Sediments North Research Articles

Heavy metal pollution in the nearshore surface sediments north of the Shandong Peninsula and the Western Miao Islands, China

Surface sediment samples (N = 94) were obtained from the west Miao Islands, northern Shandong Peninsula, China, and analyzed for grain size and elements. Based on the classification by Folk and Ward, surface sediments were dominated by silt-sized components, sandy silt, and silt. The mean abundance of heavy metals could be ordered according to Cr > Zn > Ni > Cu> Pb > As> Cd > Hg. According to sediment quality guidelines, surface sediments have a 21 % probability of being toxic. The potential ecological risk index indicates low potential ecological risk, while the enrichment factor and geo-accumulation indices indicate slight to moderate pollution across most of the study area. Pollution load indexes indicate that 38 % of sites are moderately metal contaminated and 62 % of sites are not polluted. The study area was classified according to the level of heavy metal contamination and its sources.

Spatial and temporal distribution of macrobenthos communities and their relationship with secondary front in Hangzhou Bay

Water quality in Hangzhou Bay is inferior (grade 5) because of discharged from Yangtze River and Qiantang River, and from factories around the bay. This study analyzed relationships between the environment and macrobenthic communities at 44 stations throughout Hangzhou Bay, based on samples collected in 2006, from 2016–2018, and in 2021. Long-term spatial and temporal changed in macrobenthos, and the influence of secondary water fronts on community composition, were discussed. Macrobenthos in Qiantang River Estuary was numerically, primarily dominated by crustaceans, and elsewhere by polychaetes. Species that differ most in abundance between four identified regions in the bay were the amphipod Corophium sinensis, clam Potamocorbula laevis, and polychaete Amaeana occidentalis. The abundance and biomass of macrobenthos in different regions differs significantly. Taxa were allocated to six feeding guilds: filter feeders and omnivores predominate in Qiantang River Estuary and south of Hangzhou Bay, while surface and subsurface deposit feeders predominate in sediments north of Hangzhou Bay and in the bay mouth area. Negative correlations were apparent between the abundances of polychaetes Nephtys polybranchia, Magelona japonica, Heterospio sinica, Sabella sp. and A. occidentalis and salinity and pH, while positive correlations were apparent between those of Sternaspis chinensis and Capitellidae indet. Fine-grained fraction (silt and clay) and mid-salinity were more suitable for macrobenthos. The numbers and biomasses of macrobenthic species in the Hangzhou Bay frontal area increased significantly relative to values in adjacent areas. The difference of each area near the front was more than 94%, and the main difference species were polychaetes and mollusks. Our baseline data for this region might ultimately contribute towards improved conservation of regional macrobenthos, and a better understanding of ecosystem health in this highly polluted bay.

Evaluation of Contamination Status, Ecological and Human Health Risks of Heavy Metals in Sediments North of Safaga Bay along the Red Sea, Egypt

Evaluation of Contamination Status, Ecological and Human Health Risks of Heavy Metals in Sediments North of Safaga Bay along the Red Sea, Egypt

Distribution of rare earth elements in sediments of the North China Plain: A probe of sedimentation process

Rare earth elements (REE) are powerful tracers for our understanding of sedimentary provenance and depositional processes. This study investigated geochemical characteristics of REE in 226 sediment samples collected from the piedmont, central and littoral plains of the North China Plain. Results showed that total REE concentrations exhibited a decreasing trend as piedmont > central > littoral, and 82%, 70% and 67% samples had total REE concentrations higher than the value of upper continental crust. The REE concentrations were controlled by sedimentary provenance and sediment physicochemical properties. Ternary diagrams of sandstone classification and Al2O3–CaO + Na2O–K2O reflected that sediments originated from greywackes and they experienced an incipient to intermediate chemical weathering. Average chemical index of alteration (CIA) value was 68, 51 and 55 for sediments from piedmont, central and littoral plains, respectively. Sediment North American Shale Composite (NASC)-normalized patterns were characterized by light REE (LREE) enrichment over heavy REE (HREE) and coherent negative Eu anomaly (Eu/Eu* ranging between 0.57 and 1.00). Value of (La/Yb)NASC ranged from 0.86 to 1.15 (average 1.23), and from 1.03 to 1.49, and from 0.91 to 1.49 in three zones, respectively, indicating REE fractionation occurred from piedmont to littoral during sedimentation processes. A positive correlation between (La/Yb)NASC and total REE concentrations was observed in piedmont and central sediment samples, implying that LREE were preferentially enriched over HREE with an accumulation of REE. This positive correlation was not found in littoral sediment samples, where a general decreasing trend along depth for REE concentrations existed. The findings of this study have an implication for using REE as a tracer in provenance studies from a basin scale.

