Petrology of Yamato-75261 meteorite: An enstatite (EH) chondrite breccia

Yamato-75261 is a breccia with a non-porphyritic clast embedded in the partly porphyritic matrix. The clast consists mainly of closely packed finegrained enstatite with interstitial material rich in Al. Metallic iron and troilite are rare. An anomalous Fe-Mn-Mg-Ca-Cr monosulfied, of which composition lies intermediate between alabandite in EL chondrites and niningerite in EH chondrites, occurs in the interstices of the clast. The heterogeneous matrix consists of enstatite, forsterite, glass, fine-grained materials, and rare troilite. Chemical compositions of bulk meteorite, clast, and matrix obtained by the broad beam analysis of a microprobe are highly fractionated. Both the clast and matrix are especially depleted in siderophile elements, which is in accordance with apparent depletion of metallic iron over the thin section. Aluminum, Fe, Na, Si, Ca, and S are enriched in the matrix portion; on the contrary, Mg is enriched in the clast. Texture, mineral assemblage, and mineral compositions along with oxygen isotopic compositions (T. K. MAYEDA and R. N. CLAYTON; Papers presented to the 14th Symposium on Antarctic Meteorites, Tokyo, Natl Inst. Polar Res., 172,1989) suggest that Y-75261 is a breccia related to enstatite chondrites. The CaO content of enstatite, Ni, Si, and P contents of kamacite, and Ti and Cr contents of troilite indicate a closer affinity to EH chondrites than to EL\u27s in spite of the intermediate composition of the sulfide

Yamato-8002: Partial melting residue on the"unique"chondriteparent body

Yamato-8002 is classified as a "unique" meteorite having a granoblastic texture with olivine and orthopyroxene and interstitial diopside, plagioclase, spinel, kamacite schreibersite, troilite, and rare graphite. Olivine, orthopyroxene, and clinopyroxene are homogeneous with respect to Mg and Fe, but Ca in pyroxenes are zoned. Plagioclase and spinel are heterogeneous within and among grains. Mineral compositions, particularly plagioclase, spinel and trace elements in all minerals along with oxygen isotopic compositions suggest a genetic link to Y-74063,Y-75274,ALH77081,Y-791493,Acapulco, and Lodran. They were derived from a common precursor through different degrees of partial melting; Y-8002 and Y-75274 have the highest Mg/(Mg+Fe) ratios of olivine, pyroxenes, and spinel, the highest An mol% of plagioclase, and the higest Cr/(Cr+Al) ratio of spinel, indicating formation through the highest degree of partial melting. They were reduced during melting, resulting in crystallization of extremely magnesian minerals. Y-74063,ALH77081,Y-791493,Lodran, and Acapulco possess nearly primary composition of the ferromagnesian minerals excepting that some have lost and some have added partial melts. The partial melting model is supported by the REE patterns; Y-74063 and ALH77081 are flat, Y-8002 and Lodran are heavy REE enriched, and Acapulco is light REE enriched. Positive or negative Eu anomalies are general in these meteorites, suggesting addition or extraction of interstitial melt rich in plagioclase component. The precursor is chondritic with higher Mg/(Mg+Fe) ratio and higher Cr and Mn contents than ordinary chondrites, and is tentatively called a "U (nique)" chondrite. Y-74357,Y-78230,and MAC88177 are probably related to the "U" chondrite. Oxygen isotopic heterogeneity of those meteorites may be due to weathering on the Antarctic ice, and the effect of weathering was excluded by assuming that all oxygen in Fe_2O_3 was from Antarctic ice. The calculated compositions are similar to each other, suggesting their derivation from a common precursor

Vaporization experiments in the system plagioclase-hydrogen

Vaporization experiments in the system plagioclase (An_)-hydrogen were carried out at temperatures between 1200 and 1475℃ and in the pressure range from 10^ to 10^ bar. After partial vaporization, originally homogeneous plagioclase became zoned with increase of CaO and decrease of Na_2O from core to rim. The compositional change plotted on Si-Na-Ca, Al-Na-Ca, and Al-Na-Si diagrams revealed that plagioclase vaporized incongruently to form a gas with an atomic ratio close to Si : Al : Na=1 : 1 : 1 and non-stoichiometric residue over wide ranges of total pressure and oxygen fugacity. Increase of total pressure, which corresponds to increase of hydrogen pressure in the present experiments, enhanced vaporization; the Na_2O content at the surface of residue decreased and the depth of the Na_2O-depleted zone from the surface to the interior of the charges increased. Hydrogen may play the role of catalyst for the vaporization reaction. Another explanation for the role of hydrogen is that plagioclase reacts with carbon from the sample container and hydrogen to form a gas, carbon monoxide or dioxide, and methane. Non-stoichiometric composition of plagioclase in mare basalts may be due to vaporization in the high vacuum of the lunar surface

