THE STUDY OF QUATERNARY ACTIVITY OF BAOTOU FAULT IN HETAO ACITVE FAULT SUBSIDENCE ZONE

Existing achievements about Baotou Fault demonstrate it as a buried eastern boundary of the Baiyanhua Basin in Hetao active fault subsidence zone,striking NE.More data is needed to assess its activity.Located in the relay ramp between Wulashan Fault and Daqingshan Fault,Baotou Fault's activity is of great importance to discuss the linkage mode and the response to the earthquake of the adjacent fault.Also it is necessary to the knowledge of the characteristic of the seismic tectonic in local area.Recently it is prevalent to combine shallow seismic profile and composite drilling section to study the activity of the buried fault.Shallow seismic profile indicates that Baotou Fault is a normal fault,inclining to NW.The displacement of the Tg at 75m underground is 25m.Composite drilling section indicates that it is a growth fault,the up-break point of which is 45.6m underground and ends in brownish red clay strata of early Pleistocene.In comparison,the upper Late Pleistocene strata are out of the influences of the tectonic subsidence zone.Baotou Fault's activity is limited to the early Pleistocene.     

GEOMORPHOLOGICAL CHARACTERISTICS OF DAQINGSHAN DRAINAGE AREA IN THE NORTHERN MARGIN OF HETAO BASIN

The Daqingshan Fault located in the northern margin of the Hetao Basin has experienced intensive activity since late Quaternary, which is of great significance to the molding of the present geomorphology. Since basin geomorphological factors can be used to reflect regional geomorphological type and development characteristics, the use of typical geomorphology characteristics indexes may reveal the main factors that control the formation of topography. In recent years, more successful research experience has been accumulated by using hypsometric integral(HI) values and channel steepness index(k_sn)to quantitatively obtain geomorphic parameters to reveal regional tectonic uplift information. The rate of bedrock uplifting can be reflected by channel steepness index, the region with steep gradient has high rate of bedrock uplifting, while the region with slower slope has low rate of bedrock uplifting. The tectonic uplift can shape the geomorphic characteristics by changing the elevation fluctuation of mountains in study area, and then affect the hypsometric integral values distribution trend, thus, the HI value can be used to reflect the intensity of regional tectonic activity, with obvious indicating effect. Knick point can be formed by fault activity, and the information of knick point and its continuous migration to upstream can be recorded along the longitudinal profile of stream. Therefore, it is possible and feasible to obtain the information of tectonic activity from the geomorphic characteristics of Daqinshan area. The research on the quantitative analysis of regional large-scale tectonic activities in the Daqingshan area of the Yellow River in the Hetao Basin is still deficient so far. Taking this area as an example, based on the method of hypsometric integral(HI) and channel steepness index(k_sn), we use the DEM data with 30m resolution and GIS spatial analysis technology to extract the networks of drainage system and seven sub-basins. Then, we calculate the hypsometric integral(HI) values of each sub-basin and fit its spatial distribution characteristics. Finally, we obtain the values of channel steepness index and its fitting spatial distribution characteristics based on the improved Chi-plot bedrock analysis method. Combining the extraction results of geomorphic parameters with the characteristics of fault activity, we attempt to explore the characteristics of drainage system development and the response of stream profile and geomorphology to tectonic activities in the Daqingshan section of the Yellow River Basin. The results show that the values of the hypsometric integral in the Daqingshan drainage area are medium, between 0.5~0.6, and the Strahler curve of each tributary is S-shaped, suggesting that the geomorphological development of the Daqingshan area is in its prime, and the tectonic activity and erosion is strong. Continuous low HI value is found in the tectonic subsidence area on the hanging wall of the Daqingshan Fault. The distribution characteristics of the HI value reveal that the Daqingshan Fault controls the geomorphic difference between basin and mountain. Longitudinal profiles of the river reveal the existence of many knick points. The steepness index of river distributes in high value along the trend of mountain which lies in the tectonic uplift area on the footwall of the Daqingshan Fault. It reflects that the bedrock uplift rate of Daqingshan area is faster. The distribution characteristics of the channel steepness index show that the uplift amplitude of Daqingshan area is strong and the bedrock is rapidly uplifted, which is significantly different from the subsidence amplitude in the depression basin at the south margin of the fault, indicating that the main power source controlling the basin mountain differential movement comes from Daqingshan Fault. Based on the comparison and analysis on tectonic, lithology and climate, there is no obvious corresponding relationship between the difference of rock erosion resistance and the change of geomorphic parameters, and the precipitation has little effect on the geomorphic transformation of Daqingshan area, and its contribution to the geomorphic development is limited. Thus, we think the lithology and rainfall conditions have limited impact on the hypsometric integral, longitudinal profiles of the river and channel steepness index. Lithology maybe has some influences on the channel knick points, while tectonic activity of piedmont faults is the main controlling factor that causes the unbalanced characteristics of the longitudinal profile of the channel and plays a crucial role in the development of the channel knick points. So, tectonic activity of the Daqingshan Fault is the main factor controlling the uplift and geomorphic evolution of the Daqingshan area.     

