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Astronomical (or Milanković) forcing of the Earth system is key to understanding rhythmic climate change on time scales ≳104 y. Paleoceanographic and paleoclimatological applications concerned with past astronomical forcing rely on astronomical calculations (solutions), which represent the backbone of cyclostratigraphy and astrochronology. Here we present state‐of‐the‐art astronomical solutions over the past 3.5 Gyr. Our goal is to provide tuning targets and templates for interpreting deep‐time cyclostratigraphic records and designing external forcing functions in climate models. Our approach yields internally consistent orbital and precession‐tilt solutions, including fundamental solar system frequencies, orbital eccentricity and inclination, lunar distance, luni‐solar precession rate, Earth's obliquity, and climatic precession. Contrary to expectations, we find that the long eccentricity cycle (LEC) (previously assumed stable and labeled "metronome," recent period ∼405 kyr), can become unstable on long time scales. Our results reveal episodes during which the LEC is very weak or absent and Earth's orbital eccentricity and climate‐forcing spectrum are unrecognizable compared to the recent past. For the ratio of eccentricity‐to‐inclination amplitude modulation (recent individual periods of ~2.4 and ~1.2 Myr, frequently observable in paleorecords) we find a wide distribution around the recent 2:1 ratio, that is, the system is not restricted to a 2:1 or 1:1 resonance state. Our computations show that Earth's obliquity was lower and its amplitude (variation around the mean) significantly reduced in the past. We therefore predict weaker climate forcing at obliquity frequencies in deep time and a trend toward reduced obliquity power with age in stratigraphic records. For deep‐time stratigraphic and modeling applications, the orbital parameters of our 3.5‐Gyr integrations are made available at 400‐year resolution. Key Points: We provide orbital eccentricity, inclination, oliquity, and climatic precession for use in paleostudies/climate models over the past 3.5 GyrThe long eccentricity cycle (previously used as "metronome") can become unstable on long time scalesEarth's past obliquity forcing/amplitude was significantly reduced. We predict reduced obliquity power with age in stratigraphic records [ABSTRACT FROM AUTHOR]

Variations in solar insolation caused by changes in the Earth's orbit—specifically its eccentricity, obliquity, and precession—can leave discernible marks on the geologic record. Astrochronology leverages these markers to establish a direct connection between chronological measurements and different facets of climate change as recorded in marine sediments. This approach offers a unique window into the Earth's climate system and the construction of high-resolution, continuous time scales. Our study involves comprehensive bulk carbonate analyses of 390 discrete samples from core SCS1, which was retrieved from the deep-sea floor of the northern South China Sea. By utilizing carbonate stratigraphic data, we have developed a carbonate stratigraphic age model. This was achieved by aligning the carbonate sequence from core SCS1 with the established carbonate standard stratigraphic time scale of the South China Sea. Subsequently, we construct an astronomically tuned time scale based on this age model. Our findings indicate that sediment records in this core have been predominantly influenced by a 20,000-year cycle (precession cycle) throughout the Late Pleistocene. We have developed an astronomical time scale extending back approximately 110,000 years from the present, with a resolution of 280 years, by tuning the carbonate record to the precession curve. Time-domain spectral analysis of the tuned carbonate time series, alongside the consistent comparability of the early Holocene low-carbonate event (11–8 kyr), underscores the reliability of our astronomical time scale. Our age model exposes intricate variations in carbonate deposition, epitomizing a typical "Pacific-type" carbonate cycle. Previous research has illustrated that precession forcing predominantly influences productivity changes in the South China Sea. The pronounced precession-related cycle observed in our record suggests that changes in productivity significantly impact carbonate content in the area under study. Furthermore, the clear precession period identified in the carbonate record of core SCS1 reflects the response of low-latitude processes to orbital parameters, implying that carbonate deposition and preservation in core SCS1 are chiefly influenced by the interplay between the Intertropical Convergence Zone (ITCZ) and the monsoon system within the precession band. Our astronomical time scale is poised to enhance paleoceanographic, paleoclimatic, and correlation studies further. Additionally, the independent evidence we provide for using proxy records for astronomical age calibration of marine sediments lends additional support to similar methods of astronomical tuning. [ABSTRACT FROM AUTHOR]

The late Asbian appears to mark the initial, well‐documented, onset of far‐field glacio‐eustatic changes in equatorial Mississippian strata. This work unravels the nature of cyclicity in upper Asbian shallow marine carbonates, using a combination of petrographic study, rock magnetic proxies and astrochronological testing on samples from the Trowbarrow section, NW England. Rock magnetic data express the content of two types of siliciclastic sources; a marine‐delivered magnetite‐dominated source, and an eolian‐delivered, hematite‐dominated source. The eolian‐sourced material generally peaked during regressive and low‐stand parts of the carbonate rhythms. Astrochronologic testing methods based around the average spectral misfit and TimeOpt methodology show the magnetite abundance proxies are principally carrying the astronomically forced signal. Two likely sedimentation rate models are derived from the five better magnetic proxies using evolutive methods. In addition, a set of three likely major hiatus levels are inferred in the sedimentation rate models, based on testing possible major hiatus scenarios with TimeOpt methods, using eccentricity modulation. From these, using the three best proxies, an average astrochronologic duration for the Trowbarrow section suggests a late Asbian duration of 1976 ± 86 kyr (1σ), and a basal late Asbian age of 334.48 ± 0.35 Ma (2σ). Coupled atmosphere‐ocean models for the late Paleozoic, suggest that lows in short eccentricity correspond to glacials, when inferred delivery of siliciclastic sediment to the carbonate ramp is generally at a maximum. The glacial and lower sea‐level intervals also coincide with maximum delivery of eolian siliciclastics, likely linked to increased aridity and less vegetation cover on adjacent and distal parts of Laurentia. Plain Language Summary: Around 332–333 million years ago changes in sea‐level driven by changes in polar ice volume were an important control on the sedimentation patterns through time in carbonates from low paleolatitudes. Understanding the pacing of these changes has implications for timescales and paleoceanographic processes. These cyclical changes in carbonate lithology are related to changes in magnetic properties within the late Asbian (late Visean) section at Trowbarrow in NW England. The magnetic changes principally express differences in the small content of silica‐based clastics, but also reflect changing Fe‐oxide mineralogy between times of hematite‐rich and magnetite‐rich clastic input. The changes are responding to differences in eolian delivery and marine dispersal of the clastics. Eolian delivery of clastics was at its peak near sea‐level lowstands, when nearby terrestrial systems were the most arid and supplying the most dust. Statistical assessments show that the magnetite abundance signal principally expresses changes in astronomical eccentricity. Primarily using the expected eccentricity pacing, two age models are constructed, which includes three levels of detectable hiatus in the section. Using these two age models and the three best magnetic proxies, the average late Asbian duration is 1976 ± 86 kyr, with the base of the late Asbian at 334.48 ± 0.35 Ma. Key Points: Rock magnetic properties show the included siliciclastics are from hematite‐rich eolian dust and marine‐dispersed sourcesThe magnetite mineral abundance proxies principally carry the primary eccentricity‐driven astronomical signalAn astrochronology for the late Asbian indicates its duration is 1976 ± 86 kyr [ABSTRACT FROM AUTHOR]

A cyclostratigraphic study of the Late Precambrian Zhuya Group (Nikolskoye and Chencha Formations), and Torgo formation in the southern part of the Siberian Platform was carried out to determine the duration of the C-isotope anomaly imprinted in them. The similarity of the ratios of the period lengths of the cyclic components of the magnetic susceptibility in the coeval deposits of the remote sections of the Nikol'skoye and Torgo Formations indicates the connection between the revealed cyclicity and the basin-scale environment changes. According to the astrochronological model, the duration of the formation of the studied intervals of the Nikol'skoye (57 m) and Chencha (147 m) formations was 850 and 2500 ky, respectively. Extrapolation of the data obtained shows that the duration of the C-isotope anomaly of the Zhuya Group in the Vendian reference section on the Ura uplift was about 10 My, which is consistent with most estimates of the Shuram anomaly's duration and its stratigraphic analogues. [ABSTRACT FROM AUTHOR]

