Sediment Recycling Research Articles

Tracking sources and paleotectonic settings of Mesozoic sandstones in interlinked rift basins of western India: An integrated approach using petrography and heavy mineral chemistry

Based on integration of field, petrographic and heavy mineral chemical data, this study highlights the source and tectonic setting of the Mesozoic sandstones of Kutch, Saurashtra, Narmada and Cambay basins at the western margin of India, formed by the progressive splitting of the eastern Gondwanaland. The Kutch Basin is dominated by arkosic sandstone, whereas Saurashtra, Narmada and Cambay basins show the predominance of sub-arkose and sub-litharenite. The modal analyses of framework grains in Kutch sandstones indicate basement uplift and transitional continent settings. In contrast, the sandstones of Saurashtra, Narmada and Cambay basins bear imprints of recycled orogenic and craton interior belts. The presence of abraded and detrital quartz overgrowth and rounded zircons in most sandstones reveal the recycling of sediments in these basins. Tourmaline and rutile mineral compositions constrain the possible lithology of source rocks. The tourmaline mineral chemistry (Ca-Fetot-Mg plot) suggests the derivation of sediments from various sources, including Li-poor granitoids associated with pegmatites, aplites, Ca-poor metapelites, metapsammites and quartz-tourmaline-rich granitic rocks. The compositions of rutile grains (Cr vs. Nb plot) in sandstones indicate metapelitic sources. The gamut of all mineral chemical data supports the predominance of sediment sources from quartzo-feldspathic rocks with minor inputs from mafic rocks. Based on available paleocurrent data and correlation of source compositions, we infer that the Mesozoic sediments of Kutch, Saurashtra, Narmada and Cambay basins were primarily sourced by various lithologies of the Aravalli Craton. The Narmada Basin possibly received additional sediment input from the Bundelkhand Craton.

Contribution of recycled sediments to the mantle reservoir beneath Hainan Island: Evidence from Sr, Nd, Pb, Hf, and Mg isotopic analyses of Late Cenozoic basalts

Magnesium isotopes are a useful tool for constraining the origin of basalts with EM-like isotopic signatures in relation to ancient subducted slabs and recycled materials incorporated in mantle plumes. In this study, we present new SrNdPbHf and Mg isotopic data that were used to determine the origin of the basalt on Hainan Island and investigate the EM mantle reservoir beneath the island. Cenozoic basalts from northern Hainan Island are mainly tholeiitic, with a small amount of alkaline basalts. The Hainan basalts exhibited depleted SrNd isotopic compositions and EM2-like Pb isotopic signatures. The δ26Mg values of the Hainan basalts ranged from −0.40‰ to −0.28‰. The origin of the low δ26Mg signature can be attributed to carbonate sediments from recycled oceanic slab. Hainan basalts show a negative concave curve relationship between 87Sr/86Sr and εNd values, a positive relationship between 206Pb/204Pb and 207Pb/204Pb values and exhibit an evolution trend from depleted mantle towards marine sediments. This indicates that Hainan Island basalts can be explained by the mixing between depleted mantle and marine sediments. Most Hainan basalts have higher K/U × 10−3 and Ba/Th ratios than primitive mantle (K/U × 10−3 ≈ 11.8, Ba/Th ≈ 83), moreover, display highly correlated K/U × 10−3 and Ba/Th compositions with low-pressure (6–8 GPa) carbonated melt released from initial sediments. Therefore, we speculate that the primitive mantle peridotite, coupled with the low-pressure carbonated melt, ultimately became the mantle source of Hainan Island basalts.

