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3. ‘Block and basin’ style rift basins: sedimentological insights from the Mississippian Fell Sandstone Formation

Author

Howell, Louis P., Priddy, Charlotte, Mitten, Andrew J., Jeffery, Adam J., Egan, Stuart S., Leslie, Graham, Pettigrew, Ross P., Clarke, Stuart M., Kearsey, Timothy I., Howell, Louis P., Priddy, Charlotte, Mitten, Andrew J., Jeffery, Adam J., Egan, Stuart S., Leslie, Graham, Pettigrew, Ross P., Clarke, Stuart M., and Kearsey, Timothy I.

Abstract

The block and basin tectonostratigraphic framework for the northern Pennine (rift) Basin, within which buoyant granite intrusions core intra-basin fault-bounded blocks, has long held traction. However, many of the elements of this framework are rooted in primitive tectonic models and, perhaps unsurprisingly, corresponding depositional models often reflect this. Using sedimentological and sedimentary provenance approaches, the synrift (Mississippian) fluvio-deltaic Fell Sandstone Formation and age-equivalent strata within the northern Pennine Basin are examined. Highlighted divergences from classically depicted models relate to occurrences of pre-Carboniferous basement domes or monoclines, which are unbounded by major vertically displacing (>100 m) fault systems. Such structures in the northern Pennine Basin are all granite-cored and their origins are associated with their buoyancy and flexural isostatic processes. One such basement dome, the Cheviot Block, confined and deflected the Fell Sandstone fluvio-deltaic system from the west, causing locally elevated net sand content and variations in the dominant palaeodrainage direction. Central parts of the Alston Block, which forms a regional monocline along an east–west axis, were comparatively uplifted because of flexural isostatic responses to granite intrusions. The findings presented are at variance not only with classically depicted depositional models for the region, but also with more general depictions of dominantly normal fault-driven rift basin systems.

Published
2022

7. Supplementary data table 3. ���Block and basin��� style rift basins: sedimentological insights from the Mississippian Fell Sandstone Formation

Author

Howell, Louis P., Priddy, Charlotte, Mitten, Andrew J., Jeffery, Adam J., Egan, Stuart S., Leslie, Graham, Pettigrew, Ross P., Clarke, Stuart M., and Kearsey, Timothy I.

Abstract

Supplementary data table 3: Concentrations of selected element oxides in weight per cent (wt. %) for sandstone samples belonging to the Fell Sandstone Formation across the northern Pennine Basin. Bdl, below limit of detection.

Published
2021
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8. Supplementary data table 2. ���Block and basin��� style rift basins: sedimentological insights from the Mississippian Fell Sandstone Formation

Author

Howell, Louis P., Priddy, Charlotte, Mitten, Andrew J., Jeffery, Adam J., Egan, Stuart S., Leslie, Graham, Pettigrew, Ross P., Clarke, Stuart M., and Kearsey, Timothy I.

Abstract

Supplementary data table 2: Concentrations of selected elements in parts per million (ppm) for sandstone samples belonging to the Fell Sandstone Formation across the northern Pennine Basin. Bdl, below limit of detection.

Published
2021
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10. Rheological, thermal and isostatic constraints on continental lithosphere extension and compression

Author

Egan, Stuart S. and Kusznir, Nick

Subjects
551.21, QE Geology
Abstract

Deep seismic reflection data has shown the importance of low angle faults and detachments in continental extensional tectonics. A quantitative model of continental lithosphere extension is presented, incorporating geometric, thermal and isostatic components. The upper lithosphere extends by simple shear associated with low angle faults, while the lower lithosphere deforms by pure shear. The resulting sedimentary basin geometry and crustal structure are dependent upon the amount of lithosphere extension, the distribution of the pure shear, the depth of the horizontal detachment, the geometry of the low angle fault and the isostatic response of the lithosphere during rifting and thermal subsidence. The Jeanne d' Arc basin, Newfoundland is most closely represented by models incorporating the flexural isostatic response of the lithosphere to applied loading. Stratigraphic data shows that the basin was generated by several pulses of extension and rifting was followed by erosion. Modelling techniques are used to assess the implications of these phenomena. A two dimensional study of the rheological strength of the lithosphere shows it to be determined by the interaction between the pre-rift thermal state of the lithosphere, the position of simple shear deformation with respect to that of pure shear, time since rifting and the rate of extension. Model predictions of lithosphere shortening on low angle thrusts have been combined with the extensional modelling technique to explore the process of basin inversion. Model predictions are compared with observations from the North Celtic Sea Basin. Extension on planar faults is modelled by considering the footwall and hanging wall as two interacting cantilevers, which flex in response to the isostatic forces created during extension. The construction has been applied to extension on a sequence of planar faults and predicts the familiar "domino-style" block rotation.

