Optically stimulated luminescence (OSL) dating of fine-grained (4–11 μm) fluvial sediments is rarely attempted but is crucial for constraining the evolution of mud-dominated floodplains. This study investigated the applicability of OSL dating to fine-grained deposits in the Mekong River, Cambodia based on a very young (<600 yr) point-bar to riverbank succession and modern flood deposits. In succession, fine-grained quartz OSL provided the youngest ages, whereas age estimates by multi-grain sand-sized quartz OSL, and feldspar and polymineral infrared-stimulated luminescence are >200 years older than the fine-grained quartz OSL age estimates. Ages of fine-grained quartz OSL are concordant with the minimum ages obtained from the single-grain quartz OSL. These results are supported by the generally small residual doses (<0.1 Gy) measured in modern fine-grained floodplain deposits. This indicates that fine-grained sediments in the Mekong River (Cambodia) are sufficiently bleached at deposition and can yield reliable quartz OSL ages for establishing the chronology of the floodplain. The sufficient bleaching of fine-grained quartz partly results from the long transport distance and may also occur in other large river systems.

中文翻译：

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OSL可用于柬埔寨湄公河洪泛区细颗粒河流沉积物

很少尝试对细颗粒（4-11μm）河流沉积物进行光激发发光（OSL）测年，但对于限制以泥浆为主的洪泛区的演化至关重要。这项研究基于非常年轻（<600年）的河岸演替和现代洪水沉积的临界点，研究了OSL在柬埔寨湄公河细颗粒沉积物中的适用性。细粒石英OSL相继提供了最年轻的年龄，而多粒砂粒大小石英OSL的年龄估算，长石和多矿物红外激发发光的年龄比细粒石英OSL的年龄估算的年龄大了200年。细粒石英OSL的年龄与从单粒石英OSL获得的最小年龄一致。这些结果由通常较小的残留剂量（<0。1 Gy）以现代细粒洪泛区矿床测得。这表明湄公河（柬埔寨）中的细颗粒沉积物在沉积时被充分漂白，并且可以产生可靠的石英OSL年龄，以建立洪泛区的年代。细粒石英的充分漂白部分是由于运输距离长，在其他大型河流系统中也可能发生。