柴达木盆地北缘第三系碎屑岩储层特征   总被引：7，自引：0，他引：7  

张成君  崔彦立等 《甘肃地质》2001,10(2):46-51

柴达木盆地北缘第三系有丰富的油气储集 ,主要存在于碎屑岩中 ,油气的储集明显与碎屑岩的沉积环境和成岩作用有关。对碎屑岩的储集空间和物性特征起直接的控制作用。通过分析碎屑岩的孔隙类型及在空间的分布特征 ,表明在早、晚成岩作用的转换带有大量的次生溶孔存在 ,是油气的有利富集区。储层物性与方解石成负相关 ,粘土矿物则有不同的变化趋势 ,伊利石的存在使物性变差。  相似文献   

Experimentelle Untersuchungen über den Einfluss einiger Zwei- und Dreiwertiger Metallkationen auf die Bildung und das Wachstum von CaCO₃: Experimental Study of the Influence of Some Divalent and Trivalent Metal Cations on Nucleation and Growth of CaCO₃     

Kai Zeppenfeld 《Chemie der Erde / Geochemistry》2003,63(3):264-280

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简论碳酸盐糜棱岩的岩石特征     

邵建波 《吉林地质》1992,11(2):55-60

韧性剪切带及糜棱岩的研究是当代地质科学的一项热门课题。而在地壳上广泛分布的碳酸盐岩石中的韧性剪切带的特征研究同样也具有重大意义。本文通过对碳酸盐矿物及岩变形机制和变形习惯的讨论,总结了碳酸盐糜棱岩的一些岩石特征,提出了在碳酸盐岩石中鉴定韧性剪切带的几项标志。  相似文献   

Elemental composition of calcites in late Quaternary pedogenic calcretes from Gujarat, western India     

Aniruddha S. Khadkikar 《Journal of Asian Earth Sciences》2005,25(6):893-902

Pedogenic calcretes commonly exhibit clotted micrite, circum-granular calcite (grain coats) and microspar/spar veins. The three calcite-types with different dimensions were analyzed for their magnesium content to determine the relationship between crystal elongation and magnesium incorporation. The results show a very low MgO content for grain coats and microspars and high values for clotted micrite indicating that the ideal kinetic model does not hold true and several variables govern the end composition of calcites. The magnesium concentrations of meteoric calcites are genetically linked to the evolutionary history of the soil and climate. Grain coats, which are elongated calcites, contain the least amount of Mg and is related to the initial stages of pedogenesis wherein the limiting factor is the Mg/Ca ratio of the parent fluid. Lower magnesium contents arise due to smaller quantities of Mg being released during incipient weathering. Micrite morphology and composition is controlled by the greater availability of Mg ions through weathering, higher pCO₂ in soil due to increased time-dependent soil respiration, which causes a rise in calcite precipitation rates and clay authigenesis. This in turn exerts a physical control on morphology by occluding pore space and providing numerous nuclei for calcite precipitation. The wide variability in spar cements is inherently controlled by inhomogeneties in parent fluid compositions with lower-than-micrite values on account of slower precipitation rates.  相似文献   

Mineralogy of primary carbonate-bearing hypabyssal kimberlite, Lac de Gras, Slave Province, Northwest Territories, Canada     

John P. Armstrong  Mark Wilson  Robert L. Barnett  Tom Nowicki  Bruce A. Kjarsgaard   《Lithos》2004,76(1-4):415-433

A suite of fresh, Late Cretaceous to Eocene hypabyssal kimberlites from the Lac de Gras field were studied in order to understand better carbonate, silicate and oxide paragenesis. The samples have excellent preservation of textures and primary mineralogy and are archetypal or Group 1 kimberlite. Five kimberlite localities are identified as calcite-bearing based on the presence of high Sr–Ba calcite as phenocrysts, microphenocrysts and in segregations. Three kimberlite localities are identified as dolomite-bearing based on the presence of mixed calcite–dolomite segregations containing oscillatory and banded textures of calcite–dolomite solid solution and dolomite (±magnesite). Sr–Ba calcite are characterized by high X_Ca (>0.95) and are enriched in Sr (4900–11,100 ppm) and Ba (3200–14,200 ppm). The calcite–dolomite and dolomite–magnesite solid solution compositions span the X_Ca range from 0.42 to 0.95, and typically have Sr and Ba contents in the range of 1000–4000 ppm. The carbonate, silicate and oxide mineral compositions suggest that the origin of the calcite-bearing versus dolomite-bearing kimberlites studied is related to subtle differences in parent magma composition, in particular, the CO₂/H₂O ratio. Formation of the carbonates reflects the latter part of a protracted magmatic crystallization sequence, in which Sr–Ba calcite precipitates from an evolved kimberlite melt. Subsequently, calcite–dolomite solid solution and dolomite is precipitated from localized, Mg-rich carbonate fluids at relatively high temperatures (higher than serpentine stability).  相似文献   

Strain investigations on calcite marbles using neutron time-of-flight diffraction     

C. Scheffzük  S. Siegesmund  A. Koch 《Environmental Geology》2004,46(3-4):468-476

In order to describe and explain the effect of bowing of marble facade panels, neutron time-of-flight diffraction was applied to determine residual macro- and microstrain on the calcite mineral phase. The measurements were combined with investigations of the crystallographic preferred orientation (texture) measurements by neutron diffraction, macroscopic measuring of the bowing on marble building stones, as well as microfabric analyses. Three samples were investigated to explain the bowing effect: a fresh broken sample, a good conditioned facade panel and a strongly deformed facade panel. Residual intracrystalline strain was detected in all investigated samples, which differed in the degree of bowing. For the first time, the preferred orientation and the residual strain were found to be related. The results show that different strain magnitudes are reflected by residual strains, which differ significantly in magnitude and direction. Furthermore, different Bragg peak widths have been detected as an indication of microscopic strain. The observed residual strain values in the samples are related with the grain shape and texture properties.  相似文献   

