忻定盆地晚更新世晚期的一次构造运动

忻定盆地是山西地堑系北部的一个张性断陷盆地,第四纪构造运动活跃。野外调查表明,盆地内晚更新世晚期经历了一次较强的构造运动,它使得断块山地进一步抬升,中止了末次冰期鼎盛期的一次河流加积过程,位于断裂上升盘的洪积扇扇顶部分也被抬升为洪积台地,山前形成了十几米到几十米的断层陡崖;构造运动还导致断层上升盘河流下切,形成了Ⅱ级阶地。黄土-古土壤时间标尺和多种方式的测年结果表明这次构造运动开始于距今2万年左右     

Geomorphology of the Urümqi River Valley and the uplift of the Tianshan Mountains in Quaternary

The Shaerqiaoke Gravel, more than 400 m in thickness, on the north piedmont of the Tianshan Mountains, is located at the exit of the Urümqi River Valley and belongs to the Molasse construction of the Tianshan Mountains. Another uplift event with the tectonic boundary expansion ended the deposition of the Shaerqiaoke Gravel, and resulted in folding, faulting and down-erosion in the frontier of the deposit. The ESR dating indicates that the top of the Shaerqiaoke Gravel accumulated before 1148 kaBP, probably responding to the Kunlun-Huanghe movement of the Qinghai-Tibetan plateau. After that time, erosion-deposition cycle occurred and 9 terraces developed. The TL and ESR dating techniques were employed to date these terraces, and the results indicate that Terrace 3 was formed at MIS 6. Terrace 2 at Houxia also developed simultaneously. Terraces 5 and 6 were accumulated in 338 kaBP and 562-591 kaBP, respectively. The oldest glaciation, named Gao Wangfeng, correlates to MIS 12.     

The history of crustal uplift and metamorphic evolution of Panzhihua-Xichang micro-palaeoland,SW China: Constraints on Sm-Nd, <Superscript>40</Superscript>Ar/<Superscript>39</Superscript>Ar and FT ages of granulites

Panzhihua-Xichang micro-palaeoland (Panxi ter-rane) is located on the western margin of the Yangtze Block. The western boundary of the Panxi mi-cro-palaeoland, and also the western boundary of the Yangtze Block, is the Jinhe-Jinghe fault, which defines the eastern boundary of the Songpan-Ganzi Fold Belt. The eastern boundary of this micro-palaeoland is the Ganluo fault. On the east side of the Ganluo fault is the Sichuan Basin in the Yangtze Block (fig. 1). Panxi micro-palaeoland is on…     

山西临汾震区地壳上地幔构造的研究

利用郑州－临汾－靖边深地震测深剖面临汾，阳城炮点所获得的太行山至靖边段的观测资料，在以往解释的基础上重新进行了对比解释。研究结果表明：临汾与其东西两侧壳幔结构与构造的差异是极其明显的，其主要特征如下：（１）对仅在临汾以西出现的强震相Ｐ２进行了解释，并在ＰＭ波之前识别出一组来自下地壳的反射波Ｐ５；（２）根据临汾以西Ｐｇ与Ｐ２波的特征，我们确认在临汾盆地下方及其西侧，中地壳的上部８－１２ｋｍ深度内存在     

Primary study on pattern of general circulation of atmosphere before uplift of the Tibetan Plateau in eastern Asia

The Tibetan Plateau is a key factor for the pattern of the general circulation of the atmosphere (GCA) in eastern Asia. The pattern of the GCA after the uplift of the plateau is well known, while the pattern of the GCA before the uplift of the plateau is lack of direct evidences. Based on the knowability of desert, a section recording wind directions across the Cretaceous northern hemisphere mid-low latitude desert belt is measured and the pattern of the GCA in the Cretaceous is revealed. The result shows that the eastern Asia was really controlled by the planetary circulation before the uplift of the plateau, i.e. westerlies in the north and northeast trades in the south. The convert belt between westerlies and trades had drifted northwards and southwards. The possibility of existence of paleo-monsoon is also dealt with and a possibly imposed paleo-monsoon is suggested.     

