Depositional Record最新文献

{"title":"Reply to the discussion and comments of Azerêdo et al. (2023) and Schneider et al. (2023) on the paper by Magalhães et al. ‘Middle Jurassic multi-scale transgressive–regressive cycles: An example from the Lusitanian Basin’, The Depositional Record, 9, 174–202","authors":"Antonio J. C. Magalhães, Gerson J. S. Terra, Felipe Guadagnin, Daniel G. C. Fragoso, Mirian C. Menegazzo, Nuno L. A. Pimentel, Sissa Kumaira, Gerson Fauth, Alessandra Santos, David K. Watkins, Mauro D. R. Bruno, Daiane Ceolin, Simone Baecker-Fauth, Guilherme P. R. Gabaglia, Washington L. E. Teixeira, Francisco P. Lima-Filho","doi":"10.1002/dep2.254","DOIUrl":"10.1002/dep2.254","url":null,"abstract":"<p>We want to acknowledge the comments about our recently published paper. The exchange of ideas, data and interpretation improves our knowledge and is the right way to discuss science's advances.</p><p>This reply considers the points raised by Azerêdo et al. (<span>2023</span>) and Schneider et al. (<span>2023</span>). In both manuscripts, these authors raised many issues about sedimentological and stratigraphic aspects that can be separated into two groups: (a) those related to the age of the studied succession; and (b) those assigning the studied succession to the Candeeiros Formation.</p><p>There is a long tradition of using macropalaeontology in the Lusitanian Basin, and many authors have used macrofossils as palaeoenvironmental indicators and to date sedimentary deposits. However, except for ammonoids, micropalaeontology data are much more accurate than those from corals or bivalves, for example. This is particularly important in the Consolação–São Bernardino succession because of the lack of micropalaeontological and biostratigraphical studies.</p><p>It is noteworthy that Magalhães et al. (<span>2023</span>) presented a hitherto unpublished micropalaeontological and biostratigraphical analysis of the Consolação–São Bernardino succession. The association of two fossil groups (calcareous nannofossil and dinoflagellates) support our biostratigraphic data, in which we performed taxonomic and biostratigraphic analyses with care and due importance. Hence, our analysis assures the age of the studied succession, which confirms the Bathonian<b>–</b>early Callovian age. Azerêdo et al. (<span>2023</span>) and Schneider et al. (<span>2023</span>) questioned our age assignments, but failed to present their micropalaeontological and biostratigraphical analysis for the same Consolação–São Bernardino succession. Moreover, our findings were integrated with facies analysis, ichnofacies, petrography and macrofossil content to support the proposed age. Azerêdo et al. (<span>2023</span>) and Schneider et al. (<span>2023</span>) have no doubts about the taxonomy presented, and their issues about our dating are based on reinterpretations of our data. They assumed that the literature had already defined the age of the studied succession, which we consider is beyond debate as a result of the new data. That paper acknowledged the previous studies in the Consolação-São Bernardino section. Still, the arguments by Azerêdo et al. (<span>2023</span>) and Schneider et al. (<span>2023</span>) are not based on micropalaeontological data collected in the Consolação-São Bernadino section, but rather on correlations with supposed chronoequivalent units that do not consider our new age. Their comments failed to include irrefutable evidence of the Upper Jurassic age based on micropalaeontological data from the Consolação–São Bernardino succession to contrast with dates presented by Magalhães et al. (<span>2023</span>).</p><p>New data bring new interpretations. Even though all i","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":"9 4","pages":"1167-1173"},"PeriodicalIF":2.4,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dep2.254","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135482482","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Record of palaeoclimate across the Cretaceous–Palaeogene boundary from palaeosols in the west-central San Juan Basin, New Mexico, USA","authors":"Lawrence H. Tanner,&nbsp;Spencer G. Lucas","doi":"10.1002/dep2.251","DOIUrl":"10.1002/dep2.251","url":null,"abstract":"<p>The mass extinction at the Cretaceous–Palaeogene boundary is widely attributed to sudden and severe climate changes forced by bolide impact and/or flood basalt volcanism. In terrestrial depositional settings, these changes may potentially be recorded by palaeosols. To test the ability of pedogenic features to record both long-term climate