Integrated chronostratigraphic calibration of the Oligocene-Miocene boundary at 24.0 ± 0.1 Ma from the CRP-2A drill core, Ross Sea, Antarctica
University of Otago1, University of Cambridge2, New Mexico Institute of Mining and Technology3, University of Southampton4, University of Nebraska–Lincoln5, University of Parma6, University of California, Santa Cruz7, University of Queensland8, National Institute of Geophysics and Volcanology9, GNS Science10, Northern Illinois University11, University of California, Davis12
TL;DR: In this paper, an expanded Oligocene-Miocene boundary interval recovered in the Cape Roberts Project CRP-2A core from beneath the Ross Sea, Antarctica, has yielded a high-resolution integrated chrono stratigraphy that has, in turn, enabled a new, more direct, calibra tion of magnetic polarity and biostratigraphic events.
Abstract: An expanded Oligocene-Miocene boundary interval recovered in the Cape Roberts Project CRP-2A core from beneath the Ross Sea, Antarctica, has yielded a high-resolution integrated chrono stratigraphy that has, in turn, enabled a new, more direct, calibra tion of magnetic polarity and biostratigraphic events. The Oligocene-Miocene boundary interval in the CRP-2A core comprises three ∼60-m-thick, rapidly deposited (>0.5 m/k.y.) sedimentary sequences (sequences 9, 10, and 11). In sequences 10 and 11, single-crystal, laser-fusion 40Ar/39Ar analyses of anorthoclase phenocrysts from two tephra horizons independently calibrate the CRP-2A magnetic-polarity stratigraphy and age model. Sequences 10 and 11 encompass subchron C6Cn.3n, which is dated as 24.3 ± 0.1 to 24.16 ± 0.1 Ma. Sequence 9 is interpreted to encompass subchron C6Cn.2n and the Oligocene-Miocene boundary, which is dated as 24.0 ± 0.1 Ma. These ages are ∼0.2 m.y. older than those of the geomagnetic polarity time scale calibrated from seafloor-spreading ridges and ∼0.9–1.3 m.y. older than the newly proposed astronomically calibrated ages. We contend that the discrepancy with the astronomically calibrated ages arises from a mismatch of three 406 k.y. eccentricity cycles or a 1.2 m.y. modulation of obliquity amplitude in the astronomical calibration of the Oligocene–Miocene time scale.
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19 Mar 2013
TL;DR: In this paper, the Eocene and Oligocene diatom floras are illustrated in nine figures and the ages for the intervals of these cores are determined based on diatom biostratigraphy with additional constraints from calcareous nannofossil and dinoflagellate cyst biostraigy and strontium isotope dating.
Abstract: Tecton Specia Copyr 10.102 Pre-Quaternary strata were recovered from four sites on the continental shelf of the eastern Antarctic Peninsula during the SHALDRIL II cruise, NBP0602A (March–April 2006). Fully marine shelf sediments characterize these short cores and contain a mixture of opaline, carbonate-walled, and organic-walled microfossils, suitable for both biostratigraphic and paleoenvironmental studies. Here we compile biostratigraphic information and provide age assessments for the Eocene–Pliocene intervals of these cores, based primarily on diatom biostratigraphy with additional constraints from calcareous nannofossil and dinoflagellate cyst biostratigraphy and strontium isotope dating. The Eocene and Oligocene diatom floras are illustrated in nine figures. A late Eocene age (~37–34 Ma) is assigned to strata recovered in Hole 3C, and a late Oligocene age (~28.4–23.3 Ma) is determined for strata recovered in Hole 12A. Middle Miocene (~12.8–11.7 Ma) and early Pliocene (~5.1–4.3 Ma) ages are assigned to the sequence recovered in holes 5C and 5D, and an early Pliocene age (~5.1–3.8 Ma) is interpreted for cores recovered in holes 6C and 6D. These ages provide chronostratigraphic ground truthing for the thick sequences of Paleogene and Neogene strata present on the northwestern edge of the James Ross Basin and on the northeastern side of the Joinville Plateau, as interpreted from a network of seismic stratigraphic survey lines in the drilling areas. Although representing a coarse-resolution sampling of the complete sedimentary package, the well-constrained ages for these cores also
19 citations
Dissertation•
04 Dec 2008
TL;DR: In this article, the authors present a compilation of 56 nouveaux âges K-Ar from the Petites Antilles of the Martinique island, with dates between 26 and 190 ka.
