scholarly journals Lateral variability of shelf-edge, slope and basin-floor deposits, Santos Basin, offshore Brazil

2019 ◽  
Author(s):  
Michael Steventon ◽  
Christopher Jackson ◽  
David Hodgson ◽  
Howard Johnson
Keyword(s):  
Shelf Edge ◽  
Basin Floor

Deltas vs. Rivers on the Shelf Edge: Their Relative Contributions to the Growth of Shelf-Margins and Basin-Floor Fans (Barremian and Eocene, Spitsbergen)

2000 ◽  
pp. 981-1009 ◽  
Author(s):  
R.J. Steel ◽  
J. Crabaugh ◽  
M. Schellpeper ◽  
D. Mellere ◽  
P. Plink-Bjorklund ◽  
...  
Keyword(s):  
Shelf Edge ◽  
Basin Floor ◽  
Shelf Margins

The arrival of the paleo–Orinoco Delta at Trinidad: The Cruse Formation delta lobes and delivery to deepwater Atlantic

2020 ◽  
Vol 90 (8) ◽  
pp. 938-968
Author(s):  
Ariana Osman ◽  
Ronald J. Steel ◽  
Ryan Ramsook ◽  
Cornel Olariu ◽  
Si Chen
Keyword(s):  
Sea Level ◽  
Late Miocene ◽  
Sediment Supply ◽  
Average Height ◽  
Shelf Edge ◽  
Sea Level Changes ◽  
Orinoco Delta ◽  
Basin Floor ◽  
Shelf Margin ◽  
High Sediment

ABSTRACT Icehouse continental-shelf-margin accretion is typically driven by high-sediment-supply deltas and repeated glacio-eustatic, climate-driven sea-level changes on a ca. 100 ky time scale. The paleo–Orinoco margin is no exception to this, as the paleo–Orinoco River Delta with its high sediment load prograded across Venezuela, then into the Southern and Columbus basins of Trinidad since the late Miocene, depositing a continental-margin sedimentary prism that is > 12 km thick, 200 km wide, and 500 km along dip. The Cruse Formation (> 800 m thick; 3 My duration) records the first arrival of the paleo–Orinoco Delta into the Trinidad area. It then accreted eastwards, outwards onto the Atlantic margin, by shallow to deepwater clinoform increments since the late Miocene and is capped by a major, thick flooding interval (the Lower Forest Clay). Previous research has provided an understanding of the paleo–Orinoco Delta depositional system at seismic and outcrop scales, but a clinoform framework detailing proximal to distal reaches through the main fairway of the Southern Basin has never been built. We integrate data from 58 wells and outcrop observations to present a 3-D illustration of 15 mapped Cruse clinoforms, in order to understand the changing character of the first Orinoco clastic wedge on Trinidad. The clinoforms have an undecompacted average height of 550 m, estimated continental slope of 2.5° tapering to 1°, and a distance from shelf edge to near-base of slope of > 10 km. The clinoform framework shows trajectory changes from strong shelf-margin progradation (C10–C13) to aggradation (C14–C20) and to renewed progradation (C21–24). Cruse margin progradational phases illustrate oblique clinothem geometries that lack well-developed topsets but contain up to 70 m (200 ft) thick, deepwater slope channels. This suggests a high supply of sediment during periods of repeated icehouse rise and fall of eustatic sea level, with fall outpacing subsidence rates at times, and delivery of sand to the deepwater region of the embryonic Columbus channel region. Also, evidence of wholesale shelf-edge collapse and canyon features seen in outcrop strongly suggest that deepwater conduits for sediment dispersal and bypass surfaces for Cruse basin-floor fans do exist. The change to a topset aggradational pattern with a rising shelf trajectory may be linked to increased subsidence associated with eastward migration of the Caribbean plate. The Cruse-margin topsets were dominated by mixed fluvial–wave delta lobes that were effective in delivery of sands to the basin floor. The preservation of a fluvial regime of the delta may have been impacted by basin geometry which partly sheltered the area from the open Atlantic wave energy at the shelf edge. Ultimately, understanding shelf-edge migration style as well as process-regime changes during cross-shelf transits of the delta will help to predict the location of bypassed sands and their delivery to deepwater areas.

