High-reliability zircon separation for hunting the oldest material on Earth: An automatic zircon separator with image-processing/microtweezers-manipulating system and double-step dating
Despite the recent development in radiometric dating of numerous zircons by LA-ICPMS, mineral separation still remains a major obstacle, particularly in the search for the oldest material on Earth. To improve the efficiency in zircon separation by an order of magnitude, we have designed/developed a...
| Main Authors: | , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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Elsevier
2018-07-01
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| Series: | Geoscience Frontiers |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S1674987117300956 |
| _version_ | 1797713536045023232 |
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| author | Yukio Isozaki Shinji Yamamoto Shuhei Sakata Hideyuki Obayashi Takafumi Hirata Ken-ichi Obori Toshinori Maebayashi Satoshi Takeshima Toshikazu Ebisuzaki Shigenori Maruyama |
| author_facet | Yukio Isozaki Shinji Yamamoto Shuhei Sakata Hideyuki Obayashi Takafumi Hirata Ken-ichi Obori Toshinori Maebayashi Satoshi Takeshima Toshikazu Ebisuzaki Shigenori Maruyama |
| author_sort | Yukio Isozaki |
| collection | DOAJ |
| description | Despite the recent development in radiometric dating of numerous zircons by LA-ICPMS, mineral separation still remains a major obstacle, particularly in the search for the oldest material on Earth. To improve the efficiency in zircon separation by an order of magnitude, we have designed/developed a new machine – an automatic zircon separator (AZS). This is designed particularly for automatic pick-up of 100 μm-sized zircon grains out of a heavy mineral fraction after conventional separation procedures. The AZS operates in three modes: (1) image processing to choose targeted individual zircon grains out of all heavy minerals spread on a tray, (2) automatic capturing of the individual zircon grains with micro-tweezers, and (3) placing them one-by-one in a coordinated alignment on a receiving tray. The automatic capturing was designed/created for continuous mineral selecting without human presence for many hours. This software also enables the registration of each separated zircon grain for dating, by recording digital photo-image, optical (color) indices, and coordinates on a receiving tray. We developed two new approaches for the dating; i.e. (1) direct dating of zircons selected by LA-ICPMS without conventional resin-mounting/polishing, (2) high speed U-Pb dating, combined with conventional sample preparation procedures using the new equipment with multiple-ion counting detectors (LA-MIC-ICPMS). With the first approach, Pb-Pb ages obtained from the surface of a mineral were crosschecked with the interior of the same grain after resin-mounting/polishing. With the second approach, the amount of time required for dating one zircon grain is ca. 20 s, and a sample throughput of >150 grains per hour can be achieved with sufficient precision (ca. 0.5%).We tested the practical efficiency of the AZS, by analyzing an Archean Jack Hills conglomerate in Western Australia with the known oldest (>4.3 Ga) zircon on Earth. Preliminary results are positive; we were able to obtain more than 194 zircons that are over 4.0 Ga out of ca. 3800 checked grains, and 9 grains were over 4300 Ma with the oldest at 4371 ± 7 Ma. This separation system by AZS, combined with the new approaches, guarantees much higher yield in the hunt for old zircons. Keywords: Hadean, Zircon, U-Pb dating, LA-ICPMS, Automatic mineral separator, Primordial crust |
| first_indexed | 2024-03-12T07:38:03Z |
| format | Article |
| id | doaj.art-24ef833ac5eb48e8aa6496f644b67b0f |
| institution | Directory Open Access Journal |
| issn | 1674-9871 |
| language | English |
| last_indexed | 2024-03-12T07:38:03Z |
| publishDate | 2018-07-01 |
| publisher | Elsevier |
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| series | Geoscience Frontiers |
| spelling | doaj.art-24ef833ac5eb48e8aa6496f644b67b0f2023-09-02T21:25:35ZengElsevierGeoscience Frontiers1674-98712018-07-019410731083High-reliability zircon separation for hunting the oldest material on Earth: An automatic zircon separator with image-processing/microtweezers-manipulating system and double-step datingYukio Isozaki0Shinji Yamamoto1Shuhei Sakata2Hideyuki Obayashi3Takafumi Hirata4Ken-ichi Obori5Toshinori Maebayashi6Satoshi Takeshima7Toshikazu Ebisuzaki8Shigenori Maruyama9Department of Earth Science and Astronomy, The University of Tokyo, Komaba, Meguro, Tokyo 153-8902, Japan; Corresponding author.Department of Earth Science and Astronomy, The University of Tokyo, Komaba, Meguro, Tokyo 153-8902, Japan; Department of Human Environmental Studies, Yokohama National University, Hodogaya, Yokohama 240-8501, JapanDepartment of Earth Science and