Sequence architecture of ancient rocky shorelines and their response to sea-level change: an Early Jurassic example from South Wales, UK
Sequence architecture of ancient rocky shorelines and their response to sea-level change: an Early Jurassic example from South Wales, UK
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古代岩石海岸线的层序结构及其对海平面变化的响应：来自英国南威尔士的早侏罗世例子
DOI：
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发表时间：
2006
影响因子：
2.7
通讯作者：
T. Sheppard
中科院分区：
文献类型：
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作者：
T. Sheppard
南威尔士格拉摩根（Glamorgan）的海边奥格莫尔（Ogmore-by-Sea）的海崖，暴露出一系列覆盖着岩石古台地的早侏罗世近岸碳酸盐。层序地层学解释可以识别出四个逆退叠合的准层序，每个层序的内部相结构都受下伏海岸台地的测深和几何形状控制。保存相被解释为前滨、滨面和近海环境的代表。虽然没有潮上相，但由于海平面上升导致海岸线后退期间后海岸的相互蚕食，所有岩相中都保留了具有代表性的风暴阶地碎屑组合。生物地层校准可以重建海平面历史，并将英国南部Rhaetian-Sinemurian地区重要的洪水面与当代海岸线的位置进行对比。这表明南威尔士的台地切口发生在大沉积开始前几百万年；因此，古岩岸台地上的取代沉积物可能不能代表海岸切割发生时的环境。作为同类中最好的例子之一，奥格莫尔的岩岸是世界各地古代岩岸的沉积系统模型。
The sea-cliffs of Ogmore-by-Sea in Glamorgan, South Wales, expose a succession of Early Jurassic nearshore carbonates that drape rocky palaeoplatforms. A sequence-stratigraphic interpretation allows the recognition of four retrogradationally stacked parasequences, the internal facies architecture of each of which is controlled by the bathymetry and geometry of the underlying shore platforms. Preserved facies are interpreted as representative of foreshore, shoreface and offshore environments. Supratidal facies are absent, but representative storm-terrace clast assemblages are preserved in all lithofacies as a result of the cannibalization of the backshore during periods of shoreline retreat driven by sea-level rise. Biostratigraphical calibration allows the reconstruction of sea-level history and the correlation of regionally important flooding surfaces in the Rhaetian–Sinemurian of Southern Britain with the position of the contemporary shoreline. This suggests that platform incision in South Wales occurred several million years before the onset of major deposition; superseding deposits above ancient rock shore platforms may therefore not be representative of the environment in which coastal incision took place. As one of the best examples of its kind, the rockshore at Ogmore acts as a deposystem model for ancient rocky shores worldwide.