exfoliation microcracks in building granite implications for anisotropy abstract granite is found in many world heritage monuments and cities it continues to be one of the most widely used stones in today s construction given its abundance uniformity and durability quarrymen traditionally cut this rock along its orthogonal slip planes where splitting is easier ranked by ease of splitting these planes are rift grain and hardway granite is traditionally quarried along the rift plane where coplanar exfoliation microcracks coalesce developing a flat surface this splitting surface minimizes the cost and effort of subsequent hewing rift plane was predominantly used on the fair face of ashlars in heritage buildings worldwide determining the petrographic and petrophysical behaviour of these three orthogonal splitting planes in granite is instrumental to understanding decay in ashlars and sculptures the decay of building granite is different in each splitting plane alpedrete granite was the stone selected for this study based on the orientation and distribution of exfoliation microcracks and the characterisation of their implications for the anisotropy of petrophysical properties such as ultrasonic wave propagation capillarity air permeability micro roughness and surface hardness inter and intracrystalline microcrack length and spacing were also measured and quantified the findings show that the splitting planes in alpedrete granite are determined by the orientation of exfoliation microcracks which as a rule are generally straight and intracrystalline and determine the anisotropy of the petrophysical properties analysed splitting planes are the orientation that should be applied when performing laboratory tests for the petrographic and petrophysical properties of building granite

the effect of rock strength on weathering rates of sandstone used for angkor temples in cambodia abstract this study determined the weathering rates from the depths of hollows formed by the deterioration of sandstone blocks used to build angkor temples in the 7th 12th centuries due to capillary processes these hollows generally develop at the bases of building components such as doorframes false doorframes window frames and pillars in this study 55 locations in 29 temples were selected to measure maximum hollow depth based on the ages of the temples the weathering rate was calculated to be in the range 7 92 mm ka 1 the weathering rate was found to be independent of building component type and aspect the calculated weathering rate corresponds to the physical weathering rate of sandstone caused by the wetting drying cycles that result from the tropical environment along with the dry season an equation that can estimate the maximum depth of a hollow in a sandstone block was proposed based on temple age and the coefficient obtained from two types of rock hardness values the equation coefficient is an effective index that can help predict the deterioration of stone cultural artifacts such as the angkor temples

the physical properties of quartz micaschist and their application to freeze thaw weathering studies in the maritime antarctic as part of a study on freeze thaw weathering in the maritime antarctic an investigation was made of the physical properties of the local rock tests were made of point load compressive strength schmidt hammer in situ rock strength moisture content indentor resistance and the size range of weathering products the resulting data were used to consider the form of freeze thaw weathering operative in the field and its relationship to laboratory simulations a distinct difference between massive rock and intact rock is observed in the field it is suggested that future studies should generate a greater database pertaining to rock properties as it is an invaluable aid in the study of mechanical weathering

late cenozoic tectonic evolution of the southern chinese tian shan structural sedimentological magnetostratigraphic and 40ar 39ar thermochronological investigations were conducted in the southern chinese tian shan on the basis of our own mapping and earlier investigations in the area the late cenozoic southern tian shan thrust belt may be divided into four segments based on their style of deformation from west to east they are 1 kashi aksu imbricate thrust system 2 the baicheng kuche fold and thrust system 3 the korla right slip transfer system and 4 the lop nor thrust system the westernmost kashi aksu system is characterized by the occurrence of evenly spaced 12 15 km imbricate thrusts the baicheng kuche and korla systems are expressed by a major north dipping thrust the kuche thrust that changes its strike eastward to become a nw striking oblique thrust ramp the korla transfer zone the lop nor system in the eastern most part of the southern chinese tian shan consists of widely spaced thrusts all involved with basement rocks geologic mapping and cross section construction suggest that at least 20 40 km of crustal shortening with a horizontal shortening strain of 20 30 has occurred in the southern chinese tian shan during the late cenozoic these estimates are minimum because of both conservative extrapolation of the thrust geometries and partial coverage of the thrust belt by the cross sections the timing of initial thrusting is best constrained in the kuche basin where crustal shortening may have occurred at 21 24 ma the time of a major facies transition between lacustrine and braided fluvial sequences constrained in general by biostratigraphy and in detail by magnetostratigraphy this estimate represents only a minimum age as development of thrusts in the southern chinese tian shan may have propagated southward toward the foreland thus the sedimentary record only represents the southernmost and therefore youngest phase of thrusting if our estimate of timing for the thrust initiation 21 24 ma is correct using the estimated magnitude of shortening 20 40 km and shortening strain 20 30 the averaged rates of late cenozoic horizontal slip and shortening strain are 1 1 9 mm yr 1 and 2 9 4 5 10 16 s 1 respectively our reconnaissance 40ar 39ar thermochronological analysis in conjunction with earlier published results of apatite fission track analysis by other workers in the chinese tian shan suggests that the magnitude of cenozoic denudation is no more than 10 km most likely less than 5 km we demonstrate via a simple airy isostasy model that when the thermal effect on changes in surface elevation is negligible determination of the spatial distribution and temporal variation of both horizontal shortening strain and denudation becomes a key to reconstructing the elevation history of the tian shan using this simple model the loosely constrained magnitude of crustal shortening strain and denudation in the southern chinese tian shan implies that it may have been elevated 1 0 2 0 km since the onset of cenozoic thrusting

lightning as a geomorphic agent on mountain summits evidence from southern africa abstract the presence of angular bedrock derived debris on mountain summits worldwide has usually been associated with present or past periglacial frost shattering thermal fracturing and other climatically mediated weathering processes climatic inferences are commonly made based on such geomorphological evidence even if frost shattering and other processes are unlikely under present climatic conditions this paper questions this assumed genetic link between present past climate and production of angular bedrock derived debris by describing the geomorphological impacts of lightning strikes on exposed mountain summits using examples from the high drakensberg of eastern lesotho southern africa the impacts of lightning strikes are described which include the generation of angular fractured bedrock derived debris these impacts are identified in the field based on clear and unambiguous criteria that can be used to distinguish between lightning induced weathering processes and those processes associated with more typical alpine weathering this paper argues that lightning strikes are an important geomorphic agent of in particular low latitude mountain summits and that to make uncritical climatic inferences based on the presence of frost shattered debris on mountain summits is wholly erroneous

variability of the rebound hardness as a proxy for detecting the levels of continuity and isotropy in archaeological quartz abstract the equotip hardness tester is applied to different types of quartz and other lithic raw materials in order to determine if variations in the rebound hardness measured by this device may serve as a proxy for detecting the levels of continuity and isotropy of toolstones continuity the amount of cracks and other internal defects and isotropy the measure of the directional properties of a raw material are known to have important effects on the level of consistency and predictability of fractures which in turn is traditionally considered a main factor for defining the flaking quality of a given raw material the results demonstrate the existence of differences among the raw materials analysed in both the average value and the variability of the rebound hardness while cryptocrystalline samples show the most homogeneous results quartz and metamorphic rocks display a comparatively higher variance in the specific case of quartz such variability seems to be mainly caused by the presence of internal planes and discontinuities while anisotropy although also active had played a comparatively modest role the results achieved by the equotip hardness tester suggest that this device could be successfully used for a basic or preliminary estimating of some of the physical and mechanical properties of stone raw materials therefore it is a potential index test for complementing other more accurate laboratory methods

development of shore platforms on kaikoura peninsula south island new zealand ii the role of subaerial weathering the role of subaerial weathering in the development of shore platforms on kaikoura peninsula is investigated evidence for weathering came from a number of distinctive surface morphologies on platforms salt crystal growth water layer weathering and slaking schmidt hammer test data showed that weathering had occurred and that rock strength was reduced through weathering by as much as 50 weathering processes on shore platforms rely on repeated wetting and drying and for this reason the number of wetting and drying cycles was estimated it was found that the number of wetting and drying cycles depend not only on the pattern of tidal water levels but also on algae growth and desiccation the number of cycles ranged from 104 to 379 per year at elevations low in the tide range fewer cycles occurred the greatest number occurring between the peaks of spring and neap tides and where rainfall adds to the number the zone of most cycles was estimated to occur between 0 6 and 0 9 m above mean sea level on the more landward margins of platforms it is at these elevations that the highest rates of erosion occur based on these results it is argued that the development of shore platforms at kaikoura results from subaerial weathering caused by repeated wetting and drying this is contrary to the view that shore platforms result from marine erosion

