Origin of High Electrical Conductivity in the Lower Continental Crust: A Review

Effect of chemical composition on the electrical conductivity of gneiss at high temperatures and pressures

“…Aside from the chemical composition, other available alternative causes for high conductivity anomalies can be considered, such as water in nominally anhydrous minerals (Wang et al, 2006;Yang, 2011;Karato, 2009, 2014a), interconnected saline (or aqueous) fluids (Hashim et al, 2013;Shimojuku et al, 2014;Sinmyo and Keppler, 2017;Guo et al, 2015;Li et al, 2018), partial melting (Wei et al, 2001;Maumus et al, 2005;Gaillard et al, 2008;Ferri et al, 2013;Laumonier et al, 2015Laumonier et al, , 2017Ghosh and Karki, 2017), interconnected secondary high conductivity phases (e.g., FeS, Fe 3 O 4 ; Jones et al, 2005;Bagdassarov et al, 2009;Padilha et al, 2015), dehydration of hydrous minerals (Wang et al, 2012(Wang et al, , 2017Manthilake et al, 2015Manthilake et al, , 2016Hu et al, 2017;Sun et al, 2017a, b;Chen et al, 2018) and graphite films on mineral grain boundaries (Freund, 2003;Pous et al, 2004;Chen et al, 2017). In consideration of the similar formation conduction and geotectonic environments, the Himalaya-Tibetan orogenic system was compared with the Dabie-Sulu UHPM belt and explained high electrical conductivity anomalies.…”

Geophysical Properties of the Near Surface Earth: Electrical Properties

“…Minor sources of conduction in the upper crust are associated with the presence of highly conducting phases such as graphite Glover and Adám, 2008;Glover and Vine, 1992;Selway, 2014;Yang, 2011;Yoshino and Noritake, 2011) or sulfides (Duba et al, 1994;Einaudi et al, 2005;Glover and Vine, 1994), the latter of which rarely have sufficient connectedness to contribute significantly to the overall conductivity of the rock.…”

“…In a more academic sphere, the applications of the concepts described in this chapter are used for understanding the continental crust (e.g., Glover and Adám, 2008;Vine, 1992, 1995;Glover et al, 2000b;Yang, 2011) and oceanic crust (e.g., Baba, 2005;Gung et al, 2003;Key et al, 2013;Yoshino et al, 2008); the triggering of natural and synthetic earthquakes (e.g., Chelidze et al, 2003;Cyr et al, 2010); volcanic activity monitoring (e.g., ; the properties of lunar (e.g., Li et al, 2005), Martian (e.g., Carter et al, 2009), and asteroidal (e.g., Wittmann et al, 1999) materials; and soil science (e.g., Robinson et al, 2003;Peplinski et al, 1995). Counterintuitively, perhaps, some of the electrical conductivity models have been applied in fields as varied as catalysis research (e.g., Zhang and Catchmark, 2011) and food engineering (e.g., Jha et al, 2011;Jindal et al, 2013).…”

Structures and geometries of the Tajo Basin crust, Spain: Results of a magnetotelluric investigation compared to seismic and thermal models

“…As always when we sense a pervasive conductor in the lower crust, we can only be very speculative about its cause as we can never retrieve samples in in situ conditions. Candidates have been proposed by many authors over the last half century to explain the observed enhanced conductivity in the continental lower crust [e.g., Jones , ; Brown , ; Yang , ], and all are contentious and none without objection. The notion of interconnected graphitic thin films [e.g., Duba and Shankland , ; Frost et al , ], a candidate also much promoted for the lithospheric mantle, is discredited by the recent laboratory measurements of Yoshino and Noritake [].…”