Tracing the Origins of Refractory Inclusions - the Solar System's Oldest Solids: a Petrographic, Geochemical and 26Al-26Mg Dating Study of CV and CK Refractory Inclusions

<p>Refractory inclusions in carbonaceous chondrite meteorites are of particular interest because both long- and short-lived chronometers have shown that they are the oldest sampled material to have formed in the Solar System. The objective of this study was to establish high-precision petrographic, chemical and isotopic analyses of refractory inclusions and thus offer insights into the chemical and astrophysical environments present during the formation of the Solar System. The former presence of the short-lived isotope 26Al (T1/2 = ca.730 KYr) has been established in a majority of refractory inclusions. Recent studies using both solution-based and in situ methodologies have suggested that the initial 26Al/27Al0 value of refractory inclusions is ca.6 x 10-5, higher than the established "canonical" value of [5.00 +/- 0.05] x 10-5. Knowing the initial concentration of 26Al within the Solar System provides a useful anchor from which ancient materials can be dated. Petrographic and trace element analyses were performed on nine newly-extracted refractory inclusions from CV3 and CK3 chondrites. These analyses revealed all but three refractory inclusions to have experienced multiple episodes of melting and evaporation prior to crystal closure. Mg isotope analyses were performed on eight of the newly extracted refractory inclusions in addition to five inter-laboratory samples. All refractory inclusions shown to have remained unaltered following crystal-closure, regardless of thermal history prior to closure, yielded a model 26Al/27Al0 of [4.89 x 0.265] x 10-5; within error of the canonical value. This result confirms that 26Al was homogenous and at canonical concentrations in the solar nebula. The results also suggest that chemical fractionation and crystal closure for the analysed refractory inclusions was completed within no more than 160 Kyr.</p>

Tracing the Origins of Refractory Inclusions - the Solar System's Oldest Solids: a Petrographic, Geochemical and 26Al-26Mg Dating Study of CV and CK Refractory Inclusions

<p>Refractory inclusions in carbonaceous chondrite meteorites are of particular interest because both long- and short-lived chronometers have shown that they are the oldest sampled material to have formed in the Solar System. The objective of this study was to establish high-precision petrographic, chemical and isotopic analyses of refractory inclusions and thus offer insights into the chemical and astrophysical environments present during the formation of the Solar System. The former presence of the short-lived isotope 26Al (T1/2 = ca.730 KYr) has been established in a majority of refractory inclusions. Recent studies using both solution-based and in situ methodologies have suggested that the initial 26Al/27Al0 value of refractory inclusions is ca.6 x 10-5, higher than the established "canonical" value of [5.00 +/- 0.05] x 10-5. Knowing the initial concentration of 26Al within the Solar System provides a useful anchor from which ancient materials can be dated. Petrographic and trace element analyses were performed on nine newly-extracted refractory inclusions from CV3 and CK3 chondrites. These analyses revealed all but three refractory inclusions to have experienced multiple episodes of melting and evaporation prior to crystal closure. Mg isotope analyses were performed on eight of the newly extracted refractory inclusions in addition to five inter-laboratory samples. All refractory inclusions shown to have remained unaltered following crystal-closure, regardless of thermal history prior to closure, yielded a model 26Al/27Al0 of [4.89 x 0.265] x 10-5; within error of the canonical value. This result confirms that 26Al was homogenous and at canonical concentrations in the solar nebula. The results also suggest that chemical fractionation and crystal closure for the analysed refractory inclusions was completed within no more than 160 Kyr.</p>

Carbonaceous Chondrite Outgassing Experiments: Implications for Methane Replenishment on Titan

&lt;p&gt;Titan is the only known moon in the Solar System with a substantial atmosphere of N2 and CH4. However, its origin and evolution are not well understood. Titan&amp;#8217;s present amount of atmospheric CH4 was predicted to be destroyed photochemically on very short timescales (~ 10 Myrs, Yung et al. 1984). This suggests that a methane resupply mechanism is necessary. The Huygens probe GCMS measurements of noble gases suggest that Titan&amp;#8217;s atmosphere is likely linked to its interior instead of being incorporated during formation (Nieman et al., 2005). Recent theoretical modeling works of Titan&amp;#8217;s atmosphere and interior suggest that its atmosphere could have originated partly by outgassing primordial organics in its interior (Neri et al. 2019; Miller et al. 2019). If this theory holds, volatiles like methane could be outgassing from Titan&amp;#8217;s interior to sustain its current observed abundances. Insoluble organic matter (IOM) found in carbonaceous chondrites may serve as an analog for the organic material in Titan&amp;#8217;s interior and provide experimental constraints on the outgassed component of its atmosphere (Thompson et al. 2021). By heating carbonaceous chondrite samples and measuring the abundances of their released volatiles, specifically methane, we may be able to connect what we see in the lab to species in Titan&amp;#8217;s atmosphere today.&lt;/p&gt; &lt;p&gt;We performed outgassing experiments using three primordial CM carbonaceous chondrites: Murchison, Aguas Zarcas, and Jbilet Winselwan. The first two are &quot;fall&quot; meteorite (1969 and 2019), and Jbilet Winselwan is a desert &quot;find'' meteorite (2013). We used two sizes of samples for each CM chondrite for the measurements: a small grain sample with diameters &lt; 20 &amp;#181;m and a normal grain sample with diameters of 20-100&amp;#181;m. Each sample underwent a step heating scheme where they are heated and held at every 100&amp;#176;C from room temperature to 1200&amp;#176; C. The whole heating scheme takes 12 hours. We continuously monitored the partial pressures of 10 outgassed mass peaks using a residual gas analyzer (RGA).&lt;/p&gt; &lt;p&gt;We can estimate how much methane can be outgassed from the insoluble organics in the CM chondrites with the RGA data. We found that chondrite outgassing can resupply methane that can last for ~0.5-2 Gyrs. If organics indeed makes a significant fraction of Titan's interior, outgassing through thermal instability of Titan's interior can potentially resupply Titan's atmospheric methane for a period of time.&lt;/p&gt;

Nano-FTIR spectroscopic identification of prebiotic carbonyl compounds in Dominion Range 08006 carbonaceous chondrite

Meteorites contain organic matter that may have contributed to the origin of life on Earth. Carbonyl compounds such as aldehydes and carboxylic acids, which occur in meteorites, may be precursors of biologically necessary organic materials in the solar system. Therefore, such organic matter is of astrobiological importance and their detection and characterization can contribute to the understanding of the early solar system as well as the origin of life. Most organic matter is typically sub-micrometer in size, and organic nanoglobules are even smaller (50–300 nm). Novel analytical techniques with nanoscale spatial resolution are required to detect and characterize organic matter within extraterrestrial materials. Most techniques require powdered samples, consume the material, and lose petrographic context of organics. Here, we report the detection of nanoglobular aldehyde and carboxylic acids in a highly primitive carbonaceous chondrite (DOM 08006) with ~ 20 nm spatial resolution using nano-FTIR spectroscopy. Such organic matter is found within the matrix of DOM 08006 and is typically 50–300 nm in size. We also show petrographic context and nanoscale morphologic/topographic features of the organic matter. Our results indicate that prebiotic carbonyl nanoglobules can form in a less aqueous and relatively elevated temperature-environment (220–230 °C) in a carbonaceous parent body.