Organic and inorganic geochemistry of some coastal plain rivers of the southeastern United States

In a comprehensive study of the distribution of organic and inorganic constituents in natural waters, the chemical compositions of several rivers flowing through the Coastal Plain of southeast Georgia (the Satilla River, in particular) have been investigated. These streams are generally characterized by low suspended load, low ionic strength, low pH values, and a predominance of organic over inorganic constituents. The dominance of sodium and chloride among inorganic ions indicates that rainfall is a major factor in determining the distribution of major elements in these waters. The low pH values and the relatively high concentrations of iron and aluminum appear to result from the high concentrations of organic matter. Chemical analysis (total acidity, carboxyl groups, amino acid residues, and CHN analysis) and spectroscopic analysis (i.r. and NMR) indicate that river water organic matter is chemically similar to soil fulvic acids.The dominance of organic matter over inorganic constituents and the resultant low pH values of these waters are in direct contrast with the chemical compositions of most of the rivers of the world which have been previously studied. Many large tributaries draining from the low relief tropical basins of the Amazon and other tropical rivers are expected to show similar characteristics; however, none of these has been studied extensively.     

Late Middle Pleistocene deposits at Norton Farm on the West Sussex coastal plain,southern England

The coastal plain of West Sussex, southern England, is internationally important because of the sequence of discrete high‐sea‐level events preserved at various elevations across it. New evidence is presented from a site at Norton Farm, near Chichester, on the Lower Coastal Plain, where Pleistocene marine sands, fining upwards into silts, occur between 5.3 m and 9.1 m OD. The sequence reflects a regressive tendency at the transition from an interglacial to a cold stage. The marine sands have yielded foraminifera, ostracods and molluscs that indicate a declining marine influence through the sequence, culminating in a tidal mudflat, strongly weathered in places. Cool‐climate foraminifera (including Elphidium clavatum, Cassidulina reniformis and Elphidium albiumbilicatum) and ostracods have been recovered from the marine sands. Some species with an apparent preference for warmer water conditions, however, are also present. Freshwater taxa washed into the terminal marine sediments include some cold climate indicators, such as Pisidium stewarti and P. obtusale lapponicum. Additional evidence for cool climatic conditions during the deposition of the upper part of the marine sequence is provided by the lack of tree taxa in the pollen record and by features of the micromorphology. The marine sediments probably began accumulating during OIS 7, a conclusion based on their elevation, on amino acid ratios from shells, but especially on vertebrate evidence, particularly the presence of a small form of horse, together with a large, distinctive, form of northern vole (Microtus oeconomus). The occurrence of cool climate indicators in these marine sediments may demonstrate a lag between the climatic deterioration and the expected glacio‐eustatic fall in relative sea‐level. This evidence appears to support the conclusions drawn from the study of coral terraces in Barbados. Such a scenario would provide the conditions necessary for the emplacement of the large erratic boulders reported from the Lower Coastal Plain of West Sussex. Copyright © 2000 John Wiley & Sons, Ltd.     

Geochemistry of shallow ground water in coastal plain environments in the southeastern United States: implications for aquifer susceptibility

Ground-water chemistry data from coastal plain environments have been examined to determine the geochemical conditions and processes that occur in these areas and assess their implications for aquifer susceptibility. Two distinct geochemical environments were studied to represent a range of conditions: an inner coastal plain setting having more well-drained soils and lower organic carbon (C) content and an outer coastal plain environment that has more poorly drained soils and high organic C content. Higher concentrations of most major ions and dissolved inorganic and organic C in the outer coastal plain setting indicate a greater degree of mineral dissolution and organic matter oxidation. Accordingly, outer coastal plain waters are more reducing than inner coastal plain waters. Low dissolved oxygen (O₂) and nitrate (NO₃⁻) concentrations and high iron (Fe) concentrations indicate that ferric iron (Fe (III)) is an important electron acceptor in this setting, while dissolved O₂ is the most common terminal electron acceptor in the inner coastal plain setting.The presence of a wide range of redox conditions in the shallow aquifer system examined here underscores the importance of providing a detailed geochemical characterization of ground water when assessing the intrinsic susceptibility of coastal plain settings. The greater prevalence of aerobic conditions in the inner coastal plain setting makes this region more susceptible to contamination by constituents that are more stable under these conditions and is consistent with the significantly (p<0.05) higher concentrations of NO₃⁻ found in this setting. Herbicides and their transformation products were frequently detected (36% of wells sampled), however concentrations were typically low (<0.1 μg/L). Shallow water table depths often found in coastal plain settings may result in an increased risk of the detection of pesticides (e.g., alachlor) that degrade rapidly in the unsaturated zone.     

