Optical dating of Holocene tidal deposits from the southwestern coast of the South Yellow Sea using different grain-size quartz fractions
Optical dating of Holocene tidal deposits from the southwestern coast of the South Yellow Sea using different grain-size quartz fractions
复制标题
使用不同粒度石英组分对南黄海西南海岸全新世潮汐沉积物进行光学测年
DOI：
10.1016/j.jseaes.2016.12.036
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发表时间：
2017-03-01
影响因子：
3
通讯作者：
Yin, Yong
中科院分区：
文献类型：
--
作者：
Gao, Lei;Long, Hao;Yin, Yong
潮滩沉积为古环境研究提供了理想的沉积记录。可靠的年表对于利用这一档案破译环境变化的历史至关重要。在这项研究中，我们使用了南黄海西岸沉积岩芯(YZ07)的粗粒(CG，90-200微米)和细粒(FG，4-11微米)石英萃取物，对一个全新世潮坪层序进行了光致发光(OSL)测年。研究了这两种粒度组分的发光特性，并系统地比较了它们的光致发光年龄。结果表明，大多数潮坪沉积物具有良好的漂白性，其FG石英年龄与CG石英年龄基本一致，但也有部分样品的CG年龄被低估，这可能是由于CG石英中的钾长石混染所致。因此，我们应用了后红外光致发光测年和脉冲光致发光测年技术，克服了长石污染带来的问题，得到了与FG光致发光年龄相同的年龄。所有的OSL年龄一般都是按地层顺序排列的；相比之下，C-14年龄则更加无序，具有严重反转的特点。最后，基于30个OSL年龄和1个可接受的放射性碳年龄，建立了本研究潮滩层序的年龄框架。根据年龄-深度模型，确定了沉积速率变化的三个主要时期。这些SR变化可能与海平面升降历史、沉积中心向陆/向海运动以及全新世三角洲启动时期沉积过程的转换有关。沉积环境的变化也反映在研究区潮滩沉积的沉积学特征上。(C)2016爱思唯尔有限公司。保留所有权利。
The tidal flat deposit provides ideal sedimentary records for paleoenvironmental studies. Reliable chronology is crucial to utilize this archive for deciphering the history of environmental changes. In this study, we applied optically stimulated luminescence (OSL) dating method to a Holocene tidal flat sequence using both coarse-grained (CG, 90-200 mu m) and fine-grained (FG, 4-11 mu m) quartz extracts from a sedimentary core (YZ07) in western coast of the South Yellow Sea. The luminescence characteristics of the two grain-size fractions were investigated and then their resulting OSL ages were systematically compared. The results suggested that most tidal flat deposits are well bleached and their FG quartz ages are generally consistent with CG quartz ages, while some samples have CG ages underestimated compared with FG, likely resulted from the K-feldspar contamination for CG quartz. Hence, we applied post-IR OSL dating and pulsed OSL dating techniques; they could overcome the problems caused by feldspar contamination, and yielded identical dates as FG OSL ages. All OSL ages are generally in stratigraphic order; in contrast, the C-14 ages are much more disorder and characterized with severe inversions. Finally, the age framework of the tidal flat sequence under this study was constructed based on the 30 OSL ages and one acceptable radiocarbon age. According to the age-depth model, three main periods of sedimentation-rate (SR) variation were identified. These SR changes are probably associated with sea level rise fall history, and the depocenter landward/seaward movement as well as the transition of depositional process within the Holocene delta initiation. The depositional environment changes were also reflected in sedimentological features of the tidal flat deposits in our study area. (C) 2016 Elsevier Ltd. All rights reserved.