青海扎陵湖和鄂陵湖盆地第四纪河湖相地层研究

通过对扎陵湖和鄂陵湖沿岸的湖积阶地中湖相沉积的野外地质调查和实测剖面,对分布于盆地内的第四纪早更新世-全新世湖相地层进行了详细的研究和划分、重新厘定了该区第四纪岩石地层单元,确立了生物地层和年代地层序列.建立了青海东南部地区第四纪早更新世-全新世湖相地层单位-黄河源群(QH),黄河源群是由第四系下更新统野生沟组(Qp~1γ)、中更新统鄂陵湖组(Qp~2e)、上更新统大野马岭组(Qp~3d)和全新统黑河乡组(Qhh)等4个组组成.为青藏高原湖泊演化、气候变化、古地理变迁研究,以及第四纪地层的划分与对比等提供了新资料.     

黄河源区黄河袭夺长江水系之初探

对黄河源区的河流地貌研究表明,该区共发育三级阶地,其中第一、第二级阶地形成于晚更新世的末期至全新世,而第三级阶地形成于晚更新世晚期。在晚更新世晚期,多石峡被切开,黄河源区晚更新世湖泊消失,现今黄河形成。随着现今黄河的形成和晚更新世湖泊的消失,南岸支流之一的多曲向南溯源侵蚀加强,并穿越巴颜喀拉山,夺取了巴颜喀拉山南侧原属于长江流域的贝敏曲和洛曲,使分水岭向南推进了25km,袭夺的时间为晚更新世末期。     

西藏佩枯错盆地第四纪湖相地层的厘定、划分 和佩枯错群的建立

通过对环西藏佩枯错的T1-T16湖积阶地中湖相沉积的野外地质调查和实测剖面,对分布于盆地内的第四纪旱更新世—全新世湖相地层进行了详细的研究和划分,重新厘定了该区旱更新世—全新世的岩石地层单元．确立了生物地层和年代地层序列。首次建立了青藏高原第四纪旱更新世—全新世湖相地层单位——佩枯错群（QP）,佩枯错群由第四系下更新统拉洋组（QP^1l）、中更新统茫家冻组（Qp^2m）、上更新统帮荣组（Qp^3b）和全新统罗马仁布组（Qhl）4个组组成。为青藏高原湖泊演化、气候变化、古地理变迁的研究,以及第四纪地层的划分与对比等提供了新资料。     

汾河裂谷晋中盆地内第四纪沉积序列与沉积环境恢复

晋中盆地是位于汾渭地堑系中部的新生代陆内断陷沉积盆地,研究晋中盆地第四纪的沉积序列对于进一步认识该盆地区域构造和区域气候环境变化具有重要意义。为查明晋中盆地第四纪沉积序列结构、研究揭示晋中盆地第四纪沉积环境及演化,通过构造岩相学方法,对晋中盆地地表和钻孔内第四纪沉积物和沉积环境进行了研究。结果表明:晋中盆地清徐地区地表第四纪沉积序列结构为盆地内部沱阳组河床相和河漫滩相-盆地边缘汾河组河流相—盆山过渡带峙峪组河流相、汾河组冲积扇相及马兰组风积相-基岩山地（盆地外围）二叠系浅海相。钻孔岩芯内第四纪沉积序列结构为下更新统浅湖相和滨湖相—中更新统浅湖相和河流相—上更新统河流相和冲积扇相—全新统冲积扇相。研究认为晋中新生代陆内断陷盆地内沉积序列和演化结构为早更新世陆相湖盆沉积环境—中更新世萎缩湖泊环境—晚更新世强烈萎缩的湖泊和河流环境—全新世再度沉降的陆相湖盆;陆相湖盆从中心向山地沉积环境分带为湖泊沉积环境—河流和湖泊沉积环境—冲积扇沉积环境（盆地边缘出山口区）。盆山过渡带地区上更新世沉积物错位现象与同沉积活动断裂有关,断裂活动性揭示了晋中盆地阶梯式断陷成盆的动力学机制。这些研究成果为区域气候环境变化和晋中盆地区域构造研究提供了新证据,也为太原市城市群建设中工程场址的选择提了供参考。      

