Late Quaternary sea‐level change and evolution of Belfast Lough,Northern Ireland: new offshore evidence and implications for sea‐level reconstruction     

Ruth M. K. Plets  S. Louise Callard  J. Andrew G. Cooper  Joseph T. Kelley  Daniel F. Belknap  Robin J. Edwards  Antony J. Long  Rory J. Quinn  Derek W. T. Jackson 《第四纪科学杂志》2019,34(4-5):285-298

The interplay of eustatic and isostatic factors causes complex relative sea‐level (RSL) histories, particularly in paraglacial settings. In this context the past record of RSL is important in understanding ice‐sheet history, earth rheology and resulting glacio‐isostatic adjustment. Field data to develop sea‐level reconstructions are often limited to shallow depths and uncertainty exists as to the veracity of modelled sea‐level curves. We use seismic stratigraphy, 39 vibrocores and 26 radiocarbon dates to investigate the deglacial history of Belfast Lough, Northern Ireland, and reconstruct past RSL. A typical sequence of till, glacimarine and Holocene sediments is preserved. Two sea‐level lowstands (both max. ?40 m) are recorded at c. 13.5 and 11.5k cal a bp . Each is followed by a rapid transgression and subsequent periods of RSL stability. The first transgression coincides temporally with a late stage of Meltwater Pulse 1a and the RSL stability occurred between c. 13.0 and c. 12.2k cal a bp (Younger Dryas). The second still/slowstand occurred between c. 10.3 and c. 11.5k cal a bp . Our data provide constraints on the direction and timing of RSL change during deglaciation. Application of the Depth of Closure concept adds an error term to sea‐level reconstructions based on seismic stratigraphic reconstructions.  相似文献   

晚第四纪MIS6以来柴达木盆地成盐作用对冰期气候的响应   总被引：2，自引：0，他引：2  

陈安东  郑绵平  宋高  王学锋  李洪普  韩光  袁文虎 《地质论评》2020,66(3):611-624

气候是控制柴达木盆地盐类沉积的主要因素之一,但是其作用机制尚待明确。作者以柴达木盆地察汗斯拉图盐湖的3个含盐剖面为研究对象,采用多接收电感耦合等离子质谱(MC-ICP-MS)铀系测年测定其沉积时代,并通过X射线粉晶衍射(XRD)分析测定其盐类矿物种类。铀系测年显示D18剖面石盐和芒硝层的沉积时代为13.1±2.0 ka BP～15.9±2.5 ka BP,其中芒硝沉积年代属于末次冰期MIS2晚期;MXK2剖面芒硝层的沉积时代分别为131.7±39.5 ka BP和158.3±10.8 ka BP,D12剖面芒硝层的沉积时代分别为166.6±20.2 ka BP和198.0±20.6 ka BP,可以对应于倒数第二次冰期MIS6。XRD分析确定了3个剖面的盐类矿物主要为芒硝、石盐和石膏。综合多个盐湖晚第四纪成盐数据,本文认为倒数第二次冰期MIS6和末次冰期MIS2是柴达木盆地晚第四纪重要的成盐期,冰期的冷干气候有利于石盐和芒硝等盐类沉积。柴达木盆地"冰期成盐"的根本原因,是由于冰期环境下盆地周边山体冰川规模的扩张以及干冷的冰期气候,共同造成了盐湖补给水量的减少。此外,晚第四纪MIS6和MIS2的冰期降温也是导致盆地中冷相盐类沉积的直接原因。  相似文献   

1990—2018年中巴经济走廊冰湖时空变化特征     

姚超  王欣  赵轩茹  魏俊锋  张勇 《冰川冻土》2020,42(1):33-42

中巴经济走廊是贯通南北丝路的关键枢纽。在全球变暖的背景下， 区域内冰川变化情况复杂， 部分冰川出现前进或跃动现象， 冰湖溃决的风险在不断上升， 进而威胁中巴经济走廊的建设与民生安全。基于1990—2018年Landsat TM/ETM+/OLI遥感影像， 利用目视解译方法提取了中巴经济走廊3期冰湖编目数据， 并分析了28年来该区域内冰湖的总体变化趋势、 空间异质性以及成因。结果表明： 中巴经济走廊目前共发育有2 380个冰湖， 总面积为（131.76±19.08） km²， 集中分布于喀喇昆仑山脉和喜马拉雅山脉； 1990—2018年期间， 冰湖总体面积扩张速度为0.48%·a^-1， 但各个山脉不同规模冰湖面积变化差异较大。中巴经济走廊在气温和降水的共同作用下， 区内冰湖面积呈扩张趋势， 同时气温和降水变化率的空间差异使得冰湖面积变化存在空间差异； 冰川的快速退缩增加了区内冰湖溃决的风险。  相似文献   

