an analytical study of the sea breeze abstract in this paper we present theoretical results concerning the sea breeze intensity and its inland penetration as a function of latitude and friction we produce solutions for the spatial structure of the streamfunction and momentum components and for their line behavior in the case of a step function forcing of finite duration and in the case of periodic forcing results show that the sea breeze initially has an aspect ratio equal to unity and that earth rotation and friction aged its intensity but they are unimportant in determining its early geometry the sea breeze has a characteristic time scale which is a combination of the inertial period and the e folding time due to friction for a time larger than this characteristic time scale the inland penetration of the sea breeze is confined by a rossby deformation radius which includes a frictional effect in fact friction and inertia reduce not only the intensity but also the horizontal scale of motion at the equator the controlling parameter

deep weathering of a group of thick argillaceous limestone rocks near three gorges reservoir central china rock mass characterization is one of the most basic and important tasks in rock mechanics and engineering literature review indicates that although there are many publications available on weathered rocks there are few reports in english on weathered argillaceous limestone rocks and their chemical and mechanical properties this paper presents a case study of characterizing a group of highly weathered thick argillaceous limestone rocks most importantly they can be easily and quickly decomposed into soils after they are exposed due to excavation consequently they would substantially lose their mechanical strengths geohazards such as landslides and sinkholes could occur in uncovered highly weathered argillaceous limestone rocks the problematic weathered rocks were found during the development of a new town in upper mountains above the three gorges reservoir on yangtze river in central china in the past 20 years the factual data are presented on the changes of chemical compositions and mechanical properties of the weathered argillaceous limestone rocks due to chemical weathering some empirical correlations are given to quantify the changes in their uniaxial compressive strength and deformation moduli in terms of their contents of calcium carbonate the data and findings presented in the paper can be useful to future urban development in geologically poor mountainous environments occupied by highly weathered argillaceous limestone rocks in the world

proterozoic stratigraphy and tectonic history of the georgetown inlier northeastern queensland the proterozoic sequence in the central part of the georgetown inlier has been divided into the etheridge langlovale croydon and inorunie groups the early to middle proterozoic etheridge group consists of shallow water fine grained clastic metasedimentary rocks and minor basaltic lavas and related dolerite intrusions it was deposited in a uniformly subsiding basin in a continental setting sometime between 2400 and 1570 ma it was first deformed at 1570 ma d1 and again at 1470 ma d2 by major folding events accompanied by low to intermediate pressure metamorphism mainly in the greenschist and amphibolite facies but ranging into the granulite facies in places during d2 the grade of metamorphism increases from west to east extensive s type plutonic magmatism accompanied d2 in the west the langlovale group a fluviatile to marine pro deltaic facies post dates d1 and was deposited before d2 it is moderately folded but not regionally metamorphosed post orogenic magmatism also s type is represented in the western part of the inlier by the subaerial felsic ignimbrite of the croydon volcanic group and related subvolcanic granitoids the volcanic rocks are overlaim by the fluviatile inorunie group which is of uncertain age neither the croydon volcanic group nor the inorunie group is appreciably deformed or metamorphosed in the eastern quarter of the inlier a largely metavolcanic andesitic to felsic sequence may be an allochthonous terrain of early palaeozoic age but it could be proterozoic known proterozoic rocks thought to have been thrust over this sequence crop out on the eastern edge of the inlier they are the halls reward metamorphics and maficultramafic rocks including the boiler gully complex their relationship to the etheridge group is uncertain convective mantle upwelling could account for the extension of the continental crust which allowed deposition of the etheridge group no rifting is apparent and only the sag phase of the model of etheridge et al may be represented underplating of the crust could account for the metamorphism and felsic magma generation during the middle proterozoic the etheridge group shows characteristics of both tectonostratigraphic cycles recognized elsewhere in nothern australia and without better radiometric control correlation is difficult

quantitative assessment of weathering degree of the touzhai rock avalanche deposit in southwest china abstract weathering is one of the main preparatory causal factors for rock avalanche events and weathering assessment of involved materials can refine understanding of geomorphic processes of this class the weathering degree of the deposit of the touzhai basalt rock avalanche in china is quantitatively evaluated herein through an integrated geochemical analysis coupled with meso and micro scopic examination of fragments which can help to understand the inhomogeneity of weathering in rock slopes the clasts of 12 size classes of the debris making up the deposit ranging from meter sized boulder to fines of

engineering and geological characteristics of granite weathering profiles in south china granite weathering profiles are widely distributed in south china their engineering and geological characteristics are major geotechnical subjects that are important in the design and construction of civil engineering projects this paper presents a summary of the weathering characteristics and zoning of granite weathering profiles in south china and discusses their engineering and geological properties a five grade scheme has been adopted in the zoning of a granite weathering profile studies have shown that the completely weathered granites cwg in south china have the following characteristics low moisture content low to medium plasticity w l 22 5 39 0 i p 6 5 11 8 medium void ratio 0 36 1 29 weak shrinkage and medium compressibility a 1 2 0 24 0 8 mpa 1 and high shear strength phi 20 30degrees c 20 40 kpa the cwgs are usually at a low or high plastic state and most of them are over consolidated soils a majority of the physical and mechanical properties have good statistical correlations with the degree of weathering the data presented in the paper are important in geotechnical engineering projects such as slope stability evaluation in china c 2002 elsevier science ltd all rights reserved

