[11]
Zhu Guang, Wang Yongsheng, Wang Wei, et al.An accreted micro-continent in the north of the Dabie Orogen, East China: Evidence from dating results of detrital zircons[J]. Tectonophysics, 2017, 698: 47-64.
[本文引用: 7]
[12]
Tang Jiafu, Hou Mingjin, Shi Qianhua, et al.The metamorphic strata sequence and structural deformation features, Beihuaiyang[J]. Geology of Anhui, 1995,(3):50-59.
URL
本文较详细阐述了近年来北淮阳地区在变质地层序列与构造变形特征方面研究的新进展。对梅山群的解体与新归属、原庐镇关群的解体与废名、佛子岭岩群的新含义作了简要论述。通过近年来不断深入的构造解剖,阐明了区内由早期伸展构造体制下的褶叠层;主期收缩体制下,以折劈理为标志的叠加向斜;以及晚期多期次自南而北的滑覆逆冲构造的主要特征,将为区内在新的地质背景下开展找矿工作提供了地质依据。
[汤加富, 侯明金, 石乾华,. 北淮阳地区变质地层序列与构造变形特征[J]. 安徽地质, 1995,(3):50-59.]
URL
本文较详细阐述了近年来北淮阳地区在变质地层序列与构造变形特征方面研究的新进展。对梅山群的解体与新归属、原庐镇关群的解体与废名、佛子岭岩群的新含义作了简要论述。通过近年来不断深入的构造解剖,阐明了区内由早期伸展构造体制下的褶叠层;主期收缩体制下,以折劈理为标志的叠加向斜;以及晚期多期次自南而北的滑覆逆冲构造的主要特征,将为区内在新的地质背景下开展找矿工作提供了地质依据。
[本文引用: 1]
[13]
Dong Shuwen, Oberhänsli R, Schmid R, et al.Occurrence of metastable rocks in deeply subducted continental crust from the Dabie Mountains, central China[J]. Episodes, 2002, 25(2): 84-89.
[14]
Oberhänsli R, Martinotti G, Schmid R, et al.Preservation of primary volcanic textures in the ultrahigh-pressure terrain of Dabie Shan[J]. Geology, 2002, 30(8): 699-702.
DOI:10.1130/0091-7613(2002)030<0699:POPVTI>2.0.CO;2 URL
Delicate primary volcanic features such as ash layers, volcaniclastic breccias, and pillow lavas with amygdaloidal rims have been identified in a terrigenous volcanosedimentary sequence forming part of the ultrahigh-pressure unit of the Dabie Shan, China. The presence of coesite relics in crosscutting dikes confirms an ultrahigh-pressure evolution for the entire sequence. Evaluation of the probable reaction history for zeolite compositions as supposed for the amygdaloidal rims reveals a scarcity of reactions at very high pressures. Such special conditions of low reactivity and fluid-conserving reactions, combined with a lack of directed stress, have allowed the remarkable preservation of these primary volcanic features despite deep subduction.
[15]
Gao Tianshan, Tang Jiafu, Sang Haiqing, et al.Whole-rock Ar-Ar dating for low-grade meta-volcanics within the Dabie orogen and its geological significance[J]. Chinese Science Bulletin, 2006, 51(12): 1 494-1 500.
URL
[高天山, 汤加富, 桑海清, . 大别山腹地浅变质岩层中富硅凝灰岩Ar-Ar年龄及其地质意义[J]. 科学通报, 2006, 51(10): 1 197-1 202.]
URL
[本文引用: 2]
[16]
Zhai Mingguo, Jiang Laili, Wang Qingchen, et al.A discussion on the relict of low-grade metamorphic rocks within ultrahigh pressure metamorphic belt in Dabieshan[J]. Chinese Science Bulletin, 2000, 45(2): 181-189.
DOI:10.3321/j.issn:0023-074X.1999.14.022 URL
一些作者提出在岳西县昌蒲镇的大别山超高压变质带内存在晚元古 代"浅变质岩片",其中还有柯石英榴辉岩火成岩脉侵入.因此对大别山的构造演化机制以及超高压变质作用理论提出重大质疑.据我们的研究,上述作者所报道 的"浅变质岩片"是一套强烈变形、细粒化和构造重结晶的糜棱岩,其原岩主要为超高压带内常见的区域花岗片麻岩以及榴辉岩和大理岩,还有少量也经历了强烈变 形的酸性和基性岩脉.它们的同位素年代学特征也与超高压变质岩带的特征一致.因此所谓的"浅变质岩片"是不存在的.
[翟明国, 江来利, 王清晨, . 关于在大别山超高压带内发现浅变质岩片的讨论[J]. 科学通报, 1999, 44(14): 1 560-1 568.]
DOI:10.3321/j.issn:0023-074X.1999.14.022 URL
一些作者提出在岳西县昌蒲镇的大别山超高压变质带内存在晚元古 代"浅变质岩片",其中还有柯石英榴辉岩火成岩脉侵入.因此对大别山的构造演化机制以及超高压变质作用理论提出重大质疑.据我们的研究,上述作者所报道 的"浅变质岩片"是一套强烈变形、细粒化和构造重结晶的糜棱岩,其原岩主要为超高压带内常见的区域花岗片麻岩以及榴辉岩和大理岩,还有少量也经历了强烈变 形的酸性和基性岩脉.它们的同位素年代学特征也与超高压变质岩带的特征一致.因此所谓的"浅变质岩片"是不存在的.
[本文引用: 1]
[17]
Dong Shuwen, Wang Xiaofeng, Huang Dezhi.Discovery of low grade metamorphic volcanic rock sheets within UHP in Dabie Mts. and its implications[J]. Chinese Science Bulletin, 1997, 42(14): 1 199-1 203.
DOI:10.1007/BF02029074 Magsci URL
正大别山中南部分布着约1000余平方公里的超高压变质(UHP)带,可谓世界出露规模最大的造山带超高压变质带.UHP岩石形成与折返机制成为大陆造山带研究热点.目前人们的工作焦点集中于UHP岩石的矿物、地球化学、年代学和变质作用(PTt轨迹),而UHP带内部岩石变形和组成研究相对较少,但已引起重视.作者自1992年在苏北赣榆UHP岩石之下发现“石桥浅变质岩构造窗”后,近年在大别山UHP带又找到了浅变质岩片,并进行露头填图、年代学及组成研究.本文现就其地质特征和年代学的初步成果进行讨论.1 浅变质岩片地质产状与特征作者发现的浅变质岩,位于岳西县菖蒲南4km港河桥(图1).菖蒲是大别山UHP带典型出露区,产出与大理岩的榴辉岩、片麻岩的榴辉岩,以及超基性岩的榴辉岩等不同类型的UHP岩石伴生.在其北约3km为大别山最大的榴辉岩体——碧溪岭岩体(约0.7km~2),这是与石榴橄榄岩伴生的UHP类型,浅变质岩片夹在榴辉岩-片麻岩和榴辉岩-大理岩中,出露宽约80m,长300m(未控制).岩性为酸性火山碎屑岩和火山沉积岩(板岩),变质程度低,由火山碎屑指示的原生层面依稀可辨,其SiO_2为68.46~72.04,Al_2O_3为18.52~21.56,K_2为O3.25~3.46,Na_2O为1.04~1.18;面理平行接触带,平行UHP带的面理产状,倾向南东(120°~140°/40°).接触带
[董树文, 王小凤, 黄德志. 大别山超高压变质带内浅变质岩片的发现及意义[J]. 科学通报, 1996, 41(9): 815-820.]
DOI:10.1007/BF02029074 Magsci URL
正大别山中南部分布着约1000余平方公里的超高压变质(UHP)带,可谓世界出露规模最大的造山带超高压变质带.UHP岩石形成与折返机制成为大陆造山带研究热点.目前人们的工作焦点集中于UHP岩石的矿物、地球化学、年代学和变质作用(PTt轨迹),而UHP带内部岩石变形和组成研究相对较少,但已引起重视.作者自1992年在苏北赣榆UHP岩石之下发现“石桥浅变质岩构造窗”后,近年在大别山UHP带又找到了浅变质岩片,并进行露头填图、年代学及组成研究.本文现就其地质特征和年代学的初步成果进行讨论.1 浅变质岩片地质产状与特征作者发现的浅变质岩,位于岳西县菖蒲南4km港河桥(图1).菖蒲是大别山UHP带典型出露区,产出与大理岩的榴辉岩、片麻岩的榴辉岩,以及超基性岩的榴辉岩等不同类型的UHP岩石伴生.在其北约3km为大别山最大的榴辉岩体——碧溪岭岩体(约0.7km~2),这是与石榴橄榄岩伴生的UHP类型,浅变质岩片夹在榴辉岩-片麻岩和榴辉岩-大理岩中,出露宽约80m,长300m(未控制).岩性为酸性火山碎屑岩和火山沉积岩(板岩),变质程度低,由火山碎屑指示的原生层面依稀可辨,其SiO_2为68.46~72.04,Al_2O_3为18.52~21.56,K_2为O3.25~3.46,Na_2O为1.04~1.18;面理平行接触带,平行UHP带的面理产状,倾向南东(120°~140°/40°).接触带
[本文引用: 1]
[18]
Schmid R, Romer R L, Franz L, et al.Basement-cover sequences within the UHP unit of the Dabie Shan[J]. Journal of metamorphic Geology, 2003, 21(6): 531-538.
