热液矿床成矿作用研究新途径:数值模拟          下载免费PDF全文

袁峰  李晓晖  胡训宇  李跃  贾蔡  Ord Alison  张明明  戴文强  李贺 《地质科学》2019,54(3):678-690

热液矿床是最具有工业价值的矿床类型之一,传统矿床学研究在成岩成矿作用、成矿机制和成矿规律等方面已有丰硕成果,但仍存在一些尚无法有效回答的科学问题。近年来,数值模拟方法逐步应用于热液矿床的研究,已成为成矿过程定量研究的新手段。本文系统总结了近年来热液矿床成矿过程数值模拟研究的成果和进展,并对存在问题和发展趋势进行了分析和展望,以期进一步推动这一交叉学科领域的研究。  相似文献   

Effect of water on the fluorine and chlorine partitioning behavior between olivine and silicate melt     

Bastian?JoachimEmail authorView author&#;s OrcID profile  André?Stechern  Thomas?Ludwig  Jürgen?Konzett  Alison?Pawley  Lorraine?Ruzié-Hamilton  Patricia?L.?Clay  Ray?Burgess  Christopher?J.?Ballentine 《Contributions to Mineralogy and Petrology》2017,172(4):15

Halogens show a range from moderate (F) to highly (Cl, Br, I) volatile and incompatible behavior, which makes them excellent tracers for volatile transport processes in the Earth’s mantle. Experimentally determined fluorine and chlorine partitioning data between mantle minerals and silicate melt enable us to estimate Mid Ocean Ridge Basalt (MORB) and Ocean Island Basalt (OIB) source region concentrations for these elements. This study investigates the effect of varying small amounts of water on the fluorine and chlorine partitioning behavior at 1280?°C and 0.3 GPa between olivine and silicate melt in the Fe-free CMAS+F–Cl–Br–I–H₂O model system. Results show that, within the uncertainty of the analyses, water has no effect on the chlorine partitioning behavior for bulk water contents ranging from 0.03 (2) wt% H₂O (D_Cl ^ol/melt = 1.6?±?0.9 × 10^?4) to 0.33 (6) wt% H₂O (D_Cl ^ol/melt = 2.2?±?1.1 × 10^?4). Consequently, with the effect of pressure being negligible in the uppermost mantle (Joachim et al. Chem Geol 416:65–78, 2015), temperature is the only parameter that needs to be considered for the determination of chlorine partition coefficients between olivine and melt at least in the simplified iron-free CMAS+F–Cl–Br–I–H₂O system. In contrast, the fluorine partition coefficient increases linearly in this range and may be described at 1280?°C and 0.3 GPa with (R ²?=?0.99): \(D_{F}^{\text{ol/melt}}\ =\ 3.6\pm 0.4\ \times \ {{10}^{-3}}\ \times \ {{X}_{{{\text{H}}_{\text{2}}}\text{O}}}\left( \text{wt }\!\!\%\!\!\text{ } \right)\ +\ 6\ \pm \ 0.4\times \,{{10}^{-4}}\). The observed fluorine partitioning behavior supports the theory suggested by Crépisson et al. (Earth Planet Sci Lett 390:287–295, 2014) that fluorine and water are incorporated as clumped OH/F defects in the olivine structure. Results of this study further suggest that fluorine concentration estimates in OIB source regions are at least 10% lower than previously expected (Joachim et al. Chem Geol 416:65–78, 2015), implying that consideration of the effect of water on the fluorine partitioning behavior between Earth’s mantle minerals and silicate melt is vital for a correct estimation of fluorine abundances in OIB source regions. Estimates for MORB source fluorine concentrations as well as chlorine abundances in both mantle source regions are within uncertainty not affected by the presence of water.  相似文献   

New 40Ar/39Ar constraints for the “Grande Nappe”: The largest rhyolitic eruption from the Mont-Dore Massif (French Massif Central)     

Sébastien Nomade  Jean-François Pastre  Alison Pereira  Alexandra Courtin-Nomade  Vincent Scao 《Comptes Rendus Geoscience》2017,349(2):71-80

Since the 1960s, an early explosive activity in the Mont-Dore Massif is associated with a major pyroclastic rhyolitic eruption (5–7 km³) known as the “Grande Nappe” (GN). This event, linked to the formation of a 6-km-diameter cryptic caldera named “Haute Dordogne”, was before our investigation dated by ⁴⁰Ar/³⁹Ar at 3.07 ± 0.04 Ma. Our new single-crystal laser fusion ⁴⁰Ar/³⁹Ar dates obtained on two outcrops of the GN (Rochefort-Montagne and Ludières) questioned several hypotheses made concerning this “landmark” event of the Mont-Dore Massif history. We demonstrate that: (1) the GN rhyolitic eruption has occurred much later than previously estimated (i.e. 2.77 ± 0.02–0.07 Ma full external uncertainties); (2) the correlation made between the Vendeix rhyolitic complexes (intra-caldera position) dated back to 2.74 ± 0.04 Ma and the GN is proposed; (3) xenocryst contamination could be very high (i.e. 70% for the Rochefort-Montagne GN outcrop) and explains the noticeable older age obtained previously; (4) a link between the GN eruption and the formation of a caldera is questionable; the hypothesis of a northward-oriented blast channeled eastward toward the paleo-Allier River is thus proposed.  相似文献   

Monitoring viscosity changes from time‐lapse seismic attenuation: case study from a heavy oil reservoir          下载免费PDF全文

Andrey H. Shabelansky  Alison Malcolm  Michael Fehler 《Geophysical Prospecting》2015,63(5):1070-1085

Heating heavy oil reservoirs is a common method for reducing the high viscosity of heavy oil and thus increasing the recovery factor. Monitoring of these viscosity changes in the reservoir is essential for delineating the heated region and controlling production. In this study, we present an approach for estimating viscosity changes in a heavy oil reservoir. The approach consists of three steps: measuring seismic wave attenuation between reflections from above and below the reservoir, constructing time‐lapse Q and Q^?1 factor maps, and interpreting these maps using Kelvin–Voigt and Maxwell viscoelastic models. We use a 4D relative spectrum method to measure changes in attenuation. The method is tested with synthetic seismic data that are noise free and data with additive Gaussian noise to show the robustness and the accuracy of the estimates of the Q‐factor. The results of the application of the method to a field data set exhibit alignment of high attenuation zones along the steam‐injection wells, and indicate that temperature dependent viscosity changes in the heavy oil reservoir can be explained by the Kelvin–Voigt model.  相似文献