Petroleum Prospects Research Articles

Перспективы нефтегазоносности и характеристика продуктивных горизонтов кембрийских межсолевых отложений центральной части Лено-Тунгусской нефтегазоносной провинции

Перспективы нефтегазоносности и характеристика продуктивных горизонтов кембрийских межсолевых отложений центральной части Лено-Тунгусской нефтегазоносной провинции

Rock properties and in-situ stress state of the Egilabria Prospect, Lawn Hill Platform, Queensland

The Energy component of Geoscience Australia’s Exploring for the Future (EFTF) program is aimed at improving our understanding of the petroleum resource potential of northern Australia, in partnership with the state and territory geological surveys. The sediments of the Mesoproterozoic South Nicholson Basin and the underlying Paleoproterozoic Isa Superbasin in the Northern Territory and Queensland are amongst the primary targets of the EFTF Energy program, as they are known to contain organic-rich sedimentary units with the potential to host unconventional gas plays, although their subsurface extent under the cover of the Georgina Basin is presently unknown. In order to economically produce from unconventional reservoirs, the petrophysical rock properties and in-situ stresses must be conducive to the creation of secondary permeability networks that connect a wellbore to as large a reservoir volume as possible. This study utilises data from the recently drilled Armour Energy wells Egilabria 2, Egilabria 2-DW1, and Egilabria 4 to constrain rock properties and in-situ stresses for the Isa Superbasin sequence where intersected on the Lawn Hill Platform of north-west Queensland. These results have implications for petroleum prospectivity in an area with proven gas potential, which are discussed here in the context of the rock properties and in-situ stresses desired for a viable shale gas play. In addition, these results are relevant to potential future exploration across the broader Isa Superbasin sequence.

Investigating the effect of burial histories on the clumped isotope thermometer: An example from the Green River and Washakie Basins, Wyoming

Abstract The Δ47 clumped isotope thermometer has been applied to multiple studies aimed at reconstructing the paleoelevation and paleoclimate of sedimentary basins and paleosol sequences. Ideally, this technique directly preserves the temperature of carbonate formation, avoiding any speculation on the composition of surface water from which the carbonate precipitated. Recently, however, concerns about post-depositional alteration of the Δ47 isotope signature from the effects of burial and/or diagenetic alteration have arisen, potentially complicating the application of the Δ47 clumped isotope thermometer for determining paleo-surface temperatures. Here we investigate the effect of burial history on mass-47 clumped isotope. To this purpose we collected samples, from the surface and from drill cores, in two different areas of the Greater Green River basin: the Washakie Basin near Rock Springs, Wyoming and the Green River Basin near Pinedale, Wyoming. Both basins are filled with a thick sequence of Eocene lacustrine strata and the thermal histories of both basins are well documented from petroleum prospecting studies. Clumped isotope Δ47 compositions were measured from lacustrine micritic limestones with a range of peak burial depths from 1 to 6.5 km. For samples from the Washakie Basin that did not experience burial depths exceeding ∼2000 meters, the measured Δ47 values vary from 0.623‰ to 0.684‰, yielding carbonate formation temperatures consistent with previously hypothesized Paleocene-Eocene surface temperatures. In contrast, samples from the Green River Basin, collected from greater burial depths, demonstrate significantly lower Δ47 values (higher temperatures). The consistency of δ18O values and lack of CL evidence for recrystallization suggest closed-system resetting of the clumped isotope thermometer by either partial solid-state re-ordering or carbonate reprecipitation during burial. The Δ47 values of the deeply buried samples have been compared to values derived from recrystallization and temperature history reordering models (THRMs). Both recrystallization and reordering models are successful at predicting Δ47 reordering at burial temperatures >100 °C. These observations, from samples collected from a basin with a remarkably well-constrained thermal history and geothermal gradient, highlight the challenges in elucidating burial histories or diagenetic processes solely from clumped isotopic compositions.

