Search

Fluvial networks are characterised by spatial and temporal transitions as geomorphic and ecological processes within these systems are mediated longitudinally by sediment and water fluxes which vary spatially in magnitude and variability. The aim of this special issue was to shed light on the nature of source-to-sink fluvial transitions associated with spatial and temporal variability in geomorphic and hydrological processes. We encouraged contributions that considered fluvial transitions at any spatial or temporal scale, and invited research that addressed the implications of such transitions. The number of submissions was limited, which was potentially indicative of the lack of field-based studies being conducted at a catchment- or source-to-sink scale. Two of the published submissions considered longitudinal transitions in sediment sources using a sediment finger-printing approach, while the remaining two articles combined traditional fluvial sedimentology techniques with optically stimulated luminescence chronology to deduce controls on river reach flood dynamics. As we enter a time of unprecedented human impact on the environment, there is a clear need for future research to focus on the catchment as a holistic unit as the interconnectedness of landscape pattern and process has implications for biodiversity, water quality, ecosystem service provision and thus catchment management. [ABSTRACT FROM AUTHOR]

Zones of alluviation at tributary – trunk confluences can act as sediment storage/transfer switches. Evaluating the temporal variation in tributary – trunk connectivity is key to understanding the origin, dynamics and residence time of tributary alluvial fill sequences, and determining relative and interacting effects of different drivers of landscape development. This paper evaluates processes and timescales of tributary (Prins River) – trunk (Touws River) connectivity at a site in the Little Karoo, as context for discussing sediment dispersal dynamics and implications for interpreting the landscape response to environmental change. An alluvial terrace in the tributary valley preserves a chronology (optically stimulated luminescence) of tributary valley alluviation that is regionally synchronous with valley alluviation in the upper Huis River and floodplain alluviation in the lower Touws and Groot rivers. A climatic shift within the Little Karoo at ~1000 years BP from relative aridity to relative humidity (and higher-energy rain-bearing circulation types) may have initiated widespread re-working of alluvial fills and the breaching of geomorphological buffers. Alternatively, there may be an intrinsic limit to sediment preservation potential associated with a regional floodplain cycling time of one to two thousand years. Longer archives are needed to contextualize fluvial responses to climatic variability in the region. [ABSTRACT FROM AUTHOR]

The White Hills Gravel is the coarsest fluvial gravel within Victoria, southeastern Australia, and outcrops discontinuously across a substantial part (>35 000 km2) of this region. It overlies a major regional unconformity representing >300 Ma, and is dominated by conglomerate (61% of beds), with less abundant sandy lithofacies (36% of beds) and rare mudstones (3% of beds). The sedimentary characteristics of the basal conglomerates (e.g. thick bedding, common boulders, very poor sorting and in places chaotic appearance) indicate deposition by significant paleofloods, including debris floods, within braided streams that had similar flow directions to the modern drainage. Paleohydraulic calculations estimate that the paleofloods had discharges exceeding >7200 m3 s−1, over 25 times the largest recorded floods in the same valleys. These paleofloods were probably caused by exceptionally severe storm systems, consisting of many individual thunderstorms. Deposition of the White Hills Gravel has previously been attributed to the mid-Cretaceous uplift that affected southeastern Australia, but the maximum possible age of the formation (early Paleocene) is too young for this to be a viable explanation. Instead, the White Hills Gravel may have been deposited during a period of increased precipitation at the Paleocene–Eocene Thermal Maximum (ca 56 Ma), when an intensification of the hydrological system generated significant sediment responses within fluvial systems around the world. Modelling indicates that this climatic event had a substantial impact in Victoria, where increases in mean annual precipitation (50–60%) and the most extreme rainfall rates achieved by the strongest storms (60–70%) were some of the largest globally, and frequent and intense Atmospheric Rivers were an important part of the hydrological system. These factors, together with a period of disturbed vegetation cover, resulted in major paleofloods that could have deposited the coarse-grained conglomerates of the White Hills Gravel. KEY POINTS: The White Hills Gravel in central Victoria is dominated by conglomerate (∼61% of beds), with lesser sandstone (∼36% of beds) and rare mudstone (∼3% of beds). In valleys across the central Victorian Highlands, White Hills Gravel outcrops are characteristically elevated above the Calivil Formation, and in the Campaspe and Loddon valleys, the long profiles of both formations cross over downstream. There is no evidence of a tectonic origin for the formation; instead, the White Hills Gravel was most likely deposited in response to a sharp rise in precipitation. The very-coarse-grained base of the formation was deposited by major thunderstorm-generated paleofloods with discharges up to and exceeding 7200 m3 s−1 in small catchments. The White Hills Gravel may denote a significant fluvial response to climate modification across the Paleocene–Eocene Thermal Maximum. [ABSTRACT FROM AUTHOR]

A toxodontid (Notoungulata) specimen (CHN-UNLC-P-V-4) is the first fossil from the Paso de las Carretas Formation that crops out in the Río Quinto Basin (Neogene), to the east of San Luis city (Argentina). The geological study provides a new stratigraphic section and the position of sediments in the valley depocentre permits inferring an older age than that of the Río Quinto Formation, which implies an early Late Miocene age for the Paso de las Carretas Formation. This age agrees with the identified cf. Ocnerotherium intermedium (taxonomic determination supported by a phylogenetic analysis), as this species was recognised in the Chasicoan Stage/Age of San Luis Province. CHN-UNLC-P-V-4 includes a mandibular fragment with ventral extension, preserving m1–3, a symphysis fragment with incisors, and the partial upper tooth series. A body mass of ~ 1700 kg is estimated. The mandible is similar to that of Dinotoxodon and Gyrinodon, but teeth (mainly upper ones) approach CHN-UNLC-P-V-4 to O. intermedium. As the mandibular extension of this species was not established, but likely present and lower teeth have some differences, we maintain an open nomenclature for CHN-UNLC-P-V-4. The similar incisors to the holotype of ‘Neoadinotherium triangulatum’ supports the latter might belong to O. intermedium, as previously suggested. [ABSTRACT FROM AUTHOR]

A series of well-exposed Paleogene sedimentary successions in the Kohat Basin of northwestern Pakistan (western Himalayas), are used to document the development of Paleogene sedimentary sequence deposited in a clastic–carbonate–evaporate distally steepened to a homoclinal ramp setting. Larger benthic foraminifer stratigraphy, sedimentology and microfacies were used to reconstruct the depth of deposition of the sediments and to aid in reconstructing the subsidence history of the sedimentary basin through the Paleogene. Based on the timing of the cessation of marine sedimentation and the subsidence analysis of the Paleogene rocks of the Kohat Basin, we conclude that a proto-closure of the basin occurred in the early Eocene (Ypresian) at ca 50–49.5 Ma, followed by return of marine sediments, with full closure of the Tethys seaway in the middle Eocene ca 40–41.2 Ma (Lutetian), potentially resulting in diachroneity of emergence of basins along strike of the orogen. Paleogene Larger Benthic Foraminferal biostratigrphy and facies information in the Eastern Tethys segment of the Kohat Basin, Pakistan are presented. Distally steepened-homoclinal ramp deposits were found. The proto-closure of Tethys occurred around 49.5 Ma with complete closure at 41.2–40 Ma due to India-Asia collision. [ABSTRACT FROM AUTHOR]

The Upper Miocene-Lower Pliocene Río Negro Formation (Río Negro Province, Argentina) contains diverse and abundant continental trace fossils. The purpose of this contribution is to recognize distinctive trace fossil assemblages in interdune lakes as response to lake expansion and contraction. The interdune deposits host 23 invertebrate, vertebrate, and plant ichnotaxa that are linked to the hydrological dynamics of the lake. During lake expansion a highly diverse subaqueous trace fossil assemblage reflects an infaunal bivalve population living in a littoral zone with swampy vegetation and semiaquatic mammals. The trace fossil assemblage recorded during Lake Highstand is less diverse and mostly linked to bivalve-generated trace fossils reflecting resting, locomotion, and escape/equilibrium behaviour (comparable to the Mermia ichnofacies). The assemblage during lake contraction exhibits high ichnodiversity and is dominated by vertebrate trace fossils reflecting foraging activities of shorebirds, cursorial birds, and herding semiaquatic mammals and ground sloths frequenting water holes. Flat sandy areas with moist substrates marginal to the interdune lake displayed a moderate ichnodiversity and its distinctive components were armadillo meniscate burrows and footprints in cross-section, as well as subvertical calcareous root casts. Neogene interdune lacustrine deposits reflect a particular zonation of trace fossils in response to changing physical conditions. [ABSTRACT FROM AUTHOR]

