Petrochemical study of Al-Mizil plutonic rocks of Saudi Arabia

A petrochemical study of some rock samples has been carried out using different experimental techniques. The rock samples were collected from the Al-Mizil area, Saudi Arabia. Al-Mizil area consists of Precambrian metasediments which belong to the Halaban Formation. The plutonic rocks later intruded into the Halaban Formation. Major oxides and trace elements in these rocks are presented. The study indicates that the rocks are mainly of granitic composition. The petrochemical data suggest a magmatic origin for Al-Mizil granitic rocks.     

Boron concentration measurements by prompt gamma activation analysis: Application on miocene-quaternary volcanics of the Carpathian-Pannonian Region

Prompt gamma activation analysis is a highly powerful analytical method in geology, due to its applicability to determine the concentration of all major and few trace elements in whole rock samples. Furthermore, the boron concentration can be determined with proper accuracy without time consuming sample preparation. The reliability of this method was checked on geological standards and on other volcanic rocks, which were analyzed previously by XRF and TIMS for many major and trace element components and Sr-isotopes. Boron concentrations of volcanic rock samples from the East Carpathian Volcanic Field (Eastern-Central Europe) are reported here for the first time. The boron concentrations were measured for an improved definition of the petrogenezis of these rocks and to understand the fluid addition processes during subduction-related volcanism in this region.     

Tendency and Fractal Pattern of Migration of Trace Elements in Source Rocks During Thermal Event

The reactivation of trace elements in source rocks is fundamental in the formation of many economic deposits. Although transport by fluid flow and infiltration is very effective along visible fractures, the migration of trace elements from the inner part of solid cells to the weaknesses is much less efficient, and so becomes the bottleneck in the migration of these elements from their initial positions in the source rock to the final deposition site in an ore body. Diffusion may play a key role in the reactivation of trace elements. The overall migration pattern of trace elements in source rocks is characterized by an embedded sink mosaic structure, which possesses the self-similarity of a fractal. There are two general migration tendencies of trace elements. One is from within solid cells, such as mineral grains, toward the sink, consisting of weaknesses in the source rock. The other is from high-temperature fields toward low-temperature ones. High temperature favors the realization of these two tenden     

Boron and chlorine concentration of volcanic rocks: An application of prompt gamma activation analysis

Summary Boron and chlorine concentrations in geological standards and in representative volcanic rock samples were determined by prompt gamma activation analysis (PGAA). The results of the GSJ standard measurements proved the high precision of PGAA in measuring the boron, chlorine, other trace elements (Sc, Nd, Sm, and Gd) and the major element contents of the samples. The rock samples originate from the western part of the Northern-Pannonian Volcanic Field (NPVF), which includes the Central Slovakian Volcanic Field (CSVF), the Börzsöny and the Visegrád Mts. (VMt.). The oldest 16-13.5 Ma samples as the first products of the Miocene calc-alkaline volcanism are the most enriched in B (11-29 µg/g), whereas the primitive basaltic andesites (from CSVF), the latest products (9 Ma) of the volcanic activity have lower B content (8-9 µg/g). The measured B concentrations correlate positively with fluid-mobile elements, and the trace element pattern of the samples show subduction related signatures. The chlorine content of the investigated samples shows wide variation between 42.62 and 1148.45 µg/g. The 9 Ma samples from the CSVF show Cl contents between 150-160 µg/g. In agreement with the latest geodynamic models of the Neogene calc-alkaline volcanism^1,2 in the NPVF during the shallow, prograding subduction, the fluid-mobile elements metasomatized the mantle wedge. Thus the oldest volcanic rocks have relatively higher B (>11 µg/g) and high but variable Cl contents. As the subduction waned and extension proceeded, the magma generation region changed to a not thoroughly metasomatized mantle by the former subduction event, resulting in lower B, low and stable Cl content of the younger (9 Ma) volcanic rocks.     

Uniform micro-sized alpha- and beta-Si3N4 thin ribbons grown by a high-temperature thermal-decomposition/nitridation route

Uniform micro-sized alpha- and beta-Si(3)N(4) thin ribbons have been achieved by a high-temperature thermal-decomposition/nitridation route. As-grown ribbons were characterized by using powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, electron energy loss spectroscopy, and cathodoluminescence. These alpha- and beta-Si(3)N(4) ribbons are structurally uniform micro-sized single crystals, and have a width of approximately 2-3 microns, a thickness of approximately 20-60 nm, and a length, that ranges from several hundreds of microns to the order of millimeters. A room-temperature cathodoluminescence spectrum recorded from these ribbons shows one intensive blue emission peak at approximately 433 nm. The growth for the new ribbon form of this material is believed to be dominated by a vapor-solid process.     

