A structural study of thermal tufas using ground-penetrating radar

McBride, John H.; Guthrie, W. Spencer; Faust, David L.; Nelson, Stephen T.

doi:10.1016/j.jappgeo.2011.09.011

Cited by 11 publications

(6 citation statements)

References 26 publications

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“…However, terraced, fluvial carbonate deposits appear to be a particularly promising tool for understanding the environmental and palaeohydrographical evolution of an area, since the morphology and depositional features of carbonate terraces are generally well-preserved by early lithification (Ord oñez et al, 2005;Schulte et al, 2008;Zentmyer et al, 2008;Ortiz et al, 2009;Capezzuoli et al, 2010). Although outcrops are commonly poor, the internal architecture of terrace deposits can be revealed by ground-penetrating radar, especially in areas where the water table is low McBride et al, 2012). Using this method, Pedley et al (2000) showed the former presence of an incised meandering limestone gorge below a tufa terrace and revealed details of a buried barrage-tufa succession.…”

Section: Landscape Evolutionmentioning

confidence: 99%

Decoding tufa and travertine (fresh water carbonates) in the sedimentary record: The state of the art

2013

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Traditionally, fresh water carbonate research has focused on the sedimentology and palaeontology of ancient lacustrine deposits. Lithofacies in such low-energy deposits are typically fine-grained, developed uniformly in a generally concentric distribution ('bulls-eye' pattern) and are predictable even when preserved imperfectly. In contrast, because of their local lithofacies and palaeontological complexities, fluvial carbonates were either delegated to a status of 'minor geomorphological features' or barely considered prior to the 1970s. This viewpoint was based on the depositional record of fluvial and spring-fed fresh water carbonates, which were considered to be restricted generally to localized karstic areas. Such deposits are often preserved as scattered patches of ambient temperature tufa. Occasionally, however, in active tectonic areas, localized travertine deposits are also developed from deeply circulating hydrothermal waters. With a few exceptions (for example, basins with high subsidence rates or in arid climate zones), these fresh water carbonates are prone to erosion from continuing river incision and thus may not be preserved in the geological record. A partial record of fluvial and springdeposited carbonates is often preserved in Quaternary deposits, but the record in older deposits is typically fragmentary and often diagenetically modified. Yet once their unique facies architecture (and specialized nomenclature) is understood, these carbonates provide an important record of past sedimentological cycles of great value in palaeoenvironmental landscape modelling. The emphasis of modern research is to acquire information that explains how active systems function. In this respect, tufas reveal much of how carbonate precipitation is a shared product of physico-chemical and microbiological biomediation processes. Likewise, travertines not only show an intimate interrelation with active tectonism but also hold great potential as monitors of past volcanic carbon dioxide emissions. In addition, both tufas and travertines contain palynological records that can be used as proxy indicators of climate change. Perhaps no other field of sedimentology has witnessed more developments and applications over such a brief period of study.

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Section: Landscape Evolutionmentioning

confidence: 99%

Decoding tufa and travertine (fresh water carbonates) in the sedimentary record: The state of the art

2013

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“…Porosities in the range of 28%–60% are common in carbonate rocks, such as tufas and speleothems, which fill recent or old caves (McBride et al . ; Araújo et al . ).…”

Section: Discussionmentioning

confidence: 99%

“…These carbonate reservoirs are formed by extensive systems of interconnected paleocaves, which typically have complex formation histories and well-pronounced vertical and lateral heterogeneities (Loucks 1999). The reservoirs of the Permian Basin extend over thousands of metres, with widths of several hundred metres (McMechan et al 2002) and thicknesses on the order of a few which fill recent or old caves (McBride et al 2012;Araújo et al 2013). In fact, we measured the porosity of tufa samples in the paleocave in the central part of the road cut ( Fig.…”

Section: Discussionmentioning

confidence: 99%

ERT and GPR survey of collapsed paleocave systems at the western border of the Potiguar Basin in northeast Brazil

Júnior

Castro

Casas

et al. 2015

Near Surface Geophysics

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Collapsed paleocave systems are carbonate reservoirs with high internal spatial complexity that are the result of several stages of karst processes. Paleocave-related reservoirs can be spread over large areas with significant thicknesses that are favourable for hydrocarbon exploration. Nevertheless, few studies have provided a detailed understanding of the strong lateral heterogeneity of these reservoirs and their complex karst-controlled development using modern karst terrain analogues. To elucidate this issue, the internal architecture of a collapsed paleocave system has been mapped accurately at the western border of the Potiguar Basin in Northeastern Brazil. The collapsed paleocaves outcrop in an escarpment that delimits the carbonate platform from the transgressive phase of the basin. Electrical resistivity tomography (ERT) and ground-penetrating radar (GPR) sections were acquired parallel and perpendicular to a road cut and served to parameterize the geophysical signatures of the collapsed paleocaves and the host rocks. The collapsed paleocaves were mapped by identifying high-resistivity zones and high-amplitude ground-penetrating radar reflectors. In contrast, the host rocks are marked by low to intermediate resistivity and ground-penetrating radar reflections that range from low amplitude to almost transparent. The resistivity data and the ground-penetrating radar attribute of the rootsquare energy enabled the mapping of the complex spatial distribution of the collapsed paleocaves system. At depths of approximately 20 m, the paleocaves are more spread out and eventually become isolated while sometimes being connected vertically through shafts. However, at shallower levels, the paleocaves are interconnected by ducts or coalesce into a system of paleocaves that are hundreds of metres long over an area of 12000 m 2 . The results of the study show the detailed internal geometry of this paleocave system at a subseismic scale, which enables the identification of the connectivity pattern among these karst features and the porosity and total volume of the reservoir. This system could serve as an outcrop analogue for other collapsed paleocave carbonate reservoirs worldwide.

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“…This analysis permitted us to constrain a propagation velocity ranging from 78 to 113 m/µs with a mean value of 90 m/µs for the whole area. Propagation velocity is in the range of the obtained in similar settings (Annan, 1992;Dagallier et al, 2000;Kruse et al, 2000;Hill, 2003 Neal, 2004;Mukherjee et al, 2010;McBride et al, 2012). After surveying, a similar data processing was applied to each profile: through time-zero correction, filter of frequencies out of range, running average or stacking to avoid irregular surficial displacement (in order to avoid significant resolution looses during processing, each trigger was defined for 1024 samples and trig distance established over the horizontal resolution).…”

Section: Geophysical Surveymentioning

confidence: 99%

Late Pleistocene–Holocene palaeoenvironmental evolution of the Añamaza River valley (Iberian Range, NE Spain): Multidisciplinary approach on the study of carbonate fluvial systems

Luzón

Gauthier

Pérez

et al. 2017

Quaternary International

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A structural study of thermal tufas using ground-penetrating radar

Cited by 11 publications

References 26 publications

Decoding tufa and travertine (fresh water carbonates) in the sedimentary record: The state of the art

Decoding tufa and travertine (fresh water carbonates) in the sedimentary record: The state of the art

ERT and GPR survey of collapsed paleocave systems at the western border of the Potiguar Basin in northeast Brazil

Late Pleistocene–Holocene palaeoenvironmental evolution of the Añamaza River valley (Iberian Range, NE Spain): Multidisciplinary approach on the study of carbonate fluvial systems

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