Types of rock, such as komatiite, which formed entirely or dominantly during restricted time periods in solar system history, are important indicators of how planetary bodies evolved in deep time. In ...this paper we characterize three different types of temporally-restricted anorthosites, and discuss their significance to the broad-scale evolution of planetary processes. Primordial anorthosites, which constitute the bulk of the lunar crust, were sampled during Apollo and Luna missions, and have subsequently been identified in our meteorite collections. They are characterized by very calcic plagioclase (An93–98), and all have magmatic crystallization ages >4.3Ga, suggesting that the earliest planetary crust-forming processes on the Moon, and possibly elsewhere, involved substantial, if not total melting. The “magma ocean” hypothesis, which has endured for nearly 50years, argues that the lunar anorthositic rocks represent global flotation cumulates of plagioclase, which crystallized after extensive precipitation and sinking of olivine and pyroxene. Another possibility, revitalized by critical filtering of age data, involves “serial magmatism”, whereby the lunar crust was constructed by younger, smaller, episodic magmatic events. On Earth, two distinct types of temporally-restricted anorthosites offer opportunities to understand the evolution of terrestrial geodynamics, tectonics and magmatic processes. Archean megacrystic anorthosites formed only between 3.73 and 2.49Ga as small bodies (<500km2) associated with the mafic magmatic assemblages of many greenstone belts. They are typified by accumulations of equidimensional, almost spherical megacrysts (1–30cm across) of calcic plagioclase (An61–94, avg. An80) in a mafic groundmass of broadly basaltic composition, and probably formed in shallow magma chambers. The unusually calcic plagioclase compositions may reflect crystallization from hydrous and/or Ca-rich basaltic parents that were fractionated derivatives of more primitive magmas, possibly even komatiites. Isotopic and geochemical data for many Archean anorthosite complexes indicate little to no evidence for contamination by silicic continental crust, suggesting magma formation in oceanic environments, most likely by subduction in oceanic arcs. Their temporal restriction might be explicable in terms of a hotter or wetter Archean mantle, especially if a genetic connection to komatiites can be demonstrated. Alternatively, higher Archean heat flow may have influenced oceanic crustal thickness, subduction rate, sites of magma generation and/or melt composition, producing favorable conditions for the generation of calcic megacrystic anorthosites. Proterozoic massif-type anorthosites are distinctly different from other anorthosite types, and occur as small plutons (1–10km2), to large (up to 18,000km2) composite batholiths, that are temporally restricted to a ~2000m.y. period between ~0.5 and ~2.6Ga. The rocks are dominated by lath-shaped, intermediate plagioclase (An30–70, avg. An53), with lesser pyroxenes and/or olivine. There is extensive evidence from petrology, geochemistry and isotope data for variable contamination with continental crust, and the most plausible physical model involves deep-crustal ponding of basaltic magmas, crystallization and sinking of mafic silicates, and eventual flotation of buoyant plagioclase. Massifs were constructed by the coalescence of plagioclase-rich mushes, which ascended to mid-crustal emplacement sites. The basaltic parent melts or magmas for massif-type anorthosites were mantle-derived; alternative models involving melting of crustal sources, mafic or otherwise, cannot be supported. Collective features most readily support an Andean-type continental arc setting, and careful geochronology is beginning to suggest that magmatism in individual massifs may have occurred over long time-scales of up to 100m.y. The onset of massif-type anorthosite formation at ~2.6Ga probably reflects global secular cooling of the Earth, resulting in increased lithospheric strength and crustal thickness, which promoted Moho-depth ponding and slow crystallization of basaltic magmas in continental arc environments. The apparent disappearance of anorthosite massifs at ~0.5Ga may also relate to global secular cooling that changed the thermal structure of subduction zones, and promoted the onset of high and ultra-high pressure metamorphism.
En el presente trabajo se realizará un estudio sobre la explotación de los recursos naturales que se encuentran en la Luna, principalmente el regolito o polvo lunar enfocado a determinar si la ...regulación en el Tratado del Espacio y en el Acuerdo Luna permite la explotación del mismo, así como los problemas jurídicos que se pueden plantear respecto a la titularidad de ese bien, y su comercialización. Se analizará también las consecuencias futuras que pueden desencadenar la explotación de los recursos naturales como consecuencia de la evolución de las misiones espaciales con destino a la Luna.
