回归—马尔可夫链联合预测地震     

张启明 《地震研究》1991,(3)

本文将回归预测和马尔可夫链预测有机地结合起来,解决了单独使用回归预测时,理论值和实际值偏差较大的问题,提高了地震时间预测的精度。  相似文献   

豫西蛇尾秦岭群P-T轨迹定量计算及其地质意义   总被引：2，自引：0，他引：2  

陈能松 《地球科学》1990,15(2):145-155

河南省西峡县北部蛇尾地区秦岭群变质泥质岩系的黑云二长榴线岩中的石榴石成分环带是连续变质反应的结果。本文根据该岩石的石榴石环带成分定量计算了变质作用P-T轨迹。P-T轨迹样式表明,本区秦岭群的变质作用可以分为两大期:第一期发生在大陆碰撞带环境中,变质的温度压力演化受均匀地壳增厚及隆起侵蚀过程控制;第二期发生在岛弧环境或活动大陆边缘环境,变质温压条件早阶段与深部上升的热流有关,中阶段受侵位的炽热花岗岩体控制,晚阶段受地体背冲推覆的构造过程制约。  相似文献   

山东招掖金矿带焦家式金矿的矿床分带   总被引：2，自引：0，他引：2  

王燕  卢作祥 《地球科学》1988,(2)

本文从矿化、蚀变、构造岩、矿物组合、元素组合、矿床类型等方面,论述了招掖地区焦家式金矿矿床分带规律问题。认为该区焦家式金矿矿床分带以脉动、逆向、不对称为特征。可分出叠加式和更替式两类分带,分别与控矿断裂断面的递进式迁移和跳跃式迁移相联系,反映了构造活动中心的间歇性迁移。论文最后提出了最佳分带组合,有重要的理论和实际意义。  相似文献   

湖南东坡野鸡尾蚀变岩枝型锡多金属矿床地质特征及成因     

李忠文  崔彬  匡耀求 《地球科学》1988,(2)

野鸡尾矿床为一新型锡多金属矿床。本文研究了蚀变岩枝的特征,并论证其为千里山复式岩体第二期侵入体(γ_5~(2-2))的一个高侵位岩枝。认为矿液是沿接触带上升的。文章还研究了成矿物质的来源及成矿的物理化学条件。  相似文献   

Seismic hazard analysis for the Philippines     

S. S. Su 《Natural Hazards》1988,1(1):27-44

Two sample probabilistic hazard maps for the Philippine Region are compiled. In these are shown various levels of expected horizontal ground acceleration for some given annual probability of exceedence, namely, for 0.1% a.p.e. and for 0.01% a.p.e. Such hazard maps are needed by structural engineers for compiling seismic zoning maps. The hazard maps are derived from source-zone or seismogenic maps, which, in turn, are compiled from seismographic, geologic, and geotectonic data. Much weight is put on geotectonic data rather than on seismographic data. The former lends support to extrapolating to much longer periods of exposure time or longer periods of recurrence.  相似文献   

Application of extension theory in risk zoning of debris flow in Beijing   总被引：1，自引：0，他引：1  

BAI Liping  WANG Yeyao  SUN Jiali  GONG Bin 《世界地质(英文版)》2009,12(1):40-45

The occurrence of debris flow is affected by many factors. Risk zoning of debris flow plays a vital role in the early-warning and prediction of abrupt geological hazards, and exploration of new method is needed in the early-warning and prediction of geological hazards. The extension theory is a new method to solve contradiction matters. Based on extension theory, AHP and GIS, the risk zoning model of debris flow was established in this paper. The result of this research provides a new way in the risk zoning, early-warning and prediction of debris flow  相似文献   

