The Mesozoic Caosiyao Giant Porphyry Mo Deposit in Inner

Journal of Asian Earth Sciences 127 (2016) 281–299

Contents lists available at ScienceDirect

Journal of Asian Earth Sciences

journal homepage: www.elsevier.com/locate/jseaes

The Mesozoic Caosiyao giant porphyry Mo deposit in Inner Mongolia, North China and Paleo-Paciﬁc subduction-related magmatism in the northern North China Craton ⇑ Huaying Wu a,b,c, , Lianchang Zhang c, Franco Pirajno d, Qihai Shu a, Min Zhang b, Mingtian Zhu c, Peng Xiang a a State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, People’s Republic of China b Institute of Mineral Resources Research, China Metallurgical Geology Bureau, Beijing 100025, People’s Republic of China c Key Laboratory of Mineral Resources, Institute of Geology and Geophysics, Chinese Academy of Sciences, P.O. Box 9825, Beijing 100029, People’s Republic of China d Centre for Exploration Targeting, University of Western Australia, 35 Stirling Highway, Crawley 6005, Australia article info abstract

Article history: The Caosiyao giant porphyry Mo deposit is located in the Wulanchabu area of Inner Mongolia, within the Received 7 November 2015 northern North China Craton (NCC). It contains more than 2385 Mt of ore with an average grade of 0.075% Received in revised form 13 June 2016 Mo. In the Caosiyao mining district, Mo mineralization occurs mainly in a Mesozoic granite porphyry as Accepted 14 June 2016 disseminations and stockworks, with some Mo distributed in Archean metamorphic rocks and diabase as Available online 27 June 2016 stockworks and veins. The host granite porphyry is composed of two different phases that can be distinguished based on mineral assemblages and textures: one phase contains large and abundant phenocrysts Keywords: (coarse-grained), while the other phase is characterized by fewer and smaller phenocrysts (medium- Zircon U–Pb dating grained). Zircon U–Pb–Hf analyses of the former phase yielded a concordant 206Pb/238U age of Molybdenite Re–Os dating 206 238 e Giant porphyry Mo deposit 149.8 ± 2.4 Ma with a Pb/ U weighted mean age of 149.9 ± 2.4 Ma and Hf(t) values ranging from 206 238 Caosiyao À12.2 to 18.3, while the latter phase gave a concordant Pb/ U age of 149.0 ± 2.2 Ma with a 206 238 Northern North China Craton Pb/ U weighted mean age of 149.0 ± 2.1 Ma and eHf(t) values ranging from À13.1 to 17.7. Five sam- Paleo-Paciﬁc subduction ples of disseminated molybdenite have a 187Re–187Os isochron age of 149.5 ± 5.3 Ma with a weighted average age of 149.0 ± 1.8 Ma, whereas six veinlet-type molybdenite samples have a well-constrained 187Re–187Os isochron age of 146.9 ± 3.1 Ma and a weighted average age of 146.5 ± 0.8 Ma. Thus, it is suggested that the Mo mineralization of the Caosiyao deposit occurred during the Late Jurassic (ca. 147–149 Ma), almost coeval with the emplacement of the host granite porphyry (ca. 149–150 Ma).

The host granite porphyry is characterized by high silica (SiO2 = 71.52–74.10 wt%), relatively high levels

of oxidation (Fe2O3/FeO = 0.32–0.94 wt%) and high alkali element concentrations (Na2O+K2O = 8.21– 8.76 wt%). The host granite porphyry also shows enrichments in U and K, and depletion in Ba, Sr, P, Eu, and Ti, suggesting strong fractional crystallization of plagioclase, biotite, and accessory minerals. These

observations, together with high SiO2 contents and a high differentiation index (DI = 89.04–92.44), indicate a strong differentiation of the granite magma. Based on geological, geochronological, isotope systematics, and geochemical studies, we propose, for the first time, a genetic model for the Caosiyao porphyry Mo deposit. Under a regional extensional setting caused by far-field tectonics related to the Paleo-Pacific subduction during the Late Jurassic, a series of geodynamic, magmatic, and ore-forming processes took place, including formation of multi-directional and multi-phase faults, emplacement of the granitic host rocks, and Mo mineralization. Highly silicic, highly oxidized, and alkali-rich granitic magma, derived from partial melting of old lower crust, intruded into the country rocks. This highly differentiated granitic magma and the exsolved ore-forming fluids, enriched in Mo, migrated upward and interacted with the wall rocks. Eventually, ore minerals precipitated in fractures, resulting in the extensive deposition of molybdenite. Ó 2016 Elsevier Ltd. All rights reserved.

1. Introduction ⇑ Corresponding author at: State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, People’s Northern China and its adjacent areas have experienced a long Republic of China. and complex tectono-magmatic evolution responsible for the E-mail address: [email protected] (H. Wu). http://dx.doi.org/10.1016/j.jseaes.2016.06.014 1367-9120/Ó 2016 Elsevier Ltd. All rights reserved. 282 H. Wu et al. / Journal of Asian Earth Sciences 127 (2016) 281–299 region’s abundant mineral resources (Deng et al., 2006, 2014, tectono-magmatic evolution, including the formation of Archean– 2015; Luo et al., 1991; Mao et al., 2003, 2005; Pei et al., 1998; Paleoproterozoic lithotectonic units, Middle–Late Proterozoic rift- Pirajno and Zhou, 2015; Wu et al., 2011, 2014; Zhai et al., 2001, ing, subduction–collision associated with the closure of the 2004; Zeng et al., 2011, 2012; L.C. Zhang et al., 2009). Recently, a Paleo-Asian Ocean, and Mesozoic intracontinental tectono- large number of porphyry deposits with Mo as the major metal thermal events that are commonly referred to as the Yanshanian resource have been reported along the southern and northern mar- movement (Coleman, 1994; Meng, 2003; Pirajno et al., 2009; gins of the North China Craton (NCC) as well as its adjacent areas Pirajno, 2013; Santosh, 2010; Santosh et al., 2010; Sengör and (Fig. 1a). The Qinling orogenic belt, containing 8.5 Mt Mo, is situ- Natal’in, 1996; Xiao et al., 2003). During the Paleozoic, the geody- ated along the southern part of the NCC, and is known as the namic evolution of the Paleo-Asian Ocean influenced the northern largest Mo district worldwide (Mao et al., 2011; Li et al., 2005, NCC and its adjacent areas, and is largely responsible for the tec- 2007). Representative porphyry deposits in the Qinling Mo metal- tonic framework of these areas, especially northeast China, which logenic belt include the Shijiawan, Jinduicheng, Leimengou, Yuchil- is characterized by several convergent orogenic boundaries ing, Donggou, Nannihu, and Shangfanggou deposits (Cao et al., (Windley et al., 2002; Xiao et al., 2003; Y. Zhao et al., 2010). During 2015; Li et al., 2006; Yang, 2013; Ye et al., 2006; H.J. Zhao et al., the Mesozoic, the region entered into an intracontinental orogenic 2010; Zhu et al., 2008). Moreover, recent discoveries of several stage, which was later overprinted by the Paleo-Pacific subduction giant porphyry Mo deposits in the northern NCC and its adjacent in the east (Pei et al., 1998; Pirajno et al., 2009). This tectonic tran- areas (e.g., the Chalukou, Luming, Daheishan, Diyanqinamu, and sition from Indosinian to Yanshanian tectono-thermal events to Caosiyao deposits) have led to the recognition of this region as far-field tectonics related to the Paleo-Pacific subduction was another important Mo province, both for China and globally responsible for intense mantle–crust interaction and melting of (Leng et al., 2015; Li et al., 2014; Nie et al., 2012; Zhou et al., the lower crust, resulting in a large–scale metal mineralization in 2014). Several metallogenic belts with Mo–Cu as the principal the northern NCC and its adjacent areas (Mao et al., 1999; Zhai metals in the northern NCC and other places in the Central Asian et al., 2003). The Wulanchabu district in Inner Mongolia, where Orogenic Belt (CAOB) have been reported, including the Yanshan– several polymetallic deposits have been discovered, is a represen- Liaoning (Yanliao) Mo metallogenic belt, and the Xilamulun, Jilin- tative product of the above-mentioned tectonic and thermal Heilongjiang (Jihei), and Da-Hinggan Mo–Cu metallogenic belts events. (Chen et al., 2009, 2012; Li et al., 2014; Mao et al., 2005; Shu The Wulanchabu district is located in the northern NCC et al., 2015; L.C. Zhang et al., 2009; L.C. Zhao et al., 2010). (Fig. 1a), within the eastern Yinshan orogen. It consists of a wide Additional details of representative porphyry Mo–Cu deposits in range of lithotectonic units, including ancient continental blocks, these Mo (Cu) metallogenic belts are listed in Table 1. Mesozoic–Paleozoic continental volcano-sedimentary successions, The newly discovered Caosiyao giant porphyry Mo deposit, and a range of Precambrian and Paleozoic–Mesozoic granitoids located east of the Liangcheng fault uplift in the Wulanchabu area (Fig. 1b) (BGMRIM, 1991; Nie et al., 2012, 2013; Shen et al., within the northern NCC, is the largest porphyry Mo deposit in this 2010). The principal regional structures are represented by sets area. Mo mineralization in the mining district is developed in a of nearly E–W-, NE- and NW- striking faults. The E–W- striking Mesozoic granite porphyry and Archean metamorphic rocks, as faults include the Daqingshan and Hohhot-Wulanchabu faults, well as in a diabase. Geological characteristics, geochronology, the NE-trending faults occur in the southeast and are represented and fluid inclusion studies of the Caosiyao Mo deposit have been by the Daihai-Huangqihai and Datong-Shangyi faults, and the NW- reported in the Chinese literature (Li et al., 2012; Nie et al., 2012, trending fault is represented by the Xinghe-Shangdu fault (Fig. 1b). 2013; Wang et al., 2014; Xue et al., 2015), with only few publica- Magmatism occurred frequently from the Precambrian to the Pale- tions in the international literature. Detailed studies of hydrother- ozoic and Mesozoic in this region, and was commonly accompa- mal alteration and fluid inclusions were reported by Wang et al. nied by mineralization (Li et al., 2012; Nie et al., 2012; Pirajno (2014) and Xue et al. (2015). Nie et al. (2013) published four and Zhou, 2015). molybdenite model Re–Os ages ranging from 128.6 ± 2.4 Ma to In recent years, several polymetallic deposits and some mineral 131.9 ± 2.3 Ma, and zircon ages of 131–134 Ma for one granite por- occurrences have been discovered in the Wulanchabu district, phyry were mentioned in Li et al. (2012). However, the authors did including Pb–Zn, Au, and Mo mineral systems (Fig. 1b). The Pb– not clearly distinguish ore–related intrusions nor published iso- Zn mineralization is represented by the Liqingdi, Yangchanggou, topic age data for such intrusions. As the largest Mo deposit discov- Luweigou, and Manzhouyao Pb–Zn deposits; Au mineral systems ered in the northern NCC, the Caosiyao giant Mo deposit deserves are represented by the Bagou, Jinpensha, Dashizi, Tuopan, and Day- further studies. It is of great importance to study the petrogenesis angpo Au deposits; and the large-size Mo deposits include the of the causative granite, which cannot only provide constrains on Dasuji, Sandaogou, and Caosiyao deposits (Nie et al., 2012). the evolution of the northern NNC, but will also aid in the discovery of similar mineral systems. In this contribution, we describe the geology of the Caosiyao Mo deposit, with particular focus on 3. Ore geology petrology and systematic geochronology (molybdenite Re–Os and zircon U–Pb dating), to better constrain the magmatic–thermal The Caosiyao porphyry Mo deposit is located in Xinghe County, event that led to the Mo mineralization. Major and trace elements 75 km SE of Wulanchabu City (Inner Mongolia). It is the largest Mo as well as zircon Hf isotopic compositions were also determined for deposit in the northern NCC, with a total estimated resource of the first time to investigate the magma sources. In doing so, we aim more than 2385 Mt ore averaging 0.075 wt% Mo (NGIHBGMD, to better understand the mineralization age and tectonic back- 2013). In the Caosiyao mining area, the stratigraphic sequence con- ground of the Caosiyao Mo deposit. sists of Archean metamorphic rocks of the Jining group, which include gneiss, leptynite, migmatite, and plagioclase-amphibolite, as well as minor marble, unconformably overlain by Jurassic con- 2. Regional geology glomerate, siltstone, and marlstone (visible in drill cores), as well as Cenozoic sediments (Fig. 2). The Caosiyao deposit, located to The northern NCC and its adjacent areas are located between the southwest of the junction of the Datong–Shangyi and the Paleo-Asian Ocean and the western Circum-Pacific tectonic Xinghe–Shangdu faults (Fig. 1b), is characterized by multi- regime. The entire area has experienced a long and complex directional fault structures striking predominantly NW, NNE, NE, H. Wu et al. / Journal of Asian Earth Sciences 127 (2016) 281–299 283

Fig. 1. Tectonic subdivisions of the North China Craton and its adjacent areas (a) (modified from Zhao et al., 2001) and simplified geological map of the Wulanchabu area showing major lithological units and faults (b). The localities of Mo (Pb–Zn–Au) deposits, including the Caosiyao Mine, are also shown (modified from Bureau of Geology and Mineral Resources of Inner Mongolia (BGMRIM), 1991 and Nie et al., 2012). Table 1 284 Description of representative porphyry Mo-Cu deposits in the northern North China Craton and its adjacent areas.

