Distribution study of ore-sourced elements from a long drill-core in a loess-covered area

Abstract

This research aims at studying the vertical distribution modes of geochemical elements in the covering layer above a deposit.Seventy-eight samples were sequentially collected from a vertical loess drill core above Diyanqinamo Mo-deposit, which were equally separated in 1m's intervals.Each of the samples was screened into grains of grade 20, 40, 80, 120, 160, 200 and 200+ meshes to get 78×7 graded samples.The contents of 32 elements in each graded sample were measured by a handheld X-ray fluorescence analyzer to form a 78×7×32 dataset.Firstly, since the grain grades as attributes in a panel dataset are in orders, we regarded this dataset as a new type one and named it as Ordered-Attributes Panel Data (OAPD).Secondly, the non-parametric Friedman test was used to explore the correlation of the contents of the elements with both the distancefrom the ore and the grain grade separately.It turned out that among the 32 elements Mo, Zr, Sr, Rb, Th, Pb, Zn, Ni, Co, Fe, Mn, V, Ti, Sc, Ca, K, Ba, Cs, Te, Sb, Sn and Cd are correlated with both the distance and the grade.Then, varying coefficient-models were applied to the 22 elements to get the variation modes of the regression coefficients, reflecting the change rates of the contents with respect to the grain grades.At last, the variation modes were sketched and classified.