Melting of subducting oceanic lithosphere and associated melt-mantle interactions in convergent plate margins require specific geodynamic environment that allows the oceanic slab to be abnormally heated.Here we focus on the Early Mesozoic mafic rocks and granite porphyry,which provide insights into slab melting processes associated with final closure of the Paleo-Asian Ocean.The granite porphyry samples are calc-alkaline and distinguished by high Sr contents,strong depletion of heavy rare earth elements,resulting in high(La/Yb)N and Sr/Y ratios,and negligible Eu anomalies.Based on their high Na2O and MgO,low K2O contents,positive εHf(t)and εNd(t)and low(87Sr/86Sr)i values,we propose that the granite porphyry was likely derived from partial melting of subducting Paleo-Asian oceanic crust.The Nb-enriched mafic rocks are enriched in Rb,Th,U,Pb and K,and depleted in Nb,Ta,Ba,P and Ti,corrob-orating a subduction-related origin.Their heterogeneous Sr-Nd-Hf-O isotopic compositions and other geochemical features suggest that they were likely derived from partial melting of peridotitic mantle wedge interacted with oceanic slab-derived adakitic melts.Trace element and isotope modeling results and elevated zircon δ18O values suggest variable subducting sediments input into the mantle wedge,dominated by terrigenous sediments.Synthesizing the widely-developed bimodal rock associations,con-jugated dikes,thermal metamorphism,tectonic characteristics,paleomagnetic constraints,and paleogeo-graphical evidence along the Solonke-Changchun suture zone,we identify a slab window triggered by slab break-off,which accounts for slab melting and formation of the Nb-enriched mafic rocks and asso-ciated adakitic granite porphyry in southeastern Central Asian Orogenic Belt.

Yan Jing;Wenchun Ge;M.Santosh;Yu Dong;Hao Yang;Zheng Ji;Junhui Bi;Hongying Zhou;Dehe Xing

College of Earth Sciences,Jilin University,Changchun 130061,China;Key Laboratory of Mineral Resources Evaluation in Northeast Asia,Ministry of Land and Resources of China,Changchun 130026,China;School of Earth Sciences and Resources,China University of Geosciences Beijing,Beijing 100083,China;Department of Earth Science,University of Adelaide,Australia;Tianjin Center,China Geological Survey,Tianjin 300170,China;Shenyang Center,China Geological Survey,Shenyang 110034,China

地学前缘（英文版）

[1]Yan Jing;Wenchun Ge;M.Santosh;Yu Dong;Hao Yang;Zheng Ji;Junhui Bi;Hongying Zhou;Dehe Xing-.Generation of Nb-enriched mafic rocks and associated adakitic rocks from the southeastern Central Asian Orogenic Belt:Evidence of crust-mantle interaction)[J].地学前缘（英文版）,2022(02):255-274

corrob,orating,peridotitic,paleogeo,Solonke

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