Interpretation of Late-Pleistocene/Holocene Transition in the Sea of Marmara From Geochemistry of Bulk Carbonates


Liu Y., Lu H., Yin X., Ruffin L., Cagatay M. N. , Yang H., ...Daha Fazla

GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS, 2019 (SCI İndekslerine Giren Dergi) identifier identifier

  • Basım Tarihi: 2019
  • Doi Numarası: 10.1029/2019gc008364
  • Dergi Adı: GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS

Özet

Isotopic, mineralogical, and elemental analyses have been conducted for the geochemical characteristics of the bulk carbonates in the sediment cores from the Western High and cinarcik Basin in the Sea of Marmara to investigate the authigenic, biogenic, and detrital components and their possible use in paleoceanographic studies. The Western High is a relatively shallow (-500 to -800 m) compressional area characterized by relatively low sedimentation rates (30-40 cm/Kyr), whereas the cnarcik Basin is a deep (similar to 1,250 m) transtentional area represented by high sedimentation rates (>1 m/Kyr). Both Sr-87/Sr-86 and delta O-18 of bulk carbonates from the Western High exhibit significant variations, increasing steeply from Sr-87/Sr-86 of 0.708437 to 0.708916 and delta O-18 of -3.2 parts per thousand Vienna Pee Dee Belemnite (VPDB) to 0.1 parts per thousand VPDB, indicating the incursion of the Mediterranean seawater after the last glacial and reflected in the change from lacustrine to marine environment. However, bulk carbonates in the core from the cinarcik Basin have comparatively uniform values of Sr-87/Sr-86 (similar to 0.708845) and delta O-18 (similar to 0.0 parts per thousand VPDB), implying that this core did not experience the lacustrine/marine transition. In the Western High, delta C-13 values up to +24.3 parts per thousand VPDB at 400 cm below seafloor reveal the mineralization of heavy CO2, providing independent evidence for the subsurface biodegradation of petroleum. While in the cinarcik Basin, delta C-13 values of bulk carbonates were relatively constant (approximately -2.94 parts per thousand VPDB). The high delta C-13 values of bulk carbonates from the Western High reflect the dissolution of primary carbonates as a result of the local acidic environment and precipitation of authigenic carbonates later, supported by mineralogical and elemental results.