reconceptualising the role of organisms in the erosion of rock coasts a new model attempts to understand the morphodynamics of rock coasts focus on the nature and rate of erosion and how this influences the evolution of coastal profiles over century to millennial timescales biological contributions to this process are often ignored or treated in a rather simplistic way as merely producing microscale decreases in rock strength using a combination of field observations and literature review we address two key issues hampering a more rounded assessment of biological impacts erosion of coastal rocks firstly we reconceptualise the biological contributions to erosion of rock coasts into direct and facilitative types and secondly we discuss the need for more appropriate reporting of rates of bioerosion for direct bioerosion this means clearly documenting the percentage of platform surfaces affected by bioerosive agents and quantifying the volume of material eroded and the amount of fine sediment produced for facilitative bioerosion we must quantify the roles of biota in changing the material properties of rocks creating or altering surface morphologies and or weakening joint boundaries in this way facilitative bioerosion is one of several processes mediating geomorphic alteration of rock surfaces contributing to the production of landforms and or reducing the resisting force of rock subsequently we build on these ideas to produce a new conceptual model which more accurately portrays the multiple and cross scalar ways that biological processes notably bioerosion influence the resistance of coastal rocks to erosive forces such a model provides a stronger basis for numerical modelling and understanding the morphodynamics of rock coasts in the future and allows a quantitative assessment of the role of biota

role of the kazerun fault zone in the formation and deformation of the zagros fold thrust belt iran 1 the kazerun fault is a n s trending fault zone which obliquely truncates the nw se trending zagros fold thrust belt this active fault zone is an ancient structural lineament which has controlled the structure sedimentation and subsidence of the central part of the zagros since the early cambrian and has had an influence on the formation of the hydrocarbon system of the belt the kazerun fault limited the distribution of the cambrian hormuz salt the major decollement horizon that separates the precambrian basement from the thick sedimentary cover to the west its later reactivation with other n s trending fault zones e g the izeh fault zone during the cretaceous resulted in major sedimentary thickness and facies variations along the belt this study presents a new interpretation for the evolution of the kazerun fault zone based on field evidence and a review of various published and unpublished data it is argued that at the surface the fault zone is delineated by four north south trending segments and that marked differences occur in the distribution of deformation on either side of the fault segments in the late tertiary during this time these segments acted as transfer faults lateral ramps linking different segments of the zagros deformation fronts

structural framework of the zagros fold thrust belt iran abstract data gleaned from the literature on the zagros have been compiled and used in conjunction with new interpretations to provide a better picture of the structures sedimentation history and deformation of this hydrocarbon rich mountain belt the belt parallel mountain front the n s trending kazerun izeh and e w trending bala rud fault zones are defined as the master structural elements of the belt these fault zones divide the zagros basin into zones with different stratigraphic successions and different rheological profiles this resulted in different structural styles developing along the belt during the subsequent collision the kazerun and izeh fault zones acted as the depositional system transition zone between the lurestan and fars regions in jurassic cretaceous time and partly controlled the distribution of the kazhdumi formation one of the major source rocks by the end of the cretaceous the nw se trending mountain front fault divided the present folded belt of the zagros into a major foreland basin to the southwest and a piggyback basin to the northeast activity along other major transfer fault zones including the izeh kazerun and bala rud fault zones occurred at this time and controlled the sedimentation and subsidence of the dezful embayment the main target region for hydrocarbon exploration these fault zones controlled the thickness of the asmari formation one of the main reservoirs and also the considerable thickness and facies changes of the gachsaran formation the major seal to the asmari formation the present morphology of the mountain belt is interpreted as being mainly related to the pinning of the mountain front fault to the northwest of the dezful embayment and to the north of the strait of hormuz

a non destructive tool for detecting changes in the hardness of engineering materials application of the equotip durometer in the coastal zone non destructive tools capable of measuring the condition and geomechanical properties of construction materials through time are of considerable value in engineering here the ability of the equotip durometer proceq type d to detect changes in the hardness of concrete and rock exposed to marine conditions was tested results indicated a progressive loss of hardness for limestone while concrete hardness increased granite showed no significant change our results relate to alteration of the materials primarily via chemical and biological weathering the equotip is sensitive enough to detect subtle changes in the condition of construction materials over relatively short periods of time

the role of rock surface hardness and internal moisture in tafoni development in sandstone the development of cavernous weathering features such as tafoni remains poorly understood in particular the roles played by internal moisture and case hardening remain unclear in this study electric resistivity tomography ert has been used to map moisture distribution within inner walls of tafoni developed in sandstone and an equotip device used to measure rock surface hardness as a proxy measure of the degree of weathering and case hardening seven large tafoni in the golden gate highlands national park south africa varying in size and degree of development have been monitored a dynamic relationship between surface hardness degree of weathering and internal moisture regimes has been found we propose a new conceptual model which illustrates the complex interaction between case hardening and internal moisture and suggests a new direction for cavernous weathering research copyright 2011 john wiley sons ltd

seaweeds through time morphological and ecological analysis of proterozoic and early paleozoic benthic macroalgae abstract benthic marine macroalgae or seaweeds are key ecological players in oceans today and have been since the proterozoic to date however morphological and evolutionary patterns for precambrian macroalgae have been documented only in rather broad terms to refine our understanding in this critical interval we updated a dataset of proterozoic to early paleozoic noncalcified macroalgal fossils preserved as macroscopic carbonaceous compressions the data were analyzed using non parametric multidimensional scaling nmds and functional form group ffg approaches in order to characterize morphological and ecological evolutionary patterns of these macroalgae at the broadest scale the results show progressive increases in thallus size morphospace range and aspects of ecological complexity such as canopy heights surface area volume ratios and functional form groups through time these trends however are not always monotonous in particular significant increases in proterozoic macroalgal morphological diversity and maximum size appear to have occurred in the neoproterozoic tonian and ediacaran periods respectively analysis of ediacaran macroalgal assemblages shows that macroalgae broadly follow the ediacara like fossil assemblages with a significant drop in most studied metrics in the terminal ediacaran stage 550 539 ma the latter event occurs during the kotlinian crisis experienced by ediacara type macro organisms highlighting the possibility that this extinction event during the ediacaran cambrian transition affected both macroalgae and ediacara type macro organisms our analysis also confirms an ordovician increase in the morphological and ecological diversity of macroalgae

kotuikan formation assemblage a diverse organic walled microbiota in the mesoproterozoic anabar succession northern siberia abstract abundant and diverse microfossils from shales of the lower member of the 1500 ma old kotuikan formation in northern siberia document early mesoproterozoic life along the siberian platform similar to many meso and neoproterozoic microbiota the kotuikan assemblage is dominated by prokaryotic cyanobacteria both filamentous oscillatorialeans and nostocaleans which are represented primarily by cellular trichomes and by empty sheaths and coccoidal chroococcaleans including solitary and colonial specimens however unlike mesoproterozoic microbiota of shallow water settings the kotuikan compressed organic walled microfossil assemblage in the open shelf facies includes diverse microscopic eukaryotes large up to 1 mm diameter megasphaeromorph acritarchs branched filaments that are most likely of eukaryotic algae and coccoidal monostromatic colonies of chlorococcaleans as well as other morphologically complex microorganisms the kotuikan assemblage contains numerous taxa previously recorded from neoproterozoic successions e g elatera eosolena palaeastrum pterospermopsimorpha rugosoopsis and navifusa but these are long ranging genera and no neoproterozoic index fossils have been recorded the microbiota is considered to be mesoproterozoic in age because it contains a mixed assemblage of prokaryotic and eukaryotic microorganism remains including new taxa unknown in younger deposits the kotuikan assemblage documents the status of the marine biosphere at an early mesoproterozoic time preceding the primary radiation of eukaryotes and representing an evolutionary stage transitional between the predominantly prokaryote dominated paleoproterozoic and the eukaryote dominated neoproterozoic microbiota as reported in this study 35 taxa were identified in the kotuikan assemblage of which five forms are described informally that are assigned to 18 genera of microscopic prokaryotes and eukaryotes two new genera and five new species are proposed hirudiforma lancetica gen and sp nov h simmetrica gen and sp nov lineaforma elongata gen and sp nov elatera minor sp nov eosolena minuta sp nov

methods for measuring rock surface weathering and erosion a critical review studies of rates processes and modes of rock surface and near surface deterioration and also hardening are central to rock weathering and building stone research conservation and management there is a need to measure and monitor weathering at the rock atmosphere interface to facilitate understanding of climatic environmental and lithological controls on the evolution and development of surface weathering features this paper reviews long established and recently developed field and laboratory methods used by geomorphologists to monitor and measure the impact of weathering and erosion on physical and mechanical properties of exposed rock surfaces and their immediate subsurface key advances are highlighted their application to multi scalar understanding and modelling of rock surface weathering in different contexts is discussed and potential future advances to provide new insights into rock weathering durability and materials conservation are identified in highlighting key advantages and disadvantages of a wide range of methods to the broader earth science community the paper aims to contribute to further innovative thinking across disciplines to develop new methods for measuring and monitoring rock weathering

