An anhydrite caprock overlies 65% of the 329 onshore salt stocks of the U.S. Gulf Coastal Region, South-Central U.S. The caprock consists of a succession of katatectic (downward-building) layers of anhydrite (each typically 1 to 4 cm thick) and an upper, black pyrite lamina (approx. 0.1 mm thick). The older (upper) katatectic layers are usually highly deformed. During four stages, these fundamental layers formed at the crest of shallow (less than 1,200 m) salt stocks. Repetition of sets of the stages resulted in the cyclicity. The closed stage: A flush, nearly planar contact separated mature anhydrite caprock from an underlying salt-stock crest. As the diapir elevated by a few mm/yr, it arched the caprock; it also opened conduits at the stock’s uppermost anhydrite sheath, allowing NaCl-undersaturated water from outside the diapir to contact the salt stock. The open-dynamic stage: Along the perimeter of the uppermost salt stock, a narrow, annular halite cave advanced inward and upward directly below the slightly convex base of the anhydrite caprock. The most NaCl-aggressive water rose by free convection to the highest elevations and dissolved halite. The dense, solute-enhanced water then reversed direction and, again, by free convection, flowed past the stock’s margin into country rock; NaCl-undersaturated water replaced the departing brine. A water-filled, commonly ring-shaped, planar cave up to several meters high expanded over the stock’s crest. Sparse physical supports, buoyancy, arched caprock, and high artesian water pressure prevented the cave’s collapse. The cave’s halite floor dissolved vertically downward faster than it moved diapirically upward. As the crestal halite dissolved, a small amount of residual pyrite and, typically, a layer up to approx. 10 cm thick of residual anhydrite (generally 3-8 wt % of the stocks) accumulated on the cave floor. The open-static stage: The persistent “attack” of halite highs by the NaCl-undersaturated water eventually caused the slope of the cave’s floor to approach horizontality. The density-driven flow slowed markedly, and a static cover of NaCl-saturated brine thwarted the dissolution of the halite floor. The downward movement of the cave’s floor reversed, and it moved slowly upward via diapirism. Concurrently, an anhydrite sheath evolved around the uppermost stock. The accretionary stage: The cave closed within a few thousand years, and active diapirism underplated the admixed residual minerals onto the base of the caprock. The uppermost, now compact, residual anhydrite dissolved within the high-pressure environment, leaving the discrete, topmost, thin, black pyrite lamina. With the accretion of the residual minerals, a katatectic layer formed at the base of a succession of such layers. The closed stage recurred, and a new katatectic cycle began forming. Variations of the four genetic stages probably occurred during the formation of anhydrite caprocks in other worldwide salt dome provinces, but beca
{"title":"Cyclicity of Katatectic Layers within Anhydrite Caprocks, U.S. Gulf Coastal Region","authors":"Douglas W. Kirkland","doi":"10.2110/jsr.2023.119","DOIUrl":"https://doi.org/10.2110/jsr.2023.119","url":null,"abstract":"An anhydrite caprock overlies 65% of the 329 onshore salt stocks of the U.S. Gulf Coastal Region, South-Central U.S. The caprock consists of a succession of katatectic (downward-building) layers of anhydrite (each typically 1 to 4 cm thick) and an upper, black pyrite lamina (approx. 0.1 mm thick). The older (upper) katatectic layers are usually highly deformed. During four stages, these fundamental layers formed at the crest of shallow (less than 1,200 m) salt stocks. Repetition of sets of the stages resulted in the cyclicity. The closed stage: A flush, nearly planar contact separated mature anhydrite caprock from an underlying salt-stock crest. As the diapir elevated by a few mm/yr, it arched the caprock; it also opened conduits at the stock’s uppermost anhydrite sheath, allowing NaCl-undersaturated water from outside the diapir to contact the salt stock. The open-dynamic stage: Along the perimeter of the uppermost salt stock, a narrow, annular halite cave advanced inward and upward directly below the slightly convex base of the anhydrite caprock. The most NaCl-aggressive water rose by free convection to the highest elevations and dissolved halite. The dense, solute-enhanced water then reversed direction and, again, by free convection, flowed past the stock’s margin into country rock; NaCl-undersaturated water replaced the departing brine. A water-filled, commonly ring-shaped, planar cave up to several meters high expanded over the stock’s crest. Sparse physical supports, buoyancy, arched caprock, and high artesian water pressure prevented the cave’s collapse. The cave’s halite floor dissolved vertically downward faster than it moved diapirically upward. As the crestal halite dissolved, a small amount of residual pyrite and, typically, a layer up to approx. 10 cm thick of residual anhydrite (generally 3-8 wt % of the stocks) accumulated on the cave floor. The open-static stage: The persistent “attack” of halite highs by the NaCl-undersaturated water eventually caused the slope of the cave’s floor to approach horizontality. The density-driven flow slowed markedly, and a static cover of NaCl-saturated brine thwarted the dissolution of the halite floor. The downward movement of the cave’s floor reversed, and it moved slowly upward via diapirism. Concurrently, an anhydrite sheath evolved around the uppermost stock. The accretionary stage: The cave closed within a few thousand years, and active diapirism underplated the admixed residual minerals onto the base of the caprock. The uppermost, now compact, residual anhydrite dissolved within the high-pressure environment, leaving the discrete, topmost, thin, black pyrite lamina. With the accretion of the residual minerals, a katatectic layer formed at the base of a succession of such layers. The closed stage recurred, and a new katatectic cycle began forming. Variations of the four genetic stages probably occurred during the formation of anhydrite caprocks in other worldwide salt dome provinces, but beca","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":"140731557","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}
Sonia Perrotta, Mirko Barone, Kathleen M. Marsaglia, Kitty L. Milliken, Vincenzo Perrone, Salvatore Critelli