Distribution and Pollution Evaluation of Nitrogen and Phosphorus of Sediments in Zhangze Reservoir

The nitrogen and phosphorus pollution of sediments has increasingly become the main cause of eutrophication in reservoir. The temporal-spatial distribution features and pollution level of nitrogen and phosphorus of sediments were revealed in Zhangze Reservoir. The nitrogen and phosphorus content of 16 sediment samples were detected, as well as sediment oxygen demand. The temporal-spatial changing rules of nitrogen and phosphorus of sediments were analyzed. The pollution level of sediments was evaluated. The results showed that the total nitrogen content of sediments varied from 506 mg/kg to 4411 mg/kg, the total phosphorus content of sediments varied from 160 mg/kg to 961 mg/kg, and the sediment oxygen demand varied from 1295.7 mg/(m2•d) to 2957.6 mg/(m2•d). The nitrogen and phosphorus content of sediments in north and south section was larger than that in middle section. The temporal variation rule of nitrogen and phosphorus content was that it increased obviously in flood season and decreased obviously in freezing stage. The nitrogen pollution level of most of the sediments was severe pollution, with the most serious pollution near the dam and at the end of the reservoir. The phosphorus pollution level of most of the sediments was mild pollution, with moderate and severe pollution near the dam and at the end of the reservoir.

Provenance of Middle Jurassic sequences in the Northern Qiangtang: implications for Mesozoic exhumation of the Central Tibetan Mountain Range

ABSTRACT The exhumation history of the Central Tibetan Mountain Range (CTMR) in the Qiangtang terrane is important for establishing the boundary conditions prior to the India-Asia collision. Previous studies suggest that the CTMR is a significant provenance for Jurassic sediments in the Qiangtang terrane. The Middle Jurassic sediments north of the CTMR provide crucial information to constrain the timing of exhumation in the source area. Here we present detailed stratigraphic sections and detrital zircon U-Pb geochronology in the northern Qiangtang basin. Sedimentary facies analyses indicate that the Early-Middle Jurassic Quemoco Formation is mainly deposited in the deltaic system and carbonate-platform environment. Upsection, the Middle Jurassic Xiali Formation was deposited in a prodelta environment. Combined analyses of palaeocurrent indicators, conglomerate clast composition and U-Pb age spectra suggest that the CTMR is the main provenance for the Quemoco and Xialai formations; while the Triassic southern Qiangtang strata and Jinsha suture are the secondary source areas. The changes in the specific position of detrital zircon U-Pb age peaks around 500 Ma indicate evolving source terranes. Detrital zircon U-Pb geochronological data from the base of the Quemoco Formation and top of the Xiali Formation constrain the conservative maximum depositional ages to be 174.8 ± 1.0 and 161.7 ± 2.3 Ma, respectively. Combined with previous geochronology data, structural geology, and provenance studies across the Qiangtang terrane, the CTMR experienced rapid exhumation during Middle Jurassic and Late Cretaceous and slow exhumation since Eocene. The Jurassic uplift and exhumation of the CTMR were accompanied by the uplift of the southern Qiangtang terrane. The deformation and exhumation history is in favour of the hypothesis that plateau growth in the south-central Qiangtang terrane initiated during the Mesozoic, which is an important initial condition to quantify Cenozoic growth of the Tibetan Plateau.

