Seismic structure and seismogenesis off Sanriku region, northeastern Japan   总被引：2，自引：0，他引：2  

Narumi Takahashi  Shuichi Kodaira  Tetsuro Tsuru  Jin-Oh Park  Yoshiyuki Kaneda  Kiyoshi Suyehiro  Hajimu Kinoshita  Shintaro Abe  Minoru Nishino  Ryota Hino 《Geophysical Journal International》2004,159(1):129-145

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吴丰波  张书毕  张秋昭  侯晓真 《大地测量与地球动力学》2013,33(5):140-144

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大厚度自重湿陷性黄土地基处理深度和剩余湿陷量问题的合理控制     

张世径  黄雪峰  朱彦鹏  杨校辉  姚志华 《岩土力学》2013,34(Z2):344-350

为研究大厚度自重湿陷性黄土地区地基处理深度与剩余湿陷量的合理控制关键技术难题,对采用不同处理深度的挤密地基进行了大面积深层浸水载荷试验。试验结果表明：对采用挤密地基处理在6～12 m深度以下进行深层浸水后均发生不同程度的地基湿陷下沉,而地基处理在15 m深度时（剩余湿陷量远大于200 mm）地基整体实际下沉量相对较小,说明现行的《湿陷性黄土地区建筑规范》对乙、丙类建筑地基关于最小处理深度的规定过于严格,不符合现有的经济技术水平,建议在采取一定措施的情况下将12~15 m作为乙、丙类建筑在大厚度自重湿陷性黄土地区地基处理的合理深度。并针对现行规范中对乙、丙类建筑剩余湿陷量控制的不合理之处,提出了“剩余湿陷量折减系数” 这个概念,并提出了该折减系数的建议值,可为同类工程建设和规范修订提供一定的参考。  相似文献   

Fourth‐ to third‐order cycles in the Hakobuchi Formation: Shallow‐marine Campanian final deposition of the Yezo Group,Nakagawa area,northern Hokkaido,Japan     

Hisao Ando  Yoshitaka Tamura  Daisuke Takamatsu 《Island Arc》2010,19(4):567-589

The Yezo Group has a wide longitudinal distribution across Hokkaido, northern Japan. It represents a Cretaceous (Early Aptian–Late Maastrichtian) and Late Paleocene forearc basin‐fill along the eastern margin of the paleo‐Asian continent. In the Nakagawa area of northern Hokkaido, the uppermost part of the Yezo Group consists of the Hakobuchi Formation. Along the western margin of the Yezo basin, 24 sedimentary facies (F) represent 6 facies associations (FA), suggesting prevailing storm‐dominated inner shelf to shoreface environments, subordinately associated with shoreface sand ridges, outer shelf, estuary and fluvial environments. The stacking patterns, thickness and facies trends of these associations allow the discrimination of six depositional sequences (DS). Inoceramids Sphenoceramus schmidti and Inoceramus balticus, and the ammonite Metaplacenticeras subtilistriatum, provide late Early to Late Campanian age constraints to this approximately 370‐m thick final stage of deposition and uplift of the Yezo forearc basin. Six shallow‐marine to subordinately non‐marine sandstone‐dominated depositional sequences include four 10 to 110‐m thick upward‐coarsening regressive successions (FS1), occasionally associated with thin, less than 10‐m thick, upward‐fining transgressive successions (FS2). The lower DS1–3, middle DS4–5 and upper DS6 represent three depositional sequential sets (DSS1–3). These eastward prograding and westward retrograding recurring shallow‐marine depositional systems may reflect third‐ and fourth‐order relative sealevel changes, in terms of sequence stratigraphy.  相似文献   

Tectonics of an Early Carboniferous forearc inferred from a high-P/T schist-bearing conglomerate in the Nedamo Terrane, Northeast Japan     

Takayuki  Uchino  Makoto  Kawamura 《Island Arc》2010,19(1):177-191

The Nedamo Terrane, an Early Carboniferous accretionary complex, is the oldest biostratigraphically dated accretionary complex in Japan. The purpose of this study is to describe and interpret a conglomerate from the Nedamo Terrane that contains clasts of high-pressure/low-temperature (high- P/T ) schist (mainly garnet-bearing phengite schist) and ultramafic rock, and to infer the tectonics of an Early Carboniferous arc–trench system at the eastern margin of the paleo-Asian continent. Clasts of high- P/T schist and ultramafic rock within the conglomerate make up 8.4 and 6.7% of the total clasts, respectively, based on modal counts. These clasts are subangular to subrounded, whereas volcanic clasts are well rounded. The source of the schist clasts, which yield a radiometric age of 347–317 Ma, is considered to be the Renge Metamorphic Rocks of Southwest Japan or equivalent rocks. Based on the chemical composition of chromian spinel, the source of ultramafic clasts is inferred to be the island-arc-type Ordovician Miyamori and Hayachine ultramafic complexes in the Kitakami Massif. The conglomerate records multiple provenance regions, including an island arc (South Kitakami Terrane) and a forearc ridge; the high P/T schist and ultramafic rocks were exhumed in the forearc region. The duration of the interval from the early stages of exhumation of the schist to its deposition in the trench as clasts is estimated to have been less than 30 my.  相似文献   

