Basin Research - Volume 33, Issue 6, 2021

The Rosebank Field is located in the Faroe‐Shetland Basin and hosts hydrocarbons within siliciclastic sediments interlayered with volcanic packages of the Late Paleocene to Early Eocene aged Flett Formation. Within this study the volcanic sequences are investigated based on an integrated appraisal of available drill cuttings, sidewall cores, core and wireline logs including image log and geochemical logs from eight wells supported by 3D seismic data. The Rosebank lower (RLV), middle (RMV) and upper (RUV) volcanic sequences are inter‐layered with Colsay Member (C1–C4) fluvial to shallow marine siliciclastic intervals. A comprehensive cross‐field borehole based lithofacies interpretation is presented characterising simple, compound and ponded effusive lava flow facies along with pillow lavas, invasive lava flows, volcaniclastic sediments and complex lava–sediment interactions. Geochemical analyses of core, sidewall core, and hand‐picked cuttings spanning the field reveal separate high‐titanium (RHT) and relatively lower‐titanium (RLT) basaltic magma suites. These compositions can be identified and correlated across much of the field utilising geochemical logging data which, in combination with the geochemical analyses, reveals a two‐part stratigraphic sub‐division of each of the RLV, RMV and RUV. Geochemical logging data is also used to define a volcanic proxy (Fe/10+Ti) which utilises the elevated iron (Fe) and titanium (Ti) within all effusive and volcaniclastic basaltic lithologies to differentiate siliciclastic from volcaniclastic sediments where other logging parameters overlap. By comparing the borehole analyses with seismic data, a localised eruptive vent is interpreted within the north of the field. Finally, a cross‐field volcanic model is presented and compared with relevant global field analogues, providing a constrained spatial framework for sub‐surface modelling of inter‐volcanic sequences.

Example of collonade and entablature cooling joints within a ponded lava of the Rosebank Field Upper Volcanics revealed by formation microimager log data alongside a field analogue example from the Isle of Staffa.

Foreland basins are sensitive recorders of spatiotemporal variations in tectonic and climatic forcing associated with an approaching orogenic front. Thus, analysis of foreland deposits and their associated deformation patterns and provenance signals allows assessment of tectonic and sedimentary processes during orogeny, providing clues to past environmental conditions. The Calchaquí region in the southern part of the northwest Argentinian Eastern Cordillera (ca. 25–26°S lat) structurally evolved from a contiguous Paleogene foreland of the Andes into a broken foreland and finally an intermontane basin landscape. This history is recorded in the sedimentary sequences of the Mio‐Pliocene Angastaco and Palo Pintado Formations. We combine sedimentological methods, U‐Pb zircon and K‐Ar glass geochronology, clay mineralogy, and geochemical weathering indices with apatite fission track and (U‐Th‐Sm)/He thermochronology, structural data, and fault modelling to document the stratigraphic response to the fluvial and tectonic processes that followed the formation of the broken foreland. Our observations suggest that fluvial systems in the Calchaquí region repeatedly changed their location and geometry. These fluvial systems were associated with pro‐ and retrograding gravel wedges that most likely formed in response to the structural growth of the Aguas de Castilla and Altos de Viñaco ranges that bound the basin to the east. A compartmentalisation of the foreland with restricted fluvial networks must have occurred by ca. 9 Ma. Our results demonstrate that the reconstruction of stratigraphic architectures constitutes a powerful means to better understand intrabasin tectonics and surface uplift in foreland basins.

The Mio‐Pliocene fluvial systems in the Calchaquí region changed their location and geometry, associated with pro‐ and retrograding gravel wedges in response to intrabasin structural growth of ranges.

Luminescence characteristics of quartz and feldspar allow to discriminate sediments from different source areas. Particularly, sensitivity of optically stimulated luminescence (OSL) and thermoluminescence (TL) signals of quartz and infrared‐stimulated luminescence (IRSL) of feldspar from Quaternary sediments has been used for provenance analysis. These properties change due to source area denudation rates and sediment reworking, which drive the number of burial irradiation‐solar exposure cycles of sediment grains in surface systems. Here, we use for the first time a similar approach to interpret the geomorphic conditions of source areas of Silurian to Triassic siliciclastic sedimentary units of the intracratonic Parnaíba Basin in northeast Brazil. Luminescence measurements were performed on sand grains, and statistical tests were applied to evaluate differences in luminescence properties within and across stratigraphic units. We explored the position of well‐known “110°C” (TL110) and “325°C” (TL325) TL peaks of quartz as proxies to discriminate stratigraphic units with similar lithological assemblages. OSL and TL sensitivities as well as the dominance of the so‐called fast OSL component increase from Silurian to Triassic sedimentary units, while the IRSL sensitivity decreases towards younger stratigraphic units. These patterns point to source areas with decreasing denudation rate and higher sediment recycling over basin filling time, leading to decreasing feldspar concentration and quartz luminescence sensitisation. Major changes in luminescence properties coincide with regional unconformities. This is attributed to physical landscape changes leading to shifts in the relief of source areas and basin sediment recycling. The TL110 peak position is similar across stratigraphic units, but the TL325 peak position has significant variation, with values between 324°C and 334°C, allowing its use for stratigraphic discrimination. Changes in OSL and TL characteristics of quartz sediment grains are preserved during long‐term burial (10⁸ Ma), representing a new tool for interpreting basin evolution and to perform stratigraphic analysis of ancient siliciclastic successions.

