Reconstruction of Holocene foreland progradation using optically stimulated luminescence (OSL) dating: an example from Dungeness, UK
Reconstruction of Holocene foreland progradation using optically stimulated luminescence (OSL) dating: an example from Dungeness, UK
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DOI：
10.1177/0959683607077034
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发表时间：
2007-05
期刊：
影响因子：
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通讯作者：
H. Roberts;A. Plater
中科院分区：
文献类型：
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作者：
H. Roberts;A. Plater
英国东南部的邓杰内斯前陆由一系列独特的砾石山脊组成，这些砾石山脊覆盖在潮下和潮间带砂上。光学激发发光（OSL）技术在Dungeness全新世潮间带砂的成功应用，为探索砾石前陆对海平面、风暴、沉积物供应和海岸动力变化的沉积响应提供了一个精确的年代学（精度~5%）。通过35个新的石英OSL年龄的三维网络揭示了Dungeness前陆沉积的性质，这些数据还约束了砾石侵位的时间。OSL年代学将西部下垫面早期形成时间定在~5000年前，年龄逐渐向东递减至~2000年前，位于现今前陆主体之下，1000 ~ 600年前位于东部现今前陆之下。下层砾石砂单元的最高OSL年龄为砾石的就位提供了最大限制年龄，与砾石表面有机沉积物的14C年龄一起为砾石的沉积提供了围封年龄。滨地砂沉积与砾石脊形成之间的滞后时间较短，表明砾石前陆沉积高度依赖于出露砂基底的预先存在。采用碎石下砂层OSL年龄并考虑下岩心OSL年龄构建的s型等时线显示出海岸响应的非线性；这表现为前陆沉积方向的变化，而不是沉积速率的时间变化。
Dungeness Foreland, southeast UK, is comprised of a series of distinctive gravel ridges overlying sub- and intertidal sands. The successful application of optically stimulated luminescence (OSL) to the Holocene sub- and intertidal sands at Dungeness provides a well-resolved chronology (precision ~5%) for exploring the sedimentary response of a gravel foreland to changes in sea level, storms, sediment supply and coastal dynamics. The nature of foreland progradation at Dungeness is revealed through a three-dimensional network of 35 new quartz OSL ages, and these data also constrain the timing of gravel emplacement. The OSL chronology places the early formation of the underlying shoreface in the west at ~5000 years ago, with ages decreasing progressively eastwards to ~2000 years ago beneath the main body of the present foreland, and 1000—600 years ago under the present-day ness in the east. The uppermost OSL ages for the subgravel sand unit provide maximum limiting ages for emplacement of the gravel, which together with 14C ages from organic deposits on the gravel surface provide bracketing ages for the deposition of the gravel. The short lag time between shoreface sand deposition and gravel ridge formation is indicative of a high degree of dependency of gravel foreland progradation on the pre-existence of an emergent sand substrate. Sigmoidal isochrons constructed using the subgravel sand OSL ages, and consideration of down-core OSL ages, demonstrates nonlinearity in coastal response; this is expressed in the form of changes in the direction of foreland progradation rather than temporal changes in sedimentation rate.