Geological evolution and important mineralization of S?o Francisco Craton in Brazil
This paper is Geological evolution and important mineralization of São Francisco Craton in Brazil.[Objective]This paper aims to sort out and construct the tectonic evolution process of the São Francisco Craton in Brazil,outline the coupling relationship with its metallogenic geological setting and ore deposit series,and identify the temporal and spatial distribution of typical deposits,in order to serve the theory of craton evolution and ore formation.[Methods]Based on the field geological survey conducted in China-Brazil cooperation,and combined with the zircon U-Pb and Sm-Nd isotope chronology of basement Archean gneiss and Proterozoic detrital rocks of the São Francisco Craton in Brazil,this paper summarizes the major geological tectonic evolution events and important mineralization processes of the São Francisco Craton.[Results]Four important geological evolution process of the São Francisco Craton were preliminarily constructed:(1)Before 3.5 Ga,the formation of paleo continental nuclei and microcontinental masses,between 3.3～2.9 Ga and 2.8～2.5 Ga,the four paleo continental cores of Archean Gavião block,Sobradinho block,Serrinha block,Jequié block in the north and the nearly circular paleo continental nuclei in the south collided,stitched and proliferated the greenstone-arc magma belt to form a stable cratonic mass.(2)2.3～1.9 Ga Paleoproterozoic Pan-Amazonian orogenic arc magmatic activity.(3)1.78～1.20 Ga basement uplift,rift stage,forming a large number of basic dikes and non-orogenic magmatism activities and other transformation processes to complete the thickening of landmass and cratonization.(4)Forming 6 active orogenic belts such as Brazilian orogenic belt,the Neoproterozoic craton margin underwent the transformation of the Brasilia/Pan-African movement(0.64～0.54 Ga).São Francisco craton has formed 4 important mineralization and corresponding deposit metallogenic series:(1)Archean mineralization(＞2.5 Ga)formed metamorphic volcano-sedimentary metallogenic series such as greenstone-type gold deposits and Lake Superior-type iron deposits(BIF).(2)The early-middle Paleoproterozoic mineralization(2.5～1.8 Ga)formed Cu-Ni-Co sulfide deposits,Pb-Zn volcanogenic massive sulfide(VMS)deposits,and iron oxide-copper-gold(IOCG)deposits related to(super)mafic rocks.(3)Mesoproterozoic-Consolidated mineralization(1.8～1.0 Ga)formed series of deposits such as V-Ti-Fe deposits related to its intracontinental(marginal)rifts,Nb-Ta and Cu deposits related to non-orogenic magmatism.(4)The Neoproterozoic mineralization(1.0～0.54 Ga)formed Fe-Mn,alluvial tin and P deposits,including(alluvial)diamond placer deposits related to paleo continental margin-neritic sedimentary environment.Key words:São Francisco Craton;tectonic evolution;metallogenesis;metallogenic series;Brazil.[Conclusions]Four important geological evolution processes of the São Francisco Craton in Brazil have been constructed,and four important metallogenic periods have been divided accordingly.
São Francisco Cratontectonic evolutionmetallogenesismetallogenic seriesBrazil
万方数据
维普