a new quantitative weathering classification for igneous rocks the description and classification of the rocks provide important information for geotechnical modeling in order to predict their engineering behaviors one of the most imperative parameters influencing the engineering behaviors of the rocks is the degree of weathering therefore it is evident that a realistic weathering classification is necessary mostly for establishing the geotechnical models in the engineering geology studies for this reason development of a qualitative weathering classification is the main purpose of the present study the weathering state parameter has been first created by describing the chemical and physical changes separately owing to weathering by employing the ultrasonic wave velocity in the rock material then a quantitative weathering index was introduced by combining the weathering condition and the slake durability known as the indicator of the rock soil ratio in the rock material finally this index obtained was applied on the prediction of the engineering properties of the harsit granitic rocks giresun ne turkey as a consequence of this study it has been determined that the engineering properties of the samples and the numerical index proposed could be predicted in addition the use and the limitations of the index introduced herein were discussed

geochemical sm nd isotopic characteristics and petrogenesis of paleoproterozoic mafic rocks from the georgetown inlier north queensland implications for relationship with the broken hill and mount isa eastern succession fe rich tholeiites intruded the lower etheridge group of the georgetown inlier north queensland during the late paleoproterozoic ca 1685 1640 ma emplacement of the tholeiites occurred during a prolonged period of rift related sedimentation associated with extension the tholeiites comprise two lithologically distinct units the extrusive dead horse metabasalt dhm a conformable 1000 m thick series of fine to coarse grained basalts and pillow lavas and the intrusive cobbold metadolerite cmd a multitude of sills and lesser dykes that range up to 500 m thick the dhm and cmd are comagmatic and have compositions typical of relatively evolved low k fe rich continental rift tholeiites immobile major and trace element patterns suggest that the tholeiites were derived from a depleted upper mantle source initial nd values range between 2 6 and 5 3 the parental melts evolved along a trend of increasing fe enrichment fe2o3 6 81 21 11 wt via closed system fractionation with little or no replenishment several samples show distinct ree patterns consistent with limited crustal contamination trace element and isotopic data show that the crustal contaminants were derived from the host metasediments of the lower etheridge group the age and geochemical characteristics of the etheridge group fe rich tholeiites show striking similarities to similar mafic sills in the southeastern curnamona province around broken hill in western new south wales and to basaltic lavas and dolerites of the soldiers gap group in the eastern edge of the mt isa block some 400 km west of the georgetown inlier suggesting a spatial link between these terranes during the paleoproterozoic they may have formed along a more than 2000 km segment of a ca 1685 1640 ma volcanic passive margin tectonically and magmatically akin to the modern east greenland margin

granite residual soil properties in collapsing gullies of south china spatial variations and effects on collapsing gully erosion abstract collapsing gully erosion a special erosion phenomenon in the hilly granitic regions is an important factor responsible for the deterioration of the ecological environment in southern china the granite residual soil properties tend to vary with soil depth and their spatial variations have an important impact on the formation and development of collapsing gullies here two typical granitic soil profiles in the north boundary of collapsing gully erosion in south china were selected to investigated the spatial variations of soil physicochemical hydraulic and mechanical properties along the profile and their influences on collapsing gully erosion the upper two soil layers surface soil layer and red soil layer were significantly different from the lower two soil layers sandy soil layer and detritus layer in the investigated properties the soil texture performed a large variation along the profile which might be a positive factor for the formation of secondary vertical joints faults and weak structural planes meanwhile the lower soil layers had a lower value of pl ll organic matter and iron aluminum oxides demonstrating their poor structure and vulnerability to erosion under rainfall conditions additionally the upper soil layers had a higher water holding capacity but a lower decreasing rate in the unsaturated coefficient of permeability leading to the overburdening of the lower soil layers under rainfall conditions and the low soil layers had a low shear strength which could also lead to the sliding of the gully head and sidewall especially under saturated conditions collectively the special geological structure of the granite residual soil layers plays an important role in the occurrence and development of collapsing gully erosion the data reported in this paper may facilitate a better understanding of soil mass failure on the gully head and the collapsing gullies

life cycle of a mesoscale circular gust front observed by a c band doppler radar in west africa abstracton 10 july 2006 during the special observation period sop of the african monsoon multidisciplinary analysis amma campaign a small convective system initiated over niamey and propagated westward in the vicinity of several instruments activated in the area including the massachusetts institute of technology mit c band doppler radar and the atmospheric radiation measurement arm mobile facility the system started after a typical convective development of the planetary boundary layer it grew and propagated within the scope of the radar range so that its entire life cycle is documented from the precluding shallow convection to its traveling gust front the analysis of the observations during the transitions from organized dry convection to shallow convection and from shallow convection to deep convection lends support to the significant role played by surface temperature heterogeneities and boundary layer processes in the initiation of deep convection in semiarid conditions the analysis

spatial patterns of convection in south florida abstract although they are a fairly consistent feature the sea breeze and lake breeze convergence lines and the associated convection over south florida during the summer may vary considerably from one day to the next daily radar maps indicate a few basic recurring patterns analyses of radiosonde data show significant differences corresponding to the different patterns in the local thermodynamic parameters most notably the mixing ratio changes in the synoptic scale wind field correspond closely to changes in the observed radar patterns and the local thermodynamic conditions explanation of the formation and development of the different patterns of convection is given in terms of the complex interaction between the regional synoptic peninsular and local scale circulations