The analysis of the luminescence sensitivity of optically stimulated luminescence and thermoluminescence signals of sandstone samples from the Parnaíba Basin allowed to identify stratigraphic units and provided new insights about basin evolution.

We propose that a more readily studied, secondary source‐to‐sink (S2S) systems can be formed on direct‐fed margins, in which shelf‐edge deltas are ‘sources’ and deep‐water fans are terminal depositional ‘sinks’, with channels working as delivery ‘conduits’ in between. DionisosFlow stratigraphic‐forward model, coupled to seismic and borehole data from middle Miocene Pearl River margin, are used to explore physical and conceptual linkages of delta‐to‐fan S2S systems, with a focus on the predictability of when and how coarse clastics are delivered from the deltas down to the submarine fans. Middle Miocene Pearl River delta‐to‐fan S2S coupling was stratigraphically enacted in three main ways: (a) deltas that lack downdip fans: high sea level or low sediment supply caused coarse clastics to be stored mainly on inner to outer shelf areas; (b) deltas that are linked downdip to fans: coarse clastics were funneled to submarine fans through slope channels, via direct delta‐to‐fan S2S linkages created by delta overreach at shelf break or channels extending back to shelf‐margin prodeltas; (c) fans that lack updip, coeval deltas: coarse shelf clastics were carried laterally by longshore or other shelf currents, but eventually captured by canyon heads, and then delivered directly to the basin floor. Moreover, our DionisosFlow stratigraphic‐forward models suggest that an oscillation in sea‐level behaviour from slowly falling to rapidly falling would result in a within‐system tract surface occurring within the falling‐stage systems tract. This surface is identified as a significant lower‐order unconformity in its proximal reaches and as a correlative conformity distally. Within‐system tract surfaces are identified by a change in shelf‐edge trajectory regimes from flat to slight falling to moderately falling and in architecture from mixed progradation and degradation to dominant degradation. They are coeval with the onset of the deposition of submarine fans linked updip to deltas or lacking updip deltas, highlighting that sandy deposits can be compartmentalized even within a single systems tract.

(a) Schematic portrayal of the subdivision of a land to ocean S2S system divided into a terrestrial to shallow‐water segment and a submarine segment. Submarine segment of the land to ocean S2S system is composed mainly of shelf‐edge deltas and resultant deep‐water fans on direct‐fed margins, fostering a more readily studied, secondary S2S system (i.e. delta‐to‐fan S2S coupling), in which shelf‐edge deltas are ‘sources’ and deep‐water fans are terminal depositional ‘sinks’, with canyons and/or slope channels working as delivery ‘conduits’ in between. (b) Schematic illustration of three types of delta‐to‐fan S2S coupling extracted from DionisosFlow forward numerical models and 3D seismic data. Note that the existence of delta‐to‐fan S2S linkages guarantees the delivery of coarse detritus to deep‐water areas, but that a lack of delta‐to‐fan S2S linkages prohibits the delivery of coarse detritus to deepwater.

During the early stages of continental extension, isolated rift segments propagate laterally and interact to link‐up at RIZs. In this study, we investigate RIZs in East Africa to decipher the stages of their evolution and gain insights relevant for understanding the evolution of rift systems.

