Research Article Rapid Eocene Exhumation of the West Qinling Belt: Implications for the Growth of the Northeastern Tibetan Plateau

GeoScienceWorld Lithosphere Volume 2020, Article ID 8294751, 12 pages https://doi.org/10.2113/2020/8294751

1,2,3 1,2 1,2 1,2 Yi-Peng Zhang , Wen-Jun Zheng , Wei-Tao Wang , Yun-Tao Tian , 3 1,2 4 1,2 1,2 Renjie Zhou , Bin-Bin Xu, Min-Juan Li, Yong-Gang Yan, Qing-Ying Tian, 1,2 and Pei-Zhen Zhang

1Guangdong Provincial Key Laboratory of Geodynamics and Geohazards, School of Earth Sciences and Engineering, Sun Yat- Sen University, Guangzhou, 510275, China 2Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai 519082, China 3School of Earth and Environmental Sciences, The University of Queensland, St. Lucia, QLD 4072, Australia 4Gansu Earthquake Agency, Lanzhou 730000, China

Correspondence should be addressed to Wen-Jun Zheng; [email protected]

Received 5 March 2020; Accepted 7 September 2020; Published 6 November 2020

Academic Editor: Andrea Billi

Cenozoic exhumation in the northeastern Tibetan Plateau provides insights into spatial-temporal patterns of crustal shortening, erosion, landscape evolution, and geodynamic drivers in the broad India-Eurasia collision system. The NW-SE trending West Qinling Belt has been a central debate as to when crustal shortening took place. Within the West Qinling Belt, a thick succession of Cretaceous sedimentary rocks has been deformed and exhumed along major basin-bounding thrust faults. We present new apatite (U-Th)/He ages from the hanging wall and footwall of this major thrust. Contrasting thermal histories show that rapid cooling commenced as early as ca. 45 Ma and continued for 15–20 Myr for the hanging wall, whereas the footwall experiences continuous cooling and slow exhumation since the late Mesozoic. We infer that accelerated exhumation was driven by thrusting in response to the northward growth of the Tibetan Plateau during the Eocene (ca. 45–35 Ma) based on regional sedimentological, structural, and thermochronological data.

1. Introduction tion of the Asian lithospheric mantle may have resulted in the growth and progressive development of the Tibetan Plateau Ongoing collision between India and Eurasia has exerted a toward the northeast from active plate boundaries [2]. The profound inﬂuence on landscape development, fault activa- onset of ﬂexural basins (e.g., Linxia Basin) and provenance tion, and seismicity in East Asia [1–3]. Continuing continental change in the Lanzhou Basin imply pulsed crust shortening convergence may have reactivated pre-Cenozoic orogenic and the growth of the WQB during the late Oligocene [11, belts (e.g., Tian Shan-Altaids, Qilian Shan, and Qinling Belt) 12]. Second, simultaneous contractional deformation in the where preexisting faults of crustal scales exist [2, 4–8]. Studies northeastern plateau margin may have taken place in the have suggested that basin formation, mountain uplift, fault early Cenozoic, accompanying the initial development of activity, and plateau growth may have protracted throughout the Tibetan Plateau, implying a relatively constant bulk strain the Cenozoic Indo-Asian collision, but details regarding crust rate of the Asian lithosphere around the same time [8, 13]. shortening histories are still enigmatic [2, 4–10]. Low-temperature thermochronologic data from hanging wall There are three schools of thoughts regarding the timing blocks of major thrust systems [14, 15], depositional history of deformation along the West Qinling Belt (WQB) in the of major sedimentary basins [16–18], and vertical axis rota- northeastern Tibetan Plateau. First, oblique stepwise subduc- tion of subblock/basins [19] indicate that the onset of moun-

Downloaded from http://pubs.geoscienceworld.org/gsa/lithosphere/article-pdf/doi/10.2113/2020/8294751/5293396/8294751.pdf by guest on 30 September 2021 2 Lithosphere

tain building took place along the northeastern plateau mar- middle Triassic clastic rocks are found along the LTF and gin associated with the initial growth of the Tibetan Plateau. Guanggai Shan-Die Shan Fault (GDF). Rocks along the Third, the presence of unconformities between lower Creta- Diebu-Wudu Fault (DWF) include Silurian sandstones and ceous and Tertiary units along the WQB could be related to siltstones, as well as minor Devonian and Carboniferous mountain building and significant uplift during the late Cre- sandstones. The Kangxian-Wenxian-Maqu Fault (KMF) is taceous, which may have no connection with the Cenozoic a secondary fault of the SDSZ and reactivated by Mesozoic growth of the Tibetan Plateau [20, 21]. and Cenozoic intracontinental orogenesis. Whether significant contractional deformation took In the WQB, a regional angular unconformity separates place in the WQB between late Cretaceous and Paleogene lower Cretaceous sediments of the Donghe Group from and whether such events were widespread of WQB remain underlying pre-Jurassic strata (Figures 1(a) and 2(a)). Upper critically unknown. When the Tibetan Plateau grew north- Cretaceous strata are absent. Lower Cretaceous rocks consist ward to the northeastern region remains enigmatic. For clear primarily of purple-red alluvial-fluvial-lacustrine deposits, answers to this question, we used low-temperature thermo- dominated by conglomerate, sandstone, and mudstone, with chronology to examine the exhumation history and possible intercalations of coal measures in the lower part. Paleogene topographic evolution of the WQB by constraining the cool- strata (Guyuan Group), which are separated from the pre- ing of the hanging wall and footwall of a major thrust fault. Cenozoic rocks by an angular unconformity, crop out Our new data, in combination with previously published geo- sparsely within intermontane basins in the WQB [21, 34]. logical data, are analyzed to advance the understanding of The Guyuan Group is dominated by terrestrial red beds orogenic processes in the northeastern Tibetan Plateau. and massive matrix-supported conglomerate. Oligocene ver- tebrate fossils (the Longjiagou fauna) have been reported 2. Geological Setting from the Guyuan Group [21, 34–36]. The Huicheng Basin (HCB in Figure 1) is a northeast- The Qinling Orogen, which trends E-W in central China, was trending intermountain basin in the southeastern WQB, formed during the middle-late Triassic collision between the bounded by the KMF to the south and the Chenxian Fault North China Block and the South China Block [20, 22, 23]. (CXF) to the north. The Huicheng Basin consists of lower The Qinling Belt is divided into the West Qinling Belt Cretaceous rocks (Donghe Group), whose ages are deter- (WQB) and the East Qinling Belt, separated by the Foping mined by spore-pollen assemblages [37, 38]. Rocks are dom- Dome (Figure 1(a)) [23]. The WQB may have experienced inated by purplish-red conglomerate, gray pebbly sandstone, at least two major episodes of shortening during Mesozoic grayish-green mudstone layers with shale interbeds, and coal – time [4, 20, 24 27]. The early episode has been attributed seams. The succession is divided into the Tianjiaba (K1t), to the collision between the North China Block and the South Zhoujiawan (K1z), and Huaya (K1h) Formations, whose ages China Block in the Mesozoic [22, 23, 28, 29], and the later were determined by fossil assemblages, lithofacies associa- stage is thought to be related to the northward growth of tions, and depositional contacts. The lowermost K1t consists the Tibetan Plateau during the Cenozoic [2, 4, 12, 14, 16, of purplish-red massive conglomerate facies and well-sorted, 30]. Deep seismic reflection shows that the active deforma- coarse- to fine-grained glutenites, which have been inter- tion is dominated by upper crustal shortening, middle crustal preted to represent a transition from alluvial fan to sandy shearing, and mantle-derived magmatism since the Oligo- braided river lithofacies. The overlying K1z includes delta cene (Figure 1(b)) [24, 31, 32]. fan lithofacies, consisting of coarse sandstone interbedded The WQB is bounded by the West Qinling Fault (WQLF) with thin siltstone and mudstone. The uppermost K1h and the Shangdan Suture Zone (SDSZ) to the north, the is dominated by a sequence of brown-red mudstone- Mianlue Suture Zone (MLSZ) to the south, the Foping Dome sandstone and thickly bedded massive red conglomerate. to the east, and the Qilian Shan to the west-northwest This formation has been interpreted to represent a shallow (Figure 1(a)). The WQLF and SDSZ, which extend NW-SE lacustrine, sandy braided river and alluvial fan environment. for ~800 km, are characterized by early Paleozoic ophiolitic The minimum total thickness of the Donghe Group is ca. rocks that mark the Shangdan Ocean [28]. Since the Mio- 7000 m [39]. cene, the WQLF has been active as a left-lateral strike-slip Early Cretaceous rocks in the Huicheng Basin were fault. With an estimated slip rate during the Quaternary of folded and thrust faulted (Figures 2(b) and 2(c)). The entire 2–3 mm/yr [30], the WQLF is a major fault that connects basin is an open synclinorium in the hanging wall of the the seismically active Qilian Shan in the west to the tectoni- Mianlue Suture Zone (Figure 3). Limbs of the synclinorium ° ° cally active Weihe Basin, which is located next to the dip 40 –60 (Figures 2(c) and 3). The restored thickness of relatively stable Longzhong Basin (Figure 1(b)). The north- Cretaceous strata and the uncertainties concerning fault dips dipping MLSZ lies north of an arcuate thrust that was active in depth conspire to give the minimum and maximum during the middle-late Triassic collision between the North shortening estimates of ca. 10–20 km (Craddock et al. [40] China Block and the South China Block [23]. Along the and this study). WQB, the elevation gradually decreases toward the east. Four arcuate south-vergent thrust faults are found in the 3. (U-Th)/He Thermochronology WQB (Figure 1(a)) [33]. The Lintan-Tanchang Fault (LTF), which cuts Devonian sandstones and Carboniferous shales, 3.1. Samples and Methods. Low-temperature thermochrono- is intruded by Triassic granitoids. Intensely folded lower to logical data derived from vertical elevation/depth profiles

