河南支建铝土矿的矿物学特征研究   总被引：5，自引：0，他引：5  

褚丙武  赵春芳 《矿产与地质》2000,14(4):251-254

河南支建铝土矿是一水硬铝石型土矿。该矿的矿物组成为一水硬铝石、高岭石、伊利石、绿泥石,赤铁矿、锐钛矿和金红石。此外,还有电气石、锆英石、磷铝锶矿等微量矿物。在扫描电镜中发现一种微量叶片状未知矿物,确定该矿物为叶蜡石。  相似文献   

Deep-Sea Sediment Compression Curves: Some Controlling Factors, Spurious Overconsolidation, Predictions, and Geophysical Reproduction     

Sinclair Buchan  Denzil Taylor Smith 《Marine Georesources & Geotechnology》1999,17(1):65-81

Oedometer tests have been carried out on 70 undisturbed surficial clays (at approximately 250 mm below the mudline), mostly collected by free-fall corers from sites widely scattered throughout the deep-sea North Atlantic. Acoustic measurements were also made, initially on contiguous samples and ultimately on the same sample using a geophysically instrumented oedometer which also collected electrical resistivity data. Apart from those quiescent areas below the carbonate compensation depth, such as north of the West Indies where very fine clays exist, most of the samples are silty clays whose geotechnical-geophysical properties are dependent on the type of clay minerals present (and their ability to take in moisture), the sand-size fraction, and the quantity of carbonate present. Thus the pure clays have high compressibilities which decrease on the addition of coarse particles, while the converse is true for the acoustic parameters, these increasing with the sand fraction. Using the notion of the intrinsic compression line for all samples, and comparison to it of the measured compression curves, it is clear that, contrary to some previously held ideas, most deep-sea clays are normally consolidated; the addition of carbonate has the effect of creating an open, stronger sediment skeleton. Interestingly, where information is available, the variation with depth of a sample's acoustic velocity follows the void ratio pressure relationship of the compression curve. This allows the construction of an in-situ sediment compression curve using the in-situ geophysical observations.  相似文献   

Pattern of spatial variability in granulometric and mineralogical characteristics across an ecologically sensitive sub-tropical wetland (Bihar,India)     

Alvia Aslam  Rajesh Kumar Ranjan  Avinash Dass 《国际泥沙研究》2023,38(4):516-529

Floodplain wetlands are dynamic systems undergoing frequent hydro-sedimentological changes. Tropical/subtropical wetlands have even more pronounced climatic and biological influences on the sediment dynamics. In the current study, a protected subtropical wetland in Bihar(India) has been assessed for its sedimentary and mineralogical status. Sediment characteristics and associated granulometric parameters are discussed to highlight the wetland’s hydrogeomorphic character, energy dimension, and th...  相似文献   

Jarosite stability on Mars     

Alexandra Navrotsky  Ferenc Lázár Forray 《Icarus》2005,176(1):250-253

Jarosite, a potassium (sodium) iron sulphate hydrated mineral, has recently been identified on the martian surface by the Opportunity rover. Using recent thermochemical data [Drouet and Navrotsky, 2003, Geochim. Cosmochim. Acta 67, 2063-2076; Forray et al., 2005, Geochim. Cosmochim. Acta, in press], we calculate the equilibrium decomposition curve of jarosite and show that it is thermodynamically stable under most present martian pressures and temperatures. Its stability makes jarosite potentially useful to retain textural, chemical, and isotopic evidence of past history, including possible biological activity, on Mars.  相似文献   

Low-Ti melts from the southeastern Siberian Traps Large Igneous Province: Evidence for a water-rich mantle source?     

Alexei V. Ivanov  Elena I. Demonterova  Sergei V. Rasskazov  Tatyana A. Yasnygina 《Journal of Earth System Science》2008,117(1):1-21

Siberian Traps Large Igneous Province (STLIP) is one of the most voluminous volcanic provinces on Earth. The dominant erupted rocks are low-Ti basalts, which make up 80% by volume of the classical Noril’sk lava sequence. In the west Siberian basin and Maymecha-Kotuy area, the low-Ti basalts make up about 99% and 50% by volume, respectively. Dolerite sills in the Angara-Taseevskaya Syncline at the southeastern STLIP exhibit trace element patterns and Sr isotope ratios typical of the low-Ti basalts of the Noril’sk sequence. The most Mg-rich (MgO 9.5–11 wt%) and hence least differentiated dolerites are characterized by trace element patterns with Ta-Nb depletion, low Ce/Pb and high Sr/Pr. These trace element features are similar to water-saturated, mantle wedge-derived island arc basalts. These imply an important role of subduction fluid-derived trace elements in the source of melting beneath the Angara-Taseevskaya Syncline and other regions of the STLIP. Less magnesium rocks (MgO 3.8–6.1 wt%) with less prominent Ta-Nb depletion, higher Ce/Pb and lower Sr/Pr could be produced via olivine-plagioclase fractionation of primary high-magnesium melts.  相似文献   

