PRL PLATINUM PLANETARY SEMINAR SERIES - PPPSS
Title : Volcanism, crustal cooling and impact history of the differentiated asteroid Vesta through the lens of the 40Ar/39Ar technique
Date : 18-08-2022
Time : 14:30:00
Speaker :
Prof. Fred Jourdan, Head of Discipline: Geology, Director of the Western Australian Argon Isotope Facility, School of Earth and Planetary Sciences, Curtin University, Perth WA6845
Venue : Online
Abstract
Based on 40Ar/39Ar analyses of different components (mineral, matrix, melt) of HED meteorites, the history of volcanism, crustal cooling and impact history will be elucidated.
Title : The Impact of Impact
Date : 04-08-2022
Time : 15:30:00
Speaker :
Prof. Dr. Philippe Claeys, Head of the Analytical, Environmental and Geochemical Research Group, VUB, Brussel
Venue : Online
Abstract
This presentation covers the identification of evidence to support a large meteorite impact at the Cretaceous-Paleocene boundary (K-Pg) 66 million years and the discovery and recent drilling of the Chicxulub crater in Yucatan. It also discusses how this major planetary collision triggered a rapid and brutal global environmental change that led to the demise of the non-avian dinosaurs and fauna and flora on Earth.
Title : Infrared Spectroscopy for the BepiColombo Mission to Mercury
Date : 28-07-2022
Time : 14:30:00
Speaker :
Dr. Andreas Morlok , niversity of Münster, Institut für Planetologie, Münster
Venue : Online
Abstract
Mercury, the innermost planet of the Solar System, is characterized by a heavily cratered surface, a lare core and a strong magnetic field. It was rarely visited by space probes, the ESA/JAXA mission to Mercury arriving in 2025 is only the third visit so far. Onboard is a suite of instruments allowing to investigate Mercury in high detail. This talk will focus on the MERTIS instrument. MERTIS (Mercury Radiometer and Thermal Infrared Spectrometer) will allow to map most of the hermean surface in the mid-infrared, a spectral region so far not covered in earlier missions. With the help of the expected data, the surface composition and mineralogy of Mercury will be determined in detail for the first time. The presentation will be about our work at the IRIS laboratory in Münster, where we conduct laboratory measurements for the interpretation of the expected result.
Title : A Time-Line for the Formation of Terrestrial Planets
Date : 07-07-2022
Time : 15:30:00
Speaker :
Prof. Klaus Mezger, Institute of Geological Sciences and Center for Space and Habitability, University of Bern, Switzerland
Venue : Online
Abstract
Chemical and isotopic analyses of primitive meteorites reveal that the building blocks of the rocky planets in our solar system are derived from different nucleosynthetic sources. These diverse materials were mixed at an early stage and provided the matter that ended up in the solar system bodies. The path from a gas-dust cloud to the final arrangement of the planets in our solar system took several 10s of million years and involved different processes, including condensation and evaporation, melting, collision and differentiation of planetesimals, impacts and metamorphism. A specific, and possibly unique, sequence of events and processes led to the formation of the Earth, the only known planet that brought forth life and sustained it for billions of years. Information on the early evolution of the solar system is stored in meteorites and their components and also can be reconstructed from the bulk composition of planets, particularly the Earth. A key piece of information for a good understanding of the dynamic evolution of our own planetary system is the timing of different physical and chemical processes and events in the early solar system. To this end geochronological information from meteorites needs to be combined with their chemical and isotopic composition.
Title : Tin stable isotope variations in natural materials: Implications for planetary and nebular processes
Date : 30-06-2022
Time : 14:30:00
Speaker :
Dr. Dipankar Pathak, Isotopengeologie Gruppe, Institut für Geologie, Universität Bern, Bern, Switzerland
Venue : Online
Abstract
The mass dependent isotope variation in volatile elements could act as useful proxies to understand the early solar system conditions, where materials processed through evaporation and condensation in the solar nebula was eventually incorporated by planetesimals during their accretion. The isotope composition of H and O, in a water molecule are subjected to modification during such physico-chemical processes, and hence it is difficult to readily extract information from them with less uncertainty. Tin being a moderately volatile element could be used to trace the origin of volatile components in a terrestrial planet like Earth. Due to a unique geochemical behavior of being both chalcophile and siderophile, Sn also additionally enables understanding the core formation process of Earth using iron meteorites and high P-T experimental products, as proxies. A novel wet chemistry based methodology was developed to provide these answers by precisely measuring stable Sn isotope variations in terrestrial and meteorite samples using a double spike MC-ICP-MS technique. Given the significance of such volatile elements, I will present the challenges in developing analytical methods for measuring Sn isotopes, and some results obtained from analyses of few terrestrial and chondrite samples.
Title : Primordial noble gas component hosted by water-susceptible materials in less-altered CR chondrites
Date : 16-06-2022
Time : 14:30:00
Speaker :
Dr. Tomoya Obase, Hokkaido University, Japan.
