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Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Late triassic to late Jurassic sedimentary basins of the central Yanshan fold–thrust belt
  5. Deposition, provenance and unroofing record in the Xingshikou Formation
  6. Zircon analyses from the Xingshikou Formation
  7. Discussion
  8. Conclusions
  9. Acknowledgements
  10. References
  11. Supporting Information

Early Mesozoic Basins in the Yanshan Fold–Thrust Belt (YFTB), located along the northern margin of the North China Craton (NCC), record significant intraplate deformation of unknown age. In this article, we present evidence for the rapid exhumation of high-grade basement rocks along the northern margin of the NCC in the Early Mesozoic. U–Pb geochronology of detrital zircons constrains the maximum depositional ages of syntectonic sedimentary units that formed during the unroofing of basement rocks and plutons in the Xiabancheng Basin. In the Early Mesozoic, the Xiabancheng Basin recorded a dramatic transformation in depositional environments, related to a significant change in the regional tectonic setting. In this study, the tectonic evolution of the YFTB is established from paleocurrent data and U–Pb zircon ages of sandstone and granitic gravels of the Xingshikou Formation, Xiabancheng Basin. The paleocurrent direction of meandering fluvial facies in the Triassic Liujiagou and Ermaying Formations are from east to west. In contrast, the overlying Xingshikou Formation consists of alluvial fan facies with paleocurrent directions from north-northwest to south-southeast. The lower and middle segments of the Xingshikou Formation record rapid exhumation of basement rocks along the northern margin of the NCC. U-Pb ages of detrital zircons within the Xingshikou Formation are characterized by three major U–Pb age groups: 2.2–2.5 Ga, 1.7–1.8 Ga and 193–356 Ma. From 193 Ma to 356 Ma, a subsidiary peak occurs at 198 ± 5 Ma, constraining the sedimentation age of the Xingshikou Formation to the Early Jurassic. Zircon from the Wangtufang pluton in the northern portion of the Xiabancheng Basin yields U–Pb ages of 191 ± 1 Ma and 207 ± 1 Ma. Within error, these crystallization ages are identical to detrital zircon ages of 206 ± 1 Ma and 206 ± 2 Ma obtained for granitic gravel clasts in the Xingshikou Formation. Thus, the Wangtufang pluton and surrounding basement rocks must have experienced rapid uplift and exhumation during the Early Jurassic. The onset of exhumation along the northern margin of the NCC occurred at ca. 198–180 Ma.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Late triassic to late Jurassic sedimentary basins of the central Yanshan fold–thrust belt
  5. Deposition, provenance and unroofing record in the Xingshikou Formation
  6. Zircon analyses from the Xingshikou Formation
  7. Discussion
  8. Conclusions
  9. Acknowledgements
  10. References
  11. Supporting Information

U–Pb age spectra of detrital zircons from clastic sedimentary rocks provide important constraints on the evaluation of potential source regions (Yang et al., 2006). They also reflect exhumation of the source region, supplying important information on orogenic uplift and exhumation (Hendrix et al., 1996). Detrital zircons are both common and extremely stable (Yan et al., 2003).

Syntectonic conglomerates in fold–thrust belts on the timing of thrusting and unroofing of source terranes (Cope et al., 2007). Allochthonous clasts can serve to link syntectonic strata to their source regions, and to constrain their uplift and erosional history (Graham et al., 1986; DeCelles et al., 1987; Jones et al., 2004). Precise constraints on the deposition age of syntectonic conglomerates in fold–thrust belts yield detailed information on the development and paleogeography of the belt. Such results may be further supported by stratigraphic correlations, paleocurrent data, facies analysis, structural data and clast provenance (DeCelles, 1994; Hoy & Ridgway, 1997; Yang et al., 2006). The Yanshan tectonic belt is located near the northern margin of the North China Craton (NCC) (Fig. 1). After the NCC collided with the Mongolian arc terranes in the Late Paleozoic, the northern edge of the NCC evolved from a plate margin to an intraplate environment in terms of tectonic setting (Davis et al., 2001). Over the past century, many geological and tectonic studies have been conducted on the Mesozoic–Cenozoic rocks in the region. The Yanshan Fold–Thrust Belt (YFTB) experienced at least two major episodes of compressional deformation: during the Triassic to Early Jurassic and the Late Jurassic to Early Cretaceous (Cope et al., 2007; Liu et al., 2007). However, the nature and timing of exhumation of basement rocks remains controversial (Zhao, 1990; Wang, 1996; Davis et al., 2001; Zhang, 2004; Zhang et al., 2004, 2007a, b, c) because of the obscuring effects of extensional tectonic overprinting during the Cretaceous and voluminous magmatism in the Jurassic and Cretaceous.

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Figure 1. Geological sketch map of the northern margin of the NCC (modified after Zhang et al., 2006; index figure modified after Davis et al., 2001). WH, Western Hills of Beijing; X., Xiabancheng Basin.

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Davis et al. (2001) stated that uplift and exhumation in northernmost China occurred prior to ca. 180 Ma, based on the ages of volcanic rocks that unconformably overlie crystalline basement in northern Yanshan. On the basis of detrital zircons from the Western Hills of Beijing, Yang et al. (2006) concluded that syntectonic conglomerate (Liu et al., 2004) was deposited in the Early Jurassic. The timing of the onset of rapid basement exhumation along the northern margin of the NCC remains unclear.

In this article, we present a model for the evolution of the Xiabancheng Basin, as inferred from depositional environments and from evidence gathered to document rapid basement exhumation in the Early Mesozoic. Using detrital zircon U–Pb ages, we have determined the maximum depositional ages and provenance of syntectonic deposits in the Xiabancheng Basin, which formed as a consequence of the unroofing of the northern NCC (Davis et al., 2001).

Geological setting

The northern margin of the NCC, located southeast of the Central Asian Orogenic Belt, is divided into two E–W trending tectonic units by the Pingquan–Gubeikou Fault (also called the Shangyi–Gubeikou–Pingquan Fault; Hebei Bureau of Geology & Mineral Resources (HBGMR), 1989): the Inner Mongolia Paleo-Uplift (IMPU; HBGMR, 1989) to the north and the YFTB to the south (HBGMR, 1989; Davis et al., 2001) (Fig. 1). The IMPU is characterized by extensive Archean–Proterozoic high-grade basement rocks that are unconformably overlain by Jurassic–Cretaceous volcanic and sedimentary rocks. The entire tectonic province was exhumed during the Late Carboniferous to Early Jurassic (Zhao, 1990; Zhang et al., 2007a).

