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The lower Maeotian sedimentary rocks of the Popov Kamen section (Russia, Taman Region, Eastern Paratethys) were investigated by cyclostratigraphy methods based on magnetic susceptibility measurements. Time series analysis (Lomb–Scargle and REDFIT periodograms, wavelets, Gaussian filters) revealed statistically significant signals with 5.2–6.0 m wavelength corresponding most likely to the 41,000-year obliquity cycle. These new data imply a duration of the early Maeotian regional substage of 0.9 Myr, and this sets the age of the Sarmatian–Maeotian boundary to about ~ 7.6 Ma. These astronomically tuned lower Maeotian sediments of the Popov Kamen section result in an average sedimentation rate of about 11–12 cm/kyr (= 90.9–83.3 yr/cm) for the whole section. In the relatively deep-water setting of the lower Maeotian Popov Kamen section, no major hiatuses were detected, with the exception of an insignificant gap in the upper part of the successions. The marine transgression in the Eastern Paratethys at the beginning of Maeotian was probably caused by the opening and consequent deepening of Rifian Corridor. At the end of the Tortonian (~ 7.6 Ma), this tectonic event terminated the restricted conditions in the Mediterranean and re-established the connection between the Mediterranean Sea and Paratethys. Therefore, the Tortonian–Messinian transition in the Mediterranean probably corresponds to the clays of the lower part of the lower Maeotian record in Paratethys, which is located above the first bryozoan build-ups and below the 1.8 m thick diatomite bed in the Popov Kamen section. Our astronomically calculated age for the beginning of the Maeotian at ~ 7.6 Ma strengthens the connection between these two transgressive events. [ABSTRACT FROM AUTHOR]

Early Cambrian Qiongzhusi Formation has attracted great attention due to shale gas finding. However, this organic-rich shale formation is yet no robust high-resolution stratigraphic sequence framework. Here the evidence on Milankovitch cycles in three wells drilled through Qiongzhusi (QZS) Formation in Sichuan Basin has been reported. The logging data made it possible to develop a floating timeline calibrated to stable eccentricity cycles of 405-kyr within ~10.92 and ~7.34 Myr intervals in intracratonic rift and low bulge of Sichuan Basin, respectively. In this research, astronomical time scale was anchored to the U Pb Zircon age of QZS Formation/Maidiping Formation boundary (526.86 ± 0.16 Ma), developing an absolute timescale for considered intervals extending from 526.86 to 515.94 Ma. Average spectral misfit and correlation coefficient analyses were applied to quantitatively measure the fitting of the witnessed sedimentary cycles to astronomical periods and provide a possible sedimentation rate range. A sedimentary noise model was chosen to detect high-resolution sea-level variations under the control of orbital forcing and variations of sea-level were linked to obliquity modulation cycles of about 1.2 Myr. The orbital obliquity modulation cycles witnessed for early Cambrian QZS Formation (~1.2 Myr) were correlated to eustatic variations of sea level generated based on sedimentary noise model (DYNOT and ρ1). Furthermore, correlations between sequence stratigraphy and cyclostratigraphy were discussed, and the third-order sequence boundaries well corresponded to minima ~1.2 Myr orbital obliquity modulation curve and high values of DYNOT. The previous sequences framework was demonstrated to be isochronous and credible. • Orbtial cyclicity has been detected by time series method using the K channel of GR logs in shale sequence. • Floating and absolute Astronomical Time Scales have been established for the Qiongzhusi Formation in the Sichuan Basin. • Reconstruct the sea-level changes by using DYNOT simulation approach. • ∼1.2-Myr amplitude modulation of obliquity dominated sea-level change. [ABSTRACT FROM AUTHOR]

The 700-m-thick Hauterivian to Albian section from the interior of the large, Adriatic Platform is exposed on Mljet and Korčula islands, Croatia. The cyclic platform consists of meter-scale parasequences, bundled into parasequence sets, superbundles and then into breccia-bounded depositional sequences. Spectral analysis of time series (cycle number vs. cycle thickness) shows peaks in the short-term eccentricity (95 to 130 kyr) bands and 160 to 200 kyr bands. Isotope samples from micrite matrix of mudstone and wackestone have δ 13 C values generally from −1.5 to +2‰ VPDB, and δ 18 O from −1 to −3.5‰ VPDB. Adriatic Platform δ 13 C values are shifted ~2‰ VPDB more negative than marine pelagic values. A δ 13 C and δ 18 O meteoric signal is limited to just beneath sequence boundaries, suggesting that the isotopic shift is due mainly to marine phreatic‐ and synorogenic burial diagenesis. Major excursions on the 5-point smoothed δ 13 C profile of the Adriatic Platform, tied biostratigraphically to δ 13 C curves from pelagic sections, include the oceanic anoxic events OAE1a, 1b, and 1c. Time series constructed from δ 13 C values (unsmoothed data) vs. stratigraphic position show peaks in the Milankovitch band, especially short-term eccentricity. Most positive peaks are near parasequence set boundaries (50 to 60%) and regressive parts of parasequences (20%). Although diagenetically shifted, the δ 13 C record retains a highly clipped memory of astronomically-driven global δ 13 C fluctuations albeit modified by platform water restriction during cyclic deposition. [ABSTRACT FROM AUTHOR]

