Tectonic setting and petrogenesis of the Çelebi granitoid, (Kırıkkale-Turkey) and comparison with world skarn granitoids     

《Journal of Geochemical Exploration》2002,76(3)

Many studies have shown systematic correlations between the composition of plutons worldwide and the metal content of associated skarns. This is the first report of similar correlations between the composition of Çelebi granitoid and skarns of the Çelebi district in Central Anatolia, Turkey. The Çelebi district is well known for its polymetallic Fe–W and Cu vein ores. These are hosted by calcic skarn zones. Both exoskarns (pyroxene–garnet) and endoskarns (epidote–pyroxene) occur in the district formed mainly along the granitoid contacts and along the fractures within the marble. Based on mineralogy, petrology and geochemistry, two different igneous rocks were recognized in the Çelebi granitoid, referred to as leucocratic (felsic) and mesocratic (intermediate) Çelebi granitoid. The leucocratic Çelebi occurs as dominant rock type, and is classified as granite. The mesocratic Çelebi is not widespread and is classified as adamellite, tonalite, quartz monzonite and quartz monzodiorite. The mesocratic Çelebi has I-type characteristics, and have subalkaline, calc-alkaline and metaluminous characteristics like most worldwide skarn granitoids.A post-collisional tectonic setting is proposed on the basis of field evidence, the relative timing of intrusions with respect to metamorphic and obducted ophiolitic rocks and trace element geochemistry. The high abundance of La and Ce and the enrichment of V in mafic components suggest that Çelebi granitoids are formed by partial melting of mantle rocks, but have been contaminated by interaction with continental crust involving possible magma mixing processes (i.e. mixing of coexisting felsic and mafic magmas). In the district, the mesocratic type and mafic microgranular enclaves (MME) mainly within leucocratic type represent a mafic underplating magma that was mixed with and/or injected into felsic magma of the leucocratic type.The present study shows that Fe mineralization is associated with mesocratic Çelebi type, whereas W mineralization is associated with leucocratic type. Mesocratic Çelebi granitoid is significantly different from the worldwide average of plutons associated with Fe skarns. In particular, MgO vs. SiO₂, FeOt+CaO+Na₂O/K₂O vs. SiO₂, Fe₂O₃/Fe₂O₃+FeO vs. SiO₂ and V vs. Ni vary from typical values (are lower than values typical for plutons associated with Fe skarns) for plutons associated with Fe skarns. Instead, it resembles the geochemical characteristics of plutons associated with worldwide Cu and possibly Au skarns. This suggests new exploration possibilities for copper and gold in the Çelebi district.  相似文献   

Low-temperature thermodynamic properties of disordered zeolites of the natrolite group     

I. E. Paukov  N. K. Moroz  Yu. A. Kovalevskaya  I. A. Belitsky 《Physics and Chemistry of Minerals》2002,29(4):300-306

 The heat capacity of paranatrolite and tetranatrolite with a disordered distribution of Al and Si atoms has been measured in the temperature range of 6–309 K using the adiabatic calorimetry technique. The composition of the samples is represented with the formula (Na_1.90K_0.22Ca_0.06)[Al_2.24Si_2.76O₁₀]·nH₂O, where n=3.10 for paranatrolite and n=2.31 for tetranatrolite. For both zeolites, thermodynamic functions (vibrational entropy, enthalpy, and free energy function) have been calculated. At T=298.15 K, the values of the heat capacity and entropy are 425.1 ± 0.8 and 419.1 ±0.8 J K⁻¹ mol⁻¹ for paranatrolite and 381.0 ± 0.7 and 383.2 ± 0.7 J K⁻¹ mol⁻¹ for tetranatrolite. Thermodynamic functions for tetranatrolite and paranatrolite with compositions corrected for the amount of extraframework cations and water molecules have also been calculated. The calculation for tetranatrolite with two water molecules and two extraframework cations per formula yields: C _p (298.15)=359.1 J K⁻¹ mol⁻¹, S(298.15) −S(0)=362.8 J K⁻¹ mol⁻¹. Comparing these values with the literature data for the (Al,Si)-ordered natrolite, we can conclude that the order in tetrahedral atoms does not affect the heat capacity. The analysis of derivatives dC/dT for natrolite, paranatrolite, and tetranatrolite has indicated that the water- cations subsystem within the highly hydrated zeolite may become unstable at temperatures above 200 K. Received: 30 July 2001 / Accepted: 15 November 2001  相似文献   

