Data Description

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Harwood, DM et al. (1998): Miocene siliceous microfossil occurence of sediment core CRP-1 (Table 3). doi:10.1594/PANGAEA.433491,
Supplement to: Harwood, David M; Bohaty, Steven M; Scherer, Reed P (1998): Lower Miocene diatom biostratigraphy of the CRP-1 drillcore, McMurdo Sound, Antarctica. Terra Antartica, 5(3), 499-514, hdl:10013/epic.28337.d001
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 times shallow (<35 m), marine seas. Relative numbers of planktic to benthic diatoms often parallel similar indices of water depth from sedimentologic and sequencestratigraphic interpretations. Approximately 70 diatom taxa, in addition to 2 silicoflagellate and 2 ebridian taxa, are reported. No radiolarians were encountered. Three tentative diatom biostratigraphic zones are introduced, though not formally named in this report. A Ross Sea diatom zonation for the lower Miocene to upper Eocene is under development, for future publication. The forthcoming zonation will incorporate diatom biostratigraphic information from CRP-l and CRP-2, and earlier stratigraphic drilling in McMurdo Sound, as well as magnetostratigraphically calibrated datums from the Southern Ocean.
Latitude: -77.007580 * Longitude: 163.755080
Date/Time Start: 1997-10-17T01:30:00 * Date/Time End: 1997-10-24T02:00:00
Minimum DEPTH, sediment/rock: 53.550 m * Maximum DEPTH, sediment/rock: 147.685 m
CRP-1 (16 km ENE Cape Roberts) * * Latitude: -77.007580 * Longitude: 163.755080 * Date/Time Start: 1997-10-17T01:30:00 * Date/Time End: 1997-10-24T02:00:00 * Elevation: -153.5 m * Penetration: 132.06 m * Recovery: 113.32 m * Location: off Cape Roberts, Ross Sea, Antarctica * * Campaign: CRP-1 * * Basis: Sampling/drilling ice * * Device: Core wireline system (CWS) * * Comment: sea ice thickness: 1.60 m, recovery 86 %. Age and lithology of oldest strata: 22-24 Ma; mudstone with scattered pebbles.
N = none, R= rare, F = few, X = present
#NameShort NameUnitPrincipal InvestigatorMethodComment
1DEPTH, sediment/rock *DepthmGeocode
2Depth, top/min *Depth topmHarwood, David M *
3Depth, bottom/max *Depth botmHarwood, David M *
4Lithologic unit/sequence *UnitHarwood, David M *
5Siliceous microfossils *Silic foss#Harwood, David M *Counting >25 µm fraction *in 5 fields of view at 250x
6Preservation *PreservHarwood, David M *Estimated *
7Arachnoidiscus sp. *Arachnoidiscus sp.Harwood, David M *Abundance estimate *sp. A
8Asteromphalus symmetricus *A. symmetricusHarwood, David M *Abundance estimate *
9Cavitatus jouseanus *C. jouseanusHarwood, David M *Abundance estimate *
10Cavitatus miocenica *C. miocenicaHarwood, David M *Abundance estimate *
11Cavitatus rectus *C. rectusHarwood, David M *Abundance estimate *
12Cymatosira biharensis *C. biharensisHarwood, David M *Abundance estimate *
13Dactyliosolen antarcticus *D. antarcticusHarwood, David M *Abundance estimate *
14Fragilariopsis sp. *Fragilariopsis sp.Harwood, David M *Abundance estimate *sp. A
15Diatoms indeterminata *Diatoms indetHarwood, David M *Abundance estimate *
16Hercotheca inermis *H. inermisHarwood, David M *Abundance estimate *
17Rhabdonema sp. *Rhabdonema sp.Harwood, David M *Abundance estimate *cf. R. elegans
18Rhizosolenia sp. *Rhizosolenia sp.Harwood, David M *Abundance estimate *sp. B
19Stephanopyxis spinosissima *S. spinosissimaHarwood, David M *Abundance estimate *
20Stephanopyxis sp. *Stephanopyxis sp.Harwood, David M *Abundance estimate *sp. C (MSSTS-1)
21Tigeria spp. *Tigeria spp.Harwood, David M *Abundance estimate *
22Thalassiosira praefraga *T. praefragaHarwood, David M *Abundance estimate *complex
23Thalassiosira nansenii *T. nanseniiHarwood, David M *Abundance estimate *
24Trinacria racovitzae *T. racovitzaeHarwood, David M *Abundance estimate *
25Corbisema triacantha *C. triacanthaHarwood, David M *Abundance estimate *
26Septamesocena pappii *S. pappiiHarwood, David M *Abundance estimate *
993 data points

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