The Paleogene coal-bearing deposits (Pinghu Formation) of the Xihu Depression form the most productive hydrocarbon source in the East China Sea Shelf Basin. Due to the lack of reliable magnetostratigraphic, paleontologic and geochemical/isotope data, these source rocks are still poorly dated. The absence of a robust time frame results in many disputes on the age and duration of the Pinghu Formation and hampers a thorough understanding of its sedimentary evolution. Here, we study the cyclic changes in the depositional environment that can be retrieved from seismic interpretation and sequence stratigraphic analyses of well log data (e.g., stacking patterns, logging, and lithofacies changes). We recognize one second-order sequence, three third-order sequences and 12 fourth-order parasequences. Next, we construct a floating astronomical time scale by using power spectra and evolutionary fast Fourier transformation analysis on the gamma-ray data. Wavelength variations in the gamma-ray spectra show similar ratios as the astronomically-forced Milankovitch cycles (i.e., eccentricity, obliquity and precession). The filtered long and short orbital eccentricity cycles show a good match with the La2010d astronomical target curve, allowing to create an independent time frame based on cyclostratigraphy. Our floating astronomical time scale provides new numerical age constraints for the Pinghu Formation, resulting in a total duration of ~4.95 Myr. A re-analysis of the available age data indicates that the sequence stratigraphic framework of the Pinghu Formation is best constrained to the early Oligocene, instead of the previously assumed late Eocene. Our study highlights that astronomical interpretation of sequence stratigraphic analyses is an excellent method to estimate the duration of sedimentary successions in boreholes and adds to a better understanding of the temporal and spatial sediment distribution patterns in the East China Sea Shelf Basin. • Astronomical forcing of the deposits of the East China Sea Shelf Basin is studied. • Hydrocarbon source rocks of the Pinghu Formation show a sedimentary cyclicity. • Cyclostratigraphic analysis on gamma-ray series reveals Milankovitch cycles. • Astronomical interpretation of sequences provides the duration of sedimentary units. • The Eocene or Oligocene Pinghu Formation spans at least 4.95 Myr. [ABSTRACT FROM AUTHOR]

We propose a high-resolution regional to global scale correlation of two Hauterivian/Barremian shallow water carbonate platform sections belonging to different palaeogeographic domains of the Southern margin of the Tethys. These successions are now located more than 500 km apart and are represented by 137 m of core drilled at Monte Raggeto (southern Apennines, Italy) and by 80 m of well stratified rocks cropping out in the Podgorica Mountains (Dinarides, Montenegro). They display three superimposed orders of stratigraphic cyclicity defined by elementary cycles grouped into bundles and superbundles and attributed to orbitally induced composite sea-level fluctuations. Elementary cycles are interpreted as the precession and the obliquity periodicities (≅20–40 ky), while bundles and superbundles correspond to the short (≅100 ky) and long (≅400 ky) eccentricity cycles, respectively. As both the ratios between the elementary cycles and the bundles and between the bundles and the superbundles do not always reflect the classical 5:1 and 4:1 relationship, the sedimentary record of both the studied sections is likely to include omission of bundles or their portion.The general evolution of depositional and diagenetic facies, the vertical change in thickness of the cyclic units, and the interpretation of superbundles as small-scale depositional sequences, suggest that elementary cycles and their groups are superimposed on lower-frequency environmental oscillations. These display an upward Transgressive/Regressive Trend (T/RT) of the facies and testify to larger-scale variations of accommodation potential on the shelf.T/RTs, sequence stratigraphic interpretation of the superbundles as well as the common occurrence of the biostratigraphic dated Hauterivian/Barremian boundary in the studied sections, support the long-distance regional correlation between the successions to be carried out on the 100 ky scale. Moreover, by assuming the maximum flooding intervals of time-equivalent superbundles as virtually isochronous intervals, we have detected stratigraphic gaps of 1200 and 600 ky in the Monte Raggeto and in the Podgorica Mountains sections, respectively. Both sections are formed of 10 complete superbundles each of them testifying to the 400-ky-long eccentricity. Hence, the Monte Raggeto and Podgorica Mountains successions represent a duration of at least 4.0 My in terms of elapsed time, regardless of gaps within the stratigraphic record.Finally, a correlation between the orbitally induced compared sections and both the 3rd order Tethyan stratigraphic cycles and the global cycle chart is suggested.Our study confirms that cyclically organized, shallow marine carbonate platform deposits controlled by orbitally induced sea-level fluctuations represent a powerful tool for high-precision regional and global correlations. This can be of fundamental importance for quantification of sedimentary, diagenetic, and evolutionary processes as well as for the understanding of autocyclic versus allocyclic control on sequence development. [Copyright &y& Elsevier]

Abstract: High-resolution magnetic susceptibility (MS) analysis was carried out on a Lower Kimmeridgian alternating marl–limestone succession of pelagic origin that crops out at La Méouge (Vocontian Basin, southeastern France). The aim of the study was to characterize the strong, dm-scale sedimentary cyclicity of the succession at a very high resolution, and to analyze the cycles for evidence of astronomical forcing. From marl to limestone, MS varies progressively and closely tracks the highest frequency cyclicity corresponding to the basic marl–limestone couplets. Long-term wavelength cycling modulates the high-frequency cyclicity (couplets), and appears to be controlled by clay content. Spectral analysis of the MS record reveals the presence of the complete suite of orbital frequencies in the precession, obliquity, and eccentricity (95–128 ka and 405 ka) bands with very high amplitude of the precession index cycles originating from dm-scale couplets. 405 ka-eccentricity cycles are very pronounced in the MS maxima of the marl members of the couplets, suggesting eccentricity-driven detrital input to the basin. 405 ka-orbital tuning of the MS maxima further sharpens all of the orbital frequencies present in the succession. These results are similar to those of previous studies at La Méouge that used carbonate content observed in field. Our results are also in accordance with cyclostratigraphic studies in Spain and Canada that report dominant precession index forcing. By contrast, in the Kimmeridge Clay (Dorset, UK), obliquity forcing dominates cyclic sedimentation, with weaker influence from the precession index. Ammonite zone duration estimates are made by counting the interpreted precession cycles, and provide an ultra-high resolution assessment of geologic time. In sum, this study demonstrates the power of the MS as a proxy in characterizing the high-resolution cyclostratigraphy of Mesozoic sections, particularly in alternating marl–limestone successions, and for high-resolution correlation and astronomical calibration of the geologic time scale. [Copyright &y& Elsevier]

