Sedimentology

Neoproterozoic deglacial sediments and their hydrocarbon source rock potential

by Daniel Le Heron

Le Heron, D.P., Craig, J. (in press). In: Glaciogenic Reservoirs. Geological Society, London, Special Publications.

Considerable interest is awakening in Neoproterozoic petroleum systems, which represent a frontier research area in... more Considerable interest is awakening in Neoproterozoic petroleum systems, which represent a frontier research area in the Earth Sciences. Many strata deposited during the Cryogenian have a role to play in such petroleum systems, with viable source rocks and live oils, despite deposition before the evolution of most extant clades. Life forms likely to have contributed, in variable concentrations, to Neoproterozoic hydrocarbon source rocks include eukaryotic microalgae, bacteria, chlorophyte micoalgae, marine pelagophyte algae and dinoflagellates. The glaciations of a“Snowball” or “Slushball” Earth, or deposited under a “Zipper Rift” scenario, are believed to be intimately associated with the deposition of hydrocarbon source rocks. Deglaciation may have culminated in anoxic basins, with high TOC shales and “cap carbonates” deposited in depressions carved by ice sheets or alternatively deposited in restricted half graben a Rodinia began to fragment. One such example is the case of post-Sturt glaciation shales and dolostones in the Centralian Superbasin, an amalgam of basins almost continent-wide in Australia. In the southen part of this superbasin, data from the Marmot MMDD-1 drillcore (Stuart Shelf) together with published data on organic enrichment in the central part of the superbasin (Amadeus Basin), are used to infer the existance of a major organically-enriched mud blanket resulting from Sturtian deglaciation. 

Neoproterozoic-Devonian stratigraphic evolution of the eastern Murzuq Basin, Libya: a tale of tilting in the central Sahara

by Daniel Le Heron

Le Heron, D.P., Meinhold, G., Bergig, K. in press. basin Research, doi: 10.1111/j.1365-2117.2012.00555.x

The Murzuq Basin is one of the most petroliferous basins of North Africa. Its remote eastern flank, has been largely... more The Murzuq Basin is one of the most petroliferous basins of North Africa. Its remote eastern flank, has been largely ignored since early reconnaissance work in the 1950s and 1960s. This paper presents new stratigraphic and sedimentological data on the Neoproterozoic through Devonian succession from the Mourizidie and Dor el Gussa regions. The Neoproterozoic to Cambrian Mourizidie and Hasawnah formations in the eastern part of the Mourizidie dip to the east and north-east, resting directly on late Precambrian metasediments and granitoids. These strata record the initial progradation of sand-dominated braidplain systems upon peneplained Precambrian basement. Rhyolite clasts in the Hasawnah Formation may record tectonically driven uplift and unroofing in the southern Tibesti Massif or tectonomagmatic rejuvenation to the south of this massif. In the western part of the Mourizidie region, Late Ordovician through Silurian strata (Mamuniyat and Tanezzuft–Akakus formations) directly overlie late Precambrian metasediments and granitoids, and dip at a low angle toward the west into the Murzuq Basin. Elsewhere at the eastern Murzuq Basin flank, in Dor el Gussa, Late Ordovician glaciogenic sediments rest with angular unconformity upon shallow marine sandstones of Cambrian–Ordovician age. This angular unconformity may also occur in the Mourizidie region and indicates widespread tectonism, either as a result of a Middle–Late Ordovician orogenic event, far-field tectonism related to the opening of the Rheic Ocean along the northern margin of Gondwana, or alternatively crustal depression associated with the growth of Late Ordovician ice sheets. Unconformity development was also probably associated with glacial incision. Following ice sheet retreat, isostatic rebound during deglaciation resulted in uplift of tens to hundreds of metres, locally removing all Cambrian and Ordovician formations. Rising sea levels in the Silurian led to deposition of the Tanezzuft Formation on Precambrian basement in the northwestern Mourizidie region.

