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1.
A chronostratigraphy based on luminescence data was established at a key loess profile (Duttendorf) in the northern alpine foreland of Austria. The data help to constrain the timing and duration of the Last Glacial Maximum (LGM) in the area of one of the largest east Alpine piedmont glaciers, the Salzach palaeoglacier. Climate deterioration and maximum advance of this glacier were coeval with the beginning of the main loess accumulation phase in the glacier forefield at ～29–30 ka. A late LGM‐outwash gravel layer deposited on top of the loess profile marks the end of the LGM glacier activity at ～20 ka. The geomorphological setting around the loess profile provides evidence of a major glacier oscillation during the course of the LGM, a phenomenon qualitatively known from other alpine palaeoglaciers but never interpreted in terms of palaeoclimate. A LGM glacier oscillation similar to that of the Salzach palaeoglacier was reported recently from the south Alpine Tagliamento palaeoglacier, suggesting a common forcing. The onset of loess deposition at Duttendorf and the tentatively contemporal advance of the Salzach palaeoglacier reflect, as do other data, the drastic cooling in Europe as a result of Heinrich event 3. The first glacier maximum is not well constrained in the study area but a correlation with the better dated Tagliamento amphitheatre suggests a possible response to Heinrich 2. The second re‐advance occurred synchronously (within dating uncertainties) in both palaeoglaciers forefields (at ～21 ka) but the forcing mechanism remains unknown. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
2.
天山乌鲁木齐河源末次冰期冰川沉积光释光测年 总被引：6，自引：5，他引：1
乌鲁木齐河源地区是中国冰川遗迹保存最丰富、地貌最典型的区域之一,是根据冰川遗迹重建第四纪冰川历史的理想地区。大量的研究工作以及技术测年结果也使其成为试验冰川沉积光释光（optically stimulated luminescence,OSL）测年可行性的理想地点。共采集了6个冰碛及上覆黄土样品用于光释光测年。提取38~63 μm的石英颗粒,运用SAR-SGC法测试等效剂量。各种检验表明测试程序是适用的。通过地貌地层关系、重复样品、已有年代的对比等方法,检验该地冰川沉积OSL测年的可行性。结果表明,OSL年代结果与地貌地层新老关系非常吻合,与已有的其他测年技术的年代结果也具可比性,表明这些样品的OSL信号在沉积之前晒退较好,OSL年代是可信的。冰川观测站侧碛垄的OSL年代为14.8±1.2 ka;9号冰川支谷口附近冰碛的OSL年代为13.5±1.1 ka和17.2±1.3 ka;上望峰冰碛的OSL年代为20.1±1.6 ka。综合OSL年代结果与此前其他测年结果,这几套冰碛垄形成于深海氧同位素MIS 2阶段应该是比较统一的认识。上望峰冰碛上覆黄土的OSL年代（10.5±0.8 ka）也印证了该结论。OSL年代指示上望峰冰碛对应于末次冰期最盛期,冰川观测站和9号冰川支谷谷口冰碛对应于晚冰期。下望峰冰碛的OSL年代为36.3±2.8 ka,对应于MIS 3阶段。下望峰冰碛的形成时代,仍有待更多沉积学以及测年工作进一步确定。 相似文献
3.
文章回顾了1965年李四光先生追寻末次冰期对环境影响的讲话,以及40余年来在天津-河北沿海钻孔地层中、末次盛冰期下切河谷的发现过程。在源到汇过程中,起码自晚更新世以来,研究区已经是古黄河沉积区,多处发现的末次盛冰期下切河谷底板多位于30~32 m深度,低于全新统底板一般在20 m的深度;与长江口地区钻孔末次盛冰期下切河谷深62 m相比,研究区下切河谷规模不如前者,也没有一个统一的大河口。末次盛冰期下切河谷最远地点,是距现代海岸约80 km的河北省孟村回族自治县县城北侧,即西汉黄河亚三角洲叶瓣顶部。众多钻孔见早全新世快速沉积,只能是黄河支流有这样充足的泥沙供给,在局部顶托了早全新世海侵作用发生。 相似文献
4.
