the role of magma injection in localizing black smoker activity the mechanisms for localization of black smoker systems at mid ocean ridges remain to be fully understood seismic data for a segment of the juan de fuca ridge with long lived black smoker vents reveal ongoing magma recharge into the crustal magma chamber thereby providing an explanation for the localization

the importance of hydrothermal venting to water column secondary production in the northeast pacific abstract the purpose of this study is to show that seafloor hydrothermal venting in the open northeast pacific ocean has a marked impact on secondary biomass and production within the overlying water column specifically we use net tows and concurrently measured acoustic backscatter data collected over six summers to examine the effects of hydrothermal venting from the endeavour segment of juan de fuca ridge on macro zooplankton biomass and production throughout the entire 2000 m depth range previous research shows that ontogenetic diapausing migrators and their predators from the upper ocean aggregate above the neutrally buoyant plumes in summer and resume feeding on plume and bottom upwelled particles resulting in increased zooplankton reproductive output to the upper ocean within the limitations of our sampling methodology net tows reveal a statistically significant exponential decline in total water column biomass with increasing lateral distance from the vent fields the acoustic backscatter data show a similar decline but only below 800 m depth near surface biomass was highly variable throughout the region but values near vents consistently ranged higher than summer values found elsewhere in the offshore northeast pacific water column biomass was similar in magnitude above and below 800 m depth throughout the region because epiplume biomass can be advected a considerable distance from vent fields biomass enhancement of the water column from hydrothermal venting may extend considerable distances to the west and northwest of the vent sites in the prevailing directions of the subsurface flow based on the extensive acoustic doppler current profiler adcp data collected and the strong correlation between zooplankton production derived from net sample biomass and acoustic backscatter intensity we estimate that daily macro zooplankton production in the upper 400 m of the water column within 10 km of the vent fields averages approximately 16 of photosynthetic primary production the z ratio whereas the total water column zooplankton production averages 26 of surface primary production local grazing rate estimates metabolic constraints and other open ocean studies suggest that the z ratio should be no higher than 5 which it is at off axis background sites in the study region this finding indicates that nutrient sources other than upper ocean primary production fuel both upper and deep ocean zooplankton biomass and growth near the endeavour ridge hydrothermal vents

the cr renazzo type carbonaceous chondrite group and its implications abstract a petrologic geochemical and oxygen isotopic study of eight meteorites identified as cr renazzo type chondrites reveals that they have a set of similar properties that distinguishes them from other chondrite groups and confirms cr as a carbonaceous chondrite group characteristics of the cr group include 1 1 abundant large multilayered fe ni metal rich type i chondrules 2 2 abundant matrix and dark inclusions di that contain microchondrules microfragments and magnetite framboids and platelets 3 3 unique assemblages of serpentine and chlorite rich phyllosilicates and ca carbonates 4 4 ca carbonate rims on chondrules 5 5 abundant fe ni metal with a positive ni vs co trend and a solar ni co ratio 6 6 low abundance of refractory rich inclusions 7 7 amoeboid olivine aggregates aoa with mn rich and mn poor forsterite and 8 8 oxygen isotopic compositions that form a unique mixing line the cr chondrites are breccias consisting of two major components the large layered chondrules and the matrix dark inclusions al rais is an anomalous member in having a higher abundance of the dark inclusion component 70 vol and this accounts for its having a higher volatile content than other members of the group the conditions that prevailed during aqueous alteration of the cr chondrites differed from those of other hydrated chondrite groups and may be the result of a higher temperature environment than that for the ci and cm chondrites the cr chondrite components chondrules matrix dark inclusions etc experienced aqueous alteration to differing degrees prior to assembly of the host chondrites and dark inclusions represent a lithology that was altered by water to a greater degree than the rest of the meteorite the overall degree of hydration in cr chondrites varies among meteorites with al rais being the most hydrated the oxygen isotopic variation of the whole rocks chondrules and matrices may be related to degree of hydration indicating that cr chondrites interacted with a water rich component having heavy oxygen and that was the same as ci and cm water

detailed geomorphology and neotectonics of the endeavour segment juan de fuca ridge new results from seabeam swath mapping a 36 km wide corridor of seabeam bathymetry was collected on the juan de fuca ridge north of 48 00 n in may 1983 these data merged with previous seabeam bathymetric compilations for the cobb offset as well as with sea marc i and sea marc ii side scan sonar seismic reflection magnetometer and deep tow photography data have been used to identify morphological variations along the spreading center of the endeavour segment of the juan de fuca ridge between the cobb offset and sovanco fracture zone the endeavour segment consists of two ridge sections separated by the 13 km wide endeavour offset which formed when spreading jumped from middle valley to west valley 200 000 yr ago the locus of spreading occurs along the entire endeavour segment as a narrow 1 2 km wide shallow 10 30 m deep inner rift which is superimposed upon larger structures that range from broad 5 10 km wide deep as much as 3 000 m median valleys to narrow 5 km wide shallow 2 100 m volcanic ridges an abrupt discontinuity in the tectonic fabric occurs at about 48 05 n south of this latitude spreading occurs within an axial high endeavour ridge which gradually deepens to the south south endeavour valley as it approaches the zone of overlap with the propagating rift at the cobb offset north of 48 05 n the axis is characterized by broad deep median valleys north endeavour valley and west valley these large scale morphological variations reflect a complex interplay of the spreading center with seamount volcanism waning magma supply at the distal ends of ridge axes thermal contrasts across ridge offsets propagating rifts and an unstable triple junction the pronounced axial deep of west valley is interpreted as reflecting the youth of the structure 200 000 yr and may be primarily due to collapse with little extension and magmatism the rift axis jump to west valley fortuitously isolated endeavour seamount the youngest edifice in the heck seamount chain from the pacific plate and trapped it between a pair of overlapping spreading centers at the newly formed endeavour offset development of a remarkably simple overlapping conjugate rift pair at endeavour offset has resulted in spite of the complex and highly variable crustal thickness magma supply and pre existing structural grain rifting in south west valley has caused pre existing topography generated at the endeavour ridge to be destroyed by subsidence and burial thereby creating the apparent discontinuity in morphology north of 48 05 n

tracking fin whale calls offshore the galicia margin north east atlantic ocean data recorded during a temporary deployment of ocean bottom seismometers obss are used in this study to monitor the presence of fin whales around the array in the summer of 2003 ten obss were placed 250 km from the nw coast of iberia in the galicia margin ne atlantic ocean for a period of one month the recorded data set provided a large variety of signals including fin whale vocalizations identified by their specific acoustic signature the use of a dense array of seafloor receivers allowed investigation into the locations and tracks of the signal generating whales using a seismological hypocentral location code individual pulses of different sequences have been chosen to study such tracks problems related to the correct identification of pulses discrimination between direct and multiple arrivals and the presence of more than one individual have been considered prior to location fin calls were concentrated in the last two weeks of the deployment and the locations were spread around the area covered by the array these results illustrate that besides its classical seismological aim deployment of semipermanent seafloor seismic arrays can also provide valuable data for marine mammal behavior studies

