Zircon geochronology of bottom rocks in the central Arctic Ocean: analytical results and some geological implications

• Main Authors: Grikurov, Garrik, Petrov, Oleg, Shokalsky, Sergej, Rekant, Pavel, Krylov, Alexey A., Laiba, Anatoly, Belyatsky, B. V., Rozinov, Mikhail, Sergeev, Sergej
• Other Authors: Stone, David B., Grikurov, Garrik E., Clough, James G., Oakey, Gordon N., Thurston, Dennis K.
• Format: Book Part
• Language: English
• Published: Geophysical Institute, Univ. of Alaska 2014
• Subjects: Amerasia Basin; Arctic; Arctic Ocean; Mendeleev Rise; Lomonosov Ridge
• Online Access: https://oceanrep.geomar.de/id/eprint/28578/; https://oceanrep.geomar.de/id/eprint/28578/1/Grikurov_2014_ICAM6.pdf; http://www2.gi.alaska.edu/icam6/chapters/Chapter10.pdf

In the past few years sampling of deepwater seabed gained an increasingly important role in studying geological structure of the Arctic Ocean. A common concept of virtually uninterrupted pelagic drape in the Amerasia Basin and exclusively ice-rafted nature of all clastic components that occur in bottom sediments was challenged by recent discoveries of bedrock exposures in the sea floor, while correlation of results of analytical study of bottom samples collected by the Russian expeditions in 2000, 2005 and 2007 with bathymetric environments at respective sites suggested that certain dredged and cored coarse rock fragments appeared meaningful for bedrock characterization if even the source sub-pelagic outcrop was not positively documented. The first results of age determinations of detrital zircons that were extracted from coarse fragments of lithic sedimentary rocks resting on the seabed and in the immediate sub-bottom, as well as of zircons from fragments of magmatic/metamorphic rocks and of zircon grains separated directly from sub-pelagic unlithified sediments are in agreement with published interpretations of the Lomonosov Ridge bedrock as composed of Mesozoic terrigenous sequences; the presence of an older Neoproterozoic(?) – Early-Middle Paleozoic basement is also possible. The Mendeleev Rise bedrock, too, is believed to mainly consist of Paleozoic-Early(?) Mesozoic sedimentary superstructure that may locally rest on the Earliest Paleozoic or even older units. Basaltic rocks likely to originate from the High Arctic Large Igneous Province (HALIP) has not so far been found among the collected fragments but limited loose zircon grains probably derived from broadly contemporaneous magmatic products were recorded in sub-pelagic sediment along with dropstones of variably metamorphosed Precambrian mafic and granitoid rocks. INTRODUCTION Great progress in acquisition of new bathymet-ric and geophysical data relevant to understanding the geological structure and history of the Arctic Ocean, including the tectonic ...