and shorter-term changes preceding and following the Cretaceous–Palaeogene extinction event, palaeosols in the Upper Cretaceous (Maastrichtian) Naashoibito Member of the Ojo Alamo Formation and the lower Palaeocene (Danian) Nacimiento Formation in the San Juan Basin of north-western New Mexico, USA, were examined, including data from previous studies. The fine-grained facies of the Naashoibito Member comprises grey to greenish-grey and red-banded mudstones displaying pedogenic features including colour mottling, root traces, cutans, ped fabrics, pedogenic slickensides and calcareous nodules. Aside from a high-chroma horizon at the formation base, palaeosols in the lower Nacimiento Formation are broadly similar to those observed in the Naashoibito Member. Lateral and vertical variability of the pedogenic features between correlated sections suggest that soil hydrology varied spatially and temporally from very saturated to seasonally well-drained, with temporal variations controlled by basin sedimentation rates. Abrupt and/or catastrophic climate events precisely at the Cretaceous–Palaeogene boundary are not recorded due to an unconformity at the top of the Naashoibito Member. However, the presence of kaolinite in the clay mineral assemblage of the Nacimiento Formation, particularly near the formation base, but not in the Naashoibito Member, indicates episodic warmth and short (10⁴ years) intervals of more intense weathering conditions during the very early Danian as compared to the late Maastrichtian. Aside from short warm intervals, the overall palaeoclimate during deposition of both formations was warm and consistently subhumid to humid and seasonal, suggesting no substantial long-term (10⁵–10⁶) climate change took place across the Cretaceous–Palaeogene boundary in the San Juan Basin.</p>","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":"9 4","pages":"1131-1152"},"PeriodicalIF":2.4,"publicationDate":"2023-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dep2.251","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44824673","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Resolving tsunami wave dynamics: Integrating sedimentology and numerical modelling","authors":"Jon Hill,&nbsp;Graham Rush,&nbsp;Jeff Peakall,&nbsp;Michael Johnson,&nbsp;Luke Hodson,&nbsp;Natasha L. M. Barlow,&nbsp;Elisabeth T. Bowman,&nbsp;W. Roland Gehrels,&nbsp;David M. Hodgson,&nbsp;Georges Kesserwani","doi":"10.1002/dep2.247","DOIUrl":"10.1002/dep2.247","url":null,"abstract":"<p>Tsunamis are a major hazard along many of the world's coastlines. To understand the impact of these events, a sufficiently long record of previous events is needed, which can be provided by their sedimentary deposits. A number of past events have left extensive sedimentary deposits that can be used to understand the hydrodynamics of the tsunami. The <i>ca</i> 8.15 ka Storegga submarine slide was a large, tsunamigenic mass movement off the coast of Norway. The resulting tsunami had estimated run-up heights of around 10 to 20 m on the Norwegian coast, over 30 m in Shetland and 3 to 6 m on the Scottish mainland coast. New cores were taken from the Ythan Valley in North-East Scotland, where Storegga tsunami deposits have previously been found. High-resolution sedimentary analyses of the cores, combined with statistical (changepoint) analysis, shows signatures of multiple waves. Moreover, detailed CT scans of the erosional basal surface reveal sole marks called skim marks. Taken in conjunction with the grain size and sedimentary fabric characteristics of the tsunami deposits, this indicates that the flow exhibited a high-concentration basal component, with an initial semi-cohesive phase and that deposition was dominantly capacity driven. A multiple wave hypothesis is tested by creating a high-resolution numerical model (metre-scale) of the wave inundation, coupled to a previously published regional model. The inundation model confirms that multiple waves passed over the site in agreement with the sedimentological analysis. The sensitivity of the model to the reconstructed palaeocoastal geomorphology is quantitatively explored. It is concluded that local palaeogeomorphological reconstruction is key to understanding the hydrodynamics of a tsunami wave group in relation to its sedimentary deposit. Combining sedimentological data with high-resolution inundation modelling is a powerful tool to help interpret the sedimentary record of tsunami events and hence to improve knowledge of their risks.