Controls on gravity-driven normal fault geometry and growth in stacked deltaic settings: a case study from the Ceduna Sub-basin

2021 ◽  
Vol 61 (2) ◽  
pp. 632
Author(s):  
Monica Jimenez ◽  
Simon P. Holford ◽  
Rosalind C. King ◽  
Mark A. Bunch
Keyword(s):  
Normal Fault ◽  
Passive Margin ◽  
Seismic Survey ◽  
Normal Faults ◽  
Petroleum Systems ◽  
Kinematic Analyses ◽  
Gravity Driven ◽  
Fault Growth ◽  
Constant Growth

Kinematics of gravity-driven normal faults exerts a critical control on petroleum systems in deltaic settings but to date has not been extensively examined. The Ceduna Sub-basin (CSB) is a passive margin basin containing the White Pointer (Albian-Cenomanian) and Hammerhead (Campanian-Maastrichtian) delta systems that detach on shale layers of Albian-Cenomanian and Turonian-Coniacian ages, respectively. Here we present evidence for spatially variable fault growth styles based on interpretation of the Ceduna 3D seismic survey and fault kinematic analyses using displacement–distance, displacement–depth and expansion index methods. We identified faults that continuously grew either between the Cenomanian–Santonian or Santonian and the Maastrichtian located throughout the study area and faults that exhibit growth between the Cenomanian–Maastrichtian that are geographically separated into three areas according to their evolution histories: (i) Northern CSB faults exhibit constant growth between the Cenomanian and Maastrichtian. (ii) Central CSB faults show two dip-linkage intervals between (a) Cenomanian and Coniacian–Late Santonian, (b) Coniacian–Late Santonian and Late Santonian–Maastrichtian segments, respectively. (iii) Central and southern CSB faults exhibit dip-linkage intervals between Cenomanian–early Santonian and Late Santonian–Maastrichtian segments. Our study demonstrates a relationship between the location of the Cenomanian–Maastrichtian faults and their evolution history suggesting constant growth evolution at north and dip linkage at the central and south areas.

Mechanism of Gravity-Driven Deformation Using Sandbox Modeling: A Case Study of The Tarakan Sub-Basin, East Kalimantan

2021 ◽  
Author(s):  
B. Sapiie
Keyword(s):  
Normal Faults ◽  
Additional Information ◽  
Bathymetric Data ◽  
East Kalimantan ◽  
Tectonic Reconstruction ◽  
Gravity Driven ◽  
Sandbox Modeling ◽  
Seismic Sections ◽  
Integrated Study

Based on the observations of subsurface and bathymetric maps, various structural patterns are observed in the Tarakan Basin, especially in the Tarakan and Tidung Sub-basins. One of the hypotheses put forward in this study that the gravity-driven mechanism is responsible to generate the normal faults system and folds -thrust belt in the offshore Tarakan Basin. We conducted an integrated study using palinspatic reconstructions of several seismic sections and an analogue-sandbox modeling to observe and explain this gravity-driven. The deformation modeling, which is controlled by gravity requires special conditions that can trigger the movement. The three main parameters that cause gravity deformation to occur are lithology, loading, and slope. In the case of the Tarakan Basin, modeling was carried out by referring to the results of 2D-seismic palinspatic reconstructions. Besides, the additional information as a basis for modeling is also based on the current topographic and bathymetric data. The tectonic reconstruction is used as a reference for paleo-stress data. In theory, one of the factors determining the occurrence of this mechanism is the presence of detachment. This detachment manifests the over-pressure fluid anomaly in the rock, such as over-pressure shale and salt layers. To simulate the conditions that may closely be like the behavior in this detachment, bead materials were selected in the sandbox modeling. Twenty-two experiments were conducted to test the bead as the materials in this modeling, and more than thirty experiments were carried out to model this case. From more than ten realizations, the model with the closest results to seismic interpretation and palinspastic analyses were chosen. From the results of experiments that have been conducted, the development of thrust faults related to the development of normal faults. This evidence is in line with the deformation of gravity-driven mechanism.