Monazite age spectra in the Late Cenozoic strata of the Changjiang delta and its implication on the Changjiang run-through time

Uplift of the Tibetan Plateau, inversion of eastern and western geomorphology, eastward flowing of large rivers, and run-through of the Changjiang River exert great influence on sedimentation and environ-mental variations in the East China Sea. Provenance discrimination of Tibetan-Plateau-originated sediments in the river-mouth areas and marginal seas is key to figure out these issues.In the past, most studies of the run-through time of the Changjiang and the Yellow rivers focused on geomo…     

东天山地区风化矿物黄钾铁矾的K-Ar测年及其环境意义

东天山地区金属硫化物矿床氧化带中黄钾铁矾的测年结果显示,红山铜金矿样品08XJ-20的K-Ar年龄为11Ma,延东铜矿、沙泉子铜矿、梅岭铜金矿及马头滩金矿样品的K-Ar年龄都在56～66Ma之间,个别样品如梅岭铜金矿和图拉尔根铜镍矿样品的K-Ar年龄分别为114Ma和194Ma。其中红山铜金矿样品08XJ-20没有其它的含钾且年龄较老的风化残留矿物成分(主要是伊利石、微斜长石、斜长石和石英)的影响,其年龄值11Ma是东天山氧化带表生矿物黄钾铁矾的形成年龄,代表了东天山地区气候向极端干旱转变的时间。这与亚洲大陆西北季风加强,黄土大面积沉积以及青藏高原在垂向上强烈隆升和在横向上向北、东北方向扩展的时间基本一致,从而支持了青藏高原在约8MaBP强烈隆升了约1～2km,并向周边扩展,同时引起大气环流改变的理论模型     

阿尔金断裂带西段莫勒切河河口阶地的构造及气候意义

通过对阿尔金断裂带西段莫勒切河河口附近卫星影像解译、野外调查测量及地貌面样品年龄测定,利用宽谷阶地、堆积阶地获取构造隆升速率、构造变形方式及加积速率,并结合区域气候资料探讨该区阶地发育对气候变化的响应.莫勒切河出山口发育4级阶地(T<‘4>,T<‘3>,T<‘2>,T<‘1>),其中T<‘4>、T<‘3>为宽谷阶地,T...     

中国大陆活动地块边界带主要断层的强震震间晚期综合判定

由于中国大陆强震主要分布在活动地块边界带上,所以活动地块边界带主要断层成为我国大陆型强震研究的重要目标,各强震孕育阶段的判定是大陆型强震原地复发的动力学过程研究主要内容,而目标断层是否处于震间晚期也是强震时间预测的重要研究基础.虽然地震短临预测仍存在诸多科学难题,但最近20年来全球若干强震相关研究表明,如果放宽预测时间尺度的要求,有些方法也可用于强震震间晚期的判定.本文以中国大陆活动地块边界带的391条断层段为研究目标,利用地震地质的强震破裂空段、大地测量的断层运动闭锁段、地震活动的中小地震稀疏段、数值模拟的库仑应力增强显著段等方法,综合判定中国大陆活动地块边界带可能处于震间晚期的主要断层段.本文结果仅是初步结果,该结果的可靠程度有赖于监测条件,其科学性有赖于大陆型强震孕育发生动力学过程的认识水平,虽然本文尝试给出中国大陆活动地块边界带主要断层的震间晚期判定结果,但其结果可靠程度、精细程度等均存在巨大的改善空间.最后,从断层孕震阶段判定需求的角度,本文尝试给出大陆型震源物理模型的具体基础模型,期望起到抛砖引玉的作用,也期望更多地震学家关注大陆型强震的物理机制及其预测基础研究.

     

亚失稳准动态及同震过程变形场时空演化特征 ——实验与分析

断层亚失稳模型指出,在临震亚失稳阶段中各种物理量存在规律性的时空演化特征,控制这些物理参数变化的根本原因是震源的力学过程.为深入观测和分析该过程,文中介绍了一套自主研发的64通道、16位分辨率、4MHz采样频率、可并行连续采集的超动态变形场观测系统(Ultra-HiDAM),首次实现了在4MHz频率下对应变信号和声发射...     