DOI:10.1046/j.1525-1314.2003.00461.x URL
Field data define two lithologically distinct basement-cover sequences within the ultrahigh-pressure metamorphic (UHPM) unit of the Dabie Shan, eastern China. One of the cover units, the Changpu unit, comprises calc-arenitic metasediments in stratigraphic contact with a basement consisting of gneisses of the Yangtze craton. The second cover unit, the Ganghe unit, consists of felsic-intermediate metavolcanics and clastic metasediments. Basement exposure of the Ganghe unit is not known. Fold axes in the Ganghe unit are oblique to those of the Changpu unit, which are parallel to those of the Yangtze gneisses. Preservation of primary textures in some volcanic rocks, and tectonic separation from the Yangtze gneisses by a greenschist facies mylonite, support an interpretation of the Ganghe unit as a low-strain domain. Protolith associations in the Ganghe and Changpu units are compatible with deposition in a rift setting and along a passive continental margin, respectively. A U–Pb single zircon age of 761 ± 33 Ma for volcanoclastic rocks of the Ganghe unit demonstrates a Neoproterozoic deposition age, concordant with inferred rifting at that time. Eclogite facies parageneses in the gneisses and both cover units, along with P–T data demonstrate regional UHPM in the Dabie Shan.
[本文引用: 1]
[19]
Lin Wei, Wang Qingchen, Faure M, et al.Tectonic evolution of the Dabieshan orogen: In the view from polyphase deformation of the Beihuaiyang metamorphic zone[J]. Science in China (Series D), 2005, 48(7): 886-899.
URL
[林伟, 王清晨, Faure M, . 从北淮阳构造带的多期变形透视大别山构造演化[J]. 中国科学:D辑, 2005, 35(2): 127-139.]
URL
[本文引用: 3]
[20]
Wu Yuanbao, Zheng Yongfei, Gong Bing, et al.Zircon U-Pb ages and oxygen isotope compositions of the Luzhenguan magmatic complex in the Beihuaiyang zone[J]. Acta Petrologica Sinica, 2004, 20(5):1 007-1 024.
[吴元保, 郑永飞, 龚冰, . 北淮阳庐镇关岩浆岩锆石U-Pb年龄和氧同位素组成[J].岩石学报, 20(5): 1 007-1 024.]
[本文引用: 1]
[21]
Jiang Laili, Wolfgang S, Chen Fukun, et al.U-Pb zircon ages for the Luzhenguan complex in northern part of the eastern Dabie orogen[J]. Science in China (Series D), 2005, 48(9): 1 357-1 367.
[江来利, Wolfgang S, 陈福坤, 等. 大别造山带北部卢镇关杂岩的U-Pb锆石年龄[J]. 中国科学:D辑, 2005, 35(5): 411-419.]
[22]
Liu Jingbo, Zhang Lingmin, Ye Kai, et al.Oxygen isotopes of whole-rock and zircon and zircon U-Pb ages of meta-rhvolite from the Luzhenguan Group and associated meta-granite in the northern Dabie Mountains[J]. Acta Petrologica Sinica, 2013, 29(5): 1 511-1 524.
URL
[刘景波, 张灵敏, 叶凯, . 大别山北部卢镇关群变质火山岩和共生变质的花岗岩全岩和锆石氧同位素、锆石U-Pb年代学研究[J]. 岩石学报, 2013, 29(5): 1 511-1 524.]
URL
[本文引用: 1]
[23]
Hacker B R, Ratschbacher L, Webb L, et al.U/Pb zircon ages constrain the architecture of the ultrahigh-pressure Qinling-Dabie Orogen, China[J]. Earth and Planetary Science Letters, 1998, 161(1/4): 215-230.
[本文引用: 2]
[24]
Liu Yican, Li Shuguang, Xu Shutong.Zircon SHRIMP U-Pb dating for gneisses in northern Dabie high T/P metamorphic zone, central China: Implications for decoupling within subducted continental crust[J]. Lithos, 2007, 96(1/2): 170-185.
[本文引用: 2]
[25]
Malaspina N, Hermann J, Scambelluri M, et al.Multistage metasomatism in ultrahigh-pressure mafic rocks from the North Dabie Complex (China)[J]. Lithos, 2006, 90(1): 19-42.
DOI:10.1016/j.lithos.2006.01.002 URL
Release of metamorphic fluids within the slab and/or from the slab to the mantle wedge in subduction environments can produce important metasomatic effects. Ultrahigh-pressure (UHP) metasomatised rocks represent ideal materials to study the element exchange at pressures corresponding to sub-arc depths in subduction zones. We present a petrologic and geochemical study of eclogites (s.l.) from the Dabie Mountains (China). The investigated samples were collected in the North Dabie Complex, where eclogite-facies rocks are significantly overprinted by granulite-facies metamorphism and partial melting. The studied eclogites are included in meta-lherzolitic bodies, which are in turn hosted by leucocratic gneisses. The textural relations among the various rock-forming minerals enabled us to identify several re-crystallisation stages. The peak (UHP) paragenesis consists of garnet, clinopyroxene and rutile. UHP garnet and clinopyroxene display oriented inclusions of polycrystalline rods of rutile + ilmenite and of albite, K–Ba-feldspar and quartz, respectively. Garnet and clinopyroxene are both rimmed by an inclusion free zone that formed after the peak, still at high-pressure conditions. Such optical zoning does not correspond to a difference in major element concentrations between garnet core and rim. This observation provides evidence that the major element composition of garnet was reset during exhumation, thus preventing thermobarometric determination of peak metamorphic conditions. Further decompression is documented by the formation of limited ilmenite + amphibole and granulite-facies coronas consisting of clinopyroxene, orthopyroxene, plagioclase and amphibole around garnet. In order to investigate the stability of observed mineral parageneses, a series of reconnaissance piston cylinder synthesis experiments were carried out in an identical bulk composition. The experimental study indicates that the peak metamorphic paragenesis is stable at P653.5 GPa and T ≥ 750–800 °C. The petrological study, combined with bulk-rock and mineral trace element analyses, provides evidence of intense metasomatism affecting these eclogites. The bulk-rock major and trace element compositions indicate that the eclogites derive from basaltic protoliths with MORB and E-MORB affinity. Compared with such basalts, the studied rocks show strong depletion in SiO 2 and alkalis and enrichment in MgO and FeO. These features likely derive from element exchange with ultramafic rocks prior to subduction, possibly related with the influx of Si-depleted and Mg-enriched fluids produced during the serpentinisation of the associated lherzolitic rocks. On the other hand, the trace element bulk-rock compositions show strong enrichment in Cs, Ba and Pb. The same characteristic enrichment and fractionation is recorded by peak metamorphic clinopyroxene but not in retrograde amphibole. Therefore, influx of crustal fluids transporting LILE and light elements must have occurred during subduction at UHP conditions. This stage likely records the tectonic coupling of the mafic–ultramafic rocks with the associated crustal rock units and provides evidence of LILE mobility between different slab components.
[本文引用: 1]
[26]
Suo Shutian, Zhong Zengqiu, Zhou Hanwen, et al.Massive eclogites and their tectonic significance in Dabie-Sulu UHP metamorphic belt, east-central China[J]. Earth Science, 2003, 28(2): 111-120.
DOI:10.3321/j.issn:1000-2383.2003.02.001 URL
大别-苏鲁超高压(>27×108Pa)变质带内的榴辉岩,在大陆深俯冲、碰撞和折返剥露过程中,大都遭受了强烈的变形和变质作用的重置与再造.但是,大型榴辉岩体核部以及包裹于大理岩和石榴橄榄岩体内部的块状榴辉岩,往往保留其初始简单的矿物组合、中-细粒状变晶结构和块状构造.详细地分析了块状榴辉岩的几何学、岩相学及变质作用特征,指出它们是超高压榴辉岩递进及多期变质变形分解作用的残留体,位于尺度不同的弱应变域内,是大陆深俯冲及碰撞作用的真正记录.
[索书田, 钟增球, 周汉文,. 大别—苏鲁超高压变质带内的块状榴辉岩及其构造意义[J]. 地球科学, 2003, 28(2): 111-120.]
DOI:10.3321/j.issn:1000-2383.2003.02.001 URL
大别-苏鲁超高压(>27×108Pa)变质带内的榴辉岩,在大陆深俯冲、碰撞和折返剥露过程中,大都遭受了强烈的变形和变质作用的重置与再造.但是,大型榴辉岩体核部以及包裹于大理岩和石榴橄榄岩体内部的块状榴辉岩,往往保留其初始简单的矿物组合、中-细粒状变晶结构和块状构造.详细地分析了块状榴辉岩的几何学、岩相学及变质作用特征,指出它们是超高压榴辉岩递进及多期变质变形分解作用的残留体,位于尺度不同的弱应变域内,是大陆深俯冲及碰撞作用的真正记录.
