scholarly journals Petrography and Shock Metamorphism of the Lunar Breccia Meteorite NWA 13120

Minerals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 899
Author(s):  
Zhipeng Xia ◽  
Bingkui Miao ◽  
Chuantong Zhang ◽  
Hongyi Chen ◽  
Lanfang Xie ◽  
...  
Keyword(s):  
Lunar Surface ◽  
Lunar Regolith ◽  
Evolutionary Process ◽  
Strong Shock ◽  
Shock Metamorphism ◽  
Parent Rock ◽  
Impact Melt ◽  
Fine Grained ◽  
The Matrix ◽  
Post Shock

Lunar meteorites are the fragments of rocks that fell on Earth because of the impacts of asteroids on the Moon. Such rocks preserve information about the composition, evolutionary process, and shock history of the lunar surface. NWA 13120 is a recently discovered lunar breccia meteorite having features of strong shock, which is composed of lithic and mineral clasts in a matrix of very fine-grained (<10 μm) and recrystallized olivine-plagioclase with a poikilitic-like texture. As the most abundant lithic clasts, the crystalline impact melt (CIM) clasts can be divided into four types according to their texture and mineral composition: (1) anorthosites or troctolitic anorthosite with a poikilitic-like texture, but the mineral content is different from that of the matrix; (2) anorthosites containing basaltic fragments and rich in vesicles; (3) troctolitic anorthosite containing metamorphic olivine mineral fragments; (4) troctolitic anorthosite containing troctolite fragments. Based on the petrology and mineralogy, NWA 13120 is a lunar meteorite that was derived from the ferrous anorthosite suite (FANs) of the lunar highlands, while its texture suggests it is a crystalline impact melt breccia. In addition, we infer that the parent rock of NWA 13120 is a lunar regolith breccia enriched in glass fragments. During the shock process, at pressures of more than 20 GPa, all plagioclase fragments were transformed into maskelynites, and olivine fragments occurred metamorphism. The post-shock temperature led to the partial melting of the basaltic fragments. Subsequently, all glass with diverse components in the parent rock were devitrified and recrystallized, forming the common olivine-plagioclase poikilitic-like texture and different CIM clasts. Meanwhile, the devitrification of maskelynite formed the accumulation of a large number of plagioclase microcrystals. Therefore, NWA 13120 is a meteorite of great significance for understanding the local shock metamorphism of lunar rocks on the lunar surface.

Microstructure of Friction Stir Processed Mg-Y-Zn Alloy

2007 ◽  
Vol 558-559 ◽  
pp. 777-780 ◽  
Author(s):  
Taiki Morishige ◽  
Masato Tsujikawa ◽  
Sung Wook Chung ◽  
Sachio Oki ◽  
Kenji Higashi
Keyword(s):  
Equal Channel Angular Extrusion ◽  
Second Phase ◽  
Ingot Metallurgy ◽  
Friction Stir ◽  
Fine Grained ◽  
Probe Diameter ◽  
Fine Grain ◽  
Second Phase Particles ◽  
The Matrix ◽  
Zn Alloy

Friction stir processing (FSP) is the effective method of the grain refinement for light metals. The aim of this study is to acquire the fine grained bulk Mg-Y-Zn alloy by ingot metallurgy route much lower in cost. Such bulk alloy can be formed by the superplastic forging. The microstructure of as-cast Mg-Y-Zn alloy was dendrite. The dendrite arm spacing was 72.5 [(m], and there are the lamellar structures in it. FSP was conducted on allover the plate of Mg-Y-Zn alloy for both surfaces by the rotational tool with FSW machine. The stirring passes were shifted half of the probe diameter every execution. The dendrite structures disappeared after FSP, but the lamellar structure could be observed by TEM. The matrix became recrystallized fine grain, and interdendritic second phase particles were dispersed in the grain boundaries. By using FSP, cast Mg-Y-Zn alloy could have fine-grained. This result compared to this material produced by equal channel angular extrusion (ECAE) or rapid-solidified powder metallurgy (RS P/M). As the result, as-FSPed material has the higher hardness than materials produced by the other processes at the similar grain size.

scholarly journals PESTRÉ SEDIMENTY OTTNANGU V BRNĚ-KOHOUTOVICÍCH

2018 ◽  
Vol 25 (1-2) ◽  
Author(s):  
Pavla Tomanová Petrová ◽  
David Buriánek ◽  
Karel Kirchner ◽  
Oldřich Krejčí ◽  
František Laufek ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Clay Minerals ◽  
Heavy Fraction ◽  
Parent Rock ◽  
Fine Grained ◽  
Sediment Layers

