Global Stratotype Section Research Articles

Organic walled dinoflagellate cyst biostratigraphy of the Bartonian/Priabonian GSSP Alano di Piave section, NE Italy

The present paper augments the multidisciplinary stratigraphic analysis of the Global Stratotype Section and Point (GSSP) Bartonian-Priabonian boundary Alano di Piave section (NE Italy). Twenty-seven stratigraphically signficant organic walled dinoflagellate cyst events, calibrated against the magnetostratigraphic polarity timescale, and earlier established zonations based on calcareous microfossils are recognized. Among these events the first occurrence (FO) of Oligokolpoma agniniae sp. nov. (~8 m below the GSSP boundary), and the FO of Reticulatosphaera actinocoronata (~8 m above the GSSP boundary) may be considered as additional stratigraphic indicators for the Bartonian-Priabonian boundary. Six new potentially stratigraphically significant species Heteraulacacysta alanoensis sp. nov., Heteraulacacysta reticulata sp. nov., Impagidinium bellunoensis sp. nov., Impagidinium veneziaense sp. nov., Lophocysta domenicorioi sp. nov., and Oligokolpoma agniniae sp. nov. are formally described.

Cyclostratigraphy of late Cambrian marine sedimentary records and reconstruction of Earth-Moon system parameters

The Cambrian period is an important era in geological history, marked by numerous major geological and biological events. To better understand these events, it is important to establish a high-precision chronostratigraphic framework. An astronomical time scale can be created by the identified Milankovitch cycles in well-preserved stratigraphic successions. Duibian B section in Jiangshan (Zhejiang Province, China) is the global stratotype section and point (GSSP) for the Jiangshanian Stage, and this section provides well-preserved records covering the upper Paibian to lower Jiangshanian stages. In this study, we use high-resolution magnetic susceptibility record to conduct cyclostratigraphic analysis of the Duibian B section. Our results indicate that the 2.44 m, 0.84–0.73 m, 0.20–0.19 m, and 0.12–0.09 m sedimentary cycles may represent long-eccentricity, short-eccentricity, obliquity, and precession cycles, respectively. Using the stable 405-kyr eccentricity cycles, we constructed an ∼5.96 Myr floating astronomical time scale to calibrate agnostoid trilobite zones. In addition, we reconstructed the precession rate k from geological records, and our result provides an insight into the Earth-Moon distance and length of day in the late Cambrian (Paibian–Jiangshanian, ∼494.2 Ma). It enriches our understanding of the Earth-Moon evolutionary history in deep time.

Calcareous nannofossil biostratigraphy, bioevents, and palaeoecological interpretation of the lower-middle Miocene outcrops in west central Sinai (Egypt)

The Burdigalian/Langhian (B/L) boundary has not yet been designated as a Global Stratotype Section and Point (GSSP), despite various proposed zonal schemes. In the Gulf of Suez region of Egypt, the Burdigalian-Langhian successions are notable for hosting significant hydrocarbon reservoirs within a tectonic rift setting. Therefore, biostatigraphy plays a crucial role in exploration endeavors in this area. The nannofossil biostratigraphy is investigated in two sections, Wadi Baba and Wadi Gharandel, of the lower-middle Miocene from west-central Sinai. Three biozones, NN3 (Sphenolithus belemnos) Zone, NN4 (Helicosphaera ampliaperta) Zone, and NN5 (Sphenolithus heteromorphus) Zone, are identified from the studied interval. The NN4 Zone could be divided into MNN4a/b and MNN4c. Important biovents are discussed, such as the S. heteromorphus paracme interval and the first occurrence and evolution of the Discoaster exilis and Discoaster variabilis groups. Based on the cluster analysis, the recorded taxa can be subdivided into four groups that reflect their palaeoclimatic preferences. The paleoecological interpretation of the studied Rudies Formation indicates prevailing cool and eutrophic nutrient conditions based on the dominance of taxa such as Coccolithus pelagicus, Reticulofenestra minuta, and Cyclicargolithus floridanus. The nannofossil taxa responses to sea level curve are interpreted. Fluctuations in taxa abundance and diversity indicate a slight rise in the sea level at the base of the Burdigalian followed by sudden drop in the sea level at the middle Burdigalian. High sea-level conditions prevailed again until the B/L boundary. During the Langhian period, many small-scale fluctuations in sea-level curve are detected.

