3D anatomy of the Cretaceous-Paleogene age Nadir Crater

doi:10.21203/rs.3.rs-4363378/v1

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3D anatomy of the Cretaceous-Paleogene age Nadir Crater

https://doi.org/10.21203/rs.3.rs-4363378/v1

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published 03 Oct, 2024

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The Nadir Crater offshore West Africa is a recently proposed near K-Pg impact structure identified on 2D seismic. Here we present 3D seismic data that image this crater in exceptional detail, unprecedented for any such structure, which demonstrates beyond reasonable doubt that the crater-forming mechanism was a hypervelocity impact. Seismic mapping reveals a near-circular crater rim of 9.2 km and an outer brim of ~23 km diameter defined by concentric normal faults. An extended damage zone is evident across the region, well beyond the perceived limit of subsurface deformation for impact craters, except in a ‘sheltered zone’ to the east. The seabed shows evidence for widespread liquefaction because of seismic shaking and scars and gullies formed by tsunami wave propagation and resurge. Deformation within the ~425 m high stratigraphic uplift and annular moat allow us to reconstruct the evolution of the crater, with radial thrusts at the periphery of the uplift suggesting a low-angle impact from the east. Structural relationships allow us to reconstruct the deformation processes during the crater modification stage, with the central uplift forming first, followed by centripetal flow of surrounding sediments into the evacuated crater floor in the seconds to minutes after impact.

Earth and environmental sciences/Planetary science/Meteoritics

Earth and environmental sciences/Natural hazards

3D seismic reveal the anatomy of the Nadir Crater in exceptional detail, allowing us to reconstruct a marine-target impact event.

The Nadir Crater is a proposed hypervelocity impact structure of approximately Cretaceous-Paleogene (K-Pg) boundary age (66 Ma) ¹. The similarity in age of the crater with the 200 km Chicxulub crater in Mexico ^2,3, has led to the suggestion that the end-Cretaceous extinction event may have been associated with more than one impact – either break-up of a parent asteroid in near-Earth orbit, or as part of a longer lived (~1-2 My) temporal cluster of impacts ¹. The Nadir Crater has only previously been imaged on two individual 2D seismic profiles, which show characteristics consistent with a complex, mid-sized (≥8.5 km diameter) crater, including a pronounced ≥350 m central uplift below the crater floor and large-offset listric normal faults in the annular moat and below the topographic crater rim ¹. The 2D data also allowed the identification of a wide zone of shallow normal faults that extends around two crater radii either side of the crater, interpreted as a damage zone defining the surface “brim”. However, it is not clear from these limited data whether the crater rim or brim are truly circular (or near circular), and what the spatial variability is of the deformation features both inside and outside of the crater rim. In addition, it is evident from deep seismic artefacts that the seismic processing velocities for the crater in these regional 2D seismic profiles are too low, resulting in poor seismic imaging in the shallow subsurface, particularly around the central uplift.

Although other, epigenetic, mechanisms for crater formation are considered unlikely for the Nadir Crater, uncertainty over a hypervelocity impact origin remains because of the limited data coverage previously published and absence of geological samples ¹. In this paper, we present recently acquired 3D seismic data across the Nadir Crater that allows us to image the surface morphology and subsurface deformation of this pristine crater in exceptional detail. The seismic data cover an area of ~2500 km², (50 km x 50 km), extending >20 km beyond the crater rim in all directions (Fig. 1). These data provide compelling evidence for an impact origin, and an unprecedented opportunity to image the surface and subsurface characteristics of an impact crater in 3D and to test and construct new models of crater development in marine targets.

The Nadir Crater is located offshore Republic of Guinea in West Africa, on the Guinea Plateau, at a water depth of 900 m (Fig. 1). The Guinea Plateau is an extended continental promontory that formed after the breakup of North America and Africa in the Middle-Late Jurassic ²¹ and then South America and Africa in the Aptian-Albian ²². The stratigraphy of the Guinea Terrace is constrained by seismic correlation from industry boreholes on the southeast of the Guinea Plateau, where a thick Early Cretaceous to Recent sequence has been drilled ^18,22,23. The stratigraphic sequence consists of a thick package of sedimentary rocks, with up to 8 km of Jurassic to Early Cretaceous carbonates and clastics sitting above volcanic basement. These are overlain by a ~ 2–3 km thick sequence of Aptian to lower Albian clastics that are deformed by normal and transtensional faults. An erosional unconformity separates this sequence from the overlying Albian-Recent sequence that consists predominantly of marine clastic sediments ^18,23 deposited in a tectonically quiescent, passive margin.