The reddish coloured sediment layers (up to 5 m thick) were found within building pit in the Brno-Kohoutovice on the Libušina třída Avenue (NW part of Brno). These sediments were assigned to the Ottnangian based on characteristic pseudoassociation of microfossils. Smectite or illite/smectite dominates over kaolinite among the clay minerals. Minerals typomorphic for granitoids of the Brno Massif, i.e. epidote, amphibole and altered titanite, absolutely dominate (99 mod. %) within the assemblage of translucent heavy fraction. Minerals like garnet and staurolite which are typical for the Ottnangian sediments in this region, are presented only in accessoric amount. The chemical composition of the studied sediments is located between the chemical composition of granodiorites of the Brno Massif and Neogene clays. Relatively high content of Zr, Hf and HREE, which is interpreted as result of presence of very fine grained zircon in studied sediments, is characteristic. High content of SiO2 and comparatively low contents of Al2O3 and Fe2O3 indicates non-lateritic type of weathering. The chemical composition of studied sediments reflects semiarid to humid paleoclimate that the granitoids of the Brno Massif as parent rock have undergone.

Age and Geochemical Studies of the Snyder Breccia, Coastal Labrador

1975 ◽  
Vol 12 (3) ◽  
pp. 361-370 ◽  
Author(s):  
Jackson M. Barton Jr. ◽  
Erika S. Barton
Keyword(s):  
Trace Element ◽  
North Atlantic ◽  
Layered Intrusion ◽  
Basement Complex ◽  
Fine Grained ◽  
The North ◽  
Isotopic Analyses ◽  
The Matrix ◽  
The North Atlantic ◽  
Geochemical Studies

The Snyder breccia is composed of angular to subrounded xenoliths of migmatites and amphibolites in a very fine grained matrix. It is apparently intrusive into the metasediments of the Snyder Group exposed at Snyder Bay, Labrador. The Snyder Group unconformably overlies a migmatitic and amphibolitic basement complex and is intruded by the Kiglapait layered intrusion. K–Ar ages indicate that the basement complex is Archean in age (> 2600 m.y. old) and that the Kiglapait layered intrusion was emplaced prior to 1280 m.y. ago. Major and trace element analyses of the matrix of the Snyder breccia indicate that while it was originally of tonalitic composition, later it locally underwent alteration characterized by loss of sodium and strontium and gain of potassium, rubidium and barium. Rb–Sr isotopic analyses show that this alteration occurred about 1842 m.y. ago, most probably contemporaneously with emplacement of the breccia. The Snyder Group thus was deposited sometime between 2600 and 1842 m.y. ago and may be correlative with other Aphebian successions preserved on the North Atlantic Archean craton.

Composition, technology and provenance of Roman pottery fromNapoca(Cluj-Napoca, Romania)

Clay Minerals ◽  
2018 ◽  
Vol 53 (4) ◽  
pp. 621-641 ◽  
Author(s):  
Ágnes Gál ◽  
Corina Ionescu ◽  
Mátyás Bajusz ◽  
Vlad A. Codrea ◽  
Volker Hoeck ◽  
...  
Keyword(s):  
Middle Miocene ◽  
Raw Materials ◽  
Ceramic Body ◽  
Polarized Light ◽  
Raw Material ◽  
Gradual Transition ◽  
X Ray ◽  
Fine Grained ◽  
The Matrix ◽  
Technological Constraints

ABSTRACTSecond-century CE (common era) household pottery sherds found in the city ofNapoca(present day Cluj-Napoca, Romania) in Roman Dacia were investigated by polarized light optical microscopy, X-ray powder diffraction, Fourier-transform infrared spectroscopy and cold field emission scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy to obtain information on technology, raw materials and site of production. Compositionally, all samples are similar with comparable fine and semi-fine microstructures and oriented microtextures. Optically, there is a gradual transition from microcrystalline to an amorphous illitic-muscovitic matrix. The small aplastic inclusions are mostly quartz and feldspar. Fine-grained carbonate aggregates are distributed inhomogeneously in the ceramic body. Well-preserved Middle Miocene foraminifera tests are characteristic of the ceramics. The gradual thermal changes of the matrix and the newly formed phases upon firing, such as ‘ceramic melilite’, Fe-gehlenite, clinopyroxene, glass, hematite and some maghemite support inferences regarding the technological constraints in producing the pottery. The firing took place in a mostly oxidizing atmosphere and the temperature extended from at least 850°C to >900°C. The Middle Miocene marly clay from the area surrounding the site shows similar mineralogical and micropalaeontological contents to those of the ceramic specimens and is the best candidate for the raw material used for local production of the Roman pottery.

