| 晚第四纪MIS6以来柴达木盆地成盐作用对冰期气候的响应 |
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| 引用本文： | 陈安东,郑绵平,宋高,王学锋,李洪普,韩光,袁文虎.晚第四纪MIS6以来柴达木盆地成盐作用对冰期气候的响应[J].地质论评,2020,66(3):611-624. |
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| 作者姓名： | 陈安东 郑绵平 宋高 王学锋 李洪普 韩光 袁文虎 |
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| 作者单位： | 1) 中国地质科学院矿产资源研究所, 自然资源部盐湖资源与环境重点实验室, 北京, 100037;2) 中国科学院地质与地球物理研究所, 新生代地质与环境重点实验室, 北京, 100029;3) 青海省柴达木综合地质矿产勘查院, 青海格尔木, 816000;3) 青海省柴达木综合地质矿产勘查院, 青海格尔木, 816099 |
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| 基金项目： | 本文为国家重点研发计划课题（编号：2017YFC0602806）、国家自然科学基金资助项目（编号：41902190）、中国地质科学院矿产资源所基本科研业务费专项经费（编号：KK1923）和中国地质调查局地质调查项目（编号：DD20190172、DD20160054）的成果。 |
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| 摘 要： | 气候是控制柴达木盆地盐类沉积的主要因素之一,但是其作用机制尚待明确。作者以柴达木盆地察汗斯拉图盐湖的3个含盐剖面为研究对象,采用多接收电感耦合等离子质谱(MC-ICP-MS)铀系测年测定其沉积时代,并通过X射线粉晶衍射(XRD)分析测定其盐类矿物种类。铀系测年显示D18剖面石盐和芒硝层的沉积时代为13.1±2.0 ka BP～15.9±2.5 ka BP,其中芒硝沉积年代属于末次冰期MIS2晚期;MXK2剖面芒硝层的沉积时代分别为131.7±39.5 ka BP和158.3±10.8 ka BP,D12剖面芒硝层的沉积时代分别为166.6±20.2 ka BP和198.0±20.6 ka BP,可以对应于倒数第二次冰期MIS6。XRD分析确定了3个剖面的盐类矿物主要为芒硝、石盐和石膏。综合多个盐湖晚第四纪成盐数据,本文认为倒数第二次冰期MIS6和末次冰期MIS2是柴达木盆地晚第四纪重要的成盐期,冰期的冷干气候有利于石盐和芒硝等盐类沉积。柴达木盆地"冰期成盐"的根本原因,是由于冰期环境下盆地周边山体冰川规模的扩张以及干冷的冰期气候,共同造成了盐湖补给水量的减少。此外,晚第四纪MIS6和MIS2的冰期降温也是导致盆地中冷相盐类沉积的直接原因。
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| 关 键 词： | 柴达木盆地 盐湖 成盐期 倒数第二次冰期 末次冰期 铀系测年 |
| 收稿时间： | 2019/10/17 0:00:00 |
| 修稿时间： | 2020/2/8 0:00:00 |
Evaporite deposits in the Qaidam Basin and their response to Quaternary glacial climates since marine oxygen isotope stage 6 (MIS6) |
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| CHEN Andong,ZHENG Mianping,SONG Gao,WANG Xuefeng,LI Hongpu,HAN Guang,YUAN Wenhu.Evaporite deposits in the Qaidam Basin and their response to Quaternary glacial climates since marine oxygen isotope stage 6 (MIS6)[J].Geological Review,2020,66(3):611-624. |
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| Authors: | CHEN Andong ZHENG Mianping SONG Gao WANG Xuefeng LI Hongpu HAN Guang YUAN Wenhu |
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| Abstract: | Objectives: Climate is one of the dominant factors which control evaporite deposits in Qaidam Basin, but its mechanism remains to be clarified. The aim of this paper is to make a comparison between the evaporite deposit period and glacial period since marine oxygen isotope stage 6 (MIS6), and clarify the role of late Quaternary glacial climate in evaporite deposit.
Methods:The authors took 3 salt- bearing profiles (D18, MXK2 and D12) from the western Qaidam Basin as the study object, applied multiple collector inductively coupled plasma mass spectrometry (MC- ICP- MS) to obtain the salt deposit age, and applied X- ray diffraction (XRD) to identify the salt minerals from the profiles.
Results: MC- ICP- MS U- series dating indicated the deposit ages of D18 profile are 13.1±2.0 ka BP~15.9±2.5 ka BP, of which the mirabilite deposit belong to the late stage of last glacial MIS2; mirabilite deposit ages in MXK2 profile are 131.7±39.5 ka BP and 158.3±10.8 ka BP respectively, mirabilite deposit ages in D12 profile are 166.6±20.2 ka BP and 198.0±20.6 ka BP, which can correspond to the penultimate glacial period MIS6. XRD analysis confirmed that salt minerals in the 3 profiles were mainly mirabilite, halite and gypsum.
Conclusions: Combining the study of this paper and evaporite deposits data of other salt lakes in the Qaidam Basin, this paper proposes that the penultimate glacial period MIS6 and the last glaciation MIS2 are two important salt- forming periods of the late Quaternary in the Qaidam Basin, and the cold and dry climate of the glacial period is favorable for salt deposits such as halite and mirabilite. The fundamental reason for salt deposit in the glacial environment in the Qaidam Basin is the expansion of glacier scale in the surrounding mountains, and the dry and cold glacial climate, resulting in the reduction of the recharge volume of the salt lakes in the Qaidam Basin. Besides, the temperature decrease during MIS6 and MIS2 is the direct genesis of the deposit of cold- phase salt minerals such as mirabilite and epsomite. |
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| Keywords: | Qaidam Basin salt lake evaporite deposit period penultimate glacial period last glaciation U- series dating |
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