The Triassic Bilugangan deposit: Geological constrains on the genesis of one of the oldest Mo deposits in Inner Mongolia, China

Ore Geology Reviews 107 (2019) 837–852

Contents lists available at ScienceDirect

Ore Geology Reviews journal homepage: www.elsevier.com/locate/oregeorev

The Triassic Bilugangan deposit: Geological constrains on the genesis of one of the oldest Mo deposits in Inner Mongolia, China

T

⁎

Lili Zhanga,b, Sihong Jianga, , Leon Bagasa,c, Yifei Liua a

MNR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, CAGS, Beijing 100037, China Key Laboratory of Orogen and Crust Evolution, Peking University, Beijing 100871, China c Centre for Exploration Targeting, The University of Western Australia, Crawley, WA 6009, Australia b

A R T I C LE I N FO

A B S T R A C T

Keywords: Molybdenite Re-Os age S-Pb-H-O isotopes Porphyry Mo deposit Bilugangan Eastern Central Asian Orogen

The large Bilugangan porphyry Mo deposit is one of the oldest Mo deposit in eastern part of the Central Asian Orogen in Inner Mongolia. The orogen is currently regarded as the most important Phanerozoic region with widespread crustal growth between the Siberian Craton to the north, and North China Block to the south. The Bilugangan Mo mineralisation is hosted by a porphyritic monzogranite and along the contact with the Late Permian Linxi Formation. The mineralisation is disseminated in places and includes various types of hydrothermal veins. The mineralising stages of the deposit includes the pre-ore quartz–K-feldspar(–biotite) pegmatite succeeded by quartz–K-feldspar–molybdenite–muscovite–sericite(–pyrite) veins, quartz–molybdenite–chalcopyrite–perthite–muscovite–sericite(–pyrite–sphalerite), and post-ore quartz–fluorite–calcite (–sericite–muscovite–) veins. Seven molybdenite samples from the mineralisation yield a Re-Os Mo weighted mean date of 238 ± 1 Ma, which is the same, within error, as the Re-Os isochron age of 238 ± 2 Ma, and the ca. 240 Ma age of the porphyritic monzogranite. This is the oldest porphyry Mo – type deposit in the eastern part of the orogen, and the only large –sized Mo deposit in the region, which shows that the east CAO is prospective for Triassic mineralisation. Thirty-three samples of sulfide from the deposit have a narrow δ34SVCDT(‰) range of 1.5 to 4.3‰, indicating that the sulfur the sulfur has primarily a magmatic source. The sulfides from the Mo-bearing veins have relatively concentrated Pb isotopic compositions with 206Pb/204Pb ratios between 18.295 and 19.576, 207 Pb/204Pb ratios between 15.535 and 15.662, and 208Pb/204Pb ratios between 38.066 and 38.653. These values are consistent with those of the initial Pb isotope ratios for whole rock samples from the porphyritic monzogranite and hornfels. Fifteen gangue quartz samples from various veins define a range of δ18Ofluid values from 0.5 to 5.2‰ with δDfluid values ranging from −115 to −60‰, indicating that the onset of the mineralising fluid was generated from in-situ degassing of a magmatic source, followed by an input of meteoric water during the late ore-forming stage. It is proposed that the deposit is a collision-related Dabie-type deposit, which is related to the closure of the Paleo-Asian Ocean between the North China Block and Siberian Craton.

1. Introduction Molybdenum disulfide (MoS2) is the principal sulfide in large lowgrade porphyry Mo (–Cu) and Cu (–Mo) deposits (USGS, 2016). Porphyry Mo deposits are commonly present in within-plate, subductionrelated continental arc, and rift-related tectonic settings (e.g. Sillitoe, 1980; Chen et al., 2017a). China produced over 202,000 t of Mo in 2015, and has a Mo resource of 8.6 Mt, which accounts for approximately 38% of the Mo produced in the world and around 40% of the world’s Mo resources (USGS, 2016). Large syn- to post-collisional Mo deposits are present in the Central Asian Orogen (CAO) to the north of the North China Block

⁎

(NCB) and the Qingling-Dabie Orogen along the southern margin of NCB (Chen et al., 2009, 2012, 2017b). The Qingling-Dabie Orogen is characterised by high-pressure deformation associated with the collision of the NCB and South China continents (Zheng et al., 2012; Wu and Zheng, 2013). The CAO has been multiply deformed during subduction and collisional events associated with the Paleozoic to early Mesozoic evolution of the PaleoAsian Ocean. Deformation in CAO is commonly interpreted as being associated with long-term accretionary orogenies accompanied by the growth of voluminous juvenile complexes during Paleozoic to early Triassic. This was followed by the closure of the Mongol-Okhotsk Ocean in the northeast and westwards subduction of the Paleo-Pacific Ocean

Corresponding author at: Institute of Mineral Resources, Chinese Academy of Geological Sciences, No. 26 Baiwanzhuang Rd., Beijing 100037, China. E-mail address: [email protected] (S. Jiang).

https://doi.org/10.1016/j.oregeorev.2019.03.025 Received 23 April 2018; Received in revised form 25 December 2018; Accepted 22 March 2019 Available online 26 March 2019 0169-1368/ © 2019 Elsevier B.V. All rights reserved.

Ore Geology Reviews 107 (2019) 837–852

L. Zhang, et al.

Fig. 1. Simplified geological map of the Great Hingan Range and surrounding areas showing the distribution of Triassic Mo deposits (modified after Xu et al., 2015; Chen et al., 2017b).

favourable for Mo mineralisation. Moreover, there was no significant Mo deposit formed during or before the Triassic known until now, and this area has thus been considered not to be prospective for Mo deposits older than Jurassic. The discovery of the large Bilugangan Mo-dominated deposit may give us a further understanding of the genesis of Mo deposits, and also shows that the eastern part of the orogen is prospective for Triassic or older Mo mineralisation. The Bilugangan deposit contains a resource of 410,000 t averaging 0.085% Mo, and 16,000 t Cu averaging 0.43% Cu (Tang et al., 2012; Li et al., 2016a,b). Studies on the deposit have included geochronology and fluid inclusion measurements, which have been quickly completed without any integrated analysis of its geology and genesis (Tang et al., 2012, Liu et al., 2012a; Li et al., 2016a,b). This contribution presents detailed geological information on the region around the Bilugangan porphyry Mo deposit and documents new Re-Os dates and H-O and S-Pb isotopic data for the deposit that help define the timing and source of Mo-bearing fluids and ore-forming materials, and constrain the ore genesis.

in the east (Sengör and Natal’in, 1996; Li, 2006; Xiao et al., 2009, 2015; Han et al., 2012; Zhou and Wilde, 2013; Xu et al., 2015; Yakubchuk, 2017). Numerous Triassic to Cretaceous Mo deposits are located in eastern CAO and along the north margin of NCB. There are two Mo–mineralising events in the orogen dated at ca. 250–200 Ma in the Triassic, and ca. 180–130 Ma during the Jurassic to Cretaceous (Fig. 1; Zeng et al., 2012; Chen et al., 2017b). The Triassic deposits form a linear zone along the northern margin of NCB, and are interpreted to be associated with syn- to post-collisional deformation (Zeng et al., 2012; Chen et al., 2017b). Most of the Mo deposits in eastern CAO are Jurassic to early Cretaceous in age, and interpreted as being deposited in a continentalarc settings located in a subduction zone or a back-arc basin during the evolution of Mongol-Okhotsk Ocean, or westward subduction of PaleoPacific plate (Zeng et al., 2012; Chen et al., 2017b). Although these deposits have various tectonic settings, Chen et al. (2017b) propose that the Mo mineralisation was deposited in a mature continental crust along the northern part of NCB and southern NCB and the Qinling Orogen. The Bilugangan deposit is different having formed during the Triassic and located near the Hegenshan-Heihe Fault in eastern CAO (Fig. 1). The region around the fault is characterised by the presence of immense volumes of juvenile crust formed during the Paleozoic-Triassic rather than a mature continent crust that were considered to be

2. Geological setting The easternmost part of CAO is located south of the MongolOkhotsk Fault, and north of the Kangbao-Chifeng Fault (Fig. 1). The area includes fault bound terranes known as the Erguna Terrane in the north, Hingan Terrane, Songliao Terrane that includes the Planerozoic 838

Ore Geology Reviews 107 (2019) 837–852

L. Zhang, et al.

Fig. 2. Simplified geological map of the Bilugangan Mo deposit showing the location of sampled diamond-drillholes (modified after No. 6 GT, 2012).

2011). The Mesozoic granitic rocks and consists of ca. 247 to 111 Ma granodiorite, monzogranite, and syenogranite, interpreted as having a juvenile lower crustal source (Jahn et al., 2000; Liu et al., 2005; Wu et al., 2011). Molybdenite-bearing mineral deposits around Bilugangan were deposited during the Paleozoic to Cretaceous. A small proportion of Paleozoic deposits containing subordinate Mo are also known in the area, such as the Bainaimiao Cu–Au–Mo, Zhunsujihua, Haolibao and Duobaoshan Cu(– Mo) deposits. These are interpreted as porphyry deposits related to subduction of the Paleo-Asian Oceanic plate (Xiang et al., 2012; Liu et al., 2012a,b,c; Zeng et al., 2013; Feng et al., 2015; Chen et al., 2017b). Almost all the Mo deposits are Jurassic to early Cretaceous (ca. 180–130 Ma) in age. Early to Middle Jurassic Mo deposits are located in the Lesser Hingan and Zhangguangcai ranges and have a post-collisional tectonic setting following the closure of the Paleo-Asian Ocean, and the Late Jurassic to Early Cretaceous deposits cluster in the Great Hingan Range and are related to the Mesozoic continental-arc settings in the Mongol-Okhotsk Ocean (Chen et al., 2017b). Only the small- to medium-sized Triassic Gaogangshan and Laojiagou Mo deposits were known to be presented in eastern CAO before Bilugangan was

