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福建沿海晚第四纪的地壳运动 总被引:4,自引:0,他引:4
利用地表露头剖面和钻孔剖面资料,阐述了福建沿海晚第四纪地壳运动的特征,指出该地区晚更新世期间发生了幅度较大的下降运动,全新世以来,沿海盆地、平原和海湾继续下降,其余地区则显著上升。福建沿海的盆地、平原和海湾的形成、发育常受到北东和北西向两组断裂的控制。阐明这些地区晚第四纪的地壳运动对于研究断裂的活动性、地震预测预报以及重大工程的区域稳定性评价均有重要意义。 相似文献
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郯庐断裂带赤山段晚更新世以来的活动性 总被引:11,自引:1,他引:11
郯庐断裂带赤山段出露于安徽北部泗县境内,在地震地质填图中,经过槽探揭露、断层陡坎和断错冲沟等微地貌测量、年代样品的采集与测定,获得断层最新活动时代、活动方式、垂直和水平位移量等方面的半定量-定量化参数,表明了它在晚更新世以来的活动特征。 相似文献
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安宁河断裂带北段晚更新世以来的分段活动特征 总被引:4,自引:1,他引:4
本文据断裂带的断层几何形态、组合型式、断错地貌及地震活动资料,讨论了安宁河断裂带北段(西昌-石棉田湾段)在晚更新世以来的活动性状。根据该段活动程度的差异,从南至北将其分为三个活动段,即西昌-冕宁段;冕宁-紫马垮段;紫马垮-田湾段。上述三个活动段除南段具备发生大震背景外,中段和北段分别具有发生强震和中强震的背景。根据断层泥中石英碎屑表面扪描电子显微(SEM)结构特征,讨论了安宁河断裂带北段的运动性质,指出西昌-紫马垮段具粘滑运动方式;紫马垮-麂子坪段具粘滑、蠕滑兼有的运动方式;麂子坪以北至田湾段具以蠕滑为主的运动方式。 相似文献
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依据野外槽探实测的仙女山断裂带和和天阳坪断裂带的地质剖面,通过研究断层堆积与构造岩,新老构造岩变形,断层破裂有其几何特征,断层充填物采样年代鉴定等,获得了两断裂带晚更新世末期活动和古地震的最新证据。 相似文献
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ACTIVE CHARACTERISTICS OF THE SANWEISHAN FAULT IN THE NORTHERN MARGIN OF THE TIBETAN PLATEAU DURING LATE PLEISTOCENE 下载免费PDF全文
The Sanweishan fault is located in the northern margin of the Tibetan plateau. It is a branch of the Altyn Tagh fault zone which extends to the northwest. A detailed study on Late Quaternary activity characteristics of the Sanwei Shan Fault can help understanding the strain distribution of the Altyn Tagh fault zone and regional seismic activity and northward growth of the Tibetan plateau. Previous research on this fault is insufficient and its activity is a controversial issue. Based on satellite images interpretation, field investigations and geological mapping, this study attempts to characterize this feature, especially its activity during Late Quaternary. Trench excavation and sample dating permit to address this issue, including determination of paleoseismic events along this fault.
The results show that the Sanweishan fault is a large-scale active structure. It starts from the Shuangta reservoir in the east, extending southward by Shigongkouzi, Lucaogou, and Shugouzi, terminates south of Xishuigou, with a length of 175km. The fault trends in NEE, dipping SE at angles 50°~70°. It is characterized by left-lateral strike-slip with a component of thrust and local normal faulting. According to the geometry, the fault can be divided into three segments, i.e. Shuangta-Shigongkouzi, Shigongkouzi-Shugouzi and Shugouzi-Xishuigou from east to west, looking like a left-or right-step pattern. Plenty of offset fault landforms appear along the Sanweishan Fault, including ridges, left-lateral strike-slip gullies, fault scarps, and fault grooves. The trench study at the middle and eastern segments of the fault shows its activity during Late Pleistocene, evidenced by displaced strata of this epoch. Identification marks of the paleoearthquakes and sample dating reveal one paleoearthquake that occurred at(40.3±5.2)~(42.1±3.9) ka. 相似文献
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福建晋江金井——深沪湾断陷晚第四纪的地壳变动及海平面变化 总被引:1,自引:0,他引:1
本文根据实际调查资料,探讨了福建晋江金井--深沪湾断陷的地貌、第四纪沉积特征,晚第四纪的断裂- 断块构造活动、地壳变形及区域海平面变化。 相似文献
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野外考察见到亚肯背斜区发育 3级主要地貌面 ,在第 2级和第 1级地貌面 (冲洪积扇 )之下采集了堆积物的热释光样品 ,测年结果分别为距今 3 96~ 4 36万年和 0 78万年 ,区域地貌对比研究认为 ,第 2级地貌面被废弃的时代为距今 4万年至 1 2~ 1 3万年 ,第 1级地貌面被废弃的时代为距今 0 78万年之后。横跨背斜不同部位地貌面的地形剖面表明 ,第 2级地貌面形成以来褶皱隆起高度达 6 0m ,第 1级地貌面褶皱隆起高度为 2 0m。地震反射剖面显示 ,亚肯背斜区滑脱面深度约7km ,由平衡地质剖面法得到第 2和第 1级地貌面形成以来褶皱的缩短量分别为 4 7m和 17 9m。第 2级地貌面形成以来褶皱的隆起和缩短速率分别为 1 5~ 5mm/a和 1 2~ 3 9mm/a,第 1级地貌面形成以来褶皱隆起和缩短速率分别为 2 5 6mm/a和 2 2 9mm/a 相似文献
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ANALYSIS OF EVOLUTION OF THE RIYUESHAN FAULT SINCE LATE PLEISTOCENE USING STRUCTURAL GEOMORPHOLOGY 下载免费PDF全文
