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- Helbert, Jörn, et al.
(författare)
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A set of laboratory analogue materials for the MERTIS instrument on the ESA BepiColombo mission
- 2007
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Ingår i: Advances in Space Research. - : Elsevier BV. - 0273-1177 .- 1879-1948. ; 40:2, s. 272-279
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Tidskriftsartikel (refereegranskat)abstract
- The MERTIS (Mercury Thermal Imaging Spectrometer) instrument on the ESA mission BepiColombo will study the surface of Mercury in the wavelength range from 7 to 14 pin. The analysis of the MERTIS data will be posing a number of significant challenges. To facilitate the development of analytic tools, support planned ground based observations and facilitate a cross calibration with other instruments on BepiColombo and MESSENGER, a list of Mercury analogue materials was compiled. This set of analogue materials is based on our current knowledge of the surface composition of Mercury and includes plagioclase and potassium feldspars, low and high Ca pyroxenes, olivine, elemental sulfur, and as an extraterrestrial analogue a lunar highland soil sample. The samples are prepared in four different grain size separates ranging from 0 to 250 mu m to cover the expected grain size distribution on the surface of Mercury.
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| 2. |
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| 3. |
- Visser, Robbin, et al.
(författare)
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A short-lived 26Al induced hydrothermal alteration event in the outer solar system : Constraints from Mn/Cr ages of carbonates
- 2020
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Ingår i: Earth and Planetary Science Letters. - : Elsevier BV. - 0012-821X .- 1385-013X. ; 547
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Tidskriftsartikel (refereegranskat)abstract
- A key process in the early solar system that significantly affects the further evolution and transport of highly volatile elements throughout the solar system hydrothermal parent body alteration. To determine whether hydrothermal alteration in outer solar system parent bodies occurred more or less simultaneously or due to a sequence of multiple different events, we investigated low-temperature hydrothermally altered CM and CI chondrites along with volatile-rich CM-like clasts and C1 clasts with abundant mineral phases that contain volatiles. In this respect, C1 clasts are particularly important as they closely resemble the CI chondrites but originate from isotopically different parent bodies. Specifically, we applied the SIMS-based Mn/Cr in situ dating technique to carbonates, a common hydrothermally formed phase in low-temperature hydrothermally altered meteorites. The Mn/Cr ages of dolomites in CI chondrites and C1 clasts as well as calcites in CM chondrites and CM-like clasts reveal that nearly all carbonates in low-temperature hydrothermally altered clasts and chondrites were formed within a brief period between 2-6 Ma after CAI formation. Given this sharp separation, and that hardly any material contains carbonates formed later than ∼6 Ma after CAI formation, hydrothermal alteration likely occurred near-contemporaneously among different parent bodies in the outer solar system. Further, the timing of hydrothermal alteration matches peak heating of 26Al decay that ceased at ∼5 Ma after CAI formation. Hereby, these results are consistent with a model in which the carbonates in low-temperature hydrothermally altered parent bodies precipitated from the fluid produced by melting ice. The results also show that other potential heating events (e.g., impacts) only negligibly contributed to creating environments where fluid-mediated dissolution and precipitation of carbonates was possible. Additionally, the isotopic (H, O, Cr, and S) differences between C1 clasts and CI chondrites are most likely not caused by differences in timing of hydrothermal aqueous alteration and, thus, are best explained by spatially different isotopic reservoirs.
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| 4. |
- Visser, Robbin, et al.
(författare)
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Sulfur isotope study of sulfides in CI, CM, C2ung chondrites and volatile-rich clasts – Evidence for different generations and reservoirs of sulfide formation
- 2019
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Ingår i: Geochimica et Cosmochimica Acta. - 0016-7037 .- 1872-9533. ; 261, s. 210-223
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Tidskriftsartikel (refereegranskat)abstract
- Deciphering aspects of the solar system’s formation process and the origin of planetary bodies can be achieved by examining primitive solar system materials, as these materials reflect the early solar system composition and may represent the building blocks of planetary bodies. Along these lines, knowing the original composition of carbonaceous chondrite meteorites is a valuable asset for determining the conditions in the parent bodies where they formed. Therefore, to determine the key characteristics of the parent bodies from which the carbonaceous chondrites and primitive materials are derived, we examined chemical and sulfur isotope compositions of sulfides in CM, CI and C2ung carbonaceous chondrites as well as from CM- and CI-like volatile-rich clasts; such an investigation allows us to explore the origin of these sulfides and to determine the primordial S composition of their parent body source region. In this study, sulfides from 7 CM, CI, and C2ung carbonaceous chondrites and 16 chondritic and achondritic breccias containing volatile-rich clasts were analyzed by electron microprobe and SIMS. Different sulfides were found, which shows evidence of different formation origins. Based on compositions and exsolution textures, we suggest that one fraction of the sulfides in both clasts and chondrites formed at high temperatures prior to incorporation into the parent body. The other sulfides most likely have a secondary origin and precipitated during fluid–rock interaction. Furthermore, differences in the S isotopic signature of the sulfides in chondrites correlate with the degree of aqueous alteration of the carbonaceous host rocks (CM or CI). Studying the sulfides of the volatile-rich clasts in brecciated chondrites and achondrites, a similar fractionation cannot be seen. Even though the mineralogy of CI chondrites and CI-like clasts is similar, the sulfides in CI chondrites appear to be enriched in heavy isotopes compared to those in the clasts (δ34S + 1‰ (CI) vs −2‰ (CI-like clast). This could have been caused by different alteration conditions, or it represents a different sampling reservoir. In this study a large S isotopic fractionation between pentlandite and pyrrhotite was found in large primarily formed sulfides showing exsolution textures, indicating that pentlandite prefers to incorporate light S isotopes. Considering the S isotope composition of the exsolved phase which can be found in CM- and CI-like clasts, the pristine δ34S value of the original monosulfide solid solution (mss) is estimated to be ∼−2‰. This value possibly resembles the sampling reservoir from which the sulfides formed, indicating that both CM- and CI-like clasts derived from a similar reservoir, and this reservoir is different from the formation reservoir of the CI chondrites.
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