The Microstructure and Superplastic Behavior of Clean Mechanically Alloyed Titanium–Titanium Boride Alloys

1999 ◽  
Vol 601 ◽  
Author(s):  
A.P. Brown ◽  
R Brydson ◽  
C. Hammond ◽  
A. Wisbey ◽  
T.M.T. Godfrey
Keyword(s):  
Sheet Material ◽  
Hot Isostatic Pressing ◽  
Superplastic Forming ◽  
Titanium Boride ◽  
Production Cycle ◽  
Microstructural Development ◽  
Mechanically Alloyed ◽  
Boron Powder ◽  
Fine Grained ◽  
The Matrix

AbstractThe superplastic forming (SPF) of titanium alloys is an established technology. A reduction in grain size from that of the typical sheet materials would lead to enhanced SPF properties and hence a reduction in production cycle times. This study describes the microstructural development and superplastic behaviour of fine-grained Ti-6%Al-4%V alloys. Ball-milling Ti-6%Al-4%V powder produces a nanocrystalline material; however on consolidation by hot isostatic pressing rapid grain growth occurs. Addition of boron powder during milling leads to boride precipitates in the matrix of the consolidated alloy. The precipitates are dispersed inhomogeneously, resulting in localized grain refinement. Superplastic testing revealed cavitation formation but in comparison to conventional sheet material, large elongations were achieved at relatively high strain rates.

Mineral assemblages and xenolith cargo in the Storkwitz carbonatite (Delitzsch Complex, Germany)

2020 ◽  
Author(s):  
Hripsime Gevorgyan ◽  
Sascha Schmidt ◽  
Ilja Kogan ◽  
Manuel Lapp
Keyword(s):  
Late Cretaceous ◽  
Early Stage ◽  
Soft Rock ◽  
Core Material ◽  
Compositional Variation ◽  
Published Data ◽  
Fine Grained ◽  
Ultramafic Lamprophyre ◽  
The Matrix ◽  
History Of

&lt;p&gt;The multi-compositional carbonatite body of Storkwitz is one of several purported diatremes of the Late Cretaceous Delitzsch Complex, which comprises carbonatites and ultramafic lamprophyres emplaced into a heterogeneous series of volcanic and sedimentary rocks of Precambrian to Early Permian age (Kr&amp;#252;ger et al., 2013; Seifert et al., 2000). The Late Cretaceous peneplain is covered with about one hundred meters of Tertiary soft rock. According to R&amp;#246;llig et al. (1990), the Delitzsch Complex developed in six stages: (i) hidden intrusion of a dolomite carbonatite (rauhaugite) that led to the formation of a fenite aureole; (ii) ultramafic and alkaline lamprophyre intrusion (aln&amp;#246;ite, aillikite, monchiquite); (iii) formation of beforsitic diatremes (intrusive breccias), including xenoliths of dolomite carbonatite and ultramafic lamprophyre; (iv) ultramafic and alkali lamprophyres (dykes within diatremes of 3&lt;sup&gt;rd&lt;/sup&gt;&amp;#160;stage); (v) formation of beforsite and (vi) alvikite dykes.&lt;/p&gt;&lt;p&gt;The Storkwitz carbonatite is mainly characterized by beforsitic breccias containing abundant angular xenoliths of metasediments form the complete underlying stratigraphic succession, metamorphic and igneous rocks, as well as rounded xenoliths of ultramafic lamprophyre, rauhaugite, fenite, and glimmerite, which suggest the existence of a deep-seated carbonatite pluton (Seifert et al., 2000). It is remarkable that the fenites exhibit a different degree of fenitization and show occurrence of phlogopite in the strongly fenitized samples. The matrix of the Storkwitz carbonatite is mainly composed of ankerite and calcite/siderite, which corresponds to ferro- or silico-carbonatites.&lt;/p&gt;&lt;p&gt;Detailed petrographical observations on extensive drill core material, new analyses and a reinterpretation of published data confirm the existence of compositional variation and zonation within the carbonatite body that reflect independent crystallization history and formation due to multiple magmatic events. The different generations of apatite and phlogopite from the early stage of the plutonic dolomite carbonatite through the late-stage beforsite dykes and fine-grained calcite carbonatite veins shed light on the crystallization history and magma development of carbonatites.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;References&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;Kr&amp;#252;ger, J.C., Romer, R.L., K&amp;#228;mpf, H., 2013. Late Cretaceous ultramafic lamprophyres and carbonatites from the Delitzsch Complex, Germany. Chemical Geology, 353, 140-150.&lt;/p&gt;&lt;p&gt;R&amp;#246;llig, G., Viehweg, M., Reuter, N., 1990. The ultramafic lamprophyres and carbonatites of Delitzsch/GDR. Zeitschrift f&amp;#252;r Angewandte Geologie, 36, 49-54.&lt;/p&gt;&lt;p&gt;Seifert, W., K&amp;#228;mpf, H., Wasternack, J., 2000. Compositional variation in apatite, phlogopite and other accessory minerals of the ultramafic Delitzsch complex, Germany: implication for cooling history of carbonatites. Lithos, 53, 81-100.&lt;/p&gt;