Informed by Māori oral histories that refer to past catastrophic marine inundations, multi-proxy analysis of stratigraphic records from Swamp Bay, Rangitoto ki te Tonga (D'Urville Island) shows evidence of an anomalous deposit extending some 160 m inland. The deposit includes two distinct lithofacies. The lower sand unit is inferred to have been transported from the marine environment, with corresponding increases in the percentages of benthic marine and brackish–marine diatoms, and geochemical properties indicative of sudden changes in environmental conditions. Radiocarbon dating indicates the deposit formation is less than 402 yrs BP, and pollen indicates it is unlikely to be younger than 1870 CE. Core stratigraphy age models and co-seismic chronologies point to the marine unit most likely being emplaced by tsunami transport associated with rupture of the Wairarapa Fault in 1855 CE. The overlying unit of gravel and silt is inferred to be fluvial deposit and slope-wash from the surrounding hills, loosened by ground-shaking following the earthquake. These findings indicate the 1855 CE earthquake may have been more complex than previously thought and, or, available tsunami modelling does not fully capture the local complexities in bathymetry and topography that can cause hazardous and localized tsunami amplification in embayments like Swamp Bay. [ABSTRACT FROM AUTHOR]

The Israelite Plain, a narrow terrace at the western edge of the Great Australian Bight, is characterised by a series of schizohaline, ephemeral lakes leeward of a marginal marine eolianite dune complex that has many similarities to the Coorong Coastal Plain (CCP). The late Pleistocene and Holocene sediments are a mixture of dominantly quartzose sand and lesser carbonate components. Paleolagoon to shallow marine MIS 5e, mollusc-rich quartzose deposits are capped by calcrete or karst and contain a biota similar to the well-documented, coeval Glanville Formation on the CCP. Holocene sands with minor carbonate are also lagoonal and resemble many modern Coorong Lagoon deposits. Both deposits are interpreted to reflect marine accumulation during sea-level highstands. Lakes today range from dry to water-filled with most floored by calcareous quartzose sand. Microbial influenced sedimentary structures in the form of pustular to laminated mats veneer lake margin bedrock and sediment. Carbonate minerals are mostly calcite with abundant accessory magnesium-calcite, aragonite and traces of magnesite, monohydrocalcite and halite. Gypsum is minor but ubiquitous and floors one of the smaller, marginal-marine lakes. Although having a similar evaporative climate and evidence of groundwater resurgence like Coorong lakes, there is no significant synsedimentary dolomite. This aspect is interpreted to reflect the narrow width of the plain, and the Mg-poor source of groundwater from the nearby karst Nullarbor Plain to the north. The Israelite Plain, together with other coeval, young successions marginal to the Southern Ocean under a semiarid climate now illustrate the depositional variations and early diagenetic differences that can occur in similar environments adjacent to a cool ocean. The Israelite Plain is a narrow, marginal marine terrace covered by Quaternary, lagoonal, eolian to lacustrine, calcareous siliciclastic sands, similar to several other calcareous terraces along the southern Australia coast. The interpreted sediment ages are late Pleistocene stage MIS 5e with the deposit sporadically overlain by similar Holocene deposits. Most 14C age dates are suspicious because of interpreted diagenesis or MIS 5e age, whereas U/Th age dates appear correct or altered by diagenesis. Pleistocene biota is dominated by the bivalve Anadara trapezia, whereas Holocene deposits contain a varied array of cooler water molluscs. The carbonates are similar to those on the Coorong Coastal Plain but do not contain any dolomite likely because of climate and lack of Mg-groundwater flow. [ABSTRACT FROM AUTHOR]

The complexity of the Kaikōura earthquake rupture and tsunami generation presented a unique opportunity to examine and learn from a modern event. This paper reviews how the five years of research following the Kaikōura tsunami have improved our understanding of the event and our knowledge of tsunami science across a range of disciplines. Teams of researchers and practitioners across disciplines of tsunami hazard modelling, palaeotsunami, risk and impact science, early warning, and emergency management learned from the event to calibrate models, enhance proxies for interpreting palaeotsunami deposits, and improve disaster risk readiness, reduction and response measures. While new scientific knowledge has been developed about the co-seismic hazard and risk facing Aotearoa-New Zealand, fundamental questions nonetheless remain about tsunami-generating sources and the likely return period for high impact events in Aotearoa-New Zealand. Further scientific endeavour is needed to investigate the onshore and offshore geological records to help improve understanding of tsunami hazard and history to underpin risk and impact assessments informing more effective disaster risk management. Lessons also emphasise a need for more effective partnership, participation, education, and engagement to increase local community capacity and capability to respond to local source tsunami events. [ABSTRACT FROM AUTHOR]

Cenozoic sediments cover much of Queensland's landscape and record changes in climate and flora that evolved in tandem with the tectonic evolution in eastern Australia, associated with uplift and erosion events arising from Late Cretaceous sea-floor spreading in the Coral Sea, leading to the passive margin we see today. In eastern Australia, incised and potentially fault-bounded valleys developed on the pre-Cenozoic landscape and were variably infilled at different times by siliciclastic sediments, carbonaceous muds and peat, and basaltic lava flows. This study examines a 100 m-deep drill core through one such siliciclastic-dominated paleochannel incised into upper Permian coal measures on the western limb of the Bowen Basin. Palynological analysis, core logging, hyperspectral logging of the core, X-ray diffraction (XRD), SEM–EDS and U–Pb zircon geochronology were used to investigate the age and origins of these clay-rich deposits. Palynological analysis confirmed that the strata belong to the upper Paleogene and Neogene Suttor Formation, a time when Australia's climate has been interpreted to shift from wet and warm to a more arid setting. Core logging revealed that the sequence in the studied channel began as a breccia/alluvial fan with chaotic angular clasts of Permian laminated siltstone, tuff and coal floating in disturbed poorly lithified sand with evidence of soft sediment deformation, possibly initiated by localised faulting. These clasts were continually reworked and broken down into a clast supported pebble conglomerate capped by a series of claystone with intermittent carbonaceous claystone and lignite, interpreted to have formed in a lacustrine environment that could be localised on the floodplain (oxbow) or more regional in extent. Above this, and interpreted from palynology as corresponding to a climatic shift to more arid conditions, are well sorted but subrounded sugar sands and intermittent clays with abundant iron staining (?paleosols) interpreted to represent sandy ephemeral channels. These are overlain by extremely weathered undated basalts. The hyperspectral logging of the core and XRD studies of the white claystone samples indicate that they are kaolinite-rich, but observations under SEM–EDS noted that their honeycomb structure mimicked that of smectite. The presence of abundant zircon suggested the possibility of syndepositional volcaniclastics, but U–Pb zircon geochronology recorded an age of 272–254 Ma (middle to late Permian). Hence local recycling of the tuffaceous smectite-rich coal measures within the incised alluvial system, assisted by intense weathering under a warm and wet climate, and potentially acid leaching from the organic-rich layers was the origin of the kaolinite-rich clay strata. Clay-rich Cenozoic paleochannels in the northern Bowen Basin belong to the upper Paleogene and Neogene Suttor Formation, based on palynological study. The clay-rich strata are developed by local recycling of middle to late Permian tuffaceous smectite-rich coal measures. The interpretation based on palynology and clay mineralogy confirm that Australia experienced a shift from wet and warm to a more arid climate during the upper Paleogene and Neogene. [ABSTRACT FROM AUTHOR]

Environmental studies based on analyses of fluvio-aeolian successions with paleosols in central Poland, forming the central part of the European Sand Belt, are presented. Paleogeographic reconstruction was based on high-resolution analyses of four sites using sedimentological and paleopedological methods as well as forty-four optically stimulated luminescence and fourteen radiocarbon dating measurements. Age-identified individual lithological and soil units were first correlated between sites, emphasizing the differences between them. The results were then correlated with Greenland ice-core stratigraphic units reflecting global environmental changes in the Late Pleniglacial and Lateglacial interstadial, thus ranging from GS-2.1a, through the GI-1 complex (seven subunits), to GS-1. Studies revealed considerable sensitivity of fluvio-aeolian succession to climate changes and oscillations. Climate ameliorations are recorded in fossil soil horizons developed beneath different types of vegetation cover. We detected that the climate cooling GI-1d (the Older Dryas) was not the main phase of dune formation as had been claimed earlier. It is postulated that dunes in the extraglacial zone were formed mainly in GI-1c2 (the Early Allerød). Preexisting dunes were transformed in GS-1 (the Younger Dryas) and in the Early Holocene, locally interrupted by soil formation. [ABSTRACT FROM AUTHOR]

