18 results on '"Shallow Marine"'
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2. Eocene foraminiferal biofacies in Kutch Basin (India) in context of palaeoclimate and palaeoecology
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Sonal Khanolkar and Pratul Kumar Saraswati
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Hyperthermal events ,Shallow marine ,Morphogroups ,Carbonate platform ,Stable isotopes ,Eocene ,Paleontology ,QE701-760 - Abstract
Abstract The Eocene Epoch passed through multiple hyperthermal events and recorded highest temperatures in the Cenozoic. Very few studies from Eocene palaeotropical sites have recorded changes in shallow marine foraminiferal assemblages. The present study investigates the foraminiferal biofacies of shallow marine successions from a palaeotropical site in western India (Kutch Basin) to understand the palaeoclimate and its impact on the ecology of foraminifera. The sections were biostratigraphically constrained using planktic and larger benthic foraminifera. Four biofacies are recognized by detrended correspondence analysis of the sample-wise distribution of foraminifera. Low diversity and dwarfed foraminifera characterize Bulimina–Chiloguembelina biofacies (SBZ5/6–SBZ10), corresponding to the interval of Paleocene–Eocene Thermal Maxima (PETM) and Eocene Thermal Maxima 2 (ETM 2). Rectilinear benthic foraminifera and biserial and triserial planktic foraminifera, typical of high runoff, upwelling or eutrophic conditions, are dominant taxa in this biofacies. The specialist taxa increased significantly in Asterigerina–Cibicides biofacies, corresponding to SBZ11 (Early Eocene Climatic Optimum, EECO), and the environment became oligotrophic. The Jenkinsina–Brizalina biofacies (E12) is distinguished by foraminiferal assemblage ecologically like that of Bulimina–Chiloguembelina biofacies. It is characterized by high abundance of rectilinear benthic foraminifera and bloom of triserial planktic foraminifera, suggesting eutrophy and high runoff at the initiation of Middle Eocene Climatic Optimum (MECO). The foraminifera were more diverse and abundant in Cibicides–Nonion biofacies. The highly diverse larger benthic foraminiferal assemblage in this biofacies, signify warm and clear-water oligotrophic sea that promoted the development of platform carbonate in Kutch Basin and other basins in western India. The EECO and MECO did not have an adverse impact on shallow marine foraminifera, and particularly the larger benthic foraminifera attained high diversity, high abundance, larger size and wider latitudinal distribution in the middle Eocene.
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- 2019
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3. BIOEROSION OF THE PLIO-PLEISTOCENE TRANSGRESSION OF SOUTHERN ITALY
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RICHARD G. BROMLEY and ASSUNTA D'ALESSANDRO
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Bioerosion ,Trace fossil ,Shallow marine ,Palaeoenvironmental indicators ,Taxonomy. ,Geology ,QE1-996.5 ,Paleontology ,QE701-760 - Abstract
During the Pliocene and Lower Pleistocene, the structural unit of the Murge was largely submerged by a marine transgression. As the sea advanced, the limestone basement surface was invaded by bioeroding organisms whose borings are well preserved through burial by the calcareous sediments of the Calcarenite di Gravina formation. The tilted—block topography of the submerging Murge unit produced different coastal environments ranging from protected gentle slopes to exposed vertical clifflines. Details of the bioerosion were examined at four localities that cover a range of those environments. The 35 ichnotaxa recognized (excluding microborings) are treated taxonomically where necessary, and their relative distributions and occurrences are studied. Three new ichnospecies are erected: Gastrochaenolites cor, Maeandropolydora barocca and M. crassa. Four recurring assemblages are recognized: Caulostrepsis/ Maeandropolydora assemblage, G. cor assemblage, G. torpedo/ Entobian assemblage and a High Diversity Entobian—Dominated assemblage. All four indicate shallow marine environments, their relative distributions being influenced by environmental factors such as the attitude of the substrate surface and the hydrodynamic energy level.
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- 2020
4. Hutchison Medallist 1. Wave-Dominated to Tide-Dominated Coastal Systems: A Unifying Model for Tidal Shorefaces and Refinement of the Coastal- Environments Classification Scheme
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Byongcheon Yang, Romain Vaucher, Shahin E. Dashtgard, and Robert W. Dalrymple
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Ripple marks ,mixed process ,Social Sciences and Humanities ,clastic sedimentology ,010504 meteorology & atmospheric sciences ,Lower shoreface ,Intertidal zone ,Storm ,010502 geochemistry & geophysics ,tidal shorefaces ,01 natural sciences ,Sedimentary depositional environment ,Paleontology ,Aggradation ,shallow marine ,mixed wave-tide ,General Earth and Planetary Sciences ,Sciences Humaines et Sociales ,Submarine pipeline ,coastal classification ,Geology ,Seabed ,0105 earth and related environmental sciences - Abstract
Coastal depositional systems are normally classified based on the relative input of wave, tide, and river processes. While wave- through to river-dominated environments are well characterized, environments along the wave-to-tide continuum are relatively poorly understood and this limits the reliability and utility of coastal classification schemes. Two tidal shoreface models, open-coast tidal flats (OCTF) and tidally modulated shorefaces (TMS), have been introduced for mixed wave-tide coastal settings. Following nearly two decades of research on tidal shorefaces, a number of significant insights have been derived, and these data are used here to develop a unified model for such systems. First, OCTFs are components of larger depositional environments, and in multiple published examples, OCTFs overlie offshore to lower shoreface successions that are similar to TMS. Consequently, we combine OCTFs and TMSs into a single tidal shoreface model where TMS (as originally described) and TMS-OCTF successions are considered as variants along the wave-tide continuum. Second, tidal shoreface successions are preferentially preserved in low- to moderate-wave energy environments and in progradational to aggradational systems. It is probably difficult to distinguish tidal shorefaces from their storm-dominated counterparts. Third, tidal shorefaces, including both TMSs and OCTFs, should exhibit tidally modulated storm deposits, reflecting variation in storm-wave energy at the sea floor resulting from the rising and falling tide. They may also exhibit interbedding of tidally generated structures (e.g. double mud drapes or bidirectional current ripples), deposited under fairweather conditions, and storm deposits (e.g. hummocky cross-stratification) through the lower shoreface and possibly into the upper shoreface.The development of the tidal shoreface model sheds light on the limitations of the presently accepted wave-tide-river classification scheme of coastal