late paleozoic tectonic amalgamation of northwestern china sedimentary record of the northern tarim northwestern turpan and southern junggar basins sedimentary rocks contained in basins adjacent to the tian shan provide a long and complex record of the late paleozoic continental amalgamation of northwestern china complementing that provided by rocks preserved within the range this record which comprises dramatic changes in sedimentary facies sediment dispersal patterns sandstone provenance and basin subsidence rates broadly supports previous interpretations of a two part evolution of the tian shan late devonian to early carboniferous collision of the tarim continental block with the central tian shan followed by collision of this combined block with island arcs in the north tian shan and bogda shan in late carboniferous early permian times the first collision resulted in widespread angular unconformities within the tarim basin continued convergence following the collision created a long lived flexural foredeep along the northern margin of the tarim block which received at least 2000 m of lower carboniferous through lower permian fluvial and marine sediment derived from the interior of tarim subsequent early permian continental extension of the northern tarim basin resulted in the deposition of interbedded nonmarine siliciclastic sedimentary rocks and mafic to felsicvolcanic rocks sandstone within this interval was derived from the paleo tian shan and is composed predominantly of lithic volcanic grains similar to the rhyolite in contrast to the tarim basin calc alkaline volcanic rocks and volcanogenic sedimentary rocks dominated carboniferous and permian sedimentation in the northern turpan and northwestern junggar basins volcanic arcs remained active in the north tian shan and bogda shan through the early late carboniferous depositing a kilometers thick interval of deep marine sediment gravity flows in the northwestern junggar basin major arc magmatism ceased in the late carboniferous in response to closure of the oceanic basin between the combined tarim central tian shan block and the north tian shan bogda shan arcs upper carboniferous through lower permian rocks in the northwestern junggar basin compose the sedimentary fill of a bathymetric basin of oceanic depth on the northern side of the volcanic arcs culminating in a 1000 m thick marine regressive sequence middle to upper permian sandstones were derived from the uplifted paleo tian shan and bear the distinctive provenance imprint of granitic rocks presently exposed within the range late permian subsidence of the junggar basin accommodated 5 km of nonmarine sediments however the cause of this subsidence and its relationship to regional tectonic events remain controversial

measurement and calibration of weathering using the schmidt hammer on wave washed moraines on the upper norrland coast sweden the schmidt hammer has for some years been used to measure the hardness of different rock surfaces and to date relatively boulders in moraine deposits in this paper applications on isostatically raised boulder beaches and rocky shores are described the research area is the northern swedish bothnian coast where present isostatic uplift is between 0 8 1 0 cm year 1 elevations above sea level can be converted to a timescale rebound values r of the schmidt hammer are correlated with the altitude and the degree of rock weathering can be estimated for each site eight sites with boulder beaches and nine sites with rocky shores have been analysed for boulder beaches correlation coefficients of 0 82 0 97 for weathering values r and the elevations above sea level were obtained for the rocky shores these values were calculated to 0 75 0 97 this method has applications in both geomorphology and archaeology for example a deep layer of weathered dolerite in the nordingra region which previously has been regarded as a post weichselian formation can be shown to be of pre weichselian origin several archaeological applications are also mentioned in the paper

low impact surface hardness testing equotip on porous surfaces advances in methodology with implications for rock weathering and stone deterioration research 2015 john wiley and sons ltd the equotip surface hardness tester is becoming a popular method for rock and stone weathering research in order to improve the reliability of equotip for on site application this study tested four porous limestones under laboratory conditions the range of stone porosity was chosen to represent likely porosities found in weathered limestones in the field we consider several key issues i its suitability for soft and porous stones ii the type of probe required for specific on site applications iii appropriate non parametrical statistical methods for equotip data iv sufficient sampling size this study shows that the equotip is suitable for soft and porous rock and stone from the two tested probes the dl probe has some advantages over the d probe as it correlates slightly better with open porosity and allows for more controlled sampling in recessed areas and rough or curved areas we show that appropriate sampling sizes and robust non parametric methods for subsequent data evaluation can produce meaningful measures of rock surface hardness derived from the equotip the novel hybrid dynamic hardness a combination of two measuring procedures single impact method sim and repeated impact method rim has been adapted and is based on median values to provide a more robust data evaluation for the tested stones in this study we propose a sample size of 45 readings for a confidence level of 95 this approach can certainly be transferred to stone and rock with similar porosities and hardness our approach also allows for consistent comparisons to be made across a wide variety of studies in the fields of rock weathering and stone deterioration research

organic walled microfossils from the tonian tongjiazhuang formation of the tumen group in western shandong north china craton and their biostratigraphic significance abstract neoproterozoic successions in western shandong of north china craton contain fine grained siliciclastic rocks which offer a unique opportunity to explore the neoproterozoic biosphere in this study we have revealed a well preserved and diversified microfossil assemblage from the tongjiazhuang formation tumen group in western shandong north china craton which is characterized by abundant smooth walled sphaeromorphic acritarchs and cyanobacterium like filamentous forms and relatively low abundance of more complex acritarchs a total of 40 microfossil taxa belonging to 20 morphological genera have been identified most of which are described for the first time from the tongjiazhuang formation of the tumen group in western shandong including simia sp trachyhystrichosphaera aimika t botula germinosphaera bispinosa unnamed sp a jacutianema solubila and pololeptus rugosus the tongjiazhuang assemblage revealed in this study is much more diverse than previously reported and well comparable to the tonian liulaobei and gouhou assemblages in the xuhuai region particularly the occurrence of t aimika t botula g bispinosa j solubila and p rugosus indicates a late mesoproterozoic to tonian age for the tongjiazhuang formation in addition the occurrences of macroscopic carbonaceous compressions including chuaria tawuia assemblage from the tongjiazhuang formation and tawuia and sinosabellidites from the shiwangzhuang formation are consistent with geochronological data suggesting a tonian age for the tongjiazhuang fulaishan and shiwangzhuang formations of the middle and upper tumen group while the heishanguan and erqingshan formations of the lower tumen group are likely late mesoproterozoic to tonian in age thus available biostratigraphic data lithostratigraphic correlation and geochronological data suggest that the whole tumen group is late mesoproterozoic to tonian in age rather than cryogenian or ediacaran this study significantly improves our knowledge about the diversity of the tonian biosphere and implies a 200 300 million years unconformity the great unconformity between the late mesoprotoerozoic to tonian tumen group and the early cambrian liguan formation in western shandong

tafoni on coastal slopes south devon u k cavernous weathering tafoni development occurs on coastal slopes in greenschist bedrock at elevations up to 40 m above sea level the freshly weathered surfaces of the cavern interiors are irregular in morphology discordant to major rock structure formed by substantially weakened rock and associated with granular weathering debris the weathering debris contains soluble elements in proportions similar to those present in seawater and the penetration of elements associated with sea salts into the weathering surface to estimated depths of at least 0 1 0 2 m is indicated by the presence of chlorine scanning electron microscopy and microprobe analyses suggest that rock breakdown occurs principally through limited chemical weathering at grain boundaries the mechanism for the emplacement of marine salts within sheltered rock surfaces in the tafoni is postulated to be a combination of dry deposition under turbulent atmospheric conditions and wetting by coastal fog

a global transition to ferruginous conditions in the early neoproterozoic oceans eukaryotic life expanded during the proterozoic eon1 2 5 to 0 542 billion years ago against a background of fluctuating ocean chemistry2 3 4 after about 1 8 billion years ago the global ocean is thought to have been characterized by oxygenated surface waters with anoxic and sulphidic waters in middle depths along productive continental margins and anoxic and iron containing ferruginous deeper waters5 6 7 the spatial extent of sulphidic waters probably varied through time5 6 but this surface to deep redox structure is suggested to have persisted until the first neoproterozoic glaciation about 717 million years ago8 9 10 11 here we report an analysis of ocean redox conditions throughout the proterozoic using new and existing iron speciation and sulphur isotope data from multiple cores and outcrops we find a global transition from sulphidic to ferruginous mid depth waters in the earliest neoproterozoic coincident with the amalgamation of the supercontinent rodinia at low latitudes we suggest that ferruginous conditions were initiated by an increase in the oceanic influx of highly reactive iron relative to sulphate driven by a change in weathering regime and the uptake of sulphate by extensive continental evaporites on rodinia we propose that this transition essentially detoxified ocean margin settings allowing for expanded opportunities for eukaryote diversification following a prolonged evolutionary stasis before one billion years ago

weathering distribution in a steep slope of soft pyroclastic rocks as an indicator of slope instability abstract weathering of rocks on steep slopes influences slope instability and sometimes leads to slope failure during heavy rainfall to determine the weathering intensity of hillslope rocks and its inward change from the slope surface measurements of the penetrative hardness of rocks which correlates with their strength were made in some slopes composed of soft pyroclastic rocks on kyushu island japan a gradual reduction in hardness from the interior to the slope surface was recognized within slopes the hardness change was almost concordant with changes in other weathering indices such as rock color clay minerals and apparent grain size the weathered zone indicated by the reduction in hardness was 1 2 m thick at the foot of steep slopes which are frequently subjected to gullying and surface failures whereas the zone was 7 8 m thick at slope summits which are gentle and stable for a long period although the inward change in hardness was gradual on all parts of a slope the change was marked on the foot slope where the strength contrast between weathered and non weathered rock was greater the thickness of the weathered zone on the foot slope therefore controls the volume of failed materials when a failure occurs the difference in weathered thickness between the foot and the summit of a slope much affects the style of failure in general and consequently shapes the characteristic configuration of slopes in this region the estimated weathering rate on a slope surface based on hardness distribution was on the order of 10 2 to 100 cm year 1 assuming a constant rate this rate is far greater than that of other rocks therefore the frequent occurrence of slope failures in this region was attributed to this rapid weathering