水系分维的构造含义

本文运用分数维几何学,研究了河流水系分维与地壳里向运动、活动断裂格局及运动学特征的关联性。结果表明:1)地壳垂向运动控制大型河流主干的总体形态;2)活动断裂格局复杂、水平运动强烈的地区,水系分维值高;3)走滑断裂较斜滑断裂对水系发育的控制强烈,而后者主要起到对水系的分区作用。     

结合欧拉矢量的反演算法构建青藏高原东北缘地壳运动速度场模型

探讨地壳运动速度场模型的构建方法,提出结合欧拉矢量的维多样性动态权重粒子群算法构建地壳运动速度场模型。通过模拟算例验证该算法的稳定性和有效性,建立的速度场模型与线性权重粒子群算法和非线性权重粒子群算法的计算结果相比具有较高的精度,且收敛速度较快。利用青藏高原东北缘1999—2013年中国地壳运动观测网络观测到的GPS水平速率结果,在块体划分和模型辨识的基础上,建立青藏高原东北缘地壳运动速度场模型,并将其与最小二乘配置法的计算结果进行比较,结果表明改进的粒子群算法建立的地壳运动速度场模型具有较高的精度。     

Regional tectonic deformation setting before the Ms8.1 earthquake in the west of the Kunlun Mountains Pass

This paper gives a preliminarily study of the regional tectonic deformation setting before the Ms8.1 earthquake that occurred in the west of the Kunlun Mountains Pass; in the study, the data of the velocity field of crustal horizontal movement during 1991-2000 observed by GPS in and around the Qinghai-Tibet block and those of gravity reiteration in 1998 and 2000 were used. Analysis shows that the preparation and occurrence of this large earthquake are related to the horizontal movement and deformation setting in a large region and might be attributed to the block activity on a relatively large scale. Within the Qinghai-Tibet block, the region of left-lateral shear deformation is of a very large extent. This large earthquake occurred right in such a place where the left-lateral shear strain along the fault strike had the highest rate and the planar dilatation strain was tensile, which was on the margin of negative value region of abnormal gravity variation. The regional tectonic deformation setting can help the huge left-lateral strike-slip rupture to develop.     

中国青藏高原地球物理研究的第一批重大成果其发展导向与核心科学问题的认识和思考

青藏高原的地球物理研究是深化认识高原本体和东亚壳、幔结构、隆升机制与大陆动力学响应的基础,故为中、外地球科学家们所瞩目.为此本文主要讨论以下4个方面问题:(1)问题的提出与背景;(2)率先进行青藏高原深部地球物理研究取得的第一批重要成果与进程;(3)青藏高原地球物理研究中的开创性研究成果和得到的启迪与国际影响;(4)当今青藏高原地球物理研究中的核心科学问题与当前青藏高原地球物理学要做些什么与思考.研究结果表明:(1)在青藏高原地球物理研究中只有在清晰思路指导下,取得高分辨率的数据才能反演,并刻画其壳、幔介质的精细结构;(2)青藏高原地壳巨厚、岩石圈相对较薄的层块结构与壳、幔结构分区特征,特别是存在地壳低速层和地幔低速层及其不均匀展布;(3)在多维力系作用下、深部物质重新分展、调整、运移和在多要素约束下的物理-数学模拟及陆-陆碰撞动力学响应;(4)当今在青藏高原地球物理研究的核心问题是地球内部物质和能量的交换、圈层耦合及其深层动力过程.中国地球科学家们应当清晰地认识到,青藏高原地球物理研究乃是中国地球科学家摘取"桂冠"的一个契机,故必须走自主创新之路,以建立起具有特色中国地球科学的理论和和运动学与与学模型.     

CHANGES IN FAULT MOVEMENT PROPERTY AND GENETIC MECHANISM ON THE WESTERN SEGMENT OF THE XIANGSHAN-TIANJINGSHAN FAULT ZONE

The Xiangshan-Tianjingshan fault zone is an important part of the arc tectonic zone in northeastern Tibet, whose eastern segment is characterized by primarily left-lateral slip along with thrust component. In contrast, the fault movement property on the western segment of the Xiangshan-Tianjingshan fault zone is more complicated. According to the offset geomorphic features and cross sections revealed by the trenches and outcrops, the western segment is mainly a left-lateral strike-slip fault with normal component, and only accompanied with reverse component at specific positions. To determine the genetic mechanism of fault movement property on the western segment, we obtained three main factors based on the integrated analysis of fault geometry:(1)Step-overs:the left-stepping parallel faults in a sinistral shear zone create extensional step-overs and control the nearby and internal fault movement property; (2)terminal structures:they are conductive to stop rupture propagation and produce compressive deformation at the end of the fault trace; and(3)double bends:strike-slip faults have trace that bends such that slip between two adjacent blocks creates a compressive stress and thrust fault. Additionally, the Tianjingshan sub-block moves to SEE and creates an extensional stress at the end of the sub-block associated with normal faults. It shows that the Xiangshan-Tianjingshan fault zone has a complex evolution history, which is divided into two distinctive periods and characterized by laterally westward propagating.     

