genesis of the huangshannan high ni tenor magmatic sulfide deposit in the eastern tianshan northwest china constraints from pge geochemistry and os s isotopes abstract the huangshannan magmatic ni cu sulfide deposit is one of a group of permian magmatic ni cu deposits located in the southern central asian orogenic belt in the eastern tianshan northwest china it is characterized by elevated ni tenor concentrations in recalculated 100 sulfide in sulfide within ultramafic rocks 9 19 wt with values much higher than other deposits in the region sulfides of the huangshannan deposit are composed of pentlandite chalcopyrite and pyrrhotite and the host rock is relatively fresh indicating that the high ni tenor is a primary magmatic feature rather than formed by alteration processes it is shown that sulfides with high ni tenor can be generated by sulfide olivine equilibrium at an oxygen fugacity of qfm 0 5 for magmas containing 450 ppm ni and 20 olivine ores with 10 wt sulfur have relatively low pge and ni tenors compared to other ores r factor mass ratio of silicate to sulfide liquid modeling of ni indicates that they formed at moderate r values 150 600 based on this constraint on r values ores with 4 5 wt as sulfide rich samples are also depleted in cu and as interstitial sulfides in those samples are physically interconnected at a scale of several cms the low pt and pd anomalies are attributed to solid pt and pd phases crystallization and retention with the monosulfide solid solution mss and cu rich sulfide liquid percolation during mss fractionation this finding indicates that pt anomalies in sulfide rich rocks from magmatic ni cu deposits in the eastern tianshan are the result of sulfide fractionation rather than a hydrothermal effect 187 os 188 os 278ma values of the lherzolite samples vary from 0 27 to 0 37 and os 278ma values vary from 110 to 189 indicating significant magma interaction with crustal sulfides rich in radiogenic os well constrained os values and 34 s values 0 4 to 0 8 indicate that crustal contamination occurred at depth before the arrival of the magma in the huangshannan chamber regionally deposits with high ni tenor have not been reported other than the huangshannan deposit however many intrusions with high ni contents in olivine are present in nw china such as the erhongwa poyi and poshi intrusions those intrusions are capable of forming high ni tenor sulfides due to olivine sulfide silicate equilibrium and relative high ni content in parent magma making them attractive exploration targets

sulfur in serpentinized oceanic peridotites serpentinization processes and microbial sulfate reduction the mineralogy contents and isotopic compositions of sulfur in oceanic serpentinites reflect variations in temperatures and fluid fluxes serpentinization of 1 ma peridotites at hess deep occurred at high temperatures 200 400 c and low water rock ratios oxidation of ferrous iron to magnetite maintained low o2 and produced a reduced low sulfur assemblage including nife alloy small amounts of sulfate reduction by thermophilic microbes occurred as the system cooled producing low 34s sulfide 1 5 to 23 7 in contrast serpentinization of iberian margin peridotites occurred at low temperatures 20 200 c and high water rock ratios complete serpentinization and consumption of ferrous iron allowed evolution to higher o2 microbial reduction of seawater sulfate resulted in addition of low 34s sulfide 15 to 43 and formation of higher sulfur assemblages that include valleriite and pyrite the high so4 total s ratio of hess deep serpentinites 0 89 results in an increase of total sulfur and high 34s of total sulfur mean 8 in contrast iberian margin serpentinites gained large amounts of 34s poor sulfide mean total s 3800 ppm and the high sulfide total s ratio 0 61 results in a net decrease in 34s of total sulfur mean 5 thus serpentinization is a net sink for seawater sulfur but the amount fixed and its isotopic composition vary significantly serpentinization may result in uptake of 0 4 14 1012 g s yr 1 from the oceans comparable to isotopic exchange in mafic rocks of seafloor hydrothermal systems and approaching global fluxes of riverine sulfate input and sedimentary sulfide output

effects of magmatic processes serpentinization and talc carbonate alteration on sulfide mineralogy and ore textures in the black swan disseminated nickel sulfide deposit yilgarn craton the black swan disseminated orebody occurs predominantly within the partially carbonated serpentinite core of a zoned serpentinite talc carbonate ultramafic cumulate body of komatiitic parentage the black swan disseminated sulfides depart significantly from the characteristic pattern observed in otherwise similar deposits in western australia and canada which display magnetite bearing pentlandite rich sulfide aggregates blebs in serpentinites and s rich millerite bearing assemblages in talc carbonates the black swan disseminated ores in contrast are dominated by millerite pyrite polydymite assemblages in both serpentinites and talc carbonates with no evident relationship to the progression of carbonation sulfides show three types of intergrowth with gangue minerals which can occur separately or all together intergrowth with magnetite at least some of which appear to be primary magmatic in origin fine intergrowth with interlocking lath textured antigorite and intergrowth with carbonate minerals carbonate commonly replaces the core of sulfide blebs while retaining the primary magmatic outline carbonate replacement of sulfide roughly parallels the overall progression of carbonation of the whole rock but no systematic relationship of the other intergrowth types to carbonate content is observed in the serpentinites serpentine mineralogy determined by microbeam raman spectroscopy comprises lizardite which occurs in pseudomorphic mesh textures after olivine and antigorite formed by variable degrees of overprinting of original lizardite mesh textures ranging to a completely overprinting interlocking texture with no relic igneous texture this progression is interpreted as the result of mild thermal metamorphism of original lizardite serpentinite this progression is completely independent of carbonate content and is also apparently independent of extent of sulfide antigorite intergrowth which is interpreted as being early and related to volume expansion during initial sea floor serpentinization talc is almost completely absent from serpentinites while carbonate content varies widely whole rock ni and s data are very strongly correlated in millerite poor pentlandite rich samples and poorly correlated in samples where millerite is the dominant ni bearing sulfide on this basis we conclude that the pentlandite assemblages are slightly modified survivors of the original magmatic event while the millerite pyrite assemblages formed during the earliest stages of serpentinization overprinting of the early serpentinization event by talc carbonate had essentially no effect on sulfide mineralogy other than inducing intergrowth with carbonate a number of distinctive features such as magnetite rich bleb cores the association of sulfides with segregation vesicles and chromite shells the subspherical morphology of the blebs and preferential replacement of bleb cores are considered to be inherited from the magmatic phase and are attributed to an original high but variable oxygen and halogen content of the sulfide melt component exsolution of this component during solidification of the blebs in some cases produced sulfide centered bubbles now preserved as segregation vesicles while in other cases oxygen was retained within the bleb forming magnetite sulfide intergrowths chromite shells formed as a result of exsolved oxygen interacting with komatiite magma volatile rich blebs solidified in some cases with hollow or porous cores which were subsequently exploited by carbonate replacement

combining amphibious geomorphology with subsurface geophysical and geological data a neotectonic study at the front of the alps bernese alps switzerland abstract in the vicinity of lake thun at the front of the bernese alps switzerland we performed a multidisciplinary neotectonic study combining onshore and offshore geological data and geophysical measurements in order to identify potentially active fault structures paleoseismic reconstructions on the northern margin of the alps have documented several strong earthquakes with moment magnitudes 6 during the late quaternary which have long recurrence intervals of 1 000 to 2 000 years such earthquakes are expected to produce surface ruptures in this light we investigated the study area located near lake thun primarily for on fault evidence to date still a shortcoming in switzerland we detected several features indicating potential fault activity such as aligned subaquatic morphological depressions offset horizons observed in reflection seismic profiles of lake sediments and in ground penetrating radar images all delineating a fault trace observations of fluvial deposits in a nearby gravel pit in the prolongation of the inferred structure supports these findings a narrow zone with rotated long axes of pebbles inclining at 60 is clearly distinguishable and crosscuts the original bedding with predominantly horizontal orientation of pebble axes this zone further shows an apparent 1 1 m offset of oxidized horizons and is therefore considered as a potential fault plane in a normal faulting regime a dated radiocarbon age of 11 000 years bp of the gravel deposits hence suggests a younger fault activity during the holocene the einigen fault zone efz proposed on the basis of these observations is considered as a complex fault system with a combination of dextral strike slip and normal faulting as suggested by gpr images observations in the gravel pit and radar data independently show that it includes at least two fault strands however while five earthquakes with epicentral intensities i 0 vi and numerous smaller seismic events are known within less than 30 km epicentral distance to lake thun over the past 400 years none of these seem to coincide with the location of the efz

the 1674 ambon tsunami extreme run up caused by an earthquake triggered landslide we present an analysis of the oldest detailed account of tsunami run up in indonesia that of the 1674 ambon tsunami rumphius in waerachtigh verhael van de schuckelijcke aerdbebinge batavia dutch east indies 1675 at 100 m this is the largest run up height ever documented in indonesia and with over 2300 fatalities even in 1674 it ranks as one of indonesia s most deadly tsunami disasters we consider the plausible sources of earthquakes near ambon that could generate a large destructive tsunami including the seram megathrust the south seram thrust and faults local to ambon we conclude that the only explanation for the extreme run up observed on the north coast of amon is a tsunami generated by an earthquake triggered coastal landslide we use a two layer tsunami model to show that a submarine landslide with an approximate volume of 1 km3 offshore the area on ambon s northern coast between seith and hila where dramatic changes in coastal landscape were observed can explain the observed tsunami run up along the coast thus the 1674 ambon tsunami adds weight to the evidence from recent tsunamis including the 1992 flores 2018 palu and sunda strait tsunamis that landslides are an important source of tsunami hazard in indonesia

