流动注射-光度法测定地质样品中痕量碘

利用I~-对4,4′-四甲基二氨基二苯甲烷(4,4′-TMB-DPM)与氯胺T反应的催化作用,建立了流动注射-分光光度测定地质样品中痕量碘的方法。采用不等流速合并带法,分析速度快、节省试剂、灵敏度高。与高温水解法释放I~-相结合,使样品处理简单、干扰离子少。对于含I~-10μg/L的水样,其RSD(n=19)为1.1％,检出限为0.3ng/ml。用于水系沉积物、土壤分析时,含碘1.6×10~(-6)的样品RSD(n=10)为6.1％,检出限为0.08×10~(-6)。测量速度50N/h。     

Fault type analysis along the San Andreas Fault zone: A numerical approach

Finite Element (FE) modeling under plane stress condition is used to analyze the fault type variation with depth along and around the San Andreas Fault (SAF) zone. In this simulation elastic rheology was used and was thought justifiable as the variation in depth from 0.5 km to 20 km was considered. Series of calculations were performed with the variation in domain properties. Three types of models were created based on simple geological map of California, namely, 1) single domain model considering whole California as one homogeneous domain, 2) three domains model including the North American plate, Pacific plate, and SAF zone as separate domains, and 3) Four domains model including the three above plus the Garlock Fault zone. Mohr-Coulomb failure criterion and Byerlee's law were used for the calculation of failure state. All the models were driven by displacement boundary condition imposing the fixed North American plate and Pacific plate motion along N34°W vector up to the northern terminus of SAF and N50°E vector motion for the subducting the Gorda and Juan de Fuca plates. Our simulated results revealed that as the depth increased, the fault types were generally normal, and at shallow depth greater strike slip and some thrust faults were formed. It is concluded that SAF may be terminated as normal fault at depth although the surface expression is clearly strike slip.     

南海东北部洋陆过渡区域地震折射波衰减特征

地震波衰减研究是了解岩石圈构造特征的有效方法.本文基于OBS2016-2测线的海底地震仪(OBS)数据, 首次对南海东北部洋陆过渡区域地震波衰减特征进行研究, 通过正演模拟获得该区域二维纵波衰减(Q_P)结构.结果表明, 下陆坡的上地壳存在一个宽约40 km, 厚度约为4~5 km的高衰减区, 其特征为低纵波和横波速度(V_P为5.5~6.3 km·s^-1和V_S为3.1~3.6 km·s^-1)以及较低的波速比(V_P/V_S为1.72~1.80), 对应较低的Q_P(280~410), 推测与断裂发育有关, 且受到火山活动的影响.洋陆过渡及洋壳区域的上地壳高衰减区具有低Q_P(300~400)和高V_P/V_S(1.90~1.96)特征, 可能对应较多的断裂发育及流体运移.洋陆过渡区域下地壳高速异常体表现为相对低的Q_P(550~600), 对应较高的V_P(7.0~7.8 km·s^-1)和V_S(3.5~3.8 km·s^-1)以及较高的V_P/V_S(1.85~1.96), 推测与蛇纹石化作用有关.蛇纹石化可能进一步增加岩石的孔隙度并导致更多的流体运移, 使得洋陆过渡及洋壳区域存在较高的地震波衰减.Q_P结构有助于我们分析南海大陆边缘的地震波衰减特征, 结合V_P、V_S以及V_P/V_S, 可以更好地了解该区域地质结构和岩石属性, 对进一步挖掘OBS数据信息有重要参考价值.

     

海陆气候事件关联规则挖掘方法

近年来,异常气候事件的频发对人类的生活环境和经济发展带来严重负影响。气象学家研究表明：海洋气候异常对陆地气候异常事件的发生具有重要的诱发作用,因此,对海陆气候间的内在关联机制进行深入挖掘具有重要研究价值。本文提出了一种关联规则挖掘方法,以探索单一海洋气候指数与陆地异常气候事件间存在的关联。首先,针对陆地气候要素,采用顾及空间邻近关系的层次聚类方法进行有效气候分区,通过对各层分区结果进行相关统计分析得到有效的各区域气候序列;然后,进行顾及多重约束进行时序关联规则挖掘,以探索海陆气候要素间的关联机制;最后,通过实际算例分析得到的各气候指数与我国陆地区域异常降水事件间的关联机制结果,与实际情况高度吻合。     

郯庐断裂带中南段重磁特征与深部构造

郯庐断裂带是中国东部地球物理场的分界线。它在磁场上呈现出一条NNE向线性正磁异常带,它的重力场特征表现为规模较大的布格重力异常梯度带。在断裂带的两侧,其区域磁场、区域重力场无论是场值大小,还是异常规模以及各异常的展布形态等诸方面都具有明显的区别。地球物理特征揭示郯庐断裂带深部构造,为研究重点矿产分布规律及地震灾害预报具有重要的实际意义。     

广西东兰某地微粒型金矿地质特征和成因分析

东兰金矿产于中三叠世早期板纳组复理石沉积建造层间破碎硅化蚀变带中。矿体呈层状,似层状和脉状。矿石类型为褐铁矿化破碎硅化砂岩、石英细脉和层状复理石韵律矿石。含金矿物主要为褐铁矿、黄铁矿和有机质。具有层间破碎、碎粒、沉积结构构造特征,属典型成岩—后生型层控矿床。矿床成因与生物礁的消失、碎屑流事件、深水火山碎屑泥质上超盆地靠近天峨孤立碳酸盐台地缓坡深水沉积部位、复理石浊积岩相、印支期天峨背斜东南翼层间破碎硅化蚀变带,以及有机质的热解和分异有关。     

利用GPS资料研究山西裂谷带的水平形变

基于山西及邻近地区的GPS测量资料,给出山西裂谷带水平形变场演化图像,研究山西裂谷带拉张、挤压等受力状况与地震活动之间的关系,探讨预报地震的方法。     

Seismo-tectonic divisions of strong earthquakes with M_s≥7.0 and their tectonic geomorphology along Xianshuihe-Xiaojiang fault zone

IntroductionXianshuihe-Xiaojiang fault zone is an important active fault zone and a strong earthquake belt in the southeastern margin of Qinghai-Tibet Plateau (Figure 1). Since 814 AD a total of 14 earthquakes with M ( 7, including one of magnitude 8.0, took place there. This large-scale fault zone runs from north to south, includes the northwesterly Xianshuihe fault, the near-NS An(ninghe fault, NNW Zemuhe fault, and near-NS Xiaojiang fault. It forms the east boundary of Sichuan-Yunn…