[本文引用: 1]
[27]
Lin Wei, Enami M, Faure M, et al.Survival of eclogite xenolith in a Cretaceous granite intruding the Central Dabieshan migmatite gneiss dome (Eastern China) and its tectonic implications[J]. International Journal of Earth Sciences, 2007, 96(4): 707-724.
DOI:10.1007/s00531-006-0129-z Magsci
<a name="Abs1"></a>Investigation of an eclogite xenolith, discovered in a Cretaceous granite from the Central Domain of the Dabieshan massif in eastern China, yields new petrological insights into the high to ultrahigh-pressure metamorphism, experienced by the Qinling-Dabie orogen. Prior to inclusion as a xenolith in the granite during the Early Cretaceous, this eclogite xenolith had recorded a complex metamorphic evolution that complies with subduction and exhumation processes experienced by the continental crust of the South China Block. Well-preserved mineral parageneses substantiate the prograde and retrograde stages revealed by inclusions in porphyroblastic garnet and zoned minerals such as garnet, omphacite and amphibole in the matrix. The relatively low P/T re-equilibration during a late metamorphic stage was textually inferred by the presence of aluminous and calcic-subcalcic amphiboles such as katophorite, edenite, taramite and pargasite as main matrix phases. According to our U/Pb, Rb/Sr and new <sup>40</sup>Ar/<sup>39</sup>Ar geochronological results, namely109&nbsp;±&nbsp;1 and 112&nbsp;±&nbsp;2&nbsp;Ma plateau ages for muscovite and amphiboles, respectively, two successive but distinct cooling stages account for the thermal history of the granite&#8211;migmatite gneiss dome that forms the Central Dabieshan Domain. We argue that prior to the Cretaceous doming, the Central Dabieshan Domain experienced a tectono-metamorphic evolution similar to that observed in the high-pressure to ultra high-pressure units developed in the Southern Dabieshan Domain and Hong&#8217;an massif.
[本文引用: 1]
[28]
Ratschbacher L, Hacker B R, Webb L E, et al.Exhumation of the ultrahigh-pressure continental crust in east central China: Cretaceous and Cenozoic unroofing and the Tan-Lu fault zone[J]. Journal of Geophysical Research, 2000, 105(B6): 13 303-13 338.
[本文引用: 3]
[29]
Wu Yuanbao, Zheng Yongfei, Zhang Shaobing, et al.Zircon U-Pb ages and Hf isotope compositions of migmatite from the North Dabie terrane in China: Constraints on partial melting[J]. Journal of Metamorphic Geology, 2007, 25(9): 991-1 009.
[本文引用: 1]
[30]
Wang Yongsheng, Xiang Biwei, Zhu Guang, et al.Structural and geochronological evidence for Early Cretaceous orogen-parallel extension of the ductile lithosphere in northern Dabie orogenic belt, east China[J]. Journal of Structural Geology, 2011, 33(3): 362-380.
DOI:10.1016/j.jsg.2010.09.002 Magsci
The WNW-trending North Dabie dome (NDD) in the northern Dabie orogenic belt is bounded by the Xiaotian-Mozitan ductile shear zone (XMSZ) in the north and the Wuhe-Shuihou shear zone (WSSZ) in the south. Fabric geometries and kinematics of both the XMSZ and the WSSZ are similar. They both show a top-to-NW or WNW sense of shear and display similar microstructures which indicate that the deformation temperature was about 600-650 degrees C. (40)Ar-(39)Ar dating of hornblende and biotite from the mylonites of the XMSZ suggests that the shear zone was developed prior to 142 Ma. U-Pb zircon LA-ICPMS dating of undeformed granite dikes that cut the XMSZ suggests that the ductile shearing occurred before 130 Ma. The WSSZ was also developed in the Early Cretaceous. The interior of the NDD is dominated by top-to-NW or WNW sense of shear in the migmatitic gneiss and deformed plutons of the earliest Early Cretaceous ages. We suggest that the XMSZ, the WSSZ, and the interior of the NDD were involved in the same Early Cretaceous deformation. The XMSZ and the WSSZ were originally a single connected, more flat-lying zone, which we call the East Dabie Detachment Zone (EDDZ). It developed at a crustal level of over 18 km in depth. Kinematics of the EDDZ suggest that the ductile crust and possibly part of the lithospheric mantle in the eastern Dabie orogen underwent pervasive orogen-parallel and ESE-ward extension at the beginning of the Early Cretaceous. Large-scale magmatic intrusions following this deformation and the resultant increase in buoyancy led to the exhumation of the NDD and the warping of the EDDZ. Erosion separated the EDDZ into two zones (the XMSZ and the WSSZ) as observed today. Many metamorphic core complexes of Early Cretaceous were developed in the eastern North China Craton, most showing top-to-NW or WNW sense of shear. We suggest that such a widespread uniform shear sense reflects a uniform flow direction of the ductile lithosphere in the East China that has also been documented in the Liaonan, Yiwulushan and Yumenshan metamorphic core complexes in the northeastern part of the North China Craton. (C) 2010 Elsevier Ltd. All rights reserved.
[本文引用: 1]
[31]
Hirth G, Tullis J.Dislocation creep regimes in quartz aggregates[J]. Journal of Structural Geology, 1992, 14(2): 145-159.
DOI:10.1016/0191-8141(92)90053-Y URL
Using optical and TEM microscopy we have determined that three regimes of dislocation creep occur in experimentally deformed quartz aggregates, depending on the relative rates of grain boundary migration, dislocation climb and dislocation production. Within each regime a distinctive microstructure is produced due primarily to the operation of different mechanisms of dynamic recrystallization. At lower temperatures and faster strain rates the rate of dislocation production is too great for diffusion-controlled dislocation climb to be an effective recovery mechanism. In this regime recovery is accommodated by strain-induced grain boundary migration recrystallization. With an increase in temperature or decrease in strain rate, the rate of dislocation climb becomes sufficiently rapid to accommodate recovery. In this regime dynamic recrystallization occurs by progressive subgrain rotation. With a further increase in temperature or decrease in strain rate dislocation climb remains sufficiently rapid to accommodate recovery. However, in this regime grain boundary migration is rapid, thus recrystallization occurs by both grain boundary migration and progressive subgrain rotation. The identification of the three regimes of dislocation creep may have important implications for the determination of flow law parameters and the calibration of recrystallized grain size piezometers. In addition, the identification of a particular dislocation creep regime could be useful in helping to constrain the conditions at which a given natural deformation has occurred.
[本文引用: 1]
[32]
Stipp M, Stünitz H, Heilbronner R, et al.The eastern Tonale fault zone: A ‘natural laboratory’ for crystal plastic deformation of quartz over a temperature range from 250 to 700 ℃[J]. Journal of Structural Geology, 2002, 24(12): 1 861-1 884.
[本文引用: 1]
[33]
Yan Jun, Liu Jianmin, Li Quanzhong, et al.In situ zircon Hf-O isotopic analyses of late Mesozoic magmatic rocks in the lower Yangtze River belt, central eastern China: Implications for petrogenesis and geodynamic evolution[J]. Lithos, 2015, 227: 57-76.
[本文引用: 1]
[34]
Ludwig K R.User's Manual for Isoplot 3.14: A Geochronological Toolkit for Microsoft Excel[M]. California: Berkeley Geochronology Center Special Publication, 2004.
[本文引用: 1]
[35]
Belousova E A, Griffin W L, O'Reilly S Y,et al. Igneous zircon: Trace element composition as an indicator of source rock type[J]. Contributions to Mineralogy and Petrology, 2002, 143(5): 602-622.
[本文引用: 1]
[36]
Fedo C M,Sircombe K N, Rainbird R H.Detrital zircon analysis of the sedimentary record[J]. Reviews in Mineralogy and Geochemistry, 2003, 53(1): 277-303.
DOI:10.2113/0530277 URL
The composition of “heavy,” or accessory, detrital minerals in sediments and sedimentary rocks has been a topic of quantitative study for at least the last seventy years, beginning with the first issue of the Journal of Sedimentary Petrology in May 1931 (Tyler 1931, Pentland 1931). Zircon has since played a prominent and complex role in interpreting the composition and history of modern and ancient sediments. Because zircon is highly refractory at Earth’s surface, it occurs in virtually all sedimentary deposits and so provides a critical link in understanding the source history of a deposit. Twenhofel (1941), in a pioneering paper on the frontiers of sedimentary mineralogy and petrology, noted that the simple presence of detrital zircon would be of little value in determining its source: “Zircons from a half dozen sources with as many different properties may be present in a sediment and merely be identified as zircon. Parent rocks cannot be positively identified on such data. The variety or varieties must be identified and their optical properties determined.” From very early on, then, it was recognized that detrital zircon would be a powerful tool in understanding provenance, and thus, sedimentary dispersal systems. Interpretive goals matured considerably in the subsequent decades, especially with major advances in microscopy, mineral chemistry, isotope tracer geochemistry, and geochronology, each addressing different aspects of provenance, sedimentation, and Earth history. The hundreds of published studies utilizing detrital zircon in the last 20 years indicate the increasing success in assessing provenance, paleogeography, and tectonic reconstructions. Selected studies are highlighted in this review to illustrate ways in which detrital zircon can be used for interpreting the stratigraphic record, and thus, the past surface conditions of Earth. In it we will outline the quantitative techniques involved in the sampling protocol and interpretation of data and then …
[本文引用: 2]
[37]
Cawood P A, Nemchin A A, Strachan R.Provenance record of Laurentian passive-margin strata in the northern Caledonides: Implications for paleodrainage and paleogeography[J]. Geological Society of America Bulletin, 2007, 119(7): 993-1 003.
