Sequence Stratigraphy Research Articles

Prediction of Thin Shoal Reservoirs Under Reef Controlled by Isochronous Stratigraphic Framework

Despite the great success in the global exploration and development of reef reservoirs, research on bioclastic shoals under reefs is still in its infancy. Bioclastic shoal reservoirs are very thin, with multiple vertical levels and fast lateral changes, which makes accurate prediction of the reservoir’s location much tougher. To further implement the reservoir distribution, under the guidance of sequence stratigraphy, the prediction of thin shoals under the control of an isochronous stratigraphic framework was established. Using the combination of spectrum shaping and F-X domain noise suppression techniques and utilizing the signal-to-noise ratio spectrum set as the reference, logging curve as supervision, and well seismic calibration and isochronal amplitude slicing as quality control, the seismic frequency band was extended, and the seismic data resolution and signal-to-noise ratio were improved. After frequency extension, the global optimal seismic automatic interpretation technique was used to construct an isochronal stratigraphic framework model. Through waveform facies-controlled inversion and waveform facies-controlled simulation techniques, the elastic properties of the shoal reservoir were obtained, from which the planar distribution of the reservoir was accurately predicted. The above methods were applied to the prediction of the bioclastic shoal reservoir in the lower submember of the Changxing formation in the Yuanba gas field (China). The plane distribution of bioclastic shoal in the first and second levels was identified, which provides a guideline for the prediction of thin shoal reservoirs.

Metallogenic model of sandstone-hosted copper deposits: A case study from the Paleogene in Jiashi area, northwestern China

Sandstone-hosted copper deposits, a type of Sediment-Hosted Stratiform Copper (SSC) deposits, are widely distributed globally. While economically viable deposits of SSC are relatively scarce, they account for approximately 30 % of the world's total discovered copper resources. However, there is still a lack of comprehensive and in-depth research into the depositional and metallogenic models of these deposits. The Jiashi area of the Tarim Basin in northwestern China, known for its economically significant Paleogene SSC deposit, lacks in-depth studies on metallogenic processes. To address this, field profile observations were conducted to analyze the sedimentary evolution, sequence stratigraphy, and tectonism of the Paleogene strata in the Jiashi area. Combined with elemental geochemical analysis of samples, the provenance of sediment, and the source of metallogenic materials, a robust metallogenic model was established. The results reveal the influence of provenance for the origin of Paleogene copper-rich strata. Sedimentary evolution played a crucial role in controlling the distribution of copper and sulfur elements, as well as the spatial arrangement of metallogenic beds. Additionally, nappe movement potentially generated faults, allowing upward movement of basin fluids, which played a crucial role in the formation of copper deposits within sandstone-hosted systems. Thus, this study offers a comprehensive analysis of the metallogenic processes involved in sandstone-hosted copper deposits, thereby contributing significant insights to the broader research on SSC deposits worldwide.

Analysis of lake level fluctuations in the Early Cretaceous Songliao Basin supports aquifer eustacy

Clear geochronology and precise interpretation of sequence stratigraphy enhance our understanding of continental lake-level evolution. The Songliao Basin features well-preserved Cretaceous continental strata. Nevertheless, the correlation between lake-level fluctuations and global sea-level changes remains ambiguous. High-resolution gamma ray logging data were used to analyze the cyclical stratigraphy of the lower member of the Early Cretaceous Shahezi Formation in the Songliao Basin. X-ray fluorescence experiments characterized the sedimentary environment of this formation. Lake-level variations in the lower part of the Early Cretaceous Shahezi Formation were reconstructed using sedimentary noise modeling based on finely tuned gamma ray logging data. Time series analysis using the tuned gamma ray data established an astronomical timescale of approximately 2.4 Myr within the lower section of the early Cretaceous Shahezi Formation in the Songliao Basin. A volcanic ash layer dating (118.20 ± 1.5) Ma from the base of the Shahezi Formation served as an anchor point, providing an absolute astronomical timescale ranging from 115.80 to 118.20 Ma for the study region. The sedimentary model indicates that variations in paleowater depth within the lower section of the Shahezi Formation closely match fluctuations observed in the Fe/Mn index, which reflects paleowater depth changes. This introduces a novel approach to assess changes in continental lake levels. The sedimentary noise model revealed a notable obliquity cycle of about 1.2 million years, strongly associated with fluctuations in lake levels. This indicates that prolonged obliquity periods affect lake level variations. Intriguingly, when lake levels rise, global sea levels concurrently decline, highlighting an inverse relationship between these phenomena. This observation offers insights into how long-term obliquity-driven climate changes regulate sea and lake levels.

