The New Jersey margin scientific drillig project (IODP Expedition 313): Unstangling the record of global and local sea-level changes

the Expedition 313 Science PartyInternational audienceMuch of the world is currently experiencing shorelineretreat due to global sea level rising at the rate of 3–4 mm yr -1.This rate will likely increase and result in a net rise to roughly1 m above present sea-level by the year 2100 (e.g., Rahmstorf,2007; Solomon et al., 2007), with significant consequencesfor coastal populations, infrastructures, and ecosystems.Preparing for this future scenario calls for careful study ofpast changes in sea level and a solid understanding ofprocesses that govern the shoreline response to thesechanges. One of the best ways to assemble this knowledge isto examine the geologic records of previous global sea-levelchanges. Integrated Ocean Drilling Program (IODP)Expedition 313 set out to do this by recovering a record ofglobal and local sea-level change in sediments depositedalong the coast of eastern North America during the Icehouseworld of the past 35 m.y. What we learn from this record—thefactors driving sea-level changes, and the impact of thischange on nearshore environments—will help us understandwhat lies ahead in a warming world

Submarine paleoseismology of the northern Hikurangi subduction margin of New Zealand as deduced from Turbidite record since 16 ka

International audiencePaleoseismic studies seek to characterise the signature of pre-historical earthquakes by deriving quantitative information from the geological record such as the source, magnitude and recurrence of moderate to large earthquakes. In this study, we provide a w16,000 yr-long paleo-earthquake record of the 200 km-long northern Hikurangi Margin, New Zealand, using cm-thick deep-sea turbidites identified in sediment cores. Cores were collected in strategic locations across the margin within three distinct morphological re-entrants e the Poverty, Ruatoria and Matakaoa re-entrants. The turbidite facies vary from muddy to sandy with evidence for rare hyperpycnites interbedded with hemipelagites and tephra. We use the Oxal probabilistic software to model the age of each turbidite, using the sedimentation rate of hemipelagite deduced from well-dated tephra layers and radiocarbon ages measurements on planktonic foraminifera. Turbidites are correlated from one core to the other using similarity in sedimentary facies, petrophysical properties and ages. Results show that 46 turbidites are synchronous along the entire margin. Amongst them 41 are interpreted as originating from the upper continental slope in response to earthquake-triggered slope failures between 390 170 to 16,450 310 yr BP. Using well-established empirical relationships that combine peak ground acceleration, magnitude and location of earthquakes, we calculate that synchronous slope failures were triggered by the rupture of 3 of the 26 known active faults in the region, each capable of generating Mw 7.3 to 8.4 earthquakes e two are crustal reverse faults and one is the subduction interface. The 41 Mw 7.3 earthquakes occurred at an average recurrence interval of w400 yr over the last w16,000 yr. Among them, twenty are interpreted as subduction interface earthquakes that occurred at an average recurrence interval of w800 yr, with alternating periods of high activity and low return times (305e610 yr) and quiescence periods with high return times (1480e2650 yr). Based on turbidite paleoseismology, we propose that subduction interface earthquakes were of lower magnitude during active periods (Mw > 7.5) than during quiescence periods (Mw 8.2)

Building an 18 000-year-long paleo-earthquake record from detailed deep-sea turbidite characterisation in Poverty Bay, New Zealand

In :" Marine and lake paleoseismology" Special Issue. Editor(s) : D. Pantosti, E. Gràcia, G. Lamarche, and H. NelsonInternational audienceTwo 20 m-long sedimentary cores collected in two neighbouring mid-slope basins of the Paritu Turbidite System in Poverty Bay, east of New Zealand, show a high concentration of turbidites (5 to 6 turbidites per meter), interlaid with hemipelagites, tephras and a few debrites. Turbidites occur as both stacked and single, and exhibit a range of facies from muddy to sandy turbidites. The age of each turbidite is estimated using the statistical approach developed in the OxCal software from an exceptionally dense set of tephrochronology and radiocarbon ages ( 1 age per meter). The age, together with the facies and the petrophysical properties of the sediment (density, magnetic susceptibility and Pwave velocity), allows the correlation of turbidites across the continental slope (1400-2300m water depth). We identify 73 synchronous turbidites, named basin events, across the two cores between 819±191 and 17 729±701 yr BP. Compositional, foraminiferal and geochemical signatures of the turbidites are used to characterise the source area of the sediment, the origin of the turbidity currents, and their triggering mechanism. Sixty-seven basin events are interpreted as originated from slope failures on the upper continental slope in water depth ranging from 150 to 1200 m. Their earthquake trigger is inferred from the heavily gullied morphology of the source area and the water depth at which slope failures originated. We derive an earthquake mean return time of 230 yr, with a 90% probability range from 10 to 570 yr. The earthquake chronology indicates cycles of progressive decrease of earthquake return times from 400 yr to 150 yr at 0- 7 kyr, 8.2-13.5 kyr, 14.7-18 kyr. The two 1.2 kyr-long intervals in between (7-8.2 kyr and 13.5-14.7 kyr) correspond to basin-wide reorganisations with anomalous turbidite deposition (finer deposits and/or non deposition) reflecting the emplacement of two large mass transport deposits much more voluminous than the "classical" earthquake-triggered turbidites. Our results show that the progressive characterisation of a turbidite record from a single sedimentary system can provide a continuous paleo-earthquake history in regions of short historical record and incomplete onland paleoearthquake evidences. The systematic description of each turbidite enables us to infer the triggering mechanism

