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ID 15025
JaLCDOI
Sort Key
3
Title Alternative
Morphology and Anatomy of Holocene Raised Coral Reef Terraces in Kodakara Island, Tokara Islands, northwestern Pacific, Japan
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Author
Hamanaka, Nozomu
Nakashima, Yosuke
Hori, Nobuyuki
Okamoto, Takehiro
Ohashi, Tomoya
Adachi, Hiroshi
Abstract
Well-developed Holocene raised coral reef terraces are formed in Kodakara Island (29°13'N 129°19'E), Tokara Islands, northwestern Pacific, Japan. Detailed morphology and sedimentary structure of the raised reef terraces are observed by field survey through the terraces surface and core drillings. The Holocene raised reef in Kodakara Island are divided into three terraces (TI to III). The surface geo-biological facies and paleo-morphology such as spur and groove system or reef mounds are well preserved on these terraces. The raised coral reefs in Kodakara Island consist of reef flats and reef slopes. No lagoon formed in these terraces. On the raised reef surface, we observed five distinct reefal facies (S-f1-5). The platy and encrusting Acropora facies is the major constituent of the terrace surfaces. We obtained seven drilling cores (B1 to 7) from Terraces I and II along a transect in the southern part of the island. The thickness of the Holocene reef is more than 14m which is approximately equivalent to the Holocene reefs in the middle and southern Ryukyu Islands. Sedimentary structure consists of seven facies (C-f1-7: five reefal and two non-reefal facies). The drilling cores indicating the shallowing sequence at the upward of the cores which characterized by platy-encrusting Acropora facies overlying massive Porites, favid and/or encrusting-foliaceous coral facies. It may indicate the environmental change such as wave-energy gradients and turbidity during the reef development.
Keywords
Holocene
coral reef terrace
drilling
sedimentary structure
Tokara Islands
northwestern Pacific
Publication Title
Okayama University Earth Science Report
Published Date
2009-03-31
Volume
volume15
Issue
issue1
Publisher
岡山大学理学部地球科学教室
Publisher Alternative
Department of Earth Sciences, Faculty of Science, Okayama University
Start Page
33
End Page
65
ISSN
1340-7414
NCID
AN10506284
Content Type
Departmental Bulletin Paper
OAI-PMH Set
岡山大学
language
日本語
Copyright Holders
岡山大学地球科学研究報告編集委員会
File Version
publisher
Refereed
False
NAID
Eprints Journal Name
esr