Serpentine-bearing sediment, a rare sediment type that is formed and deposited in divergent, convergent, transform, and collisional plate-tectonic settings, carries important evidence of sediment provenance. Specific sources of serpentine-rich sediment display grain assemblages of distinct character that can be used to infer the serpentinization condition and sediment formation. This study reports quantitative and qualitative results on serpentine components in sandstones from Ocean Drilling Program Legs 149 (Iberia), 210 (Newfoundland), and 125 (Mariana and Izu–Bonin regions), and from serpentine-rich debris flows and arenitic breccias in deep-water successions in the Northern Apennine fold–thrust belt. We propose a textural scheme that offers a visual guidance for evaluating serpentinite grains that can be broadly adopted, is easily reproducible, and reduces user bias in determining compositional modes that allow comparison of serpentinite grain populations in arenites from different depositional environments, provenance, and associated tectonic settings. These data allow us to define a scheme for serpentine-dominated deposits that demonstrates the presence of two main groups of grain textures (pseudomorphic and non-pesudomorphic) with specific mineralogy and crystal shape as a function of temperature and pressure in the source rocks.The quantitative analysis of the serpentine-rich arenites and fine-grained sediments derived from forearc and rifted continental-margin settings shows that the studied samples are characterized by high percentages (c. ≥ 80%) of serpentine detritus and subordinate dense minerals and other lithic fragments, including basalt. In rifted continental-margin settings, the prevalent textures in serpentinite sandstones consist of polygonal mesh, mesh-core, and hourglass that all belong to the pseudomorphic category, which preserves the pre-serpentine features and mineralogy. These textures are typically formed in low-temperature conditions (< 390°C); lizardite is the most common mineral, along with minor chrysotile and, in rare cases, antigorite. In contrast, in forearc settings, serpentine-rich grain assemblages exhibit dominantly non-pseudomorphic, interlocking, and interpenetrating textures, dominantly composed of lizardite and recrystallization of lizardite by antigorite. Minor preserved ultramafic minerals related to dynamic recrystallization might be associated with the diapiric rise and protrusion of serpentine bodies.The Northern Apennines case study adopted to test this model indicates that the relationship of detrital serpentine texture to setting can be employed in provenance studies. Firstly, serpentine-bearing sediments derived from ophiolites deformed in fold–thrust belts have more variable serpentinite content, ranging from a few percent to < 10% for samples from deep marine environments, to typically c. 20 to ≤ 50% for stream and beach samples. This compositional variation arises from mixing of sediments der
{"title":"Detrital signatures of clastic serpentinite in tectonically diverse settings and interpretation of an example from the Northern Apennines","authors":"Sonia Perrotta, Mirko Barone, Kathleen M. Marsaglia, Kitty L. Milliken, Vincenzo Perrone, Salvatore Critelli","doi":"10.2110/jsr.2022.093","DOIUrl":"https://doi.org/10.2110/jsr.2022.093","url":null,"abstract":"Serpentine-bearing sediment, a rare sediment type that is formed and deposited in divergent, convergent, transform, and collisional plate-tectonic settings, carries important evidence of sediment provenance. Specific sources of serpentine-rich sediment display grain assemblages of distinct character that can be used to infer the serpentinization condition and sediment formation. This study reports quantitative and qualitative results on serpentine components in sandstones from Ocean Drilling Program Legs 149 (Iberia), 210 (Newfoundland), and 125 (Mariana and Izu–Bonin regions), and from serpentine-rich debris flows and arenitic breccias in deep-water successions in the Northern Apennine fold–thrust belt. We propose a textural scheme that offers a visual guidance for evaluating serpentinite grains that can be broadly adopted, is easily reproducible, and reduces user bias in determining compositional modes that allow comparison of serpentinite grain populations in arenites from different depositional environments, provenance, and associated tectonic settings. These data allow us to define a scheme for serpentine-dominated deposits that demonstrates the presence of two main groups of grain textures (pseudomorphic and non-pesudomorphic) with specific mineralogy and crystal shape as a function of temperature and pressure in the source rocks.The quantitative analysis of the serpentine-rich arenites and fine-grained sediments derived from forearc and rifted continental-margin settings shows that the studied samples are characterized by high percentages (c. ≥ 80%) of serpentine detritus and subordinate dense minerals and other lithic fragments, including basalt. In rifted continental-margin settings, the prevalent textures in serpentinite sandstones consist of polygonal mesh, mesh-core, and hourglass that all belong to the pseudomorphic category, which preserves the pre-serpentine features and mineralogy. These textures are typically formed in low-temperature conditions (< 390°C); lizardite is the most common mineral, along with minor chrysotile and, in rare cases, antigorite. In contrast, in forearc settings, serpentine-rich grain assemblages exhibit dominantly non-pseudomorphic, interlocking, and interpenetrating textures, dominantly composed of lizardite and recrystallization of lizardite by antigorite. Minor preserved ultramafic minerals related to dynamic recrystallization might be associated with the diapiric rise and protrusion of serpentine bodies.The Northern Apennines case study adopted to test this model indicates that the relationship of detrital serpentine texture to setting can be employed in provenance studies. Firstly, serpentine-bearing sediments derived from ophiolites deformed in fold–thrust belts have more variable serpentinite content, ranging from a few percent to < 10% for samples from deep marine environments, to typically c. 20 to ≤ 50% for stream and beach samples. This compositional variation arises from mixing of sediments der","PeriodicalId":17044,"journal":{"name":"Journal of Sedimentary Research","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140323253","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 present study provides insights into the origin of siderite cementation in closely interbedded bipartite mudstone to sandstone Pennsylvanian strata from the Anadarko Basin. Mineralogical, geochemical, and stable-isotope data were collected from 80 siderite samples and their immediate non-siderite-bearing regions. Geometrically, siderite mineralization occurs in the form of concretions or bands, with the latter being the most common textural type and occurring solely in mudstone, whereas the former is found in both sandstone and mudstone. This microtextural and geochemical investigation posits siderite as a derivate of biological processes at the sediment–water interface. Bacteria cell walls denoted by an omnipresent nanoglobule structure dominate the areas of mineralization. Mineral quantifications indicate higher phyllosilicate content within the mineralization compared to the non-mineralized sediment reflecting the role the clay minerals provide as a source of bio-essential cations, labile FeOx, and organic matter needed for microbial colonies to flourish. Following the formation of biological siderite, the energetically favorable mineralization surfaces served as nuclei for further precipitation of mesogenetic inorganic siderite enriched in 16O. The second mesogenetic cementation features rhombohedral siderite overgrowths with increasing Mg-concentration on the outer rims of nanoglobules. The identified bands and concretions were formed during periods of relative sea-level highs, whereas the siderite-cemented intraclasts were eroded and deposited downstream during times of relative sea-level lows. This is corroborated by relatively low (Ca-Mg)/Fe substitution in eogenetic siderite, typical of mineralization in meteoric-water-dominated realms. Finally, based on enrichment in 12C and textural observations, which suggest suboxic geochemical conditions, we conclude that the ability of siderite to form early on allowed it to maintain net rock porosity by encasing quartz and inhibiting its overgrowth process.
