Re-evaluation of the phylogeny of Early Cretaceous planktonic foraminifera (Praehedbergellidae)

Tunisia, Ukraine, Russia, the North Sea area and elsewhere have yielded knowledge that the Early Cretaceous planktonic foraminifera are predominantly members of the Praehedbergellidae. The taxonomy and phylogeny of this family have been revised and refined. New generic and specific taxa have been proposed, new phylogenetic lineages have been described, and many type specimens have been imaged by scanning electron microscopy for the first time.Gorbachikella(Hauterivian–Early Aptian) gave rise toPraehedbergella(Late Hauterivian–Late Aptian), evolvingBlefuscuiana,Lilliputianella, and the planospiralBlowiellain the Barremian. The last gave rise toGlobigerinelloidesin the Aptian, from which the macroperforateAlanlordella(and its descendantPlanomalina) evolved in the Albian.Blowiellawas ancestral to taxa with radially elongated chambers (Claviblowiella, Leupoldina, Schackoina).     

Theoretical modelling of cis -vacant and trans -vacant configurations in the octahedral sheet of illites and smectites

 The cis-vacant configurations of smectites and illites have been studied theoretically by using transferable empirical interatomic potentials. A wide range of compositions of octahedral and tetrahedral cation and interlayer charge has been considered. All results have been compared with the trans-vacant configurations in each sample. The calculated values reproduce the differences in the lattice parameters between the cis- and trans-vacant configurations of experimental studies. Taking into account the cis-/trans-vacant proportion, the calculated structures agree with experiment for the main structural features of the crystal lattice. The effect of the cation substitution in the octahedral and tetrahedral sheets on the cell parameters has been also studied, finding good linear relationships. The calculated cation substitution effects are consistent with experimental results. Although the energy difference between the cis- and trans-vacant configurations is small, the cis-vacant is more stable when the composition of clays is more smectitic, like the experimental behaviour. Similar trends of the cation substitution effect on the cis-/trans-vacant proportion to the experimental results are found. The structure of the hydroxy groups has also been analysed. The OH bond length, the orientation of the O–H bond with respect to the (001) plane and the non-bonding H...O distances have been studied. Received: 4 September 2000 / Accepted: 29 January 2001     

Bearing capacity of foundations on rock mass using the method of characteristics

The method of stress characteristics has been used for computing the ultimate bearing capacity of strip and circular footings placed on rock mass. The modified Hoek‐and‐Brown failure criterion has been used. Both smooth and rough footing‐rock interfaces have been modeled. The bearing capacity has been expressed in terms of nondimensional factors N_σ0 and N_σ, corresponding to rock mass with (1) γ = 0 and (2) γ ≠ 0, respectively. The numerical results have been presented as a function of different input parameters needed to define the Hoek‐and‐Brown criterion. Slip line patterns and the pressure distribution along the footing base have also been examined. The results are found to compare generally well with the reported solutions.     

Lower bound limit analysis of unsupported vertical circular excavations in rocks using Hoek-Brown failure criterion

The stability of vertical unsupported circular excavations in rock media, obeying generalized Hoek-Brown yield criterion, has been investigated by using the lower bound finite elements limit analysis. An axisymmetric analysis, composed of a planar domain with a mesh of three-noded triangular elements, has been carried out. The optimization problem is dealt with by using the semidefinite programming technique avoiding the need of either smoothing the yield surface or making any assumption associated with the circumferential stress (σ_θ). A detailed parametric study has been executed, and the effects of different input material parameters, namely, geological strength index (GSI), yield parameter (m_i), and the disturbance factor (D) on the results have been studied. For different height to radius ratios of the excavation, the computed results are presented in the form of nondimensional stability numbers. Failure mechanisms have also been investigated for a few typical cases. The results from the analysis have been compared with that evaluated separately with the application of the software OptumG2.     

