唐古拉山垭口地区的第四纪冰川测年新研究

The Sequence of Quaternary Glaciations around the Tanggula Pass

在野外综合考察的基础上,对唐古拉山垭口地区末次冰期的冰碛漂砾(或有冰川擦痕的露头)进行了宇生核素10Be暴露年龄的测定,得到(16.1±1.7)ka BP、(31.9±3.4)ka BP、(41.4±4.3)kaBP和(66.8±4.3)ka BP 4个测年数据.结合前人对本地区研究和测年的资料,确定该区更新世经历了4次较大规模的冰川作用:中更新世晚期的倒数第二次冰期、晚更新世中晚期的末次冰期早冰阶、间冰阶和晚冰阶,依次与MIS6、MIS4、MIS3和MIS2阶段对应;全新世经历了2次小的冰进:新冰期和小冰期,它们的时代与青藏高原其它地区新冰期和小冰期的时代基本一致.末次盛冰期的冰川范围十分有限,并且MIS3阶段的冰进规模远远超过了末次盛冰期.早期考察中所命名的唐古拉冰期和巴斯错冰期的时代是中更新世晚期(MIS6)和末次冰期早冰阶(MIS4),扎加藏布冰期的冰碛可能是末次冰期的冰碛叠加在倒数第二次冰期的冰碛物之上,而又经过后期作用改造而形成的一套冰碛.在该区老的冰碛物上没有测定出MIS6阶段之前的年代数据,可能是由后期的破坏或采集的样品不够充分所致,因此对本区最早冰川作用的时代还有待于进一步深入研究.

Based on investigations and studies of modern and ancient glaciers around the Tanggula Pass, dating of cosmogenic radionuclide 10 Be exposure age of the last glacial moraine bounders （or striated outcrops） of this region, four data, i. e. , （16.1±1.7） ka BP, （31.9±3.4） ka BP, （41.4±4.3） ka BP and （66.8±4.3） ka BP, were gained. Combined with the former studies and dating, it is believed that the area around the Tanggula Pass has experienced four major Pleistocene Glaciations, corresponding to marine isotope stage （MIS） 2, 3, 4 and 6, respectively, and two Holocene glacial advances （the Neoglaciation and the Little Ice Age）. The dating results are consistent with those in other areas of the Tibetan Plateau. The extent of the Last Glacial Maximum was limited; however, the scale of glacial advance during MIS 3/4 even exceeded that of the Last Glacial Maximum. The Tanggula Glaciation and Basicuo Glaciation named in the early expedition are demonstrated occurring during the late Middle Pleistocene （MIS 6） and the early stage of the Last Glaciation （MIS 4）. There is no dating result older than MIS 6 in the oldest tooraines of this area, perhaps, er or insufficient of collect study of timing of the oldest should be performed. due to destruction ing samples. Further glaciation in this area