Eocene Clay Research Articles

Soil pore water evaporation and temperature influences on clay mineral paleothermometry

Clay mineral isotope paleothermometry is fundamental to understanding Earth’s climate system and landscape evolution. Status quo methods, however, assume constant factors, such as formation temperature and water isotopic compositions, and ignore seasonality, soil water evaporation and depth-dependent temperature changes. We propose first-order modifications to address these factors and test them in a modeling framework using published data from various settings. Our forward model reveals that neglecting evaporation and seasonal soil temperature variability may lead to significant underestimations of clay formation temperatures, especially in Mediterranean settings. Our inverse model indicates that high-latitude Eocene clay formation temperatures were ~8 °C warmer than modern, while Eocene river sediments in the Sierra Nevada show evaporation-influenced trends, suggesting that previous paleoelevation estimates were underestimated. Our framework demonstrates that explicit consideration of soil pore water evaporation and temperature variability is necessary when interpreting clay mineral isotope data in the context of temperature, hydroclimate and elevation reconstructions.

Assessment of the Effect of Bench Terracing in El Ogla and El Hadada Watersheds in Tunisia in the Context of Gully Erosion

The study of the erosive manifestation in El Ogla and El Hadada watersheds showed a strong and accelerated erosive dynamic. The aggression of the rains, the unstable nature of the Lower Eocene clays and the pressure of humans on the marginal lands seem to be at the origin of the instability of the slopes. Thus, the preservation of lands requires a colossal effort from the part of the State as well as the peasants. Unfortunately, the majority of developments have been implemented on an ad hoc basis and are far from being implemented comprehensively. In El Ogla and El Hadada watersheds, bench terracing is the most spectacular form of State intervention. It is considered by technicians as the unique solution for all forms of erosion. However, the appearance of forms of failure in various sectors cannot neglect the good functioning of some of them in the stability of the slopes and the reduction of the water slide. The objective of this applied research is to evaluate the behaviour of these benches as an interactive system with the other components of the natural environment based on photointerpretation, field monitoring and the results of the diagnosis of the balance sheet displacement of sediments obtained from the application of the isotopic method of Cesium 137. This assessment of bench terracing is largely based on the Bugeat formula, which seems to be the most appropriate method for determining the suitable dimensions of both height and terrace spacing.

Bentonite clays of the Central Kyzylkum and their material composition and engineering and geological properties, Uzbekistan

The authors consider the conditions of occurrence, composition, and properties of the Eocene clays of the Paleogene, common in the northern part of Tamdytau, which were the foundation of the structures. The present study of the authors is aimed at studying the problem of the long-term interaction of Eocene clays with water and identifying the features of changes in their material composition and properties; the variability of the composition, properties of clays, and the reasons for these changes are analyzed. The main factors determining the differences in the composition and properties of Paleogene clays are: genetic - different salinity of the sea basin or less saline at which the reservoirs were connected with the open sea; zonal-climatic - different humidity and other physical properties. So far, no unified methodology has been developed for predicting the composition and properties of clays at the base of structures when interacting with water. The results of granulometric analysis established that Paleogene clays are classified as highly dispersed soils containing more than 55% of clay particles. Analysis of the diffraction pattern showed that the clay fraction of the studied samples contain montmorillonite (M), hydromica (H), kaolinite (K), mixed-layer formations of the montmorillonite-hydromica series.

Tension tests on bored instrumented piles installed in marine Eocene clay

This paper presents parts of the results from two full-scale loading tests (tension) on bored cast-in-place piles installed in high plasticity marine Eocene clay at a test site in Hinge, central Jutland, Denmark. Testing was carried out to investigate the development and distribution of shaft resistance on the test piles. Each test pile was instrumented with distributed fiber-optic strain and temperature cables, in addition to traditional vibrating wire strain gauges and tell tales. Selected examples of retrieved data are presented. The measured shaft resistance is compared to an analytical method based on the Danish National Annex to Eurocode 7, part 1 which represents a conservative estimate for the shaft resistance of bored piles. The results from the two full-scale loading tests (tension) on bored cast-in-place piles in marine Eocene clay show that the Danish code-requirement, concerning shaft resistance, is too conservative.