Downloaded from http://pubs.geoscienceworld.org/gsa/lithosphere/article-pdf/doi/10.2113/2020/8294751/5293396/8294751.pdf by guest on 30 September 2021 Lithosphere 3

102° 104° 106° 108°E Legend Quaternary Cretaceous Neogene Triassic Paleogene Paleozoic Jurassic Precambrian Mesozoic plutons Paleozoic plutons 35 ° N Suture zone rust fault Anticline/syncline axis 34 ° 33 ° 32 °

102° 104° 106° 108° 110° 112 º 114°E

Figure 1: (a) Generalized tectonic map of the West Qinling Belt (based on our recent mapping and Dong et al. [20] and Zheng et al. [71]). (b) Lithospheric-scale model of the Oligocene (not to scale). Information on crustal structures and the depth of the Moho is adapted from Wang et al. (2011) and Guo et al. [31]. Information on magmatism is from Yu et al. [69] and Liu et al. [24]. Note that the West Qinling Fault is considered the northeastern boundary of the Tibetan Plateau [12]. Fault: SDSZ: Shangdan Suture Zone; MLSZ: Mianlue Suture Zone; WQLF: West Qinling Fault; LTF: Lintan-Tanchang Fault; GDF: Guanggai Shan-Die Shan Fault; LJF: Liangdang-Jiangluo Fault; CXF: Chenxian Fault; HGF: Huaqiao-Ganquan Fault; DWF: Diebu-Wudu Fault; KMF: Kangxian-Wenxian-Maqu Fault; YQF: Yangpingguan-Qingchuan Fault; LMSF: Longmen Shan Fault; SHF: Southern Hannan Fault; AKF: Ankang Fault; WFF: Wafangdian Fault; ZBF: Zhenba Fault. Basin: HCB: Huicheng Basin; SZB: Sikouzi Basin; TGB: Tange Basin; TCB: Tanchang Basin.

could provide constraints on the thermal and exhumation 4. Results history [10, 14, 41, 42]. Apatite (U-Th)/He (AHe) low- temperature thermochronology has a partial retention zone We obtained 60 single-grain ages from 12 samples. Typically, ° (PRZ) from 55 to 80 C [43]. Assuming an average regional five single-grain analyses were used to calculate mean ages ° geothermal gradient of 25 C/km [44], depths of the PRZ (Table DR1). Age uncertainties are reported as the 2σ stan- range from ca. 2 to 3 km. AHe data provide information on dard error of replicate analyses for individual samples using the cooling path through the PRZ, and rapid cooling might an average standard deviation for each data subgroup [14]. be interpreted as a result of uplift and following unroofing of 14 samples with replicate ages that exceeded 30% standard rocks in response to tectonism. We collected seven samples deviation were rejected because we considered the mean age from medium-grained lower Cretaceous sandstone (KB of these samples to be less well constrained than the rest of profile) across the Huicheng Basin for apatite (U-Th)/He the dataset which had much higher reproducibility (Table analysis (Figure 3). These samples were collected along a DR1). Factors that cause age dispersion in the AHe system roadcutthatrunperpendiculartothebasinalongadistance may include radiation damage, crystal size, and U and Th of >20 km, exposing a ~7 km section. The sampling strategy zoning [43, 47–49]. These effects become more pronounced was to collect a full profile covering the largest paleodepth for samples that cool slowly through the apatite partial range of the hanging wall of the Huaqiao-Ganquan Fault retention zone [43, 50]. AHe age-eU or 4He plots show (HGF) in order to use AHe ages to constrain the exhuma- positive correlations for TP3, TP4, and KB5 (Figs DR1 tion of the hanging wall of this thrust. We use the total and DR2), implying a role of radiation damage on helium thickness of Cretaceous strata to estimate the paleodepth diffusion in apatite [48]. Most AHe age-eU or 4He plots of each sample. Additionally, five samples from a single do not show any correlation (Figs DR1 and DR2). Triassic pluton (TP profile) in the footwall of the HGF were Apatite (U-Th)/He (AHe) ages from the TP profile range dated with AHe. Five samples were collected from a ca. between 100 Ma and 45 Ma, which are younger than pluton 1 km vertical transect (Figure 3). Based on our field observa- crystallization ages (ca. 210 Ma) indicating complete reset- tions, the two sampling profiles (TP and KB profiles) are ting of the AHe system [20, 42]. AHe ages on the vertical pro- not cut by brittle faults (Figure 3). file increase with elevation with a distinct change in the Five grains were analyzed from each sample at the School apparent exhumation rate at ca. 1400 m (Figure 4(a) and of Earth Sciences, the University of Melbourne, and Com- Table DR1). Below 1400 m elevation, analyses define a rela- monwealth Scientific and Industrial Research Organization, tively steep age/elevation gradient with an increase from 62 Australia. Details of the methodology are presented in the to 45 Ma (Figure 4(a) and Table DR1). Above 1400 m, analy- Supplementary Materials (available here) [45, 46]. ses define a gentle age/elevation gradient with ages increasing