Although much is known about the interaction of faulting and sedimentation within the basins of active segmented continental rift systems, little is known about these processes within the interaction zones of varying geometries that separate the young interacting segments. We address this problem by exploring the non‐volcanic rift interaction zones (RIZ) along the humid, magma‐poor juvenile western branch of the East African Rift System (WB‐EARS). We examine the large‐scale ‘cross‐over’ relief profiles (basin‐to‐basin through‐going profiles extending across RIZs), the spatial patterns of rift‐linking faults (breaching faults), and axial stream morphology. Our results show that: (1) the RIZs are at different stages of their evolution; (2) distinct long‐wavelength 2‐D cross‐over topographic relief shapes, directionality of axial stream flow (sediment routing patterns), and breaching fault patterns characterise RIZs at the various stages of the linkage of interacting rift basins; (3) these stages include unbreached, partially‐breached, recently‐breached, and breached RIZs; (4) deforming RIZs exhibit different styles of directionality of breaching, including a unidirectional (distinct propagator and receiver segments), bi‐directional propagation (both segments act as propagators and receivers), and nucleation and outward propagation of a narrow intra‐RIZ subsidiary rift basin; (5) RIZ breaching is facilitated by overlap rift‐flank deformation, and/or rift tip propagation structures in the form of rift splaying, border fault rotation (rift‐tip rotation), and fault cluster networks and (6) the lateral propagation of breaching faults at the rift tips and flanks, facilitated by localized stress concentrations, is modulated by the extension direction and inherited basement structures. Our findings offer a broader insight into the geometries, structural, and morphological evolution of RIZs, and provide first‐order predictions of the large‐scale sedimentation patterns of humid early‐stage continental rift environments. Our models provide testable hypotheses for linking rift architecture and patterns of early stage sedimentation applicable to ancient rift basins.

The early exhumation history of the Tauern Window in the European Eastern Alps and its surface expression is poorly dated and quantified, partly because thermochronological and provenance information are sparse from the Upper Austrian Northern Alpine Foreland Basin. For the first time, we combine a single‐grain double‐dating approach (Apatite Fission Track and U‐Pb dating) with trace‐element geochemistry analysis on the same apatites to reconstruct the provenance and exhumation history of the late Oligocene/early Miocene Eastern Alps. The results from 22 samples from the Chattian to Burdigalian sedimentary infill of the Upper Austrian Northern Alpine Foreland Basin were integrated with a 3D seismic‐reflection data set and published stratigraphic reports. Our highly discriminative data set indicates an increasing proportion of apatites (from 6% to 23%) with Sr/Y values <0.1 up‐section and an increasing amount of apatites (from 24% to 38%) containing >1,000 ppm light rare‐earth elements from Chattian to Burdigalian time. The number of U‐Pb ages with acceptable uncertainties increases from 40% to 59% up‐section, with mostly late Variscan/Permian ages, while an increasing number of grains (10%–27%) have Eocene or younger apatite fission track cooling ages. The changes in the apatite trace‐element geochemistry and U‐Pb data mirror increased sediment input from an ≥upper amphibolite‐facies metamorphic source of late Variscan/Permian age – probably the Ötztal‐Bundschuh nappe system – accompanied by increasing exhumation rates indicated by decreasing apatite fission track lag times. We attribute these changes to the surface response to upright folding and doming in the Penninic units of the future Tauern Window starting at 29–27 Ma. This early period of exhumation (0.3–0.6 mm/a) is triggered by early Adriatic indentation along the Giudicarie Fault System.

Conceptual model of hydrothermal circulation. (a) Ideal cross section across the future Adriatic palaeomargin in the late Early Jurassic (partly modified from Beltrando et al., 2015; Ferrando et al., 2004), showing the position of the zoomed areas in (b) and (c). Schematic representation of the hypothetical origin and circulation pathways of hydrothermal fluids in the Montalto Dora (b) and Monte Fenera (c) areas; blue and red arrows represent cold descending and hot ascending fluids respectively.

Evidence of hydrothermal activity is reported for the Mesozoic pre‐ and syn‐rift successions of the western Adriatic palaeomargin of the Alpine Tethys, preserved in the Western Southalpine Domain (NW Italy). The products of hydrothermal processes are represented by vein and breccia cements, as well as dolomitization and silicification of the host rocks. In the eastern part of the study area, interpreted as part of the necking zone of the continental margin, Middle Triassic dolostones and Lower Jurassic sediments are crossed by veins and hydrofracturing breccias cemented by saddle dolomite. The precipitation of dolomite cements occurred within the stratigraphic succession close to the sediment–water interface. Despite the shallow burial depth, fluid inclusion microthermometry and clumped isotopes show that hydrothermal fluids were relatively hot (80–150°C). In the western part of the study area, interpreted as part of the hyperextended distal zone, a polyphase history of host‐rock fracturing is recorded, with at least two generations of veins cemented by calcite, dolomite and quartz. Vein opening and cementation occurred at shallow burial depth around the time of deposition of the syn‐rift clastic succession. Fluid inclusion microthermometry on both quartz and dolomite cements indicates a fluid temperature of 90–130°C, again pointing to hydrothermal fluids. Both in Fenera‐Sostegno and Montalto Dora areas, O, C and Sr isotope values, coupled with fluid inclusion and clumped isotope data, indicate that hydrothermal fluids derived from seawater interacted with crustal rocks during hydrothermal circulation. Stratigraphic and petrographic evidence, and U–Pb dating of dolomitized clasts within syn‐rift sediments, document that hydrothermal fluids circulated through sediments from the latest Triassic to the Toarcian, corresponding to the entire syn‐rift evolution of the western portion of the Adriatic palaeomargin. The documented hydrothermal processes are temporally correlated with regional‐scale thermal events that took place in the same time interval at deeper crustal levels.