environments and a revised scheme is presented. In particular, tidal flats are components of larger depositional systems and can be identified in the rock record only in settings where intertidal and supratidal deposits are preserved; consequently, they should not represent the tide-dominated end-member of coastal systems. Instead, we suggest that tide-dominated embayments should occupy this apex. Tide-dominated embayments exhibit limited wave and river influence and include a wide range of geomorphological features typically associated with tidal processes, including tidal channels, bars and flats., Les systèmes de dépôts côtiers sont normalement classés en fonction de l’apport relatif des processus liés à la houle, aux marées et aux rivières. Si les environnements dominés par la houle et les rivières sont bien caractérisés, les environnements le long du continuum houle-marée sont relativement mal compris, ce qui limite la fiabilité et l’utilité des systèmes de classification des côtes. Deux modèles d’avant-plages tidales, les estrans ouverts (open-coast tidal flats; OCTF) et les avant-plages modulées par la marée (tidally modulated shoreface; TMS), ont été introduits pour les milieux côtiers mixtes, houle-marée. Suite à près de deux décennies de recherche sur les avant-plages tidales, un certain nombre d’informations importantes ont été obtenues et ces données sont utilisées ici pour développer un modèle unifié pour ces systèmes. Tout d’abord, les OCTF sont les composants de systèmes de dépôt plus vastes et, dans de nombreux exemples publiés, les OCTF recouvrent des successions sédimentaires allant du large à l’avant-plage inférieure, similaires à celle des TMS. Par conséquent, nous combinons les OCTF et les TMS en un seul modèle d’avant-plage tidale où les TMS (tel que décrit à l’origine) et les successions TMS-OCTF sont considérés comme des variantes le long du continuum houle-marée. Deuxièmement, les successions d’avant-plages tidales sont préférentiellement préservées dans des environnements ayant une houle faible à modérée et dans des systèmes progradant et aggradant. Il est probablement difficile de distinguer les avant-plages tidales de leurs homologues dominés par les tempêtes. Troisièmement, les avant-plages tidales, incluant à la fois les TMS et les OCTF devraient présenter des dépôts de tempête modulés par la marée, reflétant ainsi la variation de l’énergie des vagues de tempête sur le fond marin liée à la marée montante et descendante. Les avant-plages tidales peuvent également présenter une interstratification de structures générées par la marée (par exemple, des doubles drapages argileux ou des rides de courants bidirectionnelles) déposées pendant des conditions de beau temps, et des dépôts de tempête (par exemple, des stratifications en mamelons) au niveau de l’avant-plage inférieure et éventuellement de l’avant-plage supérieure.Le développement du modèle d’avant-plage tidale met en lumière les limites de la classification tripartite (houle-marée-rivière) des environnements côtiers actuellement acceptée et une classification révisée est présentée. En particulier, les OCTF et les estrans sont des composantes de systèmes dedépôt plus importants et ne peuvent être identifiés que dans le registre sédimentaire dans les milieux où les dépôts intertidaux et supratidaux sont préservés; par conséquent, ils ne devraient pas représenter le membre extrême des systèmes côtiers dominé par la marée. Nous suggérons plutôt que les baies dominées par la marée occupent cette place. Les baies dominées par les marées présentent une influence limitée des vagues et des rivières et comprennent un large éventail de caractéristiques géomorphologiques généralement associées aux processus de marée, notamment des chenaux, des barres et des platiers tidaux.
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- 2021
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5. Evidence for a 'Little Ice Age' glacial advance within the Antarctic Peninsula – Examples from glacially-overrun raised beaches
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Julie Zurbuchen, Lauren M. Simkins, Elizabeth R. Thomas, Regina DeWitt, Alexander R. Simms, Michael J. Bentley, and L. Reynolds
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010506 paleontology ,Archeology ,010504 meteorology & atmospheric sciences ,Raised beach ,01 natural sciences ,Neoglacial ,Shallow marine ,Climate change ,Sea level ,14. Life underwater ,Glacial period ,Ecology, Evolution, Behavior and Systematics ,Holocene ,0105 earth and related environmental sciences ,Coast ,Global and Planetary Change ,geography ,Glacial advance ,geography.geographical_feature_category ,History and Archaeology ,Paleontology ,Geology ,Glacier ,Last Glacial Maximum ,Post-glacial rebound ,Climate Action ,13. Climate action ,Moraine ,Earth Sciences ,Antarctica ,Physical geography ,Ice sheet - Abstract
Recognition of how dynamic the Antarctic ice sheets and glaciers were during the late Holocene has grown in recent years. Proxy data suggests the presence of Neoglacial advances but few moraines or glacial features from this time have been dated compared to glaciated landscapes of the Northern Hemisphere. Debate continues on whether parts of Antarctica experienced glacial advance at the same time as the “Little Ice Age” (LIA), which is well-documented in the Northern Hemisphere. We provide new evidence for late Holocene glacial fluctuations at three locations along the Antarctic Peninsula. A moraine or till sheet from a tidewater glacier cross cuts a series of dated raised beaches at Tay Head, Joinville Island along the northwestern Weddell Sea. At Spark Point, on Greenwich Island, a glacier has overrun Holocene raised beaches and a shell-bearing marine deposit is reworked into a glacial diamicton. A third site in Calmette Bay within the larger Marguerite Bay also contains a recent moraine that cuts across a series of dated raised beach ridges. The new ages constraining these glacial advances are in broad agreement with the handful of other existing ages on moraines and proxy records suggestive of cooler conditions within the Antarctic Peninsula. Combining available timing constraints into a Bayesian model yields an age of 400 to 90 cal BP (1550–1860 CE; 95%) for the LIA across the Antarctica Peninsula. Consideration of a two-phase glacial advance within our Bayesian framework does fit more of the data from across the Antarctic Peninsula and suggests advances from 575 to 330 cal BP (1375–1620 CE) and 400 to 50 cal BP (1550–1900 CE). However, more work is needed to determine if such a two-phase advance occurred. Regardless, its similar timing within the Antarctic Peninsula to that of the Northern Hemisphere supports recent assertions of a volcanic or solar forcing for the LIA. These recent readvances also provide a possible mechanism for changes in the rates of Holocene relative sea-level change recorded across the Antarctic Peninsula suggesting that the Antarctic ice sheets may have been more responsive to past climate changes than previously thought and glacial isostatic adjustment from the LIA and possibly other Holocene glacial oscillations is superimposed upon the longer relaxation from the Last Glacial Maximum.
