Designed by Gen Kaneko


Depository of Reference for Earth and Analytical Materials

Designed by Gen Kaneko


Here are the highlights of research carried out at IPM and its samples and datasets are stored in DREAM.

A study of the Chelyabinsk meteorite

(left) CBK-39 dream/?q=20130711200759-519652 and (right) TS OK7m-a dream/?q=20130704180756-780204.

On the 15th February (2013), a meteorite impacted Chelyabinsk state in Russia. Because of damages to local people, it was reported as a natural incident on worldwide news. It is referred to as the Chelyabinsk meteorite and was categorized as an ordinary chondrite. It has a genetic relationship to the asteroid Itokawa, which is also composed from fragments of ordinary chondrite. Since Chelyabinsk was collected soon after the fall, the terrestrial modification is considered to be minimum and the sample is appropriate to understand the origin of the meteorite by applying systematic analyses. We have initiated the research to reveal the formation processes of asteroids, which are the source of meteorites.

The samples and datasets inferred in the manuscript are all accessible here (dream/?q=20190115102242-432018).

A study of samples returned by the Hayabusa spacecraft

In the sample return mission from S type asteroid Itokawa conducted for the first time in history, the Phesant Memorial Laboratory (PML) had played the role of the initial analysis of particles returned by Hayabusa Spacecraft Read More

Eizo Nakamura, Tak Kunihiro, Tsutomu Ota, Chie Sakaguchi, Ryoji Tanaka, Hiroshi Kitagawa, Katsura Kobayashi, Masahiro Yamanaka, Yuri Shimaki, Gray E. Bebout, Hitoshi Miura, Tetsuo Yamamoto, Vladimir Malkovets, Victor Grokhovsky, Olga Koroleva, and Konstantin Litasov (2019) Hypervelocity collision and water-rock interaction in space preserved in the Chelyabinsk ordinary chondrite, Proceedings of the Japan Academy, Series B, Volume 95, Issue 4, Pages 165-177.

A comprehensive geochemical study of the Chelyabinsk meteorite reveals further details regarding its history of impact-related fragmentation and melting, and later aqueous alteration, during its transit toward Earth. We confirmed an ∼30 Ma age for the impact-related melting, based on Rb-Sr dating of a melt domain. An irregularly shaped olivine with a distinct O isotope composition similar to R-chondrite, in a melt domain, appears to be a fragment of a silicate-rich impactor. Hydrogen and Li concentrations and isotopic compositions, textures of Fe oxyhydroxides, and the presence of organic materials located in fractures, are together consistent with aqueous alteration. Evaluation of H and Li isotope systematics suggests that the component of this alteration could have pre-dated interaction with the Earth’s atmosphere and surface reservoirs. As one model in which the alteration could reflect recent pre-terrestrial processes, we suggest that hypervelocity capture of the impact related debris by a comet nucleus could have led to shock-wave-induced supercritical aqueous fluids dissolving the silicate, metallic, and organic matter, with later ice sublimation yielding a rocky rubble pile sampled by the meteorite.

How a comet turns into a rubble pile asteroid (a) By collision, a pre-existing asteroid gets shocked, melted, and fragmented within the last 30 million years. A comet captures the fragments of rock. (b) Because of the relative velocity, the kinetic energy is turned into heat. On impact, ice turns into water and the rock fragment gets submerged in water. (c,d) Ice on the comet is sublimated by radial heat from the Sun. (e) At the end, only rock fragments, dust, and organic materials remain. They are weakly bound by gravity and the aggregate looks like a rubble pile asteroid. The Chelyabinsk meteorite should have been delivered from such small body on the current Solar system.

See visual analysis. See also visual analysis with extra datasets <20190326083025-844154> The samples and datasets inferred in the manuscript are all accessible here  (dream/?q=20120224095412-627-620).


The publications below are published through the recent research activities of IPM. Click the title of a paper, and you can find the information of samples that involved in the paper. It may take a while to display the information when many samples are involved in the paper.