Over the last 66 million years, Earth has undergone dramatic climate changes, shifting from a warm greenhouse to the more recent cold icehouse with polar ice caps in both hemispheres. Geological records show that the transition between these equilibrium states caused significant long‐term eustatic sea‐level and atmospheric CO2 decline paced by external orbital motions. Such eustatic variability influenced the stacking pattern of sedimentary successions, generating cyclic sequence boundaries that may be globally correlated. However, the impact of such oscillation along the Brazilian margin is largely unknown. This study used the natural gamma‐ray log from a well (ES‐2) at the offshore Espírito Santos Basin (western South Atlantic) measured between late‐Palaeocene and late‐Miocene. Null hypothesis tests ‐ evolutionary Average Spectral Misfit and Correlation Coefficient of no orbital modulation ‐ were executed to confirm the influence of astronomical parameters. The evolutionary Time Optimization algorithm was used to extract the sedimentation rate and depositional time. The anchored timescale shows a chronological interval placed between 58.97 and 7.72 ± 0.1 Ma (mid‐Thanetian – late Tortonian), mostly influenced by long‐eccentricity and short‐eccentricity (405 kyr and ca 100 kyr, respectively) and obliquity (ca 40 kyr) and their respective amplitude modulations (ca 2.4 Myr and 1.2 Myr). Applying the Integrated Prediction Error Filter Analysis and a high‐resolution age model, this study identified main depositional trends through time and correlated them to global sea‐level change. The correlation indicates that several intervals of global sea‐level reduction agree with a regressive trend at the ES‐2 site, but this relation is affected during enhanced regional tectonic activity intervals, as related to the emplacement of the Abrolhos Archipelago. The strategy adopted here is a way to join cyclostratigraphy and sequence stratigraphy, and promotes high‐resolution local‐to‐global correlation by identifying key stratigraphic surfaces. This will be relevant for palaeoclimatic studies and the geoscientific industry. [ABSTRACT FROM AUTHOR]

Variations in solar insolation caused by changes in the Earth’s orbit—specifically its eccentricity, obliquity, and precession—can leave discernible marks on the geologic record. Astrochronology leverages these markers to establish a direct connection between chronological measurements and different facets of climate change as recorded in marine sediments. This approach offers a unique window into the Earth’s climate system and the construction of high-resolution, continuous time scales. Our study involves comprehensive bulk carbonate analyses of 390 discrete samples from core SCS1, which was retrieved from the deep-sea floor of the northern South China Sea. By utilizing carbonate stratigraphic data, we have developed a carbonate stratigraphic age model. This was achieved by aligning the carbonate sequence from core SCS1 with the established carbonate standard stratigraphic time scale of the South China Sea. Subsequently, we construct an astronomically tuned time scale based on this age model. Our findings indicate that sediment records in this core have been predominantly influenced by a 20,000-year cycle (precession cycle) throughout the Late Pleistocene. We have developed an astronomical time scale extending back approximately 110,000 years from the present, with a resolution of 280 years, by tuning the carbonate record to the precession curve. Time-domain spectral analysis of the tuned carbonate time series, alongside the consistent comparability of the early Holocene low-carbonate event (11–8 kyr), underscores the reliability of our astronomical time scale. Our age model exposes intricate variations in carbonate deposition, epitomizing a typical “Pacific-type” carbonate cycle. Previous research has illustrated that precession forcing predominantly influences productivity changes in the South China Sea. The pronounced precession-related cycle observed in our record suggests that changes in productivity significantly impact carbonate content in the area under study. Furthermore, the clear precession period identified in the carbonate record of core SCS1 reflects the response of low-latitude processes to orbital parameters, implying that carbonate deposition and preservation in core SCS1 are chiefly influenced by the interplay between the Intertropical Convergence Zone (ITCZ) and the monsoon system within the precession band. Our astronomical time scale is poised to enhance paleoceanographic, paleoclimatic, and correlation studies further. Additionally, the independent evidence we provide for using proxy records for astronomical age calibration of marine sediments lends additional support to similar methods of astronomical tuning.

[Display omitted] • Newly discovered Carboniferous-Permian terrestrial profile through astrochronology. • A global negative δ13C excursion at Carboniferous-Permian Boundary was confirmed. • Revised the stratigraphic division in Junggar Basin, NW China. The Carboniferous–Permian Boundary (CPB) is a major stratigraphic boundary and a marker for global stratigraphic correlation. However, the delimitation and global correlation of the CPB is hindered by the erosion during the Late Paleozoic Ice Age. Several carbonate platforms show a negative carbon isotope excursion (NCIE) in response to the CPB, which has great potential for the delimitation of this boundary. However, the response of terrestrial profiles to the CPB is unclear, and the global synchroneity of this NCIE is controversial. We studied a high paleolatitude section to evaluating the feasibility of the NCIE for delimitating CPB. We used astrochronological analysis of the 340 m Gamma Ray log of the Fengcheng Formation in Mahu Sag, Junggar Basin, northwest China, where the CPB may have been recorded. We constructed a high-resolution chronostratigraphic framework for the Fengcheng Formation, which precisely defines the chronostratigraphic attribution of the Fengcheng Formation as the Gzhelian–Asselian, and confirms that the CPB is recorded in the Fengcheng Formation. In addition, a global correlation of carbon isotope profiles revealed a negative excursion in terrestrial carbon isotope profiles across the CPB, which is consistent with the characteristics of NCIEs in several marine profiles. The similarity of the NCIE records supports their global synchrony and confirms that they can be used to delimit the CPB in terrestrial sections. Combining the astronomical time scale and the carbon isotope profile, we constrain the position of the CPB to the depth range of 4694.84–4703.56 m, with 4698.9 m as a preliminary estimate of the CPB. This new astronomical timescale and the stratigraphic position of the CPB enable the revision of the chronostratigraphic attribution of the terrestrial strata in the Junggar Basin. Overall, our results contribute to studies of the Carboniferous–Permian global carbon cycle, high-latitude glaciation, eustatic fluctuations, global volcanism, and their potential relationships. [ABSTRACT FROM AUTHOR]

Mounting evidence indicates that the orbital period of the solar system's movement through the Milky Way has had a controlling effect on processes of the Earth's system throughout the Phanerozoic. To decipher the response of a given terrestrial basin's rhythms to galactic dynamics, for the first time, we report long-term cycles recorded in the Mesozoic Ordos Basin (Central China). The astronomical time scale (ATS) was established for each successive sedimentary sequence, and the duration of unconformity episodes was estimated based on the chronological constraints. Using this timescale, time-series analysis of the deposition rate is carried out through the Mesozoic Ordos Basin, which reveals compelling periodicities of 93, 33, 9, 3–5, and 2.4 Myr. The radial solar system motions around the galactic centre and plate tectonic cycles act cooperatively to impact the magmatic tempo of the Qinling orogenic belt and the 93-Myr depositional cycle of the Mesozoic Ordos Basin. The Mesozoic 33-Myr cycle is a sedimentary response to the half-period of the solar system's vertical oscillation about the galactic plane. A rational explanation is that galactic oscillation affects mantle convection, which is responsible for periodic asthenospheric upwelling and ultimately controls the vertical crust oscillation of the Ordos Basin. Mesozoic 9-Myr and the higher-frequency 3–5 and 2.4-Myr depositional cycles can be sedimentary responses to the Earth's orbital eccentricity, which affected the temporal variation in depositional environments in the Ordos Basin. Apart from the galactic-geologic correlations, long-term cycles recorded within a sedimentary basin should also consider the tectonically driven mechanisms at these timescales. This framework provides a new perspective for revealing the astronomical origin of Earth's rhythms. [ABSTRACT FROM AUTHOR]

The Oceanic Anoxic Event 2 (OAE 2) is widely regarded as one of the most significant global-scale biological and environmental perturbations in the Mesozoic Era. However, the duration and driving mechanisms of this event at southern high latitudes remain largely unknown due to a lack of available geological records. Here, we present a cyclostratigraphic analysis of high-resolution records of lightness variability (L*) and gamma-ray attenuation (GRA) bulk density, which are associated with changes of marine primary productivity and continental weathering, respectively, from Site U1516 located in the Mentelle Basin, offshore southwest Australia. This analysis permits establishment of an astronomical time framework for a stratigraphic interval of 455.205–485.24 m rCCSF (revised Core Composite Depth below Sea Floor) by tuning the 100 kyr filter to short eccentricity. The studied section encompasses the entire OAE 2 interval at the depth of 460.13–473.94 m rCCSF. Based on the established high-resolution astronomical time scale using astronomical tuning of L* records to the short eccentricity cycles (100 kyr), the duration of OAE 2 is estimated to be ∼990 kyr at Site U1516. A relatively high amplitude of short eccentricity occurred at the build-up stage, accompanied by a gradual rise in obliquity amplitude during the recovery phase of the OAE 2. Combining previous proposals for enhanced oceanic water stratification and terrestrial weathering, we suggest that obliquity, coupled with short eccentricity, paced the evolution of this event at southern high latitudes by controlling insolation changes received by the Earth's surface. • The OAE 2 duration is ∼990 kyr at southern high latitudes. • Short orbital eccentricity amplified the large igneous province affection at the OAE 2 build-up stage. • The orbital obliquity paced the OAE 2 recovery stage at southern high latitudes. [ABSTRACT FROM AUTHOR]