ERRATUM: Stratigraphy of the Cretaceous/Paleogene (K/Pg) boundary at the Global Stratotype Section and Point (GSSP) in El Kef, Tunisia: New insights from the El Kef Coring Project

“X-ray diffraction (XRD)” rather than “X-ray fluorescence (XRF)” was printed in the captions to Figure 7, Figure 9, and Figure 10. See PDF file for details.

Belemnites of the family Belemnitellidae Pavlow, 1914 from the Late Cretaceous Maastrichtian stage in the Northern Hemisphere.

The currently defined Global Stratotype Section and Point for the Campanian/Maastrichtian boundary at Tercis (France) lacks any belemnite record. However, the detailed correlation of Tercis with the Kronsmoor section in northern Germany has enabled recognising this boundary in terms of belemnite stratigraphy close to the first appearance datum (FAD) of Belemnella obtusa Schulz, 1979. Originally, the FAD of the genus Belemnella Nowak, 1913 (e.g. of Belemnella lanceolata (von Schlotheim, 1813)) has been widely used for defining the base of the traditionally understood Maastrichtian stage in the Boreal Realm. Belemnella appeared almost contemporaneously across a significant portion of epicontinental Europe in what is now considered topmost Campanian and dominated the lower Maastrichtian belemnite assemblages, co-occurring with Belemnitella d'Orbigny, 1840 and rare Fusiteuthis Kongiel, 1962. It disappeared in Western and Central Europe during the mid-Maastrichtian, and as a consequence, the FAD of Belemnitella junior Nowak, 1913 served as a biomarker defining the base of the upper Maastrichtian substage. It is only at the end of the Maastrichtian that the genus Neobelemnella Naidin, 1975 became abundant, replacing Belemnitella steadily from the east to the west as the dominating species. The factors underlying those remarkable shifts in belemnite assemblages remain uncertain, but various environmental elements, especially water depth and temperature, in addition ocean currents, and oceanic chemical composition are considered influential.

The Global Stratotype Section and Point (GSSP) of the Langhian Stage and of the Middle Miocene Subseries

The Global Stratotype Section and Point (GSSP) of the Langhian Stage and of the Middle Miocene Subseries

Redefinition of the Global Stratotype Section and Point (GSSP) and new Standard Auxiliary Boundary Stratotype (SABS) for the base of Wuchiapingian Stage (Lopingian Series, Permian) in South China

Redefinition of the Global Stratotype Section and Point (GSSP) and new Standard Auxiliary Boundary Stratotype (SABS) for the base of Wuchiapingian Stage (Lopingian Series, Permian) in South China

Initial results of coring at Prees, Cheshire Basin, UK (ICDP JET project): towards an integrated stratigraphy, timescale, and Earth system understanding for the Early Jurassic

Abstract. Drilling for the International Continental Scientific Drilling Program (ICDP) Early Jurassic Earth System and Timescale project (JET) was undertaken between October 2020 and January 2021. The drill site is situated in a small-scale synformal basin of the latest Triassic to Early Jurassic age that formed above the major Permian–Triassic half-graben system of the Cheshire Basin. The borehole is located to recover an expanded and complete succession to complement the legacy core from the Llanbedr (Mochras Farm) borehole drilled through 1967–1969 on the edge of the Cardigan Bay Basin, North Wales. The overall aim of the project is to construct an astronomically calibrated integrated timescale for the Early Jurassic and to provide insights into the operation of the Early Jurassic Earth system. Core of Quaternary age cover and Early Jurassic mudstone was obtained from two shallow partially cored geotechnical holes (Prees 2A to 32.2 m below surface (m b.s.) and Prees 2B to 37.0 m b.s.) together with Early Jurassic and Late Triassic mudstone from the principal hole, Prees 2C, which was cored from 32.92 to 651.32 m (corrected core depth scale). Core recovery was 99.7 % for Prees 2C. The ages of the recovered stratigraphy range from the Late Triassic (probably Rhaetian) to the Early Jurassic, Early Pliensbachian (Ibex Ammonoid Chronozone). All ammonoid chronozones have been identified for the drilled Early Jurassic strata. The full lithological succession comprises the Branscombe Mudstone and Blue Anchor formations of the Mercia Mudstone Group, the Westbury and Lilstock formations of the Penarth Group, and the Redcar Mudstone Formation of the Lias Group. A distinct interval of siltstone is recognized within the Late Sinemurian of the Redcar Mudstone Formation, and the name “Prees Siltstone Member” is proposed. Depositional environments range from playa lake in the Late Triassic to distal offshore marine in the Early Jurassic. Initial datasets compiled from the core include radiography, natural gamma ray, density, magnetic susceptibility, and X-ray fluorescence (XRF). A full suite of downhole logs was also run. Intervals of organic carbon enrichment occur in the Rhaetian (Late Triassic) Westbury Formation and in the earliest Hettangian and earliest Pliensbachian strata of the Redcar Mudstone Formation, where up to 4 % total organic carbon (TOC) is recorded. Other parts of the succession are generally organic-lean, containing less than 1 % TOC. Carbon-isotope values from bulk organic matter have also been determined, initially at a resolution of ∼ 1 m, and these provide the basis for detailed correlation between the Prees 2 succession and adjacent boreholes and Global Stratotype Section and Point (GSSP) outcrops. Multiple complementary studies are currently underway and preliminary results promise an astronomically calibrated biostratigraphy, magnetostratigraphy, and chemostratigraphy for the combined Prees and Mochras successions as well as insights into the dynamics of background processes and major palaeo-environmental changes.

