南非水牛河内层的庞戈拉超群白云石:面貌、成分及对中生代碳酸盐沉积的影响

IF 3.2 2区 地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY
M. Siahi , A. Hofmann , J. Dixon , A. Wilson , C. Mayr , L. Kapesi
{"title":"南非水牛河内层的庞戈拉超群白云石:面貌、成分及对中生代碳酸盐沉积的影响","authors":"M. Siahi ,&nbsp;A. Hofmann ,&nbsp;J. Dixon ,&nbsp;A. Wilson ,&nbsp;C. Mayr ,&nbsp;L. Kapesi","doi":"10.1016/j.precamres.2024.107493","DOIUrl":null,"url":null,"abstract":"<div><p>The Mesoarchaean Pongola Supergroup of South Africa hosts the oldest succession of stromatolitic carbonates deposited in an intracontinental setting. In this study, carbonates within two (tectono-) stratigraphic units in the Buffalo River inlier were investigated. Stratiform stromatolite and wave-ripple-laminated dolostone facies are the most common and are interpreted to have formed in a tide-dominated shallow-marine environment. Dolostones typically contain a large amount of siliciclastic detritus, and small domal stromatolites are commonly found scattered in subtidal sandstone facies. The carbonates experienced deformation and greenschist facies metamorphic conditions at peak temperatures of ∼ 450 ± 50 °C. Analyses for major, trace and rare earth elements (REEs) along with carbon, oxygen and strontium isotopes have been undertaken on the best-preserved samples. Their REE + Y distribution patterns reflect their marine origin, with positive La<sub>SN</sub>, Gd<sub>SN</sub> and Y<sub>SN</sub> anomalies, super-chondritic Y/Ho ratios, and depleted light REEs relative to heavy REEs. The δ<sup>13</sup>C<sub>VPDB</sub> and δ<sup>18</sup>O<sub>VPDB</sub> values least affected by diagenetic and metamorphic overprints are 2.2 ‰ and −16.1 ‰, respectively. The least radiogenic <sup>87</sup>Sr/<sup>86</sup>Sr ratio is 0.704 and reflects isotopic exchange with a siliciclastic component. Despite their alteration, the carbonates of the Buffalo River inlier provide additional constraints on microbial carbonate deposition on the Earth oldest preserved craton. They can be traced laterally for several tens of kilometres and point to environmental conditions suitable for the deposition and preservation of marine carbonate rocks 3.0 Ga ago.</p></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"411 ","pages":"Article 107493"},"PeriodicalIF":3.2000,"publicationDate":"2024-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0301926824002067/pdfft?md5=69e1759e425b6dfd2302b7028c5bee4a&pid=1-s2.0-S0301926824002067-main.pdf","citationCount":"0","resultStr":"{\"title\":\"Pongola Supergroup dolostones from the Buffalo River inlier, South Africa: facies, composition and implications for Mesoarchaean carbonate deposition\",\"authors\":\"M. Siahi ,&nbsp;A. Hofmann ,&nbsp;J. Dixon ,&nbsp;A. Wilson ,&nbsp;C. Mayr ,&nbsp;L. Kapesi\",\"doi\":\"10.1016/j.precamres.2024.107493\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>The Mesoarchaean Pongola Supergroup of South Africa hosts the oldest succession of stromatolitic carbonates deposited in an intracontinental setting. In this study, carbonates within two (tectono-) stratigraphic units in the Buffalo River inlier were investigated. Stratiform stromatolite and wave-ripple-laminated dolostone facies are the most common and are interpreted to have formed in a tide-dominated shallow-marine environment. Dolostones typically contain a large amount of siliciclastic detritus, and small domal stromatolites are commonly found scattered in subtidal sandstone facies. The carbonates experienced deformation and greenschist facies metamorphic conditions at peak temperatures of ∼ 450 ± 50 °C. Analyses for major, trace and rare earth elements (REEs) along with carbon, oxygen and strontium isotopes have been undertaken on the best-preserved samples. Their REE + Y distribution patterns reflect their marine origin, with positive La<sub>SN</sub>, Gd<sub>SN</sub> and Y<sub>SN</sub> anomalies, super-chondritic Y/Ho ratios, and depleted light REEs relative to heavy REEs. The δ<sup>13</sup>C<sub>VPDB</sub> and δ<sup>18</sup>O<sub>VPDB</sub> values least affected by diagenetic and metamorphic overprints are 2.2 ‰ and −16.1 ‰, respectively. The least radiogenic <sup>87</sup>Sr/<sup>86</sup>Sr ratio is 0.704 and reflects isotopic exchange with a siliciclastic component. Despite their alteration, the carbonates of the Buffalo River inlier provide additional constraints on microbial carbonate deposition on the Earth oldest preserved craton. They can be traced laterally for several tens of kilometres and point to environmental conditions suitable for the deposition and preservation of marine carbonate rocks 3.0 Ga ago.</p></div>\",\"PeriodicalId\":49674,\"journal\":{\"name\":\"Precambrian Research\",\"volume\":\"411 \",\"pages\":\"Article 107493\"},\"PeriodicalIF\":3.2000,\"publicationDate\":\"2024-07-14\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://www.sciencedirect.com/science/article/pii/S0301926824002067/pdfft?md5=69e1759e425b6dfd2302b7028c5bee4a&pid=1-s2.0-S0301926824002067-main.pdf\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Precambrian Research\",\"FirstCategoryId\":\"89\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0301926824002067\",\"RegionNum\":2,\"RegionCategory\":\"地球科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"GEOSCIENCES, MULTIDISCIPLINARY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Precambrian Research","FirstCategoryId":"89","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0301926824002067","RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"GEOSCIENCES, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0