The crater is located 300 m below the seabed approximately at the K-Pg boundary ¹⁸. The water depth at the time of proposed impact was likely around 800 m, based on seismic analysis of Maastrichtian clinoform heights and numerical modelling results ¹⁸. The Cretaceous-Recent sequence in which the Nadir Crater is located was deposited on a nearly horizontal seafloor (< 1° slope) on the Guinea Terrace, an important consideration for the environmental setting during its formation.

Seismic velocity structure of the crater

Seismic velocities from the pre-stack depth-migrated 3D seismic provide important information on the velocity structure of the crater and target stratigraphy, extending to the base of the stratigraphic sequence (Fig. 2). Velocities increase from around 1500 m/s at the seabed to around 1900 m/s at the top of the Cretaceous (K-Pg). Outside of the crater, and in the annular moat, velocities increase at a consistent rate of around 1000 m/s per km (Fig. 2B). However, relative to stratigraphically equivalent velocities, these are elevated in the central uplift below the crater floor, up to a maximum of 500 m/s higher. Assuming that this velocity effect is primarily due to a reduction in porosity (and corresponding increase in bulk density), this likely corresponds to a 10-15% reduction in porosity in the target stratigraphy in the central uplift ⁷.

This velocity anomaly extends vertically to around 3 km depth (~1.8 km below the crater floor), below which there is no obvious difference from the surrounding velocity structure. There is also no stratigraphic uplift evident at the bright reflectors at ~4 km depth, confirming that the apparent uplift of strata at and below this depth in older 2D data ¹ is a seismic ‘pull-up’ effect; a processing artefact from the regional 2D velocity model.

Planform morphology of the crater and contemporaneous seabed

The seismic depth map and derived attribute maps of the inferred K-Pg surfaces reveal a near-circular crater, with a rim diameter ⁸ of ~9.2 km, and an area of ~67 km² (Fig. 3). The crater planform displays some degree of polygonality, with more linear segments on the northeast and southwest sides. The crater is surrounded by a zone of well-developed concentric features, corresponding to concentric normal faults in the shallow subsurface. The surface (K-Pg) expression of these is used to define the crater brim, which has a diameter of ~22-24 km. The crater surface also displays a clear central peak and terraces within the rim, evident on all three mapped horizons that constitute the expanded K-Pg boundary sequence within the crater (Fig. S1). The central peak has a relief of 40 m at the KPg1 horizon, 20 m at the KPg2 horizon and only 10 m at the KPg3 horizon.

The area outside of the topographic crater rim also shows distinctive geomorphological features. There is an arcuate feature evident to the east of the crater (Fig. 3) with a concave-to-the-west geometry that we interpret as a resurge scar ⁹. High-variance (discontinuous amplitude) facies to the southwest of the crater have a distributive, fan-like morphology expanding away from the crater rim, that we interpret as outwash deposits from the crater. The highest amplitudes at the KPg3 horizon are distributed to the south and west of the crater, possibly indicating the area of thickest ejecta deposits or tsunami-reworked deposits ¹.

However, there are also subtle concentric ridges outside of the crater rim, particularly in the north of the seismic volume (Fig. 3). These ridges appear to be formed by irregularities in the extensive underlying chaotic unit that extends far beyond the seismic data, and across much of the Guinea Terrace, previously interpreted as a possible reworked tsunamite layer ¹.

Subsurface deformation structures

The structural deformation evident in the subsurface within the ~22-24 km diameter crater brim is more complex in the 3D seismic data than observed from the previous 2D profiles and varies substantially with increasing depth below the K-Pg surface (Fig. 4). At the shallowest continuously mapped surface, KU3, which would have originally been around ~100-150 m below the pre-impact seabed, deformation is dominated by intense folding and faulting in the central uplift, reverse faults within the annular moat, and normal faults in the wider brim. The larger-offset, planar faults to the northeast are clearly linked to underlying normal faults in the Aptian sequence (Fig. 4C, D, E). Extensional duplexes form southwest and northeast of the crater (Fig. 4A, B). Deformation at this shallow level is not limited to faulting. Complex folds are evident in the shallow stratigraphy, with those in the periphery of the central uplift displaying a tight, isoclinal character, and are even overturned in places. The most intensely folded sequences are associated with thickening of the target stratigraphy towards the crater floor (Fig. 4E).