Recovery and environmental recycling of sediments: the experience of CNR-IRET Pisa

Recovery and environmental recycling of sediments: the experience of CNR-IRET Pisa

Near-zero 33S and 36S anomalies in Pitcairn basalts suggest Proterozoic sediments in the EM-1 mantle plume

Volcanic rocks erupted among Pitcairn seamounts sample a mantle plume that exhibits an extreme Enriched Mantle-1 signature. The origin of this peculiar mantle endmember remains contentious, and could involve the recycling of marine sediments of Archean or Proterozoic ages, delaminated units from the lower continental crust, or metasomatized peridotites from a lithospheric mantle. Here, we report the sulfur multi-isotopic signature (32S, 33S, 34S, 36S) of 15 fresh submarine basaltic glasses from three Pitcairn seamounts. We observe evidence for magmatic degassing of sulfur from melts erupted ∼2,000 meters below seawater level (mbsl). Sulfur concentrations are correlated with eruption depth, and range between 1300 ppm S (collected ∼ 2,500 mbsl) and 600 ppm S (∼2,000 mbsl). The δ34S values can be accounted for under equilibrium isotope fractionation during degassing, with αgas-melt between 1.0020 and 1.0001 and starting δ34S values between −0.9‰ and +0.6‰. The δ34S estimates are similar or higher than MORB signatures, suggesting the contribution of recycled sulfur with a ∼ 1‰ 34S enrichment compared to the Pacific upper mantle. The Δ33S and Δ36S signatures average at +0.024±0.007‰ and +0.02±0.07‰ vs. CDT, respectively (all 1σ). Only Δ33S is statistically different from MORB, by +0.02‰. The Δ33S enrichment is invariant across degassing and sulfide segregation. We suggest it reflects a mantle source enrichment rather than a high-temperature fractionation of S in the basalts. Despite the small magnitude of the 33S-36S variations, our data require a substantial amount of recycled sulfur overwhelm the Pitcairn mantle source. We show that models involving metasomatized peridotites, lower crust units, or Archean sediments, may be viable, but are restricted to narrow sets of circumstances. Instead, scenarios involving the contribution of Proterozoic marine sediments appear to be the most parsimonious explanation for the EM-1 signature at Pitcairn.

Trans-Saharan Belt Provenance: A Potential Source for the Ordovician Succession of the Balkan Terrane (Svoge Unit) - Clues from LA-ICP-MS Detrital Zircon Dating Analysis

Two sandstone samples from the upper and lower part of the Ordovician succession of Svoge Unit were analyzed in order to determine their detrital zircon U–Pb age spectra using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). One sample was collected from the Hirnantian siliciclastic glaciomarine deposits of the Sirman Formation. The other sample is amiddle Darriwilian sandstone from the lower half of the Grohoten Formation. Additionally, micropetrographic studies were performed. They are composed predominantly of detrital monocrystalline quartz grains with uniform or rarely undulose extinction and only sporadically presented feldspar grains, muscovite flakes and single rock fragments. The heavy mineral assemblages are also characterized mostly by detrital zircon. As suggested from previous studies of the Hirnantian glaciomarine deposits of Sirman Formation, the provenance of siliciclastic material was most probably associated with sedimentary recycling of maturesands deposited across the North Gondwana Platform. Multi-dimensional scaling statistical technique allowed a reliable objective identification of the potential source areas in Northern Africa and palaeogeographic reconstructions were made. Both samples are close to the Trans-Saharan Belt provenance, which is the most probable source for the detrital component. Our data supportthe idea proposed by previous researchers that the present-day position of some of these terranes implies significant dextral strike-slip displacement, probably due to the movement on the Pangea megashear during the Carboniferous and Permian.

Understanding ancient tectonic settings through detrital zircon analysis

The fertility and heterogeneity of source rocks play important roles in determining the age distribution of detrital zircon populations that accumulate in sedimentary basins. Detrital zircon samples in active convergent tectonic settings are typified by a dominance of well-defined young age modes associated with an arc/magmatic orogenic belt, while passive margins and extensional settings more commonly express dispersed polymodal age populations reflecting more extensive, geologically heterogeneous catchments and greater sediment recycling. Two newly defined metrics relating to (i) the temporal difference between the 10th and 50th percentiles of a detrital zircon age population, and (ii) a modified χ2-distribution analysis of age population modality and dispersion, provide a powerful means of distinguishing between geologically active convergent systems and divergent/passive margin basins. Importantly, this tool does not require knowledge of depositional age. This “age distribution fingerprint” is assessed in three distinct Cenozoic to Proterozoic case-studies to demonstrate the tectonic resolution of the approach and potential in refining views of basin evolution. The age distribution fingerprint offers the ability to characterize sediment routing histories and investigate tectonic settings since the onset of subduction related plate tectonics, even where stratigraphic constraints are lacking.

