lithofacies associations and evolution of the volcanic host succession to the minifie ore zone ladolam gold deposit lihir island papua new guinea the 46 million ounce ladolam gold deposit the largest alkalic epithermal gold deposit in the world in terms of contained gold is composed of four ore zones minifie lienetz kapit and coastal this detailed lithofacies study of the minifie ore zone recognized three evolutionary stages 1 volcanosedimentary strata part of an alkalic composite volcanic island 2 a porphyry style breccia dike and 3 epithermal style breccias the plio pleistocene volcanosedimentary stratigraphy reflects the transition from subaerial deposition of pyroclastic surge deposits close to vent to a subaqueous quiet depositional environment into which a cryptodome was emplaced the stratigraphy is predominantly composed of polymictic matrix supported breccia and sandstone interbedded with lavas and shallow intrusions the minifie strata have a shallow southward dip as a result of quaternary uplift overprinting the volcanosedimentary stratigraphy are three hydrothermally cemented breccia facies one deposited in the porphyry environment and two deposited in the epithermal environment porphyry style alteration assemblages and a 3 to 5 m wide biotite k feldspar calcite anhydrite cemented breccia dike are focused around the central minifie shear fault the porphyry alteration assemblages are overprinted by shallow level and deeper level epithermal style features the deeper level below the present mining surface 140 m below sea level epithermal vein stockwork is composed of quartz calcite adularia anhydrite cemented breccias and shallowly northward to near horizontal dipping veins that have gold grades of 1 to 60 g t au shallow level epithermal facies adularia quartz pyrite cemented breccias veins and associated alteration host the bulk mineable gold ore and typically yield 4 g t au over 12 m blast hole samples

lithological control on the elevation of shore platforms in a microtidal setting the shore platforms on shag point southern new zealand are quasi horizontal surfaces and are developed between supratidal and low water spring levels a range of morphologies occur with more exposed platforms having a distinct low tide cliff in contrast to low tide surfaces where the seaward edge is buried beneath rubble and macro algal growth the platforms range in width from 20 to 80 m and are eroded into late cretaceous early tertiary fine marine sandstones and mudstones shore platforms have formed in two principal lithological units a homogeneous unit that is characterized by few discontinuities and a fractured unit with joints spaced about 0 5 m apart rock hardness is low in both units l type schmidt hammer rebound values of 31 4 and there is little systematic variation in values between the two units in which platforms have developed case hardened concretions within the sandstone are significantly harder than surrounding rock and cause local relief of metre scale as the spherical diagenetic features are eroded from the bedrock they do not however appear to affect broad scale platform geometry joints within the bedrock are a primary control on platform elevation platforms formed in jointed rock occur at the lower portion of the intertidal zone in contrast to platforms formed in unjointed bedrock in which horizontal surfaces occur at or above mean high water spring tide level rock structure therefore appears to be the primary determinant factor of platform geometry at shag point copyright 2006 john wiley sons ltd

evidence for bacterial degradation of hydrocarbons in uranium deposits the biodegradation of free hydrocarbons migrated in reservoir faaes has often been observed in petroleum exploration this bacterial alteration is characterized by the progressive removal of different classes of hydrocarbons one of the most important consequences of biodegradation is the reduction of sulphate as noted in several pb zn deposits biodegradation of oils spatially associated with uranium deposits has also been observed in lodeve france grand canyon arizona usa temple mountain utah usa and leads to the transformation of fluid oils into solid bitumens within this study emphasis has been laid on the relationships between the effects of biodegradation on organic matter oxidation or aromatization and the nature of aqueous solutions analysed in fluid inclusions trapped in authigenic minerals different mechanisms are proposed to explain the transformations of organic matter during biodegradation and their possible links with ore forming processes

improved schmidt hammer exposure ages for active and relict pronival ramparts in southern norway and their palaeoenvironmental implications abstract eight pronival protalus ramparts from alpine southern norway were dated using schmidt hammer exposure age dating shd based on local high precision linear calibration equations shd ages were 1355 1240 to 815 1000 years for three active ramparts and 8730 1050 to 14 635 1060 years for five relict ramparts different parts of the same rampart yielded ages that were in generally good agreement r value frequency distributions enabled the identification single age and mixed age boulder populations and the differentiation of active and relict rampart surfaces the relict ramparts are located outside younger dryas glacier limits and probably formed over a period of 6000 years between deglaciation following the last glacial maximum of the late weichselian 18 000 years ago and the end of the younger dryas 11 700 years ago at that time glacial debuttressing and permafrost degradation apparently enhanced the release of rock debris from rock faces to the ramparts the active ramparts which are located in areas deglaciated after the younger dryas are relatively uncommon in the study area due to diminished paraglacial effects and limited debris supply associated with seasonally frozen ground during the holocene thus the legacy of glaciers glacier permafrost interaction and the specific type of periglacial environment must all be considered when assessing the palaeoenvironmental and palaeoclimatic significance of pronival ramparts

breccias and ores part 1 history organization and petrography of breccias abstract although the term breccia is one of the oldest rock names still in use and proliferating in its application a satisfactory definition remains problematic and an overall classification of breccias is non existent the names of breccia varieties several hundred please the heart rather than the computer and there is little interdisciplinary correlation among the more than fifty specialized schools of breccia study this contribution reviews briefly the history of breccia research and provides a list of the present study trends complete with references with emphasis on ore associated breccias wherever possible conventional breccia definitions and their shortcomings are discussed and a case is made for the introduction of the petrographic category of coarse fragmentites of which the typical sedimentary breccias and conglomerates as well as volcanic tectonic hydrothermal impact and other fragmental materials are members whether designated or not as breccia in the conventional literature this is followed by a proposed rational organization classification of coarse fragmentites and breccias based on the regime of formation and architecture fabric gefuge two fundamental end member sequences a b and a transitional suite c can be recognized a disaggregation fragmentites d breccias produced from a solid progenitor by increasing rate of fracturing expansion rotation mixing and attrition the transitional sequence is crackle mosaic rubble melange milled breccia b aggregation fragmentites a breccias generated by gathering aggregation and accumulation of originally dispersed fragments at the site of deposition these materials form a sequence ranging from tightly packed fragment supported matrix free fragmentites through matrix infilled matrix supported fragmentites to lonestone rocks c in transport fragmentites t breccias formed by redeposition of an aggregate gathered in an earlier phase of development as an a fragmentite or by transportation and redeposition of an advanced member i e rubble melange or milled fragmental aggregate of a d fragmentite examples of metallic mineralizations coeval with or superimposed on the fragmentite sequences are reviewed

revised palaeoclimatic significance of mueller glacier moraines southern alps new zealand a sequence of late holocene moraines on the foreland of the mueller glacier southern alps new zealand forms part of a local moraine age database used to establish a regional glacier chronology and subsequently to investigate potential intra hemispheric and global climate forcing mechanisms we present new sedimentological and geomorphological evidence that a set of these moraine ridges previously considered to represent individual advances constitutes a single moraine complex the mueller memorial moraine formed by supraglacial transport of a large volume of landslide debris to the glacier terminus because a moraine formed in this way is not necessarily associated with an advance triggered by a climate event we question the palaeoclimatic significance of the mueller memorial moraine as well as that of other moraines in comparable settings our findings suggest that the mode of formation and glacio dynamical context of moraines whose ages contribute to existing palaeoclimate reconstructions need to be re examined in order to assess the reliability of these reconstructions copyright 2015 john wiley sons ltd

formation of volcanic exhalative nickel sulfide deposits at a late proterozoic spreading ridge in the proto arabian shield field and petrologic studies indicate that the strata bound nickeliferous sulfide deposits of jabal mardah were formed contemporaneously with sedimentation of an active spreading ridge mineralizat

