Sedimentary Sequence Research Articles

Depositional sequence and detrital zircon age spectra from Ediacaran to Early Cambrian at the northwestern Yangtze craton: Implication for the basin dynamics

Depositional sequence and detrital zircon age spectra from Ediacaran to Early Cambrian at the northwestern Yangtze craton: Implication for the basin dynamics

Geographic Information System and Multivariate Analysis Approach for Mapping Soil Contamination and Environmental Risk Assessment in Arid Regions

Heavy metal contamination in soil is a global issue threatening human health and ecosystems. Accurate spatial maps of heavy metals (HMs) are vital to mitigating the adverse effects on the ecosystem. This study utilizes GIS and multivariate analysis to evaluate HMs in agricultural soils from Al Ghat Governorate, Saudi Arabia, analyzing Al, As, Co, Cr, Cu, Fe, Mn, Ni, Pb, V, and Zn using ICP-AES in 35 soil samples. Methods included contamination factor (CF), enrichment factor (EF), risk index (RI), geoaccumulation index (Igeo), pollution load index (PLI), soil quality guidelines (SQGs), and multivariate analysis. The soils, characterized by sandy texture, low organic matter, and alkalinity due to arid conditions and high calcium carbonate, had the following HM concentrations (mg/kg) in descending order: Fe (11,480) ˃ Al (7786) ˃ Mn (278) ˃ Zn (72.37) ˃ Ni (28.66) ˃ V (21.80) ˃ Cr (19.89) ˃ Co (19.00) ˃ Cu (12.46) ˃ Pb (5.46) ˃ As (2.69). EF, CF, and Igeo suggest natural sources for most HMs, predominantly from the sedimentary sequence, with localized Zn, Pb, Co, Mn, and Cu enrichment linked to mixed natural and agricultural influences. PLI and RI indicated acceptable contamination levels, posing no ecological risk. All samples fell below SQG thresholds for As, Cu, Pb, and Cr, confirming minimal ecological threat. Statistical analysis highlighted sedimentary cover as the primary HM source, with agricultural activities contributing to Co, Cu, Ni, and Pb levels.

Electronic Impact of High-Energy Metal Deposition on Ultrathin Oxide Semiconductors.

High-energy metal deposition significantly impacts the performance and reliability of two-dimensional (2D) semiconductors and nanodevices. This study investigates the localized annealing effect in atomically thin In2O3 induced during high-energy metal deposition. The localized heating effect alters the electronic performance of In2O3 devices, especially in shorter channel devices, where heat dissipation is further constrained. This effect creates a conductivity gradient along the In2O3 device with higher conductivity near the metal contact, as observed by conductive atomic force microscopy (C-AFM). This gradient leads to a pronounced threshold voltage (Vth) shift as the channel length (Lch) decreases, resembling a short-channel effect but one driven by thermal mechanisms rather than conventional mechanisms. Furthermore, metals with higher latent heats can exacerbate these effects. We also show that reversing the deposition sequence and postdeposition oxygen annealing effectively suppress Vth shifts across different Lch. This work offers key insights into controlling thermal effects during fabrication to improve ultrathin oxide transistor performance.

Facies distribution, sequence stratigraphy, and reservoir quality of the Oligo-Miocene carbonate sequences (Asmari formation) in the Dezful embayment, SW Iran

The Asmari succession is among the greatest productive hydrocarbon-bearing rock units in the Middle East. This paper examines the biostratigraphy, sedimentary environment, and depositional sequence of the Asmari reservoir in the Haft-Kel Field. This succession in the Haft-Kel Field contains limestones, dolostones, anhydrites, and argillaceous limestones and is bounded between the Pabdeh and Gachsaran formations. Paleontological research has led to the creation of three assemblage zones in this region. These zones present an age range from the late Oligocene (Chattian) to the early Miocene (Aquitanian). Also, detailed petrographic examinations and facies analysis led to the recognition of 14 types of microfacies, ranging from open marine environments to intertidal and supratidal systems. The distribution and association of recognized microfacies proposed carbonate ramp-type platform deposition for the Asmari Formation. In addition, three third-order depositional sequences (sequences 1, 2, and 3) have been recognized through the Asmari Formation in the Haft-Kel Oil field that is well correlated with sequences IV, V, and VI proposed by van Buchem et al. (2010), respectively. Using the Hydraulic Flow Unit (HFU) concept, six rock types have been identified for the Asmari reservoir. Finally, three reservoir zones, comprising none, moderate, and good reservoir zones, were introduced for the Asmari reservoir in Haft-Kel Field. No reservoir zones are visited in the lower part of the formation in depositional sequence 1 and to some extent in the Low Stand Systems Tract (LST) part of depositional sequence 2 and 3, while moderate to good reservoir zones are developed in the upper intervals of the formation, especially in the High Stand Systems Tract (HST) parts of depositional sequence 2 and 3.

