scholarly journals Quantifying faulting and base level controls on syn‐rift sedimentation using stratigraphic architectures of coeval, adjacent Early‐Middle Pleistocene fan deltas in Lake Corinth, Greece

2019 ◽  
Vol 31 (6) ◽  
pp. 1040-1065 ◽  
Author(s):  
Bonita J. Barrett ◽  
Richard E. LL. Collier ◽  
David M. Hodgson ◽  
Robert L. Gawthorpe ◽  
Robert M. Dorrell ◽  
...  
Keyword(s):  
Middle Pleistocene ◽  
Base Level ◽  
Fan Deltas

scholarly journals Cosmogenic burial dating of in cave-deposited alluvium: unravelling long-term incision rates and complex speleogenesis in multi-level cave systems

2020 ◽  
Author(s):  
Gilles Rixhon ◽  
Didier L. Bourlès ◽  
Régis Braucher ◽  
Alexandre Peeters ◽  
Alain Demoulin
Keyword(s):  
Early Pleistocene ◽  
Middle Pleistocene ◽  
Fluvial Terrace ◽  
Base Level ◽  
Cave System ◽  
River Incision ◽  
Order Of Magnitude ◽  
History Of ◽  
Multi Level

<p>Multi-level cave systems record the history of regional river incision in abandoned alluvium-filled phreatic passages which, mimicking fluvial terrace sequences, represent former phases of fluvial base-level stability. In this respect, cosmogenic burial dating of in cave-deposited alluvium (usually via the nuclide pair <sup>26</sup>Al/<sup>10</sup>Be) represents a suitable method to quantify the pace of long-term river incision. Here, we present a dataset of fifteen <sup>26</sup>Al/<sup>10</sup>Be burial ages measured in fluvial pebbles washed into a multi-level cave system developed in Devonian limestone of the uplifted Ardenne massif (eastern Belgium). The large and well-documented Chawresse system is located along the lower Ourthe valley (i.e. the main Ardennian tributary of the Meuse river) and spans altogether an elevation difference exceeding 120 m.</p><p>The depleted <sup>26</sup>Al/<sup>10</sup>Be ratios measured in four individual caves show two main outcomes. Firstly, computed burial ages ranging from ~0.2 to 3.3 Ma allows highlighting an acceleration by almost one order of magnitude of the incision rates during the first half of the Middle Pleistocene (from ~25 to ~160 m/Ma). Secondly, according to the relative elevation above the present-day floodplain of the sampled material in the Manants cave (<35 m), the four internally-consistent Early Pleistocene burial ages highlight an “anomalous” old speleogenesis in the framework of a gradual base-level lowering. They instead point to intra-karsting reworking of the sampled material in the topographically complex Manants cave. This in turn suggests an independent, long-lasting speleogenetic evolution of this specific cave, which differs from the <em>per descensum</em> model of speleogenesis generally acknowledged for the regional multi-level cave systems and their abandoned phreatic galleries. In addition to its classical use for inferring long-term incision rates, cosmogenic burial dating can thus contribute to better understand specific and complex speleogenetic evolution.</p>

scholarly journals Anatomy, Age and Origin of an Intramontane Top Basin Surface (Sorbas Basin, Betic Cordillera, SE Spain)

2018 ◽  
Author(s):  
Martin Stokes ◽  
Anne E. Mather ◽  
Ángel Rodés ◽  
Samantha H. Kearsey ◽  
Shaun Lewin
Keyword(s):  
Growth Patterns ◽  
Alluvial Fan ◽  
Betic Cordillera ◽  
Early Pleistocene ◽  
Middle Pleistocene ◽  
Surface Erosion ◽  
Se Spain ◽  
Surface Formation ◽  
Base Level ◽  
Basin Surface

Collisional mountain belts commonly develop intramontane basins from mechanical and isostatic subsidence during orogenic development. These frequently display a relict top surface, evidencing a change interval from basin infilling to erosion often via capture or overspill. Such surfaces provide markers that inform on orogenic growth patterns via climate and base level interplay. Here, we describe the top surface from the Sorbas Basin, a key intramontane basin within the Betic Cordillera (SE Spain). The surface is fragmentary comprising high elevation hilltops and discontinuous ridges developed onto the variably deformed final basin infill outcrop (Gochar Formation). We reconstruct surface configuration using DEM interpolation and apply 10Be/26Al cosmonuclides to assess surface formation timing. The surface is a degraded Early Pleistocene erosional pediment developed via autogenic switching of alluvial fan streams under stable dryland climate and base level conditions. Base level lowering since the Middle Pleistocene focused headwards incision up interfan drainages, culminating in fan head capture and fan morphological preservation within the abandoned surface. Post abandonment erosion has lowered the basin surface by 31 m (average) and removed ~5.95 km3 of fill. Regional basin comparisons reveal a phase of Early Pleistocene surface formation, marking landscape stability following the most recent Pliocene-Early Pleistocene mountain building. Post-surface erosion rate quantification is low and in accordance with 10Be denudation rates typical of the low uplift Betic Cordillera.

