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Corundum formation by metasomatic reactions in Archean metapelite,SW Greenland:Exploration vectors for ruby deposits within high-grade greenstone belts

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Geoscience Frontiers 2018年第3期9卷 727-749页

作者： Chris Yakymchuk kristoffer szilas Earth and Environmental Sciences University of Waterloo200 University Ave WestWaterlooOntario N2L 3G1Canada Geological Survey of Denmark and Greenland(GEUS) Oter Voldgade 101350 Copenhagen KDenmark

Corundum(ruby-sapphire) is known to have formed in situ within Archean metamorphic rocks at several localities in the North Atlantic Craton of Greenland. Here we present two case studies for such occurrences:(1) Maniitsoq region(Kangerdluarssuk), where kyanite paragneiss hosts ruby corundum, and(2)Nuuk region(Stor?), where sillimanite gneiss hosts ruby corundum. At both occurrences, ultramafic rocks(amphibole-peridotite) are in direct contact with the ruby-bearing zones, which have been transformed to mica schist by metasomatic reactions. The bulk-rock geochemistry of the ruby-bearing rocks is consistent with significant depletion of SiO_2 in combination with addition of Al_2O_3, MgO, K_2O,Th and Sr relative to an assumed aluminous precursor metapelite. Phase equilibria modelling supports ruby genesis from the breakdown of sillimanite and kyanite at elevated temperatures due to the removal of SiO_2. The juxtaposition of relatively silica-and aluminum-rich metasedimentary rocks with low silica ultramafic rocks established a chemical potential gradient that leached/mobilized SiO_2 allowing corundum to stabilize in the former rocks. Furthermore, addition of Al_2O_3 via a metasomatic reaction is required, because Al/Ti is fractionated between the aluminous precursor metapelites and the resulting corundum-bearing mica schist. We propose that Al was mobilized either by complexation with hydroxide at alkaline conditions, or that Al was transported as K-Al-Si-O polymers at deep crustal *** three main exploration vectors for corundum within Archean greenstone belts are:(1) amphiboliteto granulite-facies metamorphic conditions,(2) the juxtaposition of ultramafic rocks and aluminous metapelite, and(3) mica-rich reactions zones at their interface.

关键词： Ultramafic rocks Kyanite Sillimanite Metasomatism Pseudosection Desilicification

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Selective metasomatism of ultramafic cumulates within Archean supracrustal sequences

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Geoscience Frontiers 2024年第5期15卷 283-299页

作者： Lingyu Zhang Sampriti Basak David Zakharov kristoffer szilas Department of Geosciences and Natural Resource Management University of CopenhagenØster Voldgade 101350 CopenhagenDenmark Geological and Environmental Sciences Western Michigan UniversityKalamazooMI 49008USA

The Neoarchean StorøSupracrustal Belt in SW Greenland comprises a sequence of mature quartzite,metapelite,amphibolite,and ultramafic rocks that underwent amphibolite facies metamorphism during the amalgamation of the Mesoarchean Akia Terrane and the Eoarchean Færingehavn *** this belt,tourmaline is found in a transition zone between ultramafic and metapelitic rocks,but also occurs as orbicules within the ultramafic *** tourmaline orbicules hosted by ultramafic rocks are reported for the first time in the North Atlantic craton,thus indicating a unique formation *** conducted a comprehensive examination of the petrology,whole-rock and mineral chemistry,and oxygen isotope compositions from borehole samples in the StorøSupracrustal Belt,to elucidate the metasomatic events associated with the formation of the orbicular *** Storøultramafic rocks have high MgO,Cr,and Ni contents,with low abundances of REE and HFSE,and preserve a typical cumulate *** features are similar to those of ultramafic cumulates found in other Archean supracrustal belts,suggesting a cumulate origin for the Storøultramafic ***,the morphology and composition of the tourmaline orbicules within these cumulates indicate that they originated from melts with high boron and high water concentrations that infiltrated the ultramafic *** main factor influencing the morphology of the tourmaline orbicules is the silicification of the ultramafic rocks,driven by their lower chemical potential of SiO_(2)compared to the surrounding *** silicification process,in combination with compositional variations of cumulates during fractional crystallization,has contributed to the geochemical diversity observed in Archean ultramafic ***,it is crucial to understand the effects of such selective metasomatism on Archean ultramafic rocks,as this will facilitate the extraction of original information preserved in the early rock record.

