On the ancient volcanism and isostatic movements significance for the formation of the Badzhal Ridge topography (Lower Priamurye)

Abstract

The isostatic component of the total Cenozoic uplift of the Badzhal Ridge has been identified and approximately estimated. The ridge was chosen because the Cenozoic denudational lowering magnitude could be defined with sufficient reliability. Volume of cut-off rocks (defined by geomorphological technique) is about 1/3 of the primary prism of igneous rocks which the ridge consists of; the volume corresponds to load reduction of 180 kg/Km² at the area of 15 000 km². Hence the isostatic uplift of the ridge compensating the denudational unload has been calculated to be equal to 560-600 m during the Cenozoic stage, the calculation using the formula by E. N. Lustig (1957). The conclusion has been done about the importance of the isostatic factor in morphostructures movements of young folded regions and its everywhere distribution, the tectonic (neotectonic) active movements being of local manifestation.