Pleistocene marine deposits in the coastal areas of Kola Peninsula (Russia)

On the basis of field data, datings from both electron spin resonance – and optically stimulated luminescence, and micro- and macrofauna, in addition to presence of diatoms, three Late Pleistocene marine units have been identified in the coastal areas of the Kola Peninsula. The stratigraphically lowest sequence is correlated to the Ponoi Beds and the Boreal transgression, attributed to the marine isotope stages (MIS) 5e to 5d in the White Sea depression and to MIS 5e to 5c in the Barents Sea. Thermophilic fauna and diatoms indicate normal water salinity and a water temperature above zero. The second marine unit, referred as the Strel'na Beds, can be correlated with the Early Weischselian transgression, termed the Belomorian transgression. With low water salinity and a water temperature similar or colder than the present times, Belomorian transgressions are reliably detected in the White Sea and are not clearly found in the Barents Sea. The results obtained from the sediments of the Ponoi and Strel'na Beds indicate a continuously existing marine reservoir from 130 to 80–70 ka ago (entire MIS 5) in the White Sea depression. The early Middle Weichselian Barents–Kara ice-sheet invasion and its recession might have caused the glacioeustatic Middle Weichselian (MIS 3) transgression, and the third Late Pleistocene marine sequence has been deposited in the regressing shallow cold sea with less saline waters. The results help in the understanding of the history of Late Quaternary ice sheets in North Eurasia and provide evidence for the debatable Early and Middle Weichselian marine events.     

Extreme sea levels,coastal flooding and climate change with a focus on Atlantic Canada

Estimation of the probability distribution of extreme sea levels, for the present time and the next century, is discussed. Two approaches are described and their strengths and weaknesses are compared. The first approach is based on dynamics and uses a storm surge model forced by tides, winds and air pressure fields. The second approach is based on the statistical analysis of observed hourly sea level records using a new first-order Markov process that can capture non-Gaussian characteristics (such as skewness) in the non-tidal component of the observed sea level record. It is shown that both approaches can provide good estimates of present day flooding probabilities for regions with relatively strong tides. The limitations of both approaches in terms of assessing the effect of global sea level rise, glacial-isostatic adjustment of the land, and changes in the frequency and severity of storms and hurricanes, are illustrated using recent results for the Northwest Atlantic. Some sensitivity studies are carried out to transform uncertainty in climate change projections into uncertainties in the probability of coastal flooding.     

Land subsidence and sea level rise on the Atlantic Coastal Plain of the United States

Land subsidence due to decline in head in confined aquifers, related to municipal and industrial water pumpage, is widespread in the Atlantic Coastal Plain. Although not a major engineering problem, subsidence greatly complicates adjustment of precise leveling and distorts prediction of future sea-level rise. When preconsolidation stress equivalent to about 20 m of head decline is exceeded compaction of fine-grained sediments of the aquifer system begins, and continues until a new head equilibrium is attained between fine and coarse units. The ratio subsidence/head decline is quite consistent, ranging from 0.0064 in southeastern Virginia to 0.0018 at Dover, Delaware and Atlantic City, New Jersey. Higher values are related to the occurrence of montmorillonite as the predominant clay mineral present. Review of tide gauge records indicates that gauges not affected by land subsidence or other local secular effects have been sinking relative to sea level since 1940 at rates averaging about 2.5 mm/yr, of which 0.6 mm/yr is ascribed to glacio-isostatic adjustment to unloading of North America resulting from melting of late Pleistocene glaciers, and about 0.9 mm/yr is ascribed to steric sea-level rise related to ocean warming. The residual 1 mm/yr of relative sea-level rise is not well understood, but may be related to regional tectonic subsidence of the Atlantic coast.     

