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显生宙中国大地构造演化的古地磁研究 总被引：16，自引：2，他引：16
根据古地磁数据可靠性的试用判据，对华北、杨子、塔里木中国三大稳定地块显生宙的构造古地磁数据做了初步检验，考虑古极点的密集区，选用２２９个古极点以“世”或“纪”为单位进行统计，获得三大稳定地块显生宙综合古地磁视极移曲线。以此为基本依据，结合地质构造、古生物和全球古地理重建图的综合分析，初步探讨了三大稳定地块运动演化的大致轮廓，华北、杨子、塔里木地块碰撞、拼接时限和方式以及华北地块与西伯利亚板块运动演化的关系 相似文献
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新疆准噶尔二台地区晚古生代古极点位置与塔里木、哈萨克斯坦地块同时代极点位置无显著差别。实测古纬度更接近于用哈萨克斯坦极点计算得到的预期古纬度。因此,晚古生代准噶尔地块与哈萨克斯坦地块已是统一的整体。泥盆纪准噶尔地块内的准噶尔洋盆于晚石炭世闭合于乌伦古河一带。西伯利亚板块、塔里木、哈萨克斯坦地块等组成东部劳亚大陆的块体,尽管其运动演化有所差异,但都遵循了以西伯利亚板块为主体大致相同的总的运动演化过程,即晚古生代至中生代早期,由低纬度向高纬度的NW向运动和侏罗纪以来的SEE向运动 相似文献
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川东褶皱带作为华南板块中部的“侏罗山式”褶皱,开始形成于晚古生代.自白垩纪晚期开始,受太平洋板块和印度板块对欧亚大陆挤压的影响,这一构造带乃至华南板块中部又叠加了新的构造变形.但是,目前对于川东褶皱带白垩纪以来的构造演化缺乏足够的认识.位于川东褶皱带东侧、雪峰造山带西麓的沅麻盆地形成于早白垩世.晚白垩世以来,沅麻盆地与川东褶皱带处于同一构造应力场中,因此对盆地内早白垩世红层的古地磁研究对于解释川东褶皱带中生代晚期以来的构造演化有着重要的意义.该研究在沅麻盆地早白垩世红层中开展的古地磁学研究获得了可靠的原生剩磁分量:Ds=15.6°,Is=42.9°,k=118.6,α95=2.6°,表明沅麻盆地自早白垩世以来发生了4.1°±3.0°的顺时针构造转动.对川东褶皱带周缘白垩纪古地磁数据所揭示的地壳旋转变形,与断裂和褶皱轴组成的构造线迹变化之间的线性相关性分析,表明川东褶皱带位于齐岳山断裂带东南侧的部分,受印度板块-欧亚大陆、太平洋板块-华南板块间的挤压作用,自晚白垩世以来累积了约50~93 km的右旋错断量. 相似文献
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中国主要地块显生宙古地磁视极移曲线与地块运动 总被引：65，自引：6，他引：59
基于华北、扬子和塔里木三大地块最新古地磁结果,并重新审视已有的古地磁数据,绘制了三大地块显生宙以来的古地磁视极移曲线.以此为基础,推算了各地块古纬度和取向的变化特征.进而分析了三大地块及其周边地块的运动学特征及相互间的对接和缝合过程.早古生代,华北、扬子、塔里木地块都位于南半球中低纬度地区.华北地块在动力学上是独立的,其运动特征以平移为主,旋转运动为辅;扬子和塔里木地块与冈瓦纳大陆关系密切,塔里木地块很可能在晚奥陶世远离冈瓦纳大陆,在二叠纪与西伯利亚板块对接;我国华北和蒙古联合地块与西伯利亚板块的对接则是在晚保罗世完成的 扬子与华北地块的对接过程是先东后西,东部的对接发生在晚二叠世,对接时结合带位于北纬6°～8°.晚三叠世两地块在西部门合时,结合带位于北纬25°左右.两地块在西部对接的同时,在东部产生了应力释放,使最初俯冲到上地慢的部分陆壳物质被推挤上升,与苏鲁-大别地区的超高压变质岩形成的时代相同.从晚二叠世到早中侏罗世华北与扬子地块以东部为支点经历了大规模的相对旋转.晚侏罗世三大地块在动力学意义上已成为整体.在中国拉萨地块和印度次大陆与中国大陆对接缝合产生的力矩作用下.晚保罗世以来三大地块统一显示了约为20°的顺时针旋转运动. 相似文献
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中国东北地区位于中亚造山带东段,夹持在西伯利亚板块、华北板块和太平洋板块之间,是解决东亚大陆构造演化的关键区域,其中额尔古纳地块和兴安地块位于东北地区西部,是两个十分重要的地质构造单元.横过额尔古纳地块东缘和兴安地块西缘的大地电磁测深剖面揭示了两块体结合带附近的深部电性结构,进而为该区构造演化提供新的电性依据.本文通过对剖面测点数据做标准化处理,并对二维偏离度、构造走向等进行计算与分析,采用非线性共轭梯度(NLCG)算法对TE+TM模式的数据做了二维反演,获得了该剖面的地壳和上地幔电性结构模型,划分出三个典型构造单元:额尔古纳地块东缘、碰撞拼合带和兴安地块西缘.研究结果表明,研究区上地壳基本呈高阻特征,可能为岩浆岩,代表其经历了多期次岩浆作用,而额尔古纳地块东缘和兴安地块西缘中下地壳的高导体反映其地壳非刚性的特点,可能形成于后期伸展环境;拼合带中下地壳存在大范围高导体并与上地幔高导体相连,指示出地幔物质上升的通道,反映出地幔物质的上升作用可能是后期构造伸展的重要动力. 相似文献
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印支地块中生代的古地极位置较华南地块的古地极位置经度偏西、纬度偏南。此现象系印度板块和欧亚板块碰撞后,先是印支地块绕喜马拉雅山系的东枢纽(阿萨姆枢纽)顺时针转动了8°,然后华南地块自西向东移动了大约20°。此解释与主走滑断层迁移模式基本吻合。古地磁数据还表明,虽然红河断裂近期活动为右旋性质,但在印度板块和欧亚板块碰撞初期,它曾是一条调节两板块相互作用的巨大的左旋走滑断层 相似文献
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过去发表的石炭纪古地理重建图存在着不少问题,特别是对亚洲各板块位置的认识上。例如,过去的重建图中华北和华南在石炭纪末都处于北半球40°—50°纬度带,但是,地层古生物资料清楚地表明,它们当时处于热带和亚热带环境。这是因为在编制上述古地理图时(70年代末和80年代初),华南和华北等东亚和东南亚地块还没有可靠的古地磁数据,因而这一地区的地块的位置是由距它们最近的西伯利亚地台的地极位置推算出来的。但是,由于这些地块和西伯利亚地台自石炭纪以来曾发生过相对运动,因此,上述作法是不合理的 相似文献
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吐鲁番山间盆地早白垩世岩石的磁组构和古地磁新结果 总被引：2，自引：0，他引：2