EPMA Major and Trace Element Analysis in Garnet and its Petrological Application

 A comparison between major and trace element concentrations in garnet performed by electron microprobe (EPMA) technique is reported. Quantitative spot analyses and X-ray maps of major elements (Fe, Mg, Mn, Ca) and the trace element yttrium in garnets from metamorphic rocks are presented. The selected garnet samples come from meta-pelitic and meta-basic specimens belonging to the tectonic unit of the Monte Rosa Nappe (Western Alps). In the metapelites, the quantitative Y distribution maps display a prominent increase at the core, the Y abundance varying by over two orders of magnitude, from about 80 ppm (rim) to over 2100 ppm (core). The Y profiles show well defined patterns with sharp features that do not correlate with major element distributions. A roughly comparable pattern can be supposed only with Mn. The Y distribution suggests that the diffusion of Y through the garnet is very slow compared to the major elements, thus the Y results are suitable for geothermometric estimates. In the metabasites, the Y spatial distribution is characterised by an increasing content from the core to the rim, displaying a zoning pattern opposite to the metapelite garnet. Quantitative EPMA analyses range from 1100 ppm at the rim to values lower than the detection limit at the core. Therefore, the Y content in the garnet can be related to several chemical and physical variables such as the bulk rock composition and the phase assemblage. In particular, in the xenotime-bearing metapelitic system the Y distribution seems to be correlated with metamorphic peak temperature.     

北阿尔泰火山岩形成机制的稀土判别

研究了北阿尔泰地区泥盆纪及石炭纪火山岩的稀土元素特征,并应用稀土判据探讨了区内火山岩的形成机制。稀土元素与常量元素相关关系显示,北阿尔泰泥盆纪及石炭纪火山岩成岩过程中分离结晶作用不明显,其形成机制可能为部分熔融作用。多种稀土元素联合协变关系的研究进一步表明,北阿尔泰泥盆纪及石炭纪火山岩的形成机制为部分熔融作用。同时也显示区内泥盆纪及石炭纪火山岩的稀土元素继承了其源区物质的稀土元素特征。     

Studies of LA-ICP-MS on quartz glasses at different wavelengths of a Nd:YAG laser

The capability of LA-ICP-MS for determination of trace impurities in transparent quartz glasses was investigated. Due to low or completely lacking absorption of laser radiation, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) proves difficult on transparent solids, and in particular the quantification of measurement results is problematic in these circumstances. Quartz glass reference materials of various compositions were studied by using a Nd:YAG laser system with focused laser radiation of wavelengths of 1064 nm, 532 nm and 266 nm, and an ICP-QMS (Elan 6000, Perkin Elmer). The influence of ICP and laser ablation conditions in the analysis of quartz glasses of different compositions was investigated, with the laser power density in the region of interaction between laser radiation and solid surface determining the ablation process. The trace element concentration was determined via calibration curves recorded with the aid of quartz glass reference materials. Under optimized measuring conditions the correlation coefficients of the calibration curves are in the range of 0.9-1. The relative sensitivity factors of the trace elements determined in the quartz glass matrix are 0.1-10 for most of the trace elements studied by LA-ICP-MS. The detection limits of the trace elements in quartz glass are in the low ng/g to pg/g range.     

Studies of LA-ICP-MS on quartz glasses at different wavelengths of a Nd:YAG laser

The capability of LA-ICP-MS for determination of trace impurities in transparent quartz glasses was investigated. Due to low or completely lacking absorption of laser radiation, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) proves difficult on transparent solids, and in particular the quantification of measurement results is problematic in these circumstances. Quartz glass reference materials of various compositions were studied by using a Nd:YAG laser system with focused laser radiation of wavelengths of 1064 nm, 532 nm and 266 nm, and an ICP-QMS (Elan 6000, Perkin Elmer). The influence of ICP and laser ablation conditions in the analysis of quartz glasses of different compositions was investigated, with the laser power density in the region of interaction between laser radiation and solid surface determining the ablation process. The trace element concentration was determined via calibration curves recorded with the aid of quartz glass reference materials. Under optimized measuring conditions the correlation coefficients of the calibration curves are in the range of 0.9–1. The relative sensitivity factors of the trace elements determined in the quartz glass matrix are 0.1–10 for most of the trace elements studied by LA-ICP-MS. The detection limits of the trace elements in quartz glass are in the low ng/g to pg/g range.     

