Late Mesozoic and Cenozoic tectono-thermal history and geodynamic implications of the Great Xing’an Range, NE China

Journal Pre-proofs Late Mesozoic and Cenozoic tectono-thermal history and geodynamic implications of the Great Xing’an Range, NE China Yumao Pang, Xingwei Guo, Xunhua Zhang, Xiaoqing Zhu, Fanghui Hou, Zhenhe Wen, Zuozhen Han PII: DOI: Reference:

S1367-9120(19)30507-3 https://doi.org/10.1016/j.jseaes.2019.104155 JAES 104155

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Journal of Asian Earth Sciences

Received Date: Revised Date: Accepted Date:

28 May 2019 26 August 2019 15 November 2019

Please cite this article as: Pang, Y., Guo, X., Zhang, X., Zhu, X., Hou, F., Wen, Z., Han, Z., Late Mesozoic and Cenozoic tectono-thermal history and geodynamic implications of the Great Xing’an Range, NE China, Journal of Asian Earth Sciences (2019), doi: https://doi.org/10.1016/j.jseaes.2019.104155

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Late Mesozoic and Cenozoic tectono-thermal history and geodynamic implications of the Great Xing’an Range, NE China Yumao Pang1, 3, Xingwei Guo2, 3, *, Xunhua Zhang3, 4, Xiaoqing Zhu2, 3, Fanghui Hou2, 3, Zhenhe Wen2, 3, Zuozhen Han1, 3, **

1

Key Laboratory of Depositional Mineralization and Sedimentary Mineral of Shandong

Province, Shandong University of Science and Technology, Qingdao 266590, China 2

Qingdao Institute of Marine Geology, Qingdao 266071, China

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Laboratory for Marine Mineral Resources, Qingdao National Laboratory for Marine Science

and Technology, Qingdao 266237, China 4

Nanjing Institute of Geology and Mineral Resources, Nanjing 210016, China

Corresponding author at: Qingdao Institute of Marine Geology, Qingdao 266071, China

*

E-mail address: [email protected] Corresponding author at: Shandong University of Science and Technology, Qingdao 266590, China **

E-mail address: [email protected]

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Abstract The Mesozoic–Cenozoic tectonics of Northeastern China involves complex multistage interaction of different tectonic domains and has long been controversial. The tectono-thermal evolutionary history recorded by the widespread outcropped granitoids in the Great Xing’an Range (GXR) may provide significant constraints on the tectonics, illuminating the deep geodynamic process. Here, we present new low-temperature thermochronology data from the GXR, and thus, reconstruct the detailed thermal history. Zircon fission-track dating yielded a group of central ages ranging from 80 ± 4 to 185 ± 10 Ma, while apatite fission-track ages range from 55 ± 3 to 75 ± 5 Ma. The modeled time–temperature paths of all the samples reveal two relatively rapid cooling events at ~100–60 Ma and ~50–0 Ma, and one intervening reheating episode at ~60–50 Ma. The initial uplift, exhumation, and induced cooling events, which represent strong orogenic activity, are related mainly to closure of the Mongol–Okhotsk Ocean in the north and were subsequently influenced by the Paleo-Pacific plate subduction in the east. The evolution of the basin–mountain system consisting of the Songliao Basin and GXR, as well as the accretion, metamorphism, and magmatism at the Northeast Asian continental margin, are all dominated or indirectly influenced by the Paleo-Pacific subduction. This indicates that the Paleo-Pacific subduction had affected the evolution of the GXR to the west since the Jurassic. The significant reheating episode during the Late Paleocene to Eocene may be related to the heat flux derived from asthenosphere upwelling and igneous activity. Key words: Tectono-thermal history; Fission-track dating; Great Xing’an Range; Paleo-Pacific subduction; Geodynamics

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1 Introduction As part of the large-scale igneous belt in East Asia, Northeastern China (NE China) is characterized by widespread volcanic rocks and granitoids, which constitute the largest granitic provinces developed in the Central Asian Orogenic Belt (CAOB) (Li et al., 2017a; Ouyang et al., 2015; Wang et al., 2006; Wu et al., 2011; Zhang et al., 2010; Zhou et al., 2014). The tectonic evolution of the eastern part of the CAOB involved Paleozoic amalgamation of several microcontinental terranes, including the Erguna, Xing’an, Songliao, and Liaoyuan Terranes, which were dominated by the subduction and closure of the Paleo-Asian Ocean (Fig. 1), and Mesozoic accretion of the Jiamusi and Nadanhada Terranes induced by the Paleo-Pacific subduction in the east (Ge et al., 2007; Martynov et al., 2017; Şengör et al., 1993; Wilde et al., 1999; Wu et al., 2011; Xiao et al., 2015; Xu et al., 2019). Collisions of large fragments with mainland Asia since the Triassic have been proposed (Engebretson et al., 1985; Nur and Ben-Avraham, 1977; Yang et al., 2018; Zhou et al., 2014). A brief but significant collision of the Okhotomorsk Block with East Asia during the Late Cretaceous has also been proposed (Yang, 2013; Yang et al., 2015). During the Cenozoic, the Paleo-Pacific subduction initiated substantial calc-alkaline basaltic volcanic events along the Northeast Asian continental margin, such as those of East Sikhote-Alin (i.e., the Russian Far East) (Grebennikov et al., 2016; Jahn et al., 2015; Martynov et al., 2017). The geological record in NE China reveals complex interaction among three tectonic domains involving the Paleo-Asian, the Mongol–Okhotsk, and Paleo-Pacific Oceans, and a series of tectonic scenarios including crustal accretion, microcontinental drift, amalgamation, uplift, and exhumation. It is considered that the Paleo-Pacific subduction plays an important role in the Mesozoic–Cenozoic tectonic evolution of Northeastern Asia (NE Asia) (Engebretson et al., 1985; Liu et al., 2017; Wang et al., 2006; Wilde, 2015; Yang et al., 2019; Zhai et al., 2007). However,