The northeastern margin of Tibetan plateau is an active block controlled by the eastern Kunlun fault zone, the Qilian Shan-Haiyuan fault zone, and the Altyn Tagh fault zone. It is the frontier and the sensitive area of neotectonic activity since the Cenozoic. There are widespread folds, thrust faults and stike-slip faults in the northeastern Tibetan plateau produced by the intensive tectonic deformation, indicating that this area is suffering the crustal shortening, left-lateral shear and vertical uplift. The Riyueshan Fault is one of the major faults in the dextral strike-slip faults systems, which lies between the two major large-scale left-lateral strike-slip faults, the Qilian-Haiyuan Fault and the eastern Kunlun Fault. In the process of growing and expanding of the entire Tibetan plateau, the dextral strike-slip faults play an important role in regulating the deformation and transformation between the secondary blocks. In the early Quaternary, because of the northeastward expansion of the northeastern Tibetan plateau, tectonic deformations such as NE-direction extrusion shortening, clockwise rotation, and SEE-direction extrusion occurred in the northeastern margin of the Tibetan plateau, which lead to the left-lateral slip movement of the NWW-trending major regional boundary faults. As the result, the NNW-trending faults which lie between these NWW direction faults are developed. The main geomorphic units developed within the research area are controlled by the Riyueshan Fault, formed due to the northeastward motion of the Tibet block. These geomorphic units could be classified as:Qinghai Lake Basin, Haiyan Basin, Datonghe Basin, Dezhou Basin, and the mountains developed between the basins such as the Datongshan and the Riyueshan. Paleo basins, alluvial fans, multiple levels of terraces are developed at mountain fronts. The climate variation caused the formation of the geomorphic units during the expansion period of the lakes within the northeastern Tibetan plateau. There are two levels of alluvial fans and three levels of fluvial terrace developed in the study area, the sediments of the alluvial fans and fluvial terraces formed by different sources are developed in the same period. The Riyueshan Fault connects with the NNW-trending left-lateral strike-slip north marginal Tuoleshan fault in the north, and obliquely connects with the Lajishan thrust fault in the south. The fault extends for about 180km from north to south, passing through Datonghe, Reshui coal mine, Chaka River, Tuole, Ketu and Xicha, and connecting with the Lajishan thrusts near the Kesuer Basin. The Riyueshan Fault consists of five discontinuous right-step en-echelon sub-fault segments, with a spacing of 2~3km, and pull-apart basins are formed in the stepovers.
The Riyueshan Fault is a secondary fault located in the Qaidam-Qilian active block which is controlled by the major boundary faults, such as the East Kunlun Fault and the Qilian-Haiyuan Fault. Its activity characteristics provide information of the outward expansion of the northeastern margin of Tibet. Tectonic landforms are developed along the Riyueshan Fault. Focusing on the distinct geomorphic deformation since late Pleistocene, the paper obtains the vertical displacement along the fault strike by RTK measurement method. Based on the fault growth-linkage theory, the evolution of the Riyueshan Fault and the related kinetic background are discussed. The following three conclusions are obtained:1)According to the characteristics of development of the three-stage 200km-long steep fault scarp developed in the landforms of the late Pleistocene alluvial fans and terraces, the Riyueshan Fault is divided into five segments, with the most important segment located in the third stepover(CD-3); 2)The three-stage displacement distribution pattern of the Riyueshan Fault reveals that the fault was formed by the growths and connections of multiple secondary faults and is in the second stage of fault growth and connection. With CD-3 as the boundary, the faults on the NW side continue to grow and connect; the fault activity time on the SE side is shorter, and the activity intensity is weaker; 3)The extreme value of the fault displacement distribution curve indicates the location of strain concentration and stress accumulation. With the stepover CD-3 as the boundary, the stress and strain on NW side are mainly concentrated in the middle and fault stepovers. The long-term accumulation range of stress on the SE side is relatively dispersed. The stress state may be related to the counterclockwise rotation inside the block under the compression of regional tectonic stress. 相似文献
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华北平原东部地区晚更新世以来的孢粉序列与气候分期 总被引:14,自引:0,他引:14
本文应用图象识别方法,对华北平原东部地区(宝坻—濮阳)的五口井和一个剖面的孢粉资料进行了研究,将本区晚更新世晚期一全新世地层划分为五个孢粉组合带,七个孢粉组合亚带,共建九个孢粉植物群演化阶段。在此基础上根据植物生态特征,探讨了两万年以来的气候演变,确立了九个气候期,并发现全新世以来气候变化具有八次明显的降温及七次升温过程,存在着二千五百年及千年左右的波动周期 相似文献