The Late Mesozoic granodiorite and polymetallic mineralization in southern Anhui Province, China: A perspective from apatite geochemistry

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The Late Mesozoic granodiorite and polymetallic mineralization in southern Anhui Province, China: A perspective from apatite geochemistry Lin Qian a, Yu Wang a, Jiancheng Xie a,*, Weidong Sun b,c,d a School of Resources and Environmental Engineering, Hefei University of Technology, Hefei, 230009, China Center of Deep Sea Research, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China c Laboratory for Marine Mineral Resources, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China d CAS Center for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences, Beijing, 100101, China b

Received 13 October 2019; revised 12 November 2019; accepted 13 November 2019 Available online ▪ ▪ ▪

Abstract The region of southern Anhui Province (SAP) is one of Late Mesozoic magmatic belts and copper-molybdenum-gold-tungsten polymetallic ore districts in China, but the relationship of polymetallic mineralization and related granodiorite remains unclear. Previous studies indicate that apatite can be an indicator for magmatic evolution and mineral exploration. In this study, apatites from the SAP ore-bearing granodiorites were investigated using observations from the electron microscope, electron probe microanalysis (EPMA), laser-ablation inductively-coupled plasmamass spectrometry (LA-ICP-MS). The studied apatite samples identified as fluorapatite, show high F (2.69e4.13 wt.%) and low Cl contents (mainly<0.2 wt.%). These apatites also have high La/Y (0.41e4.69) and dEu (0.13e0.70) values, and low (Sm/Nd)N values (0.34e0.81), indicating that the SAP magma was derived from mafic I-type melt. The REE patterns, negative Eu anomalies, the negative dEu and dCe correlation, and high logfO2 values (
10.5 to
13.8) of apatites studied, further indicate that the SAP granodiorites had originated from mantlederived magmas mixing with the lower crustal components in high oxygen fugacity environment. The results indicate that the Sr/Y and dEu values of apatite can be a good indicator to distinguish adakitic rocks from non-adakitic rocks. Moreover, the dEu value and Cl content in apatite can be effectively used to discriminate the unmineralized rocks and ore deposit types. Copyright © 2019, Guangzhou Institute of Geochemistry. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Keywords: In-situ geochemistry of apatite; Granodiorite; Polymetallic mineralization; Late Mesozoic; Southern Anhui Province

1. Introduction Apatite, Ca5(PO4)3(OH, F, Cl), occurs widely as an accessory mineral in granitic rocks, and contains halogens (F, Cl), S and various trace elements (e.g., Sr, Mn, U, Th), as well as rare earths elements (REE) and Y by substitution in anion and cation sites (Ding et al., 2015). Apatite could effectively record and preserve the formation information of parental * Corresponding author. School of Resources and Environmental Engineering, Hefei University of Technology, Hefei, 230009, China. E-mail addresses: [email protected] (L. Qian), geowangyu@ 163.com (Y. Wang), [email protected] (J. Xie), weidongsun@gig. ac.cn (W. Sun). Peer review under responsibility of Guangzhou Institute of Geochemistry.

magma, and trace petrogenetic and metasomatic processes, which are not always evident using whole-rock methods (Belousova et al., 2002; Miles et al., 2014; Pan et al., 2016; Jiang et al., 2018; Xie et al., 2018), because it is stable in various geological environments and processes (Chew et al., 2016). Previous researches indicate that apatite had used indicators as a petrogenetic, a proxy for the redox state of magma, and mineral exploration, making it key tracer for magmatic origin, magmatic evolution and mineralization (Belousova et al., 2002; Chew et al., 2016; Ding et al., 2015; Mao et al., 2016; Miles et al., 2014; Pan et al., 2016; Xie et al., 2018; Yang et al., 2018). Southern Anhui Province (SAP) within the eastern part of the Yangtze Craton (Fig. 1a), has undergone multiple orogenic

https://doi.org/10.1016/j.sesci.2019.11.006 2451-912X/Copyright © 2019, Guangzhou Institute of Geochemistry. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NCND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Please cite this article as: Qian, L et al., The Late Mesozoic granodiorite and polymetallic mineralization in southern Anhui Province, China: A perspective from apatite geochemistry, Solid Earth Sciences, https://doi.org/10.1016/j.sesci.2019.11.006

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movements since Meso-Neoproterozoic (Xie et al., 2017; Yan et al., 2017). During Late Mesozoic, it was characterized by extensive magmatism and significant CueMoeAueW polymetallic mineralization in the SAP (Fig. 1b) (Xie et al., 2017, 2019; Yan et al., 2017). Field investigation and extensive geochronological data, have revealed two-stage magmatism in the SAP, which was divided into 153-137 Ma of early-stage (Itype granodiorite) and 134-123 Ma of late-stage (A-type granite) (Xie et al., 2017, 2019). Previous studies point out that the CueMoeAueW polymetallic mineralization was closely associated with and genetically related to the early-stage granodiorites in the SAP (Xie et al., 2017, 2019; Yan et al., 2017). However, the relationship of these polymetallic deposits and the related granodiorites remains unclear. Moreover, previous researches focused more on the geochronology, whole rock and isotopic geochemistry (Xie et al., 2017; Yan et al., 2017), but there are rare details on the elemental compositions of apatite from the intrusive rocks in the SAP. In this paper, we investigate the petrography of the orebearing granodiorite with emphasis on the apatite in the SAP. The geochemical characteristics of the apatite are summarized and discussed, based on in situ elemental

compositions of the studied apatite from these granodiorites, together with previously published apatite data. The new data provide useful petrogenetic information and understand relationship of polymetallic mineralization and the granodiorite in the SAP. 2. Geological setting The SAP within the eastern of the Yangtze Craton which is bordered by the Cathaysia Block in the south, the Sulu-Dabie Orogenic Belt in the north and the Paleo-Pacific Plate in the east (Fig. 1a), includes the lower Yangtze depression, the Jiangnan uplift and the Qiantang depression (Fig. 1b) (Xie et al., 2017). It has undergone Jinningian, Caledonian, Hercynian, Indosinian and Yanshanian multiple stages of tectonic movements (Yan et al., 2017). The present tectonic framework in the SAP is dominantly established by the Indosinian (Late Permian to Triassic) and Yanshanian (Jurassic to Early Cretaceous) events (Yan et al., 2017). The outcrops of the SAP are Meso-Neoproterozoic basement and Sinian to Cretaceous sedimentary strata (Fig. 1b). The former mainly distributed in the southern SAP, consists of a series of low-grade

