U-Pb data of carbonate and apatite embedded within Fe-Mn crusts and associated foraminifera fossils from the Rio Grande Rise, Southwestern Atlantic

This dataset consists of U-Pb geochronological measurements of carbonate and phosphate phases from ferromanganese (Fe-Mn) crust samples dredged from the Rio Grande Rise (RGR) in the South Atlantic. The samples were collected during the 2011 research expeditions of the Geological Survey of Brazil (SGB-CPRM) and the Interministerial Committee for Marine Resources (CIRM) aboard the RV Marion Dufresne, as part of the PROERG and PROAREA programs. Among the recovered materials, three samples (ML77, ML67, and DC25A) were selected for in situ U-Pb dating using Laser Ablation Multi-Collector Inductively Coupled Plasma Mass Spectrometry (LA-MC-ICPMS) at the University of Brasília. U-Pb ages were obtained for foraminifera fossils (Discocyclina sp., Nummulites sp., and Globorotalia sp.) and for the carbonate and apatite matrix of the samples. Measurements were performed using a Thermo Finningan Neptune XT MC-ICP-MS coupled to a Teledyne Analyte Excite 193 nm laser ablation system, following the analytical protocol described in Brito et al. (2024). Data reduction was conducted using the UComPbine DRS protocol, with corrections for blank subtraction, crater fractionation, and mass fractionation normalized to Walnut Canyon calcite and NIST SRM 614. Ages were calculated using IsoplotR and are reported as lower intercept ²³⁸U/²⁰⁶Pb values anchored on their respective initial ²⁰⁷Pb/²⁰⁶Pb composition. Final age uncertainties are presented at the 2σ confidence interval, incorporating both analytical and systematic uncertainties. This dataset provides new constraints on the geochronology of Fe-Mn crusts in the RGR, contributing to the understanding of Fe-Mn crusts precipitation, diagenetic processes, and paleoceanographic evolution in the South Atlantic.

本数据集包含南大西洋里奥格兰德海隆（Rio Grande Rise, RGR）采集的铁锰（Fe-Mn）结壳样本中碳酸盐相和磷酸盐相的U-Pb地质年代学测量数据（U-Pb geochronological measurements）。这些样本由巴西地质调查局（Geological Survey of Brazil, SGB-CPRM）和海洋资源部际委员会（Interministerial Committee for Marine Resources, CIRM）于2011年在“马里昂·迪弗雷纳”号科考船（RV Marion Dufresne）上开展的研究考察中采集，属于PROERG和PROAREA项目的一部分。在回收的样品中，三个样本（ML77、ML67和DC25A）被选中，由巴西利亚大学采用激光剥蚀多接收电感耦合等离子体质谱法（Laser Ablation Multi-Collector Inductively Coupled Plasma Mass Spectrometry，LA-MC-ICPMS）进行原位U-Pb定年（in situ U-Pb dating）。测量使用赛默飞世尔科技（Thermo Finningan）Neptune XT型MC-ICP-MS联用Teledyne Analyte Excite 193 nm激光剥蚀系统完成，遵循Brito等人（2024）所述的分析方案。数据处理采用UComPbine DRS协议，包含空白扣除（blank subtraction）、坑分馏（crater fractionation）及质量分馏（mass fractionation）校正，并归一化至Walnut Canyon方解石与NIST SRM 614标准物质。年龄通过IsoplotR软件计算，报告为基于各自初始²⁰⁷Pb/²⁰⁶Pb组成的下交点²³⁸U/²⁰⁶Pb值。最终年龄不确定度以2σ置信区间表示，涵盖分析不确定度与系统不确定度。本数据集为RGR区域铁锰（Fe-Mn）结壳的地质年代学提供了新约束，有助于深化对南大西洋铁锰结壳沉淀过程、成岩作用（diagenetic processes）及古海洋演化（paleoceanographic evolution）的理解。