尼日利亚西南部古新世埃韦科罗地层的稀土元素地球化学:对土著输入、成岩蚀变、古氧化还原和沉积条件的影响

IF 1.1 4区 地球科学 Q3 GEOLOGY
Taiwo Ayodele Bolaji, Ajibola Rasidat Oyebamiji, Otobong Sunday Okon, Vincent Azubuike Ndukwe, Odinaka Stanley Ohaeri, Racheal Anuoluwapo Akinpelu
{"title":"尼日利亚西南部古新世埃韦科罗地层的稀土元素地球化学:对土著输入、成岩蚀变、古氧化还原和沉积条件的影响","authors":"Taiwo Ayodele Bolaji, Ajibola Rasidat Oyebamiji, Otobong Sunday Okon, Vincent Azubuike Ndukwe, Odinaka Stanley Ohaeri, Racheal Anuoluwapo Akinpelu","doi":"10.1007/s13146-024-00966-1","DOIUrl":null,"url":null,"abstract":"<p>The freshly exposed carbonate rock succession of the Ewekoro Formation (Palaeocene) was investigated to interpret its palaeoredox conditions and depositional environments based on microfacies, mineralogy and geochemical variations. Wackestone, packstone and mudstone are three carbonate microfacies identified from petrographic observations. Calcite is the dominant mineral phase, while quartz, dolomite and lizardite are minor phases. The dominance of CaCO<sub>3</sub> and the low SiO<sub>2</sub> and Al<sub>2</sub>O<sub>3</sub> in the limestones indicate a low detrital contribution during precipitation. The low U and U/Th ratios are associated with an environment characterised by oxygen-enrichment, while redox proxies of Ni/Co, V/Cr and V/(V + Ni) show substantial oxygenation (oxic to anoxic) in their respective sedimentary environments. The mean rare-earth elements contents in the examined samples (45.03 ppm) are greater than the characteristic values (28 ppm) in marine carbonates. The rare earth and Yttrium signature of these limestones shows a seawater-like pattern. However, the somewhat lower average Y/Ho ratio (35.70) than conventional seawater (44–74) implies that freshwater input in a coastal setting modifies the seawater to some extent. Except for a few elements, these samples are comparable to those of shallow-marine carbonates, formed in a seawater-influenced environment. The REEs data obtained from these limestones has provided baseline information on geochemistry with a potential to better understand the regional paleogeographic conditions of the Ewekoro Formation.</p>","PeriodicalId":9612,"journal":{"name":"Carbonates and Evaporites","volume":"47 1","pages":""},"PeriodicalIF":1.1000,"publicationDate":"2024-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Rare-earth elements geochemistry of the Palaeocene Ewekoro Formation, southwestern Nigeria: implications for terrigenous inputs, diagenetic alteration, palaeoredox and depositional conditions\",\"authors\":\"Taiwo Ayodele Bolaji, Ajibola Rasidat Oyebamiji, Otobong Sunday Okon, Vincent Azubuike Ndukwe, Odinaka Stanley Ohaeri, Racheal Anuoluwapo Akinpelu\",\"doi\":\"10.1007/s13146-024-00966-1\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p>The freshly exposed carbonate rock succession of the Ewekoro Formation (Palaeocene) was investigated to interpret its palaeoredox conditions and depositional environments based on microfacies, mineralogy and geochemical variations. Wackestone, packstone and mudstone are three carbonate microfacies identified from petrographic observations. Calcite is the dominant mineral phase, while quartz, dolomite and lizardite are minor phases. The dominance of CaCO<sub>3</sub> and the low SiO<sub>2</sub> and Al<sub>2</sub>O<sub>3</sub> in the limestones indicate a low detrital contribution during precipitation. The low U and U/Th ratios are associated with an environment characterised by oxygen-enrichment, while redox proxies of Ni/Co, V/Cr and V/(V + Ni) show substantial oxygenation (oxic to anoxic) in their respective sedimentary environments. The mean rare-earth elements contents in the examined samples (45.03 ppm) are greater than the characteristic values (28 ppm) in marine carbonates. The rare earth and Yttrium signature of these limestones shows a seawater-like pattern. However, the somewhat lower average Y/Ho ratio (35.70) than conventional seawater (44–74) implies that freshwater input in a coastal setting modifies the seawater to some extent. Except for a few elements, these samples are comparable to those of shallow-marine carbonates, formed in a seawater-influenced environment. The REEs data obtained from these limestones has provided baseline information on geochemistry with a potential to better understand the regional paleogeographic conditions of the Ewekoro Formation.</p>\",\"PeriodicalId\":9612,\"journal\":{\"name\":\"Carbonates and Evaporites\",\"volume\":\"47 1\",\"pages\":\"\"},\"PeriodicalIF\":1.1000,\"publicationDate\":\"2024-05-03\",\"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/s13146-024-00966-1\",\"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/s13146-024-00966-1","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"GEOLOGY","Score":null,"Total":0}
引用次数: 0