The Jurassic-Cretaceous transition was marked by the fragmentation of the West Gondwana supercontinent and consequent opening of the Atlantic Ocean. This event resulted in extensive lava flows in the central portion of West Gondwana, composing the Central Atlantic Magmatic Province. In the Parnaíba Basin (NE Brazil), a large lacustrine system succeeded this event; nevertheless, the post-CAMP scenario and the influence of the decreasing isotherms in the Mesozoic sedimentation are poorly understood. In this sense, cyclostratigraphy and outcrop-based facies analysis were carried out in the lacustrine stratigraphic record, allowing the recognition of four paleoenvironments: central lake, sheet-like delta front, lakeshore and ephemeral fluvial channels, mainly organized in shallowing upward cycles. The upsection transition of thin black shales and limestones to thick oxidized mudstones and stratified sandstones reflects the evolution of underfilled to overfilled lake settings. The lacustrine succession is organized in four major depositional cycles, characterized by millimeter to centimeter-scale cycles, bounded by unconformities or flooding surfaces. The cycles define a retrogradational-progradational-retrogradational stacking pattern, with random and frequent changes in lithology and cycle thickness. Cyclostratigraphic data suggest that the upward increasing accommodation space was controlled by the post-CAMP thermal subsidence, as well as shifts in sedimentary supply and water inflow/outflow. The time span of this subsidence phase lasted from even before the CAMP magmatism (~200 Ma), affecting the whole deposition of the lacustrine succession, and was interrupted by the Cretaceous magmatic event (~126 Ma). Subsidence was also enhanced by crustal loading associated with thick subsurface Jurassic intrusions and probably influenced the whole basin, in consequence of flexural effects. • A lacustrine depositional system is defined by cyclostratigraphy and facies analysis. • Facies are mainly organized in shallowing upward cycles. • The lacustrine succession evolves from an underfilled to an overfilled lake system. • The cycles define increasing accommodation space upsection. • Geological and geophysical data suggest a post-CAMP thermal subsidence. [ABSTRACT FROM AUTHOR]

Metre-scale sequences may result from the combined effects of allocyclic and autocyclic processes which are closely inter-related. The carbonate ramp that developed northwest of the Iberian Basin during the late Kimmeridgian was affected by northwestward migrating cyclones. Marl–limestone alternations that settled in mid-ramp environments contain abundant mm to cm thick coarse-grained accumulations that have been related to these events. The aim of this paper is to determine the impact of storm-induced processes on the metre-scale sequence features. Four sections (R3, R4, R6, and R7), which are 5 to 7 m in thickness, were studied bed-by-bed along a 4 km-long outcrop, which shows the transition between the shallow and the relatively deep realms of the middle ramp. Metre-scale sequences were defined and correlated along this outcrop according to the detailed microfacies analysis of host, fine-grained deposits, palynofacies and sequence-stratigraphic analyses, and carbon- and oxygen-isotope measurements. The evolution through time of sedimentary features such as the size of quartz grains and the relative abundance of grains other than quartz (i.e., muscovite, bivalve, ooid, and intraclast) does not correlate from one section to the other, suggesting that the finest as well as the coarsest sediment was reworked in these storm-dominated environments. Small- and medium-scale sequences are defined according to changes in alternation, marly interbed, and limestone bed thickness, and correlated from one section to the other. Because of the effects of storms on sediment distribution and preservation, sequence boundaries coincide with thin alternations and marly interbeds in the most proximal sections (i.e., R3, R4), while they correspond to thin alternations and limestone beds in the most distal sections (i.e., R6, R7). Field observations and palynofacies analyses confirm this sequence-stratigraphic analysis. The excursions in carbon- and oxygen-isotope values are consistent with the lithological correlations, but in themselves are not conclusive. Marl–limestone alternations, and small-, and medium-scale sequences are hierarchically stacked, suggesting an orbital control on sedimentation with alternations lasting 20 kyr, small-scale sequences, 100 kyr, and medium-scale sequences, 400 kyr. As biostratigraphic analyses and spectral analysis are not the most appropriate tools to validate this time calibration in such a short interval and highly dynamic system, an alternative approach is developed, which is based on the quantification of the rates of sediment accumulation, preservation, and sea-level rise. [ABSTRACT FROM AUTHOR]

Peritidal carbonate-evaporite successions, since they are developed in the transition between continental and marine realms, provide essential keys for palaeobathymetric and palaeoclimatic interpretations. As a result, several facies models have been proposed to assist on the interpretation of ancient tidal flat deposits, and peritidal successions have been extensively used for cyclicity analyses. In this study, well-exposed, Lower Cretaceous peritidal deposits (Oncala Group, Cameros Basin, N Spain) are analysed and compared with the most commonly-used present-day analogues (from Shark Bay, the Arabian Gulf and the Bahamas) and with ancient peritidal successions, providing their palaeoenvironmental and palaeoclimatic interpretation, assessing the usefulness and limitations of the facies models, and evaluating the suitability of these deposits for analysis of decimetre to metre-scale cycles. The studied peritidal deposits consist of thinly-bedded to laminated dolostones, dolomitic stromatolites, stromatolite breccias, flat-pebble and edgewise breccias, and calcite and quartz pseudomorphs after anhydrite nodules. Abundant resemblances of the peritidal deposits of the Oncala Group with those of Shark Bay, including that they are largely composed of microbialites and intraclasts, makes the peritidal deposits of the Oncala Group one of the best fossil analogues of this present-day setting. However, the presence of anhydrite nodules indicates pervasive evaporite precipitation in the supratidal zone, which is a feature that does not occur in supratidal flats of Shark Bay, but is characteristic of arid sabkhas of the Arabian Gulf. Nevertheless, the fact that carbonate-evaporite tidal flats of the Oncala Group were laterally related with siliciclastic tidal flats with large freshwater input and broadly inhabited by dinosaurs, suggests that anhydrites precipitated under less arid climates than those of the Arabian Gulf nowadays, pointing to semiarid climatic conditions during deposition. Moreover, the fact that peritidal deposits with anhydrite nodules were exclusively formed in a low-subsidence area of the Cameros Basin suggests that the rate of accommodation space creation also played an important role in their development. Regarding the comparison with other fossil peritidal sediments, the studied deposits show more abundant similarities with Proterozoic and Cambrian successions, composed mainly of stromatolites, microbial laminites, and intraclasts, than with other Mesozoic peritidal deposits, in which bioclasts and burrowing are usually more abundant. This highlights the difficulties for assigning specific features to certain geological ages. Finally, peritidal facies of the Oncala Group may change laterally and vertically to any other facies, showing a patchy lateral distribution of facies and an unsystematic vertical stacking pattern. The sedimentary features of the stromatolite, breccia and thinly-bedded to laminated dolostone facies do not allow their assignment to a unique tidal zone. Moreover, sedimentary features indicative of subaerial exposure, such as anhydrite nodules formed in the capillary zone, occur within any of the carbonate facies and show limited lateral extent. This results in a succession that cannot be clearly subdivided into subsequent shallowing-upward cycles not even by using erosive surfaces or the anhydrite nodule layers as marker horizons of the upper part of the cycles, because their limited lateral extent prevents reliable correlations. Similar composite lateral and vertical facies relationships have been documented both in the present-day analogues and in ancient successions, which suggests that this kind of facies relationships may be common in peritidal successions and highlights the caution that must be taken when trying to perform cyclicity analysis on them. [ABSTRACT FROM AUTHOR]

