Decoupling between Nd-Hf isotopic evolution of Permian to Triassic granitoids and crustal thickness variation in the westernmost Mongol-Okhotsk Orogen
Year: 2025
Type: article
Abstract: Nd-Hf isotope evolution in arc magmas has been widely used to trace the advance and retreat of subduction zones over time. However, the reliability of this method has been questioned. One way to assess its validity is by comparing it with LaN/YbN or Sr/Yb ratios, which are well-established proxies for crustal thickness. In this study, we present new Nd-Hf isotopic data from the Permian to Triassic Hangay Batholith in the western Mongol-Okhotsk Orogen (Hangay Mountains), to evaluate the role of Nd-Hf isotopes in tracing crustal thickness variations along convergent plate boundaries. Our results show that granitoids from the Hangay Batholith likely originated from partial melting of crustal materials, with a possible mantle contribution. These granitoids have moderate εNd(t) and εHf(t) values, with no significant shift from Permian to Triassic, which contrasts with the continuous crustal thickening indicated by LaN/YbN ratios. This inconsistency between Nd-Hf isotope evolution and crustal thickness variation is likely due to the heterogeneous crustal architecture in this accretionary orogen. Our findings highlight the need for caution when linking Hf and Nd isotope evolution with extensional and contractional tectonics.
Source: Geological Magazine
Authors: Jiaqi Ling, Pengfei Li, Chao Yuan, Narantsetseg Tserendash
Language: English
Subfield: Geophysics
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,550
OpenAlex ID: W4411284402