In the past decades it has become evident that the often cyclic cross-shore migration of longshore bars is significantly influenced by wave climate. This study demonstrates that this cyclic migration, whether landward or seaward, leads to the formation of low-angle seaward-inclined stratification (SIS) spanning the beach and upper shoreface in ground-penetrating radar (GPR) data from prograding sandy coastal barriers including strandplains. Previously documented radargrams of these systems are reinterpreted using this knowledge of cross-shore dynamics of longshore bars. Five distinct wave-climate-related radar architectures are identified.A notable observation is the prevalence of SIS as the dominant upper-shoreface to beach structure in most radargrams, despite its infrequently described occurrence from outcrop observations. To address this disparity, this paper also focuses on recognizing SIS in outcrop and core data. Compelling evidence of SIS was discovered in a late Messinian coastal barrier parasequence in SE Spain, and the associated sedimentary architecture is described in detail. It is hypothesized that this example holds generic significance, illustrated using core data from Middle Jurassic strata of the Norwegian continental shelf, and suggesting that the sedimentary architectures of numerous other ancient prograding barrier deposits may exhibit variations within a similar SIS framework.
{"title":"Recognition of cross-shore dynamics of longshore bars in upper-shoreface deposits of prograding sandy coastal barriers","authors":"Jan H. van den Berg, Allard W. Martinius","doi":"10.2110/jsr.2023.116","DOIUrl":"https://doi.org/10.2110/jsr.2023.116","url":null,"abstract":"In the past decades it has become evident that the often cyclic cross-shore migration of longshore bars is significantly influenced by wave climate. This study demonstrates that this cyclic migration, whether landward or seaward, leads to the formation of low-angle seaward-inclined stratification (SIS) spanning the beach and upper shoreface in ground-penetrating radar (GPR) data from prograding sandy coastal barriers including strandplains. Previously documented radargrams of these systems are reinterpreted using this knowledge of cross-shore dynamics of longshore bars. Five distinct wave-climate-related radar architectures are identified.A notable observation is the prevalence of SIS as the dominant upper-shoreface to beach structure in most radargrams, despite its infrequently described occurrence from outcrop observations. To address this disparity, this paper also focuses on recognizing SIS in outcrop and core data. Compelling evidence of SIS was discovered in a late Messinian coastal barrier parasequence in SE Spain, and the associated sedimentary architecture is described in detail. It is hypothesized that this example holds generic significance, illustrated using core data from Middle Jurassic strata of the Norwegian continental shelf, and suggesting that the sedimentary architectures of numerous other ancient prograding barrier deposits may exhibit variations within a similar SIS framework.","PeriodicalId":17044,"journal":{"name":"Journal of Sedimentary Research","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141743109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
E. Garzanti, G. Bayon, M. Barbarano, A. Resentini, G. Vezzoli, G. Pastore, Mathilde Levacher, O. Adeaga
This study explores in detail the complexity of textural/compositional relationships in fluvial sediments. To this aim, fifteen size fractions (from clay to granule) of three sediment samples characterized by virtually identical size distribution from the Niger and Benue rivers in central Nigeria were separately analysed by multiple methods (optical microscopy, manual and semi-automated Raman spectroscopy, X-ray diffraction, elemental geochemistry, Nd isotopes). The independent mineralogical and geochemical datasets thus obtained allowed us to investigate processes of sediment generation for five diverse size modes (clay, fine cohesive silt, very coarse frictional silt, very fine sand, coarse sand) derived in different proportions from different sources (wind-blown dust, soils and paleosols, fine-grained and coarse-grained siliciclastic units, igneous and metamorphic bedrocks). Controls on the size distribution of detrital minerals (settling equivalence, size inheritance, weathering, mechanical durabil ity, and chemical durability through multiple sedimentary cycles) were examined, specifically focusing on tectosilicates and on the long-standing petrological problem of feldspar-grain size relations. Different factors determine the composition of different size modes: kaolinite-dominated clay derives from both deeply weathered soils or paleosols and distant Saharan sources; cohesive silt is largely recycled from soils formed in sedimentary basins. The proportion of detritus derived first-cycle from basement rocks increases from very coarse silt to very fine sand, whereas the coarse sand mode is quartz-dominated with minor plagioclase and amphibole and local occurrence of garnet, staurolite, monazite, or xenotime reflecting a combined influence of size inheritance from igneous (pegmatite) and metamorphic sources, mechanical and chemical durability, and recycling from coarse-grained siliciclastic units. Sediment budgets based on mineralogical, geochemical, and geochronological signatures consistently indicate dominance of Benue sediment supply, although contributions from the Niger mainstem to the Niger Delta are inferred to have been notably greater in the wetter past, before clastic fluxes dropped in response to the aridification of the Sahel.