At deeper stratigraphic levels, from KU2 (originally 500 m below the pre-impact seabed) and below, a well-developed annular moat and central uplift are evident (Fig. 4B). At the KU1 and KU0 level (~700 and ~900 m below the pre-impact seabed; Fig. 4C and 4D respectively), deformation is mainly limited to the annular moat and central uplift, with little evidence for deformation up to and beyond the brim. This suggests that the extension dominating the upper levels is accommodated by a detachment fault at a stratigraphic level near the KU1 reflector. The central uplift at these deeper levels is divided into an intensely deformed core and a peripheral zone, the latter being dominated by radial thrust faults (KU0) and thrust-cored ridges (KU1). These radial thrust faults have a concave to the east geometry, with a bilateral axis of symmetry of around 82° (nearly east-west). Vergence on the thrust-cored folds is almost entirely to the west-southwest, showing net transport of material in that direction. Individual faults have a throw of up to 250 m and a total displacement of up to 500 m.

Subsurface deformation also extends to the area outside of the brim at shallow stratigraphic levels. Polygonal-style faults are present across the entire south and west of the seismic volume, with the dominant structures being southwest-dipping normal faults (Fig. 5). Tightly spaced NW-SE trending domino-type normal faults occur to the northwest of the crater with a consistent change of dip direction from southwest to northeast, and a zone of conjugate fault sets in the middle. The region to the east of the crater lacks any substantial deformation, except for 2-3 concentric faults extending up to 5 km beyond the brim, and several concave-up ‘negative flower structures’. These transtensional strike-slip faults are rooted in older normal faults in the Lower Cretaceous sequence.

3D seismic evidence for a hypervelocity impact origin

The 3D seismic data provide compelling evidence for a hypervelocity impact origin for the Nadir Crater. The combination of structural and stratigraphic features and velocity data described above allow us to understand the 3D anatomy of this structure in unprecedented detail. The crater depth to diameter ratio (1:40), central uplift diameter to crater diameter ratio (1:5), stratigraphic uplift to crater diameter ratio (1:22), and the structural characteristics of the stratigraphic uplift and annular moat are all consistent with observations from confirmed impact craters ^10,11. The geomorphic characteristics of the contemporaneous seabed beyond the crater, including the large resurge scar (Fig. 2), are also characteristic of marine craters ^9,12. The increase in seismic velocity and assumed loss of porosity beneath the crater floor is consistent with that observed for sedimentary target and marine target craters such as Mjølnir ¹³. The stratigraphy within the crater of a chaotic layer between KPg1 and 2 and a stratified low amplitude layer between KPg2 and 3 (Fig. 3) is consistent that observed at the Chicxulub impact structure ¹⁴. The improved seismic imaging below the crater (Fig. 2) also shows that there are no ‘bottom-up’ features such as salt diapirism or volcanic vents that would be consistent with alternative models of circular crater formation ^1,15,16.

These data thus provide exceptional support for an impact origin based on geophysical data alone. Most buried impact craters are first identified morphologically using geophysical data but are not viewed as being confirmed craters formed by hypervelocity impacts without rock samples showing products of high shock pressure unique to impacts ¹⁷. Many geophysical anomalies with circular planform morphologies are non-unique and can be formed by terrestrial processes, and there are multiple examples of such features being wrongly identified as impact structures ¹⁷. However, Nadir is the best global example where 3D imaging provides a complete set of near-diagnostic features which require an impact origin to explain. We consider that the features described above are unique to a hypervelocity impact process, particularly in the context of the Guinea Plateau, where other genetic processes can be definitively ruled out. Therefore, we propose that there can be extraordinary cases where clear imaging of these features using high-resolution seismic data could be viewed as sufficient to classify a structure as an impact crater, and that such high-confidence cases merit inclusion in crater databases ^18-20, particularly for buried craters that cannot be accessed by drilling. However, we suggest that the robust identification of such morphological characteristics is only likely to be possible for marine/sedimentary-target impact craters that are rapidly buried after formation, and where the impact stratigraphy and crater fill is sufficiently well preserved and imaged.

