Full Terms & Conditions of access and use can be found athttps://www.tandfonline.com/action/journalInformation?journalCode=tigr20

International Geology Review

ISSN: 0020-6814 (Print) 1938-2839 (Online) Journal homepage: https://www.tandfonline.com/loi/tigr20

Ages of Jurassic volcano-sedimentary stratain the Yanshan Fold-and-Thrust Belt and theirimplications for the coal-bearing strata ofnorthern China

Hai-Long Gao, Yue Zhao, Shuan-Hong Zhang, Jian Liu, Hao Ye, Guo-Can Wang& Jian-Min Liu

To cite this article: Hai-Long Gao, Yue Zhao, Shuan-Hong Zhang, Jian Liu, Hao Ye, Guo-CanWang & Jian-Min Liu (2019) Ages of Jurassic volcano-sedimentary strata in the Yanshan Fold-and-Thrust Belt and their implications for the coal-bearing strata of northern China, InternationalGeology Review, 61:8, 956-971, DOI: 10.1080/00206814.2018.1481459

To link to this article: https://doi.org/10.1080/00206814.2018.1481459

View supplementary material Published online: 13 Jun 2018.

Submit your article to this journal Article views: 154

View related articles View Crossmark data

Citing articles: 1 View citing articles

ARTICLE

Ages of Jurassic volcano-sedimentary strata in the Yanshan Fold-and-ThrustBelt and their implications for the coal-bearing strata of northern ChinaHai-Long Gaoa,b, Yue Zhaob,c, Shuan-Hong Zhangb,c, Jian Liub, Hao Yed, Guo-Can Wanga and Jian-Min Liub

aSchool of Earth Sciences, China University of Geosciences, Wuhan, China; bInstitute of Geomechanics, Chinese Academy of GeologicalSciences, Beijing, China; cKey Laboratory of Paleomagnetism and Tectonic Reconstruction of Ministry of Land and Resources, Beijing, China;dThree Gorges Geotechnical Consultants Co., LTD, Wuhan, China

ABSTRACTJurassic coal-bearing strata are widely distributed in the North China Craton (NCC) and other areasof northern China. These coal-bearing strata were previously considered to be Early–MiddleJurassic in age based on plant fossils, particularly the fossil assemblage of Coniopteris–Phoenicopsis. Since coal-bearing strata are interbedded with volcanic units in the basins of theYanshan Fold-and-Thrust Belt (YFTB), northern NCC, isotopic dating of the volcanic units cantherefore provide age constraints on the coal-bearing strata and the Coniopteris‒Phoenicopsisassemblage. In this paper, we performed a systematic geological survey and present the results ofzircon U–Pb dating of the volcanic units and a pluton in typical basins of the YFTB. These data,combined with the results of previous studies, indicate that the ages of the Nandaling/Xinglonggou, Haifanggou, Jiulongshan, and Tiaojishan/Lanqi formations are 180–168, 169–161,161–157, and 161–153 Ma, respectively. The ages of the interbedded coal-bearing Yaopo andBeipiao formations are constrained to be 169–161 and 177–169 Ma, respectively. Our resultsdemonstrate that both the coal-bearing strata and the Coniopteris‒Phoenicopsis assemblage areMiddle Jurassic in age, which is younger than that previously considered. This fossil assemblageplays a critical role in age constraints on the Jurassic coal-bearing strata. The refinement of its agepermits a more precise dating of the coal-bearing strata, especially in northwestern China, wheredatable interbedded volcanic units are lacking.

● Stratigraphical framework for the Jurassic strata of Yanshan region is established.● The fossil assemblage of Coniopteris‒Phoenicopsis occurred in Middle Jurassic.● The Jurassic coal-bearing strata in northern China are mainly Middle Jurassic.

ARTICLE HISTORYReceived 9 May 2018Accepted 23 May 2018

KEYWORDSCoal-bearing strata;stratigraphic correlation;northern China; YanshanFold-and-Thrust Belt

Introduction

The global average temperature throughout theJurassic was significantly warmer than at present (Reeet al. 2004; Sellwood and Valdes 2006, 2008; Deng et al.2017), which provided favourable conditions for theformation of coal measures. Jurassic coal-bearing strataare widespread throughout Europe (e.g., Fisher andHancock 1985; Petersen 1993; Petersen and Andsbjerg1996; Petersen and Brekke 2001; Barron et al. 2012),northern Africa (e.g., Baioumy 2009; Edress and Abdel-Fatah in press), central Asia (e.g. Moore and Esmaeili2012; Rajabzadeh et al. 2016), western and southernMongolia (Sun et al. 2009), and northern China (e.g.,Vakhrameyev and Doludenko 1977; Hendrix et al. 1995;Wang et al. 2005, 2012; Dai et al. 2009; Ao et al. 2012; Liet al. 2014b, 2018; Guo et al. in press). The coal-bearing

measures in Europe are usually interlayered with marinestrata (Cox and Sumbler 2002; Husinnec and Read2007), and their ages have been well constrained tobe Middle Jurassic. However, the coal-bearing strata innorthern China are non-marine, making it difficult todetermine their ages due to the highly endemic nature,moderate to poor preservation of Jurassic fossils(although the strata are highly fossiliferous), and lackof volcanic units (Hendrix et al. 1995). Although manystudies have been conducted, as a result, there is gen-eral agreement that the strata are as old as Triassic andas young as Middle Jurassic (e.g., Mi et al. 1980; Wu andZhang 1983; Zhang 1983; Chen et al. 1984; He and Wu1986; Wu and Zhou 1986; Li et al. 1988; HBGMR 1989;Zhang and Li 1990; BBGMR 1991; QBGMR 1991; Hendrixet al. 1995; Deng et al. 2003, 2017; Liu and Li 2006;Zhang and Jiang 2010). Fortunately, the contemporary

CONTACT Yue Zhao yue_zhao@cags.ac.cn; yuezhao2307@163.com No. 11 South Minzudaxue Road, Haidian District, Beijing 100081, ChinaSupplementary data can be accessed here.

INTERNATIONAL GEOLOGY REVIEW2019, VOL. 61, NO. 8, 956–971https://doi.org/10.1080/00206814.2018.1481459

© 2018 Informa UK Limited, trading as Taylor & Francis Group

coal-bearing strata in the YFTB (Figures 1 and 2) areinterlayered with volcanic units, providing age con-straints on the basis of isotopic ages of volcanic units

(Figure 3). Zircon U–Pb dating of volcanic units by laserablation–inductively coupled plasma–mass spectrome-try (LA–ICP‒MS) and sensitive high mass-resolution ion

Figure 1. Distribution of Jurassic strata in northern China (modified after Deng et al. 2003).

Figure 2. Simplified tectonic map of the Yanshan Fold-and-Thrust Belt, showing major structures and plutons (modified from Darbyet al. 2004; Liu et al. 2013). The study areas are labelled and include (from west to east) the Western Hills of Beijing, Xiabanchengand Jin–Yang basins. Abbreviations are as follows: NCB = North China Block; SCB = South China Block; WHB = Western Hills ofBeijing; XBCB = Xiabancheng Basin; BPB = Beipiao Basin; JYB = Jin–Yang Basin; YP = Yamenzi Pluton.

INTERNATIONAL GEOLOGY REVIEW 957

microprobe (SHRIMP) were performed with an aim toestablish the Jurassic stratigraphic framework of theYFTB, and provide age constraints on both the coal-bearing strata and their fossil assemblage zones. TheConiopteris–Phoenicopsis plant fossil assemblage iswidely distributed in Eurasia and plays a crucial role inconstraining the ages of Jurassic coal-bearing strata(Sze 1955, 1959; Harris 1964; Mi et al. 1980; Chen et al.1984). Refinement of plant fossil ages enables moreprecise dating of terrestrial coal-bearing strata, espe-cially in northwestern China where the interbeddedvolcanic units are lacking.

