同位素证据证明了在碰撞矿石系统中循环流体的重要性
Bo Xu1,2,3, Run-Sheng Yin4, Massimo Chiaradia5
1State Key Laboratory of Geological Processes and Mineral Resources, Frontiers Science Center for Deep-time Digital Earth, China University of Geosciences, Beijing 100083, China.
Science advances
|August 21, 2024
概括
(Hg) 同位素揭示了对大陆碰撞区铜沉积物起源的新见解. 阳性Hg同位素值表明地幔来源,挑战地的融化模型.
科学领域:
- 地质化学 地质化学
- 同位素地质学的同位素.
- 经济地质学 地质学
背景情况:
- 大陆碰撞石系统中流体和金属的来源尚不清楚.
- (Hg) 的同位素,特别是质量独立分离 (Δ199Hg),为挥发性和金属来源提供了潜在的标记物.
- 了解这些来源对于开发准确的金属遗传学模型至关重要.
研究的目的:
- 通过Hg同位素分析,研究大陆碰撞环境中的矿系统中的流体和金属的起源.
- 为了限制矿石形成流体的来源,在西藏南部的矿铜矿藏后沉积.
- 为了评估地幔与地来源在石起源中的作用.
主要方法:
- 在各种岩石类型中分析 (Hg) 同位素组成 (Δ199Hg).
- 从西藏南部采集矿石形成的孔岩,荒的岩石和地幔衍生的岩石岩石.
- 测量Hg同位素数据与潜在来源 (海水,海洋沉积物,地幔) 的已知同位素特征进行比较.
主要成果:
- 肥沃的孔岩和相关的黄岩岩呈现出主要是正的Δ199Hg值 (+0.25每毫米).
- 荒的岩石和一些岩石岩石在很大程度上显示负的Δ199Hg值 (-0.54到0.00每毫米).
- 阳性Δ199Hg值与海水和海洋沉积物的特征保持一致.
结论:
- 阳性 Δ199Hg 值表明,这些矿铜沉积物的最终流体来源是地幔石化层.
- 这种地幔来源很可能是由之前的海洋板块沉降造成的.
- 这些发现挑战了现有的模型,这些模型强调了在碰撞石系统中较低大陆地的融化.
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