the assessment of weathering stages in granites using an ec ph meter the weathering of granite encompasses a wide range extending from slightly weathered rock to saprolite to soil although many different methods are available for quantifying the amount of chemical or physical weathering in granites dissolution rate as a method for estimating the degree of chemical weathering in these rocks was not thoroughly investigated this study sought to identify a method for quantifying weathering stages in granite based on both the chemical and physical properties of the rock using the weathering profile of granites from two quarries in the chugoku region of western japan a simple dissolution experiment measured with an electrical conductivity meter for 10 min recorded the differences in dissolution rates which reflects the chemical weathering stages in granites the combination of the dissolution rate and the p wave velocity produces a diagram that gives the chemical and physical properties of the weathered rock body in a single chart

chemical weathering of monsoonal eastern china implications from major elements of topsoil major element compositions of 36 bulk samples and 41 clay samples which were obtained from 47 topsoils collected in monsoonal eastern china were investigated with conventional wet chemistry and x ray fluorescence xrf spectrometry respectively based on major element analyses the mobility of major elements and latitudinal distributions of sio2 al2o3 ratio chemical index of alteration cia chemical index of weathering ciw and weathering index of parker wip were analyzed meanwhile the suitability of these chemical weathering indices to topsoils in monsoonal eastern china and its controls were discussed these investigations indicate that na k ca mg and si are relatively depleted while mn p fe and ti are relatively enriched in topsoils of the study area by comparison with their contents in the upper continent crust ucc and that alkali metal na k and alkaline earth metal ca mg elements are generally easier to be depleted from their parent materials than other major elements during chemical weathering the latitudinal distributions of cia ciw and wip show that they are suitable to both bulk and clay samples but sio2 al2o3 is only suitable to clay samples not suitable in bulk ones all these investigations indicate a significant dependence of grain size in major element abundance and latitudinal distributions of sio2 al2o3 cia ciw and wip but parent rock type has little effect on them except its impact on the latitudinal distribution of wip in clay samples the significant grain size dependence probably indicates the presence of unaltered minerals in bulk samples thus we suggest that clay samples are more suitable to investigating chemical weathering of sediments on continents than bulk samples the trivial effect of parent rock type probably indicates a relatively uniform chemical weathering on various parent rocks correlation analyses indicate that climate is the dominant control of chemical weathering of topsoils in the study area and the significant latitude effect indicated by the spatial distributions of chemical weathering indices actually reflect the climate control on chemical weathering of topsoils chemical weathering indices actually reflect the integrated weathering history in the study area besides the dominant control of climate other factors like tectonics parent rock biology landform and soil depth and age might also have some effect on the chemical weathering of topsoils in the study area which needs further research c 2013 elsevier ltd all rights reserved

structural evolution of a 1 6 ga orogeny related to the final assembly of the supercontinent nuna coupling of episodic and progressive deformation

investigation of physical deterioration of malayer granitic rocks using a new weathering coefficient kr4 the main aim of this research is to find the most appropriate weathering indices among geomechanical chemical and petrographical indices to characterize malayer granitic rocks in the study area physical weathering and hydrothermal alteration are predominant degradation phenomena therefore it is necessary to distinguish between the effect of these two phenomena and chemical weathering on mineralogy as well as on geomechanical rock properties the most important evidences of hydrothermal alteration are the selective sericitization of plagioclase and the occurrence of prehnite also statistical analyses including simple and multiple linear regressions were applied to identify those indices that are most influenced on the progression of weathering based on the simple regression analysis petrographical and chemical indices do not show any good trend by increasing weathering degrees r2 0 72 finally a new quantitative weathering index kr4 has been developed regarding quick absorption index p wave velocity vp point load index is and total porosity n all the mentioned parameters can be quickly and inexpensively determined by portable laboratory instruments this new index kr4 has strongly correlated with weathering degrees r2 0 96 based on some results it seems that kr4 could be more suitable and credible to numerically evaluate the physical weathering accompanied by hydrothermal alteration processes of the studied rocks

cu au mineralisation in the curnamona province south australia a hybrid stratiform genetic model for mesoproterozoic iocg systems in australia abstract the proterozoic curnamona province lies between two of the most endowed cu bearing mineral belts on the australian continent the gawler craton which hosts the giant olympic dam iron oxide copper gold iocg system and the mount isa inlier which hosts the giant mount isa cu system and iocg belt of the eastern succession this study focuses on cu au deposits within the proterozoic rocks of the benagerie ridge magnetic complex in the central curnamona province the benagerie ridge is buried beneath neoproterozoic and phanerozoic cover sequences we use drillcore and geophysical data to determine the structural architecture and structural controls of cu au mineralisation in the benagerie ridge the portia and north portia deposits are the most significant cu au mineral deposits in the benagerie ridge and lie adjacent to an extensive regional redox boundary that separates lower magnetic units from upper non magnetic units the redox boundary is extensive throughout the curnamona province and is linked with mineralisation in the region significant chalcopyrite bornite and molybdenite occur along bedding parallel layers and shear structures these factors support a strong lithological control on cu au mineralisation at all scales deformation in the benagerie ridge involved the development of a d1 layer parallel foliation s1 which is overprinted by d2 recumbent folds and d3 upright folds the deformation history is associated with the c 1610 1580 ma olarian orogeny overprinting of d2 structures during d3 has resulted in a type 2 interference pattern which we have successfully mapped using aeromagnetic data several later phases of post olarian faults overprint f2 and f3 fold interference patterns and have resulted in the remobilisation of some of the cu au mineralisation we propose that the stratiform cu au mineralisation occurred prior to the onset of the olarian orogeny mineralisation is preserved within the thickened hinge zone of a similar type f2 fold proximal to the hinge of an overprinting f3 fold which we propose has enhanced mineralisation within the north portia deposit consequently the identification of the redox boundary within f2 folds elsewhere in the curnamona province particularly when located proximal to f3 fold hinges which place the mineralised zones into structurally favourable locations provide good targets for future mineral exploration