The ~125 m thick lower to lowermost upper Sinemurian peritidal to shallow subtidal platform carbonates in the Llevant Mountains of Mallorca (Spain) have been analysed from four stratigraphic sections, to provide new data on the hierarchical stacking pattern of high-frequency depositional sequences. Due to the fact that in shallow water environments the stacking of carbonate facies can be controlled by external (allocyclic) and internal (autocyclic) processes, deciphering the dominant controls on the high-frequency sequence architecture of these platforms is a challenge. The studied carbonates encompass a high variety of facies representative of open lagoon, internal bars, restricted lagoon and tidal flats with local beach sands. Based on a detailed analysis of vertical facies trends and bounding surfaces, large-, medium- and small-scale sequences have been identified within the long-term transgressive-regressive facies cycle defined by the entire succession. Large-scale sequences (~10–30 m thick) and medium-scale sequences (~1–10 m thick) are generally shallowing-upward sequences bounded by sharp facies changes to relatively deeper facies, and have been related to sea-level variations driven by long- (~400 kyr) and short- (~100 kyr) eccentricity cycles respectively. The overprinting of differential subsidence (probably related to extensional tectonic) and carbonate production and accumulation processes varied throughout time, controlling the lateral continuity and preservation potential of the ~100 kyr medium-scale sequences. Shallowing-upward, locally aggradational, small-scale sequences (~0.3 to 5 m thick) are very variable in number and thickness and cannot be correlated between sections, pointing out that their most important controlling factor was the internal processes (hiatuses and erosion related to subaerial exposure at the peritidal caps, lateral migration of internal bars, local wave and currents patterns, depositional and erosional processes related to spring tides and storms) in the frame of a complex mosaic of facies within the studied platform. [ABSTRACT FROM AUTHOR]

The Lower Ordovician mixed carbonate–shale Dumugol Formation of Korea was analysed to compare the stratal thickness and facies proportion of measured and decompacted successions and to assess the effect of compaction on the interpretation of cyclicity. Metre-scale cyclic units (MSUs) in the formation consist in part of outer-shelf shale, distal to intermediate mid-ramp limestone–shale couplets, and proximal mid-ramp lime mudstone facies. A total of 119 MSUs were recognised in the studied section. Thickness reduction was estimated based on petrographic evidence, including compressed to uncompressed burrows, firm- to hardground surfaces and differentially compacted laminae, and supplementary values of decompaction factors taken from the literature. Five oscillatory units in the apparent Fischer plots consist of thickening- to thinning-upward packages composed of shallowing- to deepening-upward MSUs. Similar thickness–facies relationships were observed in the lower two oscillatory units of the decompacted Fischer plots; these units are rich in shale. In contrast, a transition to an antithetic thickness–facies pattern occurs in the following units, with common occurrences of limestone facies. The different thickness–facies relationships in the measured and decompacted Dumugol successions indicate that a large portion of the major controls on the formation of sedimentary cyclicity changed from sediment accumulation rate to relative sea-level fluctuations. Such modification by compaction of the original sediment column appears to have been caused by early cementation in calcareous sediments, which resulted in differential thinning between limestone and shaly deposits. These findings reveal that diagenetic influences on sequence-stratigraphic and cyclostratigraphic interpretations have been underestimated, with consequent potential effects on associated local to regional geodynamic models, particularly for mixed carbonate–siliciclastic successions. • Measured and decompacted cyclic patterns of limestone–shale succession are compared. • Cycle thickness–facies proportion trends antithetically modified by decompaction. • Interpretation of cyclicity formation corrected from sedimentation rate to relative sea level changes • Early cementation affected distinct compactional behaviours of limestone and shale. • Compaction effect crucial for interpretation of greenhouse cyclic carbonate–shale successions [ABSTRACT FROM AUTHOR]

Abstract: Early diagenetic dolomitization is a common feature in cyclic shallow-water carbonates throughout the geologic record. After their generation, dolomites may be subject to dedolomitization (re-calcification of dolomites), e.g. by contact with meteoric water during emersion. These patterns of dolomitization and subsequent dedolomitization frequently play a key role in unravelling the development and history of a carbonate platform. On the basis of excellent outcrops, detailed logging and sampling and integrating sedimentological work, high-resolution sequence stratigraphic interpretations, and isotope analyses (O, C), conceptual models on early diagenetic dolomitization and dedolomitization and their underlying mechanisms were developed for the Upper Jurassic / Lower Cretaceous Jura platform in north-western Switzerland and eastern France. Three different types of early diagenetic dolomites and two types of dedolomites were observed. Each is defined by a distinct petrographic/isotopic signature and a distinct spatial distribution pattern. Different types of dolomites are interpreted to have been formed by different mechanisms, such as shallow seepage reflux, evaporation on tidal flats, and microbially mediated selective dolomitization of burrows. Depending on the type of dolomite, sea water with normal marine to slightly enhanced salinities is proposed as dolomitizing fluid. Based on the data obtained, the main volume of dolomite was precipitated by a reflux mechanism that was switched on and off by high-frequency sea-level changes. It appears, however, that more than one dolomitization mechanism was active (pene)contemporaneously or several processes alternated in time. During early diagenesis, percolating meteoric waters obviously played an important role in the dedolomitization of carbonate rocks that underlie exposure surfaces. Cyclostratigraphic interpretation of the sedimentary succession allows for estimates on the timing of early diagenetic (de)dolomitization. These results are an important step towards a better understanding of the link between high-frequency, probably orbitally forced, sea-level oscillations and early dolomitization under Mesozoic greenhouse conditions. [Copyright &y& Elsevier]