Assessments of the earliest bats from the Quaternary of Serra da Mesa (Goiás, Brazil): phylogenetic insights and biogeographic modelling on the new extinct species of Rhinophylla, the first fossil record of the subfamily Rhinophyllinae (Chiroptera, Mammalia)

ABSTRACT Recovered from Quaternary deposits in Carneiro Cave (Serra da Mesa, Brazil), associated with a clayey-sandy sedimentary influx older than the overlying calcite layer, which has been dated to 182.8 ± 1.2 ka, a new extinct species of Rhinophylla is described based on a proximal radio fragment. This discovery represents one of the three oldest occurrences of Chiroptera in the exposed stratigraphic profile. The fossil record of Chiroptera consists of 1,117 bone fragments, distributed across Pleistocene and Holocene sedimentary packages. The chronology of this sedimentary sequence is established using dated layers, all of which are fully consistent with their order of deposition. A comparative study of the radioulnar morphology was conducted to determine the taxonomic identity of the new fossil bat. A strict consensus tree for phyllostomids was obtained, surprisingly consistent with recent molecular phylogenies, unequivocally places the new fossil in the subfamily Rhinophyllinae. Biogeographic modelling of Rhinophylla, typically characterised by an ecomorphology of small specialised epiphytic frugivores, suggests that around 200 ka (the fossil’s age reference) the genus may have had a broader distribution across Central Brazil than is observed today. This is consistent with the fact that Rhinophylla is currently absent in the surrounding region of the Carneiro Cave.

A Novel Protocol for Reconstructing Depositional Histories of Anthropogenic, Sedimentary Records: the Case of the Holocene-Deep Kirkhellaren Cave Deposits in Coastal Arctic Norway

ABSTRACT This paper presents a novel protocol for reconstructing formation processes of archaeological depositional sequences, applied to Holocene-wide cave deposits located on a remote coastal island in Arctic Norway as a case study. Extensive GPR surveying is correlated with geochemical analysis and in situ environmental deposit monitoring for sedimentary fingerprinting and forecasting of future preservation of organic remains. Subsurface deposit characteristics are integrated with a high-precision, laser-based 3D-reconstruction of the cave, enabling triangulation with historic photos and local informant knowledge that facilitate modeling and quantification of erosional history. The results showcase detrimental depletion of critical organic heritage, accelerated by the removal of protective surface layers after the a.d. 1930s. Critically, subsurface deposits are trending towards overshooting a threshold for accelerated in situ degradation. The results act as a direct validation of the methodology. Measures for future protection of similar archaeological deposits are discussed and an outline of the general applicability of the protocol.

Water Table Fluctuations Control Nitrate and Ammonium Fate in Coastal Aquifers

AbstractCoastal aquifers experience water table fluctuations that push and pull water and air through organic‐rich soils. This exchange affects the supply of oxygen, dissolved organic carbon (DOC), and nitrogen (N) to shallow aquifers and influences groundwater quality. To investigate the fate of N species, we used a meter‐long column containing a sequence of natural organic topsoil and aquifer sediments. A fluctuating head was imposed at the column bottom with local, nitrate‐rich groundwater (16.5 mg/L NO3‐N). We monitored in‐situ redox potential and collected pore water samples for analysis of inorganic N species and DOC over 16 days. Reactive processes were more complex than anticipated. The organic‐rich topsoil remained anaerobic, while mineral sediments beneath alternated between aerobic, when the water table dropped and sucked air across preferential flow paths, and anaerobic conditions, when the water table was high. A fluid flow and reactive transport model shows that when the water table rises into organic‐rich soils, it limits the flow of oxygen, while the soils release DOC, which stimulates the removal of nitrate from groundwater by denitrification. At the end of the experiment, we introduced seawater to the column to mimic a storm surge. Seawater mobilized N and DOC from shallow soil horizons, which could reach the aquifer if the surge is long enough. These processes are relevant for groundwater quality in developed coastal areas with anthropogenic N sources, as climate change and rising seas will drive changes in water table and flood dynamics.