The Terra-LUNA crash in May 2022 was triggered by the depeg of the ecosystem’s stablecoin UST. It led to the unprecedented demise of a blockchain ecosystem and cost investors tens of billions of ...dollars. We examined the impact of the Terra-LUNA crash on the cryptocurrency market. Based on the hourly return and realized volatility from April 2022 to May 2022, we used the spillover index and effective transfer entropy to configure the interlinkage change between cryptocurrency markets. We conclude that the Terra-LUNA crash had a significant impact on the connectedness of the cryptocurrency market, investor attention, and market sentiment.
•This paper is the first study of Terra-LUNA crash using the spillover index and transfer entropy.•We used the hourly prices, Google Trends index, and StockTwits to analyze the crash.•We confirmed that the Terra-LUNA crash had a significant impact on the the overall cryptocurrency market.
INTRODUCCIÓN: En muchas sociedades alrededor del mundo existe una creencia que relaciona el ciclolunar con la frecuencia de nacimientos, especialmente debido a la influencia de la luna llena. Aunque ...lamayoría de los estudios no encuentran relación entre las diferentes fases lunares y la frecuencia de partosespontáneos, sigue existiendo esta creencia incluso entre profesionales de la salud.OBJETIVO: Demostrar el aumento de porcentaje de nacimientos por partos espontáneos durante la lunallena comparado con las otras fases, describir el porcentaje de nacimientos en cada fase lunar, mencionarla distribución de nacimientos según sexo, mostrar la distribución de nacimientos según edad gestacional,conocer cantidad de trabajos de parto terminados en cesárea o en parto vaginal y registrar lascomplicaciones en cada fase lunar.MATERIAL Y MÉTODO: Estudio de cohorte, retrospectivo, observacional y analítico. La población estáconstituida por embarazadas que ingresen a nuestra Institución en trabajo de parto espontáneo. El tiempocomprendido es entre el 01/01/2021 hasta el 31/01/2022. Los datos se obtienen del Libro de parto delServicio de Tocoginecología de la Clínica. El análisis de datos se realiza mediante el cálculo de la media,mediana y cuartiles para las variables categóricas, utilizando el software R, versión x644.1.1 y el Test deChi2.RESULTADO: Entre enero del año 2021 a 2022, hay anotados un total 1003 nacimientos de partosdesencadenados en forma espontánea, incluyendo aquellos tanto a término como pretérmino. No sedemostró una diferencia estadística en la distribución de nacimientos por sexos entre las diferentes faseslunares (P < 0,8). Teniendo en cuenta las edades gestacionales, la mediana es de 39 semanas, la media de38,5 semanas, mínima, 22 semanas y la máxima, 41,4 semanas. Con respecto a la distribución de la cantidadde nacimientos con las diferentes fases lunares, obtuvimos que durante la fase de Luna Nueva el total es de275 (27,4%), en la fase Cuarto Creciente de 212 (21,1%), en Luna Llena de 264 (26,3%) y en CuartoMenguante de 252 (25,1%) (P< 0,3), no encontrándose diferencias estadísticas significativas entre lasvariables. No se encontró una relación estadística significativa entre las variables de cantidad denacimientos y las distintas fases lunares. Cuando analizamos las complicaciones y observaciones del trabajode parto presentadas, se obtuvo que la cantidad de las mismas fueron 176. Siendo la más frecuente la roturaprematura de membranas, con un total de 162 casos (92%), aunque no se objetiva una diferenciasignificativa entre la incidencia de las complicaciones en las diferentes fases lunares (P <0,5).CONCLUSIONES: A pesar de las numerosas investigaciones llevadas a cabo, el mito de las fases lunaresaún se encuentra extendido geográficamente, y continúa transmitiéndose a lo largo de las generaciones,formando parte del folclore de nuestra comunidad. En escasos trabajos de investigación en donde seestableció un aumento de la incidencia de nacimientos, no hubo consenso de que fase lunar es la másinfluyente.
