High resolution imaging of fault reactivation in long-lived extensional setting: a case study from the Exmouth Plateau (NW Australia)

2020 ◽  
Author(s):  
Nico D'Intino
Keyword(s):  
High Resolution ◽  
Confining Pressure ◽  
Data Interpretation ◽  
Fault Analysis ◽  
Fault Reactivation ◽  
Normal Faults ◽  
3D Seismic ◽  
Exmouth Plateau ◽  
Northern Carnarvon Basin ◽  
Nw Australia

<p>Extension in rift zones and passive margins often occur by multiphase normal faulting which usually accommodates several episodes of lithosphere stretching by brittle deformation. In these settings, pre-existing normal faults may reactivate but also new-formed structures may nucleate, with multiple orientations and deformational styles. The various modes of fault growth and nucleation are strongly influenced by several parameters (including orientation and geometry of pre-existing discontinuities, stress orientation and magnitude, strain rates, confining pressure, etc..) with the lithostratigraphy controlling the brittle or ductile litho-mechanic behavior of each unit.</p><p>In this work, we interpreted and analyzed an industrial 3D seismic volume acquired in the Exmouth Plateau, (Northern Carnarvon Basin – offshore NW Australia), where pre-existing Mesozoic normal faults were reactivated during the Cenozoic and controlled the nucleation and growth of the new-formed overlying fault segments. The peculiarity of this system is that the two sets of faults are separated by a ductile interval of shales. The latter acted as decollement level and promoted the formation of prominent faulted anticlines in the overlying brittle sequence; these forced folds are poorly documented in other extensional settings while are common where salt layers are present. In this study, the high-resolution techniques adopted for seismic data interpretation aimed to understand the geometries of faults and their interactions in fine detail. The results of fault analysis suggest that the use of high-quality 3D seismic volumes is very useful to unravel the complex and subtle spatial variability and also the displacement pattern of faults with a limited amount of fault-throw.</p>

Geohazard assessment of submarine salt-related thin-skinned faults: Levant Basin, offshore Israel

2020 ◽  
Author(s):  
May Laor ◽  
Zohar Gvirtzman
Keyword(s):  
High Resolution ◽  
Continental Slope ◽  
Active Faults ◽  
Normal Faults ◽  
3D Mapping ◽  
3D Seismic ◽  
Offshore Area ◽  
Bathymetric Data ◽  
Geohazard Assessment ◽  
Better Than

<p>The Israeli continental slope is dissected by numerous thin-skinned normal faults, deforming the Pliocene-Quaternary section. This extensional faulting is caused by subsurface deformation of the Messinian salt underlying Pliocene rocks. It began in the early Gelasian, at 2.6 Ma, and it is still active today, as indicated by the ruptured seabed. High-resolution bathymetric data reveal shore-parallel seabed steps reaching heights of a few tens of meters. Considering that since the beginning of faulting the average sedimentation rate (100-400 m/My) exceeds the displacement rate (50-100 m/My), the presence of numerous unburied fault scarps indicates seismic ruptures rather than slow creep. For example, considering recent sedimentation rates as measured in seabed cores (5 cm/ka = 50 m/My), if an earthquake produces a 5-m-high fault scarp, it would take about 100 ky to bury it. These preliminary considerations highlight the importance of hazard assessment for seabed infrastructures.</p><p>The recent development of gas fields offshore Israel, as well as the increasing number of planned infrastructures on the seafloor requires a risk assessment, geohazard management, and particularly accurate mapping of faults. Unlike onshore geohazard management, there is no statutory fault map for offshore Israel. Moreover, 'active' and 'potentially active' faults in the offshore area are still not defined. The purpose of this study is to prepare a fault map and discuss criteria for defining the level of fault activity in the marine environment. To accomplish this goal, we use high-resolution bathymetric data and 3D seismic surveys, allowing 3D mapping of faults much better than usually possible onshore.</p><p>For bathymetry, we developed an algorithm, which automatically calculates the height of fault scars along predefined segments. Results indicate higher faults scarps in the north, consistent with extension measurement and steepness of the continental slope that also increases northward. A 3D mapping of fault planes shows that (1) many small faults at the seabed are actually segments of a major fault. This allows reducing the total number of faults to a few large ones. (2) A significant fault can be hidden below the surface with no bathymetric expression. (3) The structure of a seismic reflector dated to 350 ka emphasizes areas with greater recent activity much better than the best available bathymetric data. This allows a quick way to focus on hazardous areas. The next stage of the research will be to measure the area of fault planes and calculate potential earthquake magnitudes. Altogether, we point out the advantage of 3D seismic mapping for geohazard assessment.</p>

