Problems of Engineering Seismology: article

Аnnotation: To study the mineral composition of the crack shear surface in the core from the well in the seismically active area of Koyna-Warna, Western India, associated with reservoir triggered seismicity, infrared reflection and transmission spectroscopy methods were used. Methods of conducting a complex of experimental studies of mineral composition of the crack shear surfaces in the rocks are described. The performed experiments demonstrated the wide possibilities of these methods and allowed us to obtain new results on shear cracks that are important for further studies on earthquake physics. It is established that the crack shear surface of studied sample is a three-layer structure. The upper layer contains only glauconite nanocrystals. Under it, there is a layer that contains crystals of calcite and montmorillonite in addition to glauconite. Total thickness of these layers is about 600 µm. Below these layers is the host rock containing calcite, dolomite and glauconite. The number of illite-smectite layers in glauconite nanocrystals was determined. Upper layer contains nanocrystals consisting of ≈30 layers. In the second layer, crystals of this mineral contain ≈25 layers. Finally, glauconite nanocrystals in the host rock consist of ≈20 layers.