Palaeoenvironmental and palaeoclimatic characterization of Upper Jurassic sedimentary sequences with dinosaur footprints of the M’Goun Geopark (High Atlas, Morocco).

Palaeoenvironmental and palaeoclimatic characterization of Upper Jurassic sedimentary sequences with dinosaur footprints of the M’Goun Geopark (High Atlas, Morocco).

Deposition of single-phase monoclinic Cu2SnS3 thin films on Mo-coated substrates by dual-source fine-channel mist CVD

Abstract Single-phase monoclinic Cu2SnS3 (CTS) thin films on Mo-coated soda-lime glass (SLG) substrates were fabricated through dual-source fine-channel mist chemical vapor deposition (CVD) by optimizing the deposition sequence and annealing process. The conventional deposition process using mist CVD caused Mo dissolution, thereby hindering CTS deposition on the Mo-coated SLG substrate. Therefore, to prevent Mo dissolution, a two-step deposition process was employed—initially, a Cu–Sn–S thin film was deposited briefly, followed by drying before the second deposition. This approach enabled deposition of CTS thin films on the Mo-coated SLG substrates. In addition to the fabrication of single-phase monoclinic CTS thin films, we attempted in-situ annealing, annealing with flowing mist, and cover annealing, i.e., annealing while covering the deposited film with an SLG substrate in in an N2 atmosphere. After in-situ and cover annealing processes, the Raman spectra showed only single-phase monoclinic CTS.

Predicting the presence of tephra layers in lacustrine deposits using spectral gamma ray data: An example from Lake Chalco, Mexico City.

Spectral gamma ray borehole logging data can yield insights into the physical properties of lake sediments, serving as a valuable proxy for assessing climate and environmental changes. The presence of tephra layers resulting from volcanic ash deposition is not related to climate and environmental conditions. As a result, these layers pose challenges when attempting to analyze paleoclimate and environmental time series. Gamma rays are composed of photons, which are elementary particles of electromagnetic radiation. Tephra layers emit photons at specific energy levels that create a distinct pattern in their gamma-ray energy spectrum. The gamma-ray signature of tephra layers varies depending on the stage of the volcanic eruption. Additionally, there is a significant difference between the gamma-ray signature emitted by tephra layers and that of the background lake sediments. A composite signature can be used to predict tephra layers from background sediments by combining several gamma-ray signatures of tephra layers at different depths. We propose five-step protocol for detecting tephra layers within sediments through the utilization of gamma-ray spectroscopy. This protocol is based on a combination of physical aspects of gamma-ray spectroscopy and geological information specific to the lake system being studied. A subset of the training dataset is used, consisting of known tephra and non-tephra layers. The protocol involves identifying similarities between known tephra layers, analyzing differences in gamma-ray signals between tephra and non-tephra layers, and studying the composition of energy channels at various depths within the training dataset. Multiple linear regression models are used to predict the relationship between the composition of tephra layers as a dependent variable and the constituent energy channels of the gamma-ray signal as independent variables. The proposed protocol has the potential to accurately detect and identify thick tephra layers (> 10 cm in thickness) based on the rate of spectral gamma ray measurement in sedimentary sequences. This approach could enhance stratigraphic resolution by enabling finer subdivision of layers in an interior basin.

Subduction-collision and rapid uplift of the NW Yangtze Block during the Ediacaran-Cambrian transition: new evidence from the shoshonite series

