Synsedimentary collapse of portions of the lower Blomidon Formation (Late Triassic), Fundy rift basin, Nova Scotia

1995 ◽  
Vol 32 (11) ◽  
pp. 1965-1976 ◽  
Author(s):  
Rolf V. Ackermann ◽  
Roy W. Schlische ◽  
Paul E. Olsen
Keyword(s):  
Nova Scotia ◽  
Late Triassic ◽  
Normal Faults ◽  
Rift Basin ◽  
Rift Basins ◽  
Kink Bands ◽  
Deformation Features ◽  
Terrestrial Environments ◽  
Sediment Deformation ◽  
Fluvial Sandstone

A chaotic mudstone unit within the lower Blomidon Formation (Late Triassic) has been traced for 35 km in the Mesozoic Fundy rift basin of Nova Scotia. This unit is characterized by highly disrupted bedding that is commonly cut by small (<0.5 m) domino-style synsedimentary normal faults, downward movement of material, geopetal structures, variable thickness, and an irregular, partially faulted contact with the overlying unit. The chaotic unit is locally overlain by a fluvial sandstone, which is overlain conformably by mudstone. Although the thickness of the sandstone is highly variable, the overlying mudstone unit exhibits only gentle regional dip. The sandstone unit exhibits numerous soft-sediment deformation features, including dewatering structures, convoluted bedding, kink bands, and convergent fault fans. The frequency and intensity of these features increase dramatically above low points at the base of the sandstone unit. These stratigraphic relations suggest buried interstratal karst, the subsurface dissolution of evaporites bounded by insoluble sediments. We infer that the chaotic unit was formed by subsidence and collapse resulting from the dissolution of an evaporite bed or evaporite-rich unit by groundwater, producing dewatering and synsedimentary deformation structures in the overlying sandstone unit, which infilled surface depressions resulting from collapse. In coeval Moroccan rift basins, facies similar to the Blomidon Formation are associated with halite and gypsum beds. The regional extent of the chaotic unit indicates a marked period of desiccation of a playa lake of the appropriate water chemistry. The sedimentary features described here may be useful for inferring the former existence of evaporites or evaporite-rich units in predominantly clastic terrestrial environments.

Regional Seal as Key Controlled Elements of Petroleum Accumulation in the Rift Basin

2012 ◽  
Vol 524-527 ◽  
pp. 190-193
Author(s):  
Hai Yan Hu ◽  
Zhe Zhao ◽  
Song Lu ◽  
Hang Zhou Xiao
Keyword(s):  
Source Rock ◽  
Oil And Gas ◽  
Thickness Distribution ◽  
Normal Faults ◽  
Hydrocarbon Generation ◽  
Geological Condition ◽  
Rift Basin ◽  
Rift Basins ◽  
Northwest Germany ◽  
Petroleum Accumulation

Rift basin is an important petroleum basin type, in which about one third of oil and gas was discovered. To research on the main controlled elements of oil and gas accumulation, five typical rift basins in Europe are focused on the geological condition such as source rock, reservoir, seal, petroleum system, and accumulation with logging, hole, measured and analytical methods, and so on. The results showed the main regional seal controlled the petroleum distribution in the rift basin. Seals are defined by main regional seal, minor regional seas and local region according to thickness, distribution, lithostratigraphy. Viking Graben of North Sea has main regional seal about 3000m thick during late Jurassic and Cretaceous, about 81 percent of petroleum is in the Jurassic reservoir; Anglo-Dutch basin has main region thick seal during Triassic through Jurassic, and Permian reservoir accounted for 73 percent of basin reserves; Voring Basin has the main regional seal during Cretaceous through early Tertiary, the Jurassic reservoir has 85 percent of whole basin reserves; Northeast and Northwest Germany Basins have the evaporites as main regional seals during late Permian, and Permian reservoir accounted for more than 80 percent of basin reservoir, respectively. Rift Basin can develop reservoir like turbidite, source rock, seal in the basin dynamic opinion. Some main regional seals may develop overpressre because of quick subside and hydrocarbon generation at some conditions, it can strengthen seal capability. Oil and gas can migration to the main regional seal by normal faults caused by rifting, which can stop further migration so that they were accumulated under the main regional seal.

