Hanan S. Badawy, Soheir H. El-Shazly, Dina M. Sayed, Ibrahim M. Abd El-Gaied, Yasser F. Salama
{"title":"埃及东部沙漠北部上新世岩石演替的地貌层次和微观特征:推断特提斯地台的频繁次生暴露和相关古气候","authors":"Hanan S. Badawy, Soheir H. El-Shazly, Dina M. Sayed, Ibrahim M. Abd El-Gaied, Yasser F. Salama","doi":"10.1007/s13146-024-01003-x","DOIUrl":null,"url":null,"abstract":"<p>The evolution of the upward stacking pattern of shoaling, which contains microscopic features of paleosols and calcretes in the Upper Eocene Beni-Suef and Maadi Formations along the Beni-Suef-Zaafarana road in the northern Eastern Desert, Egypt, is related to frequent intervals of subaerial exposure. The work was achieved through an integrated approach of outcrop observations and microfacies analysis using polarizing microscopy. The study reveals the presence of sixteen microfacies types grouped into six facies associations, representing a mixed clastics-carbonates ramp setting. The ramp facies belts consist of a back ramp restricted mudflat/supratidal flat and lagoon, protected and low-energy inner ramp, open inner ramp, carbonate shoal, and open middle/outer ramp. The cycles commonly start with open inner ramp carbonate facies and end with mudflat clastic facies/subaerial exposure surfaces. The vertical changes in the depositional environments indicate that the facies were deposited within a highly tectonic active area that was consequently influenced by the transgression and regression of the Tethys. Microscopic features of subaerial exposure, including <i>Microcodium</i> crystal aggregates, <i>crystallaria</i>, rhizoliths, <i>Stromatolite</i>-like structures, sheet cracks, fenestrae, microbial mat laminae and dissolution of bioclasts, commonly occur in the topmost part of the cycles. The documented microfabric features in the study area provide strong evidence of the regular emergence of the southern Tethys platform in Egypt during the Late Eocene. They point to an intermediate palaeoclimate, involving conditions ranging from semi-arid to sub-humid. Subaerial disconformities and associated diagenesis/pedogenesis features, as recorded in the studied units, are not widely reported in the upper Eocene carbonates in Egypt.</p>","PeriodicalId":9612,"journal":{"name":"Carbonates and Evaporites","volume":null,"pages":null},"PeriodicalIF":1.1000,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Facies hierarchy and microscopic features of upper Eocene rock succession, northern Eastern Desert, Egypt: inference on frequent subaerial exposure of Tethys platform and relevant palaeoclimates\",\"authors\":\"Hanan S. Badawy, Soheir H. El-Shazly, Dina M. Sayed, Ibrahim M. Abd El-Gaied, Yasser F. Salama\",\"doi\":\"10.1007/s13146-024-01003-x\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p>The evolution of the upward stacking pattern of shoaling, which contains microscopic features of paleosols and calcretes in the Upper Eocene Beni-Suef and Maadi Formations along the Beni-Suef-Zaafarana road in the northern Eastern Desert, Egypt, is related to frequent intervals of subaerial exposure. The work was achieved through an integrated approach of outcrop observations and microfacies analysis using polarizing microscopy. The study reveals the presence of sixteen microfacies types grouped into six facies associations, representing a mixed clastics-carbonates ramp setting. The ramp facies belts consist of a back ramp restricted mudflat/supratidal flat and lagoon, protected and low-energy inner ramp, open inner ramp, carbonate shoal, and open middle/outer ramp. The cycles commonly start with open inner ramp carbonate facies and end with mudflat clastic facies/subaerial exposure surfaces. The vertical changes in the depositional environments indicate that the facies were deposited within a highly tectonic active area that was consequently influenced by the transgression and regression of the Tethys. Microscopic features of subaerial exposure, including <i>Microcodium</i> crystal aggregates, <i>crystallaria</i>, rhizoliths, <i>Stromatolite</i>-like structures, sheet cracks, fenestrae, microbial mat laminae and dissolution of bioclasts, commonly occur in the topmost part of the cycles. The documented microfabric features in the study area provide strong evidence of the regular emergence of the southern Tethys platform in Egypt during the Late Eocene. They point to an intermediate palaeoclimate, involving conditions ranging from semi-arid to sub-humid. Subaerial disconformities and associated diagenesis/pedogenesis features, as recorded in the studied units, are not widely reported in the upper Eocene carbonates in Egypt.</p>\",\"PeriodicalId\":9612,\"journal\":{\"name\":\"Carbonates and Evaporites\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":1.1000,\"publicationDate\":\"2024-09-05\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Carbonates and Evaporites\",\"FirstCategoryId\":\"89\",\"ListUrlMain\":\"https://doi.org/10.1007/s13146-024-01003-x\",\"RegionNum\":4,\"RegionCategory\":\"地球科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q3\",\"JCRName\":\"GEOLOGY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Carbonates and Evaporites","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.1007/s13146-024-01003-x","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"GEOLOGY","Score":null,"Total":0}
Facies hierarchy and microscopic features of upper Eocene rock succession, northern Eastern Desert, Egypt: inference on frequent subaerial exposure of Tethys platform and relevant palaeoclimates
The evolution of the upward stacking pattern of shoaling, which contains microscopic features of paleosols and calcretes in the Upper Eocene Beni-Suef and Maadi Formations along the Beni-Suef-Zaafarana road in the northern Eastern Desert, Egypt, is related to frequent intervals of subaerial exposure. The work was achieved through an integrated approach of outcrop observations and microfacies analysis using polarizing microscopy. The study reveals the presence of sixteen microfacies types grouped into six facies associations, representing a mixed clastics-carbonates ramp setting. The ramp facies belts consist of a back ramp restricted mudflat/supratidal flat and lagoon, protected and low-energy inner ramp, open inner ramp, carbonate shoal, and open middle/outer ramp. The cycles commonly start with open inner ramp carbonate facies and end with mudflat clastic facies/subaerial exposure surfaces. The vertical changes in the depositional environments indicate that the facies were deposited within a highly tectonic active area that was consequently influenced by the transgression and regression of the Tethys. Microscopic features of subaerial exposure, including Microcodium crystal aggregates, crystallaria, rhizoliths, Stromatolite-like structures, sheet cracks, fenestrae, microbial mat laminae and dissolution of bioclasts, commonly occur in the topmost part of the cycles. The documented microfabric features in the study area provide strong evidence of the regular emergence of the southern Tethys platform in Egypt during the Late Eocene. They point to an intermediate palaeoclimate, involving conditions ranging from semi-arid to sub-humid. Subaerial disconformities and associated diagenesis/pedogenesis features, as recorded in the studied units, are not widely reported in the upper Eocene carbonates in Egypt.
期刊介绍:
Established in 1979, the international journal Carbonates and Evaporites provides a forum for the exchange of concepts, research and applications on all aspects of carbonate and evaporite geology. This includes the origin and stratigraphy of carbonate and evaporite rocks and issues unique to these rock types: weathering phenomena, notably karst; engineering and environmental issues; mining and minerals extraction; and caves and permeability.
The journal publishes current information in the form of original peer-reviewed articles, invited papers, and reports from meetings, editorials, and book and software reviews. The target audience includes professional geologists, hydrogeologists, engineers, geochemists, and other researchers, libraries, and educational centers.