Publication Date:
2023-06-27
Description:
Sparse low diversity early Oligocene spore-pollen assemblages above c. 410 mbsf (meters blow sea floor) in CRP-3 are dominated by Nothofagus pollen, and are very similar in composition to those from the lower part of CRP-2A. Anther-derived pollen aggregates, and a Nothofagus leaf at 44.12 mbsf show that the palynomorphs were derived from vegetation growing at the time of deposition. This woody vegetation included several species of Nothofagus and podocarpaceous conifers, a few other angiosperm families, and few cryptogams except for bryophytes, In favourable sites the vegetation may have comprised a low scrub or closed forest intermediate stature and floristic richness between that of the Eocene and the limited vegetation of the late Oligocene to earl Miocene. It may have similar to Nothofagus woodland of the present-day Magellanic region, with summer mean daily temperatures at sea level of c. 10-12° C. More stunted vegetation would have existed in exposed and upland sites. Wetland vegetation appears to have been minor, although Coptospora may in part represent a mire community.
Below c. 410 mbsf samples are mostly barren, probably due to non-deposition of fine particles and dilution by high sediment deposition. A meagre but relatively high diversity assemblage at 781.36 mbsf contains Casuarina-type pollen, unknown in the higher CRP sequence in Eocene strata of CIROS-1 and glacial erratics of the McMurdo Sound region. This limited data is consistent with Eocene dating of basal CRP-3 Cenozoic sediments from magnetostratigraphy.
Keywords:
Aggregates; Asteraceae; Campanulaceae; Cape Roberts Project; Caryophyllaceae; Chenopodipollis sp.; Cophosfora spp.; Core wireline system; Counting, palynology; CRP; CRP-3; CWS; Cyathidites minor; Cyperaceaepollis sp.; Depth, bottom/max; DEPTH, sediment/rock; Depth, top/min; Dilwynites granulatus; Fungal mycelia; Fungal spore indeterminata; Laevigatosporites spp.; Lycopodiumsporites sp.; Microcachrydites antarcticus; Myricipites harrisii; Myrtaceidites sp.; Nothofagidites asperus; Nothofagidites cf. flemingii; Nothofagidites flemingii; Nothofagidites lachlaniae; Nothofagidites spp.; Peninsulapollis cf. gillii; Podcarpidites cf. exiguus; Podcarpidites sp.; Podcarpidites spp.; Pollen, angiosperm indeterminata; Proteacidites sp.; Ranunculaceae; Ross Sea; Rugulatisporites sp.; Sampling/drilling from ice; Specimen count; Spores indeterminata; Stylidiaceae; Trichotomosulcites sp.; Trichotomosulcites subgranulatus; Tricolpites sp.; Tricolpites spp.; Tricolporites cf. Paenestriatus; Triporopollenites sp.
Type:
Dataset
Format:
text/tab-separated-values, 3868 data points
Permalink