Songliao Basin, and Jiamusi Terranes in the south in contact with NCB. The terranes are interpreted as continental crustal fragments (Fig. 1; Ren et al., 1990; Sengör et al., 1993; Xu et al., 1994; Nie et al., 1994; Li, 2006; Xiao et al., 2009; Xu et al., 2015). The Xilinhot Complex, located in the western part of the Songliao Terrane, contains Precambrian, Ordovician to Permian and Jurassic to Tertiary supracrustal rocks, and Paleozoic to Mesozoic intrusive rocks (Fig. 1; Nie et al., 2016). Precambrian plagioclase amphibolite and actinolite schist have imprecise Sm-Nd isochron dates of 1910 ± 72, 1394 ± 46 and 1025 ± 41 Ma (Xu et al., 1994, 1996; Nie et al., 1994). The Ordovician to Permian units are sparse, low-grade metamorphic volcanic and deep-water sedimentary rocks consisting of andesite, schist, sandy slate, and marble. The units are unconformably overlaid by widespread continental Jurassic to Tertiary intermediate- to felsic volcanic rocks interbedded with minor sedimentary beds (Liu et al., 2004). The Permian and older rocks are unconformably overlain by Jurassic rocks that host 90% of the mineral deposits in the study region (Liu et al., 2004). The intrusive rocks around Bilugangan are predominantly Mesozoic and lesser Paleozoic units. The Paleozoic plutonic rocks include diorite, tonalite, and granodiorite dated between ca. 499 and 252 Ma (Wu et al., 839

Ore Geology Reviews 107 (2019) 837–852

L. Zhang, et al.

Fig. 3. Photographs and photomicrographs showing host rocks and mineralisation: (a) porphyritic monzogranite from Ore Section C (831 m at ZK063); (b) an xenolith of hornfels in the porphyritic monzogranite from the open pit in Ore Section A; (c) hornfels of the Late Permian Linxi Formation from Ore Section C (309 m at ZK 463); (d) porphyritic monzogranite of Fig. 4a with K-feldspar, plagioclase, quartz as the main phenocrysts. Sericite and muscovite alteration are present in the matrix; (e) Sample BL16-26 of molybdenite-chalcopyrite-pyrite in porphyritic monzogranite from Ore Section A; and (f) micro crystalloblastic texture and minerals of the hornfels in Fig. 4c. Abbreviations: Qtz, quartz; Kfs, K-feldspar; Bt, biotite; Mo, molybdenite; Py, pyrite; Ccp, chalcopyrite; Ms, muscovite.

Fig. 4. Sketch of geological profiles at the Bilugangan Mo deposit: (a) No. 52 at Ore Section A, (b) No. 5 at Ore Section B, and (c) No. 63 at Ore Section C. The sketch shows the outline of mineralised zones and the location of samples from the study area (modified after No. 6 GT, 2012). The locations of the profiles are shown in Fig. 3.

840

Ore Geology Reviews 107 (2019) 837–852

L. Zhang, et al.

Proportion of total Mo/ Cu resource (%)

discovered. This was at a time when the region was thought to have low prospectivity for large Triassic Mo mineralisation (Zhang et al., 2014; Duan et al., 2015).

35.69 3.12 0.36 1.11 4.13

3.1. Host rocks

2300 1000 450 700 500

1100 700 450 650 850

3.66 ∼ 151.97 3.86 ∼ 52.35 1.80 ∼ 8.75 1.80 ∼ 7.52 1.79 ∼ 85.00

145,783 12,743 1474 4542 16,852

0.082 0.089 0.081 0.077 0.082

The Bilugangan Mo deposit is in the Xilinhot Complex south of the Hegenshan-Heihe Fault (Fig. 1). The host rocks are porphyritic monzogranite and the hornfelsed Linxi Formation. The porphyritic monzogranite forms small discontinuous outcrops in a NE-trending and SE plunging area covering ∼1.3 km2, and commonly contains xenoliths, particularly in the contact zone with the Linxi Formation (Figs. 2 and 3a–c; No. 6 GT, 2012). The monzogranite has a porphyritic-like texture and contains phenocrysts are K-feldspar (10–15 vol%), quartz (5–10 vol %), plagioclase (5–10 vol%), and minor amounts of biotite and muscovite (ca. 2 vol%). The matrix consists of quartz (20–30 vol%), Kfeldspar (10–20 vol%), plagioclase (10–20 vol%), muscovite (ca. 3 vol %), and biotite (ca. 2 vol%), with accessory amounts of apatite, titanite, and zircon (Fig. 3a, d). Molybdenite, chalcopyrite, and pyrite commonly accounting for ∼2 vol% with a grain size of < 1 mm across (Fig. 3e). The NE-trending Linxi Formation in the study area is unconformably overlain by Pliocene basalt in the northwest. The formation outcrops in an area covering around 11 km2, is > 760 m thick (measured in diamond-drillhole ZK463), and dips between 35° and 70° SE (Fig. 2). The irregular dips of the formation might be related to a combination of the emplacement of the porphyritic monzogranite and the movement along the Hegenshan-Heihe and Xar-Moron faults (Fig. 1). The formation consists of an upward-fining succession of a silica-rich unit at the base to shale at the top. The silica-rich unit is the result of silicification related by contact metamorphism and hydrothermal alteration associated with the emplacement of the porphyritic monzogranite at depth. The Mo mineralisation is enriched in SiO2 (No. 6 GT, 2012). As a result, the silica hornfels at the base of the Linxi Formation is richest in Mo mineralisation, including along extensional fractures. The silica-rich hornfels is characterised by a micro-crystalloblastic texture with a grain size < 0.2 mm, and consists of quartz (∼60 vol%), feldspar (∼10 vol %), biotite (∼15 vol%), chlorite (∼13 vol%), and disseminated sulfides (∼2 vol%) (Figs. 2 and 3c, f).

Cu

Cu

Mo Mo Mo Mo Mo

A-18

A-19

B-1 B-2 C-3 C-4 C-5

3.2. Structures The Bilugangan area includes NE-trending reverse faults that crosscut E-trending dextral faults (Fig. 2). The West Bilugangan Fault (WBF) is an example of a NE-trending reverse fault that is 6–13 m wide, at least 9000 m long, dips ∼60°SE, and controls the western extent of the mineralised zone in the study area. The NE-trending East Bilugangan Fault (EBF) is a ∼5600 m long normal fault forming the eastern boundary of the mineralised zone. The fault is 3–8 m wide, and dips 65°SE (No. 6 GT, 2012). Both faults and their splays were active during the Mo mineralising event providing dilatational zones controlling the location of ore and are associated with compression orientated NW-SE (Fig. 4). In addition, extensional NW-, reverse NE- and dextral Etrending faults are present between the porphyritic monzogranite and country rocks (No. 6 GT, 2012). The extensional NW-trending faults are typically ∼0.3–2.3 m thick, and form irregular surfaces dipping steeply to vertical. The dextral E-trending faults and NNW-trending sinistral faults are transtensional, dip steeply to vertical with thicknesses of around 0.3 m, are sharp, and host Mo-bearing veins in dilatational jogs trending SE. The extensional SE-trending are orientated parallel to the compression direction, and are also mineralised. The NE-trending reverse faults dip 40°-50°NW, are sharp, and are not obviously mineralised, although mineralisation is expected in horizontal jogs at depth in these faults.

Modified after No. 6 GT (2012).

125 105 175 125 125 13 ∼ 930 131 ∼ 736 55 ∼ 500 126 ∼ 621 373 ∼ 902 17 ∼ 16 13 ∼ 0 13 ∼ 0 9∼4 9∼8 12 ∼ 31 12 ∼ 5 59 ∼ 67 55 ∼ 71 55 ∼ 67

stratiform lenticular stratiform stratiform lenticular

3 ∼ 42 3 ∼ 39 19 ∼ 29 12 ∼ 22 10 ∼ 26

1.52 0.46 243 3.72 100 100 125 150 ∼ 189 9 52

lenticular

22

98.48 0.43 15,765 1.75 ∼ 28.11 450 850 170 108 ∼ 219 11 ∼ 6 48 ∼ 32

lenticular

14

2300 125 3 ∼ 622 17 ∼ 20 Mo A-1

siliceous hornfels and porphyritic monzogranite siliceous hornfels and porphyritic monzogranite siliceous hornfels and porphyritic monzogranite porphyritic monzogranite porphyritic monzogranite siliceous hornfels porphyritic monzogranite porphyritic monzogranite

56 ∼ 12

stratiform

1 ∼ 39

Angel (°) Dip (°) NE trending SE trending

Buried Depth (m) Shape Location (Exploration lines No.) Host rocks Dominant mineral

Table 1 Characteristics of main orebodies in the Bilugangan Mo deposit.

Occurrence

Length (m)

1850

Inclined Depth (m)

Thickness (m)

1.13 ∼ 250.50

218,290

Metal Resource (t)

0.083

Average Mo/Cu Grade (%)

53.44

3. Geology of the Bilugangan Mo deposit

841

Ore Geology Reviews 107 (2019) 837–852

L. Zhang, et al.

Fig. 5. Photographs showing various occurrences of mineralisation: (a) disseminated molybdenite within the porphyritic monzogranite around the quartz veinlets in Ore Section B (595 m at ZK005); (b) Mo veinlets coexisting with pyrite in the porphyritic monzogranite from Ore Section B (489 m at ZK005); (c) quartz – perthite – molybdenite veinlet in the hornfels from Ore Section A (157 m at ZK642); (d) ∼10 mm wide stockworks within the porphyritic monzogranite from the open pit of Ore Section A; (e) quartz – K-feldspar – molybdenite vein with width more than 50 mm within the porphyritic monzogranite from Ore Section B (444 m at ZK005); (f) Etrending, steeply dipping, > 100 mm wide, ivory white quartz veins coexisting with muscovite and sulfides in hornfels from the open pit at Ore Section A. Abbreviations: Qtz, quartz; Kfs, K-feldspar; Mo, molybdenite; Py, pyrite.

molybdenite, chalcopyrite and pyrite, with lesser amounts of sphalerite, wolframite, galena, and limonite. Gangue minerals include quartz, microcline, perthite, muscovite and sericite, and minor amounts of biotite, chlorite, epidote, calcite, and fluorite. The quartz veins increase in length and thickness with decreasing depth. The veins include ∼10–50 mm wide smoky grey quartz distributed extensively in the porphyritic monzogranite and adjoining hornfels, and vertical E-trending, > 100 mm wide white quartz near the ground surface in both the porphyritic monzogranite and hornfels.

