Zircon LA-ICP-MS U-Pb Ages and the Hf Isotopic Composition of the Ore-Bearing Porphyry from the Yanghuidongzi Copper Deposit, Heilongjiang, China, and Its Geological Signiﬁcance

: The Yanghuidongzi copper deposit is a typical porphyry copper deposit located at the eastern margin of the Xing’anling-Mongolian Orogenic Belt (XMOB). While much attention have been paid to the ore-forming age of the deposit and the magma source of the ore-bearing porphyry, this paper approaches this issue with the methods of the LA-ICP-MS zircon U-Pb dating and Lu-Hf isotopic composition of the Yanghuidongzi porphyry copper deposit. The results reveal that the Yanghuidongzi porphyry copper deposit was formed in the Early Jurassic (189.6 ± 1.0 Ma), which corresponds to the time of magmatic activity in this region. The background studies of ore-forming dynamics indicate that the formation of the Yanghuidongzi copper deposit is related to the subduction of the Paleo-Paciﬁc plate. The Yanghuidongzi ore-bearing porphyry zircons have a positive ε Hf ( t ) value (4.4–7.0), a high 176 Hf / 177 Hf ratio (0.282786–0.282854), and a two-stage Hf model ages ( T DM2 ) ranging from 783 Ma to 943 Ma, all of which suggest that the Early Jurassic granodiorite porphyry of the Yanghuidongzi deposit was formed by the partial melting of newly grown crustal material from the depleted mantle in the Neoproterozoic.


Introduction
Porphyry deposits are mainly formed at the boundary of converging plates, including island arcs [1][2][3][4][5], continental margin arcs [4,[6][7][8], and continental collision environments [9][10][11][12][13]. Thus, porphyry deposits are important geological markers for discussing regional tectonic evolution and tectonic settings [14]. The U-Pb isotopic system in natural zircon has a closure temperature greater than 900 • C [15,16], so zircons are regarded as ideal minerals for determining the age of magma crystallization [17]. Furthermore, zircons have a high Hf concentration (0.5-2%) and can maintain their original Hf isotopic composition even in the case of granulite facies, which could record the information of the magma source and magmatic activity [18][19][20].  [23] and (b) regional geological map of the Yanghuidongzi area [24,25] The strata in the area primarily comprise the lower Permian Pingyangzhen Formation (P 1 p), the lower Permian Shuangqiaozi Formation (P 1 s), the Triassic Luoquanzhan Formation (T 3 l), the Neogene Chuandishan Formation (βN 2 c), and the Holocene (Qh) (Figure 1b). The magmatism in the area is intense, and intermediate-acid intrusive rocks of the Middle-Late Triassic, Early Jurassic, and Early Cretaceous are widely developed (Figure 1b). The Dunhua-Mishan deep fault (F2) of the Mesozoic is closely related to the magmatism, and the NW-NE trending faults have established the structure pattern of the study area (Figure 1b).

Deposit Geology
The Lower Permian Shuangqiaozi Formation (P 1 s) is widely exposed in the mining area ( Figure 2a). This unit consists of a set of low-grade metamorphic rocks, including carbonaceous sericite phyllite, biotite quartz schist, and albite feldspar schist. The carbonaceous sericite phyllite are characterized by fine-grained granular crystalloblastic texture and phyllitic structure, mainly consist of quartz and sericite, with a small amount of biotite, chlorite, garnet, feldspar and opaque minerals. The biotite quartz schists are distributed in district 2 and district 3, have granular crystalloblastic structure, laminated crystalloblastic texture and schistose structure. The dominate mineral is quartz, and the secondary minerals are biotite, sericite, plagioclase and chlorite. The albite feldspar schists are distributed in district 2 and interbedded with biotite quartz schists, which are mainly composed of actinolite, and following are albite, calcite, biotite, and quartz, with fine-grained columnar crystalloblastic texture and schistose structure. Folds and faults in the mining area are relatively developed. The Yanwangdian anticline runs through the whole area, with an axial strike of NE 55 • , dipping to NW and SE (Figure 1b). During the structural extrusion process, the fracture zone generated in the anticline shaft provides a good enrichment site for ore filling. The faults are divided into two stages: pre-mineralization and post-mineralization. The pre-mineralization faults are SN trending (F1, F2, F3) and oblique to the anticline of the Yanwangdian anticline. Their intersection controls the location of the ore-bearing rock mass. The post-mineralization faults are NW and NWW trending (F4-F8), which causes the rock mass to become misaligned.
The intrusive rocks in the mining area are dominated by granodiorite (γδT 3 J 1 ), granodiorite porphyry (γδπT 3 J 1 ), and mica-plagioclase lamprophyre (χξχ). The granodiorite is mostly distributed in district 2 and district 3 (Figure 2a), while the granodiorite porphyry closely related to the mineralization is distributed only in district 1 (Figure 2a). The ore-bearing porphyry carried a large number of volatile components during the intrusion process, and great pressure was formed at the contact zone between the magma and the surrounding rock, and the surrounding rock of the contact zone was strongly broken to form breccia. Then, the breccia was filled and cemented by the ore-bearing hydrothermal fluid [21]. The breccia is mainly composed of sericite phyllite, granodiorite porphyry, and quartz vein and is mainly distributed in the contact between the granodiorite porphyry and surrounding rocks ( Figure 2b).

