Sediments Of Quaternary Age Research Articles

Suitability of the Lower Zab River Sediments for Concrete Works / Southwest of Kirkuk - Northern Iraq

An Engineering study was carried out for five stations in the Lower Zab basin, southwest of Kirkuk, to determine the viability of the Quaternary age sediments for concrete works. The geotechnical evaluation results included that the coarse aggregate's grain size analysis is identical to the gradient class (63.0 mm) according to the [1] classification. As for the gradation of fine aggregate for the sediments of the study area, the results of the granular gradient of the samples after matching them with the limits of AASHTO specification showed that they are identical to the specification with slight differences on some sieves. The elongation and flatness tests showed that the highest percentage of the longitudinal shape is (19.2%) and flat-shaped particles is (28.8%), within permissible limits according to British standard [2], the specific gravity for coarse aggregate was between (2.60 - 2.64) and saturated specific gravity (2.61 - 2.65), and the values of specific weight for fine soil ranged from (2.72 - 2.64) which is suitable for use in concrete works. The results of the laboratory test of the durability tests - The Los Angeles test for the samples showed that the highest percentage for weight loss was (20%), which is suitable for use in the concrete according to the Iraqi standard [3], the results of the laboratory test for stability showed that the percentage of weight loss for coarse aggregate (gravel) by the effect of sodium sulfate solution and for the number of 5 cycles of the samples ranged between (8.3% - 4.1%), which is valid for use in concrete works according to the American specification [4]. The results of the resistance tests - the point load test for stations (S1, S3, S4) within the classification range of very strong - extremely strong, and the two stations (S2, S5) within the class strong - very strong - extremely strong compared to the classification of [5], and they are good for concrete works. It was found from the results of the chemical tests the gypsum content, organic matter content, Total soluble salts, and the sulfate content of the samples of the study area are suitable to for concrete works according to British Standard [6], which is suitable for concrete works, testing the compressive strength of concrete cubes ranged between (24.93 - 18.22 MPa) for age seven days and ranged between (33.02 - 29.76 MPa) for 28 days for reference mixture, Which is (4:2:1 by weight). According to the Iraqi standard specification [7], the compressive strength values of the samples are suitable for regular unreinforced concrete, and in comparison with [8] classification, it was apparent that the concrete produced is of moderate endurance. And suitable for concrete works According to [9].

Trends and Composition—A Sedimentological-Chemical-Mineralogical Approach to Constrain the Origin of Quaternary Deposits and Landforms—From a Review to a Manual

In this study, six basic Quaternary landform series (LFS) and their sedimentary deposits (LFS1 aeolian, LFS 2.1 to 2.2 mass wasting, LFS 3 cryogenic-glacial, LFS 4.1 to 4.6 fluvial, LFS 5.1 to 5.2 coastal-marine, LFS 6.1 to 6.3 lacustrine) are subdivided into subtypes and examined with regard to their sedimentological parameters and their mineralogical and chemical compositions. Emphasis is placed on the textural (related to transport and deposition), compositional (sediment load/weight, Eh and pH) and geodynamic maturity of the sedimentary deposits which are influenced by the parent lithology and bedrock tectonic and by the climate during the last 2 Ma. To constrain the development of the LFS and their sediments, composite trend-line diagrams are designed combining sedimentological (x-axis) and chemical/mineralogical dataset (y-axis): (1) sorting vs. heavy mineral content; (2) sphericity of grains vs. silica/carbonate contents; and (3) median vs. Ti/Fe ratios. In addition, the x-y plots showing the log SiO2/Al2O3 vs. log Na2O/K2O are amended by a dataset of the three most common clay minerals, i.e., kaolinite-, mica-, and smectite-group clay minerals. Such joint sedimentological-chemical-mineralogical investigations focused on the depositional environment of unconsolidated clastic sediments of Quaternary age can be used to describe the economic geology and environmental geology of mineral deposits in the pre-Quaternary sedimentary series according to the phrase: “The Present is the key to the Past”. Both trend diagrams and compositional x-y plots can contribute to constraining the development of the full transect of landform series from the fluvial incision and slope retreat to reef islands fringing the coastal zone towards the open sea as far as they are built up of clastic sedimentary deposits enriched in siliceous and/or carbonate minerals. Climate zonation and crustal maturity are the exogenous and endogenous “drivers”, as can be deduced from the compositional (mineralogy and chemistry) and physical (transport and deposition) variations observed in the Quaternary sediments. The current study bridges the gap between a review only based on literature and a hybrid manual generated by practical field studies devoted to applied geosciences in economic and environmental geology (“E & E issue”).

