Temporal and spatial distribution of Mesozoic mafic magmatism in the North China Craton and implications for secular lithospheric evolution
会议名称：《中国科学院地质与地球物理研究所2007学术年会》
会议日期：2008年
学科分类：070902[理学-地球化学] 0709[理学-地质学] 07[理学]
基 金：funded by grants from the Chinese Academy of Sciences(KZCX1-07) the Natural Science Foundation of China(40225009,40534022)
摘 要：Mesozoic mafic magmatism in the North China Craton shows a clear temporal and spatial *** mafic volcanism occurred dominantly in the northern and southern margins of the craton,with episodic eruptions from Early Jurassic to Late Cretaceous *** contrast, Mesozoic mafic magmatism,which produced gabbroic to dioritic intrusive complexes, occurred in the centre of the craton in areas such as the Taihang Mountains and the Luzhong region,and all the complexes were intruded at almost the same time in the Early Cretaceous. This temporal and spatial distribution of Mesozoic mafic magmatism shows a strong heterogeneity of the Late Mesozoic lithospheric mantle beneath the North China Craton and a secular evolution of the lithospheric mantle beneath *** lithospheric mantle beneath the Luzhong region is slightly isotopically enriched;that beneath the Taihang Mountains has an EMI character in Sr and Nd isotopic features(Sr/Sr) = 0.7050-0.7066;εNd(t))= -17 to -10);and it possesses EM2-like characteristics.(Sr/Sr) up to 0.7114) beneath the Luxi-Jiaodong *** general enrichment suggests that the Mesozoic lithospheric mantle was distinctive compared with Palaeozoic and Cenozoic *** secular evolution of this variably enriched Mesozoic lithospheric mantle requires a considerable modification,transformation and reconstruction of the lithospheric mantle beneath the craton in Late Mesozoic *** elemental and isotopic compositions and the coherence of the lithospheric changes with the formation of circum-craton orogenic mobile belts indicate that these rapid lithospheric changes and corresponding lithospheric thinning were tectonically related to the multiple subduction and subsequent collisions of circumcraton *** melting of subducted oceanic and continental crustal materials produced silicic melts that migrated up and reacted with lithospheric peridotites to generate more fertile lithospheric mantle(‘wet’ low-Mg peridotites pl