Identified as one of the most vulnerable environment to the impacts of sea-level rise, the morphological and hydrological diversity of coastal areas complicates their study. To understand their evolution, it is essential to characterize their current morpho-sedimentary distributions and processes. Morphologic interpretation, from LiDAR data, coupled with grain-size and geochemical analyses of 200 samples, subsequently interpreted with statistical tools (PCA), allow us to determine the pattern of sedimentary transport of Saire Bay (Normandy, France).Even if the area is mainly dominated by tidal currents, the original morphology of Saire Bay highlights an uncommon complex circulation on a sandy tidal flat. Sedimentary land-sea exchanges, induced by tidal current, do not occur through the river Saire network in the north, but in south, along a less apparent secondary channel. Results provide an essential base to better understand the evolution of the coastline. [ABSTRACT FROM AUTHOR]

The extent of the Southern Alps icefield in New Zealand is well-constrained chronologically for the last glacial cycle. The sediment-landform imprint of this glacial system, however, offers insight into ice-marginal processes that chronological control cannot. We present the first detailed investigation of sediments along the southwestern shores of Lake Tekapo, South Island. We identify seven lithofacies, from which a five-stage palaeoglaciological reconstruction of depositional and glaciotectonic events is proposed: (i) ice-marginal advance and deposition of outwash gravels in lithofacies (LF) 1; (ii) ice-marginal recession and the development of an ice-contact lake, manifest in rhythmite deposition and iceberg rafting of dropstones (LF 2), followed by a depositional hiatus; (iii) ice-marginal recession recorded in ice-proximal aggradation of glaciofluvial hyperconcentrated flows (LFs 3, 4); (iv) ice-marginal advance documented by glaciotectonic disturbance and localized hydrofracturing, coeval with the deposition of delta foresets and a subglacial diamicton/till (LFs 5, 6); (v) final stages of ice-marginal recession and deposition of outwash gravels in LF 7. Two infrared stimulated luminescence ages were obtained from the glaciolacustrine sediments and, whilst the dating has some limitations, the sediments pre-date both the global and local Last Glacial Maximum. Overall, this sequence, consistent with sediment fills recorded elsewhere across South Island, suggests recurrence of processes from different glacial advances and the role of topographic constraints on maintaining lake positions. [ABSTRACT FROM AUTHOR]

During Neoproterozoic global climate changed drastically and associated glacial deposits have been found worldwide. However, there are few such records at the southern margin of the North China Craton (NCC), limiting the comparison of the glacial deposits with other parts of the world. In this study, five sections of the Neoproterozoic Luoquan Formation were investigated in a systematic field survey using traditional sedimentology, geochemistry, and geochronology methods to reveal genesis, paleoclimate, paleoenvironment, and provenance of the Luoquan Formation. The results reveal depositional evidence for glaciation, such as sedimentary characteristics of massive diamictites, bedded and weakly bedded diamictites, sandstone lenses, lonestone-bearing siltstone, glacial relics, and striated pavements. All geochemical indicators show positive trends, such as in the values of Fe/Mn, Mg/Ga, Sr/Ba, ΣREE, and Cu/Zn. The zircon U–Pb data of the stable sandstone strata in the Luoquan Formation show a main peak at 2494 million years (Ma) and secondary peaks at 1656, 2100, and 2233 Ma. Sedimentary characteristics, glacial relics, changes in geochemical values, and the provenance age of detrital zircons suggest that the Luoquan Formation represents glacial meltwater deposits that eroded the nearby strata in a gradually warming environment. The direction of glacier migration, from north to south, revealed that the NCC deposition process occurred in the late Neoproterozoic. [ABSTRACT FROM AUTHOR]

The Coniacian non-marine portion of the Frontier Formation in southwestern Montana has been primarily studied stratigraphically, whereas its trace fossil record and relative sedimentological significance have remained overlooked so far. We present the first description of a trace fossil assemblage reported from Frontier Formation deposits exposed in the western Centennial Mountains, Beaverhead County, Montana. Three main lithofacies groups with distinctive trace fossil assemblages have been recognised at the locality of Price Creek: (1) coarse-grained, thin and laterally extensive cross-bedded sandstone channel bodies characterised by rare vertical, passively filled burrows; (2) fine-grained overbank sandstones and siltstones, with abundant horizontal, meniscated, and unwalled burrows, sinusoidal trails, vertical burrows, and dinosaur tracks, and (3) fining-upward, planar cross-bedded silty sandstones, associated with carbonaceous plant material and bone fragments. The trace fossil assemblage is ascribed to the pre-desiccation suit of the Scoyenia ichnofacies. The occurrence of theropod, ornithopod, and thyreophoran dinosaur tracks, and invertebrate trace fossils suggests considerable diversity of terrestrial and aquatic fauna. Tracks described here represent the first dinosaurian record reported from Coniacian deposits in Montana and one of the few fossil records reported from non-marine Coniacian deposits in North America. [ABSTRACT FROM AUTHOR]

A reconstruction of the last 2,000 years BP of environmental and oceanographic changes on the western margin of Spitsbergen was performed using a multidisciplinary approach including the fossil assemblages of diatoms, planktic and benthic foraminifera and calcareous nannofossils and the use of geochemistry (X-ray fluorescence spectroscopy, X-ray diffraction). We identified two warm periods (2,000-1,600 years BP and 1,300-700 years BP) that were associated with the Roman Warm Period and the Medieval Warm Period that alternate with colder oceanic conditions and sea ice coverage occurred during the Dark Ages (1,600-1,300 years BP) and the beginning of the Little Ice Age. During the Medieval Warm Period the occurrence of ice-rafted debris and Aulocoseira spp., a specific diatom genus commonly associated with continental freshwater, suggests significant runoff of meltwaters from local glaciers. [ABSTRACT FROM AUTHOR]

Google Earth Engine is used to trace the spatial distribution of the lacustrine coastal megaclast deposits (LCMDs) of the Lake Malawi. Wide distribution of LCMDs is established, and they are especially common on the northeastern and southern coasts. The studied deposits can be subdivided provisionally into lenticular, patchy, and point-scale categories. Apparently, the spatial distribution of these deposits around the Lake Malawi is controlled by the regional geology and topography. This case study proves the efficacy of the virtual journeys for quick finding and mapping LCMDs along lake coasts, although not for their quantitative analysis and in-depth descriptions. [ABSTRACT FROM AUTHOR]

A palynological study of 239 outcrop samples and their sedimentological context was undertaken on the Pliocene Productive Series in the Kirmaky and Yasamal valleys, eastern Azerbaijan. The Productive Series is primarily a representation of the palaeo-Volga and forms the main hydrocarbon-producing reservoirs in the South Caspian Basin. Most sands are interpreted as fluvial, based on sedimentary characteristics. Mudstone and siltstones often contain freshwater and brackish assemblages interpreted as 'Caspian lake' transgressions, indicative of rapid Caspian Sea level change during the Pliocene. Most samples contain rich assemblages including pollen, spores, dinoflagellate cysts, algae and fungal bodies. Common tree pollen elements include Pinus, Alnus, Betula, Carya, Juglans, Pterocarya, Quercus and Ulmus, which all occur in present-day vegetation or pollen records from the Caucasus or Urals. Herbaceous pollen includes Amaranthaceae, Asteraceae (including Artemisia), Ephedra and Poaceae, commonly found in the drier Caspian regions. The dinoflagellate cysts include 'Peri-paratethyan endemic' taxa such as Caspidinium rugosum and Spiniferites cruciformis. 'Pannonian' species such as Thalassiphora balcanica, Romanodinium areolatum and Spiniferites oblongus confirm the persistence of these taxa into the early Pliocene in Eastern Paratethys, around five million years later than their first documented presence in Central Paratethys. 'Caspian lake' influences diminish up-section, as indicated by a progression from brackish to freshwater and sub-aerial conditions. Productive Series deposition was mainly driven by the combined effects of lake level and catchment climate. The principal hydrocarbon reservoir sands were deposited as a result of increased catchment humidity, whereas drying conditions led to reduced coarse clastic input and deposition of alluvial plain mudstones. Productive Series deposition terminated with the onset of the marine-influenced Akchagyl Series, which spans the Plio-Pleistocene boundary. The lowermost sediments of the Akchagyl Series are freshwater in origin and grade up-section into marine beds containing dinoflagellate cysts of Arctic affinity. [ABSTRACT FROM AUTHOR]