Paleocene–Eocene boundary in the Gabal El-Gir, east Qena, Egypt: Paleoenvironment and sequence stratigraphy interpretations

Comprehensive field, litho-, biostratigraphy, and paleoenvironmental studies of the upper Paleocene–lower Eocene (P–E) boundary interval in the Gabal El-Gir area were conducted. Two selected sections El-Gir-1 and El-Gir-2 were investigated. The prevailed paleoenvironmental conditions were discussed in the frame of the nannofossils, planktonic, and benthic foraminiferal assemblages. Benthic foraminifera assemblages indicate a remarkable turnover across the PETM. The extinction of Angulogavelinella avnimelechi at the base of the PETM represents a significant marker for the base of the benthic foraminifera extinction event at this site and other neritic sites in the Tethyan region. The dominance of calcareous planktonic excursion taxa at the base of the PETM indicates adaptation to extremely warm sea surface temperatures and low nutrient levels. Also, our data suggests that the biotic responses to environmental change in the early Eocene resembled those observed in the early Eocene hyperthermals at the nearbay Dababiya and El-Ballas sections. This could indicate that similar processes characterized the Egyptian sedimentary basin during the early Eocene. Stratigraphically, despite the limited distance between the studied sections, the Dababiya Quarry Member (DQM) in El-Gir-1 resemble those of the Global Stratotype Section and Point (GSSP) but reduced in thickness. While in El-Gir-2, the lower part of the DQM was missing. These findings could indicate that the DQM was deposited in a submarine channel. Three third-order depositional sequences were recognized covering the P–E interval. The reconstructed sea level curve shows the presence of eustatic similarities with the global sea level.

Imprecision and instability of the Phanerozoic chronostratigraphic scale: A solution

The use of the GSSP (Global Stratotype Section and Point) method to define a Phanerozoic chronostratigraphic timescale has resulted in imprecision and instability because most of the primary signals for correlation of the GSSPs are single taxon biotic events that are inherently diachronous and restricted in their paleogeographic distributions by the limitations of sampling, facies and provincialism. Greater precision and stability can be achieved by using non-biotic criteria as the primary signals of GSSPs-numerical ages, magnetostratigraphy, isotope excursions and others. If correlation is aided by close association of the non-biotic primary signal with secondary signals of geographically widespread, ergo global, extent, such non-biotic primary signals of GSSPs will produce a more precise and more stable chronostratigraphic timescale.

Upper Carnian to Rhaetian (Upper Triassic) conodont and carbon-isotope stratigraphy of the Csővár borehole succession, Hungary

