Controls on different mineralization styles of the Dongbulage Mo and Taibudai Cu-(Mo) porphyry deposits in the Great Xing’an Range, NE China

Accepted Manuscript Controls on different mineralization styles of the Dongbulage Mo and Taibudai Cu-(Mo) porphyry deposits in the Great Xing’an Range, NE China Yitao Zhou, Yong Lai, Shu Meng, Qihai Shu PII: DOI: Reference:

S1367-9120(18)30034-8 https://doi.org/10.1016/j.jseaes.2018.01.028 JAES 3400

To appear in:

Journal of Asian Earth Sciences

Received Date: Revised Date: Accepted Date:

2 September 2017 27 January 2018 27 January 2018

Please cite this article as: Zhou, Y., Lai, Y., Meng, S., Shu, Q., Controls on different mineralization styles of the Dongbulage Mo and Taibudai Cu-(Mo) porphyry deposits in the Great Xing’an Range, NE China, Journal of Asian Earth Sciences (2018), doi: https://doi.org/10.1016/j.jseaes.2018.01.028

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Controls on different mineralization styles of the Dongbulage Mo and Taibudai Cu-(Mo) porphyry deposits in the Great Xing’an Range, NE China

Yitao Zhou a,b, Yong Lai a,*, Shu Meng a, Qihai Shu a,c a

Key Laboratory of Orogenic Belt and Crustal Evolution, School of Earth and Space

Sciences, Peking University, Beijing 100871, China b

Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton,

Alberta T6G2E3, Canada c

State Key Laboratory of Geological Processes and Mineral Resources, School of Earth

Sciences and Resources, China University of Geosciences, Beijing 100083, China

*

Corresponding author: Yong Lai

School of Earth and Space Sciences, Peking University, 5 Yiheyuan Road, Beijing 100871, China Tel & Fax: +86 10 62755588 E-mail: [email protected]

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Abstract The Dongbulage porphyry Mo-dominant and Taibudai Cu-(Mo) deposits are located in the central–southern Great Xing’an Range, Inner Mongolia, northeastern China, and are associated with granite porphyry and monzogranite intrusions, respectively. Re–Os isotope data for five molybdenite samples from the Dongbulage Mo deposit give a weighted mean model age of 164.3 ± 1.2 Ma, which is in accordance with a zircon U–Pb age of 164.5 ± 1.7 Ma for the host granite porphyry, indicating that the deposit formed at the end of the Middle Jurassic. The zircon U–Pb age of the Taibudai ore-bearing monzogranite is 137.9 ± 1.7 Ma, indicating that the deposit formed in the Early Cretaceous. Whole-rock geochemical data indicate that the Dongbulage granite porphyry and the Taibudai monzogranite are high-K calc-alkaline, and have REE patterned light rare earth elements (LREEs) enriched and heavy rare earth elements (HREEs) depleted. Both plutons show Ba, Nb, and Ti depletions on normalized trace element diagrams, and the Dongbulage granite porphyry shows strongly negative Eu anomalies which are absent in the Taibudai intrusion. The geochemical differences between the two intrusions suggest that the Dongbulage granite porphyry is the result of more advanced fractional crystallization, which led to the formation of a Mo-dominant deposit, whereas the lesser degree of crystal fractionation in the Taibudai monzogranitic magma resulted in the 2

formation of a Cu deposit. The relatively listric-shaped REE patterns of Taibudai rocks suggest more hydrous parental magmas than that of Dongbulage rocks. Therefore, fractional crystallization and magma water content exert a significant control on the styles of mineralization (Mo- versus Cu-dominant) in the central–southern Great Xing’an Range.

Keywords: Porphyry deposit; Petrogenesis; Yanshanian mineralization; Fractional crystallization; Water content; Central–Southern Great Xing’an Range

1. Introduction Porphyry Cu and Mo deposits can be subdivided into Cu-dominant deposit (with minor Mo and Au) and Mo-dominant deposit (with minor Cu) (Berzina et al., 2005; Robb, 2005). The two types of deposit form in markedly different geologic settings and have distinct geological characteristics and mineral assemblages. The formation of ore minerals is strongly influenced by the tectonic setting, the physico-chemical properties and evolution of ore-related magmas, and the characteristics of ore-forming fluids (Halter and Webster, 2004; Webster, 2004; Williams-Jones and Heinrich, 2005). The Great Xing’an Range is part of the northeast China Mo-Cu metallogenic province (Fig. 1), which is one of three metallogenic provinces in Central Asian 3

metallogenic domain (CAMD, Gao et al., 2018). The other two provinces are the Kazakhstan Cu-Au-Mo and the Mongolia Cu-Au, represented by giant Kal’makyr Cu-Au (Cheng et al., 2017) and Oyu Tolgoi Cu-Au deposit (Kirwin et al., 2005), respectively. In the central–southern part of Great Xing’an Range, there are numerous mineral deposits, including porphyry and skarn deposits. In the 21st century, many porphyry Mo-dominated deposits (e.g., Aolunhua, Yangchang, Banlashan, Haisugou, and Shabutai) were found in the region (Wu et al., 2008; Shu et al., 2009, 2014, 2016; Zhang et al., 2009; Zeng et al., 2010, 2011a, 2011b, 2012; Wu et al., 2011a; Shu and Lai, 2017; Zhou et al., 2017), but only a few porphyry Cu deposits have been discovered to date (Fig. 1A). To understand the controlling factors on these mineralization styles, two typical Mo and Cu deposits located in the Great Xing’an Range, the Dongbulage and Taibudai deposits, have been selected in this study (Fig. 1B). The Dongbulage deposit is a recently discovered porphyry Mo deposit in the western part of the central–southern Great Xing’an Range. The deposit is dominated by molybdenite with minor chalcopyrite, which is a typical mineral association of Mo-dominant deposits. The Taibudai deposit is located in the eastern part of the central–southern Great Xing’an Range, and contains mainly chalcopyrite with minor molybdenite, making it a typical Cu–(Mo) deposit. Given that different ages of ore-related intrusions and geochemical characteristics between these two deposits, it is important to reveal the behaviors of metal elements in the evolution of magmas and 4

different enrichment mechanism of Cu and Mo. In this paper, we present a detailed study of the whole-rock major and trace elemental analyses, U–Pb zircon ages, and Re–Os isochron ages of molybdenite. This new dataset is used to provide information about the origin and evolution of the magmas related to the two deposits, and controlling factors on the formation of the two deposits are discussed.

2. Geological setting The central–southern Great Xing’an Range is located in northeastern China and forms part of the Central Asian Orogenic Belt (CAOB). It is bordered by the Songliao Basin to the east, the Hegenshan Fault to the northwest, and the Xilamulun Fault to the south (Wu et al., 2011b; Fig. 1A). In the Paleozoic, the central–southern Great Xing’an Range was part of the Paleo-Asian Ocean (Wu et al., 2011b). Closure of the Paleo-Asian Ocean led to the development of a magmatic arc and thickening of the continental crust. Collision of the Siberian and Tarim–North China Cratons during the latest Paleozoic formed the CAOB (Chen et al., 2007). Widespread magmatism, starting in the Mesozoic, occurred in a NNE-trending belt and was associated with the formation of numerous non-ferrous ore deposits (Shao et al., 2007). Remnants of Ordovician, Silurian, Devonian, and Carboniferous rocks occur locally, overlain by cover rocks of Permian volcanic–sedimentary sequences, and Jurassic and Cretaceous formations. Permian rocks include the mainly lower Permian Qingfengshan 5

Formation, lower Permian Dashizhai Formation, upper Permian Zhesi Formation, and upper Permian Linxi Formation. The Qingfengshan Formation consists mainly of greywacke and tuff with intercalated meta-basalt. The Dashizhai Formation consists of sandstone, siltstone, andesite, and basaltic andesite, and the Zhesi Formation consists of tuffaceous sandstone, siltstone, conglomerate, and volcaniclastic rocks. The Linxi Formation consists of slate and mudstone (BGMRIM, 1991; Shao et al., 2007). Jurassic and Cretaceous rocks include the lower Jurassic Hongqi Formation, the middle Jurassic Wanbao and Xinmin Formation, the upper Jurassic Manketou’ebo, Manitu, and Baiyingaolao Formations, and the lower Cretaceous Meiletu Formation. These units consist mainly of greywacke, siltstone, sandstone, conglomerate, rhyolite, dacite, basalt, andesite, and tuff. Most of the igneous rocks were emplaced during the Late Jurassic to Early Cretaceous, although small volumes of Hercynian and Indosinian intrusions are also present (Wu et al., 2011b). The intrusive rocks in the eastern part of this district are mainly granite, granite porphyry, and granodiorite, while monzogranite and granite occur in the western part. The large-scale late Mesozoic magmatism was associated with Ag, Au, Pb, Zn, Cu, Fe, Mo, Sn and rare earth element (REE) mineralization. Major fold structures are oriented northeast–southwest, and from northwest to southeast include the Daqingmuchang-Baiyinchagan, Huanggang-Ganzhu’ermiao, Taohaiyingzi-Xingfuzhilu, and Haolibao-Yihenuo’erhua folds. Major faults, such as the Xilamulun, Nenjiang, and Hegenshan faults, controlled the locations of Yanshanian 6

intrusions and polymetallic deposits. The numerous deposits are usually distributed along metallogenic belts, of which the Huanggang-Ganzhu’ermiao metallogenic belt is a typical example. Over 300 Sn, W, Pb, Zn, Mo and REE ore bodies have been discovered, including the Huanggang Sn–Fe deposit, the Baiyinnuo’er and Haobugao Zn–Pb deposits, and the Dajing Cu polymetallic deposit (Shu et al., 2013). The Xilamulun Mo metallogenic belt, recognized only within the past two decades (Zeng et al., 2009; Zhang et al., 2009; Shu et al., 2016), contains numerous known deposits and has great potential for future prospecting (Sun et al., 2008).

