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Cyclostratigraphy and astrochronology are now at the forefront of geologic timekeeping. While this technique heavily relies on the accuracy of astronomical calculations, solar system chaos limits how far back astronomical calculations can be performed with confidence. High‐resolution paleoclimate records with Milankovitch imprints now allow reversing the traditional cyclostratigraphic approach: Middle Eocene drift sediments from Newfoundland Ridge are well‐suited for this purpose, due to high sedimentation rates and distinct lithological cycles. Per contra, the stratigraphies of Integrated Ocean Drilling Program Sites U1408–U1410 are highly complex with several hiatuses. Here, we built a two‐site composite and constructed a conservative age‐depth model to provide a reliable chronology for this rhythmic, highly resolved (<1 kyr) sedimentary archive. Astronomical components (g‐terms and precession constant) are extracted from proxy time‐series using two different techniques, producing consistent results. We find astronomical frequencies up to 4% lower than reported in astronomical solution La04. This solution, however, was smoothed over 20‐Myr intervals, and our results therefore provide constraints on g‐term variability on shorter, million‐year timescales. We also report first evidence that the g4–g3 "grand eccentricity cycle" may have had a 1.2‐Myr period around 41 Ma, contrary to its 2.4‐Myr periodicity today. Our median precession constant estimate (51.28 ± 0.56″/year) confirms earlier indicators of a relatively low rate of tidal dissipation in the Paleogene. Newfoundland Ridge drift sediments thus enable a reliable reconstruction of astronomical components at the limit of validity of current astronomical calculations, extracted from geologic data, providing a new target for the next generation of astronomical calculations. Plain Language Summary: The traditional cyclostratigraphic approach is to align and correlate a geologic depth‐series with an astronomical solution. However, the chaotic nature of the Solar System prevents astronomers from precisely calculating planetary motions beyond 40–50 million years ago. This in turn limits the options for geologists to use the resulting oscillations in Earth's climate system as a metronome for determining geologic time. In this study, we reversed the cyclostratigraphic approach and used the highly rhythmical sedimentary deposits from Newfoundland Ridge (North Atlantic) to back‐calculate planetary motions at ∼41 million years ago. The superior quality of the Newfoundland Ridge geoarchive originates from the combination of relatively high sedimentation rates (∼4 cm/kyr) and the time‐continuous character of our two‐site composite record between 39.5 and 42.8 million years ago. In this work, we had to first overcome considerable challenges in reconstructing the timing of sediment deposition, which we did with highly resolved geochemical measurements from two sites. We then were able to extract information on the Earth's planetary motion and on the Earth‐Moon interactions. These astronomical reconstructions based on geological data can now be used by astronomers to describe the evolution of the solar system further back in time than was previously possible. Key Points: A new precession‐based cyclostratigraphy for the middle Eocene intervals of IODP Sites U1408 and U1410Variability in astronomical fundamental frequencies (g‐terms) on million‐year timescales is larger than previously assumedOur precession constant estimate for 41 Ma (51.28 ± 0.56″/year) confirms earlier indicators of slower tidal dissipation in the Paleogene [ABSTRACT FROM AUTHOR]

