Astronomic calibration of the late Oligocene through early Miocene geomagnetic polarity time scale
TL;DR: In this article, the authors used the newly derived age of the Oligocene/Miocene (O/M) boundary of 23.0 Ma of Shackleton et al. (2000) 447, revised to the new astronomical calculation (La2003) of Laskar et al., to recalculate the spline ages of Cande and Kent (J. Geophys. Res. 100 (1995) 6093), and then tune the Site 1090 y 18 O record to obliquity using La2003.
About: This article is published in Earth and Planetary Science Letters.The article was published on 2004-07-30. It has received 128 citations till now. The article focuses on the topics: Polarity chron.
Citations
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01 Jan 2012
TL;DR: An Astronomically Tuned Neogene Time Scale (ATNTS2012) is presented in this article, as an update of ATNTS2004 in GTS2004, and the numerical ages are identical or almost so.
Abstract: An Astronomically Tuned Neogene Time Scale (ATNTS2012) is presented, as an update of ATNTS2004 in GTS2004. The new scale is not fundamentally different from its predecessor and the numerical ages are identical or almost so. Astronomical tuning has in principle the potential of generating a stable Neogene time scale as a function of the accuracy of the La2004 astronomical solution used for both scales. Minor problems remain in the tuning of the Lower Miocene. In GTS2012 we will summarize what has been modified or added since the publication of ATNTS2004 for incorporation in its successor, ATNTS2012. Mammal biostratigraphy and its chronology are elaborated, and the regional Neogene stages of the Paratethys and New Zealand are briefy discussed. To keep changes to ATNTS2004 transparent we maintain its subdivision into headings as much as possible.
1,479 citations
University of Bremen1, Potsdam Institute for Climate Impact Research2, University of Potsdam3, University College London4, University of Padua5, Leibniz Institute of Marine Sciences6, University of Exeter7, University of St Andrews8, National Oceanography Centre, Southampton9, National Institute of Geophysics and Volcanology10, University of Cambridge11, University of Kiel12, University of Edinburgh13, University of Bristol14, Utrecht University15, Oregon State University16, Tongji University17, University of Hawaii18, University of California, Santa Cruz19
TL;DR: A new, highly resolved, astronomically dated, continuous composite of benthic foraminifer isotope records developed in the authors' laboratories reveals the key role that polar ice volume plays in the predictability of Cenozoic climate dynamics.
Abstract: Much of our understanding of Earth's past climate comes from the measurement of oxygen and carbon isotope variations in deep-sea benthic foraminifera. Yet, long intervals in existing records lack the temporal resolution and age control needed to thoroughly categorize climate states of the Cenozoic era and to study their dynamics. Here, we present a new, highly resolved, astronomically dated, continuous composite of benthic foraminifer isotope records developed in our laboratories. Four climate states-Hothouse, Warmhouse, Coolhouse, Icehouse-are identified on the basis of their distinctive response to astronomical forcing depending on greenhouse gas concentrations and polar ice sheet volume. Statistical analysis of the nonlinear behavior encoded in our record reveals the key role that polar ice volume plays in the predictability of Cenozoic climate dynamics.
655 citations
TL;DR: A 13-million-year continuous record of Oligocene climate from the equatorial Pacific reveals a pronounced “heartbeat” in the global carbon cycle and periodicity of glaciations.
Abstract: A 13-million-year continuous record of Oligocene climate from the equatorial Pacific reveals a pronounced “heartbeat” in the global carbon cycle and periodicity of glaciations. This heartbeat consists of 405,000-, 127,000-, and 96,000-year eccentricity cycles and 1.2-million-year obliquity cycles in periodically recurring glacial and carbon cycle events. That climate system response to intricate orbital variations suggests a fundamental interaction of the carbon cycle, solar forcing, and glacial events. Box modeling shows that the interaction of the carbon cycle and solar forcing modulates deep ocean acidity as well as the production and burial of global biomass. The pronounced 405,000-year eccentricity cycle is amplified by the long residence time of carbon in the oceans.
557 citations
TL;DR: A review of recent to late Oligocene calcareous nannofossil datum events can be found in this article, where a taxonomy of the index taxa and their biostratigraphic usefulness is presented.
453 citations
01 Jan 2007
TL;DR: In this article, the authors provide a framework for the geomagnetic polarity timescale for the Late Jurassic to Recent (since 160-Ma) by using magnetostratigraphic records.
Abstract: Marine magnetic anomalies provide the framework for the geomagnetic polarity timescale for the Late Jurassic to Recent (since 160 Ma). Magnetostratigraphic records confirm that the polarity reversal sequence interpreted from magnetic anomalies is complete to a resolution of better than 30 ky. In addition to this record of polarity reversals, magnetic anomalies also appear to preserve information on geomagnetic intensity fluctuations. The correspondence of coherent near-bottom anomaly variations with independent estimates of field intensity provides strong evidence that geomagnetic intensity modulates the magnetization of the ocean crust. Indeed, many short wavelength anomaly variations in sea-surface magnetic profiles over fast-spreading ridges are likely attributable to geomagnetic intensity variations. Although longer-term geomagnetic field behavior may also be reflected in anomaly amplitudes, documenting such a signal requires a better understanding of time-dependent changes in the magnetic source (e.g., from low-temperature alteration) that may also affect magnetic anomalies.
