Measurements Combination of Elastic Anisotropy and Anisotropy of Magnetic Susceptibility on Case Study in Igneous Rock of Lava Flow Type from Ijen Volcanic Complex, East Java

2nd Southeast Asian Conference on Geophysics

Ndari, N.R.D.W.^1 ; Bijaksana, S.^1 ; Nurhandoko, B.E.B.^2 ; Latief, F.D.E.^2

Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Ganesha 10, Bandung

40132, Indonesia^1

Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Ganesha 10, Bandung

40132, Indonesia^2

关键词: Anisotropy measurements;    Anisotropy of magnetic susceptibility;    Anisotropy parameters;    Cylindrical specimens;    Elastic anisotropy;    Microcomputed tomography;    Positive correlations;    Preferred orientations;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/318/1/012017/pdf
DOI  :  10.1088/1755-1315/318/1/012017

来源: IOP

【 摘 要 】

Research about the anisotropy parameters of rock is important for geophysical investigations. This research was a preliminary study which aims to find the relationship between elastic anisotropy and anisotropy of magnetic susceptibility in igneous rock of lava flow type with MR1 code and to interpret preferred orientation in MR1 sample based on the integration of anisotropy measurement results with the supported results from micro-computed tomography (μCT) analysis, petrography analysis and geological data analysis. This research has never been done before. This study was divided into several main stages consist of elastic anisotropy measurements on a cube-shaped specimen to determine the direction of maximum velocity and elastic anisotropy parameter values, anisotropy of magnetic susceptibility measurements on six cylindrical specimens to determine the direction of maximum susceptibility (magnetic mineral orientation) and AMS parameter values, petrography analysis on the all sides of the cube in order to observe preferred orientation in mineral and μCT analysis in a cylindrical specimen to determine the pore trend of rock. This study showed the relationship between AMS and elastic anisotropy in MR1 sample which indicated by positive correlation between the direction of maximum susceptibility and maximum velocity. Based on the results, MR1 sample has elastic anisotropy degree ranges from 2,6 % - 6,6 % for P waves and 2,2 % - 4 % for S waves and anisotropy of magnetic susceptibility degree around 2,6 % - 5,4 %. The integration of all measurement results including the direction of maximum velocity, direction of maximum susceptibility, preferred orientation in mineral, pore trend, and dip direction of sheeting joint indicate preferred orientation in MR1 sample towards NE-SW. One possible cause of such preferred orientation is the direction of the lava flow. Further studies in this topic are needed to support this hypothesis.