Exploring the Dynamic Interactions Between the Southern San Andreas Fault and a Normal Fault Under the Salton Sea

AbstractWe investigate the dynamic interactions between the Southern San Andreas Fault (SSAF) and a proximal normal fault (NF) beneath the Salton Sea in southern California. The NF, positioned near the SSAF terminus at Bombay Beach, exhibits 11–15 displacement events across 14 stratigraphic sequences, with a range of 0.2–1.4 m of vertical offset since ∼2–3 ka. Notably, four of these events may align temporally with SSAF earthquakes, raising questions about the possible interplay between the two faults. Utilizing dynamic rupture models, we analyze the coseismic interactions between the SSAF and NF, addressing under what conditions the SSAF induces slip on the NF. Our findings reveal that a suite of SSAF ruptures, particularly those propagating from north to south, can trigger slip on the normal fault and replicate observed vertical offsets. If the SSAF extends beneath the Salton Sea, earthquakes originating south of the NF intersection are less likely to trigger normal fault slip, although we cannot exclude this possibility. Some SSAF ruptures do not trigger discernible slip on the NF, rendering such events undetectable in the stratigraphic record. Our research contributes toward discussions regarding the seismic hazard in southern California, shedding light on the interplay between the SSAF and NF.

Cretaceous stratigraphy in the Songliao Basin, NE China

The Songliao Basin is one of the largest non-marine oil- and gas-bearing basins that developed during the Cretaceous period, recording an almost complete Cretaceous stratigraphy. With oil and gas exploration, as well as the Continental Scientific Drilling Project of Cretaceous Songliao Basin (CCSD-SK) (2006–21), significant progress has been made on the stratigraphy of the Songliao Basin. The Songliao Basin is therefore important for understanding the non-marine Cretaceous system. Based on lithostratigraphy, sequence stratigraphy, biostratigraphy, geochronology, magnetostratigraphy and cyclostratigraphy, a comprehensive stratigraphical framework of the Songliao Basin has been established in this study. The Lower Cretaceous strata (Hauterivian–Albian) of the basin are dominated by volcanic–sedimentary deposits, while the lower-middle Upper Cretaceous (Cenomanian mid-Campanian) strata are dominated by lacustrine deposits. The upper Upper Cretaceous strata (late Campanian–Maastrichtian) are dominated by fluvial–lacustrine deposits. Fossils are very abundant in the Songliao Basin, and three biotas – the Jehol Biota sensu lato , the Songhuajiang Biota and the Mingshui Biota – are recognized in the Songliao Basin. Furthermore, several important geological events, such as lake anoxic events, seawater incursion events and the K/Pg boundary extinction events are all recorded in the Songliao Basin.

New Cingulata (Mammalia, Xenarthra) from the late Neogene Palo Pintado Formation (Northwestern Argentina)