Long-term slip rates and fault interactions under low contractional strain, Wanganui Basin, New Zealand

The newly mapped Kapiti-Manawatu Fault System (KMFS) in southern North Island, New Zealand, accommodated ∼3.5 km of basement throw over the last 3 Myr. Along-strike throw profiles are generated using seven stratigraphic markers, interpreted from seismic reflection profiles acquired <3 km apart. The profiles are symmetrical about their point of maximum displacement, and cumulative profiles suggest that the reverse fault system behaves coherently. The KMFS originates from the reactivation of extensional structures, with fault lengths remaining constant over time. Contractional deformation started at circa 1750 ± 400 ka. Maximum dip-slip rates along individual faults are 1.77 ± 0.53 and 0.74 ± 0.22 mm yr−1 for the 0–120 and 120–1350 ka periods, respectively. The maximum cumulative throw rates across the KMFS are 4.9 ± 1.5 and 1.5 ± 0.5 mm yr−1 for the same periods. Long-term strain rates across the KMFS are 2–5 times smaller than strain rates in the forearc basin of the Hikurangi subduction margin located less than 100 km to the east. The faults of the KMFS may extend to depth and link with the subducted Pacific plate

Inner forearc sequence architecture in response to climatic and tectonic forcing since 150 ka : Hawhe's Bay, New Zealand

International audienceThe influence of eustasy, tectonic deformation, and sediment flux as controlling parameters on basin stratigraphy and depositional sequence development are largely accepted. Eustasy is usually considered as the dominant mechanism of sequence generation, especially for Pleistocene successions. In active subduction-margin settings, the high rates of tectonic deformation are expected to have a stronger influence on basin-fill architecture, while sediment flux is generally less well constrained, and therefore less frequently considered. The active Hikurangi subduction margin in New Zealand offers the opportunity to quantitatively assess the relative roles of tectonic, climatic, and eustatic drivers. We present a quantitative source-to-sink-like study of the late Pleistocene succession from the Hawke's Bay sector of the inner forearc domain (c. 150 ka to present). The interpretation of a grid of high-resolution marine seismic data, onland and offshore core and well descriptions, and the integration of geomorphic studies enabled identification of system tracts. In turn these comprise two sea-level-cycle depositional sequences (LPS1 and LPS2), including one complete 100 ka sequence (LPS1). Isopach maps of both sequences reveal changes in sediment distribution and preservation that reflect the relative roles of tectonic deformation and eustasy. Eustasy dominates development of sequence architecture at relatively short time scales (i.e., 100 kyrs). Four long-lasting depocenters are identified over the inner forearc domain and located in four subsiding basins (Kidnappers, Mahia, Lachlan, and Motu-o-Kura basins). Significant shifts of the depocenter location in the basins are correlated with eustatic sea-level changes. Estimates of sediment volumes and masses from isopach maps indicate higher mass accumulation rates during climato-eustatic extremes, which we correlated to the onland erosional response. Sediment distribution and landscape evolution are strongly influenced by the interaction of the structural deformation and sediment flux. We present paleogeographic reconstructions for the inner forearc domain coincident with two paleoclimatic extremes (Last Glacial Maximum and Holocene Optimum). These illustrate the importance of eustatic changes, structural deformation, and sediment flux on the pattern of sediment distribution, accumulation, and sequence architecture