{"title":"Understanding siderite mineralization in phyllosilicate-associated cementations in the mid-Carboniferous Anadarko Basin clastic series, U.S.A.","authors":"Owen F. Smith, Branimir ŠegviĆ, Dustin E. Sweet","doi":"10.2110/jsr.2023.100","DOIUrl":"https://doi.org/10.2110/jsr.2023.100","url":null,"abstract":"The present study provides insights into the origin of siderite cementation in closely interbedded bipartite mudstone to sandstone Pennsylvanian strata from the Anadarko Basin. Mineralogical, geochemical, and stable-isotope data were collected from 80 siderite samples and their immediate non-siderite-bearing regions. Geometrically, siderite mineralization occurs in the form of concretions or bands, with the latter being the most common textural type and occurring solely in mudstone, whereas the former is found in both sandstone and mudstone. This microtextural and geochemical investigation posits siderite as a derivate of biological processes at the sediment–water interface. Bacteria cell walls denoted by an omnipresent nanoglobule structure dominate the areas of mineralization. Mineral quantifications indicate higher phyllosilicate content within the mineralization compared to the non-mineralized sediment reflecting the role the clay minerals provide as a source of bio-essential cations, labile FeOx, and organic matter needed for microbial colonies to flourish. Following the formation of biological siderite, the energetically favorable mineralization surfaces served as nuclei for further precipitation of mesogenetic inorganic siderite enriched in 16O. The second mesogenetic cementation features rhombohedral siderite overgrowths with increasing Mg-concentration on the outer rims of nanoglobules. The identified bands and concretions were formed during periods of relative sea-level highs, whereas the siderite-cemented intraclasts were eroded and deposited downstream during times of relative sea-level lows. This is corroborated by relatively low (Ca-Mg)/Fe substitution in eogenetic siderite, typical of mineralization in meteoric-water-dominated realms. Finally, based on enrichment in 12C and textural observations, which suggest suboxic geochemical conditions, we conclude that the ability of siderite to form early on allowed it to maintain net rock porosity by encasing quartz and inhibiting its overgrowth process.","PeriodicalId":17044,"journal":{"name":"Journal of Sedimentary Research","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140586796","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}
Katherine L. Maier, S. Nodder, Stacy Deppeler, Peter Gerring, Grace Frontin-Rollet, Rachel Hale, Oliver Twigge, Sarah J. Bury
Submarine canyons are important deep-sea environments and conduits for transferring and accumulating sediment and organic matter and pollutants. Recent advances in observing, sampling, and analysing modern canyon sediment transport systems illustrate near-seafloor dynamics and highlight the potential roles of submarine canyons in transporting and storing organic carbon, nutrients, and contaminants in the deep sea, with implications for deep-sea ecosystems and global carbon budgets. Kaikōura Canyon, offshore northeastern Te Waipounamu South Island, Aotearoa New Zealand, is a benthic biomass hotspot that experienced an earthquake-triggered, canyon-flushing event in 2016. On return to the canyon in October 2020, benthic landers, with sediment traps at 2 m above the seafloor, were deployed along the canyon axis in approx. 900–1500 m water depths for a period of three weeks. These instrumented platforms provide a detailed view of near-seafloor sediment and organic carbon transport between canyon-flushing e vents, showing that the canyon environment hosts dynamic physical processes and short-term sediment fluxes and transport. Variations in sediment and organic carbon flux down-canyon and over time include small-scale sediment transport events, some of which are interpreted as turbidity currents, occurring on much shorter timescales than earthquake recurrence. We compare Kaikōura Canyon results with other longshore-fed, shelf-incised global submarine canyons and deep-ocean sites, revealing differences and likely multiple controlling factors for near-seafloor sediment flux. This Kaikōura Canyon high-resolution, benthic lander timeseries dataset highlights the complexity of submarine canyons and their role in organic carbon flux to the deep ocean, even under high present-day sea-level conditions. Evolving insights underscore the need for more observational data and samples to further quantify submarine canyon sediment and organic carbon transport and contribute to global evaluations of deep-sea canyon distribu tary systems.