Deposit Metallogenic belt Metals Host rocks Alteration/mineralization Age (Ma) Reference Chalukou Da-Hinggan Mo-Cu metallogenic belt Mo Granite porphyry K: K-feldspar, biotite, fluorite/molybdenite Zircon U-Pb age of host granite porphyry: Li et al. (2014) Quartz porphyry S: sericite, quartz, illite, hydromuscovite, 147 ± 2 fluorite/molybdenite, pyrite Pr: chlorite, fluorite, calcite/molybdenite, pyrite Diyanqinamu Mo Granite porphyry K: K-feldspar, sericite, kaolinite, smectite, Molybdenite re-Os isochron: 156 ± 2 Leng et al. illite/molybdenite, pyrite (2015) S: sericite, quartz, illite, molybdenite, pyrite Pr: chlorite, epidote, calcite, magnetite/molybdenite, pyrite Daheishan Jilin-Heilongjiang (Jihei) Mo Mo Granodioritic porphyry K: K-feldspar, quartz, molybdenite, pyrite Molybdenite re-Os isochron: 171 ± 8 Zhou et al. metallogenic belt S: sericite, quartz/molybdenite, pyrite (2014) Pr: chlorite, epidote, calcite/molybdenite, pyrite Luming Mo Monzogranite porphyry K: K-feldspar, quartz, molybdenite, pyrite Molybdenite re-Os isochron: 177 ± 4 Cheng et al. S: sericite, quartz/molybdenite, pyrite (2015) .W ta./Junlo sa at cecs17(06 281–299 (2016) 127 Sciences Earth Asian of Journal / al. et Wu H. Pr: chlorite, epidote, calcite, molybdenite, pyrite Chehugou Xilamulun Mo-Cu metallogenic belt Mo-Cu Syenogranite K: K-feldspar, biotite, quartz/molybdenite, pyrite, Chalcopyrite Rb-Sr isochron: 256 ± 7 Wan et al. Monzogranite chalcopyrite (2009) S: sericite, quartz/chalcopyrite, pyrite Gangzi Mo–Cu Granite porphyry K: K-feldspar, biotite/molybdenite, pyrite SHRIMP zircon U-Pb age of host granite Zeng et al. S: sericite, quartz/pyrite, molybdenite, chalcopyrite porphyry: 139 ± 2 (2011) Xiaodonggou Mo Porphyritic granite K: K-feldspar, biotite, quartz/magnetite, molybdenite Molybdenite re-Os isochron: 138 ± 3 Qin et al. (2008) S: sericite, quartz/molybdenite, pyrite Pr: chlorite, calcite, epidote/pyrite Jiguanshan Mo Granite porphyry, lithic tuff and K: K-feldspar, biotite, quartz/magnetite, molybdenite, Molybdenite re-Os ages: 153 ± 1; 155 ± 1 Wu et al. rhyolite pyrite (2014) S: sericite, quartz/molybdenite, pyrite Pr: chlorite, calcite, fluorite/molybdenite, pyrite, sphalerite Aolunhua Mo–Cu Monzogranitic porphyry K: K-feldspar, biotite, quartz/molybdenite, chalcopyrite, Zircon U-Pb age of host monzogranitic Wu et al. pyrite porphyry: 139 ± 1 (2011) S: sericite, quartz/chalcopyrite, pyrite, molybdenite Pr: chlorite, epidote/pyrite Banlashan Mo Granite porphyry, Rhyolite K: K-feldspar, biotite, quartz/magnetite, molybdenite, Zircon U-Pb age of host granite porphyry: X.J. Zhao et al. porphyry pyrite 134 ± 2 (2010) S: sericite, quartz/molybdenite, pyrite Pr: chlorite, calcite/molybdenite, pyrite Dazhuangke Yanshan-Liaoning (Yanliao) Mo Mo Quartz Monzonite K: K-feldspar, quartz, molybdenite, pyrite Molybdenite re-Os age: 147 ± 7 Huang et al. metallogenic belt S: sericite, quartz, molybdenite, pyrite (1996) Pr: chlorite, molybdenite, pyrite Dacaoping Mo Granodiorite, Monzogranite K: K-feldspar, quartz, molybdenite, pyrite Molybdenite re-Os isochron: 140 ± 3 Duan et al. S: sericite, quartz/molybdenite, pyrite (2007) Sadaigoumen Mo Monzonitic granite porphyry K: K-feldspar, quartz, molybdenite, pyrite Zircon U-Pb age of host granite porphyry: Wei et al. S: sericite, quartz, molybdenite, pyrite 248 ± 2 (2013) Pr: chlorite, epidote, molybdenite, pyrite Lanjiagou Mo Granite porphyry K: K-feldspar, quartz, molybdenite, pyrite Molybdenite re-Os isochron: 182 ± 7 Han et al. S: muscovite, quartz, molybdenite, pyrite (2009) Pr: chlorite, calcite/molybdenite, pyrite Jinduicheng Qinling Mo metallogenic belt Mo Granite porphyry K: K-feldspar, quartz, molybdenite, pyrite Molybdenite re-Os age: 141 ± 4 Zhu et al. S: sericite, quartz, molybdenite, pyrite (2008) Pr: chlorite, epidote /molybdenite, pyrite Shijiawan Mo Granite porphyry K: K-feldspar, quartz, molybdenite, pyrite Molybdenite re-Os age: 144 ± 2 H.J. Zhao et al. S: sericite, quartz, molybdenite, pyrite (2010) Molybdenite re-Os age: 132 ± 2 Li et al. (2006) Pr: chlorite, epidote /molybdenite, pyrite Leimengou Mo Granite porphyry K: K-feldspar, quartz, molybdenite, pyrite S: sericite, quartz, molybdenite, pyrite H. Wu et al. / Journal of Asian Earth Sciences 127 (2016) 281–299 285

and nearly E–W, which provided the channels for hydrothermal fluids (Fig. 2). The Mo orebody in the Caosiyao deposit has roughly the shape of an asymmetrical dumbbell and is E–W striking, with a length of 1900 m. In the N–S direction, its width ranges from 700 to Yang (2013) Ye et al. (2006) Yang (2013) T. Zhang et al. (2009) This study 1400 m (Fig. 2). The Mo mineralization is closely related to and distributed in the Mesozoic granite porphyry as disseminations (Fig. 3a) and stockworks (Fig. 3b). The Archean metamorphic rocks and diabase also contain some of the Mo mineralization as stockworks (Fig. 3c) and veins (Fig. 3d, e, f). Ore minerals are dominantly molybdenite and pyrite, with lesser amounts of magnetite and chalcopyrite. The gangue minerals are composed mainly of quartz, feldspar, and sericite, with minor amounts of fluorite, muscovite, biotite, and calcite. Reflected light microscopic observation shows that the molybdenite grains typically form scaly or flaky crystals and aggregates (Fig. 3g, h), whereas pyrite occurs as fractured grains and is filled by granular magnetite (Fig. 3h). In the mining district, hydrothermal alteration is pervasive, Molybdenite re-Os isochron: 145 ± 2 Molybdenite re-Os age: 116 ± 2 Molybdenite Re-Os age: 144 ± 2 Molybdenite re-Os isochron: 223 ± 3 Molybdenite re-Os isochrons: 149.5 ±146.5 5.3; ± 0.8 with alteration minerals including K-feldspar, quartz, fluorite, sericite, muscovite, biotite, pyrite, chlorite, epidote, and carbonate. Based on drill core samples, four alteration zones have been recog- nized (NGIHBGMD, 2013; Wang et al., 2014; Xue et al., 2015). From the mineralization core to the margin, these include: (1) minor silicification–potassic alteration is present in the host granite porphyry and in its adjacent filled fractures, with alteration minerals mainly consisting of quartz and K-feldspar with minor secondary biotite and sericite; (2) muscovite–quartz–sericite–fluorite alteration is distributed outside the silicification–potassic alteration zone, within the host granite porphyry, Archean metamorphic rocks, and diabase; (3) biotite–quartz–sericite–fluorite alteration is common in the mining district outside the muscovite–quartz–s ericite–fluorite alteration zone, mainly occurring in the Archean metamorphic rocks and in the host granite porphyry; finally (4) propylitic alteration forms the outermost hydrothermal alteration halo, occurring mostly in the Archean metamorphic rocks, the host granite porphyry, and the diabase. S: sericite, quartz, molybdenite, pyrite Sk/Pr: garnet, diopside, actinolite, chlorite, epidote,fluorite, calcite, pyrite Pr: chlorite, calcite/molybdenite, pyrite S: sericite, quartz, molybdenite/chalcopyrite,Pr: pyrite chlorite, calcite/molybdenite/sphalerite/Galena, pyrite K: K-feldspar, quartz, biotite, molybdenite,S: pyrite sericite, muscovite, quartz, molybdenite,Sk/Pr: hedenbergite, pyrite andradite, grammite, chlorite,fluorite, calcite, pyrite S: sericite, muscovite, quartz, fluorite,molybdenite, biotite, pyrite Pr: chlorite, epidote, molybdenite, pyrite K: K-feldspar, quartz, molybdenite, pyrite S: sericite, quartz, molybdenite, chalcopyrite,Pr: pyrite chlorite, molybdenite/sphalerite/Galena, pyrite

4. Materials and methods

4.1. Sample descriptions

Two groups of molybdenite samples were collected from drill cores of the main orebody, and systematically separated to ensure a homogeneous mineral separate (Stein et al., 2001; Selby and Monzogranite Granite porphyry Creaser, 2004). Group (1) includes ﬁve molybdenite samples from disseminated ores in the host granite porphyry. Group (2) includes six molybdenite samples, collected from veinlet-type ores in the Archean metamorphic rocks. The molybdenite samples are well- formed, euhedral molybdenite crystals without clay intergrowths. The two groups of molybdenite were magnetically separated and then handpicked under a binocular microscope. Based on mineral assemblages and textures, two different phases can be distinguished within the host granite porphyry: one phase with large and abundant phenocrysts resulting in a coarse-grained granite porphyry (Fig. 4a, c), which is well exposed in the east of the mining area and occurs in the drill cores, and a second phase characterized by fewer phenocrysts resulting in a medium-grained granite porphyry (Fig. 4b, d), which has a small outcropping in the northwest of the deposit but mostly occurs in

) drill cores. The coarse-grained granite porphyry has a ﬂeshy pink color (Fig. 4a). The phenocrysts are 0.1–1-cm-sized quartz (30– 35%), and 0.2–1.5 cm-sized alkali feldspar and plagioclase crystals continued ( (55–65%) with minor 0.1–0.5-cm-sized biotite (5%) and magnetite grains (1%). The quartz has corroded edges and forms aggregates, Shangfanggou Mo Syenogranite porphyry Nannihu Mo Monzogranite, Granodiorite K: K-feldspar, quartz, biotite, molybdenite, pyrite Deposit Metallogenic belt Metals Host rocks Alteration/mineralization Age (Ma) Reference Donggou Mo Granite porphyry K: K-feldspar, quartz, molybdenite, pyrite Dasuji Northern North China Craton Mo-Cu Quartz porphyry Caosiyao Mo Granite porphyry K: K-feldspar, quartz, biotite, molybdenite, pyrite