3. Ore deposit geology 3.1 The Dongbulage Mo deposit The Dongbulage Mo deposit is located in the town of Baiyinhua, Xi Ujimqin Banner, Inner Mongolia, 55 km east of Balaga’ergaole, which is situated on the western slopes of the Great Xing’an Range. It has reserves of 28 Mt of ore containing 0.11% Mo. The stratigraphic sequence consists mainly of the lower Permian Zhesi Formation, upper Jurassic Baiyingaolao Formation, and Quaternary sediments (Fig. 2). The majority of faults are oriented either north-northeast or northeast. However, secondary faults controlled the location of mineralization. Plutonic rocks are mainly Yanshanian in age and include granite porphyry in the center of the deposit and granite in the southwest. The granite porphyry is gray–white in color and displays a typical porphyritic texture. 7

Phenocrysts are 1–5 mm in diameter, comprise ~15% of the rock, and consist mainly of quartz (~8%), K-feldspar (~6%), and plagioclase (~1%) (Fig. 3D). The groundmass is composed of plagioclase (~50%), K-feldspar (~10%), quartz (~30%), and biotite (~5%). The granite is medium-grained, displays an equigranular texture, and consists of quartz (~40%), K-feldspar (~20%), plagioclase (~30%), biotite (3%–5%), and accessory minerals. In the field, we observed that Mo mineralization is developed mainly within or around the granite porphyry, whereas the granite is barren. In the central mining area, ore minerals include primarily molybdenite (Fig. 3G), which occurs mainly in sulfide-bearing stockwork veins (Fig. 3A). Disseminated molybdenite within the granite (Fig. 3B) is subordinate. The gangue minerals are predominantly quartz, K-feldspar, plagioclase, and sericite. In the south, the ore minerals are sphalerite (Fig. 3H), galena (Fig. 3I), and pyrite. Potassic alteration is widespread in the mining area and is overprinted by phyllic alteration that has a close relationship with the Mo mineralization; most molybdenite–quartz veins are surrounded by a zone of phyllic alteration. Carbonate alteration and chloritization are also widespread and represent late-stage hydrothermal alteration (Fig. 3E, F). The youngest calcite veinlets commonly cross-cut the sulfide–quartz veins and coexists with minor fluorite (Fig. 3C).

3.2 The Taibudai Cu–(Mo) deposit 8

The Taibudai Cu–(Mo) deposit is located in the Bayantala district, Bairin Right Banner, Inner Mongolia, ~35 km east of Daban. It has reserves of 2 Mt of ore containing 0.77% Cu. The deposit is situated north of the Xilamulun Fault. The country rock consists of volcaniclastic rocks of the Upper Jurassic Manitu Formation and Manketou’ebo Formation (Fig. 4). Major faults in the mining area include the north-northeast-striking Sandaoyingzi Fault and the northeast-striking Suodalai and Luobuge faults. The Sandaoyingzi Fault, which cuts the Jurassic volcaniclastics in the eastern part of the deposit, appears to have controlled the location of mineralization. Several Yanshanian granites are exposed in the area, including the Sandaoyingzi intrusion that is associated with the mineralization. This intrusion is primarily a light red, equigranular, medium-grained (2–5 mm) monzogranite, consisting of K-feldspar (~15%), plagioclase (~40%), quartz (~35%), biotite (3%–5%), hornblende (~2%), and accessory magnetite, zircon, and titanite. The gangue minerals are predominantly quartz, K-feldspar, pyrite (Fig. 5H), plagioclase, sericite, and calcite. Ore minerals include chalcopyrite, molybdenite (Fig. 5G), sphalerite, and galena (Fig. 5D). The ore minerals occur as disseminated grains and in veins (Fig. 5A, C). In the core of the intrusion, potassic alteration is characterized by K-feldspar–quartz veins and secondary biotite, and is commonly overprinted by phyllic alteration. In the southwestern part of the intrusion, late-stage kaolinite and carbonate alteration are common. 9

On the basis of field and mineralogical evidence, the mineralization can be divided into four stages: (1) the potassic–quartz stage is the main stage of Cu mineralization, and mineralized veins generally consist of quartz, chalcopyrite, pyrite, and molybdenite, with widespread K-feldspar veinlets; (2) the quartz–sericite stage favored Mo mineralization in veins of quartz, molybdenite, pyrite, sericite, and minor chalcopyrite; (3) the polymetallic sulfide–quartz stage involved Pb and Zn mineralization, mainly in the southwestern part of the mining area; and (4) the carbonation stage is characterized by massive calcite–quartz veins.

4. Analytical methods 4.1 Whole-rock major and trace element geochemistry The least-altered (i.e., minimal sulfides and situated away from the core of mineralization) parts of the intrusions associated with the two deposits were sampled for whole-rock geochemical analyses. However, due to widespread potassic alteration in the mining areas, all of the samples are affected to a greater or lesser degree. The whole-rock geochemistry of the Taibudai samples was determined at ALS minerals-ALS Chemex (Guangzhou, China), and that of the Dongbulage samples was determined at the National Research Center of Geoanalysis, Chinese Academy of Geological Sciences (Beijing, China). Major element analyses were performed using X-ray fluorescence spectrometry (PW440). The analytical uncertainties, based on 10

analyses of the Chinese national reference material GSR-1, are better than 5% and the analytical error for oxides is generally less than 2%. The samples for trace element and REE analysis were dissolved in a mixture of HNO3 and HF, and then analyzed using an inductively coupled plasma–mass spectrometer (ICP–MS), as described in detail by Gao et al. (2003). The data quality was assessed by analyzing two Chinese national rock standards (AMH-1 and GBPG-1). Accuracy and precision for most trace elements, including the REEs, are better than 10%.

4.2 U–Pb zircon geochronology Zircons for U–Pb dating were extracted by heavy liquid and conventional magnetic separation, and then purified by handpicking under a binocular microscope. More than 150 zircon grains were mounted in epoxy resin and polished prior to cathodoluminescence (CL) imaging at the SEEL-Lab at Peking University, Beijing, China. U–Pb isotopic data were acquired by excimer laser-ablation (LA; ComPex 102) quadrupole ICP–MS (Agilent 7500ce/cs) at the Key Laboratory of Orogenic Belt and Crustal Evolution, Peking University. Spot analyses were carried out using a laser spot size of 32 μm and a repetition rate of 5 Hz. Zircon ablation and data collection lasted 60 s, following 20 s pre-ablation and 20 s blank background data collection. The sample was carried into the ICP–MS by high purity He and Ar at rates of 0.65 and 0.82 L/min, respectively. Integrations times were 20 ms for 202Hg, 204Pb, and 208Pb; 30 ms for 206Pb; 11

50 ms for 207Pb; and 10 ms for U isotopes and trace elements. Trace elements were calibrated against NIST SRM 610, while U–Pb isotopes and downhole fractionation were corrected with reference to the Plešovice zircon standard (Sláma et al., 2008), and the Harvard zircon 91500 was used as external standard (Wiedenbeck et al., 1995). Raw data were processed with the software Glitter 4.4.2 and error-weighted mean U–Pb ages were calculated using the program Isoplot/Ex 2.0.

4.3 Re–Os isotope analyses The molybdenite samples were purified to 99% by handpicking under a binocular microscope after grinding to powder. Re–Os isotope analyses were performed at the National Research Center of Geoanalysis, Chinese Academy of Geological Sciences using an ICP–MS (TJA X-series). Recoveries for both elements were greater than 90% and total procedural blanks were 0.07 ng for rhenium and 0.01 ng for osmium. Detailed analytical procedures have been described by Du et al. (2004).

