斑岩型铜矿找矿预测中环形构造的示矿作用——以玉龙—马拉松多子区为研究区   总被引：2，自引：0，他引：2  

张廷斌  别小娟  吴华  胡紫豪  李建力  杨雪 《国土资源遥感》2012,(1):143-149

在斑岩型铜矿资源潜力评价中,斑岩体是圈定铜矿最小找矿预测区的重要依据。研究表明,遥感图像上的许多环形影像与岩浆活动(包括斑岩体)有关。为了快速进行斑岩型铜矿成矿预测,利用遥感技术在西藏玉龙—马拉松多斑岩型铜矿周边地区开展了找矿预测。首先建立了环形构造的遥感解译标志;然后开展了环形构造的解译工作,研究了该区环形构造的展布特征;最后总结了由环形构造推断斑岩体的标志。结果表明,遥感解译的环形构造为该区斑岩型铜矿最小找矿预测区的圈定提供了重要依据。  相似文献   

The Role of Land-sea Distribution and Orography in the Asian Monsoon. Part II： Orography     

XU Zhongfeng  QIAN Yongfu  FU Congbin 《大气科学进展》2010,27(3):528-542

The role of various mountains in the Asian monsoon system is investigated by AGCM simulations with different mountains. The comparison of the simulation with Asian mountains (MAsia run) with the simulation without mountains (NM run) reveals that the presence of the Asian mountains results in a stronger South Asian summer monsoon (SASM), characterized by enhanced lower-tropospheric westerly winds, upper-tropospheric easterly winds, and stronger water vapor convergence. In East Asia, the southerly winds and water vapor convergence are significantly strengthened in association with the intensified zonal pressure gradient between the East Asian continent and the Pacific Ocean. Both the dynamical and thermodynamic forcing of the Tibetan Plateau play important role in strengthening the Asian summer monsoon. In winter, the presence of Asian mountains significantly strengthens the continental high, which leads to a stronger Asian winter monsoon. The presence of African--Arabian mountains helps to intensify the exchange of mass between the Southern Hemisphere and Northern Hemisphere by strengthening the cross equatorial flows in the lower and upper troposphere over East Africa. Asian mountains also play a crucial role in the seasonal evolution of Asian monsoons. In comparison with the NM run, the earlier onset and later withdrawal of lower-tropospheric westerly winds can be found over South Asia in the MAsia run, indicating a longer SASM period. The African--Arabian mountains also moderately contribute to the seasonal variation of the South Asian monsoon. In East Asia, the clear south-to-north march of the southerly winds and subtropical rainfall starts to occur in early summer when the effects of Asian mountains are considered.  相似文献   

晚更新世时期燕山山区的环境演变     

许清海  阳小兰  柯竹梅  梁文栋  杨振京 《地理与地理信息科学》2002,18(2):69-72

晚更新世时期 ,燕山西部山区是一种激烈动荡的地貌水文条件 ,东部山区较稳定 ,发育了河湖相沉积。孢粉分析和哺乳动物化石都表明当时是一种以草原为主的森林草原或苔原景观。其中 ,2 10 0 0aBP .之前的古气候为寒冷稍湿时期 ,2 10 0 0～ 170 0 0aBP .为极度寒冷时期 ,170 0 0～ 12 0 0 0aBP .为气温回升时期 ,12 0 0 0～ 10 0 0 0aBP .为气候动荡、发生逆转时期  相似文献   

南秦岭寒武-奥陶纪碳酸岩台地演化   总被引：1，自引：0，他引：1  

崔智林  孟庆仁 《沉积学报》1997,15(1):161-167

南秦岭早古生代碳酸岩台地属于扬子板块北部被动大陆边缘。台地经历了３个演化阶段:①下-中寒武统缓坡沉积阶段；②中寒武统-下奥陶统镶边陆棚沉积阶段；③中-上奥陶统混合陆棚沉积阶段。下志留统的进积陆源碎屑沉积淹没了全区。从台地相带的展布规律和古地理轮廓推测，早古生代时台地北侧可能存在一个已消失了的古陆。  相似文献   

