The syn-rift sedimentary cover of the North Biscay Margin (bay of Biscay): from new reflection seismic data

Abstract The Armorican Basin is a deep sedimentary basin lying at the footside of the North Bay of Biscay. From previous scattered inadequate data, the age and nature of this basin, oceanic domain or deep part of the Armorican margin itself were largely speculated. From this new seismo-stratigraphic study based on a dense seismic cover, the sedimentation within the Armorican Basin is beginning in the Aptian times, during the last tectonic rifting episode of the margin. The first sediments formation identified as the « 3B layer » is characterised on the profiles by a chaotic and transparent seismic facies and was emplaced by slumping process when the margin collapsed, at the final rifting phase, just before the oceanic accretion. The new seismic reflection data give also some informations on the polyphased evolution of the North Biscay Margin during the rifting period. Two main events occurred during the Lower Cretaceous times (the first one is pre-Berriasian, the second is Aptian), separated by a quiet tectonic period including the Upper Berriasian and Lower Aptian times. The first event is responsible of the margin tectonic structuration in some blocks, the second of collapsing and the emplacement of the allochthonous sediments (3B layer) in the Armorican Basin.

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Rift processes in the Westralian Superbasin, North West Shelf, Australia: insights from 2D deep reflection seismic interpretation and potential fields modelling

The APPEA Journal ◽

10.1071/aj14035 ◽

2015 ◽

Vol 55 (2) ◽

pp. 400 ◽

Cited By ~ 2

Author(s):

Catherine Belgarde ◽

Gianreto Manatschal ◽

Nick Kusznir ◽

Sonia Scarselli ◽

Michal Ruder

Keyword(s):

Seismic Reflection ◽

Potential Fields ◽

Moho Depth ◽

Late Permian ◽

Forward Modelling ◽

Seismic Reflection Data ◽

North West ◽

Reflection Seismic ◽

The North ◽

Reflection Data

Acquisition of long-offset (8–10 km), long-record length (12–18 sec), 2D reflection seismic and ship-borne potential fields data (WestraliaSpan by Ion/GXT and New Dawn by PGS) on the North West Shelf of Australia provide the opportunity to study rift processes in the context of modern models for rifted margins (Manatschal, 2004). Basement and Moho surfaces were interpreted on seismic reflection data. Refraction models from Geoscience Australia constrain Moho depth and initial densities for gravity modelling through standard velocity-density transformation. 2D joint inversion of seismic reflection and gravity data for Moho depth and basement density constrain depth to basement on seismic. 2D gravity and magnetic intensity forward modelling of key seismic lines constrain basement thickness, type and density. Late Permian and Jurassic-Early Cretaceous rift zones were mapped on seismic reflection data and constrained further by inversion and forward modelling of potential fields data. The Westralian Superbasin formed as a marginal basin in Eastern Gondwana during the Late Permian rifting of the Sibumasu terrane. Crustal necking was localised along mechanically-weak Proterozoic suture belts or Early Paleozoic sedimentary basins (such as Paterson and Canning). Mechanically-strong cratons (such as Pilbara and Kimberley) remained intact, resulting in necking and hyper-extension at their edges. Late Permian hyper-extended areas (such as Exmouth Plateau) behaved as mechanically-strong blocks during the Jurassic to Early Cretaceous continental break-up. Late Permian necking zones were reactivated as failed-rift basins and localised the deposition of the Jurassic oil-prone source rocks that have generated much of the oil discovered on the North West Shelf.

