风成砂岩的显微特征与鉴别方法——以山西宁武—静乐盆地天池河组为例  

Microscopic Features and Identification Method of Aeolian Sandstone:A case study from the Tianchihe Formation,Ningwu-Jingle Basin,Shanxi province

作　　者：丁家翔 许欢 杜研 苑婷媛 张毕辉 刘高政 何柯衡 DING JiaXiang;XU Huan;DU Yan;YUAN TingYuan;ZHANG BiHui;LIU GaoZheng;HE KeHeng(Yunnan Key Laboratory of Earth System Science,Kunming 650500,China;School of Earth Science,Yunnan University,Kunming 650500,China)

机构地区：[1]云南省地球系统科学重点实验室,昆明650500 [2]云南大学地球科学学院,昆明650500

出　　处：《沉积学报》2025年第2期539-554,共16页Acta Sedimentologica Sinica

基　　金：国家自然科学基金项目(41802009);云南省中青年学术与技术带头人后备人才项目(202205AC160020)。

摘　　要：【目的】在沉积学研究中,如何有效地区分风成与水成沉积长期以来都是地学界关注的焦点,同时也是难点所在。虽然部分宏观尺度沉积特征(如风成波痕、风成沙波层、条纹层等)能够为风成砂岩的鉴别提供有力支撑,但由于露头出露条件的差异,上述特征很难被完全识别出来。相比之下,风成砂岩特征性的微观结构(如高成分与结构成熟度、稳定单矿物表面结构等)却不受露头条件限制,这为鉴别风成沉积提供了有效途径。【方法】以山西宁武—静乐盆地晚侏罗世风成和水成砂岩为例,对二者开展了一系列微观层面分析。【结果与结论】风成砂岩相较于河流砂岩具有高成分/结构成熟度以及存在特征性风成地层,各风成地层之间具有不同的粒度特征,风成砂岩单矿物颗粒表面具有碟形坑、新月形坑、上翻解理薄片等指示风成成因的显微结构,同时风成石英颗粒表面具有高铁/锰含量等特征。综合薄片、粒度、扫描电镜和能谱的研究,提出单矿物颗粒表面的碟形撞击坑以及具有逆粒序的风成沙波层能够作为风成砂岩的特有鉴别指标。鉴于风成砂岩的显微特征常具有多解性,建议采用多指标联合分析风成沉积成因。[Objective]In sedimentological studies,effectively distinguishing the aeolian and hydrogenic deposits has long garnered series academic attention;however,it remains difficult.Although certain macro-scale sedimentary features(such as wind-ripple marks,wind-ripple strata,and pin stripe laminations)can provide favorable support for the identification of aeolian deposits,owing to the differences in outcrops exposure conditions,the features mentioned above are difficult to accurately recognize.In contrast,the characteristic microtextures of aeolian deposits,such as high composition,structural maturity,and stable mineral surface morphology,are not limited by outcrop conditions,which provides an effective method for identifying aeolian deposits.[Methods]In this study,taking Late Jurassic aeolian and hydrogenic deposits from the Ningwu-Jingle basin of Shanxi Province as an example,a series of micro-scale analyses were conducted on the two types of sandstones.[Results and Conclusions]The aeolian sandstone has high composition and structural maturity compared to fluvial sandstone,between different aeolian strate with varying grain size characteristics,microscopic structures such as dished pits,crescentic percussion marks and upturned plates on the surface of mineral particles indicate the aeolian origin of the sandstone,additionally,aeolian quartz particles exhibit high levels of ferrum and manganese.Based on the combined of thin section analysis,grain size analysis,scanning electron microscopy,and energy spectrum analysis,we propose that the dished pits on the surface of mineral particles and wind-ripple strata with inverse grain size grading can be used as the unique identification indicators of aeolian deposits.Owing to the explanatory ambiguity of the microscopic characteristics of most aeolian deposits,we recommend adopting a multi-index combined method to analyze the genesis of aeolian deposits.

关 键 词：风成砂岩 薄片 粒度 扫描电镜 能谱 

分 类 号：P512.2[天文地球—地质学]