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the temporal-spatial range influenced by the Paleo-Pacific subduction is still unknown (Liu et al., 2017; Sun et al., 2018; Xu et al., 2013). As to NE China, the main controversial issues are the initial time and scenario of the Paleo-Pacific subduction and the deep geodynamics. The orogenic belts and immense volume of Early Cretaceous granitoids in the Great Xing’an Range (GXR) are undoubtedly significant objects related to this tectonic event and can further elucidate its deep geodynamic setting (Dong et al., 2014; Du et al., 2016; Ouyang et al., 2015; Song et al., 2018c; Wilde et al., 2010; Zhang et al., 2008). Several important discoveries have been made during the last decade. Analyses of isotopic data indicate that most granitoids in the eastern CAOB generally contain juvenile crustal material (Kröner et al., 2017; Wu et al., 2003; Wu et al., 2002; Yang et al., 2014; Yang et al., 2017)and thus record significant continental growth and continuous crustal melting during the early stage of the Paleo-Pacific subduction (Liu et al., 2017; Safonova, 2017). Using voluminous geochronological data on granitoids in NE China, Wu et al. (2003) proposed that this subduction resulted in lithospheric thickening and subsequent delamination, and has significantly affected NE Asia since the Jurassic. The evolution of granitoids from I-type to the transitional I-A or A-type indicates the transition from crustal thickening to post-orogenic extensional thinning (Wang et al., 2015). Though petrological and geochemical analyses have contributed to understanding of tectonomagmatic activity in NE Asia, the deep geodynamic process remains controversial. The proposed interpretation of the large-scale Early Cretaceous granitoids in the GXR involves a mantle plume, post-orogenic lithospheric extension, a slab window, back-arc subduction, and deep-sourced water-fluxed melting (Li et al., 2017a). Kincaid and Griffiths (2003) proposed that oceanic lithosphere subduction significantly affects the recycling processes between the mantle and crustal surface, the magmatism, and the thermal evolution. The evolution of the paleo-geothermal field

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under extensional setting is closely related to lithospheric features (Jarvis and McKenzie, 1980; McKenzie, 1978; Toth et al., 1996). Reconstruction of the thermal evolution history recorded by the Phanerozoic granitoids in the GXR is therefore essential to understanding the deep geodynamic process. Moreover, the NNE-SSW trending GXR–Taihang Mountain–Wuling Mountain complex, which stretches along the western Pacific subduction margin, constitutes a prominent gravity gradient lineament (GGL) across East China (Pang et al., 2017b; Windley et al., 2011; Xu, 2007). The western part of this linear gradient belt shows high negative Bouguer anomalies, a thick lithosphere, and low heat flow, whereas the eastern part is characterized by zero to slightly positive gravity anomalies, a delaminated or thin lithosphere, and high heat flow (Li et al., 2014; Li, 2010; Windley et al., 2011). Previous studies proposed that the GGL may indicate that the west boundary is influenced by the Paleo-Pacific subduction (Niu et al., 2015; Xu, 2007). In addition, the formation and evolution of several large Mesozoic–Cenozoic extensional (rifted) sedimentary basins, such as Songliao Basin (SB), Bohai Bay Basin, the Yellow Sea Basin, and the East China Sea Basin, are closely related to the Paleo-Pacific subduction (Wang et al., 2016). Thus, studying the SBGXR basin–mountain system may provide significant insights into the relationship between the tectonic denudation and burial history, and how both relate to the main tectono-thermal events in NE China (Li et al., 2011). In contrast to the well-studied geochronological and geochemical features of the Mesozoic granitoids in the GXR and adjacent areas in NE China, the detailed thermal history has not yet been studied. As an important regional orogenic belt, the GXR is an ideal area to investigate the far-field effect of the Paleo-Pacific subduction because the post-orogenic high-relief regions are susceptible to tectono-thermal events (Hu et al., 2006; Reiners et al., 2003). Low-temperature

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thermochronological dating is an effective approach to reconstructing the time–temperature (t–T) history of near-surface crustal rocks (Donelick et al., 2005; Gallagher et al., 1998; Ketcham et al., 2009; Stockli, 2005; Szymanski et al., 2016). In this study, zircon and apatite fission-track (FT) dating methods are used to constrain the ages and thermal history of samples from the GXR. The exhumation and cooling of the GXR and their relationship with the burial history of the adjacent SB are analyzed. The results will not only constrain the Mesozoic–Cenozoic tectono-thermal events in the GXR, but also provide further insights into tectonic evolution of NE China and its geodynamic setting, in particular the influence of the Paleo-Pacific subduction. 2 Geological setting 2.1 NE China NE China is located in the eastern part of the CAOB and has evolved from consecutive amalgamations of several microcontinental terranes or blocks since the late Cambrian (Wu et al., 2011). During the Paleozoic, the Erguna Block and Xing’an Terrane collided (~490 Ma) along the Tayuan–Xiguitu suture zone owing to subduction of the Paleo-Asian Ocean (Wu et al., 2011). The combined Erguna–Xing’an Terrane was sutured to the Songliao Terrane before the Permian (Nozaka and Liu, 2002; Wu et al., 2002; Zhou et al., 2004). Previous studies indicate that the Solonker–Xar Moron–Changchun suture zone between the Songliao and Liaoyuan Terranes may represent the final closure of the long-lived eastern Paleo-Asian Ocean (Chen et al., 2000; Wilde, 2015; Wu et al., 2011; Xiao et al., 2015). The Paleo-Asian Ocean closed by scissor-like motion from the west near the Tarim Craton to the east near Changchun, which was likely completed during the Late Permian to Triassic (Eizenhöfer et al., 2014; Shen et al., 2019; Wilde, 2015; Xiao et al., 2009). In the Mesozoic, NE China began to be influenced by the Paleo-Pacific subduction,

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which not only resulted in accretion of the Jiamusi Massif, Khanka Block, and Nadanhada and Sikhote-Alin Terranes in the eastern continental margin, but also affected inland areas such as the GXR and SB (Grebennikov et al., 2016; Jahn et al., 2015; Martynov et al., 2017; Wilde et al., 1999; Wu et al., 2007). The account of time between the end of the Paleo-Asian Ocean closure and the onset of tectonic activity associated with the Paleo-Pacific subduction is under debate (Wilde, 2015). The Mongol–Okhotsk suture belt developed during the closure of the Mongol–Okhotsk Ocean, which separated the Siberian Craton from the amalgamated Mongolia–North China Craton (NCC), and it played an important role in the tectonic evolution of NE China during the Mesozoic (Li et al., 2017b; Tang et al., 2016; Wang et al., 2015). The Mongol–Okhotsk oceanic plate was subducted not only northward beneath the Siberian Craton during the early Mesozoic, but also southward beneath the Erguna Massif (Tang et al., 2016; Wu et al., 2011). The Mongol–Okhotsk Ocean closed progressively from west to east in a scissor-like manner from the Early Jurassic to the Cretaceous (Şengör et al., 1993; Wang et al., 2015). Early Jurassic granitoids along the Mongol-Okhotsk belt are related to the closure of the Mongol–Okhotsk Ocean, whereas Late Jurassic granitoids in the GXR may be dominated by the Paleo-Pacific Plate subduction (Wang et al., 2015). Early Cretaceous granitoids in the Mongol–Okhotsk belt and adjacent areas were formed by post-orogenic extensional collapse of the Mongol–Okhotsk belt and back-arc extension related to the Paleo-Pacific subduction (Li et al., 2019; Tang et al., 2015). NE China is characterized by voluminous Mesozoic granitic rocks (Fig. 1c), of which the Late Triassic to Jurassic granitoids are distributed mainly in the east and north, and the Early Cretaceous granitoids are distributed in the west, for example, the GXR, the SB, and Xilinhot (Wang and Chen, 2015; Wu et al., 2011). In addition, sporadic Paleozoic granitoids are scattered around the

