FINE SEDIMENT OF THE UPPER MISSISSIPPI AND ILLINOIS RIVERS AND THE DISASTROUS CONSEQUENCES     

TaWei SOONG 《国际泥沙研究》1999,(2)

IINTRODUCTIONLanddevelopmentandlandusepatternsinthewatershedcaninduceincreasedsedimentloadsinriversandstreams.AGREATIllstudy(1982)illustratedthatsedimentyieldsfromagriculturallandcouldbeseveralfoldsmorethanothertypeoflandusesanderosionsources.ThesamestudyalsodemonstratedthatfinesedimentsweretheheaviestportionoftotalsoillossesfromeachtypeoflandusesinthetwelvehydrologicareasitinvestigatedintheUMRS.Thesamecouldbetrueforotheruplandareasalso.Howeverfinesediments,formthewashloadofthestream…  相似文献   

Discovery and exploration of the Gosowong epithermal gold deposit, Halmahera, Indonesia   总被引：1，自引：0，他引：1  

J. C. Carlile  G. R. Davey  I. Kadir  R. P. Langmead  W. J. Rafferty 《Journal of Geochemical Exploration》1998,60(3):207-227

The Gosowong epithermal gold deposit, on the island of Halmahera in eastern Indonesia, is located in an area of primary tropical rain forest with no previous history of gold mining or record of gold mineralisation. The deposit occurs in a newly recognised mineral district which contains a number of epithermal vein systems and at least two centres of low-grade porphyry style Cu–Au mineralisation. Several zones of argillic and advanced argillic alteration have been noted which may be related to additional centres of mineralisation. Gosowong is classified as a low-sulphidation epithermal quartz vein. Bonanza-grade gold–silver mineralisation is developed in shoots over a 400-m strike section of the vein system. Three types of veining are recognized; quartz–adularia veins and breccias; quartz–chlorite–illite veins and breccias; and crystalline or chalcedonic quartz vein stockworks. The area was targetted using a simple geological concept and the deposit was discovered and tested using basic exploration techniques commonly applied in the rugged tropical terrains of Indonesia. Sequential exploration methods comprised reconnaissance drainage sampling of stream sediment, BLEG and float media, ridge and spur soil sampling, prospect scale grid soil sampling, hand trenching and diamond drilling. Lapse time from identification of the initial reconnaissance anomaly to an inferred resource estimate of almost 1 million ounces of gold was less than 3.5 years. This case history illustrates that very detailed exploration is necessary to locate high-grade vein-type gold deposits in a tropical environment, but demonstrates that such resources still remain to be discovered in the relatively under-explored Neogene magmatic arcs of Indonesia.  相似文献   

利用不规则形状载荷模型研究周边矿山开采对营口倾斜观测的影响     

翟丽娜  贾晓东  焦明若  孔祥瑞  王松阳 《地震》2020,40(2):166-176

在对比地表集中荷载模型和二维有限载荷模型的基础上, 结合营口台SQ-70模拟水平摆倾斜仪2009~2016年异常变化时段受矿山开采影响的实例, 采用二维有限不规则荷载模型定量计算了矿山开采的不同阶段对石英摆倾斜量的影响程度。 结果表明: 营口倾斜观测受周边矿山开采影响严重; 2009年以后矿山开采量引起营口地区地表倾斜的理论值与实际观测值基本相符, 该时段数据破年变异常为矿山开采影响的可能性较大; 2013年以后营口石英摆观测值与矿山开采引起地表倾斜的理论值相差较大, 因此2013年后的数据异常变化不完全是矿山开采引起, 可能是地壳倾斜变化的实际反映。  相似文献   

数字重力仪高精度恒温测温系统设计与测试研究          下载免费PDF全文

秦佩  梁连仲  陶照明  黄涛  刘雨 《地球物理学报》2019,62(10):3665-3674

高精度数字重力仪广泛应用于矿产资源勘探领域,由石英弹性系统组成的重力传感器是高精度数字重力仪的核心部件,其对外界环境温度非常敏感,由环境温度变化引起的重力输出变化远远大于仪器本身精度指标,而且不同的数字重力仪具有不同的温度影响特性.若重力传感器的恒温环境得不到保障,或环境温度的微弱变化无法得到准确的测量和补偿,将严重影响重力仪器的测量精度和一致性.本文针对该问题,研究了高精度恒温测温系统的设计方法及关键技术,考虑到数字重力仪器精度高、体积小、功耗低和便携式的特点,对高精度恒温测温系统中的关键器件选型、热结构设计、电路设计、软件设计等进行深入研究,并给出具体的解决措施.并设计了静态试验、高低温试验和石英弹性系统温度系数测定试验三个部分验证高精度恒温测温系统的有效性.试验结果表明：高精度测温系统最小分辨率达到10 μ℃;静态常温时,高精度恒温系统温度变化约为70 μ℃;在-20℃~+45℃的环境温度冲击中高精度恒温系统温度变化小于1 m℃;恒温点微调装置可实现石英弹性系统温度系数的精确测定.该研究为高精度重力测量仪器研制中消除环境温度变化影响提供了一种有效解决方案.  相似文献   

Luminescence dating of glaciolacustrine silt in overdeepened basin fills beyond the last interglacial     

《Quaternary Geochronology》2017

OSL and IRSL dating are applied to samples from a 152 m-long drill core to constrain the timing of three glaciolacustrine depositional periods within the infill of an overdeepened bedrock trough in the Lower Glatt valley, N Switzerland. The characterisation of the dose-response suggests that the polymineral IRSL₅₀ and pIRIR_180/225 signals are close to saturation, while quartz OSL ages are within the range of reliable dating. The demarcation of the upper quartz OSL dating limit, however, remains challenging. Dose-recovery tests performed with long storage periods were used to investigate the reliability of the high region of the dose-response curve. They suggest an upper limit for reliable dating of ∼400 Gy for these samples, which was considerably lower than the commonly used 2D₀ criterion. Lifetimes were calculated for the quartz OSL and the thermal stability of the signal is not considered as problematic for the determined ages. Allowing for a contribution from inherited dose due to partial bleaching, places the infill of the overdeepened valley within the penultimate glacial cycle (MIS6).  相似文献   

三维激光扫描技术在青岛市房地产开发中的应用     

白立飞  于广婷  卢晓龙  韩金芳 《山东国土资源》2011,27(3):41-43

三维激光扫描技术是一种先进的全自动高精度立体扫描技术,又称为"实景复制技术",是继GPS空间定位技术后的又一项测绘技术革新,使测绘数据的获取方法、服务能力与水平、数据处理方法等进入新的发展阶段。该文结合工程实例,对该项技术用于三维精准地形测绘的方法进行了实践与研究,并对该技术存在的一些问题做了一些探讨。  相似文献   

The SPICE project: Calibrated cosmogenic 26Al production rates and cross-calibrated 26Al /10Be, 26Al/14C,and 26Al/21Ne ratios in quartz from the SP basalt flow,AZ, USA     

《Quaternary Geochronology》2022

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