Educational and Research Fields


[ Geology ]

1. What do you learn?
You will learn how a stratum is formed in the sea floor, and what type of record about Earth’s past and crustal deformation can be obtained from it. Subjects offered are associated with the history and development of strata (Stratigraphy, Marine Geology, and Tectonics), and also the change in Earth’s environment that can be interpreted from natural radiation or fossils found in a stratum (Radiation Environmental Geology, Marine Micropaleontology, and Historical Geology). There are also plenty of fieldwork and lab experiments to learn hands-on about strata and fossils.


Photo: Historical Geology fieldwork (geological excursion). Studying the limestone from the Quaternary period at Kume Island to see how coral reefs were formed.

You will also learn about minerals and their aggregated form, rocks, primarily from the perspectives of chemistry. Through fieldwork and experiments you will learn how to identify minerals and rocks, and perform chemical analysis. You will also learn the components of various rocks that compose a crust. You will deepen your understanding of the generation mechanism of magma at different locations, plate tectonics, crustal movements, their processes at a deep or shallow level, and how these are reflected in the make-up of volcanic rocks.


Exhibit: primary locations of magma generation

2. Main Subjects
Marine Geology and Marine Geology Experiment (Professor Masahide Furukawa) 　
Students will learn about the geological distribution and the history of formation of the Ryukyu Archipelago (nansei islands) and the seafloors in the area. In addition to lectures, students will deepen their knowledge of marine geology through the analysis of sonic profiling data of the seafloor, as well as the field observation of strata.


Photo: Inclined strata on the coast of the northern region of mainland Okinawa

Polarizing Microscope Lab and Petro/Mineral Genesis (Professor Ryuichi Shinjo)
Students will learn skills to identify and evaluate rocks and minerals using a polarizing microscope. They will also study the elemental portioning between magma and minerals, different chemical compositions of magma in various locations on Earth and the cause, and the magma process inside the crust, among others.


Fieldwork at Aguni Island. The white cliff, made up of pyroclastic flow deposits at the bottom and volcanic ash layer at the top, is simply overwhelming.

3. What type of research is being conducted?
We primarily conduct research on the development process of strata, natural radiation and radioactivity, and also microfossils. We are interested in how the seafloors around Okinawa were formed, natural radiation volume from the surface, geology of the Ryukyu Archipelago, and its causal association with yellow dust. In research projects involving microfossils, we study the change in marine environment (sea level and temperature) over time and the development history of coral reefs, by observing and analyzing extremely small fossils (microfossils) with a microscope. In order to solve the paleoecological mysteries of these microfossils, we also study the biology and ecology of living microorganisms (foraminifera: a family of star sand), and its relationship with the marine environment.


写真：星砂の電子顕微鏡写真

We are collecting rock samples in a broad area from Southern Kyushu to the Ryukyu Arc, and studying the chemical features of mantle substances associated with magma generation, and the characteristics of components supplied by subducting plates, based on the chemical composition of volcanic rocks (microelement concentration as well as Sr-Nd-Pb isotopic compositions).
We are also investigating how the mantle altered along with the formation of troughs by comparing the chemical compositions of the volcanic rocks of the Okinawa trough, which has been in existence from the early days of the formation of the back-arc basin, and the volcanic rocks of the Ryukyu Arc.

Investigating the Okinawa trough with an unmanned submarine research vessel.

4. Recent Research Projects
Islands in the South Pacific that are in danger of submergence due to a sea-level rise are composed of foraminiferal shells like star sand. Where do these foraminifera inhabit? What type of environment do they prefer? These are the questions we attempt to answer through fieldwork and culture experiments, as we consider viable ways to maintain and regenerate a beautiful island environment. (Assistant Professor Kazuhiko Fujita)


Photo: Small island made of star sand on a coral reef (Funafui Atoll, Tuvalu)

Examples of Graduation Thesis Topics
・Optimization of the concentration measurement of radon and thoron using a solid-state track detector
・Distribution of gamma radiation dose rate and its geological background in the central region of mainland Okinawa
・Research about surface radon exhalation in mainland Okinawa
・The relationship between large foraminifera assemblages and environmental factors on the insular shelf around mainland Okinawa: proposal of indicators for sedimentary environments
・Distribution of large foraminifera and its limiting factors on coral reefs of Fongafale Island, Funafuti Atoll
・Impacts of ocean acidification on the calcification of reef-dwelling foraminifera: verification by culture experiments
・Experiment attempting to efficiently remove Boron (B) from volcanic rocks
・Analysis of isotopic ratios of Boron using N-TIMS method
・Quantitative ICP-MS analysis of Boron and HFS elements (Nb, Ta, Zr, Hf) in volcanic rocks
・Sr-Nd-Pb isotopic ratio of basalt from the spreading axis of the Gulf of Eden, Northeast Africa

Instructors

Professor Masahide Furukawa　Marine Geology and Radiation Environmental Geology
Studies the islands of the Ryukyu Arc and its seafloors, and numerous other Asian countries, specifically by way of geological/tectonic investigation and natural radiation measurements. Also lately studying the paleoenvironment of the Ryukyu Arc, through the analysis of stalagmites found in limestone caves.


Professor Ryuichi Shinjo　Petrology, Mineralogy, and Geochemistry
Analyzes the microelements in and isotopic ratios of volcanic rocks found in the Ryukyu Arc and on the seafloor in the area to identify the generation mechanism of magma and the chemical features of the origin substance (mantle), and studies how they are associated with the formation of the island arc and seafloor.


Professor Kazuhiko Fujita　Marine Micropaleontology
Studies the ecology and paleoecology of foraminifera (family of star sand), a single-cell organism. Understanding the ecology of foraminifera helps to reconstruct the paleoenvironmental change in the oceans. Also studies the current global environmental issues concerning coral reefs (sea-level rise, eutrophication, and ocean acidification).
Research unit website: https://sites.google.com/site/reefforamslab/


Assistant Professor Asuka Sentoku　Paleontology
Research unit website: https://coral-time.blogspot.com/p/tigakukei.html