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A NORTH WEST SHELF TRIASSIC REEF PLAY: RESULTS FROM ODP LEG 122

The APPEA Journal ◽

10.1071/aj88028 ◽

1989 ◽

Vol 29 (1) ◽

pp. 328 ◽

Cited By ~ 1

Author(s):

P.E. Williamson ◽

N.F. Exon ◽

B. ul Haq ◽

U. von Rad

Keyword(s):

Seismic Reflection ◽

Upper Triassic ◽

Seismic Facies ◽

Late Triassic ◽

Seismic Reflection Data ◽

Reef Complex ◽

North West ◽

Exmouth Plateau ◽

The North ◽

Reflection Data

Site 764 of the Ocean Drilling Program (ODP), drilled during Leg 122 in the Exmouth Plateau region, cored 200 m of Upper Triassic (Rhaetian) reef complex. This site, on the northern Wombat Plateau (northernmost Exmouth Plateau) represents the first discovery of Triassic reefal material near the Australian North West Shelf. Seismic reflection data through Site 764 show that the reef itself corresponds predominantly to a seismically poorly reflective zone. A number of regional unconformities appear to correspond, however, to traceable seismic horizons which pass with reduced amplitude through the reef, indicating stages of reef growth separated by erosion or non- deposition. Seismic facies around the edges of the reef are consistent with the deposition of wedges of prograding reef- derived detritus.Application of the seismic criteria for reef recognition established at ODP Site 764, to other seismic reflection data on the Wombat Plateau, demonstrates that a major Upper Triassic reef complex fringes the margins of the Wombat Plateau. The Wombat Plateau lies at the western end of the North West Shelf, which was part of the southern margin of a warm Tethys Ocean in the Late Triassic, at a palaeolatitude of 25- 30°S. Upper Triassic reefs are known from southeast Indonesia and Papua New Guinea, and now the Wombat Plateau, and may be common elsewhere along the outer margin of the North West Shelf. Upper Triassic reef complexes, with their associated reservoir, source and seal facies, could represent an exciting new petroleum exploration play for the entire North West Shelf. Facies analysis suggests that they are likely only on the outer shelf and slope. Shallow Triassic reef complexes are clearly identifiable using high resolution seismic reflection data. Seismic reflection data of lower resolution may well reveal the associated detrital carbonate wedges, which are more laterally extensive than the reefal core, deeper in the section.

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Gravity tectonics in the SE Basin (Provence, France) imaged from seismic reflection data

BSGF - Earth Sciences Bulletin ◽

10.2113/gssgfbull.181.6.503 ◽

2010 ◽

Vol 181 (6) ◽

pp. 503-530 ◽

Cited By ~ 14

Author(s):

Claude Rangin ◽

Xavier Le Pichon ◽

Youri Hamon ◽

Nicolas Loget ◽

Agnès Crespy

Keyword(s):

Seismic Data ◽

Sedimentary Cover ◽

Field Work ◽

Seismic Reflection Data ◽

Reflection Data ◽

Structural Framework ◽

Geological Maps ◽

Fold And Thrust Belt ◽

Thrust Zone ◽

The Alps

AbstractUsing industrial seismic data available in the French Southeast Basin in Provence, we put into evidence thin skinned processes that have dominated tectonics in this basin since the Oligocene. These interpretations are then replaced within the regional structural framework of SW France with geological maps and field work. A thick Mesozoic and Cenozoic sedimentary cover is detached on a main décollement frequently localized within the Triassic evaporites. The underlying basement is undeformed. The Mid-Durance fault, the Luberon, Trévaresse, and the Ventoux-Lure thrust zones and the Diois-Baronnies fold and thrust belt are produced by thin-skinned tectonics, the associated structures having no roots within the pre-Triassic basement. This thin-skinned deformation is interpreted as resulting from a regional southward gravity mass flow, induced by the westward Alps extrusion, followed in recent times by radial collapse of the Alps. The incipient stage of this gravity sliding occurred during the Late Oligocene in the Diois-Baronnies (the former Mesozoic Vocontian basin), and then rapidly progressed to the south across the Ventoux-Lure thrust zone in Provence during the Miocene. Southward, this gravity sliding vanishes approaching the E-W trending structural high of the Eocene Pyrénéo-Provençal orogenic belt in southern Provence.

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Structural inversion of the North Ligurian margin: results from the SEFASILS experiment

10.5194/egusphere-egu21-9759 ◽

2021 ◽

Author(s):

Albane Canva ◽

Jean-Xavier Dessa ◽

Alessandra Ribodetti ◽

Marie-Odile Beslier ◽

Laure Schenini ◽

...

