祁连山东段童子坝河阶地对气候变化与新构造运动的响应

通过对祁连山东段童子坝河各级阶地的年代和变形程度进行测定,得到了河流阶地的形成年代和过程,推算出民乐—大马营逆断裂的活动强度和速率,并分析了阶地形成和气候变化之间的关系。童子坝河5级阶地(年龄分别为16.70±1.81 calka BP、10 092.5±27.5 cal a BP、8127.5±72.5 cal a BP、2900±60 cal a BP、282.5±17.5 cal a BP)均形成于气候由冷转暖的阶段,属于气候成因阶地。基于断裂两侧阶地面的平面几何形态并结合上、下盘阶地横剖面同级阶地的高差,得到T4、T3、T2和T1阶地在民乐—大马营断裂处的垂直位错分别为10.6±3.1m、5.0±2.6 m、2.0±1.9 m和1.9±1.3 m,推算出全新世以来民乐—大马营断裂的垂直滑动速率为1.05±0.31 mm/a,水平缩短速率为1.02±0.60 mm/a。     

鲁北平原东部巨淀湖岩心沉积物记录的全新世环境演变

鲁北平原东部巨淀湖处于中国北方季风区,对全球气候变化响应敏感,为研究海岸带地区过去的气候环境演变提供了丰富的湖泊沉积资料。通过对巨淀湖钻孔岩心沉积物孢粉鉴定、粒度分析和AMS¹⁴C年代测定,探讨了鲁北平原地区8900 cal a BP以来的气候环境演变过程。结果表明: 8900—7625 cal a BP,气温较高,降水丰沛,气候较暖湿;7625—6810 cal a BP,气候整体呈变凉变干的趋势;6810—4435 cal a BP,温度回升,降水增加,显示了全新世中期整体温暖湿润的气候特征;4435—3150 cal a BP,气候整体寒冷湿润,其间也存在小幅的冷暖波动。中全新世期间5450—5280 cal a BP和4160—4090 cal a BP出现了明显冷干事件,这与中国乃至全球范围内的地质气候记录存在一致性,究其原因可能是受到太阳辐射变化导致的赤道辐合带南移、大洋海表温度变化以及地表植被的反馈作用的共同影响。     

浙江曹娥江下游XYC孔色度特征及其全新世环境记录*

XYC孔位于钱塘江南岸曹娥江下游地区。在对1717个样品的色度、粒度、总有机碳(TOC)测试分析的基础上,重点探讨该钻孔沉积物色度特征及环境意义,并结合年代框架讨论该地区环境变化特征。初步结论如下: (1)钻孔沉积物呈现高亮度、较低黄度和低红度特征,纵向看,①、②层色度波动明显,③层至⑧层下段色度变化稳定,⑧层上段至⑨层色度波动变化再次增强,呈波动—稳定—再波动特征。(2)亮度值与砂含量及TOC含量相关性较好,沉积动力强,砂含量高,亮度值高;TOC含量高,亮度值低。黄度、彩度值与TOC含量呈较好负相关,对气候的状况及海面变化有较好指示意义。(3)色度及其变化过程指示多水或水下沉积环境,并在一定程度上响应该地区海平面变化以及河流相—潮坪相—浅海相—湖沼相的沉积相变化过程: 9690—9107 cal a BP时段,该区以河流沉积为主,水动力变化不稳定,气候偏干,TOC含量较低,亮度高,红黄度低;9107—8613 cal a BP时段,黄度、彩度值降低,气候转湿,半咸水贝类生物及毕克卷转虫为主的底栖有孔虫的出现,表明研究区发生海侵并逐步由低潮坪转为高潮坪环境;8613—7330 cal a BP时段,黄度、彩度值最低,气候更湿润,伴有正常盐度的异地希望虫和少量抱球虫、圆辐虫等浮游有孔虫,海面进一步上升,成为浅海环境;7330—5131 cal a BP时段,黄度、彩度值升高,海面降低,气候变干,研究区转化为湖沼环境,泥炭发育。     