unusual animal behavior before earthquakes a review of possible sensory mechanisms to determine whether reports of unusual animal behavior before earthquakes are plausible we have compared these reports with recent laboratory studies of animal sensory thresholds our major conclusion is that some animals are much more capable than humans of perceiving certain kinds of geophysical stimuli which may precede earthquakes these geophysical stimuli are seismic or acoustic waves at low frequency below 50 hz electric field changes and olfactory stimuli for example recent studies suggest that some birds and fish are more sensitive than humans to sounds with frequencies below 40 hz and many animals are exceptionally good at perceiving low frequency vibrations through their skin certain fish are sensitive to electric field changes as small as 10 5 v m and some laboratory mammals also respond to significantly weaker fields than humans for these electric and acoustic stimuli the reported levels of geophysical precursors are within the reported perceptible range of some animals which show unusual behavior prior to earthquakes in addition stimuli caused by the release of gases from small cracks may well be perceived by some animals before earthquakes recent research has confirmed the remarkable olfactory sensitivity of some animal species but no quantitative comparisons with geochemical precursors can be made yet we find no evidence that magnetic field precursors or precursory high frequency above 10 khz sounds are the cause of unusual animal behavior before earthquakes although some animals are highly sensitive to these stimuli observed magnetic precursors tend to be of low amplitude amid relatively high noise levels and high frequency sound is severely attenuated within a short distance from the earthquake hypocenter knowledge of animal sensory capabilities may suggest an instrumental strategy for detecting earthquake precursors we recommend further geophysical research in seismic areas to measure 1 seismic waves in the frequency range 10 50 hz 2 earthquake related electric field changes and air ionization and 3 coseismic or preseismic release of trapped gases other than radon further biological research can refine our understanding of 1 responses to sounds and vibrations with frequencies below 50 hz 2 the effects of electrical and electrostatic changes on animal behavior 3 behavioral responses to odors and 4 sensory capabilities of common domestic animals like horses dogs and chickens which are seldom studied but commonly mentioned in the preearthquake reports

redistribution of ore elements during serpentinization and talc carbonate alteration of some archean dunites western australia serpentinization of barren and weakly mineralized archean dunites in the yilgarn block western australia occurred without any apparent loss of major components including the important ore elements ni and fe sulfur addition during initial serpentinization resulted in about 30 percent of original silicate ni being redistributed to newly formed sulfide by reactions similar to olivine water lizardite brucite and lizardite brucite s lizardite brucite magnetite heazlewoodite water h 2 serpentinization at a higher temperature or metamorphism of the lizardite bearing assemblage formed antigorite serpentinite in which up to 60 percent of bulk rock ni is incorporated in sulfide form lizardite brucite magnetite heazlewoodite co 2 s antigorite magnesite magnetite ni sulfide water h 2 complete co 2 metasomatism resulted in talc carbonate rocks with still more ni redistributed to sulfides and the formation of some fe sulfide antigorite magnesite magnetite ni sulfide co 2 s talc magnesite pentlanditc fe sulfide or magnetite water o 2 in areas where low s activity precluded sulfide formation ni was strongly enriched in magnetite in serpentinites or talc in talc carbonate rocks preexisting disseminated ni sulfides of magmatic origin were significantly upgraded by serpentinization up to 30 percent of sulfide ni in ores averaging about 0 7 percent ni is of metamorphic origin and this proportion may be higher in talc carbonate ores fe sulfides of metamorphic origin form up to 20 percent of the total sulfide fraction in talc carbonate altered disseminated ni ores so that about half the sulfide content of these ores may be metamorphically derived by redistribution of elements originally held in olivine

the helice fault the site of the ancient greek city of helice which was destroyed by an earthquake in 373 bc has never been found we propose that it was submerged as the result of seismic slip on a normal fault traceable se of egion and that the fault was reactivated in 1881 when schmidt reported a fresh scarp 2 m high and 13 km in length at the same locality earlier movements on the fault are inferred from lithophaga borings on coastal sectors of the footwall which yield 14c ages representing over 6 5 m of uplift in the last 4880 years

liquefaction ground fissures and coastline change during the egio earthquake 15 june 1995 central western greece the destructive earthquake ms 6 1 r that hit the town of egio and the surrounding area of the northern peloponnessos greece generated extensive liquefaction ground fissuring and coastline changes historical data indicate that the same region has experienced episodic earthquake damage with some seismogenic phenomena having reoccurred at the same locations in conclusion it is confirmed that this is a high seismic risk region where proper building design and planning can reduce the potential danger if the geodynamic setting is properly taken into account

hydrocarbon leakage through focused fluid flow systems in continental margins transport of liquid and gaseous hydrocarbons through focused fluid flow systems is a widespread process in continental margins and sedimentary basins which is gaining increased attention in the assessment of geohazards environment conservation and securing fossil energy resources studying the abundance distribution and drivers for this process is crucial for understanding its role in 1 the dynamics of gas hydrate accumulation and destabilization 2 submarine slope stability and related tsunamis 3 the plethora of chemosynthetic benthic ecosystems that develop in deep seep sites and 4 the input of greenhouse gases e g methane into the ocean atmosphere system which may influence the atmospheric carbon budget and earth s paleo and present climate new ocean exploration tools provide ever more data and improve our understanding of these systems however the subject still suffers from a lack of interdisciplinary knowledge dissemination the ongoing international debate about the timing and the processes that control fluid expulsion in sedimentary basins is fuelled by their implications for structural and petroleum geology because fluids expelled at cold seeps originate at depth they represent open windows into the underlying petroleum systems and are valuable indicators for the reservoir systems they may also help in deciphering past and predicting future climate change because worldwide release of large amounts of fluids may have an impact on the chemistry of the ocean and atmosphere

geochemical precursors to seismic activity studies of earthquake precursory phenomena during the last several decades have found that significant geophysical and geochemical changes can occur prior to intermediate and large earthquakes among the more intensely investigated geochemical phenomena have been 1 changes in the concentrations of dissolved ions and gases in groundwaters and 2 variations in the concentrations of crustal and mantle volatiles in ground gases the concentration changes have typically showed no conanomalies trend either increasing or decreasing and the spatial and temporal distribution of the observed anomalies have been highly variable as a result there is little agreement on the physical or chemical processes responsible for the observed anomalies mechanisms proposed to account for precursory groundwater anomalies include ultrasonic vibration pressure sensitive solubility pore volume collapse fracture induced increases in reactive surfaces and aquifer breaching fluid mixing precursory changes in soil gas composition have been suggested to result from pore volume collapse micro fracture induced exposure of fresh reactive silicate surfaces and breaching of buried gas rich horizons an analysis of the available field and laboratory data suggests that the aquifer breaching fluid mixing ab fm model can best account for many of the reported changes in temperature dissolved ion and dissolved gas concentrations in groundwater ultrasonic vibration and pressure sensitive solubility models cannot reasonably account for the geochemical variations observed and although the pore collapse model could explain some of the observed chemical changes in groundwater and ground gas uncertainties remain regarding its ability to generate anomalies of the magnitude observed other geochemical anomalies in particular those associated with hydrogen and radon seem best accounted for by increases in reactive surface areas irsa model that may accompany precursory deformation around the epicenter of an impending earthquake analysis of the probable response of these models to the earthquake preparation process as well as to other environmental factors suggests that geochemical monitoring programs can provide information that may be valuable in forecasting the probability of an earthquake however because of the complexity of the earthquake preparation process the absolute prediction of seismic events using geochemical methods alone does not presently appear to be feasible

hydrothermal formation of clay carbonate alteration assemblages in the nili fossae region of mars abstract the compact reconnaissance imaging spectrometer for mars crism has returned observations of the nili fossae region indicating the presence of mg carbonate in small

seafloor facies related to upward methane flux within a giant pockmark of the lower congo basin the origin of the cold fluid venting from a giant pockmark within the lower congo basin has been elucidated based upon results of precise mapping submersible dives gravity coring and isotopic analyses realized under a total ifremer cooperative project zaiango and biozaire projects during four dives of the ifremer rov victor 6000 the bottom was filmed hard and soft samples were lifted from the sediment and water samples were collected with a ctd rosette system the detailed dip map shows that the 800 m wide giant pockmark is a composite feature due to the coalescence of multiple 100 m wide depressions that displays a broad range of biological mineralogical and chemical features on the seafloor leading to a seafloor anomaly recorded on the multibeam imagery methane rich fluids migrating through the sedimentary column from a buried palaeochannel clearly react with the sulphate rich circulating sea water to produce hydrogen sulphide and bicarbonate ions this situation leads to a concentrical arrangement of the sedimentary facies with methane related features in the centre and sulphide related features at the periphery this organization is correlated with high levels of methane up to 20 mol l measured in the centre of the giant pockmark responsible for the crystallization of gas hydrates at the bottom in this model the concentrical organization of mineralogical and biological features reflects a geochemical partitioning related to the peripheral progressive mixing of the methane flux

ritter island volcano lateral collapse and the tsunami of 1888 summary in the early morning of 1888 march 13 roughly 5 km 3 of ritter island volcano fell violently into the sea northeast of new guinea this event the largest lateral collapse of an island volcano to be recorded in historical time flung devastating tsunami tens of metres high on to adjacent shores several hundred kilometres away observers on new guinea chronicled 3 min period waves up to 8 m high that lasted for as long as 3 h these accounts represent the best available first hand information on tsunami generated by a major volcano lateral collapse in this article we simulate the ritter island landslide as constrained by a 1985 sonar survey of its debris field and compare predicted tsunami with historical observations the best agreement occurs for landslides travelling at 40 m s 1 but velocities up to 80 m s 1 cannot be excluded the ritter island debris dropped little more than 800 m vertically and moved slowly compared with landslides that descend into deeper water basal friction block models predict that slides with shorter falls should attain lower peak velocities and that 40 ms 1 is perfectly compatible with the geometry and runout extent of the ritter island landslide the consensus between theory and observation for the ritter island waves increases our confidence in the existence of mega tsunami produced by oceanic volcano collapses two to three orders of magnitude larger in scale

