Was Triassic Continental Subduction Solely Responsible for the Generation of Mesozoic Mafic Magmas and Mantle Source Enrichment in the Dabie-Sulu Orogen?
作者单位：Department of Earth SciencesNational Taiwan Normal University
会议名称：《中国科学院地质与地球物理研究所2003学术年会》
会议日期：2003年
学科分类：070902[理学-地球化学] 0709[理学-地质学] 07[理学]
基 金：supported by grants from the Major State Basic Research Development Program of China(G1999075502) National Natural Science Foundation(No.40002006) of China “Funds for Hundred Outstanding Talents Plan”from the Chinese Academy of Sciences
摘 要：Mesozoic mafic rocks in the Dable-Sulu orogen(DSO) are enriched in large-ion lithophile elements (LILE,e.g.,Rb,K,Sr,Ba),relatively depleted in high-field strength elements(HFSE,e.g., Nl),Ta,P,Ti),and have strongly fractionated rare-earth elements(REE) and highlyenrichedSr-Nd isotope ***are-typegeochemical signatures have been generally ascribed to mantle source enrichment beneath the DSO by fluids/melts released from deeply subducted Triassic continental crust,i.e.,part of the South Cliina block(SCB).However,contemporaneous mafic rocks are widespread in the North China block(NCR) and possess similar elemental and Sr-Nd isotopic characteristics. Given that most of the NCB mafic rocks were emplaced at a considerable distance from the DSO,their are-type geochemical features are unlikely to have been caused by Triassic continental ***,we argue that subduction of the SCB is a potential,but not necessarily the only,mechanism responsible for mantle enrichment beneath the *** propose instead that the lithospheric mantle beneath the DSO and NCB was enriched prior to Triassic subduction,and that generation of the mafic rocks in both regions was due to a shared,regional-scale geological event, which we attribute lo post-collisional delamination of the mantle lilhosphere.