Archean IMPU basement rocks consist predominantly of ca. 2.5 Ga syntectonic granites and a variety of supracrustal rocks, which experienced greenschist to granulite facies regional metamorphism and polyphase deformation at ca. 2.5 Ga (Jahn et al., 1984; Kröner et al., 1998). Paleoproterozoic (1.9–2.1 Ga) rocks unconformably overlie Neoarchean basement rocks (Zhao et al., 2001, 2002). The main deformation and metamorphism of Paleoproterozoic basement occurred at ca. 1.85 Ga, and is considered to indicate cratonization of the NCC (Zhao et al., 2002). The YFTB consists mainly of Paleoproterozoic basement, Meso–Neoproterozoic rocks, Cambrian to Ordovician marine clastic and carbonate platformal sediments, Middle Carboniferous to Triassic fluvial and deltaic sediments and Jurassic to Cretaceous (and younger) volcanic and sedimentary rocks. The maximum thickness of the Meso–Neoproterozoic and early Paleozoic strata is ca. 11.5 km (HBGMR, 1989), but these units are almost entirely absent in the IMPU (Fig. 1). Thick sequences of predominantly clastic sedimentary rocks were deposited across the YFTB during 1.40–1.85 Ga, forming the Changcheng Series (Li et al., 1985; Kusky & Li, 2003). Late Paleozoic to Early Mesozoic magmatism was widespread across the YFTB, with reported U–Pb zircon ages of 200–400 Ma (Davis et al., 2001; Zhang, 2004; Zhang et al., 2004, 2007a, b, c, 2010). The Early Mesozoic Wangtufang pluton, located along the northern portion of the Pingquan–Gubeikou Fault, is the most well-exposed example of this magmatism, and consists mainly of granite and diorite. The pluton lacks any record of ductile deformation. Zircon from granite sampled from the northeast and southern portions of the Wangtufang pluton yields U–Pb ages of 191 ± 1 Ma and 207 ± 1 Ma respectively (Liu, 2006a; Figs 2 and 3).

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Figure 2. Geological sketch map of the eastern segment of the YFTB (modified after Zhang et al., 2006, 2009; HBGMR (Hebei Bureau of Geology & Mineral Resources), 1976). U–Pb zircon data from: Davis et al. (2001); Zhao et al. (2004); Zhang (2004); Liu (2006a).

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Figure 3. Geological sketch map of the Pingquan–Wangtufang region, northern Hebei province (the figure is modified after HBGMR (Hebei Bureau of Geology & Mineral Resources), 1976; and using data of the present study; see Fig. 2). U–Pb zircon or whole rock K–Ar or whole rock Rb-Sr isochron data from: Davis et al. (2001); Zhao et al. (2004); Liu (2006a); HBG (Hebei Bureau of Geology), 1996; Wang et al. (1994).

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The YFBT is structurally complex because of at least two significant episodes of Mesozoic shortening; structural features and basins associated with these two events are cut by Mesozoic plutons and mid-Cretaceous extensional structures (Cope et al., 2007). The first major compressional episode affecting the YFBT occurred in the Late Triassic to Early Jurassic (Zhao, 1990; Davis et al., 2001); its demise is dated at 180 Ma on the basis of widespread Jurassic-age volcanic rocks, which unconformably overlie Archean basement and extend nearly as far as the Mongolian border (Davis et al., 2001; Fig. 1). Late Triassic coarse-grained fluvial and alluvial strata, occurring south of the IMPU, are syntectonic deposits related to unroofing and erosion of the IMPU (Davis et al., 2001). The second major compressional episode that affected the YFBT, referred to as the ‘Yanshan Movement’ or ‘Yanshanian’ event (Wong, 1927), has been widely accepted by Chinese geologists to define Jurassic to Early Cretaceous orogenic activity throughout China. The event is constrained by the absolute age of volcanic strata in the YFBT, at ca. 135–160Ma (Zhao et al., 2004).

Late triassic to late Jurassic sedimentary basins of the central Yanshan fold–thrust belt

  1. Top of page
  2. Abstract
  3. Introduction
  4. Late triassic to late Jurassic sedimentary basins of the central Yanshan fold–thrust belt
  5. Deposition, provenance and unroofing record in the Xingshikou Formation
  6. Zircon analyses from the Xingshikou Formation
  7. Discussion
  8. Conclusions
  9. Acknowledgements
  10. References
  11. Supporting Information

Late Triassic are unconformably overlain by Late Jurassic strata in the YFTB, including volcanic and volcaniclastic deposits of the Tiaojishan Formation (HBGMR, 1989; Liu et al., 2006b), that yield U–Pb zircon ages of 157–160 Ma (Zhao et al., 2004; Liu et al., 2006b; Hu et al., 2007; Fig. 4).

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Figure 4. Late Triassic–Jurassic stratigraphy of the central YFTB, showing the units discussed in the text. As pointed out by Davis (2005), these stratigraphic assignments represent lithostratigraphic correlations, not chronostratigraphic ones, and thus all Mesozoic boundaries shown in this figure are highly diachronous throughout the YFTB. The Early Triassic Liujiagou Formation unconformably overlies (paraconformity) Ordovician strata in the Shanggu area; however, it is in conformable contact with Permian strata at Yingzi area in the Xiabancheng Basin (Fig. 2).

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Early to Middle Triassic strata in the Xiabancheng Basin include the Middle Triassic Ermaying Formation and the Early Triassic Liujiagou Formation. The Early to Middle Triassic Shuangquan Formation is restricted to the Western Hills of Beijing (HBGMR, 1989; Liu et al., 2005). The Late Triassic to Late Jurassic strata in the Western Hills of Beijing and in the Xiabancheng Basin are dominated by the Late Triassic Xingshikou Formation, the Early–Middle Jurassic Nandaling Formation, the Middle Jurassic Xiahuayuan Formation and the Late Jurassic Jiulongshan Formation (HBGMR, 1989; Liu et al., 2005; Zhao et al., 2006; Liu, 2006a; Fig. 4). The basins are distributed along the southern portion of the Pingquan–Gubeikou Fault, defining a flexural basin (Liu et al., 2004).

