Abstract Most existing solids are categorised as diamagnetic or weak paramagnetic materials. The possibility of magnetic motion has not been intensively considered for these materials. Here, we demonstrate for the first time that ensembles of heterogeneous particles (diamagnetic bismuth, diamond and graphite particles, as well as two paramagnetic olivines) can be dynamically separated into five fractions by the low field produced by neodymium (NdFeB) magnets during short-duration microgravity ( μg ). This result is in contrast to the generally accepted notion that ordinary solid materials are magnetically inert. The materials of the separated particles are identified by their magnetic susceptibility (χ), which is determined from the translating velocity. The potential of this approach as an analytical technique is comparable to that of chromatography separation because the extraction of new solid phases from a heterogeneous grain ensemble will lead to important discoveries about inorganic materials. The method is applicable for the separation of the precious samples such as lunar soils and/or the Hayabusa particles recovered from the asteroids, because even micron-order grains can be thoroughly separated without sample-loss.
We obtained the radiometric ages of detrital zircons from two samples of paragneiss from Oki-Dogo Island, Japan, from the 238U/206Pb ratio and isotopic composition of Pb determined using a Sensitive High-Resolution Ion MicroProbe (SHRIMP II). The zircons show two main age clusters around 2200 Ma and 1800 Ma, with some discordant ages. One zircon grain has a rim with a concordant age of 236 ± 3 Ma, which is consistent with the age of peak metamorphism in the Hida Metamorphic Belt. The modal proportions of zircon ages from Oki-Dogo Island are clearly different from those for paragneiss of the Hida Terrane. This indicates that the Oki Gneiss is derived from an Early Proterozoic rock and is different from the Hida Gneiss in terms of provenance and/or the depositional age of the parent sediment.
Most solid particles, composed of diamagnetic or weak paramagnetic materials, cannot be extracted by a conventional magnetic separator. Here we report that an ensemble of heterogeneous particles, composed of bismuth, gold, graphite and rock forming minerals are separated into fractions of different materials by small NdFeB magnetic plates. It is based on a recent finding that acceleration of a translating particle, induced by magnetic volume force in an area of field gradient, is uniquely determined by intrinsic susceptibility of material; the acceleration is independent to particle mass. The setup will serve as an effective technique of pre-treatment in analysing mixture of heterogeneous particles; such a technique is desired in various research fields of science, and the magnetic separation may play a role of a "chromatography technique" conventionally used in the analysis of organic molecules. The portable and low-cost system could provide a breakthrough for on-site research in industrial and medical fields as well as in resource explorations in nature. Extraction of rare materials such as gold or platinum becomes possible in a hazardless manner.
Abstract The Maizuru terrane, distributed in the Inner Zone of southwest Japan, is divided into three subzones (Northern, Central and Southern), each with distinct lithological associations. In clear contrast with the Southern zone consisting of the Yakuno ophiolite, the Northern zone is subdivided into the western and eastern bodies by a high‐angle fault, recognized mainly by the presence of deformed granitic rocks and pelitic gneiss. This association suggests an affinity with a mature continental block; this is supported by the mode of occurrence, and petrological and isotopic data. Newly obtained sensitive high mass‐resolution ion microprobe (SHRIMP) zircon U–Pb ages reveal the intrusion ages of 424 ± 16 and 405 ± 18 Ma (Siluro–Devonian) for the granites from the western body, and 249 ± 10 and 243 ± 19 Ma (Permo–Triassic) for the granodiorites from the eastern body. The granites in the western body also show inherited zircon ages of around 580 and 765 Ma. In addition, electron probe microanalysis (EPMA) monazite U–Th–total Pb dating gives around 475–460 Ma. The age of intrusion, inherited ages, mode of occurrence, and geological setting of the Siluro–Devonian granites of the Northern zone all show similarities with those of the Khanka Massif, southern Primoye, Russia, and the Hikami granitic rocks of the South Kitakami terrane, Northeast Japan. We propose that both the Siluro–Devonian and Permo–Triassic granitic rocks of the Northern zone are likely to have been juxtaposed through the Triassic–Late Jurassic dextral strike‐slip movement, and to have originated from the Khanka Massif and the Hida terrane, respectively. This study strongly supports the importance of the strike‐slip movement as a mechanism causing the structural rearrangement of the Paleozoic–Mesozoic terranes in the Japanese Islands, as well as in East Asia.
Understanding the origin and evolution of near-Earth asteroids (NEAs) is an issue of scientific interest and practical importance because NEAs are potentially hazardous to the Earth. However, when and how NEAs formed and their evolutionary history remain enigmas. Here, we report the U-Pb systematics of Itokawa particles for the first time. Ion microprobe analyses of seven phosphate grains from a single particle provide an isochron age of 4.64 ± 0.18 billion years (1σ). This ancient phosphate age is thought to represent the thermal metamorphism of Itokawa's parent body, which is identical to that of typical LL chondrites. In addition, the incorporation of other particles suggests that a significant shock event might have occurred 1.51 ± 0.85 billion years ago (1σ), which is significantly different from the shock ages of 4.2 billion years of the majority of shocked LL chondrites and similar to that of the Chelyabinsk meteorite. Combining these data with recent Ar-Ar studies on particles from a different landing site, we conclude that a globally intense impact, possibly a catastrophic event, occurred ca. 1.4 Ga ago. This conclusion enables us to establish constraints on the timescale of asteroid disruption frequency, the validity of the crater chronology and the mean lifetime of small NEAs.
