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Harwood, David M; Bohaty, Steven M; Scherer, Reed P (1998): Miocene siliceous microfossil occurence of sediment core CRP-1 (Table 3). PANGAEA,, Supplement to: Harwood, DM et al. (1998): Lower Miocene diatom biostratigraphy of the CRP-1 drillcore, McMurdo Sound, Antarctica. Terra Antartica, 5(3), 499-514, hdl:10013/epic.28337.d001

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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 * Method/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 InvestigatorMethod/DeviceComment
1DEPTH, sediment/rockDepthmGeocode
2Depth, top/minDepth topmHarwood, David M
3Depth, bottom/maxDepth botmHarwood, David M
4Lithologic unit/sequenceUnitHarwood, David M
5Siliceous microfossilsSilic foss#Harwood, David MCounting >25 µm fractionin 5 fields of view at 250x
6PreservationPreservHarwood, David MEstimated
7Arachnoidiscus sp.Arachnoidiscus sp.Harwood, David MAbundance estimatesp. A
8Asteromphalus symmetricusA. symmetricusHarwood, David MAbundance estimate
9Cavitatus jouseanusC. jouseanusHarwood, David MAbundance estimate
10Cavitatus miocenicaC. miocenicaHarwood, David MAbundance estimate
11Cavitatus rectusC. rectusHarwood, David MAbundance estimate
12Cymatosira biharensisC. biharensisHarwood, David MAbundance estimate
13Dactyliosolen antarcticusD. antarcticusHarwood, David MAbundance estimate
14Fragilariopsis sp.Fragilariopsis sp.Harwood, David MAbundance estimatesp. A
15Diatoms indeterminataDiatoms indetHarwood, David MAbundance estimate
16Hercotheca inermisH. inermisHarwood, David MAbundance estimate
17Rhabdonema sp.Rhabdonema sp.Harwood, David MAbundance estimatecf. R. elegans
18Rhizosolenia sp.Rhizosolenia sp.Harwood, David MAbundance estimatesp. B
19Stephanopyxis spinosissimaS. spinosissimaHarwood, David MAbundance estimate
20Stephanopyxis sp.Stephanopyxis sp.Harwood, David MAbundance estimatesp. C (MSSTS-1)
21Tigeria spp.Tigeria spp.Harwood, David MAbundance estimate
22Thalassiosira praefragaT. praefragaHarwood, David MAbundance estimatecomplex
23Thalassiosira nanseniiT. nanseniiHarwood, David MAbundance estimate
24Trinacria racovitzaeT. racovitzaeHarwood, David MAbundance estimate
25Corbisema triacanthaC. triacanthaHarwood, David MAbundance estimate
26Septamesocena pappiiS. pappiiHarwood, David MAbundance estimate
993 data points

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