Abstract: Nous presentons ici un travail qui combine des etudes de geochronologie, geochimie et geomorphologie sur l'ile de la Martinique afin de contraindre l'evolution de l'activite volcanique de l'ile. L'arc insulaire des Petites Antilles, double dans sa moitie nord, resulte de la subduction vers l'ouest de la plaque Atlantique sous la plaque Caraibe a 2 cm/an. Grâce a sa position centrale ou les deux branches nord se rejoignent, la Martinique est la seule ile des Petites Antilles ou l'histoire la plus complete de l'arc affleure. Nos âges K-Ar montrent que l'Arc Ancien a ete actif de 25 a 21 Ma. L'Arc Intermediaire s'est ensuite mis en place en milieu sous-marin puis subaerien entre 16 et 7 Ma. Au cours du Miocene, l'activite volcanique s'est deplacee vers l'ouest avec la mise en place de petits volcans monogeniques, alignes le long de failles, entre 3 Ma et 340 ka. Au meme moment, le compartiment septentrional s'est edifie au niveau du volcan bouclier du Morne Jacob (5.5 – 1.5 Ma), du Complexe du Carbet (1 Ma – 322 ka), du Mont Conil (550 – 190 ka) et enfin de la Montagne Pelee. Nous avons mis en evidence l'etroite relation de l'evolution chimique des laves et des taux d'eruption avec les modifications de surface, ainsi que l'influence de la subduction de rides asismiques sur la migration et la repartition de l'activite volcanique a travers et le long de l'arc. En conclusion, notre compilation de 56 nouveaux âges K-Ar entre 26 Ma et 190 ka, nous permet de mieux contraindre les differentes phases volcaniques de l'ile de la Martinique, et d'identifier des episodes de forte production magmatique lies aux changements geodynamiques regionaux et/ou les evenements d'effondrement de flanc.
19 citations
Cites background or methods from "Integrated chronostratigraphic cali..."
...(2000) could arise from eccentricity cycles mismatch as previously proposed (Wilson et al. 2002), and/or to the challenge of retrieving high resolution calibration in such a relatively low sedimentation rate environment....
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...Although, it is older than the age of 23.03 Ma used in the last geologic time scale, it is compatible with the age of 24.0 ± 0.1 Ma (Wilson et al. 2002) derived from 40Ar/39Ar dating of tephra from Antarctica (McIntosh 2000)....
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...1 Ma (Wilson et al. 2002), although with a more reasonable uncertainty of 1% (i....
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...1 Ma (Wilson et al. 2002) derived from (40)Ar/(39)Ar dating of tephra from Antarctica (McIntosh 2000)....
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TL;DR: In this paper, the authors investigated the evolution of The Pleiades, a Quaternary alkalic volcanic complex in Northern Victoria Land (NVL), Antarctica, using major and trace element, and Sr, Nd and Pb isotopic data.
Abstract: The magmatic evolution of The Pleiades, a Quaternary alkalic volcanic complex in Northern Victoria Land (NVL), Antarctica, is investigated using major and trace element, and Sr, Nd and Pb isotopic data. The volcanic rocks can be subdivided into two distinct magmatic lineages based on petrography and whole-rock compositions: (1) a sodic silica-undersaturated lineage with abundant kaersutite phenocrysts and (2) a potassic and mildly-alkalic, silica-saturated to slightly undersaturated lineage containing olivine phenocrysts but no kaersutite. The pressure–temperature paths estimated by clinopyroxene–liquid thermobarometry are similar in each lineage. Massbalance calculations using whole-rock and mineral compositions show that kaersutite fractionation without olivine has played a major role in magmatic differentiation of the sodic lineage, whereas the compositional variations of the potassic lineage can be ascribed to fractionation of an assemblage of plagioclase, clinopyroxene, olivine, titanomagnetite and apatite, combined with about 10% lower crustal assimilation. The higher Sr/Sr (> 0 7035), lower Nd/Nd (< 0 51285), and Pb/Pb (< 19 3) ratios of the evolved potassic lavas compared to the mafic lavas support crustal assimilation. The mafic lavas from both lineages are characterized by elevated Pb/Pb (>19 5) ratios and narrow ranges of Sr/Sr (0 70313–0 70327) and Nd/Nd (0 51289–0 51290) ratios, which