龙虎山丹霞地貌区河流阶地地貌面的热释光测年研究

采用热释光(TL)测年方法对龙虎山丹霞地貌区泸溪河的阶地进行了年代学研究,获得了低阶地沉积物的堆积年代及其阶地面的形成时代,该区河流主要发育两级阶地,T1阶地堆积于3 400~6 000 a B.P.,其地貌面形成于3 400~4 000 a,T2阶地堆积于7 600~11 200 a B.P.,该级地貌面形成于7 600~8 000 a B.P.。利用低阶地地貌面的年代学成果,推算出龙虎山丹霞地貌区地壳隆升速率为0.33~0.63 m/ka,根据这一速率推算得出,第一夷平面形成于6×104a左右,第二夷平面形成于28×104a左右。分布于这些夷平面上的丹霞地貌景观的年龄与此相当。     

全新世以来岱海盆地植被演替和气候变化的孢粉学证据

岱海盆地99A孔11.01 m以上地层较高分辨率的孢粉分析揭示了该区12 000 cal a BP以来的植被演替和气候变化. 早全新世时期, 岱海盆地受冬季风影响强烈, 气候波动以冷湿、暖干为主, 12 000～11 000 cal a BP为以白桦林为主的森林草原植被, 气候寒凉湿润; 11 000～7 900 cal a BP白桦林退缩, 气候温干; 中全新世时, 主要受控于夏季风影响下, 气候波动以冷干、暖湿为主, 7 900～4 450 cal a BP是岱海盆地森林植被发育最好的时期, 气候温暖湿润, 4 450～2 900 cal a BP森林开始退缩, 气候温干; 2 900～0 cal a BP在气候变凉干和人类活动的影响下, 森林植被几近消失.     

珠江三角洲中部晚更新世以来的有孔虫记录与古环境演化*

珠江三角洲中部钻孔PRD20和PRD17晚第四纪以来的沉积记录较为完整,尤其是晚更新世海侵记录良好。以其为研究对象,对两孔的有孔虫微体动物群记录和沉积特征进行了分析和对比,并结合前人研究成果,重建珠江三角洲晚更新世以来的古环境演变,并着重分析了晚更新世海侵事件。约44500 cal a BP以前,研究区为河流环境,发育河道砂砾沉积。约44500—21300 cal a BP,发生晚更新世海侵,形成溺谷型河口湾,两孔沉积物中有孔虫的垂直分布记录了水体条件发生的多次变化,可辨识出2次海侵海退次级旋回;其中PRD20孔中有孔虫以滨岸广盐型占绝对优势,PRD17孔中以滨岸广盐型为主、海相—半咸水型有孔虫占有一定比例,表明研究区位于溺谷湾中径流与潮流共同作用的区域,且PRD20孔受径流影响更大。约21300 cal a BP后,受末次冰盛期海退影响,研究区暴露于地表遭受风化剥蚀,风化产物在PRD20孔表现为1层褐红色砂砾,在PRD17孔表现为1层花斑黏土。约8000 cal a BP,海平面回升导致河水滞留形成沼泽环境,PRD20孔发育1层泥炭层。约8000—5500 cal a BP,PRD20孔发育受径流影响较大的河口湾湾头沉积,仅在全新世海侵最盛时含有少量有孔虫记录。约5500 cal a BP后,研究区发育三角洲平原沉积。受构造抬升影响,PRD17孔地势较高,于约4700 cal a BP才开始重新接受沉积,零星出现潮水搬运而来的有孔虫。     

中-晚全新世以来安固里淖气候演变的植硅体记录

河北坝上地区位于东亚季风边缘区和农牧交错带,季风强弱的变化深刻影响着该地区人类文明的发展.为了重建河北坝上地区中-晚全新世以来的气候演化过程,剖析气候变化与人类文明发展的关系,以坝上地区安固里淖湖为研究对象,通过对该湖沉积剖面植硅体的分析,并结合孢粉组合特征,恢复了安固里淖地区5 000 cal.a BP以来的气候演变历史.结果显示,在千年尺度上该区域气候总体呈冷干趋势,但在5 030~3 070 cal.a BP时期气候相对湿润,千年尺度上气候的变化主要受控于北半球太阳辐射量的变化.在百年尺度上安固里淖地区经历了7次冷干事件,分别发生于4 500 cal.a BP、4 100~3 800 cal.a BP、3 500 cal.a BP、3 000 cal.a BP、2 100 cal.a BP、1 100 cal.a BP和800~270 cal.a BP左右,这7次冷干事件对应于东亚季风减弱阶段,主要受到了北半球高纬气候和太阳活动的共同影响.该区人类文明的演化敏感响应于气候变化,气候温湿期以农业文明为主,气候冷干期以草原文明为主.      