{"title":"Anatomy of Niger and Benue river sediments from clay to granule: grain-size dependence and provenance budgets","authors":"E. Garzanti, G. Bayon, M. Barbarano, A. Resentini, G. Vezzoli, G. Pastore, Mathilde Levacher, O. Adeaga","doi":"10.2110/jsr.2024.024","DOIUrl":"https://doi.org/10.2110/jsr.2024.024","url":null,"abstract":"This study explores in detail the complexity of textural/compositional relationships in fluvial sediments. To this aim, fifteen size fractions (from clay to granule) of three sediment samples characterized by virtually identical size distribution from the Niger and Benue rivers in central Nigeria were separately analysed by multiple methods (optical microscopy, manual and semi-automated Raman spectroscopy, X-ray diffraction, elemental geochemistry, Nd isotopes). The independent mineralogical and geochemical datasets thus obtained allowed us to investigate processes of sediment generation for five diverse size modes (clay, fine cohesive silt, very coarse frictional silt, very fine sand, coarse sand) derived in different proportions from different sources (wind-blown dust, soils and paleosols, fine-grained and coarse-grained siliciclastic units, igneous and metamorphic bedrocks). Controls on the size distribution of detrital minerals (settling equivalence, size inheritance, weathering, mechanical durabil ity, and chemical durability through multiple sedimentary cycles) were examined, specifically focusing on tectosilicates and on the long-standing petrological problem of feldspar-grain size relations. Different factors determine the composition of different size modes: kaolinite-dominated clay derives from both deeply weathered soils or paleosols and distant Saharan sources; cohesive silt is largely recycled from soils formed in sedimentary basins. The proportion of detritus derived first-cycle from basement rocks increases from very coarse silt to very fine sand, whereas the coarse sand mode is quartz-dominated with minor plagioclase and amphibole and local occurrence of garnet, staurolite, monazite, or xenotime reflecting a combined influence of size inheritance from igneous (pegmatite) and metamorphic sources, mechanical and chemical durability, and recycling from coarse-grained siliciclastic units. Sediment budgets based on mineralogical, geochemical, and geochronological signatures consistently indicate dominance of Benue sediment supply, although contributions from the Niger mainstem to the Niger Delta are inferred to have been notably greater in the wetter past, before clastic fluxes dropped in response to the aridification of the Sahel.","PeriodicalId":17044,"journal":{"name":"Journal of Sedimentary Research","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141829086","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ibrahim Tinni Tahiru, Peter M. Burgess, Christopher Stevenson
Submarine fan strata are commonly described and interpreted assuming a nested, hierarchical organisation of elements, from beds to lobe elements, lobes and lobe complexes. However, describing outcrop and subsurface strata following a particular conceptual method or model is rarely evidence that the model or method accurately reflects the true nature of the strata. To develop more robust understanding of hierarchy in submarine fan strata we developed two metrics, a clustering strength metric that measures how much clustering is present in the spatial distribution of beds, and a hierarchy step metric that indicates how many clustered hierarchical elements are present in the bed spatial distribution. Both metrics are applied to two quantitative fan models. The first model is a very simple geometric model with 10 realisations ranging from a perfectly clustered hierarchy to an indistinguishable-from-random arrangement of beds. The second model, Lobyte3D, is a reduced-complexity process model which uses a st eepest descent flow routing algorithm, combined with a simple but physically reasonable representation of flow velocity, erosion, transport and deposition thresholds, to generate detailed 3D representations of submarine fan strata. Application of the cluster strength and hierarchy step metric to the simpler model demonstrates how the metrics usefully characterise how much order and hierarchy is present in the fan strata. Application to four Lobyte3D models with increasingly complex basin-floor topography shows no evidence for true hierarchy, despite clear self-organisation of the model strata into lobes, suggesting that either Lobyte3D is missing key currently unidentified processes responsible for producing hierarchy, or that interpretations of hierarchy in submarine fan strata are not realistic.