source discriminants for near field tsunamis summary we present numerical simulations of tsunami run up in the near field for a data set of 72 models of sources involving both seismic dislocations and landslides by varying one by one the parameters describing the source and the receiving beach we are able to separate their individual influence on the amplitude and distribution of run up which we characterize by forming several dimensionless parameters principally the ratio i 2 of its maximum amplitude to its lateral extent along the beach we find that i 2 remains less than 10 4 for seismic dislocation sources but is greater than this threshold for all physically realistic models of underwater landslides thus it can be used as a discriminant for the nature of the source of a near field tsunami for seismic dislocations we also consider the ratio i 1 of maximum run up to seismic slip on the fault plane and validate numerically the previously suggested rule of thumb that this ratio cannot be much greater than 1 in the case of underwater landslides we show that the distribution of near field run up is primarily controlled by the 2 d wall of water displaced on the ocean surface as an initial condition to the simulation and is practically independent of its extension in the third dimension perpendicular to the beach we apply this approach to nine profiles of tsunami run up obtained experimentally during recent field surveys and show that our method successfully identifies the 1998 papua new guinea tsunami as having been generated by an underwater landslide thus confirming the results of shipboard and hydroacoustic investigations it also strongly suggests a similar mechanism for the generation of the near field aleutian tsunami of 1946 april 1

the 1998 papua new guinea earthquake and its fault plane estimated from relocated aftershocks the 1998 papua new guinea earthquake of m w 7 0 occurred near the wewak trench where the north bismarck plate is subducting beneath the australian plate its mechanism is thrust type and one of the nodal planes is almost parallel to the plate interface to determine which of the two nodal planes of the main shock is the fault plane we relocated the main shock and aftershocks using a method of modified joint hypocenter determination we combined and employed two types of data in this study firstly we used data reported by the national earthquake information center neic of the u s geological survey usgs which includes three stations at the northeastern edge of irian jaya and one station in northern papua new guinea from which the epicentral distances are less than 2 degrees secondly in addition to the above permanent station data we used data from temporary aftershock observations near the epicentral area around the sissano lagoon carried out by tsuji et al 1998 using three component seismometers they carried out observations from august 2 to october 2 1998 at three sites although the network did not record the main shock and immediate aftershocks the data obtained by temporary observation sites can clearly assist in identifying their absolute locations since it is possible to apply the joint hypocenter determination jhd method hypocenters were relocated between the coastline and the wewak trench distributed along a nodal plane dipping shallowly to the southwest therefore we can conclude that this nodal plane is the main shock fault and that the 1998 papua new guinea earthquake was an interplate earthquake between the north bismarck and australian plates

fracture development and mechanical stratigraphy of austin chalk texas the mechanical stratigraphy of the upper cretaceous austin chalk is established from study of fracture intensity along its outcrop trend from dallas to san antonio and westward to langtry texas and in the subsurface from study of cores and or fracture identification logs from 30 wells three mechanical stratigraphic units are recognized 1 an upper fractured massive chalk corresponding to the big house chalk member 2 a middle ductile chalk marl corresponding to the dessau chalk and burditt marl members and 3 a lower fractured massive chalk corresponding to the atco chalk member representative samples from the three mechanical stratigraphic units were experimentally shortened dry at 10 17 34 and 70 mpa confining pressure at 24 c and at a strain rate of 2 5 10 4 sec 1 to determine if the relative mechanical behavior observed at the surface could be extrapolated into the subsurface at different simulated burial depths the experimentally determined ductilities parallel those determined from outcrop and subsurface studies multiple linear regression analysis indicates that porosity is most strongly correlated with fracture strength smectite content has the second strongest correlation for low porosity specimens 9 13 5 the strength of specimens with 4 smectite is reduced 30 42 compared to specimens with no smectite the coefficient of internal friction at 17 mpa confining pressure decreases from 1 66 to 0 61 as smectite content increases from 0 to 4 sem photomicrographs of undeformed specimens show that smectite and other clays are distributed as large 30 m discrete amorphous concentrated masses throughout the chalk they are comminuted along the induced fracture surfaces where their grain size is 0 5 m or less these observations suggest that smectite acts as a soft inclusion localizing shear failure and correspondingly weakening the material

a re appraisal of the epoch nickel sulphide deposit filabusi greenstone belt zimbabwe a hydrothermal nickel mineral system abstract the neoarchaean epoch nickel sulphide nis deposit discovered in 1970 and subsequently mined from 1972 to 1998 has been previously interpreted to be a magmatic ore system however on the basis of field petrographic and analytical data obtained during the initial exploration and evaluation stages integrated with limited new analytical data sem and ore microscopy we propose that the epoch nis may be of hydrothermal origin key features that have prompted a re appraisal of the genesis of the epoch mineralisation include a ore lenses are irregularly distributed along foliation fabrics of the host talc carbonate rocks and as such no relationship to basal ultramafic mafic units b the thickness of the ore lenses are highly variable from tens of centimetres to several metres c ore mineralogy is characterised by dominant millerite pyrite chalcopyrite assemblages and d high pd pt ratios although our hydrothermal model is somewhat speculative we suggest that on present evidence there is little doubt that the epoch nis lacks the features of typical magmatic sulphide deposits more geochemical and isotopic data are needed to test our model

societal need for improved understanding of climate change anthropogenic impacts and geo hazard warning drive development of ocean observatories in european seas society s needs for a network of in situ ocean observing systems cross many areas of earth and marine science here we review the science themes that benefit from data supplied from ocean observatories understanding from existing studies is fragmented to the extent that it lacks the coherent long term monitoring needed to address questions at the scales essential to understand climate change and improve geo hazard early warning data sets from the deep sea are particularly rare with long term data available from only a few locations worldwide these science areas have impacts on societal health and well being and our awareness of ocean function in a shifting climate substantial efforts are underway to realise a network of open ocean observatories around european seas that will operate over multiple decades some systems are already collecting high resolution data from surface water column seafloor and sub seafloor sensors linked to shore by satellite or cable connection in real or near real time along with samples and other data collected in a delayed mode we expect that such observatories will contribute to answering major ocean science questions including how can monitoring of factors such as seismic activity pore fluid chemistry and pressure and gas hydrate stability improve seismic slope failure and tsunami warning what aspects of physical oceanography biogeochemical cycling and ecosystems will be most sensitive to climatic and anthropogenic change what are natural versus anthropogenic changes most fundamentally how are marine processes that occur at differing scales related the development of ocean observatories provides a substantial opportunity for ocean science to evolve in europe here we also describe some basic attributes of network design observatory networks provide the means to coordinate and integrate the collection of standardised data capable of bridging measurement scales across a dispersed area in european seas adding needed certainty to estimates of future oceanic conditions observatory data can be analysed along with other data such as those from satellites drifting floats autonomous underwater vehicles model analysis and the known distribution and abundances of marine fauna in order to address some of the questions posed above standardised methods for information management are also becoming established to ensure better accessibility and traceability of these data sets and ultimately to increase their use for societal benefit the connection of ocean observatory effort into larger frameworks including the global earth observation system of systems geoss and the global monitoring of environment and security gmes is integral to its success it is in a greater integrated framework that the full potential of the component systems will be realised highlights societies increasingly depend on timely information on ecosystems and natural hazards data is needed to improve climate related uncertainty and geo hazard early warning observatory networks coordinate and integrate the collection of standardised data ocean observatories provide opportunity for ocean science to evolve

platinum group element and nickel sulphide ore tenors of the mount keith nickel deposit yilgarn craton australia a set of platinum group element pge analyses of about 120 samples from a 250 m continuous drill core through the mount keith komatiite hosted nickel orebody combined with ni cu co s and major elements reveals a complex trend of covariance between the original cumulus components of a thick sequence of nearly pure olivine sulphide liquid adcumulates the intersection is divided into informal chemostratigraphic zones defined primarily by combinations of fine scale cyclicity in original olivine composition defined by mg and sulphide composition defined by pt s and ni s contents of ni and pge in 100 sulphides tenors were determined from linear regressions of the ni s and pge s covariance for each zone inferred olivine compositions range from about fo92 to fo94 6 and show a broad decrease from bottom to top of the sequence complicated by numerous reversals revealing crystallisation in an open conduit system ni and pge tenors of mount keith sulphide ores have typical values similar to the type i deposits of the kambalda dome mobility of s at least on the scale of 2 m sample composites is evidently relatively minor tenors for the various zones range 12 22 ni 370 1540 ppb pt 970 3670 ppb pd 100 460 ppb ir 170 460 ppb rh and 710 1260 ppb ru pt pd and rh tenors are very strongly correlated but the iridium group of platinum group elements ipges ir and ru less so tenor variations are predominantly controlled by variations in magma sulphide ratio r 100 350 with a minor component of variance from equilibrium crystallisation trends in the parent magma pge depletion in the silicate melt due to sulphide liquid extraction is limited by entrainment of sulphide liquid droplets and continuous equilibration with the transporting silicate magma ratios of the pges to one another are similar to those in the host komatiite magma with the exception of pt which is systematically depleted in ores relative to rh and pd and relative to host magma by a consistent factor of about 2 to 2 5 this anomalous pt depletion relative to pge element ratios in unmineralized komatiitic rocks matches that observed in bulk compositions of many komatiite hosted orebodies the highly consistent nature of this depletion and particularly the very strong correlation between pt pd and rh in the mount keith deposit argue that this depletion is a primary magmatic signal and not an artefact of alteration differential diffusion rates between pt and the other pges giving rise to a low effective partition coefficient for pt into sulphide liquid is advanced as a possible but not definitive explanation

