The Experts below are selected from a list of 1254 Experts worldwide ranked by ideXlab platform
Gabriela M Mangano - One of the best experts on this subject based on the ideXlab platform.
-
trace fossils sedimentary facies and parasequence architecture from the lower cretaceous mulichinco formation of argentina the role of fair weather waves in shoreface deposits
Sedimentary Geology, 2018Co-Authors: Lindsey J N Wesolowski, Gabriela M Mangano, Luis A Buatois, Juan Jose Ponce, Noelia B CarmonaAbstract:Abstract Shorefaces can display strong facies variability and integration of sedimentology and ichnology provides a high-resolution model to identify variations among strongly storm-dominated (high energy), moderately storm-affected (intermediate energy), and weakly storm-affected (low energy) shoreface deposits. In addition, ichnology has proved to be of help to delineate parasequences as trace-fossil associations are excellent indicators of environmental conditions which typically change along the depositional profile. Shallow-marine deposits and associated ichnofaunas from the Mulichinco Formation (Valanginian, Lower Cretaceous) in Puerta Curaco, Neuquen Basin, western Argentina, were analyzed to evaluate stress factors on shoreface benthos and parasequence architecture. During storm-dominated conditions, the Skolithos Ichnofacies prevails within the offshore transition and lower shoreface represented by assemblages dominated by Thalassinoides isp. and Ophiomorpha irregulaire. Under weakly storm-affected conditions, the Cruziana Ichnofacies is recognized, characterized by assemblages dominated by Thalassinoides isp. and Gyrochorte comosa in the offshore transition, and by Gyrochorte comosa within the lower shoreface. Storm-influenced conditions yield wider ichnologic variability, showing elements of both Ichnofacies. Storm influence on sedimentation is affected by both allogenic (e.g. tectonic subsidence, sea-level, and sediment influx) and autogenic (e.g. hydrodynamic) controls at both parasequence and intra-parasequence scales. Four distinct types of parasequences were recognized, strongly storm-dominated, moderately storm-affected, moderately storm-affected – strongly fair-weather reworked, and weakly storm-affected, categorized based on parasequence architectural variability derived from varying degrees of storm and fair-weather wave influence. The new type of shoreface described here, the moderately storm-affected – strongly fair-weather reworked shoreface, features storm deposits reworked thoroughly by fair-weather waves. During fair-weather wave reworking, elements of the Cruziana Ichnofacies are overprinted upon relict elements of the Skolithos Ichnofacies from previous storm induced deposition. This type of shoreface, commonly overlooked in past literature, expands our understanding of the sedimentary dynamics and stratigraphic architecture in a shoreface susceptible to various parasequence and intra-parasequence scale degrees of storm and fair-weather wave influence.
-
early triassic estuarine depauperate cruziana Ichnofacies from the sichuan area of south china and its implications for the biotic recovery in brackish water settings after the end permian mass extinction
Palaeogeography Palaeoclimatology Palaeoecology, 2017Co-Authors: Lijun Zhang, Gabriela M Mangano, Luis A Buatois, Xin Zhang, Shangqian Sun, Chao TaiAbstract:Abstract New ichnological data from the Lower Triassic (Induan) Dongchuan Formation (Longmendong, South China) record the recovery interval of marginal-marine communities following the end-Permian mass extinction. Here, we document six ichnogenera from the upper part of the Dongchuan Formation of Dienerian (Early Triassic) age in the Longmendong area, Sichuan Province, South China. These are Cylindrichnus , Diplocraterion , Palaeophycus , Planolites , Siphonichnus , and Teichichnus , illustrating a depauperate Cruziana Ichnofacies. Facies analysis suggests that the depauperate Cruziana Ichnofacies is present in deposits recording the transition from fluvial to tide-dominated estuarine settings. Compilation of worldwide brackish-water ichnofaunas from Permian (average alpha ichnodiversity = 6.2) to Triassic (average alpha ichnodiversity = 5.5) suggests that no significant ichnodiversity decrease took place in these settings as a result of the mass extinction and further implies that the impact of the mass extinction may have been less severe in marginal-marine settings. Ichnofaunas in pre- and post-extinction marginal-marine environments are remarkably similar and tend to be dominated by facies-crossing ichnotaxa (e.g., Diplocraterion , Palaeophycus , Planolites ) produced by opportunistic faunas.
-
from freshwater to fully marine exploring animal substrate interactions along a salinity gradient miocene oficina formation of venezuela
Palaeogeography Palaeoclimatology Palaeoecology, 2017Co-Authors: Euridice Solorzano, Luis A Buatois, Williams Rodriguez, Gabriela M ManganoAbstract:Abstract Venezuela has the largest hydrocarbon reserves in the world and most of these are within the Orinoco Oil Belt. The Oficina Formation of the Orinoco Oil Belt and the Oritupano Field comprises a wide range of environments formed under variable salinity conditions. These include freshwater fluvial and fluvio-tidal transition zones, brackish-water estuarine and delta-plain segments, alternating brackish-water and near-normal marine delta-front and prodelta settings, and normal-marine wave-dominated shoreface and offshore-shelf environments. The Oficina Formation thus provides an ideal opportunity to evaluate trace-fossil distribution and Ichnofacies gradients along a depositional profile and to calibrate salinity-related trace-fossil models. The Oficina Formation contains four softground Ichnofacies ( Scoyenia , depauperate Cruziana , Skolithos , and archetypal Cruziana ) and two substrate-controlled Ichnofacies ( Teredolites and Glossifungites ). Fluvial deposits in freshwater portions of tide-influenced, estuarine channels and distributary channels of tide-dominated deltas are locally intensely bioturbated, displaying low-diversity occurrences of the Scoyenia Ichnofacies. Brackish-water delta-plain and estuarine deposits display lower degrees of bioturbation and low ichnodiversity, as revealed by depauperate Cruziana Ichnofacies and the Skolithos Ichnofacies. Wave-dominated deltaic deposits display the Skolithos and the depauperate Cruziana Ichnofacies, but the presence of some ichnotaxa ( e.g. , Chondrites ) suggests periods of lower salinity stress, probably during times of reduced freshwater discharge. Open-marine deposits are characterized by intense bioturbation and very high diversity, as shown by the archetypal Cruziana Ichnofacies in low-energy distal settings, whereas high-energy proximal settings are characterized by the Skolithos Ichnofacies. Faunal distribution is strongly controlled by salinity, which makes trace-fossil evidence particularly useful for paleoenvironmental characterization of marginal-marine systems. In addition, the Glossifungites and Teredolites Ichnofacies indicate erosional exhumation of marginal-marine deposits, outlining transgressive surfaces of erosion. The Oficina Formation shows remarkable similarities in sedimentary facies and both trace-fossil and micropaleontological content with the Cretaceous McMurray Formation of western Canada.