Geological background

Regional geology

Jurassic coal-bearing strata are widely distributed in theNCC and other areas of northern China. Divided by theTaihangshan, the Jurassic basins are classified into twotypes: huge, stable basins in the western part of north-ern China; and small, intermontane basins in the east-ern part (Figure 1; Deng et al. 2003; Liu and Li 2006; Liet al. 2018). The Jurassic stratigraphic successions inthese basins are characterized by coal measures in thelower part and red clastic beds in the upper part(Figure 3). Volcanic units are present in the basins ofeastern North China, but not in those of northwestern

China. In the volcano-sedimentary basins, the volcanicunits provide age constraints on the coal-bearing strataand fossil assemblages therein; while the ages of thecoal-bearing strata in northwestern China were mainlydetermined based on fossils, without isotopic age con-straints. Therefore, refinement of the fossil assemblageis helpful in constraining the age of the coal-bearingstrata in basins that lacking datable volcanic units.Three typical basins (from west to east, the WesternHills of Beijing, Xiabancheng, and Jin-Yang basins) inthe YFTB were selected for study (Figure 2(b)), with theaim of establishing the stratigraphic framework andproviding age constraints on both the coal-bearingstrata and their fossil assemblages.

The YFTB is located in the northern NCC and isconsidered to be an intraplate deformation belt thatformed during the late Permian to Early Triassic aftercollision of the Mongolian arc terranes and the NCCalong the Solonker Suture Zone (Figure 2(a); e.g.,Chen 1998; Davis et al. 2001; Xiao et al. 2003; Wanget al. 2007; Liu et al. 2013). The belt experienced a keytransformation from the E–W-trending Paleo-Asian tec-tonic domain to the NNE-trending Paleo-Pacific tectonicdomain (e.g., Zhao 1990; Zhao et al. 1994, 2004a, 2004b;Zhai et al. 2004; Dong et al. 2008), and a series ofvolcano-sedimentary basins formed during theMesozoic (Liu et al. 2004; Liu 2007). The Jurassic strati-graphic successions in the YFTB are characterized by

Figure 3. Previous stratigraphic correlation of Jurassic lithostratigraphic units based on fossils in northern China (complied mainlyfrom Mi et al. 1980; Wu and Zhang 1983; Chen et al. 1984; Li et al. 1988, 2014c; HBGMR 1989; LBGMR 1989; Zheng and Zhang 1990;BBGMR 1991; QBGMR 1991; Hendrix et al. 1995; Deng et al. 2003, 2017; Xu et al. 2005, 2013; Zhang et al. 2016).

958 H.-L. GAO ET AL.

two volcanic units interlayered with coal-bearing strata.The Middle Triassic–Jurassic stratigraphy in previousresearches is shown in Figure 3.

Chronostratigraphic control

The ages of the early Mesozoic strata have pre-viously been constrained by fossils. The XingshikouFormation (consisting of fluvial gravels) wasassigned to the Late Triassic (Mi et al. 1984) orEarly Jurassic (Liu 1988) based on plant and fishfossils, respectively. The coal-bearing Yaopo andBeipiao formations were considered to be Early–Middle Jurassic (Chen et al. 1984; HBGMR 1989;BBGMR 1991) and Early Jurassic (Mi et al. 1980; Wuand Zhang 1983; LBGMR 1989) in age based on floraand sporopollen. The underlying Nandaling/Xinglonggou Formation was therefore constrainedto the Early Jurassic based on the ages of the over-lying units.

Isotopic age dating of volcanic or pyroclastic bedscan be used to constrain the ages of interbedded strata(Meng et al. 2014). The detrital zircon grains in theXingshikou Formation of the Xiabancheng Basin are asyoung as 197 ± 6 Ma (Liu et al. 2012), implying an EarlyJurassic age. Inherited zircon grains from the Nandalingflood basalt in the Western Hills of Beijing yielded apeak age of 174 ± 8 Ma, which was inferred to repre-sent the eruption age of the Nandaling Formation(Zhao et al. 2006). A biotite 40Ar–39Ar age of180 ± 2 Ma was reported from the base of theNandaling Formation in northern Hebei (Davis et al.2001), and a similar SHRIMP zircon U–Pb age of177 ± 4 Ma was obtained from the equivalentXinglonggou Formation in the Beipiao Basin in westernLiaoning (Yang and Li 2008). An LA–ICP–MS zircon U–Pb age of 163 ± 1 was reported from a tuff layer in thelower part of the Jiulongshan Formation (Chen et al.2014; Zhang et al. 2014). Chang et al. (2014) reported aplagioclase 40Ar–39Ar age of 167 ± 1 Ma for interbeddedtuff in the middle part of the Haifanggou Formation inthe Beipiao Basin. Recently, Huang (2017) also reporteda similar zircon U–Pb age of 167 ± 1 Ma from thetuffaceous breccia at the base of the HaifanggouFormation. The lower age limits of volcanic rocks fromthe Tiaojishan Formation (in western Beijing and north-ern Hebei) are 161–157 Ma (Davis et al. 2001; Cope2003; Zhao et al. 2004b; Liu et al. 2006; Cope et al.2007). Two plagioclase 40Ar–39Ar ages of 161 ± 1 Maand 159 ± 1 Ma were obtained from tuff at the base of

the Lanqi Formation in the Beipiao Basin (Chang et al.2009).

Samples and methods

Sampling and description of cross-sections

Volcanic and clastic deposits occur alternately in thevolcano-sedimentary basins of the present study, mean-ing that the volcanic units can provide valuable abso-lute age constraints on the stratigraphic framework.Jurassic volcanic rocks and plutons in typical basins ofthe YFTB have been dated to establish the stratigraphicframework in the YFTB.

In the Western Hills of Beijing, geochronological stu-dies have been performed on the Nandaling andTiaojishan formations, while data on the latter aremore robust than those on the former (e.g., Daviset al. 2001; Liu et al. 2006; references therein). TheNandaling volcanic rocks disconformably overlie theXingshikou Formation (BBGMR 1991) and unconform-ably overlie the Paleozoic strata (Bao et al. 1983; Yanget al. 2006). The Tiaojishan Formation overlies theJiulongshan Formation (Figures 3, 4(a) and 5; Wong1927, 1929) across an angular unconformity. Andesitesamples were collected from the lower part of theNandaling Formation in the Fachengkou Section (sam-ple 150904–1) and from the base of the TiaojishanFormation (sample 010907–4). The sampling locationsare marked in Figure 5.

In the Xiabancheng Basin, the Yamenzi syenite pluton isoverlain by the Jiulongshan Formation across a nonconfor-mity (Figure 6). The age of the pluton provides a reliableconstraint on the age of the Jiulongshan Formation.Sample 1021 was collected from the pluton (Figure 6).

Figure 7 provides cross-sections of the HaifanggouFormation in Nanpiao County at the southeastern mar-gin of the Jin–Yang Basin. The Haifanggou Formation inNanpiao was previously considered to be the EarlyJurassic Xinglonggou Formation. A typical MiddleJurassic fossil assemblage (Coniopteris–Phoenicopsis)was identified in the sedimentary layers, and this for-mation was reassigned to the Middle JurassicHaifanggou Formation (LBGMR 1989). The HaifanggouFormation in Nanpiao County overlies the TriassicHongla or Houfulongshan formations, and underliesthe Late Jurassic Lanqi Formation across angular uncon-formities (Figure 4(b); LBGMR 1989). The HaifanggouFormation is divided into three units: conglomeratesin the lower part (Figure 4(c)); volcanic and pyroclasticrocks in the middle part (Figure 4(d‒g)); and coal-

INTERNATIONAL GEOLOGY REVIEW 959

bearing sandstones and mudstones in the upper part(Figure 4(h)). Cross-sections and sample locations aremarked in Figure 7. Four andesitic samples were

collected from the Dawopu–Aijiagou andHoufulongshan–Pandaogou sections. Field photo-graphs of the samples are shown in Figure 4.