This contribution investigates the role of a hyperextended rift system in the formation of the Basque–Cantabrian Pyrenees by discussing their present‐day architecture as well as the inherited rift template. Moreover, this work attempts to decipher the onset of reactivation of a hyperextended system and to discuss the related processes during collision. To carry out this study, two regional, crustal‐scale cross‐sections are presented that provide geological and geophysical information and interpretations across the Central and Western Basque–Cantabrian Pyrenees. Moreover, the two sections are restored back to the Cenomanian and Barremian, corresponding to the end of two independent rift stages respectively. The two sections document different structural styles observed along the orogenic belt. The Central section, involving the Iberian and European plates, shows a thin‐skinned structural style, where the Upper Triassic salt acted as a decoupling level between the sedimentary cover and the underlying basement during both extension and reactivation. The Western section, by contrast, crosses only the Iberian plate (i.e., intra‐plate section) and displays a hybrid situation showing both thin‐ and thick‐skinned structural styles that were conditioned by the irregular distribution of Triassic salt. Extensional deformation was localised in the north (i.e., Bay of Biscay) and less important in the south. Despite compressional reactivation, the northern part of the Western section preserves its rift template, which provides key insights to restore the internal part of the Central section. In contrast to the Western section, the Central section shows stacked depocenters, resulting from overprinted Mesozoic rift events that had a first order control on the subsequent reactivation. This study corroborates the importance of rift inheritance during the onset of convergence by reactivating the most distal and weak part of the rift system (i.e., serpentinised mantle) before starting the collision phase. A key learning is that the understanding of the nature and distribution of decoupling levels at a crustal scale is fundamental to reconstruct the structural evolution during the formation and reactivation of a hyperextended rift system.

We reconstruct the fluid flow history of a portion of the inverted Pyrenean rift, the Upper Pedraforca thrust sheet, from the Mesozoic extension to the Alpine orogeny. The results reveal a heterogeneous fluid system, with increasing meteoric water influence during the Eocene‐Oligocene compression.

Fluid systems in inverted rifted margins are challenging to interpret because fractures formed before compression were often reactivated acting as fluid pathways as new ones formed. Deciphering the fracture and fluid flow history in such complex settings has key implications for the prediction of the distribution of mineral resources. As an example, we reconstruct the fluid flow evolution of a portion of the inverted Pyrenean rift, the Upper Pedraforca thrust sheet, from the Mesozoic extension to the Alpine orogeny. We combine structural analysis and petrographic, geochemical and geochronological data obtained from 87 samples of fracture‐filling carbonate cements. During the Late Jurassic‐Early Cretaceous, low‐temperature seawater produced dolomitization of Jurassic and Lower Cretaceous limestones in an extensional setting. During the Early Cretaceous salt‐related extension, formation waters, probably evolved seawater or fluids that interacted with Triassic evaporites, at temperatures from 125 to 149°C migrated through fractures. The formation of breccias within post‐salt rocks in primary weld zones facilitated the upward migration of formation waters that interacted with pre‐salt rocks with high ⁸⁷Sr/⁸⁶Sr ratios. Formation waters at temperatures of 80°C migrated during the emplacement of the Upper Pedraforca thrust sheet in the Late Cretaceous‐Palaeocene. These fluids interacted with Upper Cretaceous Carbonates and/or Triassic evaporites. In contrast, the influence of meteoric fluids increased in shallower positions due to the exhumation of the SE Pyrenees during the Eocene‐Oligocene. Coevally, hot dolomitizing fluids migrated along diapir walls during the formation of secondary welds. Supergene ores documented in diapiric areas worldwide related to meteoric fluids, and the similar meteoric percolation occurred in the Upper Pedraforca thrust sheet, suggest that supergene mineralization could be found in the Pyrenees. Brecciation of rocks in primary weld zones and evaporite detachments, where mineralization accumulate in fractures from basement‐derived fluids, also suggests that similar ores could be found in the Pyrenees.

