Geological reconnaissance of coastal areas in the northern Malaita in the Solomon Islands with a view to researching occurrences of alnöit with high-pressure ultra-high pressure xenolites from the deep cap

Geological reconnaissance of coastal areas in the northern Malaita in the Solomon Islands with a view to researching occurrences of alnöit with high-pressure ultra-high pressure xenolites from the deep cap

Associate professor Poul Martin Holm, Lic. Scient., The Institute of Geology, University of Copenhagen

On the island of Malaita in the Solomon Islands, there are types of rock that contain unique minerals (marjorite and silicate perovskite) that have been brought up to the surface from unusually great depths in the Earth. These minerals can give important direct information on the chemical environment obtaining at these depths, and can thus contribute to solving the riddle of the formation and development of the cap, as well as the dynamic processes that take place in the inner parts of the Earth. The few geological deposits of these unique rock types that have been identified so far are limited to areas close to the island’s only road suitable for travel by motor vehicle. The rest of the island has no roads and is accessible only with difficulty. The Galathea 3 expedition makes it possible to carry out geological reconnaissance from the sea, and thus facilitates the identification of new, undiscovered deposits of these types of rock. In addition, the fast rubber dinghy of the Galathea makes it possible to land on the shores of some of the island’s inaccessible areas and thus makes it possible to make considerable collection of rock samples from these areas, which will be brought back to the University of Copenhagen for geochemical analysis. The binocular oversight microscope onboard the Galathea 3 permits researchers to perform in situ examination of rocks and minerals, which will make the geological fieldwork on the island more effective.