The Xingshikou Formation in the Shanggu area of the Xiabancheng Basin unconformably overlies the Middle Triassic Ermaying Formation (Liu et al., 2004, 2005). In contrast, in the Western Hills of Beijing, the Xingshikou Formation unconformably overlies the Early–Middle Triassic Shuangquan Formation (Fig. 4).

Late Triassic Xingshikou Formation

The Late Triassic Xingshikou Formation is found mainly within the Xiabancheng Basin and Western Hills of Beijing, with few occurrences in the Chaoyang area in West Liaoning (HBGMR (Hebei Bureau of Geology & Mineral Resources), 1989; LBGMR (Liaoning Bureau of Geology & Mineral Resources), 1989; Fig. 1). The Xingshikou Formation consists of conglomerates with sandstone lenses. And is about 590–690 m thick in the Shanggu area within the Xiabancheng Basin (Liu et al., 2005). Gravels are rounded to subrounded, generally with diameters of 10–25 cm (range, 5–40 cm). Overall, gravel size coarsens upward along the entire section with a weak imbrication. Paleocurrent indicators from imbricated gravels indicate southward flow (Figs 5 and 6). The Xingshikou conglomerate is interpreted as an alluvial fan deposit (Liu et al., 2005).

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Figure 5. Measured stratigraphic section of the Xingshikou Formation in the Shanggu area, Xiabancheng Basin, showing paleocurrent data, clast provenance data and interpreted source intervals in the hanging wall of the Pingquan–Gubeikou thrust.

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Figure 6. Geological sketch map of the Shanggu area, Xiabancheng County, northern Hebei province (HBGMR (Hebei Bureau of Geology & Mineral Resources), 1976; HBG (Hebei Bureau of Geology), 1996; authors’ data, see Fig. 2).

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Late Triassic sedimentary rocks of the Xingshikou Formation in the YFTB are highly deformed alluvial and fluvial strata that crop out in an E–W trending belt extending to the northeast from the Shanggu area in the Xiabancheng Basin (Figs 2 and 3). The Xingshikou Formation in this region has been divided into three segments as part of regional 1 : 50 000 mapping (HBG (Hebei Bureau of Geology), 1996).

The lower and middle segments of the formation are thick-bedded cobble to boulder conglomerate with gravel contents of 50–75%. The lower segment consists predominantly of quartzite and carbonate clasts, with a small number of volcanic clasts. The middle segment consists mainly of gneiss and granitic-gneiss gravel. The gravel from both segments is well rounded. The conglomerate contains 20–40% sandstone and mudstone matrix infill, with 5–10% calcite cement. The largely massive conglomerate includes lenses of granular to coarse-grained sandstone and fine-grained sandstone. The combined thickness of the lower and middle segments of the Xingshikou Formation ranges from 140 to 400 m (HBG, 1996; Liu et al., 2005). The upper segment, which contains coal layers, consists of meandering channel, lacustrine and delta deposits, with a total thickness is 50–150 m (HBG, 1996; Liu et al., 2005).

In the Western Hills of Beijing, Xingshikou Formation consists of granular conglomerate, with some sandstone intervals, and has an overall thickness of 15–20 m. Gravel clasts are slightly rounded, and the conglomerate is massive or with cross-laminations. The Xingshikou Formation in the Western Hills of Beijing is interpreted as meandering channel gravel deposits (Liu et al., 2004) that represent the depositional response to thrusting-related uplift in the IMPU source area (Liu et al., 2004).

Middle Jurassic Nandaling and Xiahuayuan Formations

The Middle Jurassic Nandaling Formation consists of basic volcanic lava flows and associated sedimentary rocks. The Nandaling Formation is about 234 m thick in the Shanggu area in the Xiabancheng Basin (Liu et al., 2005). The Xiahuayuan Formation in the YFTB immediately overlies basic volcanic rocks of the Nandaling Formation that yield an 40Ar–39Ar biotite age of 180 ± 2 Ma (Davis et al., 2001). In the Shanggu area, Xiahuayuan Formation contains coal measures and consists predominantly of meandering channel, lacustrine and delta deposits with a total thickness of 237 m (Liu et al., 2005).

In the Western Hills of Beijing, the Xiahuayuan Formation (also called the Yaopo Formation) within the Western Hills of Beijing is 620 m thick and is underlain by basic volcanic rocks of the Nandaling Formation, which yield a minimum U–Pb zircon age of 174 ± 8 Ma (Zhao et al., 2006; Fig. 4). This formation constitutes a depositional cycle from lacustrine to fluvial facies (Liu et al., 2004).

Late Jurassic Jiulongshan Formation

The Jiulongshan Formation occurs within the Xiabancheng Basin and Western Hills of Beijing. In the Shanggu area in the Xiabancheng Basin, it consists of coarse sandstone, conglomerate, red shale and silty shale. Its thickness in the Xiabancheng Basin is 206 m, and it is interpreted be an alluvial fan deposit (Liu et al., 2005).

In the Western Hills of Beijing, the Jiulongshan Formation consists of grey lithic sandstones, fine tuffaceous sandstones, siltstones and several conglomerate intervals, which are interpreted to be fan delta deposits (Liu et al., 2004). Regional correlations show that within the Xiabancheng Basin, deposits of the Jiulongshan Formation are coarser-grained than within the Western Hills of Beijing. Therefore, different depositional systems developed in each of the basins.

Deposition, provenance and unroofing record in the Xingshikou Formation

  1. Top of page
  2. Abstract
  3. Introduction
  4. Late triassic to late Jurassic sedimentary basins of the central Yanshan fold–thrust belt
  5. Deposition, provenance and unroofing record in the Xingshikou Formation
  6. Zircon analyses from the Xingshikou Formation
  7. Discussion
  8. Conclusions
  9. Acknowledgements
  10. References
  11. Supporting Information

Methods

The composition of basin gravels and sandstones is an important indicator of the uplift and erosional history of basin-margin mountains (Hendrix et al., 1996; Hendrix, 2000). Sedimentary rocks of the Xingshikou Formation in the Xiabancheng Basin are dominated by gravels that were investigated in the field. At each site, nearly every clast in an area of 2 m2 was identified, typically more than 80–100 clasts. Results are shown in Fig. 5. Clasts were counted at six equally spaced intervals across the 540 m thick footwall conglomeratic section. A plot of composition vs. vertical position in the measured section is shown in Fig. 5.

