高级检索

    青藏高原唐古拉山口第四纪冰碛层划分及其地质环境意义

    Quaternary tills at the pass of the Tanggula Mountains on the Qinghai-Tibet Plateau and their geological-environmental significance

    • 摘要: 提要:在对唐古拉山口现代冰川和古冰川考察研究的基础上,结合定位观测资料和TL、10B-26Al-21Ne及 14C 测年数据,对区内第四纪冰川遗迹进行了深入讨论,划分出二次冰期(即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)和二次全新世冰进(即新冰期和小冰期)。提出在早更新世时,由于山体未达到当时冰川发育的雪线高度,所以未发育冰川。但在唐古拉山口地区,截止目前还未找到中更新世早期的倒数第三次冰期的冰川遗迹,由于高原隆升的滞后性和冰川发育的延滞效应及“亚洲干极”的耦合,推测仍只发育局部冰川作用。进一步研究表明,古今雪线由高原边缘向腹地升高,唐古拉山地区高出边缘1 500 m 左右,生动表现了“亚洲干极”的作用;广泛分布的湖群说明羌塘地区是一个大江大河尚未伸入的内流地区,意味着青藏高原是个年青的高原。由于青藏高原的隆升,对高原腹地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倒数第二次冰期以来,冰川规模一次比一次明显地减小。

       

      Abstract: Abstract:Based on investigations and studies of modern and ancient glaciers at the Tanggula Mountain pass, coupled with the GPS data and TL, 10B-26Al-21Ne and 14C dating data, Quaternary remnants of glaciation in the study area are discussed in detail. Two glacial epochs (i.e., the late Middle Pleistocene penultimate glacial epoch and the mid-late Late Pleistocene last glacial epoch) and two Holocene glacial advances (i. e. the Neoglaciation and the Little Ice Age) have been intensively studied. The mountains had not reached the height of the snowlines in the early Pleistocene; so glaciers did not develop then. However, in the area the Tanggula pass the remnants of the early Middle Pleistocene third glaciation from the last have not been found because of the lag effects of Tibetan Plateau uplift and development of glaciers and their coupling of the Dry Pole of Asia. The authors infer that only local glaciation has developed. Further study indicates that the ancient and present snowlines have risen from the margins of the Qinghai-Tibet Plateau to the interior and the Tanggula Mountains area is ~1500 m higher than the the margins, which vividly reflects the role of the Dry Pole of Asia, as suggested by some scientists earlier. The wide distribution of lake swarms shows that the Qiangtang area is an interior drainage area into which big rivers have not yet stretched, implying that the Qinghai-Tibetan Plateau is younger. The scale of glaciers in the Tanggula Range has become smaller and smaller since the penultimate glacial epoch because of the drying process and severe shortages of moisture in the interior of the plateau due to the uplift of the plateau.

       

    /

    返回文章
    返回