Introduction to Morphodynamics of Sedimentary Patterns

Morphodynamics is a new discipline that investigates the formation and development of sedimentary patterns, i.e. the shapes of the cohesionless or cohesive boundaries of water bodies, evolving in response to the action of flowing water. Sedimentary patterns occur in fluvial, transitional, coastal and submarine environments. Their fascinating forms (e.g. dunes, meanders, alluvial fans, deltas, lagoons, coastal bars, tidal ridges, submarine fans) have attracted the attention of scientists. They also play a major role in fluvial, coastal and offshore engineering. The present monograph is the first of a series planned by an Editorial Committee comprising the four Authors. It provides a phenomenological introduction to the variety of patterns that will be investigated in the future Monographs. It also introduces to the mathematical theory of Morphodynamics, clarifying its nature of free boundary problem for the interface between a flowing water-sediment mixture and an erodible boundary

Blending single beam RoxAnn and multi-beam swathe QTC hydro-acoustic discrimination techniques for the Stonehaven area, Scotland, UK

Surface properties of the seabed in a 180 km2 area of coastal waters (14-57 m depth) off northeast Scotland were mapped by hydro-acoustic discrimination using single and multi-beam echosounders linked to signal processing systems (RoxAnn for the single beam, and Questor Tangent Corporation (QTC) Multiview for the multibeam). Subsequently, two ground truthing surveys were carried out, using grab and TV sampling. The RoxAnn and QTC-Multiview outputs showed strong similarity in their classifications of seabed types. Classifications generated by QTC-Multiview were used to supervise those based on seabed roughness and hardness indices produced by the RoxAnn system and thereby develop a ‘blended’ map based on both systems. The resulting hydro-acoustic classes agreed well with a cluster analysis of data on sediment grain sizes from the grab sampling, and indicated that the area could be described by distinct regions of surface texture and surficial sediments ranging from muddy sand to boulders and rock

Complex inner shelf environments: Observations and modeling of morphodynamics and scour processes

The inner continental shelf is a complex environmental system marked by sharp variations in bed roughness. Such heterogeneous systems account for 80% of the non-rocky inner shelves worldwide. Interactions among forces (waves, tides, turbulence, and bioturbation) and roughness elements (bed forms, rocks, and anthropogenic objects) exert major controls on sedimentary processes. This study attempts to advance the knowledge and understanding of the morphodynamics of the inner shelf. This study investigates scour and morphodynamic processes at Tairua, New Zealand; Cedar Island, Virginia; Indian Rocks Beach, Florida; and Beaufort Inlet, North Carolina. Using data from the field, the study develops new conceptual models to characterize and quantify the hydrodynamics and morphology of the seabed. The overall dataset includes side-scan sonograms, sub-bottom profiles, grain-size analyses, suspended sediment concentrations and hydrodynamic measurements. Analysis of the morphological data yielded a six-type classification of bottom features previously termed Rippled Scour Depressions (RSDs). The observed stratigraphic signature of RSDs does not agree with the previous interpretation of their formation. Striking spatial and temporal variations in seabed roughness produce significant enhancements of hydraulic roughness and turbulence over different substrates resulting in a self-organized, feed-back system of erosion (scour), deposition, and modified bed forms. The study demonstrates that widely used ripple models inadequately predict bed form geometry and behavior, especially during storms. Improved understanding of scour processes developed in this study leads to a new model of scour and burial of sea-bed objects such as naval mines and archaeological artifacts. When using the model to predict scour and burial, the greatest errors result from the uncertainties in the available forecasts of wave conditions. The model includes vertical variations in sediment characteristics as field observations indicate abrupt changes in substrate substantially alter the scour process. The overall study makes substantial contributions to the general understanding of RSD behavior by tying together detailed field studies with applicable insights from the area of complexity research. A new conceptual model of complex phase-transition is developed, involving critical process factors (hydrodynamics, underlying geology, and depth), which contribute to the observed spatial complexity and temporal variability of different RSD types

Sedimentology of the Glaciofluvial Deposits of Woolwich and Pilkington Townships

The Lake Wisconsin glaciofluvial deposits in Woolwich and Pilkington townships are examined for the purpose of environmental reconstruction and the establishment of the paleocurrent patterns. Sediment grain size and primary sedimentary structure are used to define sedimentary facies of environmental studies while the distribution of indicator pebbles, trends in clast size reduction and primary sedimentary structures and employed for paleocurrent analysis. The exposures most representative of the depositional sequences encountered are examined and provide an impression of the sedimentological characteristics of the various glaciofluvial deposits. Three distinctive types of glaciofluvial deposits can be identified on the basis of surface morphology and sedimentological characteristics. The ice-contact esker deposits form sharp-crested sinuous ridges and exhibit a central core of coarse massive gravel flanked occasionally by finer facies types. The proglacial outwash deposits are topographically flat to gently rolling and although crude horizontally stratified drift is disntiguishable from esker deposits by the irregular hummocky terrain and the frequency with which coarse gravels occur in a tabular cross-bedded form. Paleocurrent analysis reveals two ancient paleoflow systems. One system, associated with the esker and outwash deposits in the east, exhibits an east-west flow trend while the other system reveals a north-south component of flow coincident with the Elmira moraine and the adjacent outwash deposits. The two systems converge centrally and adopt a southwesterly flow direction. This information corresponds with independent evidence for a Lake Huron-Georgian Bay ice lobe and a Lake Ontario ice lobe and their subsequent withdrawal from the interlobate area toward their respective sources north and east

Sedimentary heterogeneity and petrophysical characterization of Barremian tsunami and barrier island/inlet deposits: The Aliaga outcrop as a reservoir analogue (Galve sub-basin, eastern Spain)

