滇西一些新生代飞来峰的构造演化          下载免费PDF全文

王二七  王世锋  樊春  王刚 《地质科学》2006,41(1):170-180

在印度和欧亚大陆相互作用下,滇西三江造山带在新生代中期发生了强烈的东西向缩短,地壳物质的大规模推覆作用形成众多的飞来峰。野外调查发现:这些飞来峰中有的在就位后没有再发生过变形,如分布在兰坪——思茅盆地中段的无量山东北山麓一带的一系列上三叠统灰岩飞来峰;有的飞来峰在就位后再次遭受到强烈的变形,如分布在兰坪盆地金顶一带的上三叠统灰岩飞来峰,在渐新世时与下伏岩层一同卷入了强烈的褶皱变形;分布在大理地区鹤庆盆地西侧的中三叠统灰岩飞来峰因受到后期东西向伸展构造的破坏,已被改造成分选极差的重力滑塌沉积。这些古近纪飞来峰由于在就位后再次发生了变形,所以不应称之为飞来峰,应称为异地岩或者是外来岩块。  相似文献   

喜马拉雅的两个造山体系和一个转换-转移断层:证据及推论   总被引：1，自引：0，他引：1  

Jean-Pierre BURG 《地学前缘》2006,13(4):27-46

位于中喜马拉雅和巴基斯坦境内西喜马拉雅的两个相互结合的剖面在一级单元、断层中展现出不同的构造形式;并在不同时期,以不同速率发育了二级构造。沿两剖面岩性单元的显著差异显示通常指的圆柱状喜马拉雅带并没有越过喀喇昆仑山断层。与此同时,在近来许多区域研究中显示出来的构造轮廓强调主中央逆冲断层是一个貌似与中喜马拉雅断层带和越过西部山脉的西喜马拉雅断层带有联系的独立部分。上述两个地区展现出不同的碰撞历史。这些不同之处揭示喀喇昆仑山断层是西部岛弧保留造山带与东部岛弧俯冲造山带之间转移/转换断层的再活动或衍变。  相似文献   

Anticosti foreland basin offshore of western Newfoundland: Concealed record of northern Appalachian orogen development     

Shawna E. White  John W. F. Waldron  Nicholas B. Harris 《Basin Research》2020,32(1):25-50

The Anticosti Basin, largely hidden beneath the Gulf of St. Lawrence, includes foreland basin successions that record multiple tectonic events associated with the Ordovician to Devonian evolution of the northern Appalachian orogen. Due to the lack of well ties and minimal onshore exposure, geophysical data must be used in mapping the offshore stratigraphy. Outcropping geologic boundaries are tied to magnetic lineaments that parallel stratigraphy. These lineaments are correlated with reflections on seismic profiles in order to interpret the subsurface. Seismic isochron maps for successive basin development episodes display differences in geometry, implying that orogenic loading varied through time. The geometry and subsidence rates recorded by the Middle Ordovician Goose Tickle Group imply that it formed in a pro-arc setting associated with loading during arc-continent collision that was most intense in the northern Newfoundland Appalachians. The geometry and subsidence recorded by the overlying Long Point Group imply pro-arc loading by Taconian allochthons in the Québec segment of the orogen. Diachronous subduction polarity reversal along the margin placed the Long Point Group in a combined retro-arc and pro-arc setting, comparable to that experienced by parts of the north Australian margin at the present day. The uppermost Silurian to Lower Devonian Clam Bank Formation and Lower Devonian Red Island Road Formation represent foreland basin successions associated with the later Salinian and Acadian orogenies. Their consistent thickness implies a broad, shallow basin, suggesting that the lithosphere was cooler and stronger than during earlier subsidence, and are consistent with a retro-arc setting.  相似文献   

