validation of models and empirical equations to estimate deformations in jointed rock through the monitoring of a 40 storey tower foundation abstract there is a pressing need in rock mechanics for the calculation of deformations and stresses of structures in rock with this aim the rock mass modulus must be estimated and a model chosen to perform the calculations monitoring the foundation of twin towers in tenerife island has allowed validating both the rock mass modulus estimated from empirical equations and the model in this paper only the second tower tower n with a structural height of 137 4 m above foundation has been studied because the first tower had been previously presented by justo et al int j rock mech min sci 2006 43 267 81 the foundations of both towers are supported by jointed vesicular and weathered basalt and scoria the parameters have been deduced from the simple empirical equations proposed by several authors as a function of geological strength index gsi or rock mass rating rmr three dimensional elastic and advanced elasto plastic finite element fe programs have permitted calculation of the displacements of tower n the stresses in the slab and the factor of safety fos of the excavation the installation of rod extensometers at different depths below the slab has permitted comparison between measured and calculated displacements good fit has been obtained in this type of rock these results increase our confidence in the use of classification schemes to estimate the deformations in jointed rock in construction processes that involve unloading reloading it is important to use a material model that considers these processes the use of advanced elasto plastic methods increases the calculated settlements even if there are no failure points as the pre consolidation stress and the mobilized angle reached during the excavation phase are exceeded at many points during the loading phase tension cut off points also increase deformations with respect to linear elastic behaviour the hardening soil model improves fit between measured and calculated settlements as well

predicting the deformation moduli of rock masses abstract predictive empirical models for the mechanical properties of rock masses have been used in rock engineering because direct measurement of the properties is difficult due to the presence of discontinuities such empirical models are open to improvement because they are based on collected data the purposes of the present study are to assess the existing empirical equations and to develop a new empirical approach for this reason in the first stage of the study the prediction performance of the existing models proposed for predicting the deformation modulus of rock masses were evaluated statistically by using a database including 115 data values obtained from in situ plate loading and dilatometer tests a new empirical approach with higher prediction capacity than the existing empirical models was developed in the subsequent stage of the study the new empirical model considers the modulus ratio of intact rock e i ucs rock quality designation rqd and weathering degree wd although data obtained from very weak and weak rock masses were included in the development of the new empirical equation the type of rocks employed in the study were limited therefore a crosscheck between the new empirical equation and previous empirical approaches should be performed in the design stage

method for estimating the deformability of heavily jointed rock masses determination of the deformability of jointed rock masses is an important and challenging task in rock mechanics and rock engineering in this paper simple expressions are derived for estimating the equivalent isotropic deformation properties of heavily jointed rock masses using the methodology of equivalent continuum approach the derived expressions are compared with two analytical relations in the literature and the field test data relating rock quality designation rqd and deformation modulus ratio em er where em and er are the deformation modulus of the rock mass and the intact rock respectively the derived expressions are in reasonable agreement with the existing analytical relations in the literature and satisfactorily predict the range of the field rqd versus modulus ratio em er data finally two examples are presented to demonstrate the application of the derived expressions by applying them to estimate the deformation modulus of jointed rock mass at two sites the results of the paper

full glacial late glacial palaeoclimate of the southern andes evidence from pollen beetle and glacial records palaeoecological studies carried out in the chilean lake district and chilotan archipelago 41 43 s record full glacial and late glacial pollen assemblages beginning just after 21000 and beetle assemblages after 18000 both sets extending until 10000 14c yr bp pollen records indicate that subantarctic parkland the vegetation of the early millennia of record changed after about 14000 yr bp to become open woodland and later north patagonian evergreen forest assemblages of plants and beetles responding more or less in unison to a strong rise in temperature 6 c behaved in accord at around 14000 until 13000 12500 yr bp the beetle fauna displaying a marked increase in obligate forest types during full glacial conditions 17400 16100 and 15300 and 14400 yr bp and in the late glacial interval after about 13000 yr bp however climate evidently coerced populations dissimilarly the pollen sequence showing an increase in plant taxa indicative of colder climate whereas the beetle fauna underwent little or no variation contrasting climate modes implied by plants and beetles may be attributed to differential responses to apparent low order temperature changes 2 3 c