-
integrated Ichnofacies models for deserts recurrent patterns and megatrends
Earth-Science Reviews, 2016Co-Authors: Veronica Krapovickas, Gabriela M Mangano, Luis A Buatois, Claudia Alicia MarsicanoAbstract:Abstract Although it is commonly assumed that the trace-fossil record of eolian dunes and associated environments is invariably poor, a systematic review of the available information indicates that this is not necessarily the case. A model involving five main phases of colonization of desert environments through the Phanerozoic is proposed in this paper. The first phase (Cambrian–Silurian) involved animal incursions into coastal dune fields directly from the sea, although it is unlikely that these animals would have remained for long periods of time in coastal deserts. The second phase (Devonian) reflects the activities of dune pioneers that left their fluvial habitat to enter temporary or permanently into inland deserts. The third phase (Carboniferous–Permian) involved the colonization of deserts by tetrapods. The fourth phase (Triassic–Cretaceous) involved a major exploitation of the infaunal ecospace as reflected by the appearance of more varied behavioral patterns in sub-superficial structures. The fifth phase (Paleogene–Recent) reflects the appearance of the ecological dynamic that characterizes modern desert communities. The invertebrate Ichnofacies for eolian dunes is re-named herein as the “Octopodichnus–Entradichnus Ichnofacies” honoring the seminal work of previous workers who simultaneously tackled the issue of eolian dune Ichnofacies. The Chelichnus Ichnofacies is retained for vertebrate trace-fossil assemblages in eolian settings. Both Ichnofacies occur in mobile and temporary stabilized sandy substrates, subject to frequent erosion and deposition, and to strong seasonality. Desert settings consist of complex mosaics of habitats or physical units associated with organism activity. Trace-fossil distribution can be understood as reflecting the partitioning of desert settings in a mosaic of landscape units, characterized by water content and its temporal fluctuations, nutrient availability, nature of the substrate, and the dominant organisms present. In turn, desert systems are dynamic entities that change as a response to regional climate. Landscape units, such as eolian sand seas, salt flat and playa lake systems, ephemeral rivers and alluvial fans, interact in response to regional-scale climate variations in hyper-arid, arid, and semiarid climatic settings. Ancient deserts completely developed under hyper-arid climatic conditions rarely preserve trace fossils due to the absence of moisture near the surface. However, the alternation of wet periods may represent windows for life development and thus, preservation of biogenic structures. Arid deserts display complex patterns of dunes combined with dry, wet, and flooded interdunes. Dry desert elements (e.g. dunes, interdunes, sand sheets) typically record the Entradichnus–Octopodichnus and Chelichnus Ichnofacies. Slight rises in regional precipitation produce elevation of the water table and increase of fluvial discharges that provide water and sediment to the system. These processes may result in the local concentration of trace fossils in wet interdunes and ephemeral fluvial systems, illustrating the Scoyenia and Chelichnus Ichnofacies. In semiarid systems playa lakes expand by the addition of freshwater, evolving into freshwater lakes, and fluvial systems may become more common; lake margins and fluvial overbanks typically contain trace-fossil assemblages that may be ascribed to the Scoyenia Ichnofacies.
-
trace fossils from carboniferous floodplain deposits in western argentina implications for Ichnofacies models of continental environments
Palaeogeography Palaeoclimatology Palaeoecology, 2002Co-Authors: Luis A Buatois, Gabriela M ManganoAbstract:Abstract Floodplain deposits from the Carboniferous Tupe Formation of western Argentina contain a low-diversity ichnofauna of invertebrates and plants. The assemblage consists of Archaeonassa fossulata, Didymaulichnus lyelli, Helminthoidichnites tenuis, Palaeophycus tubularis, Planolites isp., and root traces. This ichnofauna is characterized by the dominance of very simple forms, superficial or very shallow trace fossils, combination of locomotion, grazing, and dwelling structures, and production by arthropods and vermiform organisms. Primary sedimentary fabrics are disturbed only by plant trace fossils while animal trace fossils are mostly restricted to bedding surfaces, resulting in the virtual absence of bioturbation. The poorly-defined morphology of the ichnofossils, and the absence of backfilled striated trace fossils and structures indicative of subaerial exposure suggest subaqueous production. The envisaged depositional environment is a freshwater body developed in a floodplain and overfilled by overbank deposits. A review of floodplain ichnofaunas documented from the stratigraphic record indicates that two recurrent assemblages may be recognized. The first assemblage is characterized by low to rarely moderate diversity of invertebrate trace fossils, moderate to high diversity of vertebrate structures, and common presence of meniscate backfilled structures, bilobate trace fossils with scratch marks, arthropod trackways and tetrapod trackways. It is regarded as an example of the Scoyenia Ichnofacies developed in desiccated floodplains. The second type of floodplain assemblage, illustrated by the example documented in this paper, is characterized by grazing trails, locomotion trails and dwelling burrows, low to rarely moderate ichnodiversity, simple trace fossils, and superficial to very shallow structures. Although formed in floodplain environments also, this type of assemblage is remarkably different from the Scoyenia Ichnofacies. It is here regarded as an example of the Mermia Ichnofacies. Basic features of these ichnofaunas reflect subaqueous production of the assemblage. The lower ichnodiversity of these floodplain assemblages in comparison with their equivalents from lacustrine basins is probably an expression of the less stable conditions and temporary nature of floodplain water bodies. Our study supports the view that Ichnofacies are not indicators of sedimentary environments but reflect sets of environmental factors.