[本文引用: 1]
[38]
Dong Yunpeng, Liu Xiaoming, Neubauer F, et al.Timing of Paleozoic amalgamation between the North China and South China blocks: Evidence from detrital zircon U-Pb ages[J]. Tectonophysics, 2013, 586(2): 173-191.
[本文引用: 1]
[39]
Jin Ke, Xu Wenliang, Wang Qinghai, et al.Formation time and sources of the Huaiguang "Migmatic Granodiorite" in Bengbu, Anhui Province: Evidence from SHRIMP Zircon U-Pb geochronology[J]. Acta Geosicientia Sinica, 2003, 24(4): 331-335.
DOI:10.3321/j.issn:1006-3021.2003.04.007 URL
对蚌埠淮光花岗闪长岩的岩相学和锆石阴极发光图象研究表明,淮光“混合花岗闪长岩”为岩浆结晶作用的产物,岩石形成后受到了应力作用的改造。锆石SHRIMP U—Pb定年结果和岩浆锆石的SHRIMP U-Pb年龄显示淮光花岗闪长岩形成于130.0±2.0 Ma;大多数继承锆石的年龄集中在1 800~1 900 Ma、2 300~2 517 Ma和3 443 Ma,这意味着淮光花岗闪长岩的母岩浆起源于华北地块基底的部分熔融。早白垩世(130 Ma左右)的岩浆作用是引起继承锆石和碎屑锆石Pb丢失的重要原因,同时也是华北地块东部岩石圈减薄的最重要时期。130 Ma左右的岩浆作用和岩石圈减薄应与太平洋板块的俯冲相联系。
[靳克, 许文良, 王清海, . 蚌埠淮光“混合花岗闪长岩”的形成时代及源区: 锆石SHRIMP U-Pb地质年代学证据[J]. 地球学报, 2003, 24(4): 331-335.]
DOI:10.3321/j.issn:1006-3021.2003.04.007 URL
对蚌埠淮光花岗闪长岩的岩相学和锆石阴极发光图象研究表明,淮光“混合花岗闪长岩”为岩浆结晶作用的产物,岩石形成后受到了应力作用的改造。锆石SHRIMP U—Pb定年结果和岩浆锆石的SHRIMP U-Pb年龄显示淮光花岗闪长岩形成于130.0±2.0 Ma;大多数继承锆石的年龄集中在1 800~1 900 Ma、2 300~2 517 Ma和3 443 Ma,这意味着淮光花岗闪长岩的母岩浆起源于华北地块基底的部分熔融。早白垩世(130 Ma左右)的岩浆作用是引起继承锆石和碎屑锆石Pb丢失的重要原因,同时也是华北地块东部岩石圈减薄的最重要时期。130 Ma左右的岩浆作用和岩石圈减薄应与太平洋板块的俯冲相联系。
[本文引用: 1]
[40]
Xu Lijuan, Xiao Yilin, Wu Fei, et al.Anatomy of garnets in a Jurassic granite from the south-eastern margin of the North China Craton: Magma sources and tectonic implications[J]. Journal of Asian Earth Science, 2013, 78: 198-221.
[本文引用: 1]
[41]
Xu Wenliang, Yang Debin, Pei Fuping, et al.Age of the Wuhe complex in the Bengbu uplift: Evidence from LA-ICP-MS zircon U-Pb dating[J]. Geology in China, 2006, 33(1):132-137.
DOI:10.3969/j.issn.1000-3657.2006.01.014 URL
Abstract:This paper reports the LA-ICP-MS zircon U-Pb dating results of garnet-plagioclase pyroxenite in the Wuhe complex in the Bengbu uplift. The cathodoluminescence (CL) images of zircons from the garnet-plagioclase pyroxenite show three textural types of zircon, i. e.:euhedral zircon of homogeneous absorption, zircons with a distinct internal structure and typical core-rim structure and euhedral zircons with typical growth zones. The zircon U-Pb dating of spots with different intensities of zircon absorption indicates that their 207Pb/206Pb ages range from 1783±8 to 1895±8 Ma and that the weighted mean age of 49 analyzed spots is 1833±8Ma. This result suggests that the Wuhe complex was formed in the Paleoproterozoic, which is in agreement with the age of formation of the central orogenic belt of the North China craton and the age of high-pressure granulite-facies metamorphism in Jiaodong, and further implies that the Wuhe complex should belong to the basement of the North China craton.
[许文良, 杨德彬, 裴福萍, . 蚌埠隆起区五河杂岩的形成时代: 锆石LA-ICP-MS U-Pb定年证据[J]. 中国地质, 2006, 33(1): 132-137.]
DOI:10.3969/j.issn.1000-3657.2006.01.014 URL
Abstract:This paper reports the LA-ICP-MS zircon U-Pb dating results of garnet-plagioclase pyroxenite in the Wuhe complex in the Bengbu uplift. The cathodoluminescence (CL) images of zircons from the garnet-plagioclase pyroxenite show three textural types of zircon, i. e.:euhedral zircon of homogeneous absorption, zircons with a distinct internal structure and typical core-rim structure and euhedral zircons with typical growth zones. The zircon U-Pb dating of spots with different intensities of zircon absorption indicates that their 207Pb/206Pb ages range from 1783±8 to 1895±8 Ma and that the weighted mean age of 49 analyzed spots is 1833±8Ma. This result suggests that the Wuhe complex was formed in the Paleoproterozoic, which is in agreement with the age of formation of the central orogenic belt of the North China craton and the age of high-pressure granulite-facies metamorphism in Jiaodong, and further implies that the Wuhe complex should belong to the basement of the North China craton.
[本文引用: 1]
[42]
Guo Sushu, Li Shuguang.SHRIMP zircon U-Pb ages for the Paleoproterozoic metamorphic-magmatic events in the southeast margin of the North China Craton[J]. Science in China (Series D), 2009, 52(8): 1 039-1 045.
URL
用锆石SHRIMP U—Pb法测定了徐宿地区中生代岩浆岩携带的深源石榴辉石角闪岩包体的变质年龄为(1918±56)Ma,蚌埠隆起区五河群大理岩层所夹的榴闪岩透镜体变质年龄为(1857±19)Ma,蚌埠隆起东端石门山变形花岗岩的岩浆结晶年龄为(2054±22)Ma.徐宿地区和蚌埠隆起都位于华北克拉通东南缘,因此这些年代学结果指出华北陆块东南缘也存在一古元古代活动带,它的变质和岩浆事件发生时代与华北克拉通其他3个古元古代活动带一致.考虑到郯庐断裂带中生代曾发生过大规模的左行走滑,将胶东地区(胶-辽-吉古元古代活动带的南段)恢复到断裂带活动以前的位置,恰可与徐宿-蚌埠地区对应,说明徐宿-蚌埠古元古代活动带很可能是胶-辽-吉古元古代活动带的西南延伸.
[郭素淑, 李曙光. 华北克拉通东南缘古元古代变质和岩浆事件的锆石SHRIMP U-Pb年龄[J]. 中国科学:D辑, 2009, 39(6): 694-699.]
URL
用锆石SHRIMP U—Pb法测定了徐宿地区中生代岩浆岩携带的深源石榴辉石角闪岩包体的变质年龄为(1918±56)Ma,蚌埠隆起区五河群大理岩层所夹的榴闪岩透镜体变质年龄为(1857±19)Ma,蚌埠隆起东端石门山变形花岗岩的岩浆结晶年龄为(2054±22)Ma.徐宿地区和蚌埠隆起都位于华北克拉通东南缘,因此这些年代学结果指出华北陆块东南缘也存在一古元古代活动带,它的变质和岩浆事件发生时代与华北克拉通其他3个古元古代活动带一致.考虑到郯庐断裂带中生代曾发生过大规模的左行走滑,将胶东地区(胶-辽-吉古元古代活动带的南段)恢复到断裂带活动以前的位置,恰可与徐宿-蚌埠地区对应,说明徐宿-蚌埠古元古代活动带很可能是胶-辽-吉古元古代活动带的西南延伸.
[本文引用: 1]
[43]
Yang Debin, Xu Wenliang, Pei Fuping, et al.Petrogenesis of the Paleoproterozoic K-Feldspar Granites in Bengbu Uplift:Constraints from Petro-Geochemistry,Zircon U-Pb Dating and Hf Isotope[J]. Earth Science, 2009, 34(1):148-164.