The chaotic behavior of the Solar System prevents the prediction of the precise evolution of the planetary secular frequencies. Here we use four cyclostratigraphic sequences, ∼259 Ma Wujiaping Formation, ∼455 Ma Pingliang Formation, ∼655 Ma Datangpo Formation and ∼2,465 Ma Dales Gorge Member, and Bayesian inversion to provide powerful geological constraints to this problem. The inversion provides constraining estimates for the Solar System fundamental secular frequencies g1, g2, g3, g4, and g5, and the Earth's precession rate k from 105.26 ± 2.68 (2σ) arcseconds/year at ∼2,465 Ma to 55.86 ± 2.60 (2σ) arcseconds/year at ∼259 Ma. Stochastic monotone interpolation enables the reconstruction of Earth‐Moon distance from 2.5 billion years to the present. Calculation of tidal dissipation supports the ocean model before 1.4 Ga, but is outside the error range after ∼1.8 Ga, suggesting lower tidal dissipation in the early Proterozoic Eon, and a possible high value in the early Paleozoic. Plain Language Summary: The chaotic history of the Solar System imposes unknown uncertainties on the fundamental secular frequencies of the planets over most of geologic time. This is complicated by a lack of knowledge about the evolution of Earth‐Moon distance, Earth's length of day and tidal dissipation. Geological evidence provides powerful constraints on all of these parameters. To shed light on the parameters, here we carry out Bayesian inversion of fundamental secular frequencies and Earth precession rate on four cyclostratigraphic sequences, and stochastic monotone interpolation to reconstruct Earth‐Moon distance from 2.5 billion years ago to present. From these results we estimate the Earth's tidal dissipation variation, which we compare with theoretical models. Our results provide critical geological constraints for paleotidal simulation, and shine a light on the unique potential of cyclostratigraphy to constrain Earth‐Moon system history across geologic time. Key Points: We obtain new estimates of Earth‐Moon and Solar System dynamical parameters from cyclostratigraphy at four ages from ∼2.5 Ga to ∼259 MaWe interpolate Earth‐Moon distances inferred from the cyclostratigraphy to reconstruct a continuous history from ∼2.5 Ga to the presentWe estimate Earth's tidal dissipation variations from ∼2.5 Ga to the present [ABSTRACT FROM AUTHOR]

The Ediacaran ocean recorded the largest negative carbonate carbon isotope (δ13C carb) excursion in Earth's history, the Shuram Excursion (SE). The relatively invariant character of organic carbon isotope (δ13C org) profiles during the SE has been attributed to buffering by a large dissolved organic carbon (DOC) reservoir in the ocean. However, recent studies suggest that the DOC buffering may have been highly heterogeneous, a hypothesis that can be tested by assessing variability in the spatial and temporal ranges of δ13C org buffering during the SE. In this study, we evaluated δ13C org and δ13C carb records from multiple regions globally to test the heterogeneous buffering hypothesis. Making use of a high-precision astrochronological framework, we found that the buffering effect of DOC persisted for ∼2.7 Myr in Oman, ∼4.9 Myr in South China, and ∼5.9 Myr in Australia, demonstrating its temporal heterogeneity. Heterogeneous buffering is also demonstrated at a small spatial scale for South China sections based on a correlation framework subdividing the SE into three intervals: EN3a (δ13C carb decline from baseline to nadir), EN3b (δ13C carb stabilized at nadir), and EN3c (δ13C carb recovery from nadir value). The duration of δ13C org buffering increased with water depth from shallow neritic to deep pelagic areas. The buffering effect terminated within EN3a in inner-shelf areas, within EN3b in an intra-shelf basin, and within EN3c in slope areas. Spatial variation in the offset between δ13C carb and δ13C org values (Δ13C (carb-org)) is consistent with multiple sources of sedimentary organic matter. An average of ∼26 ‰ in inner-shelf areas implies mainly fresh phytoplankton debris, whereas an average of ∼18 ‰ in slope areas is consistent with dominance of DOC, which is thought to have been present in abundance in deeper anoxic watermasses. Thus, our study supports a large DOC reservoir in the late Ediacaran ocean that led to heterogeneous buffering during the SE at both basinal and global scales. Large shallow-to-deep oceanic δ13C carb and δ13C org gradients of similar magnitude existed both before and during the SE, indicating that the circulation and productivity dynamics of the Ediacaran ocean were not significantly changed by the SE. The downward expansion of oxidant-rich surface watermasses during the SE improved the ventilation of shelf oceans while leaving the deep ocean anoxic, setting the stage for rapid biological evolution on continental shelves during the Cambrian Explosion. • Shuram Excursion characterized by DOC-buffered and -non-buffered intervals. • DOC buffering lasted ∼2.7 Myr (Oman), ∼4.9 Myr (China), and ∼ 5.9 Myr (Australia). • DOC buffering shows strong facies-dependent pattern & increases with water depth. • Gradual oxidation of the Ediacaran ocean explains observed C cycle patterns. • Our study provides new insights into carbon cycling in the Ediacaran ocean. [ABSTRACT FROM AUTHOR]

The climatic transitions during the Miocene‐Pliocene epochs had significant impacts on the worldwide biological diversity and were associated with large turnovers of continental vegetation and fauna. Previous studies have shown that late Miocene cooling and continental aridification which was initiated 7 Ma reversed to warm conditions across the Miocene‐Pliocene Boundary ∼5.3 Ma. Here, we present detailed orbital pacing of Asian monsoon deposits to constrain further the global climate change during this period. We produce high‐resolution magnetic susceptibility records which reveal that the 1.2 Myr obliquity modulation would have been the main driving factor of the cooling and warming that occurred ∼7 and 5.3 Ma, respectively. The Tibetan rise and closures of the Panama and Indonesian seaways enhanced the impact of the 405 Kyr eccentricity cycles to an oscillatory climatic state while the Northern Hemisphere glaciations were increasing from 4 to 2.5 Ma. Plain Language Summary: For the first time, we point out eolian sediments from Chinese Loess Plateau through the Asian monsoon is primarily respond to the long‐period evolving dynamics of Earth‐Mars obliquity modulation since the late Miocene. Our study deciphers the presence of oscillatory sedimentary patterns resulting from the 1.2 Myr band were responsible for the global climate transition during the aridification and cooling at ∼7 Ma and warming at ∼5.3 Ma. Our new discovery challenges the previous hypothesis that carbon circulations involving both the marine and terrestrial carbon reservoirs were instrumental in driving late Miocene climate cooling and warming, which provide a valuable analog for the climate prediction of Pliocene‐like temperature level in the coming decades. Key Points: We investigate magnetostratigraphy and cyclostratigraphy of Chinese Loess Plateau aeolian sediments since the late MioceneThe strong imprint of 1.2 Myr obliquity was responsible for the global climate transition during ∼7 Ma cooling and 5.3 Ma warmingThe 1.2 Myr obliquity and 405 Kyr eccentricity modulations played key roles in the paleoclimate before and after 4 Ma, respectively [ABSTRACT FROM AUTHOR]

[Display omitted] • The astronomical time scale of the upper 4th Mbr of Shahejie Fm, Dongpu Depression is established. • The ATS and isotope excursions confirm that Doubthouse climate occurred in lacustrine basins. • The Doubthouse climate influences the type and abundance of hydrocarbon-forming organisms. • Paleo-productivity, sedimentation rate and preservation control OM enrichment in Doubthouse climate. The Doubthouse climate is a typical cooling climate between the Early Eocene Climate Optimum (EECO) and the Middle Eocene Climate Optimum (MECO). The precise timing of this climate's occurrence and its effects on the carbon cycle and organic matter enrichment remain unknown. This work studied the upper 4th Mbr of Shahejie Fm in the Eocene Dongpu Depression (DD), Bohai Bay Basin, to reveal the controlling effect of the Doubthouse climate on organic matter enrichment. The astronomical time scale (ATS) of the upper 4th Mbr of Shahejie Fm in the DD is established as 41.38–43.31 Ma (±0.1 Myr) using a natural gamma logging curve. The simulated sedimentation rate is 14.6 cm/kyr. The organic matter is mostly from freshwater algae such as green algae, cyanobacteria, and dinoflagellates. The positive excursion (4.07 ‰) of δ13C corresponds to the increased weathering intensity and the humid climate, which benefit algae growth. The paleo-productivity and sedimentation rates during the Doubthouse climate period increased. Besides, the cooling climate inhibited the respiration of the algae. Therefore, CO 2 intake > organic carbon consumption was recorded as δ13C excursion. Hence, we propose that the doubthouse climate is the controlling factor of organic matter enrichment. [ABSTRACT FROM AUTHOR]

