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The new global Integrated Ocean Drilling Project will include drilling in previously undrilled aquatories of continental shelf. In the circum-Baltic countries international joint research for preparation of drilling at the Baltic Sea is planned.The first target is the oldest supracrustal complexes of Palaeoproterozoic to Phanerozoic bedrock.The present project is intended to co to the pre-drilling research and design of the drilling program. The investigators involved have a long-lasting experience of circum-Baltic geological cooperation in the Baltic Sea research and trans-Baltic correlation. Compared to previous studies, the main targets of the present project are previously weakly studied structures and rocks of the seabed. Our preliminary conclusion is that the present Baltic Sea depression formed finally in the Late Cenozoic in the central part of the Svecofennian (1.9-1.8 Ga) Crustal Domain as a result of regional and local erosion, glacial exaration and imcomplete post-glacial rebound of glacioisostatic depression in the conditions of soft epirogenic and differentiated crustal movements. However, it was found, that the main depression of the Baltic Sea and Gulf of Bothnia is nested within a Palaeoproterozoic to Palaeozoic zone of crustal weakness cross cutting the uniform extremely thick (45-65 km) and stable Svecofennian crustal domain (1.9-1.8 Ga in age). Within the Baltic-Bothnian Belt (BBB), Subjotnian (1.65-1.5 Ga) igneous and sedimentary, Jotnian (1.4 Ga) sedimentary and Lower Palaeozoic (0.6-0,4 Ga) sedimentary suites are abundant either as intrusions in the or fill tectonic depressions in it. Geology of BBB differs significantly from the surrounding mainland. However, practically no specialized complex studies of petrology, age, structure and evolution of oldest suites building the Baltic seabed has been carried out. As there is very few drill cores available such studies have to be based on the outcrops and drill cores along the seashores, erratic boulders dispersed by Quaternary glaciers, suites trapped in tectonic grabens and fragments in breccias of crater fillings. In collections of previous studies, a considerably large number of relevant samples is stored. Using lithological, mineralogical, geochemical, isotopic dating and petrological methods, geophysical studies and structural modelling we are going to study the formation and subsequent changes of rock and minerals, and as a whole, the history of formation of the oldest post-orogenic and platform suites in the area of junction of Baltic proper and its gulfs, and of the entire BBB. Two PhD and one MSc. students participate the project. |