Left-lateral shear deformation found in southern part of the Gaoligong range in west Yunnan and its tectonic implications

LocatedinthesouthwestborderareaofChina ,theGaoligongrangeisauniquegeologicandgeomor phologicfeature ,withitssnow cappedsummitele vatedupto 35 88mabovesealevel.ItgoesupnorthalongtheNuRivertoeasternTibet ,joiningupwiththeBoshulalingrange ,anddownsouthtotheareaofLongling ,whereitdescendsrapidlyandsplitsupintoseverallowandlinearridges .RespectivelytothewestandeastoftherangearetheTengchongandBaoshanblocks ,themainpartofwhich ,anarrowbeltofin tensivelydeformedmetamorphicrocksnamedGaoligongGroup …     

~(40)Ar/~(39)Ar age evidence for Altyn fault tectonic activities in western China

As the northern boundary of the Tibetan Plateau theAltyn fault is a huge NEE strike-slip fault belt in the inner Asian continent. Its formation and evolution are closelyrelated to the uplift of the whole plateau and the mass es-cape to the east. In recent years the Altyn fault has be-come a hot point of geological study in the Tibetan Pla-teau. The formation age of the Altyn fault was argued for a long time. Some researchers emphasized that the Altyn fault had commenced since early Paleo…     

Tectonic evolution of Tethyan tectonic field, formation of Northern Margin basin and explorative perspective of natural gas in Tarim Basin

 Analyzing the characteristics of the Tethyantectonic field, the authors think that the Tethyan tectonicfield underwent three evolutional stages: closing of Pa-leo-Tethys and rifting of Neo-Tethys from early Permian tolate Triassic, subduction of Neo-Tethys and collision betweenthe Indian plate and the Eurasia plate from Jurassic to earlyof low Tertiary, and collision between the Arab plate and theEurasia plate and the A-type subduction of Indian plate fromlate of low Tertiary to the present. Combining the evolutionof the Tethyan orogenic belt with the characteristics of theNorthern Margin basin, it is suggested that the sedimentaryand tectonic characteristics and types of the Northern Mar-gin basin are controlled by the formation and evolution ofthe Tethyan orogenic belt and the ingression of Tethys. Theevolution of Northern Margin basin can be divided into threedevelopment stages: back-arc foreland basin from late Per-mian to Triassic, the back-arc fault subsidence and depres-sion from Jurassic to the early of low Tertiary, and the reac-tive foreland basin from the late of low Tertiary to the pre-sent. The Northern Margin basin in the Tethyan tectonicfield is an important region for natural gas accumulation,and the Tarim Basin is a part of this region.     

Rapid assessment and explanation of tree species abundance along the elevation gradient in Gaoligong Mountains,Yunnan, China

This article presents an analysis of tree species abundance and its association with climatic variables along elevation gradient in the Gaoligong Mountains in west Yunnan, China. Data from scientific papers and books in the Gaoligong Mountains area were collected and extrapolated to elucidate a mechanistic understanding of elevation patterns and the relationship between the elevation range and elevation mid-point of tree species along the gradient by examining climatic variables. Tree species abundance showed a unimodal pattern with a peak at mid-elevation (about 2000 m) and species with a narrow elevation range occurred at higher or lower elevation, while a wider elevation range was found at the middle of the gradient. Tree species abundance was the highest where both temperature and water availability were moderate. The relationship between the climatic variables affecting species appear to be due to both direct and indirect factors, and the effect of these effects varied at different gradients.