New Regional Data and Advances in Understanding of the Stratigraphy, Tectonics, Structure and Prospectivity of the Gulf of Papua (Papua New Guinea)

Between 2015 and 2017, Searcher Seismic acquired 32,478 km of long offset PSDM 2D seismic data and reprocessed an additional 12,972 km of previously acquired 2D data in the Gulf of Papua, Papua New Guinea (PNG). The new data has resulted in a significant improvement in subsurface imaging and areal coverage, providing the foundation for a new integrated analysis of the region. In addition, a regional drop core geochemistry and heat flow survey provides important clues regarding the existence of working petroleum systems in the Gulf of Papua. The evaluation of these new datasets has improved the current understanding of the stratigraphy, plate tectonics, local structure petroleum prospectivity of the Gulf of Papua.New seismic allowed identification of several depositional packages that are often bounded by regional unconformities related to the tectonic development of the area. Seismic and shipborne gravity/magnetics analyses allowed a confident identification of the following events/packages: Moho event allowing estimation of the crustal thickness and differentiation between oceanic and crust and calibration of the heat flow measurements;Paleozoic severely folded succession analogous to eastern Australia accretionary terrains;Permian analogous to the Bowen Basin in Queensland, Australia;Triassic to Jurassic succession supported by the existence of the Jurassic seep identified by the Davaria geochemical survey;Presence of previously unidentified block faulted highs with Miocene reefs and carbonate platform build-ups;Pliocene and younger basin sandstone floor fans; andExtension of the compressional front into deep water Gulf of Papua.These observations have been integrated into an updated plate tectonic model that predicts widespread deposition of the Permian and Triassic to Tertiary source rocks estimated to be often within the hydrocarbon generative window.

FEATURES OF THE GEOLOGICAL STRUCTURE OF SEDIMENTARY COVER OF FROLOVSKAYA MEGADEPRESSION DERIVED FROM THE RESULTSOF GENERALIZATION OF GEOLOGICAL AND GEOPHYSICAL DATA

The article is devoted to the features of the geological structure of Jurassic-Cretaceous deposits of Frolovskaya megadepression. These features are derived from the results of the generalization of the materials of regional seismic profiles, maps of gravity and magnetic prospecting, drilling data. The main petroleum prospects are associated with Jurassic deposits and pre-Jurassic basement. We conclude that it is necessary to intensify further researches with carrying out the entire complex of geophysical methods, including magnetic and gravity prospecting with an increased density of observations.

A diverted submarine channel of Early Cretaceous age revealed by high-resolution seismic data, SW Barents Sea

Abstract Mud-rich prograding sediment lobes make for most of the Barremian – Albian stratigraphic record in the SW Barents Sea. Submarine canyons and channels potentially represent key components of sediment transport from shelf to basin floor but geological evidences are lacking. We present high-resolution seismic data and scrutinize an elongated, ∼150-km long bright seismic amplitude and resistive anomaly located alongslope of a NW-sourced Barremian delta in the SW Barents Sea. Seismic interpretation is performed on a comprehensive database comprising 3D/2D high-resolution P-Cable and conventional seismic data, tied to three exploration wells to provide age-control on key horizons. Our results highlight that the elongated geophysical anomaly originates from a soft layer deposited over a harder, erosional surface. The erosive morphology displays three narrow, V-shaped incisions to the NE of the Hoop area which develop into a single, ∼6 km-wide, U-shaped channel towards the transition to the Fingerdjupet Subbasin. The geological feature is named Ceres and interpreted as a submarine channel carved in Aptian, a period of marked sea level rise and sediment starvation in the Hoop area. An evolutionary model of a diverted submarine channel is proposed where a flooded delta lobe acted as a topographic barrier, funneling bottom currents and thereby carving an alongslope, possibly contouritic channel. This is the first documented case of a submarine channel pathway – delta lobe interaction on the Norwegian continental shelf. To account for the geophysical expression of Ceres, two competing explanations are discussed: (1) hydrocarbon-bearing sands, and (2) organic-rich source rock. Both scenarios have important implications for petroleum prospectivity: a faulted stratigraphic trap holding large volumes of hydrocarbons or alternatively the channel-controlled distribution of mature Aptian source rock in the SW Barents Sea.

Gravity-flow deposits and their exploration prospects in the Oligocene Dongying Formation, northwestern Bozhong Subbasin, Bohai Bay Basin, China

