Fracture System Developed in the Takinoue Geothermal Area
Fracture System Developed in the Takinoue Geothermal Area
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泷上地热区开发的裂缝系统
DOI：
10.11367/grsj1979.15.109
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
N. Doi
中科院分区：
文献类型：
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作者：
S. Koshiya;Kazuyoshi Okami;Yasushl Kikuchi;T. Hirayama;Y. Hayasaka;M. Uzawa;K. Honma;N. Doi
对日本本州东北部岩手县竹上地热区的地质和裂缝进行了研究，从构造地质学的角度阐明了裂缝的发育过程和应力场。在此基础上，讨论了裂缝系统与地热水路径的关系。结论如下：(1)认为Torigoenotaki英安岩和Matsuzawa英安岩岩体是南岛泽组的熔岩和侵入段。(2)将南川组凝灰岩段重新定义为北川组。(3)根据热液脉和多数小断裂的优势取向，将其划分为NNW-SSE ~ NW-SE走向中倾系统（nw -中倾系统）、NW-SE走向陡倾系统（nw -陡倾系统）、NE- sw ~ E-W走向陡倾系统（NE ~ E-W系统）和水平系统4个系统。(4) NE - E-W体系由侧向位移和正向位移的脉断层组成，均由水平NW-SE最小主应力轴（F3）的应力场形成。(5)北西—中倾体系和北西—陡倾体系由侧向位移至正向位移的脉和断裂组成，均是由北北—南南—南南—南南最小轴水平应力场（F2）形成的。(6)本研究裂缝分析得到的最古老应力场为最小轴为水平NNESSW - NE-SW （F1）的张性应力场，存在于中新世Yamatsuda组倾斜之前。此后，F2应力场至少在较年轻的火山产物（大松仓火山产物）沉积后继续存在。最新的应力场为F3，至少在研究区0.2Ma之后持续至今。(7)目前的地热水运移路径受北东—东西向断裂控制。
Geology and fractures in the Takinoue geothermal area, Iwate Prefecture, Northeast Honshu, Japan are investigated to clarify the process of development of fractures and the associated stress field from the structural geological point of view. From the above, the relationship between fracture systems and paths of geothermal water is discussed. The conclusions are as follows: (1) The Torigoenotaki Dacite as well as the Matsuzawa dacitic rock body is regarded as the lava and intrusive member of the Minamishirasawa Formation. (2) The tuffaceous member of the Minamishirasawa Formation is newly defined as the Kitashirasawa Formation. (3) The hydrothermal veins and most minor faults are classified into four systems on the basis of their dominant orientations, that is, NNW-SSE to NW-SE strike and moderate dip system (NW-moderate dip system), NW-SE strike and steep dip system (NW-steep dip system), NE-SW to E-W strike and steep dip system (NE to E-W system) and horizontal system. (4) The NE to E-W system consists of veins and faults with lateral and normal displacement, both of which were formed by the stress field with horizontal NW-SE minimum principal stress axis (F3).(5) The NW-moderate dip system and NW-steep dip system consist of veins and faults with lateral to normal displacement, both of which were formed by the stress field with horizontal NNE-SSW to ENE-WSW minimum axis (F2). (6) The oldest stress field obtained from the fracture analysis in this study is the tensional stress field with horizontal NNESSW to NE-SW minimum axis (F1), which existed before the tilting of the Miocene Yamatsuda Formation. Thereafter, the F2 stress field continued at least after the deposition of the younger volcanic products (the Omatsukura volcanic products). The latest stress field is F3, which continues at least after 0.2Ma in the studied area to the present. (7) The present paths of geothermal water are controlled by the fractures belonging to the NE to E-W system.