is consistent with a high m-like (HIMU, where m1⁄4(U/Pb)t1⁄40) component typical of Cenozoic volcanic rocks in Antarctica and Zealandia. This HIMU-like isotopic signature of The Pleiades volcanic rocks, together with elevated Nb concentrations and negative K anomalies in primitive mantle-normalized diagrams, suggests an amphibole-bearing metasomatized lithospheric mantle source. We suggest that the primary magmas of the two lineages were formed by partial melting of metasomatic hydrous veins in the lithospheric mantle with varying degrees of reaction with the surrounding, anhydrous peridotite. The drier potassic magma experienced greater peridotite assimilation relative to the more hydrous sodic magmas. This hypothesis is supported by lower contents of Al2O3, TiO2, K2O, Rb, and Nb in the mafic potassic lavas compared to the sodic ones. This initial difference was intensified by crustal assimilation in the potassic magma suite, resulting in a silica-saturated alkalic trend which is distinct from the trend of the sodic silica-undersaturated alkalic magmas. VC The Author(s) 2018. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com 117 J O U R N A L O F P E T R O L O G Y Journal of Petrology, 2019, Vol. 60, No. 1, 117–150 doi: 10.1093/petrology/egy108 Advance Access Publication Date: 5 December 2018
17 citations
Cites background from "Integrated chronostratigraphic cali..."
...They are part of the extensive Cenozoic McMurdo Volcanic Group (Kyle, 1990b; Wilson et al., 2002) in the western Ross Sea....
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TL;DR: Barrett et al. as discussed by the authors presented an updated biostratigraphy and zonation scheme based on the latest taxonomic concepts and on new quantitative and qualitative siliceous microfossil data from the Cape Roberts Project Core CRP-2/2A, Victoria Land Basin, Antarctica.
Abstract: Lower Oligocene (ca. 31 Ma) to lower Miocene (ca. 18.5 Ma) biosiliceous microfossils recovered from the Cape Roberts Project (CRP-2/2A) drill cores provide both paleoenvironmental and biostratigraphic information, enhancing our understanding of the geological history of the Victoria Land Basin, Antarctica. The biochronostratigraphic record obtained provides key data with which time–space–facies models may be developed. Assemblages of neritic and pelagic microfossils such as those from the CRP-2/2A drill cores provide links between the primarily pelagic microfossil-derived chronostratigraphy of the Southern Ocean and the facies models of the neritic zone.
The CRP-2/2A holes drilled in the Victoria Land Basin, Antarctica during 1998 [Barrett, P.J., et al. (Eds.), 2001. Studies from the Cape Roberts Project, Ross Sea, Antarctica, Scientific Results of CRP-2/2A, Parts I and II: Terra Antartica, vol. 7(4/5), 665pp] include several sections that contain well-preserved and relatively abundant biosiliceous microfossils. Scherer et al. [2001. Oligocene and Lower Miocene Siliceous Microfossil Biostratigraphy of Cape Roberts Project Core CRP-2/2A, Victoria Land Basin, Antarctica. In: Barrett, P.J., Ricci, C.A. (Eds.) Studies from the Cape Roberts Project, Ross Sea, Antarctica, Scientific Report of CRP-2/2A, Terra Antartica, vol. 7(4), pp. 417–442] produced a biostratigraphic zonal framework consisting of 10 biozones; two of the zonal boundaries were correlated with the magnetostratigraphically calibrated Southern Ocean diatom biozonation. Many of the taxa observed and utilized in the above framework could not be assigned categorically to existing taxa, leading to use of informal nomenclature. We present an updated biostratigraphy and zonation scheme based on the latest taxonomic concepts and on new quantitative and qualitative siliceous microfossil data from the CRP-2/2A drill core, including formal description of four new diatom taxa used in the definition of Antarctic nearshore diatom zonal boundaries. New taxa formally proposed are Fragilariopsis truncata, Cymatosira palpebraforma, Rhizosolenia fidicularis, and Hemiaulus angustobrachiatus.
16 citations
TL;DR: In this paper, a number of undescribed species were reported, most strikingly of the distinctive dinoflagellate cyst genus Lejeunecysta, and a new zonation comprising five marine palynomorph biozones is proposed, largely based upon the new taxa.
