地理学报 ›› 2018, Vol. 73 ›› Issue (5): 957-972.doi: 10.11821/dlxb201805014

• 地表过程 • 上一篇    下一篇

新疆阿尔泰山东段冰碛物光释光测年研究

贾彬彬1(),周亚利1(),赵军2   

  1. 1. 陕西师范大学地理科学与旅游学院,西安 710062
    2. 中国人民武装警察部队黄金第八支队,乌鲁木齐 830057
  • 收稿日期:2017-06-26 出版日期:2018-05-03 发布日期:2018-05-03
  • 基金资助:
    国家自然科学基金项目(41371029);中国博士后特别资助项目(2012T50795);中国博士后基金项目(2011M501443)

Optically stimulated luminescence dating of moraines in East Altay Mountains, Xinjiang

JIA Binbin1(),ZHOU Yali1(),ZHAO Jun2   

  1. 1. School of Geography and Tourism, Shaanxi Normal University, Xi'an 710062, China
    2. No.8 Gold Geological Party, CPAPF, Xinjiang, Urumqi 830057, China
  • Received:2017-06-26 Online:2018-05-03 Published:2018-05-03
  • Supported by:
    National Natural Science Foundation of China, No.41371029;China Postdoctoral Science Foundation, No.2012T50795;China Postdoctoral Fund Project, No.2011M501443

摘要:

冰川是塑造地表形态最积极的外营力之一,对冰川地貌的年代学研究是重建古冰川发展史的关键,也是研究气候变化的重要途径。冰碛物是冰川作用的直接产物,代表过去发生的冰川事件,对冰碛物进行准确测年能够为重建古冰川的进退、理解区域古气候变化提供年代学支撑。本文在新疆阿尔泰山东段采集了8个冰碛物样品以进行光释光测年,利用单片再生剂量法对90~125 μm的石英颗粒进行等效剂量的测定。通过等效剂量值频率分布特征及De(t)坪区图分析得出大部分冰碛物的光释光信号晒退不彻底,所以利用一阶动力学公式对持续激发的光释光信号晒退曲线(CW-OSL)进行多组分拟合拆分,得到快速、中速、慢速3种组分,依据分离出的快速组分确定等效剂量值。研究结果显示,距今32 ka以来阿尔泰山东段区域在MIS3阶段、MIS2阶段、8.2 ka左右、全新世大暖期及新冰期等5个时段有冰川发育,冰川发育与气候变化密切相关。

关键词: 阿尔泰山, 冰碛物, 光释光测年, 冰川作用

Abstract:

The glacier is one of the most positive external forces for shaping the landscape of earth surface in alpine region. The geochronology study of glacial stratigraphy can provide insightful information about the ancient glacier process, which is sensitive to climate change. Compared to the sediments of ice lake and ice water terrace with complex material source, moraine is the direct product of glacial movement. Consequently, it can also reflect the glacier events that occurred in the past. The accurate dating of moraine can provide chronology evidence for improving the understanding of reconstruction of climate change patterns. The Altay Mountains is one of the major mountain ranges for understanding Quaternary glaciation in northwestern China. Most of the studies have focused on western Altay Mountains, Xinjiang. However, the chronology of the moraines in its eastern section is not well studied. In this study, OSL dating technique method was applied to determine the ages of the glacial moraine deposits of coarse grained quartz (90-125 μm) in the East Altay Mountains. According to analysis of the frequency distribution of De value and De(t) plots, most of the moraine samples showed partial bleaching. Therefore, the first-order kinetic equation was used to separate the CW-OSL curve into three component exponentials (fast, medium and slow components) and the fast components were used to determine these equivalent doses. The OSL dating results of moraines in East Altay Mountains deposited seperately in 32.33 ka, 16.07 ka, 8.41-8.07 ka, 6.83-6.48 ka and 4.62 ka. This implied that the glacier development process was identified with MIS3, MIS2, 8.2 ka Cold Events, Holocene Optimum and Neoglaciation, respectively. Observably, moraine can occur with glacial advance or recession during the warm or cold climate episodes, while the development of glaciers in the Altay Mountains was closely related to global climate change. This study demonstrates the successful application of quartz OSL with fast component signal to glacial sediments from the Altay Mountains. Furthermore, it can complement the geochronology data for moraine sedimentary records to reveal the glacier evolution history in the whole Altay Mountains region since 32 ka BP.

Key words: Altay Mountains, moraines, OSL dating, glacial movement