scholarly journals Late Pliocene-Pleistocene incision in the Ebro Basin (North Spain)

2021 ◽  
Vol 192 ◽  
pp. 30
Author(s):  
Vincent Regard ◽  
Arnaud Vacherat ◽  
Stéphane Bonnet ◽  
Frédéric Mouthereau ◽  
Jesper Nørgaard ◽  
...  
Keyword(s):  
Cosmogenic Nuclides ◽  
Middle Pleistocene ◽  
Ebro Basin ◽  
Fluvial Terrace ◽  
Climate Fluctuations ◽  
River Terraces ◽  
River Incision ◽  
Middle Pleistocene Transition ◽  
Age Constraints ◽  
Fluvial Network

The Ebro Basin constitutes the central part of the southern foreland of the Pyrenees. It was endorheic during the Cenozoic and accumulated sediments. By the end of the Miocene, erosion and river incision reconnected the basin to the Mediterranean Sea, establishing a post-opening drainage network. Those rivers left terraces that we study in this work. We first synthesize previous works on river terraces that are widely dispersed in the basin. We provide new age constraints, up to 3 Ma, obtained thanks to cosmogenic nuclides using both profile and burial methods. We derive a unified fluvial terrace chronology and a homogenized map of the highest terraces over the entire Ebro Basin. The dated terraces labeled A, B, C, D, and E are dated to 2.8 ± 0.7 Ma, 1.15 ± 0.15 Ma, 850 ± 70 ka, 650 ± 130 ka, and 400 ± 120 ka, respectively. The chronology proposed here is similar to other sequences of river terraces dated in the Iberian Peninsula, around the Pyrenees, and elsewhere in Europe. The oldest terraces (A, B, C) are extensive, indicating they form a mobile fluvial network while from D to present, the network was stable and entrenched in 100 to 200 m-deep valleys. The transition from mobile to fixed fluvial network is likely to have occurred during the Middle Pleistocene Transition (MPT, between 0.7 and 1.3 Ma), when long-period/high-intensity climate fluctuations were established in Europe. We estimate that between 2.8–1.15 Ma and present, the incision rates have tripled.

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 Sediment burial dating using terrestrial cosmogenic nuclides

2008 ◽  
Vol 57 (1/2) ◽  
pp. 210-225 ◽  
Author(s):  
Andreas Dehnert ◽  
Christian Schlüchter
Keyword(s):  
Cosmogenic Nuclides ◽  
Quaternary Geology ◽  
Alluvial Fans ◽  
Bearing Material ◽  
Sedimentary Deposits ◽  
River Terraces ◽  
River Incision ◽  
Scientific Disciplines ◽  
Numerical Dating

Abstract. Burial dating using in situ produced terrestrial cosmogenic nuclides is a relatively new method to date sediments and quantify geomorphological processes such as erosion, accumulation and river incision. Burial dating utilises the decay of previously in situ produced cosmogenic nuclides and can be applied to sedimentary deposits such as cave fillings, alluvial fans, river terraces, delta deposits, and dunes. Using the established 10Be/26Al nuclide pair allows numerical dating of quartz bearing material from ~100 ka to 5 Ma, where other dateable material is often unavailable. To date, a number of studies have demonstrated the successful application of in situ produced cosmogenic nuclides in various scientific disciplines, such as Quaternary geology, geomorphology and palaeoanthropology. However, insufficiently defined physical properties such as nuclide half lives and complex depth dependent nuclide production rates result in relatively large uncertainties. Nevertheless, burial dating represents a promising method for determining numerical ages.

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

<p>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 >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·ka<sup>-1</sup> from ca. 1 to 0.7 Ma. Later, incision rates dropped to ~0.08 m·ka<sup>-1</sup> during Middle Pleistocene, and 0.05 m·ka<sup>-1</sup> 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.</p>

Pleistocene Terraces of the Alto Henares (Guadalajara), Spain

1972 ◽  
Vol 2 (4) ◽  
pp. 473-486 ◽  
Author(s):  
Bruce G. Gladfelter
Keyword(s):  
Radiocarbon Dating ◽  
Drainage System ◽  
Middle Pleistocene ◽  
Ebro Basin ◽  
Lower Paleolithic ◽  
Lower Pleistocene

A suite of four terraces in the upper Rio Henares drainage system (Rio Tajo basin) now provides a partial geomorphological link between the Middle Pleistocene, Lower Paleolithic archeological sites at Ambrona and Torralba (upper Ebro basin) and those in the vicinity of Madrid. The Campiña and Low Terrace features are shown by radiocarbon dating to be of Holocene and Würm ages, respectively, while the Middle and High Terraces are best designated as being Middle and Lower Pleistocene ages, respectively. Stratigraphic relationships between the upper and lower Rio Henares segments need to be established.

Area of distribution and conditions of loess forming in the South Urals

2020 ◽  
pp. 16-30
Author(s):  
S. S. Popov ◽  
G. N. Shilova ◽  
A. O. Khotylev
Keyword(s):  
Middle Pleistocene ◽  
South Urals ◽  
Textural Features ◽  
Alluvial Fans ◽  
The South ◽  
Drainage Basins ◽  
Fluvial Terrace ◽  
Palynological Data ◽  
The Third ◽  
Lithological Composition

The report presents the results of comprehensive studies of loess-like formations that are common within drainage basins of Ay and Yuruzan rivers (South Urals). Loess complexes associated with the third fluvial terrace. The lithological composition, structural and textural features indicate that the loess were formed like the part of alluvial fans, planned under the third fluvial terrace. The obtained palynological data indicate the formation of deposits in the Middle Pleistocene during the Odintsovo interglacial and Moscow glaciation.

A New Method for Determining Thickness of River Incision Layers in High Mountain and Deep River Valley Areas

2015 ◽  
Vol 744-746 ◽  
pp. 407-412
Author(s):  
Ya Qun Liu ◽  
Hai Bo Li ◽  
Qi Tao Pei ◽  
Jing Sen Liu
Keyword(s):  
River Valley ◽  
New Method ◽  
High Mountain ◽  
River Terraces ◽  
River Incision ◽  
North Water ◽  
History Of ◽  
Formation And Evolution ◽  
Project Site

In high mountain and deep river valley areas, geological materials of river valley evolution are often missing or incomplete. To address this problem, tectonic movements at project site are analyzed using mathematical statistics based on the analysis of formation and evolution history of river terraces, and then a new method to determine the thickness of river incision layers is proposed. Taking Jiata dam area at the Western Route of South-to-North Water Transfer Project in China for an example, the reliability and reasonability of the proposed method are validated through a case study.

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