Mid-pacific mountains revisited   总被引：1，自引：0，他引：1  

Loren W. Kroenke  James N. Kellogg  Kenji Nemoto 《Geo-Marine Letters》1985,5(2):77-81

The Mid-Pacific Mountains are guyots whose volcanic pedestals have been constructed on a broad basement plateau, the flanks of which are downfaulted. Edifice construction may have been controlled by an orthogonal system of intersecting faults trending roughly ENE and NNW. Low amplitude gravity anomalies observed over the Mid-Pacific Mountains indicate complete Airy-Heiskanen isostatic compensation, crustal thickening, and eruption on thin elastic lithosphere. Tholeiites of the Mid-Pacific Mountains resemble lavas of Iceland and the Galapagos Islands. The orthogonal fault system, low gravity anomalies, and lava chemistry of the Mid-Pacific Mountains can be explained by eruption on or near a great ENE-trending rift system.  相似文献   

Phytoplankton distribution in a frontal region of Tokyo Bay,Japan in November 1985     

Myung-Soo Han  Ken Furuya  Takahisa Nemoto 《Journal of Oceanography》1989,45(5):301-309

Phytoplankton distribution in a frontal region of Tokyo Bay was investigated in relation to hydrography in November 1985. The frontal region was observed from the central to the mouth area of the bay and consisted of a series of fine scale discontinuities of salinity and temperature. Among them the Kenzaki offshore front (KOF) and the Yokosuka inshore front (YIF) were most prominent in terms of the duration and the magnitudes of the hydrographic gaps. Three major phytoplankton assemblages were observed: (A) neritic and offshore diatoms in the mouth area of Tokyo Bay, (B) a diatomLeptocylindrus danicus and dinoflagellates in the central area, and (C) bloom forming cryptophyceans, dinoflagellates andL. danicus from the inner Tokyo Bay. The KOF was an approximate boundary of the outside assemblage (A) and the intermediate population (B), and the YIF was that of (B) and the inner bay population (C). Species changes across the fronts were rather gradual in the KOF making a strong contrast to distinct jumps in temperature, salinity,in vivo chlorophyll fluorescence and nitrate plus nitrite. An outward surface flow of the inside population along the western coast off Yokosuka was detected.  相似文献   

Integumental sensilla of diagnostic value in euphausiids     

John Mauchline  Takahisa Nemoto 《Journal of Oceanography》1977,33(5):283-289

Two types of integumental compound sense organs are described in 48 of the 86 known species of euphausiids. The first occurs in the dorsal regions of the abdominal segments, especially the fourth and fifth. They consist of paired rows of short peglike setae that appear to have bifid endings and are thus probably chemoreceptors. The second type is a compound organ present in the median dorsal anterior region of the carapace. It is usually located in the apical region of a keel in front of cervical groove. Its form is different in each species and so it can be used as a diagnostic feature to identify damaged euphausiids and females where the male copulatory organ (petasma) is the principal character used to identify the species.  相似文献   

Hydraulic model tests for evaluating sediment control function with a grid-type Sabo dam in mountainous torrents   总被引：2，自引：0，他引：2  

Takahiro ITOH  Shigeo HORIUCHI  Takahisa MIZUYAMA  Kazuhiko KAITSUKA 《国际泥沙研究》2013,28(4):511-522

There are two kinds of Sabo dams in order to control sediment transport by debris flow and flash floods in mountainous area, which are closed and open-type＇s dams. In Japan, open-type＇s Sabo dams are constructed taking into account the continuity of sediment routing from upstream to downstream reach in a basin. A plan to construct a 20 m high grid-type Sabo dam which can capture a sediment volume of 400,000 m3 is proposed in the Amahata river basin in Japan. Hydraulic model tests are conducted to decide on the section for a dam （Section A, B） and the grid size such as clearance of vertical/horizontal bars for evaluating the plan. Several runs of flume tests are conducted and the sediment control function of the Sabo darn is discussed using several experimental data such as dimensionless sediment runoff rate from Sabo dam, temporal changes of bed profile and mean diameter and so on. It was found that sediment deposition in sediment storage area of Sabo dam was affected by curved channel, and that next the grid size of steel bars and thirdly the section of a dam was able to capture sediment in storage area of Sabo dam. Sediment was controlled well in the section B and in the grid size of 1.0×d95, and the problems related to sediment runoffafter sediment capturing in Sabo dam are pointed out.  相似文献