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研究板内的大变形与运动学是当今国际岩石圈计划和大陆动力学中的前沿研究课题。众所周知,青藏高原及其周缘是印度板块与欧亚板块碰撞造山的结果,它在全球构造中占有特殊的地位,因而,中外地学科学家都把青藏高原视为研究地球动力学最好的地区之一。“八五”期间,国家自然科学基金资助的重点项目“滇川西部特提斯带构造变形与运动学研究”就选择了国际地学界的研究“热点”——藏东、滇西北为突破口。 相似文献
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裂谷盆地在全球范围内广泛分布,是极其重要的含油气盆地,不同地区裂谷盆地构造演化的特征不同:欧洲裂谷盆地发育在古生代造山缝合线之上,主要在二叠纪-三叠纪时期发育;非洲裂谷盆地的发育与冈瓦纳大陆解体有关,是非洲大陆板内和边缘伸展作用的结果,侏罗纪时期,冈瓦纳在非洲西北部与劳亚分离,与此同时或稍后,在东南部与印度-澳洲板块分离,白垩纪早期,冈瓦纳内部非洲大陆与南美分离,古近纪,非洲东北部与阿拉伯板块分离。亚洲裂谷盆地主要形成于太平洋板块向欧亚板块的俯冲,主要在新生代发育,裂谷阶段后期一般经历构造反转碰撞造山;北美裂谷盆地数量较少,形成于冈瓦纳古陆裂解时期,构造演化特征表现为基底及前裂谷发育阶段较长,同裂谷演化阶段较短。 相似文献
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青海省柴达木盆地西部锶矿成矿古地理环境 总被引：2，自引：0，他引：2
柴达木盆地西部锶矿床具有明显的热水沉积层控矿床特征,晚第三系和早更新世湖相沉积地层为锶矿较集中的赋存地层,尤以上新统狮子沟组上部层位是全区的主要的赋矿地层;锶矿的成矿物质来源具多源性,但主要来源于盆地周边山系岩石的风化剥蚀,其次为深部含锶水的补给;区内锶矿成矿系统位于印度板块与欧亚板块碰撞带的前陆盆地内的湖盆中远离大河补给水的滨、浅湖区,其成矿作用发生在陆陆碰撞造山带的前缘;成矿构造和成矿流体对锶矿的形成起着重要的控制作用。其中锶矿床是在柴达木盆地上新世古湖盆中形成的,盆地中央凹陷的高山深盆区域古地理环境是锶矿形成的主要因素。 相似文献
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鲁山-宝丰地区是河南省重要的铝土矿成矿区之一,区内铝土矿床为沉积型一水硬铝石矿床,矿石具有高铝、高硅、低铁的特征。铝土矿床的形成与分布受古地形、古地貌的控制,矿体形态多为透镜状或漏斗状。燕山期构造运动,改造先期的构造格局,一方面为开展铝土矿找矿提供了有利条件,另一方面使铝土矿层经风化淋滤,为去硅、去硫、富铝提供了良好的自然地质环境。 相似文献
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提起"地震"这两个字不禁使人想起31年前那场震惊世界的唐山大地震。世事变迁,时间冲淡了忧伤,但对于地震的思考,却从来没有停止过。我国大陆地处欧亚板块的东南隅,东邻太平洋板块,南有印度板块和菲律宾海板块。由于印度板块与欧亚板块陆陆碰撞和太平洋板块的俯冲作用,地壳发生了强烈的变形。菲律宾海板块与我国大陆的碰撞俯冲作用则导致了我国台湾地区地壳隆升。强烈地震频繁发生。这种基本的地质构造背景决定了我国必然长期面对大范围地震频繁活动和破坏性地震频发的局面。我们无法改变我国的地理状态,但是却可以竭尽全力使灾难带来的伤害减小。我们的专家学者秉持为国分忧,为民解难的信念,几十年如一日,探索地震的成因、钻研灾害性地震的预测方法,一直在寻求一条将地震灾害降低到最小的道路。中国地震局岩石圈台阵地震学实验室主任刘启元研究员,把青春和热情镌刻在这条道路上,千帆舞尽,回首处,只见坚实的脚印与无悔的人生。 相似文献
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迪彦庙蛇绿岩位于内蒙古西乌旗东,北侧距二连浩特-贺根山-霍林格勒-黑河碰撞带百余公里,南侧离西拉木伦构造碰撞带约300余公里,大地构造位置为中朝古板块和西伯利亚古板块之间的兴蒙造山带,前人将该区基性-超基性岩块作为华力西期侵入岩研究,确定其为绿泥岩.绿泥岩是一套特殊的镁铁岩的共生组合,一套完整的绿泥岩自下而上为:变质橄榄岩,堆积杂岩,席状岩墙群,喷出岩.辉长岩是堆积杂岩的主要组成部分.有人认为典型蛇绿岩均发育有厚层具堆积结构的层状辉长岩,并把无层状辉长岩的类似组合称为似蛇绿岩;也有人认为蛇绿岩中层状辉长岩是不可缺失的.而该区辉长岩较为发育,这对研究该区蛇绿岩,进而研究华北板块和西伯利亚古板块碰撞缝合位置具有重要意义. 相似文献
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中国大陆热流分布特征及热-构造分区 总被引：16，自引：0，他引：16
根据中国大陆822个实测热流数据,研究了中国大陆主要构造单元的深部地热特征,包括40km深度的地温值、热岩石圈厚度、岩石圈累积强度和有效弹性层厚度(EET)等.结果显示,中国大陆热流的空间分布以及岩石圈热状态和流变学特征均表现出明显的横向非均匀性.这源于太平洋板块俯冲和印度-亚洲碰撞导致的新生代构造热活动.根据热流值和深部地热参数,中国大陆可以划分为东部、中部和西部三个大尺度热-构造区. 相似文献
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Robert A Spicer Tao Su Paul J Valdes Alexander Farnsworth Fei-Xiang Wu Gongle Shi Teresa E V Spicer Zhekun Zhou 《国家科学评论(英文版)》2021,8(1)
The often-used phrase ‘the uplift of the Tibetan Plateau’ implies a flat-surfaced Tibet rose as a coherent entity, and that uplift was driven entirely by the collision and northward movement of India. Here, we argue that these are misconceptions derived in large part from simplistic geodynamic and climate modeling, as well as proxy misinterpretation. The growth of Tibet was a complex process involving mostly Mesozoic collisions of several Gondwanan terranes with Asia, thickening the crust and generating complex relief before the arrival of India. In this review, Earth system modeling, paleoaltimetry proxies and fossil finds contribute to a new synthetic view of the topographic evolution of Tibet. A notable feature overlooked in previous models of plateau formation was the persistence through much of the Cenozoic of a wide east–west orientated deep central valley, and the formation of a plateau occurred only in the late Neogene through compression and internal sedimentation. 相似文献
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亚洲内陆是北半球最大、最广阔的中纬度干旱区,且不同于世界上分布于副热带高压控制下的干旱区。现今的亚洲中纬度干旱区深居内陆,远离各大洋的水汽来源。亚洲中纬度干旱区究竟如何形成?历经了怎样的干旱化过程?其形成演化的动力机制是什么?这些一直是悬而未决的问题。事实上,亚洲中纬度干旱区发展成今天所见的干旱荒漠,并不是短时间内实现的,而是经历了漫长的阶段性演化进程,是在新生代以来印度、阿拉伯、非洲板块与欧亚大陆的碰撞,青藏高原的隆升,新特提斯海的退却以及新生代全球气候变冷与海平面下降等区域和全球要素共同作用下,从半湿润—半干旱—干旱—极端干旱渐进演化而来。历经了始新世的半湿润气候,渐新世的半湿润-半干旱气候和中新世末期以来的干旱-极端干旱气候。 相似文献