in situ measurements of rock mass deformability using fiber bragg grating strain gauges abstract in order to examine how the mechanical properties of a rock mass vary from the centimeter to meter scale we performed two field point loading tests 89 kn and 890 kn to determine the in situ modulus of deformation of a rock mass the experimental setup is analogous to plate jacking type tests but instead using a point load the experiments were done in the poorman formation on the 4100 level 1250 m underground of the sanford underground research facility surf at the site of the former homestake gold mine in lead sd for comparison with in situ values we also conducted laboratory mechanical tests and used two geotechnical classification systems to evaluate rock stiffness the in situ modulus of deformation increases with depth into the rock mass this increase in stiffness is a result of the differences in mechanical properties due to the effect of excavation of the underground space near the surface 0 1 2 m depth the rock is softest due to induced fractures and damage from blasting beyond this damaged zone is the stress relief zone 1 2 1 5 m depth where open joint sets affect rock stiffness and beyond that lies the undisturbed zone 1 5 m depth where the rock is the stiffest if done properly in situ measurements of rock stiffness are a valuable tool to fully characterize the gradient in stiffness of a rock mass which laboratory tests or geotechnical classification systems do not fully capture

an example of estimating rock mass deformation around an underground opening using numerical modeling abstract in rock engineering rock strength is regarded as an important rock mass parameter and it is widely estimated using the uniaxial compressive strength ucs test a ucs test in laboratory requires sampling and preparation of core samples which necessitates time consuming and expensive studies furthermore preparation of cores is almost impossible for a weak rock material taken from foliated laminated or thinly bedded rock masses of low rock quality designation rqd values 0 20 in this case determination of ucs by laboratory test may be impossible in compliance with isrm or astm standards to overcome this difficulty indirect tests such as point load index pli schmidt hammer sh rebound number tests are often employed to predict the ucs however indirect tests are likely to yield ucs values with large standard deviations depending on the geological origin of the rock mass the block punch index bpi has recently been developed to overcome the drawbacks of ucs and indirect tests and to minimize the errors arisen from the structural deficiencies and large standard deviations in this study determination of rock mass behavior in laminated foliated bornova melange yellowish brown flysch and grayish black flysch and well jointed yamanlar volcanics altindag formation where the second phase of the izmir metro tunnels was excavated is aimed the bpi ratings were directly used in rmr calculations and indirectly used to estimate the ucs values of rock materials then the obtained results were input into numerical models along with the rock mass strength ucs rm and deformation modulus of rock mass e rm the results obtained from the numerical models agreed with that obtained results from inner tunnel convergence and ground settlement measurements

high resolution marine record of climatic change in mid latitude chile during the last 28 000 years based on terrigenous sediment parameters abstract marine sediment cores from the continental slope off mid latitude chile 33 s were studied with regard to grain size distributions and clay mineral composition the data provide a 28 000 yr14c accelerator mass spectrometry dated record of variations in the terrigenous sediment supply reflecting modifications of weathering conditions and sediment source areas in the continental hinterland these variations can be interpreted in terms of the paleoclimatic evolution of mid latitude chile and are compared to existing terrestrial records glacial climates 28 000 18 000 cal yr b p were generally cold humid with a cold semiarid interval between 26 000 and 22 000 cal yr b p the deglaciation was characterized by a trend toward more arid conditions during the middle holocene 8000 4000 cal yr b p comparatively stable climatic conditions prevailed with increased aridity in the coastal range the late holocene 4000 0 cal yr b p was marked by more variable paleoclimates with generally more humid conditions variations of rainfall in mid latitude chile are most likely controlled by shifts of the latitudinal position of the southern westerlies compared to the holocene the southern westerly wind belt was located significantly farther north during the last glacial maximum less important variations of the latitudinal position of the southern westerlies also occurred on shorter time scales

