新疆准噶尔晚古生代陆壳垂向生长（Ⅰ）——后碰撞深成岩浆活动的时限   总被引：71，自引：56，他引：71  

韩宝福  季建清宋彪  陈立辉张磊 《岩石学报》2006,22(5):1077-1086

准噶尔是新疆北部古生代造山带的重要组成部分，以广泛发育晚古生代后碰撞花岗岩为特征，是中亚造山带中显生宙陆壳生长作用非常显著的地区之一。根据新近获得的SHRIMP锆石U-Pb年龄，并参考已经发表的锆石U-Pb年龄，本文重新厘定了准噶尔晚古生代后碰撞深成岩浆活动的时限。按照最新的国际地质年表中石炭纪和二叠纪划分方案（Gradstein et a1．，2004），准噶尔后碰撞深成岩浆活动是从早石炭世中-晚维宪期开始、于早二叠世末期结束的。东准噶尔后碰撞深成岩浆活动发生在330-265Ma之间，而西准噶尔后碰撞深成岩浆活动的时限在340-275Ma之间，持续时间分别约65Ma。但是，在东准噶尔，后碰撞深成岩浆活动集中在330～310Ma和305～280Ma两个时段发生，而在西准噶尔，后碰撞深成岩浆活动的高峰发生在310～295Ma之间。准噶尔晚古生代后碰撞深成岩浆活动在空间上没有受到重要地质界线（如蛇绿岩带）的分隔控制，在有的地方花岗岩还可以侵位在蛇绿岩带之中。而晚古生代后碰撞深成岩浆活动不但在准噶尔分布广泛，而且在准噶尔北邻的阿尔泰造山带和南邻的天山造山带中均有出现，具有广泛的区域性。  相似文献   

阿尔泰中蒙边界塔克什肯口岸后造山富碱侵入岩体的形成时代、成因及其地壳生长意义   总被引：23，自引：14，他引：23  

童英  王涛  V P Kovach  洪大卫  韩宝福 《岩石学报》2006,22(5):1267-1278

塔克什肯口岸富碱侵入岩体是阿尔泰造山带典型的后造山岩体。本次锆石U-Pb定年给出~(206)Pb/~(238)U年龄286±1Ma(MSWD=0．05),代表其形成年龄。这为阿尔泰后造山岩浆作用提供了一个可靠的年代学证据。该岩体主要岩石类型为正长岩、石英二长岩、石英碱长正长岩、正长花岗岩,富钾、富钠、准铝,富集轻稀土、大离子亲石元素,亏损高场强元素,与区内相邻的碱性花岗岩(A型花岗岩)在岩石学、地球化学方面不同。该岩体Sr初始值变化于0．7038～0．7040,ε_(Nd)(t)值为正值(+6．2～+6．3),Nd模式年龄T_(DM)为542～546Ma,与中亚造山带典型的高(正)ε_(Nd)(t)值花岗岩类似。而且,其ε_(Nd)(t)值远高于区内同造山花岗岩,也高于造山带内部同时期的Ⅰ-A型后造山花岗岩。依据岩体构造特征、年代学、地球化学和区域地质背景综合分析,该岩体应为后造山岩体,在时空上可与蒙古南部碱性岩带对比,其形成可能与富集高场强元素的亏损地幔岩浆底侵,导致下地壳重熔,并发生岩浆混合有关。这说明,在阿尔泰造山带后造山阶段,除了可能的俯冲下埋的年轻洋壳或岛弧物质外,还有新的幔源物质加入到地壳。这为中亚造山带后造山阶段陆壳垂向生长提供了一个新证据。同时,也为东北北部-蒙古南部碱性岩带向西沿入阿尔泰造山带提供了证据。  相似文献   

Monitoring urban growth on the European side of the Istanbul metropolitan area: A case study     

S. Kaya  P.J. Curran 《International Journal of Applied Earth Observation and Geoinformation》2006

Istanbul is the largest city in Turkey with an area of around 5750 km² and a population of around 10.8 M (2000). In 1980, the population was only around 4.7 M and so has more than doubled in only 2 decades. In 2000, around 65% of the population were living on the European side of the city with its large industrial/commercial and trade centres. The population is increasing as a result of both births exceeding deaths and mass immigration. Consequently, planned and unplanned housing are increasing while green areas are decreasing in area. Monitoring urban growth will enable the Municipality of Istanbul to better manage this complex urban area.  相似文献   

Growth of Barents Sea capelin (Mallotus villosus) in relation to zooplankton abundance     

Gjosaeter  Harald; Dalpadado  Padmini; Hassel  Arne 《ICES Journal of Marine Science》2002,59(5):959-967

  相似文献   

基于NDVI与LAI的水稻生长状况研究     

彭虓  张树文 《测绘与空间地理信息》2002,25(4):16-19

在水稻反射光谱特性与水稻生物参数关系的支持下 ,以吉林省德惠市夏家点镇为研究区 ,探讨了一条基于TM遥感影像反演得到的归一化植被指数 (NDVI)与地面观测数据叶面积指数 (LAI)的水稻生长状况的研究途径 ,并利用NDVI以及LAI对该区 2 0 0 0年和 2 0 0 1年的水稻生长状况进行了分析研究。  相似文献   

水稻干物质的数值模拟及类型区划   总被引：2，自引：0，他引：2  

高永刚  王飞 《南京气象学院学报》1998,21(4):637-646

干物质积累是水稻经济产量的基础,利用分斯播种资料,运用作物生长模拟方法,根据水稻主要种植区域的光温资料,作出水稻干物质积累的理论计算。通过对干物质积累值的时空规律分析和区划,为分析生物学产量形成的生态条件提供数据。  相似文献   