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regions of Tahe, Xing’an, Jiamusi, and so on. Geochemically, I- and A-type granitoids, according to the proposed criteria of (Chappell, 1999), are the most widespread rock type (Li et al., 2017a; Wu et al., 2003; Wu et al., 2002). 2.2 Great Xing’an Range The study area is located in the southern part of the GXR, NE China. The Xing’an Terrane comprises the GXR (also named Daxinganling or Da Hinggan Mountains) and the Hailar Basin (Fig. 1b). Tectonically, the GXR belongs to the Xing’an–Mongolia Orogenic Belt, which is the eastern part of the CAOB (Ho et al., 2013). The basement of the GXR consists mainly of Paleozoic island-arc related assemblages, including metamorphic volcano-sedimentary rocks, epipelagic limestones, clastic rocks and voluminous intrusive rocks (Ge et al., 2005; Wu et al., 2011). Over 75% of the GXR consists of exposed igneous rocks (Li et al., 2011), primarily Early Cretaceous granitoids, as well as some scattered Jurassic and Paleozoic granitoids (Wu et al., 2011). The crustal thickness under the GXR is approximately 37–40 km, which is significantly greater than that under the adjacent SB (33–35 km) (Xiong et al., 2015). 3 Sampling and methods 3.1 Sampling strategy and description Twelve individual samples, targeting apatite- and zircon-bearing granitoids, were collected from field outcrops of the GXR along two parallel NW-SE linear transects crossing the Xing’an Terrane. The locations of all the samples are plotted in Fig. 1c, and their GPS data are listed in Table 1. The crystallization ages of these samples are derived from published data (Table 1). The ages of most samples place them in the Early Cretaceous, and the other samples are from the Carboniferous, Permian, and Jurassic. 8

Representative photomicrographs of these samples are show in Fig. 2. Samples GXR01, GXR04, GXR05, GXR07, GXR10 and GXR11 are medium to fine grained monzonite in composition, display a typical granitic texture (Fig. 2), and are dominated by quartz (25–30%), K-feldspar (35– 45%), plagioclase (20–35%), biotite (2–4%), and accessory magnetite, zircon, apatite and titanite, with or without hornblende. Some alteration minerals are sericite and argillaceous. Samples GXR02 is rhyolite and displays porphyritic texture. The phenocrysts (~8–10%) mainly consist of K-feldspar, plagioclase and biotite. GXR03 and GXR12 are granophyre and display a typical porphyritic texture. The phenocrysts (~35%) mainly consist of quartz (8–10%), K-feldspar (10–20%), plagioclase (5–15%), minor hornblende (1–2%) and biotite (~1%), and accessory magnetite, zircon and titanite. The groundmass (~65%) is microcrystalline texture composed of alkali feldspar (35–45%), quartz (25– 30%), minor plagioclase and biotite. The K-feldspar and quartz show micrographic structure (Fig. 2). Sample GXR06 is dusty grey-red in color, displays a mylonitic texture and massive structure. The main mineral components include quartz (25–30%), K-feldspar (15–20%), plagioclase (~35%), chlorite (~10%) and minor epidote (3-4%). The protolith is monzonite, which is metamorphosed into altered granitic mylonite under the influence of late tectono-thermal metamorphism. Samples GXR08 and GXR09 are medium to fine grained syenogranite, display a granitic texture (Fig. 2), with main minerals of quartz (~30%), K-feldspar (~50%), plagioclase (~5–15%), minor biotite (3–4%), and accessory magnetite, zircon, apatite and titanite.

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In addition to the mylonitized monzonite (sample GXR06), the widespread alteration minerals, such as chlorite, sericite and epidote, indicate that all these samples have partially undergone alteration and deformation due to the late tectono-thermal events. 3.2 Fission-track thermochronology Zircon and apatite are common accessory minerals in many granitic rock suites of NE China (Gong et al., 2018; Tang et al., 2016). Zircon and apatite fission-track (ZFT and AFT, abbreviated) thermochronological systems are sensitive to paleo-geothermal changes caused by tectono-thermal events in lithospheric near-surface (Lisker et al., 2009; Song et al., 2018a; Stockli, 2005). The onset and rate of orogenic exhumation and post-orogenic erosional processes can be resolved by time-temperature (t-T) history reconstruction by the measured FT data (ZFT age, AFT age, Dpar value and confined track lengths) (Tian et al., 2012; Yuan et al., 2006; Zhang et al., 2016). Combining the ZFT and AFT approaches, which have the partial annealing zone (PAZ) of about 80–120 °C and 160–240 °C respectively (Gleadow et al., 1986; Ketcham et al., 1999; Yamada et al., 1995), allows for better resolution in thermal history reconstruction in Great Xing’an Range, NE China. 3.3 Laboratory processing The twelve collected field samples were crushed in order to extract zircon and apatite minerals using conventional magnetic and heavy-liquid separation approaches. Some samples do not yield sufficient zircon and apatite grains. Fission-track analysis were carried out using external detector method (Hurford and Green, 1983). Apatite grains were mounted in epoxy resin on glass slides and polished prior to being etched in 7% HNO3 for 40 s at 25℃, in order to reveal spontaneous fission-tracks (Yuan et al., 2006). Zircon grains were mounted on FEP Teflon wafers, polished

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with diamond paste, and then etched to reveal the spontaneous tracks in the eutectic (1:1) mixture of NaOH and KOH for about 22 h at 220 ℃ (Feng et al., 2017). Uranium-poor muscovite flakes were subsequently placed adjacent to the etched sample mounts before they were irradiated with thermal neutrons in the well-thermalized (Cd value for Au >100) 492 Swim-pool hot neutron reactor at the Beijing Institute of High Energy Physics, Chinese Academy of Sciences. After irradiation, the external muscovite flakes were etched in 40% HF at 25 ℃ for 20 min to reveal the induced fission tracks. Neutron flux was detected with CN2 and CN5 uranium dosimeter glasses for the zircon and apatite samples (Bellemans et al., 1995; Feng et al., 2017). Fission-track density, diameter of track etch pit parallel to the c-crystallographic axis (Dpar value) and track lengths (Gleadow et al., 1986), are counted and measured under 1000x magnification by an AUTOSCAN system from AUTOSCAN Systems Pty. Ltd., Australia. The central ages of the fission tracks were calculated using the Zeta calibration method recommended by the International Union of Geological Sciences (IUGS) (Galbraith and Laslett, 1993; Hurford, 1990). The chi-square (χ2) value was applied to evaluate the probability of all ages belonging to a single population (Galbraith, 1981; Galbraith and Laslett, 1993). A probability of <5% is evidence of overdispersion and will be indicated by the percentage dispersion about the central age. 4 Thermochronology and t–T modeling results 4.1 FT data A total of 18 FT ages (10 ZFT and 8 AFT) were obtained. The detailed results are shown in Table 2. Chi-square test (χ2) values of >5% indicate a single age population for most samples, and only four ZFT samples failed the χ2 test. The central ages of all the samples were calculated. The ZFT method yielded a group of central ages ranging from 80 ± 4 to 185 ± 10 Ma, with the oldest