Cingulata (Early Eocene-Recent) is a very well-diversified clade that reached a high diversity during the early Neogene. In southern South America, there is an evident imbalance in our knowledge of the Neogene diversity along the Northwestern region of Argentina (NWA) compared to the Pampean region (PR), despite the importance of NWA to understanding the hypothetical evolutionary scenarios of several clades. The Palo Pintado Formation (ca. 10–5 Ma) is one of the richest units in NWA, involving both the global warming of the Tortonian (ca. 11.6–7.25 Ma) and the global cooling event of the Messinian (ca. 7.25–5.33), coeval with the widespread of the C4 plants. Despite this, Cingulata from this Formation are still poorly known. Interdisciplinary fieldwork at Calchaqui Valley (Angastaco Basin) yielded several new remains, including Chlamyphoridae Euphractinae Proeuphractus limpidus, Chorobates villossisimus and Prozaedyus sp.; Dasypodidae Dasypus sp.; Pampatheriidae Kraglievichia paranensis; and Glyptodontidae Cranithlastus xibiensis. The “armadillos” P. limpidus, Prozaedyus sp., and Dasypus sp. increase the previously known diversity. The record of Dasypus sp. reinforces recent hypotheses extending the biochron of the genus to the Late Miocene in NWA. The recognized taxonomic diversity of glyptodonts, limited to one species, contrasts with that known from other coeval formations placed both in the south (Andalhuala and Corral Quemado formations, Catamarca Province) and the north (Maimará and Tafna formations, Jujuy Province), revealing a complex biogeographic scenario for this clade during this period. The analyzed deposits are interpreted as accumulated within the channel and formed during episodes of large discharges of water and sediment mostly under a warm subtropical climate, tough there is an aridization recorded at ca. 6 Ma, which is probably related to the increase in the taxonomic diversification of Cingulata along the stratigraphic sequence.

Development of a PCR assay for rapid and accurate detection of an emerging vanB Enterococcus faecium clone in the Capital Region of Denmark

Abstract Objectives To develop and validate a real-time PCR assay detecting the sequence bridging Tn1549 and the Enterococcus faecium chromosome in the emerging vanB vancomycin-resistant E. faecium (VREfm) clone (ST80/CT2406). Methods The Tn1549 insertion site was determined on routinely sequenced VREfm isolates. The outer boundaries of Tn1549 and adjoining host bacterial sequences were determined using a BLAST search in the silent information regulator gene sir2. Next, the primers and probe were developed, targeting the sequence bridging Tn1549 and the E. faecium chromosome. Finally, the PCR assay was validated on well-characterized strains and prospectively performed on rectal screening samples submitted to our laboratory. Results and conclusions The PCR assay proved to be accurate and provide rapid diagnosis of the emerging vanB VREfm in rectal screening samples.

Miocene bioerosion in a Cretaceous metamorphic basement from the Arzew Mountains (Oran, northwestern Algeria): First evidence of a Tortonian rocky shore in the southwestern Mediterranean area

Bioerosive trace fossils at the Guessiba Valley (Arzew Mountains) document an ancient Tortonian shoreline cut into Barremian calcschists at the lowermost part of the Tortonian Balanid Marl Formation. Four ichnogenera produced by endolithic bivalves (Gastrochaenolites) and polychaete annelids (Caulostrepsis, Maeandropolydora, Trypanites) have been identified. The four traces consist of dwelling structures (domichnia). The encrusting epifauna on the rockground include acorn barnacles of the genus Balanus and scarce, poorly preserved bivalves. These epibionts exhibit Trypanites and Entobia, respectively. This ichnoassociation identifies the Entobia ichnosubfacies as part of the Trypanites ichnofacies. The fossil rocky shore described in this paper is related to a transgression that occurred during the Tortonian, characterising a stratigraphic surface corresponding to a sequence boundary. The Guessiba Valley succession marks the first Mediterranean marine transgression affecting the southern flank of the Arzew Mountains, characterised by three distinct phases. The calcschists reported here are among the rare examples of non-carbonate rocky substrates colonised by endolithic boring organisms.

