USE OF DIFFERENT FRACTURE ANALYSIS METHODS FOR TECTONIC STRESS FIELDS RECONSTRUCTION (ON EXAMPLE OF THE TAZHERAN INTRUSIVE MASSIF IN PRIBAIKALIE)

The Purpose of the paper is to carry out a complex analysis of fracturing and compare the results of two fundamentally different reconstruction methods of tectonic stress fields on the basis of geological and structural data of the Tazheran site in Pribaikalie. Methods. The study employs a new approach to the paragenetic analysis of statistical measurements of «mute» fracturing, which allows to restore the stressed state of a local rock volume and determine its belonging to the fault zone of a certain morphogenetic type and orientation. The second reconstruction method of stress fields is a kinematic method based on the analysis of fracture displacement vectors. Results. The analysis of 22 mass measurements of fracture attitude (100 joints each) and 158 measurements of slickensides at 16 observation points has been carried out. We have obtained 70 solutions of the paragenetic method and 26 solutions of the kinematic method on local stress fields. Fracture parageneses were formed in the fields of compression, shear and strike-slip in approximately equal amounts. The traces of displacements are more developed in strike-slip fields. A comparison of results for each observation point has showed that most of kinematic solutions (21 of 26) have a paragenetic solution similar in type and orientation for the stress field of the first or second order. Conclusions. The reconstruction results of local stress fields by two methods are comparable and in general complement and partially confirm each other. The identical stress fields restored by different methods are presumably referred to one stage. The other mainly paragenetic solutions indicate stress fields in the early development stages of small fault zones within the site. A complex use of paragenetic and kinematic methods is recommended.

reconstruction of a stress field, fractures, fault zone, joint system, fracture paragenesis, slickenside, slickenlines

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