</p>","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":"9 4","pages":"1046-1065"},"PeriodicalIF":2.4,"publicationDate":"2023-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dep2.247","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44710204","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Timing of the initiation and duration of the Cretaceous extensional regime in South-east China: Constraints from growth strata in terrigenous basins","authors":"Xinqi Yu,&nbsp;Jun Hu,&nbsp;Wei Li,&nbsp;Kun Liu,&nbsp;Ran Hao","doi":"10.1002/dep2.250","DOIUrl":"10.1002/dep2.250","url":null,"abstract":"<p>There has been no consensus yet regarding the precise initial timing and duration of the late Mesozoic extensional tectonics in the South-eastern China Block. This work focusses on the growth strata of the Early Cretaceous red beds in the South-eastern China Block to determine the late Mesozoic tectonics and the precise timing of the initiation and duration of extensional tectonics in this area. Field observation of several terrigenous basins shows that the dip angles of the Cretaceous red beds have varied from moderate to gentle from basin edges to interiors (or centres). The visible and estimated thickness within a single bed increases slightly downwards from the upper to the lower part. These characteristics indicate that the sedimentary area of these beds has undergone an extensional process with expansion and deepening of the sedimentary basins. Rotation of the border surfaces (limbs) and downward warping of the hanging walls or retreat of the footwalls of listric normal faults causes three types of extensional growth (or syntectonic) strata in the deposits of different basins. Dating of the volcanic rocks related to the growth beds reveals that the sedimentary basins were enlarged and deepened when the Early Cretaceous strata were deposited in the South-eastern China Block from <i>ca</i> 140 to 137 Ma. Regionally, under the influence of Palaeo-Pacific plate rollback since <i>ca</i> 140 Ma, the South-eastern China Block stress field has led to lithospheric uplift and pull-apart structures near the surface, causing the half-graben basins to receive sedimentation. Although the extensional event was interrupted by a short compressional event during 120 to 105 Ma, with the oceanward retreat of the trench, the area of extension gradually enlarged and rejuvenated south-eastwards until the end of the Cretaceous. This Cretaceous extension event of the South-eastern China Block must belong to a worldwide geological event with global significance.</p>","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":"10 1","pages":"4-32"},"PeriodicalIF":2.4,"publicationDate":"2023-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dep2.250","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49446829","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Depositional architecture and sequence stratigraphic framework of the fluvio-lacustrine Ash Shumaysi Formation, Jeddah-Makkah Region, Saudi Arabia: Implications for climatic and tectonic changes in a local-scale sub-basin","authors":"Faisal A. Alqahtani,&nbsp;Murad R. Abdulfarraj,&nbsp;Hamdalla A. Wanas","doi":"10.1002/dep2.248","DOIUrl":"10.1002/dep2.248","url":null,"abstract":"<p>This study aims to interpret and document the depositional architecture styles and sequence stratigraphic framework of the Ash Shumaysi Formation in the Jeddah-Makkah region, the west-central part of Saudi Arabia, and presents an example of rarely discussed, local-scale sub-basins (half grabens). It also shows the relationships between synchronous sedimentary processes and pre, syn and post-rift conditions. The described lithofacies and their facies associations indicate the presence of seven architectural depositional styles: proximal-distal braided fluvial, meandering fluvial (point bar), crevasse splay, floodplain, estuarine and lacustrine. A proposed depositional model for the Ash Shumaysi Formation is drawn. The Ash Shumaysi Formation forms a second order depositional sequence, which is organised into two third order depositional sequences (sequences I and II) bounded by three sequence boundaries. Each third-order sequence encloses the low accommodation systems tract and high accommodation systems tract. The low accommodation systems tract represents the coarse-grained, braided-distal fluvial facies developed during low accommodation space associated with high sediment supply (high discharge). The high accommodation systems tract encloses the fine-grained deposits of point bar, estuarine and lacustrine facies that reflect the creation of significant accommodation space and low sediment supply (low discharge). Vertical and lateral variations of the inferred depositional architectural styles, sequences and systems tracts reflect that tectonic forces and climate are the main controlling factors during deposition of the Ash Shumaysi Formation, although base-level changes in response to sea-level changes cannot be ruled out.