ABSTRACT The NW Yangtze Block has long been regarded as a passive continental margin during Ediacaran and Cambrian. However, with the deepening of the regional geological survey and deep oil and gas exploration, the depositional sequence and palaeogeographic patterns of Ediacaran and Cambrian in the Sichuan basin are not consistent with the general sedimentary evolution process of passive margin more and more. To fully understand the tectonic property and palaeogeography of the NW Yangtze Block, a comprehensive study of the whole rock geochemistry, zircon U-Pb chronology and Hf isotopic composition analysis were carried out on the Weimen volcanic rocks, which mainly consist of trachyte, trachy-andesite, andesite, dacite, and rhyodacite in Maoxian area. They have high light rare earth element (LREE) and large ion lithophile element (LILE) concentrations, but are depleted in high field strength elements (HFSE). They are characterized by having high K2O+Na2O (5.60–9.48%), MgO (1.47–4.58%), Ce/Yb (11.67–25.79), and normalized hypersthene (Hy = 2.14–14.17), indicate an unambiguous feature of the shoshonite series. LA-ICP-MS zircon U-Pb dating results show that the volcanic rocks have crystallization ages ranging from 528 Ma to 523 Ma, with positive zircon εHf (t) ranging from + 1.31 to + 5.26. In combination with previous studies, the early Cambrian shoshonite series in Maoxian area are interpreted to be formed in a continental collision setting. Therefore, the discovery of the shoshonite series suggests that the NW Yangtze Block has experienced an important process of continental subduction and collisional orogeny in response to the Gondwana assembly, and consequently provided a large amount of terrigenous sources to rapidly fill into the early Cambrian foreland basin.

A Deccan Large Igneous Province related Maastrichtian regolith of Lameta Formation, Central India: Insights into the genesis and development of calcrete profiles and implications for palaeoclimate variability

ABSTRACTEmplacement of volcanics of the Deccan Large Igneous Province in the late‐Maastrichtian to early‐Danian has been linked to global climatic perturbations and the related biotic crisis. Sedimentary sequences associated with these lavas, known as infra‐trappean and inter‐trappean successions, preserve records of this Large Igneous Province induced climatic and biotic changes. The Lameta Formation of Jabalpur is the type section for the infra‐trappean succession; it preserves a unique stack of 13 calcrete profiles and one calcic‐vertisol, which together constitute the Mottled Nodular Beds. This stratigraphic unit evolved over a significant time period, most likely a few hundred thousand years in Chron C29R, making it a unique section suitable for obtaining insights on terminal Cretaceous palaeoclimatic variability. Micromorphological, clay‐mineralogical, geochemical and stable carbon‐isotopic (organic matter) data of calcretes of the Mottled Nodular Beds have been used to understand their genesis and obtain insights on climatic variability during their formation. These calcretes/calcareous palaeosol profiles are largely characterized by alpha‐fabric with the development of some biogenic features indicating predominantly evaporation/evapotranspiration driven carbonate precipitation with minor biochemically induced precipitation, respectively. Strontium isotopic compositions of the carbonate fraction of these calcretes indicate derivation of calcium from the Precambrian Mahakoshal Group marbles. On the basis of multiple datasets, these calcretes are interpreted to be pedogenic having formed in the soil‐vadose zone following the per descensum model. Based on a multiproxy approach that includes micromorphology, clay‐mineralogy, geochemistry (Mean Annual Precipitation and salinization) and stable carbon isotope ratio (organic matter), the conditions of formation of the Mottled Nodular Beds in C29R are interpreted to have varied mostly from semi‐arid to sub‐humid, with two intervening shorter arid episodes in the middle and upper parts of this succession. This climatic variability broadly aligns with the recently suggested changes in eruptive dynamics in the neighbouring Malwa Plateau of the Deccan volcanic province.

Understanding Taphonomy Through 3D and 2D Records: A Case Study from the Tropical Maya Area

Mortuary archaeology in the Maya region is complicated by both cultural and natural factors. Distinctive funerary depositional and post-depositional secondary activities, in addition to tropical climate, contribute to the complexity of pre-Hispanic Maya funerary practices. This paper proposes to merge 2D and 3D recording data to obtain a comprehensive understanding of the taphonomic phenomena that affect heavily altered burials at the site of Palenque, Mexico. Employing an archaeothanatological approach, we argue that careful 3D imaging, integrated with earlier produced legacy data, provides additional insight into the formation processes of funerary contexts compared to previous methods. Digital photogrammetric analyses improve our capacity to reconstruct joint articulations of the body and its original funerary deposition in situ. The results of this research elucidate the intentional activities that led to the archaeological arrangement of the grave assemblage. By noticing the degree of articulation and clarifying the pace at which bodies decomposed, these results showcase the depositional sequence of one collective mixed burial from Group IV, a domestic compound in Palenque. These results suggest the viability of 3D methodologies in assessing post-depositional disturbances and movements of the body, both for illuminating funerary taphonomic practices and serving as important recording procedures for the future.

