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Our Earth, its minerals and ore bodies
Published in Odwyn Jones, Mehrooz Aspandiar, Allison Dugdale, Neal Leggo, Ian Glacken, Bryan Smith, The Business of Mining, 2019
Odwyn Jones, Mehrooz Aspandiar, Allison Dugdale, Neal Leggo, Ian Glacken, Bryan Smith
The fundamental basis for the theory of plate tectonics is the recognition that the outer layers of the Earth are made up of seven major and numerous minor moving plates (Figure 1.5). Each plate comprises a crustal component and the upper part of the upper mantle, known as the lithospheric mantle. This combination forms a rigid outer zone called the lithosphere and hence the lithospheric plates. The thickness of the lithosphere in areas dominated by oceanic crust is approximately 100 km compared to 200 km in areas dominated by continental crust. The layer of the upper mantle beneath the lithospheric mantle is known as the asthenosphere, which is weaker (plastic) and denser compared to the lithosphere. Hence the lithospheric plates essentially float on top of the asthenosphere and these changes enable the plates to move independently from the asthenosphere.
The geochemistry and petrogenesis of Carnley Volcano, Auckland Islands, SW Pacific
Published in New Zealand Journal of Geology and Geophysics, 2018
John A. Gamble, Chris J. Adams, Paul A. Morris, Richard J. Wysoczanski, Monica Handler, Christian Timm
The lithosphere of southern Zealandia comprises 20–30 km thick crust, coupled to lithospheric mantle whose thickness exceeds 100 km beneath the Southern Alps of New Zealand (Davey et al. 2007; Okaya et al. 2007) in broad agreement with estimations from mineral thermobarometry (Scott 2014, Scott et al. 2014). For the purposes of this contribution, we assume an average crustal thickness of 20–25 km and lithospheric mantle thickness of 80 ± 10 km, approximating to ∼2.5 ± 0.1 GPa at the boundary with convecting mantle.
Implications of upper-mantle seismicity for deformation in the continental collision zone beneath the Alpine Fault, South Island, New Zealand
Published in New Zealand Journal of Geology and Geophysics, 2018
Carolin M. Boese, Tim A. Stern, Konstantinos Michailos, John Townend, Calum J. Chamberlain
Three key factors have been inferred to control the rheological properties and therefore seismicity in the lithospheric mantle: temperature, water content and strain rate (e.g. Brace and Kohlstedt 1980; Chen and Molnar 1983; Bürgmann and Dresen 2008; Jackson et al. 2008; Chen et al. 2011). Linked to these, and also discussed below, are lithospheric thickness transitions and compositional, grain size and/or mineralogical heterogeneity in the mantle (Sloan and Jackson 2012, Inbal et al. 2016, Prieto et al. 2017).