A rock fall of the north Zhongtiao Shan fault and the Yongji earthquake in 793, Shanxi Province,North China

Earthquake is the main driving factor of landslides, and a large number of empirical formulas for seismic parameters have been proposed. This article studies a rock avalanche triggered by a paleoearthquake and two trial trenches in Yongji, Shanxi Province. Six quartz samples were collected from different parts on the top of the boulder, and the youngest ¹⁰Be exposure age is 1173 ± 123 years, which is considered as the occurrence time of the rock fall. The trenches excavated near the boulder infer that there was an earthquake between 2000 ± 110 and 465 ± 45 cal a bp in the north Zhongtiao Shan (NZS) fault with a maximum vertical displacement of 1.5 m and the surface rupture length (SRL) of ~35 km corresponding to a magnitude (M _S) of 6.70 ± 0.12 based on the displacement. Taking into account the occurrence time and minimum magnitude triggering the rock fall, the latest paleoearthquake revealed by trenches may be the forcing factor. Furthermore, according to historical records of Yongji, the earthquake of magnitude 6 in ad 793 is in consistency with the occurrence time and magnitude of the earthquake triggering the landslide. Therefore, the rock fall is related to the paleoearthquake revealed by the trenches, which may be the 793 Yongji earthquake.     

Climate-change driven range shifts of anchovy biomass projected by bio-physical coupling individual based model in the marginal seas of East Asia

Recent studies in the western North Pacific reported a declining standing stock biomass of anchovy (Engraulis japonicus) in the Yellow Sea and a climate-driven southward shift of anchovy catch in Korean waters. We investigated the effects of a warming ocean on the latitudinal shift of anchovy catch by developing and applying individual-based models (IBMs) based on a regional ocean circulation model and an IPCC climate change scenario. Despite the greater uncertainty, our two IBMs projected that, by the 2030s, the strengthened Tsushima warm current in the Korea Strait and the East Sea, driven by global warming, and the subsequent confinement of the relatively cold water masses within the Yellow Sea will decrease larval anchovy biomass in the Yellow Sea, but will increase it in the Korea Strait and the East Sea. The decreasing trend of anchovy biomass in the Yellow Sea was reproduced by our models, but further validation and enhancement of the models is required together with extended ichthyoplankton surveys to understand and reliably project range shifts of anchovy and the impacts such range shifts will have on the marine ecosystems and fisheries in the region.     

西藏嘎拉勒铜金矿床地质特征与控矿条件分析

嘎拉勒铜金矿床位于冈底斯成矿带西段北缘,是近年来该区域发现的一个重要的典型镁质矽卡岩型铜金矿床。本文在矿区大比例尺地质填图基础上,结合前人研究资料,对该矿床地质特征和控矿条件进行了系统阐述和分析。矿区内出露地层主要为下白垩统捷嘎组白云岩和白云质灰岩,其下伏为下白垩统郎久组砂岩、粉砂岩和流纹质-英安质火山岩及火山碎屑岩。矿区内至少发生了3期构造变形,第1期形成北西向褶皱和北东向张性横断层,第2期形成北东向褶皱、北东向压性纵断层和北西向小型张性横断层,第3期形成近南北向正断层。区内自早到晚侵入有燕山晚期斑状石英闪长岩、闪长玢岩、石英闪长岩、花岗闪长岩和花岗斑岩。在石英闪长岩和花岗闪长岩与捷嘎组白云岩和白云质灰岩接触带附近形成典型镁质矽卡岩,包括早、晚两个阶段,早阶段形成由橄榄石、粒硅镁石和少量尖晶石、石榴子石、透辉石组成的干矽卡岩,晚阶段形成由蛇纹石、金云母和少量绿帘石组成的湿矽卡岩,叠加在干矽卡岩之上或其外侧,构成自岩体向外的橄榄石+尖晶石+粒硅镁石±石榴石±金云母带、金云母+蛇纹石±橄榄石±石榴石±透辉石带、蛇纹石+金云母+绿帘石±透辉石带、蛇纹石±金云母化大理岩带。矿体呈层状、似层状、团块状及不规则状主要产于蛇纹石+金云母化带内,金属矿物主要有磁铁矿、黄铁矿、黄铜矿、斑铜矿、辉铜矿、自然金等,伴有硅化、绿泥石化和碳酸盐化。成矿作用与花岗闪长岩和石英闪长岩的侵入活动密切相关,主要受北东和北西向褶皱及相关断裂控制,矽卡岩化受捷嘎组中部纹层状白云岩和砂质白云岩等有利岩性控制,矿体就位于矽卡岩带的高渗透率部位。     

