Mesozoic shoshonitic intrusives in the Yangchun Basin, western Guangdong, and their tectonic significance:II . Trace elements and Sr- Nd isotopes

摘要: Trace elements and Sr- Nd isotopic data are presented for the Mesozoic intrusives in Yangchun Basin, western Guangdong. The Mashan monzo- diorites characterized by strong enrichment of K, Sr LREE, nearly chondritic compositions with (87Sr/86Sr)i≈ 0.704 6 ande Nd(t)≈ 1. Gangwei- Lunshui quartz monzonites granodiorites moderately enriched Sr, Rb but strongly Th. They have 0.706 3 Nd(t)≈－ 2. Shilu less Rb, Th LREE. more radiogenic (87Sr/86Sr)i = 0.708 4～ 9 6. It is concluded, terms geochemical features, that were generated from a metasomatism mantle source LILE while plutons derived followed extensive crystal fractionation. pluton was formed re- melting pre- existing underplating mafic rocks at lower crustal level. secular variation magma mostly attributed to upwelling asthenosphere extension overlying lithosphere Nanling Region during early Jurassic Cretaceous.