Early Oligocene Siliceous Microfossil Biostratigraphy of Cape Roberts Project Core CRP-3, Victoria Land Basin, Antarctica
Early Oligocene siliceous microfossils were recovered in the upper c. 193 m of the CRP-3 drillcore. Although abundance and preservation are highly variable through this section, approximately 130 siliceous microfossil taxa were identified, including diatoms, silicoflagellates, ebridians, chrysophyce...
Main Authors: | , |
---|---|
Format: | Text |
Language: | unknown |
Published: |
DigitalCommons@University of Nebraska - Lincoln
2001
|
Subjects: | |
Online Access: | https://digitalcommons.unl.edu/geosciencefacpub/193 https://digitalcommons.unl.edu/context/geosciencefacpub/article/1194/viewcontent/Harwood_TA_2001_Early_Oligocene.pdf |
id |
ftunivnebraskali:oai:digitalcommons.unl.edu:geosciencefacpub-1194 |
---|---|
record_format |
openpolar |
spelling |
ftunivnebraskali:oai:digitalcommons.unl.edu:geosciencefacpub-1194 2023-11-12T04:04:12+01:00 Early Oligocene Siliceous Microfossil Biostratigraphy of Cape Roberts Project Core CRP-3, Victoria Land Basin, Antarctica Harwood, David M. Bohaty, S. M. 2001-01-01T08:00:00Z application/pdf https://digitalcommons.unl.edu/geosciencefacpub/193 https://digitalcommons.unl.edu/context/geosciencefacpub/article/1194/viewcontent/Harwood_TA_2001_Early_Oligocene.pdf unknown DigitalCommons@University of Nebraska - Lincoln https://digitalcommons.unl.edu/geosciencefacpub/193 https://digitalcommons.unl.edu/context/geosciencefacpub/article/1194/viewcontent/Harwood_TA_2001_Early_Oligocene.pdf Papers in the Earth and Atmospheric Sciences Earth Sciences text 2001 ftunivnebraskali 2023-10-30T10:44:33Z Early Oligocene siliceous microfossils were recovered in the upper c. 193 m of the CRP-3 drillcore. Although abundance and preservation are highly variable through this section, approximately 130 siliceous microfossil taxa were identified, including diatoms, silicoflagellates, ebridians, chrysophycean cysts, and endoskeletal dinoflagellates. Well-preserved and abundant assemblages characterize samples in the upper c. 70 m and indicate deposition in a coastal setting with water depths between 50 and 200 m. Abundance fluctuations over narrow intervals in the upper c. 70 mbsf are interpreted to reflect environmental changes that were either conducive or deleterious to growth and preservation of siliceous microfossils. Only poorly-preserved (dissolved, replaced, and/or fragmented) siliceous microfossils are present from c. 70 to 193 mbsf. Diatom iostratigraphy indicates that the CRP-3 section down to c. 193 mbsf is early Oligocene in age. The lack of significant changes in composition of the siliceous microfossil assemblage suggests that no major hiatuses are present in this interval. The first occurrence (FO) of Cavitatus jouseanus at 48.44 mbsf marks the base of the Cavitatus jouseanus Zone. This datum is inferred to be near the base of Subchron C12n at c. 30.9 Ma. The FO of Rhizosolenia antarctica at 68.60 mbsf marks the base of the Rhizosolenia antarctica Zone. The FO of this taxon is correlated in deep-sea sections to Chron C13 (33.1 to 33.6 Ma). However, the lower range of R. antarctica is interpreted as incomplete in the CRP-3 drillcore, as it is truncated at an underlying interval of poor preservation; therefore, an age of c. 33.1 to 30.9 Ma is inferred for interval between c. 70 and 50 mbsf. The absence of Hemiaulus caracteristicus from diatombearing interval of CRP-3 further indicates an age younger than c. 33 Ma (Subchron C13n) for strata above c. 193 mbsf. Siliceous microfossil assemblages in CRP-3 are significantly different from the late Eocene assemblages reported CIROS-1 drillcore. The absence of H. ... Text Antarc* Antarctica Victoria Land University of Nebraska-Lincoln: DigitalCommons@UNL Victoria Land Cape Roberts ENVELOPE(-70.467,-70.467,-68.950,-68.950) |
institution |
Open Polar |
collection |
University of Nebraska-Lincoln: DigitalCommons@UNL |
op_collection_id |
ftunivnebraskali |
language |
unknown |
topic |