DOI:10.3321/j.issn:1000-2383.2009.01.014 URL
对蚌埠隆起区庄子里和磨盘山钾长花岗岩进行了系统的年代学和地球化学以及锆石Hf同位素的研究,以便对其岩石成因进行约束.研究结果表明,庄子里和磨盘山钾长花岗岩中锆石发育震荡生长环带,且具有较高的Th/U比值(0.13~1.47),反映了岩浆成因特征.对庄子里和磨盘山钾长花岗岩中岩浆锆石进行的LA-ICP-MSU-Pb定年结果(上交点年龄)分别为2104±20Ma和2196±190Ma,这表明蚌埠隆起区钾长花岗岩的形成时代为古元古代.钾长花岗岩的SiO2和K2O含量分别介于69.65%~77.95%和4.98%~5.17%之间;该类岩石富集轻稀土元素和Zr、Hf、Rb、Th、U等元素,明显亏损Ba、Sr、Eu、P和Ti等元素;它们的εNd(t)值变化于-3.4~+3.2之间,Nd的模式年龄变化于2.31~2.79Ga之间;钾长花岗岩中锆石的εHf(t)值和Hf同位素两阶段模式年龄分别介于-5.1~+7.8和2.26~2.83Ga之间.上述特征表明,蚌埠隆起区钾长花岗岩的原始岩浆起源于有少量古老地壳物质涉入的新生下地壳的部分熔融.庄子里和磨盘山钾长花岗岩为A型花岗岩,形成于伸展的构造背景.
[杨德彬, 许文良, 裴福萍, . 蚌埠隆起区古元古代钾长花岗岩的成因: 岩石地球化学、锆石U-Pb年代学与Hf 同位素的制约[J]. 地球科学, 2009, 34(1): 148-164.]
DOI:10.3321/j.issn:1000-2383.2009.01.014 URL
对蚌埠隆起区庄子里和磨盘山钾长花岗岩进行了系统的年代学和地球化学以及锆石Hf同位素的研究,以便对其岩石成因进行约束.研究结果表明,庄子里和磨盘山钾长花岗岩中锆石发育震荡生长环带,且具有较高的Th/U比值(0.13~1.47),反映了岩浆成因特征.对庄子里和磨盘山钾长花岗岩中岩浆锆石进行的LA-ICP-MSU-Pb定年结果(上交点年龄)分别为2104±20Ma和2196±190Ma,这表明蚌埠隆起区钾长花岗岩的形成时代为古元古代.钾长花岗岩的SiO2和K2O含量分别介于69.65%~77.95%和4.98%~5.17%之间;该类岩石富集轻稀土元素和Zr、Hf、Rb、Th、U等元素,明显亏损Ba、Sr、Eu、P和Ti等元素;它们的εNd(t)值变化于-3.4~+3.2之间,Nd的模式年龄变化于2.31~2.79Ga之间;钾长花岗岩中锆石的εHf(t)值和Hf同位素两阶段模式年龄分别介于-5.1~+7.8和2.26~2.83Ga之间.上述特征表明,蚌埠隆起区钾长花岗岩的原始岩浆起源于有少量古老地壳物质涉入的新生下地壳的部分熔融.庄子里和磨盘山钾长花岗岩为A型花岗岩,形成于伸展的构造背景.
[本文引用: 1]
[44]
Liu Sheng'ao, Li Shuguang, Guo Sushu, et al. The Cretaceous adakitic-basaltic-granitic magma sequence on south-eastern margin of the North China Craton: Implications for lithospheric thinning mechanism[J]. Lithos. , 2012, 134/135: 163-178.
[本文引用: 1]
[45]
Nie Feng, Shi Yonghong, Zhang Zhongbao, et al.The initial time of the Tan-Lu wrench fault: In the view of geochronological data of the basement rocks, northern Anhui Province[J]. Chinese Science Bulletin, 2015, 60(24): 2 315-2 326.
URL
[聂峰, 石永红, 张忠宝, . 安徽北部郯庐断裂两侧基底岩石年龄及对郯庐断裂初始开启时间的限定[J]. 科学通报, 2015, 60(24): 2 315-2 326.]
URL
[本文引用: 1]
[46]
Nie Feng, Zhang Zhongbao, Shi Yonghong, et al.Comparison study of typical rocks separated from Feidong Group and Huoqiu Group in the Tan-Lu Fault zone (Anhui segment)[J]. Acta Petrologica Sinica, 2016, 32(4): 1 087-1 100.
URL
郯庐断裂带(安徽段)内部物质组成十分复杂,现有研究认为郯庐内部以扬子板块为主体,对于是否存在西侧华北板块物质混入尚不清楚.为此本文选取了3个特征性样品展开了细致的岩相学研究、温压估算以及锆石U-Pb定年分析,分别为:霍邱群样品WS069-1(磁铁石榴角闪岩)以及样品WS070-1(石榴黑云母片岩);肥东群样品TF003-1(石榴黑云母片岩).研究发现,霍邱群磁铁石榴角闪岩与肥东群磁铁石榴角闪岩的矿物组合及矿物主量元素特征基本一致.针对霍邱群石榴黑云母片岩与肥东群石榴黑云母片岩的峰期变质条件评价也相互匹配.本文在霍邱群仅发现了~3.2Ga、3.0Ga、2.80Ga、2.74Ga等四组反映源区结晶时代的碎屑锆石年龄,但结合前人对霍邱群和五河群的研究可以认为霍邱群的峰期变质年龄应为2.44Ga,这与肥东群磁铁石榴角闪岩和石榴黑云母片岩的峰期变质年龄2.47~2.41Ga吻合.因此肥东群和霍邱群相同特征性岩石磁铁石榴角闪岩从岩相学、变质P-T条件及变质时代等方面皆具可比性,从而推测肥东群磁铁石榴角闪岩和石榴黑云母片岩构造透镜体应为因郯庐断裂左旋走滑作用而卷入肥东群中的霍邱群岩片.
[聂峰, 张忠宝, 石永红, .郯庐断裂(安徽段)两侧肥东群与霍邱群特征性岩石对比研究[J]. 岩石学报, 2016, 32(4): 1 087-1 100.]
URL
郯庐断裂带(安徽段)内部物质组成十分复杂,现有研究认为郯庐内部以扬子板块为主体,对于是否存在西侧华北板块物质混入尚不清楚.为此本文选取了3个特征性样品展开了细致的岩相学研究、温压估算以及锆石U-Pb定年分析,分别为:霍邱群样品WS069-1(磁铁石榴角闪岩)以及样品WS070-1(石榴黑云母片岩);肥东群样品TF003-1(石榴黑云母片岩).研究发现,霍邱群磁铁石榴角闪岩与肥东群磁铁石榴角闪岩的矿物组合及矿物主量元素特征基本一致.针对霍邱群石榴黑云母片岩与肥东群石榴黑云母片岩的峰期变质条件评价也相互匹配.本文在霍邱群仅发现了~3.2Ga、3.0Ga、2.80Ga、2.74Ga等四组反映源区结晶时代的碎屑锆石年龄,但结合前人对霍邱群和五河群的研究可以认为霍邱群的峰期变质年龄应为2.44Ga,这与肥东群磁铁石榴角闪岩和石榴黑云母片岩的峰期变质年龄2.47~2.41Ga吻合.因此肥东群和霍邱群相同特征性岩石磁铁石榴角闪岩从岩相学、变质P-T条件及变质时代等方面皆具可比性,从而推测肥东群磁铁石榴角闪岩和石榴黑云母片岩构造透镜体应为因郯庐断裂左旋走滑作用而卷入肥东群中的霍邱群岩片.
[本文引用: 1]
[47]
Yin Chongyu, Liu Dunyi, Gao Linzhi, et al.Lower boundary age of the Nanhua System and the Gucheng glacial stage: Evidence from SHRIMP II dating[J]. Chinese Science Bulletin, 2003, 48(16): 1 657-1 662.
[本文引用: 1]
[48]
Zhang Shaobing, Zheng Yongfei, Wu Yuanbao, et al.Zircon U-Pb age and Hf isotope evidence for 3.8 Ga crustal remnant and episodic reworking of Archean crust in South China[J]. Earth and Planetary Science Letters, 2006, 252(1/2): 56-71.
[本文引用: 1]
[49]
Zhang Shaobing, He Qiang, Zheng Yongfei.Geochronological and geochemical evidence for the nature of the Dongling Complex in South China[J]. Precambrian Research, 2015, 256: 17-30.
DOI:10.1016/j.precamres.2014.10.013 URL
The ancient basement of the Yangtze craton in South China is poorly exposed and its early evolution is loosely constrained yet. The Dongling Complex is usually advocated as the ancient basement of the Yangtze craton without an intensive study yet. Schist and gneiss from the Dongling Complex have high SiO2 and Al2O3 contents, low CIA values. Their REE and trace element distribution patterns are similar to PAAS and average upper crust. Their δ18O values are generally higher than 10‰ for quartz, demonstrating a sedimentary origin for their protolith. Detrital zircon U–Pb dating yields three distinct age populations for the Dongling metasediments: (1) >2.4Ga with negative 07Hf(t) values, mostly on cores and unzoned grains; (2) 652.0Ga with negative 07Hf(t) values on weak luminance and unzoned domains; (3) 730–830Ma with 07Hf(t) values ranging from 6124.8 to 4.9 on oscillatory zonings and fragmented euhedral grains. The zircons of different U–Pb ages exhibit similar REE patterns but different Ti-in-zircon temperatures. The zircon age populations are consistent with provenances from both the Yangtze craton and the Jiangnan orogen for the Dongling sediments. The youngest detrital zircon age of 731±13Ma provides an upper limit for the deposition age; the geological occurrence of overlying strata provides a lower limit of 635Ma for the deposition age. In view of the extensional setting in South China during the middle Neoproterozoic, the most plausible tectonic environment for deposition of the Dongling sediments is a failed continental rift basin between the Yangtze craton and the Jiangnan orogen. Therefore, the Dongling Complex is not the ancient basement of the Yangtze craton despite the involvement of some basement materials in its protolith.