Sample Collection and Analysis Methods
It was not possible to collect fresh rock samples in the field, as the shallow porphyry in the Yanghuidongzi copper deposit experienced varying degrees of hydrothermal alteration. The sample analyzed in this paper is the ore-bearing granodiorite porphyry (YHD3) from the altered zone H3 (Figure 2a). The rock underwent a certain degree of hydrothermal alteration and has a massive structure, metamorphic texture, residual plaque-matrix crystallite texture, and euhedral-granular texture ( Figure 2d). The rock is composed of phenocrysts and a matrix. The phenocrysts are composed of quartz, feldspar pseudomorph, and biotite pseudomorph, with particle sizes ranging from 0.5 mm to 1.0 mm. The original euhedral platy feldspar is decomposed into sericite, muscovite, and quartz, among others. The altered minerals are fine in size, appearing in the form of aggregates. The original leafy biotite appears to be an illusion after being replaced by muscovite, carbonate, quartz, and limonite. The original leaf-like biotites appear as pseudomorph after being replaced by muscovite, carbonate, quartz and limonite. The matrix consists mainly of feldspar and quartz, which develop muscovitization, sericitization, quartzization, carbonation, and limonitization. Although the rock has undergone a certain degree of alteration, its granitic texture and the crystal form of its original minerals are still substantially retained.

