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Seeing through the magnetite:Reassessing Eoarchean atmosphere composition from Isua(Greenland) ≥3.7 Ga banded iron formations

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Geoscience Frontiers 2017年第6期8卷 1233-1240页

作者： Allen P.Nutman Vickie C.Bennett Clark R.L.Friend GeoQuEST Research Centre School of Earth and Environmental SciencesUniversity of WollongongWollongongNSW 2522Australia Research School of Earth Sciences Australian National UniversityCanberraACT 0200Australia Glendale TiddingtonOxonOX9 2LQUK

Estimates of early atmosphere compositions from metamorphosed banded iron formations(BIFs)including the well-studied ≥3.7 BIFs of the Isua supracrustal belt(Greenland)are dependent on knowledge of primary versus secondary Fe-mineralogical *** new observations from locally well preserved domains,we interpret that a previously assumed primary redox indicator mineral,magnetite,is secondary after sedimentary Fe-clays(probably greenalite)±*** ~3.7 Ga Isua BIF,pre-tectonic nodules of quartz+Fe-rich amphibole±calcite reside in a finegrained(≤100 μm)quartz+magnetite *** interpret the Isua nodule amphibole as the metamorphosed equivalent of primary Fe-rich clays,armoured from diagenetic oxidative reactions by early silica ***,in another low strain lacunae,~3.76 Ga BIF layering is not solid magnetite but instead fine-grained magnetite+quartz *** magnetite+quartz aggregates are interpreted as the metamorphosed equivalent of Fe-clay-rich layers that were oxidised during diagenesis,because they were not armoured by early *** almost all Isua BIF exposures,this evidence has been destroyed by strong ductile *** Fe-clays likely formed by abiotic reactions between aqueous Fe^(2+)and *** clays along with silica±carbonate were deposited below an oceanic Fe-chemocline as the sedimentary precursors of *** of the clays on the sea floor may have been by anaerobic oxidation of Fe^(2+),a mechanism compatible with iron isotopic data previously published on these *** new determinations of the primary redoxsensitive Fe-mineralogy of BIF significantly revise estimates of early Earth atmospheric oxygen and CO_2 content,with formation of protolith Fe-rich clays and carbonates compatible with an anoxic Eoarchean atmosphere with much higher CO_2 levels than previously estimated for Isua and in the present-day atmosphere.

关键词： banded iron formation Eoarchean Early atmosphere Greenalite Magnetite

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Silicon Isotopic Compositions of Archean banded Si-Fe Formation (BIF)in the Gongchangling Ore Deposit, Liaoning Province, China

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Science China Chemistry 1993年第4期36卷 482-489页

作者：蒋少涌丁悌平万德芳李延河 Institute of Mineral Deposits Chinese Academy of Geological Sciences Beijing 100037 PRC

The results of silicon isotope analyses of Precambrian BIF are reported for the first time. The δ^(30)Si values of magnetite-quartzite in the Gongchangling ore deposit are between —0.9 and —2.2‰, which are obviously different from those in host rocks (0.2——0.6‰). It is suggested that the BIF may be a product of chemical precipitation in Archean submarine hydrothermal environment. There is a possibility of using silicon isotopes to distinguish the protolith of metamorphic rocks and trace the origin of silicon of altered minerals.

关键词： silieon isotope banded iron formation (BIF) Gongehanffling China.

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DISCOVERY OF banded TOURMALINITE AND MINERALIZED TOURMALINE-RICH CHEMICAL SEDIMENTARY ROCKS FROM STRATABOUND AND STRATIFORM COPPER DEPOSITS IN ZHONGTIAOSHAN DISTRICT, SHANXI PROVINCE

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Chinese Science Bulletin 1989年第10期34卷 846-851页

作者：孙海田葛朝华 Institute of Mineral Deposits Chinese Academy of Geological Sciences Beijing

The banded or laminated exhalative hydrothermal chemical tourmalinite and mineralized tourmaline-rich sedimentary rocks were recognised for the first time in the stratabound and stratiform copper deposits in ghongtiaoshan District in 1986, and further confirmed by the intensive investigations. The discovery can help better understand the geological environments and the origin of the stratabound and stratiform copper deposits.

