1507 / 2024-09-27 20:32:58

DIAGENETIC PROCESSES AND DOLOMITIZATION IN DEEP MARINE CARBONATES: INSIGHTS FROM CORE U1576 OF WALVIS RIDGE, IODP 391

Diagenesis,Early dolomitization,IODP Expedition 391,kinetic model of marine carbonate diagenesis,stronitum partition coeficient,steady state diagenesis

Session 8 - Modern and past processes of ocean-atmosphere-climate interactions in the low-latitude Pacific and Indian Ocean

This study investigates the diagenetic alterations in deep marine carbonate sediments of Walvis ridge of Tristian de Cunha hotspot region, with a particular focus on the dolomitization observed in Core U1576. Using a kinetic model that incorporates the strontium partition coefficient (KSr) and precipitation rates (Rp), we assess how these parameters influence calcite recrystallization and dolomite formation in marine sediments. Results from cores U1575, U1576, U1577, and U1578 highlight significant spatial variations in KSr, linked to changes in calcite precipitation dynamics and diagenetic environments. Notably, Core U1576 exhibits a high correlation between KSr and Rp (R² = 0.69), where dissolution rate Rd exceeds Rp (non-steady state) in deeper sections of the core. The bottom section of the same core showed presence of dolomite, indicating that the higher dissolution rate than recrystallization rate promotes dolomite formation with the lowest strontium incorporation. Our findings underscore the importance of thermodynamic energy barriers in dolomite formation within non-steady-state diagenetic systems of the ridge sediment, providing a comprehensive view of how deep-sea carbonate diagenesis can be used as a proxy for past oceanographic conditions. These insights are critical for advancing our understanding of marine geochemistry, particularly in regions of active sedimentation, volcanic matter intrusion and carbonate alteration.