The role of sea-level rise, monsoonal discharge and the palaeo-landscape in the early Holocene evolution of the Pearl River delta, southern China
The role of sea-level rise, monsoonal discharge and the palaeo-landscape in the early Holocene evolution of the Pearl River delta, southern China
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DOI：
10.1016/j.quascirev.2012.01.002
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发表时间：
2012-10
影响因子：
4
通讯作者：
Y. Zong;Kangyou Huang;F. Yu;Zhuo Zheng;A. Switzer;Guangqing Huang;Ning Wang;Min Tang
中科院分区：
文献类型：
--
作者：
Y. Zong;Kangyou Huang;F. Yu;Zhuo Zheng;A. Switzer;Guangqing Huang;Ning Wang;Min Tang
根据珠江三角洲一个主要古河谷的沉积物岩心资料，重建了珠江三角洲全新世早期的历史。沉积和微体化石硅藻分析结合放射性碳测年提供了新的证据之间的相互作用海平面上升，前期地形和三角洲盆地内的沉积流量变化，因为末次冰期。这些新的记录表明，末次冰期的河道切割到约-40米处，进入一个更古老（可能是MIS5年龄）的海相层序，形成三角洲盆地的底部，主要存在于c。低于目前平均海平面10米至15米。冰后期海平面的快速上升淹没了全新世开始的切割山谷，在c之前。9000口径1960年，海洋泛滥主要局限在这些切割的山谷中。切割山谷有限的可容纳空间，加上强烈的季风驱动的淡水，高泥沙排放和一段时间的海平面快速上升意味着沉积速率非常高。向C方向。八千口径2000年，随着海平面上升到约-5米，海水从切割的山谷溢出，海水淹没了整个三角洲盆地。结果，珠江口被迫后退至三角洲盆地的顶点，盆地内的水盐度显著增加，原来封闭的系统分散到整个盆地，沉积作用由河流为主转变为潮汐为主。海平面继续上升，尽管在8000至7000卡尔之间的速度大大降低。30年BP，三角洲沉积集中在盆地顶部附近。在最后7000卡路里期间。30年BP，三角洲岸线向海推移，沉积作用由潮汐作用为主逐渐转变为河流作用为主。
The early Holocene history of the Pearl River delta is reconstructed based on a series of sediment cores obtained from one of the main palaeo-valleys in the basin. Sedimentary and microfossil diatom analyses combined with radiocarbon dating provide new evidence for the interactions between sea-level rise, antecedent topography and sedimentary discharge changes within the deltaic basin since the last glacial. These new records show that river channels of last glacial age incised down to c. −40 m into an older (possibly MIS5 age) marine sequence which forms the floor of the deltaic basin and exists primarily at c. 10 m–15 m below present mean sea level. Rapid postglacial sea-level rise flooded the incised valleys by the beginning of the Holocene, and prior to c. 9000 cal. years BP, marine inundation was largely confined within these incised valleys. The confined available accommodation space of the incised valleys combined with strong monsoon-driven freshwater, high sediment discharge and a period of rapid rising sea level meant that sedimentation rates were exceptionally high. Towards c. 8000 cal. years BP as sea level rose to about −5 m, marine inundation spilled out of the incised valleys and the sea flooded the whole deltaic basin. As a result, the mouth of the Pearl River was forced to retreat to the apex of the deltaic basin, water salinity within the basin increased markedly as the previously confined system dispersed across the basin, and the sedimentation changed from fluvial dominated to tidal dominated. Sea level continued to rise, albeit at a much reduced rate between 8000 and 7000 cal. years BP, and deltaic sedimentation was concentrated around the apex area of the basin. During the last 7000 cal. years BP, the delta shoreline moved seawards, and the sedimentary processes changed gradually from tidal dominated to fluvial dominated.