formation processes of framboidal pyrite abstract pyrite framboid formation may be the result of four consecutive processes 1 nucleation and growth of initial iron monosulfide microcrystals 2 reaction of the microcrystals to greigite fe 3 s 4 3 aggregation of uniformly sized greigite microcrystals i e framboid growth and 4 replacement of greigite framboids by pyrite the uniform morphology uniform size range and ordering of the microcrystals in individual framboids as well as the range of observed framboid structures from irregular aggregates to densely packed spherical aggregates and polyframboids are consequences of these processes using dlvo theory derjaguin landau verwey and overbeek we have evaluated the stability of colloidal iron monosulfide suspensions with ionic strengths typical of marine and lacustrine waters in addition to van der waals attractive and double layer repulsive forces a term is included to account for the ferrimagnetic properties of greigite numerical models predict that magnetically saturated greigite particles 0 1 m in diameter will rapidly aggregate in either marine or fresh water the aggregation model is in agreement with the sequence of greigite formation followed by pyrite framboid formation established in a previous experimental study sweeney and kaplan 1973 and is consistent with the occurrence of framboids composed of other magnetic minerals e g greigite magnetite and magnesioferrite based on the temperature dependent magnetic properties of greigite and aging experiments in hydrothermal solutions this mechanism for framboid formation via precursor greigite could operate to temperatures of 200 c consistent with the occasional occurrence of pyrite framboids in the paragenesis of metalliferous ore deposits

ranging bowhead whale calls in a shallow water dispersive waveguide this paper presents the performance of three methods for estimating the range of broadband 50 500 hz bowhead whale calls in a nominally 55 m deep waveguide conventional mode filtering cmf synthetic time reversal str and triangulation the first two methods use a linear vertical array to exploit dispersive propagation effects in the underwater sound channel the triangulation technique used here while requiring no knowledge about the propagation environment relies on a distributed array of directional autonomous seafloor acoustics recorders dasars arranged in triangular grid with 7 km spacing this study uses simulations and acoustic data collected in 2010 from coastal waters near kaktovik alaska at that time a 12 element vertical array spanning the bottom 63 of the water column was deployed alongside a distributed array of seven dasars the estimated call location to array ranges determined from cmf and str are compared with dasar triangulation results for 19 whale calls the vertical array ranging results are generally within 10 of the dasar results with the str results providing slightly better agreement the results also indicate that the vertical array can range calls over larger ranges and with greater precision than the particular distributed array discussed here whenever the call locations are beyond the distributed array boundaries

a single station method for the detection classification and location of fin whale calls using ocean bottom seismic stations passive seismic monitoring in the oceans uses long term deployments of ocean bottom seismometers obss an obs usually records the three components of ground motion and pressure typically at 100 hz this makes the obs an ideal tool to investigate fin and blue whales that vocalize at frequencies below 45 hz previous applications of obs data to locate whale calls have relied on single channel analyses that disregard the information that is conveyed by the horizontal seismic channels recently harris matias thomas harwood and geissler j acoust soc am 134 3522 3535 2013 presented a method that used all four channels recorded by one obs to derive the range and azimuth of fin whale calls in this work the detection classification and ranging of calls using this four channel method were further investigated focusing on methods to increase the accuracy of range estimates to direct path arrivals corrections to account for the influences of the sound speed in the water layer and the velocity structure in the top strata of the seabed were considered the single station method discussed here is best implemented when obss have been deployed in deep water on top of seabed strata with low p wave velocity these conditions maximize the ability to detect and estimate ranges to fin whale calls

microseismicity linked to gas migration and leakage on the western svalbard shelf the continental margin off prins karls forland western svalbard is characterized by widespread natural gas seepage into the water column at and upslope of the gas hydrate stability zone we deployed an ocean bottom seismometer integrated into the masox monitoring arctic seafloor ocean exchange automated seabed observatory at the pinch out of this zone at 389 m water depth to investigate passive seismicity over a continuous 297 day period from 13 october 2010 an automated triggering algorithm was applied to detect over 220 000 short duration events sdes defined as having a duration of less than 1 s the analysis reveals two different types of sdes each with a distinctive characteristic seismic signature we infer that the first type consists of vocal signals generated by moving mammals likely finback whales the second type corresponds to signals with a source within a few hundred meters of the seismometer either due east or west that vary on short tens of days and seasonal time scales based on evidence of prevalent seafloor seepage and subseafloor gas accumulations we hypothesize that the second type of sdes is related to subseafloor fluid migration and gas seepage furthermore we postulate that the observed temporal variations in microseismicity are driven by transient fluid release and due to the dynamics of thermally forced seasonal gas hydrate decomposition our analysis presents a novel technique for monitoring the duration intensity and periodicity of fluid migration and seepage at the seabed and can help elucidate the environmental controls on gas hydrate decomposition and release

replacement of pyrite framboids by magnetite in limestone and implications for palaeomagnetism limestones are an important source of palaeomagnetic data with magnetite the dominant carrier of the magnetization because the magnetite is present in low concentrations however it has been directly observed only rarely and in trace amounts in acid treated separates such residues are composed primarily of spheres the ultimate origin of which has been enigmatic7 yet interpretation of the palaeomagnetic data depends on a knowledge of the origin of the magnetite which has been inferred to carry either a chemical or a viscous remanent magnetization here we present electron microscope data obtained from a sequence of samples of onondaga limestone from an east west traverse across northern new york which unambiguously show that magnetite spheres are derived by alteration and replacement of framboidal pyrite remagnetization is thus caused by chemical rather than viscous processes this chemical remanent magnetization is compatible with a fluid mediated event occurring on a regional scale induced by tectonic stress of alleghenian late palaeozoic age

the influence of geological factors on the mechanical properties of basic igneous rocks used as road surface aggregates abstract the research described in this paper is performed on igneous rocks of basic composition the mechanical parameters analyzed are impact value flakiness value abrasion value and durability the relationship between these mechanical strength indices and the geological parameters is described by multiple regression analyses of all independent variables the mean grain mineral size has the greatest impact on the mechanical strength of the rocks the strength increases as the mean grain size decreases the effect is strongest for mean grain sizes under 1 mm there is also a significant reduction of the mechanical strength as a function of an increase in amphibole decrease in pyroxene contents and the degree of metamorphic alteration of the rocks

characteristics and petroleum origin of the carboniferous volcanic rock reservoirs in the shixi bulge of junggar basin western china abstract shixi bulge of the central junggar basin in western china is a unique region that provides insight into the geological and geochemical characteristics of large scale petroleum reservoirs in volcanic rocks of the western central asian orogenic belt carboniferous volcanic rocks in the shixi bulge mainly consist of striped lava and agglomerate as well as breccia lava and tight tuff volcanic rocks differ in porosity and permeability striped lava exhibits the highest porosity average 14 2 but the lowest permeability average 0 67 10 15 m among the rock types primary gas pores are widely developed and mostly filled secondary dissolution pores and fractures are two major reservoir storage spaces capillary pressure curves suggest the existence of four pore structure types of reservoir rocks several factors namely lithology pore structure and various diagenesis govern the physical properties of volcanic rocks the oil is characterized by a high concentration of tricyclic terpane a terpane distribution of c 23 21 c 20 and sterane distributions of c 27 28 29 and c 27 c 28 29 oil and gas geochemistry revealed that the oil is a mixture derived primarily from p 2 w source rock and secondarily from p 1 j source rock in the sag west of pen 1 well the gases are likely gas mixtures of humic and sapropelic organic origins with the sapropelic gas type dominant in the mixture the gas mixture is most likely cracked from kerogen rather than oils the carboniferous volcanic reservoirs in shixi bulge share some unique characteristics that may provide useful insights into the various roles of different volcanic reservoir types in old volcanic provinces the presence of these reservoirs will undoubtedly encourage future petroleum exploration in volcanic rocks up to the deep parts of sedimentary basins