Upper Cretaceous marine sequences in the Gulf Coastal Plain (USA) span the Cretaceous–Paleogene (K–Pg) transition, allowing for detailed studies of one of the most severe extinction events of the Phanerozoic. To improve the temporal resolution of the stratigraphic record that represents environmental change leading up to the K–Pg boundary, we constructed a high-resolution chemostratigraphy and cyclostratigraphy of upper Maastrichtian shallow marine deposits located in the state of Mississippi (USA). Upper Maastrichtian strata in this area consist of alternating decimeter scale chalk and marl rhythmites deposited in a hemipelagic setting. New geochemical proxy records were used to test whether rhythmic sedimentation was driven by Milankovitch cycles. Stable isotopes (δ13C carb , δ18O carb), carbonate content (wt% CaCO 3), and elemental concentrations (Ti, K, Fe) integrated with microfossil and ammonite biostratigraphy reveal astronomical forcing in the studied record. Spectral estimation suggests that rhythmic bedding was associated with climate change driven by precession (~20 kyr). Obliquity signals are also apparent in our analysis, and short eccentricity (~100 kyr) is inferred from amplitude modulation of precession. Studied sections were correlated at the precession scale with the recently tuned K–Pg succession near Morello, Italy which is stratigraphically equivalent to the well-characterized K–Pg sites in Gubbio, Italy (Bottaccione, Contessa Highway). Additionally, carbon isotope records from the study area exhibit large scale trends throughout the latest Maastrichtian, similar to those observed in the Morello and Bottaccione sections. Thus, we show that Milankovitch-scale climatic signals and low-amplitude carbon isotope shifts (<0.5‰) of the late Maastrichtian of the Gulf Coastal Plain are well-preserved and can be correlated globally. • A high-resolution chemostratigraphy was constructed for the Prairie Bluff Chalk. • Milankovitch cycles are preserved in Latest Cretaceous chalks in Mississippi. • Carbon isotope records from the Prairie Bluff Chalk may represent a global signal. [ABSTRACT FROM AUTHOR]

Abstract: Spectral reflectance (SR) is a relatively novel technique which is used as a proxy for organic carbon and siliciclastic input in carbonate sediments, in particular in core research. This study summarizes results from high-resolution outcrop SR logging of a Lower Devonian distal ramp carbonate section of the Barrandian area, Czech Republic. The SR data were correlated with parallel petrophysical and geochemical data with an aim to improving their cyclostratigraphic and event stratigraphic interpretation potential and the gaps SR data can fill. Transgressive–regressive trends, indicated by facies stacking patterns, CaCO3 data and spectral gamma-ray (GRS) logs, are well correlated in the regional context and point to third-order eustatic sea-level fluctuations. Peak regressions of the TR cycles are sensitively marked by CIE L*a*b* parameters and percent reflectance in colour bands. The SR and magnetic susceptibility (MS) data are markedly cyclic on a more detailed scale. Their inferred periods vary between 49.2 and 205kyr indicating that they may have been forced by orbital cycles in the Milankovitch band. The SR and MS cycles are either in phase or out of phase. The latter cycles point to a strong diagenetic forcing of the colour cyclicity. Hematite concentration cycles, inferred from SR signal in the Pragian red hemipelagic carbonates, are interpreted as reflecting changing bottom oxygenation and subsurface redox gradients during early diagenesis. The CIE L* parameter was found to be related to the presence of diagenetic hematite, which indicates that cyclostratigraphic analysis of simple greyscale data can be affected by considerable error due to chromacity. Although the CIE L* parameter is partly correlated with CaCO3 concentrations, the MS data are not, which suggests that the MS signal can be significantly influenced by diagenetic minerals and its cyclostratigraphic interpretation can be potentially misleading. The SR data, backed up by GRS, MS and CaCO3 data indicate that the red colour in the Pragian hemipelagic limestones originated from early diagenetic hematite precipitation under the conditions of an oxygenated ocean floor. This suggests that deep-sea bottom oxygentation may have been in operation during the early Devonian, which is traditionally perceived as a typical greenhouse period. The SR data can be obscured in several m thick zones of elevated CIE L* and other colour changes (“leaching zones”) related to postdepositional alteration along subvertical faults, however, this fault-related telogenic alteration has little influence on the MS signal. The combined use of SR and MS has a synergic effect and can significantly improve the interpretation of their respective cyclic signals, particularly in relation to the diagenetic overprint and possible carriers of the MS. [Copyright &y& Elsevier]

Milankovitch cycles during the Phanerozoic affected paleoclimate, the onset/termination of glacial/interglacial periods, sea-level changes, and thus the distribution of different facies in sedimentary basins. The effects of astronomical forcing have been recorded as astronomical frequency signals in sedimentary sequences through geological history. In this research, for the first time, the signal of Milankovitch cycles and orbital obliquity modulation cycles from the Oligocene–Early Miocene Asmari Formation at one of the oil fields in the Dezful Embayment of the Zagros Basin, Iran, have been identified, through wireline logs. Based on that, ten ~1.2 orbital obliquity modulation cycles have been recognized and correlated with global third-order sequences and δ18O events. The number of cycles during the Oligocene–Early Miocene in the Asmari Formation is equivalent to obliquity of the La2004 orbital solution. Additionally, the optimal sediment accumulation rates, depositional duration of this formation, and foraminiferal biozone durations have been calculated. The result of this study shows that sediment accumulation rates varied in the range 2.9 to 3.2 cm/kyr. The foraminiferal biozones are diachronous in this area. Based on the identified 405 kyr long-eccentricity cycles in the three studied wells, three astronomical time spans of 11.5 Myr, 9.42 Myr, and 9.02 Myr were obtained for the Asmari Formation in Wells A, B, and C, respectively. • For the first time ~1.2 Myr orbital obliquity modulation cycles highlighted in the Oligocene-Early Miocene Asmari Formation of SW Iran. • Ten ~1.2 Myr orbital obliquity modulation cycles, which corresponded to global sea level sequences and δ18O events, and atwenty nine long-eccentricity cycles detected from the Asmari Formation. • The astronomical durations of foraminiferal biozones of the Asmari Formation have been estimated. • The astronomical durations of foraminiferal biozones of the Asmari Formation have been estimated. [ABSTRACT FROM AUTHOR]

