Abstract

This data article describes a multi-element soil-geochemistry dataset collected over a six-week field campaign (2 June-9 July 2025) across the La Negra Formation outcrop in the Antofagasta Region of northern Chile. The dataset comprises 101 primary Atacama Desert soil samples, 15 systematic field duplicates and 7 outcrop rock pulps collected in the field distributed across two parallel north-south transects with an average along-transect spacing of similar to 10 km between consecutive points. The transects span six sectors in the communes of Tocopilla, Antofagasta and Taltal. Every sample was prepared following the Chilean national protocol for soil studies: air-dried, sieved to the < 2 mm fine-earth fraction, and pulverised for analysis, so the dataset characterises the conventional fine-earth fraction of the soils. Each sample was analysed at AGS An & aacute;lisis Geoqu & iacute;micos (Coquimbo, Chile; lab batch CL25-7655) under a single, internally consistent protocol. The AGS panel covers 62 analytes per sample, reported as aqua-regia-extractable concentrations quantified by ICP-MS; because aqua regia is a partial digestion, values for elements hosted in resistant silicate phases are lower bounds on total contents. Six elements (Mn, Co, Ni, Cu, Zn, Pb) were re-analysed by atomic-absorption spectroscopy (AAS) on the same pulps at the Laboratorio de Geoqu & iacute;mica, Universidad Cat & oacute;lica del Norte (UCN, Antofagasta, Chile), providing an independent inter-method and inter-laboratory check on the ICP-MS values for these environmentally relevant trace metals. Quality assurance and quality control includes per-element duplicate R2, the fraction of samples above the method detection limit, an inter-method relative-difference table, per-element soil-versus-rock comparisons and a four-level per-element quality flag (11 of the 62 analytes classify as high-quality, 40 as acceptable, 6 as low-reproducibility and 5 as low-detection) that identifies which analytes support quantitative reuse. We describe the sampling design, the laboratory workflow and the QA/QC outcomes. The dataset is released as a set of well-documented CSV and GeoJSON files under CC-BY-4.0 and provides a single-laboratory, single-protocol baseline of fine-earth soil geochemistry along the two sampled transect corridors of the La Negra Formation, against which future surveys of the soils of the Atacama Desert can be compared.