EVOLUTION AND MORPHOLOGY OF RAFTED BLOCKS IN AN ANCIENT DEEPWATER MASS TRANSPORT COMPLEX (EXMOUTH PLATEAU, OFFSHORE NW AUSTRALIA)

2020 ◽  
pp. 1-67 ◽  
Author(s):  
Ovie Emmanuel Eruteya ◽  
Yakufu Niyazi ◽  
Kamaldeen Olakunle Omosanya ◽  
Daniel Ierodiaconou ◽  
Andrea Moscariello
Keyword(s):  
Mass Transport ◽  
Deep Water ◽  
High Amplitude ◽  
3D Seismic ◽  
Complex Flow ◽  
Seismic Reflection Data ◽  
Exmouth Plateau ◽  
Reflection Data ◽  
Transport Complex ◽  
Nw Australia

Submarine mass wasting plays a fundamental role in transporting substantial volumes of sediments basinward including gigantic slide blocks. However, the understanding of processes involved in block generation and their associated deformation until flow arrest remains limited, especially in data-starved deep-water settings. Here a 2D and 3D seismic reflection data from the Exmouth Plateau, offshore NW Australia is used to investigate the architecture of large blocks preserved within an ancient mass transport complex (MTC) and their interaction with the basal shear surface (BSS). The evolution of the investigated MTC (MTC-BDF) is related to instability along the flanks of an underlying bifurcative Miocene canyon. MTC-BDF spans ∼75 km by ∼35 km containing at least 32 well-imaged blocks (within the 3D seismic coverage) encapsulated in a well-deformed debrite background. These carbonate blocks interpreted as rafted blocks have lengths ranging from 0.48 km to 3.40 km with thicknesses reaching up to 165 m. Interestingly, the blocks are more abundant in a region characterized by moderate-high amplitude debrites. Erosional morphologies encompassing a unique groove and other circular to irregular-shaped depressions mapped along the BSS provide evidence for the erosive nature of the flow. The origin of the groove is related transported blocks gouging the BSS. Importantly, intra block deformations recorded within these blocks as fault and fold systems suggest a complex flow regime within MTC-BDF, with the deformations arising either during block translation or also possibly upon the arrest of the failed mass in interaction with bathymetric elements. Our findings suggest inherent deformations within these blocks may serve as high-permeability conduits with implications for deep-water drilling operations within this segment of the Exmouth Plateau and elsewhere in other hydrocarbon-rich deep-water settings.

3D Seismic classification of Fluid Escape Pipes in the western Exmouth Plateau, North West Shelf of Australia (A)

2020 ◽  
pp. jgs2020-096
Author(s):  
Susy Mercado Ruge ◽  
Nicola Scarselli ◽  
Awad Bilal
Keyword(s):  
Fluid Flow ◽  
Significant Risk ◽  
Sedimentary Basins ◽  
Upper Jurassic ◽  
Seismic Survey ◽  
3D Seismic ◽  
Seismic Reflection Data ◽  
North West ◽  
Exmouth Plateau ◽  
Northern Carnarvon Basin

Fluid escape pipes are vertical pathways of focused flow venting from a variety of deep overpressure sources. These geological features are typical of many sedimentary basins, including proven petroliferous provinces worldwide, such as the North Sea and the Exmouth Plateau in the Northern Carnarvon Basin, Northwest Australia. High quality three-dimensional (3D) seismic reflection data from the western Exmouth Plateau revealed the occurrence of exceptionally well-imaged fluid escape pipes affecting the Jurassic strata and the Triassic Mungaroo Formation, a key reservoir unit in the basin. A total of 171 fluid escape pipes, including blowout, seepage and hydrothermal pipes, were mapped, and their geomorphic characteristics were analysed. In the study area, these features form prominent vertical columns up to 4.5 km long disrupting continuous reflections of the Triassic to Jurassic section. Numerous fluid escape pipes terminate with paleo-pockmarks affecting at the Upper Jurassic syn-extension strata, providing evidence for pipe genesis during the early stages of the Late Jurassic rifting in the Exmouth Plateau . Fluid escape pipes were found rooting from different stratigraphic levels, suggesting multiple fluid sources within the Triassic sediments. Several fluid flow structures nucleated along or nearby rift-related fault planes within the Mungaroo Formation providing further evidence of rifting as a main triggering factor of important fluid flow in the basin.In the study area, the presence of fluid escape pipes represents a significant risk for the preservation of potential hydrocarbons accumulations as when these features form, vertical fluid venting breaches through stratigraphy compromising the integrity of seal units. This seems supported by the lack of significant discoveries within the area covered by seismic survey analysed in this research.