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- 2021
6. When Is a Barrier Island Not an Island? When It Is Preserved in the Rock Record
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Julia S. Mulhern, Cari L. Johnson, and Andrew N. Green
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geography ,geography.geographical_feature_category ,Upper shoreface ,010504 meteorology & atmospheric sciences ,Outcrop ,shoreface ,010502 geochemistry & geophysics ,Geologic record ,Inlet ,01 natural sciences ,facies model ,Paleontology ,Barrier island ,Aggradation ,barrier island ,Facies ,shallow marine ,General Earth and Planetary Sciences ,lcsh:Q ,transgressive deposits ,Progradation ,tidal inlet ,lcsh:Science ,Geology ,0105 earth and related environmental sciences - Abstract
Existing barrier island facies models are largely based on modern observations. This approach highlights the heterogeneous and dynamic nature of barrier island systems, but it overlooks processes tied to geologic time scales, such as multi-directional motion, erosion, and reworking, and their expressions as preserved strata. Accordingly, this study uses characteristic outcrop expressions from paralic strata of the Upper Cretaceous Straight Cliffs Formation in southern Utah to update models for barrier island motion and preservation to include geologic time-scale processes. Results indicate that the key distinguishing facies and architectural elements of preserved barrier island systems have very little to do with “island” morphology as observed in modern systems. Four facies associations are used to describe and characterize these barrier island architectural elements. Barrier islands occur in association with backbarrier fill (FA1) and internally contain lower and upper shoreface (FA2), proximal upper shoreface (FA3), and tidal channel facies (FA4). Three main architectural elements (barrier island shorefaces, shoreface-dominated inlet fill, and channel-dominated inlet fill) occur independently or in combination to create stacked barrier island deposits. Barrier island shorefaces record progradation, while shoreface-dominated inlet fill records lateral migration, and channel-dominated inlet fill records aggradation within the tidal inlet. Barrier islands are bound by lagoons or estuaries and are distinguished from other shoreface deposits by their internal facies and outcrop geometry, association with backbarrier facies, and position within transgressive successions. Tidal processes, in particular, tidal inlet migration and reworking of the upper shoreface, also distinguish barrier island successions. In sum, this study expands barrier island facies models and provides new recognition criteria to account for the complex geometries of time-transgressive, preserved barrier island deposits.
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- 2021
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7. Sedimentary Architecture of Storm-Influenced Tidal Flat Deposits of the Upper Mulichinco Formation, Neuquén Basin, Argentina
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Héctor A. Leanza, Olivier Galland, Ivar Midtkandal, and Arve Sleveland
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010504 meteorology & atmospheric sciences ,Outcrop ,preservation ,Fluvial ,Storm ,wave ,Structural basin ,010502 geochemistry & geophysics ,01 natural sciences ,Paleontology ,Mulichinco Formation ,tidal ,shallow marine ,Facies ,General Earth and Planetary Sciences ,lcsh:Q ,Sedimentary rock ,mixed-process ,Sedimentology ,lcsh:Science ,Paleocurrent ,Geology ,0105 earth and related environmental sciences - Abstract
This study reports on the Lower Cretaceous upper Mulichinco Formation in the Neuquén Basin, west-central Argentina. The studied succession comprises shallow marine strata, deposited in a mixed wave and tidal flat environment where ebb-tidal currents dominated. We describe mixed storm- and tide-influenced deposits within progradationally stacked high-frequency sequences and discuss process interaction, sediment dispersal, and preservation potential. These storm and tidal deposits mix spatially on bed, bedset, and sequence scales, suggesting multi-scale process interactions. The study investigates a 12-km-long continuous outcrop, oriented sub-parallel to the paleocoastline. The succession comprises subtidal flat and meandering tidal channel complexes, with interbedding and interfingering of storm and tidal deposits. The tidal deposits are widespread and comprise moderately sorted sandstones with bimodal paleocurrent directions, single and double mud drapes, reactivation surfaces, and inclined heterolithic stratification. Varying bimodal paleocurrent directions suggest that the paleocoastline was irregular, consisting of both protrusions and bays. Storm deposits are mainly found erosively interbedded with subtidal flat sandstones, and exhibit decimeter-thick, well-sorted hummocky and swaley cross-stratified sandstones. These storm deposits show systematic lateral variations in abundance, from dominant to absent, which are linked to subtle variations in water depth along the irregular paleocoastline. As the tidal deposits are widespread across the study area, and with no significant facies change, the varying dispersal of storm-influenced deposits is considered a product of wave refraction, with converging and diverging wave energy at interpreted positions of coastal protrusions and embayments, respectively. Consequently, the irregular paleocoastline morphology caused spatial variability in wave impact and controlled preservation of interbedded storm and tidal deposits at the coastal protrusions while facilitating complete tidal remobilization of sediments in the embayments. With no evidence for fluvial influence, ebb-tidal currents are considered as the main drivers for sediment dispersal onto the subtidal flat, through the meandering tidal channels.
