Submarine hydrothermal metallogenesis associated with the collision of two plates: The Southern Aegean Sea region

Abstract

Abstract The geochemistry of sediments from the Southern Aegean Sea demonstrates that the active tectonics in the Hellenic Arc-Trench system favor hydrothermal mineralization processes involving leaching of oceanic crust. The distribution and geochemical behavior of Mn, Fe, Cu, Zn, P and Ba indicate a hydrothermal influence: i) at plate boundaries such as the Pliny and Strabon Trenches; ii) in fore-arc basins such as Maleas, Iraklion and Karpathos; iii) on the Island Arc. All fore-arc basins having greater Mn enrichments than the trenches are also characterized by higher heat flow values. The greatest Mn enrichments occur at Maleas Basin where a Mn dispersion halo is recognized. This basin is very tectonically active, with the largest group of normal faults, along the planes of which magmatic material was injected, and the highest heat flow values in the Sea of Crete. It also falls in the Eastern Mediterranean Zone of high seismic activity. Because the Fe-Mn sediments identified in the above geotectonic units are the end-members of the hydrothermal fractionation sequence known from areas where leaching of oceanic crust occurs, it is suggested that other members of the sequence such as metal Sulfides may be found. Significant geochemical anomalies of Pb and Zn found in areas of high heat flow and on lines of normal faulting are considered to be traces of the presence of metal sulfides.