Major and Trace Element Geochemistry of Pyrite and Pyrrhotite from Stratiform and Lamellar Orebodies: Implications for the Ore Genesis of the Dongguashan Copper (Gold) Deposit, Eastern China

The Dongguashan copper (gold) deposit in Anhui Province is one of the largest copper (gold) deposits in the Tongling ore district, which is the most important region in the Middle–Lower Yangtze River Metallogenic Belt, Eastern China. Stratiform and lamellar orebodies are the major deposit types. Pyrite and pyrrhotite from the stratiform deposit type (Py I, Po I) and lamellar deposit type (Py II, Po II) are investigated using Electron-probe Microanalyses (EPMA) and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). Py I, Py II, Po I and Po II have high contents of Cu, Co, Au and Se, low contents of As, Pb and Zn, with Co/Ni ratios of 0.50−48.00, 4.00−45.00, 1.55−14.45 and 1.02−1.36, respectively, most of which are greater than 1 and vary widely; these characteristics are consistent with those of pyrite with a magmatic–hydrothermal origin. The higher Au/Ag and Fe/(S + As) ratios of pyrite and crystallization temperatures (286–387 ◦C) of hexagonal pyrrhotite indicate that the mineralization occurrs in environments with mediumto high-temperatures, high sulfur fugacity and medium-shallow depths. Therefore, we suggest that the Dongguashan copper (gold) deposit is a stratabound skarn-type ore deposit associated with magma intrusion activity during the Yanshanian Period.


Introduction
As minerals represent the most basic units of rocks and/or ore, their chemical composition and type are of great significance when discussing the origins of rocks and/or ore, as well as the ore genesis and the ore-forming environment [1,2]. Due to the influence of factors, such as the purity of single minerals and the interference associated with solid solutions, the data obtained using traditional chemical analyses for single phases have large errors. The rapid development of Electron-Probe Microanalyses (EPMA) and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) has realized in situ analysis of single minerals at the nanoscale, which has The Dongguashan copper (gold) ore deposit is one of the largest copper (gold) deposits in the Tongling ore district, and it is located approximately 7 km to the east of Tongling city (Figure 2), Anhui Province, Eastern China. It is controlled by stratigraphic horizons, anticlines, and interlayered structures. The major stratiform and lamellar orebodies in the Dongguashan deposit are distributed along the northern core and limbs of the Qingshan anticline, and they are hosted in the limestones of the Middle and Upper Carboniferous Huanglong and Chuanshan formations. The Dongguashan copper (gold) deposit, with its unique geological characteristics, has attracted a lot of attention to geologists for a long time. A great deal of scientific progress has been made in identifying the source of ore-forming materials and fluids, rock-and ore-forming ages, and ore genesis [17][18][19][20][21][22][23][24][25][26]. However, as far as the ore genesis of the Dongguashan copper (gold) deposit is concerned, questions remain, as this deposit has been proposed to be a stratabound skarn-type [15,23,25,[27][28][29], exhalative sedimentary and hydrothermal superimposition-type [21,22,[30][31][32][33][34][35][36], and exhalative sedimentary-type deposit [19,[37][38][39]. The Dongguashan copper (gold) ore deposit is one of the largest copper (gold) deposits in the Tongling ore district, and it is located approximately 7 km to the east of Tongling city (Figure 2), Anhui Province, Eastern China. It is controlled by stratigraphic horizons, anticlines, and interlayered structures. The major stratiform and lamellar orebodies in the Dongguashan deposit are distributed along the northern core and limbs of the Qingshan anticline, and they are hosted in the limestones of the Middle and Upper Carboniferous Huanglong and Chuanshan formations. The Dongguashan copper (gold) deposit, with its unique geological characteristics, has attracted a lot of attention to geologists for a long time. A great deal of scientific progress has been made in identifying the source of ore-forming materials and fluids, rock-and ore-forming ages, and ore genesis [17][18][19][20][21][22][23][24][25][26]. However, as far as the ore genesis of the Dongguashan copper (gold) deposit is concerned, questions remain, as this deposit has been proposed to be a stratabound skarn-type [15,23,25,[27][28][29], exhalative sedimentary and hydrothermal superimposition-type [21,22,[30][31][32][33][34][35][36], and exhalative sedimentary-type deposit [19,[37][38][39]. Questions regarding deposit genesis is mainly focused on stratiform and lamellar orebodies. It will be helpful for us to understand the ore genesis by determining their geneses. In this paper, we are going to study the major and trace element compositions of pyrite and pyrrhotite in stratiform and lamellar orebodies by using EPMA and LA-ICP-MS and to constrain the ore genesis.