scholarly journals Constraining Quaternary erosion of the Campine Plateau (NE Belgium) using Bayesian inversion of an in-situ produced <sup>10</sup>Be concentration depth profile

2016 ◽  
Author(s):  
Koen Beerten ◽  
Eric Laloy ◽  
Veerle Vanacker ◽  
Bart Rogiers ◽  
Laurent Wouters
Keyword(s):  
Depth Profile ◽  
Erosion Rate ◽  
Current Knowledge ◽  
Middle Pleistocene ◽  
Bayesian Inversion ◽  
Model Inversion ◽  
Base Level ◽  
10Be Concentration ◽  
Concentration Depth Profile

Abstract. The rate at which low-lying sandy areas in temperate regions, such as the Campine area (NE Belgium), have been eroding during the Quaternary is a matter of debate. Current knowledge on the average pace of landscape evolution in the Campine area is largely based on geological inferences and modern analogies. We applied Bayesian inversion to an in-situ produced 10Be concentration depth profile in fluvial sand, sampled on top of the Campine Plateau, and inferred the average long-term erosion rate together with three other parameters, i.e., the surface exposure age, inherited 10Be concentration and sediment bulk density. The inferred erosion rate of 44 ± 9 mm/kyr (1σ) is relatively large in comparison with landforms that erode under comparable (palaeo-)climates elsewhere in the world. We evaluate this value in the light of the erodibility of the substrate and sudden base level lowering during the Middle Pleistocene. A denser sampling scheme of a two-nuclide concentration depth profile would allow to include more parameters in the model inversion and further reduce their uncertainty.

scholarly journals Anatomy, Age and Origin of an Intramontane Top Basin Surface (Sorbas Basin, Betic Cordillera, SE Spain)

2018 ◽  
Author(s):  
Martin Stokes ◽  
Anne E. Mather ◽  
Ángel Rodés ◽  
Samantha H. Kearsey ◽  
Shaun Lewin
Keyword(s):  
Growth Patterns ◽  
Alluvial Fan ◽  
Betic Cordillera ◽  
Early Pleistocene ◽  
Middle Pleistocene ◽  
Surface Erosion ◽  
Se Spain ◽  
Surface Formation ◽  
Base Level ◽  
Basin Surface

Collisional mountain belts commonly develop intramontane basins from mechanical and isostatic subsidence during orogenic These frequently display a relict top surface, evidencing a change&nbsp; interval from basin infilling&nbsp; to erosion often via&nbsp; capture&nbsp; or overspill. &nbsp;Such surfaces provide&nbsp; markers&nbsp; that&nbsp; inform&nbsp; on orogenic&nbsp; growth patterns&nbsp; via&nbsp; climate&nbsp; and&nbsp; base level Here, we describe the top surface from the Sorbas Basin, a key intramontane basin within the Betic Cordillera (SE Spain). The surface is fragmentary comprising high elevation hilltops and discontinuous ridges developed onto the variably deformed final basin infill outcrop (Gochar Formation). We reconstruct surface configuration using DEM interpolation and apply 10Be/26Al cosmonuclides to assess surface formation The surface is an Early Pleistocene erosional pediment developed via autogenic switching of alluvial fan streams under stable dryland climate and base level Base level lowering since the Middle Pleistocene focused headwards incision up interfan drainages, culminating in fan head capture and fan morphological preservation within the abandoned Post abandonment erosion has lowered the basin surface by 31 m (average) and removed ~5.95 km3 of fill. Regional basin comparisons reveal a phase of Early Pleistocene surface formation, marking landscape stability following the most recent Pliocene-Early Pleistocene mountain Post-surface erosion rate quantification is low and in accordance with 10Be denudation rates typical of the low uplift Betic

scholarly journals Paleohydrogeology of the Karstic System of Fuentetoba Spring (Soria, Spain): An Interdisciplinary Approach