To better understand the stratigraphic development of sedimentary systems, it is necessary to link the controls on sedimentary processes to the resulting deposits, which in turn allows predictions of stratigraphic architectures at a range of scales. We use a stratigraphic forward model to link the governing parameters to the distribution of deposits within a distributive fluvial system (DFS). The numerical model has been validated against outcrop observations to establish how the depositional processes needed to form the specific sedimentary system have been reproduced. We chose the previously studied Oligocene to Miocene Huesca DFS in northern Spain to investigate and calibrate the model. Additionally, downstream profiles from modern DFS in northern India, and hydrological measurements from the High Island Creek, Minnesota, USA, were used as input parameters for the model in addition to the outcrop data from the Huesca DFS. The resulting model adequately reproduced the real‐world system. Once validated, the analysis of the modelled DFS led to key findings, which expand our understanding of DFS stratigraphic architecture. Reservoir characteristics in radial DFS are dependent on the angle away from the meridian (straight line from the source through the apex to the distal zone of the DFS). The greater the angle is, the coarser the average grain size in the proximal zone is but the finer the average grain size in the medial and distal zones. Lateral variability of net to gross, sandbody thickness and number, and amalgamation ratio is greatest at the transition between the proximal and medial zone and is still significant in the distal part of the DFS. Stratigraphic forward modelling enhanced our understanding of DFS, which leads to reducing risk associated with exploration, production and storage of fluids in subsurface DFS.

Stratigraphic forward models can reproduce distributive fluvial systems at spatial and temporal scale. The model allows full parameter control and sampling coverage with computer capacity as the only limiting factor. Key finding was that lateral variability is greatest at the transition between the proximal and distal zone.

Depositional model of the Cap Beds of the Purbeck Limestone Group or Dorset showing the facies distribution in the Purbeck lake (modified after Underhill, 2002).

Lacustrine carbonate facies distribution is controlled by multiple environmental parameters including climate, hydrology, and tectonic setting, but few published models address this complexity. In this study, seismic and borehole data, integrated with outcrop logging, correlations, and facies models, are used to create a new tectono‐sedimentary model demonstrating how extensional faults, linked by a relay ramp, control distribution of lacustrine carbonate facies in the Upper Jurassic to Lower Cretaceous Purbeck Limestone Group (Wessex Basin, UK). Accumulation occurred in half‐graben sub‐basins south of two extensional east‐west faults, with widespread subaerial emergence of footwall blocks to the north. The lacustrine limestones of the lowest unit of this Group are characterised by in‐situ microbial mounds within bedded inter‐mound packstones‐grainstones. Mounds occur in three depositional intervals separated by paleosols. The distribution of facies indicates more brackish‐water conditions shoreward to the west, and more hypersaline conditions basinward to the east. The relay ramp hosts extensive microbial carbonate buildups formed in response to carbonate‐rich waters sourced from the northern limestone footwall blocks that fed into extensive shallow‐water areas on the low‐angle relay ramp slope.

The Vaca Muerta Formation (Tithonian–early Valanginian) is the main source rock in the Neuquén Basin and the most important unconventional shale resource in South America. In the present study, organic geochemistry, electron microscopy and basin and petroleum system modelling (BPSM) were combined to evaluate source rock properties and related processes along a transect from the early oil (east) to the dry gas (west) window. The unit is characterized by high present‐day (1%–8% average) and original (2%–16% average) total organic carbon contents, which increase towards the base of the unit and basinal (west) settings. Scanning electron microscopy shows that organic pores derived from the transformation of type II kerogen. Isolated bubble pores are typical of the oil window, whereas bubble and densely distributed spongy pores occur in the gas stage, indicating that the maturity gradient exerts strong control on organic porosity. Organic geochemistry, pressure and porosity data were incorporated into a 2D basin petroleum system model that includes the sequential restoration of tectonic events and calculation of compaction trends, kerogen transformation, hydrocarbon generation and estimation of pore pressure through geologic time. The W–E regional model extends from the Agrio Fold and Thrust Belts to the basin border and allows us to evaluate the relationship between thermal maturity and timing of hydrocarbon generation from highly deformed (west) to undeformed (east) regions. Modelling results show a clear decrease in maturity and organic matter (OM) transformation towards the eastern basin margin. Maximum hydrocarbon generation occurred in the inner sectors of the belt, at ca. 120 Ma; long before the first Andean compression phase, which started during the Late Cretaceous (ca. 70 Ma). Miocene compression (15–7 Ma) promoted tectonic uplift of the inner and outer sectors of the belt associated with a reduction in thermal stress and kerogen cracking, as well as massive loss of retained fluids and a decrease in pore pressure. The OM transformation impacted (a) the magnitude of effective porosity associated with organic porosity development, and (b) the magnitude and distribution of pore pressure within the unit controlled by hydrocarbon generation and compaction disequilibrium. BPSM shows a progressive increase in effective porosity from the top to the base and towards the west region related to the original organic carbon content and maturity increasing along the same trend. Overpressure intervals with high organic carbon contents are the most prone to develop organic pores. The latter represent favourable sites for the storage of hydrocarbons in the Vaca Muerta Formation.

