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1.
Sci Rep ; 12(1): 11376, 2022 07 05.
Artículo en Inglés | MEDLINE | ID: mdl-35790847

RESUMEN

To fully assess the resilience and recovery of life in response to the Cretaceous-Paleogene (K-Pg) boundary mass extinction ~ 66 million years ago, it is paramount to understand biodiversity prior to the Chicxulub impact event. The peak ring of the Chicxulub impact structure offshore the Yucatán Peninsula (México) was recently drilled and extracted a ~ 100 m thick impact-generated, melt-bearing, polymict breccia (crater suevite), which preserved carbonate clasts with common biogenic structures. We pieced this information to reproduce for the first time the macrobenthic tracemaker community and marine paleoenvironment prior to a large impact event at the crater area by combining paleoichnology with micropaleontology. A variable macrobenthic tracemaker community was present prior to the impact (Cenomanian-Maastrichtian), which included soft bodied organisms such as annelids, crustaceans and bivalves, mainly colonizing softgrounds in marine oxygenated, nutrient rich, conditions. Trace fossil assemblage from these upper Cretaceous core lithologies, with dominant Planolites and frequent Chondrites, corresponds well with that in the overlying post-impact Paleogene sediments. This reveals that the K-Pg impact event had no significant effects (i.e., extinction) on the composition of the macroinvertebrate tracemaker community in the Chicxulub region.


Asunto(s)
Extinción Biológica , Meteoroides , Biodiversidad , Fósiles , México
2.
Astrobiology ; 22(4): 439-451, 2022 04.
Artículo en Inglés | MEDLINE | ID: mdl-35427147

RESUMEN

Phenylalanine (Phe) is an amino acid that has been identified in carbonaceous meteorites; its formation mechanism in space is unknown, and its radioresistance has been the subject of investigation. This work aims at studying, in the laboratory, the Phe radiolysis by cosmic analogues. The Phe destruction rate, at 300 K, is measured for H, He, and N ion beam irradiation in the 0.5 to 2 kinetic MeV range. Fourier transform infrared (FTIR) spectroscopy was employed to monitor the molecular degradation as a function of fluence. The Phe apparent destruction cross-section, σapd, which includes radiolysis and sputtering processes, is determined to be proportional to the electronic stopping power, Se. The measured parameter D0 = 14.3 ± 2.2 eV/molec in the relationship, and σdap = Se/D0 is interpreted as the mean absorbed dose necessary to dissociate or eject a Phe molecule. The Phe half-life in the interstellar medium is predicted to be about 10 million years, H+ ions the main destructive cosmic ray constituent.


Asunto(s)
Meteoroides , Fenilalanina , Iones , Cinética , Espectroscopía Infrarroja por Transformada de Fourier
3.
Nature ; 600(7889): 462-467, 2021 12.
Artículo en Inglés | MEDLINE | ID: mdl-34912082

RESUMEN

Establishing when, and from where, carbon, nitrogen and water were delivered to Earth is a fundamental objective in understanding the origin of habitable planets such as Earth. Yet, volatile delivery to Earth remains controversial1-5. Krypton isotopes provide insights on volatile delivery owing to their substantial isotopic variations among sources6-10, although pervasive atmospheric contamination has hampered analytical efforts. Here we present the full suite of krypton isotopes from the deep mantle of the Galápagos and Iceland plumes, which have the most primitive helium, neon and tungsten isotopic compositions11-16. Except for 86Kr, the krypton isotopic compositions are similar to a mixture of chondritic and atmospheric krypton. These results suggest early accretion of carbonaceous material by proto-Earth and rule out any combination of hydrodynamic loss with outgassing of the deep or shallow mantle to explain atmospheric noble gases. Unexpectedly, the deep-mantle sources have a deficit in the neutron-rich 86Kr relative to the average composition of carbonaceous meteorites, which suggests a nucleosynthetic anomaly. Although the relative depletion of neutron-rich isotopes on Earth compared with carbonaceous meteorites has been documented for a range of refractory elements1,17,18, our observations suggest such a depletion for a volatile element. This finding indicates that accretion of volatile and refractory elements occurred simultaneously, with krypton recording concomitant accretion of non-solar volatiles from more than one type of material, possibly including outer Solar System planetesimals.