Stratigraphy and palaeogeography of the Cretaceous Blue Spur Conglomerate, Otago, New Zealand

ABSTRACT The non-marine Blue Spur Conglomerate in southeast Otago hosts the largest gold paleoplacer in New Zealand, but its formal stratigraphic relationships have thus far not been clear. The name reflects the extensive formation of ferrous iron-bearing diagenetic clay. We present a reference section for the unit, which is in part late Haumurian in age (c. 81–66 Ma). The unit is defined as a formal Member of the nearby, but not contiguous, Late Cretaceous Taratu Formation, Onekakara Group, Haerenga Supergroup. The Blue Spur Conglomerate contains three principal clast types: proximal schist debris, quartz pebbles and recycled distal greywacke cobbles, whereas the wider Taratu Formation is dominated by quartz pebble conglomerate with subordinate lithic clasts. Rare clasts of silicified quartz pebble conglomerate (silcrete) in both units attest to the recycling of older mature quartz sediments. The Blue Spur Conglomerate formed locally at the base of active normal fault scarps that controlled a broad valley in which the regionally extensive Taratu Formation accumulated. Detrital gold in the Blue Spur Conglomerate had both proximal and distal sources, whereas the Taratu Formation elsewhere received only distal gold.

Sustainable restoration of anoxic freshwater using environmentally-compatible oxygen-carrying biochar: Performance and mechanisms

The long-term decline in dissolved oxygen (DO) levels in freshwater systems including rivers and lakes has become a worldwide concern, which can threaten biodiversity, nutrient biogeochemistry, water quality and ultimately human health. Herein, we report a sustainable restoration strategy for anoxic freshwater using local sediment-based biochar as novel oxygen nanobubble carriers. Column incubation experiments were conducted with water and sediment samples from an urban tributary of the Yangtze River. The oxygen-carrying sediment-based biochar (O-SBC) showed long-lasting re-oxygenation performance for anoxic river waters during 28-day period, in which DO was rapidly elevated from ∼0.14 to ∼7.87 mg/L and gradually maintained at ∼4.78 mg/L until the end. O-SBC with multiple functions switched the sediments from a source to a sink of nutrients, and its release of oxygen nanobubbles contributed further decrements of 66.3% NH4+-N and 142.9% PO43−-P except for physical blocking and physicochemical adsorption. Notably, a comprehensive focus on restoration mechanism was explored in view of microbial community response. The re-oxygenation was followed by a ∼5.05% increase of bacterial diversity (Shannon index) in water, but a ∼2.40% decrease in sediments. A proliferation of some specific aerobic populations was observed, of which the nitrifying Nitrospira abundances were ∼10-fold higher in the water from O-SBC than the control. Additionally, functional genes involved in nitrous oxide reduction, polyphosphate synthesis/degradation, and thiosulfate oxidation were also enriched. Taken together, our findings can not only expand the promising candidates for oxygen nanobubble carriers based on sediment recycling, but also highlight the microbial molecular mechanisms for anoxic freshwater restoration based on nutrient cycle regulation.