高黎贡西北缘早白垩世火山活动与怒江洋俯冲:来自流纹岩岩石地球化学、锆石U-Pb定年和Hf同位素的证据     

戚学祥  沈辉  任玉峰  韦诚  蔡志慧  张超  吉风宝  梁凤华 《岩石学报》2020,36(10):2946-2962

高黎贡构造带西北缘早白垩世火山岩的厘定将为揭示腾冲与保山地块之间的关系补充强有力的证据。本文通过对构造带内高家寨和濮家寨一带的流纹岩进行岩石学、地球化学、锆石U-Pb定年和Hf同位素地质学等方面的研究,并结合前人对同时代侵入岩的研究成果,分析其形成的构造背景。锆石U-Pb定年结果表明高家寨和濮家寨流纹岩的形成时代相同,分别为122±2.2Ma和121±1.9Ma。岩石学和地球化学分析结果说明高家寨和濮家寨流纹岩都属于科迪勒拉型、镁质、弱过铝质-过铝质高钾钙碱性岩类,具有轻稀土富集、分馏程度高、重稀土相对亏损、Eu中度亏损及大离子亲石元素相对原始地幔强烈富集,高场强元素（HSFE）Nb、Ta、P、Ti及Sr强烈负异常的特点;流纹岩的Mg^#值较高,在SiO₂-Mg^#图解上分布于壳源物质部分熔融区上方;锆石ε_Hf（t）值变化范围大（-9.6~-2.6）和t_DM^C值高（1189~1572Ma）;在构造环境判别图解上所有样品落在大陆边缘弧区;流纹岩斑晶中普遍存在黑云母。这些特征与高黎贡构造带早白垩世岩浆岩带内壳幔混源的中酸性侵入岩一致,说明其岩浆主要来源于壳源物质的部分熔融,同时有少量幔源岩浆的混入,是怒江洋壳向腾冲地块下俯冲的结果。  相似文献   

下扬子及其邻区地壳和上地幔结构的接收函数研究及其地质意义     

叶卓  李秋生  张洪双  王晓冉  韩如冰  吴庆宇 《地质学报》2020,94(3):707-715

本文通过对两条宽频地震密集台站剖面记录的远震事件进行接收函数分析,得到了切过下扬子地区的高分辨率地壳和上地幔顶部结构断面。接收函数结果揭示了此区主要块体结构特征以及地表出露晚中生代岩浆岩以及相关矿床下方的深部结构响应:①中生代以来新生或活化的地质构造对下扬子及其邻区地壳结构的控制作用明显;②在大别造山带中下地壳出现低速震相,指示了大别造山带下方地壳深部存在低速物质,可能是大别造山带下方地壳中发育的韧性剪切带,此韧性剪切带可能与大别超高压变质岩被抬升剥露于地表的动力学作用有关;③在江南造山带东段怀玉山地区中下地壳观测到褶皱和逆冲叠瓦状复杂转换震相结构,与江南造山带西段雪峰山地区中下地壳结构相似,可能反映了隐伏的元古代江南造山带;④在德兴矿床和皖南白垩纪花岗岩群正下方观测到Moho和LAB界面的突变上隆现象,可能指示了晚中生代以来在华南东部下扬子地区岩石圈的薄弱区域,软流圈的上涌造成了岩石圈地幔的局部破坏,壳幔结构的局部异常是壳幔物质相互作用的结果。以上地震学观测揭示了下扬子及其邻区下方一些重要的壳幔结构特征,反映了华南大陆东部在不同地质历史时期经历的独特构造演化事件,为我们深入理解华南板块的形成和早期演化以及后期中生代以来华南东部强烈的岩浆和成矿作用的深部机制提供了关键的地球物理约束信息。  相似文献   

喜马拉雅造山带工程效应及中尼铁路工程地质分区     

黄艺丹  姚令侃  谭礼  郭沉稳  LaluPrasad Paudel 《工程地质学报》2020,28(2):421-430

造山带内动力作用的工程效应是地学与工程领域基础科学研究的前沿问题。结合GIS技术和相关地学理论,对喜马拉雅造山带由构造划分的高喜马拉雅、低喜马拉雅和特提斯喜马拉雅3个地块进行研究,揭示不同地块工程地质特性和灾害效应受内动力制约的普适性规律。提出:在挤压碰撞造山机制作用下快速隆升的高、低喜马拉雅,地震以逆冲型为主,地震强度大、频率高,水平应力相对较大,主应力方向近NE-WS方向,地形向大高差发展、河流下切强烈,山地灾害严重;而属于拆离地系,处于相对沉陷状态的特提斯喜马拉雅,地震以正断型为主,地震活动性相对较弱,水平应力相对较小,主应力方向近E-W方向,地形演化向着减弱地势的趋向发展,雪崩灾害严重;此外,高喜马拉雅特有的海洋性冰川地貌、冰湖和冰川泥石流,可能是控制跨喜马拉雅山铁路线路方案的重要问题。基于上述各地块工程效应存在显著差异的认识,提出以构造划分作为铁路工程地质分区的建议,并以拟建中尼铁路交通廊道为例,绘制了工程地质分区图。研究有助于将造山带理论推进到工程应用层面,为铁路大范围方案比选阶段,广域、高效、低成本地获取信息提供了新途径。  相似文献   

Source-to-sink of Late carboniferous Ordos Basin: Constraints on crustal accretion margins converting to orogenic belts bounding the North China Block     

