Stratigraphy: The Modern Synthesis

Miall, Andrew D.

doi:10.1007/978-3-030-87536-7_7

Cited by 7 publications

(5 citation statements)

References 200 publications

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“…Palaeo‐current measurements were taken from foreset dip directions of large‐sale cross‐bedded sandstones (e.g. High & Picard, 1974; Miall, 1974; Dasgupta, 2002) to understand and reconstruct the dominant wind regimes, sediment pathways and source dynamics (Miall, 2016) across south‐west Gondwana during the Early Jurassic. Classification and interpretation of facies associations 3 to 5 is based on Carroll & Bohacs (1999).…”

Section: Methodsmentioning

confidence: 99%

Lake dynamics in an Early Jurassic desert: Evidence from the Clarens Formation in southern Africa

Head

Bordy

2022

Sedimentology

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Interdune deposits are sensitive to climatic fluctuations and ancient interdune lacustrine systems can reveal the drivers of erg dynamics through time and space. This southern African study details the dynamics of interdune deposition in a vast ancient desert system that was active over Pangaea in the Middle Mesozoic and formed part of one of the largest known sand seas in Earth's history. Focusing on the Sinemurian to Pliensbachian Clarens Formation in the main Karoo Basin (south-west Gondwana), three facies associations were identified that formed in meso-scale and macro-scale lakes amongst aeolian dunes and sand sheets of the Clarens erg system. The northern facies association is restricted to interdune hollows within an actively climbing dune system. High-sediment availability and high-wind speeds limited the space available for these meso-scale lakes to expand. Here, migrating dunes outpaced the water table rise promoting the formation of discontinuous lenses of lake deposits, as is typical in erg centres. The southern facies associations developed both in spatially isolated meso-scale lakes, where flooding was controlled by groundwater inundation (water table rise), as well as in macro-scale lakes, where flooding was related to groundwater inundation and floods (surface runoff) that induced terminal splays. Relative to the north, the southern facies associations, with their more significant thickness and lateral extent, show that, here, the basin was characterized by a higher rate of relative subsidence. Moreover, the southern lake systems were established along the erg's margin, where the interdunes expanded during pluvial phases. Ultimately, the facies associations in the Clarens Formation show that the widespread arid conditions in the Early Jurassic of south-west Gondwana were subjected to prolonged and repeated pluvial phases in an otherwise harsh environment. Given the prominence of Jurassic aeolianites across Pangea, this study provides a southern African perspective on global palaeoerg dynamics and Early Jurassic climatic shifts.

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Section: Methodsmentioning

confidence: 99%

Lake dynamics in an Early Jurassic desert: Evidence from the Clarens Formation in southern Africa

Head

Bordy

2022

Sedimentology

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“…Multiple parameters influence the dynamics of the generation and preservation of sedimentary rocks, challenging their recognition in the stratigraphic record. In continental to marine depositional systems, the type and volume of sediment that may be preserved over geologic time is mainly controlled by the interplay of regional tectonics, eustatic fluctuations, climate, sedimentary supply, ecological boundary conditions, and the intrinsic energy of the environment (Catuneanu, 2006; Fragoso et al, 2022; Holbrook & Miall, 2020; Matenco & Haq, 2020; Miall, 2016; Miall et al, 2021; Strasser et al, 1999, 2006). These parameters act at various temporal and spatial scales and amplitudes, radically altering the physiography of a sedimentary basin across time and leaving their imprints on the stratigraphic record through cycles at multiple scales (Fragoso et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

Middle Jurassic multi‐scale transgressive–regressive cycles: An example from the Lusitanian Basin

Magalhães

Terra²,

Guadagnin

et al. 2023

The Depositional Record

104

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Multi‐scale transgressive–regressive cycles from the mid‐Jurassic were recognised in the Central Lusitanian Basin, Portugal. These cycles allow the depositional evolution of the basin to be better understood and aid in the construction of stratigraphic sequences composed of three hierarchies. The stacking pattern of high‐frequency transgressive–regressive sequences forms larger clusters that define medium‐frequency transgressive–regressive sequences. Likewise, the stacking pattern of medium‐frequency transgressive–regressive sequences generates two Bathonian–early Callovian low‐frequency transgressive–regressive sequences. Integration of several methods supported the interpretation of facies associations representing clastic deposition in offshore to shoreface environments and carbonate sediments in outer to inner ramp settings. New data from calcareous nannofossils and dinoflagellate assemblages constrained the interval's Bathonian–early Callovian age, thus unveiling the Middle–Upper Jurassic disconformity and filling the Middle Jurassic stratigraphic record gap in the Central Lusitanian Basin. This study may be helpful for similar successions in Tethyan domains and comparable depositional settings elsewhere.

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“…In some instances, subsidiary trenches were excavated at right angles to and intersecting the main trenches to create a ‘T‐piece’. The intersecting trench walls provided three‐dimensional (3D) exposures of the sediments and facilitated the detailed mapping of the sedimentary facies (Miall, 2016). The surface topography, marker units and, in places, facies boundaries were determined by a qualified surveyor using a Leica digital theodolite (Leica Microsystems, Wetzlar, Germany).…”

Section: Methodsmentioning

confidence: 99%

Anatomy of a diamondiferous gravel barrier spit at the palaeo‐Orange River mouth, south‐western Namibia

Spaggiari

Bordy

2023

Sedimentology

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The sedimentary facies architecture of a Plio-Pleistocene diamond-bearing gravel barrier spit within the palaeo-Orange River mouth in south-western Namibia has been revealed during onshore mining activities. Four sedimentary facies associations build this ancient coastal landform and have been interpreted, from a seaward to landward direction, as sediments in: (i) the foreshore, represented by an intertidal beach; (ii) a subtidal spit platform on which the spit developed; (iii) storm-constructed spit head recurves on the landward side of the spit; and (iv) an estuarine back-barrier. This sedimentary record reflects an evolving spit that grew in response to a combination of marine and fluvial processes in a wavedominated, high-energy coastal regime. Here, the southern Atlantic Ocean aggressively dispersed sediment delivered by a Plio-Pleistocene Orange River, ensuring that the fine-grained sediments were removed to allow only the gravel fraction to build up along the coastline. This extreme dispersal of sediment also precluded the construction of a classic delta; hence sediment storage offshore of the river mouth was limited and spit growth was dependent on the direct supply of river sediment. In response to the intermittent supply of sediment, spit growth and decay alternated during periods of sediment abundance and starvation, respectively. During positive sediment budget, the spit extended northward and cut off parts of the mainland to form an estuarine back-barrier. Foreshore and spit head progradation was sustained under these conditions, and formed a beach-ridge plain with a topographic expression of several coast-parallel ridges that curved at the spit head into the back-barrier. Spit extension and recurve development were controlled by a combination of high sediment supply, a vigorous longshore drift and powerful waves approaching from various directions. This Plio-Pleistocene coastal landform in Namibia offers a depositional model relevant to graveldominated barrier spits near river mouths along wave-dominated clastic coasts.

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Stratigraphy: The Modern Synthesis

Cited by 7 publications

References 200 publications

Lake dynamics in an Early Jurassic desert: Evidence from the Clarens Formation in southern Africa

Lake dynamics in an Early Jurassic desert: Evidence from the Clarens Formation in southern Africa

Middle Jurassic multi‐scale transgressive–regressive cycles: An example from the Lusitanian Basin

Anatomy of a diamondiferous gravel barrier spit at the palaeo‐Orange River mouth, south‐western Namibia

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