Abstract: Mud volcano is located in the mudstone area and is formed under the special geological conditions. There are more than 90 mud volcanic eruptions near the poplar ditch in Wusu City, Xinjiang, which is the largest mud volcano group found in China. Mud volcano is a rare natural geologic landscape in nature. Research on rare mud volcanic group in Xinjiang has drawn more and more attention both at home and abroad. It is essential to study the elemental composition and content of volcanic mud for evaluation and utilization of this nature resource. Energy dispersive X-ray fluorescence analysis(EDXRF)was used for the analysis of composition and element content of Xinjiang Wusu Tianshan volcano mud soil samples. 60 kinds of elements were detected and their accurate element content was determined. Eight heavy metals Cd, As, Cu, Hg, Pb, Cr, Zn, Ni were chosen as evaluation factors, and were analyzed by using single index evaluation and Nemerow index method. Results show that the content of Cd, As and Cu element reached secondary standard of soil quality evaluation; Hg, Pb, Cr, Zn and Ni element content reached first standard of soil quality evaluation. The soil element contents in volcanic mud soil were compared with those in soils of other regions in Xinjiang as well as other provinces in the arid zone. The comparing results show that Mn, Fe, Cu content, as well as alkali metal Li, Na and K concentration in lahar were relatively higher. Elemental background value was analyzed according to geological features and the impact of soluble salt content. The environmental quality status of volcano mud soil samples and cause of the formation of higher content elements in lahar were analyzed. The comprehensive analysis of the mud volcano samples has not been previously reported in literatures.

Key words: volcanic mud, Wusu, composition and content, comparison of heavy metals