Does second phase content control the evolution of olivine CPO type and deformation mechanisms? A case study of paired harzburgite and dunite bands in the Red Hills Massif, Dun Mountain Ophiolite

Why the pounamu? Low- to medium grade metabasites and metaultrabasites of New Zealand from a geoheritage perspective

“…Most probably local shear is responsible for the felted fabric of amphiboles. The Dun Mountain Ophiolite Belt (Figure 1) has been metamorphosed in western Southland and pounamu from this belt is found along the eastern and northern edge of Fiordland [38,39]. The Anita Bay Dunite near Milford Sound is a small but highly prized source of pounamu.…”

Mantle peridotites of ophiolites rarely preserve reliable records of paleo-oceanic lithospheric mantle

“…Olivine in mantle peridotites of ophiolites has been extensively studied by numerous authors, particularly regarding deformation textures (e.g., Linckens et al, 2011aLinckens et al, , 2011bHiggie and Tommasi, 2012;Hidas et al, 2021;Saveliev et al, 2021Saveliev et al, , 2022Shao et al, 2021), serpentinization (e.g., Etiope et al, 2011;Frost et al, 2013;Huang et al, 2017a;Gahlan et al, 2018;Nozaka, 2018), and major and trace elemental compositions (e.g., Su et al, 2019;. Although our knowledge of these olivine crystals is still mostly restricted to high-temperature partial melting and low-temperature alteration, elemental distributions in these olivine grains might have been modified by sub-solidus elemental exchange with spinel or reaction with melts/ fluids (e.g., Zhou et al, 1996;Xiao et al, 2016;Rollinson, 2019;Su et al, 2019;Xiong et al, 2020a;Xu et al, 2023).…”

Microstructural Relationship between Olivine and Clinopyroxene in Ultramafic Rocks from the Red Hills Massif, Dun Mountain Ophiolite

“…The volume of dunite is dominant and the olivine grains are equigranular [8,18,42]. The dominant strike direction is along the N-S, with (sub)vertical lineations (Figure 1b).…”

“…Wehrlite is the most common peridotite with clinopyroxene, which is generated by either a melt-rock reaction or interaction with SiO 2 -undersaturated magmas [4][5][6]. Although the solid second phase may inhibit the development of the olivine crystallographic preferred orientation (CPO) [7,8], wehrlites in different areas and geological environments can generate various olivine CPO types (B, E, and AG-type; [9][10][11]). In comparison, (010) [001] is the most common clinopyroxene CPO type [12][13][14] whereas it is not dominant in wehrlite or other peridotite types [15][16][17].…”