PARAMETRIC-PEARSON-BASED INDEPENDENT COMPONENT ANALYSIS FOR FREQUENCY-DOMAIN BLIND SPEECH SEPARATION

ABSTRACT Separation performance is improved in frequency

Topkapı Sarayı Müzesinde Türk saatleri

Taha Toros Arşivi, Dosya No: 114-Müzelerİstanbul Kalkınma Ajansı (TR10/14/YEN/0033) İstanbul Development Agency (TR10/14/YEN/0033

Organic chemical variation between hydrous and anhydrous Antarctic micrometeorites

第6回極域科学シンポジウム[OA] 南極隕石11月17日（火）　国立国語研究所 2階 講

Formation of an Ultracarbonaceous Antarctic Micrometeorite through Minimum Aqueous Alteration in a Small Porous Icy Body

A comprehensive study of the organic chemistry and mineralogy of an ultracarbonaceous micrometeorite (UCAMM D05IB80) collected from near the Dome Fuji Station, Antarctica, was carried out to understand the genetic relationship among organic materials, silicates, and water. The micrometeorite is composed of a dense aggregate of ∼5 µm-sized hollow ellipsoidal organic material containing submicrometer-sized phases such as glass with embedded metal and sulfides (GEMS) and mineral grains. There is a wide area of organic material (∼15 × 15 μm) in its interior. Low-Ca pyroxene is much more abundant than olivine and shows various Mg/(Mg + Fe) ratios ranging from ∼1.0 to 0.78, which is common to previous works on UCAMMs. By contrast, GEMS grains in this UCAMM have unusual chemical compositions. They are depleted in both Mg and S, which suggests that these elements were leached out from the GEMS grains during very weak aqueous alteration, without the formation of phyllosilicates. The organic materials have two textures—smooth and globular with an irregular outline—and these are composed of imine, nitrile and/or aromatic nitrogen heterocycles, and amide. The ratio of nitrogen to carbon (N/C) in the smooth region of the organics is ∼0.15, which is five times higher than that of insoluble organic macromolecules in types 1 and 2 carbonaceous chondritic meteorites. In addition, the UCAMM organic materials are soluble in epoxy and are thus hydrophilic; this polar nature indicates that they are very primitive. The surface of the material is coated with an inorganic layer, a few nanometers thick, that consists of C, O, Si, S, and Fe. Sulfur is also contained in the interior, implying the presence of organosulfur moieties. There are no isotopic anomalies of D, 13C, or 15N in the organic material. Interstellar photochemistry alone would not be sufficient to explain the N/C ratio of the UCAMM organics; therefore, we suggest that a very small amount of fluid on a comet must have been necessary for the formation of the UCAMM. The GEMS grains depleted in Mg and S in the UCAMM prove a very weak degree of aqueous alteration; weaker than that of carbonaceous chondrites. Short-duration weak alteration probably caused by planetesimal shock locally melted cometary ice grains and released water that dissolved the organics; the fluid would likely have not mobilized because of the very low thermal conductivity of the porous icy body. This event allowed the formation of the large organic puddle of the UCAMM, as well as organic matter sulfurization, formation of thin membrane-like layers of minerals, and deformation of organic nanoglobules.アクセプト後にタイトル・アブストラクト等変更あり、著者最終稿は変更前のタイトル"Formation of an Ultracarbonaceous Antarctic Micrometeorite through Minimum Aqueous Alteration in a Small Porous Icy Body"This work was supported by a Grant-in-Aid for Scientific Research from the Japanese Ministry of Education, Culture, Sports, Science and Technology (No. 22224010, PI: H. Nagahara). The STXM facility at the beamline 5.3.2.2, ALS, is supported by the Department of Energy, Basic Energy Sciences Program