Calcareous Nannofossil Biostratigraphy, Deep Sea Drilling Project Leg 85, Eastern Equatorial Pacific

Gartner, Stefan; Chow, J. M.

doi:10.2973/dsdp.proc.85.115.1985

Cited by 16 publications

(13 citation statements)

References 2 publications

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“…We monitored the range of Discoaster kugleri with an attempt to clarify the biostratigraphic value of the species, which is a wellknown "controversial" marker in the middle Miocene interval. The FO of the species, which defines the boundary CN5a/CN5b (Bukry, 1973), is considered a weak marker by many authors (e.g., Gartner and Chow, 1985;Fornaciari et al, 1990). Gartner (1992) The species, indeed, is a "sporadic, tropical species" (Bukry, 1973, p. 692), but it seemed the only criterion for dividing Zone CN5, which spans a time interval of about 3.0 m.y.…”

Section: Fo Of Calcidiscus Macintyrei (9)mentioning

confidence: 99%

Quantitative Distribution Patterns and Biomagnetostratigraphy of Middle and Late Miocene Calcareous Nannofossils from Equatorial Indian and Pacific Oceans (Legs 115, 130, and 138)

Raffi¹,

Rio²,

D'Atri³

et al. 1995

Proceedings of the Ocean Drilling Program, 138 Scientific Results

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Selected calcareous nannofossils were investigated by means of quantitative methods in middle and upper Miocene sediments from the tropical Indian Ocean (ODP Leg 115) and equatorial Pacific Ocean (DSDPLeg 85, ODP Legs 130 and 138). Our goal was to test the reliability of the classic biohorizons used in the standard zonations of Martini (1971) and Bukry (1973) and, possibly, to improve biostratigraphic resolution in the Miocene.In a time interval of about 8 m.y., from the last occurrence (LO) of S. heteromorphus ( 13.6 Ma) to the LO of D. quinqueramus ( 5.5 Ma), a total 37 events were investigated, using both the conventional and some additional markers proposed in the literature. At least 17 of these events proved to be distinct biostratigraphic correlation lines between the two considered areas. This integrated biostratigraphic framework increases the biostratigraphic resolution in the middle-upper Miocene interval (of the order of about 0.5 m.y).All the investigated events were tied to the geomagnetic polarity time scale (GPTS) and compared to biomagnetostratigraphy from mid-latitude North Atlantic Site 94-608 (Olafsson, 1991;Gartner, 1992), thus obtaining further information about the biostratigraphic and biochronologic reliability of the investigated events and a significant improvement of the available nannofossil biomagnetostratigraphic model for the middle and late Miocene.

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Section: Fo Of Calcidiscus Macintyrei (9)mentioning

confidence: 99%

Quantitative Distribution Patterns and Biomagnetostratigraphy of Middle and Late Miocene Calcareous Nannofossils from Equatorial Indian and Pacific Oceans (Legs 115, 130, and 138)

Raffi¹,

Rio²,

D'Atri³

et al. 1995

Proceedings of the Ocean Drilling Program, 138 Scientific Results

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“…This event is considered as poor by many authors (e.g. Gartner and Chow, 1985), and alternative criteria have been proposed to recognize this boundary. Bukry (1973) proposed the LO of Cyclicargolithus floridanus as a secondary marker for the base of CN5b Subzone.…”

Section: Cn5b Subzone and Nn7 Zonementioning

confidence: 99%

“…Ellis (1981) suggested as a substitute event the FO of Discoaster bollii. Gartner and Chow (1985) suggested that the LO of Coronocyclas nitescens may be useful in subdividing the interval above the LO of Sphenolithus heteromorphus and below the FO of C. coalitus.…”

Section: Cn5b Subzone and Nn7 Zonementioning

confidence: 99%

Late Oligocene through Early Pleistocene Calcareous Nannofossils from Western Equatorial Indian Ocean (Leg 115)