Calcretes from the Quaternary alluvial deposit of Purna basin, central India: Lithological and climatic controls

The Purna alluvial basin of central India, infilled largely with areno-argillaceous sediments of Quaternary age, is also marked by occurrences of both pedogenic and non pedogenic calcretes of diverse shape and size. The previous includes nodular, laminar, hardpan and root calcretes along with rhizolith balls and rhizospheres, whereas non pedogenic type is represented by groundwater calcretes. These calcretes have been investigated for their morphological details, lithological associations in both vertical and lateral profiles of the alluvial deposit and paleoclimatic reconstructions. This study shows that the area under investigation has undergone through subtropical, arid and semiarid climatic conditions having low to medium humidity, high rainfall and evaporation that favored formation of various types of calcretes. Nodular calcretes, the most dominant morphotype, are preserved in a wide spectrum of lithology and fluvio-lacustrine environment. To some extent, their formation is controlled by parent material, irregular rainfall and mild temperature. Rapid accumulation of carbonate material, in and around the plant roots giving rise root calcretes of various shapes and size is a common phenomenon in warm and dry climatic conditions. Both hardpan and groundwater calcretes are formed due to CaCO3 precipitations in humid condition having heavy rainfall. Besides, the later also indicates arid to semiarid conditions facilitating the movement of Ca rich solution in the unconsolidated sediments through capillary action that later deposited calcium carbonate in the voids during wet and dry conditions. Well preserved rhizolith balls and rhizospheres in the palaeosols, constituting together the lower part of succession in almost entire alluvial basin, acts as potential paleoclimatic indicator.

Oligo-Miocene coal in a microtidal environment reworked under Quaternary periglacial conditions (Western Falkland Islands/Isla Gran Malvina) – Coal formation and natural sand processing

The Western Falkland Islands are characterized by landforms and sediments of Quaternary age originating from the interplay of periglacial and marine processes. These have left their imprints on siliciclastic sediments and subbituminous coal, peatland, and podzolic soil. Our depositional study focuses on interpreting a stratigraphic sequence which contains white quartz sand with an interbedded coal seam by using petrography (coal petrography, carbon isotope analysis, sedimentary petrography, clay mineralogy, granulometric, morphometric studies), and geochemistry. The study of the coal-sand couple sheds some light on two contrasting sedimentary geological settings. Firstly, it broadens the knowledge of the regional geology at the southern tip of South America by examining how coal seams may be emplaced in a periglacial-microtidal environment. Secondly, the study is also relevant for applied geology by investigating how sand is processed in a coal-bearing paralic regime. The coal-sand couple evolved during 6 discrete stages. Stage I: The detrital parent material was derived from the Siluro-Carboniferous Gran Malvina Group. Stage II: From the Oligocene through the late Miocene under a warm tropical climate organic matter was accumulated in a paralic environment giving rise to subbituminous coal. Stage III: During the Pleistocene alternating erosion and deposition in a wave-dominated coastal-marine regime gave rise to the build-up of coal interbedded with sand. The hydrodynamic regime reduced the grain size to the level of medium to fine sand and enhanced its sorting coefficient causing the separation of minerals according to their specific gravity (mechanical processing). Stage IV: The coal seam has been reworked by the last glacial progradation. Stage V: Weathering by wind and waterworn sand grains into semispherical to spherical forms and the content of heavy minerals increased along backshore and in dune belt environments. Stage VI: Organic acids derived from the coal promoted chemical leaching and significantly contributed to the decrease of the labile constituents of arenites (feldspar, carbonate minerals, and calcareous tests of faunal remains). Chemical alteration was grinded to a halt by another sea level rise, which gradually destroyed the coal layer. The depositional environment most effective for the processing of sand is located in the microtidal setting. In the meso- to macrotidal hydrodynamic regime the chemical leaching becomes the only efficacious tool to improve the quality of the footwall rocks. Due to the predominance of argillaceous sediments there, the quality of clay is enhanced and kaolin deposits may come into existence.

