Academic literature on the topic 'Meteorite lead content'
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Journal articles on the topic "Meteorite lead content"
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TOULKERIDIS, Theofilos, Richard Caleb ECHEGARAY-AVEIGA, and Karen Paola MARTINEZ-MALDONADO. "SHOCK METAMORPHISM IN VOLCANIC ROCK DUE TO THE IMPACT OF THE MIGUIR-CAJAS METEORITE IN 1995 AND ITS IMPORTANCE FOR ECUADOR." GeoJournal of Tourism and Geosites 35, no. 2 (June 30, 2021): 315–21. http://dx.doi.org/10.30892/gtg.35208-654.
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In the past of the earth several asteroids and meteoroids have been impacted, but most of these collisions have been eroded and today there are only sometimes direct and indirect indications, such as massive extinctions of species in the form of fossils, layers with content of extraterrestrial material among others. Based on our recent reconnaissance in the field in 2017, we have been able to identify a new impact of a meteorite on volcanic rock of the Miocene Tarqui Formation in central Ecuador. We were able to reveal and reconstruct the corresponding trajectory as well as its impact day being in 1995. Based on known impacts in South America, this is the very first to have been impacted on rocks, which would lead to a clear shock metamorphism. This discovery of the impact on a rock may soon be a major tourist attraction of the country due to its accessibility and importance for being unique in Ecuador and on the continent.
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Bisceglia, E., G. Micca Longo, and S. Longo. "Thermal decomposition rate of MgCO3as an inorganic astrobiological matrix in meteorites." International Journal of Astrobiology 16, no. 2 (April 13, 2016): 130–36. http://dx.doi.org/10.1017/s1473550416000070.
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AbstractCarbonate minerals, likely of hydrothermal origins and included into orthopyroxenite, have been extensively studied in the ALH84001 meteorite. In this meteorite, nanocrystals comparable with those produced by magnetotactic bacteria have been found into a carbonate matrix. This leads naturally to a discussion of the role of such carbonates in panspermia theories. In this context, the present work sets the basis of a criterion to evaluate whether a carbonate matrix in a meteor entering a planetary atmosphere would be able to reach the surface. As a preliminary step, the composition of carbonate minerals in the ALH84001 meteorite is reviewed; in view of the predominance of Mg in these carbonates, pure magnesite (MgCO3) is proposed as a mineral model. This mineral is much more sensitive to high temperatures reached during an entry process, compared with silicates, due to facile decomposition into MgO and gaseous carbon dioxide (CO2). A most important quantity for further studies is therefore the decomposition rate expressed as CO2evaporation rateJ(molecules/m2s). An analytical expression forJ(T) is given using the Langmuir law, based on CO2pressure in equilibrium with MgCO3and MgO at the surface temperatureT. Results suggest that carbonate minerals rich in magnesium may offer much better thermal protection to embedded biological matter than silicates and significantly better than limestone, which was considered in previous studies, in view of the heat absorbed by their decomposition even at moderate temperatures. This first study can be extended in the future to account for more complex compositions, including Fe and Ca.
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Warren, Lorraine. "The Establishment Strikes Back? The Life and Times of Takafumi Horie." International Journal of Entrepreneurship and Innovation 8, no. 4 (November 2007): 261–70. http://dx.doi.org/10.5367/000000007782433222.
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This paper uses newspaper articles to construct an account of the meteoric rise and eventual fall from grace of Takafumi Horie, a Japanese Internet entrepreneur. This trajectory is explored through a qualitative methodology that analyses the content of articles in international newspapers reporting key events in Horie's story. Tracking the representation of Horie as the story develops uncovers the ambiguous nature of the concept of entrepreneurship in Japan, where the enactment of entrepreneurship takes place within and at times against the mainstream of significant change in the nature of work in Japan. The paper concludes by linking Horie's story to the temporal construction of the entrepreneur in a social context in which bureaucratic challenge leads eventually to entrepreneurial marginalization through the likelihood of a jail term. Overall, the paper adds to the literature concerning the mutable and contested nature of the term ‘entrepreneur’.
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Stefănescu, Dan-Paul. "Physical - chemical interaction of injection waters with depleted gas formations." MATEC Web of Conferences 343 (2021): 09006. http://dx.doi.org/10.1051/matecconf/202134309006.
