Introduction

The Jiaodong Peninsula is in the southeastern margin of the North China Craton and to the east of the NNE-trending Tan-Lu Fault (Fig. 1). The dominant structures in the Jiaodong area are NNE-trending faults, which are subsidiary to the regional Tan-Lu Fault (Fig. 2; Goldfarb et al. 2001; Zhou et al. 2002; Qiu et al. 2002; Fan et al. 2003).

Fig. 1
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Simplified geological map showing the tectonic subdivision of the North China Craton (modified from Zhao et al. 2005). Rectangle shows location of the study area in Fig. 2

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Fig. 2
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Simplified geological map of the Jiaodong Peninsula showing the main tectonic units, first-order fault zones, and gold deposits (modified from Wang et al. 1998)

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The Tan-Lu Fault is considered to be of key significance to the tectonic evolution of eastern China (Leech and Webb 2013). In addition, gold deposits are developed along its subsidiary NNE-trending faults (Fig. 2; Deng et al. 2003, 2006, 2015). Examples include the Sanshandao and Cangshang deposits along the Sanshandao Fault; the Jiaojia, Xincheng, and Wang’ershan deposits along the Jiaojia Fault; the Zhaoyuan and Dayingezhuang deposits along the Zhaoping Fault; and the Jinniushan and Denggezhuang deposits along the Jinniushan Fault. The NNE-trending auriferous faults have a total gold reserve of >3000 t (Goldfarb et al. 2014), of which the Jiaojia Fault (JJF) hosts a gold reserve of ∼1200 t at grades of 1.01 to 26.44 g/t Au (Song et al. 2014).

Gold deposits of the Jiaodong Peninsula are divided into quartz vein-style “Linglong-type” and disseminated- and stockwork-style “Jiaojia-type” gold mineralization (Qiu et al. 2002; Deng et al. 2003; Yang et al. 2014; Wang et al. 2015). Gold deposits along the JJF are representatives of the disseminated- and stockwork-style “Jiaojia-type” of mineralization (Wang 2010). These deposits have been interpreted as orogenic deposits (Groves et al. 1998; Goldfarb et al. 2001, 2005, 2007; Kerrich et al. 2000; Qiu et al. 2002; Zhou and Lu 2000; Goldfarb et al. 2014; De Boorder 2015), magmatic–hydrothermal gold deposits (Zhai et al. 2011), or a unique class of “Jiaodong-type” gold deposits associated with intraplate tectonics (Zhai et al. 2004; Zhai and Santosh 2013; Song et al. 2014; Li et al. 2015).

Despite of the significant gold reserves hosted by the JJF, the dynamic mechanism and tectonic evolution that ultimately led to gold deposition is poorly understood, partly due to the limited data from the structure. Previous research in this area has focused on granites and gold deposits (Deng et al. 2003, 2006). However, no detailed studies have focused on the tectonic evolution of the fault and its relationship with the gold mineralization of the JJF. In this work, we present new zircon U–Pb, illite K–Ar, and apatite fission track thermochronological data along the JJF, in order to enhance our understanding of the tectonic evolution of this region and the relationship between the timing of tectonic movements of the fault and the gold mineralizations within the Jiaodong Peninsula.

Geological setting and structural characteristics

The Jiaodong Peninsula is divided by the Wulian–Qingdao–Yantai Sulu Suture into the Jiaobei Terrane in the north and the Sulu Terrane in the south (Fig. 2). The Precambrian sequences of the Jiaobei Terrane consist of the Archaean Jiaodong Group, the Paleoproterozoic Fenzishan and Jingshan Groups, and the Neoproterozoic Penglai Group (Zhou and Lu 2000). The Jiaodong Group consists of granulite, amphibolite, gneiss, and schist. The Jingshan Group consists of marble, biotite–plagioclase gneiss, and amphibolite, and the Fenzishan Group consists of marble, schist, gneiss, and amphibolite. The Penglai Group, which unconformably overlies both the Jingshan and Fenzishan Groups, consists of limestone, shale, and marble.