Michael J. Bentley 《Quaternary Science Reviews》1999,18(14):211
The volume of Antarctic ice at the Last Glacial Maximum is a key factor for calculating the past contribution of melting ice sheets to Late Pleistocene global sea level change. At present, there are large uncertainties in our knowledge of the extent and thickness of the formerly expanded Antarctic ice sheets, and in the timing of their release as meltwater into the world’s oceans. This paper reviews the four main approaches to determining former Antarctic ice volume, namely glacial geology, glacio-isostatic studies, glaciological modelling, and ice core analysis and attempts to reconcile these to give a ‘best estimate’ for ice volume. In the Ross Sea there was a major expansion of grounded ice at the Last Glacial Maximum, accounting for 2.3–3.2 m of global sea level. At some time in the Weddell Sea a large grounded ice sheet corresponding to c. 2.7 m of global sea level extended to the shelf break. However, this ice expansion has not yet been confidently dated and may not relate to the Last Glacial Maximum. Around East Antarctica there was thickening and advance offshore of ice in coastal regions. Ice core evidence suggests that the interior of East Antarctica was either close to its present elevation or thinner during the last glacial so the effect of East Antarctica on sea level depends on the net balance between marginal thickening and interior thinning. Suggested East Antarctic contributions vary from a 3–5.5 m lowering to a 0.64 m rise in global sea level. The Antarctic Peninsula ice sheet thickened and extended offshore at the Last Glacial Maximum, with a sea level equivalent contribution of c. 1.7 m. Thus, the Antarctic ice sheets accounted for between 6.1 and 13.1 m of global sea level fall at the Last Glacial Maximum. This is substantially less than has been suggested by most previous studies but the maximum figure matches well with one modelling estimate. The timing of Antarctic deglaciation is not well known. In the Ross Sea, terrestrial evidence suggests deglaciation may have begun at c. 13,000 yr BP1 but that grounded ice persisted until c. 6,500 yr BP. Marine evidence suggests the western Ross Sea was deglaciated by c. 11,500 yr BP. Deglaciation of the Weddell Sea is poorly constrained. Grounded ice in the northern Antarctic Peninsula had retreated by c. 13,000 yr BP, and further south deglaciation occurred sometime prior to c. 6,000 yr BP. Many parts of coastal East Antarctica apparently escaped glaciation at the LGM, but in those areas that were ice-covered deglaciation was underway by 10,000 yr BP. With existing data, the timing of deglaciation shows no firm relation to northern hemisphere-driven sea level rise. This is probably due partly to lack of Antarctic dating evidence but also to the combined influence of several forcing mechanisms acting during deglaciation. 相似文献
5.
《第四纪科学杂志》2017,32(1):48-62
6.
IAN M. HOWAT EUGENE W. DOMACK 《Boreas: An International Journal of Quaternary Research》2003,32(1):56-75
This study analyses acoustic profiles of two mid-shelf troughs, the JOIDES Basin and Pennell Trough in the western Ross Sea, Antarctica. These troughs are subglacial erosion features formed by repeated advance of streaming ice onto the Ross Sea continental shelf. Sediment wedge formations, interpreted to have been deposited at the most seaward grounding zone during the Last Glacial Maximum (LGM), are observed within the mid-shelf region of these troughs. By correlating high-resolution acoustic profiles with core samples, we resolve the stratigraphy of these wedge formations to assess the relationships between bathymetry, subglacial sediment distribution and palaeo-ice-stream configuration. The grounding zone wedge geometries were controlled by the pre-existing topography. The JOIDES and Pennell Troughs were only partially infilled during the LGM. Axial diamict progradation from the landward margin of the troughs indicates enhanced flow (debris supply) along the axis of ice flow. Differences in grounding zone geometries indicate a decrease in basal debris deposition and/or supply during ice recession. The lack of a recessional ice-shelf facies indicates that either the ice shelf was absent during retreat, or that there was no melt-out of basal debris. 相似文献
7.
