Understanding the tectonic framework of orogenic belts involv-ing both ancient continental basement blocks and fault-contact younger metasedimentary rocks is a fundamental scientific issue in plate tectonic studies[1,2].Continental fragments have been widely reported in current ocean and subduction systems[1],such as the South China Sea,Philippine Sea,Central Mediterranean Sea in Europe,and Scotia Sea in South America.They are inevitably involved in young subduction zones and mixed with younger tec-tonically accreted rocks,which may affect the characteristics of the plate tectonics[3].This type of tectonic organization raises the possibility that the sporadically distributed Precambrian rocks equate to a unified Precambrian block.Therefore,it is essential to develop a method for identifying continental fragments in mature orogens.The key point is that a unified Precambrian block would not mix with younger metasedimentary rocks but that a fore-arc subduction-accretion complex can include both Precambrian frag-ments and younger accreted materials.The Dunhuang Orogenic Belt(DOB),located in northwestern China(Text S1 and Fig.S1 online),is an excellent case illustrating how continental fragments are identified in orogenic belts[4].Chaotic tectonic mixing between ancient(late Neoarchean-Paleoproterozoic)continental basement fragments and surrounding young(Neoproterozoic-Pal eozoic)metasedimentary concomitant rocks was recognized,sug-gesting that the old continental components were involved as"building blocks"during the Paleozoic subduction-accretionary history.

Qian W.L.Zhang;Yichao Chen;Zhen M.G.Li;Jiahui Liu;Qing Zhang;Chunming Wu

College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China;Institute of Geomechanics,Chinese Academy of Geological Sciences,Beijing 100081,China

科学通报（英文版）

[1]Qian W.L.Zhang;Yichao Chen;Zhen M.G.Li;Jiahui Liu;Qing Zhang;Chunming Wu-.Identification of continental fragments in orogen:an example from Dunhuang Orogenic Belt,northwestern China)[J].科学通报（英文版）,2022(15):1549-1552

involv,tonically,eozoic

Identification,continental,fragments,example,from,Dunhuang,Orogenic,Belt,northwestern,China,Understanding,framework,orogenic,belts,both,ancient,basement,blocks,fault,contact,younger,metasedimentary,rocks,fundamental,scientific,issue,plate,studies,Continental,have,been,widely,reported,current,ocean,subduction,systems,such,South,Sea,Philippine,Central,Mediterranean,Europe,Scotia,America,They,are,inevitably,involved,zones,mixed,accreted,which,may,affect,characteristics,tectonics,This,type,organization,raises,possibility,that,sporadically,distributed,Precambrian,equate,unified,Therefore,essential,develop,method,identifying,mature,orogens,key,point,would,not,complex,can,include,materials,DOB,located,Text,S1,Fig,online,excellent,case,illustrating,how,identified,Chaotic,mixing,between,Neoarchean,Paleoproterozoic,surrounding,Neoproterozoic,concomitant,was,recognized,sug,gesting,old,components,were,building,during,Paleozoic,accretionary,history

0.525213