U-Pb ages and Hf isotope composition of zircon from the Shimanto accretionary complex: Evidence for heterogeneous sources

Abstract

Copyright © 2020 by The Geochemical Society of Japan. The latter methods have proven to be powerful tools to identify the sources of the sediments (or sometimes only changing source areas) and the geologic make-up and evolution of source areas (e.g., Aoki et al., 2014; Bodet and Schärer, 2000; Deng et al., 2017; Hara et al., 2017; Lan et al., 2016). A well studied accretionary complex is the Shimanto Belt distributed along the Pacific side of south-west and central Japan along an active continental margin. This belt may have been displaced relative to the source area due to movements along the Median Tectonic Line (e.g., Ikeda et al., 2016; Sakashima et al., 2003). Numerous studies have dealt with various aspects of this belt. Age constraints were largely obtained by studies of the radiolarian biostratigraphy (e.g., Suzuki and Fukuda, 2012; Hara and Hara, 1919a, b). Recently, the dating of detrital zircon has been used to refine these age assignments (e.g., Hara and Hara, 2019b; Hara et al., 2017; Shibata et al., 2008; Tokiwa et al., 2016, 2017). Hara et al. (2017) also used the spectra of U-Pb zircon ages to discuss the provenance of the sediments that constitute the Shimanto belt in southern Shikoku. U-Pb ages and Hf isotope composition of zircon from the Shimanto accretionary complex: Evidence for heterogeneous sources