Seismic-Scale Geometries and Sequence-Stratigraphic Architecture of Early Cretaceous Syn-Post Rift Carbonate Systems, Presalt Section, Brazil

2020 ◽  
pp. SP509-2019-78
Author(s):  
M. Minzoni ◽  
A. Cantelli ◽  
J. Thornton ◽  
B. Wignall
Keyword(s):  
Early Cretaceous ◽  
Bottom Topography ◽  
Seismic Facies ◽  
Carbonate Production ◽  
Sequence Stratigraphic ◽  
Stratigraphic Architecture ◽  
Platform Margin ◽  
Lacustrine Carbonate ◽  
Sequence Boundaries ◽  
The Impact

AbstractRegional and detailed seismic stratigraphic analyses of Early Cretaceous (Aptian) presalt carbonate sections from offshore Brazil reveal the complex stratigraphic architecture of late- and post-rift lacustrine carbonate systems. The lateral and vertical distribution of calibrated seismic facies within this framework highlights the evolution through time of the carbonate system and bathymetry of the host lacustrine basin. Despite the simple, largely abiotic and microbial components, lacustrine carbonate accumulations formed complex geometries that closely resemble those observed from marine systems, suggesting that a downward tapering carbonate production profile must have occurred. The complexity of the stratigraphic architecture reflects lateral variations in subsidence patterns combined with the interference of the basement topography, palaeo-wind directions, and basinal filling patterns. Well-imaged clinoforms several hundred meters high attest to both the existence of significant lake-bottom topography, locally in excess of 800 meters, and the occurrence of deep water at time of deposition. Platform margin trajectory and vertical and lateral architecture of clinoform packages through time reveal distinct sequence boundaries that can be correlated in detail only locally, demonstrating the impact of syndepositional tectonics, and possibly recurrent isolation of smaller lakes during lowstands. Depositional models from this study fill a gap in current understanding of lacustrine carbonate systems and offer a template for exploration and appraisal of the presalt play.

Using palaeogeographic reconstructions to understand lithological variability within the Early Cretaceous Gage Sandstone and South Perth Shale in the Vlaming Sub-Basin, offshore southern Perth Basin

2014 ◽  
Vol 54 (2) ◽  
pp. 535
Author(s):  
Megan Lech ◽  
Chris Southby ◽  
David Lescinsky ◽  
Luiqi Wang ◽  
Diane Jorgensen ◽  
...  
Keyword(s):  
Early Cretaceous ◽  
Sedimentary Basins ◽  
Sediment Supply ◽  
Seismic Facies ◽  
Depositional History ◽  
Shale Formations ◽  
Sequence Stratigraphic ◽  
Stratigraphic Analysis ◽  
Well Log Analysis ◽  
Breakup Unconformity

The Early Cretaceous Gage Sandstone and South Perth Shale formations are a prospective reservoir-seal pair in the Vlaming Sub-basin. Plays include post-breakup pinch-outs in the Gage Sandstone with the South Perth Shale forming top seal. The Gage reservoir has porosities of 23–30% and permeabilities of 200–1,800 mD. It was deposited in palaeotopographic lows of the Valanginian breakup unconformity and is the lowstand component of the thick deltaic South Perth (SP) Supersequence. To characterise the reservoir-seal pair, a detailed sequence stratigraphic analysis was conducted by integrating 2D seismic interpretation, well log analysis and new biostratigraphic data. Palaeogeographic reconstructions for the SP Supersequence were derived from mapping higher-order prograding packages and establishing changes in sea level and sediment supply. Higher resolution Gage reservoir reconstructions were based on seismic facies mapping. The Gage reservoir forms part of a sand-rich submarine fan system and ranges from canyon confined inner fan deposits to middle fan deposits on a basin plain. Directions of sediment supply are complex, with major sediment contributions from a northern and southern canyon adjacent to the Badaminna Fault Zone. The characteristics of the SP Supersequence differ markedly between the northern and southern parts of the sub-basin due to variations in palaeotopography and sediment supply. Palaeogeographic reconstructions reveal a series of regressions and transgressions leading to infilling of the palaeo-depression. Palaeogeographic reconstructions for the SP Supersequence portray a complex early post-rift depositional history in the central Vlaming Sub-basin. The developed approach is applicable for detailed studies of other sedimentary basins.