{"title":"Dynamic near-seafloor sediment transport in Kaikōura Canyon following a large canyon-flushing event","authors":"Katherine L. Maier, S. Nodder, Stacy Deppeler, Peter Gerring, Grace Frontin-Rollet, Rachel Hale, Oliver Twigge, Sarah J. Bury","doi":"10.2110/jsr.2023.117","DOIUrl":"https://doi.org/10.2110/jsr.2023.117","url":null,"abstract":"Submarine canyons are important deep-sea environments and conduits for transferring and accumulating sediment and organic matter and pollutants. Recent advances in observing, sampling, and analysing modern canyon sediment transport systems illustrate near-seafloor dynamics and highlight the potential roles of submarine canyons in transporting and storing organic carbon, nutrients, and contaminants in the deep sea, with implications for deep-sea ecosystems and global carbon budgets. Kaikōura Canyon, offshore northeastern Te Waipounamu South Island, Aotearoa New Zealand, is a benthic biomass hotspot that experienced an earthquake-triggered, canyon-flushing event in 2016. On return to the canyon in October 2020, benthic landers, with sediment traps at 2 m above the seafloor, were deployed along the canyon axis in approx. 900–1500 m water depths for a period of three weeks. These instrumented platforms provide a detailed view of near-seafloor sediment and organic carbon transport between canyon-flushing e vents, showing that the canyon environment hosts dynamic physical processes and short-term sediment fluxes and transport. Variations in sediment and organic carbon flux down-canyon and over time include small-scale sediment transport events, some of which are interpreted as turbidity currents, occurring on much shorter timescales than earthquake recurrence. We compare Kaikōura Canyon results with other longshore-fed, shelf-incised global submarine canyons and deep-ocean sites, revealing differences and likely multiple controlling factors for near-seafloor sediment flux. This Kaikōura Canyon high-resolution, benthic lander timeseries dataset highlights the complexity of submarine canyons and their role in organic carbon flux to the deep ocean, even under high present-day sea-level conditions. Evolving insights underscore the need for more observational data and samples to further quantify submarine canyon sediment and organic carbon transport and contribute to global evaluations of deep-sea canyon distribu tary systems.","PeriodicalId":17044,"journal":{"name":"Journal of Sedimentary Research","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140259745","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}
Austin J. McGlannan, Alicia Bonar, Lily Pfeifer, Sebastian Steinig, Paul Valdes, Steven Adams, David Duarte, Benmadi Milad, Andrew Cullen, Gerilyn S. Soreghan
We thank Wilson and Schieber for their discussion, as our paper in Current Ripples presented a new hypothesis, and we welcome tests of that hypothesis. Current Ripples encourages “provocative papers on sedimentary geology” so we are happy to motivate future research toward advancing knowledge on the Devono-Mississippian of North America.Through an integration of paleogeography, paleoclimate, grain size, detrital-zircon provenance, geochemistry, and surface-wind models, McGlannan et al. (2022) proposed that eolian transport supplied significant siliciclastic material to Devono-Mississippian marine strata of the North American midcontinent. Wilson and Schieber (2024) begin their discussion with the statement that “…extrapolating the inferred sedimentary dynamics of one stratigraphic interval (Early Mississippian) across a sequence boundary to rocks that were deposited multiple millions of years earlier (Late Devonian) is neither recommended nor considered good practice.” We find this odd, akin to arguing that, e.g., sediment dynamics of glacioeustasy in the Pleistocene cannot apply to glacioeustasy that operated in the Pennsylvanian. Processes can apply across time, as long as the tenets of uniformity of process (uniformitarianism) are followed. Wilson and Schieber (2024) then focus on three main arguments to challenge the validity of our hypothesis for the Late Devonian in particular.Regarding the issue of an authigenic or detrital origin for the silica, we recognize that Schieber and his collaborators have extensive experience with mudstone petrography and petrology, are aware of and respect their work documenting diagenetic silica in mudstones, and indeed acknowledge in our paper the pervasive presence of diagenetic and biogenic silica in the Woodford Shale. For example, Figure 5B in McGlannan et al. (2022) illustrates the rhythmic, thin, chert-like beds in the Woodford Shale. Wilson and Schieber note that they have studied samples from the same sites we studied and found diagenetic silica. We do not doubt this. Owing to the common presence of diagenetic silica, we preferentially avoided silica-rich facies and predominantly sampled laminated shale facies. Wilson and Schieber (2024) suggest that we generated sand- and silt-size particles “upon crushing–processing” but, as we detailed in our paper, “Samples were gently crushed with a ceramic mortar and pestle to pea-size gravel to accelerate chemical reactions, then rinsed with distilled water and sieved at 250 μm to remove any fines generated during crushing” that might be erroneously incorporated in the grain-size analyses. Of 19 Woodford Shale samples, 12 were selected for particle-size measurement after smear-slide analysis to verify disaggregation and presence of a preponderance of detrital material (Supplemental File 3 and Fig. 6A in McGlannan et al. 2022), which included not only quartz, but minor feldspar and even (rare) accessory minerals such as zircon. We acknowledge that, despite our e
{"title":"An eolian dust origin for clastic fines of Devono-Mississippian mudrocks of the greater North American midcontinent—Reply","authors":"Austin J. McGlannan, Alicia Bonar, Lily Pfeifer, Sebastian Steinig, Paul Valdes, Steven Adams, David Duarte, Benmadi Milad, Andrew Cullen, Gerilyn S. Soreghan","doi":"10.2110/jsr.2023.122","DOIUrl":"https://doi.org/10.2110/jsr.2023.122","url":null,"abstract":"We thank Wilson and Schieber for their discussion, as our paper in Current Ripples presented a new hypothesis, and we welcome tests of that hypothesis. Current Ripples encourages “provocative papers on sedimentary geology” so we are happy to motivate future research toward advancing knowledge on the Devono-Mississippian of North America.Through an integration of paleogeography, paleoclimate, grain size, detrital-zircon provenance, geochemistry, and surface-wind models, McGlannan et al. (2022) proposed that eolian transport supplied significant siliciclastic material to Devono-Mississippian marine strata of the North American midcontinent. Wilson and Schieber (2024) begin their discussion with the statement that “…extrapolating the inferred sedimentary dynamics of one stratigraphic interval (Early Mississippian) across a sequence boundary to rocks that were deposited multiple millions of years earlier (Late Devonian) is neither recommended nor considered good practice.” We find this odd, akin to arguing that, e.g., sediment dynamics of glacioeustasy in the Pleistocene cannot apply to glacioeustasy that operated in the Pennsylvanian. Processes can apply across time, as long as the tenets of uniformity of process (uniformitarianism) are followed. Wilson and Schieber (2024) then focus on three main arguments to challenge the validity of our hypothesis for the Late Devonian in particular.Regarding the issue of an authigenic or detrital origin for the silica, we recognize that Schieber and his