岩石有限应变与造山带构造块体变形要素的估算

提出定量研究造山带的一种简便而实用的方法。利用岩石应变测量方法测量出岩石中变形标志体长轴、中间轴、短轴之间的比值(X∶Y∶Z),计算构造块体的三轴比率;假设变形前后体积不变,可估算出构造块体的原始宽度;若已知构造块体其中一个轴(如Z轴)的长度,便可估算出其它两个轴的长度,近而估算出构造块体变形前后的缩短分量和缩短率、伸展分量和伸展率、垂向伸展量、垂向伸展率、剥蚀量和深部调整量等,从而进一步研究整个造山带的变形要素。     

大别山北部桃花岭岩体年代学、地球化学特征及构造意义

由于缺少可靠的年代学资料和系统研究,大别山北部桃花岭岩体的时代和成因背景尚不清楚.MC-ICP-MS锆石U-Pb分析结果显示,桃花岭正长花岗斑岩侵位于154±1 Ma,花岗闪长岩侵位于142±1 Ma,表明桃花岭岩体是形成于侏罗纪末-早白垩世的复式岩体.地球化学分析表明,桃花岭花岗岩为高钾钙碱性、准铝质-弱过铝质的I型...     

秦岭-大别山北部后造山期构造格架与形成机制

秦岭造山带是一条复合型大陆造山带.东秦岭北部后造山期的构造是其主要组成部分.主要包括秦岭北缘反冲推覆构造带,以宜阳-鲁山断裂带和熊耳岩片为主体,由S→N逆冲推覆;栾川-伏牛山推覆构造带特征典型,分带性强,由N→S推覆;马超营走滑转换构造带位于二者之间,为一正花状构造带.上述构造组成典型的扇形结构,形成于燕山期末-喜马拉雅初期.东秦岭造山带岩石圈现今几何学模型和流变学分带结构与华北地块向南俯冲在秦岭地块之下、扬子地块持续向北俯冲有密切的成因联系,后造山期构造正是研究区现今深部过程在地壳浅部的表现.     

秦岭大别山造山带内巨型构造混杂岩带的组成及构造意义

平行或近平行分布于秦岭大别山造山带的一个巨型构造混杂岩带,由变质表壳岩块、中深地壳变质块体、壳幔过渡带岩块和幔源岩块与糜棱岩和变晶糜棱岩基质共同组成。由构造混杂岩带内岩块和基质的变质变形特点、流变学性质、运动学标志、形成构造环境、动力学特征和时限,表明它们是华北陆块、扬子陆块和分布其间的地体并置碰撞对挤逆冲韧性剪切作用过程中多阶段长时期发育而成。空间上构造混杂岩带内岩块成分的多样性,反映造山带内物质组成的非均一性,也说明地壳隆升剥露的不一致性。这些资料可为深入认识秦岭大别山造山带的地壳组成、结构和构造演化提供重要的地质依据。     

东秦岭-大别造山带南缘印支期以来构造层序耦合特征分析

通过对东秦岭-大别山造山带南缘鄂东地区、荆当盆地、秭归盆地和川东北地区三叠纪-古近纪的构造层序对比研究,划分出三个大的构造层序,并分析了中上扬子地区印支期以来沉积盆地性质转换和迁移过程与构造层序的耦合关系,揭示了东秦岭-大别造山与成盆作用过程.认为早三叠世至中三叠世构造层序Ⅰ记录了扬子地台由克拉通盆地逐渐萎缩的过程,反映了印支期华北板块与扬子板块之间软碰撞未造山的过程;晚三叠世至早白垩世构造层序Ⅱ记录了前陆盆地的三次幕式演化过程,反映了早燕山期华北板块与扬子板块之间呈斜向、剪刀式由东向西陆-陆碰撞关闭以及前展逆冲叠置造山作用过程,与江南逆冲带联合作用形成前陆盆地沉降和沉积中心向西的迁移.晚白垩世至古近纪区域构造背景发生重大变化,构造层序Ⅲ记录了晚燕山期地壳快速均衡隆升,伸展断陷盆地形成演化过程.     