Venue : Online
Abstract
Previous studies of noble gases in primitive meteorites have focused primarily on acid-resistant phases that contain most of the noble gases in the primitive meteorites. However, a new Ne-rich noble gas component hosted by water-susceptible materials was recently found in some aqueously less-altered CR chondrites. In this seminar, I will talk about the potential relationship between the Ne-rich materials in CR chondrites and cometary materials. The talk also briefly introduces basic knowledge of noble gases in primitive meteorites and why noble gases are unique tracers in cosmochemistry.
Title : How hot and wet is the Moon: Insight from experiments
Date : 02-06-2022
Time : 10:00:00
Speaker :
Dr. Ananya Mallik, Assistant Professor, (The RealReal Inc. Endowed Chair in Gem Science), Department of Geosciences, University of Arizona, Tucson, Arizona, USA
Venue : Online
Abstract
The thermal profile of the Moon (selenotherm) is required to determine its present-day interior structure and composition, and yet it is not constrained well. How can we constrain the selenotherm better? Also, measurements on lunar samples indicate that the Moon is not ‘bone dry’ but does have some hydrogen in its interior. The bulk lunar hydrogen is an important constraint to understand the dynamics of the Moon-forming impact as well as determine the origin of volatiles in the Earth-Moon system. The estimates of bulk lunar hydrogen span across a few orders of magnitude, but how can we constrain it better? In this talk, I will discuss how we can better estimate both the thermal state and the bulk lunar hydrogen to improve our understanding of lunar evolution.
Title : The Terrestrial Impact Record
Date : 26-05-2022
Time : 15:30:00
Speaker :
Prof. Christian Koeberl, University of Vienna, Austria, Austrian Academy of Sciences
Venue : Online
Abstract
The recognition of impact craters on the Earth is difficult, because active geological and atmospheric processes on our planet obscure or erase the impact record in geologically short time periods. For the confirmation of impact craters on Earth, detailed mineralogical, petrographic, and geochemical studies are needed. Nevertheless, about 200 terrestrial impact craters have been identified. On Earth, the first impact evidence exists in the form of various spherule layers in South Africa and Australia, aged between about 3.4 and 2.5 Ga. The oldest preserved impact structures have ages of 2.02 and 1.86 Ga. Thus, there is little information about the impact record and its effects during the first 2.5 billion years of Earth history, but it is clear that then and later, impacts had severe effects on the geological and biological evolution on Earth.
Title : Mars - A short history through time
Date : 19-05-2022
Time : 16:30:00
Speaker :
Dr. Stephanie C. Werner, Professor of Geophysics and Planetary Sciences, Centre for Earth Evolution and Dynamics, Department of Geosciences, University of Oslo
Venue : Online
Abstract
The presentation will introduce the main geological processes acting on Mars, which are typical and common on Earth-like planets. Furthermore, it will provide insight into the geological evolution of Mars based on remote-sensing data. Using meteorites from Mars, one can extract detailed information on the rocks and minerals, as well as temporal constraints. Globally, sequencing of events relies on crater statistics. While Mars now appears to be rather a cold desert, in the past water has been more abundant. This is evident in martian morphology and mineralogy. Exploration of Mars with the help of spectral analyses indicate surface weathering and mineral formation that requires water. The different atmosphere composition, however, challenges simple transfer of process details from Earth to Mars. Nevertheless, Earth rocks and terrestrial analogue studies and experiments improve understanding Mars' evolutionary history.
Title : Aqueous alteration of primitive meteorites
Date : 12-05-2022
Time : 14:30:00
Speaker :
Dr. Wataru Fujiya, Associate Professor, Faculty of Science, Ibaraki University, Japan
Venue : Online
Abstract
Evidence for aqueous alteration can be found in essentially all chondrite groups and is pronounced in CI, CM, and CR chondrites. The aqueous alteration played an important roll in material evolution on water-rich planetesimals and thus an understanding of water activity is crucial to investigate how volatile materials including ice and organic matter were modified from their original forms in planetesimals before their delivery to terrestrial planets. In this seminar, I am talking about pristine materials in chondrites and how they were transformed by aqueous alteration in their parent bodies. I am focusing on the timing and the conditions such as temperature and water to rock ratios of the aqueous alteration. I will also raise a few unsolved questions about aqueous alteration for future research directions.
Title : Thermal alteration of CM chondrites: Mineralogical changes and metamorphic temperature
Date : 05-05-2022
Time : 14:30:00
Speaker :
Dr. Ashley King, Future Leader Fellow,UK Research and Innovation, Department of Earth Sciences, Natural History Museum, UK
Venue : Online
Abstract
Most CM chondrites experienced only low temperature (<300C) aqueous alteration in the early solar system. However, a number also record an episode of post-hydration thermal metamorphism at temperatures up to 1000C. Remote observations suggest that such materials may be common on the surface of primitive asteroids. We are therefore investigating the mechanism, timing, and duration of metamorphism in CM chondrites to better understand the thermal history of volatile-rich asteroids and provide context for samples returned from Ryugu and Bennu by the Hayabusa2 and OSIRIS-REx missions.