mineralization of breccia pipes in northern arizona the paleozoic sedimentary rocks on the colorado plateau of northern arizona are host to hundreds ofbreccia pipes the uranium and copper deposits in these breccia pipes transgress formation boundaries from the mississippian redwall limestone to the triassic chinle formation they are not classic breccia pipes in that there is no volcanic rock associated with them in time or space they are the result of solution collapse within the redwall limestone and stoping of the overlying strata the karst development in the redwall limestone began in the mississippian and apparently either continued to the triassic or was at least once again active during that time the mineralization apparently occurred shortly thereafter sometime during the mesozoic mining activity in breccia pipes of the grand canyon region began during the nineteenth century and continues today with the operation of the hack i ii and iii mines although the exploited commodity has changed from cu to u although small in size these pipes contain samples with up to 55 percent u 3 o 8 and can yield ore averaging between 0 30 and 0 60 percent u 3 o 8 mineralization at the surface commonly occurs within nodules and concretions associated with pyrite and goethite and along fractures while the primary ore of the unoxidized zones is commonly within a comminuted sandstone matrix surrounding breccia fragments of overlying formations the ore mineral is uraninite although associated with it are sphalerite galena chalcopyrite tennantite millerite siegenite and molybdenite some of the surface nodules are encrusted with malachite and are exceptionally enriched in ag pyrite is abundant and the organic carbon content of some rocks is high enough to suggest that it along with the pyrite may be a reductant for uranium in contrast it is possible if uranium were transported as a bicarbonate or carbonate complex that only a conduit of brecciated rock was necessary to release co 2 thus disrupting the equilibrium and allowing uraninite to precipitate an extensive suite of elements is significantly enriched in the mineralized rock ag as ba cd co cr cs cu hg mo ni pb sb se sr u v zn and the rare earth elements of these cu pb zn ag and particularly as appear to be the best geochemical indicators of mineralized pipes at present the origin of the mineralizing fluids is not known the lack of extensive silification within the breccia along with the 80 degrees to 173 degrees c fluid inclusion filling temperatures on sphalerite dolomite quartz and calcite suggests relatively low temperature mineralizing fluids although heated in excess of what would be expected from the normal geothermal gradient on the colorado plateau with the exception of the u mineralized rock the mineral assemblage and geochemistry is similar to mississippi valley type deposits

wind and wave influences on sea ice floe size and leads in the beaufort and chukchi seas during the summer fall transition 2014 sea ice floe size distribution and lead properties in the beaufort and chukchi seas are studied in the summer fall transition 2014 to examine the impact on the sea ice cover from storms and surface waves floe size distributions are analyzed from medea landsat8 and radarsat 2 imagery with a resolution span of 1 100 m landsat8 imagery is also used to identify the orientation and spacing of leads the study period centers around three large wave events during august september 2014 identified by swift buoys and wavewatch iii model data the range of floe sizes from different resolutions provides the overall distribution across a wide range of ice properties and estimated thickness all cumulative floe size distribution curves show a gradual bending toward shallower slopes for smaller floe sizes the overall slopes in the cumulative floe size distribution curves from landsat8 images are lower than while those from radarsat 2 are similar to previously reported results in the same region and seasonal period the medea floe size distributions appeared to be sensitive to the passage of storms lead orientations regardless of length correlate slightly better with the peak wave direction than with the mean wave direction their correlation with the geostrophic wind is stronger than with the surface wind the spacing between shorter leads correlates well with the local incoming surface wavelengths obtained from the model peak wave frequency the information derived shows promise for a coordinated multisensor study of storm effects in the arctic marginal ice zone

ancient wet aeolian environments on earth clues to presence of fossil live microorganisms on mars abstract ancient wet aeolian wet sabkha environments on earth represented in the entrada and navajo sandstones of utah contain pipe structures considered to be the product of gas water release under pressure the sediments originally had considerable porosity allowing the ingress of living plant structures microorganisms clay minerals and fine grained primary minerals of silt and sand size from the surface downward in the sedimentary column host rock material is of a similar size and porosity and presumably the downward migration of fine grained material would have been possible prior to lithogenesis and final cementation recent field emission scanning electron microscopy fesem and eds energy dispersive spectrometry examination of sands from fluidized pipes in the early jurassic navajo sandstone reveal the presence of fossil forms resembling fungal filaments some bearing hyphopodium like structures similar to those produced by modern tropical leaf parasites the tropical origin of the fungi is consistent with the paleogeography of the sandstone which was deposited in a tropical arid environment these fossil fungi are silicized with minor amounts of caco 3 and fe and in some cases a si al ratio similar to smectite they exist as pseudomorphs totally depleted in nitrogen adhering to the surfaces of fine grained sands principally quartz and orthoclase similar wet aeolian paleoenvironments are suspected for mars especially following catastrophic sediment charged floods of enormous magnitudes that are believed to have contributed to rapid formation of large water bodies in the northern plains ranging from lakes to oceans these events are suspected to have contributed to a high frequency of constructional landforms also known as pseudocraters related to trapped volatiles and water enriched sediment underneath a thick blanket of materials that were subsequently released to the martian surface forming piping structures at the near surface and constructional landforms at the surface this constructional process on mars may help unravel the complex history of some of the piping structures observed on earth on earth evidence for the constructional landforms has been all but erased and the near surface piping structures exposed through millions of years of differential erosion and topographic inversion now occur as high standing promontories if the features on both earth and mars formed by similar processes especially involving water and other volatiles and since the piping structures of earth provided suitable environments for life to thrive in the martian features in the northern plains should be considered as prime targets for physico mineral chemical microbiological analyses once the astrobiological exploration of the red planet begins in earnest

wave propagation in the marginal ice zone model predictions and comparisons with buoy and synthetic aperture radar data in this paper the ocean wave dispersion relation and viscous attenuation by a sea ice cover are studied for waves propagating into the marginal ice zone miz the derivation of the dispersion relation and the viscous attenuation by an ice sheet are discussed for waves under flexure and pack compression in the miz the flexure effect is important for short waves for a fixed wave period the changes in wavelength and group velocity as a function of ice thickness are significant in turn the exponential wave attenuation rate shows a rollover at short wave periods whereby the rapid increase in wave attenuation rate with decreasing wave period slows down or even turns into a decrease the labrador ice margin experiment limex conducted on the miz off the east coast of newfoundland canada in march 1987 provides us with aircraft synthetic aperture radar sar imagery wave buoy and ice property data on the basis of the wave number spectrum from the sar data and the concurrent wave frequency spectrum from the ocean buoy data and accelerometer data on the ice during limex 87 the dispersion relation has been estimated and compared with a model wave energy attenuation rates are estimated from sar data and the ice motion package data which were deployed at the ice edge and into the ice pack and compared with the model the model data comparisons are reasonably good for the ice conditions observed during limex 87 some previously reported data of wave attenuation in the miz are revisited for model comparison

digital image processing of airborne geophysical data for uranium mineralized breccia pipes exploration in northwestern arizona digital image processing and integration of data sets have been used to develop exploration models from airborne electromagnetics em magnetics and very low frequency electromagnetics vlf em data collected over an area in northwestern arizona the area has potential for the occurrence of uranium mineralized breccia pipes apparent resistivity and overburden thickness were derived from the em measurements using half space models digital image processing techniques applied to the geophysical data sets included 1 conversion of the data into gridded scale images 2 spatial filtering for noise removal 3 integration and analysis of the data sets and 4 modeling using various parameter combinations the general relationships between the geophysical variables parameters and their ability to detect metallic deposits were used as guides in selecting digital number ranges that were used as input into various models one of the best models incorporated apparent resistivity and total field magnetics t

investigation of late holocene moraines in the western southern alps new zealand applying schmidt hammer exposure age dating chronological studies applying schmidt hammer exposure age dating shd were performed on six glacier forelands in the western part of the southern alps new zealand although lithological heterogeneity prevented a regional age calibration curve to be established local age calibration curves for la perouse glacier and strauchon glacier could be derived they show similar linear equations and trends slopes and enabled a preliminary assessment of the representativeness of individual 10be terrestrial cosmogenic nuclide dating tcnd ages obtained from the other forelands no mid and early holocene advance periods were detected clusters of moraine ages date around 2800 1850 1450 and 1100 900 years ago followed by the little ice age commencing c 500 years ago there is no good agreement with earlier radiocarbon based studies and recently published tcnd chronologies as it will be outlined this partly could be the result of different approaches to the palaeoclimatic interpretation of the dated samples