Keyword(s):

Continental Slope ◽

Sedimentary Cover ◽

Fault System ◽

Wide Angle ◽

Ligurian Sea ◽

Seismic Reflection Data ◽

Alpine Belt ◽

The North ◽

Reflection Data ◽

Ligurian Basin

The north Ligurian margin is a stretched continental margin located at the junction of the Western Mediterranean Sea and the Alpine belt. This region underwent several phases of contrasting deformation styles. The Ligurian basin opened from late Oligocene to early Miocene times, as a result of a back-arc extension induced by the rollback of the subducted Apulian plate. Since then, it has been evolving in the immediate vicinity of the active Alpine orogen, in a regional compressional setting between the Corsica-Sardinia continental block and mainland Europe.Nowadays, continuous seismic activity, with mainly reverse focal mechanisms, is recorded in the northeastern part of the Ligurian Basin. It is attributed to the compressional phase at work in the Gulf of Genoa since about 5 Myrs, which led to a significant uplift of the north margin documented by a vertical offset of the Messinian stratigraphic markers by more than 1000 m offshore Imperia. Although active seismogenic faults are still poorly known, a fault system outcropping at the foot of the continental slope, offshore Liguria and the French Riviera, is suspected from previous joint high-resolution seismic reflection data interpretation and sismotectonic studies.The SEFASILS project (Seismic Exploration of Faults And Structures In the Ligurian Sea) aims to better understand the mechanisms of the ongoing tectonic inversion of the margin and the crustal-scale tectonic structures &#8211;active or not&#8211; marking its evolution.&#160; We also aim to better characterize the sharp transition from the South Alpine belt to the Ligurian basin. Acquiring quality deep seismic data in the Ligurian Sea is challenging due to the complexity of structures beneath the margin and to the screening effect of the thick Messinian evaporitic series interlayered in the sedimentary cover farther seaward. To this end, joint acquisitions of deep, long-streamer multichannel seismic (MSC) reflection data and dense sea-bottom wide angle refraction data (WAS) have been carried out along a 150 km long profile offshore Nice, perpendicularly to the basin&#8217;s axis.The MCS data, thanks to pre- and post-stack migration, highlight faults at the foot of the continental slope rooting deeper than the salt decollement level. A first arrival travel time tomographic inversion of the wide angle data allowed us to build a velocity model of the study area reaching down to the uppermost mantle. Here, we present the results obtained from the joint analysis of MCS and WAS data. On the southern part of our profile some deep reflectivity, closely mirrored by the 7 km/s tomographic isovelocity, likely corresponds to the Moho. It is lost to the north, where shallower reflectivity, which could be interpreted as the base the thick sedimentary cover, coincides with the 5 km/s isovelocity. These two features are separately observed on both sides of what appears to be a major structural discontinuity between two contrasting basement domains, coinciding with an anomalously large salt diapiric complex in the sedimentary cover, also observed farther east in the basin. Such observations and their potential consequences will be discussed, in the light of previous regional studies.

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Fault interpretation in seismic reflection data: an experiment analysing the impact of conceptual model anchoring and vertical exaggeration

Solid Earth ◽

10.5194/se-10-1651-2019 ◽

2019 ◽

Vol 10 (5) ◽

pp. 1651-1662 ◽

Cited By ~ 2

Author(s):

Juan Alcalde ◽

Clare E. Bond ◽

Gareth Johnson ◽

Armelle Kloppenburg ◽

Oriol Ferrer ◽

...