耦合SOFM与SVM的生态功能分区方法——以鄂尔多斯市为例   总被引：6，自引：1，他引：6  

毛祺  彭建  刘焱序  武文欢  赵明月  王仰麟 《地理学报》2019,74(3):460-474

辨析区域主要生态环境问题及其空间异质性,划定生态功能区,对保障区域生态安全和国土开发优化具有重要指导意义。以往自下而上的分区研究多基于行政区或流域开展,难以体现行政区或流域内部的生态功能分异。以鄂尔多斯市为例,基于生态系统服务与生态敏感性构建区域生态功能分区指标体系,耦合自组织特征映射（SOFM）网络与支持向量机（SVM）划定鄂尔多斯市生态功能分区。结果表明,区域内各生态功能分区指标呈现明显的空间分异特征,通过SOFM网络基于栅格进行指标聚类,构建分类效果指数筛选最佳聚类方案,将区域分为7种不同的生态功能类型。最终,利用SVM识别最优分区界线,将鄂尔多斯市分为11个生态功能区。本文构建分类效果指数实现多分类方案优选,使用机器学习算法解决自下而上的自然分区容易弱化要素空间位置属性的问题,完成了从分类到分区的定量转换,有助于提升分区的空间精度与客观性,为生态功能分区与分区边界划定提供了新的方法途径。  相似文献   

Transformation of Fe–Ti gabbro to coronite, eclogite and amphibolite in the Baie du Nord segment, Manicouagan Imbricate Zone, eastern Grenville Province     

Cox  & Indares 《Journal of Metamorphic Geology》1999,17(5):537-555

Fe–Ti gabbros from the Baie du Nord Segment of the Manicouagan Imbricate Zone, metamorphosed under high P–T conditions during the Grenvillian orogeny, have been the focus of a detailed micropetrological study. Textures and mineral chemistry suggest that the mineral assemblages represent progressive stages of metamorphic transformation resulting in the formation of coronas, pseudomorphs after igneous phases (transitional) and true, granoblastic eclogites. The transitional and eclogitic samples also have coronas which are developed locally around igneous xenocrysts of plagioclase and olivine. The deformed margins of coronitic Fe–Ti gabbros are transformed to amphibolite and contain clinopyroxene-bearing leucosomes with garnet poikiloblasts that are indicative of high-P–T dehydration melting. Interpretation of garnet zoning and thermobarometry suggest that the highest P–T conditions are recorded by coronas around xenocrysts (c. 720–800 °C at 14–17 kbar) and garnet–clinopyroxene cores in granoblastic assemblages (c. 740–820 °C at 13–17 kbar) in the eclogitic samples. Re-equilibration during the early stages of exhumation at high-T conditions (>700 °C) affected all samples, and is evidenced by the widespread development of pargasite-bearing plagioclase collars in the coronitic and transitional metagabbros and by widespread re-equilibration of the eclogites giving lower P–T estimates at grain boundaries. However, the difference in calculated pressure conditions between coronite and eclogite samples is consistent with increasing pressure (depth) from the coronites (11–13 kbar) to the eclogites (13–17 kbar). The P–T conditions recorded by these rocks define a metamorphic field gradient which suggests high heat flow through the lower crust during the Grenvillian orogeny.  相似文献   

胶州湾海底隧道二次衬砌混凝土的耐久性设计     

刘伟  王命平  赵铁军  张曙光 《海岸工程》2008,27(2):9-16

通过对胶州湾海底隧道工程所在地的环境作用进行分析，以基于钢筋混凝土劣化模型的设计方法，对海底隧道衬砌混凝土的耐久性进行研究。结果表明，海底隧道要达到100a使用年限，其海域段行车侧混凝土保护层厚度建议为60mm加上适当施工偏差，其强度等级应取C50，氯离子扩散系数应取4×10^-12m^2／s。  相似文献   

北祁连天鹿铜矿床砂岩型铜矿石特征     

李金春 《矿床地质》2009,28(4):473-480

天鹿铜矿床是古生代海相砂页岩型铜矿.其铜矿石主要为粉砂岩型,包括斑铜矿矿石、辉铜矿矿石、辉铜矿斑铜矿矿石、黄铜矿斑铜矿矿石、黄铜矿矿石、黄铁矿黄铜矿矿石等6种自然类型.矿石结构主要为结晶结构和交代结构,矿石构造以浸染状为主.主矿层中的矿化沿岩层垂向具有明显的分带性,从底部到顶板为:斑铜矿→辉铜矿→黄铜矿→黄铁矿,具有典型的化学沉积成因铜的硫化物排列组合特征.这些特点与中国及国外海相砂页岩型铜矿相一致.  相似文献