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

Abstract

Lithospheric destruction of the North China Craton (NCC) is a prominent phenomenon during the Mesozoic, but the timing and process are still in dispute. Furthermore, whether the Yangtze Craton (YTC) was also destructed is controversial. Twenty samples collected from the NCC and YTC were subjected to high-resolution 40 Ar/ 39Ar geochronological and thermochronological studies. Average cooling rates of 450-150°C were estimated, showing that a rapid cooling event (~12°C/Ma) occurred on the NCC but not on the YTC during the Late Mesozoic. Crustal thickness can be roughly estimated by using pure conductive cooling showing that the crust of the NCC in the Jurassic was thicker than in the Cretaceous. Nonlinear cooling histories and cooling rates obtained by using multidomain diffusion theory show that the upper crusts of NCC and YTC had different cooling patterns during the Mesozoic. Combined with the sedimentation rates on the NCC, we argue that lithospheric thinning of the NCC began in the northern portion at~140-135 Ma and peaked in the central and eastern portions at~125-100 Ma, at a cooling rate of~9.6°C/Ma. In contrast, the YTC cooled gently during 200-75 Ma at a rate of 1.2°C/Ma, implying that the lithospheric thinning did not happen there during this time. Pure conductive cooling suggests that the crust of the YTC in the Late Triassic was thicker than the NCC in the Cretaceous; therefore, we argue that the lithospheric destruction in the YTC might have occurred after~75 Ma.

Differential growth of the northern Tibetan margin: evidence for oblique stepwise rise of the Tibetan Plateau

“…Although less than 20% of the total released 39 Ar resides within these low-temperature domains (Fig. 3), the behavior30313233 of multi-diffusion domains within K-feldspar suggests that these staircase spectra are the result of slow cooling and, therefore, record cooling ages between ~350–150 °C. Their minimum ages of 198.8 ± 2.4 and 90.3 ± 2.1 Ma (Fig.…”

“…Characterized by complicated microstructures that serves as domains with different sizes, argon retention properties and closure temperatures303146, K-feldspars are potentially able to record 40 Ar/ 39 Ar ages of closure temperatures ranging from 350 down to 150 °C as they cool2747, and thermal histories can consequently be extracted3031323348. A high resolution (36–40 steps) step-heating technique was applied from 450 to 1300 °C in a 40 Ar/ 39 Ar analysis to reveal the argon distributions within the K-feldspar grains in as much detail as possible (Table S3).…”

Cretaceous Episodic Extension in the South China Block, East Asia: Evidence From the Yuechengling Massif of Central South China

“…However, the process and temporal‐spatial distribution of the extension, and its geodynamic mechanisms, still require refinement with further structural, geochronological, and petrological work. In comparison with the NCB in which most of the extensional domes or MCCs appeared in the Early Cretaceous (Lin et al, ; Wang et al, ; Wang, Zheng, et al, ), the SCB presents a protracted extensional regime manifested by extensional domes and basins active from 140 to 80 Ma, but each of these domes seems to have a distinctive evolution history (Li et al, , ; Lin et al, ; Shu et al, ; Zhou & Li, ; Zhu, Xie, et al, ).…”

Cretaceous exhumation of the Triassic intracontinental Xuefengshan Belt: Delayed unroofing of an orogenic plateau across the South China Block?

“…1). The amalgamation of the two blocks occurred in the Neoproterozoic, and gave rise to subduction-collision-related rock formations, including arc-related magmatic and sedimentary rocks between 1.0 and 0.9 Ga (Li, 1999;Li et al, 2009;Wang et al, J o u r n a l P r e -p r o o f 2013, 2016), metamorphic units (1.1-0.9 Ga) (Li et al, 2002, and post-orogenic intrusions (0.83-0.8 Ga) (Wang et al, 2006;Zheng et al, 2008).…”