Arctic Continental Margin Sediments as Possible Fe and Mn Sources to Seawater as Sea Ice Retreats: Insights From the Eurasian Margin

AbstractContinental margins are hot spots for iron (Fe) and manganese (Mn) cycling. In the Arctic Ocean, these depositional systems are experiencing rapid changes that could significantly impact biogeochemical cycling. In this study, we investigate whether continental margin sediments north of Svalbard represent a source or sink of Fe and Mn to the water column and how climate change might alter these biogeochemical cycles. Our results highlight that sediments on the Yermak Plateau and Sofia Basin exhibit accumulations of Fe and Mn phases compared to average shale. Conversely, sediments from the Barents Sea slope exhibit lower enrichments of Fe and Mn compared to average shale, with the exception of enriched, near‐surface sediment layers. Pore waters from these slope sites provide evidence for Fe and Mn reduction and diffusion of Fe and Mn into near surface sediments, which are susceptible to physical or biogeochemical remobilization. These regional patterns are best explained by the spatial distribution of sea ice coverage and labile organic carbon fluxes to the seafloor. As sea ice continues to retreat and the Yermak Plateau becomes seasonally ice‐free, productivity is expected to increase, which would increase the flux of carbon to the sediments, thereby increasing oxidant demand, and the reduction of Fe and Mn mineral phases. Our results suggest that as sea ice continues to retreat, the Yermak Plateau and other Arctic continental margins could become sources of Fe and Mn to Arctic bottom waters.

Detrital zircon provenance evidence for an early Permian longitudinal river flowing into the Midland Basin of west Texas

ABSTRACT Collision of Gondwana and Laurentia in the late Palaeozoic created new topography, drainages, and foreland basin systems that controlled sediment dispersal patterns on southern Laurentia. We utilize sedimentological and detrital zircon data from early Permian (Cisuralian/Leonardian) submarine-fan deposits in the Midland Basin of west Texas to reconstruct sediment dispersal pathways and palaeogeography. New sedimentological data and wire-line log correlation suggest a portion of the early Permian deposits have a southern entry point. A total of 3259 detrital zircon U-Pb and 357 εHf data from 12 samples show prominent groups of zircon grains derived from the Appalachian (500–270 Ma) and Grenville (1250–950 Ma) provinces in eastern Laurentia and the peri-Gondwana terranes (800–500 Ma) incorporated in the Alleghanian-Ouachita-Marathon orogen. Other common zircon groups of Mesoproterozoic-Archaean age are also present in the samples. The detrital zircon data suggest throughout the early Permian, Appalachia and Gondwana detritus was delivered by a longitudinal river system that flowed along the Appalachian-Ouachita-Marathon foreland into the Midland Basin. Tributary channels draining the uplifted Ouachita-Marathon hinterland brought Gondwana detritus into the longitudinal river with headwaters in the Appalachians or farther northeast. This drainage extended downstream westward and delivered sediments into the Permian Basin near the west terminus of the Laurentia-Gondwana suture. Estimated rates of deposition and proportions of zircons from more local (Grenville) versus more distal (Pan-African) sources indicate that river strength decreased throughout early Permian time. Primary sediment delivery pathway was augmented by minor input from the Ancestral Rocky Mountains and wind deflation of fluvial sediments north and east of the basin. Slope failure associated with early Permian deposition in the southeastern margin of the Midland Basin triggered gravity flows leading to submarine fan deposition.

Why Does the Repaired Len Small Levee, Alexander County, Illinois, US Continue to Breach during Major Flooding Events?

One only needs to study the soil and geologic history and location of the ancient Mississippi and Ohio Rivers to understand why Len Small levee if patched will continue to fail. Much of Dogtooth Bend located in Alexander County, Illinois was originally in the ancient Ohio River valley (Figure 1) alluvial sediments north and east of the confluence with the ancient Mississippi River. The ancient Ohio River valley soils underlain by alluvial sediments and have been easily eroded by the re-aligning modern Mississippi River which now travels through the bedrock controlled Thebes Gap (Figure 2) and into the Ancient Ohio river valley. The primary objectives of this paper are: 1) to explain why Len Small levee, Alexander County, Illinois, US will continue to breach during major flooding events if repaired and 2) to develop a new combined raised causeway and levee system which will provide a Mississippi River floodwater bypass, be sustainable, encourage and fund a land use change, restore the degraded highway road beds, protect remaining Dogtooth Bend farmsteads and farmland that have not yet been degraded by past flooding events and provide floodwater storage during major flooding events at the confluence of the Mississippi and Ohio Rivers.