Synchrotron-excited luminescence of natural zircon

The luminescence properties of two single zircon crystals from kimberlite of Yakutia have been studied, excited by the DORIS HASYLAB synchrotron, Germany, within energy range from the visible to the soft X-ray region (5–25, 50–200, and 500–620 eV) at temperatures of 300 and 10 K. The luminescence spectra in the range of 2.5 to 6.0 eV and excitation spectra of the main bands have been examined, the physical nature of the luminescence centers has been discussed, and the luminescence properties of a crystal containing growth (radiation) structural defects and a crystal with the same impurities but annealed in air at 1200°C are compared. The zoned structure of the mineral has been considered and the value of the energy gap (E _g) in the mineral has been estimated at 7.1 eV. Two groups of luminescence bands caused by impurities of intrinsic (growth, radiation) nature (E _max = 2.1, 2.7–2.8, and 3.2–3.3 eV) and matrix luminescence (E _max = 4.4−4.7 and 5.4 eV) probably with the participation of excitons were distinguished on the basis of selective excitation of zircon with different synchrotron energies relative to the gap value (E _excit < E _g, E _excit ∼ E _g, and E _excit ≫ E _g). The short-lived component with a response time of 4 ns has been revealed in the afterglow of zircon in the region of 5.4 eV.     

Effect of Arching on Uplift Capacity of Single Piles

An analytical method has been proposed to predict the ultimate uplift capacity of single vertical piles embedded in sand considering arching effect. The present analysis takes into consideration of various pile and soil parameters such as length (L), diameter (d) of the pile, angle of internal friction of soil (ϕ), soil pile friction angle (δ) and unit weight of soil (γ). A modified value of coefficient of lateral earth pressure in uplift has been developed considering the arching effect of soil. A comparative assessment of the uplift capacity of piles predicted by using proposed theory and the existing available theories is made with the existing field and model test results. It has been observed that the present model considering the arching effect predicts the results closer.     

Quasi-harmonic computer simulations of the structural behaviour and EOS of pyrope at high pressure and high temperature

Numerical simulations, using empirical interatomic potentials within the framework of lattice dynamics and quasi-harmonic approximation, have been carried out to model the behaviour of the structure and of some thermoelastic properties of pyrope at high pressure and high temperature conditions (0–50 GPa, 300–1500 K). Comparison with observed data, available as a function either of P or of T, suggests that the pressure effects are satisfactorily modelled, whilst the effect of T on the simulations is underestimated. The cell edge, bond lengths and polyhedral volumes have been studied as a function of P along five isotherms, spaced by 300 K steps. These isotherms tend to converge at high pressure, which demonstrates that the pressure effects become dominant compared to those of thermal origin in affecting the structural properties far from ambient conditions. The cell parameter, bond distances, and other structural and thermoelastic quantities determined through simulations have been parametrised as a function of P and T by polynomial expansions. Bulk modulus and thermal expansion have been discussed in the light of the high-temperature-Birch-Murnaghan and of the Vinet P – V – T equations of state. The predictions of the bulk modulus versus P and T from the present calculations and from the Vinet-EOS agree up to 10 GPa, but they differ at higher pressure. Received: 23 October, 1998 / Revised, accepted: 23 April, 1999     

New Bathonian (Middle Jurassic) ammonite assemblages from Kutch, India

The Bathonian ammonite assemblages have been previously poorly recorded in Kutch. The present study has unearthed a rich array of ammonite taxa ranging from the Middle to Upper Bathonian. While Oxycerites Rollier (1909) is a new record from Kutch, the oldest occurrence of Choffatia Siemiradzki (1898) has been found from the Middle Bathonian horizon. Oxycerites cf. orbis (Giebel) is a zonal index of the Late Bathonian in other areas and thus facilitates interprovincial correlation. Besides, palaeobiogeographic and stratigraphic distribution of many species have been modified based on new information. For example, macrocephalitin species, i.e., Kamptokephalites cf. etheridgei Spath (1928), Macrocephalites bifurcatus transient intermedius Spath (1928), M. cf. mantataranus Boehm (1912) were previously known from West Pacific, Indonesia have been now found in Kutch. Gracilisphinctes Buckman (1920) has been previously known to occur during the Middle Bathonian time, the present work extends its stratigraphic distribution up to the definite Upper Bathonian horizon. Procerites hians (Waagen) an endemic species in Kutch previously known from the Upper Bathonian beds, its stratigraphic range has been extended down to the Middle Bathonian.Detail taxonomy of the newly obtained taxa has been done and in many cases sexual dimorphism has been recognized.     

