Origin,organic geochemistry,and estimation of the generation potential of Neogene lacustrine sediments from the Valjevo-Mionica Basin,Serbia     

A. Sajnović  K. Stojanović  G. S. Pevneva  A. K. Golovko  B. Jovančičević 《Geochemistry International》2010,48(7):678-694

This paper reports an investigation of 60 samples of lacustrine sedimentary rocks of Neogene age lying at depths of 0–400 m in the Valjevo-Mionica Basin, Serbia. The goal of the study was to determine the origin and type of primary organic matter (OM), the degree of thermal alteration, the generation potential of OM from the rocks of this basin, and conditions in the sedimentation environment during the formation of the rocks. The potential of OM of the rocks was estimated on the basis of the thermolysis of a representative sample after its preliminary debituminization.  相似文献   

Fabric transpositions in granite plutons — An insight from non-scaled analogue modelling     

Zuzana Kratinová  Matej Machek  Vladimír Kusbach 《Journal of the Geological Society of India》2010,75(1):267-277

Investigations on a set of experimental models of highly viscous intrusions were carried out in order to study the internal strain pattern during vertical ascent and emplacement of granite intrusions. The strain pattern was determined by means of anisotropy of magnetic susceptibility (AMS) resulting from the orientation of magnetite particles in a liquid plaster medium. The modelled intrusions show distinct fabrics reflecting the flow of a rheologically complex, non-Newtonian material. During the vertical growth of the intrusion, constrictional vertical fabrics are transposed into flattening fabrics, and along with the development of low-intensity fabric domains are passively transported upwards. Vertical growth takes place along subvertical thrust shear zones that satisfactorily explain the discordant magmatic fabrics in granites along intrusion sides. The resulting complex fabric patterns suggest that the vertical movement of material in ascending intrusions is accommodated by various flow mechanisms operating simultaneously.  相似文献   

硅藻提纯方法新进展:小个体硅藻纯化的实验技术          下载免费PDF全文

李东  汉景泰  孙会国  董明  富永红 《第四纪研究》2010,30(3)

硅藻壳体氧同位素是近年来发展起来的一种重要的古气候研究手段[1～3],硅藻的分离提纯是开展此项研究的重要一环.矿物杂质由于与硅藻壳体的氧同位素差异很大[1,4,5],对目前常用的硅藻氧同位素实验方法[1,4]获得的结果有显著影响.  相似文献   

Sulfur isotope variations from orebody to hand-specimen scale at the Mežica lead–zinc deposit, Slovenia: a predominantly biogenic pattern     

Uroš Herlec  Jorge E. Spangenberg  Jošt V. Lavrič 《Mineralium Deposita》2010,45(6):531-547

