Paleoflow history determined from mudwave migration: Argentine Basin

Abstract

Abstract A mudwave site in the central Argentine Basin was investigated to determine its present and past mudwave activity. Site 7, on the south flank of the Ewing Drift in the northern Argentine Basin, has mudwaves that have migrated primarily throurgh preferential deposition, resulting in a relatively complete sediment on both wave flanks. Thus a history of mudwave migration can be determined for this site. The mudwave studied shows migration from before 420 ka until 32 ka, with paleocurrent speeds near 15 cm s−1 and with minor changes in current speeds around 110–120 ka. The wave migration rate became less from 32 ka to 26 ka with paleospeeds of 9 cm s−1. Wave migration ceased about 26 ka, suggesting a cessation in flow. This study indicates that bottom water velocities at this site were high during the last glacial period. but dropped abruptly near the end of the last glacial period. However, bottom current velocities appear to have been moderately high during the previous interglacial period (∼ 120 ka), suggesting that there is no simple relationship between flow speed and paleoclimate at this site.