西昆仑造山带主要变形期的磁性组构特征及其构造意义

文章对西昆仑造山带各构造单元主要变形期的岩石磁性组构特征进行了初步的研究。确定了前加里东变形期，加里东—早华力西变形期的变形机制、应变状态和运动学特征及其构造意义。     

利用地震地磁数据浅析大别造山带东段构造活动特征

自2012年以来，在东大别造山带内与郯庐断裂南段等重点地震地磁监测区布设的77地磁三分量测点数据为基础，利用匹配滤波法结合偏移抽样化极方法和阻尼因子方法降低纬度斜磁化的影响，给出研究区域磁异常，为深部地质构造推断或区域构造分析提供依据。     

秦岭—大别造山带中几条重要构造带的特征及其意义

目的 研究秦岭一大别造山带内几条重要构造带的构造变形特征,以探讨其动力学过程.方法 通过该造山带中各构造带的几何学、运动学特征研究,分析板块构造体系向陆内构造体系转换和大陆动力学体系演化等地质过程.结果 ①洛栾构造带是二郎坪弧后盆地与华北板块南缘的陆内构造拼合带,形成于365 Ma±,挤压方向为240→60°;②商丹断裂带在260 Ma±形成,挤压方向为220→40°,以压扁作用为主,正花状构造,显示出板块碰撞带的构造特征;③襄广断裂带是扬子板块在220 Ma±,由185→5°方向与大别造山带斜向汇聚的结果;④殷马断裂带为一条右行平移的韧性剪切带;⑤武穴构造对接带是大别造山带南缘与扬子板块北缘的构造复合带,是在140 Ma±扬子板块总体由S→N挤压所致;⑥宜鲁构造带是东秦岭造山带北界,为S→N逆冲的叠瓦状推覆构造,上地壳缩短率为52%;⑦郯庐断裂带是秦岭一大别造山带东端的一条多期活动的剪切带.结论 秦岭一大别造山带经历了不同构造体制转换、板块构造系统发展、板块构造体系向陆内构造体系转换以及大陆动力学体系发展演化等地质过程;显示出古生代以来逆时针"转动挤压"到"三面围限"的动力学过程.     

大别山造山带研究的主要进展及存在的问题

回顾了1990年以来在大别山超高压变质带研究中取得的主要进展及存在的问题。包括：在大别山北部超镁铁岩带内发现榴辉岩,根据榴辉岩的发现以及同位素定年,解释了超镁铁岩带的构造背景;强调了岩石构造单位的正确划分对研究大别山地质的重要意义。对现行的岩石构造单位划分的分歧意见以及由此产生的对几何结构的不同认识进行了评述。     

勉略带三岔子蛇绿岩的变质特征及构造意义

勉略带是近年来秦岭造山带研究中揭示出来的代表晚古生代小洋盆的缝 合带,组成复杂,它们经历了不同的变质、变形改造、构成了不同构造背景、不同构造层次、不同物质组成、具有不同PTt轨迹揭示,秦岭造山带勉略带三岔子蛇绿岩中的变质辉长岩是由上地幔先处于伸展背景下等温快速降压,后又经历缓慢降压快速温上升侵位的。变形前的早期变质可能发生在60－70km处的地上幔,然后变质辉长岩快速“底辟”构造侵位,上升至约40km深处,可能与俯冲的冷洋壳并置,发生快速降温退变反应;因俯冲作用的开始,抑制了洋盆快速扩张,变质辉长岩在减速伸展环境下继续抬升减压;后期又由于仰冲推覆,最终出露地表。此外,变质作用PTt轨迹还反映勉略小洋盆洋壳厚度与标准大洋型洋壳厚度差异较大。     

大别山(六安)国家地质公园生态旅游资源及开发利用

经过对大别山(六安)国家地质公园自然和人文生态旅游资源进行调查研究表明:该园区内自然生态旅游资源十分丰富,人文生态旅游资源特色鲜明,区位适中且客源市场大,交通网逐步完善。但目前存在政府支持力度不够、基础设施落后、旅游软环境欠佳、品牌效应较差、缺乏具有吸引力的旅游商品等问题。提出了加大资金投入,改善景区基础设施建设,建立以天堂寨为核心、周围各色景点连成一线的精品生态旅游线路,做好生态旅游规划等开发措施与建议。     