the effect of moist convection on thermally induced mesoscale circulations a basic understanding of the mechanisms controlling the characteristics of thermally induced mesoscale circulations rests primarily on observations and model studies of dry convection whereas the influence of moist convection on these characteristics is not well understood large eddy simulations are used to investigate the effect of moist convection on an idealized mesoscale circulation sensitivity studies show that moist convection has a significant influence on the characteristics of the mesoscale circulation we identify three distinct convective phases that influence the mesoscale circulation within the diurnal cycle firstly dry convective onset with a weak circulation and a breeze front that propagates slowly from the cold region into the warmer fluid as a result of the surface discontinuity secondly a deep convective phase where the circulation intensifies and the breeze front propagates faster and finally a precipitating phase where strong cold pools develop at the breeze front and accelerate the propagation speed further classical density current theory fails to represent the second phase and is extended using the cloud base mass flux to account for the observed effects of moist non precipitating convection on the propagation speed we demonstrate the applicability of this theory to the results from large eddy simulations identify the subtle role of cold pools on density current propagation and highlight implications for numerical weather prediction

early proterozoic magmatism in yukon canada constraints on the evolution of northwestern laurentia northwestern laurentia after cratonization at about 1 85 ga underwent a series of tectonic and magmatic events during the proterozoic that were followed by separation of laurentia from another landmass probably australia the oldest magmatic event produced the bonnet plume river intrusions bpri which intruded the wernecke supergroup as short dikes and small stocks the bpri are hydrothermally altered tholeiitic diorites gabbros and subordinate anorthositic and syenitic rocks with trace element signatures consistent with a rift origin depleted mantle model ages range from 2 29 to 2 57 ga and end values range from 0 7 to 1 7 an increasing crustal component is apparent in rocks with more evolved compositions four u pb zircon ages 1705 9 0 7 1709 4 1 4 1711 1 5 1 and 1713 6 12 7 ma indicate a paleoproterozoic age for the bpri these dates constrain the age of the wernecke supergroup to ca 1710 ma making it the oldest supracrustal succession in western laurentia e g 240 ma older than the belt supergroup of southeastern british columbia and the northwestern united states the wernecke supergroup was deposited in the first rift basin to open along the western margin of laurentia but was later inverted by the pre 1 6 ga racklan orogeny an event possibly influenced by transmission of compression from the yavapai and mazatzal orogenies in southern laurentia the neoproterozoic southwestern united states east antarctica sweat reconstruction which places australia next to northwestern laurentia is supported by linkages between paleoproterozoic and mesoproterozoic geological features in northwestern canada and australia

interpretation of a ca 1600 1580 ma metamorphic core complex in the northern gawler craton australia abstract the mount woods domain in the gawler craton south australia records a complex tectonic evolution spanning the palaeoproterozoic and mesoproterozoic the regional structural architecture is interpreted to represent a partially preserved metamorphic core complex that developed during the 1600 1580 ma hiltaba event making this one of the oldest known core complexes on earth the lower plate is preserved in the central mount woods domain which comprises the mount woods metamorphics these rocks yield a detrital zircon maximum depositional age of 1860 ma and were polydeformed and metamorphosed to upper amphibolite to granulite facies during the 1740 1690 ma kimban orogeny the upper plate comprises a younger succession the skylark metasediments deposited at 1750 ma within the upper plate sedimentary and volcanic successions of the gawler range volcanics were deposited into half graben that evolved during brittle normal faulting the skylark shear zone represents the basal detachment fault separating the upper and lower plate of the core complex the geometry of normal faults in the upper plate is consistent with ne sw extension both the upper and lower plates are intruded by 1795 1575 ma hiltaba suite granitic and mafic plutons the core complex was extensively modified during the 1570 1540 ma kararan orogeny exhumation of the western and eastern mount woods domain is indicated by new 40ar 39ar biotite cooling ages that show that rock packages in the central mount woods domain cooled past 300 c 50 c at 1560 ma which was 20 million years before equivalent cooling in the western and eastern mount woods domain exhumation was associated with activity along major syn kararan orogeny faults

time constraints on deformation and metamorphism from epma dating of monazite in the proterozoic robertson river metamorphics ne australia epma dating of monazite confirms the relative timing of a succession of foliation intersection axis trends in porphyroblasts fias and two periods of progressive metamorphism intervened by retrogression in the robertson river metamorphics ne australia a complete pressure temperature deformation time p t d t path has been deciphered involving an early clockwise p t loop followed by high temperature low pressure metamorphism successive generations of monazite were identified using microstructure and fia trends and then dated the succession of four fias trending ene wsw fia1 e w fia2 n s fia3 ne sw fia4 plus four matrix foliations s1 s4 were accompanied by three periods of garnet and two periods of staurolite growth monazite grew in response to most of these events isopleth thermobarometery using p t pseudosections in the mnnckfmash system for garnet porphyroblasts selected based on fia trends in their core reveal that pressure increased progressively from 3 4 kb at 530 550 c to 6 7 kb at 600 620 c during medium pressure temperature metamorphism this was accompanied by changing bulk shortening directions from nnw sse to n s to e w perpendicular to fias 1 2 and 3 the development of fia1 and fia2 occurred between 1655 2 2 ma and 1625 15 ma fia3 developed over 30 50 ma periods from 1625 15 ma to 1586 6 ma retrogressive metamorphism decompression and exhumation occurred over a not vert similar45 ma period further metamorphism accompanied regional granite intrusion and generated lower pressure higher temperature metamorphism during the development of fia4 nw se bulk shortening at 1542 8 ma this period possibly extended for another 30 50 ma based on the monazite ages obtained from the youngest foliations in the matrix correlation of these data with other ne australian proterozoic inliers suggests that they were all once part of a single orogen that developed from ca 1650 to 1500 ma

