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An automatic weather station(AWS) has been installed at the Qomolangma Station of the China Academy of Sciences(QOMS) since 2005, in a northern Himalayan valley near Mount Everest, with an altitude of 4,270 m a.s.l.. Nine years of meteorological records(2006–2014) from the automatic weather station(AWS) were analyzed in this study, aiming to understand the response of local weather to the seasonal transition on the northern slopes of Mount Everest, with consideration of the movement of the subtropical jet(STJ) and the onset of the Indian Summer Monsoon(ISM). We found:(1) Both the synoptic circulation and the orography have a profound influence on the local weather, especially the local circulation.(2) Southwesterly(SW) and southeasterly(SE) winds prevail alternately at QOMS in the afternoon through the year. The SW wind was driven by the STJ during the non-monsoon months, while the SE was induced by the trans-Himalayan flow through the Arun Valley, a major valley to the east of Mount Everest, under a background of weak westerly winds aloft.(3) The response of air temperature(T) and specific humidity(q) to the monsoon onset is not as marked as that of the nearsurface winds. The q increases gradually and reaches a maximum in July when the rainy period begins.(4) The alternation between the SW wind at QOMS and the afternoon SE wind in the pre-monsoon season signals the northward shift of the STJ and imminent monsoon onset. The average interval between these two events is 14 days. 相似文献
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西昆仑柳什塔格峰西侧火山岩的特征、时代及地质意义 总被引：1，自引：0，他引：1
在西昆仑麻扎-康西瓦-苏巴什结合带的柳什塔格一带发现了一套火山岩建造,主要由强蚀变玄武岩、绿帘阳起石岩、阳起石岩(原岩为玄武岩)组成,上覆少量深水沉积岩。火山岩的岩石地球化学特征表明其主要来源于富集地幔玄武岩浆,形成于洋岛环境,因此它是一个古结合带大洋洋壳的残留。采样作Rb-Sr等时线年龄分析,时代为震旦纪(563±48Ma),说明麻扎-康西瓦-苏巴什结合带所代表的洋盆在震旦纪就已经存在。这个发现对重新认识麻扎-康西瓦-苏巴什结合带的演化时限具有重要意义。 相似文献
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MaoShan Li YaoMing M WeiQiang M Ishikawa Hirohiko FangLin Sun Shinya Ogino 《寒旱区科学》2011,3(6):0509-0516
In this paper, based on in-situ observational data of the Coordinated Enhanced Observing Period (CEOP) Asia-Australia
Monsoon Project (CAMP) on the Tibetan Plateau (CAMP-Tibet), structure of the Atmospheric Boundary Layer (ABL) was
preliminarily studied during the dry and rainy seasons. The main results show: (a) Diurnal variation of the ABL is obvious over
the northern Tibetan Plateau area. The height of the ABL is different with the season change, which ranges from 2,211 m to
4,430 m during the pre-monsoon season and from 1,006 m to 2,212 m during the monsoon season. The ABL height is higher
