利用RS和GIS进行成都市扩张及驱动力分析

本文利用多时相TM影像,基于GIS空间分析技术,运用缓冲区分析方法和因子分析方法,对成都市城市扩张及其驱动力进行了定量分析.结果表明:城市扩张在各缓冲带空间分异显著,城市扩张呈明显的“圈层式”扩展模式,总体上紧邻城市中心区域,具有较强的空间集中性,随城市中心到周边区域,空间集聚性减弱.城市扩张呈现不同的空间分异性;区域...     

应用新型散度方程诊断暴雨的触发和增幅机理

分析散度及其变化是进行暴雨研究的途径之,而传统的散度方程不能显示包含热力场分布影响散度演变的问题。因此,利用陈忠明等导出的新型散度方程和NCEP/NCAR(1°×1°经纬度)再分析资料,针对贵州省2007年7月25—26日持续性大暴雨天气过程,通过计算新型散度方程中的各项,定量诊断分析大气运动的正压非平衡强迫、湿斜压非地转与风垂直切变耦合强迫在暴雨发生发展过程中的作用,并与地面1、6h降水观测资料和卫星云图资料进行对比分析。探讨正压非平衡强迫、湿Q矢量与垂直风切变的湿斜压热动力耦合强迫导致辐合增加与暴雨发生、发展的动力机制。结果表明:强降水主要发生在近中性或弱不稳定层结条件下。大气运动的正压非平衡强迫导致辐合增加是强降水过程的触发机制;在暴雨维持和增幅过程中,湿斜压热动力耦合强迫在强降水的维持方面扮演了重要角色。当强降水过程发生后,才存在湿斜压热动力耦合强迫作用,湿斜压热动力耦合强迫作用是暴雨增幅的动力机制。未来6小时强降水发生的区域、降水强度、中心位置与散度演变的强负值区变化一致。新型散度方程对强降水预报有指导意义,可以作为诊断散度场演变的一种有效的数学工具。     

局部相关加权中值滤波技术及其在叠后随机噪声衰减中的应用

随机噪声的衰减和同相轴连续性的提高可以极大地改善地震资料解释的精度.本文提出一种新的滤波技术,既能够有效地衰减随机噪声又可以很好地保护地震资料中的断层等信息不被破坏,增强地震剖面中弯曲、倾斜同相轴的连续性.该方法结合新的加权中值滤波技术和两种构造信息保护滤波策略,实现基于预测数据体和基于倾角走向的加权中值滤波.通过设计...     

Structural features and metallogenesis of the Carlin-type Jinfeng (Lannigou) gold deposit, Guizhou Province, China

Jinfeng, previously known as Lannigou, is the largest Carlin-type gold deposit in the Yunnan–Guizhou–Guangxi region in southwestern China. Gold mineralization in the Jinfeng deposit is almost entirely fault-hosted and structurally controlled, with very little disseminated ore occurring in the adjacent host rocks. The structural elements in the Jinfeng deposit can be subdivided into 3 groups comprising NS-, NW-, and NE-striking faults and folds, with NW-striking structures controlling the overall framework of the deposit. Four tectonic stages have been recorded in the Jinfeng area, i.e., rifting, orogenic compression, lateral transpression, and lithospheric extension. A series of contemporaneous normal faults, such as the N-striking and east-dipping F1 and F7 faults developed along the edges of a carbonate platform during basin rifting (D₂–T₂). These structures provided an initial framework for subsequent basin evolution, and also represent the principal hydrothermal conduits. A gradual change of the compression direction during the orogenic stage (T₃) from E→W to NE→SW, gave rise to the NW-striking structures, including large, tight to overturned folds such as the Huangchanggou synclinorium and associated thrusts such as the F3 fault. The development of these orogenic, predominantly NE-dipping structures, as well as accompanying NE-striking dextral shear and transform faults (such as the F2 fault) along the margin of the Laizishan Dome established the structural pattern of the deposit area. The NW-striking folds were refolded by NE-striking superimposed folds during post-collisional lateral transpression (J₁) and NW–SE directed compression. Oblique stress distribution gave rise to NS-trending compression and EW-trending extension, with dilational zones developing at the intersection of the F2 and the F3 faults east of the Laizishan dome. It is these dextral- and sinistral-normal dilational zones in which gold was precipitated during the main ore-forming event at Jinfeng. Following the main ore stage lithospheric extension occurred during the Yanshan stage (J₂–K) resulting in minor reverse faults that in places cut pre-existing structures. The above four main structural deformation stages mirror the evolution of the Youjiang Basin from inception to basin inversion and post-orogenic collapse and renewed extension. Significant gold metallogenesis at Jinfeng occurred during the transition from collisional compression to extensional tectonics in the early Jurassic, and is focussed into intersections of F2 and F3 and fault splays adjacent to F3. This structurally controlled gold metallogenic model is likely to be applicable to analogous settings elsewhere in the Yunnan–Guizhou–Guangxi triangle area, and has implications for the targeting of Carlin-type gold mineralization in this region.     

