Basin Research最新文献

Chlorite minerals, mainly in the form of clay coats, play a critical role in determining the reservoir quality of siliciclastic rocks. They can positively influence reservoir quality by preserving porosity during deep burial, but they can also play a negative role by reducing permeability through pore filling. The main aim of this research is to determine the optimal conditions for chlorite growth in sedimentary basins. This study investigates the Lower Cretaceous turbidite sandstone of the Agat Formation in the North Sea. We used a source-to-sink approach to investigate the impact of sediment source composition, chemical weathering and depositional environment on chlorite formation. Understanding the interplay between these processes can help refine exploration and exploitation strategies, optimise hydrocarbon recovery, and reduce exploration risks. Representative samples from two hydrocarbon fields (the Duva and Agat fields) were investigated using petrography, geochemistry, heavy mineral identification and quantification, and U–Pb geochronology of detrital zircons. Our results show a strong heterogeneity in the sediment provenance between the two turbidite systems. In the Duva field, the sandstone is derived from a mixture of mafic and felsic sources, producing Fe-rich sediments. Intense chemical weathering generates fine fraction materials rich in kaolinite, vermiculite, and hydroxy-interlayered clays, which are transported into shallow marine settings. Subsequent interaction with seawater results in the formation of glauconitic materials, Fe-illite, and phosphatic concretions. These Fe-rich materials are remobilised into deep marine settings, providing precursors for the development of authigenic Fe-clays such as berthierine and chlorite. Conversely, in the Agat field, the sandstone is predominantly sourced from felsic rocks that underwent low chemical weathering, producing sediment rich in quartz and feldspar with a low amount of clays. With few Fe-rich materials transported into the basin, the development of chlorite in the Agat field was less pervasive. Basin configuration and depositional environment exerted additional control on chlorite distribution. In the confined turbidite system (e.g. Duva field), chlorite is typically found as coating, whereas in less confined turbidite systems (e.g. Agat field) chlorite shows complex distribution related to depositional environment and dewatering processes. Our findings demonstrate the importance of considering the entire sediment routing system, from source to sink, when predicting chlorite occurrence and its impact on reservoir quality in deep marine settings. This integrated approach can guide exploration and development efforts in deepwater clastic reservoirs.

The internal fault architecture is crucial in assessing the significance of faults in fluid migration. The development of overlapping zones between segments and subsidiary structures is characteristic of a strike–slip faults. However, their internal architectures and roles in fluid migration are still poorly understood. The Tarim Basin's recently identified strike–slip faults imply that the petroleum resource is hosted in caves that were formed by subsequent dissolution after the formation of the fault zones in carbonate rocks, indicating that the internal fault architecture may be closely linked to the accumulation of petroleum. We investigated the architecture of the strike–slip fault zone using field, geochemical, seismic and well-logging data. The results revealed that the strike–slip faults contain flower-like structures in their vertical profiles and an en échelon and ‘X’ conjugate pattern in their horizontal slices. The fault core may become more complex because of the flower structure as fault breccia, slip surfaces, hydrothermal veins, dissolved pores and caves develop, and the damage zone contains multiple stages of fractures with high dip angles. Compared with ‘X’ pattern conjugate faults, NE-trending strike–slip faults have a more developed and connected fault zone. The fault core acts as a fast conduit for fluid transport and experiences significant elemental losses, and the elemental variations in the damage zone may relate in long-term and relatively lower-level fluid–rock interactions. Three fault zone architecture models were created, namely, a releasing bend, a restraining bend and a single segment, and their controlling impacts on fluid migration were addressed accordingly. Our findings imply that fluid migration and accumulation are more favourable at the releasing bend than at the restraining bend and single segment.

Sedimentary basins adjacent to subduction-related continental arcs provide important archives for deciphering the intricate history of convergent plate margins. The east-west trending Gangdese magmatic arc was one of the most predominant topographic features located at the southern margin of Tibet before the arrival of the Indian plate. However, the detailed Cretaceous growth and evolution across the arc system remains ambiguous. Stratigraphy of the adjacent Xigaze forearc basin provides a well-preserved and well-exposed record of the tectonic and magmatic evolution of the arc throughout the Cretaceous period. We report new stratigraphic, sedimentological, geochronological, and provenance analyses of the Quarry Ridge sandstone in the Xigaze forearc basin along with compiled zircon U-Pb ages (n = 9674) and Lu-Hf isotopic signatures (n = 3389) from the Gangdese arc, the Xigaze forearc basin, and the Linzhou retroarc foreland basin to reconstruct the Early to middle Cretaceous magmatism and uplift of the Gangdese arc and concurrent sedimentary responses within both basins. Exhumation of the arc initiates at around 113 Ma suggested by arc detritus first arriving in both basins. Another episode of inferred uplift occurs at around 108 Ma, which resulted in coarse-grained sedimentation in adjacent basins, preventing Central Lhasa detritus from reaching the Xigaze forearc basin further south and a facies and provenance change within the Linzhou basin. Finally, a third episode at around 101 Ma is reflected by deposition of the progradational Quarry Ridge clastic succession and marks the initiation of a substantial coarse-grained depositional stage in the Xigaze forearc basin. Our study emphasizes the connection between coarse-grained deposition in the forearc basin and arc magmatism and uplift. This study also provides an orogen-scale assessment of the history of arc magmatism, uplift, and sedimentation across the Gangdese magmatic arc system, which supports interpretations that Tibet was already characterized by complex and substantial topographic relief during the Cretaceous before the collision between the Indian and Eurasian plates.

