arXiv subjects

Jonas Pape

Publications and source records attributed to Jonas Pape.

6 recordsLinked to original sources

arXiv2026

The NC-CC dichotomy in ruthenium isotopes: Implications for the origin of the late veneer

High-precision mass-independent Ru isotope data for iron meteorites reveal that in three-isotope diagrams including the p-process Ru nuclides 96Ru or 98Ru, non-carbonaceous (NC) meteorites plot along an s-process mixing line, while the carbonaceous (CC) type irons plot as a cluster off the NC-line. As previously observed for Mo, this offset can be accounted for by an r-process excess in CC over NC materials. As a highly siderophile element, Ru in the bulk silicate Earth (BSE) is thought to predominantly derive from the late veneer, making the Ru isotope dichotomy a powerful genetic tracer of Earth's late accretionary epoch. The BSE and the isotopically anomalous Itsaq Gneiss Complex as defined in prior studies plot on the NC-line defined in this study, suggesting a predominantly NC late veneer that may have evolved over time from more s-process-enriched to more s-process-depleted compositions. However, more precise 96Ru and 98Ru measurements of the BSE's composition are needed to more reliably determine the genetic heritage of the late veneer and to quantify as to whether it contains CC material.

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arXiv2026

Origin of nucleosynthetic isotope variability in the NC reservoir: Evidence from Ti, Cr, and Mo isotopes

Nucleosynthetic isotope anomalies allow distinguishing between non-carbonaceous (NC) and carbonaceous (CC) type meteorites, and have revealed correlated isotope variations especially among NC bodies. Understanding the origin of this NC trend is important for identifying the processes that produced the NC isotope heterogeneity, and for using these isotope anomalies to reconstruct the early evolution of the solar protoplanetary disk. We report mass-independent Ti, Cr, and Mo isotope compositions for a comprehensive set of previously not or only poorly investigated meteorites, as well as acid leachates obtained from the sequential digestion of primitive ordinary chondrites. Some of the samples investigated in this study fill previously identified apparent gaps in the NC trend, suggesting these gaps reflect unrepresentative sampling of a more continuous isotopic trend. Bulk meteorites and leachates exhibit distinct isotope systematics, indicating that the NC isotope variability does not reflect selective thermal processing of presolar carriers in the disk. The NC trend also cannot reflect the continuous addition of CC dust from the outer to the inner disk, because early- and late-formed NC meteorites display largely overlapping isotopic compositions. Instead, we find that the NC isotope heterogeneity is best accounted for by fractionation and mixing among chemically and isotopically distinct dust components, similar to the processes that produced the isotopic variability among carbonaceous chondrites. On this basis we argue for the presence of substructures in the inner disk, which facilitated fractionation and mixing among distinct dust components, and helped preserve a long-lived dust reservoir from which NC planetesimals accreted over an extended period of time.

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arXiv2026

From Dust to Planets -- A Chemical Perspective

Chemical and chronological information preserved in meteorites permits the reconstruction of events and processes in the solar nebula from the formation of the first solids to the accretion of planetary bodies and their subsequent differentiation. The path from a gas-dust cloud to differentiated planets includes intervals of steady evolution interrupted by singular events that dramatically altered this steady path, leading to planetary bodies with distinct chemical compositions and different degrees of internal differentiation. The dominant continuous process in the early Solar System was the cooling of the gas-dust cloud, which caused a steady condensation of elements into solid compounds and a continuous increase in the dust/gas ratio. Planetesimal formation started within less than 1 Ma of Solar System formation and continued for ca. 3 Ma apparently in random regions within the disk. The first planetesimals most likely formed due to streaming instabilities and created gaps in the gas-dust disk that prevented significant element exchange. Later planetesimals formed by accretion of chondrules that had developed in the dust rings by bow shocks. The Earth formed by early accretion of volatile-poor material and a later collision with a Mars-sized volatile richer body after proto-Earth had formed a metal core. This chance event provided the chemical conditions that transformed the Earth into a habitable planet.