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ZFT age found at the northernmost Cross River (GXR06/Zr), whereas the youngest age was measured in the most southeastern part of the Ulanhot area (GXR12/Zr), indicating a close correlation between the ages and sampling locations. The ZFT age of the rhyolite (sample GXR12/Zr) is 120 ± 8 Ma, which is consistent with the extrusive age (Table 1). The ZFT ages show an approximately positive correlation with their sampling altitudes (Fig. 3), indicating that these samples may be influenced by contemporaneous tectono-thermal events during the Jurassic to Early Cretaceous. The spectrum of the eight AFT central ages ranges from 55 ± 3 to 75 ± 5 Ma, with mean track lengths ranging from 13.2 ± 1.8 to 13.9 ± 2.2 μm. All the AFT samples passed the χ2 test, indicating that their ages are statistically geologically significant. The AFT ages show no clear correlation with the sample locations but do show an unusual negative correlation with elevation (Fig. 3), suggesting that the regional exhumation may be nonuniform and influenced by a different paleogeothermal field. Such a negative trend can appear for several reasons (Dörr et al., 2012). The changes in relief during exhumation may result in a negative age–elevation trend (Braun, 2002). This phenomenon is more common for thermo-chronometers with lower closure temperature because the thermal perturbation caused by surface topography decreases exponentially with depth (Braun, 2002). In addition, regional faults crossing the sampling area can also lead to such a negative trend. The measured AFT length distributions are not typical unimodal and/or bimodal distributions but show a mixed pattern, implying that the samples have undergone a complex multi-stages thermal history (Fig. 4). The key to understanding the mixed track length distributions in intrusive rocks is how and when those pre-existing FTs were partially annealed under the influence of the subsequent elevated paleo-geotherm. Gleadow et al. (1986) indicated that those rocks that

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monotonously cooled very rapidly would be referred to as an “undisturbed volcanic-type” length distribution. In addition, as the cooling history of a sample deviates from the monotonic pattern, the track length distribution becomes more complex. Therefore, we speculate that these samples collected from the GXR have been subsequently thermally disturbed near the partial annealing zone (PAZ). 4.2 Thermal history modeling The HeFty software of Ketcham (2005) was used to model the thermal history using the data on the AFT ages, FT length distributions, and Dpar values. Typically, a sample yielding more than thirty dated grains and approximately a hundred confined tracks is suitable for thermal history modeling (Table 2). The t–T paths of all the samples were calculated using the multi-kinetic model and the c-axis projected lengths (Ketcham et al., 2007). Forward modeling was preliminarily applied to test possible t–T paths, which were then refined by inverse modeling by the Monte Carlo search algorithm. The initial track lengths for modeling were based on the measured sample Dpar values. Published data were taken as the references for the sample formation ages (Table 1), and the time–temperature windows at 180–240 ℃ were constrained by the ZFT data (Fig. 5). Kuiper’s statistic, which equalizes the sensitivity between the median track length distribution and the tails, was used for the goodness of fit (GOF) of the length (good = 0.5, acceptable = 0.05), and the ending condition was 100 good paths. The modeling results of eight AFT samples are shown in Fig. 5. The envelope of good t–T paths of all the samples is characterized by a multistage cooling history, including two periods of relatively rapid cooling and one reheating interval (Fig. 5). The t–T paths appear flat or have a relatively gradual slope within the PAZ of zircon (~180–240 ℃). The first significant cooling process began early in the Late Cretaceous, with an average cooling 13

rate of 1.9 ℃/Myr at ca. 100–85 Ma and an accelerated cooling rate of 3.9 ℃/Myr from ca. 85 to 60 ± 2 Ma (Fig. 6a). The paleo-temperature decreased to ~60 ℃ (above the apatite PAZ) after this cooling event. Though the cooling extent of all the samples is consistent, the onset, timing and type of cooling through the PAZ of apatite differ (Fig. 6a). This long-term continuous cooling was interrupted by a reheating interval, causing the samples to re-enter the apatite PAZ of ~60–120 ℃. This reheating episode has a time span of approximately 10 Ma. Overall, the t–T paths show that this reheating resulted from a regional tectono-thermal event and is related to one geodynamic process. Thereafter, the other rapid cooling event occurred in the early Eocene (~50 ± 2 Ma) and continues to the present day. The average cooling amplitude and rate during this stage are 80 ℃ and 1.6 ℃/Myr, respectively (Fig. 6a). 4.3 Exhumation rate and thickness Thermochronology, along with an estimate of the geothermal gradient, can provide key constraints on the exhumation of rocks. The present-day geothermal gradient in the GXR is inferred to be ~35 ℃/km, and it increases southeastward to ~37 ℃/km in the adjacent SB (Hu et al., 2000; Li et al., 2011). The Earth’s surface temperature at the elevation and latitude of the study area is set to 5 ± 5 ℃. From the above assumptions and thermochronology analysis results, we infer that the field outcrop samples should have been buried at depths of ~5–6, ~2–3, and ~1 km early in the Late Cretaceous, in the Paleocene, and in the Early Neogene, respectively (Fig. 6a). The estimated burial depth may differ from the actual value because the thermal gradient was not constant during the Mesozoic–Cenozoic. The current elevation of the GXR ranges from several hundreds of meters to nearly two kilometers above sea level. Moreover, the widespread Lower Cretaceous continental deposits indicate that surface uplift was limited during the Early Cretaceous.