The Mississippi Valley-type (MVT) Pb–Zn ore district at Mežica is hosted by Middle to Upper Triassic platform carbonate rocks in the Northern Karavanke/Drau Range geotectonic units of the Eastern Alps, northeastern Slovenia. The mineralization at Mežica covers an area of 64 km² with more than 350 orebodies and numerous galena and sphalerite occurrences, which formed epigenetically, both conformable and discordant to bedding. While knowledge on the style of mineralization has grown considerably, the origin of discordant mineralization is still debated. Sulfur stable isotope analyses of 149 sulfide samples from the different types of orebodies provide new insights on the genesis of these mineralizations and their relationship. Over the whole mining district, sphalerite and galena have δ ³⁴ S values in the range of –24.7 to –1.5‰ VCDT (–13.5 ± 5.0‰) and –24.7 to –1.4‰ (–10.7 ± 5.9‰), respectively. These values are in the range of the main MVT deposits of the Drau Range. All sulfide δ ³⁴ S values are negative within a broad range, with δ ³⁴ S _pyrite <δ ³⁴ S _sphalerite <δ ³⁴ S _galena for both conformable and discordant orebodies, indicating isotopically heterogeneous H₂S in the ore-forming fluids and precipitation of the sulfides at thermodynamic disequilibrium. This clearly supports that the main sulfide sulfur originates from bacterially mediated reduction (BSR) of Middle to Upper Triassic seawater sulfate or evaporite sulfate. Thermochemical sulfate reduction (TSR) by organic compounds contributed a minor amount of ³⁴S-enriched H₂S to the ore fluid. The variations of δ ³⁴ S values of galena and coarse-grained sphalerite at orefield scale are generally larger than the differences observed in single hand specimens. The progressively more negative δ ³⁴ S values with time along the different sphalerite generations are consistent with mixing of different H₂S sources, with a decreasing contribution of H₂S from regional TSR, and an increase from a local H₂S reservoir produced by BSR (i.e., sedimentary biogenic pyrite, organo-sulfur compounds). Galena in discordant ore (–11.9 to –1.7‰; –7.0 ± 2.7‰, n = 12) tends to be depleted in ³⁴ S compared with conformable ore (–24.7 to –2.8‰, –11.7 ± 6.2‰, n = 39). A similar trend is observed from fine-crystalline sphalerite I to coarse open-space filling sphalerite II. Some variation of the sulfide δ ³⁴ S values is attributed to the inherent variability of bacterial sulfate reduction, including metabolic recycling in a locally partially closed system and contribution of H₂S from hydrolysis of biogenic pyrite and thermal cracking of organo-sulfur compounds. The results suggest that the conformable orebodies originated by mixing of hydrothermal saline metal-rich fluid with H₂S-rich pore waters during late burial diagenesis, while the discordant orebodies formed by mobilization of the earlier conformable mineralization.  相似文献   

Corrigendum to “Petrogenesis of the Late Cretaceous Demirköy Igneous Complex in the NW Turkey: Implications for magma genesis in the Strandja Zone” [Lithos 114 (2010), 369–384]     

Zekiye Karacık  Okan Tüysüz 《Lithos》2010,117(1-4):331

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高强度模拟酸雨量对珠三角地区潮土中重金属元素释放的影响     

李展强  杨晓艳  莫书伟  陈福强 《岩矿测试》2010,29(2):136-138

采用平均离子强度下30年雨量的模拟酸雨淋滤珠江三角洲潮土,电感耦合等离子体质谱法测定重金属元素,研究潮土0~90 cm处各节土壤柱中重金属镉、钴、铜、锌、铅、砷、钛、钒、铬、锰等元素的释放情况。研究表明,在高强度模拟酸雨淋滤下,潮土中重金属元素的释放情况存在较大差异。长期的酸雨淋滤,土壤中的镉、钴、铜、锌和铅在不同深度均有不同程度的淋失;砷、钛、钒、铬、锰等元素不会造成大量的淋失。利用这种差异可以评估重金属元素对环境的潜在影响,为农田生态系统的预警预测提供依据。  相似文献   

Heat capacity, entropy, and magnetic properties of jarosite-group compounds     

Juraj Majzlan  Peter Glasnák  Robert A. Fisher  Mary Anne White  Michel B. Johnson  Brian Woodfield  Juliana Boerio-Goates 《Physics and Chemistry of Minerals》2010,37(9):635-651

Jarosite phases are common minerals in acidic, sulfate-rich environments. Here, we report heat capacities (C _p) and standard entropies (S°) for a number of jarosite samples. Most samples are close to the nominal composition AFe₃(SO₄)₂(OH)₆, where A = K, Na, Rb, and NH₄. One of the samples has a significant number of defects on the Fe sites and is called the defect jarosite; others are referred to as A-jarosite. The samples, their compositions, and the entropies at T = 298.15 K are:

Sample	Chemical composition	S o/(J mol−1 K−1)
K-jarosite	K0.92(H3O)0.08Fe2.97(SO4)2(OH)5.90(H2O)0.10	427.4 ± 0.7
Na-jarosite	Na0.95(H3O)0.05Fe3.00(SO4)2(OH)6.00	436.4 ± 4.4
Rb-jarosite	RbFe2.98(SO4)2(OH)5.95(H2O)0.05	411.9 ± 4.1
NH4-jarosite	(NH4)0.87(H3O)0.13Fe3.00(SO4)2(OH)6.00	447.2 ± 4.5
Defect jarosite	K0.94(H3O)0.06Fe2.34(SO4)2(OH)4.01(H2O)1.99	412.7 ± 4.1