Table 1 while some of the K-feldspar has partially been altered to clay 286 H. Wu et al. / Journal of Asian Earth Sciences 127 (2016) 281–299

Fig. 2. Schematic geologic map of the Caosiyao porphyry Mo deposit. Modified from Nie et al. (2012) and NGIHBGMD (2013). minerals. The groundmass mainly consists of feldspar and quartz sealed using an oxygen-propane torch. After 15 min ultrasonic with a micrographic texture (Fig. 4c). The medium-grained granite oscillating the tube was then placed in a stainless-steel jacket porphyry is grey to brown in color (Fig. 4b). The phenocrysts are and heated for 48 h at 230 °C. Upon cooling, the bottom part of 0.2–5-mm-sized quartz (35–40%), 0.1–2-mm-sized alkali feldspar the tube was kept frozen and the neck of the tube was broken. and plagioclase grains (50–63%) with minor amphibole (3%), bio- An electrothermal steamer was employed for Os in situ distillation tite (2%), and magnetite (1%). The quartz is fractured and has in Carius tube. The neck of the original Carius tube was sealed with absorbed margins, while the K-feldspar has partially been altered a stretchy rubber head through which a pair of Teflon tubes to argillic minerals. The groundmass mainly consists of feldspar pierced, serving as inlet and outlet for clean air and OsO4, respec- and quartz with a micrographic texture (Fig. 4d). Two samples tively. OsO4 evaporated was trapped in 5 ml of Milli-Q (MQ) water. respectively collected from the two phases of the granite porphyry Usually 1/50–1/20 part of the residual Re-bearing solution after Os were selected for zircon U–Pb dating and Hf isotopic analyses. Rock distillation was enough for Re measurement. BioRad AG-1X8 resin chips of the granite porphyry with the least alteration were was employed for Re separation. Os and Re isotope ratios were crushed to a size of 200 mesh for major and trace element analyses. determined using an inductively coupled plasma mass spectrometer (Element ICP-MS). The molybdenite standard GBW04435 (HLP) 4.2. Molybdenite Re–Os dating used in this study yielded a mean value of 220.0 ± 4.1 Ma. Blanks for Re and Os used in this study were 0.65 ± 0.23 pg and Re–Os isotope analyses of group (1) samples (disseminated 0.05 ± 0.003 pg, respectively. molybdenite) were carried out at the Re–Os Laboratory, National The Re–Os isochron age was calculated using the least-squares Research Center of Geoanalysis, Chinese Academy of Geological method of York (1969), as implemented in the ISOPLOT 2.49 pro- Sciences. The detailed analytical procedures were described by gram (Ludwig, 2001). The decay constant used in the age calcula- 187 À11 À1 Du et al. (1994, 2004) and Stein et al. (2001). The molybdenite tion is k Re = 1.666 Â 10 year (Smoliar et al., 1996). 187 standard GBW04435 (HLP) used in this study gave a mean value Uncertainty in the Re–Os model ages includes 1.02% in the Re of 222.1 ± 3.2 Ma compared with the certified value of decay constant and in Re and Os concentrations which comprises 221.4 ± 5.6 Ma (Du et al., 2004), which is identical to that of HLP- weighing error for both spike and sample, uncertainty in spike 5 (221.5 ± 0.3 Ma, Stein et al., 1997; 220.52 ± 0.24 Ma, Selby and calibration and mass spectrometry analytical error. Creaser, 2004). Blanks used in this study were 2.2 ± 1.1 pg for Re and 0.12 pg ± 0.01 pg for Os. 4.3. Zircon U–Pb dating and Lu–Hf isotope analyses The group (2) veinlet-type molybdenite samples were analyzed at Institute of Geology and Geophysics, Chinese Academy of Zircon U–Pb analysis was performed at the Laser Ablation Sciences (IGGCAS). The analytical procedures were described by Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) Jin et al. (2013) and are briefly summarized below. The suitable microanalysis laboratory, which is affiliated with the State Key amount of weighed sample was loaded in a Carius tube. The mixed Laboratory of Geological Processes and Mineral Resources, China 185 190 Re and Os spike, 3 ml of 10 M HCl and 6 ml of 15 M HNO3 University of Geosciences, Beijing. Laser sampling was performed were added while the bottom part of the tube was frozen at À80 using a Coherent’s GeoLasPro-193 nm system. A Thermo Fisher to À50 °C in an ethanol-liquid nitrogen slush, and the top was X-Series 2 ICP-MS instrument was used to acquire ion signal H. Wu et al. / Journal of Asian Earth Sciences 127 (2016) 281–299 287

Fig. 3. Photographs of molybdenite ores (a–f) and photomicrographs of ore minerals (g and h) from the Caosiyao porphyry Mo deposit. Disseminated molybdenite (a) and stockwork molybdenite (b) in the granite porphyry, (c) stockwork molybdenite in Archean metamorphic rocks, (d–f) veinlet-type molybdenite ores in Archean metamorphic rocks. 288 H. Wu et al. / Journal of Asian Earth Sciences 127 (2016) 281–299

Fig. 4. Photographs of the coarse-grained (a) and medium-grained granite porphyry (b) from the Caosiyao porphyry Mo deposit and their corresponding photomicrographs (c and d).

intensities. Helium was applied as a carrier gas. Argon was used as fractionation coefficient of Yb, and finally deducting the contribu- the make-up gas and mixed with the carrier gas. All data were tion of 176Yb to 176Hf. The 176Yb/172Yb value of 0.5887 and mean acquired from zircon samples in single spot ablation mode with bYb value obtained during Hf analysis on the same spot were a spot size of 32 lm and 6 Hz frequency. The SRM610 standard applied for the interference correction of 176Yb on 176Hf (Iizuka from the U.S. National Institute of Standards and Technology (NIST) and Hirata, 2005; Wu et al., 2006). During analyses, the 176Hf/177Hf was used to optimize the ICP-MS instrument, and as an external ratios of the double standard zircon GJ-1 and Mud Tank were standard for determination of trace elements. Zircon 91500 was 0.282019 ± 9 (2r, n = 41) and 0.282519 ± 7 (2r, n = 42) respec- used as an external standard for U–Th–Pb isotopic ratios tively, similar to the commonly accepted 176Hf/177Hf ratios of (Wiedenbeck et al., 1995, 2004). Meanwhile zircon Mud Tank 0.281999 ± 6 (2r, n = 5) and 0.282507 ± 6 (2r, n = 5) measured was used as a monitoring standard for each analysis (Black and using the solution method (Woodhead et al., 2004; Wu et al., C Gulson, 1978). Time-dependent drifts of U–Th–Pb isotopic ratios 2006; Zeh et al., 2007). The notations of eHf, fLu/Hf, TDM and TDM were corrected using a linear interpolation (with time) for every are defined as in Yang et al. (2006). five analyses according to the variations of the 91500 standard (i.e., 2 zircons 91500 + 5 samples + 2 zircons 91500). Each analysis 4.4. Major and trace elements included a background acquisition of approximately 20 s (gas blank) followed by 50 s of data acquisition from the sample. Off- Major element oxides were analyzed using fused glass discs line selection and integration of background and analyte signals, with a Phillips PW 1500 X-ray fluorescence spectrometer at as well as time-drift correction and quantitative calibration for IGGCAS. FeO concentrations were determined using a conventional trace element analyses and U–Pb dating were performed using titration procedure. The precision and accuracy of the major ele- ICPMSDataCal (Liu et al., 2008). The ISOPLOT 3.00 program ment data as determined with the Chinese whole-rock granite (Ludwig, 2003) was used for reduction and to produce the Concor- standard GSR-1 (Xie et al., 1985) are <5% and 5% (2r), respec- dia diagram. tively (Zhou et al., 2002). Trace elements were analyzed at the Lu–Hf isotope analyses were carried out at the MC-ICPMS labo- State Key Laboratory of Geological Processes and Mineral ratory of IGGCAS. A Neptune multi-collector (MC)-ICPMS was used Resources, China University of Geosciences, Wuhan. for determination of Lu-Hf isotopes with a 193 nm excimer ArF laser-ablation system (GeoLas Plus) attached. The detailed analyt- 5. Analytical results ical procedures have been described by Xie et al. (2008). The iso- baric interference of 176Lu on 176Hf is negligible due to the 5.1. Molybdenite Re–Os dating extremely low 176Lu/177Hf in zircon (normally < 0.002). The interference of 176Yb on 176Hf was calculated by measuring the mean Analyses of 11 molybdenite samples from the Caosiyao Mo 173Yb/171Yb ratio of the individual spot, and then calculating the deposit are reported in Table 2. Five disseminated molybdenite H. Wu et al. / Journal of Asian Earth Sciences 127 (2016) 281–299 289

Table 2 Re and Os isotopic data for molybdenite in the Caosiyao porphyry Mo deposit.

Sample no. Sample weight (g) Total Re (±2r) (ppm) 187Re (±2r) (ppm) 187Os (±2r) (ppb) Model age (±2r) (Ma) CS2 disseminated molybdenite CS2-43 0.02246 6.220 ± 0.042 3.910 ± 0.026 9.63 ± 0.06 147.7 ± 2.0 CS2-44 0.03088 10.37 ± 0.10 6.515 ± 0.063 16.05 ± 0.11 147.7 ± 2.3 CS2-6 0.03057 7.719 ± 0.061 4.852 ± 0.038 12.07 ± 0.07 149.1 ± 2.1 CS2-2 0.03045 13.60 ± 0.12 8.550 ± 0.076 21.53 ± 0.21 150.9 ± 2.5 CS2-45 0.03043 5.467 ± 0.043 3.436 ± 0.027 8.615 ± 0.06 150.3 ± 2.2 CS3 veinlet-type molybdenite CS3-22 0.102 6.709 ± 0.048 4.217 ± 0.030 10.23 ± 0.06 145.5 ± 2.0 CS3-41 0.100 11.87 ± 0.091 7.463 ± 0.058 18.24 ± 0.13 146.5 ± 2.1 CS3-20 0.134 9.059 ± 0.071 5.694 ± 0.045 13.99 ± 0.09 147.3 ± 2.1 CS3-4 0.183 6.735 ± 0.075 4.233 ± 0.047 10.35 ± 0.07 146.6 ± 2.4 CS3-3 0.134 9.148 ± 0.069 5.750 ± 0.043 13.98 ± 0.09 145.8 ± 2.1 CS3-1 0.189 6.722 ± 0.049 4.225 ± 0.030 10.38 ± 0.07 147.3 ± 2.0

Decay constant: k187Re = 1.666 Â 10À11 yearÀ1 (Smoliar et al., 1996). Uncertainties are absolute at 2r with error on Re and 187Os contents and the uncertainty in the 187Re decay constant. samples yielded model ages ranging from 147.7 ± 2.3 to with a well-constrained 187Re–187Os isochron age of 146.9 ± 150.9 ± 2.5 Ma, with a 187Re–187Os isochron age of 149.5 ± 5.3 Ma 3.1 Ma (Fig. 5c) and a weighted average age of 146.5 ± 0.8 Ma (Fig. 5a) and a weighted average age of 149.0 ± 1.8 Ma (Fig. 5b). (Fig. 5d). The intercept with the 187Os axis for both plots is nearly Six veinlet-type molybdenite samples yielded relatively narrow zero within the range of uncertainty, which is expected because ranges of Re–Os model ages from 145.5 ± 2.0 to 147.3 ± 2.1 Ma, molybdenite contains little or no non-radiogenic 187Os. This

