Earth is unique among the planets of our solar system. This is not only due to its multiform biosphere, but also because its surface is a constantly changing environment. Fundamental factor behind these characteristics is the Earth’s dynamic and hot interior which shapes and moves continents and releases water and carbon dioxide – the building blocks of life – via magmatism. Studying Earth’s interior and magma generation (igneous petrology) are thus some of the most important fields of research in geology.

Anorogenic magmatism is defined as the crystallization of magma on (volcanism) or in (plutonism) the crust in a tectonic setting that is unrelated to collision of lithospheric plates and formation of mountain belts. Anorogenic magmatism occurs when lithospheric plates rupture: as a result the Earth’s mantle upwells and partially melts sometimes forming considerable quantities of magma. In some occasions, such ruptures have led to dispersal of continents and formation of new plate boundaries. The ultimate origin of anorogenic magmatism has been and still is one of the most challenging questions in igneous petrology.

Dronning Maud Land in Antarctica (Figure 1) has turned out to be a fruitful area to study anorogenic magmatism. Nunataks that break through the continental ice sheet are void of vegetation and show evidence of multiple anorogenic magmatic events in the past. Youngest of them at ~180 Ma resulted in the emplacement of the Karoo continental flood basalts (CFBs; Figures 2 and 3) and related volcanic and plutonic rocks. The emplacement of Karoo CFBs was followed by the dispersal of the Gondwana supercontinent and generation of smaller continents that we presently recognize as Africa, South-America, Australia, and Antarctica (Figure 2). The Karoo CFBs once covered an area of ~2 000 000 square kilometers with an average thickness of one kilometer – their original volume corresponds to about 100 times that of the Baltic Sea waters.

The oldest anorogenic igneous rocks of Dronning Maud Land are over 1000 million years old and are related to the dispersal of an ancient Rodinia supercontinent, which preceded the formation of Gondwana. These rocks have largely eroded away, however, and only the crystallized magma chambers of ancient giant volcanoes, rapakivi-granites (Figure 4), remind us from anorogenic events of those times.

Largest anorogenic eruptions had a significant impact on the climate and biosphere and the subsequent evolution of the planet’s surface to its present state. But how is it possible to generate such vast amounts of magma in general? What kind of mantle materials were the initial sources for the melts, and at what depths and temperatures?

Finnish geologists have visited Dronning Maud Land since 1989 – the latest expedition took place during the Antarctic summer 2007–2008 (Figures 5 and 6). The Finnish Antarctic research station Aboa at Vestfjella (S73°03, W013°25; Figure 1) has served as a base for the expedition teams.

Geological studies have concentrated on the ~180 million-year-old remnants of the Karoo CFBs (Figure 3) and related dike and plutonic rocks (Figure 7). Vestfjella hosts a versatile collection of distinctly evolved flood basalts and some of the most extraordinary Karoo-related rock types, ferropicrites, which have avoided lithospheric contamination and provide direct geochemical information from the ultimate sources of the CFBs (Figure 8). Rare alkaline dike rocks, which are reminiscent of the kimberlites of South-Africa, contain crustal xenoliths that were picked up by the host magmas during their rapid journey towards the Earth’s surface (Figure 9). These xenoliths have led us to the secrets of the Precambrian basement, over billion years into the origins of the Rodinia supercontinent. The rapakivi-granites (Figure 4) that are related to the break-up of Rodinia have also been the subject of our research.

The foundations of our research have been built on broad international collaboration and the utilization of up-to-date geochemical and geochronological analyzing methods (Figure 10). The research is funded by the Academy of Finland and the Finnish Graduate School in Geology. Our studies at Dronning Maud Land have resulted in two Doctoral theses (two in preparation) and six Master’s theses (two in preparation) so far. Results have been published in several focal international journals of the field (see Publications).