basin analysis of the jurassic lower cretaceous southwest tarim basin northwest china the jurassic through cretaceous southwest tarim basin northwest china contains more than 6 km of fluvial and lacustrine strata deposited in a foreland setting during the successive collisions with eurasia of the changtang block during late triassic early jurassic time and with the mega lhasa block during late jurassic early cretaceous time this tectonism is chronologically linked with the creation of a narrow lower middle jurassic transtensional basin with thick sedimentary infill succeeded by a broader upper jurassic lower cretaceous compressional basin with thinner sedimentary infill the older basin formed between a north northwest striking dextral fault on the eastern side of the southwest tarim basin in the tian shan and a postulated strike slip or normal fault on the western margin of the basin along the kunlun shan the former fault is now the talas ferghana fault the latter may be a predecessor to the main pamir thrust subsidence analysis of the thickest sedimentary section suggests thermal subsidence interpreted as the result of transtension between the two basin bounding faults the younger basin extends farther east and west and does not preserve evidence of activity along the talas ferghana fault the change in basin style between these two episodes of basin development likely reflects either a small counterclockwise rotation of basin bounding structures during the first episode or a small clockwise rotation of the maximum compressive stress between the two episodes

late cenozoic tectonics of the kepingtage thrust zone interactions of the tien shan and tarim basin northwest china the kepingtage kalpin thrust zone northwest china is an actively deforming part of the india asia collision system it lies south of the tien shan has an area of 16 000 km2 and consists of arcuate emergent imbricates overall vergence is toward the interior of the tarim basin to the south thrust sheets typically expose upper cambrian to permian platformal strata thrusting is largely thin skinned thin upper cambrian evaporites are likely to be the main decollement horizon the kepingtage thrust zone is the only margin of the tarim basin to deform in this style in the cenozoic it is replaced to the east and west by thrust zones which have propagated shorter distances into the interior of the tarim basin thick up to 10 km mesozoic and cenozoic clastic successions are present and deformed in these regions such successions are not present in the kepingtage thrust zone or the adjacent bachu uplift within the tarim basin because of episodic activity on steep northwest southeast trending thrusts which define the margins of the bachu uplift these mesozoic cenozoic strata may have suppressed the ability of regions along strike from the kepingtage thrust zone to deform by thin skinned thrusting utilizing the upper cambrian decollement the along strike variation in active thrusting at the southern margin of the tien shan is an example of syntectonic sedimentation controlling thrust belt deformation style a balanced section across the thrust zone indicates 28 shortening equivalent to 35 km this is equivalent to an average slip rate of 1 8 mm yr 1 and a strain rate of 4 4 10 16 s 1 assuming deformation began at circa 20 ma active deformation is focused along the frontal thrust the kepingtage fault the northern boundary of the kepingtage thrust zone is formed by the south tien shan fault this major north dipping thrust is seismically active with published earthquake focal depths at midcrustal levels 14 and 18 km it juxtaposes upper carboniferous sedimentary rocks of different facies and different paleozoic deformation histories speculatively it represents a reactivation of a late paleozoic thrust which originated at the boundary between the platformal interior of the tarim block and a deeper water foreland basin to its north

rock resistance to erosion some further considerations rock resistance to erosion is an often described factor in geomorphic studies and is generally considered to strongly influence the shape of erosional landforms however the property of the rock mass that enables it to resist erosion is rarely considered and its measurement is rarely justified and assessed adequately allison 1988 1990 examined the intact strength properties of several types of carbonate rocks and considered that dynamic young s modulus is a good indicator of rock material strength for geomorphic purposes and cast doubts on the reliability of schmidt hammer tests for this purpose alternative approaches to rock characterization from the view point of evaluating rock intact strength are considered

taxonomy and affinity of early mesoproterozoic megascopic helically coiled and related fossils from the rohtas formation the vindhyan supergroup india abstract a well preserved assemblage of compressed straight circular to sinuously coiled megascopic and helical carbonaceous fossils and other varied megascopic morphoforms are known from the early mesoproterozoic rohtas formation semri group within vindhyan supergroup exposed in katni district of central india these megascopic remains are preserved as impressions compressions partially mineralized remains and or epi relief some of the forms are typical filamentous empty sheaths and others are trichomes with cell like entities under various stages of degradation this study based on fresh collections and also of the topotype material of the helically coiled megascopic fossils straight forms and related fossilized remains occurring as epi relief from katni indicate that the two morphotaxa are distinct entities and possibly appear to be prokaryotes grypania spiralis and katnia singhii are most likely of cyanobacterial origin spirally coiled and circular fossils with epi relief and which probably represents a tissue grade organism are considered as spiroichnus beerii mathur 1983 linear sheet like carbonaceous solitary form has been placed in the morphotaxon proterotainia and described as p katniensis n sp certain rare circular carbonaceous forms are considered as chuaria sp a few circular disc like forms found in the assemblage are treated as dubiofossils

evidence of organic structures in ediacara type fossils and associated microbial mats ediacara type fossils represent a group of soft bodied organisms mainly known from imprints in proterozoic coarse grained siliciclastic sedimentary rocks circular compressions of beltanelliformis brunsae and remains related to ediacara type fossils such as cucullus fraudulentus and mucuplagum primitivum are reported here in an organic mode of preservation from the neoproterozoic doushantuo and liulaobei formations of china they can be interpreted as prokaryotic colonies a charnid fossil with circular attachment disc and stalk but torn off frond is documented in a three dimensional and partly organic mode of preservation from the neoproterozoic ust pinega formation white sea coast russia according to their morphology and structure the charniidae are not regarded by us as pennatulaceans modern myxobacteria illustrate that macroscopic size complexity and even compartmentalization can also be developed by prokaryotic colonies part of the ediacara type fossils may therefore represent prokaryotic colonies or symbiotic organisms involving prokaryotes finally direct evidence indicates that biofilms with associated prokaryotic sheaths preserved in both organic and pyritic fashion form the wrinkled surfaces elephant skin that were preferentially colonized by ediacara type fossils this finding supports previous interpretations based on comparative morphological and sedimentological approaches that ancient wrinkle structures were microbial mats

microbiotas from the late proterozoic chuar group northern arizona and uinta mountain group utah and their chronostratigraphic implications abstract samples of shales from the dominantly clastic upper proterozoic chuar and uinta mountain groups in northern arizona and utah yielded relatively abundant assemblages of acritarchs these are taxonomically varied and are interpreted as consisting of openwater cosmopolitan eukaryotic plankton the assemblages are compared with late proterozoic late riphean and early vendian c 800 700 ma sequences in the southern urals of the ussr the russian platform northern and southern scandinavia svalbard and east and north west greenland in all instances both the assemblages and discrete form taxa predate the varangerian vendian glacial event of the north atlantic region and this is taken to indicate a comparable age for glaciogenic rock units in western north america one new acritarch species vandalosphaeridium walcottii is erected and the partly megascopic species chuaria circularis is emended

the use of the schmidt hammer and equotip for rock hardness assessment in geomorphology and heritage science a comparative analysis rapid field based measurements of rock hardness are of use in investigating many geomorphological and heritage science problems several different methods are now available for taking such measurements but little work has been done to assess their comparability and strengths and weaknesses we review here the capabilities of two types of schmidt hammer classic n type and silver schmidt bl type alongside two types of equotip standard type d and piccolo for investigating rock hardness in relation to rock weathering on various types of sandstone and limestone as well as basalt and dolerite whilst the two schmidt hammers and the two equotips show comparable results when tested at 15 individual sites interesting differences are found between the equotip and schmidt hammer values which may reveal information about the nature of weathering on different surfaces operator variance is shown to be an issue in particular for the equotip devices which also exhibit higher variability in measurements and necessitate larger sample sizes carborundum pre treatment also has varying effects on the data collected depending on the nature of the surface studied the equotip devices are shown to be particularly useful on smaller blocks and in situations where edge effects may affect schmidt hammer readings we conclude that whilst each device contributes to geomorphological research they do not necessarily produce comparable information indeed using schmidt hammer and equotip in combination and looking at any differences in results may provide invaluable insights into the structure of the near surface zones and the nature of weathering processes copyright 2010 john wiley sons ltd

rock hardness and landform development in the gunong mulu national park sarawak e malaysia rock hardness measured by the schmidt test hammer is an important factor in explaining some of the sharp contrasts in relief and wide variety of landforms in the gunong mulu national park it is also useful in consideration of contemporary geomorphological processes such as landsliding

