Genetic Analogy Between Sediment—Hosted Gold Deposits and Sediment—Hosted Copper Deposits in Southwest China

The sediment-hosted copper deposits according to the authors‘ study were formed from connate formation water during the post-sedimentary or diagenetic stage while the sediment-hosted disseminated gold deposits are unanimously considered to be of post-sedimentary hydrothermal origin.Therefore,apart from their own individulities.These two types of deposits must share some characters in common.Comparisons are attempted,in this paper,between the sediment-hosted copper deposits in southwest China and the Triassic sediment-hosted disseminated gold deposits in the Yunnan-Guizhou-Guangxi Triangle in terms of geological and geochemical features.     

高空冷涡背景下飞机积冰特征和机制的探测研究

飞机结冰可能引发严重飞行事故。为了了解飞机在冷涡背景下自然结冰的特征和机制,2021年5月,内蒙古呼伦贝尔市人工增雨作业人员使用Y-12运输机在高空冷涡天气系统中进行了7个架次飞机结冰探测试验,其中出现中度和重度飞机积冰各2个架次,对飞机积冰探测的环境气象条件进行了讨论,着重分析了5月31日2个架次重度飞机积冰过程取得的DMT粒子测量数据。结果表明：飞机平飞海拔高度为3.5～4.2 km,环境温度为-8～-4℃时,重度飞机积冰出现在冷涡东南部水汽饱和区中;测量的过冷水含量在高值时段的平均值达到0.25～1.04 g·m-3,平均有效直径为15～100 μm的粒子浓度显著偏高,达到100~200个·cm-3,高浓度的过冷水含量导致飞机外壳出现瞬时快速积冰。简述了高空冷涡东南象限航线上的云层粒子图像和云粒子增长方式,讨论了高空冷涡东南象限的大气结冰条件。     

Geological and C–O–S–Pb–Sr isotopic constraints on the origin of the Qingshan carbonate-hosted Pb–Zn deposit,Southwest China

Located in the western Yangtze Block, the Qingshan Pb–Zn deposit, part of the Sichuan–Yunnan–Guizhou Pb–Zn metallogenic province, contains 0.3 million tonnes of 9.86 wt.% Pb and 22.27 wt.% Zn. Ore bodies are hosted in Carboniferous and Permian carbonate rocks, structurally controlled by the Weining–Shuicheng anticline and its intraformational faults. Ores composed of sphalerite, galena, pyrite, dolomite, and calcite occur as massive, brecciated, veinlets, and disseminations in dolomitic limestones.

The C–O isotope compositions of hydrothermal calcite and S–Pb–Sr isotope compositions of Qingshan sulphide minerals were analysed in order to trace the sources of reduced sulphur and metals for the Pb–Zn deposit. δ¹³C_PDB and δ¹⁸O_SMOW values of calcite range from –5.0‰ to –3.4‰ and +18.9‰ to +19.6‰, respectively, and fall in the field between mantle and marine carbonate rocks. They display a negative correlation, suggesting that CO₂ in the hydrothermal fluid had a mixed origin of mantle, marine carbonate rocks, and sedimentary organic matter. δ³⁴S values of sulphide minerals range from +10.7‰ to +19.6‰, similar to Devonian-to-Permian seawater sulphate (+20‰ to +35‰) and evaporite rocks (+23‰ to +28‰) in Carboniferous-to-Permian strata, suggesting that the reduced sulphur in hydrothermal fluids was derived from host-strata evaporites. Ores and sulphide minerals have homogeneous and low radiogenic Pb isotope compositions (²⁰⁶Pb/²⁰⁴Pb = 18.561 to 18.768, ²⁰⁷Pb/²⁰⁴Pb = 15.701 to 15.920, and ²⁰⁸Pb/²⁰⁴Pb = 38.831 to 39.641) that plot in the upper crust Pb evolution curve, and are similar to those of Devonian-to-Permian carbonate rocks. Pb isotope compositions suggest derivation of Pb metal from the host rocks. ⁸⁷Sr/⁸⁶Sr ratios of sphalerite range from 0.7107 to 0.7136 and (⁸⁷Sr/⁸⁶Sr)_200Ma ratios range from 0.7099 to 0.7126, higher than Sinian-to-Permian sedimentary rocks and Permian Emeishan flood basalts, but lower than Proterozoic basement rocks. This indicates that the ore strontium has a mixture source of the older basement rocks and the younger cover sequence. C–O–S–Pb–Sr isotope compositions of the Qingshan Pb–Zn deposit indicate a mixed origin of the ore-forming fluids and metals.     