A conceptual and numerical model of fluid flow and heat transport in the Topusko hydrothermal system

Comprehensive understanding of hydrothermal systems is often obtained through the integration of conceptual and numerical modelling. This integrated approach provides a structured framework for the reconstruction and quantification of fluid dynamics in the reservoir, thereby facilitating informed decision-making for sustainable utilisation and environmental protection of the hydrothermal system. In this study, an updated conceptual model of the Topusko hydrothermal system (THS; central Croatia) is proposed based on structural, geochemical, and hydrogeological analyses. The stratigraphic sequence and the structural framework of the THS were defined based on geological maps and field investigations. As depicted by hydrochemical and isotope analyses, thermal waters in Topusko (temperatures of up to 65 °C) are of meteoric origin and circulate in a carbonate aquifer. The THS receives diffuse recharge approximately 13 km S from Topusko, where Triassic carbonates crop out. Gravity-driven regional groundwater circulation is favoured by regional thrusts that tectonically uplifted Palaeozoic low permeable rocks. These structures confine the fluid flow in the permeable, fractured and karstified, Triassic carbonates favouring the northward circulation of the water. A regional anticline lifts the aquifer closer to the surface in Topusko. Open fractures in the anticline hinge zone increase the fracturing and permeability field of the aquifer promoting the quick upwelling of the thermal water resulting in the Topusko thermal springs. Numerical simulations of fluid flow and heat transport corroborate the proposed conceptual model. In particular, a thermal anomaly was modelled in the Topusko subsurface with temperature values of 31.3 °C and 59.5 °C at the surface and at the base of the thermal aquifer, respectively, approaching the field observations. These findings showed that the circulation of Topusko thermal water is influenced by regional and local geological structures suggesting that the enhanced permeability field in the discharge area enables the formation of the natural thermal springs.

Relocate the base of the Arundian? A re-evaluation from south Cumbrian sections and implications for British and Irish Lower Carboniferous successions

The largely ice-free world of the ‘Chadian’–Arundian (early Visean) is investigated in two successions in south Cumbria to better understand the relationships between transgression, hiatus and the position of the basal Arundian. A detailed foraminiferal biostratigraphy is used to age-constrain the transition from the late ‘Chadian’ to early Arundian. This demonstrates a good synchronous relationship between the sequence stratigraphy of the two successions and the first occurrence of key species (mostly primitive archaediscids, rapidly followed by more evolved forms of the same family), suggesting that there is no significant hiatus and that the record of faunal changes is closely comparable in the key successions. A synthesis of other ‘Chadian’–Arundian boundary successions in Britain and Ireland indicates some key problems with the current Arundian boundary stratotype in practical usage. We propose a stratigraphically higher position for the Arundian boundary in the stratotype, which is more easily correlated to the Bobrikian and Moliniacian substages of eastern Europe and Belgium, respectively, and tied to the first occurrences of foraminifera species, allowing more robust age assessments, free from the confounding factors of inferred lithological or sequence stratigraphic changes.

Structural evolution of the Handun salt diapir, Zagros fold and thrust belt, southern Iran

The Fars region, in the Zagros fold and thrust belt, hosts a wide range of diapirs piercing over 10 km of stratigraphic sequence. Comprising Precambrian to Early-Cambrian Hormuz Salt, these diapirs exhibit a prolonged history of evolution. Outcrop evidence for understanding the diapir deformation history is mostly limited to the Cenozoic contractive phase, and the seismic data lacks the necessary quality for an exhaustive understanding of the deepest structure's geometries. Through regional and field evidence we unravel the Handun salt structure evolution and propose a sequential restoration to describe the key deformational events. Our study presents a field-based novel regional balanced cross-section and a 3D-geological model, and addresses the role of structural inheritances and the position of the Handun diapir with respect to the decupled basement. The performed field studies describe folds and unconformities related to Cenozoic halokinetic sequences with exceptional clarity. It was possible to observe changes of the diapir activity along the structure and provide field evidence for the relative timing and kinematics of primary and secondary welding. Finally, our data suggest that the Handun diapir formed in the early Paleozoic above the shoulder of a basement extensional fault, and was partially translated above its southern hanging-wall during the shortening. In the Paleocene a sustained ratio of salt rise rate was enhanced by the Zagros/Oman contraction. In response to the Oligocene continental collision, the diapir was profusely supplied with salt, which flared upward to form overhangs. Since the middle Miocene the salt supply slowly depleted, with the diapiric walls remaining near the surface but tapering upward, probably due to primary welding or increased sedimentation. Secondary welding occurred post-Pliocene in the last stages of the diapir evolution with consequent development of a secondary minibasin.