Sample Collection and Analysis Methods
It was not possible to collect fresh rock samples in the field, as the shallow porphyry in the Yanghuidongzi copper deposit experienced varying degrees of hydrothermal alteration. The sample analyzed in this paper is the ore-bearing granodiorite porphyry (YHD3) from the altered zone H3 (Figure 2a). The rock underwent a certain degree of hydrothermal alteration and has a massive structure, metamorphic texture, residual plaque-matrix crystallite texture, and euhedral-granular texture (Figure 2d). The rock is composed of phenocrysts and a matrix. The phenocrysts are composed of quartz, feldspar pseudomorph, and biotite pseudomorph, with particle sizes ranging from 0.5 mm to 1.0 mm. The original euhedral platy feldspar is decomposed into sericite, muscovite, and quartz, among others. The altered minerals are fine in size, appearing in the form of aggregates. The original leafy biotite appears to be an illusion after being replaced by muscovite, carbonate, quartz, and limonite. The original leaf-like biotites appear as pseudomorph after being replaced by muscovite, carbonate, quartz and limonite. The matrix consists mainly of feldspar and quartz, which develop muscovitization, sericitization, quartzization, carbonation, and limonitization. Although the rock has undergone a certain degree of alteration, its granitic texture and the crystal form of its original minerals are still substantially retained.
Zircon sorting was carried out in the laboratory of the Regional Geological Survey Institute of Hebei Province (Langfang, China). Almost 500 kg of the sample was crushed, panned, electromagnetically selected, and subjected to heavy liquid separation. Zircons with no obvious cracks, less inclusions, and intact crystal forms were selected under a binocular microscope. The target zircon cathodoluminescence (CL) image and zircon U-Pb dating were carried out at the Key Laboratory of Mineral Resources Evaluation in Northeast Asia, Ministry of Land and Resources, Jilin University, Changchun, China. Helium was used as a carrier gas to provide efficient aerosol to the ICP and minimize aerosol deposition around the ablation site and in the transport tube [26,27]. Argon was used as the supplementary gas and mixed with the carrier gas via a T-connector before entering the ICP. A spot size of 32 µm and a 7 Hz repetition rate were used for the analyses. The standard zircon 91500 [28] was used as an external standard for the U-Pb analyses. Isotopic rations were calculated using the GLITTER program (version 4.0, GEOMOC National Laboratory, Sydney, New South Wales, Australia) with a common Pb correction, following the method of Yuan et al. [29]. Uncertainties of the isotope ratios were assigned with a 1σ error, and weighted mean ages were calculated at a 1σ confidence level. The age calculation and concordia diagram plotting were processed using the ISOPLOT program (Version 3.0, Berkeley Geochronology Center, Berkeley, CA, USA) [30].
The zircon Lu-Hf isotopic composition analyses were carried out at Nanjing FocuMS Technology Co. Ltd. (Nanjing, China) with a RESOlution LR 193 nm ArF excimer laser (Australian Scientific Instruments, Canberra, Australia) and a Nu Plasma II MC-ICP-MS (Nu Instruments, Wrexham, Wales, UK). During the experiment, helium was used as the carrier gas for the ablation material, and the laser beam's spot diameter was 50 µm. The internationally accepted standard zircon (91500) was used as the reference material in this test [31]. Detailed analytical procedures are described in Wu et al. [32]. The 176 Hf/ 177 Hf value of the standard zircon (91500) tested in this experiment was 0.2822906 ± 12 (1δ), which is consistent with the value of the predecessor [33] within the error range. In the calculation of the εHf(t) values, the 176 Hf/ 177 Hf and 176 Lu/ 177 Hf ratios of present-day chondrite and the depleted mantle were (0.0332, 0.282772) and (0.0384, 0.28325), respectively [34,35]. The two-stage Hf model ages (T DM2 ) were calculated by adopting 176 Lu/ 177 Hf = 0.015 for the average continental crust [36].

Zircon Morphology
Zircon CL images with their numbers are shown in Figure 3. The zircon grains (YHD3) are colorless and euhedral prismatic, with lengths of about 100-230 µm and aspect ratios of about 2-4.5. All zircons have strong CL and develop oscillatory zoning. The rims of the zircons are finely oscillatory zoned, while their cores are faint and broadly zoned, similar to typical the features of magmatic zircons [17,37]. cracks, less inclusions, and intact crystal forms were selected under a binocular microscope. The target zircon cathodoluminescence (CL) image and zircon U-Pb dating were carried out at the Key Laboratory of Mineral Resources Evaluation in Northeast Asia, Ministry of Land and Resources, Jilin University, Changchun, China. Helium was used as a carrier gas to provide efficient aerosol to the ICP and minimize aerosol deposition around the ablation site and in the transport tube [26,27]. Argon was used as the supplementary gas and mixed with the carrier gas via a T-connector before entering the ICP. A spot size of 32 µm and a 7 Hz repetition rate were used for the analyses. The standard zircon 91500 [28] was used as an external standard for the U-Pb analyses. Isotopic rations were calculated using the GLITTER program (version 4.0, GEOMOC National Laboratory, Sydney, New South Wales, Australia) with a common Pb correction, following the method of Yuan et al. [29]. Uncertainties of the isotope ratios were assigned with a 1σ error, and weighted mean ages were calculated at a 1σ confidence level. The age calculation and concordia diagram plotting were processed using the ISOPLOT program (Version 3.0, Berkeley Geochronology Center, Berkeley, CA, USA) [30]. The zircon Lu-Hf isotopic composition analyses were carried out at Nanjing FocuMS Technology Co. Ltd. (Nanjing, China) with a RESOlution LR 193 nm ArF excimer laser (Australian Scientific Instruments, Canberra, Australia) and a Nu Plasma II MC-ICP-MS (Nu Instruments, Wrexham, Wales, UK). During the experiment, helium was used as the carrier gas for the ablation material, and the laser beam's spot diameter was 50 µm. The internationally accepted standard zircon (91500) was used as the reference material in this test [31]. Detailed analytical procedures are described in Wu et al. [32]. The 176 Hf/ 177 Hf value of the standard zircon (91500) tested in this experiment was 0.2822906 ± 12 (1δ), which is consistent with the value of the predecessor [33] within the error range. In the calculation of the εHf(t) values, the 176 Hf/ 177 Hf and 176 Lu/ 177 Hf ratios of present-day chondrite and the depleted mantle were (0.0332, 0.282772) and (0.0384, 0.28325), respectively [34,35]. The two-stage Hf model ages (TDM2) were calculated by adopting 176 Lu/ 177 Hf = 0.015 for the average continental crust [36].

