Ordovician glacial paleogeography: Integration of seismic spectral decomposition, well sedimentological data, and glacial modern analogs in the Murzuq Basin, Libya

Bataller, F.J.; McDougall, Neil; Moscariello, Andrea

doi:10.1190/int-2018-0069.1

Cited by 10 publications

(7 citation statements)

References 45 publications

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“…Successions related to the Late Ordovician (Hirnantian) glaciations of Gondwana are widespread and well documented from North Africa and the Arabian Peninsula (Le Heron et al ., 2009). The dominantly glacifluvial and glacimarine successions indicate depositional environments with abundant meltwater and supply of sand‐grade sediment (Le Heron et al ., 2009; Bataller et al ., 2019). These conditions should favour the formation and preservation of upper‐flow‐regime bedforms, which indeed have been documented by a range of studies (Hirst et al ., 2002; Le Heron et al ., 2010, 2013, 2015; Hirst, 2012; Lang et al ., 2012; Girard et al ., 2012a,b, 2015; Moreau & Joubert, 2016).…”

Section: The Depositional Record Of Glacigenic Upper‐flow‐regime Bedformsmentioning

confidence: 99%

Bedforms and sedimentary structures related to supercritical flows in glacigenic settings

et al. 2020

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Upper-flow-regime bedforms, including upper-stage-plane beds, antidunes, chutes-and-pools and cyclic steps, are ubiquitous in glacigenic depositional environments characterized by abundant meltwater discharge and sediment supply. In this study, the depositional record of Froude near-critical and supercritical flows in glacigenic settings is reviewed, and similarities and differences between different depositional environments are discussed. Upper-flow-regime bedforms may occur in subglacial, subaerial and subaqueous environments, recording deposition by free-surface flows and submerged density flows. Although individual bedform types are generally not indicative of any specific depositional environment, some observed trends are similar to those documented in non-glacigenic settings. Important parameters for bedform evolution that differ between depositional environments include flow confinement, bed slope, aggradation rate and grain size. Cyclic-step deposits are more common in confined settings, like channels or incised valleys, or steep slopes of coarse-grained deltas. Antidune deposits prevail in unconfined settings and on more gentle slopes, like glacifluvial fans, sandrich delta slopes or subaqueous (ice-contact) fans. At low aggradation rates, only the basal portions of bedforms are preserved, such as scour fills related to the hydraulic-jump zone of cyclic steps or antidune-wave breaking, which are common in glacifluvial systems and during glacial lake-outburst floods and (related) lake-level falls. Higher aggradation rates result in increased preservation potential, possibly leading to the preservation of complete bedforms. Such conditions are met in sediment-laden j€ okulhlaups and subaqueous proglacial environments characterized by expanding density flows. Coarser-grained sediment leads to steeper bedform profiles and highly scoured facies architectures, while finer-grained deposits display less steep bedform architectures. Such differences are in part related to stronger flows, faster settling of coarse clasts, and more rapid breaking of antidune waves or hydraulic-jump formation over hydraulically rough beds.

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Section: The Depositional Record Of Glacigenic Upper‐flow‐regime Bedformsmentioning

confidence: 99%

Bedforms and sedimentary structures related to supercritical flows in glacigenic settings

et al. 2020

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“…Seismic interpretations of Paleozoic glacial valley fill in other parts of the world (Bache et al., 2012; Bataller et al., 2019) reveal complex stratigraphy representative of repeated glacier advances and retreats, with additional complications arising from subsequent erosion, deformation, and sedimentation events. Lack of a well penetration here precludes precise characterization of the nature and age of the valley fill.…”

Section: Resultsmentioning

confidence: 99%

“…Many seismic studies of Quaternary glacial valleys focus on the sediment fill and associated potential for groundwater resources or waste disposal (e.g., Bleibinhaus & Hilberg, 2012; Brückl et al., 2010; Burschil et al., 2018; de Franco et al., 2009; Pomper et al., 2017). In contrast, few studies have presented seismic imaging of pre‐Quaternary glacial valleys, mostly in the context of hydrocarbon potential within the sediment fill (Bache et al., 2012; Bataller et al., 2019; Vesely et al., 2021).…”

