Analysis of the Tectonic Stress Field of SE Sichuan and its Impact on the Preservation of Shale Gas in Lower Silurian Longmaxi Formation of the Dingshan Region,China

Tectonic stress is one of the most active deformation factors in the Earth’s crust. Therefore, determinations of its mode of action and form of conversion are critical for guiding research that evaluates preservation conditions in shale gas. Through a survey that targeted many structural features, such as vertical folds and conjugated joints, we investigated the revolution characteristics of the tectonic stress field, the mode of action and the sequence of tectonic stress in the Dingshan region of SE Sichuan by structural analysis methods. Meanwhile, based on a geologic analysis of tectonic stress mechanisms, the structural stress in the region using finite element numerical simulations is quantitatively analyzed. The results show that the region has experienced tectonic stress fields over four different periods and in four different orientations: NW–SE, nearly N–S, nearly E–W and NE-SW. The NW-SE force occurred earlier than that of the nearly N–S force, followed by nearly E–W compression, and finally N–E force. It is concluded that the structural framework of the study area was formed by the effects of the NE-SW compressional stress, which is still active today. The simulation demonstrated that overlapping parts of the intensive strain zone had a higher maximum principal stress, particularly in areas of energy concentration. As for mud and shale, which show excellent sealing capacity, the key to preserving shale gas is the accumulation of energy and a low degree of breakage. Considering the nip-out line of the Longmaxi Formation in the Dingshan region, the buried depth limit of shale-gas production (4500 m), and fault length, the preservation conditions of shale gas and identified favorable targets within the Longmaxi Formation is evaluated.     

吉林福安堡钨钼矿床的发现及意义

在吉林省的吉林地区中部和北部大面积森林覆盖区,分布着大面积华力西期、印支期花岗岩类,受传统成矿理论的束缚,这一地区成为有色金属矿产勘查的"处女地"。新一轮1∶20万化探扫面之后,相继开展了不同方法的地球化学异常查证工作,从中发现了很有前景的福安堡钨钼矿床。实践证明,在东北森林覆盖区化探找矿方法十分有效,而且可以尽可能减少地质勘查过程中对植被的破坏,对保护生态环境起到积极的作用。     

新疆阿尔泰蒙库铁矿床的辉钼矿Re-Os年龄及意义

蒙库大型铁矿位于阿尔泰南缘麦兹盆地,赋存于晚志留世-早泥盆世变质火山-沉积岩系中,容矿岩石为石榴石矽卡岩、变粒岩、浅粒岩和大理岩.矿体总体顺层分布,空间上与矽卡岩密切相关.对1号矿体含黄铁矿辉钼矿石英大脉中辉钼矿Re-Os同位素年代学进行了研究,7件样品的Re-Os同位素模式年龄为(261.6±3.7)～(264.0±...     

开封城市生态系统健康动态变化研究

从城市生态系统健康内涵出发,结合开封市实际情况,建立了开封城市生态系统健康评价指标体系.采用基于熵值的赋权法来确定指标权重,通过建立城市生态系统综合评价模型,对开封城市生态系统健康状况进行评价.结果显示:2002-2010年开封城市生态系统健康指数呈总体上升趋势,表明开封城市生态系统健康状况逐年好转;但从健康等级来看,健康水平一直处于不健康和亚健康级别,总体健康状况不容乐观;从3个子系统来看,城市生态系统健康水平的提高更多地得益于社会子系统与经济子系统的优化和完善,而自然子系统没有发生明显改观,对城市生态系统健康水平的提高并未起到积极作用.     

Variability of modeled runoff over China and its links to climate change

Runoff is a key component of the water cycle over land, with direct impact on regional ecosystems and water resources. This study investigates historical runoff variability and change over China in 1951–2008 using the Community Land Model and in situ observations of atmospheric forcing fields. Model simulations are first evaluated against in situ observations of streamflow for four major rivers, as well as soil moisture and water table depths, before further analysis is conducted. Then, quantile regression is used to analyze runoff variability and its relation to precipitation and temperature. The spatial pattern of monthly climatological runoff over China is characterized by maxima in the humid south and a gradual decrease toward the arid northwest. Runoff increases in the humid south, slightly decreases in the transition zone, and shows nonsignificant trends in the arid northwest. The footprint of decadal variability can be seen from 1951 to 2008. The annual precipitation advances the spatiotemporal variability of runoff despite locally distinct runoff–precipitation responses. The runoff-temperature relationship shows complex spatiotemporal characteristics that depend on the feedback from precipitation.     

