青藏高原东部雀儿山地区新近纪隆升速率探讨——来自雀儿山花岗岩体磷灰石裂变径迹证据

An approach to the Neogene uplift rates for the eastern Qinghai-Xizang Plateau: Evidence from the fission track ages of the apatite from the Chola granites in western Sichuan

关键词:  青藏高原东缘  雀儿山花岗岩  磷灰石裂变径迹年龄  隆升速率

Key words:  eastern Qinghai-Xizang Plateau  Chola granite  apatite fission track age  uplift rate

摘要:

通过青藏高原东部川西地区雀儿山花岗岩体磷灰石裂变径迹分析，新获得了4个磷灰石裂变径迹年龄值，分别为4.9 ±0.3Ma、6.2 ±0.5 Ma、7.2 ±0.4 Ma和7.3 ±0.7 Ma。运用径迹年龄-地形高差法计算出雀儿山花岗岩体新近纪的隆升速率，为0.15~2 mm/a，平均隆升速率为0.78mm/a。隆升速率在每个阶段有所不同，但呈现出一种快速隆升→缓慢隆升的过程，为整个青藏高原东缘的隆升过程提供了约束条件。

Abstract:

The fission-track analysis is made for the apatite from the Chola granites in western Sichuan in the eastern part of the Qinghai-Xizang Plateau, and gives four fission track ages:4.9 ±0.3 Ma, 6.2 ±0.5 Ma, 7.2 ±0.4 Ma and 7.3 ±0.7 Ma, which have disclosed that the Chola Mountains began to uplift at ca. 7.3 Ma BP. With the aid of fission-track analysis-elevation method, the uplift rates of the Chola Mountains are calculated as 0.15-2 mm/a, with an average of 0.78 mm/a since the Miocene. On the whole, the uplifting of the Chola Mountains displays the evolutionary processes from the rapid uplift to the slow uplift. The results of research in this study may be helpful to the study of the uplift of the eastern Qinghai-Xizang Plateau.