surges around the hawaiian islands from the 2011 tohoku tsunami 1 the 2011 tohoku tsunami devastated the northeastern japan coasts and caused localized damage to coastal infrastructure across the pacific the tsunami resulted in strong currents around the hawaiian islands that led to closure of harbors and marinas for up to 38 h after its arrival we utilize a nonhydrostatic model to reconstruct the tsunami event from the seismic source for elucidation of the physical processes and inference of the coastal hazards a number of tide gauges bottom pressure sensors and adcps provided point measurements for validation and assessment of the model results in hawaii spectral analysis of the computed surface elevation and current reveals complex flow patterns due to multiscale resonance standing waves with 33 75 min period develop along the island chains while oscillations of 27 min or shorter are primarily confined to an island or an island group with interconnected shelves standing edge waves with periods 16 min or shorter which are able to form nodes on the reefs and inside harbors are the main driving force of the observed coastal currents resonance and constructive interference of the oscillation modes provide an explanation of the impacts observed in hawaii with implications for emergency management in pacific island communities

coastal impacts of the march 11th tohoku japan tsunami in the galapagos islands on march 11 2011 at 5 46 23 utc march 10 11 46 23 pm galapagos local time the mw 9 0 great east japan earthquake occurred near the tohoku region off the east coast of japan spawning a pacific wide tsunami approximately 12 000 km away the galapagos islands experienced moderate tsunami impacts including flooding structural damage and strong currents in this paper we present observations and measurements of the tsunami effects in the galapagos focusing on the four largest islands in the archipelago from west to east isabela santiagio santa cruz and san cristobal access to the tsunami affected areas was one of the largest challenges of the field survey aside from approximately ten sandy beaches open to tourists all other shoreline locations are restricted to anyone without a research permit open cooperation with the galapagos national park provided the survey team complete access to the islands coastlines survey locations were guided by numerical simulations of the tsunami performed prior to the field work this numerical guidance accurately predicted the regions of highest impact as well as regions of relatively low impact tide corrected maximum tsunami heights were generally in the range of 3 4 m with the highest runup of 6 m measured in a small pocket beach on isla isabela puerto ayora on santa cruz island the largest harbor in the galapagos experienced significant flooding and damage to structures located at the shoreline a current meter moored inside the harbor recorded relatively weak tsunami currents of less than 0 3 m s 0 6 knot during the event comparisons with detailed numerical simulations suggest that these low current speed observations are most likely the result of data averaging at 20 min intervals and that maximum instantaneous current speeds were considerably larger currents in the canal de itabaca a natural waterway between santa cruz island and a smaller island offshore were strong enough to displace multiple 5 5 ton navigation buoys numerical simulations indicate that currents in the canal de itabaca exceeded 4 m s 8 knots a very large flow speed for a navigational waterway

hydrothermal mineralising systems as chemical reactors wavelet analysis multifractals and correlations abstract hydrothermal mineralising systems are discussed as large open flow chemical reactors held far from equilibrium during their life time by deformation and the influx of heat fluid and dissolved chemical species as such they are nonlinear dynamical systems and need to be analysed using the tools that have been developed for such systems hydrothermal systems undergo a number of phase transitions during their evolution and this paper focuses on methods for characterising these transitions in a quantitative manner and establishing whether they resemble either abrupt or continuous critical phase transitions or whether they have some other kind of nature critical phase transitions are characterised by long range correlations for some parameter characteristic of the system power law probability distributions so that there is no characteristic length scale and a high sensitivity to perturbations the transitions undergone in mineralised hydrothermal systems are i widespread non localised mineral alteration involving exothermic mineral reactions that produce hydrous silicate phases carbonates and iron oxides ii strongly localised veining brecciation and or stock work formation iii a series of localised endothermic mineral reactions involving the formation of non hydrous silicates sulphides and metals such as gold iv multiple overprinting repetitions of transitions ii and iii we quantify aspects of these transitions in some gold deposits from the yilgarn craton of western australia using wavelet transforms this technique is convenient and fast it enables one to establish if the transition is multifractal and if so quantify the multifractal or singularity spectrum and to determine the scale dependence of long range correlations or anti correlations other aspects of the spectrum enable quantitative distinctions between sub critical critical and super critical systems the availability of long drill holes with detailed chemical analyses and mineral abundances derived from hyperspectral data enables individual ore bodies to be characterised rapidly in a quantitative manner and constraints placed on whether the various transitions are possibly critical or of some other form we also present some simple nonlinear models including numerical simulation self organised branching and multiplicative cascade processes that produce the multifractal character and correlation scaling relations observed in these data sets distinctions between systems that are strongly and weakly mineralised are discussed

archean gold bearing quartz veins at the sigma mine abitibi greenstone belt quebec part i geologic relations and formation of the vein system the sigma deposit consists of an archean gold bearing vein system in metavolcanic rocks intruded by an irregular body of porphyritic diorite both affected by regional deformation and in turn cut by younger undeformed feldspar porphyry dikes the veins cut all rock types and are composed chiefly of quartz and tourmaline with minor amounts of carbonates pyrite chlorite scheelite and free gold they were emplaced during or after a greenschist facies metamorphism postdating the intrusion of feldspar porphyry dikes the veins were not significantly affected by any subsequent metamorphism or tectonism two principal types of veins occur in the mine subvertical veins and subhorizontal veins they are contemporaneous and cogenetic subvertical veins occur within steeply dipping east west trending ductile shear zones along which reverse subvertical displacements have taken place the veins occupy openings created by overriding of undulations and irregularities of foliation and slip planes during progressive shearing movements within the shears subhorizontal veins occupy extensional fractures which developed between ductile shear zones preferentially in the more competent host rocks these veins were formed by one or several episodes of open space filling geologic relations indicate that the mineralized veins were emplaced progressively in a dynamic tectonic environment during and shortly after the formation of ductile shear zones a structural analysis has shown that the ductile shear zones and the two vein types can be related to a single strain ellipsoid of the following orientation the z axis trending north south and horizontal the y axis plunging 10 degrees west and the x axis plunging 80 degrees east the deformation responsible for the generation of ductile shear zones and emplacement of the veins is ascribed to a late north south trending compression postdating regional deformation