Heterogeneities of the field of short-period shear wave attenuation in the lithosphere of Central Asia and their relationship with seismicity

The characteristics of the short-period shear wave attenuation field in the lithosphere of the Turanian Plate, West Tien Shan, Pamir, and Hindu Kush have been studied. The method based on analysis of the logarithm of the ratio between maximal amplitudes of Sn and Pn waves (Sn/Pn parameter) has been applied. More than 400 records of earthquakes, obtained at distances of ∼400–1000 km from the AAK digital station, have been processed. It has been found that relatively weak attenuation is observed in the regions of the West Tien Shan and Pamir. The largest area of strong attenuation is located in the region of the Afghan-Tadjik Depression adjacent to Hindu Kush. A wide band of low Sn/Pn parameter values, stretched northeastwards, has been distinguished. Along with the analogous band of strong attenuation, distinguished before in the regions of Central Tien Shan and Dzungaria, it is the continuation of the largest Chaman Fault, which stretches 850 km along the boundary of the Indian Plate. Source zones of strong earthquakes with M ≥ 7.0 that occurred in the first half of 20th century correspond to relatively weak attenuation. Areas of high attenuation, where strong seismic events have not occurred for the last 110 years, are outlined. Analogously to other seismoactive regions, it is supposed that these areas are related to preparation of strong earthquakes.     

Confirmation of an Early Cretaceous age for the Qihulin Formation in eastern Heilongjiang Province, China: constraints from a new discovery of radiolarians

The coal-bearing, alternating marine and non-marine Longzhaogou Group in eastern Heilongjiang, northeastern China, has long been considered as Jurassic, or mainly Jurassic, in age. However, recent studies have demonstrated that the ammonites and dinoflagellate cysts are of Early Cretaceous age. This has now been confirmed by new radiolarian evidence. The radiolarian fauna recovered from the upper Qihulin Formation of the Longzhaogou Group consists of nine poorly preserved species referable to nine genera. Novixitus is a Cretaceous genus, and the specimens of Archaeodictyomitra sp. and Xitus sp. recovered resemble A. vulgaris Pessagno and X. spicularius (Aliev), respectively.     

Palynological dating and correlation of surface and subsurface sediments from Wardha valley coalfield,Maharashtra

42 genera of palynomorphs have been reported from the qualitative and quantitative analysis of the palynoflora from both open cast mine and bore holes viz., Ballarpur open cast mine, Durgapur open cast mine and Bore hole CMWNM-57 on barrier between Kawadi/Majri open cast and Hindustan Lalpeth Colliery from the Wardha valley coalfield of Wardha basin. Two palynoassemblages have been recorded i.e., an Upper Karharbari palynoassemblage comprising dominance of radial monosaccate genus Parasaccites and subdominance of nonstriate disaccate genus Scheuringipollenites and a Lower Barakar palynoassemblage consisting of dominance of Scheuringipollenites and subdominance of striate disaccates chiefly Faunipollenites, suggesting an Early Permian age (Late Sakmarian to Early Artinskian) to the sediments. It is further authenticated by the occurrence of palynotaxa viz., Crucisaccites, Caheniasaccites, Indotriradites and Tiwariasporis. Upper Karharbari Formation has been demarcated for the first time in lithologically designated Barakar Formations in Ballarpur, Durgapur, Majri and Hindustan Lalpeth Colliery while the sample 57/2 of bore hole CMWNM from Kawadi area may belong to the Kamthi Formation on the basis of pinkish yellowish coarse grained to medium grained sandstone. An attempt has been made to correlate these palynoassemblages with other Lower Gondwana basins of Early Permian affinity.     