The conglomerates preserved in alluvial fans in the Swiss Molasse basin provide crucial insights into the sedimentary dynamics of these routing systems. In particular, the architectural trends and grain sizes of such deposits reveal information on the sediment fluxes and record variations in the intermittency — a proxy for the fan's activity — that indicate on the relative importance of tectonic or climatic controls on sediment production and transport. Here, we calculated intermittencies from sediment transport dynamics using the ratio between the long-term average and the short-term instantaneous unit sediment fluxes during bankfull discharge conditions. For this, we collected grain size data from three palaeo-fan systems that were active through Oligo–Miocene times and that reveal preserved proximal–distal relationships. The three fan systems, which we term the western, central and eastern fans, show significant differences in their long-term sediment budget but equivalent magnitudes of the sediment transport dynamics expressed through the intermittency factor. The eastern fan records a low long-term sediment flux (5.7 km² Myr⁻¹), which needed the fan to be active during ca. 8 h yr⁻¹ (intermittency factor of 0.89 × 10⁻³). The western fan reveals a higher long-term sediment flux (16.2 km² Myr⁻¹), which could have accumulated during ca. 16 h yr⁻¹ (intermittency factor of 1.83 × 10⁻³), thereby reflecting a more active system. The central fan records the largest long-term sediment flux (40.3 km² Myr⁻¹), where ca. 57 h yr⁻¹ of sediment transport would be required to deposit the supplied material (intermittency factor of 6.53 × 10⁻³), thus representing the most active system. By relating these characteristics to the regional exhumation history, we consider that the central fan mainly recorded the transient response of the Alpine surface to the break-off of the European mantle lithosphere slab. Contrarily, the western and eastern fans were formed during the Alpine evolution when steady-state conditions between uplift and erosion were reached and when sediment fluxes to the basin were lower. Despite differences in the tecto-geomorphic and climatic boundary conditions, our data suggest that these Oligo–Miocene megafans could accomplish their mean annual sediment transport work within a few hours or days per year.

The Upper Jurassic–Lower Cretaceous sedimentary rocks in the Eastern Barents Sea Basin are up to 2 km thick and represent one of the least studied Arctic intervals. Here, for the first time, we present a detailed analysis of 43,000 km of 2D seismic profiles, as well as well-log and core data from 24 offshore wells with the aim to create a comprehensive sequence stratigraphic framework that can be integrated with the rest of the basin. Results show that (1) seven third-order sequences and five types of clinoforms can be identified based on integrated seismic and well data. The age of each sequence was established based on published biostratigraphic investigations along with new dinocyst interpretations included in this study; (2) the deep marine basin was gradually filled with sediments coming from north, east and south as a response to HALIP, Canada Basin opening and Cimmerian uplift of Novaya Zemlya, and was preserved only in the south-western part of the Barents Sea Basin at the end of Early Cretaceous and (3) both Eastern Barents Sea and West Siberia Basin share similarities in sedimentary environments and tectonic setting, though the spatial distribution of clastic reservoirs in Upper Jurassic and Lower Cretaceous mega-sequence heavily depends on the source areas that require more provenance focused research. The results presented here can be used in further regional exploration in the area and to better understand the geodynamic evolution of the Greater Barents Sea Basin.

Continental margins develop long submarine slopes, linking the shallow shelves along the continental landmasses to the deep abyssal plain. They are the results of a complex interaction between destructive and constructive processes, although by and large they are sites of deposition. There is a great amount of variation between the length, height, smoothness, gradient and variation thereof between the slope profiles; however, there is also recurring similarity in their shape. The similitude has suggested systematic relationships between the shape and the processes forming them, and led to studies on geomorphological categorisation based on curvatures. The potential for prediction of along-strike variations and connection between morphology and sedimentary process is herein approached through broadening the mathematical functions used, detailed measurement, observation and curve-fitting of over 150 passive continental margins. Previously, three functions have been used to categorise submarine slopes. The present study finds that four mathematical functions closely match the slopes: Linear, Gaussian, exponential and quadratic (positive and negative/inverse), and reveals that the fourth slope, the quadratic, is by far the most common. While exponential and quadratic slopes are similar there is a crucial difference in the way in which the angle of the slope changes. This study suggests that quadratic slopes represent systematically decreasing sediment deposition with distance, previously attributed to exponential slopes. Exponential slopes meanwhile, represent slope readjustment profiles with upper sediment bypass and lower slope aggradation. Linear slopes, which form the longest low-angle slopes, form in response to high sediment input. Abrupt shelf-edges form in shallower water and develop longer slope aprons, suggesting formation from erosional processes. This implies that the quintessential sigmoidal (s-shaped, Gaussian function) slope, with a smooth rollover, represents the fundamental depositional slope profile.

