A new mineral phase was discovered in the course of studies at the Institute of Geology of Ore Deposits, Petrography, Mineralogy, and Geochemistry (IGEM) of fine-grained fractions of the lunar ...regolith delivered to the Earth by the
Luna 16
,
Luna 20
, and
Luna 24
automatic stations. The grain of native niobium was identified in the regolith sample from the Mare Crisium. Presumably, this phase was formed during the fractioning process in a gas–plasma cloud under an impact event on the Moon.
Laser ionization mass spectrometry is one of the most promising methods for analysis of the elemental and isotopic composition of solids in space experiments: the required instruments are highly ...reliable and easy to operate, no sample preparation is needed, and the spatial resolution of this method is relatively high. In view of this, the LASMA-LR laser ionization mass spectrometer was included into the list of instruments for the future Luna-Glob (
Luna-25
) and Luna-Resurs-1 (
Luna-27
) missions, where it will be used to examine the elemental and isotopic composition of lunar regolith at the landing sites. The accuracy of LASMA-LR measurements depends to a considerable extent on the size of the statistical sample of the spectral dataset. This defines the temporal parameters of operation of the mass spectrometer in a space experiment. A series of spectra of enstatite (mineral found in lunar regolith) was measured, and the instrumental accuracy of measurements with spectral datasets of different sizes was estimated. It was demonstrated that an elemental analysis accuracy of 10% is achieved by processing a set of 300 spectra, which corresponds to ~4 h of continuous LASMA-LR operation. A measurement accuracy of 1% for isotopic distributions is achieved within the same 4-hour period only for isotopes with ratios no higher than 10 : 1, while the same accuracy for isotopes with higher ratios requires an unfeasibly long analysis time.
The paper's subject is fifteen copper alloy lamps of various types and sizes from the Roman Collection of the Archaeological Museum of Istria, mostly collected in the first half of the 20th century ...in Istria and on the island of Cres. The lamps were classified according to shape into six basic types and compared with other finds to gain insight into the chronological framework, workshop centers, and distribution routes. Figural depictions on lamps have been interpreted as mythological and cult significance. The available data on the circumstances of the findings were analyzed and compared with the other data, from which assumptions were made about the possible time and causes of the storage of copper alloy lamps in hoards. The possible value of the copper alloy lamps is estimated according to their weight.
We present two previously unreported hominin permanent teeth one right upper second molar (M2), one left lower second molar (m2) from Lunadong (“dong” = “cave”), Guangxi Zhuang Autonomous Region, ...China. The teeth are important because: 1) they were found in situ; 2) at least one (M2) can be confidently assigned to modern Homo sapiens, while the other (m2) is likely modern H. sapiens; and 3) the teeth can be securely dated between 126.9 ± 1.5 ka and 70.2 ± 1.4 ka, based on multiple MC-ICP-MS uranium-series dates of associated flowstones in clear stratigraphic context. The Lunadong modern H. sapiens teeth contribute to growing evidence (e.g., Callao Cave, Huanglongdong, Zhirendong) that modern and/or transitional humans were likely in eastern Asia between the crucial 120–50 ka time span, a period that some researchers have suggested no hominins were present in the region.
The landing sites of the landers of Apollo 11, 12, 14, 15, 16, and 17 as well as Luna 16, 20, and 23 spacecraft are all located within specific phase-ratio anomalies caused by the engine jets. The ...landing site identified as that of the Luna 24 spacecraft, however, was not located within its corresponding anomaly, leading Shkuratov et al. (2013) to suggest that this may be due to the misidentification of the Luna 23 and 24 spacecraft in the LROC images, since the Luna 23 landing was not successful. Dolgopolov et al. (2013) synthesized images of the Luna spacecraft as they might appear in the LROC images, using a model made by the Lavochkin Association. They found similarity of the spacecraft seen in the LROC images with the synthetic images corresponding to successful and unsuccessful missions and concluded that the original identification of the Luna 23 and 24 spacecraft in the images by Robinson et al. (2012) is likely correct. However, Dolgopolov et al. (2013) used only one illumination geometry for each landing site. As distinct from Dolgopolov et al. (2013) we make a similar analysis using a 3D computer spacecraft model using several different illuminations of the spacecraft and show that the orientations used by Dolgopolov are inconsistent with other LROC images, and it is impossible to make a reliable conclusion based on these analyses. We also show that geologic arguments presented by Dolgopolov et al. (2013) are ambiguous. Using Lucey et al.’s (1995) technique and multispectral images acquired with the Kaguya MI camera (resolution ~20m), we show that small areas around the landing sites of the probes have almost the same contents of FeO and TiO2, as well as fairly close maturity degree of the regolith.
•The anomalous phase-ratio image of the Luna 24 landing site suggests misidentification.•Analysis of Luna 23 and 24 computer models does not confirm the original identification.•We found noticeable inconsistencies with results by Dolgopolov et al. (2013).•Geological arguments and multispectral analyses also are ambiguous for identification.