Late Middle to Late Ordovician Phosphate Accumulation of the Moyero River Section (Siberia): A Record of Upwelling and Global Cooling

The phosphate-bearing rocks (phosphate rocks and phosphorites) were studied over a 45-meter interval of the Moyero river section, covering the upper part of the Darriwilian and the lower part of the Sandbian stages of the Ordovician. These rocks were investigated by field observations and laboratory methods, including optic and scanning electron microscopy, X-ray diffraction analyses. The accumulation of phosphatic matter is manifested in carbonates, sandstones, and aleurolites in the form of grains (ooids and peloids), intraclasts, phosphatic and phosphatized shells. In argillites, it is represented by cryptocrystalline matter. Phosphate matter consists of fluorapatite. The peaks of phosphate accumulation are associated with the formation of layers of physically reworked granular phosphorites (condensation horizons) directly above the depositional sequence boundaries. The formation of the studied phosphate-bearing rocks during the Darriwilian-Sandbian transition was influenced by a combination of global (Great Ordovician Biodiversification Event (GOBE), reduction in sea surface temperature, atmospheric CO2, high sea level, flooding of craton margins) and regional (equatorial position of Siberia, arid climate, facies) factors. Global conditions led to the enrichment of seawater with phosphorus and the effect of upwelling. Regional conditions determined the characteristics of phosphate formation. Studied phosphate-bearing rocks can be considered as a record of upwelling on the Siberian craton during the Middle-Late Ordovician transition and one of the manifestations of long-term global cooling started early in the Middle Ordovician.

The reasons for the inheritance of the composition and properties of red-colored soils of the modern weathering crust within the western part of the Sichuan Basin of China

In this work, we conducted an experimental evaluation and analysis of the characteristics and makeup of red-colored rocks from four representative Cretaceous and Jurassic sedimentary sequences in the western Sichuan Basin of China, as well as their weathering products. To determine the direction of weathering processes and the cause-and-effect link between the characteristics and composition of the parent rocks and the excess chemical components in the weathered soils, the chemical index of alteration was calculated. The findings demonstrated that, with regard to features like color, density of solid component, organic carbon content, granulometric composition, pH, mineral composition, and content of main chemical elements, all samples of weathered (dispersed) soils are quite comparable to the parent rocks. All samples of weathered soils and parent rocks exhibit similar chemical weathering characteristics and an index, according to the results of the CIAcorr calculation and the examination of the A–CN–K triangle diagrams. Furthermore, all of them have attained a moderate level of chemical weathering, with samples from Jurassic rocks (J3p, J3s, and J2s) having far lower weathering intensities than those from Cretaceous rocks (K1c). The red-colored rocks are characterized by weak chemical weathering and rapid development of physical weathering. This weathering characteristic can be attributed to the parent rock’s uniform texture and mostly clayey composition, which break down readily in environments with high humidity and plenty of heat. The low level of chemical weathering is due to the fact that the parent rock itself has undergone a significant change in chemical composition during sedimentation and subsequent diagenesis, and has acquired a high degree of resistance to subsequent transformation under modern conditions. Therefore, the characteristics and makeup of purple soil are mostly determined by the parent rock.

Improving the age constraints on the archeological record in Scladina Cave (Belgium): new speleothem U–Th ages

Abstract. The sedimentary sequence in Scladina Cave (Belgium) is well-known for its rich Middle Paleolithic assemblages and its numerous faunal remains. Of particular interest is the presence of a nearly complete mandible of a Neanderthal child. To place all of these finds into the correct chronostratigraphic context, various dating techniques have been applied over the past decades. This resulted in a reasonably well-constrained age model, roughly spanning the last glacial cycle. Age constraints of the lower part of the Scladina sequence as well as from the underlying Sous-Saint-Paul Cave were, however, absent until now. Previous attempts to date several speleothem layers in Scladina Cave using U–Th dating were only partly successful, presumably because diagenetic alteration of speleothem material compromised the ages. In the present study we reassessed U–Th dating of various speleothem levels in Scladina Cave, applying state-of-the-art U–Th dating and carefully selecting material that experienced little to no diagenetic alteration. The new results constitute a robust age framework for the Scladina sequence, which provides precisely dated stratigraphic anchor points that improve the previous age model. Furthermore, new U–Th analyses for speleothems from the lower part of the Scladina sequence and from the Sous-Saint-Paul sequence document Middle Pleistocene ages, making this one of the longer fossil-rich cave sedimentary sequences in NW Europe. The new data confirm that speleothem growth predominantly took place in periods of warmer climate, while siliciclastic sediments characterize the colder intervals. New speleothem ages further suggest that the Neanderthal mandible found in the sequence and previously placed in Marine Isotope Stage 5a or 5b could potentially be as old as Marine Isotope Stage 5d.