Luis A Buatois - One of the best experts on this subject based on the ideXlab platform.
-
trace fossils sedimentary facies and parasequence architecture from the lower cretaceous mulichinco formation of argentina the role of fair weather waves in shoreface deposits
Sedimentary Geology, 2018Co-Authors: Lindsey J N Wesolowski, Gabriela M Mangano, Luis A Buatois, Juan Jose Ponce, Noelia B CarmonaAbstract:Abstract Shorefaces can display strong facies variability and integration of sedimentology and ichnology provides a high-resolution model to identify variations among strongly storm-dominated (high energy), moderately storm-affected (intermediate energy), and weakly storm-affected (low energy) shoreface deposits. In addition, ichnology has proved to be of help to delineate parasequences as trace-fossil associations are excellent indicators of environmental conditions which typically change along the depositional profile. Shallow-marine deposits and associated ichnofaunas from the Mulichinco Formation (Valanginian, Lower Cretaceous) in Puerta Curaco, Neuquen Basin, western Argentina, were analyzed to evaluate stress factors on shoreface benthos and parasequence architecture. During storm-dominated conditions, the Skolithos Ichnofacies prevails within the offshore transition and lower shoreface represented by assemblages dominated by Thalassinoides isp. and Ophiomorpha irregulaire. Under weakly storm-affected conditions, the Cruziana Ichnofacies is recognized, characterized by assemblages dominated by Thalassinoides isp. and Gyrochorte comosa in the offshore transition, and by Gyrochorte comosa within the lower shoreface. Storm-influenced conditions yield wider ichnologic variability, showing elements of both Ichnofacies. Storm influence on sedimentation is affected by both allogenic (e.g. tectonic subsidence, sea-level, and sediment influx) and autogenic (e.g. hydrodynamic) controls at both parasequence and intra-parasequence scales. Four distinct types of parasequences were recognized, strongly storm-dominated, moderately storm-affected, moderately storm-affected – strongly fair-weather reworked, and weakly storm-affected, categorized based on parasequence architectural variability derived from varying degrees of storm and fair-weather wave influence. The new type of shoreface described here, the moderately storm-affected – strongly fair-weather reworked shoreface, features storm deposits reworked thoroughly by fair-weather waves. During fair-weather wave reworking, elements of the Cruziana Ichnofacies are overprinted upon relict elements of the Skolithos Ichnofacies from previous storm induced deposition. This type of shoreface, commonly overlooked in past literature, expands our understanding of the sedimentary dynamics and stratigraphic architecture in a shoreface susceptible to various parasequence and intra-parasequence scale degrees of storm and fair-weather wave influence.
-
Ichnology and depositional environments of the Upper Ordovician Stony Mountain Formation in the Williston Basin, Canada: Refining Ichnofacies and ichnofabric models for Epeiric Sea carbonates
Palaeogeography Palaeoclimatology Palaeoecology, 2018Co-Authors: Charlie Y.c. Zheng, M. Gabriela Mángano, Luis A BuatoisAbstract:Abstract Ordovician epeiric sea carbonates in intracratonic basins of Laurentia are enigmatic due to their unique depositional settings and the absence of modern analogs. Integrated ichnologic and sedimentologic analysis of the Upper Ordovician Stony Mountain Formation in the Williston Basin of Canada allows recognition of neritic-marine, nearshore-marine, open-lagoon, restricted-lagoon, peritidal sand-shoal and peritidal-flat subenvironments. The Cruziana Ichnofacies occurs in neritic (between fair-weather and storm wave bases) and nearshore (around fair-weather wave base) marine environments. The depauperate Cruziana Ichnofacies is present in open- and restricted-lagoon environments, indicating a shift from fully marine to stressed conditions. In the open lagoon, composite ichnofabrics related to omission surfaces illustrate the low rates of background sedimentation interrupted by event deposition and early cementation, illustrating the Glossifungites and Trypanites Ichnofacies. The decreased size of discrete burrows in the restricted lagoon is attributed to reduced oxygenation under stagnation rather than hypersalinity. The peritidal complex includes high-energy sand shoals and low-energy tidal flats. Only monospecific colonization took place sporadically in associated subtidal environments within the peritidal complex deposits.