为进一步认识天山褶皱带及其南北两侧块体在印度板块和欧亚大陆始新世碰撞前的古构造格局, 揭示该地区在印度/欧亚大陆碰撞后的总的运动学特征, 我们在中国西部的吐鲁番山间盆地内开展了系统的白垩纪古地磁研究. 经系统热退磁, 绝大多数样品可分离出一具双极性特征的高温剩磁分量. 热退磁特征和岩石磁学结果表明这一高温特征分量主要为赤铁矿所携带. 正的褶皱和倒转检验结果表明此高温特征分量为成岩时或稍后获得的原生剩磁. 与中国西部各块体上所获得的白垩纪古地磁结果相类似, 吐鲁番山间盆地的早白垩世古地磁结果相对于稳定的欧亚大陆之间仍存在一定的倾角偏差. 但磁组构研究表明吐鲁番盆地早白垩世胜金口组砂岩不仅具有较弱的磁化率各向异性度, 且磁化率各向异性度与高温特征剩磁倾角之间几乎没有相关性. 由吐鲁番盆地早白垩世古地磁极与塔里木和准噶尔地块的结果及稳定欧亚大陆的古地磁视极移曲线相对比, 发现吐鲁番山间盆地在新生代印度板块的碰撞和持续挤压下相对于其南侧的塔里木地块未发生明显的构造运动; 但相对于其北侧的准噶尔地块和欧亚大陆之间可能存在明显的南北向构造缩短. 相似文献
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本文基于跨越华夏块体至四川盆地西部的130个线性流动地震台站及其附近90个固定台网台站的观测资料，采用S波接收函数波动方程叠后偏移方法，开展了华南大陆岩石圈结构研究.成像结果显示，研究区岩石圈结构复杂，不同构造单元之间差异显著，构造边界带附近小尺度变化强烈.150 km以上的厚岩石圈主要位于四川盆地，不足100 km的薄岩石圈主要分布于川东褶皱带和华夏块体.雪峰山下方岩石圈厚度显著增加，且以雪峰山为界岩石圈结构和性质存在着显著的东西差异.结合其它地球物理观测得到的地壳-上地幔结构信息，我们提出：（1）四川盆地还保留着厚而冷的克拉通岩石圈根，且岩石圈地幔具有结构分层特征；（2）雪峰山可能是扬子克拉通与华夏块体在西南部的边界；（3）雪峰山以东区域可能经历了岩石圈的减薄和改造，且华南岩石圈的减薄与华北相似，都主体发生在东部地区，造成现今南北重力梯度带两侧强烈的结构差异.研究结果为认识华南大陆的构造演化及其深部动力学提供了地震学约束. 相似文献
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鄂尔多斯地块周缘地震活动周期及迁移特性 总被引：2，自引：0，他引：2
根据中国历史地震资料及现代地震观察资料,研究了鄂尔多斯地块周缘地震活动时间上的周期性及空间上的某些迁移特性。发现:地块周缘的地震活动有700—900年的活跃期;300—400年的活跃幕;20—30年的活跃段。在活跃期中,大震有绕地块周缘逆时针迁移趋势;在活跃幕、段中,中、强震有绕地块周缘顺、逆时针相间转动迁移趋势,并有对角、对边及反向迁移特征。 相似文献
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The South Kitakami Belt in the northeast Japan is unique in presence of a thick Paleozoic–Mesozoic sedimentary rocks. The Permian sedimentary succession in the Maiya area of this belt is divided into the Nishikori, Tenjinnoki, and Toyoma formations, in ascending stratigraphic order. The Tenjinnoki Formation includes the Yamazaki Conglomerate Member containing granitic clasts. We performed U–Pb dating for detrital zircon of one sample of tuffaceous sandstone from the Nishikori Formation, six samples of sandstone from the Tenjinnoki and Toyoma formations, and five granitic clasts from the Yamazaki Conglomerate using laser ablation-inductively coupled plasma-mass spectrometry. Our dating results show that the tuffaceous sandstone sample has two age peaks at 287 and 301 Ma for the Nishikori Formation, three age peaks at 320–300, 290, and 270 Ma for the Tenjinnoki and Toyoma Formation, and ages of 311, 300, and 270 Ma from granitic clasts of the Yamazaki Conglomerate. In addition, older ages of 452–435 and 380 Ma were obtained from some zircon grains of the sandstone and granitic clasts. Our results suggest igneous activity in these periods. The South Kitakami Belt's origin with respect to continental blocks has been discussed in regard of the margin of North China Block or South China Block. Based on the stratigraphic ages and timing of igneous activity, we conclude that during the Permian the South Kitakami Belt was located at the margin of the South Central Asian Orogenic Belt, near the Solonker-Xra Moron-Changchun suture and the North China Block in East Asia. 相似文献