Geomorphic evidence of former glaciation in the high Drakensberg of southern Africa has proven controversial, with conflicting glacial and non‐glacial interpretations suggested for many landforms. This paper presents new geomorphological, sedimentological and micromorphological data, and glacier mass‐balance modelling for a site in the Leqooa Valley, eastern Lesotho, preserving what are considered to be moraines of a former niche glacier that existed during the Last Glacial Maximum (LGM). The geomorphology and macro‐sedimentology of the deposits display characteristics of both active and passive transport by glacial processes. However, micromorphological analyses indicate a more complex history of glacial deposition and subsequent reworking by mass movement processes. The application of a glacier reconstruction technique to determine whether this site could have supported a glacier indicates a reconstructed glacier equilibrium line altitude (ELA) of 3136 m a.s.l. and palaeoglacier mass balance characteristics comparable with modern analogues, reflecting viable, if marginal glaciation. Radiocarbon dates obtained from organic sediment within the moraines indicate that these are of LGM age. The reconstructed palaeoclimatic conditions during the LGM suggest that snow accumulation in the Drakensberg was significantly higher than considered by other studies, and has substantial relevance for tuning regional climate models for southern Africa during the last glacial cycle. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
8.
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
9.
Ramn Pellitero Jos M. Fernndez‐Fernndez Nstor Campos Enrique Serrano Alfonso Pisabarro 《第四纪科学杂志》2019,34(4-5):342-354
New 10Be dates for glacial landforms in the Fuentes Carrionas area (Cantabrian Mountains, nothern Spain) are presented. Mapped and dated landforms in Fuentes Carrionas made possible a palaeoglacier reconstruction for four glacial stages. Results were compared to other nearby palaeoenvironmental proxies, so a final approximation on the mean annual temperature and annual precipitation that caused the four glacial advance stages is proposed. Glaciers reached their maximum extension at 36 ka, in a cold and dry environment. A second advance stage took place between 18.5 and 19.5 ka, during the Last Glacial Maximum (LGM), when glaciers advanced in a wet environment, with positive rainfall anomalies. A third glacial advance was dated during the Oldest Dryas, in which climate shifted to extremely cold and dry conditions. Finally, a last stage has been identified and proposed to the Younger Dryas, in which precipitation anomalies are negligible. Our results confirm some of the previously made palaeoglacial and palaeoenvironmental inferences for the Iberian Peninsula, as well as provide valuable and accurate anomalies, which are useful for climate modelling. 相似文献
10.
《Quaternary Science Reviews》2007,26(9-10):1197-1203
Reconstructions of the British–Irish Ice Sheet (BIIS) during the Last Glacial Maximum (LGM) in the Celtic Sea and southern Ireland have been hampered by a paucity of well-dated stratigraphic records. As a result, the timing of the last advance of the largest outlet of the BIIS, the Irish Sea Ice Stream, to its maximum limit in the Celtic Sea has been variously proposed as being pre-last glaciation, Early Devensian and LGM. The Irish Sea Till was deposited by the Irish Sea Ice Stream during its last advance into the Celtic Sea. We present 26, stratigraphically well constrained, new AMS radiocarbon dates on glacially transported marine shells from the Irish Sea Till in southern Ireland, which constrain the maximum age of this advance. The youngest of these dates indicate that the BIIS advanced to its overall maximum limit in the Celtic Sea after 26,000–20,000 14C yr BP, thus during the last glaciation. The most extensive phase of BIIS growth therefore appears to have occurred during the LGM, at least along the Celtic Sea and Irish margins. These data further demonstrate that the uppermost inland glacial tills, from the area of supposed “older drift” in southern Ireland, a region previously regarded as having been unglaciated during the LGM also date from the last glaciation. Thus most of southern Ireland was ice covered at the LGM. Advance of the BIIS to its maximum southern limit in the Celtic Sea may have been a short-lived glaciodynamic response facilitated by subglacial bed conditions, rather than a steady-state response to climate forcing alone. 相似文献
11.
