The characteristics of vertical primary halo zoning in the Louli gold deposit, Handan City, Hebei Province

The Louli gold deposit is located on the northern side of Hongshan alkalic complex, and the host rock of the orebody is the volcanic tufa. This is the first ore deposit of such type found in volcanic tufa in the southern segment of the Taihang Mountain, and its metallogenic regularity and deep metallogenic prospect evaluation are of guiding significance for delineating potential prospective areas and increasing mineral resources. Based on the regional mineralization regularity and geological characteristics, the authors systematically collected rock samples in 2 drill holes, and used Gregorians zonality index method and generalized contrast value method to compute and determine vertical zoning sequence of indicator elements. The results show that different calculation methods may produce somewhat different element orders, but the active stages of hydrothermal fluid and spatial superposition mode of halos are identical. The computed result of two drill holes shows the obvious coexistence of frontal halo and tail halo and axial zoning characteristics. The active process of hydrothermal fluid was analyzed based on the trace elements geochemical parameter axial variation. The results obtained show that the vertical zoning of two drill holes are made up of two stage hydrothermal circulation, suggesting that the formation of gold deposit is of multi-stage characteristics.