Fig. 1. Geological sketch map of the southern Anhui Province (Modified from Xie et al., 2017). Tectonic divisions: I-the lower Yangtze depression, II-Jiangnan uplift, III-Qiantang depression. Faults: F1-Jiangnan fault zone, F2-Zhouwang fault, F3-Baikeshu fault, F4-Qimen-Qiankou fault, F5-Sanyang fault, F6-Gandongbei fault. Please cite this article as: Qian, L et al., The Late Mesozoic granodiorite and polymetallic mineralization in southern Anhui Province, China: A perspective from apatite geochemistry, Solid Earth Sciences, https://doi.org/10.1016/j.sesci.2019.11.006

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metamorphic rocks, such as slate, phyllite, metasiltstone, metasandstone and felsic volcanic rock (Xie et al., 2017) (Fig. 1b). The latter is composed of Sinian to lower Triassic marine and Upper Triassic to Cretaceous continental sedimentary sequences, mainly distributed in northern of the SAP and around the Huangshan city (Xie et al., 2017) (Fig. 1b). The ultrabasic-acidic magmatic activity in the SAP was mainly concentrated on the Neoproterozoic (Jinningian) and the Late Mesozoic (Yanshanian) (Fig. 1b). The Jinningian volcanic rocks include Xicun (spillite-keratophyre), Xikou (volcanic-fine clastic rocks), Zhoujiacun (dacitic crystal tuff), Jingtan (dacite and rhyolite), and Puling (andesite-basalt) Formations, with ages of 860e820 and 780e740 Ma, respectively (Yan et al., 2017). The Jinningian intrusions around Huangshan city, include 830-820 Ma granodioritic (e.g., Xucun, Xiuning) and 780-760 Ma granitic (e.g., Lingshan, Shiershan) intrusions (Wang et al., 2014). Comparatively, the Yanshanian magmatic rocks are most extensively distributed in the SAP, and form a series of composite intrusions, such as, Qingyang-Jiuhuashan, Jingde, Langqiao, and Huangshan-Taiping intrusions that were intruded into lowgrade metamorphosed rocks and Paleozoic-Triassic sedimentary units (Xie et al., 2017) (Fig. 1b). The composite intrusions are distributed on both sides of the Jiangnan fault zone (F1) and are separated into intermediate-acidic and acidic intrusive rocks (Xie et al., 2017). The intermediate-acidic intrusive rocks are concentrated at 153-137 Ma (peak 140 Ma) with its predominant calc-alkaline series I-type granodiorites, while the acidic intrusive rocks are mainly formed in 134e123 Ma (peak 128 Ma) with its dominant alkaline series A-type granites (Xie et al., 2017 and references therein). The granodiorite intrusions are spatially associated with the polymetallic

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ore deposits, while the granite intrusions are generally orebarren (Xie et al., 2017) (Fig. 1b). Early mineral exploration in the SAP was not high and only a few small metallic deposits were discovered. In recent decade, a series of medium-large CueWeMo polymetallic ore deposits, containing >300,000 tons of WO3, such as Gaojiabang large CueMoeW deposit (Jiang et al., 2009), Dongyuan and Xiaoyao large WeMo deposits (Wang et al., 2011; Su et al., 2018), have been explored in the SAP (Fig. 1b). Deposits controlled by the NEeSW trending tectonic-magmatic belt, show a spatial distribution around composite intrusions (Fig. 1b), such as Gaojiabang deposit related to Qingyang (QY) granodiorite (Jiang et al., 2009), Aozishan WeMo deposit related to Jingde (JD) granodiorite (Zhang et al., 2012), Wuxi polymetallic deposit related to Langqiao (LQ) granodiorite (Li et al., 2014), and Pailou MoeAu polymetallic deposit related to Pailou (PL) granodiorite (Xie et al., 2019). Types of the ore deposits in the SAP mainly include skarn (e.g., Xiaoyao deposit) and porphyry (e.g., Pailou, Dongyuan, Goajiabang, Aozishan and Wuxi deposits) types. Recent studies have shown that the porphyry and skarn deposits have molybdenite Re-Os ages of 146e142 Ma (Su et al., 2018), supporting the view that they are genetically related to Late Mesozoic I-type granodiorites in the SAP (Xie et al., 2017, 2019; Yan et al., 2017). 3. Samples and analytical methods 3.1. Samples The four granodiorite samples in this study are collected from the surface fresh outcrops of LQ, JD, QY and PL

Fig. 2. Photomicrographs illustrating minerals of granodiorite samples in the SAP. (a) LQ, (b) JD, (c) QY, and (d) PL granodiorites. Abbreviations: Pl ¼ Plagioclase; Kfs ¼ K-feldspar; Qz ¼ Quartz; Bi ¼ Biotite; Hbl ¼ Hornblende; Ap ¼ Apatite; Zrn ¼ Zircon. Please cite this article as: Qian, L et al., The Late Mesozoic granodiorite and polymetallic mineralization in southern Anhui Province, China: A perspective from apatite geochemistry, Solid Earth Sciences, https://doi.org/10.1016/j.sesci.2019.11.006

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Table 1 Characteristics of granodiortie samples in the southern Anhui Province. Pluton

Shape

Lithology

Texture and Structure

Mineral components

Related deposits

Age (Ma)

Analytical methods

References

Langqiao

Batholith

Granodiorite

Medium- to coarse-grained, massive

Wuxi polymetallic deposit

139.5 ± 1.6

LA-ICP-MS

Xie et al. (2017)

Jingde

Batholith

Granodiorite

Medium- to coarse-grained, massive

Aozishan WeMo deposit

146.1 ± 1.5

LA-ICP-MS

Xie et al. (2017)

Qingyang

Batholith

Granodiorite

Medium- to coarse-grained, massive

Gaojiabang CueMo deposit

143.3 ± 2.3

LA-ICP-MS

Xie et al. (2017)

Pailou

Stock

Granodiorite

Medium-grained, massive

Plagioclase (40e45%), Quartz (20e25%), K-feldspar (15e25%), Biotite (5e10%), Amphibole (~5%) Plagioclase (35e40%), Quartz (~25%), K-feldspar (15e20%), Biotite (5e10%), Amphibole (3e5%) Plagioclase (~50%), K-feldspar (~20%), Quartz (~20%), Biotite (~10%), Amphibole (~5%) Plagioclase (40e45%), Quartz (~20%), K-feldspar (~15%), Biotite (~5%), Amphibole (3e5%)

Pailou MoeAupolymetallic deposit

149.8 ± 2.0

LA-ICP-MS

Xie et al. (2019)

Fig. 3. Backscattered electron (BSE) images of euhedral apatites from the granodiorites in the SAP.

