昌宁-孟连结合带牛井山早古生代埃达克岩锆石U-Pb年龄、岩石成因及其地质意义

昌宁-孟连结合带是西南三江地区重要的古特提斯结合带,本文报道该带牛井山蛇绿混杂岩带内的早古生代英云闪长岩的锆石U-Pb年龄和Hf同位素、全岩地球化学特征,探讨其岩石成因,揭示早古生代(原)特提斯演化过程和恢复古地理格局。利用LA-ICP-MS对英云闪长岩进行锆石U-Pb定年,获得~(206)Pb/~(238)U加权平均年龄为468±2Ma(MSWD=1.4,n=22),代表岩浆岩结晶时代。对锆石进行原位微区Hf同位素分析获得锆石ε_(Hf)(t)=+1.6~+2.8。牛井山英云闪长岩具有高的SiO_2(61.6%~67.16%),Al_2O_3(15.4%~17.64%),Na_2O(2.93%~3.25%)含量,高的Na_2O/K_2O(3.9~5.4)比值。微量元素具有高Sr(469×10~(-6)~533×10~(-6)),低Yb(0.66×10~(-6)~1.22×10~(-6))和Y(8.5×10~(-6)~16.3×10~(-6)),Eu正异常(1.01~1.37)的特征。此外,在同等SiO 2条件下,还具有相对高的Mg~#和MgO(Mg~#=50~51,MgO=2.84%~3.58%)。这些特征表明英云闪长岩具有高镁埃达克岩的性质。岩石成因研究表明牛井山高镁埃达克岩很可能是俯冲洋壳加上部分大洋沉积物部分熔融并与上覆地幔橄榄岩反应的产物。早古生代洋壳俯冲成因的埃达克岩的发现证明昌宁-孟连特提斯洋演化历史可追溯至约468Ma。昌宁-孟连结合带早古生代岩浆作用与龙木错-双湖结合带早古生代洋壳残片的时代一致、构造属性相似,我们认为昌宁-孟连结合带与木错-双湖结合带可对比,它们代表了一个统一的古生代特提斯大洋残余。     

新疆白杨河铍铀矿床萤石Sm-Nd和沥青铀矿U-Pb年代学及其地质意义

白杨河矿床是我国类型独特的一个特大型铍、铀多金属矿床,铍矿物主要确定为羟硅铍石,铀矿物主要发现沥青铀矿和次生的硅钙铀矿以及少量的铌铀矿,伴生矿物主要是萤石。为恢复铀和铍的成矿过程,划分成矿阶段,本次工作通过系统采集钻孔中的萤石样品,进行了Sm-Nd同位素测年研究,获得了三组等时线年龄,分别为291±16Ma、265±33Ma和207±37Ma,代表了成矿前、成矿期和成矿后萤石的形成;采集中心工地、新西工地和九号工地平巷内的沥青铀矿样品,进行了UPb同位素测年研究,获得了~(206)Pb/~(238)U表观年龄237.8±3.3Ma、224±3.1Ma、197.8±2.8Ma、97.8±1.4Ma和30.0±0.4Ma,利用U-Pb表观年龄将铀矿化划分为四个阶段:中三叠世、晚三叠-早侏罗世、晚白垩世和古近纪中期。因此,白杨河矿床具有铍早铀晚的成矿特点,铀成矿经历了四个阶段。     

延边和龙地区地质特征及地基承载力的研究

关于延边和龙地区地质特征及地基承载力确定方法的研究较少,通过土工试验,重型动力触探试验和标准贯入试验原位测试方法,分别对和龙地区常在工程中用作持力层的圆砾层和全风化泥岩层的地基承载力进行了测试研究,得到了圆砾层颗粒级配、地基承载力特征值、变形模量的数据,全风化泥岩层地基承载力特征值的数据。对试验数据进行统计分析,得出和龙地区圆砾层地基承载力范围,得出圆砾层地基承载力特征值、变形模量与重型圆锥动力触探锤击数线性相关的结论,以此建立适合当地地质条件的相关经验公式。为延边和龙地区岩土工程勘察工作确保获得可靠、适用的岩土参数提供经验与依据,为周边相似地层的研究提供参考。     

青海德令哈盆地石炭纪古环境研究

采自德令哈地区石炭系的12个碳酸盐岩样品测试、分析结果表明,德令哈地区石炭纪整体为分层中等的弱还原海相环境,水体受陆源碎屑注入影响明显。这种湿热、还原的高盐度水体利于生物的繁盛及有机质的保存,使德令哈地区石炭系发育极为优越的烃源岩条件。垂向上,克鲁克组偏高的咸化程度及分层程度,表明克鲁克组沉积水体相对闭塞、咸化程度较高,而怀头他拉组、扎布萨尕秀组灰岩形成于水体交换相对通畅的海域。从岩性组合、陆源碎屑注入变化及盐度、还原性的差异来看,克鲁克组主体为局限台地环境,而怀头他拉组、扎布萨尕秀组为开阔台地。作为对克鲁克组高盐度、还原性水介质环境的响应,克鲁克组烃源岩TOC条件要比怀头他拉组及扎布萨尕秀组优越。     