the influence of the characteristics of quartz and mineral deterioration on the strength of granitic dimensional stones it is important to have a thorough knowledge of the petrographic characteristics of rocks to evaluate and understand their mechanical behavior this paper deals with the influence of the texture and the mineral characteristics of nine portuguese granites employed as dimensional stones this study evaluates different mineral characteristics such as mineral deterioration grain size quartz fissuration and the contacts between quartz and others mineral groups the main differences in the studied granites were identified clarifying the relationship between the petrographic characteristics the consequences on their respective mechanical behavior were subsequently evaluated the physical and textural characteristics of quartz in the studied granites have proven to be very important for understanding the behavior of granitic rocks under compressive stress uniaxial compressive strength values are not proportional to the quartz feldspar ratio or quartz content and there is a tendency for strength to decrease with the increase in quartz this could be related to the increase in quartz quartz contacts and the decrease in the rock capacity for accommodating the deformation

magnetic parameters indicate the intensity of chemical weathering developed on igneous rocks in china abstract continental weathering plays a key role in earth surface processes by linking earth s spheres and producing material for cycling previous studies have proposed numerous weathering indices for the evaluation of chemical weathering intensity however few research efforts are devoted to the changes of sediment physical properties during weathering processes and on the correlations between weathering and mineralogical chemical alteration this study investigates mineral transformation and magnetic properties of two weathering profiles developed on granodiorite and basalt in china the notable differences in magnetic properties between the two profiles i e magnetic susceptibility percentage frequency dependent susceptibility fd anhysteretic remanent magnetization arm and saturation isothermal remnant magnetization sirm are ascribed to the combined effects of parent rock lithology and climate conditions on the formation and alteration of magnetic components during weathering pedogenesis parent rock lithology e g fe bearing basalts and relatively fe poor granites determines the initial magnetic susceptibilities warm and humid climate favors rock weathering and thus enhances the magnetic intensity whereas changes in redox conditions lead to inhomogeneous degree of chemical weathering and thus alter the spatial distribution of magnetic minerals this study further suggests that the weathering intensity in geologic profiles can be evaluated by magnetic indicators such as fd and arm sirm based on their positive correlations with the chemical index of alteration cia the research findings may shed new light on the constraints on continental weathering and detrital sediment cycling in the east asian continental margin

lithological effects in soil formation and soil slips on weathering limited slopes underlain by granitic bedrocks in japan abstract soil slips occur every few years due to heavy rains on biotite granite gb and hornblende biotite granite ghb slopes in the taga mountains ibaraki prefecture japan the occurrence density of soil slips per unit area is 2 7 times greater in the gb slopes than that in ghb slopes we examined the chemical mineral physical and mechanical properties of two soil profiles on soil slip scars in these slopes to study the effect of bedrock mineral composition on the density of soil slips for a given size of mineral grain the amount of biotite which is susceptible to chemical weathering in granitic bedrocks strongly influenced the density of soil slips in the gb slope the soil layer becomes thinner because of the smaller proportion of biotite in the bedrock this restricts the downward movement of soil water into the material below the slip plane during heavy rainfall the water surface then rises toward the slope surface above the slip plane this promotes soil slips increasing the density of soil slip scars in contrast in the ghb slope with more biotite in the bedrock the soil layer becomes thicker so that soil water moves easily into the material beneath the slip plane this limits the rise of water surface toward the slope surface above the slip plane even during heavy rainfalls there are consequently fewer soil slips and density of soil slip scars

the diurnal interaction between convection and peninsular scale forcing over south florida abstract surface wind measurements taken during the summers of 1973 and 1975 in the florida area cumulus experiments face fine mesh networks are used to calculate surface divergence on the convective scale and mesoscale examination of the daily time series of divergence averaged over a 30 km 25 km grid showed that on days with deep convective activity over and around the network a definable sequence in the network averaged surface wind divergence is observed the sequence consists of five stages persistent convergence peak convergence non divergence peak divergence and the return to a non divergent state use is made of observations of individual cases and of radar composites built around the above sequence in the network averaged divergence fields to demonstrate that a convective scale feedback mechanism consisting of outflows from previous storms triggering new growth is frequently observed during both experimental periods it is shown that the observations taken over the face 1975 network are

the use of cation packing index for characterizing the weathering degree of granitic rocks the weathering state and weatherability of rocks are highly important for engineering geology projects and the use of rocks as building stones the weathering state of rocks can be described by various chemical and petrographical weathering indices to determine weathering state of a rock considerable amount of chemical analyses is required weatherability of rocks depends on not only their mineral composition but also the number of cation replaceable with hydrogen in a mineral in this study the use of the k value cation packing index is defined as the number of cation in a mole for characterizing the degree of weathering of granitic rocks is investigated for the purpose of the study the kurtun granitic rocks are selected as the material of the study the study contains three main stages and these are field investigations laboratory studies and regression analyses during the field studies in situ weathering descriptions and sampling are carried out the samples are subjected to chemical and petrographic analyses and physical and mechanical tests at the final stage of the study a series of regression analyses between the cation packing index and other properties of the samples are performed the results show that the k value can be used as a weathering indicator when compared with the other chemical weathering indices the k value can be used as a weathering index without chemical analyses because it can be determined by mineralogical analyses

