Reconstrucción paleoclimática y de la productividad del registro sedimentario de la provincia ZTuna aproximación a los procesos diagenéticos

Resumo

This study provides a reconstruction of the climatic changes and palaeoproductivity, as well as a diagenetic interpretation of three piston cores extracted at the Transitional Zone (TZ) province of the Galicia Continental Margin. The combination of high-resolution geochemical and magnetic data, along with a robust age model for the last 170 cal ka BP, allowed the climate reconstruction of the TZ delimiting the last eleven Heinrich Stadials. The calculated low sedimentation rates identified con- densed sequences of Heinrich Layers during MIS2, MIS 3 and MIS4. The palaeoproductivity indicators used – total organic carbon (TOC), biogenic barium and organic phosphorus (Schoepfer et al., 2015) - allowed to characterise the variations of the biological pump and biogeochemical cycles in the TZ attending to the glacial/ interglacial cycles. Numerous oxidation fronts were identified, indicating that the early diagenesis has not reached the steady-state, because the redoxcline has not achieved the deeper equilibrium as a consequence of erosional processes that caused the continuous oxygenation of the sedi- ment. Thus, the results provide detailed information about the diagenetic activity and marine palaeoproductivity attending to the palaeoclimatic conditions during the late Pleistocene and the Holocene in the TZ.