Environmental Research and Geochemical Evaluation of Recent Bottom Sea Sediments North and North –East of Lesvos Island, Greece

An environmental and geochemical investigation of 33 surficial sediments of the continental shelf north and north east of Lesvos Island Greece was undertaken to study the mineralogy and geochemistry of the sediments and understand the distribution and sources of various major and trace elements. Texturally all the sediments contain high amounts of mud and clay indicating a uniform facies at depths between 30m - 300m. The sediments are a mixture of terrigenous components (albite, K-feldspar, muscovite, quartz, illite, amphibole and biogenic components (calcite, Mgcalcite, aragonite). Pyrite and glauconite are ascribed to diagenesis. There are four distinctive groups of elements each of which includes related elements, derived from different natural sources on land or in the marine basin. The first group (Ca, Sr) reflects the biogenous carbonate fraction and is negatively correlated against every other element determined. A second (Si, Al, Fe, Na, K, Ti, Ba and Zr) group reflects the aluminosilicate minerals derived from the alteration of volcanic rocks, and a third group (Mg, Ni, Cr, C and Zn) reflects the aluminosilicate minerals derived from the alteration of ultrabasic rocks (peridotites) and the organic carbon. The group of Fe, Mn, Zn and Y is a diagenetic association reflecting the distribution of these elements with pyrite. The association of Cu with Zn reflects a mineralization control in the sediment area. Finally, La and Ce are associated with the K-bearing minerals, while P is related to K and Fe-finegrained minerals. The concentrations of heavy metals in the sediments are normal comparing to the contents of other AEGEAN SEA sediments and are due to natural lithogenic sources.

Extraterrestrial Metallic Iron in the Lacustrine, Epicontinental and Oceanic Sediments: A Review of Thermomagnetic and Microprobe Analyzes Data

The article represents an overview and generalization of the microprobe and thermomagnetic data on the distribution, content and composition of metallic iron in Pleistocene lacustrine sediments of the Darhad Basin, northern Mongolia, in the Upper Miocene sediments of Lake Baikal, epicontinental sediments of Miocene-Late Jurassic, and Early Cambrian ages in different regions of North Eurasia and in Miocene-Late Jurassic oceanic sediments of North- Western Atlantic. Iron particles percentage varies from ~10-5 to 0.05%, their distribution is bimodal with the distinct zero mode, and the accumulation of iron particles is inversely linked with the rate of sedimentation. Pyrite and pyrrhotite are widespread in the studied sediments, and the distribution of metallic iron does not depend on the presence of pyrite (i.e., on redox conditions). The variations in the Curie temperature of iron from 700°C up to 780°C. The nickel admixture in native iron forms three groups, 1) pure iron (main part of particles), 2) iron with mode 5-6% Ni (kamacite), and 3) Fe-Ni alloy with mode 50% Ni (rare), were found in all studied sections. The global pattern of the distribution and composition of the iron particles clearly indicates that their origin is associated with interplanetary cosmic dust. At the same time, the particles of Fe-Ni alloy are very rare, and their concentration does not correlate with the content of other iron particles. Most likely, the particles of Fe-Ni alloy are mainly due to impact events. Correlation between the concentrations of iron particles and terrestrial minerals (magnetite) is absent as a rule. Such correlation (r=0.3-0.7) testifies the redeposition of iron particles.

Seismic evidence of continental margin influence on the NinetyEast Ridge in the Bay of Bengal

AbstractThe NinetyEast Ridge (NER), one of the most enigmatic features in the Indian Ocean, is covered by thick Bengal Fan sediment north of 9°N. We present seismic reflection data on the eastern flank of the NER, at 10°N, that show the presence of 4–5 km thick sediments beneath the Bengal Fan sediments. These sediments can be imaged up to 60 km beneath the Andaman fore‐arc accretionary wedge, suggesting that the décollement lies above these sediments. The presence of thick sediments above the northernmost segment of the NER suggests that this segment was close to a continental margin during its emplacement. We propose that these sediments were deposited soon after the breakup of India and Antarctica, between 130 and 100 Ma, and might act as source rocks for oil and gas generation beneath recent Bengal Fan sediments. Furthermore, subducting thick sediments can significantly change the seismogenic behavior of the Andaman subduction zone.