To date or not to date? A comparison of different 14C pretreatment methods applied to archeological marine shells from Vale Boi (Portugal)

Abstract Mollusk shells are often found in archeological sites, given their great preservation potential and high value as a multipurpose resource, and they can often be the only available materials useful for radiocarbon (14C) dating. However, dates obtained from shells are often regarded as less reliable compared to those from bones, wood, or charcoals due to different factors (e.g., Isotope fractionation, reservoir effects etc.). The standard acid etching pretreatment for mollusk shells is the most used in many 14C laboratories, although another protocol known as CarDS (Carbonate Density Separation) was introduced just over a decade ago. We compare these two methods with two newly proposed methods for intracellular organic matrix extraction. We applied all four methods to samples selected from different archeological layers of the well-known Upper Paleolithic site of Vale Boi, rich in mollusk specimens throughout the stratigraphic sequence. Here we compare our results to previous dates to determine which of these pretreatment methods results in the most reliable 14C dates. Based on the results of this study, all four methods gave inconsistent ages compared to previous dates and the stratigraphic attribution.

Paleoenvironmental reconstruction of coal deposition during the Cretaceous-Paleogene transition in the Eastern Cordillera Basin, Colombian Andes

Stratal stacking patterns and factors influencing peat accumulation in coastal and continental settings represent a significant problem in studying coal-bearing sequences. To address this issue, this work focused on the Cretaceous-Paleogene Guaduas Formation on the Checua-Lenguazaque Syncline (CLS) coalfield in the Eastern Cordillera Basin (Colombian Andes). This study relies on geological survey, facies analysis, sequence stratigraphy, organic geochemistry, and coal petrography. Through these methods, depositional systems and sequences were characterized, and their relationship with coal composition was established. Sedimentary facies were categorized into four Facies Associations (FAs): lagoon, tidal flat, delta plain, and mixed fluvial system. Five T-R sequences (S1 to S5, in ascending order) were identified. S1 consists of lagoon and tidal sandstone, mudstone, and coal. S2-S4 comprise tidal, deltaic, and fluvial deposits. S5 is composed mainly of deltaic and fluvial facies. Thick coal seams (> 0.7 m) were concentrated in the regressive system tracts of S1 and S3, while the transgressive coals were deposited in S2-S3 and are associated with tidal environments. The organic petrography showed enrichment in vitrinite (30.00–85.20 %), while liptinite (0.00–16.60 %) and inertinite (4.60–34.40 %) varied according to depth and paleoenvironments. CLS coalfield displays an environmental evolution from shallow marine and lagoon deposits to deltaic and fluvial environments. Minor sea-level fluctuations, changes in accommodation, siliciclastic influx, and plant community distinguish this sedimentary succession. The deposition of the Guaduas Formation is characterized by a prograding pattern with dominant shallowing-upward cycles in a high accommodation setting. The organic matter accumulated under limno-telmatic to telmatic conditions in mesotrophic to ombrotrophic environments with nutrients derived mainly from rainfall. The paleoclimate for the Guaduas Formation indicates wet and hot conditions for flora expansion. This investigation determined paleoenvironments of the Maastrichtian-Paleocene coastal to fluvial successions within the tropical latitudes, indicating a strong relationship between depositional systems, sequence stratigraphy, paleoclimate, and coal composition.