Keyword(s):

Seismic Data ◽

Seismic Reflection ◽

Conceptual Models ◽

Seismic Section ◽

Seismic Reflection Data ◽

Reflection Seismic ◽

Reflection Data ◽

Interpretation Process ◽

Fault Interpretation ◽

The Impact

Abstract. The use of conceptual models is essential in the interpretation of reflection seismic data. It allows interpreters to make geological sense of seismic data, which carries inherent uncertainty. However, conceptual models can create powerful anchors that prevent interpreters from reassessing and adapting their interpretations as part of the interpretation process, which can subsequently lead to flawed or erroneous outcomes. It is therefore critical to understand how conceptual models are generated and applied to reduce unwanted effects in interpretation results. Here we have tested how interpretation of vertically exaggerated seismic data influenced the creation and adoption of the conceptual models of 161 participants in a paper-based interpretation experiment. Participants were asked to interpret a series of faults and a horizon, offset by those faults, in a seismic section. The seismic section was randomly presented to the participants with different horizontal–vertical exaggeration (1:4 or 1:2). Statistical analysis of the results indicates that early anchoring to specific conceptual models had the most impact on interpretation outcome, with the degree of vertical exaggeration having a subdued influence. Three different conceptual models were adopted by participants, constrained by initial observations of the seismic data. Interpreted fault dip angles show no evidence of other constraints (e.g. from the application of accepted fault dip models). Our results provide evidence of biases in interpretation of uncertain geological and geophysical data, including the use of heuristics to form initial conceptual models and anchoring to these models, confirming the need for increased understanding and mitigation of these biases to improve interpretation outcomes.

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Geohazard detection using 3D seismic data to enhance offshore scientific drilling site selection

Scientific Drilling ◽

10.5194/sd-28-1-2020 ◽

2020 ◽

Vol 28 ◽

pp. 1-27 ◽

Cited By ~ 1

Author(s):

David R. Cox ◽

Paul C. Knutz ◽

D. Calvin Campbell ◽

John R. Hopper ◽

Andrew M. W. Newton ◽

...

Keyword(s):

Site Selection ◽

Seismic Data ◽

Seismic Survey ◽

3D Seismic ◽

Seismic Reflection Data ◽

Scientific Drilling ◽

The North ◽

Reflection Data ◽

3D Seismic Data ◽

Geohazard Assessment

Abstract. A geohazard assessment workflow is presented that maximizes the use of 3D seismic reflection data to improve the safety and success of offshore scientific drilling. This workflow has been implemented for International Ocean Discovery Program (IODP) Proposal 909 that aims to core seven sites with targets between 300 and 1000 m below seabed across the north-western Greenland continental shelf. This glaciated margin is a frontier petroleum province containing potential drilling hazards that must be avoided during drilling. Modern seismic interpretation techniques are used to identify, map and spatially analyse seismic features that may represent subsurface drilling hazards, such as seabed structures, faults, fluids and challenging lithologies. These hazards are compared against the spatial distribution of stratigraphic targets to guide site selection and minimize risk. The 3D seismic geohazard assessment specifically advanced the proposal by providing a more detailed and spatially extensive understanding of hazard distribution that was used to confidently select eight new site locations, abandon four others and fine-tune sites originally selected using 2D seismic data. Had several of the more challenging areas targeted by this proposal only been covered by 2D seismic data, it is likely that they would have been abandoned, restricting access to stratigraphic targets. The results informed the targeted location of an ultra-high-resolution 2D seismic survey by minimizing acquisition in unnecessary areas, saving valuable resources. With future IODP missions targeting similarly challenging frontier environments where 3D seismic data are available, this workflow provides a template for geohazard assessments that will enhance the success of future scientific drilling.

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Tertiary development of the Faeroe-Rockall Plateau based on reflection seismic data

Bulletin of the Geological Society of Denmark ◽

10.37570/bgsd-1995-41-15 ◽

1994 ◽

Vol 41 ◽

pp. 162-180

Author(s):

L O. Baldreel ◽

M.S. Andersen

Keyword(s):