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In order that the physical - chemical interaction of the injection water with the porous-permeable or fissured medium of reservoirs do not lead to their degradation, it is necessary that the waters to meet a number of quality conditions. The treatment and conditioning of the injectable waters is imperative to do so due to the fact that their provenance is different, such as reservoir waters, wastewater resulting from various operations – petroleum operations, meteoric waters, etc. and, in particular, due to the very large volumes of injected water. Failure to follow the steps associated with the water treatment process inevitably leads to premature reduction of the injection wells receptivity. This aspect, as well as another, will be analysed in the context of this article. The injection of water in different geological formations, usually highly depleted, is a connected and defining one in the process of extraction of natural gas from reservoirs. The claim is based on the fact that the very large volumes of reservoir water taken from natural gas stream must be stored safely, otherwise their free discharge would create a real ecological catastrophe
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Edwards, T. W. D., R. O. Aravena, P. Fritz, and A. V. Morgan. "Interpreting paleoclimate from l8O and 2H in plant cellulose: comparison with evidence from fossil insects and relict permafrost in southwestern Ontario." Canadian Journal of Earth Sciences 22, no. 11 (November 1, 1985): 1720–26. http://dx.doi.org/10.1139/e85-180.
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The oxygen-isotope content of terrestrial plant cellulose is related to that of the source waters by a two-step process involving evapotranspirative leaf-water enrichment and equilibrium isotopic exchange between leaf water and atmospheric carbon dioxide. A combination of two models that describe these steps yields consistent agreement between measured and predicted climatic and isotopic data. Humidity is the dominant influence on variations in the cellulose 18O enrichment relative to the source water. A good first-order approximation of the average daytime relative humidity during the growth season at a site can be based on the linear correlation that exists between humidity and cellulose enrichment, without explicit consideration of factors such as temperature, δ18O of atmospheric vapour, and leaf boundary-layer dynamics.The value of the combined model for paleoclimatic reconstruction has been tested using fossil wood from a late glacial site at Brampton, Ontario. Estimates of the past relative humidity were derived from the divergence between measured δ18O values of fossil wood cellulose and environmental water isotopic compositions inferred from the carbon-bound deuterium contents of the cellulose. Growing conditions were apparently substantially drier than those at present between about 11 500 and 8700 years BP, at a time when coniferous forests predominated in southwestern Ontario. A shift in the inferred meteoric water composition over this period suggests a gradual increase in mean annual temperature of about 2 or 3 °C, in agreement with estimates of temperature change based on paleoentomological data.
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Wöhler, C., A. Grumpe, M. Bhatt, A. A. Berezhnoy, V. V. Shevchenko, and A. Bhardwaj. "Detection of an excessively strong 3-μm absorption near the lunar highland crater Dufay." Astronomy & Astrophysics 630 (October 2019): L7. http://dx.doi.org/10.1051/0004-6361/201935927.
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Using the near-infrared spectral reflectance data of the Chandrayaan-1 Moon Mineralogy Mapper (M3) instrument, we report an unusually bright structure of 30 × 60 km2 on the lunar equatorial farside near crater Dufay. At this location, the 3-μm absorption band feature, which is commonly ascribed to hydroxyl (OH) and/or water (H2O), at local midday is significantly (∼30%) stronger than on the surrounding surface and, surprisingly, stronger than in the illuminated polar highlands. We did not find a similar area of excessively strong 3-μm absorption anywhere else on the Moon. A possible explanation for this structure is the recent infall of meteoritic or cometary material of high OH/H2O content forming a thin layer detectable by its pronounced 3-μm band, where a small amount of the OH/H2O is adsorbed by the surface material into binding states of relatively high activation energy. Detailed analysis of this structure with next-generation spacecraft instrumentation will provide further insight into the processes that lead to the accumulation of OH/H2O in the lunar regolith surface.
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Odonne, Francis, Daniel Beaufort, Romain Munck, Laure Bourrières, and José Darrozes. "Smectite as a marker of telogenetic process along structural heterogeneities of sedimentary basin: case study of the Eocene submarine slide surfaces of the Ainsa Basin." Bulletin de la Société géologique de France 188, no. 4 (2017): 22. http://dx.doi.org/10.1051/bsgf/2017186.