Figure 4. Field photographs showing contact relations and samples from the Yanshan Fold-and-Thrust Belt: (a) angular unconfor-mity beneath the Tiaojishan Formation in the Western Hills of Beijing; (b) angular unconformity beneath the Haifanggou Formationin western Liaoning; (c) conglomerate at the base of the Haifanggou Formation; (d) sample 15132; (e) sample 15127; (f) sample08077; (g) sample 08079–2; and (h) coal measures in the upper part of the Haifanggou Formation. Abbreviations are as follows:J2y = Middle Jurassic Yaopo Formation; J3t = Upper Jurassic Tiaojishan Formation; J2–3h = Middle–Upper Jurassic HaifanggouFormation; and T2h = Middle Jurassic Houfulongshan Formation.

960 H.-L. GAO ET AL.

Figure 5. Geological sketch map of the Western Hills of Beijing and cross-section (modified from BBGMR 1991). A–A’: Fachengkousection.

Figure 6. Geological sketch map, photograph and cross-section of the Yamenzi Pluton in the Pingquan region of northern Hebei(modified from Liu et al. 2006, 2012).

INTERNATIONAL GEOLOGY REVIEW 961

Methods

The samples were cleaned prior to zircon separation,and the separated zircon grains were mounted in epoxyresin, polished, and gold-coated. The grains werephotographed in transmitted and reflected light, andimaged by cathodoluminescence (CL) (Figure 8). Thezircon U–Pb isotopic analyses were conducted usingan Agilent 7700 LA–ICP–MS instrument at SampleSolution Analytical Technology, Wuhan, China, andusing an Agilent 7500 LA–ICP–MS instrument at theState Key Laboratory of Continental Dynamics,Northwest University, Xi’an, China. The analytical proce-dure is described in detail by Liu et al. (2008, 2010). Theoff-line data selection and integration of backgroundand signals, time-drift correction, and quantitative cali-bration were conducted using ICPMSDataCal 8.3 (Liu

et al. 2010) and GLITTER 4.0 (Macquarie University) soft-ware. Zircon U–Pb concordia and weighted mean ageplots were produced using Isoplot/Ex_ver3 (Ludwig2003). The analytical results are listed inSupplementary Table 1.

Zircon SHRIMP U–Pb analyses were conducted usinga SHRIMP II at the Beijing SHRIMP Centre, Beijing, China,following the procedures and methods of Williams et al.(1998) and Jian et al. (2003). Isoplot version 3 (Ludwig2003) was used for off-line data processing. The analy-tical results are listed in Supplementary Table 2.

Results

The zircon grains from the volcanic rocks and plutonare euhedral with sizes of 20–200 μm and length:width

Figure 7. Geological sketch map and cross-sections of the western Liaoning area. (a) The Jin–Yang Basin; and (b) the NanpiaoCounty, western Liaoning (modified from Liaoning Bureau of Geology and Mineral Resources (LBGMR) 1989; He et al. 2007).

962 H.-L. GAO ET AL.

ratios of 4:1. The analyzed grains exhibit a wide rangeof Th and U contents, with Th/U ratios of 0.14–4.52.Most of the zircon grains are elongate columnar inshape, and others are short columnar in CL (Figure 8).The majority of the grains are igneous zircons, andthose with obvious oscillatory zoning in CL and smoothsignals in ICPMSDataCal 8.3 were selected for isotopicage calculation. The age data are listed inSupplementary Tables 1 and 2, and the concordantanalyses are shown in concordant and weighted meanplots in Figure 9.

Andesite sample 150904–1 was collected from thebase of the Nandaling Formation (Figure 5). In total 19of the 25 analyses yield a weighted mean age of172 ± 2 Ma (MSWD = 1.7; Figures 9(a) and 10).Andesite sample 010907–4 was collected from theTiaojishan Formation near Malan (Figure 5). Six zircongrains are inherited, and 14 concordant analyses from

the other 18 grains yield a concordia age of 157 ± 2 Maand a weighted mean age of 157 ± 3 Ma (MSWD = 0.26;Figure 9(b)). The analyzed ages of the Yamenzi syenitepluton (Figure 6; sample 1021) are 168–153 Ma, and 12of 15 analyzed grains yield a concordia age of161 ± 2 Ma (MSWD = 2.2) and a weighted mean ageof 161 ± 3 Ma (MSWD = 0.58; Figure 9(c)). Sample 15132is an autochthonous andesite collected from the lowestvolcanic unit overlying the conglomerates at the baseof the Haifanggou Formation (Figures 4(d), 7 and 10).Seven concordant analyses of 16 grains from this sam-ple yield a concordia age of 169 ± 1 Ma and a weightedmean age of 169 ± 2 Ma (MSWD = 1.6; Figure 9(d)).Sample 15127 is an andesite collected from the base ofthe Haifanggou Formation (Figures 4(e), 7 and 10),which yields ages of 160–170 Ma. Nine concordantanalyses yield a concordia age of 164 ± 1 Ma and aweighted mean age of 164 ± 2 Ma (MSWD = 1.2;

Figure 8. Cathodoluminescence images of representative zircons from six samples of Jurassic volcanic rocks from typical basins ofthe Yanshan Fold-and-Thrust Belt. Circles show the location of analyses, and the resulting age is noted below each zircon.

INTERNATIONAL GEOLOGY REVIEW 963

Figure 9(e)). Sample 08077–1 is an andesite collectedfrom the lower part of the Haifanggou Formation(Figures 4(f), 7 and 10). Six inherited zircon grainsfrom the 22 analyses yield ages of 2500–2210 Ma, and

the other 13 concordia ages are 170–156 Ma with aconcordia age of 166 ± 3 Ma and a weighted mean ageof 164 ± 2 Ma (MSWD = 0.78; Figure 9(f)). The andesiticsample 08079–2 was collected from the middle part of

Figure 9. Zircon U–Pb concordia and weighted mean age plots for samples from Jurassic volcanic rocks and the pluton in theYanshan Fold-and-Thrust Belt, North China. (a) Sample 150904–1, from the lower part of the Nandaling Formation; (b) sample010907–4, from the base of the Tiaojishan Formation; (c) sample 1021 from the Yamenzi Pluton; (d) sample 15132, from the base ofthe Haifanggou Formation; (e) sample 15127, from the lower part of the Haifanggou Formation; (f) sample 08077–1, from themiddle part of the Haifanggou Formation; and (g) sample 08079–2, from the middle part of the Haifanggou Formation.

964 H.-L. GAO ET AL.

the Haifanggou Formation (Figures 4(g), 7 and 10).Eight concordant analyses of the 16 analyzed grainsyield a concordia age of 165 ± 2 Ma and a weightedmean age of 165 ± 3 Ma (MSWD = 2; Figure 9(g)).

Discussion

Ages of volcanic strata

Nandaling/Xinglonggou formationThe Nandaling and Xinglonggou formations were pre-viously considered to be equivalent strata (Figure 2;LBGMR 1989; Xu et al. 2005). Yang and Li (2008)reported a SHRIMP zircon U–Pb age of 177 ± 4 Ma fora tuff sample collected from the XinglonggouFormation (Figure 11). The andesite sample 150904–1collected from the base of the Nandaling Formation inthe Fachengkou Section yields a LA–ICP–MS zircon ageof 172 ± 2 Ma (Figures 10 and 11). We reported zirconU–Pb ages of 175–168 Ma for the Nandaling Formationfrom the Caihongqiao Section in the Western Hills ofBeijing (Figures 10 and 11; Gao et al. 2018). Davis et al.(2001) reported a biotite 40Ar–39Ar age of 180 ± 2 Mafor silicic tuff in northern Hebei (Figure 11). The earliest

Jurassic magmatic activity in the YFTB is therefore con-strained to 180–168 Ma (Figure 11).