The absolute position during the Cenozoic of northern Zealandia, a continent that lies more than 90% submerged in the southwest Pacific Ocean, is inferred from global plate motion models, because local paleomagnetic constraints are virtually absent. We present new paleolatitude constraints using paleomagnetic data from International Ocean Discovery Program Site U1507 on northern Zealandia and Site U1511 drilled in the adjacent Tasman Sea Basin. After correcting for inclination shallowing, five paleolatitude estimates provide a trajectory of northern Zealandia past position from the middle Eocene to the early Miocene, spanning geomagnetic polarity chrons C21n to C5Er (∼48–18 Ma). The paleolatitude estimates support previous works on global absolute plate motion where northern Zealandia migrated 6° northward between the early Oligocene and early Miocene, but with lower absolute paleolatitudes, particularly in the Bartonian and Priabonian (C18n–C13r). True polar wander (solid Earth rotation with respect to the spin axis), which only can be resolved using paleomagnetic data, may explain the discrepancy. This new paleomagnetic information anchors past latitudes of Zealandia to Earth's spin axis, with implications not only for global geodynamics, but also for addressing paleoceanographic and paleoclimate problems, which generally require precise paleolatitude placement of proxy data. Plain Language Summary: The ancient latitude (paleolatitude) of a tectonic plate can be determined from magnetism recorded in rocks (paleomagnetism). Earth's geomagnetic field, averaged over geological time, is symmetrical around Earth's spin axis. Hence, the direction of the remanent magnetization in rocks can provide the paleolatitude and orientation of a tectonic plate with respect to the geographic poles. Using marine sediments recovered during International Ocean Discovery Program Expedition 371, we present five paleolatitude estimates for northern Zealandia, a mostly submerged continent in the southwest Pacific encompassing New Zealand and New Caledonia. The reconstructed paleolatitudes span the time interval from 48 to 18 million years ago (middle Eocene to middle Miocene), and represent the first such estimates from northern Zealandia. Geodynamic models for Earth surface motion relative to the spin axis require several assumptions and do not accurately predict our results. Combined with data from other continents, a more precise reconstruction for Zealandia's past geography has implications for understanding various fossil records in this extensive region, including those important for past ocean circulation and climate models, and for the evolution of plants and animals. Key Points: We present five paleomagnetic‐based absolute paleolatitudes for northern Zealandia during the middle Eocene–early MiocenePaleolatitude estimates are based on paleomagnetic directions from two deep‐sea cores drilled in the Tasman SeaPrecise absolute paleolatitudes underpin accurate paleogeography, with implications for paleoclimate modeling [ABSTRACT FROM AUTHOR]

Marine plankton is an important component of the global carbon cycle. Whereas the production and seafloor export of organic carbon produced by the plankton, the biological pump, has received much attention, the long-term variability in plankton calcification, controlling the carbonate counter pump, remains less well understood. Yet, it has been shown that on geological time scales, changes in pelagic calcification (biological compensation) could affect the ocean's buffering capacity and thus regulate global carbon budget. Here we use Neogene pelagic sediments deposited on the Ceara Rise in the tropical Atlantic to characterise the variability in pelagic carbonate production with focus on warm climates. A re-evaluation of published records of carbonate accumulation at Ceara Rise reveals a systematic increase in sedimentation rates since the late Miocene, but the carbonate accumulation rate does not show a clear trend. Instead, we observe substantial orbital time-scale variability in carbonate accumulation and an effect of carbonate preservation, especially at sites located below 4 km. To evaluate long-term changes against possible orbital-scale variability, we generated new high-resolution records of carbonate accumulation rate at ODP Site 927 across two Quaternary interglacials (MIS 5 and MIS 9), the Pliocene warm period (MIS KM5) and the Miocene climate optimum (MCO). We observe that the highest carbonate accumulation rates occurred during the Pliocene but that each interval was characterised by large orbital-scale variability. Prominent variations in carbonate accumulation prior to the Quaternary preservation cycles appear to follow obliquity and eccentricity. These results imply that pelagic carbonate production in the tropical ocean, buffered from large temperature changes, varied on orbital time scales similarly or even more than on longer time scales. Since preservation can be excluded as a driver of these changes prior to the Quaternary, the observed variations must reflect changes in the export flux of pelagic biogenic carbonate. We conclude that the overall carbonate production by pelagic calcifiers responded to local changes in light, temperature and nutrients delivered by upwelling, which followed long orbital cycles, as well as to long-term shifts in climate and/or ocean chemistry. The inferred changes on both time scales were sufficiently large such that when extrapolated on a global scale, they could have played a role in the regulation of the carbon cycle and global climate evolution during the transition from the Miocene warm climates into the Quaternary icehouse. [ABSTRACT FROM AUTHOR]

