A global comparison of V_(p),V_(s),and V_(p)/V_(s) structures of the mantle lithosphere beneath major cratons  

作　　者：Ehsan BARZGAR Fenglin NIU Shunping PEI 

机构地区：[1]State Key Laboratory of Petroleum Resources and Prospecting,Unconventional Petroleum Research Institute,China University of Petroleum,Beijing 102249,China [2]Department of Earth,Environmental and Planetary Sciences,Rice University,Houston 77005,Texas,USA [3]State Key Laboratory of Tibetan Plateau Earth System and Resources Environment,Institute of Tibetan Plateau Research,Chinese Academy of Sciences,Beijing 100101,China

出　　处：《Science China Earth Sciences》2023年第3期492-504,共13页中国科学（地球科学英文版）

基　　金：supported by the National Natural Science Foundation of China (Grant Nos. 41630209, U2039203, 42130306)。

摘　　要：Cratons formed due to the specific melting regime of the primitive mantle with elevated mantle temperature during Archean.However,each craton has undergone a distinct evolution history,and some have lost their stability.To investigate to what degree cratons in comparison with one another have been modified from their analogous initial form,we employed Sn-Pn differential(PSn) traveltimes to derive Vp/Vsratio,which is thought to be related to Mg# of the uppermantle.We assessed Pn,Sn,and PSn data using three datasets based on epicentral distance:(1) 2°–12°,(2) 2°–7°,and(3) 7°–12°.The results suggest that most cratons show comparable seismic properties with high velocities and low Vp/Vsratio,implying a highly depleted uppermost mantle that resembles the original residue from the partial melt extraction of the primitive mantle during the Archean.Conversely,the Eastern North China Craton(ENCC) displays the lowest P-and S-wave velocities,and noticeable high Vp/Vsratios in all datasets,implying a systematic difference with other cratons.This observation suggests a scenario of total removal of the depleted Archean mantle lithosphere beneath the ENCC.In contrast,the Ordos Block located at the western part of the North China Craton(WNCC) shows velocities and Vp/Vsratio comparable with those of the typical cratons,suggesting that it has still maintained its Archean mantle lithosphere.The Wyoming Craton has a high Vp/Vsratio similar to that of the ENCC and a high Pwave velocity comparable to that of the typical cratons.These features suggest that the Archean mantle lithosphere has been significantly modified rather than totally removed and replaced by a younger fertile mantle.The Indian Craton presents a low Vp/Vsratio and comparatively high velocities at shallow parts of the mantle lithosphere but a high Vp/Vsratio at deeper parts similar to that of the ENCC,suggesting a partial modification of the Indian Craton at deeper parts.

关 键 词：CRATON Craton modification Mantle lithosphere North China Craton Wyoming Craton Indian Craton Vp/Vs ratio Seismic velocity 

分 类 号：P315[天文地球—地震学]