2021 ◽  
Vol 13 (13) ◽  
pp. 7236
Author(s):  
Eugenio Sanz Pérez ◽  
Cristina Fonolla ◽  
Ignacio Menéndez Pidal ◽  
Pablo Rosas Rodriguez
Keyword(s):  
Interdisciplinary Approach ◽  
Middle Pleistocene ◽  
Quaternary Period ◽  
Unique Type ◽  
Aquifer System ◽  
Base Level ◽  
History Of ◽  
Interdisciplinary Study ◽  
Natural Recharge ◽  
Hydraulic Balance

As a preliminary phase in the conservation and sustainable management of a karst system in Fuentetoba, Soria, Spain, an interdisciplinary study was carried out to determine its hydrogeological evolution. The hydrogeological history of this aquifer system began during the late Miocene, where discharges were driven by paleo-emergences in the moor, and associated conduits were developed under phreatic (or vadose) conditions—for example, the upper syngenetic galleries in the main known karst cave (Majada del Cura cave). Later on, the nearby karstic massifs, a general flattening of the relief, occurred during the Quaternary Period, during which the karstic base level had been in decline. The aquifer flow was then derived and modified towards the Fuentetoba spring from the earliest stages through the galleries of the aforementioned cave. The observations made in this cave indicate the existence of a unique type of hydrogeological organization. The hypogean network is the result of the excavation of the same water flow that has been entrenching and abandoning the vadose regimen toward the free regimen. The dating of the tuffaceous buildings, associated with the emergences, indicates that since almost the Middle Pleistocene, flow lines have converged in the Fuentetoba spring, inducing a high grade of karstification in the saturated zone of the syncline basin. Moreover, a major drainage conduit was developed by dissolution. During the late Upper Pleistocene, an essential component of the groundwater flow had been derived towards the source of the Mazos River spring. Tufa and paleogour datings in caves indicate that the aquifer has undergone different climatic stages during the latest Quaternary and, therefore, different feeding and recharge processes. These tufas and paleogours are interrelated as well, as they are associated with the warm stages during the most recent Quaternary, according to the regional context, when there was less natural recharge. The simulation of the springs’ flow enabled an approximate quantification of the variation in the aquifer’s hydraulic balance during the different climatic stages. For example, during the last glaciation, the natural recharge was impacted by snowmelt and increased by 160%.

Evolution of Quaternary cave levels in low-relief karst regions: influence of fluvial incision and speleoinception of chalk caves in northern France

2020 ◽  
Author(s):  
Daniel Ballesteros ◽  
Carole Nehme ◽  
Andrew Farrant ◽  
Dominique Todisco ◽  
Diana Sahy ◽  
...  
Keyword(s):  
Laminated Sediments ◽  
Early Pleistocene ◽  
Middle Pleistocene ◽  
Northern France ◽  
Base Level ◽  
River Terraces ◽  
River Incision ◽  
Fluvial Incision ◽  
Relevant Role ◽  
Conduit Development

&lt;p&gt;In many lowland areas, fluvial incision is usually relatively slowly and another factors as the stratigraphical control would play a relevant role. In the lower Seine valley of Northern France, cave systems developed in the sub-horizontal Upper Cretaceous chalk of the Anglo-Paris Basin offer the potential to constrain the Quaternary evolution of the Seine valley and to test the role of speleo-inception theory of conduit development in the chalk aquifer. Six chalk caves, with a combined length of over 5.7 km were studied in detail. In each studied cave, data on the passage morphology, cave deposits (speleothem and sediments) and stratigraphical control were recorded. Cave levels were defined based on geomorphological evidence and altitudinal cave passage analyses. The chronology of cave development and abandonment was constrained by ten U-Th speleothem dates and 144 palaeomagnetic samples collected from laminated sediments within the caves. Four regional cave levels were identified at 10, 40, 75-80, and 85-90 m asl, showing 1% slope to the Seine estuary. Each cave level is formed by phreatic and epiphreatic conduits enlarged by paragenesis, showing branch work or maze patterns. Cave infill corresponds mainly to clayey to silty sediments that occupy the majority of the karst conduits. Locally, sands and pebbles occur, and speleothems are relatively scarce. Palaeomagnetic and U-Th data show that these cave levels developed sequentially from &gt;1.06 ka to c. 300 ka, ca. 78% of them in relation to prominent Turonian, Coniacian and Santonian hardgrounds as well as sheet- and semi-tabular flint bands. Their age correlates with the estimated age of the lower river terraces from limited previously published OSL, palaeontological and U-Th dating, although new age data from the study cave improve the chronology of the higher-level river terraces. The combination of all this data suggests an initial slow rate of incision during the early Pleistocene, followed by a phase of more rapid river incision up to ~ 0.30 m&amp;#183;ka&lt;sup&gt;-1&lt;/sup&gt; from ca. 1 to 0.7 Ma. Later, incision rates dropped to ~0.08 m&amp;#183;ka&lt;sup&gt;-1&lt;/sup&gt; during Middle Pleistocene, and 0.05 m&amp;#183;ka&lt;sup&gt;-1&lt;/sup&gt; since the beginning of the Upper Pleistocene. In conclusion, fluvial incision constitutes also a relevant speleogenic factor in low-gradient areas as the Seine Basin, where conduit development was favoured at sites where suitable lithological inception horizons intercept the contemporary base level.&lt;/p&gt;