Jiulongshan FormationThe andesite sample 010907–4 was collected from thebase of the Tiaojishan Formation in the Western Hills ofBeijing and yields a zircon SHRIMP U–Pb age of157 ± 3 Ma (Figures 5 and 11), providing an upperlimit age for the Jiulongshan Formation. In northernHebei, the reported lower age limit of the JiulongshanFormation is 163 ± 2 Ma (Chen et al. 2014; Zhang et al.2014). The emplacement age of the Yamenzi Pluton(sample 1021) is 161 ± 3 Ma. The JiulongshanFormation nonconformably overlies the pluton, thussuggesting that the Jiulongshan Formation is youngerthan 161 ± 3 Ma (within error of the 163 ± 2 Ma age).For convenience, we provisionally refer to the age of161 ± 3 Ma for the lower limit age of the JiulongshanFormation in this paper. The lower age limits of theTiaojishan/Lanqi Formation are 161–157 Ma (Zhaoet al. 2004a; Liu et al. 2006; references therein; Ma andZheng 2009; Chang et al. 2014; Yu et al. 2016).Therefore, the age of the Jiulongshan Formation isconstrained to 161–157 Ma.

Figure 10. Correlation of stratigraphic columns from the western Beijing and western Liaoning areas. Abbreviations are as follows:J3l–j = Longmen + Jiulongshan formations; J3l = Lanqi Formation; J3t = Tiaojishan Formation; J2–3y = Yaopo Formation;J2–3h = Haifanggou Formation; J2n = Nandaling Formation; J1 x = Xingshikou Formation; T1h = Hongla Formation;T3h = Houfulongshan Formation. Data are sourced from: (I) Gao et al. (2018); (II) this paper; (III) Zhao et al. (2006); (IV) Changet al. (2009); (V) Chang et al. (2014).

INTERNATIONAL GEOLOGY REVIEW 965

Haifanggou FormationIn the western Liaoning area, samples from the lower tomiddle parts of the Haifanggou Formation yielded agesof 169–164 Ma (Figure 9). The lower age limit of the tuffat the base of the Lanqi Formation is 161 ± 1 Ma(Chang et al. 2009). Therefore, the age of theHaifanggou Formation is constrained to 169–161 Ma.

Tiaojishan/Lanqi FormationPrevious studies have constrained the eruption ages ofthe volcanic units of the Tiaojishan/Lanqi Formation to~161–153 Ma (Liu et al. 2006; references therein; Maand Zheng 2009; Chang et al. 2014; Li et al. 2014a, 2016;Yu et al. 2016).

Ages of coal-bearing strata

The coal-bearing strata in the YFTB were previouslyconsidered to be Early–Middle Jurassic in age due tothe abundant plant fossils correlating with the JurassicYorkshire Flora in the UK (Harris 1964; Chen et al. 1984;Zhao et al. 2002). The Jurassic strata in the UK aresubdivided into stages based on the widely distributedand fast-evolving ammonites (Cox and Sumbler 2002).The Yorkshire Flora occurs mainly in the Middle JurassicRavenscar Group, whose age is authentic owing to theconstraints of ammonites in marine strata. More than 20species (~20% of the identified fossils) in the Western

Hills of Beijing are the same as, or similar to, theYorkshire Flora (Harris 1964; Chen et al. 1984). Sometypical Early–Middle Jurassic species occur in bothYorkshire and western Beijing, such as Coniopterishymenophylloides, C. tatungensis, and Ehoracia lobifolia(Chen et al. 1984). Some species that are commonlypreserved in the Triassic–Early Jurassic strata are alsofound in the lower part of the Yaopo Formation (Chenet al. 1984). The Yaopo Formation was therefore con-strained to the Early–Middle Jurassic on the basis of theabove observations (Chen et al. 1984; BBGMR 1991). Miet al. (1980) constrained the Beipiao Formation to theEarly Jurassic based on large numbers of Neocalamites,Dictyophyllum, and Clathropteris, few Conopteris, and notypical Triassic species. Abundant floral fossils (includ-ing Coniopteris) were identified in the HaifanggouFormation and assigned as Middle Jurassic flora (Miet al. 1980; Pan 1983). The dating of strata on thebasis of slowly evolving flora is not sufficiently accurate;instead, isotopic ages of volcanic units can providemore precise age estimates.

The ages of the coal-bearing strata can be con-strained by dating the volcanic units. As shown inFigure 3, the overlying strata are the Longmen,Jiulongshan, and Haifanggou formations, and theunderlying strata are the Nandaling andXinglonggou formations. Their ages are listed inSupplementary Table 3. The age of the Jiulongshan

Figure 11. Revised stratigraphic correlation of Jurassic strata in northern China (descriptions and data are from Li et al. 1988; Daviset al. 2001; Deng et al. 2003; Peng et al. 2003; Ge 2004; Zhao et al. 2004a; Liu et al. 2006; Yang et al. 2006; Zhao 2007; Yang and Li2008; Chang et al. 2009; Ge et al. 2010; Li et al. 2013, 2014c; Hu 2014; Meng et al. 2014; Huang 2017). ‘?’ represents the debatedstratigraphic contact relationship.

966 H.-L. GAO ET AL.

Formation is 161–157 Ma (Zhao et al. 2004a; Li et al.2014a; this study) and the upper age limit of theNandaling Formation is 168 ± 2 Ma (Gao et al.2018). Therefore, the age of the coal-bearing stratain the Western Hills of Beijing is constrained to168–161 Ma. The ages obtained for the HaifanggouFormation (169–164 Ma) and the reported age of theXinglonggou Formation (177 ± 4 Ma; sample collectedfrom the middle part of the formation; Yang and Li2008) suggest that the age of the Beipiao Formationis 177–169 Ma (Figure 9). The Beipiao Formation istherefore older than the Yaopo Formation. The dis-parity in ages of the two formations explains theabundant Coniopteris in the Yaopo Formation, andthe scarcity of the fossil in the Beipiao Formation.The coal-bearing strata in the YFTB were formedmainly during the Middle Jurassic, not the EarlyJurassic as previously suggested (Chen et al. 1984;Mi et al. 1984; LBGMR 1989; BBGMR 1991).

As one of the typical Middle Jurassic fossil assem-blages, Coniopteris–Phoenicopsis, occurs in the upperpart of the Beipiao Formation in the YFTB (177–169 Ma; Yang and Li 2008; this study). This fossil assem-blage has been considered to be Early–Middle Jurassicin age in China (Sze 1955, 1959; Chen et al. 1984). Somestrata containing this fossil assemblage, such as theYongdinghe and Fuxian formations (Figure 3), are stillconsidered to be Early Jurassic in age. Many Jurassicunits in northern China were assigned older ages byprevious studies, which has been proved by recentstudies (Ge 2004; Yang et al. 2006; Zhao 2007; Geet al. 2010; Li et al. 2013, 2014c). Based on the plantfossil, the stratigraphic correlations are revised andshown in Figure 11.

A global arid climate was indicated by the appearanceof Late Jurassic evaporates in Europe and northern Africa,and the mottled and red Upper Jurassic sediments incentral Asia and northern China (Vakhrameyev andDoludenko 1977; Zheng and Zhang 1990). The basins innorthern China experienced compressional deformationand were completely or partially uplifted during theMiddle–Late Jurassic (Hendrix et al. 1992; Jolivet 2015;Van Der Voo et al. 2015; Fang et al. 2016; Yang et al.2017). The disappearance of coal-bearing strata was exa-cerbated by both the arid global climate and the uplift ofnorthern China during the Late Jurassic.

Conclusions

(1) The ages of the Nandaling and Haifanggou for-mations in the YFTB are constrained to180–169 Ma and 169–161 Ma, respectively.