Provenance of sediment in the Labrador Current: a record of hinterland glaciation over the past 125 ka          下载免费PDF全文

LONGJIANG MAO  DAVID J. W. PIPER  FRANCKY SAINT‐ANGE  JOHN T. ANDREWS  MARKUS KIENAST 《第四纪科学杂志》2014,29(7):650-660

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Suspended sediment and total dissolved solid yield patterns at the headwaters of Urumqi River,northwestern China: a comparison between glacial and non‐glacial catchments          下载免费PDF全文

Wenhua Gao  Shu Gao  Zhongqin Li  X. X. Lu  Mingjun Zhang  Shengjie Wang 《水文研究》2014,28(19):5034-5047

In order to understand the differences in the suspended sediment and total dissolved solid (TDS) yield patterns between the glacial and non‐glacial catchments at the headwaters of Urumqi River, northwestern China, water samples were collected from a glacier catchment and an empty cirque catchment within the region, during three melting seasons from 2006 to 2008. These samples were analyzed to estimate suspended sediment and TDS concentrations, fluxes and erosion rates in the two adjoining catchments. There were remarked differences in suspended sediment and TDS yield patterns between the two catchments. Suspended sediment concentrations were controlled mainly by the sediment source, whereas TDS concentrations were primarily related to the hydrologic interaction with soil minerals. Generally, the glacial catchment had much higher suspended sediment and TDS yields, together with higher denudation rates, than the non‐glacial catchment. Overall, glacial catchment was mainly dominated by physical denudation process, whereas the non‐glacial catchment was jointly influenced by physical and chemical denudation processes. The observed differences in material delivery patterns were mainly controlled by the runoff source and the glacial processes. The melting periods of glacier and snow were typically the most important time for the suspended sediment and TDS yields. Meanwhile, episodic precipitation events could generate disproportionately large yields. Subglacial hydrology dynamics, glaciers pluck and grind processes could affect erodibility, and the large quantities of dust stored on the glacier surface provided additional sources for suspended sediment transport in the glacial catchment. These mechanisms imply that, in response to climate change, the catchment behaviour will be modified significantly in this region, in terms of material flux. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Character and origin of De Geer moraines in the Seacoast region of New Hampshire,USA          下载免费PDF全文

Samantha N. Sinclair  Joseph M. Licciardi  Seth W. Campbell  Brian M. Madore 《第四纪科学杂志》2018,33(2):225-237

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Luminescence dating reveals a rapid response to climate change of fluvial terrace formation along the Ani River,northeastern Japan,during the last glacial period     

《Quaternary Geochronology》2022

Fluvial terraces along the middle reaches of many Japanese rivers were formed during the last glacial period as a result of changes in sediment discharge related to cooler temperatures and/or reduced water discharge because of lower precipitation. The influence of climate change on these fluvial terraces is not yet fully understood because most previous studies lacked detailed reconstructions of the chronology of terrace development. This study provides a detailed luminescence chronology of fluvial terrace deposits along the Ani River, northeastern Honshu, Japan, and compares that chronology to paleoclimatic records. Eight samples for luminescence dating were obtained from an outcrop of terrace deposits (∼10 m thick) in the Ani River valley. The fading-corrected infrared stimulated luminescence (IRSL) ages are consistent with the fading-corrected post-IR IRSL ages for some samples, which suggests that fading corrections were effective despite the higher fading rates of the IRSL signal. However, for the other samples, the post-IR IRSL ages are significantly older than the fading-corrected IRSL ages due to incomplete bleaching. The pulsed IRSL signals are close to field saturation for older samples, which might have resulted in a greater variation of the ages. Fading-corrected IRSL ages demonstrate periods of rapid aggradation during 105–90 ka and 75–60 ka. Comparison of terrace development with paleoclimatic records indicates that the two periods of fluvial deposition correspond to decreases in precipitation caused by weakened East Asian summer monsoon precipitation and possibly decreases in temperature. The results of this study show that the Ani River responded rapidly to climate change on a time scale of a few tens of thousands of years during the last glacial period.  相似文献   

