Outcrop and Seismic Examples of Mass-Transport Deposits from a Late Miocene Deep-Water Succession, Taranaki Basin, New Zealand

The Brazilian Continental Margin (BEM) deep-water regions contain important geological features that need advance in their characterization. Mass-transport deposits (MTD) are important not only by their significance in the sedimentary but also because of their negative impact economically. A slump is a coherent mass of sediment that moves on a concave-up glide plane and undergoes rotational movements causing internal deformation and one of the basic types of MTD. The study area comprises part of the offshore Potiguar Basin in NE Brazil, on the distal eastern portion of the Touros High and Fernando de Noronha Ridge. This portion of the Potiguar Basin comprises a transform rift system that has evolved into a continental passive margin. This basin represents an important location related to the breakup between South America and Africa. The database used in this work included 2D post-stack time-migrated seismic profiles from the Brazilian Agency of Petroleum, Natural Gas, and Biofuels (ANP). The slumps reflectors are identified on the continental shelf profiles in form of present clinoform configuration, medium to high continuity, high amplitudes, and medium to high frequencies, representing a sigmoidal oblique complex prograding reflector. The slump scars at the continental slope indicate that this is a gravitationally unstable area that will eventually collapse, resulting in erosional features on the continental slope and deposition on the continental rise. Our results provide some insights regarding MDT slumps sedimentary evolution in the BEM deep water area as well as their interrelation with other sedimentary deposits.

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Influence of mass transport deposit (MTD) surface topography on deep-water deposition: an example from a predominantly fine-grained continental margin, New Zealand

Geological Society London Special Publications ◽

10.1144/sp500-2019-192 ◽

2020 ◽

Vol 500 (1) ◽

pp. 147-171 ◽

Cited By ~ 2

Author(s):

Suzanne Bull ◽

Greg H. Browne ◽

Malcolm J. Arnot ◽

Lorna J. Strachan

Keyword(s):

New Zealand ◽

Mass Transport ◽

Surface Topography ◽

Deep Water ◽

Three Dimensional ◽

Sediment Supply ◽

Fine Grained ◽

Basin Floor ◽

Detachment Surface ◽

Image Part

AbstractThree-dimensional (3D) seismic data reveal the complex interplay between the surface topography of a c. 4405 km3 mass transport deposit (MTD) and overlying sedimentary packages over approximately the last two million years. The data image part of the Pleistocene to recent shelf to slope to basin-floor Giant Foresets Formation in offshore western New Zealand. The MTD created substantive topographic relief and rugosity at the contemporaneous seabed, formed by the presence of a shallow basal detachment surface, and very large (up to 200 m high) intact slide blocks, respectively. Sediments were initially deflected away from high-relief MTD topography and confined in low areas. With time, the MTD was progressively healed by a series of broadly offset-stacked and increasingly unconfined packages comprised of many channel bodies and their distributary complexes. Positive topography formed by the channels and their distributary complexes further modified the seafloor and influenced the location of subsequent sediment deposition. Channel sinuosity increased over time, interpreted as the result of topographic healing and reduced seafloor gradients. The rate of sediment supply is likely to have been non-uniform, reflecting tectonic pulses across the region. Sediments were routed into deep water via slope-confined channels that originated shortly before emplacement of the MTD.

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Syndepositional tectonics and mass-transport deposits control channelized, bathymetrically complex deep-water systems (Aínsa depocenter, Spain)

Journal of Sedimentary Research ◽

10.2110/jsr.2020.38 ◽

2020 ◽

Vol 90 (7) ◽

pp. 729-762

Author(s):

Daniel E. Tek ◽

Miquel Poyatos-Moré ◽

Marco Patacci ◽

Adam D. McArthur ◽

Luca Colombera ◽

...

Keyword(s):

Mass Transport ◽

Deep Water ◽

Tectonic Setting ◽

Water Systems ◽

Tectonic Structures ◽

Lateral Confinement ◽

Facies Associations ◽

Active Tectonic ◽

Basin Floor ◽

Mass Transport Deposits

ABSTRACT The inception and evolution of channels in deep-water systems is controlled by the axial gradient and lateral confinement experienced by their formative flows. These parameters are often shaped by the action of tectonic structures and/or the emplacement of mass-transport deposits (MTDs). The Arro turbidite system (Aínsa depocenter, Spanish Pyrenees) is an ancient example of a deep-water channelized system from a bathymetrically complex basin, deposited in an active tectonic setting. Sedimentologic fieldwork and geologic mapping of the Arro system has been undertaken to provide context for a detailed study of three of the best-exposed outcrops: Sierra de Soto Gully, Barranco de la Caxigosa, and Muro de Bellos. These locations exemplify the role of confinement in controlling the facies and architecture in the system. Sedimentologic characterization of the deposits has allowed the identification of fifteen facies and eight facies associations; these form a continuum and are non-unique to any depositional environment. However, architectural characterization allowed the grouping of facies associations into four depositional elements: i) weakly confined, increasing-to-decreasing energy deposits; ii) progradational, weakly confined to overbank deposits; iii) alternations of MTDs and turbidites; iv) channel fills. Different styles of channel architecture are observed. In Barranco de la Caxigosa, a master surface which was cut and subsequently filled hosts three channel stories with erosional bases; channelization was enhanced by quasi-instantaneous imposition of lateral confinement by the emplacement of MTDs. In Muro de Bellos, the inception of partially levee-confined channel stories was enhanced by progressive narrowing of the depositional fairway by tectonic structures, which also controlled their migration. Results of this study suggest that deep-water channelization in active tectonic settings may be enhanced or hindered due to: 1) flow interaction with MTD-margin topography or; 2) MTD-top topography; 3) differential compaction of MTDs and/or sediment being loaded into MTDs; 4) formation of megascours by erosive MTDs; 5) basin-floor topography being reset by MTDs. Therefore, the Arro system can be used as an analog for ancient subsurface or outcrop of channelized deposits in bathymetrically complex basins, or as an ancient record of deposits left by flow types observed in modern confined systems.