鲜水河断裂带乾宁段晚第四纪走滑速率及区域强震危险性研究

活动断裂几何学特征及滑动速率是研究断裂运动学、动力学机制及其评估区域强震危险性的重要依据。青藏高原东缘左行走滑的鲜水河断裂带是控制高原物质向南东挤出的重要边界,是中国陆内活动性最强的断裂之一。本文以鲜水河断裂带北西段为研究对象,通过高精度遥感影像解译、野外考察、OSL(光释光)和¹⁴C测年方法以及LiDAR(激光雷达)扫描获得乾宁段龙灯乡冲积阶地的位错量和废弃年龄。T4和T3′水平位错量分别为106±5 m和77±2 m, T4阶地垂直位错量为9.6±0.5 m。T4和T3′阶地的废弃年龄分别为11±1 ka和7±1 ka。结合对应的年龄和位错量,得到乾宁段晚第四纪走滑速率左行走滑速率为10.5±1 mm/a,垂直滑动速率为0.9±0.1 mm/a,断层倾向北东,具有正断运动学特征。通过重新计算断裂两侧GPS矢量沿断裂方向分量,得到鲜水河断裂带炉霍段、炉霍—康定段、磨西段现今左行走滑速率分别约为8.1 mm/a、8.2 mm/a、9.4 mm/a,整体表现为自北西向南东递增。综合乾宁段晚第四纪走滑速率和最新强震活动的离逝时间估算,认为鲜水河断裂带乾宁段目前应变累积...     

青藏高原东缘宜宾地区第四纪河流沉积物中铁质重矿物特征及物源意义

大河流域的发育史和演化在地学界广受关注。探讨宜宾地区第四纪沉积物中铁质重矿物的特征,可为长江流域的演化提供重要证据,同时对于了解青藏高原东缘的隆升及沉积响应具有重要意义。本文以金沙江和岷江交汇处的宜宾地区第四纪沉积物中的铁质重矿物为研究对象,分析其在电子探针和背散射图像中的化学和形貌学特征,探究长江及其支流的物源演化过程。研究结果显示:岷江下游Ⅴ级阶地至Ⅳ级阶地沉积以磁铁矿为主,物源主要来自龙门山构造带;Ⅲ级阶地沉积以钛铁矿为主,物源仍然主要来自龙门山构造带;现代沉积中蓝晶石、磷灰石等包裹体的铁质矿物增多,其物源来自龙门山构造带和松潘—甘孜褶皱带。岷江Ⅴ级至Ⅲ级阶地形成时,岷江的源头主要位于龙门山构造带;Ⅲ级阶地形成以后,岷江不断向上溯源侵蚀,深入松潘—甘孜褶皱带内,逐渐形成现代岷江。金沙江Ⅴ级阶地和长江Ⅴ级阶地中均未出现攀枝花钒钛磁铁矿,此时金沙江攀枝花—宜宾河段未贯通,长江此时在研究区的物源主要由发源于龙门山构造带的岷江提供。金沙江Ⅳ级阶地中攀枝花钒钛磁铁矿大量出现,表明此时金沙江攀枝花—宜宾河段已经贯通,时间为Ⅳ级阶地开始沉积的时间,即0.5~0.3 Ma BP。     

莱州湾南岸全新世相对海平面变化重建

在对莱州湾南岸8个钻孔沉积物沉积结构及有孔虫特征分析基础上,识别相关海面标志层位,辅以加速器质谱AMS14C测年,重建了全新世相对海面变化历史,并讨论了海面变化的沉积响应及控制因素。约9200cal BP以前,海面快速上升,研究区海侵时海面于-21.5m左右;9200~8400cal BP海面上升速率减缓至约2mm/a;8400~8000cal BP海面由-14m快速上升至-5.5m,速率约为33mm/a;8000~7600cal BP,海面持续数百年停滞或微弱下降;7600~7000cal BP海面由-5.5m快速上升至0m以上,速率至少约为13mm/a;7000~6000cal BP海面缓慢上升至+2~+3m位置,速率约为3mm/a;约6000cal BP以后海面缓慢下降至现今水平。约9200cal BP以前、8400~8000cal BP、7600~7000cal BP时期的3次海面快速上升,是MWP-1C融水脉冲、诱发8.2ka冷事件的融水脉冲,以及MWP-2融水脉冲的中纬度地区响应。中全新世全球冰融趋于停滞后,由于研究区沉积盆地沉降速度较慢,在冰川均衡调整效应下,使+2~+3m的相对高海面得以呈现。     