-
early triassic estuarine depauperate cruziana Ichnofacies from the sichuan area of south china and its implications for the biotic recovery in brackish water settings after the end permian mass extinction
Palaeogeography Palaeoclimatology Palaeoecology, 2017Co-Authors: Lijun Zhang, Gabriela M Mangano, Luis A Buatois, Xin Zhang, Shangqian Sun, Chao TaiAbstract:Abstract New ichnological data from the Lower Triassic (Induan) Dongchuan Formation (Longmendong, South China) record the recovery interval of marginal-marine communities following the end-Permian mass extinction. Here, we document six ichnogenera from the upper part of the Dongchuan Formation of Dienerian (Early Triassic) age in the Longmendong area, Sichuan Province, South China. These are Cylindrichnus , Diplocraterion , Palaeophycus , Planolites , Siphonichnus , and Teichichnus , illustrating a depauperate Cruziana Ichnofacies. Facies analysis suggests that the depauperate Cruziana Ichnofacies is present in deposits recording the transition from fluvial to tide-dominated estuarine settings. Compilation of worldwide brackish-water ichnofaunas from Permian (average alpha ichnodiversity = 6.2) to Triassic (average alpha ichnodiversity = 5.5) suggests that no significant ichnodiversity decrease took place in these settings as a result of the mass extinction and further implies that the impact of the mass extinction may have been less severe in marginal-marine settings. Ichnofaunas in pre- and post-extinction marginal-marine environments are remarkably similar and tend to be dominated by facies-crossing ichnotaxa (e.g., Diplocraterion , Palaeophycus , Planolites ) produced by opportunistic faunas.
-
from freshwater to fully marine exploring animal substrate interactions along a salinity gradient miocene oficina formation of venezuela
Palaeogeography Palaeoclimatology Palaeoecology, 2017Co-Authors: Euridice Solorzano, Luis A Buatois, Williams Rodriguez, Gabriela M ManganoAbstract:Abstract Venezuela has the largest hydrocarbon reserves in the world and most of these are within the Orinoco Oil Belt. The Oficina Formation of the Orinoco Oil Belt and the Oritupano Field comprises a wide range of environments formed under variable salinity conditions. These include freshwater fluvial and fluvio-tidal transition zones, brackish-water estuarine and delta-plain segments, alternating brackish-water and near-normal marine delta-front and prodelta settings, and normal-marine wave-dominated shoreface and offshore-shelf environments. The Oficina Formation thus provides an ideal opportunity to evaluate trace-fossil distribution and Ichnofacies gradients along a depositional profile and to calibrate salinity-related trace-fossil models. The Oficina Formation contains four softground Ichnofacies ( Scoyenia , depauperate Cruziana , Skolithos , and archetypal Cruziana ) and two substrate-controlled Ichnofacies ( Teredolites and Glossifungites ). Fluvial deposits in freshwater portions of tide-influenced, estuarine channels and distributary channels of tide-dominated deltas are locally intensely bioturbated, displaying low-diversity occurrences of the Scoyenia Ichnofacies. Brackish-water delta-plain and estuarine deposits display lower degrees of bioturbation and low ichnodiversity, as revealed by depauperate Cruziana Ichnofacies and the Skolithos Ichnofacies. Wave-dominated deltaic deposits display the Skolithos and the depauperate Cruziana Ichnofacies, but the presence of some ichnotaxa ( e.g. , Chondrites ) suggests periods of lower salinity stress, probably during times of reduced freshwater discharge. Open-marine deposits are characterized by intense bioturbation and very high diversity, as shown by the archetypal Cruziana Ichnofacies in low-energy distal settings, whereas high-energy proximal settings are characterized by the Skolithos Ichnofacies. Faunal distribution is strongly controlled by salinity, which makes trace-fossil evidence particularly useful for paleoenvironmental characterization of marginal-marine systems. In addition, the Glossifungites and Teredolites Ichnofacies indicate erosional exhumation of marginal-marine deposits, outlining transgressive surfaces of erosion. The Oficina Formation shows remarkable similarities in sedimentary facies and both trace-fossil and micropaleontological content with the Cretaceous McMurray Formation of western Canada.
-
integrated Ichnofacies models for deserts recurrent patterns and megatrends
Earth-Science Reviews, 2016Co-Authors: Veronica Krapovickas, Gabriela M Mangano, Luis A Buatois, Claudia Alicia MarsicanoAbstract:Abstract Although it is commonly assumed that the trace-fossil record of eolian dunes and associated environments is invariably poor, a systematic review of the available information indicates that this is not necessarily the case. A model involving five main phases of colonization of desert environments through the Phanerozoic is proposed in this paper. The first phase (Cambrian–Silurian) involved animal incursions into coastal dune fields directly from the sea, although it is unlikely that these animals would have remained for long periods of time in coastal deserts. The second phase (Devonian) reflects the activities of dune pioneers that left their fluvial habitat to enter temporary or permanently into inland deserts. The third phase (Carboniferous–Permian) involved the colonization of deserts by tetrapods. The fourth phase (Triassic–Cretaceous) involved a major exploitation of the infaunal ecospace as reflected by the appearance of more varied behavioral patterns in sub-superficial structures. The fifth phase (Paleogene–Recent) reflects the appearance of the ecological dynamic that characterizes modern desert communities. The invertebrate Ichnofacies for eolian dunes is re-named herein as the “Octopodichnus–Entradichnus Ichnofacies” honoring the seminal work of previous workers who simultaneously tackled the issue of eolian dune Ichnofacies. The Chelichnus Ichnofacies is retained for vertebrate trace-fossil assemblages in eolian settings. Both Ichnofacies occur in mobile and temporary stabilized sandy substrates, subject to frequent erosion and deposition, and to strong seasonality. Desert settings consist of complex mosaics of habitats or physical units associated with organism activity. Trace-fossil distribution can be understood as reflecting the partitioning of desert settings in a mosaic of landscape units, characterized by water content and its temporal fluctuations, nutrient availability, nature of the substrate, and the dominant organisms present. In turn, desert systems are dynamic entities that change as a response to regional climate. Landscape units, such as eolian sand seas, salt flat and playa lake systems, ephemeral rivers and alluvial fans, interact in response to regional-scale climate variations in hyper-arid, arid, and semiarid climatic settings. Ancient deserts completely developed under hyper-arid climatic conditions rarely preserve trace fossils due to the absence of moisture near the surface. However, the alternation of wet periods may represent windows for life development and thus, preservation of biogenic structures. Arid deserts display complex patterns of dunes combined with dry, wet, and flooded interdunes. Dry desert elements (e.g. dunes, interdunes, sand sheets) typically record the Entradichnus–Octopodichnus and Chelichnus Ichnofacies. Slight rises in regional precipitation produce elevation of the water table and increase of fluvial discharges that provide water and sediment to the system. These processes may result in the local concentration of trace fossils in wet interdunes and ephemeral fluvial systems, illustrating the Scoyenia and Chelichnus Ichnofacies. In semiarid systems playa lakes expand by the addition of freshwater, evolving into freshwater lakes, and fluvial systems may become more common; lake margins and fluvial overbanks typically contain trace-fossil assemblages that may be ascribed to the Scoyenia Ichnofacies.
