The hematite–goethite enhancement model of loess and an ‘irregular’ case from Paks,Hungary     

B. Bradk  Y. Seto  D. Csonka  T. Vgh  J. Szebernyi 《第四纪科学杂志》2019,34(4-5):299-308

On the basis of a key model of the appearance of hematite and goethite in some Chinese and European loess successions, paleosols generally contain higher proportions of hematite formed by pedogenic processes during warm and humid interglacials, while loess contains sedimentary goethite deposited during colder, glacial periods. Rock magnetic measurements were conducted on samples from Paks (Hungary) loess, revealing an anomalous case. Sediments were found to contain higher amounts of hematite and/or goethite, while the well‐developed paleosols were found to be lacking in hematite but had significant amounts of magnetite and maghemite. This observation demonstrates that the character of pedogenic magnetic mineral alteration and neoformation differs from the hematite/goethite model; the model is therefore not applicable to the Paks succession, possibly due to differences in the regional paleoclimate and pedogenic environment. The results indicate the existence of a further model, in which hematite formation is not significant in the course of pedogenesis.  相似文献   

酸性环境下生物成因施氏矿物稳定性研究          下载免费PDF全文

谢越  周立祥 《地学前缘》2011,18(5):310-318

施氏矿物是酸性矿山废水中广泛存在的次生矿物,其形成和转化受环境pH值、温度和共存离子等条件影响。文中研究了酸性环境中生物成因施氏矿物和吸附了三价砷的生物成因施氏矿物,在不同温度和钾离子浓度条件下的稳定性。结果表明,老化温度的增加促进施氏矿物相的转变:4℃条件下,在15周的老化时间里,无砷及含砷施氏矿物均未发生相转变;而在40℃条件下,经过15周的老化,则无砷和含砷施氏矿物均发生了部分相转变。此外,钾离子浓度变化可以导致施氏矿物老化产物不同:生物成因施氏矿物在0.01mM钾离子条件下老化15周后的转化产物主要为针铁矿,在100mM钾离子条件下老化产物为黄钾铁矾和针铁矿。含As(Ⅲ)施氏矿物在0.01mM钾离子条件下老化15周后没有发生相转变,在100mM钾离子条件下发生了部分相转变,产物为黄钾铁矾。生物成因施氏矿物中的As(Ⅲ)使得矿物在环境中更加稳定。  相似文献   

安徽铜陵地区不同粒级土壤中元素含量 与矿物组成分布特征     

魏华玲  周国华  孙彬彬  刘占元  曾道明 《地质通报》2013,32(11):1861-1865

土壤矿物和粒级组成及其与土壤元素关系的研究对土壤生态环境和肥力评价具有重要意义。对安徽铜陵地区土壤的研究发现,不同粒级段土壤中元素富集程度不同,不同元素的富集粒级也不尽相同,-200目细粒级中各种元素含量最低。研究表明,土壤不同粒级段的矿物组成不同,伊利石和针铁矿对Cu、Zn、Cd、Pb、As等元素具有较强的吸附作用。  相似文献   

Hickman Crater,Ophthalmia Range,Western Australia: evidence supporting a meteorite impact origin ∗     