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利用中国大陆以及最近与俄罗斯拼接的中亚地区的布格重力和地形数据，采用响应函数和互相关函数技术，结合弹性板挠曲理论，研究了中国大陆及其邻近地区（２５°Ｎ－７０°Ｎ，５０°Ｅ－１４０°Ｅ）的岩石层强度，用现代均衡的观点探讨了研究区的均衡补偿机制．研究结果表明，整个中国大陆及其邻近地区的有效弹性厚度Ｔｅ值为３５ｋｍ．其中，青藏地区Ｔｅ值为８５ｋｍ．西伯利亚西部至乌拉尔Ｔｅ值为７５ｋｍ，天山、塔里木盆地Ｔｅ值为４０ｋｍ，帕米尔高原Ｔｅ值为２５ｋｍ左右，西伯利亚中部、蒙古以及中国东北北部Ｔｅ值为４０ｋｍ，华北Ｔｅ值为２５ｋｍ，华南Ｔｅ值为４０ｋｍ．均衡补偿对于波长大于几千米的地形负荷为局部补偿，对几百公里到１１００ｋｍ的地形负荷为局部补偿和岩石层强度所支持，短波长地形负荷基本上由岩石层强度所支持． 相似文献
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1994年完成的大别造山带深地震测深剖面（全长420km）穿越了华北地块,大别造山带和扬子地块三个构造单元．获得了垂向成层、横向分块的地壳纵、横波速度结构．结合地质、地球化学研究成果,大别山地壳可分为三层：上地壳是多重叠覆的构造岩石层,中地壳为韧性变形层,下地壳整体成分偏酸性．大别山地表及浅部的超高压变质岩石具有典型的薄皮构造特征．本文提出大别山不同期双向俯冲造山模式和超高压变质岩石的反向加楔退拔折返机制;大别山腹地至今仍保留6-8km厚的山根． 相似文献
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南北地震带强震迁移特征及其与南亚地震带的联系 总被引：7，自引：0，他引：7
南北地震带1500年以来7级以上强震迁移显示出3种方式:由北往南大致等时距的迁移、由南往北多样式的迁移和一个时段内全带范围内的成组强震群发活动。从以往100年的强震活动分析,南北地震带的活动还与从缅甸至印尼苏门答腊的南亚地震带强震活动相关联,前者的强震往往滞后于后者几月至数年发生。因此,2004年12月26日苏门答腊岛西面海里发生8·7级大地震后南北地震带发生强震的可能性不能忽视。南北地震带上述多种强震迁移活动特征既与印度板块向NNE的碰撞、俯冲过程有关,也与青藏高原与其东北缘稳定、坚硬的鄂尔多斯和阿拉善块体的相互作用有关 相似文献
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Paleomagnetic constraints on the tectonic history of the major blocks of China duing the Phanerozoic
Zhu Rixiang Yang Zhenyu Wu Hanning Ma Xinghua Huang Baochun Meng Zifang Fang Dajun 《中国科学D辑(英文版)》1998,41(2):1-19
Paleomagnetic study of China and its constraints on Asia tectonics has been a hot spot. Some new paleomagnetic data from three major blocks of China. North China Block (NCB), Yangtze Block (YZB) and Tarim Block (TRM) are first reported, and then available published Phanerozoic paleomagnetic poles from these blocks with the goal of placing constraints on the drift history and paleocontinental reconstruction are critically reviewed. It was found that all three major blocks were located at the mid-low latitude in the Southern Hemisphere during the Early Paleozoic. The NCB was probably independent in terms of dynamics. its drift history was dominant by latitudinal placement accompanying rotation in the Early Paleozoic. The YZB was close to Gondwanaland in Cambrian, and separated from Gondwanaland during the Late-Middle Ordovician. The TRM was part of Gondwanaland, and might be close to the YZB and Australia in the Early Paleozoic. Paleomagnetic data show that the TRM was separated from Gondwanaland during the Late-Middle Ordovician, and then drifted northward. The TRM was sutured to Siberia and Kazakstan blocks during the Permian, however, the composite Mongolia-NCB block did not collide with Siberia till Late Jurassic. During Late Permian to Late Triassic, the NCB and YZB were characterized by northern latitudinal placement and rotation on the pivot in the Dabie area. The NCB and YZB collided first in the eastern part where they were located at northern latitude