Evolution of zircon deformation mechanisms in a shear zone (Lanzo massif, Western-Alps)

Finite lattice distortion patterns in plastically deformed zircon grains

“…Furthermore, deformed grains may be selectively destroyed during sample crushing and sieving. However, in the last years, a growing number of works have appeared that also study crystal-plastically deformed zircons in situ (e.g., Kaczmarek et al, 2011;McDonald et al, 2013;Piazolo et al, 2012;Timms et al, 2011). Following this trend, the current work presents new microstructural data from crystalplastically deformed zircon grains from common lithologies, where zircon grain sizes range from 10 to 50 µm in length.…”

“…Some of those zircons were derived from uncommon occurrences: (1) an impact basin (Moser et al, 2009(Moser et al, , 2011; (2) zircon-rich veins veins within a metaanorthositic body (Piazolo et al, 2012); (3) olivine gabbro derived from the ocean ridge (Reddy et al, , 2007or (4) xenolith from kimberlitic pipe . Other studies were focused on more widespread rock types and smaller zircons grains, less than 100 µm in length (Flowers et al, 2010;Kaczmarek et al, 2011;MacDonald et al, 2013;Reddy and Timms 2010;Schwarzt et al, 2010;Timms et al, 2012b). In addition, some of the studies examined embedded zircon grains that were extracted from the sample by means of heavy mineral separation (e.g., Kaczmarek et al, 2011;Moser at al., 2011;Reddy et al, 2009;Schwartz et al, 2010;.…”

“…Other studies were focused on more widespread rock types and smaller zircons grains, less than 100 µm in length (Flowers et al, 2010;Kaczmarek et al, 2011;MacDonald et al, 2013;Reddy and Timms 2010;Schwarzt et al, 2010;Timms et al, 2012b). In addition, some of the studies examined embedded zircon grains that were extracted from the sample by means of heavy mineral separation (e.g., Kaczmarek et al, 2011;Moser at al., 2011;Reddy et al, 2009;Schwartz et al, 2010;. During the conventional procedure of extracting larger grains by classical mineral separation techniques, the context of host minerals and the immediate environment is lost, which restricts interpretations and conclusions.…”

“…Arrays of edge dislocations with the same Burgers vector form tilt walls, whereas arrays of screw dislocations form twist walls. All symmetrically equivalent crystallographic directions and planes which are orthogonal may represent valid glide systems (Roters et al, 2010 Leroux et al, 1999;Reddy et al, 2007;Kaczmarek et al, 2011;). These two relevant glide systems could be labeled as one slip system: < 100 > { 010 }.…”

“…In the past, the common explanation for low-temperature diffusion in zircon was the effect of self-irradiation that causes metamictization and thus induces/enhances volume diffusion (Cherniak et al, 1991;Cherniak and Watson, 2003). Recently, a number of authors found evidence for increased trace element diffusion in zircon due to crystal-plastic deformation (Erickson et al, 2013a, b;Flowers et al, 2010;Grange et al, 2013;Kaczmarek et al, 2011;MacDonald el al., 2013;Moser et al, 2009Moser et al, , 2011Nemchin et al, 2009;Piazolo et al, 2012;Reddy et al, 2006Reddy et al, , 2007Reddy et al, , 2009Reddy and Timms, 2010;Schwartz et al, 2010;Timms et al, 2006Timms et al, , 2011Timms et al, , 2012a. These authors have shown that crystalplastic deformation can dramatically affect the content of trace elements in zircon domains and can therefore cause isotopic system resetting.…”