西藏台错古湖晚第四纪轮藻类及其生态环境、气候变化探讨  

STUDY ON THE LATE QUATERNARY CHAROPHYTES,ECOLOGICAL ENVIRONMENT AND CLIMATE AT PALEOLAKE TAICUO,TIBET

作　　者：刘俊英[1,2,3] 王海雷[1,2,4] 

机构地区：[1]国土资源部盐湖资源与环境重点实验室,北京100037 [2]中国地质科学院盐湖与热水资源研究中心,北京100037 [3]中国地质科学院地质研究所,北京100037 [4]中国地质科学院矿产资源研究所,北京100037

出　　处：《微体古生物学报》2011年第3期261-283,共23页Acta Micropalaeontologica Sinica

基　　金：国家自然科学基金重点项目(编号40531002);国家大地调项目(121201081805;1212010818057)资助成果

摘　　要：西藏台错TT-1剖面厚369 cm,为一套碳酸盐粘土和粘土碳酸盐沉积,地层测年为41.4—4.5 ka,含丰富的轮藻化石,分属于11个轮藻植物群,群落所在地层的碳酸盐和钙质含量分别为80%和33%。从老到新(剖面自下而上):①41.4—26.64 ka(369—319 cm),处于末次冰期间冰阶MIS3a暖期,湖区气候暖湿,湖泊水深,水体动荡,水中碳酸盐和钙质含量较低(分别为13%—21%和4.4%—6.6%),无轮藻生存。②26.64—20.48 ka(319—284cm),轮藻群落非常繁盛,尤其在25.20—22.45 ka(319—301 cm)时段,水草丛生,水体钙质和有机碳含量较前一时期高,水温较高,生产力旺盛,反映湖区气候仍较暖湿,大致在22 ka时,湖区气候暖湿度和湖水温度已趋向干冷。③20.48—14.60 ka(284—217 cm)轮藻植物群不甚繁盛,湖区气候干冷,湖水温度低,营养元素缺乏,轮藻生产力降低幅度大,全球末次冰盛期(Last Glacial Maximum)气候在湖区呈现。④14.60—10.40 ka(217—125 cm)轮藻植物群重新繁盛起来,但是藏卵器在各时段产量并不衡定,湖区生态环境气候多变,湖水温度时高时低。在13.62—12.35 ka前后,气候较暖湿,湖泊水温较高,营养元素和氧气较充足,轮藻较茂盛。在晚期受全球新仙女木事件(Younger Dryas)影响,生产力减退。⑤10.43—4.5 ka(125—0 cm)湖区气候仍偏暖湿,轮藻群落较繁盛,晚期(6.20—4.5 ka)环境湿度增大,湖泊水温升高,轮藻繁盛状况更好,生产力达剖面第二位。The section TT-1 at Taicuo,Tibet is 369 cm of carbonate-bearing clay and clay-bearing carbonate sequence,aged 41.4-4.5 ka,rich in fossil charophyte which can be subdivided into 11 floras.Five palaeoenvironmental development stages of the palaeolake Taicuo can be recognized.（1） 41.4-26.64 ka（369-319 cm）,a warm period in MIS 3a,when the climate was warm and wet,the water was deep and unrest,with lower contents of carbonate and calcium（13%-21% and 4.4%-6.6%）,and no charophytes existed.（2） 26.64-20.48 ka（319-284 cm）,a flourishing period of the floras,when water plants were lush,and the water had a higher content of calcium and organic carbon,especially during 25.20-22.45 ka（319-301 cm）.The climate was still warm and wet,after about 22 ka.However,the climate tended to be cold and dry,and the water temperarure was going down.（3）20.48-14.60 ka（284-217 cm）,the charophytes were less flourishing as the climate became colder and drier,which caused by the decline of water temperature and nutrients.All this was a reflection of the global LMG climate in the lake.（4） 14.60-10.40 ka（217-125 cm）,the charophytes got flourishing again,but the climate was variable in the lake resulted in the frequent water temperature fluctuation.As a result,there was also an inconstant amount of gyrogonites produced.In the period of 13.62-12.35 ka,as it turned comparatively warm and wet and the water temperature went up,the charophytes got quite lush with adequate nutrients and oxygen.But the reproduction of the floras declined later during the Younger Dryas period.（5） 10.43-4.5 ka（125-0 cm）,the climate in the lake tended to be warm and wet,and the charophytes were in a well-growing state.The charophytes became more thriving during 6.20-4.5 ka as the environmental humidity got higher and the water temperature increased,and the floras reproduction ranks the second in the section.

关 键 词：轮藻类 生态环境 晚第四纪 台错古湖 西藏 

分 类 号：Q914[天文地球—古生物学与地层学]