Study　on　the　characteristics　of　crust－mantle　transition　zone　in　Western　Yunnan　Province     

胡鸿翔  林中洋  边银菊  王椿镛  朱良保 《地震学报(英文版)》1996,9(4):573-581

Ｓｔｕｄｙｏｎｔｈｅｃｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆｃｒｕｓｔ┐ｍａｎｔｌｅｔｒａｎｓｉｔｉｏｎｚｏｎｅｉｎＷｅｓｔｅｒｎＹｕｎｎａｎＰｒｏｖｉｎｃｅＨＯＮＧ－ＸＩＡＮＧＨＵ（胡鸿翔）ＺＨＯＮＧ－ＹＡＮＧＬＩＮ（林中洋）ＹＩＮ－ＪＵＢＩＡＮ（边银...  相似文献   

Morphological characteristics of the earthquake surface ruptures on Awaji Island, associated with the 1995 Southern Hyogo Prefecture Earthquake   总被引：1，自引：0，他引：1  

Aiming  Ian Shinichi  Uda 《Island Arc》1996,5(1):1-15

Abstract The earthquake surface ruptures on the northern side of Awaji Island accompanying the 1995 Southern Hyogo Prefecture Earthquake in Japan consist of three earthquake surface rupture zones called the Nojima, Matsuho, and Kusumoto Earthquake Surface Rupture Zones. The Nojima Earthquake Surface Rupture Zone is - 18 km long and was formed from Awaji-cho at the northern end of Awaji Island to Ichinomiya-cho. It occurred along the pre-existing Nojima geological fault in the northern segment and as a new fault in the southern segment. The northern segment of the Nojima Earthquake Surface Rupture Zone is composed of some subparallel shear faults showing a right-step en echelon form and many extensional cracks showing a left-step en echelon form. The southern segment consists of some discontinuous surface ruptures which are concentrated in a narrow zone a few tens of meters in width. This surface rupture zone shows a general trend striking north 30°-60° east, and dipping 75°-85° east. The deformational topographies and striations on the fault plane generated during the co-seismic displacement show that the Nojima Earthquake Surface Rupture Zone is a right-lateral strike-slip fault with some reverse component. Displacements measured at many of the outcrops are generally 100-200 em horizontally and 50-100 em vertically in the northern segment and a few em to 20 em both horizontally and vertically in the southern segment. The largest displacements are 180 em horizontally, 130 em vertically, and 215 em in netslip measured at the Hirabayashi fault scarp. The Matsuho Earthquake Surface Rupture Zone striking north 40°-60° west was also found along the coastline trending northwest-southeast in Awaji-cho for ～1 km at the northern end of Awaji Island. The Kusumoto Earthquake Surface Rupture Zone occurred along the pre-existing Kusumoto geological fault for ～ 1.5 km near the northeastern coastline, generally striking north 35°-60° east, dipping 60°-70° west. From the morphological and geomorphological characteristics, the Nojima Earthquake Surface Rupture Zone can be divided into four segments which form a right-step en echelon formation. The geological and geomorphological evidence and the aftershock epicenter distributions show clearly that the distributions and geometry of these four segments are controlled by the pre-existing geological structures.  相似文献   

东北深,浅源地震的相关活动   总被引：1，自引：0，他引：1  

朱兆才 《地震地磁观测与研究》1992,13(4):20-24

本文讨论了东北深、浅源地震在时间上、强度上的相关活动特点,认为东北地震是太平洋板块俯冲与亚欧板块挤压作用的结果。东北深震超前于浅源地震活动,可为浅源地震监测预报提供信息。  相似文献   

中国大陆及邻区大震的远距离相关现象   总被引：2，自引：0，他引：2       下载免费PDF全文

王泽皋  孙佩卿  高景春 《地震工程学报》1993,(3)

本文根据中国大陆及边邻M_(?)≥7.0地震活动的时空特点,讨论了大地震活动的远程关联现象,划分了6个相关地带。根据本文所划分的诸相关地带,可以对所研究地区大地震的活动形势作出大致的估计。  相似文献   

Global synchroneity of a positive carbon isotope excursion at the Cenomanian/Turonian boundary: Validation by calcareous microfossil biostratigraphy of the Yezo Group, Hokkaido, Japan     

Takashi  Hasegawa Tsunemasa  Saito 《Island Arc》1993,2(3):181-191

Abstract Isotopic analyses of organic carbon from the mid-Cretaceous sequence in Hokkaido, Japan, revealed a 2‰ positive excursion of δ¹³C values at the biostratigraphically defined Cenomanian/Turonian (C/T) boundary recognized in the Yezo Group. The planktonic foraminiferal Whiteinella archaeocretacea Zone, which is known to bracket the Cenomanian/Turonian boundary elsewhere in the world, was recognized in the Oyubari area of central Hokkaido based on the distribution of commonly occurring planktonic foraminifera. In the Tappu area of northwestern Hokkaido, where diagnostic planktonic foraminifera are rare but calcareous nannoplankton occur commonly, the interval coeval with the W. archaeocretacea Zone can also be established by recognizing the conjoined last appearance levels of Corollithion kennedyi and Axopodorhabdus albianus, both calcareous nannoplankton species. Carbon isotope profiles exhibit a similar pattern with comparable peaks and troughs occurring in the same stratigraphic position in the sequences. A prominent, positive 2‰ shift of δ¹³C values, here called ‘δ¹³C spike’ occurs in the middle of the W. archaeocretacea Zone in the Oyubari area and just above the conjoined last appearances of the two above-mentioned nannoplankton taxa in the Tappu area. The Cenomanian/Turonian boundary can be drawn just above the peak position of the spike in both sections. The Rock Eval analyses and biomarker analyses of organic carbon indicate that organic carbon subjected to our isotope analyses is of terrestrial origin. Therefore, the observed 2%o shift should reflect changes in the isotopic composition of the atmospheric CO₂. A unique layer composed predominantly of sand-grain sized spumellarian Radiolaria is present immediately above the δ¹³C spike both in the Oyubari and Tappu areas, suggesting an increasing availability of both nutrients and silica in surface waters.  相似文献   