George S Pemberton - One of the best experts on this subject based on the ideXlab platform.
-
the ichnological and sedimentological signature of a late paleozoic postglacial marginal marine and shallow marine tidally influenced setting the wudayhi member of the nuayyim formation unayzah group in the subsurface of central and eastern saudi arabia
Journal of Sedimentary Research, 2018Co-Authors: Camilo A Polo, Murray K. Gingras, John Melvin, Nigel P Hooker, Andrew J Rees, George S PembertonAbstract:Abstract Sedimentation in the Nuayyim Formation across subsurface central and eastern Saudi Arabia has been chiefly ascribed to continental sedimentary environments. However, a number of levels in this formation show evidence for marginal-marine and shallow-marine sedimentation. This paper documents trace-fossil faunas and sedimentological characteristics from these facies and presents a regional depositional model for the Wudayhi Member that confirms the presence of shallow-marine sedimentary environments. Marginal-marine and shallow-marine sedimentation in the Wudayhi Member includes estuarine deposits and upper-shoreface through lower-shoreface deposits. They are reflective of several transgressive–regressive (T-R) cycles in an overall shoaling-upwards, tidally influenced progradational succession that exhibit mixed-process (wave-, tide-, and fluvially-influenced) depositional environments. The succession displays an overall upward decrease in bioturbation intensity with elements of an impoverished proximal expression of the Cruziana Ichnofacies at the base in proximal- and distal- lower-shoreface deposits (Facies 5–6), passing into an impoverished expression of the Skolithos Ichnofacies in upper-shoreface deposits (Facies 4). Therein, Facies 5 records storm-influenced sedimentation and includes hummocky cross-stratification (HCS), combined-flow ripples, cross-lamination, and ichnofossils that alternate between storm-related and fair-weather assemblages. An overall reduction in both the diversity of ichnogenera and the intensity of burrowing across the shoreface profile, an apparent lack of middle-shoreface deposits, and the occurrence of storm-wave-generated structures interspersed with tidally generated structures in the center and southeast of the study area are interpreted as tidal modulation, suggesting macrotidal conditions at the time of sediment deposition. Estuarine sedimentation includes coal deposits (Facies 1), tidal flats (Facies 2), and fluvio-tidal deposits (Facies 3) that overlie the succession, and display a stressed, impoverished mixture of traces with facies-crossing elements of the Skolithos and Cruziana Ichnofacies in the north and northwest of the study area. Sedimentation took place on a broad and sandy, partially restricted shelf, chiefly influenced by tidal currents that was variably fluvially influenced. The interplay of the aforementioned processes results in a complex architecture that is traceable, based on the sedimentological and ichnological content. Colonization by bioturbating infauna exhibiting elements of an overall impoverished Skolithos and Cruziana Ichnofacies in the Wudayhi Member is interpreted to be related to sea-level rise, with regional transgression induced by the melting of glacier ice following the Late Carboniferous to Early Permian glaciation that affected southern Gondwana. Subsequently, as the Arabian Plate migrated northwards, isostatic rebound concomitant with increased tectonism associated with the Neotethys propagating into the Arabian Peninsula caused regional regression responsible for the progradational sequence presented herein in the Early to Middle Permian. Trace-fossil associations and Ichnofacies presented in this paper are significant, because they provide evidence for marginal-marine and shallow-marine tide- and storm-influenced processes in the Unayzah Group during deposition of the Wudayhi Member of the Nuayyim Formation. Furthermore, it establishes a framework than can be linked to fully marine coeval deposits southeastern of the Arabian Peninsula into Oman.
-
the glossifungites Ichnofacies and sequence stratigraphic analysis a case study from middle to upper eocene successions in fayum egypt
Ichnos-an International Journal for Plant and Animal Traces, 2016Co-Authors: Zaki A Abdelfattah, Murray K. Gingras, Michael W Caldwell, George S Pemberton, James A. MaceachernAbstract:ABSTRACTThe Glossifungites Ichnofacies was erected by Dolf Seilacher (the father of modern ichnology) in the mid-nineteen sixties to encompass burrows excavated into firm or compacted substrates. Correspondingly, this firmground Ichnofacies has been used extensively in the identification of omission surfaces and the identification and interpretation of sequence stratigraphic discontinuities. A case study from Eocene strata in the Fayum depression of Egypt presents an opportunity to showcase a genetic approach for classifying occurrences of the Glossifungites Ichnofacies. More than twenty-five Glossifungites Ichnofacies–demarcated surfaces are documented and examined in this study. Based on the origin and character of these discontinuities, the examined surfaces are grouped into two main types: those of autogenic origin and those of allogenic derivation. The allogenically generated expressions of the Glossifungites Ichnofacies are associated with key-stratigraphic discontinuities of sequence stratigraphic ...