3.3. Mineralisation Exploration has delineated 39 orebodies including two that are Curich in the Bilugangan area. The combined resource is 0.41 Mt @ 0.083% Mo with a cut-off grade of 0.03 wt%, and a Cu resource of 0.016 Mt @ 0.43% Cu. The richest orebodies are locally called A-1, B-1, B-2, C-3, C-4, C-5 and A-18, accounting for ∼98% of the Mo resource. The mineralisation is lenticular or stratiform extending to a depth of at least 943 m in mineralised zones A in the north, B, and C in the south (Fig. 2; Table 1). Characteristics of these mineralised sections are described below, and that of the main orebodies are summarised in Table 1. Ore Section A is the richest including 12 Mo- and two Cu-orebodies. The Mo orebodies are between 50 and 2300 m long, 3 to 650 m deep, between 1 and 250 m thick, dip 1–40° SE, and have an average grade of 0.083% Mo. The copper mineralised is 850 m long, between 100 and 220 m deep, ∼2–30 m thick, dips ∼10–25°SE, and has an average grade of 0.43% Cu (Fig. 4a; No. 6 GT, 2012). Ore Section B is located southwest of zone A and includes 11 Mo orebodies that are 10 to 930 m deep, 100 to 2300 m long, ∼2 to 150 m wide, dip between 3° and 45°SE, and have an average grade of 0.082% Mo (Fig. 4b; No. 6 GT, 2012). Ore Section C has the lowest Mo resource in the area. It is located southwest of zone B and includes 14 Mo orebodies with an average grade of 0.081% Mo. The orebodies are between 100 and 700 m long, 20 to 945 m deep, ∼1–85 m thick, and dip 5-35° SE (Fig. 4c; No. 6 GT, 2012). The orebodies deepen from zone A to C, and the Mo resource increases in the opposite direction (Fig. 4a–c). In addition, the morphology and location of the orebodies have been structurally modified making it is difficult to define the accurate location and form of the structures only from the drill core. The mineralisation in the area includes disseminated sulfides, and hydrothermal veins forming stockworks (Fig. 5a–f). Disseminated mineralisation is present in the porphyritic monzogranite at depth with minor occurrences in adjoining hornfels, especially around quartz veins that are typically < 10 mm thick. The mineralisation includes

3.4. Alteration The Bilugangan Mo mineralisation is characterised by potassic–silica – sericitic alteration and development of greisen. The alteration includes the assemblage chlorite–calcite–fluorite–clay minerals, which is not directly related to the Mo mineralisation. The central part of the porphyritic monzogranite is characterised by potassic and phyllic- alteration with an overprinting pervasive silica alteration (Fig. 4). The potassic alteration is characterised by microcline, perthite and biotite, and is commonly present at the top of the porphyritic monzogranite (Fig. 6a–c). The microcline has cross hatched twinning forming aggregates overprinting plagioclase, and is also present in fractures cutting hornfels. Perthite is intergrown with sodic plagioclase in microcline, and commonly forms strings, lenticular crystals and myrmekite, which possibly result from the exsolution of sodium from high temperature alkali in the solid state (Fig. 6b, h, m). Scaly biotite is between 2 and 5 mm across and is locally present in quartz veins in the porphyritic monzogranite (Fig. 6a, c). Greisen is also developed in this alteration and is characterized by < 10 mm long flaky muscovite in quartz-K-feldspar-molybdenite veins as aggregates or disseminating into the porphyritic monzogranite (Fig. 6f). The phyllic alteration zone contains sericite accompanied by pyrite, which has a close relationship with the Mo mineralisation, although not as rich as in the potassic alteration (Fig. 6g, h, j, k). Feldspar and biotite are variably replaced by ∼1 mm long sericite that either forms the phyllic-altered porphyritic monzogranite and hornfels or presents along 842

Ore Geology Reviews 107 (2019) 837–852

L. Zhang, et al.

(caption on next page)

843

Ore Geology Reviews 107 (2019) 837–852

L. Zhang, et al.

Fig. 6. Photographs and photomicrographs showing alterations, ore textures, and mineral assemblages of the Bilugangan Mo deposit showing: (a) barren massive quartz - K-feldspar with biotite locally presenting in porphyritic monzogranite at stage 1 (736 m at ZK305); (b) close-up of K-feldspar shown in (a) is perthite with an intergrowth of sodic plagioclase in microcline, and both feldspars are replaced by sericite; (c) barren quartz - K-feldspar vein with biotite along the edges of the quartz and K-feldspar in stage 1 (655 m at ZK005); (d) molybdenite on both sides of quartz veins coexisting with K-feldspar in stage 2 (940 m at ZK463); (e) close-up of Kfeldspar shown in (d) is microcline coexisting with muscovite, sericite and anhedral Mo; (f) locally developed greisen in silicified porphyritic monzogranite at stage 2 (192 m at ZK642); (g) quartz vein with ∼1 mm long sericite and molybdenite in potassic altered porphyritic monzogranite at stage 3 (833 m at ZK463); (h) close-up of K-feldspar shown in (g) is perthite with an intergrowth of sodic plagioclase in microcline, and both the feldspars are altered; (i) feldspar with sericite- altered along the edge and cryptocrystalline in the core from ore section B (710 m at ZK005); (j) sericite altered quartz vein has sulfides along both sides at stage 3 vein (285 m at ZK305); (k) close-up of sulfides shown in (j) are molybdenite, chalcopyrite, and pyrite; (l) chalcopyrite, sphalerite, and sericite from the quartz vein with a width > 100 mm of stage 3 (709 m at ZK005); (m) perthite with a myrmekite texture in aggregates distributed stage 3 veins (189 m at ZK642); (n) stage 4 barren quartz - calcite - fluorite veinlet crosscutting earlier stage veins in hornfels (275 m at ZK463); and (o) photomicrographs of the assemblage of quartz, calcite, and fluorite shown in (n). Abbreviations: Qtz, quartz; Kfs, K-feldspar; Per, Perthite; Bt, biotite; Mo, molybdenite; Py, pyrite; Ccp, chalcopyrite; Ms, muscovite; Ser, sericite; Ab, albite; Fl, fluorite; Ep, epidote.

progressing from Stage 1(the oldest), to Stage 4 being the youngest (Fig. 7).

3.5.1. Stage 1 Stage 1 contains the assemblage quartz–perthite–microcline(–biotite) present in the potassic-altered porphyritic monzogranite (Fig. 6a–c). The assemblage is stringy and lenticular located in 10-mm wide veins with diffuse edges. Biotite is locally present along the edges of the quartz and K-feldspar in both the porphyritic monzogranite and veins.

3.5.2. Stage 2 The second stage is characterized by 3–50 mm-wide veins containing quartz–K-feldspar–Mo–muscovite–sericite(–pyrite) in the potassic-altered porphyritic monzogranite and less commonly in the phyllic alteration zone (Fig. 6d–f). Molybdenite is usually accompanied by microcline, muscovite and sericite, with microcline accompanied by aggregates of subhedral to anhedral molybdenite and muscovite forming jagged layers along the edge of the veins. The molybdenite is also disseminated through the veins in the porphyritic monzogranite. Fig. 7. Simplified paragenetic sequence of mineralisation and gangue minerals in the Bilugangan deposit.

3.5.3. Stage 3 Stage 3 is represented by the assemblage quartz–molybdenite–chalcopyrite–myrmekitic perthite–muscovite–sericite(–pyrite–sphalerite) (Fig. 6g–m), and the assemblage is present in the phyllicaltered porphyritic monzogranite and hornfels. Molybdenite, chalcopyrite and pyrite are present as subhedral or anhedral in and along the edges of the veins, and pyrite is also disseminated in selvages near the veins.

the edges of the quartz vein. Locally, some relatively weak sericitic altered rocks are yellow – green coloured, which were easy to be mistaken as the propylitic alteration according to previous studies, but are actually sericite- altered feldspar containing cryptocrystalline cores under a microscope (Fig. 6i; No 6 GT, 2012; Tang et al., 2012; Li et al., 2016a,b). Silica alteration overprints the other alteration zones forming siliceous rocks and quartz veins hosting Mo mineralization (Fig. 6f).

3.5.4. Stage 4 The last stage in the hydrothermal alteration is not mineralised and characterised by 2–30 mm wide veins of quartz–fluorite–calcite(–sericite–muscovite) in the propylitic-altered porphyritic monzogranite and hornfels (Fig. 6n, o).

3.5. Paragenesis of the mineralisation The following interpretation of the paragenesis of the Bilugangan Mo deposit is based on field and microscopic observations, and crosscutting relationships. The sequence is here divided into four stages Table 2 Re-Os dating of molybdenite from the Bilugangan Mo deposit. Sample No.

BL-1 BL-3 BL-6–1 BL-6–2 BL-9–2 BL-9–1 BL-10–2

Drill hole

ZK1138 ZK732 ZK328 ZK328 ZK328 ZK328 ZK736

Depth

Weight

Re

2σ

187

(m)

(g)

(ng/g)

(abs)

160 329 622 622 622 622 90

0.01054 0.01044 0.01070 0.01017 0.01096 0.05006 0.01178

87,010 118,645 33,310 41,457 120,708 108,962 16,046

0.8 1.1 0.3 0.3 1.2 1.6 0.1

844

2σ

187

(ng/g)

(abs)

54,687 74,571 20,936 26,056 75,867 68,485 10,085

0.5 0.7 0.2 0.2 0.7 1.0 0.1

Re

Os

2σ

Age

2σ

(ng/g)

(abs)

(Ma)

(abs)

216.6 295.1 83.41 104.0 302.1 271.0 39.87

1.7 2.4 0.73 0.9 2.4 3.0 0.36

237.3 237.1 238.7 239.2 238.6 237.0 236.8

3.4 3.4 3.4 3.5 3.6 4.8 3.6

Ore Geology Reviews 107 (2019) 837–852

L. Zhang, et al.

Fig. 8. Bilugangan molybdenite: (a) Re-Os weighted mean age; and (b) isochron age.

was performed using a TJA X-Series ICP-Ms (Thermo Electron Corporation, USA) at the National Research Centre of Geoanalysis, Chinese Academy of Geological Sciences (CAGS), China. The detailed analytical procedures were described by Du et al. (1994, 2004). The molybdenite standard GBW04435 (HLP) yielded a model age of 221 ± 3 Ma during our analytical session, which is identical within error to the expected value of 221 ± 6 Ma (Du et al., 2004). Model ages were calculated following the equation: t = [ln (1 + 187Os/187Re)]/λ, where λ is the decay constant of 187Re, 1.666 × 10−11 yr−1 (Smoliar et al., 1996). Uncertainties in Re-Os model age calculations include: weighing for spike and sample; 187Re decay constant; spike calibration; and mass spectrometry analysis. Isochron age and weighted mean ages were calculated using the Isoplot 3.0 program (Ludwig, 2003). All uncertainties are < 5% at the 95% level of confidence.

Table 3 Sulfur isotope compositions (δ34SV-CDT) of the sulfide samples from the Bilugangan deposit. Sample No.

