排序方式： 共有18条查询结果，搜索用时 15 毫秒
1.
2.
JUNKO KOMATSUBARA OSAMU FUJIWARA KEITA TAKADA YUKI SAWAI THAN TIN AUNG TAKANOBU KAMATAKI 《Sedimentology》2008,55(6):1703-1716
Four sand units deposited by tsunamis and one sand unit deposited by storm surge(s) were identified in a muddy marsh succession in a narrow coastal lowland along the Pacific coast of central Japan. Tsunamis in ad 1498, 1605, 1707 and 1854 that were related to large subduction‐zone earthquakes along the Nankai Trough, and storm surges in 1680 and/or 1699 were responsible for the deposition of these sand units. These sand units are distinguished by lithofacies, sedimentary structures, grain‐size and mineral composition, and radiocarbon ages; their ages are supported by events in local historical records. The tsunami deposits in the study area are massive or parallel‐laminated sands, with associated intraclasts, gravels, draping mud layers and, rarely, a return‐flow subunit. The storm surge deposits are devoid of these characteristics, and are composed of groups of thin, current ripple‐laminated sand layers. The differences in sedimentary structures between the tsunami and storm surge deposits are attributed to the different characteristics of tsunami and storm waves. 相似文献
3.
4.
5.
6.
Plagioclase compositions vary from An0.1–2.5 to An32 with increasing grade in chlorite zone to oligoclase zone quartzofeldspathic schists, Franz Josef-Fox Glacier area, Southern Alps, New Zealand. This change is interrupted by the peristerite composition gap in rocks transitional between greenschist and amphibolite facies grade. Oligoclase (An20-24) and albite (An0.1–0.5) are found in biotite zone schists below the garnet isograd. With increasing grade, the plagioclase compositions outline the peristerite gap, which is asymmetric and narrows to compositions of An12 and An6 near the top of the garnet zone. In any one sample, oligoclase is the stable mineral in mica-rich layers above the garnet isograd, whereas albite and oligoclase exist in apparent textural equilibrium in adjacent quartz-plagioclase layers. The initial appearance of oligoclase in both layers results from the breakdown of epidote and possibly sphene. Carbonate is restricted to the quartz-plagioclase rich layers and probably accounts for the more sodic composition of oligoclase in these layers. The formation of more Ca-rich albite and more Na-rich oligoclase near the upper limit of the garnet zone coincides with the disappearance of carbonate and closure of the peristerite gap. Garnet appears to have only a localized effect on Ca-enrichment of plagioclase in mica-rich layers within the garnet zone. The Na-content of white mica increases sympathetically with increasing Ca-content of oligoclase and metamorphic grade. Comparison of the peristerite gap in the Franz Josef-Fox Glacier schists and schists of the same bulk composition in the Haast River area, 80 km to the S, indicates that oligoclase appears and epidote disappears at lower temperatures, and that the composition gap between coexisting albite and oligoclase is narrower in the Franz Josef-Fox Glacier area. It is suggested that a higher thermal gradient (38-40°C/km) and variations in Si/Al ordering during growth of the plagioclases between the two areas may account for these differences. In the Alpine schists the peristerite gap exists over a temperature and pressure interval of about 370-515°C and 5.5-7 kbar (550-700 MPa) PH2O. 相似文献
7.
8.
将中尺度非静力模式MM5中的积云参数化Grell方案作了改进，使它含有降水云的云水，即雨水含量，并用该模式对1998年6月29日08时-30日08时(北京时)和1998年7月1日08时-2日08时(北京时)发生在淮河流域的两次特大暴雨进行数值模拟研究，同时通过采用R-qr关系将TRMM／PR(Tropical Rainfall Measuring Mission/Precipitation Radar)得到的降水强度资料月计算出比含水量qr，然后用qv′＝qv qr取代原模式中的比湿qv。结果表明将TRMM／PR资料加入模式后，由于PR雷达具有较高的空间分辨率，能够很好地反映中小尺度系统的空间结构，能够使湿度值接近实际，缩短了中尺度系统的发展时间，使得模拟出来的降雨强度、雨量中心位置以及雨带形状更接近实况。 相似文献
9.
10.