Basin-wide sediment trapping efficiency of emerging reservoirs along the Mekong

by Matti Kummu

I DEPOSITI DEL PLEISTOCENE INFERIORE DELLA BASSA VAL DI CECINA (TOSCANA, ITALIA): RICOSTRUZIONE STRATIGRAFICO–DEPOSIZIONALE E PROPOSTA DI SUDDIVISIONE IN UNITA’ ALLOSTRATIGRAFICHE

by Florence ReSeT

Giovanni Sarti, Andrea Ciampalini, Ilaria Consoloni & Andrea Cerrina Feroni

Fault array evolution in extensional basins: insights from statistical analysis of gravel deposits in the Cecina River (Tuscany, Italy)

by Florence ReSeT

Andrea Ciampalini, Ilaria Consoloni, Giovanni Sarti

Two statistical analyses of gravel clasts from the Lower Pleistocene deposits in the Lower Cecina Valley (Tuscany,... more Two statistical analyses of gravel clasts from the Lower Pleistocene deposits in the Lower Cecina Valley (Tuscany, Italy) have been combined to unravel changes in the palaeo-drainage system. Data from 16 outcrops were collected and 6400 clasts described. Facies analysis, micro-palaeontology and macro-palaeontology and petrographic characteristics of the gravel deposits have highlighted the presence of three allostratigraphic units. Clast lithology is the main discriminator among these units. Cluster and principal component analyses of the 6400 clasts have improved understanding of the stratigraphy of the Lower Pleistocene deposits and constrain the re-routing of the lower palaeo-Cecina River from a supposedly south-east to north-west direction to the present east to west direction. Short rivers feeding small fan deltas represented by the oldest allostratigraphic units were abandoned in the Lower Pleistocene, when the re-routing of the Cecina River caused the capture of these streams. This evolution suggests a change in the tectonic regime of the area. The fan deltas developed on the hanging wall of normal faults sub-parallel to the coast; a change to a transtensile tectonic regime caused the deviation of the main river channel toward the present coast and the formation of a pull-apart basin, which is now exploited by the Cecina River. This study illustrates the value of lithological analyses of gravel deposits for understanding the tectonic evolution of an area.

BURIAL DATING OF LATE-CENOZOIC DEPOSITS USING IN-SITU PRODUCED COSMOGENIC NUCLIDES

by Florence ReSeT

Andrea Ciampalini, Cristina Persano, Derek Fabel, Marco Firpo

Dating the Miocene to Pleistocene deposition of fluvial and deltaic sediments is often difficult because of the... more Dating the Miocene to Pleistocene deposition of fluvial and deltaic sediments is often difficult because of the absence of suitable biostratigraphic markers. Temporal limits on sediment deposition, however, are fundamental constraints in many geological, geomorphological, stratigraphical and archeological studies. In particular a dated stratigraphy of sedimentary basins provides information about timing of evolution of the sediment source and routing system due to tectonics, sea-level and/or climate changes. Traditional techniques, such as luminescence, radiocarbon dating of organic material, etc. only permit us to date sediments that are no older than ~250,000 years. Recently a method for dating sediment burial using the radioactive decay of cosmogenic nuclides 26Al and 10Be has been developed. 26Al and 10Be are produced by the continuous bombarding by high-energy cosmic rays of the Earth surface where they penetrate into rocks and sediments at a depth that varies, depending on rock density, between 2 and 3 m. The long half-life of the 26Al (7.05X105 yr) and 10Be (1.5X106 yr) make them optimal for dating sediments that were deposited over the past five million years, as long as the sediments were at the surface and exposed to cosmic rays before sedimentation and burial. The sediments that can be dated using the cosmogenic isotopes technique need to have the following characteristics: (1) quartz needs to be present and have been exposed at the surface for a time necessary to accumulate measurable cosmogenic radionuclides concentration (i.e., depending
on latitude and altitude, at least ~ 200 years); (2) transport time needs to have been negligible (3) burial was rapid and deep (>10 m) to avoid cosmogenic nuclides production after deposition, otherwise a correction needs to be introduced. This method is useful in many Italian areas where deltaic or fluvial Miocene to Pleistocene deposits crop out.

Holocene mass-wasting events in Lago Fagnano, Tierra del Fuego (54°S): Implications for paleoseismicity of the Magallanes-Fagnano transform fault

by Nicolas Waldmann

Basin Research, 23, 2, 171-190, 2011.

High-resolution seismic imaging and coring in Lago Fagnano, located along a plate boundary in Tierra del Fuego, have... more High-resolution seismic imaging and coring in Lago Fagnano, located along a plate boundary in Tierra del Fuego, have revealed a chronologic catalog of Holocene mass-wasting events. These structures are interpreted as sediment mobilizations resulting from gravity spreading induced by loading of the slope-adjacent lake floor during mass flow deposition. More than 22 mass flow deposits have been identified combining results from an 800 km-long dense grid of seismic profiles with sediment cores. Successions of up to 6 m thick mass flow deposits pond the basin floor spreading eastward and westward following the main axis of the eastern sub-basin of Lago Fagnano. An age model on the basis of information from previous studies and from new AMS-14C ages allowed establishing a well-constrained chronologic mass-wasting event catalogue covering the last ~15000 years. Simultaneously-triggered basin-wide lateral slope failure and the formation of multiple debris flow and megaturbidite deposits are interpreted as the fingerprint of paleo-seismic activity along the Magallanes-Fagnano transform fault that runs along the entire lake basin. The slope failures and megaturbidites are interpreted as recording large earthquakes occurring along the transform fault since the early Holocene. The results from this study provide new data about the frequency and possible magnitude of Holocene earthquakes in Tierra del Fuego, which can be applied in the context of seismic hazard assessment in southernmost Patagonia.