断层相关褶皱的三维构造几何学分析:以川西三维地震工区为例

现有的断层相关褶皱理论均基于平衡剖面原理而建立的二维几何学模型。所谓的假三维模型则是通过一系列的二维剖面复合而成的,真正意义上的三维断层相关褶皱理论尚未确立,仍然处于探索阶段。本文采用Trishear 4.0和GoCad软件,分别构建一系列不同位移量的断层转折褶皱和三剪断层传播褶皱的二维正演剖面,将这些正演剖面按照一定的线性位移梯度平行排列,从而建立起断层转折褶皱和三剪断层传播褶皱的假三维理论模型并加以分析和讨论。进而选取川西南盆地中三维地震勘探所覆盖的邛西断层转折褶皱和盐井沟断层传播褶皱,作为真三维实际解释模型的两个实例。研究表明,邛西背斜是一个典型的剪切断层转折褶皱,盐井沟背斜是一个典型的三剪断层传播褶皱;断层相关褶皱的假三维理论模型与实际解释模型的对比分析,可以看出沿背斜走向的位移梯度是控制三维构造几何学特征的基本因素,然而自然界断层面几何学的复杂多变以及岩层力学性质的各向异性,是造成断层相关褶皱真三维理论模型难以建立的主要原因。     

江西湖口隧道工程地质条件评价

论述了江西湖口隧道场区的地层岩性条件。根据断层、层面、节理结构面的组合赤平投影图,判定了隧道西洞口与东洞口自然斜坡的稳定性,以及隧道西洞口、东洞口SW、东洞口NE路堑坡的稳定性。F2、F2′、F3断层横切洞体,断层与洞体交汇处及软岩分布区,围岩不稳定,易出现掉块及小塌方。提出了短开挖、弱爆破、强支护、先排水隧道的施工方案。     

马河崩塌堆积体结构特征与稳定性评价

马河崩塌体堆积边坡坡度陡峭,起伏变化大,钻孔勘探难以准确查明边坡松散覆盖层厚度、边坡下伏基岩起伏情况及其风化发育程度。选用地震散射剖面的物探方法探明了马河崩塌堆积体结构特征,并采用多种极限平衡法(Bishop、Janbu、Morgenstern-Price)计算和对比基覆界面的安全系数,评价马河崩塌堆积体在三种不同工况下(自然工况、地震工况、降雨工况)的稳定性。得出结论为:马河崩塌堆积体的地质结构可分为三层:靠近地表为厚度为30~40m左右的松散覆盖层,未胶结; 中间为厚度10~15m的中-强风化层,节理裂隙发育; 40~50m以下为完整性较好的基岩,波速在2500m s-1以上。对地震和降雨2种不利工况进行了稳定性评价:在地震工况下,崩塌体可沿着覆盖层底界面或者风化层底界面发生失稳破坏; 在降雨工况下,崩塌体可沿着风化层底界面发生失稳破坏。     

Impact of salt-related palaeotopography on the distribution of turbidite reservoirs: Evidence from well-seismic analyses and structural restorations in the Brazilian offshore

The dynamic of gravity-driven turbidity currents is strongly influenced by the morphology of the seafloor, formed by topographic highs and lows on the margin along the depositional profile. This paper focuses on the methodology and the main results of a study on the palaeotopographic controls in a turbidite succession, with an application in an oilfield of the Brazilian offshore Campos Basin. This basin is located in the Brazilian passive margin, on which tectonics is partly controlled by halokinesis; the selected reservoirs are confined Turonian to Campanian siliciclastic turbidite systems.Six seismic-lithologic horizons of regional extension were mapped, from the Aptian salt to the Miocene as well as related faults. Four main reservoir-scale units were identified, stratigraphically comprised between two of the regional horizons, and their related surfaces were mapped. The complete ensemble of horizons and faults was used to build a multi-2D geological model. Individual surface restorations performed in every horizon allowed the structural coherence and the unfolding-unfaulting quality to be evaluated. Multi-surface restorations were then carried out in order to determine the related horizon palaeotopography of each reference depositional time.The results of the geological modeling and of the structural restorations indicate that the halokinesis-related listric faults regulated the distribution of the basal reservoirs. Additionally, at the top of the Albian carbonates, a canyon was identified, which, in association with the tectonic structures form the palaeotopographic constraints for the upper reservoir geometry.This work sheds light on the importance of structural restoration in understanding the tectonic-sedimentation interactions and the palaeotopography to the distribution of the studied turbidite reservoirs.     

广西永福县土地利用变化驱动力分析

以永福县1996--2005年土地利用变更数据和经济统计年鉴为依据,研究其10年间土地利用类型的变化,分析土地利用动态变化和利用程度变化情况,探讨土地变化的驱动因素。认为社会发展和经济增长、人口和城镇化水平以及宏观政策是影响其土地利用变化的3个主要驱动力因素。     

汉石桥湿地南部核心区富营养化成因及防治对策

为查明汉石桥湿地南部核心区的富营养化现状和成因,于2019年3—9月对该区域水体的温度、pH值、溶解氧、透明度、光照强度、化学需氧量、高锰酸盐指数、总氮、总磷、叶绿素a等指标进行定期检测分析。采用综合营养状态指数法评价南部核心区富营养化程度,采用Pearson相关性分析叶绿素a与各项水质指标之间的关系,采用主成分分析法研究水体富营养化的驱动因子。结果表明:南部核心区处于轻度-中度富营养状态;叶绿素a与透明度、pH值、溶解氧呈显著负相关,与光照强度、水温、化学需氧量、总氮等呈显著正相关,总氮是藻类生长的限制因子;水体富营养化的主要驱动因子为光照强度、水温、叶绿素a,其次为总氮与总磷。提出再生水利用、水动力条件改善、水生生物调控等防治对策,为汉石桥湿地的水生态保护和修复工作提供科学依据。