Section: Introductionmentioning

confidence: 99%

Seismic Reflection and Electrical Resistivity Imaging Support Pre‐Quaternary Glaciation in the Rocky Mountains (Unaweep Canyon, Colorado)

Patterson

Behm

Chwatal

et al. 2021

Geophysical Research Letters

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Landscape shapes record processes of formation. In particular, fluvial processes typically exhibit V-shaped profiles with steep slopes, whereas glacial processes carve U-shaped valleys with variable slopes and overdeepenings (MacGregor et al., 2000;Prasicek et al., 2014). Overdeepened valleys are those with depths extending below fluvial base level (Preusser et al., 2010) and are key elements of glacial landscapes where warm-bed conditions exist(ed) (e.g., Benn & Evans, 1998;Cook & Swift, 2012). Such valleys are characterized by closed topographic depressions and are commonly eroded several hundred meters below the base level (Fiebig et al., 2010;Menzies, 1995;Preusser et al., 2010). Overdeepening on basement is unknown in canyons carved exclusively by fluvial processes (Cook & Swift, 2012;Huuse & Lykke-Andersen, 2000;Linton, 1963); rather, overdeepenings are considered "unambiguous features of glacially sculpted landscapes" (Pomper et al., 2017). Overdeepening occurs in cirques, valley outlets of alpine glaciers, and fjords and valleys draining continental ice sheets, related to perturbations in the bed that amplify the action of high-pressure meltwater (Hooke, 1991).Seismic imaging has been widely used to characterize Quaternary glacial valleys and, together with drilling and other subsurface data, has demonstrated the distinctive propensity for glacial processes to produce not Abstract Unaweep Canyon (Uncompahgre Plateau, Colorado) represents an enigmatic landscape with a complex evolution. Interpretations for its origin have ranged from ancestral fluvial erosion in the late Cenozoic to glacial erosion in the Paleozoic, or some combination thereof, with significant implications for global climatic and large-scale tectonic reconstructions. To address the conflicting interpretations, we acquired a high-resolution seismic reflection profile to investigate the depth, structure, and sedimentary infill in the canyon. The data set is further complemented with an electrical resistivity survey. Integrated with other geophysical and geological data, the results show an overdeepened Precambrian basement with transverse U shape and support the hypothesis of a pre-Quaternary glacial origin. Our data constitute the first detailed image of a buried pre-Quaternary glacial valley in North America; if substantiated with core studies, these results have far-reaching implications for our understanding of global ice houses as well as the tectonic conditions, enabling preservation of such systems. Plain Language SummaryThe shape of valleys depends on the processes that created them.Broad valleys with the transverse shape of a "U" are distinct signs of glaciers, which carved the valley in the bedrock. Since old valleys are filled up with sediments, we need geophysical tools to image their structure in the buried subsurface. Using such tools, we have found a buried U-shaped valley in western Colorado. Since we know from other observations that there were no glaciers in this specific location in the last ice age, the valley must have ...

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“…Gas fields in North Africa, including In Amenas and Elephant fields, are hosted in glaciogenic rocks (Mamuniyat Formation) deposited over a glacial erosional surface (GES) (e.g. Bataller et al, 2019;Hirst, 2012;Le Heron et al, 2009Lüning et al, 2000). The reservoir intervals show a broad spectrum of grainsizes, multiple minor internal erosional contacts and at least two extensive GESs indicating two or more ice sheet re-advances (Heron et al, 2015;Le Heron et al, 2009).…”

Section: Implications For Hydrocarbon Explorationmentioning

confidence: 99%

A conceptual model for glaciogenic reservoirs: From landsystems to reservoir architecture

Kurjański

Rea

Spagnolo

et al. 2020

Marine and Petroleum Geology

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Ordovician glacial paleogeography: Integration of seismic spectral decomposition, well sedimentological data, and glacial modern analogs in the Murzuq Basin, Libya

Cited by 10 publications

References 45 publications

Bedforms and sedimentary structures related to supercritical flows in glacigenic settings

Bedforms and sedimentary structures related to supercritical flows in glacigenic settings

Seismic Reflection and Electrical Resistivity Imaging Support Pre‐Quaternary Glaciation in the Rocky Mountains (Unaweep Canyon, Colorado)

A conceptual model for glaciogenic reservoirs: From landsystems to reservoir architecture

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