Marine geology of the Quaternary Bass Canyon system, southeast Australia: A cool-water carbonate system

by Stephen Gallagher

Fault array evolution in extensional basins: insights from statistical analysis of gravel deposits in the Cecina River (Tuscany, Italy)

by Ilaria Consoloni

ANDREA CIAMPALINI, ILARIA CONSOLONI, GIOVANNI SARTI. Sedimentolgy, 58, 1895-1913

Two statistical analyses of gravel clasts from the Lower Pleistocene deposits in the Lower Cecina Valley (Tuscany,... more Two statistical analyses of gravel clasts from the Lower Pleistocene deposits in the Lower Cecina Valley (Tuscany, Italy) have been combined to unravel changes in the palaeo-drainage system. Data from 16 outcrops were collected and 6400 clasts described. Facies analysis, micro-palaeontology and macro-palaeontology and petrographic characteristics of the gravel deposits have highlighted the presence of three allostratigraphic units. Clast lithology is the main discriminator among these units. Cluster and principal component analyses of the 6400 clasts have improved understanding of the stratigraphy of the Lower Pleistocene deposits and constrain the re-routing of the lower palaeo-Cecina River from a supposedly south-east to north-west direction to the present east to west direction. Short rivers feeding small fan deltas represented by the oldest allostratigraphic units were abandoned in the Lower Pleistocene, when the re-routing of the Cecina River caused the capture of these streams. This evolution suggests a change in the tectonic regime of the area. The fan deltas developed on the hanging wall of normal faults sub-parallel to the coast; a change to a transtensile tectonic regime caused the deviation of the main river channel toward the present coast and the formation of a pull-apart basin, which is now exploited by the Cecina River. This study illustrates the value of lithological analyses of gravel deposits for understanding the tectonic evolution of an area.

I DEPOSITI DEL PLEISTOCENE INFERIORE DELLA BASSA VAL DI CECINA (TOSCANA, ITALIA): RICOSTRUZIONE STRATIGRAFICO–DEPOSIZIONALE E PROPOSTA DI SUDDIVISIONE IN UNITA’ ALLOSTRATIGRAFICHE

by Ilaria Consoloni

Giovanni Sarti, Andrea Ciampalini, Ilaria Consoloni & Andrea Cerrina Feroni. Il Quaternario, 20, 151-162

ABSTRACT: G. Sarti et.al., Stratigraphic and depositional reconstruction of the Lower Pleistocene deposits from lower... more ABSTRACT: G. Sarti et.al., Stratigraphic and depositional reconstruction of the Lower Pleistocene deposits from lower Val di Cecina (Tuscany, Italy): a proposal of subdivision in Allostratigraphic Units. (IT ISSN 0394-3356, 2007).
In the area comprised between the villages of Riparbella and Casale Marittimo (lower Cecina Valley, Tuscany, Italy) a large amount of Pleistocene deposits outcrops. Through a detailed geological survey integrated with facies analysis five litostratigraphic units, grouped in three Allostratigraphic Units (UA), have been detected. The oldest (UA7), lower pleistocenic in age, is formed by two litostratigraphic units (“Conglomerati delle Ginepraie” and “Sabbie ed argille ad Arctica islandica”) showing latero-vertical relationships and are organized
in a transgressive-regressive cycle. The “Conglomerati delle Ginepraie” are arranged in a fining upwards trend and were deposited in small coalescent deltaic environments. Three depositional facies are recognized within the “Sabbie ed argille ad Arctica islandica” recording a fining-coarsening and deepening shallowing upward trend. The UA7 lies in unconformity above pre-quaternary deposits.
The second (UA6), lower pleistocenic in age, is also constituted by two heteropic and transgressive litostratigraphic units
(“Conglomerati delle Lame” and “Arenarie e Sabbie di Montescudaio”) lying in angular unconformity on the UA7. The “Conglomerati delle Lame”, showing a well developed imbrication, were deposited in a foreshore to upper shoreface depositional environment. The “Arenarie e Sabbie di Montescudaio” are characterized by a high to low planar-cross stratification and sometimes by overturned stratification
and were deposited in a shallow marine environment. The regressive phase of this UA is not preserved due to erosive processes. The youngest unit (UA4, “Conglomerati di Serra all’Olio”), was instead deposited in fluvial-braided environment and lies in angular unconformity on the others UA. The middle pleistocenic age of this unit has been inferred on the basis of its stratigraphic position. This stratigraphic reconstruction strongly conflict from previous interpretations. Important climatic and geological remarks derive from the finding of two taxa (Arctica islandica and the coral Cladocora caespitosa) at different stratigraphic positions within the oldest unit (“Sabbie ed argille ad Arctica islandica”). The Arctica islandica testifying cold temperatures (4°C to 13°C) characterizes the first 5
meters of the unit, while beds of Cladocora caespitosa (15°C to 22°C the temperature range of this coral) only occur upwards. We
retain that the deposition of the “Sabbie ed argille ad Arctica islandica” takes place during a warming phase and that the development of Cladocora caespitosa beds could be related to the maximum flooding conditions at the end of the transgressive phase. This interpretation leads to some notable chronostratigraphic implications.

