The dry Holocene Megathermal in Inner Mongolia
The dry Holocene Megathermal in Inner Mongolia
复制标题
DOI：
10.1016/s0031-0182(03)00225-6
复制
发表时间：
2003-04-15
影响因子：
3
通讯作者：
Chen, YC
中科院分区：
文献类型：
--
作者：
Chen, CTA;Lan, HC;Chen, YC
根据内蒙古盐海子湖16.22m长的沉积物柱样，重建了14 kyr BP（C-14年龄）以来的古气候。在沙丘重新活跃的湖泊收缩阶段，粗沉积物沉积在那里。这些沉积物有机碳含量较低，但成熟度指数较高，表明它们是在一种相对温和的环境中沉积的。与此相反，基于高有机含量和低成熟度指数，细沉积物沉积在高湖站在潮湿的环境。在8.0和4.3 kyr BP之间，它通常是干燥的。上述干、湿阶段与其他地区干旱-半干旱过渡带的记录一致，但与中国东部地区普遍认为的湿润全新世大暖期和台湾高山退湖的新重建记录不同。这种差异可能是由于这两个地区的湿度变化相对不敏感，因为它们都受到夏季季风的影响。另一方面，在夏季风北方边界附近的温暖气候中，燕海子湖较高的季风降水导致的蒸发增强降低了有效湿度。这也解释了冲绳海槽和南海北方的全新世高温大暖期与盐海子湖的干旱期相对应的事实。相反，4-2-kyr BP全新世最冷的时期对应于一个湿相在湖燕海子。(C)2003 Elsevier Science B. V.保留所有权利。
The paleoclimate since 14 kyr BP (C-14 age) was reconstructed based on a 16.22-m-long sediment core collected from Lake Yanhaizi, a saline lake located near the northern limit of the East Asian summer monsoon in Inner Mongolia. Coarse sediments were deposited there during a shrinkage phase of the lake when sand dunes reactivated. These sediments have low organic carbon contents but high maturity indices, indicating that they were deposited in an and environment. By contrast, based on high organic contents and low maturity indices, fine sediments were deposited during periods of high lake stand in a humid environment. It was in general dry between 8.0 and 4.3 kyr BP. The above dry and wet phases are consistent with those recovered from the arid-semiarid transition zone elsewhere, but are unlike the widely perceived humid Holocene Megathermal reported in east China and the newly reconstructed record in the alpine Retreat Lake in Taiwan. The discrepancy may be due to a relative insensitivity to humidity changes in these two areas since they have both been under the total influence of the summer monsoon. On the other hand, much enhanced evaporation over higher monsoon precipitation at Lake Yanhaizi reduces the effective humidity in the warm climate near the northern boundary of the summer monsoon. This also accounts for the fact the high-temperature Holocene Megathermal, as revealed in the Okinawa Trough and the northern South China Sea, is correlated to the dry phases at Lake Yanhaizi. Conversely, the 4-2-kyr BP coldest period in the Holocene corresponds to a wet phase at Lake Yanhaizi. (C) 2003 Elsevier Science B.V. All rights reserved.