Reconstructing impact angle

Reconstructing impact angle is important to understand the hazard potential of hypervelocity impacts, including quantification of target material vaporized, air blast pressure, thermal radiation, ionospheric disturbance, and tsunami characteristics ^21-23. The Nadir Crater is nearly circular in plan view, with the central peak occurring very close to the center of the crater (Figs. 3). This is consistent with an impact angle greater than 15° above horizontal ¹⁰. However, subsurface deformation, particularly around the central uplift, is not uniform (Figs. 4, 5). The crater is distinctly asymmetric with steeper rim faults and a deeper ring syncline in the northeast in comparison to the southwest. This is consistent with results of oblique impact experiments ²⁴, impact simulations ²⁵, and observations of confirmed impact craters ²⁶, which show that a deeper annular moat would be expected in the uprange direction. However, inherited and reactivated normal (or transtensional faults) add complexity to the interpretation, as the inherited structural fabric has a strong NW-SE fault orientation.

We consider that the bilateral symmetry and concave-to-the-east morphology of the radial thrusts provide the best evidence for angle of impact, as the dominant target weakening/acoustic fluidization ²⁷ process in the central uplift means that this area is least susceptible to structural inheritance. Similar curved radial thrusts are observed in a number of other mid-sized impact craters, including Upheaval Dome ²⁸, Spider Crater ²⁹ , Matt Wilson Crater ³⁰. In these cases, the radial thrusts are characteristic of relatively low angle impacts, likely under 30°. As with these analogues, the curvature of the imbricated, radial thrusts and the consistent direction of vergence can be used to determine the angle of impact. For Nadir, the thrust faults and related folds are west-southwest verging, which we interpret as the downrange direction. Thus, the impactor that formed the crater likely came from the east-northeast, approximately parallel to the bilateral axis of symmetry of ~82°. The subsurface ‘sheltered zone’ to the east of the crater (Fig. 5) is consistent with this being the uprange side of a low angle impact, where shock-related stress would likely be lowest ³¹. This can be further tested by future full 3D numerical impact simulations of a marine impact, including more representative physical properties than previously modelled ¹.

Beyond the brim: regional subsurface damage zone

The damage zone in sedimentary-target marine craters is typically restricted to an area referred to as the ‘brim’, that forms because of concentric normal faulting of weak, stratified target material ^9,32,33. This deformation typically extends 1-2 crater diameters from the rim ³⁴, consistent with that which we observe for the Nadir Crater (~1:2.5). However, at Nadir the shallow target stratigraphy also displays extensive structural deformation beyond the brim to the south, west and north, despite the absence of tectonic deformation ⁶. This damage zone extends vertically from close to the KU1 horizon to the KPg1 horizon but does not extend into the overlying Paleogene sequence. This strain appears to have been accommodated by a detachment at or near the KU1 horizon. Scientific drill cores from the equivalent sequence on the conjugate South American margin offshore Suriname show that this sequence likely consists of black shales, with a high total organic carbon content ^6,35. Such sediments are known to act as detachment surfaces, or décollement, in tectonic deformation ³⁶.

The fault patterns beyond the brim show pronounced variations in structural style, particularly in the north and southwest of the plateau, with respect to the crater. We interpret the polygonal-type faults to have formed due to a combination of two processes. The first is volume loss due to dewatering and compaction, induced by rapid pore-pressure fluctuations and overpressure generation by seismic shaking during passage of the initial pressure wave. The second contributing factor is the lack of confining stress at the margin of the plateau. This may have resulted in lateral transfer of material to the southwest (Fig. 6B), and initiated collapse of material from the plateau margin ¹. This lateral transfer likely further exacerbates the tendency to generate submarine landslides in such settings, beyond the triggering mechanism represented by seismic shaking.

The target stratigraphy to the east of the brim doesn’t display any evidence of structural deformation, except for two distinct arrays of left-lateral strike-slip faults to the NE of the crater (Fig. 4). This lack of subsurface deformation may be in part due to the greater confining pressures in this area, at a greater distance from the plateau margin. However, we suggest that this area also experiences lower levels of transient stress from the impact itself because of the inferred impact trajectory. We propose therefore that strain beyond the crater primarily occurs downrange and lateral to the crater, with little deformation in the uprange direction in what we refer to as a “sheltered zone”. This is similar to the “forbidden zone” concept developed for ejecta distribution from low-angle impacts, where ejecta is not observed directly uprange ^24,31,37.