-
an example of a highly bioturbated storm influenced shoreface deposit upper jurassic ula formation norwegian north sea
Sedimentology, 2014Co-Authors: Greg M Baniak, Murray K. Gingras, Beverly A Burns, George S PembertonAbstract:Integrated ichnological and sedimentological analyses of core samples from the Upper Jurassic Ula Formation in the Norwegian Central Graben were undertaken to quantify the influence of storm waves on sedimentation. Two main facies associations (offshore and shoreface) that form a progradational coarsening upward succession are recognizable within the cores. The offshore deposits are characterized by massive to finely laminated mudstones and fine-grained sandstones, within a moderately to highly bioturbated complex. The trace fossil assemblage is dominated by deposit-feeding structures (for example, Planolites, Phycosiphon and Rosselia) and constitutes an expression of the proximal Zoophycos to distal Cruziana Ichnofacies. The absence of grazing behaviours and dominance of deposit-feeding ichnofossils is a reflection of the increased wave energies present (i.e. storm-generated currents) within an offshore setting. The shoreface succession is represented by highly bioturbated fine-grained to medium-grained sandstones, with intervals of planar and trough cross-bedding, thin pebble lags and bivalve-rich shell layers. The ichnofossil assemblage, forming part of the Skolithos Ichnofacies, is dominated by higher energy Ophiomorpha nodosa ichnofossils and lower energy Ophiomorpha irregulaire and Siphonichnus ichnofossils. The presence of sporadic wave-generated sedimentary structures and variability in ichnofossil diversity and abundance attests to the influence of storm-generated currents during deposition. As a whole, the Ula Formation strongly reflects the influence of storm deposits on sediment deposition; consequently, storm-influenced shoreface most accurately describes these depositional environments.
-
the Ichnofacies paradigm
Developments in sedimentology, 2012Co-Authors: James A. Maceachern, Murray K. Gingras, Shahin E. Dashtgard, Kerrie L. Bann, Johnpaul Zonneveld, George S PembertonAbstract:Abstract The Ichnofacies paradigm has evolved over a six-decade period since its original inception by Dolf Seilacher. It is a multidimensional framework underpinned by recurring, facies-controlled groupings of biogenic structures that reflect animal responses to paleoenvironmental conditions. These constitute spatially and temporally extensive associations commonly regarded as “Seilacherian Ichnofacies.” The marine realm hosts five recurring softground Ichnofacies (Psilonichnus, Skolithos, Cruziana, Zoophycos, and Nereites), generally distributed in a proximal–distal trend reflecting a passive response to increasing water depth (i.e., controlled by depositional factors that progressively change with bathymetry). There are three substrate-controlled Ichnofacies (Trypanites, Teredolites, and Glossifungites), recording organism occupation of palimpsest substrates. Finally, there are six continental Ichnofacies (Scoyenia, Mermia, Coprinisphaera, Termitichnus, Celliforma, and Octopodichnus–Entradichnus), mainly recording organism responses to temperature and the availability of moisture (i.e., climate-driven associations) in terrestrial settings or oxygenation, depositional energy, and substrate consistency in subaqueous settings. The Seilacherian Ichnofacies operate as facies models, built through the distillation of ichnological characteristics derived from numerous modern and ancient case studies. Like lithofacies models, they serve as a norm for comparison, a framework for observations, a predictor in new situations, an integrated basis for interpretation, and a basis for teaching and communication.
-
autogenic occurrence of glossifungites Ichnofacies examples from wave dominated macrotidal flats southwestern coast of korea
Marine Geology, 2009Co-Authors: Byongcheon Yang, Murray K. Gingras, Robert W Dalrymple, George S PembertonAbstract:Abstract Firmground muds are frequently exposed on the high-tide beach face in the zone of maximum wave energy on the wave-dominated tidal flats along the southwestern coast of Korea. The firmground muds typically display open, unlined burrows, dominated by incipient Psilonichnus and Thalassinoides that cross-cut the earlier-formed softground suites, which comprise Skolithos , Arenicolites and Monocraterion . Modern faunal distributions confirm that these ichnogenera are constructed in sediments of different consistency at the time of colonization as a result of autogenic swash-bar migration. By considering the migration-rate of the intertidal swash bars, it can be shown that the mud only needs to be buried as little as 0.5 m for a few years to produce the firmground muds. These numbers for burial depth and duration are much less than is commonly realized. The results of this research, combined with previous studies, suggest that the Glossifungites Ichnofacies is environmentally wide-ranging from tide-dominated to wave-dominated settings. This study also confirms that the Glossifungites Ichnofacies is mainly associated with erosion in marginal-marine settings and can thereby be deployed as a stratigraphic indicator of hiatal surfaces. However, the stratigraphic importance of Glossifungites -demarcated discontinuities must be assessed carefully to determine whether or not allogenic or autogenic processes contributed to their emplacement.
Euridice Solorzano - One of the best experts on this subject based on the ideXlab platform.