Title : Understanding Planetary Differentiation from Hf-W systematics
Date : 21-04-2022
Time : 14:30:00
Speaker :
Dr. G. Srinivasan, Bhopal
Venue : Online
Abstract
The source of one of the largest group of differentiated planets (asteroid 4 Vesta) is a differentiated planet with a metallic core. Meteorites from this asteroid collectively referred to by acronym HEDs (howardite, eucrite, and diogenites) provide a valuable avenue for studying evolution of rocky terrestrial planets. These small rocky bodies arrested in different stages of evolution, preserve information about processes that have been erased on larger planets due to their prolonged activity. Differentiated silicate rich meteorites are depleted siderophile elements while Fe meteorites are rich rich in these elements. The homogeneous oxygen isotope composition support large scale melting event on the planetary body resulting in a metallic core and a silicate mantle, very much like Earth, Moon and Mars. I will explore the elemental distribution of W in these silicate rich meteorites and 182Hf-182W isotope systematics to constrain the process of planetary differentiation.
Title : The Ancient Climate of Mars: Was the Ambient Climate 'Warm and Wet' or 'Cold and Icy'?
Date : 07-04-2022
Time : 15:00:00
Speaker :
Dr. Jim Head, Professor of Earth, Environmental, and Planetary Sciences (Research), Brown University
Venue : Online
Abstract
One of the most fundamental questions in planetary science today is the nature of the ambient climate of early Mars (Noachian-Early Hesperian): Was the ambient climate “warm and wet”, as suggested by widespread phyllosilicates, higher erosion rates, enhanced crater degradation, valley networks, and open/closed-basin lakes? Or was the ambient climate “cold and icy”, as suggested by recent climate models, with occasional perturbations causing heating and melting of surface snow and ice, and runoff to produce the observed characteristics and features? Using the framework of these two ambient climate options, we will discuss outstanding questions and how these might be resolved. We will also explore the roles of the NASA Mars 2020 mission to the Jezero Crater open-basin lake, and the CNSA Tianwen-1 mission to Utopia Planitia in addressing these issues.
Title : Meteorites from Morocco: An overview
Date : 01-04-2022
Time : 15:30:00
Speaker :
Prof. Hasnaa CHENNAOUI AOUDJEHANE, Faculty of Sciences Ain Chock FSAC, Department of Geology, Casablanca MOROCCO
Venue : Online
Abstract
An overview of meteorites from Morocco will be given in this talk. Meteorites are extraterrestrial rocks. They are crucial not only to the apparition of water and life on Earth but also to the mass extinction of species. Meteorites are mostly found in cold deserts such as Antarctica and hot ones such as Oman, Sahara and Chili. The Sahara, and especially the Moroccan one, provides a significant number of meteorites for researchers and collectors all over the world.
Title : Hands-on Astrophysics: Analysis of Presolar Stardust Grains to Decipher Stellar Nucleosynthesis
Date : 10-03-2022
Time : 09:30:00
Speaker :
Dr. Reto Trappitsch, Brandeis University, Waltham, MA, USA.
Venue : Online
Abstract
The talk introduces how analyses of presolar stardust grains allow us to decipher the slow neutron-capture (s-) process in asymptotic giant branch stars. These measurements are therefore valuable to better understand how the material the Solar System formed from came together in the first place. The talk also introduces resonance ionization mass spectrometry (RIMS), a technique that allows us to analyze the trace element isotopic composition in such micrometer-sized samples. Finally, the background of stellar nucleosynthesis and existing measurements to constrain the s-process are discussed before concluding with an outlook to future RIMS measurements.
Title : Condensation and Radial Transport of Filamentary Enstatite Crystals from Interplanetary Dust
Date : 03-03-2022
Time : 09:30:00
Speaker :
Prof. Ryan Ogliore, Washington University, St. Louis, U. S. A.
Venue : Online
Abstract
Filamentary enstatite crystals, formed by gas-solid condensation in the solar nebula, are found in chondritic porous interplanetary dust particles of probable cometary origin. We measured the oxygen isotopic composition of five filamentary enstatite grains from the giant cluster interplanetary dust particle U2-20 GCP. These grains sample both the 16O-rich solar (∆17O ≈ −30 per mil) and 16O-poor planetary (∆17O ≈ 0 per mil) isotope reservoirs. Our measurements provide evidence for very early vaporization of dust-poor and dust-rich regions of the solar nebula, followed by condensation and outward transport of crystalline dust to the comet-forming region very far from the Sun. Similar processes are likely responsible for the crystalline silicates observed in the outer regions of protoplanetary disks elsewhere in the Galaxy.
Title : Atomic-Scale Structure and Non-Stoichiometry of Meteoritic Hibonite
Date : 24-02-2022
Time : 09:30:00
Speaker :
Dr. Jangmi Han, University of Houston, U. S. A.
