Idades U-Pb de zirc?￡o detr?-tico da sequ?ancia metassedimentar superior na regi?￡o do Greenstone Belt de Guarinos, Goi??s

摘要

At the north portion of the Archean Block of Goi??s occur two greenstone belts (Guarinos and Pilar de Goi??s) covered??by a younger metasedimentary sequence, attributed by different authors to the Arax?? Group and by other to the Serra da??Mesa/Serra Dourada and, by other writers, simply as Mesoproterozoic Sequence. Although there are lithostratigraphic??similarities between the Arax?? and Serra da Mesa groups, most recent studies have shown that the evolution of basins??and their sedimentation ages have peculiarities that differentiate one from the other. This work presents geochronological??data of U-Pb on detrital zircon grains obtained by laser ablation method (LA-MC-ICP-MS) in quartzite samples.??The youngest zircon has the age of 1405 ?± 10 Ma, marking the maximum depositional age and indicating source area.??The samples have a higher frequency of Paleoproterozoic zircons, between 1796 and 2472 Ma and the oldest populations??of mesoneoarchean age between 2672 and 3112 Ma. Whereas the Paleoproterozoic to Archean zircons can be derived??from the rocks that form the Archean Block of Goi??s, the mesoproterozoic source is still uncertain, perhaps this source??can be related to the Goi??s Tin Province rocks.