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The total unroofing thickness since the Late Cretaceous is therefore over ~3–4 km. The estimated exhumation rate can reach ~112 m/Myr during the Late Cretaceous, which is higher than that of the second cooling stage. 5 Discussion 5.1 Late Mesozoic magmatism and geodynamics The Mesozoic igneous rocks in NE China can be divided into two groups (Wu et al., 2011; Zhang et al., 2010). The Late Triassic to Jurassic magmatic rocks are distributed mainly in the Zhangguangcai Range, Lesser Xing’an Range (LXR), and Erguna Terrane, whereas the GXR and surrounding areas are characterized by widespread Early Cretaceous granitoids (Fig. 1c, Fig. 6b). The southern Solonker–Xar Moron suture zone, which developed during the Late Permian to Triassic (~250 Ma), represents the southern termination of the CAOB and final closure of the Paleo-Asian ocean (Wilde, 2015; Xiao et al., 2003). During the early Mesozoic, the orogenic uplift and contraction along the Solonker–Xar Moron suture zone are closely related to the collision between the NCC and the Siberian Craton, and subduction of the Mongol–Okhotsk Ocean (Wang et al., 2015; Xu et al., 2013). The subsequent post-orogenic tectonics and magmatism during the Jurassic to Early Cretaceous are considered to be influenced by the closure of the Mongol–Okhotsk Ocean (Ying et al., 2010), the onset of the Paleo-Pacific oceanic plate subduction (Guo et al., 2015; Liu et al., 2017), or both (Wang et al., 2015; Xu et al., 2013). Furthermore, the evolution of granitoids from calc-alkaline I-type granite to shoshonitic and high-K calc-alkaline transitional IA and/or A-type granite indicates a tectonic transition from lithospheric thickening to extensional thinning (Li et al., 2017a; Wang et al., 2015). The metamorphic core complexes, dolerite dykes, gold–molybdenum mineral deposits, rift basins, and extensional faults identified throughout the

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eastern CAOB (Fig. 6c) are representative products of extensional settings in the Early Cretaceous (Ji et al., 2019; Wu et al., 2005). Therefore, the Mesozoic granitoids, especially the Early Cretaceous (Fig. 1c, Fig. 6b) granitoids in the GXR and surrounding areas, are thought to derive from different geodynamic setting compared to the Paleozoic granitoids (Li et al., 2019; Ouyang et al., 2015). As mentioned above, the emplacement and distributions of the late Mesozoic magmatic rocks have been well studied using voluminous geochronological data (Wu et al., 2011). However, the deep geodynamics of the intensive Early Cretaceous magmatism in the GXR is still controversial. Using detailed analysis of multiple isotopic systems (e.g., Hf, O and Li isotopes), Li et al. (2017) proposed that several surviving ancient hydrous fragmented slabs from the subducted Paleo-Asian Ocean plate became unstable and released water into the upper lithosphere owing to the Early Cretaceous extension, resulting in water-fluxed partial melting and large-scale intracontinental magmatism. A previous analysis of the seismic tomography provided evidence for the presence of Jurassic slab remnants under Siberia, which subducted in the lower mantle when the Mongol– Okhotsk Ocean closed at least 150 Ma ago (Van der Voo et al., 1999). A key point of this model is the interpretation of the Early Cretaceous extension, including the time, type, and dynamic mechanism. 5.2 Thermal history and implications for geodynamic processes Using the zircon and apatite FT dating method, we reconstructed the thermal evolution history of the GXR since the Cretaceous. Tectono-thermal events experienced by the GXR, including uplift, exhumation, and deep magmatic activity, can be deciphered from the FT ages and t–T modeling results of this study. The Mesozoic–Cenozoic geological evolution history of NE Asia comprises alternating episodes of subduction and transform strike-slip movement of the oceanic 16

plate along the eastern continental margin of Eurasia (Engebretson et al., 1985; Grebennikov et al., 2016; Wilde, 2015). The response of tectono-thermal events related to tectonic regime conversion during this period can be determined. Therefore, detailed low-temperature thermochronology data and modeling results would provide key constraints on the tectonic process and its deep geodynamic setting. 5.2.1 Late Jurassic to Early Cretaceous The ZFT dating results indicate that the sampled granitoids from the GXR entered the zircon PAZ (180–240 ℃) from the Late Jurassic to Early Cretaceous, when localized Late Jurassic igneous rocks and voluminous Early Cretaceous granitoids were emplaced (Fig. 6). The ZFT age of 120 ± 8 Ma of sample GXR12/Zr (rhyolite) is consistent with its extrusive age. The ZFT ages show a youngling trend from the northernmost Cross River to the southeastern Ulanhot area, which is apparently related to closure of the Mongol–Okhotsk Ocean and the evolution of the collisional suture zone in the northeastern part of the CAOB during this period (Fig. 7). Yang et al. (2015) proposed that the brief but significant Mongol–Okhotsk collisional orogenic event occurred during the latest Jurassic to earliest Cretaceous, resulting in the formation of a giant fold-thrust belt in northern China and Mongolia, and uplift and erosion of the surrounding areas. This tectonic episode is consistent with the initial cooling period obtained from the t–T modeling of the GXR. In addition, it was also proposed that the subduction of the Paleo-Pacific plate was related to the Mesozoic–Cenozoic tectonic evolution of the GXR (Wang et al., 2006; Zhang et al., 2008), although the initial time and scenario of the Paleo-Pacific subduction are still controversial. In the eastern continental margin of NE Asia, the accretionary prisms, including the Sikhote-Alin area (Far East Russia), Nadanhada and Khanka, experienced multi-stage subduction or transform strikeslip movements of the Paleo-Pacific plate along the east continental margin of NE Asia 17

(Grebennikov et al., 2016; Martynov et al., 2017; Zhou et al., 2014). The early stage of the PaleoPacific subduction is thought to have commenced ca. 250 Ma ago (Liu et al., 2017), whereas the collision between the oceanic plate and eastern continental margin occurred mainly during the Jurassic–Early Cretaceous (Zhou et al., 2014). The tectonic accretion dominated by this convergence process was thus completed during this period. Moreover, the temporal-spatial distribution characteristics of magmatic rocks throughout NE Asia imply a possible relationship with the tectonic evolution of the Paleo-Pacific Ocean (Wu et al., 2005). In addition, previous studies have shown that the early Mesozoic magmatism in the Erguna Terrane was closely related to the subduction and closure of the Mongol–Okhotsk Ocean, but was not influenced by the circum-Pacific tectonic regime (Tang et al., 2016). Therefore, the Xing'an terrane may represent the possible western boundary of the influence of the Paleo-Pacific subduction. Thus, we prefer the viewpoint that the widespread Mesozoic igneous rocks in the GXR resulted mainly from closure of the Mongol–Okhotsk Ocean in the north and were subsequently influenced by the Paleo-Pacific plate subduction in the east, and that their transformations overlap in time (Fig. 7). In this scenario, the regional principal stress direction around the GXR changed from south-eastward to westward before the early stage of the Late Cretaceous (Enkin et al., 1992). 5.2.2 Late Cretaceous to Paleocene (~100–60 Ma) The thermochronology and t–T modeling results show that the first significant cooling event occurred from the early stage of the Late Cretaceous to the Paleocene (Fig. 6a). The cooling rate (~1.9 –3.9 ℃/Myr) and amplitude (~120 ℃), as well as the calculated maximum exhumation thickness (~3.5 km) during the Late Cretaceous to the Paleocene, are high, implying that the regional uplift of the GXR was relatively fast, and the orogenic activity was strong. This tectonic