Downloaded from http://pubs.geoscienceworld.org/gsa/lithosphere/article-pdf/doi/10.2113/2020/8294751/5293396/8294751.pdf by guest on 30 September 2021 4 Lithosphere

40 m

(a)

45 m

(b)

50 m

(c)

Figure 2: Field photographs from the Huicheng Basin (for locations, see Figure 3). (a) An angular unconformity between early Cretaceous conglomerate of the Huaya Formation (K1h) and overlying Paleogene conglomerate of the Guyuan Group (E). (b) Terrestrial deposits of the Tianjiaba Formation (K1t) thrust over Silurian phyllite (S) along the Huaqiao-Ganquan Fault (HGF). (c) NE-SW syncline developed in the Huaya Formation (K1h).

from 66 to 100 Ma (Figure 4(a) and Table DR1). In the TP monotonically with depth, ranging between ca. 40 Ma and profile, age-elevation relationship defines a gentle gradient 25 Ma (Figure 4(b) and Table DR1). The slope of the age- from ca. 100 to 50 Ma, which is consistent with slow elevation relationship suggests an apparent exhumation rate exhumation. 0.225 km/Myr during the Eocene. Given the thickness (ca. 7 km) of the Donghe Group and The Bayesian transdimensional Markov Chain Monte fi the presence of coal seams in the lower part of K1t, we suggest Carlo method was applied to the TP and KB pro les, using that the KB profile could have been buried to completely the QTQt program (v. 5.4.0) [51]. Data that were deemed anneal the apatite (U-Th)/He system and totally reset the inappropriate for inverse thermal modeling were excluded AHe age (e.g., [42]). Seven samples from the KB profile with [47, 48], and helium diffusion in apatite is modeled using a narrow range of late Eocene age range from 40 to 25 Ma the diffusion parameters of Farley [43]. Models represent (Figure 4(b) and Table DR1), much younger than its 300,000 iterations, with the first 150,000 iterations used to stratigraphic ages. In the KB profile, AHe ages decrease stabilize or burn in the inversion process and the rest of the

Downloaded from http://pubs.geoscienceworld.org/gsa/lithosphere/article-pdf/doi/10.2113/2020/8294751/5293396/8294751.pdf by guest on 30 September 2021 Lithosphere 5

SE TP section HGF KMF MLSZ (km) Erosion 1 KB section 3 2 2 4 LJF 6 7 5 ++ 5 B 1 2 3 4 +++ 1 E A C K1z +++

K h K1t Pt2-3 1 ++++ 0 ++++ Triassic S –1 pluton Ar-Pt1 D T S

0km15

Figure 3: Cross-section of the Huicheng Basin (for the location, see Figure 1) and (U-Th)/He sample locations (yellow dots). White dots indicate locations of field photographs shown in Figure 2. The KB section is the Cretaceous basin profile and the TP section is the Triassic pluton profile. Abbreviations of fault names are as in Figure 1.

iterations used to form the posterior ensemble [51]. Explor- 5. Discussion atory runs using larger numbers of iterations did not alter the inverse thermal model results. Geological constraints used 5.1. Onset of the Huaqiao-Ganquan Thrust Fault. In a thrust for modeling include (1) a present-day temperature of 10 ± 10 faulting system, uplift and accelerated erosion of the hanging ° ° C; (2) a present geothermal gradient of 35 ± 25 C/km [44]; (3) wall would result in enhanced exhumation and cooling, which ° the initial temperature 90 ± 20 Cat80 ± 10 Ma for the TP pro- could be reflected by low-temperature thermochronologic file, according to published apatite fission track data [4, 25]; data [10, 14, 42, 48, 56, 57]. Contrasting cooling histories of ° and (4) the initial temperature constraint at 240 ± 10 Cat the TP and KB profiles show the initial rapid cooling events 110 ± 10 Ma for the KB profile according to the regional as a response to the onset of rapid unroofing during the geothermal gradient, maximum sedimentary thickness, and middle-late Eocene (ca. 45–35 Ma) thrust faulting on the maximum burial age of the Huicheng Basin [37, 44, 52, 53]. Huaqiao-Ganquan Fault (HGF) following an extended period Thermal history modeling for five samples from the TP of slow cooling during late Mesozoic to Paleocene time. profile indicates a protracted late Cretaceous cooling at a rate The TP profile appears to have resided longer in the par- ° of ca. 0.5–1 C/Ma, followed by the early Cenozoic accelerated tial retention zone and has a different thermal history when ° cooling at a rate of ca. 2 C/Ma (Figure 4(c)). Modeling for the compared to the KB profile. Considering that samples are KB profile results in a history of temperature offset between adjacent to major thrust faults (KMF and MLSZ) where the uppermost and lowermost samples. The cooling history moderate hydrothermal fluid activity might have occurred of the KB profile reveals episodic phases of cooling since late (Figure 3), cooling ages may reflect the influence of local Cretaceous time, including a relatively prolonged slow hydrothermal activities rather than possible regional cooling cooling during late Cretaceous and Paleocene time (ca. [26, 27]. This is consistent with a proposed slow cooling from ° 2–3 C/Ma), a distinct phase of relatively rapid cooling at the late Cretaceous to ca. 40–50 Ma for the Huicheng Basin ° ca. 9 C/Ma during the middle-late Eocene, and followed and its adjacent region [4]. Second, the closure temperature by a Neogene-Quaternary almost thermal quiescence with of AFT is higher than that of the apatite (U-Th)/He method. ° minor cooling (ca. 0.5–1 C/Ma). Modeled ages fit reason- We suggest that the TP apatite (U-Th)/He age versus eleva- ably well with observed data (Figures 4(a) and 4(b)). tion profile marks the rapid Paleocene cooling that occurred In summary, modeling that results from two profiles in the hanging wall of the regional major thrust faults (KMF show episodic cooling. First, pre-Paleocene cooling appears and MLSZ). This is consistent with the accelerated exhuma- to be slow, which is consistent with previous works in the tion in the northwestern WQB during the Eocene [14]. WQB [4, 14, 25, 54, 55]. Second, the initiation of the acceler- Differential rates of cooling during ca. 45–35 Ma between ated exhumation is refed to as early as Eocene time (ca. the KB and TP profiles suggest that the former experienced 50 Ma), with a possible rapid cooling phase at middle-late more pronounced cooling. Assuming an average geothermal ° Eocene time (ca. 45–35 Ma). Last, exhumation since the gradient of ca. 25 ± 10 C/km in the WQB, the present value Oligocene seems to be less constrained. This cooling stage for the study area, the difference in cooling is equivalent to is ambiguous because it only involves relatively lower a ca. 2–6 km exhumation, which is similar to the upward off- ° temperatures (<30 C), to which the AHe method is not set and throw of less than 6 km of the KB profile relative to sensitive [42]. the TP profile across the HGF (Figure 3). Due to strike-slip

Downloaded from http://pubs.geoscienceworld.org/gsa/lithosphere/article-pdf/doi/10.2113/2020/8294751/5293396/8294751.pdf by guest on 30 September 2021 6 Lithosphere

