长白山现代理论雪线和古雪线高度   总被引：9，自引：2，他引：7       下载免费PDF全文

张威  闫玲  崔之久  穆克华  李川川  牛云博 《第四纪研究》2008,28(4):739-745

根据冰川地貌和地形特征、岩性、冰川沉积物的风化程度以及OSL测年结果,认为长白山地区发育两期冰川作用,即末次冰盛期和晚冰期,测年结果分别为20.0±2.1ka和11.3±1.2ka。根据平衡线（ELA）处6～8月多年平均气温（T）和年降水量（P）的关系,计算长白山现代理论雪线高度为3380±100m。通过积累区面积比率AAR（accumulation-arearatio）、冰川末端到山顶高度TSAM（the terminal to summit altitudinal）,冰川末端至分水岭平均高度Hofer（the terminal to average elevation of the catchment area）、末端至冰斗后壁比率THAR（toe-to headwall altitude ratios）、冰斗底部高程CF（cirque-floor altitudes method）、侧碛堤最大高度法MELM（maximum elevation of lateral moraines）等方法计算该区末次冰盛期雪线高度为2250～2383m,平均值2320±20m。考虑到末次冰盛期后地壳上升20m,当时雪线的实际高度为2300±20m,冰盛期的雪线降低值为10⁸0±100m。晚冰期北坡和西坡的雪线高度分别为2490m和2440m,平均值2465m,考虑新构造运动后的雪线实际高度2454m,降低值926±100m。长白山新构造运动（LGM上升约20m,晚冰期上升约11m）在末次冰盛期以来对冰川发育的影响不明显。  相似文献   

西藏札达盆地上新统一早更新统河湖相地层多重地层划分与对比   总被引：1，自引：1，他引：0  

朱大岗  孟宪刚  邵兆刚  杨朝斌  王津  韩建恩  余佳  孟庆伟  吕荣平 《地球学报》2008,29(2):137-144

根据札达盆地河湖相地层实测剖面中的接触关系、沉积旋回、沉积体系、岩相、岩性、古生物特征和ESR、古地磁测年结果,笔者对札达盆地上新统一早更新统河湖相地层进行了重新划分和时代确定。结合该套河湖相沉积的岩石地层、生物地层、年代地层、磁性地层、层序地层和地质构造事件,对札达盆地上新统一早更新统河湖相地层进行了多重地层的划分与对比。将札达盆地河湖相地层划分为3个组、4个沉积相、7个沉积亚相、11个岩性段。由新到老划分为：早更新统香孜组（Qp^1-1X）、上新统古格组（N22g）和上新统托林组（N2^1t）。  相似文献   

Lake George revisited: new evidence for the origin and evolution of a large closed lake,Southern Tablelands,NSW, Australia. 2: earliest Pleistocene (Gelasian) environments     

M. Macphail  L. K. Fifield  B. Pillans  G. Hope 《Australian Journal of Earth Sciences》2016,63(4):453-468

The three sedimentary units infilling Lake George provide the longest quasi-continuous sedimentary record of any Australian lake basin. A combination of cosmogenic nuclide burial, magnetostratigraphy and biostratigraphic dating techniques previously has shown that the basal (fluvial) unit, the Gearys Gap Formation, began accumulating at ca 4 Ma, in the early Pliocene (Zanclean), and (ii) deposition had ceased by ca 3 Ma, in the mid-late Pliocene (Piacenzian). The same techniques confirm the middle unit, the (fluvio-lacustrine) Ondyong Point Formation began accumulating in the late Pliocene and deposition continued into the earliest Pleistocene (Gelasian) when a shallow but probably laterally extensive freshwater lake extended across the drillhole site. Our data provide a minimum Gelasian age for tectonic blockage of former spillway(s) and formation of paleo-Lake George. Whether this was the earliest lake to form within the basin is unknown, since the dated intervals are separated by a ferric hardpan, interpreted as representing a prolonged period of erosion or non-deposition. Temperate rainforest angiosperms including Nothofagus growing during the late Pliocene had been extirpated or become extinct during this interval, although a number of gymnosperms, now endemic to New Caledonia, New Guinea, New Zealand and Tasmania still survived in the otherwise sclerophyll-dominated vegetation. The succession of plant communities is considered to be due to effectively drier local conditions, which in turn reflect regional aridification during the Plio-Pleistocene transition, despite the formation of a freshwater lake across the basin. The sequence provides a reliable framework for recognising and correlating Plio-Pleistocene deposits elsewhere on the Southern Highlands.  相似文献   