Sedimentary successions and igneous rocks exposed in Eastern Sayan provide an important geological record on the tectonic evolution of the southwestern margin of the Siberian Craton during the Neoproterozoic. Here we present sedimentological and detrital zircon provenance data from key stratigraphic units, complemented by a new U-Pb zircon age of 718 ± 6 Ma from the mafic Nersa magmatic complex. Sedimentological and provenance data from the lower part of the stratigraphic succession (Karagasy Group) show that these rocks were deposited in a passive margin setting after 750 Ma and before the emplacement of the Nersa magmatic complex. The upper part of the stratigraphic succession (Oselok Group) consists of Cryogenian and Ediacaran glaciogenic deposits and associated cap carbonates, overlain by mid to late Ediacaran sequences of dominantly shallow-marine and fluvial siliciclastic rocks. Provenance data indicate that rocks from the Tuva-Mongolia and Zavkhan terranes provided a significant input of detrital material into the sedimentary basin that was the source of the glacial deposits. Orogenic processes during the late Ediacaran (ca 570–540 Ma) in Eastern Sayan were likely associated with the accretion of the Tuva-Mongolia terrane, as indicated by the detrital zircon data. [ABSTRACT FROM AUTHOR]

This article presents the results of a marine geophysical and sedimentological study carried out around Lesvos Island (NE Aegean) to investigate the potential of exploitable marine aggregate (MA) deposits that could be used for beach replenishment purposes. Sub-bottom profiler data showed a good prospect for potential coarse-grained deposits in two of the three surveyed areas around Lesvos. Grain size and mineralogical analysis of the surficial sediments revealed sands that could properly feed nourishment schemes for eroded beaches or artificial beach development. Observed MA volumes are considered adequate for renourishment operations, when the threat of projected sea-level rise is introduced. Environmental constraints, as well as human activities, are considered for the suggestion and prioritization of specific areas for detailed surveying before future exploitation. [ABSTRACT FROM AUTHOR]

The genesis of dolomite is a century-old mystery in sedimentology. The 'microbial dolomite model' proposed in recent years provides new insight into the study of dolomite genesis. However, the lack of research on the precipitation rate makes it difficult to judge whether the microbial dolomite can be deposited as a thick dolomite formation alone. In this review, the precipitation rates (about 10−12 to 10−9 cm · s−1) and productivity (about 1.3–7.9 × 10−7 cm · s−1) are estimated preliminarily, the results of cold seeps (10 −11.7 to 10 −12.5 cm · s−1) and previous modeling work (10−11.8 cm · s−1) were collected, and the possible precipitation rates of ancient (6.1–7.5 × 10−11 cm · s−1) and modern sabkha (5.9 × 10−10 to 1.3 × 10−9 cm · s−1) were calculated. To some extent, it does be possible that microbial dolomite can form a thick layer alone (because of the high productivity), but increasing order is a long process with the transformation of diagenesis. In terms of precipitation rate, there is less possibility in Sabkha, but more in cold seeps. The study on the precipitation rate of microbial dolomite may bring new enlightenment to the dolomite genesis and other fields, such as the reconstruction of paleoenvironment and study of the origin of life, but more elaborate culture experiments and modeling works are needed. [ABSTRACT FROM AUTHOR]

Over the night of 11–12th August 2020, unusually intense convective rainfall triggered several debris flows along the Lomond Hills escarpment. Rainfall intensities locally exceeded an estimated 0.33% annual exceedance probability. Each debris flow had a different magnitude and physical character depending on the availability of water and sediment and the effectiveness of the vegetation buffer, such that similar-looking micro-catchments responded in different ways. The largest debris flow far exceeded the others in magnitude, extending over 1 km with a descent of 246 m and an estimated volume of c. 1500–3000 m3, causing damage to a forestry road. Debris was entrained from a gullied relict talus, including fallen trees and incision of Lateglacial glaciofluvial sand. Deposit sedimentology and morphology demonstrate an initial debris-flow surge probably happened early in the storm coinciding with the greatest runoff generation, followed by later fluvial incision and sediment reworking. This appears to be the largest such event in the Lomond Hills for more than 90 years and may be characteristic of the landscape response to projected increases in convective rainfall intensities in twenty-first century summers. [ABSTRACT FROM AUTHOR]

The lower to ?middle Cambrian rocks (Terreneuvian, Series 2 and possibly Miaolingian) of the Arrowie Basin are exposed superbly in the Flinders Ranges of South Australia. They comprise two major sedimentary packages: a lower carbonate-rich succession (Hawker Group and correlates) and an upper siliciclastic-dominated succession (Billy Creek Formation, Wirrealpa Limestone and Lake Frome Group). These rocks form one of the most complete lower Cambrian (Terreneuvian and Series 2) successions globally. They contain one of the most diverse known early Cambrian biotas in the world, with trilobites, archaeocyaths, bradoriides, brachiopods, some of the earliest known coralomorphs, small shelly fossils, molluscs, hyoliths, acritarchs and trace fossils. Series divisions, based on ranges of shelly fossils and archaeocyath biostratigraphy are currently being established. Ancient reef structures are prominent in several areas. Syndepositional faulting and diapiric activity affected sedimentation in places. The global significance of the region is enhanced by the presence of tuff horizons at some levels, which provide the opportunity to link the biostratigraphic zones with radiometric dates and carbon isotope curves. [ABSTRACT FROM AUTHOR]

We present the results of a sedimentological and mineralogical study conducted on 305 marine sediment samples (32 seafloor grab samples and 273 subsea floor samples from 91 vibrocores) collected in the marine area of the eastern Pozzuoli Bay, offshore the area of Bagnoli, that has been the site of heavy industrial activity for more than a century. The coastal (onland-offshore) area of Bagnoli–Coroglio has been recognised as a contaminated Site of National Interest (SNI) by the Italian Ministry of the Environment (2000–2001) and since then it has been the subject of a series of environmental studies that have documented a severe contamination of soils onland and marine sediments offshore. Based on the outcomes of the sedimentological classification discussed in this study we have constructed a series of thematic maps illustrating the areal distribution of the sedimentary facies at different stratigraphic levels. Our interpretation provides a support in reconstructing the complex set of environmental changes that have affected the offshore of the eastern Pozzuoli Bay prior to and after the termination of the industrial activity of the Bagnoli brownfield. [ABSTRACT FROM AUTHOR]

Upper Triassic sandstones from Mendeleev Rise were analyzed and compared to turbiditic sandstones of the same age from Wrangel Island and Chukotka, Arctic Sea region. Medium-grained lithic arenites dominate all of these. The quartz content is higher in the sandstones from Mendeleev Rise than in those from Wrangel Island and Chukotka. Abundant quartz grains with microfractures and kaolinized feldspar are characteristic of the samples from Mendeleev Rise, whereas such features are lacking in the other areas. Quartz with microfractures is less abundant in Triassic turbidite sandstones of Chukotka and Wrangel and kaolinized feldspar is not present. Upper Triassic sandstones of Mendeleev Rise are characterized by a high Chemical Index of Alteration indicating intensive weathering in the source province. All sandstones have Th/Sc ratios ≤1. The chemical composition of sandstones suggests a quartzose sedimentary province for sandstones of Mendeleev Rise, an intermediate igneous province for Wrangel Island sandstones, and a mafic igneous provenance for Chukotka sandstones. Detrital zircon populations are similar in all Upper Triassic sandstones samples with a dominance of Paleozoic zircon. Facies studies of Triassic deposits in the Eastern Arctic of Russia indicate that sandstones from Mendeleev Rise were located near a continent and formed in a shallow or coastal-marine setting. Triassic deposits of Wrangel Island and Chukotka were deposited in a deeper marine environment. [ABSTRACT FROM AUTHOR]