Mesozoic granitic bodies comprise >40 % of the exposed rocks in the Jiaodong Peninsula (Qiu et al. 2002) and are subdivided into (i) the Jiazishan and Chashan Triassic plutons, (ii) the Linglong and Kunyushan Jurassic plutons, and (iii) the Guojialing and the Shangzhuang Cretaceous plutons (Fig. 2). Similar Cretaceous felsic and mafic igneous rocks are present in the area of the North China Craton (NCC) with an interpreted crustal and mantle source and a transition from enriched mantle to depleted mantle (Guo et al. 2005; Liu et al. 2014). This transition has been associated with lithosphere thinning in this part of the NCC during the Mesozoic (Guo et al. 2005; Liu et al. 2014).

Regional faults within the Jiaodong Peninsula predominantly trend NNE and, to a lesser extent, to the NW. The Huangxian–Yexian arc fault zone (Huangye Fault) is one of the most important faults zones in the peninsula, and it can be divided into (1) a northern segment located in Huang County, which is characterized by ENE-trending faults dipping 30–45° to the north; and (2) a southern segment located in Ye County, which is characterized by NNE-trending faults dipping 29–43° to the NW. The JJF is part of the southern segment of the Huangye Fault and is about 30 km long and 100–400 m wide. The JJF is characterized by a single main fault plane, marked by a gray-colored fault gouge zone that is 50–200 mm wide, which is present throughout the area. Two types of deformations with the same attitudes have affected the fault. One is ductile shear deformation, in which porphyroclasts, schistosity, augen, rotating morphology, and domino structures are well developed (Fig. 3). The other is a large-scale deformation resulting in the formation of cataclastic rocks (Wang 2010).

Fig. 3
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The Jiaojia Fault and its structural controls on gold deposits in the Jiaojia ore field (Wang 2010)

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Jiaojia Fault and its structural controls on gold deposits

The most prominent fault in the Jiaojia mineral field is the JJF that controls the spatial distribution of gold mineralization (Fig. 3), which includes the Sizhang, Matang, Jiaojia, Wangershan, Dongji, Longbu, Hedong, Hexi, Fujia, Xincheng, and Shangzhuang deposits (Fig. 3). These deposits occur in the footwall of the JJF and the Linglong Granite as the hanging wall. Underlying the JJF include the Linglong Granite, Guojialing Granodiorite, and the Jiaodong Group.

The gold deposits along the JJF consist of disseminated- and stockwork-style mineralization. The disseminated type of mineralization extends for ∼50 m below and parallel with the fault, whereas the stockwork-type mineralization extends from tens up to hundreds of meters from the fault (Fig. 4). The disseminated-type mineralization is hosted by pyritized, sericitized, and silicified granite (Fig. 5c). Alteration is characterized by sericite, quartz, and K-feldspar. The stockwork-type mineralization is hosted by potassic-altered and silicified granite (Fig. 5b, d, e).

Fig. 4
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Geological features of the Jiaojia Fault showing a the geological map of the Xincheng deposit and b geological section a–b in the #183 exploration line of the Xincheng deposit. The boundaries of the Jiaojia Fault represent extent of damage from large-scale brittle deformation (modified from Wang et al. 2015)

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Fig. 5
figure 5

Macroscopic features of samples selected for ore mineralogy and paragenetic studies of a Shangzhuang granodiorite, b K alteration of a granitic rock, c disseminated-type ore in quartz–sericite–pyrite-altered rocks, d stockwork-type ore in a silicified granitic rock, e stockwork-type ore in K-altered granitic rock, and f disseminated-type ore intersected by galena vein (modified from Wang et al. 2015)

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Major minerals in the gold deposits along the JJF include native gold, electrum, native silver, iron-bearing native silver, acanthite, pyrite, sphalerite, and galena (Fig. 5f). Gangue minerals include quartz, sericite, feldspar, calcite, barite, and chlorite. The gold-bearing sulfides are pyrite, chalcopyrite, sphalerite, and galena, all of which are hosted by quartz veins.

