Diatom datums and abundance in ODP Hole 188-1165B and 188-1166A sediments

• Main Authors: Whitehead, Jason M, Bohaty, Steven M
• Format: Other/Unknown Material
• Language: English
• Published: PANGAEA 2003
• Subjects: 188-1165B; 188-1166A; DRILL; Drilling/drill rig; Indian Ocean; Joides Resolution; Leg188; Ocean Drilling Program; ODP; Prydz Bay; Antarc*; Antarctic; Antarctica; East Antarctica; Ross Sea; Southern Ocean
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.780459; https://doi.org/10.1594/PANGAEA.780459

The biostratigraphic distribution and qualitative relative abundance of Quaternary-Pliocene diatoms from Ocean Drilling Program Leg 188, Sites 1165 (64.380°S, 67.219°E) and 1166 (67.696°S, 74.787°E) offshore from East Antarctica, are documented in this report. The upper ~50 meters below seafloor (mbsf) of Hole 1165B consists of brown diatom-bearing silty clay spanning the upper Pleistocene to lower Pliocene. The diatom stratigraphy indicates a disconformity at ~17.1 mbsf of 0.5- to 0.6-m.y. duration. The integration of biostratigraphic and magnetostratigraphic data identified other disconformities at ~6.0, 14.4, 15.6, and 16.0 mbsf, but the duration of these hiatuses cannot be resolved through diatom biostratigraphy. In Hole 1166A, a narrow interval of diatomaceous Quaternary sediment is identified in the upper 2.92 mbsf and dated biostratigraphically at <0.38 Ma. The remaining Quaternary-Pliocene section is dominated by diamicton, except at ~114 mbsf, where two thin diatomaceous beds are present. The lower bed is ~65 cm thick, 2.5-2.7 to 2.7-3.2 Ma in age, and possibly disconformably overlain by the upper bed, which is ~15 cm thick and 1.8-2.0 to 2.1-2.5 Ma in age. The Pliocene assemblages in Hole 1166A contain components of both Southern Ocean and Antarctic continental shelf (Ross Sea) diatom floras.