1800 0 TP proﬁle KB proﬁle

1400 –2000

Elevation (m) 1000

Depth (km) –4000 20 40 60 80 100 120 250 Age (Ma) –6000 (a)

0 20 30 40 50 60 70 80 Age (Ma) 100 Legend Mean age-apatite 200 Included replicate Excluded replicate

Temperature (ºC) 300 Mean age error (2σ) TP proﬁle (b) 400 80 60 40 20 0 Crustal shortening (~20km) Age (Ma)

(c) Cooling of 60-80ºC 0 6 40Ma since -45Ma 100 via thrust-induced 4 200 30Ma erosion 20-25ºC/km 300 2 100Ma 400 Temperature (ºC) 60Ma Elevation (km) 0 500 Cretaceous KB proﬁle

~45-35Ma Triassic pluton strata 100 80 60 40 20 0 –2 Age (Ma)

(d) (e)

Figure 4: (a) Age versus elevation data (in 2σ errors) for the Triassic pluton profile (TP profile). (b) Age versus depth data for the Cretaceous basin profile (KB profile). Horizontal error bars represent mean age 2σ uncertainties based on single-grain replicate ages. Vertical error bars represent uncertainties on estimates of fault plane depth. (c, d) Time-temperature history from QTQt modeling [51]. Initial constraints are shown by black solid boxes. The blue line corresponds to the uppermost sample, with the blue dashed lines indicating the 95% confidence interval for this sample. The orange line corresponds to the lowermost sample, with the orange dashed lines indicating the 95% confidence interval for this sample. The models show a possible cooling at 45–35 Ma. (e) Cross-section across the HGF showing fault-related folding of Cretaceous rocks and the erosion of 3–5 km of the hanging wall rocks (equivalent to 60–80°C of cooling). Restoration of deformed Cretaceous basins in the WQB suggests ~10–20 km of shortening (Craddock et al. [40] and this study). faulting in the region, there is much uncertainty about north-south shortening in the WQB (Figure 3). The fault amounts of shortening across the Huicheng Basin/or some plane of the HGF dips at >30°, and the cutoff angle in the region. We tentatively constrain a minimum magnitude of hanging wall strata is relatively low (Figure 2(b)). We suggest shortening through area balancing of early Cretaceous a fault-propagation fold developing in the hanging wall over sequences, using the flexural slip folding model and line- a thrust ramp (Figure 4(e)) [58]. In summary, combined AHe length constant method. The inferred amount of shortening age-depth data suggest rapid cooling since ~45 Ma, corre- is ca. 20 km shortening. Considering an average magnitude sponding to the removal of ca. 3–5 km of rocks (Figure 4(e)). of shortening of ca. 7–10 km across the Jungong Basin in the northwestern part of the WQB [40], we estimate that 5.2. Timing of Deformation in the West Qinling Belt. During the Cretaceous rocks were subjected to ca. 10–20 km of the late Cretaceous to Eocene (ca. 100–50 Ma), the TP profile

Downloaded from http://pubs.geoscienceworld.org/gsa/lithosphere/article-pdf/doi/10.2113/2020/8294751/5293396/8294751.pdf by guest on 30 September 2021 Lithosphere 7

is characterized by a slow exhumation (Figures 4(a) and Taibai Shan (northeastern WQB) [60] and Ganjia Shan 4(b)), consistent with a documented regional peneplanation (northwestern WQB) [14] have undergone rapid exhuma- period. First, the absence of the late Cretaceous and Paleo- tion since ca. 45–50 Ma, causing the development of topogra- cene sedimentary deposits along the Qinling Belt implies that phy above the WQLF. Second, a shift in provenance in the this orogenic belt experienced erosion during a period of time Lanzhou Basin from the eastern Qilian Shan to the WQB lacking tectonism [22, 40]. Second, apatite fission track data suggests that the deformation and topographic growth might suggest slow cooling from the late Cretaceous to ca. 55 Ma have started in the late Eocene [12]. Third, paleomagnetic for the Taibai Shan, northwestern Qinling Belt [55]. Third, data indicate that Eocene sedimentary successions in the ° apatite fission track data show slow cooling (ca. 2 C/m.y.) northeastern Tibetan Plateau were subsequently subjected in the interior of the Daba Shan (southern Qinling Belt), with to clockwise rotation in response to the growth of the WQB ca. 2 km of exhumation from the late Cretaceous to Paleocene (Figure 5(a)) [59, 61]. Fourth, the appearance of detritus shed (Li et al., 2014). Fourth, the Wudang Massif (eastern Qinling from mountain ranges suggests the development of high Belt) is argued to have experienced tectonic quiescence for at topography. Therefore, the appearance of WQB and Kunlun least 50 Myr (late Cretaceous to Paleocene) [25]. From satel- Shan detritus from the Lanzhou-Xining Basin and Qaidam lite imagery, we could identify a low-relief erosion surface Basin at ca. 25–30 Ma (Honggou section) could be related that cuts across Mesozoic and older rocks. We note this to the WQB and Kunlun Shan tectonic uplift since the late planation surface on the basis of the topographic slope (ca. Eocene [9, 12, 16]. Fifth, the Songpan-Ganzi Terrane [62], ° 10–15 ) over contiguous areas greater than 25–30 km2 Longmen Shan [57], and Micang Shan (south of the WQB) (Figure 1(b) in Clark et al. [14]). A low-relief geomorphic [52] experienced accelerated exhumation during the Eocene, erosion surface across the WQLF is also identified and as indicated by cooling ages (Figure 5(a)). Sixth, 40Ar/39Ar argued to have formed since the late Cretaceous [14]. Collec- geochronological data of granitoids from the East Kunlun tive evidence indicates that the geomorphology of the Fault suggest that rapid growth of the Kunlun range started Qinling Belt was initially controlled by long-term weathering at ~30 Ma, in response to the rising topography of the Kun- and denudation, characterized by peneplanation that might lun range [14, 63]. have formed low-amplitude, long-wavelength topography Spatial-temporal variations in the nature of orogenies in since the late Cretaceous. the WQB and surrounding areas may be linked to the growth Since the Eocene, mountain building events have devel- of the Tibetan Plateau (Figure 5(a)). The ongoing continent- oped in the Qinling Belt [12]. Within the WQB, during the continent collision may have reactivated preexisting faults in early Cenozoic, the initiation of localized thrust-induced central Asia. Continuous crustal thickening and uplift south rapid cooling [14] and 40Ar/39Ar age of fault gouge [15] lead of the WQLF at ca. 30 Ma may have resulted in northward to the proposal of an Eocene onset of contractional tectonism thinning of sediments in the Linxia-Xunhua Basin along the north portion of the WQB (Figure 5(a)). Similarly, (Figure 5(a)) [11, 41]. During the same period, the Xining- rapid cooling since ~45 Ma is recorded along the southeast- Lanzhou Basin records shifting sedimentation rates, paleo- ern edge of the WQB. A major piece of the evidence for the current directions, and detrital zircon age populations Eocene deformation comes from the Oligocene depositional (Figure 5(a)) [12, 16]. These changes are attributed to the history (Guyuan Group) in the Oligocene [21, 34–36]. Our pulsed growth of the WQB at ca. 30 Ma. In contrast to the data also argue for an Eocene exhumation along the south- southeastern Longzhong Basin, the Sikouzi Basin started to eastern WQB (Huicheng Basin). Meanwhile, similarities in develop during the Eocene in extensional half-grabens [64]. Cretaceous deformation are observed among basins in the Collective evidence suggests that during the Oligocene, the WQB, including the Jungong Basin in the northwestern WQB and the area to the south might have already formed a WQB [40] and Tanchang Basin in the middle of the WQB high plateau, with the Longzhong Basin (sensu lato)beinga [59]. Widespread Cretaceous deposits due to contractional foreland basin associated with this topography (Figure 5(a)). deformation of certain origin occurred within the WQB in Integrating our results with previous studies allows us to the early Cenozoic (ca. 45–35 Ma). reconstruct the paleolandscape of the northeastern Tibetan To orogenic scales, the angular unconformity between Plateau. Thermochronological data from the Jishi Shan, Laji lower Cretaceous and Eocene is ca. 45–35 Ma in the interior Shan [56], Liupan Shan [65], Min Shan [52], and Longmen WQB (Figure 1); meanwhile, the disconformity between the Shan [57] further indicate that rapid exhumation and river lower Cretaceous and Eocene strata in the East Qinling Belt incision [66] occurred during the Miocene (Figure 5(b)). which indicate that Qinling Belt is characterized with seg- We compile exhumation data in the northeastern Tibetan mentation and the geodynamic setting variations for the Plateau with information on the distribution and thickness West and East segment (Figure 1(a)). These results indicate of Miocene to Quaternary deposits. We exclude data on uplift that the middle-late Eocene crustal shortening probably rep- and deposits since the Neogene [11, 12, 16, 33, 64, 67] and resents a phase of hinterland regional deformation that was restore paleolandscape in the northeastern Tibetan Plateau. reactivated by the growth of the Tibetan Plateau. This reconstruction shows that the WQLF was the northeastern boundary of the Tibetan Plateau during the Oligocene 5.3. Implications for Deformation of the NE Tibetan Plateau. (Figure 5(a)). Several lines of evidence suggest that the northeastern Thermochronological data from the northeastern Tibetan Plateau might experience crustal thickening at ca. Tibetan Plateau and the evidence from the foreland basin 50–30 Ma. First, thermochronological data indicate that are consistent with the northward propagation of thrusts