komatiites and nickel sulfide ores of the black swan area yilgarn craton western australia 2 geology and genesis of the orebodies the black swan ultramafic succession hosts a number of magmatic fe ni cu pge sulfide ore shoots ranging from high grade massive ore to low grade disseminated sulfides of these the most economically significant is the silver swan massive sulfide orebody associated with the basal contact of the succession the deposit varies in thickness between 5 and 20 m reaches a n s strike length of 75 m extends for at least 1 2 km of vertical plunge and is open at depth overlying matrix net textured ore is rare inclusions of dacite are abundant within the lower 5 m of the massive sulfide they range from angular fragments through smooth sinuous and plumose morphologies to fine lace like intergrowths with the sulfide matrix and comprise variable proportions of cores of porphyritic dacite and carapaces with skeletal plagioclase phenocrysts dynamic crystallisation and kinetic melting textures in the carapaces indicate that the inclusions have been heated to various temperatures some well above their liquidus temperature the composition of the inclusions ranges from a perfect match with the immediate footwall dacites to mixtures of dacite with up to 30 komatiite the consistent thickness of the inclusion bearing basal layer within the massive sulphide is interpreted as the extent of 3 d physical connectivity between the inclusions and a partially molten underlying hybrid layer primary contacts between the silver swan massive sulfide orebody and overlying ultramafic rocks are marked by thin rinds containing coarse grained chevron textured chromites with skeletal textures compositions of these chromites match those from kambalda perseverance and other localities and are inconsistent with a metamorphic origin they are interpreted as markers of primary magmatic contacts the combination of this feature with the general paucity of matrix ore implies that the massive ore accumulated and solidified before the accumulation of the overlying thick sequence of olivine cumulates taken together with observations on the internal fractionation of platinum group elements within the massive ores these observations are consistent with a model where the massive ore were emplaced at the floor of a small partially drained lava tube the floor of the tube had been previously heated by passage of large volumes of lava such that it had reached its melting range the felsic inclusions within the ore are the result of buoyant ascent of partially molten substrate into the ore magma this constitutes strong evidence for the operation of thermo mechanical erosion during ore emplacement the disseminated cygnet and black swan orebodies show a number of distinctive features cygnet contains a assemblage of clasts and inclusions which are interpreted as the result of rip up transport and redeposition of sulfides from a pre existing massive sulfide orebody of which black duck may be a remnant the black swan orebody by contrast does not show xenolithic features but is characterised by an association of sulfide blebs with segregation vesicles and by unusually coarse grained olivine the black swan orebody is interpreted as the result of transport of sulfide droplets within a lava charged with a suspended load of coarse olivine crystals

submarine and coastal sediment failure triggered by the 1995 ms 6 1 r aegion earthquake gulf of corinth greece on june 15th 1995 a locally destructive earthquake of magnitude ms 6 1 on the richter scale occurred offshore 7 5 km nne of the town of aegion in the western gulf of corinth greece an offshore survey using 3 5 khz subbottom profiling system and a remote operated vehicle rov has shown that the earthquake caused small sized subaerial to submarine sediment failure in at least four sites in three fan delta deposits the rododafni the eliki and the tolofonas the fan deltas were located within a radius of about 9 km from the epicentre the areal size of the four sediment failure sites ranged from 2 104 m2 to 6 105 m2 whilst the volume of the failed masses ranged from 4 103 to 3 106 m3 the sediment deformation types identified at the failure sites consist of ground cracking rotational slides elongated slides sediment gravity flows and extrusion of mixtures of water and sand sand boils the sediment failure in the four sites affected the upper 5 6 m of well layered holocene topset and foreset fan delta deposits the failure occurred on slopes ranging from 0 2 to 23 and the slip planes were all bedding planes which have a gradient from 0 2 to 21 the dominant instability mechanism that caused the sediment failure in the rododafni and eliki fan deltas is considered to be liquefaction of a shallow sub surface horizon the liquefaction was caused by elevated pore pressure enhanced perhaps by the presence of gas resulting from the cyclic loading induced by the earthquake the liquefied layer is assumed to have temporarily provided a failure surface for sliding to take place on and caused movement of sand that was ejected onto the surface in the tolofonas fan delta the causative mechanism in the case of the multi block rotational slide is considered to be deformation of the underlying sediments caused by remoulding and or liquefaction while in the case of the elongated slide it is considered to be the result of a combination of shear stress increase and or strength degradation of the unconsolidated sediment both of these conditions could have been generated during the cyclic loading resulting from the aegion earthquake the study of historical documents reveals that sediment failure like those described above have also occurred at least four times during the past 2500 years in the same locations therefore it is suggested that they could be repeated in the future by any earthquake event with a magnitude greater than 6 r depending upon the proximity of the site to the earthquake epicentre

native metals and intermetallic compounds in subduction related ultramafic rocks from the stanovoy mobile belt russian far east implications for redox heterogeneity in subduction zones abstract plutonic associations in orogenic belts are potent indicators of multi stage fractionation of primitive arc magmas and growth of island arc crust under evolving redox conditions in ancient subduction zones ildeus lucha ultramafic mafic complex ilc was emplaced at 232 233 ma within the mesozoic stanovoy convergent margin and subsequently underwent multi stage hydrothermal alteration and greenschist to amphibolite facies metamorphism 140 ma followed by adakite and k lamprophyre magmatism 114 117 ma dunite wehrlite pyroxenite and gabbro in the ilc are composed of olivine clinopyroxene orthopyroxene plagioclase and late magmatic amphibole mineral compositions in the ilc are typical of island arc plutonic complexes characterized by early crystallization of orthopyroxene plagioclase intercumulus and presence of magmatic amphibole ultramafic mafic rocks display high field strength hfs element depletions coupled with large ion lithophile lil element enrichments indicating formation via crystal fractionation of mafic primary magma derived from a subduction related mantle source some ultramafic rocks from the ilc contain native metals w pt au ag zn bi and intermetallic compounds cu au ag pt rh pd cu sn zn etc included in silicate minerals or observed as discrete phases in the finer grained silicate oxide sulfide matrix textural evidence and association with either primary magmatic or secondary metasomatic or metamorphic mineral phases suggest either magmatic high temperature or metasomatic low temperature origin of metals and metallic compounds the following models of their formation can be proposed on the basis of the presented data a crystallization w and possibly pt from metal rich arc magmas under unusually reduced conditions in subduction related lithosphere b formation from magmatic sulfides during pervasive serpentinization and release of abiogenic hydrocarbons and c precipitation from chlorine rich saline aqueous fluids associated with collision related metasomatism of the stanovoy island arc crust

the aitape 1998 tsunami reconstructing the event from interviews and field mapping on the evening of 17 july 1998 on the aitape coast of papua new guinea a strongly felt earthquake was followed some 10 25 minutes later by a destructive tsunami the tsunami comprised three waves each estimated to be about 4 m high the second of the three waves rose to a height of 10 15 m above sea level after it had crossed the shoreline and caused most damage maximum wave heights and the greatest damage were recorded along a 14 km sector of coast centered on sissano lagoon in this sector the wavefronts moved from east to west along the coast all structures were destroyed and in the two main villages 20 40 percent of the population was killed partial destruction extended 23 km to the southeast and 8 km to the northwest and effects of the tsunami were felt as far as 250 km to the west northwest beyond the international border more than 1600 people are known to have died with some estimates as high as 2200 1000 were seriously injured and 10 000 survivors were displaced this paper presents information from interviews with eye witnesses and from mapping of damage and inundation and includes new information on the height shape and timing of the waves on the possible escape of petroleum and other gases from beneath the seafloor before and during the tsunami on unusual sound effects that preceded the waves and lighting effects that followed on possible deep circulation to 250 m of sea water in the waves on subsidence of the order of 50 70 cm at the coastal sand barrier and on the resilience and potential protective capacity of certain species of trees eye witness accounts indicate that the tsunami reached the shore at between 09 00 and 09 08 ut which is earlier than is proposed in published models of the timing and location of the source of the tsunami

volcano collapse and tsunami generation in the bismarck volcanic arc papua new guinea during a cruise on the r v kilo moana in 2004 we mapped 12 debris avalanches from volcanoes in the bismarck volcanic arc estimated their sizes and computed the size of potential tsunami run up in major local population centers from these features we used the towed side scan instrument hawaii mr1 the hull mounted em120 system for swath bathymetry and backscatter intensity a shallow penetration chirp system several bottom camera tows and selected cores we calibrate our computations with the known tsunami run up of the ritter collapse even the small collapses may have had significant run up on near by coastlines had any of the collapses we have identified occurred in modern times each would affect a presently populated region of the coastline to a moderate or significant degree