Zircon Morphology
Zircon CL images with their numbers are shown in Figure 3. The zircon grains (YHD3) are colorless and euhedral prismatic, with lengths of about 100-230 µm and aspect ratios of about 2-4.5. All zircons have strong CL and develop oscillatory zoning. The rims of the zircons are finely oscillatory zoned, while their cores are faint and broadly zoned, similar to typical the features of magmatic zircons [17,37].

Zircon U-Pb Age
In this paper, a total of 38 points were analyzed ( Table 1). The content of Th in the zircons ranged from 33.43 ppm to 259.75 ppm, and the content of U ranged from 61.14 ppm to 815.29 ppm.

Zircon U-Pb Age
In this paper, a total of 38 points were analyzed ( Table 1). The content of Th in the zircons ranged from 33.43 ppm to 259.75 ppm, and the content of U ranged from 61.14 ppm to 815.29 ppm. The Th/U ratios of the zircons were all greater than 0.1 (0.11-0.68), indicating that most of the zircons had an igneous origin. On the basis of the zircon U-Pb isotope analysis, we found that 33 points had a good concordant relationship. The 206 Pb/ 238 U values from the 33 points are listed in Table 1, which shows that the zircon's U-Pb age is 189.6 ± 1.0 Ma (MSWD = 0.93, n = 33) (Figure 4). The Th/U ratios of the zircons were all greater than 0.1 (0.11-0.68), indicating that most of the zircons had an igneous origin. On the basis of the zircon U-Pb isotope analysis, we found that 33 points had a good concordant relationship. The 206 Pb/ 238 U values from the 33 points are listed in Table 1, which shows that the zircon's U-Pb age is 189.6 ± 1.0 Ma (MSWD = 0.93, n = 33) (Figure 4).

Zircon Trace Element Characteristics
The trace element analysis results of the ore-bearing porphyry (YHD3) zircons are shown in Table 2

Zircons Hf Isotopic Composition
Based on the LA-ICP-MS zircon U-Pb data, we analyzed the zircon Lu-Hf isotope on the same spots of the concordant grains (YHD3). The results of the Hf isotope are shown in Table 3. The 176 Lu/ 177 Hf ratios of the Yanghuidongzi zircons were lower (0.000443-0.001193, average value = 0.000654). The 176 Hf generated by 176 Lu is very rare, which indicates that most of the zircons have little accumulation of radioactive Hf after the zircons formation. Because of the lower 176 Hf/ 177 Hf ratios in the zircons, we assume that the measured values of 176 Hf/ 177 Hf are equivalent to the initial 176 Hf/ 177 Hf ratios of the zircon [20]. Furthermore, the εHf(t) value of the Yanghuidongzi zircons was

Zircon Trace Element Characteristics
The trace element analysis results of the ore-bearing porphyry (YHD3) zircons are shown in Table 2 The Th/U ratios of the zircons were all greater than 0.1 (0.11-0.68), indicating that most of the zircons had an igneous origin. On the basis of the zircon U-Pb isotope analysis, we found that 33 points had a good concordant relationship. The 206 Pb/ 238 U values from the 33 points are listed in Table 1, which shows that the zircon's U-Pb age is 189.6 ± 1.0 Ma (MSWD = 0.93, n = 33) (Figure 4).