Revisiting Late Quaternary Slip-rate along the Maqu Segment of the Eastern Kunlun Fault,Northeast Tibet

The Late Quaternary slip rate along the Maqu segment of the eastern Kunlun Fault was estimated using a combination of high-resolution remote sensing imagery interpretation, field observations and differential Global Positioning System(GPS) measurements of offset river terraces, and 14 C dating of snail shells collected from offset risers. The results show that the left-slip rate along the segment is 3–5 mm/a, and that the vertical slip rate is 0.3–0.5 mm/a. Both the horizontal and vertical slips on the segment remain consistent over a distance of ~100 km. It means that no slip gradient as previously suggested occurred along the Maqu segment, and which thus might behave as an independent seismogenic fault. Judging from multiple relationships among young terrace offsets, we infer that co-seismic surface rupture produced by a characteristic earthquake with a magnitude of Ms7.0–7.5 on the Maqu fault could generate a horizontal slip of 4.5–5 m and a vertical slip of 0.45–0.5 m, with a corresponding ratio(Dh/Dv) of about 9. Two surface rupture events must have occurred over the past 3300 years, the latest one possibly between 1485 cal BP and 1730 cal BP.     

渤海湾西岸现代岸线钻孔记录的全新世沉积环境与相对海面变化

以渤海湾西岸现代岸线附近的NP3、CH110和BT113三个钻孔全新世岩心为研究对象,采用沉积岩石学、AMS ¹⁴C(accelerator mass spectrometry ¹⁴C,加速器质谱¹⁴C)测年、微体生物聚类分析等方法精细判别沉积相,重建渤海湾西岸全新世沉积演化历史,并利用微体生物组合分带对水深变化的指示,定量讨论全新世相对海面变化。结果表明:渤海湾西岸全新世受海陆交互作用影响,经历了沼泽-潮滩-浅海-前三角洲-三角洲前缘-三角洲平原环境的演化过程。全新世初始阶段,研究区中部和北部发育沼泽环境,南部未见沉积,与上更新统河流相沉积呈不整合接触。全新世早期,研究区潮滩环境发育。潮滩层厚度约1 m,历时数百至1千余年。至7000 cal BP前后水深增大,研究区进入浅海环境。约6000 cal BP,沿岸南北两端先后进入三角洲过渡环境,中部三角洲环境约开始于1500 cal BP。渤海湾西岸地区全新世的环境演化同时记录了该地区的相对海面变化:约10000 cal BP前后,渤海湾相对海平面已接近21.3~20.4 m。约8000 cal BP,相对海平面介于18.6~17.0 m。约6000 cal BP时相对海平面低于6.8 m,5000~1000 cal BP,相对海平面高于-2.5 m,1000~800 cal BP,相对海平面介于-1.3~-0.4 m。8000~5000 cal BP时,相对海面上升约15.0 m,上升速率达5 m/1 ka。     

色尔腾山山前断裂大后店—瓦窑滩段的地貌特征与分段

色尔腾山山前断裂位于阴山山脉的中西段,控制着临河凹陷的北缘,在晚第四纪以来有着强烈的活动。通过对色尔腾山山前断裂大后店—瓦窑滩段进行地貌调查和测量,认为该段并不是一条向NE方向突出的单一弧形断裂,而是由走向为EW向的红旗村段(大后店—乌不浪口)和走向为NW向的圐圙补隆段(乌不浪口—瓦窑滩)组成。整条断裂共发育4级台地,T3台地的形成时代在距今5万至7万年以前,是河套古大湖的湖滨相沉积;T2的形成时代在距今2万至3万年以前。而全新世T1台地在该两段上的分布并不相同,红旗村段和圐圙补隆段T1台地的平均高度分别为537 m和81 m,测得的台地年龄分别为623 ka和1236 ka,沉积物均为冲洪积砂砾。两段断裂全新世的滑动速率分别为086 mm/a和065 mm/a。这两段在几何展布、构造地貌、断层运动学性质方面有不同的特征,属于不同的活动断裂分段,其分段边界的类型为断裂交汇处的T型结点。     