青藏高原东北缘若尔盖盆地晚新近纪地层的多重划分与对比

以新构造运动为背景,以岩石地层特征为基础,以多种方法的测年数据为依据,以生物化石种属与产出层位和气候地层为参考,按照多重地层划分观点,本文首次对若尔盖盆地更新统及全新统的生物地层、气候地层和年代地层的划分做了深入研究,进而提出了若尔盖盆地晚新近纪地层的多重划分与对比方案.在以新构造运动为背景下沉积的更新统一全新统生物地层、气候地层等在不同发展阶段具有不同的特征,相同时期不同沉积物之间可以相互对比.利用植物、孢粉和测年数据,"阿坝砾石层"时代划归为早更新世.黄河干流、黑河和白河地层中所产古脊椎动物化石和介形类化石的地质时代为晚更新世.由泥炭孢粉剖面和RM孔孢粉资料揭示出晚冰期到冰后期以来,若尔盖地区的气候表现出极大的不稳定性,冷暖变化频繁,可与由冰期与间冰期或干旱期与湿润期交替演进的气候地层划分的中更新世4366高地冰期和尼格曲一公巴拉克冰期,晚更新世末次冰期早期的木哈隆冰阶、扎尔吉冰阶、羊拱海冰阶、希门错沟冰阶和末次冰期晚期的安纳尔冰阶、全新世冰后期气候地层单位,以及河流堆积阶地划分和风成堆积划分相对应.     

滇池晚更新世末期以来湖积环境分析

通过对滇池湖心区晚更新世末期以来的沉积剖面、沉积物及其化学组合、古地磁特征及孢粉组合的研究,初步确定了滇池上更新统与全新统的分界,认为自晚更新世末期以来,滇池一直维持着稳定的湖相沉积。晚更新世末期,滇池处于温凉偏于的相对浅水环境。全新世早期气候逐渐转暖,湿度渐增,湖水面积扩大且渐深,至全新世中期,气候变得温暖湿润,湖水面积进一步扩大变深。全新世晚期滇池气候又变得温凉偏干、处于湖水面积缩小的浅水环境。     

西藏林芝地区第四系新知

对西藏林芝米林盆地的更新世及其以后的沉积进行了调查研究，磁性地层分析表明这些湖积物的历史不到4万年，在米林的古湖泊沉积物中采获Polypodiaceae等晚更新世孢粉，于米林县白过多更新世湖积之上全新统冲积中新发现林芝智人的头盖骨、牙齿及石斧等，为研究青藏高原第四纪地质作用和古环境、古气候变化及古人类活动等提供了新资料。     

腾格里沙漠西北缘青土湖晚第四纪孢粉组合特征与环境变迁

根据腾格里沙漠西北缘青土湖ZK1孔晚第四纪以来沉积物孢粉组合、磁化率特征和光释光年代的研究,恢复了该区的植被面貌,论述了青土湖地区自中更新世晚期以来的气候变迁特征。研究结果表明,该地区中更新世晚期可划分为凉干和暖湿2个阶段;晚更新世可划分为暖湿和凉干2个阶段,并且与深海氧同位素曲线反映的末次间冰期、末次冰期的次一级气候旋回特征相吻合;全新世该地区主要经历了从暖湿到凉干的气候波动。     

赤峰西部高原第四系沉积环境初探

下更新世本区地壳上升,气候干热。中、晚更新世总计有四次湖水出现,沉积有总厚度150多米的湖积砂;有4次河流出现,遗有50～80余米的冲积砂。每次湖水出现前均以河流作用为主,伴以地壳相对下降或稳定,气候干热。地壳上升气候湿冷。地壳升降,气候变化,河湖交替出现,贯川整个中、晚更新世。全新世地壳上升,湖水萎缩形成许多小湖泊,河谷窄切深大流程短。气候干冷以风作用为主,其南部被风少覆盖是小腾格里沙漠的一部分。     