渤海海域软土层土对地震动参数的影响研究

渤海海域软土层土对场地设计地震动参数取值具有显著影响.选取渤海中部钻孔剖面作为计算场地模型基础,分别构建软土和硬土场地模型,并通过改变软土层厚度,构造新的场地模型.采用等效线性化方法(EL法)和非线性计算方法(NL法)分别对场地模型进行地震反应分析,分析了海底软土层土对地震动参数的影响.研究结果表明:海底软土层土对地震...     

新疆乌恰2次5.1级地震加速度记录特征对比分析

分析新疆乌恰两次5.1级地震4个强震台的强震动记录,第1次地震4个台记录卓越频率在4.25 Hz-13.59 Hz;第2次地震4个台记录卓越频率为2.45 Hz-3.61 Hz.从谱比曲线可以看出,2次地震在同一观测场地的场地效应基本相似,基岩台场地效应在高频部分有明显放大作用,土层场地在高频部分有明显的减小作用.     

基于分子标记的藻类鉴定研究进展

藻类鉴定被广泛应用于藻类遗传学、生理学、生态学和应用藻类学,尤其是藻类调查和评估.然而,基于形态学的鉴定往往因为分类特征未出现或不典型、设备限制和人员经验欠缺等原因带来较大误差.随着测序技术的不断发展,分子标记已成为藻类鉴定的一个通用工具.由于藻类类群众多且差异很大,分子标记的选择成为藻类鉴定的关键.本文综述了蓝藻、硅藻、绿藻、甲藻、裸藻、隐藻、金藻、黄藻、红藻和褐藻等主要门类分子标记的选择及应用进展,包括分子标记选择原则、常用标记和相应序列数据库,以及各个分子标记在不同类群应用中的优缺点等.藻类分子鉴定源于编码核糖体RNA的基因（rDNA）,发展于细胞核、线粒体、叶绿体DNA等.然而,当前藻类分子鉴定逐渐细化和完善,单一的核糖体DNA、内转录间隔区（ITS）和保守蛋白编码基因等短序列分子标记已经很难满足藻类鉴定的需求,多标记组合成为一种必然选择.同时,线粒体基因组、叶绿体基因组、核基因组、转录组和宏基因组等提供了更多遗传进化信息,弥补了短序列分子标记在系统分类应用中的不足.对于藻类鉴定,单纯依赖分子标记或形态学都不足以保证鉴定的准确性,采用将分子生物学、形态学、生理生化学等结合的多相学方法,才能准确地完成鉴定工作.此外,藻类分子数据库的建立和完善是未来分子鉴定的重要工作,快速鉴定方法也必将在未来获得广泛的应用和发展.     

洱海北部湖区轮虫群落季节演替特征

洱海是位于我国西南亚热带高原地区的重要淡水生态系统,在高强度的人类活动与气候变化的影响下出现了较为严重的水质退化与富营养化现象,其中北部湖区的问题最为突出。本文以北部湖区为对象,设置了喜洲等5个样点,于2020年3、6、9和12月对该湖北部的轮虫群落及环境因子进行了季节性调查,分析了轮虫群落的季节演替特征及主要影响因子。本次调查共检出26属48种轮虫,多数种类为广布种或暖水种,其中无柄轮属、晶囊轮属、胶鞘轮属、须足轮属、龟甲轮属、多肢轮属在4个季节均出现。异尾轮属的种类数最多,共计9种。螺形龟甲轮虫、长肢多肢轮虫和前节晶囊轮虫是主要的优势种类。其中,螺形龟甲轮虫在4个季节均为丰度优势种,而前节晶囊轮虫在4个季节均为生物量优势种。非度量多维尺度分析表明,洱海北部湖区轮虫群落结构存在显著的季节差异。这种季节差异主要反映了水温的直接与间接影响,后者主要表现为鱼类捕食压力与食物资源的季节性。冗余分析表明,透明度、温度和浮游植物丰度为解释轮虫群落结构变化的重要变量。群落的物种组成与季节变化反映了主要轮虫优势种类对水温和水质变化的敏感性。     

九江-瑞昌5.7级地震余震的S波分裂研究

Shear wave splitting is studied based on the digital waveforms of three seismic stations DJS, SZD and WUJ, which were set up after the Jiujiang-Ruichang MS5.7 earthquake of November 26, 2005 around the epicenter area. The result shows that the time delays of slow shear waves of the DJS station, which is not far from the epicenter and where the distribution of faults is complex near the station, are relatively larger and the polarization directions of fast shear waves are not concentrated; the predominant polarization direction of fast shear waves of WUJ station, with single fault distributed nearby, has a difference of 35° to the strike of the fault and is inconsistent with the direction of regional principal compressive stress. The predominant polarization direction of fast shear waves of SZD station with no faults nearby is in accordance with regional principal compressive stress. There is no obvious regular relationshipship between the delay time and the focal depth.