Dentro de la literatura revisada, el análisis llevado a cabo por Gutziunaite y col. demostró mayortasa de nacimientos durante la fase de luna llena.Nuestros resultados no mostraron diferencias significativas con respecto a los nacimientos en las distintasfases lunares.Dentro de las limitaciones de este estudio, se incluyen los sesgos de selección y de información, ya que setrata de un estudio de tipo observacional. Por otro lado, no se analizaron resultados como abortosespontáneos y evacuaciones del segundo trimestre dentro de las complicaciones.
Measuring the spatial density of craters emplaced on geologic units is the primary method used for remotely estimating ages of solar system surfaces. The calibration for this method, which enables ...conversion of crater density to absolute age, comes from Apollo and Luna lunar samples for which absolute radiometric ages have been determined. Researchers throughout the 1970s worked to establish the lunar chronology system based on that calibration, correlating crater densities with absolute ages. However, no uniform crater study has been conducted on all calibration terrains, a limitation that was previously unaddressed until this study. The latest lunar images from the Lunar Reconnaissance Orbiter were used here to re-map the eleven main sampling sites and new crater counts of those surfaces were conducted. These show significant differences for many sites' crater counts, in many cases having more craters than previously identified. These results, calibrated to the radiometric ages, show a revised lunar crater chronology that changes previously established crater-based ages by up about 1 billion years: Surfaces younger than ∼3.6 Gyr and older than ∼3.9 Gyr under the classic chronology are younger in this system, and those in-between are older in this new system.
•New mapping and crater counts of Apollo and Luna chronology calibration sites.•Most sites have a higher density of ≥1-km-diameter craters than previous work.•Some ages dated via craters are up to 1.1 Gyr younger than previously thought.
The Luna 20 mission returned samples from the Hilly and Furrowed Terrain of the Moon that is associated with the impact event that formed the Crisium Basin. This event potentially excavated deep ...crustal and upper mantle lithologies. Spinel is commonly considered to be a mineralogical indicator of rocks of high‐pressure origin, and orbital data indicate the presence of spinel‐bearing lithologies exterior to the basin. We have examined 166 Luna 20 particles in the 250–500 μm size range and found 31 spinel‐bearing fragments. Of these 10 are igneous plutonic Mg‐suite rocks, most of which are troctolitic, and 16 are impact melt rocks. The other five are fused soil or devitrified glass fragments. The spinel‐bearing lithic fragments are plagioclase‐rich and do not have the high modal abundances of Mg‐Al spinel previously identified in the region through remote sensing analyses. The textures, compositions, and inferred crystallization sequences of the present magmatic spinel‐bearing samples are most consistent with a relatively shallow crustal (rather than a deep crustal) origin, with a petrogenesis involving assimilation of ferroan anorthosite crust by Mg‐rich, mantle‐derived magmas. Both relict and newly formed spinels are found in impact melt rocks and are also inferred to have formed at relatively low pressures. Thus, the presence of spinel is not an unambiguous indicator of mantle or deep crustal material. The insights gained from this study show that studies of a small, robotically collected sample can improve our understanding of regional lithologies and petrologic processes.
Plain Language Summary
Lunar rocks that contain spinel have long been thought to have formed at high pressures and have deep sources. A survey of lithic fragments in the Luna 20 regolith shows that spinel occurs in igneous and impact melt rocks with features more consistent with relatively rapid cooling than with slow cooling, and therefore relatively shallow depths of origin. The presence of spinel in a lunar rock is not an unambiguous indicator of mantle or deep crustal material.