Provenance of late Palaeozoic terrestrial sediments on the northern flank of the Mid North Sea High: detrital zircon geochronology and rutile geochemical constraints

Abstract Zircon U–Pb and rutile trace element data are used to investigate the provenance of late Devonian to early Permian terrestrial sandstones in the Embla and Flora oil fields on the north flank of the Mid North Sea High, central North Sea. Two Old Red Sandstone samples (ORS 1) are dominated by 1.2–0.9 Ga Grenvillian zircons and low- to medium-grade rutile, with sparse Cambro-Ordovician Caledonian zircons (2–4%) and high-grade rutiles (0–5%). The samples are interpreted as recycled metasediments from the Scottish Caledonides. Two other Old Red Sandstone samples (ORS 2) contain a high proportion of Caledonian, mainly Silurian zircons (15–19%) and high-grade rutiles (15–18%); we propose that these components are traceable to the Krummedal sequence on East Greenland (and related sediments). We interpret the data to reflect a temporal evolution of the regional drainage system from northwestern to northeastern sources, with high-grade detritus reaching the Mid North Sea High in the Famennian–early Carboniferous. A late Carboniferous and an early Permian sandstone yielded zircon and rutile signatures compatible with recycling of Palaeozoic sediments north of southernmost Scotland, probably reflecting inversion tectonics. Recycling of Mesoproterozoic to Palaeozoic sediments is thus a prominent feature of the studied late Palaeozoic sandstones. Supplementary material: Electron microprobe data from rutile trace element analyses, additional rutile temperature plots and zircon LA-ICPMS U–Pb data are available at http://www.geolsoc.org.uk/SUP18617 .

Geochemical and Isotopic Signatures of Surficial Sediments from the Western Continental Shelf of India: Inferring Provenance, Weathering, and the Nature of Organic Matter

Abstract Bottom sediments from thirteen transects sampled mainly at depth contours of 30, 100, and 200 m along the western continental margin of India, falling in two offshore sectors from Dwaraka to Goa and Cape Comorin to Goa, were analyzed for calcium carbonate, major elements in silicate fraction, trace and rare earth elements in the bulk fraction, and carbon and nitrogen isotopes in organic matter to understand the provenance of sediments, weathering patterns in the source areas, and nature of organic matter. Major elements such as Si, Ti, Mg, and discrimination plots involving alkalies and silica have shown a distinct north–south provinciality, with the source signatures pointing at Deccan basalt for sediments in the north (from Dwaraka to Goa) and gneisses and granulites of South India in the south. Shale-normalized REE patterns and REE content suggest additional local sources mainly in the southwest coast of India. Degree of alteration determined using Chemical Index of Alteration (CIA), Plagioclase Index of Alteration (PIA), and A-CN-K plots have suggested that the sediments are moderately weathered despite the intense orographic rainfall in the source area. Variability in degree of chemical weathering is seen with the change in provenance. In general, the sediments north of Goa with a provenance of Deccan basalts show a higher chemical weathering index. Corg/N molar ratios are mostly between 10 and 12 (minimum and maximum being 6.9 and 14 respectively), which are closer to values for marine organic matter. This is corroborated by marine δ13C values (−18.2 to −21.6‰). While they broadly fall within the marine values, heavier values are seen in northern transects off Porbandar and Dwaraka, where the sediments have a provenance different from those in the south. This could be due to a higher contribution from C4-type vegetation in the north, consistent with heavier δ13C values in terrestrial plants in source regions. Heavier δ15N values are observed for the northern transects (north of Ratnagiri), which is supported by the intense denitrification in the northern Arabian Sea.

Grimsdalea magnaclavata Germeraad, Hopping & Muller: an enigmatic pollen type from the Neogene of northern South America

Grimsdalea magnaclavata was first described by Germeraad, Hopping and Muller from Miocene and Pliocene deposits of northern South America, specifically Colombia and Venezuela. The specific epithet, ‘magnaclavata', was selected by the authors to draw attention to the distinctive clavate processes of the pollen. A revised taxonomic description is supported by illustrations of fossil specimens from outcrop and well sections that show the range in morphology not previously recorded in the original description; the key difference is the wide variation in process morphology from clavae to clavae with interspersed echinae. Based on the new observations of the pollen morphology we conclude that the records from Cretaceous and Paleogene sediments in North and West Africa are invalid. G. magnaclavata is clearly restricted to northern South America from the Miocene to Pleistocene. The parent plant of G. magnaclavata probably grew in upper coastal plain or around swamps, commonly associated with shrubs and herbaceous savannah plants. The botanical affinity of G. magnaclavata has always been in question. Based on a review of pollen from several palm genera presently extant in northern South America we consider that the nearest living relatives, if indeed G. magnaclavata is an ancient palm, are the genera Mauritia and Mauritiella. The basis for this conclusion is the distinctive foot layer morphology of the processes in the fossil and the modern examples.