Mesozoic rift onset and its impact on the sequence stratigraphic architecture of the Northern Carnarvon Basin

2016 ◽  
Vol 56 (1) ◽  
pp. 143 ◽  
Author(s):  
Anthony Gartrell ◽  
Jose Torres ◽  
Matt Dixon ◽  
Myra Keep
Keyword(s):  
Marked Change ◽  
Middle Part ◽  
Late Triassic ◽  
Normal Faults ◽  
Rift Basins ◽  
Tectonic Event ◽  
Growth Strata ◽  
Stratigraphic Architecture ◽  
Northern Carnarvon Basin ◽  
Carnarvon Basin

Ages varying from Late Triassic to Early Jurassic have been proposed by different authors for the onset of rifting in the Northern Carnarvon Basin. Seismic sections from the Exmouth Sub-basin and outer Exmouth Plateau demonstrate significant growth strata associated with displacement on normal faults starting at least at the base of the R. rhaetica zone (Rhaetian). This tectonic event coincides with a marked change in sequence architecture and a large landward shift (~300 km) of the paleo-shoreline to the vicinity of the Rankin and Alpha Arch trends. Rapid creation of accommodation in the inboard narrow rift basins (Exmouth, Barrow and Dampier sub-basins) is suggested to be the most likely cause of this major transgression. The preferential development of associated carbonate build-ups during the Rhaetian on the footwall side of active tilted fault blocks provides additional evidence for the onset of significant extensional faulting occurring during this time. An earlier more subtle initiation phase of rifting, however, is interpreted during the Norian, from around the middle part of the H. balmei biozone time, above which a change in stratigraphic architecture from aggrading to retrograding occurs. The observed structural and stratigraphic transitions can be related to typical phases of evolution described in many rift basins around the world. The work highlights the importance of integrating regional structural geology, sequence stratigraphy and depositional systems observations to provide robust constraints for basin evolutions.

Neotectonic evolution of the Brazilian northeastern continental margin based on sedimentary facies and ichnology,

2014 ◽  
Vol 82 (2) ◽  
pp. 462-472 ◽  
Author(s):  
Rosana Gandini ◽  
Dilce de Fátima Rossetti ◽  
Renata Guimarães Netto ◽  
Francisco Hilário Rego Bezerra ◽  
Ana Maria Góes
Keyword(s):  
Sea Level ◽  
Continental Margin ◽  
Sedimentary Facies ◽  
Passive Margin ◽  
South American ◽  
Soft Sediment ◽  
Rift Basins ◽  
Deformation Structures ◽  
Last Glaciation ◽  
Sediment Deformation

AbstractQuaternary post-Barreiras sediments are widespread along Brazil's passive margin. These deposits are well exposed in the onshore Paraíba Basin, which is one of the rift basins formed during the Pangean continental breakup. In this area, the post-Barreiras sediments consist of sandstones with abundant soft-sediment deformation structures related to seismicity contemporaneous with deposition. The trace fossilsThalassinoidesandPsilonichnusare found up to 38 m above modern sea level in sandstones dated between 60.0 (± 1.4) and 15.1 (± 1.8) ka. The integration of ichnological and sedimentary facies suggests nearshore paleoenvironments. Such deposits could not be related to eustatic sea-level rise, as this time coincides with the last glaciation. Hence, an uplift of 0.63 mm/yr, or 1.97 mm/yr if sea level was 80 m lower in the last glaciation, would have been required to ascend the post-Barreiras sediments several meters above the present-day sea level during the last 60 ka. This would suggest that the post-rift stage of the South American eastern passive margin may have experienced tectonic reactivation more intense than generally recognized. Although more complete data are still needed, the information presented herein may play an important role in studies aiming to decipher the Quaternary evolution of this passive margin.

scholarly journals The “Passive” Margin of Eastern North America: Rifting and the Influence of Prerift Orogenic Activity on Postrift Development

