An overview of hydrodynamic studies of mineralization

Abstract

Fluid flow is an integral part of hydrothermal mineralization, and its analysis and characterization constitute an important part of a mineralization model. The hydrodynamic study of mineralization deals with analyzing the driving forces, fluid pressure regimes, fluid flow rate and direction, and their relationships with localization of mineralization. This paper reviews the principles and methods of hydrodynamic studies of mineralization, and discusses their significance and limitations for ore deposit studies and mineral exploration. The driving forces of fluid flow may be related to fluid overpressure, topographic relief, tectonic deformation, and fluid density change due to heating or salinity variation, depending on specific geologic environments and mineralization processes. The study methods may be classified into three types, megascopic (field) observations, microscopic analyses, and numerical modeling. Megascopic features indicative of significantly overpressured (especially lithostatic or supralithostatic) fluid systems include horizontal veins, sand injection dikes, and hydraulic breccias. Microscopic studies, especially microthermometry of fluid inclusions and combined stress analysis and microthermometry of fluid inclusion planes (FIPs) can provide important information about fluid temperature, pressure, and fluid-structural relationships, thus constraining fluid flow models. Numerical modeling can be carried out to solve partial differential equations governing fluid flow, heat transfer, rock deformation and chemical reactions, in order to simulate the distribution of fluid pressure, temperature, fluid flow rate and direction, and mineral precipitation or dissolution in 2D or 3D space and through time. The results of hydrodynamic studies of mineralization can enhance our understanding of the formation processes of hydrothermal deposits, and can be used directly or indirectly in mineral exploration. ª 2011, China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V. All rights reserved.

Fluid inclusions and isotopic characteristics of the Jiawula Pb–Zn–Ag deposit, Inner Mongolia, China

“…The mechanisms leading to the precipitation of metals from Cl -and/or HS -complexes include the following (Barnes, 1979;Ramboz et al, 1982;Robb, 2004;Chi and Xue, 2011): (1) temperature decrease, (2) pressure decrease, (3) phase separation, (4) fluid mixing/dilution, and (5) fluid/rock interaction causing pH and Eh shifts.…”

Relationships between Hydrodynamics of Mineralization and Tectonic Settings

“…The driving forces of geologic fluid flow include topographic relief, rock deformation (including sediment compaction), and fluid density variation (especially those related to geothermal gradients, thermal anomalies, and salinity anomalies) (Chi and Xue, 2011). These factors, as well as rock permeabilities that affect fluid flow velocities, are intimately related to tectonic settings.…”

Growth, destruction and volcanic facies architecture of three volcanic centres in the Miocene Uşak–Güre basin, western Turkey: Subaqueous–subaerial volcanism in a lacustrine setting

“…The development of hydraulic breccia indicates high fluid pressure (most likely lithostatic or supralithostatic) and low differential stress (e.g. Chi and Xue, 2011). This area was also affected by faint multi-stage hydrothermal alterations such as particularly the potassic and argillic and rarely propylitic alterations.…”