A. Y. Glikson  A. H. Hickman  J. Vickers 《Australian Journal of Earth Sciences》2013,60(8):1107-1117

A newly discovered, morphologically well-preserved crater with a mean diameter of 260 m is reported from the Ophthalmia Range, Western Australia. The crater is located in hilly terrain ～36 km north of Newman, and is situated in the Paleoproterozoic Woongarra Rhyolite and the overlying Boolgeeda Iron Formation. The morphometry of the crater is consistent with features characteristic of small meteorite impact craters. The rhyolite of the crater's rim exhibits widespread shatter features injected by veins of goethite bound by sharply defined zones of hydrous alteration. The alteration zones contain micro-fractures injected by goethite, which also fills cavities in the rhyolite. The goethite veins are interpreted in terms of forceful injection of aqueous iron-rich solutions, probably reflecting high-pressure hydrothermal activity by heated iron-rich ground water. None of these features are present in the Woongarra Rhyolite outside the immediate area of the crater. Petrography of the rhyolite indicates possible incipient intracrystalline dislocations in quartz. The Boolgeeda Iron Formation, which crops out only on the southern rim of the crater, displays brecciation and mega-brecciation superposed on fold structures typical of the banded iron-formations in the region. Geochemical analysis of two goethite veins discloses no siderophile element (Ni and PGE) anomalies, negating any contribution of material from an exploding meteorite. Instead, the strong iron-enrichment of the fractured rhyolite is attributed to a hydrothermal system affecting both the Boolgeeda Iron Formation and the Woongarra Rhyolite, and localised to the area of the crater. An absence of young fragmental volcanic material younger than the Woongarra Rhyolite is inconsistent with an explosive diatreme, leading us to a preferred interpretation in terms of an original impact crater about 80 m deep excavated by a ～10 m-diameter projectile and accompanied by hydrothermal activity. A minor north–south asymmetry of the crater, and an abundance of ejecta north, up to about 300 m northwest and northeast of the crater, suggest high-angle impact from the south. A youthful age of the structure, probably Late Pleistocene (10⁴–10⁵ years old), is indicated by damming of the drainage of a south-southeast-flowing creek by the southern crater rim.  相似文献   

生物矿化针铁矿对造纸废水的吸附和热解吸研究   总被引：1，自引：0，他引：1  

方继敏  孟雅文  杨红刚  孙振亚  马涛 《矿物学报》2006,26(4):368-372

利用生物矿化针铁矿对造纸废水进行吸附实验,对吸附动力学、影响因素、以及吸附等温线等进行了研究,通过DTA和XRD研究了不同煅烧温度条件下生物矿化针铁矿的物质形态变化,分析了不同再生条件对生物矿化针铁矿的吸附容量的影响。结果表明:生物矿化针铁矿对造纸废水中的污染物吸附速度较快,具有良好的吸附性能;生物矿化针铁矿吸附污染物后经过煅烧可以实现再生,经310℃煅烧后的第一次再生吸附率为原针铁矿的97.3%,多次加热再生后仍然具有很高的吸附能力。  相似文献   

Goethite Morphology and Composition in Banded Iron Formation, Orissa, India     

Birendra Kumar Mohapatra    Subhasmita Jena    Khageswar Mahanta  Patitapaban Mishra 《Resource Geology》2008,58(3):325-332

Iron ore deposits are generally described in terms of size, grade and chemical composition rather than the mineralogical and microstructural characteristic of different ore types. It is essential, however, to know the morphology, microstructure and chemical composition of individual minerals for optimum mineral processing. Goethite is reported to occur as a ubiquitous phase in many iron ore types and is particularly abundant in the Precambrian banded iron ore formation of north Orissa, India. Goethite from the Bonai–Keonjhar Belt in Orissa has been examined in terms of its morphology and microstructure in relation to chemical composition. Electron microscopy indicated several goethite morphotypes including botryoidal, nodular, spheroidal, platy, stalactitic and flaky. These different morphotypes display intergranular, intragranular, wedge, reniform, comb, prismatic, cavity-line and bead microstructures. In situ analysis using electron probe microanalyzer indicated a wide compositional variation among the different morphotypes and microstructures. Goethite replacing hematite is generally devoid of deleterious elements while re-precipitated goethite generally contains adsorbed alumina, silica and/or phosphorus. Nodular goethite commonly has a high phosphorus level while botryoidal, spheroidal and platy goethite often contains increased combined alumina and silica. Goethite having a reniform, wedge, intergranular or intragranular microstructure is highly water bearing and cryptocrystalline in nature. During dehydration, bead, comb, cavity-lined or prismatic goethite develop, which are more crystalline and which have a higher iron concentration. Goethite with a wedge, prismatic or bead-type microstructure has a higher adsorption of silica (2–4%), while goethite having an intergranular, bead or prismatic microstructure invariably contains appreciable phosphorus, generally at levels deleterious to processing.  相似文献   

