陸域断層の内部構造  [in Japanese] Architecture of onshore fault zones  [in Japanese]

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Abstract

<p>断層の内部構造に関し,この25年間における主として日本地質学会員の成果を中心にまとめた.脆性断層の研究において,野島断層掘削をきっかけに内部構造のみならず,断層の水理学的性質や摩擦の研究がさかんに行われ,断層研究における大きな転機となった.より深い脆性領域の断層岩内では圧力溶解クリープと,雲母類の塑性変形が報告され,そのダメージは結晶内歪を周囲の岩石に与えることなどが明らかになった.また脆性–塑性遷移領域に対しては応力や歪速度の条件を地質学的の評価しようとする試みが行われ,破壊開始過程や変形の空間的不均質が明らかにされている.さらに下部地殻では斜長石や輝石の転位クリープの一方で,変形中の細粒物質の生成による変形機構遷移の重要性が指摘されている.近年,下部地殻における破壊現象の痕跡が見つかっており,地震による応力集中が一つの可能性として考えられている.その理解には今後の研究が期待される.</p>

<p>We review research on the architecture of onshore fault zones. Drilling the Nojima Fault was a turning point in studies of shallow brittle faults, stimulating research on their hydrological and frictional properties. Investigations of the deep seismogenic zone of faults such as the Median Tectonic Line (MTL) have identified deformation mechanisms such as pressure solution, creep, and crystal plasticity of mica in foliated cataclasite. Cataclastic damage causes increased intracrystalline strain in surrounding rocks. Several studies of the Asuke shear zone and the MTL have estimated the stress and strain rate in the brittle–plastic transition zone. Some studies of the Hatagawa fault zone have revealed the processes involved in fracture nucleation and documented heterogeneous deformation on the scale of tens of kilometers. In the lower crust of the Hidaka metamorphic belt, evidence was found for plastic deformation of plagioclase and pyroxene by dislocation creep. It was also found that formation of fine-grained aggregates during deformation results in weakening by a change in deformation mechanism from dislocation creep to grain boundary sliding. Recently, evidence of fracturing has been found in deformed lower crustal rocks, possibly resulting from stress concentration at the down-dip termination of earthquake ruptures, although further studies are needed to confirm this inference.</p>

Journal

  • The Journal of the Geological Society of Japan

    The Journal of the Geological Society of Japan 124(9), 759-775, 2018

    The Geological Society of Japan

Codes

  • NII Article ID (NAID)
    130007530983
  • NII NACSIS-CAT ID (NCID)
    AN00141768
  • Text Lang
    JPN
  • ISSN
    0016-7630
  • NDL Article ID
    029311548
  • NDL Call No.
    Z15-174
  • Data Source
    NDL  J-STAGE 
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