{"title":"Deep-Water Fan Hierarchy: Assumptions, Evidence, and Numerical Modelling Analysis","authors":"Ibrahim Tinni Tahiru, Peter M. Burgess, Christopher Stevenson","doi":"10.2110/jsr.2023.130","DOIUrl":"https://doi.org/10.2110/jsr.2023.130","url":null,"abstract":"Submarine fan strata are commonly described and interpreted assuming a nested, hierarchical organisation of elements, from beds to lobe elements, lobes and lobe complexes. However, describing outcrop and subsurface strata following a particular conceptual method or model is rarely evidence that the model or method accurately reflects the true nature of the strata. To develop more robust understanding of hierarchy in submarine fan strata we developed two metrics, a clustering strength metric that measures how much clustering is present in the spatial distribution of beds, and a hierarchy step metric that indicates how many clustered hierarchical elements are present in the bed spatial distribution. Both metrics are applied to two quantitative fan models. The first model is a very simple geometric model with 10 realisations ranging from a perfectly clustered hierarchy to an indistinguishable-from-random arrangement of beds. The second model, Lobyte3D, is a reduced-complexity process model which uses a st eepest descent flow routing algorithm, combined with a simple but physically reasonable representation of flow velocity, erosion, transport and deposition thresholds, to generate detailed 3D representations of submarine fan strata. Application of the cluster strength and hierarchy step metric to the simpler model demonstrates how the metrics usefully characterise how much order and hierarchy is present in the fan strata. Application to four Lobyte3D models with increasingly complex basin-floor topography shows no evidence for true hierarchy, despite clear self-organisation of the model strata into lobes, suggesting that either Lobyte3D is missing key currently unidentified processes responsible for producing hierarchy, or that interpretations of hierarchy in submarine fan strata are not realistic.","PeriodicalId":17044,"journal":{"name":"Journal of Sedimentary Research","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141828810","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The deposits of flood- and earthquake-derived subaqueous sediment gravity flows represent a significant fraction of lacustrine and deep-sea sedimentary successions, thus providing a valuable record of such natural disasters. The magnitude of these events and the thickness of the associated deposits are considered to follow a lognormal or power-law frequency distribution, whilst that of time intervals between subsequent events appear to be best approximated by a Poisson model, indicative of a random, time-independent phenomenon. However, the debate on whether the sedimentary record of these natural disasters is governed by randomness alone or whether there is some underlying stratigraphic ordering is still unsettled and requires detailed time-series analysis. This study consists of a time-series analysis of mudstone- and sandstone-dominated turbidite successions offshore a fan-delta system in the Neogene Aoshima Formation that belongs to the sedimentary fill of the forearc basin of southwest Japan. The formation consists of a monotonous alternation of very fine- to medium-grained sandstones capped by hemipelagic mudstones and, more rarely, by turbidite mudstones. The results show that the autocorrelation function of the time series suggests quasi-periodic variability in the upper sandstone-dominated part, whereas the lower mudstone-dominated part shows a white-noise-like pattern. Rescaled range analysis shows that the number of events per unit time in the lower part is characterized by a random time series, such as Brownian noise with a Hurst exponent of 0.5. In contrast, the thickness of event beds of the lower part and the thickness and the number of events of the upper part are persistent time series with a Hurst exponent > 0.5. These results suggest that the number of turbidite depositional events in the mudstone-dominated part indicates random timing, whereas its thickness time series and the sandstone-dominant part are not governed by simple stochastic processes but are affected by sea-level changes, sediment transport dynamics, and other factors such as, for example, seafloor topography.
{"title":"Random and time-persistent depositional processes in turbidite successions: an example from the marine deep-water Aoshima Formation (Neogene, Kyushu Island, southwest Japan)","authors":"Yoshiro Ishihara, Keisuke Kimata, Yuri Onishi","doi":"10.2110/jsr.2022.067","DOIUrl":"https://doi.org/10.2110/jsr.2022.067","url":null,"abstract":"The deposits of flood- and earthquake-derived subaqueous sediment gravity flows represent a significant fraction of lacustrine and deep-sea sedimentary successions, thus providing a valuable record of such natural disasters. The magnitude of these events and the thickness of the associated deposits are considered to follow a lognormal or power-law frequency distribution, whilst that of time intervals between subsequent events appear to be best approximated by a Poisson model, indicative of a random, time-independent phenomenon. However, the debate on whether the sedimentary record of these natural disasters is governed by randomness alone or whether there is some underlying stratigraphic ordering is still unsettled and requires detailed time-series analysis. This study consists of a time-series analysis of mudstone- and sandstone-dominated turbidite successions offshore a fan-delta system in the Neogene Aoshima Formation that belongs to the sedimentary fill of the forearc basin of southwest Japan. The formation consists of a monotonous alternation of very fine- to medium-grained sandstones capped by hemipelagic mudstones and, more rarely, by turbidite mudstones. The results show that the autocorrelation function of the time series suggests quasi-periodic variability in the upper sandstone-dominated part, whereas the lower mudstone-dominated part shows a white-noise-like pattern. Rescaled range analysis shows that the number of events per unit time in the lower part is characterized by a random time series, such as Brownian noise with a Hurst exponent of 0.5. In contrast, the thickness of event beds of the lower part and the thickness and the number of events of the upper part are persistent time series with a Hurst exponent > 0.5. These results suggest that the number of turbidite depositional events in the mudstone-dominated part indicates random timing, whereas its thickness time series and the sandstone-dominant part are not governed by simple stochastic processes but are affected by sea-level changes, sediment transport dynamics, and other factors such as, for example, seafloor topography.","PeriodicalId":17044,"journal":{"name":"Journal of Sedimentary Research","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140930541","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jon Lima-Zaloumis, Jack D. Farmer, Elizabeth Trembath-Reichert