Geological Setting
The Tongling ore district is located in the northeastern section of the Lower Yangtze area, in the junction between North China and the Yangtze Block. This ore district is bounded by the Xiangfan-Guangji fault to the north, the Tanlu fault to the northeast, and the Yangxing-Changzhou fault to the south ( Figure 1). A three-stage tectonic evolution of the Lower Yangtze area has been proposed, i.e., the formation of Pre-Sinian (Late Neoproterozoic) basement, the development of Sinian to Early Triassic sedimentary cover, and intraplate deformation from the Middle Triassic to the Cenozoic [41][42][43]. The EW-trending basement faults, NE-and NNE-trending folds and associated interformational fracture zones are the major structures. The outcropping strata mainly consist of Silurian to Triassic neritic-and littoral-facies sedimentary carbonate rocks [44]. Yanshanian intermediate-acid intrusive rocks are widely distributed in this area [45], and their rock-forming ages dated from 135 Ma to 147 Ma [46]. The mineralization is dominated by copper, iron, gold, lead and zinc, showing an east-west trending zonation ranging from lead to zinc rich in the north and south and from copper to gold rich in the middle.
The Dongguashan copper (gold) ore deposit is situated at the intersection of the EW-trending Tongling-Shatanjiao tectonic-magmatic belt and the Qingshan anticline of the NE-trending Shun'an synclinorium [23,47] (Figures 2 and 3). The mineralization is mainly related to the siliceous and argillaceous hornfels of the Upper Devonian Wutong Formation, impure carbonate of the Middle to Upper Carboniferous Chuanshan and Huanglong formations, and bioclastic limestone and skarn of the Lower Permian Qixia Formation. There are NE-trending folds and SN-, EW-and NNE-trending faults in the Dongguashan deposit. The NE-trending Qingshan anticline and the associated interformational fracture zones between the Carboniferous and Devonian strata are the most Questions regarding deposit genesis is mainly focused on stratiform and lamellar orebodies. It will be helpful for us to understand the ore genesis by determining their geneses. In this paper, we are going to study the major and trace element compositions of pyrite and pyrrhotite in stratiform and lamellar orebodies by using EPMA and LA-ICP-MS and to constrain the ore genesis.