Four mineral associations have been identified in the deposits, which are as follows: (1) quartz–K-feldspar–pyrite marking the earliest stage of mineralization; (2) quartz–pyrite–gold being the most important auriferous stage during which large amounts of pyrite, quartz, and native gold were precipitated; (3) quartz–base metal sulfides(–gold) marks a minor gold mineralization period with the precipitation of large amounts of sulfide minerals such as pyrite, galena, sphalerite, chalcopyrite, and arsenopyrite; and (4) quartz–calcite–pyrite hosted by quartz, calcite, and siderite forming veins in late fractures.

Methods and analytical procedures

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U–Pb dating

Granodiorite samples SZ-02 and XC480-03 are from the porphyritic Shangzhuang granite (Figs. 3 and 5a). The samples consist of K-feldspar (∼30 vol%), plagioclase (∼40 vol%), quartz (∼25 vol%), biotite and amphibole (∼5 vol%), and accessory titanite, apatite, zircon, and magnetite.

Zircon LA-ICP-MS U–Pb analysis was conducted at the Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing, China. The analysis involves ablation of zircon with a NUP 213 Excimer laser using a spot diameter of 25 μm, with constant 2.5 J/cm2 energy density, and a repetition rate of 10 Hz. Detailed operating conditions for the laser ablation system and the LA-ICP-MS instrument and the data reduction are described by Hou et al. (2009). Preferred U–Th–Pb isotopic ratios used for GJ1 are from Jackson et al. (2004). Uncertainty of preferred values for the external standard GJ1 was propagated to the ultimate results of the samples. In all analyzed zircon grains, the common Pb correction was not necessary due to the low signal of common 204Pb and high 206Pb/204Pb. Concentrations of U, Th, and Pb were calibrated using zircon M127 (Nasdala et al. 2008). Concordia diagrams and weighted mean calculations were made using Isoplot/Ex_ver3. The zircon Plesovice is dated as unknown samples and yielded weighted mean 206Pb/238U age of 337 ± 2 Ma (2σ, n = 12), which is in good agreement with the recommended 206Pb/238U age of 337.13 ± 0.37 Ma (2σ) (Slama et al. 2008) (Table 1).

Table 1 LA-ICP-MS zircon U–Pb analytical results in the Xincheng deposit
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Apatite fission track method

In order to reconstruct the thermal history of the JJF, four disseminated-style samples (SC-01, XC175-02, XC205-04, and XC480-03) and four stockwork-style samples (XC480-07, XC580-18, XC600-07, and XC600-08) of ore from the Xincheng deposit were analyzed for apatite fission track thermochronology (Table 2).

Table 2 Apatite fission track analytical data of the Xincheng gold deposit samples
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Apatite was separated by standard magnetic and heavy liquid techniques. A uranium free muscovite sheet was attached, as an external detector, to each grain mount, and neutron influence was determined using the SRM 962 uranium dosimeter glass. The apatite was etched in 6.6 % HNO3 for 30 s at 25 °C. Etched spontaneous tracks in apatites were counted using Nikon Eclipse® E600 microscope with ×100 dry objectives and ×10 eyepieces. Fission track ages and length data were modeled following the method of Ketcham et al. (1999). Apatite composition was monitored by a combination of etch pit dimensions and absolute measurement by electron microprobe analysis using a JEOL electron microprobe, with an accelerating voltage of 15 kV, a beam current of 29 nA, and a 20-mA defocused electron beam. Apatite fission track dates were calibrated by the zeta-age calibration approach of Hurford and Green (1983) and are reported as central ages with ±2σ errors (95 % confidence interval). We used the χ 2 test to quantify age homogeneity; when P (χ 2) > 5 %, fission track samples contain a single age population (Galbraith 1981). For samples with P (χ 2) < 5 %, we used binomial peak fitting to decompose the observed age distribution into best-fitting grain age components.

K–Ar dating

Fault gouge samples (XC480-01 and XC600-03) from the JJF at the Xincheng deposit (Fig. 6b, d) were analyzed for illite K–Ar dating in order to constrain the timing of movements along the fault (Table 3). These samples consist of quartz, illite, illite/smectite, kaolinite, calcite, and pyrite. Results of X-ray diffraction analyses confirm that the clay mineral component along the JJF is dominantly illite/smectite (∼73 %) with small amounts of saponite (∼24 %) and minor amounts of kaolinite (∼3 %) in the <0.15-μm fraction. The clay mineral component in the 0.15–0.3-μm fraction is, again, dominantly illite/smectite (∼75 %) with small amounts of saponite (∼20 %) and minor amounts of kaolinite (5 %). Similarly, major amounts of illite/smectite were found in the <0.3-μm fraction and minor amounts in the <2-μm fractions.

