青海可可西里地区新生代火山岩研究

可可西里新生代火山岩主要出露在昆南断裂以南和东经９２°３０′以西的区域内，基本沿近东西走向的大型逆冲－走滑断裂带分布，可分为渐新世、中新世两期。渐新世熔岩的斑晶矿物组合为拉长石－透辉石－顽火辉石，中新世熔岩的为中长石－次透辉石（包括少量透辉石、普通辉石）－古铜辉石。总体而言这些火山岩富碱高钾（Ｋ２Ｏ＞３％，Ｋ２Ｏ／Ｎａ２Ｏ＞１），普遍富集大离子亲石元素，稀土元素含量很高并且轻重稀土比值很大。渐新世火山岩为高钾钙碱性系列，中新世岩石属于钾玄岩系。前者的微量元素和稀土元素的含量以及轻重稀土比均低于后者。所有岩石均具有较高的Ｓｒ同位素（＞０．７０７）和相对较低的Ｎｄ同位素（＜０．５１２４）组成，表现出源区曾受到年轻地壳的影响。高钾钙碱性岩系和钾玄岩系的岩石是大陆碰撞造山后期岩浆作用的产物。始新世以来，随着该区由碰撞、挤压作用发展到出现走滑，应力环境由挤压转变为张性，导致依次喷发高钾钙碱性岩系熔岩和钾玄岩系熔岩，在岩浆演化过程中这两个岩系则沿相同的趋势发展     

天津市夜间城市热岛的数值模拟

本文基于Myrap等人的工作,提出了一个能量平衡模式,并用实测的天津市夜间近地面温度场对模式进行了验证.应用这个模式,可给出天津市近地面热岛的适当预报,同时,可对天津市夜间城市热岛中各能量通量的空间变化进行讨论.     

兰州百合(Lilium davidii var.unicolor)的花粉活力、柱头可授性及繁育系统

为了探讨兰州百合(Lilium davidii var. unicolor)自然结实率低的原因,以"兰百1号"为试材,利用TTC(2,3,5-氯代三苯基四氮唑)染色法、离体萌发法测定花粉活力,以联苯胺-过氧化氢法测定柱头可授性,通过杂交指数、花粉-胚珠比和人工授粉试验对其繁育系统进行研究。结果表明:兰州百合开花当天08:00—14:00花粉活力较高,10:00左右花粉萌发率最高,可达78.31%;在开花当天08:00—12:00柱头可授性最强;花粉萌发时期与柱头可授时期基本重叠。杂交指数4,花粉-胚珠比2 195～4 836,自花授粉、同株异花授粉花败育率100%,异株异花授粉花败育率50%,结实率40%。兰州百合繁育系统为专性异交、自交不亲和、传粉过程需要传粉者。     

南极海冰和极涡指数的时空特征及相互关系

本文采用聚类分析方法将南极海冰距平划分成５个变化相似的区域。并计算了对应各区的南半球５００ｈＰａ极涡面积和强度指数。分析了海冰与极涡指数的时空特征及相互关系。结果表明，不同区域的海冰和极涡的气候特征和年际变化的差异十分显著。１区和４区的海冰变化最大。海冰范围和极涡指数在多数区都在２－２．５ａ和５－７ａ的振荡周期。仅发现１区海冰范围是扩张趋势，其他４个区都呈收缩趋势。南极平均海冰范围以１．６个纬度／     

非定常过程对大气边界层的内参数与风廓线的影响(二)

本文用大气边界层运动方程的数值积分研究了当边界层顶风向不变但风速变化时对大气边界层的内参数u_*/A(u_*为摩擦速度,A为上界风速)和α角(地面风与上界风向的交角)的影响。设上界处风速随时间指数增加及减少,最后趋于定常。在大气正、斜压时,u_*/A及α角的时间变化均是振幅衰减的振荡,最后趋于定常时相应的值。在时间变化过程中的任一时刻,内参数值与当上界条件取该时刻上界风时的定常解结果有一定的差别,严格说,定常时的内参数值并不能直接用于当上界风非定常时。本文还考虑了上界风速非定常对风廓线的影响。     

The Cretaceous volcanic succession around the Songliao Basin,NE China: relationship between volcanism and sedimentation

With volume ratio of 8:1:1.5 amongst acidic, intermediate and basaltic rocks, the Cretaceous volcanics around the Songliao Basin are a series of high‐K or medium‐K, peraluminous or metaluminous, calc‐alkaline rocks, lacking typical basalts and peralkaline members of typical rift‐related types. Their eruption ages range between 133 and 127 Ma, 124 and 122 Ma and 117 and 113 Ma respectively. They are high in total (Rare earth element) REE contents (96.1–326 ppm), enriched in LREE and depleted in HREE (LREE/HREE = 4.6–13.8), with negative Eu and Ce anomalies (Eu/Eu* = 0.04–0.88; Ce/Ce* = 0.60–0.97). They have enriched large‐ion lithophile elements (e.g. K, Ba, Th) and depleted high field strength elements (e.g. Nb, Ti and Y), suggesting a subduction‐related tectonic setting. The volcanic activities migrated from south to north, forming a successively northward‐stepping volcanic series and showing a feature significantly different from the overlying sedimentary sequence striking northeast. Thus, an overlap basin model was proposed. Accompanied by opening of the basin, the volcanogenic succession was formed at the block‐faulting stage (131–113 Ma) owing to the closure of the Mongolia–Okhotsk ocean in the Jurassic and early Cretaceous, while the overlying sedimentary sequence was unconformably deposited at the spreading stage (Albian–Maastrichtian) owing to the oblique subduction of the Pacific plate under the Eurasian plate. The volcanic succession constitutes the lower unit of basin filling and is the forerunner of further basin spreading. Copyright © 2002 John Wiley & Sons, Ltd.