124 results found
Suttle MD, Campanale F, Folco L, et al., 2023, Fossil micrometeorites from Monte dei Corvi: Searching for dust from the Veritas asteroid family and the utility of micrometeorites as a palaeoclimate proxy, GEOCHIMICA ET COSMOCHIMICA ACTA, Vol: 355, Pages: 75-88, ISSN: 0016-7037
Genge MJ, 2023, GAS DRIVEN EJECTION OF HIGH-NICKEL METAL FROM METEORITES DURING ATMOSPHERIC ENTRY: IMPLICATIONS FOR CHONDRULE FORMATION, 86th Annual Meeting of the Meteoritical-Society (MetSoc), Publisher: WILEY, Pages: A102-A102, ISSN: 1086-9379
Boyd MR, Genge MJ, 2023, MICROSPHERULES AS PROXIES FOR LIGHTNING STRIKES, 86th Annual Meeting of the Meteoritical-Society (MetSoc), Publisher: WILEY, Pages: A32-A32, ISSN: 1086-9379
Mattia IS, Suttle MD, Genge MJ, 2023, THE EFFECT OF EARLY DIAGENETIC PROCESSES ON THE QUANTIFICATION OF FOSSIL MICROMETEORITE FLUX IN THE GEOLOGICAL RECORD, 86th Annual Meeting of the Meteoritical-Society (MetSoc), Publisher: WILEY, Pages: A192-A192, ISSN: 1086-9379
Jenkins LEE, Lee MRR, Daly L, et al., 2023, Winchcombe: An example of rapid terrestrial alteration of a CM chondrite, METEORITICS & PLANETARY SCIENCE, ISSN: 1086-9379
Genge MJ, Alesbrook L, Almeida NV, et al., 2023, The fusion crust of the Winchcombe meteorite: A preserved record of atmospheric entry processes, METEORITICS & PLANETARY SCIENCE, ISSN: 1086-9379
Guillaume L, Laurent V, Genge MJ, 2023, Immersive and interactive three-dimensional virtual fieldwork: Assessing the student learning experience and value to improve inclusivity of geosciences degrees, Journal of Geoscience Education, Vol: 71, Pages: 462-475, ISSN: 1089-9995
Fieldwork is a pedagogical cornerstone of many geoscience degrees. During the academic years 2019–20 and 2020–21, the worldwide COVID-19 pandemic made outdoors fieldwork difficult, resulting in an urgent need to develop virtual alternatives. However, there is still more to learn about the impact of teaching fieldwork virtually on the student learning experience. This study aims to assess the student learning experience during immersive and interactive three-dimensional virtual fieldwork and establish the value of digital techniques to improve the inclusivity of geosciences degrees. Quantitative and qualitative data were collected to assess students’ attitudes to virtual fieldwork in comparison to outdoor fieldwork in terms of accessibility, inclusivity and their learning experience. Our results show overall positive student responses to virtual fieldwork, with over half stating it adequately replicated the learning experience of outdoor fieldwork. Students also value outdoor fieldwork for the degree of autonomy it provides, and idea-sharing with peers; yet simultaneously the majority believed outdoor fieldwork is inherently exclusionary. This study concludes that virtual fieldwork, taught using interactive 3D virtual outcrops set within virtual worlds, replicates the outdoor fieldwork learning experience as closely as possible. However, students missed some fundamental and important aspects of outdoor fieldwork, as being outside and the social interactions with peers and staff that are specific to on-location fieldwork. This study recommends the use of virtual fieldwork in addition to residential on-location fieldwork, as for a significant number of students virtual fieldwork may be a better way of accessing this valued pedagogy of the geosciences. Furthermore, virtual fieldwork has the potential to make geosciences more inclusive and attractive to a wider range of students.
