Tracking meteoric infiltration into a magmatic-hydrothermal system: A cathodoluminescence, oxygen isotope and trace element study of quartz from Mt. Leyshon, Australia
Tracking meteoric infiltration into a magmatic-hydrothermal system: A cathodoluminescence, oxygen isotope and trace element study of quartz from Mt. Leyshon, Australia
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DOI：
10.1016/j.chemgeo.2007.03.004
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发表时间：
2007-06-15
期刊：
影响因子：
3.9
通讯作者：
Yardley, Bruce W. D.
中科院分区：
文献类型：
--
作者：
Allan, Murray M.;Yardley, Bruce W. D.
热液石英的氧同位素和微量元素组成与扫描电子显微镜-阴极发光（SEM-CL）图像和流体包裹体性质相结合，以跟踪Mt. Leyshon An存款，澳大利亚。氧同位素和微量元素的数据收集平行穿越相同的石英部分，使用二次同位素质谱（西姆斯）和激光烧蚀电感耦合等离子体质谱（LA-ICP-MS），分别与SEM-CL图像分析前获得的岩相背景。在流体包裹体显微测温法所建议的280至650 ℃石英沉淀范围内，δ O-18（石英）从0.0至14.4%o变化，对应于宽范围的平衡δ O-18（流体）值，从-6.1至10.2%o（vs. V-SMOW）。三角洲O-18（石英）签名系统不同的SEM-CL石英代（内和样品之间），并可以与温度和流体成分的变化，但独立的代内振荡分区。与此相反，铝和锂的浓度与振荡石英的CL强度广泛相关，而它们的浓度是不可预测的密封裂缝和过度生长。B、Mg、Na、P、Cl、K、Ti、Mn、Fe、Ge和Sn的浓度与Al、Li和振荡CL特征无关，但Ti与石英沉淀温度相关。虽然没有发现δ O-18（石英）和微量元素浓度之间的系统相关性，但在低δ O-18（石英）（类似于0%o）和高Al（> 10，000 ppma）的狭窄过度生长中存在互补模式。这些石英带可能是在O-18贫化的大气降水侵入岩浆为主的Mt.莱申热液系统我们解释的最高铝浓度的结果，高石英沉淀率，引发减压的热液池。石英中氧同位素和微量元素模式的退耦表明：（1）在大多数情况下，温度和流体化学控制三角洲O-18（石英），（2）微量元素记录，特别是Al和Li，受到石英沉淀速率叠加效应的影响。(C)2007 Elsevier B. V.保留所有权利。
The oxygen isotope and trace element composition of hydrothermal quartz has been integrated with scanning electron microscope-cathodoluminescence (SEM-CL) images and fluid inclusion properties to track fluid sources and hydrothermal processes in the Mt. Leyshon An deposit, Australia. Oxygen isotope and trace element data were collected on parallel traverses across the same quartz sections, using secondary isotope mass spectrometry (SIMS) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), respectively, with SEM-CL images obtained before analysis for petrographic context. Over the 280 to 650 degrees C quartz precipitation range suggested by fluid inclusion microthermometry, delta O-18(quartz) varies from 0.0 to 14.4%o, corresponding to a wide range of equilibrium delta O-18(fluid) values, from-6.1 to 10.2%o (vs. V-SMOW). The delta O-18(quartz) signature varies systematically among distinct SEM-CL quartz generations (both within and between samples), and can be correlated with variations in temperature and fluid composition, but is independent of intra-generational oscillatory zoning. In contrast, Al and Li concentrations correlate broadly with CL intensity in oscillatory quartz, whereas their concentration is unpredictable in sealed fractures and overgrowths. Concentrations of B, Mg, Na, P, Cl, K, Ti, Mn, Fe, Ge, and Sn are independent of Al, Li, and oscillatory CL features, but Ti correlates with quartz precipitation temperature. Although no systematic correlation between delta O-18(quartz) and trace element concentrations was found, complementary patterns exist in narrow overgrowths of low delta O-18(quartz) (similar to 0%o) and high Al (> 10,000 ppma). These quartz zones likely formed during the incursion of O-18-depleted meteoric water into the magmatically-dominated Mt. Leyshon hydrothermal system. We interpret the highest Al concentrations as the result of high quartz precipitation rates, triggered by depressurisation of the hydrothermal cell. The decoupling of oxygen isotope and trace element patterns in quartz leads to the suggestion that (1) under most circumstances, temperature and fluid chemistry dominate delta O-18(quartz), and (2) the trace element record, and in particular Al and Li, is influenced by the superimposed effects of quartz precipitation rate. (C) 2007 Elsevier B.V. All rights reserved.