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Keywords:

  • Southeast South America;
  • Subtropical Shelf Front;
  • benthic foraminifera;
  • stable isotopes;
  • Holocene;
  • paleoclimate

Over the Uruguayan shelf and uppermost slope, the coalescence of northward flowing Subantarctic Shelf Water and southward flowing Subtropical Shelf Water forms a distinct thermohaline front termed the Subtropical Shelf Front (STSF). Running in a SW direction diagonally across the shelf from the coastal waters at 32°S toward the shelf break at ca. 36°S, the STSF represents the shelfward extension of the Brazil-Malvinas Confluence zone. This study reconstructs latitudinal STSF shifts during the Holocene based on benthic foraminifera δ18O and δ13C, total organic carbon, carbonate contents, Ti/Ca, and grain size distribution from a high-accumulation sedimentary record located at an uppermost continental-slope terrace. Our data provide direct evidence for: (1) a southern STSF position (to the South of the core site) at the beginning of the early Holocene (>9.4 cal ka BP) linked to a more southerly position of the Southern Westerly Winds in combination with restricted shelf circulation intensity due to lower sea level; (2) a gradual STSF northward migration (bypassing the core site toward the North) primarily forced by the northward migration of the Southern Westerly Winds from 9.4 cal ka BP onward; (3) a relatively stable position of the front in the interval between 7.2 and 4.0 cal ka BP; (4) millennial-scale latitudinal oscillations close to 36°S of the STSF after 4.0 cal ka BP probably linked to the intensification in El Niño Southern Oscillation; and (5) a southward migration of the STSF during the last 200 years possibly linked to anthropogenic influences on the atmosphere.