Published
1988

11. Tracking Sustainability Concepts in Geology and Earth Science Teaching and Learning, Keele University, UK

Author

Rogers, Steven L., Egan, Stuart S., and Stimpson, Ian G.

Subjects
QE
Abstract

Sustainability of the planet is fundamental to our common future, and geologists and geoscientists are key stakeholders in this process. Better understanding of the Earth, its processes and utilisation of its resources, through successful science communication, is necessary for the effective creation of sustainability policy. Whilst the synergy between geoscience and sustainability is often obvious, the framing of the links is often neglected or downplayed within the UK Higher Education setting. This results in geoscientists lacking in familiarity with sustainability issues, including the ability to communicate geoscience issues to non-specialists effectively. Using the United Nations Sustainable Development Goals, the inclusion and embedding of sustainability issues within Geology and Geoscience modules (offered by the School of Geography, Geology and the Environment, Keele University, UK) is framed in an effort to consolidate and enhance our current standing on sustainability issues. Further tracking of the emphasis and positioning of sustainability issues within these modules will enable a better articulation of the importance between geology and society.

Published
2018

13. Subsidence and uplift mechanisms within the South Caspian Basin: insights from the onshore and offshore Azerbaijan region

Author

Egan, Stuart S., Mosar, Jon, Brunet, Marie-Françoise, Kangarli, Talat, Egan, Stuart S., Mosar, Jon, Brunet, Marie-Françoise, and Kangarli, Talat

Abstract

A combination of fieldwork, basin analysis and modelling techniques has been used to try and understand the role, as well as the timing, of the subsidence–uplift mechanisms that have affected the Azerbaijan region of the South Caspian Basin (SCB) from Mesozoic to Recent.Key outcrops have been studied in the eastern Greater Caucasus, and the region has been divided into several major tectonic zones that are diagnostic of different former sedimentary realms representing a complete traverse from a passive margin setting to slope and distal basin environments. Subsequent deformation has caused folds and thrusts that generally trend from NW–SE to WNW–ESE.Offshore data has been analysed to provide insights into the regional structural and stratigraphic evolution of the SCB to the east of Azerbaijan. Several structural trends and subsidence patterns have been identified within the study area. In addition, burial history modelling suggests that there are at least three main components of subsidence, including a relatively short-lived basin-wide event at 6 Ma that is characterized by a rapid increase in the rate of subsidence.Numerical modelling that includes structural, thermal, isostatic and surface processes has been applied to the SCB. Models that reconcile the observed amount of fault-controlled deformation with the magnitude of overall thinning of the crust generate a comparable amount of subsidence to that observed in the basin. In addition, model results support the tectonic scenario that SCB crust has a density that is compatible with an oceanic composition and is being under-thrust beneath the central Caspian region.

Published
2009

15. Modeling the tectonic development of the Tucano and Sergipe-Alagoas rift basins, Brazil

Author

Karner, Garry D., Egan, Stuart S., and Weissel, Jeffrey K.