alteration characteristics of granite contact zone and treatment measures for inrush hazards during tunnel construction a case study abstract several large scale mud and water inrush events occurred during excavation of the denghuazhai tunnel at a depth of 175 m in the contact zone between geodic granite and tuff by analyzing the inrush process the characteristics of the inrush hazards such as high pressure abundant water high mud and sand content and strong destructive power were revealed in addition the inrush hazards were intermittent uncertain and sudden an intrusive contact zone between geodic granite and tuff was revealed by regional geological investigation large scale alteration occurred both in geodic granite and tuff near the contact zone petrographic analyses indicated that alteration to albite sericite and kaolinite occurred in geodic granite and alteration to quartz and montmorillonite took place in tuff gradually toward the contact zone furthermore the changes were gradational within and between various alteration grades the closer to the contact zone the higher degree of alteration the less the primary minerals including quartz k feldspar and plagioclase the more the secondary minerals such as sericite and clay minerals tests on porosity saturated water content and uniaxial compressive strength indicated that alteration led to significant deterioration of physical and mechanical properties of rocks except for silicified tuff especially for the zonal clay in the central area of contact zone the physical and mechanical properties were poor and obvious swelling disintegration and argillation were observed tunnel excavation triggered swelling disintegration and argillation of clay leading to several large scale inrush events in terms of treatment of inrush hazards first of all a comprehensive exploration method based on petrographic analyses geophysical detection and borehole drilling was established according to the alteration characteristics so as to identify the scale and composition of the altered zone the principle of consolidation before removal was adopted to deal with the inrush deposits for breach sealing and reinforcement energy release and stress reduction during tunnel construction and regular drainage during operation were achieved by dewatering measures namely drainage supplemented by sealing water drainage and solids remaining reinforcement measures including full face curtain grouting and double layer pipe sheds were adopted to reinforce and seal the highly disturbed rock and soil in advance finally technical measures including bench excavation enhancement of support stiffness and timely installation of secondary support were employed to effectively prevent large deformation in disturbed rock masses with the above measures the left and right tunnels of the denghuozhai tunnel have passed through the altered zone successfully

new weathering classifications for granitic rocks based on geomechanical parameters here we investigate the classification of weathering grade for granitic rocks from the malayer granitoid western iran using physico mechanical parameters the physical and mechanical properties of rock samples were measured across five weathering grades ranging from fresh rock to completely weathered statistical analyses including simple regression and multiple linear regression were applied to identify those physico mechanical parameters that are most influenced by the progression of weathering the parameters with significant correlations with weathering grade include strength retention index p wave velocity porosity brazilian tensile strength and point load index on the basis of the statistical results new classifications are developed these classifications can be used to predict the engineering properties of the malayer granitic rocks hamedan nw iran and should have more general application to the quantitative classification of granitic rocks in iran

comparing 1800 1600 ma accretionary and basin processes in australia and laurentia possible geographic connections in columbia abstract we focus on potential pinning points on the southern and eastern margins of australia and the southern and western margins of laurentia and interpret a convergent plate boundary along the southern margin of the proto australian continent during the palaeo to mesoproterozoic 1800 1600 ma specific geological events within the southern australian margin can be correlated with events preserved along the medicine bow yavapai mazatzal belt in southwestern laurentia these belts were characterised by southward continental growth with varying degrees of crustal reworking and accretion of juvenile material in australia crustal reworking appears to have been the dominant process from 1800 to 1670 ma with more juvenile material accreted at 1620 ma in contrast the southern laurentian terranes were dominated by accretion of juvenile material from 1800 to 1620 ma although reworked continental crust was also accreted to the margin in the interior of both continents basins developed with comparable histories from 1800 to 1670 ma thereafter the evolution of the interior basins diverged with sag phase processes dominant in northern australia and a protracted depositional hiatus in laurentia the geologic evolution is consistent with palaeomagnetic data and provides further evidence for geographic links between eastern australia and western laurentia from 1800 to 1600 ma

sediment sources and east asian monsoon intensity over the last 450 ky mineralogical and geochemical investigations on south china sea sediments a coupled approach based on clay mineral assemblages and isotopic data sr and nd of sediment from ocean drilling program odp site 1145 has been used to trace the sources of sediment feeding the northern part of the south china sea and to investigate the evolution of east asian monsoon intensity over the last 450 ky clay mineral assemblages are dominated by illite and smectite with lesser abundance of chlorite and kaolinite 87 sr 86 sr and end 0 isotopic data combined with the smectite illite chlorite ratio indicate that the pearl river is the main contributor for detrital material to the northern margin of the scs with variable continental input of volcanic material derived from the erosion of the luzon arc these inputs follow the low latitude solar insolation with a 23 ky periodicity as recorded by a periodic change of the clay mineralogy for the first time this study presents a scs deep sea sediment high resolution record of climatic changes in the last 450 ky showing that smectite illite chlorite variations are mainly related to changes in the east asian summer monsoon intensity because the mineralogical record is independent of other external forcing phenomena such as global glacial interglacial oscillations the smectite illite chlorite ratio has been used here as a proxy to reconstruct past changes of the south east asian summer monsoon intensity d 2005 elsevier b v all rights reserved

