Epithermal deposits in North Xinjiang, NW China

The North Xinjiang region (NW China) is an important part of the Central Asia Orogenic Belt, situated at the junction of Siberia, Tarim and Kazakhstan plates. It is an area characterized by multiple stages of Phanerozoic continental growth, during which several porphyry and epithermal systems were formed. The relationship of these mineral systems to the geodynamic evolution of the region has not yet been well understood. In this paper, we list the main geological characteristics of 21 significant epithermal precious and base metal deposits in North Xinjiang, and classify them into high-sulfidation and low-sulfidation styles, with the latter being predominant. We have selected seven epithermal deposits representing different styles formed under different tectonic regimes and discuss their geology and geochemistry in some detail. The deposit-scale geology and geochemistry of epithermal systems in North Xinjiang are essentially similar to those in other parts of the world. All epithermal deposits in North Xinjiang are hosted in volcanic rocks with ages ranging from Devonian to Triassic, with the Early Carboniferous volcanic sequences being the most important, followed by the Permian and Triassic. The Devonian–Early Carboniferous host rocks belong to the calc-alkaline series that developed in pre-collisional arc-back-arc basin systems; whereas the Permian–Triassic host volcanic rocks of shoshonite series formed in post-subduction regimes. Available isotopic ages of these epithermal systems cluster in two periods: Early Carboniferous (>320?Ma) and Late Carboniferous–Triassic (320–220?Ma), reflecting two metallogenic episodes that occurred during subduction-related accretion and post-subduction collision regimes, respectively. Accordingly, three groups of epithermal deposits in North Xinjiang can be recognized as (1) pre-collisional deposits without or with negligible collisional-related modification, (2) deposits formed in collision regime and (3) ore systems strongly overprinted by fluid flow in post-subduction collision regime.     

分区上异点校正法在干旱地区1:5万地球化学异常圈定中的应用:以我国西北某地区为例

我国西北地区具有独特的干旱荒漠戈壁残山景观,风成砂、黄土硬壳以及下伏的膏岩层与岩屑层共同构成了浅层地表土壤的基本结构.以西北某干旱地区为例,针对剥蚀程度高且元素富集不明显的干旱荒漠区,提出了分区上异点校正法.该方法是一种建立在非常规统计学基础上的数据处理方法,直接通过某种规则将各个分区的上异点调整到统一水平上,使得每个...     

基于四维灾体模型的浙江省气象灾害损失年景评价

应用浙江省气象灾情统计年鉴资料,运用四维灾体评估模型,对浙江省的气象灾害损失进行科学评估。浙江省2003—2017年灾害损失年景评价分析结果显示,2004年和2005年为气象灾害损失明显偏重年景,进入2010年以来,2013年为年景最差年份;台风灾害损失在每年浙江省气象灾害损失年景评价中具有非常重要的作用,重大台风事件易造成气象灾害偏重或明显偏重的损失年景。评估结果表明,四维灾体模型下的气象灾害评估较为科学客观。     

Cloud Variations under Subtropical High Conditions

The cloud variations under subtropical high(STH) conditions during summers over a ten-year period are studied using combined data from the International Satellite Cloud Climatology Project and the National Centers for Environmental Prediction.The results reveal that clouds mainly experience an isolated evolution in the STHs,which is designated in this study by the 1540 gpm geopotential lines at 850 hPa.In the STH domain throughout the Northern Hemisphere,the average amount of total clouds exceeds 30%.Low clouds dominate in the STH domain,contributing over 60%of total cloud amount within the Pacific subtropical high and over 40%within the Atlantic subtropical high.The prevalence of low clouds in above regions is determined by the circulation pattern around 150°-180°E and 850 hPa,which suppresses both the upward development of the cloud tops and the water vapor divergences near the surface.Furthermore,clouds present great geographical incoherence within the STH domain.In the eastern STHs,the amount of middle and low clouds increases to peak in the early morning and decreases to a trough in the afternoon,while the amount of high clouds remains stable throughout the day.Conversely,in the western STHs,the diurnal amplitude of low and middle clouds is less than three,while high clouds dramatically reach the maximum in the afternoon and drop to the minimum in the evening.Among the nine cloud categories,stratocumulus clouds with greater optical thickness account for the most under STH conditions,no matter their occurrence or amount,causing more shortwave cloud radiative forcing to cool the local atmosphere and surface as a consequence.     

中国海相油气田勘探实例之十三 塔里木盆地东河塘海相砂岩油田勘探与发现

东河塘油田位于新疆库车县,构造上隶属于塔里木盆地塔北隆起轮台凸起东河塘断裂构造带,是我国发现的第一个高产高丰度海相砂岩油田,它的发现是中国海相砂岩油气勘探理论和实践的一次重大突破。油田发现于1990年7月,至1994年探明石油地质储量3323.13×104t,天然气地质储量15.5×108m3,至2009年底累计产原油825.75×104t。石炭系东河砂岩油藏是东河塘油田的主体,其储层东河砂岩段是一套滨岸相砂体,具有厚度巨大、埋深大、储集性能好的特点;其油藏类型为块状底水背斜油藏,产能高,储量丰度高。论述了东河塘油田勘探与发现的历程,剖析了取得勘探成功的实践认识与意义。     