Discovery of the eclogite and its petrography in the Northern Dabie Mountain

Eclogite from the Northern Dabie Mountain is a new finding by the authors. These eclogites in foliated perdotite are enveloped by banded gneiss and occur in the mafic-ultramafic rock belt. They are mainly composed of omphacite, garnet, diopside, orthopyroxene, amphibole, plagioclase and magnetite, and a small amount of rutile, spinel, olivin and 鏾rundum. The mineral association of peak metamorphism of the eclogite is omphacite+garnet+rutile. The existence of eclogite in the Northern Dabie Mountain implies that there was an eclogitic metamorphism prior to the granulitic facies one in the mafic-ultramafic rock belt.     

Sm-Nd isochron age of ophiolite along northern margin of Altun Tagh Mountain and its tectonic significance

An ophiolite belt is exposed to the northern edge of Altun Tagh Mountain. Geochronological researches were made on gabbro and basalt. Sm-Nd isochron age of gabbro is (829 ± 60) Ma, while the age of gabbro mixed basalt is (949 ± 62) Ma. The dating of Sm-Nd isochron proves that ophiolite formed in (829 ± 60) Ma, which implies that the northern half of Tarim (or north Tarim Block) had been separated by an ocean from the southern half of Tarim and Qaidarn (or south Tarim Block) until (829 ± 60) Ma. The south Tarim Block could accrete to the north Tarim Block at the beginning of Sinian, thereby forming the north Altun Tagh suture. The Sinian system would be the first cover on the amalgamated Tarim craton.     

Evolution of the Xiaotian-Mozitan fault and its implications for exhumation of Dabie HP-UHP rocks

The Xiaotian-Mozitan fault (XMF) located north of Dabie orogenic belt separates the North Dabie complex to the south from the Beihuaiyang low-grade metamorphic rocks to the north. It comprises several NW-striking ductile shear zones and brittle faults. The brittle faults obviously overprinted on the ductile shear zones and promoted the development of the volcanic basins in early Cretaceous to the north, which suggests that the brittle faults were normal faults formed in early Cretaceous during doming of Dabie orogenic belt. The ductile shear zone superposed on the north Dabie grey gneiss, and it is an important channel where the Dabie HP-UHP rocks exhumed. For obtaining new structural constraint on exhumation of the HP-UHP rocks, we present here experimental results on the microstructure, quartz C-axis fabrics and the microprobe analyses of phengite. The ductile shear zone was determined to be formed at temperature of 600-650℃ and pressure of 1.1 GPa by the mineral deformation, microprobe analyses and geobarometry of Si-in-phengite of the mylonite, the results suggest that the mylonite now exposed on the surface experienced an upper amphibolite-facies metamorphism in the lower crust. The mineral stretching lineation varies from horizontal in the east segment to sub-dip in the west. Shear sense indicators from outcrop and thin sections of orientated specimen and quartz C-axis fabrics suggest that the XMF is a sinistral normal fault. The kinematics analysis of the ductile shear zone indicates that the exhumation of Dabie HP-UHP rocks is the results of a SE-directed extrusion and an anticlockwise rotation around its eastern pivot simultaneously.     

Discovery of granulite from the Fuping area in southern Qinling Mountains and its geological significance

Two-pyroxene-bearing granulites were discovered for the first time in the Hercynian-Indosinian metamorphic belt of the southern Qinling Mountains. The granulites occur in the lower part of the Fuping complex and are dominated by intermediate-acidic rocks intercalated with a small amount of bands and lenses of basic granulites. The main metamorphic minerals include orthopyroxene, clinopyroxene, biotite, plagioclase and quartz, and orthopyroxenes are often retrogressively transformed into amphiboles. The metamorphic conditions have been estimated to be %T%=720-780℃ and %P%=0.6 GPa. The granulite-bearing Fuping complex probably belongs to early Proterozoic in age. Whether it occurs as the crystalline basement of the southern Qinling Hercynian-Indosinian orogenic belt or as a thrusted slice in the collisional process needs further study.     

