Description: A high-resolution stratigraphy is essential toward deciphering climate variability in detail and understanding causality arguments of events in earth history. Because the highly dynamic middle to late Eocene provides a suitable testing ground for carbon cycle models for a waning warm world, an accurate time scale is needed to decode climate-driving mechanisms. Here we present new results from ODP Site 1260 (Leg 207) which covers a unique expanded middle Eocene section (magnetochrons C18r to C20r, late Lutetian to early Bartonian) of the tropical western Atlantic including the chron C19r transient hyperthermal event and the Middle Eocene Climate Optimum (MECO). To establish a detailed cyclostratigraphy we acquired a distinctive iron intensity records by XRF scanning Site 1260 cores. We revise the shipboard composite section, establish a cyclostratigraphy and use the exceptional eccentricity modulated precession cycles for orbital tuning. The new astrochronology revises the age of magnetic polarity chrons C19n to C20n, validates the position of very long eccentricity minima at 40.2 and 43.0 Ma in the orbital solutions, and extends the Astronomically Tuned Geological Time Scale back to 44 Ma. For the first time the new data provide clear evidence for an orbital pacing of the chron C19r event and a likely involvement of the very long eccentricity cycle contributing to the evolution of the MECO.

Description: To explore cause and consequences of past climate change, very accurate age models such as those provided by the astronomical timescale (ATS) are needed. Beyond 40 million years the accuracy of the ATS critically depends on the correctness of orbital models and radioisotopic dating techniques. Discrepancies in the age dating of sedimentary successions and the lack of suitable records spanning the middle Eocene have prevented development of a continuous astronomically calibrated geological timescale for the entire Cenozoic Era. We now solve this problem by constructing an independent astrochronological stratigraphy based on Earth's stable 405 kyr eccentricity cycle between 41 and 48 million years ago (Ma) with new data from deep-sea sedimentary sequences in the South Atlantic Ocean. This new link completes the Paleogene astronomical timescale and confirms the intercalibration of radioisotopic and astronomical dating methods back through the Paleocene-Eocene Thermal Maximum (PETM, 55.930 Ma) and the Cretaceous-Paleogene boundary (66.022 Ma). Coupling of the Paleogene 405 kyr cyclostratigraphic frameworks across the middle Eocene further paves the way for extending the ATS into the Mesozoic.

Description: A consistent chronostratigraphic framework is required to understand the effect of major paleoclimate perturbations on both marine and terrestrial ecosystems. Transient global warming events in the early Eocene, 56-54 Ma ago, show the impact of large scale carbon input into the ocean-atmosphere system. Here we provide the first time-scale synchronization of continental and marine deposits spanning the Paleocene-Eocene Thermal Maximum (PETM) and the interval just prior to the Eocene Thermal Maximum 2 (ETM-2). Cyclic variations in geochemical data come from continental drill cores of the Bighorn Basin Coring Project (BBCP, Wyoming, USA) and from marine deep-sea drilling deposits retrieved by the Ocean Drilling Program (ODP). Both are dominated by eccentricity modulated precession cycles used to construct a common cyclostratigraphic framework. Integration of age models results in a revised astrochronology for the PETM in deep-sea records that is now generally consistent with independent 3He age models. The duration of the PETM is estimated at ~200 kyr for the CIE and ~120 kyr for the associated pelagic clay layer. A common terrestrial and marine age model shows a concurrent major change in marine and terrestrial biotas ~200 kyr before ETM-2. In the Bighorn Basin, the change is referred to as Biohorizon B, and represents a period of significant mammalian turnover and immigration, separating the upper Haplomylus-Ectocion Range Zone from the Bunophorus Interval Zone and approximating the Wa-4-Wa-5 land mammal zone boundary. In sediments from ODP Site 1262 (Walvis Ridge), major changes in the biota at this time are documented by the radiation of a "2nd generation" of apical spine-bearing sphenoliths species (e.g., S. radians and S. editus), the emergence of T. orthostylus, and the marked decline of D. multiradiatus.