deep weathering of granitic rocks a case of tunnelling in nw spain abstract this paper highlights a case of extensive development of saprolith from granitic bedrock in nw spain the weathering front at the study area extends to more than 250 m in depth the drilling of a railway tunnel madrid galicia high speed line through the bedrock and saprolith resulted in significant technical issues and economic losses cross sections revealing the 3d complexity of saprolith development are mainly based on fieldwork boreholes laboratory tests and the excavation works saprock is always observed overlying unweathered igneous bedrock two saprolite facies one clay rich and the other clay poor overlie the saprock the recognition is based on several criteria these deposits gradually thicken from the boundaries between the granitoid and metasedimentary roof pendants factors controlling saprolith development are discussed and the chemical and mineralogical changes and trends that occur are described variations in some geotechnical properties and the loss of quality of the rock masses from an engineering perspective are also quantified

rainfall morphology in florida convergence zones a numerical study abstract central florida is the ideal test laboratory for studying convergence zone induced convection the region regularly experiences sea breeze fronts and rainfall induced outflow boundaries the focus of this study is convection associated with the commonly occurring convergence zone established by the interaction of the sea breeze front and an outflow boundary previous studies have investigated mechanisms primarily affecting storm initiation by such convergence zones few have focused on rainfall morphology yet these storms contribute a significant amount of precipitation to the annual rainfall budget low level convergence and midtropospheric moisture have been shown to be correlated with rainfall amounts in florida using 2d and 3d numerical simulations the roles of low level convergence and midtropospheric moisture in rainfall evolution are examined the results indicate that area and time averaged vertical moisture flux vmf at the sea breeze front outflow convergence zone is directly and

heterogeneous exhumation of the mount isa orogen in ne australia after 1 6 ga nuna assembly new high precision 40ar 39ar thermochronological constraints

high resolution simulations of convective cold pools over the northwestern sahara 1 cooling by evaporation of convective precipitation in the deep and dry subcloud layer over desert regions can generate intense downdrafts and long lived and extensive atmospheric density currents the strong gusts at their leading edges can cause so called haboob dust storms despite their importance for the dust cycle the ability of state of the art numerical weather prediction models to realistically simulate the associated convective cold pools has been investigated very little to date during the first field campaign of the saharan mineral dust experiment in southern morocco in may june 2006 several density currents were observed they were triggered by deep moist convection over the atlas mountains during the afternoon and propagated into the foothills in the course of the evening here we present numerical simulations of three of these density currents using the nonhydrostatic consortium for small scale modelling model with 2 8 km horizontal grid spacing which allows an explicit treatment of deep convection the model is capable of simulating the timely initiation of convective cells over the atlas mountains and the subsequent formation of long lived extensive cold pools with a realistic three dimensional structure deviations from available surface and satellite observations are closely related to model deficiencies in simulating precipitating convection over the algerian sahara sensitivity studies with modified microphysics reveal a large influence of raindrop size distributions on evaporation and surface rainfall but a rather moderate influence on the cold pool evolution decreasing the length scale for turbulent vertical mixing in the boundary layer leads to more widespread but weaker precipitation more evaporation and a faster and more extended cold pool

suction stress characteristics in granite red soils and their relationship with the collapsing gully in south china abstract the main goal of this research is to study the relationship between the soil suction stress and soil properties within four different soil profiles of collapsing gullies in the hilly granitic region of southern china large differences were found in the four soil layers between granite red soils which are manifested in terms of soil bulk density porosity particle composition clay minerals micromorphology organic matter cation exchange capacity permeability oxide and hydraulics properties the suction stress of the upper soils increases rapidly and almost linearly monotonously with the increase of matric suction whereas c layers increases rapidly first followed by a slow increase the suction stress of the lower soils is significantly smaller than the upper soils under the same matric suction these findings illustrate that the collapsing gully starts from the lower part of the granite red soil and finally caused the gravity collapse in the upper soils which is the main aspect that is different from the other types of soil erosion furthermore suction stress has a very significant correlation with soil properties with a positive correlation to the fine particle content iron and aluminum oxide and a negative correlation to coarse particles in addition suction stress can also be explained as being directly proportional to weathering degree our research provides a theoretical basis for the mass failures of the granite derived red soil in southern china

convection initiation associated with a sea breeze front a gust front and their collision abstract the initiation of convection associated with a sea breeze front a gust front and their collision is analyzed using data collected in east central florida during the convection and precipitation electrification project in conjunction with satellite surface and rawinsonde information dual doppler radar derived winds are used to determine the three dimensional kinematic factors critical to storm development the gust front which emanated from storms on the western half of the peninsula propagated more rapidly and was deeper than the sea breeze front which originated from the east coast and was characterized by a distinctly scalloped appearance convection associated with the sea breeze front appeared to develop preferentially at the vertices of this scalloped pattern where there were enhanced regions of convergence and upward motion on the gust front a helmholtz shearing instability produced an organized configuration of convergence and updraft maxima along its length however these were