Effects of Trophic State on the Composition and Distribution of Bacteria in the Surface Sediments of Lake Taihu

ABSTRACT1. The trophic state of water significantly affects the structure of bacterial communities in sediments. The direct and indirect impacts of trophic state, along with trophic‐induced changes in the properties of organic matter, on the composition and distribution of bacteria in sediments, remain largely unknown.2. We collected surface sediments from 21 sites across five areas of Lake Taihu, the third largest freshwater lake in China. These sites represented a range of trophic states from mesotrophic to moderately eutrophic. We investigated how trophic state influences bacterial composition and distribution in the surface sediments of Lake Taihu.3. Proteobacteria, Firmicutes and Bacteroidetes were the most abundant phyla identified in the DNA sequences of surface sediments from the sampling sites in Lake Taihu, regardless of the water trophic state. The relative abundance of Proteobacteria and Firmicutes in the surface sediments increased with trophic level index (TLI) of the water column. In contrast, the relative abundance of Bacteroidetes, Acidobacteria and Fibrinobacteria decreased with increasing TLI. The α‐biodiversity of the sediment bacterial community in Lake Taihu did not vary significantly among different water trophic states. However, surface sediments from sites with varied trophic states exhibited different groups of bacteria that were either specifically present or in higher relative abundance.4. Several factors influenced the sediment bacterial communities in Lake Taihu, including sediment total nitrogen, sediment total phosphorus, sediment organic carbon, δ13C and trophic state. However, the primary influencing factors varied between sites and trophic states. For mesotrophic states, sediment organic carbon was the most important factor, while for moderately eutrophic states, trophic state was the most significant factor.5. Our findings provide evidence for both the direct and indirect influences of water trophic state on the composition and distribution of bacteria in sediments.

Underwater discharge of fluids at the bottom of lake Baikal: composition, sources and migration peculiarities within the MSU structure

The paper presents geochemical study of bottom sediments from the MSU structure located on the large Gydratny Fault in the Central Basin of Lake Baikal at a depth of 1380 m. The first detailed data on the spatial variations in the qualitative and quantitative composition of the pore waters are presented. Pioneering data were obtained on Li, B, and Sr contents in the pore water of the sediments. It has been established that fluids are actively discharged within the MSU structure, and the main pathways of their near-surface migration are confined to the tops of hills of this structure on the downthrown fault block. The fluids are highly mineralized (up to 2900 mg/L), showing the highest mineralization ever found in Lake Baikal sediments. The waters are significantly enriched in Mg, Li, B, and Sr but depleted in K. The waters are thought to be generated by the processes of authigenic formation and illitization of smectite at depths of 1 to 2.5 km in the sedimentary sequence. The maximum values of concentration gradients are recorded in the pore waters of the sediments of the western hill, which may indicate a gradual westward shift of the center of the fluid seepage activity along the fault.

Moganite in agates from shungite rocks of the Paleoproterozoic Onega basin (Karelia)

The monocline phase of silica – moganite for the first time has been found in carbon-rich sedimentary rocks (shungites) of Zaonega formation within the Paleoproterozoic Onega basin. Moganite forms intergrowths with fibrous chalcedony in concentric layers of agates, which are presumably associated with pseudomorphic replacement of carbonate nodules. According to local Raman spectroscopy analyses, content of moganite within individual chalcedony bands is not homogenous and varies in the range of 22–50%. The estimated values of moganite content are very high for agates formed in the Paleoproterozoic rocks aged 2050 Ma and indicate a large temporary gap between formation of the sedimentary sequence and the hydrothermal process that initiated agate mineralization.

Sequence and cyclostratigraphic analysis of Paleocene carbonate sediments in the Chicxulub impact crater: Implications for sea level change and climate dynamics

Sequence and cyclostratigraphic analysis of Paleocene carbonate sediments in the Chicxulub impact crater: Implications for sea level change and climate dynamics