青海湖的形成与演化趋势

青海湖盆地形成于上新世,湖泊至晚在0.5 Ma前已经形成,在初期有流向贵德盆地的出口。湖泊发育主要划分为三个阶段:中更新世湖泊最盛期、晚更新世湖泊稳定期和全新世湖泊收缩期。晚更新世早期由于湖泊强烈沉陷,使河流出口处相对抬高,河水倒流而形成倒淌河。第四纪以来,我国西北地区有气候逐渐变干的趋势,导致全新世以来青海湖不断收缩。如不采取人工措施,青海湖还将继续收缩。     

鲁北平原晚第四纪地层结构及沉积演化

以54个浅层新钻孔和多个野外露头为研究对象,综合沉积物粒度、薄片、微体古生物、孢粉、14C测年及静力触探等资料,分析了鲁北平原晚第四纪的地层结构和沉积类型,总结了晚更新世晚期以来的沉积演化。研究表明,末次冰期盛冰期到冰后期,受地势、气候条件控制的黄河河道迁移和海水进退是影响地层结构和沉积特征的主要因素,南北地层结构差异明显,发育古河道、湖沼、黄土、三角洲、潮坪和滨浅海等沉积类型,其中古河道分布面积最广,自下而上可划分为三期。晚更新世晚期至早全新世早期,受干冷气候影响,发育第Ⅰ期古河道,小清河以南沉积黄土层;早全新世晚期至中全新世,气候转暖导致海平面升高,沿海地区形成海侵层和三角洲,内陆地区继承性发育第Ⅱ期古河道和湖沼沉积;中全新世末期或晚全新世以来,受黄河泛滥影响,沉积第Ⅲ期古河道和现代黄河三角洲。地层结构和沉积物分布的研究对于分析地下水位的变化规律,以及选择合适的地震激发层等均有重要的指导意义。     

Middle‐Late Pleistocene Glacial Lakes in the Grand Canyon of the Tsangpo River,Tibet

Many moraines formed between Daduka and Chibai in the Tsangpo River valley since Middle Pleistocene. A prominent set of lacustrine and alluvial terraces on the valley margin along both the Tsangpo and Nyang Rivers formed during Quaternary glacial epoch demonstrate lakes were created by damming of the river. Research was conducted on the geological environment, contained sediments, spatial distribution, timing, and formation and destruction of these paleolakes. The lacustrine sediments 14C (10537±268 aBP at Linzhi Brick and Tile Factory, 22510±580 aBP and 13925±204 aBP at Bengga, 21096±1466 aBP at Yusong) and a series of ESR (electron spin resonance) ages at Linzhi town and previous data by other experts, paleolakes persisted for 691~505 kaBP middle Pleistocene ice age, 75–40 kaBP the early stage of last glacier, 27–8 kaBP Last Glacier Maximum (LGM), existence time of lakes gradually shorten represents glacial scale and dam moraine supply potential gradually cut down, paleolakes and dam scale also gradually diminished. This article calculated the average lacustrine sedimentary rate of Gega paleolake in LGM was 12.5 mm/a, demonstrates Mount Namjagbarwa uplifted strongly at the same time, the sedimentary rate of Gega paleolake is more larger than that of enclosed lakes of plateau inland shows the climatic variation of Mount Namjagbarwa is more larger and plateau margin uplifted more quicker than plateau inland. This article analyzed formation and decay cause about the Zelunglung glacier on the west flank of Mount Namjagbarwa got into the Tsangpo River valley and blocked it for tectonic and climatic factors. There is a site of blocking the valley from Gega to Chibai. This article according to moraines and lacustrine sediments yielded paleolakes scale: the lowest lake base altitude 2850 m, the highest lake surface altitude 3585 m, 3240 m and 3180 m, area 2885 km2, 820 km2 and 810 km2, lake maximum depth of 735 m, 390 m and 330 m. We disclose the reason that previous experts discovered there were different age moraines dividing line of altitude 3180 m at the entrance of the Tsangpo Grand Canyon is dammed lake erosive decay under altitude 3180 m moraines in the last glacier era covering moraines in the early ice age of late Pleistocene, top 3180 m in the last glacier moraine remained because ancient dammed lakes didn’t erode it under 3180 m moraines in the early ice age of late Pleistocene exposed. The reason of the top elevation 3585 m moraines in the middle Pleistocene ice age likes that of altitude 3180 m. There were three times dammed lakes by glacier blocking the Tsangpo River during Quaternary glacial period. During other glacial and interglacial period the Zelunglung glacier often extended the valley but moraine supplemental speed of the dam was smaller than that of fluvial erosion and moraine movement, dam quickly disappeared and didn’t form stable lake.     

