Investigating rock permeability effects on mineralization locations of the Changba-Lijiagou Pb-Zn deposit, Gansu, China: Modelling of ore-forming mechanisms through the dual length-scale approach

Comparison of the computationally simulated Pb distribution pattern (Right column) with the observed Pb distribution (Left column) • To computationally simulate the ore-forming process in the Changba-Lijiagou deposit. • To determine the deposit model boundary conditions in a scientific way • To identify the controlling mineralization mechanism in the Changba-Lijiagou deposit. • To investigate the permeability effect on the location of the Changba-Lijiagou deposit. The Pb-Zn deposit at Changba-Lijiagou is located in the ore cluster of Xihe-Chengxian (OCXC), Gansu Province, China. In the OCXC, several giant Pb-Zn and Au deposits were already discovered. Although the extensive studies, which are commonly based on the traditional geoscience method, were carried out for understanding the hydrothermal system related to the Pb-Zn deposit at Changba-Lijiagou, ore formation processes related to this deposit have not been, so far, fully understood and scientifically confirmed. In this study, the finite element method (FEM) based approach of using dual length-scale models, which are called the deposit model and the regional model, is utilized to computationally simulate the formation processes related to the Pb-Zn deposit at Changba-Lijiagou. Particular attention is paid on investigating the rock permeability effects on the mineralization locations of the Pb-Zn deposit at Changba-Lijiagou. Main outcomes obtained from this study have proven that: (1) the primary dynamic mechanism is the pore-fluid convection, which controls the formation of the Pb-Zn deposit at Changba-Lijiagou; (2) even though regional model rock permeabilities may affect the computationally simulated grade of the Pb-Zn deposit at Changba-Lijiagou, they do not affect the computationally simulated location of the Pb-Zn deposit at Changba-Lijiagou; (3) the FEM based approach of using dual length-scale models is quite useful for computationally simulating the formation mechanism of the Pb-Zn deposit at Changba-Lijiagou.