ZK305-15-1 ZK305-15-2 ZK652-35 ZK305-9 ZK652-34-1 ZK652-34-2 ZK463-30-1 ZK463-30-2 ZK005-30-1 ZK005-30-2 ZK005-43 ZK305-13-1 ZK305-13-2 ZK005-18 ZK005-27-1 ZK005-27-2 ZK652-38-1 ZK652-38-2 ZK005-32-1 ZK005-32-2 ZK005-32-3 ZK463-23-1 ZK463-23-2 ZK305-3-1 ZK305-3-2 ZK005-59 ZK005-17 ZK463-31-1 ZK463-31-2 ZK005-55-1 ZK005-55-2 ZK652-13-1 ZK652-13-2

Location

Stage

Drill hole

Depth(m)

ZK305 ZK305 ZK652 ZK305 ZK652 ZK652 ZK463 ZK463 ZK005 ZK005 ZK005 ZK305 ZK305 ZK005 ZK005 ZK005 ZK652 ZK652 ZK005 ZK005 ZK005 ZK463 ZK463 ZK305 ZK305 ZK005 ZK005 ZK463 ZK463 ZK005 ZK005 ZK652 ZK652

481 481 463 341 454 454 940 940 444 444 601 406.5 406.5 405 416.5 416.5 483 483 472 472 472 832.5 832.5 283 283 785 398.5 942 942 709 709 150 150

δ34S value (‰) Mo

2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3

Ccp

Py

1.8 2.8 2.5 3 3.3 4.1 2 3.8 2.6 3.8 2.8

4.2. S-Pb isotopies analytical methods

1.8 3.1 3.4

Twelve molybdenite samples, six chalcopyrite samples, and fifteen pyrite samples were collected from mineralised veins in Stages 2 and 3 for analyses of S- and Pb-isotopes analyses at the Analytical Laboratory of Beijing Research Institute of Uranium Geology. Also included are eight samples of porphyritic monzogranite from each ore section, and two hornfels samples for whole rock Pb-isotope analyses (Fig. 4). The sulfur-isotopic composition was measured using a Delta V Plus mass spectrometer on SO2 obtained by placing the sulfide-CuO composite into a vacuum system (0.1 Pa) heated to 980 °C (Robinson and Kusakabe, 1975; Liu et al., 2013). The sulfide isotope ratios are reported as δ34S relative to the Canyon Diablo Troilite (CDT), and the national standards GBW04414 and GBW04415 were used as external standards with an analytical precision of ± 0.2‰. Lead isotope analyses were completed using an ISOPROBE-T TIMS, and corrected against the values of NBS SRM 981 standard, and the analytical errors for 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios were < 0.05%.

2.6 2.6 3.5 3.6 2.8 2.6 3 1.5 3.3 4.3 1.7 2.1 2.8 2.1 3.9 2 2 2.7 4.2

Mo, molybdenite; Ccp, chalcopyrite; Py, pyrite.

4.3. H-O isotopies analytical methods

4. Sampling and analytical methods

Fifteen gangue quartz samples of quartz, quartz-sulfide, and quartzcalcite veins from Stages 1 to 4 were collected for hydrogen and oxygen isotope analyses using a MAT 253EM mass spectrometer at the Institute of Mineral Resources of CAGS, Beijing. Hydrogen was converted from water in fluid inclusions by reacting with chromium powder at 850 °C, and the water was released by heating the quartz to approximately 500 °C in an induction furnace (Wan et al., 2005). Oxygen was liberated from quartz by reacting with BrF5 and converted to CO2 on a platinumcoated carbon rod (Clayton and Mayeda, 1963). The δ18OQuartz and

4.1. Molybdenite Re–Os isotope analysis Seven molybdenite samples were collected from diamond-drillholes ZK732, ZK736, ZK328 and ZK1138 in the ‘A’ mineralised zone for Re-Os isotopic analysis (Fig. 2; Table 2). All the samples are from quartzmolybdenite veins containing muscovite or chalcopyrite. The analysis

845

Ore Geology Reviews 107 (2019) 837–852

L. Zhang, et al.

Table 4 Lead isotope compositions of sulfides from the Bilugangan Mo deposit. Sample No.

ZK305-15-1 ZK305-15-2 ZK652-35 ZK305-9 ZK652-34-1 ZK652-34-2 ZK463-30-1 ZK463-30-2 ZK005-30-1 ZK005-30-2 ZK005-43 ZK305-13-1 ZK305-13-2 ZK005-18 ZK005-27-1 ZK005-27-2 ZK652-38-1 ZK652-38-2 ZK005-32-1 ZK005-32-2 ZK005-32-3 ZK463-23-1 ZK463-23-2 ZK305-3-1 ZK305-3-2 ZK005-59 ZK005-17 ZK463-31-1 ZK463-31-2 ZK005-55-1 ZK005-55-2 ZK652-13-1 ZK652-13-2

Location Drill hole

Depth (m)

ZK305 ZK305 ZK652 ZK305 ZK652 ZK652 ZK463 ZK463 ZK005 ZK005 ZK005 ZK305 ZK305 ZK005 ZK005 ZK005 ZK652 ZK652 ZK005 ZK005 ZK005 ZK463 ZK463 ZK305 ZK305 ZK005 ZK005 ZK463 ZK463 ZK005 ZK005 ZK652 ZK652

481 481 463 341 454 454 940 940 444 444 601 406.5 406.5 405 416.5 416.5 483 483 472 472 472 832.5 832.5 283 283 785 398.5 942 942 709 709 150 150

Stage

Analyzed mineral

206

Pb/204Pb

2σ

207

Pb/204Pb

2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3

Ccp Py Ccp Mo Mo Py Mo Py Mo Py Mo Ccp Py Py Ccp Py Mo Py Mo Ccp Py Mo Py Mo Py Py Py Mo Py Mo Ccp Mo Py

18.678 18.618 18.295 18.561 18.581 19.576 18.411 18.389 18.619 18.751 18.448 18.364 18.409 18.767 18.883 18.758 18.866 18.556 18.739 18.609 18.517 18.876 18.694 18.708 18.632 18.561 18.627 18.475 18.747 18.456 18.439 18.667 18.36

0.002 0.001 0.001 0.002 0.002 0.004 0.001 0.002 0.002 0.003 0.003 0.002 0.002 0.003 0.003 0.002 0.004 0.002 0.003 0.004 0.003 0.003 0.007 0.001 0.005 0.002 0.003 0.003 0.002 0.006 0.003 0.002 0.002

15.595 15.575 15.535 15.549 15.575 15.661 15.547 15.599 15.571 15.626 15.611 15.563 15.604 15.627 15.628 15.6 15.602 15.662 15.579 15.577 15.577 15.596 15.594 15.653 15.603 15.593 15.591 15.608 15.583 15.543 15.551 15.569 15.575

2σ

208

Pb/204Pb

2σ

0.002 0.001 0.001 0.002 0.003 0.003 0.001 0.001 0.001 0.005 0.003 0.002 0.001 0.003 0.003 0.002 0.004 0.002 0.003 0.003 0.002 0.002 0.003 0.002 0.004 0.002 0.002 0.003 0.002 0.005 0.002 0.002 0.002

38.411 38.292 38.066 38.256 38.379 38.416 38.162 38.314 38.329 38.441 38.39 38.166 38.298 38.453 38.653 38.472 38.278 38.5 38.286 38.115 38.251 38.408 38.313 38.497 38.321 38.312 38.371 38.358 38.344 38.149 38.168 38.126 38.193

0.004 0.003 0.005 0.004 0.008 0.008 0.003 0.003 0.003 0.011 0.008 0.004 0.004 0.01 0.006 0.005 0.012 0.005 0.008 0.007 0.005 0.008 0.014 0.004 0.011 0.005 0.006 0.009 0.004 0.011 0.006 0.004 0.004

Mo, molybdenite; Ccp, chalcopyrite; Py, pyrite.

δDfluid values were normalised using the V-SMOW standards with analysis accuracy better than ± 2‰ for δDfluid and ± 0.2‰ for δ18OQuartz. Several justifications, including diffusion estimation, equilibrium establishment and temperature estimations, are necessary to be made before using δ18OQuartz values to trace fluid evolution. The ∼0.5 cm grained quartz in the veins probably precipitated in a period longer than 20 yr, and therefore the O isotope fractionation between quartz and water occurred under equilibrium conditions (Li et al., 2018). Therefore, the oxygen isotopic compositions of hydrothermal fluids (δ18Ofluid) could be calculated using the equation of Clayton et al. (1972), 1000lnαQ-H2O = 3.38 × 106 × T−2-3.4, together with the measured δ18OQuartz values and the formation temperature of every stage. We used the correspondingly average fluid inclusion homogenisation temperatures of every stage in the Mo mineralisation that could roughly represent the lowest formation temperatures for each stage. The diffusion estimation is impossible to make due to a lack of the δ18OZircon values at Bilugangan.

interpreted as the age of the molybdenite. 5.2. S-Pb isotopes The sulfur isotopic compositions of 33 sulfide samples from Stages 2 and 3 at the Bilugangan deposit are given in Table 3. Twelve molybdenite, six chalcopyrite, and 15 pyrite samples have δ34S values of 1.5–4.3‰ for molybdenite, 1.8–2.6‰ for chalcopyrite, and 1.7–4.2‰ for pyrite. The results of 33 sulfide samples and ten whole rock samples chosen for Pb isotopic geochemistry are listed in Tables 4 and 5. Sixteen sulfide samples from Stage 2 have relatively concentrated Pb isotopic compositions, with 206Pb/204Pb ratios between 18.295 and 19.576, 207 Pb/204Pb ratios between 15.535 and 15.661, and 208Pb/204Pb ratios between 38.066 and 38.653. Seventeen sulfide samples from Stage 3 also have relatively concentrated Pb isotopic compositions, with 206 Pb/204Pb ratios of 18.36–18.876, 207Pb/204Pb ratios of 15.543–15.662, and 208Pb/204Pb ratios of 38.115 and 38.5. The porphyritic monzogranite has 206Pb/204Pb ratios of 18.274–18.58, 207 Pb/204Pb ratios of 15.557–15.593, and 208Pb/204Pb ratios of 38.1–38.228. Hornfels samples from the Linxi Formation have 206 Pb/204Pb ratios of 18.456–18.572, 207Pb/204Pb ratios of 15.572–15.58, and 208Pb/204Pb ratios of 38.214–38.239.