     

减阻流中聚合物的流体动力学行为研究

基于单参数的椭球－珠簧二元模型，分析了减阻流中聚合物分子的动力学行为，求解数值积分运动方程后，得到了聚合物分子的周期运动规律和剪切稀化现象．研究结果表明，由于聚合物分子的变形效应，其旋转频率随着剪切率的增大而减小，从而提高了流体的稳定性．该模型为减阻机理的研究提供了动力学分析基础．     

Two new carnivores from an unusual late Tertiary forest biota in eastern North America

Late Cenozoic terrestrial fossil records of North America are biased by a predominance of mid-latitude deposits, mostly in the western half of the continent. Consequently, the biological history of eastern North America, including the eastern deciduous forest, remains largely hidden. Unfortunately, vertebrate fossil sites from this vast region are rare, and few pertain to the critically important late Tertiary period, during which intensified global climatic changes took place. Moreover, strong phylogenetic affinities between the flora of eastern North America and eastern Asia clearly demonstrate formerly contiguous connections, but disparity among shared genera (eastern Asia-eastern North America disjunction) implies significant periods of separation since at least the Miocene epoch. Lacustrine sediments deposited within a former sinkhole in the southern Appalachian Mountains provide a rare example of a late Miocene to early Pliocene terrestrial biota from a forested ecosystem. Here we show that the vertebrate remains contained within this deposit represent a unique combination of North American and Eurasian taxa. A new genus and species of the red (lesser) panda (Pristinailurus bristoli), the earliest and most primitive so far known, was recovered. Also among the fauna are a new species of Eurasian badger (Arctomeles dimolodontus) and the largest concentration of fossil tapirs ever recorded. Cladistical analyses of the two new carnivores strongly suggest immigration events that were earlier than and distinct from previous records, and that the close faunal affinities between eastern North America and eastern Asia in the late Tertiary period are consistent with the contemporaneous botanical record.     

安徽桐城挂车河镇地区东西向韧性剪切带分形特征及其估算应变速率适用性分析

 安徽桐城挂车河镇(挂镇)地区东西向韧性剪切带包括早期长英质韧性主剪切带、晚期镁铁质韧-脆性剪切带和伴生的长英质同向或牵引变形带.两期长英质构造岩中石英动态重结晶新颗粒发育,边界具有锯齿状或港湾状等不同的微观特征,具有统计意义上的自相似性和明显的分形特征.其分形维数介于1.097~1.144,变形温度介于600~700℃,变形条件相当于麻粒岩相和同构造花岗岩;高温流变学方法估算应变速率低于10^-7.27s^-1,镁铁质韧-脆性剪切带伴生初糜棱岩的应变速率比主韧性剪切带糜棱岩的小0.5数量级左右.分形维数可用作变形温度计和应变速率计,但石英颗粒变形实验推导的Kruhl温度计和Takahashi应变速率计在天然变形岩石中应用很少.与其他方法估算的变形温度和应变速率综合对比结果表明,Kruhl温度计是适用的,而Takahashi应变速率计仅适用于低温(T<400℃)条件.     

下扬子地区盆地的"四层楼"结构及其动力学机制

下扬子地区震旦纪以来经历了不同的大地构造与地球动力学背景 ,盆地演化相应地经历了震旦纪—中三叠世海盆→晚三叠世—中侏罗世沿江前陆盆地→晚侏罗世—早白垩世火山岩盆地→晚白垩世—早第三纪陆相伸展盆地。下扬子地区震旦纪—中三叠世海盆发育于伸展性被动大陆边缘。沿江前陆盆地形成于扬子与华北板块碰撞活动中的前陆变形带上。火山岩盆地出现于区域性走滑剪切和环太平洋岩浆弧背景下。库拉—太平洋板块高角度、高速正面向东亚大陆下的俯冲 ,造成了岩石圈上拱拉张 ,从而产生了晚白垩世—早第三纪的陆相伸展盆地。随着西太平洋边缘弧后盆地的出现及印度与欧亚板块的碰撞 ,中国东部遭受近东西向挤压 ,从而结束了下扬子地区的盆地演化历史。     