Jadeite–K-feldspar rocks and jadeitites from northwest Turkey

1997 ◽  
Vol 61 (409) ◽  
pp. 835-843 ◽  
Author(s):  
Aral I. Okay
Keyword(s):  
Grain Size ◽  
Debris Flows ◽  
Bulk Rock ◽  
Rock Composition ◽  
Bulk Rock Composition ◽  
Fine Grained ◽  
Fine Grain ◽  
The Matrix ◽  
Mineral Pair

AbstractBlueschist-facies rocks with jadeite-K-feldspar-lawsonite paragenesis occur as exotic blocks in Miocene debris flows in the blueschist belt of northwest Turkey. The jadeite-K-feldspar rocks have a very fine grain size and although recrystallized locally retain a relict porphyritic volcanic texture. The former nepheline microphenocrysts, recognized from their characteristic shapes, are pseudomorphed by jadeite and K-feldspar, while the relict magmatic aegirine has rims of jadeite. The matrix of the rock consists of very fine-grained aggregates of jadeite, K-feldspar and lawsonite. In some blocks, jadeite makes up >60% of the mode. Jadeite, K-feldspar and lawsonite in the blocks are essentially pure end-member in composition. P-T estimates for these rocks are 8 ± 2 kbar and 300 ± 50°C. The preserved volcanic texture, relict aegirine and the bulk rock composition indicate that these rocks represent metamorphosed phonolites. The paragenesis in these rocks shows that jadeite-K-feldspar is a stable mineral pair in blueschist-facies P-T conditions.

Shock brecciation around the Kidd Creek deposit, Abitibi belt, Canada

2008 ◽  
Vol 45 (8) ◽  
pp. 871-878
Author(s):  
I. K. Pitcairn ◽  
N. T. Arndt
Keyword(s):  
Volcanic Rocks ◽  
Massive Sulfide ◽  
Chemical Compositions ◽  
Fine Grained ◽  
Volcanic Processes ◽  
The Matrix ◽  
Major Fault ◽  
Heavy Rare Earth Elements ◽  
Felsic Volcanic

The Kidd–Munro assemblage, Abitibi belt, Canada, is an ultramafic–mafic–felsic volcanic sequence that contains the giant Kidd Creek volcanic-hosted massive sulfide (VMS) deposit. The Kidd basin, 1.6 km northeast of the deposit, contains pervasively brecciated pillowed and massive basalts. The breccia is distinctly different from most breccias in volcanic rocks, which form through volcanic processes or during later deformation or alteration. The Kidd Creek breccia occurs pervasively through otherwise undeformed pillow interiors and margins, and also in localized corridors of particularly intense brecciation. Clasts are angular, up to 4 cm wide, hosted in a very fine-grained matrix, and commonly show jig-saw fit texture. The chemical compositions of the breccia fragments and matrix are generally similar, although the matrix is slightly enriched in high field-strength elements (HFSE) and heavy rare-earth elements (HREE) and depleted in some mobile elements, such as Rb and Ba. The breccia contains altered basaltic clasts and fragments of in-filled amygdales and is crosscut by late-stage quartz–carbonate–sulfide veins. The observations imply that the breccia was formed in-situ, with minimal transport of material, and developed after solidification of the volcanic rocks. In-situ breccias, such as these, are known to form proximal to major fault zones, but no such structure occurs in the vicinity of the Kidd Basin. We suggest the brecciation was caused by the propagation of shock waves from explosive volcanic eruption, perhaps related to the emplacement of felsic volcanic rocks observed in the Kidd Creek Mine. The breccia was subject to enhanced hydrothermal fluid flow, perhaps linked to the formation of the ore deposit.