Late Pliocene-Pleistocene environments and glacial history of the northern North Sea

Based on new geochronological (amino acids and Sr-isotopes) and lithological data combined with analyses of 3D seismic data, the Pliocene-Pleistocene development of the central northern North Sea has been investigated. At the start of the Plio-Pleistocene Transition the study area was dominated by a deltaic, shallow marine or tidal depositional environment with sediments mainly sourced from the west. These sand-rich sediments include green glauconitic grains that belong to the Utsira Sand with a local provenance. Directly above the base Quaternary (R2) a 60 m thick layer of mud-rich sediments of glacimarine origin were deposited at a rate of ∼12 cm/ka between ∼2–1.5 Ma and up to 80 cm/ka between 1.5 and 1.2 Ma possibly reflecting glacial ice advancing to the Norwegian coastline. The high rate of deposition in the Early Pleistocene occurred immediately before the initiation of the Norwegian Channel Ice Stream at ∼1.1 Ma. Following this, a large part of the sediment input from Fennoscandia seems to have been directed away from the study area to the shelf break. At the start of the Mid Pleistocene Transition (MPT), subaerial conditions allowed the formation of a >50 km long fluvial channel across the study area draining water from the east to the south west. The earliest evidence of grounded ice in the investigated area comes from mega scale glacial lineations formed during the MPT, at or just after ∼1.2 Ma. Following this, a regional unconformity (R4) was formed by one or more grounded ice advances across the study area possibly during or directly after the MPT and likely marks the boundary between the Early and Mid Pleistocene glacimarine sediments. The Mid to Late Pleistocene stratigraphy is dominated by glacimarine sediments and tills and is associated with multiple generations of tunnel valleys observed within the seismic data. A high shear strength till containing chalk clasts transported from the west and/or south of the study area was likely deposited during MIS6 and may have been more conducive to tunnel valley formation in comparison to lower shear strength tills deposited by later ice advances. A thick till unit overlain by a sand layer in the study area was deposited by grounded ice during the Last Glacial Maximum and subsequent drainage of an ice dammed lake in the southern North Sea during the last deglaciation (MIS2) of the study area. This study shows that much of the Quaternary age sediments within the northern North Sea were deposited relatively rapidly during short periods of time probably leaving significant hiatuses within the stratigraphic record. This finding has implications for previous studies that use a chronological framework assuming a relatively continuous sedimentation rate and record for the Early Pleistocene within the North Sea.

Hydrological Characterization of Budge Budge and Dum Dum Areas of South and North 24 Parganas Districts, West Bengal Using Geoelectric and Geochemical Methods

Abstract: Integrated geoelectric, geological and geochemical investigations are carried out in Budge Budge and Dum Dum areas of south and north 24 Parganas district for ascertaining the prevailing hydrological condition and aquifer characteristic with chemical qualities of groundwater for drinking and irrigation purposes. The proposed areas are constituted of alluvium and marine sediments of Quaternary age being a part of Gangetic delta. Vertical electrical soundings (VES) of Budge Budge have delineated four to six layers consisting of top soils, the brackish water zone, clay layer, first fresh water zone, another clay layer and the bottom-most(sixth layer) second fresh water bearing zone. The first fresh water zone is located at a depth of 128 m with thickness of 43 m having resistivity range of 32 ohm.m to 37 ohm.m for VES locations BB2 and BB3. The resistivity of the deeper second fresh water bearing zone is varying from 47 ohm.m to 51 ohm.m. The interpreted VES results significantly correspond with the borehole litholog of Budge Budge area. Similar VES results are also obtained for Dum Dum area showing promising potential aquifer zone especially for VES locations DD3 and DD4. A litho-resistivity relation is also determined for the area. Total TDS content of Budge Budge ground water samples are ranging from 720 mg/l to 4400 mg/l and same is ranging from 1012 mg/l to 1930mg/l for Dum Dum ground water samples. According to IS standard, the value of major cations and anions are near to the permissible limit for Dum Dum but same is not observed in Budge Budge for drinking and irrigation purpose excepting location G7. According to Piper trilinear diagram, the ground water in Budge Budge area is sulphate rich type and in Dum Dum it is fresh in nature. Chemically, the groundwater samples from Dum Dum and Budge Budge is classified as (Ca+Mg+Cl+SO4) facies. The geochemical parameters like total hardness (TH), sodium adsorption ratio (SAR), soluble sodium percentage (SSP), Kelly’s ratio (KR), magnesium ratio (MR), residual sodium carbonate (RSC), corrosivity ratio (CR), Gibb’s ratio-I&II (GR-I & GR-II), chloro alkaline indices (CAI-I & CAI-II), permeability index (PI), sea water contamination (SWC) are also determined for better understanding of the quality of groundwater in the above areas.