Zircon Trace Element Characteristics
The trace element analysis results of the ore-bearing porphyry (YHD3) zircons are shown in Table 2

Zircons Hf Isotopic Composition
Based on the LA-ICP-MS zircon U-Pb data, we analyzed the zircon Lu-Hf isotope on the same spots of the concordant grains (YHD3). The results of the Hf isotope are shown in Table 3. The 176 Lu/ 177 Hf ratios of the Yanghuidongzi zircons were lower (0.000443-0.001193, average value = 0.000654). The 176 Hf generated by 176 Lu is very rare, which indicates that most of the zircons have little accumulation of radioactive Hf after the zircons formation. Because of the lower 176 Hf/ 177 Hf ratios in the zircons, we assume that the measured values of 176 Hf/ 177 Hf are equivalent to the initial 176 Hf/ 177 Hf ratios of the zircon [20]. Furthermore, the εHf(t) value of the Yanghuidongzi zircons was

Zircons Hf Isotopic Composition
Based on the LA-ICP-MS zircon U-Pb data, we analyzed the zircon Lu-Hf isotope on the same spots of the concordant grains (YHD3). The results of the Hf isotope are shown in Table 3. The 176 Lu/ 177 Hf ratios of the Yanghuidongzi zircons were lower (0.000443-0.001193, average value = 0.000654). The 176 Hf generated by 176 Lu is very rare, which indicates that most of the zircons have little accumulation of radioactive Hf after the zircons formation. Because of the lower 176 Hf/ 177 Hf ratios in the zircons, we assume that the measured values of 176 Hf/ 177 Hf are equivalent to the initial 176 Hf/ 177 Hf ratios of the zircon [20]. Furthermore, the ε Hf (t) value of the Yanghuidongzi zircons was 4.4-7.0 (mean = 5.8), the 176 Hf/ 177 Hf value was 0.282786-0.282854 (mean = 0.282820), and the two-stage Hf model ages (T DM2 ) ranged from 783 Ma to 943 Ma (mean = 861 Ma).

Zircon Genesis
Zircon is a highly stable mineral [40] and can retain its primary physical and chemical properties in various geological processes. Therefore, the age and genetic information of the original rock can still be obtained by using the zircons in the altered rocks as long as the alteration does not destroy the structure and composition of the magmatic zircons.
In this paper (Sections 4.1 and 4.2), the CL image features and Th/U value of zircons from the Yanghuidongzi copper deposit show that the zircons were mainly derived from magma. In addition, since zircon is an important host mineral of U, Th, and REE in rocks [41][42][43], the content characteristics of these elements are also used to determine the zircon's genesis. The comparisons of the trace element characteristics of typical magmatic zircons and hydrothermal zircons by different researchers show some common features [38,44,45]. The REE patterns of magmatic zircons are generally characterized by a lower concentration of REE, with a steeper LREE (i.e., higher (Sm/La) N ) and higher Ce anomalies than hydrothermal zircons. The concentration of Th and U in magmatic zircons is commonly lower than that in hydrothermal zircons.
Here, we compare the REE patterns of zircons from the Yanghuidongzi copper deposit with those of the Xianshuiquan zircons [38] (Figure 5b). The REE content of the zircons in Yanghuidongzi is consistent with that of the magmatic zircons in Xianshuiquan magma and significantly lower than that of the hydrothermal zircons in Xianshuiquan. Most zircons in Yanghuidongzi have steeper LREE and higher positive Ce anomalies than hydrothermal zircons in Xianshuiquan. However, a small number of zircons in Yanghuidongzi have gentle LREE and weakly positive Ce anomalies, which indicates that some zircons may experience weak hydrothermal action.
We also compare the Th and U contents of the zircons in Yanghuidongzi with the Th and U contents of the typical magmatic zircon and hydrothermal zircon in the Bobby Plain [44] and Xianshuiquan [38]. The results show that the Th and U contents of the zircons in Yanghuidongzi are similar to those of the magmatic zircons and distinct from those of the hydrothermal zircons ( Figure 6). Here, we compare the REE patterns of zircons from the Yanghuidongzi copper deposit with those of the Xianshuiquan zircons [38] (Figure 5b). The REE content of the zircons in Yanghuidongzi is consistent with that of the magmatic zircons in Xianshuiquan magma and significantly lower than that of the hydrothermal zircons in Xianshuiquan. Most zircons in Yanghuidongzi have steeper LREE and higher positive Ce anomalies than hydrothermal zircons in Xianshuiquan. However, a small number of zircons in Yanghuidongzi have gentle LREE and weakly positive Ce anomalies, which indicates that some zircons may experience weak hydrothermal action.
We also compare the Th and U contents of the zircons in Yanghuidongzi with the Th and U contents of the typical magmatic zircon and hydrothermal zircon in the Bobby Plain [44] and Xianshuiquan [38]. The results show that the Th and U contents of the zircons in Yanghuidongzi are similar to those of the magmatic zircons and distinct from those of the hydrothermal zircons ( Figure  6).
Combined with above analysis, the zircons in Yanghuidongzi are of magmatic origin. Therefore, the zircon U-Pb ages in this paper have been affected little by later alterations and could represent the formation age of the porphyry before mineralization.