The Paks loess-paleosol sequence: A record of chemical weathering and provenance for the last 800 ka in the mid-Carpathian Basin

by János Kovács

Újvári et al.  published in 'Quaternary International'

The Paks loess-paleosol sequence is one of the most important terrestrial records of Middle and Late Pleistocene... more The Paks loess-paleosol sequence is one of the most important terrestrial records of Middle and Late Pleistocene environmental changes in East Central Europe, spanning the last ca. 0.8 Ma. While geochemical proxies demonstrate a general decreasing chemical weathering trend over the last 0.8 Ma in the Carpathian Basin, mineralogy and derived indices reflect intensifying physical erosion. In theory, the observed chemical weathering trend can be accounted for both by enhanced input of relatively unweathered material and by climate deterioration during the Quaternary, as the proxies such as CIA are not capable of distinguishing between pre- and post-depositional weathering. Enhanced physical erosion of the source areas, driven by tectonism, and resulting increased sedimentation of fresh mineral dust at the depositional site are demonstrated by increasing dolomite, illite and chlorite contents and sme/ill, sme/(ill+chl) ratios from older to younger sediments in the profile, together with increasing thickness of loess layers towards the youngest part of the sequence. At the same time, constant smectite contents (30-40%) in paleosols appear to disprove progressive aridization of interglacials through time and suggest that the duration of pedogenesis played an important role in determining soil types. Further, the increasing proportion of inherited phyllosilicates (illite and chlorite) would, in theory, raise the possibility that the decreasing values of chemical weathering indices are just artifacts of enhanced physical erosion and resulting increased dust deposition by a dilution effect. The above findings highlight the fact that the general view on chemical weathering is oversimplistic, as its ’equation’ includes two basic variables, tectonism and time beyond climate and the interplay of these equally important factors will eventually determine its final value. To get a better grasp of these processes needs further data (more age control in loess profiles, data on uplift in and around sedimentary basins) and more sophisticated proxies, as the mineralogical data presented here can be considered only semi-quantitative.

Regarding the provenance of sediments in the Paks profile, geochemical data demonstrate that felsic rocks dominated the source areas and there have been only very little variations in provenance over the last ca. 0.8 Ma. Significant contributions from mafic/ultramafic rocks to the sediments can be ruled out as revealed by lower abundances of ferromagnesian trace elements. The appearance of amphiboles and high dolomite contents suggest that loess material was at least partly sourced from local rocks and geochemical data reveal a genetic link between floodplain sediments and loess deposits.

Fluvial response to an historic lowstand of the Great Salt Lake, Utah

by Kathleen Nicoll

--> Citation : Krysia Skorko, Paul W. Jewell and Kathleen Nicoll. in press 2011. Fluvial Response to an Historic Low Stand of the Great Salt Lake, Utah. Earth Surface Processes and Landforms 37:143-156. doi: 10.1002/esp.2226

