1993 Fiscal Year Final Research Report Summary
Study on coral reef terraces of the Papua New Guinea coast--Establishment of Quaternary sea-level and tectonic history--
| Project/Area Number |
04041048
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| Research Category |
Grant-in-Aid for international Scientific Research
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| Allocation Type | Single-year Grants |
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| Section | Field Research |
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| Research Institution | Department of Geography |
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Principal Investigator |
OTA Yoko Department of Geography, Yokohama National University, Professor, 教育学部, 教授 (80017714)
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| Co-Investigator(Kenkyū-buntansha) |
PANDOLFI John Autralian Institute of Marine Sciences, 研究員
PILLANS Brad Department of Geology, Victoria University of Wellington, 地球科学, 講師
BERRYMAN Kelvin Earth Deformation Section, Institute of Geological and Nuclear Sciences, 核科学研究所, 研究員
CHAPPELL John Research School of Pacific Studies, Australian National University, 太平洋研究部, 教授
MATSUDA Shinya College of Education, University of the Ryukyus, 教育学部, 助教授 (30157317)
NAKAMORI Toru Institute of Geology and Paleontology, Tohoku University, 理学部, 助教授 (00192229)
OMURA Akio Department of Earth Sciences, Kanazawa University, 理学部, 教授 (70019488)
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| Project Period (FY) |
1992 – 1993
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| Keywords | Papua New Guinea / coral terrace / Quaternary sea level change / coseismic uplift / analysis of coral assemblage / U-series date / landslide / Quaternary tectonic movement |
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| Research Abstract |
This study aims to establish the late Quaternary sea level and tectonic history of the Huon Peninsula. Papua New Guinea, on the basis of detailed field observation, measurement, and sample treatment of coral reef terraces and underlying coral limestone, and to provide a standard for worldwide Quaternary chronology. Main results are as follows : 1. Large-scale geomorphological maps, which provide a fundamental information of coral reef terraces, are completed. 2. Repeated coseismic uplifts since ca. 53 ka were identified. Recurrence interval of large earthquakes associated with coseismic uplift is estimated to be roughly 1-5x10_3 years. Coseismic uplift is an important tectonic process in this rapidly uplifting coast. 3. Coseismic events are also estimated from paleolandslides, ages and distribution of which are tools for reconstruction of Paleoearthquakes. 4. Alpha-spectrometric and mass-spectrometric U-series dating determined the age of terrace II to be 33 ka and terrace III-a-upper to be 53 ka. Ages of all the terraces can be dated in a few years. 5. The water depth at the time of deposition of coral limestone was estimated from a comparison of modern and fossil coral assemblages. 6. These results together with terrace morphology enabled us to distinguish the regressive erosive terraces of coseismic origin from the transgressive constructional terraces which were formed in association with eustatic sea level rise. 7. Sea level curve between 70 ka and 30 ka is now revised. This revised curve is concordant with the results of oxygen isotope analysis obtained from deep sea cores.
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