{"title":"Gypsum lakes, sandflats and soils revealed from the Triassic Red Peak Formation of the Chugwater Group, north-central Wyoming","authors":"Maya Yamei Bradford, Kathleen C. Benison","doi":"10.1002/dep2.273","DOIUrl":null,"url":null,"abstract":"<p>Bedded gypsum is relatively common in bedded evaporites associated with red bed siliciclastics of Permo-Triassic Pangea. However, little attention has been paid to the textures of ancient gypsum, which can be used to refine interpretations of depositional environment and diagenetic history. This project describes the textures of bedded gypsum from an outcrop of the Triassic Red Peak Formation (Chugwater Group) near Greybull, Wyoming. Fieldwork, petrography and X-ray diffraction reveal three distinct lithologies of bedded gypsum: bottom-growth gypsum, laminated gypsum and clastic gypsum. Bottom-growth gypsum precipitated at the bottom of shallow saline surface water bodies. Laminated gypsum probably formed in shallow saline lakes and mudflats. Clastic gypsum units are composed of aeolian-reworked bottom-growth gypsum crystals deposited in sandflats. Red siliciclastic mudstones are characterised by their massive nature and abundant blocky peds. Detailed study of this outcrop of the Red Peak Formation shows that it formed in shallow saline lakes and associated mudflats, sandflats and desert soils.</p>","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":null,"pages":null},"PeriodicalIF":1.9000,"publicationDate":"2024-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dep2.273","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Depositional Record","FirstCategoryId":"89","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1002/dep2.273","RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"GEOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Bedded gypsum is relatively common in bedded evaporites associated with red bed siliciclastics of Permo-Triassic Pangea. However, little attention has been paid to the textures of ancient gypsum, which can be used to refine interpretations of depositional environment and diagenetic history. This project describes the textures of bedded gypsum from an outcrop of the Triassic Red Peak Formation (Chugwater Group) near Greybull, Wyoming. Fieldwork, petrography and X-ray diffraction reveal three distinct lithologies of bedded gypsum: bottom-growth gypsum, laminated gypsum and clastic gypsum. Bottom-growth gypsum precipitated at the bottom of shallow saline surface water bodies. Laminated gypsum probably formed in shallow saline lakes and mudflats. Clastic gypsum units are composed of aeolian-reworked bottom-growth gypsum crystals deposited in sandflats. Red siliciclastic mudstones are characterised by their massive nature and abundant blocky peds. Detailed study of this outcrop of the Red Peak Formation shows that it formed in shallow saline lakes and associated mudflats, sandflats and desert soils.
在与二叠三叠纪泛大陆红层硅质岩有关的层状蒸发岩中,层状石膏比较常见。然而,人们很少关注古石膏的纹理,而这些纹理可用于完善对沉积环境和成岩历史的解释。该项目描述了怀俄明州格雷布尔附近三叠纪红峰地层(楚格沃特组)露头的层状石膏的纹理。实地考察、岩相学和 X 射线衍射揭示了层状石膏的三种不同岩性:底部生长石膏、层状石膏和碎屑石膏。底生石膏沉淀在浅盐地表水体的底部。层状石膏可能形成于浅盐湖和泥滩。碎屑石膏单元由沉积于沙滩的底部生长石膏晶体经风化再加工而成。红色硅质泥岩的特点是块状和大量块状碎屑。对这一赤峰地层露头的详细研究表明,该地层形成于浅盐湖及相关的泥滩、沙滩和沙漠土壤中。