clastic pipes and soft sediment deformation of the jurassic carmel formation southern utah u s a implications for pipe formation mechanisms and host rock controls abstract vertically oriented columns of sandstone termed clastic pipes are common in jurassic deposits of the colorado plateau exposures in the sabkha to fluvial strata of the carmel formation in southern utah provide an excellent opportunity to understand pipe formation mechanisms and controls on their expressions these clastic pipes demonstrate significant variability and fall into two major categories 1 primary textural pipes and 2 non textural pipes primary textural pipes show significant textural differences relative to the host rock including an internal outward grain coarsening indicative of traction structures the pipes contain entrained brecciated host material and the surrounding host rock has associated soft sediment deformation primary textural pipes formed through multiple liquefaction and fluidization events as evident from crosscutting pipes multiple eruption horizons traction structures and other evidence of fluid suspended sediment transport non textural pipes do not have significant textural differences from the surrounding host rock but have clear diagenetic differences e g mineral coloration and cement differences relative to the host rock these non textural pipes formed through the upward expulsion of fluids similar to primary textural pipes but the fluid forces were likely insufficient to fully fluidize the sand overall the porous sandstone host rock plays a key role in explaining pipe characteristics including their cylindrical geometry versus tabular geometries in mudstones and diagenetic expression pipe variability typically corresponds to lithologic and stratigraphic changes in the surrounding host rock these pipe examples are key paleoenvironmental indicators which give valuable information about subsurface fluids and the presence of a near surface groundwater system

finite floe wave reflection and transmission coefficients from a semi infinite model a model to describe the reflection and transmission of ocean waves by a single ice floe is developed from the semi infinite model of fox and squire 1990 1991 this is done by considering the coefficients for the transition from ice to water in the semi infinite case in terms of those from water to ice finite floe reflection and transmission coefficients r and t respectively are then found as the solution of a set of four simple simultaneous equations the properties of r and t are investigated and examples of their absolute values are given for several geometries r compares well with the predictions of a precise model in the case of deep water these results suggest that the analytical model described has applications to defining the sea state within marginal ice zones given the floe size and ice thickness distributions and the incoming sea wave spectrum

observation of wave refraction at an ice edge by synthetic aperture radar in this note the refraction of waves at the ice edge is studied by using aircraft synthetic aperture radar sar penetration of a dominant swell from open ocean into the ice cover was observed by sar during the labrador ice margin experiment limex conducted on the marginal ice zone miz off the east coast of newfoundland canada in march 1987 at an ice edge with a large curvature the dominant swell component disappeared locally in the sar imagery six subscenes of waves in the miz from the sar image have been processed revealing total reflection refraction and energy reduction of the ocean waves by the ice cover the observed variations of wave spectra from sar near the ice edge are consistent with the model prediction of wave refraction at the ice edge due to the change of wave dispersion relation in ice developed by liu and mollo christensen 1988

the saqisan mine a paleokarst uranium deposit south china abstract the saqisan uranium deposit located in guangxi province south china is hosted mainly by a dark gray limestone solution breccia unit and paleocavern fill sedimentary rocks the deposit is the largest known breccia hosted uranium deposit in china and was initially described as of synsedimentary shallow marine origin however recent open pit operations at the saqisan mine have uncovered new exposures that necessitate a thorough change in the genetic interpretation of the deposit the new exposures suggest that the occurrence of saqisan ores in sediment filled solution breccia and paleokarst cavities of limestone is in part similar to that of solution collapse breccia pipe type uranium deposits in arizona united states the interconnected paleokarst passages and caverns were filled with consolidated mineralized clastic sedimentary rocks most of the orebodies were deposited in the interconnected paleokarst passages and caverns two stages of primary uranium mineralization are recognized the early stage i mineralization is the most important for uranium as it accounts for 60 of saqisan s total uranium tonnage stage i mineralization formed low grade ore the late stage ii mineralization which accounts for the remaining 40 of saqisan s total uranium tonnage is hosted by strongly silicified foliated and mylonitized host limestones the uranium in stage i ores predominantly occurs as micro sized pitchblende in the clay rich breccia matrix the uranium in stage ii ores mainly occurs as pitchblende veinlets 0 1 2 mm wide and as disseminated pitchblende grains ranging from less than 0 1 to 1 mm in size sulfur isotope data indicate that biogenic pyrite in the host carbonate may have been the major source of sulfur in the mineralizing fluids oxygen and carbon isotope data show that most of the participated co 2 and hco 3 during stage i mineralization was derived from bicarbonate dissolved out of the marine host carbonate oxygen and hydrogen isotope data combined with determinations of temperature and salinity for the inclusion fluids of stage ii veinlet quartz show that the ore bearing fluids of stage ii mineralization are apparently devoid of co 2 and ch 4 and were originally saline meteoric ground water these basinal brines which were from connate waters trapped in the paleozoic carbonates are believed to have flowed along aquifers of the basinal sequence and up preexisting subvertical faults to produce the observed style of mineralization by chemical interaction with host carbonates it is postulated that the high grade uranium ore of stage ii is the product of multiple superimposed reconcentration of uranium from the early synpaleokarstic ore stage i by low to middle temperature 110 251 c uranium enriched hydrothermal brines driven by a regional heating event such as the late yanshanian tectonism the heat source for the saqisan hydrothermal system could have been related to conversion of mechanical energy into heat during the late yanshanian regional tectonic deformation

uranium deposits of franceville basin gabon role of organic matter and oil cracking on uranium mineralization abstract the lower proterozoic uranium deposits in the franceville basin gabon are mainly known to have hosted natural nuclear reactors however this basin also witnessed a former petroleum system which shows major occurrences of uranium ores associated with organic matter the uranium mineralization is the result of several episodes of oil generation and migration fluid mixing and hydrofracturing during burial at around 2 0 ga black shales were heated and expelled hydrocarbons which migrated in underlying sandstones the first episode of oil migration was synchronous with a silicification event produced by a hot low salinity fluid as shown by fluid inclusions trapped in quartz overgrowths the second episode was contemporaneous with quartz dissolution and is characterized by the mixing of hydrocarbons and oxidizing u bearing brine which resulted in the precipitation of uo2 inclusions in oil then oil to gas conversion generated overpressured gas trapped in pores with uraniferous bitumen nodules changes in the stress regime probably favored radial hydrofracturing around bitumen nodules and subsequently the development of a pervasive micro fracture network there uo2 precipitated together with cu fe sulfides through thermochemical sulfate reduction favored by the presence of hydrocarbons and methane

rates of holocene chemical weathering little ice age glacial erosion and implications for schmidt hammer dating at a glacier foreland boundary fabergstolsbreen southern norway average rates of holocene chemical weathering and little ice age glacial erosion of bedrock are estimated across the glacier foreland boundary of an outlet glacier of the jostedalsbreen ice cap southern norway estimates are derived from two types of evidence 1 the heights of quartz veins above adjacent surfaces of granitic or granodioritic gneiss and 2 schmidt hammer r values of rock hardness average and maximum rates of surface lowering of gneiss surfaces by chemical weathering are 1 63 and 3 61 mm ka respectively whereas many quartz veins exhibit negligible weathering after c 9700 years little ice age glacial erosion rates are at least two orders of magnitude greater than the chemical weathering rates except in a narrow marginal zone inside but close to the little ice age limit where patches of weathered surface survive bedrock surfaces outside and well inside the little ice age glacier foreland boundary are shown to have potential for improved calibrated age dating using r val

a correlation between schmidt hammer rebound numbers with impact strength index slake durability index and p wave velocity the main objective of this study was to establish statistical relationship between schmidt hammer rebound numbers with impact strength index isi slake durability index sdi and p wave velocity these are important properties to characterize a rock mass and are being widely used in geological and geotechnical engineering due to its importance schmidt hammer rebound number is considered as one of the most important property for the determination of other properties like isi sdi and p wave velocity determination of these properties in the laboratory is time consuming and tedious as well as requiring expertise whereas schmidt hammer rebound number can be easily obtained on site which in addition is non destructive so in this study an attempt has been made to determine these index properties in the laboratory and each index property was correlated with schmidt hammer rebound values empirical equations have been developed to predict isi sdi and p wave velocity using rebound values it was found that schmidt hammer rebound number shows linear relation with isi and sdi whereas exponential relation with p wave velocity to check the sensitivity of empirical relations student s t test was done to verify the correlation between rebound values and other rock index properties

measurements of waves in landfast ice using inertial motion units inertial motion units imus are used to perform measurements of waves in water covered by landfast ice close to the ice edge in svalbard the effective noise level of the instruments is assessed in controlled wave tank experiments a set of measurements collected in tempelfjorden svalbard in march 2015 is presented and the ability of the sensors to operate in the field is validated several characteristics of the recorded signals including correlation between the different sensors are analyzed horizontal and vertical motions are of the same order of magnitude a clear transition in the signal properties is observed in relation with changes in incoming wave field and the development of cracks in the ice layer we show that complex physics takes place when waves propagate in landfast ice and that the use of times series containing information on the full three dimensional linear acceleration rather than spectra is required to capture the underlying phenomena