Metallogenic Age and Dynamics Background
NE China is characterized by voluminous Mesozoic granitoids, with a main diagenetic age of 160-190 Ma [14,23], forming a N-S granite belt in the eastern part of NE China (Figure 7a). Importantly, a series of Early-Middle Jurassic porphyry deposits were formed in the granite belt, consisting of an N-S porphyry copper-molybdenum metallogenic belt (Figure 7a). Combined with the chronological results in this paper, the Yanghuidongzi copper deposits (189.6 ± 1.0 Ma) are closely related to the granodiorite porphyry, which is consistent with the large-scale granite diagenetic and metallogenic ages in the area. Furthermore, the characteristics of fluid inclusion and H-O isotopes in the ore-bearing quartz veins proved that the ore-forming fluids of the Yanghuidongzi copper deposits were mainly derived from magma [22]. Therefore, the zircon U-Pb age of the granodiorite porphyry can represent both the age of the porphyry intrusion and the upper age of the magma-hydrothermal system. We hypothesized that the Yanghuidongzi porphyry copper deposit formed during the Early Jurassic (189.6 ± 1.0 Ma) and coincided with the magmatic activity in the Early Yanshanian. Combined with above analysis, the zircons in Yanghuidongzi are of magmatic origin. Therefore, the zircon U-Pb ages in this paper have been affected little by later alterations and could represent the formation age of the porphyry before mineralization.

