Sr Isotope Composition in Inland Seas of the Mediterranean—Black Sea Belt

摘要

Chemostratigraphic correlation is based on a statement about the uniformity of ~(87)Sr/~(86)Sr in oceans and all adjacent seas at each moment in time [1—3]. This statement is based on the fact that the residence time of Sr in the ocean significantly (by three orders of magnitude) exceeds the time necessary for seawater mixing [4]. In modern oceans this fact is confirmed by coincidence of the ~(87)Sr/~(86)Sr ratio with that of beach shells [2], shallow foraminifer mud on island uplifts [5], and abyssal carbonate sediments from DSDP wells [6]. However, most carbonate rocks preserved in the geological record are sediments of marginal and inland seas, but not open oceans. In the opinion of some researchers of the Precambrian, water exchange between shallow inland seas and the ocean was complicated by narrow straits and shoals, and thus it would have been insufficient for leveling of the ~(87)Sr/~(86)Sr ratio in inland seas to the oceanic ratio. Thus, the legiti-%Institute of Precambrian Geology and Geochronology, Russian Academy of Sciences, Saint Petersburg, Russia;Institute of Precambrian Geology and Geochronology, Russian Academy of Sciences, Saint Petersburg, Russia;Institute of Precambrian Geology and Geochronology, Russian Academy of Sciences, Saint Petersburg, Russia;Institute of Precambrian Geology and Geochronology, Russian Academy of Sciences, Saint Petersburg, Russia;