This paper deals with the depositional sequences that occur within the uppermost part of the Plio–Pleistocene Periadriatic basin fill in the southern Marche region, central Italy. The succession is an Early Pleistocene, easterly dipping clastic wedge showing an overall shallowing trend from slope clays to shallow-marine and non-marine deposits comprising two major sequences, namely Qmb and Qmc. Analysis has provided new insights into: (i) the nature of sedimentary facies and facies associations occurring within the upper part of Qmb and Qmc; (ii) the gradual contact within Qmb between regressive littoral deposits (RLD) and underlying deep-marine blue clays; (iii) the composite origin of the Emilian surface, which is a widespread erosional unconformity separating Qmb from Qmc; (iv) the cyclothemic pattern of Qmc, composed of downstepping, small-scale depositional sequences; (v) the role played by synsedimentary uplift on the stacking pattern of small-scale sequences and their internal architecture.Up to three small-scale depositional sequences have been recognised within Qmc (Qmc1, Qmc2 and Qmc3). They are up to 50 m thick and defined by previously unrecorded, lower-rank, regionally extensive surfaces. Facies organization indicates that, as a rule, in ascending stratigraphic order each small-scale sequence may includes a distinctive basal unconformity surface that can be traced from incised valleys to associated interfluves, an incised-valley fill, a transgressive surface of marine erosion, a transgressive systems tract, a highstand systems tract, a regressive surface of marine erosion and an attached falling stage systems tract. In proximal positions, the small-scale sequences are dominated by transgressive and highstand systems tracts with incised-valley fills and falling stage systems tracts absent or volumetrically much less significant. In relatively basinward locations, where the regressive surfaces of marine erosion converge with the lower sequence boundary, the falling stage systems tract may represent the entire depositional sequence. High-frequency sequences display a distinctive stacking pattern and form a tectonically induced forced regressive sequence set underlain by a composite, tectonically enhanced regressive surface of marine erosion formed by the lateral connection of lower-rank sequence boundaries. [Copyright &y& Elsevier]

Facies, stratal and spectral analyses of an outer ramp lime mudstone succession (Aguilo´n, north Iberian Ranges, Spain) are presented in this work. The studied succession is Late Kimmeridgian (eudoxus and beckeri zones) in age and comprises the transgressive and highstand deposits of a third-order depositional sequence. A number of higher-order sequences (bundles and sets of bundles) have been identified based on the comparative analysis of the bedding planes. The bundles and sets of bundles show a well-defined stratal pattern. Spectral analysis has provided further independent confirmation of the cyclical nature of the bundles and sets of bundles defined from field analysis.The bundles have variable thickness (from 1 to 2 m) and are formed by up to 10 micritic beds. They have been related to sea-level changes controlled by the orbital precession cycle, affecting the shallow productivity area. A significant amount of the lime mudstones accumulated in outer ramp settings were derived from resedimentation of the shallow carbonate production areas. Many of the bundles show a lower interval with a thinning and fining-up trend, indicating a progressive decrease of the carbonate production (and carbonate export) during periods of high-frequency sea-level rise.The late transgressive and highstand deposits show sets of bundles (groups of five bundles, from 5 to 8 m) probably related to sea-level changes controlled by the short eccentricity cycle. The overall thickness and the stacking pattern observed in the sets of bundles are controlled by the long-term sea-level variation. The sets of bundles located in the late transgressive deposits show thinner micritic beds in their lower or middle part. The sets of bundles found in the highstand deposits are thinner and show a thickening-up and thinning-up trend. On the studied carbonate ramp, during periods of long-term sea-level rise, the overall carbonate production (and carbonate export) is high, although the superposition of the high-frequency sea-level rises may result in episodic flooding and drowning of the shallow ramp areas. During periods of long-term, early highstand of sea level, the overall carbonate production (and carbonate export) is more reduced, but it has maximum peaks during the transgressive (and early highstand) intervals of the high-frequency sea-level cycles. Sedimentation during the long-term sea-level fall (late highstand) was scarce and discontinuous in the outer ramp area, and resulted in the overall thickness reduction of the sets of bundles. [Copyright &y& Elsevier]

The extraction of palaeoenvironmental (palaeoclimatic) signals from the chemical composition of siliciclastic sediments is valuable for the reconstruction of past environments, particularly in continental basins. Here we test novel weathering proxies, which are less sensitive to lithological control than the previously used raw element ratios K/Al, K/Ti, and K/Rb: (1) local enrichment factors of K/Al, Mg/Al, and K/Rb, i.e., the element ratios corrected for grain size- and matrix composition using local background functions (Al/Si, Fe, and Ca as explanatory variables) and ordinary regression and (2) robust regression residuals of those element ratios based on isometric log-ratio coordinates of the most relevant "lithogenic" elements (Ca, Fe, Rb, Si, Zr) in the chemical composition. Chemical weathering proxies can be obtained from departures of chemical composition of sedimentary profiles from relationships with other chemical elements, in particular those with grain-size control. The resulting weathering proxies were examined for the Miocene deposits from the Most Basin, the Czech Republic, which recorded one of the major warm episodes of the Cenozoic time – the Miocene Climatic Optimum. The performance of weathering proxies has been checked by (1) comparison of individual proposed proxies in one drill core HK930, (2) detailed analysis of orbital signals in the relevant compositional functions in HK930; and (3) lateral correlation of three cores HK930, DU7, and DO565 of the same basin. The novel proxies show lateral stability and orbital signatures of short eccentricity, obliquity, and precession, confirming their usefulness in palaeoenvironmental studies. Corrections for grain-size and carbonate contents should help to isolate climatic content from the weathering proxies, although in the studied sediments it weakened the precession component in the orbital signal, as grain-size proxies and other compositional data also carried orbital signals. We propose to consider these proxy ideas in palaeoclimatic reconstructions based on chemical weathering proxies. [ABSTRACT FROM AUTHOR]

