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We measured the concentrations and isotopic compositions of He, Ne, Ar, Kr, and Xe in a 60.36 mg sample of the Sołtmany meteorite (L6), which fell in northeastern Poland in 2011. The Kr and Xe data suggest a mixture of atmospheric contamination and Q. Using cosmogenic 21Ne and 38Ar concentrations, Sołtmany’s cosmic-ray exposure (CRE) age was determined to be ~29.2 Ma. The preatmospheric radius for Sołtmany was equal to or less than approximately 15 cm and the sample studied here most likely came from close to the preatmospheric surface of the meteoroid. While the 40Ar gas retention age is about 4137 Ma, the 4He gas retention age is 1610 Ma, suggesting loss of a major 4He fraction likely during an impact and/or degassing event on the Sołtmany parent body prior to the ejection of the Sołtmany meteorite ~29.2 Ma ago.
A set of rate equations have been tested against a more robust set of Time-Dependent Density Matrix (TDDM) equations [D. P. W. Middleton, L. A. A. Nikolopoulos, J. Mod. Opti. 59, 1650 (2012)] by using them to determine the populations of ion species and autoionising states (AIS) in noble gas atoms when interacting with a strong external field. Two field shapes were tested here - sinusoidal and square - and a variety of pulse characteristics were examined, i.e. intensity, duration and photon energy, for the neon atomic system. It was found that the rate equations were sufficiently accurate only when the external field is way off-resonant with the AIS. Moreover, analytical solutions of the rate equations in the square pulse case agree with the numerical solutions for a time-dependent pulse containing many cycles. An attempt to model a stochastic field was also made and it was found that the use of such a field diminished and broadened the ion yield ratio due to the presence of an added bandwidth.
Content available remote Nanodiamonds in meteorites: properties and astrophysical context
Purpose: This contribution provides an overview on properties and origin of nanodiamonds in primitive meteorites. Nanodiamond are a type of stardust, i.e. “pre-solar” grains that formed in the outflows or ejecta of stars. Design/methodology/approach: We summarize previously obtained results and include our results dealing with recoil loss from nanoparticles during radioactive decay of trace elements within them. Findings: Nanodiamonds in primitive meteorites have a mean size of ~2.6 nm and an abundance reaching up to ~0.15 % by weight. They contain trace noble gases, notably xenon, with an unusual isotopic composition. The latter is reminiscent of the p- and r-processes of nucleosynthesis that are thought to occur during supernova explosions. Our new results show that recoil loss during â decay of implanted 22Na does not exceed what is expected from energy distribution and range-energy relations in matter. While a CVD origin for the diamonds appears likely (but is not assured), the noble gases were probably introduced by ion implantation. Research limitations/implications: The isotopic pattern of Xe contained in nanodiamonds indicates some unconventional types of element synthesis in stars or modification by secondary processes. Recoil loss from nanometer-sized grains during decay of unstable precursor nuclides has been suggested as an explanation, but our experiments do not support this idea. Originality/value: Other processes must be invoked for explanation of the isotopically unusual xenon trapped in meteoritic nanodiamonds. Ion implantation experiments suggest of “trapped” cosmic ray 3He for deriving an age for the diamonds.
The detailed research of a gas mixture released from the thermal water, which is extracted from borehole KT-1 at Karpniki, showed the predominance of nitrogen (98.08% by volume) with subordinate Ar (1.52%) and He (0.32%) and trace amounts of CO2 (0.07%) and CH4 (0.01%). The 222Rn radionuclide is also dissolved in this water, showing an activity concentration of 245 Bq/dm3 at the outflow and 256 Bq/dm3 in the aquifer. A small value of the gas exponent (0.014), and also a value of the δ coefficient close to 1 (0.93) were calculated based on the dissolved Ar and N2 content in the water examined, as well as on concentrations of argon and nitrogen in water, assuming that atmospheric air is present above the water surface with a contemporary composition and under normal pressure. The data obtained indicate that these gases and additionally CO2 and CH4 are of atmospheric origin. These gases were either dissolved in rainwater, which infiltrated deep into the Karkonosze granite massif, orformed within the organic layer covering this exposed intrusion. This is evidenced by concentrations of these gases that can be comparable to their atmospheric equivalents. Helium is a radiogenic gas formed as a result of nuclear transformation of isotopes assigned to natural radioactive series. The radiogenic and also radioactive gas is represented by the 222Rn radioisotope which is released from reservoir rocks, in an amount of 5% of the atom poolforming in the reservoir rock, into thermal water that subsequently reaches borehole KT-1 from a distance of 34 m at most. The thermal paleoinfiltration water has been heated up as a result of the conduction, and the source of heat is the temperature of the rocks resulting from an average geothermal gradient of 2.96°C per 100 m. The results of the authors’research indicate that there are no traces of inflow of hotfluids (especially water) from the deeper layers of the crust or from the mantle. If the examined thermal water is considered as paleoinfiltration water, its static resources may be limited, non-renewable.
Content available Chondryt Sołtmany
The Sołtmany hammer meteorite is classified as an ordinary chondrite type L6, W0, S2. At present it is the most thoroughly and comprehensively examined Polish meteorite. A comprehensive petrological, mineralogical and geochemical analysis alongside the investigation of its physical and particularly thermophysical properties, and, most of all, analyses of cosmogenic radionuclides and noble gases isotopes content, as well as the use of a troilite thermometer has made it possible to draw interesting conclusions concerning the genesis and evolution of the parent body and the history of the parent meteoroid and, finally, the Sołtmany meteorite. The present report attempts at summing up the results of studies conducted at several European research centres in the last four years. The age of the the Sołtmany chondrite parent rock has been defined at 4.137 billion years. It was formed at a temperature of up to 440–450 K (about 170°C), probably at a depth of up to 3 to 7 km under the surface of the parent body, i.e. at a pressure of the order of 1–2.4 kbar. Such a low temperature during the accretion, diagenesis and metamorphism of the parent body may point to its complicated development, which may be in part due to collisions of partially melted planetesimals. Like with other type L ordinary chondrites, one can infer that the parent body could have been destroyed about 467 million years ago, at the time of a catastrophic collision which led to the formation of Gefion family of planetoids. Perhaps one of the bodies in this family was involved in another collision about 29.2 million years ago, which resulted in ejecting the parent meteoroid of the Sołtmany chondrite onto the Earth collision trajectory. Before entering the Earth’s atmosphere, this meteoroid had the mass of about 36 kg and the diameter of ca 13.5 cm. During its flight through the atmosphere, it rotated and somersaulted, which resulted in the formation of an uniform thin (0.5–0.7 mm) fusion crust, whose temperature reached 1000°C. In the last phase, the Sołtmany meteorite fell almost vertically and its mass was a mere 3% of the mass of the parent meteoroid – 1.066 kg. It hit the roof and then the concrete stairs of a farm building, which caused it to break into two bigger and many small pieces. It was found a few minutes after the fall, which occurred at 6:03 a.m. (CEST, UTC+2:00) on 30 April 2011, by Wydmińskie Lake in northern Poland (54°00,53’N, 22°00,30’E). The Sołtmany chondrite is one of just 14 meteorites in which the activity concentration of the cosmogenic 52Mn has been determined, and one of the few ordinary chondrites where the concentration of organic matter has been defined. As a result, it was found out that unlike in carbonaceous CI chondrites, the composition of organic particles is dominated by less complex compounds (CHO and CHOS) than CHNO and CHNOS compounds. This may indicate the decomposition of more complex organic compounds into particles with simple structures during magmatic and metamorphic processes related to formation of type L ordinary chondrites.
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