Fig. 5. Re–Os isochron diagrams and weighted average model age diagrams for ﬁve disseminated molybdenite samples (a and b), and six veinlet-type molybdenite samples (c and d). 290 H. Wu et al. / Journal of Asian Earth Sciences 127 (2016) 281–299 indicates that the model age determined with the contents of 187Re Zircons from the medium-grained granite porphyry are of smal- and 187Os in molybdenite is reliable (Stein et al., 1997; Selby and ler length, ranging from 50 to 150 lm. Most of the zircons have Creaser, 2001), and therefore the age can be calculated with the aspect ratios of 1:1–2:1. In the CL images (Fig. 6b), they also have equation t = (1/k)ln(1+187Os/187Re). relatively dark CL brightness, obvious oscillatory zones and dark rims with high Th/U ratios (0.50–1.00; Table 3), also indicative of 5.2. Zircon cathodoluminescence (CL) imaging and U–Pb dating a magmatic origin. Sixteen analyses form a coherent group with a well-constrained concordant 206Pb/238U age of 149.0 ± 2.2 Ma Zircons from the coarse-grained granite porphyry are 80– (Fig. 7c), in good accordance with the 206Pb/238U weighted mean 300 lm in length. Most of the zircons have aspect ratios of 1:1– age of 149.0 ± 2.1 Ma (Fig. 7d), representing the formation age of 3:1. In the CL images (Fig. 6a), they generally have relatively dark the granite porphyry. CL brightness showing obvious oscillatory zones and dark rims, most with high Th/U ratios (0.52–1.63; Table 3), indicating a mag- 5.3. Zircon Hf isotopic composition matic origin. Fourteen analyses form a coherent group with a well- constrained concordant 206Pb/238U age of 149.8 ± 2.4 Ma (Fig. 7a) Zircons from both phases of the granite porphyry have similar and a 206Pb/238U weighted mean age of 149.9 ± 2.4 Ma (Fig. 7b), Hf isotopic compositions. Zircons from the coarse-grained granite which is interpreted to represent the formation age of the granite porphyry have initial 176Hf/177Hf ratios ranging from 0.282160 to porphyry. 0.282334, eHf(t) values between À12.2 and À18.3 (t = 150 Ma),

Fig. 6. Cathodoluminescence (CL) images of zircons from the granite porphyry in the Caosiyao porphyry Mo deposit. H. Wu et al. / Journal of Asian Earth Sciences 127 (2016) 281–299 291

Table 3 Zircon U-Pb data of the granite porphyry in the Caosiyao porphyry Mo deposit.

Spots U Th Th/U Isotope ratios Age (ppm) (ppm) 207Pb/206Pb 1r (%) 207Pb/235U1r (%) 206Pb/238U1r (%) Pb207/Pb206 1r (%) Pb207/U235 1r (%) Pb206/U238 1r (%) CS2-3 Coarse-grained granite porphyry CS2-3@02 476 461 0.97 0.048229 0.005 0.154322 0.013 0.023482 0.0005 109.4 207.4 145.7 11.3 149.6 3.4 CS2-3@03 316 321 1.02 0.046121 0.007 0.147815 0.018 0.023108 0.0008 400.1 À83.3 140.0 16.0 147.3 4.7 CS2-3@04 624 347 0.56 0.04864 0.005 0.160431 0.016 0.023441 0.0006 131.6 222.2 151.1 13.7 149.4 3.8 CS2-3@06 174 106 0.61 0.05223 0.011 0.159698 0.023 0.023394 0.0011 294.5 429.6 150.4 20.5 149.1 6.9 CS2-3@08 45 74 1.63 0.051664 0.015 0.1666 0.043 0.023516 0.0015 333.4 494.4 156.5 37.2 149.8 9.5 CS2-3@09 68 56 0.83 0.072405 0.025 0.167591 0.054 0.023536 0.0016 998.2 749.2 157.3 47.4 150.0 9.8 CS2-3@15 505 263 0.52 0.05284 0.005 0.174065 0.015 0.023498 0.0007 320.4 220.3 162.9 13.3 149.7 4.2 CS2-3@16 2052 630 0.31 0.048299 0.005 0.161819 0.015 0.023584 0.0006 122.3 201.8 152.3 13.2 150.3 3.8 CS2-3@18 114 92 0.81 0.052841 0.010 0.157838 0.020 0.023462 0.0009 320.4 374.0 148.8 17.6 149.5 5.9 CS2-3@20 875 504 0.58 0.051084 0.004 0.167262 0.011 0.023658 0.0006 255.6 161.1 157.0 9.5 150.7 3.7 CS2-3@21 473 403 0.85 0.052579 0.005 0.174328 0.016 0.023732 0.0005 309.3 229.6 163.2 13.7 151.2 3.5 CS2-3@22 209 185 0.88 0.057264 0.009 0.172471 0.020 0.023546 0.0009 501.9 353.7 161.6 17.3 150.0 5.8 CS2-3@23 69 77 1.13 0.047703 0.012 0.169567 0.038 0.023623 0.0015 83.4 507.3 159.0 33.4 150.5 9.2 CS2-3@24 257 289 1.13 0.054679 0.006 0.174894 0.017 0.023491 0.0006 398.2 216.6 163.7 14.4 149.7 3.6 CS8-4 Medium-grained granite porphyry CS8-4@01 456 238 0.52 0.048539 0.006 0.15919 0.018 0.023508 0.0008 124.2 270.3 150.0 15.6 149.8 4.9 CS8-4@05 155 117 0.76 0.051307 0.010 0.163163 0.021 0.023746 0.0011 253.8 385.1 153.5 18.3 151.3 6.9 CS8-4@06 295 169 0.57 0.048308 0.007 0.157285 0.021 0.023227 0.0008 122.3 305.5 148.3 18.5 148.0 5.0 CS8-4@07 154 153 1.00 0.054485 0.009 0.166704 0.020 0.022982 0.0009 390.8 329.6 156.6 17.2 146.5 5.6 CS8-4@09 112 79 0.71 0.05281 0.010 0.155858 0.024 0.023353 0.0014 320.4 385.1 147.1 21.4 148.8 8.7 CS8-4@11 175 173 0.99 0.054264 0.010 0.161206 0.025 0.023468 0.0011 383.4 366.6 151.8 21.9 149.5 6.7 CS8-4@12 68 64 0.95 0.061548 0.013 0.164049 0.026 0.023478 0.0010 657.4 470.3 154.2 23.1 149.6 6.4 CS8-4@13 330 261 0.79 0.051205 0.006 0.16524 0.014 0.023474 0.0007 250.1 248.1 155.3 12.4 149.6 4.2 CS8-4@14 253 126 0.50 0.055076 0.017 0.160664 0.036 0.023657 0.0009 416.7 572.2 151.3 31.3 150.7 5.9 CS8-4@15 592 319 0.54 0.048281 0.004 0.157691 0.011 0.023348 0.0005 122.3 161.1 148.7 9.5 148.8 2.9 CS8-4@16 337 223 0.66 0.050255 0.005 0.159431 0.013 0.023391 0.0005 205.6 227.8 150.2 11.7 149.1 3.3 CS8-4@18 192 150 0.78 0.052258 0.009 0.163531 0.021 0.022845 0.0011 298.2 351.8 153.8 18.6 145.6 6.8 CS8-4@19 877 557 0.64 0.047623 0.003 0.156578 0.009 0.02328 0.0004 79.7 153.7 147.7 8.1 148.4 2.5 CS8-4@20 311 195 0.63 0.049874 0.005 0.157333 0.012 0.023479 0.0006 190.8 207.4 148.4 10.4 149.6 3.5 CS8-4@21 182 106 0.58 0.05549 0.007 0.172417 0.016 0.023291 0.0006 431.5 264.8 161.5 13.9 148.4 4.1 CS8-4@22 232 130 0.56 0.054645 0.007 0.161313 0.016 0.023568 0.0006 398.2 276.8 151.9 14.2 150.2 3.8

C and crustal model ages (TDM) ranging from 1969 Ma to 2345 Ma. coarse-grained granite porphyry form a coherent group and show Zircons from the medium-grained granite porphyry show initial a well-constrained concordant 206Pb/238U age of 149.8 ± 2.4 Ma 176 177 206 238 Hf/ Hf ratios ranging from 0.282180 to 0.282310, eHf(t) values (Fig. 7a), in accordance with the Pb/ U weighted mean age C between À13.1 and À17.7 (t = 149 Ma), and TDM ranging from of 149.9 ± 2.4 Ma (Fig. 7b). Sixteen magmatic zircons from the 2019 Ma to 2302 Ma (Table 4). medium-grained granite porphyry also form a coherent group with a well-constrained concordant 206Pb/238U age of 149.0 ± 2.2 Ma 5.4. Major and trace element composition (Fig. 7c), in almost perfect accordance with the 206Pb/238U weighted mean age of 149.0 ± 2.1 Ma (Fig. 7d). The two phases of The major and trace element analytical results are listed in the Mo mineralization-related granite porphyry show almost iden- Table 5. The SiO2 contents of the coarse-grained granite porphyry tical zircon U–Pb ages, which are within the analytical error, indi- range from 71.52 to 72.08 wt%, K2O ranges from 5.20 to 5.67 wt cating their contemporaneous emplacement at 149–150 Ma. %, and Na2O from 2.85 to 3.09 wt%. The medium-grained granite Moreover, these two phases show a gradual transition, rather than porphyry is more siliceous, with SiO2 contents ranging from abrupt contact relationships as observed from drill cores 73.48 to 74.10 wt%, K2O from 5.93 to 6.27 wt%, and Na2O from (NGIHBGMD, 2013). Thus, it is suggested that these two phases 1.94 to 2.68 wt%. of the granite porphyry were derived from continuous differentia- Chondrite-normalized REE patterns of the coarse-grained gran- tion of the same magma during the Late Jurassic. The U–Pb ages ite porphyry show moderate fractionation between LREE and HREE indicate that the coarse-grained porphyry may have crystallized with negative Eu anomalies, while the medium-grained granite somewhat earlier than the medium-grained variety. porphyry samples show more obvious negative Eu anomalies and Eleven samples representative of disseminated (n = 5) and moderate fractionation between LREE and HREE (Fig. 8a). On the veinlet-hosted (n = 6) molybdenite yielded 187Re–187Os isochron primitive-mantle (PM) normalized spider plots, both phases of ages of 149.5 ± 5.3 Ma and 146.9 ± 3.1 Ma (Fig. 5a, c), respectively. the granite porphyry show relatively obvious negative Ba, Sr, P, The observation that the veinlet-hosted Mo mineralization and Ti anomalies, and positive U and K anomalies (Fig. 8b). (146.9 ± 3.1 Ma) appears to be slightly younger than the disseminated molybdenite (149.5 ± 5.3 Ma) is consistent with the 6. Discussion observed paragenetic sequence, in which the former postdated the latter. However, the two groups of isochron ages, which were 6.1. Ages of the host granite porphyry and mineralization obtained in different laboratories, are almost identical within the analytical error, suggesting that they are products of one mag- As mentioned above, based on the mineral assemblages and matic–hydrothermal event, during which the disseminated molyb- textures, two different phases (coarse-grained and medium- denite was deposited slightly earlier than the veinlet deposits. grained) can be distinguished within the Mo mineralization- Moreover, the molybdenite Re–Os data (147–149 Ma) are similar related granite porphyry. Fourteen magmatic zircons from the to the zircon U–Pb ages of the host granite porphyry 292 H. Wu et al. / Journal of Asian Earth Sciences 127 (2016) 281–299

Fig. 7. Zircon 207Pb/235U–206Pb/238U Concordia plots and 206Pb/238U weighted mean age diagrams of the granite porphyry in the Caosiyao porphyry Mo deposit.