ABSTRACT Understanding fluvial adjustments to base level changes benefits the fields of sequence stratigraphy,... more ABSTRACT Understanding fluvial adjustments to base level changes benefits the fields of sequence stratigraphy, geomorphology and petroleum geology. This investigation is a modern case study of the channel dynamics of Lee Creek and the Goggin Drain, two streams that are part of the Jordan River drainage into the endorheic Great Salt Lake of northern Utah, a lacustrine system that has experienced multiple, decadal-scale base level changes. Since 1965, the lake level has fluctuated in elevation more than 6 m, transitioning from an historic lowstand [< 1279 m above sea level (a.s.l.)] to an historic highstand (>1284 m a.s.l.), and in 2009–2010 approaching an historic lowstand. This study uses detailed aerial images, fieldwork and LiDAR data to link the modern geomorphology and channel hydraulics to specific variations in sediment transport, channel form, and avulsion behavior. Although Lee Creek and the Goggin Drain are situated only a few kilometers apart and share similar shore zone gradients, substrates and vegetation patterns, and have been subjected to the same changes in lake level, their channel forms have evolved very differently. Differences in discharge patterns are likely the most influential factor causing the meandering form of Lee Creek and the braiding channel of the Goggin Drain. Despite the differences in discharge, total sediment eroded from the two streams is comparable and can be attributed to similar stream power/unit stream width in the two streams. Although Lee Creek has not recently been avulsive, three major avulsions of the Goggin Drain have taken place since 1965. Two possible styles of avulsion are interpreted: an allogenic response to changing base level, and an autogenic response dictated by channel morphology and hydraulics. Despite a wealth of available information, avulsions cannot be unequivocally attributed to one style or another. Caution should be used when attempting to link the complex process of avulsion to causal mechanisms.

Fault array evolution in extensional basins: insights from statistical analysis of gravel deposits in the Cecina River (Tuscany, Italy)

by Andrea Ciampalini

A. CIAMPALINI, I. CONSOLONI, G. SARTI, Sedimentology 58, Issue 7, pages 1895–1913, 2011

Two statistical analyses of gravel clasts from the Lower Pleistocene deposits in the Lower Cecina Valley (Tuscany,... more Two statistical analyses of gravel clasts from the Lower Pleistocene deposits in the Lower Cecina Valley (Tuscany, Italy) have been combined to unravel changes in the palaeo-drainage system. Data from 16 outcrops were collected and 6400 clasts described. Facies analysis, micro-palaeontology and macro-palaeontology and petrographic characteristics of the gravel deposits have highlighted the presence of three allostratigraphic units. Clast lithology is the main discriminator among these units. Cluster and principal component analyses of the 6400 clasts have improved understanding of the stratigraphy of the Lower Pleistocene deposits and constrain the re-routing of the lower palaeo-Cecina River from a supposedly south-east to north-west direction to the present east to west direction. Short rivers feeding small fan deltas represented by the oldest allostratigraphic units were abandoned in the Lower Pleistocene, when the re-routing of the Cecina River caused the capture of these streams. This evolution suggests a change in the tectonic regime of the area. The fan deltas developed on the hanging wall of normal faults sub-parallel to the coast; a change to a transtensile tectonic regime caused the deviation of the main river channel toward the present coast and the formation of a pull-apart basin, which is now exploited by the Cecina River. This study illustrates the value of lithological analyses of gravel deposits for understanding the tectonic evolution of an area.

I DEPOSITI DEL PLEISTOCENE INFERIORE DELLA BASSA VAL DI CECINA (TOSCANA, ITALIA): RICOSTRUZIONE STRATIGRAFICO–DEPOSIZIONALE E PROPOSTA DI SUDDIVISIONE IN UNITA’ ALLOSTRATIGRAFICHE

by Andrea Ciampalini

G. Sarti, A. Ciampalini, I. Consoloni & A. Cerrina Feroni - Il Quaternario, Italian Journal of Quaternary Sciences
20(2), 2007 - 151-162

