Misael Díaz-Asencio, Vicente Ferreira Bartrina, Juan Carlos Herguera

Here we present new results on the spatial distribution patterns of lithogenic and biogenic components and sedimentation processes in the deep-water region (966-3741 m) of the southern Gulf of Mexico (sGM). A collection of 44 cores retrieved from the continental slopes and the abyssal plain were dated with the aid of accelerator mass spectrometry (AMS) 14C determinations on planktic foraminifera. We applied a mixing box model (MBM) to estimate the mixed layer age (TML), the mean sediment accumulation rate (Sm), and the mixing depth (XML) for each core. Observed ranges for these variables were Sm (3.4–17.7 cm/kyr), TML (393-6021 yr) and XML (2.4-24.3 cm). Deep-sea sediments in the study region fall into three main groups, which reflect the importance of the main sediment components, lithogenic and biogenic, and sedimentation processes at depth in the sGM. Cores clustered in Group 1 include most of the stations in the abyssal plain, show the oldest TML, relatively low Sm, and a relatively higher ratio between the carbonate and terrigenous components (mostly silt and clay). Group 2 cores were collected from stations in the transitional region, between the abyssal plain and the continental slopes, show relatively higher Sm, a younger TML and a relatively lower ratio between the carbonate and the terrigenous content than cores from G1. Group 3 cores were collected from different water depths on the continental slopes, show the highest Sm, younger TML, and the highest terrigenous content. These distinct groupings enabled us to recognize anomalous properties in certain cores, with implications on the local processes that alter their sedimentation processes at those sites. Our results highlight the importance of the terrigenous input to this basin, as one of the main controls of the burial rates with important implications on the possible fate of anthropogenic inputs and its sequestration in the deep-sea sediments of the sGM.

Deep-Sea Research Part I