Geoelectric and Geochemical Studies for Hydrological Characterization of Canning and Adjoining Areas of South 24 Parganas District, West Bengal

Abstract: Integrated geoelectric and geochemical investigation were carried out in the Canning and adjoining areas to assess the prevailing groundwater conditions and chemical quality of groundwater. Geologically, the area is constituted of alluvial sediments of Quaternary age. Vertical electrical soundings (VES) in the area of investigation mostly show six layers consisting of top soil, saline water, clay layer, brackish water, clay layer and fresh-water bearing zone of appreciable thicknesses at depths of 137 to 182 meter at six locations and from 370 to 430 meter for other two locations under confined conditions. The result of VES studies significantly correspond with the borehole litholog and well log data. A litho-resistivity relationship is established for this area of investigation A Fence diagram is constructed to show the spatial variation of the sub-surface lithology and hydrological characteristics. Chemically the ground water is fresh and mixed cation and anion type as revealed from Piper-Trilinear diagram with TDS ranging from 699 to 1547 mg/l. The geochemical parameters like Total hardness (TH), Sodium absorption ratio (SAR), Soluble sodium percentage (SSP), Percentage of sodium (PS), Kelley’s ratio (KR), Residual sodium carbonate (RSC), Corrosivity ratio (CR), Gibbs ratios (GR), Chloro alkaline indices (CAI), Sea water contamination (SWC) are also calculated for examining the quality of groundwater in the area. The depth of occurrences of freshwater bearing ground water zones for drinking and irrigation purposes are occurring at depths from 137 meter to 430 meter in this area.

LATE PLEISTOCENE RODENTS (MAMMALIA: RODENTIA) FROM THE BARANICA CAVE NEAR KNJAZEVAC (EASTERN SERBIA): SYSTEMATICS AND PALAEOECOLOGY

Baranica is a cave in the Balkan mountain range in the eastern part of Serbia. It contains four layers of sediments of Quaternary age. The Upper Pleistocene deposits (layers 2-4) have yielded a rich and diverse assemblage of vertebrate fauna, including fish, amphibians, reptiles, birds, and small and large mammals. In this work, preliminary results of a study of the rodent fauna from the Upper Pleistocene deposits of the Baranica Cave (Knjazevac, eastern Serbia) are presented. The fossil material comes from the 1995 archaeological excavation. The remains of 10 rodent species are described herein: Spermophilus cf. citelloides, Castor fiber , Sicista subtilis , Cricetulus migratorius , Cricetus cricetus , Mesocricetus newtoni , Apodemus ex gr. sylvaticus-flavicollis, Spalax leucodon, Dryomys nitedula, and Muscardinus avellanarius. Along with eight vole species, this makes altogether 18 species of rodents found in this locality. Both layers 2 and 4 (layer 3 is very poor in fossils) have yielded a rodent fauna typical for the cold periods of the Late Pleistocene on the Balkan Peninsula, with a prevalence of open and steppe inhabitants, but some forest dwellers were also present. The assemblages from these layers are similar, but there are some differences in the composition of the fauna, which may indicate a slight shift towards drier conditions. They have also been compared to rodent associations from some Serbian and Bulgarian localities of the same age and their similarities and differences are discussed. SHORT NOTE-NOTA BREVE

Late Quaternary variability of precipitation in Southern California and climatic implications: clay mineral evidence from the Santa Barbara Basin, ODP Site 893

Clay mineral assemblages have been investigated in a sequence of Late Quaternary age sediments (160 ka) from the Santa Barbara Basin off California. These predominantly terrigenous sediments contain an assemblage of clay minerals dominated by smectite mostly derived from discharges of the Santa Clara River, together with illite and kaolinite from adjacent relief. Besides its characteristic clay mineral signature, the Santa Clara River has the largest drainage basin in this region and contributes most of the terrigenous load to the Santa Barbara Basin. Smectite contents of the sediments in the basin may therefore be used as a proxy for precipitation and run-off. Distinct changes in the relative abundance of smectite allow reconstruction of the pattern of precipitation, and its relations with regional environments and global climate. This showed that major intervals of precipitation coincide with local development of pine during glacials, and oak during terminations and interglacials; some expansion of mountain glaciers in the Sierra Nevada, especially when they occur during local minima of insolation; and lacustrine developments in the now arid continental interior of California. Major precipitation intervals started during glacials, and persisted during terminations and early interglacials, associated with a weak California Current and subsequent expansion of warm Pacific surface waters. In detail, major precipitation intervals consist of alternating episodes of higher and lower rainfall modulated by orbital precession, with a significant correlation between episodes of high rainfall and minima in precession, which were times of increased meridional gradients, enhanced poleward heat transfer and northward expansion of tropical waters.

