Rapid formation of porphyry copper deposits evidenced by diffusion of oxygen and titanium in quartz
Rapid formation of porphyry copper deposits evidenced by diffusion of oxygen and titanium in quartz
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DOI：
10.1130/g40262.1
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发表时间：
2018-06
期刊：
影响因子：
5.8
通讯作者：
F. Cernuschi;J. Dilles;S. Grocke;J. Valley;K. Kitajima;F. Tepley
中科院分区：
文献类型：
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作者：
F. Cernuschi;J. Dilles;S. Grocke;J. Valley;K. Kitajima;F. Tepley
岩浆热液活动的寿命导致了大型和经济上可行的斑岩铜矿，但仍然缺乏描述。本文利用秘鲁Haquira东斑岩铜矿含Fe、Cu和Mo硫化物热液脉和斑岩脉石英中Ti和δ18O的扩散剖面，估算了岩浆-热液流体在700°C至<350°C范围内的流动持续时间。原位测量表明，所有脉状石英均以Ti （1 ~ 120ppm）为分带，而高温石英在450℃时δ18O = 10.7‰重新平衡。我们使用扩散模型来重现观测到的Ti和δ18O剖面，这些剖面提供了Haquira从700°C初始岩浆和流体注入到350°C以下冷却期间的75-170 ky的寿命估计。大部分Cu-Mo-Au矿石形成时间≤35ky，表明大规模、经济的斑岩型铜矿床可以快速形成。
The lifespan of magmatic-hydrothermal activity that results in large and economically viable porphyry copper deposits remains poorly described. Here, we estimate the duration of the magmatic-hydrothermal fluid flow at 700 °C to <350 °C using diffusion profiles of Ti and δ18O in quartz from Fe, Cu, and Mo sulfide-bearing hydrothermal veins and porphyry dikes at the Haquira East porphyry copper deposit, Peru. In situ measurements indicate all vein quartz is zoned in Ti (1–120 ppm), whereas high-temperature quartz has been re-equilibrated at 450 °C to δ18O = 10.7‰. We use diffusion modeling to reproduce the observed Ti and δ18O profiles, which provides lifespan estimates at Haquira of 75–170 k.y. for the period from initial magma and fluid injection at 700 °C to cooling below 350 °C. The bulk of the Cu-Mo-Au ore formed in ≤35 k.y., indicating that large-scale, economic porphyry copper deposits can form rapidly.