Geological Setting
The Tongling ore district is located in the northeastern section of the Lower Yangtze area, in the junction between North China and the Yangtze Block. This ore district is bounded by the Xiangfan-Guangji fault to the north, the Tanlu fault to the northeast, and the Yangxing-Changzhou fault to the south ( Figure 1). A three-stage tectonic evolution of the Lower Yangtze area has been proposed, i.e., the formation of Pre-Sinian (Late Neoproterozoic) basement, the development of Sinian to Early Triassic sedimentary cover, and intraplate deformation from the Middle Triassic to the Cenozoic [41][42][43]. The EW-trending basement faults, NE-and NNE-trending folds and associated interformational fracture zones are the major structures. The outcropping strata mainly consist of Silurian to Triassic neritic-and littoral-facies sedimentary carbonate rocks [44]. Yanshanian intermediate-acid intrusive rocks are widely distributed in this area [45], and their rock-forming ages dated from 135 Ma to 147 Ma [46]. The mineralization is dominated by copper, iron, gold, lead and zinc, showing an east-west trending zonation ranging from lead to zinc rich in the north and south and from copper to gold rich in the middle.
The Dongguashan copper (gold) ore deposit is situated at the intersection of the EW-trending Tongling-Shatanjiao tectonic-magmatic belt and the Qingshan anticline of the NE-trending Shun'an synclinorium [23,47] (Figures 2 and 3). The mineralization is mainly related to the siliceous and argillaceous hornfels of the Upper Devonian Wutong Formation, impure carbonate of the Middle to Upper Carboniferous Chuanshan and Huanglong formations, and bioclastic limestone and skarn of the Lower Permian Qixia Formation. There are NE-trending folds and SN-, EW-and NNE-trending faults in the Dongguashan deposit. The NE-trending Qingshan anticline and the associated interformational fracture zones between the Carboniferous and Devonian strata are the most important ore-controlling structures in this area. The complex structure network in this area provides channels for the ascent and emplacement of magma during the Yanshanian period. The Qingshanjiao quartz monzodiorite is closely related to the mineralization in the Dongguashan deposit [29]. important ore-controlling structures in this area. The complex structure network in this area provides channels for the ascent and emplacement of magma during the Yanshanian period. The Qingshanjiao quartz monzodiorite is closely related to the mineralization in the Dongguashan deposit [29]. The types of orebodies in the Dongguashan deposit include stratiform, lamellar, porphyry and vein-like orebodies. The stratiform orebody is the major orebody, which is distributed along the northern core and limbs of the Qingshan anticline and hosted in the limestones of the Middle and Upper Carboniferous Huanglong and Chuanshan formations. It is NE-striking and generally tends to plunge to the northeast, and it is in concordance with the occurrence of the surrounding rocks. The major stratiform orebody is controlled by the strata, interlayered structures, and contact zones between the Qingshanjiao pluton and its wall rocks. The metal minerals in the major orebody are mainly magnetite, pyrrhotite, pyrite and chalcopyrite, with minor bornite, chalcocite, sphalerite, tetrahedrite, molybdenite, galena, and native gold. The gangue minerals include quartz, calcite, garnet, diopside, and epidote, with minor actinolite, tremolite and anhydrite. A thin lamellar orebody is developed at the bottom of the stratiform orebody, which consists of serpentine, tremolite, talc, pyrite, pyrrhotite and chalcopyrite. The vein-like or veinlet-disseminated orebodies are mainly distributed in the upper part of the Qingshanjiao pluton and close to its wall rocks. The porphyry-type orebody is mainly developed inside the Qingshanjiao pluton and contains chalcopyrite, pyrite, potash feldspar, plagioclase and quartz. Based on their ore fabric characteristics and spatial output locations, the ore types can be classified as massive, vein-like, lamellar, and disseminated ores. The ores have massive, lamellar, vein-like and disseminated structures and granular, metasomatic and exsolution textures ( Figure 4). The wall rock alteration of the Dongguashan copper (gold) deposit is well developed, as is evident by the presence of altered minerals, including garnet, diopside, forsterite, quartz, K-feldspar, sericite, serpentine, calcite, The types of orebodies in the Dongguashan deposit include stratiform, lamellar, porphyry and vein-like orebodies. The stratiform orebody is the major orebody, which is distributed along the northern core and limbs of the Qingshan anticline and hosted in the limestones of the Middle and Upper Carboniferous Huanglong and Chuanshan formations. It is NE-striking and generally tends to plunge to the northeast, and it is in concordance with the occurrence of the surrounding rocks. The major stratiform orebody is controlled by the strata, interlayered structures, and contact zones between the Qingshanjiao pluton and its wall rocks. The metal minerals in the major orebody are mainly magnetite, pyrrhotite, pyrite and chalcopyrite, with minor bornite, chalcocite, sphalerite, tetrahedrite, molybdenite, galena, and native gold. The gangue minerals include quartz, calcite, garnet, diopside, and epidote, with minor actinolite, tremolite and anhydrite. A thin lamellar orebody is developed at the bottom of the stratiform orebody, which consists of serpentine, tremolite, talc, pyrite, pyrrhotite and chalcopyrite. The vein-like or veinlet-disseminated orebodies are mainly distributed in the upper part of the Qingshanjiao pluton and close to its wall rocks. The porphyry-type orebody is mainly developed inside the Qingshanjiao pluton and contains chalcopyrite, pyrite, potash feldspar, plagioclase and quartz. Based on their ore fabric characteristics and spatial output locations, the ore types can be classified as massive, vein-like, lamellar, and disseminated ores. The ores have massive, lamellar, vein-like and disseminated structures and granular, metasomatic and exsolution textures ( Figure 4). The wall rock alteration of the Dongguashan copper (gold) deposit is well developed, as is evident by the presence of altered minerals, including garnet, diopside, forsterite, quartz, K-feldspar, sericite, serpentine, calcite, hornfels and chlorite, with minor anhydrite and talc. The enrichment of metal minerals is closely related to the skarnization, silicification and retrograde alteration of early skarn. hornfels and chlorite, with minor anhydrite and talc. The enrichment of metal minerals is closely related to the skarnization, silicification and retrograde alteration of early skarn. Based on field investigations and microscopic observations of mineralogy and mineral associations, the mineralization can be divided into three skarn development stages: the skarn stage, retrograde-altered stage and quartz-carbonate stage. The skarn stage is composed of garnet, diopside and humite. The retrograde-altered stage, which is the main mineralization stage, predominantly contains chalcopyrite, pyrite, magnetite, pyrrhotite, sphalerite, chalcocite, serpentine, epidote, quartz and talc. The quartz-carbonate stage is mainly characterized by the veil-like output of late quartz and calcite, accompanied by a small amount of metal sulfides.