山西断陷带北部块体构造活动样式及强震构造背景

应用地块构造几何学方法和原理,系统研究了山西断陷带北部构造区地块构造类型、结构和运动特征. 运用断块多米诺模型,通过断裂构造地貌分析对比,系统地讨论了断块变形、断陷盆地伸展运动特点,及其区域分布特征. 分析结果显示：① 以北西向断裂划分,由西向东分为西区段、中区段和东区段,相应的地壳伸展量分别为4.46 km, 2.80 km和1.86 km.。断块平均伸展量约为1 km. 计算结果与实际测量数据大致相同; ② 以恒山断块为界,山西断陷带北部构造区可分为南北两区, 两区地震活动水平不同,分别为M7和6M     

海原、六盘山断裂带至银川断陷第四纪构造应力场分析

利用断层滑动资料反演构造应力张量从而确定出海原、六盘山断裂带至银川断陷的第四纪两期构造应力场 :早更新世末期以前 ,为北东—南西挤压型构造应力场 ,由此造成该地区断裂活动主要以逆断为主 ;早更新世末期至中更新世以后 ,构造应力场发生了调整 ,主压应力方向由早期的北东—南西改变为北东东—南西西 ,应力结构由挤压型转变为走滑型 ,并导致断裂活动由早期的逆断为主变为走滑为主 ,这种应力场格局一直持续至今。研究区现代构造应力场可划分为 :海原断裂带走滑应力区、六盘山逆断 -走滑混合应力区和银川断陷拉张应力区     

牛首山-罗山断裂带的变形特征及其构造意义

牛首山-罗山断裂带是青藏高原东北缘最外侧的一条断裂带,其空间分布、深部结构、运动学特征以及变形机制对研究青藏高原东北角弧形断裂系的形成与演化具有重要意义。文中通过对横穿牛首山-罗山的4条地震反射剖面的解释及断裂带部分地区大比例尺的构造地质填图,发现牛首山-罗山断裂带具有不连续性与分段性。断裂带南段罗山断裂以正花状构造为特征,显示断裂具有右旋走滑性质;中段牛首山东麓断裂可能并不存在,该区以强烈的褶皱变形为特征;北段三关口断裂则以左旋走滑为特征。牛首山-罗山断裂带的这种不连续性和分段性反映了断裂带的不同构造部位在青藏高原向NE方向扩展过程中具有不同的变形样式。     

岷山隆起的构造地貌学研究

岷山隆起为一第四纪强烈抬升区，构成川西高原的西界。岷山隆起的东、西边界分别受岷江断裂与虎牙断裂的控制，为地震活动带，南部向龙门山构造带过渡。岷江断裂北段的第四纪活动始于距今２Ｍａ以前，为一逆走滑断层，观测到的左旋位移量为２．４ｋｍ，左旋滑动速率为１ｍｍ／ａ。岷江断裂控制了沿隆起西界分布的地震活动，包括１９３３年叠溪和１９６０年漳腊地震     