5. Results 5.1. Molybdenite Re-Os dating Seven Re-Os isotopic analyses of molybdenite samples are presented in Table 2. The total Re assays are between 16 and 121 ppm, and 187Os assays are between 39 and 302 ppb. The model ages range from 239 ± 4 to 237 ± 4 Ma, yielding a weighted mean age of 238 ± 1 Ma with a mean square weighted deviation (MSWD) of 0.29, and an isochron age of 238 ± 2 Ma with a MSWD of 0.49(Fig. 8a, b). These Middle Triassic dates are the same within error and are

5.3. H-O isotopes The hydrogen and oxygen isotope data determined on quartz from the four Stages are given in Table 6. The δ18O values for fifteen gangue quartz samples from Stages 1 to 4 range from 9 to 13.3‰. The calculated δ18Ofluid values for quartz from Stage 1 are 4.2–5.2‰, with the 846

Ore Geology Reviews 107 (2019) 837–852

(206Pb/204Pb)i

18.495 18.505 18.580 18.363 18.480 18.457 18.497 18.274 18.456 18.572 15.588 15.586 15.593 15.567 15.581 15.571 15.585 15.557 15.572 15.580

(208Pb/204Pb)i

(207Pb/204Pb)i

L. Zhang, et al.

6. Discussion

Molybdenite from the Bilugangan deposit has a Re-Os isochron age of 238 ± 2 Ma, which is identical with the Re-Os weighted mean age (Li et al., 2016a,b). These dates are also coeval, within error, with the 241 ± 3 Ma emplacement age of porphyritic monzogranite (Liu et al., 2012a). This is indicative of genetic relationship between the mineralisation and the spatially related granitic intrusions. There are many Mesozoic Mo deposits in eastern CAO and at the northern margin of NCB. These deposits are interpreted as being associated with tectonic events during the Triassic (250–200 Ma) and Jurassic to Cretaceous (180–130 Ma) (Zeng et al., 2012; Chen et al., 2017b). Molybdenite deposits dated between 250 and 200 Ma are located along the northern margin of the NCB (Fig. 1; Cai et al., 2011a,b; Liu et al., 2012b; Meng et al., 2013; Sun et al., 2013; Jiang et al., 2014; Duan et al., 2015). The Jurassic to Cretaceous deposits are widely distributed in eastern CAO and northern NCB. There are no Triassic deposits in eastern CAO except for the large Bilugangan deposit and two medium- to small- sized deposits. Bilugangan is the oldest and the only known large Triassic Mo deposit in eastern CAO, indicating that the prospectivity for large Mo in this region has been underestimated in the past.

206

19.039 19.396 19.525 18.885 19.283 19.122 18.730 18.842 18.716 19.376 0.002 0.002 0.001 0.002 0.002 0.001 0.002 0.002 0.004 0.006

6.2. Source of mineralisation The Bilugangan porphyry Mo deposit has a narrow δ34SVCDT range of 1.5–4.3‰ (Fig. 9a). This is similar to the δ34SVCDT value close to 0 ± 5‰ for magmatic sources of sulfur, and more constrained than those of sedimentary rocks with values of −50 to 20‰ (Ohmoto and Rye, 1979; Seal, 2006; Hoefs, 2009). The source of the sulfur associated with the mineralisation at Bilugangan is therefore interpreted to have a unique magmatic and hydrothermal source with minor contamination from a sedimentary source. Porphyry Mo deposits include the Climax- and Endako-types, which correspond broadly with Sillitoe's (1980) classification of rift-related and subduction-related porphyry Mo deposits. Furthermore, the δ34S values for the Bilugangan deposit are like those of the Climax-type deposits with values 2.5–5.3‰, and collision-type Mo deposits in China with values of 2.1–5.9‰. This is in contrast with the Endako-type Mo deposits with a wider and overlapping range of values between −4 and 4.6‰ (Fig. 9; Stein and Hannah, 1985; Wareham and Rice, 1998; Ni et al., 2015; Wang et al., 2017). Our data are also similar to those of porphyry-type Mo deposits in the Great Hingan Range and northern margin of NCB, such as 4.3–6.3‰ for Dasuji, 1.1–3.7‰ for Chagandeersi, and 2.7–3.4‰ for Chaganhua (Liu, 2013; Wu, 2015; Zhang and Liang, 2017). The lead isotopic compositions of sulfides at Bilugangan plot closely together in the 207Pb/204Pb vs 206Pb/204Pb and 208Pb/204Pb vs 206 Pb/204Pb diagrams presented in Fig. 10(a, b). There is a degree of overlap with the recalculated Pb-isotopic compositions of the porphyritic monzogranite and hornfels in the Linxi Formation using the 240 Ma date (Table 5). This indicates that the lead in the sulfides is derived from both the monzogranite and hornfels. The values plotting out of the fields defined by the porphyritic monzogranite and the hornfels, probably relate to an unknown lead source.

Porphyritic granite

hornfels 309 554

ZK005 ZK005 ZK305 ZK063 ZK063 ZK063 ZK005 Open pit ZK463 ZK463 ZK005-26 ZK005-29 ZK305-30 ZK063-1 ZK063-2 ZK063-3 ZK005-4 BL16-26 ZK463-7 ZK463-14

Depth (m) Drill hole

443 439 707 831 836 804 233

B B B C C C B A C C

Ore section

208

38.610 38.682 38.716 38.416 38.562 38.531 38.367 38.472 38.653 39.411

Pb/204Pb

2σ

0.004 0.004 0.004 0.005 0.004 0.003 0.006 0.005 0.009 0.015

207

15.616 15.631 15.641 15.594 15.622 15.605 15.597 15.586 15.585 15.621

Pb/204Pb

2σ

Pb/204Pb

2σ

0.002 0.002 0.002 0.002 0.003 0.002 0.002 0.003 0.005 0.007

240 240 240 240 240 240 240 240 240 240

Age (Ma)

41.8 38.9 42.6 59.6 41.1 44 45.7 35.5 23.1 7.8

Pb (ppm)

23.5 26.1 27.3 24.3 24.9 24.3 11.6 13.7 13.3 12

Th (ppm)

9.71 14.8 17.2 13.3 14.1 12.5 4.55 8.61 2.57 2.68

U (ppm)

38.182 38.171 38.228 38.105 38.100 38.110 38.174 38.178 38.214 38.239

6.1. The oldest large porphyry Mo deposit in eastern CAO

Analyzed rock Location Sample No.

Table 5 Whole-rock Pb isotopic compositions of samples from the Bilugangan Mo deposit.

δDfluid values are between −106 and −96‰. The calculated δ18Ofluid values of quartz from Stage 2 range from 1.3 to 2.1‰ and Stage 3 range from 0.5 to 1.5‰, with the δDfluid values between −104 and 90‰ for Stage 2, and −99 and −60‰ for Stage 3. The calculated δ18Ofluid values for the Stage 4 quartz are 1.9‰, and the δDfluid values are between −115 and −113‰.

847

Ore Geology Reviews 107 (2019) 837–852

L. Zhang, et al.

Table 6 The hydrogen and oxygen isotope compositions (‰) of samples from the Bilugangan Mo deposit. Sample No.

ZK005-50 ZK005-37 ZK005-41 ZK463-13 ZK642-11 ZK305-15 ZK005-30 ZK305-13 ZK652-38 ZK005-55 ZK642-8 ZK305-8 ZK652-13 BL16-14 BL16-24

Location Drill hole

Depth (m)

ZK005 ZK005 ZK005 ZK463 ZK642 ZK305 ZK005 ZK305 ZK652 ZK005 ZK642 ZK305 ZK652 Open pit Open pit

661 528 580 628 198 481 444 406.5 483 709 189 334 150

Stage

Vein mineralogy

Th(°C)

δ18OQuartz (‰)

δ18Ofluid (‰)

δDfluid (‰)

1 1 1 1 2 2 2 2 3 3 3 3 3 4 4

Qtz, Qtz, Qtz, Qtz, Qtz, Qtz, Qtz, Qtz, Qtz, Qtz, Qtz, Qtz, Qtz, Qtz, Qtz,

320 320 320 320 260 260 260 260 259 259 259 259 259 205 205

10.8 10.4 10.5 11.4 9.8 10.1 10.6 9.9 9.2 9.8 9.1 10 9 13.3 13.3

4.6 4.2 4.3 5.2 1.3 1.6 2.1 1.4 0.7 1.3 0.6 1.5 0.5 1.9 1.9

−102 −100 −96 −106 −90 −104 −101 −96 −79 −60 −94 −96 −99 −113 −115

Kfs, Bt Kfs Kfs Kfs Bt, Ccp Mo, Py Kfs, Mo Kfs, Mo, Ccp Mo Mo, Ccp, Py Ab, Mo Mo, Ccp, Py Ser, Mo, Py Fl, Ser Fl

Qtz, quartz; Kfs, K-feldspar; Bt, biotite; Mo, molybdenite; Py, pyrite; Ccp, chalcopyrite; Ser, sericite; Ab, albite; Fl, fluorite; Th, the average homogenization temperatures of fluid inclusions from each stage in the Bilugangan deposit (unpublished data).

Fig. 9. Diagrams: (a) Histogram of sulfur isotopic composition of the Bilugangan deposit; and (b) compilation of sulfur isotope compositions for sulfides from different source rocks, deposits in various tectonic settings, and Triassic Mo deposits along the north margin of the North China Block. The data for the Bilugangan deposit are from this study, and others are from Ohmoto and Rye (1979), Stein and Hannah (1985), Wareham and Rice (1998), Hoefs (2009), Liu (2013), Ni et al. (2015), Wu (2015), Wang et al. (2017), and Zhang and Liang (2017).