intrusions in the SAP (Fig. 1b). These samples are grayish white, granular texture and massive structure, with the main component being plagioclase, quartz, K-feldspar, biotite, hornblende, and a small amount of accessory minerals (e.g., zircon and apatite) (Fig. 2). The main characteristics of these granodiorite samples in the SAP are shown in Table 1. Apatite grains from the granodiorite samples are grayish white, mostly euhedral to hexagonal, and 150e300 mm in length with 1:1e3:1 in length/width ratio (Fig. 3). They are usually present in the form of inclusions in biotite and quartz (Fig. 2), suggesting that the crystallization of apatite samples was in the early stage of magma evolution and was not affected by later fractional crystallization (Ding et al., 2015; Han et al., 2016). The above characteristics indicate that the studied apatite samples can offer petrogenetic information for the original magma of the granodiorites in the SAP. 3.2. Analytical methods The apatites studied in the study were separated from the SAP granodiorite samples using heavy liquid methods, followed by handpicked under a binocular microscope. The

apatite selected was mounted in epoxy resin, polished, and then examined using backscattered electron (BSE) images to pick euhedral targets for electron probe microanalysis and LAICP-MS analysis. Major elemental analysis of apatite was measured using a JEOL JXA-8230M electron microprobe at the School of Resources and Environmental Engineering, Hefei University of Technology, China. The test conditions are 15 kV acceleration voltage, 20 nA probe current, 5 mm beam spot diameter. Detection limit are: 0.032 wt. % for P2O5, 0.011 wt. % for SiO2, 0.01wt % for Cr2O3, 0.01 wt. % for TiO2, 0.02 wt. % for CaO, 0.03 wt. % for MnO, 0.01 wt. % for FeO, 0.01 wt. % for Na2O, 0.01 wt. % for K2O, 0.01 wt. % for F, and 0.01 wt. % for Cl. The trace element compositions in apatite were determined by LA-ICP-MS at the Key Laboratory of Mineralogy and Metallogeny, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences. The system is an Agilent 7500a ICPMS (using He gas) equipped with a Resonetics 193 nm ArFExcimer laser. The Ca content was measured using electron microprobe for the internal standard (Pan et al., 2016). The NIST612 grass standard was used as an external standard (Li

Please cite this article as: Qian, L et al., The Late Mesozoic granodiorite and polymetallic mineralization in southern Anhui Province, China: A perspective from apatite geochemistry, Solid Earth Sciences, https://doi.org/10.1016/j.sesci.2019.11.006

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Table 2 EPMA data of apatite from granodiorites in the southern Anhui province (wt. %). Sample

Na2O

K2 O

TiO2

Cr2O3

MnO

F

SiO2

P2O5

Cl

CaO

FeO

Total

LQ-2 LQ-3 LQ-4 LQ-5 LQ-6 LQ-7 LQ-8 LQ-9 LQ-10 JD-1 JD-2 JD-3 JD-4 JD-5 JD-6 JD-7 JD-8 JD-9 JD-10 QY-1 QY-2 QY-3 QY-4 QY-5 QY-6 QY-7 QY-8 QY-9 QY-10 PL-1 PL-2 PL-3 PL-4 PL-5 PL-6 PL-7 PL-8 PL-9 PL-10

0.10 0.07 0.07 0.02 0.05 0.09 0.06 0.06 0.02 0.15 0.06 0.07 0.08 0.12 0.08 0.09 0.03 0.03 0.09 0.18 0.08 0.07 0.12 0.11 0.16 0.08 0.08 0.13 0.13 0.02 0.09 0.08 0.08 0.06 0.06 0.07 0.10 0.09 0.03

0.02 0.00 0.01 0.00 0.01 0.02 0.00 0.00 0.00 0.00 0.00 0.01 0.01 0.03 0.01 0.03 0.00 0.02 0.00 0.00 0.00 0.02 0.00 0.03 0.01 0.00 0.00 0.00 0.00 0 0.03 0.03 0 0.02 0 0.01 0.02 0.01 0.02

0.00 0.00 0.03 0.00 0.00 0.01 0.00 0.00 0.03 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.04 0 0 0 0 0.02 0.03 0 0 0

0.00 0.01 0.04 0.02 0.00 0.00 0.00 0.00 0.03 0.02 0.00 0.02 0.00 0.00 0.01 0.00 0.00 0.06 0.03 0.02 0.00 0.01 0.00 0.00 0.00 0.03 0.00 0.02 0.00 0 0 0 0 0 0 0 0 0 0.02

0.37 0.30 0.21 0.29 0.29 0.17 0.41 0.28 0.37 0.47 0.43 0.30 0.28 0.36 0.28 0.36 0.33 0.33 0.38 0.36 0.26 0.27 0.31 0.21 0.17 0.22 0.25 0.02 0.15 0.23 0.27 0.05 0.21 0.09 0.35 0.22 0.3 0.36 0.2

3.21 3.44 4.03 3.15 3.23 2.76 3.09 3.07 3.00 3.48 4.13 3.36 3.54 4.03 3.58 3.52 3.36 3.33 3.11 2.69 3.23 3.34 3.30 3.09 2.89 3.41 3.38 3.27 3.77 3.87 3.09 3.43 2.84 2.75 2.93 3.12 3.23 3.00 3.57

0.05 0.08 0.01 0.12 0.05 0.04 0.07 0.06 0.02 0.07 0.03 0.01 0.26 0.06 0.21 0.35 0.43 1.48 0.09 0.20 0.12 0.41 0.10 0.17 0.01 0.10 0.18 0.13 0.13 0 0.21 0.13 0.11 0.03 0.2 0.12 0.08 0.19 0

41.7 41.3 41.3 41.0 41.8 41.6 41.7 42.2 41.7 41.9 42.0 41.8 41.7 41.7 41.7 41.4 41.1 39.1 41.9 41.1 41.3 41.1 41.8 41.1 41.6 41.3 39.8 41.2 41.3 42.0 41.5 41.5 41.8 41.5 41.3 41.9 41.3 41.4 42.1

0.01 0.01 0.01 0.03 0.02 0.02 0.01 0.02 0.02 0.11 0.09 0.04 0.02 0.07 0.07 0.06 0.05 0.15 0.04 0.15 0.13 0.15 0.26 0.31 0.12 0.13 0.14 0.11 0.17 0.02 0.04 0.04 0.05 0.03 0.06 0.04 0.05 0.04 0.03

55.1 55.3 55.3 55.2 55.3 55.1 55.7 55.4 55.4 55.3 55.5 55.0 55.1 55.4 54.9 54.3 54.2 52.6 55.1 54.8 54.9 54.4 55.0 54.9 55.1 54.7 53.0 55.3 55.5 56.3 55.2 55.7 55.3 55.2 54.9 55.2 55.6 55.0 55.4

0.04 0.01 0.01 0.02 0.07 0.02 0.00 0.07 0.07 0.02 0.06 0.02 0.02 0.03 0.07 0.00 0.05 0.00 0.03 0.08 0.04 0.09 0.08 0.12 0.02 0.02 0.08 0.05 0.05 0 0.06 0 0.06 0 0.06 0 0.03 0 0.01

100.6 100.5 101.0 99.9 100.8 99.9 101.1 101.1 100.7 101.6 102.2 100.6 101.0 101.8 100.9 100.1 99.5 97.1 100.9 99.5 100.0 99.8 101.0 100.1 100.1 100.0 96.9 100.2 101.2 100.8 99.1 99.5 99.2 98.5 98.6 99.3 99.3 98.9 99.8

et al., 2012). The detection limit of most elements analysed are from 0.01 to 0.1 ppm, except for Gd and Sm (0.3 ppm) (Pan et al., 2016). Detailed analytical descriptions are shown in Liu et al. (2008). 4. Results 4.1. EPMA

Fig. 4. Diagram showing concentrations of F (wt.%) versus Cl (wt.%) of apatite samples from the granodiorites in the SAP. Data for the Tongling (TL) apatite samples (literature) are from Xie et al. (2018).