关键词： Archean Ultramafic rocks Tourmaline Metasomatism Storø Greenland

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Highly refractory Archaean peridotite cumulates:Petrology and geochemistry of the Seqi Ultramafic Complex,SW Greenland

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Geoscience Frontiers 2018年第3期9卷 689-714页

作者： kristoffer szilas Vincent van Hinsberg Iain McDonald Tomas Naeraa Hugh Rollinson Jacob Adetunji Dennis Bird Department of Geological Sciences Stanford University450 Serra MallStanfordCA 94305USA Department of Earth&Planetary Sciences McGill UniversityQuebecCanada Department of Geology Lund UniversitySovegatan 12223 62 LundSweden School of Earth and Ocean Sciences Cardiff UniversityMain BuildingCardiff CF10 3ATUnited Kingdom College of Science University of DerbyDerbyDE22 1GBUK

This paper investigates the petrogenesis of the Seqi Ultramafic Complex, which covers a total area of approximately 0.5 km^2. The ultramafic rocks are hosted by tonalitic orthogneiss of the ca. 3000 Ma Akia terrane with crosscutting granitoid sheets providing an absolute minimum age of 2978 ± 8 Ma for the Seqi Ultramafic Complex. The Seqi rocks represent a broad range of olivine-dominated plutonic rocks with varying modal amounts of chromite, orthopyroxene and amphibole, i.e. various types of dunite(s.s.),peridotite(s.l.), as well as chromitite. The Seqi Ultramafic Complex is characterised primarily by refractory dunite, with highly forsteritic olivine with core compositions having Mg# ranging from about 91 to 93. The overall high modal contents, as well as the specific compositions, of chromite rule out that these rocks represent a fragment of Earth's mantle. The occurrence of stratiform chromitite bands in peridotite, thin chromite layers in dunite and poikilitic orthopyroxene in peridotite instead supports the interpretation that the Seqi Ultramafic Complex represents the remnant of a fragmented layered complex or a magma conduit, which was subsequently broken up and entrained during the formation of the regional continental *** all of the characteristics of the Seqi Ultramafic Complex points to formation of these highly refractory peridotites from an extremely magnesian(Mg# ~ 80), near-anhydrous magma, as olivinedominated cumulates with high modal contents of chromite. It is noted that the Seqi cumulates were derived from a mantle source by extreme degrees of partial melting(>40%). This mantle source could potentially represent the precursor for the sub-continental lithospheric mantle(SCLM) in this region,which has previously been shown to be ultra-depleted. The Seqi Ultramafic Complex, as well as similar peridotite bodies in the Fiskefjord region, may thus constitute the earliest cumulates that formed during the large-scale melting event(s), which

关键词： North Atlantic Craton Archaean Dunite Platinum-group elements Ultra-depleted mantle Fiskefjord

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Zircon within chromitite requires revision of the tectonic history of the Eoarchean Itsaq Gneiss complex,Greenland

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Geoscience Frontiers 2023年第6期14卷 273-285页

作者： Hikaru Sawada Tomoaki Morishita Adrien Vezinet Richard Stern Kenichiro Tani Ikuya Nishio Kanta Takahashi D.Graham Pearson kristoffer szilas Department of Earth System Science University of ToyamaToyamaJapan X-Star Japan Agency for Marine-Earth Science and Technology(JAMSTEC)KanagawaJapan Faculty of Geosciences and Civil Engineering Kanazawa UniversityKanazawaJapan Lamont-Doherty Earth Observatory Columbia UniversityPalisadesUSA Volcanoes and Earth’s Interior Research Center JAMSTECKanagawaJapan Department of Earth and Atmospheric Sciences University of AlbertaEdmontonCanada Canadian Centre for Isotopic Microanalysis University of AlbertaEdmontonCanada National Museum of Nature and Science TsukubaJapan Department of Geosciences and Natural Resource Management University of CopenhagenCopenhagenDenmark