黄河源地区晚更新世湖泛事件及其意义

通过青海玛多湖相地层剖面沉积特征,结合ESR样品年代测试结果,分析认为黄河源地区在13万年左右的晚更新世时期发生过湖泛事件。湖泛时期,玛多"四姐妹湖"相互连通,形成一个面积巨大的湖泊,约是现今"四姐妹湖"总面积的4.1倍。玛多地区此次湖泛事件与深海氧同位素MIS 6（Marine isotope stages 6）向MIS 5（Marine isotope stages 5）转变时期相对应,显示出青藏高原气候变化与全球气候变化密切相关,然而黄河源地区湖相地层对全球气候变化反应更敏感,记录的气候转换时间早于其他地区。玛多剖面湖相地层剖面沉积物的粒度、碳酸盐、磁化率分析表明,在132±10~128±12 ka年间,黄河源地区湖相沉积可分为9个阶段,表明青藏高原在MIS 6向MIS 5转变时期的气候变化是一个波动上升过程。13万年左右,黄河源地区大面积的湖相地层结束沉积,认为由于青藏高原共和运动,下游的多石峡被切开,湖水突然外泄所形成。      

Late Pleistocene lake and glaciation evolution on the northeastern Qinghai–Tibetan Plateau: a review

Late Pleistocene paleoclimatic history on northeastern Qinghai–Tibetan Plateau (QTP) has been reconstructed mainly from lake sediments; however, data regarding dry–wet climate changes reported in this region are still not clear and controversial. Based on shoreline features and highstand lacustrine sediments around lakes on the QTP, high lake level histories in this paper were summarized and compared with paleoclimatic records from lake sediments, ice core and glaciation evolution surrounding mountains on the NE QTP during late Pleistocene. The results indicate that periods of high lake level occurred at MIS 5, MIS 3 and early-middle Holocene and most likely corresponding to warm and wet climate periods, while periods of low lake level existed in intervening intervals, corresponding to cold and dry climate periods, which most likely coincide with glacial advances surrounding high mountains. With an exception, no wide glacial advance in study area was found during MIS 3, possibly suggesting that effective moisture is lower than that in the other region of NE QTP in this period.     

Geomorphological investigations and luminescence dating in the southern part of the Khangay and the Valley of the Gobi Lakes (Central Mongolia)

Geomorphological investigations in the catchment area of the Baydragiyn river along the southern slope of the Khangay and in the Valley of the Gobi Lakes in western Mongolia provide evidence for Late Quaternary glaciations and lake‐level changes. Thermoluminescence (TL) and infrared optically stimulated luminescence (IRSL) dating of aeolian and colluvial sediments from the central Khangay place the sediments that overlie fluvial and glaciofluvial terraces in the Holocene. An age of 21 ka is determined for a sand deposit overlying the terrace that is related to the last glacial ice‐margin. Lacustrine sediments from higher beach lines in the Valley of the Gobi Lakes provide evidence for a slightly more humid period around 1.5 ka, and a larger extent of the lakes in the Early Holocene at about 8.5 ka, as also reported from other parts of Central Asia. Remnants of lacustrine sediments buried by alluvial gravel, and indicating a huge palaeolake in the basin of the Orog Nuur, however, date to the early stage of the last glaciation around 70 ka. Copyright © 2001 John Wiley & Sons, Ltd.     