the 20 hz signals of finback whales balaenoptera physalus the 20 hz signals of finback whales balaenoptera physalus were analyzed from more than 25 years of recordings at a variety of geographic locations on near surface hydrophones close to whales and on deep hydrophone systems these signals were composed of 1 s pulses of sinusoidal waveform with downward sweeping frequency from approximately 23 to 18 hz at variable source levels up to 186 db re 1 pa at 1 m usually with slightly lower levels for the pulses at the beginning and end of sequences these 20 hz pulses were produced in signal bouts separated by more than 2 h lasting as long as 32 5 h bouts were composed of regularly repeated pulses at intervals of 7 26 s typically either at one nominal pulse rate or at two alternating doublet pulse intervals signal bouts were interrupted by rests of 1 20 min at roughly 15 min intervals and by irregular gaps lasting between 20 and 120 min the distribution of these signals throughout the year and their temporal sequence were analyzed from the cont

effects of hydrothermal alterations on physical and mechanical properties of rocks in the kuril kamchatka island arc abstract the hydrothermal systems of the kuril kamchatka island arc are hosted in volcanic formations of neogene quaternary age thermal water alters volcanic rocks and transforms them into hydrothermal rocks such as secondary quartzites various propylites zeolitic rocks argillic rocks clays opalites and quartz feldspar metasomatites mineralogical alteration of rocks contributes to changes of their physical and mechanical properties the relationship between type of hydrothermal alteration and rock properties is quite variable and depends on a number of factors including parent rocks conditions chemical composition and type of fluid and duration of fluid rock interaction the study showed that high temperature fluids cause consolidation and strengthening of rock decrease in their porosity and permeability and remove hygroscopic moisture this tendency is observed independently of fluid chemical composition property variations caused by low temperature subsurface fluids are more complicated and diverse but their deterioration prevails i e a decrease in density strength and elastic modulus formation of secondary porosity high hygroscopy softening and swelling in water saturated environment special attention is given to the near surface alteration zones which affects the selection of sites for power plant construction and can impact the integrity of their foundation the subsurface horizon of hydrothermal clays is the most problematic zone due to high porosity plasticity hygroscopy compressibility and occasionally swelling

aqueous alteration of the bali cv3 chondrite evidence from mineralogy mineral chemistry and oxygen isotopic compositions abstract a petrographic geochemical and oxygen isotopic study of the bali cv3 carbonaceous chondrite revealed that the meteorite has undergone extensive deformation and aqueous alteration on its parent body deformation textures are common and include flattened chondrules a well developed foliation and the presence of distinctive 100 planar defects in olivine the occurrence of alteration products associated with the planar defects indicates that the deformation features formed prior to the episode of aqueous alteration the secondary minerals produced during the alteration event include well crystallized mg rich saponite framboidal magnetite and ca phosphates the alteration products are not homogeneously distributed throughout the meteorite but occur in regions adjacent to relatively unaltered material such as veins of altered material following the foliation the alteration assemblage formed under oxidizing conditions at relatively low temperatures oxygen isotopic compositions for unaltered regions in bali fall within the field for other cv3 wholerocks however the oxygen isotopic compositions of the heavily altered material lie in the region for the cm and cr chondrites the heavy isotope enrichment of the altered regions in bali suggest alteration conditions similar to those for the petrographie type 2 carbonaceous chondrites

magnetic hysteresis properties of greigite fe3s4 and a new occurrence in holocene sediments from swedish lappland a new occurrence of ferrimagnetic greigite fe3s4 is reported in freshwater holocene sediments from gaskkamus gorsajavri in swedish lappland the presence of greigite was inferred from the mineral magnetic analysis of sediment cores the greigite bearing sediments possess a high saturation isothermal remanent magnetisation to susceptibility sirm ratio a characteristic shared by other natural sediments known to contain greigite the hysteresis properties measured using a vibrating sample magnetometer of natural greigite extracted from lake sediments show much higher saturation coercivity b0 c and mrsms ratio values approximately 50 mt and 0 5 respectively than synthetic samples of greigite approximately 12 mt and 0 2 the results suggest that synthetic greigite samples contain crystals ranging from small non remanence carrying superparamagnetic grains to large multi domain grains in contrast the natural samples probably consist predominantly of pseudo single domain and single domain crystals capable of carrying a chemical remanent magnetisation however the unstable nature of greigite under laboratory conditions creates difficulty in characterising its physical attributes

seismic constraints on shallow crustal emplacement processes at the fast spreading east pacific rise we present the results of nine on bottom seismic refraction experiments carried out over young east pacific rise crust the experiments are unusual in that both the source and receiver are located within a few meters of the seafloor allowing high resolution determinations of shallow crustal structure three experiments were located within the axial summit caldera asc over zero age crust the seismic structure at these three locations is fundamentally the same with a thin 60 m surficial low velocity 2 5 km s layer a 100 to 150 m thick transition zone with velocities increasing by 2 5 km s and a layer with velocities of 5 km s at a depth beneath the seafloor of 130 190 m the surficial low velocity layer and transition zone are defined as seismic layer 2a and the 5 km s layer is defined as the top of layer 2b both the surficial low velocity layer and the transition zone double in thickness within 1 km of the rise axis we model layer 2a as the extrusive sequence and transition zone and the 2a 2b boundary as the top of the sheeted dikes the primary implication of this interpretation is that the depth to the top of the sheeted dikes deepens from 150 m to 300 m within 1 km of the asc the thickening of the extrusive layer is interpreted to be due to lava that either overflows the asc walls is emplaced through eruptions outside of the asc or travels laterally from the asc through conduits the most probable cause for the thickening of the transition zone is sill emplacement outside of the asc either from magma that does not reach the surface in an off axis eruption or magma that is transported laterally during the drainage process creating the asc we suggest that the mechanism controlling the magnitude and rate of the dike subsidence is the mechanism that determines the thickness of the extrusive section and the total thickness of layer 2a

