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Carbon Dioxide Induces Partial Melting in the Asthenosphere- A big step to settle arguments on plate tectonics - | |
admin | |
2017-02-02 | |
发布年 | 2017 |
语种 | 英语 |
国家 | 日本 |
领域 | 资源环境 |
正文(英文) |
Overview Dr. Shiki Machida at Research and Development Center for Submarine Resources, the Japan Agency for Marine-Earth Science and Technology (JAMSTEC: Asahiko Taira, President) carried out high-pressure melting experiments to define magma genesis of petit-spot*1 in the flexed region of the northwestern Pacific plate. The results revealed that the petit-spot magmas are originated in the asthenosphere*2 in the upper mantle. The work was carried out in collaboration with Dr. Tetsu Kogiso, Professor at Graduate School of Human and Environmental Studies, Kyoto University (Juichi Yamagiwa, President) and Dr. Naoto Hirano, Associate Professor at Tohoku University (Susumu Satomi, President). It has already been known that the primary petit-spot magma includes approximately 10% carbon dioxide (CO2), which is much higher amount of that in magmas for the other type of volcanism. In this study, scientists demonstrated that 1) CO2 induces partial melting in the asthenosphere; and 2) plate flexure allows these magmas to intrude into the lower part of plate, which are then in equilibrium with surrounding mantle peridotites before eruption to form petit spot volcanoes. Here, petit-spot is a definitive evidence for partial melting in the asthenosphere caused by CO2. According to the plate tectonic theory, plates move on top of the weak asthenosphere. Subduction of these plates causes earthquakes, volcanic activities and orogeny. Thus, the asthenosphere plays a critical role on the movement of plates across the Earth's surface, and is an important layer to characterize the Earth having active surface and continent, which is a unique planet in the solar system. Since the establishment of the plate tectonic theory, there have been arguments whether the weak asthenosphere is caused by partial melting of mantle rocks or not. These results strongly support the partial melting hypothesis, providing a big clue to further elucidate the mechanism of plate movements and mantle convection. This work was supported by JSPS KAKENHI Grant Number JP20740293, JSPS23740379, JP24654180 and a Toray Science and Technology grant No. 11-5208. The above results were published in the Nature Communications on February 2, 2017 (JST).
Title: Petit-spot as definitive evidence for partial melting in the asthenosphere caused by CO2 *1 Petit-spots
*2 Asthenosphere and plates (lithosphere) ![]() Figure 1. Bathymetric maps for the northwestern Pacific showing the position of the petit-spot volcanoes investigated in this study. The open red star corresponds to the region shown in b). ![]() Figure 2. (a) One of sample basalts used for high-pressure melting experiments. Its chemical composition is likely to be very similar to those of primary magmas. (b) Sampling carried out by Shinkai 6500 Dive 879 during YK05-06 cruise. ![]() Figure 3. Mixture of pre-dried reagents of oxides, hydroxides, phosphate and carbonates, which represents the major elements, CO2 and H2O composition of the primary magma for petit-spot volcano. This mixture is used as starting material of the melting experiments. ![]() Figure 4. Boyd–England-type 1/2-in-diameter piston–cylinder apparatus used for the melting experiments at Kyoto University. ![]() Figure 5. Model for petit-spot volcanism in the northwest Pacific (modified Fig. 3C in Hirano et al. (2006) based on results of this study). Contacts:
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来源平台 | Japan Agency for Marine-Earth Science and Technology |
文献类型 | 新闻 |
条目标识符 | http://119.78.100.173/C666/handle/2XK7JSWQ/104365 |
专题 | 资源环境科学 |
推荐引用方式 GB/T 7714 | admin. Carbon Dioxide Induces Partial Melting in the Asthenosphere- A big step to settle arguments on plate tectonics -. 2017. |
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