Abstract Gravity-flow deposits are important hydrocarbon exploration targets in most basins. In this study, an integration of geological, geophysical, and geochemical analysis is used to investigate the gravity-flow deposits and their petroleum prospects in the Oligocene Dongying Formation (E3d), Bozhong Subbasin, Bohai Bay Basin. Mass-transport deposits (MTDs) and channel-lobe complexes are the main gravity-flow depositional units. The mass-transport deposits (MTDs) show hummocky and chaotic reflections with poor continuity and variable amplitude. The channels display linear geomorphology with weak root-mean-square (RMS) amplitude, and the lobes are dominated by high-continuous and high-amplitude reflection at the terminal channels. The formation of gravity-flow deposits is primarily controlled by high sedimentation rate during a relative lowstand of lake level. The E3d3 source rock has TOC contents in the range of 0.6–3.1%, Rock-Eval S2 values in the range of 0.7–19.8 mg HC/g rock, and Hydrogen indices (HI) in the range of 100–600 mg/g TOC. The E3d2L source rock has TOC contents ranging from 0.5 to 1.9%, Rock-Eval S2 values from 0.4 to 7.8 mg HC/g rock, and HI from 40 to 480 mg/g TOC. Both E3d3 and E3d2L source rocks have good hydrocarbon-generation potential. The E3d3 and E3d2L source rocks have entered the oil-generation peak window with the vitrinite reflectance (Ro) higher than 1.0%. Oils generated from the underlying source rocks shortly migrated to the overlying gravity-flow lithologic traps. The gravity-flow reservoirs could serve as potential and effective hydrocarbon exploration targets.

Thermal history of a Triassic sedimentary sequence verified by a multi‐method approach: Edgeøya, Svalbard, Norway

AbstractTemperature impacts the quality of reservoir and source rocks, thereby representing an important aspect of petroleum prospect assessments of any basin. This case study of the Triassic basin of Edgeøya, eastern Svalbard, reevaluate earlier burial estimates that were solely based on organic matter maturation data from organic rich shales. Here, we estimate temperatures using a multi‐method approach: Rock‐Eval pyrolysis parameters, fluid inclusions in diagenetic quartz, and inorganic diagenesis signatures of sandstones. Data were collected from organic rich shales of the Botneheia and Tschermakfjellet formations and coal bearing sandstones of the De Geerdalen Formation. Rock‐Eval pyrolysis data indicate that Botneheia and Tschermakfjellet formations experienced burial temperatures of about 124–138°C while the De Geerdalen Formation experienced temperatures ≥92°C. Homogenization temperatures of the De Geerdalen Formation sandstones give similar diagenetic temperatures, from 70 to 124°C, while the kaolinite to dickite transformation implies the temperatures >90°C. Furthermore, the absence of illite formation associated with kaolinite suggest that temperature have never exceed 130°C. Integrating various methods validate spatial variations in temperature proxies and constrain the thermal history of this basin. Cretaceous intrusions have locally affected the temperatures and have obscured regional subsidence and uplift trends. The effect of igneous intrusions on inorganic matter is very limited, but intensive on organic matter. These differences between organic and inorganic thermal indices help in distinguishing of magmatic from burial heating. This study has therefore relevance in deciphering the thermal history of sandstones experiencing magmatic activity coupled with multiple burial and uplift events.

Morphometric analysis of sediment conduits on a bathymetric high: Implications for palaeoenvironment and hydrocarbon prospectivity

AbstractCanyons and other sediment conduits are important components of the deep‐water environment and are the main pathways for sediment transport from the shelf to the basin floor. Using 3‐D and 2‐D seismic reflection data, seismic facies and statistical morphometric analyses, this study showed the architectural evolution of five canyons, two slide scars and four gullies on the southern part of the Loppa High, Barents Sea. Morphometric parameters such as thalweg depth (lowest point on a conduit's base), wall depth (middle point), height, width and base width, sinuosity, thalweg gradient, aspect ratio (width/height) and cross‐sectional area of the conduits were measured at intervals of 250‐m perpendicular to the conduits’ pathways. Our results show that the canyons and slide scars in the study area widen down slope, whereas the gullies are narrow and short with uniform widths. The sediment conduits in the study area evolved in three stages. The first stage is correlated with a time when erosion and bypass were dominant in the conduits, and sediment transferred to the basin in the south. The second stage occurred when basin subsidence was prevalent, and a widespread fine‐grained sequence was deposited as a drape blanketing the canyons and other conduits. A final stage occurred when uplift and glacial erosion configured the entire southern Loppa High into an area of denudation. Our work demonstrates that the morphometric parameters of the canyons, slide scars and gullies generally have increasing linear trends with down‐slope distance, irrespective of their geometries. The morphometric analysis of the sediment conduits in the study area has wider applications for understanding depositional processes, reservoir distribution and petroleum prospectivity in frontier basins.

