TY - THES

T1 - Applicability of Geophysical methods for the prospection of Paleo-laterite deposits

AU - Reke, Tereze

N1 - no embargo

PY - 2023

Y1 - 2023

N2 - Already in the 19th and 20th centuries, laterite ore was mined at the Kraubath massif – an ophiolitic complex in the Easter Alps, Austria. There the laterite ore bodies are incorporated between layers of Neogene clastic sediments. However, due to the costly transporting and the unsatisfactory quality of the ore, the excavation of the laterite ore deposits was ceased. Now once again it is being investigated for its possible economic utilization. The spatial distribution and dimensions of laterite ore can be resolved with the use of different geophysical methods. However, the applicability of geophysical methods in the lateritic environment has been tested in only a few published cases and with few geophysical methods. In this thesis, the laterite ore bodies were studied by applying four geophysical methods – electrical resistivity tomography, magnetics, self-potential, and electromagnetics – for the evaluation of each of the methods feasibility for delineating discrete anomalies related to the laterite ore. The data for the analysis was acquired during the master’s course “Geophysical and Geochemical Field Project,” organized from 2016 to 2021. Subsequently, it was processed for further interpretation and representation. The gained end results were achieved by an individually adjusted flow for each applied geophysical method and location. The obtained results assess the suitability of each applied geophysical method. ERT results displayed low resistivity zones which were interpreted as laterite based on direct data from the field and borehole. Few uncertain low resistivity zones, where clear indications of laterite existence were not found, were supplemented by magnetic data which helped to determine laterite ore body location. Magnetic data 3-D models, constrained by susceptibility values measured in the field, were constructed for the investigation areas, covering areas where ERT methods profiles did not reach. Self-potential and electromagnetic methods contributed more like additional methods for conforming ERT and magnetics results by providing approximate locations of the ore bodies.

AB - Already in the 19th and 20th centuries, laterite ore was mined at the Kraubath massif – an ophiolitic complex in the Easter Alps, Austria. There the laterite ore bodies are incorporated between layers of Neogene clastic sediments. However, due to the costly transporting and the unsatisfactory quality of the ore, the excavation of the laterite ore deposits was ceased. Now once again it is being investigated for its possible economic utilization. The spatial distribution and dimensions of laterite ore can be resolved with the use of different geophysical methods. However, the applicability of geophysical methods in the lateritic environment has been tested in only a few published cases and with few geophysical methods. In this thesis, the laterite ore bodies were studied by applying four geophysical methods – electrical resistivity tomography, magnetics, self-potential, and electromagnetics – for the evaluation of each of the methods feasibility for delineating discrete anomalies related to the laterite ore. The data for the analysis was acquired during the master’s course “Geophysical and Geochemical Field Project,” organized from 2016 to 2021. Subsequently, it was processed for further interpretation and representation. The gained end results were achieved by an individually adjusted flow for each applied geophysical method and location. The obtained results assess the suitability of each applied geophysical method. ERT results displayed low resistivity zones which were interpreted as laterite based on direct data from the field and borehole. Few uncertain low resistivity zones, where clear indications of laterite existence were not found, were supplemented by magnetic data which helped to determine laterite ore body location. Magnetic data 3-D models, constrained by susceptibility values measured in the field, were constructed for the investigation areas, covering areas where ERT methods profiles did not reach. Self-potential and electromagnetic methods contributed more like additional methods for conforming ERT and magnetics results by providing approximate locations of the ore bodies.

KW - Laterite deposits

KW - electrical resistivity tomography

KW - magnetism

KW - electromagnetic method

KW - self-potential

KW - geophysics

KW - Laterit-Vorkommen

KW - Elektrische Widerstandstomographie

KW - Magnetik

KW - Elektromagnetische Induktion

KW - Eigenpotential

KW - Geophysikalische Prospektion

U2 - 10.34901/mul.pub.2024.024

DO - 10.34901/mul.pub.2024.024

M3 - Master's Thesis

ER -