S. Petri, P. C. Fonseca Giannini, A. Chahud, I. J. Sayeg
{"title":"圆锥形帐篷与硫酸盐蒸发岩的流动性有关:以巴西帕拉纳<e:1>盆地二叠纪的Irati组为例","authors":"S. Petri, P. C. Fonseca Giannini, A. Chahud, I. J. Sayeg","doi":"10.2110/jsr.2022.011","DOIUrl":null,"url":null,"abstract":"\n Tepee structures, associated with cracks and intraformational breccias, are found in the basal part of the Thin Rhythmites Bed of the Irati Formation. The rhythmite alternates dark gray mm-thick laminae, formed by dolomicrite with crenulated microlamination rich in organic clay, and intermediate gray laminae, formed by dolarenite with peloids. Some of the rhythmic pairs are separated from each other by thin horizons (< 0.5 mm) with a concentration of quartz pseudomorphs of gypsum and/or pores resulting from bioturbation or dissolution. The close association of the peloids with microrosettes of early authigenic sodium sulfate, a typical salt of nonmarine brines, is suggestive of its formation under cyanobacterial action, favored by hypersaline conditions in inland lakes. This is consistent with the closing of the connection between the Paraná Basin and the Panthalassic Ocean, as has been suggested for the final stages of Irati sedimentation. The tepees analyzed are related to diapiric features of massive light gray dolomicrite, which is distinguished under the microscope as being poorer in organic matter and for presenting coalesced peloids (clots) rich in sodium sulfate. The hydroplastic rheology, overpressure, and density gradient required for the upward injection of light gray dolomicrite are attributed to supersaturation in water and the presence of eodiagenetic low-density hydrated sulfates (e.g., mirabilite and thenardite). Thus, the processes that form the tepees studied here differ from those described in previous models of lacustrine and lagoon tepees, especially regarding the fundamental role of the expansion and mobility of the sulfated dolomite sediment, controlled by the lake's hydrology and by the elevation of groundwater, without necessarily involving subaerial exposure processes.","PeriodicalId":17044,"journal":{"name":"Journal of Sedimentary Research","volume":null,"pages":null},"PeriodicalIF":2.0000,"publicationDate":"2022-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Tepees associated with mobility of evaporite sulfate: The case of the Irati Formation, Permian of Paraná Basin, Brazil\",\"authors\":\"S. Petri, P. C. Fonseca Giannini, A. Chahud, I. J. Sayeg\",\"doi\":\"10.2110/jsr.2022.011\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"\\n Tepee structures, associated with cracks and intraformational breccias, are found in the basal part of the Thin Rhythmites Bed of the Irati Formation. The rhythmite alternates dark gray mm-thick laminae, formed by dolomicrite with crenulated microlamination rich in organic clay, and intermediate gray laminae, formed by dolarenite with peloids. Some of the rhythmic pairs are separated from each other by thin horizons (< 0.5 mm) with a concentration of quartz pseudomorphs of gypsum and/or pores resulting from bioturbation or dissolution. The close association of the peloids with microrosettes of early authigenic sodium sulfate, a typical salt of nonmarine brines, is suggestive of its formation under cyanobacterial action, favored by hypersaline conditions in inland lakes. This is consistent with the closing of the connection between the Paraná Basin and the Panthalassic Ocean, as has been suggested for the final stages of Irati sedimentation. The tepees analyzed are related to diapiric features of massive light gray dolomicrite, which is distinguished under the microscope as being poorer in organic matter and for presenting coalesced peloids (clots) rich in sodium sulfate. The hydroplastic rheology, overpressure, and density gradient required for the upward injection of light gray dolomicrite are attributed to supersaturation in water and the presence of eodiagenetic low-density hydrated sulfates (e.g., mirabilite and thenardite). Thus, the processes that form the tepees studied here differ from those described in previous models of lacustrine and lagoon tepees, especially regarding the fundamental role of the expansion and mobility of the sulfated dolomite sediment, controlled by the lake's hydrology and by the elevation of groundwater, without necessarily involving subaerial exposure processes.\",\"PeriodicalId\":17044,\"journal\":{\"name\":\"Journal of Sedimentary Research\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":2.0000,\"publicationDate\":\"2022-11-30\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of Sedimentary Research\",\"FirstCategoryId\":\"89\",\"ListUrlMain\":\"https://doi.org/10.2110/jsr.2022.011\",\"RegionNum\":4,\"RegionCategory\":\"地球科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"GEOLOGY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Sedimentary Research","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.2110/jsr.2022.011","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"GEOLOGY","Score":null,"Total":0}
Tepees associated with mobility of evaporite sulfate: The case of the Irati Formation, Permian of Paraná Basin, Brazil
Tepee structures, associated with cracks and intraformational breccias, are found in the basal part of the Thin Rhythmites Bed of the Irati Formation. The rhythmite alternates dark gray mm-thick laminae, formed by dolomicrite with crenulated microlamination rich in organic clay, and intermediate gray laminae, formed by dolarenite with peloids. Some of the rhythmic pairs are separated from each other by thin horizons (< 0.5 mm) with a concentration of quartz pseudomorphs of gypsum and/or pores resulting from bioturbation or dissolution. The close association of the peloids with microrosettes of early authigenic sodium sulfate, a typical salt of nonmarine brines, is suggestive of its formation under cyanobacterial action, favored by hypersaline conditions in inland lakes. This is consistent with the closing of the connection between the Paraná Basin and the Panthalassic Ocean, as has been suggested for the final stages of Irati sedimentation. The tepees analyzed are related to diapiric features of massive light gray dolomicrite, which is distinguished under the microscope as being poorer in organic matter and for presenting coalesced peloids (clots) rich in sodium sulfate. The hydroplastic rheology, overpressure, and density gradient required for the upward injection of light gray dolomicrite are attributed to supersaturation in water and the presence of eodiagenetic low-density hydrated sulfates (e.g., mirabilite and thenardite). Thus, the processes that form the tepees studied here differ from those described in previous models of lacustrine and lagoon tepees, especially regarding the fundamental role of the expansion and mobility of the sulfated dolomite sediment, controlled by the lake's hydrology and by the elevation of groundwater, without necessarily involving subaerial exposure processes.
期刊介绍:
The journal is broad and international in scope and welcomes contributions that further the fundamental understanding of sedimentary processes, the origin of sedimentary deposits, the workings of sedimentary systems, and the records of earth history contained within sedimentary rocks.