Coal deposits of the United States

The coal fields of the Unites States can be divided into six major provinces. The Appalachian and Interior Provinces contain dominantly bituminous coal in strata of Pennsylvanian age. The coal seams are relatively thin and are mined both by surface and underground methods. Sulfyur content is low to moderate in the Appalachian Province, generally high in the Interior province. The Gulf Coastal Plain Province, in Texas and neighboring states, contains lignite of Eocene age. The seams are 3–25 ft (0.9–7.5 m) thick and are minded in large open pits. The Northern Great Plains Province has lignite and subbituminous coal of Cretaceous, Paleocene and Eocene age. The coal, largely very low in sulfur, occurs in beds up to 100 ft (30 m) thick and is strip-mined. The Rocky Mountain Province contains a great variety of coal deposits in numerous separate intermontane basins. Most of it is low-sulfur subbituminous to bituminous coal iof Creatceous and early Tertiary age. The seams range from a few feet to over 100 ft (30 m) thick. Strip-mining dominates but underground mines are important in Utah and Colorado. The Pacific Coast Province, which includes Alaska, contains enormous cola resources but has seen little mining. The coal is highly diverse in physical character and geologic setting.     

Possible ice-rafted erratics in late Early to early Middle Pleistocene shallow marine and coastal deposits in northeast Norfolk, UK

Erratic clasts with a mass of up to 15 kg are described from preglacial shallow marine and coastal deposits (Wroxham Crag Formation) in northeast Norfolk. Detailed examination of their petrology has enabled them to be provenanced to northern Britain and southern Norway. Their clustered occurrence in coastal sediments in Norfolk is believed to be the product of ice-rafting from glacier incursions into the North Sea from eastern Scotland and southern Norway, and their subsequent grounding and melting within coastal areas of what is now north Norfolk. The precise timing of these restricted glaciations is difficult to determine. However, the relationship of the erratics to the biostratigraphic record and the first major expansion of ice into the North Sea suggest these events occurred during at least one glaciation between the late Early Pleistocene and early Middle Pleistocene (c. 1.1–0.6 Ma). In contrast to the late Middle (Anglian) and Late Pleistocene (Last Glacial Maximum) glaciations, where the North Sea was largely devoid of extensive marine conditions, the presence of far-travelled ice-rafted materials implies that earlier cold stage sea-levels were considerably higher.     

Beach deposits of MIS 5e high sea stand as indicators for tectonic stability of the Carmel coastal plain,Israel

Ten beach deposits, mainly beachrock, on the Carmel coastal plain, northern Israel, are discussed. Six are reported for the first time. The deposits are situated within or close to the following seasonal stream (locally termed Nahal) channels: Nahal Ahuza, Amiram, Ovadia, Galim, Megadim, Bir Ibdawiya, Me’arot and Kebara. The morphology and lithology of most of the deposits are similar: their uppermost altitude varies from 0 to 9 m above the present sea level. Most of the deposits are composed mainly of fine quartz sand and marine mollusk shells carbonate cemented. The dominant mollusk families are Glycymerididae, Cardiidae and Donacidae. Most of the beach deposits are situated between cemented aeolian sandstones (locally termed kurkar) layers on the Carmel coast ridge. In the Nahal Ahuza deposit, a marine gastropod Lentigo latus, an index fossil for the MIS 5e high sea stand in the Mediterranean area was discovered.According to lithology and chronostratigraphy, the presence of Lentigo latus, Th/U, AAR and RTL dating and flint artifacts, the beach deposits were related to the Last Interglacial maximum about 125 ka BP, i.e. the MIS 5e high sea stand. These beach deposits are used to identify the palaeo sea levels and coastlines and to study the tectonics along the Carmel coastal plain. By comparing the elevations and characteristics of the beach deposits to known MIS 5e deposits elsewhere, and by analyzing archaeological data, it is concluded that during the last 125 ka, the maximum possible vertical displacement was less than 48 mm/ka, and the Carmel coastal plain was relatively tectonically stable.     

Pleistocene succession of the central interior United States

The Quaternary of the continental interior of the United States is characterized by deposits from glacial ice, with associated outwash and eolian deposits, and by alluvial deposits produced by the same climatic pulses. Erosional incision of valleys occurred early in the glacial pulse, outwash deposition during the waning phase of the pulse, and soil formation during times of relative stability between the glacial pulses. These features of deposition, erosion, and soil formation are presented in a series of curves. One way the marine record could be correlated with that of the continental interior is to compare and match the physical records of both environments.     

