Meso‐Cenozoic Tectonic Events Recorded by Apatite Fission Track in the Northern Longmen‐Micang Mountains Region

Abstract

Abstract:There is a cross‐cutting relationship between the E‐W trending structures and the NE‐trending structures in the northern Longmen‐Micang Mountains region, which reflects possible regional tectonic transition and migration. Apatite fission track (AFT) analyses of 15 samples collected from this area yield apparent ages varying from 30.3±4.2 Ma to 111.7±9.0 Ma and confined‐track‐lengths ranging from 10.6±0.3 μm to 12.4±0.1 μm. Four specific groups were identified on the basis of the Track Age Spectrum Calculation (TASC) patterns, i.e., 143–112 Ma, 93.6–88 Ma, 42–40 Ma and ∼25.6 Ma. These age groups correspond to the spatial distributions of datasets and may represent four tectonic events. Together with the regional deformation patterns, the four age groups are interpreted to indicate tectonic superposition, transition and migration during the Meso‐Cenozoic with the following possible order: (1) the Micang Mountains belt was dominated by the E‐W trending structure during 143–112 Ma; (2) the contraction of the Longmen Mountains belt from the NW to the SE during 93.6–88 Ma led to the superposition of the NE‐trending structures over the E‐W trendinding structures; (3) dextral strike‐slip shear dominated the Longmen Mountains belt at 42–40 Ma; (4) westward migration of the active tectonic belt occurred from 93.6–25.6 Ma in a break‐back sequence in the northern Longmen Mountains belt. The Late Cenozoic tectonics in the northern Longmen Mountains belt are characterized by the dextral strike‐slip shear and the occurrence of westward break‐back sequence of deformations. As a result, north‐south differences in deformations along the Longmen Mountains belt were intensified since the Miocene time and strains were mainly accumulated in the hinterland of the Longmen Mountains instead of being propagated to the foreland basin.

New Apatite Fission‐Track Ages of the Western Kuqa Depression: Implications for the Mesozoic–Cenozoic Tectonic Evolution of South Tianshan, Xinjiang

“…Low-temperature thermochronology is a powerful method to elucidate the timing and magnitude of exhumation in response to uplift, deformation, and erosion (Stockli et al, 2000;Ehlers et al, 2003;Zhu et al, 2008;Gavillot et al, 2010;Lei et al, 2012;Wilke et al, 2012;Song et al, 2013;Yu et al, 2014;Ren et al, 2015), especially apatite fission-track analysis and apatite (U-Th)/He (AHe) dating. In this work, we present new apatite fission-track ages obtained from a continuous Lower Triassic to Quaternary sedimentary series in the western Kuqa Depression.…”

New Detrital Apatite Fission Track Thermochronological Constraints on the Meso-Cenozoic Tectono-Thermal Evolution of the Micangshan-Dabashan Tectonic Belt, Central China

“…As one of the most important thermochronological methods, apatite fission track (AFT) parameters provide quantitative information on cooling and record the thermal history of rocks (Green et al, 1986;Green, 1988;Gallagher, 2003), and these parameters are typically interpreted as a result of surface uplift and erosion (Tian et al, 2010;Tian et al, 2012;Tian et al, 2013;Lei et al, 2012;Ren et al, 2015;Qi et al, 2016;Powell et al, 2017;. Previous work that has focused on the thermal history derived from a variety of thermochronometry dating methods, such as U-Pb, 40 Ar/ 39 Ar, (U-Th)/He and AFT, in the Longmenshan, Micangshan and Dabashan areas has been published, and the dating methods and results have mainly been applied to investigate the cooling events and the coupling process of the Tibetan Plateau uplift (Arne et al, 1997;Enkelmann et al, 2006;Shen et al, 2007;Richardson et al, 2008;Li ZW et al, 2010;Li ZW et al, 2012;Li JH et al, 2010;Li et al, 2011;Chang et al, 2010;Tian et al, 2010;Tian et al, 2012;Tian et al, 2013;Tian et al, 2016;Tian YT et al, 2018;Yang et al, 2013;Yang et al, 2017;Shen et al, 2019).…”