Asunto(s)
Carbono/análisis , Planeta Tierra , Evolución Planetaria , Sedimentos Geológicos/química , Criptón/análisis , Atmósfera/química , Ecuador , Evolución Química , Helio/análisis , Islandia , Isótopos/análisis , Meteoroides , Neón/análisis , Neutrones , Nitrógeno/análisis , Tungsteno/análisis , Xenón/análisis
4.
Sci Prog ; 104(2): 368504211019859, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34019459

RESUMEN

The new Cuban chondrite, Viñales, fell on February first, 2019 at Pinar del Rio, northwest of Cuba (22°37'10″N, 83°44'34″W). A total of about 50-100 kg of the meteorite were collected and the masses of individual samples are in a range 2-1100 g. Two polished thin sections were studied by optical microscope, Raman spectroscopy and electron microprobe analysis in this study. The meteorite mainly consists of olivine (Fa24.6), low-Ca pyroxene (Fs20.5), and troilite and Fe-Ni metal, with minor amounts of feldspar (Ab82.4-84.7). Three poorly metamorphosed porphyritic olivine-pyroxene and barred olivine chondrules are observed. The homogeneous chemical compositions and petrographic textures indicate that Viñales is a L6 chondrite. The Viñales has fresh black fusion crust with layered structure, indicating it experienced a high temperature of ∼1650°C during atmospheric entry. Black shock melt veins with width of 100-600 µm are pervasive in the Viñales and olivine, bronzite, and metal phases are dominate minerals of the shock melt vein. The shock features of major silicate minerals suggest a shock stage S3, partly S4, and the shock pressure could be >10 GPa.


Asunto(s)
Meteoroides , Cuba , Minerales/análisis , Minerales/química , Espectrometría Raman
5.
PLoS One ; 14(7): e0218750, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31260466

RESUMEN

This study presents multiwall and bamboo-like carbon nanotubes found in samples from the Allende carbonaceous chondrite using high-resolution transmission electron microscopy (HRTEM). A highly disordered lattice observed in this material suggests the presence of chiral domains in it. Our results also show amorphous and poorly-graphitized carbon, nanodiamonds, and onion-like fullerenes. The presence of multiwall and bamboo-like carbon nanotubes have important implications for hypotheses that explain how a probable source of asymmetry in carbonaceous chondrites might have contributed to the enantiomeric excess in soluble organics under extraterrestrial scenarios. This is the first study proving the existence of carbon nanotubes in carbonaceous chondrites.


Asunto(s)
Medio Ambiente Extraterrestre , Meteoroides , Nanodiamantes/ultraestructura , Nanotubos de Carbono/ultraestructura , Planeta Tierra , Fulerenos/química , México , Microscopía Electrónica de Transmisión , Nanodiamantes/química , Nanotubos de Carbono/química
7.
Electrophoresis ; 39(22): 2898-2905, 2018 11.
Artículo en Inglés | MEDLINE | ID: mdl-30229957

RESUMEN

The importance of microorganisms and biotechnology in space exploration and future planets colonization has been discussed in the literature. Meteorites are interesting samples to study microbe-mineral interaction focused on space exploration. The chemolithotropic bacterium Acidithiobacillus ferrooxidans has been used as model to understand the iron and sulfur oxidation. In this work, capillary electrophoresis with capacitively coupled contactless conductivity detection and UV detection was used to monitor bacterial growth in a meteorite simulant by measuring the conversion of Fe2+ into Fe+3 . The effect of Co2+ and Ni2+ (metals also found in meteorites) on the bacterial growth was also evaluated. The presented method allowed the analyses of all metals in a single run (less than 8 min). The background electrolyte was composted of 10 mmol/L α-hydroxyisobutyric acid/Histidine. For comparison purpose, the samples were also analyzed by UV-Vis spectrophotometry. The Fe2+ conversion into Fe3+ by A. ferrooxidans was observed up to 36 h with the growth rate constant of 0.19/h and 0.21/h in Tuovinen and Kelly (T&K) and in meteorite simulant media, respectively. The developed method presents favorable prospect to monitor the growth of other chemolithotropic microorganisms for biotechnology applications.