</p>","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":"9 4","pages":"1066-1094"},"PeriodicalIF":2.4,"publicationDate":"2023-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dep2.248","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48986679","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reconstruction of the Late Miocene to Pliocene continental succession of Samos Island: Palaeoenvironmental implications for the Eastern Aegean domain","authors":"Youri Hamon,&nbsp;Rémy Deschamps,&nbsp;Christian Gorini,&nbsp;Dimitris Sakellariou,&nbsp;Cédric Bailly,&nbsp;Tarik Kernif,&nbsp;Alina Bérénice Christ,&nbsp;Mathilde Adelinet,&nbsp;Jérôme Fortin","doi":"10.1002/dep2.249","DOIUrl":"10.1002/dep2.249","url":null,"abstract":"<p>On the Island of Samos (East Aegean region, Greece), two sedimentary basins are filled by thick continental series dated to the Late Miocene to Early Pliocene. A multidisciplinary study has been performed including (1) the definition of 21 sedimentary facies, (2) a review of the biological components and (3) carbon, oxygen and strontium stable isotope analyses. The succession is characterised by various depositional settings and hydrochemical compositions. Five main stages of basin evolution have been identified: (1) The Late Serravallian is marked by the development of alluvial fans and fan delta; (2) during the Lower Tortonian, isolated shallow lakes with variable salinity, from fresh to brackish, developed under warm and relatively humid conditions; (3) the Middle to Upper Tortonian is marked by the development of a large and deep lake with saline and alkaline waters, under colder and drier conditions; (4) the Latest Tortonian to Messinian period is represented by an ephemeral alluvial system, developed under a dry climate; (5) during the Zanclean, a palustrine and paludal wetland system, dominated by tufa carbonates, developed under moderately humid conditions. This succession is of particular interest for the reconstruction of the palaeoenvironmental evolution of the transition zone between the Mediterranean domain, and the Paratethys and circum-Paratethys areas. The geochemical data and the presence of flora (diatoms) and fauna (gastropods) of marine affinity suggest transient ingressions of marine-related water or groundwater inflows as early as the Lower Tortonian. The Samos succession records the complex interaction between the regional geodynamics and climate. The extensional regime of the Eastern Aegean zone generates subsidence, interrupted in the mid-Tortonian (9 Ma) by a brief compressive event and a major exposure of the basins. Furthermore, the Late Miocene progressive aridification, followed by a change to a more humid climate (Pliocene) is also a major driver of the sedimentation.</p>","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":"9 4","pages":"1095-1130"},"PeriodicalIF":2.4,"publicationDate":"2023-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dep2.249","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43386389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Carbonate submarine fan deposits of the Mississippian Lake Valley Formation, Sacramento Mountains, New Mexico","authors":"James Bishop,&nbsp;Steve Bachtel,&nbsp;Jesse Thompson,&nbsp;Cody Miller,&nbsp;Brooks Ryan,&nbsp;Morgan Sullivan,&nbsp;Zane Jobe","doi":"10.1002/dep2.246","DOIUrl":"10.1002/dep2.246","url":null,"abstract":"<p>Deep-water carbonate deposition is relatively poorly understood but an area of vigorous research in academia and industry, where these deposits are a significant component of many unconventional petroleum reservoirs. Recent studies of modern deep-water carbonates have highlighted the wide variety of depositional processes, sediment types and resultant geomorphology; however, well-documented outcrops of ancient systems, their rock types and architecture are relatively sparse. The Mississippian Lake Valley Formation provides world-class exposures of slope-basinal carbonate deposits. The Tierra Blanca and Doña Ana members comprise submarine fans that are &gt;14 to 20 km in length, &gt;5 km wide, and exposed in strike and dip view, affording a unique opportunity to constrain the architecture, rock types and sedimentary