14 citations
References
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TL;DR: An adjusted geomagnetic reversal chronology for the Late Cretaceous and Cenozoic is presented that is consistent with astrochronology in the Pleistocene and Pliocene and with a new timescale for the Mesozoic.
Abstract: Recently reported radioisotopic dates and magnetic anomaly spacings have made it evident that modification is required for the age calibrations for the geomagnetic polarity timescale of Cande and Kent (1992) at the Cretaceous/Paleogene boundary and in the Pliocene. An adjusted geomagnetic reversal chronology for the Late Cretaceous and Cenozoic is presented that is consistent with astrochronology in the Pleistocene and Pliocene and with a new timescale for the Mesozoic. The age of 66 Ma for the Cretaceous/Paleogene (K/P) boundary used for calibration in the geomagnetic polarity timescale of Cande and Kent (1992) (hereinafter referred to as CK92) was supported by high precision laser fusion Ar/Ar sanidine single crystal dates from nonmarine strata in Montana. However, these age determinations are now
3,582 citations
"Integrated chronostratigraphic cali..." refers background or methods in this paper
...…that the geomagnetic polarity time scale in the vicinity of the Oligocene-Miocene boundary was ;0.2 m.y. older than the conventional calibration of the geomagnetic polarity time scale (Cande and Kent, 1995) and 0.9–1.3 m.y. older than the astronomical calibration of Shackleton et al. (2000)....
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...We conclude that it is not possible to resolve *E-mail: Channell—jetc@ufl.edu; Martin—emartin@geology.ufl.edu. ages in the 23.5 to 25 Ma (C7–C6C) interval of the CK95 time scale (Cande and Kent, 1995) using strontium isotopes....
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...Ages are reported with respect to the time scale of Cande and Kent (1995)....
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01 Jan 1995
TL;DR: Cande and Kent as mentioned in this paper presented a revised (integrated magnetobiochronologic) Cenozoic time scale (IMBTS) based on an assessment and integration of data from several sources.
Abstract: Since the publication of our previous time scale (Berggren and others, 1985c = BKFV85) a large amount of new magneto- and biostratigraphic data and radioisotopic ages have become available. An evaluation of some of the key magnetobiostratigraphic calibration points used in BKFV85, as suggested by high precision 40 Ar/ 39 Ar dating (e.g., Montanari and others, 1988; Swisher and Prothero, 1990; Prothero and Swisher, 1992; Prothero, 1994), has served as a catalyst for us in developing a revised Cenozoic time scale. For the Neogene Period, astrochron- ologic data (Shackleton and others, 1990; Hilgen, 1991) required re-evaluation of the calibration of the Pliocene and Pleistocene Epochs. The significantly older ages for the Pliocene-Pleistocene Epochs predicted by astronomical calibrations were soon corroborated by high precision 40 Ar/ 39 Ar dating (e.g., Baksi and others, 1992; McDougall and others, 1992; Tauxe and others, 1992; Walter and others, 1991; Renne and others, 1993). At the same time, a new and improved definition of the Late Cretaceous and Cenozoic polarity sequence was achieved based on a comprehensive evaluation of global sea-floor magnetic anomaly profiles (Cande and Kent, 1992). This, in turn, led to a revised Cenozoic geomagnetic polarity time scale (GPTS) based on standardization to a model of South Atlantic spreading history (Cande and Kent, 1992/1995 = CK92/95). This paper presents a revised (integrated magnetobiochronologic) Cenozoic time scale (IMBTS) based on an assessment and integration of data from several sources. Biostratigraphic events are correlated to the recently revised global polarity time scale (CK95). The construction of the new GPTS is outlined with emphasis on methodology and newly developed polarity history nomenclature. The radioisotopic calibration points (as well as other relevant data) used to constrain the GPTS are reviewed in their (bio)stratigraphic context. An updated magnetobiostratigraphic (re)assessment of about 150 pre-Pliocene planktonic foraminiferal datum events (including recently avail- able high southern (austral) latitude data) and a new/modified zonal biostratigraphy provides an essentially global biostratigraphic correlation framework. This is complemented by a (re)assessment of nearly 100 calcareous nannofossil datum events. Unrecognized unconformities in the stratigraphic record (and to a lesser extent differences in taxonomic concepts), rather than latitudinal diachrony, is shown to account for discrep- ancies in magnetobiostratigraphic correlations in many instances, particularly in the Paleogene Period. Claims of diachrony of low amplitude (<2 my) are poorly substantiated, at least in the Paleocene and Eocene Epochs. Finally, we (re)assess the current status of Cenozoic chronostratigraphy and present estimates of the chronology of lower (stage) and higher (system) level units. Although the numerical values of chronostratigraphic units (and their boundaries) have changed in the decade since the previous version of the Cenozoic time scale, the relative duration of these units has remained essentially the same. This is particularly true of the Paleogene Period, where the Paleocene/Eocene and Eocene/Oligocene boundaries have been shifted ~2 my younger and the Cretaceous/Paleogene boundary ~1 my younger. Changes in the Neogene time scale are relatively minor and reflect primarily improved magnetobiostratigraphic calibrations, better understanding of chronostratigraphic and magnetobiostratigraphic relationships, and the introduction of a congruent astronom- ical/paleomagnetic chronology for the past 6 my (and concomitant adjustments to magnetochron age estimates).