Environmental effect and genetic influence: a regional cancer predisposition survey in the Zonguldak region of Northwest Turkey     

Selahattin Kadir  A. Piril Önen-Hall  S. Nihal Aydin  Cengiz Yakicier  Nurten Akarsu  Murat Tuncer 《Environmental Geology》2008,54(2):391-409

The Cretaceous-Eocene volcano-sedimentary units of the Zonguldak region of the western Black Sea consist of subalkaline andesite and tuff, and sandstone dominated by smectite, kaolinite, accessory chlorite, illite, mordenite, and analcime associated with feldspar, quartz, opal-CT, amphibole, and calcite. Kaolinization, chloritization, sericitization, albitization, Fe–Ti-oxidation, and the presence of zeolite, epidote, and illite in andesitic rocks and tuffaceous materials developed as a result of the degradation of a glass shards matrix, enclosed feldspar, and clinopyroxene-type phenocrysts, due to alteration processes. The association of feldspar and glass with smectite and kaolinite, and the suborientation of feldspar-edged, subparallel kaolinite plates to fracture axes may exhibit an authigenic smectite or kaolinite. Increased alteration degree upward in which Al, Fe, and Ti are gained, and Si, Na, K, and Ca are depleted, is due to the alteration following possible diagenesis and hydrothermal activities. Micromorphologically, fibrous mordenite in the altered units and the presence of needle-type chrysotile in the residential buildings in which cancer cases lived were detected. In addition, the segregation pattern of cancer susceptibility in the region strongly suggested an environmental effect and a genetic influence on the increased cancer incidence in the region. The most likely diagnosis was Li-Fraumeni syndrome, which is one of the hereditary cancer predisposition syndromes; however, no mutations were observed in the p53 gene, which is the major cause of Li-Fraumeni syndrome. The micromorphology observed in the altered units in which cancer cases were detected may have a role in the expression of an unidentified gene, but does not explain alone the occurrence of cancer as a primary cause in the region.  相似文献   

Characterisation of aerosol from Santiago,Chile: an integrated PIXE–SEM–EDX study     

D. Morata  M. Polvé  A. Valdés  M. Belmar  M. I. Dinator  M. Silva  M. A. Leiva  T. Aigouy  J. R. Morales 《Environmental Geology》2008,56(1):81-95

Santiago de Chile is a big city with huge air quality problems, being one of the most polluted cities in the world. This is aggravated during winter by the topography and meteorological conditions of the city. Although public policies have been developed to minimise the atmospheric aerosol pollution, there is a lack of adequate knowledge and poor characterisation of these aerosols (in its PM_2.5 and PM₁₀ fractions). In this study we sampled atmospheric particles during winter in two distinct areas of Santiago: downtown (Teatinos Street) and in a more residential area (Macul). Major (Si, Al, Fe, Ca and K) and some trace element (S, Cl, Ti, P, Cr, Cu and Zn) compositions were obtained by proton-induced X-ray emission (PIXE). Morphological, type and chemical characterisation was also performed using scanning electron microscopy (SEM) coupled with an energy dispersive X-ray microanalysis system (SEM–EDX). Besides the carbon particles, the contribution of which can be quite important in the atmospheric aerosol, especially in downtown, unambiguously lithogenic (i.e. of geological origin) particles and elements are the second highest contributors. Enrichment factor calculation, together with particle identification and element correlation allow the origin of some elements and particles to be traced, revealing anthropogenic origins for some of them that are specific to the Santiago area.  相似文献   

Assessing the limits of the Modified Gaussian Model for remote spectroscopic studies of pyroxenes on Mars     