Morphology in time and space: how does shape change with sequence stratigraphic architecture?

2020 ◽  
Author(s):  
Judith Sclafani ◽  
Max Christie ◽  
Marjean Cone ◽  
Brooke Roselle ◽  
Audrey Bourne ◽  
...  
Keyword(s):  
Large Scale ◽  
Shape Change ◽  
Low Cost ◽  
Morphological Data ◽  
Morphological Form ◽  
Sequence Stratigraphic ◽  
3D Shape ◽  
Subtidal Environment ◽  
Stratigraphic Architecture ◽  
The Impact

<p>In their seminal work on stratigraphic paleobiology, Patzkowsky and Holland highlighted the need for more morphological data that are placed within a stratigraphic context in order to more robustly study the impact of environmental change on morphological disparity. The ability to collect morphological data within sequence stratigraphic architecture has been limited by technique. As a result, most morphological data are collected from museum specimens, usually without sequence stratigraphic information. We used the photogrammetry technique, Structure-from-Motion, to collect brachiopod morphological data from outcrops in the Late Ordovician Cincinnati Arch (Indiana, Ohio, Kentucky; USA) and quantify morphological change within an established sequence stratigraphic architecture.</p><p>SfM uses 2D photographs taken from different angles to reconstruct a 3D shape. We photographed external valves of brachiopods in the field in 360 degrees (approximately 24 photos per specimen) and used the SfM software ‘Agisoft Metashape’ to make 3D models of those specimens. We exported these models into R and used the package ‘geomorph’ to generate a set of semi-landmarks. We used these to create a morphospace to explore the effects of environment and time on 3D shape.</p><p>Results indicate that brachiopod shells separate in morphospace according to their degree of inflation and roundness. These differences are likely controlled by environmental conditions at each position along a water depth gradient. Additionally, our results are consistent with the previously observed breakdown of the environmental gradient in response to the Richmondian invasion. In particular, for the genera <em>Rafinesquina</em> and <em>Cincinitina</em>, pre-invasion specimens inhabit a larger proportion of morphospace, with more specimens exhibiting an ovular outline. Post-invasion specimens contract in morphospace, exhibiting a more rectangular shape. However, <em>Cincinitina</em> is missing from the offshore environment in the C2 sequence and the deep subtidal environment in the C5 sequence, making it difficult to distinguish the effects of invasion from ecophenotypic variation.</p><p>Ultimately, our study demonstrates that SfM makes gathering 3D morphological data from the field possible. Because this is a low-cost and easily accessible method, possibilities of applying it more broadly within paleobiology abound. Further development of this technique will not only provide a better understanding of the distribution of morphological form within stratigraphic architecture, but also increase the quantity of morphological data from key intervals throughout the Phanerozoic. These data can be stored as a digital archive that could facilitate large-scale meta-analyses as well as education and outreach activities.</p>

scholarly journals Integral Constraints for Momentum and Energy in Zonal Flows with Parameterized Potential Vorticity Fluxes: Governing Parameters

2014 ◽  
Vol 44 (3) ◽  
pp. 922-943 ◽  
Author(s):  
V. O. Ivchenko ◽  
S. Danilov ◽  
B. Sinha ◽  
J. Schröter
Keyword(s):  
Ocean Circulation ◽  
Potential Vorticity ◽  
Channel Model ◽  
Bottom Topography ◽  
Flat Bottom ◽  
Zonal Flows ◽  
Integral Constraints ◽  
Variable Bottom ◽  
Eddy Fluxes ◽  
The Impact