-
from freshwater to fully marine exploring animal substrate interactions along a salinity gradient miocene oficina formation of venezuela
Palaeogeography Palaeoclimatology Palaeoecology, 2017Co-Authors: Euridice Solorzano, Luis A Buatois, Williams Rodriguez, Gabriela M ManganoAbstract:Abstract Venezuela has the largest hydrocarbon reserves in the world and most of these are within the Orinoco Oil Belt. The Oficina Formation of the Orinoco Oil Belt and the Oritupano Field comprises a wide range of environments formed under variable salinity conditions. These include freshwater fluvial and fluvio-tidal transition zones, brackish-water estuarine and delta-plain segments, alternating brackish-water and near-normal marine delta-front and prodelta settings, and normal-marine wave-dominated shoreface and offshore-shelf environments. The Oficina Formation thus provides an ideal opportunity to evaluate trace-fossil distribution and Ichnofacies gradients along a depositional profile and to calibrate salinity-related trace-fossil models. The Oficina Formation contains four softground Ichnofacies ( Scoyenia , depauperate Cruziana , Skolithos , and archetypal Cruziana ) and two substrate-controlled Ichnofacies ( Teredolites and Glossifungites ). Fluvial deposits in freshwater portions of tide-influenced, estuarine channels and distributary channels of tide-dominated deltas are locally intensely bioturbated, displaying low-diversity occurrences of the Scoyenia Ichnofacies. Brackish-water delta-plain and estuarine deposits display lower degrees of bioturbation and low ichnodiversity, as revealed by depauperate Cruziana Ichnofacies and the Skolithos Ichnofacies. Wave-dominated deltaic deposits display the Skolithos and the depauperate Cruziana Ichnofacies, but the presence of some ichnotaxa ( e.g. , Chondrites ) suggests periods of lower salinity stress, probably during times of reduced freshwater discharge. Open-marine deposits are characterized by intense bioturbation and very high diversity, as shown by the archetypal Cruziana Ichnofacies in low-energy distal settings, whereas high-energy proximal settings are characterized by the Skolithos Ichnofacies. Faunal distribution is strongly controlled by salinity, which makes trace-fossil evidence particularly useful for paleoenvironmental characterization of marginal-marine systems. In addition, the Glossifungites and Teredolites Ichnofacies indicate erosional exhumation of marginal-marine deposits, outlining transgressive surfaces of erosion. The Oficina Formation shows remarkable similarities in sedimentary facies and both trace-fossil and micropaleontological content with the Cretaceous McMurray Formation of western Canada.
Murray K. Gingras - One of the best experts on this subject based on the ideXlab platform.
-
the ichnological and sedimentological signature of a late paleozoic postglacial marginal marine and shallow marine tidally influenced setting the wudayhi member of the nuayyim formation unayzah group in the subsurface of central and eastern saudi arabia
Journal of Sedimentary Research, 2018Co-Authors: Camilo A Polo, Murray K. Gingras, John Melvin, Nigel P Hooker, Andrew J Rees, George S PembertonAbstract:Abstract Sedimentation in the Nuayyim Formation across subsurface central and eastern Saudi Arabia has been chiefly ascribed to continental sedimentary environments. However, a number of levels in this formation show evidence for marginal-marine and shallow-marine sedimentation. This paper documents trace-fossil faunas and sedimentological characteristics from these facies and presents a regional depositional model for the Wudayhi Member that confirms the presence of shallow-marine sedimentary environments. Marginal-marine and shallow-marine sedimentation in the Wudayhi Member includes estuarine deposits and upper-shoreface through lower-shoreface deposits. They are reflective of several transgressive–regressive (T-R) cycles in an overall shoaling-upwards, tidally influenced progradational succession that exhibit mixed-process (wave-, tide-, and fluvially-influenced) depositional environments. The succession displays an overall upward decrease in bioturbation intensity with elements of an impoverished proximal expression of the Cruziana Ichnofacies at the base in proximal- and distal- lower-shoreface deposits (Facies 5–6), passing into an impoverished expression of the Skolithos Ichnofacies in upper-shoreface deposits (Facies 4). Therein, Facies 5 records storm-influenced sedimentation and includes hummocky cross-stratification (HCS), combined-flow ripples, cross-lamination, and ichnofossils that alternate between storm-related and fair-weather assemblages. An overall reduction in both the diversity of ichnogenera and the intensity of burrowing across the shoreface profile, an apparent lack of middle-shoreface deposits, and the occurrence of storm-wave-generated structures interspersed with tidally generated structures in the center and southeast of the study area are interpreted as tidal modulation, suggesting macrotidal conditions at the time of sediment deposition. Estuarine sedimentation includes coal deposits (Facies 1), tidal flats (Facies 2), and fluvio-tidal deposits (Facies 3) that overlie the succession, and display a stressed, impoverished mixture of traces with facies-crossing elements of the Skolithos and Cruziana Ichnofacies in the north and northwest of the study area. Sedimentation took place on a broad and sandy, partially restricted shelf, chiefly influenced by tidal currents that was variably fluvially influenced. The interplay of the aforementioned processes results in a complex architecture that is traceable, based on the sedimentological and ichnological content. Colonization by bioturbating infauna exhibiting elements of an overall impoverished Skolithos and Cruziana Ichnofacies in the Wudayhi Member is interpreted to be related to sea-level rise, with regional transgression induced by the melting of glacier ice following the Late Carboniferous to Early Permian glaciation that affected southern Gondwana. Subsequently, as the Arabian Plate migrated northwards, isostatic rebound concomitant with increased tectonism associated with the Neotethys propagating into the Arabian Peninsula caused regional regression responsible for the progradational sequence presented herein in the Early to Middle Permian. Trace-fossil associations and Ichnofacies presented in this paper are significant, because they provide evidence for marginal-marine and shallow-marine tide- and storm-influenced processes in the Unayzah Group during deposition of the Wudayhi Member of the Nuayyim Formation. Furthermore, it establishes a framework than can be linked to fully marine coeval deposits southeastern of the Arabian Peninsula into Oman.