Holocene shore displacement and deglaciation chronology in Norrbotten, Sweden

The coastal zone of Norrbotten, northern Sweden, was gradually inundated by the Ancylus Lake following the retreating ice margin and forming a highest coastline approximately 210 m above the present sea level. The succeeding shore displacement is reconstructed based on lithological investigations and radiocarbon datings of identified isolation sequences from 12 cored lake basins. The highest lake basins, along with two basins above the highest shoreline, suggest ice-free conditions already at 10 500 cal. yr BP. This is at least 500 years earlier than previously thought and implies rapid ice-sheet break-up in the Gulf of Bothnia. The shore displacement (RSL) curve represents a forced regression of successively decreasing rate through the Holocene, from 9 m/100 yr to 0.8 m/100 yr. During the first 1000-1200 years, the isostatic uplift is exponentially declining, followed by a constant uplift rate from c. 9500 cal. yr BP to 5500-5000 cal. yr BP. The last 5000 years seem to be characterized by a low but constant rebound rate. The development of the Ancylus Lake stage of the Baltic may also be discerned in the Norrbotten RSL curve, suggesting that the chronology of the Ancylus Lake stages may have to be revised. The Littorina transgression is also reflected by the RSL curve shape. In addition, a series of early to mid-Holocene beach terraces were OSL-dated to allow for comparison with the ¹⁴C-dated shore displacement curve. Interpretations of these ages and their relation to former sea levels were clearly more problematic than the dating of the lake basin isolations.     

台湾头社盆地湖沼相沉积孢粉记录的6.2~1.3 cal ka BP以来气候研究

头社盆地位于中国台湾省中部,东亚季风区的最前沿,对东亚季风的响应十分敏感,研究其中晚全新世以来古植被、重建古气候序列,探讨其气候与东亚夏季风的关系具有重要的科学意义。文章对头社盆地泥炭—湖泊沉积的AMS14C测年、体积磁化率测试的基础上,基于孢粉记录,重建晚全新世来植被变化,恢复古气候。结果表明全新世中晚期以来分六个阶段：6.2~6.0 cal ka BP,气候凉干,植被类型是亚热带常绿阔叶林;6.0~4.0 cal ka BP,气候转暖湿,植被类型为含较多热带成分的亚热带常绿阔叶林;4.0~2.2 cal ka BP,气候相对凉干,植被类型转为亚热带常绿阔叶林;2.2~1.9 cal ka BP,气候又变暖湿;1.9~1.7 cal ka BP,气候快速冷干事件,森林退化;1.7~1.3 cal ka BP,气候重转温暖湿润,植被类型为接近现代的沼泽草原。整体上6.2~2.2 cal ka BP的气候变化是由温暖湿润向温凉干燥转变的趋势,这是全新世中晚期以来的太阳辐射量减少所导致的,太阳辐射量的减少导致热带辐合南移,进而导致东亚夏季风减弱,而2.2 cal ka BP之后气候波动较大,可能是在东亚夏季风减弱的背景下,ENSO活动加强与人类活动的干扰下耦合的结果。     

南海北部琼东南盆地第四系陆架边缘轨迹迁移及深水沉积模式

陆架边缘迁移轨迹综合受控于构造、物源、海平面和气候等多种因素,其迁移演化与深水沉积体系发育关系密切。陆架边缘迁移规律及沉积物输送体制与深水砂体预测是当前国际地学领域的热点议题。本文通过基于琼东南盆地新采集的高精度地震资料,定量表征了第四系陆架边缘轨迹,识别了低角度缓慢上升型、中等角度上升型和高角度急剧上升型等3类陆架边缘轨迹类型。2.4 Ma以来,陆架边缘轨迹时空演化可分为3个阶段且具有侧向差异性:2.4~1.9 Ma以低角度缓慢上升型为主,1.9~0.8 Ma西北部以低角度缓慢上升型为主,东北部则以中等角度上升型为主,0.8 Ma至今西北部以中等角度上升型为主,东北部以高角度急剧上升型为主。琼东南盆地第四系陆架边缘迁移轨迹研究表明:当陆架边缘轨迹角0°<α<4°时,陆坡区峡谷规模较小且下切浅,深海平原区发育多期大型海底扇沉积,块体搬运沉积(MTDs)较少;当4°<α<35°时,陆坡区峡谷规模有所增加,深海平原区海底扇沉积与块体搬运沉积均有出现;当35°<α<90°时,陆坡区峡谷发育较少但下切深,深水平原区沉积以大型块体搬运沉积为主,海底扇几乎不发育。琼东南盆地更新世以来气温不断下降,以及东亚冬季风的显著增强,物源供给增强加之海平面的下降进而导致了西北部陆架边缘表现为进积特征;研究区东北部的断裂活动频繁以及物源供给弱,导致了研究区东北部陆坡推进距离远远小于研究区西北部且发育多期次块体搬运沉积物。以上认识对南海北部陆架边缘体系及深水扇预测具有一定的理论意义。     