The Ujaragssuit Nunat layered(UNL)unit in the Itsaq Gneiss Complex,west Greenland,has been consid-ered to contain one of the oldest chromitites on Earth based on~ca.4.1 Ga Hadean whole rock Pt-Os model ages and ca.3.81 Ga zircon U-Pb age of the surrounding *** study obtained zircon from the chromitite within this unit as well as granitoid sheets that intruded into the UNL ***-situ U-Pb-Hf-O isotope measurements were made on the *** from both the chromitite and the intrusive granitoids show concordant U-Pb ages of ca.2.97-2.95 *** contrast,Hf and 0 isotopic anal-yses indicate that zircons in the chromitites have a different origin from those in the intrusive *** from granitoids yielded Th/U ratios higher than 0.2,initial Hf isotope ratios of 0.2805-0.2807(i.e,initial:Hf value of-11 to-5),andδ^(18)O values of mostly 6.0‰-7.0‰,which are typical for felsic igneous rocks in Archean continental *** least altered zircons from a chromitite exhibited initial Hf isotope ratios of 0.28078-0.28084(i.e.,initial:Hf value of-1.1 to-0.4),close the chondritic value at ca.3.0 Ga and the depleted mantle at ca.3.2 *** zircons also haveδ^(18)O values of 4.2‰6.1‰which correspond to typical mantle *** other chromitite zircons yielded Th/U ratios lower than 0.1,and Hf and 0 isotopic compositions ranging between the least altered zircons and the intrusive granitoid *** results indicate that the zircons in the chromitites crystallized before or during the 2.97-2.95 Ga granitoid intrusion and most of the zircons were altered by subsequent ***,the present results suggest that zircons in the chromitites originally had depleted Hf iso-topic compositions at ca.3.2-3.0 *** can be explained by two different models of the evolution of the UNL *** is that if the UNL unit was formed at>3.81 Ga as previously thought,with the zircons in the chromitites subsequently being precipitated by ca.3.2-2.95 G

关键词： Archean Itsaq gneiss complex Ultramafic rock Metasomatism

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Deserpentinization and high-pressure(eclogite-facies) metamorphic features in the Eoarchean ultramafic body from Isua,Greenland

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Geoscience Frontiers 2022年第1期13卷 297-309页

作者： Juan Miguel Guotana Tomoaki Morishita Ikuya Nishio Akihiro Tamura Tomoyuki Mizukami Kenichiro Tani Yumiko Harigane kristoffer szilas D.Graham Pearson Graduate School of Natural Science&Technology Kanazawa UniversityJapan School of Environmental Science and Management University of the Philippines Los BañosLagunaPhilippines Lamont-Doherty Earth Observatory Columbia UniversityPalisadesNY 10964USA Volcanoes and Earth’s Interior Research Center Japan Agency for Marine-Earth Science and Technology2-15 NatsushimaKanagawa 237-0061Japan National Museum of Nature and Science 4-1-1AmakuboTsukuba-shiIbaraki 305-0005Japan Institute of Geology and Geoinformation Geological Survey of Japan/AIST Central 71-1-1 HigashiTsukubaIbaraki 305-8567Japan Department of Geosciences and Natural Resource Management University of CopenhagenØster Voldgade 101350 CopenhagenDenmark Department of Earth&Atmospheric Sciences University of AlbertaEdmontonABCanada

Discontinuous chains of ultramafic rock bodies form part of the 3800–3700 Ma Isua Supracrustal Belt(ISB),hosted in the Itsaq Gneiss Complex of southwestern *** bodies are among the world’s oldest outcrops of ultramafic rocks and hence an invaluable geologic *** rocks from Lens B in the northwestern limb of ISB show characteristics of several stages of serpentinization and deserpentinization forming prograde and retrograde mineral ***-rich humite-group minerals such as titanian chondrodite(Ti-Chn)and titanian clinohumite(Ti-Chu)often occur as accessory phases in the metamorphosed ultramafic *** Ti-rich humite minerals are associated with metamorphic *** host olivine is highly forsteritic(Fo96-98)with variable Mn O and Ni O *** concentrations of the rare-earth elements(REE)and high-field strength elements(HFSE)of the metamorphic olivine are higher than typical mantle *** textural and chemical characteristics of the olivine indicate metamorphic origin as a result of deserpentinization of a serpentinized ultramafic protolith rather than primary assemblage reflecting mantle residues from high-degrees of partial *** close association of olivine,antigorite and intergrown Ti-Chn and Ti-Chu suggests pressure condition between$1.3–2.6 GPa within the antigorite stability field(<700°C).The overall petrological and geochemical features of Lens B ultramafic body within the Eoarchean ISB indicate that these are allochthonous ultramafic rocks that recorded serpentine dehydration at relatively lower temperature and reached eclogite facies condition during their complex metamorphic history similar to exhumed UHP ultramafic rocks in modern subduction zone channels.

