2-D viscoelastic FEM simulation on stress state in the deep part of a subducted slab     

刘亚静  叶国扬  毛兴华  宁杰远 《地震学报(英文版)》2002,15(3):301-308

Introduction It is found that there are some relationships between the thermal structures of subduction zones and the deep seismicity, while the mechanism relates the thermal structure and the deep seismicity is still unsure (Helffrich, Brodholt, 1991; Furukawa, 1994; Kirby, et al, 1996). From 1980s, geoscientists have constituted a series of numerical simulations on the stress states of subduction slabs. Based on the kinetic computation of Sung and Burns (1976a, b), Goto, et al (1983, 1987…  相似文献   

Study on dynamics of tectonic evolution in the Fushun Basin, Northeast China   总被引：1，自引：0，他引：1  

吴冲龙  汪新庆  刘刚  李绍虎  毛小平  李星 《中国科学D辑(英文版)》2002,45(4):311-324

The updated study shows that the taphrogenesis of basement of the Fushun Basin is not a kind of instantaneous process. It intensified gradually and went to extreme in the sedimentary stage of the Guchengzi formation, and then, it weakened rapidly and stopped soon afterwards; the depression did not take place after the taphrogenesis. On the contrary, it almost happened simultaneously with the taphrogenesis. The depression went at a high speed from the beginning of the sedimentary period of the Xilutian formation, and then weakened gradually in the sedimentary period of the Gengjiajie formation. The evolution course of the synsedimentary structure of the Fushun Basin can be summarized as the following six stages: slow taphrogenesis and high speed depression to accelerated taphrogenesis and high speed depression to high speed taphrogenesis and high speed depression to retarded taphrogenesis and high speed depression to gradual halt of taphrogenesis and reduced depression to slow depression and gradual halt of depression. The tectonic evolution resulted in the formation of the "lower taphrogenesis and upper depression" structure. The formation of the binary structure might be due to the suspension of taphrogenesis and the change of the regional structure stress field, but the depression kept going. The result of calculation combining the analysis of the synsedimentary structural frame, the back-stripping method of the subsidence history of the basin basement and the simulation of thermo-settlement history indicates that the great sedimentary space required by the "upper depression part" consists of two parts, namely, 40% from compaction of sediments and 60% from slow depression of the basin basement during a long period of time. Gradual halt of the depression in the Fushun Basin may be attributed to the reversal of the lithosphere hot-recession and gravity isostasy adjustment which may be the result of new hot-events in the depths and accompanied invasion of extremely thick diabase sill, thus revealing a new forming mechanism of "fault subsidence at the base and depression on the top" structure.  相似文献   

大姚地热动态特征分析   总被引：3，自引：1，他引：3  

毛德培  王树明  胡智文  万登堡  石绍先 《地震研究》2002,25(1):42-47

通过大姚高精度水温观测井水地质、井孔条件的分析，震例观测资料、实验观测数据的处理，以及井水水质分析结果，表明大姚水温周期性变化的突出位置是井深75m左右，根本原因是该地层石膏脉稳定释热，含水层热水与井内冷水混合过程中，在通道内形成钙盐类沉淀物（如CaSO4CaCO3），堵塞对流通道，含水层内外压差突破被阻塞通道，热水反复侵入井内，便形成水温周期性变化。地震的孕育、发生和调整过程，由于应力场作用，产生附加地热场，水温基值发生变化，周期畸变或消失，这种附加地热动态是可以恢复的。所以认为大姚地热动态是井区特殊地层地热信息的反映。  相似文献   

对天然地基承载力计算公式的理解和应用   总被引：1，自引：0，他引：1  

毛群芳  徐四一 《上海国土资源》2003,(3):26-29

文章就新老国标和上海标准对地基承载力的计算公式进行了分析比较,并认为在上海地区岩土工程勘察报告中提供天然地基承载力设计值fd更适合。  相似文献   

甘肃北山地区成矿带划分及基本特征   总被引：7，自引：2，他引：7       下载免费PDF全文

张发荣  牛卯胜 《甘肃地质》2003,12(1):50-57

根据成矿地质背景和成矿在时空上的联系性 ,以板块构造单元为基础 ,结合地质、物探、化探、遥感等成矿信息 ,将甘肃北山成矿区带厘定为 2个Ⅱ级成矿区 ,3个Ⅲ级成矿带 ,1 0个Ⅳ级成矿带。以期为矿产勘查和地质大调查工作部署提供新的思路和依据  相似文献   

Geology and Genesis of the Ta'ergou Skarn - Quartz Vein Tungsten Deposit in the North Qilian Caledonian Orogenic Belt, Northwest China     

Zuoheng Zhang    Jingwen Mao    Jianmin Yang    Zhiliang Wang  Zhaochong Zhang 《Resource Geology》2003,53(2):101-114

