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青海湖北岸刚察县城东与泉吉乡西发现原生砂楔群,楔内充填物均为中细粒砂,楔体底部中细粒砂ESR测年数据表明,刚察县城东3个原生砂楔发育时代分别为(774±70)ka、(773±70)ka和(229±20)ka,泉吉乡西1个原生砂楔形成时代为(197±18)ka,反映该区至少发育两期原生砂楔,其形成时代分别对应昆仑冰期和倒数第二次冰期.基于原生砂楔的特殊形成环境,估算青海湖盆地在昆仑冰期早期的年均温不高于-7.5~-10℃,比现今至少低9.2~11.7℃,中更新世早期青海湖盆地发育多年冻土,青藏高原东北部可能已经进入冰冻圈;倒数第二次冰期的年均温不高于-9.5~-10℃,比现今低11℃以上.
Primary sand wedge group and wedge filling are found in the east and spring of Jiqing Township in the north bank of Qinghai Lake. Both of them are medium and fine grained sand. ESR dating of fine grained sand in the bottom of the wedge shows that there are 3 primary The era of sand wedge development was (774 ± 70) ka, (773 ± 70) ka and (229 ± 20) ka, respectively. The formation time of a primary sand wedge in the west of Quanjixiang was (197 ± 18) ka, Based on the special forming environment of primary sand wedge, the average annual temperature of Qinghai Lake basin in Kunlun glacial period is not higher than -7.5 ~ -10 ℃, which is at least 9.2 ~ 11.7 ℃ lower than today. Permafrost in Qinghai Lake basin developed in the early mid-Pleistocene and the northeastern Qinghai-Tibet Plateau may have entered the cryosphere. The average annual temperature of the penultimate glaciation is not higher than -9.5 ~ -10 ℃, 11 ℃ lower than today’s.