The EPMA data of the apatite samples from the SAP granodiorites are shown in Table 2. The apatite analyzed samples show high F (2.69e4.13 wt.%) and low Cl (0.01e0.31wt.%) contents (Fig. 4, Table 2), and belong to fluorapatite. The apatite Cl contents are 0.01e0.03 wt.% (avg. 0.02 wt.%, n ¼ 9), 0.02e0.15 wt.% (avg. 0.07 wt.%, n ¼ 10), 0.11e0.31 wt.% (avg. 0.17 wt.%, n ¼ 10), and 0.02e0.06 wt.% (avg. 0.04 wt.%, n ¼ 10) from the LQ, JD, QY and PL granodiorite samples, respectively. The MnO contents of these apatite samples from the LQ, JD, QY and PL

Please cite this article as: Qian, L et al., The Late Mesozoic granodiorite and polymetallic mineralization in southern Anhui Province, China: A perspective from apatite geochemistry, Solid Earth Sciences, https://doi.org/10.1016/j.sesci.2019.11.006

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Ba

Th

U

Ta

Nb

Pb

Sr

Zr

Hf

Y

Ga

MnO

La

Ce

Pr

Nd

Sm

Eu

Gd

Tb

Dy

Ho

Er

Tm

Yb

Lu

0.08 0.53 0.11 0.22 0 0.33 0 0 0.6 0 0.15 0.11 0 0.21 0.44 0.63 0.55 0.09 0 0 0.2 0.26 0 0.75 0.28 0.35 1.8 0.08 0 0 0.36 0.25 0 0 0 0.12 0 0 0.31 0 0 0.17 0 0 0.0000

0.3 0.39 0.2 0.43 0.07 0.36 0.05 0.18 0.15 0.84 0.25 0.02 0.12 0.75 0.07 0.03 0.1 0.13 0.41 0.14 0.19 0.12 0.27 0 0.3 0.17 2.53 0.1 0.24 1.11 0.99 0.33 0.37 0 0.2 0 0.26 0.14 0.18 1.33 0 0.41 0.66 0.18 0.15

24.7 27.6 22.7 24.6 20.9 36.4 73.7 25.1 25.5 21.8 24.2 13.6 24.1 25.4 8.89 51.8 45.3 16.6 51.6 77.4 18.5 59.7 14.1 30.5 15.4 61.8 63.8 15 43.3 32.2 38.5 83.9 32.7 46.4 58.1 23.7 40.7 38.8 61.8 44.6 40.7 21.6 51.2 55.7 57.1

12.6 15.4 10.4 11.8 19.2 13.6 23.8 14.9 24 11.7 13.7 15.7 12.9 14.8 11.7 58.4 46.6 17.4 48.1 69.5 8.21 66.2 15.2 28.3 14.3 57.9 40.9 15.5 42.1 8.82 12.4 19.6 9.48 59.3 86 9.06 11.6 23.5 16.2 11.2 11.5 6.69 15 20.8 16.9

0.002 0 0.004 0.003 0 0 0 0 0 0.003 0.002 0 0.002 0.005 0 0 0.003 0 0.013 0.002 0.009 0 0.012 0.003 0.007 0 0.139 0.002 0.006 0.005 0.007 0 0.002 0.002 0.012 0 0 0.002 0.009 0.009 0 0 0.003 0.001 0.0000

0.006 0.016 0.036 0.006 0.021 0.018 0 0.015 0.054 0.045 0.028 0.008 0 0.014 0.015 0 0.009 0.004 0.003 0.076 0.005 0.015 0.029 0 0.013 0.031 0.327 0 0.049 0.023 0.022 0 0 0 0 0.028 0.031 0.041 0.053 0.041 0.008 0.015 0.031 0.038 0.029

5.53 6.00 5.68 5.51 5.57 6.56 6.45 5.10 5.67 4.27 5.88 5.17 6.31 5.79 3.32 3.72 3.74 3.21 3.61 4.27 3.68 4.74 3.12 3.21 3.25 4.26 5.53 3.27 4.30 2.39 2.02 2.88 2.63 1.16 1.72 1.43 1.93 1.62 1.84 2.78 2.26 1.67 2.44 2.14 4.47

255 197 214 203 147 192 198 189 134 308 156 126 275 243 151 155 139 152 144 150 145 143 155 156 149 149 151 155 153 346 377 204 253 172 157 182 196 144 137 359 277 432 326 167 327

0.42 0.65 0.77 0.53 0.43 2.89 1.87 0.43 0.23 0.44 0.35 0.17 0.46 0.38 0.04 0.35 0.49 0.11 0.42 0.65 0.24 0.52 0.15 0.27 0.21 0.51 2.05 0.12 0.3 1.23 0.75 1.86 1.76 0.28 0.41 1.19 0.9 0.52 0.92 2 1.74 0.7 1.62 1.13 0.90

0 0 0.018 0.028 0.018 0.01 0.049 0.004 0 0.024 0 0.019 0 0 0.032 0.005 0.033 0.013 0.015 0 0 0.057 0.016 0.004 0 0.016 0.088 0.022 0.018 0 0 0 0.025 0.031 0.031 0.006 0 0.028 0.005 0.03 0 0.022 0.041 0.009 0.019

335 355 321 302 248 410 230 318 266 304 279 181 282 336 913 1873 1297 1249 891 1266 965 1987 835 1455 745 1662 1890 634 1659 427 466 555 413 744 652 384 422 461 352 515 524 360 551 290 317

0.22 0.18 0.21 0.22 0.17 0.28 0.1 0.21 0.12 0.08 0.11 0 0.16 0.14 0.16 0.53 0.44 0.29 0.53 0.53 0.24 0.52 0.17 0.28 0.28 0.55 0.68 0.28 0.52 0.34 0.41 0.45 0.3 0.31 0.4 0.38 0.52 0.16 0.19 0.5 0.46 0.35 0.48 0.22 0.42