laboratory thermal emission spectroscopy of shocked basalt from lonar crater india and implications for mars orbital and sample data 1 whereas the thermal infrared tir spectra of specific minerals and or igneous and metamorphic rocks have been compared to data of the martian surface tir data of the impactite products of the shock metamorphism of basalt have not been examined in detail the effects of shock on the thermal infrared spectrum of deccan basalt are described here sample collection at lonar crater india yielded four classes of shocked basalt classes 1 2 4 and 5 spectral features attributed to labradorite in tir spectrum of unshocked deccan basalt are absent in the spectrum of class 2 shocked basalt petrography confirms that labradorite has been replaced by diaplectic glass maskelynite the tir spectrum of class 2 shocked basalt is nearly identical to that of the los angeles shergottite the addition of experimentally shocked plagioclase feldspars as tir end members improves fits and lowers rms errors for the deconvolution of the tir spectrum of the maskelynite bearing impactite and the correct mineralogy is chosen to within 5 class 4 shocked basalt contains vesiculated plagioclase glass due to more heat and highly fractured augites two class 5 spectral types have primary si o stretching vibrations at lower wave numbers than si and si k glass end members commonly used in analyses of tir data agreeing with lower sio2 abundances 50 determined from two techniques at least three differences in spectral features exist between the two class 5 spectral types that we attribute to incomplete melting in the class 5a samples based on comparison to the class 4 spectrum these samples and their tir spectra represent excellent analogs for martian shocked basalt and new lithologic end members for use in spectral libraries used to analyze tir data from mars

the paleoclimatic interpretation of clay minerals in sediments a review abstract the application of paleoclimatic interpretation to clay minerals from continental and marine sediments is reviewed and the advantages of this method are indicated levels relatively rich in chlorite illite palygorskite and quartz are interpreted as corresponding to relatively dry periods while more humid periods lead to more intensive weathering and consequently to the dominance of clay minerals more advanced in the relative stability scale such as kaolinite smectite is taken to indicate a climate with contrasting seasons and a pronounced dry season using this and similar schemes the paleoclimates of areas adjoining the mediterranean basin north sea north atlantic southern arctic equatorial and north west pacific and north phillipine sea are reconstructed clay minerals in sediments particularly marine sediments can be useful indicators of paleoclimatic conditions while they do not produce direct indications of climatic parameters they provide integrated records of overall climatic impact occasionally they may be superior to the more conventional paleoclimatic methods such as pollen or oxygen isotope analysis the limitations imposed on the paleoclimatic interpretation of clay minerals in sediments are discussed on the basis of examples the distinction between authigenic and detrital clay minerals is shown to be problematic particularly with regard to smectite the relationship between climatic parameters and clay mineral formation is complicated by the intervention of extra climatic factors such as topography geomorphology lithology and time post depositional diagenetic changes may not be recognized differentiation during transport due to size sorting or differential flocculation may overlap climate induced differentiation the association of clay mineral assemblages with specific source areas presents difficulties due to dispersal pathways that are affected by type of transport agency i e water ice or wind transport agencies are not constant with time by an interdisciplinary approach with the paleoclimatic information derived from clay minerals being correlated with that obtained from the analysis of microfossils and oxygen isotope data many of these limitations can be overcome

poisson s ratio values for rocks abstract compared to other basic mechanical properties of rocks poisson s ratio is an elastic constant of which the significance is generally underrated yet in rock mechanics there is a considerable number of diverse areas which require a prior knowledge or estimation of the value of poisson s ratio this paper examines the values and applications of poisson s ratio in rock mechanics following an historical account of the initial controversy whether it was a material constant or not the effects of poisson s ratio in the elastic deformation of materials intact rocks and rock masses are briefly reviewed also the reported values of poisson s ratio for some elements materials and minerals are compiled while typical ranges of values are presented for some rocks and granular soils finally poisson s ratio classifications are recommended for isotropic intact rocks