Venue : Online
Abstract
Hibonite (CaAl12O19) is a common refractory mineral in Ca-Al-rich inclusions (CAIs) in primitive meteorites and provides crucial insights into the conditions and processes that existed in the early solar nebula. Transmission electron microscope (TEM) studies have identified enigmatic planar defects in different occurrences of hibonite in the Allende meteorite. Atomic resolution high-angle annular dark-field (HAADF) imaging and energy dispersive X-ray (EDX) analyses were used to determine the nature and origin of these planar features. Our TEM analyses revealed that the modification of the stacking sequence in hibonite and its non-stoichiometry (i.e., Al and Mg excesses) likely played a major role in the formation and metastability of planar defects in hibonite. The formation history of planar defects in hibonite will be discussed to provide implications on the formation conditions for refractory first solids in the early and high-temperature evolution stage of our Solar System.
Title : Volatiles on Mars - from meteorites to sample return
Date : 10-02-2022
Time : 14:30:00
Speaker :
Dr Susanne P. Schwenzer, Associate Director Astrobiology OU School of Environment, Earth and Ecosystem Sciences, The Open University, Milton Keynes, U. K.
Venue : Online
Abstract
Volatiles on Mars come in two categories: those, which react or are reaction products, and those which are inert. The latter are the noble gases, which can record processes such as degassing or atmospheric loss without taking part in any reactions that might also happen. In the Martian meteorites they present a complex story that to this day has conundrums to offer – but maybe, just maybe we are getting an atmospheric sample with the first ever sample return mission that would allow us to solve a few of the open questions. Of the volatiles that react or are products of reaction, methane captures our imagination most, because it is enigmatic in its sporadic occurrence, and it could, maybe, if Earth is a good proxy, with all the hedging that language has to offer, be linked to life. But of course, we do not know that. What we know is that water has a long history on Mars, carved channels, and most importantly for this part of the story, altered minerals. This talk will present a personal journey of 25 years of research into the sources, pathways, reactions and sinks of noble gases, methane and water. Thus, the selection is biased, and very much guided by the speaker’s own excitement about topics such as the Kr/Xe ratio in the nakhlite Martian meteorites and the water rock reactions that form carbonates on Mars.
Title : Condensation and Radial Transport of Filamentary Enstatite Crystals from Interplanetary Dust
Date : 03-02-2022
Time : 09:30:00
Speaker :
Prof. Ryan Ogliore, Washington University, St. Louis, U. S. A.
Venue : Online
Abstract
Filamentary enstatite crystals, formed by gas-solid condensation in the solar nebula, are found in chondritic porous interplanetary dust particles of probable cometary origin. We measured the oxygen isotopic composition of five filamentary enstatite grains from the giant cluster interplanetary dust particle U2-20 GCP. These grains sample both the 16O-rich solar (∆17O ≈ −30 per mil) and 16O-poor planetary (∆17O ≈ 0 per mil) isotope reservoirs. Our measurements provide evidence for very early vaporization of dust-poor and dust-rich regions of the solar nebula, followed by condensation and outward transport of crystalline dust to the comet-forming region very far from the Sun. Similar processes are likely responsible for the crystalline silicates observed in the outer regions of protoplanetary disks elsewhere in the Galaxy.
Title : Chondrule formation: A controversial issue among different models
Date : 27-01-2022
Time : 16:00:00
Speaker :
Dr. Maria Eugenia Varela, ICATE-CONICET, San Juan, Argentina
Venue : Online
Abstract
Chondrites are the most primitive meteorites that preserve useful information about the time the Solar System formed, about 4.56 Ga ago. One of their major constituents are chondrules, μm to mm sized spherical objects which constitute up to 80% of the volume of the most primitive meteorites and are composed mainly of ferromagnesian silicates. The process/es involved in chondrule formation cover a wide range of mechanisms whose nature is still unknown. I will discuss the two principal models that are outlined concerning the origin of chondrules in the solar nebula. There is no real consensus regarding the nature of the initial liquid droplets from which chondrules are supposed to be formed, nor about the different processes that were active during and after chondrule formation. An alternative model: the Primary Liquid Condensation (PLC) model can explain the growth of single crystals through a process in which liquid condenses first and then nucleates a crystal of the species that is oversaturated in the vapor. This process refers to a vapor-liquid-solid growth process that take place in equilibrium with a chondritic reservoir. Finally, I will inform of the first glass inclusion hosted in spinel within a glass-rich chondrule from the unequilibrated ordinary chondrite Catalina 278 (LL3.4). A possible sample of the initial liquid trapped during spinel growth.