不同气候生态棉区化学调控适宜期的试验及其应用   总被引：2，自引：1，他引：1       下载免费PDF全文

薛晓萍史可琳  王建林 《应用气象学报》1998,9(3):371-375

在山东省气候条件下,棉花生长发育主要受热量条件制约．由积温推算出在不同气候生态棉区以及不同品种、种植方式、密度和产量水平下的棉田物候期,由此得到相应棉田各次化调期,可改变田间小气候,提高成铃率１０％～１５％,单铃重增加０．３～０．９ｇ,使棉田因蕾期缩短而改变播期及种植品种,扩大麦棉两熟种植区域,提高棉花品质．  相似文献   

Idealized simulation of the Colorado hailstorm case: comparison of bulk and detailed microphysics     

I. Geresdi 《Atmospheric Research》1998,45(4):237-252

One of the purposes of the Fourth Cloud Modeling Workshop was to compare different microphysical treatments. In this paper, the results of a widely used bulk treatment and five versions of a detailed microphysical model are presented. Sensitivity analysis was made to investigate the effect of bulk parametrization, ice initiation technique, CCN concentration and collision efficiency of rimed ice crystal–drop collision. The results show that: (i) The mixing ratios of different species of hydrometeors calculated by bulk and one of the detailed models show some similarity. However, the processes of hail/graupel formation are different in the bulk and the detailed models. (ii) Using different ice initiation in the detailed models' different processes became important in the hail and graupel formation. (iii) In the case of higher CCN concentration, the mixing ratio of liquid water, hail and graupel were more sensitive to the value of collision efficiency of rimed ice crystal–drop collision. (iv) The Bergeron–Findeisen process does not work in the updraft core of a convective cloud. The vapor content was always over water saturation; moreover, the supersaturation gradually increased after the appearance of precipitation ice particles.  相似文献   

Experimental simulations of gas-driven eruptions: kinetics of bubble growth and effect of geometry     

Youxue Zhang 《Bulletin of Volcanology》1998,59(4):281-290

 Simulated gas-driven eruptions using CO₂–water-polymer systems are reported. Eruptions are initiated by rapidly decompressing CO₂–saturated water containing up to 1.0 wt.% CO₂. Both cylindrical test cells and a flask test cell were used to examine the effect of magma chamber/conduit geometry on eruption dynamics. Bubble-growth kinetics are examined quantitatively in experiments using cylindrical test cells. Uninhibited bubble growth can be roughly expressed as dr/dt≈λD(β-1)/(γt ^1/3) for a CO₂–water-polymer system at 0–22  °C and with viscosities up to 5 Pa·s, where r is the radius of bubbles, λ and D are the Ostwald solubility coefficient and diffusivity of the gas in the liquid, β is the degree of saturation (decompression ratio), and γ characterizes how the boundary layer thickness increases with time and is roughly 1.0×10^–5 m/s^1/3 in this system. Unlike the radius of cylindrical test cells, which does not affect the eruption threshold and dynamics, the shape of the test cells (flask vs cylindrical) affects the dynamics but not the threshold of eruptions. For cylindrical test cells, the front motion is characterized by constant acceleration with both Δh (the height increase) and ΔV (the volume increase) being proportional to t ²; for the flask test cell, however, neither Δh nor ΔV is proportional to t ² as the conduit radius varies. Test-cell geometry also affects foam stability. In the flask test cell, as it moves from the wider base chamber into the narrower conduit, the bubbly flow becomes fragmented, affecting the eruption dynamics. The fragmentation may be caused by a sudden increase in acceleration induced by conduit-shape change, or by the presence of obstacles to the bubbly flow. This result may help explain the range in vesicularities of pumice and reticulite. Received: 16 May 1997 / Accepted: 11 October 1997  相似文献   

Damage to structures by pyroclastic flows and surges, inferred from nuclear weapons effects     

Greg A. Valentine 《Journal of Volcanology and Geothermal Research》1998,87(1-4)

In order to define the risk from explosive eruptions, one must constrain both the probability of explosive events and the effects, or consequences, of those events. This paper focuses on the effects of pyroclastic flows and surges (here termed ‘pyroclastic density currents', or PDCs) on buildings, infrastructure elements, and to some extent on vehicles. PDCs impart a lateral force to such structures in the form of dynamic pressure, which depends on the bulk density of the PDC (which in turn depends mainly on particle concentration) and its velocity. For reasonable ranges of particle concentration (10⁻³ to 0.5) and velocities (10 to 300 m/s), dynamic pressure on the upstream face of a structure ranges from 0.1 kPa to 10⁴ kPa. Lateral loads ranging up to about 100 kPa were produced during nuclear weapons tests in the 1940s and 1950s that were designed to study the effects of such loading on a variety of structures for civil defense and emergency response purposes in the event of nuclear war. Although considerable simplifications are involved, the data from these weapon tests provide useful analog information for understanding the effects of PDCs. I reviewed data from the nuclear tests, describing the expected damage from different loadings. Tables are provided that define the response of different structural elements (e.g., windows, framing, walls) and whole structures to loading in probabilistic terms, which in principle account for variations in construction quality, orientation, and other factors. Finally, damage documented from historical eruptions at Mt. Lamington (1951), Herculaneum (AD 79 Vesuvius eruption), and St. Pierre (1902 Mt. Pelee eruption) is reviewed. Damage patterns, combined with estimates of velocity, provide an independent estimate of particle concentration in the PDCs. Details of structural damage should be recorded and mapped around future eruptions in order to help refine this aspect of consequence analysis. Another fruitful approach would be to combine numerical simulations of eruption scenarios, which can produce simulated maps of dynamic pressure, with GIS-based data on structures for a given region; the result would be predictions of consequences that could be used for planning and emergency response training.  相似文献