The application of studies on fluid inclusion planes and fracture systems in the reconstruction of fracturing history of granitoid rocks II

Abstract

In this paper the results of studies on fluid inclusion planes, fractal analyses studies on mineralized fractures, and the
calculated paleo-permeability of the Mórágy Granite Formation (Mecsek Mountains, Hungary) are presented. Studies
on the fluid inclusion planes of quartz from granite and pegmatite revealed differences between regional and local fluid
mobilization events. Based on the combination of field observations on faults and joints, with orientation of fluid
inclusion planes and fluid inclusion microthermometry results, one regional and three local hydrothermal systems were
identified. The common stress orientations which have driven fracture developments were NW–SE and NE–SW. The
calculated palaeo-permeability for carbonate veins always fell short in comparison to values calculated for fluid inclusion
planes in the quartz of the host rock. This affirms that the fluid percolation properties of rocks are mainly determined by
the micro-fracture networks. Fractal analysis has confirmed the fractal properties of the carbonate vein systems and
proved that those veins are clustered. Calculation of fractal dimensions revealed the connectivity differences of the vein
systems and helped to explain the contradictory paleo-permeability tendencies calculated from fluid inclusion planes and
carbonate veins among various outcrops. The investigations that were carried out suggest that a combination of studies
on fluid inclusion planes with field observations on mineralized veins, joints and faults constitues a suitable tool for
solving structural geological problems in non-stratified rocks such as granite.