correlating river terrace remnants using an equotip hardness tester an example from the mino river northwestern iberian peninsula abstract this paper describes a new method to distinguish river terrace levels based on clast hardness and degree of weathering measured with an equotip hardness tester the technique was applied to a series of terraces on the mino river in the northwestern iberian peninsula where the lack of suitable material high degree of weathering and intense iron cementation precluded routine dating detailed mapping demonstrated that terrace sediments occupy a range of altitudes that make assignment to a specific terrace and or correlation between levels difficult statistical analysis of the equotip hardness data from quartzite clasts using k means clustering allowed four probable terrace levels to be identified a series of t tests generally supported these groupings a fifth lowermost terrace level was not included in the analysis because of limited exposure above a reservoir clast hardness and degree of terrace weathering were generally consistent with progressive river downcutting the occurrence of faulted sediments however suggested that terrace elevations were modified locally by post depositional tectonic movements which may explain why probable younger terraces in some sectors of the mino river are at higher elevations than older terraces in adjacent sectors the equotip tester helped to resolve stratigraphic uncertainties and to assign deposits to specific terrace levels and was found to be a useful tool to distinguish and correlate river terraces

controls on the geotechnical response of sedimentary rocks to weathering weathering reduces the strength of rocks and so is a key control on the stability of rock slopes recent research suggests that the geotechnical response of rocks to weathering varies with ambient stress conditions resulting from overburden loading and or stress concentrations driven by near surface topography in addition the stress history experienced by the rock can influence the degree to which current weathering processes cause rock breakdown to address the combined effect of these potential controls we conducted a set of weathering experiments on two sedimentary lithologies in laboratory and field conditions we firstly defined the baseline geotechnical behaviour of each lithology characterising surface hardness and stress strain behaviour in unconfined compression weathering significantly reduced intact rock strength but this was not evident in measurements of surface hardness the ambient compressive stress applied to samples throughout the experiments did not cause any observable differences in the geotechnical behaviour of the samples we created a stress history effect in sub sets of samples by generating a population of microcracks that could be exploited by weathering processes we also geometrically modified groups of samples to cause near surface stress concentrations that may allow greater weathering efficacy however even these pronounced sample modifications resulted in insignificant changes in geotechnical behaviour when compared to unmodified samples the observed reduction in rock strength changed the nature of failure of the samples which developed post peak strength and underwent multiple stages of brittle failure although weakened these samples could sustain greater stress and strain following exceedance of peak strength on this basis the multi stage failure style exhibited by weaker weathered rock may permit smaller magnitude higher frequency events to trigger fracture through intact rock bridges as well as influencing the characteristics of pre failure deformation these findings are consistent with patterns of behaviour observed in field monitoring results

a new technique for non destructive field measurement of rock surface strength an application of the equotip hardness tester to weathering studies tafone like depressions have developed on the aoshima sandstone blocks used for a masonry bridge pier in the coastal spray zone a thin layer of partial granular disintegration was found on the surface in depressions to evaluate quantitatively the strength of the thin weathered layer the hardness was measured at the surface of the sandstone blocks using both an equotip hardness tester and an l type schmidt hammer comparison of the two testing results indicates that the equotip hardness value is more sensitive in evaluating the strength of a thin layer of weathered surface rock than the schmidt hardness value by applying two methods i e both the repeated impact method and the single impact method the equotip tester can evaluate the strengths of fresh internal and weathered surficial portions of rocks having a thin weathering layer comparison of the two strengths enables evaluation of strength reduction due to weathering copyright 2007 john wiley sons ltd

structural evolution of the piqiang fault zone nw tarim basin china abstract the piqiang fault is a prominent strike slip tear fault that laterally partitions the keping shan thrust belt in the nw tarim basin china in satellite images the piqiang fault appears as a sharp nw trending lineament that can be traced for more than 70 km it is oblique to the general structural trend of the thrust belt and subparallel to the thrust transport direction this paper presents a structural analysis of the piqiang fault based on satellite image interpretation and field data a net loss of late paleozoic sediment across the fault zone implies that it was initiated as a major normal fault during the early permian and corresponds to widespread extension and magmatism during this period differential erosion across the fault resulted in the subsequent removal of sediment from the east relative to the west during the middle to late cenozoic contraction of the nw tarim basin and the formation of the keping shan thrust belt resulted in reactivation of the piqiang fault as a strike slip tear fault the fault has accommodated lateral differences in thrust density and spacing which have arisen due to the abrupt pre existing change in stratigraphic thickness across it the piqiang fault provides an insight into the formation of oblique strike slip tear faults in contractional belts and demonstrates the importance of inherited basement structures in such settings

integrating structure from motion photogrammetry into rock weathering field methodologies despite recent rapid advances in the field of structure from motion sfm photogrammetry the use of high resolution data to investigate small scale processes is a relatively underdeveloped field in particular rock weathering is rarely investigated using this suite of techniques this research uses a combination of traditional non destructive rock weathering measurement techniques rock surface hardness and sfm to map deterioration and loss of cohesion of the surface using 3 dimensional data the results are used to interpret weathering behaviour across two different lithologies present on the site namely shale and limestone this new approach is tested on seven sites in longyearbyen svalbard where active weathering of a rock surface was measured after 13 years of exposure to extreme temperature regimes and snow cover the surface loss was quantified with sfm and combined with rock surface hardness measurement distributions extrapolated in gis the combined results are used here to quantify the difference in response of both lithologies to these extreme temperatures this research demonstrates the potential for further integration of sfm in rock weathering research and other small scale geomorphological investigations in particular in difficult field conditions where portability of field equipment is paramount

rock protecting seaweed experimental evidence of bioprotection in the intertidal zone biogeomorphological processes are an important component of dynamic intertidal systems on rocky shores the direct contribution of microorganisms plants and animals to weathering and erosion is well known there is also increasing evidence that organisms can alter rock breakdown indirectly by moderating temperature and moisture regimes at the rock air interface these influences have been purported to represent mechanisms of bioprotection by buffering microclimatic fluctuations associated with weathering processes such as wetting and drying and salt crystallization however virtually nothing has been done to test whether microclimatic buffering translates to differences in actual rock breakdown rates here we report a preliminary laboratory experiment to assess how an artificial canopy chosen to represent seaweed affects mechanical rock breakdown using a simplified and accelerated thermal regime based on field data from a rocky shore platform in southern england uk we find that breakdown mineral debris release of mudstone covered with a canopy is reduced by as much as 79 relative to bare rock after around 100 thermal cycles reduction in rock surface hardness measured using an equotip device was also greater for bare rock 17 compared to covered rock 10 over this period measurements of salt crystal formation indicate that the mechanism driving these differences was a reduction in the frequency of crystallization events via moisture retention and shading of the rock surface copyright 2015 john wiley sons ltd

the weathering of granitic rocks in a hyper arid and hypothermal environment a case study from the sor rondane mountains east antarctica abstract weathering processes in hyper arid and hypothermal environments are key to our understanding of geomorphological processes and landscape evolution in antarctica and likely on mars a number of studies have focused on the weathering of basaltic rocks in antarctica however the nature of the weathering of quartzofeldspathic rocks a common rock type on earth has received less attention and remains unclear here we explore the weathering of granitic rocks which are a type of quartzofeldspathic rock and the associated weathering products in the sor rondane mountains of east antarctica to obtain quantitative information regarding the physical and chemical weathering of granitic rocks in hyper arid and hypothermal environments various petrological techniques were used to analyze the physical and chemical weathering of the rocks loss on ignition loi values and the major element composition obtained from the crust and core of the rock samples indicate that the production of hydrous clay minerals in this area is very limited examination under a microscope together with laser raman microspectroscopy of thin sections from the crust and core of the samples indicate that goethite grains form mainly in veins within the crust which is consistent with the contrasts seen in the fe 3 fe 2 and color strength index csi values obtained from the core and crust a negative correlation between rock hardness and degree of weathering as measured from the crust of the samples indicates that the weathered samples are softer than the core this indicates that cracking and subsequent vein formation cause a reduction in the hardness of the crust and an increase in staining via the formation of goethite grains that develop in the veins furthermore electron probe microanalyzer epma analysis indicates that the original fe ti oxide grains are altered by weathering and change to hematite or a non stoichiometric fe ti compound associated with ilmenite grains in the case of a greater degree of weathering these findings reveal that the weathering of granitic rocks in a hyper arid and hypothermal environment is controlled mainly by oxidation including iron hydroxide formation in veins formed by the thermal expansion and contraction of rock forming minerals frost shattering and or salt fretting and fe ti oxide alteration in the rock interior importantly these physical and chemical weathering processes are unlikely to require a liquid water supply from the environment snow or vapor hence the restricted supply of liquid water and salt is the most probable explanation for the extremely slow weathering rates in the sor rondane mountains we therefore conclude that the weathering process observed in this area is a typical feature of quartzofeldspathic rocks under hyper arid and hypothermal conditions and potentially also on mars in situ color measurements essentially express the amount of iron hydroxide on the rock surface thus in situ and satellite measurements of the color of exposed rocks in antarctica can potentially provide quantitative information regarding the degree of weathering

