Comparison of Different Generation Mechanisms of Free Convection between Two Stations on the Tibetan Plateau     

Lang ZHANG  Yaoming MA  Weiqiang MA  Binbin WANG 《大气科学进展》2018,35(9):1137-1144

Based on high-quality data from eddy covariance measurements at the Qomolangma Monitoring and Research Station for Atmosphere and Environment(QOMS) and the Southeast Tibet Monitoring and Research Station for Environment(SETS),near-ground free convection conditions(FCCs) and their characteristics are investigated. At QOMS, strong thermal effects accompanied by lower wind speeds can easily trigger the occurrence of FCCs. The change of circulation from prevailing katabatic glacier winds to prevailing upslope winds and the oscillation of upslope winds due to cloud cover are the two main causes of decreases in wind speed at QOMS. The analysis of results from SETS shows that the most important trigger mechanism of FCCs is strong solar heating. Turbulence structural analysis using wavelet transform indicates that lowerfrequency turbulence near the ground emerges from the detected FCCs both at QOMS and at SETS. It should be noted that the heterogeneous underlying surface at SETS creates large-scale turbulence during periods without the occurrence of FCCs. Regarding datasets of all seasons, the distribution of FCCs presents different characteristics during monsoonal and non-monsoonal periods.  相似文献   

广东省“人口—经济—土地—社会—生态”城市化协调度时空变化及其聚类模式   总被引：1，自引：0，他引：1  

李久枫  余华飞  付迎春  赵耀龙 《地理科学进展》2018,37(2):287-298

多维城市化协调度评价是衡量区域城市化质量的重要方面,探究城市化时空聚类模式则是分析区域城市化特征的有效方法。针对目前城市化协调度评价缺乏多维度时空综合分析的现状,本文以广东省为例,提出一种基于时空权重矩阵的复杂时空系统协调度评价模型,运用此模型分析2006-2014年城市化协调度的时空变化特征,并借助时空扫描方法分析其聚类模式。研究结论为：①近10年来城市化水平呈现3种时序特征,人口城市化水平表现出随时间均衡发展的“集中”特征,而经济与土地表现出低频次的“集中与分散”交替,社会、生态及综合水平表现出高频次的“集中与分散”交替;稳定型城市主要位于珠三角核心区。②各维度及综合系统协调度时空聚类区既有空间分异性又有重叠性,人口协调度时空聚类于粤西地区,经济与土地维度协调度时空聚类高度重合于珠三角与粤北地区,社会与生态维度协调度时空聚类交叉于珠三角与粤东地区,而综合系统协调度居中。此外,时空聚类区的人口、经济与社会维度的协调度稳定性要优于土地与生态维度。本文结论有助于揭示区域城市化的时空特征。  相似文献   

一次台风移出后MCC发展成因分析     

刘晓波  孙军  许映龙  陈双 《热带气象学报》2023,(2):205-217

应用FY-4A卫星云顶亮温(TBB)、自动站雨量资料和ERA5(0.25°×0.25°)再分析资料,对2020年第4号台风“黑格比”移出后在杭州湾生成MCC发展成因进行了分析。结果表明：(1)台风南侧的切变线辐合抬升作用以及南亚高压东部反气旋环流辐散抽吸作用,有利于中低空大气上升运动的增强,为MCC的发展增强提供良好的动力抬升条件;(2)低层台风北上后,其移动方向左后侧的冷空气南下,并与长三角地区的西南低空暖湿气流强烈交汇,斜压锋生增强,形成较强的上升运动;（3）受大陆高压东移影响,对流层中高层干冷空气东移,叠加在对流层中低空暖湿急流之上,形成了有利于MCC发生发展的大气位势不稳定层结;(4)切变线南端的西南低空急流不仅加强了低层大气的辐合和上升运动,更重要的是为MCC的发生发展提供丰富的水汽输送和汇聚;(5)水汽凝结潜热释放在MCC发展中起重要作用。水汽释放潜热加热大气,使上升运动增强,低层辐合进一步增强。低层水汽汇聚并不断向高空输送,补偿了高空凝结的水汽,潜热的不断释放,有利于MCC发展和维持。总之,台风中心移出后,台风南侧的切变线及其南侧的西南暖湿气流稳定地维持在MCC上空,为M...  相似文献   

Interaction in the water-rock system as a new basis for the development of hydrogeology     

S. L. Shvartsev 《Russian Journal of Pacific Geology》2008,2(6):465-475

This paper addresses the main mechanisms controlling the continuous and geologically long evolution of the water-rock system, which produced diverse hydrogenous mineral complexes. The concept of such complexes was introduced by the author. It was shown that the water-rock system is a steady-state and equilibrium-disequilibrium one. Its development occurs in a far from equilibrium region and results in the formation of fundamentally new mineral associations and geochemical types of water. Taking into account that water is the main factor controlling the evolutionary trend of this system, it is argued that this system must be among the most important targets of hydrogeology.  相似文献   