2000—2020年兴都库什东部冰川区物质平衡变化及其影响因素     

骆建伟  柯长青  喻薛凝 《冰川冻土》2022,44(1):159-170

利用SRTM DEM和ASTER立体像对数据获取的DEM分析了2000—2020年兴都库什东部的冰川物质平衡,并结合CRU TS 4.04气象数据探讨了气温、降水、地形和冰湖对南、北冰川区物质平衡空间差异的影响。结果表明：2000—2020年兴都库什东部冰川区物质平衡为（-0.02±0.04） m w.e.·a^-1,冰川整体呈现微弱的负物质平衡状态。从坡向来看,南坡以正物质平衡冰川居多,北坡以负物质平衡冰川居多。从南、北两个子区域来看,北部冰川区物质平衡为（0.07±0.04） m w.e.·a^-1,南部冰川区物质平衡为（-0.32±0.04） m w.e.·a^-1。北部冰川面积规模大,所处海拔区间高,南部则相反。北部冰川区处于较高的海拔区间且冬季气温较低,导致夏季升温所产生的冰川消融的影响被削弱,冰川物质平衡的分布与降水分布在空间上具有一致性。南部冰川区出现的强烈物质亏损主要是由于夏季气温的急剧升高和冰川处于较低的海拔区间。南、北区域冰前湖和冰面湖面积不断扩大的空间差异性,也在一定程度上加剧了该地区冰川物质平衡的空间差异。  相似文献   

山地冰川演化与冰湖发育相互作用机制北大核心CSCD     

王琼  王欣  雷东钰  殷永胜  魏俊锋  张勇 《冰川冻土》2022,44(3):1041-1052

冰川-冰湖耦合过程是冰冻圈物质与能量循环的重要组成部分,系统刻画冰川演化与冰湖发育过程的相互作用机制,对于完善冰冻圈科学理论体系和认知冰川作用区变化规律、水循环模式和灾害效应具有重要意义。本文立足山地冰川演化和冰湖发育过程,系统归纳了冰川-冰湖相互作用研究进展,剖析了冰川作用与冰湖发育耦合机制及相关模型的应用,并对现有冰川演化与冰湖发育过程耦合机制研究存在的不足与挑战进行解析和总结。冰川-冰湖耦合过程的深入研究有助于提高数值模拟的可信度与精度,为评估冰川-冰湖耦合过程影响、建立灾害监测预警体系和采取适应性措施提供数据与理论基础。  相似文献   

基于Hkr值的北天山冰川侵蚀空间分布特征及其主控因素研究     

姚盼  王杰  林文旺  曾兰华  陈仁容 《冰川冻土》2022,44(4):1260-1269

确定冰川侵蚀的主控因素及其与各影响因素间的相互作用方式,不仅对深入认识冰川侵蚀的物理机制和理解冰川作用区地貌演化具有重要的意义,也是探讨构造、气候、地形间相互关系的根本。然而,以往的学者仅在构造活动略单一的区域研究冰川侵蚀的主控因素,致使对构造的影响认识不足,那么,构造是否是冰川侵蚀的主控因素呢？又是如何作用于冰川侵蚀？北天山第四纪冰川作用规模巨大,留下了丰富的冰川遗迹,其气候与构造条件也多样,因而成为探讨上述问题的理想区域。本文在北天山北坡自西向东选取了7个冰川流域,基于每个流域的Hkr值和冰川侵蚀影响因子的定性定量数据,分析了该区域冰川侵蚀的分布规律及其影响因素。结果表明,北天山各流域冰川侵蚀自西向东有减小趋势,该变化趋势是构造、气候、地形共同作用所致。其中,山顶高度和降水对冰川侵蚀的影响最显著,两者均通过对冰川规模施加作用来控制冰川侵蚀,而构造也可能通过影响顶点高程、积累区面积、冰川规模,进而作用于冰川侵蚀,但是其是否发挥主要作用有待进一步认识。因此,冰川规模可能才是导致北天山各冰川流域侵蚀差异的根本原因。  相似文献