Abstract Integral constraints for momentum and energy impose restrictions on parameterizations of eddy potential vorticity (PV) fluxes. The impact of these constraints is studied for a wind-forced quasigeostrophic two-layer zonal channel model with variable bottom topography. The presence of a small parameter, given by the ratio of Rossby radius to the width of the channel, makes it possible to find an analytical/asymptotic solution for the zonally and time-averaged flow, given diffusive parameterizations for the eddy PV fluxes. This solution, when substituted in the constraints, leads to nontrivial explicit restrictions on diffusivities. The system is characterized by four dimensionless governing parameters with a clear physical interpretation. The bottom form stress, the major term balancing the external force of wind stress, depends on the governing parameters and fundamentally modifies the restrictions compared to the flat bottom case. While the analytical solution bears an illustrative character, it helps to see certain nontrivial connections in the system that will be useful in the analysis of more complicated models of ocean circulation. A numerical solution supports the analytical study and confirms that the presence of topography strongly modifies the eddy fluxes.

scholarly journals Palaeoecological analysis of maximum flooding zones from the Tithonian (Upper Jurassic) of the Kachchh Basin, western India

Facies ◽  
2020 ◽  
Vol 67 (1) ◽  
Author(s):  
Franz T. Fürsich ◽  
Matthias Alberti ◽  
Dhirendra K. Pandey
Keyword(s):  
Upper Jurassic ◽  
Carbonate Content ◽  
Western India ◽  
Rift Basin ◽  
Benthic Assemblages ◽  
Depositional Sequence ◽  
Sequence Stratigraphic ◽  
Stratigraphic Architecture ◽  
Kachchh Basin ◽  
Rich Fauna

AbstractThe siliciclastic Jhuran Formation of the Kachchh Basin, a rift basin bordering the Malagasy Seaway, documents the filling of the basin during the late syn-rift stage. The marine, more than 700-m-thick Tithonian part of the succession in the western part of the basin is composed of highly asymmetric transgressive–regressive cycles and is nearly unfossiliferous except for two intervals, the Lower Tithonian Hildoglochiceras Bed (HB) and the upper Lower Tithonian to lowermost Cretaceous Green Ammonite Beds (GAB). Both horizons represent maximum flooding zones (MFZ) and contain a rich fauna composed of ammonites and benthic macroinvertebrates. Within the HB the benthic assemblages change, concomitant with an increase in the carbonate content, from the predominantly infaunal “Lucina” rotundata to the epifaunal Actinostreon marshii and finally to the partly epifaunal, partly infaunal Eoseebachia sowerbyana assemblage. The Green Ammonite Beds are composed of three highly ferruginous beds, which are the MFZ of transgressive–regressive cycles forming the MFZ of a 3rd-order depositional sequence. The GAB are highly ferruginous, containing berthieroid ooids and grains. GAB I is characterized by the reworked Gryphaea moondanensis assemblage, GAB II by an autochthonous high-diversity assemblage dominated by the brachiopods Acanthorhynchia multistriata and Somalithyris lakhaparensis, whereas GAB III is devoid of fossils except for scarce ammonites. The GAB are interpreted to occupy different positions along an onshore–offshore transect with increasing condensation offshore. Integrated analyses of sedimentological, taphonomic, and palaeoecological data allow to reconstruct, in detail, the sequence stratigraphic architecture of sedimentary successions and to evaluate their degree of faunal condensation.