Glacial deposits are present at the head of the Ürümqi River valley, Tianshan, Central Asia. 10Be surface exposure ages of 15 boulders from three sites along a 12 km valley transect range from 9 to 21 ka suggesting emplacement by glacial retreat and advance commencing at the global last glacial maximum (LGM) and most likely abating in the early Holocene. Although the age spread for a given locality is not small, perhaps indicating post-depositional reworking, maximum ages per site are either coeval with or are post-LGM and inconsistent with previous pre-LGM electron spin resonance ages. 相似文献
12.
Darama Yakup Selek Zeliha Selek Bulent Akgul Mehmet Ali Dagdeviren Murat 《Natural Hazards》2019,97(1):211-227
Natural Hazards - Hasanlar Dam and Hydroelectric Power Plant are located on Küçük Melen Creek in the Western Black Sea Basin of Turkey. The dam was constructed in 1974 to provide... 相似文献
13.
14.
Glacial landforms and sediments provide evidence for the existence of two Late Pleistocene major glacial advances in the Queer Shan, northern Hengduan Mountains in the eastern Tibetan Plateau. In the current study, optically stimulated luminescence and electron spin resonance dating results reveal that the two glacial advances occurred during Marine Isotope Stage (MIS) 3 and the Last Glacial Maximum (LGM) in MIS 2, respectively. Geomorphic evidence shows that the glacial advance during MIS 3 was more extensive than that in MIS 2. This glacial advance is synchronous with other glaciated areas in the Himalaya and Tibet, but contrasts with global ice volumes that reached their maximum extent during the LGM. Glaciers in the Queer Shan are of the summer accumulation type and are mainly fed by precipitation from the south Asian monsoon. Palaeoclimate proxies show that during MIS 3 the south Asian monsoon strengthened and extended further north into the Tibetan Plateau to supply more precipitation as snow at high altitudes. This in turn led to positive glacier mass balances and caused glaciers to advance. However, during the LGM, despite cooler temperature than in MIS 3, the weakened south Asian monsoon and the associated reduced precipitation were not as favourable for glacier expansion as in MIS 3. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
15.
Peter Wilson Michael J. Bentley Christoph Schnabel Richard Clark Sheng Xu 《第四纪科学杂志》2008,23(5):461-473
Cosmogenic isotope (10Be and 26Al) surface exposure dating has been applied to valley‐axis and hillslope stone runs (relict periglacial block streams) and their source outcrops in the Falkland Islands, South Atlantic. The data indicate that stone runs are considerably older landforms than previously envisaged and afford no evidence that they are a product of the Last Glacial Maximum; the samples range in apparent 10Be age from 42k to 731k yr BP, but some of these are minima. The results indicate that valley‐axis stone runs may be up to 700–800k yr old, have simple exposure histories and are composite landforms that developed over several cold stages. Analyses of some hillslope and outcrop samples also demonstrate simple exposure histories with 10Be ages from 42k to 658k yr BP. In contrast, isotopic ratios from other hillslope and outcrop samples reveal they have had a complex exposure history involving periods of burial or shielding; the samples range in 10Be age from 59k to 569k yr BP and these are regarded as minimum age estimates. Larger stone runs may be older than smaller runs and there is a possibility that stone runs older than 800k yr exist in other parts of the Falklands. The assertion that glaciation in the Falklands was restricted to the highest uplands is supported by the data, and the potential for age determination of other boulder‐strewn and bedrock landforms, using cosmogenic isotope analysis, in order to extend the geochronology of Quaternary events and processes is noted. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
16.