Distinguishing Natural Evolution and Human Impact on Estuarine Morpho-sedimentary Development: A Case Study from the Vilaine Estuary, France

International audienceEstuaries are coastal areas controlled by hydrodynamic factors such as sea-level changes, waves and tidal currents, and river discharge. This study focuses on the Vilaine Estuary which is strongly impacted by human activity after construction of Arzal dam in 1970. The purpose of this research is to differentiate the role of natural from anthropogenic factors on sediment dynamics within the Vilaine Estuary. We are proposing a hypothetical model based on the hydrodynamic modification and morpho-sedimentary development by analyzing the natural estuarine evolution and the impact of human alteration to the natural system by utilizing datasets including river discharge, tidal currents, winds and wave activities to further combine with photographic, bathymetric, topographic and sedimentary surveys. Results show that waves carry sediment from the sea and rework local sediments. The river damming is reducing the tidal prims and leads to the fall of tidal currents. This new situation supports the sediment deposition and reduces at the same time the accommodation space which decrease tidal currents in feed-back. The Vilaine Estuary is therefore coming close to a bay-type functioning which leads to a channel narrowing, a drastic increase of the tidal flat zone, an acceleration of erosional processes affecting the main channel, salt marsh and all associated depositional systems. We propose a hypothetical model showing that this evolution took place in two steps and we show that the dam has an effect to accelerate a natural infilling of the estuary

Incised-valley morphologies and sedimentary-fills within the inner shelf of the northern Bay of Biscay

This study is a first synthesis focused on incised-valleys located within the inner shelf of the Bay of Biscay. It is based on previously published results obtained during recent seismic surveys and coring campaigns. The morphology of the valleys appears to be strongly controlled by tectonics and lithology. The Pleistocene sedimentary cover of the shelf is very thin and discontinuous with a maximum thickness ranging between 30 and 40 m in incised-valley fills. Thus the incised bedrock morphology plays a key-role by controlling hydrodynamics and related sediment transport and deposition that explains some variations of those incised-valley fills with respect to the previously published general models

Postglacial (after 18 ka) deep-sea sedimentation along the Hikurangi subduction margin (New Zealand): Characterisation, timing and origin of turbidites

International audienceRecent sedimentation along the Hikurangi subduction margin off northeastern New Zealand is investigated using a series of piston cores collected between 2003 and 2008. The active Hikurangi Margin lies along the Pacific-Australia subduction plate boundary and contains a diverse range of geomorphologic settings. Slope basin stratigraphy is thick and complex, resulting from sustained high rates of sedimentation from adjacent muddy rivers throughout the Quaternary. Turbidites deposited since c. 18 ka in the Poverty, Ruatoria and Matakaoa re-entrants are central to this study in that they provide a detailed record of the past climatic conditions and tectonic activity. Here, alternating hemipelagite, turbidite, debrite and tephra layers reflect distinctive depositional modes of marine sedimentation, turbidity current, debris flow and volcanic eruption, respectively. Turbidites dominate the record, ranging in lithofacies from muddy to sandy turbidites, and include some basal-reverse graded turbidites inferred to be derived from hyperpycnal flows. Stacked turbidites are common and indicate multiple gravity-flows over short time periods. The chronology of turbidites is determined by collating an extremely dense set of radiocarbon ages and dated tephra, which facilitate sedimentation rate calculation and identification of the origin of turbidites. Sedimentation rates range from 285 cm/ka during late glacial time (18.5-17 ka) to 15 to 109 cm/ka during postglacial time (17-0 ka). Turbidite deposition is controlled by: (1) the emplacement of slope avalanches reorganising sediment pathways; (2) the postglacial marine transgression leading to a five-fold reduction in sediment supply to the slope due to disconnection of river mouths from the shelf edge, and (3) the Holocene/ Pleistocene boundary climate warming resulting in a drastic decrease in the average turbidite grain-size. Flood-induced turbidites are scarce: nine hyperpycnites are recognised since 18 ka and the youngest is correlated to the largest ENSO-related storm event recorded onland (Lake Tutira). Other turbidites contain a benthic foraminiferal assemblage which is strictly reworked from the upper slope and which relates to large earthquakes over the last c. 7 ka. They yield a shorter return time (270-430 years) than the published coastal records for large earthquakes (c. 670 years), but the offshore record is likely to be more complete. The deep-sea sedimentation along the New Zealand active margin illustrates the complex interaction of tectonic and climate in turbidite generation. Climate warming and glacio-eustatic fluctuations are well recorded at a millennial timescale (18 ka), while tectonic deformation and earthquakes appear predominant in fostering turbidite production at a centennial timescale (270-430 years)