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- 2020
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8. Late Pleistocene sea-level oscillations (MIS 10–2) recorded in shallow marine and coastal plain sediments of the southern Wanganui Basin, New Zealand
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Hughes, Glenn R. and Kennedy, David M.
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SEA level , *PLEISTOCENE paleoclimatology , *SEDIMENTS , *GEOLOGICAL basins , *SEDIMENTATION & deposition , *QUATERNARY stratigraphic geology , *PALYNOLOGY , *PALEONTOLOGY - Abstract
Abstract: The northern Wanganui Basin, New Zealand, is one of the key global sites for understanding marine cyclic sedimentation during the Quaternary. This paper presents the first evidence of marine cyclic sedimentation from its central-southern parts. Sedimentological, micropalaeontological and palynological analyses on a 280-m-deep borehole encountered units dating back to MIS 10. The sequence includes four marine cycles spanning MIS 9–5, which are overlain by terrestrial fluvial aggradation surfaces dating from MIS 4–2. Each marine unit represents a progressively shallowing depositional environment from the mid-shelf to coastal plain. This is overlain by a terrestrial sequence of lowstand fluvial terraces. Localized fault movements appear to have influenced the sedimentary character of the sequence during MIS 7a and 5e producing basement highs which provided protection to the shoreline. The cyclothems described in this paper now extend the already extensive, previously described record from MIS 17–10 to produce a combined eustatic record of Quaternary sea level change within the basin to MIS 5. They also provide an excellent example of the sedimentary response of a coastal basin to a progressive loss of sedimentation accommodation space. [Copyright &y& Elsevier]
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- 2009
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9. Tectonic, eustatic and climatic controls on marginal‐marine sedimentation across a flexural depocentre: Paddy Member of Peace River Formation (Late Albian), Western Canada Foreland Basin
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Jessica R. Krawetz, A. Guy Plint, Ireneusz Walaszczyk, Kathleen M. Vannelli, Robin A. Buckley, AAPG Grant-in-Aid program, NSERC, and NCN
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010504 meteorology & atmospheric sciences ,Stratigraphy ,Environmental Science (miscellaneous) ,alluvial ,010502 geochemistry & geophysics ,Oceanography ,01 natural sciences ,Unconformity ,lagoonal ,Conglomerate ,Paleontology ,Aggradation ,albian ,tectonics ,Geomorphology ,Foreland basin ,0105 earth and related environmental sciences ,western Canada foreland basin ,Geology ,15. Life on land ,Cretaceous ,sea-level change ,clastic sedimentation ,Clastic rock ,climate-change ,shallow marine ,Alluvium ,cretaceous ,Marine transgression - Abstract
In north-central Alberta and adjacent British Columbia, clastic strata of the middle to late Albian Peace River and Shaftesbury formations were deposited in alluvial to shallow marine environments across the foredeep of the Western Canada Foreland Basin. A high-resolution, log and core-based allostratigraphic framework for the Paddy Member of the Peace River Formation established nine allomembers, PA to PI, bounded by flooding surfaces and apparently equivalent non-marine surfaces. Within the estimated 2 Myr. duration of the Paddy, allomembers allow the evolving palaeogeography and changing relationship between accommodation and sedimentation rates to be analysed on time-steps on the order of 105 yrs. Paddy strata fill an arcuate depocentre ~ 300 km wide, across which the rocks thin eastward from 125 m to ~ 5-10 m. The northern part of the basin is occupied by muddy, offshore marine deposits that pass abruptly southward into a linear, WSW-ENE-trending body of sandstone deposited in a wave-dominated barrier-strandplain, at least 350 km long. Extending > 200 km to the south of the strandplain was a region of shallow brackish to freshwater lagoons and lakes that graded to the SW into alluvial facies. Within the lagoon region, few m thick, elongate and patchy sandstones represent river dominated deltas. In allomembers PA to PG, these sandstones are concentrated in the west and south, implying supply from the western Cordillera. In allomembers PH and PI, sandstones are mainly in the east and have a distinctive, quartz-rich composition. They can be correlated eastward into the coeval Pelican Formation, and were probably sourced from the Canadian Shield on the opposite side of the basin. In the western foredeep, alluvial rocks comprise aggradational, unconfined floodplain deposits with ribbon sandstones, dissected, on at least nine separate levels, by paleovalleys that are confined to the proximal foredeep. Valleys are 10-20 m deep, few km-wide, and filled with multi-storey channel-bars of pebbly coarse sandstone or conglomerate. Valleys cut down from well-developed interfluve palaeosols that record a falling and then rising water table. Alternating aggradation and degradation, and advance and retreat of the alluvial gravel front is attributed to cycles of varying rainfall intensity, rather than tectonism or eustasy. Apparently coeval transgressive-regressive successions in the lagoon and marine regions are attributed to few-m scale eustatic changes. On the NE margin of the basin, tidal sandstone fills a northward-opening estuary cut on the basal Paddy unconformity. This sandstone contains the first well-documented specimens of Gnesioceramus comancheanus (Cragin), proving contemporaneity with at least part of the marine Joli Fou Formation to the east. Paddy allomembers change shape upward from short blunt wedges, through more acutely tapered wedges, to sheets. This change reflects initially rapid flexural subsidence, attributed to active thickening of the adjacent orogenic wedge. A waning rate of deformation permitted wider dispersal of sediment across the basin, driving broad isostatic subsidence beneath increasingly sheet-like rock bodies. A major hiatal surface, VE3, records non-deposition or subtle erosion attributed to erosional unloading and uplift of the adjacent orogen. A subsequent marine transgression is attributed to renewed thickening of the tectonic wedge that triggered deposition of marine mudstone that thickens westward from 0 to > 110 m over 300 km. A postulated Milankovitch-band climatic control on both local gravel supply (via fluctuating rainfall), and shoreline movement (via ?Antarctic glacio-eustasy or groundwater storage), might account for cycles of alternating incision and aggradation in the alluvial realm. The same mechanism may also explain why shallow marine units such as the Cretaceous Viking and Cardium formations contain abundant conglomerate in lowstand shoreface deposits (higher river discharge), yet have highstand shorelines dominated by sandstone (lower river discharge). This article is protected by copyright. All rights reserved.