In the area comprised between the villages of Riparbella and Casale Marittimo (lower Cecina Valley, Tuscany, Italy) a... more In the area comprised between the villages of Riparbella and Casale Marittimo (lower Cecina Valley, Tuscany, Italy) a large amount of Pleistocene deposits outcrops. Through a detailed geological survey integrated with facies analysis five litostratigraphic units, grouped in three Allostratigraphic Units (UA), have been detected. The oldest (UA7), lower pleistocenic in age, is formed by two litostratigraphic units (“Conglomerati delle Ginepraie” and “Sabbie ed argille ad Arctica islandica”) showing latero-vertical relationships and are organized in a transgressive-regressive cycle. The “Conglomerati delle Ginepraie” are arranged in a fining upwards trend and were deposited in small coalescent deltaic environments. Three depositional facies are recognized within the “Sabbie ed argille ad Arctica islandica” recording a fining-coarsening and deepening shallowing upward trend. The UA7 lies in unconformity above pre-quaternary deposits.
The second (UA6), lower pleistocenic in age, is also constituted by two heteropic and transgressive litostratigraphic units
(“Conglomerati delle Lame” and “Arenarie e Sabbie di Montescudaio”) lying in angular unconformity on the UA7. The “Conglomerati delle Lame”, showing a well developed imbrication, were deposited in a foreshore to upper shoreface depositional environment. The “Arenarie e Sabbie di Montescudaio” are characterized by a high to low planar-cross stratification and sometimes by overturned stratification
and were deposited in a shallow marine environment. The regressive phase of this UA is not preserved due to erosive processes. The youngest unit (UA4, “Conglomerati di Serra all’Olio”), was instead deposited in fluvial-braided environment and lies in angular unconformity on the others UA. The middle pleistocenic age of this unit has been inferred on the basis of its stratigraphic position. This stratigraphic reconstruction strongly conflict from previous interpretations. Important climatic and geological remarks derive from the finding of two taxa (Arctica islandica and the coral Cladocora caespitosa) at different stratigraphic positions within the oldest unit (“Sabbie ed argille ad Arctica islandica”). The Arctica islandica testifying cold temperatures (4°C to 13°C) characterizes the first 5 meters of the unit, while beds of Cladocora caespitosa (15°C to 22°C the temperature range of this coral) only occur upwards. We
retain that the deposition of the “Sabbie ed argille ad Arctica islandica” takes place during a warming phase and that the development of Cladocora caespitosa beds could be related to the maximum flooding conditions at the end of the transgressive phase. This interpretation leads to some notable chronostratigraphic implications.

Dynamique d'occupation anthropique et dynamique alluviale du Rhin au cours de l'Holocène: géoarchéologie du site d'Oedenburg (Haut-Rhin, France)

by Vincent Ollive

Human settlement dynamics and alluvial dynamics of the Rhine River during the Holocene: Geoarchaeology of the site of Oedenburg (Haut-Rhin, France).

Author: V. Ollive
PhD Thesis in Earth Sciences, University of Dijon (2007). 305p.
Thèse de Doctorat de Sciences de la Terre, Université de Dijon. 305p.

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A segment of the Upper Rhine River presenting both anastomosed and braided was investigated. This area gives us the... more A segment of the Upper Rhine River presenting both anastomosed and braided was investigated. This area gives us the opportunity to study settlement dynamics during two key periods of the Holocene. The Roman Period characterised by a first major anthropogenic impact on the environment and poorly documented climatic changes. The Little Ice Age, when human settlement and climate may be well documented with high reliability.
A wide methodological approach has been completed to combine results from geomorphology, stratigraphy, geophysics, G.I.S., palynology, dendrochronology and archaeology. This dataset shows:
1/ documentary flood frequency variations of the Rhine River during the last 800 years. These chronological variations show some dissimilarity with other French rivers reconstructed documentary flood series. That attests a primary control of catchment’s characteristics and regime type on long term hydrological dynamics.
2/ changes in the Rhine River and floodplain dynamics during Little Ice Age before major anthropogenic river management of 19th century. Planform changes, riverine forest, land use evolution, and anthropological settlement processes are described and quantified. These results allow the identification of major stratigraphic agent factors role responsible of these changes.
3/ the alluvial landscape character where the Oedenburg site settled, together with the evolution of the riverine forest influenced by the Rhine River hydrodynamics.
4/ settlement dynamics during Antiquity. Four major settlement phases have been evidenced by spatial distribution analysis of roman coins found by pedestrian prospecting during the last twenty years. Settlement dynamics may have been influenced by either historical or environmental impacts.
5/ variations in alluvial dynamics of the Rhine River during Antiquity such as high water table or flooding events.

Water and sediment movements in Harbours

by Roger Falconer - Cardiff University

Paper 54: Yin, J., Falconer, R. A., Chen, Y. P. and Probert, S. D. 2000. Water and sediment movements in Harbours. Applied Energy. 67(3), 341-352.

Abstract
Water movements in five harbour-models were assessed using (i) a Sontek-ADV to measure the velocity... more Abstract
Water movements in five harbour-models were assessed using (i) a Sontek-ADV to measure the velocity distributions and (ii) fluorometers to determine the local solute-concentrations under both tidal and steady flows. The width of the harbour entrance and the water-depth's amplitude influence significantly the flushing process for the narrow-entrance harbours. To achieve a high rate of flushing, as required in harbours in order to reduce the pollution concentration therein and the need for dredging, it is recommended that as wide as is feasible entry into the harbour is used: if a separate entry and exit are to be introduced, they should be well separated. Less expenditures of commercially-purchased energy will then be required for achieving these aims.