Integrated ichnology, sedimentology and sequence stratigraphy of the Lower Quartzite Member to the Arkosic Sandstone Member of the Koti Dhaman Formation (Cambrian Series 2, Stage 4), Tal Group, Nigali Dhar Syncline, Lesser Himalayan lithotectonic zone are presented. Trilobite traces of Gondwanan affinity i.e., Cruziana salomonis, Cruziana fasciculata, Rusophycus dispar and Rusophycus burjensis are recorded along with Arenicolites isp. and Skolithos isp. from the Lower Quartzite Member. A rich and diverse ichnoassemblage attributed to the Cruziana ichnofacies is described for the first time from the Arkosic Sandstone Member of the same formation. Seven ichnofossil assemblages, i.e., Cruziana-Rusophycus, Planolites-Palaeophycus, Cruziana problematica, Diplichnites, Cochlichnus anguineus, Bergaueria perata and Psammichnites gigas have been recognized in the Lower Quartzite to Arkosic Sandstone members of the Koti Dhaman Formation. Seven sedimentary facies i.e., sandstone–shale facies (FT1), cross-bedded (trough and planar) sandstone (FT2), bedded sandstone facies (FT3), shale facies (FT4), shale–sandstone facies (FT5), shale-rippled sandstone facies (FT6) and planar and trough cross-laminated sandstone (FT7) and four facies associations FA1-FA4 are identified in the Koti Dhaman Formation. The formation contains shallowing upward parasequences of a tidal flat complex. Overall, two major events are recognized: i) the break in sedimentation between the Lower Quartzite Member and the overlying Shale Member probably related to forced-regressive event and ii) the facies shift from FT6 to FT7 of the Arkosic Sandstone Member represents an erosive transgressive event; the surface is interpreted as wave ravinement surface, which also serves as a sequence boundary. Integrated ichnology, sedimentology and sequence stratigraphic studies indicate that the Lower Quartzite Member was deposited in a shallow subtidal sand sheet complex and tidal flat complex; the Shale Member was deposited in a mud flat setting of a tidal flat complex, and the Arkosic Sandstone Member in a mixed-flat (tidal flat complex) to sand sheet complex front and margin (subtidal sand sheet complex). Overall, the lower to middle part of the Koti Dhaman Formation represents a tide-dominated shallow subtidal–intertidal to mud-flat subenvironments of the tidal flat complex. A palaeogeographic reconstruction of lower Cambrian (516–514 Ma) is presented based on the distribution of trilobite traces from the Lesser Himalaya and the Bikaner–Nagaur area of Peninsular India (eastern Gondwana), Egypt, Jordan, Turkey (western Gondwana) and Canada (Avalonia). [ABSTRACT FROM AUTHOR]

Organic-rich black shales from the Upper Yangtze Platform from the Upper Ordovician and lower Silurian are considered excellent source rocks and unconventional reservoirs of hydrocarbons in South China. This research combined geochemical analyses and detailed sedimentological observations to investigate the depositional controls on organic-matter abundance in the prolific black mudstone of the Wufeng Formation and Long-1 Member of the lower Silurian Longmaxi. Six primary lithofacies deposited at variable marine water depths and under different water column chemistries were identified from a ∼50 m-long profile based on microscopic observations of sediment texture and structure, and analyses of total organic carbon (TOC) content, major and trace-element abundances, and pyrite framboid size. Our results showed that TOC content is strongly correlated with terrigenous SiO2 content and the non-detrital components of V, U and Mo, suggesting that the accumulation of organic matter in the studied shale was controlled by terrigenous clast fluxes and anoxic water conditions. However, the weak covariance relationship between TOC content and productivity proxies, including P/Ti and Ba/Al, demonstrates that the accumulation of organic matter was not controlled by primary productivity. The three high-productivity lithofacies of the Wufeng Formation and Long-1 Member have low Co*Mn values, indicating active marine upwelling during sedimentary periods. The northern margin of the Upper Yangtze Platform was an open basin system influenced by the Kwangsian Orogeny and global sea-level changes, but oxygen-depleted bottom waters in the basin favoured the accumulation and preservation of sedimentary organic matter, resulting in the formation of organic-rich black shales. [ABSTRACT FROM AUTHOR]

Because of its size and geographical position, the Cherbourg roadstead appears as a favourable site for Marine Renewable Energy (MRE) industry. As a result, Cherbourg harbour has undergone profound changes (2015 and 2016) due to the installation of industrial infrastructures to service the needs of expanding MRE further offshore. However, little is known about the morpho-sedimentary distribution and associated dynamics of seabed sediments before and after harbour transformations. This study focuses on sedimentary dynamics using detailed morphological and sedimentological analyses based on data acquired before changes (2012). The main map includes a unique bathymetric map (1:35,000) and sedimentary maps showing the percentage of the characteristic grain size fractions of 184 seabed samples. Despite the high tidal conditions, the roadstead construction had a significant impact on the sedimentary facies and distribution. This study provides a basis for future investigations on geomorphological evolution linked to the impact of anthropogenic development. [ABSTRACT FROM AUTHOR]

This paper presents an innovative multi-thematic map (1:2500) that integrates morpho-sedimentological data, hydrodynamic processes, seasonal morphodynamic transitions and the distribution of the benthic habitat of a Mediterranean microtidal, wave-dominated gravel beach system. It is part of a larger cartography of coastal areas, and is based on an interdisciplinary sea-land approach that is applicable worldwide and aims to facilitate coastal management practices and future scientific research. The applications to coastal management include: the facilitation of coastal vulnerability assessments; easy-to-access, up-to-date digital geospatial data; and baseline studies for the future assessment and monitoring of environmental changes. The main environmental features that control the marine processes of this gravel beach appear to be linked to geological and morphological contexts such as the presence of the river mouth, the outcropping of a beach-rock along the coastline, the deposition of gravelly sediment in the beachface and the seagrass cover. [ABSTRACT FROM AUTHOR]

Globally significant geoheritage features of the Cliefden Caves area, in the Belubula River Valley between Orange and Cowra in central western New South Wales, comprise a richly fossiliferous shallow-water limestone succession of Late Ordovician age (the Cliefden Caves Limestone Subgroup) overlain by deep-water laminites and allochthonous limestones of the Upper Ordovician Malongulli Formation. Key features of the Ordovician geology of the Cliefden Caves area that have been identified using the Geoheritage Toolkit as being of international significance are the abundance of unique and exceptionally diverse fossils in the Fossil Hill Limestone (forming the lower part of the Cliefden Caves Limestone Subgroup), which supplement detailed interpretation of carbonate-dominated deposition within an Ordovician volcanic island setting. The fossiliferous limestones preserve biostromes and local small bioherms of stromatoporoids and corals, and recurrent in situ and disarticulated/imbricated Eodinobolus shell beds formed in shallow, quiet-water, dominantly muddy carbonate sediments that passed up-sequence to clay-free carbonate environments. These mud-dominated carbonate sediments are interspersed with higher-energy conditions, represented by skeletal, lithoclastic and calcrete-ooid grainstones overlying disconformities, leading to the identification of subaerial disconformities and associated diagenesis in the Fossil Hill Limestone. The Fossil Hill Limestone is succeeded by massive limestones in the middle part of the Cliefden Caves Limestone Subgroup and then, in turn by the Vandon Limestone and the deeper-water graptolitic laminites of the Malongulli Formation—this completes a succession that is rarely preserved in the geological record, further enhancing the geoheritage significance of the Cliefden Caves area. [ABSTRACT FROM AUTHOR]

Shallow-marine to fluvio-estuarine deposits in Pohangina Valley represent an underexplored portion of the Whanganui Basin, a globally significant archive of Quaternary climate change. To address this, we document environments of deposition through facies analysis, tephrostratigraphy and biostratigraphy. The marine shelf environment is characterised by fossiliferous mudstone containing marine Mollusca. Estuarine facies consist of pumiceous sandstone, tephra, lignite and carbonaceous mudstone. Volcaniclastic and tephra-fall deposits record seven eruptions from the Taupo Volcanic Zone between c. 1.6 and 0.9 Ma. We identify and define Awahou Tephra (new) (c. 1.03 Ma), through mapping and geochemical analysis of constituent glass shards. Progressive retreat of the sea (c. 1.6 Ma) is indicated by a change from shallow-marine to fluvio-estuarine sedimentation. An east–west drainage system developed (c. 1 Ma), including ponding near Woodville from which an early ancestor of the Manawatu River exited, establishing an antecedent path to the Tasman Sea across the uplifting paleo-axial range. [ABSTRACT FROM AUTHOR]

A new vertebrate ichnological assemblage is described from the Hettangian Dolomitic Formation of the Causses Basin, at Le Serre (Lozère, southern France). We report tracks that complement the poor fossil record of lowermost Jurassic crocodylomorphs in Europe. Tetradactyl pes and pentadactyl manus imprints form a unique trackway. Traces are ascribed to Batrachopus isp. and they represent the third occurrence of this ichnogenus in European Hettangian geological formations. This is the first report of Batrachopus in Hettangian deposits of the Causses Basin. The tracks share some similarities with Batrachopus deweyi previously described from the Sinemurian of the Causses Basin. Crocodylomorph tracks co-occur with tridactyl dinosaur traces assigned to Dilophosauripus williamsi and Grallator isp. The sedimentology and palaeoichnology of the tracksite indicate that the depositional environment was a tidal to supratidal flat marsh that was emerged periodically. The ichnological assemblage from Le Serre and a synthesis of ichnotaxa co-occurring with Batrachopus in the European lowermost Jurassic tracksites confirm that crocodylomorphs living in marginal-littoral palaeoenvironments were part of theropod-dominated faunas, together with ornithopods but apparently without sauropods. [ABSTRACT FROM AUTHOR]