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Evolution of a Late Miocene Deep-water Depositional System in the Southern Taranaki Basin, New Zealand

10.20944/preprints202105.0300.v1 ◽

2021 ◽

Author(s):

Clayton Silver ◽

Heather Bedle

Keyword(s):

New Zealand ◽

Deep Water ◽

Late Miocene ◽

Water Channel ◽

Three Dimensional ◽

Depositional Environments ◽

Architectural Elements ◽

Shelf Slope ◽

Spatio Temporal ◽

Channel Systems

A long-standing problem in the understanding of deep-water turbidite reservoirs relates to how the three-dimensional evolution of deep-water channel systems evolve in response to channel filling on spatio-temporal scales, and how depositional environments affect channel architecture. The 3-D structure and temporal evolution of late Miocene deep-water channel complexes in the southern Taranaki Basin, New Zealand is investigated, and the geometry, distribution and stacking patterns of the channel complexes are analyzed. Two recently acquired 3-D seismic datasets, the Pipeline-3D (proximal) and Hector-3D (distal) are analyzed. These surveys provide detailed imaging of late Miocene deep-water channel systems, allowing for the assessment of the intricate geometry and seismic geomorphology of the systems. Seismic attributes resolve the channel bodies and the associated architectural elements. Spectral decomposition, amplitude curvature, and coherence attributes reveal NW-trending straight to low-sinuosity channels and less prominent NE-trending high-sinuosity feeder channels. Stratal slices across the seismic datasets better characterize the architectural elements. The mapped turbidite systems transition from low-sinuosity to meandering high-sinuosity patterns, likely caused by a change in the shelf-slope gradient due to localized structural relief. Stacking facies patterns within the channel systems reveal the temporal variation from a depositional environment characterized by sediment bypass to vertically aggrading channel systems.

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Tectonic and geomorphic controls on the distribution of submarine landslides across active and passive margins, eastern New Zealand

10.5194/egusphere-egu2020-3194 ◽

2020 ◽

Author(s):

Sally Watson ◽

Joshu Mountjoy ◽

Gareth Crutchley

Keyword(s):

New Zealand ◽

Mass Transport ◽

Submarine Landslide ◽

Sediment Supply ◽

Submarine Landslides ◽

Mass Wasting ◽

Active Margin ◽

Eastern Margin ◽

Marine Habitats ◽

Mass Transport Deposits

Submarine landslides occur on continental margins globally and can have devastating consequences for marine habitats, offshore infrastructure and coastal communities due to potential tsunamigenic consequences. Evaluation of the magnitude and distribution of submarine landslides is central to marine and coastal hazard planning. Despite this, there are few studies that comprehensively quantify the occurrence of submarine landslides on a margin-wide scale.&#160;We present the first margin-wide submarine landslide database along the eastern margin of New Zealand comprising >2200 landslide scars and associated mass-transport deposits. Analysis of submarine landslide distribution reveals 1) locations prone to mass-failure, 2) spatial patterns of landslide scale and occurrence, and 3) the potential preconditioning factors and triggers of mass wasting across different geologic settings.&#160;Submarine landslides are widespread on the eastern margin of New Zealand, occurring in water depths from ~300 m to ~4,000 m. Landslide scars and mass transport deposits are more prevalent, and on average larger, on the active margin, compared the passive margin. We attribute higher concentrations of landslides on the active margin to the prevalence of deforming thrust ridges, related to active margin processes including oversteepening, faulting and seamount subduction. Higher sediment supply on the northernmost active margin is also likely to be a key preconditioning factor resulting in the concentration of large landslides in this region.&#160;In general, submarine landslide scars are concentrated around canyon systems and close to canyon thalwegs. This suggests that not only does mass wasting play a major role in canyon evolution, but also that slope undercutting in canyons may be a fundamental preconditioning factor for slope failure.&#160;Results of this study offer unique insights into the spatial distribution, magnitude and morphology of submarine landslides across different geologic settings, providing a better understanding of the causative factors for mass wasting in New Zealand and around the world.&#160;

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Overbank sediment waves in the Southern Taranaki Basin, New Zealand

Interpretation ◽

10.1190/int-2020-0011.1 ◽

2020 ◽

pp. 1-13

Author(s):

Clayton Silver ◽

Heather Bedle

Keyword(s):

New Zealand ◽

Cross Section ◽

Deep Water ◽

Late Miocene ◽

Seismic Data ◽

Water Channel ◽

Sediment Waves ◽

Continuous Record ◽

Study Interval ◽

Channel Systems

Modern 3-D seismic data in the southern Taranaki Basin reveals a continuous record of deep-water channel systems initiating in the late Miocene. Investigation of a selected interval of the Mount Messenger Formation channel systems reveals shingled, down-lapping reflectors when viewed in cross section. Volume attributes were generated and subsequently extracted upon interpreted surfaces and stratal slices through the study interval to characterize the interesting features in the seismic data. Combining attribute and seismic geomorphologic interpretations indicates that these features are likely scarps related to overbank sediment waves.

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