辉绿岩侵位对半固结砂岩的改造作用--以松辽盆地东南部下白垩统为例

在偏光显微镜和扫描电镜下，发现辉绿岩．砂岩接触带附近半固结的长石砂岩中石英颗粒边部、颗粒间孔隙内及颗粒内裂隙中微晶石英发育．不论是纵向上还是横向上，距接触带较近的样品中，微晶石英多而细长．随着远离接触带，石英微晶逐渐减少，形状逐渐变的粗短．研究表明，这些微晶石英是辉绿岩侵位对围岩砂岩中碎屑石英的压溶或重结晶等作用形成的．     

The Hydrothermal Na-Ca Alteration at the Marginal Part 0f the Florina Granite and the Associated Magnetite-Hematite Bands With Thorium and Uranium Mineralization

The Oxia mineralized granite is the product of differentiation in the external parts of the Florina magmatic mass. Acidic hydrothermal solutions either of magmatic or of meteoric origin reacted with the upper tectonically fractured parts of the Florina granite and became enriched in iron, thorium, uranium, zircon and rare-earth elements. The most abundant alteration minerals are sericite and quartz, while the minerals of the mineralization bands include magnetite, hematite, thorite, monazite and zircon. The outer parts of the Oxia granite made it easy the percolation of hydrothermal solutions from the deeper heater to the upper cooler parts of the granite which acted as a hot spot.     

Aqueous alteration in the Northwest Africa 817 (NWA 817) Martian meteorite

Samples of a new Martian meteorite of the nakhlite family (NWA 817) contain traces of an iron-rich alteration product. Textural arguments indicate that this alteration product has been formed on the parent body of the meteorite (Mars). The chemical composition and structural data (X-ray diffraction, transmission electron microscopy and vibrational spectroscopy) show that the alteration mineral is a hydrous phase from the smectite family. Major elements and rare earth elements suggest that the formation of the alteration phase is related to the circulation of an aqueous fluid which composition is controlled by the dissolution of feldspars to account for a positive Eu anomaly, olivine and possibly apatite. Hydrogen isotope data display negative δD values ranging from −60 to −280‰ in olivine and pyroxenes and from −140 to −181‰ in the alteration phase. The values of δD for the alteration product show a small scatter with a mean value of −170±14‰. These values are lower than those previously obtained on other Martian meteorites, which give mainly positive δD values. These positive values have been interpreted as resulting from the interaction of the Martian meteorites with water from the Martian atmosphere. Ruling out the effect of terrestrial alteration, it is suggested that alteration in the NWA 817 meteorite was likely produced on Mars by the circulation of an aqueous fluid originating from a chemical reservoir, such as the Martian mantle, which has not equilibrated with a fractionated Martian atmosphere.     

福建福安上后洋叶蜡石矿床地质特征及找矿标志

福建福安上后洋叶蜡石矿呈似层状，赋存于晚侏罗世南园组中部火碎屑岩中，共发现有4个矿体，矿石可分为2种类型。即石英叶蜡石型和伊利石质叶蜡石型，以石英叶蜡石型为主，矿体明显受地层岩性控制，属火山热液顺层交代蚀变的似层状叶蜡石矿床。     

吉林省小石人金矿区微量元素地球化学特征

以吉林省小石人金矿区内不同类型岩(矿)石微量元素测试结果为基础,从数据结构和空间结构两方面,对微量元素的地球化学特征进行探讨。统计参数表明:所观测元素在矿区内具有明显的浓集、富集特点,在不同类型岩(矿)石中元素的分布分配也不尽相同。依据分布分配特点,可将矿区内的岩(矿)石分为正常岩石、弱蚀变岩石和强蚀变/矿化岩石3类。多元统计分析成果揭示:所观测元素都参与了金的成矿活动,但行为特点有所差异。依据多元统计特征,可将微量元素分为3个组合类型:Au、As、Sb、Bi、Hg、Mn,Cu、Pb、Zn、Ag,Co、Ni、V;第一组合为成矿成晕组合,第二组合为金的多金属矿化组合,第三组合为黄铁矿化蚀变组合;元素组合也对应于不同的矿化阶段,指示金的成矿活动及特征。土壤、岩石地化剖面显示所观测的元素间存在空间相关性,但Mn与Au相异,其异常出现在矿化蚀变带的外侧。     

河南省嵩县萑香洼金矿矿床地质特征

萑香洼大型构造蚀变岩型金矿床位于华北陆块南缘华山-熊耳山贵金属-多金属成矿带的东部,区内多期次构造岩浆活动频繁,成矿地质条件优越。矿体受F985主含金构造蚀变带严格控制。矿化作用分为五个阶段,其中钾长石-（金）黄铁矿阶段（Ⅱ）为主要成矿阶段。研究表明该矿床为浅成中低温岩浆期后热液金矿床,最佳成矿温度在180℃～265℃之间,成矿深度范围为0．68km～0．83km。成矿溶液总体以富钠、钙为特点,成矿流体为含卤素和碱质的水溶液,主要属于NaClH2O、CO2～H2O体系,主成矿阶段成矿溶液呈弱酸性,成矿后阶段为弱碱性。由早到晚δ^34S值从较小负值向较大负值变化,具深源硫特征。     

稻城地区遥感蚀变信息提取研究

根据围岩蚀变在多波段遥感图像（TM）上具有的光谱特征,利用比值分析、主成分分析及比值增强后主成分分析等方法,对 四川省稻城地区围岩蚀变信息进行提取和分析,通过多层次的筛选和评估提取矿区异常区,制作遥感异常图。     

油气对砂岩型铀矿中铀等伴生元素富集成矿的模拟实验

根据砂岩型铀矿“二次还原作用”的成矿模式,采用实验地球化学方法进行褪色蚀变模拟实验。在半动态情况下,运用含油气还原溶液与漂白砂岩和紫色砂岩反应,依此进行铀成矿作用的模拟。认为造成铀沉积的原因是由“pH落差”所致。     

30-year response to damming of a Mediterranean river in California,USA

Dry Creek is a major tributary of the Russian River in Northern California (USA) that has experienced hydrologic and morphologic alterations after the closure of Warm Springs Dam in 1983. Our objective is to present a detailed diagnosis of the modification of the creek’s flow and sediment regimes, and interpret the alterations regarding the ecomorphologic evolution previously observed in the creek. Statistical analysis of the river’s flow and sediment series indicates that dam operation has had significant impacts on the magnitude and frequency of occurrence of the highest floods, and the magnitude, variability, and duration of low and very low flows. Similarly, sediment concentration and discharge have also experienced major alterations. Loss of habitat complexity for native flora and fauna (especially endangered salmonids), channel incision, and vegetation encroachment are some of the negative trends found for the creek over the last 30 years, since river regulation began. We discuss the present dynamics of the river and propose, on that basis, the improvement of its hydromorphic functioning as part of future large-scale restoration initiatives.     

吉林省桦甸火龙岭钼矿床地质特征及其成因

燕山期酸性岩浆侵入桦甸地区晚二叠世寿山沟组中部大理岩内,发生了接触热变质和接触交代变质作用,在矽卡岩外接触带中形成矽卡岩型钼矿床,矿体与地层产状一致.围岩蚀变复杂,矿体与围岩界线明显.其矿石矿物组合简单,由辉钼矿和少量的黄铁矿、磁铁黄矿、黄铜矿、闪锌矿、白铁矿组成.