强震前地震时空相关特征研究

首先,基于强震前地震活动时间变异系数与b值之间具有相关性,对我国四十次6.5级以上强震震例的震前地震活动时空相关特征作讨论。其次,尝试利用相关过程中"第一阶段"的特性来预测未来强震三要素,给出了预测时间、震级的经验公式。最后,对相关过程"第一阶段"判定的可靠性进行了讨论。     

青藏高原东北缘祁连山中部精细地壳结构研究

现今的青藏高原东北缘祁连山地区是在早古生代构造格架的基础之上,于新生代在欧亚大陆与印度大陆碰撞拼合的远程影响下,重新活化进而隆起成为高原的组成部分.因此,该区域地壳结构的揭示不仅可以获得高原地壳变形方式的关键信息,而且也能对该区域早古生代晚期北祁连洋闭合时的相关构造演化提供重要证据.本文以一条穿过青藏高原东北缘祁连山中部地区的深地震反射剖面为基础,结合前人地质、地球物理资料,通过细致的地质构造解译,获得了青藏高原东北缘祁连山中部地区的精细地壳结构.反射剖面图像揭示了海原断裂西段的深部延伸形态、中地壳的双重构造、以及中下地壳的祁连逆冲断裂系等精细的深部构造.结合前人的地质以及地球物理资料,我们提出早古生代晚期北祁连闭合时的南向俯冲以及新生代以来祁连山地区两次陆内俯冲作用可能造就了现今的祁连山.

     

省级GPS基准网建设的启示与思考

以福建省地壳运动观测网络为基础,简要说明了在省级GPS基准网建设过程中项目的立项问题,并对省级GPS基准网的选址、基建、仪器选型与安装调试、数据处理等进行了说明。还对省级GPS基准网的应用需求和发展前景进行了阐述,对其他省局建设省级区域性GPS基准网有所借鉴。     

用地震定位的方法研究1999年9月21日台湾省集集地震的破裂过程

综合分析了福建数字地震台网的记录特征,认为台湾省集集地震具有多重破裂的特征.根据Pn震相的走时方程构造出双曲线方程组,利用福建台网记录到的Pn波段震相的到时资料,测定了9.21台湾省集集地震8个破裂点的震中位置.结果表明,集集地震的最初破裂点位于23.94°N,120.77°E;接着破裂向初始破裂点的南北两侧扩展,且北侧的振幅大,整个过程至少持续了20 s;这8个破裂点的位置几乎成一直线排列,其方向与该区地块的运动方向相近.     

Simulation of individual particle movement in a gravel streambed

A two‐dimensional simulation model of travel distances of individual particles in a gravel‐bed river is presented. The model is based on a number of rules, which include particle size, entrainment, trajectory, distance of movement and entrapment. Particle interactions are controlled by resistance fields defined about each obstacle and critical elevation defined in the model. Resistance fields, particle dropping and critical elevation rules control particle interactions. The interaction rules cause the particles to develop pebble clusters, stone cells and transverse structures (transverse ribs). The simulated travel distances of individual particles are consistent with reported field results. Individual particle travel distances were simulated using two different models; one without interactions between the individual particles and the stationary bed and one with interactions. The case without interactions demonstrates the random nature of sediment transport, and narrow ranges of travel distances. Wider ranges of travel distances, similar to those for natural situations, were obtained for the cases with interactions. The more intense the interaction between the mobile stones and the stationary ones, the wider the range of distances of travel for a given particle size. Modelling the mean travel distance yielded a result similar to that published previously, which was based on empirical data. Well developed bed‐surface structures were obtained for relatively poorly sorted sediment with intense interactions between particles. Transverse structures developed when relatively large particles were allowed to move. Copyright © 2002 John Wiley & Sons, Ltd.