Unmixing Progradational Sediments in a Southwestern Caribbean Gulf through Late Holocene : Backwash of Low-Level Atmospheric Jets

Abstract

ABSTRACT: In the last few years there has been considerable interest in the assessment of the role of tropical seas in driving paleoclimate. Despite this interest, little is known about the evolution of progradational sediments near the Panama Isthmus during the late Holocene. This paper shows the dispersion assessment of fluvial sediments into a gulf from the southwestern Caribbean on a decadal-centennial scale as recorded in three sediment cores spanning between 300 and 960 6 35 calibrated YBP. According to end-member modeling of size classes, sediments largely comprised clay, clayey fine silt, and silty mud that flocculated by differential settling. Coarsened facies were consistent with enhanced fluvial discharge owing to increased precipitation in the circum-Caribbean. Remarkably, decreased fluvial discharge into the gulf due to aridity in the Caribbean was modulated by oceanic moisture conveyed by the low-level atmospheric jets of Panama and CHOCO. Fluvial sediments may surely fail to contribute to shoreline stability because of muddy hinterland lithology