Metallogenic Age and Dynamics Background
NE China is characterized by voluminous Mesozoic granitoids, with a main diagenetic age of 160-190 Ma [14,23], forming a N-S granite belt in the eastern part of NE China (Figure 7a). Importantly, a series of Early-Middle Jurassic porphyry deposits were formed in the granite belt, consisting of an N-S porphyry copper-molybdenum metallogenic belt (Figure 7a). Combined with the chronological results in this paper, the Yanghuidongzi copper deposits (189.6 ± 1.0 Ma) are closely related to the granodiorite porphyry, which is consistent with the large-scale granite diagenetic and metallogenic ages in the area. Furthermore, the characteristics of fluid inclusion and H-O isotopes in the ore-bearing quartz veins proved that the ore-forming fluids of the Yanghuidongzi copper deposits were mainly derived from magma [22]. Therefore, the zircon U-Pb age of the granodiorite porphyry can represent both the age of the porphyry intrusion and the upper age of the magma-hydrothermal system. We hypothesized that the Yanghuidongzi porphyry copper deposit formed during the Early Jurassic (189.6 ± 1.0 Ma) and coincided with the magmatic activity in the Early Yanshanian. The geochemical elements of the porphyry rocks from the Yanghuidongzi copper deposits indicate that the mineralized granites are peraluminous calc-alkaline series I-type granitoids, characterized by an enrichment of large ion lithophile elements (LILE) and a depletion of high field strength elements (HFSE), which have similar geochemical characteristics to the subduction zone magma [21]. Furthermore, the trace elements Rb vs. (Y + Nb) and Nb vs. Y in the deposits show that the porphyry rocks were derived from volcanic arc and collisional granite, which indicates that the Yanghuidongzi copper deposit is likely to be an interaction product of plate subduction and magmatism during geological evolution [21].
The final closure of the Paleo-Asian Ocean took place during the Late Permian-Early Triassic [49,50]. After the closure of the Paleo-Asian Ocean in NE China, NE China entered the evolutionary stage of the circum-Pacific tectonic regime and the Mongolia-Okhotsk tectonic regime [51]. In the Early Jurassic, NE China experienced two subduction events: The Paleo-Pacific Plate subduction [46] and the Mongol-Okhotsk Plate subduction [52,53]. According to the temporal and spatial distribution of the Mesozoic volcanic rocks in the Northeast, Xu et al. [46] reported that the influence of the spatial extent of the Pacific Rim tectonic system was mainly in the Songliao Basin and to its east; the influencing scope of the Mongolia-Okhotsk tectonic system was to west of the Songliao basin and the northern margin of the North China Craton. However, the Yanghuidongzi The geochemical elements of the porphyry rocks from the Yanghuidongzi copper deposits indicate that the mineralized granites are peraluminous calc-alkaline series I-type granitoids, characterized by an enrichment of large ion lithophile elements (LILE) and a depletion of high field strength elements (HFSE), which have similar geochemical characteristics to the subduction zone magma [21]. Furthermore, the trace elements Rb vs. (Y + Nb) and Nb vs. Y in the deposits show that the porphyry rocks were derived from volcanic arc and collisional granite, which indicates that the Yanghuidongzi copper deposit is likely to be an interaction product of plate subduction and magmatism during geological evolution [21].
The final closure of the Paleo-Asian Ocean took place during the Late Permian-Early Triassic [49,50]. After the closure of the Paleo-Asian Ocean in NE China, NE China entered the evolutionary stage of the circum-Pacific tectonic regime and the Mongolia-Okhotsk tectonic regime [51]. In the Early Jurassic, NE China experienced two subduction events: The Paleo-Pacific Plate subduction [46] and the Mongol-Okhotsk Plate subduction [52,53]. According to the temporal and spatial distribution of the Mesozoic volcanic rocks in the Northeast, Xu et al. [46] reported that the influence of the spatial extent of the Pacific Rim tectonic system was mainly in the Songliao Basin and to its east; the influencing scope of the Mongolia-Okhotsk tectonic system was to west of the Songliao basin and the northern margin of the North China Craton. However, the Yanghuidongzi deposit is located to the east of the Songliao Basin, next to the Paleo-Pacific subduction zone, and far from the Mongolian-Okhotsk suture zone (Figure 7b). Hence, the Yanghuidongzi deposit is mostly related to the magmatism caused by the subduction of the Paleo-Pacific plate. Therefore, we can infer that the N-S Early-Middle Jurassic granite belt and porphyry deposits (including the Yanghuidongzi deposit) with similar directions to the subduction zone were formed in the eastern part of NE China during the subduction of the Paleo-Pacific plate to the East Asian continent.

Magma Source of the Ore-Bearing Porphyry
The consistency of the geochemical behavior of Nb-Ta and Zr-Hf and the ratios of Nb/Ta and Zr/Hf generally do not change in different geological processes, so their ratios can be used as powerful discriminants between different sources [54]. The Yanghuidongzi porphyry has Zr/Hf (35.48-40.0, average 38.38) and Nb/Ta (7.5-13.6, average 10.27) ratios [21] that are closer to the continental crustal values (13.4 and 36.0, respectively [55]), rather than the chondritic values (34.3 ± 0.3 and 19.9 ± 0.6, respectively [56]). This indicates that the primary magma that formed the Yanghuidongzi porphyry was generated by the partial melting of the crust material.
The Yanghuidongzi porphyry have a positive ε Hf (t) value (4.4-7.0) and a large 176 Hf/ 177 Hf ratio (0.282786-0.282854), with two-stage Hf model ages (T DM2 ) ranging from 783 Ma to 943 Ma. The ε Hf (t) and T DM2 values are relatively concentrated, reflecting the isotopic uniformity of the magma source in this mining area. In addition, in the Hf isotope evolution diagram (Figure 8a,b), all points are below the line of the depleted mantle and within the ε Hf (t) distribution region of the Phanerozoic igneous rocks in the eastern XMOB (Figure 8a). Most of Phanerozoic igneous rocks in the eastern XMOB have positive ε Nd (t) values [57,58] and positive ε Hf (t) values [59,60] with a younger (Nd and Hf) model age (generally 0.5-1.0 Ga), indicating that these igneous rocks were probably formed by the partial melting of Precambrian crustal material [58], and the eastern XMOB may have undergone large-scale crustal growth from the Neoproterozoic to the Phanerozoic [60]. deposit is located to the east of the Songliao Basin, next to the Paleo-Pacific subduction zone, and far from the Mongolian-Okhotsk suture zone (Figure 7b). Hence, the Yanghuidongzi deposit is mostly related to the magmatism caused by the subduction of the Paleo-Pacific plate. Therefore, we can infer that the N-S Early-Middle Jurassic granite belt and porphyry deposits (including the Yanghuidongzi deposit) with similar directions to the subduction zone were formed in the eastern part of NE China during the subduction of the Paleo-Pacific plate to the East Asian continent.