sedimentation in the chile trench petrofacies and provenance abstract the chile trench study area extends over 2 000 km along the andean continental margin from 23 s to 42 s latitude the qfl composition of chile trench sands encompasses the average compositions of modern sands from strike slip continental arc oceanic backarc and oceanic forearc types of active margins valloni and maynard 1981 and spans the complete spectrum from dissected to undissected magmatic arc settings dickinson et al 1983 trench sands along north chile central chile and the glaciated archipelago of south chile are derived from a more plutonic source region or dissected magmatic arc these sands exhibit abnormally low lithic and calcic plagioclase content but high quartz and alkali feldspar in central chile the plutonic provenance is correlated with an ab ence of quaternary volcanism along the chilean archipelago pleistocene glaciation has carved into the magmatic roots of the andes effecting arc dissection in spite of active volcanism in arid north chile the volcanic debris of the high cordillera is trapped onshore in longitudinal forearc basins allowing an exaggerated contribution from crystalline rocks of the coast range the light and heavy mineral and lithic composition of trench sands is described by four ideal petrologic assemblages isolated by q mode factor analysis the basic magmatic arc petrofacies volcanic lithics calcic plagioclase olivine clinopyroxene and orthopyroxene the most chemically unstable and least differentiated assemblage is derived exclusively from basalts and basaltic andesites in the quaternary volcanic arc of south chile the acidic magmatic arc petrofacies volcanic lithics alkali feldspar biotite hornblende and magnetite is derived from andesitic to rhyolitic volcanics and granodioritic plutons emplaced during various mesozoic and cenozoic magmatic episodes in the history of the andean margin the metamorphic magmatic arc petrofacies mica alkali feldspar hlorite actinolite epidote and blue green hornblende is derived from ferromagnesian rocks altered to the greenschist facies in the basal marine section of the andean eugeosyncline and in the paleozoic basement the cratonic block petrofacies quartz and the accessory minerals andalusite garnet and tourmaline is derived from mature platform sediments late stage granitic intrusions and high grade regional metamorphics associated with the south american craton it is most prominent along northern chile where the continental crust is thickest and presumably truncated by subduction erosion actual petrofacies in the chile trench are typically mixtures of the four ideal petrofacies their compositions can be related to 1 the lithology and erodibility of the source terranes 2 the distribution and composition of modern arc volcanism 3 the prevailing climate in the provenance region and 4 the structure and morphology of the continental margin and trench in many cases contemporary volcanism inundates and dominates the petrologic assemblage diluting contributions from all other source rock types and forming a low diversity petrofacies at high latitudes where glaciation was extensive a variety of source rock terranes were actively denuded and petrofacies of high diversity were deposited in the adjacent trench the linear frequency of sediment supply points along the base of the continental slope controls the spatial heterogeneity of petrofacies on the depositional surface in the trench basin the most homogenous petrofacies derived from major submarine canyon systems and extensive subaerial drainage basins may extend hundreds of kilometers along margin due to axial transport processes within the trench

late quaternary precessional cycles of terrigenous sediment input off the norte chico chile 27 5 s and palaeoclimatic implications abstract the palaeoclimatic conditions during the last glacial maximum lgm of southern south america and especially latitudinal shifts of the southern westerly wind belt are still discussed controversially longer palaeoclimatic records covering the late quaternary are rare a particularly sensitive area to late quaternary climatic changes is the norte chico northern chile because of its extreme climatic gradients small shifts of the present climatic zonation could cause significant variations of the terrestrial sedimentary environment which would be recorded in marine terrigenous sediments to unveil the history of shifting climatic zones in northern chile we present a sedimentological study of a marine sediment core geob 3375 1 from the continental slope off the norte chico 27 5 s sedimentological investigations include bulk and silt grain size determinations by sieving atterberg separation and detailed sedigraph analyses additionally clay mineralogical parameters were obtained by x ray diffraction methods the 14c dated core covering the time span from approximately 10 000 to 120 000 cal yr b p consists of hemipelagic sediments terrigenous sedimentological parameters reveal a strong cyclicity which is interpreted in terms of variations of sediment provenance modifications of the terrestrial weathering regimes and modes of sediment input to the ocean these interpretations imply cyclic variations between comparatively arid climates and more humid conditions with seasonal precipitation for northern chile 27 5 s through the late quaternary the cyclicity of the terrigenous sediment parameters is strongly dominated by precessional cycles for the palaeoclimatic signal this means that more humid conditions coincide with maxima of the precession index as e g during the lgm higher seasonal precipitation for this part of chile is most likely derived from frontal winter rain of the southern westerlies thus the data presented here favour not only an equatorward shift of this atmospheric circulation system during the lgm but also precession controlled latitudinal movements throughout the late quaternary precessional forcing of latitudinal movements of the westerly atmospheric circulation system may be conceivable through teleconnections to the northern hemisphere monsoonal system in the atlantic ocean region

