Flow Phenomena within the Jurassic Accretionary Complexes of Northeast Japan.

研究目的是揭示中生代增生杂岩中的泥质注入、砂槛-岩墙、流体化构造等与流体有关的流动现象（大岛岩带、伊栋那普岩带和北方北上岩带），并解释了增生杂岩中孔隙流体行为的意义。在Cape Shiragami地区观察到小规模的由于泥浆注入而形成的含砾泥岩体。侵入并注入浊积蚀变岩和绿色岩中。泥浆注入的几何形状一般为细脉（-膜），有时呈分支状，但在一个实例中呈不规则的浸渍网络状。碎屑岩蚀变的容矿岩石在注入前有明显的构造变形。夹杂物中偶尔会出现拼图结构。这种侵入/注入是由低固结泥质沉积物在高围压和过量孔隙流动下的流化作用引起的 ...更多信息 在增生杂岩较深部位的滑脱/逆冲带中，相对固结的容矿岩石内部压力较小。砂岩床-岩墙：在大岛带Orito-hama海岸的浊流蚀变中识别出粗粒砂岩岩床/岩墙，可分为岩墙岩床过渡型、多分支型、捏隆细脉群型和厚面型。在这种类型中，偶尔会观察到类似于岩床中豆荚状“储层”的特殊结构，其中“注入”了几条细支脉。结果表明，当砂体孔隙压力超过围岩强度时，由于水力劈裂作用，高孔隙压力的“流化砂”像注射器一样被推入半固结的围岩中，并呈脉状喷入，上述流化-喷入现象揭示了在加积杂岩中广泛发生的湿沉积物的流动（-侵入）过程。孔隙流体行为与增生杂岩混合相的形成机制密切相关。少

The intention of this study is to exhibit the fluid-involving flow phenomena, such as mud-injection, sand sill - dyke, fluidized structure noted in the Mesozoic accretionary complexes (the Oshima Belt, Idon'nappu Belt and the Northern Kitakami Belt) of Northeast Japan, and to interpret the significance of the pore-fluid behavior in accretionary complex.Mud Injection : Pebbly mudstone bodies as a result of mud injection is observed in the Cape Shiragami Area on a small scale. It intrudes and injected into the turbiditic alternation and green rocks. Geometry of the mud injection is generally thin veinlet (-film) sometimes branched, but shows irregularly impregnating network-form in a case. Host rocks of clastic alternation were tectonically deformed clearly before the injection. Jigsaw-puzzle structure is occasionally recognized in the inclusion. Such intrusion/injection were caused by the fluidization of underconsolidated muddy sediments under high confining pressure and excess pore-flu … More id pressure within relatively consolidated host rocks in the decollement/thrust zone of comparatively deep part of accretionary complex.Sand Sill - dyke : Sills/dykes of coarse-grained sandstone are recognized in the turbiditic alternation in the Orito-hama coast, Oshima Belt.They are classified as follows : dykesill transitional type, multi-branching type, pinch-and-swell veinlet swarm type and thick planar type. Peculiar structure as pod-like "reservoir" in a sill, which "injects" several thin branched veins, is occasionally observed in this type. It is concluded that the "fluidized sand" with high pore-pressure was pushed into the semi-consolidated host rock like syringe, and injected as branched veins in consequence of hydraulic fracturing induced when the pore-pressure of the sand exceeded the strength of wall-rock.Fluidization - injection phenomena described above reveal that the flow (-intrusion) process of wet-sediment take place extensively in accretionary complex. And it suggests that the behavior of pore-fluid is deeply concerned with the formative mechanism of the mixed facies characteristic of accretionary complex. Less