Trophism, climate and paleoweathering conditions across the Eocene-Oligocene transition in the Massignano section (northern Apennines, Italy)

The Eocene-Oligocene transition represents the latest greenhouse-icehouse shift faced by Earth, a major global climate change associated with carbon cycle perturbation. In this paper, we investigate the Massignano stratigraphic section (northern Apennines, Italy), GSSP of the Eocene-Oligocene boundary, by X-ray diffraction analysis of clay minerals and carbon and oxygen stable isotopes to explore the link among climate, paleoweathering and runoff, and carbon cycle in the Neotethys across this major climatic transition. We examine the interplay between global climate forcing and orogen evolution controlling the Massignano hemipelagic sedimentation. The late Eocene clay mineral assemblages indicate that the Neotethys was sensitive to global eustatic changes as well as changes in composition and rates of weathered sediments accumulating into the basin. The carbon isotope record matches with the global signal, showing productivity pulses linked to cooling phases and sea-level drops before 34.8 Ma. Subsequently, a constant negative trend is recorded, which is consistent with the global carbon isotope curve, and attests for a decrease of primary productivity linked to decreasing atmospheric CO2. This negative trend ends at the Eocene-Oligocene boundary, when the onset of the global carbon isotope positive excursion is recorded also within the Massignano hemipelagic succession. On the contrary, the clay mineral assemblage is quite constant across the Eocene-Oligocene boundary reflecting the complex interplay among fluvial discharge, sea level changes and orogen dynamics which clouded the global climate shift. In this context, the enhanced fluvial discharge likely contributed to sustain high trophic conditions in the Adriatic waters and, in turn, the Oligocene positive carbon isotope shift. These results highlight how clay minerals proved to be a useful proxy to identify the interplay between global and regional controlling factors on hemipelagic sedimentation and, their integration with the carbon isotope record, provides insights into carbon cycle dynamics.

ENGINEERING AND GEOLOGICAL PROPERTIES OF EOCENE CLAYS OF THE NORTHERN TAMDYTAU AS THE BASIS FOR ENGINEERING STRUCTURES

ENGINEERING AND GEOLOGICAL PROPERTIES OF EOCENE CLAYS OF THE NORTHERN TAMDYTAU AS THE BASIS FOR ENGINEERING STRUCTURES

Application of magnetic and resistivity for groundwater investigations at North Al Ain Sokhona – Cairo Road, Al Ain Sokhna, Egypt

ABSTRACT The present study aims to delineate different types of the ground water accumulations in the northwest Gulf of Suez using geoelectrical and magnetic measurements. Twenty-one Vertical Electrical Soundings (VES) to determined groundwater potentialities. Based onthe quantitative geoelectrical analysis, the subsurface sequence consists of six geoelectrical layers; The first layer belonging to Quaternary period and built up of dry sand and gravels. The second layer belonging to the upper Miocene and built up of sandstone and limestone. The thirdlayer belonging to middle Miocene and formed of limestone and sandy clay. The fourth layer belonging to lower Miocene and composed of limestone and clayey limestone. The fifth layer belonging to the Oligocene and Upper Eocene clay and consists of clayey and sandstone. The sixth layer belonging to the Middle Eocene composed of limestone. Quantitative geoelectrical analysis of the study area also concluded that there are two water-bearing geoelectrical layers (aquifers), the second geoelectric unit represents the fresh water aquiferwhile the third geoelectric unit layer represents the brackish aquifer. The results of magnetic interpretation indicate that the area under study dissected by fault elements of N-S and NE-SW. The depth to the basement ranges from (1925–1998 m).