Carbonate rocks retain a well preserved record of biologically associated structures at the outcrop to millimeter scale; however, microscale features such as cellular fossils are rarely represented. The lack of microscale textural information in ancient carbonates is commonly attributed to processes relating to carbonate diagenesis. However, there are relatively few examples of precisely how and when these destructive processes occur, particularly in active precipitating systems. To better understand the taphonomy of carbonate precipitating environments through early diagenesis, we investigated Crystal Geyser, an active cold-water carbonate spring (∼ 18°C) located in Grand County, Utah. Here we show that rapid precipitation is effective at initially capturing cell-like structures and forming associated microscale laminated stromatolites; however, these morphologies degrade immediately after their formation. We attribute destructive diagenetic effects to the recrystallization of metastable aragonite into the more stable polymorph calcite (i.e., inversion) and the associated textural coarsening that homogenizes and erases the original fabric (i.e., aggrading neomorphism). Despite the loss of microscale morphological information, chemical biosignatures in the form of macromolecular organics remain dispersed throughout the disrupted carbonate textures. These observations provide an example of penecontemporaneous diagenesis that obliterates primary microscale textures in carbonate rocks. Similar mechanisms and their rapid timing, as shown here, likely contributes to the observed lack of microscale morphological biosignatures in many ancient carbonates. This work further highlights that in such systems, permineralization by a more stable crystalline phase, such as chert, must occur rapidly after deposition to effectively retain these signatures over geological timescales.
{"title":"Rapid diagenesis and microbial biosignature degradation in spring carbonates from Crystal Geyser, Utah, U.S.A.","authors":"Jon Lima-Zaloumis, Jack D. Farmer, Elizabeth Trembath-Reichert","doi":"10.2110/jsr.2023.028","DOIUrl":"https://doi.org/10.2110/jsr.2023.028","url":null,"abstract":"Carbonate rocks retain a well preserved record of biologically associated structures at the outcrop to millimeter scale; however, microscale features such as cellular fossils are rarely represented. The lack of microscale textural information in ancient carbonates is commonly attributed to processes relating to carbonate diagenesis. However, there are relatively few examples of precisely how and when these destructive processes occur, particularly in active precipitating systems. To better understand the taphonomy of carbonate precipitating environments through early diagenesis, we investigated Crystal Geyser, an active cold-water carbonate spring (∼ 18°C) located in Grand County, Utah. Here we show that rapid precipitation is effective at initially capturing cell-like structures and forming associated microscale laminated stromatolites; however, these morphologies degrade immediately after their formation. We attribute destructive diagenetic effects to the recrystallization of metastable aragonite into the more stable polymorph calcite (i.e., inversion) and the associated textural coarsening that homogenizes and erases the original fabric (i.e., aggrading neomorphism). Despite the loss of microscale morphological information, chemical biosignatures in the form of macromolecular organics remain dispersed throughout the disrupted carbonate textures. These observations provide an example of penecontemporaneous diagenesis that obliterates primary microscale textures in carbonate rocks. Similar mechanisms and their rapid timing, as shown here, likely contributes to the observed lack of microscale morphological biosignatures in many ancient carbonates. This work further highlights that in such systems, permineralization by a more stable crystalline phase, such as chert, must occur rapidly after deposition to effectively retain these signatures over geological timescales.","PeriodicalId":17044,"journal":{"name":"Journal of Sedimentary Research","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141551572","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
K. Vasileva, V. Ershova, Mikhail Rogov, Julia Gritsenko, Fedor Maximov, Yaroslav Ovsepyan, Tatiana Okuneva, Anna Rybakova, Daria Kiseleva, O. Vereshchagin
We present a complex study on mineralogical, U/Th dating, isotopic and geochemical characteristics of Pleistocene glendonites (calcite pseupomorphs after ikaite) from the outcrops of Bol’shaya Bakakhnya valley, Eastern Taimyr, Russia. Based on the U/Th dating of the glendonites (37 ± 7 ka) we propose that the glendonites and host sediments were formed during Karginsky interstadial (22—50 ka) – this data corresponds well with published ages of foraminifers and wood fragments from Karginsky deposits of Eastern Taimyr. The main factors leading to ikaite crystallization was presence of organic matter (δ13C varies from -5 to -40‰ V-PDB) in the host clayey sediments and low temperatures (< 7 ºC) of bottom water. Isotopic (δ18O ratios vary from -8 to -33.9‰ V-PDB) and geochemical (PAAS-normalized patterns of rare earth elements) characteristics of the studied glendonites confirm that ikaite crystallization and transformation was influenced by seawater. Carbon was derived from dissolved inorganic carbon, de composed organic matter, and probably methane. Some glendonites are surrounded by concretions (host rock cemented by calcite). The isotopic characteristics of the host concretions and glendonites are similar, so we assume that glendonites and host nodules were formed by the same processes—sulfate reduction coupled with anaerobic decomposition of organic matter. Nevertheless, geochemical characteristics of the host concretions and glendonites differ: Mg/Ca ratio and values of Fe, Mn, Zn, Cd, and U are higher in host concretion than in glendonite. This may reflect differences in crystalline structure of ikaite and high magnesium calcite.