Petroleum system modelling showing present‐day maturity (%Ro) of the Vaca Muerta Formation from from the Agrio Fold and Thrust Belt (west) to the NE Platform (east). The increase in TOC0 values from east to west is associated with thickening of the unit, which suggests the potential larger volumes of generated hydrocarbons for the same thermal gradient. The E–W thermal maturity trend is consistent with the decrease in HI and increase in TR values to the west, indicating that in conjunction with increased TOC0, organic pores represent the main control on total porosity in organic‐rich intervals of the unit.

Integrated provenance analysis in the NE Qaidam Basin reveal topographic growth of the southern Qilian Shan during the middle‐late Miocene, from a lower relief region at ca. 13 Ma to a higher relief region at ca. 8 Ma.

The development history of high topography in the northeastern (NE) Tibetan Plateau is essential to test various plateau growth models and understand plateau construction. We present integrated provenance data from the NE Qaidam Basin, south of the Qilian Shan. Results show an increase in carbonate lithics, an increase in Al2O3/SiO2 ratios, a negative shift in εNd values and an appearance of large amounts of Precambrian zircon grains in the period of ca. 13–8 Ma, arguing that the sediment source of the NE Qaidam Basin may have shifted from the East Kunlun Shan to the Qilian Shan during this time interval. We infer that significant topographic growth of the southern Qilian Shan occurred during the middle‐late Miocene. Along with widespread middle to late Miocene deformation records across the Qilian Shan and abruptly shifts on provenance, sedimentary facies and climate indexes in its surrounding basins, present high topography of the NE Tibetan Plateau may have been established since the middle‐late Miocene.

Understanding sedimentary routing systems at continental margins can be challenging in tectonically active regions such as forearc basins. Here, we combine sand modal composition and detrital zircon U‐Pb data from the Kumano Basin and surrounding Nankai Trough region of Japan to explore sedimentation in an active forearc and its linkages to the regional tectonic history. Our analyses are on Miocene‐to‐Pleistocene samples collected by the Integrated Ocean Drilling Program (IODP) at inner and outer forearc basin sites C0009 and C0002, river samples from onshore Honshu, and published results from other Nankai IODP sites. Results show the sediments of many IODP samples are similar to that of the modern rivers. Data from C0009 demonstrate that the early accretionary prism already contained slope basins fed by sediments similar to those in the modern Kumano River by 7.1 Ma. The more distal C0002 section was predominantly fed by a system similar to the modern Yodo River, located to the west‐southwest. We conclude that the section was therefore tectonically transported, in agreement with the ‘mobile model’ of oblique tectonic convergence across SW Japan during late Miocene time. Deposition resumed after a ca. 5.6–3.8 Ma hiatus, with sediments primarily fed from the paleo‐Kumano River, with some input from the paleo‐Tenryu and Kiso/Nagara rivers located to the northeast. Input from the paleo‐Tenryu and Kiso/Nagara rivers was likely re‐routed towards the trench by ca. 1.3 Ma. Sediments similar to those of the distal Yodo River also make up part of the Kumano basin fill and are best explained by erosion of uplifted older accretionary prism sediments along the Megasplay Fault that bounds the forearc basin. Despite the temporal variability in sedimentation routed to the basin, basin‐fill dynamics appear to have been governed primarily by the critical‐wedge style dynamics driven by variations in frontal accretion and in‐ or out‐of‐sequence thrusting response.

Sequential structural restoration of an interpreted and depth‐converted section showing the supra‐salt evolution of the NENB segment in the Nordkapp Basin. The detailed temporal evolution shows the interplay between the base‐salt relief, laterally‐varying syn‐ to early post‐rift LES and prograding sediments. The models shows the salt flow direction (within and out of the plain or three‐dimensions), was influenced by the far‐field stresses during the Triassic‐Jurassic transition and early‐middle Eocene, and by the rotation of the mini‐basins.