Downloaded from http://pubs.geoscienceworld.org/gsa/lithosphere/article-pdf/doi/10.2113/2020/8294751/5293396/8294751.pdf by guest on 30 September 2021 8 Lithosphere

LZB: Lanzhou-Xining Basin Legend XHB: Xunhua-Linxia Basin Vertical-axis rotation SZB: Sikouzi Basin Movement direction LXB: Linxia Basin Exhumantion Provenance change

(a) Fault initiation Basin formation Increased sedimentation rate Strike-slip fault

rust fault

Normal fault

WSB: Wushan Basin 4000 HCB: Cenozoic Huicheng Basin AFT: apatite ﬁssion track AHe/ZHe: apatite and zircon (U-)/He Elevation(m) 600

(b)

Figure 5: Compilation of faults, basins, mountains, magmatism, and exhumation ages in the WQB during (a) 50–30 Ma and (b) Neogene. Abbreviations of fault names are as in Figure 1. Information on the growth and rotation of the northeastern Tibetan Plateau (orange arrows) is from Tapponnier et al. [2], Dupont-Nivet et al. [19], Yu et al. [72], Li et al. [73], and Zhang et al. [74]. Data are derived from the following: (1) Fang et al. [16]; (2) Wang et al. [12]; (3) Lease et al. [41]; (4) Fang et al. [11]; (5) Wang et al. [75]; (6) Clark et al. [14]; (7) Duvall et al. [15]; (8) Liu et al. [60]; (9) Mock et al. [63]; (10) Roger et al. [62]; (11) Wang et al. (2012); (12) Tian et al. [46]; (13) Yang et al. [25]; (14) Duvall et al. [76]; (15) Yu et al. [77]; (16) Lease et al. [56]; (17) Zheng et al. [65]; (18) Wang et al. (2012); (19) Liu et al. [24]; (20) Yu et al. [69]; (21) Zhang and Xue [36]; (22) Tian et al. [52]; (23) Tian et al. [78]; and (24) Clark et al. [13].

Downloaded from http://pubs.geoscienceworld.org/gsa/lithosphere/article-pdf/doi/10.2113/2020/8294751/5293396/8294751.pdf by guest on 30 September 2021 Lithosphere 9

