Stratigraphic records and variability of incised valleys and estuaries along French coasts

2010 ◽  
Vol 181 (2) ◽  
pp. 75-85 ◽  
Author(s):  
Eric Chaumillon ◽  
Bernadette Tessier ◽  
Jean-Yves Reynaud
Keyword(s):  
Environmental Changes ◽  
Promising Result ◽  
Sediment Supply ◽  
Controlling Factor ◽  
Incised Valley ◽  
Valley Fill ◽  
Incised Valleys ◽  
Valley Fills ◽  
Climate Events ◽  
Selection Of

Abstract Some of the striking results of the papers published in the special publication “French Incised valleys, estuaries and lagoons” of the Bulletin de la Société géologique de France are presented and compared. The selection of papers within this volume focuses exclusively on the recent progress made on modern French incised valleys, estuaries and lagoons around the coasts of France. Those papers together with abundant papers recently published on modern French incised valleys provide new insights for the knowledge on these sedimentary systems. The large amount of new results obtained is indebted to an extensive exploration within a large variety of estuaries, lagoons and coastal areas, from macrotidal tide-dominated, to microtidal wave-dominated, with also meso- to macrotidal mixed tide- and wave-dominated estuaries. These data allow comparing incised valleys within the same setting of tectonically stable and sediment starved margins, but showing contrasted conditions of hydrodynamics, sediment supply and bedrock control. At a stratigraphic level, sea-level variation is the main parameter controlling incised valley formation and sediment fill. The first-order controlling factor explaining the observed variations in valley fills is hydrodynamics. Three valley-fill categories are highlighted: tide-dominated, mixed tide-and-wave and wave-dominated, that match the classification based on hydrodynamics and morphology of present-day estuaries or lagoons. The second-order controlling factor explaining the observed variations in valley fills is the antecedent morphology of the bedrock, which in turn controls hydrodynamics and sediment supply. Finally, a promising result is the demonstration of the potential of incised valley fills to record high frequency environmental changes related to climate events and human activities.

Comparison of wave-and tide-dominated incised valleys: specific processes controlling systems tract architecture and reservoir geometry

2010 ◽  
Vol 181 (2) ◽  
pp. 171-181 ◽  
Author(s):  
Hugues Fenies ◽  
Gilles Lericolais ◽  
Henry W. Posamentier
Keyword(s):  
Sea Level ◽  
Drainage Basin ◽  
Tidal Inlet ◽  
The South ◽  
Littoral Drift ◽  
Incised Valley ◽  
Valley Fill ◽  
Incised Valleys ◽  
Valley Fills ◽  
Sequence Boundaries

Abstract This paper presents a comparison between the system tract architecture and the reservoir geometries of the Gironde and Leyre (Arcachon) incised-valley fills, both located within the Bay of Biscay 100 km apart. This study, based on high resolution seismic lines acquired by Ifremer on the continental shelf and onshore core and well data, illustrates that some features of the Gironde and Leyre valleys fills are similar while some others are not. The architecture of both valley fills is characterized by fifth order depositional sequences (corresponding to an interval from 120000 yr B.P. to present day). Both valleys are filled predominantly with transgressive systems tract, with associated poorly developed lowstand and highstand systems tracts. Key stratigraphic surfaces punctuate the valley-fill architecture and comprise deeply eroding tidal ravinement surfaces merged with and enhancing, earlier formed, fluvial-related erosive sequence boundaries. These tidal ravinement surfaces can be undulatory in form and in most places mark the basal boundary of the incised valleys. In contrast, nearly horizontal wave ravinement surfaces cap the incised-valley fills, extending over the adjacent interfluves. The Gironde and Leyre (Arcachon) valley fills exhibit two main stratigraphic differences: 1) transgressive systems tract sand bodies are ribbon shaped within the Gironde and tabular shaped within the Leyre; 2) lowstand systems tract deposits, represented by fluvial sediments, are preserved within the Gironde but absent within the Leyre. In a wave- and tide-dominated environment, the geometry of the sandbodies within the transgressive systems tract is a function of the tidal ravinement processes, which characterizes the estuary inlet. Two categories of tidal ravinement processes can be distinguished here: “anchored tidal ravinement” and “sweeping tidal ravinement”. The Gironde estuary is characterized by an “anchored tidal ravinement”. The tidal inlet has remained largely in a fixed location; littoral drift has not shifted the tidal inlet to the south because it is constrained by resistive Eocene carbonates that define the margins of the Gironde incised valley. In contrast, the Leyre estuary is characterized by a “sweeping tidal ravinement”. The inlet has been shifted approximately 30 km to the south by the formation of a littoral drift associated spit. This extensive lateral shifting was made possible by the fact that the incised valley was cut into unconsolidated, easily eroded Pleistocene sands. Within a wave- and tide-dominated environment, the preservation potential of the lowstand systems tract is a function of the size of the fluvial drainage basin. During lowstand time, the erosive power of the fluvial discharge was much greater within the much larger Gironde valley, consequently the fluvial sequence boundary was cut much deeper in the Gironde valley than within the Leyre valley and, correspondingly, the thickness of the associated fluvial deposits was commensurately greater. In response, the lowstand systems tract was not preserved within the Leyre valley fill because the depth of tidal ravinement erosion formed during the sea-level rise and associated transgression was greater than that associated with fluvial incision generated during the sea-level fall.