Regional debris flow susceptibility analysis based on principal component analysis and self-organizing map: a case study in Southwest China

A method was developed to analyze the susceptibilities of 541 regional basins affected by debris flows at the Wudongde Dam site in southwest China. Determining susceptibility requires information on source material quantity and occurrence frequency. However, the large number of debris flows can hinder the individual field investigation in a each small basin. Factors that may trigger debris flows can be identified using remotely sensed interpretation information. Susceptibility analysis can then be conducted based on these factors. In this study, SPOT5 satellite imagery, digital elevation models (DEM), a lithology distribution map, and rainfall monitoring data were used to identify 12 debris flow trigger factors: basin relief ratio, slope gradient in the initiation zone, drainage density, downslope curvature of the main channel, vegetation coverage, main channel aspect, topographic wetness index, Melton’s ruggedness number, lithology, annual rainfall, form factor, and cross-slope curvature of the transportation zone. Principal component analysis was used to obtain the eight principal components of these factors that contribute to susceptibility results. Then, a self-organizing map method was adopted to analyze the principal components, which resulted in a debris flow susceptibility classification. Field validation of 26 debris flow basins was used to evaluate the errors of the susceptibility classification, as well as assess the causes of such errors. The study found that principle component analysis and self-organizing map methodologies are good predictors of basin susceptibility to debris flows.     

象山港海洋牧场示范区大型底栖生物的时空变化

根据象山港海洋牧场示范区建设前(2011年)、建设中(2012年)、建设后(2013年)对象山港全港区、邻近区、示范区11个站位,进行5个航次调查所获得的大型底栖生物的资料,对比分析建设前后大型底栖生物的时空变化。结果表明:共鉴定出大型底栖生物59种,建设后建设中建设前,优势种变化明显。大型底栖生物密度、生物量表现为:建设前建设中建设后;建设中建设后建设前。多样性指数H’、丰富度指数d均表现为:建设前建设后建设中,均匀度指数J则表现为建设中建设后建设前。多因子方差分析结果表明:建设前后,大型底栖生物种类数、栖息密度、生物多样性指数均存在显著性差异。根据群落聚类及n MDS排序分析,建设前后大型底栖生物群落组成存在明显差异,双因素相似性分析(ANOSIM)结果同时表明,群落建设前后存在显著性差异(综合检验R=0.215,P=0.004)。SIMPER分析,大型底栖生物群落的平均相似性建设前建设后建设中。根据调查站位的数据作出丰度/生物量比较曲线(ABC曲线)分析表明,建设中大型底栖生物受到了强烈的干扰,人工鱼礁投放、大型海藻移植、增殖放流会对其周围海域产生影响,但建设后扰动消失,表明随着时间的推移,海洋牧场建设过程中带来的扰动逐渐减小,并围绕鱼礁群逐渐形成新的人工生态系统。     

东海内陆架沉积物敏感粒级构成及其地质意义

沉积物粒级包含了大量的沉积环境信息,在古环境恢复和重建中被广泛应用。基于采自东海内陆架的三根沉积物岩芯,作者利用激光粒度分析方法研究了沉积物的粒度组成,确定了敏感性粒级,探讨了搬运机制及其环境意义。研究表明:东海内陆架现代沉积物含有大致相同的三个敏感性粒级,分别是粒级1(12μm)、粒级2(12—225μm)和粒级3(225μm)。从北到南敏感粒级具有逐渐细化的趋势,该趋势与长江入海沉积物向南搬运过程中发生的沉积分异作用有关。粒级1和粒级2分别由均匀悬浮次总体和递变悬浮次总体构成,而粒级3则由生物过程产生。结合该区的海洋动力特征,作者认为,粒级2可较好地用来指示冬季海洋动力强度,并具有揭示东亚冬季风强度的潜在意义。     