Preparation and certification of high-grade gold geochemical reference material

One high-grade gold geochemical reference material-BND 3401.01 has been prepared by the National Geophysical Research Institute (NGRI), Hyderabad in collaboration with the Hutti Gold Mines Company Limited (HGML), Hutti and National Physical Laboratory (NPL), New Delhi, in India. The sample is a sheared gold-sulphide-bearing quartz vein emplaced in a sheared acid volcanic rock that was collected at the 2400-foot level from the middle reef of Hutti deposit located in the north-western periphery of the late-Archaean Hutti-Maski greenstone belt, Karnataka, India. Fifteen institutions in India, Canada, China and Tanzania having experience in geochemical analysis had participated in this collaborative analysis programme. The sample was extensively characterized for its major, minor, trace and ultra-trace element composition by using a variety of analytical techniques. Usable values were provided for major, minor and several trace elements including all rare earth elements (REE). The certified value for the gold concentration in BND 3401.01 gold ore is 12.1±0.7 mg/kg.     

Mössbauer Investigation of Characteristic Distribution of Iron Oxides in Sediments from the Antarctica

Sediments from the Admiralty Bay, King George Island, Antarctica, were investigated by ⁵⁷Fe Mössbauer spectroscopy, X-ray diffractometry, and radiometry. Quartz, feldspar, chlorite, calcite, dolomite, mica, kaolinite, hematite and magnetite were identified as constituent minerals in the sediment samples. The phase composition and the iron distribution among the crystallographic sites of iron-bearing minerals (silicates, magnetite and hematite) of samples from different location have been derived from the complex Mössbauer spectra. At different locations sediments had significant characteristic differences in the mineral composition, in the iron distribution among the crystallographic site of silicates, and in the specific radioactivity of Cs radionuclides. These results indicate differences in the rock formation and alteration by the sediments in this maritime part of Antarctica. There is a much higher amount of iron oxides in the sediments from south part of the geological fault across the Admiralty Bay than in the north part. This can be associated with much more alteration in the rocks in the south part compared to the northern one. This finding can contribute to the question of the history of the formation and alteration of volcanic rocks in the border of Antarctica.     

Chemical Investigation of Coloured Minerals in Natural Stones of Commercial Interest

The economic interest in natural stones provides an interesting input to the study of coloured rock-forming minerals. Generally, the colour of a mineral is attributed either to the presence of intrinsically-coloured constituents or of trace elements substituting major elements in the crystallographic sites, or to physical factors such as crystal lattice defects. We have analysed the blue and blue-green silicate minerals dumortierite and amazonite, coming from Mozambique quartzites, and from Malawi and Brazil granitoids, respectively. This study was performed by a multiple analytical approach including (a) a comparison of different signals (optical light-polarized images, backscattered electron images and X-ray multielemental maps); and (b) a collection of quantitative data obtained by WDS systems for major elements, and by WDS and/or micro-PIXE facility for trace elements. A good correlation between Ti concentration zoning and pleochroism variations was observed in dumortierite. In addition, the blue dumortierite of Mozambique, with its unusual significant amounts of antimony (about 5 wt.% Sb₂O₃), represents a mineral with an intermediate composition between dumortierite and holtite. In amazonite the aquamarine colour seems to be related to the Pb content on the order of some hundreds of ppm.     

内蒙古中部渣尔泰山群微量元素地球化学特征

通过对内蒙古中部渣尔泰山群各层位岩石采样,对该山群中共43个微量元素（含稀土元素）与地壳丰度进行了对比分析,总结了该山群微量元素的地球化学特征。研究表明,该山群富集W、Re、Cu、Pb、Co等元素,而In、V、Cr、Ni等元素亏损较严重;微量元素在板岩和云母石英片岩中相对含量较高,在灰岩中相对贫化;此外,该山群稀土元素地球化学特征表现为轻稀土富集,重稀土亏损;具有明显的Eu的负异常,Ce的弱正异常。     

Chemical analyses of martian soil and rocks obtained by the Pathfinder Alpha Proton X-ray spectrometer

The US Mars Pathfinder spacecraft, which landed on the red planet on the 4th of July 1997, carried an Alpha Proton X-ray Spectrometer (APXS) that obtained the chemical composition of martian soil and rocks. The principles of the APXS operation are based on three interactions of alpha particles with matter: Rutherford alpha backscattering; (, p) nuclear reactions; and X-ray generation by charged particles and X-ray excitation. The APXS, as was implemented on the Pathfinder mission, uses for all three modes of operation a monoenergetic beam of alpha particles from about 40 mCi of ²⁴⁴Cm radioisotope. It employs Si charged particle detectors for alpha and proton modes and a specially designed silicon PIN detector for its X-ray mode that does not require cooling for its operation. The APXS can detect all of the elements (except H and He) present above a few tenths of a percent for all major elements and several hundred ppm for many minor and trace elements.

