『Abstract
　This paper provides an overview of regional geochemical mapping using stream sediments from central and south-western Nigeria. A total of 1569 stream sediment samples were collected and 54 major and trace elements determined by ICP-MS and Au, Pd and Pt by fire assay. Multivariate statistical techniques (e.g., correlation analysis and principal factor analysis) were used to explore the data, following appropriate data transformation, to understand the data structure, investigate underlying processes controlling spatial geochemical variability and identify element associations Major geochemical variations are controlled by source geology and provenance, as well as chemical weathering and winnowing processes, more subtle variations are a result of land use and contamination from anthropogenic activity.
　This work has identified placer deposits of potential economic importance for Au, REE, Ta, Nb, U and Pt, as well as other primary metal deposits. Areas of higher As and Cr (＞2 mg/kg and ＞70 mg/kg respectively) are associated with Mesozoic and younger coastal sediments in SW Nigeria. High stream sediment Zr concentrations (mean＞0.2%), from proximal zircons derived from weathering of basement rocks, have important implications for sample preparation and subsequent analysis due to interferences. Associated heavy minerals enriched in high field strength elements, and notably rare earths, may also have important implications for understanding magmatic processes within the basement terrain of West Africa.
　This study provides important new background/baseline geochemical values for common geological domains in Nigeria (which extend across other parts of West Africa) for assessment of contamination from urban/industrial land use changes and mining activities. Regional stream sediment mapping is also able to provide important new information with applications across a number of sectors including agriculture, health, land use and planning.』

１. Introduction
2. Study areas: geology, mineralisation, climate and land use
　2.1. Geology
　2.2. Known mineralisation in the study areas
　2.3. Climate and land use
3. Methodology
　3.1. Field sampling programme
　3.2. Sample preparation and analyses
　3.3. Quality control
　3.4. Data analysis
4. Results
　4.1. Stream-sediment geochemistry
　4.2. Mineralogy
5. Discussion
　5.1. Stream-sediment geochemistry and mineralogy of major geological domains
　　5.1.1. Distribution of the major elements
　　5.1.2. Distribution of trace elements
　　5.1.3. Mineralogy
　　5.1.4. Stream-sediment texture
　5.2. Spatial variation in multivariate geochemical signatures
　5.3. Geochemical variations in relation to land use, potential contamination and environmental guidelines
　5.4. Implications for geochemical mapping in West Africa
6. Conclusions
Acknowledgements
Appendix A. Supplementary material
References