Este trabajo abarcó el estudio sedimentológico, paleontológico y geoquímico de la Formación La Luna, en una localidad al oeste del Macizo de Santander (Matanza, Colombia). La sección corresponde a un ...corte de 42 metros, compuesto por una alternancia de mudstones y wackestones interestratificados, niveles de chert, fosforitas y bentonitas. El contenido fósil está conformado por restos de amonitas, inocerámidos, gasterópodos turritélidos, fragmentos de peces y foraminíferos planctónicos. La asociación fósil indica una edad de Coniaciano-Santoniano. Las características sedimentológicas, el tipo de fósiles encontrados y los análisis petrográficos/geoquímicos desarrollados en esta sección sugieren condiciones de depositación en plataforma externa y una baja oxigenación en los sedimentos de fondo. Las conclusiones de este trabajo coinciden con interpretaciones preexistentes de la región cuenca, sugiriendo relaciones litoestratigráficas con la sucesión sedimentaria del Valle Medio del Magdalena (parte superior del “Miembro Galembo”). Sin embargo, solo estudios estratigráficos detallados en esta parte del Macizo de Santander, permitirán entender su evolución geológica durante el Cretácico superior.
•DRFTIR parameters distinguish organic facies in kerogen from La Luna Fm.•DRFTIR parameters distinguish thermal maturity in kerogen from La Luna Fm.•DRFTIR parameters have been applied on marine type ...II kerogen for first time.•A new calculation of uncertainty of DRFTIR parameters has been proposed.•An aliphaticity DRFTIR parameter AII has been proposed for kerogen type II.
Twelve samples of marine type II kerogen from La Luna Formation (Maracaibo sub-Basin, Western Venezuelan Basin) have been characterized via diffuse reflectance – Fourier-transform – infrared spectroscopy (DRFTIR). The samples were selected from different regions in the sub-Basin and correspond to different maturity levels with subtle variations in organic facies. For the analysis, the kerogen samples were mixed with potassium bromide (KBr) at a 5% w/w concentration. Spectra were obtained using a Varian 640-IR spectrometer operating in Fourier Transform mode and coupled with an EasiDiff diffuse reflectance accessory. Each spectrum was generated within the 400–4000 cm−1 frequency interval, at 4 cm−1 resolution, after 52 scans. IR parameters known to distinguish organic facies, such as the A factor and the C factor, separated the kerogen from anoxic environment (samples from the Maraca Creek) versus the kerogen from suboxic/disoxic conditions (samples from La Molina and San Antonio). Organic facies indices by Chen et al. (1998) showed to be influenced by maturity effects. Higher thermal maturity of samples from La Molina creek was supported by increasing aromaticity (indices by Lis et al., 2005), as well as decreasing aliphaticity as expressed by a new parameter termed here in as AII. This parameter compares aromatic signals in the 700–900 cm−1 interval with the aliphatic bands centered at 2953, 2923, and 2856 cm−1. This is the first study that applies DRFTIR compositional parameters to characterize kerogen type II from marine carbonates.
Flow diversion has become a well-accepted option for the treatment of cerebral aneurysms. Given the significant treatment effect of flow diverters, numerous options have emerged since the initial ...Pipeline embolization device studies. In this review, the authors describe the available flow diverters, both endoluminal and intrasaccular, addressing nuances of device design and function and presenting data on complications and outcomes, where available. They also discuss possible future directions of flow diversion.
Rufino Tamayo Rebollar Vergara, Luis
Designio, Investigación en Diseño Gráfico y Estudios de la Imagen,
04/2021, Letnik:
3, Številka:
1
Journal Article
Recenzirano
Odprti dostop
El objetivo del presente artículo es analizar el mural Dualidad del pintor oaxaqueño Rufino Tamayo. La finalidad consiste en la elaboración de una ficha de obra que contenga la descripción de los ...elementos del mural; con base en fuentes historiográficas, el contexto histórico, social y cultural en que se creó y la técnica empleada por el artista.
Magnesium‐rich spinel assemblages occur in the two lunar vitric breccia meteorites—Dhofar (Dho) 1528 and Graves Nunataks (GRA) 06157. Dho 1528 contains up to ~0.7 mm cumulate Mg‐rich spinel crystals ...associated with Mg‐rich olivine, Mg‐ and Al‐rich pyroxene, plagioclase, and rare cordierite. Using thermodynamic calculations of these mineral assemblages, we constrain equilibration depths and discuss an origin of these lithologies in the upper mantle of the Moon. In contrast, small, 10 to 20 μm spinel phenocryst assemblages in glassy melt rock clasts in Dho 1528 and GRA 06157 formed from the impact melting of Mg‐rich rocks. Some of these spinel phenocrysts match compositional constraints for spinel associated with “pink spinel anorthosites” inferred from remote sensing data. However, such spinel phenocrysts in meteorites and Apollo samples are typically associated with significant amounts of olivine ± pyroxene that exceed the compositional constraints for pink spinel anorthosites. We conclude that the remotely sensed “pink spinel anorthosites” have not been observed in the collections of lunar rocks. Moreover, we discuss impact‐excavation scenarios for the spinel‐bearing assemblages in Dhofar 1528 and compare the bulk rock composition of Dho 1528 to strikingly similar compositions of Luna 20 samples that contain ejecta from the Crisium impact basin.
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