Electron-Probe Microanalyses
The pyrite (Py I) samples used for EPMA were collected from the massive ores of the stratiform orebody (sample DGS1  Based on field investigations and microscopic observations of mineralogy and mineral associations, the mineralization can be divided into three skarn development stages: the skarn stage, retrograde-altered stage and quartz-carbonate stage. The skarn stage is composed of garnet, diopside and humite. The retrograde-altered stage, which is the main mineralization stage, predominantly contains chalcopyrite, pyrite, magnetite, pyrrhotite, sphalerite, chalcocite, serpentine, epidote, quartz and talc. The quartz-carbonate stage is mainly characterized by the veil-like output of late quartz and calcite, accompanied by a small amount of metal sulfides.

Electron-Probe Microanalyses
The pyrite (Py I) samples used for EPMA were collected from the massive ores of the stratiform orebody (sample DGS1  [48]. All data were corrected using a standard ZAF routine. The minimum detection limits of the elements are ≤0.01 wt.%.

Laser Ablation Inductively Coupled Plasma Mass Spectrometry Trace Element Analysis
This analysis was completed at Akita University in Japan. The microelement analysis instrument was an Agilent 7500i quadrupole ICP-MS mass spectrometer, employing a New Wave Research 5906 system. The laser beam frequency was 6 Hz, the energy was 850 MJ, and the analysis point size was 45 µm. At each analysis point, the data collection included 30 s of gas background value measurement, 30 s of a mass spectrometry standard sample ablation, and 30 s of sample ablation. The minimum detection limits of the elements were ≤0.01 ppm.     Figure 6). The Py II samples from lamellar ores have higher Cu and Mn contents compared to the Py I samples from massive ores.      Figure 6). The Py II samples from lamellar ores have higher Cu and Mn contents compared to the Py I samples from massive ores.    1.19, respectively. The Po I samples from the massive ore has higher Cu contents compared to the Po II samples from the lamellar ore.