Assessment of barrier potential of sediments for selection of waste disposal sites in the Kathmandu Valley

The Kathmandu Valley is an intramontane basin filled with fluvio-lacustrine sediments of Quaternary age. The deposits of the valley comprise lake sediments that accumulated due to damming of the Bagmati River system during Plio-Pleistocene time as a consequence of rise of the Mahabharat Range. The northern and north-eastern parts of the basin are occupied by coarse sediments mainly micaceous sand and gravel derived from the Sheopuri gneiss, while in the central and southern part of the valley, these occur very fine sediments mostly black carbonaceous clay with lignite and diatomaceous earth at places. The maximum thickness of the sediments as revealed by the deepest drill hole in the valley is about 550 m at the central part. The valley floor has a highly undulating topography with buried ridges of Precambrian basement rocks.
 The Kathmandu Valley with population of around 1.5 million is witnessing rapid urban growth, unplanned development and environmental degradation leading to increased pollution. Consequently, the valley is confronted with major problem of safe disposal of urban waste produced at a scale of 500 tones per day. This is largely due to lack of awareness and realization at planning and decision-making levels about the importance of geo-scientific information in identification of suitable landfill sites for solid waste management. This paper attempts to deal with the waste disposal problem by preparing a geo­scientific map showing the potential areas for selecting proper landfill sites based on assessment of subsurface sediments in combination with other relevant aspects related to waste disposal.
 The assessment of barrier potential of sediments is based on the lithological description of bore holes to a depth of 7 m assuming that clay has a high barrier potential, silty to fine sandy sediments have moderate and sandy to gravelly sediments have low barrier potential. The thickness of low-permeable zone has to be at least 5 m to act as natural barrier against toxic leachate originating from waste to protect the groundwater. The effectiveness of such a barrier against migrating pollutants depends on the ability of this layer to retard or exchange pollutants and fix them into soil complex. This is evaluated by determining the Cation Exchange Capacity (CEC) values of the soil derived from laboratory analysis of samples taken down to 2 m depth. Other important parameters for an estimation of the soil barrier function are percolation rate, soil texture, grain-size and soil depth.
 Using GIS ARC/INFO, a map has been prepared delineating areas of barrier potential in three classes: high, moderate and low. The high barrier potential areas are considered as the most favourable sites for waste disposal, whereas the low barrier potential zones are assessed as the negative areas that should not be considered for selecting waste disposal sites. These three groups in conjunction with other selecting criteria (e.g., infrastructures, settlements, water bodies, cultural heritage sites etc.) are presented on a map at a scale of 1:50000. This map provides a good basis for planners and decision-makers for selecting geo-scientifically viable landfill sites for urban waste management.
 Based on this map, six sites were selected for further investigation by drilling up to 8 m depth. Taikabu of Chetdol (Bhaktapur) turned out to be the most promising site for development of a sanitary landfill for long-term management of urban waste of the Kathmandu Valley.

Formas extraíveis de ferro em solos do estado do Rio de Janeiro

No estado do Rio de Janeiro, destacam-se três feições geomorfológicas: as formações constituídas por rochas do Complexo Cristalino, expostas ou capeadas por seus produtos de alteração; os tabuleiros costeiros, compostos pelos sedimentos da Formação Barreiras, e, por último, as planícies aluvionares, que são formações quaternárias. As diferenças entre os materiais de origem e as classes de relevo e sua influência na formação dos solos têm constituído o tema principal dos estudos de genêse realizados no Rio de Janeiro. Este trabalho teve como objetivo avaliar o comportamento das formas extraíveis de ferro, Feo, Fed e Fes, e as relações entre elas em função do grau de pedogênese dos solos. Para estes solos, as formas de ferro e relações Fed/Fes e Feo/Fed expressaram variações na mineralogia do material de origem, grau de intemperismo dos solos e do material formador, ou classe de drenagem, mais do que a intensidade de pedogênese. Assim, as formas extraíveis de Fe e respectivas relações para avaliar o grau de pedogênese, nos solos do Rio de Janeiro, requerem uma interpretação conjunta das demais propriedades do solo, com ênfase para a morfologia e classes de drenagem.