scholarly journals Description and interpretation of fault-related sedimentation and controls on shelf-edge deltas: implication on sand transportation to the basin floor in parts of Eastern Niger Delta

2020 ◽  
Vol 10 (4) ◽  
pp. 1367-1388
Author(s):  
David O. Anomneze ◽  
Anthony U. Okoro ◽  
Norbert E. Ajaegwu ◽  
Eliseus O. Akpunonu ◽  
Izuchukwu I. Obiadi ◽  
...  
Keyword(s):  
Niger Delta ◽  
Shelf Edge ◽  
Basin Floor

Depositional architecture and sequence stratigraphy of the Karoo basin floor to shelf edge succession, Laingsburg depocentre, South Africa

2011 ◽  
Vol 28 (3) ◽  
pp. 658-674 ◽  
Author(s):  
S.S. Flint ◽  
D.M. Hodgson ◽  
A.R. Sprague ◽  
R.L. Brunt ◽  
W.C. Van der Merwe ◽  
...  
Keyword(s):  
South Africa ◽  
Sequence Stratigraphy ◽  
Shelf Edge ◽  
Karoo Basin ◽  
Basin Floor ◽  
Depositional Architecture

scholarly journals The effects of differential compaction on clinothem geometries and shelf-edge trajectories

Geology ◽  
2019 ◽  
Vol 47 (11) ◽  
pp. 1011-1014 ◽  
Author(s):  
Daan Beelen ◽  
Christopher A.-L. Jackson ◽  
Stefano Patruno ◽  
David M. Hodgson ◽  
João P. Trabucho Alexandre
Keyword(s):  
Sea Level ◽  
Sedimentary Facies ◽  
Sediment Supply ◽  
Shelf Edge ◽  
Fine Grained ◽  
Vertical Extension ◽  
Basin Floor ◽  
Sediment Transfer ◽  
Stacking Patterns ◽  
Basin Margin

Abstract The geometry of basin-margin strata documents changes in water depth, slope steepness, and sedimentary facies distributions. Their stacking patterns are widely used to define shelf-edge trajectories, which reflect long-term variations in sediment supply and relative sea-level change. Here, we present a new method to reconstruct the geometries and trajectories of clinoform-bearing basin-margin successions. Our sequential decompaction technique explicitly accounts for downdip lithology variations, which are inherent to basin-margin stratigraphy. Our case studies show that preferential compaction of distal, fine-grained foresets and bottomsets results in a vertical extension of basin-margin strata and a basinward rotation of the original shelf-edge trajectory. We discuss the implications these effects have for sea-level reconstructions and for predicting the timing of sediment transfer to the basin floor.

scholarly journals Late Jurassic evolution of the Jameson Land Basin, East Greenland – implications of the Blokelv-1 borehole

2018 ◽  
pp. 149-168
Author(s):  
Morten Bjerager ◽  
Peter Alsen ◽  
Jørgen A. Bojesen-Koefoed ◽  
Tove Nielsen ◽  
Stefan Piasecki ◽  
...  
Keyword(s):  
Sea Level ◽  
Field Studies ◽  
Upper Jurassic ◽  
Shelf Edge ◽  
Block Rotation ◽  
Sea Level Changes ◽  
Relative Sea Level ◽  
East Greenland ◽  
Half Graben ◽  
Basin Floor