{"title":"Mineralogical composition, isotopic and geochemical characteristics of Pleistocene glendonites from the outcrops of Bol’shaya Balakhnya River, Eastern Taimyr, Russia","authors":"K. Vasileva, V. Ershova, Mikhail Rogov, Julia Gritsenko, Fedor Maximov, Yaroslav Ovsepyan, Tatiana Okuneva, Anna Rybakova, Daria Kiseleva, O. Vereshchagin","doi":"10.2110/jsr.2023.128","DOIUrl":"https://doi.org/10.2110/jsr.2023.128","url":null,"abstract":"We present a complex study on mineralogical, U/Th dating, isotopic and geochemical characteristics of Pleistocene glendonites (calcite pseupomorphs after ikaite) from the outcrops of Bol’shaya Bakakhnya valley, Eastern Taimyr, Russia. Based on the U/Th dating of the glendonites (37 ± 7 ka) we propose that the glendonites and host sediments were formed during Karginsky interstadial (22—50 ka) – this data corresponds well with published ages of foraminifers and wood fragments from Karginsky deposits of Eastern Taimyr. The main factors leading to ikaite crystallization was presence of organic matter (δ13C varies from -5 to -40‰ V-PDB) in the host clayey sediments and low temperatures (< 7 ºC) of bottom water. Isotopic (δ18O ratios vary from -8 to -33.9‰ V-PDB) and geochemical (PAAS-normalized patterns of rare earth elements) characteristics of the studied glendonites confirm that ikaite crystallization and transformation was influenced by seawater. Carbon was derived from dissolved inorganic carbon, de composed organic matter, and probably methane. Some glendonites are surrounded by concretions (host rock cemented by calcite). The isotopic characteristics of the host concretions and glendonites are similar, so we assume that glendonites and host nodules were formed by the same processes—sulfate reduction coupled with anaerobic decomposition of organic matter. Nevertheless, geochemical characteristics of the host concretions and glendonites differ: Mg/Ca ratio and values of Fe, Mn, Zn, Cd, and U are higher in host concretion than in glendonite. This may reflect differences in crystalline structure of ikaite and high magnesium calcite.","PeriodicalId":17044,"journal":{"name":"Journal of Sedimentary Research","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141359017","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sediment waves are common in confined to unconfined settings on modern marine slopes and basin floors worldwide. Their morphology and stratal patterns show that many of them migrate upslope and upflow, a characteristic thought to record Froude-supercritical flow conditions associated with sediment gravity flows and density cascades. Few sediment waves of this type have been observed in the ancient rock record. This study reports the discovery of a giant (over 20,000 km2) sediment-wave field in Lower Mississippian carbonates and shales of the Fort Payne Formation in Tennessee and Kentucky. Sediment waves are present in the clinothem slopes and basin floor of a distally steepened ramp as seismic-scale bedforms ranging from 100 to 700 m long and 15-50 m high. Dominant facies include crinoidal shales, packstones, and rudstones. Many of the beds are sharp-based and graded, indicating sediment-gravity-flow deposition. Upslope-inclined rudstones (backsets) and wavy beds with upflow and downflow laminae are common and indicate supercritical flow conditions. These observations and interpretations are in stark contrast to previous interpretations of crinoidal bioherms and Waulsortian-type mounds. Basin physiography, a cool-water heterozoan carbonate factory and coastal upwelling were key factors in establishing a rapidly prograding ramp characterized by high rates of sediment production and basinward shedding. Sediment gravity flows and density cascades transported crinoidal grains downslope and entrained crinoids that inhabited the slope. Flows frequently reached Fr-supercritical flow conditions that led to the formation of sediment waves similar to those in modern marine slopes. This sediment-wave field is one of the first to be documented in the ancient rock record, and its extent is enormous. The near absence of other reported ancient examples must be due to misinterpretation (mounds, slumps) and the problem of observational scale and resolution. Sediment waves are often larger than outcrops. Lack of recognition of sediment waves in subsurface seismic sections is probably due to misinterpretation and the insufficient resolution. Perhaps this study demonstrates the need for revisiting and updating existing facies models of carbonate-sediment transport and depositional processes across slopes and basin floors.
