Oxygen fugacity and porphyry mineralization: A zircon perspective of Dexing porphyry Cu deposit, China
Oxygen fugacity and porphyry mineralization: A zircon perspective of Dexing porphyry Cu deposit, China
复制标题
氧逸度与斑岩矿化：中国德兴斑岩铜矿床的锆石透视
DOI：
10.1016/j.gca.2017.03.013
复制
发表时间：
2017-06
影响因子：
5
通讯作者：
Wu Kai
中科院分区：
文献类型：
--
作者：
Zhang Chan-chan;Sun Wei-dong;Wang Jin-tuan;Zhang Li-peng;Sun Sai-jun;Wu Kai
氧逸度（fO2）是控制斑岩型铜矿形成的关键因素。斑岩型铜矿通常是氧化的，但斑岩岩浆何时以及如何获得高氧逸度特征，以及氧逸度如何控制斑岩矿化仍然不清楚。为探讨斑岩型铜矿高氧逸度的成因，测定了德兴斑岩型铜矿岩浆和继承锆石的微量元素组成和U-Pb年龄，计算了锆石的Ce4+/Ce3+，估算了母岩浆的氧逸度。中侏罗世（~ 170 Ma）岩浆锆石Ce4+/Ce3+比值较高（平均550），而继承锆石（200 ~ 880 Ma） Ce4+/Ce3+比值较低（平均263）。这一关系表明，德兴斑岩岩浆在侏罗纪岩浆锆石结晶（estimatedfO2： ΔFMQ + 0.7（±1.3）- ΔFMQ + 1.9（±1.3））时发生了高度氧化，不能像之前提出的那样归因于新元古代弧壳的部分熔融（estimatedfO2： ΔFMQ−2.4（±1.1）- ΔFMQ + 0.7（±1.2））。相反，这些岩浆的高fo2 （ΔFMQ + 1.5）是最新岩浆活动的主要特征。在fo2 > ΔFMQ + 1.5中，主要是硫酸盐而不是硫化物。一般来说，Cu和其他亲铜元素的行为受硫化物控制，而硫的形态受氧逸度控制。先前的模拟结果表明，在高氧逸度条件下（即使在>ΔFMQ + 1.5），地幔橄榄岩的部分熔融也不能形成富铜岩浆，这合理地解释了正常弧岩中缺乏斑岩型铜矿床的原因。这是因为地幔橄榄岩的铜、硫含量较低。模拟结果表明，在氧逸度高于ΔFMQ + 1.5的条件下，俯冲洋壳的部分熔融有利于产生铜含量足够高的斑岩原生岩浆，有利于斑岩成矿，这也解释了斑岩型铜矿床与具有绿质亲缘关系的氧化岩浆之间的密切关系。
Oxygen fugacity (fO2) is a key factor that controls the formation of porphyry Cu deposits. Porphyry Cu deposits are typically oxidized, but when and how porphyry magmas gain their high oxygen fugacity signatures, and how oxygen fugacity controls porphyry mineralization, remains obscure. To trace the origin of the high oxygen fugacity in porphyry Cu deposits, we determined trace element compositions and U-Pb ages of magmatic and inherited zircon from Dexing porphyry Cu deposit, calculated Ce4+/Ce3+of zircons and estimated the oxygen fugacity of their parental magmas. The Ce4+/Ce3+ratios of Middle Jurassic (∼170 Ma) magmatic zircons are high (550 on average), whereas the Ce4+/Ce3+ratios of inherited zircons (200–880 Ma) are much lower (263 on average). The relationship suggests that the Dexing porphyry magma was highly oxidized when the Jurassic magmatic zircons crystallized (estimatedfO2: ΔFMQ + 0.7 (±1.3) – ΔFMQ + 1.9 (±1.3)), which cannot be attributed to partial melting of the Neoproterozoic arc crust (estimatedfO2: ΔFMQ − 2.4 (±1.1) – ΔFMQ + 0.7 (±1.2)) as proposed previously. Instead, the highfO2(ΔFMQ + 1.5) of these magmas is a primary feature of the latest magmatism. Sulfate rather than sulfide is the dominant species atfO2> ΔFMQ + 1.5. In general, the behavior of Cu and other chalcophile elements is controlled by sulfide, while the sulfur speciation is controlled by oxygen fugacity. Previous modeling results show that partial melting of mantle peridotite under high oxygen fugacity (even at >ΔFMQ + 1.5) cannot form Cu-rich magmas, which plausibly explains the lack of porphyry Cu deposits in normal arc rocks. This is because mantle peridotite has low Cu and S contents. Our modeling shows that partial melting of subducted oceanic crust, under oxygen fugacities higher than ΔFMQ + 1.5, is favorable for producing primary magmas with Cu contents sufficiently high for porphyry mineralization, which plausibly explains the close relationship between porphyry Cu deposits and oxidized magmas with adakitic affinities.
登录
查看更多内容
影响因子：
3.9
作者：
C. Stern;M. A. Skewes;Alejandra Arévalo
通讯作者：
C. Stern;M. A. Skewes;Alejandra Arévalo
影响因子：
64.8
作者：
Gene Yogodzinski;Jonathan M. Lees;T. Churikova;F. Dorendorf;G. Wöerner;O. N. Volynets
通讯作者：
Gene Yogodzinski;Jonathan M. Lees;T. Churikova;F. Dorendorf;G. Wöerner;O. N. Volynets
影响因子：
5.3
作者：
Chiaradia, Massimo;Merino, Daniel;Spikings, Richard
通讯作者：
Spikings, Richard
中国东部前寒武纪与显生宙大陆下地壳水对比
影响因子：
3.9
作者：
Yang, Xiao-Zhi;Deloule, Etienne;Xia, Qun-Ke;Feng, Min;Fan, Qi-Cheng
通讯作者：
Fan, Qi-Cheng
影响因子：
4.6
作者：
Chelle-Michou C;Rottier B;Caricchi L;Simpson G
通讯作者：
Simpson G