collaborators have extensive experience with mudstone petrography and petrology, are aware of and respect their work documenting diagenetic silica in mudstones, and indeed acknowledge in our paper the pervasive presence of diagenetic and biogenic silica in the Woodford Shale. For example, Figure 5B in McGlannan et al. (2022) illustrates the rhythmic, thin, chert-like beds in the Woodford Shale. Wilson and Schieber note that they have studied samples from the same sites we studied and found diagenetic silica. We do not doubt this. Owing to the common presence of diagenetic silica, we preferentially avoided silica-rich facies and predominantly sampled laminated shale facies. Wilson and Schieber (2024) suggest that we generated sand- and silt-size particles “upon crushing–processing” but, as we detailed in our paper, “Samples were gently crushed with a ceramic mortar and pestle to pea-size gravel to accelerate chemical reactions, then rinsed with distilled water and sieved at 250 μm to remove any fines generated during crushing” that might be erroneously incorporated in the grain-size analyses. Of 19 Woodford Shale samples, 12 were selected for particle-size measurement after smear-slide analysis to verify disaggregation and presence of a preponderance of detrital material (Supplemental File 3 and Fig. 6A in McGlannan et al. 2022), which included not only quartz, but minor feldspar and even (rare) accessory minerals such as zircon. We acknowledge that, despite our e","PeriodicalId":17044,"journal":{"name":"Journal of Sedimentary Research","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-02-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140036381","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}
Katherine L. Maier, Lorna J. Strachan, Stephanie E. Tickle, A. Orpin, S. Nodder, Jamie Howarth
The 2016 Mw7.8 Kaikōura Earthquake in Aotearoa New Zealand provides an opportunity to test widely applied turbidite sedimentation models because it triggered a co-seismic turbidity current. The resultant Kaikōura event bed (KEB), interpreted as a turbidite, is sampled for approx. 1300-km down-flow along the depositional system. Sediment core lithologies, computed tomography (CT), and particle-size data are used to test event-bed thickness, silt content, facies distribution and stacking patterns against the foundations of the turbidite conceptual model of Bouma (1962). KEB thickness is variable to approx. 100 km down-flow distance and attains a maximum thickness at approx. 700 km down-flow distance before thinning distally, similar to the predicted bell-shaped proximal to distal trend. Silt content is high throughout the KEB from canyon to fan. The KEB is dominated by laminated Td facies and Te facies that evolve down-system from laminated, then graded, to homogenous muds. CT and granulometry data ar e key to differentiating subtle density and textural variations within fine-grained deposits and reveal that KEB Td and Te facies in the KEB that are often not preserved or readily observed in older deposits. The KEB highlights a fine-grained sedimentary system that contrasts with more widely studied sandy turbidite basins. In particular, the KEB example reveals that Td and Te facies are ubiquitous in this fine-grained, silt-rich system. A varied conceptual model developed from the KEB may be applicable to many modern deep-sea turbidite systems and crucial for understanding present-day particulate transport to the deep sea and interpreting evidence from the stratigraphic record.
{"title":"Testing turbidite conceptual models with the Kaikōura Earthquake co-seismic event bed, Aotearoa New Zealand","authors":"Katherine L. Maier, Lorna J. Strachan, Stephanie E. Tickle, A. Orpin, S. Nodder, Jamie Howarth","doi":"10.2110/jsr.2023.115","DOIUrl":"https://doi.org/10.2110/jsr.2023.115","url":null,"abstract":"The 2016 Mw7.8 Kaikōura Earthquake in Aotearoa New Zealand provides an opportunity to test widely applied turbidite sedimentation models because it triggered a co-seismic turbidity current. The resultant Kaikōura event bed (KEB), interpreted as a turbidite, is sampled for approx. 1300-km down-flow along the depositional system. Sediment core lithologies, computed tomography (CT), and particle-size data are used to test event-bed thickness, silt content, facies distribution and stacking patterns against the foundations of the turbidite conceptual model of Bouma (1962). KEB thickness is variable to approx. 100 km down-flow distance and attains a maximum thickness at approx. 700 km down-flow distance before thinning distally, similar to the predicted bell-shaped proximal to distal trend. Silt content is high throughout the KEB from canyon to fan. The KEB is dominated by laminated Td facies and Te facies that evolve down-system from laminated, then graded, to homogenous muds. CT and granulometry data ar e key to differentiating subtle density and textural variations within fine-grained deposits and reveal that KEB Td and Te facies in the KEB that are often not preserved or readily observed in older deposits. The KEB highlights a fine-grained sedimentary system that contrasts with more widely studied sandy turbidite basins. In particular, the KEB example reveals that Td and Te facies are ubiquitous in this fine-grained, silt-rich system. A varied conceptual model developed from the KEB may be applicable to many modern deep-sea turbidite systems and crucial for understanding present-day particulate transport to the deep sea and interpreting evidence from the stratigraphic record.","PeriodicalId":17044,"journal":{"name":"Journal of Sedimentary Research","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140446043","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}
M. Martini, Mildred Zepeda Martínez, Laura Mori, Fernando Núñez-Useche, Maria Patricia Velasco de León, Luigi Solari
The mineral and chemical composition of clastic deposits is commonly used as a proxy for reconstructing the climatic history of the Earth. A mineralogical and chemical study of clastic deposits from the Jurassic Tlaxiaco basin of southern Mexico illustrates that the entire sedimentary system in which detritus is generated, subaerially transported and deposited exerts a major control on the composition of sedimentary rocks, placing some constraints on the use of mineral and chemical indices as paleoclimatic proxies. Since clastic deposits of the Tlaxiaco basin were formed under similar humid climatic conditions, but in sedimentary systems with different topography and transport histories, they represent a natural laboratory for testing the control that these parameters exert on the composition of clastic rocks. Our petrographic and chemical results show that, in sedimentary systems associated with low relief and in which detritus had the possibility of being temporarily stored in floodplains and meander ing bars, parent rocks and the derivative detritus interacted with weathering fluids over a long time, producing clastic deposits with composition that is representative of weathering conditions and climate of the region. On the other hand, in environments associated with steep and tectonically active relief, the rates of sediment transport and burial exceed the rate at which weathering can generate detritus, producing sedimentary deposits with composition that largely underestimates potential weathering and provide unreliable information on climate. Mineral and chemical indices should be considered as reliable paleoclimate proxies only when sedimentological data indicate that the sedimentary system allowed sediment interaction with weathering fluids over a long time.