The Early Turonian interval represents a unique confluence of climatic and oceanographic conditions including peak surface temperatures, high greenhouse‐gas concentrations, and maximum Phanerozoic sea level. The susceptibility of this climate mode to astronomical insolation forcing remains poorly understood partly due to a limited time control and unknown phasing of astronomical cycles in this interval. Here, we offer a refined astrochronology of the Early Turonian based on laterally consistent precession signals preserved in offshore strata of the Bohemian Cretaceous Basin (central Europe). Pristine amplitude modulation verified through interference patterns in depth‐frequency plots provides a robust indication of ∼100 and 405‐kyr eccentricity phases (maxima and minima) that are pinned to ammonite biozones and new carbon‐isotope data from two cores. The Early Turonian is estimated as 885 ± 41 (2σ) thousand years (kyr) in duration, with the Cenomanian/Turonian boundary predating the first Turonian 405‐kyr maximum (no. 232 in the Geological Time Scale 2020) by 82 ± 70 (2σ) kyr. The results support a possible link of the recovery from Oceanic Anoxic Event II to increasing magnitude of seasonal insolation extremes due to rising eccentricity on 405‐kyr and million‐year (Myr) time scales. Superimposed upon this trend are small‐scale carbon‐isotope anomalies the pacing of which passes from ∼110 kyr, resembling short eccentricity, to ∼170 kyr, possibly related to obliquity modulation. This eccentricity‐to‐obliquity transition, paralleling the rising phase of Myr‐scale eccentricity, suggests decoupling of the carbon‐cycle perturbations from low‐latitude seasonal insolation. Mid‐latitude to high‐latitude carbon reservoirs became involved toward the Middle Turonian. Key Points: Well‐preserved precessional and eccentricity signals constrain the duration of the Early Turonian to 885 ± 41 kyrRecovery from OAE II is superimposed upon rising phases of the 405 and ∼2.4‐Myr eccentricityShort‐term carbon‐isotope anomalies decouple from low‐latitude insolation control toward the Middle Turonian [ABSTRACT FROM AUTHOR]

This research analyzes the cyclostratigraphy of the lacustrine Dabeigou Formation (DBG) of early Jehol Biota age (∼130–135 Ma) in the Luanping Basin, northern China. A high-resolution (2 cm interval), 117.82-m-long magnetic susceptibility (MS) stratigraphic series was measured along the Yushuxia section. MS is positively correlated with thorium, potassium and uranium concentrations associated with gamma ray intensity, and represents a proxy for detrital influx to the Luanping Basin. Power spectral analysis identifies a hierarchy of sedimentary cycles with wavelengths of 16.38 m, 5.85–3.28 m, 1.88–1.33 m, and 0.98–0.7 m, which are interpreted to represent Earth’s orbital eccentricity, obliquity and precession index cycles. Objective testing of the MS series supports the interpretation of Milankovitch cycles, indicating an average sedimentation rate of 4.642–4.723 cm/kyr. A floating astronomical time scale with a duration of 2478 kyr is established from interpreted 405 kyr long orbital eccentricity cycles along the MS series. The 405-kyr tuned DBG MS time series closely matches the predicted orbital eccentricity of the La2004 astronomical solution from 130.787 to 133.265 Ma, providing independent temporal constraints on early stage Jehol Biota evolution. Finally, this estimated time interval for the DBG MS time series indicates that it occurred entirely within the Weissert Event.

The upper Silurian, and especially Pridoli epoch is a critical interval for the understanding the evolution of Earth's biota, since it witnessed series of powerful extinction events, global reorganizations of paleocommunities, and expansion of new clades, which assumed dominance in the subsequent Devonian period. The stratigraphic record of the eastern part of the Silurian Baltic Basin represents an excellent candidate for the fine scale analysis of paleoecological and paleoceanographic dynamics. Therefore we presenting here stratigraphic record of the Milaičiai-103 core (south western Lithuania) of conodonts, brachiopods, δ 13 C carb , δ 18 O carb and a series of various geochemical and geophysical proxies, most of which were sampled at a very high resolution (~11 Ka), spanning uppermost Ludlow, Pridoli, and the lowermost Devonian. The analysis revealed that the Pridoli was characterized by four distinct long-term dynamic states here named: i) Normal Pridoli I, ii) Šilalė negative carbon isotopic excursion and extinction event, iii) Normal Pridoli II, and iv) Klonk positive stable carbon isotopic event and excursion. The most significant change in most variables is detected approximately in the middle of the Pridoli, at the beginning of the Delotaxis detorta Zone, at the recovery after Šilalė event of conodonts, and at the onset of collapse of brachiopod communities. The analysis of dynamic complexity revealed the strong evidence for the presence of ~405 Ka metronome Milankovitch cycles in the record of δ 13 C carb , which constrains the duration of the Pridoli epoch to 4.3 ± 0.2 Ma. The recurrence plot analyses revealed deterministic coordination between δ 13 C carb and conodont paleocommunity dynamics at all scales. Finally lead-lag analysis, using conditional joint recurrence, revealed that conodont dynamics, as a rule, were driven by perturbations in the carbon cycle, although Šilalė event interval shown opposite pattern, thus confirming the unusual nature of this previously unrecognized coordinated climatic and biotic event. Unlabelled Image • The biogeochemical and paleoecological record of the Pridoli is characterized by four dynamic states. • Šilalė event of coordinated conodont extinctions and negative carbon isotopic excursion is distinguished in the lower Pridoli. • Pronounced ~405 Ka cycles in the time series of dynamic complexity of δ 13 C carb enable accurate estimation of the duration of Pridoli. • Conodont communities and stable carbon isotopic ratios show joint coordination at a range of time scales. [ABSTRACT FROM AUTHOR]

One of the clocks that record the Earth history is (quasi-) periodic astronomical cycles. These cycles influence the climate that can be ultimately stored in sedimentary rocks. By cracking these (quasi-) periodic sedimentation signals, high resolution astronomical time scale (ATS) can be obtained. Paleoclimate proxies are widely used to extract astronomical cycles. However different proxies may respond differently to astronomical signals and non-astronomical noises including tectonics, diagenesis, and measurement error among others. Astronomical time scale constructed based on a single proxy where its signal-to-noise ratio is low may have uncertainty that is difficult to evaluate but can be revealed by utilizing other proxies. Here, we test eight astronomical age models using two astrochronological methods from four paleoclimate proxies (i.e., color reflection L* and b*, natural gamma radiation, and bulk density) from the Turonian to the Coniacian of the Cretaceous Period at the Demerara Rise in the equatorial Atlantic. The two astrochronological methods are time calibration using long eccentricity bandpass filtering (E1 bandpass) and tracking the long eccentricity from evolutive harmonic analysis (tracking EHA). The statistical mean and standard deviation of four age models from the four proxies are calculated to construct one integrated age model with age uncertainty in each method. Results demonstrate that extracting astronomical signals from multiple paleoclimate proxies is a valid method to estimate age model uncertainties. Anchored at the Cenomanian/Turonian boundary with an age of 93.9 ​± ​0.15 ​Ma from biostratigraphy, the ages for CC11/CC12 (calcareous nannofossil zones), Turonian/Coniacian (CC12/CC13), CC13/CC14, and Coniacian/Santonian boundaries are 91.25 ​± ​0.20 ​Ma, 89.87 ​± ​0.20 ​Ma, 86.36 ​± ​0.33 ​Ma, and 86.03 ​± ​0.32 ​Ma in E1 bandpass method, compared with 91.17 ​± ​0.36 ​Ma, 89.74 ​± ​0.38 ​Ma, 86.13 ​± ​1.31 ​Ma, and 85.80 ​± ​1.33 ​Ma respectively in tracking EHA method. These results are consistent with previous studies within error and provide a reliable estimation of uncertainties of the ages. Image 1 • Nine million-year astronomical time scale constructed from late Cenomanian to Coniacian. • Four paleoclimate proxies provide consistent results. • A method of estimating uncertainties of astronomical time scale is proposed. [ABSTRACT FROM AUTHOR]

