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Hydrodynamic regime as a major control on localization of uranium mineralization in sedimentary basins

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Science China Earth Sciences 2014年第12期57卷 2928-2933页

作者： CHI GuoXiang XUE ChunJi department of geology University of Regina State Key Laboratory of geological Processes and Mineral Resources China University of Geosciences

Uranium deposits in sedimentary basins can be formed at various depths,from near surface to the *** many factors may have played a role in controlling the location of mineralization,examination of various examples in the world,coupled with numerical modeling of fluid flow,indicates that the hydrodynamic regime of a basin may have exerted a major control on the localization of uranium *** a basin is strongly overpressured,due to rapid sedimentation,abundance of low-permeability sediments or generation of hydrocarbons,fluid flow is dominantly upward and uranium mineralization is likely limited at shallow *** a basin is moderately overpressured,upward moving fluids carrying reducing agents may meet downward moving,oxidizing,uranium-bearing fluids in the middle of the basin,forming uranium deposits at moderate *** a basin is weakly or not overpressured,either due to slow sedimentation or dominance of high-permeability lithologies,minor topographic disturbance or density variation may drive oxidizing fluids to the bottom of the basin,leaching uranium either from the basin or the basement,forming unconformity-type uranium *** is therefore important to analyze the hydrodynamic regime of a basin in order to predict the most likely type and location of uranium deposits in the basin.

关键词： uranium deposits localization sedimentary basins hydrodynamic regime fluid overpressure

Regional landslide forecasting model using interferometric SAR images

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Journal of Central South University 2008年第S2期15卷 168-173页

作者：董育烦张发明高正夏蒯志要 department of Earth Science and engineering Hohai University department of geological engineering Chang’an University

Method of obtaining landslide evaluating information by using Interferometric Synthetic Aperture Radar (InSAR) technique was discussed. More precision landslide surface deformation data extracted from InSAR image need take suitable SAR interferometric data selecting, path tracking, phase unwrapping processes. Then, the DEM model of scope and surface shape of the landslide was built. Combining with geological property of landslide and sliding displacements obtained from InSAR/D-InSAR images, a new landslide forecasting model called equal central angle slice method for those not obviously deformed landslides was put forward. This model breaks the limits of traditional research methods of geology. In this model, the landslide safety factor was calculated by equal central angle slice method, then considering the persistence ratio of the sliding surface based on plastic theory, the minimum safety factor was the phase when plastic area were complete persistence. This new model makes the application of InSAR/D-InSAR technology become more practical in geology hazard research.

关键词： InSAR landslide forecasting equal central angle slice method monitoring and evaluation model

Anisian(Middle Triassic)Conodonts of the Kocaeli Triassic,Western Turkey

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Journal of Earth Science 2021年第3期32卷 616-632页

作者： Ali Murat Kilic department of geological engineering Faculty of EngineeringBalikesir UniversityBalikesirTurkey

The present study of Anisian(Middle Triassic)conodonts from the Kocaeli Peninsula(western Turkey)encompasses over 10 species of the families Gondolellidae and Gladigondolellidae,providing Early and Middle Triassic time constraints,Chiosella timorensis(Nogami,1968);Cornudina oezdemirae Gedik,1975;Gladigondolella tethydis(Huckriede,1958);Neostrachanognathus tahoensis Koike,1998;Paragondolella aegaea(Bender,1970);Paragondolella bulgarica Budurov and Stefanov,1975;Nicoraella kockeli(Tatge,1956);***(Sudar and Budurov,1979),and Gladigondolella *** established are Paragondolella hirschii *** and Budurov;*** *** ,Budurov,Petrunova and Mirauta;and *** ***.K?l??.The Kocaeli Anisian conodonts show a faunal affinity with *** present Anisian fauna is characteristic of the *** strong homeomorphy that characterizes the Anisian in western North America is discussed.

关键词： Triassic Anisian Aegean Bithynian conodonta Gebze(Kocaeli)

Biostratigraphy and palaeoenvironment of deposition of Nsukka Formation,Anambra Basin,southeastern Nigeria

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Journal of Palaeogeography 2017年第1期6卷 45-59页

作者： S.A.Bankole A.O.Ola-Buraimo department of Chemical and geological Sciences Al-Hikmah UniversityllorinNigeria department of geology Federal UniversityBimin KebbiNigeria