Data from the recently drilled, fully cored Blokelv-1 borehole and previous cored boreholes in the Upper Jurassic of Jameson Land, central East Greenland, are integrated with published field studies to address the depositional evolution of the Jameson Land Basin in the Oxfordian–Volgian. In Jameson Land, the succession represents a marine shelf-to-basin transect in a W–SW-dipping half-graben. Laminated organic-rich mudstones were deposited in the central deep parts of the basin and grade up-slope into bioturbated sandy mudstones. Extensive shallow marine – deltaic sand prograded from the western and northern basin margins and formed prominent sandy shelf-edge wedges. Sand-rich density flows initiated by periodic collapse of the shelf edge deposited massive sand bodies on the slope and basin floor; these sands were prone to post-burial remobilisation to form injectite bodies. Basin evolution was controlled both by relative sea-level changes, typically correlatable with regional and global sea-level curves, and by rift tectonics. During periods with high relative sea level, the organicrich muddy facies onlapped the sandy shelf environments; such periods of basinal expansion and onlap are recorded in the lower Oxfordian (Q. mariae Chronozone), the middle–upper Oxfordian (C. tenuiserratum – A. glosense Chronozones) and uppermost Oxfordian – upper Kimmeridgian (A. regulare – A. autissiodorensis Chronozones); the deepening, transgressive trend culminated in the mid-Kimmeridgian (A. eudoxus Chron). Marked progradation of the sandy shelf and associated deposition of gravity-flow sands on the slope and basin floor occurred in the early Oxfordian (C. cordatum Chron), the middle Oxfordian (C. densiplicatum Chron), the late Oxfordian (A. serratum Chron) and the early Volgian (P. elegans Chron). The basin architecture reflects periodic differential subsidence on the W- to SW-dipping fault block. The lower to middle Oxfordian is highly condensed in the east (<10 m) and thickens markedly towards the west (>300 m), reflecting accumulation during rift/fault-controlled block rotation. The upper Oxfordian – Kimmeridgian, in contrast, shows a broadly symmetrical distribution and records uniform regional subsidence.

scholarly journals Lateral variability of shelf-edge and basin-floor deposits, Santos Basin, offshore Brazil

2020 ◽  
Vol 90 (9) ◽  
pp. 1198-1221
Author(s):  
Michael J. Steventon ◽  
Christopher A-L. Jackson ◽  
David M. Hodgson ◽  
Howard D. Johnson
Keyword(s):  
Mass Movement ◽  
Three Dimensional ◽  
Outer Shelf ◽  
Continental Margins ◽  
Shelf Edge ◽  
Sequence Stratigraphic ◽  
Se Brazil ◽  
Basin Floor ◽  
Shelf Margin ◽  
Upper Slope

ABSTRACT Construction of continental margins is driven by sediment transported across the shelf to the shelf edge, where it is reworked by wave, tide, and fluvial processes in deltas and flanking clastic shorelines. Stalling of continental-margin progradation often results in degradation of the outer shelf to upper slope, with resedimentation to the lower slope and basin floor via a range of sediment gravity flows and mass-movement processes. Typically, our understanding of how these processes contribute to the long-term development of continental margins has been limited to observations from broadly two-dimensional, subsurface and outcrop datasets. Consequently, the three-dimensional variability in process regime and margin evolution is poorly constrained and often underappreciated. We use a large (90 km by 30 km, parallel to depositional strike and dip, respectively) post-stack time-migrated 3D seismic-reflection dataset to investigate along-strike variations in shelf-margin progradation and outer-shelf to upper-slope collapse in the Santos Basin, offshore SE Brazil. Early Paleogene to Eocene progradation of the shelf margin is recorded by spectacularly imaged, SE-dipping clinoforms. Periodic failure of the outer shelf and upper slope formed ca. 30-km-wide (parallel to shelf-margin strike) slump scars, which resulted in a strongly scalloped upper-slope. Margin collapse caused: 1) the emplacement of slope-attached mass-transport complexes (MTCs) (up to ca. 375 m thick, 12+ km long, 20 km wide) on the proximal basin floor, and 2) accommodation creation on the outer shelf to upper slope. This newly formed accommodation was infilled by shelf-edge-delta clinoforms (up to 685 m thick), that nucleated and prograded basinward from the margin-collapse headwall scarp, downlapping onto the underlying slump scar and/or MTCs. Trajectory analysis of the shelf-edge deltas suggests that slope degradation-created accommodation was generated throughout the sea-level cycle, rather than during base-level fall as would be predicted by conventional sequence-stratigraphic models. Our results highlight the significant along-strike variability in depositional style, geometry, and evolution that can occur on this and other continental margins. Coeval strata, separated by only a few kilometers, display strikingly different stratigraphic architectures; this variability, which could be missed in 2D datasets, is not currently captured in conventional 2D sequence stratigraphic models.

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