[本文引用: 1]
[50]
Wang Wei, Chen Fukun, Hu Rong, et al.Provenance and tectonic setting of Neoproterozoic sedimentary sequences in the South China Block: Evidence from detrital zircon ages and Hf-Nd isotopes[J]. International Journal of Earth Sciences, 2012, 101(7): 1 723-1 744.
[本文引用: 1]
[51]
Wang Lijuan, Yu Jinhai, Griffin W L,et al. Early crustal evolution in the western Yangtze Block: Evidence from U-Pb. Early crustal evolution in the western Yangtze Block: Evidence from U-Pb and Lu-Hf isotopes on detrital zircons from sedimentary rocks[J]. Precambrian Research, 2012, 222/223: 368-385.
[本文引用: 1]
[52]
Wang Lijuan, Griffin W L, Yu Jinhai, et al.U-Pb and Lu-Hf isotopes in detrital zircon from Neoproterozoic sedimentary rocks in the northern Yangtze Block: Implications for Precambrian crustal evolution[J]. Gondwana Research, 2013, 23(4): 1 261-1 272.
[本文引用: 1]
[53]
Liu Xiaoming, Gao Shan, Diwu Chunrong, et al.Precambrian crustal growth of Yangtze Craton as revealed by detrital zircon studies[J]. American Journal of Science, 2008, 308(4): 421-468.
[本文引用: 1]
[54]
Du Qiuding, Wang Zhengjiang, Wang Jian, et al.LA-ICP-MS U-Pb ages of detrital zircons from the Neoproterozoic Chang'an Formation in central Hunan and its geological implications[J]. Geological Review, 2013, 59(2):334-344.
DOI:10.3969/j.issn.0371-5736.2013.02.015 URL
The Yangtze Block in South China is one of the important regions in the world where the Neoproterozoic glacial sediments are well developed and well studied. In this paper, we report and analyse the LA-ICP-MS U-Pb ages of detrital Zircon grains from the Jiangkou Group in the Central Hunan, Southeastern Yangtze Block. Together with compilations of all available high precision zircon U17Pb data on tuff beds in the Nanhua Basin, our work demonstrates that the Cryogenian deposition in South China had three depositional cycles at 831~720 Ma, 1005~842 Ma and 2500~1933 Ma. The dominant age group can be further divided into two sub groups with weighted mean age of 769 and 828 Ma, the youngest grain gives a 206Pb/238U age of 720 Ma. The youngest age population gives a mean 206Pb/238U age of 769 Ma that constrains the onset time of the Sturtian (Chang’an) glaciation to < 770 Ma.The largest age group 750~830 Ma from the Cryogenian sedimentary rocks maybe compare global episodic continental growth and reworking events with possibly coupled Rodinia supercontinent break up. The late Paleoproterozoic (1.9~2.5 Ga) thus appears to have witnessed significant of continental reworking in central Hunan Province.
[杜秋定, 汪正江, 王剑, . 湘中长安组碎屑锆石LA-ICP-MS U-Pb年龄及其地质意义[J]. 地质论评, 2013, 59(2): 334-344.]
DOI:10.3969/j.issn.0371-5736.2013.02.015 URL
The Yangtze Block in South China is one of the important regions in the world where the Neoproterozoic glacial sediments are well developed and well studied. In this paper, we report and analyse the LA-ICP-MS U-Pb ages of detrital Zircon grains from the Jiangkou Group in the Central Hunan, Southeastern Yangtze Block. Together with compilations of all available high precision zircon U17Pb data on tuff beds in the Nanhua Basin, our work demonstrates that the Cryogenian deposition in South China had three depositional cycles at 831~720 Ma, 1005~842 Ma and 2500~1933 Ma. The dominant age group can be further divided into two sub groups with weighted mean age of 769 and 828 Ma, the youngest grain gives a 206Pb/238U age of 720 Ma. The youngest age population gives a mean 206Pb/238U age of 769 Ma that constrains the onset time of the Sturtian (Chang’an) glaciation to < 770 Ma.The largest age group 750~830 Ma from the Cryogenian sedimentary rocks maybe compare global episodic continental growth and reworking events with possibly coupled Rodinia supercontinent break up. The late Paleoproterozoic (1.9~2.5 Ga) thus appears to have witnessed significant of continental reworking in central Hunan Province.
[本文引用: 1]
[55]
Liu Shuo, Zhu Guang, Wu Qi, et al.Reappraisal of protolith ages and formation mechanism for the metamorphic core complex in Hongzhen, Huaining County, Anhui Province[J]. Geological Review, 2016, 62(3): 585-603.
DOI:10.16509/j.georeview.2016.03.005 URL
大别造山带东侧、扬子板块上安徽怀宁县的洪镇变质核杂岩,以往认为是早白垩世NE—SW拉张形成的科迪勒拉型变质核杂岩,其核部的董岭杂岩长期被认为是变质基底。然而,该核杂岩所指示的拉张方向与中国东部一系列早白垩世伸展构造指示的NW—SE拉张相矛盾,从而需要对这一重要伸展构造进行再研究和认识。本次11个样的锆石定年表明,董岭杂岩内变形—变质岩体的侵位时代为829~812 Ma,而变火山岩的原岩时代为761~754 Ma,后者属于扬子板块上的新元古代南华纪盖层。锆石生长边揭示了董岭杂岩内一期127 Ma的热事件,应为旁侧同期洪镇岩体侵位的热影响结果,并影响了董岭杂岩内韧性剪切带白云母~(40)Ar/~(39)Ar年龄值。该区董岭杂岩两侧在早白垩世发育了两组北东走向、倾向相背的正断层,南侧与西侧分别上叠同期的怀宁和潜山断陷盆地。断层擦痕应力场反演结果表明,这些早白垩世伸展构造是在NW—SE拉张中发育的,而不是前人认为的NE—SW拉张。综合分析表明,该区在早白垩世两组倾向相背正断层活动与洪镇岩体侵位、隆升的共同控制下发育为伸展穹窿构造,并非科迪勒拉型变质核杂岩。
[刘硕, 朱光, 吴齐, . 安徽怀宁县洪镇变质核杂岩原岩时代与形成机制再认识[J]. 地质论评, 2016, 62(3): 585-603.]
DOI:10.16509/j.georeview.2016.03.005 URL
大别造山带东侧、扬子板块上安徽怀宁县的洪镇变质核杂岩,以往认为是早白垩世NE—SW拉张形成的科迪勒拉型变质核杂岩,其核部的董岭杂岩长期被认为是变质基底。然而,该核杂岩所指示的拉张方向与中国东部一系列早白垩世伸展构造指示的NW—SE拉张相矛盾,从而需要对这一重要伸展构造进行再研究和认识。本次11个样的锆石定年表明,董岭杂岩内变形—变质岩体的侵位时代为829~812 Ma,而变火山岩的原岩时代为761~754 Ma,后者属于扬子板块上的新元古代南华纪盖层。锆石生长边揭示了董岭杂岩内一期127 Ma的热事件,应为旁侧同期洪镇岩体侵位的热影响结果,并影响了董岭杂岩内韧性剪切带白云母~(40)Ar/~(39)Ar年龄值。该区董岭杂岩两侧在早白垩世发育了两组北东走向、倾向相背的正断层,南侧与西侧分别上叠同期的怀宁和潜山断陷盆地。断层擦痕应力场反演结果表明,这些早白垩世伸展构造是在NW—SE拉张中发育的,而不是前人认为的NE—SW拉张。综合分析表明,该区在早白垩世两组倾向相背正断层活动与洪镇岩体侵位、隆升的共同控制下发育为伸展穹窿构造,并非科迪勒拉型变质核杂岩。
[本文引用: 1]
[56]
Zhao Guochun, Sun Min, Wilde S A, et al.Late Archean to Paleoproterozoic evolution of the North China Craton: Key issues revisited[J]. Journal of Asian Earth Sciences, 2005, 24(5): 519-522.
