柴北缘苦水泉金矿英云闪长岩和细粒闪长岩年代学、地球化学和Hf同位素及地质意义

苦水泉金矿床位于柴北缘构造带中段,是近年来新发现的金矿床。该矿床具有造山型金矿的特征,矿体沿断裂构造分布在英云闪长岩中,空间上与细粒闪长岩脉密切相关。本文对苦水泉金矿中的英云闪长岩和细粒闪长岩进行了地球化学、锆石U-Pb定年和Hf同位素研究。全岩地球化学分析显示,英云闪长岩具有富钠贫钾(Na_2O/K_2O=6.24～13.09)、高Sr低Y(Sr/Y=205～335)的埃达克岩的特征,与锡铁山榴辉岩中的埃达克质浅色脉体十分相似;细粒闪长岩富铝、钙、铁,贫镁,富集轻稀土(LREEs)和大离子亲石元素(LILEs),贫高场强元素(HFSEs),Ni、Co含量低,为典型的大陆下地壳来源的岩石。锆石U-Pb定年显示,英云闪长岩和细粒闪长岩分别形成于429.9±2.5Ma和428.0 ± 1.9Ma,Hf同位素分析显示英云闪长岩锆石ε_(Hf)(t)值为+9.8～+11.9,二阶段模式年龄(t_(DM2))为613～747Ma,细粒闪长岩锆石ε_(Hf)(t)值为-31.4～-9.9,二阶段模式年龄(t_(DM2))为1722～2803Ma。综合分析表明柴北缘在早志留世正处于大陆地壳俯冲、折返阶段,苦水泉英云闪长岩为俯冲洋壳变质的榴辉岩在陆壳折返阶段发生部分熔融的产物,细粒闪长岩起源于古老的玄武质下地壳的部分熔融。分布在细粒闪长岩上下盘的矿体品位通常远高于平均品位,说明细粒闪长岩为金矿化提供了热动力和热液,也可能提供了部分成矿物质,使得矿体的品位局部变富,由此近似的将细粒闪长岩的年龄作为苦水泉金矿的成矿时代(～428Ma)。苦水泉金矿成矿时代和构造背景的确定,指示柴北缘在早志留世陆壳折返阶段存在一期金矿化。     

Spatially uniform specific discharge from headwater to river basins on the Chinese Loess Plateau

Hydrogeology Journal - Although there is a general consensus that spatial heterogeneity is ubiquitous in hydrological responses, it is common practice to assume a constant specific discharge among...     

九寨沟“8.8”地震背景下火花海钙华坝体无损探测分析

为研究震后九寨沟钙华景区的溶洞、裂隙、暗流等地质特性,丰富钙华景区岩溶洞穴无损探测技术,探讨了多物探技术在多孔疏松钙华地区作业的可靠性。首次运用地质雷达法及高密度电法相结合的无损探测技术,在九寨沟景区火花海特定区域进行了现场勘查和无损探测试验。结合对比两种无损探测成果与测区内出露地质剖面3组勘探数据,结果发现:高密度电法与地质雷达法相结合,两者能优劣互补,相互佐证,在解决钙华区域浅部溶洞、暗流、裂隙等工作中,对探测目标体具有极高的识别度。两种方法探测数据与震后出露剖面地质特征保持极高的一致性,验证了两种无损检测方法在多孔疏松介质条件下数据的真实可靠性,解决了多物探技术在多孔疏松介质地区施工的疑点和难点,丰富了工程物探领域技术。      

钾镁煌斑岩:优质金刚石主要载体与幔源流体活动标志

钾镁煌斑岩是一类较为特殊的火山成因或浅成的超基性岩,是一种重要的深源岩石,是深源岩浆活动的标志性产物,可作为了解地幔信息的窗口,也作为继金伯利岩之后的另一种金刚石寄主岩被持续关注.全球最优质的金刚石产于钾镁煌斑岩中,主要分布于西澳阿盖尔等地.中国钾镁煌斑岩主要分布于黔湘一带、山西饮牛沟、山东大井头、湖北大洪山和西昆仑克里阳地区,综合分析认为,钾镁煌斑岩主要分布于深大断裂附近,中国钾镁煌斑岩受江南台隆西缘的都匀—贵阳—铜仁—怀化深断裂、常德—安仁深断裂以及郯庐断裂带等深大断裂带控制;贵州镇远马坪、湖南宁乡云影窝、山东平邑大井头等钾镁煌斑岩有原生金刚石产出,钾镁煌斑岩的金刚石成矿潜力仍然有待深入研究,尤以湘黔钾镁煌斑岩带、郯庐断裂带大井头等地可望突破.钾镁煌斑岩的标志性矿物有富钛贫铝金云母、钾碱镁闪石、镁橄榄石、镁铝榴石、铬尖晶石、铬铁矿等.其中S1、S2组贫铝富镁铬铁矿对钾镁煌斑岩中金刚石的形成有指示意义.中国钾镁煌斑岩活动具多期性,其中晚侏罗世—早白垩世(147—100 Ma)时期属于中国含金刚石钾镁煌斑岩和相关的金-稀土等金属矿产的重要成矿时期.     