Stability of long circular tunnels in sloping ground

Assessment of tunnel stability has become increasingly crucial as more and more tunnels are built in difficult terrains such as sloping ground. The required support pressure on the tunnel walls associates both tunnel stability and liner design considerations. The present analysis attempts to find a uniform internal pressure which can support a circular tunnel built in a sloping ground with a particular level of stability in cohesive-frictional soils. The lower bound finite element limit analysis has been applied to find the required minimum uniform internal support pressure presented as a non-dimensional term p/c; where p is the minimum normal internal pressure on the tunnel boundary to avoid collapse and c is the cohesion of soil. The variation of p/c is presented for a range of normalised embedment depth of tunnel (H/D), stability number (γD/c), internal friction angle of soil (?) and slope angle (β); where H is the crown depth of the tunnel, D is the tunnel diameter and γ is the unit weight of soil. Appropriate comparisons have been carried out with available literature. Failure patterns of the tunnel have also been studied to understand the extent and the type of failure zone which may generate during the collapse.     

2p X-ray absorption of titanium in minerals

Ti 2p X-ray absorption spectra for a series of minerals have been measured. Crystal field multiplet calculations can explain the spectral shape. The asymmetry of the e _g , peak is shown to be related to distortions of the Ti ^IV octahedron. It is found, theoretically as well as experimentally, that the absorption spectra are more sensitive to tetragonal distortions than to trigonal distortions. A number of silicate minerals and metamict minerals containing titanium are measured and Ti ^III has not been observed in any of these minerals. A comparison is made to the 1s X-ray absorption, and the potential of both for the study of minerals is discussed.     

α- and β-diversity Change of Late Ordovician Hirnantia Fauna of Changning, Sichuan, Southwest China

A continuous Ordovician-Silurian boundary section from the upper Wufeng Formation through the Kuanyinchiao Formation to the lower Lungmachi Formation has been carefully measured and collected at Shuanghe of Changning, southern Sichuan Province. For the first time, the temporal changes of α- and β-diversities of the Hirnantia fauna have been discussed in great detail. The general trend of brachiopod diversity change, increasing upward, is consistent with the regional trend of the Yangtze Platform, which had been controlled by both intrinsic and extrinsic factors. However, the sudden drop of diversity for a short period in the upper Kuanyinchiao Formation might have been controlled by environmental factors rather than normal faunal turnover. Synecological analysis using numerical methods recognizes two brachiopod-dominated associations of the Hirnantia fauna, the Dalmanella-Kinnella Association and the Mirorthis Association, both living in an offshore, deeper water environment corresponding to BA3-upper BA4, particularly lower BA3.     

Fluid transfer of gold,palladium, and rare earth elements and genesis of ore occurrences in the Subpolar Urals

To estimate the behavior of Au, Pd, REE, and Y in magmatic and postmagmatic processes, a series of experimental studies on the solubility of noble metals and REE in magma, magmatic fluid, and hydrothermal solutions has been performed in wide temperature and pressure ranges (300–400°C, 860–1350°C; 1–14 kbar). The coefficients of Au and Pd partitioning (D ^F/L) between fluid and tholeiitic melt have been determined. Depending on P, T, and the composition of the system, they vary from 1 to 11 for Au and 0.02 to 1 for Pd. The phase solubility technique was used to determine Au and Pd solubility in hydrothermal fluid. The effects of temperature, composition, and fluid acidity on Au and Pd solubility have been estimated. The high solubility of these metals in aqueous chloride solutions has been established for both Au (28–803 mg/kg at T = 300°C, 305–1123 mg/kg at T = 350°C, and 330–1400 mg/kg at T = 400°C) and Pd (40–126 mg/kg at T = 300°C, 62–152 mg/kg at T = 350°C, and 20–210 mg/kg at T = 400°C). The coefficients of REE and Y partitioning (D ^F/L) between fluid and tholeiitic or alkaline melts have been determined. They vary from 0.00n to 2 depending on P, T, and fluid composition. The experimental data on Au and Pd solubility in solutions and magmatic fluids and the wide variation of REE D ^F/L between fluid and melt show that magmatic and hydrothermal fluids are efficient agents of Au, Pd, and REE transfer and fractionation. The obtained experimental data were used for elucidating sources of fluids and their role in the genesis of Au-Pd-REE occurrences in the Subpolar Urals.     

