Abstract:

The “lithostatic pressure” model of underground rocks posits that the primary source of lithostatic stress in underground rocks is the gravitational force exerted by the overlying rocks.This model assumes that the rock mass is internally static and that no shear stress is present.The premise of the “lithostatic pressure” model is that rocks are in a relatively stable environment over a long period.However, the Earth is a dynamic and non-steady system, with different tectonic environments controlling the formation and evolution of rocks and subjecting them to various dynamic mechanisms.The application of the “lithostatic pressure” model is limited, especially in compressional tectonic environments where horizontal tectonic stress can cause deviations from “lithostatic pressure”.The stress in underground rocks can be composed of two parts: gravitational stress and tectonic stress.The formation and evolution of deep underground minerals are controlled by the temperature and pressure of the formation environment.Tectonic dynamics is the main factor controlling the internal pressure of solid minerals, while also being influenced by the plasticity, viscosity, and strength of the solid rocks, as well as the pressure of fluids in the pores and cracks within the rocks.The process of ore formation is influenced by the tectonic environment and constrained by temperature and pressure conditions.Therefore, the ore-forming process needs to be analyzed in conjunction with the specific tectonic environment.The internal pore fluid in the rocks undergoes corresponding changes with the evolution of tectonic activity.When the permeability of the rock pores and cracks is impeded during tectonic the evolution, a certain degree of pore fluid overpressure will develop.The pore fluid overpressure and differential stress at the same depth vary under different tectonic environments, with overpressure in compressive tectonic environments being higher than in extensional environments.“Tectonic additional lithostatic pressure” plays an important role in the study of deep geological structure, the tectonic control of rocks and ores, and deep engineering geology.

Key words: tectonic ore-forming, lithostatic pressure model, tectonic stress combined with gravitational stress, tectonic additional lithostatic pressure, effective stress