{"title":"Giant Sediment-Wave Field and Supercritical Flows in a Distally Steepened Ramp, Fort Payne Formation (Lower Mississippian), Kentucky-Tennessee, U.S.A.","authors":"Handford C. Robertson","doi":"10.2110/jsr.2024.032","DOIUrl":"https://doi.org/10.2110/jsr.2024.032","url":null,"abstract":"Sediment waves are common in confined to unconfined settings on modern marine slopes and basin floors worldwide. Their morphology and stratal patterns show that many of them migrate upslope and upflow, a characteristic thought to record Froude-supercritical flow conditions associated with sediment gravity flows and density cascades. Few sediment waves of this type have been observed in the ancient rock record. This study reports the discovery of a giant (over 20,000 km2) sediment-wave field in Lower Mississippian carbonates and shales of the Fort Payne Formation in Tennessee and Kentucky. Sediment waves are present in the clinothem slopes and basin floor of a distally steepened ramp as seismic-scale bedforms ranging from 100 to 700 m long and 15-50 m high. Dominant facies include crinoidal shales, packstones, and rudstones. Many of the beds are sharp-based and graded, indicating sediment-gravity-flow deposition. Upslope-inclined rudstones (backsets) and wavy beds with upflow and downflow laminae are common and indicate supercritical flow conditions. These observations and interpretations are in stark contrast to previous interpretations of crinoidal bioherms and Waulsortian-type mounds. Basin physiography, a cool-water heterozoan carbonate factory and coastal upwelling were key factors in establishing a rapidly prograding ramp characterized by high rates of sediment production and basinward shedding. Sediment gravity flows and density cascades transported crinoidal grains downslope and entrained crinoids that inhabited the slope. Flows frequently reached Fr-supercritical flow conditions that led to the formation of sediment waves similar to those in modern marine slopes. This sediment-wave field is one of the first to be documented in the ancient rock record, and its extent is enormous. The near absence of other reported ancient examples must be due to misinterpretation (mounds, slumps) and the problem of observational scale and resolution. Sediment waves are often larger than outcrops. Lack of recognition of sediment waves in subsurface seismic sections is probably due to misinterpretation and the insufficient resolution. Perhaps this study demonstrates the need for revisiting and updating existing facies models of carbonate-sediment transport and depositional processes across slopes and basin floors.","PeriodicalId":17044,"journal":{"name":"Journal of Sedimentary Research","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141267115","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Braided rivers distribute sediment across landscapes, often forming wide channel belts that are preserved in stratigraphy as coarse-grained deposits. Theoretical work has established quantitative links between the depth distribution of formative channels in a braided river and the geometry of their preserved strata. However, testing these predictive relationships between geomorphic process and stratigraphic product requires examining how braided rivers and their deposits coevolve, with high resolution in both space and time. Here, using a series of four runs of a physical experiment, we examine the controls of water discharge and slope on the resulting geometry of preserved deposits. Specifically, we focus on how a twofold variation in water discharge and initial riverbed slope affects the spatiotemporal distribution of channel depths and the geometry of preserved deposits of a braided river. We find that the channel depths in the laboratory experiment are described by a two-parameter gamma distributio n and the deepest scours correspond to zones of erosion at channel-belt margins and channel-thread confluences within the channel belt. We use a reduced complexity flow model to reconstruct flow depths, which were shallower compared to channel thalweg depths. Synthetic stratigraphy built from timeseries of topographic surfaces shows that the distribution of cut-and-fill unit thickness is invariant across the experiments and is determined by the variability in scour depths. We show that the distribution of cut-and-fill unit thickness can be used to reconstruct formative channel-depth distributions and that the mean thickness of these units is 0.31 to 0.62 times the mean formative flow depth across all experiments. Our results suggest that variations in discharge and slope do not translate to measurable differences in preserved cut-and-fill unit thickness, suggesting that changes in external forcings are only likely to be preserved in braided river deposits when they exceed a certain threshold of change.
