唐古拉山地区第四纪冰川作用与冰川特征

自中更新世以来,唐古拉山地区发生过3次更新世冰川作用(即昆仑冰期、倒数第二次冰期和末次错冰期)和2次全新世晚期冰进(即新冰期和小冰期冰进).昆仑冰期(最大冰期)发生在中更新世早期(0.80～0.60MaBP),不仅是本区最早的一次冰期,而且也是冰川规模最大的一次冰期,当时的冰川规模比现代冰川大16～18倍;倒数第二次冰期发生在中更新世晚期(0.30～0.135MaBP),比现代冰川大13～15倍;末次冰期发生在晚更新世晚期,应分为末次冰期早冰阶(75.0～58.0kaBP)和晚冰阶(32.0～15.0kaBP,23.0kaBP时达到极盛),但在唐古拉山地区截止目前还未找到早冰阶的冰川遗迹,因此,只对末次冰期的晚冰阶(LMG)进行了探讨.LMG时,冰川规模比现代冰川大10倍;新冰期发生在全新世高温期后,冰碛物的¹⁴C测年为(3540±160)aBP,冰川规模略大于现代冰川;小冰期发生在15～1世纪,冰川规模已接近于现代冰川.由于青藏高原的上升,对高原腹部地区引起的干旱化过程和水分严重不足,使唐古拉山地区的冰川自昆仑冰期以来,冰川规模一次比一次明显的减小.

The Quaternary Gl aciations and Glacier Properties in the Tanggula Range

The occurrence and development of the Quaternary glaciers in the Tanggula Range was closely related to the amplitude and time of mountain uplift and climatic conditions. The evolution process of the glaciers in the range did not completely accord with that in other regions of the Tibetan Plateau, and the number of glaciations was not completely the same. Since the mid-Pleistocene epoch, three Pleistocene glaciations (i.e., the Kunlun Ice Age, the Penultimate Ice Age and Last Ice Age) and two two Holocene glaciations (i.e., the Neoglaciation and the Little Ice Age) have occurred in the Tanggula Range. The Kunlun Ice Age occurred in the early mid-Pleistocene epoch (0.80～0.60 Ma BP), which was not only the earliest ice age, but also the largest glaciation in this range. The glaciers developed over the main ridge connected together, forming a huge ice cap with piedmont glaciers, of which the size was 16～18 times larger than that at present. The Penultimate Ice Age occurred in the late mid-Pleistocene (0.30～0.135 Ma BP), when the size of glaciers, still large ice cap with piedmont glaciers, was smaller than that in the preceding ice age but was 13～15 times larger than that at present. The Last Ice Age occurred in the late period of the late Pleistocene, which can be divided into the earlier ice age (75.0～58.0 ka BP) and the latter ice age (32.0～15.0 ka BP, with the largest scale of glaciers during 23.0～16.0 ka BP). Up to now, however, the glacial vestiges of the earlier ice age have not been found in field investigation and in the research of the Quaternary glaciers yet. Therefore, this paper discusses the latter ice age of the Last Ice Age (i.e., Last Glacial Maximum) only. During the latter ice age of the Last Ice Age, the scale of glaciers, mainly in the form of ice cap and valley glaciers, was 10 times larger than that at present. The Neoglaciation occurred after the high-temperature period of the Holocene epoch ( ¹⁴C dating (5805±173) a BP), when the ¹⁴C age was (3540±160) a BP, and the scale of glaciers was slightly larger than that at present. The Little Ice Age occurred during the 1500 s～1800 s, and the scale of glaciers was close to that at present;The scale of glaciers in the Tanggula Range has become smaller and smaller since the Kunlun Ice Age, because of the drying process in the hinterland of the Tibetan Plateau due to the uplift of the plateau. The evolution course of glacial climate type was monsoon maritime →transitional monsoon maritime-continental→monsoon continental→continental.