若尔盖高原及其周围山地的冻土和环境

若尔盖高原内部年平均气温０．６～３．３℃，气温年较差１９．１～２１．２℃，已不具备多年冻土形成和保存的气候条件。据１９９２年７月间试坑和钻孔测温，在１．０～２．２ｍ深处地温为５～８．４℃，浅层地下水温６．０～７．８℃，由此判断不存在多年冻土，季节冻结深度为１．０～２．０ｍ。据冻土现象和试坑资料判断，周围山地海拔４１５０～４２００ｍ以上发育山地岛状多年冻土。区内沼泽演化表明，部分沼泽已疏干或向疏干趋势发展，草场退化和草原沙化已成为本区生态环境的重要问题，并已影响畜牧业发展     

RILL EROSION PROCESS ON STEEP SLOPE LAND OF THE LOESS PLATEAU

IntheLoessPlateau,alongtheslopelengthfromthetoptothebottom,soilerosionischaracterizedbyobviousverticalzonaldivision,thatis,sheeterosionzone,sheeterosionandrillerosionzone,rillerosionandshallowgullyerosionzoneandgullyerosionzone.Inthesheetandrillero..sionzone,rillerosionamounttakesup70%ofthetotalsoilloss[TANGKenetal.,1983,ZHENGFenlietal.,19871;intherillandshallowgullyerosionzone,rillerosionamountaccountsfor30--40%ofthetotalsoilloss.Sorillerosionisamajorerosionpatternonsteepslopeland.Riller…     

Environmental evolution of Zoigê Basin since 900 kaB.P. and comparison study with Loess Plateau

The Zoige Basin is located in the eastern margin of the Qinghai-Xizang Plateau, in which two cores, RH and RM, have been drilled, with the depths of 120 m and 310 m respectively. The former with the bottom age of 826 kaB. P. has been divided into 21 stages according to the multi-proxy analysis, which could be basically compared with the oxygen isotope record of deep-sea core. The palaeoclimatic and palaeoenvironmental process of the Zoigê Basin over the past 900 kaB. P. is reconstructed, and the comparison of core RH with the Luochuan Loess record is made.     

Magnetostratigraphy and palaeoclimate of Red Clay sequences from Chinese Loess Plateau

Two Red Clay profiles near Xi’an and Xifeng were investigated in an attempt to determine magnetostratigraphic and palaeoclimatic records. The results show that aeolian dust accumulation and the related East Asia palaeomonsoon system had begun by 6.5 Ma, and it is deduced that the Tibetan Plateau had reached a significant elevation at that time. The late Tertiary palaeoclimatic history of the Red Clay as reflected by magnetic susceptibility is reconstructed during the period of 6.5–2.5 Ma. Stepwise increase in susceptibility of aeolian dust accumulation appears to have a close correlation to the uplift processes of the Tibetan Plateau. The remarkable increase of aeolian dust accumulation at 3.2 Ma appears to be due to the influence of global ice volume on the East Asia monsoon. Palaeomonsoon variation during the late Tertiary as recorded in the Red Clay sequences from the Chinese Loess Plateau can be regarded as the product of a number of interacting factors, such as uplift of the Tibetan Plateau, solar radiation, global ice volume, etc. Project supported by the National Natural Science Foundation of China and the Foundation of Xi’an Laboratory of Loess and Quaternary Geology, Chinese Academy of Sciences.     

青藏高原东北缘及其邻区的地壳结构与地震关系初探

用人工地震测深资料及天然地震反演结果给出了东经９６°～１０８°，北纬３２°～４０°范围内的莫霍面埋深图，并讨论了莫霍面轮廓与中强地震发生的关系。结果表明，中强地震多发生在地壳厚度急剧变化、陡变带拐弯处及中地壳顶部存在低速层的区域内     

由震源机制和地震波各向异性探讨青藏高原岩石圈变形

本文据青藏高原天然地震震源参数和地震波各向异性资料，讨论了高原岩圈不同圈层的变形特性。     

中国南方海相含油气保存单元的层次划分与综合评价

以最近十年中国南方的海相新区油气勘探评价成果为依托 ,以油气成藏和整体封闭保存体系评价为核心 ,在渝东—湘鄂西、中下扬子和滇黔桂三大区域划分出 9个有利区块 5 1个含油气保存单元 ,并将其归纳为四个层次。综合评价认为 ,方西和石柱保存单元具有较好的整体封存体系 ,属持续性含油气保存单元 ,为首选勘探目标 ;江汉盆地南部、句容—海安区块、南鄱阳坳陷、楚雄盆地东北部具备或基本具备整体封存条件 ,属于沉积重建型含油气保存单元 ,通过精细勘探可望获得商业性油气流 ;楚雄盆地西北部、南盘江坳陷、十万大山盆地和渝东—湘鄂西地区利川复向斜由于晚期强烈构造改造而仅存在部分封存体系 ,需要攻关探索 ;思茅、渝东—湘鄂西地区的花果坪和桑植—石门地区已失去整体封闭保存条件 ,仅局部存在封存体系 ,地质条件高度复杂 ,勘探风险甚高。     

Study of charge structure and radiation characteristic of intracloud discharge in thunderstorms of Qinghai-Tibet Plateau

The comprehensive observations on lightning discharges were conducted in Naqu area of Qinghai-Tibet Plateau in summer of 2002. The electric structures of thunderstorms and the characteristics of lightning discharges at initial stage were analyzed by using the observation data. The results show that most of intracloud (IC) lightning flashes were polarities inverted in thunderstorms with tripole electric charge structure and occurred between negative charge region located in the middle of the thunderstorm and positive charge region located at the bottom of the thunderstorm. The radiation characteristics of discharge processes in cloud with longer lasting time involved in Cloud-to-Ground (CG) lightning flashes were similar to that of IC discharges.A lot of radiation pulses were produced in these discharge processes. Because the IC discharges took place at the bottom of thundercloud and were near the ground, they may produce more serious damage to equipment on the ground therefore should not be neglected in lightning protection.     

The Rotational Structure along the Eastern Segment of the Altyn Tagh Fault and Its Implications in Dynamics

As a result of the left-lateral strike-slipping of the Altyn Tagh fault in Neotectonic period, a contra-rotational structure, namely the Zhaobishan vortex structure, has developed at the juncture of the main Altyn Tagh fault and the northern fringe fault of the Qilian Mountains.Preliminary analysis on the deformation and evolution of the Zhaobishan vortex structure. In combination with the previous data, suggests that the tectonic transform between the Altyn Tagh fault and the northern fringe fault of the Qilian Mountains attributes to the deformation of the rotational structure. The existence of a series of rotational structures along the Altyn Tagh fault and on the northeastern edge of the Qinghai-Xizang(Tibet) plateau indicate that as the substance in the northern Qinghal-Xizang (Tibet) plateau moves clockwise around the eastern tectonic knot of the Himalayas, rotational structures become the principal mode on the northern marginal zone of the Plateau of transforming and absorbing tectonic deformation.     

天山山区近40a年降水变化特征与南、北疆的比较

本文分析了天山山区近40 a来年降水变化的基本特征，并与南疆、北疆进行了比较，所得的主要结果如下：(1)天山山区在年降水量干湿变化阶段上与北疆的相似性强于南疆。(2)年降水量的空间分布的同步变化性以北疆为最好，南疆最差，天山山区居中，而年降水量的空间分布的反向变化性，以天山山区为最大，北疆最小，南疆居中。(3)天山山区与南疆从60年代到90年代，年降水均表现出了持续的增加的趋势，北疆年降水从60年代到90年代，除70年代外，不断增多。