6.3. Source of mineralised fluids

This phenomenon is also observed in early stages of many other porphyry-type Mo deposits, such as Endako with a δ18Dfluid value of −125 to −150‰ for stockwork quartz (Selby et al., 2000). Other examples include Xishadegai with δ18Dfluid values between −120 and 108‰, and Chaganhua with δ18Dfluid values of −110 to 95‰ (Liu, 2013; Sun, 2016). Compared with the values for Stage 1, the samples from Mo mineralised veins have relatively higher δDfluid values ranging from −104 to −90‰ for Stage 2, −99 to −60‰ for Stage 3, and lower δ18Ofluid values ranging from 1.3 to 2.1‰ for Stage 2, and 0.5 to 1.5‰ for Stage 3. These data plot between the primary magmatic water box and the meteoric water line shown in Fig. 11. The implication is that the mineralising fluids associated with Stages 2 and 3 have both magmatic and meteoric sources. In this scenario, the mixture of fluid sources can explain the presence of the highly radioactive Pb in the sulfides sourced from the wall rocks. The δDfluid values of barren veins in Stage 4 range from −115 to −113‰, with a δ18Ofluid value of 1.9‰, which is slightly higher than those of Stages 2 and 3. One explanation for the high δ18Ofluid value is due to wallrock reaction between the evolved fluid and porphyritic

The Stage 1 quartz-K-feldspar veins at Bilugangan have a relatively narrow δ18Ofluid range of 4.2–5.2‰, which is slightly lower than that of primary magmatic water with values 5.5–10‰ (Taylor, 1974). In addition, the δDfluid values for the Stage 1 veins are −106 to −96‰, which are significantly lower than the values of −80 to −40‰ for primary magmatic water, and might record in situ degassing of a parental magma (Fig. 11; Taylor, 1974). Degassing of a magma takes place during its cool with the possibility that the composition of hydrogen isotopes in fluid leaving a magma will be different from fluid in a magma (Taylor et al., 1983). For most hydrous silicate minerals at magmatic temperatures, deuterium is partitioned into the vapour during the degassing progress and the fractionation effect for oxygen isotopes is small (Taylor et al., 1983). As a result, the loss of vapour at a magmatic temperature will progressively deplete the magma in deuterium without significantly affecting the oxygen isotope composition (Taylor et al., 1983). In addition, the δDfluid values of a fluid exsolved from a parental magma will be progressively lower in δDfluid whereas the δ18Ofluid values remain relatively constant (Meinert et al., 2003). 848

Ore Geology Reviews 107 (2019) 837–852

L. Zhang, et al.

Fig. 10. Plots for molybdenite, chalcopyrite, pyrite, porphyritic monzogranite, and hornfels in the Linxi Formation at the Bilugangan deposit: (a) 207Pb/204Pb versus 206 Pb/204Pb diagram, and (b) 208Pb/204Pb versus 206Pb/204Pb diagram. Initial isotope ratios of the porphyritic monzogranite, and hornfels in the Linxi Formation are calculated for a date of 240 Ma. Mantle and crust derived igneous rocks data of the south Great Hingan Range, and the Paleozoic mafic rocks data from NE China are from Guo et al. (2010).

fluid, rather than being continuous, and the gradual decreasing trend of the values are balanced with the input of meteoric water (Li et al., 2018). In this process, the mineralising potential of the hydrothermal fluids reduces progressively, because of the decreasing magmatic component (Li et al., 2018). The δ18Ofluid values at Bilugangan are not characteristic of an intact pulsed magmatic – hydrothermal process due to a lack of an absolute time framework of the Mo mineralisation, but the high δ18Ofluid value in Stage 4 may provide a good example for this phenomenon that could be a promising direction for future work in this deposit.

6.4. Genesis of the Bilugangan Mo deposit The Bilugangan Mo deposit has characteristics of a porphyritic-type deposit, which includes its spatially and temporally relationship with the porphyritic monzogranite. The chronological relationship is given by the ca. 238 Ma age for both the mineralisation and porphyritic monzogranite (detailed above). In addition, the genetic relationship between the mineralisation and monzogranite is indicated by the presence of disseminated molybdenite, chalcopyrite, and pyrite in the porphyritic monzogranite and quartz veins containing the assemblage quartz–microcline–perthite–white mica–sulfides in the bordering hornfels. Another indication for a genetic relationship is the concentric alteration zones with the non-mineralised high-temperature potassic alteration being overprinted by lower-temperature mineralised phyllic alteration. The H and O isotopic data indicate that the Mo mineralisation is closely associated with an in-situ degassing magma generating the fluids in the deposit area, which were later modified with the input of meteoric water. Finally, the S and Pb isotopic compositions indicated that the mineralisation and fluid were derived from a magmatic hydrothermal system and the country rocks.

Fig. 11. The δ18Ofluid and δD values of mineralising fluids at the Bilugangan Mo deposit. The metamorphic water and primary magmatic water fields, and the meteoric water line are from Taylor (1974). Abbreviation: SMOW, Standard Mean Ocean Water.

monzogranite. The alternative is that the high δ18Ofluid values for the Stage 4 mineralisation is probably related pulsating magmatic – hydrothermal fluids during a single cooling magmatic chamber. Recent studies shows that periodic fluctuations in δ18Ofluid values, in an absolute time framework, is related to intermittent pulses of magmatic

Fig. 12. Conceptual model showing the tectonic setting of the Middle Triassic Bilugangan Mo deposit.

849

Ore Geology Reviews 107 (2019) 837–852

L. Zhang, et al.

hydrous alteration might be related to a magmatic source in the crust and mantle related to an oceanic plate subduction setting (Chen et al., 2017a). The K-CO3-F alteration observed at Bilugangan is typical of the synto post collision Dabie-type porphyry Mo(-Cu) deposits sourced from the middle crust (e.g. Audétat and Li, 2017). In addition, the δ34S values 1.5–4.3‰ for molybdenite at Bilugangan are in the range −2.9 to 10.7‰ for the Dabie-type deposits, which are like granites and porphyry Mo deposits worldwide. Examples are the Climax-type Mo deposits (0.8–6.8‰), which are typical of the combined magmatic and hydrothermal systems (Carten et al., 1993; Hoefs, 2009; Chen et al., 2017a). The ca. 238 Ma age of the Bilugangan deposit and its collisional setting is synchronous with the Triassic Indosinian Orogeny, which is an important tectonic event that extends from the northern margin of NCB to the southern part of the South China Block (e.g. Faure et al., 2003, 2016; Kusky et al., 2007; Li et al., 2007).

The Middle Triassic Mo mineralisation at Bilugangan is the largest Triassic Mo deposit discovered in the eastern part of CAO. Although there is an uncertainty of when the Paleo-Asian Ocean closed between NCB and CAO, it is commonly accepted that the closure took place during the late Paleozoic to early Triassic along the Solonker Suture (e.g. Xiao et al., 2009; Wu et al., 2011; Han et al., 2012). If this timing is accurate, the Mo mineralisation at Bilugangan was deposited after the closure of the Paleo-Asian Ocean (Fig. 12). Given that many Mo deposits in the southern part of the Great Hingan Range are dated between 180 and 130 Ma, the ca. 238 Ma age for the Bilugangan Mo deposit shows that this region is also prospective for Triassic mineralisation. This interpretation is strengthened by the presence of the Baiyinnuoer skarn-type Pb-Zn deposit with a U-Pb zircon age of ca. 240 Ma related to the emplacement of a granodiorite, and the Gaogangshan with a Re–Os molybdenite age of ca. 235 Ma and the Laojiagou Mo deposit with a Re–Os molybdenite age of ca. 250 Ma (Zhang et al., 2014; Duan et al., 2015; Jiang et al., 2017). In addition, some Triassic intrusions in eastern CAO could also be prospective for Mo mineralisation, including ca. 247–222 Ma in age around Southern Great Hingan Range, from 222 to 200 Ma within the Jiamusi Terrane and between 252 and 241 Ma in the south of Songliao Terrane (Wu et al., 2011).

7. Conclusions New Re-Os molybdenite dating, H–O–S–Pb isotopic systematics and detailed geological field work have led us to the following conclusions. The Bilugangan Mo deposit is hosted by a ca. 240 Ma porphyritic monzogranite and accompanying hornfels, and is characterised by disseminated sulfides in the monzogranite, and veins locally forming stockworks in the surrounding hornfels. Four vein sets representing hydrothermal alteration are present at the deposit with the second and third sets associated with Mo mineralisation. The hydrothermal alteration at the deposit includes the non-mineralised potassic Stage 1 alteration succeeded by the mineralised potassic–phyllic Stage 2 and subsequent phyllic Stage 3 alteration, and the overprinting the nonmineralised Stage 4 silica alteration. The combined characteristics of the concentric alteration zones and the S-Pb isotopic systematics indicate that Bilugangan is a collisionrelated Dabie-type deposit, and is derived from a source including magmatic and country rocks. Analyses of H-O isotopes indicate that the mineralising fluids were probably generated from in-situ degassing of a magmatic source in the early ore-forming stage and were later mixed with meteoric fluid during Stage 3. The Re-Os molybdenite isochron age of 238 ± 2 Ma is identical, within error, to the U-Pb zircon date of ca. 240 Ma for the porphyritic monzogranite. This, and the characteristics of the relationship between the Bilugangan deposit and monzogranite summarised above, indicates that the deposit is genetically related to the monzogranite. The date also shows that the deposit is the oldest large porphyry Mo deposit in eastern CAO, and indicates that this region is also prospective for Triassic mineralisation. The mineralisation has a syn- to post-collisional setting related to the widespread Triassic Indosinian Orogeny, which extended from the northern margin of NCB to the southern part of the South China Block.

6.5. Comparison of Bilugangan with other porphyry Mo deposits Porphyry Mo deposits have been discovered throughout the Pacific Rim, with China containing the highest resources in 2016 (USGS, 2016). Deposits of this type are found in a wide range of tectonic settings including subduction, rift, and collisional settings. Examples are the subduction-type Endako deposit in North America developed in continental arcs, Climax rift-type deposit developed in back-arc or intracontinental rifts, and the collisional type at the Tangjiaping Mo deposit of Dabie Shan in eastern China (e.g. Selby et al., 2000; White et al., 1981; Wang et al., 2017). Giant high-grade deposits are invariably related to transitional (compression to extensional) tectonic settings (e.g. Keith et al., 1993; Ludington and Plumlee, 2009; Chen et al., 2017a). Given that Mo was deposited at Bilugangan after the closure of the Paleo-Asian Ocean, as discussed above, we proposed that the deposit was formed in post – collisional compress to extension transitional tectonic setting that caused decompression and geotherm-increasing and thereby resulted in the formation of mineral deposits (Chen et al., 2017b). On passing, the age of the mineralisation potentially gives us an approximate age of the ocean’s closure. Many giant Mo deposits, such Climax, consist of closely spaced orebodies located in domical structures developed over cupola-like intrusions (White et al., 1981; Ludington and Plumlee, 2009). Bilugangan, in contrast, consists of many small lenticular or stratiform shaped orebodies located above and in irregular-shaped stocks of monzogranite (with Ore Section A being the richest and located furthest NE). The orebodies and porphyritic monzogranite stocks are in contact with hornfelsed and hydrothermally altered sandstone and shale where the monzogranite forms sills. This indicates that the metamorphosed sandstone acted as a conduct for the hydrothermal fluid during the Mo deposition. The Mo deposits with a continental-arc setting are characterised by potassic, phyllic, argillic, and propylitic alteration. Deposits with continental-collision settings are characterised by anhydrous alteration. This includes the introduction of K-CO3-F, and less commonly by the presence of hydroxyl-bearing minerals such as clay, sulfates, ammonium-bearing minerals, phyllosilicates, iron oxides, carbonates, and a wide range of silicates found in phyllic and propylitic alteration zones (White et al., 1981; Selby et al., 2000; Chen et al., 2017a). These types of alteration are thought to indicate variations in ore-associated porphyritic granites and their magma sources, where anhydrous alteration is indicative of a crustal source for the magma and mineralisation, and

