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A radical reinterpretation of the growth and form of the stromatolite Conophyton lituus(Maslov)from evidence of syngenetic biofilm mineralisation

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Journal of Palaeogeography 2022年第1期11卷 69-84页

作者： Robert V.Burne Research School of Earth Sciences The Australian National University CanberraACT 0200Australia School of Earth and Environmental Sciences The University of QueenslandBrisbaneQLD 4072Australia

Conophyton(Maslov)is a cylindroidal stromatolite form-genus characterized by nested conical laminae.Well-preserved Conophyton,up to 4 m tall and with basal diameters of up to 50 cm,are exposed in the Proterozoic Atar Formation of Mauritania,where many occur together,in growth position,as fields of individual columns spaced between 5 and 70 cm apart.The uniformity of these forms and their regular distribution suggest that they grew in quiet-water environments below wave base.Evidence for their penecontemporaneous organomineralization is indicated by nearby toppled examples of undeformed Conophyton forms alongside eroded lithified Conophyton fragments in carbonate breccias.Two characteristics of Conophyton have been used to classify the structures-the form of the lamination and the nature of its axial structure.A mathematical/physical model provides an explanation for the growth pattern of Conophyton.It predicts that coniform structures with thickened axial zones form when upward organic growth of a biofilm moderately exceeds the rate of its mineralization.The varying characteristics of these features between different forms of Conophyton are thought to reflect biomineralization of the decaying biofilm rather than differences in the composition of microbial communities.A modern example of a syngenetic mineralization process capable of producing similar structures has been observed in the contemporary sediments of Lake Preston,Western Australia,where benthic microbial mats are being transformed into coniform lithified crusts.The initial biomineralization of the coniform mat forms magnesium silicate that first coats and permineralizes web-like microbial extracellular polymeric substances(EPS)and then coalesces into a uniform mass that provides mechanical strength to the cones.At a later stage,massive carbonate crystal growth occurs that over-prints much of this texture,leaving only small,remnant areas of the magnesium silicate phase.Many fossil Conophyton are composed of dolomite,and the remains of the microbial comm

关键词： Conophyton Morphogenesis Proterozoic Stromatolite Microbialite mineralisation Biofilm Lake Clifton Lake Preston Maslov

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Late Jurassic Intracontinental Extension and Related mineralisation in Southwestern Fujian Province of SE China:Insights from Deformation and Syn-Tectonic Granites

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Journal of Earth Science 2021年第1期32卷 158-173页

作者： Rui Cao Xinghua Ma Leon Bagas Yongbao Gao Demin Liu Zailai Mou Kay Laboratory of Earth Exploration and Information Techniques Ministry of educationChengdu University of TechnologyChengdu 610059China State Key Laboratory of Geological Processes and Mineral Resources China University of GeosciencesBeijing 100083China Xi'an Center of China Geological Survey Xi'an 710054China Centre for Exploration Targeting the University of Western AustraliaCrawley WA 6009Australia MNR Key Laboratory of Metallogeny and Mineral Assessment Institute of Mineral ResourcesChinese Academy of Geological SciencesBeijing 100037China School of Earth Sciences China University of GeosciencesWuhan 430074China

Late Mesozoic igneous intrusions and extensional structures in Carboniferous to Permian sequences in the SW Fujian region acted as important controls on the localisation of Fe-polymetallic de-posits.Here we document the identification of extensional deformation at shallow crustal levels and syn-tectonic granites related to normal faults.Based on spatial distribution and structural features,the extensional deformation can be divided into cover-only and basement-intersecting styles.A series of syn-tectonic plutons were emplaced into the footwall of normal faults.Representative samples of the Tangquan Granite have high SiO2(66.4 wt.%-73.9 wt.%)assays and Mg#values(37-59).The samples also have relatively homogenous initial 87Sr/86Sr(0.7083-0.7089)andεNd(-9.2--10.2)values.Geochemical and isotopic evidences indicate that the Tangquan granite originates from a hybrid source including lower crustal-derived felsic and lithospheric mantle-derived mafic magmas.Zircon U-Pb dating indicates that the granodiorite phase from the pluton crystallised at 161±4 Ma and the monzogranite phase crystallised at 159±1 Ma.Combined with the granitic rocks in a wider region of SE China,the widespread granitic magmatism and polymetallic mineralisation have been synchronous during the Late Mesozoic,probably resulting from extensional tectonics related to the lithospheric thinning.