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- 2017
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10. A New Ichnospecies of Arthrophycus from the Upper Cambrian-Lower Tremadocian of Northwest Argentina: Implications for the Arthrophycid Lineage and Potential in Ichnostratigraphy.
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Mángano, M. Gabriela, Carmona, Noelia B., Buatois, Luis A., and Guinea, Fernando Muñiz
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PALEONTOLOGY , *FOSSILS , *PALEONTOLOGICAL excavations , *EDUCATION - Abstract
A new ichnospecies of Arthrophycus Hall 1852, A. minimus , is described from Upper Cambrian-Lower Tremadocian, shallow-marine strata of northwest Argentina. This new ichnospecies consists of small, long, regularly annulated hypichnial elements displaying subcircular to squarish cross-section and a ventral median groove. Side branches are occasionally present, but palmate, fan-like structures and scribbling patterns are absent. We adopt a relatively narrow diagnosis of Arthrophycus , suggesting that roughly annulated, cylindrical structures should not be included in this ichnogenus, unless other diagnostic features (i.e., squarish cross-section, median groove, zipper-like annulations) are also present. Arthrophycus is a common ichnotaxon in Ordovician-Silurian shallow-marine siliciclastic environments. Post-Paleozoic occurrences are removed from Arthrophycus . Arthrophycus has been proposed as a biostratigraphic index fossil in Ordovician-Silurian rocks. The presence of A. minimus in the Santa Rosita Formation of northwest Argentina indicates that Arthrophycus ranges at least from the Upper Cambrian-Lower Tremadocian with probable representatives in the Lower Cambrian and, therefore, its biostratigraphic utility is extended. Arthrophycus minimus represents the first Cambrian occurrence exhibiting not only fine, diagnostic morphologic features, but also the classical Arthrophycus behavioral pattern in dense monoichnospecific assemblages. The exploratory behavioral pattern displayed by A. minimus is simpler than that of the younger ichnospecies, particularly A. brogniartii, A. alleghaniensis, and A. lateralis . This is consistent with the basal position of A. minimus within the arthrophycid lineage. [ABSTRACT FROM AUTHOR]
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- 2005
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11. Ichnofabric analysis of the shallow marine Nukhul Formation (Miocene), Suez Rift, Egypt: implications for depositional processes and sequence stratigraphic evolution
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Malpas, J.A., Gawthorpe, R.L., Pollard, J.E., and Sharp, I.R.
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FOSSILS , *SEDIMENTARY rocks , *LAND settlement , *PALEONTOLOGY - Abstract
Abstract: The shallow marine, early, syn-rift, Miocene, Nukhul Formation, Suez Rift, Egypt, is highly bioturbated and allows relationships between changes in trace fossils and ichnofabrics within a shallow marine depositional system to be documented and placed in a high resolution sequence stratigraphic framework. Seven ichnofabrics are present in a succession of interfingering, calcareous mudstones and calcarenites forming coarsening-up units of up to 30 m thick, bounded by marine flooding surfaces. The units grade upwards from a basal mudstone package with bed parallel concretions and a Planolites–Chondrites ichnofabric (offshore), through a coarsening-up succession of alternating calcarenites and mudstones with Thalassinoides–mottled sediment (offshore transition), Ophiomorpha irregulaire (lower shoreface), Ophiomorpha nodosa–Thalassinoides (lower middle shoreface), Thalassinoides–Taenidium (middle shoreface) and O. nodosa (upper shoreface) ichnofabrics. Gastrochaenolites (hardground) ichnofabric is separate, as it is not genetically related to the other ichnofabrics. Ichnofabric development is primarily controlled by depositional environment, e.g. bottom water oxygenation, sediment type, food abundance and energy level, which control substrate colonisation, sedimentation rate. Marine flooding surfaces are generally well-cemented and marked by distinctive epifaunal and infaunal colonisation and can be traced out from proximal to distal settings over distances of >5 km. The epifaunal colonisation in proximal settings consists of abundant oysters and corals with the substrate below marine flooding surfaces containing abundant Thalassinoides and Ophiomorpha isp. Abundance and diversity of epifauna and trace fossils and burrow size decreases distally into the basin. In the most distal settings, epifaunal colonisation is absent and only Planolites and Chondrites colonise the basinal mudstone. Marine flooding surfaces in the most distal settings are poorly cemented, but are marked by carbonate concretions 10–15 cm below the surface. [Copyright &y& Elsevier]
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- 2005
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12. Modern to Ancient Barrier Island Dimensional Comparisons: Implications for Analog Selection and Paleomorphodynamics
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Cari L. Johnson, John Martin, and Julia S. Mulhern
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accommodation ,Shore ,geography ,geography.geographical_feature_category ,Upper shoreface ,010504 meteorology & atmospheric sciences ,scaling relationships ,paleomorphodynamics ,010502 geochemistry & geophysics ,dimension prediction ,01 natural sciences ,Sedimentary depositional environment ,Paleontology ,Barrier island ,barrier island ,shallow marine ,Facies ,General Earth and Planetary Sciences ,lcsh:Q ,Transgressive ,Progradation ,lcsh:Science ,Sea level ,Geology ,0105 earth and related environmental sciences - Abstract