(149–150 Ma), indicating that a Mo mineralization event occurred 6.2. Geochemical features and source of the host granitoids in Caosiyao during 147–150 Ma in the Late Jurassic. An earlier study by Nie et al. (2013) gave four molybdenite Based on normative quartz and feldspar proportions derived model Re–Os ages ranging from 128.6 ± 2.4 Ma to 131.9 ± 2.3 Ma from the CIPW-norm (Fig. 9a), the host granite porphyry samples for the Caosiyao deposit, but the authors did not clearly indicate from the Caosiyao Mo deposit plot in the monzogranite–syenogra ore-related intrusions and their isotopic ages. Li et al. (2012) men- nite ﬁeld, which is in accordance with the porphyry’s petrographic tioned zircon ages of 131–134 Ma for one granite porphyry from name based on mineral components of the rock specimens. A dia- the Caosiyao deposit, but did not provide the data used to constrain gram of K2O vs. SiO2 (Fig. 9b) shows that the samples are highly these ages. Regional information suggests that the Caosiyao Mo enriched in potassium, belonging to the shoshonite series. In a plot mineralization in the Late Jurassic was not single in North China of (Na2O+K2O–CaO) vs. SiO2 (Fig. 9c), the samples are alkali– and its adjacent areas. The mineralization event of 147–150 Ma calcic. The Fe2O3/FeO vs. SiO2 diagram in Fig. 9d, together with in the Caosiyao deposit is almost simultaneous with that of the the presence of magnetite in the granite porphyry, indicate that giant Chalukou porphyry Mo deposit (2.46 Mt Mo metal; Meng samples are relatively oxidized, similar to the host granitoids of et al., 2011)at147 Ma (Li et al., 2014), and the giant Diyanqi- many other porphyry Mo deposits worldwide. These oxidized namu porphyry Mo deposit (0.78 Mt Mo metal; Leng et al., granitoids are commonly associated with important metallic 2015)at156 Ma (Leng et al., 2015), suggesting that a large- mineral deposits where the ore minerals are present as sulﬁdes, scale Mo mineralization event affected the northern NCC and its especially Mo. For example, 98% of molybdenum in Japan occurs adjacent areas in the Late Jurassic. Thus, we suggest that the in oxidized granitoids (Ishihara and Imai, 2014). large-scale Mo mineralization of the Caosiyao deposit occurred The host granite porphyry shows enrichment in U and K, and mainly in the Late Jurassic (i.e., 147–150 Ma), although a later depletion in Ba, Sr, P, Eu, and Ti (Fig. 8a, b), suggesting strong frac- magmatic–hydrothermal event at 130 Ma resulting in local Mo tional crystallization of plagioclase, biotite, and accessory minerals. mineralization cannot be ruled out. This, together with high SiO2 contents and high DI values of 89–92, H. Wu et al. / Journal of Asian Earth Sciences 127 (2016) 281–299 293

Table 4 Hf isotopic data of zircons from the granite porphyry in the Caosiyao porphyry Mo deposit.

176 177 176 177 176 177 a a C a Spots Lu/ Hf Hf/ Hf 2r Hf/ Hfi eHf(t) 2r TDM (Ma) TDM (Ma) CS2-3 Coarse-grained granite porphyry CS2-3-1-2 0.000900 0.282202 0.000022 0.282199 À17.0 0.77 1478 2263 CS2-3-1-3 0.000698 0.282240 0.000025 0.282238 À15.7 0.88 1418 2181 CS2-3-1-4 0.000825 0.282248 0.000022 0.282245 À15.4 0.77 1412 2162 CS2-3-1-6 0.000609 0.282335 0.000025 0.282334 À12.2 0.90 1282 1969 CS2-3-1-8 0.000752 0.282273 0.000026 0.282271 À14.5 0.92 1374 2107 CS2-3-1-9 0.000703 0.282243 0.000022 0.282241 À15.5 0.78 1414 2173 CS2-3-1-15 0.001182 0.282200 0.000021 0.282197 À17.0 0.75 1491 2266 CS2-3-1-16 0.001498 0.282164 0.000023 0.282160 À18.3 0.82 1555 2345 CS2-3-1-18 0.000463 0.282249 0.000021 0.282248 À15.3 0.74 1396 2159 CS2-3-1-20 0.000918 0.282245 0.000023 0.282242 À15.4 0.83 1419 2167 CS2-3-1-21 0.000959 0.282172 0.000021 0.282169 À18.0 0.75 1522 2328 CS2-3-1-22 0.000757 0.282212 0.000025 0.282210 À16.6 0.87 1459 2241 CS2-3-1-23 0.000441 0.282222 0.000021 0.282221 À16.2 0.75 1432 2218 CS2-3-1-24 0.000868 0.282254 0.000021 0.282252 À15.1 0.76 1404 2148 CS8-4 Medium-grained granite porphyry CS8-4-1 0.001024 0.282313 0.000028 0.282310 À13.1 0.98 1328 2019 CS8-4-5 0.000835 0.282285 0.000045 0.282283 À14.0 1.59 1360 2078 CS8-4-6 CS8-4-7 0.000902 0.282238 0.000031 0.282235 À15.8 1.11 1428 2186 CS8-4-9 0.001563 0.282185 0.000030 0.282180 À17.7 1.05 1529 2302 CS8-4-11 0.000830 0.282263 0.000022 0.282260 À14.8 0.77 1391 2129 CS8-4-12 0.000442 0.282257 0.000022 0.282256 À15.0 0.79 1385 2141 CS8-4-13 0.002457 0.282208 0.000053 0.282202 À16.9 1.87 1532 2249 CS8-4-14 0.000873 0.282231 0.000025 0.282229 À15.9 0.89 1436 2198 CS8-4-15 0.000946 0.282311 0.000023 0.282308 À13.2 0.81 1328 2024 CS8-4-16 0.000736 0.282254 0.000021 0.282252 À15.1 0.76 1400 2149 CS8-4-18 0.001058 0.282206 0.000031 0.282203 À16.9 1.11 1478 2256 CS8-4-19 0.001129 0.282289 0.000023 0.282286 À14.0 0.81 1365 2072 CS8-4-20 0.001128 0.282275 0.000027 0.282272 À14.4 0.94 1385 2102 CS8-4-21 0.000879 0.282217 0.000028 0.282215 À16.5 1.00 1456 2230 CS8-4-22 0.000813 0.282263 0.000020 0.282261 À14.8 0.72 1389 2127

176 177 176 177 176 177 176 177 TDM =1/k Â ln{1 + [( Hf/ Hf)S À ( Hf/ Hf)DM]/[( Lu/ Hf)S À ( Lu/ Hf)DM]}. C 176 177 176 177 176 177 176 177 TDM =1/k ln{1 + [( Hf/ Hf)S,t À ( Hf/ Hf)DM,t]/[( Lu/ Hf)C À ( Lu/ Hf)DM]} + t. The 176Hf/177Hf and 176Lu/177Hf ratios of chondrite and depleted mantle at the present are 0.282772 and 0.0332, 0.28325 and 0.0384, respectively (Blichert-Toft and Albarède, À11 À1 176 177 1997; Grifﬁn et al., 2000). k = 1.867 Â 10 a (Soderlund et al., 2004). ( Lu/ Hf)C = 0.015, t = crystallization age of zircon. a 176 177 176 177 kt 176 177 176 177 kt eHf(t) = 10,000{[( Hf/ Hf)S À ( Lu/ Hf)S Â (e À 1)]/[( Hf/ Hf)CHUR,0 À ( Lu/ Hf)CHUR Â (e À 1)] À 1}.

indicates a high degree of differentiation of the granite magma. On Xilamulun Mo–Cu metallogenic belt (Jiguanshan, Chehugou, the plot of t–eHf(t)(Fig. 10), the magmatic zircons from the granite Gangzi, Xiaodonggou, Aolunhua, and Banlashan deposits), the porphyry show a spread of eHf(t) values expected for the mafic Jilin–Heilongjiang (Jihei; Daheishan and Luming deposits), and lower crust, indicative of a magma source derived from the lower the Da–Hinggan Mo–Cu metallogenic belt (Chalukou and Diyanqi- crust. Thus, it is suggested that the granite porphyry in the Cao- namu deposits) (Fig. 1a and Table 1), indicating the considerable siyao Mo deposit was derived from partial melting of old lower Mo metallogenic potential of the northern NCC and its adjacent crust. areas. The northern NCC and its adjacent areas, situated between the 6.3. Implications for ore genesis and a genetic model for the Caosiyao Paleo-Asian Ocean and the western Circum-Pacific tectonic regime, porphyry Mo deposit were mainly affected by the Paleo-Asian Ocean tectonic regime before the middle Mesozoic. Since the Jurassic, this region entered A favorable source region with high contents of Mo is important into an intraplate orogeny stage, linked to the Paleo-Pacific tec- for the formation of Mo-bearing magma (Hou et al., 2015). Most tonic regime, during which intense tectonic–magmatic activities large Mo deposits occur within or along the margin of ancient con- were responsible for large-scale Mo mineralization (Davis et al., tinents, and are genetically related to Mesozoic–Cenozoic tectonic– 2004; Fan et al., 2003; Li, 2006). Recent geochemical and geophys- magmatic activities. Good examples include the porphyry Mo ical data indicate that westward subduction of the Paleo-Pacific deposits in the Colorado Mo belt represented by the Climax and plate may have affected the Zhangjiakou and Hohhot district Henderson mines (Seedorff and Einaudi, 2004a, 2004b; Wallace (Goldfarb et al., 2014; Zhu et al., 2011, 2012). The newly discovered et al., 1978; White et al., 1981), and the Qinling Mo metallogenic Caosiyao Mo mineralization at 147–150 Ma, located east of Hohhot belt in the southern part of the NCC represented by Jinduicheng, in the northern NCC, is a good example for a Paleo-Pacific Shijiawan, Yuchiling, Leimengou, Dongou, Nannihu and Shang- subduction-related magmatic–hydrothermal event. During the fanggou deposits (Cao et al., 2015; Li et al., 2006; Ye et al., 2006; Late Jurassic, the Caosiyao region was affected by the transition H.J. Zhao et al., 2010; Zhu et al., 2008, Fig. 1a), as well as Mo occur- from Indosinian–Yanshanian tectonism to far-field tectonics rences in the northern part of the NCC such as the Dazhuangke, related to the Paleo-Pacific subduction. During this period, large– Dacaoping, Sadaigoumen, and Lanjiagou deposits (Duan et al., scale extension occurred and previously formed, deep-seated faults 2007; Han et al., 2009; Huang et al., 1996; Wei et al., 2013). In were reactivated, resulting in intense mantle–crust interaction and recent years, additional metallogenic belts with Mo as the major material exchange, as well as large–scale partial melting of the metal resource have been discovered in the northern margin of lower crust, which was responsible for the large-scale Mo mineral- the NCC and its adjacent areas to the north (CAOB), including the ization of the region (Hou et al., 2015; Zhai et al., 2003, 2004). 294 H. Wu et al. / Journal of Asian Earth Sciences 127 (2016) 281–299

Table 5 Major and trace element data of the granite porphyry in the Caosiyao porphyry Mo deposit.

