Recycling of Paleo-Asian Ocean carbonates and its influence on the lithospheric composition of the North China Craton  

作　　者：Yongsheng LIU Chunfei CHEN Detao HE La ZHANG Kaizhang YU 

机构地区：[1]State Key Laboratory of Geological Processes and Mineral Resources,School of Earth Sciences,China University of Geosciences,Wuhan 430074,China [2]Department of Earth and Environmental Sciences,Macquarie University,North Ryde 2109,Australia

出　　处：《Science China Earth Sciences》2021年第8期1346-1362,共17页中国科学（地球科学英文版）

基　　金：supported by the Key R&D Program of China(Grant No.2019YFA0708400);the National Natural Science Foundation of China(Grant No.41530211);the Special Fund of the State Key Laboratory of Geological Processes and Mineral Resources(Grant No.MSFGPMR01)。

摘　　要：The deep carbon cycle,which plays a critical role in mantle evolution and Earth habitability,is closely linked to the recycling of carbonate-bearing rocks through subduction.Marine carbonates are subducted to different depths during the closure of oceanic basins,thus carry important signatures of the disappeared oceanic basins.Petrological and geochemical features of the Hannuoba carbonatites in the northern North China Craton indicate that they were formed by melting of limestone subducted to mantle depths.Here,we show that detrital zircons carried by these carbonatites have a broad spectrum of U-Pb ages from Precambrian to Phanerozoic.Precambrian age peaks are at~2.5 Ga,2.1–2.3 Ga,1.8–2.0 Ga,~1.65 Ga,1.3–1.4 Ga,~1.1 Ga,0.91–0.94 Ga,0.74–0.81 Ga,and 0.62–0.63 Ga,respectively.The recorded age peaks are different from those in the northern North China Craton and thus preclude an origin of crustal contamination.Nevertheless,the Precambrian age spectra are compatible with those of the Xingmeng Orogen in the southeastern Central Asian Orogenic Belt.Furthermore,the significantly positiveεHf(t)values of 7.7–13.5 for the 300–373 Ma zircons are similar to those in the Xingmeng Orogen but different from those in the northern North China Craton.All these features suggest that the limestone precursor for the Hannuoba carbonatites was originated from the Paleo-Asian Ocean,and its deposition time was not earlier than 300 Ma.This indicates that the PaleoAsian Ocean still existed in the late Carboniferous to early Permian.The widespread distribution of metamorphic carbonates in the Central Asian Orogenic Belt indicates that there may have been widespread sedimentary carbonates in the Paleo-Asian Ocean.A large amount of sedimentary carbonates was probably carried into mantle during subduction of the Paleo-Asian oceanic slab,which significantly modified the chemical and physical properties of the lithospheric mantle.

关 键 词：North China Craton LITHOSPHERE Paleo-Asian Ocean SUBDUCTION Deep carbon cycle Zircon geochronology 

分 类 号：P59[天文地球—地球化学] P736.2[天文地球—地质学]