Influence of vegetation on aeolian sand transport rate from a backshore to a foredune at Hasaki, Japan

The influence of vegetation on aeolian sediment transport rate in the region from a backshore to a foredune was investigated at the Hasaki Coast in Japan, where an onshore wind was predominant and the creeping beach grasses Carex kobomugi and Calystegia soldanella were major species. The comparison of cross-shore distributions of the cross-shore component of aeolian sand transport rate with and without vegetation, which were estimated on the basis of the beach profile changes and a mass conservation equation, showed that the creeping grasses influenced the aeolian sand transport rate. The landward aeolian sand transport rate rapidly decreased landward from the seaward limit of vegetation when the grasses grew. The aeolian sand transport rate reduced by 95% with a vegetation cover of 28%. On the other hand, when the grasses were absent, the landward aeolian sand transport rate did not decrease near the seaward vegetation limit, but near the foot of the foredune.     

Palaeozoic and early Mesozoic fish faunas of the Japanese Islands

Abstract In recent years, many fish teeth and scales have been found from the Palaeozoic and Mesozoic age strata of the Japanese Islands. This study is a compilation of the Japanese fish record from the Palaeozoic and early Mesozoic age deposits. Based on the published and unpublished data, the fossil fishes from the Palaeozoic and Early Mesozoic of Japan can be classified into 27 genera and 33 species, that is, one species of Devonian placoderms, 19 species of Permian to Jurassic elasmobranchs, three species of Permian cochliodonts, seven species of Carboniferous to Permian petalodonts, and three species of Triassic to Jurassic osteichthyans.     

Cretaceous high-temperature rapid loading and unloading in the Abukuma metamorphic terrane, Japan

The Cretaceous Abukuma metamorphic terrane consists of the oceanic Gosaisyo Series overthrust onto the terrigenous Takanuki Series. Although the dominant mineralogy defines one of the classic areas of andalusite–sillimanite type progressive metamorphism, there are several lines of evidence suggesting an earlier higher-pressure (up to c . 12  kbar) history of the Takanuki Series and the nearby Gosaisyo Series. These are: (1) the occurrence of rare although widespread relic kyanite in sillimanite+K-feldspar zone-grade pelitic rocks; (2) the high grossular content of garnet interiors (up to c . 30  mol %) overgrown by Ca-poor rims ( c . 2  mol % grossular) in pelitic rocks containing Al₂SiO₅ minerals (sillimanite±relic kyanite±retrograde andalusite), plagioclase and quartz; (3) the occurrence of rutile as inclusions in garnet in pelitic rocks; and (4) the occurrence of relic corundum+almandine association in silica-poor and Al–Fe-rich rocks. Garnet in the Takanuki Series pelitic rocks commonly shows textural sector zoning and preserves growth zoning despite the high metamorphic grade, suggesting rapid changes in P–T  conditions and a relatively short duration of high-temperature conditions. Combined with radiometric dating, these observations suggest that the Abukuma sillimanite+K-feldspar zone-grade rocks underwent a clockwise P–T  path with very fast (>4  mm  y⁻¹) average burial and exhumation rates.     

应用压力感知胶片测定岩石连通空隙的分布

应用砂岩微观孔隙模型驱替实验技术,首次研究了张天渠油田长2油层在注水开发过程中的水驱油微观机理、孔隙结构与水驱油效率的关系.通过不同驱替压力、注入水倍数下的水驱油效率驱替实验证明油层孔隙结构的非均质性直接影响水驱油效果.分析了不同渗透率砂岩模型的驱替压力、注入倍数与驱油效率之间的相互关系以及残余水、残余油的分布特征,认为非活塞式驱油、绕流、卡断是残余油形成的主要原因.该实验研究为科学、合理地制定油田注采方案、提高水驱油效率提供了可借鉴的理论依据.     

Analysis on Soil Degradation Resulted From Human Activities Near City Area in China By Use of DMSP/OLS and Other Data

In order to study land use and cover changes (LUCC), especially urbanization accompanied soil degradation, authors used Asia DMSP/OLS data in 1992, Land Cover Data of Asia in 1992 and Global Assessment of Human Induced Soil Degradation (GLASOD, by ISRIC) in 1992, etc. In China the major type of soil degradation is water erosion, which is widely distributed especially in Loess Plateau and in Southeast and Southwest China and happened in forestland, grassland and arable land and mainly resulted from deforestation. The secondary type is wind erosion, which is mainly distributed in Northwest China and happened in arable land and grassland and was mainly caused by overgrazing. Chemical deterioration is mainly distributed in North and Northwest China and happened in paddy, arable land and grassland. Physical deterioration only concentrated in local area in North China and happened in arable land and paddy. Chemical and physical deterioration were resulted from unreasonable agricultural activity. From city to city + 200km with different distance away from city, different types and strength of human activities resulted in different types and distributions of soil degradation. In China human activity mainly concentrated within city+ 50km, therefore, accompanied soil degradation, such as chemical and physical deterioration, mainly happened near and around city.     

LUCC and Accompanied Soil Degradation in China from 1960''s to 1990''s

This paper tries to qualitatively analyze land use and cover changes (LUCC) and accompanied soil degradation in China, the data of World Atlas of Agriculture in 1969, Land Cover Data of Asia in 1992 and Global Assessment of Human Induced Soil Degradation in 1992, etc. have been used. From 1960' s to 1990's, the area of forestland had increased, arable land and paddy as well as grassland had significantly decreased in China. The major type of soil degradation is due to water erosion, which is widely distributed especially in Loess Plateau and in Southeast and Southwest China, this happened in forestland, grassland and arable land and mainly resulted from deforestation. The secondary type is wind erosion, which is mainly distributed in Northwest China, it happened in arable land and grassland and was caused by overgrazing. Chemical deterioration is distributed in North and Northwest China, which happened in paddy, arable land and grassland. Physical deterioration only concentrated in local area in North China, it happened in arable and paddy. Chemical and physical deteriora-tion mainly resulted from unreasonable activity. Because of different human activities, different LUCC and different natural conditions, the types and strength of soil degradation can be different.