Magma Source of the Ore-Bearing Porphyry
The consistency of the geochemical behavior of Nb-Ta and Zr-Hf and the ratios of Nb/Ta and Zr/Hf generally do not change in different geological processes, so their ratios can be used as powerful discriminants between different sources [54]. The Yanghuidongzi porphyry has Zr/Hf (35.48-40.0, average 38.38) and Nb/Ta (7.5-13.6, average 10.27) ratios [21] that are closer to the continental crustal values (13.4 and 36.0, respectively [55]), rather than the chondritic values (34.3 ± 0.3 and 19.9 ± 0.6, respectively [56]). This indicates that the primary magma that formed the Yanghuidongzi porphyry was generated by the partial melting of the crust material.
The Yanghuidongzi porphyry have a positive εHf(t) value (4.4-7.0) and a large 176 Hf/ 177 Hf ratio (0.282786-0.282854), with two-stage Hf model ages (TDM2) ranging from 783 Ma to 943 Ma. The εHf(t) and TDM2 values are relatively concentrated, reflecting the isotopic uniformity of the magma source in this mining area. In addition, in the Hf isotope evolution diagram (Figure 8a,b), all points are below the line of the depleted mantle and within the εHf(t) distribution region of the Phanerozoic igneous rocks in the eastern XMOB ( Figure. 8a). Most of Phanerozoic igneous rocks in the eastern XMOB have positive εNd(t) values [57,58] and positive εHf(t) values [59,60] with a younger (Nd and Hf) model age (generally 0.5-1.0 Ga), indicating that these igneous rocks were probably formed by the partial melting of Precambrian crustal material [58], and the eastern XMOB may have undergone large-scale crustal growth from the Neoproterozoic to the Phanerozoic [60].
The above analysis reveals that the primary magma that formed the Early Jurassic granodiorite porphyry in the mining area was generated by the partial melting of juvenile crustal material from the depleted mantle in the Neoproterozoic.

Conclusion
The combination of the zircon U-Pb and Hf isotopes of ore-bearing granodiorite porphyry from the Yanghuidongzi copper deposits provides an effective way to determine the ore-forming age, metallogenic dynamic background, and magma source.
(1) The zircon U-Pb age of the ore-bearing granite porphyry indicates that the Yanghuidongzi porphyry copper deposit was formed in the Early Jurassic (189.6 ± 1.0 Ma) and corresponds to the magmatic activity time in the area. The above analysis reveals that the primary magma that formed the Early Jurassic granodiorite porphyry in the mining area was generated by the partial melting of juvenile crustal material from the depleted mantle in the Neoproterozoic.

Conclusion
The combination of the zircon U-Pb and Hf isotopes of ore-bearing granodiorite porphyry from the Yanghuidongzi copper deposits provides an effective way to determine the ore-forming age, metallogenic dynamic background, and magma source.
(1) The zircon U-Pb age of the ore-bearing granite porphyry indicates that the Yanghuidongzi porphyry copper deposit was formed in the Early Jurassic (189.6 ± 1.0 Ma) and corresponds to the magmatic activity time in the area.
(2) The background analysis of ore-forming dynamics suggests that the formation of the Yanghuidongzi copper deposit was related to the subduction of the Paleo-Pacific plate.
(3) The Yanghuidongzi ore-bearing porphyry zircons have a positive ε Hf (t) value (4.4-7.0) and a large 176 Hf/ 177 Hf ratio (0.282786-0.282854), with the two-stage Hf model age ranging from 783 Ma to 943 Ma, which indicates that the Early Jurassic granodiorite porphyry in the mining area was formed by partial melting of the newly grown crustal material from the depleted mantle during the Neoproterozoic.