{"title":"Scour depth variability controls channel-scale stratigraphy in experimental braided rivers","authors":"Feifei Zhao, V. Ganti, Ajay B. Limaye","doi":"10.2110/jsr.2023.118","DOIUrl":"https://doi.org/10.2110/jsr.2023.118","url":null,"abstract":"Braided rivers distribute sediment across landscapes, often forming wide channel belts that are preserved in stratigraphy as coarse-grained deposits. Theoretical work has established quantitative links between the depth distribution of formative channels in a braided river and the geometry of their preserved strata. However, testing these predictive relationships between geomorphic process and stratigraphic product requires examining how braided rivers and their deposits coevolve, with high resolution in both space and time. Here, using a series of four runs of a physical experiment, we examine the controls of water discharge and slope on the resulting geometry of preserved deposits. Specifically, we focus on how a twofold variation in water discharge and initial riverbed slope affects the spatiotemporal distribution of channel depths and the geometry of preserved deposits of a braided river. We find that the channel depths in the laboratory experiment are described by a two-parameter gamma distributio n and the deepest scours correspond to zones of erosion at channel-belt margins and channel-thread confluences within the channel belt. We use a reduced complexity flow model to reconstruct flow depths, which were shallower compared to channel thalweg depths. Synthetic stratigraphy built from timeseries of topographic surfaces shows that the distribution of cut-and-fill unit thickness is invariant across the experiments and is determined by the variability in scour depths. We show that the distribution of cut-and-fill unit thickness can be used to reconstruct formative channel-depth distributions and that the mean thickness of these units is 0.31 to 0.62 times the mean formative flow depth across all experiments. Our results suggest that variations in discharge and slope do not translate to measurable differences in preserved cut-and-fill unit thickness, suggesting that changes in external forcings are only likely to be preserved in braided river deposits when they exceed a certain threshold of change.","PeriodicalId":17044,"journal":{"name":"Journal of Sedimentary Research","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140716561","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xavier Coll, D. Gómez‐Gras, M. Roigé, Daniel Stockli, A. Teixell, S. Boya
The Eocene to Miocene clastic wedge of the south Pyrenean basin constitutes a reference model to understand the progressive evolution of sediment provenance and source-to-sink dynamics in a foreland basin. We present new detrital zircon (DZ) U-Pb and U-Pb-He (ZHe) double dating data from the Jaca basin and the Ebro basin, providing insights into the evolution of the sedimentary systems that record a major tectonic and drainage reorganization from the late Eocene to Miocene. Three distinct DZ U-Pb signatures have been identified: (i) Variscan dominated; (ii) mixed Cadomian-Variscan; (iii) Cadomian dominated; and two DZ ZHe signatures (i) Pyrenean dominated; (ii) pre-Pyrenean dominated. Coupling DZ U-Pb, ZHe, and petrographic data allows us to discriminate among distinct Pyrenean sources as well as to understand how DZ signatures are propagated in a source-to-sink system. Our results indicate that while the eastern Jaca basin was fed from eastern source areas located in the central and eastern Pyrenees, the western Jaca basin was fed from the Basque massifs and the Urbasa-Andía Sierra (Basque-Cantabrian Pyrenees).
{"title":"Detrital Zircon U-Pb and (U-Th)/He double dating provenance signatures in the Jaca foreland basin: Interplay of direct vs recycled sources during Pyrenean orogenic growth","authors":"Xavier Coll, D. Gómez‐Gras, M. Roigé, Daniel Stockli, A. Teixell, S. Boya","doi":"10.2110/jsr.2023.066","DOIUrl":"https://doi.org/10.2110/jsr.2023.066","url":null,"abstract":"The Eocene to Miocene clastic wedge of the south Pyrenean basin constitutes a reference model to understand the progressive evolution of sediment provenance and source-to-sink dynamics in a foreland basin. We present new detrital zircon (DZ) U-Pb and U-Pb-He (ZHe) double dating data from the Jaca basin and the Ebro basin, providing insights into the evolution of the sedimentary systems that record a major tectonic and drainage reorganization from the late Eocene to Miocene. Three distinct DZ U-Pb signatures have been identified: (i) Variscan dominated; (ii) mixed Cadomian-Variscan; (iii) Cadomian dominated; and two DZ ZHe signatures (i) Pyrenean dominated; (ii) pre-Pyrenean dominated. Coupling DZ U-Pb, ZHe, and petrographic data allows us to discriminate among distinct Pyrenean sources as well as to understand how DZ signatures are propagated in a source-to-sink system. Our results indicate that while the eastern Jaca basin was fed from eastern source areas located in the central and eastern Pyrenees, the western Jaca basin was fed from the Basque massifs and the Urbasa-Andía Sierra (Basque-Cantabrian Pyrenees).","PeriodicalId":17044,"journal":{"name":"Journal of Sedimentary Research","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140723959","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jack Stacey, H. Corlett, Cathy Hollis, David Hills