Vertical Hydrochemical Zonation in a Coastal Section of the Botany Sands Aquifer, Sydney, Australia

Near Sydney, Australia, unconsolidated aeolian and alluvial sediments of Quaternary age form the Botany Sands aquifer and lie unconformably on Triassic-age sandstone (Narrabeen Group). Botany Bay is an inlet of the Pacific Ocean about 10 km south of the city centre. Reclamation of the northern foreshore of Botany Bay commenced in 1979. One impact of this reclamation was to move the saline interface in the aquifer southward.

Use of Combined Air Sparging and Soil Vacuum Extraction (AS/SVE) and Groundwater Recovery and Treatment as Remedial Alternatives for Dissolved DNAPL Recovery: ABSTRACT

Corrective action has been implemented to address a dissolved dense non-aqueous phase liquid (DNAPL) plume in the vicinity of a former waste impoundment at the Paxon Polymer Company facility, located north of Baton Rouge, Louisiana. Assessment activities focused on the characterization of the geologic and hydrologic properties of the sediments underlying the area of investigation and the impact of the dissolved DNAPL plume to the soils and groundwater. Geologic characterization revealed that the facility is underlain by Quaternary age sediments consisting of mixtures of fine-grained sands, silt, and clay. Two hydrologic units were identified within the shallow sediments which are referred to as the Upper Permeable Zone and Second Permeable Zone. The investigation focused on the impacted soils and groundwater of the Upper and Second Permeable Zones. The Upper and Second Permeable Zones were characterized hydrologically to determine the most applicable remedial alternative for addressing the dissolved DNAPL plume. Pilot tests consisting of soil vacuum extraction (SVE), combined air sparging with SVE (AS/SVE), and groundwater recovery were performed. Evaluation of these remedial technology alternatives resulted in the selection of the combined AS/SVE system alternative for the Upper Permeable Zone and the groundwater recovery alternative for the Second Permeable Zone. Recoveredmore » off-gas from the combined AS/SVE treatment system from the Upper Permeable Zone is treated through use of a granular activated carbon unit, while recovered groundwater form the Second Permeable Zone is treated by use of a low-profile air stripper.« less

Distribution of geological materials in Lower Hutt and Porirua, New Zealand

Geological materials in the Lower Hutt, Eastbourne, Wainuiomata, and Porirua urban areas are mapped and described as part of a multi-disciplinary assessment of seismic ground shaking hazards. Emphasis is mainly on the flat-lying parts of these areas which are underlain by variable Quaternary-age sediments that overlie Permian-Mesozoic age 'greywacke' bedrock. Within the Quaternary-age sediments, the two material types recognised on strength characteristics are:
 1) Soft sediments, typically composed of normally consolidated, fine-grained materials (sand, silt and clay), with typical standard penetration values (SPT) of <20 blows/300 mm; and 
 2) Loose to compact coarser-grained materials (sand, gravel), with SPT values of >20 blows/300 mm. 
 The total thickness and nature of Quaternary-age sediments in the study areas is described, with particular emphasis on the thickness and geotechnical properties of near-surface sediments. Such sediments are considered likely to have a significant influence on the an1plification and attenuation of ground shaking intensity during earthquakes.
 In the Lower Hutt valley, near-surface soft sediments greater than 10 m thick have an areal extent of -16 km2. Such soft sediments underlie much of Petone and the Lower Hutt urban and city centres, and have a maximum known thickness of 27 m near the western end of the Petone foreshore. In the Wainuiomata area, near-surface soft sediments greater than 10 m thick have an areal extent of - 3 km2, and attain a maximum thickness of 32 m. In Porirua, near-surface soft sediments have a maximum thickness of 14 m, cover an area of -2km2, and underlie much of the city centre. In the Lower Hutt valley the total known thickness of Quaternary-age sediments, including near-surface soft sediments is 300 m. Quaternary-age sediments are very much thinner in other areas, with thicknesses of 60 m recorded in Wainuiomata, 10 m in Eastbourne, and 90 m in the Porirua area.