of about 6°—8°, and a triangular oceanic basin remained in the Late Permian. The suturing zone was located at northern latitude of 25° where the two blocks collided at the western part in the Late Triassic. The collision between the two blocks propagated westward after the YZB rotated about 70° relative to the NCB during the Late Permian to Middle Jurassic. Then two blocks were northward drifting (about 5°) together with relative rotating and crust shortening. It was such scissors-like collision procedure that produced intensive compression in the eastern part of suturing zone between the NCB and YZB, in which continental crust subducted into the upper mantle in the Late Permian, and then the ultrahigh-pressure rocks extruded in the Late Triassic. Paleomagnetic data also indicate that three major blocks have been together clockwise rotating about 20° relative to present-day rotation axis since the Late Jurassic. It was proposed that Lahsa Block and India subcontinent successively northward subducted and collided with Eurasia or collision between Pacific/Philippines plates and Eurasia might be responsible for this clockwise rotating of Chinese continent. 相似文献
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In order to study the present crustal movement and geodynamics in China‘s continent, a countrywide GPS monitoring network consisting of 22 stations was set up evenly on major tectonic blocks in China‘s continent in the early 1990s. Three-phase observations using the network were carried out in 1992, 1994, and 1996, respectively. In this paper, the data processing and accuracy of the three-phase observations are examined and the basic characteristics of present block movement in China‘s continent are analyzed based on the data of three-phase repeated observations. The study result indicates that the accuracy of data obtained in three-phase observations on the GPS network reaches 10-8 ～ 10-9, which is adequate to the need of monitoring of crustal movement. A model for block movement in China‘s continent constructed based on the result of the three-phase observations has effectively tested the results of geological and geophysical studies. In global framework, China‘s continent as a whole shows its clear eastward motion and its regional movement relative to Siberian block is characterized by that the western China is mainly affected by northward subduction and pushing of Indian Plate. Qinghai-Xizang Plateau shows clear eastward lateral slip simultaneously with longitudinal compression. It is more favorable to the escape model for the continent. Block movement of eastern China is under the combined effect of Indian, Pacific,and Philippine plates, resulting in northeastern and eastern motions of eastern China up to southeastern coastal region where the effect of Philippine Plate strengthens. 相似文献