hydrologic segmentation of high temperature shear zones structural geochemical and isotopic evidence from auriferous mylonites of the renco mine zimbabwe abstract combined structural mineralogical and geochemical observations in auriferous mylonites of the renco mine hosted by late archaean high grade metamorphic granitoids in southern zimbabwe are used to describe the spatially heterogeneous fluid flow and metasomatism that occurred synchronous with deformation at mid to upper amphibolite facies metamorphic conditions significantly the narrow on average 1m wide mylonitic shear zones are internally zoned reflecting a pronounced hydrologic segmentation during deformation shear zones typically consist of two distinct domains i anastomosing quartz feldspar biotite hornblende mylonites and or quartz mylonites and ii tabular shaped pods referred to as lithons that are enveloped by mylonites and that exhibit evidence of transient episodes of brittle fracturing and ductile creep whole rock geochemistry and mass balance calculations indicate dramatic element volume up to 100 and associated mass gains for the brittle ductile lithons that are mineralogically reflected in a volumetrically abundant sulphide mineralisation and the formation of a pervasively developed silicate alteration paragenesis in contrast mylonites have experienced only minor element and volumetric changes and minor alteration 18 o values for whole rocks and quartz are enriched in lithons compared to wall rocks and enveloping mylonites which implies the influence of externally derived fluids these results indicate a strongly domainal fluid flow and mass transfer fluid advection was dominated by microscopic and macroscopic fracture permeabilities related to periods of coseismic dilatancy in lithons the patchy but partly interconnected distribution of lithons enveloped by mylonites indicates that deformation in the high temperature shear zones was characterised by transient periods of seismic slip rather than continuous aseismic creep based on the well preserved internal mineralogical and textural development of the renco shear zones a more general model applicable for fluid advection coupled with the rheological behaviour of mid crustal shear zones is presented

gold mineralization in high grade metamorphic shear zones of the renco mine southern zimbabwe the renco gold mine in southern zimbabwe is the only known major gold deposit in the granulite facies terrane of the northern marginal zone of the late archean to mid proterozoic limpopo belt gold mineralization is confined to a system of high temperature mylonite zones characterized by two distinct geometries these include a series of shallow southeasterly dipping anastomosing north northeast to east northeast trending tabular lodes termed shallow reefs and subvertically inclined shallow easterly plunging pipelike lodes termed steep reefs the kinematics and orientation of the mineralized shear zones are consistent with a lateral and frontal thrust zone geometry that formed during the late archean thrusting of the northern marginal zone onto the zimbabwe craton gold is spatially and temporally closely associated with sulfide mineralization including pyrrhotite as the dominant sulfide with minor amounts of chalcopyrite and pyrite associated wall rock alteration comprises a garnet biotite quartz or siderite mineral assemblage mineral textures within the host mylonites as well as garnet biotite thermometry indicate gold deposition at temperatures of about 600 degrees c under mid amphibolite conditions slightly postdating regional peak metamorphic conditions fluid flow in the high temperature shear zones was largely controlled by fracture permeabilities transient episodes of brittle fracturing during conditions of close to lithostatic fluid pressures were promoted by a pronounced strain partitioning within the narrow shear zones into ductile mylonite bands and brittle ductile lithons that contain the bulk of the gold sulfide mineralization the high grade metamorphic ore and alteration mineral assemblages are overprinted by lower greenschist facies parageneses along brittle faults and cataclasites that are related to the mid proterozoic tectonism of the northern marginal zone it is concluded that the mineralization at renco illustrates the rare case of a midcrustal high grade metamorphic gold mineralization in southern africa where the vast majority of late archean lode gold deposits are related to low grade metamorphic granite greenstone terranes

gold quartz veins in metamorphic terranes and their bearing on the role of fluids in faulting gold quartz vein fields in metamorphic terranes such as greenstone belts provide evidence for the involvement of large volumes of fluids during faulting and may be products of seismic processes near the base of the seismogenic regime in the val d or district of the abitibi greenstone belt canada quartz tourmaline carbonate veins form a vein field 30 15 km in the hanging wall of a crustal scale fault zone which was the main channelway for upward migration of the deeply generated fluids the veins occur in small high angle reverse faults and in adjacent horizontal extensional fractures extending up to 75 m in intact rocks they have formed incrementally during active reverse faulting in response to crustal shortening at depths corresponding to those at the base of the seismogenic zone in actively deforming crust detailed structural and fluid inclusion studies provide evidence for generally lithostatic but fluctuating fluid pressures p of the order of 200 mpa and for cyclic stress reversals during vein formation and provide good support for the fault valve model a comparison of vein characteristics with standard earthquake rupture parameters suggests that each slip increment along veins in reverse faults was accompanied by a small earthquake 4 m 3 or less the large vein field thus represents both the extent of fluid dispersion in the hanging wall of a crustal scale channelway and the distribution of small earthquakes integrated over the lifetime of the hydrothermal system it is proposed that such small earthquakes along veins in reverse faults are related to large earthquakes m 6 nucleating near the base of the seismogenic regime along the nearby crustal scale fault either as aftershocks or as a precursory smarm