A simple relationship between thermal conductivity and seismic interval velocity

The subsurface temperature is of major interest for assessment of the petroleum prospectivity of a sedimentary basin. A key parameter in modeling the thermal structure of the subsurface is thermal conductivity. The information about lateral variation of this parameter is usually sparse. We propose a simple linear relationship between thermal conductivity and seismic velocity for clastic sedimentary rocks. The coefficient of proportionality depends on the clay fraction. This implies that thermal conductivity and seismic velocity have a similar sensitivity to porosity. Both thermal conductivity and seismic velocity increase with decreasing porosity. For a given porosity, quartz-rich rocks have higher thermal conductivity than clay-rich rocks, which is in agreement with experimental observations. Whenever seismic velocity models are available from seismic surveying, the proposed thermal conductivity-velocity relationship can be used to obtain laterally varying 2D and 3D thermal conductivity models for use in basin modeling.

The pre-breakup stratigraphy and petroleum system of the Southern Jan Mayen Ridge revealed by seafloor sampling

The Jan Mayen Microplate Complex (JMMC) in the NE Atlantic is interpreted to mostly consist of continental fragments with possible interstitial embryonic oceanic crust. A complex Cenozoic rifting history accompanied by extensive extrusive and intrusive volcanism have made the geological characterization of the JMMC challenging especially due to poor seismic imaging beneath the breakup basalt succession. The presence of continental crust in the JMMC is inferred by seismic and magnetic data, but ground truthing evidence have yet to be provided. Here, we present the results from a seafloor sampling campaign undertaken in 2011 on the Southern Jan Mayen Ridge complex. Seabed samples were recovered using a gravity corer and a dredge along a 1000 m high escarpment with a 19° slope. Sampling locations were selected based on the interpretation of seismic profiles that suggest the presence of possible pre-breakup successions outcropping along this steep escarpment. Results include a sequence of samples with age diagnostic palynomorph assemblages ranging from Permian/Triassic to Eocene, and including igneous samples related to the Early Eocene breakup volcanism. Importantly, the samples were retrieved from hard substrate in an erosional gully lacking overburden sediments and have ages arranged in younging upward sequential order, supporting their near in-situ position. The sampling results were integrated into a lithostratigraphic pseudo-well that can be used to constrain the evolution and breakup of the JMMC. Additionally, evidence for active migration of Jurassic sourced hydrocarbons comprise the first indication of a working hydrocarbon system, with important implications for the petroleum prospectivity of the Dreki area. Finally, these results confirm that the Southern Jan Mayen Ridge is indeed a sliver of continental crust.

Petroleum system modeling of the East Coast Basin, Hawke Bay, New Zealand

This study evaluates the petroleum prospectivity of the East Coast Basin, an element of the Hikurangi convergent margin of New Zealand. The basin tectonic environment changed from a dormant convergent margin to convergent margin around the early Miocene, likely causing a decrease in the basin thermal regime. Two end-member paleoheat flow scenarios were used to evaluate thermal maturation of two key source rocks, the Waipawa Black Shale and Whangai Formation, based on calibration to six wells across the basin using vitrinite–inertinite reflectance and fluorescence analysis, as well as Rock-Eval Tmax (the temperature at which the maximum rate of hydrocarbon generation occurs during pyrolysis analysis), thermal alteration index, apatite fission track analysis, and present-day temperatures. This study finds that paleobasal heat flow ranged between 40 and 55 mW/m−2 and decreased to 30 mW/m−2 between 15 and 5 Ma, as bracketed by the two end-member heat flow scenarios. The heat flow scenarios were applied to a palinspastically reconstructed basin and petroleum system model across Hawke Bay. We find that the two distinct heat flow scenarios cause a 3–6.5 m.y. difference in the relative timing of hydrocarbon generation across the basin. Structural events in the basin associated with convergent margin tectonics act as the main control on the timing of generation. Modeling results show transformation of kerogen to hydrocarbons began between early and late Miocene for both source rocks depending on the structural regime in the basin. The structural control on source rock maturation highlights the need for robust palinspastic reconstructions in addition to paleothermometric data to evaluate the petroleum prospectivity of convergent margin basins.

Формирование нефтегазоносности Вуктыльского надвига по данным 1D бассейнового моделирования

This article discusses the modeling of oil and gas generation processes at the Vuktyl Overthrust with usage of well Vuktylskaya-58 parametric data. These well cuts contain both the allochthon and autochthon parts of the overthrust. Despite the fact that gas and gas-condensate deposits within the basin were discovered in 60th of XX century, the deep sediments in this area remains poorly understood due to the difficult accessibility. The petroleum prospects of the area have not been clear. The PetroMod software 1D module was used for basin cross-section modeling. The result proved that the source rocks of the allochthon could generate only oil. In the deep sediments of the autochthon, the processes of generation of gases and condensates could form deposits not only in the deeper horizons, but also may have been involved in the formation of the major deposits of the Vuktyl gas condensate field. Generation and accumulation of hydrocarbons occurred mainly after overthrust dislocations, when the main traps formed in the deep-lying strata.