Astrochronology depends on the faithful record of insolation forcing in climatic proxies, including the carbon isotope composition measured on bulk carbonates (δ13Ccarb). In marginal basins close to carbonate platforms, the source of carbonate is varied, which can impact the record of the astronomical cycles in the δ13Ccarb signal. We compare here the δ13Ccarb values together with detrital and weathering proxies before and during a crisis in the platform carbonate production (Weissert event, Valanginian, ~135 Ma) to document how a change in the carbonate source can affect the record of the orbital forcing by the carbon isotope system. The level of burial diagenesis was insufficient to alter the clay mineral assemblages, which are linked to cyclic changes in weathering conditions. The δ13Ccarb values correspond to the values measured in other parts of the basin, which experienced various levels of burial diagenesis, suggesting that they also reflect a paleoenvironmental signal. In marl beds, the δ13Ccarb values increase with detrital and kaolinite content, suggesting that humid/arid cycles controlled the evolution of the δ13Ccarb signal in marl beds. Before the Weissert event, the δ13Ccarb values in the limestone beds increase with CaCO3 content and arid conditions. This can reflect the change of type of carbonate produced in shallow‐marine environments and exported to the basin. These environmental changes disrupted the record of the eccentricity cycles in the δ13Ccarb signal. The sources of carbonate must therefore be clearly identified and documented before using the δ13Ccarb series for orbital tuning in hemipelagic areas close to carbonate platforms. Plain Language Summary: The Milankovitch cycles are periodic motions of the Earth's orbit at the origin of cyclic climatic changes recorded in strata. Regular decimetric alternations between marl and limestone strata deposited in deep seas are notably caused by humid‐arid cycles orbitally induced, which usually take ~20,000 yr to be deposited. Counting these strata cycles allows the duration of the geological periods to be calculated. The so‐called astronomical timescales depend on the faithful stratal record of the Milankovitch cycles. Carbon isotopes are used to build astronomical timescales despite sources of carbon are varied and often unconstrained. We compare here proxies from the continental weathering and erosion to the marine carbonate production recorded in marl‐limestone alternations. We show here that the different sources of carbonates—produced by organisms with variated ecological needs—disrupt the record of the Milankovitch cycles in the carbon isotopes. The sources of carbon in sediments have to be compared to additional climatic proxies before being used for astronomical timescales. In addition, we propose models to explain how the Milankovitch cycles can be recorded and disrupted in the proxies studied here. Key Points: The δ13Ccarb measured in hemipelagic marl and limestone beds shows opposite responses to eccentricity depending on the source of carbonatesA careful control of the source of carbonates should be done before using δ13Ccarb series for astronochronology in Mesozoic marginal basinsComparisons with the insolation models suggest that more carbonated intervals occurred at eccentricity maxima [ABSTRACT FROM AUTHOR]

Global perturbations to the Early Jurassic environment (~201 to ~174 Ma), notably during the Triassic-Jurassic transition and Toarcian Oceanic Anoxic Event, are well studied and largely associated with volcanogenic greenhouse gas emissions released by large igneous provinces. The long-term secular evolution, timing, and pacing of changes in the Early Jurassic carbon cycle that provide context for these events are thus far poorly understood due to a lack of continuous high-resolution δ13C data. Here we present a δ13CTOC record for the uppermost Rhaetian (Triassic) to Pliensbachian (Lower Jurassic), derived from a calcareous mudstone succession of the exceptionally expanded Llanbedr (Mochras Farm) borehole, Cardigan Bay Basin, Wales, United Kingdom. Combined with existing δ13CTOC data from the Toarcian, the compilation covers the entire Lower Jurassic. The dataset reproduces large-amplitude δ13CTOC excursions (>3‰) recognized elsewhere, at the Sinemurian-Pliensbachian transition and in the lower Toarcian serpentinum zone, as well as several previously identified medium-amplitude (~0.5 to 2‰) shifts in the Hettangian to Pliensbachian interval. In addition, multiple hitherto undiscovered isotope shifts of comparable amplitude and stratigraphic extent are recorded, demonstrating that those similar features described earlier from stratigraphically more limited sections are nonunique in a long-term context. These shifts are identified as long-eccentricity (~405-ky) orbital cycles. Orbital tuning of the δ13CTOC record provides the basis for an astrochronological duration estimate for the Pliensbachian and Sinemurian, giving implications for the duration of the Hettangian Stage. Overall the chemostratigraphy illustrates particular sensitivity of the marine carbon cycle to long-eccentricity orbital forcing. [ABSTRACT FROM AUTHOR]

Abstract Astronomically-forced insolation cycles ("Milankovitch cycles") serve as a primary control on climate, and when preserved in the stratigraphic record, they provide a high-resolution in situ chronometer. These celestial rhythms derive from the fundamental frequencies of the Solar System, and Earth's precession constant. The fundamental frequencies of Earth and Mars presently define a secular resonance of 2:1 (2.4 Myr to 1.2 Myr), and are hypothesized to have undergone a transition between 50–100 Ma, due to the chaotic behavior of the Solar System. In this study, a 15-Myr long cyclostratigraphic record from the mid-latitude Western Interior Seaway (WIS; spanning 82–97 Ma) is assembled to quantify eccentricity amplitude modulation (AM) and obliquity AM, which could reveal the 2:1 resonance when present. Ten high-precision radioisotopic dates from the study interval permit a rigorous anchoring of the floating astrochronologies for comparison with theoretical astronomical models. The analysis is complimented by the construction of an astronomically tuned δ 13 C org composite for the early Cenomanian-early Campanian, which allows a new assessment of linkages between million-year scale astronomical forcing and perturbations of the Late Cretaceous carbon cycle. Evaluation of the La2004 model reveals a switch of eccentricity modulation from 2.4-Myr cycles to a 1.2-Myr cycle from 90 to 86.5 Ma, followed by a return to a 2.4 Myr cycle in younger strata, compatible with observations from the WIS composite. These two resonance transitions are absent in the La2010d and La2011 models. Among 11 solutions calculated by Zeebe (2017) , some show resonance transitions during this period, but none of them match the geological record with respect to the observed long eccentricity modulation. The results of this study also suggest that positive carbon isotope excursions are closely related to obliquity power minima, but this interpretation will require further analysis for full confirmation. Highlights • Ten high-precision radioisotopic dates integrated with two cyclostratigaphic records. • New astronomically-calibrated carbon isotope composite produced. • 2.4-Myr and 1.2-Myr "grand cycles" are found in geological records from 97–82 Ma. • Two chaotic resonance transitions are identified in the Turonian–Santonian. • This study offers an opportunity for constraining the chaotic Solar System. [ABSTRACT FROM AUTHOR]

Abstract The geologic time scale serves as an essential instrument for reconstructing Earth history. Astrochronology, linking regular sedimentary alternations to theoretical quasi-periodic astronomical rhythms, often provides the highest resolution age models for strata that underlie the time scale. Although various methods for testing astronomically-tuned time scales exist, they often present challenges, such as the problem of circularity. Here, we introduce an approach to extract a reliable obliquity envelope from astronomically tuned data, avoiding the effects of frequency modulations that can artificially introduce astronomical beats. This approach includes (1) the application of a broad obliquity filter followed by (2) a Hilbert transform and (3) a low-pass filter of the amplitude envelope to (4) test the significance of correlation between amplitude envelope and astronomical solution. These data amplitudes provide a robust means to evaluate the climate response to obliquity forcing and, more specifically, to test the significance of correlation with the theoretical astronomical solution, in a manner similar to the phase-randomized surrogate approach previously introduced for the evaluation of precession tuning. Synthetic astronomical/ice-sheet models and several Quaternary climate proxy records – where obliquity can be a dominant component of astronomically driven climate variability – are used to demonstrate the feasibility of the proposed method and yield new insight into climate system evolution. Highlights • We develop a test for time scales based on the obliquity imprint. • We reconstruct robust obliquity amplitude variations from tuned time scales. • Methods are tested and discussed using several Quaternary datasets. [ABSTRACT FROM AUTHOR]