Fig. 6
figure 6

Macroscopic features of the Jiaojia Fault: a augen structure of quartz, b domino structure, c quartz cut by dextral shear, and d schistosity zone

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Table 3 K–Ar dating data for illites from the Jiaojia Fault
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Illite separation was carried out using high-speed and super high-speed centrifugal separation techniques (Hamilton et al. 1989). The K–Ar dating technique follows the methods described in detail by Faure (1986). The argon isotopic composition of the JJF gouge samples was measured with an MM5400 Mass Spectrometer at the Center of Experiment and Research, China Research Institute of Petroleum Exploration and Development, Beijing. Illite samples were melted at 1500 °C and a quantitative diluent for 38Ar was added. Subsequently, (40Ar/38Ar)m, (38Ar/36Ar)m, radioactive 40Ar, and potassium contents were determined. The analytical error for the K/Ar age calculations is given at a 95 % confidence level (2σ).

Results

U–Pb dating

Zircons from the Shangzhuang granite are colorless or buff to transparent, euhedral to subhedral, and elongate to stubby grains. They display oscillatory zoning typical of magmatic grains in cathodoluminescence (CL) images (Fig. 7). The analytical results of the U–Pb dating are listed in Table 1. Data of Th/U ratios from the granodiorite samples vary between 0.24 and 0.83 also suggesting a magmatic origin (Table 1). Thus, the U–Pb ages of the zircons are interpreted as the crystallization ages of the rocks. The U–Pb concordia diagrams for the zircon analyses are shown in Fig. 7. Eighteen of 20 zircon analyses from sample SZ-02 form a tight cluster, with a weighted mean 206Pb/238U age of 132 ± 1 Ma (2σ, mean square of weighted deviation (MSWD) = 0.9; Fig. 7a). Nineteen of 20 analyses of zircons from sample XC480-03 also form a tight cluster, close to concordia, with a weighted mean 206Pb/238U age of 127 ± 1 Ma (2σ, MSWD = 0.6; Fig. 7b).

Fig. 7
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Zircon U–Pb concordia plots and calculated weighted mean 206Pb/238U dates for Shangzhuang granite from the Xincheng gold deposit

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Fission track dating

The data for ore samples with P (χ 2) > 5 % are characteristic of normal single grain age distribution (Fig. 8), yielding central ages between 55 and 21 Ma. The track length distribution is unimodal positively skewed and relatively narrow (Fig. 9). The mean track length is short (12.3 μm), which is typical of rocks with repetitive stay within or slow cooling through the apatite partial annealing zone (∼60–120 °C; Tagami and Shimada 1996).

Fig. 8
figure 8

Radial plots of single grain apatite ages with extra Poissonian variations. The Y-axis indicates the standardized error on single grain ages, and the X-axis depicts the percentage of relative error (inversely related to precision) of each grain age. Single grain ages are read off the axis (plotted on a logarithmic scale) by drawing a line through the single grain point from the intercept to the radial scale

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Fig. 9
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Histogram of the apatite fission track ages

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Illite K–Ar dating

Sample XC480-01 yielded illite K–Ar ages of 83 ± 2 and 68 ± 2 Ma. Sample XC600-03 yielded illite K–Ar ages of 85 ± 1 and 82 ± 2 Ma. The radiogenic 40Ar content of these samples ranges from 68.0 to 90.4 %, which indicates that the results are reliable. The potassium contents range from 5.15 % (<0.15 μm) to 5.72 % (0.3–0.15 μm). The related nearly identical K–Ar data for these size fractions suggest similar illite formation ages, because other K-rich mineral contaminants could not be detected by XRD investigations. Another K-feldspar has been identified in the 2–6-μm fractions in some samples, but none has been found in the <0.15-μm fraction (Table 3). Illite is of authigenic origin and, therefore, represents a negligible source of error for the age interpretations.

