Ilvaite as a thermodynamic recorder of multistage retrograde alteration in large Galinge skarn Fe deposit, western China
Ilvaite as a thermodynamic recorder of multistage retrograde alteration in large Galinge skarn Fe deposit, western China
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伊尔瓦铁矿作为中国西部嘎林格大型矽卡岩铁矿床多期逆行蚀变的热力学记录器
DOI：
10.1007/s11771-019-4271-8
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发表时间：
2019-12
期刊：
影响因子：
--
通讯作者：
于淼
中科院分区：
文献类型：
--
作者：
于淼
研究了加林格矽卡岩矿床中含伊尔辉石的矽卡岩组合，确定了其物理化学形成条件。建立了一个设定压力为50 MPa （Pf=Ps=50 MPa）的热力学模型来跟踪矽卡岩的演化。岩石学证据表明，在早期逆行阶段（第1阶段）石榴石和磁铁矿被钛铁矿取代，结合热力学模型表明，蚀变可能发生在400-470°C，中等高fo2， ΔlgfO2（HM）范围为−4 ~−4.2。该模型基于岩浆角闪孔地压计计算的最大压力为50 MPa。钛铁矿与石英的持续分解形成放线石和磁铁矿发生在后期逆行阶段（第II阶段）。反应在400-440℃，中氧条件下进行（ΔlgfO2(HM):−4 ~−4.4）。在第三阶段，钛铁矿分解生成方解石、黄铁矿和亚铁放线石取决于XCO2，估计在0.005 ~ 0.05范围内，随着XCO2的增加，反应温度也会升高。在这些条件下，击穿发生在270-350°C和低fo2 （ΔlgfO2(HM)：高达−5.2）。从第一阶段到第三阶段连续演化的热力学模型完整地记录了逆行蚀变的条件，这与流体包裹体的测温印记不一致。因此，银辉石的岩石学和相关系是各种矽卡岩型矿床反应条件的有用指示物。
The ilvaite-bearing skarn associations in the Galinge skarn deposit were studied to determine their physicochemical formation conditions. A thermodynamic model setting pressure of 50 MPa (Pf=Ps=50 MPa) was set up to trace the skarn evolution. Petrographic evidence for replacement of garnet and magnetite by ilvaite in the early retrograde stage (Stage I) combined with thermodynamic modeling suggests that the alteration may have occurred at 400–470 °C under moderately highfO2with ΔlgfO2(HM) ranges from −4 to −4.2. The model is based on a maximum pressure of 50 MPa calculated from magmatic amphibole geobarometer. The continuous breakdown of ilvaite with quartz to form ferro-actinolite and magnetite occur in the late retrograde stage (Stage II). The reactions occurred at 400-440°C under moderatefO2(ΔlgfO2(HM): −4 to −4.4). In Stage III, the breakdown of ilvaite to form calcite, pyrite and ferroactinolite depends onXCO2which can be estimated to be in a range of 0.005 to 0.05, and the reaction would occur at higher temperatures with increasing XCO2. Under these conditions, the breakdown occurs at 270–350 °C and lowfO2(ΔlgfO2(HM): up to −5.2). The thermodynamic model for continuous evolution from Stage I to Stage III completely records the conditions of the retrograde alteration, which is inconsistent with the thermobarometry imprints of fluid inclusions. Therefore, the petrography and phase relations of ilvaite are useful indicators of reaction conditions in various skarn deposit types.
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影响因子：
0.7
作者：
L. I. Rogulina;O. Sveshnikova
通讯作者：
L. I. Rogulina;O. Sveshnikova
影响因子：
5.8
作者：
M. Franchini;L. Meinert;J. M. Vallés
通讯作者：
M. Franchini;L. Meinert;J. M. Vallés
影响因子：
5.8
作者：
L. Meinert
通讯作者：
L. Meinert
影响因子：
3.9
作者：
W. Gustafson
通讯作者：
W. Gustafson
DOI：
10.1007/978-94-011-3925-0
发表时间：
1999-11
期刊：
--
影响因子：
--
作者：
K. Misra
通讯作者：
K. Misra