Multiscale analysis of waves reflected by complex interfaces: Basic principles and experiments

International audience[1] This paper considers the reflection of waves by multiscale interfaces in the framework of the wavelet transform. First, we show how the wavelet transform is efficient to detect and characterize abrupt changes present in a signal. Locally homogeneous abrupt changes have conspicuous cone-like signatures in the wavelet transform from which their regularity may be obtained. Multiscale clusters of nearby singularities produce a hierarchical arrangement of conical patterns where the multiscale structure of the cluster may be identified. Second, the wavelet response is introduced as a natural extension of the wavelet transform when the signal to be analyzed (i.e., the velocity structure of the medium) can only be remotely probed by propagating wavelets into the medium instead of being directly convolved as in the wavelet transform. The reflected waves produced by the incident wavelets onto the reflectors present in the medium constitute the wavelet response. We show that both transforms are equivalent when multiple scattering is neglected and that cone-like features and ridge functions can be recognized in the wavelet response as well. Experimental applications of the acoustical wavelet response show how useful information can be obtained about remote multiscale reflectors. A first experiment implements the synthetic cases discussed before and concerns the characterization of planar reflectors with finite thicknesses. Another experiment concerns the multiscale characterization of a complex interface constituted by the surface of a layer of monodisperse glass beads immersed in water. Citation: Le Gonidec, Y., D. Gibert, and J.-N. Proust , Multiscale analysis of waves reflected by complex interfaces: Basic principles and experiments

Expression sédimentologique et modélisation des fluctuations glaciaires. Exemple des dépôts du Protérozoïque terminal au Mali occidental