Discussion

Tectonic evolution of the Jiaojia Fault

Jurassic initiation and sinistral movement

The Jurassic (ca. 160–150 Ma) Linglong Granite bordering the JJF (Figs. 2 and 3) has been interpreted as having been derived by partial melting of a tectonically thickened crust (Wang et al. 1998; Qiu et al. 2002; Hu et al. 2004; Guo et al. 2005). Their ages have been determined by SHRIMP/LA–ICP–MS U–Pb zircon method to be at 160 ± 3 to 153 ± 4 Ma (Miao et al. 1997; Wang et al. 1998), 157 ± 2 Ma (Zhang et al. 2010), 159 ± 1 Ma (Yang et al. 2012), and 160 ± 3 to 157 ± 3 Ma (Ma et al. 2013).

Various researchers have attempted to explain the tectonic setting for the Jurassic magmatism in the Jiaodong Peninsula, but a consensus has not been reached (Zhou and Lu 2000; Wang et al. 2013). However, most researchers consider that the collision between the North China and Yangtze cratons commenced in the latest Paleozoic to Early Mesozoic and ended by the Early Jurassic (ca. 213–188 Ma) (Okay and Sengor 1992; Yin and Nie 1993; Li 1994). Since the Middle Jurassic, the Paleo-Pacific Plate subducted beneath the NCC resulting in adakite-like magmatism in an active compressive continental margin (Wu et al. 2005; Wang et al. 2014c), such as the Linglong Granite in the Shandong Peninsula (Wu et al. 2005). Therefore, we interpret the U–Pb results in the context of the convergence between the Paleo-Pacific oceanic plate and the Asian continent.

Previous researchers have suggested that a sinistral shear on the NE striking faults under a NNW–SSE compression, while WSW–ENE tension may have taken place during the Early–Middle Jurassic (Xu et al. 1987; Gilder et al. 1999; Schmid et al. 1999; Mercier et al. 2007). This resulted in sinistral transform faults in the Jiaodong Peninsula (Fig. 10a). Zhu et al. (2004) have reported that 40Ar/39Ar plateau ages of muscovite samples of mylonite from a sinistral ductile shear zone are ca. 193–189 Ma, suggesting that a sinistral strike–slip movement has taken place in the Early Jurassic along the Tan-Lu Fault. In addition, we observed domino-type structures along the JJF (Fig. 6b), which are indicative of sinistral shearing during the Jurassic. As mentioned earlier, during the Early–Middle Jurassic and possibly the Late Jurassic, the NE-trending faults have acted as sinistral transform faults (Fig. 10a).

Fig. 10
figure 10

Evolution of regional stress field and kinematic model of the middle Tan-Lu Fault Zone and NNE-trending structures in the Zhaoyuan–Laizhou area. The drifting history of the Pacific Plate is based on Koppers et al. (2001) and Sun et al. (2007). Evolution of the middle Tan-Lu Fault Zone and Jiaojia Fault after Chen and Dickinson (1986), Xu et al. (1987), Yan and Ma (1992), Northrup et al. (1995), Wan and Zhu (1996), Allen et al. (1997), Faure et al. (1999), Gilder et al. (1999), Schmid et al. (1999), Grimmer et al. (2002), Zhang et al. (2003a, b), Zhu et al. (2004), Sharp and Clague (2006), Ren et al. (2007), Mercier et al. (2007), Sun et al. (2007), Deng et al. (2009a), Wang et al. (2009), Charles et al. (2013), Gu et al. (2013), and Huang et al. (2013)

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Early Cretaceous switch between normal and sinistral strike–slip faulting

The Cretaceous magmatism is represented by the emplacement age of the Shangzhuang granite bordering the JJF (Fig. 3), with U–Pb zircon ages of 130 ± 3 to 126 ± 2 and 129 ± 1 Ma (Hu et al. 1987; Xu et al. 1989; Li and Yang 1993; Miao et al. 1997; Wang et al. 1998, 2014d; Yang and Zhou 2001; Yang et al. 2012). Our zircon LA-ICP-MS U–Pb dating of the granodiorite from the JJF yield interpreted emplacement ages of ca. 132 and 127 Ma, consistent with previous dating (Fig. 7). The granodiorite is interpreted to be related to the subduction of the Paleo-Pacific Plate beneath the NCC, which was possibly associated with slab break-off and roll back or lithospheric delamination of the NCC (Xu et al. 2009; Yang et al. 2012; Zhang et al. 2014; Wilde et al. 2003; Zhai and Santosh 2013). This magma emplacement was aided by the development of the NE-trending faults (Guo et al. 2014).