Title : Origin and evolution of nitrogen on planetary bodies in the inner solar system
Date : 20-01-2022
Time : 14:30:00
Speaker :
Dr. Evelyn Füri, Centre de Recherches Pétrographiques et Géochimiques (CRPG, CNRS-UL), France
Venue : Online
Abstract
Knowledge of the origin of nitrogen on Earth is of particular importance to understanding the development of conditions favorable to the emergence of prebiotic molecules and the maintenance of life on rocky planets. However, the origin and timing of the accretion of nitrogen on Earth remains a subject of controversy. In this talk, I will present new data obtained by secondary ion mass spectrometry (SIMS) analyses of extraterrestrial melt inclusions. First, I will show that olivine-hosted melt inclusions in angrites and martian meteorites are key for constraining the source(s) and timing of nitrogen delivery to planetary bodies in the inner solar system. However, the effects of planetary formation processes (core formation, magma ocean crystallization and degassing) on the original elemental and isotopic composition of planetary mantles still need to be investigated.
Title : How well can we link meteorites to asteroids
Date : 13-01-2022
Time : 09:30:00
Speaker :
Prof. Thomas Burbine , Department of Astronomy, Mount Holyoke College, USA
Venue : Online
Abstract
Asteroids are the remaining planetesimals that helped form the terrestrial and Jovian planets. Asteroids, which are the parent bodies of almost all meteorites, are almost entirely observed remotely using Earth- and space-based telescopes with only a few bodies studied up close by spacecraft missions. The chemical and isotopic compositions of meteorites can be determined with high precision in laboratories on Earth; however, remote observations of asteroids give geochemical information. In this seminar asteroid-meteorite relationship will be discussed.
Title : Nucleosynthetic heterogeneity in the early solar system: insights from Nd isotopes
Date : 06-01-2022
Time : 15:30:00
Speaker :
Dr. Nikitha Susan Saji, Centre for Star and Planet Formation, Globe Institute, University of Copenhagen, Denmark
Venue : Online
Abstract
Isotopic variability from heterogeneous distribution of presolar dust in the solar protoplanetary disk is now well-established for a number of elements. Yet, significant uncertainty exists regarding the inventory of presolar dust populations that were initially present in the protosolar molecular cloud and their eventual aggregation into planets and planetesimals. In this talk, I will review what high precision Nd isotope measurements of meteorites and their components tell us about the diversity of nucleosynthetic components that contributed material to the nascent solar system and how they resulted in an apparent bifurcation of solar system materials into carbonaceous and non-carbonaceous suites.
Title : Chondrites and the early solar system
Date : 30-12-2021
Time : 16:30:00
Speaker :
Dr. Yogita Kadlag, NCCR PlanetS advanced Post-Doctoral fellow, Universität Bern, Switzerland
Venue : Google meet
Abstract
Precursors of all solar system objects such as meteoroids, asteroids, comets, proto-planets, and planetary satellites were formed through physical and chemical processing (e.g. condensation-evaporation, variable heating, mixing, etc.) of nebular dust and gas of about 0.1% solar mass. To understand the role of initial chemical and isotopic heterogeneity and subsequent physicochemical processing of dust, gas and planetary precursors in the solar nebula, chemical and isotopic variations in the components of undifferentiated meteorites such as calcium-aluminum-rich inclusions, chondrules, matrix and Fe-Ni metal can be used as tracers. Here, I discuss examples of chondrules and separated components from unequilibrated chondrites to explore the origin of isotopic heterogeneities and processing of mm to cm scale objects within the first few million years of the solar system evolution.
Title : First Formed Solids: Records of the Earliest Times of the Solar System
Date : 23-12-2021
Time : 10:30:00
Speaker :
Dr. Prajkta Mane , Visiting Scientist, Lunar and Planetary Institute (USRA), Astromaterials Research and Exploration Science Division, NASA Johnson Space Center, Houston TX 77058
Venue : Google meet
Abstract
Meteorites and their components can be used to unravel the history of the early Solar System. Carbonaceous chondrites are meteorites that originated from undifferentiated parent bodies that formed within a few million years of the beginning of the Solar System. These meteorites contain calcium-aluminum-rich inclusions (CAIs), which are the oldest dated solids forming in our Solar System at ~4.567 billion years old and thus preserve a record of the earliest stage of Solar System formation. The radiometric dating of these CAIs and other meteoritic components provides important time constraints on the events that occurred in the early Solar System, whereas textures and microstructures in these CAIs preserve the evidence of disk processes in them. In this talk, I will discuss the results of a coordinated multi-technique approach to analyzing CAIs and their components to reveal the timescales and conditions of their formation.
Title : Isotopic constraints on the conditions of chondrule formation in carbonaceous chondrites
Date : 16-12-2021
Time : 14:00:00
Speaker :
Prof. Yves Marrocchi, Research Director at CNRS, Deputy Director of the CRPG, France
Venue : Google meet
Abstract
In this talk, I will review the recent measurements carried out on chondrules of carbonaceous chondrites for different isotopic systems (O, Si, Cr, Ti). I will use these data to discuss the different models of chondrule formation in the framework of both planetary and nebular scenarios.