determination of deformation modulus in a weak rock mass by using menard pressuremeter abstract the deformation modulus of heavily jointed andesitic rock mass was investigated by using 41 menard pressuremeter test results and geotechnical information obtained from seven geotechnical boreholes the geotechnical borehole logs and laboratory test results provided by a mining company were used for the assessment of rock mass characterization the log and the test results were taken into account in the rock mass classification work the well known empirical equations were employed to predict the deformation modulus of the rock mass the predictions and the pressuremeter test results were compared and their performance indicators were presented non linear multiple regression methods were used for predictive modelling of the deformation modulus of the rock mass by considering the available data rock quality designation rqd discontinuity condition rating dc of the rock mass rating rmr system and uniaxial compressive strength of the intact rock ci were taken into consideration as input parameters in four new prediction equations to be used for determination of deformation modulus one more equation was proposed by the addition of the depth as a predictive parameter the influence of the depth and vertical to horizontal stress ratio k on the deformation modulus was preliminarily examined by using finite element modelling initially the rock mass was assumed to be an isotropic elastic brittle plastic medium later on the rock mass was modelled as a discontinuum by imposing a discrete fracture network dfn keeping all of the mechanical properties constant different depth and k parameters were applied to the pressuremeter models no influence of the depth and k on the deformation modulus was observed for the isotropic medium while the depth contributed to an increase in the modulus in the anisotropic discontinuum analysis the numerical modelling findings constituted a basis for the inclusion of the depth parameter into the new predictions

determination of geomechanical properties and collapse potential of a caliche by in situ and laboratory tests working in complex grounds have always been difficult for engineering geologists because of the heterogenous nature of such geo materials which results in different behaviors under stresses the caliches outcropping in the adana basin and its close vicinity are selected as the study material because of their highly complex nature and also understanding their mechanical behaviour and collapse potential is too difficult although their aerial extent is large in the region for this reason investigation of the collapse potential and mechanical behaviour of the caliches by applying new approaches besides the conventional in situ and laboratory tests is the purpose of the study the study includes five main stages such as measurements of caliche profiles in situ tests plate loading sampling shooting photographs for photoanalyses and laboratory studies four different levels such as hard pan silty sandy layer gravelly blocky layer and clayey level are described for the caliches employed the hard pan level is a weak rock with an average uniaxial compressive strength of 11 89 mpa while the others have typical soil characteristics a series of plate loading tests are applied on the blocky gravelly level of the caliche to determine the modulus of elasticity the modulus of elasticity and the allowable bearing capacity are determined between 28 6 65 3 and 1 5 2 0 mpa respectively to determine the grain size distribution curve in addition to sieve analyses a photoanalysis technique is also applied and a combination procedure between the results from both sieve analyses and photoanalyses is introduced and the grain size curves for the blocky gravelly level of the caliche are obtained according to the results of collapse potential index tests performed on the samples collected from 20 locations of the study area the soft pan level of the caliche has slight to moderate degree of collapse indices in the final stage various simple and statistically meaningful empirical equations are proposed for the indirect determination of the collapse index by employing simple paramateres

indirect determination of the modulus of deformation of rock masses based on the gsi system today as a result of the increase in the number of large tunnel constructions and underground excavations required for civil engineering and waste disposal and the operation of deep open pit mines determination of rock mass properties has become one of the most important stages in design and construction for rock engineering when rocks and rock masses are classified for geotechnical purposes this needs to be on the basis of strength or static modulus of deformation to give an indication of their stability or deformational response in addition the strength and modulus of deformation are the necessary input parameters of the rock masses to be utilized by numerical methods the modulus of elasticity of the rock material is undoubtly the geomechanical parameter that best represents the mechanical behaviour of rock material a similar conclusion can also be made for rock masses however the modulus of deformation of rock masses should be determined in situ by carrying out special tests which normally implies considerable costs and operational difficulties because of such difficulties the determination of the modulus of deformation of the rock masses continues to attract the attention of rock engineers and engineering geologists given the importance of having the value of the modulus of deformation available and at the same time the operational and economical difficulties mentioned above many researchers mentioned below were led to consider several cost effective and not too time consuming indirect procedures that can provide information on the modulus of deformation these attempts