comparison of archean dunites and komatiites associated with nickel mineralisation in western australia implications for dunite genesis the two important classes of archean fe ni cu sulphide deposits in western australia are those hosted by 1 coarse grained adcumulate dunites e g agnew mount keith and 2 komatiitic lavas e g kambalda close similarities in compositions of relict olivine pyroxene and chromite from dunitic and komatiitic host rocks and compositional and textural similarities between chilled margins of some dunites and some komatiites indicate origins from similar komatiitic liquids which contained 20 32 mgo as field relations suggest that the dunites are probably lateral stratigraphic equivalents of spinifextextured komatiites they are interpreted as the slowcooled end member of a continuum from spinifex textured komatiites former liquids through cumulate komatiites 40 90 olivine to adcumulate komatiitic dunite 90 olivine previous classification of these ni deposits as intrusive and volcanic related deposits now appears unwarranted and the terms komatiitic dunite hosted and komatiite hosted deposits are preferred

alternating marine and lacustrine sedimentation during late quaternary in the gulf of corinth rift basin central greece abstract the gulf of corinth in central greece has a maximum depth of about 900 m and is separated from the open sea by the rion strait with a sill depth of 62 m marked by an extensive submarine terrace during eustatic sea level lowstands the gulf of corinth was a lake under lacustrine conditions stratified sediments accumulated in the deep water basins and turbid underflows from rivers eroded the basin slopes as the sea level rose marine waters flooded the gulf and deltas prograded across the shelves in shallow water areas two key reflectors termed z and x are terrace surfaces commonly erosional which mark the base of the overlying deltaic sequences in deep water basins z and x mark the top of the acoustically stratified sediments interpreted as lacustrine turbidites reflectors y and w mark the base of these stratified intervals and overlie acoustically transparent sections similar to the holocene section the last lacustrine conditions in the gulf z to y were during isotopic stage 2 and terminated about 12 000 yr ago age estimates based on sedimentation rates suggest that the x to w interval corresponds to the stage 4 lowstand of sea level in the western gulf of corinth shoreline transgressive surfaces corresponding to minor transgressions in stage 5 and to major transgression at the end of stage 6 are recognised this seismic stratigraphy permits a detailed interpretation of the history of the gulf of corinth in the past hundred thousand years it also provides a general model for sedimentation in rift basins in which marine and lacustrine sediments alternate

implications of structural segmentation during earthquakes the 1995 egion earthquake gulf of corinth greece the egion earthquake which occurred in the gulf of corinth central greece ms 6 2 on 15 june 1995 was caused by normal slip on the north dipping and wnw trending egion fault the egion fault ruptured at depth during the egion mainshock and probably re ruptured at shallow level during the largest aftershock the surface trace of the egion fault has a segmented geometry linkage between three segments which show long term deformation differences as well as coseismic segmentation enabled all segments to be incorporated in an earthquake segment the surface ruptures continued to grow after the coseismic motion the afterslip throw of the fault 10 weeks after the main event was equal to the 3 cm value for maximum coseismic slip this afterslip was accompanied by uplift of the footwall block and a warp like hangingwall subsidence folding this pattern of deformation was associated with more complex deformation at the western end of the earthquake segment here afterslip was accompanied by general subsidence of the whole area between 25th june and 30th july followed by uplift of the whole area without afterslip between 30th july and 2nd september the afterslip rate averaged over the 73 day period after the main event varied from 0 48 mm day 1 along the central part of the earthquake segment to 0 16 mm day 1 at the eastern end of the earthquake segment

active pockmarks in a large lake lake constance germany effects on methane distribution and turnover in the sediment in the eastern part of lake constance the second largest prealpine lake in europe about 500 pockmarks morphological depressions on the lake floor were recently discovered the diameters of these pockmarks are as large as 16 m and about 24 of them continuously release methane in the form of visible bubbles the isotopic composition of the escaping gas indicated that the methane was of biogenic origin and was predominantly produced by the co2 reduction pathway in shallow water pockmarks 9 m and 12 m pore water analysis revealed increased methane concentrations of 1100 mol l 1 in the sediment diffusive methane fluxes and oxidation rates within these shallow pockmarks were much higher than in sediments outside pockmarks an estimated methane ebullition into the water column of about 40 l h 1 per pockmark showed that methane ebullition is by far the dominant pathway of methane release from these shallow pockmarks meiofauna abundance and organic carbon contents of the sediment were also higher in the shallow pockmarks but there were no differences in macrofauna in a deep pockmark 80 m even though bubble release was observed the sediment inside the pockmark had almost the same methane concentrations and isotopic compositions as a site outside of the pockmark at both sites the shallow and deep pockmark act mainly as sedimentation traps the emanating gas has only minor influence on the methane inventory of the sediments and therefore gas bubbles enter the water column essentially unaffected

a seismological study of the eastern new guinea and the western solomon sea regions and its tectonic implications summary we use new and pre existing seismological data to study the neotectonics and the state of stress in the seismic zones of eastern papua new guinea and the western solomon sea regions earthquake hypocentres for the period 1964 90 were relocated using the joint hypocentre determination jhd technique we show that the t axes of earthquakes in the 100 250km depth range beneath eastern papua new guinea are aligned parallel to the seismic zone with no seismicity below 250 km this intermediate depth seismic zone forms an inverted u shaped zone with limbs dipping to the north and south and is interpreted to be seismicity along the subducted solomon sea plate the northern and southern limbs of the seismic zone are connected by a flattened zone of seismicity which is marked by predominantly strike slip and a few normal fault mechanisms we suggest that the solomon sea plate at depth beneath the finisterre mountains is no longer influenced by the tectonic forces acting at the surface but breaking up and sinking under its own gravitational forces a significant north dipping seismic zone is imaged above the deeper seismic zone this feature characterized by thrust mechanisms extrapolates to the surface along the ramu markham valley and is attributed to the ramu markham fault rmf the rmf has an average dip of about 40 to the north east but its detailed geometry would appear to be complex the rmf is interpreted to ramp steeply in the uppermost 10 20 km flattening out sharply to a dip of 15 at a depth of about 20km the rmf marks the suture between the finisterre terrane and the australia new guinea plate and may extend to a depth of 90km beneath the western limit of the finisterre mountains there is a clear gap in seismicity between the rmf and the deeper solomon sea plate seismic zone beneath the finisterre mountains which together with the alignment of the t axes of earthquakes along the seismic zone at depths 100km indicates that these are indeed two distinct features the seismicity in the depth range 50 80 km along the new britain arc follows the trend of the 2000m bathymetric contour of the new britain trench and the finsch deep far more closely than it does the trend of the surface plate boundary indicating that the increase in the distance between the solomon sea south bismarck plate boundary and the active volcanos along the new britain arc west of 6 83 150 o e is only a shallow phenomenon and does not reflect the geometry of the solomon sea plate at depths greater than 50 km

late holocene evolution of the east eliki fault gulf of corinth central greece abstract trench stratigraphy and morphotectonic analysis was used to examine the recent evolution of the helike eliki plain and eliki fault the entire alluvial plain of the kerynites and vouraikos rivers which cross the eliki fault has subsided at rate of 1 4 mm yr resulting in the burial of the late hellenistic roman occupation horizons under 3 m of fluvial and colluvial sediments along the eastern segment of the eliki fault five trenches have been excavated and their 5000 yr old fluvial and colluvial deposits have been studied in association with the fault strand imprinted on them the kerynites river crosses at high angle the eliki fault and appears to be sensitive in tectonic movements related with the eliki fault sedimentation in the alluvial plain and the fluvial geomorphology of the kerynites river is important for understanding the fault evolution and the burial of the ancient 4th century bc helike city the kerynites river course highlights breaching deformation is the more likely to connect east and west eliki fault segments and that postseismic deformation is a significant mechanism for stress accommodation for part of the west end of the gulf of corinth

petrography mineralogy and geochemistry of the nkamouna serpentinite implications for the formation of the cobalt manganese laterite deposit southeast cameroon the nkamouna co mn ni laterite is an advanced exploration project located in southeast cameroon the deposit comprises a deep and complex laterite profile with high co 0 25 wt and mn 1 33 wt contents subeconomic ni grade and a ni co ratio of less than 3 this makes nkamouna an unusual type of laterite deposit as it will be primarily mined for co the co mn mineralization occurs at the interface between an overlying allochthonous felsic rock sourced laterite and a lower in situ serpentinite derived laterite the serpentinite is massive with a nonpseudomorphic texture and consists of two genetically related phases serpentinite i and serpentinite ii serpentinite i is characterized by antigorite magnetite quartz ferritchromite and magnesite and serpentinite ii by antigorite and magnesite both serpentinite types are extremely low in sulfides serpentinite i is the dominant and oldest phase and was derived from a subcontinental mantle pyroxene rich peridotite emplaced in the crust during the pan african orogeny the ni concentration in the serpentinite is variable 0 07 0 30 and heterogeneously distributed partly reflecting the present dominance of pyroxenes in the protolith however ni is also hosted by magnetite and ferritchromite the differential weathering of these ni hosting minerals is also responsible for the lower ni grade of the deposit importantly the serpentinite is depleted in co and mn and the enrichment of these elements in the laterite profile suggests that these elements may be derived from an exotic source