5. Analytical results 5.1 Whole-rock major and trace element geochemistry Geochemical data for six granite porphyry and four granite samples from Dongbulage are listed in Table 1. The granite and granite porphyry show similar characteristics. The granite porphyry contains SiO2 = 74.96–77.45 wt.%, Al2O3 = 12

11.66–12.95 wt.%, CaO = 0.56–1.34 wt.%, Na2O+K2O = 7.55 to 8.53 wt.%, and K2O/Na2O = 0.88–5.68. On the SiO2 vs. K2O diagram (Fig. 6A), all except two of the porphyry samples plot within the high-K calc-alkaline field. These rocks are slightly peraluminous, with values for molar Al2O3/(CaO+Na2O+K2O) (A/CNK) of 1.01–1.16. The granite samples contain SiO2 = 72.16–76.23 wt.% and CaO = 0.65–0.96 wt.%, are also classified as calc-alkaline, and have higher Na2O+K2O contents (8.52–9.19 wt.%) than the granite porphyry. The granite samples plot near the metaluminous–peraluminous boundary on the molar Al2O3/(Na2O+K2O) (A/NK) vs. A/CNK diagram (Fig. 6B). On a chondrite-normalized REE diagram, both the granite and granite porphyry are characterized by slight enrichments in LREEs, flat HREEs, and significant negative Eu anomalies (Fig. 7A). On a primitive-mantle-normalized spider diagram, both rock types show positive Pb and Rb anomalies, and negative Sr, Ti, and Ba anomalies (Fig. 7B). Major and trace element geochemical data for nine monzogranite samples from Taibudai are listed in Table 1. The samples contain SiO2 = 67.80–71.30 wt.%, Al2O3 = 13.85–14.85 wt.%, Na2O = 3.40–4.60 wt.%, and K2O = 2.92–4.18 wt.%. All samples plot in the high-K calc-alkaline field on the SiO2 vs. K2O diagram (Fig. 6A). Values for A/CNK show a narrow range from 0.93 to 1.01 and A/NK values range from 1.28 to 1.56, indicating that the Taibudai monzogranite is mainly metaluminous (Fig. 6B). The Taibudai monzogranite shows enrichments in LREEs and flat HREEs (Fig. 7C). The chondrite-normalized REE patterns (Fig. 7C) are listric and lack significant negative Eu 13

anomalies. The primitive-mantle-normalized spider diagram (Fig. 7D) shows positive Pb anomalies and negative Ba, Nb, and Ti anomalies.

5.2 Zircon CL images and U–Pb geochronology We chose granite porphyry (DBLG-9) and granite (DBLG-3) samples from the Dongbulage deposit for U–Pb zircon age dating. The zircon CL images are shown in Fig. 8. Thirty highly transparent and inclusion-free zircons from each sample were analyzed. The zircons range in size from 80 to 250 μm. Most zircons are euhedral–subhedral, exhibit oscillatory growth zoning, and lack inherited cores, consistent with an igneous origin (Pupin, 1980; Hanchar and Hoskin, 2003). The U–Pb data are listed in Table 2. The weighted mean U–Pb age for the granite sample DBLG-3 is 169.1 ± 1.8 Ma (95% confidence) with a mean squared weighted deviation (MSWD) of 0.49 (Fig. 8A). The weighted mean age for the granite porphyry sample DBLG-9 is 164.6 ± 1.7 Ma (95% confidence) with a MSWD of 1.04 (Fig. 8B). Both of the ages are considered to record magmatic crystallization and show that the granite porphyry is slightly younger than the granite. Zircon CL images of the Taibudai monzogranite (TBD-64) are shown in Fig. 8C. Most zircons are euhedral and 100–200 μm long. All of the zircons chosen for analysis are magmatic. U–Pb data are listed in Table 2. The weighted mean age for the Taibudai granite is 137.8 ± 1.2 Ma (95% confidence) with a MSWD of 1.8 (Fig. 8C). The U-Pb 14

age indicates that the Taibudai monzogranite was formed in the early Cretaceous. 5.3 Molybdenite Re–Os isotopes The Re–Os isotopic compositions of five molybdenite samples from the Dongbulage Mo deposit are listed in Table 3. The molybdenite Re–Os model ages of the five samples have a narrow range from 163.6 ± 2.9 to 165.5 ± 2.6 Ma, with a weighted mean age of 164.3 ± 1.2 Ma (MSWD = 0.43). Using the program Isoplot/Ex 2.0, an isochron age of 163.9 ± 1.4 Ma with a MSWD of 0.64 was calculated (Fig. 9). These Re–Os results indicate that Mo mineralization at Dongbulage occurred during the Middle Jurassic. Zhou et al. (2015) reported a Re–Os isochron age of 137.1 ± 1.4 Ma (MSWD = 0.16) and a weighted mean Re–Os model age of 137.6 ± 1.1Ma (MSWD = 0.33) for the Taibudai Cu deposit, indicating that Cu mineralization was coeval with crystallization of the host monzogranite.

6. Discussion 6.1 Petrogenesis of the Dongbulage and Taibudai plutons The Dongbulage pluton is a felsic granite consisting mainly of feldspar and quartz with minor biotite. The silica-rich (>72.16 wt.%) and alkali-rich (>7.85 wt.%) composition, enrichment of LREEs, negative Eu, Ba, Nb, Sr, Eu and Ti anomalies, and positive Pb anomaly suggest that the Dongbulage pluton is highly fractionated (Chappell, 1999; Wu et al., 2003; Wu et al., 2016). In addition, the Dongbulage samples are 15

relatively low in Zr+Nb+Y+Ce and 10,000*Ga/Al, but high in FeO*/MgO and (K2O+Na2O)/CaO. As shown in Fig. 10, the majority of the Dongbulage samples plot in the highly fractionated granite field and outside the A-type field. The Dongbulage samples are mostly peraluminous (A/CNK = 0.99–1.16). However, given that they are highly fractionated, their A/CNK values cannot be used to distinguish whether they are I- or S-type (Chappell, 1999; Clemens et al., 2011). Highly fractioned S-type granites typically have high P2O5 concentrations, while I-type rocks have P2O5 contents of ~0.04 wt.% (Chappell, 1999). Therefore, the low P2O5 of the Dongbulage pluton suggests that it is of I-type affinity. In summary, the Dongbulage pluton is a highly fractioned I-type granite, rather than an A- or S-type granite. The samples of Taibudai monzogranite are silica-rich (>68 wt.%), contain high contents of alkalis (>6.85 wt.%), low Al2O3 and MgO contents, and do not show negative Eu anomalies. They are relatively enriched in Pb, and depleted in Ba, Nb and Ti. The major and trace element characteristics, including A/CNK values of <<1.1 and low concentrations of P2O5 (<0.03 wt.%), of the Taibudai monzogranite are similar to those of I-type granites (King et al., 1997; Chappell, 1999; Chappell and White, 2001; Clemens et al., 2011). On the FeO*/MgO and (K2O+Na2O)/CaO vs. Zr+Nb+Y+Ce diagrams (Fig. 10), all of the Taibudai samples plot in the unfractionated I-, S-, and M-type granite fields. Thus, the Taibudai monzogranite is an unfractionated I-type granite.

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6.2 Timing of mineralization and tectonic implications 6.2.1 Age of the Dongbulage Mo and Taibudai Cu–(Mo) deposits Agreement between the zircon U–Pb age (164.6 ± 1.7 Ma), Re–Os isochron (163.9 ± 1.4 Ma) age, and weighted mean model age (164.3 ± 1.2 Ma) demonstrates that the Dongbulage granite porphyry and Mo mineralization are temporally and genetically related, and the deposit is formed in the middle-late Jurassic. The Dongbulage Mo deposit is situated on the western side of the central–southern Great Xing’an Range, an area in which epithermal and skarn deposits are commonly developed. The Hua’aobaote Pb–Zn, Daolundaba Cu–W–Sn polymetallic, and Yindu Ag–Pb–Zn polymetallic deposits are three examples (Xu et al., 2009). Additionally, in the eastern slope, there are also numerous deposits, such as the Huanggang skarn Fe–Sn, Haobugao and Baiyinnuoer skarn Pb–Zn deposits (Shu et al., 2013). The ages of these deposits range from 130 to 140 Ma, which is considered one of the peak periods of mineralization. For example, the Yindu Ag–Pb–Zn deposit formed at 135 ± 3 Ma (Chang et al., 2010), the Bairendaba–Weilasituo polymetallic deposit formed at 133.4 ± 0.8 Ma (Pan et al., 2009), the Huanggang skarn deposit formed at 135.3 ± 0.9 Ma (Zhou et al., 2010), and the Baiyinnuoer skarn deposit yields an age of 140 Ma (Shu et al., 2013). The age of the Dongbulage deposit (~165 Ma) does not coincide with the 130–140 Ma peak, but it overlaps with the timing of Mo mineralization in central Jilin province, which includes the 168.2 ± 3.2 Ma Daheishan Mo deposit (Wang et al., 2009), the 166.9 ± 6.7 17

Ma Fu’anbao Mo deposit (Li et al., 2009), and the 167.3 ± 2.5 Ma Xingshan Mo deposit (Shu et al., 2014). These data indicate that a widespread Mo mineralization event occurred in northeastern China during the early Yanshanian (Chen et al., 2012; Shu et al., 2016). The LA–ICP–MS U–Pb zircon data indicate that the Taibudai monzogranite formed at 137.8 ± 1.2 Ma. Zhou et al. (2015) reported that the ore formed at 137.1 ± 1.4 Ma, based on Re–Os isotope dating. The agreement of the two ages reveals that the Taibudai monzogranite formed at the same time as the Cu–(Mo) mineralization. The Taibudai deposit is located to the north of the Xilamulun Fault. In the past decade, several Mo deposits have been discovered along this fault. Ore formation along the southern part of the Xilamulun Fault is divided into three periods (258–210, 185–150, and 140–110 Ma; Zhang et al., 2010), According to previous reports of porphyry deposits in this district, the mineralization mainly took place in Early Cretaceous, such as Haisugou porphyry Mo deposit of 136.4 ± 0.8 Ma (Shu et al. 2014), Aolunhua Mo (Cu) deposit of 129.4 ± 3.4 Ma (Shu et al. 2009), and Shabutai Mo deposit of 135.3 ± 2.6 Ma (Shu et al., 2016; Zhou et al., 2017). Shu et al. (2014) summarized the ages of the 17 known deposits in the Xilamulun belt, and found that 10 of the deposits yield ages of 140 to 130 Ma. All the studies described above indicated a peak time for porphyry mineralization at 130-140 Ma.