Claus‐Dieter Hillenbrand James A. Smith Gerhard Kuhn Oliver Esper Rainer Gersonde Rob D. Larter Barbara Maher Steven G. Moreton Tracy M. Shimmield Monika Korte 《第四纪科学杂志》2010,25(3):280-295
Reliable dating of glaciomarine sediments deposited on the Antarctic shelf since the Last Glacial Maximum (LGM) is challenging because of the rarity of calcareous (micro‐) fossils and the recycling of fossil organic matter. Consequently, radiocarbon (14C) ages of the acid‐insoluble organic fraction (AIO) of the sediments bear uncertainties that are difficult to quantify. Here we present the results of three different methods to date a sedimentary unit consisting of diatomaceous ooze and diatomaceous mud that was deposited following the last deglaciation at five core sites on the inner shelf in the western Amundsen Sea (West Antarctica). In three cores conventional 14C dating of the AIO in bulk samples yielded age reversals down‐core, but at all sites the AIO 14C ages obtained from diatomaceous ooze within the diatom‐rich unit yielded similar uncorrected 14C ages between 13 517 ± 56 and 11 543 ± 47 years before present (a BP). Correction of these ages by subtracting the core‐top ages, which probably reflect present‐day deposition (as indicated by 210Pb dating of the sediment surface at one core site), yielded ages between ca. 10 500 and 8400 cal. a BP. Correction of the AIO ages of the diatomaceous ooze by only subtracting the marine reservoir effect (MRE) of 1300 a indicated deposition of the diatom‐rich sediments between 14 100 and 11 900 cal. a BP. Most of these ages are consistent with age constraints between 13.0 and 8.0 ka for the diatom‐rich unit, which we obtained by correlating the relative palaeomagnetic intensity (RPI) records of three of the sediment cores with global and regional reference curves. As a third dating technique we applied conventional radiocarbon dating of the AIO included in acid‐cleaned diatom hard parts extracted from the diatomaceous ooze. This method yielded uncorrected 14C ages of only 5111 ± 38 and 5106 ± 38 a BP, respectively. We reject these young ages, because they are likely to be overprinted by the adsorption of modern atmospheric carbon dioxide onto the surfaces of the diatom hard parts prior to sample graphitisation and combustion for 14C dating. The deposition of the diatom‐rich unit in the western Amundsen Sea suggests deglaciation of the inner shelf before ca. 13 ka BP. The deposition of diatomaceous oozes elsewhere on the Antarctic shelf around the same time, however, seems to be coincidental rather than directly related. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
17.
During the Last Glacial Maximum (LGM), long valley glaciers developed on the northern and southern sides of the High Tatra Mountains, Poland and Slovakia. Chlorine-36 exposure dating of moraine boulders suggests two major phases of moraine stabilization, at 26–21 ka (LGM I — maximum) and at 18 ka (LGM II). The dates suggest a significantly earlier maximum advance on the southern side of the range. Reconstructing the geometry of four glaciers in the Sucha Woda, Pańszczyca, Mlynicka and Velicka valleys allowed determining their equilibrium-line altitudes (ELAs) at 1460, 1460, 1650 and 1700 m asl, respectively. Based on a positive degree-day model, the mass balance and climatic parameter anomaly (temperature and precipitation) has been constrained for LGM I advance. Modeling results indicate slightly different conditions between northern and southern slopes. The N–S ELA gradient finds confirmation in slightly higher temperature (at least 1 °C) or lower precipitation (15%) on the south-facing glaciers during LGM I. The precipitation distribution over the High Tatra Mountains indicates potentially different LGM atmospheric circulation than at the present day, with reduced northwesterly inflow and increased southerly and westerly inflows of moist air masses. 相似文献
18.
Colin K. Ballantyne John O. Stone 《Boreas: An International Journal of Quaternary Research》2015,44(2):277-287
Trimlines separating glacially abraded lower slopes from blockfield‐covered summits on Irish mountains have traditionally been interpreted as representing the upper limit of the last ice sheet during the Last Glacial Maximum (LGM). Cosmogenic 10Be exposure ages obtained for samples from glacially deposited perched boulders resting on blockfield debris on the summit area of Slievenamon (721 m a.s.l.) in southern Ireland demonstrate emplacement by the last Irish Ice Sheet (IIS), implying preservation of the blockfield under cold‐based ice during the LGM, and supporting the view that trimlines throughout the British Isles represent former englacial thermal regime boundaries between a lower zone of warm‐based sliding ice and an upper zone of cold‐based ice. The youngest exposure age (22.6±1.1 or 21.0±0.9 ka, depending on the 10Be production rate employed) is statistically indistinguishable from the mean age (23.4±1.2 or 21.8±0.9 ka) obtained for two samples from ice‐abraded bedrock at high ground on Blackstairs Mountain, 51 km to the east, and with published cosmogenic 36Cl ages. Collectively, these ages imply (i) early (24–21 ka) thinning of the last IIS and emergence of high ground in SE Ireland; (ii) relatively brief (1–3 ka) glacial occupation of southernmost Ireland during the LGM; (iii) decoupling of the Irish Sea Ice Stream and ice from the Irish midlands within a similar time frame; and (iv) that the southern fringe of Ireland was deglaciated before western and northern Ireland. 相似文献
19.