A total of 125 samples from core from the Csővár borehole (north-central Hungary) were investigated for conodont bio- and carbon-isotope chemostratigraphy. This 620 m thick continuous pelagic carbonate succession comprises strata from the upper Carnian to upper Rhaetian, including both, the Carnian-Norian and the Norian-Rhaetian stage boundaries. The mass occurrence of the Metapolygnathus communisti conodont group followed by the occurrence of Primatella gulloae mark the base of the Norian in the lowermost part of the section, which allows good correlation with the Pizzo Mondello section (Sicily, Italy). The lower Norian conodonts of the core belong predominantly to the genus Ancyrogondolella. Subdivision of the middle Norian interval is hampered by the lack of fully adult specimens. The upper Norian shows a greater diversity than the rest of the Norian, and the rich assemblages give an insight into the evolutionary transition from Misikella hernsteini to Mi. posthernsteini (sensu stricto). The first occurrence of Mi. ultima in the core changes the previous views of the thickness of the upper Rhaetian in the Csővár area and emphasizes the necessity of re-calibration of the isotope stratigraphic results of previous studies. The carbon-isotope results show distinct fluctuations and trends. Some of them are similar to literature data, others are different. It can be stated from the new data that a ∼ 2 ‰ long-term δ13C background decline throughout the Norian is most probably global in extent. Negative carbon-isotope excursions occur in Norian substages: (upper) Alaunian, lower Sevatian, middle Sevatian and upper Sevatian. Distinct positive δ13C excursions are present across the Alaunian-Sevatian boundary and the Norian-Rhaetian boundary, and the climax of the latter is located in the lower part of the posthernsteini Zone. This last isotope event is particularly important because at the Global Stratotype Section and Point (GSSP) candidate for the base of the Rhaetian stage at Pignola (Southern Apennines, Italy) a distinct negative δ13C excursion has been reported for this stratigraphic level.

High-resolution conodont unitary association zonations (UAZs) across the Induan-Olenekian boundary (Lower Triassic): A global correlation

A precise global timescale for the Lower Triassic Series is essential to understand the sequence of events following the end-Permian mass extinction. A crucial step toward providing the necessary high-resolution chronostratigraphic framework for this interval is the final resolution of a long debated Global Stratotype Section and Point (GSSP) for the Induan-Olenekian boundary (IOB; Lower Triassic). Lower Triassic conodont biostratigraphy has been studied around the world in the past decades, with significant recent progress in the recognition of evolutionary lineages and new collections leading to a refined definition of the IOB. The worldwide distribution of Novispathodus waageni sensu lato has been proposed as the marker defining the IOB. This study recognized 15 or 9 unitary associations across the IOB interval worldwide depending on the taxa and sections that are utilized. The first analysis comprises 37 conodont species from 31 globally representative sections distributed around circum-Paleotethys and Panthalassic oceans, including South China, West Pakistan, northern India, North America and others. This analysis resulted in 15 unitary associations with the probable IOB being calibrated within UAZ-2. A second analysis involved only 31 taxa from 31 sections with species of four genera (Borinella, Scythogondolella, Paulella and Wapitiodus) removed. This analysis therefore was dominated by species of Neospathodus and Novispathodus that have wide distribution and normally are applied to define the IOB; this analysis only yielded 10 unitary associations with UAZ-2 including species normally considered for defining the IOB. Unitary association analyses are deterministic, providing a single result for a given dataset, but are also very conservative by defining zones based on maximal associations of taxa rather than taxonomic events. As such they cannot define a GSSP, although they can constrain a GSSP-bearing interval. Two sections are currently considered as the candidates for the base-Olenekian GSSP, including the West Pingdingshan section of Chaohu area, Anhui Province, South China and the Mud section near Spiti, northern India. This unitary association analysis indicates that the West Pingdingshan section is the most complete and reproducible site for the GSSP of the IOB based on the first appearances of Eurygnathodus costatus, Neospathodus posterolongatus, Novispathodus waageni eowaageni, and Nv. waageni waageni. They all co-occur in UAZ-2, which is calibrated to a 5 m interval from Beds 23–4 to 25–30 at the West Pingdingshan section, in which the primary markers Nv. waageni eowaageni and Nv. waageni waageni do not appear until upper Bed 24 and lower Bed 25. The same UAZ is confined to Beds 12b to 14a in the Mud section. In addition, two new species: Neospathodus yangtzeensis sp. nov. and Novispathodus shani sp. nov. are described, which will significantly refine the conodont zonations of early-middle Smithian and help to constrain the IOB interval. Owing to global distribution, the well-documented Ns. posterolongatus may serve as an auxiliary marker for the IOB by its first occurrence (FO), and Eurygnathodus costatus approximates the IOB in shallow-water settings.