DOI:10.1016/j.jseaes.2004.06.004 Magsci URL
A recently proposed model for the evolution of the North China Craton envisages discrete Eastern and Western Blocks that developed independently during the Archean and collided along the Trans-North China Orogen during a Paleoproterozoic orogenic event. This model has been further refined and modified by new structural, petrological and geochronological data obtained over the past few years. These new data indicate that the Western Block formed by amalgamation of the Ordos Block in the south and the Yinshan Block in the north along the east-west-trending Khondalite Belt some time before the collision of the Western and Eastern Blocks. The data also suggest that the Eastern Block underwent Paleoproterozoic rifting along its eastern continental margin in the period 2.2-1.9 Ga, and was accompanied by deposition of the Fenzishan and Jingshan Groups in Eastern Shandong, South and North Liaohe Groups in Liaoning, Laoling and Ji'an Groups in Southern Jilin, and possibly the Macheonayeong Group in North Korea. The final closure of this rift system at 鈭1.9 Ga led to the formation of the Jiao-Liao-Ji Belt. In the late Archean to early Paleoproterozoic, the western margin of the Eastern Block faced a major ocean, and the east-dipping subduction beneath the western margin of the Eastern Block led to the formation of magmatic arcs that were subsequently incorporated into the Trans-North China Orogen. Continued subduction resulted in a major continent-continent collision, leading to extensive thrusting and high-pressure metamorphism. The available age data for metamorphism and deformation in the Trans-North China Orogen indicate that this collisional event occurred at about 1.85 Ga ago, resulting in the formation of the Trans-North China Orogen and final amalgamation of the North China Craton. 漏 2004 Elsevier B.V. All rights reserved.
[本文引用: 1]
[57]
Zhang Shuanhong, Zhao Yueqiao, Davis G A, et al.Temporal and spatial variations of Mesozoic magmatism and deformation in the North China Craton: Implications for lithospheric thinning and decratonization[J]. Earth Science Reviews, 2014, 131(4): 49-87.
[本文引用: 1]
[58]
Zhang Shaobing, Zheng Yongfei, Wu Yuanbao, et al.Zircon U-Pb age and Hf-O isotope evidence for Paleoproterozoic metamorphic event in South China[J]. Precambrian Research, 2006, 151(3): 265-288.
DOI:10.1016/j.precamres.2006.08.009 URL
To understand the connection between continental cratonization and global tectonothermal event is essential for recognizing the formation and evolution of continental crust. Paleoproterozoic is an important era with occurrence of megascale tectonomagmatism in the world, but it has been intriguing whether they also influenced the oldest continent in South China. In order to decipher the nature of Paleoproterozoic event in South China, a combined study of zircon U-Pb dating, Hf and O isotope analyses was carried out for metasediments and amphibolite from the Kongling terrane, the only Archean microcontinent outcropped in South China. U-Pb ages of 1.97 ± 0.03 Ga were obtained with low Th/U ratios of 0.01–0.14, indicating that the ages are a record of Paleoproterozoic metamorphic event. δ 18O values of 6511‰ and 658‰ were measured for quartz from the metasediments and garnet from the amphibolite, respectively, suggesting that their sources experienced supracrustal recycling. 07 Hf( t) values of about 616.5 and model Hf ages of about 3.0 Ga were acquired for zircons from the metapelites, suggesting an Archean source. Thus a response to the Paleoproterozoic global tectonothermal event in South China is reworking of Archean continental nucleus. Compared with Archean rocks at Kongling, abrupt changes in K 2O/Na 2O, REE and other trace elements are observed in the Paleoproterozoic metasedimentary rocks. This is interpreted to reflect a change in upper crustal composition at the Archean–Proterozoic boundary. A survey of Paleoproterozoic ages throughout the Yangtze Block suggests that metamorphic event and subsequent magmatic activity occurred in the north, but only magmatic activity in the south. Both metamorphic and magmatic activities are associated with formation of a unified basement responsible for cratonization of the Yangtze Block. This provides a geodynamic connection between the formation of this craton and the global tectonomagmatism in the Paleoproterozoic, marking continental accretion by arc-continent collision orogeny during assembly of the supercontinent Columbia.
[本文引用: 1]
[59]
Li Zhengxiang, Bogdanova S V, Collins A S, et al.Assembly, configuration, and break-up history of Rodinia: A synthesis[J]. Precambrian Research, 2008, 160(1): 179-210.
DOI:10.1016/j.precamres.2007.04.021 URL
This paper presents a brief synthesis of the current state of knowledge on the formation and break-up of the early-Neoproterozoic supercontinent Rodinia, and the subsequent assembly of Gondwanaland. Our discussions are based on both palaeomagnetic constraints and on geological correlations of basement provinces, orogenic histories, sedimentary provenance, the development of continental rifts and passive margins, and the record of mantle plume events. Rodinia assembled through worldwide orogenic events between 1300 Ma and 900 Ma, with all, or virtually all, continental blocks known to exist at that time likely being involved. In our preferred Rodinia model, the assembly process features the accretion or collision of continental blocks around the margin of Laurentia. Like the supercontinent Pangaea, Rodinia lasted about 150 million years after complete assembly. Mantle avalanches, caused by the sinking of stagnated slabs accumulated at the mantle transition zone surrounding the supercontinent, plus thermal insulation by the supercontinent, led to the formation of a mantle superswell (or superplume) beneath Rodinia 40鈥60 million years after the completion of its assembly. As a result, widespread continental rifting occurred between ca. 825 Ma and 740 Ma, with episodic plume events at ca. 825 Ma, ca. 780 Ma and ca. 750 Ma. Like its assembly, the break-up of Rodinia occurred diachronously. The first major break-up event occurred along the western margin of Laurentia (present coordinates), possibly as early as 750 Ma. Rifting between the Amazonia craton and the southeastern margin of Laurentia started at approximately the same time, but only led to break-up after ca. 600 Ma. By this time most of the western Gondwanan continents had joined together, although the formation of Gondwanaland was not complete until ca. 530 Ma.
[本文引用: 1]
[60]
Li Zhengxiang, Li Xianhua, Kinny P, et al.The breakup of Rodinia: Did it start with a mantle plume beneath South China?[J]. Earth and Planetary Science Letters, 1999, 173(3): 171-181.
DOI:10.1016/S0012-821X(99)00240-X URL
Mafic to ultramafic dykes and sills in South China, dated as 828卤7 Ma old, are identical in age to the 827卤6 Ma Gairdner Dyke Swarm in Australia, thought to be of mantle plume origin. These intrusive rocks, accompanied by widespread granite intrusions and rapid unroofing at a lateral extent of ca. 1000 km, and followed by continental rifting, are interpreted to indicate the arrival of a plume head centred beneath South China. This interpretation supports the idea that South China lay between Australia and Laurentia in the Rodinia supercontinent, and suggests that Rodinia breakup may have started with a mantle plume which initiated continental rifting at about 820 Ma ago.
[本文引用: 1]
[61]
Zheng Yongfei, Wu Rongxin, Wu Yuanbao, et al.Rift melting of juvenile arc-derived crust: Geochemical evidence from Neoproterozoic volcanic and granitic rocks in the Jiangnan orogen, South China[J]. Precambrian Research, 2008, 163(3): 351-383.
[本文引用: 1]
[62]
Murphy J B, van Staal C R, Collins W J. A comparison of the evolution of arc complexes in Paleozoic interior and peripheral orogens: Speculations on geodynamic correlations[J]. Gondwana Research, 2011,19(3): 812-827.
DOI:10.1016/j.gr.2010.11.019 Magsci
We discuss the potential geodynamic connections between Paleozoic arc development along the flanks of the interior (e.g. the lapetus and Rheic) oceans and the exterior Paleopacific Ocean. Paleozoic arcs in the Iapetus and Rheic oceanic realms are preserved in the Appalachian-Caledonide and Variscan orogens, and in the Paleopacific Ocean realm they are preserved in the Terra Australis Orogen. Potential geodynamic connections are suggested by paleocontinental reconstructions showing Cambrian-Early Ordovician contraction of the exterior ocean as the interior oceans expanded, and subsequent Paleozoic expansion of the exterior oceans while the interior oceans contracted. Subduction initiated in the eastern segment of Iapetus at ca. 515 Ma and Early to Middle Ordovician orogenesis along the flanks of this ocean is highlighted by arc-continent collisions and ophiolite obductions. Over a similar time interval, subduction and orogenesis took place in the exterior ocean and included formation of the Macquarie arc in the Tasmanides of Eastern Australia and the Famatina arc and correlatives in the periphery of the proto-Andean margin of Gondwana. Major changes in the style of subduction (from retreating to advancing) in interior oceans occurred during the Silurian, following accretion of the peri-Gondwanan terranes and Baltica, and closure of the northeastern segment of Iapetus. During the same time interval, subduction in the Paleopacific Ocean was predominantly in a retreating mode, although intermittent episodes of contraction closed major marginal basins. In addition, however, there were major disturbances in the Earth tectonic systems during the Ordovician, including an unprecedented rise in marine life diversity, as well as significant fluctuations in sea level, atmospheric CO2, and Sr-87/Sr-86 and C-13 in marine strata carbonates. Stable and radiogenic isotopic data provide evidence for the addition of abundant mantle-derived magma, fluids and large mineral deposits that have a significant mantle-derived component. When considered together, the coeval, profound changes in the style of tectonic activity and the disturbances recorded in Earth Systems are consistent with the emergence of a superplume during the Ordovician. We speculate that the emergence of a superplume triggered by slab avalanche events within the Iapetus and Paleopacific oceans was associated with the establishment of a new geoid high within the Paleopacific regime, the closure of the interior Rheic Ocean and the amalgamation of Laurussia and Gondwana, which was a key event in the Late Carboniferous amalgamation of Pangea. (C) 2010 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.