关键词： extensional tectonic intracontinental deformation granitic magmatism mineralisation SE China

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The mineralisation Process as Deduced from Sr Isotopic Data from Lonplats' Eastern Platinum Mine,Western Bushveld Complex and Large-Scale Geometry of the Floor to the Merensky Reef

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地学前缘 2009年第S1期16卷 164-165页

作者： Refilwe Shelembe R.Grant Cawthorn Council for Geoscience University of the Witwatersrand

At Eastern Platinum Mine in the western Bushveld Complex,the entire Merensky Pyroxenite Unit reaches up to 11 m in thickness,in contrast to many sections where it is only 1-3 m thick.This greatly expanded section allows for a more detailed investigation of processes that are normally telescoped to the point of being irresolvable.Very minor platinum-group element(PGE)

关键词： PGE mineralisation pressure increase funnel-shaped magma chamber

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ARTICLE Petrographic and mineralisation Potentials of Precambrian Pegmatities and Associated Rock Units of Olode Area,Southwestern Nigeria

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Journal of Geological Research 2020年第4期2卷 62-74页

作者： S.I.Okonkwo S.O.Idakwo federal university of technology owerrip.m.2.1526owerriimo statenigeria ibrahim badamasi babangida university lapaip.m.2.11lapainiger statenigeria

The geology of the Olode area, south-western Nigeria was investigatedpetrographically and geochemically in order to elucidate the mineralisationpotential of the rock units in the area. The area under study is generallychange to underlained by granite gneiss, mica schist and pegmatites.Petrographical studies indicated prevalence of anhedral quartz (30 - 50%),plagioclase (14 - 20%), orthoclase (12 - 15%), muscovite (11 - 15%),tourmaline (6 - 10) and other minerals (8 - 11%) for the pegmatite. Thehigh value of SiO2 and Al2O3 is consistent with the petrographical study.High values and wide range in Ba (34 - 737 ppm) and Zr (3.8 - 132.6 ppm)strongly support a mixture of igneous and sedimentary. The bivariant plotsof Rb vs K/Rb, Zn vs K/Rb and Th vs K/Rb indicated a partial series offractionation, suggesting that the pegmatites are of rare element classeswhile granite gneiss and mica schist belong to the barren muscovite andrare element classes. This was supported by high ratios of K/Cs and K/Babut low Th/U values indicating distinctively low rare metal mineralization.The plot of Na2O/Al2O3 vs K2O/Al2O3 revealed an igneous precursor for allthe rock units. The negative Eu anomalies especially in the pegmatitic rockunit indicates fractionation and point toward a late metasomatic effect andtheir relatively weak negative Ce anomalies, also suggest their rare metalmineralization. The pegmatites, granite gneiss and mica schist of Olodearea considered as barren as all the samples plotted below the Gordiyenkosand Beus’ line of mineralization.

关键词： Pegmatite and associated rocks Geochemistry mineralisation Gordiyenkos and Beus’line Olode

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Estimating Potential Nitrogen mineralisation Using the Solvita Soil Respiration System

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Open Journal of Soil Science 2015年第12期5卷 319-323页

作者： Richard L. Haney Elizabeth B. Haney Grassland Soil and Water Research Laboratory Agricultural Research Service United States Department of Agriculture (USDA-ARS) Temple TX USA Texas AgriLife Research & Extension Center Texas A & M University Temple TX USA

Nitrogen (N) mineralisation contributes considerably to crop growth in fertilized and unfertilized fields. It is useful to be able to assess potential N mineralisation to increase fertilizer application efficiency, prevent excessive N runoff, and improve environmental system models. The microbes present in soil mineralize N based on many factors, including soil temperature and moisture, tillage, and levels of organic C and N. The measurement of soil’s ability to mineralize N is considered a good indicator of soil quality. Many methods have been developed to estimate N mineralisation in the laboratory and field. The 7-day anaerobic N mineralisation method developed in the 1960’s is considered reliable and is often used to compare new N-mineralisation testing methods. This study examines the use of soil CO2 evolution as determined using the Solvita Soil Respiration System (Solvita) for estimating N mineralisation by comparing it directly to the anaerobic N mineralisation test. Measured CO2 using Solvita was strongly correlated with anaerobic N mineralisation (r2 = 0.82). Results indicate that the Solvita Soil Respiration System can be used to rapidly assess soil respiration and relative N mineralisation potential in any given soil and is considerably faster and easier to perform in a laboratory setting than the anaerobic N mineralisation test.

关键词： Anaerobic N Nitrogen mineralisation Soil Respiration

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Ionic conductivity anomaly in soil cover——Exploration of blind mineralization beneath regolith cover

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Science China Earth Sciences 2010年第5期53卷 649-656页

作者： KEELING John L. Primary Industries and Resources South Australia (PIRSA)

This paper briefly describes the formation of ionic conductivity anomalies in soil cover, and the characteristics of ionic composition that forms conductivity anomalies, based on the theory of geoelectrochemical halo. Based on some practical results of soluble ions in soil cover and soil conductivity derived from a number of mining areas of both China and overseas, here we present the correlation of a conductivity anomaly with the ionic composition and establish a model for the formation of conductivity anomalies in soil cover. The results indicate that the formation of a conductivity anomaly is not a simple transformation of a secondary geochemical anomaly. A conductivity anomaly is formed as the result of electrochemical and chemical processes, by transformation of orebody into various ionic haloes through four physicochemical processes: 1) dissolution of the orebody, 2) migration of dissolved matter, 3) conversion of matter near the surface, and 4) the formation of ionic conductivity anomalies. The conductivity anomaly, as a physical parameter, essentially represents the integration of various geochemical compositions and is controlled by a set of particular ionic groups.