New U/Th ages for Pleistocene megafauna deposits of southeastern Queensland,Australia

Arguments over the extinction of Pleistocene megafauna have become particularly polarised in recent years. Causes for the extinctions are widely debated with climate change, human hunting and/or habitat modification, or a combination of those factors, being the dominant hypotheses. However, a lack of a spatially constrained chronology for many megafauna renders most hypotheses difficult to test. Here, we present several new U/Th dates for a series of previously undated, megafauna-bearing localities from southeastern Queensland, Australia. The sites were previously used to argue for or against various megafauna extinction hypotheses, and are the type localities for two now-extinct Pleistocene marsupials (including the giant koala, Phascolarctos stirtoni). The new dating allows the deposits to be placed in a spatially- and temporally constrained context relevant to the understanding of Australian megafaunal extinctions. The results indicate that The Joint (Texas Caves) megafaunal assemblage is middle Pleistocene or older (>292 ky); the Cement Mills (Gore) megafaunal assemblage is late Pleistocene or older (>53 ky); and the Russenden Cave Bone Chamber (Texas Caves) megafaunal assemblage is late Pleistocene (～55 ky). Importantly, the new results broadly show that the sites date prior to the hypothesised megafaunal extinction ‘window’ (i.e., ～30–50 ky), and therefore, cannot be used to argue exclusively for or against human/climate change extinction models, without first exploring their palaeoecological significance on wider temporal and spatial scales.     

Lithofacial complexes of quaternary deposits in the central and southeastern baltic sea

Geological and seismic profiling data (more than 25000 km of seismic profiles and about 1000 sediment sampling stations) collected during the last 30 yr by research vessels of the Shirshov Institute of Oceanology, Russian Academy of Sciences are summarized. Seismic records are directly correlated with sediment cores. The distribution map (scale 1 : 500000) of Quaternary lithofacial complexes corresponding to certain stages of the Baltic Sea evolution is compiled. The following four complexes are distinguished (from the base to the top): (I) moraine, with maximum thicknesses 60 and 170 m in valleys and ridges respectively: (II) varved clay of periglacial basins and from the Baltic Ice Lake (BIL), up to 25 m thick in depressions; (III) lacustrinemarine homogeneous clay with a thickness up to 4–8 m in depressions; (IV) marine sediments (mud, aleurite, coarse-grained deposits) accumulated in environments with intense bottom currents activity (thickness 2–4 m in the Gotland Basin, 4–6 m in the Gdansk Basin, and 10–20 m in fans and prodeltas). The Quaternary sequence is cut through by inherited valleys, where the thickest Holocene sediments are noted. Today, these valleys serve as routes of sediment transport to slope bases and central parts of basins. Outblows of deep gas (through faults and fractures) and diagenetic gas (from sediments) to the bottom surface also occur in the valleys. Sedimentation rates are higher in the Gdansk Basin (up to 100–120 cm/ka). Thick sand, aleurite, and mud bodies are accumulated here (about 15–20 m in the Visla River prodelta). The sedimentation rate is slower in the Gotland Basin (up to 50–60 cm/ka), where thin (2–4 m) sections of more fine-grained mud occur     

Pleistocene sea-level fluctuations and human evolution on the southern coastal plain of South Africa

Humans evolved in Africa, but where and how remain unclear. Here it is proposed that the southern coastal plain (SCP) of South Africa may have served as a geographical point of origin through periodic expansion and contraction (isolation) in response to glacial/interglacial changes in sea level and climate. During Pleistocene interglacial highstands when sea level was above ?75 m human populations were isolated for periods of 360–3400 25-yr generations on the SCP by the rugged mountains of the Cape Fold Belt, climate and vegetation barriers. The SCP expands five-fold as sea level falls from ?75 to ?120 m during glacial maxima to form a continuous, unobstructed coastal plain accessible to the interior. An expanded and wet glacial SCP may have served as a refuge to humans and large migratory herds and resulted in the mixing of previously isolated groups. The expansive glacial SCP habitat abruptly contracts, by as much as one-third in 300 yr, during the rapid rise in sea level associated with glacial terminations. Rapid flooding may have increased population density and competition on the SCP to select for humans who expanded their diet to include marine resources or hunted large animals. Successful adaptations developed on an isolated SCP are predicted to widely disperse during glacial terminations when the SCP rapidly contracts or during the initial opening of the SCP in the transition to glacial maxima. The hypothesis that periodic expansion and contraction of the SCP, as well as the coastal plain of North Africa, contributed to the stepwise origin of our species over the last 800 thousand years (kyr) is evaluated by comparing the archeological, DNA and sea-level records. These records generally support the hypothesis, but more complete and well dated records are required to resolve the extent to which sea-level fluctuations influenced the complex history of human evolution.     