during the Paleogene. During the Miocene, the onset of east- Supplementary Materials ward extrusion, in addition to the continued N-S contraction, may have led to the growth of N-S-striking mountains (e.g., (U-Th)/He thermochronology methods. Figure DR1: plots of ff the Jishi Shan) [56] and the development of pull-apart basins AHe dates versus e ective uranium concentration (eU). (e.g., the Wushan Basin) along the WQLF (Figure 5(b)) [30]. Figure DR2: plots of AHe dates versus 4He for data. Table Eastward crustal extrusion might reactivated long-lived lith- DR1: results for apatite (U-Th)/He thermochronology. ospheric zones of weakness for evacuating low-volume (Supplementary Materials) asthenospheric melts and the formation of Miocene (ca. 20 Ma) mafic-ultramafic magmatism [24, 68, 69]. Shear wave References velocity data show that low-velocity mantle lithosphere and fi “ asthenosphere exist at depths of 90–150 km beneath the [1] L. H. Royden, B. C. Burch el, and R. D. van der Hilst, The geological evolution of the Tibetan Plateau,” Science, vol. 321, central Tibetan Plateau and the WQB [70]. Altogether, they no. 5892, pp. 1054–1058, 2008. indicate both northward and eastward lateral growth of the [2] P. Tapponnier, X. Zhiqin, F. Roger et al., “Oblique stepwise northeastern Tibetan Plateau (Figure 5(b)). rise and growth of the Tibet Plateau,” Science, vol. 294, no. 5547, pp. 1671–1677, 2001. 6. Conclusions [3] W.-J. Zheng, P.-Z. Zhang, W.-P. Ge et al., “Late Quaternary slip rate of the South Heli Shan Fault (northern Hexi Corridor, Low-temperature thermochronologic data from the West NW China) and its implications for northeastward growth of Qinling Belt help constrain thermal histories across a major the Tibetan Plateau,” Tectonics, vol. 32, no. 2, pp. 271–293, thrust system in the northeastern Tibetan Plateau. In the 2013. Huicheng Basin, apatite (U-Th)/He ages from the hanging [4] E. Enkelmann, L. Ratschbacher, R. Jonckheere et al., “Cenozoic wall (Cretaceous sedimentary strata) and the footwall wall exhumation and deformation of northeastern Tibet and the (Triassic pluton) of the Huaqiao-Ganquan thrust fault reveal Qinling: is Tibetan lower crustal flow diverging around the an initial rapid cooling event that occurred at ca. 45–35 Ma. Sichuan Basin?,” Geological Society of America Bulletin, Contrasting thermal histories were also observed across the vol. 118, no. 5-6, pp. 651–671, 2006. fault. Our observations were interpreted as results of thrust- [5] P. Molnar, P. England, and J. Martinrod, “Mantle dynamics, ing in the Eocene time (ca. 45–35 Ma) with a possible uplift of the Tibetan Plateau, and the Indian Monsoon,” decade-kilometer crustal shortening. The Eocene age thrust- Reviews of Geophysics, vol. 31, no. 4, pp. 357–396, 1993. ing is broadly consistent with published sediment record and [6] J. Pang, J. Yu, D. Zheng et al., “Neogene expansion of the fault gouge data that are thought to reflect deformation dis- Qilian Shan, North Tibet: implications for the dynamic evolu- tributed across the entire West Qinling Belt. This result clar- tion of the Tibetan Plateau,” Tectonics, vol. 38, no. 3, pp. 1018– ifies that the northeastern Tibetan Plateau experienced 1032, 2019. deformation and possible mountain uplift in the Eocene, [7] E. R. Sobel and T. A. Dumitru, “Thrusting and exhumation which might reflect widespread crust shortening associated around the margins of the western Tarim basin during the ” with the initial growth of the Tibetan Plateau. India-Asia collision, Journal of Geophysical Research: Solid Earth, vol. 102, no. B3, pp. 5043–5063, 1997. [8] A. Yin and T. M. Harrison, “Geologic evolution of the Data Availability Himalayan-Tibetan Orogen,” Annual Review of Earth and – This data in the manuscript is our new data and is tested in Planetary Sciences, vol. 28, no. 1, pp. 211 280, 2000. [9] W. Wang, W. Zheng, P. Zhang et al., “Expansion of the the School of Earth Sciences, the University of Melbourne, ” and Commonwealth Scientific and Industrial Research Orga- Tibetan Plateau during the Neogene, Nature Communica- tions, vol. 8, no. 1, article 15887, 2017. nization, Australia. Details of the methodology and results are presented in the supplementary materials. [10] D. Zheng, M. K. Clark, P. Zhang, W. Zheng, and K. A. Farley, “Erosion, fault initiation and topographic growth of the North Qilian Shan (northern Tibetan Plateau),” Geosphere, vol. 6, Conflicts of Interest no. 6, pp. 937–941, 2010. “ fl [11] X. Fang, C. Garzione, R. van der Voo, J. Li, and M. Fan, Flex- The authors declare that they have no con icts of interest. ural subsidence by 29 Ma on the NE edge of Tibet from the magnetostratigraphy of Linxia Basin, China,” Earth and Plan- Acknowledgments etary Science Letters, vol. 210, no. 3–4, pp. 545–560, 2003. [12] W. Wang, P. Zhang, C. Liu et al., “Pulsed growth of the West This work is supported by the Second Tibetan Plateau Qinling at ~30 Ma in northeastern Tibet: evidence from Lan- Scientific Expedition and Research Program (STEP) zhou Basin magnetostratigraphy and provenance,” Journal of (2019QZKK0901), National Key Research and Development Geophysical Research: Solid Earth, vol. 121, no. 11, pp. 7754– Program of China (2017YFC1500101), National Natural 7774, 2016. Science Foundation of China (41590861, 41872204), and [13] K. E. Dayem, P. Molnar, M. K. Clark, and G. A. Houseman, International Program for PhD Candidates, Sun Yat-sen “Far-field lithospheric deformation in Tibet during continen- University. We thank Dr. Zhi-Gang Li, Dr. Chuang Sun, tal collision,” Tectonics, vol. 28, no. 6, article TC6005, 2009. Dr. Yang Wang, and PhD student Gan Cheng for comments [14] M. K. Clark, K. A. Farley, D. W. Zheng, Z. C. Wang, and A. R. and encouragement. Duvall, “Early Cenozoic faulting of the northern Tibetan

Downloaded from http://pubs.geoscienceworld.org/gsa/lithosphere/article-pdf/doi/10.2113/2020/8294751/5293396/8294751.pdf by guest on 30 September 2021 10 Lithosphere