Paleocurrent data have been used to determine the direction of clast provenance (Liu et al., 2004; Cope et al., 2007). The paleocurrent orientation in the Late Triassic Xingshikou Formation and Middle Triassic Ermaying Formation was determined from the largest flat gravel surfaces with imbricate structures, in gravelly sandstones. The paleocurrent orientation of the Early Triassic Liujiagou Formation was determined from tabular cross-bedding laminae and other sedimentary structures in sandstone. At least 20 orientations were measured at each site. The paleocurrent data show that Xingshikou Formation gravels were transported from a northern source. However, clasts from both the Middle Triassic Ermaying Formation and Early Triassic Liujiagou Formation were transported from an eastern source (Fig. 6).

Temporal changes in gravel components

Xingshikou Formation conglomerates preserve a clear record of the erosional unroofing of the hanging wall of the Pingquan–Gubeikou thrust (Fig. 5). The hanging wall sequence is well suited for gravel provenance studies because it includes a variety of distinctive lithologies that appear at known stratigraphic levels (Fig. 7a–d). The hanging wall of the Pingquan-Gubeikou thrust consists, from the top to base, of (1) Mesoproterozoic carbonate rocks of the Jixian Group, which are buff-coloured thinly bedded to stromatolitic dolomite containing variable amounts of chert; (2) Mesoproterozoic carbonate rocks of the Changcheng Group, mainly dolomite with thickly interbedded quartzite; and (3) strongly metamorphosed Archean–Paleoproterozoic basement rocks and plutonic rocks (HBGMR, 1989).

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Figure 7. Photographs of structural relationships and clast lithologies in the Xiabancheng Basin. (a) conglomerates with sandstone lenses, lower segment of Xingshikou Formation. (b) Cherty dolomite clast, typical of lithologies of the Mesoproterozoic Jixian Group. (c) Cherty quartzite clast, typical of lithologies of the Mesoproterozoic Changcheng Group. Imbricate structure of the middle segment of the Xingshikou Formation. (d) Gneiss and granite clasts sourced from Archean–Paleoproterozoic high-grade basement rocks.

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Figure 5 shows that the lower segment of the Xingshikou Formation consists mainly of quartzite and carbonate gravels (15–50% and 50–85% respectively). The percentage of clasts unequivocally derived from the Mesoproterozoic Jixian Group (stromatolitic dolomite and chert) decreases upsection, whereas clasts derived from the Mesoproterozoic Changcheng Group (dolomite and quartzite) increase, reflecting progressively deeper erosion of the hanging wall.

The middle segment of the Xingshikou Formation consists mainly of quartzite and gneiss clasts (15–30% and 50–65% respectively). Minor clast components in the middle segment include granite, volcanic and carbonate clasts (1–5%, 10–15% and 1–40% respectively). Conglomerate clasts at the base of the middle segment are predominantly dolomite and quartzite derived from the Mesoproterozoic Changcheng Group cover sequence. The percentage of clasts unequivocally derived from the Mesoproterozoic Changcheng Group (dolomite and quartzite) decreases upsection, whereas clasts derived from Archean–Paleoproterozoic rocks (gneiss and granite) increases. These trends represent the progressive unroofing of the Mesoproterozoic Changcheng Group and Archean–Paleoproterozoic rocks, as granite began to be eroded (Liu et al., 2007; Fig. 5). Paleocurrent indicators are directed to the south, reflecting the progressively deeper erosion of hanging wall rocks of the Pingquan–Gubeikou Fault (Fig. 5).

Zircon analyses from the Xingshikou Formation

  1. Top of page
  2. Abstract
  3. Introduction
  4. Late triassic to late Jurassic sedimentary basins of the central Yanshan fold–thrust belt
  5. Deposition, provenance and unroofing record in the Xingshikou Formation
  6. Zircon analyses from the Xingshikou Formation
  7. Discussion
  8. Conclusions
  9. Acknowledgements
  10. References
  11. Supporting Information

Sample preparation and imaging

Zircons were separated using conventional crushing and separation techniques and were then handpicked under a binocular microscope. They were mounted on epoxy resin and polished to expose the cores of the grains for photomicrographs, cathodoluminescence (CL) and LA–ICP–MS U–Pb analyses. Zircons were imaged using the GATAN Mono CL3 attached to the FEI Quanta 400 scanning electron microscope in Northwest University to characterize internal textures and choose potential target sites for U–Pb dating. CL images of representative zircon grains are shown in Fig. 8.

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Figure 8. Representative cathodoluminescence (CL) images of zircons. Circles are zircon LA–ICP–MS U–Pb dating spots.

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LA–ICP–MS U–Pb analyses

LA–ICP–MS U–Pb dating was performed on an excimer (193 nm wavelength) LA–ICP–MS in Northwest University and China University of Geosciences (Wuhan) following the method described by Yuan et al. (2004) and Liu et al. (2010). The LA-ICP–MS used was an Agilent 7500a. The GeoLas 2005 laser-ablation system was used for the laser-ablation experiments. Sites for dating were selected on the basis of CL and photomicrograph images. The spots used were 30–32 μm in diameter. Common Pb corrections were made using the method described by Andersen (2002). U, Th and Pb concentrations were calibrated using 29Si as an internal standard and NIST SRM 610 as the reference standard. Isotopic ratios were calculated using GLITTER 4.0 (Macquarie University, New South Wales, Australia) and ICPMSDataCal 5.0 (Liu et al., 2010), and were then corrected for both instrumental mass bias and depth-dependent elemental and isotopic fractionation using Harvard zircon 91500 as an external standard. Concordia diagrams and weighted mean ages were produced using the program ISOPLOT/Ex 3.23 (Ludwig, 2003). Detailed analytical methods are presented in Supplementary Data Repository Appendix A.

Analytical results

A sample of coarse sandstone (xbc35) between gravels at the bottom of the lower member of the Xingshikou Formation was collected near the Shanggu area (40°47′55.1″N, 118°22′58.2″E; Fig. 5) for U–Pb analyses of zircons (n = 120). Grains ranged in size from 50 to 250 μm and were equate to elongate, and generally subrounded. Some grains were metamict (radiation damaged), consistent with older ages (Fig. 8a). Three major zircon populations corresponded to three significant age groups: 2247–2503 Ma, 1719–1875 Ma and 193–302 Ma, with principal peaks at 2504 ± 5 Ma, 1763 ± 7 Ma and 252 ± 2 Ma respectively (Supporting Information Table SDR1; Figs 9 and 10). The four youngest grains give 206Pb/238U ages of 193 to 211 Ma, with a weighted mean age at 198 ± 5 Ma (Fig. 9).

