Genesis of Daba arcuate structural belt related to adjacent basement upheavals: Constraints from Fission-track and (U-Th)/He thermochronology

Abstract

Fission-track, (U-Th)/He thermochronology, and cooling properties indicate that the southern Daba arcuate zone (SDBAZ) underwent a distinctive phase of rapid cooling in 153-100 Ma at a rate of 1.44-1.90°C/Ma. This rapid uplifting strongly contrasts with (1) the previous, rapid foreland subsidence during Early to Middle Jurassic in response to late-orogenic compression from the Qinling belt, (2) the succeeding long, slow cooling phase and relative thermal stability that occurred during the 100-45 Ma period. This rapid cooling event in the SDBAZ parallels those experienced by two adjacent upheavals of Huangling (HLUZ) and Hannan-Micang (HMUZ), with cooling rates of 2.22-3.17°C/Ma for the HLUZ in 160-126 Ma, 4.91°C/Ma for the southern HMUZ in 150-125 Ma, as well as 2.11°C/Ma for the northern HMUZ in 150-105 Ma. Comparing thermal histories among the SDBAZ, the HLUZ, the HMUZ, and the Wudang metamorphic zone (WDMZ), we infer that the Daba arcuate structural belt formed in 153-100 Ma. The combined dating data support a correlation with a low-angle arcuate south-thrusting of the Qinling orogen triggered by northward convergence of the Yangtze Craton, contemporaneously encountering rigid basement obstructions from the HLUZ and the HMUZ, respectively. Both the SDBAZ and neighboring domains additionally underwent a comparatively fast cooling and uplift since about 45 Ma.

The geological and geodynamic condition on the formation of the Dabashan thrust nappe structure: Based on FLAC numerical modelling

“…After inter-continental collision orogeny (Late Triassic to Early Jurassic), Dabashan orocline continue reshaping during Late Jurassic to Early Cretaceous, proved by the sediment sequence and strata unconformity (Dong et al, 2005(Dong et al, , 2008Meng et al, 2005;Shi et al, 2007Shi et al, , 2012Li et al, 2007;Qu et al, 2009;Hu et al, 2012), isotopy dating (Cheng and Yang, 2009;Hu et al, 2009;Liu et al, 2011;Li et al, 2010Li et al, , 2012Li et al, , 2013, and apatite fission-track (Shen et al, 2009;Xu et al, 2010;Li et al, 2010, Shi et al, 2012Hu et al, 2012).…”

“…Regarding to the key factors that affect and control the formation of the Dabashan thrust nappe, there are mainly four opinions: 1) the uplift at both ends of the Bashan Arc fault is main mechanism (Jiang et al, 1982;Guo et al, 1996;Wang et al, 2003;Zhang et al, 2004;Dong et al, 2010;Xu et al, 2010;Shi et al, 2012); 2) tectonic extension at the margin of paleo-contiental and irregular boundary are the decisive factors , the dextral shear induced by the inconsistent morphology of the continental margins also plays a key role (He et al, 1997); 3) the arc-shaped fault that has been formed in the early stage of tectonic extension controls the thrust nappe developed toward southwest (Wang et al, , 2013; 4) the detachment layers under Dabashan unit is the main formation condition (Wang et al, , 2013.…”

Provenance and tectonic-paleogeographic evolution: Constraints from detrital zircon U–Pb ages of Late Triassic-Early Jurassic deposits in the northern Sichuan basin, central China

“…Recently, mylonites from the North Daba Shan belt yielded the Late Triassic-Early Jurassic 40 Ar/ 39 Ar plateau age of 222-189 Ma . These ages were interpreted as indicative of the first deformation phase that should be geodynamically related to the Qinling orogenesis (e.g., Shi et al, 2012;Xu et al, 2010). Compared with that in the Longmen Shan belt, the Triassic orogenesis on the north of Sichuan basin was less intensive, resulting in an unconspicuous wedge-shaped geometry in the N-S cross section ( Fig.…”

“…Recently, the Hannan-Micang Shan crystalline massifs were suggested to involve into the foreland growth of the Qinling belt at ca. 184-153 Ma (Xu et al, 2010). During the middle Lower to late Middle Jurassic time (188-165 Ma), rapid subsidence was proposed to occur in the Daba Shan foreland basin (Xu et al, 2010).…”

“…184-153 Ma (Xu et al, 2010). During the middle Lower to late Middle Jurassic time (188-165 Ma), rapid subsidence was proposed to occur in the Daba Shan foreland basin (Xu et al, 2010). The most prominent foredeep switched to the front of the northern Longmen Shan belt, which was accompanied by westward movement of the depocenter from the front of the Daba Shan belt.…”