Mid-crustal detachment beneath southern Timor-Leste: seismic evidence for Australian basement in the Timor collision complex (and implications for prospectivity)

2021 ◽  
Author(s):  
T. R. Charlton
Keyword(s):  
Seismic Data ◽  
Passive Margin ◽  
Petroleum Exploration ◽  
Seismic Survey ◽  
Normal Faults ◽  
Thrust Belt ◽  
Collision Complex ◽  
Fold And Thrust Belt ◽  
Timor Leste ◽  
Seismic Sections

Seismic data originally acquired over SW Timor-Leste in 1994 shows two consistent seismic reflectors mappable across the study area. The shallower ‘red’ reflector (0.4-1s twt) deepens southward, although with a block-faulted morphology. The normal faults cutting the red marker tend to merge downward into the deeper ‘blue’ marker horizon (0.5-2.8s twt), which also deepens southward. Drilling intersections in the Matai petroleum exploration wells demonstrate that the red marker horizon corresponds to the top of metamorphic basement (Lolotoi Complex), while the blue marker horizon has the geometry of a mid-crustal extensional detachment. We see no indications for thrusting on the seismic sections below the red marker horizon, consistent with studies of the Lolotoi Complex at outcrop. However, surficial geology over much of the seismic survey area comprises a thin-skinned fold and thrust belt, established in 8 wells to overlie the Lolotoi Complex. We interpret the fold and thrust belt as the primary expression of Neogene arc-continent collisional orogeny, while the Lolotoi Complex represents Australian continental basement underthrust beneath the collision complex. In the seismic data the basal décollement to the thrust belt dips southward beneath the synorogenic Suai Basin on the south coast of Timor, and presumably continues southward beneath the offshore fold and thrust belt, linking into the northward-dipping décollement that emerges at the Timor Trough deformation front. The same seismic dataset has been interpreted by Bucknill et al. (2019) in terms of emplacement of an Asian allochthon on top of an imbricated Australian passive margin succession. These authors further interpreted a subthrust anticlinal exploration prospect beneath the allochthon, which Timor Resources plan to drill in 2021. This well (Lafaek) will have enormous significance not only commercially, but potentially also in resolving the long-standing allochthon controversy in Timor: i.e., does the Lolotoi Complex represent ‘Australian’ or ‘Asian’ basement?

scholarly journals A snapshot of the earliest stages of normal fault development

2021 ◽  
Author(s):  
Ahmed Alghuraybi ◽  
Rebecca Bell ◽  
Chris Jackson
Keyword(s):  
Seismic Reflection ◽  
Spatial Scales ◽  
Normal Fault ◽  
Normal Faults ◽  
3D Seismic ◽  
Seismic Reflection Data ◽  
Reflection Data ◽  
Temporal And Spatial ◽  
Fault Growth ◽  
Lateral Propagation

Despite decades of study, models for the growth of normal faults lack a temporal framework within which to understand how these structures accumulate displacement and lengthen through time. Here, we use borehole and high-quality 3D seismic reflection data from offshore Norway to quantify the lateral (0.2-1.8 mmyr-1) and vertical (0.004-0.02 mmyr-1) propagation rates (averaged over 12-44 Myr) for several long (up to 43 km), moderate displacement (up to 225 m) layer-bound faults that we argue provide a unique, essentially ‘fossilised’ snapshot of the earliest stage of fault growth. We show that lateral propagation rates are 90 times faster than displacement rates during the initial 25% of their lifespan suggesting that these faults lengthened much more rapidly than they accrued displacement. Although these faults have slow displacement rates compared with data compiled from 30 previous studies, they have comparable lateral propagation rates. This suggests that the unusual lateral propagation to displacement rate ratio is likely due to fault maturity, which highlights a need to document both displacement and lateral propagation rates to further our understanding of how faults evolve across various temporal and spatial scales.

scholarly journals Geometric and temporal evolution of extensional growth folds in the Barents Sea, offshore Norway: A tool to understand normal fault growth