Experimental Research on Microscopic Indicators of Temperature's Returning-to-Zero in Deformation of Calcite and Discussions of Correlation Problem     

Yao Daquan 《中国地震研究》2005,19(1):35-42

1 RESEARCHINTOTHEACTIVITYTIMEOFFAULTSINBEDROCKAREASDatemeasurementoffaultactivityisessentialforrecognizingtheactivitybehaviorofafault,inversingseismologicalandgeologicaleventsandprobingintoearthquakerhythms .Itismoredifficulttodeterminetheactivitytimeoffa…  相似文献   

Removal of trace elements from landfill leachate by calcite precipitation   总被引：1，自引：0，他引：1  

Vojtch Ettler  Olga Zelen  Martin Mihaljevi   Ond&#x;ej &#x;ebek  Ladislav Strnad  Pavel Coufal  Petr Bezdi ka 《Journal of Geochemical Exploration》2006,88(1-3):28

Spontaneous precipitation of secondary calcite (CaCO₃) has been observed in 25 samples of landfill leachate-polluted stream waters. During the 6-month precipitation experiment, the formation of calcite acts as a principal trace-element scavenging process. The concentrations of Fe, Sr, Ba and Mn and other trace elements in solution significantly decreased as calcite formed during the experiments. The PHREEQC-2 geochemical code indicated high supersaturation of the initial leachate-polluted waters with respect to calcite. The chemical/mineralogical study (SEM/EDS, XRD, ICP MS) revealed that this newly formed calcite contains considerable amounts of metals and metalloids removed from solution. Such a geochemical process can be considered to be important for spontaneous decontamination in landfill-affected environments (stream sediments, soils) or landfill technical facilities (settling basins). This removal takes place especially during dry periods with low rain precipitation, when the landfill waters exhibit both higher alkalinity and higher trace element concentrations.  相似文献   

Effectiveness of various dispersed alkaline substrates for the pre-treatment of ferriferous acid mine drainage     

《Applied Geochemistry》2016

Dispersed alkaline substrates (DAS) have been successfully used in passive treatment of highly contaminated acid mine drainage (AMD) to limit coating and clogging issues. However, further optimization of DAS systems is still needed, especially for their long-term efficiency during the treatment of ferriferous AMD. In the present study, three types of DAS comprised of natural alkaline materials (wood ash, calcite, dolomite), in different proportions (20%v/v, 50%v/v, 80%v/v), and a substrate with high surface area (wood chips) were tested in 9 batch reactors. The testing was carried out, in duplicate, for a period of 91 days, to evaluate the comparative performance of the mixtures for iron pre-treatment in ferriferous AMD (2500 mg/L Fe, at pH 4). Results showed increasing of pH (between 4.15 and 7.12), regardless of the proportion of alkaline materials in the DAS mixtures. Among the tested mixtures, wood ash type DAS were more effective for Fe removal (99.9%) than calcite or dolomite type DAS (up to 66%). All tested DAS had limited efficiency for sulfate removal and an additional treatment unit, such as a sulfate-reducing biochemical reactor, is needed. Moreover, due to the similar performances of the calcite and dolomite DAS, they could be potentially substituted and rather be used in a polishing treatment unit. Based on these findings, the most promising mixture was the 50% wood ash type DAS (WA50-DAS).  相似文献   

Dedolomitization and calcite cementation in the Middle Devonian Winnipegosis Formation in Central Saskatchewan,Canada     

QILONG FU  HAIRUO QING  KATHERINE M. BERGMAN  CHAO YANG 《Sedimentology》2008,55(6):1623-1642

Limestone consisting of finely to medium crystalline calcite mosaics is present in the upper part of the Winnipegosis Formation on the east‐central margin of the Elk Point Basin where the overlying Prairie Evaporite deposits have been removed. This type of crystalline limestone is interpreted as dedolomite, based on petrographic observations. The δ¹⁸O and δ¹³C values of the Winnipegosis dedolomite vary from ?12·8‰ to ?11·9‰ VPDB (Vienna Pee Dee Belemnite) and from ?0·5‰ to +1·7‰ VPDB, respectively; both values are significantly lower than those for the corresponding dolomite. The ⁸⁷Sr/⁸⁶Sr ratios of the dedolomite are significantly higher, between 0·7082 and 0·7087. The spatial distribution and geochemical data of the Winnipegosis dedolomite suggest that dedolomitization was related to an influx of fresh groundwater and dissolution of the Prairie Evaporite anhydrite during the latest Mississippian to the Early Cretaceous when the basin was subjected to uplift and erosion. The Winnipegosis dedolomite displays a series of replacement fabrics showing progressive calcitization of dolomite, including the occurrence of dedolomite restricted along fractures and adjacent areas, dolomite patches ‘floating’ in the dedolomite masses and massive dedolomite with sparsely scattered dolomite relicts. However, the characteristic fabrics resulting from dedolomitization documented in the literature have not been observed in the Winnipegosis dedolomite. Coarsely to very coarsely crystalline, subhedral to euhedral calcite cement is restricted in the dedolomite. The petrographic features, isotopic compositions and homogenization temperatures, coupled with the burial history of the Winnipegosis Formation, constrain the precipitation of the calcite cement from a mixing of basinal brines and fresh groundwater during Late Cretaceous to Neogene time. The more negative C‐isotopic signatures of the calcite cement (?5·3‰ to ?2·3‰ VPDB) probably reflect a hydrocarbon‐derived carbon.  相似文献