东南极拉斯曼丘陵中晚全新世湖泊生物量的变化记录

A MID-TO LATE-HOLOCENE LAKE BIOMASS RECORD IN THE LARSEMANN HILLS,EAST ANTARCTICA

对东南极拉斯曼丘陵莫愁湖ZH沉积柱进行了生态地质学的研究,通过AMS14C定年构建年龄框架,采用550℃烧失量、粒度和元素地球化学指标等,恢复了中晚全新世该地区较高分辨率的湖泊生物量记录。结果显示,6 600—6100 cal.a BP、5 400—4 800 cal.a BP、4 650—3 750 cal.a BP和3 500—2 850 cal.a BP为莫愁湖生物量高值期,气候相对温暖适宜,湖泊生产力旺盛;6 100—5 400 cal.a BP、4 800—4 650 cal.a BP,4 400—4 300 cal.a BP和3 750—3 500cal.a BP为湖泊生物量低值期,气候相对寒冷,湖泊生产力相对较弱。而且在整体较暖的气候环境下,出现了其他无冰区沉积物中鲜有记录的4 800—4 650 cal.a BP、4 400 cal.a BP前后和3 750—3 500 cal.a BP的气候快速变冷事件。根据莫愁湖湖泊生物量恢复的东南极拉斯曼地区高分辨的气候变化特征,与太阳活动强度和东南极大陆冰芯记录相吻合,为东南极中晚全新世多样的气候格局研究提供了新的依据。

Using the geochemical analysis of lake sediment core ZH, retrieved from Mochou Lake, Larsemann Hills （69~ 22.3＇S, 76~22.0＇E） , East Antarctica, a climate chronology was established on the basis of AMSI4C dating, stretc- hing from 6 600--1 900 cal. a BP. The high resolution records of lake biomass were retrieved from the loss on igni- tion at 550~C （ LOI550~c ） , grain size and geochemical element indexes. The results showed high biomass periods at 6 600--6 100 cal. a BP, 5 400---4 800 cal. a BP, 4 650--3 750 cal. a BP and 3 500--2 850 cal. a BP, which were consistent with periods of warm and humid climate and high lake productivity. Brief but pronounced low bio- mass periods occurred at about 6 100--5 400 cal. a BP, 4 800--4 650 cal. a BP, 4 400 cal. a BP and 3 750-- 3 500 cal. a BP, associated with cold and arid climate, as well as low lake productivity. Some of the rapid cooling events identified have rarely been reported from other ice-free regions of East Antarctica. Overall, the biomass of Mochou Lake provided high resolution data on the climate characteristics of the Larsemann Hills and new informa- tion on the climate pattern of the mid- to late-Holocene in East Antarctica.