Miocene siliceous microfossil occurence of sediment core CRP-1 (Table 3) ...

• Main Authors: Harwood, David M, Bohaty, Steven M, Scherer, Reed P
• Format: Dataset
• Language: English
• Published: PANGAEA 1998
• Subjects: DEPTH, sediment/rock; Depth, top/min; Depth, bottom/max; Lithologic unit/sequence; Siliceous microfossils; Preservation; Arachnoidiscus sp.; Asteromphalus symmetricus; Cavitatus jouseanus; Cavitatus miocenica; Cavitatus rectus; Cymatosira biharensis; Dactyliosolen antarcticus; Fragilariopsis sp.; Diatoms indeterminata; Hercotheca inermis; Rhabdonema sp.; Rhizosolenia sp.; Stephanopyxis spinosissima; Stephanopyxis sp.; Tigeria spp.; Thalassiosira praefraga; Thalassiosira nansenii; Trinacria racovitzae; Corbisema triacantha; Septamesocena pappii; Core wireline system; Counting >25 µm fraction; Estimated; Abundance estimate; CRP-1; Sampling/drilling ice; Cape Roberts Project CRP; Antarc*; antarcticus; McMurdo Sound
• Online Access: https://dx.doi.org/10.1594/pangaea.433491; https://doi.pangaea.de/10.1594/PANGAEA.433491

Lower Miocene diatoms and other siliceous microfossils in the Cape Robcrts Project drillcore (CRP-l), Roberts Ridge, western McMurdo Sound, are documented. Diatom biostratigraphy, along with 87Sr/86Sr ratios from mollusk shells and 40Ar/39Ar data from volcanic materials, constrain the interpretation of the magnetic polarity stratigraphy and allows construction of an age model for CRP-1. Together, these records indicate an age span from to ~21.5 Ma at 147.69 mbsf (the bottom of the hole) to ~17.5 Ma at 43.15 mbsf (top of the lower Miocene interval). Important diatom datums identified in this drillcore are the FAD and LAD of Thalassiosira praefraga and the LAD of Cavitatus rectus. Variation in diatom abundance and assemblage composition through the lower Miocene reflects changes in depositional environment. There are intervals of repeated ice cover (floating or grounded) in the lower Miocene section of CRP-1, where diatom production was limited, and intervals where diatoms were growing in open, although at ... : N = none, R= rare, F = few, X = present ...