Temperature-dependent frictional properties of heterogeneous Hikurangi Subduction Zone input sediments, ODP Site 1124

The Hikurangi Subduction Zone (HSZ), New Zealand, accommodates westward subduction of the Pacific Plate. Where imaged seismically, the shallow HSZ décollement (<10–15km depth) occurs within or along the upper contact of Late Cretaceous-Paleogene (70–32 million-year-old) sediments. The frictional properties of Paleogene sediments recovered from Ocean Drilling Program Leg 181, Site 1124 were measured at 60MPa effective normal stress and varying sliding velocities (V=0.3–30μm/s) and temperatures (T=25–225°C). Velocity-stepping experiments were conducted at temperatures of 25°C, 75°C, 150°C, and 225°C to determine the friction rate parameter (a–b). Paleocene and Oligocene clay-bearing nannofossil chalks (μ=0.45–0.61) and a middle Eocene clayey nannofossil chalk (μ=0.35–0.51) are frictionally stronger than smectite-bearing Eocene clays (μ=0.16–0.31). With increasing temperature, chalks show rate-strengthening to rate-weakening frictional stability trends; clays show rate-weakening and rate-neutral to rate-strengthening frictional stability trends. The results obtained from Site 1124 sediments indicate that: (1) fault-zone weakness may not require pore-fluid overpressures; (2) clays and chalks can host frictional instabilities; and (3) heterogeneous frictional properties can promote variable slip behaviour.

Influence of structure on the compression behaviour of two very stiff fissured high plasticity Eocene clays

A series of one-dimensional compression tests have been performed on reconstituted specimens of Søvind Marl. A clear correlation is obtained between the location and the gradient of the intrinsic compression lines and the void ratio at the liquid limit. The found correlation has subsequently been used to normalise the compression curves of 12 one-dimensional compression tests on intact specimens of Søvind Marl and Little Belt Clay obtained from various depths at two sites at Aarhus Harbour. Søvind Marl and Little Belt Clay are both marine sedimentary clays of Eocene age, which can be characterised as very stiff fissured clays with a very high plasticity. From a comparison of the reconstituted and intact compression paths the influence of structure is analysed and discussed in the paper. The majority of intact specimens of Søvind Marl and Little Belt Clay from Aarhus Harbour show similar behaviour; a very stiff recompression path and yielding at high stress level after crossing the intrinsic compression line. The displayed behaviour indicates an insignificant influence of fissuring on the pre-yield behaviour. Post-yield the compression paths indicate a stable structure dominated by fabric rather than metastable interparticle bonds. The paper furthermore highlights the importance of considering the effect of pore water salinity when assessing the influence of structure on the compression behaviour of smectite rich natural marine clays.

Characterization of Ain M’Dheker clay deposits for sunflower oil and Acid Black 194 dye clarification

Three mixtures (M1, M2, and M3) of the Eocene clay deposits were collected from Ain M’Dheker (Enfidha, Tunisia). These mixtures have been treated by hydrochloric acid in order to improve their physico-chemical characteristics. Optimum conditions for activation were conducted by varying several parameters such as the acid concentration, time, and temperature activation. The activation condition effect on surface area is studied. A representative raw (M3) and activated (AM3) mixtures were used in industrial application: Sunflower oil and Black 194 dyes (textile waste). M3 and AM3 were used to leach sunflower oil by varying the clay amount introduced. Results of the bleaching power of used samples were compared to that found by commercial bentonite imported from Germany (Tonsil), having a surface area of 725 m2/g. Indeed, an amount of 1% of AM3 gives a 60% decolorization similar to that found by commercial clay. Also, the ability of raw and activated clay to remove the dye (Acid Black 194) from effluent has been studied firstly at different pH and in second time by varying the adsorbent amount. Then, an amount of 0.025 g is sufficient to give a higher adsorption capacity for M3 than AM3. Consequently, Ain M’Dheker clay deposits can be use in other environmental application even without any treatment.