青海引胜沟岩体的锆石U-Pb年代学、地球化学特征及其地质意义

祁连造山带发育有大面积的中-酸性侵入岩。引胜沟花岗质岩体位于中祁连造山带东段,主要岩性为花岗闪长岩。LA-MC-ICPMS锆石U-Pb测年结果分别为(436.9±5.3)Ma和(453.5±6.9)Ma,表明岩体是早志留世-中奥陶世岩浆活动的产物。根据岩体的地球化学特征不同可分为两组岩石:一组岩石特征为高SiO2,w(SiO2)为71.23%~73.65%,高A/CNK值(1.19~1.39);镁铁(MF)指数为90~92,长英质(FL)指数为87~92,显示岩浆结晶分异程度较高;w(∑REE)=22.88×10-6~40.65×10-6,LREE/HREE比值为1.8~2.63,(Ce/Yb)N比值为1.36~1.95;δEu=0.06~0.49,平均为0.27,负Eu异常较为明显。另一组岩石特征为低SiO2,w(SiO2)为62.35%~63.73%,低A/CNK值(0.93~1.05);镁铁(MF)指数为81~82,长英质(FL)指数为61~65,与第一组岩石相比,岩浆结晶分异程度较低;w(∑REE)=94.10×10-6~235.50×10-6,(Ce/Yb)N比值为1.43~10.49,δEu=0.82~0.92。岩石地球化学特征表明,引胜沟花岗质岩体是祁连造山带由俯冲向碰撞转换的构造环境下产生的,具有壳幔混合的特点。     

基于核半监督判别分析的高光谱影像特征提取

针对高光谱影像特征提取中地物类别训练样本获取代价较高的情况,在线性判别分析的基础上,结合核方法和半监督学习理论,提出了一种基于核半监督判别分析(KSDA)的高光谱影像特征提取方法。该方法同时利用少量已知类别和大量未知类别样本数据进行模型的学习和训练。通过OMIS高光谱影像数据实验表明:在少量已知类别训练样本的条件下,经KSDA特征提取的样本数据在特征空间中能更好地聚集成团,且类别之间的距离较大,增加了类别之间的可分性,得到了较高的分类精度;同时,提取的特征影像能够较好地区分各种地物类别。     

人类活动对鄱阳湖泥沙收支平衡的影响

以鄱阳湖流域内的赣江、抚河、信江、饶河和修水（五河）和鄱阳湖为研究对象,利用水文控制站的水文资料,分析了各流域内主要河流的入湖泥沙和鄱阳湖出湖泥沙特征,对鄱阳湖泥沙收支平衡进行了分析。结果表明：① 1955~2010年五河总入湖泥沙811.69 Mt,其中赣江（占59.7%）>信江（占13.7%）>修河（占10.2%）>抚河（占9.7%）>饶河（占6.7%）;② 径流量是影响入湖输沙量的最主要因素,入湖泥沙与入湖径流的季节特征一致;③ 水库的蓄水拦沙作用是五河入湖泥沙下降的主要原因,但水库对入湖泥沙的影响强度与水库库容和集水区的植被覆盖状况有关;植被覆盖变化对赣江、抚河、饶河和修河的入湖输沙量的影响明显;④ 1955~2010年,鄱阳湖总出湖泥沙560.10 Mt,其中1955~2000年出湖泥沙量呈降低趋势,但受鄱阳湖采砂影响,2001年以来出湖泥沙显著增加;丰水季长江水对鄱阳湖的顶托和倒灌,使出湖泥沙与出湖径流在时间上不同步;三峡工程的运行改变了（长）江（鄱阳）湖之间的水动力关系,长江倒灌泥沙显著减少;⑤ 受鄱阳湖采砂的影响,鄱阳湖泥沙平衡系统由净沉积转变为净侵蚀,1955~2000年入湖泥沙大于出湖泥沙,年均泥沙沉积约为1.41 mm;2001~2010年出湖泥沙大于入湖泥沙,加上采砂输出沙量,2001~2010年鄱阳湖泥沙净减少2 213.65 Mt。     

基于CIMISS的区域灾害性天气实时监测与报警系统的设计与实现

基于CIMISS提供的统一数据环境,结合当前气象防灾减灾服务需求,设计出一个集约化的全自动气象灾害监测报警系统,能够直接向各类用户个人提供定制化的实时灾害性天气信息服务,并使用户能够随时随地通过移动设备或台式电脑了解灾害性天气的发生和发展详细情况。本文从系统功能结构、信息收集与处理流程、灾害性天气报警时机判断及实况信息生成算法等方面,对该系统的设计内容及其实现方式进行了介绍。