Mini-Sosie High Resolution Seismic Reflection Profiles Along the Bootheel Lineament in the New Madrid Seismic Zone

Abstract Results of geological and geophysical research conducted in the New Madrid seismic zone since the early 1970’s indicate that much of the seismicity of the area is associated with late Precambrian age rift-related geological structures that have been reactivated by contemporary stresses. Deep seismic reflection surveys have been used to detect and delineate deeply buried geological structures thought to be associated with the seismicity. Satellite imagery and aerial photographs have recently been used to detect a linear feature named the Bootheel lineament inferred to be the surface expression of one of the faults responsible for the 1811–1812 earthquakes. To assess the seismogenic potential of these deep structures and linear features, high resolution seismic reflection and geomorphic studies are required. In July and August, 1990, Mini-Sosie high resolution reflection surveys were conducted in the New Madrid seismic zone. A total of 23 line-kilometers of high resolution reflection data were collected at nine locations. Specific targets for the new surveys include several locations on the Bootheel lineament in the New Madrid area, its northern projection near Sikeston, Missouri, and its southern projection near Blytheville, Arkansas at locations related to the Blytheville arch. A location several kilometers south of Charleston, Missouri, was also selected. Data presented in this paper consist of 7 line-kilometers recorded at locations on or close to the Bootheel lineament near New Madrid, Missouri, Hayti, Missouri, and Blytheville, Arkansas. Numerous small-offset faults, channels and other structures in Tertiary, Cretaceous and Paleozoic age rocks have been interpreted from the Mini-Sosie seismic sections. These structures, although generally not major features themselves, may be associated with deep seated rift-related reactivated structures. Many of the small-offset faults appear to deform or offset Quaternary age sediments. The spatial correlation of the observed faulting with sandblows and lineaments identified from aerial photographs, suggests the possibility that the observed faulting, sandblows, and linear features may be genetically related. If this is the case, then, because the origin of the sandblows has generally been attributed to the 1811–1812 seismic activity, the observed faulting may have been active at that time. It is not possible to directly link a single correlatable seismic signature with the Bootheel lineament, and thus we cannot state unequivocally that the lineament is continuous from Blytheville, Arkansas to New Madrid, Missouri. However, each seismic line has imaged similar small-offset faulting and gentle folding. If the faults and deformation observed are directly caused by reactivated deep structures associated with the Bootheel lineament, then, due to its great length, the total of which is yet undefined, this structure may be a source zone for major earthquakes, and therefore requires further investigations. The possibility exists, however, that the small scale faulting and deformation are ubiquitous throughout the New Madrid seismic zone. Additional high resolution seismic data are required to resolve this question.

Role of organic matter and particle fabric in mass-physical and geotechnical properties: Implications for undrained slumping in Aegean Sea and Ionian Sea modern sediments

Water content, bulk density, undrained shear strength, Atterberg limits (liquid limit ( W I) and plasticity index ( I P)), the clay fraction, and organic matter contents have been measured in sediments of Quaternary age from the Aegean Sea and Ionian Sea. The sediments include sequences of colour-graded clays ranging from yellow to black (sapropels), which express the evolution of the depositional environment from oxidising to reducing. Pyroclastic layers (tephras) are interbedded with the clays. The results show the following: (1) There are three main factors controlling change in mass-physical properties, particularly water content and plasticity. The first is sedimentation rates and smectite contents: the sediments of the Aegean Sea, of which sedimentation rates and smectite contents are higher, slightly differ from the sediments of the Ionian Sea: The Aegean sediments have a W I value of 50–80 and an I P value of 20–35, while the values for the Ionian sediments are 45–65 and 25–35, respectively. The second factor is the concentration and stage of decomposition of organic matter. Thus, for sapropels deposited between the past 125,000 to 7500 years, the water content varies from 100 to 400% and the W I and I P from 50 to 210 and 25 to 35, respectively. The third factor is the particle arrangement of the sediments. This is particularly significant in pyroclastic layers: tephras composed of rounded particles have an I P value lower than 16, and tephras composed of platey particles have a value higher than 30. (2) The second important result is that the organic-rich layers with high water content and low wet bulk density may lead to slope failure planes and earthquake-generated undrained slumping, particularly in the steep trench slopes.

