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| Northern Antarctic Peninsula Region including South Shetland Islands has formed the Arc-Trench system since late Paleozoic. The system is characterized by the subduction of oceanic plate beneath the Antarctic Peninsula, Cenozoic South Shetland Arc, Mesozoic separation of Gondwanaland and collision of mid-oceanic ridge with trench. The region, therefore, provides an excellent opportunity for studying geologic processes and tectonic evolution in active plate margin. This study aims at verifying geological evolution and tectonics of the South Shetland Arc-Trench system in Northern Antarctic Peninsula Region since late Paleozoic. |
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In order to understand characteristics of igneous activity and development of sedimentary basins in the northern Antarctic Peninsula since late Paleozoic, the following four topics have been studied.
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Petrography and geochemistry of volcanic nunataks in the southwestern King George Island
Early Cretaceous volcanic activity in the Barton Peninsula, King George Island
Sedimentary process and environment of the Byers Formation in Livingston Island
Geochemistry of intrusive rocks in the Hurd Peninsula, Livingston Island
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1. Most nunataks are thought to have been paleo-volcanic centers of King George Island. The volcanic rocks from the nunataks are subalkaline basaltic andesites to andesites, and mostly show Medium K and tholeiite-series geochemical nature. Predominant occurrence of tholeiite-series volcanic rocks as well as trace element geochemical features indicate that the volcanic rocks in King George Island were formed in a comparatively primitive island arc environment.
2. Ar-Ar age determination of basaltic andesites in the lowermost sequence of the Barton Peninsula indicates early Cretaceous volcanic activity in King George Island.
3. Dark gray mudstone is dominant in the President Beaches Formation of the Byers Peninsula, Livingston Island. The formation is considered to have been formed in slope basin. Sandstone layers consist of typical and reworked turbidites.
4. The Intrusive rocks of the Hurd Peninsula in Livingston Island consist of granitic rocks and mafic dikes, and their SiO2 contents range from 46 to 57 wt%. Major and trace element compositions suggest fractionation from different parental magmas between granitic rocks and mafic dikes. The tholeiitic nature of the intrusive rocks indicate that they were formed near volcanic front during subduction of oceanic plate. |
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| The study on formation mechanism of sedimentary basins as well as on the origin of igneous activity and mineralization in the South Shetland arc-trench system will play an important role for the clarification of geological evolution of West Antarctica. The formation of sedimentary basins and deposition of sediments are critical factors for inferring the distribution and quantity of submarine mineral resources. These results will be very useful for studying geological evolution of the Weddell Sea region and Antarctic Peninsula. |
Research Activities > Major Topics > Terrestrial Geology and Environment
