Abstract Carbonates formed by anaerobic oxidation of methane at localized seeps have been recognized in the rock record based on a list of criteria, including anomalous deposition within detrital facies, complex petrofabrics, seep‐endemic macrofauna and 13 C‐depleted isotopic signatures. While much emphasis has been placed on the latter, it is only one of several tools used for identification. This study reports on two different and rare limestone units in the forearc deposits of the Jurassic Bedford Canyon Formation in the Santa Ana Mountains, California (USA). Isolated, metre‐scale limestone pods were found to host abundant endemic Anarhynchia dimerelloid brachiopods and display diverse petrofabrics, including multiple generations of cements. However, the δ 13 C values of the petrofabrics ranged from −14.5 to 4.52‰ Vienna PeeDee Belemnite. These values are only slightly 13 C‐depleted relative to contemporaneous seawater, thus likely recording a stronger component of oceanic dissolved inorganic carbon than hydrocarbons. Additionally, although the petrofabrics are common for seeps (primary micrite, microbialite, pelsparite, intraclastic micrite; early isopachous and botryoidal cements and yellow calcite; late‐stage void‐filling spar), the isotopic values did not follow a predicted trend of increasing δ 13 C with paragenetic sequence. Pelsparite δ 13 C values ranged from −10.65 to −7.09‰ Vienna PeeDee Belemnite while coarse spar and vein cements ranged from −11.42 to −2.44‰ Vienna PeeDee Belemnite. Olistostromes composed of brecciated pelmicrite sourced from shallow fringing‐arc environments are typical of forearc settings. Olistostromes in the Bedford Canyon Formation contain much lower δ 13 C values than the more classically characterized seep deposits, ranging from −21.77 to −10.78‰ Vienna PeeDee Belemnite. While the original shallow‐water source may not have a been a confined seep, the low δ 13 C values require the incorporation of carbon sourced from the oxidation of localized hydrocarbons. Together, these findings recommend a reconsideration of the weight placed on δ 13 C values as the key criterion for distinguishing seeps in the rock record.

Russell S. Shapiro

Miquela Ingalls

Sedimentology

Challenges to the ancient methane seep search strategy: The Bedford Canyon Formation (Middle Jurassic, Santa Ana Mountains, California)

古代甲烷渗漏搜索策略的挑战：贝德福德峡谷组（中侏罗世，圣安娜山脉，加利福尼亚）

Abstract Research on the ichnology of brackish‐water environments began in the 1930s and has led to the identification of predictable infaunal patterns. Brackish‐water deposits characteristically display low‐diversity tracefossil assemblages consisting of both vertical and horizontal structures. These salinity‐reduced ecosystems are dominated by opportunistic euryhaline‐tolerant species. Osmoregulation‐related selective pressures lead to decreased diversity and an abundance of infaunal organisms. In environments with fluctuating or low salinity, fauna adopt r‐selected strategies and are characterized by rapid colonization dynamics, high population densities, elevated mortality rates and low‐diversity assemblages. Tides in brackish‐water settings contribute a plentiful food supply with tidal currents transporting marine‐sourced and terrestrially sourced organic matter that settles on the sediment–water interface during slack‐water periods. This increased food availability favours trophic generalists using various feeding strategies to exploit both intrastratal and surficial food resources. The ichnological characteristics of modern and ancient brackish‐water strata are used to propose the Teichichnus Ichnofacies; they are temporally and spatially recurrent and reflect the biology of brackish‐water settings. The Teichichnus Ichnofacies is recognized by reduced trace‐fossil diversity, smaller trace sizes, dominance of structures reflecting trophic generalist behaviours, sporadic distributions of ichnofossils, locally high bioturbation intensities and opportunistic colonization. This ichnofacies is characterized by trace fossils interpreted to be associated with surface deposit feeding, intrastratal deposit feeding and subordinate filter feeding.

