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461.
New and detailed petrographic observations, mineral compositional data, and whole-rock vs glass compositional trends document
magma mixing in lavas erupted from Kilauea's lower east rift zone in 1960. Evidence includes the occurrence of heterogeneous
phenocryst assemblages, including resorbed and reversely zoned minerals in the lavas inferred to be hybrids. Calculations
suggest that this mixing, which is shown to have taken place within magma reservoirs recharged at the end of the 1955 eruption,
involved introduction of four different magmas. These magmas originated beneath Kilauea's summit and moved into the rift reservoirs
beginning 10 days after the eruption began. We used microprobe analyses of glass to calculate temperatures of liquids erupted
in 1955 and 1960. We then used the calculated proportions of stored and recharge components to estimate the temperature of
the recharge components, and found those temperatures to be consistent with the temperature of the same magmas as they appeared
at Kilauea's summit. Our studies reinforce conclusions reached in previous studies of Kilauea's magmatic plumbing. We infer
that magma enters shallow storage beneath Kilauea's summit and also moves laterally into the fluid core of the East rift zone.
During this process, if magmas of distinctive chemistry are present, they retain their chemical identity and the amount of
cooling is comparable for magma transported either upward or laterally to eruption sites. Intrusions within a few kilometers
of the surface cool and crystallize to produce fractionated magma. Magma mixing occurs both within bodies of previously fractionated
magma and when new magma intersects a preexisting reservoir. Magma is otherwise prevented from mixing, either by wall-rock
septa or by differing thermal and density characteristics of the successive magma batches.
Received: July 10, 1995 / Accepted: October 10, 1995 相似文献
462.
赵景波 《地球科学与环境学报》1998,20(3):46
西安东郊黄土中古土壤CaCO3和淋滤裂隙等的研究表明,使CaCO3发生迁移的水为重力水,CaCO3淀积层的顶界代表重力水淋溶亚带的底界,也是重力水发生突变的分界。薄膜水不具淋溶作用,也不会引起CaCO3的淀积。由CaCO3淀积深度可知,中更新世温湿期降水分配不均,雨季与旱季分明,增加的降水量主要集中在雨季降落;温湿期与冷干期的差别主要在雨季,旱季差异小。 相似文献
463.
1 Introduction Ultravioletradiationisahighlyactivecomponentofsolarspectrum .Ultravioletradiationhasdetrimentaleffectsonlivingthingsexposedtosunlight ,includingthedestructionofDNA ,proteinsandothermolecules(Harm ,1980 ) ,inhibitionofphotosynthesisandgrow… 相似文献
464.
465.
SAR影像仿真与水下地形反演的阻尼牛顿—行作用法 总被引:1,自引:0,他引:1
研究了浅海SAR影像仿真与水下地形反演的数值方法。将仿真与反演问题模型处理为相互独立的依赖于时间的非线性偏微分方程动力系统。使反演问题模型仅依赖于SAR影像灰度值,计算可一次性完成,计算过程中无须与正问题进行数据交互,在此基础上,提出了仿真与反演的一种新的一致性优化算法:阻尼牛顿-行作用法.数值实验结果表明,算法对SAR影像仿真问题具有高效、可靠、计算稳定的特征;对水下地形反演问题也有较强的数值稳定性和较高的计算精度。本文3个算例反演出的地形与实际地形之间的相关系数都优于0.72029. 相似文献
466.
Numerical Simulation for Refraction-Diffraction of Waves in Water of Slowly Varying Current and Topography 总被引:3,自引:0,他引:3
Hong Guangwen Feng Weibing Xia Qiyi Pan Shaohua
Professor Research Institute of Coastal Ocean Engineering Hohai University Xikang Road Nanjing
Senior Engineer Research Institute of Coastal Ocean Engineering Hohai University Xikang Road Nanjing 《中国海洋工程》1997,(4)
A new numerical finite difference iteration method for refraction-diffraction of waves in waterof slowly varying current and topography is developed in this paper.And corresponding theoretical modelincluding the dissipation term is briefly described,together with some analysis and comparison ofcomputational results of the model with measurements in a hydraulic scale model(Berkhoff et al.,1982).An example of practical use of the method is given,showing that the present model is useful to engineeringpractice. 相似文献
467.
1 .IntroductionAveraging has beenconsidered as anactive ,effective and precise methodinthe studyof fluid dy-namics ,andthe governing macroscopic variables like velocity are the averagingresults inthemselves .Consequently,for a special purpose ,the fluid m… 相似文献
468.
- A mild-slope equation for combined refraction and diffraction of random waves in the independent time current is derived using Kirby equation(1984). In the derivation, the frequency of random waves is represented based on the time series concept, by a typical frequency and its deviation part. Numerical results, compared with those of laboratory experiments, demonstrate that new set of irregular mild slope equation with current is of good adaptability. 相似文献
469.
Li Yucheng Zhang Ningchuan Professor Dalian University of Technology Dalian . Lecturer Dalian University of Technology Dalian 《中国海洋工程》1994,(3)
-A composite pipeline is defined as a pipeline system composed of one big pipe and one or several small pipes. Based on the theory of wave- current interaction and physical model test, the hydrodynamic characteristics of the submarine composite pipeline in wave-current coexisting field (both regular and irregular waves) are investigated. The so-called "modified diameter method" is used for analyzing the in-fine hydrodynamic coefficients of the composite pipeline, which are well related to KC number. The comparison of test data for regular and irregular waves shows that in the region of 90 > KC> 20, the results in these two cases can be unified. The effect of water depth is analyzed in details. The relationships between CD, CM and KC , which are based on the results of present research, may be used as a reference in engineering design. 相似文献
470.