(2) The Jurassic coal-bearing strata in the YFTB aremainly Middle Jurassic in age, not Early Jurassicas was previously suggested. The BeipiaoFormation in western Liaoning (177–169 Ma) isolder than the Yaopo Formation in the WesternHills of Beijing (168–161 Ma).

(3) The Coniopteris–Phoenicopsis fossil assemblage,previously considered to be Early–Middle Jurassicin age, is revised to the Middle Jurassic based onour dating of volcanic units in the YFTB. Therevised age of this fossil assemblage suggeststhat the coal-bearing strata in northern China aremainly Middle Jurassic in age.

Geolocation information

The study area is located at the northern margin of the NCC(39°30ʹ–42°30ʹN, 114°–123°E).

Acknowledgments

We gratefully acknowledge the anonymous reviewers and DrRobert J. Stern (editor-in-chief) for their valuable and construc-tive reviews and comments which greatly improve the manu-script. We thank Zi-Bo Fu, Qi-Qi Zhang for their help in the fieldinvestigation. Xiao-Ming Liu and Xiao-Li Shi are acknowledgedfor technical support during the zircon U–Pb analyses.

Disclosure statement

No potential conflict of interest was reported by the authors.

Funding

This study was financially supported by the fund from theMinistry of Science and Technology of People’s Republic ofChina, under Grant [Number, 2016YFC0600108-4] and [theNational Natural Science Foundation of China], under Grant[number 41725011 and 41572204].

References

Ao, W.H., Huang, W.H., Weng, C.M., Xiao, X.L., Liu, D.M., Tang,X.Y., Chen, P., Zhao, Z.G., Wan, H., and Finkelman, R.B., 2012,Coal petrology and genesis of Jurassic coal in the OrdosBasin, China: Geoscience Frontiers, v. 3, no. 1, p. 85–95.

Baioumy, H.M., 2009, Mineralogical and geochemical charac-terization of the Jurassic coal from Egypt: Journal of AfricanEarth Sciences, v. 54, p. 75–84. doi:10.1016/j.jafrearsci.2009.03.003

Bao, Y.G., Xie, D.Y., Chen, Z.B., and Mo, B.T., 1983, On theYanshan movement in Beijing area: Acta Geologica Sinica,v. 2, p. 195–204. In Chinese with English abstract.

Barron, A.J.M., Lott, G.K., and Riding, J.B., 2012, Stratigraphicalframework for the Middle Jurassic strata of Great Britain

INTERNATIONAL GEOLOGY REVIEW 967

and the adjoining continental shelf: British GeologicalSurvey Research Report, 177 p.

Beijing Bureau of Geology and Mineral Resources (BBGMR),1991, Geological Memoirs of Beijing: Beijing, GeologicalPublishing House, p. 613 p. In Chinese.

Chang, S.C., Zhang, H., Hemming, S.R., Mesko, G.T., and Fang,Y., 2014, 40Ar–39Ar age constraints on the Haifanggou andLanqi formations: When did the first flowers bloom:Geological Society of London Special Publications, v. 378,p. 277–284. doi:10.1144/SP378.1

Chang, S.C., Zhang, H., Renne, P.R., and Fang, Y., 2009, High–Precision 40Ar–39Ar age constraints on the basal of LanqiFormation and its implications for the origin of angiospermplants: Earth and Planetary Science Letters, v. 279, no. 3, p.212–221. doi:10.1016/j.epsl.2008.12.045

Chen, A., 1998, Geometric and kinematic evolution of base-ment–Cored structures: Intraplate orogenesis within theYanshan orogen, northern China: Tectonophysics, v. 292,no. 1, p. 17–42. doi:10.1016/S0040-1951(98)00062-6

Chen, F., Dou, Y.W., and Huang, Q.S., 1984, The flora in theWestern Hills of Beijing, China: Beijing, Geology PublishingHouse, p. 136 . In Chinese with English summary.

Chen, H.Y., Zhang, Y.Q., Zhang, J.D., Fan, Y.G., Peng, Q.P., Lian,Q., Sun, L.P., and Yu, L., 2014, LA–ICP–MS zircon U–Pb ageand geochemical characteristics of tuff of JiulongshanFormation from Chengde Basin, northern Hebei:Geological Bulletin of China, v. 33, no. 7, p. 966–977. InChinese with English abstract.

Cope, T.D., 2003, Sedimentary evolution of the Yanshan Fold-Thrust Belt, Northeast China [Ph. D thesis]: StanfordUniversity, 230 p.

Cope, T.D., Shultz, M.R., and Graham, S.A., 2007, Detrital recordof Mesozoic shortening in the Yanshan belt, North China:Testing structural interpretations with basin analysis: BasinResearch, v. 19, no. 2, p. 253–272. doi:10.1111/j.1365-2117.2007.00321.x

Cox, B.M., and Sumbler, M.G., 2002, British Middle JurassicStratigraphy, Geological Conservation Review Series, no. 26:Peterborough, Joint Nature Conservation Committee, p.508. ISBN: 1861074794

Dai, J.X., Zou, C.N., Li, J., Ni, Y.Y., Hu, G.Y., Zhang, X.B., Liu, Q.Y.,Yang, C., and Hu, P., 2009, Carbon isotopes of Middle–Lower Jurassic coal–derived alkane gases from the majorbasins of northwestern China: International Journal of CoalGeology, v. 80, p. 124–134. doi:10.1016/j.coal.2009.08.007

Darby, B.J., Davis, G.A., Zhang, X.H., Wu, F.Y., Wilde, S., andYang, J.H., 2004, The newly discovered Waziyu metamorphiccore complex, Yiwul Shan, western Liaoning Province, NorthChina: Earth Science Frontiers, v. 11, no. 3, p. 145–155.

Davis, G.A., Zheng, Y.D., and Wang, C., 2001, Mesozoic tectonicevolution of the Yanshan fold and thrust belt with emphasison Hebei and Liaoning provinces, northern China: GeologicalSociety of America Memoir, v. 194, v. 10, no. 2, p. 171–197.

Deng, S.H., Lu, Y.Z., Zhao, Y., Fan, R., Wang, D.D., Yang, X.J., Li,X., and Sun, B.N., 2017, The Jurassic palaeoclimate regiona-lization and evolution of China: Earth Science Frontiers, v.24, no. 1, p. 106–142. In Chinese with English abstract.

Deng, S.H., Yao, Y.M., Ye, D.Q., Chen, P.J., Jin, F., Zhang, Y.J., Xu,K., Zhao, Y.W., Yuan, X.Q., and Zhang, S.B., 2003, TheJurassic strata in northern China: Beijing, PetroleumPublishing House, p. 399. In Chinese.

Dong, S.W., Zhang, Y.Q., Long, C.X., Yang, Z.Y., Ji, Q., Wang, T.,Hu, J.M., and Chen, X.H., 2008, Jurassic tectonic revolutionin China and new interpretation of the “YanshanMovement: Acta Geologica Sinica, v. 82, no. 2, p. 334–347.

Edress, N.A.A., and Abdel-Fatah, A.R., in press, Fuel analysesand rank determination of the Egyptian Maghara main coalseam, north central Sinai: Egypt, Egyptian Journal ofPetroleum.

Fang, Y.N., Wu, C.D., Wang, Y.Z., Wang, L.X., Guo, Z.J., and Hu,H.W., 2016, Stratigraphic and sedimentary characteristics ofthe Upper Jurassic–Lower Cretaceous strata in the JugggarBasin, Central Asia: Tectonic and climate implications:Journal of Asian Earth Sciences, v. 129, p. 294–308.doi:10.1016/j.jseaes.2016.09.001

Fisher, M.J., and Hancock, N.J., 1985, The Scalby Formation(Middle Jurassic, Ravenscar Group) of Yorkshire:Reassessment of age and depositional environment:Proceedings of the Yorkshire Geological Society, v. 45, no.4, p. 293–298. doi:10.1144/pygs.45.4.293

Gao, H.L., Zhao, Y., Ye, H., Zhang, S.H., Liu, J., and Wang, G.C.,2018, Dating Jurassic volcanic rocks in the Western Hills ofBeijing, North China: Implications for the initiation of theYanshanian tectonism and subsequent thermal events:Journal of Asian Earth Sciences, v. 161, p. 164–177.

