The Significance Of Granite In Puna Plateau,Argentina

The South American Andean metallogenic belt is an important part of the Circum-Pacific metallogenic belt and is also a focus point concerned by international geologists.In recent years,South America has become an important area for global mineral resources exploration and investment,and is also the main destination for many Chinese mining companies to“Go globally”.In this study,granite from the Puna Plateau（Tanque,Cobres and Padreao）in Argentina was selected for petrology,geochemistry（Major element、Trace elements and Pb,Sr,and Nd isotopes）,and zircon U-Pb chronology,combined with the history of geological evolution,the following understandings were obtained:The Paleozoic granite can be divided into two stages.The early granite is a calcium-alkaline series,which is rich in silicon（70.13%-74.26%）,high K₂O+Na₂O（6.26%-9.52%）,and rich in K,Rb,Th,and loss Nb,P,Ti peraluminum A-type granite,formed in the back-arc extensional background of the Famatinian cycle,the zircon U-Pb age is measured to be 489 Ma;the late granite can be divided into two types,one is high-calcium-calcium alkaline series,Is a low-silicon（69.32%-69.96%）,relatively rich in K₂O+Na₂O（6.3%-6.8%）and rich in K,Rb,Th,loss of Nb,P,Ti peraluminum S-type granite;one is Calcium-alkaline series,which are silicon-rich（71.58%-73.28%）,low K₂O+Na₂O（5.52%-5.76%）and subaluminum S-type granite rich in K,Rb,Th,and depleting Nb,P,Ti,The zircon U-Pb age is measured to be 466 Ma,which was formed in the squeezing tectonic setting associated with the subduction of the precordillera terrane or Cuyania terrane during the Famatinian cycle.Mesozoic granites are peralkaline A-type granites,which are rich in silicon（72.8%）,high in K₂O+Na₂O（9.37%）,and rich in Nb and Sm.The zircon U-Pb age is measured to be 124 Ma and formed in the back-arc extensional background and may be related to the opening of the Atlantic Ocean and the movement of tectonic activities to the west of the South American Plate.The Cenozoic granite porphyry veins are I type granites,characterized by silicon-rich（73.43%）,high K₂O+Na₂O（8.13%）,K-rich,Rb,Th,depleted Nb,P,Ti,the zircon U-Pb age is measured to be 10.3 Ma,formed in the background related to the subduction of the Pacific plate.Since the Paleozoic,the study area has experienced multi-phase tectonic activities and thickening of the crust.Since the Meso-Cenozoic,the structural system has changed from orogeny to non-orogenic intraplate activity,which has led to the formation of structures different from typical Andean porphyry deposits background.