饱和砂土地震液化判别的可拓聚类预测方法

基于可拓学的物元模型和聚类分析原理,提出了饱和砂土地震液化判别的可拓聚类方法。选取地震烈度、震中距、砂层埋置深度、地下水位、标贯击数、平均粒径、不均匀系数和动剪应力比等8个影响因素,作为饱和砂土地震液化的评价因子,构建了经典域物元和节域物元。应用物元理论和可拓集合中的关联函数,建立预测模型,通过聚类分析得到饱和砂土地震液化的判别结果。实例研究表明,该模型能客观地反映砂土的液化规律,可拓聚类预测方法应用于饱和砂土地震液化判别是有效可行的。     

Ricker子波核支持向量回归的Mercer条件拓展问题研究

Ricker子波核支持向量回归方法是消减地震勘探记录强随机噪声的新滤波技术.用判定支持向量允许核函数的Mercer条件探讨Ricker子波核函数的有效性,经过数值计算相应的核矩阵的最小特征值,发现在一个较大范围内存在极小的负值带,数量级为10^-13~10^-16,且在正值带中亦存在10^-13~10^-15数量级的量.考虑到正负极小量值的计算误差机理相近,认为判定核函数有效性的Mercer条件在工程应用时有可能适当放宽,即核矩阵不严格半正定,接近半正定亦可.为了将Ricker子波核支持向量回归滤波方法向实际应用发展,本文对不同的理论模型的Ricker子波核滤波和小波变换滤波、自适应维纳滤波这三种技术的效果进行了比较,包括时域波形、频域振幅谱、滤波前后的信噪比以及均方误差等方面.结果表明,Ricker子波核滤波方法优于另两种方法.为实际应用Ricker子波核滤波方法奠定基础.     

渤海湾盆地构造圈闭类型与勘探方向——以济阳坳陷为例

提出了渤海湾盆地初期挤压、早期张压交替、中后期持续张裂的新的成盆模式,并在该模式指导下,以济阳坳陷为例总结了盆内深层压性、张性、张压复合作用等多种成因的构造圈闭类型及其石油地质意义,最后指出盆内勘探的有利方向.     

高黎贡山脉南部的晚新生代构造-重力垮塌及其成因

云南西部高黎贡山脉构成青藏高原东南边界的一部分,平均海拔3000m以上,山脉南部高度突然下降到海拔2000m左右,线性延伸的山体变为平缓起伏的面状高地。野外工作发现,这一地貌突变是由于伸展变形和重力垮塌造成的。晚新生代以来高黎贡山脉中段和南段东西两侧均发育伸展构造,其中分隔盆地与山脉地貌单元的主要正断层被称为高黎贡山脉东坡和西坡主边界正断层,它们控制了山脉两侧盆地沉积及腾冲地块内部的火山喷发作用,造成山脉与盆地的地势差距、山体的构造剥蚀以及水系的下切。高黎贡山脉及其西侧的腾冲地块构成青藏高原周边唯一的伸展边界。这些伸展构造是畹町、瑞丽、梁河等左行走滑断裂的尾端转换构造。畹町断裂的左行走滑运动将上部地壳物质向东、向西拉开,使得高黎贡山脉南部发生构造-重力垮塌变形,形成三角形的构造窗,暴露出由变质结晶岩系构成的保山地块基底。磷灰石裂变径迹年龄表明,大约距今14Ma开始的构造-重力垮塌去顶作用首先发生在山脉南部,并逐渐向北发展,高黎贡山脉中部在距今8~5Ma进入伸展构造的强烈活动期。     

The effect of mantle composition on density in the extending lithosphere

The density distribution of the lithosphere is non-linear and discontinuous due to complex mineralogy and, most importantly, phase transitions. We evaluate the influence of changes in mantle composition on lithospheric density and its evolution during horizontal stretching, using thermodynamic calculations of the density as a function of pressure, temperature and composition. We also develop a simple parameterization based on end-member mineral reactions and geometric relationships between the geotherm and the phase boundary for comparison. The garnet–spinel peridotite transition leads to a moderate decrease in density of the mantle part of the lithospheric column at the initial stages of stretching. When the crust is sufficiently thinned and temperature is relatively high, plagioclase peridotite becomes stable in the upper part of the mantle. The density reduction due to the plagioclase-in reaction is controlled by bulk Al₂O₃ in the mantle and by the depth of the plagioclase-in reaction, which is mainly governed by the Na₂O/Al₂O₃ ratio. Since Na₂O and Al₂O₃ increase with the fertility of the mantle the phase transition effect is most pronounced for relatively fertile mantle (and strong extension) and can lead to 2.3% density reduction. This is equivalent to heating the entire lithosphere by 700 °C if only the effect of thermal expansion on density is taken into account. The formation of plagioclase peridotite can explain syn-rift uplift in sedimentary basins that experienced large mantle stretching without invoking an unrealistically strong increase in temperature. It might also be responsible for the break-up unconformity observed at continental margins.     