The Oneka intrusive complex: a new structural type of large-scale manifestations of intrusive trap magmatism on the Siberian Platform     

Yu.R. Vasil''ev  S.N. Prusskaya  M.P. Mazurov  A.Ya. Medvedev  A.I. Al''mukhamedov  M.P. Gora 《Russian Geology and Geophysics》2008,49(5):297-309

The Oneka intrusive complex, recognized on prospecting for hydrocarbons in the western Siberian Platform, in the northern half of the Bakhta megablock (Tunguska syneclise), holds a special position among the known and new large-scale manifestations of intrusive trap magmatism. During the process, original data on the distribution of traps in the 4.2 km thick platform cover were obtained. Diverse in morphology and size, the intrusions are of the same genesis, composition, and character of intrachamber differentiation and form a “framework” igneous complex in the northern half of the Bakhta megablock. This complex occupies an area of about 40,000 km². It is an intricate tectonomagmatic superstructure, with the volume of magmatic material estimated at 50,000 km³. Results of petrochemical and geochemical studies, multispectra and REE ratios, and isotope ratios ⁸⁷Sr/⁸⁶Sr (0.70558–0.70580) suggest that diverse rocks of the Oneka intrusive complex were, most likely, formed from a primary picritoid magma, which underwent deep-level differentiation and was slightly contaminated with rocks of the crust and platform cover. The comprehensive study of the massif and results of numerical modeling show that the formation of such tectonomagmatic structures is closely related to the processes of intraplate magma formation in the craton lithosphere. The large Oneka intrusive complex, like other similar manifestations of Permo-Triassic trap (and alkaline-ultrabasic) magmatism of the Siberian Platform, can be considered projections of hotspots recording the evolution of the Siberian superplume.  相似文献   

Deep‐water foreland basin deposits of the Cerro Toro Formation,Magallanes basin,Chile: architectural elements of a sinuous basin axial channel belt     

STEPHEN M. HUBBARD  BRIAN W. ROMANS  STEPHAN A. GRAHAM 《Sedimentology》2008,55(5):1333-1359

Coarse‐grained deep‐water strata of the Cerro Toro Formation in the Cordillera Manuel Señoret, southern Chile, represent the deposits of a major channel belt (4 to 8 km wide by >100 km long) that occupied the foredeep of the Magallanes basin during the Late Cretaceous. Channel belt deposits comprise a ca 400 m thick conglomeratic interval (informally named the ‘Lago Sofia Member’) encased in bathyal fine‐grained units. Facies of the Lago Sofia Member include sandy matrix conglomerate (that show evidence of traction‐dominated deposition and sedimentation from turbulent gravity flows), muddy matrix conglomerate (graded units interpreted as coarse‐grained slurry‐flow deposits) and massive sandstone beds (high‐density turbidity current deposits). Interbedded sandstone and mudstone intervals are present locally, interpreted as inner levée deposits. The channel belt was characterized by a low sinuousity planform architecture, as inferred from outcrop mapping and extensive palaeocurrent measurements. Laterally adjacent to the Lago Sofia Member are interbedded mudstone and sandstone facies derived from gravity flows that spilled over the channel belt margin. A levée interpretation for these fine‐grained units is based on several observations, which include: (i) palaeocurrent measurements that indicate flows diverged (50° to 100°) once they spilled over the confining channel margin; (ii) sandstone beds progressively thin, away from the channel belt margin; (iii) evidence that the eroded channel base was not very well indurated, including a stepped margin and injection of coarse‐grained channel material into surrounding fine‐grained units; and (iv) the presence of sedimentary features common to levées, including slumped units inferring depositional slopes dipping away from the channel margin, lenticular sandstone beds thinning distally from the channel margin, soft sediment deformation and climbing ripples. The tectonic setting and foredeep architecture influenced deposition in the axial channel belt. A significant downstream constriction of the channel belt is reflected by a transition from more tabular units to an internal architecture dominated by lenticular beds associated with a substantially increased degree of scour. Differential propagation of the fold‐thrust belt from the west is speculated to have had a major control on basin, and subsequently channel, width. The confining influence of the basin slopes that paralleled the channel belt, as well as the likelihood that numerous conduits fed into the basin along the length of the active fold‐thrust belt to the west, suggest that proximal–distal relationships observed from large channels in passive margin settings are not necessarily applicable to axial channels in elongate basins.  相似文献   

西藏东部嘉玉桥变质杂岩内中侏罗世高压剪切作用:来自多硅白云母的证据   总被引：5，自引：2，他引：3  

王根厚  张维杰  周详  贾建称  于海亮 《岩石学报》2008,24(2)

