{"title":"南澳大利亚 Wirrealpa 灰岩(寒武纪第 4 阶段)微生物堆积层中的微观结构和脉状硬岩","authors":"Hao Yun , Xingliang Zhang , Joachim Reitner","doi":"10.1016/j.palaeo.2024.112526","DOIUrl":null,"url":null,"abstract":"<div><div>Well-preserved, distinctive columnar microbialites were discovered in the Wirrealpa Limestone (Stage 4, Series 2 of Cambrian) of South Australia. However, further studies are still required to unveil the microstructure and formation process of these microbialites. A microbial buildup from the Wirrealpa Limestone examined herein suggests that the microbialitic columns are composed of densely-distributed, polymorphic, and patched fabrics produced by microbes. These fabrics are inter-framed by packstone sediments that characterized by calcareous metazoan skeletons and cerebroid ooids. The patched fabrics can be categorized into three types: 1) laminated ‘patches’, 2) homogeneous microsparitic ‘patches’ (mesoclots), and 3) cemented ‘patches’ containing tightly-packed chancelloriid sclerites. There are two preservational conditions of chancelloriid sclerites. After death of the chancelloriid individuals (belonging to <em>Chancelloria</em> and rare <em>Allonnia</em>) that dwelled among or near the microbial reef, abundant sclerites were exfoliated, transported, and concentrated. Then, some of them were cemented by microbial communities, forming the third type ‘patches’, while others were accumulated in the packstones within reefal cavities and inter-framework space along with many skeletal fragments from trilobites and mollusks. Thus, this lower Cambrian thrombolite-stromatolite complex was formed within an ecosystem lacking archaeocyaths but dominated by microbes (reef builders) and chancelloriids (reef dwellers).</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"655 ","pages":"Article 112526"},"PeriodicalIF":2.6000,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Microstructure and chancelloriid sclerites within a microbial buildup of the Wirrealpa Limestone (Cambrian Stage 4), South Australia\",\"authors\":\"Hao Yun , Xingliang Zhang , Joachim Reitner\",\"doi\":\"10.1016/j.palaeo.2024.112526\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><div>Well-preserved, distinctive columnar microbialites were discovered in the Wirrealpa Limestone (Stage 4, Series 2 of Cambrian) of South Australia. However, further studies are still required to unveil the microstructure and formation process of these microbialites. A microbial buildup from the Wirrealpa Limestone examined herein suggests that the microbialitic columns are composed of densely-distributed, polymorphic, and patched fabrics produced by microbes. These fabrics are inter-framed by packstone sediments that characterized by calcareous metazoan skeletons and cerebroid ooids. The patched fabrics can be categorized into three types: 1) laminated ‘patches’, 2) homogeneous microsparitic ‘patches’ (mesoclots), and 3) cemented ‘patches’ containing tightly-packed chancelloriid sclerites. There are two preservational conditions of chancelloriid sclerites. After death of the chancelloriid individuals (belonging to <em>Chancelloria</em> and rare <em>Allonnia</em>) that dwelled among or near the microbial reef, abundant sclerites were exfoliated, transported, and concentrated. Then, some of them were cemented by microbial communities, forming the third type ‘patches’, while others were accumulated in the packstones within reefal cavities and inter-framework space along with many skeletal fragments from trilobites and mollusks. Thus, this lower Cambrian thrombolite-stromatolite complex was formed within an ecosystem lacking archaeocyaths but dominated by microbes (reef builders) and chancelloriids (reef dwellers).</div></div>\",\"PeriodicalId\":19928,\"journal\":{\"name\":\"Palaeogeography, Palaeoclimatology, Palaeoecology\",\"volume\":\"655 \",\"pages\":\"Article 112526\"},\"PeriodicalIF\":2.6000,\"publicationDate\":\"2024-09-30\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Palaeogeography, Palaeoclimatology, Palaeoecology\",\"FirstCategoryId\":\"89\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0031018224005157\",\"RegionNum\":2,\"RegionCategory\":\"地球科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"GEOGRAPHY, PHYSICAL\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Palaeogeography, Palaeoclimatology, Palaeoecology","FirstCategoryId":"89","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0031018224005157","RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"GEOGRAPHY, PHYSICAL","Score":null,"Total":0}
Microstructure and chancelloriid sclerites within a microbial buildup of the Wirrealpa Limestone (Cambrian Stage 4), South Australia
Well-preserved, distinctive columnar microbialites were discovered in the Wirrealpa Limestone (Stage 4, Series 2 of Cambrian) of South Australia. However, further studies are still required to unveil the microstructure and formation process of these microbialites. A microbial buildup from the Wirrealpa Limestone examined herein suggests that the microbialitic columns are composed of densely-distributed, polymorphic, and patched fabrics produced by microbes. These fabrics are inter-framed by packstone sediments that characterized by calcareous metazoan skeletons and cerebroid ooids. The patched fabrics can be categorized into three types: 1) laminated ‘patches’, 2) homogeneous microsparitic ‘patches’ (mesoclots), and 3) cemented ‘patches’ containing tightly-packed chancelloriid sclerites. There are two preservational conditions of chancelloriid sclerites. After death of the chancelloriid individuals (belonging to Chancelloria and rare Allonnia) that dwelled among or near the microbial reef, abundant sclerites were exfoliated, transported, and concentrated. Then, some of them were cemented by microbial communities, forming the third type ‘patches’, while others were accumulated in the packstones within reefal cavities and inter-framework space along with many skeletal fragments from trilobites and mollusks. Thus, this lower Cambrian thrombolite-stromatolite complex was formed within an ecosystem lacking archaeocyaths but dominated by microbes (reef builders) and chancelloriids (reef dwellers).
期刊介绍:
Palaeogeography, Palaeoclimatology, Palaeoecology is an international medium for the publication of high quality and multidisciplinary, original studies and comprehensive reviews in the field of palaeo-environmental geology. The journal aims at bringing together data with global implications from research in the many different disciplines involved in palaeo-environmental investigations.
By cutting across the boundaries of established sciences, it provides an interdisciplinary forum where issues of general interest can be discussed.