PRELIMINARY STUDY ON THE OPHIOLITIC MELANGE IN THE YALU TSANGPU GRAND CANYON AREA

PRELIMINARY STUDY ON THE OPHIOLITIC MELANGE IN THE YALU TSANGPU GRAND CANYON AREA     

The future of chemical in situ sensors

Many of the sampling methods used in oceanographic sciences today date back decades, if not centuries. Although there has been a marked change in how sampling for chemical oceanography is carried out it still relies on taking samples of seawater from a research vessel in most cases. Assessing processes on small timescales as well as transient events requires higher temporal and spatial resolution of measurements; long time series stations require high duration deployments of instruments. Both requirements can only be adequately satisfied by in situ sensors; for the physical parameters off the shelf instruments are available, in the field of chemical oceanography only a few parameters, such as oxygen, are covered by off the shelf instruments, for most parameters adequate instrumentation only exists in the form of prototypes, if at all. Chemical in situ sensors are needed to gain new insights in how the oceans and the life in it works.     

地下水中半挥发性有机污染物痕量分析的5个问题探讨

针对地下水中有机氯农药、多氯联苯和多环芳烃等半挥发性有机污染物的痕量分析,从实验室分析测试人员的角度,探讨了提高定量分析准确度的三个问题:分级绘制标准曲线、注重标准溶液配制细节、避免假阳性与假阴性.从实验室管理人员的角度探讨了提高实验室竞争力的两个问题:提高服务质量和降低分析成本.本文对这几个重要但往往易被忽视的问题进行逐一分析,并探讨了分级绘制标准曲线的方法、配制标准溶液应考虑的要点、避免假阳性与假阴性的措施,以及提高服务质量和降低成本的因素.     

基于GIS冰川末端变化计算方法研究——以北极Austre Lovénbreen冰川为例

基于冰川区地形图和实地GPS测量数据,总结4种用于计算冰川末端变化量的方法:主流线法、中心线法、周长法和特征点法,并提出基于GIS的操作思路.分析了各种方法的优缺点,阐述了各种方法在使用中的注意事项.建议使用最短距离的特征点法计算冰川末端变化量,并且以前一期的特征点向后一期的冰川边界搜索最短距离.通过把方法应用在北极Austre Lovénbreen冰川,结果表明,自2005年观测以来北极Austre Lovénbreen冰川末端呈现退缩趋势,年均退缩量为9.44m.a-1,年际变差系数为0.40,冰川末端变化量年际变化较大.     

岩土工程勘察中的质量控制探讨

本文阐述了岩土工程勘察成果质量的重要性,重点论述了岩土工程勘察工序流程的质量管理要点,这对于岩土工程勘察专业宏观管理到指导具有实际意义。     

长白山北坡岳桦林线变动的水热条件分析

近50年来长白山北坡林线种群呈现明显的扩张态势。为揭示林线变动机制,本文以长白山天池气象站的气象数据(1953-2007年)为基础,结合野外的气温观测,以温暖指数(WI)及湿润指数(HI)为生态气候指标,以16℃·月和68.8 mm/℃·月为阈值,通过数据保证率的计算推测55年来长白山北坡岳桦林线的水热条件变化。结果表明:以WI和HI指标确定的林线位置分别在1975~2460 m和1584~2231 m。WI与HI变化对林线高度变动影响的交互作用不显著(p>0.05),WI与HI变化呈显著负相关(p<0.01),两种林线变化也呈负相关(r=-0.11<0),交互作用和相关分析结果显示水热条件的不同步变化使岳桦林线上侵不能达到各自的潜在高度,林线位置波动在1975~2231 m。林线上缘波动的复杂程度高于下缘,波动幅度与胁迫力的大小呈正相关。     

Physical Modeling of Fold-and-Thrust Belt Evolution and Triangle Zone Development:Dabashan Foreland Belt(Northeast Sichuan basin,China) as an Example

Triangle zones,generally found in foreland fold-and-thrust belts,serve as favorable objects of petroleum exploration.Taking the Dabashan foreland belt as an example,we studied the formation and development of triangle zones,and investigated the effect of decollements and the mechanical contrast of lithology by employing the method of physical modeling.Four experimental models were conducted in the work.The results showed that ’sand wedges’ grew episodically,recorded by deformational length,height and slope angle.The height versus shortening rate presented an S-shape curve,and uplifting occurred successively in the direction of the foreland belt.During the formation of the triangle zone,layer-parallel shortening took place at the outset;deformation decoupling then occurred between the upper and lower brittle layers,divided by a middle-embedded silicone polymers layer.The upper brittle layers deformed mainly by folding,while the lower sand layers by thrusting. As shortening continued,the geometry of a triangle zone was altered.We consider that the triangle zone in the Dabashan foreland belt was modified from an early one based on available seismic profiles and the experimental results.In addition,decollements and mechanical contrast impose significant influence on structural development,which can directly give rise to structural discrepancies.More decollements and obvious mechanical contrast between brittle layers can promote the coupling between the upper and lower brittle layers.Basal decollement controls the whole deformation and decreases the slope angle of the wedge,while roof decollement determines whether a triangle zone can be formed.     

