科研之友
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摘要
The morphogenesis and inner structure of the Holocene foredune plain in the Narva-Joesuu area, eastern Gulf of Finland, were studied using optically stimulated luminescence (OSL) dating, ground-penetrating radar (GPR) study and interpretation of airborne LIDAR elevation data. The results show that the Narva-Joesuu foredune plain consists of ca. 100 parallel coastal foredune ridges built of well-sorted fine sand underlain by gently (similar to 7 degrees) seaward-dipping sandy beach deposits. The distal part of the plain, which consists of at least 15 ridges, formed during the regressive phase of the Ancylus Lake/Early Litorina Sea, serving as a barrier for the lagoon behind it. A larger portion of ridges, with an average progradation rate of 0.26 m a(-1), formed under conditions of falling relative sea level during the Litorina regression and was separated from the older foredune succession by a hiatus related to the Litorina transgression at 8.5-7.3 cal. ka BP. In the highest central part of the plain the foredune growth was interrupted by foredune instability and a re-blowing episode dated to 5.4 +/- 0.9 ka BP which may correlate with a larger regional cooling at 5.8-5.1 cal. ka BP in the North Atlantic and central Europe. During the last 3000 years, the foredune progradation rate decreased to 0.19 m a(-1), most probably because of decelerated land-uplift and increased human impact due to coastal protection.
- 出版日期2013