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6.2.2 Yanshanian Mineralization Mesozoic mineralizations, especially Yanshanian deposits, are widespread in the Great Xing’an Range and occurred mainly at 140–130 and 180–160 Ma. Plutonic rocks in this area are spatially and temporally related to the ore bodies, showing the important role played by magmatic rocks in the mineralization (Mao et al., 2005). The two periods of magmatism were related to closure of the Paleo-Asian Ocean between the late Permian and Early Triassic (Chen et al., 2007). Continental collision during the Permian led to crustal shortening, thickening, and deformation. In the Late Jurassic, the region was under compression due to westward subduction of the Paleo-Pacific Ocean (Zhang et al., 2010). This led to development of an active continental margin and the emplacement of adakitic plutons, which peaked at 180–160 Ma. Closure of the Mongolia Okhotsk Sea and the peak of the Paleo-Pacific Ocean subduction in the Early Cretaceous resulted in a change from a compressional to extensional tectonics in the CAOB (Chen et al., 2009). The formation of metamorphic core complexes and emplacement of A-type granites and mafic dyke swarms in eastern China are indicative of a period of extension (Wu et al., 2005). The switch to extension was accompanied by crustal uplift and a widespread increase in the geothermal gradient, which facilitated the generation of large volumes of granitic magmas, hydrous fluids, and mineralization that peaked at 140–130 Ma (Chen et al., 2007).

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6.3 Key factors controlling Mo and Cu mineralization In porphyry metallogenic systems, different types of deposits host different economic metals (e.g., Cu, Mo, and Au). Previous studies suggest that the key factors controlling mineralization include the evolution of the magma (Candela, 1997; Richards, 2003, 2007) and the ore-forming fluid (Webster, 2004; Williams-Jones and Heinrich, 2005; Heinrich, 2007). The initial ore-forming fluids in a porphyry system are magmatic–hydrothermal fluids, whose character is determined by that of the magma (Halter et al., 2005b; Heinrich, 2005; Stavast et al., 2006; Klemm et al., 2007; Audétat et al., 2008). Thus, the evolution of the ore-forming fluid has a limited influence on minerlization style, although it has an effect on the ratio of Cu to Mo in the deposit (Sun et al., 2012). A fluid inclusion study by Klemm et al. (2008) showed that the Mo/Cu value of early stage fluids in the Questa Mo deposit was ten times that of the Butte Cu-dominant deposit, suggesting that the type of deposit had been determined before the fluid was exsolved from the magma. There are also significant differences between the magmatic evolution of porphyry Cu and Mo deposits. The compositions of magmas that form porphyry Cu–(Mo) deposits are principally modifiedi by partial melting and magma mixing, as documented for the Alumbrera, Butte, El Teniente, and Bingham deposits (Keith et al., 1997; Hattori and Keith, 2001; Rusk et al., 2004, 2008; Halter and Heinrich, 2005a; Klemm et al., 2007; Stern et al., 2011). In contrast, the magmas of porphyry Mo deposits experienced 20

intensive fractional crystallization (e.g., Cave Peak and Questa deposits; Klemm et al., 2008, Audétat et al., 2010). Shu et al. (2014) proposed that the mineralized granites of Mo-dominant deposits were the result of extensive fractional crystallization. Prolonged fractional crystallization favors the formation of Mo-dominant porphyry deposits (Audétat et al., 2008). There are many other factors that affect magma fertility and mineralization processes. For example, Shu et al. (2015) compared mineralized and barren intrusions from several Mo deposits in the Xilamulun belt and suggested that high oxygen fugacity is another key factor in the formation of Mo deposits. Sulfur content also affects metal migration in porphyry deposits (Richards, 2011). The Dongbulage granite porphyry mainly contains quartz and K-feldspar, with scarcely mafic minerals like hornblende and biotite, indicating that this granite is more felsic. While in the monzogranite of the Taibudai pluton, the quartz contents decrease and plagioclase contents increase with the appearance of hornblende and biotite. Therefore, it can be concluded that the Dongbulage magma might have experienced a long-time fractional mineralization, and mafic minerals had crystallized and separated from the residual magma. Compared with the Dongbulage granite porphyry, the Taibudai monzogranite has lower SiO2 and K2O, and higher CaO, MgO, Al2O3 , and Fe2O3T. These differences suggest that the Dongbulage granite porphyry is highly fractionated. Fractional crystallization of hornblende and plagioclase depleted the Dongbulage granite porphyry 21

in Fe2O3T, MgO, and CaO, and in CaO and Al2O3, respectively. The Dongbulage granite porphyry contains high concentrations of Rb, Th, and U. Significant negative Eu anomalies and Sr depletion are consistent with the fractionation of plagioclase for that these two elements are relatively rich in plagioclase. The relatively high Rb/Sr values (Rb/Sr = 1.77–9.89) of the Dongbulage granite porphyry compared with the Taibudai monzogranite (Rb/Sr = 0.25–0.43) also indicate that the former is highly fractioned (Chappell, 1999). To compare with the Dongbulage Mo-dominant deposit and Taibudai Cu (Mo) deposit, a Cu-dominant deposit Tuwu-Yandong is chosen. The Cu-dominant Tuwu-Yandong porphyry deposit is located in the southwestern part of the CAOB and contains mostly Cu with minor Au and negligible Mo (Zhang et al., 2006). On the La/Sm vs. La and Zr/Nb vs. Zr diagrams (Fig. 11), the Dongbulage granite porphyry samples plot along the fractional crystallization line, whereas the Tuwu-Yandong samples plot along the partial melting line (Zhang et al., 2010). The Taibudai monzogranite lies between the Dongbulage and Tuwu-Yandong plutons (Fig. 11). In summary, compared with the Taibudai pluton, the Dongbulage granite porphyry is the result of more advanced fractional crystallization, which we suggest plays an important role in promoting molybdenite mineralization. We have collated geochemical data for six porphyry Cu and Mo deposits from the central–southern Great Xing’an Range (Table 4). These include two Cu–(Mo) deposits 22

(Taibudai and Kulitu), one Mo–(Cu) deposit (Aolunhua), and three Mo-dominant deposits (Dongbulage, Xiaodonggou, and Jiguanshan). Compared with plutons related to the Cu–(Mo) deposits, the mineralized granites of the three Mo-dominant deposits are characterized by high SiO2, low CaO, Al2O3, Fe2O3T, and Sr (Fig. 12), and pronounced negative Eu anomalies (Fig. 13) which indicate highly fractional crystallization. While plutons related with Cu (Mo) deposits are characterized by relatively low SiO 2, high Ca, Al, low Fe, low Rb/Sr value and no negative Eu anomalies. Using a Harker diagrams (Fig. 12), it is clear that comparing to plutons of Cu (Mo) deposits, those of Mo-dominant deposits have higher SiO2 concentrations, lower CaO, Al2O3, MgO and Fe2O3 contents, subequal Rb contents and much lower Sr. These differences reflect greater fractionation of the Mo-dominant deposit granites, especially the separation of feldspars. Plagioclase fractionation led to the depletion of Al2O3, CaO, and Sr, and negative Eu anomalies, while the separation of K-feldspar caused Ba depletion. Therefore, it can be concluded that advanced fractional crystallization is a key factor in favoring Mo over Cu mineralization. The geochemical behavior of Mo can be used to explain how prolonged fractional crystallization favors Mo mineralization. Molybdenum is an incompatible element with a crystal/melt partition coefficient (Dcrystal/melt) << 1 (DMo crystal/melt = 0.02), meaning that it becomes enriched in the melt due to fractional crystallization prior to the melt becoming water-saturated. Due to the high partition coefficient of Mo between fluid and melt (D 23

Mo fluid/melt

= 2.5), as the melt becomes water-saturated the Mo is preferentially taken up by the

