Heating duration of igneous rim formation on a chondrule in the Northwest Africa 3118 CV3oxA carbonaceous chondrite inferred from micro-scale migration of the oxygen isotopes     

《Chemie der Erde / Geochemistry》2019,79(4):125524

Due to their common occurrence in various types of chondrites, igneous rims formed on pre-existing chondrules throughout chondrule-forming regions of the solar nebula. Although the peak temperatures are thought to reach similar values to those achieved during chondrule formation events, the heating duration in chondrule rim formation has not been well defined. We determined the two-dimensional chemical and oxygen isotopic distributions in an igneous rim of a chondrule within the Northwest Africa 3118 CV3_oxA chondrite with sub-micrometer resolution using secondary ion mass spectrometry and scanning electron microscopy. The igneous rim experienced aqueous alteration on the CV parent body. The aqueous alteration resulted in precipitation of the secondary FeO-rich olivine (Fa_40–49) and slightly disturbed the Fe-Mg distribution in the MgO-rich olivine phenocrysts (Fa_11–22) at about a 1 μm scale. However, no oxygen isotopic disturbances were observed at a scale greater than 100 nm. The MgO-rich olivine, a primary phase of igneous rim formation, has δ¹⁷O = −6 ± 3‰ and δ¹⁸O = −1 ± 4‰, and some grains contain extreme ¹⁶O-rich areas (δ¹⁷O, δ¹⁸O = ∼−30‰) nearly 10 μm across. We detected oxygen isotopic migration of approximately 1 μm at the boundaries of the extreme ¹⁶O-rich areas. Using oxygen self-diffusivity in olivine, the heating time of the igneous rim formation could have continued from several hours to several days at near liquidus temperatures (∼2000 K) in the solar nebula suggesting that the rim formed by a similar flash heating event that formed the chondrules.  相似文献   

Phosphate removal from water by naturally occurring shale,sandstone, and laterite: The role of iron oxides and of soluble species     

Dan Eude Kpannieu  Martine Mallet  Lacina Coulibaly  Mustapha Abdelmoula  Christian Ruby 《Comptes Rendus Geoscience》2019,351(1):37-47

Aqueous phosphate removal by three geomaterials from Ivory Coast was evaluated to determine their potential application as low-cost phosphate adsorbents in wastewater treatment. Batch experiments showed that phosphate uptake strongly depended on pH. Laterite and sandstone dissolution was less pronounced compared to shale. A correlation between concentrations of aqueous cation species released from shale and phosphate uptake was observed. The kinetics were well described using the pseudo-second-order model. Isotherms displayed a saturation level on shale, while phosphate uptake continuously increased for laterite and sandstone. The removal efficiency decreased in the following ranking order: laterite > sandstone > shale. Laterite was also the most efficient adsorbent in column experiments. The high phosphate removal efficiency of laterite (8.3 mg PO₄ g^?1) was attributed to the presence of superparamagnetic low grain sizes of goethite. Laterite is a particularly promising material for further investigation in wastewater treatment technology such as constructed wetlands.  相似文献   

Biogeochemistry of dissolved carbon,major, and trace elements during spring flood periods on the Ob River     

Sergey N. Vorobyev  Oleg S. Pokrovsky  Larisa G. Kolesnichenko  Rinat M. Manasypov  Liudmila S. Shirokova  Jan Karlsson  Sergey N. Kirpotin 《水文研究》2019,33(11):1579-1594

Detailed knowledge of the flood period of Arctic rivers remains one of the few factors impeding rigorous prediction of the effect of climate change on carbon and related element fluxes from the land to the Arctic Ocean. In order to test the temporal and spatial variability of element concentration in the Ob River (western Siberia) water during flood period and to quantify the contribution of spring flood period to the annual element export, we sampled the main channel year round in 2014–2017 for dissolved C, major, and trace element concentrations. We revealed high stability (approximately ≤10% relative variation) of dissolved C, major, and trace element concentrations in the Ob River during spring flood period over a 1‐km section of the river channel and over 3 days continuous monitoring (3‐hr frequency). We identified two groups of elements with contrasting relationship to discharge: (a) DIC and soluble elements (Cl, SO₄, Li, B, Na, Mg, Ca, P, V, Cr, Mn, As, Rb, Sr, Mo, Ba, W, and U) negatively correlated (p < 0.05) with discharge and exhibited minimal concentrations during spring flood and autumn high flow and (b) DOC and particle‐reactive elements (Al, Fe, Ti, Y, Zr, Nb, Cs, REEs, Hf, Tl, Pb, and Th), some nutrients (K), and metalloids (Ge, Sb, and Te), positively correlated (p < 0.05) with discharge and showed the highest concentrations during spring flood. We attribute the decreased concentration of soluble elements with discharge to dilution by groundwater feeding and increased concentration of DOC and particle‐reactive metals with discharge to leaching from surface soil, plant litter, and suspended particles. Overall, the present study provides first‐order assessment of fluxes of major and trace elements in the middle course of the Ob River, reveals their high temporal and spatial stability, and characterizes the mechanism of river water chemical composition acquisition.  相似文献   