chromite in komatiites ii modification during greenschist to mid amphibolite facies metamorphism chromite compositions in komatiites are influenced by metamorphic chromite is highly susceptible to modification during processes particularly above 500 c metamorphosed chromite is early hydrous alteration and subsequent prograde metasubstantially more iron rich than igneous precursors as a result of morphism of host rocks this modification is the subject mg fe exchange with silicates and carbonates chromite metaof this paper morphosed to amphibolite facies is enriched in zn and fe and metamorphic modification of chromite has been disdepleted in ni relative to lower metamorphic grades relative cussed extensively in the literature in the context mainly of proportions of the trivalent ions cr al and fe are not ophiolitic or alpine ultramafic complexes onyeagocha greatly modified by metamorphism up to lower amphibolite facies 1974 ulmer 1974 evans frost 1975 hoffman although minor fe depletion occurs during talc carbonate alwalker 1978 loferski lipin 1983 kimball 1990 teration at low temperature significant al is lost from chromite burkhard 1993 and in a few studies of komatiitic rocks cores above 550 c as a result of equilibration with fluids in bliss maclean 1975 donaldson 1983 gole hill equilibrium with chlorite elevated zn content in chromite is 1990 and in a detailed study of the pechenga intrusions restricted to rocks with low metamorphic mg fe ratios and is abzalov 1998 these studies have highlighted two the result of introduction of zn during low temperature alteration important effects first chromites become rimmed and with further concentration and homogenization during prograde progressively replaced by chromian magnetite or fermetamorphism cobalt and mn also behave similarly except where ritchromit second chromite core compositions become carbonate minerals are predominant in the metamorphic assemblage progressively modified during prograde metamorphism chromite at amphibolite facies is typically extensively replaced by as a result of exchange of components with surrounding magnetite this is the result of incomplete metamorphic reaction silicate minerals evans frost 1975 abzalov 1998 between chromite and chlorite bearing silicate assemblages magthis paper examines the nature and magnitude of these netite compositions at the inner chromite magnetite boundary are effects in komatiites from a variety of localities in the indicators of metamorphic grade eastern goldfields province of the archaean yilgarn block in western australia fig 1 brief locality descriptions are given in appendix b

geodetic estimate of seismic hazard in the gulf of korinthos the recent 15 june 1995 m0 6 0 1018 n m aigion earthquake in the western gulf of korinthos has focussed attention on the seismic hazard of the region although there have been few large earthquakes in the region during this century the historical record suggests that there may have been many large earthquakes there in the interval 1750 1900 we present geodetic data that give estimates of the rate of extension of the gulf of korinthos during this century and which suggest that less than half of the elastic strain in the central and western gulf of korinthos has been released by earthquakes during this century in contrast the seismic and geodetic strains in the eastern gulf of korinthos are in agreement with each other if the discrepancy between seismic and geodetic strains in the western gulf of korinthos that has accumulated during this century is removed in earthquakes the moment release will be equivalent to several ms 6 5 earthquakes

tectonically induced anomalies without large earthquake occurrences in this study we documented a case involving large scale macroscopic anomalies in the xichang area southwestern sichuan province china from may to june of 2002 after which no major earthquake occurred during our field survey in 2002 we found that the timing of the high frequency occurrence of groundwater anomalies was in good agreement with those of animal anomalies spatially the groundwater and animal anomalies were distributed along the anninghe zemuhe fault zone furthermore the groundwater level was elevated in the northwest part of the zemuhe fault and depressed in the southeast part of the zemuhe fault zone with a border somewhere between puge and ningnan counties combined with microscopic groundwater geodetic and seismic activity data we infer that the anomalies in the xichang area were the result of increasing tectonic activity in the sichuan yunnan block in addition groundwater data may be used as a good indicator of tectonic activity this case tells us that there is no direct relationship between an earthquake and these anomalies in most cases the vast majority of the anomalies including microscopic and macroscopic anomalies are caused by tectonic activity that is these anomalies could occur under the effects of tectonic activity but they do not necessarily relate to the occurrence of earthquakes

gas geochemistry applied to earthquake prediction an overview terrestrial gases in groundwater and soil air have been extensively studied in recent years in seismically active areas especially in ussr china japan and united states in search of premonitory changes that might be useful for earthquake prediction concentrations of radon helium hydrogen mercury carbon dioxide and several other volatiles have been found generally to be anomalously high along active faults suggesting that the faults may be paths of least resistance for the terrestrial gases generated or stored in the earth to escape to the atmosphere temporal gas concentration changes with durations of a few hours to many months have been observed before many large earthquakes at a relatively small number of favorably situated stations at epicentral distances of up to several hundreds of kilometers these sensitive stations are generally located along active faults especially at intersections or bends of faults or some other structurally weak zones possibly because of tectonic strain concentration at such places however gas concentrations especially those measured at or near the ground surface may also be significantly affected by meteorological hydrological and other nontectonic changes in the environment the nontectonically induced variations must be carefully eliminated or recognized in the search of true earthquake related anomalies

hydrothermal remobilisation around a deformed and remobilised komatiite hosted ni cu pge deposit sarah s find agnew wiluna greenstone belt yilgarn craton western australia the sarah s find nickel deposit located 4 5 km north of the mount keith nickel mine western australia was chosen as a case study to investigate the nature and three dimensional geometry of a geochemical halo created by the hydrothermal remobilisation of base metals and platinum group elements into the country rock surrounding a small massive ni sulphide orebody portable and laboratory based xrf analyses were carried out on samples from a shear zone localised along the basal komatiite dacite contact that hosts the orebody a geochemical halo was identified that extends along the shear zone up to 1780 m away from the massive sulphides parallel to a prominent stretching lineation elevated ni and pd are associated with high as co cu and s palladium and pt concentrations increase with proximity to massive sulphides from 6 to 1190 ppb pd these anomalous concentrations reflect the presence of sulfarsenides and sulphides either physically remobilised and forming veinlets close to the massive sulphides or hydrothermally transported and redeposited within the foliation in situ laser ablation icp ms indicates that pd and pt are hosted within these nickel sulfarsenides this ni co as pd geochemical halo observed around the sarah s find ore body is interpreted as forming syn deformation by the circulation of as rich hydrothermal fluids dissolving base metals pd and pt from the orebody and redepositing them along the sheared footwall contact similar ni co pd pt as geochemical haloes could potentially exist around any magmatic nickel sulphide mineral system that has undergone a phase of arsenic metasomatism and may be a generally applicable proximity indicator for nickel sulphides in hydrothermally altered terranes

types of fluid related features controlled by sedimentary cycles and fault network in deepwater nigeria abstract the seismic characteristics of focused fluid related features such as pockmarks and carbonate build ups on the nigerian continental slope have been investigated using complementary seismic data sets reprocessed 3d exploration data and 2d very high resolution hull mounted and near bottom seismic data coupled with the results of previous studies sedimentological geotechnical and geochemical analyses the results show different types of fluid related features within the hemipelagic phase of long duration 1 myr turbidite hemipelagic cycles they are the product of the disturbance of the hosting sediments following two main distinct processes 1 no or low sediment deposition caused by fluid escape associated with seafloor settlement benthic fauna carbonate precipitation gas hydrate formation and 2 post depositional erosion caused either by fluid release dewatering from underlying features such as channels and upward migration from a deep source or by collapse destabilisation of gas hydrates the temporal evolution reveals a decrease in fluid flow during the hemipelagic deposition as witnessed by the decrease in methanogenic activity and by gas hydrate destabilisation the spatial distribution of fluid related features seems to be controlled by the type of fault small fault or structural lineament

the egion june 15 1995 6 2m l earthquake western greece on june 15 1995 at 00 15 gmt a devastating earthquake 6 2m l occurred in the western end of the gulf of corinth this was followed 15 min later by the largest aftershock 5 4m l the main event was located by the university of patras seismological network patnet at the northern side of the gulf of corinth graben the second event 5 4m l was located also by patnet near the city of egion on a fault parallel to the eliki major fault that defines the south bound of the gulf of corinth graben a seismogenic volume that spans the villages of akrata se and rodini nw and extends to eratini ne was defined by the aftershock sequence which includes 858 aftershocks of magnitude greater than 2m l that occurred the first seventeen days the distribution of hypocentres in cross section does not immediately suggest a planar distribution but rather defines a volume about 15 km depth by 35 km nw se and by 20 km ne sw

analysis of the far field tsunamis generated by the 1998 papua new guinea earthquake the tsunami generated by the 1998 papua new guinea earthquake was observed at several tide gauges and ocean bottom pressure gauges in japan the fault model of the 1998 papua new guinea earthquake was estimated using those tsunami waveforms observed in japan and coseismic subsidence observed along the coast of papua new guinea near the source region the numerical simulation of the tsunami using the linear boussinesq equation was carried out the tsunami waveforms in japan are explained by the fault model which is consistent with the harvard cmt solution including the seismic moment of 3 7 1019 nm the additional tsunami source such as a sediment slump is not needed to explain the observed tsunami in japan the mechanism of the earthquake was likely to be a steeply dipping reverse fault the 1998 papua new guinea earthquake was likely to occur within a small accretionary prism near the new guinea trench

macroscopic seismic anomalies and submarine pockmarks in the corinth patras rift greece prior to the aigion earthquake m 6 2 of 15 june 1995 in the western gulf of corinth people in the area observed anomalous phenomena including bubbling of the sea extraordinary behavior of animals earthquake lights ground deformation and the sound of wind immediately before the shock some precursory phenomena of this kind might be understood as symptoms of gas venting before an earthquake sonar observations made in 1988 showed a chain of submarine pockmarks tracing the aigion fault and evidently produced by the expulsion of fluids under pressure t hasiotis et al mar geol 130 333 344 reported that hot gas erupted from a field of giant submarine pockmarks in the neighboring bay of patras several hours prior to an earthquake in 1993 automated monitoring of bottom water temperature in submarine pockmark fields may detect outgassing events prior to earthquakes in this region