Plateau margin from apatite (U–Th)/He ages,” Earth and NE Tibetan plateau, China: implications for middle Miocene Planetary Science Letters, vol. 296, no. 1–2, pp. 78–88, 2010. tectonics of the West Qinling fault zone,” Journal of Asian Earth [15] A. R. Duvall, M. K. Clark, B. A. van der Pluijm, and C. Li, Sciences,vol.44,no.1,pp.189–202, 2012. “Direct dating of Eocene reverse faulting in northeastern Tibet [31] X. Guo, R. Gao, S. Li et al., “Lithospheric architecture and using Ar-dating of fault clays and low-temperature thermo- deformation of NE Tibet: new insights on the interplay of chronometry,” Earth and Planetary Science Letters, vol. 304, regional tectonic processes,” Earth and Planetary Science Let- no. 3–4, pp. 520–526, 2011. ters, vol. 449, pp. 89–95, 2016. [16] X. Fang, Y. Fang, J. Zan et al., “Cenozoic magnetostratigraphy [32] C. Wang, R. Gao, A. Yin et al., “A mid-crustal strain-transfer of the Xining Basin, NE Tibetan Plateau, and its constraints on model for continental deformation: a new perspective from paleontological, sedimentological and tectonomorphological high-resolution deep seismic-reflection profiling across NE evolution,” Earth-Science Reviews, vol. 190, pp. 460–485, 2019. Tibet,” Earth and Planetary Science Letters, vol. 306, no. 3–4, [17] A. Yin, Y. Q. Dang, L. C. Wang et al., “Cenozoic tectonic evo- pp. 279–288, 2011. lution of Qaidam basin and its surrounding regions (Part 1): [33] GBGMR (Gansu Bureau of Geology and Mineral Resources), the southern Qilian Shan-Nan Shan thrust belt and northern Regional Geology of Gansu Region (in Chinese with English Qaidam basin,” Geological Society of America Bulletin, summary), Geological Publishing House, Geological Publishing vol. 120, no. 7-8, pp. 813–846, 2008. House, Beijing, 1989. [18] G. Zhuang, J. K. Hourigan, B. D. Ritts, and M. L. Kent-Corson, [34] L. T. Yeh and S. C. Kwan, Geology of Central and Southern “Cenozoic multiple-phase tectonic evolution of the northern Kansu (in Chinese with English Abstract), The National Geo- Tibetan Plateau: constraints from sedimentary records from logical Survey of China, Chongqing, China, 1944. Qaidam basin, Hexi Corridor, and Subei basin, northwest [35] SBGMR (Shanxi Bureau of Geology and Mineral Resources), China,” American Journal of Science, vol. 311, no. 2, pp. 116– Preliminary geologic map of Chengxian, scale 1:200, 000, 1968. 152, 2011. [36] Y. Zhang and X. Xue, “Features and geologic age of stratigra- [19] G. Dupont-Nivet, S. Dai, X. Fang et al., “Timing and distribu- phy in Longjiagou Basin, Wudu, Gansu province,” Northwest tion of tectonic rotations in the northeastern Tibetan plateau,” Geosciences, vol. 15, no. 2, pp. 27–31, 1994. in Investigations into the Tectonics of the Tibetan Plateau, [37] L. M. Ji, H. Y. Lei, and X. Fang, “Discovery of sporo-pollen fos- vol. 444, Geological Society of America, 2007. sils from the Donghe Group of the Huicheng Basin and their [20] Y. Dong, Z. Yang, X. Liu et al., “Mesozoic intracontinental stratigraphic significance,” Journal of Stratigraphy, vol. 21, orogeny in the Qinling Mountains, central China,” Gondwana no. 1, pp. 32–38, 1997. – Research, vol. 30, pp. 144 158, 2016. [38] Z. Zhang, “Spore-pollen assemblage of the Donghe group in [21] Y. Zhai and T. Cai, “The tertiary system of Gansu Province,” the Huixian-Chengxian Basin and their stratigraphic signifi- Gansu Geology, vol. 2, 1984. cance (in Chinese with English abstract),” Northwest Geosci- [22] Q.-R. Meng and G.-W. Zhang, “Geologic framework and tec- ence, vol. 5, pp. 101–114, 1982. tonic evolution of the Qinling orogen, central China,” Tectono- [39] W. T. Liang, Intracontinental tectonic characteristics and evo- physics, vol. 323, no. 3–4, pp. 183–196, 2000. lution process of the Qinling orogenic belt transition zone, [23] G. Zhang, The Mianlue Tectonic Zone of the Qinling Orogen [Ph.D. thesis], Northwest University, 2009. and China Continental Tectonics, Science Press, Beijing, 2015. [40] W. H. Craddock, E. Kirby, Z. Dewen, and L. Jianhui, “Tectonic [24] D. Liu, Z. D. Zhao, Y. L. Niu, D. C. Zhu, and X. H. Li, “Perov- setting of Cretaceous basins on the NE Tibetan Plateau: skite U-Pb and Sr-Nd isotopic perspectives on melilitite mag- insights from the Jungong basin,” Basin Research, vol. 24, matism and outward growth of the Tibetan Plateau,” Geology, no. 1, pp. 51–69, 2012. vol. 46, no. 12, pp. 1027–1030, 2018. [41] R. O. Lease, D. W. Burbank, B. Hough, Z. C. Wang, and D. Y. [25] Z. Yang, C. B. Shen, L. Ratschbacher et al., “Sichuan Basin and Yuan, “Pulsed Miocene range growth in northeastern Tibet: beyond: eastward foreland growth of the Tibetan Plateau from insights from Xunhua Basin magnetostratigraphy and prove- an integration of Late Cretaceous-Cenozoic fission track and nance,” Geological Society of America Bulletin, vol. 124, (U-Th)/He ages of the eastern Tibetan Plateau, Qinling, and no. 5-6, pp. 657–677, 2012. Daba Shan,” Journal of Geophysical Research: Solid Earth, [42] P. W. Reiners and M. T. Brandon, “Using thermochronology vol. 122, no. 6, pp. 4712–4740, 2017. to understand orogenic erosion,” Annual Review of Earth [26] Z. Ye, J. T. Li, R. Gao et al., “Crustal and uppermost mantle and Planetary Sciences, vol. 34, no. 1, pp. 419–466, 2006. structure across the Tibet-Qinling transition zone in NE Tibet: [43] K. A. Farley, “Helium diffusion from apatite: general behavior implications for material extrusion beneath the Tibetan as illustrated by Durango fluorapatite,” Journal of Geophysical Plateau,” Geophysical Research Letters, vol. 44, no. 20, Research: Solid Earth, vol. 105, no. B2, pp. 2903–2914, 2000. – pp. 10,316 310,323, 2017. [44] S. Hu, H. He, and J. Wang, “Heat flow in the continental area [27] X. Yuan and M. Xue, “Eastern Qinling seismic reflection profil- of China: a new data set,” Earth and Planetary Science Letters, ing,” Acta Geophysica Sinica,vol.37,no.6,pp.749–758, 1994. vol. 179, no. 2, pp. 407–419, 2000. [28] Y. Dong and M. Santosh, “Tectonic architecture and multiple [45] B. Kohn, T. Weissbrod, L. Chung, K. Farley, and S. Bodorkos, orogeny of the Qinling Orogenic Belt, Central China,” Gond- “Low-temperature thermochronology of francolite: insights wana Research, vol. 29, no. 1, pp. 1–40, 2016. into timing of Dead Sea Transform motion,” Terra Nova, [29] M. Mattauer, P. Matte, J. Malavieille et al., “Tectonics of the vol. 31, no. 3, pp. 205–219, 2019. Qinling Belt: build-up and evolution of eastern Asia,” Nature, [46] Y. Tian, B. P. Kohn, C. Zhu, M. Xu, S. Hu, and A. J. W. Gleadow, vol. 317, no. 6037, pp. 496–500, 1985. “Post-orogenic evolution of the Mesozoic Micang Shan foreland [30] Z. Wang, P. Zhang, C. N. Garzione et al., “Magnetostratigraphy basin system, central China,” Basin Research, vol. 24, no. 1, and depositional history of the Miocene Wushan basin on the pp. 70–90, 2012.

Downloaded from http://pubs.geoscienceworld.org/gsa/lithosphere/article-pdf/doi/10.2113/2020/8294751/5293396/8294751.pdf by guest on 30 September 2021 Lithosphere 11