华北地台北缘成矿带大青山绿岩型金矿地质特征     

杨补旺  李四娃  崔来旺 《内蒙古地质》2002,(1)

本文详细阐述了大青山地区绿岩型金矿的地质特征和找矿标志,指出金矿化带赋存在二道洼群大理岩与其它岩层的接触部位,同时受韧性剪切带控制,在大理岩褶曲部位或下层位有利于形成较富矿体。该类型金矿的发现,大大地拓展了在大青山地区的找矿空间。  相似文献   

在"数字国土工程"中我区地学数据库建设的现状及发展趋势     

张梅  胡凤翔 《内蒙古地质》2002,(2)

近年来,在国土资源部的高度重视下,我区相继建立了一系列地学数据库。这些地学数据库的建立不仅为地矿行业提供了基础性数据,也加速了"数字国土工程"和国土资源信息化建设的步伐。随着信息技术的高速发展,利用地理信息系统(GIS)将各类地学数据有机地结合起来,形成地学数据应用与管理系统,最终通过网络服务于社会,必将是各类地学数据发展的必然趋势。  相似文献   

Analysis and simulation of magma mixing processes in 3D   总被引：2，自引：0，他引：2  

D. Perugini  G. Poli  G. D. Gatta 《Lithos》2002,65(3-4):313-330

Magma mixing structures from the lava flow of Lesbos (Greece) are analyzed in three dimensions using a technique that, starting from the serial sections of rock cubes, allows the reconstruction of the spatial distribution of magmas inside rocks. Two main kinds of coexisting structures are observed: (i) “active regions” (AR) in which magmas mix intimately generating wide contact surfaces and (ii) “coherent regions” (CR) of more mafic magma that have a globular shape and do not show large deformations. The intensity of mingling is quantified by calculating both the interfacial area (IA) between interacting magmas and the fractal dimension of the reconstructed structures. Results show that the fractal dimension is linearly correlated with the logarithm of interfacial area allowing discrimination among different intensities of mingling.

The process of mingling of magmas is simulated using a three-dimensional chaotic dynamical system consisting of stretching and folding processes. The intensity of mingling is measured by calculating the interfacial area between interacting magmas and the fractal dimension, as for natural magma mixing structures. Results suggest that, as in the natural case, the fractal dimension is linearly correlated with the logarithm of the interfacial area allowing to conclude that magma mixing can be regarded as a chaotic process.

Since chemical exchange and physical dispersion of one magma inside another by stretching and folding are closely related, we performed coupled numerical simulations of chaotic advection and chemical diffusion in three dimensions. Our analysis reveals the occurrence in the same system of “active mixing regions” and “coherent regions” analogous to those observed in nature. We will show that the dynamic processes are able to generate magmas with wide spatial heterogeneity related to the occurrence of magmatic enclaves inside host rocks in both plutonic and volcanic environments.  相似文献   

Gold Occurrence and Ore Genesis,Yata Micro—Disseminated Gold Deposit,Guizhou,Southwest China     

朱笑青  王中刚 《中国地球化学学报》2002,21(4):370-373

The mode of occurrence of gold in the Yata micro-disseminated gold deposit is ap-proached through chemical phase studies coupled with ore-dressing monitoring and micro-beam analysis.The results showed that gold occurred for the most part as ultra-microscopic particles adsorbed on the surfaces or fracture planes of pyrite and other sulphides.The proportions of gold of different occurrences were estimated solutions containing nanometer-sized gold particles were prepared following the hydrolysis-reduction procedure and the adsorption of nanometer-sized gold on ordinary sulphides and rocks was experimentally determined.It is evident that sulphides are good adsorbents of gold and this is consistent with geological observations.  相似文献   

REE Geochemistry of the Lead—Zinc Ores from the Jinding Lead—Zinc Deposit,Lanping,Yunnan   总被引：3，自引：1，他引：3  

