- 著者
- Kenta YOSHIDA Tatsu KUWATANI Atsushi YASUMOTO Satoru HARAGUCHI Kenta UEKI Hikaru IWAMORI
- 出版者
- Japan Association of Mineralogical Sciences
- 雑誌
- Journal of Mineralogical and Petrological Sciences (ISSN:13456296)
- 巻号頁・発行日
- pp.171127, (Released:2018-06-07)
- 被引用文献数
- 3
Conventional clustering algorithms such as k–means and fuzzy c–means (FCM) cluster analysis do not fully utilize the spatial distribution information of geologic samples. In this paper, we propose GEOFCM, a new clustering method for geochemical datasets with location coordinates. A spatial FCM algorithm originally constructed for image segmentation was modified for application to a sparse and unequally–spaced dataset. The proposed algorithm evaluates the membership function of each sample using neighboring samples as a weighting function. To test the proposed algorithm, a synthetic dataset was analyzed by several hyper–parameter settings. Applying this algorithm to a geochemical dataset of granitoids in the Ina–Mikawa district of the Ryoke belt shows that samples collected from the same geological unit are likely to be classified as the same cluster. Moreover, overlapping geochemical trends are classified consistently with spatial distribution, and the result is more robust against noise addition than standard FCM analysis. The proposed method is a powerful tool to use with geological datasets with location coordinates, which are becoming increasingly available, and can help find overviews of complicated multidimensional data structure.
- 著者
- HIKARU IWAMORI HITOMI NAKAMURA
- 出版者
- GEOCHEMICAL SOCIETY OF JAPAN
- 雑誌
- GEOCHEMICAL JOURNAL (ISSN:00167002)
- 巻号頁・発行日
- vol.46, no.4, pp.e39-e46, 2012-08-20 (Released:2013-11-08)
- 参考文献数
- 37
- 被引用文献数
- 6 22
In order to decipher the mantle geochemical heterogeneity that reflects material differentiation and circulation within the Earth, we examined mid-ocean ridge basalts (MORB), ocean island basalts (OIB) and arc basalts (AB), in terms of the radiogenic isotopic variability and its geographical distribution. It has been found that the Sr, Nd and Pb isotopic ratios of MORB, OIB and AB exhibit a two-dimensional structure, and are mostly distributed on the same compositional plane that is spanned by two independent components (IC1 and IC2). One of the two components (IC2) divides geochemically the mantle broadly into the Eastern and Western Hemispheres. Inspection of the geochemical nature of IC2 suggests that it may represent a fluid mobile component recycled through subduction zones. The mantle geochemical domain beneath the Eastern Hemisphere is enriched in the fluid mobile component, possibly by focused subduction towards the supercontinent Pangea which was surrounded by subduction zones. Although the present-day continents have been dispersed since then, the geochemical domain has seemingly been anchored to the asthenosphere without moving with the continents.
- 著者
- Satoru Haraguchi Kenta Ueki Kenta Yoshida Tatsu Kuwatani Mika Mohamed Shunsuke Horiuchi Hikaru Iwamori
- 出版者
- The Geological Society of Japan
- 雑誌
- 地質学雑誌 (ISSN:00167630)
- 巻号頁・発行日
- vol.124, no.12, pp.1049-1054, 2018-12-15 (Released:2019-03-15)
- 参考文献数
- 11
- 被引用文献数
- 5
A geochemical database for the basement rocks of the Japanese islands has been constructed. These data were previously published in Japanese domestic journals and bulletins not readily accessible to the international community. The database includes 5818 samples from 224 articles, and provides major and trace element concentrations, isotopic ratios, geographical coordinates (latitude, longitude, and altitude) of sampling points, and geological and lithological information. These data are provided in a unified and consistent format as an Excel spreadsheet, which can be efficiently utilized for statistical analyses and data-driven approaches in geochemistry, geology, and petrology.