Abstract When Milankovitch cycles are preserved in the geologic record they provide a direct link between chronometer and climate change, and thus a remarkable opportunity to constrain the evolution of the surficial Earth System. The identification of such cycles has allowed exploration of the geologic record with unprecedented temporal resolution, and has spurred the development of a rich theoretical framework for climatic change. Accompanying these successes, however, has been a persistent skepticism: how does one reliably test for astronomical forcing/pacing in stratigraphic and paleoclimate data, especially when time is poorly constrained? From this perspective, it would seem that the merits and promise of astrochronology – a Phanerozoic time scale measured in 20,000 to 400,000 year increments – also serves as its Achilles heel, if the confirmation of such geologically short temporal rhythms defies rigorous hypothesis testing. The implications are substantial, since much of our understanding of paleoclimate change throughout the Cenozoic (and beyond) is firmly rooted in astrochronologic interpretation. In this study, a conceptual framework for assessing Earth System response to astronomical-insolation changes, and the propagation of that signal into the geologic record, is used as a guide to understand the nature of the problem of astrochronologic testing. This framework emphasizes three challenges – contamination, stratigraphic distortion , and temporal calibration. A statistical optimization method (TimeOpt; Meyers, 2015) is formulated as a solution to these three challenges, providing an approach for astrochronologic testing that objectively evaluates time scale uncertainty while simultaneously identifying an optimal model for climate and depositional system response to astronomical forcing. New extensions to the technique are presented, allowing explicit reconstruction of distortions to the primary forcing that are known to be omnipresent in the stratigraphic record. To illustrate the utility of this approach, it is applied to five well-studied stratigraphic series throughout the Phanerozoic, supporting their astronomical origin, and yielding constraints on the evolution of the Earth System and the astronomical solutions themselves. Future directions that build on this foundation are discussed, including the utility of process-based null models, approaches for Earth System transfer function reconstruction, and mapping out ancient Solar System behavior and Earth-Moon history using the geologic archive of Milankovitch cycles. The TimeOpt approach recognizes astronomy, geochronology, paleoclimatology and depositional system reconstruction as a unified geoscientific inverse problem. [ABSTRACT FROM AUTHOR]

Abstract Multiple proxies for paleoclimatic and paleoenvironmental change within sedimentary sequences have been developed; but understanding their relationships and their relative strengths or weaknesses are required to access a wealth of untapped paleoclimate information. We propose two main criteria for multiple proxy datasets to estimate their individual signal-to-noise levels and to decipher the relationship between multiple proxies. First, for proxies affected by similar processes, then their time-dependent changes should be similar. Second, a paleoclimate proxy that is more sensitive to an external forcing, such as astronomical forcing, is more useful than those that do not have such a response. We introduce two methods to evaluate these criteria: (1) hierarchical cluster analysis (HCA) probes the relationships among multiple proxies based on similarities of their oscillation patterns, and (2) power decomposition analysis (PDA) tests proxy sensitivity to external climate forcing. We evaluate 16 high-resolution paleoclimate proxies in detail for their applications in paleoclimatology from the marine Lower Triassic Daye Formation at the Daxiakou section in the Three Gorges region of South China, which has carbonate-claystone cycles deposited on an outer ramp. The proxies are spectral gamma ray (gamma-ray intensity, potassium, uranium, thorium, thorium/uranium and thorium/potassium), rock color lightness (L*), redness (a*) and yellowness (b*), magnetic susceptibility (measured in both laboratory and outcrop), anhysteretic remanent magnetization (ARM), lithologic rank, simplified lithologic rank and non-carbonate fraction, carbonate thickness and couplet thickness. Hierarchical cluster analysis (HCA) gathers these proxies into groups likely affected by the same process. The ARM and thorium/uranium proxies seem to reflect the hinterland-weathering process during the Early Triassic. Gamma-ray, potassium, uranium, thorium, magnetic susceptibility and non-carbonate fraction proxies refer to terrestrial input. The L*, a* and lithologic rank proxies indicate the productivity, the redox state and the relative sea level, respectively at this section. This case study contributes to the understanding of the sensitivity of these types of proxies within marine strata for deep-time paleoclimate and astronomical-tuned time scales. [ABSTRACT FROM AUTHOR]

Astronomical insolation forcing plays an important role in pacing Earth's climate history, including paleoclimate dynamics, and its imprint can be seen in various geoarchives. Its signature is often evident through typical rhythmic patterns in sediments. The detailed study of those patterns led to a better understanding of orbital climate forcing, while also providing more precise constraints on the geological time scale. Due to the tidal evolution in the Earth-Moon system, the precession and obliquity periods get shorter when going back in time while the main eccentricity 405 kyr period remains stable. While several astrophysical models describe the evolution of the length of precession- and obliquity cycles, few reliable and quantitative geological information from tidalites and astrochronology are available. To better constrain these key astronomical parameters in the distant past, we calculate precession and obliquity properties for the Devonian (∼420-360 million years before present) as reconstructed from a suite of geological datasets. Our results show the period of precession to be 19.4-16.1 kyr, and the dominant p+s3 obliquity period to be 29.50±0.46 long. These findings are compared with and support the presence of oceanic tidal resonances at 300 and 540 Ma, as shown in the recent AstroGeo22 model of the Earth-Moon evolution of (Farhat et al., 2022). • We develop an approach to reconstruct the length of precession in Earth history. • We apply this method to several Devonian datasets and reconstruct precession length. • Data-model comparison of Earth's tidal evolution shows tidal resonances. [ABSTRACT FROM AUTHOR]

The Late Pliensbachian–Early Toarcian is a pivotal time in the Mesozoic era, marked by pronounced carbon-isotope excursions, biotic crises and major climatic and oceanographic changes. Here we present new high-resolution carbon-isotope and magnetic-susceptibility measurements from an expanded hemipelagic Late Pliensbachian–Early Toarcian section from the Middle Atlas Basin (Morocco). Our new astronomical calibration allows the construction of an orbital time scale based on the 100-kyr eccentricity cycle. The Early Toarcian Polymorphum Zone contains 10 to 10.5 repetitions of the 100-kyr eccentricity both in the carbon-isotope and the magnetic-susceptibility data, leading to an average duration of 1.00 ± 0.08 myr. We also show that the Late Pliensbachian–Early Toarcian global carbon-cycle perturbation has an average duration of 0.24 ± 0.02 myr. These durations are comparable to previous astrochronological time scales provided for this time interval in the most complete sections of the Tethyan area, and longer than what has been provided in condensed sections. Anchoring this framework on published radiometric ages and astrochronological time scales, we estimate that the carbon-cycle perturbation of the Late Pliensbachian–Early Toarcian corresponds with the early phase of the Karoo and Chonke Aike large igneous provinces. Likewise, our new age constraints confirm that the Toarcian oceanic anoxic event is synchronous to the main phase of the Ferrar volcanic activity. Thus, these successive and short phases of the volcanic activity may have been at the origin of the successive phases of the mass extinctions observed in marine biotas in the Pliensbachian and Toarcian times. [ABSTRACT FROM AUTHOR]

The geologic record of Milankovitch climate cycles provides a rich conceptual and temporal framework for evaluating Earth system evolution, bestowing a sharp lens through which to view our planet's history. However, the utility of these cycles for constraining the early Earth system is hindered by seemingly insurmountable uncertainties in our knowledge of solar system behavior (including Earth-Moon history), and poor temporal control for validation of cycle periods (e.g., from radioisotopic dates). Here we address these problems using a Bayesian inversion approach to quantitatively link astronomical theory with geologic observation, allowing a reconstruction of Proterozoic astronomical cycles, fundamental frequencies of the solar system, the precession constant, and the underlying geologic timescale, directly from stratigraphic data. Application of the approach to 1.4-billion-year-old rhythmites indicates a precession constant of 85.79 ± 2.72 arcsec/year (2σ), an Earth-Moon distance of 340,900 ± 2,600 km (2σ), and length of day of 18.68 ± 0.25 hours (2σ), with dominant climatic precession cycles of ~14 ky and eccentricity cycles of ~131 ky. The results confirm reduced tidal dissipation in the Proterozoic. A complementary analysis of Eocene rhythmites (~55 Ma) illustrates how the approach offers a means to map out ancient solar system behavior and Earth-Moon history using the geologic archive. The method also provides robust quantitative uncertainties on the eccentricity and climatic precession periods, and derived astronomical timescales. As a consequence, the temporal resolution of ancient Earth system processes is enhanced, and our knowledge of early solar system dynamics is greatly improved. [ABSTRACT FROM AUTHOR]