The Lutetian global stratotype section and point at Gorrondatxe revisited: Biomagnetostratigraphic refinements and astronomical tuning

Biomagnetostratigraphic studies carried out at the Ypresian/Lutetian (Eocene) Gorrondatxe section solved major chronostratigraphic calibration discrepancies that had existed for several decades. The new calibration resulted in the definition of the Global Stratotype Section and Point (GSSP) for the Lutetian Stage at the Gorrondatxe layer containing the lowest occurrence (LO) of the calcareous nannofossil Blackites inflatus (base of Subzone CP12b). However, subsequent studies cast some doubt on the reliability of the Gorrondatxe biomagnetostratigraphic data and, consequently, the appropriateness of the criterion used for the definition of the Lutetian GSSP. In order to address the issues raised, the biomagnetostratigraphy of the Gorrondatxe section was revisited and an additional cyclostratigraphic analysis was undertaken using magnetic susceptibility data series. The present study shows that the Gorrondatxe biomagnetostratigraphy is reliable. The spectral analyses showed the dominance of precession (∼20 ky) and short (∼100 ky) eccentricity forcing on sedimentation, but the influence of obliquity (∼38 and ∼ 55 ky) cycles was also detected and modulation by long (405 ky) eccentricity cycles was deduced. The succession was tuned to the 49.122–48.084 Ma interval and the astronomical ages obtained for a significant number of biomagnetostratigraphic events compared well with those derived from other studies. One of the exceptions is the LO of B. inflatus, which seems to be older in Gorrondatxe than in the Mediterranean and Western Atlantic areas. This diachrony most likely also delayed the LO of B. inflatus in historical reference sections of the North Sea area, rendering previous claims that the Lutetian GSSP caused some historical Lutetian sections to be Ypresian in age invalid. In fact, the definition of the base of the Lutetian Stage by the LO of B. inflatus at Gorrondatxe, now astronomically age dated at 48.455 Ma, best guarantees that the original concepts of the Ypresian and Lutetian historical stratotypes are maintained. Combined with secondary biomagnetostratigraphic marker events and an astronomically tuned cyclostratigraphy, the Ypresian/Lutetian Gorrondatxe section provides the globally significant chronostratigraphic reference model expected of any GSSP.

Global Stratotype Section and Point (GSSP) for the base-Artinskian Stage (Lower Permian)

Global Stratotype Section and Point (GSSP) for the base-Artinskian Stage (Lower Permian)

High-temperature combustion event spanning the Guadalupian−Lopingian boundary terminated by soil erosion

A major bio-crisis in the Guadalupian−Lopingian transition (Capitanian−Wuchiapingian, middle−late Permian), possibly driven by the volatile eruption of the Emeishan large igneous province (LIP), was marked by the first-order collapse of global metazoan reefs and decline of fusulinid foraminifera, but with only minor impacts on other marine invertebrates (brachiopod, crustacea, other foraminifera). To assess the exact cause of this event, we conducted geochemical analyses of the shallow marine strata at the global stratotype section and point of the Guadalupian−Lopingian (G−L) boundary (GLB) in Laibin, South China, which corresponds to the last step of the Capitanian bio-crises during Emeishan volcanism. Here, we detect evidence for high temperature combustion of organic matter in air spanning the GLB (indicated by enriched coronene) that was terminated by a soil erosion event accompanied with terrestrial vegetation collapse at the mass extinction level (evidenced by enriched dibenzofuran) and a carbon isotope perturbation (a 2.5–3.5‰ negative shift of δ13Ccarb). Molybdenum data indicates oxic seawater during the combustion event, likely reflecting regression. These findings imply that large volatile volcanic eruptions of the Emeishan LIP may have caused these environmental extreme events and mass extinctions, and that relatively lower magnitude of volcanism related to Emeishan LIP may have led to impacts on terrestrial−nearshore ecosystems.

Revisiting Early Jurassic Biscutaceae: Similiscutum giganteum sp. nov.

Abstract. A large, broadly elliptical coccolith of the genus Similiscutum (Biscutaceae) was observed in sediments dated from the Lower Jurassic (upper Pliensbachian to Toarcian) coming from different localities of western Tethys, namely Portugal (Lusitanian Basin), France (Causses and Paris basins) and Spain (Subbetic area). This form is quite easy to find in the Toarcian GSSP (Global Stratotype Section and Point) of Peniche (Portugal), where the holotype has been described. More than 100 specimens of Similiscutum were digitally captured using a CCD camera, including this large form and two other related species, Similiscutum finchii and Similiscutum novum. The length and width of the coccoliths and the length and width of their central area were measured, and biometric analyses were performed. Results show that this large morphotype of Similiscutum is well characterized and easily differentiable by its size and morphology from the species S. finchii and S. novum, which are characterized by a similar extinction pattern in optical-microscope crossed polars . On the basis of combined differences in size and in central-area shape and structure, Similiscutum giganteum sp. nov. is introduced here. (Plant Fossil Names Registry no.: PFN003067; Act LSID: urn:lsid:plantfossilnames.org:act:3067).