Apatite and zircon geochemistry for discriminating ore-forming intrusions in the Luming giant porphyry Mo deposit, Northeastern China

The Luming giant porphyry Mo deposit in NE China host >0.89Mt Mo, but which intrusion induced the Mo mineralization is still in debated. In this study, apatite and zircon geochemistry from three mentioned ore-forming granites, namely monzogranitic porphyry (MGP), granodiorite (GD) and monzogranite (MG) in Luming ore district are presented in order to constrain the real ore-forming granite. Apatite and zircon U-Pb dating of the MGP, GD and MG yield a crystallization age of ca. 177 Ma, ca. 187 Ma and ca. 186 Ma, respectively. Whole-rock geochemistry, in-situ apatite Sr-Nd and zircon Hf isotopic compositions suggest that these granites formed by partial melting of juvenile lower crust with different depth. Both the MGP and GD have adakitic affinities and the depth of their magma source is > 45 km with garnet as residual phase, whereas the source depths for the MG was < 33 km with plagioclase as residue. Apatite and zircon geochemical features indicated that the magma of MGP and GD have higher oxygen fugacity, water contents and lower Ti-in-zircon temperatures than these of the MG, which make the MGP and GD are more favorable for Mo mineralization, but the less volume of GD limited its metallogenic potential. Decoupled Nd-Hf isotopes of the MGP, GD and MG could be induced by recycled ocean sediment added in their source region, and the addition of recycled sediments could be account for Mo concentrate in the source and regional Mo mineralization.

Provenance, source weathering, and tectonic setting of the lower Cambrian Shuijingtuo Formation in the Middle Yangtze area, China

The organic-rich shale of the Lower Cambrian Shuijingtuo Formation is an important hydrocarbon source rock in South China. The geochemical characteristics of this shale were investigated to determine the provenance, weathering conditions, sedimentary recycling, paleoclimate, and tectonic setting of the Shuijingtuo Formation in Yichang in the Middle Yangtze area. The shale is relatively enriched in CaO, P2O5, Mo, U, V, Cd, and Cu. The rare earth element (REE) patterns of the shale exhibit light rare earth element (LREE) enrichment and heavy rare earth element (HREE) depletion. It has weak negative Eu and Ce anomalies, which are similar to the characteristics of passive margin deposition. The analysis of the carbonate dilution effect conducted in this study reveals that carbonate dilution has a greater effect on the MgO, Ba, Sc, and Zr contents. The provenance discrimination diagrams suggest that the shale is primarily derived from a mixture of intermediate and felsic igneous source rocks, which were similar to Tonalite-trondhjemite-granodiorites (TTGs) in composition. The chemical index of alteration (CIA) values and the A–CN–K ternary diagram indicate that the source area of the shale experienced a low degree of chemical weathering under a cold and arid climate in the early period and a moderate degree of chemical weathering under a warm and humid climate in the later period. The relationship between Zr/Sc and Th/Sc indicates that the shale was deposited by the first cycle of sedimentation rather than via reworking. The discriminant function diagrams, major element ratios, immobile trace element ratios, and ternary relationships between La, Th, Sc, Zr, and Co indicate that the source rocks were deposited in a passive margin tectonic setting. It is suggested that the Ezhong old land, which is predominantly composed of the Huangling granite and the Kongling complex (composed of intermediate and felsic igneous rocks) was the source area.

Sediment Recycling and the Evolution of Analog Orogenic Wedges

AbstractIn convergent systems, the interplay between tectonics, erosion, and sedimentation controls the orogenic evolution. The nature of the interactions between these factors is still elusive due to the complex feedbacks that operate across different temporal and spatial scales. Here, we investigate these feedbacks with analog models of landscape evolution designed to account for both tectonic forcing and surface processes, using a water‐saturated granular material that allows to simulate contemporary brittle deformation and surface processes. The deformation is imposed by the movement of a rigid backstop, and surface processes are triggered by simulated rainfall and runoff. We vary the convergence velocity, rainfall rate, and basal angle of the box, testing how different boundary conditions affect the balance between tectonics and surface processes. We measure the competition between input fluxes (tectonics) and output fluxes (erosion) of material, showing how sedimentation strongly affects the balance between these fluxes. The results suggest that the experimental equilibrium between tectonics and erosion can be achieved, in the analog models, only for low convergence rates (about 10 mm hr−1) and/or for high basal angle (&gt;2°, limited sedimentation). If the foreland is overfilled with sediments and/or if convergence velocity is higher, channels decrease their erosional efficiency, moving the dynamic equilibrium between tectonics and erosion toward the former.

