Mid- to late Holocene geomorphological and hydrological changes in the south Taihu area of the Yangtze delta plain, China
Mid- to late Holocene geomorphological and hydrological changes in the south Taihu area of the Yangtze delta plain, China
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DOI：
10.1016/j.palaeo.2018.03.012
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发表时间：
2018-06-01
影响因子：
3
通讯作者：
Yu, Xuening
中科院分区：
文献类型：
--
作者：
Chen, Ting;Ryves, David B.;Yu, Xuening
中国长江下游的太湖平原是新石器时代的稻作农业中心。然而，对于这个对海平面变化高度敏感的沿海低地来说，这一时期水稻种植迅速发展的原因尚未完全清楚。为了加深对史前水稻农业演化的地貌和水文背景的了解，在太湖平原南部的东苕溪平原收集了两个沉积物岩心（DTX4和DTX10），并进行了放射性碳测年、硅藻、有机碳和氮稳定同位素（δC-13和δN-15）、粒度和岩性分析。这些多代理分析表明，在大约之前。 7500 卡路里BP年前，东苕溪平原是一个快速扩张的高盐度河口（古太湖河口）。大约之后。 7500 卡路里今年BP，由于长江淡水流量强劲，低盐度条件普遍存在。随后，海水渗透，盐沼在大约 10 至 10 年间发展。 7000 和 6500 卡路里。由于海平面相对加速上升，导致 BP 下降。先前研究的多项沉积物记录表明，这次海侵事件在全新世期间影响了太湖平原的大片区域。由于古太湖河口的急剧收缩/关闭，形成了持续的淡水沼泽（或地下土地）。 5600 卡路里年BP，海平面相对稳定。我们推测，东苕溪平原的地貌和水文变化对新石器时代太湖平原的农业发展发挥了重要作用。大约在大约 10 年后，古太湖河口关闭并形成稳定的淡水沼泽（或陆地）。 5600 卡路里年BP是良渚时期（5500-4500cal.yr BP）水稻生产力迅速提高的关键前提。这一发展改变了地貌和河流系统，从而为太湖平原提供了充足的淡水供应。
The Taihu Plain of the Lower Yangtze valley, China was a centre of rice agriculture during the Neolithic period. Reasons for the rapid development of rice cultivation during this period, however, have not been fully understood for this coastal lowland, which is highly sensitive to sea-level change. To improve understanding of the geomorphological and hydrological context for evolution of prehistoric rice agriculture, two sediment cores (DTX4 and DTX10) in the East Tiaoxi River Plain, south Taihu Plain, were collected, and analysed for radiocarbon dating, diatoms, organic carbon and nitrogen stable isotopes (delta C-13 and delta N-15), grain size and lithology. These multiproxy analyses revealed that prior to ca. 7500 cal. yr BP, the East Tiaoxi River Plain was a rapidly aggrading high-salinity estuary (the Palaeo-Taihu Estuary). After ca. 7500 cal. yr BP, low salinity conditions prevailed as a result of strong Yangtze freshwater discharge. Subsequently, seawater penetration occurred and saltmarsh developed between ca. 7000 and 6500 cal. yr BP due to accelerated relative sea-level rise. This transgression event influenced a large area of the Taihu Plain during the Holocene, as shown by multiple sediment records from previous studies. Persistent freshwater marsh (or subaerial land) formed due to dramatic shrinkage/closure of the Palaeo-Taihu Estuary after ca. 5600 cal. yr BP when sea level was relatively stable. We speculate that geomorphological and hydrological changes of the East Tiaoxi River Plain played an important role in agricultural development across the Taihu Plain during the Neolithic period. The closure of the Palaeo-Taihu Estuary and the formation of stable freshwater marsh (or subaerial land) after ca. 5600 cal. yr BP were critical preconditions encouraging the rapid rise of rice productivity in the Liangzhu period (5500-4500 cal. yr BP). This development changed the landscape and river systems, and thus provided adequate freshwater supply to the Taihu Plain.