Depositional condition of Paleoproterozoic Francevillian carbonate rocks revisited from rare earth element contents

作     者：Satoshi Yoshida Karen Bakakas Mayika Yuki Ishihara Mathieu Moussavou Hisashi Asanuma Tomohiko Sato Takafumi Hirata Cédric Ligna Yusuke Sawaki Amboise Edou-Minko Satoshi Yoshida;Karen Bakakas Mayika;Yuki Ishihara;Mathieu Moussavou;Hisashi Asanuma;Tomohiko Sato;Takafumi Hirata;Cédric Ligna;Yusuke Sawaki;Amboise Edou-Minko

作者机构：Department of Earth Science and AstronomyThe University of Tokyo3-8-1 Komaba Meguro-kuTokyo 153-8902Japan Center for Northeast Asian StudiesTohoku University41 KawauchiAoba-kuSendai 980-8576Japan Department of GeologyUniversitédes Sciences et Techniques de MasukuBP:90190025 FrancevilleGabon Department of Earth and Planetary ScienceThe University of Tokyo7-3-1 HongoBunkyo-kuTokyo 113-0033Japan Geochemical Research CenterThe University of Tokyo7-3-1HongoBunkyo-kuTokyo 113-0033Japan Graduate School of Human and Environmental StudiesKyoto UniversityYoshida-nihonmatsuSakyo-kuKyoto 606-8501Japan Center for Fundamental EducationOkayama University of Science1-1Ridai-choKita-kuOkayama CityOkayama 700-0005Japan 

出 版 物：《Geoscience Frontiers》 (地学前缘（英文版）)

年 卷 期：2024年第15卷第3期

页      面：31-49页

核心收录：

学科分类：081803[工学-地质工程] 08[工学] 0818[工学-地质资源与地质工程] 

基　　金：Shoko Science Co.Ltd.This work was partly supported by a grant from the Ministry of Education,Culture,Sports,Science and Technology,Japan(No.17H04858,19H01081,19K14828,20H01991,23K13205) the Fukada Grant-in-Aid(2021)of Fukada Geological Institute(No.135) 

主　　题：Carbonate diagenesis Francevillian Group LA-ICP-MS Seawater composition Y/Ho fractionation 

摘      要：The Paleoproterozoic Francevillian Group in the eastern Gabonese Republic has been recently attracting increasing attention because it includes distinctive macroscopic structures interpreted as eukaryotic ***,its depositional setting and associated redox conditions need to be clearly *** clarify these,petrological studies and rare earth element(REE)abundances of carbonate rocks of the Francevillian Group in the Lastoursville basin were determined with ICP-MS coupled with a laser ablation sampling *** microscopic observations indicate that dolostones in this basin underwent the complicated diagenetic history,including sparitization,decomposition of organic matter,reduction of ferromanganese oxides,silicification,and later *** dolostones of lower Francevillian B(FB)Formation show heterogeneous textures formed by alterations during *** the alterations,changes of REE abundances and degrees of positive Y anomalies appear to have *** indicates that REE signatures in carbonate rocks can vary during *** high Mn contents in the dolostones of upper FB Formation were derived from the reduction of ferromanganese oxides in *** signatures of REE abundance in dolostones can be explained by the mixing of seawater and ferromanganese oxide *** that sense,the dolostones inherited the trace element characteristics of precursor ferromanganese oxides even after the diagenesis.Y/Ho values of the most primary parts of each sample exceed 33,the newly determined threshold value for marine carbonate rocks based on our *** magnitude of the La anomaly values also falls within the range of that of Holocene reefal *** indicate that a precursor of the dolostone of the Francevillian Group was deposited in a marine *** addition,presence of Ce anomalies in the upper FB Formation suggests that the Paleoproterozoic ocean was oxidized to such an ex