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One important cause of changes in the Earth's surface environment is activity in the mantle and core of the deep Earth.Changes in the Earth's surface environment, on the other hand, profoundly influence processes in its deep interior. In the Institute for Frontier Research on Earth Evolution (IFREE), we focus on research to understand the relation and interactions between observed surface variations and the dynamics in the Earth's interior, and to explain the Earth's evolution over the past 200 million years. To reach this goal, the research program for Mantle Core Dynamics will carry out the following research projects.
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How has the Earth evolved over the past 4.6 billion years, and what is its future likely to be? The restless“subduction factory”and episodic“mantle plumes”hold the keys to much of Earth's continuing evolution.
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Cooling of the Earth is a process that has taken place continuously ever since its formation. The formation, evolution, and subduction of the lithospheric plates are the surface expression of this cooling. The motion of these plates, which can be thought of as a cooling system for "heat engine" Earth, is responsible for the occurrence of internal and surface phenomena occurring over a wide range of spatial and temporal scales, from rapid events such as earthquakes and volcanic eruptions which can have a pronounced impact on our daily lives, to the formation of mountain ranges, island arcs and marginal seas which occur over geologic time scales of millions of years.
This research program is focused especially on subduction zones, where all aspects of plate structure and deformation are represented, including rapid processes such as large-scale rupture of plate boundaries in interplate earthquakes. Research into lithospheric structure, numerical modeling and material sciences will be integrated into a comprehensive understanding of plate behavior.
The research in this program will be conducted in close cooperation with other research programs involved in related fields, such as the other programs of IFREE. Also, it will play an important role in promoting the scientific objectives of the program for deep drilling of the interplate seismogenic zone.
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Based on the records from marine sediment cores, climatic changes over the last 200 million years is a convolution of many climatic variables caused by various mechanisms and periodicity. They include those that originated from geological events like a bolide impact and monsoon establishment, and periodic glacial-interglacial cycles, and quasi-periodic Dansgaard/Oeschgar Events and Heinrich Events. They can be grouped into either internal or external causes; the former includes distribution and rate constants of elemental cycles in the crust and mantle, whereas the latter includes bolide impact and Earth's orbital forcing. The ultimate goal of our group's research is to understand the mechanisms driving these changes.
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The Center for D/S Analyses contributes to the four Programs of IFREE by putting large facilities, such as the Global observation networks, ultra-fast supercomputer and ocean-drilling vessel, to practical use. Since the Center is essential to research on each Program, it is necessary to set up the Center together with the four Programs. The Center is basically consists of three divisions that are called the Sample Analysis Division, the Pacific Data Network Division and the Seismic Data Processing Division. The main tasks of the latter two divisions are to maintain, archive and analyse data from geophysical networks and also to analyse seismic and geophysical data. That of the first division is to analyse core samples obtained from IFREE and OD21. The Center for Data and Sample Analyses provides basic research support for IFREE.
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