Shear margin moraine, mass transport deposits and soft beds revealed by high-resolution P-Cable three-dimensional seismic data in the Hoop area, Barents Sea

Abstract High-resolution seismic data are powerful tools that can help the offshore industries to better understand the nature of the shallow subsurface and plan the development of vulnerable infrastructure. Submarine mass movements and shallow gas are among the most significant geohazards in petroleum prospecting areas. A variety of high-resolution geophysical datasets collected in the Barents Sea have significantly improved our knowledge of the shallow subsurface in recent decades. Here we use a c. 200 km 2 high-resolution P-Cable 3D seismic cube from the Hoop area, SW Barents Sea, to study a 20–65 m thick glacial package between the seabed and the Upper Regional Unconformity (URU) horizons. Intra-glacial reflections, not visible in conventional seismic reflection data, are well imaged. These reflections have been mapped in detail to better understand the glacial deposits and to assess their impact on seabed installations. A shear margin moraine, mass transport deposits and thin soft beds are examples of distinct units only resolvable in the P-Cable 3D seismic data. The top of the shear margin moraine is characterized by a positive amplitude reflection incised by glacial ploughmarks. Sedimentary slide wedges and shear bands are characteristic sedimentary features of the moraine. A soft reflection locally draping the URU is interpreted as a coarser grained turbidite bed related to slope failure along the moraine. The bed is possibly filled with gas. Alternatively, this negative amplitude reflection represents a thin, soft bed above the URU. This study shows that P-Cable 3D data can be used successfully to identify and map the external and internal structures of ice stream shear margin moraines and that this knowledge is useful for site-survey investigations.

Unraveling Petroleum Degradation, Maturity, and Mixing and Addressing Impact on Petroleum Prospectivity: Insights from Frontier Exploration Regions in New Zealand

Determining oil quality is essential to identifying valuable resource accumulations. However, in new areas of exploration, little information is available on the processes affecting resource quality. Geochemical analyses of oil seeps from frontier regions of New Zealand’s East Coast illustrate an application of underutilized resource quality assessment techniques. Distributions of n-alkanes and isoprenoids reveal biodegradation, and thus potentially lower oil quality in the “southern” versus the “northern” oil seeps. However, sterane and terpane compounds are unaltered, indicating overall biodegradation of these oils is low to moderate. Additionally, lack of 25-norhopane indicates degradation of southern oils may be solely aerobic. Therefore, any subsurface accumulations are potentially unaffected. Investigation of sterane and hopane isomerization ratios and additional sterane and terpane maturity parameters is paired with diamondoid analyses of oil-to-gas conversion and petroleum mixing. Three distinct p...

Нефтегазоперспективные объекты палеозоя Западной Сибири, сейсмогеологические модели эталонных месторождений

Нефтегазоперспективные объекты палеозоя Западной Сибири, сейсмогеологические модели эталонных месторождений

Australian onshore petroleum acreage and releases 2018

This paper is a compilation of information provided by state and territory jurisdictions about onshore acreage and its availability for petroleum exploration in 2018. Australian state and territory governments continue to research and promote petroleum prospectivity to stimulate local and international investment in petroleum exploration by generating new exploration concepts and opportunities, facilitating discoveries and fostering new ideas to assist the nation’s upstream petroleum sector to keep on delivering the maximum net benefits to all Australians. Present and future policy directions that relate to onshore petroleum exploration are described, particularly for jurisdictions that are not making petroleum acreage available this year.