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Figure 9. LA–ICP–MS U–Pb detrital zircon concordia diagrams for sandstone sample xbc35, from the base of the Xingshikou Formation.

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Figure 10. U–Pb detrital zircon age probability plot for sample xbc35 from the base of the Xingshikou Formation in the Xiabancheng Basin. Above, probability distribution diagram and histogram (20 m.y. bins; Ludwing, 2001) of U–Pb ages, total sample size of 101 grains (discordance < 20%), with main peaks at 2503 ± 6 Ma, 1763 ± 7 Ma and 252 ± 2 Ma respectively.

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Thirty different gravels samples (from xbc19 to xbc48) of granite and granitic gneiss from the middle segment of the Xingshikou Formation were collected near the Shanggu area (Fig. 5). Only six zircons from each sample were dated. The 30 samples contain three age populations: 2433–2509 Ma, 1778–1875 Ma and 203–356 Ma, with principal peaks at 2494 ± 11 Ma, 1798 ± 14 Ma and 269 ± 3 Ma respectively (Fig. 11; Supporting Information Table SDR2). In the 203–356 Ma population, six grains from two granite gravels samples (xbc20, xbc21) yielded 206Pb/238U ages of 203–208 Ma. Subsequently, we carried out additional analyses on these two samples. Their weighted average ages are 206 ± 1 Ma (2σ; n = 12; MSWD = 1.9) and 206 ± 2 Ma (2σ; n = 16; MSWD = 1.8) respectively (Fig. 12; Supporting Information Table SDR3).

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Figure 11. U–Pb zircon age probability plot for thirty different gravels samples of granite and granitic gneiss from the middle segment of the Xingshikou Formation (see Fig. 5). Above, probability distribution diagram and histogram (20 m.y. bins; Ludwing, 2001) of U–Pb ages, total sample size of 180 grains. Six zircons from each sample were dated (discordance < 20%), with main peaks at 2494 ± 11 Ma, 1798 ± 14 Ma and 269 ± 3 Ma respectively.

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Figure 12. U–Pb concordia diagram for zircon from samples xbc20 and xbc21 of the Xingshikou Formation.

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Discussion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Late triassic to late Jurassic sedimentary basins of the central Yanshan fold–thrust belt
  5. Deposition, provenance and unroofing record in the Xingshikou Formation
  6. Zircon analyses from the Xingshikou Formation
  7. Discussion
  8. Conclusions
  9. Acknowledgements
  10. References
  11. Supporting Information

Depositional age of the Xingshikou Formation

Previous studies have suggested that sedimentary rocks of the Xingshikou Formation in the YFTB belong to the Late Triassic (HBGMR, 1976, 1989, 1996. Recently, Yang et al. (2006) systematically dated detrital zircon from the Xingshikou Formation in the Western Hills of Beijing. Their results confirm that the Xingshikou Formation is no older than Early Jurassic. Our detrital zircon analyses suggest that the Xingshikou Formation is younger than 198 ± 5 Ma. The most recent International Stratigraphic Chart (Gradstein et al., 2004) shows the Jurassic–Triassic boundary at 199.6 ± 0.6 Ma. Therefore, the Xingshikou Formation was deposited in the Early Jurassic.

Uplift and exhumation of basement rocks along the northern margin of the North China Craton in the Early Jurassic

In the Triassic, fluvial deposits began to accumulate in the Xiabancheng Basin, which at that time trended east–west (Liu et al., 2005; Fig. 13a). Early in the formation of the Xingshikou units, paleocurrents and sediment provenance underwent a marked change (Figs 5 and 6). Conglomerate clasts in the Xingshikou Formation provide evidence for thrust-related uplift and unroofing of Mesoproterozoic to Archean–Paleoproterozoic basement north of the Pingquan–Gubeikou Fault (Liu et al., 2007; Fig. 13b). The distribution of conglomerate in the Western Hills of Beijing is also a consequence of the thrust-related uplift of basin margins (Liu et al., 2004). The basins were distributed along the southern Pingquan–Gubeikou Fault, defining a flexural basin (Liu et al., 2004). The characteristics of the Xingshikou Formation suggest that basement rocks along the northern margin of the NCC were rapidly denuded during the Xingshikou period. In the early Middle Jurassic, basalt and basaltic andesites were erupted. Finger-like basalts were deposited over the Xiabancheng area, their propagation controlled by the topography and geomorphology of the Xingshikou period (Xu et al., 2006; Fig. 13c). During deposition of the Middle Jurassic Xiahuayuan Formation, an alluvial plain developed on the Nandaling Formation basalts, evolving into a fluvial–lacustrine system. Syn-depositional tectonism was weak; denudation and deposition processes functioned by truncating highlands and filling lowlands (Liu et al., 2004; Fig. 13d). Early in the Late Jurassic, northward thrusting was initiated along the Chengdexian Fault (CDXF) at the southern edge of the Xiabancheng Basin (Xu et al., 2006), dissecting the basin (Liu, 2006a; Xu et al., 2006; Fig. 13e). The evolution of the Xiabancheng Basin culminated in the Jiulongshan period (Liu, 2006a).

image

Figure 13. Schematic model of the development of the Xiabancheng Basin. See the text for details.

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As discussed above, detrital zircon extracted from sandstone, granite and granitic-gneiss gravels in the Xingshikou Formation gives three age populations (2.2–2.5 Ga, 1.7–1.8 Ga and 193–356 Ma; Figs 10 and 11) that represent three major tectonomagmatic events in the evolution of the IMPU (Jahn et al., 1984; Kröner et al., 1998; Zhao et al., 2001, 2002; Yang et al., 2006; Zhang et al., 2007a, b, c, 2010).

Tectonic deformation of the YFTB, the Early Mesozoic, has received much attention in recent years (Davis et al., 2001; Zhang et al., 2007a, b, c, 2010). Numerous Late Paleozoic–Mesozoic tectonic deformation zones and magmatic centres developed along the northern margin of the NCC (Zhang, 2004; Zhang et al., 2004, 2007c), which suggests that this intraplate belt of Mesozoic deformation in the Yanshan area was superimposed on an older, Late Paleozoic plate margin (Davis et al., 2001).