Key Points
Spinel‐bearing rock fragments found in the Luna 20 regolith provide insights into the origin and distribution of lunar spinel‐bearing lithologies
Evidence for rapid cooling suggests these lithologies did not have deep sources and probably formed at relatively shallow depths
The Upper Cretaceous succession in northern South America is significant because the related rock deposits are among the most prolific oil sources in the region. Although several geological studies ...have focussed on this period, we still have poor knowledge of the exact deposition time of the lithostratigraphic units. In this study, we constructed a chronostratigraphic framework based on U–Pb ages and time-calibrated carbon isotopic events to constrain the chronostratigraphy of the Upper Cretaceous formations. The carbon isotope curve of the La Luna-1 core allowed us to identify several oceanic anoxic events also identified in the stratotypes of the Upper Cretaceous formations. The La Luna-1 also preserves a complete record of ash beds, from which zircons were extracted for U–Pb dating. The stratigraphic distribution of the ash beds indicates a crucial influence of volcanic activity during the Late Cretaceous. Sedimentological descriptions and mineralogical analysis were used to establish the primary lithological differences between the units. The Upper Cretaceous formations can be categorised as mixed rocks comprising variable percentages of carbonates, quartz and clay minerals. They also show silicification and, to a lesser extent, dolomitisation and recrystallisation. The Salada, Pujamana, and Galembo formations range in age between the Cenomanian and Coniacian, whereas the overlying La Renta Formation spans from the Santonian to at least the middle Campanian. The top of the La Renta Formation corresponds to a regional disconformity that contacted the middle Campanian with the Maastrichtian.
•The Cretaceous was characterized by high burial rates of carbon in the form of carbonates and organic carbon, much of the latter forming a significant proportion of the hydrocarbon source rocks in many sedimentary basins around the world, including South America.•The late Cretaceous of northern South America preserves a very complete record of the oceanic anoxic events (OAEs) that have been reported globally.•The late Cretaceous was characterized by the occurrence of an important volcanic activity.•The La Luna Formation was deposited between the Cenomanian and Santonian and their former members (Salada, Pujamana, and Galembo) should be elevated to the category of formations.
Twelve landing ellipses (15 × 30 km each) were previously selected during the preliminary science and safety assessment of details of the Russian Luna-Glob mission. In our work, we have conducted a ...photogeological and topographical study of the top three most desirable landing ellipses (ellipses 1, 4, and 6) and modelled the thickness of the lunar basin ejecta at these locations in order to characterize their safety conditions and possible sources of materials. For all three potential landing sites large (>0.3–0.5 m) boulders do not represent a significant threat to the mission. The major safety concerns are small but abundant craters whose walls are steeper than the technical constraint of 7°. We have collected the data on density, areal fraction, and the mean distance between the neighboring steep-wall craters, which allow us to rank the safety of terrains within each landing ellipse. A set of morphologically and topographically distinctive units make up the surface of the landing ellipses. The units form two groups, the hilly units and the flat plains. The hilly units within the ellipses 1 and 6 are among the safest terrains. The flat plains of ellipses 1 and 4 represent the most unsafe surfaces. The ejecta of the South Pole-Aitken basin (SPA) strongly dominate the Luna-Glob landing zone and constitute ∼95% (by volume) of materials than can be encountered and analyzed within the landing ellipses. For example, the hilly units in the ellipses 1 and 6 likely represent materials of the SPA ejecta. In the ellipse 4, the hilly unit corresponds to the ejecta of Moretus crater and may represent materials excavated from below the SPA ejecta blanket. However, the small area and configuration of the hilly unit in ellipse 1 and abundant small steep-wall craters on the hilly unit in ellipse 4 make them either a difficult or an unsafe target to land. The flat plains in ellipses 1 and 4 are the most unsafe terrains to land because of the abundant steep-wall craters on their surfaces. Materials ejected by the large craters Boguslawsky and Boussingault from the lower portions of the SPA ejecta blanket make up the majority of the hilly unit in the landing ellipse 6. This unit is among the safest terrains in all top three landing ellipses of the Luna-Glob mission.
•The sources of materials in the top-three (1, 4, 6) Luna-Glob landing sites were analyzed.•The ejecta of the SPA basin dominate the entire Luna Glob landing area.•Flat plains in ellipses 1 and 4 may represent materials ejected from below the SPA ejecta.•Flat plains in ellipses 1 and 4 are the most unsafe units to land.•Units in ellipse 6 may represent materials from the lower portions of the SPA ejecta.
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