processes. Tierra Blanca and Doña Ana sedimentation was dominated by crinoids shed from an up-dip platform and supplemented by sediments sourced locally from Waulsortian mounds. Depositional processes include turbidity flows, debris flows and hybrid sediment-gravity flows. The Tierra Blanca submarine fan thins towards its lateral flanks and distal fringe, where deposits become more mud-dominated, gravelly grain-supported flows are less common, and fewer beds have scoured bases. In proximal settings, bed tracing complemented by measured sections allow mapping of stratal surfaces and identification of stories, elements and complexes. The Tierra Blanca evolved from more unconfined to confined deposition. Point-sourced deposition of the Tierra Blanca fan required a funnelling mechanism, probably due to bathymetry created by Waulsortian mounds or possibly a platform margin re-entrant. Outcrop exposures illustrate that younger Doña Ana submarine fan deposits onlap onto, and compensationally stack with, the thickest portions of the antecedent Tierra Blanca fan. These outcrops illustrate both similarities and differences between carbonate and siliciclastic gravity flow deposits. Similarities include comparable deposit types, depositional processes and architecture; differences relate to hydrodynamics of carbonate grains, funnelling mechanisms for point-sourced deposits and sequence stratigraphic forcing.</p>","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":"9 4","pages":"1010-1045"},"PeriodicalIF":2.4,"publicationDate":"2023-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dep2.246","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48706200","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reevaluating the process regime in the Sego Sandstone: Sedimentological and ichnological evidence for an underemphasised fluvial signature","authors":"Marcello Gugliotta,&nbsp;Daniel S. Collins,&nbsp;James A. MacEachern,&nbsp;Narjess El Euch-El Koundi","doi":"10.1002/dep2.245","DOIUrl":"10.1002/dep2.245","url":null,"abstract":"<p>Rocks of coastal to shallow-marine origin are challenging to interpret owing to the complex interplay of various depositional processes. This study reevaluates the relative roles of fluvial, tidal and wave processes in the Upper Cretaceous Sego Sandstone (and subordinately in the underlying Buck Tongue) of the Book Cliffs, USA, a well-studied ancient coastal to shallow-marine succession. Detailed sedimentological and ichnological analyses were used to interpret a previously underemphasised riverine signature, consisting of centimetre- to decimetre-thick alternations of sandstone and heterolithic beds inferred to represent flood–interflood periods of variable river discharge. Recognition of a widespread fluvial-dominated signature across the studied units better agrees with other sedimentological and regional observations in the study area, such as high sandstone–mudstone ratios, largely unidirectional and seaward-oriented palaeocurrents, and modelled weak tidal conditions in the basin. When considering all of the sedimentological, ichnological and stratigraphic observations together with its regional depositional context, the Sego Sandstone/Buck Tongue system is better explained using a mixed-energy but fluvial-dominated deltaic model. This highlights an historical over-interpretation of tidal processes and subordinate wave processes in the Sego Sandstone and likely in similar units. The widely used approach that emphasises only certain sedimentary features in discerning the process regime from analysis of rocks of inferred coastal to shallow-marine origin is unrefined and may therefore underrepresent the actual complexity of these systems.</p>","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":"9 4","pages":"989-1009"},"PeriodicalIF":2.4,"publicationDate":"2023-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dep2.245","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46441742","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Flow depth estimates and avulsion behaviour in alluvial stratigraphy (Willwood Formation, Bighorn Basin, Wyoming, USA)","authors":"Brady Z. Foreman,&nbsp;Grace M. Sutherland,&nbsp;Delaney J. Todd,&nbsp;Kristopher D. Phillips,&nbsp;Anthony Semeraro","doi":"10.1002/dep2.243","DOIUrl":"10.1002/dep2.243","url":null,"abstract":"<p>The size and geometry of river channels play a central role in sediment transport and the character of deposition within alluvial basins across spatiotemporal scales spanning the initiation of grain movement to the filling of