古地震~(14)C年龄的日历年代校正

文中简要概述了古地震14C年龄转换成日历年龄的必要性和树轮校正曲线研究历史以及当前最新研究进展,并介绍了树轮校正方法和相关校正软件,分析了日历年龄区间变宽的原因,这将有助于正确理解14C年龄及其时间标尺的内涵     

长白山天池火山炭化木的~(14)C年代及其意义

对长白山天池火山喷发形成的灰白色空降浮石层、黑色熔结凝灰角砾层和火山碎屑堆积物中 16个炭化木作了系统的14C年龄测定,结果表明天池火山喷发年代为 (1215±15)AD。从火山碎屑堆积中采集的炭化木测定的14C年代要比火山喷发年代偏老,最大可偏离 800a;炭化木树皮的测定结果比较接近火山喷发年代;黑石河、浮石林、锦江大峡谷等地的黑色熔结凝灰角砾层的14C年代结果表明它们也属于(1215±15)AD大喷发的产物     

海原断裂带刺儿沟剖面烘烤次生黄土的光释光测年及其地质意义

选择海原活动断裂带刺儿沟剖面2个烘烤次生黄土样品LEDL0588H和LEDL0365的细颗粒石英,采用改进后的单测片再生法(SAR)和简单多测片再生剂量法(SMAR)进行了一系列实验研究。2个样品细颗粒石英的光释光信号均以快速组分为主,其等效剂量(DE)的预热坪实验表明,在180～260℃的预热温度范围内均能获得基本一致的DE值。SAR法测量不同预热温度下的释光感量变化、剂量恢复实验和LN/TN比值的关系以及SMAR法测量中LN/TN比值与预热温度的关系的研究表明,文中所采用的流程能有效地校正测量过程中释光信号感量变化。2种方法均适用于采自不同层位的2个烘烤样品细颗粒石英的OSL测年,并获得了非常接近的OSL年龄。2个样品最后一次被烘烤的时间可能代表的是同一时期的人类活动     

滨海断裂北带何在——~(14)C测年资料在工程地震中的应用

本文研究了珠海西区三处大型工程场址的资料,结果表明,在珠海西区的近海海城,滨海断裂带并不明显,而北西向西江断裂带的近期活动性却有自西而东增强的趋势,其活动性最强的部位是在磨刀门地区。     

花粉浓缩物的加速器~(14)C年代测定初探

在环境敏感带的风积物、湖积物剖面中采集了 1 7个样品 ,建立了适用于风积物中花粉浓缩物提取的实验方法 .将花粉浓缩物的测年结果与某些已知年代样品作了对比研究 ,进行了花粉浓缩物的加速器14 C测年的初步探索 .结果表明 ,在稳定环境下与沉积物同时沉积的花粉测年具有一定的可信度 .它将为改善黄土高原晚更新世以来年代测定提供一条新的可能途径 .同时 ,将14 C测年与野外地质观察相结合 ,提取了该敏感带晚更新世向早全新世转换过程中 4次主要的季风降水变化的地质记录     

独山子地区荒漠土的￣（14）C年龄测定及意义

通过对独山子地区荒漠土碳酸盐淀积层的￣１４Ｃ年龄测定，探讨了碳酸盐淀积层碳的来源及其￣１４Ｃ年龄的可靠性问题。提出了根据碳酸盐淀积层的无机碳年龄，对确定土壤的年龄是有意义的     

南极格罗夫山地表岩石样品中宇宙成因~(21)Ne的含量及暴露年龄

地表岩石中21Ne和22Ne有多种来源:宇宙成因、原位放射性成因、捕获的地壳源放射性成因和捕获的微量大气.本研究报道了首次在中国开展的对地表石英中宇宙成因21Ne和22Ne的测定工作.我们采用了一个独创的样品前处理方法,有效地去除了石英中的包体,最大限度地减少了放射性成因21Ne和22Ne的贡献.多阶段加热结果表明南极格罗夫山地区哈丁山地表岩石样品R9202和R9203中宇宙成因21Ne和22Ne的含量分别为(3.83±0.87)×108和(5.22±0.51)×108atom·g-1,其相应的最小暴露年龄为(2.2±0.5)和(3.0±0.3)Ma,表明哈丁山顶的暴露至少从上新世中期就已开始.     