Faults and other shears in bedded Pleistocene deposits on the Wirral, United Kingdom

Normal and reverse faults, thrusts and shears with traceable lengths rarely over 0.35 m and throws of up to 0.014 m are locally developed within a series of bedded glacial meltwater deposits. They are believed to have originated during undrained loading of those deposits by an overlying flow till of late Devensian age. Local disturbance of beds by injection of fluid fine sands indicates past generation of high porcwater pressures.     

Land–sea correlation of Middle Pleistocene temperate sub-stages using high-precision uranium-series dating of tufa deposits from southern England

High-precision U-series dating allows a direct correlation to be made between terrestrial records of the penultimate interglacial (Marine Oxygen Isotope Stage 7 (MIS 7)) in Britain and sub-stage climate forcing in the marine oxygen isotope sequence. U-series ages of surficial tufa deposits are of sufficient precision to correlate discrete episodes of temperate conditions with individual warm sub-stages within MIS 7. Furthermore, detailed biostratigraphy allows periods of faunal turnover to be correlated with cold climates and lowered sea level. Ecological and environmental conditions in Britain during MIS 7 are therefore driven by the short-lived, sub-stage climate forcing that is observable in the marine isotope record. It is clear that interglacial climates are highly dynamic, producing multiple climatic optima and a diverse range of environments within single warm episodes. Consequently sub-stage records of climate forcing are crucial frameworks for reconstructing terrestrial records of environmental change.     

Comparison of amino acid racemization geochronometry with lithostratigraphy, biostratigraphy, uranium-series coral dating, and magnetostratigraphy in the Atlantic Coastal Plain of the southeastern United States

The results of an integrated study comprising litho- and biostratigraphic investigations, uranium-series coral dating, amino acid racemization in molluscs, and paleomagnetic measurements are compared to ascertain relative and absolute ages of Pleistocene deposits of the Atlantic Coastal Plain in North and South Carolina. Four depositional events are inferred for South Carolina and two for North Carolina by all methods. The data suggest that there are four Pleistocene units containing corals that have been dated at about 100,000 yr, 200,000 yr, 450,000 yr, and over 1,000,000 yr. Some conflicts exist between the different methods regarding the correlation of the younger of these depositional events between Charleston and Myrtle Beach. Lack of good uranium-series dates for the younger material at Myrtle Beach makes the correlation with the deposits at Charleston more difficult.     

Geochemical behavior of Pt and Pd in coastal marine sediments,southeastern margin of the Japan Sea

Eighty-one argillaceous marine sediments collected from the southeastern coastal margin of the Japan Sea were analyzed for Pt and Pd by atomic absorption spectrometry using a graphite furnace atomizer after solvent extraction separation. The average Pt (1.2 ± 0.5 ppb) and Pd(1.6 ± 0.9 ppb) contents are generally similar to those of the published crustal abundances. The Pt or Pd is generally enriched in the fine sediment fraction, and positively correlated with Cu, Pb and water depth. The inverse correlation between the Pt or Pd content and redox potential of the sediment suggests that significant amounts of Pt and Pd are supplied in their dissolved forms, and reduced to their metallic states. It is concluded that the Pt and Pd distributions in the coastal marine sediments are controlled by the geological characteristics of the studied area, grain size and redox potential of sediments, water depths, and dissolved O₂ concentration of sea water.     

Radiolarians and stratigraphy of Cenomanian-Coniacian deposits in the Crimean and West Sakhalin Mountains, Pt. 1: Biostratigraphic subdivision and correlation

Radiolarian biostratigraphy suggested in this work for the Cenomanian-Coniacian deposits in the Crimean and West Sakhalin Mountains is enhanced to be of a higher resolution. The Cenomanian-Coniacian succession of the West Sakhalin Mountains is subdivided into nine instead of five biostratigraphic units formerly known in this region. Deposits of the Crimean Mountains are subdivided based on radiolarians within the lower Cenomanian-lower Coniacian stratigraphic interval (the original biostratigraphic chart corresponded here to the upper Cenomanian-middle Turonian interval only). The established biostratigraphic subdivisions are correlated with those of the Tethyan and Pacific scales.