西藏洞错埃达克质火山岩LA-ICP-MS锆石U-Pb年龄及其构造意义   总被引：1，自引：1，他引：0  

闫国川  王保弟  刘函  王立全  周放 《地质通报》2017,36(10):1772-1782

班公湖-怒江缝合带是青藏高原的主要缝合带之一,其闭合时限还存在争议,制约了班公湖-怒江特提斯洋演化历史的研究。在班公湖-怒江缝合带洞错地区新识别出一套早白垩世晚期的粗安岩,LA-ICP-MS测得其锆石~(206)Pb/~(238)U年龄为102.0±1.9Ma,岩石高SiO_2、Al_2O_3、富Na及高的Sr/Y值(25.2~42.2),贫Nb(11.1×10~(-6)~16.6×10~(-6))、Y(11.7×10~(-6)~18.3×10~(-6))和Yb(1.06×10~(-6)~1.77×10~(-6)),轻、重稀土元素分异明显,具有与埃达克质岩相似的地球化学特征,同时具有高Mg~#的特点(Mg~#=50.0~54.1)。认为洞错高Mg~#埃达克质岩很可能是残留洋壳部分熔融上升过程中交代地幔的产物,形成于板内构造环境。由此推测,洞错早白垩世晚期埃达克质岩的形成与班公湖-怒江洋盆闭合后拉萨地块与羌塘地块碰撞有关,结合区域地质资料,认为班公湖-怒江特提斯洋闭合时限应该在102Ma之前。  相似文献   

琼东南盆地北礁凹陷梅山组顶部丘形反射特征及成因分析   总被引：4，自引：3，他引：1  

李俞锋  蒲仁海  屈红军  李斌 《海洋学报》2017,39(5):89-102

南海琼东南盆地北礁凹陷中中新统梅山组顶部丘形反射目前引起广泛关注,前人推测为生物礁、重力蠕动与底流叠加成因、等深积丘等。本文通过钻井资料、二维、三维地震资料精细刻画丘形反射（残丘）和丘间水道特征及其成因。残丘及水道在北礁凸起不发育,在边缘斜坡中部和高地较发育,且有向高地两边规模减小趋势,不具对称性,残丘和水道呈平行-亚平行近E-W向展布,局部有合并分叉现象,与北礁凸起走向呈一小角度;丘宽562~1 223 m,丘高29~87 m,丘长10 km左右,存在丘翼削蚀,水道底蚀现象。地震属性分析表明三维工区西南部残丘间水道由砂泥岩互层充填,形成长条形强振幅,而残丘为中-低振幅;地震、钻井资料分析表明丘形反射（残丘）由钙质泥岩和泥岩组成,属于半深海沉积,且残丘内部波阻抗为5.0×106~6.5×106kg/m3·m/s,低于火山岩、灰岩波阻抗,属于砂泥岩地层范畴;根据梅山组下段水道由西向东强振幅变弱、分叉、前积反射和海山附近底流（等深流）沉积剥蚀特征综合判定底流古流向自西向东,根据海山两翼地震反射特征推测底流可追溯至晚中新世早期（11.6 Ma BP）,综合分析认为,研究区中中新统梅山组丘形反射是晚中新世早期底流切割梅山组地层形成的残丘。  相似文献   

Experiment on Collisionless Plasma Interaction with Applications to Supernova Remnant Physics     

C. Courtois  R. A. D. Grundy  A. D. Ash  D. M. Chambers  R. O. Dendy  K. G. Mcclements  N. C. Woolsey 《Astrophysics and Space Science》2005,298(1-2):93-98

Results from a scaled, collision-free, laser-plasma experiment designed to address aspects of collisionless plasma interaction in a high-plasma β supernova remnant (SNR) are discussed. Ideal magneto-hydrodynamic scaling indicates that the experimental plasma matches the SNR plasma at 500 ps. Experimental data show that the magnetic field can alter the plasma density profile when two similar plasmas interact in a colliding geometry. These results are not explained by magnetic-field pressure; they do, however, suggest magnetic field penetration that localizes the plasma particles to the Larmor radius, which appears smaller than the size of the experiment and the particle mean-free paths and may thus increase the effective collisionality of the interacting plasma system.  相似文献   

脉冲星与超新星遗迹成协的候选体     

田文武  LEAHY Denis 《天文学进展》2004,22(4):308-317

从所有已被提出和发现的230多颗超新星遗迹和1300多颗脉冲星中，总结出一个共50对脉冲星与超新星遗迹成协候选体的样本．其中至少20对因为环绕脉冲星的脉冲星风云已被探测到，其成协性应该是真实的。结合近来的观测结果，对导致这种成协对缺失现象的各种因素进行了讨论，尤其深入地讨论了这个样本中有代表性的3个很可能成协的脉冲星与超新星遗迹对。  相似文献   

RELATION BETWEEN WATER TEMPERATURE, WATER EXCHANGE AMOUNT, FEED AND PRAWN DISEASE   总被引：1，自引：0，他引：1  

臧维玲  戴习林  江敏  张建达  黄建华  孙绍永  徐桂荣  李士华 《中国海洋湖沼学报》1997,15(3):212-215

ImooUrnONTheedycarsePiddricofprawndiscaseintheprawnculturecoastalarmsofChi-naandsoutheastAsiaresultedinnoproduCtinnoutputfromrnostprawnpondsandheaVyerenoAnclosscyumbull,l994).Upt0now,devemeasimtopreventandtreatthediseasehavenotbopresental,althoughwaterenvironmentdeteriorationisconunn-lyknowntobethekcyfactorcausingthisdhase(Jiang,l994).ThispreliIninrystudyonthereati0nsbetweenprawndiseaseandfactorsthatseriouslyaffodwatetenvirDimtalquality(WaterteInPeratllre,waterexchangeamount,andarnountSa…  相似文献