URSEIS. Transecting the Uralide Orogen Database and state of the art

The Ural Mountains of central Russia separate the ancient core of Europe, the East European Craton, from the more easterly terranes of Siberia and Kazahkstan. Together with the Caledonian, Appalachian and Variscian orogenic belts, the Urals compose the Paleozoic framework of the old craton. Todays Mountains are largely a Tertiary feature. The Uralide orogen extends far eastwards, forming the basement of the Mesozoic hydrocarbon bearing formations of the West Siberian Basin. The 3000 km long mountain belt is a unique natural laboratory with many key features that are important for our understanding of Paleozoic collisional orogeny. Comparison of the Uralides with the other related Paleozoic orogens will provide new insight into the processes of pre-Mesozoic plate tectonics. The existing database indicates the Urals are remarkable for their preservation of a continental root, the orogen having apparently suffered less post-orogenic collapse than most other Paleozoic mountain belts. Nevertheless, extension must have contributed significantly to the preservation throughout the belt of some of the world's most complete ophiolites and island-arc volcanic suites (along with associated mineralizations), juxtaposed over very high-P blueschists and eclogites. Other Paleozoic orogens have been re-equilibrated to normal crustal thicknesses during late- to post-orogenic processes. Such mechanisms of uplift and extension are also demonstrated in young orogens (e.g. Himalaya, Alps). The existence or appearant preservation of a thickened crust beneath the Uralides represents a fundamental problem in the understanding of orogenic processes. The young history of the Urals, following extensive Mesozoic transgression and erosion, is of particular interest in view of the reportedly high (2mm/yr) uplift rates and widespread evidence of Tertiary (Recent?) tectonism. Historical seismicity is reported to be concentrated to the Middle Urals, apparently related to a compressional stress regime. Establishing the relationship of the crustal roots to deep structures in the subcrustal lithosphere and astenosphere and understanding the development of these major structures in time is fundamental for full interpretations of the dynamic evolution of the Urals. A wide range of new interdisciplinary investigations of the Uralide orogen are proposed here in the form of a collaborative European-American initiative, the scope of which has never been previously attempted for the continental lithosphere. Geoscientists from institutions all over Europe will work together with N.I.S. colleagues on key aspects of the mountain belt. COCORP-DEKORP type deep seismic reflection (CDP) profiles across the Southern Urals are a key experiment for relating shallow to deep structures. (orig.)Available from TIB Hannover: RR 6134(95/01) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany); European Science Foundation (ESF), 67 - Strasbourg (France)DEGerman