Identifying gravity anomalies caused by granitic intrusions in Nanling mineral district,China: a multifractal perspective

Several power‐law relationships of geophysical potential fields have been discussed recently with renewed interests, including field value–distance () and power spectrum–wavenumber () models. The singularity mapping technique based on the density/concentration–area (C–A) power‐law model is applied to act as a high‐pass filter for extracting gravity and magnetic anomalies regardless of the background value and to detect the edges of gravity or magnetic sources with the advantage of scale invariance. This is demonstrated on a synthetic example and a case study from the Nanling mineral district, Southern China. Compared with the analytic signal amplitude and total horizontal gradient methods, the singularity mapping technique provides more distinct and less noisy boundaries of granites than traditional methods. Additionally, it is efficient for enhancing and outlining weak anomalies caused by concealed granitic intrusions, indicating that the singularity method based on multifractal analysis is a potential tool to process gravity and magnetic data.     

我国东部春季土壤湿度影响夏季降水

该项目受到国家自然科学基金项目和国家基础研究发展规划项目的资助.最新研究成果揭示中国东部春季土壤湿度与夏季降水有联系.春季,从长江中下游到华北的土壤偏湿,对应着中国夏季东北和长江流域降水偏多,华北和南方降水偏少.     

电离层对台风响应的全过程的特例研究

作为特例研究,本文对1988年和1990年两次强台风影响期间的电离层多普勒记录及相应的台风资料进行了细致的相关分析,目的是利用多普勒记录的连续性优点来了解电离层对登陆（或近海）强台风通过声重波响应的演化全过程.分析表明,在这两次台风影响期间,电离层形态中除有明显的波状扰动（中尺度声重波）出现外,还有一些值得注意的新现象：波动的时间演化表现出明显的幅度逐渐增加以及频率由高频向低频转变,在振幅很大的情况下日落后同时出现扩展F（Spread F）现象,显示了声重波在激发电离层不规则结构方面的种子作用.这一演化过程与电离层中TIDs的线性传播理论一致,文中开展了对这一现象的非线性数值模拟,模拟结果基本上也与上述观测现象相吻合.     

河南省区域地质概况

河南省大地构造跨华北、华南两大板块,属于华北陆块、北秦岭褶皱带、南秦岭褶皱带。地层发育,古生物化石丰富,各期岩浆活动频繁,地质构造复杂。在地壳演化历史中可分为３个阶段,即太古代—中元古代为前造山阶段,晚元古代—三叠纪为主造山阶段,侏罗—白垩纪为后造山阶段。     

水文政策法规建设回顾与展望

新中国成立以来,我国水文政策法规建设取得了显著的成效,初步建立了水文管理的政策法规体系。本文对全国水文政策法规建设情况进行了回顾,对当前水文政策法规建设的问题进行了分析,并对今后一段时期水文政策法规建设的前景进行了展望。     

义县金矿成困矿物学研究

义县金矿是我国新发现的一个金矿床,矿床规模较大,品位高,矿石成分简单,易采易选。矿床受地层、断裂、岩脉活动等因素影响,并有多源特证。     

用于人卫激光测距仪的跟踪控制和数据处理系统

介绍一种用于人卫激光测距仪的望远镜转台跟踪控制和数据处理系统。该系统具有卫星轨道计算、跟踪控制测量、数据采集和跟踪误差可实时修正以及跟踪状态在计算机屏幕实时显示等多种功能，使我国ＳＬＲ网的观测水平跃上一个新的台阶。     

Distribution of the Ordovician Fluid in the Tahe Oilfield and Dynamic Response of Cave System S48 to Exploitation

The Tahe Oilfield is a complex petroleum reservoir of Ordovician carbonate formation and made up of spatially overlapping fracture-cavity units. The oilfield is controlled by a cave system resulting from structure-karst cyclic sedimentation. Due to significant heterogeneity of the reservoir, the distribution of oil and water is complicated. Horizontally, a fresh water zone due to meteoric water can be found in the north part of the Akekule uplift. A marginal freshening zone caused by water released from mudstone compaction is found at the bottom of the southern slope. Located in a crossformational flow discharge zone caused by centripetal and the centrifugal flows, the main part of the Tahe Oilfield, featuring high salinity and concentrations of CI^- and K^＋＋Na^＋, is favorable for accumulation of hydrocarbon. Three types of formation water in the Tahe Ordovician reservoir are identified： （1） residual water at the bottom of the cave after oil and gas displacement, （2） residual water in fractures/pores around the cave after oil and gas displacement, and （3） interlayer water below reservoirs. The cave system is the main reservoir space, which consists of the main cave, branch caves and depressions between caves. Taking Cave System S48 in the Ordovician reservoir as an example, the paper analyzes the fluid distribution and exploitation performance in the cave system. Owing to evaporation of groundwater during cross-formational flow, the central part of the main cave, where oil layers are thick and there is a high degree of displacement, is characterized by high salinity and Br^- concentration. With high potential and a long stable production period, most wells in the central part of the main cave have a long water-free oil production period. Even after water breakthrough, the water content has a slow or stepwise increase and the hydrochemistral characteristics of the produced water in the central part of the main cave are uniform. From the center to the edge of the main cave, displacement and enri     

Machine Learning of Mineralization-Related Geochemical Anomalies: A Review of Potential Methods

Research on processing geochemical data and identifying geochemical anomalies has made important progress in recent decades. Fractal/multi-fractal models, compositional data analysis, and machine learning (ML) are three widely used techniques in the field of geochemical data processing. In recent years, ML has been applied to model the complex and unknown multivariate geochemical distribution and extract meaningful elemental associations related to mineralization or environmental pollution. It is expected that ML will have a more significant role in geochemical mapping with the development of big data science and artificial intelligence in the near future. In this study, state-of-the-art applications of ML in identifying geochemical anomalies were reviewed, and the advantages and disadvantages of ML for geochemical prospecting were investigated. More applications are needed to demonstrate the advantage of ML in solving complex problems in the geosciences.     

基于CryoSat-2测高数据的北极格陵兰海海冰干舷高提取研究

北极是全球气候和环境变化的驱动器之一,获取北极海冰的时空特征和变化规律对研究北极以及全球气候变化意义重大。格陵兰海是北极海冰剧烈变化的区域之一,采用CryoSat-2的雷达测高数据,获取了格陵兰海的海冰干舷高分布,并利用波弗特环流计划(BGEP)仰视声呐(ULS)数据进行了验证。研究结果表明,格陵兰海海冰干舷高和分布范围存在明显的季节性变化特征,具体体现在格陵兰海海冰从10月份进入冻结期开始,海冰分布范围不断扩张,海冰干舷高也逐渐增大,2月份平均干舷高达到最大(0.2 m),之后格陵兰海海冰开始消融,覆盖范围不断内缩,9月海冰干舷高降至最小(0.13 m)。