Suttle MD, Daly L, Jones RH, et al., 2022, The Winchcombe meteorite-A regolith breccia from a rubble pile CM chondrite asteroid, METEORITICS & PLANETARY SCIENCE, ISSN: 1086-9379
King AJ, Daly L, Rowe J, et al., 2022, The Winchcombe meteorite, a unique and pristine witness from the outer solar system., Science of Advanced Materials, Vol: 8, Pages: 1-17, ISSN: 1947-2935
Direct links between carbonaceous chondrites and their parent bodies in the solar system are rare. The Winchcombe meteorite is the most accurately recorded carbonaceous chondrite fall. Its pre-atmospheric orbit and cosmic-ray exposure age confirm that it arrived on Earth shortly after ejection from a primitive asteroid. Recovered only hours after falling, the composition of the Winchcombe meteorite is largely unmodified by the terrestrial environment. It contains abundant hydrated silicates formed during fluid-rock reactions, and carbon- and nitrogen-bearing organic matter including soluble protein amino acids. The near-pristine hydrogen isotopic composition of the Winchcombe meteorite is comparable to the terrestrial hydrosphere, providing further evidence that volatile-rich carbonaceous asteroids played an important role in the origin of Earth's water.
Daly L, Suttle MD, Lee MR, et al., 2022, A COORDINATED APPROACH TO INVESTIGATE THE HETEROGENEITY OF AQUEOUS ALTERATION AT THE MICRO-SCALE IN THE WINCHCOMBE METEORITE, A CM FALL, Publisher: WILEY, ISSN: 1086-9379
Genge MJ, Alesbrook LS, Almeida NV, et al., 2022, THE FUSION CRUST OF THE WINCHCOMBE METEORITE: VIGOROUS DEGASSING DURING ATMOSPHERIC ENTRY., Publisher: WILEY, ISSN: 1086-9379
Suttle MD, Daly L, Jones RH, et al., 2022, GEOLOGICAL HISTORY OF THE WINCHCOMBE METEORITE - A NEW CM CHONDRITE FALL, Publisher: WILEY, ISSN: 1086-9379
Boyd MR, Genge MJ, Tomkins AG, et al., 2022, LIGHTNING STRIKE SAMPLES FROM THE PILBARA, AUSTRALIA: CRITERIA FOR IDENTIFYING LIGHTNINGOGENIC SPHERULES, 85th Annual Meeting of the Meteoritical-Society, Publisher: WILEY, ISSN: 1086-9379
Joseph R, Bose M, Suttle MD, et al., 2022, A RECONNAISSANCE SURVEY OF MICROMETEORITES FROM ANTARCTICA, 85th Annual Meeting of the Meteoritical-Society, Publisher: WILEY, ISSN: 1086-9379
Rudraswami NG, Pandey M, Genge MJ, et al., 2021, Extraterrestrial dust as a source of bioavailable iron contributing to the ocean for driving primary productivity, METEORITICS & PLANETARY SCIENCE, Vol: 56, Pages: 2175-2190, ISSN: 1086-9379
Chernonozhkin SM, de Vega CG, Artemieva N, et al., 2021, Isotopic evolution of planetary crusts by hypervelocity impacts evidenced by Fe in microtektites, NATURE COMMUNICATIONS, Vol: 12
Wozniakiewicz PJ, Bridges J, Burchell MJ, et al., 2021, A cosmic dust detection suite for the deep space Gateway, ADVANCES IN SPACE RESEARCH, Vol: 68, Pages: 85-104, ISSN: 0273-1177
Van Ginneken M, Goderis S, Artemieva N, et al., 2021, A large meteoritic event over Antarctica ca. 430 ka ago inferred from chondritic spherules from the Sor Rondane Mountains, SCIENCE ADVANCES, Vol: 7, ISSN: 2375-2548
Suttle MD, Folco L, Genge MJ, et al., 2021, The aqueous alteration of GEMS-like amorphous silicate in a chondritic micrometeorite by Antarctic water, GEOCHIMICA ET COSMOCHIMICA ACTA, Vol: 293, Pages: 399-421, ISSN: 0016-7037
Suttle MD, Folco L, Genge MJ, et al., 2020, Flying too close to the Sun - The viability of perihelion-induced aqueous alteration on periodic comets, ICARUS, Vol: 351, ISSN: 0019-1035
Rudraswami NG, Genge MJ, Marrocchi Y, et al., 2020, The Oxygen Isotope Compositions of Large Numbers of Small Cosmic Spherules: Implications for Their Sources and the Isotopic Composition of the Upper Atmosphere, JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS, Vol: 125, ISSN: 2169-9097
Genge MJ, Van Ginneken M, Suttle MD, 2020, Micrometeorites: Insights into the flux, sources and atmospheric entry of extraterrestrial dust at Earth, Planetary and Space Science, Vol: 187, Pages: 1-12, ISSN: 0032-0633
