Crustal Thickness Evolution Controls the Formation of Porphyry Cu Deposits in Collisional Orogens:An Example from Central Tethys  

作　　者：WANG Xuhui LANG Xinghai WU Changyi DENG Yulin Robert MORITZ 

机构地区：[1]College of Earth and Planetary Sciences,Chengdu University of Technology,Chengdu 610059,China [2]Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring(Central South University),Ministry of Education,Changsha 410083,China [3]State Key Laboratory of Continental Dynamics,Northwest University,Xi’an 710069,China [4]Department of Earth Sciences,University of Geneva,Geneva 1205,Switzerland

出　　处：《Acta Geologica Sinica(English Edition)》2025年第2期522-531,共10页地质学报(英文版)

基　　金：funded by the National Key R&D Program of China(Grant No.2022YFC2905000);the NSFC(Grant No.42230813);the Opening Foundation of State Key Laboratory of Continental Dynamics,Northwest University(Grant No.23LCD12);the Opening Foundation of the Key Laboratory of Continental Dynamics of Ministry of Natural Resources(Grant No.J2408);the Sichuan Province Natural Science Foundation(Grant Nos.2024NSFSC1954,2025ZNSFSC1196);the Open Research Fund Program of Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring(Central South University),Ministry of Education(11300-502401003);the Everest Scientific Research Program of Chengdu University of Technology(Grant No.2024ZF11407).

摘　　要：The key factor that controls the genesis of porphyry Cu deposits(PCDs)in collisional orogens remains a debated topic.This study employs whole-rock La/Yb proxies to quantitatively constrain the spatial and temporal variations in crustal thickness of the South Armenian-Iranian magmatic belt(SAIMB)within the Zagros orogen(central Tethys region)since the Eocene.Our results show that rapid crustal thickening occurred first in the NW section of the SAIMB at~35 Ma,then propagated southeastward into the central and SE sections at~25 Ma and 20 Ma,respectively,indicating that the Arabia-Eurasia collision was diachronous.The formation of the large and giant collision-related PCDs in the SAIMB might have been controlled by the collision process because they developed first in the NW section of the SAIMB and subsequently propagated southeastward into the central and SE sections.More importantly,crustal thickness mapping shows that the PCDs are preferentially developed in the thickened crust areas(>50 km).Our findings propose that thickened crust is critical for the formation of the PCDs in collisional orogens by promoting Fe^(2+)-rich minerals as a fractionating phase,driving magmatic auto-oxidation and releasing Cu into the magmas.The Cu is then partitioned into magmatic fluids,sustaining the porphyry systems.Furthermore,our research highlights that the thickened crust hosting PCDs was characterized by a previously thinner crust(<40 km),where magmas had low oxygen fugacity due to the absence of the auto-oxidation process.Consequently,chalcophile elements(e.g.,Cu)efficiently separated from the melt through sulfide segregation,forming large Cu-bearing lower-crustal cumulates.These cumulates can be mobilized with an increase in oxygen fugacity,incorporating into subsequent porphyry mineralization.We thus propose that the crustal thickness evolution over time controls the formation of the PCDs in collisional orogens.There are two essential stages in the collision-related PCDs formation:the first is high-flux magmatism in the thi

关 键 词：porphyry Cu deposit crustal thickness pre-enrichment Arabia–Eurasia collision Tethyan metallogenic belt 

分 类 号：P618.41[天文地球—矿床学]