地理学报 ›› 2019, Vol. 74 ›› Issue (7): 1345-1362.doi: 10.11821/dlxb201907006

• 气候变化与地表过程 • 上一篇    下一篇

藏南羊卓雍错沉积物元素地球化学记录的过去2000年环境变化

郭超1,2,蒙红卫3,马玉贞1(),李丹丹1,胡彩莉1,刘杰瑞1,雒聪文1,王凯1   

  1. 1.北京师范大学地理科学学部 地表过程与资源生态国家重点实验室,北京 100875
    2.湖北文理学院资源环境与旅游学院,襄阳 441053
    3.云南师范大学旅游与地理科学学院,昆明 650500
  • 收稿日期:2018-01-24 修回日期:2019-03-11 出版日期:2019-07-25 发布日期:2019-07-23
  • 通讯作者: 马玉贞 E-mail:mayzh@bnu.edu.cn
  • 作者简介:郭超(1988-), 男, 陕西人, 博士, 主要从事环境演变、孢粉学、元素地球化学等方面研究。E-mail: gc@mail.bnu.edu.cn
  • 基金资助:
    国家重点基础研究发展规划(973项目)(2013CB956001);国家自然科学基金项目(41571186);国家自然科学基金项目(41330748)

Environmental variations recorded by chemical element in the sediments of Lake Yamzhog Yumco on the southern Tibetan Plateau over the past 2000 years

GUO Chao1,2,MENG Hongwei3,MA Yuzhen1(),LI Dandan1,HU Caili1,LIU Jierui1,LUO Congwen1,WANG Kai1   

  1. 1.State Key Laboratory of Earth Surface Processes and Resource Ecology, Faculty of Geographical Science, Beijing Normal University, Beijing 100875, China
    2.College of Resource Environment and Tourism, Hubei University of Arts and Science, Xiangyang 441053, Hubei, China
    3.School of Tourism and Geographical Sciences, Yunnan Normal University, Kunming 650500, China
  • Received:2018-01-24 Revised:2019-03-11 Online:2019-07-25 Published:2019-07-23
  • Contact: MA Yuzhen E-mail:mayzh@bnu.edu.cn
  • Supported by:
    The National Basic Research Program of China(2013CB956001);National Natural Science Foundation of China(41571186);National Natural Science Foundation of China(41330748)

摘要:

以青藏高原南部的羊卓雍错(简称羊湖)沉积岩芯为研究对象,以较可靠的年代数据( 210Pb和AMS 14C交叉定年)为框架,基于高分辨率的元素地球化学记录,通过数理统计分析方法提取环境信息,结合粒度和磁化率,重建该地区过去2000年来的环境变化。结果显示,该区黑暗时代冷期(DCAP)和小冰期(LIA)气候较为寒冷,降水量较高;而中世纪暖期(MWP)和现代暖期(CWP)气候较为温暖,降水量较低,气候具有冷湿—暖干的特征。其中,重建的温度显示,中世纪暖期的温暖程度似乎持平甚至超过20世纪暖期;小冰期期间可能存在一次百年尺度的温暖事件,而17世纪和18世纪可能是过去2000中最寒冷的一段时期。分析发现,过去2000年以来青藏高原南部存在着冷湿—暖干的气候模式;过去2000年青藏高原南部地区温度的变化可能主要受到太阳辐射的影响,而小冰期期间西风环流的南移和增强可能是导致区域降水增加的重要因素。另外,该时期羊湖的湖泊水位的变化受温度和降水共同控制:当温度降低,降水增加时,湖泊水位上升,反之亦然。

关键词: 元素地球化学, 青藏高原南部, 过去2000年, 中世纪暖期, 小冰期, 环境变化

Abstract:

The Tibetan Plateau is sensitive to climate changes induced by interactions of large scale atmospheric circulations, including the East Asian monsoon, Indian monsoon and mid-latitude westerlies. In this paper, we present a high-resolution chemical element dataset covering the past 2000 years from Lake Yamzhog Yumco (28°27′N-29°12′N, 90°08′E-91°45′E, altitude in 4440 m a.s.l.), which is a representative inland lake located in the southern Tibetan Plateau. These data were acquired using an X-ray fluorescence (XRF) core scanner, which is used for in situ, high-resolution, continuous, multi-element analyses. The chronology presented herein is based on 210Pb and AMS 14C dates from the macro-remains of plants. The interpretation of elemental geochemistry, together with magnetic susceptibility and grain-size, enabled the reconstruction of the environmental changes in the southern Tibetan Plateau over the past 2000 years. Reconstructions of the temperatures, precipitation and lake levels indicated that the Medieval Warm Period (MWP) and Current Warm Period (CWP) were associated with low precipitation and high temperatures. In contrast, the Dark Cold Age Period (DCAP) and Little Ice Age (LIA) were associated with high precipitation and low temperatures. Moreover, the level of warmth during the peak of the MWP may equal or slightly exceed the 20th century warming. In addition, the prolonged LIA may have experienced a warm event on a centennial timescale, and the 17th and 18th centuries may be the coldest centuries in the last two millennia. Our reconstructions also indicated that the lake level evolution has been affected by interactions of temperature and precipitation. More specifically, during the cold periods, an increase of precipitation amplified the rise of lake levels, and vice versa. The climate records from Lake Yamzhog Yumco have confirmed a cold-moist/warm-dry climate pattern on the southern Tibetan Plateau over the past 2000 years. Additionally, the temperature variations inferred from the records were strongly correlated with the solar irradiance and northern hemispheric temperature changes, which suggests a possible link between the solar forcing and climate variability in the past 2000 years on the southern Tibetan Plateau. In addition, the enhancement and southward shift of the westerlies was determined to have significantly contributed to the high precipitation conditions during the LIA on the southern Tibetan Plateau.

Key words: elemental chemistry, southern Tibetan Plateau, the past 2000 years, Medieval Warm Period, Little Ice Age, climate change