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Eric KIRBY 《《地质学报》英文版》2013,87(Z1):354-355
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Global tectonic significance of the Solomon Islands and Ontong Java Plateau convergent zone 总被引：3，自引：0，他引：3
Oceanic plateaus, areas of anomalously thick oceanic crust, cover about 3% of the Earth's seafloor and are thought to mark the surface location of mantle plume “heads”. Hotspot tracks represent continuing magmatism associated with the remaining plume conduit or “tail”. It is presently controversial whether voluminous and mafic oceanic plateau lithosphere is eventually accreted at subduction zones, and, therefore: (1) influences the eventual composition of continental crust and; (2) is responsible for significantly higher rates of continental growth than growth only by accretion of island arcs. The Ontong Java Plateau (OJP) of the southwestern Pacific Ocean is the largest and thickest oceanic plateau on Earth and the largest plateau currently converging on an island arc (Solomon Islands). For this reason, this convergent zone is a key area for understanding the fate of large and thick plateaus on reaching subduction zones.This volume consists of a series of four papers that summarize the results of joint US–Japan marine geophysical studies in 1995 and 1998 of the Solomon Islands–Ontong Java Plateau convergent zone. Marine geophysical data include single and multi-channel seismic reflection, ocean-bottom seismometer (OBS) refraction, gravity, magnetic, sidescan sonar, and earthquake studies. Objectives of this introductory paper include: (1) review of the significance of oceanic plateaus as potential contributors to continental crust; (2) review of the current theories on the fate of oceanic plateaus at subduction zones; (3) establish the present-day and Neogene tectonic setting of the Solomon Islands–Ontong Java Plateau convergent zone; (4) discuss the controversial sequence and timing of tectonic events surrounding Ontong Java Plateau–Solomon arc convergence; (5) present a series of tectonic reconstructions for the period 20 Ma (early Miocene) to the present-day in support of our proposed timing of major tectonic events affecting the Ontong Java Plateau–Solomon Islands convergent zone; and (6) compare the structural and deformational pattern observed in the Solomon Islands to ancient oceanic plateaus preserved in Precambrian and Phanerozoic orogenic belts. Our main conclusion of this study is that 80% of the crustal thickness of the Ontong Java Plateau is subducted beneath the Solomon island arc; only the uppermost basaltic and sedimentary part of the crust (7 km) is preserved on the overriding plate by subduction–accretion processes. This observation is consistent with the observed imbricate structural style of plateaus and seamount chains preserved in both Precambrian and Phanerozoic orogenic belts. 相似文献