-
the glossifungites Ichnofacies and sequence stratigraphic analysis a case study from middle to upper eocene successions in fayum egypt
Ichnos-an International Journal for Plant and Animal Traces, 2016Co-Authors: Zaki A Abdelfattah, Murray K. Gingras, Michael W Caldwell, George S Pemberton, James A. MaceachernAbstract:ABSTRACTThe Glossifungites Ichnofacies was erected by Dolf Seilacher (the father of modern ichnology) in the mid-nineteen sixties to encompass burrows excavated into firm or compacted substrates. Correspondingly, this firmground Ichnofacies has been used extensively in the identification of omission surfaces and the identification and interpretation of sequence stratigraphic discontinuities. A case study from Eocene strata in the Fayum depression of Egypt presents an opportunity to showcase a genetic approach for classifying occurrences of the Glossifungites Ichnofacies. More than twenty-five Glossifungites Ichnofacies–demarcated surfaces are documented and examined in this study. Based on the origin and character of these discontinuities, the examined surfaces are grouped into two main types: those of autogenic origin and those of allogenic derivation. The allogenically generated expressions of the Glossifungites Ichnofacies are associated with key-stratigraphic discontinuities of sequence stratigraphic ...
-
trypanites type Ichnofacies at the bay of fundy nova scotia canada
PALAIOS, 2015Co-Authors: Carolyn M Furlong, Murray K. Gingras, Johnpaul ZonneveldAbstract:ABSTRACT The Trypanites Ichnofacies is frequently associated with low biotic and trace diversity, and erosional or nondepositional conditions. However, analysis of an extensively exposed, modern, siliciclastic, intertidal hardground community near Thomas Cove, located at Economy Point, Nova Scotia, within the Bay of Fundy, reveals a diverse community of boring, encrusting, and squatting/clinging organisms and a diverse assemblage of sedimentary structures. A high diversity of biota and low diversity, but high abundance, of borings is present along this modern Trypanites-type Ichnofacies. Species richness reaches 37 organisms within the study area, and two boring bivalves (Petricola pholadiformis and Zirfaea pilsbryi), which produce Gastrochaenolites-like traces, are present. Eleven distinct depositional subenvironments are identified and are categorized as being either Trypanites-bearing or Trypanites-barren. Analysis of this modern analogue suggests that ancient Trypanites Ichnofacies may have been more ...
-
an example of a highly bioturbated storm influenced shoreface deposit upper jurassic ula formation norwegian north sea
Sedimentology, 2014Co-Authors: Greg M Baniak, Murray K. Gingras, Beverly A Burns, George S PembertonAbstract:Integrated ichnological and sedimentological analyses of core samples from the Upper Jurassic Ula Formation in the Norwegian Central Graben were undertaken to quantify the influence of storm waves on sedimentation. Two main facies associations (offshore and shoreface) that form a progradational coarsening upward succession are recognizable within the cores. The offshore deposits are characterized by massive to finely laminated mudstones and fine-grained sandstones, within a moderately to highly bioturbated complex. The trace fossil assemblage is dominated by deposit-feeding structures (for example, Planolites, Phycosiphon and Rosselia) and constitutes an expression of the proximal Zoophycos to distal Cruziana Ichnofacies. The absence of grazing behaviours and dominance of deposit-feeding ichnofossils is a reflection of the increased wave energies present (i.e. storm-generated currents) within an offshore setting. The shoreface succession is represented by highly bioturbated fine-grained to medium-grained sandstones, with intervals of planar and trough cross-bedding, thin pebble lags and bivalve-rich shell layers. The ichnofossil assemblage, forming part of the Skolithos Ichnofacies, is dominated by higher energy Ophiomorpha nodosa ichnofossils and lower energy Ophiomorpha irregulaire and Siphonichnus ichnofossils. The presence of sporadic wave-generated sedimentary structures and variability in ichnofossil diversity and abundance attests to the influence of storm-generated currents during deposition. As a whole, the Ula Formation strongly reflects the influence of storm deposits on sediment deposition; consequently, storm-influenced shoreface most accurately describes these depositional environments.
-
Computer modeling bioturbation: The creation of porous and permeable fluid-flow pathways
AAPG Bulletin, 2012Co-Authors: Andrew D. La Croix, Murray K. Gingras, Shahin E. Dashtgard, S. George PembertonAbstract:Computer modeling of trace fossils (Skolithos, Thalassinoides, Planolites, Zoophycos, and Phycosiphon) and Ichnofacies (Skolithos, Cruziana, and Zoophycos Ichnofacies) is undertaken to assess the impact of bioturbation on porosity and permeability trends in sedimentary media. Model volumes are randomly populated with the digitally modeled trace fossils to test for connectivity between burrows. The probability of vertical and lateral interconnections is compared with bioturbation intensity. The results of the simulations indicate that biogenic flow networks develop at low bioturbation intensity, between 10 and 27.5% bioturbation (BI-2). However, the efficiency of connectivity is controlled by the architecture of the burrows. For all trace-fossil and Ichnofacies models, regardless of trace-fossil orientation, continuous horizontal and vertical connectivity across the sediment volume is achieved within a 0 to 10% range in bioturbation. In subsurface aquifers and petroleum reservoirs, the presence of bioturbation can significantly influence fluid flow. In particular, for marine sedimentary rocks, where burrows are more permeable than the surrounding matrix, a greater degree of three-dimensional burrow connectivity can produce preferred fluid-flow pathways through the rock. Recognizing these flow conduits may enable optimization of resource exploitation or may contribute to increasing reserve estimates from previously interpreted nonreservoir rock.
