Episodic mineralization of hydrothermal illite in the Soultz-sous-Forêts granite (Upper Rhine Graben, France)

Episodic and localized illite mineralization is documented in the hydrothermally altered Soultz-sous-Forêts granite (Upper Rhine Graben, France). Separated grain-size fractions of altered granite and argillite vein samples contain mixtures of 2M₁ and 1M trans-vacant illite varieties. The platy pseudohexagonal 2M₁ illite phases dominate the vein fillings, whereas the 1M illite occurs largely as a fibrous pore-filling variety, which is particularly abundant in the granite matrix. Multiple phases of fluid injections into the granite body have resulted in different illite assemblages, each sample containing a mixture of polytype generations formed during different crystal growth events. On the basis of mineralogical and K–Ar isotopic constraints, the ages of these vein-mineralizing events are determined by plotting the K–Ar values of the various grain-size fractions against polytype abundance and the fitted volume-weighted crystallite thickness distributions. The results suggest a Permian age for the formation of the studied argillite veins, characterized by successive injections of hydrothermal fluids. Secondary episodes of illite crystallization occurred during Jurassic and Cretaceous (or even younger times) in both the veins and the granite matrix. There are indications that the polytype structure and composition of illite were strongly influenced by variations in fluid chemistry and the degree of fluid–rock interaction as the granite was progressively sealed during post-Variscan, episodic hydrothermal activity.     

320铀矿床成矿角砾岩成因新识

本文介绍在３２０铀矿床中首次发现的热液隐爆现象。提出该矿床中的成矿角砾岩是以构造岩成因为主、热液隐爆为辅的复成因认识。角砾岩中的晶洞是多成因的，其中以构造角砾岩成因晶洞为主，另可由热液隐爆、粗体生物化石溶失和脱落（印模）、古岩溶和现（近）代热泉水溶蚀、岩石中黄铁矿溶失等造成。推测硅化角砾岩的原岩为硅岩、炭质页岩和炭泥质生物屑灰岩。     

陕西穆家庄铜矿床地质地球化学特征及找矿标志

穆家庄铜矿床形成于柞水．山阳泥盆纪热水沉积盆地中受同生断裂控制的次级深水盆地中，矿体呈透镜状、似层状沿北西西向构造破碎带产出，是秦岭泥盆系中热水沉积一构造改造型的典型矿床之一。在总结矿区地质特征、地球化学特征的基础上，建立了综合找矿标志，为区内找矿提供了新的勘查思路。     

Radiometric survey for exploration of hydrothermal alteration in a volcanic area

A radiometric survey on a sector of the Lipari volcanic island particularly affected by argillification due to hydrothermal processes was carried out. Preliminarily, on the basis of a wide set of field measurements over unaltered outcrops U and K distribution maps were obtained. The concentration of these radioelements increases with the degree of magma differentiation; the U and K content shows maxima (13.4 ppm and 3.7% on average, respectively) in the felsic materials, belonging to the youngest volcanic cycles, and minima (2.7 ppm and 2.0%) in the mafic rocks of the oldest cycles. The Th/U ratio insignificantly varies with magma differentiation and it equals 3.2. Laboratory measurements on volcanic products from altered zones were then used to identify radiometric anomalies related to hydrothermal processes. On the average, argillized rocks have radioactivity approximately five times lower than that measured in the unaltered volcanics. The Th/U ratio against U is rather uniform, whereas Th/K ratio is of the order of 3.6 in less altered rocks K > 0.2%) and it ranges from 7 to 11 in kaolin deposits having the largest depletion in potassium.     

Effects of prescribed burnings on soil hydrological parameters

Prescribed burning is a forest management tool to reduce forest fire hazards. It is largely applied in the USA and is gaining importance worldwide, particularly in Europe. However, its effects on soils still have to be better understood. This study analyses the effects of two types of prescribed burnings (i.e. low and high burn severities of up to 200 °C and at or above 400 °C) on soil hydrophobicity, infiltration, and water storage capacity of top soils. Prescribed burnings were performed on four different plots in southern and western Catalonia, Spain. Soil samples were collected before and after burning to assess water repellency with the water drop penetration time (WDPT). Three rainfall simulations before burning and three after burning were executed on areas of 1 m², and soil water contents at four to five depths were measured every 4 min during and after rainfall simulations using time domain reflectometry equipment (TDR). Following burning at both severities, water storage capacity of the top soil decreased between 1·7 and 5·4%vol on all four plots. No significant changes in volume flux density and velocity of the wetting fronts were discernible. Water drop penetration times increased moderately at the soil surface of the plots that were exposed to the high burn severity, and decreased slightly when burn severity was low. On two of the four plots the presence of partially moist organic litter prevented the underlying soil from excessive heating. Changes in hydrophobicity and water storage capacity of the top soil did not affect infiltration. Copyright © 2008 John Wiley & Sons, Ltd.     

Melting of subducted continent: Element and isotopic evidence for a genetic relationship between Neoproterozoic and Mesozoic granitoids in the Sulu orogen

