Apatite and Zircon Geochemistry in Yao’an Alkali-Rich Porphyry Gold Deposit, Southwest China: Implications for Petrogenesis and Mineralization

The Yao’an gold deposit is located in the middle of the Jinshajiang-Ailaoshan alkali-rich metallogenic belt, and this belt hosts many porphyry-type Cu-Au-Mo deposits formed at 46–33 Ma. Yao’an porphyry gold-mineralization is intimately associated with biotite syenite porphyry, whereas the contempora...

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Autores principales:	Yulin Zheng, Changqing Zhang, Fudong Jia, Huan Liu, Qinggao Yan
Formato:	article
Lenguaje:	EN
Publicado:	MDPI AG 2021
Materias:	apatite zircon rare earth elements fluid exsolution oxygen fugacity Yao’an Mineralogy QE351-399.2
Acceso en línea:	https://doaj.org/article/90256ba7d5cd41d2a363f4b6f6998d13
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spelling	oai:doaj.org-article:90256ba7d5cd41d2a363f4b6f6998d132021-11-25T18:26:54ZApatite and Zircon Geochemistry in Yao’an Alkali-Rich Porphyry Gold Deposit, Southwest China: Implications for Petrogenesis and Mineralization10.3390/min111112932075-163Xhttps://doaj.org/article/90256ba7d5cd41d2a363f4b6f6998d132021-11-01T00:00:00Zhttps://www.mdpi.com/2075-163X/11/11/1293https://doaj.org/toc/2075-163XThe Yao’an gold deposit is located in the middle of the Jinshajiang-Ailaoshan alkali-rich metallogenic belt, and this belt hosts many porphyry-type Cu-Au-Mo deposits formed at 46–33 Ma. Yao’an porphyry gold-mineralization is intimately associated with biotite syenite porphyry, whereas the contemporaneous quartz syenite porphyry is barren. In this study, we compared the major and trace elements of apatite and zircon and isotopic compositions of zircon from the biotite syenite porphyry and quartz syenite porphyry, to explore their geochemical differences that may affect their mineralization potential. The results show that both porphyries were derived from the partial melting of the thickened lower crust, which has been modified by slab-derived fluids, but has different mineral crystallization sequences, magma fluid activities, and magma oxidation states, respectively. REE contents in apatite and zircon can be used to reveal the crystallization sequence of minerals. A rapid decrease of (La/Yb)<sub>N</sub> ratio in apatite from both porphyries may be caused by the crystallization of allanite. Large variation of Cl contents and negative correlation between F/Cl and (La/Yb)<sub>N</sub> in apatite from fertile porphyry indicate that it has experienced the exsolution of Cl-bearing hydrothermal fluid. Higher Y/Ho and lower Zr/Hf in zircon from fertile porphyry indicate a stronger fluid activity than barren porphyry. The high S, V, As contents, δEu, low δCe in apatite, as well as high Ce<sup>4+</sup>/Ce<sup>3+</sup> and log(<i>f</i>O<sub>2</sub>) estimated from zircon geochemistry from fertile porphyry, indicate high a oxidation state of fertile porphyry, similar to other fertile porphyries in this metallogenic belt. High fluid activity and fluid exsolution are conducive to the migration and enrichment of metal elements, which are very important for mineralization. High oxygen fugacity inhibits the precipitation of metal in the form of sulfide, thereby enhancing the mineralization potential of rock. Therefore, the exsolution of Cl-bearing hydrothermal fluid and high oxygen fugacity are the key factors promoting mineralization in Yao’an area.Yulin ZhengChangqing ZhangFudong JiaHuan LiuQinggao YanMDPI AGarticleapatitezirconrare earth elementsfluid exsolutionoxygen fugacityYao’anMineralogyQE351-399.2ENMinerals, Vol 11, Iss 1293, p 1293 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	apatite zircon rare earth elements fluid exsolution oxygen fugacity Yao’an Mineralogy QE351-399.2
spellingShingle	apatite zircon rare earth elements fluid exsolution oxygen fugacity Yao’an Mineralogy QE351-399.2 Yulin Zheng Changqing Zhang Fudong Jia Huan Liu Qinggao Yan Apatite and Zircon Geochemistry in Yao’an Alkali-Rich Porphyry Gold Deposit, Southwest China: Implications for Petrogenesis and Mineralization
