n-Alkane concentrations and molecular indices (CPI, ACL, Paq) from Holocene marine sediment cores MDBT 557 and MDBT 561 (southern Brazilian shelf)

This dataset presents concentrations of long-chain n-alkanes (nC25–nC33) and derived molecular indices, including Carbon Preference Index (CPI), Average Chain Length (ACL), and Paq, from Holocene marine sediment cores MDBT 557 and MDBT 561, recovered from the southern Brazilian continental shelf. Lipid biomarkers were extracted using organic solvents, purified by column chromatography, and quantified by gas chromatography with flame ionization detection (GC-FID), with surrogate standards used to assess analytical recovery. These data characterize variations in terrigenous organic matter input, vegetation-related signals, and hydrological conditions affecting the continental margin during the Holocene.本数据集涵盖从巴西南部大陆架获取的全新世海相沉积岩芯MDBT 557与MDBT 561的长链正构烷烃（nC25–nC33）浓度及其衍生分子指标，其中衍生指标包括碳优势指数（Carbon Preference Index, CPI）、平均链长（Average Chain Length, ACL）以及Paq。本次研究采用有机溶剂萃取脂质生物标志物，经柱层析法纯化后，借助带火焰离子化检测器的气相色谱（GC-FID）完成定量分析，并通过替代标准品评估分析回收率。该数据集可用于表征全新世期间影响巴西大陆边缘的陆源有机质输入、植被相关信号及水文条件的变化规律。