中国大陆及邻区大震的远距离相关现象     

王泽皋  孙佩卿  高景春 《地震工程学报》1993,15(3):81-87

本文根据中国大陆及边邻M_S≥7.0地震活动的时空特点,讨论了大地震活动的远程关联现象,划分了6个相关地带。根据本文所划分的诸相关地带,可以对所研究地区大地震的活动形势作出大致的估计。  相似文献   

改进的约束变密度界面反演策略及其应用          下载免费PDF全文

张盛  张明华  刘玲  乔计花  刘绍飞 《地球物理学报》1954,63(10):3886-3895

计算密度分界面的起伏变化在区域地质构造研究和石油矿产资源勘探中具有重要意义.已有密度界面反演方法更多侧重约束变密度界面反演算法,而对约束信息的准确性、研究区横向密度变化往往考虑不足,影响了最终反演结果的可信度.本文在变密度界面正反演算法基础之上,结合实际需求,提出已知深度信息约束下的变密度界面反演策略.该策略主要包括变密度约束反演算法、已知深度约束信息校验和分区变密度模型三个方面.其中反演算法提供了带已知深度约束信息的密度界面迭代反演方法;约束信息校验用于评估约束信息精度,通过调差降低约束信息的系统误差;在反演过程中引入水平密度分区以应对不同构造背景密度界面模型,提高反演结果的可信度.最后将本策略应用于南海莫霍面深度反演计算中,结果显示借助已知约束信息,利用分区密度模型能够获得更为可信的深度反演结果,验证了该策略的正确性.  相似文献   

论中国东部大型盆地区及邻区地质-地球物理复合尺度解析   总被引：7，自引：3，他引：4  

杨宝俊  张梅生  王璞珺  刘财  孙晓猛  焦新华  单玄龙  孟令顺  刘万崧  许文良  郭华 《地球物理学进展》2002,17(2):317-324

作为对中国东部陆缘地带大型盆地区及邻区地质－地球物理综合研究的部分结果,本文的基本认识：（1）穿过松辽盆地的1孙吴－双辽断裂可能是东倾伯低角度壳内断裂;（2）松辽盆地和渤海湾盆地可能属于“混合型裂谷盆地”;（3）东海盆地台北坳陷处在多期次张性应力场环境中,使在其西部附近产生张性正断层系;（4）欧亚大陆东部新生代区域构造运动总体处于右旋走滑拉张环境,其动力因素包括板块运动和地幔物质运动;（5）研究区莫霍面具有较为复杂的变化;（6）复合尺度研究方法是地质－地球物理综合分析的必要手段。  相似文献   

中国与蒙古之地质   总被引：26，自引：0，他引：26  

李怀坤  陆松年  相振群  周红英  郭虎  宋彪  郑健康  顾瑛 《地学前缘》2006,13(6):0-0

东昆仑中部缝合带清水泉一带发育石榴斜长紫苏麻粒岩、紫苏辉石黑云母石榴子石麻粒岩、石榴二辉斜长麻粒岩和石榴单斜辉石麻粒岩,它们与混合岩化黑云母石榴子石变粒岩、黑云母辉石变粒岩、石墨大理岩、含透辉石透闪石大理岩、透辉石大理岩、黑云斜长角闪岩和片麻岩等高级变质岩系以及纯橄岩、辉橄岩、橄长岩、辉长岩、辉绿岩和玄武岩等共同构成蛇绿混杂岩。麻粒岩相变质作用的温压条件为T=760~880℃,p=830~1200MPa,为高温中高压麻粒岩相变质作用,估算其形成深度为40~45km。麻粒岩相变质作用的SHRIMP锆石U-Pb年龄为(507·7±8·3)Ma。清水泉地区蛇绿岩形成于~520Ma,到~508Ma时俯冲至地下40~45km深处而发生中高压麻粒岩相变质作用,然后发生构造折返而剥露至地表。证实了清水泉高级变质岩和基性—超基性岩片是形成于早—中寒武世的蛇绿混杂岩,标志一个古生代早期的非常重要的板块汇聚边界,这对于进一步研究东昆仑造山带构造演化、乃至中国西部大地构造格局具有非常重要的意义。  相似文献   

青藏高原狮泉河-康西瓦地区 1:100万区域重力调查成果     

耿涛 《物探与化探》2007,31(5):391-398

利用最新取得的区域重力资料,参考航磁、遥感、区域地质资料,对青藏高原狮泉河-康西瓦地区重力场分区、断裂构造体系、构造单元、局部异常、深部构造、成矿远景区(带)等进行了研究.对阿尔金走滑断裂西南端的走向和延伸提出了一些新的看法;讨论了2条重力低值带的成因;推断了班公湖-怒江结合带下部莫霍面隆起的高度,从重力角度提出了对班公湖-怒江结合带的认识;认为青藏块体在拼合后地壳有2个加厚中心;新圈定了一个中、新生代沉积盆地,并进行了初步研究;结合地质、矿产、航磁等资料,初步划分出4个成矿远景区(带).  相似文献