Seismic Data ◽

Seismic Facies ◽

Early Eocene ◽

Ne Atlantic ◽

Seismic Profiles ◽

Norwegian Sea ◽

Reflection Seismic ◽

The North ◽

Rockall Trough ◽

Ne Atlantic Ocean

The Faeroe-Rockall Plateau is located in the NE Atlantic Ocean between Iceland and Scotland and is characterized by a late Paleocene-early Eocene basalt cover, which was extruded in association with the incipient opening of the NE Atlantic. The Faeroe-Rockall Plateau is separated from the NW European continental shelf by the Rockall Trough and the FaeroeShetland Channel, whose nature and age is still debated. Reflector configuration within the basalt allows volcanic seismic facies inteipretation to be carried out. The thickness of the basalt cover is estimated from reflection seismic data. Subbasalt geological structures are identified below subaerially extruded basalt on recently acquired as well as reprocessed seismic profiles. Overlying the basalt are early Eocene and younger Sediments. The distribution of these sedi- . ments is largely controlled by 1) the topography after the cessation of the volcanism, 2) the post volcanic subsidence of the area which is estimated from the depth to the breakpoints located on prim¥)' volcanic escaipments, 3) the Eocene-Miocene compressional tectonics which formed ridge& and minor basins, and 4) bottom currents of Norwegian Sea Deep Water (NSDW) which in the Neogene flowed into the North Atlantic south of the Greenland-Iceland-Faeroe-Scotland Ridg,e. A considerable part of the NSDW flows east and south of th

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The sedimentary markers of the Messinian salinity crisis and their relation with salt tectonics on the Provençal margin (western Mediterranean): results from the “MAURESC” cruise

BSGF - Earth Sciences Bulletin ◽

10.2113/gssgfbull.182.2.181 ◽

2011 ◽

Vol 182 (2) ◽

pp. 181-196 ◽

Cited By ~ 14

Author(s):

Edda Marlène Obone-Zue-Obame ◽

Virginie Gaullier ◽

Françoise Sage ◽

Agnès Maillard ◽

Johanna Lofi ◽

...

Keyword(s):

Sedimentary Cover ◽

Close Relation ◽

Western Mediterranean ◽

Seismic Facies ◽

Normal Faults ◽

Salt Tectonics ◽

Messinian Salinity Crisis ◽

Deep Basin ◽

Seismic Reflection Data ◽

Reflection Data

Abstract The Messinian salinity crisis (MSC) is characterized by gigantic erosion that remodels the margins while a thick, essentially evaporitic and detrital, sedimentary sequence forms in the deep basins. Based on recent (MAURESC, 2003) and earlier (MESEA 1, 1990; MAGIRAA, 1996; GEOBREST, 2002) seismic reflection data, this work brings to light the record of the MSC on the Provençal margin, which has until now been rarely explored from this perspective. Beyond its strictly regional interest, this study fits into a larger synthesis of MSC seismic markers in the Mediterranean and Black Sea marine domain [Lofi et al., 2011] and employs the new nomenclature established on this occasion. The results obtained reveal a Messinian detrital body (CU unit) of 625 metres maximum thickness at the foot of the margin, accumulating at the mouths of the principal canyons. Its form, facies and extension assimilate it to clastic fans, fed by subaerial erosion linked to the MSC. The relative geometry of CU and the Messinian units MU and UU deposited in the deep basin give indications to their chronostratigraphic relations. The deposition of the CU unit is posterior to the basal part of the mobile unit consisting of halite (MU), but contemporary to its top. These results agree with the recent scenarii, which propose that the precipitation of MU in the basin began early, during the lowering of the sea level, and ended at a low level during the MSC [Blanc, 2000; Martin et al., 2001; Sage et al., 2005; Ryan, 2009]. The UU unit surmounts MU and is subdivided into two sub-units with perceptibly different seismic facies : UU1 at the base and UU2 at the summit. UU1 could correspond to a unit containing more halite and/or more clastic material than UU2. The UU1 sub-unit could be partially contemporary to the CU unit. Concerning salt tectonics and its markers, three structural provinces have been evidenced in the sector of study, respectively : an upslope domain in extension (normal faults), an intermediary domain in translation (tabular MU) and a downslope domain in contraction (salt diapirs). These domains are directly linked to the gravity spreading and/or gliding of the brittle sedimentary cover formed by the CU, UU and Plio-Quatenary units and of the mobile level, MU. In the study area, a close relation between the distribution and thickness of CU and salt tectonics has additionally been evidenced at the mouths of the large Messinian canyons, being best expressed where CU is thick.