Early Miocene stratigraphy of central west Anatolia,Turkey: implications for the tectonic evolution of the eastern Aegean area

Small‐mammalian faunas enable the discrimination and correlation of uppermost Lower Miocene lacustrine sedimentary units in central western Anatolia. On the basis of sequential stratigraphic relationships, early Early Miocene and latest Early Miocene relative ages are suggested for the older lacustrine mass‐flow deposits and younger paper shale units, respectively, which are devoid of age‐diagnostic fossils. In central western Anatolia, the sequential differences between the uppermost Lower Miocene successions delineate a deformation zone of NE–SW‐trending fault blocks separated by vertical faults. This deformation zone, inherited from Late Oligocene tectonics, underwent an early Early Miocene sinistral transtension leading to pull‐aparts that were emplaced by granitoids. Limited extension caused the late Early Miocene repetitive up‐ and down‐wards motions of the fault blocks, with variable magnitudes. This led to contrasting subsidence histories in the relevant basinal system. During the latest Early Miocene, fault blocks coalesced into a regional body characterized by uniform slow subsidence and non‐extensional deformation facies. The general trend of the above tectonic events can be explained by lateral slab segmentation and progressive asthenospheric wedging, in response to NE‐directed and decelerated palaeosubduction in the Aegean. Copyright © 2007 John Wiley & Sons, Ltd.     

南海北部陆缘深水-超深水盆地成因机制分析

本文以海洋地质调查和油气勘探开发中积累的地质和地球物理资料的解释和分析为基础,描述和划分了南海北部被动陆缘地壳岩石圈结构构造单元,由陆向海划分出近端带、细颈化带、远端带和洋陆转换带（OCT,含边缘高地）四个构造单元.从细颈化带到OCT基本处于现今陆架坡折带之外的深水-超深水区的范围,以强烈的地壳薄化和发育大型拆离断层控制的拆离盆地为特征.这些深水-超深水盆地的同裂陷阶段均经历了早期均一断陷、中晚期拆离式断陷的演化过程,受控于南海北部大型拆离断层作用及其所导致的岩石圈临界破裂过程.新的深水-超深水盆地形成机理的认识为南海北部陆缘岩石圈的非瞬时伸展破裂过程的分析提供了新的视角,同时,陆缘深水-超深水盆地具有独特的构造-沉积体系配置和构造-热演化过程,将为科学评价南海北部陆缘深水-超深水盆地油气勘探潜力提供新的思路.     

两个西边界流延伸体区域中尺度涡统计特征分析

黑潮和湾流是世界大洋中最典型的两支西边界流,黑潮延伸体（Kuroshio Extention,KE）和湾流延伸体（Gulf Stream Extention,GSE）区域中尺度涡活动十分活跃。本文综合利用卫星高度计资料和Argo浮标资料,对KE和GSE区域中尺度涡的表层特征及其对温盐影响进行了统计研究和对比分析。结果表明:黑潮和湾流主轴附近为涡旋频率的高值区,主轴南北两侧分别以气旋涡和反气旋涡数量占多,主轴附近的涡旋强度明显大于其他区域;两个区域的涡旋以西向移动为主,气旋涡和反气旋涡都具有向南（赤道）偏离的趋势;两个区域的涡旋数量都以夏、秋季较多,涡旋强度都在春、夏季较大,且GSE区域涡旋强度明显大于KE区域;气旋涡（反气旋涡）引起内部明显的温度负（正）异常,KE区域气旋涡（反气旋涡）内部呈"负-正"（"正-负"）上下层相反的盐度异常分布,GSE区域气旋涡（反气旋涡）在各层呈现较为一致的盐度负（正）异常;两个区域中尺度涡对温盐场的平均影响深度可达1 000×104 Pa以上。     

南沙海区万安盆地构造演化与成因机制

本文基于地震、钻井和区域地质资料,运用回剥法和平衡剖面技术定量研究了万安盆地的构造沉降和伸展程度,重建盆地的构造演化史并探讨其成因机制。模拟结果表明,万安盆地构造沉降曲线为多段式,其南北部构造沉降差异明显,且沉降中心逐渐向南发展的趋势。晚始新世-渐新世（37.8~23.03 Ma BP）盆地中、北部快速沉降,存在两个沉降中心;早中新世（23.03~16.0 Ma BP）盆地南部也发生快速沉降,整个盆地存在3个沉降中心;中中新世（约16.0~11.63 Ma BP）沉降作用减弱,盆地进入裂后热沉降期。万安盆地的伸展和形成演化呈现北早南晚的特征,与南海海底扩张密切相关,同时受控于万安断裂带交替地右旋-左旋走滑作用,是伸展和走滑双重作用的结果。盆地的构造演化过程可细分为4个阶段:初始裂谷期、主要裂谷期、走滑改造期和裂后加速沉降期。     

内蒙古图古日格金矿床二叠纪侵入岩锆石U-Pb年龄与地球化学特征

对内蒙古图日格金矿区内的侵入岩开展了地质年代学和地球化学研究.LA-ICP-MS锆石U-Pb测年结果表明,图古日格矿区内的似斑状花岗岩、花岗岩、角闪石岩和蚀变闪长岩的成岩年龄分别为264.5±1.4 Ma、278.7±1.0 Ma、280.6±1.3 Ma和288.0±2.6 Ma,均侵位于二叠纪.图古日格金矿床的成矿...