沂沭断裂带断层泥中 K-Ar、FT 和 TL 体系年代学含义的初步研究

本文报道了利用K-Ar法、TL法和FT法,分别测定断层泥中1Md伊利石(<1μ粒级组份)、石英(2-10μ粒级组份)和磷灰石单矿物的年龄结果;给出了沂沭断裂带三次强烈活动的年龄区间及强度逐渐减弱的变化趋势。首先提出了利用这三种测年手段,测定断层泥中三种不同物质的年龄,进而研究断层活动(强度和时间)的新方法     

海原走滑断裂带及其尾端挤压构造

研究了青藏高原东北部地区海原活动断裂带的几何学、运动学和动力学特征、左旋位移总量及全新世滑动速率,对海原走滑断裂带东南端发育的尾端挤压区的构造特征及地壳缩短量进行了研究,分析了走滑断裂带的走滑量与端部挤压区地壳缩短量之间的转换平衡关系     

南京长江全新世河流阶地的年代及其意义

河流阶地作为古气候和古环境的重要载体,在研究古气候、古环境变化方面有着极其重要的作用.文中对南京市长江南岸全新世河流阶地的23m厚钻孔沉积物,采用细颗粒石英单测片再生法技术进行了系统的光释光(OSL)测年,并对沉积物中的植物碎片等进行了<‘14>C测年,样品的OSL年龄和经树轮校正后的<‘14>C年龄吻合.测年结果表明...     

六盘山东麓断裂断层泥的组构特征及其意义

本文采用宏观与微观相结合的方法 ,研究六盘山东麓断裂的滑动方式。结果表明 :(1)根据断层泥组构特征 ,六盘山东麓断裂可划分为北、中、南 3段 ,这与前人宏观分段结果相一致 ;(2 )北段断层泥局部强烈变形 ,发育牵引褶皱 ,吕德剪切角 (R1)介于 11°～ 2 6° ,以及伊利石无明显的优选方位组构 ,表明该段断层活动是以粘滑为主的左旋走滑运动 ;(3)中、南段断层泥普遍变形 ,吕德剪切角 (R1)一般小于 11° ,P叶理、带状褶皱和肠状构造发育 ,以及伊利石复杂的优选方位组构 ,显示该断层的活动是以蠕滑为主的多期逆冲滑动     

INTERPRETATION AND ANALYSIS OF THE FINE FAULT GEO-METRY BASED ON HIGH-RESOLUTION DEM DATA DERIVED FROM UAV PHOTOGRAMMETRIC TECHNIQUE: A CASE STUDY OF TANGJIAPO SITE ON THE HAIYUAN FAULT

