XRD, major and trace geochemical data of sedimentary rocks from borehole cores in the Middle Pleistocene - Upper Pleistocene strata of Yaohu Lake area in the Qaidam Basin

The relative error of measured mineral contents is ±2%, the repeat scanning deviation of 2θ ≤ 0.01°, and the confidence level of phase identification is ≥95%. Combined with Rietveld whole‑pattern refinement, the mass fraction of each mineral phase can be accurately acquired to systematically characterize the assemblages of evaporite minerals, detrital minerals and clay minerals, and effectively reconstruct sediment provenance and the precipitation evolution of saline minerals in the lake basin.

For geochemical analyses, 44 sediment samples were collected from 1–239 m depth of the same drill core. Major elements (SiO₂, Na₂O, K₂O, MgO, TiO₂, Al₂O₃, CaO, Fe₂O₃) and selected trace elements including Sc, Cr, Co and Zr were determined using a Thermo Fisher ARL Perform'x X‑ray fluorescence spectrometer (XRF). Samples were prepared by pressed powder pellets prior to measurement, and the analytical procedures strictly followed Chinese national standards GB/T 14506.28‑2010 and GB/T 14506.34‑2019.

For other trace elements, a mixed‑acid digestion method was adopted: powder samples were completely digested with nitric, hydrochloric, hydrofluoric and perchloric acids, followed by heating to remove acids. After cooling, the solution was diluted to 100 mL in a volumetric flask with ultrapure water and homogenized for test. U, Th, Rb, Cs and the full suite of rare earth elements (La, Ce, Pr, Nd, etc.) were measured by a PerkinElmer NexIon 2000 inductively coupled plasma mass spectrometer (ICP‑MS), while Li concentrations were determined using an Agilent 5900 inductively coupled plasma optical emission spectrometer (ICP‑OES).

This integrated dataset contains detailed mineral assemblages and comprehensive major‑trace geochemical proxies, which can systematically reveal the nature of source rocks, catchment chemical weathering intensity and elemental migration and enrichment patterns. It precisely constrains the weathering‑transport‑sedimentation evolution of the Yahu Lake catchment and paleoenvironmental changes of the salt lake, and provides robust mineralogical and geochemical data support for understanding salt formation evolution, material transport mechanisms and regional paleoclimatic changes in the Yahu Lake area of the Qaidam Basin since the Middle Pleistocene.