DISSIPATION EFFECT ON THE FLOW OVER MOUNTAINS          下载免费PDF全文

伍荣生  方娟 《Acta Meteorologica Sinica》1997,(2)

In the paper,the turbulent dissipation is considered in the model for studying the flow overmountains.The governing equation is a first order ordinary differential equation derived from analgebraic equation without dissipation case.The solution is sensitive to the upstream condition ofdissipation.The dissipation not only reduces the strength of discontinuity but also changes theproperties of the governing equation.In the paper,the qualitative characteristic features of thegoverning equation are discussed.The numerical results with super and sub-critical cases are alsodiscussed in detail.The results show that the turbulent dissipation is an important factor and is notnegligible.  相似文献   

天山西部中山带积雪变化趋势与气温和降水的关系——以巩乃斯河谷为例   总被引：7，自引：0，他引：7  

张丽旭  魏文寿 《山地学报》2001,19(5):403-407

根据位于巩乃斯河谷的天山积雪雪崩研究站近30a来的年最大雪深、月平均气温、月降水量观测记录，用平均差值法、最小二乘法、自回归滑动平均法检验了天山西部中山带积雪、冷季降水、冷季平均气温的变化趋势，结果表明，天山西部中山带积雪呈增加趋势，近30a来年平均增加1．43％，与青藏高原、南极大陆及格陵兰冰盖表面积雪积累增加相一致。天山西部中山带冷季气温和降水的变化趋势也是增加的，其中冷季降水平年平均增加0．12％，而冷季气温升高了0．8℃，积雪与冷季气温之间存在着弱的负相关关系，而与冷季降水呈显著的正相关关系。积雪的增加主要是因为气候变暖引起的冷季降水的增加对积雪增加的贡献大于由于冷季气温升高而造成积雪减少的贡献的结果。  相似文献   

Columbia Mountain landslide: late-glacial emplacement and indications of future failure, Northwestern Montana, USA     

Larry N. Smith   《Geomorphology》2001,41(4)

The well preserved and undissected Columbia Mountain landslide, which is undergoing suburban development, was studied to estimate the timing and processes of emplacement. The landslide moved westward from a bedrock interfluve of the northern Swan Range in Montana, USA onto the deglaciated floor of the Flathead Valley. The landslide covers an area of about 2 km², has a toe-to-crown height of 1100 m, a total length of 3430 m, a thickness of between 3 and 75 m, and an approximate volume of 40 million m³. Deposits and landforms define three portions of the landslide; from the toe to the head they are: (i) clast-rich diamictons made up of gravel-sized angular rock fragments with arcuate transverse ridges at the surface; (ii) silty and sandy deposits resting on diamictons in an internally drained depression behind the ridges; and (iii) diamictons containing angular and subangular pebble-to block-sized clasts (some of which are glacially striated) in an area of lumpy topography between the depression and the head of the landslide. Drilling data suggest the diamictons cover block-to-slab-sized bedrock clasts that resulted from an initial stage of the failure.The landslide moved along a surface that developed at a high angle to the NE-dipping, thinly bedded metasediments of the Proterozoic Belt Supergroup. The exposed slope of the main scarp dips 30–37°W. A hypothetical initial rotational failure of the lower part of a bedrock interfluve may have transported bedrock clasts into the valley. The morphology and deposits at the surface of the landslide indicate deposition by a rock avalanche (sturzstrom) derived from a second stage of failure along the upper part of the scarp.The toe of the Columbia Mountain landslide is convex-west in planview, except where it was deflected around areas now occupied by glacial kettles on the north and south margins. Landsliding, therefore, occurred during deglaciation of the valley while ice still filled the present-day kettles. Available chronostratigraphy suggests that the ˜1-km thick glacier in the region melted before 12,000 ¹⁴C years BP—within 3000 years of the last glacial maximum. Deglaciation and hillslope failure are likely causally linked. Failure of the faceted interfluve was likely due tensile fracturing of bedrock along a bedding-normal joint set shortly after glacial retreat from the hillslope.Open surficial tension fractures and grabens in the Swan Range are limited to an area above the crown of the landslide. Movement across these features suggests that extensional flow of bedrock (sackung) is occurring in what remains of the ridge that failed in the Columbia Mountain landslide. The fractures and grabens likely were initiated during failure, but their morphologies suggest active extension across some grabens. Continued movement of bedrock above the crown may result in future mass movements from above the previous landslide scarp. Landslides sourced from bedrock above the scarp of the late-glacial Columbia Mountain landslide, which could potentially be triggered by earthquakes, are geologic hazards in the region.  相似文献   

