A MID TO LATE HOLOCENE ULTRA HIGH-RESOLUTION FORAMINIFERAL BIOFACIES RECORD FROM IODP EXPEDITION 318: WILKES LAND, ADELIE TROUGH, ANTARCTICA
Preliminary results show generally low foraminiferal abundances and diversity throughout the study interval. Over 30 species of benthic foraminifers have so far been identified, with Neogloboquadrina pachyderma sinstral representing over 98% of the planktonic foraminifers observed. Planktonic foraminiferal abundances are generally higher below 49.2 mbsf (3.7 kyr). The agglutinated Trochammina spp. species are generally the dominant taxa throughout the samples examined. Cibicides spp. abundances are higher between 27 to 60 mbsf (2.7 to 4.7 kyr) and again above 10 mbsf (<1,000 kyr). Epistominella spp. are more abundant between 47.8 and 75.7 mbsf (3.6 and 5.5 kyr). Globocassidulina and Quinquelculina spp. are also more abundant below 70 mbsf (~5.2 kyr).
The higher abundances of calcareous benthic forms are interpreted to represent higher oxygen levels and less corrosive waters for the bottom waters. This suggests better ventilated bottom waters may have been occurring during the Mid Holocene warming. The high dominance of agglutinated forms in the upper part of the section suggests that bottom waters during the Neoglacial (3.5 kyr- present) were more corrosive and contained lower oxygen content.