IDENTIFICATION IGNEOUS ROCK BASED on 2D and 3D RESISTIVITY ANALYSIS of GEOELECTRIC DATA
Fauzi Daffa Hanatha, Y Yatini*) and Suharwanto

*Geophysical Engineering, Universitas Pembangunan Nasional Veteran Yogyakarta, Jalan SWK 104 Condongcatur Yogyakarta

Abstract

The earth^s subsurface can be composed of many rocks, such as igneous rock, sedimentary rock, and metamorphic rock. Determination of rock types at the subsurface is carried out using geophysical methods. This study aims to identify igneous rock using a geoelectric method with a dipole-dipole configuration that utilizes subsurface resistivity values based on analysis of 2D and 3D resistivity cross-sections. The processing uses RES2DINV to get a 2D cross-section and Voxler to get a 3D cross-section. The resistivity value can be divided into four groups, namely very low with values < 100 &#937-m can be interpreted as claystone, low resistivity with values 100 &#937-m - 1000 &#937-m as loose material or sandstone, medium resistivity with values of 1000 &#937-m - 3000 &#937-m as deposits from weathered igneous rocks, and high resistivity with values > 3000 &#937-m as fresh igneous rocks. The distribution of igneous rocks is spread over the western to the southern part of the study area, which is an intrusion based on a 3D cross-section.

Keywords: Geoelectric, Dipole-Dipole Configuration, Resistivity, 2D Cross Section, 3D Cross Section.

Topic: Engineering