Paleo-Indian procurement of Camelops on the northwestern plains

Camelops have been recorded in a number of Paleo-Indian sites that lack evidence of past procurement methods. Recently, two occurrences of Camelops remains have been recorded in Paleo-Indian animal kills in Wyoming. One kill situation was in a Hell Gap cultural context that produced remains of a single Camelops taken along with about 100 bison in a parabolic sand dune trap. The other Camelops was in a Clovis cultural context and deals with a single animal believed to have been taken in an arroyo trap that was used to take bison at several Paleo-Indian time periods. Identification of geomorphic features involved in these kill sites offers a basis for beginning to interpret Paleo-Indian camel procurement methods.     

Bearing capacity of strip foundations reinforced with geogrid sheets by using upper bound finite‐element limit analysis

By using the upper bound finite‐elements limit analysis, with an inclusion of single and two horizontal layers of reinforcements, the ultimate bearing capacity has been computed for a rigid strip footing placed over (i) fully granular, (ii) cohesive‐frictional, and (iii) fully cohesive soils. It is assumed that (i) the reinforcements are structurally strong so that no axial tension failure can occur, (ii) the reinforcement sheets have negligible resistance to bending, and (iii) the shear failure can take place between the reinforcement and soil mass. It is expected that the different approximations on which the analysis has been based would generally remain applicable for reinforcements in the form of geogrid sheets. A method has been proposed to incorporate the effect of the reinforcement in the analysis. The efficiency factors, η_c and η_γ, to be multiplied with N_c and N_γ , for finding the bearing capacity of reinforced foundations, have been established. The results have been obtained (i) for different values of ? in case of fully granular and cohesive‐frictional soils, and (ii) for different rates at which the cohesion increases with depth for a fully cohesive soil. The optimum positions of the reinforcements' layers have also been determined. The effect of the reinforcements' length on the results has also been analyzed. As compared to cohesive soils, the granular soils, especially with higher values of ?, cause a much greater increase in the bearing capacity. The results compare reasonably well with the available theoretical and experimental data from literature. Copyright © 2013 John Wiley & Sons, Ltd.     

Comparisons between acoustic measurements and predictions of the bedload transport of marine gravels

Continuous, detailed records of marine gravel transport have been obtained acoustically and compared with bedload transport rates (q_b) predicted by five bedload transport equations using measurements of the near-bed turbulent current flow. When mean flow data are used in these equations, total q_b estimates are similar to those measured. However, when instantaneous flow data are used, total q_b is over-estimated by approximately one order-of-magnitude. Based on the acoustic measurements, an empirical equation has been obtained that gives accurate estimates of total q_b over a tidal cycle and simulates well the intermittent characteristics of marine bedload transport.     

Metamorphic history of the Jutogh Series in the Simla klippe,lower Himalayas

The metamorphic rocks of the Jutogh Series around Simla, structurally overlying the less metamorphosed rock groups along a thrust contact, have been involved in three phases of deformation and two episodes of metamorphism. The first metamorphism is in the albite-epidote-amphibolite facies in a major part of the area, reaching the amphibolite facies locally in the central part. This metamorphism is late-to post-kinematic with reference to the F ₁ movement, the thermal peak having been reached in a post-F ₁ pre-F ₂ static phase. The second metamorphism, syn-to post-tectonic with respect to F ₂ but preceding F ₃, is generally in the greenschist facies, and only locally in the albite-epidote-amphibolite facies in the higher structural levels. Metamorphic overprinting has caused widespread retrogression and disequilibrium assemblages. As the large scale recumbent folding and thrusting of F ₁ and F ₂ phases belong to the Tertiary Himalayan orogeny, the metamorphism in the Jutogh Series could not have been Precambrian in age.     

Selection of p–y curves for the design of single laterally loaded piles

Two-dimensional finite element analysis has been used to find load–transfer relationships for translation of an infinitely long pile through undrained soil for a variety of soil-constitutive models. It has been shown that these load–transfer curves can be used as p–y curves in the analysis of single piles undergoing lateral pile head loading in undrained soils with non-linear stress–strain laws. Lateral pile response deduced from 2-D analysis input to the subgrade reaction method has been compared to the behaviour of a single pile analysed using three-dimensional finite element analysis. Good agreement between the two methods for non-linear soils suggests that the 2-D analysis may form a useful design method for calculation of p–y curves. Copyright © 1999 John Wiley & Sons, Ltd.