{"title":"The influence of topography and transport history on the composition of clastic deposits from the Jurassic Tlaxiaco basin, southern Mexico: Limitations on the use of mineral and chemical indices as proxies for paleoclimate","authors":"M. Martini, Mildred Zepeda Martínez, Laura Mori, Fernando Núñez-Useche, Maria Patricia Velasco de León, Luigi Solari","doi":"10.2110/jsr.2023.087","DOIUrl":"https://doi.org/10.2110/jsr.2023.087","url":null,"abstract":"The mineral and chemical composition of clastic deposits is commonly used as a proxy for reconstructing the climatic history of the Earth. A mineralogical and chemical study of clastic deposits from the Jurassic Tlaxiaco basin of southern Mexico illustrates that the entire sedimentary system in which detritus is generated, subaerially transported and deposited exerts a major control on the composition of sedimentary rocks, placing some constraints on the use of mineral and chemical indices as paleoclimatic proxies. Since clastic deposits of the Tlaxiaco basin were formed under similar humid climatic conditions, but in sedimentary systems with different topography and transport histories, they represent a natural laboratory for testing the control that these parameters exert on the composition of clastic rocks. Our petrographic and chemical results show that, in sedimentary systems associated with low relief and in which detritus had the possibility of being temporarily stored in floodplains and meander ing bars, parent rocks and the derivative detritus interacted with weathering fluids over a long time, producing clastic deposits with composition that is representative of weathering conditions and climate of the region. On the other hand, in environments associated with steep and tectonically active relief, the rates of sediment transport and burial exceed the rate at which weathering can generate detritus, producing sedimentary deposits with composition that largely underestimates potential weathering and provide unreliable information on climate. Mineral and chemical indices should be considered as reliable paleoclimate proxies only when sedimentological data indicate that the sedimentary system allowed sediment interaction with weathering fluids over a long time.","PeriodicalId":17044,"journal":{"name":"Journal of Sedimentary Research","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139441906","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}
Saeed Khan, Brent Wilson, Ryan Ramsook, Hasley Vincent
The geomorphology and sedimentology of the Nariva River tidal-inlet complex, a microtidal fluvially influenced tidal-inlet complex, was analyzed. The complex comprises a recurved spit, an ebb-tidal channel, and an ebb-tidal delta. Morphological trends in the spatio-temporal evolution of the inlet complex were observed and recorded from Google Earth™ timelapse satellite images taken from 2003 to 2019. The two-dimensional internal architecture of the inlet complex and the sedimentary succession of the recurved spit, an ebb spit, the swash platform (of the ebb-tidal delta), a mouth bar (associated with the wet-season river-dominated inlet complex erosion), the ebb-tidal channel, and the adjacent foreshore were observed and documented from six shallow sedimentary cores.The Nariva River inlet width ranges from 17 to 40 m through its seasonal evolution, has a tidal prism of ∼ 2.17 × 105 m3, a cross-sectional area of 29.52 m2, and a depth ∼ 1.4 m (calculated at peak dry season near the inlet throat). The inlet complex undergoes an annual geomorphological evolution linked to the seasonally induced migration of the fluvial-to-marine transition zone (FMTZ). Increased fluvial discharge during the wet and hurricane seasons results in the basinward migration of the FMTZ rendering the inlet river dominated and resulting in the erosion of the inlet complex. During the dry season, low fluvial discharge, tidal dominance, and fair-weather conditions promote sedimentation in the inlet and the redevelopment of the inlet complex. The inlet has a complex (CX) internal architecture (fill pattern) defined by the laterally migrating recurved spit and ebb spit on their updrift margin, and conformable, mounded elements on their downdrift (e.g., mouth bar, swash platform, and foreshore). Two sedimentary successions were developed for ebb-tidal-delta deposits: off-axis of the ebb-tidal channel and on-axis. The off-axis succession is considerably similar to the adjacent foreshore-to-shoreface succession which can pose a challenge when attempting to identify these deposits in the rock record. The on-axis succession, however, despite thickness variability, showed a positive correlation to studied mesotidal tide-dominated inlet successions.