a continent wide study of australia s uranium potential part i gis assisted manual prospectivity analysis abstract this paper describes the approach to and outcomes of a manual analysis i e a cognitive assessment of spatial and non spatial data of the uranium potential of 90 geological regions in australia for this analysis the 14 principal uranium deposit types recognized by the international atomic energy agency were grouped in six uranium systems models i e surficial sedimentary igneous related metamorphic metasomatic unconformity related and vein related uranium systems on the basis of similar genetic processes environments of ore formation and ingredients mappable at the regional to continent scale the newly proposed uranium systems models are structured according to the mineral systems approach and focus on the critical mineralization processes that must occur for a uranium deposit to form in a particular region our manual prospectivity analysis employed this approach to assess the probability of the critical genetic processes having occurred in each geological region in this semi quantitative probabilistic evaluation technical quality and opportunity ranking schemes were used to rank each geological region based on the probability of occurrence of and potential for high quality uranium deposits and opportunity for securing prospective ground based on this assessment the geological regions with the greatest potential for discovery of potentially recoverable uranium resources are the ashburton broken hill litchfield mcarthur money shoal murphy paterson pine creek and northeast tasmania regions i e quality ranking of 10 0 the gawler and polda regions i e 9 0 and the amadeus georgetown stuart tanami regions i e 8 1 most of these regions contain known unconformity related or sandstone hosted uranium deposits although some of them are pure conceptual plays that have received relatively little attention in terms of uranium exploration maps based on the numerical output of the prospectivity analysis helped to inform area selection decisions and detailed follow up studies and focus time and resources the template developed in this study can easily be modified to suit prospectivity analyses for other metals or a similar investigation in another country as illustrated in part ii the best possible approach to a complex continent wide prospectivity analysis is to harness the strengths of both manual and automated i e sophisticated computational techniques applied to spatial data approaches as these methodologies essentially address each other s limitations

u th ne and multidomain u th he systematics of a hydrothermal hematite from eastern grand canyon a hydrothermal hematite from the redwall limestone in eastern grand canyon arizona usa was analyzed for u th he and u th ne systematics the dense polycrystalline aggregate has u and th concentrations of 16 ppm each neon produced by particle capture on 18 o is abundant in the sample it constitutes 90 of total 21 ne and indicates a u th ne age of 217 5 ma this value provides a lower bound for the formation age of the sample but detailed interpretation is not possible given the current absence of neon diffusion data for hematite the 130 2 ma u th he age is much younger than the ne age and therefore must be a cooling age highly reproducible step heating he release experiments reveal the existence of a spectrum of diffusion domain sizes spanning about 3 orders of magnitude in radius corresponding to he closure temperatures ranging from 0 to 150 c these domains may correspond to crystallites in the specimen which are observed to range from smaller than a few nm to a few m 4he 3he age spectra acquired from the same experiments define a distinctive sigmoidal shape with step ages increasing monotonically from 0 to 210 ma this pattern clearly records the presence of the multiple domains as the hematite acquired its radiogenic helium coupling of the 4he 3he spectra and the diffusion data allow modeling of permissible time temperature paths experienced by the hematite these paths can be compared with independent thermal history reconstructions for eastern grand canyon characterized by 170 m yr of sedimentary burial followed by regional unroofing and canyon incision beginning at 80 ma the unroofing portion of the path inferred from the hematite is in good agreement with apatite u th he and fission track data the results permit rapid cooling in late cretaceous early tertiary time suggest a subsequent period of slow cooling through temperatures of 50 70 c with accelerated cooling ensuing after 20 ma in contrast the hematite data demand temperatures in some part s of the mesozoic that are at least 100 c hotter than expected based on burial depth estimates this may indicate that the sample experienced a reheating event associated with the passage of fluids similar to those observed at nearby mineralized breccia pipes overall these data provide motivation for further work to understand he and ne behavior in hematite and their potential use in thermochronometry

genesis of the sanbaqi deposit a paleokarst hosted uranium deposit in china the sanbaqi uranium deposit in hunan province south china is the largest of a group of paleokarst hosted uranium deposits in lower carboniferous limestone mineralization is localized in cavities and fault breccias formed by dissolution of carbonates four episodes of karst formation are recognized late triassic early jurassic late jurassic early cretaceous cretaceous tertiary and recent field relations indicate that the main uranium mineralization is related to the second karst episode this is supported by isotopic ages of two pitchblende samples at 129 ma and 134 ma as indicated by their nearly concordant data points on concordia plot these ages are in the time range of the early yanshanian tectonic movements that affected southern china and the faulting related to the movements likely triggered the mineralization process at the sanbaqi deposit associated minerals include pyrite millerite ullmannite niccolite molybdenite chalcopyrite sphalerite galena calcite and dolomite fluid inclusion studies on calcite reveal that temperature of ore deposition was from 181 to 150 c the 18o and d values of the ore fluids range from 1 5 to 7 9 per mil and from 30 4 and 54 8 per mil respectively the mineralogical fluid inclusion and isotopic data indicate that the minerlization took place in episodic pulses of hydrothermal fluids that were introduced along a set of ring faults mobilization and redeposition of earlier formed ore minerals in an open system added to the complexity of the paragenetic sequence younger episodes of mineralization occurred during the later karst events as suggested by the geological and additional pitchblende u pb isotopic data during the cretaceous tertiary late yanshanian tectonic movements and recently finally a comparison of the sanbaqi uranium deposit with the uranium deposits hosted by solution collapse breccia pipes of the colorado plateau usa shows that they have many similarities

a theoretical laboratory and field study of ice coupled waves field and laboratory data of ice coupled waves propagating beneath shore fast ice are presented and compared with a theoretical model for sea ice which allows temperature variation although the laboratory data set is essentially qualitative because of scaling problems the measured wave characteristics compare favorably with those seen in the field the theory fits the field data set well both for the dispersive behavior and for the energy decay as the ice coupled waves penetrate the ice sheet moreover a maximum displacement suggested by theory is seen in field data for the first time it is proposed that this peak may be associated with the breakup of shore fast ice in exposed regions the theoretical treatment presented assumes sea ice to be thermorheologically simple an untested hypothesis which will require later experimental verification however the theory is quite general and can be used to solve a variety of sea ice mechanical problems where creep is considered important but where the loads and displacements are small enough that linearity prevails

spatial attenuation the most sensitive ultrasonic parameter for detecting petrographic features and decay processes in carbonate rocks abstract the evaluation of stone quality by means of non destructive tests is of vital importance especially when rock is used as a building material usually however only vp p wave velocity is considered when rock properties such as strength durability or decay level are assessed in this paper we propose a novel ultrasonic estimator based on wave energy spatial attenuation s the benefits of this estimator were evaluated by comparison with five other ultrasonic parameters compressional v p and shear v s wave velocities velocity ratio v p v s waveform energy and temporal attenuation the sensitivity of each ultrasonic parameter was compared by measuring 300 samples from ten different types of rock each type was selected according to its mineralogy calcite and or dolomite rock and structural complexity homogeneous fractured brecciated foliated or laminated samples were subjected to weathering tests thermal shock and salt crystallisation tests in order to study the sensitivity of both ultrasonic parameters during fracture initiation fracture growth and rock fabric disintegration results show that although vp is the most widely used parameter the information it yields is extremely imprecise however the new parameter s is highly sensitive to the petrographic characteristics of rocks as well as to the presence of individual defects fractures vugs or disintegrated areas moreover the most significant aspect of s is that its values fall between two fixed limits 0 db cm and 20 db cm a rock with a s value close to 0 db cm is an unweathered homogeneous and good quality rock whilst a s value higher than 12 db cm indicates extreme decay i e open fractures developed vugs and or disintegrated areas

hydrothermal breccia related cumoau mineralization in late precambrian granites western cape province south africa abstract hydrothermal breccia bodies with cu mo au mineralization are present in a leucogranite related to the precambrian cape granite suite the host rock is typical of anorogenic a type associations ranging in composition from quartz syenite to alkaligranite the quartz syenites contain na ca amphiboles and range from amphibole to biotite amphibole and leucoratic syenites a major hydrothermal event affecting the alkaligranite took place at 450 c co 2 overpressure caused the first brecciation event the breccias are present in the alkaligranite and on the contact of alkaligranite and quartz syenites at least three stages of brecciation are recognizable the latter stage typical of low temperature epithermal conditions and siderite enrichment cu mineralization is restricted mainly to the breccias and highest values are obtained in sheeting zones bordering the intensely brecciated areas au and mo mineralization is erratic and although the breccias are generally enriched in these two elements high values are typically found in alkaligranite not affected by brecciation