mechanical and fracture stratigraphy using examples from core studies this article shows that separate identification of mechanical stratigraphy and fracture stratigraphy leads to a clearer understanding of fracture patterns and more accurate prediction of fracture attributes away from the wellbore mechanical stratigraphy subdivides stratified rock into discrete mechanical units defined by properties such as tensile strength elastic stiffness brittleness and fracture mechanics properties fracture stratigraphy subdivides rock into fracture units according to extent intensity or some other observed fracture attribute mechanical stratigraphy is the by product of depositional composition and structure and chemical and mechanical changes superimposed on rock composition texture and interfaces after deposition fracture stratigraphy reflects a specific loading history and mechanical stratigraphy during failure because mechanical property changes reflect diagenesis and fractures evolve with loading history mechanical stratigraphy and fracture stratigraphy need not coincide in subsurface studies current mechanical stratigraphy is generally measurable but because of inherent limitations of sampling fracture stratigraphy is commonly incompletely known to accurately predict fractures in diagenetically and structurally complex settings we need to use evidence of loading and mechanical property history as well as current mechanical states

geophysical and geochemical analysis of shallow gas and an associated pockmark field in bantry bay co cork ireland abstract an integrated geophysical geological and geochemical investigation of seabed fluid venting was carried out in upper bantry bay a large marine inlet on the southwest coast of ireland the results provide evidence of the seafloor venting of gas rich fluids resulting in the formation of a pockmark field identified here for the first time the pockmarks occur in an area where sub bottom profiles provide evidence of chimney like features interpreted to record upward gas migration through quaternary sediments to the seafloor three vibrocores up to 6 m long were acquired in water depths of 24 34 m two from the pockmark field and one from outside methane of predominantly biogenic origin was quantified in all three cores by headspace analysis of sediment sub samples well defined sulfate methane transition zones smtzs were observed in two of the cores the shallowest 1 25 m below sea floor mbsf inside the pockmark field and the other 3 75 mbsf outside it is likely that an smtz occurs at the location of the third core also within the pockmark field although deeper than the samples obtained during this study gas migration towards the seafloor is suggested to involve both diffuse pore fluid migration across wide areas and focused flow through the pockmarks together driven by methanogenesis of pre glacial lacustrine sediments preserved in a bedrock basin and possible gas release from the owenberg river fault analysis of phospholipid fatty acids plfas and archaeal isoprenoid hydrocarbons was used to investigate the microbial ecology of these sediments anaerobic oxidation of methane aom may play a role in controlling release of ch4 to the water column and atmosphere in this shallow gas setting potentially mediated by syntrophic sulfate reducing bacteria srb and anaerobic methanotrophic archaea anme

postmagmatic variability in ore composition and mineralogy in the t4 and t5 ore shoots at the high grade flying fox ni cu pge deposit yilgarn craton western australia the high grade flying fox komatiite hosted ni sulfide deposit located in the forrestania greenstone belt of the archean yilgarn craton western australia is hosted in a deformed and metamorphosed volcano metasedimentary succession postmineralization events have sheared and modified the texture and composition of the original massive sulfide ore creating up to 11 distinct ore shoots including massive stringer vein and breccia sulfides composed of pyrrhotite pentlandite chalcopyrite and variable abundances of pyrite ranging up to 40 vol nickel and platinum group elements pge tenor variations were investigated in two ore shoots t4 and t5 all mineralization styles show considerable variability in ni tenor pges show strong linear correlations between ir os ru and rh but poor correlation between pt pd and cu the normalized molar proportions of fe ni and s projected into the fe ni s ternary system show a distinct linear trend of pyrite addition to a typical primary magmatic composition and no correlation with mineralization style the high pyrite content present throughout the flying fox ore is also associated with elevated cu and as contents and is interpreted to be primarily due to the addition of pyrite from circulating fe s cu and as enriched fluids creating pyrite pentlandite intergrowths localized mechanical segregation of pyrite sulfidation of pyrrhotite to pyrite and oxidation of pyrrhotite to pyrite magnetite has also contributed to these increased pyrite contents although to a lesser extent the addition and segregation of pyrite has diluted the ni tenor with no evidence to suggest chemical mobilization of ni

tsunami sediments and their foraminiferal assemblages abstract tsunami hazard assessment begins with a compilation of past events that have affected a specific location given the inherent limitations of historical archives the geological record has the potential to provide an independent dataset useful for establishing a richer chronologically deeper time series of past events recent geological studies of tsunami are helping to improve our understanding of the nature and character of tsunami sediments wherever possible geologists should be working to improve the research tool kit available to identify past tsunami events marine foraminifera single celled heterotrophic protists have often been reported as present within tsunami deposited sediments but in reality little information about environmental conditions and by analogy the tsunami that deposited them has been reported even though foraminifera have an enormous capacity to provide meaningful palaeo environmental data here we review what foraminifera are describe their basic form and significance summarise where they have been reported in tsunami sediments and identify what can be learnt from them we review the gaps in our understanding and make recommendations to assist researchers who examine foraminiferal assemblages in order to enhance their use within tsunami geology

geometry and kinematics of active faults and their seismotectonic significance in the western corinth patras rift greece abstract the western part of the corinth patras rift is formed in an area which is being uplifted rifted domains have subsided relative to the adjacent areas in nw peloponnesus and sterea hellas but subsidence rates rarely exceed uplift rates extension is mainly accomplished by wnw trending active faults with lengths up to 25 km most of these faults show an along strike segmentation and often terminate against transfer faults displacement analysis along 170 mesoscopic faults and 36 mappable faults has been carried out to assess slip rates and to estimate the magnitudes and recurrence time intervals of earthquakes occurring along them earthquake magnitude ranges between 5 and 6 7 only eight faults appear to be capable of producing earthquake magnitudes larger than 6 recurrence times of these large earthquakes vary between 80 and 1690 years upper crustal deformation in the western corinth graben can be described by six large asymmetric grabens which are inferred to bottom out to a n dipping curved ramp the asymmetric shape of most wnw trending rifts in the hellenic peninsula including the corinth patras rift promotes the simple shear model of extension against the pure shear model in the upper crustal layer

the aigion neos erineos coastal normal fault system western corinth gulf rift greece geomorphological signature recent earthquake history and evolution 1 at the westernmost part of the corinth rift greece an area of rapid extension and active normal faulting geomorphological observations reveal the existence and geometry of an active nw se trending coastal fault system which includes the aigion fault we recognize a similar fault pattern on both the coastal range front to the nw of aigion town and the holocene fan deltas in front of it we interpret this as a result of recent migration of faulting to the hanging wall of the fault system differences in the geomorphic expression of the constituent faults provide hints on the possible evolution of the fault pattern during this recent migration a trench excavated across one of the identified coastal fault scarps on a holocene fan delta provides information on the seismic history of the fault system which includes at least four possibly six earthquakes in the past 4000 years a minimum estimate for the slip rate of the trenched fault is 1 9 2 7 mm yr the trench exposed sediments of an uplifted paleolagoon approximate age 2000 years b p inside which the last two earthquakes formed an underwater monoclinal scarp oscillating coastal vertical movements are suggested by the fact that the lagoonal deposits are also uplifted on the trenched fault hanging wall uplift by offshore faults and by the abrupt transition from fluvial to lagoonal deposits subsidence by more landward faults assuming that extensive coastal sediment failure has not taken place in the specific part of the fan delta within the time interval of interest these movements suggest that the proposed migration of activity from the range front faults to those on the fan deltas is probably still ongoing with activity on both sets of faults

the 17 july 1998 tsunami papua new guinea evidence and initial interpretation abstract a m w 7 1 earthquake that occurred at 08 49 hours 17 july 1998 utc 6 49 pm local time off the north coast of papua new guinea generated a locally destructive tsunami more than 2189 people died and virtually no structures were left standing along 19 km of coast a fast moving wall of sand laden water left fishing nets and other detritus in trees up to 17 5 m above sea level concrete was stripped to the reinforcing metal and some trees were ripped out and carried more than a kilometre back into sissano lagoon the site is in an active sedimentary basin the aitape trough with 4500 m thickness of neogene sediments between the bewani fault zone and the wewak trench there is some debate about the form of tsunami propagation for this event however we present evidence for subsidence of 30 40 cm on the landward side of the spit fronting sissano lagoon furthermore the area may have subsided up to three times this century in situ stumps of drowned trees in the lagoon record at least one earlier event the low angle harvard university cmt solution m w 7 1 depth 6 0 km 10 landward dip on fault with northward displacement is consistent with the tectonic setting and pattern of aftershocks elastic modelling of the energy release suggests 2 m horizontal displacement over 600 km 2 40 cm subsidence landward and 60 cm uplift seaward convergent flow of the displaced water into the area of subsidence focused wave energy on the coast and generated the locally high wave the record of tsunami at sissano lagoon indicates that the spit fronting the lagoon is unsafe for habitation there is potential for similar coseismic coastal subsidence to focus tsunami in other areas with similar tectonic settings

runup distribution for the 1908 messina tsunami in italy observed data versus expected curves the source of the catastrophic 1908 messina tsunami southern italy is studied by best fitting the available datasets of observed runup with a previously published empirical function i e the expected runup distribution the maximum runup is 12 m and was measured 30 40 km to the south of the area where the maximum coseismic dislocation and mercalli cancani sieberg mcs intensities were recorded the observed runup drops from 12 m to less than 1 m in a few tens of kilometers the comparison between observed and expected runup distributions suggests that the main cause of the 1908 tsunami was a mass failure thus supporting previously published evidence including tsunami arrival times bathymetric maps and chronicles reporting the interruption of submarine cables this article adds a significant case history to the very limited database of thoroughly documented runup for landslide tsunamis

