权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Collisional and collapse processes of reef-seamount complex

礁-海山复合体的碰撞和塌陷过程

基本信息

批准号：
04640707
负责人：
SANO Hiroyoshi
金额：
$ 1.41万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1993
项目状态：
已结题

项目摘要

We identified the prevailing internal textural destruction in the Tsukumi Limestone through the field and microscopic examinations. Our research revealed that the collisional and accretion of the Carboniferous-Permian Tsukumi Limestone in the Chichibu terrane is most satisfactorily explained by the working hypothesis by Sano and Kanmera(1991). The sequence of the collisional and accretionary events of the Tsukumi Limestone is summarized as follows ; encroachment of the Tsukumi oceanic buildup resting on a seamount into a trench area, split of the buildup by normal faults along the outer trenchslope and generation of fault-induced fractures, large scale collapse of the buildup along with its pedestal and internal textural destruction of the collapse blocks, trenchward-movement of a wedge of the collapse products and their intermixing with the wedge, displacement of the collapse products and their mixing with trench-fill sediments and offscraping accretion of the collisional products fogether with the trench-fill sediments and their incorporation into an accretionary prism. All these events took place in early Early to early Middle Jurassic time. Worthy to note is that the basaltic pedestal of the buildup was also involved into the collisional collapse events.Addition to the Tsukumi Limestone, the late Paleozoic limestones in the Akiyoshi terrane were examined. Though the further examination is needed, internal textural destruction is also widespread in these limestones. The results imply that their accretion can be explained by the collisional collapse model avobe described.The whole of our results mean that the working hypothesis proposed by Sano and Kanmera(1991) is applicable to another accreted oceanic limestones and is ot great significance in the accretion tectonics.

我们通过野外和显微镜检查确定了筑美石灰岩中普遍存在的内部结构破坏。我们的研究表明，佐野和堪梅拉（1991）的工作假说最满意地解释了秩父河石炭纪-二叠纪筑美石灰岩的碰撞和增生。筑美灰岩的碰撞和加积事件序列总结如下：位于海山上的筑美海洋堆积物侵入海沟区，正断层沿着外海沟斜坡分裂堆积物并产生断层诱导裂缝，堆积物沿着其基座大规模坍塌，坍塌块体内部结构破坏，崩塌产物楔体的向沟运动及其与楔体的相互混合、崩塌产物的位移及其与沟填沉积物的混合、碰撞产物与沟填沉积物的刮积及其与加积棱柱体的结合。这些事件都发生在早侏罗世早期至中侏罗世早期。值得注意的是，玄武岩基座的建设也参与了碰撞崩溃事件。除了筑美石灰岩，晚古生代石灰岩在秋吉县进行了检查。虽然需要进一步的检查，内部结构破坏也普遍存在于这些石灰岩。这些结果表明，它们的增生作用可以用一个不可描述的碰撞坍塌模型来解释，说明佐野和坎梅拉（1991）提出的工作假说也适用于另一种增生的大洋灰岩，在增生构造学上没有重要意义。