阿尔泰中高山区域化探金异常成因探讨   总被引：1，自引：0，他引：1  

徐宁  李月臣 《新疆地质》2001,19(3):166-173

以异常查证和矿床成因研究成果为基础，在异常集／构造带的层次上分析了阿尔泰中高山区金异常的成因，认为异常主要由砂金引起，砂金来源于古风化壳－即古近纪以前的红土型金矿，终极来源可能为以含金石英脉为代表的分散矿化。据此分析，北阿尔泰带的岩金勘查前景应审慎评估，例外的是诺尔特亚带。在此基础上，提出了砂金成因异常的地球化学判别标志，并对冰缘区若干地球化学勘查问题进行了讨论。  相似文献   

嵩山旅游资源开发初探   总被引：7，自引：0，他引：7  

周峰 《地域研究与开发》2002,21(4):87-90

中岳嵩山有着数千年的文明史，蕴藏着丰富的自然旅游资源和人文旅游资源。然而，认识上的误区导臻嵩山旅游开发与其丰富的资源极不相称，嵩山进一步开发旅游业的潜力巨大，文章通过分析嵩山的自然旅游资源和人文旅游资源优势。以及资源特色。区域性特征，找出了目前开发中存在的问题，提出了加强包装和宣传促销，作好开发规划并分步实施，建立合理的旅游结构和围绕嵩山特色，搞好优势资源开发，以独特之处吸引游客等建议。  相似文献   

贺兰山北段晚石炭世和早二叠世植物群古生态研究   总被引：9，自引：6，他引：9  

孙克勤  张周良 《现代地质》1996,10(3):316-324,T002

对贺兰山北段呼鲁斯太和沙巴台地区晚石炭世和早二叠世植物化石进行了研究，共鉴定植物化石２０属４０种，讨论了植物群的性质和时代。在研究植物群特征基础上，分析了植物化石埋藏类型，论证了植物群的古生态特征，划分了５个植物群落：（１）Ｂｏｔｈｒｏｄｅｎｄｒｏｎｃｉｒｃｕｌａｒｅ群落；（２）Ｌｅｐｉｄｏｄｅｎｄｒｏｎｓｕｂｒｈｏｍｂｉｃｕｍ群落；（３）Ｌｅｐｉｄｏｄｅｎｄｒｏｎｓｚｅｉａｎｕｍ群落；（４）Ｔａｅ－ｎｉｏｐｔｅｒｉｓｍｕｃｒｏｎａｔａ群落；（５）Ｐｅｃｏｐｔｅｒｉｓｏｒｉｅｎｔａｌｉｓ群落。这５个植物群落的时代分别相当于晚石炭世早期、晚石炭世中期、晚石炭世晚期、早二叠世早期和早二叠世晚期。石松类植物在晚石炭世沼泽环境最为丰富，以华夏植物区大量的特有种为特征。而蕨类植物和种子蕨类植物在早二叠世的泥炭沼泽和泛滥平原环境占优势。这些植物群落在晚石炭世和早二叠世广泛分布在不同演化阶段的泥炭沼泽和碎屑低地环境，指示温暖潮湿的气候条件。  相似文献