The ages of the igneous rocks constrain on the age of the NNE-trending normal faults in the Jiaodong Peninsula that resulted from a NW–SE tension and a NE–SW compression lasting from 135 to 120 Ma (Fig. 10b; Xu and Zhu 1994; Zhang et al. 2003a, b; Zhu et al. 2004; Ren et al. 2007; Sun et al. 2007; Deng et al. 2009a). Charles et al. (2011) and Yang et al. (2014) report that the NNE-trending Zhaoping Fault, which hosts the Zhaoyuan and Dayingezhuang gold deposits, is a detachment fault related to major extensional tectonics. This was followed by sinistral strike–slip faulting associated compression orientated NW–SE and NE–SW orientated tension at ca. 120–110 Ma (Fig. 10c; Sun et al. 2007; Mercier et al. 2007). This was followed at ca. 110 Ma with a change in the strain field with normal faulting related to ENE–SWW compression and a NNW–SSE tension (Zhu et al. 2004; Sun et al. 2007; Mercier et al. 2007). The volcanic rocks in the Laiyang Basin to the north of the Sulu Belt were erupted at ca. 110–105 Ma during that period (Fig. 10d; Qiu et al. 2001b; Guo et al. 2005).

Late Cretaceous–Paleocene normal faulting

Previous authors have attempted to explain the formation, age, and dynamic characteristics of the normal Tan-Lu Fault and its subsidiary NNE-trending structures during the Late Cretaceous–Paleocene in the Jiaodong Peninsula (Wan and Zhu 1996; Faure et al. 1999; Grimmer et al. 2002; Zhu et al. 2004; Mercier et al. 2007; Deng et al. 2009a, b). Wan and Zhu (1996) and Wang et al. (2009) suggest that the fault was active during the Late Cretaceous which was a normal fault with minor sinistral strike–slip movement. As the fault is bordered by a half graben filled with Late Cretaceous to Paleocene sediments, the extensional tectonics related to the normal faulting is regarded as being Late Cretaceous–Paleocene in age (Xu 1993; Zhu et al. 2000). Our illite K–Ar ages of 86 ± 1 and 68 ± 2 Ma along the JJF correspond to this period of extensional faulting along the NNE-trending structures in the peninsula. The subduction direction of the Paleo-Pacific Plate changed again by ∼75° from NEE–SWW to NW–SE, which resulted in the change from ENE–WSW compression and NNW–SSE tension during the late Early Cretaceous to NNE–SSW compression and WNW–ESE tension during the Late Cretaceous to Paleocene (Sun et al. 2007). This change happened after 94 ± 5 Ma, based on the K/Ar illite isotopic data of fault gouge in a northern segment of the Tan-Lu Fault Zone (Koppers et al. 2001; Wang et al. 2009). This interpretation is supported by the change from a late Early Cretaceous NW–SE compression in the Yi–Shu Rift to a Late Cretaceous∼N–S tension in the Jiaolai Graben during 100–90 Ma (Fig. 10e; Zhang et al. 2003a, b; Wang et al. 2009).

Eocene–Oligocene dextral movement and normal faulting

The variable apatite fission track age, the track length distribution, and thermal models suggest that the JJF experienced two major cooling stages caused by exhumation (Fig. 11). These stages relate to (1) a slow exhumation/cooling and uplift in response to a small magnitude of initial extensional deformation during ca. 55 Ma or earlier and (2) a rapid exhumation/cooling and uplift in response to a large magnitude of accelerated extensional deformation initiated at ca. 25 Ma.