Carbon isotopic record of a platform-to-basin transect through the Permian Reef Complex (Guadalupian) in the Delaware Basin of Texas and New Mexico

The Guadalupian Permian Reef Complex of the Delaware Basin is one of the most studied carbonate reef systems of the Paleozoic. Despite extensive work on the carbonate sedimentology, sequence stratigraphy, and diagenetic history of the Delaware Basin, a high-resolution carbonate carbon isotope record along a platform to basin transect for the Capitanian (264.3–259.5 Ma, the youngest age of the Guadalupian Epoch) does not yet exist. The carbon isotopic record of the Delaware Basin is important because 1) it allows us to test hypotheses about controls on the carbon isotope proxy, 2) it provides constraints on how well modern carbonate platforms like the Great Bahama Banks serve as analogues for ancient carbonate settings, and 3) these types of restricted basins likely played an important role in Permian carbon cycling and the Capitanian extinctions.In this study we present 493 new Capitanian carbonate carbon isotopic values paired with a detailed sedimentological and sequence stratigraphic framework from the platform, slope, toe of slope, and deep basin of the Delaware Basin. The bulk of the new δ13C values fall within the range of previously reported unaltered carbonates from the basin, suggesting that these results record primary environmental processes and were not significantly altered by diagenetic overprinting. With this dataset, we test hypotheses about sources of carbon isotopic variability in shallow carbonate platforms. Our results indicate that in the Delaware Basin there are no systematic and resolvable depth or lateral gradients in carbon isotopic values, that δ13C values do not vary as a function of grain type, and that there is no resolvable relationship between carbon isotopic composition and sea level change. However, we do document statistically significant differences in δ13C distributions among facies associations which we attribute to the isotopic evolution of an upwelling water mass due to direct precipitation of mud along the slope. Our results support the idea that increasing carbon isotopic values through the Capitanian were driven by increased organic carbon burial in restricted basins.

Generating more constrained seeds for seismic horizon extraction

Enhancing accuracy remains the main challenge for the current horizon extraction algorithms. Adding more manually interpreted seeds helps to improve the accuracy of horizon extraction. We intend to generate more seeds prior to the 3D horizon extraction based on seeds that are manually interpreted on the coarse grid of the seismic survey. First, we compute four horizons for the same seismic sequence boundary using deep learning and constrained least-squares algorithms under the constraints of manually interpreted horizon seeds. Next, we generate more seeds by checking the consistency among those four horizons for each seismic trace, and this process is implemented in the same way as the tying loops of manual horizon interpretation. Finally, we extract horizons using constrained least-squares algorithms with the newly computed seeds. The applications of two real seismic surveys demonstrate that our method can generate horizons with higher accuracy when compared with the horizons computed with only manually interpreted seeds.

Revisiting the Late Bronze Age stratigraphy of Tel Lachish

This study investigates the stratigraphy of Tel Lachish during the Late Bronze Age. For a variety of reasons, a certain degree of confusion and disorder in the understanding of the stratigraphical sequence of this period has accumulated throughout the long-term research of the site, leading, consequently, to a distraction in the understanding of the site’s history. This study discusses these problems, examines the local stratigraphy in the various excavation areas, and proposes a new general division of the site’s history during the Late Bronze Age based on general horizons.

Intra-tooth isotopic analysis shows seasonal variability in the high-elevation context of Melka Kunture (Upper Awash Valley, Ethiopia) during the Early Pleistocene

In order to investigate seasonal changes in diet, environment and climate, we analyzed the stable carbon and oxygen isotopic composition of intra-tooth sequential profiles (14 teeth, 282 enamel samples) of Hippopotamidae, Equidae, Bovidae and Suidae from Melka Kunture, Upper Awash Valley, central Ethiopian Highlands (2000–2200 m a.s.l.).We found that during the Early Pleistocene, between 1.95 and 1 Ma, most of the analyzed hippos display a seasonally stable C4 diet, even if the δ13C values within hippos show a degree of variability that we interpret as the outcome of feeding on plants that use different C4 photosynthetic pathways. Several hippo specimens display a seasonal shift from C4 to mixed C3-C4 diets. The sampled equid, bovid and suid specimens recorded both stable C4 diets and mixed C3-C4 feeding with a seasonal progressive increase of δ13C values. When affected by seasonal changes, the serially analyzed taxa show different niche partitioning: hippos increase the consumption of C3 vegetation, whereas equids and suids include more C4 vegetation in their diets. The intra-individual δ18O variability in the analyzed taxa is interpreted as the outcome of different water sources, depending on animal habitat, behavior and mobility patterns.Our data are placed in controlled stratigraphic and chronological sequences and combined with the outcome of other proxies, allowing us to evaluate the site paleoecology comprehensively. We suggest that the central Ethiopian Highlands, where MK is located, possibly acted as a refugium-like area during the Early and Middle Pleistocene, characterized by a specific type of montane vegetation (DAF) and diverse faunal and hominin species that demonstrated their resilience and adaptability to changing environments and climates.

