Anwendung der Induzierten Polarisation in der Graphitexploration

Abstract

ZusammenfassungDiese Studie präsentiert die Anwendung der Induzierten Polarisation (IP) für die Charakterisierung einer Graphitlagerstätte. Basierend auf Labormessungen zeigen wir die Sensitivität von IP-Messungen hinsichtlich Veränderungen der Korngröße und der spezifischen Oberfläche von Graphit in Gesteinsproben und auf der Feldskala. Des Weiteren demonstrieren wir, dass IP-Feldmessungen eine klarere Abgrenzung von graphitreichen Untergrundbereichen ermöglichen als die alleinige Bestimmung der elektrischen Leitfähigkeit.

Combining geophysical prospection and core drilling: Reconstruction of a Late Bronze Age copper mine at Prigglitz‐Gasteil in the Eastern Alps (Austria)

“…The thickness of the dump increased continuously from west to east, reaching a constant thickness of $10 m at E36. For the most part, the dump was characterized by high resistivity and medium phase values, as expected for materials containing low (but measurable) volumetric contents of iron sulphides and metallic minerals (Bücker et al, 2018(Bücker et al, , 2019Flores-Orozco et al, 2021). A low resistivity anomaly between E56 and E61 corresponded to anthropogenic noise, including the modern roadway between the farmhouse at Gasteil No.…”

“…However, siderite does not usually produce a measurable polarization effect at the frequencies under investigation (Abdel Aal et al, 2014 ). The high polarization response is therefore more likely to indicate concentrations of copper ore, which commonly increases the polarization response (e.g., Flores‐Orozco et al, 2021 ) or magnetite, another iron oxide that also enhances polarization (Hubbard et al, 2014 ). Another area with elevated polarization values was located between E16 and E28 at a depth of about 7–17 m, that is, exactly in the border zone between the limestones and the metaquartz wackes.…”

“…Both electrical resistivity and induced polarization imaging techniques are based on the injection of current into the ground by means of a pair of electrodes and measuring the resulting voltage across another electrode pair (see Binley & Slater, 2020 ; Flores Orozco et al, 2018 , 2020 , 2021 ). Imaging measurements comprised hundreds of four‐electrode measurements by the combination of dozens of electrodes, to map for lateral and vertical changes in the electrical properties of the subsurface (Flores Orozco et al, 2018 , and references therein).…”

“…For instance, geomagnetic and georadar surveys have successfully delineated the full extent, number and depth of Neolithic flint‐mining shafts at Arnhofen in southern Germany (Faßbinder, 2003 ; Leopold & Völkel, 2003 , 2004 ). Electrical resistivity tomography, sensitive to the electronic conduction of metallic minerals (e.g., Bücker et al, 2018 ; Flores Orozco et al, 2015 ; Flores‐Orozco et al, 2021 ), was successfully applied in the prospection of the Alpine Bronze Age mining sites on the Mitterberg in the Austrian province of Salzburg, where the results permitted the interpretation of the superficially visible collapsed shafts (German Furchenpingen ) of the Main Lode and the Brandergang Lode (Herd, 2006 ; Herd & Taube, 2011 ; Stöllner, Breitenlechner, et al, 2011 , p. 124; Stöllner et al, 2006 , pp. 123–124; see also Thomas, 2018 , pp.…”