Skip to main content

Research Repository

Advanced Search

Petrogenesis of Cretaceous (133–84 Ma) intermediate dykes and host granites in southeastern China: Implications for lithospheric extension, continental crustal growth, and geodynamics of Palaeo-Pacific subduction

Yang, Jinbao; Zhao, Zhidan; Hou, Qingye; Niu, Yaoling; Mo, Xuanxue; Sheng, Dan; Wang, Lili

Petrogenesis of Cretaceous (133–84 Ma) intermediate dykes and host granites in southeastern China: Implications for lithospheric extension, continental crustal growth, and geodynamics of Palaeo-Pacific subduction Thumbnail


Authors

Jinbao Yang

Zhidan Zhao

Qingye Hou

Yaoling Niu

Xuanxue Mo

Dan Sheng

Lili Wang



Abstract

This paper presents U-Pb zircon geochronology, petrology, and major and trace element, Sr-Nd and zircon Hf isotopic geochemistry of Cretaceous granites and intermediate dykes in the Quanzhou and Xiamen regions of southeastern China. These data are used to investigate igneous petrogenesis and Cretaceous tectonic evolution, and interpret the geodynamics of Palaeo-Pacific slab subduction. Granites in Quanzhou and Xiamen range in age from 133 Ma to 87 Ma, have high SiO2 and K2O contents, low abundances in P2O5, and an A/CNK index that ranges from 0.97 to 1.09, indicating that they are high-K calc-alkaline metaluminous I-type rocks. Slightly negative ɛ Nd (t) values (− 1.2 to − 4.4), young Nd model ages (0.87 Ga to 1.20 Ga) and positive ɛ Hf (t) values (− 0.5 to + 9.9) of zircon grains indicate that the granites were derived from magmas that melted amphibolite in the middle-lower crust, and which may have assimilated country rocks during emplacement in shallow chambers. The intermediate dykes have no genetic link to the granites and magma mixing was negligible. Eight dyke samples have low SiO2 and high MgO, Ni and Cr contents. Negative ε Nd (t) values (− 1.5 to − 2.7) and positive ε Hf (t) values (2.7 to 7.6) suggest that the dykes were derived from residual basic lower crust after mafic-crystal accumulation. Two samples of adakite-like dykes are characterised by high Sr/Y ratios (89 to 100) and high SiO2low K2O, Ni, Cr contents. In combination with slightly negative ε Nd (t) values (− 1.7 to − 1.8) and positive ε Hf (t) values (2.9 to 4.3), the adakite-like dykes were derived from cumulate basic lower crust which had a mixed source between depleted mantle- and crust-derived melts. Based on our data, combined with previously published work, we suggest that extension-induced middle-lower crustal melting and underplating of mantle-derived basaltic melts were the principal driving mechanisms for Cretaceous granitic magmatism in coastal Fujian Province. Extension was related to subduction retreat whereas steep slab subduction caused underplating of mantle-derived basaltic melts. These processes were coupled and mainly responsible for the tectonic transition during the Cretaceous from compression to extension in the coastal belt of the Cathaysia Plate.

Citation

Yang, J., Zhao, Z., Hou, Q., Niu, Y., Mo, X., Sheng, D., & Wang, L. (2018). Petrogenesis of Cretaceous (133–84 Ma) intermediate dykes and host granites in southeastern China: Implications for lithospheric extension, continental crustal growth, and geodynamics of Palaeo-Pacific subduction. Lithos, 296-299, 195-211. https://doi.org/10.1016/j.lithos.2017.10.022

Journal Article Type Article
Acceptance Date Oct 29, 2017
Online Publication Date Nov 4, 2017
Publication Date Jan 1, 2018
Deposit Date Nov 7, 2017
Publicly Available Date Mar 29, 2024
Journal Lithos
Print ISSN 0024-4937
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 296-299
Pages 195-211
DOI https://doi.org/10.1016/j.lithos.2017.10.022

Files





You might also like



Downloadable Citations