Reply to comment by S.H. Büttner on “Evidence for Mesoproterozoic collision, deep burial and rapid exhumation of garbenschiefer in the Namaqua Front, South Africa ˮ

Abstract

Abstract We thank Prof. Buttner for his comments on our paper (van Schijndel et al., 2020), which allow us to clarify our work and the tectonic model we proposed for the eastern margin of the Namaqua Sector of the Namaqua Natal Metamorphic Province. The Kaaien Terrane forms a tectonic transition between the Kaapvaal Craton, Rehoboth Province, Kheis belt and the Archeachap Terrane of the Namaqua Sector and forms part of an NW-vergent foreland thrust sequence in the Namaqua Front (e.g. Cornell et al., 2006). The exact tectonic extent of the Kaaien Terrane is still unclear and it has recently been proposed to be part of the newly defined Kheis Terrane (Van Niekerk and Beukes, 2019). Buttner (2020) states that the tectonic model for the Mesoproterozoic evolution of Namaqua Sector which envisages the collision of multiple exotic terranes after the subduction of multiple oceanic basins (e.g. Miller 2012, and references therein) is outdated and newer tectonic models have been discussed in the literature in recent years. Bial et al. (2015a, 2015b, 2016) and Macey et al. (2018) propose a continental back-arc mobile belt setting to explain the high temperature and low pressure history of several terranes of the Namaqua Sector. For example, Pressure-Temperature time (P-T-t) paths describing the crustal evolution for the Kakamas Terrane by Bial et al. (2015a) suggest along-lasting high-temperature history (>650°C) at pressure not exceeding 5.5 kbar between ∼1350 Ma and