Ge, Y.H., 2004, The Middle Jurassic stratigraphy and flora innortheastern margin of Ordos Basin [Master thesis]: Jilin,Jilin University, 46 p. [In Chinese with English abstract.]

Ge, Y.H., Sun, C.L., and Wang, Y.F., 2010, The flora fromZhaogou Formation in Shiguai Basin, Inner Mongolia andthe geological age: Global Geology, v. 29, no. 2, p. 175–180.In Chinese with English abstract.

Guo, P., Liu, C.Y.,Wang, J.Q., Deng, Y., Mao, G.Z., andWang,W.Q., inpress, Detrital–Zircon geochronology of the Jurassic coal-bear-ing strata in the western Ordos Basin, North China: Evidencesfrom multi-cycle sedimentation: Geoscience Frontiers.

Harris, T.M., 1964, The Yorkshire Jurassic flora II, Caytoniales,Cycadales and Pteridosperms: London, British MuseumNatural History, p. 191.

He, Y.L., and Wu, X.W., 1986, Middle Jurassic Aalenian flora ofChina: Acta Palaeontologica Sinica, v. 25, p. 591–601.InChinese with English abstract.

He, Z.J., Niu, B.G., and Zhang, X.Y., 2007, Provenance analysisof the conglomerate clastic compositions from the LateJurassic Chengde Basin and its tectonic significance: ActaPetrological Sinica, v. 23, no. 3, p. 655–666. In Chinese withEnglish abstract.

Hebei Bureau of Geology and Mineral Resources (HBGMR),1989, Geological Memoirs of Hebei: Beijing, GeologicalPublishing House, p. 613. In Chinese.

Hendrix, M.S., Brassell, S.C., Carroll, A.R., and Graham, S.A.,1995, Sedimentology, organic geochemistry, and petro-leum potential of Jurassic coal measures: Tarim, Junggarand Turpan Basins, northwest China: AAPG Bulletin, v. 79,no. 7, p. 929–959.

Hendrix, M.S., Graham, S.A., Carroll, A.R., Sobel, E.R., Mcknight,C.L., Schulein, B.J., and Wang, Z.X., 1992, Sedimentaryrecord and climatic implications of recurrent deformationin the tian shan: evidence from mesozoic strata of thenorth tarim, South Junggar, and Turpan Basins, NorthwestChina: Geological Society Of America Bulletin, v. 104, no. 1,p. 53–79.

968 H.-L. GAO ET AL.

Hu, Q.Y., 2014, Sporopollen assemblages and chronostratigra-phy from the Late Jurassic Qigu Formation in southernJunggar Basin, Xinjiang [Master thesis]: China University ofGeosciences (Beijing), China, 50 p. [In Chinese with Englishabstract.]

Huang, D.Y., 2017, The age of Haifanggou Formation and itsstratigraphic significance: Gondwana InternationalConference 16th, Bangkok, Abstracts, p. 124.

Husinnec, A., and Read, J.F., 2007, The Late Jurassic Tithonian,a greenhouse phase in the Middle Jurassic–EarlyCretaceous “cool” mode: Evidence from the cyclic AdriaticPlatform, Croatia: Sedimentology, v. 54, p. 317–337.doi:10.1111/j.1365-3091.2006.00837.x

Jian, P., Liu, D.Y., and Sun, X.M., 2003, SHRIMP dating ofCarboniferous Jinshajiang Ophiolite in western Yunnan andSichuan: Geochronological constraints on the evolution ofthe Paleo-Tethys oceanic crust: Acta Geologica Sinica, v. 77,no. 2, p. 217–228. In Chinese with English abstract.

Jolivet, M., 2015, Mesozoic tectonic and topographic evolu-tion of Central Asia and Tibet: A preliminary synthesis, inBrunet, M.F., McCann, T., and Sobel, E.R., eds., Geologicalevolution of Central Asian Basins and the Western TienShan Range: Geological Society, London, special publica-tions, v. 427, p. 17.

Li, C.M., Zhang, C.H., Cope, T.D., and Lin, Y., 2016, Out-of-sequence thrusting in polycyclic thrust belts: An examplefrom the Mesozoic Yanshan belt, North China Craton:Tectonics, v. 35, p. 2082–2116. doi:10.1002/2016TC004187

Li, H.L., Zhang, H.G., Qu, H.J., Cai, X.M., and Wang, M., 2014a,Initiation, the first stage of the Yanshan (Yenshan)Movement in Western Hills, constraints from zircon U–Pbdating: Geological Review, v. 60, no. 5, p. 1026–1042. InChinese with an English abstract.

Li, M., Shao, L.Y., Lu, J., Spiro, B., Wen, H.J., and Li, Y.H., 2014b,Sequence stratigraphy and paleogeography of the MiddleJurassic coal measures in the Yuqia coalfield, northernQaidam Basin, northwestern China: AAGP Bulletin, v. 98,no. 12, p. 2531–2550. doi:10.1306/06041413129

Li, P.J., He, Y.L., Wu, X.W., Mei, S.W., and Li, B.Y., 1988, Early andMiddle Jurassic strata and their floras from northeasternborder of Qaidam Basin: Qinghai, Nanjing University, p.231. In Chinese with English abstract.

Li, Z.H., Dong, S.W., and Qu, H.J., 2013, Timing of the initiationof the Jurassic Yanshan movement on the North ChinaCraton: Evidence from sedimentary cycles, heavy minerals,geochemistry, and zircon U–Pb geochronology:International Geology Review, v. 56, no. 3, p. 288–312.doi:10.1080/00206814.2013.855013

Li, Z.H., Feng, S.B., Yuan, X.Q., and Qu, H.J., 2014c, Chronologyand its significance of the Lower Jurassic tuff in Ordos Basinand its periphery: Oil and Gas Geology, v. 35, no. 5, p. 729–741. In Chinese with English abstract.

Li, Z.X., Wang, D.D., Lv, D.V., Li, Y., Liu, H.Y., Wang, P.L., Liu, Y.,Liu, J.Q., and Li, D.D., 2018, The geologic settings of Chinesecoal deposits: International Geology Review, v. 60, no. 5–6,p. 548–578. doi:10.1080/00206814.2017.1324327

Liaoning Bureau of Geology and Mineral Resources (LBGMR),1989, Geological Memoirs of Liaoning: Beijing, GeologicalPublishing House, p. 613. In Chinese.

Liu, J., Zhao, Y., and Liu, X.M., 2006, Age of the TiaojishanFormation volcanics in the Chengde Basin, northern Hebei

province: Acta Petrologica Sinica, v. 22, no. 11, p. 2617–2630. In Chinese with English abstract.

Liu, J., Zhao, Y., Liu, X.M., Wang, Y., and Liu, X., 2012, Rapidexhumation of basement rocks along the northern marginof the North China Craton in the early Jurassic: Evidencefrom the Xiabancheng Basin, Yanshan tectonic belt: BasinResearch, v. 24, no. 5, p. 544–558. doi:10.1111/bre.2012.24.issue-5

Liu, S.F., 2007, Early Mesozoic basin development and itsresponse to thrusting in the Yanshan fold and thrust belt,China: International Geology Review, v. 49, p. 1025–1049.doi:10.2747/0020-6814.49.11.1025

Liu, S.F., Su, S., and Zhang, G.W., 2013, Early Mesozoic basindevelopment in North China: Indications of cratonic defor-mation: Journal of Asian Earth Sciences, v. 62, p. 221–236.doi:10.1016/j.jseaes.2012.09.011

Liu, S.F., Zhang, J.F., Li, Z., and Wang, Q.C., 2004, Late Jurassicbasin–fill record and its implication for basin margin tec-tonism, Chengde, Yanshan Mountains, North China: EarthScience Frontiers, v. 11, no. 3, p. 245–254. In Chinese withEnglish abstract.