Astronomical tuning of sedimentary records to precise orbital solutions has led to unprecedented resolution in the geological time scale. However, the construction of a consistent astronomical time scale for the Paleocene is controversial due to uncertainties in the recognition of the exact number of 405-kyr eccentricity cycles and accurate correlation between key records. Here, we present a new Danian integrated stratigraphic framework using the land-based Zumaia and Sopelana hemipelagic sections from the Basque Basin and deep-sea records drilled during Ocean Drilling Program (ODP) Legs 198 (Shatsky Rise, North Pacific) and 208 (Walvis Ridge, South Atlantic) that solves previous discrepancies. The new coherent stratigraphy utilises composite images from ODP cores, a new whole-rock δ 13 C isotope record at Zumaia and new magnetostratigraphic data from Sopelana. We consistently observe 11 405-kyr eccentricity cycles in all studied Danian successions. We achieve a robust correlation of bioevents and stable isotope events between all studied sections at the ∼100-kyr short-eccentricity level, a prerequisite for paleoclimatic interpretations. Comparison with and subsequent tuning of the records to the latest orbital solution La2011 provides astronomically calibrated ages of 66.022 ± 0.040 Ma and 61.607 ± 0.040 Ma for the Cretaceous–Paleogene (K–Pg) and Danian–Selandian (D–S) boundaries respectively. Low sedimentation rates appear common in all records in the mid-Danian interval, including conspicuous condensed intervals in the oceanic records that in the past have hampered the proper identification of cycles. The comprehensive interbasinal approach applied here reveals pitfalls in time scale construction, filtering techniques in particular, and indicates that some caution and scrutiny has to be applied when building orbital chronologies. Finally, the Zumaia section, already hosting the Selandian Global Boundary Stratotype Section and Point (GSSP), could serve as the global Danian unit stratotype in the future. [ABSTRACT FROM AUTHOR]

Abstract: The distinctly cyclic sediments recovered during ODP Leg 154 played an important role in constructing the astronomical time scale and associated astro(bio)chronology for the Miocene, and in deciphering ocean–climate history. The accuracy of the timescale critically depends on the reliability of the shipboard splice used for the tuning and on the tuning itself. New high-resolution colour- and magnetic susceptibility core scanning data supplemented with limited XRF-data allow improvement of the stratigraphy. The revised composite record results in an improved astronomical age model for ODP Site 926 between 5 and 14.4Ma. The new age model is confirmed by results of complex amplitude demodulation of the precession and obliquity related cycle patterns. Different values for tidal dissipation are applied to improve the fit between the sedimentary cycle patterns and the astronomical solution. Due to the improved stratigraphy and tuning, supported by the results of amplitude demodulation, the revised time scale yields more reliable age estimates for planktic foraminiferal and calcareous nannofossil events. The results of this study highlight the importance of stratigraphy for timescale construction. [Copyright &y& Elsevier]

The western equatorial Pacific is pivotal to precisely understand the global climate change and its evolution over geological time. However, continuous paleoceanographic records with high time resolution and accurate age model over the last 5 Myr are few in this important ocean region. Here, we present a high time resolution (2–3 kyr) benthic foraminiferal δ18O and δ13C record from Ocean Drilling Program Site 807 on Ontong Java Plateau in the western equatorial Pacific and establish an accurate age model for the past 5.025 Myr. Comparison of the benthic δ13C records from the west and east equatorial Pacific, and the North and South Pacific indicates that water aging effects have dominated since the Pliocene. From 4.0 Ma to 2.7 Ma, a rapid decrease in benthic δ13C gradients (Δδ13C W-E) between the west (Hole 807A) and east (ODP Site 849 and IODP Site U1338) equatorial Pacific potentially resulted from strong ventilation in the North Pacific during the warm Pliocene. The subsequent gentle decrease in benthic δ13C gradients might indicate stratification in the North Pacific and reduction of biogenic flux with the intensification of the Northern Hemisphere Glaciation (NHG) at 2.7 Ma. Both the Δδ18O W-E and Δδ13C W-E are strongly paced by 405 ka long eccentricity cycles and 41 kyr obliquity cycle, revealing the complex interplay of both high and low latitude climatic processes on deep Pacific circulation changes. • Continuous 5 Myr long high time resolution benthic foraminiferal δ18O and δ13C records in the western equatorial Pacific. • West-east equatorial Pacific δ13C gradient indicates the evolution of the Pacific deep ocean circulation over the past 5 Myr. • 405-kyr eccentricity cycle modulates the Pacific deep ocean circulation changes. [ABSTRACT FROM AUTHOR]