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Understanding basement fracture architecture in Padra Field, South Cambay Basin, India, through full-azimuth imaging

The Leading Edge ◽

10.1190/tle38040262.1 ◽

2019 ◽

Vol 38 (4) ◽

pp. 262-267

Author(s):

Abhinandan Ghosh

Keyword(s):

Seismic Data ◽

Fracture Network ◽

Velocity Variation ◽

Fracture Detection ◽

Cambay Basin ◽

Fracture Characterization ◽

Seismic Reflection Data ◽

Reflection Seismic ◽

Reflection Data ◽

Basement Reservoirs

Detection and characterization of fractures in reservoirs is of great importance for maximizing hydrocarbon productivity and recovery efficiency. Fractures play an important role in the producibility of unconventional reservoirs such as basement reservoirs. Basement reservoirs are typically found within metamorphic and igneous rock underlying a sedimentary basin, where faulting and tectonic uplift has led to creation of a fracture network. For fracture characterization, integration of information from seismic and nonseismic data such as cores and/or formation microimaging (FMI) logs is essential. Various seismic attributes such as coherency and curvature that are derived from reflection seismic data have been used for more than a decade to detect faults and fractures. In advanced seismic fracture detection technology, automatic fault extraction (AFE) from diffraction seismic data (discontinuity volume) more effectively detects finer scale features in seismic data. We demonstrate the utility of this methodology with an application to seismic data from the Padra Field, South Cambay Basin, India, where the basaltic Deccan Trap forms the basement, and hydrocarbons are produced from basement fractures. Diffraction imaging was applied during processing of the full-azimuth 3D-3C seismic data that cover this field. Using wavefield decomposition in the subsurface local angle domain, separate reflection (specular) and diffraction data volumes were produced. The high-resolution specular stack data imaged a prominent reflector well below the trap top, which is not visible in conventional seismic reflection data. Diffraction stack data also provided higher resolution fault definition and enhanced imaging of spatially consistent geological discontinuities. Subsequent application of the AFE technique to diffraction-imaged data yielded sharp and crisp definition of faults and fractures. We also performed velocity variation with azimuth analysis of 3D angle-azimuth reflection gathers to generate a fracture orientation map. Both sets of results were validated by fractures detected in FMI logs from wells in the field.

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New insights into North Sea tunnel valley infill and genesis from high-resolution 3D seismic data

10.5194/egusphere-egu2020-118 ◽

2020 ◽

Author(s):

James Kirkham ◽

Kelly Hogan ◽

Robert Larter ◽

Ed Self ◽

Ken Games ◽

...

Keyword(s):

High Resolution ◽

North Sea ◽

Seismic Data ◽

3D Seismic ◽

Seismic Reflection Data ◽

North West ◽

The North ◽

Reflection Data ◽

Order Of Magnitude ◽

Subglacial Meltwater

Tunnel valleys are large (kilometres wide, hundreds of metres deep) channels incised into bedrock and soft sediments by the action of pressurised subglacial meltwater. Discovered over a century ago, they are common across large swathes of North-West Europe and North America. However, many aspects of tunnel valley formation, and the processes by which they are infilled, remain poorly understood. Here, we use new high-resolution 3D seismic reflection data, collected by the geohazard assessment industry, to examine the infill lithology and architecture of buried tunnel valleys located in the central North Sea. The spatial resolution of our seismic data (3.125-6.25 m bin size) represents an order of magnitude improvement in the data resolution that has previously been used to study tunnel valleys in this region, allowing us to examine their infill in unprecedented detail. Inside the tunnel valleys, we identify a suite of buried subglacial landforms, some of which have rarely been reported inside tunnel valleys before. These landforms include a 14-km-long system of segmented eskers, crevasse-squeeze ridges, subsidiary meltwater channels and retreat moraines. Their presence suggests that, in some cases, tunnel valleys in the North Sea were reoccupied by ice following their initial formation, casting doubt on hypotheses which invoke catastrophic releases of water to explain tunnel valley creation.

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