Reprocessed, regional, 2D seismic reflection profiles, 3D seismic volumes and well data (exploration and shallow boreholes), combined with 2D structural restorations and 1D backstripping were used to study the post‐salt evolution of the Nordkapp Basin in Barents Sea. The post‐salt evolution took place above a pre‐salt basement and basin configuration affected by multiple rift events that influenced the depositional facies and thickness of Pennsylvanian‐lower Permian‐layered evaporite sequence. Initially, regional mid‐late Permian extension reactivated pre‐salt Carboniferous faults, caused minor normal faulting in the Permian strata and triggered slight salt mobilization towards structural highs. The main phase of salt mobilization occurred during earliest Triassic when thick and rapidly prograding sediments entered from the east into the Nordkapp Basin. In the early‐mid‐Triassic, the change in the direction of progradation and sediment entry‐points shifted to the NW led to rotation of the earlier‐formed mini‐basins and shift of dominant salt evacuation direction to the south. The prograding sediment influx direction, sediment transport velocity and thickness influenced the dynamics of the early to late passive diapirism, salt expulsion and depletion along the strike of the basin. The basin topography resulting from salt highs and mini‐basin lows strongly affected the Triassic progradational fairways and determined the distinct sediment routing patterns. Minor rejuvenation of the salt structures and rotation of the mini‐basins took place at the Triassic–Jurassic transition, due to far‐field stresses caused by the evolving Novaya Zemlya fold‐and‐thrust belt to the east. This rejuvenation influenced the sediment dispersal routings and caused formation of dwarf secondary mini‐basins. The second and main rejuvenation phase took place during likely early‐mid‐Eocene when propagated far‐field stresses from the transpressional Eurekan/Spitsbergen orogeny to the NW inverted pre‐salt normal faults, reactivated the structural highs and rejuvenated the salt structures. The studied processes and study outcomes can be applicable to other evaporite‐dominated basins worldwide.

Pre‐rift salt controls structural style variability within rifts by decoupling sub‐ and supra‐salt faults. However, the way in which this variability controls sediment erosion and dispersal, and facies distributions within the coeval syn‐rift stratigraphic succession, remains poorly known. We here use 3D seismic reflection and borehole data to study the tectono‐stratigraphic development of the Halten Terrace, offshore Mid‐Norway, a salt‐influenced rifted margin formed during Middle to Late Jurassic extension. On the eastern basin margin, the rift structural style passes southwards from an unbreached extensional growth fold dissected by numerous horst and graben (Bremstein Fault Complex [BFC]), into a single, through‐going normal fault (Vingleia Fault Complex [VFC]). This southwards change in structural style is likely related to the pinch‐out of or a change in the dominant lithology (and thus rheology) within a pre‐rift (Triassic) evaporite layer, which was thick and/or mobile enough in the north to decouple basement‐ and cover‐involved faulting, and to permit extensional forced folding. As a result, the salt‐influenced BFC underwent limited footwall uplift, with minor erosion of relatively small horsts supplying only limited volumes of sediment to the main downdip depocentre. In contrast, the VFC, which was directly coupled to basement, experienced significant uplift and extensive footwall erosion. The footwall of this structure also locally underwent salt‐detached gravity gliding and collapse as the pre‐rift detachment was tilted. Our results show that where through‐going normal faults develop along the rift flanks, the presence of a pre‐rift salt layer will suppress the topographic expression of the footwall. The pre‐rift salt layer may however facilitate footwall collapse and limit the volume of sediment supplied to downdip basins. Our results also show that variable topography along the rift flanks facilitated the development of relatively small, localised, intra‐rift flank accommodation that trapped flank‐derived sediment, and which meant basins nearer the rift axis were starved of sediment.

We look at structural variation along the flanks of a rift basin to show how this controls the sediment input and in turn the syn‐rift facies found in the depocentre. The presence of a pre‐rift salt layer can be shown to enhance intra‐slope accommodation space which limits sediment input into deeper basin along with controlling the topographic evolution of rift flanks.

Channel‐levee systems are found in deep and ultra‐deep waters of Equatorial Brazil with a mixed calciclastic‐siliciclastic depositional system.