东昆仑阿拉克湖地区第四纪水系演化过程及其趋势

根据第四系沉积物的沉积时代、沉积类型及盆山耦合与迁移规律,将东昆仑阿拉克湖地区第四纪水系变迁划分了4个阶段：早更新世小型内陆盆地无序水系阶段;中更新世冰川水系与东流水系阶段;晚更新世柴达木盆地内陆水系向南溯源侵蚀阶段;全新世黄河外泄水系形成与发展阶段。根据研究区及相邻地区黄河水系和柴达木盆地内陆水系的溯源侵蚀发展历史及趋势分析,认为研究区未来水系发展趋势不一定是加鲁河袭夺鄂陵湖、扎陵湖两湖及黄河水系,而可能是黄河加快下蚀作用和溯源侵蚀,鄂陵湖和扎陵湖将逐渐消失成为河流,黄河水系最终将袭夺柴达木内陆盆地水系。     

黄河源地区的河谷地貌特征及其对黄河上游形成和演化的启示

黄河的形成与演化对于认识我国宏观地貌格局的形成、青藏高原及黄土高原的区域构造活动历史、华北平原及黄渤海陆架的形成和演化等问题具有重要意义。目前对黄河演化历史的研究主要集中在龙羊峡以下的河段,对于黄河源段的关注较少。文章基于黄河源地区河谷地貌的实地考察,并利用SRTM1-DEM数据,分析了黄河源段干流及支流河谷橫剖面的地貌特征,并与该区典型的冰川谷和兰州附近黄河的河谷横剖面进行了对比。结果表明:黄河源地区的河谷规模巨大,并呈现出谷底开阔、河床窄小、阶地不明显、谷坡陡立、河谷横剖面左右对称的U型谷特征。这些特征与该区冰蚀谷的特征相似,但与兰州段黄河成型河谷的特征相差甚远,且其河谷规模更大。我们推断,黄河源地区的河谷可能主要为冰期时的冰蚀作用所塑造,而非单纯的流水侵蚀形成。由于冰蚀作用的存在,该区早期的河流阶地可能被随后冰期的冰蚀作用所破坏,当前基于黄河源地区现存河流阶地年代的研究很可能低估了该区水系的发育历史。此外,反复的冰川进退也可能导致黄河源水系自上而下贯通,而非溯源侵蚀形成。     

四川攀枝花昔格达组下伏砾石层成因和时代探讨与古金沙江河谷发育

本文主要描述和讨论了四川省攀枝花市沿金沙江分布、并以炳草岗地龙箐剖面为代表的昔格达组湖相沉积下伏的砾石层的沉积特征及其河流相成因.根据前人对昔格达组湖相沉积的磁性地层学研究结果,为4.2/3.28～2.6/2.12/1.78 MaBP的上新世中、晚期或至早更新世早期,表明其下伏厚达50 m的砾石层的形成时代约为4.2～4.5/5 MaBP的上新世早期.早上新世金沙江河流相砾石层在接近金沙江谷底位置的发现,表明金沙江很早就已经从青藏高原主夷平面下切了2000 m以上、已在接近其现今谷底的位置上存在.这对于探讨古金沙江的河谷发育及其与青藏高原隆升的关系,具有重要的指示意义.     

Micromorphology of Quartz Grain Surface as Indicator of Glacial Sedimentation Conditions: Evidence from the Protva River Basin

Micromorphology of quartz grain surface was studied with the use of scanning electron microscopy in order to specify sedimentation environment in the Protva River Basin in the central Russian Plain. Quartz grains from medium sand fraction (0.25–0.5 mm) taken from 27 samples of Early Pleistocene alluvial sedi-ments and Middle Pleistocene glacial, fluvioglacial, and lacustrine sediments were examined. It was established that the studied sediments contain three major types of quartz grains with (1) glacial, (2) hydrodynamic, and (3) eolian features of transport. Sediments of these genetic types differ by ratios of grains of the micromorphological types. Relationships between eluvial (frost-glacial), hydrodynamic, and eolian components regularly change with variations in climatic conditions. The portion of fluvial component increases in warm conditions, whereas increase of eolian component is typical of cold conditions. The data obtained suggest that the study of morpholithogenesis in glaciation environment should take into consideration not only terrigenous provenances, but also terrigenous agents, i.e., groups of processes responsible for the transport of particles.