The extrusive layer, with an average remanence of ∼ 5 A m−1, is the largest contributor to magnetic anomalies. However, enhanced sampling of oceanic gabbros (average remanence ∼ 1 A m−1) and, to a lesser extent, dikes (average remanence ∼ 2 A m−1) reveals that these deeper (and thicker) layers likely generate anomalies comparable to those from the lavas. Lava accumulation at intermediate- and fast-spreading ridges typically occurs over a narrow (1–3 km) region and dike emplacement is even more narrowly confined, resulting in a relatively high fidelity record of geomagnetic field behavior. The slow cooling of the gabbroic layer, however, results in gently dipping polarity boundaries that significantly affect the skewness of the resulting anomalies, which is also a sensitive measure of net rotations of the source layer(s). The magnetizations of the dikes and gabbros are characterized by high stability and are not expected to significantly change with time, although there are insufficient data to confirm this. The lavas, however, typically show evidence of low-temperature alteration, which has been long regarded as a process that progressively reduces the magnetization (and degrades the geomagnetic signal) in the extrusive layer and reduces the amplitude of magnetic anomalies. Sufficient data have become available to examine this conventional wisdom. There is a substantial (∼ 4x) reduction in magnetization from on-axis samples to immediately off-axis drillsites (∼ 0.5 My), but little further change in half-dozen or so deep crustal sites to ∼ 160 Ma. High paleointensity that characterizes the last few thousand years may contribute significantly to the high on-axis magnetization. The task of evaluating changes in remanence of the extrusive layer is made more difficult by substantial cooling-rate-dependent changes in magnetic properties and the systematic variation in remanence with iron content (magnetic telechemistry). The commonly cited magnetic anomaly amplitude envelope is in fact not systematically observed – the Central Anomaly is elevated at slow-spreading ridges but is not as prominent at faster spreading rates. Nonetheless, magnetic anomaly amplitudes are consistent with magnetization change is poorly constrained. Direct determinations of the degree of low-temperature oxidation reveal the presence of highly oxidized titanomagnetite in samples less than 1 My old, suggesting a short (∼ 105 years) time constant though the effects of low-temperature oxidation are quite heterogeneous. While low-temperature oxidation does have some affect on lava magnetization and anomaly amplitudes, there is increasing evidence that marine magnetic anomalies are capable of recording a broad spectrum of geomagnetic field behavior, ranging from millennial-scale paleointensity variations to polarity reversals to apparent polar wander to, more speculatively, long-term changes in average field strength. Several emerging tools and approaches – autonomous vehicles, oriented samples, absolute paleointensity of near-ridge lavas, and measurements of the vector anomalous field – are therefore likely to significantly advance our understanding of the geomagnetic signal recorded in the oceanic crust, as well as our ability to utilize this information in addressing outstanding problems in crustal accretion processes.
236 citations
Cites background from "Astronomic calibration of the late ..."
...Correlations between anomaly interpretations and magnetostratigraphy are being refined in land sections and marine cores (e.g., Billups et al., 2004; Channell et al., 2003; Lanci et al., 2004, 2005; Speranza et al., 2005) and provide the linkage to numerical ages based on radioisotopic dates or…...
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References
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Book•
01 Jan 1968
TL;DR: In this paper, Spectral Analysis and its Applications, the authors present a set of applications of spectral analysis and its application in the field of spectroscopy, including the following:
Abstract: (1970). Spectral Analysis and its Applications. Technometrics: Vol. 12, No. 1, pp. 174-175.
4,220 citations
"Astronomic calibration of the late ..." refers methods in this paper
...We estimate power spectra, coherence and phase between the orbital target and the stable isotope records using the Blackman–Tukey method [19], as implemented in AnalySeries [18], with 247 lags (f15% of the series lengths) and an effective band width of f1....
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...Spectral analyses were conducted using the AnalySeries [18] program (a), coherency (b), and yO and yC phase (c and d, respectively) estimates are based on Blackman–Tukey [19]....
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Book•
01 Jan 1982
4,055 citations
"Astronomic calibration of the late ..." refers methods in this paper
...8 Ma) used by Cande and Kent [8,9], derived from the chronogram ages for the stage boundary from Harland [27], that is the main source of error in the late Oligocene/early Miocene part of their time scale....
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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
TL;DR: A Macintosh computer program that can perform many time-series analysis procedures is now available on the Internet free of charge, originally designed for paleoclimatic time series.
Abstract: A Macintosh computer program that can perform many time-series analysis procedures is now available on the Internet free of charge. Although AnalySeries was originally designed for paleoclimatic time series, it can be useful for most fields of Earth sciences. The program's graphical user interface allows easy access even for people unfamiliar with computer calculations. Previous versions of the program are already used by hundreds of scientists worldwide.
2,015 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
"Astronomic calibration of the late ..." refers background or methods in this paper
...8 Ma for C5Bn and recalculating the spline ages of Cande and Kent [8,9]....
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...In the Cande and Kent time scale [8,9], the Oligocene/Miocene (O/M) boundary is the only GPTS calibration point between the middle Miocene (C5Bn at 14....
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...0 Ma) derived by Shackleton and others [10] but also both the relative duration of polarity chrons based on ocean magnetic anomaly data [8,9], and the middle Miocene calibration age (14....
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...(Ma) [8,9] Site 1090 tuned age (Ma) Offset: revised spline and tuned age (Ma)...
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...9 My younger than the age obtained by Cande and Kent [8,9]....
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