[本文引用: 1]
[63]
Li Renwei, Wan Yusheng, Cheng Zhenyu, et al.Provenance of Jurassic sediments in the Hefei Basin, east-central China and the contribution of high-pressure and ultrahigh-pressure metamorphic rocks from the Dabie Shan[J]. Earth and Planetary Science Letters, 2005, 231(3): 279-294.
[本文引用: 1]
[64]
Xiang Lei, Shu Liangshu.Pre-Devonian tectonic evolution of the eastern South China Block: Geochronological evidence from detrital zircons[J]. Science in China (Series D), 2010, 53(10): 1 427-1 444.
URL
[向磊, 舒良树. 华南东段前泥盆纪构造演化:来自碎屑锆石的证据[J]. 中国科学: D辑, 2010, 40(10): 1 377-1 388.]
URL
[本文引用: 1]
[65]
Yang Kunguang, Ma Changqian, Xu Changhai, et al.Differential uplift between Beihuaiyang and Dabie orogenic belt[J]. Science in China (Series D), 2000, 43(2): 193-199.
DOI:10.3321/j.issn:1006-9267.1999.02.001 URL
采用同位素定年、角闪石压力计法 ,裂变径迹法 ,结合微裂隙内流体包裹体均一温度测定值分析 ,得出北淮阳构造带和大别造山带中加里东期、海西期、燕山期一些岩体的形成年龄和结晶深度 ,从而得出自晚古生代以来北淮阳构造带和大别造山带隆升时间和隆升幅度的差异 :北淮阳构造带经历三个阶段性隆升 (C1~C2 ,T~J2 ,J3 ~K1) ,总隆升幅度约 10km ;大别造山带仅经历二个阶段性隆升 (T~J2 ,J3 ~K1) ,最大隆升幅度大于 15km .前者主体隆升发生在中侏罗世末 (约 150Ma)之前 ,后者主体隆升发生在中侏罗世末 (约 150Ma)之后 .
[杨坤光, 马昌前, 许长海, . 北淮阳构造带与大别造山带的差异性隆升[J]. 中国科学:D辑, 2000, 43(2): 193-199].
DOI:10.3321/j.issn:1006-9267.1999.02.001 URL
采用同位素定年、角闪石压力计法 ,裂变径迹法 ,结合微裂隙内流体包裹体均一温度测定值分析 ,得出北淮阳构造带和大别造山带中加里东期、海西期、燕山期一些岩体的形成年龄和结晶深度 ,从而得出自晚古生代以来北淮阳构造带和大别造山带隆升时间和隆升幅度的差异 :北淮阳构造带经历三个阶段性隆升 (C1~C2 ,T~J2 ,J3 ~K1) ,总隆升幅度约 10km ;大别造山带仅经历二个阶段性隆升 (T~J2 ,J3 ~K1) ,最大隆升幅度大于 15km .前者主体隆升发生在中侏罗世末 (约 150Ma)之前 ,后者主体隆升发生在中侏罗世末 (约 150Ma)之后 .
[本文引用: 2]
[66]
Wang Yongsheng, Wang Haifeng, Sheng Yong, et al.Early Cretaceous uplift history of the Dabie orogenic belt: Evidence from pluton emplacement depths[J]. Science in China (Series D), 2014, 57(5): 1 129-1 140.
[本文引用: 2]
[67]
Suo Shutian, Zhong Zengqiu, You Zhendong.Extensional deformation of post ultrahigh-pressure metamorphism and exhumation process of ultrahigh-pressure metamorphic rocks in the Dabie massif, China[J]. Science in China (Series D), 2000, 43(3): 225-236.
DOI:10.3321/j.issn:1006-9267.2000.01.002 URL
详细构造分析证明,现今观察到的大别地块内部超高压变质地体的区域构造样式,主要是在印支期(240 ̄210Ma)扬子与中-朝克拉通陆-陆碰撞及超高压变质作用期后形成的,具有变质核杂岩和多层伸展拆离带的组合格局,通过鉴别挤压和伸展组构可知,超高压变质岩石由地幔深处折返和剥露于地表,至少经历过3个不同的减压退变及构造变形阶段,其中,角闪岩相条件下的中下地壳近水平的伸展流动是一个重要的折返动力学过程,而且可
[索书田, 钟增球, 游振东. 大别地块超高压变质期后伸展变形及超高压变质岩石折返过程[J]. 中国科学:D辑, 2000, 30(1): 9-17.]
DOI:10.3321/j.issn:1006-9267.2000.01.002 URL
详细构造分析证明,现今观察到的大别地块内部超高压变质地体的区域构造样式,主要是在印支期(240 ̄210Ma)扬子与中-朝克拉通陆-陆碰撞及超高压变质作用期后形成的,具有变质核杂岩和多层伸展拆离带的组合格局,通过鉴别挤压和伸展组构可知,超高压变质岩石由地幔深处折返和剥露于地表,至少经历过3个不同的减压退变及构造变形阶段,其中,角闪岩相条件下的中下地壳近水平的伸展流动是一个重要的折返动力学过程,而且可
[本文引用: 1]
[68]
Wang Qiang, Wyman D A, Xu Jifeng, et al.Early Cretaceous adakitic granites in the Northern Dabie Complex, central China: Implications for partial melting and delamination of thickened lower crust[J]. Geochimica et Cosmochimica Acta, 2007, 71(10): 2 609-2 636.
[本文引用: 1]
[69]
Lin Wei, Ji Wenbin, Faure M, et al.Early Cretaceous extensional reworking of the Triassic HP-UHP metamorphic orogen in Eastern China[J]. Tectonophysics, 2015, 662: 256-270.
[本文引用: 1]
[70]
Chen Yi, Ye Kai, Liu Jinbo, et al.Multistage metamorphism of the Huangtuling granulite, Northern Dabie Orogen, eastern China: Implications for the tectonometamorphic evolution of subducted lower continental crust[J]. Journal of metamorphic Geology, 2006, 24(7): 633-654.
[本文引用: 1]
[71]
Zhu Guang, Song Chuanzhong, Wang Daoxuan, et al.Studies on 40Ar/39Ar thermochronology of strike-slip time of the Tan-Lu fault zone and their tectonic implications[J]. Science in China (Series D), 2001, 44(11): 1 002-1 009.
DOI:10.3321/j.issn:1006-9267.2001.03.010 URL
选择了郯庐断裂带安徽段5处糜棱岩、超糜棱岩、千糜岩进行了40Ar/39Ar年代学研究.大别造山带东缘断裂带上3处4个样品给出了128~132Ma的40Ar/39Ar坪年龄;北部张八岭隆起带西侧和蚌埠隆起东缘断裂带上两处样品一致给出了120Ma的40Ar/39Ar坪年龄.等时线分析及其他证据表明这些数据是可靠的.这些年龄值代表了郯庐断裂带韧性左旋走滑变形的冷却年龄,北部较年轻的年龄值可能与较缓慢的走滑隆起有关.由此表明,郯庐断裂带的大规模左行平移发生在早白垩世,而不是一些学者认为的印支期.该断裂带是滨太平洋的陆内平移断裂,而不是大别-胶南造山带同造山的转换断层或斜向缝合边界.
[朱光, 宋传中, 王道轩,. 郯庐断裂带走滑时代的40Ar/39Ar年代学研究及其构造意义[J]. 中国科学: D辑, 2001, 31(3): 250-256.]
DOI:10.3321/j.issn:1006-9267.2001.03.010 URL
选择了郯庐断裂带安徽段5处糜棱岩、超糜棱岩、千糜岩进行了40Ar/39Ar年代学研究.大别造山带东缘断裂带上3处4个样品给出了128~132Ma的40Ar/39Ar坪年龄;北部张八岭隆起带西侧和蚌埠隆起东缘断裂带上两处样品一致给出了120Ma的40Ar/39Ar坪年龄.等时线分析及其他证据表明这些数据是可靠的.这些年龄值代表了郯庐断裂带韧性左旋走滑变形的冷却年龄,北部较年轻的年龄值可能与较缓慢的走滑隆起有关.由此表明,郯庐断裂带的大规模左行平移发生在早白垩世,而不是一些学者认为的印支期.该断裂带是滨太平洋的陆内平移断裂,而不是大别-胶南造山带同造山的转换断层或斜向缝合边界.
[本文引用: 1]
[72]
Zhu Guang, Niu Manlan, Xie Chenglong, et al.Sinistral to Normal Faulting along the Tan-Lu Fault Zone: Evidence for geodynamic Switching of the East China Continental Margin[J]. Journal of Geology, 2010, 118(3): 277-293.
[本文引用: 1]
Resource
PDF downloaded times    
RichHTML read times    
Abstract viewed times    

Share
Export

External search by key words
大别造山带     
变沉积岩     
锆石定年     
构造演化     

Dabie orogenic belt     
Metasedimentary rocks     
Zircon U-Pb dating     
Tectonic evolution.     

External search by authors
田自强     
王勇生     
胡召齐     
白桥     

Tian Ziqiang    
Wang Yongsheng    
Hu Zhaoqi    
Bai Qiao    

Related articles(if any):