The APXS on Pathfinder was transported to various locations on the martian surface by the Sojourner rover which enabled it to analyze multiple soil and rock samples selected by the science team from the lander camera images. The APXS performed excellently under the adverse martian environment conditions and provided important information about the chemical composition of the martian soil and rocks. All of the analyzed rocks at the Pathfinder site were found to have high concentrations of silica, sulfur and iron, and low in magnesium, similar to those of the terrestrial basaltic andesites and definitely different from the SNC meteorites that are believed to have originated from Mars. All of the soil samples analyzed by the APXS have similar composition and are very close to the soil analyses obtained by the two Viking missions. The information derived from the Pathfinder APXS has significant implications about the origin and evolution of planet Mars.     

江南隆起带皖赣相邻区燕山期岩浆岩稀土对比研究

对比研究了江南隆起带皖南地区与赣东北地区燕山期岩浆岩的稀土元素地球化学特征，稀土元素特征反映出，皖南地区燕山期岩浆岩属于典型的壳源岩浆岩，而赣东北地区燕山期岩浆岩则具有幔源特征，这是赣东北地区燕山期与岩浆岩有关的多金属矿床发育、而皖南地区不发育的重要原因。稀土元素的研究结果同时得到地球物理、成岩构造背景、稳定同位素等研究的证实，也表明稀土元素在岩浆岩成岩物质来源方面有很好的示踪作用。     

煤中矿物质及其燃烧后的变化分析

以淮北煤田6煤层煤为样品，采用中子活化法、化学方法、X射线衍射及扫描电镜等方法对煤及其灰样品中的矿物质、微量元素进行了分析，在此基础上，研究了样品中主要矿物的种类及其形成时的影响因素，分析了它们在燃烧前后的主要变化。通过分析可知，样品中主要含有高岭石、石英、方解石和黄铁矿以及多种微量元素；在燃烧过程中，微量元素的含量以及矿物的种类发生了变化，并形成高温稳定的矿物种类。     

CHEMICAL SPECIES OF IRIDIUM AND OTHER TRACE ELEMENTS AT K-T BOUNDARY CLAY LAYER, STEVNS KLINT, DENMARK, AND ITS IMPLICATION

The chemical species of anomalous Ir in the Fish Clay K-T boundary at Stevns Klint, Denmark, was studied by using a newly-developed chemical stepwise dissolution procedure and neutron activation analysis. The experimental results indicate that the anomalous Ir mostly exists in the acid-insoluble residue phase. The Ir pattern of the K-T boundary resembles that of the Ningqiang carbonaceous chondrite, while remarkably different from those of the ultrabasic rock and volcanic lava. Thus, we deduce that the Ir anomaly at K-T boundary is mainly extraterrestrial, instead of volcanogenic or geochemical enrichment origin. The patterns of other trace elements in various phases also confirm the above conclusion.     

Major element analysis of selected rock and volcanic ash samples in the Unzen area,Japan, by X-ray fluorescence spectroscopy

Determination of major elements in natural solid samples by X-ray fluorescence spectroscopy (XRF) with a fusion disc technique is described. Data obtained by the present XRF analytical system were found to have satisfactorily high reliability. Five rock samples and a volcanic ash sample with varying ages ranging from the present to 180 000 years, derived by the current and past volcanic activities in the Unzen area, Nagasaki, Japan were analyzed for their major elements' compositions using the above mentioned system. The chemical composition of the magma under this area has changed very little at least over the last 180 000 years.     

富蕴县阿克塔斯铜金矿床火山岩地球化学

阿克塔斯铜金矿区位于新疆富蕴县内,矿区主体位于东准噶尔北部,靠近阿尔泰与北准噶尔两个具有不同构造特征和演化历史的构造单元。阿克塔斯金铜矿体主要赋存于石英脉、斜长花岗岩、蚀变安山岩及接触带内的千枚岩破碎带中。根据安山岩的微量元素分配模式的研究发现,岩浆在演化的过程中有大陆地壳的物质加入其中并进行混染。通过对含矿石英脉中黄铁矿和黄铜矿中的硫进行同位素分析,表明黄铁矿、黄铜矿中硫可能都来源于地幔。矿区区域地球化探异常发育,金、铜、砷元素含量高、相关性好,并与火山―岩浆岩有密切空间关系,是寻找评价与火山岩以及浅成岩有关铜金矿的有利地段。     

黔西南卡林型金矿床稀土元素地球化学特征

分析了黔西南地区板其、、丫他及戈塘等卡林型金矿床的(La/Yb)N、(La/Sm)N、∑REE及LREE/HREE等稀土元素的含量及参数特征.结果表明,该区金矿床相对富集LREE;该区戈塘金矿具有明显的MREE富集及正Eu异常的特点,表明成矿热液应该是一种还原性流体,来源于深部或至少经历过对富含斜长石源区的水-岩反应矿...