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Volume 70 (2016)
- Issue 4 Pages 119-
- Issue 3 Pages 85-
- Issue 2 Pages 35-
- Issue 1 Pages 1-
Volume 70, Issue 2
Displaying 1-3 of 3 articles from this issue
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Review
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– Geology as a science of complex systems – part 3Tsunemasa SHIKIArticle type: Review
2016 Volume 70 Issue 2 Pages 35-44
Published: April 25, 2016
Released on J-STAGE: January 23, 2018
JOURNAL OPEN ACCESSAccording to the Takaetani’s “three-stage theory” scientific recognition should be carried out through three stages; 1 the “phenomenological stage”, 2 the “substantial stage” and, 3 the “essential stage”. This theory is concerned originally with non-complex systems but can also be adapted to the study of complex systems also. A few examples are, 1: The contrary tendency problem among decrease of grain sizes and compositional maturity of the Permian and Triassic sandstones in the Maizuru belt was solved by investigation of the inner “substantial” structure of the stones. The grain sizes of the constituent minerals of the sediments were controlled essentially by the characteristics of substantial constituent crystals. 2: Mo content distribution in sediments of Lake Shinji researched by Yasumatsu (1973) provides another example showing the importance of trance-level investigation. Mo is concentrated substantially in fine clay-size sediments around a river mouth. 3: As and Pb were found in the water discharge tunnel which was planned to strengthen the discharge ability of Amagase dam. The source and the substantial state of the elements in the samples was not checked by the relevant government department. Therefore city offices could not offer any exact information about environmental pollution to citizens. These examples show the importance of substantial studies. The combined consideration of two concepts, the “system formation level concept”and the “three stages of recognition theory” is a strategically effective way to understand various complex systems.View full abstractDownload PDF (1326K)
Research Article
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Naoki NEMOTO, Kentaro SAEKI, Takashi HISAJIMA, Tsutomu YAMADA, Koji MI ...Article type: Research Article
2016 Volume 70 Issue 2 Pages 45-64
Published: April 25, 2016
Released on J-STAGE: January 23, 2018
JOURNAL OPEN ACCESSDuring Messinian Period, evaporates were widely deposited in Paleo-Mediterranean Sea. The Sorbas Basin, southeastern Spain, is situated near the Strait of Gibralter between the Atlantic Ocean and the Mediterranean Sea, and was a part of the Paleo-Mediterranean Sea. The changes of both planktic and benthic foraminiferal assemblages from the Abad Member, Turre Formation distributed in the Sorbas Basin were investigated to reconstruct long-term paleoenvironmental change in this basin during early Messinian Period.
The occurrence of Globorotalia miotumida from the basal part of the Abad Member and disappearance of this species in the middle part of this member indicate that the base of this member is younger than 7.246Ma and lower half of this member is older than 6.506Ma. The coiling direction of Neogloboquadrina acostaensis suggests that the most of the Abad Member is older than 6.337Ma.
On the basis of faunal change of planktic foraminifers, following surface conditions alternatively occurred during the deposition of the Abad Member; warm and shallow mixing layer, cool and shallow mixinglayer, and cool and deep mixing layer. This environmental change might represent the cyclic change of the surface water condition proposed by Sierro et al. (2003). Salinity of the surface water increased during the deposition of the Abad Member. The bottom environment was also reconstructed on the basis of benthic foraminifers. In long term, the bottom condition was controlled by the decrease of the paleo-water depth and disoxygenation of deep water probably caused by uplifting of the Sorbas Basin and the stagnation of bottom water, respectively.View full abstractDownload PDF (2773K) -
Takahiko SAKAMOTO, Keisuke TANIGUCHI, Fujio MASUDAArticle type: Research Article
2016 Volume 70 Issue 2 Pages 65-81
Published: April 25, 2016
Released on J-STAGE: January 23, 2018
JOURNAL OPEN ACCESSThere were three flooding events over a period of five years in the lower reach of the Kizugawa River, Japan. Bedforms were formed in the flood channel of the Kizugawa River during these flood events. The bedforms led to rearrangements from the upper stream to the lower stream reach, and the following structures appeared in order: inner bank ponds, microdeltas, lingoid-type dunes, parallel-type dunes, lunatetype dunes, barchans, lingoid-type ripples, and parallel-type ripples. The orders of rearranged bedforms have the same sequences through some bedforms are occasionally missing. During the first flooding lingoid ripples were formed on the parallel ripples. In the second flooding, parallel dunes piled up on the parallel ripples. The smaller bedforms are distributed at the lower reach and the larger bedforms are distributed at the upper reach. These facts suggest that the bedforms were formed from the lower reach to the upper reach with rising water level.Except for these bedforms, microdelta antidune and sand patches were also formed. Microdelta was formed at the falling stage of water level. Because of a little incline of the ground surface on the northern side, the water depth, current velocity, and sand supply decreased on the southern side of the ground; as a result, dunes were not developed and ripples were spread.View full abstractDownload PDF (2315K)
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