description	The Yao’an gold deposit is located in the middle of the Jinshajiang-Ailaoshan alkali-rich metallogenic belt, and this belt hosts many porphyry-type Cu-Au-Mo deposits formed at 46–33 Ma. Yao’an porphyry gold-mineralization is intimately associated with biotite syenite porphyry, whereas the contemporaneous quartz syenite porphyry is barren. In this study, we compared the major and trace elements of apatite and zircon and isotopic compositions of zircon from the biotite syenite porphyry and quartz syenite porphyry, to explore their geochemical differences that may affect their mineralization potential. The results show that both porphyries were derived from the partial melting of the thickened lower crust, which has been modified by slab-derived fluids, but has different mineral crystallization sequences, magma fluid activities, and magma oxidation states, respectively. REE contents in apatite and zircon can be used to reveal the crystallization sequence of minerals. A rapid decrease of (La/Yb)<sub>N</sub> ratio in apatite from both porphyries may be caused by the crystallization of allanite. Large variation of Cl contents and negative correlation between F/Cl and (La/Yb)<sub>N</sub> in apatite from fertile porphyry indicate that it has experienced the exsolution of Cl-bearing hydrothermal fluid. Higher Y/Ho and lower Zr/Hf in zircon from fertile porphyry indicate a stronger fluid activity than barren porphyry. The high S, V, As contents, δEu, low δCe in apatite, as well as high Ce<sup>4+</sup>/Ce<sup>3+</sup> and log(<i>f</i>O<sub>2</sub>) estimated from zircon geochemistry from fertile porphyry, indicate high a oxidation state of fertile porphyry, similar to other fertile porphyries in this metallogenic belt. High fluid activity and fluid exsolution are conducive to the migration and enrichment of metal elements, which are very important for mineralization. High oxygen fugacity inhibits the precipitation of metal in the form of sulfide, thereby enhancing the mineralization potential of rock. Therefore, the exsolution of Cl-bearing hydrothermal fluid and high oxygen fugacity are the key factors promoting mineralization in Yao’an area.
format	article
author	Yulin Zheng Changqing Zhang Fudong Jia Huan Liu Qinggao Yan
author_facet	Yulin Zheng Changqing Zhang Fudong Jia Huan Liu Qinggao Yan
author_sort	Yulin Zheng
title	Apatite and Zircon Geochemistry in Yao’an Alkali-Rich Porphyry Gold Deposit, Southwest China: Implications for Petrogenesis and Mineralization
title_short	Apatite and Zircon Geochemistry in Yao’an Alkali-Rich Porphyry Gold Deposit, Southwest China: Implications for Petrogenesis and Mineralization
title_full	Apatite and Zircon Geochemistry in Yao’an Alkali-Rich Porphyry Gold Deposit, Southwest China: Implications for Petrogenesis and Mineralization
title_fullStr	Apatite and Zircon Geochemistry in Yao’an Alkali-Rich Porphyry Gold Deposit, Southwest China: Implications for Petrogenesis and Mineralization
title_full_unstemmed	Apatite and Zircon Geochemistry in Yao’an Alkali-Rich Porphyry Gold Deposit, Southwest China: Implications for Petrogenesis and Mineralization
title_sort	apatite and zircon geochemistry in yao’an alkali-rich porphyry gold deposit, southwest china: implications for petrogenesis and mineralization
publisher	MDPI AG
publishDate	2021
url	https://doaj.org/article/90256ba7d5cd41d2a363f4b6f6998d13
work_keys_str_mv	AT yulinzheng apatiteandzircongeochemistryinyaoanalkalirichporphyrygolddepositsouthwestchinaimplicationsforpetrogenesisandmineralization AT changqingzhang apatiteandzircongeochemistryinyaoanalkalirichporphyrygolddepositsouthwestchinaimplicationsforpetrogenesisandmineralization AT fudongjia apatiteandzircongeochemistryinyaoanalkalirichporphyrygolddepositsouthwestchinaimplicationsforpetrogenesisandmineralization AT huanliu apatiteandzircongeochemistryinyaoanalkalirichporphyrygolddepositsouthwestchinaimplicationsforpetrogenesisandmineralization AT qinggaoyan apatiteandzircongeochemistryinyaoanalkalirichporphyrygolddepositsouthwestchinaimplicationsforpetrogenesisandmineralization
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Apatite and Zircon Geochemistry in Yao’an Alkali-Rich Porphyry Gold Deposit, Southwest China: Implications for Petrogenesis and Mineralization

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