Liu, X.T., 1988, A new palaeoniscoid fish from XingshikouFormation of Western Hills of Beijing: Vertebrata Palaslatica,v. 26, no. 4, p. 278–286. In Chinese with English abstract.

Liu, Y., Gao, S., Hu, Z., Gao, C., Zong, K., and Wang, D., 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 zirconsfrom mantle xenoliths: Journal of Petrology, v. 51, no. 1–2,p. 392–399. doi:10.1093/petrology/egp082

Liu, Y., Hu, Z., Gao, S., Günther, D., Xu, J., and Gao, C., 2008, Insitu analysis of major and trace elements of anhydrousminerals by LA–ICP–MS without applying an internal stan-dard: Chemical Geology, v. 1–2, p. 34–43. doi:10.1016/j.chemgeo.2008.08.004

Liu, Y., and Li, L., 2006, Preliminary analysis on the similaritycoefficient study of representative Jurassic floras fromChina: Chinese Bulletin of Botany, v. 23, no. 4, p. 380–388.In Chinese with English abstract.

Ludwig, K.R., 2003, User’s manual for Isoplot 3.00. A geochro-nological toolkit for Microsoft Excel. BerkeleyGeochronology Centre: Berkeley, California, SpecialPublication no.4a, p. 70.

Ma, Q., and Zheng, J.P., 2009, In-situ U–Pb dating and Hfisotopic analyses of zircons in the volcanic rock of theLanqi Formation in the Beipiao area, western LiaoningProvince: Acta Petrologica Sinica, v. 25, no. 12, p. 3287–3297. In Chinese with English abstract.

Meng, Q.R., Wei, H.H., Wu, G.L., and Duan, L., 2014, EarlyMesozoic tectonic settings of the northern North ChinaCraton: Tectonophysics, v. 611, no. 1, p. 155–166.doi:10.1016/j.tecto.2013.11.015

Mi, J.R., Xu, K.Z., Zhang, C.B., Chang, J.P., and Yao, P.Y., 1980,Mesozoic strata in Beipiao, Liaoning, China: Journal ofChangchun Institute of Geology, v. 4, p. 20–39.In Chinese.

Mi, J.R., Zhang, C., Sun, C., Ning, Y., and Yao, C., 1984, On thecharacteristics and the geologic age of the XingshikouFormation in the Western Hills of Beijing: Acta GeologicaSinica, v. 04, p. 273–284.In Chinese with English abstract.

Moore, F., and Esmaeili, A., 2012, Mineralogy and geochemis-try of the coals from the Karmozd and Kiasar coal mines,

INTERNATIONAL GEOLOGY REVIEW 969

Mazandaran province, Iran: International Journal of CoalGeology, v. 96–97, p. 9–21. doi:10.1016/j.coal.2012.02.012

Pan, G., 1983, The origins and pioneers of angiosperms inYanliao area, North China: Chinese Science Bulletin, v. 24,p. 1520 p.In Chinese

Peng, X.D., Xu, Z.Y., and Liu, Z.H., 2003, Revision of the Middleand Upper Jurassic Daqingshan Formation in Daqingshanarea, Inner Mongolia: Jouranal of Stratigraphy, v. 27, no. 1,p. 66–70. In Chinese with English abstract.

Petersen, H.I., 1993, Petrographic facies analysis of Lower andMiddle Jurassic coal seams on the island of Bornholm,Denmark: International Journal of Coal Geology, v. 22, p.189–216. doi:10.1016/0166-5162(93)90026-7

Petersen, H.I., and Andsbjerg, J., 1996, Organic facies develop-ment within Middle Jurassic coal sems, Danish CentralGraben, and evidence for relative sea-level control onpeat accumulation in a coastal plain environment:Sedimentary Geology, v. 106, p. 259–277. doi:10.1016/S0037-0738(96)00015-2

Petersen, H.I., and Brekke, T., 2001, Source rock analysis andpetroleum geochemistry of the Trym discovery NorwegianNorth Sea: A Middle Jurassic coal-sourced petroleum sys-tem: Marine and Petroleun Geology, v. 18, p. 889–908.doi:10.1016/S0264-8172(01)00033-2

Qinghai Bureau of Geology and Mineral Resources (QBGMR),1991, Geological Memoirs of Qinghai Province: Beijing,Geological Publishing House, p. 605. In Chinese.

Rajabzadeh, M.A., Ghorbani, Z., and Keshavarzi, B., 2016,Chemistry, mineralogy and distribution of selected trace-elements in the Parvadeh coals, Tabas, Iran: Fuel, v. 174, p.174–224. doi:10.1016/j.fuel.2016.02.004

Ree, P.M., Noto, C.R., Parrish, J.M., and Parrish, J.T., 2004, LateJurassic climates, vegetation, and dinosaur distributions:The Journal of Geology, v. 112, no. 6, p. 643–653.doi:10.1086/424577

Sellwood, B.W., and Valdes, P.J., 2006, Mesozoic climates:General circulation models and the rock record:Sedimentary Geology, v. 190, p. 269–287. doi:10.1016/j.sedgeo.2006.05.013

Sellwood, B.W., and Valdes, P.J., 2008, Jurassic climates:Proceedings of the Geologists’ Association, v. 119, p. 5–17.

Sun, C.L., Dilcher, D., Wang, H.S., Sun, G., and Ge, Y.H., 2009,Czekanowskia from the Jurassic of Inner Mongolia, China:International Journal of Plant Sciences, v. 170, no. 9, p.1183–1194. doi:10.1086/605869

Sze, H.C., 1955, On the botanical character of the Yenchangflora, northern Shensi: Acta Palaeontologica Sinica, v. 3, no.4, p. 245–259. In Chinese with English abstract.

Sze, H.C., 1959, Jurassic plants from Tsaidam, ChinghaiProvince: Acta Palaeontologica Sinica, v. 7, no. 1, p. 1–31.In Chinese with English abstract.

Vakhrameyev, V.A., and Doludenko, M.P., 1977, The Middle–Late Jurassic boundary, an important threshold in thedevelopment of climate and vegetation of the NorthHemisphere: v. 19, no. 6, p. 621–632.

Van Der Voo, R., Hinsbergen, D.J.J.V., Domeire, M., Spakman,W., and Torsvik, T.H., 2015, Latest Jurassic–earliestCretaceous closure of the Mongol–Okhotsk Ocean: A paleo-magnetic and seismological-tomographic analysis:Geological Society of America Bulletin, v. 513, p. 589–606.

Wang, T., Shao, L.Y., Tian, Y., Lu, J., and Wang, W.L., 2012,Sequence stratigraphy of the Jurassic coal measures in

northwestern China: Acta Geologica Sinica, v. 86, no. 3, p.769–778. doi:10.1111/j.1755-6724.2012.00702.x

Wang, Y.D., Mosbrugger, V., and Zhang, H., 2005, Early toMiddle Jurassic vegetation and climatic events in theQaidam Basin, Northwest China: Palaeogeography,Palaeoclimatology, Paleoecology, v. 224, p. 200–216.doi:10.1016/j.palaeo.2005.03.035

Wang, Z.H., Zhao, Y., Zou, H.B., Li, W.P., Liu, X.W., Wu, H., Xu, G.,and Zhang, S.H., 2007, Petrogenesis of the early JurassicNandaling flood basalts in the Yanshan belt, North ChinaCraton: A correlation between magmatic underplating andlithospheric thinning: Lithos, v. 96, no. 3, p. 543–566.doi:10.1016/j.lithos.2006.12.004

Williams, I.S., 1998, U–Th–Pb geochronology by ion microp-robe, in McKibben, M.A., Shanks III, W.C., and Ridley, W.I.,eds, Applications of microanalytical techniques to under-standing mineralizing processes: Littleton, the UnitedStates of America, Society of Economic Geologists, Inc.,Review in Economic Geology, v. 7, p. 1–35.