scholarly journals Autogenic delta progradation during sea-level rise within incised valleys

Geology ◽  
2020 ◽  
Author(s):  
L. Guerit ◽  
B.Z. Foreman ◽  
C. Chen ◽  
C. Paola ◽  
S. Castelltort
Keyword(s):  
Sediment Supply ◽  
Strong Decrease ◽  
Surface Evolution ◽  
Incised Valley ◽  
Sequence Stratigraphic ◽  
Base Level ◽  
Reservoir Models ◽  
Incised Valleys ◽  
Delta Progradation ◽  
The Trinity

Using a simple conceptual model of incised-valley evolution, we show that the classic sequence stratigraphic phenomenon of bayhead deltaic systems can be generated by purely autogenic progradation during the late stage of valley flooding. This transient “auto-advance” event occurs under conditions of constant base-level rise and sediment supply, and it results from a strong decrease of in-valley accommodation as base level rises toward the valley apex. We present a laboratory experiment to illustrate the plausibility of this mechanism and apply it to the incised valleys of the Trinity and Brazos Rivers (Texas, USA) as field case studies. Auto-advance can produce out-of-sequence regressive bayhead diastems during highstands similar to a transient change in allogenic forcing. Combined with other recent studies, our findings support the idea that mesoscale autogenic patterns are ubiquitous in the fluviodeltaic record and need to be more extensively incorporated into reconstructions of Earth surface evolution and reservoir models.

An integrated subsurface study of the Mannville–Colorado group boundary in the Cessford Field, Alberta

1994 ◽  
Vol 31 (3) ◽  
pp. 489-504 ◽  
Author(s):  
Indranil Banerjee ◽  
Santosh K. Ghosh ◽  
Hugh J. Abercrombie ◽  
Edward H. Davies
Keyword(s):  
Meteoric Water ◽  
Marine Transgression ◽  
Incised Valley ◽  
Paleontological Data ◽  
Inorganic Geochemistry ◽  
Incised Valleys ◽  
Valley Fills ◽  
Colorado Group ◽  
Group Boundary ◽  
Stratigraphic Boundary

The stratigraphic boundary separating the Mannville and the Colorado groups in Alberta, occupying incised valleys cut within the Upper Mannville strata, has previously been interpreted as an unconformity recording post-Mannville erosion followed by a late Albian marine transgression initiated by the deposition of the Joli Fou Shale and locally by the Basal Colorado Sandstone (both of the Colorado Group). Sedimentology, paleontology, organic and inorganic geochemistry, mineralogy, and petrography of strata above and below the unconformity or the sequence boundary have been studied in 106 samples from 37 wells within the Cessford Field covering an area of 3600 km2. Cores through the boundary show a distinct physical break represented by a scoured surface overlain by basal conglomerates. Paleontological data, based on dinoflagellates and foraminifers, show establishment of restricted marine conditions in the Basal Colorado times (initial transgression) and onset of open marine condition (maximum flooding) during the Joli Fou times. Although paleosol horizons have not been found near the boundary, influence of meteoric water in the Upper Mannville sandstones is inferred from development of spherulitic siderite and extensive early kaolinization of the feldspar, mica, and lithic grains. The absence of paleosol or fluvial strata within the incised valley fills suggests that the subaerial unconformity was modified by tidal erosion during the Joli Fou transgression.

The Holocene transgression as recorded by incised-valley infilling in a rocky coast context with low sediment supply (southern Brittany, western France)

2010 ◽  
Vol 181 (2) ◽  
pp. 115-128 ◽  
Author(s):  
David Menier ◽  
Bernadette Tessier ◽  
Jean-Noël Proust ◽  
Agnès Baltzer ◽  
Philippe Sorrel ◽  
...  
Keyword(s):  
Sediment Supply ◽  
Biological Origin ◽  
The Holocene ◽  
Incised Valley ◽  
Radiocarbon Age ◽  
Fine Grained ◽  
Holocene Transgression ◽  
Incised Valleys ◽  
Rocky Coast ◽  
Strong Control