Implications for Ore-Forming Environment
The Fe atomic percent values of hexagonal pyrrhotite and monoclinic pyrrhotite are 47.0-47.8 at.% and 46.5-47.0 at.%, respectively [49]. These data indicate that the pyrrhotite in the Dongguashan deposit mainly contains hexagonal and monoclinic pyrrhotite. The Fe atomic percent and content of pyrrhotite reach up to 48.35 at.% and 60.64 wt.% in the sample DGS 5-9 (collected in the stratiform orebody), respectively, which is similar to the composition of pyrrhotite in the corresponding mantle inclusion [50]. Using the T-x (Fe) imitative straight-line equation of y = −201.22x + 9854.32 (y is the temperature, x is the Fe atomic percent [51]), the crystallization temperatures of monoclinic pyrrhotite were calculated. The results show that the crystallization temperatures of monoclinic pyrrhotite range from 286 to 387 • C, with an average value of 353 • C, indicating that different pyrrhotites formed in a medium-to high-temperature environment. In general, the Co contents of high-temperature pyrite, medium-temperature pyrite and low-temperature pyrite are >1000 ppm, 100-1000 ppm and <100 ppm, respectively [52]. The larger value of the Co/Ni implies the higher temperature of pyrite formation [53]. The Co contents of Py I and Py II are 0.009-0.96 wt.% (90-9600 ppm) and 0.02-0.45 wt.% (200-4500 ppm), with corresponding average values of 0.21 wt.% (2100 ppm) and 0.16 wt.% (1600 ppm), respectively (Appendix A). This supports the conclusions that Py I and Py II were formed in mediumand high-temperature environments. Arsenic can replace S isomorphically in pyrite, and As tends to be enriched in low-temperature systems [2]. Most of the As contents of Py I and Py II are below the detection limit, indicating that the ore-forming system is a high-temperature system. Moreover, Py I and Py II have high Au/Ag ratios (most >1, Figure 7a, Appendix A), which are different from those of sedimentary/diagenetic pyrite [6,54], reflecting that the Dongguashan copper (gold) deposit has a medium-to high-temperature hydrothermal genesis [55]. Py I and Py II are depleted in Ni, As, Pb, Te and Sb, which are different from those of synsedimentary pyrite [56], according to the geochemical characteristics of the high temperature hydrothermal pyrite [2]. The higher contents of Mn, Cu, Se and Zn show some similarity with the skarn deposit [57].
As mentioned above, different pyrites and pyrrhotites are formed in medium-to high-temperature environments, which is supported by the temperature measurement results of fluid inclusions in the same mineralization stage (retrograde-altered stage) (fluid inclusion temperature: 220-450 • C, average: 325.6 • C [24]).
The Fe/(S + As) ratio values of pyrite exhibit good correlation with their formation depth; the ratios of deep formation environments, medium-depth environments and shallow environments are 0.846, 0.863 and 0.926, respectively [56]. The Fe/(S + As) ratio values of Py I and Py II in the Dongguashan copper (gold) deposit range from 0.84 to 0.93 and from 0.87 to 0.94, with corresponding average values of 0.89 and 0.89, respectively (Appendix A). These data show that the formation environment of pyrite and pyrrhotite is an epithermal environment.
The presence of abundant pyrite indicates that there is sufficient sulfur. Pyrrhotite is mainly monoclinic pyrrhotite, with a small amount of hexagonal pyrrhotite, which indicates that it experienced a rapid cooling process and higher sulfur fugacity [58]. As mentioned above, the Dongguashan deposit formed in a medium-high temperature, high sulfur fugacity and epithermal environment.

Source of Ore-Forming Materials
The source of ore-forming materials of the Dongguashan copper (gold) deposit has not yet been well constrained. Based on the S and Pb isotope analyses, Xu [23,59] proposed that the ore-forming materials mainly originate from magma. Xu [18] considered that the underlying Paleozoic strata are an important metallogenic metal source area. Hou [35] and Cao [26] suggested that the ore-forming materials are derived from both sedimentary strata and magma. Lu [60] considered that the ore-forming materials are derived from a Hercynian submarine exhalative event. However, Liu [25] suggested that in the Qingshanjiao pluton, Py I and Py II have similar S and Pb isotopic compositions, and thus that Yanshanian magmatic activity plays a key role in copper (gold) mineralization. The in situ trace element analyses of single pyrite and pyrrhotite grains more effectively constrain the source of the ore-forming materials. Most pyrite crystals show low Bi contents (<1 ppm, Appendix C, Figure 7b). High Zn, Cd and Bi contents in pyrite probably indicate a sedimentary source [61]. In Figure 7b, most of Bi contents are less than 1 ppm, suggesting that there is no sediment influence for pyrite. Magmatic volatiles possibly cause the high Bi contents (>1 ppm) of very few points [61]. Therefore, the source of ore-forming materials of the Dongguashan copper (gold) deposit is not a sedimentary source.  Figure 7b). High Zn, Cd and Bi contents in pyrite probably indicate a sedimentary source [61]. In Figure 7b, most of Bi contents are less than 1 ppm, suggesting that there is no sediment influence for pyrite. Magmatic volatiles possibly cause the high Bi contents (>1 ppm) of very few points [61]. Therefore, the source of ore-forming materials of the Dongguashan copper (gold) deposit is not a sedimentary source. The high Au contents in pyrite and pyrrhotite suggest that Au may originate from magma [62,63]. The Cu contents of Py I, Py II, Po I and Po II are 0.04-461.81 ppm, 1.02-1311.82 ppm, 6.3-15,806.7 ppm and 29.0-3576.9 ppm, with corresponding average values of 79. 65 ppm, 191.86 ppm, 3961.38 ppm and 1802.97 ppm, respectively (Appendixes C and D), which are far higher than that obtained by Vinogradov (47 ppm,Vinogradov [64]). In addition, Py I, Py II, Po I and Po II have high Au and low Pb and Zn contents (Appendixes C and D), which supports the inference that the ore-forming materials may have been mainly derived from magma that contains abundant Cu and Au. This is consistent with the lack of galena and sphalerite in this area. As mentioned above, the source of ore-forming metals may have been sourced from mantle-derived magma.