The present study examined two sandstone deposits in the Aliaga outcrop as a reservoir analogue over a distance of 200-m-long and attempted to establish a correlation between sand facies and the petrophysical properties of the sandstones in order to investigate the reservoir heterogeneity. The Aliaga reservoir analogue represents the upper part of Camarillas Fm., deposited during the Barremian synrift phase of the Galve sub-basin (Iberian Basin, Spain). It is characterized by a transitional sedimentary interval from sandy-dominant deposits to carbonate-dominant deposits, which were deposited under the same palaeoenvironmental conditions (in relation to systems of back-barrier sedimentation). The description of the Aliaga outcrop provided here consists of lithological descriptions of two sandstone deposits: a tsunami and a barrier island/inlet, at both mesoscopic (decimetres to tens of metres) and microscopic scales (millimetres to centimetres). Both deposits recognized at the basin scale were described in terms of sand grain size, sand sorting and cementation; further cores were drilled along outcrop to collect samples for porosity and permeability measurements. Both sandstone reservoirs are the result of different sedimentary processes that determined facies characteristics, as the different petrophysical properties observed in these deposits. Consequently, the sedimentary process controls the heterogeneity of the sandstones facies and thus, the sand heterogeneity controls the distribution of the petrophysical properties. The classification of sand facies in terms of sand sorting seems to be more appropriate for describing sand heterogeneity; accordingly, petrophysical parameters in both deposits were also influenced by sand sorting. The sand facies and petrophysics heterogeneity of the described deposits can be hierarchically ordered. First-order heterogeneity is related to the basin scale, second-order heterogeneity is related to genesis and the conditions of sediment deposition, and third-order heterogeneity is related to synsedimentary faults and/or post-sedimentation events.This research is a contribution to the project: Análisis de Cuencas Sedimentarias Continentales, of the Gobierno de Aragón, the Análisis de Cuencas Sedimentarias Group of the UCM-CAM, and the projects CGL2011-23717 (Ministerio de Ciencia e Innovación of the Spanish Government and FEDER) and UZ2015-CIE-10 (University of Zaragoza). Additional financial support was provided by a Cnpq (Conselho Nacional de Pesquisa e Desenvolvimento Tecnologico, Brasil) Research Grant (200147/2011-0) and an IAS Schema 1st session 2014 Postgraduate Grant to F. Veloso.Peer reviewe

Actuopaleoichnology of a modern Bay of Fundy macro-tidal flat: Analogy with a Mississippian tidal flat deposit (Hartselle Sandstone) from Alabama

Copyright 2019 Zachos and Platt Trace fossil zonation in the Hartselle Sandstone of Mississippian age (Chesterian: Visean-Serpukhovian) exposed on Fielder Ridge, Alabama is compared with modern macro-tidal flat ichnocoenoses on the Bay of Fundy at Lubec, Maine, and demonstrated to be analogous by sedimentologic and ichnotaxonomic criteria. The modern flat has minimal influence from either waves or freshwater influx, and can be divided into five distinct ichnocoenoses, characterized by surface traces (epichnia) and four sedimentologic facies defined by gross grain texture or hydrodynamic characteristics, but lacking significant surface traces. Several characteristics of tidal flat deposits in a fetch-limited, marine (i.e., non-estuarine), meso- to macro-tidal regime can be used to recognize similar environments as old as the late Paleozoic. These criteria include (1) limited influence of wind and waves on the depositional environment, (2) lack of significant freshwater influence and therefore any persistent brackish environments, (3) a distinct spatial distribution of microenvironments defined by substrate and exposure period, (4) high diversity of epichnial traces directly associated with microenvironments across the tidal flat, (5) generally low degree of reworking of traces by bioturbation but high degree of reworking by tidal currents, and (6) preservation of traces of predation and scavenging behavior on an exposed surface. These features, together with the regional depositional pattern of the Hartselle Sandstone interpreted as tide-influenced bars and shoals, support a meso- to macro-tidal interpretation of the depositional environment

Review of the geomorphological, benthic ecological and biogeomorphological effects of nourishments on the shoreface and surf zone of the Dutch coast

Most knowledge on the morphodynamic behaviour of shoreface and beach nourishments originates from data analysis studies. Numerical modeling tools have been used successfully in hindcasting behaviour of nourishments, but do not yet have the predictive power for reliably forecasting

Facies characteristics and diversity in carbonate eolianites

Carbonate eolian dunes can form huge sand bodies along the coasts but are seldom described in the pre-Quaternary record. The study of more than 600 thin-sections collected in present-day, Holocene and Pleistocene dunes from Sardinia, Crete, Cyprus, Tunisia, Morocco, Australia and Baja California confirms that these deposits can be easily misinterpreted as shallow marine at core or thin-section scale. The classical eolian criteria (fine-grained and well-sorted sands) are exceptional in carbonate dunes because the diversity of shapes and densities of carbonate particles lowers the critical shear velocity of the sediment thus blurring the sedimentary structures. Wind carbonate deposits are mainly heterogeneous in size and often coarse-grained. The paucity of eolianites in the pre-Quaternary record could be due to misinterpretation of these deposits. The recognition should be based on converging sedimentological and stratigraphic elements at core scale, and diagenetic (vadose diagenesis, pedogenetic imprints) and petrographical (grain verticalization, scarcity of micritic envelopes, broken and/or reworked foraminifera) clues in thin-section. Bioclastic or oolitic grainstones showing evidence of vadose diagenesis or pedogenetic imprints, should always be suspected of having an eolian origi