Acknowledgements This study is financially supported by the Chinese National Key Research and Development Program, China, (Grant No. 2017YFC0601303), the Chinese Academy of Geological Sciences Research Fund, China, (Grant No. YYWF201715), the China Geological Survey Project, China, Grant No. 121201103000150006, the State Basic Research Program of China, China, (Grant No. 2013CB429805), National Natural Science Foundation of China (NSFC), China, (Grant No. 41273061, 41873051), and Basic Work Program for Science and Technology, China, (Grant No. 2014FY121000). We are deeply grateful for the Jindi Mining Co. Ltd. for permission to study the area around the Bilugangan deposit and take samples from the mine area. 850

Ore Geology Reviews 107 (2019) 837–852

L. Zhang, et al.

References

Li, J.J., Tang, W.L., Fu, C., Li, C., Qu, W.J., Zhang, T., Wang, S.G., Dang, Z.C., Zhou, Y., Zhao, L.J., 2016a. Re-Os isotopic dating of molybdenites from the Bilugangan porphyry Mo deposit in Abag Banner, Inner Mongolia, and its geological significance. Geol. Bull. China 35 (4), 519–523 (in Chinese with English abstract). Liu, Y.F., 2013. Metallogenic Study of Chaganhua Porphyry Mo deposit in Inner Mongolia: Contribution of Subduction- Modified Fertile Magma Source and Postcollision Extensional Tectonic Setting. China Academy of Geological Sciences PhD Thesis (in Chinese with English abstract). Liu, H.B., Jin, G.S., Li, J.J., Han, J., Zhang, J.F., Zhang, J., Zhong, F.W., Guo, D.Q., 2013. Determination of stable isotope composition in uranium geological samples. World Nucl. Geosci. 30 (3), 174–179 (in Chinese with English abstract). Liu, Y.F., Nie, F.J., Jiang, S.H., Hou, W.R., Liang, Q.L., Zhang, K., Liu, Y., 2012a. Geochronology of Zhunsujihua molybdenum deposit in Sonid Left Banner, Inner Mongolia, and its geological significance. Miner. Deposits 31 (1), 119–128 (in Chinese with English abstract). Liu, Y., Nie, F.J., Fang, J.Q., 2012b. Isotopic age dating of the alkaline intrusive complex and its related molybdenum polymetallic deposit at Hekanzi, western Liaoning Province. Miner. Deposits 31 (6), 1326–1336 (in Chinese with English abstract). Liu, Y., Nie, F.J., Liu, Y.F., Hou, W.R., 2012c. Zircon SHRIMP U-Pb dating and geological significance of granite in the Baogeda Ula Mo(W) mining area, Inner Mongolia, China. Acta Petrol. Sin. 28 (2), 401–408 (in Chinese with English abstract). Liu, W., Siebel, W., Li, X.J., Pan, X.F., 2005. Petrogenesis of the Linxi granitoids, northern Inner Mongolia of China: constraints on basaltic underplating. Chem. Geol. 219, 5–35. Liu, J.M., Zhang, R., Zhang, Q.Z., 2004. The regional metallogeny of Da Hinggan Ling, China. Earth Sci. Front. 11 (1), 269–277 (in Chinese with English abstract). Ludington, S., Plumlee, G.S., 2009. Climax-Type Porphyry Molybdenum Deposits, U.S. Geological Survey Open-file Report 2009–1215, 16 p. Ludwig, K.R., 2003. User's Manual for Isoplot 3.0: A Geochronological Toolkit for Microsoft Excel. Berkeley Geochron Center Special Publication, pp. 1–71. Meinert, L.D., Hedequist, J.W., Satoh, H., Matsuhisa, Y., 2003. Formation of anhydrous and hydrous skarn in Cu-Au ore deposits by magmatic fluids. Econ. Geol. 98, 147–156. Meng, S., Yan, C., Lai, Y., Shu, Q.H., Sun, Y., 2013. Study on the mineralization chronology and characteristics of mineralization fluid from the Chehugou porphyry Mo-Cu deposit, Inner Mongolia. Acta Petrol. Sin. 29 (1), 255–269 (in Chinese with English abstract). Ni, P., Wang, G.G., Yu, W., Chen, H., Jiang, L.L., Wang, B.H., Zhang, H.D., Xu, Y.F., 2015. Evidence of fluid inclusions for two stages of fluid boiling in the formation of the giant Shapinggou porphyry Mo deposit, Dabie Orogen, Central China. Ore Geol. Rev. 65, 1078–1094. Nie, F.J., Pei, R.F., Wu, L.S., Bjϕrlykke, A., 1994. Nd and Sr isotope study on metamorphosed volcanic rocks of the Bayanduxi Group, Inner Mongolia, China. Geol. Rev. 4 (5), 476–481 (in Chinese with English abstract). Nie, F.J., Jiang, S.H., Liu, Y.F., Bai, D.M., Tong, Y., 2016. Mesozoic Magmatism and Silver-polymetallic Mineralization in Mid-eastern of Inner Mongolia, First Edition. Geological Publishing House, Beijing (in Chinese). No. 6 GT (No. 6 Geological Team of Shandong Bureau of Geology and Mineral Resources), 2012. Exploration Report of the Bilugangan Mo Deposit, Abaga Banner, Inner Mongolia, China (in Chinese). Ohmoto, H., Rye, R.O., 1979. Isotopes of sulfur and carbon. In: Barnes, H.L. (Ed.), Geochemistry of Hydrothermal Ore Deposits, second ed. Wiley, New York, pp. 509–567. Ren, J.S., Chen, T.Y., Niu, B.G., Liu, Z.G., Liu, F.R., 1990. Tectonic Evolution of the Continental Lithosphere and Metallogeny in Eastern China and Adjacent Areas, First Edition. Science Press, Beijing (in Chinese). Robinson, B.W., Kusakabe, M., 1975. Quantitative preparation of sulfur dioxide, for 34S/ 32S analyses, from sulfides by combustion with cuprous oxide. Anal. Chem. 47 (7), 1179–1181. Seal II, R.R., 2006. Sulfur isotope geochemistry of sulfide minerals. Rev. Mineral. Geochem. 61, 633–677. Selby, D., Nesbitt, B.E., Muehlenbachs, K., Prochaska, W., 2000. Hydrothermal alteration and fluid chemistry of the Endako porphyry molybdenum deposit, British Columbia. Econ. Geol. 95, 183–202. Sengör, A.M.C., Natal’in, B.A., 1996. Palaeotectonics of Asia. Fragments of a Synthesis. In: Yin, A., Harrison, M. (Eds.), The Tectonic Evolution of Asia. Rubey Colloquium. Cambridge University Press, Cambridge, pp. 486–640. Sengör, A.M.C., Natal’in, B.A., Burtman, V.S., 1993. Evolution of the Altaid tectonic collage and Palaeozoic crustal growth in Eurasia. Nature 364, 299–307. Sillitoe, R.H., 1980. Types of porphyry molybdenum deposits. Min. Mag. 142 (6), 550–553. Smoliar, M.I., Walker, R.J., Morgan, J.W., 1996. Re-Os ages of group IIA, IIIA, IVA and VIB iron meteorites. Science 271, 1099–1102. Stein, H.J., Hannah, J.L., 1985. Movement and origin of ore fluids in Climax-type systems. Geology 13, 469–474. Sun, X., 2016. In: Geological, Geochemistry Characteristics and Genesis of Xishadegai Porphyry Type of Ore Deposit, Inner Mongolia. China University of Geosciences, Beijing, pp. 79 Master Thesis (in Chinese with English abstract). Sun, Y., Liu, J.M., Zeng, Q.D., Zhu, S.X., Zhou, L.L., Wu, G.B., Gao, Y.Y., Shen, W.J., 2013. Geological characteristics and molybdenite Re-Os ages of the Baituyingzi Mo-Cu field, eastern Inner Mongolia and their geological implications. Acta Petrol. Sin. 29 (1), 241–254 (in Chinese with English abstract). Tang, W.L., Zeng, W., Ran, H., Zhou, Y., Sun, W.L., Li, F.J., Yan, H.Q., 2012. Geological features and ore prospecting of the Bilugangan deposit, Abaga, Inner Mongolia. Geol. Survey Res. 35 (3), 161–166 (in Chinese with English abstract). Taylor Jr., H.P., 1974. The Application of oxygen and hydrogen isotope studies to