Evolution of the Xiaotian-Mozitan fault and its implications for exhumation of Dabie HP-UHP rocks

The Xiaotian-Mozitan fault （XMF） located north of the Dabie orogenic belt separates the North Dabie complex to the south from the Beihuaiyang low-grade metamorphic rocks to the north. It comprises several NW-striking ductile shear zones and brittle faults. The brittle faults obviously overprinted on the ductile shear zones and promoted the development of the volcanic basins in early Cretaceous to the north, which suggests that the brittle faults were normal faults formed in early Cretaceous during doming of the Dabie orogenic belt. The ductile shear zone superposed on the north Dabie gray gneiss, and it is an important channel where the Dabie HP-UHP rocks exhumed. For obtaining new structural constraint on exhumation of the HP-UHP rocks, we present here experimental results on the microstructure, quartz C-axis fabrics and the microprobe analyses of phengite. The ductile shear zone was determined to be formed at a temperature of 600-650 ℃ and pressure of 1.1 GPa by the mineral deformation, microprobe analyses and geobarometry of Si-in-phengite of the mylonite, the results suggest that the mylonite now exposed on the surface experienced an upper amphibolite-facies metamorphism in the lower crust. The mineral stretching lineation varies from horizontal in the east segment to sub-dip in the west. Shear sense indicators from outcrop and thin sections of orientated specimen and quartz C-axis fabrics suggest that the XMF is a sinistral normal fault. The kinematics analysis of the ductile shear zone indicates that the exhumation of Dabie HP-UHP rocks is the results of a SE-directed extrusion and an anticlockwise rotation around its eastern pivot simultaneously.     

大别山（六安）国家地质公园皖西大裂谷的地学成因研究

通过对大别山（六安）国家地质公园皖西大裂谷园区的地质地貌考察，以及对皖西大裂谷形态特征的实地调研和分析，初步得出其地学成因机制：①大别山构造抬升形成的山前盆地---凤凰台盆地构造是形成皖西大裂谷的构造背景；②凤凰台组砾岩与砂岩互层是其物质基础；③区域构造断裂是其形成的内在动力前提；④重力崩塌作用、流水作用以及风力作用等是其进一步不断深入侵蚀的外力基础。对皖西大裂谷地学形成机理的探究，有助于大别山（六安）国家地质公园地学科普价值的实现和提高。     

湘西南-桂北交界地区加里东期基性岩的发现及其地质意义

湘西南-桂北交界地区属于江南造山带(或称之为钦杭结合带)西南段的重要组成部分,该区与Rodinia超大陆聚合与裂解有关的岩浆活动十分强烈,但至今还没有加里东期基性岩存在的报道。采用LA-ICP-MS锆石U-Pb法对湘西南—桂北交界地区首次发现的加里东期变辉长辉绿岩进行了年代学研究。结果表明,变辉长辉绿岩形成于(421.9±7.8)Ma,为加里东期岩浆活动的产物。该基性岩的发现及其年龄的确定;并结合区域上的研究结果表明,扬子板块和华夏板块结合带(钦杭结合带)西南段可能存在有从新元古代至早古生代的双向洋陆俯冲-碰撞过程。     

Discovery of Late Carboniferous strata and their tectonic significance in the southern margin of the North China Block （Huoqiu and Gushi areas）

Late Carboniferous fossils （such as Boultonia？ sp., Tabulata, and spiriferoid specimens with smooth she/Is）, bioclastic material （such as crinoid stems and sponge fragments）, and Late Ordovician microfossils of the conodont Belodina have been discovered in the lower part of the strata typically referred to as the Neoproterozoic on the boundary of the provinces of Anhui and Henan in the southern margin of the North China Block. These findings prove that the strata contain macrofossils belonging to the Late Carboniferous, which belonged to a carbonate debris flow deposit that was formed under a carbonate slope environment. The conodont fossils might belong to a detrital deposit. Thus, it is possible to reset the stratigraphic sequences and tectonic attributes belonging to the North Huaiyang tectonic belt and limit the Shouxian fault to the boundary between the Dabie Orogen and North China Block.