geology of the sunbeam and grouse creek gold silver deposits yankee fork mining district eocene challis volcanic field idaho a volcanic dome and volcaniclastic hosted epithermal system the sunbeam and grouse creek epithermal gold silver deposits lie within the custer graben of the eocene challis volcanic field in central idaho the custer graben is a major northeast trending volcano tectonic depression that forms part of the trans challis fault system a 220 km long by 65 km wide zone defined by regional high angle faults grabens and cauldron subsidence features the relationship between the cauldrons and grabens along the trans challis fault zone northeast of the deposit area bears a strong resemblance to that observed in the east african rift system the challis volcanic field consists of a lower sequence of andesitic lavas and an upper sequence of quartz latitic and rhyolitic ash flow tuffs capping lacustrine and fluvial sedimentary rocks and late stage rhyolitic dikes domes and flows the sunbeam deposit is hosted by a subaerial rhyolitic flow dome complex and underlying pyroclastic rocks ore grades occur principally along dominant northeast and subordinate northwest trending fractures that are focused in silicified and argillized zones individual mineralized fractures manifested as either iron rich clayey zones with silicified cores and or margins or stockworks with anastomosing veinlets of silica and pyrite hydrothermal breccias are common and follow the regional structural fabric gold and silver occur primarily as electrum silver sulfides and sulfosalts are minor pyrite and arsenopyrite are the dominant sulfide minerals the silver to gold ratio is 6 1 argillically altered areas consist primarily of illite with less than 15 percent interlayered smectite pyrophyllite is present in the interior of the ore zones smectite exceeds 15 percent beyond the ore zones kaolinite is rare and alunite is absent oxidation is supergene in origin and forms a thin 12 to 30 m 40 100 ft cap to the deposits the grouse creek deposit is hosted by subaqueous volcaniclastic and pyroclastic rocks that are located within a subbasin immediately adjacent to and northwest of the sunbeam rhyolite flow dome the deposit is interpreted to be partly epigenetic and partly syngenetic ore occurs dominantly in silicified zones invading the same rhyolitic pyroclastic unit that hosts part of the sunbeam deposit in hydrothermal volcanic breccias and in the basal portion of the carbonaceous black shale which caps the sequence northeast and northwest trending fractures form the feeders for the hydrothermal system but have less influence on precious metal deposition than at the sunbeam deposit ore minerals are similar to those at the sunbeam deposit however the silver to gold ratio is roughly 43 1 argillic alteration and silicification encase the ore zones silicification is closely associated with ore grades whereas argillically altered rocks extend beyond the limits of ore grade propylitic alteration is widespread in the footwall of the ore zone regional structural and lithologic investigations and detailed geologic studies of both deposits indicate that the two deposits are contemporaneous but were deposited in different host environments the sunbeam deposit formed in a subaerial rhyolite flow dome that flanks the southern margin of the northeast trending rift valley lake in which the grouse creek deposit formed geochemical and mineralogical patterns in the host sedimentary sequence at the grouse creek deposit indicate that hydrothermal activity occurred during sediment accumulation most of the precious metals were deposited below the sediment water interface however warmer metal rich brines penetrated the sediment surface to form hydrothermal plumes which provided nutrients for biological blooms near the vent areas subsequent volcaniclastic sedimentation covered the deposit and its near surface manifestation the geologic environment of the custer graben and the sunbeam and grouse creek area bears strong resemblance to intracratonic rift environments such as the east africa rift system

pyrite framboids and their development a new conceptual mechanism it has been suggested that the two morphologies of sedimentary pyrite framboids and euhedra may reflect two distinct pathways of pyrite formation framboids form indirectly via iron monosulphides whereas euhedra form from direct precipitation from solution a third pathway which is bridging these two forms is proposed here namely the continuous growth from a monosulphide globule through framboids to a euhedral single crystal it is also suggested that framboids probably occur over a range of three orders of magnitude from the least complex microframboids through framboids to polyframboids

petrographic features as an effective indicator for the variation in strength of granites abstract the textural characteristics of four different granites from the lower himalayan regime in north western pakistan have been examined in relation to their effect on the mechanical nature of rock detailed petrographic examination and subsequent quantitative qemscan analysis provide better understanding of the difference between their textures three of the granite types are slightly altered grade ii whereas the other has a higher degree of alteration and corresponds to alteration grade iii the mechanical properties determined for each granite type include unconfined compressive and tensile strength elastic modulus p wave velocity schmidt hardness and dry density statistical analyses combined with post test petrography demonstrate textural control on mechanical properties the important petrographic characteristics influencing mechanical behaviour include modal concentration and grain size of individual minerals mean grain size of rock and distribution of grain size within a rock recrystallization of minerals along boundaries has a pronounced effect on increased strength of granites texture however has a significant influence on the variation of strength of granites with similar alteration grade

a double difference method for high resolution acoustic tracking using a deep water vertical array ray tracing is typically used to estimate the depth and range of an acoustic source in refractive deep water environments by exploiting multipath information on a vertical array however mismatched array inclination and uncertain environmental features can produce imprecise trajectories when ray tracing sequences of individual acoustic events double difference methods have previously been developed to determine fine scale relative locations of earthquakes along a fault waldhauser and ellsworth 2000 bull seismolog soc am 90 1353 1368 this technique translates differences in travel times between nearby seismic events recorded at multiple widely separated stations into precise relative displacements here this method for acoustic multipath measurements on a single vertical array of hydrophones is reformulated changes over time in both the elevation angles and the relative arrival times of the multipath are converted into relative changes in source position this approach is tested on data

monitoring pacific ocean seismicity from an autonomous hydrophone array since may 1996 an array of autonomous hydrophone moorings has been continuously deployed in the eastern equatorial pacific to provide long term monitoring of seismic activity including low level volcanic signals along the east pacific rise between 20 n and 20 s and the galapagos ridge the instruments and moorings were designed to continuously record low frequency acoustic energy in the sofar channel for extended periods and produce results comparable to those previously derived by using the u s navy sound surveillance system sosus in the northeast pacific the technology and methodology developed for this experiment including instrument design mooring configuration analysis software location algorithms with an analysis of errors and a predicted error field are described in detail volcanic activity is observed throughout the pacific along with seismicity along transform faults subduction zones and intraplate regions comparison data sets indicate detection thresholds and accuracy better than the land networks for open ocean areas and results comparable to or better than sosus volcanic seismicity along the fast spreading east pacific rise appears similar to documented examples in the northeast pacific but with much shorter durations one example from the intermediate spreading galapagos ridge is comparable to northeast pacific examples and several episodes of activity were observed in the wilkes transform fault zone a site of continuing off axis seismicity is located near 18 s and 116 w isolated intraplate earthquakes are observed throughout the study area earthquake information from this experiment and future observations will be provided through the world wide web and earthquake data centers

phyllosilicates and zeolite assemblages in the carbonate periplatform of the great bahama bank origin and relation to diagenetic processes odp leg 166 sites 1006 and 1007 abstract the western flank of the great bahama bank drilled during odp leg 166 at seven sites represents a prograding carbonate sequence from late oligocene to holocene eberli et al proc odp init reports 166 1997 the signatures of the detrital input and of diagenetic alteration are evident in clay enriched intervals from the most distal sites 1006 and 1007 in the straits of florida mineralogical and chemical investigations xrd tem sem icp ms run on bulk rocks and on the clay fractions enable the origin and evolution of silicate parageneses to be characterized plio pleistocene silt and clay interbeds contain detrital clay assemblages comprising chlorite illite interstratified illite smectite smectite kaolinite and palygorskite the greater smectite input within late pliocene units than in pleistocene oozes may relate either varying source areas or change in paleoclimatic conditions and weathering intensity the clay intervals from miocene upper oligocene wackestone sections are fairly different with prevalent smectite in the fine fraction whose high crystallinity and mg contents that point towards an authigenic origin the lower miocene section below 1104 mbsf at depths where compaction features are well developed is particularly characterized by abundant authigenic na k clinoptilolite filling foraminifer tests the authigenic smectite and clinoptilolite paragenesis is recorded by the chemical trends both of the sediment and the interstitial fluid this diagenetic evolution implies si and mg rich fluids circulating in deeper and older sequences for lack of any local volcaniclastic input the genesis of zeolite and the terms of water rock interaction are discussed the location of the diagenetic front correlates with that of the seismic sequence boundary p2 dated as 23 2 ma this correspondence may allow the chronostratigraphic significance of some specific seismic reflections to be reassessed