Signature of organic matter exported from naturally Fe-fertilised oceanic waters

Biomarker distributions and organic carbon and nitrogen isotopic signatures of organic matter (OM) produced in surface waters around the Crozet Plateau (Southern Ocean) are significantly different between a Fe-fertilised region (north) and a high nutrient low chlorophyll region (HNLC, south). If these OM signatures are exported to and preserved in surface sediments, they could potentially be used as palaeo-proxies for identifying Fe-fertilisation events in the past. Here, we assess the alteration of the OM signature through the water column and at the sediment–water interface by comparing organic signatures in surface waters, sediment traps and surface sediments. Our results suggest that there is significant degradation of OM during transport to the sea floor, which causes reduced fluxes of biomarkers to sediments north and east of the Crozet Plateau. Sterols, alkenones and C27 and C29 12-hydroxymethyl alkanoates, and C28 1,14-diols appear to be less labile than total organic carbon (TOC), except to the north, where alkenones and sterols are more rapidly degraded than TOC. Sedimentary bulk and compound specific δ13C values also reflect surface water productivity patterns, with elevated values occurring in sediments underlying the Fe-fertilised waters. In contrast, δ15N values appear to be strongly biased by degradation and grazing during export and burial. Thus, only some of the differences observed in surface waters between the Fe- fertilised and HNLC areas are exported to deep waters and preserved in the sedimentary record, suggesting that caution is required in the application of these proxies to studies of ocean palaeoproductivity.

Holocene variations in mineral and grain-size composition along the East Greenland glaciated margin (ca 67°–70°N): Local versus long-distance sediment transport

Quantitative X-Ray Diffraction (qXRD) analysis of the <2 mm sediment fraction from surface (sea floor) samples, and marine sediment cores that span the last 10–12 cal ka BP, are used to describe spatial and temporal variations in non-clay mineral compositions for an area between Kangerlussuaq Trough and Scoresby Sund (∼67°–70°N), East Greenland. Bedrock consists primarily of an early Tertiary alkaline complex with high weight% of pyroxene and plagioclase. Farther inland and to the north, the bedrock is dominantly felsic with a high fraction of quartz and potassium feldspars. Principal Component (PC) analysis of the non-clay sediment compositions indicates the importance of quartz and pyroxene as compositional end members, with an abrupt shift from quartz and k-feldspar dominated sediments north of Scoresby Sund to sediments rich in pyroxene and plagioclase feldspars offshore from the early Tertiary basaltic outcrop. Coarse (<2 mm or <1 mm) ice-rafted sediments are largely absent from the trough sediments between ∼8 and 5 cal ka BP, but then increase in the last 4 cal ka BP. Compositional unmixing of the sediments in Grivel Basin and Kangerlussuaq Trough indicate the dominance of local over long distance sediment sources, with pulses of sediment from tidewater glaciers in Kangerlussuaq and Nansen fjords reaching the inner shelf during the Neoglaciation. The change in IRD is more dramatic in the sediment grain-size proxies than in the quartz wt%. Forty to seventy percent of the variance in the quartz records from either side of Denmark Strait is explained by low frequency trends, but the data from the Grivel Basin, East Greenland, are distinctly different, with an approximate 2500 yr periodicity.