scholarly journals Anatomy, Age and Origin of an Intramontane Top Basin Surface (Sorbas Basin, Betic Cordillera, SE Spain)

Quaternary ◽  
2018 ◽  
Vol 1 (2) ◽  
pp. 15 ◽  
Author(s):  
Martin Stokes ◽  
Anne Mather ◽  
Angel Rodes ◽  
Samantha Kearsey ◽  
Shaun Lewin
Keyword(s):  
Growth Patterns ◽  
Alluvial Fan ◽  
Betic Cordillera ◽  
Early Pleistocene ◽  
Middle Pleistocene ◽  
Surface Erosion ◽  
Se Spain ◽  
Surface Formation ◽  
Base Level ◽  
Basin Surface

Collisional mountain belts commonly develop intramontane basins from mechanical and isostatic subsidence during orogenic development. These frequently display a relict top surface, evidencing a change interval from basin infilling to erosion often via capture or overspill. Such surfaces provide markers that inform on orogenic growth patterns via climate and base level interplay. Here, we describe the top surface from the Sorbas Basin, a key intramontane basin within the Betic Cordillera (SE Spain). The surface is fragmentary comprising high elevation hilltops and discontinuous ridges developed onto the variably deformed final basin infill outcrop (Gochar Formation). We reconstruct surface configuration using DEM interpolation and apply 10Be/26Al cosmonuclides to assess surface formation timing. The surface is a degraded Early Pleistocene erosional pediment developed via autogenic switching of alluvial fan streams under stable dryland climate and base level conditions. Base-level lowering since the Middle Pleistocene focused headwards incision up interfan drainages, culminating in fan head capture and fan morphological preservation within the abandoned surface. Post abandonment erosion has lowered the basin surface by 31 m (average) and removed ~5.95 km3 of fill. Regional basin comparisons reveal a phase of Early Pleistocene surface formation, marking landscape stability following the most recent Pliocene-Early Pleistocene mountain building. Post-surface erosion rate quantification is low and in accordance with 10Be denudation rates typical of the low uplift Betic Cordillera.

Representation of information in SEM by equal signal lines

1978 ◽  
Vol 36 (1) ◽  
pp. 144-145
Author(s):  
E. Rau ◽  
N. Karelin ◽  
V. Dukov ◽  
M. Kolomeytsev ◽  
S. Gavrikov ◽  
...  
Keyword(s):  
Electronic System ◽  
Space Distribution ◽  
Specimen Surface ◽  
Universal Method ◽  
Base Level ◽  
Signal Value ◽  
Information Signal ◽  
Fixed Base ◽  
Scanning Line ◽  
Amplitude Analyzer

There are different methods and devices for the increase of the videosignal information in SEM. For example, with the help of special pure electronic [1] and opto-electronic [2] systems equipotential areas on the specimen surface in SEM were obtained. This report generalizes quantitative universal method for space distribution representation of research specimen parameter by contour equal signal lines. The method is based on principle of comparison of information signal value with the fixed levels.Transformation image system for obtaining equal signal lines maps was developed in two versions:1)In pure electronic system [3] it is necessary to compare signal U (see Fig.1-a), which gives potential distribution on specimen surface along each scanning line with fixed base level signals εifor obtaining quantitative equipotential information on solid state surface. The amplitude analyzer-comparator gives flare sport videopulses at any fixed coordinate and any instant time when initial signal U is equal to one of the base level signals ε.

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