Murray K. Gingras

James A. MacEachern

Shahin E. Dashtgard

Kerrie L. Bann

The <i>Teichichnus</i> Ichnofacies: Its neoichnological basis and identification in the rock record

《Teichichnus》遗迹相：其现代遗迹学基础与岩石记录中的识别

ABSTRACT The Yukon–Koyukuk Basin is a wide, triangular depression in northern Alaska that initiated as the consequence of the collision between an intraoceanic arc and the Arctic Alaska margin. It is bordered by the metamorphic terranes of the Seaward Peninsula, the Brooks Range and the Ruby Terrane. The Yukon–Koyukuk Basin is divided into two sub‐basins separated by remnants of the volcanic arc. Two different models have been suggested for its formation. One model interprets the Yukon–Koyukuk Basin to have formed during collision in a forearc–backarc setting, while the other favours an extensional regime that was active after the cessation of collision. To test the two models, ten sedimentary samples from the two stratigraphically lowest units cropping out along the middle reaches of the Koyukuk River were analysed. Point counting and Quantitative Evaluation of Minerals by Scanning Electron Microscopy (QEMSCAN ® ) are used to evaluate sedimentary provenance. This study also presents zircon U–Pb ages from three interbedded tuffaceous layers to better constrain the age of the units. The base of the succession indicates a volcanic source (enriched in clinopyroxene) deposited at ca 138.3 ± 0.8 Ma (2σ), while younger overlying strata are dominated by metamorphic input (enriched in garnet and epidote) reflecting the erosion of the surrounding metamorphic terranes at ca 112.6 ± 1.1 Ma (2σ). The application of a multi‐method provenance approach has been essential in constraining the formation and evolution of the northern Yukon–Koyukuk Basin. This is of significant importance for advancing the understanding of Alaskan geology and for providing insights into modern basins within analogous tectonic settings, such as the Banda Arc in Southeast Asia.

Simone Seminara

Victoria Pease

Jaime Toro

Jenny Omma

Provenance studies and basin evolution: Insight from the Yukon–Koyukuk Basin, Alaska

原产地研究与盆地演化：来自阿拉斯加育空-科尤库克盆地的启示

Abstract Shelves surrounding reefless volcanic islands usually host sediment that is considered to result mostly from erosion of pre‐existing volcanic rocks, with minor contributions from active volcanism and biogenic production. However, due to the scarcity of studies on volcanic islands, the way in which sediment is produced and deposited in these settings is still relatively poorly understood. In this study, a source‐to‐sink approach is used to understand how sediments on the southern shelf of the inactive volcanic island of Porto Santo (Madeira Archipelago) have formed. To achieve this aim, sediment texture, composition (carbon content) and morphoscopic characterization are integrated with acoustic information from the shelf (multibeam bathymetry, backscatter imagery and sediment thickness). Seafloor sediments are mostly moderately sorted sands with carbonate skeletal particles representing around 80% of the grains and minor volcaniclasts and aeolianite particles from inland subaerial erosion. Multibeam and seismic data allow recognizing some elongated erosive–depositional features that give insights into present‐day and past currents on the shelf. Additionally, an assessment of the subaerial sediment contribution to the shelf has been compared to the overall sediment volume present there. The findings indicate that the current sediment volume significantly exceeds the terrigenous supply, suggesting a significant primary biogenic carbonate production on the shelf. The sediment microscopic characterization supports this hypothesis, which leads to the conclusion that on low‐relief inactive volcanic islands, like Porto Santo, the contribution of carbonate factories to shelf sediment has a bigger role than previously considered.

Simone Innocentini

Rui Quartau

José Madeira

Daniele Casalbore

César Andrade

Ana Nobre Silva

Mário Cachão

Sandra Moreira

Rúben Santos

Joaquim Pombo

Aurora Rodrigues

Present‐day sedimentary processes on the shelves of inactive volcanic ocean islands: The case study of Porto Santo Island (Madeira Archipelago)