stress analysis post orogenic extension and 3 01 ga gold mineralisation in the barberton greenstone belt south africa gold deposits in the barberton greenstone belt bgb have formed along a common network of brittle ductile shear zones that developed during extension and emplacement of felsic porphyry dykes at 3015 ma at a deposit scale mineralised shears occur in en echelon arrays distributed as riedel p and anti riedel shears with envelopes that connect groups of mine workings along nnw ene ne and ese trends the dip of the mineralised shear envelopes is generally moderate to steep 50 80 the existence of the directional alignment of gold deposits at the scale of the greenstone belt has been demonstrated with fry analysis stress inversion for mineralised shear zones from workings near 28 mines using a bingham axial distribution and an optimized right dihedron approach provide near identical results with 1 vertical and 3 horizontal nw the stress regime is generally radial extensional or pure extensional at the scale of the greenstone belt the mineralised shear envelopes comprise two sets of near orthogonal trends positioned symmetrically with respect the measured far field stress 1 a nw and ne trending pair with the latter accommodating pure normal slip and the former both dextral or sinistral strike slip and 2 a nnw and ese trending pair accommodating dextral transtensional and sinistral transtensional movements respectively the fact that all mineralised shears developed systematically in response to a similar far field stress suggests that mineralisation formed during a single tectonic stage pb pb ages of 3017 1 17 8 ma and 3008 8 16 ma from a syn mineralisation porphyry dyke near golden quarry indicates gold deposition at 3015 ma i e 85 ma after the craton had stabilised older porphyry dykes intruded near sheba and consort mines have been dated at 3100 ma and 3260 ma respectively and provide a minimum and maximum age constraint on accretionary deformation in the area we propose that the main phase of gold enrichment in the bgb occurred after tectonic and thermal stabilisation of the crust at a time the craton was acting as a stable terrane mineralised brittle ductile shear zones allowed ingress of deeply sourced fluids during cratonic extension mine camps display a cluster spacing of 12 km which suggests a regular distribution of controlling shears possibly as a function of the elastic rigidity of the lithosphere rather than linking mineralisation to orogenic processes during greenstone belt accretion we link gold mineralisation to the opening of fault bounded intracratonic basins including the pongola and witwatersrand basins and concomitant igneous activity

the 16 april 2016 mw 7 8 ms 7 5 ecuador earthquake a quasi repeat of the 1942 ms 7 5 earthquake and partial re rupture of the 1906 ms 8 6 colombia ecuador earthquake the 2016 ecuador m w 7 8 earthquake ruptured the subduction zone boundary between the nazca and south american plates joint modeling of seismic and tsunami observations indicates an 120 km long rupture area beneath the coastline north of the 1998 m w 7 2 rupture the slip distribution reveals two discrete asperities near the hypocenter and around the equator their locations and the patchy pattern are consistent with the prior interseismic geodetic strain which showed highly locked patches also beneath the coastline aftershocks cluster along two streaks one aligned nearly parallel to the plate convergence direction up dip of the main slip patches and the other on a trench perpendicular lineation south of the 1958 rupture zone comparisons of seismic waveforms and magnitudes show that the 2016 event and 1942 earthquakes have similar surface wave magnitude m s 7 5 overlapping rupture areas and similar main pulses of moment rate the same area ruptured as the southernmost portion of the larger earthquake of 1906 m w 8 6 m s 8 6 the seismic behavior reflects persistent heterogeneous frictional properties of the colombia ecuador megathrust

scale integrated architecture of a world class gold mineral system the archaean eastern yilgarn craton western australia abstract world class mineral systems such as those found in the archaean eastern yilgarn craton are the product of enormous energy and mass flux systems driven by lithospheric scale processes these processes can create big footprints or signatures in the lithosphere which can be observed at a range of scales and via a variety of methods including geophysics isotopes tectonostratigraphy and geochemistry we use these datasets to describe both the architecture structure of world class gold systems of the yilgarn craton and the signatures of their formation by applying an understanding of the most critical elements of the process and their signatures new areas especially undercover may be targeted more predictably than before knowledge of the major architectural elements of the yilgarn craton has increased greatly over the last decade through the collection of a wide range of geophysical geochemical and isotopic data these data range in scale from 1 lithospheric scale which provide information on the entire craton and their underlying volumes down to depths in excess of 350 km through 2 regional scale which provide information at the province scale and to depths of 30 40 km to 3 mine and camp scale which provide information on the top few kilometres of the crust the architecture structure in the upper mantle and lower crust can be inferred from broadband seismic tomography and analysis of long wavelength gravity data geophysical data such as magnetotellurics and deep crustal reflection seismic also provide evidence for the signatures of the flow of fluids through this architecture the pathways and they illustrate that the scale of the system is many orders of magnitude larger than the immediate deposit itself of particular importance is the role of deep crustal penetrating shear zones or faults which link the mantle with domes in the upper crust together these data provide first order insights into the physical and chemical properties of the yilgarn craton these insights provide geodynamic clues and constraints as to why the yilgarn is so well endowed in metals such as gold groves et al 1989 the intersection of favourable architectural features provides connections between the mantle and the upper crust in the kalgoorlie region possibly explaining why this area is so well endowed in comparison to others

tectonic and economic implications of trace element 40ar 39ar and sm nd data from mafic dykes associated with orogenic gold mineralisation in central victoria australia abstract mafic to intermediate dykes are spatially and temporally closely associated with major post tectonic granitic complexes in the western lachlan orogen of se australia these dykes which range petrographically from basaltic to andesitic are concentrated within several north to northwest trending zones and were emplaced during two broad intervals of extensive magmatic activity during the silurian devonian period geochemical and sm nd isotopic characteristics of these mafic intrusives are consistent with their formation in a complex subduction related tectonic setting interaction between mantle wedge material sinking oceanic crust and input from the overlying continental crust resulted in the petrological and geochemical variations displayed by these and more felsic dykes throughout the study region field evidence and 40 ar 39 ar data show that in the eastern part of the stawell zone and in the northwest portion of the bendigo zone mafic dyke were intruded between 410 and 400 ma late silurian early devonian further emplacement in the bendigo zone and the eastern part of the melbourne zone took place at between 375 and 365 ma middle to late devonian episodic mantle derived magmatism was possibly related to step wise rollback slab detachment or changes in the angle and rate of westward subduction in response to periodically occurring accretionary pulses a close spatial and temporal relationship also exists between the dykes and orogenic gold mineralisation in the central victorian gold province mafic to intermediate dykes both crosscut and are host to mineralisation in a number of goldfields although there is little evidence for a direct genetic association the two processes are linked by the common utilisation of translithospheric structures which facilitated the rapid ascent into shallow crustal levels of both mantle derived magma and crustal scale ore forming fluid systems previous studies have suggested that transfer of heat into the crust via ascending mafic mantle magmas can provide a thermal engine which triggers and sustains extensive crustal melting thus explaining the commonly observed close association of mafic to intermediate and felsic intrusive suites this study supports the viability of this mechanism and in addition indicates that a causal link exists between the formation of mantle magmas in collisional zones and the generation of orogenic gold deposits

