Acoustic properties of deformed rocks at the Nobeoka Megathrust in the Shimanto Belt, Kyushu, Southwest Japan.
Acoustic properties of deformed rocks at the Nobeoka Megathrust in the Shimanto Belt, Kyushu, Southwest Japan.
复制标题
日本西南部九州四万十带延冈巨型逆冲断层变形岩石的声学特性。
作者：
Hashimoto;Y.;Abe;S.;Tano;H.;Hamahashi;M.;Saito;S.;Kimura;G.;Yamaguchi;A.;Fukuchi;R.;Kameda;J.;Hamada;Y.;Kitamura;Y.;Fujimoto;K.;Hina;S.;Eida;M.
在受控有效压力（5-65 MPa，间隔5 MPa）和潮湿条件下，对来自野冈推力钻探项目（NOBELL）的岩心样品进行了纵波和横波速度（分别为Vp和Vs）和孔隙度的实验室测量。根据变形结构将样品分类为千枚岩、叶理碎裂岩或非叶理碎裂岩。千枚岩的Vp、Vs和孔隙度的实测值分别为5.17-5.57 km/s、2.60-2.71 km/s和2.75- 3.10%，片理碎裂岩的Vp、Vs和孔隙度的实测值分别为4.89-5.23 km/s、2.46-2.57 km/s和3.58- 4.53%;无叶理碎裂岩分别为4.90-5.32 km/s、2.51-2.63 km/s和3.79- 4.60%，这与先前在干燥条件下用露头样品进行的实验室实验结果一致。然而，我们的研究结果也表明，与以前采用钢丝绳测井方法的研究相比，Vp和Vs更高，孔隙度更低。Vp、Vs和孔隙度的变化受变形构造控制，千枚岩和片理化碎裂岩的变化大于非片理化碎裂岩。
Laboratory measurements for compressional and shear wave velocities (Vp and Vs, respectively) and porosity were conducted with core samples from the Nobeoka Thrust Drilling Project (NOBELL) under controlled effective pressure (5–65 MPa at 5 MPa intervals) and wet conditions. Samples were classified according to deformation texture as phyllite, foliated cataclasite, or non‐foliated cataclasite. Measured values of Vp, Vs, and porosity are within a range of 5.17–5.57 km/s, 2.60–2.71 km/s, and 2.75–3.10 %, respectively, for phyllite; 4.89–5.23 km/s, 2.46–2.57 km/s, and 3.58–4.53 %, respectively, for foliated cataclasite; and 4.90–5.32 km/s, 2.51–2.63 km/s, and 3.79–4.60 %, respectively, for non‐foliated cataclasite, which are all consistent with the previous laboratory experiments conducted with outcrop samples under dry conditions. However, our results also indicate higher Vp and Vs and lower porosity than those measured by the previous studies that adopted the wire‐line logging methods. The variations in Vp, Vs, and porosity are controlled by deformation structure and are greater for phyllite and foliated cataclasite than for non‐foliated cataclasite.