Genesis of late pleistocene cross-valley moraine ridges,South—Central Ulster,Northern Ireland

Four genetic varieties of ice-marginal cross-valley moraine ridge have been identified in south-central Ulster, Northern Ireland. Type I ridges are flat topped, composed of stratified, water-lain sediments and formed by coalescence of a series of supraaquatic deltas. Type II ridges are sharp crested, composed of stratified, water-lain sediments and formed by coalescence of a series of subaquatic deltas. Type III ridges show mixed morphological and sedimentological characteristics of type I and II ridges. Type IV ridges are sharp crested or hummocky, composed of poorly-sorted and poorly-stratified water-lain sediments and formed by coalescence of a series of subaquatic sediment gravity flow cones. Field evidence indicates that cross-valley moraine ridges in south-central Ulster were deposited in proglacial lacustrine environments. Ridge type depended principally on (1) the nature of the proglacial bedrock slope; (2) the manner in which meltwater entered the proglacial zone; and (3) ice-sheet behaviour during deglaciation, particularly within the ice-sheet terminus zone.     

Sedimentary Record of the Younger Saalian Ice Margin Stagnation in Eastern Poland: Development of a Regular Pattern of Glaciolacustrine Kames

Glaciolacustrine kames in the Bielsk Podlaski area (eastern Poland) exhibit a unique regular pattern. Three representative morphological kame types were chosen for detailed sedimentological analyses, specifically: isolated, isometric mounds; isolated, elongated hills; and branching ridges. All types comprised fine‐grained sandy and sandy/silty deposits. Lithofacies analysis resulted in the distinction of several lithofacies associations. Associations dominated by medium‐ or large‐scale, massive or horizontally laminated sands are interpreted as proximal subaqueous fans; associations dominated by medium‐ or small‐scale lithofacies of ripple‐drift cross‐laminated sand are interpreted as distal subaqueous fans; and those dominated by sandy/silty, silty or silty/clayey lithofacies with horizontal lamination are interpreted as lake bottomsets. Rates of sediment accumulation appear to have been fast, resulting in syndepositional and metadepositional deformation structures of two types: water‐escape structures, and slumps on subaqueous slopes. After the ice‐walled lake basins filled with sediment, glaciofluvial erosion and deposition alternated, resulting in erosional channels of up to 1 m deep, later filled with gravel or gravely sand. The results indicate that kames developed in a supraglacial environment within a topography of ice‐cored moraines containing ice‐walled lakes that persisted due to the presence of permafrost. Pauses during retreat of the ice walls resulted in ice‐contact deformations at the edges of the kames. Kame formation is therefore consistent with a continental climate and this may explain the increased abundance of this type of kame system in Eastern Europe.     

藏东南地区冰碛物斜坡钢花管注浆加固试验研究

本文以藏东南地区帕隆藏布流域冰碛物斜坡为例,针对其架空结构较多、固结程度欠佳的特点,提出钢花管注浆加固技术。通过15个注浆孔现场注浆、现场开挖、取样测试等,探讨其施工工艺及加固效果,并结合FLAC3D数值模拟,进一步阐明其加固机理及设计方法。研究结果表明,冰碛物浅表层注浆有效加固半径为20~55 cm,浆液扩展路径与架空结构展布息息相关;注浆加固后土体粘聚力、内摩擦角、压缩模量均得到改善,竖直渗透系数变小;其注浆压力宜采用0.5~1.0 MPa;水灰比宜选用2、1;注浆孔间距与有效加固半径的比值不宜大于8。通过现场试验,形成一套基于3.5 m³空压机、YT28型凿岩机、空心自钻式锚杆及气动式注浆机的花管注浆工艺,轻便快捷,施工效率高,尤其适用于交通不便、施工条件差的情形。     

祁连山第四纪冰碛物的ESR测年研究

论述了ＥＳＲ测年的原理和方法,并利用ＥＳＲ测年方法对祁连山的冷龙岭和走廊南山的摆浪河流域第四纪冰碛物进行了年代测定,结果表明,冰碛物样品的ＥＳＲ年龄与野外地层对比推测的年龄和和＾１４Ｃ、ＴＬ测定的年龄基本一致,且同一冰碛物不同位位置采集的样品年龄也一致,说明本次测定的冰碛物年龄是可信及可靠的。     

Outburst mechanism of Yindapu Glacial Lake in Tibet

At present, the mechanism research on glacial lake outburst mainly focuses on the ice quake and ice landslide, etc. To some glacial lakes, the seepage deformation is the dominant factor in outburst process. Taking the Yindapu Glacial Lake in Tibet as an example, using SEEP/W module of FEM software (GEO-STUDIO), the authors analyzed seepage stability of terminal moraine ridge dam. The leading role of seepage deformation in some glacial lake outburst mechanism is proposed and proved.     

川藏公路然乌-鲁朗段冰碛高边坡稳定性分析

在帕隆藏布北岸的川藏公路上,有许多冰碛高陡切坡.这些冰碛切坡具有独特的结构力学特征,其几何形态(高度与坡度的组合值)不同于一般经验值的范围.根据其物理力学性质,采用圆弧法对边坡进行稳定性分析,取得了与实际相符的结果.     

波堆藏布谷地冰碛丘陵形成机制及其环境意义

波堆藏布谷地中分布着大面积的冰碛丘陵, 通过考察发现其个体大小、外形、分布规模及内部砾石组成等方面都与高纬大冰盖外围形成的冰碛丘陵有很大的区别. 以冰川沉积学理论为基础, 从沉积动力学的角度讨论中低纬度波堆藏布谷地中冰碛丘陵的形成机制. 结果表明: 气候变化造成冰川的大面积死冰加之宽阔的河谷、海洋性冰川的特性促使波堆藏布谷中形成如此大面积的冰碛丘陵; 同时,大规模的冰碛丘陵表明气候转暖(抑或变干)的过程是突变的.     

大连红黏土形成期研究

从大连红黏土被第四系松散层所覆盖的现象出发,分析了大连地区沿海岸附近冰碛残丘的特征与形成过程。论证了大连地区陆地和海湾的红黏土都具有聚合沉积的特征,并且确定了大连红黏土形成期是在第四系冰川期之前。此外论证了大连红黏土是大连地区古地理古气候的标志性地层之一。