Abstract A combination of morphobathymetric studies, very high-resolution seismics, core sampling and radiocarbon age data is used to investigate the latest stage of the sedimentary infilling of incised valleys in southern Brittany, related to the Holocene transgression. Owing to the bedrock morphology of this highly irregular rocky coast, two main types of valleys are defined by topographic rocky highs parallel to the coastline: 1) wide and rather shallow incised valleys offshore from a topographic sill, 2) narrow and relatively deep valleys between the sill and the coast (ria-type valley). The sedimentary infilling in both types of valleys becomes highly differentiated as the transgression advances onto the coastal area. In the wide valley seaward of the topographic sill, the infilling consists mainly of offshore heterolithic facies while, in the ria-type valley, most of the infill is composed of brackish mudflat deposits and estuarine tidal muddy sands. As the transgression proceeds, the rocky highs are flooded and the whole area is finally covered by the offshore facies. Radiocarbon dating indicates that: 1) the marine ravinement surface is highly diachronous (a few thousand years cross-shore); 2) the top of the offshore facies, coarser and very shelly, represents an episode of condensed sedimentation from about 3000 to 4000 years ago, amalgamating the maximum flooding surface (MFS) and the highstand systems tract (HST). However, we observe a muddy drape, strongly bioturbated in places, in the most proximal areas, overlying the offshore facies. It is thought to represent the modern and most recent stage of sedimentary infilling. This mud cover is made of fine-grained sediments of fluvial and biological origin, and is interpreted as a prograding HST. It reflects an increased influx, partly due to human activities. Finally, the main features of incised valley sedimentary infilling in a rocky coast context with low sediment supply can be characterized by (i) the very strong control of bedrock morphology, (ii) the diachronous character of the transgression, (iii) the late position of the MFS, and (iv), the highly reduced volume of the HST.

scholarly journals Environmental Changes and Cultural Transitions in SW Iberia during the Early-Mid Holocene

2021 ◽  
Vol 11 (8) ◽  
pp. 3580
Author(s):  
Cristina Val-Peón ◽  
Juan I. Santisteban ◽  
José A. López-Sáez ◽  
Gerd-Christian Weniger ◽  
Klaus Reicherter
Keyword(s):  
Dietary Habits ◽  
Environmental Changes ◽  
Source Area ◽  
Direct Access ◽  
Special Focus ◽  
Early Neolithic ◽  
Archaeological Data ◽  
Local Resources ◽  
Climate Events ◽  
The Impact

The SW coast of the Iberian Peninsula experiences a lack of palaeoenvironmental and archaeological data. With the aim to fill this gap, we contribute with a new palynological and geochemical dataset obtained from a sediment core drilled in the continental shelf of the Algarve coast. Archaeological data have been correlated with our multi-proxy dataset to understand how human groups adapted to environmental changes during the Early-Mid Holocene, with special focus on the Mesolithic to Neolithic transition. Vegetation trends indicate warm conditions at the onset of the Holocene followed by increased moisture and forest development ca. 10–7 ka BP, after which woodlands are progressively replaced by heaths. Peaks of aridity were identified at 8.2 and 7. 5 ka BP. Compositional, textural, redox state, and weathering of source area geochemical proxies indicates abrupt palaeoceanographic modifications and gradual terrestrial changes at 8.2 ka BP, while the 7.5 ka BP event mirrors a decrease in land moisture availability. Mesolithic sites are mainly composed of seasonal camps with direct access to the coast for the exploitation of local resources. This pattern extends into the Early Neolithic, when these sites coexist with seasonal and permanent occupations located in inland areas near rivers. Changes in settlement patterns and dietary habits may be influenced by changes in coastal environments caused by the sea-level rise and the impact of the 8.2 and 7.5 ka BP climate events.

scholarly journals Holocene sea level and climate interactions on wet dune slack evolution in SW Portugal: A model for future scenarios?

The Holocene ◽  
2018 ◽  
Vol 29 (1) ◽  
pp. 26-44 ◽  
Author(s):  
Manel Leira ◽  
Maria C Freitas ◽  
Tania Ferreira ◽  
Anabela Cruces ◽  
Simon Connor ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Environmental Changes ◽  
Sediment Accumulation ◽  
High Energy ◽  
Sediment Supply ◽  
Dune Slack ◽  
Ecological Stability ◽  
The Holocene ◽  
Climate Interactions