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process occurred after closure of the Mongol–Okhotsk Ocean was complete (Fig. 6c) and may be related to the subsequent development of a collisional belt in the northwest. The more important geodynamic process during this period is the Paleo-Pacific subduction along the East Asian continental margin. A series of Mesozoic-Cenozoic petroliferous rifted sedimentary basins in East China, such as the SB, Bohai Bay Basin, Yellow Sea Basin, and East China Sea Basin, were all influenced by this geodynamic process (Pang et al., 2019). In NE China, the strong erosion of the GXR provides a large provenance input for the adjacent SB and Hailar Basin (Fig. 8). The rapid deposition and subsidence of the SB indicate that it entered the post-rift evolution stage during this period (Feng et al., 2010; Wang et al., 2016). The sedimentary facies are characterized mainly by large-scale foreland fluvial, alluvial, deltaic, and shallow lacustrine deposits over a vast area (Feng et al., 2010). Furthermore, a large amount of flood basalt (~200 m thick) erupted along the NE-SW axis of the SB at the Coniacian stage (Wang et al., 2016), which was associated with the rapid subsidence–burial history of the basin, but was significantly younger than the volcanic rocks in the GXR. This can be related to the asthenospheric upwelling coinciding with lithospheric thinning beneath the SB and dominated by the Paleo-Pacific subduction. Therefore, the evolution of the SB–GXR basin–mountain system implies a close spatial–temporal relationship between the tectonic denudation and burial history, and the western Pacific tectonic domain (Fig. 6, Fig. 8). The reliable thermal evolution history obtained in this study enables us to further decipher the influence of this subduction on the tectonic evolution of the GXR. The cooling rate ranges from an average of 1.9 ℃/Myr at ca. 100–85 Ma to 3.9 ℃/Myr at ca. (85–60) ± 2 Ma, showing an accelerating trend (Fig. 6a). During this time span (Cenomanian–Maastrichtian), the movement of the Izanagi Plate shifted from northwest-ward (100–85 Ma) to westward (85–74 Ma), leading to

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the initial frontal subduction of the Paleo-Pacific plate (Engebretson et al., 1985). The geodynamic setting of NE Asian changed from the transform continental margin in the late Albian to the active Andean-type during the Late Creataceous (Grebennikov et al., 2016). In addition, Yang (2013) concluded that the Okhotomorsk Block, which is currently below the Okhotsk Sea in NE Asia, moved northwest-ward with the subduction of the Izanagi Plate and collided with the East Asian continental margin during the Late Cretaceous. Interactions at plate boundaries may control the (crustal) stress field of intraplate regions and then affect the structural evolution. Thus, because of the consistency among these geological events, we have reasons to believe that the orogenesis, uplift, and exhumation in the GXR, and the rifting, deposition, and magmatism in the SB, as well as the accretion, metamorphism, and magmatism in the NE Asian continental margin are all directly or indirectly related to the Paleo-Pacific subduction. 5.2.3 Late Paleocene to Eocene (~60–50 Ma) A significant regional reheating episode during the Late Paleocene to Eocene (~10 Ma) was revealed by our modeling results (Fig. 5, Fig. 6a). Typical reasons for an increase in paleotemperature include reburial, an increase in the paleotemperature gradient, or both. However, there is no evidence that the GXR, as the main provenance input area of the surrounding Mesozoic– Cenozoic sedimentary basins (Fig. 8), experienced significant reburial and sedimentation during this period. Therefore, this reheating episode was likely caused by the change in the paleogeothermal field beneath the study area (Fig. 9). Previous studies have shown that the paleotemperature gradient and heat flow in the SB can reach ~42–48 ℃/km and ~95–107 mW/m2 during the Late Cretaceous to Early Paleogene, respectively, which are both far higher than the current values (Hu et al., 2000; Ren et al., 2011). The paleo-geothermal field in the GXR can refer

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to the SB, because the collision and suture of the two terranes was complete before the Permian (Wu et al., 2011). This geothermal warming event in the GXR is relatively transient but exists objectively. However, what is the deep geodynamic process of this regional reheating event during this period? Magma intrusion is an important factor in the increase in paleotemperature in East Asia (Chang et al., 2011; Pang et al., 2017a). As discussed above, the tectonic evolution of NE Asia had already been dominated by the subduction of the Paleo-Pacific plate since the Late Cretaceous. After a long period of subduction, the subsiding slab may break off and form steeply inclined structures of shear extension, which provide ascending pathways for injection of asthenosphere material (Li et al., 2017, Zhang et al., 2010, Grebennikov et al., 2016 and references therein). In addition, other ancient subsided slabs from closed paleo-oceans (that is, the Late Permian Paleo-Asian Ocean, Mesozoic Mongol–Okhotsk Ocean, and Mudanjiang Ocean), which might interact with each other under NE China (Fig. 7), would transport additional water to the upper asthenosphere (Windley et al., 2011). This injection of oceanic asthenosphere material and the induced igneous activity have important effects on the thermal structure of the lithosphere surface. If we adopt the above geodynamic model to interpret this reheating episode, the other key issue is to determine why it began. First, dominated by the change in the direction of the Paleo-Pacific subduction and movement, the NE Asian continental margin changed from active Andean-type (Cenomanian–Maastrichtian) to transform-type (Paleocene–Eocene) tectonism (Engebretson et al., 1985; Grebennikov et al., 2016). The transformation time of this tectonic process is consistent with this reheating episode, suggesting a direct or indirect causal relationship between them. Second, another important tectonic event during this period is the India–Asia collision. This event generally occurred from the Paleocene to the Eocene (~60–55 Ma) and significantly affected the

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structural pattern of the East Asian continent during the Cenozoic (G. Donaldson et al., 2013; Meng et al., 2018). The far-field effects of this collisional event might reactivate those ancient subsided water-bearing slabs below NE China and break the balance of the deep geodynamic system. The induced asthenospheric upwelling and/or subsequent igneous activity may have changed the thermal structure of the upper lithosphere surface, resulting in the increase in the paleotemperature of the GXR. This unique geothermal rebound also appeared in the adjacent SB. It occurred during the postrift stage of basin evolution at ~85–70 Ma (Cheng et al., 2018; Song et al., 2018b), which is earlier than that of the GXR. The flux of the deep heat source derived from the younger subducted slabs of the Paleo-Pacific Ocean, which was transmitted through the lithospheric necking zones, is considered to be a reasonable explanation for the geothermal reheating event (Song et al., 2018b). This issue should be studied in detail because it may reveal important information on the deep geodynamic process and evolution. 5.2.4 Eocene to Present (~50–0 Ma) The Cenozoic cooling path from our modeling results is prolonged, continuous and monotonic (Fig. 5). This cooling event appears in most Mesozoic–Cenozoic orogenic belts in east Asia, and the dominant factor is the Paleo-Pacific subduction (Li et al., 2011; Pang et al., 2019; Wang et al., 2018; Wu et al., 2016). These significant exhumation and cooling phenomena are probably responses to the impact of the Indian subcontinent from the southwest (Cheng et al., 2018; Xiang et al., 2007). Furthermore, if the cooling or exhumation event of the GXR is linked with the tectonic subsidence–burial evolution history of the adjacent SB, we can infer the following. (1) The Xing’an Terrane and SB have a unified tectonic background during this period (Du et al., 2019; Wu et al., 2011). (2) The uplift and exhumation of the GXR are coeval with the filling of the 22