Gelatinous pellicles in deep anoxic hypersaline basins from the Eastern Mediterranean

Gelatinous pellicles have been observed in three out of ten cores recovered from the Bannock Basin (or Bacino Bannock) and in two dredges from its flanks during a cruise of the R.V. Bannock in the Eastern Mediterranean. Similar pellicles have also been detected in two cores recovered from the Tyro Basin. The Bannock and Tyro basins are brine-filled depressions which are presently characterized by anoxic sedimentation; in the Bannock Basin also gypsum precipitation occurs. The gelatinous pellicles, some millimeters thick and dark grey to greenish in color, are always found in very dark colored sediments of Quaternary age. These pellicles have been investigated by optical microscopy, by scanning electron and transmission electron microscopy, and by flash pyrolysis-gas chromatography and flash pyrolysis-gas chromatography-mass spectrometry to decipher their nature. Abundant skeletal tests of siliceous and calcareous planktonic organisms (radiolaria, diatoms, silicoflagellates, formainifera and nannofossils) are observed, together with amorphous organic matter. The pellicles enclosing these remains consist of organic matter; they foliate into submillimetric undulating and anastomosing microlaminae. Cellular structures are never observed, neither in the pellicles nor in the microlaminae. Organic geochemical analyses point to a high contribution of terrestrial material. The organic matter of the pellicles investigated consists of a “coal-like” material. It is suggested that the pellicles are originally formed at the brine-seawater interface, but subsequently sink to the bottom due to increasing load of entrapped biogenic and non-biogenic detritus.

Sieving Techniques in Palynological Sample Processing with Special Reference to the MRA System

Sieving Techniques in Palynological Sample Processing with Special Reference to the MRA System

Role of submarine canyons in shaping the rise between Lydonia and Oceanographer canyons, Georges Bank

Three large submarine canyons, Oceanographer, Gilbert, and Lydonia, indent the U.S. Atlantic continental shelf and, with four additional canyons, dissect the continental slope in the vicinity of Georges Bank. On the upper rise, these canyons merge at a water depth of approximately 3100 m to form only two valleys. Differences in channel morphology of the canyons on the upper rise imply differences in relative activity, which is inconsistent with observations in the canyon heads. At present, Lydonia Canyon incises the upper rise more deeply than do the other canyons: however, seismic-reflection profiles show buried channels beneath the rise, which suggests that these other six canyons were periodically active during the Neogene. The rise morphology and the thickness of inferred Neogene- and Quaternary-age sediments on the rise are attributed to the presence and activity of the canyons. The erosional and depositional processes and the morphology of these canyons are remarkably similar to those of fluvial systems. Bear Seamount, which has approximately 2000 m of relief on the rise, has acted as a barrier to downslope sediment transport since the Late Cretaceous. Sediment has piled up on the upslope side, whereas much less sediment has accumulated in the “lee shadow” on the downslope side. Seismic-reflection profile data show that Lydonia Canyon has not eroded down to the volcanic rock of Bear Seamount.

Tertiary Stratigraphic Units of Western Mojave Desert, California

Scattered throughout the western Mojave Desert, mostly in the vicinities of Rosamond, Mojave, and Boron, are exposures of non-marine sedimentary and volcanic rocks of Tertiary age. These rocks rest on a deeply eroded surface of pre-Tertiary granitic and metamorphic rocks that form the crystalline basement complex of this region, and are overlain unconformably by alluvial sediments of Quaternary age. Where exposed the Tertiary rocks are moderately deformed and much eroded. With the exception of exposures in the foothills northwest of Mojave, the rocks of Tertiary age are mapped as a group, named the Tropico group, with a maximum exposed thickness of about 2,800 feet. This group is divided into several lithologic units of local extent. In most sections the lower unit is a pyroclastic formation, with associated rhyolitic intrusions and flow-breccias, and the upper unit is either fanglomerate or a sequence of carbonate rocks, clays, and sandstones of lacustrine and fluviatile origin. Several basalt flows occur locally in the group, mostly in the middle part. The group is non-fossiliferous except at one locality, where diatom remains in the upper unit suggest early Pliocene age. The lower unit is tentatively correlated with lithologically similar formations of known Miocene age in areas west and northwest. Formations in the Tropico group that are locally distinct are named the Gem Hill formation, Fiss fanglomerate, Bissell formation, Saddleback basalt, and Red Buttes quartz basalt. In the foothills northwest of Mojave the granitic basement is overlain by about 1,000 feet of terrestrial sandstones and clays named the Horned Toad formation. This formation yielded a mammalian fauna indicating middle or early Pliocene age, and is either younger than or correlative with the upper part of the Tropico group.