Global geochemical mapping and its implementation in the Asia–Pacific region

Abstract “IGCP” Projects 259 (International Geochemical Mapping) and 360 (Global Geochemical Baseline) under the aegis of UNESCO's International Geochemical Correlation Program made recommendations for standardizing geochemical mapping protocols and for conducting a wide-spaced sampling of the Earth's land surface based on a Global Reference Network of approximately 5000 160×160 km cells. A pilot study has been conducted throughout China during which these recommendations were implemented. During the pilot study, 500 floodplain samples representing drainage basins ranging in area from 1000 to 6000 km 2 were collected throughout China and analyzed. The widely spaced sampling used for the pilot study was compared to the very dense sampling (× million samplings of sediment for all of China) used for China's Regional Geochemical National Reconnaissance Program. The geochemical maps generated from the wide-spaced sampling are strikingly similar to those generated from data based on the detailed sampling. Such low density floodplain sampling presents a relatively low-cost way to get a quick overview of the geochemistry of a large area of the Earth's surface. The implementation of this project in the Asia–Pacific region and the problems encountered are discussed in the present paper.