关键词： the lower-middle Proterozoic stratabound and stratiform copper deposits banded tourmalinite.

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STUDIES ON THE FORMATION AND RELAXATION OF banded STRUCTURE OF LIQUID CRYSTALLINE COPOLYESTER B-ET

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Chinese Science Bulletin 1990年第16期35卷 1351-1354页

作者：董炎明 Department of Chemistry Xiangtan University Xiangtan 411105 PRC

banded structure of thermotropic liquid crystalline polymers has been widely characterized under light and electron microscopy. It occurs in oriented films of most liquid crystalline polyesters. The structure of specific orientation state on nematic phase is considered to he related to the high strength and high modulus of products. This note focuses

关键词： copolyester liquid crystal banded structure.

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Modelling Textural Anisotropy of Magnetic Susceptibility of banded Iron Formations

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Journal of Applied Mathematics and Physics 2015年第4期3卷 405-410页

作者： William W. Guo School of Engineering & Technology Central Queensland University North Rockhampton Australia

Anisotropy of magnetic susceptibility (AMS) of banded iron formations (BIFs) is characterized by high anisotropy and well-developed bedding-parallel magnetic foliation. Since most previous studies were focused on palaeomagneism of BIFs and BIF-derived iron ores, little effort has been made to further understand this special type of AMS for BIFs. A detailed theoretical analysis, incorporating with the previous experimental data, is made to understand the formative mechanism of this special anisotropy for BIFs. The good consistence between the theoretical and experimental results demonstrates that this type of anisotropy is likely caused by the layered structure of BIFs, and thus verifies the term of textural anisotropy for BIFs. Theoretical analysis also shows that in the negligence of the inter-layer magnetic action BIF’s apparent anisotropy increases with an increase in intrinsic susceptibility of magnetic layers, but decreases with an increase in length-to- diameter ratio of the magnetic layer.

关键词： Textural Anisotropy of Magnetic Susceptibility (AMS) banded Iron Formation (BIF) Theoretical and Experimental Modelling Hamersley Province

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Life on Earth Originated Where Later Microbial Oxygenic Photosynthesis Precipitated banded Iron Formation, Suppressing Life Diversification for 1.4 Ga

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International Journal of Geosciences 2013年第10期4卷 1382-1391页

作者： Zeev Lewy Geological Survey of Israel Jerusalem Israel

The earliest Precambrian microbial structures appear in successions with banded iron formations (BIF) suggesting genetic relationships. The hypothesis of the deep ocean origin of BIFs associated with Mid-Ocean Ridge (MOR) like features seems to have been recently supported by the discovery of peculiar microbial ecosystems with unique faunal assemblages restricted to these volcanic vents. However, new sedimentological evidence points to the accumulation of varved BIF in huge, very shallow lakes of hydrothermal-water situated on continental plates while passing through thePolar Regions, where UV radiation is minimal. The mineral-rich solutions seeped from numerous fumaroles, providing suitable conditions for chemical reactions between inorganic components, incidentally creating organic-like self-multiplying molecules long before the biologically-initiated BIF deposition. Some of these early chemoautotrophic prokaryotes developed oxygenic photosynthesis during half a year of solar illumination. The released oxygen formed iron oxides and carbonates deposited with amorphous silica (geyserite) in laminae as BIF during 3.8 - 1.9 Ga. BIF deposition consumed most of the photosynthetic oxygen for 1.4 billion years. Intensified cyanobacteria oxygenic photosynthesis during 2.4 - 2.2 Ga raised the atmospheric oxygen content (Great Oxidation Event) over the Polar Regions, forming an oxygen-ozone shield against UV radiation. It gradually extended to lower latitudes, enabling prokaryotes to leave their ecologically stable habitat and acclimatize in new ecosystems, where they diversified, leading to eukaryote evolution. The 231/2° inclination of Earth’s rotation axis differentiated the solar effect on the Polar Regions, which controlled life evolution on Earth, as well as on planet Mars (25° inclination), where life probably did not evolve beyond early prokaryotes.

