A Holocene environmental record from the southern Yangtze River delta, eastern China
A Holocene environmental record from the southern Yangtze River delta, eastern China
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DOI：
10.1016/j.palaeo.2005.07.015
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发表时间：
2006-01
期刊：
影响因子：
--
通讯作者：
J. Tao;Min‐Te Chen;Shiyuan Xu
中科院分区：
文献类型：
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作者：
J. Tao;Min‐Te Chen;Shiyuan Xu
长江三角洲南部中全新世贝壳堤以西ZX-1孔的沉积记录包括泻湖相、盐沼相、潮坪相和湖沼相，反映了低能量沉积环境。全新世沉积物主要来源于周边太湖流域。大多数地球化学元素百分比的时间变化与从花粉记录推断的气候阶段相对应，即，相对低的SiO2、Na 2 O、CaO值和相对高的Al 2 O3、K2 O、MgO、Fe 2 O3、FeO、FeO+ Fe 2 O3和TiO 2值一般与温暖湿润的气候相一致，反之亦然。在季风控制下的长江三角洲南部，有三个地球化学指标--Al 2 O3/Na 2 O、K2 O/Na 2 O和CaO/K2 O--对过去的降水变化敏感。根据ZX-1孔细颗粒沉积物分析，在干旱气候条件下（年平均降水量（MAP）<500-900 mm）沉积的样品中，Al 2 O3/Na 2 O值往往小于12.2，而在湿润气候条件下（MAP）1000-1800 mm沉积的样品中，Al 2 O3/Na 2 O值大多大于12.2。同样，K2 O/Na 2 O边界值为2.0。然而，对于CaO/K2 O，干燥气候沉积物可能显示高于0.9的值，而潮湿气候沉积物的值通常小于0.9。这种地球化学响应表明，这些指标在解释季风控制的中国东部的古气候变化的潜在应用。重建了长江三角洲南部全新世气候变化历史。从8000年至7000年BP，区域气候表现出频繁的波动，温暖和潮湿的时期（8000-7700年BP; 7500-7200年BP）交替凉爽和潮湿的时期（7700-7500年BP; 7200-7000年BP）。从7000年到6000年BP，气候相对温暖和潮湿。从那时起，它变得凉爽干燥，在大约4000年前的一次强烈的寒冷事件中达到高潮。冷事件后，它变得温暖和潮湿，直到2500年BP左右。
The Holocene sedimentary record of core ZX-1, recovered west of mid-Holocene Chenier ridges on the monsoon-controlled Southern Yangtze delta, eastern China, consists of lagoon, salt marsh, upper tidal flat, and limnic facies, reflecting low-energy depositional environments. Holocene deposits mainly originated from the surrounding Tai Lake drainage basin. The temporal variation of most geochemical element percentages corresponds with the climatic phases inferred from the pollen record, i.e., the relatively low values of SiO2, Na2O, CaO and high values of Al2O3, K2O, MgO, Fe2O3, FeO, FeO+Fe2O3and TiO2generally concur with the warm and humid climate, and vice versa. Three geochemical indices − Al2O3/Na2O, K2O/Na2O, and CaO/K2O − are found to be sensitive to past precipitation in the monsoon-controlled southern Yangtze River delta. Based on fine sediment analysis of core ZX-1, the samples deposited under a dry climate with a mean annual precipitation (MAP) <500–900 mm tend to have Al2O3/Na2O values less than 12.2, and the samples deposited under a moist climate with an MAP 1000–1800 mm mostly have Al2O3/Na2O values higher than 12.2. Similarly, the K2O/Na2O boundary value is 2.0. However, for CaO/K2O, the dry climate sediments likely show values higher than 0.9, and those wet climate ones generally have values less than 0.9. This geochemical response suggests the potential application of these indices in the interpretation of palaeoclimate variation of monsoon-controlled eastern China. Holocene climatic variation history is reconstructed for the southern Yangtze delta. From 8000 to 7000 yr BP, regional climate demonstrated frequent fluctuations, with warm and wet periods (8000–7700; 7500–7200 yr BP) alternating with cool and less humid periods (7700–7500; 7200–7000 yr BP). From 7000 to 6000 yr BP, the climate was relatively warm and humid. Since then, it had turned cool and dry, climaxing in an intense cold event around 4000 yr BP. After the cold event, it became warm and humid until around 2500 yr BP.