Middle Eocene clay from Goset Abu Khashier: Geological assessment and utilization with drinking water treatment sludge in brick manufacture

This investigation aims to study the physico-ceramic properties of bricks that were made from the Goset Abu Khashier clay (Qarara Formation, Middle Eocene deposits, El-Minia, Egypt) replaced with 15–60wt% drinking water treatment sludge (DWTS). The Qarara Formation deposits located in the east bank of the Nile River between Beni Suef and El-Minia Governorates, belong to the Middle Eocene deposits. The Qarara Formation deposits in the Goset Abu Khashier area contain several million tons of clay deposits. The Qarara Formation is composed of a grey to green shale (silty clay) grading upward to marl and limestone. The clay contains kaolinite (29wt%), montmorillonite (20wt%), albite (27wt%) and quartz (23wt%). The clay contains a high content of silica (49.41wt%) and a low content of alumina (19.77wt%) with considerable amounts of Fe2O3 (11.37wt%) and fluxing oxides (3.7wt%). Clay bricks containing 15–60wt% DWTS were fired at a temperature of 700–1000°C. The ceramic properties of bricks were determined according to the ASTM specifications. The phase composition of bricks was determined by XRD, FTIR and SEM techniques. It was investigated that the incorporation of DWTS in the body of clay bricks moderates the ceramic properties of fired bricks to be in agreement with the limiting values that were recommended for traditional bricks. XRD results illustrated that dehydration of kaolinite and the formation of metakaolinite facilitates vitrification and contributes to brick densification. FTIR results showed the formation of a wollastonite phase and indicated that increasing DWTS content facilitates the persistence of a vitrified phase. SEM micrographs illustrated that the porosity and densification of brick matrix was affected by the formation of amorphous vitreous phases and decreased with DWTS contents. It is recommended that the replacement of examined clay by 15–30wt% of DWTS is considered as the appropriate percentage for building bricks production and minimizes environmental impacts due to DWTS disposal into water bodies.

Basic activation of lower Eocene clay from Meknassy-Mezzouna basin (centerwestern Tunisia), synthesis of zeolite and clarification of soybean oils

The present work is interested particularly in a basic activation of smectitic clay by solid Na2CO3. The clay samples, belonging to Ypresian Chouabine formation, are taken from the lithological section made in the Oued Errizgui (Jebel Meheri El Jebbes) in the Meknassy-Mezzouna basin. Chemical characterization and mineralogical study shows that studied clays are mostly smectitic and associated with a small amount of sepiolite and palygorskite. The accessory minerals correspond to quartz and dolomite. Moreover, relatively high specific surface (50.47m2/g) encourages the activation of these clays by Na2CO3. Thus, the optimal activation conditions were obtained for 5% Na2CO3 at 75°C during 1h. Under these conditions, the specific surface of smectitic clays increases to 58.63m2/g. The basic activation can cause dissolution of dolomites, crystal grow of zeolites, recrystallization of smectite and Na=Ca ionic exchange between Ca-smectite and basic solution. The activated smectitic clays provide better results compared to those given by the Tonsil product used for the clarification of neutral soybean oils by the refinery of SATHOP and SOZITEX companies. In fact, the bleaching power of the activated clay is much better (71.48%) than that of the Tonsil (56.12%). This is corroborated by the visual examination of the clarified oils.

Studying the thermal conductivity of a deep Eocene clay formation: Direct measurements vs back-analysis results

An experimental study on Ypresian clays–one of the potential deep and sedimentary clay formations in Belgium for the geological disposal of heat-emitting radioactive waste–has been undertaken to systematically study its thermal conductivity using different experimental techniques. As a first step, a new experimental setup with heat flux measurement has been used and careful pre-conditioning protocols have been followed to directly measure this thermal property. The aim of these pre-conditioning tests has been ensuring a very high degree of saturation and the closure of fissures / gaps along bedding planes before the thermal tests are run under low stress conditions. Thermal tests have shown to be particularly sensitive when the thermal conductivity is determined along a direction orthogonal to these bedding planes. The study is then complemented by using a constant volume heating cell, in which heating pulse tests have been carried out under fully saturated conditions that have been ensured with a high water back-pressure. Numerical models have been used to interpret this pulse test, to exploit all the information provided by temperature measurements and to back-analyse the thermal conductivity. Direct thermal conductivity data with the improved pre-conditioning protocol allowed obtaining results consistent with the values reported when using back-analysis in the constant volume cell. The article discusses the importance of restoring full saturation conditions, particularly on retrieval of deep sedimentary clays, which may undergo opening of fissures along bedding planes that may affect the correct determination of the thermal conductivity.