Lacustrine settings constitute a unique environment that preserves detailed expressions of allocyclic signals such as those of climate and tectonics. Possible decryption of these signatures stems from careful scrutiny of the sedimentation dynamics (temporary base-level variations), lake-level fluctuations (accommodation), and resulting strata bounding surfaces that are used to build a conventional sequence stratigraphic framework. However, due to discrepancies between marine, to which this approach has been initially dedicated, and lacustrine settings (especially regarding the physical scale), deciphering climate from tectonic forcing becomes unwieldy in such interior basins. The present work deals with this challenge and provides insights from a case study where lacustrine sedimentation occurs on a tectonically active half-graben within a key climate region (Lake Ifrah, Northwest Africa). We conducted conventional sedimentological and high-resolution sequence-stratigraphic analyses, integrated with palaeolimnological proxies (geochemical elements and ostracod species). Up to five facies models (accounting for lithological domination, wind-driven energy, and lake-level state) and three lowest rank T-R sequences, deposited since the Marine Isotope Stage-3 (MIS-3), have been identified. Periods with sustained high lake levels appear to be mainly precession-paced (as during MIS-3 and the Early Holocene), although the role of obliquity is shown to influence the hydrological budget as well. Furthermore, sedimentation dynamics are shown to respond to millennial timescale climate variability associated with North Atlantic cooling events (Dansgaard-Oeschger stadials, Heinrich Events) and, interestingly, to enhanced Saharan winds during the deglacial period. On the other hand, tectonism had a rather instantaneous effect on lake level and sedimentation. Two tectonic pulses marking instantaneous differential hanging-wall subsidence have triggered a sharp drop in relative lake level, hence conditioning a forced regression. We highlight the importance of the conventional high-resolution sequence stratigraphy in shaping our understanding of the cyclic interplay between orbital/sub-orbital and tectonic forcings, so as the resulting sedimentation dynamics and lake-level cycles in lacustrine settings. We stress the role of the forced regression concept and associated systems tract and bounding surfaces, as well as the importance of using ostracods and geochemical proxies to trace transgressions and cryptic surfaces with sequence-stratigraphic significance, such as the maximum flooding surface, in lacustrine settings. • Three lowest-rank T-R sequences developed in a low accommodation basin since MIS-3. • Five depositional systems build the T-R sequences imparting various controlling mechanisms. • Periods with precession minima are in sync with sustained high lake level. • Identification of falling-stage systems tracts afforded insights into tectonic pulses. [ABSTRACT FROM AUTHOR]

A prograding late Miocene carbonate platform in southern Spain revealing different sea-level pinning points was analysed with the aim to increase the accuracy of reconstruction of past sea-level changes. These pinning points are distinct diagenetic zones (DZ) and the position of reef-framework deposits. DZ1 is defined by the dissolution of bioclastic components and DZ2 by calcitic cement precipitation in dissolution pores. Calcite cements are granular and radiaxial fibrous, and are of meteoric origin as deduced from cathodoluminescence, EDX spectroscopy, as well as from δ 13 C and δ 18 O isotope analyses. DZ3 has moldic porosity after aragonitic bioclasts with minor granular calcitic cements. DZ1 and DZ2 indicate karstification and the development of a coastal palaeoaquifer during a sea-level lowstand. DZ3 diagenetic features are related to the final subaerial exposure of the section during the Messinian Salinity Crisis. Facies and diagenetic data reveal a complete cycle of sea-level fall (23 ± 1 m) and rise (31 ± 1 m). A robust age model based on magneto- and cyclostratigraphy for these deposits places this cycle between 5.89 and 5.87 Ma. Therefore, for the first time, this work allows a direct comparison of an outcrop with a pelagic marine proxy record of a specific Neogene sea-level fluctuation. [ABSTRACT FROM AUTHOR]

Abstract: The response of clay mineral assemblages to potential orbital forcing is tested in Mesozoic hemipelagic marl–limestone rhythmites of the Río Argos section (Betic Cordillera, Southeastern Spain). Along the section, marls are pervasively enriched in kaolinite and illite, whereas limestones are enriched in smectite-rich illite/smectite mixed-layers, suggesting that marl–limestone alternations are produced by cyclic high-frequency fluctuations of continental runoff. Spectral analyses show that clay mineral assemblages evolve accordingly to precession, obliquity and eccentricity cycles. Durations of ammonite zones are assessed at 535kyr for the Late Hauterivian Pseudothurmannia ohmi Zone and at 645kyr and for the Early Barremian Taveraidiscus hugii Zone. These durations are in agreement with other cyclostratigraphic estimates but significantly differ from the Geologic Time Scale 2004 and 2008. Clay minerals display enhanced amplitude of the eccentricity cycles during the Faraoni Oceanic Anoxic Event due to enhanced continental weathering conditions prevailing at that time. Sedimentary expression of the 405-kyr eccentricity is disturbed by palaeoclimate changes during the Faraoni OAE, challenging the hypothesis of Cretaceous OAE triggered by eccentricity cycles. Although palaeoceanographic events (e.g. Faraoni OAE) may induce disturbances in the clay mineral record, this study demonstrates the potential of these minerals to be used as a proxy for orbital calibration in Mesozoic times. [Copyright &y& Elsevier]

Abstract: The Neogene basins of Southern Cyprus provide a good opportunity to improve the knowledge of the paleoenvironmental changes involved in the triggering of the Messinian evaporite deposition in the Mediterranean, and of their chronology, which is still questionable with regards to the parameters responsible for the triggering of the salinity crisis. It is still difficult to discriminate the individual effects of tectonics, climate, global sea-level changes. In Cyprus, considerable progress has been made on the events leading to the MSC, since the 70''s, in high-resolution microfossil biostratigraphy, astrochronology, cyclostratigraphy and magnetostratigraphy. A study of the Tochni section, in the Psematismemos Basin, correlated with previously studied sections in the western Polemi and Pissouri basins, allows these regional paleoenvironmental changes to be correlated with the major events identified in other Mediterranean basins. The depth of the basins, in which evaporites were deposited, and the increase of salinity leading to the formation of evaporites are better constrained and studies confirm that restriction proceeded by steps throughout the Mediterranean. The very short time involved in the triggering of the onset of evaporite deposition in Cyprus basins is marked by tectonic instability, and development of very shallow water fauna and microbial communities indicating the water level lowered significantly just before the beginning of the massive gypsum precipitation. Correlation with other peri-Mediterranean basins, where similar changes have been observed, confirms that the period preceding the deposition of evaporites may correspond to the final closure of connections between the Atlantic Ocean and the Mediterranean Basin, leading to a sea-level drop and important hydrologic changes. [Copyright &y& Elsevier]