the affinity of archean crust on the yilgarn albany fraser orogen boundary implications for gold mineralisation in the tropicana zone abstract craton margins can be subject to a wide array of gold genesis and redistribution processes although high grade terrains on craton margins are frequently viewed as less prospective than lower grade counterparts in contrast to this the high grade tropicana zone a newly defined archean crustal component on the eastern margin of the yilgarn craton within the albany fraser orogen afo contains a significant proterozoic gold deposit this deposit and zone comprise mid amphibolite to granulite facies gneissic rocks with evidence of partial melting and granite injection the tropicana zone contains significant low si lile enriched granites classed as sanukitoids along with the distinctive compositions the rarity of these rocks within any archean craton suggests that the granitoid protoliths represent a single suite emplaced during one event due to the intense granulite facies overprinting of the tropicana zone rocks determination of the magmatic protolith age for these sanukitoids is challenging nonetheless the best age estimate for magmatism is 2692 16 ma based on the youngest zircons preserving textural evidence of growth within a viscous silicate melt this age is older than compositionally similar magmatism found within the yilgarn craton although a sanukitoid in the northern foreland of the afo has a similar age furthermore the granulite facies metamorphic zircon growth in the tropicana zone at 2718 2554 ma was prolonged compared to that in the yilgarn craton nonetheless the hf isotopic signature of the tropicana zone zircon shares strong similarity to that from the eastern goldfields superterrane of the yilgarn craton this implies that the tropicana zone reflects a deeper crustal level of the yilgarn craton exhumed and thrust nw an unknown distance over the craton edge in addition we observe that the granulite facies zircons have a less radiogenic hf isotope signature than the preserved pre metamorphic zircon cores based on correlations with alpha dose u and th content and 176hf 177hf we suggest this reflects the preferential destruction and release of unradiogenic hf from inherited zircon whereas the protolith sanukitoid zircon with lower u and th content was more resistant to mobilisation during high grade metamorphism we note this situation may be a more general response of the hf isotopic system in which zircon grown in a more mafic melt is less likely to contribute to the metamorphic hf reservoir than its felsic counterpart juvenile granitic veins dated at c 1780 ma intruded into the tropicana zone indicate that the tropicana zone was structurally emplaced at or before c 1780 ma given similar proterozoic magmatic events are well documented from para autochthonous adjacent units re os dating of pyrite coeval with one generation of gold in these rocks indicates model ages of c 2100 ma supportive of a palaeoproterozoic age of mineralisation this mineralisation event is distinct from major proterozoic tectonothermal events elsewhere in the afo sanukitoid magmas are well known for gold fertility and were likely the original source of gold in the tropicana zone which was subsequently concentrated into brittle structures during several episodes gold mineralisation post dated peak metamorphic conditions and is significantly younger than gold mineralisation within other parts of the adjoining yilgarn craton

shelf resonance and impact of near field tsunami generated by the 2010 chile earthquake 1 the 2010 chile earthquake of mw 8 8 generated a destructive tsunami in the near field that resulted in warnings across the pacific numerical modeling shows trapping and amplification of the energy over the continental shelf and slope a spectral analysis of the computed surface elevation reveals resonance oscillations with periods up to 129 min along the central chile coast the temporal and spectral data provides an explanation for the long period waves recorded by dart buoys and the prolonged wave activities and belated impacts reported by residents and survey teams the present study of the 2010 chile tsunami together with those of the 2006 kuril and 2009 samoa tsunamis has directly associated shelf resonance with impacts on insular and continental coasts and provided a tool to identify at risk localities in tsunami hazard assessment

the combined role of bay and shelf modes in tsunami amplification along the coast 1 the role of free modes of oscillation of coastal areas in tsunami amplification at the coast is investigated here a finite element numerical model for modal analysis was applied and the numerically calculated natural frequencies were compared to those resulting from the spectra of measured sea level time series two case studies have been selected that of poverty bay new zealand and that of kuluk bay adak island alaska usa the natural modes of the sea areas that extend in front of these locations are shown to play an important role in tsunami amplification at both the considered bays in fact the enhancement of wave height is found to be related to both the small scale resonance controlled by the coastal shape and the large scale one governed by the continental shelf bathymetry in particular the model application to poverty bay reveals that some of the continental shelf modes are more energetic and occur at frequencies higher than the bay fundamental one these modes are identified as both cross shelf modes and trapped edge waves on the other hand the application to kuluk bay shows that geographical entrapment can be relevant for chain islands making the bay and the continental shelf modes almost coincident

p t x conditions of fluids in the sunrise dam gold deposit western australia and implications for the interplay between deformation and fluids the late archean sunrise dam gold deposit 10 moz is hosted within greenschist facies rocks and is characterized by extreme structural complexity resulting from a protracted deformation history with evidence of structural reactivation and multiple phases of gold mineralization early group i orebodies are hosted within shallow to moderately dipping northwest trending shear zones and occur in foliation parallel veins within a strong penetrative fabric group ii orebodies occur within steeply dipping shear zones and are characterized by veins and breccias and group iii and iv orebodies comprise dominantly stockwork veins the orebodies formed in response to multiple episodes of deformation many structures were created during d1 and d2 shortening whereas the bulk of the gold was deposited during d3 and d4 that marks the transition from a dominantly lithostatic pore fluid regime to hydrostatic conditions two main fluid inclusion types were recognized at sunrise dam low salinity co2 h2o inclusions and co2 inclusions co2 h2o inclusions are more common in the early group i orebodies these fluids were trapped under high p t conditions during d3 minimum estimates suggest conditions were likely 300 c and 1 to 3 kbars predominantly within the one phase field co2 h2o inclusions that occur in later group ii and iii orebodies were trapped predominantly within the two phase field at temperatures 1 3 kbars at a temperature 300 c shear failure along these structures resulted in widespread precipitation of moderate grade gold mineralization from the co2 h2o fluid continued deformation and exhumation modified p t x conditions and cooling of the host rocks below 300 c resulted in the co2 h2o fluid entering the two phase field a combination of temperature decrease a transition from lithostatic to suprahydrostatic and or hydrostatic pressure conditions fluid immiscibility and the influx of a second co2 rich fluid resulted in fracture during d4 and precipitation of high grade gold mineralization in steeply dipping structures forming veins breccias and stockworks