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探讨构造、气候与砾岩的关系对于研究青藏高原隆升的时间和方式具有重要意义。裂变径迹热年代学表明积石山地区于8MaB.P.开始构造变形,与碎屑颗粒裂变径迹结果和生长地层结果一致,而明显早于积石砾岩出现的时间(3.6MaB.P.)。通过区分岩体隆升与地面隆升之间的差别,文章提出一种新的模型,以解释隆升、气候和砾岩之间的关系。积石山岩体于8MaB.P.开始隆升,隆升初期,尽管岩体隆升1500~2000m,但是由于积石山上覆的新生代地层易于剥蚀,在花岗岩基底被剥露到地表之前,地表只有少量隆升或没有隆升。随着沉积地层被剥蚀殆尽,基岩暴露于地表,地面隆升速率加快。约3.6MaB.P.,积石山隆升约200~900m,造成了地形雨和发源于积石山的横向河流的出现,这些横向河流把积石山的花岗岩搬运到盆地中沉积下来,形成积石砾岩。 相似文献
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青藏高原松多地区温木朗蛇绿岩的发现及其地质意义 总被引：4，自引：1，他引：3
在藏南工布江达县松多地区温木朗沟发现了一套蛇绿岩,命名为温木朗蛇绿岩。温木朗蛇绿岩大地构造位置处于中冈底斯板块和南冈底斯板块的交界处。通过详细的野外地质调查和室内岩相学研究,温木朗蛇绿岩露头呈南北向分布,岩石端元包括蛇纹岩、超基性堆晶杂岩、变质辉长岩、变质玄武岩、绿片岩,各端元主要呈断层接触,变形变质较强;在蛇纹岩和变质玄武岩中均发现了花岗质片麻岩,在接触界线处存在冷凝边和烘烤边现象,推测其原岩为斜长花岗岩。温木朗蛇绿岩各端元出露相对齐全,是古特提斯洋壳残留的直接证据,对研究青藏高原古特提斯洋演化及冈底斯板块中部构造演化具有重要意义。 相似文献
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在研究区已发表的渐新统资料的基础上,分析了青藏高原渐新世残留盆地的构造背景、岩石地层序列,并对青藏高原渐新世构造岩相古地理特征进行了讨论,该时期总体地势格局仍为东高西低,塔里木、柴达木、羌塘、可可西里、成都等地区主体表现为大面积的压陷湖盆沉积,冈底斯、喜马拉雅和喀喇昆仑等大面积隆升,沿雅鲁藏布江自东向西的古雅江河形成。渐新世构造岩相古地理的演化特征揭示出该时期青藏高原及邻区构造隆升与沉积响应的耦合关系,划分出2个强隆升期,分别是强隆升期A(34～30Ma)和强隆升期B(25～23Ma)。 相似文献
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Previous studies show that the thick aeolian dust deposits in the Chinese Loess Plateau (CLP) have accumulated since the early Miocene or even late Oligocene. They are considered to provide the best terrestrial record for the onset of Asian interior aridification and the evolutionary history of the Asian Monsoon. However, large variability in the basal ages of aeolian deposits makes the aeolian dust depositional history and the controlling dynamics controversial. Here, we present a preliminary hypothesis for the tectonic controls of aeolian dust deposition in the CLP by connecting the two main uplift events of the Tibetan Plateau and the regional tectonic events with the aeolian dust accumulation history. Regional tectonic events in the Ordos Block (the basement of the CLP) during the late Cenozoic are less recognized as controlling aeolian dust accumulation by sculpting the surface landscape. The stable tectonic environment of the Ordos Block since the late Miocene might have been the main controlling factor that enabled the widespread deposition of the aeolian red clay after ~8 Ma. Here, we hypothesize that because the large-scale monsoon system and central Asian aridity had existed since at least the early Miocene, the accumulation and preservation of aeolian deposits within the CLP are actually largely controlled by the regional tectonic environment and less by climatic factors. 相似文献
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青藏高原形成,演化及动力学研究现状 总被引：4，自引：0，他引：4
青藏高原是当今世界上最高、最大和最年轻的高原。它独特的岩石圈结构和构造演化、强烈的新构造运动和环境变迁,对我国乃至亚洲大陆的自然环境和人文地理产生巨大的影响,是打开全球地球动力学的一把金钥匙,近年来在国际上持续地掀起了研究青藏高原热,青藏高原是我国具有特色和优势的研究领域,本文简要地介绍青藏高原研究进展及主要成就,并对其地球动力学问题进行了讨论。 相似文献
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青藏高原晚新生代的扩展和隆升对周边环境演变产生重大影响,确定扩展和隆升的起始年代是一个重要的科学问题。近年来在六盘山、积石山和祁连山及其相邻盆地的研究表明,青藏高原东北缘晚新生代(5~10MaB.P. 或约8MaB.P. )发生了准同期、影响深远的构造变形,导致了沉积盆地的消亡和山脉的隆起。青藏高原北缘的阿尔金山和东缘的岷山、龙门山及川滇高原也在该时段发生了构造活动的加速和构造隆升。所有这些准同期的事件反映了约8MaB.P. 前后青藏高原向周边的扩展,扩展的方式是通过一系列逆冲断裂、褶皱变形、左旋走滑及其伴随的山脉隆起和盆地消亡而实现的。该时期青藏高原的扩展导致了周边的环境变化,奠定了今日环境的格局。 相似文献
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青藏高原周边地区河流分形特征与地貌、构造活动耦合关系 总被引：3，自引：1，他引：2