Astronomy, The University of Tokyo, Komaba, Meguro, Tokyo 153-8902, Japan; Department of Chemistry, Gakushuin University, Mejiro, Toshima, Tokyo 171-8588, JapanDepartment of Geology and Mineralogy, Kyoto University, Kitashirakawa Oiwakecho, Sakyo-ku, Kyoto 606-8502, JapanDepartment of Geology and Mineralogy, Kyoto University, Kitashirakawa Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan; Geochemical Research Center, The University of Tokyo, Hongo 7-3-1, Bunkyo, Tokyo 113-0033, JapanHoriba Ltd., Kanda, Chiyoda, Tokyo 101-0063, JapanMicroSupport Co. Ltd., Hiratsuka, Kanagawa 254-0035, JapanMitani Corporation, Takada, Toshima, Tokyo 171-0033, JapanRiken, Wako, Saitama 351-0198, JapanELSI, Tokyo Institute of Technology, Meguro, Tokyo 152-8551, JapanDespite the recent development in radiometric dating of numerous zircons by LA-ICPMS, mineral separation still remains a major obstacle, particularly in the search for the oldest material on Earth. To improve the efficiency in zircon separation by an order of magnitude, we have designed/developed a new machine – an automatic zircon separator (AZS). This is designed particularly for automatic pick-up of 100 μm-sized zircon grains out of a heavy mineral fraction after conventional separation procedures. The AZS operates in three modes: (1) image processing to choose targeted individual zircon grains out of all heavy minerals spread on a tray, (2) automatic capturing of the individual zircon grains with micro-tweezers, and (3) placing them one-by-one in a coordinated alignment on a receiving tray. The automatic capturing was designed/created for continuous mineral selecting without human presence for many hours. This software also enables the registration of each separated zircon grain for dating, by recording digital photo-image, optical (color) indices, and coordinates on a receiving tray. We developed two new approaches for the dating; i.e. (1) direct dating of zircons selected by LA-ICPMS without conventional resin-mounting/polishing, (2) high speed U-Pb dating, combined with conventional sample preparation procedures using the new equipment with multiple-ion counting detectors (LA-MIC-ICPMS). With the first approach, Pb-Pb ages obtained from the surface of a mineral were crosschecked with the interior of the same grain after resin-mounting/polishing. With the second approach, the amount of time required for dating one zircon grain is ca. 20 s, and a sample throughput of >150 grains per hour can be achieved with sufficient precision (ca. 0.5%).We tested the practical efficiency of the AZS, by analyzing an Archean Jack Hills conglomerate in Western Australia with the known oldest (>4.3 Ga) zircon on Earth. Preliminary results are positive; we were able to obtain more than 194 zircons that are over 4.0 Ga out of ca. 3800 checked grains, and 9 grains were over 4300 Ma with the oldest at 4371 ± 7 Ma. This separation system by AZS, combined with the new approaches, guarantees much higher yield in the hunt for old zircons. Keywords: Hadean, Zircon, U-Pb dating, LA-ICPMS, Automatic mineral separator, Primordial crusthttp://www.sciencedirect.com/science/article/pii/S1674987117300956 |
| spellingShingle | Yukio Isozaki Shinji Yamamoto Shuhei Sakata Hideyuki Obayashi Takafumi Hirata Ken-ichi Obori Toshinori Maebayashi Satoshi Takeshima Toshikazu Ebisuzaki Shigenori Maruyama High-reliability zircon separation for hunting the oldest material on Earth: An automatic zircon separator with image-processing/microtweezers-manipulating system and double-step dating Geoscience Frontiers |
| title | High-reliability zircon separation for hunting the oldest material on Earth: An automatic zircon separator with image-processing/microtweezers-manipulating system and double-step dating |
| title_full | High-reliability zircon separation for hunting the oldest material on Earth: An automatic zircon separator with image-processing/microtweezers-manipulating system and double-step dating |
| title_fullStr | High-reliability zircon separation for hunting the oldest material on Earth: An automatic zircon separator with image-processing/microtweezers-manipulating system and double-step dating |
| title_full_unstemmed | High-reliability zircon separation for hunting the oldest material on Earth: An automatic zircon separator with image-processing/microtweezers-manipulating system and double-step dating |
| title_short | High-reliability zircon separation for hunting the oldest material on Earth: An automatic zircon separator with image-processing/microtweezers-manipulating system and double-step dating |
| title_sort | high reliability zircon separation for hunting the oldest material on earth an automatic zircon separator with image processing microtweezers manipulating system and double step dating |
| url | http://www.sciencedirect.com/science/article/pii/S1674987117300956 |
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