The main purpose of this work is to illustrate the sedimentary record of glacially induced climatic fluctuations in terms of genetic stratigraphie units. The first chapter points out the general conditions which must have been brought together to give an answer to the main objectives of this work. These conditions mainly concern the studied area and the analytical method. The basin taken into account to trace out glacioclimatic relative sea-level changes is the late Proterozoic Bakoye Group in Wassangara basin in Western Mali (West Africa). The main reasons of this choice are : the stable epicratonic context, the glaciomarginal (" periglacial " s.\.) setting with respect to the paleocenter of the Late Proterozoic icesheet, and the exceptional quality of exposures to observe paleo-shorelines evolution in space and time. The method of study is an adaptation of sequence stratigraphy methodology to a very high resolution sedimentoïogic analysis in continental to marine transitional zones. Baselevel concept had been preferred to sea-level paradigm in order to describe more accurately the accommodation space variations (space available for the sediment to accumulate). This already ancient , but renewed, tool makes easier the comprehension of space and time evolution of the dynamic link between contemporaneous erosionnal and depositional areas. On the contrary of sealevel, baselevel concept can be used either in marine or in non marine paleo-environments. The second chapter defines the different orders of sequences encountered in Wassangara basin from a detailled analysis of a typical exposure of marine and non marine sediments. The elementary stratigraphie event or motif is made up of three différents fades assemblages or systems tracts bounded by three différents kinds of surfaces : maximum ßooding hiatal surfaces at the base of progradational assemblages, emersive erosional surfaces at the base of continental assemblages, transgressive erosional surfaces at the base of aggra-dational assemblages. These three différents kinds of surfaces, in each elementary event, merge out together towards non marine realm to form an intraeolian superbounding surface. The proeminent physical surface of erosion made up of the local and partial intersection in space of an intraeolian superbounding surface, an emersive surface and a transgressive surface corresponds to the general concept of unconconformity. The second order of sequence defined in Wassangara basin corresponds to a vertical and lateral stacking of the elementary events. Three sets of motifs had been distinguished : seaward stepping (SS), landward stepping (LS) and vertically stacked events shifted either seaward or landward (VS). The third chapter is a detailed and systematic description of fades and fades assemblages of the eleven motifs distinguished. A large and continuous span of depositional environments is illustrated from eolian dunes deposits to outershelf sandridges. The end of the chapter exhibits general and specific characteris¬ tics of the different kinds of surfaces and depositional assemblages. Allocyclic and a utocyclic controls on sedimentary bodies geometries and compositions are discussed. The fourth chapter illustrates two different interpretation procedures in sequence stratigraphy analysis, at marine to non marine rocks contact : unimodal considering a vertical surimposition of shallowing up sequences, and bimodal dealing with a succession of shallowing/deepening up sequences. Only the later leads to accurate three dimensional reconstructions of depositional sequences. Into each motif, the unconformity (i.e. intraeolian supersurface, emersive surface and transgressive surface pro parte ) is the diachronous physical break which separates sediments deposited during base-level fall time (progradational assemblage) and sediments deposited during baselevel rise time (continental and aggradational assemblages). Each motif into one set (LS, VS, SS) is characterised by a specific geometry, lithology and volumetric partitionning of sediments between baselevel fall and baselevel rise time. Landward stepping or seaward stepping events are strictly associated respectively with baselevel rise and baselevel fall periods. Vertically stacked motifs, shifted landward, sign the beginning of baselevel fall time. Vertically stacked motifs, shifted seaward, characterise the end of baselevel rise time. Wassangara basin stratigraphie record corresponds to the surimposition of baselevel fall/rise cycles at different scales. From the smaller to the larger one we have distinguished : (1) elementary event, (2) groups of elementary events, (3) the whole sediment pile in Wassangara area. The fifth chapter is a discussion about the origin of the observed superimposed baselevel cycles in the basin. The duration and the proposed origin for each of them are the followings : -elementary event : 100,000 years of duration, Milankovitch eccentricity cycles time span, glacial advance and retreat cycles ; -groups of motifs cycle : 1 Ma or less, glacial/interglacial stages ; -whole stacking sequence in Wassangara basin : a few Ma, glacial epochs time span, probably modified by intraplates stresses ; -whole Bakoye Group ; 10 Ma, the entire glacial period, tectonic activity in the Mauritanides fold belt. Most of the sequences are controlled either by tectonic and climatic processes but the study of sediment transfert at the elementary events scale shows how external factors which contrain the deposition of high resolution sequences, predominantly of climatic origin , control the geometry of mixed climatic and tectonic origin higher order sequences.Cet ouvrage propose d'illustrer le mode d'enregistrement dans les dépôts sédimentaires des fluctuations climatiques d'origine glaciaire, par l'intermédiaire d'une analyse stratigraphique en termes d'éléments significatifs du point de vue de la géodynamique globale. Le premier chapitre précise les conditions qui ont dû être réunies pour répondre aux objectifs fixés par l'étude. Ces conditions ont affecté notamment le choix de l'objet d'étude et la méthode d'analyse utilisés. L'objet pris en considération est le bassin protérozoïque terminal de Wassangara au Mali occidental (Groupe du Bakoye). Ce bassin présente les caractéristiques optimales requises