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Zircon isotopic ages from magnetite quartzites of the Jianping metamorphic complex, western Liaoning Province
Changqiu Wang,Wenyuan Cui,A. Kr ner,A. A. Nemchin
Chinese Science Bulletin , 2000, DOI: 10.1007/BF02887104
Abstract: Using the zircon Pb evaporation method and high precise ion microprobe analyses, zircon isotopic ages in supracrustal magnetite quartzites from Jianping metamorphic complex have been obtained. The results show that the deposition of the supracrustal rocks occurred around 2 552–2 520 Ma and the peak of granulite facies metamorphism reached at about 2 487 Ma; about (1 806±16) Ma, i.e. Mid-Proterozoic, the other possible metamorphic event with relatively low intensity happened in the study area. It is speculated that a likely tectonic setting where the Jianping metamorphic complex formed is an active continental margin that is involved in continental collision and crustal thickening shortly after its formation.
Zircon isotopic ages from magnetite quartzites of the Jianping metamorphic complex, western Liaoning Province
WANG Changqiu,CUI Wenyuan,A Kr ,ner,A A Nemchin,

科学通报(英文版) , 2000,
Abstract: Using the zircon Pb evaporation method and high precise ion microprobe analyses, zircon isotopic ages in supracrustal magnetite quartzites from Jianping metamorphic complex have been obtained. The results show that the deposition of the supracrustal rocks occurred around 2 552–2 520 Ma and the peak of granulite facies metamorphism reached at about 2 487 Ma; about (1 806±16) Ma, i.e. Mid-Proterozoic, the other possible metamorphic event with relatively low intensity happened in the study area. It is speculated that a likely tectonic setting where the Jianping metamorphic complex formed is an active continental margin that is involved in continental collision and crustal thickening shortly after its formation.
Ree geometries  [PDF]
Fabienne Haot,Koen Struyve,Hendrik Van Maldeghem
Mathematics , 2009,
Abstract: We introduce a rank 3 geometry for any Ree group over a not necessarily perfect field and show that its full collineation group is the automorphism group of the corresponding Ree group. A similar result holds for two rank 2 geometries obtained as a truncation of this rank 3 geometry. As an application, we show that a polarity in any Moufang generalized hexagon is unambiguously determined by its set of absolute points, or equivalently, its set of absolute lines.
Provenance and Source Area Weathering Derived from the Geochemistry of Pre-Cenomanian Sandstones, East Sinai, Egypt  [PDF]
Adel I. M. Akarish,Amr M. El-Gohary
Journal of Applied Sciences , 2011,
Abstract: The study aimed at characterizing the geochemical compositions of the pre-Cenomanian sandstones of Gebel Ghazalani area, east Sinai. X-Ray Fluorescence (XRF), Induced Coupled Plasma-Mass Spectrometry (ICP-MS) and Induced Coupled Plasma-Emission Spectrometry (ICP-ES) analyses were used to determine the sandstone composition. Major, trace and rare earth element compositions of the sandstones have been investigated to determine their provenance, tectonic setting and the influence of weathering conditions. The studied succession (~214 m thick) starts by undifferentiated pre- Carboniferous sediments that unconformably overlies the Katherina Volcanics and followed upwards by the Lower Cretaceous sandstones of the Malha Formation. The pre-Cenomanian sandstones are enriched in SiO2 and High Field Strength Elements (HFSE) and are depleted in mobile elements, Large-Ion Lithophile Elements (LILE), transition metals and possess low contents of TiO2 and Fe2O3. Their Rare Earth Elements (REE) pattern displays high Light REE/Heavy REE (LREE/ HREE) ratio, flat HREE and a significant negative Eu anomaly. The source area may have contained quartzose sedimentary rocks. The geochemical data support deposition in a passive continental margin and the sediments were derived from felsic (granitic) source rocks. Trace and REE data as well as the high values of the weathering indices: Chemical Index of Alteration (CIA), Plagioclase Index of Alteration (PIA) and Chemical Index of Weathering (CIW) suggest moderate to extreme weathering conditions in the source area or during transportation. Also, they indicate that recycling processes might have been significant. Clay content, zircons and quartz dilution are responsible for the variation in REE contents.
