Subseafloor mineralisation in rocks of the Matakaoa Volcanics around Lottin Point, East Cape, New Zealand

Abstract

Matakaoa Volcanics include basalts, dolerite, gabbro, and minor undersaturated alkaline plutonics; sedimentary bands or lenses are intercalated within the igneous rocks. Mineralisation occurs at 4 localities in the Lottin Point area, always associated with sediments, and distributed along eastnortheast trends. The mineral associations are manganese oxides, pyrite-sphalerite-galena-chalcopyrite with traces of gold and silver in barite gangue, andpyrite-chalcopyrite. The mineralisation is the result of exhalative precipitates from submarine hot springs, in places accompanied by biological activity and deposited with sediments between lava flows in a subseafloor environment. The economic potential is insignificant because of very limited strike extent.