during the dry period than during the rainy period. (b) The humidity is lower during the dry period than during the rainy period,
and there are reverse humidity during both periods. (c) Horizontal wind direction is mostly west during the dry period, east
under the height of 2,500 m and west above the height of 2,500 m during the rainy period. The wind speed is low during both
the rainy and dry periods in the lower ABL layer. The wind speed is stronger within the upper ABL during the dry period than
during the rainy period. 相似文献
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秦岭造山带泥盆系形成构造环境：来自碎屑岩组成和地球化学方面的约束 总被引：4，自引：12，他引：4
秦岭造山带中分布于商丹和勉略缝合带之间的泥盆系,发育有众多Au、Ag和Pb-Zn矿床,长期以来备受关注。对于泥盆系物源和形成环境认识始终存在不同认识。砂岩碎屑组成、碎屑重矿物、地球化学成分、砾岩组成以及古水流研究表明,北秦岭是秦岭泥盆系的主要物源区,盆地基底隆起也是泥盆系重要物源区。砂岩碎屑组成、碎屑重矿物和砾岩组成表明,泥盆系物源区曾出露有岛弧火山岩、花岗岩、变质岩及少量沉积岩、超镁铁岩。砂岩地球化学成分和砂岩碎屑模式研究表明,秦岭造山带中泥盆系主要形成于活动大陆边缘,其碎屑沉积物来自多种构造环境中的岩石单元。 相似文献
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辽西义县组顶部层位为义县组金刚山层之上的黄花山角砾岩层或流纹岩(二者为同时异相).通过对该流纹岩样品中锆石的LA-ICP-MS的U-Pb测年,获得其加权平均年龄为(118.9±1.4)Ma～(119.8±1.9)Ma.通过Ar-Ar方法测年,测得了黄花山角砾岩层的下部岩石中灌入的英安斑岩的年龄,其坪年龄为(122.1±0.3)Ma,等时线年龄为(121.8±1.4)Ma.反映义县组顶部层位的形成时期应在122～119Ma.义县组顶部层位年龄的确定,不仅确定了义县组中热河动物群顶部层位(金刚山层)的上限年龄(约122Ma),同时也确定了义县组火山岩形成的上限年龄(118.9±1.4)Ma～(119.8±1.9)Ma.该地区义县组顶部层位的年龄,也是辽西乃至中国东北地区白垩纪大规模岩浆活动结束的年龄. 相似文献
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陕西凤县八方山-二里河大型铅锌矿床地球化学特征及找矿预测 总被引：4，自引：3，他引：1
八方山-二里河大型铅锌矿床具有热水沉积和后期改造的成矿特征,但REE、B、Ba、Tl等元素的分布特征不完全具有明显海底喷流特征,或者说其距喷流中心较远。该矿床石英流体包裹体均一温度和闪锌矿中FeS中分子百分数及Ga/Ge原子比均显示成矿温度为200~340℃,以中、高温为主。方解石流体包裹体均一温度为80~160℃和160~260℃,反映有两次热液事件的改造作用。矿区矿化硅质岩中的锆石具有碎屑锆石的特点,U-Pb年龄值分散(400~1800Ma),不能代表硅质岩或铅锌矿床的形成时代,大量碎屑锆石的存在说明其形成环境可能是近海成因。破坏铅锌矿体的闪长玢岩的形成时代为214±2Ma,二里河矿区附近的花岗斑岩形成时代为217.9±4.5Ma,二者皆是印支运动晚期的产物。闪长玢岩切穿矿体和微石英岩,说明矿化改造作用应在此之前;矿体在背斜的转折端富集,说明改造作用的主体应在褶皱过程中发生,即印支运动早期是矿化改造期,也可能是印支早期至印支晚期之间。八方山-二里河大型铅锌矿床的形成经历了热水沉积和构造改造2个成矿阶段,沉积阶段金属元素在中泥盆世地层中形成初步富集,为后期构造改造提供了物质来源。该矿床成因为基底热水喷流沉积-构造岩浆改造型。本区铅锌矿床的主要控矿构造应为同沉积背斜、提供热水运移通道的同生断裂构造及成矿物质沉淀富集的局限性沉积盆地构造。同沉积灰岩背斜、灰岩与千枚岩接触带以及硅质岩或者碳酸盐岩地层区的"礁-硅-泥"岩套是最直接、最重要的找矿标志。八方山-二里河铅锌矿区扩大找矿的最经济且有储量远景的地段是主背斜南翼TEM物探异常部位,这是为矿山寻找可接替资源的最佳勘查靶位。 相似文献
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辽西阜新-义县盆地及附近地区早白垩世地壳大规模减薄及成因探讨 总被引：24，自引：2，他引：22
辽西阜新-义县盆地及其附近地区,其早白垩世的地层、构造和火山岩有明显的特殊性。在地层方面,阜新-义县盆地内下白垩统分布较齐全,而土城子组及以前的侏罗系基本缺失,反映在义县期之前,阜新-义县盆地处在剥蚀环境中（正地形）,而在早白垩世处在快速沉降的沉积环境中（负地形）,并在早白垩世沉降了约7km。构造方面,晚侏罗世末期,褶皱、逆冲作用反映研究区发生了一定规模的挤压抬升作用;早白垩世阜新-义县盆地的伸展断陷作用贯穿始终,也说明了该地区早白垩世快速沉降的存在。在火山岩方面,阜新-义县盆地及附近地区的义县组下部多处分布有含镁较高的火山岩,其地球化学特征反映该火山岩岩浆源于地幔,同时有复杂的成因,这提供了阜新-义县盆地及附近地区早白垩世地壳大规模减薄、地幔岩浆上涌的信息。以上地质特征说明,早白垩世阜新-义县盆地发生了与地幔作用有关的大规模地壳减薄作用。 相似文献
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