关键词： Early Precambrian Earth Life Cradles banded Iron Formation (BIF) 1.4 Ga Suppressed Life Diversification Life on Mars

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Comment on “Integrated Mineralogical Characterization of banded Iron Ores of Orissa and Its Implications on Beneficiation” by Mohanty <i>et al</i>. (2012), Journal of Minerals and Materials Characterization and Engineering, 11, 1133-1142

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Journal of Minerals and Materials Characterization and Engineering 2013年第5期1卷 280-283页

作者： Pranaba K. Nayak Tata Institute of Fundamental Research Mumbai India

Mohanty et al. (2012) have wrongly analyzed M?ssbauer spectra obtained from various iron ore samples. We criticized their approach suggesting suitable methodology, and suggested to refer earlier work carried out by Na... 详细信息

关键词： Mossbauer Spectroscopy banded Iron Formation Goethite Magnetite Hematite

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Gastric Bezoar after Vertical banded Gastroplasty: A Case Report and Review of the Literature

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Surgical Science 2011年第5期2卷 242-245页

作者： Abdul S. Bangura Stelin Johnson Karen E. Gibbs 不详

Gastric bezoars are uncommon in the bariatric surgery population. Though popular in earlier decades, the Vertical banded Gastroplasty (VBG) is no longer a staple procedure in the United States. It has been supplanted by the Roux-en-Y gastric bypass (RYGBP) and the laparoscopic adjustable gastric band (LAGB) as the most commonly performed bariatric procedures. However, there are many patients who have previously undergone VBGs, and may present with associated complications. We present a case of a gastric obstruction caused by a bezoar in a patient who had a VBG fifteen years prior to presentation.

关键词： Vertical banded Gastroplasty Bariatric Surgery Bezoar Obstruction

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Long-term results after revisions of failed primary vertical banded gastroplasty

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World Journal of Gastrointestinal Surgery 2016年第3期8卷 238-245页

作者： Martin R van Wezenbeek Frans J F Smulders Jean-Paul J G M de Zoete Misha D Luyer Gust van Montfort Simon W Nienhuijs Department of Surgery Catharina Hospital

AIM: To compare the results after revision of primary vertical banded gastroplasty(Re-VBG) and conversion to sleeve gastrectomy(cS G) or gastric bypass(cR YGB).METHODS: In this retrospective single-center study, all patients with a failed VBG who underwent revisional surgery were included. Medical charts were reviewed and additional postal questionnaires were sent to update follow-up. Weight loss, postoperative complications and long-term outcome were assessed. RESULTS: A total 152 patients were included in this study, of which 21 underwent Re-VBG, 16 underwent c SG and 115 patients underwent c RYGB. Sixteen patients necessitated a second revisional procedure. No patients were lost-to-follow-up. Two patients deceased during the follow-up period, 23 patients did not return the questionnaire. Main reasons for revision were dysphagia/vomiting, weight regain and insufficient weight loss. Excess weight loss(%EWL) after Re-VBG, cS G and cR YGB was, respectively, 45%, 57% and 72%. Eighteen patients(11.8%) reported postoperative complications and 27% reported long-term complaints. CONCLUSION: In terms of additional weight loss, postoperative complaints and reintervention rate, Rouxen-Y gastric bypass seems feasible as a revision for a failed VBG.

关键词： Vertical banded gastroplasty Conversion Revision Gastric bypass Sleeve gastrectomy Additional weight loss

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Structures and growth mechanisms of poly-(3-hydroxybutyrate) (PHB) crystallized from solution and thin melt film

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Science China Chemistry 2008年第9期51卷 853-858页

作者： CAO QiKun QIAO XiaoPing WANG Hui LIU JiePing Department of Chemistry Huaibei Coal Industry Teachers CollegeAnhui 235000China

The spherulitic structures and morphologies of poly-(3-hydroxybutyrate) (PHB) crystallized from a so- lution and a thin melt film were investigated in this study. The formation mechanisms of banded spherulites under different crystallization conditions are proposed. It was found that the formation of banded spherulites was caused by the rhythmic crystal growth of the spherulites and lamellar twisting growth for the polymer crystallization from a thin melt film and a solution, respectively.

关键词： rhythmic crystal growth lamellar twisting banded spherulite poly(3-hydroxybutyrate)

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