《地学前缘(英文版)》2020,11(6):2031-2052

The Upper Carboniferous Benxi Formation of the Ordos Basin is the lowest strata overlying Middle Ordovician above the major ca. 150-Myr sedimentary gap that characterizes the entire North China Block (NCB). We apply an integrated analysis of stratigraphy, petrography, and U–Pb dates and Hf isotopes on detrital zircons to investigate its provenance and relationships to the progressive collisions that formed the Xing’an-Mongolia Orogenic Belt to the north and the Qinling Orogenic Belt to the south. The results show that, in addition to regional patterns of siliciclastic influx from these new uplifted sources, the Benxi Formation is composed of two sequences corresponding to long-term glacial-interglacial cycles during the Moscovian to lower Gzhelian stages which drove global changes of eustatic sea level and weathering. The spatio-temporal distribution of sediment isopachs and facies indicate there were two sediment-infilling pulses, during which the southern and the northern Ordos Basin developed tidal-reworked deltas. The age spectra from detrital zircons, trace element patterns and ε_Hf(t) values reveal that the siliciclastics forming the southern delta was sourced in the Qinling Orogenic Belt, whereas the northern delta was derived from the Xing’an-Mongolia Orogenic Belt. The source-to-sink evolution of this Upper Paleozoic system records the progressive development of orogenic belts and uplifts forming on the southern and northern margins of the NCB prior to its collisions with the South China and the Siberian plates, respectively.  相似文献   

残余壳根与"三明治"结构——燕山造山带中段地壳结构的主要特征   总被引：3，自引：0，他引：3  

李秋生  高锐  张成科  赵金仁  管烨  张季生 《地球学报》2008,29(2):129-136

摘要昌黎一承德一达莱诺尔宽角反射／折射地震剖面完成于1985年,呈NW向横过燕山造山带中段,部分测段与2002年实施的120km深反射地震剖面重合。为获得区域深部构造背景并在与反射地震剖面交互解释基础上,对该剖面的4炮原始资料进行了处理、解释,获得了一个厚35-38km,局部残余壳根,夹有低速层的“三明治”式的地壳结构模型。该结构样式明显不同于板缘俯冲／碰撞造山带常见的楔入（挤入）样式,也区别于澳大利亚Alice Spring造山带的厚皮变形样式,在世界陆内造山带中独具特色。燕山造山带的地壳结构模型暗示该区保持着中生代区域收缩变形形成的地壳结构基本格架,下地壳和Moho的特征显示了后期区域性伸展作用的影响。  相似文献   

Model study of the upper circulation in the Sulu Sea and its relation to the South China Sea circulation     

CAI Shuqun  HE Yinghui  LONG Xiaomin  WANG Shengan 《海洋学报(英文版)》2008,27(Z1):119-128

According to the satellite remote sensing monthly mean sea surface temperature data from 1998 to 2002, it is shown that, the Sulu Sea is dominated by a cold eddy both in summer and winter. A coupled single-layer/two-layer model is employed here to study the summery and wintry characteristics and dynamic mechanism of the upper circulation in the Sulu Sea. According to the numerical experiments, it is found that, due to the local monsoon stress cud, the upper circulation in the Sulu Sea is dominated by a weak anticyclonic eddy in summer and a strong cyclonic eddy in winter. Once there is a large outflow via the Sibutu Passage flowing out of the Sulu Sea in summer, the upper circulation in the Sulu Sea may be dominated by a cyclonic eddy instead of the normal anti- cyclonic one. Moreover, in summer, the water exchange between the Sulu Sea and South China Sea via the Mindoro and Balabac Straits might have some effect on the separation position and strength of the northward western boundary current next to the Indo - China Peninsula in the southern South China Sea.  相似文献   

大别山超高压变质带深部电性结构及其动力学意义初步研究   总被引：11，自引：6，他引：5       下载免费PDF全文

肖骑彬  赵国泽  詹艳  陈小斌  汤吉  王继军  邓前辉 《地球物理学报》2007,50(3):812-822

通过在大别造山带东部横穿超高压变质带的一条NNE向剖面大地电磁测深资料的分析解释,获得了关于沿剖面的地壳上地幔二维电性结构,显示北淮阳与大别地块是电性差异显著的构造单元,它们之间的界面与晓天—磨子潭断裂对应;晓天—磨子潭断裂倾向北,在中上地壳层位出现错动解耦现象;从地表向深处可划分出4个主要电性层：地表风化层、中上地壳高阻层、壳内相对高导层以及上地幔层;大别地块内中、上地壳层位以高阻层为主,与高压-超高压变质岩分布区对应,高阻层最厚处在岳西—英山之间;在大别地块内,推测存在燕山期花岗质岩浆活动的通道,它们造成了超高压变质岩的进一步抬升,同时影响了大别地块内存在的壳内相对高导层的分布,壳内相对高导层在层位上相差较大.  相似文献