The Newark–Hartford astrochronostratigraphic polarity timescale (APTS) was developed using a theoretically constant 405-kiloyear eccentricity cycle linked to gravitational interactions with Jupiter–Venus as a tuning target and provides a major timing calibration for about 30 million years of Late Triassic and earliest Jurassic time. While the 405-ky cycle is both unimodal and the most metronomic of the major orbital cycles thought to pace Earth’s climate in numerical solutions, there has been little empirical confirmation of that behavior, especially back before the limits of orbital solutions at about 50 million years before present. Moreover, the APTS is anchored only at its younger end by U–Pb zircon dates at 201.6 million years before present and could even be missing a number of 405-ky cycles. To test the validity of the dangling APTS and orbital periodicities, we recovered a diagnostic magnetic polarity sequence in the volcaniclastic-bearing Chinle Formation in a scientific drill core fromPetrified Forest National Park (Arizona) that provides an unambiguous correlation to the APTS. New high precision U–Pb detrital zircon dates from the core are indistinguishable from ages predicted by the APTS back to 215million years before present. The agreement shows that the APTS is continuous and supports a stable 405-kiloyear cycle well beyond theoretical solutions. The validated Newark–Hartford APTS can be used as a robust framework to help differentiate provinciality from global temporal patterns in the ecological rise of early dinosaurs in the Late Triassic, amongst other problems. [ABSTRACT FROM AUTHOR]

We present here a companions study dealing with the chemostratigraphy, palaeocology, chronostratigraphy and palaeoclimate of the upper Barremian-lower Aptian in the Mt. Faito section that build on our earlier work on the Apennine Carbonate Platform (ApCP, southern Italy). The high-resolution correlation of the Mt. Faito record with the cyclostratigraphically and chemostratigraphically tuned Mt. Raggeto reference section of the APCP has provided crucial evidence to reappraise previous views of a substantial stratigraphic continuity in the lower Aptian of the region. Combining δ 13 C, δ 18 O, palaeoecologic and petrographic data herein with available sedimentologic and biostratigraphic information together with reappraised cyclostratigraphic and astrochronologic analyses for the Mt. Faito section, we document substantial gaps throughout the lower Aptian. The timing of two major unconformities, with duration of 1.43 and 4.94 ± 0.10 Ma, as well as the fidelity and completeness of the stratigraphic record have been established using precession (20 ka), short- (100 ka) and long- (400 ka) eccentricity geochronometers. The adopted high-resolution event stratigraphy (HIRES) anchored to the 2012 Geological Time Scale, has provided further valuable insights for assessing the timing and pace of the observed biofacies and chemostratigraphic changes as well as achieving a highly resolved chronostratigraphic framework of the ApCP record for very detailed regional to supra-regional early Aptian correlations. Our analysis at Mt. Faito encompasses 7.5 ± 0.1 Ma ranging from the latest Barremian to the early late Aptian (Unit A to basal Unit D) and demonstrates that only 15% of the investigated time yields rock record. Two missing intervals, including most of the Selli Level Equivalent (SLE), span the late C2-early C5, and the late C5–C8 p.p. isotope segments. These gaps are interpreted as the erosive and/or non-depositional effects of glacioeustatic sea level falls linked to main global scale cooling episodes prior to (125.6 Ma), during (∼124.6 Ma) and after (123.0 Ma) OAE1a, which appear to be linked with the onset of overall humid climate conditions. The transition from a chlorozoan, “Urgonian”-like carbonate factory (C1–C2 p.p. isotopic segments) to the “warm-water” foramol of the greenhouse Crisis Interval (CI) (middle C2 isotopic segment) and, finally, to the waxing and waning of “temperate-water” foramol and microbial productivity mode interludes (middle C5 isotopic segment) are interpreted as the response of the early Aptian neritic ecosystem of the ApCP to the global-scale palaeoceanographic and palaeoclimatic changes driving the OAE1a. The stratigraphic implications of the icehouse interludes in the greenhouse early Aptian are discussed. [ABSTRACT FROM AUTHOR]

Orbitally-induced cycles build stratigraphic sequences on time spans ranging from several thousand to several million years by altering depositional conditions. Previous works have shown that the gas-bearing Faraghan Formation (Cisuralian) has been impacted by orbitally-forced climatic change, resulting in the development of sedimentary sequences on astronomical cycle timescales. Obliquity evolution has been observed in the Faraghan Formation, with ∼1.2 Ma and ∼173 ka modulation cyclicities recorded. We attribute a strong sedimentary noise observed in the Faraghan Formation, which is distinct from the other noises, to a transregional sea-level rise, most likely correspond to MFS P10. The prolific gas zones (PGZ) in the Faraghan Formation are in consistent relationship with obliquity maxima and depositional noise events, which are associated with high obliquity power. This constant offers the hypothesis that obliquity altered the sedimentary regime in such a way that favorable conditions for reservoir quality development occurred. The ∼173 ka obliquity modulation cycle is recorded from the Late Paleozoic. It is postulated that this periodicity was the causal mechanism for the creating of the Faraghan Formation's fifth-order sequences. The reconstructed sea-level patterns from sedimentary noise modeling (DYNOT) confirm the three third-order sequences proposed for the Faraghan Formation by displaying three different sedimentary noises. The detected ∼1.2 Ma obliquity modulation cycles match the ∼1.2 Ma periodicities filtered from the DYNOT median values, indicating that the ∼1.2 Ma orbital cycle is one of the primary drivers of regional sea level. ∼1.2 Ma obliquity modulation cycles are correlated with third-order sequences, implying that the aforementioned cycle was one of the key mechanisms causing the creation of these third-order sequences. • The ∼173 ka obliquity modulation cycle was recorded from the Paleozoic. • The prolific gas zones in the Faraghan Formation correlate to the obliquity maxima and depositional noise events. • The ∼1.2 Ma obliquity modulation cycles are consistent with third-order sequences. • Regional sea level was reconstructed using sedimentary noise patterns. [ABSTRACT FROM AUTHOR]

Numerous borehole logging datasets gathered for commercial and scientific purposes are available around the globe. However, studies valorising the chronostratigraphic potential of these datasets through time series analyses remain sparse despite the excellent completeness of downhole logging data retrieved in a fast and high-resolution fashion. The major reason for this is the complexity of such approaches and potential pitfalls that may discourage non-experienced users. Here we provide an overview that summarizes the most relevant properties of borehole logging measurements for time series analysis and cyclostratigraphy. Further, we provide a brief introduction of most relevant time series analyses methods, including several examples of borehole logging cyclostratigraphy. Compared to analyses and interpretations of data from cores or exposures, it is important to be aware of borehole logging data specific pitfalls. These include environmental corrections like the effect of variation in borehole diameter, the effects of drilling fluids, and that presented logs may consist of merged results logged in several depth sections. [ABSTRACT FROM AUTHOR]

Accurate age control of the late Tortonian to early Messinian (8.3–6.0 Ma) is essential to ascertain the origin of benthic foraminiferal δ 18 O trends and the late Miocene carbon isotope shift (LMCIS), and to examine temporal relationships between the deep-sea, terrasphere and cryosphere. The current Tortonian–Messinian Geological Time Scale (GTS2012) is based on astronomically calibrated Mediterranean sections; however, no comparable non-Mediterranean stratigraphies exist for 8–6 Ma suitable for testing the GTS2012. Here, we present the first high-resolution, astronomically tuned benthic stable isotope stratigraphy (1.5 kyr resolution) and magnetostratigraphy from a single deep-sea location (IODP Site U1337, equatorial Pacific Ocean), which provides unprecedented insight into climate evolution from 8.3–6.0 Ma. The astronomically calibrated magnetostratigraphy provides robust ages, which differ by 2–50 kyr relative to the GTS2012 for polarity Chrons C3An.1n to C4r.1r, and eliminates the exceptionally high South Atlantic spreading rates based on the GTS2012 during Chron C3Bn. We show that the LMCIS was globally synchronous within 2 kyr, and provide astronomically calibrated ages anchored to the GPTS for its onset (7.537 Ma; 50% from base Chron C4n.1n) and termination (6.727 Ma; 11% from base Chron C3An.2n), confirming that the terrestrial C3:C4 shift could not have driven the LMCIS. The benthic records show that the transition into the 41-kyr world, when obliquity strongly influenced climate variability, already occurred at 7.7 Ma and further strengthened at 6.4 Ma. Previously unseen, distinctive, asymmetric saw-tooth patterns in benthic δ 18 O imply that high-latitude forcing played an important role in late Miocene climate dynamics from 7.7–6.9 Ma. This new integrated deep-sea stratigraphy from Site U1337 can act as a new stable isotope and magnetic polarity reference section for the 8.3–6.0 Ma interval. [ABSTRACT FROM AUTHOR]