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Fluid circulation in sedimentary basins is responsible for the transformation and cementation of mineral grains during diagenesis. Concretions and pipe chimneys are obvious features resulting from such circulation but some transformations in the matrix of rocks, if less spectacular, may lead to pervasive transformations of the sediments. Inherited slide surfaces in the Eocene Ainsa Basin (Spanish Pyrenees) have been chosen to test this hypothesis. In the Sobrarbe delta, the steady mineralogy of marls indicates homogeneity of the sedimentary source. Enrichment of montmorillonite is only observed close to scar surfaces and in the infilling of the scars. Scanning electron microscope (SEM) observation reveals that smectites are formed by in situ replacement of detrital mafic minerals resulting by transformation of detrital minerals under the action of cold sedimentary fluids, lower than 75 °C. The indications of low temperature conditions and local fluid circulation both support a meteoric origin of the fluids postdating the burial history, probably during an exhumation of the basin associated with the tectonic uplift. The higher smectite contents in the infilling of scars and along the unconformities of slide surfaces reveals enhanced circulation of fluids in under-consolidated sediments and the effective fluid circulation pathways along inherited slide surfaces.
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Snelgrove, Jenna R., James M. Buttle, Matthew J. Kohn, and Dörthe Tetzlaff. "Co-evolution of xylem water and soil water stable isotopic composition in a northern mixed forest biome." Hydrology and Earth System Sciences 25, no. 4 (April 21, 2021): 2169–86. http://dx.doi.org/10.5194/hess-25-2169-2021.
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Abstract. Plant–soil water isotopic dynamics in northern forests have been understudied relative to other forest types; nevertheless, such information can provide insight into how such forests may respond to hydroclimatic change. This study examines the co-evolution of xylem water and soil water stable isotopic compositions in a northern mixed forest in Ontario, Canada. Gross precipitation, bulk soil water and xylem water were sampled from pre-leaf out to post-senescence in 2016 for eastern white cedar, eastern hemlock, red oak and eastern white pine. Near-bole soil water contents and mobile soil water isotopic compositions were measured for the last three species. Mobile soil water did not deviate significantly from the local meteoric water line (LMWL). In contrast, near-surface bulk soil water showed significant evaporative enrichment relative to the LMWL from pre-leaf out to peak leaf out under all tree canopies, while xylem water was significantly depleted in 18O and particularly 2H relative to bulk soil water throughout the growing season. Inter-species differences in deviation of xylem water from the LMWL and their temporal changes emerged during the growing season, with coniferous species xylem water becoming isotopically enriched, while that of red oak became more depleted in 2H and 18O. These divergences occurred despite thin soil cover (generally <0.5 m depth to bedrock) which would constrain inter-species differences in tree rooting depths in this landscape. Isotopic fractionation at the tree root and fractionation of xylem water via evaporation through the tree bark are among the most plausible potential explanations for deviations between xylem and soil water isotopic compositions. Differences in the timing and intensity of water use between deciduous and coniferous trees may account for inter-specific variations in xylem water isotopic composition and its temporal evolution during the growing season in this northern forest landscape.
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Jiang, Junsheng, Shunbao Gao, Youye Zheng, David R. Lentz, Jian Huang, Jun Liu, Kan Tian, and Xiaojia Jiang. "Geological, Geochemical, and Mineralogical Constraints on the Genesis of the Polymetallic Pb-Zn-Rich Nuocang Skarn Deposit, Western Gangdese, Tibet." Minerals 10, no. 10 (September 23, 2020): 839. http://dx.doi.org/10.3390/min10100839.
