⁴⁰ Ar/ ³⁹ Ar Thermochronology on Central China Orogen: Cooling, uplift and implications for orogeny dynamics

Abstract

40 Ar/ 39 Ar geochronology was carried out on the non-deformed synorogenic granitoid plutons from the Qinling-Dabie Orogen. The new model cooling history (MCH) method is applied to K-feldspar to obtain information about its cooling history. MCH is a quicker and easier method of calculating cooling histories compared with the multi-domain diffusion (MDD) model. Cooling histories indicate that Qinling-Dabie suffered differential uplift and denudation processes since the collision in the Late Triassic. East Qinling uplifted and denuded rapidly from c. 181-187 to c. 150 Ma at a rate of c. 20 8C Ma 21 , three times as fast as west Qinling which was exhumed at a rate of c. 6.6 8C Ma 21 from c. 195-190 to c. 100 Ma. Although west and east Qinling started uplift and denudation at the same time, east Qinling reached the 150 8C geothermal line (c. 7.5 km deep) at c. 150 Ma, earlier than west Qinling by c. 50 myr, suggesting that earliest collision and strongest compression occurred in east Qinling. Dabie is characterized with a polyphased process of uplift and denudation, implying that the subduction of south China block in this region was multi-staged. The emplacement of the granitoids and uplift pattern along Qinling-Dabie may be due to delamination of the root of the mountains or the slab break-off. Cooling histories suggest that more mass had been removed from the root of east Qinling than west Qinling and Dabie; the final delamination occurred in Dabie at c. 100 Ma but affected the whole Qinling-Dabie orogen.

40Ar/39Ar geochronology of the North China and Yangtze Cratons: New constraints on Mesozoic cooling and cratonic destruction under East Asia

“…Sample 091128–1 presents a very distinct age spectrum pattern and a much younger maximum age (131.0 Ma) than the other five, suggesting that it has experienced a distinct cooling history. Its biotite age is similar to those of the postcollisional undeformed granites in the Dabie ultrahigh metamorphic belt (Zircon U‐Pb and biotite 40 Ar/ 39 Ar ages of 110–130 Ma) [ Zhao et al ., ; Wang et al ., ]. The pattern of the K‐feldspar age spectrum (Figure f) is also similar to those observed on the Dabie granites [ Wang et al ., ].…”

“…Its biotite age is similar to those of the postcollisional undeformed granites in the Dabie ultrahigh metamorphic belt (Zircon U‐Pb and biotite 40 Ar/ 39 Ar ages of 110–130 Ma) [ Zhao et al ., ; Wang et al ., ]. The pattern of the K‐feldspar age spectrum (Figure f) is also similar to those observed on the Dabie granites [ Wang et al ., ]. In addition, the nearby location (Figure ) also emphasizes a close relationship of the magmatic genesis between 091128–1 and those undeformed granites of the Late Mesozoic in Dabie.…”

Quantifying Crustal Thickness in Continental Collisional Belts: Global Perspective and a Geologic Application

“…This requires a mechanism to thin the crust over a relatively short time period. Previous field and geochemical studies suggested that the SQB experienced rapid uplift and exhumation since ~210 Ma 30 , 48 , 49 . Magmatic activity decreased significantly after ~208 Ma as well and was dominated by volumetrically small and felsic plutonism indicating that mafic magmatic additions have contributed little to magma generation and crustal thickness (Fig.…”

Late Mesozoic Exhumation of the Huangling Massif: Constraints on the Evolution of the Middle Yangtze River

“…More low-temperature thermochronology results show that Daba Shan (Fig. 10a) (110 Ma;Tian et al, 2012;Li W et al, 2017), Qinling-Dabie Shan (110 Ma;Grimmer et al, 2002;Hu et al, 2006b;Heberer et al, 2014;Wang et al, 2015;Wang M et al, 2022), Mufu Shan (120 Ma;Lin et al, 2000;Ji et al, 2018;Shen et al, 2020), and Xuefeng Shan (100 Ma;Chu et al, 2020), as well as the eastern Sichuan Basin (100 Ma;Shi et al, 2016), experienced rapid exhumation again in the late Early Cretaceous. Therefore, the exhumation of the Huangling Massif was spatially synchronized with the aforementioned orogenic belts.…”