Syntectonic Sediment Recycling Controls Eolian Deposition in Eastern Asia Since ∼8 Ma

AbstractGlobal cooling and/or Tibetan Plateau uplift have long been regarded as the principal drivers of late Cenozoic central Asian aridification and the resulting widespread accumulation of eolian deposits in eastern Asia. However, these two factors are unable to form large source areas of fine‐grained sediments enhancing eolian deposition synchronously from northern Tibet to North Pacific. Here we provide magnetostratigraphic and detrital apatite fission‐track evidence for a major sediment recycling event in northern Tibet at ∼8 Ma, coeval with a sudden increase in eolian deposition, which we ascribe to syntectonic erosion of uplifted friable fluvio‐lacustrine sediments and selective entrainment by the westerly winds during basin deformation. Our results emphasize the importance of widespread and persistent occurrence of fine‐grained sediments along the pathway of westerlies to produce voluminous dust deposits. These findings suggest that the onset of eolian deposition may not be directly related to global cooling or uplift of mountain ranges.

Petrography and geochemistry of the Middle Jurassic Fort Member Sandstone, Jaisalmer Formation, Western India: Implications for weathering, provenance, and tectonic setting

Detrital mineralogy, major oxides, trace, and rare earth elements (REE) were examined in the Middle Jurassic Fort Member Sandstone (FMS) of the Jaisalmer Formation in Western India to understand palaeoweathering, provenance of sediments, and to decipher the tectonic setting. The sandstones are classified as arkose to sub‐litharenite types according to their relative percentages of quartz, feldspar, and lithic fragments, and major elemental ratios. The values of Chemical Index of Alteration (67–85), Plagioclase Index of Alteration (78–97) and Chemical Index of Weathering (83–97) along with A‐CN‐K diagram suggest moderate to intense chemical weathering in the source region. Presence of fresh feldspars and dominance of monocrystalline quartz, showing both parallel and undulose extinction, indicate plutonic and volcanic felsic igneous provenance. Contribution from metamorphic orogen sources is indicated by the lithic fragment population. Various geochemical parameters such as Th/Sc, Cr/Th, Ti/Zr, and Eu/Eu* support a dominant felsic provenance. Higher Zr/Sc ratios relative to the magmatic Zr/Sc‐Th/Sc trend, higher Zr and Hf concentrations in the FMS indicate some extent of sedimentary recycling and zircon sorting. LREE enrichment, flat HREE pattern, negative Eu anomaly and trace element ratios, in conjunction with palaeocurrent data, indicate a likely sediment contribution from basement source terrains including Erinpura‐Mount Abu‐Sirohi granites, Malani Igneous Suite, and Aravalli‐Delhi orogens. The major and trace element tectonic setting discrimination diagrams for the FMS indicate a passive margin setting.

The role of antecedent morphology and changing sediment sources in the postglacial palaeogeographical evolution of an incised valley: The sedimentary record of the Ría de Arousa (NW Iberia)

