Abstract
The relationship between the tectonic event of the Linqing Sub-basin and the destruction of the North China Craton (NCC) is an important factor to consider when studying geodynamic mechanisms in eastern China. In the current study, we present a low-temperature apatite thermochronological analysis of 14 samples to study the tectonic event of the Linqing Sub-basin. Our data showed that the apatite fission track (AFT) ages were in the range of 53.5–124.4 Ma, and the average track lengths were 8.00–11.24 μm. The grain ages showed that 10 samples had mixed ages and were characterized by discordant distribution. The minimum ages decomposed from AFT ages mainly ranged from 105.3 to 40.8 Ma. We identified a break-in-slope from the depth-minimum age profile, which was related to the Meso-Cenozoic tectonic event. The AFT age data could be decomposed into three age groups, namely, P3 (394.8–215.7 Ma), P2 (124.6–83.4 Ma), and P1 (70.7–40.8 Ma), indicating three significant tectonic events in the NCC. P3 is related to the uplift of the NCC at 445.0–315.0 Ma and deformation and magmatism at 320.0–200.0 Ma. P2 corresponds to the Mesozoic tectonic activities, such as the closure of the Mongol–Okhotsk Ocean, the turning of the Izanagi plate and mantle convection. P1 mainly corresponds to the Izanagi–Pacific ridge, the closure of the Tethys Ocean, and the rotation of the Philippine Sea plate in the Cenozoic. Our study provides evidence for the destruction of the NCC, and has significance for the understanding of the deep mechanism.
Highlights
This paper provides a geothermal basis that can be used to further our understanding of the tectonic evolution in the Bohai Bay Basin (BBB)
apatite fission track (AFT) ages range from 124.4 ± 24.9 to 53.5 ± 5.4 Ma, with mean track lengths ranging from 8.00 ± 2.51 to 11.24 ± 1.27 μm
All samples are designated as reset (R), mixed reset (MR), partially reset (PR), and unreset (D) (Table 2, Tables S2 and S3)
Summary
Evidence from geophysics [2,3,4] and geochemistry [5,6,7] suggests that the lithosphere of the eastern NCC was thinned by over 100 km during the Meso-Cenozoic. The Linqing Sub-basin of the Bohai Bay Basin (BBB), located in the center of lithosphere thinning in the eastern NCC (Figure 1), experienced mantle transformation, magmatic activity and basin evolution during multiple stages of tectonothermal events [8,9,10]. Due to the deep burial of Cenozoic strata in the BBB, where burial depths are as great as 10,000 m [15], AFT samples in most areas have undergone partial annealing or even complete reset under the influence of temperature. Data that do not pass the χ2 test a statistical deconvolution of sample grain age distributions cannot be used to reconstruct the thermal history [16,17]
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