关键词： Titanian chondrodite Titanian clinohumite Isua supracrustal belt UHP Deserpentinization

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太古宙绿岩带中铬铁矿床研究现状与展望

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岩石学报 2023年第12期39卷 3734-3758页

作者：王嘉玮蔡鹏捷 szilas kristoffer 连东洋杨经绥中国地质大学(北京) 北京100083 中国地质科学院矿产资源研究所自然资源部成矿作用与资源评价重点实验室北京100037 内生金属矿床成矿机制研究国家重点实验室南京大学地球科学与工程学院南京210023 哥本哈根大学地球科学与自然资源学院哥本哈根1350 地幔研究中心自然资源部深地动力学实验室中国地质科学院地质研究所北京100037

太古宙绿岩带中铬铁矿床不仅具有重要经济价值,而且是研究地球早期物质组成和地幔演化的重要对象。太古宙铬铁矿床形成时代久远,普遍经历了后期复杂的变质、变形和流体改造等一系列地质作用。相较于显生宙豆荚状铬铁矿和元古宙层状铬铁... 详细信息

太古宙绿岩带中铬铁矿床不仅具有重要经济价值,而且是研究地球早期物质组成和地幔演化的重要对象。太古宙铬铁矿床形成时代久远,普遍经历了后期复杂的变质、变形和流体改造等一系列地质作用。相较于显生宙豆荚状铬铁矿和元古宙层状铬铁矿,对太古宙绿岩带内产出铬铁矿的研究还较为薄弱,尤其对铬铁矿体形成的地质背景和岩浆作用缺乏深入系统的研究。本文综述了格陵兰、印度、澳大利亚西部、加拿大以及津巴布韦等典型太古宙绿岩带中铬铁矿床的主要地质特征和研究现状,讨论了相关科学问题和研究展望。绿岩带中铬铁矿床主要产在古太古代-新太古代(3.3~2.7Ga)克拉通内的超基性岩石单元中,矿体常与蛇纹石化纯橄岩伴生。铬铁矿体产状复杂,既有层状和似层状,也有透镜状和不规则状,因此不能简单归于层状铬铁矿或豆荚状铬铁矿。铬铁矿岩以块状为主,其铬铁矿Cr#相对较高(>60),属高铬型,Mg#中等偏高(21~93)且与Cr#呈负相关关系。研究认为,绿岩带中铬铁矿的成矿母岩浆来自深部亏损含水地幔分异所形成的科马提质岩浆,且受到了地壳物质混染。在开放的岩浆房内,含矿原始母岩浆与不断补给的科马提质岩浆相混合,并随着岩浆的重力分异和对流分层等作用形成堆晶状铬铁矿体。

关键词：铬铁矿铬铁矿岩太古宙绿岩带科马提岩

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太古宙铬铁矿床研究概述

太古宙铬铁矿床研究概述

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第十届全国成矿理论与找矿方法学术讨论会

作者：王嘉玮杨经绥蔡鹏捷 kristoffer szilas 连东洋中国地质科学院矿产资源研究所自然资源部成矿作用与资源评价重点实验室南京大学地球科学与工程学院内生金属矿床成矿机制研究国家重点实验室哥本哈根大学地球科学与自然资源学院

铬(Cr)金属因其具有优异的耐高温和抗腐蚀等特性,广泛应用于航空航天等高端制造业领域(杨经绥等,2010)。铬铁矿[chromite,(Fe2+Mg)Cr2O4]为含Cr元素的主要矿物,立方晶系,属尖晶石族,是自然界提取工业铬金属的唯一来源(Irvine,1965)。铬...

铬(Cr)金属因其具有优异的耐高温和抗腐蚀等特性,广泛应用于航空航天等高端制造业领域(杨经绥等,2010)。铬铁矿[chromite,(Fe2+Mg)Cr2O4]为含Cr元素的主要矿物,立方晶系,属尖晶石族,是自然界提取工业铬金属的唯一来源(Irvine,1965)。铬在我国属于紧缺的战略性矿产资源,对其的需求高度依赖进口,随着我国产业转型升级,缓解铬铁矿供需矛盾迫在眉睫(杨经绥等,2022)。

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Disaster Knowledge Gaps: Exploring the Interface Between Science and Policy for Disaster Risk Reduction in Europe

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International Journal of Disaster Risk Science 2020年第1期11卷 1-12页

作者： kristoffer Albris Kristian Cedervall Lauta Emmanuel Raju Department of Anthropology Faculty of Social Scienceand COPE–Copenhagen Center for Disaster ResearchUniversity of Copenhagen1353 CopenhagenDenmark Center for International Law Conflict and CrisisFaculty of Lawand COPE–Copenhagen Center for Disaster ResearchUniversity of Copenhagen2300 CopenhagenDenmark Global Health Section Faculty of Health and Medical Scienceand COPE–Copenhagen Center for Disaster ResearchUniversity of Copenhagen1353 CopenhagenDenmark African Centre for Disaster Studies Unit for Environmental Sciences and ManagementNorth-West UniversityPotchefstroom 2531South Africa

