Superimposed Mineralization Model of Paleozoic Porphyry Copper Deposits in Xinjiang
Chen Huayong
Wu Chao
Xiao Bing
Wang Yunfeng
Abstract：With the advance of green energy transformation in the 21st century,the demand for copper has surged dramatically and porphyry copper deposits as the main suppliers of global copper resources have been paid great attention from both academic and industrial communities.Although a set of classic models have been established for Cenozoic porphyry copper deposits,the porphyry copper deposits located at Paleozoic Central Asian Orogenic Belt exhibit unique characteristics and their genesis mechanisms are not fully understood.Taking important porphyry copper deposits in Xinjiang as research objects,this study reveals that these deposits generally experienced multiple magmatic activities with time spanning up to 100-200 Ma and often underwent superimposed and/or modification mineralization stages after porphyry mineralization.For example,the Tuwu-Yandong deposit has mineral assemblages of anhydrite,chalcopyrite,calcite,and chlorite after porphyry mineralization;the Yuhai-Sanchakou mining area exhibits post-porphyry veins of epidote,quartz,chlorite,zeolite,and calcite;and the Halasu copper belt shows late alteration and mineralization with copper-bearing sulfide veins and argillic alteration.Fluid inclusion studies further confirm that new fluid systems would overprint on the hydrothermal fluid system in the porphyry stage.Based on these observations,it proposes a new superimposed mineralization model of modification for Paleozoic porphyry copper deposits in Xinjiang.In the early stage of island arc evolution,pre-mineralization magmatic activities may form unmineralized alterations in the mining areas such as early sodic-calcic alteration and epidote alteration at the Halasu belt.With the maturity of the island arc,tectonic triggers such as flat subduction facilitated high oxygen fugacity,water-rich magmatic activities which partly have adakite-like geochemical features and formed the porphyry-type mineralization and alteration in the mining areas such as diorite porphyry in Tuwu-Yandong and diorite porphyry and granodiorite porphyry at Halasu.Further tectonic evolution including change of subduction polarity or postcollisional asthenospheric upwelling led to new magmatic hydrothermal activities superimposed on preexisting porphyry-type mineralization and alteration.Moreover,post-mineralization tectonic metamorphism may also introduce new mineralizing materials or cause remobilization of preexisting ores.The aforementioned models underscore the importance of specific tectonic or magmatic activities that may superimpose on pre-existing porphyry mineralization systems in long-lived arcs with sustained multistage magmatic activities.These activities,beyond the classic types of porphyry mineralization alteration,require special attention due to their exploration potential to introduce new mineralizing components.
Keywords：Paleozoic porphyry copper depositsuperimposed mineralizationXinjiangCentral Asian Orogenic Beltgeochemistrydeposits
Publication Date：2025-11-30
Online Publishing Date：2025-12-15(First online date of this platform, not the publication date of the document)
Pages：18( 4177-4194 )