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Qun-Ke Xia Jia Liu Istvn Kovcs Yan-Tao Hao Pei Li Xiao-Zhi Yang Huan Chen Ying-Ming Sheng 《国家科学评论(英文版)》2019,6(1):125
Understanding the concentration and distribution of water in the Earth''s mantle plays a substantial role in studying its chemical, physical and dynamic processes. After a decade of research, a comprehensive dataset of water content in upper-mantle samples has been built for eastern China, which is now the only place with water-content data from such diverse types of natural samples, and provides an integrated picture of the water content and its distribution in the upper mantle at a continental scale. The main findings include the following: (i) the temporal heterogeneity of the water content in the lithospheric mantle from early Cretaceous (∼120 Ma) to Cenozoic (<40 Ma) was tightly connected with the stability of the North China Craton (from its destruction to its consolidation); (ii) the heterogeneous water content in the Cenozoic lithospheric mantle beneath different blocks of eastern China was not only inherited from tectonic settings from which they came, but was also affected later by geological processes they experienced; (iii) the distinct water content between the lowermost crust and lithospheric mantle of eastern China and its induced rheological contrast at the base of the crust indicate that the continental crust–mantle boundary could behave either in a coupled or decoupled manner beneath different areas and/or at different stages; (iv) the alkali basalts of eastern China demonstrate a heterogeneous distribution of water content in the mantle; local and regional comparisons of the water content between the lithospheric mantle and basalts'' source indicate that the Cenozoic alkali basalts in eastern China were not sourced from the lithospheric mantle. Instead, the inferred high water contents in the mantle sources suggest that the Cenozoic eastern China basalts were likely sourced from the mantle transition zone (MTZ); and (v) both oceanic and continental crusts may carry a certain amount of water back into the deep mantle of eastern China by plate subduction. Such recycled crustal materials have not only created a local water-rich zone, but have also introduced crustal geochemical signatures into the mantle, both accounting for crustal geochemical imprints in the intra-plate magmatic rocks of eastern China. 相似文献
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《Journal of The Franklin Institute》2022,359(12):6142-6172
In order for automated mobile vehicles to navigate in the real world with minimal collision risks, it is necessary for their planning algorithms to consider uncertainties from measurements and environmental disturbances. In this paper, we consider analytical solutions for a conservative approximation of the mutual probability of collision between two robotic vehicles in the presence of such uncertainties. Therein, we present two methods, which we call unitary scaling and principal axes rotation, for decoupling the bivariate integral required for efficient approximation of the probability of collision between two vehicles including orientation effects. We compare the conservatism of these methods analytically and numerically. By closing a control loop through a model predictive guidance scheme, we observe through Monte-Carlo simulations that directly implementing collision avoidance constraints from the conservative approximations remains infeasible for real-time planning. We then propose and implement a convexification approach based on the tightened collision constraints that significantly improves the computational efficiency and robustness of the predictive guidance scheme. 相似文献