Micrometeorites (MMs) provide constraints on the flux and sources of extraterrestrial dust falling on Earth as well as recording the processes occurring during atmospheric entry. Collections of micrometeorites have been recovered from a wide variety of environments including Antarctic moraine, rock traps, ice and snow and on roof tops in urban areas. Studies of the mineralogy and composition of MMs suggest that most particles (>98%) >50 μm in diameter have asteroidal sources, whilst ~50% of particles smaller than 50 μm are likely to be derived from comets. The relative abundance of S(IV)-type asteroid materials, similar to ordinary chondrites increases with size, although C-type asteroidal materials, similar to carbonaceous chondrites dominate over all. Although MMs provide excellent evidence on the nature and abundance of extraterrestrial dust at the Earth’s orbit they are not without bias and uncertainty. Mineralogical and compositional change during atmospheric entry makes the exact nature of their precursors uncertain complicating evaluation of source beyond basic classes of material. This is particularly true at larger sizes when complete melting to form cosmic spherules occurs, however, unmelted MMs >50 μm in size are also often thermally altered. Mixing with atmospheric oxygen and mass fractionation by evaporation furthermore complicates the use of oxygen isotope compositions in identifying parent bodies. All MM collections are suggested to exhibit biases owing to: (1) collection method, (2) terrestrial weathering, (3) terrestrial contamination, and (4) erosion and deposition by terrestrial surface processes. Even in the least biased collections, those collected by dedicated melting of Antarctic snow, erosive loss of material is suggested here to make fluxes uncertain by factors of up to ~2. The abundance of asteroid-derived MMs observed in collections contradicts models of the orbital evolution of interplanetary dust to Earth, whic
Genge M, 2019, Geological Field Sketches and Illustrations: A Practical Guide, Publisher: Oxford University Press, ISBN: 978-0198835929
Madden-Nadeau AL, Genge MJ, 2019, Fiamme degassing structures and their implications for the post-emplacement temperatures and H2O contents of high-grade ignimbrites, Journal of Volcanology and Geothermal Research, Vol: 384, Pages: 251-262, ISSN: 0377-0273
A new process in post-emplacement ignimbrite degassing is proposed from observations of unusual structures in a high-grade ignimbrite in Sardinia. The structures consist of fiamme decorated above and below by vesicles, termed here Fiamme Degassing Structures (FDS). The relative volumes of vesicles and fiamme have a positive, linear correlation, and the ratio between the volume of vesicles above and below fiamme (asymmetry ratio) is <1 for a significant number of structures. The positive relationship between the volume of fiamme and vesicles implies that the vesicles were produced by the degassing of fiamme post-emplacement. An equal volume of vesicles would be expected above and below fiamme under simple degassing under compression, contrary to observation in many FDS. The low asymmetry ratio is, therefore, related to a secondary process; vesicle loss and capture is proposed as an explanation. A numerical model of vesicle migration within rhyolitic ignimbrites is used to show that vesicles can rise further than the average separation distance between the fiamme, allowing them to be trapped by overlying fiamme. Sufficient migration of vesicles to result in trapping, however, requires a restricted range of H2O contents and temperatures on emplacement (e.g > 1 wt% at <860 °C), explaining the rare occurrence of FDS. The H2O contents required to form these structures post-emplacement are relatively high for pyroclasts, suggesting they are indicators of unusually large supersaturation in water resulting from rapid excavation rate. These structures also illustrate that interaction of volatiles with fiamme occurs during post-emplacement degassing; FDS may act as baffles that channel volatiles into fumarole columns, slowing volatile loss.