现今非火山海洋岛屿陆架的沉积过程：以波尔图桑托岛（马德拉群岛）为例

Abstract The Upper Ordovician (Katian) Neda Formation, a phosphatic ironstone, records a widespread but short‐lived shift to ferruginous waters across a vast epicontinental area. Lithofacies and stratigraphic reappraisal indicate that Neda ironstone deposition occurred on a storm‐dominated ramp when coastal upwelling emplaced eutrophic ferruginous waters that mixed with oxygenated surface water. This stimulated primary productivity and precipitated Fe‐(oxyhydr)oxides in the water column that formed phosphorous and iron‐rich mud. Remobilization of iron beneath the seafloor led to the syndepositional authigenic precipitation of P and Fe minerals in the sediment, preferentially coating grains and forming granular ironstone in the top few decimetres of the sediment. The top of the Neda Formation is a pronounced unconformity punctuated by laterite that formed as sea level fell during the Hirnantian Glaciation. The transition from oxygenated to ferruginous conditions that led to ironstone deposition is interpreted to have been caused by an increase in the equator‐to‐pole temperature gradient and concomitant reorganization of thermohaline circulation during the Katian. This intensified upwelling off the Laurentian margin with upwelled waters transported into the midcontinent where ironstone accumulated through the Sebree Trough. The Neda ironstone's deposition coincident with, and potentially caused by, the same drivers as global oceanographic and biotic change during the Late Ordovician both adds greater insight into the major changes in the oceans preceding the Late Ordovician Mass Extinction and Hirnantian Glaciation, and also furthers an emerging model tying ironstone deposition throughout the Phanerozoic to major Earth system events.

Edward J. Matheson

Jackson D. Malone

Peir K. Pufahl

Eric E. Hiatt

Late Ordovician ironstone and its relation to ocean redox instability, climate and glaciation

晚奥陶纪铁矿石及其与海洋氧化还原不稳定性、气候和冰川作用的关系

Abstract Intertidal environments are highly dynamic and exhibit both regular and periodic fluctuations in environmental parameters. The interplay of these parameters controls the distribution and abundance of infaunal organisms resulting in sporadic bioturbation distributions that are well‐documented but not fully understood. This study investigates topographic controls on infaunal distributions at East Beach in White Rock, British Columbia, Canada. East Beach is a sandy intertidal flat characterized by sand dunes that give rise to two alternating shore‐parallel subenvironments: topographically high dune crests and topographically low interdunes. The dunes remain relatively fixed in their position between major storm events, resulting in geographically stable subenvironments. Photogrammetric reconstructions of dune surfaces are used to characterize surface features and quantify invertebrate burrow openings along dune profiles. This is supplemented by X‐ray radiography and examinations of porewater and organic matter content from the two subenvironments. These results show a clear inverse relationship between burrow abundance and elevation at the dune scale, with the interdunes displaying significantly higher bioturbation intensities compared to dune crests. The burrow distributions appear to be strongly influenced by water saturation, presumably due to its role in controlling oxygen availability and preventing desiccation. This research provides insights into the local factors controlling infaunal distributions and the impact of palaeo‐topography on bioturbation, particularly in intertidal settings. Additionally, these data assist in interpreting heterogeneous bioturbation distributions in the sedimentary record, which are normally not interpreted due to a paucity of analogue models developed in modern environments.

Scott Melnyk

Cody N. Lazowski

Topographic controls on the distribution of bioturbation in an intertidal sandflat

潮间带沙坪生物扰动分布的地形控制

ABSTRACT Continental red beds are coloured by secondary Fe(III)‐oxy‐hydroxides (mainly hematite) which makes them excellent archives of ancient near‐surface redox conditions. However, colour is often treated as a subjective physical property, and opinions differ widely as to the environment and timing of colouration of the red beds. This study utilizes diffuse spectral reflectance to address the degree of reddening (hematitization) of the Siluro‐Devonian Old Red Sandstone representing a dryland fluvial system with abundant palaeo‐Vertisols, coinciding with the period of land colonization by vascular plants. The hematitization was studied along with the stratigraphy, facies, pedogenic features, petrology, element and Molybdenum isotope geochemistry. The mudstones and palaeosols are typically red while sandstones are often grey. The red colouration corresponds to approximately 30 to 36% of red band (625 to 700 nm) reflectance and high hematite to goethite ratios. The red sediments contain hematitized biotite, submicronic hematite in mudstone and sandstone matrix, and hematite cement in calcretes. The hematitization was synchronous with formation of pedogenic mudcracks, Vertic slickensides, calcretes, reduction spots, sometimes hydrodynamic reworking, and accompanied by local (grain‐scale) depletion in Fe(II), enrichment in Fe(III), and mobilization of U, V, As, Cu, Zn and Mo. It is estimated that the hematite growth was rapid (several hundred to thousand years) but the average sedimentation rates were low (approximately 3 to 10 cm/kyr). Erosion led to development of reactivation surfaces separating layers with contrasting hematite content and geochemistry. It is suggested that high rates of pedogenesis and low sedimentation rates favour the reddening and may represent an important control on the formation of continental red beds. Limited levels of soil waterlogging, and the published δ 13 C values (−9 to −12‰ Vienna Pee Dee Belemnite) of the pedogenic carbonate, might reflect the changes in the nature of the soil biomantle during the early Devonian land colonization by vascular plants.

