广西田东县那矿金矿区地质与地球化学特征及找矿方向     

黄美 《地质与勘探》2016,52(5):854-864

广西田东县那矿金矿位于滇黔桂金三角,属于卡林型金矿。本文在对那矿金矿区进行1∶10000地质填图的基础上,基本上查明了其成矿地质背景,结合1∶10000土壤地球化学测量,选取Au、As、Sb三种元素为成矿指示元素。通过土壤地球化学数据分析,对矿区内指示元素异常的特征、分布与地质现象进行对比分析,进行异常解释评价。研究结果显示:那矿金矿区中三叠统百逢组中上部粉砂质泥岩、泥岩、泥质粉砂岩是赋矿层位;坡表谷背斜与坡表谷断裂的复合部位为成矿有利部位;硅化、(褐)黄铁矿化、毒砂矿化、高岭石化、绢云母化、碳酸盐岩化等蚀变为金的矿化标志;圈定的Ⅰ号异常带是矿致异常,其Au元素异常规模大、品位高,是该区找矿的重点靶区。  相似文献   

Effects of low- to high-angle normal faults on sedimentary architectures in the Eocene Wenchang Formation,Enping Sag,Pearl River Mouth Basin,South China Sea     

Q. H. Liu  Y. Shu  X. M. Zhu  X. H. Yang  M. Tan 《Australian Journal of Earth Sciences》2016,63(7):903-922

The effects of low- to high-angle (>30°) normal faults on sedimentary architectural units in the Eocene Wenchang Formation, Enping Sag, Pearl River Mouth Basin (PRMB), South China Sea were investigated utilising a high-quality 3D seismic data set and restored paleogeomorphology. It has been shown that sequence stratigraphic units and sedimentary architecture are significantly controlled by the low- to high-angle normal faults. The Wenchang Formation, a second-order sequence, can be subdivided into two para-second-sequences (the Lower and Upper Wenchang sequences, E₂W^L and E₂W^U) and seven third-order sequences (from base to top: SQ1～SQ7). The low-angle fault confined sequence architecture of the Wenchang Formation is mainly characterised by lateral stacking with the ratio of the vertical subsidence (V) to horizontal slip (H) being reduced from 1/2 for E₂W^L to 1/6 for E₂W^U. In contrast, the high-angle fault confined sequence is characterised by vertical stacking with the ratio of V/H close to 1 for sequences SQ1 to SQ7. In the 3D seismic area, the features of sediment-dispersal pattern were interpreted based on an integrated analysis of paleogeomorphology, seismic reflection characteristics, stratal thickness distribution and multiple attribute clustering. The results show that the large-scale fan delta, belt-shape lacustrine deposit and bird-foot braided delta systems mainly developed in the low-angle fault confined sequences, whereas small-scale fan delta, rhombus-shaped lacustrine deposit and lobe-shaped braided delta systems inherited tectono-sedimentary architectures in the high-angle fault confined sequences.  相似文献   

Origin of the alkali tonsteins from southwest China: Implications for alkaline magmatism associated with the waning stages of the Emeishan Large Igneous Province     

L. Zhao  I. Graham 《Australian Journal of Earth Sciences》2016,63(1):123-128

A unique type of Nb–Zr–REE–Ga-enriched alkali tonstein of pyroclastic origin occurs exclusively within the late Permian coal measures of southwest China. The alkali tonsteins are located within the lowest Xuanwei or Longtan formations of Wuchiapingian age, indicating that their age is later than the main episode of Emeishan Large Igneous Province (ELIP) magmatism. The alkali tonsteins have intermediate–felsic Al₂O₃/TiO₂ values (12.6–34.2, mean 22.0), light rare earth element-enriched chondrite-normalised patterns, negative δEu and incompatible element ratios similar to those of ELIP alkaline Nb–Ta-enriched syenites. All available evidence shows that the alkali tonsteins from southwest China originated from coeval ELIP alkaline magmatism. The enrichment of Nb–Zr–REE–Ga in alkali tonsteins is derived from the ELIP alkaline Nb–Ta-enriched volcanic ashes and may represent the last stage of mineralisation associated with the Emeishan mantle plume activity.  相似文献   

Influence of internal decadal variability on the summer rainfall in Eastern China as simulated by CCSM4     