predictive model for uniaxial compressive strength for grade iii granitic rocks from macao abstract determination of the uniaxial compressive strength ucs of rocks is an important task for rock and geotechnical engineering applications direct measurement is expensive time consuming and even infeasible in some circumstances due to the difficulty in obtaining core samples therefore empirical models are particularly favorable to engineers especially in the preliminary design stage however there is a lack of predictive ucs model for granite of weathering grade iii but it is well recognized to be crucial to the design of pile foundations on granitic bedrocks in this study a reliable predictive model will be developed under the bayesian framework an extensive experimental program was performed in this study to construct a comprehensive database of the measurements of uniaxial compressive strength point load index schmidt rebound hammer value p wave velocity effective porosity specific gravity and dry density it has been proven that the proposed model possesses satisfactory predictive performance

a comparative study of the determination of rock mass deformation modulus by using different empirical approaches abstract the increase in rock engineering projects over the last decade has made an increase in the importance of the determination of the rock mass parameters although properties of rock material are usually determined at laboratory it can also be determined by special in situ tests these in situ tests are both expensive and time consuming therefore empirical equations are developed to estimate rock mass properties by several researchers in numerical modelling rock mass properties are important furthermore controlling the results of models making back analysis and taking the feedback are very important comparison of different empirical equations of deformation modulus of rock mass suggested by different researchers by using field displacement measurements and numerical modelling results is aimed in this study

a late holocene 2600 bp glacial advance in the south central andes 29 s northern chile radiocarbon dates and relative ages of soils on moraines provide evidence of a substantial late holocene 2600 bp readvance of glaciers in the western part of the arid andes at 29 s the glacier in the encierro valley northern chile reached about 60 of its late pleistocene extent the equilibrium line altitude ela during this advance remained between 4250 and 4500 m which is above the modern 0 c isotherm of the free atmosphere during summer it is suggested that given the specific climate at high elevations in the extremely arid andes a substantial increase in effective moisture is sufficient to explain this advance whereas no significant temperature depression was needed this compares favourably with the regional late holocene climatic history when lake levels were higher and effective moisture greater than today between 3000 and 1800 bp judging from regional palaeodata we suggest that this late holocene humid spell was most likely related to increased westerly moisture sources from the pacific

the foundation of a 40 storey tower in jointed basalt abstract a 132 70 m high tower above foundation has been successfully completed at tenerife island the foundation of the tower a 2 m thick reinforced concrete slab is supported by jointed vesicular and weathered basalt and scoria a three dimensional elastic finite element program has permitted to calculate the displacements of the tower and the stresses in the slab the installation of rod extensometers at different depths below the slab and clinometers at the lower basement has provided comparison between measured and calculated displacements and the estimation of in situ deformation moduli a first stage prediction before construction has allowed establishment of an upper limit based upon pressuremeter modulus and a lower limit based upon bieniawski s equation the geomechanics classification in rock engineering applications in proceedings of the fourth cong isrm congress montreux vol 2 1979 p 41 48 of the settlements of the tower slab the geometric mean of these values comes close to the measured settlement the moduli deduced from the simple empirical equation proposed by gokceoglu et al predicting the deformation modulus of rock masses a comparative study int j rock mech min sci 2003 40 701 10 and hoek and brown practical estimates of rock mass strength int j rock mech min sci 1997 40 701 10 as a function of gsi provide a good fit with the measured settlements in this type of rock a good correlation is also obtained with the empirical equation presented by verman et al effect of tunnel depth on modulus of deformation of rock mass rock mech rock eng 1997 30 3 121 7 that incorporates the influence of the confining stress in the deformation modulus