Ondřej Bábek

Lukáš Ackerman

Daniel Šimíček

V. Paul Wright

Susan Marriott

Tomáš Pluháček

Salahaddin Shahrokhi

Hedvika Weinerová

Pedogenic continental red beds: How, why and when red? Redox geochemistry and quantitative colour analysis of the Old Red Sandstone, South Wales, UK

成土大陆红层：如何、为何及何时变红？英国南威尔士老红砂岩的氧化还原地球化学与定量颜色分析

ABSTRACT The lower Nama Group in southern Namibia contains trace fossils and soft‐bodied and biomineralized macro‐organisms from the terminal Ediacaran Period ( ca 550 to 539 Ma), offering insights into early metazoan evolution. Interpretation of the fossilized Nama Group organisms as being preserved in, or very close to, the environments in which they originally lived has yielded insights into organism feeding habits, reproduction and life histories. Sedimentological evidence presented here reveals that typical ‘Nama‐type’ Ediacaran macro‐fossils ( Cloudina , Ernietta , Pteridinium and Rangea ) in the Dabis and Zaris formations of the Witputz Sub‐basin seldom preserve organisms in life position in their original palaeoenvironments. Both soft‐bodied and biomineralizing organisms were transported in sediment gravity flows (debris flows, turbidity flows and transitional debris flow‐turbidity flow ‘hybrid’ event beds) or combined flow (hummocky cross‐strata) to their terminal environment of deposition in shoreface and offshore shelf settings. Transport has placed studied beds and their associated macro‐organisms in depositional settings detached from the original life habitat, with macro‐organisms sourced from shallower‐water, up‐slope environments. Integrated sedimentological and palaeontological data indicate that the Nama Group may not provide a high‐fidelity record of original Nama ecosystems. Individual macro‐organisms are clasts within beds, and can be horizontal, imbricated or chaotic in orientation. Transport can blend different communities at various scales (bed, outcrop and basin), complicating interpretations of life habitats, species interactions and taxon‐specific ecology, such as feeding behaviour and life position of organisms. Recognition of organism transport also impacts datasets used for comparing global Ediacaran fossil assemblages, with implications for tracking spatial and temporal patterns in early animal evolution.

Brennan O'Connell

William J. McMahon

Andreas Nduutepo

Paulina Pokolo

Helke Mocke

Sean McMahon

Catherine E. Boddy

Alexander G. Liu

Transport of ‘Nama’‐type biota in sediment gravity and combined flows: Implications for terminal Ediacaran palaeoecology

“Nama”型生物在沉积重力和复合流中的运输：对埃迪卡拉纪末期古生态学的启示

ABSTRACT The sedimentary fill of Gale crater on Mars is dominated by lacustrine strata that are the focus of investigations into surface processes, climate change and habitability early in the planet's history. This study focuses on the lower part of the explored portion of the Murray formation on Aeolis Mons (Mount Sharp) in the Pahrump Hills and Hartmann's Valley field areas. At Pahrump Hills, sedimentary features and geochemical attributes of exposed mudstones suggest accumulation in an underfilled lake basin in which lake levels, shorelines and salinities fluctuated greatly at various temporal scales. The immediately superjacent stratigraphic interval, designated by the rover team as the Hartmann's Valley member, has previously been interpreted as an aeolian‐deposited sandstone interval. This fresh examination of all available data, however, suggests that the Hartmann's Valley member is strongly dominated by the same mudstone facies that compose most of the underlying Pahrump Hills member. The one novel facies element encountered in the Hartmann's Valley member are undulose bedded to convex bodies of mudstone that are oriented roughly north–south, suggestive of sediment supply from a northern fluvial source. Mudstones analogous in scale and character to these undulose mudstones occur on Earth in multiple modern and ancient lacustrine successions, and are related to deposition of prodelta mud lobes. The mudstones of the Hartmann's Valley member record a continuation of the underfilled evaporitive lake system proposed previously for the underlying Pahrump Hills member but with somewhat more variable environmental conditions. Hartmann's Valley mudstones contain more abundant matrix CaSO 4 , suggesting more severe evaporitic conditions, whereas the interbedded undulose bedded mudstones signify intermittent freshening and buildout of mud‐dominated deltas into the lake. The textural similarities between Pahrump Hills and Hartmann's Valley strata suggest that the Gale lacustrine system operated at a stable depositional mode with similar environmental parameters during both stratigraphic intervals.