Distal slope and basin depositional systems in deep waters of the Pará‐Maranhão Basin, Equatorial Brazil, are investigated using a high‐resolution 3D seismic volume, borehole data and multispectral satellite imagery. A Neogene calciclastic submarine fan and a series of channel‐levee systems are analysed at water depths of 100–3,500 m. Channel‐levee systems have sinuous and straight morphologies and are of different sizes. Their origin is related to turbidity flows sourced and funnelled from the carbonate shelf to submarine canyons and gullies, as well as from areas with marked slope instability. A mixed calciclastic‐siliciclastic sediment input is recognised with autochthonous calcarenites and calcilutites comprising the bulk of sediment on the mid and outer continental shelf. Minor amounts of siliciclastic sediment sourced from small rivers occur on the inner shelf. Sedimentation processes of a distally steepened carbonate ramp are discussed considering a general depositional setting dominated by fluctuations in relative sea‐level. Cross‐sectional and planar parameters of mixed calciclastic‐siliciclastic channel‐levee systems are compared to their siliciclastic counterparts. Morphological results show similarities between calciclastic and siliciclastic channel‐levee systems. As a corollary, three types of channel‐levee systems are described: (a) channels related to calciclastic submarine fans, (b) low‐sinuosity, aggradational channels, and (c) high‐sinuosity channels.

Summary conceptual model, graphic facies logs and core examples from the mixed basic and felsic volcanic reservoirs of the Raageshwari Deep Gas Field, NW India.

The Deccan Traps large igneous province (LIP) comprises one of the largest continental flood basalt provinces on Earth with the main phase of volcanism spanning the Cretaceous‐Palaeogene boundary. The oldest volcanism of the province is encountered in the northwest of modern‐day India where Deccan stratigraphy is often buried beneath thick Cenozoic sedimentary sequences. The Raageshwari Deep Gas (RDG) Field, located onshore in the central Barmer Basin, NW India, produces gas from the early Deccan Raageshwari Volcanics which are subdivided into two members, the Agni Member and the overlying Prithvi Member. The RDG comprises a globally important example of a producing volcanic reservoir whilst also offering unique insights into the early volcanism of the Deccan with the aid of extensive high quality sub‐surface data. Within this study, the volcanic facies of the RDG sequences are investigated from five cored intervals (total 160 m). Core‐based facies determinations are compared with geochemical analyses, petrophysical analyses of the cores (density, porosity and permeability), and wireline data including micro‐resistivity borehole images (FMI) and Nuclear Magnetic Resonance (NMR) data. A wireline based volcanic lithofacies scheme is developed and applied to the uncored parts of the sequence which in turn is compared to 3D seismic data. Results of the study reveal the Agni Member to comprise a compositionally bimodal (basalt through to trachyte), dominantly alkaline series with mixed volcanic facies including spectacular felsic ignimbrites, basic‐intermediate simple lava flows, volcaniclastic units and newly identified shallow intrusions. The Prithvi Member in contrast is dominated by tholeiitic basalt compositions with less common basic‐intermediate alkaline compositions and comprises a sequence dominated by classic tabular lava flow facies inter‐digitated with boles, volcaniclastic units, rare compound braided lava facies and evolved tuffaceous ash layers. In one interval of the Prithvi Member, evidence for agglutinated spatter is recorded inferring potential proximity to a palaeo‐eruption site within the area. Comparison between core data and volcanic facies reveals a first order control of volcanic facies on reservoir properties highlighting the importance of volcanic facies appraisal in the development of volcanic reservoirs.

Widespread flooding of the Australian continent during the Early Cretaceous, referred to as the Eromanga Sea, deposited extensive shallow marine sediments throughout the Great Artesian Basin (GAB). This event had been considered ‘out of sync’ with eustatic sea level and was instead solely attributed to dynamic subsidence associated with Australia's passage over eastern Gondwanan subducted material. However, mantle convection models previously used to explain this event have since been shown to overestimate dynamic topography amplitude by a factor of two compared with residual topography estimates. Previous models were also based on a Cretaceous eustatic sea level peak at ca. 90 Ma in conventional eustatic sea level curves; however, more recent estimates of global sea level from ocean basin volume (OBV) suggest this peak may have occurred earlier at ca. 120 Ma. Our work links time‐dependent erosion and deposition with dynamic topography and eustasy to test their contribution to basin development using the landscape evolution code pyBadlands. Our results show that the lower amplitude estimates of dynamic topography derived from pseudo‐compressible mantle flow models better reflect the Cretaceous vertical motions of the Australian continent (ca. 100 m) compared with their incompressible counterparts (ca. 200–400 m). Additionally, our models include the Neogene north‐eastward tilting of Australia, elusive in most previously published geodynamic models. In conjunction with an OBV‐derived sea level curve, our preferred landscape evolution model broadly matches the Cretaceous inundation patterns and first‐order sedimentary sequences in the GAB. The results highlight that the Early Cretaceous inundation of the Australian continent is likely a combination of high global sea levels and the regional effects of dynamic subsidence. Our work provides a framework for a new generation of evolving paleogeographic models at continental scales, while also providing key insights into the viability of existing sea level curves and dynamic topography estimates for reproducing topographic and basin evolution.