青藏高原周边地区的地貌特征与形成演化机制一直是科学界研究的热点。选择青藏高原周边典型地区河流分形特征、地貌特征及构造活动性进行研究,发现喜马拉雅断裂带、龙门山断裂带和阿尔金断裂带控制的区域构造活动性强烈,历史地震记录频繁,大震较多,河流形态与地貌演化特征也非常相似,河流纵剖面变化很快,长波长下凹型,河流坡降比大,地形起伏度大,河流形态变化简单,河流分维值低;青藏高原东北缘构造活动性不强烈,历史地震记录偏低,大震极少,河流纵剖面变化缓慢,近似长波长微振幅上凸型,河流坡降比小,地形起伏度较小,河流形态错综复杂、分维值高;青藏高原东南缘,构造活动性较强烈,历史地震记录频繁,大震较多,但由于该区域平均多年侵蚀速率比较低,同时河流下切深度大,河流纵剖面变化缓慢,也是近似长波长微振幅上凸型,河流坡降比小,河网发育较成熟,河网分维值较高。通过对比发现,降水量的变化对该区域侵蚀速率的影响远小于构造活动性的作用,在分析河网形态特征时可以不考虑降水量空间变化的影响。 相似文献
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青藏高原是新生代以来由于印度板块与欧亚板块碰撞而迅速隆起,平均海拔超过4000 m的高原,是研究碰撞过程和形成演化的理想窗口。有关青藏高原的碰撞过程及印度板块岩石圈北缘界线,至今仍然存在较大争议,这可能主要是由于不同研究方法获得认识的差异性和局限性所导致。基于此,本文利用前人深部结构资料,讨论了高原岩石圈的壳幔构造及物质组成等,并从新的地质视角讨论了班怒带的大地构造属性。通过梳理前人的深部结构资料,认为青藏高原的壳幔岩石圈结构较为复杂,如高原内部岩石圈厚度显著大于周缘地区,中下地壳及上地幔广泛分布着低速高导层,这些特殊的地质地球物理结构是印亚板块碰撞的结果。此外,本文进一步对比分析了班怒带的地质与地球物理结构,揭示该构造带两侧存在显著的差异,认为其是印度岩石圈的北缘,这对于认识青藏高原的形成演化具有重要的意义。 相似文献
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青藏高原东北缘现今构造变动与地震活动特征 总被引：6，自引：2，他引：6
笔者利用青藏高原东北缘20世纪70年代以来的精密水准网和跨断层流动形变网监测资料和近10a来高精度GPS观测结果,结合地质构造和地震活动,研究和探讨了该区现今构造变动和强震活动的一些特征和初步机理。结果表明：①研究区现今构造变动具有空间分布的不均一性和随时间演化的非平稳性,其总体趋势呈现为新构造时期以来的继承性;②构造变动过程中的快速隆升异常区和与之相伴生的高梯度变形带、以及显著地断层活动异常,是较强地震孕育的标志,地震往往发生在具有较高应变积累的区域附近;③印度板块对青藏高原的强烈挤压是该区构造变动与地震活动的主动力环境;构造变动和地震与块体活动及区域构造应力场变化密切相关。 相似文献
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WANG An WANG Guocan LI Dewei XIE Defan LIU Demin Faculty of Earth Sciences China University of Geosciences Wuhan Hubei China State Key Laboratory of Geological Processes Mineral Resources China 《《地质学报》英文版》2009,83(1)
The Hohxil region in the northern Qinghai-Tibet Plateau is occupied by numerous plateau lakes,which have long been inferred as being tectonic products.However,so far little evidence has been found to support this tentative inference.Field survey and morphotectonic analysis of TM satellite images in the eastern segment of the Hohxil region revealed that Kusai Lake and Yelusu Lake are S- shaped pull-apart basins,which were dominated by left strike-slip master faults trending WNW-ESE. The pull-apart distanc... 相似文献
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西藏水热活动区处于印度大陆与亚洲大陆碰撞造山带的关键地带,隶属于地中海—喜马拉雅地热带,水热资源丰富,作为了解地质构造演化、地热系统、气候变化的重要窗口之一,一直是地学界的研究热点。本文利用西藏地区336个温泉水化学数据,采用多种地球化学温标对区域内热储温度进行了评估,揭示了地热异常空间分布规律,并探究其地质环境效应。结果表明:泉口热水温度介于10.12~97.64℃,其中60℃以上占总样本的38.9%;热储温度介于87.12~277.64℃,其中87.12~120℃的占18.7%,在120~200℃的占40.5%,高于200℃的占40.8%,显示区内中高温地热系统分布广泛。高温热储区集中于藏南,有南强北弱特点,并沿着断裂带以"簇丛"状分布,可初略划分为狮泉河—玛旁雍区、措勤—搭格架区、当雄—羊八井—定日带、雅鲁藏布江大拐弯区4个区。温泉密度和高温热储区与SN向的断裂带及地震活动性在空间上有较好的匹配关系。 相似文献
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青藏高原东北缘六盘山地区新生代构造旋转及其意义 总被引：6，自引：2，他引：4
青藏高原东北缘构造变形的研究是认识高原隆起过程、机制和印度-欧亚板块碰撞远程效应的重要途径。新生代时期,海原-六盘山断裂、香山-天景山断裂、烟筒山-窑山断裂和青铜峡-固原断裂控制的青藏高原最东北缘六盘山地区山前盆地群,接受了巨厚的新生代沉积,较完整地记录了高原东北部的变形隆升历史。通过六盘山地区丁家二沟剖面的精细古地磁研究发现,白垩纪结束后至中新世六盘山地区发生了约23°的长期顺时针构造旋转,并主要发生在三个时期:可能于晚始新世至早渐新世六盘山地区发生了约9°的顺时针旋转、早渐新世晚期顺时针快速旋转约9°、早中新世初顺时针快速旋转约5°,同时它们也被地层变形侵蚀和沉积演化所记录,说明印度-欧亚板块碰撞变形的前峰最迟在约始新世末-渐新世初就已经达到六盘山地区。这比目前普遍认同的六盘山地区变形隆升是青藏高原隆起中最晚形成(第四纪以来)的观点早了至少3千多万年,它为深入认识高原隆升过程和环境效应提供了新的证据。 相似文献
