Journal of

GEOsciences

  (Formerly Journal of the Czech Geological Society)

Original Paper

Viktor Valtr, Pavel Hanžl

Geophysical cross-section through the Bogd fault system in the area of the Chandman rupture, SW Mongolia

Journal of Geosciences, volume 53 (2008), issue 2, 193 - 200

DOI: http://doi.org/10.3190/jgeosci.023

The internal structure of the Bogd fault, which is one of the largest intra-continental faults in Asia, was studied using the geophysical methods of very low frequencies, vertical electrical sounding and induced polarization vertical sounding. The geophysical profile was situated on the eastern foothill of the Chandman Khayrkhan Uul (SW Mongolia) near the branching of the Chandman rupture, recently seismically active western part of the Bogd fault zone. Geophysical measurements confirmed several sub-parallel faults that are steeply dipping to the south. An imbricated structure inside the fault zone and anastomosing trends of mylonitic zones were revealed by the orientation of the low resistivity zones. The most distinct anomalies indicating the fault zone were localised in mylonitized graphitic limestones, which were preferentially involved in the structure of the fault. The orientations of geophysical anomalies together with geological and structural data from the surface indicate steep thrusting of the southern block over the northern one, accompanying the dominating strike-slip component of the movement along the Chandman rupture. Geometry of faults delimiting the Chandman Khayrkhan Uul, strong asymmetrical morphology of mountain and relics of the Quaternary gravels in its upper part indicate rapid uplift of the range during the Cenozoic in the restraining bend.