{"title":"THE MORPHODYNAMICS AND SEDIMENTOLOGY OF A SEASONALLY CONTROLLED MICROTIDAL TIDAL INLET: THE NARIVA RIVER TIDAL INLET, COCOS BAY, TRINIDAD","authors":"Saeed Khan, Brent Wilson, Ryan Ramsook, Hasley Vincent","doi":"10.2110/jsr.2022.041","DOIUrl":"https://doi.org/10.2110/jsr.2022.041","url":null,"abstract":"The geomorphology and sedimentology of the Nariva River tidal-inlet complex, a microtidal fluvially influenced tidal-inlet complex, was analyzed. The complex comprises a recurved spit, an ebb-tidal channel, and an ebb-tidal delta. Morphological trends in the spatio-temporal evolution of the inlet complex were observed and recorded from Google Earth™ timelapse satellite images taken from 2003 to 2019. The two-dimensional internal architecture of the inlet complex and the sedimentary succession of the recurved spit, an ebb spit, the swash platform (of the ebb-tidal delta), a mouth bar (associated with the wet-season river-dominated inlet complex erosion), the ebb-tidal channel, and the adjacent foreshore were observed and documented from six shallow sedimentary cores.The Nariva River inlet width ranges from 17 to 40 m through its seasonal evolution, has a tidal prism of ∼ 2.17 × 105 m3, a cross-sectional area of 29.52 m2, and a depth ∼ 1.4 m (calculated at peak dry season near the inlet throat). The inlet complex undergoes an annual geomorphological evolution linked to the seasonally induced migration of the fluvial-to-marine transition zone (FMTZ). Increased fluvial discharge during the wet and hurricane seasons results in the basinward migration of the FMTZ rendering the inlet river dominated and resulting in the erosion of the inlet complex. During the dry season, low fluvial discharge, tidal dominance, and fair-weather conditions promote sedimentation in the inlet and the redevelopment of the inlet complex. The inlet has a complex (CX) internal architecture (fill pattern) defined by the laterally migrating recurved spit and ebb spit on their updrift margin, and conformable, mounded elements on their downdrift (e.g., mouth bar, swash platform, and foreshore). Two sedimentary successions were developed for ebb-tidal-delta deposits: off-axis of the ebb-tidal channel and on-axis. The off-axis succession is considerably similar to the adjacent foreshore-to-shoreface succession which can pose a challenge when attempting to identify these deposits in the rock record. The on-axis succession, however, despite thickness variability, showed a positive correlation to studied mesotidal tide-dominated inlet successions.","PeriodicalId":17044,"journal":{"name":"Journal of Sedimentary Research","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139055816","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}
In this study, we present a detailed investigation of C-O-S-Sr isotope systematics and elemental analysis of secondary sulfates and associated host rock carbonates of Cambrian to Devonian sedimentary successions along the eastern flank of the Michigan Basin, Ontario. This study evaluates the diagenetic evolution of pore fluids and their sources in fracture-fill and replacement sulfate minerals within low-permeability carbonate units in the Michigan Basin. Secondary sulfates, represented by gypsum and anhydrite, contain various petrographic types, represented by vug- and fracture-filling fibrous anhydrite in the Cambrian (δ18O vary between 16.8 to 17.6 permil VPDB and δ 34S 28.3 to 29.0 permil CDT, 87Sr/86Sr ratios vary from 0.70834 to 0.70991, respectively) and Ordovician fibrous anhydrite (δ18O 16.8 permil, δ 34S 28.2 permil, 87Sr/86Sr ratios 0.70829). These phases display mainly uniform REE patterns with Y/Ho and Zr/Hf ratios, flat La*, Gd*, and Y* and enriched LREEs. Idiotopic satin-spar δ18O values vary between 4.0 and 8.3 permil, δ 34S 23.4 and 31.4 δ with 87Sr/86Sr ratios 0.70816-0.70866), xenotopic porphyroblast gypsum δ18O value vary between 4.5 and 13.3 permil, δ34S 22.6 to 33.1 permil with 87Sr/86Sr ratios of 0.70850-0.70880, alabastrine gypsum δ18O values vary between 4.2 and 11.7 permil, δ34S 23.1 to 26.9 permil with 87Sr/86Sr ratios of 0.70816-0.70876) and felted anhydrite δ18O values of 11.1 permil, δ 34S 27.4 permil with 87Sr/86Sr ratio of 0.70849). These geochemical proxies suggest a comparable sulfate-rich source for both age groups under similar geochemical conditions. Gypsum in the Silurian Salina Group display a wide range of REE values with Y/Ho, and Zr/Hf ratios, Nd/YbN and Pr/YbN, flat to strong Ce/Ce*, and flat to strong Eu/Eu* anomaly, Gd/LaN and Tb/LaN, Sm/LaN). These sulfates formed at burial from fluids of variable isotopic, chemical composition and temperatures. The sources of these fluids range from brines migrating from a deeper part of the basin forming anhydrite in the Cambrian and Ordovician sequences which were also affected by dolomitization and later hydrothermal fluid influx, to rehydration of gypsum at shallower burial depths and affected by salt dissolution and incursion of meteoric water during and following the Alleghenian orogeny.
