Rifting in an oceanic environment with subsequent redeposition including processses from hydrothermal through sedimentary /near-shore marine to regional metamorphic . See e.g. the Kalahari Mn ore field as a giant ore deposit and Mn nodules as an intermediate low-grade-large tonnage deposits and the hot-spot islands of the Canary Islands as some sort of a Mn proto-ore.
See:
DILL, H.G., PÖLLMANN, H. and TECHMER, A. (2013) 500 Million years of rift- and unconformity-related Mn mineralization in the Middle East: A geodynamic and sequence stratigraphical approach to the recycling of Mn.- Ore Geology Review 53: 112-133.
DILL, H.G., BUZATU, A., BALABAN, S.-I. and RÜSENBERG, K. A. (2023) A mineralogical-geomorphological terrain analysis of hotspot volcanic islands -The missing link between carbonatite- and pegmatite Nb-F-Zr-Li-Be-bearing REE deposits and new tools for their exploration (Canary Islands Archipelago, Spain).- Ore Geology Reviews: 163, 105702 https://doi.org/10.1016/j.oregeorev.2023.105702 (open access)
DILL, H.G and RÜSENBERG, K. A. (2023) Marker minerals in volcanics and xenoliths—An approach to categorize the inferred magmatic rocks underneath the present-day volcanic landscape of Tenerife, Spain (NW African Rare Mineral Province).- Minerals: 2023, 13, 1410. 1-56, https://doi.org/10.3390/min13111410 (open access)