Abstract: The Cenozoic Alpine orogeny caused the partition of Tethys into several basins. During the Late Neogene, the Mediterranean attained its final configuration, whereas, eastwards, the Paratethys, isolated from the World Ocean, disintegrated progressively into a series of smaller basins. As a result, an endemic fauna developed in these basins, mainly composed of brackish to freshwater faunas, indicating an environment affected by changes in water salinity. These small basins of the Paratethys were named “Sea-Lakes” by Andrusov [Andrusov, D., 1890. Les Dreissenidae fossiles et actuelles d''Eurasie. Geol. min. 25, 1–683 (in Russian)]. Subsequently this name was translated into “Lac-Mer” [Gignoux, M., 1936. Géologie stratigraphique, 2°édition, Masson, Paris]. In the Mediterranean isolated from the Atlantic at the end of the Miocene (Messinian), thick evaporites deposited, consisting of a marine Lower Evaporite unit and an Upper Evaporite unit, mainly of continental origin. Ruggieri [Ruggieri, G., 1962. La serie marine pliocenica e quaternaria della Val Marecchia. Atti Acad. Sci. Lett. Arti. Palermo, 19, 1–169.] used the term “Lago-Mare”, to characterize the brackish to fresh water environment which occurred within the Mediterranean at the end of the Messinian. During recent decades, numerous scientific investigations concerning the history of the Messinian within the Mediterranean were devoted to the understanding of conditions prevailing after the deposition of the marine evaporites. Brackish to freshwater faunas are found in several outcrops and boreholes in the Mediterranean, both in the uppermost beds of gypsum and inter-bedded within the clastic sediments of the Upper Evaporite Unit, immediately preceeding the flooding by the marine Pliocene waters. These faunas, because of their similarities with the fauna described in the Paratethys, were named “Paratethyan”, or “Caspi-brackish” fauna, this leading some authors to imply a migration of these fauna from Paratethys to the Mediterranean. However, others refute this hypothesis. New data induced some researchers to consider that exchanges existed between the Mediterranean and the Eastern Paratethys and also between the Mediterranean and the Atlantic Ocean at the Miocene–Pliocene transition. These investigations now take advantage of the accurate time scales established by authors (biostratigraphy, cyclostratigraphy, magnetostratigraphy), allowing good stratigraphic correlations between the Mediterranean and the Paratethys, and precisions on the geodynamic evolution of this area. Furthermore, sediments at the base of the Zanclean (MPl1), locally containing brackish to fresh water faunas conducted authors to attribute this formation to an infra- or pre-Pliocene and also to a Lago-Mare “event”. Thus, the “Lago-Mare” concept drifted from its original meaning, and is evolving because of progresses in the understanding of the Mediterranean geodynamics and the adjacent areas during the Miocene–Pliocene transition. [Copyright &y& Elsevier]

Abstract The Middle Triassic Upper Muschelkalk carbonate ramp deposits in SW-Germany provide an excellent 'laboratory scale' analogue for vast epeiric basin fills such as in the Middle East. The Upper Muschelkalk and the entire Mesozoic overburden in SW-Germany were deposited on a complex mosaic of three major, differentially subsiding Variscan paleo-tectonic blocks: the Rhenohercynian, Saxothuringian and Moldanubian - subtly influencing the depositional facies pattern for long periods of time. This study is based on detailed sedimentological logs of 41 boreholes and surface outcrop sections and 39 gamma-ray logs, lithofacies analysis, and a 1-D and 2-D sequence stratigraphic analysis leading to a regional correlation integrating sequence architecture and marker beds. Using the subsurface 3D modelling tool Petrel, two nested geocellular reservoir models were generated: (i) a basin scale (201.5 × 325 km) Lithofacies Associations (LFA) model based on truncated Gaussian simulation (TGS); (ii) a field scale (50 × 50 km) Lithofacies Types (LFT) model based on sequential indicator simulation (SIS). The integrated 3D facies models reveal landward facies retrogradation with patchy isolated shoal bodies during the transgressive hemisequence and basinward facies progradation with well-connected large shoals within the regressive hemisequence. Models combined with structural maps show the influence of large Variscan block segments and smaller scale internal structural elements on the distribution, and the size of reservoir analogues, both shoal- and dolomite bodies. This relationship offers a new tool for exploration in epeiric carbonates using deep-seated paleo-tectonic patterns for the prediction of both hydrocarbon and geothermal reservoirs. [ABSTRACT FROM AUTHOR]

The middle Santonian-lower Campanian carbonate-mud dominated succession deposited in the northeastern margin of the South Iberian Ramp (La Cañadilla Fm, NE Spain) shows a complex set of interfingered facies developed in a low-energy and low-gradient shallow-marine to coastal environment. Three facies belts characterize the environment reconstructed in this work: (1) a low-energy shallow marine lagoon dominated by radiolitid rudist limestones and miliolid-rich facies with variable carbonate-mud content; (2) a transitional belt with a patchy distribution of ponds and mudbanks. This belt mostly consists of miliolid-rich limestones with variable amount of fenestral porosity, which are interfingered with charophytes and gastropod marls and limestones usually mixed with miliolids; (3) a coastal plain with strong freshwater influence characterized by the sedimentation of marls and limestones with charophytes, gastropods and root traces and intraclastic/black pebble limestones. The studied succession is arranged in high-frequency sequences, including meter-scale parasequences bounded by widespread flooding surfaces, which stack in five larger-scale shallowing-upward sequences (6–20 m thick). The time calibration of these sequences obtained from strontium isotopes and biostratigraphic data (benthic foraminifera) suggests a major control in the sedimentation by climate-driven low-amplitude sea level oscillations formed in tune with the long- and short-eccentricity orbital cycles. Cyclic sea level rises controlled the existence of widespread flooding events in the low-gradient carbonate ramp at the onset of parasequences, which in the studied marginal areas of the South Iberian Ramp were mostly sourced from the southern Tethyan realm. Therefore, the La Cañadilla Fm provides an example of a complex shallow marine to coastal system giving rise to a mosaic distribution of carbonate-mud dominated facies, with sedimentation mostly influenced by external factors resulting in a well-defined stratigraphic architecture. The similarities with modern analogous systems such as the Ten Thousand Islands of the Florida Bay are discussed in this paper. • La Cañadilla Fm deposited in a carbonate mud-dominated coastal plain to lagoon • A transitional facies belt with mudbanks and ponds is compared to Florida analogues. • A mid Santonian-early Campanian age is precised by strontium data. • Sea-level changes driven by eccentricity cycles had major control in sedimentation. [ABSTRACT FROM AUTHOR]