A GIS-based method of risk assessment on no. 11 coal-floor water inrush from Ordovician limestone in Hancheng mining area,China

The no. 11 coal seam in the deep area of Hancheng mining area is mining in recent years, which is threatened by the water inrush from the Ordovician limestone aquifer. Coal-floor water inrush is governed by the water abundance of coal-floor aquifer, the water-resisting performance of coal-floor aquitard, and the pathway connecting the water source and the working face. To make an accuracy risk assessment of water inrush from the no. 11 coal seam floor, a GIS-based vulnerability index method (VIM) is adopted for its superior comprehensive consideration of more controlling factors, powerful spatial analysis, and intuitively display functions. This study firstly established an index system including the water pressure of the coal-floor aquifer, the unit water inflow, the thickness, the core recovery percentage, the thickness ratio of brittle rocks to ductile rocks, the thickness of effective aquitard, and the accumulated length of faults and folds, of which the former six indexes governed the water abundance of the coal-floor aquifer which was combined with the last two factors to determine the risk of coal-floor water inrush. Secondly, the thematic map of each controlling factor is established by GIS using the geological prospecting data, and the weight of each factor is determined by the analytic hierarchy process (AHP) after consulting the expert review panel. At last, a vulnerability index is obtained and used to assess the risk of coal-floor water inrush of the no. 11 coal seam. The risk of water inrush of the no. 11 coal seam of the study area was ranked to three zones: the southeastern shallow area in red color is the dangerous zone, the wide northwestern area in green color is the safe zone, and the transition area in yellow color is the moderate-risk zone. Compared with the actual water-inrush incidents, the risk assessment result was verified to achieve an accuracy of 82.35%, which is proved to be a dependable reference for the prevention and controlling of coal-floor water inrush of the no. 11 coal seam in Hancheng mining area.     

皖南东至兆吉口铅锌矿床成矿时代的厘定及其找矿指示意义

皖南东至兆吉口铅锌矿床是近年来在江南过渡带西段新发现的一个规模达中型的中-低温热液型矿床。目前揭露的铅锌矿体均赋存于东至断裂带及其西侧次级张(扭)性断裂及裂隙中。文章选取了该矿床主要矿石矿物闪锌矿以及与主成矿阶段金属硫化物紧密共生的石英,分别采用流体包裹体Rb-Sr法和40Ar-39Ar法进行同位素地质年龄测定。4件闪锌矿样品获得流体包裹体Rb-Sr等时线年龄为(128±1)Ma;2件石英样品获得流体包裹体40Ar-39Ar坪年龄分别为(128.74±3.02)Ma和(128.19±1.98)Ma,等时线年龄分别为(128.81±5.25)Ma和(128.30±3.47)Ma,反等时线年龄分别为(128.82±5.24)Ma和(128.31±3.47)Ma。同位素地质年龄测试结果基本一致,表明兆吉口铅锌矿床形成于128 Ma左右,成矿时代为早白垩世。该成矿年龄与赋矿闪长玢岩的形成时间((129.0±2.3)Ma~(128.4±2.7)Ma)一致,也与东至断裂燕山晚期的活动年龄((126.3±2.2)Ma)相近,表明该矿床成矿与燕山晚期的构造-岩浆活动密切相关,此时区域构造背景为强烈挤压后的伸展环境。这一矿化事件在成矿时代上明显晚于长江中下游成矿带中的断隆区(如铜陵、安庆-贵池等矿集区)的铜金多金属矿床和皖南成矿带中的钨钼多金属矿床(136 Ma),而与长江中下游成矿带断坳区的玢岩铁矿床的成矿时间(135~127 Ma)相近,指示长江中下游成矿带与皖南成矿带之间的江南过渡带中发育有燕山晚期较晚阶段(128 Ma左右)的铅锌矿化事件,为今后在该区开展铅锌多金属矿床找矿勘探提供了重要依据。     