Ancient barrier islands are poorly understood relative to other clastic depositional environments, despite being prominent features along modern coastlines and important for understanding transgressive shoreline deposits. A new dataset of ancient barrier island dimensions (n=83 examples) addresses this knowledge gap with a quantitative analysis of barrier island sand body dimensions including thickness (vertical), length (shore-parallel direction), and width (shore-perpendicular direction). This dataset of barrier island deposits was compared to planform measurements made for modern islands (n=274), to investigate possible scaling relationships and other aspects of modern to ancient linkages. These measurements are nuanced and challenging to perform, and first-pass comparisons show that modern barrier islands should not be used as direct analogs for ancient systems. Nevertheless, results emphasize key depositional and preservation processes, and the dimensional differences between deposits formed over geologic versus modern time scales. Using the methods outlined herein, barrier island deposits appear to be 2-5x longer (p50 modern = 10.7 km; p50 ancient = 20.0 km), and 6-15x wider (p50 modern = 1.2 km; p50 ancient = 7.3 km) than modern barrier islands. We interpret the results to indicate that ancient barrier islands are time-transgressive deposits recording vertical amalgamation, and barrier island growth by lateral accretion, and progradation. When comparing single barrier islands, thickness measurements do not vary systemically between modern and ancient examples, suggesting that local accommodation dictates barrier island thickness as a preservation control. Gross length, width, and thickness measurements are too coarse for robust paleomorphodynamic calculations, therefore more detailed sub-environment analysis (e.g., upper shoreface delineation), with improved facies models, is required before rigorous quantifications can be generated. However, these initial comparisons do show scaling trends between length and width which could be leveraged, with caution, in the interim. As sea levels continue to rise, understanding barrier island motion and preservation will be central to predicting coastal change. Keywords: paleomorphodynamics, barrier island, scaling relationships, accommodation, shallow marine, dimension prediction, modern analog, reservoir, transgressive
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- 2019
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13. Triumph and tribulation for shallow water fauna during the Paleocene-Eocene transition; insights from the United Arab Emirates
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Beasley, Charlotte, Cotton, Laura, Al-Suwaidi, Aisha, LeVay, Leah, Sluijs, Appy, Ullmann, Clemens V., Hesselbo, Stephen P., Littler, Kate, Marine palynology and palaeoceanography, Marine Palynology, Marine palynology and palaeoceanography, and Marine Palynology
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PETM ,larger benthic forminifera ,Fauna ,Stratigraphy ,NERC ,Biodiversity ,Carbonates ,Palaeoenvironment ,RCUK ,Geology ,Shallow marine ,Paleontology ,Waves and shallow water ,Larger benthic foraminifera ,NE/M00578X/1 ,Paleogene - Abstract
The Paleocene–Eocene transition was a time of short-term rapid climatic and biotic change, superimposed on a long-term warming trend. The response of shallow tropical carbonate systems to past rapid warming is important to understand in the context of ongoing and future anthropogenic global warming. Larger benthic foraminifera (LBF) were abundant and important components of shallow water ecosystems throughout the early Paleogene and are sensitive to environmental change, making them ideal organisms to track shallow marine biodiversity. Furthermore, through the use of integrated bio- and chemostratigraphy it is possible to correlate the shallow (
- Published
- 2021
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14. Revisiting the age and palaeoenvironments of the Upper Jurassic–Lower Cretaceous? dinosaur-bearing sedimentary record of eastern Spain: implications for Iberian palaeogeography
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Esmeralda Caus, Ramón Mas, Pablo Suarez-Gonzalez, I. Emma Quijada, Rafael Royo-Torres, Alberto Cobos, Sonia Campos-Soto, Luis Alcalá, M. Isabel Benito, Ministerio de Economía y Competitividad (España), Universidad Complutense de Madrid, Gobierno de Aragón, European Commission, Instituto Aragonés de Fomento, Ministerio de Educación, Cultura y Deporte (España), Campos-Soto, Sonia, and Campos-Soto, Sonia [0000-0001-5418-7032]
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010506 paleontology ,biology ,Carbonate platform ,Stratigraphy ,Verterbrates ,Geology ,Coastal wetland system ,Structural basin ,010502 geochemistry & geophysics ,biology.organism_classification ,01 natural sciences ,Cretaceous ,Foraminifera ,Shallow marine ,Paleontology ,Larger benthic foraminifera ,Sedimentary rock ,Alluvium ,Siliciclastic ,Kimmeridgian–Tithonian ,Palaeogeography ,0105 earth and related environmental sciences - Abstract
An integrated stratigraphic, palaeontological, palaeoenvironmental and palaeogeographical study of the traditionally considered Upper Jurassic–Lower Cretaceous dinosaur-bearing sedimentary record (DSR) of eastern Spain is accomplished for the first time. Several areas where dinosaur fossils are abundant (western Maestrazgo and South-Iberian basins) have been studied in detail. In all the areas, the DSR comprises a carbonate-dominated lower part (CLP), and an essentially siliciclastic upper part (SUP). Deposition occurred in a shallow-very shallow marine carbonate platform, laterally connected towards the N and W to coastal and alluvial environments. The overall upwards evolution is regressive with a transgresive episode at the uppermost part. The DSR includes deposits previously assigned, depending on the studied area, from the Kimmeridgian to the Barremian (locally even to the Aptian–Albian). However, ages obtained in this work from larger benthic foraminifera (LBF), demonstrate a Kimmeridgian–Tithonian age (locally Kimmeridgian-Early Berriasian?) for the DSR. These findings have important implications regarding the age of dinosaur fossils of these deposits, traditionally assigned to the Jurassic-Cretaceous transition, or even to the Early Cretaceous, erroneously, and have necessitated a deep litho- and chronostratigraphic revision of the units previously established in the studied areas: new data indicate that the DSR is correlatable with deposits of the Villar del Arzobispo Fm and that the usage of the Aldea de Cortés and El Collado Fms, traditionally assigned to the Early Cretaceous, should be