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The Nuocang Pb-Zn deposit is a newly discovered polymetallic skarn deposit in the southern Lhasa subterrane, western Gangdese, Tibet. The skarn occurs at the contact between the limestone of Angjie Formation and the Linzizong volcanic rocks of Dianzhong Formation (LDF), and the subvolcanic granite porphyry intruding those formations; the contact metasomatic skarn is well zoned mineralogically and texturally, as well as geochemically. The skarn minerals predominantly consist of an anhydrous to hydrous calc-silicate sequence pyroxene–garnet–epidote. The endoskarn mainly consists of an assemblage of pyroxene, garnet, ilvaite, epidote, and quartz, whereas the exoskarn is characterized proximal to distally, by decreasing garnet, and increasing pyroxene, ilvaite, epidote, chlorite, muscovite, quartz, calcite, galena, and sphalerite. Geochemical analyses suggest that the limestone provided the Ca for all the skarn minerals and the magmatic volatiles were the main source for Si (except the skarnified hornfels/sandstone, and muscovite-epidote-garnet-pyroxene skarn possibly from the host sandstones), with Fe and Mn and other mineralizing components. During the hydrothermal alteration, the garnet-pyroxene skarn and pyroxene-rich skarn gained Si, Fe, Mn, Pb, Zn, and Sn, but lost Ca, Mg, K, P, Rb, Sr, and Ba. However, the skarnified hornfels/sandstone, and muscovite-epidote-garnet-pyroxene skarn gained Fe, Ca, Mn, Sr, Zr, Hf, Th, and Cu, but lost Si, Mg, K, Na, P, Rb, Ba, and Li. The REEs in the skarn were sourced from magmatic fluids during the prograde stage. Skarn mineral assemblages and geochemistry indicate the skarn in the Nuocang deposit were formed in a disequilibrated geochemical system by infiltrative metasomatism of magmatic fluids. During the prograde stage, garnet I (And97.6Gro1.6) firstly formed, and then a part of them incrementally turned into garnet II (And64.4Gro33.8) and III (And70.22Gro29.1). The subsequent substitution of Fe for Al in the garnet II and III indicates the oxygen fugacity of the fluid became more reduced, then resulted in formation of significant pyroxene. However, the anisotropic garnet IV (And38.5Gro59.8) usually replaced the pyroxene. In the retrograde stage, the temperature decreased and oxygen fugacity increased, but hydrolysis increased with epidote, ilvaite, chlorite I, and muscovite forming with magnetite. The continuing decreasing temperature and mixing with meteoric water lead to Cu, Pb, and Zn saturation as sulfides. After the sulfides deposition, the continued mixing with large amounts of cold meteoric water would decrease its temperature, and increase its pH value (neutralizing), promoting the deposition of significant amounts of calcite and chlorite II. The geological, mineralogical, and geochemical characteristics of Nuocang skarn, suggest that the Nuocang deposit is of a Pb-Zn polymetallic type. Compared to the other typical skarn-epithermal deposits in the Linzizong volcanic area, it indicates that the Nuocang deposit may have the exploration potential for both skarn and epithermal styles of mineralization.
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D’Angelo, M., S. Cazaux, I. Kamp, W. F. Thi, and P. Woitke. "Water delivery in the inner solar nebula." Astronomy & Astrophysics 622 (February 2019): A208. http://dx.doi.org/10.1051/0004-6361/201833715.
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Context. Endogenous or exogenous, dry or wet, various scenarios have been depicted for the origin of water on the rocky bodies in our solar system. Hydrated silicates found in meteorites and in interplanetary dust particles, together with observations of abundant water reservoirs in the habitable zone of protoplanetary disks, are evidence that support aqueous alteration of silicate dust grains by water vapor condensation in a nebular setting. Aims. We investigate the thermodynamics (temperature and pressure dependencies) and kinetics (adsorption rates and energies, surface diffusion and cluster formation) of water adsorption on surfaces of forsterite grains, constraining the location in the solar nebula where aqueous alteration of silicates by water vapor adsorption can occur efficiently and leads to the formation of phyllosilicates. We analyze the astrophysical conditions favorable for such hydration mechanism and the implications for water on solid bodies. Methods. The protoplanetary disk model (ProDiMo) code is tuned to simulate the thermochemical disk structure of the early solar nebula at three evolutionary stages. Pressure, temperature, and water vapor abundance within 1 au of the protosun were extracted and used as input for a Monte Carlo code to model water associative adsorption using adsorption energies that resemble the forsterite [1 0 0] crystal lattice. Results. Hydration of forsterite surfaces by water vapor adsorption could have occurred within the nebula lifetime already at a density of 108 cm−3, with increasing surface coverage for higher water vapor densities. Full surface coverage is attained for temperatures lower than 500 K, while for hotter grain surfaces water cluster formation plays a crucial role. Between 0.5 and 10 Earth oceans can arise from the agglomeration of hydrated 0.1 μm grains into an Earth-sized planet. However, if grain growth occurs dry and water vapor processes the grains afterward, this value can decrease by two orders of magnitude. Conclusions. This work shows that water cluster formation enhances the water surface coverage and enables a stable water layer to form at high temperature and low water vapor density conditions. Finally, surface diffusion of physisorbed water molecules shortens the timescale for reaching steady state, enabling phyllosilicate formation within the solar nebula timescale.