Gneissic textures are commonly developed in Late Paleozoic intrusive rocks at the northern margin of the NCC (Zhang, 2004), but clasts within granitic gravels in the Xingshikou Formation have retained their original igneous textures. The Early Mesozoic Wangtufang pluton is the largest exposure of igneous rocks north of the Pingquan–Gubeikou Fault. The pluton shows no sign of ductile deformation. U–Pb ages of zircon from medium-grained granite sampled from the northeast of the Wangtufang pluton and fine-grained granite from the south yield ages of 191 ± 1 Ma and 207 ± 1 Ma respectively (Liu, 2006a; Figs 2-4). The latter crystallization age of 207 ± 1 Ma is within error of the ages from the two youngest granite clasts sampled from the Xingshikou Formation, dated at 206 ± 1 Ma and 206 ± 2 Ma. The 191 ± 1 Ma age of medium-grained Wangtufang granite is the subsidiary peak of 198 ± 5 Ma for detrital zircon in the Xingshikou Formation. The Wangtufang pluton yields a whole rock K–Ar isochron age of 175 ± 10 Ma (HBG, 1996). Wang et al. (1994) obtained a whole rock Rb–Sr isochron age of 198 ± 10 Ma for this pluton. These dating results indicate that the cooling ages of the Wangtufang pluton are close to its crystallization age. It can be inferred that during the Early Jurassic, the Wangtufang pluton cooled and was unroofed rapidly. The subsidiary Xingshikou detrital zircon peak (198 ± 5 Ma) and weighted average ages of the youngest Xingshikou granite gravels (206 ± 1 Ma and 206 ± 2 Ma) are consistent with the timing of emplacement of the Wangtufang pluton. This provides further evidence that rapid exhumation occurred along the northern margin of the YFTB during deposition of the Xingshikou Formation. Rapid exhumation was facilitated by southward thrusting upon the Pingquan–Gubeikou Fault, leading to the deposition of Xingshikou Formation gravels. Davis et al. (2001) considered that exhumation in the YFTB occurred prior to ca. 180 Ma. On the basis of this study and considering previous work (e.g. Davis et al., 2001), rapid exhumation of basement rocks along the northern margin of the NCC occurred during the earliest Jurassic (180–198 Ma).

Conclusions

  1. Top of page
  2. Abstract
  3. Introduction
  4. Late triassic to late Jurassic sedimentary basins of the central Yanshan fold–thrust belt
  5. Deposition, provenance and unroofing record in the Xingshikou Formation
  6. Zircon analyses from the Xingshikou Formation
  7. Discussion
  8. Conclusions
  9. Acknowledgements
  10. References
  11. Supporting Information

Analyses of provenance, paleocurrents and detrital zircon of the Xingshikou Formation document a dramatic transformation in North China during the Early Mesozoic. Triassic deposits underlying the Xingshikou Formation formed in an east–west-flowing fluvial system. The Early Jurassic Xingshikou Formation comprises alluvial fan deposits that flowed from north-northwest to south-southeast. The lower and middle members of the Xingshikou Formation record exhumation of basement rocks along the northern margin of the NCC.

U–Pb ages of detrital zircons within the Xingshikou Formation are divided into three major age groups: 2.2–2.5 Ga, 1.7–1.8 Ga and 193–356 Ma, with a subsidiary peak at 198 ± 5 Ma. This result indicates that the Xingshikou Formation is younger than 198 ± 5 Ma and was deposited in the Early Jurassic. The Wangtufang pluton yields ages of 191 ± 1 Ma and 207 ± 1 Ma, within error of the youngest detrital zircon and granitic gravel U–Pb ages obtained from the Xingshikou Formation. It seems reasonable that the Wangtufang pluton and surrounding basement units experienced rapid uplift and exhumation during the Early Jurassic. The rapid exhumation of basement rocks along the northern margin of the NCC was initiated at around 198 Ma. This suggests that the Wangtufang pluton and high-grade basement rocks along the northern margin of the NCC experienced rapid exhumation during the deposition of the Xingshikou Formation. Thus, strong intraplate deformation in the YFBT occurred between 198 and 180 Ma.

Acknowledgements

  1. Top of page
  2. Abstract
  3. Introduction
  4. Late triassic to late Jurassic sedimentary basins of the central Yanshan fold–thrust belt
  5. Deposition, provenance and unroofing record in the Xingshikou Formation
  6. Zircon analyses from the Xingshikou Formation
  7. Discussion
  8. Conclusions
  9. Acknowledgements
  10. References
  11. Supporting Information

We thank G. A. Davis and T. D. Cope for their insightful reviews of earlier versions of the manuscript. This research was financially supported by the ‘Deep Exploration Technology and Experimentation’ Program of China (SinoProbe-08-01-03) and the National Natural Science Foundation of China (No. 40132020).