clay mineral distribution in surface sediments of the south atlantic sources transport and relation to oceanography abstract surface samples mostly from abyssal sediments of the south atlantic from parts of the equatorial atlantic and of the antarctic ocean were investigated for clay content and clay mineral composition maps of relative clay mineral content were compiled which improve previous maps by showing more details especially at high latitudes large scale relations regarding the origin and transport paths of detrital clay are revealed high smectite concentrations are observed in abyssal regions primarily derived from southernmost south america and from minor sources in southwest africa near submarine volcanoes of the antarctic ocean south sandwich bouvet island smectite contents exhibit distinct maxima which is ascribed to the weathering of altered basalts and volcanic glasses the illite distribution can be subdivided into five major zones including two maxima revealing both south african and antarctic sources a particularly high amount of mg and fe rich illites are observed close to east antarctica they are derived from biotite bearing crystalline rocks and transported to the west by the east antarctic coastal current chiorite and well crystallized dioctaedral illite are typical minerals enriched within the subantarctic and polarfrontal zone but of minor importance off east antarctica kaolinite dominates the clay mineral assemblage at low latitudes where the continental source rocks west africa brazil are mainly affected by intensive chemical weathering surprisingly a slight increase of kaolinite is observed in the enderby basin and near the filchner ronne ice shelf the investigated area can be subdivided into ten large scale clay facies zones with characteristic possible source regions and transport paths clay mineral assemblages of the largest part of the south atlantic especially of the western basins are dominated by chlorite and illite derived from the antarctic peninsula and southernmost south america and supported by advection within the circumantarctic deep water flow in contrast the east antarctic provinces are relatively small assemblages of the eastern basins north of 30 s are strongly influenced by african sources controlled by weathering regimes on land and by a complex interaction of wind river and deep ocean transport the strong gradient in clay mineral composition at the brazilian slope indicate a relatively low contribution of tropically derived assemblages to the western basins

southern westerlies during the holocene deduced from geomorphological and pedological studies in the norte chico northern chile 27 33 s abstract in the norte chico precipitation is controlled by atmospheric perturbations and frontal systems associated with the belt of westerly wind circulation the holocene climatic history of the region can be reconstructed from geomorphic and pedologic investigations in comparison to modern climatic conditions increased influence of the westerlies is deduced for the time periods prior to 7300 yr b p between 5000 3700 yr b p 3000 1800 yr b p and around 270 yr b p it remains uncertain whether the increased influence of the westerlies was the consequence of northward shifts of the westerlies as a whole of a meridional expansion of the westerly belt or only of intensity changes of the atmospheric dynamics almost synchronous with changes in the westerlies the coastal fogs in the region were apparently reduced or the fog belt in the coastal range was elevated probably due to a weakened upwelling and warmer water conditions in the eastern pacific in general the climate of the norte chico has become more variable since 5000 yr b p especially since 3000 yr b p with frequent changes of the geoecological conditions

ice age vegetation and climate of subtropical chile abstract vegetation and climate of subtropical chile over the past 50 000 yr are reconstructed from pollen spores and other microfossils contained in a 10 7 m section of lacustrine deposits of laguna de tagua tagua 34 30 s 71 10 w controlled by 14 radiocarbon age determinations five pollen assemblages covering stratigraphic zones in the section represent plants on the upland and species inhabiting the lake basin surface pollen spectra from 58 stations approximately 30 40 s form an adjunct for interpreting past vegetation and climate from the fossil record temperature semi humid woodland of southern beech nothofagus dombeyi type and podocarp prumnopitys andina was apparently established about laguna de tagua tagua during the pleistocene contrasting existing semi arid broad sclerophyllous vegetation the woodland was extensive about the lake at the time of the last glacial maximum 25 000 14 000 yr b p and earlier 43 000 34 000 yr b p pollen from the families chenopodiaceae and amaranthaceae which characterize intervals of the pleistocene centered around 33 000 and 43 000 yr b p and the holocene suggests intervening episodes of relative aridity lake level fluctuations appear to follow the late quaternary climatic pattern implied by pollen assemblage data water in the lake was relatively high during development of southern beech podocarp woodland whereas during intervals of chenopod amaranth dominance lake levels were comparatively low excess precipitation over evaporation which during the pleistocene favored development of woodland of beech and podocarp is attributed to greater storm frequency conditions were apparently governed by strengthening of atmospheric circulation in the belt of southern westerly winds in the late glacial the temperate and more humid ice age climate with limited seasonality underwent transition to a subtropical semi arid mediterranean type that identifies the postglacial fluctuations in intensity of the southern westerlies marked by latitudinal movement of the polar front can account for past vegetation changes at laguna de tagua tagua

