The Earth's evolution from a chunk of largely molten rock to a living blue planet began already over 4,500 million years ago. The principal driving force in this transformation has been the geological cycle of material through magmatic and tectonic processes.
The young Earth was different from our present world in several fundamental ways. The origin of the Moon, the onset of plate tectonics, the rise of the continents, and the formation of the oxygen-rich atmosphere and hydrosphere all took place billions of years ago.
The present stable bedrock of Finland has a fiery past. The oldest, Archean part of the bedrock in Eastern Finland started to form nearly 4 billion years (Gyr) ago during times of fierce bombardment by meteoroids and asteroids and is among Earth's oldest continental regions. Our studies examine the composition, structure, and age of the Archean rock types of eastern and northern Finland in order to unravel the enigmatic geological evolution of the Early earth. The conversion of basaltic crust into a thick, buoyant felsic crust has been a crucial event in the Earth’s evolution during the Archean Eon (4.0–2.5 Gyr). We have investigated formation of felsic crust using structural and geochemical analyses of Archean rocks in northern Finland, in the Lapland-Kola Province of Arctic Fennoscandia. Our results support the view that primitive plateau basalts were converted to felsic crust through mid-crustal partial melt segregation processes.
The Bundelkhand craton in central India consists mainly of abundant granitoids formed ca. 2.5 Gyr and enclosed rafts of TTGs (tonalite-trondhjemite-granodiorites) up to 3.5 Gyr old. Therefore, the Bundelkhand craton is a key locality for studies on Archaean crustal growth and the emergence of multisource granitoid batholiths that stabilised a supercontinent at 2.5 Ga. We aim to provide new insights into the role of juvenile versus crustal sources in the evolution of the various rock types of the Bundelkhand craton. Overall, our studies support a change from early mafic sources to strong crust-mantle interactions towards the Archean-Proterozoic boundary, probably reflecting the onset of supercontinent cycles.
Every 20-30 million years or so, millions of cubic kilometers of magma form underneath Earth's crust. They settle within the crust as widespread magma intrusions and erupt as floods of lava on the surface. Such large igneous provinces (LIPs) manifest culmination events of Earth history - they frequently relate to the breakup of continents and they are the primary cause of global mass extinctions. The formation of LIPs is widely ascribed to mantle plumes, hot currents ascending from Earth's deep interior.
The Karoo LIP was emplaced on the juxtaposed land masses of Africa and Antarctica during the early stages of the breakup of the Gondwana supercontinent at Jurassic times ca. 180 million years (Myr) ago. About 2,000,000 km3 (~100 times the volume of the Baltic Sea) of basaltic magma was emplaced in and on to the crust in a time scale of a few million years. Together with our coworkers, we collect samples of these Jurassic magmatic rocks from Antarctica and Africa and investigate the causes and consequences of the highly volumionus magmatic events
The formation of the mafic and silicic rocks of the rapakivi association commenced ca. 100 Myr after the termination of the Svecofennian orogenic activity at ca. 1650 Myr ago. The mid-Proterozoic rapakivi-related igneous province of southern Finland is formed of several rapakivi granite plutons, a few mafic plutons, and several silicic and mafic dyke swarms. Whereas the source of rapakivi granite magmas has been widely associated with melting of young continental crust formed during the Svecofennian orogen, the source of mantle-derived mafic magmas has remained enigmatic. Our studies utilize chronological and geochemical methods to establish the nature of the mantle source that produced widespread mafic magmatism in the rapakivi magma province.
Meteorites are pieces of planetary bodies that have fallen on Earth. Primitive chondrite meteorites provide critical observational evidence on the nature and composition of the Solar Nebula 4,55 billion years ago, whereas achondrites and iron meteorites are samples of variably evolved asteroids and planets and thus elucidate planetary differentiation.
The nature and evolution of planetary bodies can be also studied experimentally. As a part of the ongoing BeniColombo mission, we aim to assess the magmatic processes of the planet Mercury by laboratory melting experiments under the highly reducing conditions that are likely to prevail on the first rock from the Sun.