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Mapping and chronology of coversands and dunes from the Aquitaine basin, southwest France
Aeolian Research ( IF 3.1 ) Pub Date : 2020-09-02 , DOI: 10.1016/j.aeolia.2020.100628
Pascal Bertran , Eric Andrieux , Mark D. Bateman , Markus Fuchs , Michael Klinge , Fabrice Marembert

New stratigraphic (including GPR profiles) and chronological data provide a detailed understanding of the emplacement of aeolian sands in the Aquitaine basin (SW France). The main phase of coversand deposition ranges from 25 ka to 14 ka. The ages cluster around two periods that match Heinrich events (He-2 and He-1) and reflect increased sedimentation in response to aridification and high mean wind speeds. The age distribution is skewed toward recent phases, which likely results from continuous sand recycling. The dunes currently visible in the landscape were formed during the Younger Dryas/very early Holocene and the historical period. The Younger Dryas dunes are inland low parabolic dunes that have been strongly degraded. Only the last phases of the progression of the coastal dunefield are preserved because of coastal erosion. Two depositional phases have been identified, the Dark Ages Cold Period and the Little Ice Age, which correspond to phases of increased storminess already known from the coastal record in Europe. The Dark Ages Cold Period dunes are high parabolic dunes, whereas the Little Ice Age dunes are predominantly barchanoid. The impact of trampling of the dunes by cattle during the latter period, resulting in reduced vegetation cover, and their artificial stabilization by pine forests seems to be the plausible causes of this morphological difference. Overall, the Aquitaine aeolian system is a good example of a mid-latitude coastal to inland system that was intermittently active during the Quaternary, and where the reconfiguration of the coast following sea level fluctuations played an important role in the chronological distribution of sediments.



中文翻译:

法国西南部阿基坦大盆地的沙丘和沙丘的制图和年代学

新的地层(包括GPR剖面)和年代数据提供了对阿基坦盆地(法国西南部)中风沙沉积的详细了解。覆盖和沉积的主要阶段范围从25 ka到14 ka。年龄聚集在两个与Heinrich事件(He-2和He-1)相匹配的时期,反映了对干旱和高平均风速的沉积增加。年龄分布偏向最近的阶段,这可能是由于持续的沙子回收所致。当前在景观中可见的沙丘是在年轻的树蛙/非常早的全新世和历史时期形成的。较年轻的Dryas沙丘是内陆低抛物线沙丘,已被严重退化。由于海岸侵蚀,仅保留了沿海沙丘运动的最后阶段。已经确定了两个沉积阶段,即黑暗时期寒冷期和小冰期,这对应于欧洲沿海记录中已知的暴风雨增加阶段。黑暗时代的冷期沙丘是高抛物线的沙丘,而小冰期的沙丘主要是沙丘状的。在后期,牛践踏沙丘的影响导致植被覆盖率降低,松林人工稳定沙丘​​似乎是这种形态差异的合理原因。总体而言,阿基坦风积系统是中纬度沿海到内陆系统的一个很好的例子,该系统在第四纪期间断断续续地活跃,并且在海平面波动之后海岸的重新构造在沉积物的时间分布中起着重要作用。

更新日期:2020-09-02
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