GEOGRAPHIC VARIATIONS OF MAJOR ELEMENTS FOR PERIDOTITIC XENOLITHS IN RELATION TO CRUST/LITHOSPHERE AGE AND THICKNESS IN EASTERN CHINA
Weimi CHEN Xin M.A.Menzies 1)(Changsha Institute of Geotectonics, Academia Sinica, Changsha, Hunan, 410013, P.R.China) 2)(Department of Geology, Royal Holloway, University of London. Egham, Surrey TW20 OEX, UK)
Cenozoic basalt-borne peridotitic xenoliths in eastern China point to the presence of thin, hot and fertile lower lithosphere. The Archaean and post-Archaean terrains are underlain by chemically similar mantle, but more fertile lithosphere mantle exists beneath the thin crust (35 km). However, pre-Mesozoic kimberlites and their xenoliths and xenocrysts reveal that the thick, cold and refractory lithosphere mantle enriched in incompatible components was present. The contrast between the recent and Paleozoic lithosphere mantle in chemistry, thickness and thermal state in eastern China implies that the paleo-lithosphere mantle was destructed and replaced by MORB+OIB mantle to different degrees. The recent lithosphere mantle in eastern China may be a mixture of occanic mantle and old cratonic mantle remnants.