Sample no. CS2-3-1 CS2-3-4 CS2-3-5 CS8-3 CS8-4 CS8-5 Coarse-grained granite porphyry Medium-grained granite porphyry Major elements (wt%)

SiO2 71.64 71.52 72.08 74.1 73.48 73.6

TiO2 0.31 0.32 0.31 0.18 0.18 0.18

Al2O3 13.96 14.52 13.84 13.49 13.75 13.44

Fe2O3 0.97 0.98 0.76 0.51 0.4 0.35 FeO 1.15 1.04 1.14 0.85 0.81 1.1 MnO 0.06 0.04 0.04 0.03 0.03 0.02 MgO 0.48 0.43 0.4 0.24 0.21 0.29 CaO 1.11 1.09 1.08 0.71 0.74 0.67

Na2O 3.08 3.09 2.85 2.6 2.68 1.94

K2O 5.2 5.67 5.51 6.02 5.93 6.27

P2O5 0.13 0.12 0.11 0.05 0.04 0.05 LOI 1.5 0.88 1.36 1.58 1.5 1.94

Na2O+K2O 8.28 8.76 8.36 8.62 8.61 8.21

Fe2O3/FeO 0.84 0.94 0.67 0.6 0.49 0.32 Total 99.58 99.7 99.48 100.36 99.75 99.85 r 2.37 2.68 2.38 2.38 2.42 2.19 DI 89.04 89.46 89.57 92.44 92.29 91.24 Trace elements (ppm) Rb 335 340 306 215 261 235 Ba 236 225 266 668 591 813 Th 28.63 28.69 29.11 21.65 21.46 20.10 U 6.57 6.28 8.13 4.05 4.15 4.61 Ta 2.03 2.07 1.81 2.54 2.40 2.30 Sr 75 70 69 248 212 233 Zr 131.36 131.69 124.11 173.41 166.98 174.48 Hf 4.46 4.65 4.34 5.04 4.90 4.72 La 54.71 51.32 55.13 53.02 56.14 52.07 Ce 111.62 102.91 110.17 102.03 105.45 102.45 Pr 12.34 11.74 12.65 10.85 11.22 11.22 Nd 44.72 42.32 44.47 37.43 39.06 39.44 Sm 9.29 8.89 8.89 6.80 7.23 7.10 Eu 0.53 0.54 0.58 1.01 1.03 1.09 Gd 7.00 7.15 6.88 4.95 5.84 5.33 Tb 0.95 0.98 1.00 0.76 0.86 0.82 Dy 5.27 5.40 5.44 4.33 4.71 4.29 Ho 0.88 0.96 0.93 0.76 0.83 0.77 Er 2.41 2.51 2.45 2.06 2.31 2.14 Tm 0.37 0.40 0.37 0.33 0.36 0.33 Yb 2.18 2.37 2.24 2.05 2.14 1.95 Lu 0.31 0.31 0.31 0.29 0.30 0.29 PY 27.83 28.60 28.70 24.18 27.93 24.92 REE 253 238 252 227 237 229 dEu 0.20 0.21 0.23 0.53 0.49 0.54

(La/Yb)N 16.90 14.58 16.59 17.42 17.67 18.04

(La/Sm)N 3.70 3.63 3.90 4.91 4.88 4.61

(Gd/Yb)N 2.59 2.43 2.48 1.95 2.20 2.21

Notes: Major elements (wt%) were analyzed by XRF; LOI = loss on ignition. DI = Qz + Or + Ab + Ne + Lc + Kp. Trace elements (ppm) were analyzed by ICP-MS; dEu = EuN/ 1/2 (SmN Â GdN) ; N = chondrite-normalized concentrations (Boynton, 1984).

Fig. 8. Chondrite-normalized REE patterns (a) and primitive mantle normalized trace element spider diagrams (b) for the granite porphyry in the Caosiyao porphyry Mo deposit. Primitive mantle values are from Sun and McDonough (1989); chondrite-normalized values are from Boynton (1984). H. Wu et al. / Journal of Asian Earth Sciences 127 (2016) 281–299 295

Fig. 9. QAP (a), K2O vs. SiO2 (b), (Na2O+K2O–CaO) vs. SiO2 (c) and Fe2O3/FeO vs. SiO2 (d) plots of the granite porphyry in the Caosiyao porphyry Mo deposit.

A Mo-enriched magma is essential for subsequent formation of porphyry Mo deposits. Mo is an incompatible element and is usually associated with alkali-rich felsic intrusions with low iron and titanium contents that are highly oxidized (Candela and Holland, 1986; Audétat, 2010; Audétat et al., 2011). The presence of high levels of oxygen and alkali elements can lower the solidus temperature (Glyuk and Anfilogov, 1973), prolong the fractionation process, and enhance the miscibility of Mo in the melt (Isuk and Carman, 1981; Štemprok, 1975), leading to an enrichment of Mo in the residual melt and subsequent partition into aqueous fluids (Audétat, 2010; Candela, 1989; Carten et al., 1993). It is expected that felsic magma with high DI values will be more favorable for large-scale porphyry Mo deposits because a more significant crystal fractionation process would elevate the Mo concentration in the residual melts and the mineralization potential (Li et al., 2014; Shu et al., 2014). Thus, the high-silica, highly oxidized, alkaline- rich, and highly differentiated Caosiyao porphyry should have considerable Mo mineralization potential and its fractionation process may have played an important role in promoting Mo enrichment in the melt and further Mo concentration in the hydrothermal fluids exsolved from the melt. Fluid inclusion studies indicate that multi- Fig. 10. Zircon Hf isotopic compositions of the granite porphyry from the Caosiyao ple episodes of boiling and a decrease in oxygen fugacity of the porphyry Mo deposit. 296 H. Wu et al. / Journal of Asian Earth Sciences 127 (2016) 281–299

Fig. 11. Tectonic evolution of the northern NCC and its adjacent areas during the Late Jurassic (a) and genetic model for the Caosiyao porphyry Mo deposit (b).

ore-forming hydrothermal fluid are the two dominant mechanisms multi-directional and multi-phase faults might have facilitated epi- for mineral deposition (Wang et al., 2014). sodic emplacement of the granitic rocks and provided favorable sites We propose a genetic model for the Caosiyao porphyry Mo for Mo mineralization. Granitic magma, derived from the lower deposit as shown in Fig. 11. During the transition from Indosinian– crust, episodically intruded into the country rocks, and ore- Yanshanian tectonism to far-field tectonics related to the Paleo- forming fluid, exsolved from a highly differentiated granitic magma Pacific subduction (Fig. 11a), fault systems, triggered by regional with high Mo contents, migrated upward along faults, and inter- extension, induced partial melting of the lower crust. The observed acted with the wall rocks and associated fractures, in which the H. Wu et al. / Journal of Asian Earth Sciences 127 (2016) 281–299 297 ore minerals were deposited, resulting in hydrothermal alteration geological significance. Acta Petrol. Sin. 31, 2450–2464 (in Chinese with English and formation of the Caosiyao giant porphyry Mo deposit (Fig. 11b). abstract). Coleman, R.G., 1994. Reconstruction of the Paleo-Asian Ocean. VSP International Science Publishers, Utrecht, The Netherlands, pp. 5–177. 7. Conclusions Davis, G.A., Xu, B., Zheng, Y.D., Zhang, W.J., 2004. Indosinian extension in the Solonker suture zone: the Sonid Zuoqi metamorphic core complex, Inner Mongolia. China Earth Sci. Front. 11, 135–144 (in Chinese with English (1) The hosting granitic intrusion of the Caosiyao giant porphyry abstract). Mo deposit was emplaced at 149–150 Ma, with Mo mineral- Deng, J., Yang, L.Q., Ge, L.S., Wang, Q.F., Zhang, J., Gao, B.F., Zhou, Y.H., Jiang, S.Q., 2006. Research advances in the Mesozoic tectonic regimes during the formation ization occurring at 147–149 Ma. of Jiaodong ore cluster area. Prog. Nat. Sci. 16, 777–784. (2) The granitic rocks are highly differentiated and highly oxi- Deng, J., Yuan, W.M., Carranza, E.J.M., Yang, L.Q., Wang, C.M., Yang, L.Y., Hao, N.N., dized, rich in alkali elements, and show strongly negative 2014. Geochronology and thermochronometry of the Jiapigou gold belt, e northeastern China: new evidence for multiple episodes of mineralization. J. Hf(t) values, indicating origin from partial melting of old Asian Earth Sci. 89, 10–27. lower crust. Deng, J., Wang, C.M., Bagas, L., Carranza, E.J.M., Lu, Y.J., 2015. Cretaceous-Cenozoic (3) The Caosiyao Mo deposit in the northern NCC was formed tectonic history of the Jiaojia Fault and gold mineralization in the Jiaodong Peninsula, China: constraints from zircon U-Pb, illite K-Ar, and apatite fission during regional extension related to the transition from track. Miner. Deposita 50, 987–1006. Indosinian–Yanshanian tectonism to far-field tectonics Du, A.D., He, H.L., Yin, W.N., Zhou, X.Q., Sun, Y.L., Sun, D.Z., Chen, S.Z., Qu, W.J., 1994. caused by the Paleo-Pacific subduction. It is suggested that The study on the analytical methods of Re–Os age for molybdenites. Acta Geol. ancient continental margins are favorable locations for Mo Sinica 68, 339–347 (in Chinese with English abstract). Du, A.D., Wu, S.Q., Sun, D.Z., Wang, S.X., Qu, W.Q., Markey, R., Stain, H., Morgan, J., mineralization. Malinovskiy, D., 2004. Preparation and certification of Re–Os dating reference materials: molybdenites HLP and JDC. Geostand. Geoanal. Res. 28, 41–52. Duan, H.C., Qin, Z.Y., Lin, X.H., Zhang, B.H., Liu, X.W., Zhang, X., Guo, P.Z., Han, F., Qin, L., Dai, J.Z., 2007. Zircon U-Pb ages of intrusive bodies in Dacaoping Acknowledgements molybdenum ore district, Fengning County, Hebei Province. Miner. Deposits 26, 634–642 (in Chinese with English abstract). Fan, W.M., Guo, F., Wang, Y.J., Lin, G., 2003. Late Mesozoic calc-alkaline volcanism of We appreciate the help from and fruitful discussion with engi- post-orogenic extension in the northern Da Hinggan Mountains, northeastern neer X.Z. Li in the Caosiyao Mine during our field investigations. China. J. Volcanol. Geoth. Res. 121, 115–135. We thank C. Li, W.J. Li, and B.Y. Gao for their help with Re–Os dat- Glyuk, D.S., Anfilogov, V.N., 1973. Phase equilibria in the system granite H2O-HF at a 2 ing, and H. Li, H.Y. Wang, and L.H. Wang for their assistance with pressure of 1000 kg/cm . Geochem. Int. 10, 321–325. Goldfarb, R.J., Taylor, R.D., Collins, G.S., Goryachev, N.A., Orlandini, O.F., 2014. major and trace element analyses. We are especially grateful for Phanerozoic continental growth and gold metallogeny of Asia. Gondwana Res. Prof. Qingfei Wang’s helpful suggestions and for language improve- 25, 48–102. ment. Special thanks are also due to Prof. M.F. Zhou and the anony- Griffin, W.L., Pearson, N.J., Belousova, E., Jackson, S.E., Achterbergh, E.V., O’Reilly, S. Y., Shee, S.R., 2000. The Hf isotope composition of cratonic mantle: LAM-MC- mous reviewers for carefully reviewing the manuscript and for ICPMS analysis of zircon megacrysts in kimberlites. Geochim. Cosmochim. Acta their constructive comments and editing suggestions. This 64, 133–148. research was financially supported by the National Natural Science Han, C.M., Xiao, W.J., Zhao, G.C., Sun, M., Qu, W.J., Du, A.D., 2009. A Re-Os study of molybdenite from the Lanjiagou Mo deposit of North China Craton and its Foundation of China (Nos. 41390445 and 41202063), and an open geological significance. Gondwana Res. 16, 264–271. project supported by the Key Laboratory of Mineral Resources, Hou, Z.Q., Zheng, Y.C., Geng, Y.S., 2015. Metallic refertilization of lithosphere along Institute of Geology and Geophysics, Chinese Academy of Sciences. cratonic edges and its control on Au, Mo and REE ore systems. Min. Deposits 34, 641–674 (in Chinese with English abstract). Huang, D.H., Du, A.D., Wu, C.Y., Liu, L.S., Sun, Y.L., Zhou, X.Q., 1996. References Metallochronology of molybdenum (-copper) deposits in the North China Platform: Re-Os age of molybdenite and its geological significance. Min. Deposits 15, 365–373 (in Chinese with English abstract). Audétat, A., 2010. Source and evolution of molybdenum in the porphyry Mo (-Nb) Iizuka, T., Hirata, T., 2005. Improvements of precision and accuracy in in situ Hf deposit at Cave Peak, Texas. J. Petrol. 51, 1739–1760. isotope microanalysis of zircon using the laser ablation-MC-ICPMS technique. Audétat, A., Dolejš, D., Lowenstern, J.B., 2011. Molybdenite saturation in silicic Chem. Geol. 220, 121–137. magmas: occurrence and petrological implications. J. Petrol. 52, 891–904. Ishihara, S., Imai, A., 2014. Oxidized granitic magmas and porphyry copper Black, L.P., Gulson, B.L., 1978. The age of the Mud Tank carbonatite, Strangways mineralization. In: Kumar, S., Singh, R.N. (Eds.), Modelling of Magmatic and Range, Northern Territory. BMR J. Aust. Geol. Geophys. 3, 227–232. Allied Processes. Society of Earth Scientists Series. Springer International Blichert-Toft, J., Albarède, F., 1997. The Lu–Hf isotope geochemistry of chondrites Publishing, Switzerland, pp. 209–223. and the evolution of the mantle-crust system. Earth Planet. Sci. Lett. 148, 243– Isuk, E.E., Carman, J.H., 1981. The system Na Si 0 –K Si 0 –MoS –H 0 with 258. 2 2 5 2 2 5 2 2 implications for molybdenum transport in silicate melts. Econ. Geol. 76, Boynton, W.V., 1984. Geochemistry of the rare earth elements: meteorite studies. 2222–2235. In: Henderson (Ed.), Rare Earth Element Geochemistry. Elsevier, pp. 63–114. Jin, X.D., Li, W.J., Xiang, P., Sakyi, P.A., Zhu, M.T., Zhang, L.C., 2013. A contribution to Bureau of Geology and Mineral Resources of Inner Mongolia (BGMRIM), 1991. common Carius tube distillation techniques. J. Anal. At. Spectrom. 28, 396–404. Regional Geology of Nei Mongol (Inner Mongolia) Autonomous Region. Leng, C.B., Zhang, X.C., Huang, Z.L., Huang, Q.Y., Wang, S.X., Ma, D.Y., Luo, T.Y., Li, C., Geological Publishing House, Beijing, p. 775 (in Chinese with English abstract). Li, W.B., 2015. Geology, Re-Os ages, sulfur and lead isotopes of the Diyanqinamu Candela, P.A., Holland, H.D., 1986. A mass transfer model for copper and porphyry Mo deposit, Inner Mongolia, NE China. Econ. Geol. 110, 557–574. molybdenum in magmatic hydrothermal systems; the origin of porphyry- Li, J.Y., 2006. Permian geodynamic setting of Northeast China and adjacent regions: type ore deposits. Econ. Geol. 81, 1–19. closure of the Paleo-Asian Ocean and subduction of the Paleo-Pacific Plate. J. Candela, P.A., 1989. Felsic magmas, volatiles, and metallogenesis. Rev. Econ. Geol. 4, Asian Earth Sci. 26, 207–224. 223–233. Li, N., Chen, Y.J., Zhang, H., Zhao, T.P., Deng, X.H., Wang, Y., Ni, P.Y., 2007. Cao, H.W., Zhang, S.T., Santosh, M., Zheng, L., Tang, L., Li, D., Zhang, X.H., Zhang, Y.H., Molybdenum deposits in East Qinling. Earth Sci. Front. 14, 186–198 (in Chinese 2015. The luanchuan Mo–W–Pb–Zn–Ag magmatic-hydrothermal system in the with English abstract). East Qinling metallogenic belt, China: Constrains on metallogenesis from C–H– Li, Y.F., Mao, J.W., Hu, H.B., Guo, B.J., Bai, F.J., 2005. Geology, distribution, types and O–S–Pb isotope compositions and Rb-Sr isochron ages. J. Asian Earth Sci. 111, tectonic settings of Mesozoic molybdenum deposits in East Qinling area. Min. 751–780. Deposits 24, 292–304 (in Chinese with English abstract). Carten, R., White, W., Stein, H., 1993. High-grade granite-related molybdenum Li, Z.Z., Qin, K.Z., Li, G.M., Ishihara, S., Jin, l.Y., Song, G.X., Meng, Z.J., 2014. Formation systems: classification and origin. Mineral Deposit Modeling: Geological of the giant Chalukou porphyry Mo deposit in northern Great Xing’an Range, NE Association of Canada Special Paper, 40, pp. 521–554. China: partial melting of the juvenite lower crust in untra-plate extensional Chen, Y.J., Zhai, M.G., Jiang, S.Y., 2009. Significant achievements and open issues in environment. Lithos 202–203, 138–1156. study of orogenesis and metallogenesis surrounding the North China Craton. Li, X.Z., Ban, Y.L., Quan, Z.X., Weng, J.C., Wang, W.D., 2012. Discuss on the Acta Petrol. Sin. 25, 2695–2726 (in Chinese with English abstract). Molybdenum deposit geochemical characteristics and metallogenic model in Chen, Y.J., Zhang, C., li, N., Yang, Y.F., Deng, K., 2012. Geology of the Mo deposits in Xinghe County, Inner Mongolia. Geol. Surv. Res. 35, 39–146 (in Chinese with Northeast China. J. Jilin Univ. 42, 1223–1268 (in Chinese with English abstract). English abstract). Cheng, G.H., Wang, R.L., Zeng, Q.D., Guo, Y.P., Duan, X.X., Wei, J.J., Zhang, J.S., Gao, X. Li, Y.F., Mao, J.W., Liu, D.Y., Wang, Y.B., Wang, Z.L., Wang, Y.T., Li, X.F., Zhang, Z.H., H., 2015. Zircon U–Pb ages, Hf isotopes of the granitoids and Re-Os ages of the Guo, B.J., 2006. Shrimp zircon U–Pb and molybdenite Re–Os datings for the molybdenite in Luming molybdenum ore area, Heilongjiang province, and its 298 H. Wu et al. / Journal of Asian Earth Sciences 127 (2016) 281–299