There are additional configurational entropies of 13.14 and 8.23 J mol⁻¹ K⁻¹ in defect and NH₄-jarosite, respectively. A detailed analysis of the synchrotron X-ray diffraction patterns showed a large anisotropic peak broadening for defect and NH₄-jarosite. The fits to the low-temperature (approx. <12 K) C _p data showed that our samples can be divided into two groups. The first group is populated by the K-, Na-, Rb-, and NH₄-jarosite samples, antiferromagnetic at low temperatures. The second group contains the H₃O-jarosite (studied previously) and the defect jarosite. H₃O- and defect jarosite are spin glasses and their low-T C _p was fit with the expression C _p = γT + ΣB _j T _j , where j = (3, 5, 7, 9). The linear term is typical for spin glasses and the sum represents the lattice contribution to C _p. Surprisingly, the C _p of the K-, Na-, Rb-, and NH₄-jarosite samples, which are usually considered to be antiferromagnetic at low temperatures, also contains a large linear term. This finding suggests that even these phases do not order completely, but have a partial spin-glass character below their Néel transition temperature.  相似文献   

The use of a finite mixture distribution model in bottled water characterisation and authentication with stable hydrogen,oxygen and carbon isotopes — Case study from Slovenia     

Mihael Brenčič  Polona Vreča 《Journal of Geochemical Exploration》2010

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海南岛三叠纪中基性岩的年代学、地球化学及其地质意义   总被引：1，自引：0，他引：1       下载免费PDF全文

唐立梅  陈汉林  董传万  沈忠悦  程晓敢  付璐露 《地质科学》2010,45(4):1139-1155

辉长岩大多为地幔岩石部分熔融的产物,辉绿岩脉及碱性正长岩的形成通常与伸展构造有关,本文对海南岛万宁辉长岩及辉绿岩脉和分界洲正长岩进行了系统的年代学和岩石地球化学研究,并以此来讨论其构造意义。LA-ICP-MS锆石U-Pb定年结果表明,万宁辉长岩及辉绿岩脉形成约在240 Ma,分界洲正长岩形成约在231 Ma,主量元素特征表明万宁辉长岩和辉绿岩分别属碱性系列和亚碱性系列,分界洲正长岩属于典型的碱性岩浆岩。万宁辉长岩及辉绿岩脉的稀土元素具有轻稀土富集的特点(LREE/HREE=7.22～8.50和8.11～11.10),微量元素具有岛弧型火山岩的特征,富集大离子亲石元素K、Rb、Ba、Th,贫高场强元素Nb、Ta和Zr、Hf;分界洲正长岩的微量元素特征显示出与A型花岗岩类似的特征。海南岛三叠纪中基性岩如分界洲正长岩和万宁辉长岩及辉绿岩脉形成的构造背景为陆内伸展环境,指示海南岛在240～230 Ma处于印支造山运动的应力松弛阶段。  相似文献   

Reduction of surface subsidence risk by fly ash exploitation as filling material in deep mining areas   总被引：1，自引：1，他引：0  

Trčková Jiřina  Šperl Jan 《Natural Hazards》2010,53(2):251-258

The possibility of filling empty underground spaces, which exist owing to the extraction of mineral raw materials, with fly ash and cement fly ash mixes has been studied for the purpose of reducing the impact of deep mining on the surface. The method of physical modelling was used to study the behaviour of fly ash mixes deposited in extracted mine spaces. The models were constructed for two different geometries of underground extracted mine spaces: into cavities of the type of large slits created in the course of mining in steeply lode deposits without subsequently filling the empty space and in vertical shafts of rectangular or circular cross-section with horizontal side headings that have partly caved in due to mine shocks or other seismic events.  相似文献