Research Article| November 01, 2005 North-south extension in the Tibetan crust triggered by granite emplacement Mutsuki Aoya; Mutsuki Aoya 1Institute of Geology and Geoinformation, National Institute of Advanced Industrial Science and Technology, Central 7, Tsukuba 305-8567, Japan Search for other works by this author on: GSW Google Scholar Simon R. Wallis; Simon R. Wallis 2Department of Earth and Planetary Sciences, Graduate School of Environmental Studies, Nagoya University, Nagoya 464-8602, Japan Search for other works by this author on: GSW Google Scholar Kentaro Terada; Kentaro Terada 3Department of Earth and Planetary Systems Science, Graduate School of Science, Hiroshima University, Hiroshima 739-8526, Japan Search for other works by this author on: GSW Google Scholar Jeffrey Lee; Jeffrey Lee 4Department of Geological Sciences, Central Washington University, Ellensburg, Washington 98926, USA Search for other works by this author on: GSW Google Scholar Tetsuo Kawakami; Tetsuo Kawakami 5Department of Earth Sciences, Faculty of Education, Okayama University, Okayama 700-8530, Japan Search for other works by this author on: GSW Google Scholar Yu Wang; Yu Wang 6Department of Geology, China University of Geosciences, Beijing 100083, China Search for other works by this author on: GSW Google Scholar Matt Heizler Matt Heizler 7New Mexico Bureau of Mines and Mineral Resources, New Mexico Tech, 801 Leroy Place, Socorro, New Mexico 87801-4796, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Mutsuki Aoya 1Institute of Geology and Geoinformation, National Institute of Advanced Industrial Science and Technology, Central 7, Tsukuba 305-8567, Japan Simon R. Wallis 2Department of Earth and Planetary Sciences, Graduate School of Environmental Studies, Nagoya University, Nagoya 464-8602, Japan Kentaro Terada 3Department of Earth and Planetary Systems Science, Graduate School of Science, Hiroshima University, Hiroshima 739-8526, Japan Jeffrey Lee 4Department of Geological Sciences, Central Washington University, Ellensburg, Washington 98926, USA Tetsuo Kawakami 5Department of Earth Sciences, Faculty of Education, Okayama University, Okayama 700-8530, Japan Yu Wang 6Department of Geology, China University of Geosciences, Beijing 100083, China Matt Heizler 7New Mexico Bureau of Mines and Mineral Resources, New Mexico Tech, 801 Leroy Place, Socorro, New Mexico 87801-4796, USA Publisher: Geological Society of America Received: 20 Apr 2005 Revision Received: 04 Jul 2005 Accepted: 06 Jul 2005 First Online: 02 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (2005) 33 (11): 853–856. https://doi.org/10.1130/G21806.1 Article history Received: 20 Apr 2005 Revision Received: 04 Jul 2005 Accepted: 06 Jul 2005 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Mutsuki Aoya, Simon R. Wallis, Kentaro Terada, Jeffrey Lee, Tetsuo Kawakami, Yu Wang, Matt Heizler; North-south extension in the Tibetan crust triggered by granite emplacement. Geology 2005;; 33 (11): 853–856. doi: https://doi.org/10.1130/G21806.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract We combine zircon sensitive high-resolution ion microprobe U-Pb spot dating and mica 40Ar-39Ar plateau ages with field-geological and geochemical constraints from the Mala shan area of Southern Tibet to show that the deformed granite core of the North Himalayan metamorphic domes in this area is not Indian basement, but was intruded and deformed during the Himalayan orogeny. Microstructural observations reveal that a transition from top-to-the-south thrust-related to top-to-the-north extension-related deformation occurred during granite intrusion and related metamorphism. This suggests that intrusion triggered the onset of extensional tectonics in the Tibetan middle to upper crust. Expected positive feedback mechanisms between decompression melting leading to more intrusion and more extensional deformation suggest that this mechanism may have been important on a regional scale. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.
We report ion microprobe U‐Pb dating of phosphates in lunar meteorite “Elephant Moraine 87521 (EET87521),” which is a fragmental breccia consisting of Very‐Low Ti (VLT) basaltic clasts and a small component of highland‐derived materials. The observed Pb‐Pb age of phosphates in EET87521 is 3503 ± 140 Ma, which is distinct from the results from previous chronological studies on VLT mare basalt of 3.2–3.3 Ga for LUNA‐24. This suggests that the VLT basalt volcanism appears to have been prolonged on the Moon. Moreover, the age is apparently different from those of other VLT meteorites (3.8 Ga for QUE94281 and 4.0 & 4.4 Ga for Yamato793274), which are proposed to have been launched by a single impact event based on the similarity of launching ages, mineralogical and geochemical signatures. This evidence questions the validities of bulk age analyses for the Yamato & QUE meteorites in the literature and/or the hypothesis of a single‐crater origin.