The Zagros foreland basin is an important sedimentary archive for the tectonic and paleoclimatic evolution of the Zagros Mountains and the entire Neotethyan Arabia–Iran collision zone. By combining new geochemical high-resolution whole rock XRF data with clay mineralogy and soluble salt geochemistry we propose an evolution of the sedimentary environment in the Lurestan arc from the Serravallian to the early Pleistocene, closing a gap in understanding the complex exhumation history of the central Zagros mountain belt. An increase in ultramafic sedimentary input indicates a shift from provenance 1 to provenance 2 by ophiolite exhumation at ca.10 Ma in the Imbricated Zagros north of the Lurestan arc. Our data further indicates that the sedimentary environment of parts of the Lahbari Mb within the Lurestan arc represents a piedmont deposition of fine-grained alluvial fans and siltstones with aeolian contribution deposited under hyper-arid climate conditions. These represent provenance shift 3 and were likely sourced from evaporites of the underlying Gachsaran Fm and fluvial deposits of the Lower Aghajari Mb (provenance 1 and provenance 2), uplifted by the Mountain Front Flexure at around 5.6 Ma. Combining XRF whole rock data with clay mineral data refines formation conditions of the clay minerals in the foreland basin such as palygorskite, which is revealed to be authigenic in origin in the Lower Aghajari Mb. as a function of varying Mg-content due to variations of erosion of the ultramafic and mafic rocks in the Imbricate Zagros belt. Palygorskite in the Lahbari Member is likely both inherited from the Neogene Gachsaran evaporites as well as of authigenic origin.

Higher secondary porosity was observed in the centre of a sandstone unit in the Eocene Shahejie Formation fan delta front sandstones from the Bozhong Depression, Bohai Bay Basin. This differs from past studies showing secondary porosity mainly in the marginal parts of sandstones adjacent to shales. This study utilized reactive transport models involving low-molecular-weight organic acids (LMWOA) to discuss potential processes resulting in the contrary distribution of secondary porosity. An interface model simulating LMWOA diffusion from adjacent shales to the sandstone resulted in secondary porosity in sandstones adjacent to shales. In contrast, an advection model simulating advective transport of LMWOA parallel to the sandstone bedding successfully generated higher secondary porosity in the central part. The central part of the sandstone exhibited better grain sorting (greater depositional porosity) and significantly less early carbonate cements compared to the marginal sandstone parts. Consequently, the central part had greater porosity prior to the dissolution through LMWOA. The initially higher porosity in the central part allowed for a higher advective flux of LMWOA-rich water and associated lower pH, resulting in decreased oligoclase saturation, higher oligoclase dissolution rates and ultimately higher secondary porosity. This study indicates that grain sorting during sediment deposition, early carbonate cementation, LMWOA production in adjacent shales, and advection processes collectively control the diagenetic reactions and the distribution of secondary porosity in sandstones.

Geophysical and geological research in the Ulleung Basin has been ongoing since the 1970s, involving continuous seismic acquisition and multiple well-drilling projects. This study utilized an integrated quantitative approach with conventional seismic interpretation based on recent trends to understand the history of the shelf-margin development and individual controls that may have influenced each period in the Ulleung Basin. Quantitative analysis was conducted by measuring the progradation (P_se), aggradation (A_se) and sediment influx (Fc) of individual shelf margins in seven dip-oriented seismic profiles, and calculating the shelf-edge gradient (α_se) and the P/A ratio. Based on these data and the ratio of accommodation to sediment supply (A/S ratio), which was interpreted from the stratal stacking pattern, five shelf-edge trajectory types were defined and assigned to each shelf margin. By considering individual controls (eustatic fluctuations, sediment supply and tectonic events), we defined the three evolution intervals of the Ulleung Basin during the Middle Miocene to Late Miocene (15 to 6.5 Ma): (1) the upper Middle Miocene (15 to 11.63 Ma) characterized by a moderate sediment supply and high aggradation margin induced by rapid subsidence, (2) the lower Upper Miocene (10.8 to 10 Ma) as a high sediment supply and low aggradation margin associated with reworked sediments from the uplifted Dolgorae Thrust and (3) the uppermost Miocene (9.2 to 6.5 Ma) characterized by a low sediment supply and low aggradation margin experiencing sediment starvation. A comparison with worldwide continental margins indicated that the Ulleung Basin formed under a relatively low rate of progradation (low sediment supply; 4.79 km/Myr) and a high rate of aggradation (high shelf accommodation; 361.04 m/Myr) condition. The SW margin of the Ulleung Basin provides a unique example of understanding stratigraphic architecture variations under changing stress regimes of back-arc setting (extensional to compressional) and understanding of individual controls that influence margin development.