Earth Sciences |
spellingShingle |
Earth Sciences Harwood, David M. Bohaty, S. M. Early Oligocene Siliceous Microfossil Biostratigraphy of Cape Roberts Project Core CRP-3, Victoria Land Basin, Antarctica |
topic_facet |
Earth Sciences |
description |
Early Oligocene siliceous microfossils were recovered in the upper c. 193 m of the CRP-3 drillcore. Although abundance and preservation are highly variable through this section, approximately 130 siliceous microfossil taxa were identified, including diatoms, silicoflagellates, ebridians, chrysophycean cysts, and endoskeletal dinoflagellates. Well-preserved and abundant assemblages characterize samples in the upper c. 70 m and indicate deposition in a coastal setting with water depths between 50 and 200 m. Abundance fluctuations over narrow intervals in the upper c. 70 mbsf are interpreted to reflect environmental changes that were either conducive or deleterious to growth and preservation of siliceous microfossils. Only poorly-preserved (dissolved, replaced, and/or fragmented) siliceous microfossils are present from c. 70 to 193 mbsf. Diatom iostratigraphy indicates that the CRP-3 section down to c. 193 mbsf is early Oligocene in age. The lack of significant changes in composition of the siliceous microfossil assemblage suggests that no major hiatuses are present in this interval. The first occurrence (FO) of Cavitatus jouseanus at 48.44 mbsf marks the base of the Cavitatus jouseanus Zone. This datum is inferred to be near the base of Subchron C12n at c. 30.9 Ma. The FO of Rhizosolenia antarctica at 68.60 mbsf marks the base of the Rhizosolenia antarctica Zone. The FO of this taxon is correlated in deep-sea sections to Chron C13 (33.1 to 33.6 Ma). However, the lower range of R. antarctica is interpreted as incomplete in the CRP-3 drillcore, as it is truncated at an underlying interval of poor preservation; therefore, an age of c. 33.1 to 30.9 Ma is inferred for interval between c. 70 and 50 mbsf. The absence of Hemiaulus caracteristicus from diatombearing interval of CRP-3 further indicates an age younger than c. 33 Ma (Subchron C13n) for strata above c. 193 mbsf. Siliceous microfossil assemblages in CRP-3 are significantly different from the late Eocene assemblages reported CIROS-1 drillcore. The absence of H. ... |
format |
Text |
author |
Harwood, David M. Bohaty, S. M. |
author_facet |
Harwood, David M. Bohaty, S. M. |
author_sort |
Harwood, David M. |
title |
Early Oligocene Siliceous Microfossil Biostratigraphy of Cape Roberts Project Core CRP-3, Victoria Land Basin, Antarctica |
title_short |
Early Oligocene Siliceous Microfossil Biostratigraphy of Cape Roberts Project Core CRP-3, Victoria Land Basin, Antarctica |
title_full |
Early Oligocene Siliceous Microfossil Biostratigraphy of Cape Roberts Project Core CRP-3, Victoria Land Basin, Antarctica |
title_fullStr |
Early Oligocene Siliceous Microfossil Biostratigraphy of Cape Roberts Project Core CRP-3, Victoria Land Basin, Antarctica |
title_full_unstemmed |
Early Oligocene Siliceous Microfossil Biostratigraphy of Cape Roberts Project Core CRP-3, Victoria Land Basin, Antarctica |
title_sort |
early oligocene siliceous microfossil biostratigraphy of cape roberts project core crp-3, victoria land basin, antarctica |
publisher |
DigitalCommons@University of Nebraska - Lincoln |
publishDate |
2001 |
url |
https://digitalcommons.unl.edu/geosciencefacpub/193 https://digitalcommons.unl.edu/context/geosciencefacpub/article/1194/viewcontent/Harwood_TA_2001_Early_Oligocene.pdf |
long_lat |
ENVELOPE(-70.467,-70.467,-68.950,-68.950) |
geographic |
Victoria Land Cape Roberts |
geographic_facet |
Victoria Land Cape Roberts |
genre |
Antarc* Antarctica Victoria Land |
genre_facet |
Antarc* Antarctica Victoria Land |
op_source |
Papers in the Earth and Atmospheric Sciences |
op_relation |
https://digitalcommons.unl.edu/geosciencefacpub/193 https://digitalcommons.unl.edu/context/geosciencefacpub/article/1194/viewcontent/Harwood_TA_2001_Early_Oligocene.pdf |
_version_ |
1782341027289366528 |