埋藏哈密翼龙化石的雅丹风化的光谱分析——以大海道2号水源地雅丹为例  

Spectral Analysis of the Weathering of Yardang Buried Pterosaur Fossils——A Case Study of Yardang Near the No.2 Water Source of Dahaidao

作　　者：赵文华 韩向娜 陈熜 汪筱林[2,3,4] ZHAO Wen-hua;HAN Xiang-na;CHEN Cong;WANG Xiao-lin(Institute for Cultural Heritage and History of Science&Technology,University of Science and Technology Beijing,Beijing 100083,China;Key Laboratory of Vertebrate Evolution and Human Origins,Institute of Vertebrate Paleontology and Paleoanthropology,Chinese Academy of Sciences,Beijing 100044,China;Center for Excellence in Life and Paleoenvironment,CAS,Beijing 100044,China;College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]北京科技大学科技史与文化遗产研究院,北京100083 [2]中国科学院古脊椎动物与古人类研究所脊椎动物演化与人类起源重点实验室,北京100044 [3]中国科学院生物演化与环境卓越创新中心,北京100044 [4]中国科学院大学地球与行星科学学院,北京100049

出　　处：《光谱学与光谱分析》2022年第2期561-567,共7页Spectroscopy and Spectral Analysis

基　　金：国家自然科学基金项目(41572020,41688103);中央高校基本科研业务费(FRF-BR-19-019A,FRF-MP-20-53)资助。

摘　　要：新疆哈密地区翼龙化石具有极高的科学研究价值。哈密翼龙动物群主要埋藏在早白垩世湖相地层形成的雅丹中,富集在风暴沉积层。化石一旦暴露地表,就会发生不同程度的自然风化破碎,尤其是见水或受潮后风化更为严重。哈密大海道2号水源地附近的雅丹底部由于地下水和间歇性地表水的作用,发生了严重的盐碱析出导致的强烈风化现象,造成雅丹下部剥落侵蚀和上层雅丹重力坍塌,从下到上不同地层的风化程度差异较大,底部地层的风化最为剧烈。对大海道雅丹地层剖面取样,利用多种分析方法确定每一层的岩性和可溶盐种类,从微观上揭示雅丹风化的机理。偏光显微观察和X射线衍射(XRD)结果显示每一层都含有石英、长石、方解石和粘土矿物,矿物组成无较大差异,但粘土含量差别较大。精确的可溶盐种类鉴别方法,包括离子色谱(IC)确定出样品中可溶盐离子含量及种类,拉曼光谱(Raman)和傅里叶变换红外光谱(FTIR)鉴别出样品中的硝酸盐和硫酸盐,扫描电子显微镜能谱仪(SEM-EDS)鉴别出氯盐、硝酸盐和硫酸盐。结果显示雅丹各风化层中最底层可溶盐主要是NaCl和Na_(2)SO_(4),第二层是NaCl和CaCl_(2),第三层是NaCl,盐种类/含量的差别是此处雅丹从下到上发生不同风化现象的重要原因。结合大海道雅丹所处的气候地理环境(极干旱高盐碱地区、水源地附近),探讨水盐活动规律并关联风化表现,分析该处雅丹风化原因,内因是每层沉积岩的岩性不同,外因是水和盐(NaCl,Na_(2)SO_(4),CaCl_(2))的共同作用下,强烈的水盐活动造成了埋藏有哈密翼龙化石的雅丹严重化学风化。这一风化机理也可很好地解释哈密翼龙化石及其围岩层受潮后的强烈风化破碎现象。The pterosaur fossils in the Hami area of Xinjiang are very important.The Hami Pterosaur Fauna is mainly buried in the Yardang of the Early Cretaceous lacustrine strata and enriched in tempestite.Once exposed up the ground,the fossils will undergo different degrees of natural weathering,especially when exposed to water or moisture.Due to the action of groundwater and intermittent runoff,serious salt efflorescence was found at the bottom of Yardang near the No.2 water source of Dahaidao,which caused the spalling of rock and the collapse of the upper Yardang.The weathering phenomenon of different layers from bottom to top are quite different,and the most intense weathering is found in the bottom rock.By sampling along Yardang stratigraphic section,the lithology and soluble salt types of each layer are determined by using scientific analysis technology,from a microscopic perspective to explain the mechanism of weathering of this Yardang.Polarized light microscopic observation and X-ray diffraction(XRD)results show that each stratum contains quartz,feldspar,calcite,and clay minerals.It is no difference in mineral composition,but there is a great difference in clay content.Accurate methods for identifying soluble salts types include ion chromatography(IC)to determine the content and types of soluble salt ions,Raman spectroscopy(Raman)and Fourier transform infrared spectroscopy(FTIR)to identify nitrate and sulfate,and the Scanning Electron Microscopy Energy Spectrometer(SEM-EDS)to distinguish chloride,nitrate,and sulfate.The results show that the soluble salts in the lowest stratum are mainly NaCl and Na_(2)SO_(4),the middle stratum is NaCl and CaCl_(2),and the upper stratum is NaCl.The difference in salt type/content in rock layers is important for diverse weathering setting.Combined with the climate and geographical environment of this Yardang(extremely arid area,near the water source),this paper discusses the law of water and salt activities linked to the weathering setting,and illustrates the main weathering mechan

关 键 词：哈密翼龙 雅丹 风化机理 可溶盐 哈密 

分 类 号：Q915.2[天文地球—古生物学与地层学]