断陷盆地缓坡带河流沉积砂体定量表征及控制因素分析:以霸县凹陷文安斜坡东营组三段为例

断陷湖盆缓坡河流成因砂体是重要的油气储集单元.根据岩心观察、钻井岩/电特征并结合地震沉积学方法,分析断陷湖盆缓坡河流沉积体系和砂体时空分布特征,能为油气精细勘探提供可靠的依据.研究表明,霸县凹陷文安斜坡中部东营组三段周期性地发育4条呈NE-SW辫-曲复合型河流沉积,由河道沉积、砂坝沉积和泛滥平原沉积3种亚相以及辫状河道...     

Holocene environmental evolution recorded by core sediments of Judian Lake in the east of Lubei Plain,Shandong Province

Judian Lake in the east of Lubei Plain is located in the monsoon area of northern China,which is sensitive to global climate change and provides abundant lake sedimentary data for the study of the past climate and environment evolution in the land-sea interaction area. Based on the sporopollen identification,grain size analysis and AMS¹⁴C dating of core sediments from the drilling hole of the Judian Lake,the evolutional process of climate and environment since 8900 cal a BP in the northern Lubei Plain was discussed. The results show that: 8900-7625cal a BP,the temperature and precipitation increased and the climate changed from cold-dry to warm-wet;7625—6810 cal a BP,the overall climate was becoming cooler and drier;6810—4435cal a BP,the temperature rose and the precipitation increased,showing an overall warm and humid climate in the middle Holocene;4435—3150cal a BP,the climate was generally cold and humid with some low-amplitude fluctuations of cold and warm. During the middle Holocene,there were two obvious cold and dry events in 5450—5280cal a BP and 4160—4090cal a BP,which was consistent with the geological and climatic records in China and even in the world. It may be due to the southward movement of the equatorial convergence zone caused by the change of solar radiation,the change of ocean surface temperature and the feedback of surface vegetation.     

Fluvial system response to external forcing and human impact – Late Pleistocene and Holocene fluvial dynamics of the lower Guadalete River in western Andalucía (Spain)

The 170 km long river course of the Guadalete River (western Andalucía) provides an excellent record of Late Pleistocene and Holocene fluvial sedimentation dynamics. Furthermore, its floodplain sediments are very well suited to describe geomorphic changes forced by climate fluctuations, sea‐level changes, tectonic influences and human activity. Multiproxy investigations were based on field mapping and the study of 18 profile sections, mainly including sedimentological characterisation, soil‐chemical analyses and radiocarbon dating of 34 samples. Findings were complemented by drillings and electrical resistivity tomography. The lowermost 50 km of the river section are divided into an upper and lower part (each 25 km long), based on different sediment preservation conditions. The boundary corresponds to the disappearance of the Late Pleistocene river terrace. Significant floodplain aggradation occurred at around 10 000 cal. years BP, while dynamics were strongly affected by sea‐level fluctuations until the early Holocene. Furthermore, sedimentation starting at 8000, 6100, 4600, 2200, 900 and 400 cal. years BP is related to enhanced fluvial dynamics due to environmental stress that presumably was triggered by climate fluctuations, that is, aridification. However, the strongest intensity of sedimentation at 400 cal. years BP points to climate anomalies in the course of the Little Ice Age. In contrast, several periods of stability associated with alluvial soil formation took place during the Bølling and Allerød interstadials, prior to 8000, 6100 and 5100, and after 4300 and 2000 cal. years BP. The anthropogenic signal in floodplain evolution is not clearly distinguishable from that of climate. However, human land use had the potential to amplify geomorphic processes, especially during periods of climate deteriorations that caused increasing stress on the environment.