Biostratigraphy investigation of Nsukka Formation was carried out by subjecting weLt cutting samples obtained from Nzam-1 weLL to patynotogicat studies with the view towards determining the relative geologic age and pataeoenvironment of deposition of the sediments. SampLes were treated in the Laboratory through digestion with hydrofluoric acid, sieving with 5 μm, oxidation with Nitric acid and mounting of the sLides into sections with DPX mountant. A fairLy high abundance and diversity of miospores were recovered, white the interval （847-1372 m） contains distinctive and diagnostic patynomorphs which are stratigraphicatty important. A Spinizonocolpites baculatus assemblage zone was established based on the basal occurrence of S. baculatus, Spinizonocolpites echinatus, Constructipollenites ineffectus, Periretisyncolpites sp. Periretisyncolpites giganteus, Monocolpites sp 1, Foveotriletes margaritae, Syncolporites marginatus, and Longapertites marginatus. The upper part of the intervat is marked by association of Anacolosidites luidonisis （at top）, Mauritiidites crassibaculatus, Retistephanocolpites williamsi, Proteacidites dehaani, Echitriporites trianguliformis, Proxapertites cursus, Retidiporites magdalenensis, S. baculatus, Retitricolpites gigeonetti, F. margaritae and Araucariadtes sp. The Nsukka Formation is dated as Late Maastrichtian based on the cooccurrence of recovered index fossits. Importantly, Cretaceous-Tertiary （K/T） boundary is marked by high fossil content in the Maastrichtian sediments compared to paucity in patynomorph that characterises the overtying Pateocene facies. Pataeoenvironment of the anatyzed section varies atternatety from marginaL marine to continental setting based on the presence of land-derived miospores and dinoflagettates.

关键词： Biostratigraphy Palaeoenvironment Assemblage Gonyaulacacean/Peridinacean ratio Index fossil Anambra Basin

Lakshanhatti stromatolite, India： Biogenic or abiogenic？

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Journal of Palaeogeography 2016年第3期5卷 292-310页

作者： Adrita Choudhuri Subir Sarkar Wladyslaw Altermann Soumik Mukhopadhyay Pradip K.Bose department of geological Sciences Jadavpur University Kolkata 700032 India department of geology University of Pretoria Pretoria 0002 South Africa

Abstract The extraordinary lateral continuity of isopachous stromatotite laminae in the -87 m-thick Mesoproterozoic Lakshanhatti Dolomite （India） evinces chemical precipitation. Fan-shaped crystals grown on tamina surfaces further corroborate this contention; growth of fan-shaped crystats under the overhanging stromatolite column-margin indicates direct carbonate precipitation from ambient waters. The fan-shaped crystats are stacked up, separated onty by thin dark micritic taminae. In a retativety upper stratigraphic in- terval of the formation, tighter laminae characterized by a dotted texture and traversed by numerous winding tubutar voids change graduatty upwards into dark micritic taminae. Some sporadicatty distributed lenticutar intraciastic beds also have the similarly dark micritic coatings. Ctear carbonate cement crusts atso occur between laminae and between successive dark micritic coats around intraciasts. DuU cathodotuminescence （CL） characterizes this cement as weU as the cement lining within earty dia^enetic voids, in contrast, the taminae with dotted textures show dirty orange luminescence, white the dark micritic taminae and the dark micritic grain-coats display dear bright orange luminescence. Pyrite and its pseudomorphs are preferabty concentrated along the dark micritic laminae. Carbon content in these dark micritic components, whether laminae or coats, is much higher than in the lighter components, exceeding what can be accounted for their CaMg（COs）2 composition. A large part of this carbon is kerogen, ptausibly biogenic. The dark components are, therefore, reasonably, though not unequivocally, assumed to be microbial mats. Degradation of the mats might have given rise to the tight laminae with dotted textures. The fuzzy-margin tubes within the tight laminae probabty manifest the escape of gases generated during organic matter decomposition. Si-At-rich terrigenous fines thinty draping the dark carbonaceous taminae was possibty the resutt of baft

关键词： StromatoHte Lamina continuity Mesoproterozoic Lakshanhatti Dolomite Member Inorganicprecipitation Kerogen enrichment Filamentous microbiota

Structure transition of nano-titania during calcination

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Journal of Central South University of Technology 2003年第4期10卷 275-279页

作者：李国华王大伟徐铸德陈卫祥 department of Chemistry School of geology and Environment engineering

In order to study the structure transition during calcination, nano-titania powders prepared by hydrolyzing precipitation approach and calcined at 300, 400, 500, 600 and 700 ℃ were characterized by XRD, TEM and electron diffraction(ED), respectively. The results show that titania powders calcined below 500 ℃ are almost composed of anatase, rutile appears below 500 ℃ and its ratio increases gradually with increase of calcin temperature; nano-titania particles are smaller than 40 nm mostly and the dispersion is related to calcining temperature; the inter-planar distances of nano-anatase single crystalline change gradually when calcing temperature increases to 500 ℃; so do that of nano-rutile single crystalline when calcining temperature charges from 600 to 700 ℃. The conclusions can be drawn that the temperature of transformation from anatase to rutile is below 500 ℃ and the process carries on gradually. Both inter-planar distances and the structure of nano-titania transform gradually with increasing calcing temperature.

