Baltica (East European Craton) and Atlantica (Amazonian and West African Cratons) in the Proterozoic: The pre-Columbia connection

It is generally recognized that the Columbia (Nuna) supercontinent was assembled during the Paleoproterozoic (2.1-1.8 Ga) planetary-scale orogenic events. Paleomagnetic and palinspastic modeling proposes more than a dozen configurations for the Paleoproterozoic supercontinent. The locations and connections of the different continental blocks within this supercontinent remain controversial. The southern margin of Baltica either faced the open ocean or was connected with other paleocontinents such as Atlantica (Amazonian and West African Cratons) in different models. The large Volga-Don province (southwest Russia) has been proposed as the best candidate for connection with the Eburnean/Birimian (West Africa) and Transamazonian (South America) orogens before the Columbia assembly. Here we present a detailed comparison of the ages, compositions, and geochemical features of the voluminous metamorphosed mafic and felsic lithologies, pre- and post-collisional intrusions, and overlying sediments that formed in the interval 2.25-2.05 Ga in the orogens that suture the Archean blocks in Sarmatia, Volgo-Uralia, Amazonia and West Africa. The main events are limited by key complexes as follows: metavolcanic rocks (tholeiites, calc-alkaline, Na-rhyolites) of 2.23-2.12 Ga; pre-collision TTG 2.16-2.13 Ga and gabbro of 2.15-2.13 Ga; meta-sedimentary rocks (greywackes) of >2.10 Ga; coarse terrigenous sediments (conglomerates, sandstones) of 2.11-2.05 Ga; post-collision TTGs of 2.11-2.07 Ga, K-granites of 2.09-2.05 Ga and gabbrodiorites of ca. 2.07 Ga. Available age data allow us to draw a correlation among the Archean domains of Sarmatia, Volgo-Uralia (parts of Baltica), Amazonia and West Africa (parts of Atlantica). Our reconstruction provides a better framework for the crustal evolution and related metallogeny of these continental blocks, as well as the major orogens in the Proterozoic.