Fig. 11
figure 11

Time–temperature histories of samples from the Jiaojia Fault calculated by inverse modeling observed apatite fission track parameters, based on the annealing model of Ketcham et al. (1999). The X- and Y-coordinate reflect the fission track age (Ma) and the temperature (°C), respectively. Shown at the bottom right of each panel is the sample number, measured and model predicted track length, measured and modeled pooled age, and Kolmogorov–Smirnov test, which is used to determine similarity between the measured and predicted apatite fission track age and length parameters. Field between dot lines is the acceptable result predicted by the model, the dashed line space is the goodness-of-fit result, and the solid line is the best-fit result

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Our apatite fission track data analysis and thermal modeling of representative samples dated at ca. 55 Ma corresponds to this period of dextral movement and normal faulting along the NNE-trending structures in the Jiaodong Peninsula. Along the JJF, we observed quartz veins cut by dextral shear in quartz–sericite–pyrite-altered rocks (Fig. 6c). Formation of Eocene rift basins in the Jiaodong Peninsula has been documented at ca. 55 Ma during NW–SE dextral transtension (Fig. 10f; Yan and Ma 1992; Allen et al. 1997; Ren et al. 2007; Huang et al. 2013). It is commonly thought that the Eocene strike–slip and normal faults in the Jiaodong Peninsula are the result of extrusion tectonics driven by the subduction of the Pacific Plate underneath the NCC (Chen and Dickinson 1986; Northrup et al. 1995). Others suggest that the intracontinental deformation in the Jiaodong Peninsula can be linked to the far-field effects of the interaction of the Indian subcontinent with the Eurasian continent during 65–55 Ma (Grimmer et al. 2002; Ratschbacher et al. 2003; Deng et al. 2014a, b; Wang et al. 2014a, b). However, the Indo-Asian collision has little effect on lithospheric evolution of the North China Craton (Zheng et al. 2006; Huang et al. 2011). We propose that the Eocene dextral movement along the NNE-trending structures is a consequence of a change in the movement direction of the Paleo-Pacific Plate from NNE–SSW to its present direction of NW–SE (Beck et al. 1995; Sharp and Clague 2006; Sun et al. 2007).

A regional Late Oligocene inversion associated with a regional ca. 25 Ma unconformity at the base of Neogene strata is documented from the East China Sea and the Jianghan, Hehuai, Jiangsu, Bohai, and Songliao basins (Chen et al. 1989; Hu et al. 1987; Allen et al. 1997). Neogene thermal subsidence in the basins was accompanied by minor normal faulting lasting until the present day (Allen et al. 1997; Gilder et al. 1991; Grimmer et al. 2002).

Tectonic transition and large-scale gold mineralization

The determination of the mineralization age for gold deposits along the JJF is critical for the understanding of its relationship to the tectonic evolution of the NNE-trending structures in the Jiaodong Peninsula. K-feldspar separates from the Dongji deposit have an Ar/Ar plateau age of ca. 116 Ma (Li et al. 2003b). Sericite and muscovite separates from the Jiaojia, Xincheng, and Wang’ershan deposits have Ar/Ar plateau ages of ca. 120 to 119 Ma, ca. 121 to 120 Ma, and ca. 121 to 119 Ma, respectively (Li et al. 2003a). Two Rb–Sr ages of ca. 126 ± 6 and 122 ± 7 Ma were obtained by Wang et al. (2015) from pyrite sampled from the Xincheng gold deposit. Previous dating using the Rb–Sr and Ar–Ar techniques on alteration minerals and fluid inclusions in quartz indicate that the timing of the gold mineralization along the NNE-trending structures in the peninsula is between 130 and 110 Ma (Yang et al. 2003; Li et al. 2013; Zhai and Santosh 2013). The Rb–Sr isochron ages of sericite and pyrite from the Linglong gold deposit along the Zhaoyuan Fault are 112 ± 2 and 120 ± 1 to 123 ± 4 Ma (Luo and Wu 1987; Li et al. 2008) and 120 ± 4 to 123 ± 4 Ma (Yang 2000; Yang and Zhou 2001), respectively. The Ar/Ar plateau age for muscovite from the Sanshandao Fault at the Cangshang deposit is ca. 121 Ma (Zhang et al. 2003a, b. These dates show that the age of gold mineralization in this area is between ca. 130 and 110 Ma, which coincides with the Early Cretaceous magmatism and the transition from early Early Cretaceous (145–120 Ma) normal faulting to late Early Cretaceous (120–110 Ma) sinistral strike–slip faulting (Figs. 10b, c and 12a, b).

