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Volume 32 (1993)
- Issue 5 Pages 245-
- Issue 4 Pages 195-
- Issue 3 Pages 129-
- Issue 2 Pages 61-
- Issue 1 Pages 1-
Volume 32, Issue 1
Displaying 1-4 of 4 articles from this issue
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Kiyoshi Fujimoto1993 Volume 32 Issue 1 Pages 1-12
Published: February 27, 1993
Released on J-STAGE: August 21, 2009
JOURNAL FREE ACCESSIn order to reconstruct late Holocene sea-level changes, this paper clarifies the late Holocene relative sea-level changes by using FeS2 content analysis and radiocarbon dating and discusses the elimination of the influence of uplift on a small valley bottom plain facing Nanao-nishi Bay, which is a small inner bay situated on the east coast of the Noto Peninsula, Central Japan. A small valley bottom plain facing a small inner bay provides a suitable site for the tracing of late Holocene sea-level changes. The Noto Peninsula is considered an upheaval area because it is fringed by Pleistocene and Holocene marine terraces. The uplift rate of the Nanao-nishi Bay area inferred from the altitude of the marine terraces is relatively small in the Noto Peninsula.
Several types of geologic and geomorphic evidence, such as irregularity in the sedimentation rate of marine deposits, trace fossils of boring shells, and Holocene marine terraces indicate the possibility that three intermittent uplift events which may have followed earthquakes occurred in late Holocene time. The three events, named event 1 to event 3 in order from the most recent, probably occurred 500-1, 600yrs BP, 1, 600-2, 200yrs BP and 3, 300-4, 000yrs BP respectively. It is possible that the displacement in each event was 0.2-0.9m uplift. The estimation was based on the average occurrence interval of the events, the average uplift rate inferred from the height of the Last Interglacial marine terraces, and the empirical rule that displacement in each earthquake lies between half and double the average displacement. On the basis of the irregularity of the sedimentation rate of marine deposits, the possibility that the displacement in event 3 may have been 0.9m uplift is pointed out.
It is possible that the elimination of the influence of uplift, estimated as outlined above, leads to reconstruction of the late Holocene sea-level changes, indicating that the highest sea-level in the Holocene occurred about 3, 500yrs BP.View full abstractDownload PDF (1842K) -
Keiko Taguchi1993 Volume 32 Issue 1 Pages 13-29
Published: February 27, 1993
Released on J-STAGE: August 21, 2009
JOURNAL FREE ACCESSIzu Peninsula is situated at the northern tip of the Philippine Sea Plate, which is being subducted beneath the Japanese island of Honshu at the Suruga Trough along the west coast of the Peninsula. Because the tectonic setting is different from other areas, the record of coastal uplift in the Quaternary might also be expected to differ.
The purpose of this paper is to clarify Holocene relative sea-level change and Holocene tectonic movement in the Izu Peninsula. These are estimated on the basis of analysis of sedimentary facies, molluscs and diatoms, 14C dates of wood and peat samples, and examination of emergent coastal landforms.
Peat-coring and core boring by mechanized drilling were carried out in four coastal lowlands, at Ito, Shimoda, Toji and Nishina.
At Ito, the apparent marine limit is about 0m amsl. Radiocarbon dates of Holocene deposits range from ca. 9, 000yrs BP at the basal part to ca. 4, 000yrs BP, on the peat above the marine deposits. At this locality, marine deposits are probably truncated by fluvial erosion; the original marine limit is estimated to be slightly above the present sea level, and younger than ca. 4, 000yrs BP. At Shimoda, the upper limit of marine deposits is 1.4m amsl, with 14C age of ca. 2, 400yrs BP. This is similar to the data obtained from the Okamo and Kisami areas (Ota et al., 1986).
Examination of emergent coastal landforms indicates that they can be divided into two zones. The height of the upper zone is +2.5-+3.0m, and that of the lower zone is +1.5-+2.0m. These heights indicate that there were two discontinuous uplifts.
The data imply that the upper limit of the marine deposits is significantly younger than in other areas, where the postglacial transgression culminated at ca. 5, 000-7, 000yrs BP, and that the study area subsided until ca. 2, 000-3, 000yrs BP, followed by a slight, probably episodic uplift.View full abstractDownload PDF (2248K) -
Jota Kiyonaga1993 Volume 32 Issue 1 Pages 31-40
Published: February 27, 1993
Released on J-STAGE: August 21, 2009
JOURNAL FREE ACCESSThe vegetation history since ca. 5, 800yrs BP around the lowland along the River Uta in the western part of Sagami Plain, central Japan, is reconstructed based on pollen analysis. From 5, 800-3, 600yrs BP, summer-green forest was dominant. The main arboreal taxa of that forest were Quercus subgen. Lepidobalanus and Celtis-Aphananthe from 5, 800-5, 100yrs BP, and Lepidobalanus and Castanea crenata from 5, 100-3, 600yrs BP. Since 5, 100yrs BP the area of laurel forest, which was mainly composed of Quercus subgen. Cyclobalanopsis and Cryptomeria japonica forest has been on the increase, reaching its maximum during 3, 600-1, 200yrs BP. The most recent 1, 200-year period has been characterized by a predominance of Pinus forest. The vegetation history reconstructed by this study is generally cosistent with previous palynological studies based on samples which were derived from Sagami Plain. The discrepancies are, however, that around this lowland the laurel forest has not been mainly composed of Pasania-Castanopsis, which was one of the main elements of the laurel forest at ca. 3, 500yrs BP in the southeastern part of Sagami Plain. The predominance of Castanea crenata during ca. 5, 000-ca. 3, 500yrs BP and three stages of the human impact on vegetation after ca. 2, 000yrs BP, which are observed in Kanto Plain, was also confirmed in this region.View full abstractDownload PDF (1189K) -
The Trace of Liquefaction (Sand Eruption) Caused by Earthquake at Hasekhoji Sites in Kamakura, JapanS. Uemoto, T. Ohkouchi, A. Sangawa, H. Yamazaki, E. Tsukuda, Y. Matsus ...1993 Volume 32 Issue 1 Pages 41-45
Published: February 27, 1993
Released on J-STAGE: August 21, 2009
JOURNAL FREE ACCESS
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