Asunto(s)
Acidithiobacillus/metabolismo , Electroforesis Capilar/métodos , Meteoroides , Acidithiobacillus/química , Crecimiento Quimioautotrófico , Hierro/análisis , Hierro/metabolismo , Oxidación-Reducción , Reproducibilidad de los Resultados , Espectrofotometría Ultravioleta , Sulfuros/análisis , Sulfuros/metabolismo
8.
Homeopatia Méx ; 82(686): 11-19, sept-oct. 2013.
Artículo en Español | HomeoIndex - Homeopatia | ID: hom-11086

RESUMEN

A lo largo de 155 años, médicos homeópatas e instituciones académicas han promovido el estudio y la configuración de las patogenesias de diversos remedios mexicanos. Este trabajo relata la historia de 54 de ellas y señala datos específicos acerca de su acción terapéutica. Es importante resaltar las investigaciones en torno a Meteorita campo cielo (es la primera vez en la historia que se experimenta con un meteorito), y Cinis popo (ceniza del volcán Popocatépetl). (AU)


Over 155 years, homeopaths and academic institutions have promoted the study and configuration of several mexican remedies pathogenesis . This work tells the story of 54 of them and points out specific facts about its therapeutic action. Importantly, the research on Campo cielo meteorite (the first time in history that is experienced with a meteorite), and Cinis popo (Popocatepetl volcano ash). (AU)


Asunto(s)
Medicamento Homeopático , Homeopatía/historia , Materia Medica/historia , México , Meteoroides , Erupciones Volcánicas
9.
Homeopatia Méx ; 82(686): 11-19, sept.-oct. 2013.
Artículo en Español | LILACS | ID: lil-762177

RESUMEN

A lo largo de 155 años, médicos homeópatas e instituciones académicas han promovido el estudio y la configuración de las patogenesias de diversos remedios mexicanos. Este trabajo relata la historia de 54 de ellas y señala datos específicos acerca de su acción terapéutica. Es importante resaltar las investigaciones en torno a Meteorita campo cielo (es la primera vez en la historia que se experimenta con un meteorito), y Cinis popo (ceniza del volcán Popocatépetl).


Over 155 years, homeopaths and academic institutions have promoted the study and configuration of several mexican remedies pathogenesis . This work tells the story of 54 of them and points out specific facts about its therapeutic action. Importantly, the research on Campo cielo meteorite (the first time in history that is experienced with a meteorite), and Cinis popo (Popocatepetl volcano ash).


Asunto(s)
Medicamento Homeopático , Homeopatía/historia , Materia Medica/historia , Farmacopeas Homeopáticas como Asunto , Meteoroides , México , Erupciones Volcánicas
11.
Proc Natl Acad Sci U S A ; 109(19): 7208-12, 2012 May 08.
Artículo en Inglés | MEDLINE | ID: mdl-22529347

RESUMEN

The Younger Dryas impact hypothesis contends that an extraterrestrial object exploded over North America at 12.9 ka, initiating the Younger Dryas cold event, the extinction of many North American megafauna, and the demise of the Clovis archeological culture. Although the exact nature and location of the proposed impact or explosion remain unclear, alleged evidence for the fallout comes from multiple sites across North America and a site in Belgium. At 6 of the 10 original sites (excluding the Carolina Bays), elevated concentrations of various "impact markers" were found in association with black mats that date to the onset of the Younger Dryas. Black mats are common features in paleowetland deposits and typically represent shallow marsh environments. In this study, we investigated black mats ranging in age from approximately 6 to more than 40 ka in the southwestern United States and the Atacama Desert of northern Chile. At 10 of 13 sites, we found elevated concentrations of iridium in bulk and magnetic sediments, magnetic spherules, and/or titanomagnetite grains within or at the base of black mats, regardless of their age or location, suggesting that elevated concentrations of these markers arise from processes common to wetland systems, and not a catastrophic extraterrestrial impact event.