天桥沟-黄羊川活动断裂带的几何学和运动学特征

依据１ ：５０ ０００ 地质填图资料,对天桥沟—黄羊川活动断裂带晚更新世以来的几何学和运动学特征进行了详细的论述．认为该断裂带可分为逆走滑（ 左旋） 的天桥沟断裂段和正走滑（ 左旋） 的黄羊川断裂段,其主要活动时期是晚更新世,滑动速率为４ ～５ ｍ ｍ／ａ ．全新世早期,该断裂带活动强度逐渐减弱,其最后一次活动的时间为距今０ ．７５９ ×１０４ ～１ ．０２ ×１０４ 年     

隆起与拗陷地区地温场的特点

在研究地表热流和5公里深度内区域地温场时,考虑构造形态对地温场的影响是十分重要的。本文采用有限差分法,通过对几组不同导热系数比值和盖层厚度模型的数学模拟,讨论了隆起和拗陷地区地温场的特点,以及岩石导热性变化对地温场影响的程度,为研究一些特殊构造部位局部热异常带形成的原因提供了理论根据。     

隆起与拗陷地区地温场的特点

在研究地表热流和5公里深度内区域地温场时,考虑构造形态对地温场的影响是十分重要的。本文采用有限差分法,通过对几组不同导热系数比值和盖层厚度模型的数学模拟,讨论了隆起和拗陷地区地温场的特点,以及岩石导热性变化对地温场影响的程度,为研究一些特殊构造部位局部热异常带形成的原因提供了理论根据。     

大同－阳原盆地南缘断裂带的晚第四纪分段和构造地貌变异

大同－阳原盆地南缘断裂带是北京西北～山西北部盆－岭区的一条最大的断层。晚第四纪断层崖高度和高度分布型式把断裂带分为西南和东北两个段落。该断裂带在山前带和山麓坡的构造地貌、微地文期演化历史方面存在着明显的分段变异。构造地貌过程的速度和断层习性差异，以及段落边界的重叠断层特征，是构造地貌变异的直接原因     

富蕴地震断裂带的若干定量特征

对富蕴地震断裂带９处不同地段的平板地质测量结果表明：北部引张段地震断裂 带宽约２２０ｍ,断坎平均高０．４ｍ;中部主体走滑段地震断层长达５３５ｍ以上,断层水平位移为１．８￣７．８ｍ断坎高０．４￣１．２ｍ,水平位移与垂直位移之比为５．７￣８．６;南部末端破裂段地震抛掷巨石距离达４０ｍ,地震断层水平位移为０．４￣９．９ｍ,断坎平均高０．２ｍ,末端及副断层水平位移与垂直位移之比高达２５￣２８。     

浑江断裂带及水系的分形特征和构造活动性研究

应用分开有几何学方法对浑江断裂带及水系进行了分形特征研究。计算结果表明，浑江断裂带具有较强的活动性，而且次级NNE向断层比NE和NW向断层活动性更强，结合地震活动属于 质地貌，构造应力场等方面的分析。探讨了该断裂带的活动性及区域新构造运动特征。     

大同－阳原盆地南缘断裂带的晚第四纪分段和构造地貌变异

大同－阳原盆地南缘断裂带是北京西北～山西北部盆－岭区的一条最大的断层。晚第四纪断层崖高度和高度分布型式把断裂带分为西南和东北两个段落。该断裂带在山前带和山麓坡的构造地貌、微地文期演化历史方面存在着明显的分段变异。构造地貌过程的速度和断层习性差异，以及段落边界的重叠断层特征，是构造地貌变异的直接原因。     

东营凹陷陡坡带油井前兆异常及其动力学成因讨论

分析了东营凹陷陡坡带断裂体系 ,研究了东营凹陷陡坡带油井前兆异常与地震活动的关系 ,探讨了油井前兆异常的动力学成因。孕震过程是应力场变化和调整的过程 ,应力场变化导致孔隙压力变化 ,使得油井产生前兆异常。特定的地质环境是油井前兆异常的基础 ,应力转化为孔隙压力是油井前兆异常的前提。油井前兆异常是正异常还是负异常 ,取决于油井所处的地质环境在孕震过程中地应力是增加还是减小 ,前兆异常幅度取决于孔隙压力的变化幅度     