Cretaceous continental facies basin, which formed a vast basin–mountain system, and the depocenter of the SB approached the western GXR (Wang et al., 2016). Moreover, lowtemperature thermochronological data from the SB reveal two or more uplift events related to tectonic inversion since the Eocene, indicating that this exhumation event is regional and widespread (Cheng et al., 2018; Fang et al., 2005; Xiang et al., 2007). (3) No large-scale late superimposed faults developed other than some inversion structures (Feng et al., 2010). The upper crustal structure and topographic relief of the GXR were almost stable, and the exhumation may be inherited (Fig. 9). If this is the case, the reheating episode before this cooling event was also accompanied by regional uplift and exhumation, and represented a more dramatic change in the paleo-geothermal field of the study area. 6 Conclusions 1. Zircon FT dating of samples from the GXR yielded a group of central ages ranging from 80 ± 4 to 185 ± 10 Ma, whereas the apatite FT ages ranged from 55 ± 3 to 75 ± 5 Ma, indicating that the samples recorded multiple Mesozoic–Cenozoic tectono-thermal events in this region. 2. The envelope of modeled t–T paths reveals two relatively rapid cooling events at ~100–60 Ma and ~50–0 Ma, respectively, and one distinctive reheating episode at ~60–50 Ma. The tectonothermal evolution during the Late Jurassic to Early Cretaceous was influenced mainly by closure of the Mongol–Okhotsk Ocean in the north, and was subsequently influenced by the Paleo-Pacific plate subduction in the east. The subsequent exhumation and cooling events are all dominated or indirectly influenced by the Paleo-Pacific subduction, and there is a temporal overlap between the end of the Paleo-Asian Ocean closure and the onset of tectonic activity associated with the PaleoPacific subduction.

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3. The reheating episode during the Late Paleocene to Eocene controlled by the change of the lithosphere thermal structure is related to the heat flux derived from the asthenosphere upwelling and igneous activities, which may be induced by the change of direction of the Paleo-Pacific subduction, or the far-field effects of the India–Asia collision. Acknowledgments We are grateful to Editor Diane Chung, and the anonymous referees for their constructive comments which greatly improved this paper. We are grateful to Professor Ge Wenchun for enthusiastic guidance on field sampling. This study is supported by Shandong Provincial Natural Science Foundation, China (Grant No. ZR2018BD026), National Natural Science Foundation of China (Grant No. 41806057, 41776081), China Postdoctoral Science Foundation (Grant No. 2017M620290), National Marine Geology Project (DD20160147), China Geological Survey Project (DD20190365), the Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology (MGQNLM201902), and the Research Team Fund of Shandong University of Science and Technology (2015TDJH101). References Bellemans, F., De Corte, F., Van Den Haute, P., 1995. Composition of srm and cn u-doped glasses: Significance for their use as thermal neutron fluence monitors in fission track dating. Radiation Measurements 24, 153-160. Braun, J., 2002. Quantifying the effect of recent relief changes on age–elevation relationships. Earth and Planetary Science Letters 200, 331-343. Chang, X.C., Han, Z.Z., Li, Z.X., Yang, S.P., Chen, Q.C., 2011. Formation Mechanisms of Paleogene Igneous Rock Plays in Huimin Sag, Eastern China. Energy Exploration & Exploitation 29, 455-478. Chappell, B.W., 1999. Aluminium saturation in I- and S-type granites and the characterization of fractionated haplogranites. Lithos 46, 535-551. Chen, B., Jahn, B.M., Wilde, S., Xu, B., 2000. Two contrasting paleozoic magmatic belts in northern Inner Mongolia, China: petrogenesis and tectonic implications. Tectonophysics 328, 157-182. Cheng, Y.H., Wang, S.Y., Li, Y., Ao, C., Li, Y.F., Li, J.G., Li, H.L., Zhang, T.F., 2018. Late Cretaceous–Cenozoic thermochronology in the southern Songliao Basin, NE China: New insights from apatite and zircon fission track analysis. Journal of Asian Earth Sciences 160, 95-106. Dörr, N., Lisker, F., Clift, P.D., Carter, A., Gee, D.G., Tebenkov, A.M., Spiegel, C., 2012. Late Mesozoic–Cenozoic exhumation history of northern Svalbard and its regional significance: Constraints from apatite fission track analysis. Tectonophysics 514-517, 81-92.

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Figures: Fig. 1. (a) Schematic map showing the Central Asian Orogenic Belt (CAOB), the main tectonic units and the location of the study area (modified from Zhou et al., 2014). (b) Geological sketch map of NE China and the regional tectonic boundaries (modified from Wu et al., 2011; Wilde, 2015), and the sampling locations. EB: Erguna block; XB: Xing’an block; SXB: Songliao–Xilinhot block; JB: Jiamusi block; NT: Nadanhada terrane; KB: Khanka block; NCC: North China craton. (c) Distribution of the Phanerozoic granitoids in NE China (modified from Wu et al., 2011). Fig. 2. Representative photomicrographs showing the main mineral compositions and microscopic texture. Qtz: quartz, Pl: plagioclase, Kfs: K-feldspar, Bt: biotite, Hbl: Hornblende. Fig. 3. (a) Samples show a positive trend of ZFT ages with increasing elevation, while AFT ages show a negative correlation with sample altitudes, and (b) AFT ages vs. mean track lengths (MTLs). Fig. 4. Apatite fission-track length distributions with lengths (μm) plotted against frequency for samples from the Great Xing’an Range. Fig. 5. Inverse thermal history modelling results together with track length distributions of samples from the Great Xing’an Range. The time-temperature (t–T) paths were computed using the Hefty software (Ketcham, 2005) based on measured fission-track data. The present-day Earth surface temperature is set at 5 ± 5 ℃. The ZFT data were used to create the time-temperature window to constrain the peak paleo-temperatures reached by AFT samples. The merit values for “acceptable” and “good” fit t–T paths are set at 0.05 and 0.5, respectively. The goodness of fit (GOF) of the best statistical fit path is shown. Fig. 6. (a) Sketch of time-temperature (t–T) paths with cooling rates integrated from ZFT, AFT ages and modeling results. The mean path between 180 ℃ and 240 ℃ is mainly constrained by the ZFT ages from this study, while the path from 180 – 120 ℃ to 120 – 0 ℃ are based on the modeling results in Fig. 5. The burial depth (right Y-axis) is calculated from 35 ℃/km of assumed geothermal gradient (Hu et al., 2000). Ve:

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exhumation rate; Vt: cooling rate. (b) Compilation of age data of granitoids and volcanic rocks from the GXR (modified after Yang et al., 2015, Li et al., 2017 and references therein). (c) Sketch timeline of tectonic events for the eastern CAOB and surrounding areas, the main references are listed in the graph. Fig. 7. Schematic model of paleo-geodynamic reconstruction of the Great Xing’an Range and adjacent areas. Fig. 8. (a) Cross-section through the GXR and SB, the depositional sequences are based on borehole-constrained seismic interpretation. Location is shown in Fig. c (A-B-C). (b) Integrated stratigraphic sequences column of SB revealed by wells, such as SK-1n, SK-1s and SK-2 from International Continental Drilling Program - ICDP (based on Wang and Chen, 2015, and references therein). (c) Structural outline map of the SB–GXR basinmountain system and surrounding areas, showing the potential input directions of deposition during the Late Cretaceous (modified from Wang et al., 2016). Fig. 9. Schematic thermal structure model of Great Xing’an Range, accounting for the reheating event at ~60– 50 Ma.

Tables: Table 1 Sampling position, lithology and ages of field samples from central Great Xing’an Range, NE China. Table 2 Fission-track dating data of the Great Xing’an Range using the Zeta external detector method (Hurford and Green, 1983). Central age is weighted for different precisions of individual crystals (Galbraith and Laslett, 1993). Zircon ages calculated with Zeta (ζ) = 94.5 ± 3.2 (yr cm2/tr) and apatite ages calculated with Zeta (ζ) = 410 ± 17.6 (yr cm2/tr). Track densities (ρ) are as measured and given in × 105·cm-2. N – number of counted tracks,

ρs (ρi, ρd) – spontaneous (induced, dosimeter) track densities, P(χ2) – chi-square probability, MTL – mean track length.

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Sample

Longitude

Latitude

Elevation

Lithology

Method

Age (Ma)

References

GXR01

122°46.317′

48°0.200′

332 m

Monzonite

LA-ICPMS

301 ± 3

Wu et al., 2011

GXR02

122°20.838′

48°12.893′

546 m

rhyolite

ZFT

120 ± 8

—

GXR03

122°18.076′

48°20.359′

457 m

Granophyre

LA-ICPMS

142 ± 3

Wu et al., 2011

GXR04

121°42.334′

48°47.656′

957 m

Monzonite

LA-ICPMS

309 ± 4

Wu et al., 2011

GXR05

121°39.494′

48°49.376′

967 m

Monzonite

LA-ICPMS

267 ± 3

Wu et al., 2011

GXR06

121°04.520′

49°04.270′

709 m

Mylonitized monzonite

LA-ICPMS

249 ± 2

Wu et al., 2011

GXR07

119°45.861′

47°18.939′

861 m

Monzonite

LA-ICPMS

135.1 ± 0.4

Xie et al., 2011

GXR08

120°02.529′

47°06.526′

1328 m

Syenogranite

LA-ICPMS

129 ± 1

Wu et al., 2011

GXR09

120°50.356′

46°42.337′

698 m

Syenogranite

LA-ICPMS

135 ± 2

Wu et al., 2011

GXR10

121°15.419′

46°36.182′

512 m

Monzonite

LA-ICPMS

126 ±2

Ge et al., 2005

GXR11

121°24.180′

46°06.539′

432 m

Monzonite

LA-ICPMS

182 ± 3

Ge et al., 2005

GXR12

122°08.402′

46°08.188′

348 m

Granophyre

LA-ICPMS

138 ± 3

Wu et al., 2011

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Sample /mineral

Grain/n

ρs(Ns)

ρi(Ni)

ρd(Nd)

P(χ2) (%)

Central Age (± 1σ/Ma)

Pooled Age (± 1σ/Ma)

MTL (± 1σ/μm)/N

GXR01/Zr

3

90.285 (213)

48.321 (114)

13.362 (6696)

60.0

117±14

117±14

-

GXR02/Zr

8

188.81 (928)

99.084 (487)

13.482 (6696)

77.9

120±8

120±8

-

GXR03/Zr

33

126.001 (5264)

83.035 (3469)

13.641 (6696)

0.1

94±5

97±4

-

GXR04/Zr

4

181.71 (518)

87.347 (249)

13.8 (6696)

54.2

134±11

134±11

-

GXR05/Zr

2

118.005 (174)

51.543 (76)

13.959 (6696)

30.4

149±21

149±21

-

GXR06/Zr

35

101.28 (2479)

36.075 (883)

14.118 (6696)

60.1

185±10

185±10

-

GXR07/Zr

30

118.053 (4549)

79.826 (3076)

14.277 (6696)

0.0

99±5

99±4

-

GXR08/Zr

18

144.982 (2038)

84.158 (1183)

14.436 (6696)

5.0

119±7

117±6

-

GXR09/Zr

35

131.076 (3466)

73.517 (1944)

12.584 (6696)

0.0

101±6

105±5

-

GXR12/Zr

35

94.617 (3339)

74.526 (2630)

13.561 (6696)

0.6

80±4

81±4

-

GXR01/Ap

38

1.016 (270)

3.425 (910)

10.769 (6313)

75.2

65±5

65±5

13.9±2.2 (124)

GXR03/Ap

35

2.138 (787)

5.813 (2140)

10.006 (6313)

18.1

75±5

75±5

13.5±2.3 (103)

GXR04/Ap

35

5.109 (1240)

17.556 (4261)

9.243 (6313)

7.0

55±3

55±3

13.2±1.8 (104)

GXR05/Ap

35

2.451 (887)

6.08 (2200)

8.671 (6313)

41.0

71±4

71±4

13.9±1.6 (104)

GXR06/Ap

37

1.822 (371)

4.429 (902)

8.099 (6313)

98.0

68±5

68±5

13.3±2.1 (100)

GXR07/Ap

35

2.506 (471)

6.273 (1179)

7.336 (6313)

6.8

62±5

60±5

13.2±1.8 (106)

GXR09/Ap

35

2.707 (479)

6.437 (1139)

6.764 (6313)

99.7

58±4

58±4

13.9±1.6 (104)

GXR10/Ap

35

2.139 (613)

6.554 (1878)

10.959 (6313)

78.3

73±5

73±5

13.4±1.9 (114)

33

Graphical abstract

34

Highlights

  

Two cooling events occurred at ~100–60 Ma and ~50–0 Ma, and one reheating episode at ~60–50 Ma in the Great Xing’an Range. Tectono-thermal evolution was closely related to the closure of the Mongol-Okhotsk Ocean and the Paleo-Pacific subduction. There is a temporal overlap between the end of the Paleo-Asian Ocean closure and the onset of the Paleo-Pacific subduction.

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Declaration of interests ☒ The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

☐The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:

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