Leimengou porphyry molybdenum deposit, western Henan and its geological Shu, Q., Lai, Y., Zhou, Y., Xu, J., Wu, H., 2015. Zircon U-Pb geochronology and Sr-Nd- implication. Geol. Rev. 52, 122–131 (in Chinese with English abstract). Pb-Hf isotopic constraints on the timing and origin of Mesozoic granitoids Liu, Y.S., Hu, Z.C., Gao, S., Günther, D., Xu, J., Gao, C.G., Chen, H.H., 2008. In situ hosting the Mo deposits in northern Xilamulun district, NE China. Lithos 238, analysis of major and trace elements of anhydrous minerals by LA-ICP-MS 64–75. without applying an internal standard. Chem. Geol. 257 (1–2), 34–43. Smoliar, M.I., Walker, R.J., Morgan, J.W., 1996. Re–Os ages of group IIA, IIIA, IVA, and Ludwig, K.R., 2001. Users manual for Isoplot/Ex (rev. 2.49): A geochronological IVB iron meteorites. Science 271, 1099. toolkit for Microsoft Excel. Berkeley Geochronology Center Special Publication Soderlund, U., Patchett, P.J., Vervoort, J.D., Isachsen, C.E., 2004. The 176Lu decay 1, pp. 1–55. constant determined by Lu–Hf and U-Pb isotope systematics of Precambrian Ludwig, K.R., 2003. User’s Manual for Isoplot/Ex, Version 3.00, A Geochronological mafic intrusions. Earth Planet. Sci. Lett. 219, 311–324. Toolkit for Microsoft Excel. Berkeley Geochronology Center Special Publication, Stein, H.J., Markey, R.J., Morgan, J.W., Du, A.D., Sun, Y., 1997. High precise and Berkeley, USA. accurate Re–Os ages for molybdenite from the east Qinling molybdenum belt, Luo, M.J., Zhang, F.M., Dong, Q.Y., Xu, Y.R., Li, S.M., Li, H.H., 1991. Mo Deposits in Shanxi province, China. Econ. Geol. 92, 827–835. China. Henan Press of Science and Technology, Zhengzhou, p. 408 (in Chinese). Stein, H.J., Markey, R.J., Morgan, J.W., Hannah, J.L., Schersten, A., 2001. The Mao, J.W., Hua, R.M., Li, X.B., 1999. A Preliminary study of large-scale metallogenic remarkable Re–Os chronometer in molybdenite: how and why it works. Terra and large clusters of mineral deposits. Min. Deposits 18, 291–299 (in Chinese Nova 13, 479–486. with English abstract). Štemprok, M., 1975. Geological significance of immiscibility in fused silicate Mao, J.W., Zhang, Z.H., Yu, J.J., Wang, Y.T., Niu, B.G., 2003. Geodynamic settings of systems containing tungsten and molybdenum. Int. Geol. Rev. 17, 1306–1316. Mesozoic large-scale mineralization in the North China and adjacent areas: Sun, S.S., McDonough, W.F., 1989. Chemical and isotopic systematic of oceanic implication from the highly precise and accurate ages of metal deposits. Sci. basalts: implication for mantle composition and processes. In: Saunders, A.D., China Ser. D Earth 33, 289–1299 (in Chinese). Norry, M.J. (Eds), Magmatism in Oceanic Basins. Geological Society, London, Mao, J.W., Xie, G.Q., Zhang, Z.H., Li, X.F., Wang, Y.T., Zhang, C.Q., Li, Y.F., 2005. Special Publications 42, pp. 313–345. Mesozoic large-scale metallogenic pulses in North China and corresponding Wallace, S.R., MacKenzie, W.B., Blair, R.G., Muncaster, N.K., 1978. Geology of the geodynamic settings. Acta Petrol. Sin. 21, 169–188 (in Chinese with English Urad and Henderson molybdenite deposits, Clear Creek County, Colorado, with abstract). a section on a comparison of these deposits with those at Climax, Colorado. Mao, J.W., Pirajno, F., Xiang, J., Gao, J., Ye, H., Li, Y., Guo, B., 2011. Mesozoic Econ. Geol. 73, 325–368. molybdenum deposits in the east Qinling-Dabie orogenic belt: characteristics Wan, B., Hegner, E., Zhang, L.C., Rocholl, A., Chen, Z.G., Wu, H.Y., Chen, F.K., 2009. Rb- and tectonic settings. Ore Geol. Rev. 43, 264–1293. Sr geochronology of chalcopyrite from the Chehugou porphyry Mo-Cu deposit Meng, Q.R., 2003. What drove late Mesozoic extension of the northern China- (Northeast China) and geochemical constraints on the origin of hosting granites. Mongolia tract? Tectonophysics 369, 155–174. Econ. Geol. 104, 351–363. Meng, Z.J., Kan, X.S., Li, X.C., Wang, J.P., Zhang, R.Z., Lu, K.P., Sun, Z.J., Shi, Y.J., Zhang, Wang, G.R., Wu, G., Wu, H., Liu, J., Li, X.Z., Xu, L.Q., Zhang, T., Quan, Z.X., 2014. Fluid J.N., Wang, H.Y., 2011. The discovery and exploration process of the Chalukou inclusion and hydrogen-oxygen isotope study of Caosiyao superlarge porphyry giant porphyry molybdenum polymetallic deposit in forest-covered area of molybdenum deposit in Xinghe County, central Inner Mongolia. Min. Deposits northeastern Da Hinggnan Mountains and its geological significance. Geol. 33, 1213–1232 (in Chinese with English abstract). China 38, 1504–1517 (in Chinese with English abstract). Wei, R., Wang, J.G., Wang, Y.T., Wang, S.W., 2013. Zircon U-Pb dating of adamellite Nie, F.J., Liu, Y.F., Zhao, Y.A., Cao, Y., 2012. Discovery of Dasuji and Caosiyao large- from the Sadaigoumen porphyry molybdenum deposit in Fengning, Hebei size Mo deposits in Central Inner Mongolia and its geological significances. Min. Province, and its significance. Geol. China 40, 1736–1748 (in Chinese with Deposits 31, 930–1940 (in Chinese with English abstract). English abstract). Nie, F.J., Li, X.Z., Li, C., Zhao, Y.A., Liu, Y.F., 2013. Re-Os isotopic age dating of the White, W., Bookstrom, A., Kamilli, R., Ganster, M., Smith, R., Ranta, D., Steininger, R., Molybdenite separated from the Caosiyao giant molybdenum deposit, Xinghe 1981. Character and origin of Climax-type molybdenum deposits. Econ. Geol. County, Inner Mongolia, and its geological significances. Geol. Rev. 59, 175– 75, 270–316. 1181 (in Chinese with English abstract). Wiedenbeck, M. et al., 1995. Three natural zircon standards for U-Th-Pb, Lu-Hf, No. 2 Geoexploration Institute of Henan Bureau of Geoexploration and Mineral trace-element and Ree analyses. Geostand. Newslett. 19, 1–23. Development (NGIHBGMD), 2013. Report of the Caosiyao Mo deposit in Xinghe Wiedenbeck, M. et al., 2004. Further characterisation of the 91500 zircon crystal. County, Inner Mongolia, pp 1–159 (in Chinese). Geostand. Geoanal. Res. 28, 9–39. Pei, R.F., Lu, F.X., Fan, J.Z., 1998. Metallogenic Series and Prospecting of the Metal Windley, B.F., Kröner, A., Guo, J.H., Qu, G.S., Li, Y.Y., Zhang, C., 2002. Neoproterozoic Deposits in North Margin of the North China Craton. Geological Publishing to Paleozoic Geology of the Altai Orogen, NW China: new zircon age data and House, Beijing, p. 237 (in Chinese). tectonic evolution. J. Geol. 110, 719–737. Pirajno, F., Ernst, R.E., Borisenko, A.S., Fedoseev, G., Naumov, E.A., 2009. Intraplate Woodhead, J., Hergt, J., Shelley, M., Eggins, S., Kemp, R., 2004. Zircon Hf-isotope magmatism in Central Asia and China and associated metallogeny. Ore Geol. analysis with an excimer laser, depth profiling, ablation of complex geometries, Rev. 35, 114–136. and concomitant age estimation. Chem. Geol. 209, 121–135. Pirajno, F., 2013. The Geology and Tectonic Settings of China’s Mineral Deposits. Wu, H.Y., Zhang, L.C., Wan, B., Chen, Z.G., Zhang, X.J., Xiang, P., 2011. Springer, Berlin, pp. 35–108. Geochronological and geochemical constraints on Aolunhua porphyry Mo–Cu Pirajno, F., Zhou, T.F., 2015. Intracontinental porphyry and porphyry-skarn mineral deposit, northeast China, and its tectonic significance. Ore Geol. Rev. 43, 78–91. systems in Eastern China: scrutiny of a special case ‘‘made in China”. Econ. Geol. Wu, H.Y., Zhang, L.C., Pirajno, F., Xiang, P., Wan, B., Chen, Z.G., Zhang, X.J., 2014. The 110, 603–629. Jiguanshan porphyry Mo deposit in the Xilamulun metallogenic belt, northern Qin, F., Liu, J.M., Zeng, Q.D., Zhang, R.B., 2008. The metallogenic epoch and source of margin of the North China Craton, U–Pb geochronology, isotope systematics, ore-forming materials of the Xiaodonggou porphyry molybdenum deposit, geochemistry and fluid inclusion studies: Implications for a genetic model. Ore Inner Mongolia. Geoscience 22, 173–180 (in Chinese with English abstract). Geol. Rev. 56, 549–565. Santosh, M., 2010. Assembling North China Craton within the Columbia Wu, F.Y., Yang, Y.H., Xie, L.W., Yang, J.H., Xu, P., 2006. Hf isotopic compositions of the supercontinent: the role of double-sided subduction. Precambr. Res. 178, 149–167. standard zircons and baddeleyites used in U–Pb geochronology. Chem. Geol. Santosh, M., Zhao, D.P., Kusky, T.M., 2010. Mantle dynamics of the Paleoproterozoic 234, 105–126. North China Craton: a perspective based on seismic tomography. J. Geodyn. 49, Xiao, W.J., Windley, B.F., Hao, J., Zhai, M.G., 2003. Accretion leading to collision and 39–53. the Permian Solonker suture, Inner Mongolia, China: termination of the central Seedorff, E., Einaudi, M.T., 2004a. Henderson Porphyry Molybdenum System, Asian orogenic belt. Tectonics 22, 1069–1088. Colorado: I. Sequence and abundance of hydrothermal mineral assemblages, Xie, X.J., Yan, M.C., Li, L.Z., Shen, H.J., 1985. Usable values for chinese standard flow paths of evolving fluids, and evolutionary style. Econ. Geol. 99, 3–37. reference samples of stream sediments, soils, and rocks: GSD 9–12, GSS 1–8 and Seedorff, E., Einaudi, M.T., 2004b. Henderson Porphyry Molybdenum System, GSR 1–6. Geostand. Newslett. 9, 277–280. Colorado: II. Decoupling of introduction and deposition of metals during Xie, L.W., Zhang, Y.B., Zhang, H.H., Sun, J.F., Wu, F.Y., 2008. In situ simultaneous geochemical evolution of hydrothermal fluids. Econ. Geol. 99, 39–72. determination of trace elements, U–Pb and Lu–Hf isotopes in zircon and Selby, D., Creaser, R.A., 2001. Re–Os geochronology and systematics in molybdenite baddeleyite. Chin. Sci. Bull. 53, 1565–1573. from the Endako porphyry molybdenum deposit, British Columbia, Canada. Xue, H.T., Quan, Z.X., Li, D.Z., Zhang, B., Ding, B., Fu, Z.G., 2015. Characteristics of ore- Econ. Geol. 96, 197–204. forming hydrothermal alteration and mineral association in Caosiyao super- Selby, D., Creaser, R.A., 2004. Macroscale NTIMS and microscale LA-MC-ICP-MS Re- large Mo deposit in Xinghe of Inner Mongolia. Min. Resour. Geol. 29, 411–419 Os analysis of molybdenite: Testing spatial restrictions for reliable Re-Os age (in Chinese with English abstract). determinations, and implications for the decoupling of Re and Os within Yang, J.H., Wu, F.Y., Shao, J.A., Wilde, S.A., Xie, L.W., Liu, X.M., 2006. Constraints on molybdenite. Geochim. Cosmochim. Acta 68, 3897–3908. the timing of uplift of the Yanshan Fold and Thrust Belt, North China. Earth Sengör, A.M.C., Natal’in, B.A., 1996. Paleotectonics of Asia: Fragments of a Synthesis. Planet. Sci. Lett. 246, 336–352. The Tectonic Evolution of Asia. Cambridge University Press, Cambridge, pp. Yang, L., 2013. Geochemistry and Metallogenic Geodynamic Setting of the Late 486–640. Mesozoic Molybdenite Deposits in the Eastern Qinling Orogen, Central China. Shen, C.L., Zhang, M., Yu, X.Q., Chen, W.G., Gao, W.Y., Zhou, W.C., 2010. New Doctoral Dissertation, pp 1–122 (in Chinese with English abstract). progresses in exploration of molybdenum deposits and analysis of Ye, H.S., Mao, J.W., Li, Y.F., Guo, B.J., Zhang, C.Q., Liu, J., Yan, Q.R., Liu, G.Y., 2006. mineralization prospect in Inner Mongolia. Geol. Explor. 46, 561–575 (in Shrimp zircon U–Pb and molybdenite Re–Os dating for the superlarge Donggou Chinese with English abstract). porphyry Mo deposit in east Qinling, China, and its geological implication. Acta Shu, Q., Lai, Y., Wang, C., Xu, J., Sun, Y., 2014. Geochronology, geochemistry and Sr- Geolog. Sin. 80, 1078–1088 (in Chinese with English abstract). Nd-Hf isotopes of the Haisugou porphyry Mo deposit, northeast China, and their York, D., 1969. Least squares fitting of a straight line with correlated errors. Earth geological significance. J. Asian Earth Sci. 79, 777–791. Planet. Sci. Lett. 5, 320–324. H. Wu et al. / Journal of Asian Earth Sciences 127 (2016) 281–299 299