Multi-stage evolution of marine impact craters

Seismic observations and numerical modelling of the Nadir Crater ¹ suggest that the transient crater floor and surrounding seafloor was substantially modified in a short time period following the impact. We propose a multi-stage model of crater formation and modification for the Nadir Crater, which is likely to be applicable for marine impact craters generally.

Initial impact excavation resulted in the formation of the transient cavity (Fig. 6A, B). The shock wave, decaying to a seismic wave, would have passed through the brim and wider region during the excavation stage, leading to fracturing, large-scale overpressure generation and seismic shaking across the wider region, far beyond the crater brim (Fig. 6B). This likely occurred in the first few seconds (assuming a P-wave velocity of 1500-2000 m/s) after the impact, although dewatering and fault development likely continued later into the crater modification stage.

This was followed by the transient crater modification, which structural relationships indicate proceeded from inside to out. Formation of the central uplift occurred first, through rebound of the crater floor and inward flow of dynamically weakened/acoustically fluidized target material and faulting. Subsequently, but overlapping in time and starting on the uprange side, inward collapse of the transient crater rim formed the annular moat, or rim syncline, and terraces (Figs. 3, 4, 6C). Away from the central uplift, this stage involved substantial reactivation of pre-existing normal faults, or transtensional faults, especially in the uprange direction.

Crater modification then continued with the inward-lateral (centripetal) transfer of shallow, poorly consolidated target stratigraphy towards the center of the crater, forming the crater brim (Fig. 6D). The lateral transport of material was associated with both plastic and brittle deformation. Seismic observations show that the shallow stratigraphy is substantially extended in the crater brim area with thickening and reverse faults in the inner part of the annular moat, particularly on the north-east and southwest margins of the crater. Stratigraphic thickening in this sequence occurs due to the space problem resulting from convergent inward flow on a circular structure. Overturned folds are also present, not as part of the ejecta flap (e.g.,¹⁰) but within the proximal target stratigraphy, around the annular moat and central uplift periphery. These are proposed to form because of the poorly consolidated nature of the shallow target stratigraphy, rather than from dynamic rock weakening/acoustic fluidization. Strike-slip faults and extensional duplexes also suggest lateral transfer of target material towards the recently evacuated crater during this stage. We note that the reactivated normal faults (Figs. 4E and 6C) form nucleation points for subsequent imbricate thrusts to form underneath the crater rim, likely because of a large step, or displacement, of the detachment surface near the KU1 horizon in the uprange direction. This demonstrates that the normal faults below the crater rim formed prior to the thrust faults that formed as a result of inward flow of material from the crater brim.

The newly formed crater would initially have been around 230 m deep immediately at the end of the crater modification stage, with a prominent central uplift (Fig. 3 and Fig. S1). Although this is shallower than typical impact craters of this size ¹¹, this would have rapidly been infilled by an impact breccia, which are suggested to move in ground hugging flows during emplacement ^2,38,39. However, in a marine target crater there is a subsequent resurge stage, which results in a rapidly emplaced layer on top of this surface to produce a final, even shallower crater floor (KPg3). Evidence of resurge is recorded both as a scar to the east in the 3D volume and as a low-reflectivity layer infilling the crater. At Chicxulub the equivalent resurge deposit is a sorted suevite layer consisting of proximal ejecta and rip-up material that returned to the crater as a turbid resurge flow and then settled on the timescale of hours^2,40. These results show that marine craters are likely to have a suppressed morphology, particularly a crater depth to diameter ratio, reduced in this case from 1:40 to 1:130 ^1,41.

Marine impact hazards: tsunami-seabed interactions and liquefaction

Following the impact, most of the displaced water moved outward from the impact as a rim-wave tsunami, a product of proximal ejecta landing in the water and the outward movement of the transient cavity in the water layer (Fig.6B-D) ¹. The high energy of the subsequent resurge event is shown by the presence of the large resurge scar to the east of the crater (Fig. 3). This feature suggests that the returning resurge tsunami amplitude was sufficiently large to interact with the seabed at a distance of ~20 km from the crater rim, even at a likely water depth of ~800 m ¹. This is consistent with numerical models of tsunami heights (depth) for marine-target impacts ^1,22. Resurge gullies have been observed in other marine craters, such as Flynn Creek ⁹ and Lockne ⁴² but these are typically narrower and lack the large, arcuate morphology of this feature. Some of the sediment deposited during the resurge was subsequently transported back out of the crater, based on the presence of possible outwash deposits beyond the brim (Fig. 3).