关键词： nano-titania phase transformation structure transition inter-planar distances

In-Situ SHRIMP U-Pb Dating of Xenotime Outgrowth on Detrital Zircon Grains from the Changzhougou Formation of the Ming Tomb District, Beijing

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Acta Geologica Sinica(English Edition) 2015年第1期89卷 304-305页

作者： SHI Yuruo Kennedy ALLEN Aleinikoff JOHN SONG Tianrui LI Linlin SUN Huiyi Beijing SHRIMP Center Institute of Geology Chinese Academy of Geological Sciences department of Applied Physics Curtin University U.S. geological Survey

SHRIMP U-Pb dating of diagenetic xenotime from sedimentary rocks has provided age constraints for sedimentary diagenesis （McNaughton et al., 1999; Fletcher et al., 2000; England et al., 2001; Rasmussen et al., 2004; Vallini et al., 2007）. Xenotime （YPO4） may grow during early diagenesis, typically being present as a trace constituent in siliciclastic sedimentary rocks （Rasmussen, 2005）, in the form of syntaxial outgrowths on detrital zircon grains. Diagenetic xenotime occurs in a wide variety of rock types, including conglomerate,

关键词： SHRIMP Pb Beijing

geology and Mineral Chemistry of Gold Mineralization in Mirge-Naqshineh Occurrence(Saqez,NW Iran):Implications for Transportation and Precipitation of Gold

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Acta Geologica Sinica(English Edition) 2018年第1期92卷 210-224页

作者： Golale ASGHARI Samad ALIPOUR Hossein AZIZI Hassan MIRNEJAD department of geology Urmia University Mining department Faculty of Engineering University of Kurdistan department of geology Faculty of Science University of Tehran

The Mirge-Naqshineh gold district is situated at northwest of Iran with a NW-trending brittle- ductile shear zone. It is hosted by Precambrian meta-sedimentary and meta-volcanic units traversed by mineralized quartz veins. In terms of cross-cutting relationships and sulfide content three types of quartz veins are identified in the region. Among those, parallel to bedding quartz vein （type I） is the main host for gold mineralization. Gold is found in three different forms： 1） submicrometer-size inclusions of gold in arsenian pyrite, 2） as electrum and 3） in the crystal lattice of sulfides （pyrite, galena and chalcopyrite）. Six types of pyrite （Pyl-Py6） were identified in this ore reserve. Py3 coexists with arsenopyrite and contains the greatest As-Au concentrations. There is a negative correlation between the As and S contents in Py2 and Py3, implying the substitution of sulfur by arsenic. Pyrites and mineralized quartz veins were formed via metamorphic-hydrothermal fluid and reflect the gold-transportation as Au（HS）2 under reducing and acidic conditions. The gold precipitation mainly controlled by crystallization of arsenian pyrite during fluid/rock interactions and variation offO2. The volcanic host rock has played an important role in gold concentration, as Py3 in this rock contains inclusion of gold particles, but gold is within the lattice of pyrite in phyllite or other units.

关键词： gold quartz veins mineral chemistry EPMA Mirge-Naqshineh Iran

Evaluation of relative tectonic activity along the Priene-Sazli Fault(Soke Basin,southwest Anatolia):Insights from geomorphic indices and drainage analysis

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Journal of Mountain Science 2019年第4期16卷 909-923页

作者： Savas TOPAL Pamukkale University Department of Geological EngineeringKinikli Campus

The West Anatolia Extensional Zone, which has a width of about 300 km, is located within the Alpine-Himalayan belt and is one of the regions with intense seismic activity in the world. The most important geomorphological structures in this area are three main graben structures resulting from regional N-S extension since the Early Miocene. These structures are the E-W trending Büyük Menderes, Kü?ük Menderes, and Gediz grabens. S?ke Basin is located at the SW end of the Büyük Menderes graben. The lineaments which control the NW of S?ke Basin have a length of approximately 40 km and have been defined as the Priene-Sazl? Fault(PSF). The PSF is seismically active, and the last large earthquake(the S?ke-Balat earthquake; Ms: 6.8) was produced on July 16 th of 1955. The ancient city of Priene, which was located in the study area, suffered from destructive earthquakes(in the 4 th century and 2 nd century BC, in the 2 nd century AD, during the Byzantine period and after the 12 th century BC). This study aims to reveal the effect of the PSF on the morphotectonic evolution of the region and the relative tectonic activity of the fault. To this end, it was the first time the stream length gradient index(SL: 130-1303), mountain-front sinuosity(Smf: 1.15-1.96), valley floor height and valley width ratio(Vf: 0.27-1.66), drainage basin asymmetry(AF: 0.15-0.76), hypsometric curve(HC) and hypsometric integral(HI: 0.22-0.86) and basin shape index(Bs: 1.04-5.75) along the mountain front that is formed by the PSF. Using a combination of the mountain-front sinuosity(Smf), valley floor height and valley width ratio(Vf), it is found that the uplift ratio in the region is not less than 0.05 mm/yr and the relative tectonic activity of PSF is high. According to the relative tectonic activity index(Iat) obtained from geomorphic indices, the southwest part of the PSF is relatively more active than the northeast part. As a result, I posit that the PSF has the potential to produce earthquakes in t

关键词： Geomorphic indices Tectonic activity Earthquake Priene-Sazli Fault Soke basin Western Anatolia