Open AccessInterpretation of Late‐Pleistocene/Holocene Transition in the Sea of Marmara From Geochemistry of Bulk Carbonates
Author(s) -
Liu Yujia,
Lu Hailong,
Yin Xijie,
Ruffine Livio,
Çağatay M. Namik,
Yang Hailin,
Chen Chunqing,
He Dong,
Zhu Zhenli,
Yalamaz Burak
Publication year - 2019
Publication title -
geochemistry, geophysics, geosystems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.928
H-Index - 136
ISSN - 1525-2027
DOI - 10.1029/2019gc008364
Subject(s) - geology , authigenic , geochemistry , seafloor spreading , holocene , seawater , structural basin , sediment , oceanography , sedimentary rock , geomorphology
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 Çınarcık 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 Çnarcık Basin is a deep (~1,250 m) transtentional area represented by high sedimentation rates (>1 m/Kyr). Both 87 Sr/ 86 Sr and δ 18 O of bulk carbonates from the Western High exhibit significant variations, increasing steeply from 87 Sr/ 86 Sr of 0.708437 to 0.708916 and δ 18 O of −3.2‰ Vienna Pee Dee Belemnite (VPDB) to 0.1‰ 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 Çınarcık Basin have comparatively uniform values of 87 Sr/ 86 Sr (~0.708845) and δ 18 O (~0.0‰ VPDB), implying that this core did not experience the lacustrine/marine transition. In the Western High, δ 13 C values up to +24.3‰ VPDB at 400 cm below seafloor reveal the mineralization of heavy CO 2 , providing independent evidence for the subsurface biodegradation of petroleum. While in the Çınarcık Basin, δ 13 C values of bulk carbonates were relatively constant (approximately −2.94‰ VPDB). The high δ 13 C 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.