Geochemistry of Flooded Underground Mine Workings Influenced by Bacterial Sulfate Reduction     

Amber J. Roesler  Christopher H. Gammons  Gregory K. Druschel  Harry Oduro  Simon R. Poulson 《Aquatic Geochemistry》2007,13(3):211-235

Unlike the majority of the water in the flooded mine complex of Butte Montana, which includes the highly acidic Berkeley pit lake, groundwater in the flooded West Camp underground mine workings has a circum-neutral pH and contains at least 8 μM aqueous sulfide. This article examines the geochemistry and stable isotope composition of this unusual H₂S-rich mine water, and also discusses problems related to the colorimetric analysis of sulfide in waters that contain FeS_(aq) cluster compounds. The West Camp mine pool is maintained at a constant elevation by continuous pumping, with discharge water that contains elevated Mn (90 μM), Fe (16 μM), and As (1.3 μM) but otherwise low metal concentrations. Dissolved inorganic carbon in the mine water is in chemical and isotopic equilibrium with rhodochrosite in the mineralized veins. The mine water is under-saturated with mackinawite and amorphous FeS, but is supersaturated with Cu- and Zn-sulfides. However, voltammetry studies show that much of the dissolved sulfide and ferrous iron are present as FeS_(aq) cluster molecules: as a result, the free concentration of the West Camp water is poorly constrained. Concentrations of dissolved sulfide determined by colorimetry were lower than gravimetric assays obtained by AgNO₃ addition, implying that the FeS_(aq) clusters are not completely extracted by the Methylene Blue reagent. In contrast, the clusters are quantitatively extracted as Ag₂S after addition of AgNO₃. Isotopic analysis of co-existing aqueous sulfide and sulfate confirms that the sulfide was produced by sulfate-reducing bacteria (SRB). The H₂S-rich mine water is not confined to the immediate vicinity of the extraction well, but is also present in flooded mine shafts up to 3 km away, and in samples bailed from mine shafts at depths up to 300 m below static water level. This illustrates that SRB are well established throughout the southwestern portion of the extensive (>15 km³) Butte flooded mine complex.  相似文献   

Organic Matter Diagenesis in Acidic Mine Lakes     

C. Blodau  A. Peine  S. Hoffmann  S. Peiffer 《洁净——土壤、空气、水》2000,28(3):123-135

The significance of organic matter origin for carbon oxidation via sulfate and iron reduction in the sediments of three acid mine lakes is analyzed. Carbon reactivity was estimated by fitting first‐order expressions to measured rates. Carbon oxidation rates via sulfate and ferric iron reduction ranged from 3.4 to 4.7 mmol m^–2 d^–1 and resembled those reported for freshwater lakes. The estimated reaction constants increased from about 10^–3 a^–1 at the interface to the former mine grounds to 0.05 to 0.2 a^–1 at the current sediment‐water interface. Aquatic organic matter accounted for an estimated 45...75% of total carbon oxidation rates while it amounted only to about 5...14% of the total organic matter that had been deposited. The results of this study suggest that in highly acidic mine lakes the reactivity of the deposited organic matter can rapidly increase after flooding, enhancing carbon oxidation and internal neutralization rates in the sediments.  相似文献   

A synthesis of iron deposits in the eastern Tianshan,NW China     

《地学前缘(英文版)》2020,11(4):1271-1287

The northern Xinjiang region is one of the most significant iron metallogenic provinces in China.Iron deposits are found mainly within three regions:the Altay,western Tianshan,and eastern Tianshan orogenic belts.Previous studies have elaborated on the genesis of Fe deposits in the Altay orogenic belt and western Tianshan.However,the geological characteristics and mineralization history of iron deposits in the eastern Tianshan are still poorly understood.In this paper I describe the geological characteristics of iron deposits in the eastern Tianshan,and discuss their genetic types as well as metallogenic-tectonic settings,Iron deposits are preferentially distributed in central and southern parts of the eastern Tianshan.The known iron deposits in the eastern Tianshan show characteristics of magmatic Fe-Ti-V(e.g.,Weiya and Niumaoquan),sedimentary-metamorphic type(e.g.,Tianhu),and iron skarn(e.g.,Hongyuntan).In addition to the abovementioned iron deposits,many iron deposits in the eastern Tianshan are hosted in submarine volcanic rocks with well-developed skarn mineral assemblages.Their geological characteristics and magnetite compositions suggest that they may belong to distal skarns.SIMS zircon U-Pb analyses suggest that the Fe-Ti oxide ores from Niumaoquan and Weiya deposits were formed at 307.7±1.3 Ma and 242.7±1.9 Ma,respectively.Combined with available isotopic age data,the timing of Fe mineralization in the eastern Tianshan can be divided into four broad intervals:Early Ordovician-Early Silurian(476-438 Ma),Carboniferous(335-303 Ma),Early Permian(295-282 Ma),and Triassic(ca.243 Ma).Each of these episodes corresponds to a period of subduction,post-collision,and intraplate tectonics during the Paleozoic and Mesozoic time.  相似文献   

Colloid particle sizes in the Mississippi River and some of its tributaries,from Minneapolis to below New Orleans     