THE TEMPORAL AND SPATIAL DISTRIBUTION OF SEA SURFACE WIND ALONG THE COAST OF GUANGDONG PROVINCE IN CHINA

Temporal and spatial distribution characteristics of sea surface wind in Guangdong''s coastal areas were analyzed with data from four offshore observational stations between 2012 and 2015. The results are shown as follows: (1) The probability distribution of wind speed was basically consistent with Gaussian distribution characteristics; winds of Beaufort force 6 or higher were observed mainly in far offshore stations from October to March. (2) The probability distribution of wind direction was represented well by Weibull distribution. The deviation of wind direction of far station was relatively small for it was mainly controlled by monsoon over the South China Sea, while the near offshore station had a relatively large diurnal variation because of the influence of local synoptic systems such as sea-land breeze. (3) There were significant seasonal differences in wind speed and direction observed by different offshore observational stations. In strong wind seasons, the deviation of wind direction was relatively small while the deviation of wind speed was relatively large, and vice versa. In contrast with Class I station, the other three stations exhibited approximately normal distribution of wind direction and wind speed deviations. (4) Wind direction diurnal variation was moderate in windy periods, while it was obvious in relatively lower speed conditions. The deviation of wind speed in windy periods was generally greater because it was influenced by mesoscale weather systems for 10-20 h, and the influence was complicated, resulting in greater local differences in wind speed.     

Interannual and Decadal Changes in Tropospheric Ozone in China and the Associated Chemistry–Climate Interactions: A Review

China has been experiencing widespread air pollution due to rapid industrialization and urbanization in recent decades.The two major concerns of ambient air quality in China are particulate matter(PM) and tropospheric ozone(O_3). With the implementation of air pollution prevention and control actions in the last five years, the PM pollution in China has been substantially reduced. In contrast, under the conditions of the urban air pollution complex, the elevated O_3 levels in city clusters of eastern China, especially in warm seasons, have drawn increasing attention. Emissions of air pollutants and their precursors not only contribute to regional air quality, but also alter climate. Climate change in turn can change chemical processes, long-range transport, and local meteorology that influence air pollution. Compared to PM, less is known about O_3 pollution and its climate effects over China. Here, we present a review of the main findings from the literature over the period 2011–18 with regard to the characteristics of O_3 concentrations in China and the mechanisms that drive its interannual to decadal variations, aiming to identify robust conclusions that may guide decision-making for emissions control and to highlight critical knowledge gaps. We also review regional and global modeling studies that have investigated the impacts of tropospheric O_3 on climate, as well as the projections of future tropospheric O_3 owing to climate and/or emission changes.     

鲜水河下游泥石流发育分布特征研究

鲜水河下游流域处于鲜水河断裂带之南西,总体呈南北走向.受地层岩性、地质构造、新构造活动、河谷地貌演化及气候条件等的控制,流域内泥石流较发育,属泥石流中等发育区.泥石流以暴雨沟谷型泥石流为主,可见少量暴雨坡面型泥石流及古冰川泥石流.泥石流多集中发育于岩性相对软弱的板岩、千枚岩及砂岩与板岩互层的相对宽谷段,多为粘性泥石流.泥石流一般具有多期次发育特征,且规模逐次减小.流域内绝大部分泥石流处于停歇或衰退状态,现代活动性不活跃,现代活动泥石流频度低、规模小,且多发育于植被破坏较严重区域.流域内泥石流活动具有退化的特征,对当地人民生命安全及两河口水库的淤积等影响不大.     

断陷盆地缓坡带河流沉积砂体定量表征及控制因素分析:以霸县凹陷文安斜坡东营组三段为例

断陷湖盆缓坡河流成因砂体是重要的油气储集单元.根据岩心观察、钻井岩/电特征并结合地震沉积学方法,分析断陷湖盆缓坡河流沉积体系和砂体时空分布特征,能为油气精细勘探提供可靠的依据.研究表明,霸县凹陷文安斜坡中部东营组三段周期性地发育4条呈NE-SW辫-曲复合型河流沉积,由河道沉积、砂坝沉积和泛滥平原沉积3种亚相以及辫状河道...     

桐梓北部大竹坝井田含煤地层及可采煤层地质特征

大竹坝井田位于呈北东向展布的松坎复式向斜南东翼之次级褶皱-乐坪背斜南东翼,含煤地层为上二叠统龙潭组(P3l),厚45.61~71.53m,平均厚61.10m,含煤层(线)2~6层,全区可采煤层一层(C3),局部可采煤层二层(C2、C4)。C3煤层具有低挥发份、中灰、中高硫、高固定碳、高熔灰分、高热值的特点。可作工业用煤、动力用煤、气化用煤和化工用煤以及民用等。井田以含煤地层相对较薄,可采煤层少,煤层厚度小,含煤率低为其特征。     

南麂列岛大沙岙沙滩贝类的时空分布

南麂列岛作为观光旅游的休闲去处正在日益升温,其中沙滩游玩是最大的活动亮点,大沙岙是南麂列岛最具代表性的沙滩,沙滩内生活着较多贝类,随大量人员的涌入和沿岸环境污染的日趋加重,大沙岙沙滩贝类的栖息地环境受到了较大程度的危害、人为活动正影响着贝类的生长发育。为探明近年来大沙岙贝类种类、数量及群落结构的变化,在南麂列岛国家海洋自然保护区建立初期(1992年)生态调查的基础上,于2003年再次对大沙岙贝类进行了采样分析,结果表明:大沙岙沙滩12种贝类的平均生物量和栖息密度分别为30.16g/m2和20个/m2,北断面开放区贝类的平均生物量和栖息密度(13.98g/m2和11个/m2)明显少于受监控的南断面核心区(46.33g/m2和30个/m2),贝类的平均生物量和栖息密度的垂直分布低潮区(48.43g/m2和31个/m2)高于中潮区(28.03g/m2和20个/m2),贝类的平均栖息密度7月高于3月,北断面贝类的季节变化、多样性和均匀度指数大于南断面。与建区初期同季调查资料比对发现,2003年北断面贝类数量下降幅度(14倍)显著大于南断面贝类下降幅度(1倍)。分析认为,自然环境变化和人为采捕是影响沙滩贝类数量下降的主要外部因子。