Expert scientific knowledge is fast becoming an integral part of disaster management, and, in the process, is changing the role of science for the reduction of disaster risks at the policy level. Yet science and policy operate in different domains between which there are often competing interests and modes of valuing knowledge. Based on research done as part of the research project Enhancing Synergies for Disaster Prevention in the European Union(ESPREssO), we discuss three major issues facing European Union member states with respect to the interface between science and policy for disaster risk reduction:knowledge transfer, disaster expertise, and risk *** doing so, we hone in on three gaps: an epistemological gap, an institutional gap, and a strategic gap. We argue that these gaps can help explain underlying systematic challenges for the integration between science and policy for disaster risk reduction. These gaps need to be addressed by focusing on changes at the governance level.

关键词： Disaster governance Disaster risk reduction Europe Knowledge sharing Risk expertise Science-policy interface

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How to package and SEND mRNA: a novel “humanized” vector system based on endogenous retroviruses

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Signal Transduction and Targeted Therapy 2021年第12期6卷 3367-3368页

作者： kristoffer Riecken Dawid Głów Boris Fehse Research Dept.Cell&Gene Therapy Dept.of Stem Cell TransplantationUniversity Medical Centre Hamburg-Eppendorf(UKE)Hamburg 20246Germany

A recent publication in Science describes a novel mRNA delivery system termed SEND,entirely consisting of endogenous proteins.1 These virus-like particles(VLPs),able to deliver mRNA of e.g.,Cas9,represent a new class of gene transfer *** development of efficient,specific,and safe vectors for the delivery of nucleic acids and proteins remains one of the biggest challenges in gene therapy,particularly for in vivo *** currently preferred viral vectors have several limitations,including biosafety issues,laborious and expensive manufacture,as well as the impossibility of multiple applications due to the inherent immunogenicity of viral *** contrast,non-viral vectors are much easier to produce on a large scale,but have not yet reached gene transfer rates comparable with viral vectors.

关键词： endogenous system entirely

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In Situ Mineralization of Biomass-Derived Hydrogels Boosts Capacitive Electrochemical Energy Storage in Free-Standing 3D Carbon Aerogels

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Energy & Environmental Materials 2024年第2期7卷 359-371页

作者： Anjali Achazhiyath Edathil Babak Rezaei kristoffer Almdal Stephan Sylνest Keller National Centre for Nano Fabrication and Characterization DTU NanolabTechnical University of Denmark2800LyngbyDenmark DTU Chemistry Technical University of Denmark2800LyngbyDenmark

Here,a novel fabrication method for making free-standing 3D hierarchical porous carbon aerogels from molecularly engineered biomass-derived hydrogels is *** situ formed flower-like CaCO_(3)molecularly embedded within the hydrogel network regulated the pore structure during in situ mineralization assisted one-step activation graphitization(iMAG),while the intrinsic structural integrity of the carbon aerogels was *** homogenously distributed minerals simultaneously acted as a hard template,activating agent,and graphitization *** decomposition of the homogenously distributed CaCO_(3)during iMAG followed by the etching of residual CaO through a mild acid washing endowed a robust carbon aerogel with high porosity and excellent electrochemical *** 0.5 mA cm^(-2),the gravimetric capacitance increased from 0.01 F g^(-1)without mineralization to 322 F g^(-1)with iMAG,which exceeds values reported for any other free-standing or powder-based biomass-derived carbon *** outstanding cycling stability of~104%after 1000 cycles in 1 M HClO4 was *** assembled symmetric supercapacitor device delivered a high specific capacitance of 376 F g^(-1)and a high energy density of 26 W h kg^(-1)at a power density of 4000 W kg^(-1),with excellent cycling performance(98.5%retention after 2000 cycles).In combination with the proposed 3D printed mold-assisted solution casting(3DMASC),iMAG allows for the generation of free-standing carbon aerogel architectures with arbitrary ***,the novel method introduces flexibility in constructing free-standing carbon aerogels from any ionically cross-linkable biopolymer while maintaining the ability to tailor the design,dimensions,and pore size distribution for specific energy storage applications.

关键词： biomass carbon aerogel sustainable energy materials free-standing supercapacitors

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