pour tracer les fluctuations glaciocli-matiques du niveau relatif de la mer : une situation épicratonique stable, marginale par rapport au centre de la glaciation contemporaine du dépôt des sédiments, et des conditions exceptionnelles d'affleurement permettant d'observer l'évolution dans l'espace et dans le temps des paléolignes de rivages. La méthode d'analyse utilisée répond aux idées générales de la stratigraphie séquentielle, adaptées pour obtenir une meilleure adéquation à l'étude des zones littorales, et une analyse stratigraphique de très haute résolution. Le concept de niveau de base a été préféré à celui de niveau de la mer pour décrire les variations de l'accommodation (espace disponible pour que le sédiment s'y accumule). Cet outil présente deux avantages : il rend "intellectuellement manipulable" l'évolution, dans l'espace et dans le temps, des relations dynamiques entre les zones en érosion et les zones en accumulation et, au contraire du niveau de la mer, il est utilisable tant en domaine intracontinental qu'en domaine marin. Le second chapitre définit, à partir d'un exemple choisi spécifiquement dans des dépôts littoraux, deux ordres de séquences de dépôts emboîtées qui permettent de décrire toute l'architecture du bassin de Wassangara. Le motif stratigraphique élémentaire est composé de trois types d'assemblages de faciès, limités par trois types de surfaces : des surfaces d'inondation maximale de non-dépôt situées à la base des assemblages de progradation, des surfaces érosives d'émersion à la base des assemblages continentaux, des surfaces éro-sives de transgression à la base des assemblages d'agradation. Ces trois types de surfaces s'amalgament en domaine intracontinental pour former une supersurface de discontinuité intra-éolienne. Le passage latéral, du domaine continental au domaine marin, d'une supersurface intra-éolienne à une surface érosive d'émersion puis à une surface de transgression pro parte forme une seule et même surface physique d'érosion appelée "unconformity". Le second ordre de séquence correspond à une succession verticalement et latéralement ordonnée de onze motifs élémentaires. Parmi ceux-ci, trois groupes sont distingués : des motifs en déplace¬ ment vers le bassin (SS, "Seaward Stepping"), des motifs en déplacement vers le continent (LS, "Landward Stepping") et des motifs en empilement vertical (VS, "Vertical Stacking"), en position déplacée soit vers le bassin soit vers le continent. Le troisième chapitre est une description systématique des assemblages de faciès pour chacun des mo¬ tifs rencontrés. Un très large spectre d'environnements de dépôts est illustré de manière continue entre un domaine éolien dunaire et un domaine de plate-forme ouverte à " sandridges " . Leurs évolutions latérales et verticales sont à chaque fois prises en compte. La fin du chapitre met en exergue les caractères discrimi¬ nants fondamentaux pour chaque type de surface et chaque assemblage de faciès, et montre l'altération du signal autocyclique (dynamique de dépôt) au sein d'un corps sédimentaire par les phénomènes allocycliques (facteurs de contrôle externes). Le quatrième chapitre illustre les deux types d'analyses séquentielles verticalistes possibles à la transition entre le domaine continental et le domaine marin : unimodale à successions simples de séquences négatives, ou bimodale à alternances de séquences positives et négatives. Seule l'analyse bimodale permet de rendre compte de la géométrie tridimensionnelle observée à l'affleurement. Dans chaque motif, 1' "unconformity" marque l'inversion entre une phase de chute du niveau de base, contemporaine du dépôt de l'assemblage de progradation, et une phase de remontée avec mise en place des assemblages degradation et continentaux. En fonction de leur position dans le bassin (LS, VS, SS) les motifs élémentaires présentent des caractéristiques spécifiques : géométrie, composition, partitionnement volumétrique des sédiments entre les phases de chute et de relèvement du niveau de base. Les motifs en translation vers le continent (LS) ou vers le bassin (SS) caractérisent respectivement la remontée et la chute du niveau de base. Les motifs en empilement vertical (VS) sont situés soit en début de chute lorsqu'ils sont en position déplacée vers le continent, soit en début de remontée lorsqu'ils sont en position déplacée vers le bassin. Trois ensembles, dont le dernier est incomplet, ont été distingués à l'intérieur du cycle continu de variation du niveau de base que représente la séquence d'empilement. Chacun de ces ensembles correspond à une période de remontée puis de chute du niveau de base. Le cinquième chapitre propose une interprétation concernant l'origine des quatre cycles emboîtés de variations du niveau de base mis en évidence dans le bassin de Wassangara. Il s'agit : -d'un cycle à l'échelle du motif élémentaire, d'une durée de l'ordre de 100000 ans, situé dans la bande de fréquence des cycles de Milankovitch, et associé à des cycles d'avancée et de retrait glaciaire ; -d'un cycle à l'échelle des ensembles de motifs, d'une durée inférieure à 1 Ma, correspondant à une alternance de stades glaciaire/interglaciaire ; -d'un cycle à l'échelle de la séquence d'empilement, de quelques millions d'années, d'une durée équivalente à celles des époques glaciaires, mais aussi des déformations intrap laques ; -d'un cycle pour le Groupe du Bakoye qui forme l'essentiel des dépôts liés à la période glaciaire du Protérozoïque terminal sur le craton, d'une durée de l'ordre d'une dizaine de millions d'années, mais aussi contemporain d'événements tectoniques dans la chaîne bordière des Mauritanides. Toutes ces séquences sont sous le double contrôle du climat et de la tectonique. Cependant, l'étude des bilans de transferts de matières à l'échelle des unités génétiques de dépôts permet de montrer comment les contraintes imposées par les facteurs externes, à l'échelle de la séquence haute résolution (climatiques), contrôlent la géométrie des séquences d'ordre supérieur (climatiques et tectoniques).Proust Jean-Noël. Expression sédimentologique et modélisation des fluctuations glaciaires. Exemple des dépôts du Protérozoïque terminal au Mali occidental. Strasbourg : Institut de Géologie – Université Louis-Pasteur, 1992. 176 p. (Sciences Géologiques. Mémoire, 92