An international study of the lithosphere in the north-east European Precambrian craton (a co-venture of ILP/ESF-project EUROPROBE and IGCP-371 COPENA)

Project Information

EUROBRIDGE

Grant agreement ID: INTAS-94-1664

Start date 1 September 1995

End date 28 February 1998

Funded under

• International Association for the promotion of cooperation with scientists from the independent states of the former Soviet Union (INTAS), 1993-

Total cost € 0,00

EU contribution € 80 000,00

Coordinated by

Lund University
Sweden

Deliverables

EUROBRIDGE - an integrated study of the lithosphere in the north-east European Precambrian Craton (a co-venture of ILP/ESF-project EUROPROBE and IGCP-371 COPENA)

The European continent comprises an ancient northeastern half with thick, stable, cool continental crust, and a southwestern, younger half where the crust is thinner, warmer and more mobile. INTAS project 94-1664 EUROBRIDGE targeted the western part of ancient Europe in Belarus, the Ukraine, and adjoining parts of Russia. The mainstay of project work was a 1050 km long profile of deep seismic sounding. This was complemented by additional, interdisciplinary and internationally well integrated geological, geophysical, geochronological and geochemical studies. As a result, a wholly new image of the structure down to and beyond the Moho, the distribution of age provinces and the development history of the studied region created. By implication, these results are valid also for substantial parts of. the rest of the East European craton. Previous concepts of structure and development as well as previous maps of the Precambrian basement were largely found to be erroneous and have been replaced by new ones. The crust of ancient Europe is made up of several crustal segments which are either Archaean in age or were formed from Archaean crustal nuclei amalgamated during the earliest Proterozoic, ca. 2.3 to 2.1 billion ys.(Ga) ago. By 1.8 Ga, these crustal segments had collided to create the ancient core of Europe. Simultaneously, at the interface between the world ocean and developing ancient Europe, which at that time became part of a much larger supercontinent, a process of accretionary crustal growth commenced ca. 2.1 Ga ago. By continuous albeit episodic accretionary orogeny a belt of juvenile continental crust started developing. This process lasted for more than 500 million ys., ultimately shaping a Proterozoic crustal belt reaching 2000 km in width. From Belarus, the Ukraine and Scandinavia that accretionary belt can be traced to Greenland and across North America to still more distant Precambrian cratons like, for instance, present East Antarctica. INTAS project 94-1664 described the structure of the lithosphere at the boundary between the Fennoscandian and Sarmatian crustal segments, two of the principal components of ancient Europe, where continental crust was found to have been formed by subduction beneath Sarmatia. In the region farther northwest, in the NIS- and adjoining parts of the Proterozoic accretionary belt proper, integrated geophysical and geological study disclosed the existence of numerous igneous-arc type terranes with ages between more than 2.0 and less than 1.8 Ga. These had been accreted to each other and ultimately stacked against the older crust of Sarmatia.The individual terranes and terrane boundaries are marked by variations of Moho depth. As new accretionary crust continued to form at the growth rim of the accretionary belt, which by 1.7 to 1.6 Ga ago was far west in present southwestern Scandinavia, the somewhat earlier crust of the same kind to the east of the Baltic Sea was subjected to deformation, rifting and metamorphic alteration together with igneous activity of the rapakivi type. This created extremely complex structural patterns. An interesting project finding is that the Palaeoproterozoic major crustal boundaries once created continued to control the nature and siting of rifting, basin subsidence, crustal uplift as well as volcanic and hydrothermal activity throughout the Neoproterozoic and Phanerozoic. In our days, they still influence the patterns of neotectonics and recent heat flow. A wealth of data on deep structures, ages, igneous activity, and the regimes of metamorphism throughout time have been obtained during the project. The emerging lithospheric model of the western part of ancient Europe also has the capacity to serve as a strategical basis for future resource prospecting and the assessment of a range of geoenvironmental hazards.