铜陵新桥矿田褐铁矿矿物组成及成因     

刘诗贝  徐亮  陈平  谢巧勤  陈天虎  刘海波 《岩石矿物学杂志》2016,35(3):531-542

褐铁矿是铁帽型金矿和铁矿的重要矿产类型,但目前对其从矿物学的微观角度研究较少。本文采用粉晶X射线衍射(XRD)以及场发射扫描电镜(SEM)矿物学研究手段,对铜陵矿集区新桥矿田褐铁矿的矿物组成、微结构进行研究。根据矿物组成及微结构将新桥褐铁矿分为两种成因类型:Ⅰ型褐铁矿,该类型褐铁矿主要起源于黄铁矿矿石,矿石多具蜂窝状构造。主要组成矿物为针铁矿,次要矿物为赤铁矿,含有少量石英,针铁矿晶体长度一般介于500 nm~2μm,长度/半径比值(长径比)较大;Ⅱ型褐铁矿,由原生菱铁矿矿石风化而成,矿石多具肾状构造。矿物组成主要为针铁矿,其次为赤铁矿、锰氧化物和伊利石等粘土矿物,针铁矿晶体长度一般小于500 nm,具有较小的长径比。褐铁矿矿物学和微结构不仅可以初步确定原生矿物和矿石类型,而且对寻找铁帽金矿床也具有重要指示意义。  相似文献   

The application of potentiometric techniques to study complexation reactions at the mineral/water interface     

Staffan Sjöberg  Lars Lövgren 《Aquatic Sciences - Research Across Boundaries》1993,55(4):324-335

The most widely used technique to characterize the acid/base and complexing properties of hydrous particle surfaces is based on potentiometric titrations. Properly applied it provides accurate data over wide concentration ranges and, with help of automatic measuring and data collecting systems, it has become possible to collect large amounts of data within a reasonably short time period. However, collection and interpretation of experimental data is beset with difficulties. Some of these difficulties are identified and discussed with special reference to some goethite systems.  相似文献   

共存重金属离子对针铁矿活化过硫酸盐去除水中磺胺吡啶的影响     

周景尧  李哲  陈家玮 《地学前缘》2019,26(4):295-300

基于硫酸根自由基的高级氧化技术能有效降解水中磺胺类药物残留。由于在自然环境中共存重金属会对环境修复效果产生一定影响,文中重点研究了不同pH环境条件下不同重金属离子对针铁矿活化过硫酸盐(PS)去除水中磺胺吡啶(SPY)的影响。不同类型重金属离子(Cu^2+、Pb^2+、Cd^2+,0.2mmol/L)在反应体系(初始条件:针铁矿,1.0g/L;PS,4mmol/L;SPY,10mg/L;pH=8.2)中对SPY的降解对比研究发现:在无重金属共存的条件下,针铁矿/PS体系降解SPY的去除率为25.2%;Pb^2+和Cd^2+对针铁矿/PS体系的影响较弱,去除率分别为30.8%和34.8%;Cu^2+的促进作用很大,可以使SPY被完全降解(100%)。机理分析认为,在针铁矿/PS体系中Pb^2+和Cd^2+主要通过影响吸附作用导致磺胺吡啶被去除,而Cu^2+主要通过自身活化PS的作用。不同pH条件(3.0,8.0,12.0)实验证实弱碱性条件下,Cu^2+/针铁矿/PS能够发挥较高的活性从而降解SPY。本文结果为采用针铁矿活化过硫酸盐技术修复类似复合污染地下水环境提供了实验依据。  相似文献   

Zn（OH）₄^2-在针铁矿（010）晶面上化学吸附结构和稳定性的理论研究     

夏树伟  钟炳伟  仇萌  于良民 《中国海洋大学学报(自然科学版)》2011,(3):57-60

采用周期性边界条件的密度泛函理论研究Zn(OH)42-在针铁矿(010)晶面的吸附结构和稳定性,得到了Zn(OH)42-吸附前后键长的变化规律。计算结果表明:当Zn(OH)42-通过共用O原子在针铁矿表面发生吸附时,平均ZnbridgeO键长较自由Zn(OH)42-的平均Zn-O键长有增长趋势,而平均Zn-O键长则有缩短趋势;Zn(OH)42-在针铁矿(010)晶面进行化学吸附时,双角DC2吸附方式为优势吸附物种。各吸附构型的稳定性顺序为DC2>SE1>DC1>SC1>SC2。  相似文献