Очаговые структуры Восточных Родоп – геофизическая характеристика и металлогеническое значение

Abstract

Chamber structures of Paleogene magmatism are a characteristic element of the structure or collisional depressions in the East Rhodopes. The following larger chamber structures are distinguished as circular heterogeneities of a 'different' type and class in the geophysical fields: Borovitsa, Zvezdel-Krumovgrad, Madzharovo and Lozen. Except for the Zvezdel-Krumovgrad structure the others coincide, in their larger part, with gravitation minima or occupy parts of them like Madzharovo caldera. In the magnetic field they are an ensemble of local anomalies, circular in shape and of different polarlties. In accord with the magnetic field morphology, the Zveztlel-Krumovgrad siructure consists of two partially overlapping chamber structures. Besides that, within their range sharply enhanced concentrations of potassium-40 – have been established. The petrophysical analysis and interpretation of geophysical fields show that the chamber structures lie in tectonic nodes - areas of crossing of depth magma-conduit faults. They are characterized by enhanced endogenous activity – high tectonic dynamics, intensive magmatic hydrothermal metasomatic activity. Mineralization often develops against this background. Lead-zinc deposits and ore fields determining the metallogenic nature of the East Rhodopes are directly connected with the chamber structures considered above. Geophysical data show that certain industrial deposits practically lie within the area of intermediate magmatites and even in the immediate proximity of their largest centres. All this corroborates the concept about the lead-zinc mineralization most probably being in a paragenetic relation with intermediate Upper Eocene and Oligocene collision magmatism.