Audétat, A., Li, W., 2017. The genesis of Climax-type porphyry Mo deposits: insights from fluid inclusions and melt inclusions. Ore Geol. Rev. 88, 436–460. Cai, M.H., Peng, Z.A., Qu, W.J., He, Z.Y., Feng, G., Zhang, S.Q., Xu, M., Chen, Y., 2011a. Geological characteristics and Re-Os dating of molybdenites in Chagandeersi molybdenum deposit, western Inner Mongolia. Miner. Deposit 30, 377–384 (in Chinese with English abstract). Cai, M.H., Zhang, Z.G., Qu, W.J., Peng, Z.A., Zhang, S.Q., Xu, M., Chen, Y., Wang, X.B., 2011b. Geological characteristics and Re-Os dating of the Chaganhua molybdenum deposit in Urad Rear Banner, Western Inner Mongolia. Acta Geosci. Sin. 32, 64–68 (in Chinese with English abstract). Carten, R.B., White, W.H., Stein, H.J., 1993. High-Grade Granite-Related Molybdenum Systems: Classification and Origin. In: Kirkham, R.V., Sinclair, W.D., Thorpe, R.I., Duke, J.M. (Eds.), Mineral Deposit Modeling. Geological Association of Canada Special Paper 40, 521–554. Chen, Y.J., Zhai, M.G., Jiang, S.Y., 2009. Significant achievements and open issues in study of orogenesis and metallogenesis surrounding the North China continent. Acta Petrol. Sin. 25, 2695–2726 (in Chinese with English abstract). Chen, Y.J., Zhang, C., Li, N., Yang, Y.F., Deng, K., 2012. Geology of the Mo deposits in Northeast China. J. Jilin Univ. (Earth Sci. Ed.) 42, 1223–1268 in Chinese with English abstract. Chen, Y.J., Wang, P., Li, N., Yang, Y.F., Pirajno, F., 2017a. The collision-type porphyry Mo deposits in Dabie Shan, China. Ore Geol. Rev. 81, 405–430. Chen, Y.J., Zhang, C., Wang, P., Pirajno, F., Li, N., 2017b. The Mo deposits of Northeast China: a powerful indicator of tectonic settings and associated evolutionary trends. Ore Geol. Rev. 81, 602–640. Clayton, R.N., Mayeda, T.K., 1963. The use of bromine pentafluoride in the extraction of oxygen from oxides and silicates for isotopic analysis. Geochim. Cosmochim. Acta 27, 43–52. Clayton, R.N., O’Neil, J.R., Mayeda, T.K., 1972. Oxygen isotope exchange between quartz and water. J. Geophys. Res. 77, 3057–3067. Du, A.D., He, H.L., Yin, N.W., Zou, X.Q., Sun, Y.L., Sun, D.Z., Chen, S.Z., Qu, W.J., 1994. A study on the rhenium–osmium geochronometry of molybdenites. Acta Geol. Sin. 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., Malinovskiy, D., 2004. Preparation and certification of Re-Os dating reference materials: molybdenites HLP and JDC. Geostand. Geoanal. Res. 28, 41–52. Duan, X.X., Zeng, Q.D., Yang, Y.H., Liu, J.M., Chu, S.X., Sun, Y., Zhang, Z.L., 2015. Triassic magmatism and Mo mineralization in Northeast China: geochronological and isotopic constraints from the Laojiagou porphyry Mo deposit. Int. Geol. Rev. 57 (1), 55–75. Faure, M., Lin, W., Schärer, U., Shu, L., Sun, Y., Arnaud, N., 2003. Continental subduction and exhumation of UHP rocks. Structural and geochronological insights from the Dabieshan (E. China). Lithos 70, 213–241. Faure, M., Lin, W., Chu, Y., Lepvrier, C., 2016. Triassic tectonics of the southern margin of the South China Block. C.R. Geosci. 348 (1), 5–14. Feng, X.X., Yao, S.Z., Duan, M., Qu, K., Wang, J.Y., Feng, X.B., Li, C., Zhou, L.M., 2015. Re-Os Dating of Molybdenite from the Bainaimiao Cu (Mo)Deposit in Inner Mongolia and Its Geological Significance. J. Jilin Univ.: Earth Sci. Ed. 45 (1), 132–141 (in Chinese with English abstract). Guo, F., Fan, W.M., Gao, X.F., Li, C.W., Miao, L.C., Zhao, L., Li, H.X., 2010. Sr–Nd–Pb isotope mapping of Mesozoic igneous rocks in NE China: constraints on tectonic framework and Phanerozoic crustal growth. Lithos 120, 563–578. Han, G., Liu, Y., Neubauer, F., Johann, G., Zhao, Y., Wen, Q., Li, W., Wu, L., Jiang, X., Zhao, L., 2012. Provenance analysis of Permian sandstones in the central and southern Da Xing'an Mountains, China: constraints on the evolution of the eastern segment of the Central Asian Orogenic Belt. Tectonophysics 580, 100–113. Hoefs, J., 2009. Stable Isotope Geochemistry (sixth edition). Springer, Berlin, pp. 1–285. Jahn, B.M., Wu, F.Y., Chen, B., 2000. Massive granitoid generation in central Asia: Nd isotopic evidence and implication for continental growth in the Phanerozoic. Episodes 23, 82–92. Jiang, S.H., Liang, Q.L., Bagas, L., 2014. Re-Os ages for molybdenum mineralization in the Fengning region of northern Hebei Province, China: new constraints on the timing of mineralization and geodynamic setting. J. Asian Earth Sci. 79, 873–883. Jiang, S.H., Chen, C.L., Bagas, L., Liu, Y., Han, N., Kang, H., Wang, Z.H., 2017. Two mineralization events in the Baiyinnuoer Zn-Pb deposit in Inner Mongolia, China: evidence from field observations, S-Pb isotopic compositions and U-Pb zircon ages. J. Asian Earth Sci. 144, 339–367. Keith, J.D., Christiansen, E.H., Carten, R.B., 1993. The Genesis of Giant Porphyry Molybdenum Deposits. Soc Econ Geol Giant Ore Deposits Spec Publ, pp. 285–317. Kusky, T.M., Windley, B.F., Zhai, M.-G., 2007. Tectonic evolution of the North China Block: from orogen to craton to orogen. Geol. Soc., London, Special Publ. 280, 1–34. Li, J.Y., 2006. Permian geodynamic setting of Northeast China and adjacent regions: closure of the Paleo-Asian Ocean and subduction of the Paleo-Pacific Plate. J. Asian Earth Sci. 26, 207–224. Li, S.Z., Kusky, T.M., Wang, L., Zhang, G.W., Lai, S.C., Liu, X.C., Dong, S.W., Zhao, G.C., 2007. Collision leading to multiple-stage large-scale extrusion in the Qinling orogen: insights from the Mianlue suture. Gondwana Res. 12, 121–143. Li, Y., Li, X.H., Selby, D., Li, J.W., 2018. Pulsed magmatic fluid release for the formation of porphyry deposits: tracing fluid evolution in absolute time from the Tibetan Qulong Cu – Mo deposit. Geology 76 (1), 7–10. Li, S.J., Luan, X.W., Wang, L., 2016b. Evolution of ore fluids and metallogenic mechanism in Bilugangan molybdenum-copper deposit, Abaga Inner Mongolia. Acta Petrol. Sin. 32 (8), 2509–2521 (in Chinese with English abstract).

851

Ore Geology Reviews 107 (2019) 837–852

L. Zhang, et al.

Rundsch) 98, 1189–1217. Xiao, W.J., Windley, B.F., Sun, S., Li, J.L., Huang, B.C., Han, C.M., Yuan, C., Sun, M., Chen, H.L., 2015. A tale of amalgamation of three permo-triassic collage systems in Central Asia: oroclines, sutures, and terminal accretion. Annu Rev. Earth Planet Sci. 43, 477–507. Xu, B., Chen, B., Zhang, C., Bai, Z.Q., Wang, H.W., Zhang, Q., 1994. Sm-Nd isochron and significance of the Wuhuaoubao block in northern margin of Sino-Korean Plate. Sci. Geol. Sin. 29 (2), 168–172 (in Chinese with English abstract). Xu, B., Chen, B., Shao, J.A., 1996. A study on Sm-Nd and Rb-Sr isotopic chronology of the Xilingele complex, Inner Mongolia. China Sci. Bull. 41 (2), 153–155 (in Chinese). Xu, B., Zhao, P., Wang, Y., Liao, W., Luo, Z., Bao, Q., Zhou, Y., 2015. The pre-Devonian tectonic framework of Xing’an–Mongolia orogenic belt (XMOB) in north China. J. Asian Earth Sci. 97, 183–196. Yakubchuk, A., 2017. Evolution of the Central Asian Orogenic Supercollage since Late Neoproterozoic revised again. Gondwana Res. 47, 372–398. 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. Int. Geol. Rev. 54 (16), 1843–1869. Zeng, Q.D., Sun, Y., Duan, X.X., Liu, J.M., 2013. U-Pb and Re–Os geochronology of the Haolibao porphyry Mo–Cu deposit, NE China: implications for a Late Permian tectonic setting. Geol. Mag. 150, 975–985. Zhang, Y.M., Gu, X.X., Liu, R.P., Gao, H.J., Su, Y., Zheng, L., Gu, F.H., 2014. Geochronology of intrusive rocks and associated ores of the Gaogangshan Porphyry Molybdenum Deposit in Heilongjiang Province. Bull. Mineral., Petrol. Geochem. 33 (5), 624–635 (in Chinese with English abstract). Zhang, Y.F., Liang, S., 2017. Geochemistry of Ore-forming fluids and genesis of Chagandells molybdenum deposit in Inner Mongolia. North-western Geol. 50 (204), 106–114 (in Chinese with English abstract). Zheng, Y.F., Zhang, L.F., McClelland, W.C., Cuthbert, S., 2012. Processes in continental collision zones: preface. Lithos 136–139, 1–9. Zhou, J.B., Wilde, S.A., 2013. The crustal accretion history and tectonic evolution of the NE China segment of the Central Asian Orogenic Belt. Gondwana Res. 23, 1365–1377.

problems of hydrothermal, alteration and ore deposition. Econ. Geol. 69, 843–883. Taylor, B.E., Eichelberger, J.C., Westrich, H.R., 1983. Hydrogen isotopic evidence of rhyolitic magma degassing during shallow intrusion and eruption. Nature 306, 541–545. U.S. Geological Survey, 2016. Mineral commodity summaries 2016. U.S. Geological Survey, 202 p. Wan, D.F., Fan, T.Y., Tian, S.H., 2005. The chromium analytical technique for hydrogen isotopes. Acta Geosci. Sin. 26, 35–38 (in Chinese with English abstract). Wang, P., Wang, Y., Yang, Y.F., 2017. Zircon U-Pb geochronology and isotopic geochemistry of the Tangjiaping Mo deposit, Dabie Shan, China: implications for ore genesis and tectonic setting. Ore Geol. Rev. 81, 466–483. Wareham, C.D., Rice, C.M., 1998. S, C, Sr, and Pb sources in the Pliocene Silver Creek Porphyry Mo ystem, Rico, Colorado. Econ. Geol. 93, 32–46. White, W.H., Bookstrom, A.A., Kamilli, R.J., Ganster, M.W., Smith, R.P., Ranta, D.E., Steininger, R.C., 1981. Character and origin of climax-type molybdenum deposits. Econ. Geol. 270–316. Wu, H., 2015. Ore-forming fluid study of the Dasuji porphyry molybdenum deposit in Zhuozi County, Inner Mongolia. China University of Geosciences, Beijing Master’s Thesis (in Chinese with English abstract). Wu, F.Y., Sun, D.Y., Ge, W.C., Zhang, Y.B., Grant, M.L., Wilde, S.A., Jahn, B.M., 2011. Geochronology of the Phanerozoic granitoids in northeastern China. J. Asian Earth Sci. 41, 1–30. Wu, Y.B., Zheng, Y.F., 2013. Tectonic evolution of a composite collision orogen: an overview on the Qinling–Tongbai–Hong'an–Dabie–Sulu orogenic belt in central China. Gondwana Res. 23, 1402–1428. Xiang, A.P., Yang, Y.C., Li, G.T., She, H.Q., Guan, J.D., Li, J.W., Guo, Z.J., 2012. Diagenetic and metallogenic ages of Duobaoshan porphyry Cu-Mo deposit in Heilongjiang Province. Miner. Deposits 31, 1237–1248 (in Chinese with English abstract). Xiao, W.J., Windley, B.F., Huang, B.C., Han, C.M., Yuan, C., Chen, H.L., Sun, M., Sun, S., Li, J.L., 2009. End-Permian to mid-Triassic termination of the accretionary processes of the southern Altaids: Implications for the geodynamic evolution, Phanerozoic continental growth, and metallogeny of Central Asia. Int. J. Earth Sci. (Geol.

852