Sichuan Basin and beyond: Eastward foreland growth of the Tibetan Plateau from an integration of Late Cretaceous‐Cenozoic fission track and (U‐Th)/He ages of the eastern Tibetan Plateau, Qinling, and Daba Shan

Abstract

Combining 121 new fission track and (U‐Th)/He ages with published thermochronologic data, we investigate the Late Cretaceous‐Cenozoic exhumation/cooling history of the eastern Tibetan Plateau, Qinling, Daba Shan, and Sichuan Basin of east central China. The Qinling orogen shows terminal southwestward foreland growth in the northern Daba Shan thrust belt at 100–90 Ma and in the southern Daba Shan fold belt at 85–70 Ma. The eastern margin of Tibetan Plateau experienced major exhumation phases at 70–40 Ma (exhumation rate 0.05–0.08 mm/yr), 25–15 Ma (≤1 mm/yr in the Pengguan Massif; ~0.2 mm/yr in the imbricated western Sichuan Basin), and since ~11–10 Ma along the Longmen Shan (~0.80 mm/yr) and the interior of the eastern Tibetan Plateau (Dadu River gorge, Min Shan; ~0.50 mm/yr). The Sichuan Basin records two basin‐wide denudation phases, likely a result of the reorganization of the upper Yangtze River drainage system. The first phase commenced at ~45 Ma and probably ended before the Miocene; >1 km of rocks were eroded from the central and eastern Sichuan Basin. The second phase commenced at ~12 Ma and denudated the central Sichuan Basin, Longmen Shan, and southern Daba Shan; more than 2 km of rocks were eroded after the lower Yangtze River had cut through the Three Gorges and captured the Sichuan Basin drainage. In contrast to the East Qinling, which was weakly effected by late Cenozoic exhumation, the West Qinling and Daba Shan have experienced rapid exhumation/cooling since ~15–13 Ma, a result of growth of the Tibetan Plateau beyond the Sichuan Basin.

Flyover Crustal Structures Beneath the Qinling Orogenic Belt and Its Tectonic Implications

“…The HVZ beneath the SNHL dome is flat and shallow, while the HVZ beneath the HNMC dome is compact and deep (Figures a, d, and f). The velocity variances between the HNMC dome and the Dabashan Mountains are much greater than those between the WQL and the HNMC dome (Figure a); these differences were probably caused by compressional forces originating from the eastward growth of the TP during the Late Cenozoic (circa 15 Ma; Tian et al, ; Yang et al, ). The LVZ beneath the Sichuan Basin sharply changes into an HVZ beneath the HNMC dome and QOB (Figures d and e); this LVZ is related to the compressional environment that generated a series of foreland fold‐thrust belts in northeastern Sichuan Basin from the late Middle Jurassic (circa 165 Ma) to the early Late Cretaceous (circa 95 Ma; Dong et al, ; Yang et al, ).…”

Thermochronological Constraints on the Late Cenozoic Morphotectonic Evolution of the Min Shan, the Eastern Margin of the Tibetan Plateau

“…AHe, apatite fission track (AFT), and ZHe age‐elevation plots for samples located between the Huya and Minjiang faults (a, c) and east of the Huya fault (b). In panels a and c, new AHe data from the top two samples, two AHe and ZHe ages from Kirby et al (; reference 1), and two AFT ages from Yang et al (; reference 2) are plotted for comparison. Inserted plots in panels a and c are close‐up views for areas marked by dashed rectangles.…”

“…Thermal history modeling, combining these age results with K‐feldspar Ar‐Ar releasing spectrum, indicates a late Mesozoic‐middle Cenozoic phase of slow cooling, followed by enhanced cooling starting at ~5 Ma. The data set reported in Yang et al () includes two AFT ages of 11.4 ± 0.9 Ma and 30.4 ± 2.1 Ma from the Minjiang fault zone (Figure ).…”

“…Thermochronological ages of the samples are compiled in rectangles (see legend for explanation). Numbered previous studies are (1) Arne et al (), (2) Kirby et al (), and (3) Yang et al (). The dashed line marks the possible northern continuation of the Huya fault.…”

Oligocene‐Early Miocene Topographic Relief Generation of Southeastern Tibet Triggered by Thrusting

“…AFT PAZ = apatite fission track partial annealing zone; ASRR = Ailao Shan‐Red River shear zone; CD = Chuandian block; CHT = Chenghai thrust; CSSZ = Chongshan shear zone; JQTB = Jinhe‐Qinghe thrust belt; RRF = Red River fault; YTB = Yulong thrust belt. White stars denote accelerated exhumation phases constrained by thermochronology in southeastern Tibet, with black numbers indicating the duration: 0 = This study, 1 = E. Wang, Kirby, et al (), 2 = Tian et al (), 3 = Clark, House, et al () and Ouimet et al (), 4 = Godard et al (), 5 = Xu and Kamp (), 6 = Zhang et al (), 7 = S. Wang, Jiang, et al (), 8 = Tian et al (), 9 = Zhang et al (), 10 = Lacassin et al (), 11 = Yang et al (), and 12 = Wilson and Fowler (). Blue numbers indicate paleoaltimetry estimates: 13 = Hoke et al (), 14 = Li et al (), 15 = Gourbet et al (), 16 = Tang et al ().…”