The 3D seismic data also allow us to test the hypothesis that the extensive chaotic layer outside of the crater (Figs. 3, 4), immediately below the contemporaneous crater floor (KPg1) is linked to the impact event ¹. The concentric ridges that form outside of the crater rim are not directly related to underlying structures but appear to be formed within the chaotic unit itself, between the KU 4 and KPg 1 horizons. The distinctive seismic facies are like those observed in mass transport deposits (e.g. ⁴³), with the concentric ridges in this case inferring lateral (radial) transport of sediment away from the crater. We infer that this unit represents a seismite deposit: rapid dewatering induced by seismic shaking was followed by a phase of outward (with respect to the crater) shear at the seabed caused by the initial train of tsunami waves, leading to buckling and local ramp folding that produced concentric ridges. This facies extends far beyond the seismic survey outline, across much of the Guinea Terrace (see full extent in ¹), suggesting that the seismic effects and tsunami waves were sufficiently large to deform and rework the seabed across an area of ~10⁵-10⁶ km². This may be an important feature for other marine craters and illustrates that shallow hazards associated with liquefaction of water-saturated and uncompacted sediments are a more important factor for subsea infrastructure than has previously been realized.

A natural laboratory for marine impact research

The 3D seismic data across the Nadir Crater provides an unprecedented opportunity to test the impact crater hypothesis, develop new models of crater formation in an oblique marine impact and to understand the environmental consequences of such an event. High-precision dating of the crater, and final confirmation of an impact origin, requires the recovery of cores by ocean drilling. Nadir provides an ideal natural laboratory for further testing and refining marine impact crater models through further seismic analysis, numerical modelling and ocean drilling.

The MC3D survey in Republic of Guinea was acquired in 2019 by PGS in water depths of 60-4500 m. Acquisition parameters include 12 streamers of 8.025 km length and a separation distance of 150 m. The shot interval was 16.7 m, with a sample rate of 2 ms. Bin dimensions are 6.25 m x 25 m for acquisition and 12.5 m x 12.5 m for processing, with a fold of 80. The record length for the survey is 10,000 ms. Data were processed using a proprietary Pre- Stack Depth Migration (PSDM) sequence (Table S1, Supplementary Materials). Seismic velocities have been tomographically derived to improve imaging around the crater, where velocities vary substantially compared to the regional trends. Seismic interpretation was carried out using Schlumberger Petrel 2020 software, including horizon mapping, structural element mapping, velocity analysis and attribute analysis. Stratigraphic ages were correlated using seismic data from the GU-2B-1 and Sabu-1 wells in the east of the Guinea Plateau. Ages in these wells were derived from industry reports documenting the microfossil assemblages, on cuttings samples (sample interval ~10 m) ⁶.

Acknowledgments:

We are grateful to PGS and Société Nationale de Petroles (SONAP) in the Republic of Guinea for access to 3D seismic data for this study. We also thank Schlumberger for the provision of an academic license of Petrel 2020 for seismic interpretation. We extend thanks to other academic collaborators involved in IODP proposal 1004 and the Sed Strat Seis research group at Heriot-Watt University for discussions about the impact crater hypothesis and its wider implications.

Funding: UN, DD and SG acknowledge NERC grant number NE/W009927/1. This is University of Texas Institute for Geophysics Contribution #3967 and Center for Planetary Systems Habitability Contribution #0072. GSC acknowledges support from STFC grant ST/S000615/1.

Author contributions: UN was responsible for conceptualization of the key research idea, led the research grant for funding specific to this project, was the main interpreter of the data, wrote the original draft and carried out subsequent editing. WP also conceptualized the idea and interpreted the data and contributed to reviewing and editing the manuscript. SG contributed to funding acquisition, data interpretation and reviewing and editing the manuscript. TK, VB, DD and GC all contributed to the data interpretation and reviewing and editing of the manuscript.

Competing interests: The authors declare that they have no competing interests.

Data and materials availability: All data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Materials. Original seismic segy data and well data were provided by PGS and the Republic of Guinea under a confidentiality agreement and remain the property of these organizations. Enquiries about data access should be directed to PGS (https://www.pgs.com/company/about-us/contact-us/europe-africa-and-the-middle-east/).

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published 03 Oct, 2024

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3D anatomy of the Cretaceous-Paleogene age Nadir Crater

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Introduction

Geological setting of the Nadir Crater

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