During Carboniferous time,tremendous juvenile arc crust was formed in the southern Central Asian Orogenic Belt(CAOB),although its origin remains unclear.Herein,we presented zircon U-Pb-Hf and whole-rock geochemical and Sr-Nd isotopic data for a suite of volcanic and pyroclastic rocks from the Khan-Bogd area in southern Mongolia.These Carboniferous pyroclastic rocks generally have some early Paleozoic zircons,probably derived from the granitic and sedimentary rocks of the Lake Zone and the Gobi-Altai Zone to the north,indicative of a continental arc nature.In addition,they have a main zircon U-Pb age of ca.370-330 Ma,positive Hf and Nd isotopes,and mafic-intermediate arc affinity,similar to the coeval arc magmatism.Moreover,the pyroclastic rocks of the northern area have more mafic and older volcanic components with depositional time(ca.350-370 Ma;Visean and Bashkirian stages)earlier than that in the southern area(mainly ca.350-315 Ma;Serpukhovian and Bashkirian stages).Combining a preexisting northward subduction supported by the available magnetotelluric data with a slab rollback model of the main oceanic basin of the Paleo-Asian Ocean(PAO)during Carboniferous and Triassic times,we infer that the Carboniferous arc magmatism was probably derived from a backarc ocean triggered by slab rollback.Thus,the juvenile arc volcanism of Mongolia,together with other areas(e.g.,Junggar)in the southern CAOB,represented a significant lateral accretion that terminated after the Carboniferous due to a significant contraction of the PAO.

Hai Zhou;Guochun Zhao;Yigui Han;Donghai Zhang;Meng Wang;Xianzhi Pei;Narantsetseg Tserendash;Qian Zhao;Enkh-Orshikh Orsoo

School of Earth Science and Resources,Chang'an University,Xi'an 710054,China;State Key Laboratory of Continental Dynamics,Department of Geology,Northwest University,Xi'an 710069,China;Department of Earth Sciences,the University of Hong Kong,Hong Kong 999077,China;Institute of Paleontology and Geology,Mongolian Academy of Sciences,Ulaanbaatar 15160,Mongolia;Key Laboratory of Orogenic Belt and Crustal Evolution,Ministry of Education,School of Earth and Space Sciences,Peking University,Beijing 100871,China;Marco Polo Limited Liability Company,Ulaanbaatar 15141,Mongolia

科学通报（英文版）

[1]Hai Zhou;Guochun Zhao;Yigui Han;Donghai Zhang;Meng Wang;Xianzhi Pei;Narantsetseg Tserendash;Qian Zhao;Enkh-Orshikh Orsoo-.Carboniferous slab-retreating subduction of backarc oceans:the final large-scale lateral accretion of the southern Central Asian Orogenic Belt)[J].科学通报（英文版）,2022(13):1388-1398

backarc,pyroclastic,Bogd,Visean,Bashkirian,Serpukhovian

Carboniferous,slab,retreating,subduction,oceans,final,large,scale,lateral,accretion,southern,Central,Asian,Orogenic,Belt,During,tremendous,juvenile,crust,was,formed,CAOB,although,its,origin,remains,unclear,Herein,we,Pb,Hf,whole,geochemical,Sr,Nd,isotopic,data,suite,volcanic,rocks,from,Khan,Mongolia,These,generally,have,some,early,Paleozoic,zircons,probably,derived,granitic,sedimentary,Lake,Zone,Gobi,Altai,indicative,continental,nature,In,addition,they,Ma,positive,isotopes,mafic,intermediate,affinity,similar,coeval,magmatism,Moreover,northern,more,older,components,depositional,stages,earlier,than,that,mainly,Combining,preexisting,northward,supported,by,available,magnetotelluric,rollback,model,oceanic,basin,Ocean,PAO,during,Triassic,times,infer,triggered,Thus,volcanism,together,other,areas,Junggar,represented,significant,terminated,after,due,contraction

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