statistical empirical index of chemical weathering in igneous rocks a new tool for evaluating the degree of weathering abstract chemical weathering indices are useful tools in characterizing weathering profiles and determining the extent of weathering however the predictive performance of the conventional indices is critically dependent on the composition of the unweathered parent rock to overcome this limitation the present paper introduces an alternative statistical empirical index of chemical weathering that is extracted by the principal component analysis pca of a large dataset derived from unweathered igneous rocks and their weathering profiles the pca analysis yields two principal components pc1 and pc2 which capture 39 23 and 35 17 of total variability respectively the extent of weathering is reflected by variation along pc1 primarily due to the loss of na 2 o and cao during weathering in contrast pc2 is the direction along which the projections of unweathered felsic intermediate and mafic igneous rocks appear to be best discriminated therefore pc1 and pc2 represent independent latent variables that correspond to the extent of weathering and the chemistry of the unweathered parent rock subsequently pc1 and pc2 were then mapped onto a ternary diagram mfw diagram the m and f vertices characterize mafic and felsic rock source respectively while the w vertex identifies the degree of weathering of these sources independent of the chemistry of the unweathered parent rock the w index has a number of significant properties that are not found in conventional weathering indices first the w index is sensitive to chemical changes that occur during weathering because it is based on eight major oxides whereas most conventional indices are defined by between two and four oxides second the w index provides robust results even for highly weathered sesquioxide rich samples third the w index is applicable to a wide range of felsic intermediate and mafic igneous rock types finally the mfw diagram is expected to facilitate provenance analysis of sedimentary rocks by identifying their weathering trends and thereby enabling a backward estimate of the composition of the unweathered source rock

a two dimensional numerical investigation of the interaction between sea breezes and deep convection over the florida peninsula abstract deep convection initiated by sea breezes over the florida peninsula is simulated using a two dimensional nonhydrostatic model reasonable agreement is obtained between model results and observations for the three types of undisturbed days classified by blanchard and lopez the convergence of the east and west coast sea breezes is the primary control on the timing and location of rapid convective development and this is mainly determined by the low level winds the simulated convection is spatially concentrated and does not produce an extensive stratiform region sensitivity tests are performed for a variety of wind and thermodynamic profiles and for different soil moisture contents during the early stages of these simulations small convective cells develop in between the sea breeze fronts as the outer cells at the sea breeze fronts deepen these smaller cells are suppressed typically during the midafternoon a new cell explosively develops in between the sea breeze fronts and the outer cells

what is the mechanism for the modification of convective cloud distributions by land surface induced flows abstract the aim of this study is to determine the mechanism that modulates the initiation of convection within convergence zones caused by land surface induced mesoscale flows an idealized modeling approach linked quantitatively to observations of vegetation breezes over tropical benin was used a large eddy model was used with a prescribed land surface describing heterogeneities between crop and forest over which vegetation breezes have been observed the total surface fluxes were constant but the bowen ratio varied with vegetation type the heterogeneous land surface created temperature differences consistent with observations which in turn forced mesoscale winds and convection at the convergence zones over the crop boundaries at these convergence zones optimum conditions for the initiation of convection were found in the afternoon the equivalent potential temperature was higher in the convergence zones than over anywhere else in the domain due to reduced entrainment and the mesoscale convergence

characteristics of weathering zones of granitic rocks in malaysia for geotechnical engineering design tropical climatic conditions cause severe weathering to rock masses resulting in thick weathering profiles consisting of different weathering zones with complex characteristics feasible geotechnical engineering design requires a detailed understanding of the characteristics of each weathering zone a typical weathering profile is usually characterized by field scale observation and geological study this paper presents the characteristics of weathering zones of various granitic rocks in the south of malaysia this region has a tropical climatic condition the study was carried out in four active quarries located in johor province malaysia and forty sections were investigated in the study areas a typical granitic weathering profile was characterized based on the geological and structural parameters i e joint characteristics corestone occurrence rock soil ratio mass homogeneity color of rock and discoloration at joints surfaces the profile includes common zones ranging from fresh to residual soil however two subzones are introduced based on corestone boulder occurrence in the highly weathered and completely weathered zones this study based on detailed field observations at the mentioned quarries followed by analysis presents an amalgamated picture of weathering zones in granitic profiles of a tropical region like malaysia moreover it is believed that the characterization of the typical weathering profile allows further classification of generally complex weathered rock masses for a specific geotechnical engineering design

zircon provenances provide paleogeographic constraints on models reconstructing the paleoproterozoic columbia supercontinent abstract paleoproterozoic orogens of the north australian craton are related to the assembly of the columbia supercontinent the roles of the distinct orogens in the paleoproterozoic craton amalgamation are poorly understood due to the lack of surface exposure the age and isotopic systematics of detrital zircon grains hosted in paleoproterozoic sedimentary sequences are used to unravel the geological history of the craton in terms of paleogeography and tectonic setting the oldest early paleoproterozoic metasedimentary units are characterised by detrital zircon ages peaking at ca 2500 ma the zircon ehf values show large variations in the different orogens and range from 18 to 6 the overlaying youngest turbiditic units show minor accumulation of archean detritus units from apparently different metasedimentary sequences have a major detrital zircon age population at ca 1865 ma and a relatively restricted range of zircon ehf values between 7 3 and 2 6 the isotopic distinctiveness of the oldest units is attributed to local variations in the depositional environment probably due to horst graben architecture of the early paleoproterozoic basin the youngest turbiditic units blanketed this early horst graben architecture and in part have a local provenance potential detritus sources include south australian craton dharwar craton and aravalli lesser himalayan terrains in india south china and madagascar africa this finding indicates that these regions might have been connected before the columbia supercontinent was formed the ubiquitous ca 2500 ma magmatic event records the assembly of these cratonic fragments in a previous supercontinent called kernorland in addition the data do not support a proximity of the north australian craton with the north china block western laurentia north america and kaapvaal craton africa during columbia amalgamation