the development and application of the alteration strength index equation abstract we have developed an alteration strength index asi equation to address the effect of hydrothermal alteration on mechanical rock properties this equation can be used to estimate a range of rock strengths comparable to uniaxial compressive strength ucs based on rapid analysis of mineralogy and microstructure we used rock samples from three geothermal fields in the taupo volcanic zone tvz to represent a range of alteration types these are sedimentary intrusive and extrusive rocks typical of geothermal systems from shallow and deep boreholes 72 measured depth md to 3280 md the parameters used in asi were selected based on literature relating these aspects of mineralogy and microstructure to rock strength the parameters in asi define the geological characteristics of the rock such as proportions of primary and secondary mineralogy individual mineral hardness porosity and fracture number we calibrated the asi against measured ucs for our samples from the tvz to produce a strong correlation r2 of 0 86 and from this correlation we were able to derive an equation to convert asi to ucs because the asi ucs relationship is based on an empirical fit the ucs value that is obtained from conversion of the asi includes an error of 7 mpa for the 50th percentile and 25 mpa for the 90th percentile with a mean error of 11 mpa a sensitivity analysis showed that the mineralogy parameter is the dominant characteristic in this equation and the asi equation using only mineralogy can be used to provide an estimated ucs range although the error or uncertainty becomes greater this provides the ability to estimate strength even when either fracture or porosity information are not available for example in the case of logging drill cuttings this research has also allowed us to provide ranges of rock strengths based solely on the alteration zones mineralogy and depth of lithologies found in a typical geothermal field that can be used to update conceptual models of geothermal fields

20 hz pulses and other vocalizations of fin whales balaenoptera physalus in the gulf of california mexico low frequency vocalizations were recorded from fin whales b a l a e n o p t e r a p h y s a l u s in the gulf of california mexico during three cruises in march 1985 recorded 20 hz pulses were in sequences of regular 9 s interpulse intervals in august 1987 nearly all were in sequences of doublets with alternating 5 and 18 s interpulse intervals no 20 hz pulse sequences of any kind were detected in february 1987 the typical pulse modulated from 42 to 20 hz and its median duration was 0 7 s 1985 data most other fin whale sounds were also short tonal pulses averaging 82 56 and 68 hz respectively for the three cruises 89 were modulated in frequency mostly downward compared to atlantic and pacific ocean regions gulf of california 20 hz pulses were unique in terms of frequency modulation interpulse sound levels and temporal patterns fin whales in the gulf may represent a regional stock revealed by their soundcharacteristics a phenomenon previously shown for humpback whales birds and fish regional differences in fin whale sounds were found in comparisons of atlantic and pacific locations

tracking blue whales in the eastern tropical pacific with an ocean bottom seismometer and hydrophone array low frequency northeastern pacific blue whale calls were recorded near the northern east pacific rise 9 degrees n latitude on 25 ocean bottom mounted hydrophones and three component seismometers during a 5 day period november 22 26 1997 call types a b c and d were identified the most common pattern being approximately 130 135 s repetitions of the ab sequence that for any individual whale persisted for hours up to eight individual blue whales were recorded near enough to the instruments to determine their locations and were tracked call by call using the b components of the calls and a bayesian inversion procedure for four of these eight whales the entire call sequences and swim tracks were determined for 20 26 h periods the other whales were tracked for much shorter periods the eight whales moved into the area during a period of airgun activity conducted by the academic seismic ship r v maurice ewing the authors examined the whales locations and call characteristics with respect to the periods of airgun activity although the data do not permit a thorough investigation of behavioral responses no correlation in vocalization or movement with airgun activity was observed

tracking fin whales in the northeast pacific ocean with a seafloor seismic network ocean bottom seismometer obs networks represent a tool of opportunity to study fin and blue whales a small obs network on the juan de fuca ridge in the northeast pacific ocean in 2 3 km of water recorded an extensive data set of 20 hz fin whale calls an automated method has been developed to identify arrival times based on instantaneous frequency and amplitude and to locate calls using a grid search even in the presence of a few bad arrival times when only one whale is calling near the network tracks can generally be obtained up to distances of 15 km from the network when the calls from multiple whales overlap user supervision is required to identify tracks the absolute and relative amplitudes of arrivals and their three component particle motions provide additional constraints on call location but are not useful for extending the distance to which calls can be located the double difference method inverts for changes in relative call locations using differences in residuals for pairs of nearby calls recorded on a common station the method significantly reduces the unsystematic component of the location error especially when inconsistencies in arrival time observations are minimized by cross correlation

relationships among mechanical physical and petrographic properties of siwalik sandstones central nepal sub himalayas abstract mechanical and physical characteristics of rocks generally depend on their composition and texture because they are reflective of their environments during sedimentation diagenesis and weathering in each location to understand this relationships between mechanical and physical indices and composition and texture have been analyzed using several rock samples obtained from mio pleistocene sandstone sequence of the siwalik group widely distributed in foothills of the nepal himalayas sandstones are quartzo feldspathic to quartzo lithic and quartzo feldspathilithic cement matrix and void vary from 6 to 41 0 to 18 and 1 to 12 respectively ferroan calcitic and siliceous cements are the dominant cements and their ratio to total cement varies from 0 2 to 1 0 packing density of sandstones ranges from 59 to 95 clasts are loosely to closely packed and are weakly to strongly bonded by cement results of correlation analyses show that sandstones strongly depend on several indices that is percent void strong cement over total cement strong over weak contacts concavo convex contacts and packing density most of which are measured on thin sections contrarily they depend little on grain size shape mineralogical maturity index and the other petrographic indices increased interlocking and strong cementing with reduced void tends to possess high densities low porosity and offer good resistance against deformation therefore proportion of strong cement over total cement void content strong over weak contacts grain to void contact concavo convex contact and packing density are meaningful indices considering the sandstones of the siwalik group based on the multiple regression correlation analyses and then stepwise multiple regression analysis some regression equations with significant explanatory indices are indicated for estimating mechanical and physical properties in other words such relationships may be useful in estimating mechanical and physical properties using the significant petrographic indices

direct measurements of oceanic crustal density at the northern juan de fuca ridge density and porosity of oceanic crust are critically important to understanding the circulation of hydrothermal fluid at mid ocean ridges to determine these parameters directly we completed a fixed on bottom gravity survey on the endeavour segment of the juan de fuca ridge which is a well studied spreading center that is both hydrothermally and tectonically active a bell aerospace gravity meter mounted within the submersible alvin was used to make gravity measurements from the floor of the axial valley to the summit of the west axial ridge analysis of these data gave a density of 2240 50 kg m 3 for the upper 130 m of crust comparison of the outcrop density with that of recovered rock samples resulted in a calculated porosity of 38 4 forward modeling of the seafloor gravity data indicated that both the valley floor and bounding walls have unusually low density crust that is flanked by higher density crust