The hydrosedimentological monitoring with reliable data of suspended sediment concentration can be problematic when conventional methods are employed because these methods usually show measurements with stations and frequencies lower than desirable, therefore limiting the studies and the management of water resources. In this context, this paper shows a study carried out in the Mogi-Guaçu reservoir (São Paulo, Brazil) in which the correlation of data from sediment in suspension concentration was made, measured with automatic device (LISST-100X) and conventional sampling. By linear regressions and statistical tests, the efficiency of laser diffraction technique was assessed, and the concentrations of suspended sediments were estimated, for both of the performed campaigns. Through the statistical analysis of the results, it was possible to confirm that among all scenarios of linear regressions adopted, the model that divides the reservoir in sectors shows better concentration estimates, inferring that the concentration of suspended sediment has a characteristic behaviour of the segment of the Mogi-Guaçu reservoir. Therefore, the LISST-100X herein proved to be feasible for the case study. It should be noted that the use of this probe made it possible to obtain more data than those obtained using conventional techniques, enabling a more complete analysis of the reservoir and significantly reducing the work in the field, laboratory and office. [ABSTRACT FROM AUTHOR]

This paper illustrates a detailed geomorphological map (scale 1:50,000) of the marine and transitional terraces (glacio-lacustrine to marine) and raised shorelines linked to Holocene glacio-eustasy and neo-tectonics in the northern area of the Brunswick Penìnsula (Chilean region of the Strait of Magellan). The mapped area is located in Tierra del Fuego between the Segunda Angostura and Seno Otway. This map is the result of geomorphological field survey data integrated with the interpretation of aerial photographs and remote sensing imagery. The survey has allowed the mapping of a sequence of terraces and raised shorelines to be completed. The sequence mainly consists of four orders of marine and glacio-lacustrine terraced deposits, with elevations ranging from 25 to 1 m above mean sea level. The map also presents other landforms and deposits, with their formation linked to littoral, fluvial, glacial and aeolian processes. [ABSTRACT FROM AUTHOR]

The third-order sequences of the Yanchang Formation in the Ordos Basin were determined by a comprehensive analysis of surface outcrops, core, logging and seismic data. Natural gamma curves were studied by the band-pass method. The hidden stratigraphic sequence and six lithological cycles were extracted. By examining sequence boundaries and lithological cycles, we identified six third-order (including SQ1, SQ2, SQ3, SQ4, SQ5 and SQ6) and three second-order sequences in the Yanchang Formation. The sequence stratigraphy of the Ordos Basin was found to have the following special development characteristics: (1) the third-order sequence growths were totally stable, and the thickness of the Ordos Basin was relatively stable; (2) thick sand bodies did not form in lowstand systems because of underdeveloped slope breaks; (3) the third-order sequences had diverse features at different sedimentary periods; (4) the distribution of the depositional systems had various characteristics in different tectonic belts, and the entire sequence had the filling characteristics of multiprovenances and multicycles. The low-accommodation Ordos Basin in the Upper Triassic was limited by slow subsidence, gentle basement paleorelief, stable tectonic settings and sufficient sediment supply. The characteristics of the basin included stable developed sequences, limited preserved lowstand systems tracts, multiple depocentres and subsiding centres, development of many delta systems in the north and south of the basin controlled by the gradient of the basement paleorelief, and laterally stretching sediments. Results further indicated that the controlling factors of the third-order stratigraphic sequences of Yanchang Formation in the low-accommodation lacustrine Ordos Basin included sediment supply (provenance), climate and lake-level fluctuation. Overall, our case study indicated that the development characteristics and controlling factors of sequence stratigraphy in a low-accommodation lake basin provided a comprehensive method of establishing the sequence stratigraphic framework of a low-accommodation non-marine basin. Our results also predicted that the SQ3, SQ4 and SQ5 of the Qiaochuan and Zhidan areas favoured oil and gas prospecting of the Yanchang Formation. [ABSTRACT FROM AUTHOR]

The paper describes the training, validation, testing, and application of models of artificial neural networks (ANN) for computing the cross-shore beach profile of the sand beaches of the province of Valencia (Spain). Sixty ANN models were generated by modifying both the input variables as the number of neurons in the hidden layer. The input variables consist of wave data and sedimentological data. To select and evaluate the performance of the optimal model, the following parameters were used: R2, absolute error, mean absolute percentage error, and percentage relative error. Finally, the results are compared with the numerical model proposed by Aragonés et al. (2016b) for the equilibrium profile in the study area. The results show a mean absolute error of 0.21 m compared to 0.33 m Aragones’ model, significantly improving the results of the numerical model in the bar area around de Valencia Port. In addition, when comparing the results with other methods currently used (Dean’s or Vellinga formulation), the errors of these compared to ANN are of the order of 167 and 1538% higher, respectively. [ABSTRACT FROM AUTHOR]

The study of glacial landforms is important for understanding past subglacial processes and dynamics. The Nordenskiöldbreen forefield hosts numerous streamlined landforms resulting from a late Holocene glacier advance. Here, we present a geomorphological map constructed from remotely sensed imagery of both the marine and terrestrial environments. Sixteen drumlin bedforms have been identified in the mapped forefield - ten terrestrial and six submarine. A sedimentological investigation of drumlins in the Nordenskiöldbreen forefield shows that they are composed of pre-existing sediments draped by a thin layer of till which formed during the most recent advance of the glacier. Analysis of recent (2008-2012), high-resolution aerial imagery of all the glacier forelands in Svalbard suggests drumlin features are widespread. Here, we have identified 49 previously undocumented terrestrial glacier forefields, where subglacially streamlined landforms occur within the margins of the late Holocene glacier extent. Additionally, the location of 53 previously published submarine sites with streamlined landscape have been mapped. Thirty of these are sites with streamlines of late Holocene origin and 18 with Last Glacial Maximum (LGM) origin. Based on our detailed case study at the Nordenskiöldbreen forefield, and remote sensing survey, we suggest that drumlins in Svalbard form predominantly in forefields of glaciers with low-elevation termini, in areas with abundant fine-grained sediments, and where the glaciers are able to advance into an area of unconstrained topography. [ABSTRACT FROM AUTHOR]

On the basis of detailed sedimentological investigation, three types of hybrid event beds (HEBs) together with debrites and turbidites were distinguished in the Lower Cretaceous sedimentary sequence on the Lingshan Island in the Yellow Sea, China. HEB 1, with a total thickness of 63-80 cm and internal bipartite structures, is characterised by a basal massive sandstone sharply overlain by a muddy sandstone interval. It is interpreted to have been formed by particle rearrangement at the base of cohesive debris flows. HEB 2, with a total thickness of 10-71 cm and an internal tripartite structure, is characterised by a normal grading sandstone base, followed by muddy siltstone middle unit and capped with siltstones; the top unit of HEB 2 may in places be partly or completely eroded. The boundary between the lowest unit and the middle unit is gradual, whereas that between the middle unit and the top unit is sharp. HEB 2 may be developed by up-dip muddy substrate erosion. HEB 3, with a total thickness up to 10 cm and an internal bipartite structure, is characterised by a basal massive sandstone sharply overlain by a muddy siltstone interval. The upper unit was probably deposited by cohesive debris flow with some plant fragments and rare mud clasts. HEB 3 may be formed by the deceleration of low-density turbidity currents. The distribution of HEBs together with debrites and turbidites implies a continuous evolution process of sediment gravity flows: debris flow → hybrid flow caused by particle rearrangement → high-density turbidity current → hybrid flow caused by muddy substrate erosion → low-density turbidity current → hybrid flow caused by deceleration. [ABSTRACT FROM AUTHOR]