Fig. 12
figure 12

Summary of geochronological data and tectonic history showing a histogram of the recent high precision dating results from SHRIMP and LA–ICP–MS zircon U–Pb ages, zircon and apatite fission track data, and 40Ar/39Ar ages in the Jiaodong Peninsula; and b the timing of magmatism and thermal events in the Zhaoyuan–Laizhou area (modified from Wang et al. 2015). Major data sources: Hu et al. (1987), Hu et al. (2004), Hu et al. (2007), Chen et al. (1988), Xu et al. (1989), Li and Yang (1993), Miao et al. (1997), Wan and Wang (1997), Zhao et al. (1997), Guan et al. (1998), Wang et al. (1998, 2005), Qiu et al. (2001a, b, 2012), Yang and Zhou (2001), Zhang et al. (2002, 2010), Zhou et al. (2003), Guo et al. (2004, 2005), Li et al. (2006), Ling et al. (2006), Liu et al. (2004, 2008, 2009), Tan et al. (2008), Tang et al. (2004, 2008), Xie et al. (2008), Goss et al. (2010), Yang et al. (2005, 2012), Kuang et al. (2012), Charles et al. (2013), Ma et al. (2013), Yang et al. (2014), and this study. Mean mineral closure temperatures are from Tagami and Shimada (1996), Villa (1998), Yang (2000), and Verdel et al. (2012)

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In addition, based on these dates, the gold mineralization is correlated with extensive lithospheric thinning that took place at ca. 120 Ma in the Jiaodong Peninsula (Deng et al. 2015). This took place in a period when the stress field in eastern China changed from extension to transpression, resulting from the near orthogonal change in the subduction direction of the Paleo-Pacific Plate from NE–SW to NW–SE (Fig. 10b, c; Koppers et al. 2001; Sun et al. 2007). The transitions of the subduction direction synchronized the lithosphere thinning and the change from normal to sinistral movement along NNE-trending faults that host gold deposits (Fig. 10b, c). Thus, the tectonic setting of the gold deposits in JJF is markedly different from those defined for typical orogenic gold deposits at convergent plate margins (Groves et al. 1998). The geodynamic engine of the Jiaodong gold deposits is the lithospheric thinning and structure adjustment induced by Pacific slab subduction, and the gold mineralization in the Jiaodong Peninsula belongs to intraplate metallogeny. Instead, we propose that these deposits constitute a unique class of “Jiaodong-type” gold deposits, as proposed by earlier researchers (Zhai et al. 2004; Zhai and Santosh 2013; Song et al. 2014; Deng et al. 2015; Li et al. 2015).

Conclusions

  1. 1.

    LA-ICP-MS U–Pb zircon ages of ca. 132 ± 1 and 127 ± 1 Ma from granites constrain that the JJF was a normal fault during the Early Cretaceous, corresponding to a period of large-scale lode gold mineralization, extension-related magmatism, and Cretaceous giant igneous events in the Jiaodong area.

  2. 2.

    This sinistral strike–slip faulting of the JJF lasted during ca. 120–110 Ma, which was related to NW–SE compression and NE–SW tension.

  3. 3.

    Illite K–Ar dates of ca. 83 ± 2 to 68 ± 2 Ma constrain the timing of a second normal faulting event along the JJF (with the first being ca. 110 Ma and the last being ca. 55 Ma).

  4. 4.

    Measured apatite fission track ages of between 55 and 21 Ma correspond to a dextral movement along the JJF.

  5. 5.

    Large-scale gold mineralization is related to a transition of NNE-trending structures from early Early Cretaceous normal faulting to late Early Cretaceous sinistral strike–slip faulting, providing important evidence for the tectonic setting of the Jiaodong gold deposits.