Discovery of eclogite and its geological significance in Qiangtang area, central Tibet

Eclogites have been found in the margin of the Qinghai-Tibet Plateau respectively since the 1990s. First Eocene eclogite from Himalayan belt was discov- ered in Kaghan valley, northern Pakistan in 1991, in which coesite was identified[1,2]. Then two eclog…     

论草地建设在黄土高原地区生态环境建设中的战略地位

我国黄土高原地区当前植被稀疏,生态环境恶劣,由于人类历史时期这一地区之天然植被中草原占有较大面积,所遭受的人为活动的破坏也最为显著;加上经多年实践,一批适生草类在黄土高原地区生态环境变得十分严酷的山塬丘陵与风沙滩地比造林易于成活,改善生态环境与造林立地条件之功用易于见效,在经济上也易于获得回报,因而在这一地区实施绿色屏障方略、再造秀美山川之生态环境建设系统工程中,人工种草实处于奠基础的重要战略地位,应通过采取加强宣传教育、制订工作规划、认真管理、加强科学技术研究与指导等措施,大规模推行实施。     

Age dating of lacustrine sediments in Lake Tianshuihai of the Tibetan Plateau by using U-series isochron method and its significance

The age of the clastic-clay sediments with varied content of carbonate in core TS95 taken from the Lake Tianshuihai in the northwest of the Tibetan Plateau was determined successfully by using the total sample dissolution U-series isochron method for the first time. With this method, the serial absolute timescale (isotope time scale) covered the last 240 ka in the main body of the Tibetan Plateau with a sea level up to 4000 m is also established for the first time, thereby laying the foundation for the research on the paleoclimate and palaeoenvironment in the Lake Tianshuihai region as well as the relationship between evolution of the Tibetan Plateau and global changes. In addition to a brief introduction of the basic principles, the procedures of experiments, and the results, this note also presents the adaptability and superiority of this method as well as its possible problems.     

Magnetostratigraphy and pavleo-environmental record of Tertiary deposits of Lanzhou Basin

The Tertiary deposits of the Yongdeng section, the Lanzhou Basin were studied by means of magnetostrati-graphy. The magnetostratigraphic sequences from Paleocene to Miocene were established, and the time scale for the corresponding stratigraphy and mammalian faunas was also established by referring to their correlation to the GPTS of BKSA95 (The geomagnetic polarity time scale which was thoroughly revised and updated by Berggreen et al. in 1995). In the end the paleoenvironmental records and their relationship with the uplifting of the Tibetan Plateau were discussed. The results are as follows. The top boundary of the Xiliugou Formation is dated to be 51 Ma, i.e. Eocene. TheYehucheng Formation covers the time span of 51-31.5 Ma, i.e. from late Early Eocene to early Early Oligocene. The Xianshuihe Formation covers the time span of 31.5-15 Ma, i.e. from Early Oligocene to Middle Miocene. The lower member of the Xianshuihe Formation spans from 31.5 to 20.0 Ma, i.e. from Early Oligocene to early Early Miocene. The middle member is from 20.0 to 16.5 Ma, i.e. in the middle Early Miocene.     

Magnetostratigraphy of Late Tertiary sediments from the Chinese Loess Plateau and its paleoclimatic significance

The Late Tertiary red clay/bed sediments underlying the Quaternary loess-paleosol in the Chinese Loess Plateau possesses high-resolution paleoclimatic changes related to the uplift of the Tibetan Plateau. Magnetostratigra-phy and susceptibility measurements are discussed in this paper. The paleomagnetic results show that the red clay/bed began to accumulate at about 8.1 Ma, which represents the oldest Late Tertiary deposit continuously in the central Loess Plateau. The magnetic susceptibility curves show stepwise increases since the initiation of red clay, superimposed on several peaks. Moreover, the magnetic susceptibility increased abruptly since 3.8 Ma, which probably indicates the inception of the modern East Asia monsoon system. Between 3.8 and 2.6 Ma, the stepwise increases of susceptibility may imply progressively intensified East Asia summer monsoon activity related with the stepwise uplift process of the Tibetan Plateau.     

西藏札达盆地构造与沉积特征

札达盆地位于青藏高原南西部,是发育于喜马拉雅山内部的盆地。盆地北东侧以阿依拉日居断裂为边界,该断裂属逆冲性质。西北边界为曲松断裂,为一拆离断层。盆地西南主边界为藏南拆离系（STDS）,是盆地主控构造。盆地内部沉积了巨厚的第三纪地层,可以分为上下2个部分,即上部的湖相沉积和下部的河湖交互相沉积。湖相沉积是以泥岩为主的巨厚沉积;河湖交互相沉积以砾岩层的出现为标志,可分为3个沉积旋回。札达盆地的主控构造为伸展构造,但同时经受了垂直于造山带的挤压作用。     

长爪沙鼠1～5号染色体G显带特征初步研究

目的　通过易于区分的 1～ 5号长爪沙鼠染色体G显带特性研究 ,逐步建立完整的长爪沙鼠G带染色体细胞遗传学背景资料。方法　取 6只成熟长爪沙鼠 ,雌雄各半 ,采用外周血进行淋巴细胞培养 ,获得分裂中期细胞染色体标本制片 ,以胰蛋白酶处理 ,选 1周龄标本染色观察。结果　长爪沙鼠染色体指数表明 ,1～ 5号染色体以相对长度、着丝点位置易于排列。 1号染色体与 2号染色体各有八条深染带纹 ,可以着丝点位置加以区分。 3号染色体有六条深染带纹 ,位于着丝点附近和长臂与短臂中部无穷侧端。 4号染色体与 5号染邑体均有四条深染带 ,5号染色体短臂深染带纹位于着丝点一侧可予以区分。结论　长爪沙鼠 1～ 5号染色体有较稳定的基本深染G带型 ,可做为染色体区带划分的重要标界。     

青藏高原地面加热场与春季川渝地区气温的关系

应用奇异值分解(SVD)技术,研究了青藏高原地面加热场与东亚地区上空500hPa高度场及其东侧川渝地区春季气温场的时空联系和冷暖异常成因.结果表明:前期冬季青藏高原地面加热场与后期春季高度场的第1模态代表了两场间的主要耦合特征,具有显著的时空相关;前期冬季青藏高原地面加热场通过影响后期春季500hPa高度场,导致未来春季大气环流变化,是造成川渝地区春季气温异常的重要原因.       

新构造运动与四川盆地构造演化及气藏形成

新构造运动控制中国东部新生代裂谷含油气盆地形成 ,丰产油气资源。改造了上扬子地台区及青藏高原古生界—中生界油气藏形成的地质构造条件。大量油气层受到破坏。青藏高原隆升构成中国新构造运动的中心 ,它控制了四川盆地新生代断褶构造演化及海相碳酸盐岩气藏形成。构造发育程度控制气藏形成及分布。发育程度高的背斜 ,原有油气藏遭到破坏 ;发育程度中—低及隐伏背斜 ,富集天然气成藏。四川盆地气藏形成及保存的地层构造条件 ,可作为上扬子地台区及青藏高原找油气指南     

基于词汇的蒙古语文语转换的实验

蒙古语是一种很有影响的语言,较放西有许多独特的方面,本介绍了一个基于词汇的蒙古语语转换系统的设计与实现。