内蒙古、冲绳海槽和中国南海末次冰期盛冰期以来古气候记录  

PALEOCLIMATIC RECORDS OF INNER MONGOLIA,THE OKINAWA TROUGH AND THE SOUTH CHINA SEA SINCE THE LAST GIACIAL MAXIMUM

作　　者：陈镇东[1] 兰信企 陈延成[2] 

机构地区：[1]台湾中山大学海洋地质及化学研究所 [2]化学矿产地质研究院

出　　处：《化工矿产地质》2001年第1期39-48,共10页Geology of Chemical Minerals

基　　金：国家"九五"科学技术攻关项目 (969110 10 5专题 )

摘　　要：来自东亚夏季风北界内蒙古一个盐湖的岩心沉积物内发现粗粒沉积物 ,既可沉积在湖泊收缩期 ,也可以沉积在沙丘再次活动时期。这些沉积物有机磷含量低而碎屑组分高 ,说明它沉积在一种干旱的环境中 ;反之 ,有机质含量高而碎屑组分低的细粒沉积物则最终沉积在高湖面期 ,这是因为砂坪呈围迁状态及风成尘埃较好地保存于水体中。所揭示的三个湿期分别是 13.4～ 8kaBP、6 .4～ 5 .8kaBP和4.2～ 3.1kaBP ,第一期最湿 ,其次是第三期、第二期。上述干和湿期自始至终和早先发现的同一个干旱和半干旱转换带一致 ,但是 ,这和中国大陆东部、台湾岛、冲绳海槽和中国南海所揭示的湿润的全新世大暖期不一样 ,而且 ,全新世最冷期 (4～ 2kaBP)则对应内蒙古的一个湿期 (即 4.2～ 3.1kaBP) ,这些差别可能是由于高蒸发量远远地超过了较高的季风降水量 ,这是确定夏季风北界在该地区有效湿度的一个关键标志。A sediment core was collected from a saline lake located near the northem limit of the East Asian Summer Monsoon in Inner Mongolia.It was found that coarse sediments had been deposited either during the shrinkage phase of the lake,or during the period when the sand dune had reactivated.these sediments had low organic carbon contents and high maturity indices,indicating that they had been deposited in an arid environment. On the other hand,fine sediments with high organic contents and low maturity indices had evidently been deposited during periods of high lake stand due to the peripheral migration of the sand-flat and the better preservation of the wind-carried dusts in the water body.three humid phases ,manyly 13.4-8.0,6.4-5.8 and 4.2-3.1 kyr B.P,were recovered,with the first the wettest,followed by the third phase,the next wettest. The above dry and wet phases are consistent with those previously recovered from the same arid semi-arid transition zone.they are,however,not consistent with the humid Holocene Optimum revealed in east China,in Taiwan,in the Okinawa Trough and in the South China Sea.Furuher,the 4-2kyr B.P.coldest period in the Holocene corresponds to a wet phase in Inner Mongolia(i.e.4.2-2.1kyr B.P.)these differences may be explained by enhanced evaporation over higher monsoon precipitation.This is the key factor in determining the effective humidity in the region near the northem biundary of the summer monsoon..

关 键 词：古气候 内蒙古 冲绳海槽 中国 南海 冰川 末冰冰期 降水量 

分 类 号：P532[天文地球—古生物学与地层学]