REGIONAL STRUCTURAL‐TECTONIC ZONING OF THE UPPER CRUST OF TRANSBAIKALIA BASED ON SEISMOGRAVITATIONAL DATA ALONG REFERENCE PROFILE 1‐SB

Abstract

Upper crust fault and fold patterns are studied with an innovative approach of controlled‐source seismic refraction profiling integrated with gravity data. The potentiality of the conventional method based on refrac‐ tion/wide‐angle reflection traveltimes, which has been so far applied to plane‐parallel layered earth, is extended onto deformed crust with lateral and vertical inhomogeneities due to advanced processing technologies. Performance of the approach is tested on data of the 1‐SB transect that traverses geologically studied areas and provides good refer‐ ence. Upper crust features revealed from seismic data agree with known geological structures, this indicating the basic applicability of refraction surveys to tectonically complex areas with 7 to 10 km wide low‐angle dipping fault zones between blocks marked by velocity anomalies to depths of 4–6 km. Joint interpretation of refraction and gravity patterns becomes possible within the limits of a seismic‐gravity model in which both are characterized by seismic‐ density and seismic acceleration values of the same dimension.

Keywords

• refraction seismics
• seismic‐gravity modelling
• tectonic division
• upper crust’ folded area