avoided. New data also reveal that the DSR should be correlated with other Kimmeridgian–Tithonian dinosaur-bearing deposits of Iberia, such as those of the Cameros Basin, Asturias and Portugal, and have encouraged a revision of the Iberian palaeogeography at that time. In fact, ages obtained from LBF agree with data provided by the systematics of dinosaurs, since dinosaur faunas of eastern Spain are similar to those of the other Late Jurassic Iberian areas, especially to those of the Lusitanian Basin., This research was funded by the Spanish projects CGL2014-52670-P, CGL2013-41295-P DINOTUR and CGL2015-69805-P of the Ministry of Economy and Competitiveness, by the “Sedimentary Basin Analysis” UCM Research Group (Ref. 910429), by the Department of Education, Culture and Sport and the Department of Innovation, Research and University of the Government of Aragón, by the FEDER Aragón 2014–2020 “Construyendo Europa desde Aragón” (FOCONTUR Quality Research Group E04_17R) and by the Instituto Aragonés de Fomento. The authors also thank the UCM Reseach Group “Sedimentary Geology, Paleoclimate and Environmental Change (Ref. 910198). Sonia Campos-Soto is supported by a FPU predoctoral fellowship of the Spanish Ministry of Education (Ref. FPU13/02978).
- Published
- 2019
15. Integrated sedimentological and ichnological study of the Coniacian sedimentation in North Sudetic Basin, SW Poland
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Stanisław Leszczyński
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Upper shoreface ,010504 meteorology & atmospheric sciences ,biology ,North Sudetic Synclinorium ,Geology ,010502 geochemistry & geophysics ,biology.organism_classification ,01 natural sciences ,Cyclothems ,Skolithos ,lithofacies ,Paleontology ,Ophiomorpha ,ichnofacies ,Thalassinoides ,shallow marine ,Ichnofacies ,Sedimentary rock ,paralic ,Cruziana ,trace fossils ,0105 earth and related environmental sciences - Abstract
Lithofacies and ichnological features of the Coniacian deposits of the upper part of Żerkowice Member and lowest part of the overlying Czerna Formation in southeastern part of the North Sudetic Synclinorium are described and their sedimentary palaeoenvironment is interpreted. The study confirms a shallow-marine to paralic/paludine palaeoenvironment. Sedimentation of the Żerkowice Member occurred in an upper shoreface environment dominated by waves, tidal currents and wave-generated alongshore currents, with an episodic encroachment of foreshore zone and shoal-water deltas. The interpretation is supported by a high-diversity assemblage of trace fossils with 21 ichnogenera, representing a stressed expression of the Skolithos Ichnofacies dominated by Ophiomorpha nodosa and a proximal expression of the Cruziana Ichnofacies with Thalassinoides and rare specimens of diverse other ichnotaxa. Sedimentation of the Czerna Formation commenced after a stasis, with at least a local hiatus caused by emergence, and proceeded in a laterally and vertically more varied environment, with transgressive coastal lagoons evolving into freshwater lakes and marshes and with a repetitive regressive intrusion of shoreface and shoal-water deltas. The emergence of the area is recorded by coal-bearing deposits with plant-root traces. Local occurrence of the Teredolites Ichnofacies in coal (peat) deposits above the base of the Czerna Formation indicates renewed marine flooding. Continuation of the latter is locally evidenced by a trace-fossil assemblage with 17 ichnogenera, representing proximal expression of the Cruziana Ichnofacies followed by distal expression of the Skolithos Ichnofacies in the overlying transgressive–regressive cyclothems. The palaeoenvironmental changes recorded by the sedimentary succession indicate bathymetric fluctuations and imply considerable shoreline shifts and palaeogeographic changes in the basin. These changes are interpreted as a combined signal of 2nd- and 3rd-order eustatic cycles, modified and partly obliterated by the effects of intrabasinal tectonic forcing and by palaeogeographically controlled variation in sediment supply.
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- 2018
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16. Cambrian trace fossils of the Cruziana ichnofacies from the Bikaner-Nagaur Basin, north western Indian Craton
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Dhirenda Kumar Pandey, Vineet Kumar, Rajesh Singh Shekhawat, and Alfred Uchman
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“Treptichnus” pedum ,Planolites ,India ,Geology ,Trace fossil ,Shallow marine ,Fodinichnia ,Paleontology ,Diplichnites ,Rajasthan ,Ichnology ,Rusophycus ,Ichnofacies ,new Ichnotaxa ,Marwar Supergroup ,Cruziana ,ichnology ,Earth-Surface Processes - Abstract
The Marwar Supergroup of the Bikaner-Nagaur Basin is composed of sediments deposited from the late Neoproterozoic (Ediacaran) to Upper Cambrian. The Nagaur Sandstone Formation of the Nagaur Group (uppermost division of the Marwar Supergroup) preserves trace fossils significant for establishing Early Cambrian biostratigraphic zones and depositional facies. Fifteen ichnospecies (and eight ichnogenera) identified in the Nagaur Sandstone Formation include “ Treptichnus” pedum , Cruziana cf . tenella , Cruziana isp., Diplichnites ispp. A, B, and C, Gyrophyllites isp., Lockeia isp., Merostomichnites isp., Monomorphichnus gregarius isp. nov., Monomorphichnus isp., Planolites isp. , Psammichnites isp., Rusophycus bikanerus isp. nov., Rusophycus cf. carbonarius , Rusophycus isp. and radial trace fossils. These trace fossils belong to ethological categories pascichnia, repichnia, cubichnia, and fodinichnia and represent arthropod and worm-like burrowing biota. The assemblage and a regional comparison with contemporaneous trace fossils in the eastern Gondwanan realm suggest that the sequence in the study area belongs to the Cruziana tenella Ichnozone and to Stage 2 (upper part of Terreneuvian), however the Middle Cambrian is not excluded. The trace fossil assemblage belongs to the archetypal Cruziana ichnofacies. Cross bedded sandstone, mud cracks and rainprints in the ichniferous strata of the Nagaur Sandstone Formation indicate deposition in an intertidal sand flat with channels that was exposed episodically.