Incised valleys represent dynamic coastal and shelf systems in continuous change in response to different temporal and spatial scales. Their sedimentary record offers valuable data to unveil the effect of different drivers, such as relative sea-level rise, on the evolution of coastal systems and provide invaluable records of palaeoenvironmental changes. In this work, the palaeogeographical evolution of the Ría de Arousa (NW Spain) from the Last Glacial Maximum to the present is reconstructed by identifying the main elements of sedimentary architecture. These elements are characterised using a multidisciplinary approach combining seismic, sedimentary, geochemical and palynological data. The general succession of the sedimentary infilling of the incised valley records an overall transgression in response to postglacial sea-level rise. A large fluvial valley evolves into a tide-dominated estuary and later to a wave-dominated estuary as it is progressively flooded. The complex interaction between variable rates of relative sea-level rise and the antecedent morphology exerts a strong control on hydrodynamics within the valley controlling the sediment dynamics and facies distribution, displaying some similarities with conceptual facies models for tide- and wave-dominated estuaries. The analysis of sediment sources also denotes significant changes in response to varying hydrodynamic regimes and climate, shifting from a predominant fluvial source in the earliest phases of the transgression to an increase in local sources (cliffs and local coastal deposits), including a likely reworking of older deposits (sediment recycling) during the Early Holocene. These changing sediment sources may have a clear impact on the palynological signal recorded within the incised valley, hypothetically masking and overprinting the climatic signal during phases of intense reworking of older deposits. Sediment recycling seems extensive within the incised valley and represents a key process that needs to be evaluated to understand the source-to-sink sediment flux to the deeper ocean. Its impact on the sedimentary records may have major implications for palaeoenvironmental studies in coastal settings, stressing the importance of applying multi-proxy approaches. • Palaeogeographical evolution of an incised valley from Last Glacial Maximum to present. • Multidisciplinary analysis of elements of sedimentary architecture • Antecedent morphology exerts a strong control on hydrodynamics and facies distribution. • Shift from a fluvial source to local sources, including reworking of older deposits. • Changes in sediment sources may have an impact on the palynological signal recorded.

Life-cycle assessment of compressed bricks using Cameron Highlands reservoir sediment as primary material

Disposal of dredged sediments has recently been linked to environmental and health issues, rather than bringing any economic value to the country. Furthermore, the overexploitation of clay for brick production is destructive to the environment. Hence, it is essential to develop a decisive method to minimize the land and water pollution resulting from improper disposal as well as lessening the consumption of natural resources in the brick production. The key objective of this study is to identify environmental impacts of compressed bricks using Cameron Highlands reservoir sediment to replace clay in the compressed brick. The life cycle assessment is conducted in a cradle-to-gate manner. This study also presents the avoided process of recycled sediments in the life cycle assessment. The damage categories are quantified in terms of human health, ecosystem and resource availability by using ReCiPe Endpoint indicators. According to the results of the life cycle assessment, the compressed sediment brick is favourable from an environmental perspective. In comparison to compressed clay brick, the compressed sediment brick offers promising options for the long-term because it contributes high environmental performance among all the impact and damage categories assessed in this study.

Gaining from loss: Detrital zircon source-normalized α-dose discriminates first- versus multi-cycle grain histories

Detrital zircon U–Pb ages are widely employed as an archive of geological processes through time. Changes in detrital zircon age patterns within sediments reflect changes in source areas that are often related to tectonic and/or climatic processes. However, discrimination of first-cycle and multi-cycle detrital zircon with primary crystalline and secondary sedimentary sources, respectively, can be challenging using only crystallisation age constraints. Here, we present U–Pb geochronology of detrital zircon from modern fluvial and littoral environments on the Scott Coastal Plain in Western Australia to investigate the use of α-dose to identify sedimentary recycling. The majority of 1032 concordant U–Pb ages are interpreted to be ultimately sourced from the local basement. However, U–Pb ages do not reflect the areal extent of source rocks and indicate significant reworking of coastal plain sediments. A novel metric – source-normalized α-dose – demonstrates predominant detrital zircon routing via recycling through intermediate storage. This metric is defined as the ratio of the average α-dose (a measure of metamictization) of detrital zircon belonging to a characteristic age group and the average α-dose of zircon grains within the corresponding source crystalline basement. Average values of source-normalized α-dose of detrital zircon populations <1 are interpreted to reflect selective removal of more labile (metamict) grains via attrition and diagenesis, indicating greater grain transport and recycling, whereas values of c. 1 signify shorter transport and a first-cycle origin. Application of this approach to ancient clastic systems is supported by consistency of results with independent indicators of progressive sedimentary recycling and/or transport. Source-normalized α-dose is an internal measure using zircon grain chemistry (U and Th), and avoids bias associated with multi-mineral measures of sediment recycling that may be related to source fertility. Additionally, source-normalized α-dose uses measures typically captured during routine U–Pb geochronology. Source-normalized α-dose of detrital zircon provides an additional method to address sedimentary source-to-sink transport and recycling, and ultimately allows more robust interpretation of U–Pb zircon data.