the schmidt hammer in rock material characterization the schmidt hammer provides a quick and inexpensive measure of surface hardness that is widely used for estimating the mechanical properties of rock material however a number of issues such as hammer type normalization of rebound values specimen dimensions surface smoothness weathering and moisture content and testing data reduction and analysis procedures continue to influence the consistency and reliability of the schmidt hammer test results this paper presents a a critical review of these basic issues and b the results of tests conducted on granitic rocks of various weathering grades in the light of the conclusions of this review it was found that a very good correlation exists between l and n hammer rebound values and that both hammers are fairly sensitive to the physical properties particularly to dry density though less so to effective and total porosities the n hammer producing a lesser scatter in the data proved to be more efficient than the l hammer in predicting uniaxial compressive strength and young s modulus the exponential form of the correlation curves was found to reflect microstructural changes during the course of weathering and the differences in the probing scales or mechanisms in the means of measuring these mechanical properties and could be generalized to other crystalline igneous rocks the possibility of predicting weathering grades from rebound values was also explored the changes in the rebound values during multiple impacts at a given point produced a better indication of the weathering grade than a single impact value it was concluded that increasing the impact energy and plunger tip diameter should significantly reduce the scatter in coarse grained weathered rocks and hence improve the reliability of the schmidt hammer as a rock material characterization tool

geochemical soil sampling for deeply buried mineralized breccia pipes northwestern arizona abstract thousands of solution collapse breccia pipes crop out in the canyons and on the plateaus of northwestern arizona some host high grade uranium deposits the mineralized pipes are enriched in ag as ba co cu mo ni pb sb se v and zn these breccia pipes formed as sedimentary strata collapsed into solution caverns within the underlying mississippian redwall limestone a typical pipe is approximately 100 m 300 ft in diameter and extends upward from the redwall limestone as much as 1000 m 3000 ft unmineralized gypsum and limestone collapses rooted in the lower permian kaibab limestone or toroweap formation also occur throughout this area hence development of geochemical tools that can distinguish these unmineralized collapse structures as well as unmineralized breccia pipes from mineralized breccia pipes could significantly reduce drilling costs for these orebodies commonly buried 300 360 m 1000 1200 ft below the plateau surface design and interpretation of soil sampling surveys over breccia pipes are plagued with several complications 1 the plateau capping kaibab limestone and moenkopi formation are made up of diverse lithologies thus because different breccia pipes are capped by different lithologies each pipe needs to be treated as a separate geochemical survey with its own background samples 2 ascertaining true background is difficult because of uncertainties in locations of poorly exposed collapse cones and ring fracture zones that surround the pipes soil geochemical surveys were completed on 50 collapse structures three of which are known mineralized breccia pipes each collapse structure was treated as an independent geochemical survey geochemical data from each collapse feature were plotted on single element geochemical maps and processed by multivariate factor analysis to contrast the results between geochemical surveys collapse structures a means of quantifying the anomalousness of elements at each site was developed this degree of anomalousness named the correlation value was used to rank collapse features by their potential to overlie a deeply buried mineralized breccia pipe soil geochemical results from the three mineralized breccia pipes the only three of the 50 that had previously been drilled show that 1 soils above the sbf pipe contain significant enrichment of ag al as ba ga k la mo nd ni pb sc th u and zn and depletion in ca mg and sr in contrast to soils outside the topographic and structural rim 2 soils over the inner treeless zone of the canyon pipe show mo and pb enrichment anf as and ga depletion in contrast to soils from the surrounding forest and 3 the soil survey of the mohawk canyon pipe was a failure because of the rocky terrane and lack of a b soil horizon or because the pipe plunges at least 11 of the 47 other collapse structures studied contain anomalous soil enrichments similar to the sbf uranium ore bearing pipe and thus have good potential as exploration targets for uranium one of these 11 1102 does contain surface mineralized rock these surveys suggest that soil geochemical sampling is a useful tool for the recognition of many collapse structures with underlying ore bearing breccia pipes

gravity waves propagating into an ice covered ocean a viscoelastic model 1 a viscoelastic model is proposed to describe the propagation of gravity waves into various types of ice cover the ice ocean system is modeled as a homogeneous viscoelastic fluid overlying an inviscid layer both layers have finite thickness the viscosity is imagined to originate from the frazil ice or ice floes much smaller than the wavelength and the elasticity from ice floes which are relatively large compared to the wavelength a compact form of the dispersion relation is obtained under proper limiting conditions this dispersion relation can be reduced to several previously established models including the mass loading model the viscous layer model and the thin elastic plate model the full dispersion relation contains several propagating wave modes under the ice cover the following two criteria are used to select the dominant wave mode 1 wave number is the closest to the open water value and 2 attenuation rate is the least among all modes the modes selected from those criteria coincide with the ones discussed in previous studies which are shown to be limiting cases in small or large elasticity regimes of the present model in the intermediate elasticity regime however it appears that there are three wave modes with similar wavelengths and attenuation rates implications of this intermediate elasticity range remain to be seen the general viscoelastic model bridges the gap among existing models it also provides a unified tool for wave ice modelers to parameterize the polar regions populated with various types of ice cover

the schmidt hammer as a relative age dating tool and its potential for calibrated age dating in holocene glaciated environments the schmidt hammer is a relatively cheap portable sturdy instrument with proven value over the last two decades or so in rapidly dating coarse inorganic deposits of diverse origins early views were that its dating role was limited to distinguishing recently exposed from much older typically either a few sites of possibly different ages or occasional older surfaces amongst many young sites were studied more recently calibration curves based on individual r value means from small numbers 2 4 of sites of known ages have been used to estimate the ages of undated sites we present schmidt hammer rebound r values from 28 little ice age and younger 23 preboreal and 7 younger dryas glaciated surfaces in southern norway in order first to test rigorously the robustness of the instrument as a relative age dating tool despite being obtained from different surfaces moraines glaciofluvial deposits and bedrock and varied metamorphic lithologies the r value overall means and 95 confidence intervals for the little ice age preboreal and younger dryas age categories respectively 60 0 1 6 41 6 1 4 and 34 2 2 0 are statistically significantly different only two outlying sites in the two younger age categories have overlapping confidence intervals demonstrating remarkable robustness in differentiating early and late holocene surfaces the distinction between preboreal and younger dryas sites with terminal dates 2000 years apart is less clear but still statistically significant though possibly partly because of enhanced weathering conditions at the predominantly well vegetated younger dryas sites second we examine the feasibility and desirability of controlling non age related factors including some previously considered critical instrument wear operator bias initial rock surface texture which emerge either as less important than previously argued or as relatively unimportant together with others previously unreported e g long term changes in lichen soil snow and vegetation covers third we investigate the potential for calibrated age dating by applying exploratory linear rates of r value decline to selected combinations of sites the results suggest that error limits of ca 700 to 1600 years should be achievable over the holocene timescale this improved dating capability however will require adequate numbers of site means not only for each age category used to define these curves but also for each set of test surfaces of the same ages recommendations are made for a suitable sampling protocol for developing further the schmidt hammer as a calibrated age dating tool

reflection and transmission characteristics at the edge of shore fast sea ice the reflection and transmission of ocean waves at a sea ice boundary is reconsidered the sea ice is modelled as a continuous thin elastic plate of uniform thickness floating on water of arbitrary constant depth unlike earlier solutions matching of potentials between the free surface domain and the ice covered domain is done at all depths previous solutions were incompletely matched as the potentials in each domain were deficient in the present solution a number of the infinity of evanescent modes which were hitherto ignored are included in the solution and allow matching to be carried out by minimization of an integrated error term from surface to seafloor reflection and transmission are found to be markedly influenced by the inclusion of these modes suggesting that conclusions based on the incomplete potentials may be substantially in error

isrm suggested method for determination of the schmidt hammer rebound hardness revised version with its portable simple and affordable attributes the schmidt hammer sh is an ideal index apparatus which underlies its increasing popularity and expanding range of applications the sh rebound hardness value r is perhaps the most frequently used index in rock mechanics practice for estimating the uniaxial compressive strength ucs and the modulus of elasticity e of intact rock both in laboratory conditions and in situ the sh is also widely used for estimating the ucs of discontinuity walls and assessing the workability excavatability and boreability of rocks by mechanical means cutting polishing milling crushing and fragmentation processes in quarrying drilling and tunneling

