摘要
班公错以东的塔古图穷地质剖面的样品中,分析出6属15种介形类。就介形类化石组合特征及其古生态以及^(14)C测年资料分析表明,晚更新世晚期此区湖泊发生了明显的变化。在距今40 000—35 000年前,本区为有河流注入的缓慢流动的淡水湖,水温大体与现代接近。在距今35 000—25000年前,由于气候趋于干冷,入湖迳流减少,湖泊相对平静些。在整个剖面所代表的沉积时期,曾出现数次湖水变浅和水体中眼子菜繁茂期,除距今35 000年前左右,在其它数次湖水变浅期,湖水水质可能稍有变化。
Twenty-two samples with ostracodes were collected from a natural exposure of late Pleistocene lacustrine deposits nearby Tagutuqiong, east of Bangong Lake. Fifteen species belonging to 6 genera have been identified. According to their distribution within the strata, three ostracode assemblages are distinguished as follows:1. Ilyocypris-Leucocythere Assemblage; 2. Leucocythere positilirata-L. tropis Assemblage; 3. Limnocythere dubiosa Assemblage, in which other species are very rare.Based on the palaeoecologic ostracodes and ~14C dating, palaeogeographic changes between 40 000 yrs. BP and 25 000 yrs. BP in this area are recognized. From 40 000yrs. BP to 35 000 yrs. BP the lake, with nourished by rivers was a fresh-water lake, with temperature similar to that of the present day. Then the lake became drier, decreasing in temperature, with less water input from rivers, which became stable between 35 000 yrs. BP and 25 000 yrs. BP. The water-level of the lake might have been dropped down several times to allow the rapid growth of Potamogeton distinctus A. Bennett in the lake water from 40 000 yrs. BP to 25 000 yrs. BP, and the features of the lake water might have been coordinately changed.
出处
《微体古生物学报》
CSCD
北大核心
1991年第1期57-64,129,共8页
Acta Micropalaeontologica Sinica
基金
国家自然科学基金