Implications for Ore Genesis
In general, hydrothermal pyrite is depleted in sulfur, and sedimentary pyrite is rich in sulfur or close to its theoretical value [65]. The S/Fe atomic ratio values of Py I and Py II in the Dongguashan deposit are 1.87-2.05 and 1.85-2.00, with corresponding average values of 1.97 and 1.95 (Appendix A), respectively, thus showing sulfur-deficient characteristics [66][67][68]. This observation suggests that both Py I and Py II are hydrothermal-origin pyrite. The Co and Ni contents in pyrite and pyrrhotite can reflect the origin of pyrite, as well as its ore genesis and geological setting [69][70][71] 50 and 0.20-20.33, respectively. The Sb/Au atomic ratios of Py I and Py II are 0.07-6.14 and 0.08-0.67, respectively (Appendix A). As/Au and Sb/Au atomic ratios are less than those of sedimentary pyrite The high Au contents in pyrite and pyrrhotite suggest that Au may originate from magma [62,63]. The Cu contents of Py I, Py II, Po I and Po II are 0.04-461.81 ppm, 1.02-1311.82 ppm, 6.3-15,806.7 ppm and 29.0-3576.9 ppm, with corresponding average values of 79. 65 ppm, 191.86 ppm, 3961.38 ppm and 1802.97 ppm, respectively (Appendixs C and D), which are far higher than that obtained by Vinogradov (47 ppm,Vinogradov [64]). In addition, Py I, Py II, Po I and Po II have high Au and low Pb and Zn contents (Appendixs C and D), which supports the inference that the ore-forming materials may have been mainly derived from magma that contains abundant Cu and Au. This is consistent with the lack of galena and sphalerite in this area. As mentioned above, the source of ore-forming metals may have been sourced from mantle-derived magma.