Geochemistry of Upper Eocene-Oligocene sandstones from Tuzgölü Basin (Central Anatolia)

In this study, mineralogical and geochemical features of Upper Eocene-Oligocene sandstones exposed by the Tuzgölü Fault Zone (TFZ) at the eastern border of the Tuzgölü Basin were investigated. The absence of zircon enrichment in the Zr/Sc-Th/Sc diagram indicated no sedimentary recycling. This shows that the sandstones are first cycle sediments, that is, the material transported directly from the source. Critical element ratios for provenance such as La/Sc, La/Co, Th/Sc, Th/Co, Th/Cr, Zr/Sc, Zr/Co, Ba/Sc, and Ba/Co, Th/Sc-Eu/Eu* diagram and average Rare Earth Element (REE) pattern suggest a provenance in “intermediate magmatic” composition. The variation in the negative Ce anomaly effect observed between the lower and upper parts of the sequence indicates variation in the oxygen level of the water. In each of the La-Th-Sc, Th-Co-Zr/10, and Th-Sc-Zr/10 tectonic setting discrimination diagrams, the sandstone average fell onto the “Continental Island Arc” position. This tectonic setting defines the arc that developed along the continental margin of the subduction zone. The tectonic setting found for the basin, supported the evolution model that the Tuzgölü Basin developed as a fore-arc basin.

Depositional age, provenance, and palaeoenvironment of the Lower Permian mudstones in the Qiangtang Basin, Tibet: Evidence from geochronology and geochemistry

The geochronology of tuffaceous sandstone and elemental geochemistry of mudstones in the Lower Permian Zhanjin Formation (well QZ‐5) in the Central Qiangtang Basin were studied to determine their depositional age, provenance, tectonic setting, and depositional conditions. Twenty‐six synchronous igneous zircons from tuffaceous sandstone at 596.5 m have a weighted average U–Pb age of 292.5 ± 2.5 Ma, tentatively constraining the sedimentary age of the Zhanjin Formation to the Early Permian. Low SiO2/Al2O3 and Th/Sc ratios indicate a low sedimentary recycling and compositional maturity for the source area of the Zhanjin Formation mudstones. The low Al2O3/TiO2, moderate‐high Fe2O3/Al2O3, high TiO2/Fe2O3, low‐moderate TiO2/Zr, and moderate Co/Th ratios combined with post‐Archean Australian shale‐normalized rare earth element distributions imply that the provenance of the Zhanjin Formation mudstones was mainly from the mixed mafic and felsic sources that is composed of basalt and rhyolite exposed in the Central Qiangtang Basin. The tectonic discrimination plots, low Fe2O3/TiO2, (La/Ce)N, and high Al2O3/(Al2O3 + Fe2O3) ratios reveal that the studied mudstones mostly formed in rift settings, consistent with the geologic evolutionary history of the Early Permian Qiangtang Basin. Trace element ratios (V/Cr and Cu/Zn), enrichment factors (MoEF), and δCe values combined with sedimentary features indicate that almost all the studied mudstones were deposited in an open marine environment along the continental margin, and were associated with oxic and dysoxic water columns.

Can Bottom Sediments Be a Prospective Fertilizing Material? A Chemical Composition Analysis for Potential Reuse in Agriculture.