the influence of rock mass strength on glacial valley cross profile morphometry a case study from the southern alps new zealand the erosional morphology in the vicinity of the main divide of the southern alps and fiordland new zealand appears to be a product of the interaction between alpine fault induced tectonic processes rock mass strength of the uplifted and eroded bedrock and the processes acting to denude the developing mountain landscape the magnitude of the effects of glacial erosion on the landscape is directly controlled by the size and physical properties of the glaciers whilst the form of the trough is a direct consequence of the rock mass strength rms properties of the slope rock realistic models of development of the cross profile shape of glacial valleys must take into consideration the rms properties of the eroded substrate

investigations into the relationship between changes in internal moisture regimes and rock surface deterioration in cavernous sandstone features cavernous features commonly develop in sandstone but their development over time remains enigmatic it has been suggested that moisture movements within the rock mass play a key role in the location development and dynamics of cavernous features in this research the role of internal moisture movement is tested through monitoring moisture and surface deterioration dynamics in april 2008 and april 2009 within two large cavernous features mega tafoni in the golden gate highlands national park south africa gghnp data are presented from surveys of internal moisture using electrical resistivity tomography ert surface moisture using a protimeter and deterioration using surface hardness as recorded with an equotip as a proxy for surface deterioration across five 2 45 m long transects in addition a high resolution temperature record is presented to assess the influence of micro climates within the caverns the results indicate consistency in the gross spatial pattern of moisture flow within the rock mass over a one year period but significant changes in mean moisture contents and in the fine detail of moisture patterning some noticeably weakened areas had developed within the central parts of the cavernous features often linked to wetter subsurface conditions supporting the theory that core softening is a main driver of cavernous feature formation however in some areas surface hardening is also found to be associated with wetter subsurface conditions supporting the theory that case hardening is a main driver of cavernous feature formation in addition the presence of well established biofilms suggests an even more complex interaction between moisture surface development and biological activity a model is presented therefore which integrates this paradox by proposing a non linear relationship between moisture dynamics facilitation of biofilm formation and deterioration within cavernous features

an assemblage of macroscopic and diversified carbonaceous compression fossils from the tonian shiwangzhuang formation in western shandong north china abstract macroalgae play a crucial ecological and biogeochemical role in modern marine ecosystems although eukaryotic algae have a deep history within the precambrian most pre cryogenian alga fossils are microscopic and macroalga fossils are poorly documented during this period here we report a well preserved assemblage of macroscopic and diversified carbonaceous compression fossils from the tonian shiwangzhuang formation in western shandong north china this assemblage consists of seventeen distinct morphotaxa including eleven macroalgae showing remarkable taxonomic diversity that is more diverse than many other tonian macrofossil assemblages all over the world three taxa from the shiwangzhuang assemblage show evidence of simple multicellularity with two of them consisting of giant cells and comparable to giant celled green algae and seven taxa with diagnostic transverse annulations are likely coenocytic algae the shiwangzhuang assemblage indicates that some eukaryotic clades had achieved macroscopic growth through simple multicellularity or coenocytism paving the way either ecologically or phylogenetically for the eventual appearance of complex multicellularity in addition there are some biostratigraphically significant genera including the chuaria tawuia and sinosabellidites protoarenicola pararenicola assemblages indicating a tonian age for the shiwangzhuang formation this study also suggests that the tonian diversity of multicellular or coenocytic macroalgae is probably underestimated pending for a systematic and thorough investigation of tonian macroscopic carbonaceous compressions macroalgae may have an initial ecological expansion at least locally if not globally in the tonian period

rates of weathering and temporal changes in strength of bedrock of marine terraces in boso peninsula japan the weathering rates of bedrock of the dated erosional marine terraces were examined for two definitions 1 the rates at which the thicknesses of weathered zones with different strengths increase with weathering time and 2 the rates at which the strength of weathered materials at an arbitrary depth decrease with time the bedrock of terraces in the study area consists mainly of tertiary sandstone and mudstone the weathering profiles were observed from drill cores on three levels of terrace surfaces i e 2850 290 and 70 years b p in the emergence age of terraces which is regarded as the weathering time of bedrock the degree of weathering grade was described by the residual strength ratio which is defined as the ratio of the needle penetration hardness of weathered part to that of fresh part of bedrock the weathering rates of the first definition do not decrease monotonically but decelerate logarithmically with time zones with lower weathering grades have faster weathering rates than those with higher weathering grades with respect to the weathering rates of the second definition mudstone starts to weather earlier than sandstone but is exceeded by the latter after a certain time has elapsed because mudstone has a higher slaking susceptibility

thermal stress induced microcracking in building granite abstract microcracking induced by wide fluctuations in temperature affects granite quality and durability making the stone more vulnerable to decay determining the extent of that effect is not always straightforward however given the excellent durability of these materials four types of construction granite quarried in the region of madrid spain and frequently used in both the built heritage and in de novo construction alpedrete cadalso de los vidrios colmenar viejo and zarzalejo were exposed to 42 thermal cycles 105 20 c une en 14066 2003 petrographic and petrophysical properties were analysed using both destructive and non destructive techniques microcracking generated in the granite stones by 42 thermal cycles had barely any impact on their petrophysical properties which are the parameters normally assessed to establish material quality and durability their petrographic properties which are not generally assessed in this type of studies were affected however this study contends that petrographic analysis is needed to objectively quantify the actual quality and durability of the most highly resistant materials when petrophysical studies are inconclusive petrographic and fluorescence microscopy along with fractography are among the most prominent techniques for petrographic exploration thanks to the deployment of these techniques mineral microcracking could be monitored throughout the present tests conducted the microscopic findings revealed substantial micro textural and microstructural change in and around the granite minerals which play a prominent role in decay the findings showed that pre existing microcracks coalesced and generated further microcracking as decay progressed microcracking was most intense in zarzalejo granite due to its textural characteristics determined by its high feldspar content microscopic observation revealed that the microstructure of feldspar minerals with their crystallographic anisotropies and secondary mineral phases favoured microcrack development zarzalejo granite exhibited lower quality and durability than colmenar viejo and cadalso de los vidrios granites which were more resistant to heat treatment

structural inheritance in mountain belts an alpine apennine perspective abstract the geological structure of continental lithosphere shows complex variety that is inherited into orogenic belts and influences the localization and amplification of contractional structures during mountain building in the alpine apennine sector together with other sectors of the tethyan orogenic system the pre orogenic crustal template can include arrays of extensional faults other faults can form adjacent to the evolving mountain belt and subsequently become incorporated as the thrust belts migrate into their forelands while in some areas these inherited features may simply reactivate under inversion more commonly faults show complex partial reactivation structures in volumes of distributed strain faults may serve to nucleate large scale buckle folds for example along basement cover interfaces these different patterns of basement reactivation may reflect spatially varying strength depth profiles in continental lithosphere that are themselves inherited from spatially distinct geological histories even when not themselves reactivating basement faults can control deformation in the overlying sedimentary cover by offsetting otherwise regionally extensive detachment horizons the 3d form of thrust systems can be strongly compartmentalized by pre existing cross faults such as the oblique lineaments of the apennines on a large scale the distribution of pre existing faults and other weaknesses may affect the propensity for orogenic contraction in basement and therefore directly control larger scale tectonic processes in the central mediterranean the evolution of slab roll back and the related growth of overlying extensional basins e g tyrrhenian sea may be strongly modulated by the distribution of rift related weak zones in the adjacent continental crust the subduction of continental crust will strongly depend on the inherited structure of this crust specifically the distribution of deep crust of basic composition this develops relatively higher densities associated with eclogite metamorphism which act in turn to reduce the buoyancy of thickened continental crust that otherwise serves to inhibit further shortening investigating all these aspects from the scale of bulk crustal compositions to the geometry timing and strength of earlier fault zones preserved in orogenic belts requires the integration of substantial multidisciplinary geological data sets the extent to which continental orogenic belts represent the amplification of inherited geological heterogeneities as opposed to self ordered phenomena modulated by the syntectonic environment remains unclear