Juergen Schieber

Kevin M. Bohacs

David Bish

Max Coleman

Lucy Thompson

William Rapin

Zalmai Yawar

Evaporitic–lacustrine mudstone laminites and prodelta mudlobes – continuity and change in the Hartmann's Valley interval, Murray formation, Gale crater, Mars

蒸发盐湖泥岩纹层和前三角洲泥丘——火星盖尔陨石坑默里组哈特曼谷段中的连续性与变化

Abstract Large evaporite deposits, reaching several hundreds of metres of thickness, occur in many basins of our planet but remain poorly understood due to the absence of modern analogues. The origin of ancient evaporites and their highly variable sedimentation rates are often debated and ambiguous. The Danakil rift basin in northern Afar (Ethiopia) features several hundreds of metres of evaporites with deposition still continuing today and, as such, represents a unique modern analogue for older thick evaporite deposits. This study focuses on the multi‐proxy analysis of a 625 m long core from the central part of the basin. The core record, dominated by halite ( ca 60%) with subordinate clastic sediments ( ca 35%) and potash minerals ( ca 5%) reveals, for the first time, the Late Pleistocene to Recent geological and environmental history of the basin. Sediments experienced restricted marine conditions after the last Late Pleistocene marine incursion in the basin, followed by a hypersaline stage leading to the near‐desiccation of the basin with the deposition of thick halite and potash deposits. Subsequent recycling of marginal halite deposits by meteoric waters in lacustrine and salt pan environments significantly increased the evaporite thickness in the subsiding central part of the basin. These findings have implications for the understanding of older thick evaporite deposits that formed in similar depositional settings. They show that several hundred of metres of evaporite can form in less than 128 kyr by evaporation of meteoric and seawater following a single marine flooding of the basin.

Valentin Rime

Haileyesus Negga

Robin Fentimen

Andres Rüggeberg

Afifé El Korh

Claudius Pirkenseer

Jean‐Charles Schaegis

Irka Hajdas

Thierry Adatte

Balemwal Atnafu

Tesfaye Kidane

Anneleen Foubert

Nature and significance of Late Pleistocene to Holocene thick evaporite deposits of the Danakil Depression, Afar, Ethiopia

晚更新世至全新世丹纳基尔洼地（埃塞俄比亚阿法尔地区）厚盐类沉积的自然特征与意义

作为该领域的国际领导者，SEDIMENTOLOGY 发表了跨越沉积学、沉积地质学和沉积地球化学的开创性研究。涵盖的领域包括：实验和理论谷物运输；沉积物通量；现代和古代沉积环境；层序地层沉积物-生物相互作用；古土壤；成岩作用；稳定同位素地球化学；环境沉积学

As a leading international journal in the field of sedimentology, Sedimentology publishes pioneering research that spans sedimentology, sedimentary geology, and sedimentary geochemistry. The covered areas include experimental and theoretical grain transport, sediment flux, modern and ancient sedimentary environments, sediment-biota interactions in sequence stratigraphy, paleosols, diagenesis, stable isotope geochemistry, and environmental sedimentology.

作为沉积学领域的国际领导者，Sedimentology 发表了跨越沉积学、沉积地质学和沉积地球化学的开创性研究。涵盖的领域包括实验和理论的颗粒运输、沉积物通量、现代和古代沉积环境、层序地层中的沉积物与生物相互作用、古土壤、成岩作用、稳定同位素地球化学以及环境沉积学。

Journals	Sedimentology
ISSN	0037-0746, 1365-3091
h-index	126
Journal Impact	2.69
Quartiles(Global)	GEOLOGY(Q1)
Quartiles(China)	地球科学(2区)地球科学地质学(1区)