牟传龙  余谦  张立生 《中国地球化学学报》2002,21(1):57-64

Nineteen volcanic and magmatic rock samples were collectecd from the Jinding leadzinc deposit and its surrounding areas in Yunnan.The ICP and AES analyses,feferred to the previous results,show that the metal minerals and altered rocks in the Jinding lead-zinc deposit display a decreasing trend of ∑REE from the early to late stages of mineralization,and similarities in REE distribution patterns,indicating that the ore fluids are characterized by high LREE enrichment,markedly negative δCe anomaly and slight δEu anomaly.These REE distribution paterns exhibit striking similarities to those of the Pliocene trachyte in the study area,both of which are similar in ∑REE,LREE/HREE ratio,δEu and δCe.The ore fluids besides the basin fluids in the deposit are also closely related to those associated with Pliocene trachyte magmas.  相似文献   

Geochemical Studies of Sodium Enriched Metavolcanite Series in the Area of Longbohe Copper Deposit,Yunnan Province,SW China：Nd,Sr and Pb Isotopic Characteristics and Chronology     

常向阳  朱炳泉  莫向云 《中国地球化学学报》2002,21(2):163-169

The chronological data obtained by a variety of dating methods have confirmed that the sodium enriched metavolcanite series in the area of the Longbohe copper deposit at Jinping, Yunnan Province, was formed during the Proterozoic (its Pb−Pb isochron age=1595±75 Ma), corresponding to the Dahongshan Group sodium enriched metavolcanites. The Sm−Nd isochron age of 1336±46Ma should represent the time at which this series of volcanic rocks experienced spilitization in response to sodium metasomatism, equivalent to the time of sedimentation of the Ailaoshan Group and Yashan Group rocks. The Rb−Sr ages of the volcanic rocks and the Pb−Pb ages of copper ores have recorded the events of strong dynamic metamorphism and of strong reworking-metallogenesis of copper during the Jinningian period. Similarities in forming age, rock assemblage and isotopic characteristics between the sodium enriched metavolcanite series and the Dahongshan Group sodium enriched metavolcanite series have provided new clues to the exploration of the Dahongshan-type copper deposits in this area. Granted jointly by the National Natural Science Foundation of China (Nos. 49702022, 40073001) and the State 973 Program (No. G1999043215).  相似文献   

Rare earth elements in waters from the albitite-bearing granodiorites of Central Sardinia, Italy   总被引：1，自引：0，他引：1  

Riccardo BiddauRosa Cidu  Franco Frau 《Chemical Geology》2002,182(1):1-14

With the aim of contributing to the knowledge of the geochemical behaviour and mobility of the rare earth element (REE) in the natural water systems, the ground and surface waters of the Ottana-Orani area (Central Sardinia, Italy) were sampled. The study area consists of albititic bodies included in Hercynian granodiorites. The waters have pH in the range of 6.0-8.6, total dissolved solid (TDS) of between 0.1 and 0.6 g/l, and major cation composition dominated by Ca and Na, whereas predominant anions are Cl and/or HCO₃.The pH and the major-element composition of the waters are the factors affecting the concentration of REE in solution. The concentrations of ∑REE+Y in the samples filtered at 0.4 μm vary between 140 and 1600 ng/l, with La of between 14 and 314 ng/l, and Yb of between <6 and 12 ng/l. A negative Ce anomaly, especially marked at high pH, is observed in the groundwaters. The surface waters show lower REE concentrations, which are independent of pH, and negligible Ce anomaly.Speciation calculations, carried out with the EQ3NR computer program, showed that the complexes with the CO₃²⁻ ligand are the dominant REE species at pH in the range of 6.7-8.6. The REE³⁺ ions dominate the speciation at pH <6.7 and only in the light REE (LREE).The relative concentrations of REE in water roughly reflect those in the aquifer host rocks. However, when concentrations of REE in water are normalised relative to the parent rocks, a preferential fractionation of heavy REE (HREE) into the water phase can be observed, suggesting the greater mobility and stability of HREE in aqueous solution.  相似文献   

油压夯管锤蓄能器与活塞振动耦合性的数学解析          下载免费PDF全文

李国民 《探矿工程》2002,(1):52-54

蓄能器容积的变化与夯管锤的工作过程是紧密联系在一起的，由于活塞的前后运动以及在运动过程中的每一时刻所需要的油量不同的，理想状态就要通过蓄能器的容积变化来调节，就是说蓄能器的容积变化要与夯管锤的冲击振动相耦合。简要介绍了油压夯管锤结构原理，分别解释了油压夯管锤蓄能器与夯管锤的容积压力耦合。  相似文献