We examine the Holocene environmental changes in a wet dune slack of the Portuguese coast, Poço do Barbarroxa de Baixo. Lithology, organic matter, biological proxies and high-resolution chronology provide estimations of sediment accumulation rates and changes in environmental conditions in relation to sea-level change and climate variability during the Holocene. Results show that the wet dune slack was formed 7.5 cal. ka BP, contemporaneous with the last stages of the rapid sea-level rise. This depositional environment formed under frequent freshwater flooding and water ponding that allowed the development and post-mortem accumulation of abundant plant remains. The wetland evolved into mostly palustrine conditions over the next 2000 years, until a phase of stabilization in relative sea-level rise, when sedimentation rates slowed down to 0.04 mm yr−1, between 5.3 and 2.5 cal. ka BP. Later, about 0.8 cal. ka BP, high-energy events, likely due to enhanced storminess and more frequent onshore winds, caused the collapse of the foredune above the wetlands’ seaward margin. The delicate balance between hydrology (controlled by sea-level rise and climate change), sediment supply and storminess modulates the habitat’s resilience and ecological stability. This underpins the relevance of integrating past records in coastal wet dune slacks management in a scenario of constant adaptation processes.

scholarly journals Clonal selection of Eucalyptus grandis x Eucalyptus globulus for productivity, adaptability, and stability, using SNP markers

2016 ◽  
Vol 65 (2) ◽  
pp. 30-38 ◽  
Author(s):  
D. Torres-Dini ◽  
A. C. P. Nunes ◽  
A. Aguiar ◽  
N. Nikichuk ◽  
C. Centurión ◽  
...  
Keyword(s):  
Eucalyptus Globulus ◽  
Environmental Changes ◽  
Clonal Selection ◽  
Eucalyptus Grandis ◽  
Small Population ◽  
Snp Markers ◽  
Hybrid Population ◽  
Environment Interaction ◽  
Predictive Capacity ◽  
Selection Of

Abstract In Uruguay, reforestations with Eucalyptus sp. is of fundamental importance to supply paper, pulp, and wood production. This study investigates genetic, productivity, stability, and adaptability parameters in the selection of Eucalypts grandis x Eucalyptus globulus full-sib hybrid clones. The study was conducted in a clonal test, repeated in two different soils types, in Rio Negro State, Uruguay. The population was characterized phenotypically for diameter at breast height (dbh) and genotyped for SNP markers (EuCHIP60K chip). Mean dbh was similar between sites and the genotype–environment interaction was simple. We found high genotype correlation in clone performance between environments (0.708), indicating the possibility of selecting the same clones for both study locations. Mean heritability between clones (0.724), coefficient of individual genetic variation (10.9 %), and relative variation (0.916), suggest the possibility of gains (estimated at 3.1 % for both sites together) by selecting clones with higher growth rates. A total of 15,196 SNPs were used to confirm parentage and test a genomic selection model for dbh. The predictive capacity was negative (-0.15) given the small population size (78 individuals). The most adaptable material among the tested study sites presented higher values for SNP heterozygosity. Thus, using molecular markers to identify clones responsive to environmental changes can act as a powerful tool in Eucalyptus breeding programs. The hybrid population showed greater adaptability than E. globulus for this region.

scholarly journals High-resolution seismic reflection profiling: an aid for resolving the Pleistocene stratigraphy of a buried valley in central Illinois, USA

2013 ◽  
Vol 54 (64) ◽  
pp. 10-20 ◽  
Author(s):  
Andrew J. Stumpf ◽  
Ahmed Ismail
Keyword(s):  
High Resolution ◽  
Seismic Reflection ◽  
Pleistocene Glaciations ◽  
Glacial Sediments ◽  
Borehole Geophysics ◽  
Valley Fill ◽  
Sedimentary Sequences ◽  
Valley Fills ◽  
Central Illinois ◽  
Sand And Gravel

Abstract High-resolution seismic reflection (HRSR) data acquired over the Pesotum Bedrock Valley in central Illinois, USA, helped construct the seismic stratigraphy of a valley fill and the overlying sediments. Integrating these data with drilling and borehole geophysics allowed us to develop a seismo-stratigraphic classification for sediments on undulating and folded bedrock. Seven seismo-stratigraphic units that overlie the bedrock surface were characterized. Seismic units A and B include glacial sediments of multiple Pleistocene glaciations above the Pesotum Bedrock Valley, which completely mask the feature. Seismic units C–F, the valley fill, primarily include tills and glacial lake sediment deposited during the earliest Pleistocene glaciations and preglacial alluvium and colluvium that is draped over in situ weathered bedrock. The preservation of conformable-lying glacial and preglacial deposits and paucity of sand and gravel in the buried valley strongly indicate that little or no incision by glacial meltwaters has occurred. These observations contrast markedly with interpretations from buried valleys elsewhere in North America and northern Europe where valley fills contain significant deposits of sand and gravel in tunnel valleys. The HRSR data assisted the characterization and analysis of heterogeneous sedimentary sequences over a buried valley where existing subsurface information was limited. The extent of Pleistocene-age glacial lakes is inferred from the lateral continuity of silt and clay units.

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