中更新世以来的哈尔滨黄土物源变化——来自TIMA自动定量矿物的证据  

Changing provenance of Harbin loess since the Middle Pleistocene:evidence from TIMA automated quantification of minerals

作　　者：汪进秋 谢远云[1,2] 康春国 迟云平[1,2] 孙磊 吴鹏 魏振宇 Wang Jinqiu;Xie Yuanyun;Kang Chunguo;Chi Yunping;Sun Lei;Wu Peng;Wei Zhenyu(College of Geographic Science,Harbin Normal University,Harbin 150025,China;Heilongjiang Province Key Laboratory of Geographical Environment Monitoring and Spatial Information Service in Cold Regions,Harbin Normal University,Harbin 150025,China;School of Geography and Tourism,Harbin University,Harbin 150086,China)

机构地区：[1]哈尔滨师范大学地理科学学院,黑龙江哈尔滨150025 [2]哈尔滨师范大学寒区地理环境监测与空间信息服务黑龙江省重点实验室,黑龙江哈尔滨150025 [3]哈尔滨学院地理与旅游学院,黑龙江哈尔滨150086

出　　处：《中国沙漠》2022年第5期25-35,共11页Journal of Desert Research

基　　金：黑龙江省自然科学基金项目(LH2020D009);国家自然科学基金项目(42171006,41871013)。

摘　　要：黄土隐含丰富的古气候信息,了解其物源变化对理解亚洲内陆干旱化、大气环流模式和亚洲季风演变至关重要。哈尔滨荒山剖面地层出露厚度大,地层连续,保存了松嫩平原最完整的黄土-古土壤序列。此外,重矿物在河流源-汇研究中得到广泛应用,但在风成沉积物中较少。定量矿物学方法分析速度快,能在较短时间内获得大量数据。因此,我们对哈尔滨黄土-古土壤序列进行TIMA(TESCAN Integrated Mineral Analyzer)自动定量矿物分析及年代学(OSL、ESR和14C)测试,以期了解哈尔滨黄土在冰期-间冰期时间尺度上的物源变化。结果表明:TIMA方法鉴别的矿物种类高于传统方法,且TIMA定量的重矿物含量与传统方法相比存在一定的差异,但两者揭示的重矿物组合基本一致。黄土-古土壤序列在15.1 m(234.2 ka)上、下地层的20—63μm组分的铁板钛矿、闪石类、锆石、磷灰石、金红石、钛铁矿、铬铁矿、榍石、辉石以及重矿物特征指数(ZTR和GZi)等存在明显不同的变化特征;然而,除了铁板钛矿和独居石外,<20μm组分并没有表现出如此特征。黄土-古土壤序列上、下地层重矿物组成的差异指示了哈尔滨黄土物源的变化。15.1 m以下,哈尔滨黄土除了接受松嫩沙地的近源粉尘贡献外,也有远源(比如,浑善达克和科尔沁沙地)粉尘的贡献。随着干旱化气候的加剧,松嫩沙地范围扩大,使得15.1 m以上黄土的远源贡献比例减少,近源贡献显著增加。即增强的气候干旱化导致的松嫩沙地粉尘源区范围扩大,是哈尔滨黄土物源发生变化的主要原因。Loess contains abundant paleoclimatic information,and an understanding of its provenance variability is essential for understanding the climate aridification of inland Asia,atmospheric circulation patterns,and the evolution of the Asian monsoon. The large outcrop thickness and stratigraphic continuousness of Harbin Huangshan section,preserve the most complete loess-paleosol sequence in the Songnen Plain. Heavy minerals are widely used in river source-to-sink studies,but are relatively rare in aeolian sediments. Quantitative mineralogical methods are fast in analysis and can obtain a large amount of data in a relatively short time. Therefore,the TIMA(TESCAN Integrated Mineral Analyzer)automated quantitative mineral analysis and chronological tests(OSL,ESR and14C)were performed on the Harbin loess-paleosol sequences with a view to understanding provenance change on glacial-interglacial time scale. The results showed that the mineral species identified by the TIMA method were higher than conventional method. Despite some differences in the identification results of the two methods,the revealed heavy mineral assemblages are basically the same. The loess-paleosol sequence is characterized by distinctly different variations of pseudobrookite,amphibole,zircon,apatite,rutile,ilmenite,chromite,titanite,pyroxene and heavy mineral characterization indices(e.g.,ZTR and GZi)in the 20-63 μm fraction of the upper and lower strata at 15.1 m(~234.2 ka). However,the <20 μm fraction does not exhibit such characteristics,with the exception of pseudobrookite and monazite. Differences in the heavy mineral composition of the upper and lower horizons of the loess-paleosol sequence are indicative of changes in the provenance of the Harbin loess. Below 15.1 m,Harbin loess not only receives the contribution of near-source dust from Songnen Sandy Land,but also has the contribution of dust from distant sources(i.e.,Onqin Daga Sandy Land and Horqin Sandy Land). With the intensification of aridification climate,the expansion of the extent of

关 键 词：哈尔滨 黄土 重矿物 TIMA分析 物源变化 干旱化 

分 类 号：P531[天文地球—古生物学与地层学]