Abstract. The Ta'ergou tungsten deposit in Gansu province, northwestern China, is located in the western part of the North Qilian Caledonian orogen, and consists of scheelite skarn bodies and wolframite quartz veins. The tungsten‐bearing skarn developed by the replacement of carbonate layers intercalated in the Precambrian schist and amphibolite whereas wolframite‐quartz ore veins developed along a group of fractures that cut through horizontal skarns. The Ta'ergou tungsten deposit is genetically related to the Caledonian Yeniutan granodiorite intrusion and occurs ca. 500 m wide in the exo‐contact zone 300 ～ 500 m apart from the intrusion. The granodiorite displays a lower grade of differentiation, low content of SiO₂ and high contents of mafic components. There are three types of fluid inclusions in the wolframite‐quartz vein systems, i. e. aqueous, CO₂‐H₂O and CO₂‐rich. The homogenization temperature of aqueous inclusion ranges from 140 to 380d?C and their salinities from 6.4 to 17.4 equivalent wt% NaCl. Laser Raman spectroscopy shows that the inclusions contain a relatively high content of CO₂. The δ³⁴S values of skarn type sulfides range from +8.1 to +12.7 per mil and those of quartz vein sulfides from +9.3 to +14.9 per mil, similar to sulfides of the granodiorite with from +6.0 to +11.7 per mil. The δ¹⁸O values of quartz are between +10.5 and +13.3 per mil and those of wolframite between +3.4 and +5.1 per mil. The δ¹⁸O water values of ore forming fluids range from +0.6 to +6.4 per mil and suggest the mixture of magmatic fluids with meteoric water formed the ore‐forming fluids. It has been proved that Precambrian strata in the west sector of North Qilian region are enriched in tungsten. We propose the strata were remelted to be tungsten‐granitoid during subduction. The polymetallic tungsten was gradually accumulated into the roof pendants of the granite intrusion by fractional crystallization and then was deposited by hydrothermal fluids during metasomatism and infilling along fractures. On the other hand, the granite intrusion also acted as “heating machine” to make hydrothermal fluids leach out the metals from Precambrian strata and these metals joined the ore‐forming hydrothermal system.  相似文献   

GMS卫星遥感中国地区气溶胶光学厚度   总被引：20，自引：2，他引：20       下载免费PDF全文

张军华  斯召俊  毛节泰  王美华 《大气科学》2003,27(1):23-35

讨论了利用GMS卫星遥感湖面上空气溶胶光学厚度的方法,根据在5个湖面附近与多波段光度计遥感结果的比较,对卫星遥感的方法和结果进行了检验,然后利用该方法遥感了中国大陆25个湖面上空气溶胶光学厚度.结果显示,利用卫星反演湖面光学厚度可以提供大陆上空气溶胶的信息,是研究大陆上空气溶胶光学厚度一个可行的方法.  相似文献   

应用区域地基全球定位系统观测分析北京地区大气总水汽量   总被引：30，自引：2，他引：30       下载免费PDF全文

梁丰  李成才  王迎春  毛节泰  方宗义 《大气科学》2003,27(2):236-244

利用2000年6月1日～8月11日北京地区地基全球定位系统(Globe Positioning System)网遥感大气总水汽量试验的观测资料,分析了北京地区夏季大气总水汽量的时空变化,研究了大气总水汽量与日平均温度、地面水汽压和降水的关系.研究结果表明:大气总水汽量存在明显的时空变化,对于地理位置基本相近的台站,海拔高度的影响比较明显,一般情况下高山站的水汽总量低于平原站;在晴天,地面水汽压与大气总水汽量有较好的相关性,而在云雨日,由于高低层大气湿度的变化常常不同步,用地面水汽压估算的大气总水汽量具有较大的偏差;大气总水汽量短时间内的快速增加往往对应有降水过程出现,但总水汽量的大小与降水量之间并没有明显的相关,在降水预报中应综合考虑总水汽量的前期平均水平、短时的增幅和峰值大小等条件的影响.  相似文献   

数值预报产品在2002年汛期暴雨预报中的应用   总被引：1，自引：3，他引：1  

周雨华  毛亮  何正阳  姚蓉  居晶琳 《气象》2003,29(11):41-44

为了解数值预报产品在暴雨预报中的作用，总结了欧洲中心、华盛顿、日本及中央气象台天气在线网站德国数值预报模式的高空、地面形势预报产品和降水预报产品在湖南省2002年几次典型暴雨预报中的应用情况。结果表明：数值预报产品在2002年湖南省中短期暴雨预报中发挥了重要作用。  相似文献   

用MODIS遥感资料分析四川盆地气溶胶光学厚度时空分布特征   总被引：25，自引：1，他引：25       下载免费PDF全文

李成才  刘启汉等 《应用气象学报》2003,14(1):1-7

利用MODIS卫星遥感光学厚度产品，分析了四川盆地光学厚度分布和季节变化特征。由于受沙尘天气的影响，春季四川盆地具有最大的平均光学厚度。盆地内几个大值区中，西部成都一带的中心常年维持，季节变化小；南部中心位于宜宾到重庆沿长江流域一带；东部南充到重庆间的大值中心，季节变化大，在夏季消失。光学厚度分布和季节变化的数据结果为研究区域气候变化提供了依据。  相似文献