山东广饶地区晚更新世以来沉积演化与古气候变迁     

杨剑萍  庞效林  王海峰  贾军涛  刘玲 《沉积学报》2016,34(1):79-89

受晚更新世以来海侵影响,渤海西南内陆第四系浅层经历了复杂的海陆交替演化。利用4口钻孔取芯井和88口静力触探井资料,采用现代测试技术和地层对比的方法对渤海西南内陆广饶地区第四系浅层进行沉积学综合研究。广饶地区地表以下30 m内,南部以风成黄土沉积为主,北部自上而下发育两期海相层,在研究区称为第一、第二海侵层,分别是10~4 ka B.P.的黄骅海侵层和40~28 ka B.P.的献县海侵层。黄土沉积于晚更新世玉木冰期,在研究区南部以17 m为界划分为大站组和羊栏河组(未见底)。晚更新世以来发生两期海侵事件(黄骅海侵、献县海侵),在海侵范围最大时到达广饶地区,先后对冰期沉积黄土层侵蚀改造,形成了“上超型海蚀黄土”的海侵演化模式。根据海侵与黄土沉积演化所对应的古气候变迁,将研究区晚更新世以来气候演变划分为6个期次:干冷期、温暖湿润期、干冷偏凉期、温暖期、潮湿湿润期和现代气候期,对应不同的沉积演化特征。  相似文献   

渤海湾西南部平原DC01孔晚更新世以来的地质环境变化     

李建芬  王福  陈永胜  方晶  商志文  田立柱  施佩歆  姜兴钰  王宏 《地质通报》2016,35(10):1590-1599

通过对渤海湾西南部平原DC01孔的岩石地层学、生物地层学及年代地层学和地球化学研究,重建了该地区自晚更新世以来的地质环境演化过程。全新世之前,研究区经历了由河流-盐沼-潮间带上部/低盐沼-河口湾-泻湖-淡化泻湖的环境转化过程;进入全新世之后,该区经历了由湖沼到河流的环境转化过程。埋深22.4~12.7m发育近10m厚的弱海相沉积,AMS~(14)C年龄表明,该层沉积形成时间早于4.35ka cal BP,可能属于MIS 3早期(6.0~5.5ka cal BP)或更早的MIS 5期(12~8ka cal BP)。恢复了该时期的相对古海面,最高可达-13.31m。DC01孔缺失MIS 4~2或MIS 2时期的沉积。  相似文献   

Evolution of the Galicia Interior Basin over the last 60 ka: sedimentary processes and palaeoceanographic implications          下载免费PDF全文

Anxo Mena  Guillermo Francés  Marta Pérez‐Arlucea  Till J. J. Hanebuth  Vera B. Bender  Miguel A. Nombela 《第四纪科学杂志》2018,33(5):536-549

The Galicia Interior Basin (GIB; NW Iberian Peninsula) is located near a critical transition between the subtropical (temperate) and subpolar (cold) gyres of the North Atlantic. It therefore witnesses oceanographic changes driven by global climatic events. This study reports on the recent (latest Pleistocene) sedimentary, palaeoceanographic and palaeoclimatic history of the basin. We integrated analysis of deep‐sea sediment cores retrieved from an E–W transect across the GIB. The analysis indicated three types of sedimentary processes recording glacial (Marine Isotope Stage 2–4) and deglacial events: along‐slope bottom currents (forming contourite deposits), pelagic and hemipelagic sedimentation, and gravitational dislocation. Variation in depositional patterns and sedimentation rates indicate distinctive transport (along‐slope and down‐slope) and depositional processes. These in turn reflect climatic and oceanographic drivers. We interpret changes in sea level from core evidence showing changes in sediment supply. The cores exhibited conspicuous sedimentary evidence of Heinrich events (HEs). The stratigraphic intervals associated with HEs showed significant lateral variation. We suggest that the lateral variation may result from the development of an oceanographic boundary between surface water masses with different temperature and salinity parameters or changes in surface currents which may have introduced relatively warmer water into the GIB during the last glacial period.  相似文献   