Colleen E. Rostad  Terry F. Rees  Stephen R. Daniel 《水文研究》1998,12(1):25-41

An on-board technique was developed that combined discharge-weighted pumping to a high-speed continuous-flow centrifuge for isolation of the particulate-sized material with ultrafiltration for isolation of colloid-sized material. In order to address whether these processes changed the particle sizes during isolation, samples of particles in suspension were collected at various steps in the isolation process to evaluate changes in particle size. Particle sizes were determined using laser light-scattering photon correlation spectroscopy and indicated no change in size during the colloid isolation process. Mississippi River colloid particle sizes from twelve sites from Minneapolis to below New Orleans were compared with sizes from four tributaries and three seasons, and from predominantly autochthonous sources upstream to more allochthonous sources downstream. © 1998 John Wiley & Sons, Ltd.  相似文献   

Numerical modeling of water yield of mine in Yangzhuang Iron Mine,Anhui Province of China          下载免费PDF全文

YANG Yun  WU Jian-feng  LIU De-peng 《地下水科学与工程》2015,3(4):352-362

This study develops a three-dimensional heterogeneous numerical model to simulate the water inrush process and predict the water yield for mineral exploration in Yangzhuang Iron Mine in Anhui Province. To identify the hydrogeological parameters of the aquifer in the study area, the model was calibrated and validated using the observed heads through the integrated trial-and-error and automated techniques. Also, the sensitivity analysis of the model was performed to evaluate the uncertainty associated with the calibrated model. According to the mine construction plan at different mining levels of -500 m, -600 m, and -700 m, the calibrated model was then applied to predict the water yields dependent on the different mining levels. As indicated by the prediction results, the numerical simulation model can systematically describe the groundwater system in the mining area and determine the source of water inrush in this iron mine. In conclusion, numerical analyses carried out in this study can provide guidance to decision-makers in balancing the iron ore mining and mine dewatering in the future.  相似文献   

宁芜盆地钟姑矿田典型铁矿成矿岩体Hf-O同位素特征及地质意义   总被引：2，自引：2，他引：0  

孙维安  袁峰  邓宇峰  刘光贤  杨迪  李现锁  傅斌 《岩石学报》2017,33(11):3559-3580

钟姑矿田位于宁芜盆地南部,受矿田内格状构造控制产出一系列早白垩世(129~132Ma)闪长岩及二长岩类侵入体,与铁矿床的形成密切相关,而区域内成矿岩体的研究尤其是岩浆岩的起源和演化有待进一步探讨。本次工作以矿田内的姑山辉石闪长玢岩、龙山辉石闪长岩、白象山闪长岩、钟九闪长岩和太平山二长岩等与铁成矿有关的岩体为研究对象,开展LA-ICP-MS原位锆石Hf同位素和SHRIMP原位O同位素研究。结果显示,钟姑矿田各成矿岩体具有较一致的锆石Hf-O同位素组成,~(176)Hf/~(177)Hf值为0.282425~0.282695,εHf(t)值为-12.3~-3.9,tDM2范围在1.26~1.86Ga;锆石δ18O集中于3.34‰~8.05‰,捕获锆石的176Hf/177Hf比值为0.282324~0.282487,εHf(t)=-15.8~-10.1,锆石tDM2年龄在1.72~20.8Ga之间,锆石δ~(18)O相对集中于5.90‰~6.51‰。钟姑矿田岩浆岩起源于富集的岩石圈地幔,同位素特征指示其携带板块俯冲和蚀变洋壳信息,钟姑矿田的成岩成矿作用应与伸展背景下古太平洋板块俯冲有关。与长江中下游其他矿集区岩浆岩对比研究表明,包括宁芜在内的长江中下游地区岩浆岩具有相同的地幔源区,以铁矿床为主的宁芜和庐枞盆地岩浆岩源区成分以交代岩石圈地幔为主,而以铜陵、繁昌为代表的铜多金属成矿区的岩浆岩受长江中下游新元古代基底的更多影响。  相似文献   

A Review of Study on Fe-C Interaction and Their Adsorption Properties to Soil Heavy Metal     

Zhao Zhuanjun  Yang Yanyan  Pang Yu  Zhao Lifang  Guan Yuli  Zhang Zhaohu 《地球科学进展》2017,32(8):867-874

Nowadays, the Fe-C coprecipitate mechanism is recognized by more and more scholars and becomes the hot topic in the environmental science. On the basis of discussing the interaction between iron oxide and organic matter, and the adsorption research progress of Fe-C complexes on heavy metals, the immobilization potential of Fe-C complexes on heavy metals in polluted soil were illustrated. The surface properties and physical characterizations of iron oxide are changed regularly with the interaction of organic matter, which lead to the higher adsorption capacity of Fe-C complexes in contrast to single iron oxide. Besides, the influences of pH values, organic matter types and surface properties of iron oxides on the adsorption capacity of Fe-C complexes on heavy metals were discussed. The excellent adsorption performance of Fe-C complexes in certain conditions will provide important theoretical basis for contaminated soil remediation.  相似文献