In this study, we report a tuned astronomical time scale for a sedimentary formation in Early Cretaceous – the lower Linze Section located in the Zhangye Basin of the central Hexi Corridor, northwestern China. Based on detailed field investigations, we identified this sediment as the Xiagou Formation, which is widely distributed in the region. A thick, prominent limestone layer crops out in the middle portion of the Linze Section, and can be correlated to a similar limestone layer in the Liupanshan Group, which has been dated via high-resolution magnetostratigraphy. This correlation places an age constraint of around 114 Ma for the top of the underlying strata. A total of 1245 samples were collected from the 474-m-thick lower Linze Section, for magnetic susceptibility measurements and cyclostratigraphic analysis. Spectral and continuous wavelet analyses were applied to the low-frequency magnetic susceptibility series and the percentage frequency-dependent magnetic susceptibility series, as well as to specific subsections exhibiting visible rhythmic bedding. A hierarchy of sedimentary cycles was identified, with wavelengths of 21.5–37.0 m, 7.5–9.5 m, 2.1–4.4 m, and 1.4–1.7 m. The ratios between these lengths correspond well to the ratios between the durations of Earth's orbital long-eccentricity, short-eccentricity, obliquity, and precession cycles. We interpret these sedimentary cycles to reflect the effects of orbital forcing on sedimentary processes. Using band-pass filtering to specifically extract eccentricity cycles, we established a tuned astronomical time scale for the Xiagou Formation in the lower Linze Section, with a total duration of about 6.1 Myr (114.1 Ma to 120.2 Ma). Based on this timescale, the sedimentation rate of the Xiagou Formation is estimated to be in the range of 62–105 m/Myr, with most intervals yielding rates in the 70–80 m/Myr range. [ABSTRACT FROM AUTHOR]

We present measurements of radiocarbon in annual tree rings from the time period 980-1006 Common Era (C.E.), hereby covering the cosmic ray event in 994 C.E. The new radiocarbon record from Danish oak is based on both earlywood and latewood fractions of the tree rings, which makes it possible to study seasonal variations in 14C production. The measurements show a rapid increase of ∼10‰ from 993 to 994 C.E. in latewood, followed by a modest decline and relatively high values over the ensuing ∼10 years. This rapid increase occurs from 994 to 995 C.E. in earlywood, suggesting that the cosmic ray event most likely occurred during the period between April and June 994 C.E. Our new record from Danish oak shows strong agreement with existing Δ14C records from Japan, thus supporting the hypothesis that the 994 C.E. cosmic ray event was uniform throughout the Northern Hemisphere and therefore can be used as an astrochronological tie point to anchor floating chronologies of ancient history. [ABSTRACT FROM AUTHOR]

The Aptian stage, between ∼113 and ∼121 million years ago (Ma), was punctuated by a succession of Oceanic Anoxic Events (OAEs), recording extreme global warmings, dramatic expansions of the ocean's oxygen minimum zones, along with perturbations to the biotic and carbon cycles. However, the chronology of the Aptian stage is poorly constrained, impacting the duration and timing of OAEs. Using a greatly expanded sedimentary composite record (380 m) of key outcropping sections in the Vocontian Basin (SE France) combined with available radiometric dates and correlations to a set of astronomical solutions, we provide a constrained absolute astrochronology of the Aptian stage. The 405 kyr (g Venus –g Jupiter) eccentricity astronomical timescale indicates a minimal duration of ∼9.4 Myr for the Aptian stage and an age of 122.6 ± 0.3 Ma for the base of the Aptian, consistent with radioisotope dating. We find a deviation in the periodicity of g Mercury –g Jupiter eccentricity term in the mid-Aptian stage, at ca. 117.19 ± 0.3 Ma, that we ascribe as an expression of the resonance transition σ = (g Mercury – g Jupiter) – (s Mercury – s Venus), in relation with a strong chaotic orbital motion of Mercury. Such a geological observation is supported by a concomitant resonant transition in the La2004 astronomical model. • The tuned MS data indicates a minimal duration of ∼9.4 Myr for the Aptian stage. • Our revised Aptian duration appears concordant with numerical calibration. • A shift in the g Mercury –g Jupiter eccentricity term is observed at 117.19 ± 0.3 Ma. • Geological observation is supported by a resonant transition in astronomical model. [ABSTRACT FROM AUTHOR]

High temporal resolution is of paramount importance in stratigraphic studies of major events in earth history such as the end-Triassic extinction (ETE). Although it ranks among the most severe Phanerozoic mass extinctions, the precise timing and duration of the cascade of environmental and biotic changes across the Triassic-Jurassic boundary (TJB) interval remains controversial. Here we present a cyclostratigraphic study of the Csővár section (Hungary), a continuous carbonate succession from an intraplatform basin that yielded significant geochemical and paleontological data from around the TJB. We analyzed ten elemental time series and stable isotope data series and detected cyclicities with periodicities similar to the orbital cycles of the ∼405 kyr long and ∼124 kyr short eccentricity, the ∼34 kyr obliquity, and the ∼17–21 kyr precession. The astrochronologic age model suggests that the ∼52 m thick section was deposited in 2.9–3 Myr, with an average sedimentation rate of 1.73–1.79 cm/kyr. We establish that the section contains the last ∼1.3 million years of the Rhaetian and most of the Hettangian, supporting a <2 Myr duration for this stage. The duration of the initial carbon isotope anomaly (ICIE) is estimated at ∼40–80 kyr. Previously recognised meter-scale sequences are in agreement with the long eccentricity cycles up to the level of the ICIE but subsequently this relationship becomes less clear, possibly reflecting the effects of the end-Triassic climatic/environmental perturbations and associated changes in the depositional environment superimposed onto overarching astronomical forcing. We propose a cyclicity-based environmental model for sedimentation in the Csővár basin where the observed antiphase behaviour of the carbonate accumulation and the terrigenous input and dissolved silica was driven by a combination of aquifer- and limno-eustasy and the ˝megamonsoon˝ system that dominated the climate of the peri-Tethyan realm. This study highlights that intraplatform carbonate successions can be suitable archives to preserve orbital cyclicities and the new astrochronological age model helps improve our understanding of the ETE and other events in the TJB interval. • Orbital signal in elemental and isotopic time series from intraplatform carbonates. • Astrochronologic age model of a continuous marine Triassic-Jurassic boundary section. • Time constraints on records of end-Triassic extinction and environmental change. • Cyclostratigraphy-based depositional model and sequence stratigraphic interpretation. • Effective orbital forcing of aquifer- and limnoeustasy under „megamonsoon" climate. [ABSTRACT FROM AUTHOR]

Episodes of Environmental Change (EECs) were times of accelerated hydrological cycle that punctuated the Early Cretaceous. Uncertainties in the geologic time scales however preclude full understanding of the onset, unfolding, and termination of EECs. Here, we reanalyze the hemipelagic sedimentary series from France and Spain from the Valanginian to the Barremian to provide a comprehensive and accurate time scale of the Valanginian–Barremian interval based on the stable 405-kyr eccentricity cycle. According to our astrochonologic framework, the Weissert Event started 134.56 ± 0.19 Ma, in perfect synchronicity with the peak of volcanic activity of the Paraná-Etendeka Large Igneous Province. On average, EECs show a pacing of 2.40 Myr from the Valanginian to the Barremian, in phase with detrital supply and carbon isotope variations from marine carbonates. Long eccentricity cycles were hence key parameters in the regulation of climate and carbon cycles in the Early Cretaceous through changes in the detrital and nutrient supply, oceanic fertilization, organic carbon storage and global sea level. A long obliquity forcing, at 1.2 Myr, is also observed through the studied interval in both the detrital and carbon-isotope ratios series, allowing the identification of long isotopic stages in the Early Cretaceous. Our study highlights a positive correlation between continental runoff and sea-level change, suggesting that glacio-eustasy, and not aquifer-eustasy, was the main driver of global-sea level fluctuations during the Early Cretaceous. We also demonstrate that the humid peak related to the Weissert Event is driven by the pacing of the long orbital cycles despite the emplacement of the Paraná-Etendeka province. Nevertheless, in comparison to other EECs of the Valanginian–Barremian, the Weissert Event appears as a singularly long event with stronger impact on climate and marine ecosystems compared to other EECs. We posit that this is a consequence of the concomitant effect of the emplacement of the Paraná-Etendeka province and the long orbital cycles. [Display omitted] • New time scale proposed from the Valanginian to the Barremian. • Onset of the Weissert Event synchronous to the Paraná-Etendeka Large Igneous Province. • Control of long obliquity and eccentricity on detrital and carbon cycles. [ABSTRACT FROM AUTHOR]