关键词： ionic conductivity regolith mineralisation exploration

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A Review of Fluid Inclusions in Diagenetic Systems

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Acta Geologica Sinica(English Edition) 2015年第3期89卷 697-714页

作者： Terrence P.MERNAGH Research School of Earth Sciences The Australian National University

The study of fluid inclusions can help constrain the conditions at which diagenetic minerals precipitated,leading to a better understanding of the geologic controls and relative timing of changes in porosity and/or mineralising events.Many of the diagenetic minerals are easily deformed and it is important to check for any post-entrapment changes to the inclusions.Possible post-entrapment changes include reaction with the host crystal,necking down,nucleation metastability and thermal reequilibration.The recommended method of detecting these problems is to examine individual fluid inclusion assemblages（FIAs） and report data for each individual FIA.These studies have been enhanced by the development of new micro-analytical techniques such as micro-fluorescence spectroscopy,micro-infrared spectroscopy,nuclear magnetic resonance,various mass spectrometry techniques and the analysis of individual fluid inclusions using laser ablation/decrepitation methods.Special techniques have been developed for hydrocarbon-bearing inclusions such as the Grains containing Oil Inclusions（GOI）,Fluid Inclusion Stratigraphy（FIS）,and the Molecular Composition of Inclusions（MCI） techniques.The fluid inclusions that form in some minerals during diagenesis provide the only direct means of examining the fluids present in these systems.They provide useful temperature,pressure,and fluid composition data that cannot be obtained by other means.

关键词： Fluid inclusions diagenesis saline formations hydrocarbons mineralisation

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A stepwise process for carbon dioxide sequestration using magnesium silicates

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Frontiers of Chemical Science and Engineering 2010年第2期4卷 133-141页

作者： Johan FAGERLUND Experience NDUAGU Inês ROMÃO Ron ZEVENHOVEN Åbo Akademi University Thermal and Flow EngineeringBiskopsgatan 8FI-20500Åbo/TurkuFinland visiting from University of Coimbra Department of Chemical EngineeringPólo IIPinhal de Marrocos3030-290 CoimbraPortugal

This work involves the production of magnesium in the form of Mg(OH)_(2)from serpentinite rock(nickel mine tailing)material followed by conversion into MgCO_(3)using a pressurised fluidised bed(PFB)reactor operating at 400℃-600℃and pressures up to 2.85 MPa.Our approach is rooted in the thermodynamic fact that the reaction between Mg(OH)_(2)and gaseous CO_(2)forming MgCO_(3)and water releases significant amounts of heat.The main problem is,however,the chemical kinetics;the reaction is slow and has to be accelerated in order to be used in an economically viable process for large-scale(~1 Mt/a)CO_(2)sequestration.We have constructed a labscale PFB reactor test-setup for optimising the carbonation reaction.At high enough temperatures and conversion levels the reaction should provide the heat for the proceeding Mg(OH)_(2)production step,making the overall process energy neutral.So far we have been able to achieve a conversion degree of 26%at 500℃and 2.85 MPa after 30 min(particle size 125-212μm).In this paper the test facility and our latest results and progress on CO_(2)mineral carbonation are summarised.Also,the possible integration of the iron as a feedstock for iron and steel production will be briefly addressed.An interesting side-effect of this carbon dioxide capture and storage(CCS)route is that significant amounts of iron are obtained from the serpentinite rock material.This is released during the Mg(OH)_(2)production and can be of great interest to the iron-and steel producing sector,which at the same time is Finland’s largest CO_(2)producer.

关键词： mineralisation serpentinite mineral carbonation magnesium carbonate fluidised bed

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Calcium Phosphate Mineralization of Bacteria

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矿物学报 2013年第S1期33卷 6-6页

作者： Anatoly T.Titov Piter M.Larionov Vladimir I.Zaikovskii Institute of Geology and Mineralogy SB RAS Acad.Koptyugav.3NovosibirskRussia Institute of Traumatology and Orthopedy NovosibirskRussia Institute of catalysis of SB RAS NovosibirskRussia

The present work deals with the investigation of mineralization of coccus bacteria infecting human organism, for the Staphylococcus aureus colony as example. The structure and morphology in calcified heard valves and their bioprostheses were investigated.Infectious (septic) endocarditis is characteristic of all the heart valves of this series. About 50 samples of heart valves and their bioprostheses (porcine) subjected to calcium phosphate mineralization were studied. In addition, for more details, we carried out modeling of the ion composition of blood plasma with respect to major elements with the microbial culture of Staphylococcus aureus. In the experiments, a colony of bacteria on solid agar was placed in the aqueous solution with ion concentrations Са = 1.33 mM; Р = 1.5 mM; Mg = 1 mM; NaCl = 0.15 M. The composition of the solution corresponded to the concentrations of ionized elements in the blood of a healthy adult person. The colony of bacteria was in the upper part of the solution.

关键词： mineralisation bacteria hydrohyapatite blood plasma scanning and transmission electron microscopy

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