Analysis of the Sedimentary and Geochemical Characteristics of Sedimentary Clastic Rock Samples from the Alpha–Mendeleev Rise

The paper presents new data on a comparative analysis of sedimentary rocks from the Mendeleev Rise (Shamshura Seamount), presumably, of the Triassic age with the Aptian sandstones obtained by the underwater sampling of the Alpha–Mendeleev Rise during expeditions in 2012, 2014, and 2016. The geochemical characteristics of rocks are very similar, and the data from different-age samples form common fields on various diagrams. Petrographic studies revealed that the sandstones of presumably Late Triassic age, as well as the sandstones of Chukotka and Wrangel Island, are dominated by fragments of shale and felsic effusives. The Aptian samples are dominated by mafic rock fragments. In addition, sharp differences are observed in the age spectra of detrital zircon populations, indicating fundamentally different provenances for the Triassic and Cretaceous sandstones on the Alpha–Mendeleev Rise. Samples from the Shamshura Seamount are characterized by populations similar to those from Triassic rocks of Chukotka and Wrangel Island, suggesting the presence of Triassic rocks in this part of the Mendeleev Rise.