Description: These files contain individual core images generated from core box photos using the Code for Ocean Drilling Data (CODD) software set. There are PNG images with mcd depth scales attached for use in graphics programs as well as scaled Igor binary images for use with CODD. MCD depths are from the offsets.

Description: Ocean Drilling Programme (ODP) Site 982 represents a key location for understanding the evolution of climate in the North Atlantic over the past 12 Ma. However, concerns exist about the validity and robustness of the underlying stratigraphy and astrochronology, which currently limits the adequacy of this site for high-resolution climate studies. To resolve this uncertainty, we verify and extend the early Pliocene to late Miocene shipboard composite splice at Site 982 using high-resolution XRF core scanning data and establish a robust high-resolution stable isotope stratigraphy and astrochronology between 4.5 and 8.0 Ma. Splice revisions and verifications resulted in ~11 m of gaps in the original Site 982 isotope stratigraphy. Our new stratigraphy reveals previously unseen benthic d18O excursions, particularly prior to 6.65 Ma. The benthic d18O record displays distinct, asymmetric cycles between 7.7 and 6.65 Ma, confirming that high-latitude climate is a prevalent forcing during this interval. An intensification of the 41-kyr beat in both the benthic d13C and d18O is also observed ~6.4 Ma, marking a strengthening in the cryosphere-carbon cycle coupling. A large ~0.7 per mil double excursion is revealed ~6.4-6.3 Ma, which also marks the onset an interval of average higher d18O and large precession and obliquity-dominated d18O excursions between 6.4-5.4 Ma, coincident with the culmination of the late Miocene cooling. The two largest benthic d18O excursions ~6.4-6.3 Ma and TG20/22 coincide with the coolest alkenone-derived SST estimates from Site 982, suggesting a strong connection between the late Miocene global cooling and deep-sea cooling and dynamic ice sheet expansion. The splice revisions and revised astrochronology resolve key stratigraphic issues that have hampered correlation between Site 982, the equatorial Atlantic and the Mediterranean. Comparisons of the revised Site 982 stratigraphy to high-resolution astronomically tuned benthic d18O stratigraphies from ODP Site 926 (equatorial Atlantic) and Ain el Beida (north western Morocco) show that prior inconsistencies in short-term excursions are now resolved. The identification of key new cycles at Site 982 further highlights the requirement for the current scheme for late Miocene marine isotope stages to be redefined. Our new integrated deep-sea benthic stable isotope stratigraphy and astrochronology from Site 982 will facilitate future high-resolution late Miocene to early Pliocene climate research.

Description: The Late Cretaceous-Early Paleogene is the most recent period of Earth history that experienced sustained global greenhouse warmth and was characterised by a dynamic carbon cycle. Yet, knowledge of ambient climate conditions and the evolution of atmospheric pCO2 at this time, along with their relation to forcing mechanisms, are still poorly constrained. Here we present an unprecedented 14.75 million year long high-resolution orbitally-tuned record of paired climate change and carbon-cycling (based on the oxygen and carbon isotope composition of benthic foraminiferal tests) compiled to date for the enigmatic Late Cretaceous to Early Eocene, and compare these records to the most up-to-date compilation of atmospheric pCO2 records for this time. We identify eccentricity as the dominant pacemaker of the observed climate and carbon cycle changes, through the modulation of precession. The carbon cycle (e.g., d13C) lagged changes in climate by ~22,800 years within the long eccentricity (405,000 year) band and ~3,000-4,500 years within the short eccentricity (100,000 year) band, suggesting that light carbon was released as a positive feedback to warming induced by small changes in orbital forcing. The majority of the hyperthermals of this time period occur during maxima in the long eccentricity cycle, with the exception of the Paleocene-Eocene Thermal Maximum and Late Maastrichtian warming event, which are likely to have been triggered by Large Igneous Province volcanism.