Abstract

The Tucano and Sergipe-Alagoas basins of northeast Brazil form part of a regional extensional basin system that was operative during the Mesozoic breakup of South America and Africa with both basins developing on Precambrian crust. The synchronous development of the rift basins suggest that they are genetically linked in space and time. Whereas the offshore Sergipe-Alagoas basin is characterized by a substantial thickness of post-rift sediment, the Tucano basin either failed to develop or at least preserve a significant thickness of post-rift sediment. Observed primary porosities within both pre- and syn-rift Tucano basin sediment imply that significant post-rift sedimentation never occurred. Failure to develop significant post-rift subsidence has important thermal and mechanical implications for the reaction of the lithosphère to rifting and can be explained in terms of: (1) depth-dependent lithospheric extension in which intracrustal detachments allow the extension of the crust to be decoupled from the thinning of the lithospheric mantle, (2) small rates of extension that allow the lithosphere to cool during rifting, and/or (3) lithospheric rifting during which the flexural strength of the lithosphere remains high. With respect to points (2) and (3), forward modeling demonstrates that finite rifting rates over a 20–25 m.y. period are insufficient to cool the lithosphere to the point where post-rift subsidence fails to develop. An interesting complication arises when the flexural strength of the lithosphere remains large during rifting: it tends to suppress the vertical motions of the lithosphere, such as those engendered by the cooling of the lithosphere following rifting, thereby reducing significantly the amplitude of the post-rift subsidence. Thus, the lack of post-rift sedimentation within a basin does not necessarily imply that extension has been limited to the crust.

Published
1992
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16. Rheological, thermal and isostatic constraints on continental lithosphere extension and compression

Author

Egan, Stuart S and Kusznir, Nick

Subjects
QE
Abstract

Deep seismic reflection data has shown the importance of low angle faults and detachments in continental extensional tectonics. A quantitative model of continental lithosphere extension is presented, incorporating geometric, thermal and isostatic components. The upper lithosphere extends by simple shear associated with low angle faults, while the lower lithosphere deforms by pure shear. \ud The resulting sedimentary basin geometry and crustal structure are dependent upon the amount of lithosphere extension, the distribution of the pure shear, the depth of\ud the horizontal detachment, the geometry of the low angle\ud fault and the isostatic response of the lithosphere during\ud rifting and thermal subsidence.\ud The Jeanne d' Arc basin, Newfoundland is most closely\ud represented by models incorporating the flexural isostatic\ud response of the lithosphere to applied loading.\ud Stratigraphic data shows that the basin was generated by\ud several pulses of extension and rifting was followed by\ud erosion. Modelling techniques are used to assess the\ud implications of these phenomena.\ud A two dimensional study of the rheological strength of the\ud lithosphere shows it to be determined by the interaction\ud between the pre-rift thermal state of the lithosphere, the\ud position of simple shear deformation with respect to that of pure shear, time since rifting and the rate of extension.\ud Model predictions of lithosphere shortening on low angle\ud thrusts have been combined with the extensional modelling\ud technique to explore the process of basin inversion. Model\ud predictions are compared with observations from the North\ud Celtic Sea Basin.\ud Extension on planar faults is modelled by considering the footwall and hanging wall as two interacting cantilevers, which flex in response to the isostatic forces created during extension. The construction has been applied to extension on a sequence of planar faults and predicts the familiar "domino-style" block rotation.

Published
1988

17. Subsidence and uplift mechanisms within the South Caspian Basin: insights from the onshore and offshore Azerbaijan region

Author

Egan, Stuart S., Mosar, Jon, Brunet, Marie-Françoise, Kangarli, Talat, Egan, Stuart S., Mosar, Jon, Brunet, Marie-Françoise, and Kangarli, Talat

Abstract

A combination of fieldwork, basin analysis and modelling techniques has been used to try and understand the role, as well as the timing, of the subsidence–uplift mechanisms that have affected the Azerbaijan region of the South Caspian Basin (SCB) from Mesozoic to Recent.Key outcrops have been studied in the eastern Greater Caucasus, and the region has been divided into several major tectonic zones that are diagnostic of different former sedimentary realms representing a complete traverse from a passive margin setting to slope and distal basin environments. Subsequent deformation has caused folds and thrusts that generally trend from NW–SE to WNW–ESE.Offshore data has been analysed to provide insights into the regional structural and stratigraphic evolution of the SCB to the east of Azerbaijan. Several structural trends and subsidence patterns have been identified within the study area. In addition, burial history modelling suggests that there are at least three main components of subsidence, including a relatively short-lived basin-wide event at 6 Ma that is characterized by a rapid increase in the rate of subsidence.Numerical modelling that includes structural, thermal, isostatic and surface processes has been applied to the SCB. Models that reconcile the observed amount of fault-controlled deformation with the magnitude of overall thinning of the crust generate a comparable amount of subsidence to that observed in the basin. In addition, model results support the tectonic scenario that SCB crust has a density that is compatible with an oceanic composition and is being under-thrust beneath the central Caspian region.

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