constraints on the dynamics and spatio temporal evolution of the 2011 oichalia seismic swarm sw peloponnesus greece abstract in this paper we present a detailed study of a shallow seismic swarm which took place in the area of oichalia sw peloponnesus between august and december 2011 the seismic crisis started on 14 8 2011 with an mw 4 8 earthquake and was followed by more than 1600 events several of which having magnitude over 4 0 the activity was recorded by local temporary and regional permanent seismic stations thousands of records were collected and routinely analyzed p and s wave arrival times were manually picked and incorporated in the hypoinverse algorithm together with a new optimum local velocity model hypocentral solutions were improved by applying a double difference method focal mechanisms show that the activated fault zone is dominated by dip slip normal faulting trending nnw sse with the average t axes orientation being n70 e consistent with regional tectonics we have investigated towards stress triggering and fluid diffusion by employing coulomb stress transfer spatio temporal and frequency magnitude distribution fmd analyses the negligible coulomb stress transfer and seismicity rate changes that were calculated imply for a stress deficit in the broader study area hence an external triggering mechanism is required to justify the observed pattern the b values increase towards the sse compatible with the similarly directed migration of seismicity showed that the oichalia swarm could possibly be adapted to an epidemic type aftershock sequence model etas fluid diffusion is reflected in the spatio temporal hypocenter migration clustering analysis combined with the temporal distribution of b values has shown that the swarm evolved in three major phases the first two being initiated by major events which were probably triggered externally due to fluid injection that brought the seismogenic volume into a critical state likely followed by afterslip the last phase signified a relaxation period with dispersed seismicity throughout the area and the b values gently diminishing towards unity

microcracks in ultrabasic rocks under uniaxial compressive stress the initiation and propagation of microcracks under stress are highly dependent upon the mineralogical and textural characteristics of the various lithotypes detailed observation and quantification of microcracks before and after uniaxial compression test were conducted a fresh olivine rich harzburgite and a serpentinized dunite were analyzed collected from the pindos and vourinos ophiolites northern greece respectively in order to compare their microcrack patterns quantitative analysis indicated that during uniaxial compression the intragranular microcracks which are the dominating crack type are gradually transformed or organized into transgranular cracks some of the newly formed transgranular cracks may also be a result of the growth of existing grain boundary cracks the new intragranular microcracks in the olivine rich harzburgite are oriented predominantly parallel to the compressive stress direction while those in the serpentinized dunite show a scattered orientation presumably due to the mesh texture of this rock type the new transgranular cracks of both peridotites tend to be subparallel to the compressive stress direction however many of them show a random orientation due to the fact that they have been formed as a result of the propagation of grain boundary cracks the occurrence of the soft serpentine along fracture surfaces of olivine when it is in assemblage with orthopyroxene tends to absorb the applied stress hampering the development of microcracks in olivine on the other hand in serpentinized peridotites the microcracks are enhanced in olivine because it is surrounded by large amounts of the much softer and flexible serpentine microcracks are usually formed along the cleavage planes of orthopyroxene porphyroclasts indicating that such crystallographic preferred orientations act as planes of weakness controlling the direction of the crack paths cr spinel grains likely comprise locations of initiation of microcracks due to their very hard nature and different mechanical behaviour relative to the surrounding silicate phases knowledge of the mineralogical and textural characteristics may assist in the prediction of potential development of failure surfaces of an ultrabasic rock in service

correlation of mineralogical and textural characteristics with engineering properties of selected granitic rocks from turkey abstract granitic rocks show a variety of engineering properties that may affect quarrying operations tunneling mining slope stability and the use of rock as a construction material the physical and mechanical properties are a function of the mineralogical and textural characteristics of the rock the purpose of this study is to apply correlation analysis to investigate the relationships between petrographical and engineering properties of granitic rocks a variety of granitic rock samples from different parts of turkey were subjected to petrographic studies the same samples were then tested to determine specific gravity dry and saturated unit weight water absorption effective and total porosity sonic velocity schmidt hardness point load strength index uniaxial compressive strength tensile strength and modulus of elasticity the relationships between these properties and the petrographical characteristics are described by simple regression analyses the study revealed that the influence of the textural characteristics on the engineering properties appears to be more important than the mineralogy it also determined that the types of contacts grain mineral shape and size significantly influence the engineering properties of the granitic rocks

range estimation of bowhead whale balaena mysticetus calls in the arctic using a single hydrophone bowhead whales generate low frequency calls in shallow water arctic environments whose dispersive propagation characteristics are well modeled by normal mode theory as each mode propagates with a different group speed a call s range can be inferred by the relative time frequency dispersion of the modal arrivals traditionally at close ranges modal arrivals are separated using synchronized hydrophone arrays here a nonlinear signal processing method called warping is used to filter the modes on just a single hydrophone the filtering works even at relatively short source ranges where distinct modal arrivals are not separable in a conventional spectrogram however this warping technique is limited to signals with monotonically increasing or decreasing frequency modulations a relatively common situation for bowhead calls once modal arrivals have been separated the source range can be estimated using conventional modal dispersion techniques with the original source signal structure being recovered as a by product twelve bowhead whale vocalizations recorded near kaktovik alaska in 2010 with signal to noise ratios between 6 and 23 db are analyzed and the resulting single receiver range estimates are consistent with those obtained independently via triangulation from widely distributed vector sensor arrays geoacoustic inversions for each call are necessary in order to obtain the correct ranges

fin whale tracks recorded by a seismic network on the juan de fuca ridge northeast pacific ocean fin whale calls recorded from 2003 to 2004 by a seafloor seismic network on the endeavour segment of the juan de fuca ridge were analyzed to determine tracks and calling patterns over 150 tracks were obtained with a total duration of 800 h and swimming speeds from 1 to 12 km h the dominant inter pulse interval ipi is 24 s and the ipi patterns define 4 categories a 25 s single ipi and 24 30 s dual ipi produced by single calling whales a 24 13 s dual ipi interpreted as two calling whales and an irregular ipi interpreted as groups of calling whales there are also tracks in which the ipi switches between categories call rates vary seasonally with all the tracks between august and april from august to october tracks are dominated by the irregular ipi and are predominantly headed to the northwest suggesting that a portion of the fin whale population does not migrate south in the fall the other ipi categories occur primarily from november to march these tracks have slower swimming speeds tend to meander and are predominantly to the south the distribution of fin whales around the network is non random with more calls near the network and to the east and north

localization of marine mammals near hawaii using an acoustic propagation model humpback whale songs were recorded on six widely spaced receivers of the pacific missile range facility pmrf hydrophone network near hawaii during march of 2001 these recordings were used to test a new approach to localizing the whales that exploits the time difference of arrival time lag of their calls as measured between receiver pairs in the pmrf network the usual technique for estimating source position uses the intersection of hyperbolic curves of constant time lag but a drawback of this approach is its assumption of a constant wave speed and straight line propagation to associate acoustic travel time with range in contrast to hyperbolic fixing the algorithm described here uses an acoustic propagation model to account for waveguide and multipath effects when estimating travel time from hypothesized source positions a comparison between predicted and measured time lags forms an ambiguity surface or visual representation of the most probable whale position in a horizontal plane around the array this is an important benefit because it allows for automated peak extraction to provide a location estimate examples of whale localizations using real and simulated data in algorithms of increasing complexity are provided

physical properties of indus ophiolites from kashmir himalaya abstract the indus suture rocks from the dras sanko kargil regions have been studied for their petrography chemical and physical properties seismic velocities as a function of pressure up to 10 kbar are obtained on different rock types of the ophiolite assemblage such as spilite metabasalt schist dunite peridotite pyroxenite serpentinite metagreywacke and associated granodiorite empirical relations of density versus velocity density versus porosity the results of anisotropy due to multidirectional measurements of velocity data of static strength and dynamic moduli and regression analysis of stress strain data are presented they exhibited low anisotropy and high strength the exceptions being those that are serpentinized the metamorphism of the regional rocks the consequent hydrothermal alteration the degree of serpentinization in the ultramafics and the groundmass to phenocryst ratio amongst the metabasics are found to influence the physical properties thermal studies yielded the results of the increase in expansion of the decrease in density and the dependence of on the porphyritic mineral content the absence of a definite sequential association as well as a lack of metamorphic contact in the area between the ultramafics and metavolcanics and the differing compatible nature in the pressure velocity modelling results the ultramafics gabbros dykes being compatible with the oceanic rocks and ophiolites while the metavolcanics are incompatible suggest the dismembered nature of the indus ophiolites