scholarly journals Optimizing fitness-for-use of differentially private linear queries

2021 ◽  
Vol 14 (10) ◽  
pp. 1730-1742
Author(s):  
Yingtai Xiao ◽  
Zeyu Ding ◽  
Yuxin Wang ◽  
Danfeng Zhang ◽  
Daniel Kifer
Keyword(s):  
Gaussian Noise ◽  
Differential Privacy ◽  
Covariance Structure ◽  
Fine Grained ◽  
Private Data ◽  
Data Release ◽  
The Matrix ◽  
The Cost ◽  
Matrix Mechanism ◽  
Accuracy Constraints

In practice, differentially private data releases are designed to support a variety of applications. A data release is fit for use if it meets target accuracy requirements for each application. In this paper, we consider the problem of answering linear queries under differential privacy subject to per-query accuracy constraints. Existing practical frameworks like the matrix mechanism do not provide such fine-grained control (they optimize total error, which allows some query answers to be more accurate than necessary, at the expense of other queries that become no longer useful). Thus, we design a fitness-for-use strategy that adds privacy-preserving Gaussian noise to query answers. The covariance structure of the noise is optimized to meet the fine-grained accuracy requirements while minimizing the cost to privacy.

scholarly journals Lithology of the Upper Jurassic-Lower Cretaceous deposits of the eastern part of the Myrgovaam and Rauchua depressions, Western Chukotka

2020 ◽  
Vol 65 (4) ◽  
Author(s):  
Elena V. Vatrushkina ◽  
◽  
Marianna I. Tuchkova ◽  
Keyword(s):  
Lower Cretaceous ◽  
Upper Jurassic ◽  
Coarse Grained ◽  
Fine Grained ◽  
Tectonic Environment ◽  
The Matrix ◽  
Siliciclastic Rocks ◽  
Facies Variation ◽  
Felsic Volcanic ◽  
Cretaceous Deposits

Upper Jurassic-Lower Cretaceous deposits were formed on the South-Western margin of the Chukotka terrane in active tectonic environment. Their stratigraphic units characterized by sedimentary structures and lithology similarities, facies variation and scarcity of reliable fauna findings. Detailed lithological studies are necessary due to the absence of a unified approach to the stratigraphic division of deposits. The paper presents petrographic, geochemical, and isotope-geochemical characteristics of Upper Jurassic-Lower Cretaceous rocks. The stages of changing the sedimentation conditions and sources, which determined the differences in sedimentological features and the composition of the studied strata, are reconstructed. The Oxford-Kimmeridgian section is composed of sandy debris flow deposits with an arcosic composition of psammitic differences. Among their sources, ancient granitoids dominated, while siliciclastic rocks, volcanites and metamorphic complexes were secondary. Volgian-valanginian interval is characterized by the accumulation of sediments in various parts of the submarine fan. In Volgian sequences fine -, medium - and coarse-grained turbidites with lenses of small-pebble conglomerates are identified. A large number of simultaneous pyroclastic material in the Volgian deposits indicates the synchronous volcanic activity. In the Volgian period, the province was dominated by volcanites, mainly of the basaltic and andesitic composition, siliciclastic rocks were present in smaller amount. The Berriasin section is composed of fine-grained turbidites with single horizons of medium-grained turbidites and gravelitic lenses, as well as slope deposits in the form of rhythmically interbedded sandstones and mudstones with slump structures. Sandstones have greywacke composition and contain an admixture of ash material in the matrix. The main sources for Berriasian deposits were siliciclastic rocks and felsic volcanic complexes. The Valanginian section is represented by fine and medium-grained turbidites with horizons of amalgamated sandstones. Sandstones are classified as arkoses by the ratio of rock-forming components. The dominant source in the Valanginian time was ancient granitoids, while siliciclastic rocks and volcanites were secondary.

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