福贡地区石炭系地层可能属于拉萨地块:来自碎屑锆石年龄谱的指示

欧亚与印度大陆的碰撞使得印度大陆的北东角强烈挤入欧亚大陆内部,形成东构造结,其引发的强烈变形将南羌塘地块、北羌塘地块、拉萨地块、保山地块、兰坪-思茅地块以及地块之间的缝合带挤压于很窄的范围内,造成青藏高原腹地与其东南缘之间构造单元划分、对比困难。滇西福贡地区位于青藏高原东南缘,东构造结影响范围内,是三江造山带及青藏高原相关地块的汇聚处。福贡地区石炭系岩石组合表明其形成于较为稳定的浅海相沉积环境中,具有被动大陆边缘沉积特征。三件石炭系二云母石英片岩碎屑锆石表面年龄数据(194个有效分析点)形成五个主要年龄区间:2550~2400Ma、1800~1550Ma、1200~1080Ma、1000~850Ma和600~480Ma,峰值分别为~2502Ma、~1724Ma、~1120Ma、~886Ma和~512Ma。对比其他地块同时代地层的碎屑锆石年龄谱表明,福贡地区石炭系可能是拉萨地块的一部分,与腾冲地块一样,属于其南延部分。结合中新生代岩浆岩带的构造连续性,我们认为,印度板块东北角向北、北东方向的强烈挤压导致拉萨地块及冈底斯岩浆岩带弯曲、缩颈、并发生分离与旋转。     

基于Hyperion高光谱数据和随机森林方法的岩性分类与分析

探索利用高光谱数据的岩性填图新方法是遥感地质应用领域的重要需求之一。本文运用随机森林方法和EO-1Hyperion高光谱数据,对新疆塔里木西北部柯坪地区的局部区域进行岩性分类,并对相关问题进行分析。分别利用光谱特征以及加入光谱一阶导数特征进行岩性分类,并对不同特征对岩性分类的重要性进行分析,同时与现有的基于光谱角制图方法(SAM)进行比较。结果表明,与SAM方法相比,随机森林方法得到了更高精度的岩性分类结果,是一种有效可行的岩性分类方法。根据特征重要性的排序,蓝绿光波段、短波红外波段以及相应的一阶导数特征对研究区Hyperion数据的沉积岩岩性分类贡献更大。     

A new evil waveforms evaluating method for new BDS navigation signals

With the advent of new global navigation satellite systems (GNSSs) and new signals, GNSS users will rely more on them to obtain higher-accuracy positioning. Evil waveform monitoring and assessment are of great importance for GNSS to achieve its positioning, velocity, and timing service with high accuracy. However, the advent of new navigation signals introduces the necessity to extend the traditional analyzing techniques already accepted for binary phase-shift keying modulation to new techniques. First, the well-known second-order step thread model adopted by the International Civil Aviation Organization is introduced. Then the extended new general thread models are developed for the new binary offset carrier modulated signals. However, no research has been done on navigation signal waveform symmetry yet. Simulation results showed that, waveform asymmetry may also cause tracking errors, range biases, and position errors in GNSS receivers. It is thus imperative that the asymmetry be quantified to enable the design of appropriate error budgets and mitigation strategies for various application fields. A novel evil waveform analysis method, called waveform rising and falling edge symmetry (WRaFES) method, is proposed. Based on this WRaFES method, the correlation metrics are provided to detect asymmetric correlation peaks distorted by received signal asymmetry. Then the statistical properties of the proposed methods are analyzed, and a proper deformation detection threshold is calculated. Finally, both simulation results and experimentally measured results of Beidou navigation satellite system (BDS) M1-S B1Cd signal are given, which show the effectiveness and robustness of the proposed thread models.     

冻土机械切削破碎机理的研究进展

冻土开挖困难、破碎效率低是高寒地区工程建设、地基施工等面临的技术难题。冻土机械切削破碎是冻土开挖的主要方法,其机理研究是提高冻土破碎效率的前提和基础。首先总结了温度、含水率、围压等对冻土复杂力学特性的影响,进而调研分析了冻土机械切削破碎的典型切削力学模型,发现冻土切削机械破碎模式不仅与冻土力学特性密切相关,也与切削参数和刀具结构直接相关,冻土切削过程中存在着最优的切削前角（30°~60°）,且深切削和浅切削时冻土内部受力方式存在差异也会导致破坏形式的不同;温度、含水率、围压所造成的冻土力学性能变化会直接导致冻土破坏过程和切削破碎机理的改变,冻土强度随着温度降低表现出先升高然后保持稳定的特性,随着含水率升高呈现出先升高后降低的趋势,冻土破碎存在脆性、塑脆过渡及塑性等不同破坏形式。通过系统总结冻土切削破碎机理研究进展,进一步明确了冻土力学性质主要影响因素、变化特点及其切削破坏损伤特征,为冻土机械切削破碎的切削参数和切削具结构优化提供了设计依据。     