Lisa C. Kanner  John F. Mustard  Aline Gendrin 《Icarus》2007,187(2):442-456

We investigate the ability to refine pyroxene composition and modal abundance from laboratory and remotely acquired spectra. Laboratory data including the martian meteorites, Shergotty, Zagami, MIL03346, and ALH84001 as well as additional pyroxene-rich spectra obtained from the OMEGA (Observatoire pour la Minéralogie, l'Eau, les Glaces, et l'Activité) spectrometer for Mars are characterized using the Modified Gaussian Model (MGM), a spectral deconvolution method developed by Sunshine et al. [Sunshine, J.M., Pieters, C.M., Pratt, S., 1990. J. Geophys. Res. 95, 6955-6966]. We develop two sensitivity tests to assess the extent to which the MGM can consistently predict (1) pyroxene composition and (2) modal abundance for a compositionally diverse suite of pyroxene spectra. Results of the sensitivity tests indicate that the MGM can be appropriately applied to remote spectroscopic measurements of extraterrestrial surfaces and can estimate pyroxene composition and relative abundance within a derived uncertainty. Deconvolved band positions for laboratory spectra of the meteorites Shergotty and Zagami are determined within ±17 nm while remotely acquired OMEGA spectra are defined within ±50 nm. These results suggest that absolute compositions can be uniquely derived from laboratory pyroxene-rich spectra and non-uniquely derived from the remote measurements of OMEGA at this time. While relative pyroxene chemistries are not assessed from OMEGA measurements at this time, relative pyroxene abundances are estimated using a normalized band strength ratio between the low-calcium (LCP) and high-calcium (HCP) endmember components and are constrained to ±10%. The fraction of LCP in a two-pyroxene mixture is the derived value from the normalized band strength ratio, LCP/(LCP + HCP). This calculation for relative abundance is robust in the presence of up to 10-15% olivine. Deconvolution results from the OMEGA spectra indicate that the ancient terrain in the Syrtis Major region is uniquely enriched in LCP (59±10% LCP) relative to HCP while the volcanics of Syrtis Major are uniquely enriched in HCP (39±10% LCP).  相似文献   

Bentheimer sandstone revisited for experimental purposes     

《Marine and Petroleum Geology》2015

Bentheimer sandstone outcrop samples are ideal for laboratory studies due to their lateral continuity and block scale homogeneous nature. Over the years they have been used to investigate reservoir topics ranging from passive and active properties of oil/gas/water/rock interaction and processes to flow and transport.This work shows an evaluation of Bentheimer sandstone properties and their characteristics to advance understanding on the mineral accessory and the physical and electrical transport properties. On the basis of the nature of depositional environments and diagenesis, we measure and characterize spatial attributes of the matrix, mainly by qualitative analysis, laboratory and stereological measurements and statistical 2D/3D reconstructions. The main contribution of this paper is the impact of mineral composition on the petrophysical quality and block scale homogeneity of the reservoir. With 3D techniques reconstructions of the new rock grain framework pore structures have been created.Based on measurements, a review of literature data and interpretation of variation between the outcrops and flow relevant parameters, we conclude that Bentheimer sandstone is a rock that shows constant mineralogy and is largely free of paramagnetic impurities. In accordance with the results of 3D reconstructions techniques and in line with the depositional settings, they show a well sorted grain framework and a pore network that can be used to calculate the permeability and resistivity without conducting any direct laboratory measurements of either parameter. It presents a porosity with a range of 0.21–0.27 and permeabilities varying between 0.52 and 3.02 Darcy. Based on our work and literature, it is found that high permeability together with similar distribution of pore throats and bodies make the sandstone an attractive and easy obtainable candidate for comparative experimental studies. Moreover, we state by comparing various techniques that the efficiency and resolution accuracy of the applied method must be taken into consideration when planning the measurements.  相似文献   

Infrared micro-spectroscopy of the martian meteorite Zagami: Extraction of individual mineral phase spectra     

Ernesto Palomba  Alessandra Rotundi 《Icarus》2006,182(1):68-79

Zagami, a well characterized SNC meteorite, represents a reference sample to verify the feasibility of the non-destructive infrared micro-spectroscopy technique to extract spectral signatures from individual mineral phases in a meteorite sample. For the first time individual infrared spectra of the major mineral phases, in the 6000-600 cm⁻¹ (1.67-16.7 μm) spectral interval, whose identification is confirmed by energy dispersive X-ray analysis and backscattered imaging, are measured. The signatures of the main mineral phases we identified in the Zagami chip are: (1) maskelynite characterized by broad and smooth SiO vibrational bands in the 1000 cm⁻¹ spectral region; (2) crystalline pyroxenes showing well defined fine structures; and (3) an oxide mineral phase with an almost featureless and flat spectrum. In the part of the spectrum centered around 2 μm, by analyzing the different positions of the Fe²⁺ bands, we were able to discern the high-Ca from the low-Ca pyroxene phases. This result demonstrates that by means of the infrared micro-spectroscopy technique it is possible to retrieve directly the composition of pyroxenes in the En-Fs-Wo system, without relying on the use of deconvolution techniques. In addition IR signatures due to water and aliphatic hydrocarbons were observed to be more abundant in the pyroxenes than in maskelynite. This could be an indication that the organic and water signatures are due to indigenous compounds in Zagami rather than laboratory contamination, however, further investigations are necessary before this conclusion can be confirmed.  相似文献