苏北盆地早、中更新世地球化学元素变化特征与青藏高原隆升响应     

苗巧银  姜丽  黄顺生 《江苏地质》2018,42(2):206-215

青藏高原隆升的研究多集中在高原内部及周边,对其他地域的研究鲜有报道。苏北盆地ZKJ30、ZKJ32、ZKJ43等钻孔样品的微量元素Be、Ga、Cr和常量元素Fe及氧化物Al_2O_3、MgO、Fe_2O_3、TiO_2、Na_2O、CaO、P_2O_5等在早、中更新世不同深度段呈现较明显的含量拐点变化,含量逐渐增加且存在旋回性等变化特征,反映早、中更新世气候与沉积环境发生了根本性的变化,进而响应于青藏高原早、中更新世阶段性隆升。由于印度板块和欧亚板块碰撞的内在动力,青藏高原隆升的同时苏北盆地拗陷并沉积成平原,这种大范围的西部造山、东部成盆现象,符合盆山耦合关系,推知苏北平原及高邮凹陷的形成均与青藏高原的隆升存在一定的响应及因果关系。  相似文献   

Evolution of a Late Pleistocene palaeolake in Dali Nor area of southeastern Inner Mongolia Plateau,China     

Yuanhong Lan  Mingzhong Tian  Xujiao Zhang  Xuefeng Wen  Chunjing Kang 《地学前缘(英文版)》2018,9(1):223-237

Lithological,geochronological,granulometric,and scanning electron microscope(SEM)analyses of eight lacustrine outcrops indicate the existence of a large palaeolake in Dali Nor area during 149-24.6 ka(MIS5-3)and a small one in upstream of the Xilamulun River during 12.96-11.69 ka.The large palaeolake recorded its highest water level above 1300 m during the MIS3 and covered the whole Dali Nor basin and upstream of the Xilamulun River within an area of about 3000 km~2.However,the small palaeolake with a highest water level above 1200 m,covered an area of about 600 km~2.Besides the reconstruction of palaeolake areas,this study also looked into the evolutionary process of the palaeolake during the Late Pleistocene.Our data provide insights on the timing of appearance of the large palaeolakes and a better understanding of the mechanism responsible for variations in the environment conditions of dry lands in middle latitudes.  相似文献   

Proglacial damlakes in eastern Transbaikalia: New insight into the Pleistocene paleogeography     

F.I. Enikeev 《Russian Geology and Geophysics》2018,59(9):1109-1119

Paleogeographic reconstructions for the Samarovo, Taz, Murukta, and Sartan glaciations reveal the formation conditions of proglacial lakes dammed by ice in intermontane depressions and valleys of large rivers in eastern Transbaikalia. Middle-Late Pleistocene climate change is reconstructed using spore-pollen spectra from Pleistocene sediments in northern Transbaikalia. The age and lifetime of proglacial lakes are constrained by radiocarbon, thermoluminescence, and varve chronology of their bottom sediments in the periglacial zone. The lake levels remain recorded in sediments produced by deposition and erosion along the former lake shores, as well as in morphology and lithology variations of terminal moraines. A large proglacial lake, with a maximum level of 1020 m, occupied vast areas in Transbaikalia and its surroundings during the Samarovo glaciation. After the glaciers degraded, the Amur River system expanded into the area of closed lake basins in the southeastern Baikal region, including North China and Mongolia. The obtained results have implications for the Middle-Late Pleistocene history of lake deposition.  相似文献   

Environments of the climatic optimum of MIS 11 in Britain: evidence from the tufa sequence at Hitchin,southeast England     

J. E. Sherriff  D. C. Schreve  I. Candy  A. P. Palmer  T. S. White 《第四纪科学杂志》2021,36(4):508-525

Marine Oxygen Isotope Stage 11 (MIS 11, Hoxnian Interglacial) is an important interval for understanding both climate change in an interglacial partially analogous to the Holocene and the response of geomorphic processes, biotic systems, and hominin populations to these changes. In Britain, many sites correlated to MIS 11 have not been studied since the mid-20th century and require reinvestigation, including the Hitchin tufa sequence, where a rich, non-marine molluscan assemblage was originally recovered. Re-excavation of the Hitchin tufa sequence for this study was focussed on combined sedimentological, micromorphological and geochemical analyses of the deposits. These indicate that tufa formation occurred within a perched springline system under temperate climatic conditions. Shifts between paludal and fluvial tufa facies within this system occur concomitantly with changes in carbonate geochemistry, representing increased humidity caused by a change in rainfall amount or seasonality. This research enables a correlation of the sequence to the climatic optimum of MIS 11c, the main warm phase of MIS 11, and permits further insights into temperature and hydrological changes in this interval by generating the first geochemical records of hydroclimatic evolution during the MIS 11 thermal maximum in Britain.  相似文献