新疆吐尔库班套蛇绿混杂岩的发现及其地质意义

蛇绿岩作为残留洋壳的良好记录,对于研究古板块构造及其演化具有重要意义。新发现的吐尔库班套蛇绿混杂岩位于新疆阿尔泰布尔津南部,主要由超镁铁岩、辉长岩、辉绿岩、玄武岩、复理石建造等构成。其中辉长岩和片麻状花岗岩的锆石U Pb年龄在363～355 Ma,指示蛇绿岩的形成、洋壳俯冲时代在晚泥盆世晚期。岩石地球化学特征表明,该蛇绿岩套的镁铁超镁铁岩和玄武岩属低碱、低钛、富镁的拉斑玄武岩系列,具有较典型的幔源岩石特征,玄武岩形成于类似洋中脊的构造环境。混杂岩带中的片麻状花岗岩属于钠质的低钾岩石系列,形成于火山弧或同碰撞构造环境,亦为洋壳俯冲的结果。吐尔库班套蛇绿岩与科克森套、乔夏哈拉、布尔根蛇绿岩一起构成了沿额尔齐斯分布的蛇绿混杂岩带,构成了分割西伯利亚板块和哈萨克斯坦-准噶尔板块的斋桑-科克森套-南蒙古缝合带。     

A workflow for exploration sampling in regolith-dominated terranes using portable X-ray fluorescence: comparison with laboratory data and a case study

This paper presents and validates a workflow that provides for the rapid collection of reliable and robust portable X-ray fluorescence (pXRF) data in a regolith-dominated exploration setting. The analysis of regolith material by pXRF is challenging because of its variable Fe content (e.g. 0 to >70 wt%) that results in large matrix effects, which can be mitigated with appropriate standards. Here, we present a dataset from the Western Mount Isa Inlier, Queensland, Australia, comprising soil, lag, rock and rotary air blast (RAB) samples. In the soil dataset, comparison of the laboratory and pXRF datasets for Cu, Pb and Zn have R² > 0.9, and Cu and Zn fall within 2% of the laboratory data, while Pb is 77% less than the corresponding laboratory analyses. Iron, Al, K and Ca by pXRF perform reasonably well when compared with the laboratory data (R² = 0.59 for Al, R² > 0.9 for Fe, K and Ca, <25% variation from the laboratory data), while Mn, Rb and Sr have very good correlations (<8% variation) with R² > 0.94. Titanium, Zr, Ni, Cr and As have poorer comparisons. Overall, the RAB dataset shows similar trends with Cu overestimated by 17%, Zn underestimated by 4% and Pb overestimated by 69%; R² for all elements is >0.92. Since no suitable standards are available, the solid rock dataset was uncorrected; despite this limitation, the dataset shows good correlations with the laboratory data for many elements, and Cu is overestimated by 9.8% with an R² = 0.87. The poor analytical performance of Pb in all datasets is associated with erroneous Bi concentrations being reported by the pXRF unit. When high Fe and Pb amounts are present in a sample, erroneous Pb and Bi concentrations are reported, owing to a pile-up of the Fe K_α peak (6.405 keV) at ～12.8 keV, which is proximal to the Pb L_β (12.614 keV) and Bi L_β (13.023 keV) peaks. Despite the care that is required in validating data, by using pXRF there is substantial opportunity for dynamic exploration campaigns in regolith-dominated terranes with rapid turnaround times, additional elements that may not otherwise be analysed for and low analytical costs. Decisions to stop, continue or infill drill holes while the drill rig is present can be made in near-real time, and not after laboratory results are available and the drill rig has left the area.     

青海省玛沁县友后青地区钴铜矿化带成矿地质特征及找矿前景

青海玛沁县友后青地区大地构造位置处于阿尼玛卿缝合带内,在友后清地区发现了与基性-超基性岩体关系密切的钴铜矿化带。本文主要分析了友后青地区钴铜矿化带的成矿地质特征,认为华力西-印支期NW-NWW向的深大断裂控制着钴铜成矿作用。高精度磁测显示,区内有一条近NWW走向的磁异常带,异常强度中等偏高,呈串珠状分布。水系沉积物测量表明,以镍钴铬为主的多金属综合异常规模大,元素组合齐全,镍钴铬元素异常套合好。水系沉积物地球化学异常与高精度磁测异常可以很好的叠合在一起,在空间上与基性-超基性岩关系密切。沿NW-NWW向断裂带,与基性-超基性岩叠合较好的物化探异常区是该地区寻找钴铜矿的有利地段。