Yali Zhu  Tao Wang  Jiehua Ma 《大气科学进展》2016,33(6):706-714

The combined impact of the Pacific Decadal Oscillation(PDO) and Atlantic Multidecadal Oscillation(AMO) on the summer rainfall in eastern China was investigated using CCSM4. The strongest signals occur with the combination of a positive PDO and a negative AMO(+PDO- AMO), as well as a negative PDO and a positive AMO(-PDO + AMO). For the +PDO- AMO set, significant positive rainfall anomalies occur over the lower reaches of the Yangtze River valley(YR),when the East Asian summer monsoon becomes weaker, while the East Asian westerly jet stream becomes stronger, and ascending motion over the YR becomes enhanced due to the jet-related secondary circulation. Contrary anomalies occur over East Asia for the-PDO + AMO set. The influence of these two combinations of PDO and AMO on the summer rainfall in eastern China can also be observed in the two interdecadal rainfall changes in eastern China in the late 1970 s and late 1990 s.  相似文献   

中国南海夏季风强、弱年多尺度相互作用能量学特征   总被引：1，自引：0，他引：1  

杨悦  徐邦琪  何金海 《气象学报》2016,74(4):556-571

中国南海夏季风为东亚季风的主要系统之一,其具有多重尺度特征,除季节平均环流场外,低频（季节内振荡）和高频（天气尺度）扰动也十分活跃,各尺度系统存在明显的年际变化。该研究使用ERA-Interim和NCEP/NCAR两套再分析资料,从季风平均动能（MKE）诊断的角度出发,探讨了1979-2010年中国南海夏季风环流年际变化的能量来源及其和扰动场的相互作用过程。结果表明:中国南海夏季风对流活跃年份,中国南海南部（12°N以南）及中南半岛一带为季风平均动能显著增强区,此与南亚季风区西风急流的增强并向东延伸有关;中国南海北部（12°N以北）及西太平洋为气旋性环流盘踞,季风槽加深。中国南海南部季风平均动能增强的能量源自于扰动动量通量与平均环流的相互作用,强季风年,平均环流失去较少的动能给扰动场（亦即平均环流保留较多的动能）。通过进一步探讨高频（<10 d）及低频（10-90 d）扰动场与平均环流不同分量的（散度、涡度、风垂直切变）相互作用过程,发现季风平均动能的增长主要来自于<10 d扰动与季风平均散度和涡度的相互作用。中国南海北部季风槽区季风平均动能的维持来自于大气热源和平均上升运动的相互作用,但同时有较多的季风平均动能向扰动动能转换,有利于扰动的成长。因此,强季风年,中国南海北部热带气旋生成数目增多,夏季北传的季节内振荡也增强,导致中国南部沿海及华南地区出现较多的灾害天气。   相似文献   

中国区域性极端降水事件及人口经济暴露度研究   总被引：4，自引：1，他引：3  

景丞  姜彤  王艳君  陈静  蹇东南  罗岚心  苏布达 《气象学报》2016,74(4):572-582

基于中国1960-2014年771个气象站的逐日降水资料,选取有效降水序列95百分位数作为极端降水阈值,将既定持续时间尺度和连续面积上超过阈值的降水事件定义为区域性极端降水事件。采用强度-面积-持续时间（Intensity-Area-Duration,IAD）法,根据极端降水事件空间和时间上的连续性特征,对不同持续时间的区域性极端降水事件演变趋势及暴露于极端降水事件下的人口和国内生产总值进行研究。结果表明:（1）相对强度最大的区域性极端降水事件主要集中在1960-1968、1991-1999和2006-2013年3个时段;（2）区域性极端降水事件最强中心主要分布在长江以南和东北地区,发生在北方的多为单日极端降水,南方多为持续多日的极端降水;（3）1960-2014年区域性极端降水事件影响面积有所增大,相对强度变化不明显;（4）暴露于极端降水事件影响区域内的人口和国内生产总值均呈显著增大趋势,暴露人口最多的年份在1983年,达到2408万人/d,暴露国内生产总值最多的年份在1998年,达到20亿元/d。   相似文献   

A timescale decomposed threshold regression downscaling approach to forecasting South China early summer rainfall     