Wong, W.H., 1927, The Mesozoic orogenic movement in east-ern China: Geological Society of China Bulletin, v. 8, p. 33–44. doi:10.1111/j.1755-6724.1929.mp8001004.x

Wong, W.H., 1929, Crustal movements and igneous activitiesin eastern China since Mesozoic time: Acta GeologicaSinica, v. 6, no. 1, p. 9–37.

Wu, H.Z., and Zhang, X.L., 1983, Palynologcial assemblagefrom the upper coal-bearing member of the BeipiaoFormation of Liaoning: Acta Palaeontologica Sinica, v. 22,no. 5, p. 564–572. In Chinese with English abstract.

Wu, S.Q., and Zhou, H.Z., 1986, Early Liassic plants from EastTianshan Mountain: Acta Palaeontologica Sinica, v. 25, no.6, p. 636–647. In Chinese with English abstract.

Xiao, W.J., Windley, B., Hao, J., and Zhai, M.G., 2003, Accretionleading to collision and the Permian Solonker suture, InnerMongolia, China: Termination of the central Asian orogenicbelt: Tectonics, v. 22, no. 6, p. 1069. doi:10.1029/2002TC001484

Xu, G., Zhao, Y., Wu, H., and Zhang, S.H., 2005, Late Triassic–Middle Jurassic stratigraphic succession in the NiuyingziBasin, Lingyuan County, western Liaoning and the correla-tion of regional stratigraphic sequences in the Yanliaoregion: Acta Geoscientica Sinica, v. 26, no. 4, p. 299–308.In Chinese with English abstract.

Xu, W.L., Pei, F.P., Wang, F., Meng, E., Ji, W.Q., Yang, D.B., andWang, W., 2013, Spatial–Temporal relationships ofMesozoic volcanic rocks in NE China: Constraints on tec-tonic overprinting and transformations between multipletectonic regimes: Journal of Asian Earth Sciences, v. 74, p.167–193. doi:10.1016/j.jseaes.2013.04.003

Yang, P., Xie, Z.K., Yuan, X.J., Zhu, S.J., and Yi, D.B., 2006,Palaeoecological characteristics and its palaeogeographicsignificance of the Jurassic in northern margin of QaidamBasin: Journal of Paleogeography, v. 8, no. 2, p. 165–173. InChinese with English abstract.

Yang, W., and Li, S., 2008, Geochronology and geochemistry ofthe Mesozoic volcanic rocks in western Liaoning:Implications for lithospheric thinning of the North ChinaCraton: Lithos? v. 102, no. 1, p. 88–117. doi:10.1016/j.lithos.2007.09.018

Yang, Y.T., Guo, Z.X., and Luo, Y.J., 2017, Middle–Late Jurassictectonostratigraphic evolution of Central Asia, implicationsfor the collision of the Karakoram–Lhasa Block with Asia:

970 H.-L. GAO ET AL.

Earth Science Reviews, v. 166, p. 83–110. doi:10.1016/j.earscirev.2017.01.005

Yu, H.F., Zhang, Z.C., Shuai, G.W., Chen, Y., and Tang, W.H.,2016, SHRIMP and LA–ICP–MS U–Pb ages and geologicalsignificance of the volcanic rocks in the TiaojishanFormation in Ming Tombs area–Western Hills, Beijing:Geological Review, v. 62, no. 4, p. 807–826. In Chinesewith English abstract.

Zhai, M.G., Meng, Q.R., Liu, J.M., Hou, Q.L., Hu, S.B., Li, Z.,Zhang, H.F., Liu, W., Shao, J.A., and Zhu, R.X., 2004,Geological features of Mesozoic tectonic regime inversionin eastern North China and implication for geodynamics:Earth Science Frontiers, v. 11, no. 3, p. 285–297. In Chinesewith English abstract.

Zhang, L.J., 1983, On the age of Badaowan Formation innorthern Xinjiang: Scientia Sinica, v. 26, no. 7, p. 774–784.

Zhang, L.S., Yang, S.C., Fan, H.P., Zhang, S.S., Xie, M.Z., Tang, J.X., Sun, Y.M., and Shang, H.T., 2016, The correspondingrelation between Jurassic stratigraphic classification ofnorth Hebei and the stratigraphic chart of Chia:Geological Review, v. 62, no. 4, p. 840–848. In Chinesewith English abstract.

Zhang, W.P., and Li, Y.A., 1990, Sporopollen assemblage ofAhe, Yengisr and Kezilenur formations in Beicheng County,Xinjiang: Xinjiang Geology, v. 8, no. 3, p. 256–271. InChinese with English abstract.

Zhang, Y.F., and Jiang, J.W., 2010, Paleoclimate significance of theMiddle Jurassic flora in the Western Hills of Beijing: Geology inChina, v. 37, no. 2, p. 515–524. In Chinese with English abstract.

Zhang, Y.Q., Chen, H.Y., Wei, W.T., Chen, C., Liu, Y.L., Zhang, L.G., and Zhu, Z.P., 2014, The tuffs from the JiulongshanFormation in the Chengde Basin, northern Hebei: LA–ICP–MS zircon U–Pb age dating and its geological implications:

Sedimentary Geology and Tethyan Geology, v. 34, no. 3, p.88–95. In Chinese with English abstract.

Zhao, J.F., 2007, Restoration of the primary Ordos Basin inZhiluo–Anding period [PhD thesis]: Northwest University,Xi’an, China, 135 p. In Chinese with English abstract.

Zhao, Y., 1990, The Mesozoic orogenies and tectonic evolutionof the Yanshan area: Geological Review, v. 36, no. 1, p. 1–13. In Chinese with English abstract.

Zhao, Y., Cui, S.Q., Guo, T., and Xu, G., 2002, Evolution of aJurassic basin of the Western Hills, Beijing, North China andits tectonic implications: Geological Bulletin of China, v. 21,no. 4–5, p. 211–217. In Chinese with English abstract.

Zhao, Y., Song, B., Zhang, S.H., and Liu, J., 2006,Geochronology of the inherited zircons from JurassicNandaling basalt of the Western Hills of Beijing, NorthChina: Its implications: Geoscience Frontiers, v. 02, p. 184–190.In Chinese with English abstract.

Zhao, Y., Xu, G., Zhang, S.H., Yang, Z.Y., Zhang, Y.Q., and Hu, J.M., 2004a, Yanshanian movement and conversion of tec-tonic regimes in East Asia: Earth Science Frontiers, v. 11, no.3, p. 319–328. In Chinese with English abstract.

Zhao, Y., Yang, Z.Y., and Ma, X.H., 1994, Geotectonic transitionfrom Paleo-Asian system and Paleo-Tethyan system toPaleo-Pacific active continental margin in eastern Asia:Scientia Geologica Sinica, v. 29, no. 2, p. 105–118. InChinese with English abstract.

Zhao, Y., Zhang, S.H., Xu, G., Yang, Z.Y., and Hu, J.M., 2004b,The Jurassic major tectonic events of the Yanshanian intra-plate deformation belt: Geological Bulletin of China, v. 23,no. 9–10, p. 854–863. In Chinese with English abstract.

Zheng, S.L., and Zhang, W., 1990, Basic characteristics ofTianshifu Flora: Liaoning Geology, v. 4, p. 322–334.InChinese with English abstract.

INTERNATIONAL GEOLOGY REVIEW 971