Wilson A, Genge M, Krzesińska A, et al., 2019, Atmospheric entry heating of micrometeorites at Earth and Mars: implications for the survival of organics, Meteoritics and Planetary Science, Vol: 54, Pages: 1-19, ISSN: 1086-9379
The atmospheric entry heating of micrometeorites (MMs) can significantly alter their pre-existing mineralogy, texture and organic material. The degree of heating depends predominantly on the gravity and atmospheric density of the planet on which they fall. For particles falling on Earth the alteration can be significant, leading to the destruction of much of the pre-entry organics, however, the weaker gravity and thinner atmosphere of Mars enhances the survival of MMs and increases the fraction of particles that preserve organic material. This paper investigates the entry heating of MMs on the Earth and Mars in order to examine the micrometeorite population on each planet and give insights into the survival of extraterrestrial organic material. The results show that particles reaching the surface of Mars experience a lower peak temperature compared to Earth and, therefore, experience less evaporative mass loss. Of the particles which reach the surface, 68.2% remain unmelted on Mars compared to only 22.8% on Earth. Due to evaporative mass loss, unmelted particles that reach the surface of Earth are restricted to sizes <70 µm whereas particles >475 µm survive unmelted on Mars. Approximately 10% of particles experience temperatures below ~800 K, i.e. the sublimation temperature of refractory organics found in MMs. On Earth this fraction is significantly lower with less than 1% expected to remain below this temperature. Lower peak temperatures coupled with the larger sizes of particles surviving without significant heating on Mars suggests a much higher fraction of organic material surviving to the martian surface.
Tomkins AG, Genge MJ, Tait AW, et al., 2019, High survivability of micrometeorites on Mars: Sites with enhanced availability of limiting nutrients, Journal of Geophysical Research: Planets, Vol: 124, Pages: 1802-1818, ISSN: 2169-9097
NASA's strategy in exploring Mars has been to follow the water, because water is essential for life, and it has been found that there are many locations where there was once liquid water on the surface. Now perhaps, to narrow down the search for life on a barren basalt‐dominated surface, there needs to be a refocusing to a strategy of “follow the nutrients.” Here we model the entry of metallic micrometeoroids through the Martian atmosphere, and investigate variations in micrometeorite abundance at an analogue site on the Nullarbor Plain in Australia, to determine where the common limiting nutrients available in these (e.g., P, S, Fe) become concentrated on the surface of Mars. We find that dense micrometeorites are abundant in a range of desert environments, becoming concentrated by aeolian processes into specific sites that would be easily investigated by a robotic rover. Our modeling suggests that micrometeorites are currently far more abundant on the surface of Mars than on Earth, and given the far greater abundance of water and warmer conditions on Earth and thus much more active weather system, this was likely true throughout the history of Mars. Because micrometeorites contain a variety of redox sensitive minerals including FeNi alloys, sulfide and phosphide minerals, and organic compounds, the sites where these become concentrated are far more nutrient rich, and thus more compatible with chemolithotrophic life than most of the Martian surface.Plain Language SummaryNASA's exploration program has allowed the scientific community to demonstrate clearly that Mars had a watery past, so the search for life needs to move on to identifying the places where water and nutrients coincided. We have investigated the relative abundance of micrometeorites on Mars compared to the Earth because these contain key nutrients that the earliest life forms on Earth used, and because their contained minerals can be used to investigate past atmospheric chemistry. We sugge