References

  1. Top of page
  2. Abstract
  3. Introduction
  4. Late triassic to late Jurassic sedimentary basins of the central Yanshan fold–thrust belt
  5. Deposition, provenance and unroofing record in the Xingshikou Formation
  6. Zircon analyses from the Xingshikou Formation
  7. Discussion
  8. Conclusions
  9. Acknowledgements
  10. References
  11. Supporting Information
  • Andersen, T. (2002) Correction of common lead in U–Pb analyses that do not report 204Pb. Chem. Geol., 192, 5979.
  • Cope, T.D. , Shultz, M.R. & Graham, S.A. (2007) Detrital record of Mesozoic shortening in theYanshan belt, NE China: testing structural interpretations with basin analysis. Basin Res., 19, 253272.
  • Davis, G.A. (2005) The late Jurassic'Tuchengzi/Houcheng'Formation of the Yanshan fold-thrust belt: an analysis. Earth Sci. Front., 12, 331345.
  • Davis, G.A. , Zheng, Y.D. & Wang, C. (2001) Mesozoic tectonic evolution of the Yanshan fold and thrust belt, with emphasis on Hebei and Liaoning provinces, northern China. Geol. Soc. Am. Mem., 194, 171197.
  • DeCelles, P.G. (1994) Late Cretaceous-Paleocene synorogenic sedimentation and kinematic history of the Sevier thrust belt, Northeast Utah and Southwest Wyoming. Geol. Soc. Am. Bull., 106, 3256.
  • DeCelles, P.G. , Tolson, R.B. , Graham, S.A. , Smith, G.A. , Ingersoll, R.V. , White, J. , Schmidt, C.J. , Rice, R. , Moxon, I. , Lemke, L. , Handschy, J.W. , Follo, M.F. , Edwards, D.P. , Cavazza, W. , Caldwell, M. & Bargar, E. (1987) Laramide thrust-generated alluvial-fan sedimentation, Sphinx Conglomerate, southwestern Montana. AAPG Bull., 71, 135155.
  • Gradstein, F.M. , Ogg, J.G. & Smith, A.G. (2004) A new geologic time scale with special reference to Precambrian and Neogene. Episodes, 272, 83100.
  • Graham, S.A. , Tolson, R.B. , DeCelles, P.G. , Ingersoll, R.V. , Bargar, E. , Caldwell, M. , Cavazza, W. , Edwards, D.P. , Follo, W.F. , Handschy, J.W. , Lemke, L. , Moxon, I. , Rice, R. , Smith, G.A. , White, J. & Homewood, P. (1986) Provenance modeling as a technique for analysing source terrane evolution and controls on foreland sedimentation. In: Foreland Basins (Ed. by Allen P.A. & Homewood P. ) Spec. Pub. Int. Ass. Sediment., 8, 425436.
  • HBG (Hebei Bureau of Geology). (1996) Scale 1 : 50000 Geological map of Shanggu sheet and regional geological survey report (in Chinese).
  • HBGMR (Hebei Bureau of Geology and Mineral Resources). (1976) Scale 1 : 200000. Geological map of Pingquan sheet and its explanation 85-101 (in Chinese).
  • HBGMR (Hebei Bureau of Geology and Mineral Resources). (1989) Regional Geology of Hebei Province, Beijing and Tianjin Municipality, Geological Publishing House, Beijing, pp. 182191 (in Chinese).
  • HBGMR (Hebei Bureau of Geology and Mineral Resources). (1996) Lithostratigraphy of Hebei Province, China University of Geosciences Publishing House, Beijing, pp. 6073 (in Chinese).
  • Hendrix, M.S. (2000) Evolution of Mesozoic sandstone compositions, southern Junggar, northern Tarim and western Turpan basins, northwest China: a detriatal record of the ancestral Tian Shan. J. Sed. Res., 70, 520532.
  • Hendrix, M.S. , Graham, S.A. & Amory, J.Y. (1996) Noyon Uul (King Mountain) Syncline, southern Mongolia: early mesozoic sedimentary record of the tectonic amalgamation of central Asia. Geol. Soc. Am. Bull., 108, 12561274.
  • Hoy, R.G. & Ridgway, K.D. (1997) Structural and sedimentological development of footwall growth synclines along an intraforeland uplift, east central Bighorn Mountains, Wyoming. Geol. Soc. Am. Bull., 109, 915935.
  • Hu, J.M. , Liu, X.W. & Yang, Z.Q. (2007) Geochronological constrains for the early mesozoic tectonic deformation of Yanshan intraplate orogen in northeastern China. Acta Petrologica Sinica, 23(3): 605616 (in Chinese with English abstract).
  • Jahn, B.M. , Vidal, P. & Kröner, A. (1984) Multi-chronometric ages and origin of Archean tonalitic gneisses in Finnish Lapland: a case for long crustal residence time. Contrib. Mineral. Petrol., 86, 398408.
  • Jones, M.A. , Heller, P.L. , Roca, E. , Garcés, M. & Cabrera, L. (2004) Time lag of syntectonic sedimentation across an alluvial basin: theory and example from the Ebro basin, Spain. Basin Res., 16, 489506.
  • Kröner, A. , Cui, W.Y. , Wang, C.Q. & Nemchin, A.A. (1998) Single zircon ages from high-grade rocks of the Jianping Complex, Liaoning Province, NE China. Asian Earth Sci., 16, 519532.
  • Kusky, T.M. & Li, J.H. (2003) Paleoproterozoic tectonic evolution of the North China Craton. Asian Earth Sci., 22, 2340.
  • LBGMR (Liaoning Bureau of Geology and Mineral Resources). (1989) Regional Geology of Liaoning Province, Geological Publishing House, Beijing, 851 (in Chinese).
  • Li, S. , Lin, Z. & Zhang, X.Q. (1985) The report on the age of Changzhougou and Chuanlinggou Formations of Changcheng system in Yanshan geology. Precambrian Res., 2, 129134.
  • Liu, J. (2006a) Yanshanian tectonic evolution of the Chengde basin and the adjacent area in the eastern segment of the Yanshan fold–thrust belt. Dissertation for the degree of doctor of Chinese Academy of Geological Sciences, 177 (in Chinese).
  • Liu, S.F. , Li, Z. & Zhang, J.F. (2004) Mesozoic basin evolution and tectonic mechanism in Yanshan, China. Sci. China D, 47(Supp. II), 2438.
  • Liu, X.W. , Hu, J.M. , Zhao, Y. , Wu, H. & Zhang, T.K. (2005) Stratigraphic division and correlation of the early- middle Jurassic in northern Hebei, China. Geol. Bull. China, 24(9), 872878 (in Chinese with English abstract).
  • Liu, J. , Zhao, Y. & Liu, X.M. (2006b) Age of the Tiaojishan Formation volcanics in the Chengde Basin, northern Hebei Province. Acta Petrologica Sinica, 22 (11), 26172630.
  • Liu, S.F. , Zhang, J.F. , Hong, S.Y. & Ritts, B.D. (2007) Early Mesozoic basin development and its response to thrusting in the Yanshan fold and thrust belt, China. Int. Geol. Rev., 49 (11), 10251049.
  • Liu, Y.S. , Gao, S. , Hu, Z.C. , Gao, C.G. , Zong, K.Q. & Wang, D.B. , (2010) Continental and oceanic crust recycling-induced melt-peridotite interactions in the Trans-North China Orogen: U-Pb dating, Hf isotopes and trace elements in zircons of mantle xenoliths. J. Petrol., 51, 537571.