corehole seismometer development for low noise seismic data in a long term seafloor observatory longstanding problems unique to marine seismology in contrast to land based studies include high levels of environmental noise unpredictable instru ment placement short measurement duration and lim ited numbers of instruments traditional instruments are deployed and recovered from a surface ship with no capability to verify data acquisition until the end of the experiment they are often poorly sited and usu ally poorly coupled to the seafloor experiments have typically been short in duration with only a minimum number of instruments the result of these logistical problems is high background noise sparse data recov ery compared to continental stations and low fidelity data in an effort to solve many of these problems we have developed and deployed corehole seismometers 1 90 hz into small boreholes drilled by an underwa ter drilling system using a tethered remotely operated vehicle rov the results are seismic data with a sig nificantly lower background noise level a lower thresh old for recognition of small events well oriented and useable horizontal seismograms and a much longer de ployment capability we present new data from these instruments and compare them with data from two types of traditional instruments deployed from a sur face ship these contemporaneous deployments were conducted during 1996 and 1997 in monterey bay

establishing a new era of submarine volcanic observatories cabling axial seamount and the endeavour segment of the juan de fuca ridge abstract at least 70 of the volcanism on earth occurs along the 65 000 km network of mid ocean ridge mor spreading centers within these dynamic environments the highest fluxes of heat chemicals and biological material from the lithosphere to the hydrosphere occur during volcanic eruptions however because underwater volcanoes are difficult and expensive to access researchers are rarely if ever in the right place at the right time to characterize these events therefore our knowledge is limited about the linkages among hydrothermal chemical and biological processes during seafloor formation and crustal evolution to make significant advancements in understanding the evolution of mor environments the united states and canada have invested in the first plate scale submarine cabled observatory linked through the global internet spanning the juan de fuca tectonic plate these two networks include 1700 km of cable and 14 subsea terminals that provide 8 10 kw power and 10 gbs communications to hundreds of instruments on the seafloor and throughout the overlying water column resulting in a 24 7 365 presence in the oceans data and imagery are available in real to near real time the initial experimental sites for monitoring volcanic processes include the mor volcanoes called axial seamount and the endeavour segment that are located on the juan de fuca ridge axial a hot spot influenced seamount is the most robust volcano along the ridge rising nearly 1400 m above the surrounding seafloor and it has erupted twice in the last 15 years in contrast the endeavour segment is characterized by more subdued topography with a well defined axial rift and it hosts one of the most intensely venting hydrothermal systems known a non eruptive spreading event lasting 6 years was documented at endeavour between 1999 and 2005 hydrothermal venting intensity chemistry and temperature as well as associated biological communities at both sites were significantly perturbed by the magmatic and intrusive events this paper presents the similarities and differences between the axial and endeavour volcanic systems and identifies reasons why they are ideal candidates for comparative studies the u s has made a 25 year commitment for sustained observations using the cabled infrastructure the highly expandable nature of submarine optical networking will allow for the future addition of novel experiments that utilize ever evolving advancements in computer sciences robotics genomics and sensor miniaturization comprehensive modeling of the myriad processes involved will continue to assimilate and integrate growing databases yielding a new understanding of integrated processes that create the seafloor in the global ocean basins

diagenetic formation of ferrimagnetic iron sulphide minerals in rapidly deposited marine sediments south island new zealand abstract detailed magnetostratigraphic studies of late neogene siliciclastic sediments of the awatere group south island new zealand 41 45 s 174 05 e have revealed a wide range of palaeomagnetic behaviour examination of rock magnetic properties was undertaken using conventional palaeomagnetic techniques and thermomagnetic x ray diffraction and electron microprobe analyses these analyses indicate that the ferrimagnetic iron sulphide minerals greigite and pyrrhotite are responsible for a stable and intense magnetic remanence in fine grained sediments whereas titanomagnetite is the only remanence bearing mineral identified in coarser grained sediments which are less strongly and less stably magnetised than the fine grained sediments detrital titanomagnetite grains are likely to have undergone dissolution during early diagenesis as a result of iron sulphide formation which occurs commonly in rapidly deposited anoxic sediments that support active sulphate reduction and h 2 s formation preservation of greigite and pyrrhotite is inferred to result from the arrest of the pyritisation process probably due to the low permeability of the fine grained sediments and consumption of available h 2 s before full reaction to pyrite occurred relative palaeomagnetic instability and weak remanence intensities in coarser grained sediments is likely to be due to low titanomagnetite concentrations resulting from titanomagnetite dissolution

sulphur speciation and pyrite formation in meromictic ex fjords abstract powell and sakinaw lakes are stably stratified ex fjords which became isolated from the strait of georgia approximately 11000 years ago by emerged sills due to post glacial isostatic rebound both lakes contain highly sulphidic relict seawater powell 3 0 mm sakinaw 5 5 mm at depth chemically analogous to porewaters of reducing marine sediments sakinaw has a very sharp chemocline located just below the oxic anoxic interface whereas in powell the interface is spread out over 200 m of the water column sulphate is present in the oxic part of the water column at much higher concentrations in sakinaw lake up to 65 m than in powell lake 10 m and increases in concentration with depth until reaching the interface below which it is rapidly depleted sulphur oxyanions of intermediate oxidation state thiosulphate sulphite and tetrathionate are not detectable in either lake particulate elemental sulphur was also not found in either lake high concentrations of reduced iron and hydrogen sulphide result in formation of iron monosulphides and pyrite in the anoxic water columns of both lakes the presence of these two minerals correlates well with their calculated saturation states pyrite precipitates with no apparent monosulphide precursor at depths where dissolved sulphide concentrations are low and monosulphide phases are undersaturated as sulphide levels increase at greater depths the waters become saturated with respect to iron monosulphides and particulate fes species are detected in the water column the large separation of the oxic anoxic interface and the chemocline in sakinaw 10 m and especially in powell lake 100 m relative to that of sediment porewaters allows excellent resolution of these processes

estimating range to a vocalizing fin whale using the timing and amplitude of multipath arrivals a semi automated method is described to range to vocalizing fin whales using the timing and amplitude of multipath arrivals measured on seafloor receivers calls are detected and multipath arrivals identified with a matched filter multipath times and relative amplitudes are predicted as a function of range by ray tracing because the direct and first water column multiple arrivals are not always observed different hypotheses for the observed arrival paths must be considered for two arrivals an amplitude threshold is used to determine if the first arrival is the direct path and if not the call is disregarded as distant when three or more arrivals are detected three hypotheses for the paths of arrivals are considered the solution is the hypothesis and range that minimizes the timing and optionally amplitude ratio or absolute amplitude residual the method is tested with data from two ocean bottom seismometers one on the juan de fuca ridge and the other in the cascadia basin solutions obtained by