2021 ◽  
Author(s):  
Ahmed Alghuraybi ◽  
Rebecca Bell ◽  
Chris Jackson
Keyword(s):  
Surface Deformation ◽  
Barents Sea ◽  
Temporal Evolution ◽  
Normal Fault ◽  
Normal Faults ◽  
Borehole Data ◽  
Growth Strata ◽  
Sedimentary Evolution ◽  
Extensional Strain ◽  
Fault Growth

Extensional growth folds form ahead of the tips of propagating normal faults. These folds can accommodate a considerable amount of extensional strain and they may control rift geometry. Fold-related surface deformation may also control the sedimentary evolution of syn-rift depositional systems; thus, the stratigraphic record can constrain the four-dimensional evolution of extensional growth folds, which in term provides a record of fault growth and broader rift history. Here we use high-quality 3D seismic reflection and borehole data from the SW Barents Sea, offshore northern Norway to determine the geometric and temporal evolution of extensional growth folds associated with a large, long-lived, basement-involved fault. We show that the fault grew via linkage of four segments, and that fault growth was associated with the formation of fault-parallel and fault-perpendicular folds that accommodated a substantial portion (10 – 40%) of the total extensional strain. Fault-propagation folds formed at multiple times in response to periodic burial of the causal fault, with individual folding events (c. 25 Myr and 32 Myr) lasting a considered part of the total, c. 130 Myr rift period. Our study supports previous suggestions that continuous (i.e., folding) as well as discontinuous (i.e., faulting) deformation must be explicitly considered when assessing total strain in extensional setting. We also show changes in the architecture of growth strata record alternating periods of how folding and faulting, showing how rift margins may be characterised by basinward-dipping monoclines as opposed to fault-bound scarps. Our findings have broader implications for our understanding of the structural, physiographic, and tectonostratigraphic evolution of rift basins.

Depth-dependent inversion of normal faults: Structural analysis of the Penobscot 3D seismic volume, offshore Nova Scotia

2021 ◽  
Author(s):  
Alexander Peace ◽  
Christian Schiffer ◽  
Scott Jess ◽  
Jordan Phethean
Keyword(s):  
Nova Scotia ◽  
Structural Evolution ◽  
Passive Margin ◽  
Normal Faults ◽  
3D Seismic ◽  
Petroleum Systems ◽  
Passive Margins ◽  
Kinematic Evolution ◽  
Kinematic Modelling ◽  
Kinematic Mechanisms

<p>The inversion of rift-related faults on passive margins through kinematic reactivation is documented globally. Such structures form an integral part in petroleum systems, provide essential constraints on the kinematic and structural evolution of rifts and passive margins, and can be used as global markers for far-field stresses. Despite the importance of inverted normal faults, the controls on their kinematic evolution, as well as existence and interactions within fault populations are often poorly constrained. Here, we present new structural interpretation and kinematic modelling of an inverted relay ramp structure located offshore Nova Scotia, Canada. This structure is imaged on the Penobscot 3D seismic reflection survey down to ~3.5 s TWTT, and is constrained by two exploration wells. We map two major normal faults that display evidence for inversion in their lower portions (reverse faulting and low-amplitude folding), below ~2.5 s TWTT, though retain a normal offset in upper sections. The wider fault population is dominated by ~ENE-WSW striking normal faults that dip both north and south, while both of the two major faults dip approximately south and are associated with antithetic and synthetic faults. This kinematic dichotomy along the major faults is important as inversion such as this may go unrecognised if seismic data does not image the full depth of a structure. To accommodate such depth-dependent inversion, if both horizons co-existed during inversion, a reduction in volume of the sedimentary package is required between the normal and reverse segments of the fault. In this study, we explore possible kinematic mechanisms to explain inversion structure and the mechanisms accommodating the volumetric changes/ or mass movements required using fault restoration and strain modelling. Our results favour a poly-phase deformation history that can be reconciled with other inversion structures on related passive-margin segments, suggesting these could be widespread processes.</p>

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