macroscopic worm like body fossils from the upper precambrian 900 700 ma huainan district anhui china and their stratigraphic and evolutionary significance abstract abundant and varied macroscopic worm like body fossils from the late precambrian liulaobei formation huainan group and the jiuliqiao formation feishui group in the huainan district northern anhui province china are further investigated through this progress report after the initial discovery by zheng wenwu and a recent study by wang guixiang sinosabellidites zheng in the liulaobei formation is a worm like organism of questionable metazoan origin it has merely a superficial resemblance with the tubes of late vendian early cambrian true sabelliditida but has much in common with the accompanying macroscopic algal remains of tawuia hofmann both pararenicola wang and protoarenicola wang are representatives of primitive worm like animals in the jiuliqiao formation their macroscopic size elongate cylindrical body anterior aperture and apparatus prominent and elastic annulations are characteristic for their metazoan origin although they lack sufficient evidence for their definite relationship with any known kind of living worms the liulaobei formation and the jiuliqiao formation are dated at about 850 ma and 740 ma respectively regional geology and stratigraphic correlation and the occurrence of the distinctive chuaria tawuia assemblage suggest a time range between less than 900 ma and over 700 ma for the whole shallow water marine sedimentary sequence of the huainan and feishui groups this latter group is disconformably covered by the drop stone facies diamictites and tillites of the late precambrian luoquan glaciation apart from the enigmatic sinosabellidites both pararenicola and protoarenicola are claimed to be the oldest multicellular animals so far discovered in the world and the first reliable evidence for the pre ediacarian evolutionary history of manifest metazoan life

timing of the tianshan mountains uplift constrained by magnetostratigraphic analysis of molasse deposits abstract the tianshan mountains lie in the actively deforming part of the india asia collision zone the thrust faulting and folding of the neogene and quaternary sediments forming linear roughly east west anticlines at the northern and southern borders of the orogenic belts indicate crustal shortening and thickening in late cenozoic time detailed magnetostratigraphic studies of the molasse deposits of the folded neogene and quaternary strata in the northern edge of the tianshan mountains indicate that the onset of uplift occurred at 7 ma deposition of the thick conglomerates between 7 and 2 58 ma in the studied region was mainly in response to the tectonic uplift while the accumulation of the early pleistocene conglomerates xiyu formation was mostly controlled by both tectonics and climatic cooling our results indicate that the present high relief of the tianshan mountains is the result of two dominant phases of uplift occurring at about 7 2 58 ma and the early pleistocene

microfossils from the lower mesoproterozoic kaltasy formation east european platform abstract basinal shales of the lower mesoproterozoic kaltasy formation sampled from three boreholes drilled into the southeastern east european platform russia contain abundant and moderately well preserved microfossils 34 distinct entities have been identified most assigned to simple sphaeromorphic or small filamentous taxa found widely and characterized by long stratigraphic ranges ornamented microfossils found in coastal successions of other lower mesoproterozoic basins are absent but large filamentous microfossils interpreted as possible benthic photosynthetic eukaryotes are recorded drawing comparisons to relatively deep water shales in siberia in overall aspect the kaltasy microfossils are consistent with other broadly coeval assemblages but they highlight the importance of environment as well as age in determining the distributions of remains that record the early diversification of marine eukaryotes rectia magna is described as a new species

quantification of rock control in geomorphology abstract rock control the influence of rock properties on landform development has for long been a relatively under researched topic but numerous techniques have been developed especially by geotechnical engineers and stone conservationists that are now being applied to geomorphological issues by geomorphologists these techniques range in scale from the quantification of major discontinuities through to analysis of micro pores rock control studies that have taken place over the last few decades have contributed important insights into our understanding of such diverse phenomena as 1 river terraces bedrock channel forms and gradients pot hole development drainage density and gully badland development 2 slope forms and failures especially with respect to rock mass strength 3 the form of glacial troughs and of subglacial erosional landforms 4 weathering controls on rock durability and the association of weathering with porosity 5 classic karst features including various types of karren 6 sandstone landforms 7 inselbergs and tors and 8 cliffs and shore platforms

late paleozoic strike slip shear zones in eastern central asia nw china new structural and geochronological data 1 new structural studies and 40ar 39ar dating in northwest china provide information about late paleozoic strike slip motions subsequent to accretional events which built eastern central asia during the paleozoic two principal areas were affected by these large transcurrent motions first in the tianshan range main east west ductile shear zones are dextral and coeval with an eastward decreasing greenschist retrograde metamorphism associated biotites give ages ranging from 290 ma to 245 ma the earlier n110 shearing occurred in western tianshan while the last one dextral in whole tianshan occurred 250 245 myr ago second in the chinese altay region several nw se shear zones structured the area the main motion is sinistral and occurred along the erqishi zone at 280 290 ma it is followed by a complex succession of dextral and sinistral shearing episodes leading to the northwestward structuring dated at 245 ma of a metamorphic zone that was folded during a compressive event

magnetochronology of the upper cenozoic strata in the southwestern chinese tian shan rates of pleistocene folding and thrusting abstract the southwestern chinese tian shan of central asia is an actively deforming part of the indian asian collision system paleomagnetic investigations of two plio pleistocene terrestrial successions provide the first detailed magnetostratigraphy for the upper cenozoic strata in this region paleomagnetic samples were collected from 358 sites within the atushi formation and xiyu formation across the atushi talanghe anticline near atushi thermal demagnetization behavior reversal and fold tests of paleomagnetic stability indicate that the characteristic remanence directions were acquired before tilting and folding of the strata a composite magnetostratigraphic section for this sequence correlates with the mammoth subchron to the jaramillo subchron between 3 3 and 1 07 myr of the geomagnetic polarity timescale of cande and kent j geophys res 100 1995 6093 6095 the mean declination 349 3 in the boguzihe section indicates a counterclockwise vertical axis rotation 11 2 during the past 1 4 myr the conglomeratic xiyu formation is time transgressive along its progradational contact with the underlying atushi formation across a map distance of 6 km the basal contact ranges from less than 1 0 myr in the ganhangou section to 1 9 myr in the boguzihe section to the southwest and to 2 8 myr on the northwest limb of the anticline northeastward lateral propagation and growth of the atushi talanghe anticline initiated at 1 4 myr in the boguzihe and 1 2 myr in the ganhangou the cross section in the boguzihe provides a conservative maximum estimate of shortening rate of 3 3 4 4 mm yr and uplift rate of 3 mm yr this rate represents about half of the geodetically determined shortening rate between the northern tarim basin and the kyrgyz tian shan wang et al acta seismol sin 22 2000 263 270 reiger et al earth planet sci lett 191 2001 157 165 during fold growth over the past 1 4 myr the crest of the atushi talanghe anticline eroded at an average rate of 2 6 2 7 mm yr

linking the sulu uhp belt to the korean peninsula evidence from eclogite precambrian basement and paleozoic sedimentary basins abstract considerable debate on whether and how the sulu orogenic belt extends eastward to the korean peninsula has remained over the past decade new results reported here include the following 1 an eclogite and retrograded eclogite bearing complex hongseong complex is discovered in south korea in which the eclogite occurs as lenses in circa 810 820 ma granitic gneiss shrimp zircon dating of the eclogite yields 230 ma for the metamorphic age and 880 ma for the protolith age 2 the basement of the rangnim gyeonggi and yeongnam massifs have affinities to the basement of the north china block ncb however the gyeonggi massif encloses a minor amount of large or small slabs of the hongseong complex that are similar to the rocks of the sulu belt 3 two main paleozoic basins within the rangnim and gyeonggi massifs have a similar paleozoic tectono stratigraphy to the ncb 4 the imjingang and ogcheon belts do not exhibit any metamorphic characteristics of collisional orogenic belts based on these facts we propose a crustal detachment and thrust model and suggest that the collision belt between the yangtze block yb and ncb sino korea craton is preserved along the western margin of the korean peninsula the lower part of the uhp metamorphosed lithosphere of the yb was subducted under the korean peninsula and not uplifted to the surface the lower crust of the yb the hongseong complex was detached from the subducted lithosphere and thrust over the korean peninsula and inserted into the basement rocks of the gyeonggi massif the upper crust of the yb possibly was detached from the lower crust and overthrusted along the honam and chugaryong shear zones the imjingang and ogcheon belts possibly represent the detached upper crust of yb and their present occurrences are controlled by a mesozoic strike slip shear structure all these detached lower and upper crustal slabs were strongly deformed during the late jurassic and early cretaceous tectonic event leading to their present geological distribution and characteristics

influence of inherited taper on structural variability and conglomerate distribution cordilleran fold and thrust belt western united states north south changes in thickness of the prethrust stratigraphy of the north american cordillera within the united states controlled kinematic development of the late mesozoic sevier fold and thrust belt variation in stratigraphic thickness determined the initial slope o of the basal decollement beneath the thrust wedge as predicted by critical wedge theory segments of the sevier thrust belt with initially thick precambrian and paleozoic stratigraphic sections are structurally simple and are composed of few thrust sheets segments with thin prethrust stratigraphy and comparably low values of o are intensely imbricated the difference in structural style resulted because wedge segments with higher values of o required less internal deformation to build and maintain the critical taper required for thrust wedge advance transverse structural zones across which kinematic style differed formed at the terminations of thrust belt segments and controlled the locations of long lived antecedent drainage systems that transported gravel to the foreland therefore along strike changes in prethrust stratigraphic thickness resulted in an observed disjunct distribution of conglomerate in synorogenic deposits of the thrust wedge and foreland basin

