青藏高原当雄错晚更新世末期-全新世早期叠层石新发现

 在青藏高原首次发现当雄错第四纪晚期叠层石群，其发现对于阐明高原第四纪晚期古环境演化有重要意义。通过对当雄错第四纪晚期发育的3层叠层石的地球化学特征以及14C年龄研究发现：叠层石发育最佳温度20~30℃，当温度低于12~15℃时，蓝藻停止生长。目前，当雄错湖水年均温度为4.8℃，可知当时水温高于现代10℃；这3层叠层石的¹⁴C年龄分别与同布林（Bölling）和阿路罗德（Allevöd）两次暖期事件，及10.5 ka~9 kaBP全新世早期转暖期一致，并且叠层石中δ¹⁸O均值在-7.23~-6.6之间，δ¹³C均值在4.75~5.65之间，两者均较高，可知当雄错当时气温较高。该时段3个暖期的发现，对详细建立划分青藏高原第四纪晚期气候-年代学标尺有重要价值。

New discovery of Late Pleistocene-Early Holocene stromatolites in Damxung Co,Qinghai-Tibet Plateau

The Late Quaternary stromatolite assemblages at Damxung Co have been found on the Qinghai-Tibet Plateau for the first time. The discovery has great significance for elucidation of the paleoenvironmental evolution on the plateau in the Late Quaternary. Geochemical characteristics and 14C ages of these three layers stromatolites are studied in this paper. The result shows that the optimum temperatures for stromatolite growth are 20℃ to 30℃, and that when the temperature is lower than 15℃, the growth of blue algae will stop. At present, the annual mean temperature of lake water is 4.8℃, suggesting that the water temperature then was 10℃ higher than the modern times temperature. The result also shows that 14C ages of these three layer stromatolites are consistent with Bölling, Allevöd and early Holocene warm period events, with mean values of δ¹⁸O and δ¹³C being high in these three layer stromatolites, i.e., -7.23 to -6.6 and 4.75 to 5.65, respectively, suggesting that the air temperature was high. The discovery of three warm stages in this period is of vital value for the establishment of the Late Quaternary climatic-chronological scale of the Qinghai-Tibet.