Deposit feeding polychaetes play an important role in the acceleration of the biogeochemical processes of the sediment through bioturbation. Feeding is one of the important factors of bioturbation. However, knowledge of the feeding biology of polychaetes, especially the subsurface deposit feeder, is limited. The objective of this study is to characterize the feeding selection of Perinereis aibuhitensis with different body weights. The animals were fed with natural sediment from their original habitat in the lab. The feed intake and particle size of sediment were measured to find any evidence of feeding selection. A two-way ANOVA showed that the particle size class significantly affected the particle size frequency of the ingested and the remaining sediment (P < 0.05), but the polychaete size class did not (P > 0.05). Bivariate correlation analysis showed that the particle size frequency of sediment, ingested and remaining sediment in different size classes were linearly related (P < 0.05). The nitrogen and organic carbon contents were reduced in the faeces and remaining sediment (P < 0.05). The nitrogen and organic carbon contents were similar in faeces and the remaining sediment among all polychaete size classes (P < 0.05). The results indicated that P. aibuhitensis preferred smaller particles in the sediment, which was limited by the particle size distribution of the sediment in which they live. The nitrogen and organic carbon contents in the faeces might be the thresholds when P. aibuhitensis selects sediment particles as food. These results demonstrated the particle selectivity of P. aibuhitensis, and may be applicable to other subsurface deposit feeding polychaetes. [ABSTRACT FROM AUTHOR]

Forty ditch cutting samples were worked on, twenty each for trace elements and sedimentological analyses. A few of these samples were selected for the analysis of heavy minerals within the Bima sandstone and shale sandstone units. The samples were obtained from Shell Nigeria Exploration and Production Company from a depth of between 2414 m and 2785 m. The results showed high concentration values of Ca and K which indicate a low degree of weathering in the source area of the material forming the reservoir rock. A high concentration of Fe and Ti implies the presence of Fe and Ti bearing minerals in the source materials, and the abundance of metals like Cu (135-1629 ppm) and Zn (233-1411 ppm) implied a fine grain size for the sediments as this supports metal absorptivity. The probability curves indicate that the sediments were transported by saltation and suspension in shallow marine environment. The heavy mineral assemblage indicates that the sediments were mineralogically mature and suggest igneous and metamorphic sources. The sorting pattern shows that the distance of transport of materials was intermediate to far from their source. The reservoir rock of Bima Formation shows evidence of having fair to good potential and can hence hold fluids if other petroleum systems are in place. [ABSTRACT FROM AUTHOR]

The Lower Ordovician Bjørkåsholmen Formation at Flagabro, Scania, southern Sweden, consists of a 0.8 m thick succession of carbonates with three siliciclastic mudstones, 5, 1 and 100 mm thick, intercalated in the central part of the unit. Carbonate and siliciclastic mudstone beds show both normal and inverse grading. The carbonates are mud-rich and subdivided into a mudstone, a wackestone and a packstone facies. Grain types in the carbonates are mostly shells and shell fragments of brachiopods and trilobites. The carbonate rocks are strongly bioturbated seen as in roundish burrows filled with mud and a clear cement; additionally, bioturbation is reflected in the random orientation of shells. The siliciclastic mudstones are subdivided into two facies; one contains large amounts of shells and is in part grain-supported, the other is matrix-dominated and laminated to massive. The succession reflects sedimentation on a low-inclined shelf equivalent to a mid-ramp to basinal setting. Most mud- and wackestones (facies 3 and 4) represent fair-weather sedimentation, and the intercalated wacke- and packstones (facies 4 and 5) represent concentration of shell debris during high-energy storm. The siliciclastic mudstones in the central part of the succession reflect deposition in a basinal setting. The entire Bjørkåsholmen Formation at Flagabro is equivalent to a lowstand of third (?) order without a well-developed internal cyclicity and is in that respect similar to the Bjørkåsholmen Formation of Öland, but different from the age-equivalent Norwegian sections. [ABSTRACT FROM AUTHOR]

Since the Xiagou Formation was confirmed to be the primary source rock of the crude oil discovered in the Yumen oilfield, geologists have performed many studies on the sedimentology of the formation, source rock evaluation and migration, as well as petroleum accumulation. In this study, the carbonate-bearing mudstones were investigated using synthetic organic and inorganic geochemical analyses to reconstruct the paleo-environment and study the origin of organic matter during deposition in correlation with organic matter enrichment. The analysed samples have total organic carbon (TOC) and S1+ S2values in the range of 0.20–3.39 wt% and 0.07–19.50%, respectively, which indicate fair to good hydrocarbon potential. Biomarker studies on the pyrolysis data of the samples suggest that the predominant origin of the organic matter is terrigenous high plants with partial aquatic algae and micro-organisms, primarily oil- and gas-prone. The trace elements P and Ba are considered to be the main proxies for paleoproductivity, and values for the two elements hosted in samples range from 48 to 1724 ppm (a mean of 658 ppm) and from 322 to 1701 ppm (a mean of 550.34 ppm), respectively, which indicates that the sediments in the Xiagou Formation have high paleoproductivity. Additionally, organic geochemical studies reveal that the sediments were deposited in a lacustrine environment with brackish water (low C31-22R-homohopane/C30-hopane ratios; moderate gammacerane and β-carotane), which is consistent with the medium degree of the Sr/Ba ratio, which ranges from 0.22 to 1.42 (a mean of 0.64). Furthermore, the wide range of Cu/Zn and Rb contents are important indicators of a suboxic to relatively anoxic paleoredox condition. This outcome is consistent with the biomarker parameter Pr/Ph, which ranges from 0.05 to 1.37. Moreover, the major oxides and trace elements [high Fe/Mn, low Mg/Ca, low CIA and the plot of SiO2vs(Al2O3+ K2O + Na2O)] also indicate that the sedimentary paleoclimate was semiarid to arid. Lack of correlation between TOC content and paleo-environment (suboxic, brackish and semiarid) or productivity indicators indicates that the accumulation of organic matter was controlled by combined action, rather than a single factor, such as redox condition or productivity. [ABSTRACT FROM AUTHOR]

The Lower Jurassic (Sinemurian to Pliensbachian) Precipice Sandstone is the oldest formation and a regional aquifer in the Surat Basin, straddling southeast Queensland and northern New South Wales. Time-equivalent units are recorded in the Eromanga (Poolowanna Formation) and Clarence-Moreton (Ripley Road /Helidon Formation) basins. The Precipice Sandstone is generally considered to consist of braided channel deposits, which upwards become increasingly sinuous or meandering and ultimately give way to a lacustrine succession—the Evergreen Formation. Marine influence has been proposed by some, for parts of the Evergreen Formation. The transition from the Precipice Sandstone to the conformably overlying Evergreen Formation is gradual and diachronous leading to stratigraphic nomenclature inconsistency around the boundary. During sedimentological description of the Precipice Sandstone core from one of QGC Pty's ground water wells (Woleebee Creek GW4) ‘tidal’ features (flaser and wavy bedding, synaeresis cracks, clay drapes andLockeiatraces) were recorded. Biostratigraphy samples contained ‘brackish’ or coastal margin flora supporting the tidal interpretation. Although not sampled for biostratigraphy, similar ‘tidal’ facies have been noted where the Precipice Sandstone crops out in the Carnarvon Gorge section of Carnarvon National Park (Queensland), ∼200 km from the Woleebee Creek GW4 well, suggesting widespread development of a tidal system or systems. The Precipice Sandstone can be divided into an upper and lower unit; each has a distinct sedimentological and electric or wireline-log character, which are described and have been mapped in over 750 wells across the Surat Basin. [ABSTRACT FROM AUTHOR]

Sediment avalanche from delta ramp is one of the significant development mechanisms for a turbidite system in a lacustrine basin. To advance our understanding of deep-water sedimentary processes in a lacustrine delta ramp, delta-fed turbidites in the Eocene Dongying depression of the Bohai Bay Basin were studied using core data, 3-D seismic data and well log data. Sandy debris flows, muddy debris flows, mud flows, turbidity currents, slides, sandy slumps and muddy slumps were interpreted based on the identification of lithofacies. Data indicates that deep-water sedimentary processes in the study area were dominated by debris flows and slumps, which accounted for ∼68% and 25% (in thickness) of total gravity flow deposits, respectively; turbidity-current deposits only accounted for ∼5%. Mapping of turbidites showed that most were deposited after short-distance transportation (<20 km), restricted by the scale of deep-water areas and local topography. Channels, depositional lobes, debris flow tongues, muddy turbiditic sheets, slides and slumps were identified in a delta-fed ramp system. Slides and slumps were dominant at the base of slopes or at the hanging walls of growth faults with strong tectonic activity. Channels and depositional lobes developed in gentle, low-lying areas, where sediments were transported longer distances. Sand-rich sediment supply, short-distance transportation and local topography were crucial factors that controlled sedimentation of this ramp system. Channels generally lacked levees and only produced scattered sandstones because of possible hydroplaning of debris flow and unstable waterways. In addition to lobes, debris flow tongues could also be developed in front of channels. These findings have significant implications for hydrocarbon exploration of deep-water sandstone fed by deltas in a lacustrine basin. [ABSTRACT FROM AUTHOR]