modeling of the 2011 japan tsunami lessons for near field forecast during the devastating 11 march 2011 japanese tsunami data from two tsunami detectors were used to determine the tsunami source within 1 5 h of earthquake origin time for the first time multiple near field tsunami measurements of the 2011 japanese tsunami were used to demonstrate the accuracy of the national oceanic and atmospheric administration noaa real time flooding forecast system in the far field to test the accuracy of the same forecast system in the near field a total of 11 numerical models with grids telescoped to 2 arcsec 60 m were developed to hindcast the propagation and coastal inundation of the 2011 japanese tsunami along the entire east coastline of japan using the noaa tsunami source computed in near real time the model results of tsunami propagation are validated with tsunami time series measured at different water depths offshore and near shore along japan s coastline the computed tsunami runup height and spatial distribution are highly consistent with post tsunami survey data collected along the japanese coastline the computed inundation penetration also agrees well with survey data giving a modeling accuracy of 85 5 for the inundation areas along 800 km of coastline between ibaraki prefecture north of kashima and aomori prefecture south of rokkasho the inundation model results highlighted the variability of tsunami impact in response to different offshore bathymetry and flooded terrain comparison of tsunami sources inferred from different indirect methods shows the crucial importance of deep ocean tsunami measurements for real time tsunami forecasts the agreement between model results and observations along japan s coastline demonstrate the ability and potential of noaa s methodology for real time near field tsunami flooding forecasts an accurate tsunami flooding forecast within 30 min may now be possible using the noaa forecast methodology with carefully placed tsunameters and large scale high resolution inundation models with powerful computing capabilities

broad synchroneity of three gold mineralization styles in the kalgoorlie gold field shrimp u pb and 40ar 39ar geochronological evidence there has been a long standing controversy regarding the timing and number of gold mineralization events at kalgoorlie uranium pb dating of zircons and hydrothermal monazite and xenotime as well as ar 40 ar 39 analysis of metasomatic fuchsite and white mica are used to date pre to synore dikes alteration and orebodies in order to resolve this issue the majority of gold mineralization at kalgoorlie including ductile brittle fimiston brittle ductile oroya and brittle mount charlotte style gold are different expressions of a complex mineralizing system that was active at broadly the same time at ca 2 64 ga gold mineralization was thus deposited in both ductile and brittle structures at approximately the same crustal level at broadly the same time limier similar pt conditions this giant ore system formed after ea 2 69 ga basic magmatism intrusion of the golden mile dolerite sill at 2680 9 ma and intrusion or calc alkaline feldspar quartz porphyry dikes at 2670 5 ma gold mineralization was broadly coeval with lamprophyre dike intrusion at 2642 6 ma and overlapped the waning stages of hornblende and albite bearing porphyry dike emplacement at 2650 6 ma and regional metamorphism subsequent brittle deformation in the kalgoorlie gold held way accompanied by hydrothermal activity that may have led to some late gold mineralization or remobilization in extensional quartz vein arrays in the golden mile between about 2 61 and 2 60 ca this late hydrothermal activity and associated brittle deformation marks the last event to significantly affect the rocks it kalgoorlie and may be related to uplift lift and final cooling of the terrane despite this late event the geometry of the kalgoorlie gold field and its contained lode systems has remained essentially the same since the time of gold mineralization

a succession of near orthogonal horizontal tectonic shortenings in the paleoproterozoic central lapland greenstone belt of fennoscandia constraints from the world class suurikuusikko gold deposit the relative and absolute timing of orogenic gold deposits in complex structural settings are active and challenging topics of research especially in precambrian greenstone belts the suurikuusikko gold deposit in central lapland greenstone belt is currently the largest primary gold producing deposit in europe located on a slight bend of the strike slip kiistala shear zone kisz gold is refractory and locked inside arsenopyrite and pyrite in this study different structural features were investigated along the kisz from the recently stripped etela pit which is the southern extension of the suurikuusikko ore body our data source ranges from aeromagnetic to high resolution aerial images x ray computed tomography scans of selected rock samples and regional geological and geophysical datasets the kisz has recorded five discrete deformation phases spanning between ca 1 92 and 1 76 ga the refractory gold at the suurikuusikko deposit formed during e w contraction related to the d1 thrusting phase this was followed by a n s shortening event d2 where most of the strain was taken up by the northern and southern thrusts tectonic vectors then switched from n s to ne sw and as a result dextral strike slip regime d3 commenced along the kisz this event exsolved invisible gold from the sulfides and remobilized it along with fractures a near orthogonal switch of the regional stress regime from ne sw to nw se flipped the kinematics of the kisz from dextral to sinistral d4 the last deformation phase d5 produced widespread veining under e w contraction and secured gold mineralization at the iso kuotko gold deposit within the kisz

polyphase deformation of mylonites from the renco gold mine zimbabwe identified by crystallographic preferred orientation of quartz abstract gold mineralization at renco mine in the northern marginal zone of the limpopo belt zimbabwe is hosted by a set of intersecting steep and shallow dipping shear zones locally termed reefs both steep and shallow reefs are closely associated with quartz mylonites the crystallographic preferred orientation of quartz from samples of these quartz mylonites indicate that deformation in steep reefs occurred under amphibolite facies conditions pole figures and microstructures of samples from shallow reefs in contrast show evidence for an origin of the auriferous mylonites at amphibolite facies conditions that were subsequently overprinted by deformation under lower greenschist facies conditions since mineralization is hosted by both reef geometries gold mineralization is inferred to have occurred during deformation and associated fluid infiltration along mylonites at amphibolite facies grades coeval with late archaean thrusting of rocks of the northern marginal zone onto rocks of the zimbabwe craton the crystallographic preferred orientation patterns of quartz point to a normal sense of movement during reactivation of the shallow reefs probably related to the meso proterozoic tectonometamorphic event that has affected the central parts of the limpopo belt at ca 2 0 ga normal faulting along the boundary between the northern marginal zone and zimbabwe craton has to date not yet been documented and may provide some important constraints for the understanding of the kinematics of the meso proterozoic tectonics in the limpopo belt