1237 1176 1209 1197 1099 1234 1147 1147 1121 1258 1097 1057 1232 1250 1231 1417 1516 1280 1441 1609 1711 1828 1416 1235 1475 1627 1613 1497 1667 1049 922 978 1168 362 521 664 876 713 734 1231 1041 1176 1066 851 1060

472 479 436 471 403 660 392 547 437 424 425 292 479 506 538 1629 1489 646 1801 2148 721 1543 915 599 913 1887 1078 829 1655 1485 1633 1458 1330 683 1319 1159 1201 1049 1182 1764 1641 1346 1581 984 1345

1170 1127 1067 1114 944 1542 918 1283 1001 1044 1000 619 1155 1232 1463 3832 3491 1764 3093 4755 1559 3660 1979 1524 2081 4189 2654 1874 3549 2828 3149 2858 2576 1622 2708 2310 2383 2072 2103 3409 3254 2556 3099 1717 2408

143 129 125 127 105 177 102 145 107 126 117 64.9 137 143 198 473 415 245 311 538 199 458 234 211 246 491 364 219 427 299 331 309 276 196 294 251 252 223 214 359 346 269 326 170 239

634 550 521 529 426 727 424 591 415 552 504 247 593 602 929 2100 1737 1165 1214 2140 919 1936 1009 1014 1029 2053 1672 920 1838 1120 1222 1212 1050 863 1176 983 994 883 846 1367 1315 1010 1245 653 873

120 97.7 96.9 91.9 68.7 127 73.8 104 69 105 93.9 40.6 111 105 221 467 348 286 233 373 225 428 214 269 204 421 421 180 407 167 181 193 162 169 191 148 152 140 123 200 191 143 189 94.1 124

19.7 18.1 14.5 14.5 10.4 21.4 11.5 17.1 11.5 18.8 14.7 7.15 17.6 16.7 18.6 28.5 24.8 21.6 13.2 49.4 10.3 37.8 14 35.2 17.5 31.8 18.7 16.5 23.8 21.7 22.6 22.8 17.8 19.5 19.6 17.5 16.7 15.6 15.2 25.8 24.2 18.8 24.8 14 22.5

108 95.7 88.3 80.9 63 114 68.9 91.8 62.8 91.5 88.8 37.1 96.4 96.2 219 456 325 296 234 328 242 407 204 269 187 400 423 174 397 132 141 158 126 164 166 116 119 119 104 156 151 107 148 78.1 97.1

12.2 11 9.9 9.65 6.71 13.5 7.73 10.2 7.13 10.9 9.83 4.53 11.1 11.3 28.6 61.5 41.9 38.8 29.4 39.8 32.8 54.8 26.3 38.9 23.6 52.3 59.8 21.3 53 15.9 17 19.3 15.3 21.6 20.4 14.1 14.7 14.6 12.3 18.8 18.3 12.6 18.5 9.2 10.8

61 55.9 51.2 49.4 35.8 66.4 37.2 52.6 35.2 54.5 50.4 23.3 53.3 54.7 153 334 223 213 156 207 175 307 137 220 125 284 332 110 292 83.4 89.7 102 79 123 112 74.6 79.2 80.9 64.7 102 99.4 68.1 103 50.4 54.8

11.3 11.1 9.58 9.45 7.11 12.5 7.21 10.3 7.3 10.2 9.17 4.71 9.66 10.6 29.6 65.5 44.3 41.5 30.6 40.8 33.7 62.1 26.7 42.4 24.4 54.9 65.8 21.1 57.2 15.5 16.7 19.5 14.8 24.7 22.5 13.8 15.2 16 12.7 18.8 18.6 13 19.5 9.9 10.6

28.4 28.9 24.8 24.2 19.7 33.5 18.2 26.2 21.3 25.5 22.9 13.7 22.7 26.8 72.2 166 114 103 74.7 108 81.6 165 67.1 116 60.6 140 168 50.1 147 39.3 40.4 50.9 36.7 67 60.3 34.4 37.9 42.6 31.7 46.6 48.3 32.3 50.4 27.9 27.0

3.74 3.95 3.44 3.48 2.8 4.5 2.5 3.4 3.27 3.19 3.04 2.17 2.91 3.62 8.94 20.6 14.3 13 8.65 14 9.3 22.1 7.89 16.4 7.77 17.6 20.8 5.94 18.5 5 5.29 6.55 4.8 9.1 8.3 4.45 5.18 5.57 4.06 6.06 6.1 4.15 6.64 3.75 3.49

24.5 28 24.6 22 20.9 31.1 18.4 23 24.4 20.7 21.2 16.2 17.8 25.7 57.2 126 90.8 79.8 50.6 96.5 49.2 140 46.7 118 46.3 109 121 37.8 108 30 31.1 39.6 28.1 62.1 53.7 27.7 30.3 37.6 25.6 37.3 37.5 25.1 42.3 25.5 23.6

4.17 5.04 4.5 4.14 4.36 5.38 3.3 3.79 5.24 3.31 3.83 3.62 2.79 4.38 8.67 18.3 14.3 11.7 8.15 16.6 6.36 20.1 7.18 19.7 7.44 16.4 16 6.16 15.6 4.45 4.14 6.17 3.98 10.6 8.8 4.09 4.4 6.29 4 5.28 5.14 3.49 5.89 4.15 3.75

MODEL

Rb

LQ-01 LQ-02 LQ-03 LQ-04 LQ-05 LQ-06 LQ-07 LQ-08 LQ-09 LQ-10 LQ-11 LQ-13 LQ-14 LQ-15 JD-01 JD-02 JD-03 JD-04 JD-05 JD-06 JD-07 JD-08 JD-09 JD-10 JD-11 JD-12 JD-13 JD-14 JD-15 QY-01 QY-02 QY-03 QY-04 QY-05 QY-06 QY-07 QY-08 QY-09 QY-10 QY-11 QY-12 QY-13 QY-14 QY-15 PL-1

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Please cite this article as: Qian, L et al., The Late Mesozoic granodiorite and polymetallic mineralization in southern Anhui Province, China: A perspective from apatite geochemistry, Solid Earth Sciences, https://doi.org/10.1016/j.sesci.2019.11.006

Table 3 LA-ICP-MS data of apatite from granodiorites in the southern Anhui province (ppm).