High Resolution Microscopy of Multi-Layered Biological Crystals

1982 ◽  
Vol 40 ◽  
pp. 80-83
Author(s):  
H.A. Cohen ◽  
T.W. Jeng ◽  
W. Chiu
Keyword(s):  
High Resolution ◽  
Low Dose ◽  
Three Dimensional ◽  
Data Interpretation ◽  
Two Dimensional ◽  
Biological Objects ◽  
Density Maps ◽  
Density Map ◽  
Complex Crystal ◽  
High Resolution Microscopy

This tutorial will discuss the methodology of low dose electron diffraction and imaging of crystalline biological objects, the problems of data interpretation for two-dimensional projected density maps of glucose embedded protein crystals, the factors to be considered in combining tilt data from three-dimensional crystals, and finally, the prospects of achieving a high resolution three-dimensional density map of a biological crystal. This methodology will be illustrated using two proteins under investigation in our laboratory, the T4 DNA helix destabilizing protein gp32*I and the crotoxin complex crystal.

scholarly journals Geomorphological Geometries and High-Resolution Seismic Sequence Stratigraphy of Malay Basin’s Fluvial Succession

2021 ◽  
Vol 11 (11) ◽  
pp. 5156
Author(s):  
Abd Al-Salam Al-Masgari ◽  
Mohamed Elsaadany ◽  
Numair A. Siddiqui ◽  
Abdul Halim Abdul Latiff ◽  
Azli Abu Bakar ◽  
...  
Keyword(s):  
High Resolution ◽  
Sequence Stratigraphy ◽  
Three Dimensional ◽  
Seismic Attributes ◽  
Seismic Facies ◽  
Seismic Sequence ◽  
3D Seismic ◽  
Seismic Sequences ◽  
Seismic Sequence Stratigraphy ◽  
Point Bars

This study identified the Pleistocene depositional succession of the group (A) (marine, estuarine, and fluvial depositional systems) of the Melor and Inas fields in the central Malay Basin from the seafloor to approximately −507 ms (522 m). During the last few years, hydrocarbon exploration in Malay Basin has moved to focus on stratigraphic traps, specifically those that existed with channel sands. These traps motivate carrying out this research to image and locate these kinds of traps. It can be difficult to determine if closely spaced-out channels and channel belts exist within several seismic sequences in map-view with proper seismic sequence geomorphic elements and stratigraphic surfaces seismic cross lines, or probably reinforce the auto-cyclic aggregational stacking of the avulsing rivers precisely. This analysis overcomes this challenge by combining well-log with three-dimensional (3D) seismic data to resolve the deposition stratigraphic discontinuities’ considerable resolution. Three-dimensional (3D) seismic volume and high-resolution two-dimensional (2D) seismic sections with several wells were utilized. A high-resolution seismic sequence stratigraphy framework of three main seismic sequences (3rd order), four Parasequences sets (4th order), and seven Parasequences (5th order) have been established. The time slice images at consecutive two-way times display single meandering channels ranging in width from 170 to 900 m. Moreover, other geomorphological elements have been perfectly imaged, elements such as interfluves, incised valleys, chute cutoff, point bars, and extinction surfaces, providing proof of rapid growth and transformation of deposits. The high-resolution 2D sections with Cosine of Phase seismic attributes have facilitated identifying the reflection terminations against the stratigraphic amplitude. Several continuous and discontinuous channels, fluvial point bars, and marine sediments through the sequence stratigraphic framework have been addressed. The whole series reveals that almost all fluvial systems lay in the valleys at each depositional sequence’s bottom bars. The degradational stacking patterns are characterized by the fluvial channels with no evidence of fluvial aggradation. Moreover, the aggradation stage is restricted to marine sedimentation incursions. The 3D description of these deposits permits distinguishing seismic facies of the abandoned mud channel and the sand point bar deposits. The continuous meandering channel, which is filled by muddy deposits, may function as horizontal muddy barriers or baffles that might isolate the reservoir body into separate storage containers. The 3rd, 4th, and 5th orders of the seismic sequences were established for the studied succession. The essential geomorphological elements have been imaged utilizing several seismic attributes.

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