Carbazoles and benzocarbazoles confirm migration of leaked petroleum through caprocks and overlaying formations of Valhall Well 2/8-8 in the North Sea

A wildcat may not result in a petroleum prospect; however, it may indicate potential need for frontier exploration, since petroleum could leak into economic accumulations. Carbazoles and benzocarbazoles are nitrogen compounds in petroleum and can be employed to explicitly explain migration direction and distance of leaking petroleum. The hypothesis of this study is that the mechanism of the reaction involving the attraction of carbazoles to clay minerals on the matrix of the walls along their migration pathways determines the isomer that is preferentially attached to the mineral matrix. The objectives of this study are (a) to produce a profile for carbazoles and benzocarbazoles ratios in the cap rock overlying the reservoir, (b) to compare carbazole and benzocarbazole ratios to 20S/(20S + 20R) αααC29 Sterane maturity ratios (c) to infer migration direction from the carbazoles and benzocarbazoles ratio. Samples used were side wall cores and drill cuttings of water-based mud drilling. The EOM (extractable organic matter) from various formations overlying the reservoir was obtained using Soxtherm Automatic Equipment. The TPH (total petroleum hydrocarbon) was obtained from the EOM by using a precleaned isolute C18 500 mg / 3 mL column, eluted with hexane, while the polars were eluted with dichloromethane. Fractionation into saturates and aromatics was done using a silver nitrate–silica gel column. The profiles of 1,8/1,3 and 1,8/2,4 dimethyl carbazoles and the benzocarbazoles ratios show a vertical gradient of decreasing ratio with increasing vertical distance from the reservoir. This corroborates the %VRo equivalent of 20S/(20S + 20R) αααC29 Sterane and the carbazole ratios infer vertical migration of leaked petroleum.

Mafic intrusions, hydrothermal venting, and the basalt-sediment transition: Linking onshore and offshore examples from the North Atlantic igneous province

The emplacement of large intrusive complexes into sedimentary basins can have profound effects on host sedimentary rocks including deformation, thermal aureole metamorphic reactions, alteration of fluid-flow pathways, and the formation of associated hydrothermal vent complexes (HVCs). These processes can in turn have major implications for petroleum systems on the local and regional scale, and can contribute to global climate change due to the production and outgassing of greenhouse gases, such as [Formula: see text] and [Formula: see text]. Imaging these features and assessing their implications from seismic data beneath extrusive volcanic cover is challenging due to heterogeneities in the volcanic pile and at the basalt-sediment transition. We have evaluated combined field and laboratory petrophysical data from the Isle of Skye, Scotland, where we identify a seismic-scale example of extensive intrusions interacting with the base-basalt transition. We have also evaluated a unique onshore example of a linked sill and associated HVC cutting up through the lava sequence. We compare these field results with HVCs from reflection seismic data across the Vøring Marginal High, offshore Norway, where subbasalt saucer-shaped intrusions are also seen associated with HVCs cutting the lava sequence. Seismic imaging problems associated with the velocity heterogeneity of volcanic sequences, along with a historical lack of high-quality 3D data in volcanic regions worldwide, is suggested as having largely precluded the identification of these features in the past. The under-representation of these hydrothermal vents in the literature has key implications for the future appraisal of intrusion-related outgassing effects on the global climate such as those related to the Palaeocene Eocene Thermal Maximum, along with subbasalt petroleum prospectivity where they may alter maturation and migration pathways.

Upper Paleocene ultramafic igneous rocks offshore mid-Norway: Reinterpretation of the Vestbrona Formation as a sill complex

Continental breakup between northwest Europe and Greenland (approximately 56 Ma) was associated with widespread magmatism. Silica undersaturated alkaline porphyritic igneous rocks of a similar age have previously been dredged near the mid-Norwegian coast. These igneous rocks of the Vestbrona Formation have previously been interpreted as either igneous plugs or volcanic flows. New 3D seismic data indicate that relatively small sill complexes are abundant in the same region. In total, 36 sills with a size of [Formula: see text] have been mapped. In addition, 10 seismic horizons were interpreted and tied to nearby wells to obtain a robust stratigraphic framework. The sills mainly intrude Cretaceous and Paleocene sequences; however, one sill is also identified in the pre-Cretaceous sequences. The sills locally form erosional remnants on the seabed due to massive uplifting and erosion of the continental margin. Vintage igneous and sedimentary dredge samples have been reanalyzed, including petrography, geochemistry (X-ray fluorescence [XRF], X-ray diffraction [XRD]), biostratigraphy, and Ar-Ar geochronology. The new Ar-Ar data suggest that the sills are 1–2 Ma older than breakup (approximately 57–58 Ma). Furthermore, the biostratigraphy and petrography of two sediment samples suggest that the samples were collected from near in situ subcrops and not of an ice rafted origin. The sediment samples are of Danian age and are strongly metamorphosed, most likely by contact metamorphism resulting from heating during sill emplacement. The newly identified sills have implications for the petroleum prospectivity of the study area including source rock maturation within thermal aureoles and the long-term alteration of fluid migration pathways.