Role of deep-Earth water cycling in the growth and evolution of continental crust: Constraints from Cretaceous magmatism in southeast China
MetadataShow full item record
Funding and Sponsorship
The late Mesozoic igneous province in southeast China provides an excellent opportunity to understand the processes that controlled the growth and evolution of Phanerozoic continental crust. Here we report petrological, whole-rock geochemical and isotopic data, and in situ zircon U–Pb–Lu–Hf isotopic data from granitoids and associated gabbros in the Pingtan and Tong'an complexes, southeast China. Through combining the new results with published datasets in southeast China, we show that the Early Cretaceous magmatic rocks are dominated by juvenile Nd–Hf isotopic compositions, whereas the Late Cretaceous ones display less radiogenic Nd–Hf isotope signatures. Furthermore, Nd–Hf isotope systematics are coupled with decreasing abundance of hydrous minerals and an increase of zircon saturation temperatures. Compiled zircon Hf–O data indicates that the 117–116 Ma granites have zircon δ18O values ranging from mantle values (close to 5.3‰) to as low as 3.9‰, but with dominantly positive initial epsilon Hf (εHf(t)) values. Zircon grains from 105 to 98 Ma rocks have δ18O values plotting within the mantle-like range (6.5‰ − 4.5‰), but mainly with negative εHf(t) values. Zircon grains from ca. 87 Ma rocks have positive εHf(t) values (+ 9.8 to + 0.7) and a large range of δ18O values (6.3‰ − 3.5‰). The variations in Hf–Nd–O isotopic compositions are correlated with decreasing abundance of magma water contents, presenting a case that water-fluxed melting generated large-scale granitic magmatism. Deep-Earth water cycling provides an alternative or additional mechanism to supply volatiles (e.g., H2O) for hydrous basaltic underplating, continental crustal melting, and magmatic differentiation.
Showing items related by title, author, creator and subject.
Integrated in situ U–Pb age and Hf–O analyses of zircon from Suixian Group in northern Yangtze: New insights into the Neoproterozoic low-δ18O magmas in the South China BlockYang, Y.; Wang, Xuan-Ce; Li, Q.; Li, X. (2016)The mid- to late-Neoproterozoic magmatic rocks from the northern margin of the Yangtze Block are major protoliths of high-pressure (HP) and ultrahigh-pressure (UHP) metamorphic rocks in the Dabie–Sulu orogenic belt along ...
Nonglacial origin for low-δ18O Neoproterozoic magmas in the South China Block: Evidence from new in-situ oxygen isotope analyses using SIMSWang, Xuan-Ce; Li, Zheng-Xiang; Li, X.; Li, Q.; Tang, G.; Zhang, Q.; Liu, Y. (2011)Low-δ18O signatures in supracrustal rocks have been used as geochemical proxies for cold paleoclimates, e.g., glaciations. Unusual low-δ18O values found in Neoproterozoic igneous rocks in parts of the South China Block ...
Sources and conditions for the formation of Jurassic post-orogenic high-K granites in the Western Guangdong Province, SE ChinaHuang, Hui-Qing (2012)High-K granites have become volumetrically important since at least Proterozoic. Their study bears important implications to crustal and tectonic evolutions. Despite of intensive research, sources and conditions for the ...