Rio¹,

Fornaciari²,

Raffi³

1990

Proceedings of the Ocean Drilling Program

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The chronostratigraphy, the calcareous nannofossil biochronology, and the biostratigraphy of the Miocene and Pliocene sediments retrieved during Leg 115 in the equatorial western Indian Ocean are presented and discussed. Most of the zonal boundaries of the standard 1971 zonation of Martini and the 1973 zonation of Bukry are easily recognized in these low-latitude sediments. We also comment on the secondary events that are proposed in the literature to improve the biostratigraphic resolution provided by the standard zonations.The study of calcareous nannofossil biostratigraphy and taphonomy of sequences from the Northern Mascarene Plateau area, which was drilled to investigate the Neogene history of carbonate flux and dissolution, indicate that the accumulation of carbonates in this area results from a complex interplay among carbonate bioproductivity, carbonate removal by chemical dissolution and mechanical erosion, and carbonate addition by mass and current transport. In spite of these drawbacks, major changes and trends in carbonate accumulation can be recognized, most of which, if not all, correlate with major steps in the evolution of the Neogene climatic system.

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“…This event is difficult to establish precisely because of taxonomic difficulties involving the presence of atypical specimens, most probably related to Discoaster musicus, and because of the discontinuous distribution of D. kugleri. The FO of D. kugleri is considered as a less reliable biostratigraphic indication also in previous studies (i.e., Gartner and Chow, 1985), and alternative criteria have been proposed to subdivide the CN5 (NN6/NN7) zonal interval: the LO of Cyclicargolithus floridanus (Bukry, 1973), the FO of Discoaster bollii (Ellis, 1981), and the LO of Coronocyclus nitescens (Gartner and Chow, 1985). Of these three events, the LO of C. floridanus is discussed above.…”

Section: The Subdivision Of Middle Miocene Zone Cn5mentioning

confidence: 99%

Quantitative Distribution Patterns of Oligocene and Miocene Calcareous Nannofossils from the Western Equatorial Indian Ocean

Fornaciari¹,

Raffi²,

Rio³

et al. 1990

Proceedings of the Ocean Drilling Program, 115 Scientific Results

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Biostratigraphically useful nannofossil markers were investigated by means of quantitative methods in Oligocene through middle Miocene sediments from the western tropical Indian Ocean. In the Oligocene a distinct shift in dominance between Sphenolithus predistentus and Sphenolithus distentus represents a better marker event than the first occurrence (FO) of the latter for recognition of the CP17/CP18 boundary. Similarly, the shift in dominance between S. distentus and Sphenolithus ciperoensis at 28.8 Ma provides a more reliable indication for the CP19a/CP19b (NP24/ NP25) boundary than the last occurrence (LO) of the former species, which may occur as late as 27.4 Ma. Because it is rare in the critical interval and occurs well within the early Miocene, the LO of Helicosphaera recta (NP25/NN1 boundary) provides unreliable biostratigraphic informationIn the Miocene, an acme interval of Sphenolithus delphix that ranges in age from 23.6 to 24.7 Ma, is an important addition to the poorly resolved biostratigraphy of the early Miocene. The midpoint of this short acme interval of S. delphix would form a suitable criterion for replacing the formal CNla/CNlb boundary definition (end acme Cyclicargolithus abisectus), which has never been defined quantitatively.No overlap in the ranges of Sphenolithus belemnos and Sphenolithus heteromorphus was observed. The LO of Coronocyclus nitescens provides a more reliable biostratigraphic signal than the FO of Discoaster kugleri for subdivision of the CN5 (NN6-NN7) interval. Biometric analysis of Calcidiscus placolith size revealed a clear bimodal distribution into forms larger or smaller than 10 ^m, in sediments of late Pliocene-early Pleistocene age. The middle Miocene populations, however, are clearly unimodal. Morphotypes > 11 ^m appear rather distinctly in Subzone CN5b between about 11 and 12 Ma.

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Calcareous Nannofossil Biostratigraphy, Deep Sea Drilling Project Leg 85, Eastern Equatorial Pacific

Cited by 16 publications

References 2 publications

Quantitative Distribution Patterns and Biomagnetostratigraphy of Middle and Late Miocene Calcareous Nannofossils from Equatorial Indian and Pacific Oceans (Legs 115, 130, and 138)

Quantitative Distribution Patterns and Biomagnetostratigraphy of Middle and Late Miocene Calcareous Nannofossils from Equatorial Indian and Pacific Oceans (Legs 115, 130, and 138)

Late Oligocene through Early Pleistocene Calcareous Nannofossils from Western Equatorial Indian Ocean (Leg 115)

Quantitative Distribution Patterns of Oligocene and Miocene Calcareous Nannofossils from the Western Equatorial Indian Ocean

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