HE INFLUENCE OF GEOLOGY ON THE COURSE AND OUTCOME OF THE THIRD BATTLE OF YPRES (FLANDERS, WW1)

Geological structure of the terrain as a ground for a battlefield could be a significant factor for the success or failure of a military operation. The geology of the Belgian town of Ypres was an important, maybe even crucial factor, of the failure of the WWI Allied Powers offensive military operations against German Axis forces in 1917. The Early Eocene clays found at the ground surface at Ypres, coupled with excess precipitation, turned out to be utterly inappropriate for the fortification, movement, fighting and manoeuvring of all military units, especially the armoured units that were directed towards hardly passable routes. With selecting the unsuitable and hardly passable terrain, that is the direction of the attack, the British army had losses of the available combat potential and armoured forces were ineffective during the battle. The total number of Allied casualties was 448,000 dead, wounded, imprisoned and missing. This paper offers other possible solutions that would, from a military geographic and military geological viewpoint, have made a better solution for achieving the strategic goal required by the Allies on the eve of the Third Battle of Ypres in 1917.

Earth pressure at rest of Søvind Marl — a highly overconsolidated Eocene clay

The present study evaluated the earth pressure at rest, K0, of Søvind Marl, a highly overconsolidated Eocene clay. This clay exhibits extremely high plasticity indices of up to 300%, a highly fissured structure, and preconsolidation stresses up to 6800kPa. Continuous Loading Oedometer (CLO) tests at a constant rate of strain were performed in the Danish CLO apparatus. This apparatus applies test water at 200kPa and measures total horizontal stresses via pressure gauges placed in a stiff oedometer ring. Horizontal and vertical stresses were measured from in situ stresses to various stress levels to estimate continuous K0 development in the clay. Normally consolidated earth pressures at rest were 0.42 and 0.68 for Søvind Marl at two different ages. Overconsolidated K0, K0(oc), reached values as high as 6 to 8 in the in situ stress range. The correlation between K0(oc) and the overconsolidation ratio, OCR, reported by Meyerhof in 1976 was inconsistent with the K0(oc) development of Søvind Marl. However, the development of OCR in the laboratory under the previously applied test stresses, OCRlab, as an alternative to preconsolidation stresses, showed congruent results regardless of sample age when an α-value of 1.05 was used.

Preconsolidation of Søvind Marl—A Highly Fissured Eocene Clay

Abstract Determination of the preconsolidation stresses is a key tool in geotechnical engineering used to evaluate and estimate the behavior of soils. However, it has proven difficult to accurately estimate these stresses in highly fissured, overconsolidated clays, due to the influence of the fissured structure. In the current study, oedometer tests were performed on Søvind Marl, a plastic Eocene clay containing a large number of fissures and slickensides. Four incremental loading oedometer tests and four continuous loading oedometer tests were performed in order to determine the preconsolidation stresses. Multiple assessment methods were used to assess preconsolidation stresses based on the oedometer test data, results of which are presented and discussed on this paper. All of the test and interpretation methods yielded very similar results, with two possible values calculated as the preconsolidation stresses. However, only the upper stress bound is actually identified as being associated with preconsolidation; the lower bound is generated as a result of the collapse of the fissured structure in response to increasing stresses that were applied during testing. The upper bounds of the preconsolidation stresses of Søvind Marl were between 6300 and 8900 kPa, whereas the lower were between of 600 and 800 kPa.

Alunite characterization in the upper Eocene clay deposits of Central Tunisia: an implication to its genesis

Alunite mineral was recently identified at the upper Eocene clay deposits associated with laminated primary gypsum and iron oxide in Central Tunisia, particularly at El Gnater site. The alunite characterization has been performed by several analytical techniques [atomic absorption spectroscopy (AAS), X- ray diffraction (XRD), scanning electron microscope (SEM), thermogravimetric analysis (TGA) and differential thermal analysis (DTA)]. The mean features of their chemical composition are its deficiency of Al, water excess content, small replacement of K by Na and absence of impurities such as Fe. The X-ray diffraction pattern reveals the purity of the alunite samples. The SEM micromorphological study shows a compact facies which is made up by homogeneous pseudocubic microcrystals having approximately the same diameters of 1 μm. Thermal behaviour of El Gnater alunite closely matches published literature which shows two major endothermic peaks at 528 and 744 °C with total weight loss 17.27 and 29.09 %, respectively. The former corresponds to the dehydroxylation processes and the latter corresponds to sulphate decomposition reaction. The association of studied alunite with laminated primary gypsum, hematite and clay minerals implies its late diagenetic origin in reduced conditions and in evaporitic environment. However, jarosite was produced by oxidation of pyrite which was very abundant in the claystone host.

