<p>Olivine is an abundant phase of ultramafic and mafic rocks in the earth's crust and mantle. Stony meteorites or stony-iron meteorites like pallasites also contain a lot of extraterrestrial olivines. During atmosphere entry olivine-containing meteorites experience different oxygen levels and intense heating for brief intervals, creating fusion crusts that are a few millimetres thick. As a result, various thermal pathways between the rim and the core are anticipated for meteoritic olivines. This shows different colours in natural pallasitic olivines. We are particularly interested in the effects of environmental variables on both terrestrial and interplanetary olivines, based on terrestrial olivines. Natural volcanic olivines from the 1959 Kilauea eruption in Hawaii, the Aheim mine, Norway, are employed and a stony-iron pallasite (collected 1822 &#8211; Atacama Desert). We generate two environments using a gas-tight tube furnace that produces CO-CO2 gas mixes&#8212;one in air and the second with a reduced atmosphere (fO<sub>2</sub>10<sup>-12</sup> bar). The temperatures range from 950 to 1350 degrees Celsius (i.e. within the olivine stability field). After hand-picking single grains of olivines and putting them in Pt-Rh crucibles for an hour, the samples are lifted vertically out of the tube furnace and quenched in air. EPMA, SEM, RAMAN, and optical and laser microscopy are used to characterise and analyse the samples.</p> <p>Preliminary findings, olivines show thermal stability and have a homogeneous chemical composition both before and after heating. A reduced environmental exposure causes a change in colour, similar to the stony-iron pallasite which will be discussed. In association with those observations, we also see Raman bands nearby 600 cm-1 vanish, and Raman bands show up at 800 cm-1. We will compare these effects in relation to the findings from tests involving air exposure and compare the observations obtained from naturally occurring pallasitic olivines.</p>
<p>Previously unknown class of metalorganic compounds revealed in meteorites [1] also found on the surfaces of silicate phases such as olivine, may have been involved in the emergence of life. &#160;Here, the thermal stability of such organic compounds has been experimentally investigated under conditions which simulate those extant on the early Earth. We have studied olivines from the Hawaiian eruptions of 1959 and 2018. Individual mineral grains have been hand-picked to be free of secondary phases such as pyroxene or melt. We use a high temperature gas-tight tube furnace under CO-CO<sub>2</sub> gas mixture at temperatures ranging from 950&#176;C to 1350&#176;C and oxygen fugacity ranging from 10<sup>-12</sup>&#160;to 10<sup>-10&#160;</sup>bar, within the stability field of olivine. The samples were contained in Pt crucibles and held for dwell times of 1 to 64 h. Quenching was performed by lifting the samples vertically out of the tube furnace. Using EPMA (electron microprobe analyzer) and RAMAN spectroscopy, we have mapped the state of the olivine samples. We observe that the composition of the individual mineral grains remains stable and homogeneous with thermal treatment. We are also investigating the role of impurities and cracks in the natural olivine and synthetic forsterite that might influence our study. The metalorganic cargo of these olivines has been analyzed using FT-ICR-MS (Fourier Transform ion cyclotron mass spectrometry). Preliminary results reveal systematic changes or organic molecular composition depending on time and heat of thermal treatment whose origins will be discussed.</p><p>[1] A. Ruf, B. Kanawati, N. Hertkorn, Q. Yin, F. Moritz, M. Harir, M. Lucio, B. Michalke, J. Wimpenny, S. Shilobreeva, B. Bronsky, V. Saraykin, Z. Gabelica, R. D. Gougeon, E. Quirico, S. Ralew, T. Jakubowski, &#160;H. Haack, M. Gonsior, P. Jenniskens, N. W. Hinman, P. Schmitt-Kopplin. (2017) Previously unknown class of metalorganic compoundsrevealed in meteorites. PNAS 114 (2017) 2819-2824.</p>
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