Analysis and modelling of airborne geophysical data in the Phetchabun Volcanic Belt, northern part of Central Thailand

Abstract

In this thesis, new re-processed airborne geophysical data together with relevant current field verification as well as previous geochronological, geochemical and geological investigations lead to the clarification of the complex structures and tectonic evolution in Phetchabun volcanic terrane covered by thick Cenozoic deposits. During the Permo-Carboniferous period, the original elongate units in central domain corresponding to intrusive igneous bodies may have occurred in Late Carboniferous volcanic arc and association with subduction of the Nakhonthai oceanic plate beneath the Indochina continental plate. Subsequently, during the Permo-Triassic period, the elongate units reflect the subduction again as evidence by brittle-ductile structure which is deformed in represent of fold and thrust zone in central domain besides the mesothermal gold deposit in this zone. The structural configuration of this stage is characterized by east-west compressional stress. Ring units of Permo-Triassic volcanic arc centers and the presence of circular units representing equigranular intrusive bodies are occurred from the result of eastward subduction.On the contrary, the east-west extension stress during the Triassic period is inferred to be contemporaneous diachronous with the subsidence in eastern domain of volcanic arc and deposited the epithermal gold which contemporaneous with the uplift of the preliminary Khorat basin in northern 2 sub-domain. Consequently, the spot units representing shallow porphyritic intrusive bodies occurred along the subsidenced fault zone during this stage.