  • Ludwig, K.R. (2001) SQUID 1.02: A user's manual. Berkeley Geochronology Center, Special Publication 2, 19 p.
  • Ludwig, K.R. (2003) User's Manual for Isoplot 3.00. A Geochronological Toolkit for Microsoft Excel. Berkeley Geochronology Center, Special Publication No. 4a, Berkeley, California, 70.
  • Wang, Y. (1996) Tectonic Evolutional Processes of Inner Mongolia-Yanshan Orogenic Belt in Eastern China During the Late of Late Paleozoic-Mesozoic. Geological Publishing House, Beijing (in Chinese with English abstract).
  • Wang, J.L. , Li, B.Z. & Zhou, D.X. (1994) Geologic Feature and its Mineralogenetic Relation of Neutral-to-acid Magma Body, Hebei Province, China. Geological Publishing House, Beijing (in Chinese).
  • Wong, W.H. (1927) The mesozoic orogenic movement in eastern China. Geol. Soc. Chin. Bull., 8, 83344.
  • Xu, G. , Zhao, Y. & Gao, R. (2006) Mesozoic basin deformation of Yanshan fold-thrust belt recordes of the intraplate deformation process: a case study of Xiabanchen, Chende-Shangbancheng and Beitai Basins. Acta Geoscientica Sinica, 27(1), 112 (in Chinese with English abstract).
  • Yan, Y. , Lin, G. & Li, Z.A. (2003) Provenance tracing of sediments by means of synthetic study of shape, composition and chronology of zircon. Geotectonica et Metallogenia, 27(2), 184190 (in Chinese with English abstract).
  • Yang, J.H. , Wu, F.Y. & Shao, J.A. (2006) Constraints on the timing of uplift of the Yanshan fold and thrust belt, North China. Earth Planet. Sci. Lett., 246, 336352.
  • Yuan, H.L. , Gao, S. , Liu, X.M. , Li, H.M. , Günther, D. & Wu, F.Y. (2004) Accurate U-Pb age and trace element determinations of zircon by laser ablation inductively coupled plasma mass spectrometry. Geostand. Geoanal. Res., 28, 353370.
  • Zhang, S.H. (2004) The late paleozoic early mesozoic tectonomagmatic belts in the eastern segment of the inner mongolian paleo-uplift in the Yanshan tectonic belt and their geological significance. Dissertation for the degree of doctor of Chinese Academy of Geological Sciences, pp. 1160 (in Chinese with English abstract).
  • Zhang, S.H. , Zhao, Y. & Song, B. (2004) The late paleozoic gneissic granodiorite pluton in early pre-cambrian highgrade metamorphic terrains near Longhua county in northern Hebei province, North China: result from zircon SHRIMP U-Pb dating and its tectonic implications. Acta Petrologica Sinica, 20(3), 621626 (in Chinese with English abstract).
  • Zhang, S.H. , Zhao, Y. & Song, B. (2006) Hornblende thermobarometry of the Carboniferous granitoids from the Inner Mongolia Paleo-uplift: implications for the tectonic evolution of the northern margin of North China block. Mineral. Petrol., 87, 123141.
  • Zhang, S.H. , Zhao, Y. , Song, B. & Liu, D.Y. (2007a) Petrogenesis of the middle Devonian Gushan diorite pluton on the northern margin of the North China Craton and its tectonic implications. Geol. Mag., 144, 553568.
  • Zhang, S.H. , Liu, S.W. , Zhao, Y. , Yang, J.H. , Song, B. & Liu, X.M. (2007b) The 1.75-1.68 Ga anorthosite–mangerite–alkali granitoid–rapakivi granite suite from the northern North China Craton: magmatism related to a Paleoproterozoic orogen. Precambrian Res., 155, 287312.
  • Zhang, S.H. , Zhao, Y. , Song, B. , Yang, Z.Y. , Hu, J.M. & Wu, H. (2007c) Carboniferous granitic plutons from the northern margin of the North China Craton: implications for a late paleozoic active continental margin. J. Geol. Soc. London, 164, 64516463.
  • Zhang, S.H. , Zhao, Y. , Song, B. , Hu, J.M. , Liu, S.W. , Yang, Y.H. , Chen, F.K. , Liu, X.M. & Liu, J. (2009) Contrasting late carboniferous and late permian–middle triassic intrusive suites from the northern margin of the North China craton: geochronology, petrogenesis, and tectonic implications. GSA Bull., 121, 181200.
  • Zhang, S.H. , Zhao, Y. , Liu, J.M. , Hu, J.M. , Song, B. , Liu, J. & Wu, H. , (2010) Geochronology, geochemistry and tectonic setting of the late paleozoic-early mesozoic magmatism in the northern margin of the North China block: a preliminary review. Acta Petrologica et Mineralogica, 29(6): 824842(in Chinese with English abstract).
  • Zhao, Y. (1990) The mesozoic orogenics and tectonic evolution of the Yanshan area. Geol. Rev., 36(1), 113 (in Chinese with English abstract).
  • Zhao, G.C. , Wilde, S.A. , Cawood, P.A. , Sun, M. & Lu, L.Z. (2001) Archean blocks and their boundaries in the North China Craton: lithological, geochemical, structural and P-T path constraints. Precambrian Res., 107, 4573.
  • Zhao, G.C. , Cawood, P.A. & Wilde, S.A. (2002) Review of global 2.1-1.8 Ga orogens: implications for a pre-Rodinia supercontinent. Earth-Sci. Rev., 59, 126162.
  • Zhao, Y. , Zhang, S. H. , Xu, G. , Yang, Z. Y. & Hu, J. M. (2004) The Jurassic major tectonic events of the Yanshanian intraplate deformation belt. Geol. Bull. China, 23(9–10): 854863 (in Chinese with English abstract).
  • Zhao, Y. , Song, B. & Zhang, S.H. (2006) Geochronology of the inherited zircon from Jurassic Nandaling Basalt of the western Hills of Beijing, North China: its implications. Earth Sci. Front., 13(2), 183190 (in Chinese with English abstract).

Supporting Information

  1. Top of page
  2. Abstract
  3. Introduction
  4. Late triassic to late Jurassic sedimentary basins of the central Yanshan fold–thrust belt
  5. Deposition, provenance and unroofing record in the Xingshikou Formation
  6. Zircon analyses from the Xingshikou Formation
  7. Discussion
  8. Conclusions
  9. Acknowledgements
  10. References
  11. Supporting Information
FilenameFormatSizeDescription
bre538-sup-0001-AppendixA.docxWord document12KSupplementary Data Repository Appendix A : Analytical methods
bre538-sup-0002-TableS1.docWord document412KTable SDR1. Summary of LA-ICP-MS U-Pb zircon results for sample xbc35.
bre538-sup-0003-TableS2.docWord document561KTable SDR2. Summary of LA-ICP-MS U-Pb zircon results for sample xbc19 Summary of LA-ICP-MS U-Pb zircons results for samples of xbc20 and xbc21- xbc48
bre538-sup-0004-TableS3.docWord document100KTable SDR3. Summary of LA-ICP-MS U-Pb zircons results for samples of xbc20 and xbc21.

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