16ka以来青海湖湖相自生碳酸盐沉积记录的古气候  

A 16000-Year Paleoclimatic Record Derived from Authigenetic Carbonate of Lacustrine Sediment in Qinghai Lake

作　　者：刘兴起[1] 沈吉[1] 王苏民[1] 张恩楼[1] 蔡元峰[2] 

机构地区：[1]中国科学院南京地理与湖泊研究所,南京210008 [2]南京大学地球科学系,南京210093

出　　处：《高校地质学报》2003年第1期38-46,共9页Geological Journal of China Universities

基　　金：国家自然科学基金 (批准号 :40 0 72 0 5 6);中国科学院创新工程 (KZCX1 10 0 1);中国博士后基金;中国科学院南京地理与湖泊研究所湖泊沉积与环境重点实验室基金资助项目

摘　　要：研究了青海湖沉积物碳酸盐的组成、来源及其同湖水物理化学性质的关系 ,建立了文石饱和指数同温度和湖水Mg/Ca比值 (可指示盐度 )的关系 ,利用碳酸盐的组成探讨了青海湖 16kaB .P .以来的古气候环境演化过程。结果表明 ,青海湖沉积碳酸盐大都是自生的 ,16kaB .P .以来沉积碳酸盐以文石为主。文石的高含量时段同暖湿气候相对应 ,低含量则同冷干气候相对应。 15 .2kaB .P .为末次冰期盛冰阶进入晚冰期的界限 ,晚冰期气候的冷暖波动频繁 ,幅度较小 ,13.4～ 13kaB .P .,11.6～ 12kaB .P .和 11～ 10 .4kaB .P .之间的冷颤动分别相当于老仙女木、中仙女木和新仙女木事件 ,12～ 13kaB .P .和 11.6～ 11kaB .P .之间的暖期则分别对应于博令和阿勒罗得暖期。全新世初期 (10 .4～ 10kaB .P .)白云石含量的突然增高和文石的消失 ,可能同淡水快速补给前期盐度较高的湖水有关 ,反映了全新世开始时气温和降水的增加具有突变性的特点。全新世大暖期的鼎盛期 ,即 6.7kaB .P .左右时湖水的盐度较低。 6.7～ 4kaB .P .为气候转型过程中的冷暖和干湿的快速波动期。 4kaB .P .以后碳酸盐含量急剧降低 。The compositions and sources of carbonates and their relation to the physical and chemical characteristics of lake waters for Qinghai Lake were studied; the relationship between the saturation index of aragonite and temperature, Mg/Ca ratio was established; and the paleoclimatic evolution of Qinghai Lake since 16 ka B.P. was discussed. The results indicate that the carbonates in the sediments of Qinghai Lake are mostly authigenetic and are mainly composed of aragonite since 16 ka B.P.. The stage of high aragonite content reflects warm-humid climate, while that of low aragonite content reflects the cold-dry climate. The Paleoclimate and Paleoenvironment of Qinghai Lake since 16 ka B.P. recorded by carbonates are as follows: The boundary between the Last Glacial and the Lateglacial is at 15.2 ka B.P.. During the Lateglacial, the climate fluctuated frequently, but with small amplitude. Three cold events in the periods of 13.4～13 ka B.P., 11.6～12 ka B.P. and 11～10.4 ka B.P. correspond to the Oldest Dryas, Older Dryas and Younger Dryas event, respectively, whereas the two warm periods between them, 12～13 ka B.P. and 11.6～11 ka B.P., correspond to Blling and Allerd period, respectively. During the early stage of the Holocene (from 10.4 ka B.P. to 10 ka B.P.), the aragonite disappeared and much dolomite emerged, which may be related to more fresh water flowage into the saline lake. This indicates that the temperature and rainfall increased abruptly in the early Holocene. The Holocene warm climatic optimum culminated at 6.7 ka B.P. when the salinity of lake water was lower. The climate fluctuated fast as it turned from warm to cold and from humid to dry between 6.7 ka B.P. and 4 ka B.P.. The climate tended to be cold and dry since 4 ka B.P..

关 键 词：沉积记录 青海湖 碳酸盐 文石 Mg/Ca比 古气候环境 沉积作用 

分 类 号：P532[天文地球—古生物学与地层学] P588.245[天文地球—地质学]