Abstract: The Zhangmajing uranium deposit is the largest volcanic-related hydrothermal uranium deposit in northern China, which
wall-rock alteration was widely developed. The distribution of pyrite mineralization in this deposit is relatively limited, but closely 
related to mineralization. In order to study the relationship between pyrite transformation and uranium mineralization, molybdenum
mineralization, the main trace element analysis of the pyrite-altered rock in Zhangmajing was carried out. This paper used the mass
balance migration method using Yb as the inactive component to calculate its component migration with the Grant formula. The
geochemical characteristics of the rocks showed that the content of TFeO in pyrite altered rock was extremely high, ranging from
11.24% to 24.57% (average 18.45%), of which Fe2O3 content was 10.78%~25.25% (average 18.64%), FeO content was 1.43%~1.90%
(average 1.69% ). The average Fe2O3/FeO ratio was 10.99, which might be affected by subsequent oxidation. The slope of the
iso-concentration line of the pyrite-altered rock was less than 1 in the Isocon diagram, indicating that the whole component had been
taken in. The taken-in component was mainly the large amount of TFeO (131 times), ore-forming element including Mo (884 times), Pb
(11 times), U (4.9 times), V (2.8 times), Ta (0.44 times), Cu (0.64 times), and alkali metal Na2O (0.45 times), and Cd (424 times), Bi (13
times), etc. In addition, the alkali metal Li (-0.73), K2O (-0.17), ore-forming elements Zn (-0.38), Cr (-0.37), and Eu (-0.58), Sc
(-0.25) and other components were taken out. Among them, SiO2 was slightly reduced (-0.03), and the taken-in Mo content was much
higher than U which had relatively consistent migration characteristics with those of molybdenum ore. It could be concluded that t
pyrite altered rocks were closely molybdenum mineralization.

Key words: pyritization, element transfer, mass balance transfer calculations；Zhangmajing U-Mo deposit