estimating the deformation modulus of rock masses a comparative study although the modulus of deformation of rock masses has crucial importance for geotechnical projects such as tunnels and dams the determination of this parameter by in situ tests requires considerable costs and involves difficult operational processes for this reason empirical equations for the indirect estimation of the modulus of deformation are an interesting issue for rock engineers and engineering geologists this study includes assessment of the prediction performances of some existing empirical equations using in situ plate loading test data and rock mass properties producing an empirical equation depending on the new data construction of a fuzzy inference system for the estimation of modulus of deformation and making a comparison between results obtained from the empirical equations and fuzzy inference system a series of calculations and statistical analyses were undertaken it is concluded that the performance of the empirical equations and fuzzy inference system obtained in this study is satisfactory however the prediction models developed in this study are limited by the number of the data used and the rock types employed for these reasons a cross check should be performed before using these prediction models for design purposes

an empirical method for determining the mechanical properties of jointed rock mass using drilling energy abstract characterization of jointed rock masses and evaluation of their mechanical properties are challenging tasks in rock engineering this paper presents an experimental investigation of the response characteristics of drilling energy to the discontinuity of rock mass using a drilling method the linear relationship between the drilling energy and discontinuity frequency is revealed which only depends on the rock type and is independent of calculation units a new empirical method for determining the rock quality designation rqd versus the variation of drilling energy is proposed based on the discontinuity frequency comparison between the prediction and in situ investigation results demonstrates that the rqd can be estimated from this empirical method the em er modulus ratio and cm c strength ratio versus rqd relations are modified for the determination of rock mass strength and deformation modulus in order to consider the continuous variation of em er and cm c with the model parameter which is related to the drilling energy and modulus of elasticity of intact rock and the variation of drilling energy for rock mass the results show that the modified em er cm c versus rqd relations can give proper values compared with the field test results as well as compared with the various proposed relations from rmr q and gsi the modified relations can provide a practical fast and easy to use method for the estimated rock mass strength and deformation modulus but they are only a first approximation

holocene climatic optimum in southwest africa evidence from the marine clay mineral record abstract sediment composition grain size and clay mineral record of a high resolution sediment core from the continental slope off namibia was investigated to gain information on the deposition of terrigenous matter in this part of the southwest african continental margin during the last 18 k y the depositional processes involved are fluvial input by the kunene river and eolian input from the namib and kalahari deserts each supplying characteristic mineral suites during low sea level erosion of the exposed shelf yields additional material the amount of eolian or fluvial matter depends on the strength of the transport process which is a function of aridity or humidity of the source area thus allowing paleoclimatic interpretations arid conditions prevailed during a low sea level from 18 to 15 ka and unconsolidated shelf sediment was mobilized and supplied to the slope by short distance transport by southerly winds a dramatic increase in the accumulation of terrigenous sediment is recorded from 15 to 10 ka without major changes in sediment composition which is attributed to increased runoff of the kunene river and fluvial erosion of shelf sediments this period coincides with a strengthening of the monsoonal system during a precessional minimum which is observed in numerous sites in central africa and indicates an intensified influence of the monsoon at the kunene headwaters a distinct shift in clay mineralogy towards river derived material marks a second period of increased river runoff during high sea level from 9 to 5 ka indicating maximum humidity in the source area from 6 to 5 ka this corresponds to the holocene climatic optimum observed in the arid belts of northern africa the present balance between fluvial and eolian input was reached approximately at 4 ka

modeling deformation modulus of a stratified sedimentary rock mass using neural network fuzzy inference and genetic programming abstract this paper investigates a series of experimental results and numerical simulations employed to estimate the deformation modulus of a stratified rock mass the deformation modulus of rock mass has a significant importance for some applications in engineering geology and geotechnical projects including foundation slope and tunnel designs deformation modulus of a rock mass can be determined using large scale in situ tests this large scale sophisticated in situ testing equipments are sometimes difficult to install plus time consuming to be employed in the field therefore this study aims to estimate indirectly the deformation modulus values via empirical methods such as the neural network neuro fuzzy and genetic programming approaches a series of analyses have been developed for correlating various relationships between the deformation modulus of rock mass rock mass rating rock quality designation uniaxial compressive strength and elasticity modulus of intact rock parameters the performance capacities of proposed models are assessed and found as quite satisfactory at the completion of a comparative study on the accuracy of models in the results it is seen that overall genetic programming models yielded more precise results than neural network and neuro fuzzy models