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7

granodiorites are 0.17e0.37 wt. %, 0.28e0.47 wt.%, 0.02e0.36 wt.% and 0.05e0.36 wt.%, respectively. 4.2. LA-ICP-MS

PL-2 PL-3 PL-4 PL-6 PL-7 PL-8 PL-9 PL-10 PL-11 PL-12 PL-13 PL-14 PL-15

0.67 0.42 0.38 0.25 0.0000 0.15 0.0000 0.0000 0.43 0.054 0.57 0.0000 0.0000

0.34 0.083 0.038 0.22 0.15 0.74 0.12 0.069 0.43 0.22 0.20 0.29 0.58

48.1 50.6 53.6 45.1 51.9 50.4 49.1 41.4 39.1 44.7 43.6 39.3 42.7

16.5 15.6 16.0 13.7 22.9 14.2 22.7 16.4 11.7 21.6 13.3 11.5 13.3

0.0000 0.0013 0.0000 0.0094 0.0019 0.0049 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0078

0.0000 0.019 0.0000 0.0000 0.036 0.0078 0.020 0.0000 0.019 0.032 0.0000 0.0000 0.0082

4.39 4.62 4.09 4.19 5.00 4.55 4.39 3.66 5.15 4.05 4.12 4.71 4.16

302 358 297 447 254 447 263 262 474 283 277 478 472

0.61 0.64 0.92 0.65 0.82 0.82 0.38 0.55 0.60 0.44 0.65 0.50 0.46

0.024 0.019 0.0052 0.0000 0.0000 0.0000 0.0000 0.018 0.018 0.0000 0.037 0.0034 0.0062

226 274 279 299 224 318 239 208 263 226 225 256 308

0.25 0.36 0.37 0.42 0.41 0.44 0.18 0.26 0.37 0.19 0.24 0.28 0.26

1016 1111 1103 1039 1064 1112 748 891 1245 986 839 1238 1048

1002 1118 1147 1317 1038 1367 769 868 1218 1043 1003 1201 1322

1777 2001 2029 2329 1773 2431 1509 1548 2103 1800 1746 2090 2312

163 197 199 229 163 242 156 150 198 165 162 202 226

568 740 741 833 571 895 609 547 705 565 576 728 819

77.8 108 103 115 74.6 129 92.6 75.6 98.2 73.3 76.8 105 115

15.9 15.4 17.1 20.4 11.2 22.8 12.4 12.9 19.0 13.1 15.1 18.4 21.1

61.4 90.2 86.8 93.8 60.6 98.4 75.3 64.1 79.0 60.1 63.6 80.7 90.5

7.11 9.89 9.28 10.8 6.69 11.3 8.27 6.83 8.74 6.77 6.94 9.12 10.3

36.0 49.4 48.7 54.7 35.4 57.5 42.1 34.3 44.7 34.6 35.9 46.7 53.8

7.39 9.42 9.52 10.2 6.79 10.7 8.25 7.03 8.81 6.87 7.37 8.69 10.1

19.8 23.6 24.7 25.9 18.4 28.2 20.2 18.6 22.8 19.3 20.0 22.7 26.2

2.73 2.94 3.06 3.39 2.61 3.58 2.70 2.52 3.12 2.71 2.78 3.22 3.47

19.5 17.9 20.1 22.2 17.3 22.4 16.6 16.4 20.1 19.5 19.6 18.2 23.0

3.28 2.99 3.27 3.48 3.22 3.53 2.78 2.98 3.26 3.47 3.64 2.96 3.40

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The LA-ICP-MS trace element compositions of the apatite samples from the SAP granodiorites are given in Table 3. The studied apatite samples have total Rare Earth Elements (REE) contents of 1376e3535 ppm (avg. 2508 ppm; n ¼ 14) in the LQ granodiorite, 3945e10854 ppm (avg. 6933 ppm; n ¼ 15) in the JD granodiorite, 3841e7516 ppm (avg. 5759 ppm; n ¼ 15) in the QY granodiorite, and 3324e5243 ppm (avg. 4310 ppm; n ¼ 14) in the PL granodiorite, respectively. The (La/Yb)N ratios in the LQ, JD, QY and PL apatite samples vary from 12.3 to 19.3, 3.64 to 25.5, 7.89 to 38.5, and 33.3 to 47.3, respectively. The chondrite-normalized REE patterns of the apatite samples from the SAP granodiorites, which consistently imitative those of the SAP granodiorites (Xie et al., 2017, 2019), exhibit right-inclined patterns and negative Eu anomalies (Fig. 5a). The apatite samples and their host rocks (the SAP granodiorites) show similarly higher LREE/HREE ratios ((La/Yb)N ¼ 3.64e47.3) and moderately negative Eu anomalies (dEu ¼ 0.13e0.70, avg. 0.48; dEu ¼ EuN/[(SmN) (NdN)]1/2) (Fig. 5a). On trace element pattern diagrams, the apatite samples show similar patterns, with notably negative Ba, Nb, Ta, Zr and Hf anomalies and positive Th and U anomalies (Fig. 5b). Most of the apatite samples have similar Sr contents (126e573 ppm), but they exhibit wide variations in Y compositions (136e1987 ppm) and low Sr/Y ratios (0.07e1.87) (Table 3). 5. Discussion 5.1. Adakite connection In general, Sr content of apatite decreases with the degree of magmatic fractionation, while Y shows the opposite trend (Belousova et al., 2002). Thus, apatites from granitic rocks have lower Sr and higher Y contents, while those of highfractionated pegmatites have the lowest Sr and highest Y contents (Belousova et al., 2002) (Fig. 6a). Plotted in classical discrimination, the studied apatite samples fall in the granitoids field, and mainly fall in the mafic rocks and iron ores field (Fig. 6a). Previous results collected the whole rock data show these studied intrusions in the SAP belong to Itype granites (Xie et al., 2017, 2019). Compared to apatites from mafic I-type granites, the apatites from S-type and felsic I-type granites have lower dEu (<0.2) values and La/Y ratios (<0.4), and higher chondrite-normalized (Sm/Nd)N (>0.8) values (Sha and Chappell, 1999). The apatites analyzed of the studied granodiorite samples in the SAP have high La/Y (0.41e4.69, avg. 2.43) and dEu (0.13e0.70, avg. 0.48), and low (Sm/Nd)N (0.34e0.81) values, and fall in the apatite field of mafic I-type granites (Fig. 6b, c), which indicates that the SAP magma was derived from oxided and metaluminous mafic I-type melt (Sha and Chappell, 1999). Ba and high field

Please cite this article as: Qian, L et al., The Late Mesozoic granodiorite and polymetallic mineralization in southern Anhui Province, China: A perspective from apatite geochemistry, Solid Earth Sciences, https://doi.org/10.1016/j.sesci.2019.11.006

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Fig. 5. Chondrite-normalized REE patterns of apatite (filled symbols) and host rock (open symbols) (a) and primitive mantle-normalized trace elements of apatite (b) from the granodiorites in the SAP. The chondrite REE and Primitive mantle standard values are from Sun and McDonough (1989). Data for LQ, JD and QY host rocks (granodiorites) are from Xie et al. (2017). Data for PL host rock (granodiorite) are from Xie et al. (2019).

