Fossil fluid reservoir beneath a duplex fault structure within the Central Range of Taiwan: implications for fluid leakage and lubrication during earthquake rupturing process     

Yu-Chang Chan  Kazuaki Okamoto  Tzen-Fu Yui  Yoshiyuki Iizuka  Hao-Tsu Chu 《地学学报》2005,17(6):493-499

In order to understand the kinematics which likely facilitated the speedy rupturing process of the 1999 Mw 7.6 Taiwan Chi-Chi earthquake, we examined exposed rocks in the Taiwan Slate belt, where the pressure and temperature conditions most resembled the hypocentre of the Chi-Chi earthquake, i.e. sub-greenschist facies. Field observations and composition analyses of the silicified vein-rich zones beneath the duplex structure suggest that impermeable slate layers may serve as cap rocks for confining deep-seated fluids. These fluids most likely come from the Taiwan metamorphic complex at deeper depths by the dehydration and decarbonation reactions (or partial melting). In addition, the gouge zone of a link fault above the detachment also indicates the presence of overpressured fluids during faulting. It is probable that episodic leakage of the confined fluid reservoirs may provide essential fluids for fault lubrication during earthquake ruptures.  相似文献   

Spatial variability of chemical tracers in surface snow along the traverse route from the coast to 1000 km inland at east Dronning Maud Land, Antarctica   总被引：1，自引：0，他引：1  

Toshitaka Suzuki  Yoshinori Iizuka  Teruo Furukawa  Kenichi Matsuoka  Kokichi Kamiyama  Okitsugu Watanabe 《极地研究(英文版)》2003,14(1)

1　IntroductionAntarcticicesheetisaburialgroundforatmosphericdeposition .Sincethereiscon tinuousinteractionbetweentheicesheetandtheatmosphere,variousatmosphericsub stancesareinjectedtotheicesheetsequentiallyintimeandspace.Therefore,verticalanalysesoftheicesheetprovideuswithinformationaboutpastclimaticchange (Delmas1 992 ;LegrandandMayewski 1 997)andhorizontalanalysesoftheicesheetprovideuswithknowledgeregardinglong rangetransportofairbornematerials (Kamiyamaetal.1 989;KreutzandMayewski 1 999)…  相似文献   

Simulations of an isotopic fractionation by freezing in an open system     

Yoshinori Iizuka 《极地研究(英文版)》2003,14(1)

1　IntroductionBasaliceofglaciersandicesheetshasbeenwidelystudiedtounderstandtheinacces sibleice bedinterface (e.g.,Lawson 1 979;Gowetal.1 979;Knight 1 994;HubbardandSharp 1 995 ,Souchez1 988) .Useofstableisotopesofbasaliceisasuperiormethodtodeterminewhetherthebasalicewasformedbymelt refreezingornon meltingattheinlandbaseofglaciersandicesheets.Inatheoreticalstudyofstableisotopes,JouzelandSouchez ( 1 982 )showedthatforaclosedsystem ,wherenowaterisinputoroutput,theslopegradientdefinedbyδ18O…  相似文献   

Deep seismic surveys off southern Honshu,Japan, and earthquake prediction     

Masami Hayakawa  Susumu Iizuka 《Proceedings of the Geologists' Association. Geologists' Association》1982,93(2):195-200

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Origin of high-magnesian andesites in the Setouchi volcanic belt,southwest Japan,II. Melting phase relations at high pressures     

Yoshiyuki Tatsumi 《Earth and Planetary Science Letters》1982,60(2):305-317

Melting phase relations of an augite-olivine high-magnesian andesite and an augite-olivine basalt from the Miocene Setouchi volcanic belt in southwest Japan have been studied under water-saturated, water-undersaturated and under anhydrous conditions. Both the andesite and the basalt are characterized by low FeO*/MgO ratios (0.86 and 0.76 in weight, respectively) and qualify as primary magmas derived from the upper mantle.The andesite melt coexists with olivine, orthopyroxene and clinopyroxene at 15 kbar and 1030°C under water-saturated conditions, and at 10 kbar and 1070°C under water-undersaturated conditions (7 wt.% H₂O in the melt). The basalt-melt also coexists with the above three phases at 11 kbar and 1305°C under anhydrous conditions, and at 15 kbar and 1205°C in the presence of 4 wt.% water.Present studies indicate that high-magnesian andesite magmas may be produced even under water-undersaturated conditions by partial melting of mantle peridotite. It is suggested that two types of high-magnesian andesites in the Setouchi volcanic belt (augite-olivine and bronzite-olivine andesites) were produced by different degrees of partial melting; augite-olivine andesite magmas, whose mantle residual is lherzolite, were formed by lower degrees of partial melting than bronzite-olivine andesite magmas, which coexist with harzburgite. The basalt magmas, which were often extruded in close proximity to the high-magnesian andesite magmas, are not partial melting products of a mantle peridotite which had previously melted to yield high-magnesian andesite magmas.  相似文献   