accommodation generated by subsidence. This study compares several different approaches to estimating palaeoflow depths from fluvial deposits in the early Palaeogene Willwood Formation of north-west Wyoming, USA. Fluvial story heights (<i>n</i> = 60) and mud plug thicknesses (<i>n</i> = 13) are statistically indistinguishable from one another and yield palaeoflow depth estimates of 4 to 6 m. The vertical relief on bar clinoforms (<i>n</i> = 112) yields smaller flow depths, by a factor of <i>ca</i> 0.3, with the exception that the largest bar clinoforms match story heights and mud plug estimates. This observation is consistent with modern river data sets that indicate unit bar clinoforms do not capture the reach-mean bank-full flow depths except in rare circumstances. Future studies should use story heights (i.e. compound bar deposits) and mud plugs to estimate bank-full flow depths in alluvial strata. Additionally, the thickness of multi-storied fluvial sandbodies (<i>n</i> = 102) and overbank cycles composed of paired crevasse splay and palaeosol deposits (<i>n</i> = 45) were compared. The two depositional units display statistically indistinguishable mean and median values. Building upon previous depositional models, these observations suggest basin rivers aggraded approximately one flow depth prior to major avulsion. This avulsion process generated widespread crevasse splay deposition across the floodplain. Once the main river channel stem was reestablished, overbank flooding and palaeosol development dominated floodplain settings. The depositional model implies river aggradation autogenically generated topography in the basin that was effectively filled during the subsequent avulsion. This constitutes a meso-timescale (10³–10⁴ years) compensational pattern driven by morphodynamics that may account for the high completeness of fossil and palaeoclimate records recovered from the basin.</p>","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":"9 4","pages":"935-958"},"PeriodicalIF":2.4,"publicationDate":"2023-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dep2.243","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41606405","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Bidirectional fabric evolution in Hamelin Pool microbialites, Shark Bay, Western Australia","authors":"Brooke E. Vitek,&nbsp;Erica P. Suosaari,&nbsp;Amanda M. Oehlert,&nbsp;Christophe Dupraz,&nbsp;Clément G. L. Pollier,&nbsp;R. Pamela Reid","doi":"10.1002/dep2.244","DOIUrl":"10.1002/dep2.244","url":null,"abstract":"<p>Hamelin Pool, Shark Bay, Western Australia hosts the world's largest and most extensive assemblages of living marine microbialites, comparable in size and shape to ancient structures found throughout the fossil record. Documented here are the internal fabrics of modern microbialites collected throughout Hamelin Pool. Mesoscale and microscale observations of microbialite polished slabs and thin section scans, optical microscopy and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy formed the basis for a fabric classification system that combines accretionary mat type with microfabric. Accretionary mat types included pustular, smooth, colloform, as well as ‘transitional’ mats that are a cross between pustular and smooth mats. Mapping of fabrics in 45 microbialite heads indicated bidirectional evolution. An upward progression of fabrics corresponded to changes in mat type as the head grew upward into shallower water. A downward evolution of microfabrics occurred as surface mats transitioned into the subsurface of the microbialite structure. Downward microfabric evolution occurred as a result of early taphonomic processes, and involved a progression from the original depositional architecture to subsequent stages of “Micritic Thickening”, and finally, “Cement Infilling”. The observed bidirectional evolution of microbialite microfabrics within Hamelin Pool offers a conceptual framework for the study of modern microbialites, not simply as the sole product of accretionary mat types but rather as the combined result of the activity of surface mats and their taphonomic evolution. Early taphonomic processes induce further lithification of the microbialites which may enhance preservation potential in the geological record.</p>","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":"9 4","pages":"959-988"},"PeriodicalIF":2.4,"publicationDate":"2023-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dep2.244","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43051252","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}