Subsolidus phase relations in the system Zr-Fe-Ti-O in equilibrium with metallic iron. Implications for lunar petrology     

Dominique Lattard 《Contributions to Mineralogy and Petrology》1987,97(2):264-278

An experimental study of the system Zr-Fe-Ti-O in equilibrium with metallic iron has been conducted at atmospheric pressure and in the temperature range 950–1300° C, with the purpose of modelling sub-solidus relations between Zr-bearing Fe-Ti oxide phases in lunar rocks. The phase relations are governed by the coexistence of the Fe-Ti oxides with ZrO₂ at temperatures below 1247° C, but with the new cubic ZFT phase at higher temperatures. ZFT, approximately Zr Fe Ti O₅, is probably related to the so-called stabilized cubic zirconia and could represent a synthetic equivalent of some lunar Zr-Fe-Ti rich oxide minerals.The zirconium contents in all Fe-, Ti and Fe-Ti-oxide phases increase with increasing temperature. At each temperature, Zr is incorporated preferentially in the Ti-oxide (up to 11 wt% ZrO₂), followed by ferropseudobrookite (up to 6 wt% ZrO₂), ilmenite (max. 4 wt%) and wüstite (max. 2.5 wt%). Ulvöspinel coexisting with ilmenite (+Fe⁰+ ZrO₂ and/or ZFT) always contains less than 1.2 wt% ZrO₂, whereas the same mineral in assemblage with wüstite-ZrO₂-Fe⁰ displays even higher ZrO₂ contents than ilmenite (above 4 wt%). Considering that the values determined here in the synthetic parageneses represent saturation concentrations at high temperatures in a simple model system, the ZrO₂ concentrations in the corresponding lunar minerals should generally be significantly lower. This is realized, except for the so-called Cr-Zr-Ca armalcolites which display ZrO₂ contents in the range 3.5–7 wt% and are thus probably related rather to Zr-rich oxide minerals than to armalcolite itself.  相似文献   

Geochemistry of the Tenryu Canyon deep-sea fan biological community (Kaiko)     

Dominique Dron  Jacques Boulgue  Asahiko Taira  Claude Rangin 《Earth and Planetary Science Letters》1987,83(1-4)

The Tenryu Canyon deep-sea fan biological community is characterized by both reduced and oxidized sediments in the immediate vicinity of the pore water vents. The upper sediments in contact with the clams are reduced, the organic matter is enriched in sulfur, and inorganic sulfides (Fe, Cu, Zn) are forming. Towards the outer fringes of the communities the sediment is oxidized and metals generally associated with ferro-manganese oxides are concentrated. Several metals, Cd, Pb, Mo show distributions which are strongly influenced by the metabolism of the clam colony. Comparison of water and sediment geochemistry leads to the conclusion that there should be a downward flux of oxygenated seawater on the boundaries of the colony and an upward flux of chemically more reduced deep pore water at the location of the colony. Trace metals anomalies as well asδ¹⁵N anomalies of organic matter may be useful to prospect for extinct venting areas in ancient subduction zones.  相似文献   

Comment on “a test of annual resolution in stalagmites using tree rings”     

Andy Baker  Dominique Genty 《Quaternary Research》2003,59(3):476-478

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A New Method for C ^k -Surface Approximation from a Set of Curves, with Application to Ship Track Data in the Marianas Trench     

Dominique Apprato  Christian Gout  Dimitri Komatitsch 《Mathematical Geology》2002,34(7):831-843

We introduce a surface approximation technique to address the problem of fitting a surface to a given set of curves. The originality of the method lies in its ability to take into account the continuous aspect of the data, and also in the possibility to arbitrarily select the regularity (C⁰, C¹, or higher) of the approximant obtained. We demonstrate the efficiency of the approach by constructing a bathymetry map of the Marianas trench based upon a set of SONAR (SOnic Navigation And Ranging) bathymetry ship track data.  相似文献   

A New Method for C k -Surface Approximation from a Set of Curves,with Application to Ship Track Data in the Marianas Trench     

Apprato  Dominique  Gout  Christian  Komatitsch  Dimitri 《Mathematical Geosciences》2002,34(7):831-843

We introduce a surface approximation technique to address the problem of fitting a surface to a given set of curves. The originality of the method lies in its ability to take into account the continuous aspect of the data, and also in the possibility to arbitrarily select the regularity (C⁰, C¹, or higher) of the approximant obtained. We demonstrate the efficiency of the approach by constructing a bathymetry map of the Marianas trench based upon a set of SONAR (SOnic Navigation And Ranging) bathymetry ship track data.  相似文献   

Distribution d'un élément trace (Cr) dans un sol développé sur roches métamorphiques : variabilité à l'échelle d'un versantDistribution of chromium in soils developed into metamorphic rocks: variability at the hillslope scale     

Sébastien Salvador-Blanes  Sophie Cornu  Dominique King 《Comptes Rendus Geoscience》2002,334(1):51-58

The influence of pedogenetic factors onto spatial variability of chromium in soil surface horizon was studied in a metamorphic area (Massif Central, France) at the hillside scale. A grid survey was performed. Surface soil horizons were sampled at each point and analysed in Cr. Results show the determinant influence of the rock type on Cr content distribution along the slope. However, surface horizons of these soils exhibit a lower Cr content heterogeneity than the deeper horizons. This was explained by soils' material erosion and deposition along the slope. Tillage and hedges also influence the Cr distribution in surface horizon along the slope. To cite this article: S. Salvador-Blanes et al., C. R. Geoscience 334 (2002) 51–58  相似文献   