Linye Song  Wansuo Duan  Yun Li  Jiangyu Mao 《大气科学进展》2016,33(9):1071-7084

A timescale decomposed threshold regression(TSDTR) downscaling approach to forecasting South China early summer rainfall(SCESR) is described by using long-term observed station rainfall data and NOAA ERSST data. It makes use of two distinct regression downscaling models corresponding to the interannual and interdecadal rainfall variability of SCESR.The two models are developed based on the partial least squares(PLS) regression technique, linking SCESR to SST modes in preceding months on both interannual and interdecadal timescales. Specifically, using the datasets in the calibration period 1915–84, the variability of SCESR and SST are decomposed into interannual and interdecadal components. On the interannual timescale, a threshold PLS regression model is fitted to interannual components of SCESR and March SST patterns by taking account of the modulation of negative and positive phases of the Pacific Decadal Oscillation(PDO). On the interdecadal timescale, a standard PLS regression model is fitted to the relationship between SCESR and preceding November SST patterns. The total rainfall prediction is obtained by the sum of the outputs from both the interannual and interdecadal models. Results show that the TSDTR downscaling approach achieves reasonable skill in predicting the observed rainfall in the validation period 1985–2006, compared to other simpler approaches. This study suggests that the TSDTR approach,considering different interannual SCESR-SST relationships under the modulation of PDO phases, as well as the interdecadal variability of SCESR associated with SST patterns, may provide a new perspective to improve climate predictions.  相似文献   

东北地区春季首场透雨的变化特征及与青藏高原地面加热场强度的关系   总被引：2，自引：1，他引：1  

徐士琦  李栋梁 《气象》2016,42(3):271-279

利用1958—2012年4—5月东北地区(39°~55°N、118°~135°E)101个站点逐日降水资料、青藏高原地区(25°~40°N、73.75°~103.75°E)JRA-55的地面感热和潜热通量月平均再分析资料以及NCEP/NCAR-I大气环流场的月平均再分析资料,分析了春播期首场透雨出现日期的时空变化特征及其与透雨量和播种期降水量间的关系,以及对青藏高原地面加热场强度异常的响应及其可能机制。结果表明:透雨日期自1958年以来在东北地区的西北和东南大部分区域呈现略微偏晚的趋势;中部有略微偏早的趋势。春播期首场透雨出现时间偏早(晚)的地方,首场透雨量小(大),春播期总降水量多(少)。同时,4月青藏高原地面加热场强度增强(减弱),有利于(不利于)来自北方的冷空气和南方的暖湿气流在东北上空交汇,且上升气流增强(减弱),水汽输送充沛(减少),导致该地区春季首场透雨出现的时间偏早(晚)。  相似文献   

淮河流域夏季降水异常与若干气候因子的关系   总被引：5，自引：2，他引：3       下载免费PDF全文

王月  张强  顾西辉  孔冬冬 《应用气象学报》2016,27(1):67-74

基于旋转经验正交函数分解 (REOF) 方法探讨淮河流域1961—2010年夏季降水与厄尔尼诺/南方涛动 (ENSO)、北大西洋涛动 (NAO)、印度洋偶极子 (IOD)、太平洋年代际振荡 (PDO) 之间的关系,并进一步分析各气候因子不同位相单独以及联合对淮河流域夏季降水的影响。结果表明:淮河流域夏季降水与ENSO,PDO,NAO,IOD等气候因子具有较稳定的相关性,其中,PDO和IOD是影响淮河流域夏季降水的关键因子,且PDO与夏季降水呈显著负相关关系;各气候因子的冷暖位相单独及联合对淮河流域夏季降水的影响不同,PDO的冷期以及NAO,IOD冷位相使流域北部的夏季降水量呈显著增加趋势,PDO分别联合ENSO,NAO和IOD的冷、暖位相对流域北部地区和淮河上游地区的夏季降水影响显著。  相似文献   

IEC的风机选型参数估算方法在中国的适用性研究     

黄林宏  宋丽莉  李刚  王丙兰  张永山 《气象》2016,42(12):1522-1530

国际电工委员会编制的《风力发电机组设计要求》(IEC 61400-1)推荐了针对风电机组安全等级评估的极端风速和湍流强度特征值估算方法,因其简单便捷,在风电领域被广泛采用。利用全国风能资源专业观测网的193座测风塔观测数据,对IEC推荐的极端风速计算方法与我国规范推荐的基于极值I型概率分布方法进行比较,发现两种方法计算的193座塔70 m高度层50年一遇10 min平均最大风速,仅有7座测风塔较为一致,差异在±1%;IEC推荐方法的计算结果多数偏小,其中偏小10%以上的测风塔有121座,偏小30%以上的有44座测风塔,而偏大10%以上的只有9座测风塔;IEC方法计算的极值风速大幅度偏小的测风塔主要分布在台风影响的东南沿海地区,偏差较小的测风塔主要分布在西北和华北地形平缓区域,但同时偏大10%以上的测风塔也多分布在这一地区。以目前行业领域普遍采用的以15 m·s~(-1)风速的平均湍流强度作为风电机组选型指标,与严格按照规范,以15 m·s~(-1)风速段所有样本湍流强度的90%分位数处的值作为指标进行风电机组等级确定作对比,发现193座塔中有46座塔的选型是不安全的,甚至相差两个等级。  相似文献