[47] K. A. Farley, R. A. Wolf, and L. T. Silver, “The effects of long the Xining-Lanzhou region, northeastern Tibetan Plateau,” alpha-stopping distances on (U-Th)/He ages,” Geochimica et Journal of Geophysical Research Atmospheres, vol. 109, Cosmochimica Acta, vol. 60, no. 21, pp. 4223–4229, 1996. no. B4, pp. 657–681, 2004. [48] R. M. Flowers, R. A. Ketcham, D. L. Shuster, and K. A. Farley, [62] F. Roger, J. Malavieille, P. H. Leloup, S. Calassou, and Z. Xu, “Apatite (U–Th)/He thermochronometry using a radiation “Timing of granite emplacement and cooling in the Song- damage accumulation and annealing model,” Geochimica et pan–Garzê Fold Belt (eastern Tibetan Plateau) with tectonic Cosmochimica Acta, vol. 73, no. 8, pp. 2347–2365, 2009. implications,” Journal of Asian Earth Sciences, vol. 22, no. 5, – [49] R. A. Ketcham, “Forward and inverse modeling of low- pp. 465 481, 2004. temperature thermochronometry data,” Reviews in Mineral- [63] C. Mock, N. O. Arnaud, and J.-M. Cantagrel, “An early ogy and Geochemistry, vol. 58, no. 1, pp. 275–314, 2005. unroofing in northeastern Tibet? Constraints from 40Ar/39Ar [50] W. R. Guenthner, P. W. Reiners, R. A. Ketcham, L. Nasdala, thermochronology on granitoids from the eastern Kunlun and G. Giester, “Helium diffusion in natural zircon: radia- range (Qianghai, NW China),” Earth and Planetary Science tion damage, anisotropy, and the interpretation of zircon Letters, vol. 171, no. 1, pp. 107–122, 1999. (U-Th)/He thermochronology,” American Journal of Science, [64] W. Wang, E. Kirby, Z. Peizhen et al., “Tertiary basin evolution vol. 313, no. 3, pp. 145–198, 2013. along the northeastern margin of the Tibetan Plateau: evidence [51] K. Gallagher, “Transdimensional inverse thermal history for basin formation during Oligocene transtension,” Geological modeling for quantitative thermochronology,” Journal of Geo- Society of America Bulletin, vol. 125, no. 3-4, pp. 377–400, 2013. physical Research: Solid Earth, vol. 117, no. B2, article B02408, [65] D. Zheng, P. Zhang, J. Wan et al., “Rapid exhumation at ~8Ma 2012. on the Liupan Shan thrust fault from apatite fission-track ther- [52] Y. Tian, R. Li, Y. Tang, X. Xu, Y. Wang, and P. Zhang, “Ther- mochronology: implications for growth of the northeastern ” mochronological Constraints on the Late Cenozoic morpho- Tibetan Plateau margin, Earth and Planetary Science Letters, – – tectonic evolution of the Min Shan, the Eastern Margin of vol. 248, no. 1 2, pp. 198 208, 2006. the Tibetan Plateau,” Tectonics, vol. 37, no. 6, pp. 1733–1749, [66] M. K. Clark, M. A. House, L. H. Royden et al., “Late Cenozoic 2018. uplift of southeastern Tibet,” Geology, vol. 33, no. 6, pp. 525– [53] W. Li, Y. P. Dong, A. L. Guo et al., “Geochronology, geochem- 528, 2005. istry and Sr–Nd–Hf isotopes of mafic dikes in the Huicheng [67] R. O. Lease, “Cenozoic mountain building on the northeastern Basin: constraints on intracontinental extension of the Qinling Tibetan Plateau,” in Toward an Improved Understanding of orogen,” Journal of Asian Earth Sciences, vol. 104, pp. 115–126, Uplift Mechanisms and the Elevation History of the Tibetan 2015. Plateau, vol. 507, pp. 115–127, Geological Society of America, [54] H. Chen, J. M. Hu, G. L. Wu, W. Shi, Y. Y. Geng, and H. J. Qu, 2014. “Apatite fission-track thermochronological constraints on the [68] S. C. Lai, J. F. Qin, and J. Khan, “The carbonated source region pattern of late Mesozoic-Cenozoic uplift and exhumation of of Cenozoic mafic and ultra-mafic lavas from western Qinling: the Qinling Orogen, central China,” Journal of Asian Earth implications for eastern mantle extrusion in the northeastern Sciences, vol. 114, pp. 649–673, 2015. margin of the Tibetan Plateau,” Gondwana Research, vol. 25, [55] B. Heberer, T. Anzenbacher, F. Neubauer, J. Genser, Y. Dong, no. 4, pp. 1501–1516, 2014. and I. Dunkl, “Polyphase exhumation in the western Qinling [69] X. Yu, Z. Zhao, S. Zhou, X. Mo, D. Zhu, and Y. Wang, Mountains, China: rapid early Cretaceous cooling along a “40Ar/39Ar dating for Cenozoic kamafugite from western lithospheric-scale tear fault and pulsed Cenozoic uplift,” Tecto- Qinling in Gansu Province,” Science Bulletin, vol. 51, no. 13, nophysics, vol. 617, pp. 31–43, 2014. pp. 1621–1627, 2006. [56] R. O. Lease, D. W. Burbank, M. K. Clark, K. A. Farley, [70] X. Bao, X. Song, and J. Li, “High-resolution lithospheric struc- D. Zheng, and H. Zhang, “Middle Miocene reorganization of ture beneath Mainland China from ambient noise and earth- deformation along the northeastern Tibetan Plateau,” Geology, quake surface-wave tomography,” Earth and Planetary vol. 39, no. 4, pp. 359–362, 2011. Science Letters, vol. 417, pp. 132–141, 2015. [57] E. Wang, E. Kirby, K. P. Furlong et al., “Two-phase growth of [71] Z. Wen-jun, L. Xing-wang, Y. Jing-xing et al., “Geometry and high topography in eastern Tibet during the Cenozoic,” late Pleistocene slip rates of the Liangdang-Jiangluo fault in Nature Geoscience, vol. 5, no. 9, pp. 640–645, 2012. the western Qinling mountains, NW China,” Tectonophysics, – [58] K. McClay, “Introduction to thrust fault-related folding,” vol. 687, pp. 1 13, 2016. AAPG Memoir, vol. 94, pp. 1–19, 2011. [72] J. Yu, W. Zheng, E. Kirby et al., “Kinematics of late Quaternary [59] B. K. Horton, G. Dupont-Nivet, J. Zhou, G. L. Waanders, slip along the Yabrai fault: implications for Cenozoic tectonics ” R. F. Butler, and J. Wang, “Mesozoic-Cenozoic evolution across the Gobi Alashan block, China, Lithosphere, vol. 8, of the Xining-Minhe and Dangchang basins, northeastern no. 3, pp. 199–218, 2016. Tibetan Plateau: magnetostratigraphic and biostratigraphic [73] X. Li, P. Zhang, W. Zheng et al., “Kinematics of Late Quater- results,” Journal of Geophysical Research Solid Earth, vol. 109, nary slip along the Qishan-Mazhao fault: implications for tec- no. B4, pp. 657–681, 2004. tonic deformation on the Southwestern Ordos, China,” [60] J. Liu, P. Zhang, R. O. Lease et al., “Eocene onset and late Mio- Tectonica, vol. 37, no. 9, pp. 2983–3000, 2018. cene acceleration of Cenozoic intracontinental extension in [74] Y.-P. Zhang, W.-J. Zheng, D.-L. Zhang et al., “Late Pleistocene the North Qinling range–Weihe graben: insights from apatite left-lateral slip rates of the Gulang Fault and its tectonic impli- fission track thermochronology,” Tectonophysics, vol. 584, cations in eastern Qilian Shan (NE Tibetan Plateau), China,” pp. 281–296, 2013. Tectonophysics, vol. 756, pp. 97–111, 2019. [61] G. Dupont-Nivet, B. K. Horton, R. F. Butler, J. Wang, J. Zhou, [75] W. Wang, P. Zhang, E. Kirby et al., “A revised chronology for and G. L. Waanders, “Paleogene clockwise tectonic rotation of Tertiary sedimentation in the Sikouzi basin: implications for

Downloaded from http://pubs.geoscienceworld.org/gsa/lithosphere/article-pdf/doi/10.2113/2020/8294751/5293396/8294751.pdf by guest on 30 September 2021 12 Lithosphere

the tectonic evolution of the northeastern corner of the Tibetan Plateau,” Tectonophysics, vol. 505, no. 1-4, pp. 100– 114, 2011. [76] A. R. Duvall, M. K. Clark, E. Kirby et al., “Low-temperature thermochronometry along the Kunlun and Haiyuan Faults, NE Tibetan Plateau: evidence for kinematic change during late-stage orogenesis,” Tectonics, vol. 32, no. 5, pp. 1190– 1211, 2013. [77] J. Yu, J. Pang, Y. Wang et al., “Mid-Miocene uplift of the northern Qilian Shan as a result of the northward growth of the northern Tibetan Plateau,” Geosphere, vol. 15, no. 2, pp. 423–432, 2019. [78] Y. Tian, B. P. Kohn, S. Hu, and A. J. W. Gleadow, “Synchro- nous ﬂuvial response to surface uplift in the eastern Tibetan Plateau: implications for crustal dynamics,” Geophysical Research Letters, vol. 42, no. 1, pp. 29–35, 2015.

Downloaded from http://pubs.geoscienceworld.org/gsa/lithosphere/article-pdf/doi/10.2113/2020/8294751/5293396/8294751.pdf by guest on 30 September 2021