Геотектоническая позиция и строение Спахиевского рудного поля

Abstract

Based on analysis of the physical parameters of rocks and the distribution of geophysical fields, many new data on the structure and geotectonic position of Spahievo ore field were obtained. A complex of geological and geophysical information was interpreted using physicogeological modelling. The results show that the tectonic position of the ore field is controlled mainly by the deep-seated Ardino-Spahievo and Novakovo-Pilaševo fault zones and the Momcilgrad-Spahievoregional fault. The tectonic knot, formed at their intersection, is a source structure marked by concentration of intensive magnetic anomalies of different sign. A large part of these anomalies are related to abundant comagmatic bodies both exposed on the surface (Sârnica, Mezarlâksârt, Pilaševo, Karaman) and cryptointrusive (Garno Bryastovo, Susam, Ramadan). Their magnetic properties enable to evaluate the depth, form and sometimes the approximate composition of the bodies. The area studied shows a block-disintegrated and faulted pre-Paleogene basement, dipping westsouthwest towards Borovica Depression. Depending on the distribution of the geophysical fields, the structural, magmatic and metallogenic features, three large mesoblocks may be divided: Borovica (I), Pilaševo (II) and Sârnica (Ill). Each mesoblock contains characteristic mineralization – rare-metal, gold-polymetallic and polymetallic, respectively. The 1ead-zinc ore mineralizations are related to an uplifted block of the basement, located in the central part of the eastern segment and formed by the intersection of Ardino-Spahievo and Novakovo-Pilaševo deep-seated fault zones. The knot areas of the regional deep zones control the origin of polyformational mineralization.