Figure 3
Unconstrained inversion result for susceptibilities; black line shows the location where the NRM value changes according to the lithology (D); see text for details. (Top) Observed and modeled ground magnetic data along profile 13 (see Fig. 2C for location). (A) Block model with vertical fault contact. (B) Block model shaped according to the dip of the fault. (C) Slab model shaped according to the dip of the fault. (D) Lithology sketch of the fault zone (C).
Contexts in source publication
Context 1
... Observed and modeled ground-magnetic data along model line 13 (see Fig. 2C for location). Results of susceptibility inversion using different starting values (k 0 ) in SI units for the slabs (see Fig. 3D ...
Context 2
... models in Fig. 3A, 3B display rectangular blocks in the profile plane. Because the potential field resolution capability decreases with depth, these models consist of blocks of different size with the smallest blocks near to the surface. The start model in Fig. 3A was populated with the vector mean NRM properties (Table 1) The slab model describes the ...
Context 3
... models in Fig. 3A, 3B display rectangular blocks in the profile plane. Because the potential field resolution capability decreases with depth, these models consist of blocks of different size with the smallest blocks near to the surface. The start model in Fig. 3A was populated with the vector mean NRM properties (Table 1) The slab model describes the magnetization in fault zones by a series of parallel slabs, each with constant magnetic attributes and having the same strike and dip as the fault (Fig. 3C). All slabs are terminated at the same depth. This simple model structure honors the strike ...
Context 4
... consist of blocks of different size with the smallest blocks near to the surface. The start model in Fig. 3A was populated with the vector mean NRM properties (Table 1) The slab model describes the magnetization in fault zones by a series of parallel slabs, each with constant magnetic attributes and having the same strike and dip as the fault (Fig. 3C). All slabs are terminated at the same depth. This simple model structure honors the strike and dip of the fault zone but does not allow for changes in magnetization with increasing depth. This assumes that magnetization changes occur in parallel with the fault plane with the same degree of ...
Context 5
... inversion, the slabs were assigned average site NRM properties and susceptibility was set to zero. The inversion result (Fig. 3C) shows that the highest susceptibilities are near to the fault plane, and only a few slabs have negative susceptibilities that would require correction. Table 2 summarizes the advantages and disadvantages of the block versus the slab modeling ...
Similar publications
The existence of pieces of the Variscan belt in the Alpine basement has been acknowledged for a long time but the correlation of these massifs to the litho-tectonic domains established in Western Europa outside the Alpine chain is still disputed. Due to their ubiquitous character, the abundant late Variscan migmatites and granites are useless to re...
Flux materials are indispensable in iron ore refining process to effectively segregate gangue minerals and to improve other physicochemical properties. Lately, the demand for metallurgical grade flux materials such as limestone and dolomite for iron and steel manufacturing industries in India has surged manifold and depends largely on imports due t...
Citations
... This information is critical to the study of the past history of the Earth's magnetic field and is also a key tool to interpret magnetic anomalies on Earth and other rocky planetary bodies. The mineral sources and nature of remanent magnetization reflected in crustal magnetic anomalies are ongoing topics of research (Brown & McEnroe, 2008;Clark, 1999;Ferré et al., 2021;McEnroe et al., 2002McEnroe et al., , 2018McEnroe, Fabian, et al., 2009;Michels et al., 2018Michels et al., , 2020Purucker & Whaler, 2007;ter Maat et al., 2019ter Maat et al., , 2020. ...
Distinct crustal remanent magnetic anomalies are a strong indicator of rocks with stable natural remanent magnetization (NRM) carriers. The latter are able to store information on the history of a rock over long geological periods, and can therefore be used for a variety of applications in the field of paleomagnetism and rock magnetism. Typically, paleomagnetic and rock-magnetic studies rely on rocks bulk magnetic properties. With the advent of high-resolution magnetometric scanning techniques, it is now possible to map magnetic sources at the mineral scale, identify the different magnetic carriers, and analyze the effect of geometry, microstructures, and composition on their magnetic response. We investigate the stability of discrete remanent magnetization sources of a microcline–sillimanite gneiss sample from Russell Belt with a strong NRM, by scanning the sample before, and after alternating field demagnetization to 100 mT. We quantified changes in the magnetization intensity and direction by inverting the magnetic scan data. Here, we confirm that the exsolved titanohematite with ilmenite lamellae is the major source of magnetization, and the coexisting multidomain hematite grains contribute little to the NRM, or the magnetic anomalies. The microstructures in the titanohematite control local magnetic properties at the mineral scale. Magnetic modeling results suggest a consistent average magnetization direction before and after demagnetization at both the grain and thin section scale, with a decrease in the magnetization intensity of ≈30%. Results are consistent with previous bulk magnetic measurements and the likelihood to use high-resolution magnetometric techniques in future magnetic studies is high.