directional frequency and recording difar sensors in seafloor recorders to locate calling bowhead whales during their fall migration bowhead whales balaena mysticetus migrate west during fall 10 75 km off the north coast of alaska passing the petroleum developments around prudhoe bay oil production operations on an artificial island 5 km offshore create sounds heard by some whales as part of an effort to assess whether migrating whales deflect farther offshore at times with high industrial noise an acoustical approach was selected for localizing calling whales the technique incorporated difar directional frequency and recording sonobuoy techniques an array of 11 dasars directional autonomous seafloor acoustic recorders was built and installed with unit to unit separation of 5 km when two or more dasars detected the same call the whale location was determined from the bearing intersections this article describes the acoustic methods used to determine the locations of the calling bowhead whales and shows the types and precision of the data acquired calibration transmissions at gps measured times and locations provided measures of the individual dasar clock drift and directional orientation the standard error of the bearing measurements at distances of 3 4 km was 1 35 after corrections for gain imbalance in the two directional sensors during 23 days in 2002 10 587 bowhead calls were detected and 8383 were localized

petrographic characteristics of intrusive rocks as an evaluation tool of their technical properties the main petrographic variables of intrusive rocks that influence the technical test methods common used within the aggregate industry were identified and evaluated the aim being to investigate wh

framboidal pyrite early diagenetic late diagenetic and hydrothermal occurrences from the acton vale quarry cambro ordovician quebec

the influence of alteration on the engineering properties of dolerites the examples from the pindos and vourinos ophiolites northern greece abstract the influence of alteration on the physico mechanical properties of dolerites from the pindos and vourinos ophiolites northern greece is investigated quantitative petrographic analysis shows that the samples display various percentages of secondary minerals two new micropetrographic indices are calculated from the results of petrographic modal analysis for the engineering assessment of dolerites the micropetrographic strength index i ps and the replacement index i rep the samples are also tested to determine water absorption apparent density total porosity sand equivalent uniaxial compressive strength los angeles abrasion value aggregate impact value aggregate abrasion value and polished stone value the influence of alteration on the rock quality and especially the relationships between the proposed micropetrographic indices and the engineering parameters are determined using regression analysis and the derived equations were verified by the t test and the f test the relationships between the i ps and i rep indices and the engineering properties show that alteration products generally result in mechanically weaker rocks however the results of the physico mechanical tests indicate that dolerites retain their strength and durability due to the low proportions of soft minerals and microcracks along with the preservation of their igneous textures the polishing resistance is the only engineering parameter that is positively affected by alteration processes as expressed by the i ps index particularly the replacement of the primary mafic minerals by secondary minerals expressed by the i rep index can enhance the polishing resistance of dolerites when used in the wearing surface of a road the results also indicate strong positive correlations between the chlorite content and the water absorption and total porosity values

sound source localization technique using a seismic streamer and its extension for whale localization during seismic surveys marine seismic surveys are under increasing scrutiny because of concern that they may disturb or otherwise harm marine mammals and impede their communications most of the energy from seismic surveys is low frequency so concerns are particularly focused on baleen whales extensive mitigation efforts accompany seismic surveys including visual and acoustic monitoring but the possibility remains that not all animals in an area can be observed and located one potential way to improve mitigation efforts is to utilize the seismic hydrophone streamer to detect and locate calling baleen whales this study describes a method to localize low frequency sound sources with data recoded by a streamer beamforming is used to estimate the angle of arriving energy relative to sub arrays of the streamer which constrains the horizontal propagation velocity to each sub array for a given trial location a grid search method is then used to minimize the time residual for relative arrival times along the streamer estimated by cross correlation results from both simulation and experiment are shown and data from the marine mammal observers and the passive acoustic monitoring conducted simultaneously with the seismic survey are used to verify the analysis

greigite and the magnetic properties of sediments x ray diffraction spectra of freeze dried sediments from a lake in the english lake district positively identified the presence of greigite a magnetic iron sulfide fe3s4 mineral the sediments also show considerable loss of magnetic intensity when wet samples are allowed to oxidize several hypotheses have been proposed elsewhere to explain the intensity loss but an assessment of the evidence suggests that oxidation of greigite is responsible in these sediments data from several lakes and from laboratory experiments are used to deduce the environmental requirements for greigite formation these conditions of high labile c concentrations good sources of labile fe and s and an oscillating oxycline depth in the sediments are likely to be found only in mono or dimictic eutrophic lakes estuaries and salt marshes and are unlikely to be found in meromictic lakes unstratified lakes oligotrophic lakes or deep sea sediments

baleen whale distribution and seasonal occurrence revealed by an ocean bottom seismometer network in the western indian ocean abstract from the acoustic data acquired by the rhum rum reunion hotspot and upper mantle reunions unterer mantel ocean bottom seismometer obs network between october 2012 and november 2013 this study revealed baleen whale occurrence in the western indian ocean io low frequency songs from three species antarctic blue whales pygmy blue whales and fin whales as well as p calls or spot calls from an unknown species were recorded on the dataset the wide arrangement of the obs network 2000 km 2000 km provided valuable information to draw seasonal patterns of occurrence and distribution all over the area these species occurred sympatrically in the western io at least during austral autumn months emphasizing the importance of this region for these populations this data set helped to refine the knowledge on their spatio temporal distribution and complete the picture built by previous studies a tighter sub network of 8 obss deployed on the south west indian ridge provided ideal inter sensor spacing for whale tracking we demonstrated the capability of such array of detecting and tracking the three different whale species up to 50 km and for several hours as a result and to understand the effect of acoustic wave propagation songs from the tracking were described at a close and remote distance of the sensor this work could also help to understand the local behavior of these species during austral autumn months in this area of the western indian ocean

analysis and localization of blue whale vocalizations in the solomon sea using waveform amplitude data during the woodlark basin seismic experiment in eastern papua new guinea 1999 2000 an ocean bottom seismic array recorded marine mammal vocalizations along with target earthquake signals the array consisted of 14 instruments 7 of which were three component seismometers with a fourth component hydrophone they were deployed at 2 0 3 2 km water depth and operated from september 1999 through february 2000 while whale vocalizations were recorded throughout the deployment this study focuses on 3 h from december 21 1999 during which the signals are particularly clear the recordings show a blue whale song composed of a three unit phrase that song does not match vocalization characteristics of other known pacific subpopulations and may represent a previously undocumented blue whale song animal tracking and source level estimates are obtained with a bayesian inversion method that generates probabilistic source locations the bayesian method is augmented to include travel time estimates from seismometers and hydrophones and acoustic signal amplitude tracking results show the whale traveled northeasterly over the course of 3 h covering approximately 27 km the path followed the edge of the woodlark basin along a shelf that separates the shallow waters of the trobriand platform from the deep waters of the basin

assessment of the engineering behavior of ultramafic and mafic rocks using chemical indices geochemistry is of great importance for the interpretation of the geomechanical quality of rock materials used in various construction applications this paper investigates the interrelationships between selected chemical indices and various engineering parameters of ultramafic and mafic rocks from the vourinos pindos koziakas and othrys ophiolite complexes northern and central greece the significance of these indices for the engineering assessment of ophiolitic aggregates is strongly demonstrated based on statistical analysis of the experimental results the studied lithologies include dunites olivine rich harzburgites typical harzburgites plagioclase bearing lherzolites troctolites diorites and dolerites which show various degrees of alteration and tectonic deformation the effect of alteration on rock strength and particularly the relationships between specific chemical indices and the engineering parameters are determined using simple regression analysis the results designate that the wpi index is the most appropriate for the assessment of the engineering behavior of ultramafic lithologies while the loi index seems to provide a general estimation of the strength properties of mafic rocks

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