Fig. 6. Geochemical diagrams of apatite samples from the SAP granodiorites. (a) Sr vs. Y (Belousova et al., 2002), (b) La/Y vs. Lu, (c) dEu vs. (Sm/Nd)N, (d) REE triangular diagram (Zhu et al., 2004). The fields of mafic, felsic I-type and S-type granites are after Sha and Chappell (1999). Note: M, mantle; M-C, mantle-crust; C, crust.

strength elements (e.g., Nb, Ta) have losses relative to Rb and Th, suggesting that crustal materials are involved in the magma components (Fig. 5b). In a rare earth element triangular diagram (Fig. 6d), Most of the studied apatite samples fall in the between M-C and M fields, indicating that these SAP intrusions were likely to be originated from mantlederived magmas mixing with the lower crustal components. The Tongling region (mainly CueAu deposits) is adjacent to the SAP (mainly CueMoeAueW deposits). Their metallogenic magmatic rocks have similar types and consistent formation age (Xie et al., 2017, 2018, 2019; Yan et al., 2017). And the formation ages of these deposits are also simultaneous

(Sun et al., 2003; Mao et al., 2006; Su et al., 2018). Therefore, this study chooses the ore-bearing magmatic rocks and their apatites from the Tongling region to make the comparison. The intermediate-acidic intrusive rocks with adakitic affinity, which are genetically related to CueAu mineralization (Ling et al., 2009; Sun et al., 2011, 2013, 2015), are widely distributed in the Tongling region, such as granodiorites in the Fenghuangshan and Jinkouling CueAu deposits (Fig. 7a) (Xie et al., 2018). According to the definition of Defant and Drummond (1990) and Drummond and Defant (1990), adakite is characterized by high Sr/Y and La/Yb ratios as well as low Y and Yb concentrations. Plotted in the Sr/Y vs. Y

Please cite this article as: Qian, L et al., The Late Mesozoic granodiorite and polymetallic mineralization in southern Anhui Province, China: A perspective from apatite geochemistry, Solid Earth Sciences, https://doi.org/10.1016/j.sesci.2019.11.006

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9

Fig. 7. Trace element discrimination plots for apatite (filled symbols) and host rock (open symbols) from the SAP granodiorites. (a) Sr/Y vs. Y of the SAP granodiorites (after Defant and Drummond, 1990), (b) dEu vs. Sr/Y of apatite samples. The apatite field of adakite from Tongling is after Xie et al. (2018). The apatite fields of adakite and non-adakite from Sanjiang are after Pan et al. (2016). Data for LQ, JD and QY host rocks (granodiorites) are from Xie et al. (2017). Data for PL host rock (granodiorite) are from Xie et al. (2019). Data for TL adakitic rocks are from Xie et al. (2018).

diagram (Defant and Drummond, 1990), the LQ, QY, JD and PL granodiorites closely related to CueMoeW mineralization mainly fall in the adakite field, with a trend towards typical arc rocks (Fig. 7a). The adakitic melts are considered to be generated at great lithospheric depth, where crystallization of plagioclase (the sink for Sr and Eu) is suppressed (Pan et al., 2016; Xu et al., 2014). Because the REE distribution coefficients of apatite do not vary significantly (Zhao, 2010), the REE partition patterns of the studied apatite samples tend to be similar with those of the whole rock compositions of the SAP granodiorites (Fig. 5a). In additional, Sr is highly compatible in apatite (Prowatke and Klemme, 2006), the relative REE, Y and Sr contents of apatite should be controlled by the melt composition (Li et al., 2018). The concentrations of REE, Sr and Y in apatite can offer a new way to distinguish the adakitic affinity even though the host rock subjected to later alteration and weathering, because of the strong resistance to alteration and metamorphism in apatite (Miles et al., 2014). Previous studies showed that apatites from adakites in the Sanjiang and Tongoing region had higher Sr/Y and dEu values compared to that of non-adakites (Pan et al., 2016; Xie et al., 2018). In dEu vs. Sr/Y diagram (Fig. 7b), apatite from adakitic

and non-adakitic rocks may be discriminated, as has been shown for the Tongling and Sanjiang adakites (Pan et al., 2016; Xie et al., 2018). As shown in the same diagram (Fig. 7b), the studied apatite samples from the LQ, QY and PL intrusions have high Sr/Y and dEu values, and plot in the adakite fields, to the exception of the JD apatite samples, thus matching the whole-rock compositions (Fig. 7a). This result reveals that Sr/Y and dEu values of apatite can be a good indicator to distinguish adakites from non-adakitic rocks (Pan et al., 2016). 5.2. Magmatic oxidation state The REE patterns (Zhu et al., 2004), Eu and Ce anomalies (Chu et al., 2009; Ding et al., 2015; Xie et al., 2018) and Mn contents of apatite (Miles et al., 2014) can reflect oxidation condition during the magma crystallization. The right-inclined distribution patterns and negative Eu anomalies (0.13e0.70) (Fig. 5a) of the studied apatite samples may be explained by either a Eu depletion in the hosting melt, or an oxidised state of the melt, or both. But that, owing to the demonstrably adakitic nature of the melt (Fig. 7), inheritance of a negative

Fig. 8. Plots of (a) dCe vs. dEu values and (b) logfO2 vs. T ( C) of apatite samples from the SAP granodiorites. MH: magnetite-hematite buffer, FMQ: fayalitemagnetite-quartz buffer, IW: iron-wustite buffer. Please cite this article as: Qian, L et al., The Late Mesozoic granodiorite and polymetallic mineralization in southern Anhui Province, China: A perspective from apatite geochemistry, Solid Earth Sciences, https://doi.org/10.1016/j.sesci.2019.11.006

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Fig. 9. Discrimination diagrams for apatite samples from the granodiorites in the SAP. The apatite fields of unmineralized rocks and ore deposits are from Mao et al. (2016). The unmineralized (grano) diorites and ore deposits division is after Mao et al. (2016).