H2O-fluid phase, resulting in a Mo-enriched ore-forming fluid (Candela and Holland, 1984, 1986). In contrast, the crystal/melt partition coefficient of Cu (DCu crystal/melt) = 2, meaning that Cu is preferentially incorporated into the fractionating minerals (e.g., sulfide or biotite), leading to Cu depletion in the residual magma. Despite the high fluid/melt partition coefficient of Cu (DCu fluid/melt = 9.1), the low abundance of Cu in the melt due to fractional crystallization would result in a barren fluid. Porphyry-style mineralization associated with such a high fractioned intrusion may give rise to Mo mineralization and hardly form an economic Cu deposit (Shu et al., 2014). The Mo-dominant deposits show pronounced negative Eu anomalies on REE diagrams (Fig. 13). As discussed above, Eu anomalies indicate that the Mo-related granites underwent extensive plagioclase fractionation. The listric REE patterns of the Cu deposit samples indicate hornblende fractionation, for that hornblende preferentially partition middle REE (Green and Pearson, 1985). Relatively low Y contents in the Cu deposit samples also indicate hornblende fractionation. Crystallization of hornblende indicates that the magma contains more water contents (≥4%; Naney, 1983), which would prohibit plagioclase fractionation (Moore and Carmichael, 1998). In addition, a notable phenomenon that the Dongbulage granite porphyry scarcely contains hornblende and biotite; while hornblende and biotite are commonly observed in the Taibudai granite, can also convinces this statement. Therefore, the magmas associated with Cu deposits are 24

likely to have been more hydrous than those related to Mo-dominant deposits. In summary, fractional crystallization and initial magma water content are key factors in determining whether Mo or Cu mineralization occurs. Prolonged crystal fractionation and lower magmatic water contents will lead to the formation of a Mo-rich, Cu-poor deposit, whereas less fractionated and more hydrous magmas will facilitate the formation of Mo-poor, Cu-rich deposits.

7. Conclusions Based on whole-rock geochemical, U–Pb zircon, and molybdenite Re–Os data, we arrived at the following conclusions. (1) U–Pb zircon dating shows that the Dongbulage ore-related granite porphyry formed at 164.5 ± 1.7 Ma, consistent with a molybdenite Re–Os weighted mean model age of 164.3 ± 1.2 Ma. The U–Pb zircon age of the Taibudai ore-related monzogranite is 137.9 ± 1.7 Ma. (2) A peak in mineralization between 180 and 160 Ma was related to westward subduction of the Paleo-Pacific during the Late Jurassic. In the Early Cretaceous, the switch from a compressional to extensional tectonic regime was responsible for the 140–130 Ma mineralization event. (3) Fractional crystallization is one of the key factors triggering the selected mineralization of Cu or Mo. Prolonged fractional crystallization leads to Mo-rich, 25

Cu-poor magmas and the formation of Mo-dominant deposits. Magmas that do not experience extensive crystal fractionation are likely to produce Cu–(Mo) deposits. Higher magma water contents promote the formation of Cu–(Mo) deposits, while lower contents favor the formation of Mo-dominant deposits.

Acknowledgements The research was funded by the National Key R&D Program of China (2017YFC0601302) and the National Nature Science Foundation of China (No. 41390445). Yitao Zhou was also funded by a China Scholarship Council award (No. 201606010085). We are grateful to two anonymous reviewers and the editors for their critical reviews and insightful comments that allowed us to significantly improve the manuscript.

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Metallogenic Belt. Journal of Jilin University (Earth of Science Edition) 41, 1705–1714 (in Chinese with English abstract). Zeng, Q.D., Liu, J.M., Chu, S.X., Wang, Y.B., Sun, Y., Duan, X.X., Zhou, L.L., 2012. Mesozoic molybdenum deposits in the East Xingmeng orogenic belt, northeast China: Characteristics and tectonic setting. International Geology Review 54, 1843–1869. Zhang, L.C., Xiao, W.J., Qin, K.Z., Zhang, Q., 2006. The adakite connection of the Tuwu-Yandong copper porphyry belt, eastern Tianshan, NW China: trace element and Sr–Nd–Pb isotope geochemistry. Mineralium Deposita 41, 188–200. Zhang, L.C., Wu, H.Y., Wan, B., Chen, Z.G., 2009. Ages and geodynamic settings of Xilamulun Mo-Cu metallogenic belt in northern part of the North China Craton. Gondwana Research 16, 243–254. Zhang, L.C., Wu, H.Y., Xiang, P., Zhang, X.J., Chen, Z.G., Wan, B., 2010. Ore-forming processes and mineralization of complex tectonic system during the Mesozoic: A case from Xilamulun Cu-Mo metallogenic belt. Acta Petrologica Sinica 26, 1351–1362 (in Chinese with English abstract). Zhou, Y.T., Lai, Y., Shu, Q.H., Sun, Y., Xu, J.J., Liang, Y.W., 2017. Geochronology and fluid inclusion study of the Shabutai porphyry Mo deposit, Inner Mongolia. Ore Geology Reviews 81, 745–759. Zhou, Z.H., Lu, L.S., Feng, J.R., Li, C., Li, T., 2010. Molybdenite Re-Os ages of 38

Huanggang skarn Sn-Fe deposit and their geological significance, Inner Mongolia. Acta Petrologica Sinica 26, 667–679 (in Chinese with English abstract). Zhou, Z.H., Mao, J.W., Wu, X.L., Ouyang, H.G., 2014. Geochronology and geochemistry constraints of the Early Cretaceous Taibudai porphyry Cu deposit, northeast China, and its tectonic significance. Journal of Asian Earth Sciences 103, 212–228. Zou, T., Wang, J.B., Wang, Y.W., Yuan, J.M., Lin, L.J., Dou, J.L., 2011. Geochemical Characteristics of the Granitic Rocks in the Aolunhua Porphyry Copper-Molybdenum Deposit, Inner Mongolia. Acta Geologica Sinica 85, 213–223.

Figure captions Fig. 1. (A) Tectonic subdivisions of northeastern China (redrawn from Wu et al., 2011a and Zeng et al., 2012); (B) Regional geological map of the central-southern Great Xing’an Range (redrawn from Inner Mongolia Bureau of Geology and Mineral Resources, 1991), showing the location of the Dongbulage Mo deposit and the Taibudai Cu deposit.

Fig. 2.

Geologic map of the Dongbulage Mo deposit and its adjacent areas (redrawn

from Inner Mongolia Zhongxing Geological Survey Corp., 2010). 39

Fig. 3. Hand specimens photographs and photomicrographs of igneous rocks and their alteration features of the Dongbulage Mo deposit: (A) Granite porphyry with quartz–molybdenite veinlets; (B) Molybdenite disseminated in the porphyry; (C) Fluorite in wall rock; (D) Phyllic alteration; (E) Chloritization in the porphyry; (F) Carbonate alteration of the porphyry; (G) Molybdenite disseminated in the porphyry; (H) Galena in wall rock; (I) Sphalerite in wall rock. Abbreviations: Fl = fluorite; Mo = molybdenite; Gn = galena; Sp = sphalerite.

Fig. 4. Geologic map of the Taibudai Cu deposit and adjacent areas (modified after Chihang Mining Corp., 2012).

Fig. 5. Hand specimens photographs and photomicrographs of igneous rocks and their alteration features of Taibudai Cu deposit: (A) Weak potassic alteration around an early veinlet; (B) Early K-feldspar veins, representing potassic alteration; (C) Quartz vein containing molybdenite and pyrite; (D) Late banded sulfide vein; (E) Late-stage barren vein cutting early mineralized veins; (F) Hornblende and biotite in the granite; (G) Molybdenite in quartz vein; (H) Galena and sphalerite in quartz vein; (I) Sphalerite associated with chalcopyrite in quartz vein. Abbreviations: Mo = molybdenite; Kfs = K-feldspar; Qz = quartz; Py = pyrite; Ccp = 40

chalcopyrite; Gn = galena; Sp = sphalerite; Hb = hornblende; Bi = biotite.

Fig. 6. Classification of the Dongbulage and Taibudai granitoid samples on K2O vs. SiO2 and A/CNK-A/NK diagrams.

Fig. 7. Chondrite-normalized REE and primitive mantle-normalized trace element spider diagrams for the Dongbulage and Taibudai granitoids. Chondrite and primitive-mantle values are from Sun and McDonough(1989).

Fig. 8. Zircon U-Pb concordia diagrams for (A) granite sample DBLG-3 and (B) granite porphyry sample DBLG-9 from the Dongbulage Mo deposit and (C) monzogranite sample TBD-64 from the Taibudai Cu deposit. Insets show cathodoluminescence images of analyzed zircons.

Fig. 9. (A) Re-Os isochron diagram and (B) weighted mean model age diagram for molybdenite samples from the Dongbulage deposit.

Fig. 10. FeO*/MgO vs. Zr+ Nb+Ce+Y and (K2O+Na2O)/CaO vs. Zr+Nb+Ce+Y diagrams (after Whalen et al., 1987) for samples analyzed during this study. FG = fractionated M-, I-, and S-type granites; OGT = unfractionated M-, I-, and S-type granites. 41

Fig. 11. Diagrams of La/Sm vs. La and Zr/Nb vs. Zr for the Dongbulage and Taibudai plutons. Also shown for comparison are the Tuwu-Yandong plagioclase porphyries that host the Tuwu-Yandong Cu deposit (data from Zhang et al., 2010)

Fig. 12. Harker diagrams showing data for granites associated with six porphyry Cu-Mo and Mo deposits in the central-southern Great Xing’an Range. Data for the Aolunhua, Jiguanshan, Xiaodonggou, Kulitu, Dongbulage and Taibudai deposits are the mean values from Zou et al. (2011), Wu et al. (2014), Nie et al. (2007), Ma et al. (2013), Wu et al. (2008), and this study, respectively.

