Cretaceous volcanic-plutonic magmatism in SE China and a genetic model

Intensive and extensive Cretaceous volcanic-plutonic magmatism occurred in the coastal area of SE China, which is an important part of circle Pacific continental margin associated with copper and gold metallogenesis. Repre-sentative calderas are studied in detail, which show coeval, cogenetic and complementary geochemical and petrological signatures for the eruptive and intrusive units. Contemporary abyssal plutonic associations of gabbro-diorite-granite are revisited for their micropetrographical and geochemical fingerprints, which show dis-tinct compaction-driven fractionation of plagioclase and amphibole for the gabbroic rocks. Microtextures and trace elements are also analyzed for underplating/intraplating gabbroic rocks in the lower crust, which were car-ried out by Cenozoic basalt as deep-seated xenoliths, to test accumulation and fractionation of the mantle-derived magma. A dataset of geochemistry for the Cretaceous volcanic-plutonic rocks is compiled from previous and this studies. Comparisons with magmatism of typical extensional continental arc (northern Cascades in North America), compressional continental arc (Andes in South America) and rifted arc (Taupo in New Zealand) show that the Cretaceous magmatism in the coastal area of SE China is more approximate to the rifted arc one and dominated by felsic magmatism. A series of numerical modeling using major and trace elements and isotopes, as well as petrographic evidence reveal that a combination of fractional crystallization of mantle-derived magma, partial melting of pre-existed mid-lower crust and magma mixing played an important role in the compositional variations of the Cretaceous volcanic-plutonic rocks in SE China. By integrating petrology, geochemistry and geophysical data, we propose a trans-crustal magma system model for the Cretaceous volcanic-plutonic magmatism in SE China. In this model, significant fractionation combining distinct contribution of crustal materials can interpret the dominant felsic component feature. Therefore, the Cre-taceous volcanic-plutonic rocks in SE China recorded the evolution of a continental arc built on a complex trans-crustal magmatic system. (c) 2020 Elsevier B.V. All rights reserved.

Automated summary

Intensive and extensive Cretaceous volcanic-plutonic magmatism occurred in the coastal area of SE China, with a dominant felsic magmatism more approximate to the rifted arc. Fractional crystallization of mantle-derived magma, partial melting of pre-existed mid-lower crust, and magma mixing played important roles in the compositional variations of the rocks. The evolution of a continental arc built on a complex trans-crustal magmatic system is recorded in the Cretaceous volcanic-plutonic rocks in SE China.