Abstract: Introduction: UltraCarbonaceous Antarctic Mi-croMeteorites (UCAMMs) are interplanetary dust particles that exhibit large concentrations of organic matter with high N concentrations and extreme D/H ratios [1-4]. The mineralogy, the elemental and isotopic composition of UCAMMs indicate that they most likely originate from the cometary reservoir [1, 2, 5]. Most UCAMMs exhibit large variations on D/H, 15 N/ 14 N and 13 C/ 12 C ratios at the micron or sub-micron scale. These isotopic fractionations are carried by the organic matter and their origin is still an open question. We showed that the precursors of UCAMMs can be formed by irradiation with high energy ions of N-rich ice mixtures with hydrocarbons, a process likely to take place at the surface of icy bodies orbiting beyond a nitrogen snow line and irradiated by galactic cosmic rays [2, 6]. Recent experimental simulations showed that the irradiation itself does not induce large D fractionation, but that the refractory organic residue resulting from irradiation of isotopically heterogeneous ice mixtures can exhibit large D/H spatial variation at the micron scale [7]. We performed a new series of experiments on D, 15 N and 13 C labelled ices to study the transmission of the isotopic labelled ice layers to the irradiation-induced residue. Material and method: Irradiation experiments of ices were conducted with the low-energy beam (Irrsud, 0.5-1 MeV/n) at GANIL (Caen, France). We used the IGLIAS experimental setup [8] which allows to deposit and irradiate complex ice films mixtures on substrate windows held at temperatures ranging from 8K to 300K (Figure 1). The evolution of the ices during the irradiation was monitored in situ with a Brucker Vertex 70v Fourier transform infrared (FTIR) spectrometer. The gas mixtures deposited are controlled with a Quadrupole Mass Spectrometer (QMS). We followed the same protocol as described in [7]. We first irradiated a mixture of ices made of two equally thick layers of 14 N2-CH4 (90:10) of about 5 µm each surrounding a thin layer of isotopically labeled (in D, 13 C and 15 N) ice with a thickness of about 0.2 µm. The ice films were formed by gas injections on ZnSe windows at 8K. The thickness of the central isotopically labeled ice layer was estimated from the volume of gases injected (i.e. 2% of the total thickness). The overall thickness of the ice sandwiches (11 µm) were

Abstract: This paper shows how a society imagines human individuals and their power to act upon spirits both ritually and materially. Based on the author’s fieldwork (from 1994 to 2019), it analyzes the emic concept onnir, which is omnipresent in the daily activities and the past and present collective/individual rituals of Siberian Evenki and Even. Each human owns a specific fluctuating “charge made of spirits” and an “active imprint” that empowers the human to act, perform rituals, develop talents, and create. Even after death, this “imprint” affects everything and everyone a human ever touched. Onnir defines the interrelations between the individual, the spirits of his or her own “charge,” and the spirits of the universe in an “active agent”-“patient” relationship. This paper contributes to studies of the notions of the individual, “playing” as a ritual means, the acceptance/rejection of neoshamans, neorituals, and the (ritual) agency of ordinary individuals.

Abstract: In 2011, the discovery of shatter cones confirmed the 28 km diameter Tunnunik complex impact structure, Northwest Territories, Canada. This study presents the first results of ground-based electromagnetic, gravimetric, and magnetic surveys over this impact structure. Its central area is characterized by a 10 km wide negative gravity anomaly of about 3 mGal amplitude, roughly corresponding to the area of shatter cones, and associated with a positive magnetic field anomaly of 120 nT amplitude and 3 km wavelength. The latter correlates well with the location of the deepest uplifted strata, an impact-tilted Proterozoic dolomite layer of the Shaler Supergroup exposed near the center of the structure and intruded by dolerite dykes. Locally, electromagnetic field data unveil a conductive superficial formation which corresponds to an 80–100 m thick sand layer covering the impact structure. Based on the measurements of magnetic properties of rock samples, we model the source of the magnetic anomaly as the magnetic sediments of the Shaler Supergroup combined with a core of uplifted crystalline basement with enhanced magnetization. More classically, the low gravity signature is attributed to a reduction in density measured on the brecciated target rocks and to the isolated sand formations. However, the present-day fractured zone does not extend deeper than 1 km in our model, indicating a possible 1.5 km of erosion since the time of impact, about 430 Ma ago.

Abstract: In this paper, we provide a comprehensive overview of the state-of-knowledge of dust flux and variability in time and space in different sectors of East Antarctica during the Holocene. By integrating the literature data with new evidences, we discuss the dust flux and grain-size variability during the current interglacial and its provenance in the innermost part of the East Antarctic plateau as well as in peripheral regions located close to the Transantarctic Mountains. The local importance of aeolian mineral dust aerosol deflated from low-elevation areas of peripheral East Antarctica is also discussed in the light of new data from several coastal, low-elevation sites.