The Pleistocene of Schöningen, Germany: a complex tunnel valley fill revealed from 3D subsurface modelling and shear wave seismics

by Jörg Lang

Lang, J., Winsemann, J. Steinmetz, D., Polom, U., Pollok, L., Böhner, U., Serangeli, J., Brandes, C., Hampel, A. & Winghart, S. (2012) Quaternary Science Reviews, 39, 86-105.

The Pleistocene deposits of Schöningen represent an outstanding geological and archaeological archive, where an up to... more The Pleistocene deposits of Schöningen represent an outstanding geological and archaeological archive, where an up to 45 m thick Middle to Late Pleistocene succession has been preserved and unique artefacts from the Lower Palaeolithic have been discovered. The preservation of such a thick and complete glacial/interglacial succession is very rare in the geological record and requires a specific depositional setting. We will present a new depositional model for the Pleistocene succession of Schöningen, integrating outcrop data, borehole data and high-resolution shear wave seismics. A total of four outcrop sections and 744 borehole logs were examined to document the complex facies architecture. All collected sedimen-tological and geophysical data sets were integrated into a high-resolution 3D geological model (GOCAD®) for reconstructing the spatial distribution of facies associations and the large-scale depositional architecture. The spatial distribution of the artefacts will be discussed with respect to the depositional environment.
The Elsterian and Holsteinian deposits are restricted to a NNW-SSE trending, elongated trough, which is deeply incised into unconsolidated lignite-bearing Palaeogene deposits. The geometry of this erosional structure points to a tunnel valley origin that was incised below the Elsterian ice sheet. The basal tunnel valley fill consists of cross-stratified pebbly sand and gravel overlain by till. After deglaciation the tunnel valley remained underfilled and acted as a depocentre for interglacial deposition. During the subsequent Holsteinian interglacial (MIS 9) a lake formed within this depocentre and lacustrine sediments accumulated. This interglacial succession consists of peat, organic-rich silt and fine-grained sand interpreted as lake-bottom and deltaic sediments fed by surface run-off shed from the Elm ridge. The lacustrine deposition was controlled by repeated lake-level fluctuations in the range of 1 to 6 metres leading to the formation of laterally stacked delta systems. These lake-level changes were probably triggered by climate, causing variations of precipitation and surface run-off. During the late Saalian glaciation the remnant tunnel valley was completely filled with meltwater deposits. The sedimentary facies and depositional architecture point to a shallow-water delta. Subsequently the meltwater deposits were overlain by till.
The deposition of the Middle Pleistocene sediments within an Elsterian tunnel valley explains the unique preservation of the sedimentary succession of Schöningen. The long-lived inter-glacial lake provided an attractive site for animals and early humans ambushing them. Arte-facts mainly became embedded on the delta plain, which rapidly was transgressed during lake-level rise and artefacts were thus preserved.

Separation and Measurement of Pa, Th, and U Isotopes in Marine Sediments by Microwave-Assisted Digestion and Multiple Collector Inductively Coupled Plasma …

by Alex Thomas

Mapping of the Holocene Rhine-Meuse delta - The 'Berendsen Map'

by Kim Cohen

Esther Stouthamer, Wim Hoek, Kim Cohen (2012) Mapping of the Holocene Rhine-Meuse delta - The 'Berendsen Map'. In.: Floor (coord. ed.) Dutch Earth Sciences - development and impact, The Hague, KNGMG, p. 176.

A map figure covering the full delta, supplemented with a historic overview of the displayed mapping, and a figure... more A map figure covering the full delta, supplemented with a historic overview of the displayed mapping, and a figure caption highlighting the main features of the delta, illustrated with the map and outcome of a long series of PhD thesises from our group, serving as an example of progress in delta mapping in the 100 years of existence of the Royal Netherlands' Society for Geology and Mining (KNGMG). The rest of this abstract is the figure caption (K.M. Cohen, 2011).

Distribution, Age-of-Abandonment and Network Evolution of Fluvial Channel Belts in the Rhine-Meuse delta (Holocene, The Netherlands. Mapping based on ca. 250.000 shallow boreholes collected since 1950. Dating based on ca. 1500 14C dates on fluvial depositional elements and >30.000 catalogued archeological finds, in known stratigraphical context. Background topography from laser altimetry (www.ahn.nl). Delta network queried from the Utrecht Rhine-Meuse Delta Studies' GIS system for delta palaeogeography reconstruction, originally developed for Berendsen & Stouthamer (2000, 2001) Stouthamer (2001): see Berendsen, Cohen, Stouthamer (2007). Updated 2003, 2007, 2011 (Cohen, 2003; Gouw, 2007, 2008; Erkens, 2009; Bos, 2010; Stouthamer et al., 2011).