new approaches to the characterization of clay bearing densely jointed and weak rock masses various classification systems for rock masses have been used in engineering applications however these systems are not sufficient to classify clay bearing densely jointed and weak rock masses among the factors that cause this deficiency are the damaging effect of water on rocks which has not sufficiently been described in the existing classification systems this factor was allowed for by the inclusion of new parameters in the modified rock mass classification m rmr system developed in recent years the aim of this study is to make contributions to the m rmr classification system and to overcome the difficulties encountered in the classification procedure for this purpose data were collected for rock mass classification from 13 clay bearing densely jointed and weak rock masses in four regions yatagan soma baskoyak and guvenc located in the western and middle parts of turkey the discontinuity data were collected by the line survey technique and evaluated by statistical methods in addition to the uniaxial compressive strength test for the determination of the rating for intact rock strength the block punch index test was also considered as an alternative parameter and the slake durability index test and x ray diffraction analyses were performed on 104 samples collected from the studied rock masses further the weathering coefficient wc determined by schmidt hammer was considered as an alternative parameter for the determination of the rating for joint weathering as a result of statistical evaluation of data obtained from the field and laboratory studies it has been concluded that the block punch index bpi could be used as an alternative parameter for the determination of the rating for intact rock strength in the m rmr classification system it was also found that the slake durability index id determined at the fourth cycle would be a more effective approach than the second cycle index that has previously been used to express the unfavourable effect of water on the rock mass the propositions made in the present work to contribute to the m rmr system were tested in back analyses of three previously failed slopes and the performance of the system with the newly introduced improvements appeared to be satisfactory

fluid inclusions related to uranium deposits a review fluid inclusions have been observed and studied in rocks of most types of uranium deposits except surflcial ones such as calcretes and the roll type in sandstone temperatures of formation range up to nearly 400 c but most deposits were formed at more moderate temperatures of 90 250 c it is evident from the relatively small number of studies however that the ore forming process occurred at deeper levels than previously thought the chemistry of the fluids ranges from nearly pure water to very dense brines and co 2 is a common component in some cases gas analyses allow determination of f o 2 of the fluid a key parameter for uranium transport and deposition

seismogenically induced fluidization of jurassic erg sands south central utah large bodies of fluidized sandstone occur in the jurassic entrada carmel page and navajo formations at several locations in south central utah they are most abundant in the entrada sandstone where they commonly occur in clusters have a cylindrical form and have a sharp contact with their cross bedded host rock these clastic pipes are as wide as 75 m and have exposed heights of as much as 100 m some of the entrada pipes extend well into the underlying carmel redbeds other clastic pipes in the entrada sandstone are less deformed and display various degrees of brittle to hydroplastic deformation and liquefaction clastic pipes in the page and navajo sandstones are less common but are similar in size and form to those in the entrada and carmel and probably have a similar origin some massive sandstone bodies are irregular in form and have tongue like projections into the host rock implying forcible injection of fluidized sand several pipe host contacts in the entrada sandstone display small scale ring faults where relative displacement can be clearly demonstrated pipe sandstones are invariably down faulted locally as much as 5 m at two sites carmel host rock is upwarped around the entrada pipes stratified and cross bedded breccia blocks occur in many entrada pipes and preliminary petrographic analysis indicates that at least some of these breccia blocks are derived from the host rock homogeneous pipe sandstones are also petrographically similar to their entrada host rock suggesting that some pipes originate through fluidization of the fine grained entrada fluidization of the entrada must have occurred in a water saturated environment during early diagenesis but before complete lithification most probably under considerable porewater pressure although there are no known modern analogues to these huge masses of structureless sandstone they may have a small scale modern counterpart in earthquake induced sandblows these features were most probably caused by large magnitude seismic events during the middle jurassic although other possibilities cannot be ruled out at this point

strain in shore fast ice due to incoming ocean waves and swell using a development from the theoretical model presented by fox and squire 1990 this paper investigates the strain field generated in shore fast ice by normally incident ocean waves and swell after a brief description of the model and its convergence normalized absolute strain relative to a 1 m incident wave is found as a function of distance from the ice edge for various wave periods ice thicknesses and water depths the squared transfer function giving the relative ability of incident waves of different periods to generate strain in the ice is calculated and its consequences are discussed the ice is then forced with a pierson moskowitz spectrum and the consequent strain spectra are plotted as a function of penetration into the ice sheet finally rms strain computed as the incoherent sum of the strains resulting from energy in the open water spectrum is found the results have implications to the breakup of shore fast ice and hence to the floe size distribution of the marginal ice zone

grain coatings diagenesis of jurassic sandstones in south central utah and implications for targeting fossil microbes on mars abstract clusters of large scale decameters to 100 m dia fluidization pipes have been identified at several locations in jurassic navajo and entrada sandstones in south central utah these typically cut the cross bedded aeolian sabhka host rock at right angles similar pipe like structures have been tentatively identified on mars and the question of the diagenesis of host rock has important implications for the genesis of pipe structures current thinking regarding the genesis of host rock structures is that the grains were derived from wet aeolian sabkha environments eds of all samples indicates a si al ratio of 2 1 suggesting smectite clay minerals are to be expected in a dry mid latitude climatic zone and unlike the pipe structures which contain hyphopodium like structures fungal filaments similar in morphology to modern tropical leaf parasites the host rock is relatively bereft of microbes entombed in grain coatings moreover microtextural data from host rock grains in these wet aeolian wet sabkha environments suggest a lack of volatility judging from infrequent observation of percussion crack evidence of grain collision presumably during the time of formation a microfeature commonly found within the pipe structures the diagenesis process can be reconstructed from the composition of the coatings on recovered grains of quartz feldspar mica and occasional calcite as imaged with the sem and studied by eds xrd of the coatings provides confirmation of the clay mineralogy and inaa is used to cross check the chemistry obtained by eds if similar microfeatures exist on grains from both earth and mars materials transported by similar aeolian processes one would not expect to find fossil evidence of life on grains in host rocks while martian pipe structures may be the optimum target for the astrobiological exploration of the red planet host rock might be relatively devoid of fossil microbes if diagenesis of sandstones on mars is anything like earth

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

relative surface age dating of rock glacier systems near holar in hjaltadalur northern iceland schmidt hammer rebound values and photogrammetric measurements of surface displacement were used to date two active polymorphic high altitude and two relict monomorphic low altitude rock glaciers near holar in hjaltadalur trollaskagi peninsula northern iceland 65 40 n 19 00 w both low altitude rock glaciers are of late weichselian or preboreal origin ca 10 3 9 2 k yr bp with minor later reshaping until the early neoglacial period vatnsdalur i ca 5 2 k yr bp both high altitude rock glaciers consist of an upper lobe overriding a lower lobe corresponding to initiation during different cool phases the initiation of the lower lobes can possibly be attributed to the gh 8 2 event 8 6 8 0 k cal yr bp they reached their terminal position at the end of the vatnsdalur i stage the upper lobes of the high altitude rock glaciers were initiated sometimes between the vatnsdalur i but substantially before the vatnsdalur ii ca 3 0 3 2 k yr bp stages and underwent modification during each following holocene glacier expansion episode culminating the last time in the little ice age thus it is suggested that similar looking rock glaciers occurring elsewhere in the trollaskagi peninsula may have a similar complex history therefore they may not be seen as rather simple landforms developed during the little ice age copyright 2007 john wiley sons ltd

karst hydrology of grand canyon arizona usa summary caves in grand canyon arizona usa fall into two main categories those formed under unconfined conditions and those formed under confined conditions this study focuses on the hydrology and paleohydrology of the confined caves in the redwall muav aquifer where the aquifer is overlain by rocks of the supai group and underlain by the bright angel shale unconfined caves are discussed only in their relation to confined caves discharge for confined groundwater was as it is today primarily from the redwall limestone where it has been incised by the main canyon or its tributaries and where it has converged along a structural low or fault descent of the potentiometric surface or water table over time is recorded by one ore episode and six cave episodes 1 emplacement of cu u ore 2 precipitation of iron oxide in cavities 3 dissolution of cave passages 4 precipitation of calcite spar linings over cave passage walls 5 precipitation of cave mammillary coatings 6 minor replacement of cave wall and ceiling limestone by gypsum and 7 deposition of subaerial speleothems the mammillary episode records the approximate position of the water table when the incision of the canyon was at that level discharge toward spring points has reorganized and adjusted with respect to ongoing canyon and side canyon incision the dissolution of grand canyon confined caves was the result of the mixing of epigene waters with hypogene waters so that undersaturation with respect to calcite was achieved the karst hydrology of grand canyon may be unique compared to other hypogene cave areas of the world