significance of weathering and regolith landscape evolution for mineral exploration in the ne albany fraser orogen western australia abstract the albany fraser orogen afo southeast western australia is an underexplored deeply weathered regolith dominated terrain that has undergone complex weathering associated with various superimposed climatic events for effective geochemical exploration in the afo integrating landscape evolution with mineralogical and geochemical variations of regolith and bedrock provides fundamental understanding of mechanical and hydromorphic dispersion of ore and pathfinder elements associated with the different weathering processes in the neale tenement northeast of the afo a residual weathering profile that is 20 55 m thick was developed under warm and humid climatic conditions over undulating proterozoic sheared granitoids gneisses schists and au bearing mafic rocks from the base the typical weathering profile consists of saprock lower ferruginous saprolite upper kaolinitic saprolite and discontinuous silcrete duricrust or its laterally coeval lateritic residuum these types of duricrusts change laterally into areas of poorly cemented kaolinitic grits or loose lateritic pisoliths and nodules lateritic residuum probably formed on remnant plateaus and was transported mechanically under arid climatic conditions over short distances filling valleys to the southeast erosion of lateritic residuum exposes the underlying saprolite and together with dilution by aeolian sands constitutes the transported overburden 2 25 m thick the reworked lateritic materials cover the preserved silcrete duricrusts in valleys the lower ferruginous saprolite and lateritic residuum are well developed over mafic and sulphide bearing bedrocks where weathering of ferromagnesian minerals and sulphides led to enrichment of fe cu ni cr co v and zn in these units kaolinitic saprolite and the overlying pedogenic silcrete are best developed over alkali granites and quartzofeldspathic gneisses which are barren in au and transition elements and enriched in silica alumina rare earth and high field strength elements a residual au anomaly is formed in the lower ferruginous saprolite above a au bearing mafic intrusion at the hercules prospect south of the neale tenement without any expression in the overlying soil 2 000 m 2 000 250 m 250 53 m 53 2 m and

currents drag and sediment transport induced by a tsunami 1 we report observations of water surface elevation currents and suspended sediment concentration ssc from a 10 m deep site on the inner shelf in northern monterey bay during the arrival of the 2010 chile tsunami velocity profiles were measured from 3 5 m above the bed mab to the surface at 2 min intervals and from 0 1 to 0 7 mab at 1 hz ssc was determined from the acoustic backscatter of the near bed profiler the initial tsunami waves were directed cross shore and had a period of approximately 16 min maximum wave height was 1 1 m and maximum current speed was 0 36 m s during the strongest onrush near bed velocities were clearly influenced by friction and a logarithmic boundary layer developed extending more than 0 3 mab we estimated friction velocity and bed shear stress from the logarithmic profiles the logarithmic structure indicates that the flow can be characterized as quasi steady at these times at other phases of the tsunami waves the magnitude of the acceleration term was significant in the near bed momentum equation indicating unsteady flow the maximum tsunami induced bed shear stress 0 4 n m2 exceeded the critical shear stress for the medium grained sand on the seafloor cross shore sediment flux was enhanced by the tsunami oscillations of water surface elevation and currents continued for several days the oscillations were dominated by resonant frequencies the most energetic of which was the fundamental longitudinal frequency of monterey bay the maximum current speed hourly timescale in 18 months of observations occurred four hours after the tsunami arrived

archean gold relation to granulite formation or felsic intrusions two current models for archean au deposits appeal to granulitization or magmatic processes but new data reveal that neither of these schemes is viable most tonalitic archean granulites are characterized by primary large ion lithophile element lile depletion and so there is no complementary relation to lile enrichment in au deposits nor are k rb k ba k li k cs and th u systematics of granulites and gold deposits complementary published c isotope systematics and c he flux calculations do not support the model of granulitization by influx of mantle c0 2 nor is the total population of 13 c values of au deposits comparable to mantle co 2 or the granulite c reservoir archean tonalite trondhjemite granodiorite ttg magmas are characterized by uniform 87 sr 86 sr whereas the deposits range between 0 701 and 0 720 and average 13 c ranges between 9 and 0 4 with provinciality of sr o and c isotopic signatures moreover fractionated granites trend to normal k rb but higher rb sr and k ba ratios whereas the gold deposits are characterized by main trend or higher k rb and k ba ratios coupled with little cs li or tl enrichment and scattered rb sr ratios many of the deposits postdate the stocks with which they are associated by 20 to 30 m y the variable sr pb c and o isotope systematics but uniform lile trends reflect equilibration of internally or externally derived fluids with compositionally variable crust at low water rock ratios in transpressive accretionary regimes

fluid inclusion record of the hypozonal orogenic renco gold deposit zimbabwe during the retrograde p t evolution the hypozonal renco gold deposit in zimbabwe is hosted by a shear zone system cutting granulite facies enderbites the geologic history of the region testifies to a polyphase tectonometamorphic evolution along the exhumation path three major events are notable during which fluid inclusions could have been formed detailed petrographic work and comparison of calculated isochores with the p t evolution allows correlation of inclusion formation with the tectonometamorphic evolution fluid inclusions in the mineralized lithologies of the renco gold mine are dominated by carbonic inclusions of highly variable densities the high density carbonic inclusions are related to the peak of metamorphism their lower density counterparts show a bimodal occurrence some are re equilibrated equivalents of the inclusions trapped at peak metamorphic conditions whereas others clearly post date this event and are related to gold mineralization the latter type of carbonic inclusions occurs in distinct microstructural domains of quartz crystals i e subgrain grain boundaries therefore these inclusions are interpreted to have formed because of selective trapping of co2 from a mixed h2o co2 low salinity ore fluid all the aqueous inclusions observed at renco can be attributed to a late retrograde greenschist facies overprint