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- 2014
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17. Lower Silurian stromatolites in shallow-marine environments of the South China Block (Guizhou Province, China) and their palaeoenvironmental significance
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Yue (李越 Li, Chao Ni, Shenyang (于海洋) Yu, Guan Wang, and Stephen Kershaw
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Lower Silurian ,010506 paleontology ,South china ,biology ,Foundation (engineering) ,Paleontology ,010502 geochemistry & geophysics ,Oceanography ,biology.organism_classification ,01 natural sciences ,Stromatolite ,Shihniulan Formation ,North Guizhou ,South China Block ,Shallow marine ,Block (telecommunications) ,China ,Ecology, Evolution, Behavior and Systematics ,Geology ,0105 earth and related environmental sciences ,Earth-Surface Processes - Abstract
In northern Guizhou Province (Upper Yangtze Platform, South China Block) two types of reef communities developed in the Lower Silurian (upper Aeronian, Llandovery) Shihniulan Formation; they are calcimicrobial- and metazoan-dominated structures, and existed because of northward deepening of the shallow-marine ramp setting in which they grew. Stromatolitic communities are the focus of the present study and dominated the shallowest reef structures, while metazoan-dominated reefs, previously described in other papers, grew in the outer shelf portion of the ramp. Stromatolitic reefs occur in several sections 23 (Daijiagou, Baishanxi, Jianba and Lianghekou), palaeogeographically close to Qianzhong Land. Within the stromatolite units, laminar sheets of microbial mats and columns are pronounced, with individual stromatolite thicknesses generally less than one meter. Some very small stromatolites are only centimeters in diameter and thickness. Stromatolitic units are cyanobacterial bindstones mostly associated with shales, siltstones and thin-bedded bioclastic limestones. Their growth was frequently punctuated by siliciclastic sediments, and their shallow-water nature is demonstrated by association with birds-eye structures, cross-stratified sediments, and Lingulella-bearing silts in intertidal or/and lagoonal environments. The stromatolites formed during a regression and erosion surfaces are common at the top of the Shihniulan Formation. The Tongzi Uplift, a short-duration expansion of Qianzhong Land, ended the deposition of the late Aeronian limestones. This study was supported by National Natural Science Foundation of China (granted No. 41072002, 41372022, XDB10010503 and 41521061).
- Published
- 2016
18. Shallow Off-Shore Archaeological Prospection with 3-D Electrical Resistivity Tomography: The Case of Olous (Modern Elounda), Greece
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Nikos Papadopoulos, Gianluca Cantoro, and Kleanthis Simyrdanis
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Hydrology ,Shore ,geography ,geography.geographical_feature_category ,underwater geophysics ,010504 meteorology & atmospheric sciences ,Geophysical imaging ,Science ,3D electrical resistivity tomography (ERT) ,010502 geochemistry & geophysics ,01 natural sciences ,Current (stream) ,Paleontology ,Real Time Kinematic ,shallow marine ,archaeological prospection ,Littoral zone ,General Earth and Planetary Sciences ,Bathymetry ,Electrical resistivity tomography ,Stratigraphy (archaeology) ,Geology ,0105 earth and related environmental sciences - Abstract
It is well known that nowadays as well as in the past the vast majority of human habitation and activities are mainly concentrated in littoral areas. Thus the increased attention to coastal zone management contributed to the development and implementation of shallow-water mapping approaches for capturing current environmental conditions. During the last decade, geophysical imaging techniques like electrical resistivity tomography (ERT) have been used in mapping onshore buried antiquities in a non-destructive manner, contributing to cultural heritage management. Despite its increased implementation in mapping on-shore buried archaeological remains, ERT has minimal to non-existent employment for the understanding of the past dynamics in littoral and shallow off-shore marine environments. This work presents the results of an extensive ERT survey in investigating part of the Hellenistic to Byzantine submerged archaeological site of Olous, located on the north-eastern coast of Crete, Greece. A marine area of 7100 m2 was covered with 178 densely spaced ERT lines having a cumulative length of 8.3 km. A combination of submerged static and moving survey modes were used to document potential buried and submerged structures. The acquired data from the marine environment were processed with two-dimensional and three-dimensional inversion algorithms. A real time kinematic global navigation satellite system was used to map the visible submerged walls and compile the bathymetry model of the bay. The adaptation of ERT in reconstructing the underwater archaeological remains in a shallow marine environment presented specific methodological and processing challenges. The in situ experience from the archaeological site of Olous showed that ERT provided a robust method for mapping the submerged archaeological structures related to the ancient built environment (walls, buildings, roads), signifying at the same time the vertical stratigraphy of the submerged sediments. The inherent limitation of employing ERT in a conductive environment is counterbalanced by the incorporation of precise knowledge for the conductivity and bathymetry of the saline water in the modelling and inversion procedure. Although the methodology definitely needs further refinement, the overall outcomes of this work underline the potential of ERT imaging being integrated into wider shallow marine projects for the mapping of archaeological sites in similar environmental regimes.
- Published
- 2016
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