a rock surface microweathering index from schmidt hammer r values and its preliminary application to some common rock types in southern norway an index of the degree of rock surface microweathering based on schmidt hammer r values is developed for use in the field without laboratory testing a series of indices i2 to in where n is the number of successive blows with the hammer is first proposed based on the assumption that the r values derived from successive impacts on the same spot on a weathered rock surface converge on the value characteristic of an unweathered surface of the same lithology of these indices the i5 index which measures the difference between the mean r value derived from first and fifth impacts as a proportion of the mean r value from the fifth impact is regarded as optimal use of fewer impacts e g in an i2 index underestimates the degree of weathering whereas use of more impacts e g in an i10 index makes little difference and is therefore inefficient and may also induce an artificial weakening of the rock field tests of these indices on weathered glacially scoured bedrock outcrops of nine common metamorphic and igneous rock types from southern norway show however that even after ten impacts successive r values fail to approach the values characteristic of unweathered rock surfaces e g bedrock from glacier forelands and road cuttings an improved i5 index is therefore preferred in which the estimated true r value of an unweathered rock surface is substituted weathered rock surfaces exposed to the atmosphere for 10 000 years in southern norway exhibit i5 indices of 36 57 values that reflect a similarly high degree of weathering irrespective of the rock type

application of an s shaped curve model to the temporal development of tafoni of salt weathering origin to describe temporal change in tafone development an s shaped curve equation is proposed z zc 1 n 1 exp t n exp 1 1 n t where z is observed tafone depth zc is ultimate tafone depth t is time and n and are constants the applicability of this model is examined using tafone data selected from seven sites which are categorized into three different salt weathering environments a spray splash dominant occasionally wave affected supra tidal zone aerosol affected coastal regions and inland desert areas the results indicate that the equation can well describe tafone development in each of these environments an investigation based on the values of n and determined through a best fit of the equation to the data suggests that n characterizes site specific environmental conditions and reflects the magnitude of factors controlling the recession mechanism of tafone surfaces it is found that 1 the maximum rate of tafone growth dramatically decreases from supra tidal through coastal to desert environments and 2 the growing mode of tafoni is different depending on the environmental settings the erosional force to facilitate the development of tafoni at supra tidal sites is estimated to be about 400 times greater than that in the general coastal area copyright 2011 john wiley sons ltd

neoproterozoic microfossils from the margin of the east european platform and the search for a biostratigraphic model of lower ediacaran rocks abstract a ca 600 m thick siliciclastic succession in northern russia contains abundant and diverse microfossils that document early to middle ediacaran deposition along the northeastern margin of the east european platform the vychegda formation is poorly exposed but is well documented by a core drilled in the timan trough region kel tminskaya 1 borehole vychegda siliciclastics lie unconformably above tonian to lower cryogenian strata and below equivalents of the late ediacaran redkino succession that is widely distributed across the platform the basal 10 m of the formation preserve acritarchs and fragments of problematic macrofossils known elsewhere only from pre sturtian successions in contrast the upper nearly 400 m of the succession contains abundant and diverse large acanthomorphic acritarchs attributable to the ediacaran complex acanthomorph palynoflora ecap this distinctive set of taxa is known elsewhere only from lower but not lowermost ediacaran rocks in between lies an additional assemblage of relatively simple filaments and stratigraphically long ranging sphaeromorphic acritarchs interpreted as early ediacaran in age bearing in mind that knowledge of late cryogenian post strurtian pre marinoan microfossils is sparse the vychegda record is consistent with data from australia and china which suggest that diverse ecap microfossil assemblages appeared well into the ediacaran period accumulating paleontological observations underscore both the promise and challenges for the biostratigraphic characterization of the early ediacaran period

nail penetration test for determining the uniaxial compressive strength of rock abstract we offer a new and practical index test method the nail penetration test npt to estimate the ucs of intact rocks to be used as alternative to the point load test plt or schmidt rebound hammer test srh the major tools used in the investigation include a gasnailer with 130 j power and its nails ranging from 25 to 60 mm in length the study material covers 65 rock blocks of gypsum tuff ignimbrite andesite sandstone limestone and marble for the npt five nail shots were performed on each block sample and the average value was obtained two to three uniaxial compression tests were carried out on each specimen ten impacts were applied on rock blocks by using both the l and n types of srh regarding the plt either 10 axial or 10 block tests was applied on each rock type the average nail penetration depths were correlated with the ucs is 50 and rebound number for both types of the srh also the measured ucs values were compared with those obtained from the empirical relationships using the data from the npt plt and srh it was found that the npt provides better estimates for ucs than the plt or srh particularly applicable to weak to very weak rocks the npt is capable of indirectly estimating the ucs of intact rocks up to 100 mpa the test is proposed for use in mainly in situ applications

classification of rock weathering at writing on stone provincial park alberta canada a study in applied geomorphology at writing on stone provincial park in southern alberta canada weathering is causing deterioration and loss of archaeologically important indian rock art a procedure devised for the use of park personnel identified four classes of weathering ranging from largely unweathered rock to severely weathered the technique employed simple visual qualitative assessment and photo interpretation of 50 sample sections of sandstone cliff face covering a total area of 354 m2 schmidt hammer tests indicated large variations in rock strength and provided a numerical basis for the visual assessment about 43 per cent of the cliffs are severely to completely weathered 41 per cent show moderate weathering

relatively recent construction of the tien shan inferred from gps measurements of present day crustal deformation rates the tien shan a high seismically active intracontinental mountain belt 1 000 2 000 km north of the himalaya has grown as a result of india s collision with asia1 the crustal shortening 200 50 km refs 2 3 and thickening that gave rise to the tien shan accommodates only a small fraction of india s total penetration into asia 2 000 3 000km and the temporal relationship of deformation in this belt to the india asia collision remains unclear here we report geodetic measurements of the tien shan using the global positioning system gps that indicate that the current crustal shortening rate is nearly half of india s convergence rate with eurasia in this area4 we infer a total shortening rate for the tien shan of 20 mm yr 1 which is approximately twice that inferred previously from the extrapolation of slip rates in the holocene3 and earthquake induced displacements during this century5 suggesting that the rate of mountain building in this region has accelerated several fold since the onset of collision 50 55 myr ago6 7 if as we argue the current shortening rate can be extrapolated to geological timescales then our results suggest that most of the tien shan has been constructed during the past 10 myr perhaps in response to an increased horizontal force following an abrupt rise of the tibetan plateau8 9

paleozoic accretion and cenozoic redeformation of the chinese tien shan range central asia the tien shan range in central asia contains two late paleozoic sutures the older southern suture marks the collision of a passive margin at the north of the tarim block and an active continental margin subduction under the latter was to the north the younger northern suture separates a northern carboniferous island arc from an active continental margin developed over a south dipping subduction zone the subduction direction under the island arc is unknown mesozoic elastics were deposited over the doubly sutured orogen rate and energy of sedimentation waned until deposition of oligocene conglomerates above a regional unconformity interpreted as marking the onset of deformation induced by the india asia collision molasse deposition accelerated in pliocene and quaternary time and deposition continues today as active thrusts generate relief paleozoic structures control the gross divergence of cenozoic thrusts across the orogen

neoproterozoic 900 ma sariwon sills in north korea geochronology geochemistry and implications for the evolution of the south eastern margin of the north china craton article the sariwon sills are distributed in the pyongnam basin at the center of the korean peninsula eastern part of the north china craton these sills are up to 150 m in thickness and up to more than 10 km in length baddeleyite grains separated from a 50 m thick sill give a sims 206 pb 207 pb age of 899 7 ma mswd 0 34 n 14 which is interpreted to be the crystallization age of this sill zircon grains from the same sill gives a lower intercept u pb age of 400 ma which is likely a close estimation of the greenschist facies metamorphism of this sill the sariwon sills are dolerites and have tholeiitic compositions they show enrichment of light rare earth element concentrations la ybn 1 4 2 8 and are slightly depleted in high field strength elements e g nb zr and ti in comparison to neighboring elements on the primitive mantle normalized spidergram the whole rock endt t 900 ma values are around 2 whereas in situ ehft t 900 ma values from zircon grains vary from 25 to 8 they are similar to the coeval sills in other parts of the north china craton e g the chulan sills xu huai basin shandong peninsula and the dalian sills lv da basin liaodong peninsula these sills possibly originated from a depleted mantle source e g asthenosphere rather than from the ancient lithospheric mantle of the north china craton and have experienced significant assimilation of lithospheric materials the strata and sills in the xu huai lv da and pyongnam basins are comparable moreover the three basins are geographically correlatable based on neoproterozoic geographical reconstruction we therefore propose that there is a xu huai lv da pyongnam rift system along the south eastern edge of the north china craton during neoproterozoic 900 ma with the closure of the rift at 400 ma as a result of a continent margin process it is possible that this southeastern margin of the ncc did not face the inland in the configuration of the supercontinent rodinia