adcp observations of edge waves off oahu in the wake of the november 2006 kuril islands tsunami received 13 september 2007 revised 5 october 2007 accepted 8 november 2007 published 15 december 2007 1 during the 2006 kuril islands tsunami edge waves propagating along oahu s south shore were observed via depth averaged adcp velocity and pressure data acquired in real time by a coastal observatory at 12 m depth and 400 m offshore time varying rotary component velocity spectra obtained via wavelet analysis agree with the phase lag observed between pressure and each cartesian velocity component in indicating the directions of rotation and travel of progressive edge waves furthermore the theoretical ratios between power in the free surface elevation and in each velocity component of edge waves agree with those observed and a nonlinear shallow water model shows edge waves of various modes propagating along the shore near our observation location importantly the maximum surge in sea level occurred at a time when edge waves of all constituent frequencies were superposed citation bricker j d s munger c pequignet j r wells g pawlak and k f cheung 2007 adcp observations of edge waves off oahu in the wake of the november 2006 kuril islands tsunami geophys res lett 34 l23617 doi 10 1029 2007gl032015

multistage gold mineralization events in the archean tati greenstone belt northeast botswana constraints from integrative white mica ar ar garnet u pb and sulfides pb pb geochronology abstract the tati greenstone belt tgb in northeastern botswana hosts numerous au deposits shashe mupane and signal hill associated with sulfides garnet and white mica in this study integrative white mica ar ar garnet u pb and sulfides pb pb dating techniques were combined with whole rock and sulfide pb isotope characteristics to track the source s of gold and constrain the timeframes of gold mineralization events all sulfides and arsenopyrite samples from the tgb yielded overlapping pb pb errorchron ages of 2227 66 ma and 2220 73 ma respectively which coincide with the shashe sulfides pb pb errorchron age of 2250 110 ma these relatively imprecise pb pb dates suggest heterogeneity in the initial pb isotope ratios of sulfides at mupane whereas au mineralization associated hydrothermal almandine garnet yielded overlapping tera wasserburg lower intercept 206pb 238u age and a concordia age of 2119 18 ma mswd 1 03 and of 2105 24 ma mswd of concordance 1 10 respectively sulfides produced an errorchron pb pb age of 2873 140 ma which despite the large error remains geologically meaningful as it coincides within error with the first neoarchean limpopo liberian orogeny 2 70 2 65 ga granitoids intrusion emplacement 2 65 2 73 ga and deposition of banded iron formation 2 73 0 15 ga ore related white mica from signal hill yielded an overlapping ar ar plateau age of 1987 24 ma and a weighted mean ar ar age of 1987 13 ma n 15 mswd 4 3 which coincide within error with the 2 05 1 95 ga second limpopo liberian tectonic cycle herein considered to have possibly triggered the au mineralization in this area the obtained radiometric dates point to at least three well constrained gold mineralization events with two of them possibly triggered by two different regional tectonic events lead isotope compositions of most of the sulfides overlap with those of spatially associated schists and granitoids thus suggesting these units possibly represent pb and by inference au rock sources the genetic model of the tgb au deposits is consistent with many greenstone hosted gold deposits worldwide suggesting our results are not solely of local regional interest but can be used to characterize greenstone hosted gold deposits worldwide

shock capturing boussinesq type model for nearshore wave processes this paper describes the formulation and validation of a nearshore wave model for tropical coastal environment the governing boussinesq type equations include the conservative form of the nonlinear shallow water equations for shock capturing a riemann solver supplies the inter cell flux and bathymetry source term while a godunov type scheme integrates the evolution variables in time the model handles wave breaking through momentum conservation with energy dissipation based on an eddy viscosity concept the computed results show very good agreement with laboratory data for wave propagation over a submerged bar wave breaking and runup on plane beaches as well as wave transformation over fringing reefs the model accurately describes transition between supercritical and subcritical flows as well as development of dispersive waves in the processes

tropicana translated a foreland thrust system imbricate fan setting for c 2520 ma orogenic gold mineralization at the northern margin of the albany fraser orogen western australia

structure and variability of semidiurnal internal tides in mamala bay hawaii 1 moored current meter and temperature observations and results from a three dimensional primitive equation model are used to examine the energetic semidiurnal internal tides present in mamala bay on the south coast of oahu hawaii the steady harmonic component of the internal tide is characterized by large vertical displacements in the central region of the bay 35 m amplitude for the m2 constituent and enhanced alongshelf baroclinic currents at the headlands on either end of the bay 0 27 m s 1 seasonal changes in amplitude and phase are observed the model captures the qualitative spatial structure of the observations baroclinic energy flux estimates from the mooring observations and the numerical simulations suggest that internal tide energy propagates into the bay and does not originate within the bay the model indicates that internal wave generation occurs over the flanks 500 1000 m depth of the ridge predominantly on the east side with perhaps some additional contribution on the west from an energetic internal tide generated north of oahu wave superposition is believed to account for the alongshelf spatial structure of currents and displacements incoherent modulations of the internal tide occur that are not related to local changes in stratification at least on superannual timescales factors contributing to this signal may include stratification variations at the deep generation sites mesoscale activity and or the shoaling of a random internal wave field into the bay from the open ocean

wave driven circulation of a coastal reef lagoon system abstract the response of the circulation of a coral reef system in kaneohe bay hawaii to incident wave forcing was investigated using field data collected during a 10 month experiment results from the study revealed that wave forcing was the dominant mechanism driving the circulation over much of kaneohe bay as predicted theoretically wave setup generated near the reef crest resulting from wave breaking established a pressure gradient that drove flow over the reef and out of the two reef channels maximum reef setup was found to be roughly proportional to the offshore wave energy flux above a threshold root mean square wave height of 0 7 m at which height setup was negligible on the reef flat the wave driven currents increased approximately linearly with incident wave height however the magnitude of these currents was relatively weak typically 20 cm s 1 because of i the mild fore reef slope of kaneohe bay that reduced setup resulting from a combination of frictional wave damping and its re