Lithosphere ◽  
2020 ◽  
Vol 2020 (1) ◽  
pp. 1-29
Author(s):  
Martha Withjack ◽  
MaryAnn Malinconico ◽  
Michael Durcanin
Keyword(s):  
Passive Margin ◽  
Rift System ◽  
Rift Basin ◽  
Rift Basins ◽  
Isostatic Rebound ◽  
Left Behind ◽  
Crustal Thinning ◽  
Hinge Zone ◽  
Uplift And Erosion ◽  
Ocean Boundary

Abstract We have analyzed and synthesized geologic and geophysical data from the onshore Newark rift basin and adjacent onshore and offshore basins to better understand the Mesozoic development of the eastern North American rift system and passive margin. Our work indicates that rifting had three phases: (1) an initial, prolonged phase of extension and subsidence; (2) a short-lived phase with higher rates of extension and subsidence, intrabasin faulting, and intense magmatism; and (3) a final phase with limited subsidence and deposition. Additionally, our work shows that anomalous uplift and erosion, associated with crustal-scale arching/warping subparallel to the prerift and syn-rift crustal fabric not the continent-ocean boundary, affected a region landward of the basement hinge zone. Uplift and erosion began during the final rifting phase and continued into early drifting with erosion locally exceeding 6 km. Subsequent subsidence was minimal. We propose that denudation unloading related to relic, prerift orogenic crustal thickness and elevated topography triggered the anomalous uplift and erosion. After the Paleozoic orogenies, postorogenic denudation unloading (cyclic erosion and isostatic rebound/uplift) significantly thinned the thickened crust and reduced topographic elevation. During rifting, extension stretched and tectonically thinned the crust, promoting widespread subsidence and deposition that dampened the postorogenic cycle of erosion and isostatic rebound/uplift. During the rift-drift transition, with extension focused near the breakup site, denudation unloading resumed landward of the basement hinge zone, producing significant erosion and uplift (related to isostatic rebound), crustal thinning, and topographic decay that left behind only eroded remnants of the once massive rift basins.

Paleomagnetism of the Late Triassic, North Mountain Basalt of Nova Scotia

1968 ◽  
Vol 73 (8) ◽  
pp. 2811-2822 ◽  
Author(s):  
C. M. Carmichael ◽  
H. C. Palmer
Keyword(s):  
Nova Scotia ◽  
Late Triassic

scholarly journals Extensional Messinian basins in the Central Mediterranean (Calabria, Italy): new stratigraphic and tectonic insights

2018 ◽  
Vol 73 ◽  
pp. 45 ◽  
Author(s):  
Alfonsa Milia ◽  
Maurizio M. Torrente
Keyword(s):  
Water Environment ◽  
Sedimentary Basins ◽  
Normal Faults ◽  
Seismic Profiles ◽  
Rift Basins ◽  
Central Mediterranean ◽  
Tectonic Events ◽  
Basin Subsidence ◽  
Basement Deformation ◽  
Two Stages

The direction of extension and the architecture of the Messinian basins of the Central Mediterranean region is a controversial issue. By combining original stratigraphic analysis of wells and seismic profiles collected offshore and onshore Calabria, we reassess the tectonic evolution that controlled the sedimentation and basement deformation during Messinian times. Three main deep sedimentary basins in the Calabria area record a Messinian succession formed by two clays/shales-dominated subunits subdivided by a halite-dominated subunit. The correlation with the worldwide recognized stratigraphic features permit to define the chronology of the stratigraphic and tectonic events. Three main rift basins that opened in a N-S direction have been recognized. On the contrary a fourth supradetachment basin opened toward the East. We found that the basin subsidence was controlled by two stages of activity of normal faults and that Messinian rift basins evolve in a deep-water environment. The overall pattern of extensional faults of the Central Mediterranean corresponds to normal faults striking parallel to the trench and normal faults striking at an oblique angle to the trench (Fig. 14). In particular in Campania and Calabria regions are present two rifts parallel to trench and an intervening rift orthogonal to the trench. We maintain that the recognized Messinian rift basins can be interpreted according to the “Double-door saloon tectonics”.

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