长江中游沿岸地下水中有机质分子组成特征及其对碘富集的指示

长期摄入高碘地下水（碘浓度＞100 μg/L）会造成人体甲状腺机能损伤.天然有机质被认为是影响高碘地下水形成的关键组分,为研究地下水中溶解性有机质（DOM）分子组成对碘富集的影响,选取长江中游沿岸浅层地下水作为研究对象,运用傅立叶变换离子回旋共振质谱仪（FT-ICR-MS）表征不同碘浓度地下水中DOM分子组成差异.研究发现碘易富集在还原环境的浅层地下水中,地下水中碘的浓度与溶解性有机碳（DOC）浓度无显著关系,DOM分子总数越多碘浓度越高;高碘地下水较低碘水DOM分子均一性、多样性更强,氧化程度和不饱和程度更高,含更多芳香性结构.长江中游沿岸高碘地下水的形成受DOM分子组成控制,主要与不饱和程度高尤其是含芳香性结构的大分子DOM有关,含芳香性结构的DOM分子与碘络合在高碘地下水的形成过程中起重要作用.      

Comparative Study of Acid and Alkaline Stimulants with Granite in an Enhanced Geothermal System

The Enhanced Geothermal System (EGS) is an artificial geothermal system that aims to economically extract heat from hot dry rock (HDR) through the creation of an artificial geothermal reservoir. Chemical stimulation is thought to be an effective method to create fracture networks and open existing fractures in hot dry rocks by injecting chemical agents into the reservoir to dissolve the minerals. Granite is a common type of hot dry rock. In this paper, a series of chemical stimulation experiments were implemented using acid and alkaline agents under high temperature and pressure conditions that mimic the environment of formation. Granite rock samples used in the experiments are collected from the potential EGS reservoir in the Matouying area, Hebei, China. Laboratory experimental results show that the corrosion ratio per unit area of rock is 3.2% in static acid chemical experiments and 0.51% in static alkaline chemical experiments. The permeability of the core is increased by 1.62 times in dynamic acid chemical experiments and 2.45 times in dynamic alkaline chemical experiments. A scanning electron microscope analysis of the core illustrates that secondary minerals, such as chlorite, spherical silica, and montmorillonite, were formed, due to acid-rock interaction with plagioclase being precipitated by alkaline-rock interactions. Masking agents in alkaline chemical agents can slightly reduce the degree of plagioclase formation. A chemical simulation model was built using TOUGHREACT, the mineral dissolution and associated ion concentration variation being reproduced by this reactive transport model.     

中国晚泥盆世至早三叠世楔叶类植物多样性研究*

化石类群的分类单元多样性和形态多样性变化是生物宏演化的2个基本方面,而以往的研究对于后者的关注较少。晚古生代的楔叶类植物易于识别,化石记录丰富,但针对这一类群多样性演化的研究还较为缺乏。基于华北板块、华南板块晚泥盆世至早三叠世楔叶类植物属、种以及叶片形态编码数据库,对楔叶类植物宏演化历程进行详细研究。中国(华北板块和华南板块)楔叶类植物的属、种丰富度在晚古生代呈现出不稳定的持续增长,表现为晚泥盆世的初始兴盛、早石炭世杜内期至早二叠世萨克马尔期的缓慢上升、早二叠世萨克马尔期至晚二叠世吴家坪期的快速上升;晚二叠世长兴期,总体的属种多样性骤减;每百万年属种多样性在二叠纪—三叠纪之交亦有明显降低。华南板块楔叶类植物的属种多样性总体上小于华北板块,达到峰值的时间为卡匹敦期—吴家坪期,而华北楔叶类植物的属级多样性在空谷期—沃德期达到峰值。中国楔叶类植物叶片的形态多样性的剧烈变化与属种丰富度并不同步,表现为法门期至韦宪期较小,在宾夕法尼亚亚纪达到峰值,随后稍微下降并在二叠纪的大部分时段保持平稳。在晚古生代的叶片形态演化过程中,楔叶类植物的叶面积由小变大、叶片由深裂至不裂、叶尖形状由分裂变为圆形或钝圆、叶轮中的叶从大小相等到大小不等并出现叶镶嵌,这可能与当时植物群落中林下层光照强度的变化有关。     

无人机遥感技术在甘肃北山地区地质填图中的应用

甘肃北山地区岩浆岩及变质岩出露广泛,植被稀少,地势平缓,是无人机遥感开展地质填图试验的理想目标区。为解决传统地质填图方法受地形、环境限制和投入高及工作周期长等问题,选取北山长流水地区20 km²化探重点工作区为目标区,利用大疆精灵4专业版无人机采集图像,并采用Photoscan软件合成高分辨率正射影像以及三维模型,建立解译标志,对目标区域进行地质解译,获得比前人1：1万地质图更加精细的地质图。该方法较传统填图方法能够解译出地质体形态、岩脉产状、微小断裂等更详细的地质内容,并能提供划分岩脉期次的证据。