clastic pipes and mud volcanism across mars terrestrial analog evidence of past martian groundwater and subsurface fluid mobilization abstract clastic pipes are cylindrical injection features that vertically crosscut bedding with sharp contacts terrestrial pipes have cylindrical morphologies massive or radially graded interiors and raised outer rims increased grain size and subsequent cementation along the more porous edges makes the rims more resistant to weathering pipes have crosscutting relationships with other pipes due to multiple formation events or migrating eruption centers and are associated with other soft sediment deformation features terrestrial clastic pipes form via liquefaction and fluidization which require a near surface groundwater system to initiate i e sand sized sediments must be saturated for pipes to form clastic pipes cm to 1000 m diameters occur on mars across multiple time periods and terrains and are recognized in both rover and orbital imagery a conical or cylindrical geometry and massive interior core characterize these features the pipes on mars show various geomorphic expressions and are classified into five types by the presence or absence of a raised outer rim or a central pit these types are interpreted to represent the erosional evolution of pipes at different stages from their initial surface eruptive structures to their weathered remnants eroded conical hills martian pipes formed via fluidization as evidenced by 1 raised outer rims possibly indicating textural differences along the pipe edges from traction interactions of fluid suspended sediment 2 crosscutting relationships with other pipes suggesting reactivated fluidization pathways or migrating eruptive vents and 3 close spatial association between pipes and other features thought to form by soft sediment deformation e g contorted bedding integration of terrestrial analog data with the mars observations provides evidence for past martian groundwater and subsurface fluid mobilization

dynamic in situ measurement of sea ice characteristic length we present a method for measuring the characteristic length of sea ice based on fitting to a the recentlyfound solution for the flexural response of a floating ice sheet subject to localized periodic loading unlike previous techniques the method enables localized measurements at single frequencies of geophysical interest and since the measurements may be synchronously demodulated gives excellent rejection of unwanted measurement signal e g from ocean swell the loading mechanism is described and we discuss how the effective characteristic length may be determined using a range of localized measurements the method is used to detemine the characteristic length of the sea ice in mcmurdo sound antarctica

response of a floating sea ice sheet to a steadily moving load an extended analysis of previous experimental work takizawa 1985 is made using the dispersion relation for flexural free waves in a floating ice sheet a diagram that predicts the critical speed at which the ice deflection is amplified markedly is presented an understanding of the group velocity provides one explanation for the question why two waves appear in front of and at the rear of the load the two dimensional deflection patterns obtained in the experiment are compared with the existing theoretical results at high speeds the ice beneath the load is found not to be depressed but somewhat elevated it is shown that viscous damping has substantial effects on the ice deflection profile the wave number curves which give the two dimensional wave patterns are also examined and the results verify that a one dimensional model quite adequately describes the wave characteristics in takizawa s experiment

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

the effect of rock moisture on schmidt hammer rebound tests on rock samples from marion island and south africa in an assessment of the influence of internal rock moisture content on schmidt hammer readings rebound r values are found to decrease with increasing moisture content for samples of basalt sandstone and dolerite the maximum decrease in r values is found between oven dry values and saturated rock rebound values the magnitude of which varies from 2 to 10 points on the r scale a quartzite block has the greatest decline of 6 points at 60 per cent saturation for certain rock types under differing site to site field moisture conditions the moisture effect can be a significant factor in the interpretation of the relative state of weathering from rebound values copyright 2002 john wiley sons ltd

multiscale structural and lithologic controls in the development of stream potholes on granite bedrock rivers abstract jointing veins dikes and fracture patterns influence the genesis of potholes in bedrock rivers we use measures of surface rock strength schmidt hammer readings joint orientation and spacing and subsurface rock properties ultrasound velocity to analyze the spatial relationship between joints and potholes in three rivers of the spanish central system the tietar manzanares and alberche rivers at each site we measured the dimensions of between 45 and 77 potholes at least 50 randomly located schmidt hammer rebound values as well as schmidt hammer values in a 15 15 cm grid around each pothole and ultrasonic p wave velocities measured in a 15 15 cm grid around a subset of 12 of the potholes results support our hypotheses that most potholes correlate with joints 89 of potholes are related to joint sets potholes exhibit preferred orientations associated with dominant joints and pothole genesis correlates more strongly with variations in substrate resistance than with hydraulics we classify potholes by morphology and present a genetic sequence for specific morphologies in relation to substrate characteristics

the schmidt hammer as a holocene calibrated age dating technique testing the form of the r value age relationship and defining the predicted age errors most recent developments of schmidt hammer exposure age dating shd as a calibrated age dating tool have been limited by the use of locations at two age control points this has necessitated 1 making assumptions about a linear r value age relationship and 2 basing predictions of age errors only on r value variance at the two age control points this paper analyses 9900 r values obtained from multiple age control points on a sequence of glacio isostatically raised shorelines with well constrained ages skuleskogen high coast world heritage site and environs gulf of bothnia northern sweden ranging from modern to 10 5 ka in age the sampling design involved 30 measurements on granite beach boulders from 30 sites at 11 age control points the r value age relationship is best described by a linear function ordinary least squares ols with an r 2 of 0 89 p 0 0001 predicted age errors are calculated using two approaches 1 ols regression which takes account of the uncertainties associated with the regression line and the age control points and 2 weighted total least squares wtls regression which in addition takes account of possible shoreline age errors and the heteroscedasticity of r value residuals with increasing age with both approaches 95 predicted age errors are relatively modest 355 455 years and 300 515 years respectively with larger r value variance and hence uncertainty for older surfaces and the possibility of further improvement from a more selective field sampling scheme that differentiates between age related and non age related rock surface variability our results also indicate that for certain lithologies and weathering environments it is possible to construct reliable calibrated age curves from relatively few age control points

geochemical exploration for mineralized breccia pipes in northern arizona u s a abstract thousands of solution collapse breccia pipe crop out in the canyons and on the plateaus of northern arizona over 80 of these are known to contain u or cu mineralized rock the high grade u ore associated with potentially economic concentrations of ag pb zn cu co and ni in some of these pipes has continued to stimulate mining and exploration activity in northern arizona despite periods of depressed u prices large expanses of northern arizona are comprised of undissected high plateaus recognition of pipes in these areas is particularly important because mining access to the plateaus is far better than to the canyons the small size of the pipes generally less than 600 ft 200 m in diameter and limited rock outcrop on the plateaus compounds the recognition problem although the breccia pipes which bottom in the mississippian redwall limestone are occasionally exposed on the plateaus as circular features so are unmineralized near surface collapse features that bottom in the permian kaibab and toroweap formations the distinction between these two classes of circular features is critical during exploration for this unique type of u deposit various geochemical and geophysical exploration methods have been tested over these classes of collapse features because of the small size of the deposits and the low level geochemical signatures in the overlying rock that are rarely dispersed for distances in excess of several hundred feet most reconnaissance geochemical surveys such as hydrogeochemistry or stream sediment will not delineete mineralized pipes several types of detailed geochemical surveys made over collapse features located through examination of aerial photographs and later field mapping have been successful at delineating collapse features from the surrounding host rock 1 rock geochemistry commonly shows low level ag as ba co cu ni pb se and zn anomalies over mineralized breccia pipes 2 soil surveys appear to have the greatest potential for distinguishing mineralized breccia pipes from the surrounding terrane although the soil anomalies are only twice the background concentrations for most anomalous elements traverses made over collapse features show consistent enrichment inside of the feature as compared to outside 3 b cereus surveys over a known mineralized pipe show significantly more anomalous samples collected from within the ring fracture than from outside of the breccia pipe 4 helium soil gas surveys were made over 7 collapse features with discouraging results from 5 of the 7 features geophysical surveys indicate that scaler audio magnetotelluric amt and e field telluric profile data show diagnostic conductivity differences over mineralized pipes as compared to the surrounding terrane these surveys coupled with the geochemical surveys conducted as detailed studies over features mapped by field and aerial photograph examination can be a significant asset in the selection of potential breccia pipes for drilling

