Dating of granite-related tin mineralisation at Quy Hop, Vietnam: Constraints from zircon and cassiterite U–Pb and muscovite 40Ar/39Ar geochronology
Dating of granite-related tin mineralisation at Quy Hop, Vietnam: Constraints from zircon and cassiterite U–Pb and muscovite 40Ar/39Ar geochronology
复制标题
越南归合花岗岩相关锡矿化年代测定：来自锆石和锡石 U-Pb 以及白云母 40Ar/39Ar 地质年代学的限制
DOI：
10.1016/j.oregeorev.2022.104785
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发表时间：
2022
影响因子：
3.3
通讯作者：
Yang Wu
中科院分区：
文献类型：
--
作者：
Dinh Cong Bui;Hua-Ning Qiu;Xuan Dac Ngo;Xiu-Juan Bai;Yang Wu
Quy Hop是越南中北部沿海省的一个重要锡矿区。出露的岩浆岩体包括晚渐新世-早中新世花岗岩类和中三叠世花岗质片麻岩。该地区的锡矿化在空间上与Ban Chieng杂岩的黑云母花岗岩有关。石英脉型锡矿和云英岩型锡矿分别产于奥陶系-志留系宋卡组的石英-绢云母-石墨片岩和晚渐新世班强杂岩的云英岩化花岗岩中。锡矿床和花岗质岩石缺乏准确的年代学资料，限制了我们对锡矿化与花岗岩类侵入体成因关系的认识。在这项研究中，花岗质锆石和白云母激光烧蚀和电感耦合等离子体质谱U-Pb和白云母40 Ar/39 Ar定年技术，以解决这一认识不足。从Ban Chieng获得的两个黑云母花岗岩样品的花岗质锆石U-Pb测年得到的交叉年龄为26.65 ± 0.33和23.89 ± 0.15 Ma，这里解释为代表性的岩浆侵位年龄。锡石U-Pb分析得到Suoi Bac石英脉矿石和Ban Ngoc云英岩矿石的207 Pb/206 Pb-238 U/206 Pb交点年龄分别为26.81 ± 1.92 Ma和23.23 ± 0.89 Ma。云英岩矿石的白云母40 Ar/39 Ar激光阶跃加热获得坪年龄为23.87 ± 0.14Ma，相应的逆等时线年龄为23.85 ± 0.16Ma。这些地质年代学结果强烈表明，锡矿化在贵合发生在26和23马之间的时期，因此，密切相关的晚古近纪花岗岩的班清复杂。新年龄数据的勘探意义相当大，表明黑云母花岗岩侵入体可能有利于整个Phu Hoat地体的锡矿化。
Quy Hop is an important tin mining district in the North Central Coast province of Vietnam. The exposed magmatic plutons include Late Oligocene – Early Miocene granitoid and Middle Triassic granitic gneiss. Tin mineralisation in the area is spatially associated with biotite granite of the Ban Chieng Complex. Quartz vein-type and greisen-type tin ores occur in quartz-sericite-graphite schist of the Ordovician-Silurian Song Ca Formation and the greisenised granite of the Late Oligocene Ban Chieng Complex, respectively. The lack of accurate geochronological dates for the tin deposits and spatially associated granitic rocks limits our understanding of the genetic relationship between tin mineralisation and granitoid intrusions. In this study, granitic zircon and cassiterite laser ablation and inductively coupled plasma mass spectrometry U–Pb and muscovite40Ar/39Ar dating techniques were applied to address this lack of understanding. Granitic zircon U–Pb dating of two biotite granite samples obtained from Ban Chieng yielded intersection ages of 26.65 ± 0.33 and 23.89 ± 0.15 Ma, interpreted here as representative igneous emplacement ages. Cassiterite U–Pb analyses yielded207Pb/206Pb–238U/206Pb intersection ages of 26.81 ± 1.92 Ma for the quartz vein ore from Suoi Bac and 23.23 ± 0.89 Ma for greisen ore from Ban Ngoc. Muscovite40Ar/39Ar laser step heating of the greisen ore yielded a plateau age of 23.87 ± 0.14 Ma and a corresponding inverse isochron age of 23.85 ± 0.16 Ma. These geochronological results strongly suggest that tin mineralisation at Quy Hop occurred in the period between 26 and 23 Ma and, therefore, is closely genetically related to the Late Palaeogene granites of the Ban Chieng Complex. The exploration implication of the new age data is considerable, indicating that biotite granite intrusions may be favourable for tin mineralisation across the entire Phu Hoat Terrane.