Browsing ELibrary by Author "Nakamura T."

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BULK MINERALOGY OF INDIVIDUAL MICROMETEORITES DETERMINED BY X-RAY DIFFRACTION ANALYSIS AND TRANSMISSION ELECTRON MICROSCOPY

Nakamura T.; Noguchi T.; Yada T.; Nakamuta Y.; Takaoka N. (2001)

Bulk mineralogy of individual fine-grained micrometeorites from 50 to 200 μm in diameter was determined on the basis of the powder X-ray diffraction patterns and the observation of internal textures by a transmission ...
EVALUATING THE THERMAL METAMORPHISM OF CM CHONDRITES BY USING THE PYROLYTIC BEHAVIOR OF CARBONACEOUS MACROMOLECULAR MATTER

Kitajima F.; Nakamura T.; Takaoka N.; Murae T. (2002)

The degrees of thermal metamorphism of 10 CM chondrites and of the Allende CV3 chondrite were evaluated from the viewpoint of ''graphitization'' of the carbonaceous macromolecular matter by means of flash pyrolysis-gas ...
FORMATION HISTORY OF CI-LIKE PHYLLOSILICATE-RICH CLASTS IN THE TSUKUBA METEORITE INFERRED FROM MINERALOGY AND NOBLE GAS SIGNATURES

Nakashima D.; Nakamura T.; Noguchi T. (2003)

Fine-grained, angular black clasts with longest dimensions up to 800 μm were found, dispersed in a brecciated region in the Tsukuba meteorite. The clasts, much darker than the dark portions of the light-dark structure in ...
FORMATION PROCESSES OF COMPOUND CHONDRULES IN CV3 CARBONACEOUS CHONDRITES: CONSTRAINTS FROM OXYGEN ISOTOPE RATIOS AND MAJOR ELEMENT CONCENTRATIONS

Akaki T.; Nakamura T. (2005)

We found thirty compound chondrules in two CV3 carbonaceous chondrites. The abundance in each meteorite relative to single chondrules is 29/1846 (1.6%) in Allende and 1/230 (0.4%) in Axtell. We examined petrologic features, ...
HETEROGENEOUS DISTRIBUTION OF SOLAR AND COSMOGENIC NOBLE GASES IN CM CHONDRITES AND IMPLICATIONS FOR THE FORMATION OF CM PARENT BODIES

Nakamura T.; Nagao K.; Metzler K.; Takaoka N. (1999)

Distribution of solar, cosmogenic, and primordial noble gases in thin slices of Murchison, Murray, and Nogoya CM carbonaceous chondrites was determined by the laser microprobe analysis so as to put some constraints on the ...
HOLOCENE PEAT BOGS IN PREBAIKALIA AS AN OBJECT OF PALEOCLIMATIC RECONSTRUCTIONS

Bezrukova E.V.; Mats V.D.; Letunova P.P.; Nakamura T.; Fuji S. (1996)

On the basis of new factual material, the history of the formation of the Prebaikalia vegetation cover is considered. For this purpose data of palynological analysis for nine sections of lacustrine-palustrine deposits were ...
IS AMINO ACID CHRONOLOGY APPLICABLE TO THE ESTIMATION OF THE GEOLOGICAL AGE OF SILICEOUS SEDIMENTS?

Harada N.; Kondo T.; Fukuma K.; Uchida M.; Nakamura T.; Iwai M.; Murayama M.; Sugawara T.; Kusakabe M. (2002)

There are few conventional dating methods that can be used to estimate the geological age of siliceous sediments on the order of 104-105 yr. In contrast, methods such as δ18O are available for dating carbonate-containing ...
MICRODISTRIBUTION OF PRIMORDIAL NOBLE GASES IN CM CHONDRITES DETERMINED BY IN SITU LASER MICROPROBE ANALYSIS: DECIPHERMENT OF NEBULAR PROCESSES - NOBLE GASES, CARBON AND AN ESCA STUDY

Nakamura T.; Nagao K.; Takaoka N. (1999)

In situ noble gas analyses using a laser microprobe with a beam diameter of 50-100 μm were performed on thin slices of Murchison and Yamato (Y-) 791198 CM carbonaceous chondrites in order to see microdistribution of ...
MINERALOGY AND NOBLE-GAS SIGNATURES OF THE CARBONATE-RICH LITHOLOGY OF THE TAGISH LAKE CARBONACEOUS CHONDRITE: EVIDENCE FOR AN ACCRETIONARY BRECCIA

Nakamura T.; Noguchi T.; Zolensky M.E.; Tanaka M. (2003)

The carbonate-rich lithology of the Tagish Lake carbonaceous chondrite was characterized by noble-gas mass spectrometry, synchrotron X-ray diffraction analysis, and transmission and scanning electron microscopy. Noble-gas ...
MINERALOGY OF PHYLLOSILICATE-RICH MICROMETEORITES AND COMPARISON WITH TAGISH LAKE AND SAYAMA METEORITES

Noguchi T.; Nakamura T.; Nozaki W. (2002)

Four phyllosilicate-rich micrometeorites (MMs) were investigated by a synchrotron radiation X-ray diffraction technique and transmission electron microscopy. Three are saponite-rich MMs and one is a serpentine-rich one. ...
NOBLE GASES IN UREILITES RELEASED BY CRUSHING

Okazaki R.; Nakamura T.; Takaoka N.; Nagao K. (2003)

Noble gases in two ureilites, Kenna and Allan Hills (ALH) 78019, were measured with two extraction methods: mechanical crushing in a vacuum and heating. Large amounts of noble gases were released by crushing, up to 26.5% ...
YAMATO 86029: AQUEOUSLY ALTERED AND THERMALLY METAMORPHOSED CI-LIKE CHONDRITE WITH UNUSUAL TEXTURES

Tonui E.R.; Zolensky M.E.; Lipschutz M.E.; Wang M.-S.; Nakamura T. (2003)

We describe the petrologic and trace element characteristics of the Yamato 86029 (Y-86029) meteorite. Y-86029 is a breccia consisting of a variety of clasts, and abundant secondary minerals including coarse- and fine-grained ...

Browsing ELibrary by Author "Nakamura T."

Browsing ELibrary by Author "Nakamura T."

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