Asunto(s)
Frío , Clima Desértico , Sedimentos Geológicos/análisis , Humedales , Animales , Bélgica , Radioisótopos de Carbono/análisis , Chile , Planeta Tierra , Ecosistema , Extinción Biológica , Geología , Humanos , Iridio/análisis , Imanes , Meteoroides , Modelos Teóricos , Suelo/análisis , Sudoeste de Estados Unidos , Factores de Tiempo
12.
Proc Natl Acad Sci U S A ; 109(13): E738-47, 2012 Mar 27.
Artículo en Inglés | MEDLINE | ID: mdl-22392980

RESUMEN

We report the discovery in Lake Cuitzeo in central Mexico of a black, carbon-rich, lacustrine layer, containing nanodiamonds, microspherules, and other unusual materials that date to the early Younger Dryas and are interpreted to result from an extraterrestrial impact. These proxies were found in a 27-m-long core as part of an interdisciplinary effort to extract a paleoclimate record back through the previous interglacial. Our attention focused early on an anomalous, 10-cm-thick, carbon-rich layer at a depth of 2.8 m that dates to 12.9 ka and coincides with a suite of anomalous coeval environmental and biotic changes independently recognized in other regional lake sequences. Collectively, these changes have produced the most distinctive boundary layer in the late Quaternary record. This layer contains a diverse, abundant assemblage of impact-related markers, including nanodiamonds, carbon spherules, and magnetic spherules with rapid melting/quenching textures, all reaching synchronous peaks immediately beneath a layer containing the largest peak of charcoal in the core. Analyses by multiple methods demonstrate the presence of three allotropes of nanodiamond: n-diamond, i-carbon, and hexagonal nanodiamond (lonsdaleite), in order of estimated relative abundance. This nanodiamond-rich layer is consistent with the Younger Dryas boundary layer found at numerous sites across North America, Greenland, and Western Europe. We have examined multiple hypotheses to account for these observations and find the evidence cannot be explained by any known terrestrial mechanism. It is, however, consistent with the Younger Dryas boundary impact hypothesis postulating a major extraterrestrial impact involving multiple airburst(s) and and/or ground impact(s) at 12.9 ka.


Asunto(s)
Sedimentos Geológicos/química , Geología , Meteoroides , Modelos Teóricos , Carbono/análisis , Carbón Orgánico/análisis , Europa (Continente) , Groenlandia , Historia Antigua , Lagos/química , Magnetismo , México , Microscopía Electrónica de Rastreo , Nanodiamantes/análisis , América del Norte , Polen/fisiología , Hollín/análisis , Espectroscopía de Pérdida de Energía de Electrones , Temperatura , Factores de Tiempo , Difracción de Rayos X
13.
Artículo en Inglés | MEDLINE | ID: mdl-21930423

RESUMEN

The Raman (RMP), infrared (IR) and XRD analysis have been applied to the examination of mineralogical composition of El Pozo meteorite (an ordinary chondrite L5 type; village Valle of Allende, founded in State of Chihuahua, Mexico: 26°56'N and 105°24'W, 1998). RMP measurements in the range of 100-3500 cm(-1) revealed principal characteristic bands of the major minerals: olivine, two polymorph modifications of pyroxene (OPx and CPx) and plagioclase. Some bands of the minor minerals (hematite and goethite) were also identified. All these minerals were clearly distinguished using IR and XRD techniques. XRD technique has shown the presence of some metallic phases such as kamacite and taenite as well as troilite and chromite. These minerals do not have characteristic Raman spectra because Fe-Ni metals have no active modes for Raman spectroscopy and troilite is a weak Raman scatterer. Raman mapping microspectroscopy was a key part in the investigation of El Pozo meteorite's spatial distribution of the main minerals because these samples are structurally and chemically complex and heterogeneous. The mineral mapping by Raman spectroscopy has provided information for a certain spatial region on which a spatial distribution coexists of the three typical mineral assemblages: olivine; olivine+orthopyroxene; and orthopyroxene.


Asunto(s)
Meteoroides , Minerales/química , Compuestos Férricos/análisis , Compuestos de Hierro/análisis , Compuestos de Magnesio/análisis , México , Minerales/análisis , Silicatos/análisis , Espectrofotometría Infrarroja , Espectrometría Raman , Difracción de Rayos X
14.
Sci Am ; 292(5): 28-9, 2005 May.
Artículo en Inglés | MEDLINE | ID: mdl-15882015
16.
Astrobiology ; 3(1): 99-118, 2003.
Artículo en Inglés | MEDLINE | ID: mdl-12804368