摘要

南非中始新世庞戈拉超群(Pongola Supergroup)拥有大陆内环境中沉积的最古老的叠层碳酸盐岩演替。在这项研究中,对水牛河(Buffalo River)内层的两个(构造)地层单元中的碳酸盐进行了调查。层状叠层石和波浪纹层状白云石面是最常见的,被认为是在潮汐为主的浅海环境中形成的。白云石中通常含有大量硅质碎屑,潮下砂岩面中通常散布着小型穹隆叠层石。碳酸盐岩经历了变形和绿泥石面变质条件,峰值温度为 ∼ 450 ± 50 °C。对保存最完好的样本进行了主要、微量和稀土元素(REEs)以及碳、氧和锶同位素分析。它们的 REE + Y 分布模式反映了其海洋起源,LaSN、GdSN 和 YSN 呈正异常,Y/Ho 比值超软玉体,相对于重 REE,轻 REE 含量低。受成岩和变质叠加影响最小的δ13CVPDB和δ18OVPDB值分别为2.2‰和-16.1‰。放射性最小的 87Sr/86Sr 比率为 0.704,反映了与硅质成分的同位素交换。尽管水牛河内页岩的碳酸盐发生了蚀变,但它们为地球上保存最古老的陨石坑的微生物碳酸盐沉积提供了额外的约束条件。它们可以横向追踪几十公里,并指向适合 3.0 Ga 前海洋碳酸盐岩沉积和保存的环境条件。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Pongola Supergroup dolostones from the Buffalo River inlier, South Africa: facies, composition and implications for Mesoarchaean carbonate deposition

The Mesoarchaean Pongola Supergroup of South Africa hosts the oldest succession of stromatolitic carbonates deposited in an intracontinental setting. In this study, carbonates within two (tectono-) stratigraphic units in the Buffalo River inlier were investigated. Stratiform stromatolite and wave-ripple-laminated dolostone facies are the most common and are interpreted to have formed in a tide-dominated shallow-marine environment. Dolostones typically contain a large amount of siliciclastic detritus, and small domal stromatolites are commonly found scattered in subtidal sandstone facies. The carbonates experienced deformation and greenschist facies metamorphic conditions at peak temperatures of ∼ 450 ± 50 °C. Analyses for major, trace and rare earth elements (REEs) along with carbon, oxygen and strontium isotopes have been undertaken on the best-preserved samples. Their REE + Y distribution patterns reflect their marine origin, with positive LaSN, GdSN and YSN anomalies, super-chondritic Y/Ho ratios, and depleted light REEs relative to heavy REEs. The δ13CVPDB and δ18OVPDB values least affected by diagenetic and metamorphic overprints are 2.2 ‰ and −16.1 ‰, respectively. The least radiogenic 87Sr/86Sr ratio is 0.704 and reflects isotopic exchange with a siliciclastic component. Despite their alteration, the carbonates of the Buffalo River inlier provide additional constraints on microbial carbonate deposition on the Earth oldest preserved craton. They can be traced laterally for several tens of kilometres and point to environmental conditions suitable for the deposition and preservation of marine carbonate rocks 3.0 Ga ago.

求助全文
通过发布文献求助,成功后即可免费获取论文全文。 去求助
来源期刊
Precambrian Research
Precambrian Research 地学-地球科学综合
CiteScore
7.20
自引率
28.90%
发文量
325
审稿时长
12 months
期刊介绍: Precambrian Research publishes studies on all aspects of the early stages of the composition, structure and evolution of the Earth and its planetary neighbours. With a focus on process-oriented and comparative studies, it covers, but is not restricted to, subjects such as: (1) Chemical, biological, biochemical and cosmochemical evolution; the origin of life; the evolution of the oceans and atmosphere; the early fossil record; palaeobiology; (2) Geochronology and isotope and elemental geochemistry; (3) Precambrian mineral deposits; (4) Geophysical aspects of the early Earth and Precambrian terrains; (5) Nature, formation and evolution of the Precambrian lithosphere and mantle including magmatic, depositional, metamorphic and tectonic processes. In addition, the editors particularly welcome integrated process-oriented studies that involve a combination of the above fields and comparative studies that demonstrate the effect of Precambrian evolution on Phanerozoic earth system processes. Regional and localised studies of Precambrian phenomena are considered appropriate only when the detail and quality allow illustration of a wider process, or when significant gaps in basic knowledge of a particular area can be filled.
×
引用
GB/T 7714-2015
复制
MLA
复制
APA
复制
导出至
BibTeX EndNote RefMan NoteFirst NoteExpress
×
提示
您的信息不完整,为了账户安全,请先补充。
现在去补充
×
提示
您因"违规操作"
具体请查看互助需知
我知道了
×
提示
确定
请完成安全验证×
copy
已复制链接
快去分享给好友吧!
我知道了
右上角分享
点击右上角分享
0
联系我们:info@booksci.cn Book学术提供免费学术资源搜索服务,方便国内外学者检索中英文文献。致力于提供最便捷和优质的服务体验。 Copyright © 2023 布克学术 All rights reserved.
京ICP备2023020795号-1
ghs 京公网安备 11010802042870号
Book学术文献互助
Book学术文献互助群
群 号:481959085
Book学术官方微信