Title : The Origins of Organic Matter and Amorphous Silicates in Meteorites – Clues from Nanoscale Investigations
Date : 09-12-2021
Time : 14:30:00
Speaker :
Prof. Christian Vollmer, Institut für Mineralogie, WWU Münster, Germany
Venue : Google meet
Abstract
Pristine carbonaceous chondrites provide important samples of the very early solar nebula. These complex rocks recorded snapshots of events 4.56 Ga years ago that can be disentangled by advanced analytical techniques on Earth. One of the most challenging components to analyze within such chondrites is the so-called “matrix”, a fine-grained mixture of presolar dust, amorphous and crystalline silicates, organic matter, sulfides, and metal, in which larger constituents such as chondrules or refractory inclusions are embedded. Organic matter (OM) and amorphous silicates within chondrite matrix are specifically important, because they record crucial condensation and synthesis processes in the solar nebula and meteorite parent bodies, but are also prone to alteration and destruction. In this talk, I want to summarize recent work by high-spatial resolution analysis techniques (TEM, UltraSTEM, NanoSIMS) on amorphous silicates and organic matter in a variety of pristine carbonaceous chondrites. We analyzed the functional chemistry signatures of these unique materials by electron energy loss spectroscopy (EELS) and synchrotron X-ray spectroscopy methods (STXM) to disentangle complex formation pathways. Organic matter records very early biomolecule reaction pathways, whereas the chemical composition and Fe oxidation state of amorphous silicates within matrix regions can be analyzed to understand early solar nebula condensation and alteration processes.
Title : Sulfur isotope anomalies in Acfer 094 inherited from the Irradiation of the Protosolar Molecular Cloud by Massive Nearby Stars.
Date : 30-11-2021
Time : 18:00:00
Speaker :
Dr. Lionel Vacher, Washington University St. Louis, USA
Venue : Online
Abstract
Spectral line (121.6 nm) and larger or smaller wavelengths produce MI anomalies that define distinct ∆36S/∆33S ratios. Young stars have strong emission at Lyman-alpha, while massive O and B stars dominate the interstellar UV flux. Thus, the photodissociation of H2S can serve to differentiate between massive stars and young T-Tauri stars as the astronomical source of isotope-selective photodissociation. Analysis of paired oxygen and sulfur isotope systematics in cosmic symplectite (COS)−a nm-scale intergrowth of 16O-poor magnetite and pentlandite−in the primitive carbonaceous chondrite Acfer 094 can provide unique insights into photochemical processing of Solar System materials. Acfer 094 shows similarities to cometary material and, therefore, may have formed in the outer Solar System where it could have incorporated 16O-poor water ice that also contained H2S ice like that detected in comets. Sulfur in COS may provide insights into the astrophysical environment for the Solar System formation. In this talk, I'll report the oxygen and sulfur isotopic composition of COS and determine the likely astrophysical UV source responsible for photochemical processing of Solar System solids.
Title : Serpentinization of iron-rich olivine and its potential for abiotic methane synthesis in planetary bodies
Date : 25-11-2021
Time : 14:30:00
Speaker :
Dr. Alik Sundar Majumdar, Department of Applied Geology Indian Institute of Technology (Indian School of Mines) Dhanbad Jharkhand, India
Venue : https://meet.google.com/fns-cpjv-snn
Abstract
Serpentinization of olivine-rich ultramafic rocks are increasingly recognized to have been widespread in the solar system throughout its history. This process has gained particular attention among planetary scientists because it generates molecular hydrogen (H2) and methane (CH4), compounds that can supply metabolic energy to biological communities and contribute to greenhouse warming of planetary atmospheres. Following this, the talk will demonstrate a series of natural (meteorites) and experimental observations as well as thermodynamic models to show the pattern of secondary mineral formation and H2 generation during serpentinization of olivine as a function of Fe content and temperature. It will also be shown that serpentinization of Fe-rich olivine can generate substantially greater amounts of H2 per mole than is observed for serpentinization of Mg-rich olivine, depending on the magnitude of Fe (III) partitioning into serpentine phase. Thus, serpentinization on planetary bodies may have a greater potential to supply H2 vis-à-vis CH4 to support biological communities and enhance the atmospheric greenhouse warming than analogous processes on Earth.
Title : Constraining thermal processing of dust grains in space and on the surface of airless bodies through in-situ laboratory experiments
Date : 18-11-2021
Time : 09:30:00
Speaker :
Dr. Pierre Haenecour, Lunar and Planetary Laboratory, The University of Arizona, Tucson, USA
Venue : Online
Abstract
Fine-grained material in chondritic meteorites typically consists of a mixture of crystalline and amorphous silicates, oxides, sulfides, Fe-Ni metal grains, and carbonaceous matter that accreted together from the solar protoplanetary disk. Some of these ‘primary’ phases were affected by secondary processing, including both heating and aqueous alteration, on their host asteroid. The response of these materials to secondary alteration is important for understanding active processes on the surfaces and within the chondrite-parent asteroids. Thermal metamorphism, in particular, could have played an important role in processes such as melting, volatile loss, elemental diffusion between grains, and driving hydrothermal processing. In my talk, I will discuss how we are using in-situ heating experiments inside electron microscopes to better understand the effect(s) of heating on the composition and microstructure of fine-grained materials.
