内蒙古得尔布干森林沼泽区遥感地质解译研究

利用遥感技术在内蒙古得尔布干森林沼泽区开展地质解译研究。试图通过选择适合该区特点的遥感图像，在宏观地质解译基础上对区域构造展布特征有其控矿规律进行重点研究，进而预测贵重金属（Au、Ag）及有色金属（Cu、Pb、Zn）成矿带，为区内新一轮国土资源大调查提供一些有参考价值的遥感地质信息。     

Kuskonook Creek, an example of a debris flow analysis

Two debris flows occurred on Kuskonook Creek in British Columbia, Canada, in August and September 2004. The initiation factors included a major forest fire in the catchment in 2003, in association with relatively small rainfall events and the accumulation of sediment in the creek channels since the last large debris flow event. Previous regional studies and morphometric comparisons with other similar catchments indicate that Kuskonook Creek has characteristics predisposed to debris flows, even without the affects of a forest fire. Based on the investigations and analyses, a magnitude/frequency relationship for future debris events on Kuskonook Creek was developed, and this information was used to carry out a partial risk assessment. It is suggested that for design purposes, a 1/50-year return period and the corresponding debris flow magnitude of 15,000 m³ would provide conservative protection to the users of the provincial highway at the mouth of the creek.     

Flume experiments on the horizontal stream offset by strike‐slip faults

Flume experiments, in which the middle section of an erosion channel is displaced horizontally, have been conducted to assess the response of streams to horizontal displacement by a strike‐slip fault. The experimental erosion channel was developed in a mixture of sand and clay, which provided relatively stable banks with its cohesiveness. Horizontal displacement of a strike‐slip fault perpendicular to the channel is expected to add a ?at section to its longitudinal pro?le along the fault line. The experimental stream eliminated this ?at section with downstream degradation, upstream aggradation, and lateral channel shift. As a result, a roughly continuous longitudinal pro?le was maintained. This maintenance of a continuous longitudinal pro?le along channel is considered to be the principle of stream response to horizontal displacement by a strike‐slip fault. Downstream degradation was the dominant process of this stream response in the overall tendency of erosion without sand supply. When the rate of fault displacement was low (long recurrence interval), the experimental stream eroded the fault surface, jutting laterally into the channel like a scarp, and de?ected the channel within the recurrence interval. This lateral channel shift gave some gradient to the reach created by fault displacement (offset reach), and the downstream degradation occurred as much as completing the remaining longitudinal pro?le adjustment. When the rate of fault displacement was high (short recurrence interval), the lateral erosion on the ?rst fault surface was interrupted by the next fault displacement. The displacement was then added incrementally to the existing channel offset making channel shift by lateral erosion increasingly dif?cult. The channel offset with sharp bends persisted without much modi?cation, and downstream degradation and upstream aggradation became evident with the effect of the offset channel course, which worked like a dam. In this case, a slight local convexity, which was incidentally formed by downstream degradation and upstream aggradation, tended to remain in the roughly continuous longitudinal pro?le, as long as the horizontal channel offset persisted. In either case, once the experimental stream obtained a roughly continuous gradient, further channel adjustment seemed to halt. Horizontal channel offset remained to a greater or lesser extent at the end of each run long after the last fault displacement. Copyright © 2004 John Wiley & Sons, Ltd.     

Geomorphic controls on contaminant distribution along an ephemeral stream

Sediment‐borne contamination in a watershed can be highly variable as a result of ?uvial processes operating over a range of time scales. This study presents a detailed analysis of the distribution of one contaminant along an ephemeral stream after 55 years of sediment transport, deposition, and exchange by ?ash ?oods. Wastewater containing plutonium was discharged into the Pueblo Canyon watershed from 1945 until 1964, and plutonium concentrations in ?uvial deposits vary over ?ve orders of magnitude. These variations can be attributed to three primary factors: time since contaminant releases, particle‐size sorting, and mixing of sediment from different sources. The highest concentrations occur in ?ne‐grained sediment deposits near the source that date to the period of ef?uent releases, and concentrations are lower in younger deposits, in coarser‐grained deposits, and in deposits farther downstream. The spatial distribution of plutonium is strongly affected by longitudinal variations in the size of sediment deposits of different age. A major aggradation–degradation cycle in the lower canyon overlapped with the period of active ef?uent releases, and a signi?cant portion of the total plutonium inventory is contained within large coarse‐grained deposits below ?ll terraces that post‐date 1945. The spatial pattern of contamination is thus determined by the speci?c geomorphic history of the watershed, in addition to processes of mixing and sorting during transport that occur in all ?uvial systems. Copyright © 2004 John Wiley & Sons, Ltd.     

河南省下蒿坪金矿区分散流异常特征及找矿效果

通过1∶5万分散流测量,在河南省店房-下蒿坪地区发现一处分布面积很大的Au、Pb、Ag、Hg、Zn、Bi、W等元素的组合异常。经对异常的地质查证、山地工程验证,发现一可供进一步详查的中型金矿床,金矿化类型为硅化石英脉型和蚀变破碎带型,金最高品位为14.30×10-6,预测金资源量(333)+(3341)大于10t,取得了明显的找矿效果。     

新疆西昆仑库斯拉甫铅锌铜成矿带水系沉积物测量及其找矿效果

文章介绍了新疆西昆仑中高山区水系物测量的方法技术,并总结了异常浓集区和矿集区的展布规律.通过对异常区找矿成果的介绍,重点剖析了该区两类重要矿床——碳酸盐岩型铅锌矿床和砂（砾）岩型铅铜矿床的地球化学异常规模、形态、展布、组合特征,及其找矿效果.     

岩石节理对大石林景观空间结构塑造和控制

大石林景区节理走向集中在NW30°～60°以及NE50°～75°两个方向,形成“X”型共扼性质,表现出高密度、高角度、深切割、延伸长的特点。景区剑状石林与溶蚀洼地的组合、石柱的定向展布以及空旷地、廊道和游路所体现出的特有空间结构都受到上述节理的塑造和控制。     

辫状沉积砂体与砂岩型铀矿的关系剖析

砂岩型铀矿是后生的铀矿类型之一, 其成矿受盆地盖层结构和砂体的发育状况、以及盆地形成后由构造翻转形成的渗入型水动力系统的双重控制。这两者耦合的优劣, 完全取决于砂体的沉积特征。本文运用沉积体系理论分析了两类不同的沉积砂体, 得出辫状沉积砂体对铀成矿最为有利的认识。该类砂体可产于冲积扇、河流和辫状三角洲等沉积体系中。     

基于地球化学块体概念的中国锡资源潜力评价

本文详细介绍了根据地球化学块体的概念、利用中国区域化探扫面的成果对中国锡资源潜力评价的方法技术；给出了金属供应量、地球化学块体成矿率、资源量和潜在资源量的计算公式，并引入了校正系数来修正根据水系沉积物计算的地球化学块体中的金属供应量；描述了中国锡地球化学块体的空间分布特征，分析了这些地球化学块体与地质体和已知锡矿床的空间对应关系；确定了中国锡在8ug／g、10ug／g含量级次的地球化学块体成矿率为0．205％和0.208％。同时根据在中国大陆所圈定的锡地球化学块体的分布及其特征计算出中国锡的潜在资源量为1609万t和1406万t。