tectonic and sedimentary controls on widespread gas emissions in the sea of marmara results from systematic shipborne multibeam echo sounder water column imaging understanding of the evolution of fluid fault interactions during earthquake cycles is a challenge that acoustic gas emission studies can contribute a survey of the sea of marmara using a shipborne multibeam echo sounder with water column records provided an accurate spatial distribution of offshore seeps gas emissions are spatially controlled by a combination of factors including fault and fracture networks in connection to the main marmara fault system and inherited faults the nature and thickness of sediments e g occurrence of impermeable or gas bearing sediments and landslides and the connectivity between the seafloor and gas sources particularly in relation to the eocene thrace basin the relationship between seepage and fault activity is not linear as active faults do not necessarily conduct gas and scarps corresponding to deactivated fault strands may continue to channel fluids within sedimentary basins gas is not expelled at the seafloor unless faulting deformation or erosional processes affect the sediments on topographic highs gas flares occur along the main fault scarps but are also associated with sediment deformation the occurrence of gas emissions appears to be correlated with the distribution of microseismicity the relative absence of earthquake induced ground shaking along parts of the istanbul silivri and princes islands segments is likely the primary factor responsible for the comparative lack of gas emissions along these fault segments the spatiotemporal distribution of gas seeps may thus provide a complementary way to constrain earthquake geohazards by focusing the study on some key fault segments e g the northern part of the locked princes islands segment

geochemistry of komatiites from forrestania southern cross province western australia evidence for crustal contamination the 2 9 ga old forrestania greenstone belt is intermediate in character between typical 3 0 ga and 2 7 ga belts in containing both al depleted and al undepleted komatiites the extensive nickel exploration database on the belt provides a unique opportunity to examine geochemical variations in the context of volcanological evolution within each of the six komatiitic units in the greenstone belt there is a transition from komatiites 18 28 wt mgo in the liquid to high and low magnesium komatiitic basalts 5 18 wt mgo with stratigraphic height and much of the chemical variance within the komatiitic suite can be explained in terms of the addition or fractionation of olivine there are however aspects of the incompatible element signatures which must be attributed to other factors the more primitive komatiites from the lower ultramafic units are al depleted al2o3 tio2 10 5 13 0 and depleted in both light and heavy ree lasmn 0 5 gdybn 1 5 komatiites from the uppermost ultramafic units are variably less depleted in al al2o3tio2 16 5 20 5 this is interpreted to reflect decreasing retention of garnet in the source region of the forrestania komatiites over time and possibly a decrease in the depth of melting within the al depleted suite there are also anomalous enrichments in sio2 feo tio2 and zr which correlate with regional variations in the composition of substrate metasedimentary rocks banded iron formation versus felsic tuff coupled with field evidence for trough structures at the base of lava channel sequences these chemical anomalies provide strong evidence for supracrustal thermal erosion by komatiite lavas the forrestania data indicate that 2 9 ga old komatiites were generated over a range of melting conditions spanning those typical of older and younger archaean sequences and that contamination by supracrustal thermal erosion can influence komatiite chemistry on a regional scale

comparing orthomagmatic and hydrothermal mineralization models for komatiite hosted nickel deposits in zimbabwe using multiple sulfur iron and nickel isotope data trojan and shangani mines are low grade 0 8 ni komatiite hosted nickel sulfide deposits associated with ca 2 7 ga volcano sedimentary sequences of the zimbabwe craton at both mines nickel sulfide mineralization is present in strongly deformed serpentinite bodies that are enveloped by a complex network of highly sheared silicified and sulfide bearing metasedimentary rocks strong polyphase structural metamorphic metasomatic overprints in both the trojan and shangani deposits make it difficult to ascertain if sulfide mineralization was derived from orthomagmatic or hydrothermal processes or by a combination of both multiple s fe and ni isotope analyses were applied to test these competing models massive ores at shangani mine show mass dependent fractionation of sulfur isotopes consistent with a mantle sulfur source whereas s isotope systematics of net textured ore and disseminated ore in talcose serpentinite indicates mixing of magmatic and sedimentary sulfur sources potentially via post magmatic hydrothermal processes a restricted range of strongly mass independent 33s values in ore samples from trojan mine likely reflects high temperature assimilation of sulfur from supracrustal rocks and later superimposed low temperature hydrothermal remobilization iron isotope values for most ni bearing sulfides show a narrow range suggesting that in contrast to sulfur nearly all of iron was derived from an igneous source negative ni isotope values also agree with derivation of ni from ultramafic melt and a significant high temperature fractionation of ni isotopes fe isotope values of some samples from shangani mine are more fractionated than expected to occur in high temperature magmatic systems further suggesting that hydrothermal processes were involved in either low grade ore formation liberation of ni from olivine by sulfur bearing hydrothermal fluids or remobilization of existing sulfides potentially inducing secondary ni sulfide mineralization

a pockmark field in the patras gulf greece and its activation during the 14 7 93 seismic event abstract during a recent oceanographical geophysical survey carried out in the southeastern part of the gulf of patras in western greece for the construction of an outfall an active pockmark field was found the pockmark field was formed in soft layered holocene silts the pockmarks are associated with acoustic anomalies attributed to gas charged sediments the pockmarks vary in size and shape from 25 to 250 m in diameter and from 0 5 to 15 m in depth and are among the largest and deepest observed in the world on july 14th 1993 during the survey a major earthquake of magnitude 5 4 on the richter scale occurred in the area during the 24 hour period prior to the earthquake the bottom water temperature anomalously increased on three occasions whilst for a few days after the earthquake it was noted that the majority of the pockmarks were venting gas bublles it is considered that the three abrupt sea water temperature increases were probably the result of upward migrating high temperature gas bubbles in the water column it is further suggested that the earthquake was the triggering mechanism and that the gas expulsion was caused by the reduction in the pore volume in the sediments resulting from changes in the stress regime prior to the earthquake therefore it can be suggested that in seismic areas adjacent to pockmark fields earthquake prediction may be achieved by monitoring the water temperature and or the rate of gas venting in the pockmark field our analysis indicates that the pockmark field in the patras gulf has formed slowly during the holocene by continuous gas venting which is periodically being interrupted by short duration events of enhanced gas seepage triggered by earthquakes

weathered ni sulfide ore hosting and barren serpentinites in the fortaleza de minas greenstone belt minas gerais brazil a rock geochemical study abstract numerous serpentinites occur in the fortaleza de minas greenstone belt minas gerais brazil one of these serpentinites hosts the o toole massive ni sulfide mineralization this study examines whether the presence of this type of mineralization is reflected in the chemical composition of the serpentinite surface rocks to relate weathered serpentinite composition to the original ultramafic rock composition the extent of post magmatic major element redistribution is evaluated using variation diagrams ternary diagrams and molecular proportion diagrams component analysis is used to identify processes that have determined ultramafic rock composition ascorbic acid hydrogen peroxide cold leach soluble and insoluble fractions of ni are determined as possible useful indicators of mineralized serpentinites it is found that the serpentinites have retained most of their primary ultramafic rock signature component analysis indicates that ultramafic rock composition was largely determined by fractional crystallization of olivine clinopyroxene and spinel two different crystallization trends are identified one trend identifies barren serpentinites the other trend indicates that the ni sulfide mineralization is associated with ultramafic rocks with an feo cr 2 o 3 tio 2 enriched character soluble and insoluble ni fractions do not distinguish the two fractional crystallization trends

geology mineralogy and geochemistry of magnetite associated au mineralization of the ultramafic basalt greenstone hosted crusader complex agnew gold camp eastern yilgarn craton western australia a late archean intrusion related au deposit abstract the crusader complex part of the agnew gold camp of the lawlers anticline of the yilgarn craton western australia is located close to or along the contact between the lawlers basalt and agnew ultramafics units au mineralization within the four orebodies that form the crusader complex is dominated by very pure au containing less than 1 wt ag with au variably associated with scheelite bi tellurides and minor chalcopyrite within a magnetite and titanite gangue assemblage hydrothermal alteration associated with this style of mineralization is characterized by increasing concentrations of mo be li sn and fe and depletions in na cu ba pb mn zn si and k relative to protolith concentrations these enrichments are more typical in orebodies associated with felsic intrusive related mineralizing systems rather than the more well known orogenic au deposits found elsewhere within the lawlers anticline e g at waroonga and within the greater yilgarn craton we propose that flexures of the contact between the lawlers basalt and agnew ultramafic units acted as conduits for au bearing felsic intrusive derived fluids and generated structural traps that enhanced fluid flow the mineralizing fluids that formed the crusader deposits were derived from the lawlers granitoid pluton that intruded into the study area enhanced fluid flow promoted interaction between hydrothermal fluids and the reactive mafic ultramafic rock sequence augmenting the amount of au that was precipitated during formation of the orebodies at crusader the magnetite dominated quartz and sulfide poor intrusion related mineralization at crusader contrasts sharply with other late archean intrusion related deposits of the yilgarn craton that are usually sulfide and or quartz rich this may in turn suggest that the crusader deposit represents a new class of under explored intrusion derived deposits possibly opening new mineral exploration opportunities for the agnew region and potentially the wider eastern goldfields superterrane enrichments in mo and sn and significant depletions in cu suggest that other parts of the lawlers batholith may also be prospective for base metal mineralization integration of stratigraphic interpretation with the identification of key structural fluid pathways and the presence of felsic intrusive bodies as presented in this study enables the delineation of the key elements that underlie mineralization at the crusader complex we propose that these key elements provide vital information for future gold exploration models that can be used within other archean terranes and within the eastern yilgarn craton in particular