Zeh, A., Gerdes, A., Klemd, R., Barton, J.M., 2007. Archaean to Proterozoic crustal Zhang, T., Chen, Z.Y., Xu, L.Q., Chen, Z.H., 2009. The Re–Os isotopic dating of evolution in the Central zone of the Limpopo belt (South Africa-Botswana): molybdenite from the Dasuji molybdenum deposit in Zhuozi county of Inner constraints from combined U-Pb and Lu-Hf isotope analyses of zircon. J. Petrol. Mongolia and its geological signiﬁcance. Rock Min. Anal. 28, 279–282 (in 24, 1605–1639. Chinese with English abstract). Zeng, Q.D., Liu, J.M., Zhang, Z.L., Chen, W.J., Zhang, W.Q., 2011. Geology and Zhang, L.C., Wu, H.Y., Xiang, P., Zhang, X.J., Chen, Z.G., Wan, B., 2010. Ore-forming geochronology of the Xilamulun molybdenum metallogenic belt in eastern processes and mineralization of complex tectonic system during the Mesozoic: Inner Mongolia, China. Int. J. Earth Sci. 100, 1791–1809. a case for Xilamulun Cu–Mo metallogenic belt. Acta Petrol. Sin. 26, 1351–1362 Zeng, Q.D., Liu, J.M., Yu, C.M., Ye, J., Liu, H.T., 2012. Metal deposits in the Da Hinggan (in Chinese with English abstract). Mountains, NE China: styles, characteristics, and exploration potential. Int. Zhang, X.J., Zhang, L.C., Jin, X.D., Wu, H.Y., Xiang, P., Chen, Z.G., 2010. U-Pb ages, Geol. Rev. 53, 846–878. geochemical characteristics and their implications of Banlashan Molybdenum Zhai, M.G., Yang, J.H., Liu, W.J., 2001. Large clusters of gold deposits and large-scale Deposit. Acta Petrol. Sin. 26, 1411–1422 (in Chinese with English abstract). metallogenesis in the Jiaodong peninsula, eastern China. Sci. China Ser. D 44, Zhao, G.C., Wilde, S.A., Cawood, P.A., Sun, M., 2001. Archean blocks and their 758–768. boundaries in the North China Craton: lithological, geochemical, structural and Zhai, M.G., Zhu, R.X., Liu, J.M., Meng, Q.R., Hou, Q.L., Hu, S.B., Li, Z., Zhang, H.F., Liu, P-T path constraints and tectonic evolution. Precambr. Res. 107, 45–73. W., 2003. Time-range of Mesozoic tectonic regime inversion in eastern north Zhou, L.L., Zeng, Q.D., Liu, J.M., Friis, H., Zhang, Z.L., Duan, X.X., Lan, T.G., 2014. China block. Sci. China (Ser. D) 33, 913–920 (in Chinese). Geochronology of magmatism and mineralization of the Daheishan giant Zhai, M.G., Meng, Q.R., Liu, J.M., Hou, Q.L., Hu, S.B., Li, Z., Zhang, H.F., Liu, W., Shao, J. porphyry molybdenum deposit, Jilin Province, Northeast China: constraints A., Zhu, R.X., 2004. Geological features of Mesozoic tectonic regime inversion in on ore genesis and implications for geodynamic setting. Int. Geol. Rev. 56, Eastern North China and implication for geodynamics. Earth Sci. Front. 11, 285– 1–25. 298 (in Chinese with English abstract). Zhou, X.H., Sun, M., Zhang, G.H., Chen, S.H., 2002. Continental crust and lithospheric Zhao, H.J., Mao, J.W., Ye, H.S., Hou, K.J., Liang, H.S., 2010. Chronology and mantle interaction beneath North China: isotopic evidence from granulite petrogenesis of Shijiawan granite porphyry in Shanxi province: constrains xenoliths in Hannuoba, Sino-Korean craton. Lithos 62, 111–124. from zircon U–Pb geochronology and Hf isotopic compositions. Min. Deposits Zhu, L.M., Zhang, G.W., Guo, B., Li, B., 2008. U-Pb (LA-ICP-MS) Zircon dating for the 29, 143–157 (in Chinese with English abstract). large Jinduicheng porphyry Mo deposit in the east Qinling, China, and its Zhao, Y., Chen, B., Zhang, S.H., Liu, J.M., Hu, J.M., Liu, J., Pei, J.L., 2010. Pre-Yanshanian metallogenic geodynamical setting. Acta Geol. Sin. 82, 204–220 (in Chinese geological events in the northern margin of the North China craton and its with English abstract). adjacent areas. Geol. China 37, 900–915 (in Chinese with English abstract). Zhu, R.X., Chen, L., Wu, F.Y., Liu, J.L., 2011. Timing, scale and mechanism of the Zhang, L.C., Wu, H.Y., Wan, B., Chen, Z.G., 2009. Ages and geodynamic settings of destruction of the North China Craton. Sci. China Earth Sci. 41, 789–797. Xilamulun Mo–Cu metallogenic belt in north of North China Craton. Gondwana Zhu, R.X., Xu, Y.G., Zhu, G., Zhang, H.F., Xia, Q.K., Zheng, T.Y., 2012. Destruction of the Res. 16, 243–254. North China Craton. Sci. China Earth Sci. 42, 1135–1159.