Fault-related tectonic geomorphologic features are integrated expressions of multiple strong seismological events and long-term surface processes, including crucial information about strong earthquake behavior of a fault. It's of great significance to identify the strong seismic activity information from faulted landscapes, which include the date and sequence of the seismic activities, displacements, active fault features, for studying the seismic rupture process, predicting the future seismic recurrence behavior and evaluating the seismic hazard of the fault. However, due to the restriction of measuring techniques and the subsequent poor quality of the acquired data, it has been difficult to accurately extract such information from complex tectonic landforms to study active faults for a long time. Recently, "small Unmanned Aerial Vehicle(sUAV)" photogrammetric technique based on "Structure from Motion(SfM)" provides a cost-efficient and convenient access to high-resolution and high-accuracy "digital elevation models(DEMs)" of tectonic landforms. This paper selects the Tangjiapo area at the Haiyuan Fault to conduct data collection, in which the structural and geomorphic features are well preserved. Using a small quadrotor unmanned aerial vehicle(Inpire 2), we collect 1598 aerial photographs with a coverage area of 0.72km². For calibrating the accuracy of the aerial data, we set 10 ground control points and use differential-GPS to obtain the spatial coordinates of these control points. We use model software Agisoft PhotoScan to process these digital pictures, obtaining high-resolution and high-accuracy DEM data with the geographic information, in which data resolution is 2.6cm/pix and the average density of point cloud is 89.3 point/m². The data with these accuracy and resolution can fully show the real geomorphic features of the landform and meet the requirements for extracting specific structural geomorphic information on the surface. Through the detailed interpretation of the tectonic landforms, we identify a series of structures associated with the strike-slip fault and divide the alluvial fan into four stages, named s₁, s₂, s₃, and s₄, respectively.Wherein, the s₁ is the latest phase of the alluvial fan, which is in the extension direction of the Haiyuan Fault and there isn't any surface fracture, indicating that the s₁ was formed after the M8.5 Haiyuan earthquake in 1920. The rupture zone on the s₂ fan is composed of varied kinds of faulting geomorphologic landforms, such as a series of en echelon tension-shear fractures trending 270°~285°, fault scarps and seismic ridges caused by the left-lateral motion of the seismic fault. In addition, a number of field ridges on the s₂ fan were faulted by the 1920 Haiyuan M8.5 earthquake, recording the co-seismic displacements of the latest earthquake event. Relatively speaking, the surface rupture structure of the s₃ fan is simple, mainly manifested as linear fault scarp with a trend of 270°~285°, which may indicate that multiple earthquakes have connected the different secondary fractures. And a small part of s₄ fan is distributed in the southwest of the study area without fault crossing. Furthermore, we measured the horizontal displacements of river channels and vertical offsets of fault scarps. The faulted ridge on the s₂ fan and faulted gully on the s₃ fan provide good linear markers for obtaining the fault left-lateral dislocation. We used the graphical dislocation measurement software LaDiCaoz developed based on Matlab to restore the gully position before the earthquake by comparing the gully morphology on both sides of the fault, and then determined the horizontal offset of s₂, which is(4.3±0.4)m and that of s₃ is(8.6±0.6)m. In addition, based on the DEM data, we extracted the fault scarp densely along the fault strike, and obtained the vertical offset of s₂, which is(4.3±0.4)m and that of s₃ is(1.79±0.16)m. Moreover, we detect slope breaks in the fault scarp morphology. For compound fault scarps generated by multiple surface rupture earthquakes, there are multiple inflection points on the slope of the topographic section, and each inflection point represents a surface rupture event. Therefore, the slope break point on the scarp becomes an important symbol of multiple rupture of the fault. The statistical result shows that the slope breaks number of s₂ is 1 and that of s₃ is 2. Based on the analysis of horizontal displacements of river channels and vertical offsets of fault scarps as well as its slope breaks, two surface rupturing events can be confirmed along the Tangjiapo area of the Haiyuan Fault. Among them, the horizontal and vertical displacements of the older event are(4.3±0.95)m and(0.85±0.22)m, respectively, while that of the latest event are(4.3±0.4)m and(0.95±0.14)m, which are the coseismic horizontal and vertical offsets of the 1920 Haiyuan earthquake. These recognitions have improved our cognitive level of the fine structure of seismic surface rupture and ability to recognize paleoearthquake events. Therefore, the high-resolution topographic data obtained from the SfM photogrammetry method can be used for interpretation of fine structure and quantitative analysis of microgeomorphology. With the development of research on tectonic geomorphology and active tectonics toward refinement and quantification, this method will be of higher use value and practical significance.     

云南某工区F1断裂断层物质特征及其意义

断层物质是断层活动的产物,采用多种测试技术从断层物质中必定能提取出与断层活动有关的信息。通过对F_1断裂断层泥中粘土矿物X射线衍射、热释光测年、石英碎砾SEM观测、断层泥显微构造分析等多种方法的综合研究,结果表明,F_1断裂最后一次活动时期在中更新世晚期,活动方式是以粘滑为主,且断层泥形成时温度小于200℃。     

鲜水河断裂带的断错地貌及其地震学意义

断层的近代位错必将在地貌形态上留下深刻的印记,因而凭借断错地貌现象有可能得到关于活断层上地震活动性的重要信息。鲜水河断裂带上的断错地貌现象表明,断层以间歇性的地震滑动为特征,而且服从于大小相当的地震在原地重复发生的特征地震模式。断错水系的演化图象则进一步提供了在一定时段内,同一地点滑动速率基本稳定的线索。于是,可以把断错地貌的研究作为地震活动性研究的重要手段     

海原断裂带西段断层泥的分形研究

利用光学和电子显微镜研究了海原断裂带西段断层泥的粒径分布，５微米至１厘米的粒径段，断层泥具有自相似特征，断层面的粘滑摩擦的特征位移参数可由分维上限（约１厘米）确定。同时用分形理论分析了断层泥粒度分重量百分比的分形结构特征，探讨了粒度成分分维值与断层运动特征的关系。