Zircon U-Pb and hornblende Ar-Ar ages, major and trace elements, and Sr, Nd and O isotope compositions of Neoproterozoic and Mesozoic granitoids from the Wulian region in the Sulu orogen of China demonstrate that post-collisional granitoids were generated by Early Cretaceous melting of subduction-thickened continental crust that has geochemical affinities to Neoproterozoic protolith of ultrahigh-pressure metaigneous rocks that were derived from the Yangtze Block. The Mesozoic granitoids share the following features with the Neoproterozoic granites: (1) occurrence of Neoproterozoic U-Pb ages in zircon; (2) strong LREE enrichment but HFSE (Nb, P and Ti) depletion; (3) variable δ¹⁸O values for constituent minerals; (4) significantly negative ε_Nd(t) values with Paleoproterozoic Nd model ages. Thus the two ages of granitoids have a genetic relationship in source nature. However, they differ significantly in both the O isotope composition of zircon and the concentration ratios of fluid-mobile to fluid-immobile elements. These differences are interpreted to reflect differences in the depth of magma sources, and in the nature of subsequent water-rock alteration. The Neoproterozoic granites were derived from hydration melting of Paleoproterozoic crust during breakup of the supercontinent Rodinia at ca. 780 to 740 Ma along the northern margin of the Yangtze Block, with subsequent overprinting of high-T meteoric-hydrothermal alteration and rifting-induced low-¹⁸O magmatism. In contrast, the Mesozoic granitoids were derived from dehydration melting of subduction-thickened crust that was unaffected by meteoric-hydrothermal alteration. The source of the Mesozoic granitoids may be coeval middle-lower crustal counterparts of the Neoproterozoic granites.     

土地利用对河西走廊荒漠绿洲区土壤入渗的影响

绿洲是由农田、林地、沙荒地、湖泊和湿地等多种景观组成的镶嵌体,农田、林地、沙荒地是该镶嵌体的主要组成部分。探究不同土地利用土壤入渗特征对深入了解绿洲内部水循环和水转化具有重要意义。本文研究了农田、防护林地和沙荒地3种土地利用方式0—40 cm土层土壤物理性质及入渗特征,探讨不同土地利用对土壤入渗特征的影响及其驱动机制。结果表明：（1）不同土地利用土壤质地差异显著,较沙荒地,防护林地和农田0—40 cm土层土壤黏粉粒含量分别增加了100.25%和285.23%,土地利用对干密度和总孔隙度影响较小,仅防护林地表层（0—10 cm）干密度减小（1.37±0.12 g·cm^-3）、总孔隙度增大（48.22%±4.56%）;（2）不同土地利用方式土壤入渗性能存在显著差异,与沙荒地相比,农田和防护林地土壤初始入渗率分别减小了75.49%和37.05%,饱和导水率分别减小了80.04%和42.02%;（3）不同土地利用方式显著影响土壤水流模式,防护林地和农田土壤水流入渗非均匀性显著高于沙荒地,其优先流比分别是沙荒地土壤的3.84倍和5.46倍;（4）土壤初始入渗率和饱和导水率与黏粉粒含量显著负相关,优先流比和长度指数与黏粉粒含量和总孔隙度显著正相关,土壤入渗性能和水流模式均受土壤质地的影响,表明土壤质地是土地利用对土壤入渗影响的关键因子。     

云南巍山笔架山锑矿床成因

矿区褶皱和断裂相互重叠交错,为含矿热气液的运移提供了导矿及储矿构造。微量元素测定,确定上三叠系地层为锑的矿源层,矿体严格受层位控制,三合洞组灰岩破碎带为含矿层位,是找矿主要标志。依据矿床产出特点及物理化学条件,确认该矿床属中低温热液富集层控矿床。     

Hydrothermal dolomitization of the carbonate Jurassic succession in the Provençal and Subbriançonnais Domains (Maritime Alps,North-Western Italy)

The present article illustrates a straightforward case of hydrothermal dolomitization, affecting Jurassic platform limestones of the Provençal and Subbriançonnais Domains (Maritime Alps, North-Western Italy). Dolomitized bodies are randomly distributed within the host limestone, and are commonly associated with dolomite vein networks and tabular bodies of dolomite-cemented breccias discordant with respect to bedding. Main dolomite types are a finely to medium-crystalline replacive dolomite and a coarsely-crystalline saddle dolomite occurring both as replacive and as cement. Stratigraphic constraints indicate that dolomitization occurred during the Cretaceous, in a shallow burial context, and was due to the circulation of hot fluids (temperature about 200 °C, as indicated by fluid inclusion microthermometry) through faults and related fracture networks. Hydrothermal dolomitization therefore indirectly documents a Cretaceous fault activity in the Maritime Alps segment of the European Tethyan passive margin.     

Search condition of purification materials and their proper processing for the rapid infiltration method

The purpose of this study is to do an experiment in finding conditions of search purification materials and the way of their proper processing for the rapid infiltration method. It seems that this result makes an index of further selection of a purification material. This experiment is to conduct sorption tests of fulvic acid and phosphoric acid regarding Kanuma-soil （volcanic ash soil） with iron oxide and aluminum oxide, to fred relationship between sorption coefficients and heating temperature, concentrations of iron and aluminum. The sorption experiment on heated and unheated materials was conducted at 25℃ in a dark place at the solid to liquid ratio of 1 ： 2.5. The liquid is simulated river water. According to the result of the study, a deference was found of the best heating temperature between sorption coefficients of fulvic acid and phosphoric acid. The peak of a sorption coefficient of fulvic acid is 800℃, however the peak of a sorption coefficient of phosphoric acid is 400℃. In the case of fulvic acid, it is high sorption coefficients when Kanuma-soil with aluminum oxide is unheated and heated as 400℃. However, sorption coefficients when Kanuma-soil with iron oxide is not conspicuously different when heated, and coefficients are descended gradually more than 600℃. Sorption coefficients of unheated Kanuma-soil are descended when adding iron oxide. When heating temperature is higher, pH of water is higher. High pH causes to descend sorption coefficient, however it is remarkable result that sorption coefficient is ascended at 800℃. In the case of phosphoric acid, it is high sorption coefficient when Kanuma-soil is heated at 400℃, and Kanuma-soil with aluminum oxide is heated between 200℃ and 400℃. Sorption coefficients of Kanuma-soil with iron oxide are the highest when unheated, but sorption coefficients of Kanuma-soil with iron oxide are the highest when heated.