Suttle M, Genge M, Salge T, et al., 2019, A microchondrule-bearing micrometeorite and comparison with microchondrules in CM chondrites, Meteoritics and Planetary Science, Vol: 54, Pages: 1303-1324, ISSN: 1086-9379
We report the discovery of a partially altered microchondrule within a fine-grained micrometeorite.This object is circular, <10μm in diameter and has a cryptocrystalline texture, internal zonation and a thin S-bearing rim. These features imply a period of post-accretion parent body aqueous alteration, in which the former glassy igneous texture was subject to hydration and phyllosilicate formation as well as leaching of fluid-mobile elements. We compare this microchondrule to three microchondrules found in two CM chondrites: Elephant Moraine (EET) 96029 and Murchison. In all instances, their formation appears closely linked to the late-stages of chondrule formation, chondrule recycling and fine-grained rim accretion. Likewise, they share cryptocrystalline textures and evidence of mild aqueous alteration and thus similar histories. We also investigate the host micrometeorite’s petrology, which includes an unusually Cr-rich mineralogy, containing both Mn-chromite spinel and low-Fe-Cr rich (LICE) anhydrous silicates. Because these two refractory phases cannot form together in a single geochemical reservoir under equilibrium condensation, this micrometeorite’s accretionary history requires a complex timeline with formation via non-equilibrium batch crystallization or accumulation of materials from large radial distances. In contrast, the bulk composition of this micrometeorite and its internal textures are consistent with a hydrated carbonaceous chondrite source. This micrometeorite is interpreted as a fragment of fine-grained rim material that once surrounded a larger parent chondrule and was derived from a primitive carbonaceous parent body; either a CM chondrite or Jupiter family comet.
Aerts J, van Spanning R, Flahaut J, et al., 2019, Microbial Communities in Sediments From Four Mildly Acidic EphemeralSalt Lakes in the Yilgarn Craton (Australia) – Terrestrial Analogs to Ancient Mars, Frontiers in Microbiology, ISSN: 1664-302X
Suttle M, Genge M, Folco L, et al., 2019, The atmospheric entry of fine-grained micrometeorites: the role of volatile gases in heating and fragmentation, Meteoritics and Planetary Science, Vol: 54, Pages: 503-520, ISSN: 1086-9379
The early stages of atmospheric entry are investigated in four large (250–950 μm) unmelted micrometeorites (three fine‐grained and one composite), derived from the Transantarctic Mountain micrometeorite collection. These particles have abundant, interconnected, secondary pore spaces which form branching channels and show evidence of enhanced heating along their channel walls. Additionally, a micrometeorite with a double‐walled igneous rim is described, suggesting that some particles undergo volume expansion during entry. This study provides new textural data which links together entry heating processes known to operate inside micrometeoroids, thereby generating a more comprehensive model of their petrographic evolution. Initially, flash heated micrometeorites develop a melt layer on their exterior; this igneous rim migrates inwards. Meanwhile, the particle core is heated by the decomposition of low‐temperature phases and by volatile gas release. Where the igneous rim acts as a seal, gas pressures rise, resulting in the formation of interconnected voids and higher particle porosities. Eventually, the igneous rim is breached and gas exchange with the atmosphere occurs. This mechanism replaces inefficient conductive rim‐to‐core thermal gradients with more efficient particle‐wide heating, driven by convective gas flow. Interconnected voids also increase the likelihood of particle fragmentation during entry and, may therefore explain the rarity of large fine‐grained micrometeorites among collections.
Suttle MD, Folco L, Genge MJ, et al., 2019, Intense aqueous alteration on C-type asteroids: Perspectives from giant fine-grained micrometeorites, GEOCHIMICA ET COSMOCHIMICA ACTA, Vol: 245, Pages: 352-373, ISSN: 0016-7037
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