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Jie Yuan Zhenyu Yang Chenglong Deng Wout Krijgsman Xiumian Hu Shihu Li Zhongshan Shen Huafeng Qin Wei An Huaiyu He Lin Ding Zhengtang Guo Rixiang Zhu 《国家科学评论(英文版)》2021,8(7)
The India-Asia collision is an outstanding smoking gun in the study of continental collision dynamics. How and when the continental collision occurred remains a long-standing controversy. Here we present two new paleomagnetic data sets from rocks deposited on the distal part of the Indian passive margin, which indicate that the Tethyan Himalaya terrane was situated at a paleolatitude of ∼19.4°S at ∼75 Ma and moved rapidly northward to reach a paleolatitude of ∼13.7°N at ∼61 Ma. This implies that the Tethyan Himalaya terrane rifted from India after ∼75 Ma, generating the North India Sea. We document a new two-stage continental collision, first at ∼61 Ma between the Lhasa and Tethyan Himalaya terranes, and subsequently at ∼53−48 Ma between the Tethyan Himalaya terrane and India, diachronously closing the North India Sea from west to east. Our scenario matches the history of India-Asia convergence rates and reconciles multiple lines of geologic evidence for the collision. 相似文献
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Distributed RISE control for spacecraft formation reconfiguration with collision avoidance 总被引：1，自引：0，他引：1
In this paper, we investigate the distributed formation reconfiguration problem of multiple spacecraft with collision avoidance in the presence of external disturbances. Artificial potential function (APF) based virtual velocity controllers for the spacecraft are firstly constructed, which overcome the local minima problem through introducing auxiliary inputs weighted by bump functions. Then, based on the robust integral of the sign of the error (RISE) control methodology, a distributed continuous asymptotic tracking control protocol is proposed, accomplishing both formation reconfiguration and the collision avoidance among spacecraft and with obstacles. Furthermore, using tools from graph theory, Lyapunov analysis and backstepping technique, we show the stability and collision avoidance performance of the closed-loop multiple spacecraft system. Numerical simulations for a spacecraft formation are finally provided to validate the effectiveness of the proposed algorithm. 相似文献
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Significant left-lateral movement along the Ailao Shan-Red River fault accommodated a substantial amount of the late Eocene to early Miocene India-Asia convergence. However, the activation of this critical strike-slip fault remains poorly understood. Here, we show key seismic evidence for the occurrence of massive lithospheric delamination in southeastern Tibet. Our novel observation of reflected body waves (e.g. P410P and P660P) retrieved from ambient noise interferometry sheds new light on the massive foundered lithosphere currently near the bottom of the mantle transition zone beneath southeastern Tibet. By integrating the novel seismic and pre-existing geochemical observations, we highlight a linkage between massive lithospheric delamination shortly after the onset of hard collision and activation of continental extrusion along the Ailao Shan-Red River fault. This information provides critical insight into the early-stage evolution of the India-Asia collision in southeastern Tibet, which has significant implications for continental collision and its intracontinental response. 相似文献
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基于甘肃黄土高原区12个测站1960-2012年的气象资料,利用标准化降水蒸散指数对该区近53a四季干旱的时空变化特征进行了分析。结果表明：甘肃黄土高原区近53a的四季均呈干旱化趋势,以秋季最为突出,春季次之。经过Mann-Kendall趋势分析法检验,秋旱最显著的地方是兰州、靖远及环县;春旱最明显的地方是崆峒、庆阳和西峰;冬季有变湿的趋向,但未通过显著性水平。空间分布上,甘肃黄土高原区腹部比边缘区发生干旱的频率高,山地比谷地发生干旱的频率高。陇中地区夏旱频发,陇东地区冬旱频繁。干旱变幅最大的地方是研究区西北的乌鞘岭和东北的子午岭。近53a研究区干旱事件发生频次呈增长趋势,近10a来尤为显著。中度干旱发生频次的增长速度比极端干旱事件增长的快,但没有极端干旱事件显著。 相似文献