Читать книгу Mantle Convection and Surface Expressions - Группа авторов - Страница 44

Recently, Merkel & Cordier (2016) reviewed slip systems in lower mantle and core phases. As such the following discussion will briefly review textures and slip systems in lower mantle phase but will mostly focus on more recent developments. For a more detailed discussion of studies on slip systems prior to 2016 and for a figure showing the relationship between crystal structures and slip systems, the reader is referred to the review by Merkel & Cordier (2016). A summary of experimentally inferred slip systems of lower mantle phases is given in Table 2.1.

Table 2.1 Summary of inferred slip systems in the major lower mantle phases and the conditions under which they are expected to dominate based on experimental data. See text for details of the experiments.

Mantle phase	Slip system	P‐T conditions
Ferropericlase	{110}<1‐0>	High P, low T
	{100}<011>	High P, high T
Ca‐Perovskite	{110}<1‐10>	High P low T
Bridgmanite	(001) in [100], [010] or<110>	P < ~55 GPa, low T
	(100)[010]	P > ~55 GPa, low T
	(100){001]	High P, high T
Post‐Perovskite	(001)[100]	High P, low T and high P, high T
	(010)[100] and (010)<u0w>	CalrO3, high P, low T, and high P, high T

In compression studies texture development is typically represented by inverse pole figures (IPFs) of the compression direction (Figures 2.4–2.5). IPFs show the probability of finding the pole to a lattice plane in the compression direction (i.e., the relationship between one sample direction and all crystallographic plane normals). Texture intensity is typically given in multiples of random distribution (m.r.d.) or multiples of uniform distributions (m.u.d.) where an m.r.d. or an m.u.d. of 1 is random and a higher or lower number represents a greater or fewer number of orientations, respectively. In cases where the deformation geometry is more complex than compression (e.g., simple shear), it common to represent textures with pole figures (Figure 2.4g). Pole figures show the orientation of a specific lattice plane normal to the sample coordinate system (i.e., one or a few specific lattice planes to all sample directions).