Occurence of marine palynomorphs of sediment core CRP-1 (Table 1)

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The first core of the Cape Roberts Project, CRP-1, penetrated a Quaternary and lower Miocene section rather than the anticipated Palaeogene sediments. Initial palynologic study was conducted at the Crary Science and Engineering Laboratory, McMurdo Station, concurrent with drilling. Rapid and environmentally safe sample processing was made possible by the use of a focused microwave digestion unit that scrubbed acid fumes. In situ and/or reworked dinocysts (dinoflagellate cysts), acritarchs (leiospheres and acanthomorphs), and prasinophyte phycomata are present in the 35 samples studied. Overall, the CRP-1 assemblages are similar to Arctic marine palynomorph assemblages that are used there as ice margin indicators. Some of the acanthomorph acritarchs recovered from the CRP-1 core closely resemble cysts of extant Antarctic autotrophic sea-ice dinoflagellates. It is possible that some of these acanthomorphs are actually dinocysts, and could be used as indicators of sea-ice conditions similar to today. Most of the in situ marine palynomorphs are undescribed taxa and thus are presently of little biostratigraphic value. Dating of the core was based on diatom, palaeomagnetic and strontium isotope studies. The upper 43.55 mbsf of the core are Quaternary in age and the rest of the core, down to the bottom at 147.69 mbsf, is of early Miocene age. Although not biostratigraphically significant, the dinocysts are the first in situ Quaternary and Miocene dinocysts reported from East Antarctica, and constitute the most diverse assemblage recovered from any firmly dated Neogene section from Antarctica. In addition, they confirm that cyst-producing dinoflagellates were present in Antarctic waters during the Neogene and Quaternary. The core can be divided into three intervals based on their palynomorph assemblages (Quaternary, 0-43.55 mbsf; lower Miocene, 43.55-99.10 mbsf; and lower Miocene, 99.10- 147.69 mbsf). The distinctive palynomorph assemblages are interpreted to reflect changing climatic conditions that prevailed at the time of deposition. Overall, conditions appear to have deteriorated up-section.

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