Differentially dolomitized carbonate strata in the Western Canada Sedimentary Basin (WCSB) are increasingly targeted for carbon capture, utilization and storage (CCUS), yet few studies have evaluated the petrophysical characteristics of these conventional hydrocarbon reservoirs for this purpose. To address this, this study uses drill core analysis (sedimentology, diagenesis, pore morphology and distribution), together with core plug and production data, to evaluate the properties of five depleted oil and gas fields in the Middle to Upper Devonian Swan Hills Formation, Leduc Formation and Wabamun Group. The Swan Hills and Leduc Formations are comprised of reef, shoal and lagoon deposits that are predominantly fossil-rich (e.g. stromatoporoid-dominated rudstones and boundstones). In contrast, the carbonate ramp deposits of the Wabamun Group are fossil-poor, consisting instead of variably bioturbated carbonate mudstones, wackestones and packstones. Replacement dolomitization is variable throughout each stratigraphic unit, but generally occurs within fossil-rich and/or heavily bioturbated intervals. Fracture densities are broadly comparable in limestone and dolostone. Porosity in the Swan Hills and Leduc Formations is predominantly moldic and vuggy, occurring where fossils (e.g. stromatoporoids) are partially or fully dissolved. Pore space in the Wabamun Group is mostly restricted to intercrystalline porosity within burrows. In general, burial cements (e.g. calcite and dolomite) are volumetrically insignificant and only partially fill pores. Exceptions to this include porosity-occluding cements associated w ith fractures and breccias in the vicinity of faults. Dolomitization and depositional facies are found to exert a strong control on pore morphology, distribution and interconnectivity. Porosity is primarily controlled by the relative abundance of skeletal grains and by the presence of burrows. These highly porous facies acted as fluid pathways during burial diagenesis, resulting in their preferential dolomitization, solution enhancement of pre-existing pores, and creation of volume reduction-related porosity. The high CO2 storage capacity and low unplanned plume migration risk (due to depositional/diagenetic baffles) of dolomitized reefal reservoirs (e.g. Swan Hills and Leduc Formations) make them more attractive targets for CCUS than those with limited capacity and/or potential migration pathways (e.g. fault-related fractures and breccias in the Wabamun Group). These results demonstrate that drill core analysis, in combination with legacy data, can provide valuable insights into the factors that control reservoir CO2 injectivity, plume migration and storage capacity.
{"title":"Reservoir evaluation of dolomitized Devonian strata in the Western Canada Sedimentary Basin: Implications for carbon capture, utilization and storage","authors":"Jack Stacey, H. Corlett, Cathy Hollis, David Hills","doi":"10.2110/jsr.2023.082","DOIUrl":"https://doi.org/10.2110/jsr.2023.082","url":null,"abstract":"Differentially dolomitized carbonate strata in the Western Canada Sedimentary Basin (WCSB) are increasingly targeted for carbon capture, utilization and storage (CCUS), yet few studies have evaluated the petrophysical characteristics of these conventional hydrocarbon reservoirs for this purpose. To address this, this study uses drill core analysis (sedimentology, diagenesis, pore morphology and distribution), together with core plug and production data, to evaluate the properties of five depleted oil and gas fields in the Middle to Upper Devonian Swan Hills Formation, Leduc Formation and Wabamun Group. The Swan Hills and Leduc Formations are comprised of reef, shoal and lagoon deposits that are predominantly fossil-rich (e.g. stromatoporoid-dominated rudstones and boundstones). In contrast, the carbonate ramp deposits of the Wabamun Group are fossil-poor, consisting instead of variably bioturbated carbonate mudstones, wackestones and packstones. Replacement dolomitization is variable throughout each stratigraphic unit, but generally occurs within fossil-rich and/or heavily bioturbated intervals. Fracture densities are broadly comparable in limestone and dolostone. Porosity in the Swan Hills and Leduc Formations is predominantly moldic and vuggy, occurring where fossils (e.g. stromatoporoids) are partially or fully dissolved. Pore space in the Wabamun Group is mostly restricted to intercrystalline porosity within burrows. In general, burial cements (e.g. calcite and dolomite) are volumetrically insignificant and only partially fill pores. Exceptions to this include porosity-occluding cements associated w ith fractures and breccias in the vicinity of faults. Dolomitization and depositional facies are found to exert a strong control on pore morphology, distribution and interconnectivity. Porosity is primarily controlled by the relative abundance of skeletal grains and by the presence of burrows. These highly porous facies acted as fluid pathways during burial diagenesis, resulting in their preferential dolomitization, solution enhancement of pre-existing pores, and creation of volume reduction-related porosity. The high CO2 storage capacity and low unplanned plume migration risk (due to depositional/diagenetic baffles) of dolomitized reefal reservoirs (e.g. Swan Hills and Leduc Formations) make them more attractive targets for CCUS than those with limited capacity and/or potential migration pathways (e.g. fault-related fractures and breccias in the Wabamun Group). These results demonstrate that drill core analysis, in combination with legacy data, can provide valuable insights into the factors that control reservoir CO2 injectivity, plume migration and storage capacity.","PeriodicalId":17044,"journal":{"name":"Journal of Sedimentary Research","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140729746","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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