Christian Potiszil, Ryoji Tanaka, Katsura Kobayashi, Tak Kunihiro, Eizo Nakamura (2020) The Albedo of Ryugu: Evidence for a High Organic Abundance, as Inferred from the Hayabusa2 Touchdown Maneuver, Astrobiology, 20

The Hayabusa2 mission successfully collected samples from the asteroid Ryugu last year and will return these to Earth in December 2020. It is anticipated that the samples will enable the analysis of terrestrially uncontaminated organic matter and minerals. Such analyses are in turn expected to elucidate the evolution of organic matter through Solar System history, including the origination and processing of biogenically important molecules, which could have been utilized by the first organisms on Earth. In anticipation, studies have made predictions concerning the properties of Ryugu, including its composition. The spectral characteristics of Ryugu, such as albedo, have been employed to relate the asteroid to members of the carbonaceous chondrite group that have been identified on Earth. However, the recent Hayabusa2 touchdown highlights a disparity between the color of surfaces of displaced platy fragments, indicating a brightening trend for the surface exposed to space compared to that facing into the body. Here we present a mass balance calculation with reference to data from the literature, which indicates that Ryugu may contain a significantly higher abundance of organic matter (likely >50%) than the currently most accepted meteorite analogues. A high organic content may result in high levels of extractable organic matter for the second touchdown site, where the spacecraft sampled freshly exposed material. However, high abundances of insoluble aromatic/graphitic rich organic matter may be present in the first touchdown site, which sampled the surface of Ryugu that had been exposed to space. Moreover, we suggest that the potentially high organic abundance and the rubble-pile nature of Ryugu may originate from the capture of rocky debris by a comet nucleus and subsequent water-organic-mineral interactions and sublimation of water ice.

Christian Potiszil, Ryoji Tanaka, Tsutomu Ota, Tak Kunihiro, Katsura Kobayashi, Eizo Nakamura (2020) Concentration of meteoritic free organic matter by fluid transport and adsorption, Geochemical Perspectives Letters, 13, 30-35.

Carbonaceous chondrites contain many abiotic organic compounds, some of which are found in life on Earth. Both the mineral and organic matter phases, of these meteorites, have been affected by aqueous alteration processes. Whilst organic matter is known to be associated with phyllosilicate phases, no such relationship has yet been identified for specific organic compound classes. Furthermore, ongoing sample return missions, Hyabusa 2 and OSIRIS-Rex, are set to return potentially organic rich C-type asteroid samples to the Earth. Consequently, strategies to investigate organic-mineral relationships are required. Here we report spatial data for free/soluble organic matter (FOM/SOM) components (akylimidazole and alkylpyridine homologues) and mineral phases. Low and intermediate molecular weight alkylimidazole homologues are more widely distributed than higher molecular weight members, likely due to their affinity for the aqueous phase. On aqueous alteration of anhydrous mineral phases, transported FOM is adsorbed onto the surface or into the interlayers of the resulting phyllosilicates and thus concentrated and protected from oxidising fluids. Therefore, aiding the delivery of biologically relevant molecules to earth, shortly preceding the origin of life.

Hajime Taniuchi, Takeshi Kuritani, Tetsuya Yokoyama, Eizo Nakamura, Mitsuhiro Nakagawa (2020) A new concept for the genesis of felsic magma: the separation of slab-derived supercritical liquid, Scientific Reports 10, 8698.

Felsic magmas produced at subduction zones have played an important role in the generation and evolution of the continental crust. For the origin of felsic magmas, processes such as fractional crystallization of mafic magmas, partial melting of crustal materials, partial melting of subducting slabs, and partial melting of pyroxenitic mantle wedge components have been proposed. Recent experimental studies have predicted that felsic melt can also be produced in the mantle wedge by the separation of slab-derived supercritical liquid beyond depths corresponding to the critical point. To date, however, the presence of felsic magma of this origin has not yet been reported. In this study, we investigated dacitic lavas and preceding calc-alkaline andesite lavas from the Rishiri Volcano, located at the rear of the Kuril arc. We show that hydrous felsic melt and aqueous fluid were separated from slab-derived supercritical liquid in the mantle wedge. The former erupted as dacitic magma whilst the aqueous fluid induced the generation of primary basaltic magma involved in creating calc-alkaline andesite magma. We infer that slab-derived supercritical liquid is an efficient transport medium for moving silicate-rich components from subducting slabs to the Earth’s surface, and that this process may have contributed to the growth of the continental crust.

Last modified: Thu Jan 1 12:00:00 UTC 1970