Every year, huge amounts of bottom sediments are extracted worldwide, which need to be disposed. The recycling of bottom sediments for soil fertilization is in line with the long-promoted circular economy policy and enables the use of micro and macronutrients accumulated in sediments for soil fertilization. When considering potential agricultural reuse of the dredge sediments, the first necessary step should be to analyze whether the heavy metal content meets the obligatory criteria. Then, the contents of valuable elements required for plant growth and their ratios should be assessed. In this study, the content of nitrogen, organic carbon, phosphorus, and potassium was tested and iron, sulfur, calcium, and magnesium were also analyzed along vertical profiles of sediments extracted from four urban retention tanks in Gdańsk (Poland). The sediments were indicated to have a low content of nutrients (Ntot 0.01–0.52%, Corg 0.1–8.4%, P2O5 0.00–0.65%, K 0.0–1.0%), while being quite rich in Fe and S (0.2–3.3%, 0.0–2.5%, respectively). The C/N ratio changed in the range of 17.4–28.4, which proved good nitrogen availability for plants. The mean values of the Fe/P ratio were above 2.0, which confirms that phosphorus in the sediments would be available to the plants in the form of iron phosphate. To summarize, the bottom sediments from municipal retention reservoirs are not a perfect material for soil fertilization, but they are a free waste material which, when enriched with little cost, can be a good fertilizer. Future research should focus on cultivation experiments with the use of sediments enriched with N, P, Corg.

Detrital zircon U–Pb age analysis of last glacial loess sources and proglacial sediment dynamics in the Northern European Plain

Loess deposits along the northern fringe of the European loess belt potentially record past changes in dust emission from areas proximal to former ice sheets. Recent chronologies from loess deposits across this region generally agree on greatly enhanced dust deposition rates when the Fennoscandian Ice Sheet reached its maximum extent during the late last glacial. However, uncertainties over the material's source and origin limit understanding of the causes of this enhanced dust activity. In particular, loess in southwestern Poland has been attributed to multiple origins, mainly involving glaciofluvial outwash plains along the Fennoscandian Ice Sheet margin and/or local sources in the mountainous areas of the Sudetes and Western Carpathians. Here we apply detrital zircon U–Pb age analyses for a large number of grains recovered from four loess samples taken from different stratigraphic units exposed at Biały Kościół in southwestern Poland, previously luminescence dated to MIS 4–2, to assess loess provenance as well as its temporal evolution during last glacial Fennoscandian Ice Sheet fluctuations. Furthermore, we analysed the detrital zircon U–Pb age spectra of five samples from potential source sediments to constrain the history of sediment recycling and mixing within the Northern European Plain prior to deflation and loess deposition. The broad range of zircon age components detected in the four loess samples suggests both Fennoscandian and closer Peri-Gondwanan proto-sources while a narrow, dominant Carboniferous age peak is consistent with sourcing from the local Strzelin Hills in the Sudetic foreland. However, the presence of both Fennoscandian and Peri-Gondwanan derived grains in samples from potential source sediments reveals that this mixture of sediment sources is widespread across the Northern European Plain, as a result of long-term glacial and fluvial reworking of cover sediments in the proglacial area throughout the Quaternary. Local rivers draining the Sudetic foreland transported this Fennoscandian-Peri-Gondwanan sediment mixture along with particles denuded from the Strzelin Hills, resulting in a nearby, temporally stable dust source for the Biały Kościół loess during MIS 4–2, while dust emission rates were substantially increased during the last glacial maximum. Given that our model for loess formation at Biały Kościół essentially involves sediment distribution via rivers prior to short distance aeolian transport, we infer that the proportion of northern ice sheet derived particles in European loess deposits is mainly controlled by the drainage pattern of major rivers in relation to Pleistocene ice margins where glaciofluvial sediment is abundant. Based on the presence of Fennoscandian derived zircon grains in European loess deposits, we constrain a southern limit of the influence of northern ice sheet dust sources along the central European highlands that currently divide drainage between the Northern European Plain and the Danube Basins.