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Volume 34 (1995)
- Issue 5 Pages 335-
- Issue 4 Pages 279-
- Issue 3 Pages 125-
- Issue 2 Pages 65-
- Issue 1 Pages 1-
Volume 34, Issue 2
Displaying 1-6 of 6 articles from this issue
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Hiroyuki Ogura, Shusaku Yoshikawa, Shomei Okada, Yasuo Yamamoto1995 Volume 34 Issue 2 Pages 65-73
Published: May 31, 1995
Released on J-STAGE: August 21, 2009
JOURNAL FREE ACCESSMagnetic susceptibility of tephra and brown-soil beds distributed at the foot of Mt. Daisen was measured at seven sites to examine its applicability to correlate tephra beds. The measurements show that the susceptibility values of each correlatable tephra bed are within a narrow range, regardless of the site. Each tephra bed has a characteristic pattern of vertical susceptibility change, which is useful for detailed correlation between tephra beds, and also between invisible horizons within the tephra beds of almost homogeneous lithofacies. In brown-soil beds, visually indistinct horizons of volcanic-sand-type tephra fall could be identified at the remarkable peaks of susceptibility, by tracing the peaks horizontally. Magnetic susceptibility profiles measured along vertical sections of tephra and brown-soil beds have a high potential of application to tephrostratigraphy and tephrochronology.View full abstractDownload PDF (1022K) -
Takashi Azuma1995 Volume 34 Issue 2 Pages 75-89
Published: May 31, 1995
Released on J-STAGE: August 21, 2009
JOURNAL FREE ACCESSLate Quaternary terraces on Tsugaru Peninsula, northernmost Honshu, are divided into five levels (Terrace I-V), and each terrace is of marine (m) and fluvial (f) origin. Terrace IIIm, which is distributed most widely and is overlain by the Toya ash (100-130ka), was formed during the last interglacial maximum of ca.124ka (oxygen isotope sub-stage 5e). The height of the former shoreline of Terrace IIIm reaches 40m above sea level (average uplift rate is ca.0.3m/ka), and its height distribution shows a warping with short wave-length (ca.3km) on the north and a warping with about 30km wave-length on the east. Two active fault systems, running north-south, bound the plains area from the central mountains and dislocate Terrace Im, IIf on the west and IIIm on the east. The fault system on the west is composed of a main synthetic fault, represented by a west-facing flexural scarp and an antithetic fault which has a range-facing scarplet. The degree of fault activity is class B-C (slip rate; 0.08-0.15m/ka) for the synthetic fault and C (<0.1m/ka) for the antithetic fault. The slip rate of flexural scarp on the east is larger (0.14-0.30m/ka) than on the west. These faults are estimated to be reverse faults which have been produced under a stress field with E-W compression. Late Quaternary terraces have been deformed significantly in the eastern part and the northern central part of the peninsula where Pliocene sediments are thickly deposited.View full abstractDownload PDF (2265K) -
Takashi Sase, Katsuhiro Inoue, Yi Fei Zhang1995 Volume 34 Issue 2 Pages 91-100
Published: May 31, 1995
Released on J-STAGE: August 21, 2009
JOURNAL FREE ACCESSWe clarified the Late Pleistocene and Holocene vegetation and climatic changes by phytolith analysis of accumulated tephras (aeolian deposits including a eolian dust) after the fall of Toya Ash on the foot of Mt. Iwate. Five cold stages (KS-a-KS-e) were distinguished by a relatively high frequency of Pooideae phytolith (Festucoid) and coniferous phytolith. A tephra stratigraphy and chronology suggests that the KS-a to KS-d cold stages between the White Pumice (Towada Pumice Flow: ca.15ka) and the Aso-4 Ash (70-90ka) are correlated with those in the Last Glacial and that the KS-e cold stage beneath Aso-4 Ash corresponds with that in the Last Interglacial. A dominance of Pooideae in the KS-a and KS-d cold stages indicates a very cold climate. The occurrence of coniferous forests in the KS-b, KS-c and KS-d suggests a humid condition. Climate in the Ks-e cold stage is not colder than that in later cold stages because of the relatively small amount of Festucoid. Since the Last Interglacial after the fall of Toya Ash, the following three periods are established based on paleoenvironments reconstructed by vegetation history, periglacial phenomena, involution, and a eolian dust influx: 1) Toya Ash-K3S: a cool or cold period with humid climate and characterized by a low a eolian dust influx in the late Last Interglacial and marked deposition of primary and secondary tephras; 2) K3S-the top of the Shibutami Volcanic Ash: a very cold or cold period with humid or dry climate, characterized by a high a eolian dust influx, crack development in a eolian dust horizons, and intense involution corresponding to the Last Glacial age; 3) the Wakare Volcanic Ash (13ka-modern): a cold to cool period and humid climate, characterized by a low a eolian dust influx and humus accumulation.View full abstractDownload PDF (1185K) -
H. Sato1995 Volume 34 Issue 2 Pages 101-106
Published: May 31, 1995
Released on J-STAGE: August 21, 2009
JOURNAL FREE ACCESS -
Takahiro Miyauchi1995 Volume 34 Issue 2 Pages 107-120
Published: May 31, 1995
Released on J-STAGE: August 21, 2009
JOURNAL FREE ACCESSThe Marine Quaternary chronostratigraphy established in Italy has been the standard in the Mediterranean area since the end of the 19th century. But the discrepancies in the Quaternary Stages defined by different geologists are often troubling and the original meanings of the terms have sometimes been changed in Italy. This paper briefly reviews recent trends in Italian Quaternary chronostratigraphy, in particular those associated with marine terrace formation.
The “Holocene” is exceptionally adopted as a Stage in the Holocene series so as not to cause confusion. In the upper Pleistocene series, the universally known “Tyrrhenian” is identified on the basis of transgressive sediments bearing a molluscan fauna, Strombus bubonius. These sediments, which underlie a well-developed marine terrace, are correlated with the last interglacial epoch, the oxygen isotope substage 5e. Only the “Crotonian” is accepted as occurring in the middle Pleistocene series, which is defined as transgressive biocalcarenite and is correlated to the oxygen isotope stages 7, 9, and 11. The Superstage “Selinuntian”, composed of the three Stages “Santernian, Emilian and Sicilian”, is reliably established in the lower Pleistocene series based on the biochronostratigraphy. The “Santernian” is identified by the appearance of a molluscan fauna Arctica islandica and a species of ostracoda Cytheropteron testudo; the “Emilian” by the benthic foraminifera Hyalinea baltica; and the “Sicilian” by the planktonic foraminifera Grobolotalia truncatulinoides excelsa (Fig. 2).
Chronounit “Stages” must be carefully defined and redefined with reference to other Quaternary studies according to the divisional rule of chronostratigraphy, to avoid further problems with terminology.View full abstractDownload PDF (2790K) -
1995 Volume 34 Issue 2 Pages 124
Published: 1995
Released on J-STAGE: August 21, 2009
JOURNAL FREE ACCESSDownload PDF (59K)
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