岩石单结构面剪切变形渗透性演化规律

为了研究剪切作用下单裂隙渗透性的演化规律,在Comsol中采用Weierstrass随机分形函数来生成单裂隙,调整2个裂隙面的相对位移来模拟剪切作用,通过分析不同剪切位移条件下裂隙隙宽的变化以及不同流量下的非线性效应发生的界定范围,并绘制散点图与函数曲线拟合确定剪切过程影响裂隙渗透率的因素,给出定量关系。结果表明：未发生剪切时,隙宽的概率密度分布满足标准的高斯分布,而随着剪切过程的发生,隙宽的高斯分布被破坏,仅体现标准高斯分布的部分特征;发生剪切时,渗透率先有一个减小的过程,然后在一定范围内波动;当Re>9.6时,流体开始从线性向非线性发展。对岩石单结构面剪切变形过程中裂隙孔径变化对流体渗流特性的影响进行模拟,可为分析地质体中结构面变形对地热变化的影响提供参考。     

反压护道在贵惠高速公路软土地基处理中的应用

本文在现场监测分析的基础上,结合地基变形特征的模拟,研究原地基、反压后的地基和固结后的反压地基的变形与稳定性变化情况,重点比较三种状态地基的竖向沉降、横向位移、剪应力、剪应变、孔隙水压力的变形程度。研究结果表明:相对于原路基来说,反压后的路基使原路基的坡脚产生较大的竖向沉降,并产生指向路基中点的水平位移,而且最大剪应力、最大剪应变及孔隙水压力都有所减少。相对于反压后的路基来说,固结后的反压路基使地基在面层范围内有了较大的竖向沉降,并产生指向路基中点的水平位移,而且最大剪应力、最大剪应变及孔隙水压力都有所减少。文章最后综合实测的沉降量与数值模拟,对路基最终的工后沉降做出了预测。     

基于抗变形能力的级配碎石组成设计方法

级配碎石的主要缺陷是易产生较大的塑性变形。在分析现行级配组成设计方法的基础上,根据连续密级配碎石的加州承载比(CBR)试验和利用研制的柔性材料剪切性能测试仪进行的剪切性能试验结果,对基于抗变形能力的级配碎石组成设计方法进行了研究。结果表明:以CBR值和剪切强度为组成设计的性能控制参数,CBR值应不小于180%,剪切强度应大于0.52 MPa;以最大粒径、泰波(Taibol)级配指数n值和基于双指标控制的关键筛孔及其通过率合理变化范围作为级配控制参数,最大粒径宜为31.5 mm,要求不高时可以放宽到37.5 mm;n值控制在0.45~0.50之间,以0.50为宜;4.75、2.36、0.60、0.075 mm筛孔应作为关键筛孔予以控制;通过率应在基于双指标控制的合理变化范围内。由此提出了基于抗变形能力的级配碎石组成设计方法,通过试验路应用表明,该设计方法可以有效控制级配碎石的塑性变形。     

沥青混合料同轴剪切强度试验方法研究

根据沥青路面混合料受力特点,讨论了同轴剪切强度试验的合理性.通过有限元计算,结合同轴剪切强度试验的破坏特征,确定了同轴剪切强度试验中最大剪应力的出现位置.定义1kN单位荷载作用下试件内最大剪应力为剪切强度系数,在普通温度(15～60℃)条件下,剪切强度系数基本不受温度和混合料模量变化的影响,且确定剪切强度系数值为0.140MPa.kN-1.车辙试验结果表明,沥青混合料同轴剪切强度与沥青混合料高温永久变形具有较好的相关性.     

红河断裂与金沙江断裂的GPS监测研究

采用中国地壳运动观测网络的观测数据,计算出了红河断裂两侧、金沙江断裂两侧所选测站在欧亚参考框架下的水平运动速度;用最小二乘法求得红河断裂的运动速率为2.02mm/a,运动方向为南偏东76°,表明红河断裂现今活动性较小,把红河断裂的运动速度分解在红河断裂的走向和倾向上,推出红河断裂的性质为右旋走滑,且有一定的拉张特征;用最小二乘法求得金沙江断裂的运动速率为2.49 mm/a,运动方向为正东,表明金沙江断裂现今活动性较小,把金沙江断裂的运动速度分解在金沙江断裂的走向和倾向上,推出金沙江断裂几乎没有走滑,但有一定的拉张特征。     