1996年包头6.4级地震的地壳应变特征

根据GPS观测资料求出的水平地应变和由跨断层垂直形变计算出的速率强度累积率,研究了包头-大同地区1992～1995年、1995～1996年和1996～1999年的各时期的应变特征,并对包头6.4级(1996年5月3)地震前后的地应变进行对比,认为以压应变为主导的高值区可能是未来强震孕育的地区．面应变、主压应变、剪应变和趋势累积率同时较高的地区,强震危险性较大．一般低应变区和张应变为主导的地区,孕育强震的可能性小,属于比较稳定的地区．1992～1999年包头-大同地区的GPS水平应变的演变,反映了1996～1998年地震幕的孕育发展及结束的全过程．以压应变为主的高应变区和应变梯度带可作为未来强震危险区的判定标志之一．     

昌马断裂带滑坡之研究

本文根据大量的野外地质调查资料和人工探槽资科,以及14C年代数据,讨论了昌马断裂带滑坡产生的原因及其形成年代等问题。     

大青山山前活动断裂带分段与潜在震源区划分

潜在震源区的划分主要包括潜在震源区范围的划定以及震级上限的确定,目前遵循地震构造类比和地震活动重复等原则。而活断层的分段特性也是潜在震源区划分时必须考虑的一个重要因素。大青山山前断裂带至今有3种不同的分段方案,文中比较分析了前人对大青山山前断裂带的分段,并在此基础上对大青山及山前盆地的潜在震源区作了新的划分。鄂尔多斯块体周缘被拉张性断陷盆地围绕,这些断裂系地震构造相似,且除呼包盆地外均有历史8级以上地震记录。文中将大青山山前断裂带与鄂尔多斯块体周缘断裂系进行了构造对比,特别是与华山山前断裂进行了断裂活动性定量对比,得出雪海沟到土左旗段的震级上限为8级,断裂两端潜源震级上限均为7.5级     

青海热水-日月山断裂带的新活动特征

热水 -日月山断裂带是发育在青藏高原东北缘柴达木 -祁连活动地块内部的 1条重要的NNW向逆 -右旋走滑活动断裂带 ,长约 183km。断裂由 4条不连续的次级断裂段右阶羽列而成 ,阶距 2～ 3km左右 ,在不连续部位形成拉分区。主断裂两端则形成帚状分叉。断裂活动形成了一系列山脊、冲沟和阶地等右旋断错微地貌 ,其中Ⅰ级阶地右旋断错约 8～ 11m ,Ⅱ级阶地右旋断错约 35m。同时沿断裂带还形成了许多断层陡坎 ,Ⅰ级阶地或洪积台地上断层陡坎高约 0 .5～ 1m ,最高达 2 .8m ,Ⅱ级阶地或台地上的断层陡坎高约 2 .5～ 3m ,最高达 4～ 5m。根据相应的阶地年代 ,计算得到断裂带全新世以来的平均水平滑动速率为 3 16mm/a ,垂直滑动速率为 0 .83mm/a     

莲花山断裂带东南段碧甲地区地震地质特征

在对拟建的惠州钢铁厂址及平海、碧甲地区进行地震地质调查的基础上,论述了莲花山断裂带东南段在稔平半岛的展布方向、发育和组合规律以及(车免)近期以来的活动性,进而对该地区的地震危险性作出评估。     

河套断陷带主要活动断裂最新地表破裂事件与历史大地震

对于历史记录的公元849年大地震的发震构造尚存在一定争议,公元前7年大地震是否发生在河套断陷带,也没有得到确认。通过影像解译、野外地质地貌调查和探槽开挖,结合14C和单颗粒OSL测年,利用构造地貌分析及古地震手段,对大青山山前断裂、乌拉山山前断裂及狼山山前断裂的最新破裂事件进行了对比研究。为了尽可能降低古地震定年的不确定性,采取了序列采样、重点层位多采样等措施。结合以往研究成果认为,大青山山前断裂应为公元849年大地震的发震构造,而狼山山前断裂最近1次地震破裂事件可能与公元前7年大地震有关。