Fig. 13. Primitive-mantle and chondrite-normalized trace element diagrams for the granitic rocks associated with six porphyry Cu–(Mo) and Mo deposits in the central–southern Great Xing’an Range. Data sources are the same as in Fig. 12.

42

43

44

45

46

47

48

49

50

51

Table 1 Chemical compositions for the Dongbulage and Taibudai plutons Samples

Granite Porphyry DBLG-8

Granite

DBLG-12

DBLG-16

DBLG-17

DBLG-18

DBLG-32

DBLG-2

DBLG-3

DBLG-1

DBLG-7

Major oxides (wt%) SiO2

76.17

74.96

76.36

75.38

77.16

77.45

76.23

75.30

73.61

72.16

TiO2

0.08

0.14

0.06

0.06

0.06

0.06

0.10

0.11

0.13

0.13

Al2O3

12.2

12.95

12.17

11.69

11.66

12.04

12.64

13.26

13.93

14.52

TFe2O3

0.95

1.64

0.91

1.43

1.01

1.08

1.17

1.35

1.13

0.95

MgO

0.11

0.20

0.15

0.17

0.14

0.09

0.11

0.13

0.17

0.17

K2O

5.67

3.82

6.3

6.48

5.86

4.45

4.65

4.68

5.00

4.96

Na2O

2.86

4.35

1.55

1.14

1.69

3.62

3.87

4.20

4.19

4.60

CaO

0.65

0.76

0.62

1.34

0.59

0.56

0.65

0.66

0.72

0.96

MnO

0.03

0.04

0.02

0.04

0.02

0.02

0.04

0.04

0.02

0.02

P2O5

0.02

0.04

0.01

0.01

0.01

0.01

0.02

0.03

0.03

0.03

LOL

0.87

0.87

1.34

1.92

1.20

0.70

0.22

0.37

0.55

1.19

Total

99.61

99.77

99.49

99.66

99.4

100.08

99.7

100.13

99.48

99.69

A/NK

1.12

1.15

1.30

1.31

1.28

1.12

1.11

1.11

1.13

1.12

A/CNK

1.01

1.02

1.16

1.03

1.14

1.02

1.00

1.01

1.02

0.99

Na2O+K2O

8.53

8.17

7.85

7.62

7.55

8.07

8.52

8.88

9.19

9.56

K2O/Na2O

1.98

0.88

4.06

5.68

3.47

1.23

1.20

1.11

1.19

1.08

Trace elements（ppm） La

11.3

31.2

14.2

15.2

19.3

10.7

21.1

31.0

33.5

29.3

Ce

29.4

64.7

33.8

35.5

45.6

31.5

31.6

56.4

67.6

59.9

Pr

3.31

7.30

4.09

4.38

5.67

3.65

4.90

7.25

7.22

6.43

Nd

13.5

26.3

15.9

17.1

22.0

14.8

17.8

25.3

25.7

22.9

Sm

3.68

5.40

4.27

4.62

5.41

4.01

3.46

5.11

4.33

4.02

52

Eu

0.10

0.35

0.23

0.33

0.26

0.06

0.29

0.29

0.43

0.33

Gd

4.35

4.70

4.11

4.60

5.28

4.34

2.99

4.54

3.38

3.27

Tb

0.79

0.74

0.69

0.84

0.90

0.79

0.51

0.70

0.51

0.48

Dy

5.25

4.08

4.45

5.17

5.55

5.23

2.97

3.97

2.78

2.55

Ho

1.10

0.75

0.90

1.09

1.09

1.09

0.56

0.74

0.53

0.50

Er

3.34

2.22

2.95

3.52

3.65

3.53

1.83

2.33

1.67

1.61

Tm

0.48

0.31

0.42

0.52

0.53

0.52

0.26

0.32

0.23

0.23

Yb

3.29

2.13

3.02

3.68

3.66

3.60

1.79

2.30

1.62

1.63

Lu

0.43

0.30

0.42

0.54

0.53

0.52

0.26

0.33

0.25

0.24

Y

32.4

22.6

27.4

32.5

32.9

33.3

17.4

22.1

15.2

14.8

Zr

128

204

114

105

101

112

121

184

195

209

Hf

6.16

6.90

4.99

4.69

4.56

5.68

4.39

6.64

6.54

6.60

V

4.63

4.88

0.73

1.12

0.69

0.32

2.79

2.85

1.78

1.61

Sc

1.52

3.11

0.87

1.23

1.12

1.35

1.52

1.80

2.51

1.82

Ti

440

835

374

355

367

302

558

623

763

742

Ga

21.3

19.5

17.4

17.0

15.9

20.2

17.5

19.3

19.4

19.4

Nb

12.8

11.2

11.8

9.57

11.2

12.6

9.84

12.7

10.2

10.5

Ta

1.33

0.86

1.25

1.05

1.13

1.21

0.85

1.13

0.86

0.86

Pb

4.85

11.1

16.1

68.2

70.9

8.78

12.2

12.4

21.1

16.7

Th

16.4

14.1

16.7

19.2

19.1

15.0

8.89

13.4

13.8

9.67

U

5.21

2.34

5.25

5.75

5.85

5.43

3.52

5.67

4.00

1.75

Rb

101

118

202

222

195

141

150

157

163

170

Sr

39.6

66.5

71.4

90.2

80.8

14.3

43.0

48.4

69.1

46.6

Ba

148

168

491

522

460

54.5

153

153

270

252

ΣREE

80.3

151

89.5

97.1

120

84.3

90.3

141

150

133

53

Table 1: Continued Sample

TBD-30

TBD-54

TBD-55

TBD-56

TBD-57

TBD-58

TBD-59

TBD-60

TBD-61

69.8 0.31 14.45 2.37 0.87 4.18 4.11 1.98 0.07 0.02 1.22 99.51 1.28 0.97 8.29 1.02

71.0 0.30 13.85 2.51 0.83 3.39 4.19 1.92 0.04 0.02 0.90 99.00 1.31 0.98 7.58 0.81

70.0 0.40 14.55 3.22 1.35 3.45 3.40 2.79 0.06 0.03 1.26 100.57 1.56 1.01 6.85 1.01

70.9 0.34 13.85 2.61 0.92 2.92 4.33 2.15 0.06 0.02 1.11 99.25 1.35 0.97 7.25 0.67

67.8 0.39 14.85 3.05 1.29 3.06 4.60 2.75 0.08 0.03 1.52 99.48 1.36 0.93 7.66 0.67

69.7 0.40 14.30 3.21 1.37 3.03 4.08 2.68 0.07 0.02 1.21 100.12 1.43 0.96 7.11 0.74

69.9 0.32 14.30 2.46 0.85 3.87 4.08 2.12 0.07 0.02 1.34 99.40 1.31 0.97 7.95 0.95

71.3 0.33 14.05 2.49 0.86 3.80 4.15 1.92 0.04 0.02 0.89 99.92 1.28 0.97 7.95 0.92

27.3 55.8 5.72 19.1 3.15

26.5 54.8 5.97 20.6 3.54

32.8 62.3 6.49 22.1 3.74

29.2 50.3 4.68 14.7 2.14

29.6 58.7 6.07 20.1 3.30

30.2 60.2 6.27 21.6 3.57

29.4 60.7 6.31 21.7 3.61

25.4 53.7 5.73 19.4 3.40

Major oxides（wt%） SiO2 TiO2 Al2O3 TFe2O3 MgO K2O Na2O CaO MnO P2O5 LOL Total A/NK A/CNK K2O+Na2O K2O/Na2O

68.0 0.40 14.50 3.18 1.34 3.41 4.03 2.61 0.10 0.02 1.83 99.48 1.40 0.96 7.44 0.85

Trace elements（ppm） La 30.0 Ce 59.6 Pr 6.11 Nd 20.9 Sm 3.46

54

Eu Gd Tb Dy Ho Er Tm Yb Lu Y Zr Hf V Sc Ti Ga Nb Ta Pb Th U Rb Sr Ba ΣREE

0.78 2.76 0.40 2.43 0.47 1.48 0.23 1.61 0.25 14.1 155 4.4 51 6 2500 18.7 8.2 0.8 9 14.0 3.84 146 480 647 131

0.75 2.38 0.35 2.13 0.41 1.42 0.20 1.53 0.24 12.9 168 4.6 32 4 1900 17.4 7.8 0.7 14 18.9 4.11 154 420 1265 121

0.72 2.68 0.40 2.41 0.50 1.58 0.24 1.79 0.29 15.0 156 4.3 34 4 1900 17.8 8.8 0.8 11 20.50 2.89 164 393 553 122

0.85 2.84 0.42 2.55 0.50 1.61 0.26 1.74 0.28 15.0 180 5.0 52 6 2300 19.2 8.4 0.8 8 13.4 4.39 142 471 655 139