Title : Heterogeneous accretion of volatiles to Earth's mantle reservoirs
Date : 12-11-2021
Time : 18:00:00
Speaker :
Dr. Rita Parai, Washington University, U. S. A.
Venue : Online
Abstract
Earth’s interior retains volatiles (e.g., nitrogen, carbon, hydrogen and the noble gases) acquired during accretion. Solar, chondritic and cometary noble gases may all have contributed to terrestrial volatile reservoirs. This study shows that helium (He), neon (Ne) and xenon (Xe) isotopes of the upper mantle and the plume mantle source can only be explained if the latter reservoir had a low initial Xe abundance. A record of limited accretion of volatile-rich chondrites into the deep mantle compared to the upper mantle thus survives in the He-Ne-Xe signatures of mantle rocks today. Energetic impacts during accretion did not homogenize the growing planet, and early-formed 129Xe and 182W mantle heterogeneities may have survived through ~4.5 Gyr of mantle mixing due to a viscosity contrast originating from differential accreted water contents in the plume and upper mantle reservoirs.
Title : Entering an Unseen World: Biology vs. Science – Who sees further?
Date : 28-10-2021
Time : 18:00:00
Speaker :
Dr. Frank Gyngard, Harvard, USA
Venue : Online
Abstract
Over the last many decades, there has been an undeniable advance in our ability to see into materials at the micro and nano scale, that not even the highest-powered optical microscope could reveal. >From meteorites to cells, this revolution has revealed to us the substructures and wonders of natural phenomena. This talk will focus on the parallels of applying NanoSIMS techniques to both biology and cosmochemistry/presolar grains. It will also give some general advice gleaned from the world of biology, in terms of grants, publications, and general outlook for future NanoSIMS studies. And for fun, you will also see the Chicago car tow lot!
Title : Nascent Sun & repetitive Super flares
Date : 21-10-2021
Time : 18:00:00
Speaker :
Dr. Ritesh Mishra, Application Engineer, Cameca, India
Venue : Online
Abstract
The chronology of the early Solar system events during the first few millions years are presently constrained at a few 100 ka which is a few orders of magnitude larger than the typical time scale of a few 100-1000 years of evaporation, condensation, cooling, solar flaring events (FUor) etc.. Evidence of such a high resolution temporal record of a superflare from the young Sun during its birth inferred from fossil records of 7Be, 10Be will be presented in the talk.
Title : Minor and trace element concentrations in adjacent kamacite and taenite in the Krymka chondrite
Date : 14-10-2021
Time : 14:30:00
Speaker :
Dr. Smail Mostefaoui, Paris, France
Venue : Online
Abstract
We report NanoSIMS in situ siderophile minor and trace element abundances in individual Fe-Ni metal grains in the unequilibrated chondrite Krymka (LL3.2). Associated kamacite and taenite of 10 metal grains in four chondrules and one matrix metal were analyzed for elemental concentrations of Fe, Ni, Co, Cu, Rh, Ir, and Pt. The results show large elemental variations among the metal grains. However, complementary and correlative variations exist between adjacent kamacite-taenite. This is consistent with the unequilibrated character of the chondrite and corroborates an attainment of chemical equilibrium between the metal phases. The calculated equilibrium temperature is 446 ± 9 °C. This is concordant with the range given in literature for the Krymka post-accretion thermal metamorphism. Based on Ni diffusivity in taenite, a slow cooling rate is estimated of the Krymka parent body that does not exceed ~1K Myr-1, which is consistent with cooling rates inferred by other workers for unequilibrated ordinary chondrites. Elemental ionic radii might have played a role in controlling elemental partitioning between kamacite and taenite. The bulk compositions of the Krymka metal grains have nonsolar (mostly subsolar) element/Ni ratios suggesting the Fe-Ni grains could have formed from distinct precursors of nonsolar compositions or had their compositions modified subsequent to chondrule formation events.
Title : Isotopic and elemental studies of presolar graphite grains and what they tell us about their parent stars
Date : 06-10-2021
Time : 18:00:00
Speaker :
Dr. Manavi Jhadav, University of Louisiana, USA
Venue : Online
Abstract
The laboratory study of stardust or presolar grains is an important sub-field of astrophysics. It combines sophisticated chemical, structural, and isotopic laboratory measurements, on micron-sub-micron presolar particles, with the theoretical ideas of nucleosynthesis and stellar evolution that exist to understand astrophysical observations. Isotopic data for these grains reveal more precise information about their parent stars than do spectroscopic observations of circumstellar dust. The goal of laboratory measurements is to provide clues on the stellar environments in which the grains formed and on their subsequent histories. Additionally, investigations into the preservation of these grains in different meteorites provide information about early solar system conditions and chronology. These goals can be achieved by coordinated, multi-technique investigations of presolar grains in the laboratory. This talk will focus on results from coordinated, multi-technique measurements of presolar graphite grains and what they tell us about the stars that contributed presolar materials to our nascent Solar System.
