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Volume 40 (1999 - 200･･･
- Issue 6 Pages 333-
- Issue 5 Pages 260-
- Issue 4 Pages 196-
- Issue 3 Pages 124-
- Issue 2 Pages 60-
- Issue 1 Pages 2-
Volume 40, Issue 3
Displaying 1-4 of 4 articles from this issue
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The Case of Fujiwara Mass, Sanbagawa Belt, Ehime Prefecture, SW JapanMakoto OHKOUCHI, Eiji OKUDA, Shigeru MIYAMURA1999 Volume 40 Issue 3 Pages 124-136
Published: August 10, 1999
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSWhen several joint systems are developed in rock masses, different deterioration conditions along those joints are often observed. This shows that those rock masses are different in stages of deterioration. As for the deterioration along the joint surface, the following process is recolgnized in general; from fresh part to weathering part, “fresh joint surface→brown pollution of joint surface→progresses of rock mass weathering”. From such phenomenon, brown pollution along joint surface may be regarded as a phenomenon of initial stage of weathering in fractured rock. In this paper, it is tried to grasp the deterioration tendency of joint by describing the brown pollution conditions on each joint surface. As a result, it was confirmed that the following joint deteriorated, “the joint that was formed by most late geological age tectonics”, “low angle joint distributed present or past groundwater surface neighborhood”.View full abstractDownload PDF (2190K) -
A Case Study in the Goroubi Drainage Basin in the Republic of Niger and Burkina FasoMasayuki NAKAHARA1999 Volume 40 Issue 3 Pages 137-148
Published: August 10, 1999
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSIn the Sahel region, the desertification is progressing with the influence of the climate change and the human being activity. The purpose of this investigation was to examine about the nature and the development of water resources for prevention of desertification.
The investigation area is the Goroubi drainage basin which extends over the Republic of Niger and Burkina Faso. Rain on the basin fall only in the rainy season from May to September and the annual precipitation is from 400 to 800mm. The river is a seasonal river and has flow only in the rainy season from June to early October. The annual flow rate is an average of 260 million cubic meter. The outflow form of the river is related with the size with drainage basin area. The groundwater can divide three unconfined aquifers. These aquifers exist in the basement complex of the Precambrian, in the Continental terminal formation of the Tertiary and the alluvial deposit of the Quaternary. This groundwater can be used through the year.
After estimating the water balance of the basin by the tank model, evapotranspiration is 66%, the river outflow is 5% and the underground penetration is 29%.
Effective usage of water resources is groundwater and dam storage water in the dry season, surface water and groundwater in the rainy season judging from the characteristic of water resources. Practically, these are construction of small dam and recharge dam, and well development for aquifers.View full abstractDownload PDF (3105K) -
Muneki MITAMURA, Shusakau YOSHIKAWA1999 Volume 40 Issue 3 Pages 149-158
Published: August 10, 1999
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSThe base depth distributions of 16 Quaternary marine clay beds (Ma-1 bed-Ma10 bed) in Osaka Plain were investigated statistically with 13 deep core drilling data.
The result of the investigation was that the base depth distribution of marine clay beds at these drilling site is explained by one-dimensional linear approximation with two coefficients, such as coefficients on thickness and vertical displacement, based on the OD-1 drilling data which is used as the standard stratigraphy in Osaka Plain. The standard probability curve on base depth of marine clay beds was created from probability distribution of each marine clay bed based on the OD-1 site with the linear relation. The standard curve revised appropriately with the two coefficients can represent the distribution of marine clay bed and geological structure in Osaka Plain.
This standard curve was preliminarily applied to the interpretation of a depth section of seismic reflection survey. The correlation of reflectors with basis of marine clay beds was attempted by analysis of the interrelation between reflectors and the standard curve revised with the two coefficients. The result of this attempt shows that this method is effective to investigate the activity of faults and three-dimensional distribution of marine clay beds.View full abstractDownload PDF (2461K) -
Kazuo KOSAKA, Takato TAKEMURA1999 Volume 40 Issue 3 Pages 159-165
Published: August 10, 1999
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSMicroscopic observation of intact granitoids reveals that different kinds of deformation microstructures within mineral grains result from various processes; deformation microstructures due to microcracking, microfaulting, microfolding, recovery and recrystallization. Some samples of intact granitoids exhibit only the undulose extinctions of quartz, plagioclase and biotite, while the others show abundant deformation microstructures, indicating that they contain many submicron-sized apertures in them. These deformation microstructures may be important as a possible cause of diffusivity and permeability of intact granitoids.
Water pathways within intact granitoids are detected in an experiment based on the capillarity of a KMnO4 solution. The EPMA images show that MnO2 is present on the polished surfaces of orthoclase, plagioclase and biotite grains after the experiment. MnO2 occurs in three ways : on grain-boundaries and/or intragranular cracks, in clustered submicron-sized pores, and dispersed on plagioclase and biotite grains. These modes of occurrence suggest that water pathways in intact granitoids are not only grain-boundaries and/or intragranular microcracks, but may also be mineral grains themselves that are permeated with submicron-sized apertures possibly having formed in deformation microstructures.
It follows that deformation microstructures should be most apparent at sites where abundant submicron-sized apertures are present. There are differences of deformation grade even in intact granitoids. This means that some intact granitoids include relatively few deformation microstructures, whereas others include many deformation microstructures. Since deformation microstructures are possible pathways for water, it is very likely that the diffusivity and permeability of a granitoid sample correlates with the nature and abundance of its included deformation microstructures. These microscopic observations and experiment suggest that deformation microstructures, as well as microcracks, should be studied much more thoroughly with regard to the diffusivity and permeability of intact granitoids.View full abstractDownload PDF (2776K)
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