Evolution and hydro-stratigraphy of the coastal aquifer in Garopaba/SC: Interpretation from georadar and tubular wells

This work analyzes the geological evolution of sedimentary deposits in the coastal aquifer of Garopaba, south Brazil, using ground penetrating radar (GPR) and data from tubular wells. The aquifer is localized in the coastal plain, where Quaternary lagoon-barrier environments are set between the Precambrian crystalline mountains and the sea. Over ten tubular wells are scattered in urbanized areas, which highlights the vulnerability of the unconfined, granular shallow aquifer. The results show that the aquifer has lithologic units of local scale. Tubular well data show the basal limit of the aquifer overlying clayey layers between 30 and 40 m deep and intercalation of sand layers up to the surface, mostly fine to very fine sand, with metric thickness, secondary lenses of clay and minor occurrence of gravel. The radarfacies interpretation shows fluvial-estuarine deposits as a local hydrostratigraphic unit, with lateral accretion bars filling a NE-axis paleochannel. The basal surface of the channel is interpreted as the sequence boundary surface of the lagoon-barrier systems III (upper Pleistocene) and IV (Holocene). The geological evolution of the aquifer is related to the upper Pleistocene marine regression (120–18 ka), that caused the aerial exposure of the continental shelf, and the development of complex drainage channels, which were superimposed during the Holocene transgression by lagoon-barrier IV deposits. After the post-glacial transgression, the lowering of the RSL to the current level promoted the silting of part of the lagoon system by continental sedimentation and aeolian deposits composing the surface.

Late Middle Pleistocene (MIS 11‐6) in Europe – introduction

The following collection of contributions presents both unique and synthesized regional evidence that provides considerable clarification regarding this part of the European Quaternary stratigraphical sequence. It is a reliable step forward to overcome an over‐simplistic view, because progress over recent years in many different fields has led to significant advances in our understanding regarding the interactions between environmental processes and climate.

Comprehensive Basin Analysis and Petroleum Potential Evaluation of Ayoluengo Oil Field, Basque-Cantabrian Basin, Spain

This study presents a comprehensive basin analysis and petroleum potential evaluation of the Ayoluengo oil field in the Basque-Cantabrian Basin, Spain. Using an integrated approach combining geological, geophysical, and geochemical data, we analyzed the basin's evolution and petroleum system elements. The dataset included 2D and 3D seismic data, well logs, formation tops, and geophysical maps. Our analysis revealed a complex structural framework characterized by salt diapirism and halokinetic structures. Well log interpretation and sequence stratigraphic analysis identified two genetic sequences with associated systems tracts. Four reservoir units were mapped, with the main structural traps related to salt diapirs. Seismic facies analysis highlighted high-amplitude convergent (CBH) and high- and low-amplitude convergent (CBHL) facies as the most promising for reservoir quality. The study identified one play (Jurassic) and two prospects: Lias Limestone (80% geologic chance of success) and Carniolas Dolomite (85% geologic chance of success). Volumetric calculations estimate significant hydrocarbon potential, with STOIIP (Stock Tank Oil Initially In Place) ranging from 3.4 to 4.2 x 10^16 barrels for the Lias Limestone reservoir and 1.26 to 1.56 x 10^16 barrels for the Carniolas Dolomite reservoir.