0.61 1.64 0.25 1.45 0.31 1.06 0.17 1.36 0.23 10.4 162 4.6 40 4 2000 19.2 8.6 0.8 7 18.0 3.94 160 402 474 108

0.84 2.68 0.38 2.28 0.46 1.46 0.21 1.63 0.25 13.6 150 4.3 50 6 2400 19.4 8.4 0.8 8 13.7 3.40 132 512 602 128

0.80 2.74 0.39 2.39 0.47 1.51 0.22 1.63 0.25 14.4 141 4.0 51 6 2500 19.0 8.3 0.8 7 14.0 2.80 126 496 607 132

0.71 2.76 0.41 2.41 0.46 1.53 0.22 1.80 0.29 15.0 170 4.8 35 4 2000 17.9 9.5 0.8 15 22.6 4.06 157 393 759 132

0.73 2.63 0.39 2.37 0.49 1.59 0.24 1.83 0.28 14.7 173 4.9 36 4 2000 17.2 8.7 0.8 11 18.7 2.61 170 393 756 118

55

Table 2 Zircon U-Pb isotopic data for Dongbulage plutons (zircons from Sample DBLG-03 and DBLG-09) and Taibudai plutons (zircons from Sample TBD-64). Spot

Th(ppm)

U(ppm)

Th/U

207

Pb/206Pb

1σ

207

Pb/235U

1σ

206

Pb/238U

1σ

207

Pb/206Pb

1σ

207

Pb/235U

1σ

206

Pb/238U

1σ

DBLG-03 01

59.70

110.65

0.54

0.04837

0.00779

0.17070

0.02720

0.02561

0.00083

117

267

160

24

163

5

02

59.61

86.29

0.69

0.05105

0.02091

0.19222

0.07847

0.02732

0.00112

243

653

179

67

174

7

03

609.87

1411.96

0.43

0.04830

0.00362

0.17894

0.01279

0.02687

0.00060

114

168

167

11

171

4

04

358.05

283.17

1.26

0.04957

0.00606

0.18221

0.02199

0.02668

0.00080

175

215

170

19

170

5

05

303.45

317.68

0.96

0.04824

0.00313

0.17766

0.01129

0.02673

0.00067

111

96

166

10

170

4

06

76.68

91.76

0.84

0.04961

0.00647

0.18097

0.02318

0.02647

0.00090

177

224

169

20

168

6

07

201.17

748.17

0.27

0.05022

0.00207

0.18657

0.00756

0.02696

0.00061

205

53

174

6

171

4

08

91.23

202.30

0.45

0.04976

0.00394

0.18575

0.01444

0.02709

0.00073

184

126

173

12

172

5

09

310.57

390.59

0.80

0.05045

0.00276

0.19222

0.01029

0.02765

0.00067

216

79

179

9

176

4

10

51.06

91.55

0.56

0.04927

0.00638

0.18250

0.02336

0.02688

0.00080

161

229

170

20

171

5

11

548.35

550.98

1.00

0.04680

0.00220

0.17205

0.00796

0.02668

0.00061

39

59

161

7

170

4

12

102.72

123.52

0.83

0.04736

0.00586

0.15864

0.01941

0.02431

0.00071

67

215

150

17

155

4

13

180.93

395.00

0.46

0.04982

0.00267

0.18662

0.00980

0.02719

0.00065

187

78

174

8

173

4

14

37.61

84.43

0.45

0.04978

0.00687

0.18180

0.02479

0.02651

0.00081

185

246

170

21

169

5

15

140.55

360.36

0.39

0.05143

0.00296

0.21200

0.01198

0.02992

0.00073

260

85

195

10

190

5

16

613.94

1049.49

0.58

0.04960

0.00200

0.17408

0.00692

0.02548

0.00057

176

52

163

6

162

4

17

47.39

124.94

0.38

0.04729

0.00811

0.17312

0.02949

0.02657

0.00080

64

270

162

26

169

5

18

301.14

553.04

0.54

0.05038

0.00265

0.18564

0.00958

0.02674

0.00064

213

75

173

8

170

4

19

118.59

113.77

1.04

0.04965

0.00653

0.16910

0.02199

0.02472

0.00075

179

232

159

19

157

5

20

98.38

363.49

0.27

0.05085

0.00510

0.18690

0.01863

0.02668

0.00065

234

180

174

16

170

4

56

21

101.82

132.36

0.77

0.05015

0.00632

0.18608

0.02315

0.02694

0.00082

202

223

173

20

171

5

22

229.65

208.75

1.10

0.04921

0.00372

0.18039

0.01337

0.02661

0.00072

158

117

168

12

169

5

23

53.29

71.77

0.74

0.04605

0.02840

0.15618

0.09603

0.02460

0.00116

147

84

157

7

207

206

Pb/ Pb

1σ

207

235

238

206

235

246

170

220

335

0.00062

212

0.02671

0.00077

0.02583

0.02693

0.19094

0.01416

0.00436

0.18359

206

238

Pb/ U

1σ

21

170

5

187

35

185

6

83

169

9

166

4

143

143

168

14

170

5

0.00087

209

248

174

22

171

5

0.02562

0.00062

375

124

177

12

163

4

0.01601

0.02718

0.00077

149

143

171

14

173

5

spot

Th(ppm)

U(ppm)

Th/U

Pb/ Pb

24

343.71

304.67

1.13

0.04948

0.00674

0.18263

0.02465

0.02679

0.00078

171

25

34.37

71.39

0.48

0.05054

0.01029

0.20277

0.04095

0.02912

0.00100

26

384.78

626.32

0.61

0.05036

0.00280

0.18069

0.00992

0.02604

27

154.37

171.58

0.90

0.04889

0.00436

0.17987

0.01574

28

115.02

150.94

0.76

0.05030

0.00705

0.18659

29

214.61

615.98

0.35

0.05410

0.00405

30

209.21

204.33

1.02

0.04903

1σ

207

1σ

Pb/ U

1σ

976 207

Pb/ U

Pb/ U

1σ

206

DBLG-09 01

934.54

1347.61

0.69

0.05104

0.00176

0.18440

0.00638

0.02622

0.00058

243

41

172

5

167

4

02

415.19

819.03

0.51

0.04971

0.00170

0.17996

0.00615

0.02627

0.00059

181

41

168

5

167

4

03

469.65

854.50

0.55

0.05048

0.00217

0.18248

0.00782

0.02623

0.00059

217

58

170

7

167

4

04

184.04

282.10

0.65

0.04898

0.00236

0.16627

0.00788

0.02463

0.00060

147

66

156

7

157

4

05

156.39

210.59

0.74

0.05042

0.00485

0.17915

0.01701

0.02578

0.00071

214

163

167

15

164

4

06

113.94

268.71

0.42

0.05343

0.00271

0.20515

0.01022

0.02786

0.00069

347

68

189

9

177

4

07

141.53

402.93

0.35

0.05060

0.00564

0.18666

0.02077

0.02677

0.00064

223

206

174

18

170

4

08

180.03

335.23

0.54

0.05019

0.00418

0.17946

0.01489

0.02594

0.00062

204

143

168

13

165

4

09

52.95

147.78

0.36

0.04881

0.00343

0.17851

0.01232

0.02653

0.00071

139

106

167

11

169

4

10

342.28

495.41

0.69

0.04933

0.00211

0.17337

0.00734

0.02550

0.00060

164

56

162

6

162

4

11

415.55

548.33

0.76

0.05239

0.00221

0.18099

0.00752

0.02507

0.00060

302

53

169

6

160

4

12

725.63

1105.51

0.66

0.05072

0.00186

0.17529

0.00639

0.02507

0.00058

228

44

164

6

160

4

13

348.69

685.53

0.51

0.05069

0.00213

0.17641

0.00732

0.02525

0.00060

227

53

165

6

161

4

14

191.43

318.40

0.60

0.04931

0.00252

0.18146

0.00913

0.02670

0.00066

163

72

169

8

170

4

57

15

402.41

516.81

0.78

0.04921

0.00331

0.17184

0.01153

0.02534

0.00060

158

109

161

10

161

4

16

391.03

1018.03

0.38

0.05049

0.00184

0.17095

0.00621

0.02456

0.00057

218

44

160

5

156

4

17

317.68

833.55

0.38

0.05106

0.00196

0.20110

0.00769

0.02857

0.00067

244

47

186

7

182

4

207

206

235

238

206

235

65

286

132

49

0.00059

193

0.02583

0.00063

0.00779

0.02489

0.18131

0.00917

0.00224

0.18245

0.04850

0.00229

0.72

0.04963

159.20

0.41

52.28

82.40

29

70.81

30

272.11

206

238

1σ

12

285

7

186

7

190

4

55

161

6

158

4

254

62

170

7

164

4

0.00061

66

63

153

7

158

4

0.02663

0.00067

166

72

169

8

169

4

0.00839

0.02748

0.00067

108

63

170

7

175

4

0.17498

0.00816

0.02618

0.00064

124

64

164

7

167

4

0.00275

0.17159

0.00937

0.02508

0.00064

178

80

161

8

160

4

0.05112

0.00349

0.18954

0.01270

0.02690

0.00074

246

103

176

11

171

5

0.63

0.05268

0.00519

0.18827

0.01815

0.02593

0.00084

315

159

175

16

165

5

84.36

0.84

0.05424

0.00375

0.33341

0.02259

0.04459

0.00126

381

102

292

17

281

8

298.99

0.91

0.05312

0.00275

0.19412

0.00989

0.02651

0.00068

334

70

180

8

169

4

spot

Th(ppm)