Implications for Ore Genesis
In general, hydrothermal pyrite is depleted in sulfur, and sedimentary pyrite is rich in sulfur or close to its theoretical value [65]. The S/Fe atomic ratio values of Py I and Py II in the Dongguashan deposit are 1.87-2.05 and 1.85-2.00, with corresponding average values of 1.97 and 1.95 (Appendix A), respectively, thus showing sulfur-deficient characteristics [66][67][68]. This observation suggests that both Py I and Py II are hydrothermal-origin pyrite. The Co and Ni contents in pyrite and pyrrhotite can reflect the origin of pyrite, as well as its ore genesis and geological setting [69][70][71]. The Co/Ni ratios of sedimentary pyrite and magmatic-hydrothermal pyrite have values of Co/Ni < 1 and Co/Ni > 1, respectively [1,65,69,72]. The Co/Ni ratios of Py I, Py II, Po I and Po II are 0.50-48.00, 4.00-45.00, 1.55-14.45 and 1.02-1.36, respectively (Appendix A). The As/Au ratios of Py I and Py II are 0.13-20.50 and 0.20-20.33, respectively. The Sb/Au ratios of Py I and Py II are 0.07-6.14 and 0.08-0.67, respectively (Appendix A). As/Au and Sb/Au ratios are less than those of sedimentary pyrite (As/Au > 200, Sb/Au > 100, [54,73]). Most of the Co/Ni ratios are greater than 1 and vary widely, which are consistent with the characteristics of pyrite with a magmatic-hydrothermal origin [74].
The Se contents of Py I and Py II in the Dongguashan deposit are 3.49-75.77 ppm and 7.83-87.40 ppm, with corresponding average values of 41.80 ppm and 34.56 ppm, respectively. These are greater than that of sedimentary pyrite (0.5-2 ppm), but they are similar to the Se contents (>20 ppm) of magmatic-hydrothermal-origin pyrite (Appendix C) [65]. Thus, it can be seen that Py I and Py II are magmatic-hydrothermal origins in this area. Large [6] studied the contents of trace elements in pyrites of different origins and used the changes in their Ni-Au contents to discriminate between pyrites formed by diagenesis and/or hydrothermal processes. In the Ni vs. Au discrimination diagram (Figure 8a), the samples of Py I and Py II fall within the field of hydrothermal pyrite. In the Zn vs. Pb discrimination diagram (Figure 8b), the samples of Py I and Py II fall within and near the field of hydrothermal pyrite. In the Co vs. Ni discrimination diagram (Figure 9), the samples of Py I and Py II mainly fall within the field of magmatic, and hydrothermal pyrite partially fall within the field of sedimentary pyrite, which may be related to the mixing of crustal materials. The samples of Po I and Po II fall near the deposit related to magmatic-hydrothermal solutions. Overall, the elemental contents indicate that Py I, Py II, Po I and Po II are magmatic-hydrothermal genesis.  In general, the trace element compositions of pyrite and pyrrhotite hosted in the stratiform and lamellar orebodies show that mineralization is closely related to magmatic-hydrothermal activities. Magmatic-hydrothermal fluid fills along the interformational fracture zones and comes in contact with the surrounding rock to generate chalcopyrite, magnetite, pyrite, pyrrhotite, garnet, diopside and epidote, which forms the stratiform orebody. The retrograde alteration of magnesian skarn minerals forms serpentine, talc, chalcopyrite, pyrite and pyrrhotite, and later forms the lamellar orebody by the self-organized developed of minerals [28]. In general, the trace element compositions of pyrite and pyrrhotite hosted in the stratiform and lamellar orebodies show that mineralization is closely related to magmatic-hydrothermal activities. Magmatic-hydrothermal fluid fills along the interformational fracture zones and comes in contact with the surrounding rock to generate chalcopyrite, magnetite, pyrite, pyrrhotite, garnet, diopside and epidote, which forms the stratiform orebody. The retrograde alteration of magnesian skarn minerals forms serpentine, talc, chalcopyrite, pyrite and pyrrhotite, and later forms the lamellar orebody by the self-organized developed of minerals [28]. lamellar orebodies show that mineralization is closely related to magmatic-hydrothermal activities. Magmatic-hydrothermal fluid fills along the interformational fracture zones and comes in contact with the surrounding rock to generate chalcopyrite, magnetite, pyrite, pyrrhotite, garnet, diopside and epidote, which forms the stratiform orebody. The retrograde alteration of magnesian skarn minerals forms serpentine, talc, chalcopyrite, pyrite and pyrrhotite, and later forms the lamellar orebody by the self-organized developed of minerals [28].

Conclusions
The major and trace element compositions indicate that the ore-forming materials are principally originated from the magmatism. Pyrite and pyrrhotite hosted in the stratiform and lamellar orebodies are magmatic-hydrothermal origins. The ore-forming conditions are medium-high temperature, high sulfur fugacity and medium-shallow depth. Therefore, the Dongguashan copper (gold) deposit should be a stratabound skarn-type ore deposit associated with magma intrusion activity during the Yanshanian Period. We are grateful to anonymous reviewers for their critical and constructive reviews, which greatly improved the paper.

Conflicts of Interest:
The authors declare no conflicts of interest. "-" below detection limits.