藏东嘉玉桥变质杂岩分布于班公错-怒江缝合带南西,出露宽度约15～20km,延伸长度约120km。藏东嘉玉桥变质杂岩与上覆中侏罗统呈滑脱断层接触,滑脱带内发育各种韧性剪切组构。滑脱带内钠长石英构造片岩中石英呈矩形条带,多硅白云母与石英矩形条带构成S-C组构,石英颗粒应变测量表明Flinn图解K=∞,代表近水平伸展滑脱。获得多硅白云母变质条件相当于蓝片岩相,压力属于高压变质相,多硅白云母测年结果为167.27±0.99 Ma,为中侏罗世高压剪切作用,暗示班公-怒江缝合带中侏罗世伸展与高压剪切作用密切相关。  相似文献   

锆石中钛温度计在鲁西—苏北地区中生代侵入杂岩中的应用   总被引：4，自引：1，他引：3  

王清海  许文良  杨德彬  裴福萍 《岩石学报》2008,24(10):2331-2342

利用锆石中钛地质温度计对鲁西—苏北地区出露的8个中生代侵入杂岩的岩浆岩结晶温度进行计算,结果表明研究区斑井岩体的平均岩浆结晶温度为715~716℃,蔡山岩体为653℃,丰山岩体为697℃,夹沟岩体为711℃,利国岩体为737℃,铁铜沟岩体为766℃,上峪岩体为889℃,金岭岩体为770℃。岩体的岩浆结晶温度沿侵入杂岩带展布方向,从S到N依次增高,暗示其岩浆起源深度逐渐加大。岩浆结晶温度计算结果大致限定了各岩体的岩浆源区深度范围,结合锆石寄主岩石和寄主岩石中的深源包体的研究表明研究区中生代侵入杂岩体的母岩浆起源于上地幔和/或下地壳。  相似文献   

阿尔金造山带南缘岩浆混合作用:玉苏普阿勒克塔格岩体岩石学和地球化学证据   总被引：16，自引：8，他引：8  

王超  刘良  张安达  杨文强  曹玉亭 《岩石学报》2008,24(12):2809-2819

阿尔金造山带南缘玉苏普阿勒克塔格岩体中的似斑状中粗粒黑云钾长花岗岩发育有岩浆成因的暗色包体,并且该花岗岩被花岗细晶岩呈脉状侵入。该岩体含有丰富的岩浆混合作用特征: 如暗色包体中的碱性长石斑晶、针状磷灰石、长石的环斑结构、石英/斜长石主晶和榍石眼斑等。暗色包体、寄主花岗岩和花岗细晶岩代表了岩浆混合演化过程中不同端元比例混合的产物。地球化学特征上,钾长花岗岩和暗色包体的主要氧化物含量在Harker图解中多呈线性变化。暗色包体主要为闪长质,MgO、K₂O含量高,为钾玄岩系列,总体上高场强元素不亏损,显示了岩浆混合中的基性端元信息,可能为幔源熔体结晶分异或壳幔物质的混合产物。寄主花岗岩均为准铝质,富碱,为高钾钙碱性系列,亏损Nb、Ta、Sr、P、Ti等高场强元素,高K₂O/Na₂O,富集高不相容元素,Ga含量高,显示了A型花岗岩的特征,Th/U 和Nb/Ta比值分别介于为6.67~10.96、8.99~11.94,代表了下地壳源区。花岗细晶岩均为钠质、过铝质,TiO₂、MgO含量低, Na₂O和CaO含量高,具有混合岩浆侵位后分异的特征。岩相学和地球化学特征说明岩浆混合作用对于环斑结构花岗岩的形成起到重要作用。花岗细晶岩中环斑长石的斜长石外环与钾长石内核的厚度比大于钾长花岗岩中的环斑长石,指示混合岩浆在一定的减压条件下更有利于环斑结构的形成。玉苏普阿勒克塔格岩体中的钾玄质暗色包体、高钾钙碱性花岗岩和中钾钙碱性花岗细晶岩代表了岩浆演化不同阶段的产物,反映了一个幔源岩浆和下地壳不断相互作用,引起地壳连续伸展减薄的过程,指示阿尔金南缘在早古生代末期存在造山后伸展背景下的幔源岩浆底侵作用。同一岩体中两种不同时代岩性的环斑结构显示了该岩体形成历史中的一定时空演化关系,代表了伸展过程中不同阶段的产物。  相似文献   

金矿复杂地层金刚石取心钻头选型试验研究          下载免费PDF全文

孙丙伦  孙友宏  徐良 《探矿工程》2008,35(8):70-72,76

金矿复杂地层金刚石钻进存在岩石坚硬、地层打滑、漏失等问题,影响钻头寿命和钻进效率。在山东招远某金矿勘探中,通过对3个单位制造的金刚石钻头进行现场对比试验研究,证明JBD-75S仿生金刚石钻头在提高钻头寿命方面具有较大的优越性,适合该复杂地层钻进。  相似文献