In the upper greenschist to granulite grade rocks of the Willyama Supergroup at Broken Hill, Australia, earlier recognition of metamorphosed graded bedding in siliciclastic metasedimentary rocks led to interpretations of these rocks as deep-water turbidites. However, graded beds can also be deposited in shelfal environments below storm wave base. This study identified other tempestite features including wave oscillation ripples, hummocky cross-stratification and swaley cross-stratification indicating that deposition took place above the wave base of the larger storms. Albitised metasedimentary rocks of the upper Thackaringa Group show structures such as swaley cross-stratification typical of shallow-water conditions above fair-weather wave base. Deposition of the Broken Hill Group commenced with muddy Allendale Metasediments conformable on the Thackaringa Group. The Ettlewood Calc-Silicate Member, originally a dolomitic, siliceous sediment, is interpreted as coastal sabkha indicating onset of a marine transgression. The Parnell Gneiss represents a volcanic or volcaniclastic interruption, heralding gradually increasing input of sand in the Freyers Metasediments reaching a maximum in middle Freyers Metasediments, followed by an abrupt reversion to mud, still influenced by wave action. An open marine shelf is interpreted, possibly 30 m deep (no more than 100 m) in the final stage of a developing rift. The Broken Hill Group terminated with the massive Hores Gneiss volcanic unit. Sedimentation of the siliciclastic Sundown Group took place in similar conditions, commencing with a muddy interval overlying the Hores Gneiss. The shallowing produced by ∼90 m thickness of volcanic/volcaniclastic Hores Gneiss was compensated by subsidence. Paragon Group deposition commenced with substantial black mud, resulting from isolation from the sand supply and probably isolation from the sea. A fresh connection to the sea led first to the deposition of dolomitic carbonate (King Gunnia Calc-Silicate Member), then to deposition of parallel-laminated fine sand below wave base (upper Cartwrights Creek Metasediments), followed by ripple cross-laminated sand above wave base (Bijerkerno Metasediments). The Dalnit Bore Metasediments show abundant very thin graded silt–mud units possibly deposited below storm wave base, and thicker units of stacked wave oscillation ripples deposited above the wave base of larger storms. The Broken Hill orebody is hosted by altered Broken Hill Group metasedimentary rocks deposited at water depths of ∼30 m. Unless the ore fluid temperature was less than 150°C, it is likely that the orebody formed below the seafloor: at such shallow-water depths, the confining pressure would be inadequate to suppress boiling of hotter rising hydrothermal fluids. [ABSTRACT FROM AUTHOR]

Upper Cenozoic fluvial gravels in the Canberra region are quartz-dominated (>95 vol% quartz), whereas modern bedload sediments contain less than 50 vol% quartz and a range of lithologies that broadly reflect the catchment geology. Potential reasons for the compositional difference include changes in catchment geology, sediment transport distance, post-depositional weathering and regolith history. Breakage of unsound clasts during transport does not explain the difference because sediment transport distances in the Cenozoic were similar to today. Post-depositional weathering of less resistant clasts is ruled out because the Cenozoic gravels are clast-supported and preserve original bedding. During much of the Cenozoic, rainfall was significantly higher than the present, and rainforest species were present in the local and regional vegetation. Weathering regimes were likely very different from today, and deep weathering of catchment lithologies may have favoured the supply of quartz-rich gravelly sediment to the river systems. [ABSTRACT FROM AUTHOR]

Intermittent rivers are defined as rivers with a high seasonality in water, sediment transport and habitat. In this study, an attempt is made to outline the major hydro-sedimentological characteristics of intermittent rivers systems using the examples from the Maidan and Shakar-Dara rivers in Kabul region of the Kabul river basin. As dominant hydrological characteristics of intermittent rivers, the interaction between surface water and groundwater is studied by correlating the precipitation, evapotranspiration, river discharges and groundwater level fluctuations in wells located in the vicinity of the rivers. Suspended sediment transport and river bed sediments are in a further step studied to understand the sedimentological behaviour of these river systems. The characteristics of the catchment area such as geology, land cover, land use and dry periods are studied to show their influence on the suspended sediment transport. Field observations and satellite images are used to investigate the morphology of the selected rivers. Results show that precipitation, in particular during the winter and early spring months exceed the evapotranspiration and are providing the main water source for irrigation and groundwater recharge. The analysis reveals that the seepage loss through the river bed contributes significantly more to the groundwater recharge than precipitation. An increase in suspended sediment concentrations in Maidan river are observed by comparing historic (1965–1968) and recent (2012–2015) data. In addition, higher suspended sediment concentrations are observed in Maidan river compared to Shakar-Dara river. The higher concentrations can be linked to the lower percentage of vegetated area in its catchment compared to the Shakar-Dara catchment as well as to its finer sediment grain sizes of its bed and banks. Morphological investigations indicate single and multi-thread (braided) channels are the most common planform types for Shakar-Dara river, however, at Maidan river with gentle slopes, a meandering tendency with various sinuosities can be observed. [ABSTRACT FROM AUTHOR]

The cross-shore profile and the textural distribution of foreshore sediments of Ganpatipule beach along Maharashtra coast covering two annual cycles are examined. Ganpatipule beach depicts erosion and accretion of the berm, reduction and widening of foreshore widths during the monsoon (June–September) and post-monsoon (October–May), respectively with net sediment accretion during the study period due to the changes in the wave characteristics. A direct correlation is observed between the median sediment grain size and beach-face slopes signifying high wave energy ensuing to a gentle to very gentle slope. The sediments are mainly medium grain size, moderately well sorted, bimodal, very fine skewed to very coarse skewed and very platykurtic to very leptokurtic in nature. The binary plots of the textural parameters (mean, skewness, kurtosis, and standard deviation) depicted a characteristic beach environment of deposition. The study shows that the sediment is concentrated in the environment of rolling and bottom suspension. The study on grain size distribution of sediments could be used to assess the wave energy condition prevailing along the coastal area. [ABSTRACT FROM AUTHOR]

The Middle Ordovician (Dapingian–middle Darriwilian) “orthoceratite limestone” is documented in its traditional type area at Kinnekulle in the province of Västergötland in southern Sweden. Detailed field studies combined with systematic qualitative and quantitative analyses of carbonate microfacies at high stratigraphic resolution show that this suite of cool-water carbonate rocks is more variable than is suggested by its overall homogeneous macroscopic appearance. Long-term changes in carbonate textures and fossil grain assemblages, together with pervasive rhythmic/cyclic patterns, suggest a strong influence from sea level on microfacies characteristics. Assessment of the results in light of regional facies patterns indicates that the cool-water “orthoceratite limestone” behaved much like “model” siliciclastic sedimentary systems, in that carbonate texture varied with depositional depth as particle size of siliclastics does. Carbonate texture thus appears to reflect absolute depth well, whereas grain assemblages record high-frequency cycles of changes in both sea level and substrate conditions. A relative sea level curve compiled from the collective data shows excellent agreement with previously published curves based on different proxies. The most important factor for the long-term establishment and regional dominance of the “orthoceratite limestone” throughout much of the Early and Middle Ordovician appears to have been a limited terrigenous sediment input to the Baltoscandian paleobasin. Hence, much of the regional facies zonation may reflect distance from weathering sources rather than bathymetric conditions. [ABSTRACT FROM AUTHOR]

Investigations of modern coseismic ground surface deformation where fault rupture is absent typically rely on remote sensing techniques. We used monitoring of salt marsh vegetation and substrate for 3 years after the 22 February 2011 Christchurch earthquake (MW 6.2) to document the biological response to vertical deformation, to provide estimates of the amount of uplift and subsidence and ground-truth remote sensing data. Comparison of vegetation-derived vertical deformation with estimates from remote-sensing techniques (Light Detection and Ranging, Global Positioning System and Differential Interferometric Synthetic Aperture Radar) shows good agreement at sites where several decimetres of vertical movement occurred, and less agreement where smaller amounts of vertical movement occurred and/or where vegetation-monitoring sites were affected by differential movement of artificial structures such as roads and breakwaters. Biological and sedimentological changes observed in salt marshes around the Avon–Heathcote Estuary/Ihutai (AHEI) as a result of the 22 February 2011 Christchurch earthquake are likely to be preserved as subtle geological signatures in restricted locations around the AHEI. [ABSTRACT FROM AUTHOR]