Testing Miocene Remagnetization of Bey Dağları: Timing and Amount of Neogene Rotations in SW Turkey

Here we reassess the timing and amount of rotation of the eastern limb of the Aegean orocline, located in SW Turkey. The current model for this orocline involves a 25-30° counterclockwise (CCW) rotation of the Bey Dağları region, which exposes upper Cretaceous to Eocene platform carbonates and lower Miocene flysch deposits. In this model the rotation has to postdate a Miocene remagnetization, which would not exclude non-synchroneity between rotations of the western and eastern limbs of the Aegean orocline. To test this model a detailed palaeomagnetic study was conducted on lower Miocene strata in the Bey Dağları area. Two (composite) sections were sampled near Korkuteli and Doğantaş, spanning the lower Miocene foreland basin stratigraphy from the Aquitanian unconformity with the Bey Dağları limestones to the uppermost Burdigalian-lowermost Langhian, and a wide array of palaeomagnetic analyses were obtained. The natural remanent magnetization (NRM) in the Aquitanian limestones and Burdigalian blue clays resides dominantly in magnetite with minor greigite and haematite. A positive reversals test, a correlation of obtained polarity patterns to the geomagnetic polarity timescale, showing significant compaction following acquisition of the NRM, a scatter in NRM directions that can be confidently attributed to palaeosecular variation and a positive recently-proposed end-member model test of the acquisition curves of isothermal remanent magnetization (IRM) all show that the Miocene sediments on the Bey Dağları platform have not been remagnetized. Our new results, combined with a partial reassessment of existing data, imply that the Bey Dağları region underwent no rotation between the late Cretaceous and late Burdigalian, and 20° counterclockwise rotation between 16 and 5 Ma, i.e. during the middle to late Miocene and prior to deposition of previously reported non-rotated Pliocene sediments north of Antalya. The two limbs of the Aegean orocline thus rotated simultaneously: our new age constraints of 16-5 Ma in the east, compare with (largely) 15-8 Ma in the west, as published previously. The rotation of the Bey Dağları was probably bounded in the south at the plate boundary with Africa, and in the east by the Aksu thrust and Kırkkavak dextral strike-slip fault, which together partitioned dextral transpression induced by the rotating block. Accommodation of the western Anatolian rotations to the north and west of the Bey Dağları will be the subject of a future publication.

Catastrophic middle Pleistocene jökulhlaups in the upper Susquehanna River: Distinctive landforms from breakout floods in the central Appalachians

Widespread till and moraines record excursions of middle-Pleistocene ice that flowed up-slope into several watersheds of the Valley and Ridge Province along the West Branch of the Susquehanna River. A unique landform assemblage was created by ice-damming and jökulhlaups emanating from high gradient mountain watersheds. This combination of topography formed by multiple eastward-plunging anticlinal ridges, and the upvalley advance of glaciers resulted in an ideal geomorphic condition for the formation of temporary ice-dammed lakes. Extensive low gradient (1°–2° slope) gravel surfaces dominate the mountain front geomorphology in this region and defy simple explanation. The geomorphic circumstances that occurred in tributaries to the West Branch Susquehanna River during middle Pleistocene glaciation are extremely rare and may be unique in the world. Failure of ice dams released sediment-rich water from lakes, entraining cobbles and boulders, and depositing them in elongated debris fans extending up to 9 km downstream from their mountain-front breakout points. Poorly developed imbrication is rare, but occasionally present in matrix-supported sediments resembling debris flow deposits. Clast weathering and soils are consistent with a middle Pleistocene age for the most recent flows, circa the 880-ka paleomagnetic date for glacial lake sediments north of the region on the West Branch Susquehanna River. Post-glacial stream incision has focused along the margins of fan surfaces, resulting in topographic inversion, leaving bouldery jökulhlaup surfaces up to 15 m above Holocene channels. Because of their coarse nature and high water tables, jökulhlaup surfaces are generally forested in contrast to agricultural land use in the valleys and, thus, are readily apparent from orbital imagery.

Heavy Metals Contents on Beach Sediments North and South of Sohar Industrial Area, Oman

total of 63 surface sediment samples from three sites: Harmul north of Sohar industrial area, Majees south of Sohar industrial area and Zafaran nine kilometers south of Majees were collected in November 2005. They were analyzed for 11 heavy metals including: Vanadium (V), chromium (Cr), manganese (Mn), nickel (Ni), copper (Cu), selenium (Se), mercury (Hg), cadmium (Cd), lead (Pb), zinc (Zn) and arsenic (As) using microwave digestion followed by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The concentrations of chromium, manganese and vanadium were higher in Harmul than Majees and Zafaran. Arsenic concentration was generally low except in some stations. The results revealed that heavy metals concentrations in these sites are not alarming.