RESUMEN

We use one-dimensional (1D) atmospheric models coupled to a sulfate aerosol model to investigate climate forcing and short-term response to stratospheric sulfate aerosols produced by the reaction of S-bearing gases and water vapor released in the Chicxulub impact event. A 1D radiation model is used to assess the climate forcing due to the impact-related loading of S-bearing gases. The model suggests that a climate forcing 100 times larger than that from the Pinatubo volcanic eruption is associated with the Chicxulub impact event for at least 2 years after the impact. In particular, we find a saturation effect in the forcing, that is, there is no significant difference in the maximum forcing between the highest (approximately 300 Gt) and lowest (approximately 30 Gt) estimated stratospheric S-loading from the Chicxulub impact. However, higher S-loads increase the overall duration of the forcing by several months. We use a single column model for a preliminary investigation of the short-term climate response to the impact-related production of sulfate aerosols (the lack of horizontal feedbacks limits the usefulness of the single column model to the first few days after the impact). Compared with the present steady-state climate, the introduction of large amounts of sulfate aerosols in the stratosphere results in a significant cooling of the Earth's surface. A long-term climate response can only be investigated with the use of a three-dimensional atmospheric model, which allows for the atmospheric circulation to adjust to the perturbation. Overall, although the climate perturbation to the forcing appears to be relatively large, the geologic record shows no sign of a significant long-term climatic shift across the K/T boundary, which is indicative of a fast post-impact climatic recovery.


Asunto(s)
Clima , Sedimentos Geológicos/química , Planeta Tierra , Ambiente , Historia Antigua , Meteoroides , México , Modelos Teóricos
17.
Adv Space Res ; 27(2): 231-6, 2001.
Artículo en Inglés | MEDLINE | ID: mdl-11605637

RESUMEN

The hypothesis on exogenous origin of organic matter on the early Earth is strongly supported by the detection of a large variety of organic compounds (including amino acids and nucleobases) in carbonaceous chondrites. Whether such complex species can be successively delivered by other space bodies (comets, asteroids and interplanetary dust particles) is unclear and depends primarily on capability of the biomolecules to survive high temperatures during atmospheric deceleration and impacts to the terrestrial surface. Recent simulation experiments on amino acid and nucleic acid base pyrolysis under oxygen-free atmosphere demonstrated that simple representatives of these (considered thermally unstable) compounds can survive at 1-10% level a rapid heating at 500-600 degrees C. In the present work, we report on new data on the pyrolysis of amino acids and their homopolymers and discuss implications of their thermal behavior for extraterrestrial delivery.


Asunto(s)
Aminoácidos/química , Calor , Piperazinas/síntesis química , Ácido Pirrolidona Carboxílico/síntesis química , Medio Ambiente Extraterrestre , Geles/química , Ácido Glutámico/química , Leucina/química , Meteoroides , Fenilalanina/química , Prolina/química , Gel de Sílice , Dióxido de Silicio/química , Valina/química , beta-Alanina/química
20.
Adv Space Res ; 24(4): 505-14, 1999.
Artículo en Inglés | MEDLINE | ID: mdl-11543338

RESUMEN

The idea of extraterrestrial delivery of organic matter to the early Earth is especially attractive at present and is strongly supported by the detection of a large variety of organic compounds, including amino acids and nucleobases, in carbonaceous chondrites. Whether these compounds can be delivered by other space bodies is unclear and depends primarily on capability of the biomolecules to survive high temperatures during atmospheric deceleration and impacts to the terrestrial surface. In the present study we estimated survivability of simple amino acids (alpha-aminoisobutyric acid, L-alanine, L-valine and L-leucine), purines (adenine and guanine) and pyrimidines (uracil and cytosine) under rapid heating to temperatures of 400 to 1000 degrees C under N2 or CO2 atmosphere. We have found that most of the compounds studied cannot survive the temperatures substantially higher than 700 degrees C; however at 500-600 degrees C, the recovery can be at a per cent level (or even 10%-level for adenine, uracil, alanine, and valine). Implications of the data for extraterrestrial delivery of the biomolecules are discussed.


Asunto(s)
Aminoácidos/química , Medio Ambiente Extraterrestre , Calor , Meteoroides , Adenina/química , Polvo Cósmico , Citosina/química , Planeta Tierra , Evolución Química , Guanina/química , Origen de la Vida , Oxidación-Reducción , Tamaño de la Partícula , Piperazinas/síntesis química , Uracilo/química
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