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Through a comprehensive study of magnetostratigraphy and sedimentology of several basins in the northeastern Tibetan Plateau, we reveal that the study area mainly experienced six tectonic uplift stages at approximately 52 Ma, 34–30 Ma, 24–20 Ma, 16–12 Ma, 8–6 Ma, and 3.6–2.6 Ma. Comprehensive analyses of pollen assemblages from the Qaidam, Linxia, Xining, and West Jiuquan Basins show that the northeastern Tibetan Plateau has undergone six major changes in vegetation types and climate: 50–40 Ma for the warm-humid forest vegetation, 40–23 Ma for the warm-arid and temperate-arid forest steppe vegetation, 23–18.6 Ma for the warm-humid and temperatehumid forest vegetation, 18.6–8.5 Ma for the warm-humid and cool-humid forest steppe vegetation, 8.6–5 Ma for the temperate sub-humid savanna steppe vegetation, and 5–1.8 Ma for the cold-arid steppe vegetation. Comprehensive comparisons of tectonic uplift events inferred from sedimentary records, climatic changes inferred from pollen, and global climate changes show that in the northeastern Tibetan Plateau the climate in the Paleogene at low altitude was mainly controlled by the global climate change, while that in the Neogene interval with high altitude landscapes of mountains and basins is more controlled by altitude and morphology. 相似文献
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青藏高原主夷平面形成的上限年龄为3.6MaB.P.,临夏盆地新生代湖相沉积同时结束,青藏运动开始,分为A(3.6MaB.P.),B(2.6MaB.P.)和C(1.7MaB.P.)3幕,A幕现代亚洲季风形成,B幕黄土开始堆积,C幕黄河出现;昆黄运动(1.2～0.6MaB.P.)使黄河干流切入青藏高原,大面积山地进入冰冻圈,可能导致中更新世之气候转型;共和运动造成黄河切穿龙羊峡,青海湖孤立,高原达到现代高度.中国三大自然区是高原隆升驱动大气环流改变而导致的中国最高层次的景观分异.本文讨论了8MaB.P.的有限高度隆升及亚洲干旱化的问题,亚洲夏季风22MaB.P.已经开始,是高原隆升及其它因素共同作用的结果,为亚洲古季风阶段.3.6MaB.P.才是现代亚洲季风真正开始的时期,可能北半球进入冰期也与此有密切关系. 相似文献
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青藏高原中段现今构造应力场的数值模拟 总被引：5，自引：0，他引：5
将地壳岩石看成粘性流体,对青藏高原中段进行了构造应力场和速度场的有限元模拟。模拟结果表明:青藏高原总体向北和向东位移,向北的位移速度是南部最大,由南向北逐渐减小;向东的位移速度以唐古拉断裂附近最大,南北两侧逐渐减小,形成"挤出"现象。最大主应力方向在南部以NNW向为主,北部以NNE向为主,总体为近SN向。将模拟结果与构造勘察、地震活动和GPS测量结果进行了对比,它们具有很好的一致性,良好地揭示了青藏高原构造活动规律、断层活动强度和东向位移的驱动机理,青藏高原现今活动是印度板块向北推挤和深部物质东流共同作用的结果。 相似文献
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WU Zhenhan JIANG Wan Peter Blisniuk BI Siwen ZHANG Shukun Olaf Kuchel MAO Yi Institute of Geomechanics CAGS Minzu Xueyuan Nanlu Beijing Institut fur Geowissenschaften Universitat Potsdam Postfach D- Potsdam Germany Liu Xinzhu 《《地质学报》英文版》1999,73(3):289-293
The Shuanghu basin is a NE-trending rift basin bounded by NE-striking normal faults and NW-striking shear-extensional faults of the northern Tibetan Plateau. Four samples from calcite veins in marginal faults and one sample from mudstone (S-3) were collected for dating the evolution of the Shuanghu basin by using the ESR spectrograph of EXM-type. Ages were calculated according to the close-equilibrium model on the basis of the measured ESR signal spectra of samples, providing good chronological information. It is known from the ESR dating that the extensional faulting and rifting of the Shuanghu area began at 4.92 Ma B.P., followed by regional folding in 3.56-1.36 Ma, NW-striking faulting in 0.60 Ma and normal faulting in 0.024 Ma in the Shuanghu basin. 相似文献