Smooth Particle Lensing     

Dominique Aubert  Adam Amara  R. Benton Metcalf 《Monthly notices of the Royal Astronomical Society》2007,376(1):113-124

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Incorporating variable source area hydrology into a curve-number-based watershed model     

Elliot M. Schneiderman  Tammo S. Steenhuis  Dominique J. Thongs  Zachary M. Easton  Mark S. Zion  Andrew L. Neal  Guillermo F. Mendoza  M. Todd Walter 《水文研究》2007,21(25):3420-3430

Many water quality models use some form of the curve number (CN) equation developed by the Soil Conservation Service (SCS; U.S. Depart of Agriculture) to predict storm runoff from watersheds based on an infiltration-excess response to rainfall. However, in humid, well-vegetated areas with shallow soils, such as in the northeastern USA, the predominant runoff generating mechanism is saturation-excess on variable source areas (VSAs). We reconceptualized the SCS–CN equation for VSAs, and incorporated it into the General Watershed Loading Function (GWLF) model. The new version of GWLF, named the Variable Source Loading Function (VSLF) model, simulates the watershed runoff response to rainfall using the standard SCS–CN equation, but spatially distributes the runoff response according to a soil wetness index. We spatially validated VSLF runoff predictions and compared VSLF to GWLF for a subwatershed of the New York City Water Supply System. The spatial distribution of runoff from VSLF is more physically realistic than the estimates from GWLF. This has important consequences for water quality modeling, and for the use of models to evaluate and guide watershed management, because correctly predicting the coincidence of runoff generation and pollutant sources is critical to simulating non-point source (NPS) pollution transported by runoff. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

伊犁北部博罗霍努岩体年代学和地球化学研究及其大地构造意义   总被引：3，自引：8，他引：3  

王博  舒良树Dominique CLUZEL Michel FAURE Jacques CHARVET 《岩石学报》2007,23(8):1885-1900

博罗霍努岩体是发育在新疆伊犁北部的一个大型海西期花岗岩体,总体沿近 SE—NW 向分布,出露面积逾2000km~2。该岩体主要包括三类花岗岩:灰黑色辉石闪长岩、浅色黑云母花岗岩和紫红色黑云母钾长花岗岩。锆石 U—Pb La-ICP-MS 定年表明,辉石闪长岩的年龄为301±7Ma,黑云母花岗岩的年龄范围为294±7～285±7Ma,而黑云母钾长花岗岩则形成于280±5～266±6Ma。岩石地球化学分析显示,黑云母花岗岩和钾长花岗岩以准铝或弱过铝Ⅰ型花岗岩为主,个别属于弱过铝 S 型花岗岩。在微量元素方面,这些花岗岩均富集轻稀土而亏损重稀土,但来自两个剖面的花岗岩具有不同的稀土元素配分模式,可能代表它们的岩浆源区有所不同,因此需要进一步对这些花岗岩进行同位素地质学研究。相对于洋脊花岗岩而言,博罗霍努岩体的花岗岩明显富集 K,Rb,Ba 和 Th,同时,显著亏损 Nb,Ta,Y 和 Yh。以上地球化学特征及微量元素判别图表明,这些花岗岩类形成于俯冲有关的火山岛弧环境。结合伊犁及邻区岩浆岩的特征及其时代,可以认为博罗霍努岩体的形成与天山北部洋壳向南的俯冲造山作用有关。西天山北部俯冲造山作用最终在中二叠世结束,并在中一晚二叠世进入陆内造山和伸展拉张阶段。  相似文献   

U–Pb zircon dating of post-obduction volcanic-arc granitoids and a granulite-facies xenolith from New Caledonia. Inference on Southwest Pacific geodynamic models     

Jean-Louis Paquette  Dominique Cluzel 《International Journal of Earth Sciences》2007,96(4):613-622

In New Caledonia, the occurrence of one of the World’s largest and best-exposed subduction/obduction complex is a key point for the understanding of the geodynamic evolution of the whole Southwest Pacific region. Within the ophiolite, pre-and post-obduction granitoids intrude the ultramafic allochthon and provide new time constraints for the understanding of obduction processes. At 27.4 Ma, a new East-dipping subduction generated the active margin magmatism along the western coast of the island (Saint-Louis massif). At 24.3 Ma, the eastward shift of the magma activity and slightly different geochemical features (Koum-Borindi massif) was either related to the older slab break-off; or alternatively, due to the eastward migration of the mantle wedge following the collision of the eastern margin of the Low Howe rise. Finally, the occurrence of a granulite-facies xenolith in the Koum-Borindi massif with comparable 24.5 Ma U–Pb zircon age and isotopic features (initial ε_Nd = 5.1) suggests that these evolved magmas were generated within the lithospheric mantle beneath a continental crust of normal thickness. Geochronological evidence for continuous convergence during the Oligocene infers an East-dipping Eocene-Oligocene subduction/obduction system to have existed in the Southwest Pacific from the d’Entrecasteaux zone to the North Island of New Zealand.  相似文献