{"title":"Diagenetic evolution of secondary evaporites and associated host rock dolostones in the Huron Domain (Michigan Basin): insights from petrography, geochemistry, and C-O-S-Sr isotopes","authors":"I. Al-Aasm, Richard Crowe, M. Tortola, M. Özyurt","doi":"10.2110/jsr.2023.102","DOIUrl":"https://doi.org/10.2110/jsr.2023.102","url":null,"abstract":"In this study, we present a detailed investigation of C-O-S-Sr isotope systematics and elemental analysis of secondary sulfates and associated host rock carbonates of Cambrian to Devonian sedimentary successions along the eastern flank of the Michigan Basin, Ontario. This study evaluates the diagenetic evolution of pore fluids and their sources in fracture-fill and replacement sulfate minerals within low-permeability carbonate units in the Michigan Basin. Secondary sulfates, represented by gypsum and anhydrite, contain various petrographic types, represented by vug- and fracture-filling fibrous anhydrite in the Cambrian (δ18O vary between 16.8 to 17.6 permil VPDB and δ 34S 28.3 to 29.0 permil CDT, 87Sr/86Sr ratios vary from 0.70834 to 0.70991, respectively) and Ordovician fibrous anhydrite (δ18O 16.8 permil, δ 34S 28.2 permil, 87Sr/86Sr ratios 0.70829). These phases display mainly uniform REE patterns with Y/Ho and Zr/Hf ratios, flat La*, Gd*, and Y* and enriched LREEs. Idiotopic satin-spar δ18O values vary between 4.0 and 8.3 permil, δ 34S 23.4 and 31.4 δ with 87Sr/86Sr ratios 0.70816-0.70866), xenotopic porphyroblast gypsum δ18O value vary between 4.5 and 13.3 permil, δ34S 22.6 to 33.1 permil with 87Sr/86Sr ratios of 0.70850-0.70880, alabastrine gypsum δ18O values vary between 4.2 and 11.7 permil, δ34S 23.1 to 26.9 permil with 87Sr/86Sr ratios of 0.70816-0.70876) and felted anhydrite δ18O values of 11.1 permil, δ 34S 27.4 permil with 87Sr/86Sr ratio of 0.70849). These geochemical proxies suggest a comparable sulfate-rich source for both age groups under similar geochemical conditions. Gypsum in the Silurian Salina Group display a wide range of REE values with Y/Ho, and Zr/Hf ratios, Nd/YbN and Pr/YbN, flat to strong Ce/Ce*, and flat to strong Eu/Eu* anomaly, Gd/LaN and Tb/LaN, Sm/LaN). These sulfates formed at burial from fluids of variable isotopic, chemical composition and temperatures. The sources of these fluids range from brines migrating from a deeper part of the basin forming anhydrite in the Cambrian and Ordovician sequences which were also affected by dolomitization and later hydrothermal fluid influx, to rehydration of gypsum at shallower burial depths and affected by salt dissolution and incursion of meteoric water during and following the Alleghenian orogeny.","PeriodicalId":17044,"journal":{"name":"Journal of Sedimentary Research","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138623116","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 modern Niger Delta has long been classified as a mixed tide-, wave- and fluvial-influenced delta. Still, no detailed studies have quantified the relative proportions of formative processes and facies. This work presents the first quantitative estimate of the relative influence of formative processes in Miocene deposits based on core data from the Greater Ughelli, Central and Coastal Swamp depositional belts of the Niger Delta Basin. Facies analysis of 288.2 m of core from 4 wells shows approximately 53% tidal facies, 33% fluvial facies and 14% wave-formed facies, indicating deposition in a prograding tide-dominated, fluvial- and wave-influenced delta. Cores from the Greater Ughelli and Central Swamp depobelts exhibit coarsening upwards, prograding deltaic facies successions overlain by fluvial mudstone. Tidal deposits in the Coastal Swamp depobelt show coarsening upwards prograding deltaic facies successions with well-developed tidal bundles indicating periodic deposition. The basal part of these facies successions also reveals repeated floods characterised by slump and load structures and dewatering features. Delta plain and delta front-prodeltaic facies associations are identified based on physical sedimentary and biological structures. The delta plain facies association consists of weakly bioturbated mudstone, fissile mudstone, and coarse-pebbly stratified sandstone facies with sparse trace fossils. The delta front-prodeltaic facies association contains muddy and sandy heteroliths, stratified, medium and coarse-grained, cross-bedded sandstone, and convoluted mudstone facies. The facies vary but characteristically contain trace fossil assemblages of the recently proposed Rosselia and Phycosiphon Ichnofacies, indicating delta front and prodeltaic settings, respectively. Variability in the facies is determined by the relative influence of hydrodynamic processes (tide, wave, and fluvial), variations in physicochemical stress, and the episodic character of deposition. In addition, based on the relative influence of each hydrodynamic processes, the facies differ through the successions, sometimes subtly.
{"title":"Quantifying a tide-dominated, fluvial-wave influenced delta in Miocene facies of the Niger Delta Basin","authors":"Sunny C. Ezeh, J. Bhattacharya","doi":"10.2110/jsr.2023.055","DOIUrl":"https://doi.org/10.2110/jsr.2023.055","url":null,"abstract":"The modern Niger Delta has long been classified as a mixed tide-, wave- and fluvial-influenced delta. Still, no detailed studies have quantified the relative proportions of formative processes and facies. This work presents the first quantitative estimate of the relative influence of formative processes in Miocene deposits based on core data from the Greater Ughelli, Central and Coastal Swamp depositional belts of the Niger Delta Basin. Facies analysis of 288.2 m of core from 4 wells shows approximately 53% tidal facies, 33% fluvial facies and 14% wave-formed facies, indicating deposition in a prograding tide-dominated, fluvial- and wave-influenced delta. Cores from the Greater Ughelli and Central Swamp depobelts exhibit coarsening upwards, prograding deltaic facies successions overlain by fluvial mudstone. Tidal deposits in the Coastal Swamp depobelt show coarsening upwards prograding deltaic facies successions with well-developed tidal bundles indicating periodic deposition. The basal part of these facies successions also reveals repeated floods characterised by slump and load structures and dewatering features. Delta plain and delta front-prodeltaic facies associations are identified based on physical sedimentary and biological structures. The delta plain facies association consists of weakly bioturbated mudstone, fissile mudstone, and coarse-pebbly stratified sandstone facies with sparse trace fossils. The delta front-prodeltaic facies association contains muddy and sandy heteroliths, stratified, medium and coarse-grained, cross-bedded sandstone, and convoluted mudstone facies. The facies vary but characteristically contain trace fossil assemblages of the recently proposed Rosselia and Phycosiphon Ichnofacies, indicating delta front and prodeltaic settings, respectively. Variability in the facies is determined by the relative influence of hydrodynamic processes (tide, wave, and fluvial), variations in physicochemical stress, and the episodic character of deposition. In addition, based on the relative influence of each hydrodynamic processes, the facies differ through the successions, sometimes subtly.","PeriodicalId":17044,"journal":{"name":"Journal of Sedimentary Research","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138612153","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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