Geomorphological evidences of post-LGM glacial advancements in the Himalaya: A study from Chorabari Glacier,Garhwal Himalaya,India 总被引：2，自引：0，他引：2
MANISH MEHTA ZAHID MAJEED D P DOBHAL PRADEEP SRIVASTAVA 《Journal of Earth System Science》2012,121(1):149-163
Field geomorphology and remote sensing data, supported by Optical Stimulated Luminescence (OSL) dating from the Mandakini
river valley of the Garhwal Himalaya enabled identification of four major glacial events; Rambara Glacial Stage (RGS) (13
± 2 ka), Ghindurpani Glacial Stage (GhGS) (9 ± 1 ka), Garuriya Glacial Stage (GGS) (7 ± 1 ka) and Kedarnath Glacial Stage
(KGS) (5 ± 1 ka). RGS was the most extensive glaciation extending for ~6 km down the valley from the present day snout and
lowered to an altitude of 2800 m asl at Rambara covering around ~31 km2 area of the Mandakini river valley. Compared to this, the other three glaciations (viz., GhGS, GGS and KGS) were of lower
magnitudes terminating around ~3000, ~3300 and ~3500 m asl, respectively. It was also observed that the mean equilibrium line
altitude (ELA) during RGS was lowered to 4747 m asl compared to the present level of 5120 m asl. This implies an ELA depression
of ~373 m during the RGS which would correspond to a lowering of ~2°C summer temperature during the RGS. The results are comparable
to that of the adjacent western and central Himalaya implying a common forcing factor that we attribute to the insolation-driven
monsoon precipitation in the western and central Himalaya. 相似文献
20.
NARAYANAPANICKER SURESH TRILOKI N. BAGATI ROHTASH KUMAR VIKRAM C. THAKUR 《Sedimentology》2007,54(4):809-833
Quaternary alluvial fans in the tectonically active Pinjaur Dun, an intramontane valley in the Sub‐Himalaya, were deposited in front of the Nalagarh Thrust and were influenced both by tectonics and glacial climate fluctuations. The surface morphology indicates that an earlier set of first‐order fans (Qf1) became entrenched and onlapped by a series of second‐order fans (Qf2). The younger fan segments were then cut by a pair of terraces (T1 and T2). Quartz optically stimulated luminescence dating establishes that the Qf1 aggradational phase was initiated before 96·5 ± 25·3 ka and terminated after 83·7 ± 16·3 ka. This was followed by a period of incision, before Qf2 fan deposition started at 72·4 ± 13·4 ka and continued until 24·5 ± 4·9 ka. Sediment was deposited on the T1 (upper) and T2 (lower) terraces at 16·3 ± 2·1 and 4·5 ka, respectively, recording a return to overall degradation punctuated by minor deposition on terraces. The period of incision separating the younger and older fan deposits coincided with enhanced SW monsoon precipitation. The subsequent development of the Qf2 fans and their progradation until 20 ka suggest erosional unloading of the thrust hangingwall during a tectonically quiescent phase. Toe cutting, deposition of axial river and lacustrine facies, and retreat of Qf2 around 45 ka, indicate fanward shift of the axial river due to tilting of the valley towards the NE in response to reactivation of the Nalagarh Thrust. The cessation of Qf2 deposition around 20 ka and the onset of through‐fan entrenchment suggest reduced sediment supply but relatively high stream power during the last glacial maxima (LGM). The prolonged stream incision since the cessation of Qf2 deposition, with only minor depositional phases at 16·3 ± 2·1 and 4·5 ka, resulted from high water discharge and low sediment input during intensification of the SW monsoon and vegetation changes in the hinterland. 相似文献