Description: It contains three tables that correspond to the supplementary information of the article mentioned above. Tables S3 and S4 can be found within the Supplementary Information document. Table S1 contains high-resolution bulk and benthic carbon and oxygen stable isotope data from ODP Hole 702B across the Middle Eocene Climatic Optimum (40 Ma). Table S2 contains benthic foraminiferal data (relative abundance and ecology index) and accumulation rates from ODP Hole 702B across the Middle Eocene Climatic Optimum (40 Ma). Table S5 contains middle Eocene ODP Hole 702B XRF core scanning data, high-resolution bulk and benthic carbon and oxygen stable isotope data from ODP Site 1263 and age model correlation tie points between drill sites for ODP Sites 1263, 738 and 702B as well tie points for a detailed astronomical age model for ODP Site 1263 (La2010b solution).

Description: We refined the strontium isotope seawater curve for the Paleocene and early Eocene by analysis of samples recovered from the Walvis Ridge during Ocean Drilling Project (ODP) Leg 208. The highest 87Sr/86Sr values occurred in the earliest Paleocene at 65 Ma and generally decreased throughout the Paleocene, reaching minimum values between 53 and 51 Ma in the early Eocene before beginning to increase again at 50 Ma. A plausible explanation for the 87Sr/86Sr decrease between 65 and 51 Ma is increased rates of hydrothermal activity and/or the eruption and weathering of large igneous provinces (e.g., Deccan Traps and North Atlantic). Strontium isotope variations closely parallel sea level and benthic d18O changes during the late Paleocene and early Eocene, supporting previous studies linking tectonic reorganization and increased volcanism to high sea level, high CO2, and warm global temperatures.

Description: The Late Paleocene and Early Eocene were characterised by warm greenhouse climates, punctuated by a series of rapid warming and ocean acidification events known as "hyperthermals", thought to have been paced or triggered by orbital cycles. While these hyperthermals, such as the Paleocene Eocene Thermal Maximum (PETM), have been studied in great detail, the background low-amplitude cycles seen in carbon and oxygen-isotope records throughout the Paleocene-Eocene have hitherto not been resolved. Here we present a 7.7 million year (myr) long, high-resolution, orbitally-tuned, benthic foraminiferal stable-isotope record spanning the late Paleocene and early Eocene interval (~52.5 - 60.5 Ma) from Ocean Drilling Program (ODP) Site 1262, South Atlantic. This high resolution (~2-4 kyr) record allows the changing character and phasing of orbitally-modulated cycles to be studied in unprecedented detail as it reflects the long-term trend in carbon cycle and climate over this interval. The main pacemaker in the benthic oxygen-isotope (d18O) and carbon-isotope (d13C) records from ODP Site 1262, are the long (405 kyr) and short (100 kyr) eccentricity cycles, and precession (21 kyr). Obliquity (41 kyr) is almost absent throughout the section except for a few brief intervals where it has a relatively weak influence. During the course of the Early Paleogene record, and particularly in the latest Paleocene, eccentricity-paced negative carbon-isotope excursions (d13C, CIEs) and coeval negative oxygen-isotope (d18O) excursions correspond to low carbonate (CaCO3) and coarse fraction (%CF) values due to increased carbonate dissolution, suggesting shoaling of the lysocline and accompanied changes in the global exogenic carbon cycle. These negative CIEs and d18O events coincide with maxima in eccentricity, with changes in d18O leading changes in d13C by ~6 (±5) kyr in the 405-kyr band and by ~3 (±1) kyr in the higher frequency 100-kyr band on average. However, these phase lags are not constant, with the lag in the 405-kyr band extending from ~4 (±5) kyr to ~21 (±2) kyr from the late Paleocene to the early Eocene, suggesting a progressively weaker coupling of climate and the carbon-cycle with time. The higher amplitude 405-kyr cycles in the latest Paleocene are associated with changes in bottom water temperature of 2-4ºC, while the most prominent 100 kyr-paced cycles can be accompanied by changes of up to 1.5ºC. Comparison of the 1262 record with a lower resolution, but orbitally-tuned benthic record for Site 1209 in the Pacific allows for verification of key features of the benthic isotope records which are global in scale including a key warming step at 57.7 Ma.