U(ppm)

Th/U

Pb/ Pb

18

77.56

170.51

0.45

0.05218

0.00255

0.32535

0.01568

0.04523

0.00113

293

19

462.38

655.47

0.71

0.04867

0.00190

0.20082

0.00779

0.02993

0.00070

20

380.05

615.42

0.62

0.04995

0.00212

0.17136

0.00720

0.02489

21

319.83

478.37

0.67

0.05130

0.00240

0.18262

0.00844

22

180.39

404.32

0.45

0.04734

0.00230

0.16240

23

160.16

312.30

0.51

0.04939

0.00254

24

290.69

393.12

0.74

0.04817

25

146.11

368.10

0.40

26

198.78

274.20

27

65.99

28

1σ

207

Pb/ U

Pb/ U

1σ

207

1σ

Pb/ U

1σ

206

Pb/ U

Pb/ Pb

1σ

207

TBD-64 01

497.06

607.02

0.82

0.04785

0.00117

0.14804

0.00340

0.02246

0.00020

92

37

140

3

143

2

02

243.87

389.20

0.63

0.04836

0.00154

0.14517

0.00442

0.02179

0.00021

117

53

138

4

139

2

03

273.21

445.05

0.61

0.04694

0.00140

0.13923

0.00398

0.02153

0.00020

46

46

132

4

137

2

04

209.75

344.74

0.61

0.04943

0.00176

0.14783

0.00506

0.02171

0.00023

168

60

140

4

138

2

05

313.73

474.84

0.66

0.04946

0.00125

0.14799

0.00353

0.02172

0.00019

170

39

140

3

139

2

06

101.17

1071.60

0.09

0.05069

0.00093

0.14243

0.00237

0.02039

0.00017

227

23

135

2

130

2

07

230.53

368.77

0.63

0.04889

0.00169

0.14618

0.00488

0.02170

0.00021

143

60

139

4

138

2

08

246.47

361.73

0.68

0.04759

0.00195

0.14089

0.00560

0.02149

0.00024

79

68

134

5

137

4

58

09

271.51

512.57

0.53

0.04980

0.00138

0.14584

0.00383

0.02126

0.00021

186

43

138

3

136

2

10

216.87

361.69

0.60

0.04839

0.00205

0.14927

0.00615

0.02239

0.00024

118

75

141

5

143

4

11

373.60

542.24

0.69

0.04862

0.00131

0.14122

0.00361

0.02108

0.00020

130

42

134

3

134

2

207

206

235

238

206

235

40

137

65

57

0.00022

206

0.02181

0.00020

0.00310

0.02189

0.13057

0.00376

0.00156

0.14171

0.04920

0.00132

0.69

0.04898

381.60

0.84

257.48

403.68

23

327.46

24 25

206

238

1σ

3

133

2

134

4

138

2

47

140

4

137

2

164

40

140

3

139

2

0.00019

159

33

141

3

140

2

0.02038

0.00019

24

44

125

3

130

2

0.00433

0.02098

0.00021

148

53

135

4

134

2

0.14206

0.00359

0.02095

0.00020

157

41

135

3

134

2

0.00139

0.14893

0.00402

0.02207

0.00021

147

45

141

4

141

2

0.04932

0.00145

0.14854

0.00417

0.02186

0.00021

163

48

141

4

139

2

0.64

0.04878

0.00148

0.14323

0.00414

0.02131

0.00021

137

49

136

4

136

2

492.33

0.67

0.04979

0.00148

0.14764

0.00418

0.02152

0.00022

185

47

140

4

137

2

265.94

358.99

0.74

0.04974

0.00182

0.14548

0.00512

0.02123

0.00024

183

61

138

5

135

4

380.76

539.86

0.71

0.04860

0.00122

0.15011

0.00355

0.02241

0.00020

129

39

142

3

143

2

spot

Th(ppm)

U(ppm)

Th/U

Pb/ Pb

12

402.58

567.16

0.71

0.05057

0.00132

0.14495

0.00359

0.02080

0.00019

221

13

281.38

422.90

0.67

0.04732

0.00168

0.14126

0.00484

0.02167

0.00023

14

207.31

401.14

0.52

0.05023

0.00151

0.14816

0.00425

0.02141

15

286.33

445.85

0.64

0.04934

0.00127

0.14829

0.00361

16

443.30

551.66

0.80

0.04923

0.00110

0.14849

17

333.69

504.94

0.66

0.04650

0.00139

18

215.28

423.66

0.51

0.04901

19

487.21

679.44

0.72

20

316.46

458.00

21

320.44

22

1σ

207

Pb/ U

Pb/ U

1σ

207

1σ

Pb/ U

1σ

206

Pb/ U

Pb/ Pb

1σ

207

59

Table 3 Re-Os data for molybdenite from the Dongbulage porphyry Mo deposit Sample Info.

w(Re)/μg.g-1

w(普 Os)/ng.g-1

w(187Re) /μg.g-1

w(187Os ) /ng.g-1

Model age(Ma)

Sample.No

weight（g)

Measured

Uncertainties

Measured

Uncertainties

Measured

Uncertainties

Measured

Uncertainties

Measured

Uncertainties

DB-T1

0.04975

26.01

0.22

0.013

0.014

16.35

0.14

44.64

0.39

163.66

2.38

DB-T2

0.04001

25.98

0.25

0.008

0.055

16.33

0.16

44.61

0.41

163.78

2.57

DB-T4

0.04009

2.520

0.026

0.019

0.020

1.584

0.016

4.373

0.040

165.51

2.63

DB-T3

0.03000

38.22

0.46

0.009

0.014

24.02

0.29

66.08

0.54

164.89

2.75

DB-T5

0.03009

2.818

0.033

0.014

0.028

1.771

0.021

4.833

0.052

163.55

2.93

Note：Model age is calculated as the follow formula:

t

1



187

ln( 187

Os  1) Re

Decay consistant (187Re)=1.66610-11 a-1（1.02%）（Smolar et al., 1996）.

60

Table 4 Geochemical characters of several deposits in Central-South Great Xing’an Range Trace elements Depostis Mineral assemblage Ore-containing rock Major oxides characters characters Rb = 125.5-169.5 ppm; Chalcopyrite, Taibudai Cu SiO2 = 68.00%-71.30%; Sr = 393-512 ppm; molybdenite, accessory Monzonitic granite (Mo) deposit CaO = 1.92%-2.79% Rb/Sr = 0.25-0.43; No galena, sphalerite negative Eu anomalies Rb = 194-218 ppm; Sr = Kulitu Cu (Mo) Molybdenite, Porphyritic monzonitic SiO2 = 70.60%-72.95%; 227-1205 ppm; Rb/Sr = deposit chalcopyrite, pyrite granite CaO = 0.95%-1.34% 0.17-1.10; weak negative Eu anomalies Rb = 80-121 ppm; Sr = Aolunhua Mo Molybdenite, SiO2 = 67.10%-70.36%; 535-794 ppm; Rb/Sr = Monzogranic porphyry (Cu) Deposit chalcopyrite, pyrite CaO = 1.81%-3.49% 0.10-0.23; No negative Eu anomalies Rb = 101-222 ppm; Sr = Dongbulage Mo Molybdenite, accessory SiO2 = 74.96%-77.45%; 14.3-90.2 ppm; Rb/Sr = porphyry deposit galena, sphalerite CaO = 0.56%-1.34% 1.77-9.86; remarkable negative Eu anomalies Rb = 174-245 ppm; Sr = Molybdenite, pyrite, Xiaodonggou SiO2 = 74.73%-75.77%; 66.9-114.4 ppm; Rb/Sr chalcopyrite, sphalerite, Porphyritic granite Mo deposit CaO = 0.45%-0.75% = 2.35-3.24; no negative pyrrhotite, magnitite Eu anomalies Rb = 178-190 ppm; Sr = Jiguanshna Mo Molybdenite, pyrite, SiO2 =77.16%-77.51%; K-feldspar granite 12.0-14.0 ppm; Rb/Sr = deposit magnetite, fluorite CaO = 0.11% 13.57-14.83; remarkable

Reference

This paper

Wu et al., 2008

Zou et al., 2011

This paper

Qin et al., 2008; Nie et al., 2007 Wu et al., 2014

61

negative Eu anomalies

62

63

Highlights The Dongbulage and the Taibudai deposits in the Great Xing’an Range, China formed at 164 Ma and 138, respectively. 

Fractional crystallization triggered mineralization of Cu or Mo. 

Water content has taken another vital role in Cu and Mo precipitation.

64