Alpha-emitting thorium isotopes in northwest Pacific deep waters     

Yoshiyuki Nozaki  Yoshio Horibe 《Earth and Planetary Science Letters》1983,65(1):39-50

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Melting experiments on a high-magnesian andesite   总被引：1，自引：0，他引：1  

Yoshiyuki Tatsumi 《Earth and Planetary Science Letters》1981,54(2):357-365

Melting experiments were conducted on a high-magnesian bronzite olivine andesite (Teraga-Ike andesite) which is considered to be a primary andesite. The high-magnesian andesite magma is in equilibrium with both olivine and orthopyroxene at about 15.5 kbar and 1080°C under H₂O-saturated conditions and at lower pressure and higher temperature under H₂O-undersaturated conditions. This suggests that high-magnesian andesites could be generated by the partial melting of upper mantle peridotite containing a small amount of H₂O.  相似文献   

太平洋西北海域海水中钇与稀土元素的地球化学   总被引：1，自引：0，他引：1  

张劲  天川裕史  野崎羲行 《海洋与湖沼》1996,27(1):51-59

海水样品是在东京大学海洋研究所科学考察船（淡青丸KT）93－14次航海期间，于1993年9月12日在日本伊豆-小笠原海沟海域（29°05′N，142°51′E，水深9500m）采集的。采用化学萃取-反萃取分离法并结合等离子质谱仪，对样品进行分析研究。结果表明，海水中重稀土相对于轻稀土富集，相对于重稀土和轻稀土来说，中稀土有一定程度的亏损。钇浓度从海水表面随深度的增加而逐渐增加，与稀土元素一样在海水断面上呈营养盐型分布。同时还发现Ho是稀土中与Y相关性最好的元素，并指出Ho／Y的浓度比同样可以用来示踪海洋中水团的移动。  相似文献   

Stability considerations of an anchor dragged in noncohesive sea bed     

Tamaki Ura  Yoshiyuki Yamamoto 《Applied Ocean Research》1979,1(1):43-50

The maximum holding power and the stability of stockless anchors dragged in non-cohesive media are considered. Forces and moments acting on each structural element of the anchor, such as flukes, shank and stabilizing fins, were investigated experimentally, and the results are given in formulae.The maximum holding power of an anchor depends upon its configuration in the sea bed. Considering force resultants and moments acting on all the structural elements, equilibrium equations are formulated and the configuration of a dragged anchor and its maximum holding power can be determined by solving these equations. If its equilibrium configuration cannot be determined under the surface of the sea bed, the dragged anchor will turn over as soon as the flukes come out of the bed. This instability will be called lifting-up.Instability phenomena caused by turning around the shank are analysed by considering the resulting moments acting on the anchor in a disturbed condition from the equilibrium configuration. From the results, stability conditions for lifting-up and turning are proposed for the anchor dragged in noncohesive media, and an anchor of absolute-roll-stability is realized by attaching a pair of proper stabilizing fins.  相似文献   

Ecosystem shift resulting from loss of eelgrass and other submerged aquatic vegetation in two estuarine lagoons, Lake Nakaumi and Lake Shinji, Japan     

Masumi Yamamuro  Jun-Ichi Hiratsuka  Yu Ishitobi  Shinya Hosokawa  Yoshiyuki Nakamura 《Journal of Oceanography》2006,62(4):551-558

Zostera marina L. was intensively harvested until the early 1950s in Lake Nakaumi, a eutrophic estuarine lagoon. We have estimated the amount of nitrogen (N) and phosphorus (P) removed from the lagoon through Z. marina harvesting. Lake Nakaumi lies in Tottori and Shimane prefectures, and the annual harvest of Z. marina in the late 1940s in Tottori was recorded as at least 56,250 t wet weight. The nutrient content of 56,250 t of Z. marina was calculated to be 61.9 t of N and 12.9 t of P, which is equivalent to 5.3% and 11%, respectively, of present annual nutrient loads to the lake. The nutrients formerly used by Z. marina were likely used by phytoplankton after the Z. marina started to decline in the mid-1950s at Lake Nakaumi. This shift in the chief primary producer, from benthic macrophytes to phytoplankton, caused a subsequent shift in secondary producers. Benthic fish and crustacean populations decreased and the non-commercial filter-feeding bivalve, Musculus senhausia, increased in Lake Nakaumi after the decline of seagrass beds. This affected the local economy, inducing not only eutrophication but also the collapse of local fisheries. On the other hand, at adjacent Lake Shinji, loss of submerged aquatic vegetation induced an increase of the commercial filter-feeding bivalve, Corbicula japonica, which doubled the fishery yield in the lake.  相似文献