高黎贡山南段种子植物区系科属的两种不同排序方法及其意义

高黎贡山南段迄今计有种子植物192科,887属,2 807种。将其科属按所含种的绝对数目和区系存在度两种不同排序,以提供完整的高黎贡山南段种子植物区系的区系组成,反映本区系的独特特点和各科属在区系建成中的相对重要性。     

西藏措勤—赛利普地区新生代火山岩地球化学特征

青藏高原拉萨地块是印度板块与欧亚板块碰撞的重要地区之一,其中广泛发育的碰撞—后碰撞岩浆岩记录了新生代以来印度大陆岩石圈向北俯冲的全过程以及拉萨地块在碰撞-后碰撞之后的岩浆作用类型.基于对措勘—赛利普地区新生代火山岩地球化学及Sr、Nd同位素资料的分析,表明火山岩中以明显富碱和高钾为特征;Sr同位素呈递增而Nd同位素呈递...     

框筒结构的简化分析模型

将楼层整体变形分为剪切变形和弯曲变形,用壁式框架D值法和等效连续体法,对在侧向荷载作用下框筒结构进行简化分析.在考虑翼缘框架对剪切变形影响的前提下,应用壁式框架D值法对整体剪切变形进行分析;在考虑剪力滞效应的前提下,用等效连续体法推导剪力滞系数,分析整体弯曲变形.算例结果表明,简化计算与空间框架计算的结果接近,各柱轴向应变的误差在2%～8%之间,水平位移误差在10%之内.     

基于数字照相的砂土剪切变形模式的试验研究

利用自行研制的数字照相量测软件包Photolnfor和自行设计的大型剪切试验装置，在不同围压下，对砂土的剪切变形模式以及土体变形局部化的发生、发展和演变过程进行了全面观测．结果表明：砂土变形区域呈纺锤型，由多条曲线形大变形带和带间小变形区组成，不同围压下的剪切变形模式基本相近；土体最终形成的剪切带与初期发生的局部变形带并不完全重合；土体剪切变形可分为初期全域快速弹性变形、中期局部区域塑性变形与后期剪切带内集中塑性变形三个阶段．     

高分子共混物分散相的剪切形变与仿射形变

研究了简单剪切流场中两相共混物分散相的剪切形变，得出了分散相形变及取向角与剪切应变的关系式，与仿射形变对分散相形变的预测相比，剪切形变的预测值与实验值相符得较好，它从流体力学角度揭示了分散相层状分布的机理，在大应变的情况下，仿射形变和剪切形变和剪切形变对分散相形变度的预测趋于一致，在大应变和小应变的情况下，分散相取向角的剪切形变预测值与Ｔａｙｌｏｒ和Ｃｏｘ理论相符。     

塔北喀拉玉尔滚断裂系构造特征及地质意义

喀拉玉尔滚断裂系位于塔里木盆地北部,是塔北系列北西向展布的断裂之一。为了研究喀拉玉尔滚断裂系性质以及对塔北构造格局的影响,通过野外考察以及地震剖面解释,得出喀拉玉尔滚断裂为一条北西向右旋走滑断裂,受挤压-剪切作用,伴生北喀、中喀和南喀3个雁列褶皱以及次级断裂,为典型走滑断裂展布形态。喀拉玉尔滚断裂带由古生界北西向构造带继承演化而来,曾经历古生代强烈挤压构造运动、中生代平静沉积、新生代斜冲运动3期构造作用,形成了现今地表构造样式。喀拉玉尔滚断裂带处在乌什-温宿构造单元和库车-塔北构造单元之间,对两侧变形、差异压缩起到调节作用。喀拉玉尔滚走滑断裂及其伴生构造的发育可能对油气的运移和聚集产生有利条件。