Feature description: (i) Delta is bound by Pleistocene ice-marginal topography, including terminal ice-pushed ridges of the Saalian Drenthe Substage maximum limit, ca. 150,000 years ago. (ii) Delta is protected by the Middle-Late Holocene Holland coastal barrier system. (iii) major 19th and 20th cy reclamations in the central Netherlands' lagoon and works at the Amsterdam and Rotterdam harbours bound the modern delta. Diggings, embankments and reclamations in the delta plain go back to Medieval times, starting 1000 years ago. The southwest of the delta is an estuary network resulting form Medieval storm surge ingressions into early reclaimed lands, and human response hereto. (iv) In the central delta, the Rhine is joined by its tributary the Meuse. The rivers share estuaries and tidal river reaches in the delta. (v) Middle Holocene deltaic channel belt avulsions occurred, during and following transgression that made the delta form at its present position. Despite avulsions, however, the trunk channel system remained in position at the Northern edge of the pre-transgression valley: only minor Rhine branches were active to the south, and trunk channel avulsions were always northward. (vi) A major avulsive network reorganisation occured in the Late Holocene, commencing in the last millenium BC, a marked trend break with the five millenia of delta evolution before.The reorganisation was triggered in the upper part of the delta, as a response to increased loads of fine sediment, delivered from the prehistoric deforested hinterland. New northward distributaries avulsed and found the central Netherlands' lagoon. New southwestward distributaries avulsed and found the Meuse estuary, and gradually became the major branches. This culminated in abandonment of the former Rhine trunk channel and its northerly outlet at the time human embankments began (11th cy AD). (vii) The network reorganization, initiated at the upstream side of the delta, at the downstream end caused the abandonment of the matured Leiden outlet, where the river had long injected sediment into the open North Sea. It replaced this outlet with a mouth into Rotterdam estuary, which trapped more and more Rhine bed load, as the avulsed branch gained importance. At the beginning of the first millenium AD, this triggered major coastal reorganisation along the Zeeland-Holland coastal barrier system, further helped by the additional accommodation created by auto-compaction that occured where clay buried peats and by storm surges that eroded reclaimed peat land and created new estuaries and new inshore trapping space for Rhine-Meuse sediments.

Toarcian black shales in the Dutch Central Graben: record of energetic variable depositional conditions during an oceanic anoxic event

by João Trabucho-Alexandre

published in 'Journal of Sedimentary Research', 2012

The environmental conditions, mechanisms, and processes that resulted in the deposition of organic-matter-rich... more The environmental conditions, mechanisms, and processes that resulted in the deposition of organic-matter-rich sediments during the early Toarcian oceanic anoxic event are still a matter of discussion. A petrographic and geochemical study was carried out using Posidonia Shale Formation (lower Toarcian) black shale samples from two wells located offshore The Netherlands in the Dutch Central Graben. This formation is a lateral equivalent of Toarcian black shale successions in northern Europe. The lower Toarcian black shales in the Dutch Central Graben exhibit a variety of depositional fabrics, sedimentary structures, and textures that indicate dynamic energetic conditions at the time of their deposition and appear to have been deposited mostly by bottom currents rather than settling from pelagic suspension. The Posidonia Shale Formation black shales are characterized by normally graded thin beds (, 10 mm thick) with erosional bases wherein cross-lamination is very common. The tops of these thin beds are commonly bioturbated. These observations are in contrast with the traditional interpretation of the deposition of lower Toarcian black shales as having taken place under a stagnant, anoxic water column via suspension settling. Black shales are commonly more heterogeneous than normally assumed and are the product of diverse sedimentary processes. Geochemical results, in combination with petrography, suggest that productivity and high accumulation rates of reactive organic matter were behind the establishment of sediment anoxia. The most organic-matter-rich shales, which are characterized by redox-element anomalies, are cross-laminated, thin-bedded shales, and each thin bed was deposited quickly, thus favoring the preservation of organic matter. The petrographic study of black shales complements geochemical data because geochemical analysis of sedimentary rocks, however high-resolution, always represents an averaging of environmental conditions at the time of deposition over at least several hundreds of years.