anomaly being excluded, therefore, the negative Eu anomalies of the studied apatites are necessarily related to the oxidation state. As shown in Fig. 8a, the weakly negative dEu and dCe (dCe ¼ 2CeN/(LaN þ PrN)) relationship of these apatite samples from the SAP granodiorites also indicates that the SAP ore-bearing magmas were formed in high oxygen fugacity (fO2) environment. According to study on the relationship between the Mn content of apatite and oxygen fugacity, an empirical equation is obtained by Miles et al. (2014): logfO2 ¼
0.0022 (±0.0003)Mn (ppm)-9.75 (±0.46). The calculated logfO2 values of apatites studied using the Miles et al. (2014) formula range from
12.1 to
12.5 (average value of
12.3),
12.5 to
13.8 (average value of
13.1),
10.5 to
12.5 (average value of
11.7), and
11.4 to
12.5 (average value of
12.0) of the LQ, JD, QY and PL intrusions, respectively. The data points of apatite samples from the SAP granodiorites mainly fall within the field between MH and FMQ, indicating that their initial magma was under oxidising condition (Fig. 8b), which is in accord with the previous results of zircon and apatite from Cu-polymetallic deposit in the Tongling and Chizhou region (Xie et al., 2017, 2019). 5.3. Indicator of mineralization Previous researches have used apatite as an indicator for ore prospecting (Belousova et al., 2002; Ding et al., 2015; Mao et al., 2016; Miles et al., 2014; Pan et al., 2016; Xie et al., 2018). Trace element compositions of apatite have the potential for distinguishing various ore deposits and related rocks from unmineralized rocks (Mao et al., 2016). Fig. 9a compares the trace elements of apatite from the SAP ore-bearing granodiorites with those of apatite from various ore deposits (e.g., porphyry, skarn, epithermal, orogenic and IOCG deposits), and unmineralized rocks (Mao et al., 2016). The calculated DP1-1 and DP1-2 values of the studied apatite samples obtained using the method of Mao et al. (2016) range from 0.25 to 2.59 and
0.45 to 2.41 in the SAP granodiorites, completely fall within the field of ore deposits (Fig. 9a).

Nevertheless, few apatite samples from PL granodiorite fall at the intersection of the fields of ore deposits and unmineralized rocks (Fig. 9a). Because apatites from diorites and granodiorites have consistent negative Eu anomalies and elevated Cl contents compared with other apatite groups (Mao et al., 2016). Therefore, apatites from unmineralized diorites and granodiorites can be further discriminated from other apatites of ore deposits in terms of their dEu values and Cl contents (Fig. 9b). As shown in Fig. 9b, all of the apatites studied from the SAP granodiorites are obviously different from those of unmineralized (grano) diorites, and plot in the field of ore deposits, indicating that these SAP grandiorites were genetically related to CueMoeAu mineralization. And that apatites from porphyry Cu ± Mo ± Au deposits show high Mn contents (334e10,934 ppm) and variable, but generally clearly negative Eu anomalies (dEu ¼ 0.2e1.1, avg. 0.4) (Mao et al., 2016). The studied apatite samples have high Mn contents (208e1416 ppm) (Table 3) and obviously negative Eu anomalies (dEu ¼ 0.13e0.70, avg. 0.48) (Fig. 5a), similar with those of apatites from porphyry Cu ± Mo ± Au deposits. These results indicate that the Eu anomalies in apatite can be effective in discriminating the unmineralized (grano) diorites and porphyry Cu ± Mo ± Au deposits. F and Cl play an important role during magmatic evolution by depolymerizing the melt structure, enabling hydrothermal metal transport and ore deposition during degassing and fluid exsolution (Sun et al., 2007; Harlov, 2015; Jiang et al., 2018). Whole rock F and Cl contents may not directly reflect initial F and Cl abundances in the melt, but this can be traced by mineral enriched in F and Cl (e.g., apatite) (Prowatke and Klemme, 2006; Jiang et al., 2018). Here, data for apatite of the ore-bearing intrusive rocks from the Tongling CueAu deposits are cited in this study for comparison. As shown in Fig. 4, F contents of the studied apatite samples from the CueMoeAu ore-bearing intrusions in the SAP are consistent with those of apatite from the Tongling CueAu intrusions (Xie et al., 2018). However, Cl concentrations of apatite from the ore-bearing intrusions in the Tongling region have higher than those of apatite in the SAP granodiorites (Fig. 4),

Please cite this article as: Qian, L et al., The Late Mesozoic granodiorite and polymetallic mineralization in southern Anhui Province, China: A perspective from apatite geochemistry, Solid Earth Sciences, https://doi.org/10.1016/j.sesci.2019.11.006

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indicating that the Tongling magma is richer in Cl than the SAP magma, because they had different origins (Xie et al., 2017, 2018). Cl preferentially enters the liquid phase during slab dehydration (Sun et al., 2007), and Cl-rich fluids are crucial for the transportation of chalcophile elements (e.g., Cu and Au) because their solubility can notably increase with the increase of Cl content (Hezarkhani et al., 1999; Archibald et al., 2001). So, Cl is necessary for magmas to form the CueAu deposits (e.g., Tongling) (Sun et al., 2007; Xie et al., 2018). Moreover, the Cl contents of apatites from porphyry CueAu have higher than those of apatites from skarn W, porphyry CueMo and Mo deposits (Mao et al., 2016). Therefore, the difference in dissolved Cl concentration in orerelated intrusive rocks is one of the factors controlling the mineralization type that differs in the SAP and the Tongling region. 6. Conclusions The studied apatite samples from the SAP granodiorites with euhedral to hexagonal, show high F (2.69e4.13 wt. %) and low Cl (0.01e0.31wt. %) contents, and are fluorapatite. They have high La/Y (0.41e4.69, avg. 2.43) and dEu (0.13e0.70, avg. 0.48) values, and low (Sm/Nd)N values (0.34e0.81), showing the affinity of mafic I-type granites. Apatites have REE contents of 1376e10,854 ppm, coherent chondrite-normalized REE patterns characterized by rightinclined and negative Eu anomalies. They also have similar Sr contents (126e573 ppm), and low Sr/Y ratios (0.07e1.87). These results indicate that the Sr/Y and dEu values of apatite can be a good indicator to distinguish adakitic rocks from nonadakitic rocks. The REE distribution patterns, negative Eu anomalies, the negative dEu and dCe relationship, and high logfO2 values (
10.5 to
13.8) of apatites from the SAP granodiorites, indicate that these granodiorites had originated from mantlederived magmas mixing with the lower crustal components in high oxygen fugacity environment. The dEu values and Cl contents in apatite can be good indicators as discriminating the unmineralized rocks and ore deposit types. Acknowledgments This study is supported by the National Key R&D Program of China (No. 2016YFC0600404) and the National Natural Science Foundation of China (Grant No. 41373045). We would like to thank Editor-in-Chief, Prof. W.D. Sun, and two anonymous reviewers for their comments that improved the quality of manuscript. References Archibald, S.M., Migdisov, A.A., Williams-Jones, A.E., 2001. The stability of Au-chloride complexes in water vapor at elevated temperatures and pressures. Geochem. Cosmochim. Acta 65 (23), 4413e4423.

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Please cite this article as: Qian, L et al., The Late Mesozoic granodiorite and polymetallic mineralization in southern Anhui Province, China: A perspective from apatite geochemistry, Solid Earth Sciences, https://doi.org/10.1016/j.sesci.2019.11.006

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Please cite this article as: Qian, L et al., The Late Mesozoic granodiorite and polymetallic mineralization in southern Anhui Province, China: A perspective from apatite geochemistry, Solid Earth Sciences, https://doi.org/10.1016/j.sesci.2019.11.006