Datasets generated for O'Mara et al. (2024), Constraining Plio-Pleistocene shifts in Northwest African hydroclimate, ecosystem distributions, and marine productivity: new paleo-records across the Mid-Pleistocene Transition. <i>Paleoceanography and Paleoclimatology</i>.

Organic and inorganic geochemical paleo-proxy measurements from marine sediment core MD03-2705 taken from the Northwest African margin. New samples dating to the Mid-Pleistocene Transition (1.1 – 1.0 Ma) are presented here. Data include plant-wax hydrogen (dD) and carbon (d13C) isotopes; plant-wax concentrations; and constant flux (extraterrestrial 3He) normalized estimates of mass accumulation rates of bulk sediment, dust, opal, and calcium carbonate. Plant-wax concentrations were made via gas chromatography-mass spectrometry at the Lamont-Doherty Earth Observatory (LDEO) Organic Geochemistry Lab using an Agilent 7890A GC coupled to an Agilent 5975C MS, plant-wax isotope measurements were made at the LDEO Stable Isotope Lab using A Thermo Delta V Advantage isotope ratio mass spectrometer coupled to a Thermo Trace GC Ultra and Isolink through a ConFlo IV, helium isotope measurements were made in the LDEO Noble Gas Lab using a MAP-215 mass spectrometer, and carbonate and opal fractions were measured at the LDEO Noble Gas Lab and the Bradtmiller Lab at Macalester College using coulometry and alkaline extraction and molybdate blue spectrophotometry respectively.<b>File descriptions</b>: inorg_table.xlsx includes the inorganic geochemical measurements of helium isotopes, and mass accumulation rates of multiple sedimentary components of each sample.org_iso_table.xlsx includes the isotope measurements of plant-wax n-alkane carbon and hydrogen isotopes (including ice-volume corrections for hydrogen), calculated landscape fraction C4 plants, and precipitation hydrogen isotopes estimated from the C31 n-alkane.alk_conc_table.xlsx includes the concentration of C25-C35 odd chain length n-alkanes in micrograms per gram of dry sediment.All data tables have core depth (cm) and associated age estimates for each sample. event_metadata.xlsx includes the core metadata. meas_metadata.xlsx includes units for each variable across the three data tables.

本数据集包含取自西北非陆缘的海洋沉积物岩芯MD03-2705的有机与无机地球化学古代用指标测量数据。本次公开的新样品年代覆盖中更新世过渡期（Mid-Pleistocene Transition, 1.1–1.0 Ma）。数据集涵盖植物蜡氢同位素（δD）、碳同位素（δ¹³C）比值，植物蜡浓度，以及以恒定通量（地外³He, extraterrestrial ³He）归一化得到的块状沉积物、粉尘、蛋白石与碳酸钙的质量堆积速率估算值。
植物蜡浓度检测于拉蒙特-多尔蒂地球观测站（Lamont-Doherty Earth Observatory, LDEO）有机地球化学实验室完成，采用安捷伦7890A气相色谱仪（Agilent 7890A GC）联用安捷伦5975C质谱仪（Agilent 5975C MS）；植物蜡同位素检测于LDEO稳定同位素实验室完成，采用Thermo Delta V Advantage同位素比率质谱仪，通过ConFlo IV接口联用Thermo Trace GC Ultra与Isolink装置；氦同位素检测于LDEO稀有气体实验室完成，采用MAP-215质谱仪；碳酸盐与蛋白石组分的检测分别于LDEO稀有气体实验室及马卡莱斯特学院（Macalester College）布莱特米勒实验室（Bradtmiller Lab）完成，前者采用库仑滴定法，后者采用碱萃取-钼蓝分光光度法。
<b>文件说明</b>：inorg_table.xlsx 包含各样品的氦同位素无机地球化学测量数据与多种沉积组分的质量堆积速率数据；org_iso_table.xlsx 包含植物蜡正构烷烃（n-alkane）碳、氢同位素（含氢同位素冰体积校正）的测量数据、计算得到的地表C4植物占比，以及基于C31正构烷烃估算的降水氢同位素比值；alk_conc_table.xlsx 包含C25–C35奇数链长正构烷烃的浓度数据，单位为微克每克干沉积物。所有数据表均包含岩芯深度（cm）与各样品的对应年代估算值；event_metadata.xlsx 包含该岩芯的元数据；meas_metadata.xlsx 包含上述三个数据表中各变量的单位信息。

搜集汇总

背景与挑战

背景概述

该数据集包含西北非洲边缘海洋沉积岩芯MD03-2705的有机和无机地球化学古代理测量，覆盖Mid-Pleistocene Transition时期（约1.1-1.0百万年前），用于研究水文气候、生态系统和海洋生产力的变化。数据主要包括植物蜡同位素、浓度以及沉积物成分的质量积累率，以Excel文件形式提供，并附有核心元数据和单位信息。