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arXiv2023

Isotopic constraints on genetic relationships among group IIIF iron meteorites, Fitzwater Pass, and the Zinder pallasite

Complex interelement trends among magmatic IIIF iron meteorites are difficult to explain by fractional crystallization and have raised uncertainty about their genetic relationships. Nucleosynthetic Mo isotope anomalies provide a powerful tool to assess if individual IIIF irons are related to each other. However, while trace-element data are available for all nine IIIF irons, Mo isotopic data are limited to three samples. We present Mo isotopic data for all but one IIIF irons that help assess the genetic relationships among these irons, together with new Mo and W isotopic data for Fitzwater Pass (classified IIIF), and the Zinder pallasite (for which a cogenetic link with IIIF irons has been proposed). After correction for cosmic-ray exposure, the Mo isotopic compositions of the IIIF irons are identical within uncertainty and confirm their belonging to carbonaceous chondrite-type (CC) meteorites. The mean Mo isotopic composition of Group IIIF overlaps those Groups IIF and IID, but a common parent body for these groups is ruled out based on distinct trace element systematics. The new Mo isotopic data do not argue against a single parent body for the IIIF irons, and suggest a close genetic link among these samples. By contrast, Fitzwater Pass has distinct Mo and W isotopic compositions, identical to those of some non-magmatic IAB irons. The Mo and W isotope data for Zinder indicate that this meteorite is not related to IIIF irons, but belongs to the non-carbonaceous (NC) type and has the same Mo and W isotopic composition as main-group pallasites.

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arXiv2021

Early differentiation of magmatic iron meteorite parent bodies from Mn-Cr chronometry

Magmatic iron meteorite groups such as IIAB, IIIAB and IVA, represent the largest sampling of extraterrestrial core material from the earliest accreted distinct planetary bodies in the solar system. Chromium isotope compositions of chromite/daubreelite from seven samples, translated into 53Cr/52Cr model ages, provide robust time information on planetary core formation. These ages range within 1.5 Ma after formation of calcium-aluminium-rich inclusions (CAIs) and define the time of metal core formation in the respective parent bodies, assuming metal-silicate separation was an instantaneous event that induced strong chemical fractionation of Mn from the more siderophile Cr. The early core formation ages support accretion and differentiation of the magmatic iron meteorite parent bodies to have occurred prior to the chondrule formation interval. The calibration of Mn-Cr ages with established Hf-W ages of samples from the same magmatic iron meteorite groups constrains the initial E53Cr of the solar system to -0.30, and thus lower than previously estimated.

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arXiv2021

Collisional mixing between inner and outer solar system planetesimals inferred from the Nedagolla iron meteorite

The ungrouped iron meteorite Nedagolla is the first meteorite with bulk Mo, Ru, and Ni isotopic compositions that are intermediate between those of the non-carbonaceous (NC) and carbonaceous (CC) meteorite reservoirs. The Hf-W chronology of Nedagolla indicates that this mixed NC-CC isotopic composition was established relatively late, more than 7 million years after Solar System formation. The mixed NC-CC isotopic composition is consistent with the chemical composition of Nedagolla, which combines signatures of metal segregation under more oxidizing conditions (relative depletions in Mo and W), characteristic for CC bodies, and more reducing conditions (high Si and Cr contents), characteristic for some NC bodies, in a single sample. These data combined suggest that Nedagolla formed as the result of collisional mixing of NC and CC core material, which partially re-equilibrated with silicate mantle material that predominantly derives from the NC body. These mixing processes might have occurred during a hit-and-run collision between two differentiated bodies, which also provides a possible pathway for Nedagolla's extreme volatile element depletion. As such, Nedagolla provides the first isotopic evidence for early collisional mixing of NC and CC bodies that is expected as a result of Jupiter's growth.

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