Magmatic consanguinity analysis of the Muchen intrusion and Xishantou Formation volcanic rocks in Zhejiang

Abstract：The Muchen intrusion and its adjacent Xishantou Formation volcanic rocks and subvolcanic rocks are intimately associated in space and their formation ages are close. Their rock types are all intermediate-acid and have a similar petrochemical composition, all belonging to a weakly alkaline rock series. The REE distribution patterns for various rock types are in the main consistent with the exception of Eu and so are the trace element distribution patterns. This indicates that they are products of evolution of consanguineous magma. They display similarities and consistency in respect to rock types, rock chemistry and REE and trace element geochemistry, and in addition, all their magmatic evolutions show a reverse sequence, which demonstrates that they are a consanguineous volcanic-intrusive rock association. Based on the Jurassic／Cretaceous boundary age of 145.5±4.0 Ma published by the International Commission on Stratigraphy in 2004, combined with the genetic relationship between the Muchen intrusion and its adjacent Xishantou Formation volcanic rocks, it seems more reasonable to define the age of the Muchen intrusion at Early Cretaceous.