3,122 citations
TL;DR: In this paper, the fitting of a straight line when both variables are subject to crrors is generalized to allow for correlation of the z and y errors, illustrated by reference to lead isochron fitting.
2,237 citations
TL;DR: In this article, the relative widths of the magnetic polarity intervals for the entire Late Cretaceous and Cenozoic have been systematically determined from magnetic profiles from the world's ocean basins.
Abstract: We have constructed a magnetic polarity time scale for the Late Cretaceous and Cenozoic based on an analysis of marine magnetic profiles from the world's ocean basins. This is the first time, since Heirtzler et al. (1968) published their time scale, that the relative widths of the magnetic polarity intervals for the entire Late Cretaceous and Cenozoic have been systematically determined from magnetic profiles. A composite geomagnetic polarity sequence was derived based primarily on data from the South Atlantic. Anomaly spacings in the South Atlantic were constrained by a combination of finite rotation poles and averages of stacked profiles. Fine-scale information was derived from magnetic profiles on faster spreading ridges in the Pacific and Indian Oceans and inserted into the South Ariantic sequence. Based on the assumption that spreading rates in the South Atlantic were smoothly varying but not necessarily constant, a time scale was generated by using a spline function to fit a set of nine age calibration points
1,408 citations
"Integrated chronostratigraphic cali..." refers background or methods in this paper
...…that the geomagnetic polarity time scale in the vicinity of the Oligocene-Miocene boundary was ;0.2 m.y. older than the conventional calibration of the geomagnetic polarity time scale (Cande and Kent, 1995) and 0.9–1.3 m.y. older than the astronomical calibration of Shackleton et al. (2000)....
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...We conclude that it is not possible to resolve *E-mail: Channell—jetc@ufl.edu; Martin—emartin@geology.ufl.edu. ages in the 23.5 to 25 Ma (C7–C6C) interval of the CK95 time scale (Cande and Kent, 1995) using strontium isotopes....
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...Ages are reported with respect to the time scale of Cande and Kent (1995)....
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TL;DR: An improved and updated version of the statistical LOWESS fit to the marine 87Sr/86Sr record and a revised look-up table (V3:10/99; available from jmcarthur@ucl.ac.uk) is presented in this article.
Abstract: An improved and updated version of the statistical LOWESS fit to the marine 87Sr/86Sr record and a revised look-up table (V3:10/99; available from j.mcarthur@ucl.ac.uk) based upon it enables straightforward conversion of 87Sr/86Sr to numerical age, and vice versa, for use in strontium isotope stratigraphy (SIS). The table includes 95% confidence intervals on predictions of numerical age from 87Sr/86Sr. This version includes the Triassic and Paleozoic record (0509 Ma) omitted from previous versions because of the paucity of adequate data at the time of preparation. We highlight differences between the previous versions of the table and the current version and discuss some aspects of the 87Sr/86Sr record that may have geological significance. We give examples of how the table can be used and where it has proven useful.
1,303 citations
"Integrated chronostratigraphic cali..." refers background in this paper
...* 87Sr/86Sr age errors include the 2s measurement error, a 2s long-term laboratory error for standard determination (NIST-987 5 0.710249) and error in the LOWESS fit to the marine Sr curve of McArthur et al. (2001)....
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...The 87Sr/86Sr ages given for core CRP-2A (Lavelle, 2000; Wilson et al., 2002) are based on the 87Sr/86Sr age tables of McArthur et al. (2001)....
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