Abundance And Distribution Of Lead In Outcropping Rocks And Catchment Sediments In Mainland China

The abundance and distribution of geochemical elements in outcropping rocks and sediments can be used as a comparative basis for the study of geochemical behavior in exploration geochemistry and environmental geochemistry,and it is of wide significance in geoscience research.In this paper,the abundance,distribution and geological significance of lead in outcropping rocks,as well as the distribution,baseline value and background value of lead in catchment sediments,are systematically studied by using the data obtained from China Geochemical Baseline projectintiated in 2008-2014 in mainland China.The following conclusions can be drawn:1)This paper has established the database of lead abundance of rocks in whole China and eight primary tectonic units.2)The lead abundance of outcropping rocks in mainland China is 14.8mg/kg,which is calculated with area weighting method.The result is lower than lead aboundance in upper continental crust,because of large area of carbonate rocks with low lead content are existed in outcropping curst.3)Variation of lead in stratum of different era is related to super-continent cycle.Lead jumped from 13.3mg/kg to 21.7mg/kg in early Paleozoic era maybe caused by NOE.4)The lead abundance in catchment sediments in mainland China is 22.1mg/kg.The remarkable characteristic of lead spatial distribution is the decreasing trend from southeast to northwest.The spatial differentiation characteristics of are determined by combined factors of climate,geomorphology,geological background,mineralization,and human activities.Lead5)The baseline and background values of lead in catchment sediments are established in 8 primary geotectonic units,32 primary basins,10 geographical landscape zones,17 agrotype areas,9 plain areas,and 31 provinces in China.6)The enrichment coefficients of the dispersion flow,the ratio of lead content in sediments to that in rocks,in different provinces and geographical landscape area in China are calculated,which provides basic data for studying geochemical cycle in the Critical Zone.