涡激振动实验中的流速增大装置研发与性能研究

拖曳水池中进行立管涡激振动实验时,为了保证采样时间长度,难以达到较高的Re数。流速增大装置可以在不提高拖车车速的情况下增大立管外的流速。利用这种流速增大装置还可实现流速分层流场中细长柔性立管涡激振动实验。经过对流速增大装置中的进流段曲线进行优选,发现Witozinsky曲线的总体性能最好。在对流速增大装置进行水池实验和数值模拟后,发现流速增大区域的流速增大倍数接近进流段收缩比,流速增大区域流场比较稳定、均匀,流速增大装置对其外的流场影响很小。此流速增大装置不但可应用于拖曳水池中的立管涡激振动实验,还可以应用于对流速要求较高的水下航行体的水池试验,如鱼雷、水下机器人等。     

长、短东移路径暖季高影响高原涡动力结构特征的对比分析

利用1998～2018年5～9月NCEP/NCAR全球分析数据、大气观测资料、青藏高原低涡切变线年鉴,采用伴随低涡活动的动态合成方法比较分析了准平直东移长、短路径暖季高影响高原涡的结构特征,进一步讨论了长、短路径涡的强度与其结构的关系,从而说明长、短路径涡的演变某种程度上是由低涡自身的结构决定的。其主要结论如下：（1）长、短路径涡相同的结构特征有：生成时是浅薄的天气系统、移出高原后发展为较深厚的天气系统;在不同的活动阶段低涡的涡度变化趋势一致。（2）长、短路径涡的结构特征明显差别表现在：加强时,长路径涡所伴的正涡度柱比短路径涡深厚,上升运动柱比短路径涡强;长路径涡所伴的正涡度柱随高度升高向北倾斜、涡度值上小下大,不同于短路径涡呈对称分布、涡度值上大下小;长路径涡所伴的南风中心位置比短路径涡偏东,东、西风交汇位置比短路径涡更偏南、更强;长路径涡加强时涡区上空正涡度平流中心位置比移出时下降、强度加强,且持续时间长、向东偏离低涡,短路径涡则相反。（3）长、短路径涡在不同演变中,低涡的强度变化是由输入涡区的正涡度平流支撑的。长、短路径涡加强时的结构特征差异体现了长路径涡蕰含涡度增加的垂直输送机制和正涡度平流强迫上升运动增强而使低涡加强的动力机制。     

2011年中国4次成灾性气候异常及其原因分析

为了研究地震与气候异常的关系,从地震活动的角度对2011年发生在我国的4次成灾性气候异常进行了分析.结果表明,2011年长江中游春、夏季大旱的直接原因是3月24日发生在缅甸的7.2级地震;长江中下游6月上旬出现旱涝急转则与3月11日日本东部的9.0级地震及缅甸地震密不可分;鄂赣交界发生的4.6级地震对黄河中游秋汛的影响最为明显,这是“震侧强涡”造成的结果;2012年1月贵州冻雨较多也是受到印度锡金和我国东海两个地震形成的“拍涡”影响,这表明地震活动是影响天气、气候变化的可能原因之一.     

Link between convection and meridional gradient of sea surface temperature in the Bay of Bengal

We use daily satellite estimates of sea surface temperature (SST) and rainfall during 1998–2005 to show that onset of convection over the central Bay of Bengal (88–92°E, 14–18°N) during the core summer monsoon (mid-May to September) is linked to the meridional gradient of SST in the bay. The SST gradient was computed between two boxes in the northern (88–92°E, 18–22°N) and southern (82–88°E, 4–8°N) bay; the latter is the area of the cold tongue in the bay linked to the Summer Monsoon Current. Convection over central bay followed the SST difference between the northern and southern bay (ΔT) exceeding 0.75°C in 28 cases. There was no instance of ΔT exceeding this threshold without a burst in convection. There were, however, five instances of convection occurring without this SST gradient. Long rainfall events (events lasting more than a week) were associated with an SST event (ΔT ≥ 0.75°C); rainfall events tended to be short when not associated with an SST event. The SST gradient was important for the onset of convection, but not for its persistence: convection often persisted for several days even after the SST gradient weakened. The lag between ΔT exceeding 0.75°C and the onset of convection was 0–18 days, but the lag histogram peaked at one week. In 75% of the 28 cases, convection occurred within a week of ΔT exceeding the threshold of 0.75°C. The northern bay SST, T _N , contributed more to ΔT, but it was a weaker criterion for convection than the SST gradient. A sensitivity analysis showed that the corresponding threshold for T _N was 29°C. We hypothesise that the excess heating (∼1°C above the threshold for deep convection) required in the northern bay to trigger convection is because this excess in SST is what is required to establish the critical SST gradient.     

两次东风带高空冷涡强对流天气对比分析

利用常规气象站、自动站、NCEP/NCAR（美国国家环境预报中心/国家大气研究中心）的全球预报系统（GFS）分析资料、多普勒雷达和卫星等多种资料,对2015年7月29日和2018年7月14日两次过程对比分析后发现：两次过程在200 hPa 上均存在一个东风带涡旋,500 hPa是类似东风波的系统,850 hPa处于副热带高压环流中,因此这两次过程是在东风带高空冷涡背景下发生的。处于东风带中的涡旋系统与台风、东风波等系统显著不同,其垂直方向上并不深厚,主要位于对流层中上层,湿度较高但温度较低,系统本身不像台风或东风波那样会发生大风、暴雨等强烈天气。2015年7月29日中午在浙闽沿海因海洋、陆地风向风速差异以及高低层之间风向辐合等因素影响下,形成了东、西风之间的中尺度辐合线,随后中尺度辐合线触发或加强了对流天气;而2018年7月14日过程虽然具备了对流潜势,但由于缺乏低层的触发机制,最终没有发生强对流。高层冷涡西进时,冷涡前进方向高层的辐散式旋转特性增强了中低层的上升运动,有助于对流天气加强,这与西风带天气过程有明显差异,会给强对流的预报预警造成较大困难,应特别关注。