胶州湾沉积物重金属形态不同浸取方法的比较与污染讯息指示作用初探

海洋沉积物中重金属的活性形态对于指示沉积物污染状况具有重要作用;为探寻简洁且能够有效提取重金属活性形态的浸提方法;实验研究了0.1 mol/L和1 mol/L盐酸的单级提取和欧共体标准局（European Community Bureau of Reference）提出的BCR分级提取法对胶州湾表层沉积物中重金属（Cr、Cu、Ni、Pb、Zn）和Al、Fe、Mn的浸取效果。结果显示;3种提取方法提取的金属含量呈显著正相关关系;两种浓度的稀盐酸对BCR方法中的酸可提取态和可还原态金属均具有较好浸提效果;但对可氧化态金属浸提能力相对较弱。不同提取方法的人为信号指数（ASI）计算结果表明;BCR浸取法提取结果的金属ASI值最大;表明其对沉积物中金属活性形态提取效率较高;1 mol/L HCl提取结果的金属ASI值最低;可能是较高浓度强酸使沉积物较大颗粒内层中“惰性”金属被浸取出来;“增加”了金属活性组分的污染讯息信号;对沉积物中Cu、Pb和Zn而言;0.1 mol/L HCl提取结果的ASI值与BCR方法接近。经过Al归一化后;0.1 mol/L HCl浸提的重金属含量的空间分布与胶州湾的实际污染状况相吻合;表明0.1 mol/L的HCl在一定程度上能够代替复杂的BCR浸取法;此方法可简化重金属活性形态的提取步骤;适合大范围沉积物重金属污染评价。     

北大西洋大青鲨渔业生物学初步研究

大青鲨(Prionace glauca)是金枪鱼延绳钓渔业中最主要的兼捕鱼种之一,作为海洋生物链的顶端物种对海洋生态系统的稳定性和多样性起到了重要作用。作者根据中国金枪鱼渔业科学观察员在北大西洋海域(3°~55°N,15°~40°W)采集的2 112尾大青鲨数据,按不同性别对其渔业生物学特征进行初步研究。结果表明:雌、雄大青鲨的优势叉长组分别为180~220 cm、190~230 cm,雄性叉长均值显著大于雌性,雌、雄性比符合1︰1;大青鲨叉长-全长、尾凹长-全长的线性关系分别为L_F=0.8008L_T+7.3361,L_P=0.7576L_T–1.8479;北大西洋热带海域(3°~13°N)兼捕的大青鲨群体组成以大个体为主(180~240 cm),冰岛附近海域(48°~51°N)兼捕的大青鲨群体组成以小个体为主(100~210 cm);大青鲨叉长和质量关系式为W_R=7×10~(–6)L_F~(2.9994);大青鲨肝脏为性腺的发育提供能量,成熟个体的肝质量指数显著小于未成熟个体;热带海域兼捕的大青鲨以性成熟个体为主(96.9%),冰岛海域兼捕的大青鲨以未成熟个体居多(77.1%);50%雌性性成熟个体对应的叉长为178.7 cm,50%雄性性成熟个体对应叉长为173.6 cm;雌性怀仔大青鲨的叉长与其怀仔数量线性关系为L_S=0.419×L_F–49.7(R~2=0.3905),幼仔雌雄性比符合1︰1;胃含物中以沙丁鱼和鱿鱼出现频率最高。作者的研究有助于更好地了解北大西洋大青鲨的生物学特征,为区域性渔业管理组织评估大青鲨种群资源状态提供数据参考。     

The Air-Coastal Sea Chemical Exchange: A Case Study on the New Jersey Coast

The coastal marine atmosphere adjacent to large urban and industrial centers is in general strongly impacted by pollution emissions, resulting in high loading of pollutants in the ambient air. Among the airborne substances are certain trace elements from a variety of emission sources that can serve as micronutrients to marine organisms in coastal waters. High concentrations of such elements in coastal air can result in enhanced air-to-sea deposition fluxes to coastal waters. They could also be transported over the open ocean, affecting the composition of the remote marine atmosphere and then ocean ecosystems. To provide better understanding of the extent of air-to-sea deposition processes on the New Jersey coast, a heavily polluted coastal region on the US East Coast, a synthesis of observation data was carried out for selected trace elements, including Fe, Cd, Cr and Cu, derived from measurements of both size-segregated and bulk aerosol particles, as well as precipitation around the New Jersey coast. The atmospheric input of Hg was also estimated based on measurement data. Results indicated that the total deposition fluxes of most trace elements were higher in Northern coastal NJ compared to Southern coastal NJ, reflecting the differences in the source strengths of these element emissions between the two coastal regions. Dry deposition processes were more significant for common dust-derived elements, particularly Fe and Al, compared with their wet deposition fluxes. However, the processes of precipitation scavenging appeared to be more important for the elements that were often enriched in fine particles including Zn, Cu, Pb and Ni. The removal of Hg from the ambient air was overwhelmingly dominated by atmospheric wet deposition. In the future, atmospheric measurements at more sites on the NJ coast should be performed simultaneously to reduce the spatial and temporal uncertainties associated with atmospheric deposition fluxes estimated in this study.