Dissertations / Theses on the topic "Meteorite lead content"
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Arden, John Walter. "Lead in the early solar system." Thesis, University of Oxford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.257664.
Full textBooks on the topic "Meteorite lead content"
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LeMoine, Genevieve, and Christyann Darwent. Development of Polar Inughuit Culture in the Smith Sound Region. Edited by Max Friesen and Owen Mason. Oxford University Press, 2016. http://dx.doi.org/10.1093/oxfordhb/9780199766956.013.43.
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The Inughuit of northwestern Greenland are the most northerly indigenous people in the world. They have long been of interest to scholars and the general public due to their evident isolation when first contacted by Europeans in 1818, their loss of key hunting technologies such as kayaks and bows and arrows before contact, their extensive use of meteoric iron, and their important role in exploration of the far north. This chapter summarizes the archaeological record from the thirteenth century, when Thule migrants first arrived in the region, through the historic period. The key period of emerging Inughuit culture, between the sixteenth and nineteenth centuries, has left few archaeological remains. Work by the Inglefield Land Archaeology Project and studies in ethnohistory and paleoclimatology suggest that many factors, including epidemics and environmental changes associated with the Little Ice Age, led to the distinctive Inughuit culture described by explorers in the nineteenth century.
Book chapters on the topic "Meteorite lead content"
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Squires, Kirsty E. "Come Rain or Shine? The Social Implications of Seasonality and Weather on the Cremation Rite in Early Anglo-Saxon England." In Cremation and the Archaeology of Death. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198798118.003.0022.
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Limited information is available pertaining to the weather and seasonal conditions of early Anglo-Saxon England. Environmental evidence and documentary sources indicate a downturn in climatic conditions from the fifth though to the early seventh century (Lamb 1981: 57–61; Carver 1989: 142; Dark 2000: 27–8; Hooke 2011: 315–16). This period was dominated by wet and cold conditions, which is in stark contrast to the preceding warmer and drier climate of Roman Britain (Dark 2000: 27). Documentary records from the Continent, dating from the fifth to the ninth century, reference several severe winters which seem to have increased in severity from the fifth through to the seventh century (Brooks 1949: 310–11). A particularly wet and cold year would have decreased agricultural output and made food storage extremely difficult (Koepke and Baten 2005: 147). These factors would have resulted in seasonal scarcities and, in the most severe of cases, famine would have ensued resulting in increased mortality rates. Environmental catastrophes would have also had a similar effect on human populations. The starkest example from this period has been dated to AD 536. It is thought that volcanic eruptions or extraterrestrial impacts from meteorites or comets led to environmental and socio-economic crises, particularly in Scandinavia (Gräslund and Price 2012: 431). Dendrochronology and literary sources provide evidence for lower temperatures, increased rainfall, and famine subsequent to this event, whilst social changes, such as the migration of villages to higher ground due to rising water levels and the adoption of new ideologies and funerary rites, have been associated with this environmental disaster (ibid.: 430, 432, 437–8). Seasonality also has an impact on health and disease. In unfavourable weather conditions and freezing temperatures, people are more inclined to spend longer periods of time indoors during the winter months (Roberts and Cox 2003: 37). In addition to the effects of the cold and wet conditions, increased time indoors can contribute to respiratory infections, such as influenza, the common cold, and sinusitis (ibid.: 37, 173). These conditions would have been made worse in early medieval homes due to indoor pollution from hearths and poor ventilation of these buildings.