Extreme precipitation events identified using detrended fluctuation analysis (DFA) in Anhui,China

Extreme weather events include unusual, severe or unseasonal weather, and weather at the extremes of the historical distribution. They have become more frequent and intense under global warming, especially in mid-latitude areas. They bring about great agricultural and economic losses. It is important to define the threshold of extreme weather event because it is the starting point of extreme weather event research, though it has been of seldom concern. Taking extreme precipitation events in Anhui, China as an example, the detrended fluctuation analysis (DFA) method is introduced to define the threshold of extreme weather events. Based on it, the spatial and temporal distributions of extreme precipitation events are analyzed. Compared to the traditional percentile method, DFA is based on the long-term correlation of time series. Thresholds calculated by DFA are much higher than the 99th percentile and the values are higher in the south and lower in the north. This spatial pattern is similar to the annual precipitation spatial pattern. There is an obvious increasing trend in the number of days with extreme precipitation, especially after the 1980s. This observation supports the point that more extreme events happen under global warming.     

青海牧区近10年牧草产量变化与气象条件的关系

利用DPS统计中的相关、回归等方法分析近10年青海高原牧区5站点牧草产量变化与气象因子的关系,并建立了牧草产量的气象条件多元回归拟合模型。结果表明：近10年来牧草产量的年最高值河南、甘德总体呈下降趋势,曲麻莱、海北、兴海总体呈上升趋势;5站点牧草产量5月变幅最大为兴海,变幅最小的为海北,6—8月变幅最大的是曲麻莱,变幅最小的是海北;5站点8月牧草产量形成期总体上日照充足,降水除河南阶段性较充沛外,其余受限制,温度除河南在牧草生长季内当光温出现匹配不当时呈负相关外,其余均受限制;气象因子与5站点年最高牧草产量的拟合模式拟合效果较好,均可通过0.01检验。     

融机器学习与WRF大气模式的PM2.5预报方法

针对当前我国重污染天气实时的空气质量预报问题,该文提出了一种融合随机森林算法与WRF大气模式的PM2.5浓度实时预报方法。该方法结合了北京市地面空气质量监测数据和WRF气象数据进行分析,将高层大气状态(如逆温层高度等)融入了预报模型中,建立了0~72h的PM2.5浓度实时预报模型。实验证明,该模型能够对0~72h单站点的PM2.5浓度进行较高精度的实时预报,且在24~72h的长时预报结果上较基于地面空气污染物数据与地表气象站数据的预报方法精度有明显提升,即该方法可以更好地模拟大气物理化学状态,从而更为精准地进行长时PM2.5浓度预报。     

典型湖泊天然有机质与四环素的相互作用

采用荧光滴定法研究四环素(tetracycline,TC)与太湖溶解性有机质(dissolved organic matter,DOM)和玄武湖DOM的相互作用.三维荧光光谱结合平行因子分析显示,2个湖泊的DOM含有3个荧光组分:类富里酸组分C1、类色氨酸组分C2和类络氨酸组分C3.其中C2的荧光强度远高于C1和C3,是DOM的主要荧光组成.3个荧光组分与TC发生了不同程度的静态猝灭,特别当TC浓度为45.5μmol/L时,类蛋白组分的荧光强度完全被猝灭(100%),并且猝灭作用改变了DOM分子的微环境极性.同步荧光光谱联合二维相关图谱进一步表明类色氨酸组分优先和TC发生猝灭作用,其次为类络氨酸组分和类富里酸组分.Ryan-Weber方程适于拟合DOM与TC的猝灭过程,2个湖泊的DOM中3个荧光组分的络合常数lg K值范围为5.05~5.85,大小顺序为C2C3C1.因此,类蛋白组分为主的DOM对TC的络合作用大于类腐殖组分为主的DOM,影响抗生素在湖泊水体中的生物有效性和生态毒性.     

近百年来湖泊有机碳与无机碳埋藏响应流域开发的协同变化——以石林喀斯特地区为例

有机碳和无机碳的流域输出是湖泊碳埋藏的重要驱动因子,而喀斯特地区无机碳循环具有反应迅速且对人类活动影响敏感的特点.在流域开发持续增强的背景下,喀斯特地区湖泊有机碳和无机碳的来源、含量与埋藏通量可能会出现同步变化的协同模式.本文以云南省石林喀斯特地区流域土地利用类型不同的两个中型湖泊(长湖、月湖)开展对比分析,通过对沉积物钻孔的土壤侵蚀强度(磁化率)、流域外源输入(C:N比值)、水动力(粒度)、营养盐(总氮、总磷)、藻类生产力(叶绿素色素)等代用指标的分析,结合监测数据和历史资料重建了两个湖泊环境变化的近百年历史,并定量识别了有机碳和无机碳埋藏响应流域开发的变化特征与协同模式.沉积物磁化率和C:N比值结果揭示了流域地表侵蚀和外源输入的阶段性特征,同时总氮和总磷含量记录了长湖和月湖营养水平上升的长期模式.在流域森林覆被较高(33.43%)的长湖中,全岩和有机质C:N比值分别与磁化率信号呈显著正相关(r=0.95和0.89,P<0.001),且与无机碳和有机碳含量呈显著负相关(r=-0.94,P<0.001和r=-0.52,P=0.01),反映了森林植被退化时流域碳输出的减少对沉...