Title : 26Al in AGB grains.
Date : 23-09-2021
Time : 19:00:00
Speaker :
Dr. Nan Liu, Washington University St. Louis, USA
Venue : Online
Abstract
Presolar grains found in pristine meteorites are stellar relics that predate our solar system. They enable the study of bonafide stellar materials in the laboratory, where the full battery of modern micro-analytical techniques can be brought to bear on them. In this talk, I will present new NanoSIMS isotopic data of presolar SiC grains and discuss their stellar origins and 26Al production in low-mass stars in the light of astronomical observations for carbon stars and stellar models.
Title : Shock-induced incongruent melting of olivine and formation of natural Fe-bearing aluminous bridgmanite in ordinary chondrites.
Date : 16-09-2021
Time : 16:00:00
Speaker :
Prof. Sujoy Ghosh, IIT Kanpur
Venue : Online
Abstract
The planet Earth was formed from a similar material that constitutes present-day asteroids. Olivine and bridgmanite are the most volumetrically abundant mineral of the Earth’s upper and lower mantle, and it is important to understand its formation mechanism to better comprehend the origin and evolution of planetary interiors. Olivine breaks down to bridgmanite and magnesiowüstite formed by the solid-state or melting of the olivine. Whereas, natural bridgmanites have been reported in only a few shocked meteorites; however, the composition of these specimens differs from plausible compositions of terrestrial bridgmanite. In this presentation, I will present our recent results which show the possible occurrence of bridgmanite and magnesiowüstite formed by incongruent melting of olivine in an ordinary chondrite (Kamargaon L6 chondrite) and the first natural occurrence of bridgmanite, observed in an ordinary chondrite, with a composition closest to the bridgmanite present in the Earth’s lower mantle. The bridgmanite in the ordinary chondrite (Katol L6 chondrite) has high Fe3+/Fe ratio and agrees with experimental predictions. The Katol chondrite may serve as a unique analogue for crystallization of bridgmanite during the final stages of magma ocean crystallization of the Earth.
Title : Micrometeorites on the Earth surface: Understanding their origin and properties.
Date : 02-09-2021
Time : 14:30:00
Speaker :
Dr N G Rudraswami, National Institute of Oceanography (NIO) Goa
Venue : Online
Abstract
Throughout its history planet Earth has been continuously bombarded by high-speed extraterrestrial material. These are debris of comets and asteroids that are leftover material in the solar system, but additional sources may occasionally contribute. The Earth surface accretes a complex variety of these extra-terrestrial material at a rate of approximately 40,000 tons per annum. The dominant size fraction of these extra-terrestrial materials are in the range of few ten of µm to few mm. These sub-mm size particles called as micrometeorites (MMs) provide us an unique opportunity to study diverse collection of samples of solar system bodies in the laboratory. Many micrometeorites have shown textural, chemical, isotopic and trace element composition that can be linked to primitive chondrites such as CI and CM chondrites. Some of these particles are not found in meteorite studies indicate existence of diverse type of precursors in the asteroidal belt that is still not in our inventory. Most dust-sized cosmic particles undergo ablation and chemical alteration during atmospheric entry due to rapid frictional heating, which alters their original properties depending on the size, composition, entry velocity and angle. A comprehensive understanding of this process is essential in order to decipher their pre-entry characteristics. My talk will focus on understanding their chemical and isotopic properties of micrometeorites, that can enhance our overall understanding of these objects.
Title : Organics on Itokawa asteroid via analyses of Hayabusa samples.
Date : 26-08-2021
Time : 18:00:00
Speaker :
Dr Queenie Chan, Royal Holloway, University of London, UK
Venue : Online
Abstract
Understanding the true nature of extra-terrestrial water and organic matter that were present at the birth of our solar system, and their subsequent evolution, necessitates the study of pristine astromaterials. Such investigation necessitates the availability of pristine samples of astromaterials—samples that have not been compromised by terrestrial contamination, and thus preserve the intrinsic states of the materials’ physical, chemical, organic and other properties In this connection, the Hayabusa mission of the Japan Aerospace Exploration Agency (JAXA) is the first asteroidal sample return mission, which has successfully recovered regolith particles from the near-Earth S-type asteroid 25143 Itokawa in 2010. The Hayabusa particles were linked to LL ordinary chondrites based on mineralogy, chemistry and oxygen isotope compositions. Investigation of mineralogy, water and organic contents and other results an Itokawa particle will be discussed.
Title : Origin of the solar system
Date : 12-08-2021
Time : 14:00:00
Speaker :
Prof. Sandeep Sahijpal, Punjab University
Venue : Online