Calcareous nannofossil and foraminifer biostratigraphy of the Campanian–Maastrichtian chalk of the Femern Bælt (Denmark–Germany)

A new study based on calcareous nannofossil and benthic and planktonic foraminifer biostratigraphy is presented for the upper Campanian – Maastrichtian chalk of the Femern Bælt (Denmark and Germany; Fig.1). The results are consistent with recent studies of the Danish chalk for this interval, allowing correlation across the Danish Basin and forming the basis for correlation further afield within the Boreal Realm. Numerous studies have been carried out recently on the upper Campanian – Maastrichtian chalk of the Danish Basin, covering aspects such as sedimentology, depositional environment, macrofossil biostratigraphy, carbon isotope stratigraphy as well as nannofossil and dinoflagellate biostratigraphy. However, very few published studies on foraminifers exist across this interval in this area. The 09.A.006, 09.A.007 and 09.A.008 boreholes (Fig. 2) were drilled in 2009 in preparation for construction of a fixed link across the Femern Bælt, which will connect Denmark to Germany (Rambøll Arup JV 2011). The boreholes penetrated glacial till, Paleocene– Eocene clay and chalk (Sheldon et al. 2012). Here, for the first time, the Boreal foraminifer biostratigraphy of the late Campanian – Maastrichtian interval is investigated and presented alongside nannofossil biostratigraphy.

Palynological and microfossil biostratigraphy and palaeoecology over the Paleocene–Eocene transition, Femern Bælt, northern Germany

A palynological and micropalaeontological biostratigraphic and palaeoecological investigation has been carried out on the Paleocene–Eocene transition of core 10.A.057 from the Femern Bælt (Fig. 1). Initial investigations of boreholes from the Femern Bælt indicated that core 10.A.057 included a thick succession of Upper Paleocene – Lower Eocene clay (Sheldon &amp; Nøhr Hansen 2010; Rambøll Arup JV 2011; Fig 2). Complete Paleocene–Eocene sections have been described from Jylland and the Storebælt (Heilmann-Clausen 1985, Laursen &amp; Andersen 1997; Laursen &amp; King 2000, Nielsen et al. 1986), but no detailed studies have been published on these successions from the Femern Bælt. Boreholes were drilled on Lolland in Denmark, under the Femern Bælt and on Fehmarn island, Germany from 2009 to 2011 as part of geological and geophysical investigations performed in preparation for the construction of a fixed road and rail link connecting Denmark and Germany. The boreholes penetrated Campanian – Upper Eocene strata, overlain by Quaternary deposits. Borehole 10.A.057 is located in the southern part of the Femern Bælt (Figs 1, 2).

Endocarps of Prunus (Rosaceae: Prunoideae) from the early Eocene of Wutu, Shandong Province, China

AbstractEndocarps of the genus Prunus (family Rosaceae) have been described from early Eocene clay deposits in the Wutu Coal Mine, Shandong Province, China. Endocarps are elliptical or ovoid in lateral view, with a long canal that approaches the apex of the endocarp and contains the ventral vascular bundle. Comparisons with related living and fossil species of Prunus indicate that these endocarps should be assigned to Prunus wutuensis sp. nov. The endocarps from Wutu represent the earliest record of Prunus in Asia. Based on the distribution of fossil Prunus endocarps, the palaeobiogeographic history of the genus is shown on palaeogeographic maps of the Northern Hemisphere. The fossil data suggest that the genus first appeared in the early Eocene of North America and Asia, and then extended to Europe in the middle Eocene.