Integrated stratigraphical study of the Rhuddanian-Aeronian (Llandovery, Silurian) boundary succession in the Rheidol Gorge, Wales: a proposed Global Stratotype Section and Point for the base of the Aeronian Stage

Integrated stratigraphical study of the Rhuddanian-Aeronian (Llandovery, Silurian) boundary succession in the Rheidol Gorge, Wales: a proposed Global Stratotype Section and Point for the base of the Aeronian Stage

New Five Southern Tethyan Agglutinated Foraminiferal Species

Benthic foraminifera was studied as part of an investigation of the Dababiya section (Egypt), which was undertaken to document a candidate section for the Global Stratotype Section and Point (GSSP) for the base of the Ypresian Stage, Thanetian/Ypresian boundary, Late Campanian Dokan and Azmer sections of Kurdistan (NE Iraq), and the type section of Khangiran Formation of Khangiran section (NE Iran). Five new species of the genera Pseudogaudryina and Pseudogaudryinella are proposed, from three countries Egypt, Iraq and Iran, and from Campanian and Ypresian sediments. Three species of Pseudogaudryina: P. dababiyaensis (from Egypt), P. kurdistanensis and P. iraqensis (from Iraq), two species from Iran: Pseudogaudryinella iranica and Pseudoclavulina iranica. The Tethyan continental shelf fauna Midway-Type Fauna (MTF) of deep middle neritic to the upper bathyal environment is interpreted.

A short history of the Ordovician System: from overlapping unit stratotypes to global stratotype sections and points

Abstract The Ordovician System was introduced by Charles Lapworth as a solution to the overlapping unit stratotypes loosely defined by Adam Sedgwick, for the Cambrian, and Roderick Murchison, for the Silurian. The Ordovician has emerged as one of the longest and most significant of the geological periods. Following an interval of intensive research of all the key regions of the globe, unit stratotypes in the type areas of England and Wales have been replaced by seven global stages and three series based on Global Stratotype Sections and Points (GSSPs), enhancing the definition of these chronostratigraphic units and facilitating global correlation. As a consequence, the biological and geological events during the period can be recognized and the magnitude and significance of biotic originations and extinctions understood with some confidence.

Stratigraphy of the Cretaceous/Paleogene (K/Pg) boundary at the Global Stratotype Section and Point (GSSP) in El Kef, Tunisia: New insights from the El Kef Coring Project

The Cretaceous/Paleogene (K/Pg) boundary is marked by one of the largest mass extinctions in Earth’s history, with geological evidence for this event being expressed in hundreds of locations worldwide. An extensively studied section located near El Kef, northwestern Tunisia, is characterized by the classic iridium-rich K/Pg boundary layer, abundant and well-preserved microfossils, and apparently continuous sedimentation throughout the early Danian with no previously described structural complication. These features led to its designation in 1991 as the Global Stratigraphic Section and Point (GSSP) for the base of the Danian (i.e., the K/Pg boundary). However, the outcrop section has become weathered, and the “golden spike” marking the GSSP is difficult to locate. Therefore, the El Kef Coring Project aimed to provide a continuous record of unweathered sediments across the K/Pg transition in cores recovered from five rotary-drilled holes located close to the El Kef GSSP. Here, we present new, high-resolution lithologic, biostratigraphic, and geochemical data from these cores. The recovered stratigraphic successions of each hole (all drilled within ∼75 m of one another) are unexpectedly different, and we identified a formerly unknown unconformity within planktic foraminiferal biozone P1b. Our results provide evidence that sedimentation at El Kef was not as continuous or free from structural complication as previously thought. Despite these challenges, we present a new composite section from the five El Kef holes and an age model correlated to the orbitally tuned record at Walvis Ridge, South Atlantic Ocean, which is critical in placing the paleoenvironmental and paleoecological records from El Kef in a global context.