摘要

对新近出露的 Ewekoro 组(古新世)碳酸盐岩演替进行了研究,以根据微地层、矿物学和地球化学变化解释其古氧化还原条件和沉积环境。根据岩相观察,确定了瓦基岩、包裹岩和泥岩这三种碳酸盐微观岩相。方解石是主要矿物相,石英、白云石和蜥蜴石是次要矿物相。石灰岩中 CaCO3 占主导地位,SiO2 和 Al2O3 含量较低,这表明沉淀过程中的碎屑含量较低。低 U 和 U/Th 比值与富氧环境有关,而 Ni/Co、V/Cr 和 V/(V + Ni)的氧化还原代用指标则显示了各自沉积环境中的大量富氧(缺氧至缺氧)。样本中稀土元素的平均含量(百万分之 45.03)高于海洋碳酸盐的特征值(百万分之 28)。这些石灰岩的稀土和钇特征显示出类似海水的模式。然而,平均 Y/Ho 比率(35.70)略低于常规海水(44-74),这意味着沿海环境中的淡水输入在一定程度上改变了海水。除少数元素外,这些样本与在受海水影响的环境中形成的浅海碳酸盐样本相当。从这些灰岩中获得的 REEs 数据提供了地球化学的基线信息,有可能更好地了解 Ewekoro Formation 的区域古地理条件。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Rare-earth elements geochemistry of the Palaeocene Ewekoro Formation, southwestern Nigeria: implications for terrigenous inputs, diagenetic alteration, palaeoredox and depositional conditions

The freshly exposed carbonate rock succession of the Ewekoro Formation (Palaeocene) was investigated to interpret its palaeoredox conditions and depositional environments based on microfacies, mineralogy and geochemical variations. Wackestone, packstone and mudstone are three carbonate microfacies identified from petrographic observations. Calcite is the dominant mineral phase, while quartz, dolomite and lizardite are minor phases. The dominance of CaCO3 and the low SiO2 and Al2O3 in the limestones indicate a low detrital contribution during precipitation. The low U and U/Th ratios are associated with an environment characterised by oxygen-enrichment, while redox proxies of Ni/Co, V/Cr and V/(V + Ni) show substantial oxygenation (oxic to anoxic) in their respective sedimentary environments. The mean rare-earth elements contents in the examined samples (45.03 ppm) are greater than the characteristic values (28 ppm) in marine carbonates. The rare earth and Yttrium signature of these limestones shows a seawater-like pattern. However, the somewhat lower average Y/Ho ratio (35.70) than conventional seawater (44–74) implies that freshwater input in a coastal setting modifies the seawater to some extent. Except for a few elements, these samples are comparable to those of shallow-marine carbonates, formed in a seawater-influenced environment. The REEs data obtained from these limestones has provided baseline information on geochemistry with a potential to better understand the regional paleogeographic conditions of the Ewekoro Formation.

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
Carbonates and Evaporites
Carbonates and Evaporites 地学-地质学
CiteScore
2.80
自引率
14.30%
发文量
70
审稿时长
3 months
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.
×
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