wave effects on ocean ice interaction in the marginal ice zone the effects of wave train on ice ocean interaction in the marginal ice zone are studied through numerical modeling a coupled two dimensional ice ocean model has been developed to include wave effects and wind stress for the predictions of ice edge dynamics the sea ice model is coupled to the reduced gravity ocean model through interfacial stresses the main dynamic balance in the ice momentum is between water ice stress wind stress and wave radiation stresses by considering the exchange of momentum between waves and ice pack through radiation stress for decaying waves a parametric study of the effects of wave stress and wind stress on ice edge dynamics has been performed the numerical results show significant effects from wave action the ice edge is sharper and ice edge meanders form in the marginal ice zone owing to forcing by wave action and refraction of swell system after a couple of days upwelling at the ice edge and eddy formation can be enhanced by the nonlinear effects of wave action wave action sharpens the ice edge and can produce ice meandering which enhances local ekman pumping and pycnocline anomalies the resulting ice concentration pycnocline changes and flow velocity field are shown to be consistent with previous observations

a field and laboratory study of wave damping by grease ice in a field and laboratory study we discuss the formation growth and wave absorption properties of grease ice our field observations show that grease ice formation occurs under cold windy conditions in both leads and polynyas in leads grease ice forms in the open water then is herded to the down wind edge of the lead in polynyas a langmuir circulation herds the grease ice into long plumes parallel to the wind in the laboratory we grow grease ice in a wave tank and measure its wave absorption properties for single frequency two dimensional waves on a large scale we find that the thickness of the grease ice which increases away from the paddle is determined by a balance between the wave momentum flux and the free surface tilt on a small scale our photographs show that the crystals which make up the grease ice consist of discs measuring about 1 mm in diameter and 1 10 m thick which at low rates of shear sinter together into larger clumps yielding a viscosity increase to measure this non linear viscosity we study the decay of wave amplitude between two critical distances measured inwards from the leading edge the first occurs when the depth of grease ice exceeds k 1 where k is the wave number the second further distance is a line of transition from liquid to solid behavior which we call the dead zone between these two distances the wave amplitude decays with a linear slope which increases as a 0 k 2 where a0 is the wave amplitude in open water concurrent measurements of ice concentration show that it increases from values of 18 22 at the leading edge to a local maximum of 32 44 at the dead zone while the values at the dead zone increase non linearly with a0k finally comparison of the observed to that calculated from a yield stress viscosity model shows if the yield stress coefficient is proportional to the incident wave momentum flux the model predicts the observed

the metallotectonics in eastern shandong gold metallogenetic province china based on research into the macro and micro structures within the eastern shandong gold metallogenetic province fractures are the main ore controlling and ore bearing structures revealing a process of ductile deformation in the early period and brittle deformation in the later period when gold mineralization mainly occurred the ore bearing structures can be classified into five types a fracture structures b fissure structures c fracture and fissure structures d fracture fissure and concealed explosion breccia pipe structures and e fracture and explosive breccia structures ne trending fractures are the most favourable to the formation of gold orebodies next in importance are the nne trending fractures nw trending fractures controlled the distribution and the maximum depth of gold ore shoots during mineralization and intercept the veins with dextral offsets subsequent to mineralization the different types of orebodies each have their own specific structural controls furthermore the vertical zonation between the auriferous silicified rock and sericite quartz rock is interpreted as resulting from convective circulation the author analyses the areal structural history sets up a structural model and suggests that the difference between the orebodies in the zhaoyuan yexian and mupin rushan metallogenetic areas results from the distinct structural controls on the ore bearing fractures in the two areas

on the oblique reflexion and transmission of ocean waves at shore fast sea ice a mathematical model is reported describing the oblique reflexion and penetration of ocean waves into shore fast sea ice the arbitrary depth model allows all velocity potentials occurring in the open water region to be matched precisely to their counterparts in the ice covered region matching is done using a preconditioned conjugate gradient technique which allows the complete solution to be found to a predefined precision the model enables the reflexion and transmission coefficients at the ice edge to be found and examples are reported for ice plates of different thicknesses a critical angle is predicted beyond which no travelling wave penetrates the ice sheet in this case the deflexion of the ice is due only to evanescent modes critical angle curves are provided for various ice thicknesses on deep intermediate and shallow water the strain field which is set up within the ice sheet due to the incoming waves is also discussed principal strains are provided as are the strains normal to the ice edge finally the spreading function within the ice cover and some consequences of this function to unimodal seas with realistic open water spreading functions are reported with the aim of generalizing the work to model the effect of shore fast ice on an incoming directional wave spectrum of specified structure

field characterisation of weathered ankara andesites abstract this paper presents field and some index properties of weathered ankara andesites carried out over a period of 4 years ankara andesites are distributed widely around the city of ankara on which numerous important structures have been founded thus the weathering characteristics of ankara andesites both from the engineering geological and the rock mechanics points of view are important the field work involved assessment of the rock mass weathering grades conduction of simple field tests schmidt hammer and point load tests on the rock materials characterisation of discontinuities and collection of representative samples from each weathering grade for laboratory testing the relationship between the experimentally determined parameters and quantitative engineering geological descriptions provided a simple geological method for the assessment of the design parameters and mapping the distribution of mass weathering grades as a result of the evaluation an idealized weathering profile and the scale of rock mass weathering grades together with their range of thicknesses were proposed some index tests such as effective porosity schmidt hammer value shv point load strength and seismic velocity provided good relations with the degree of weathering

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

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

schmidt hammer exposure age dating shd of late quaternary fluvial terraces in new zealand schmidt hammer sh r values are reported for surface clasts from numerically dated holocene and pleistocene fluvial terraces in the south island of new zealand the r values are combined with previously obtained weathering rind radiocarbon terrestrial cosmogenic nuclide and luminescence terrace ages to derive sh r value chronofunctions for greywacke clasts from four distinct locations our results show that different weathering rates affect the form of the sh r value versus age curve however a fundamental dependency between the two remains constant over timescales ranging from 102 to 105 years power law scaling constants suggest changes in clast weathering rates are primarily affected by climatic precipitation and temperature and sedimentologic variables source terrane petrology age uncertainties of 22 of the surface age suggest that schmidt hammer exposure age dating shd is a reliable calibrated age dating technique for fluvial terraces copyright 2013 john wiley sons ltd

comparison of electronic and mechanical schmidt hammers in the context of exposure age dating are q and r values interconvertible application of schmidt hammer exposure age dating shd to landforms has substantially increased in recent years the original mechanical schmidt hammer records r rebound values although the newly introduced electronic schmidt hammer silverschmidt facilitates greatly improved data processing it measures surface hardness differently recording q velocity values that are not a priori interconvertible with r values this study is the first to compare the performance of both instruments in the context of field based exposure age dating with a particular focus on the interconvertibility of r values and q values the study was conducted on glacially polished pyroxene granulite gneiss jotunheimen southern norway results indicate that mean q values are consistently 8 10 units higher than mean r values over the range of values normally encountered in the application of shd to glacial and periglacial landforms a convenient conversion factor of 10 units may therefore be appropriate for all but the softest rock types close to the technical resolution of the instruments the electronic schmidt hammer should therefore be regarded as a useful complement and potential replacement for the mechanical schmidt hammer conversion of published r values data to q values requires however careful control and documentation of instrument calibration copyright 2014 john wiley sons ltd

observations of flexural waves on the erebus ice tongue mcmurdo sound antarctica and nearby sea ice abstract new strain data relating to lexural oscillations of the erebus glacier tongue egt mcmurdo sound antarctica are presented and are analysed in the frequency domain the data were collected during november 1989 just 3 months prior to the most recent calving of the ice tongue which occurred in march 1990 a broad band oscillation centred on 50 s is found in both the strain measurements collected on the egt and those collected on the sea ice nearby the oscillation is shown at least in part to be propagating with a phase velocity of approximately 65 m s j in a direction away from the snout towards the grounding line rather than being wholly due to a standing wave pattern in the egt a coupling model between the sea ice and the egt is proposed and is shown to compare reasonably well with the data introduction the erebus glacier tongue egt flows from the western side of mount erebus into mcmurdo sound about 20 km north of new zealand s scott base and the nearby united states base mcmurdo fig 1 its close proximity to excellent logistical support has meant that the egt has been the focus of a number of experimental and theoretical studies to map its geometry and structure holdsworth 1982 and to understand its dynamics holdsworth 1969 1974 goodman and holdsworth 1978 ho1dsworth and ho1dsworth 1978 ho1dsworth and glynn 1981 vinogradov and holdsworth 1985 gui and squire 1989 the egt is known to have calved at least three times since the turn of the cen tury in march 1911 members of scott s british antarctic