Stochastic reconstruction of sandstones  [PDF]
C. Manwart,S. Torquato,R. Hilfer
Physics , 2000, DOI: 10.1103/PhysRevE.62.893
Abstract: A simulated annealing algorithm is employed to generate a stochastic model for a Berea and a Fontainebleau sandstone with prescribed two-point probability function, lineal path function, and ``pore size'' distribution function, respectively. We find that the temperature decrease of the annealing has to be rather quick to yield isotropic and percolating configurations. A comparison of simple morphological quantities indicates good agreement between the reconstructions and the original sandstones. Also, the mean survival time of a random walker in the pore space is reproduced with good accuracy. However, a more detailed investigation by means of local porosity theory shows that there may be significant differences of the geometrical connectivity between the reconstructed and the experimental samples.
The norm of a Ree group  [PDF]
Tom De Medts,Richard M. Weiss
Mathematics , 2009,
Abstract: We give an explicit construction of the Ree groups of type $G_2$ as groups acting on mixed Moufang hexagons together with detailed proofs of the basic properties of these groups contained in the two fundamental papers of Tits on this subject. We also give a short proof that the norm of a Ree group is anisotropic.
Geochemistry of Tikak Parbat Sandstones and Tipam Sandstones Occurring in and around Dilli Area, Sivasagar District, Assam, India  [PDF]
Hrishikesh Baruah, Asim Dutta Lahkar, Balen Bhagabati, Ranjeeta Kar, Pradip Kumar Das
Open Journal of Geology (OJG) , 2017, DOI: 10.4236/ojg.2017.78083
Abstract: This study presents a geochemical investigation of Tikak Parbat and Tipam Sandstone Formations occurring in and around Dilli area, Sivasagar, Assam. Petrographically Tikak Parbat and Tipam sandstones are mainly quartzose arenite to sublitharenite types with their constituents being derived from recycled orogen provenance under sub-humid to humid climatic conditions. Geochemically, sandstones of both the formations range from sublitharenite to wacke. They indicate a recycled orogen source and influence of humid to arid condition. Source rocks of Tikak Parbat sandstones were more weathered than the Tipam sandstones. While Tikak Parbat sandstones show affinity towards passive margin, Tipam sandstones hint at active continental margin setup, where clasts were supplied from uplifted areas. Upliftment of provenance covering areas of Naga Patkai Range in the south east and Eastern Himalayas along the syntaxial bend during mid Miocene affected the sandstones. Tikak Parbat sandstones reflect a stable tectonic setup which later underwent a phase of volatility leading to deposition of the Tipam sandstones. Our study supports a sediment supply from the upper continental crust, largely of granitic composition, however, with a significant variation in their depth of source supply. Trace element analyses indicate depositional setup with low ventilation marked by both oxic and anoxic phases.
The evolution of the atmosphere in the Archaean and early Proterozoic
Euan Nisbet,C. Mary R. Fowler
Chinese Science Bulletin , 2011, DOI: 10.1007/s11434-010-4199-8
Abstract: Key steps in atmospheric evolution occurred in the Archaean. The Hadean atmosphere was created by the inorganic processes of volatile accretion from space and degassing from the interior, and then modified by chemical and photochemical processes. The air was probably initially anoxic, though there may have been a supply of oxidation power as a consequence of hydrodynamic escape to space of hydrogen from water. Early subduction may have removed CO2 and the Hadean planet may have been icy. In the Archaean, as anoxygenic and then oxygenic photosynthesis evolved, biological activity remade the atmosphere. Sedimentological evidence implies there were liquid oceans despite the faint young Sun. These oceans may have been sustained by the greenhouse warming effect of biologically-made methane. Oxygenesis in the late Archaean would have released free O2 into the water. This would have created oxic surface waters, challenging the methane greenhouse. After the Great Oxidation Event around 2.3 to 2.4 billion years ago, the atmosphere itself became oxic, perhaps triggering a glacial crisis by cutting methane-caused greenhouse warming. By the early Proterozoic, all the key biochemical processes that maintain the modern atmosphere were probably present in the microbial community.