The impact of Aptian glacio‐eustasy on the stratigraphic architecture of the Athabasca Oil Sands, Alberta, Canada

Sedimentology ◽  
2019 ◽  
Vol 66 (5) ◽  
pp. 1600-1642 ◽  
Author(s):  
Sean C. Horner ◽  
Stephen M. Hubbard ◽  
Harrison K. Martin ◽  
Cynthia A. Hagstrom ◽  
Dale A. Leckie
Keyword(s):  
Oil Sands ◽  
Athabasca Oil Sands ◽  
Stratigraphic Architecture ◽  
The Impact

scholarly journals High-frequency sea-level changes recorded in deep-water carbonates of the Upper Cretaceous Dol Formation (island of Brač, Croatia)

2010 ◽  
Vol 61 (1) ◽  
pp. 29-38
Author(s):  
Damir Bucković ◽  
Maja Martinuš ◽  
Duje Kukoč ◽  
Blanka Tešović ◽  
Ivan Gušić
Keyword(s):  
Sea Level ◽  
Deep Water ◽  
High Frequency ◽  
Upper Cretaceous ◽  
Distal Part ◽  
Preferential Orientation ◽  
Sea Level Changes ◽  
Carbonate Production ◽  
Fine Grained ◽  
Platform Margin

High-frequency sea-level changes recorded in deep-water carbonates of the Upper Cretaceous Dol Formation (island of Brač, Croatia)The upper part of the Middle Coniacian/Santonian-Middle Campanian deep-water Dol Formation of the island of Brač is composed of countless fine-grained allodapic intercalations deposited in an intraplatform trough. Within the studied section 13 beds can be distinguished, each defined by its lower part built up of dark grey limestone with abundance of branched, horizontally to subhorizontally oriented burrows, and the upper part, in which the light grey to white limestone contains larger burrows, rarely branched, showing no preferential orientation. The lower, dark grey, intensively bioturbated levels are interpreted as intervals formed during high-frequency sea-level highstands, while the upper, light grey-to-white levels are interpreted as intervals formed during the high-frequency sea-level lowstands. Cyclic alternation of these two intervals within the fine-grained allodapic beds is interpreted as the interaction between the amount of carbonate production on the platform margin and the periodicity and intensity of shedding and deposition in the distal part of toe-of-slope environment, which is governed by Milankovitch-band high frequency sea-level changes.

scholarly journals Tectono-Stratigraphic Note: Time calibration of late Carboniferous, Permian and Early Triassic Arabian stratigraphy to orbital-forcing predictions

GeoArabia ◽  
2005 ◽  
Vol 10 (2) ◽  
pp. 189-192 ◽  
Author(s):  
Moujahed Al-Husseini ◽  
Robley K. Matthews
Keyword(s):  
Second Order ◽  
Late Carboniferous ◽  
Orbital Forcing ◽  
Third Order ◽  
Depositional Sequence ◽  
Sequence Stratigraphic ◽  
Rosetta Stone ◽  
Time Calibration ◽  
Sequence Boundaries ◽  
Order Sequence

The recent publication of GTS 2004 (Gradstein et al., 2004) provides an opportunity to recalibrate in time the late Carboniferous, Permian and Early Traissic Arabian Stratigraphy (GeoArabia Special Publication 3, Edited by Al-Husseini, 2004) as represented by the rock units in subsurface Interior Oman (Osterloff et al., 2004a, b) and the Haushi-Huqf Uplift region (Angiolini et al., 2004) (Figure). Additionally, sequence stratigraphic models of orbital forcing (Matthews and Frohlich, 2002; Immenhauser and Matthews, 2004) provide new insights in regards to the time calibration of depositional sequences: the “Rosetta Stone” approach. The Rosetta Stone approach predicts that the period of a third-order depositional sequence is 2.430 ± 0.405 my (denoted DS3 and here adjusted to increase the fourth-order ‘geological tuning fork’ from 0.404 to 0.405 my based on Laskar et al., 2004). The present calibration is also tied to the orbital-forcing model developed by R.K. Matthews (in Al-Husseini and Matthews, 2005; this issue of GeoArabia) that predicts that a second-order depositional sequence (denoted DS2) consists of six DS3s that were deposited in a period of about 14.58 my (6 x 2.430 my); the DS2 being bounded by two regional second-order sequence boundaries (SB2) corresponding to sea-level maximum regression surfaces.

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