Geochemistry of Mesozoic detrital rocks and its constraints on provenance in Feixi area, Anhui provence
安徽肥西中生代碎屑岩地球化学特征及其对物源制约

LI ShuangYing,LI RenWei,YUE ShuCang,WANG DaoXuan,LIU Yin,MENG QingRen,JING FuQuan,
李双应
,李任伟,岳书仓,王道轩,刘因,孟庆任,金福全

岩石学报 , 2004,
Abstract: The Mesozoic strata developing in the south of Hefei basin, Feixi area of Anhui Province, comprising Fanghushan, Yuantongshan and zhougongshan Formations, are primarily composed of sandstones. Though their source rocks may be chienfly from the Dabie Orogenic Belt on basis of previous studies, there is important implication that exactly limit the types of the source rocks, thus constructing corresponding relations between sedimentary sequences and various tectonic units, and find out the extent of actual influence of the provenances of Dabie Orogenic Belt and Huabei Landmas. Based on petrochemical analysis of the sandstones, they consist mainly of greywacke, lithic arenite and arkose, and major element concentrations of the sandstones fall in with Late Proterozoic orogenic sandstones. The unanimous REE diagrams of the sandstones suggest that they were formed from the same source rocks and tectonic setting. The data of REE and trace elements indicate that the source rocks were mainly composed of Fuziling and Luzhengguan Groups, limited for Dabie complex and no Huabei Landmass matter. Meanwhile, Dabie orogenic belt might have not provided material for the Mesozoic deposition of the south of Huabei Landmass. Th-Co-Zr/10 and Th-Sc-Zr/10 diagrams and trace element ratios suggest that the provenance attributes to continental island-arc, which examines the former conclusion and brings to light the tectonic setting inherit of petrochemistry for detrital rocks formed in peripheral basins.
New Possibility for REE Determination in Oil  [PDF]
Alexander Soin,Tatiana Maryutina,Natalya Musina,Andrey Soin
International Journal of Spectroscopy , 2012, DOI: 10.1155/2012/174697
Abstract: A novel approach of rare earth elements (REE) determination in crude oil is suggested. Special application of countercurrent chromatography (CCC) is used as a sample pretreatment tool. An oil sample is continuously pumped through the rotating coil column (RCC) as a mobile phase, while an aqueous phase (nitric acid solution) is retained as a stationary phase. Two phases are kept well mixed and agitated, but there is no emulsion at the interface under the chosen conditions. Special features of CCC give an opportunity to vary the volume of oil samples to be analyzed from 10?mL to 1?L or more. Trace metals are preconcentrated into 10?mL of stationary phase (acidic solutions) pumped out of the column so that analysis can be easily determined with inductively coupled plasma mass spectrometry (ICP-MS) without additional sample preparation procedures. Optimal concentration of nitric acid in the stationary phase for preconcentration of REE from oil by CCC has been investigated. The combination of CCC with ICP-MS gives the possibility to develop a rapid, reliable, and accurate method of trace metal including rare earth elements (REE) determination in crude oils and oil products. Such method could be an alternative for unexpanded and expensive neutron-activation analysis (NAA). 1. Introduction Microelemental and REE contents of oil are very important for estimating oil’s age and for developing theories of oil’s origin. It is known that information about hydrocarbons genesis could be obtained using element ratios. Such ratios also could be determinative as the georeconnaissance data. From this point of view, REE content/ratios are of the prime interest. REE ratios could be used as the reference points for different oils (from different deposits/fields) like for most geological samples as rocks, minerals, and ores [1, 2]. In the meantime, REE analysis of oils is still a very complicated analytical task. There are no methods of preconcentration of metals from oil to aqueous phases, and REE contents are usually at ppt level and lower. Also there are no standard methods (ASTM D, IP, EN, or UOP) or standard/reference samples for REE analysis of oils. It should be mentioned that articles and studies dedicated to REE content in oils could be found really seldom. Thus, ICP-MS determination of REE in oils was published [3] when acid digestion was used for sample preparation. As a result, most of REE, measured (including Pr, Sm, Eu, Gd, Dy, Er and Yb) were “not detected.” Suggesting hybrid method (CCC and ICP-MS) enables lessening detection limit (DL) and detecting most of
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