the 2011 magnitude 9 0 tohoku oki earthquake mosaicking the megathrust from seconds to centuries geophysical observations from the 2011 moment magnitude m w 9 0 tohoku oki japan earthquake allow exploration of a rare large event along a subduction megathrust models for this event indicate that the distribution of coseismic fault slip exceeded 50 meters in places sources of high frequency seismic waves delineate the edges of the deepest portions of coseismic slip and do not simply correlate with the locations of peak slip relative to the m w 8 8 2010 maule chile earthquake the tohoku oki earthquake was deficient in high frequency seismic radiation a difference that we attribute to its relatively shallow depth estimates of total fault slip and surface secular strain accumulation on millennial time scales suggest the need to consider the potential for a future large earthquake just south of this event

an idealized modeling study of nocturnal cooling processes inside a small enclosed basin 1 the advanced regional prediction system is utilized to examine the evolution of the nocturnal boundary layer observed within arizona s meteor crater a small enclosed basin on quiescent nights during the 2006 meteor crater experiment field campaign two aspects of the observed basin atmosphere are investigated a quasi steady state three layer temperature structure including an isothermal layer away from the basin floor and the intrusion of a regional scale cold air drainage flow into the basin in general the two dimensional numerical simulations are able to reproduce the salient features of the nocturnal boundary layer inside meteor crater a combination of increasingly cold air intruding into the basin and pooling near the basin floor and compensating adiabatic ascent yield an isothermal layer over a large depth of the basin atmosphere a series of experiments are then conducted in order to examine the sensitivity of basin thermal structure to upstream terrain slope basin width and the presence of a rim surrounding the basin in the case of a large basin of o 10 km in diameter the cold air intrusion process remains but the larger basin volume yields greater dilution of the cold air intruding into the basin and a weak inversion develops inside the basin away from the floor in the case of a small basin with the same dimensions as meteor crater but with flat upstream terrain the influence of the surrounding terrain on basin cooling is negligible last the presence of a rim surrounding the basin is found to not be necessary for isothermal layer development

granite cored domes and gold mineralisation architectural and geodynamic controls around the archaean scotia kanowna dome kalgoorlie terrane western australia abstract granite cored domes are associated with many of the larger gold deposits of the archaean eastern yilgarn craton of western australia the scotia kanowna dome is eroded to sufficiently deep levels to provide insights into the role granite cored domes play in controlling fluid flow and gold deposition at the centre of the scotia kanowna dome is a granite batholith which is surrounded by outward dipping greenstone belts and associated shear zones this upper crustal dome sits above mid crustal domes providing a series of stacked geometries favourable to focussed fluid flow a number of small to medium sized gold deposits occur on the limbs and the centre of the dome and the world class kanowna belle gold mine occurs on the nose of the dome at least three separate gold mineralising events are defined each of regional significance which can be correlated with other well known gold deposits of the eastern yilgarn craton the palaeostress across this region was dominated by both maximum contractional and extensional vectors oriented perpendicular to the north northwest trending grain the resultant strain is seen in the architecture of the scotia kanowna dome with its margins and associated shear zones controlling the distribution of stratigraphy which is relatively linear and parallel to the margin throughout most of the tectonic history the flanking shear zones were high strain domains that recorded multiple stages of contraction with thrust and mostly sinistral strike slip shear kinematics in contrast the dome nose region was a relatively low strain domain as it was located in the strain shadow of the regional contractional events for example the early extensional record has been preserved at the nose with late stage basins formed in the hangingwall to the extensional faults adding to the stratigraphic complexity of the local region these late basins also may have contributed to the fluid budget in contrast along the flanks of the domes there is no record of these late basins or the extensional faults that controlled their deposition the architecture of the dome played an important role in controlling mineralisation during a significant deviation in the maximum contractional stress vector to an east southeast west southwest orientation at this time basins in the nose region underwent inversion with thrusting to the north and northwest shortening was accommodated along the dome flanks by sinistral strike slip shearing which was relatively free to move due to the mostly linear stratigraphy combined with limited anisotropy and perturbations along the flank however the stratigraphic and geometrical complexity around the dome nose resulted in localised maximum dilation and gold deposition at this time the dome nose area was also a favoured locus for gold enriched dominantly mafic type magmas which are seen as the extensive porphyry swarms in the region these felsic intermediate rocks also may have contributed to the complex fluid budget and are considered as indicators of particular fertility for gold they may have been the primary source for much of the metal endowment the architecture of granite cored domes has played a critical role in focussing magma as well as mineralising fluids into regions of maximum dilation they did this by virtue of their inherent competence and by influencing the position and geometry of shear zones fluid pathways and hence distribution of stratigraphy depositional sites across the region the scotia kanowna dome is a good example of this effect and inferences can be made in favour of similar controls by concealed domes such as beneath kalgoorlie

regional dome evolution and its control on ore grade distribution insights from 3d implicit modelling of the navachab gold deposit namibia abstract we introduce a novel approach to analyse and assess the structural framework of ore deposits that fully integrates 3d implicit modelling in data rich environments with field observations we apply this approach to the early palaeozoic navachab gold deposit which is located in the damara orogenic belt namibia compared to traditional modelling methods 3d implicit modelling reduces user based modelling bias by generating open or closed surfaces from geochemical lithological or structural data without manual digitisation and linkage of sections or level plans instead a mathematically defined spatial interpolation is used to generate 3d models that show trends and patterns that are embedded in large drillhole datasets in our 3d implicit model of the navachab gold deposit distinctive high grade mineralisation trends were identified and directly related to structures observed in the field the 3d implicit model and field data suggest that auriferous semi massive sulphide ore shoots formed near the inflection line of the steep limb of a regional scale dome where shear strain reached peak values during fold amplification this setting generated efficient conduits and traps for hydrothermal fluids and associated mineralisation that led to the formation of the main ore shoots in the deposit both bedding parallel and highly discordant sets of auriferous quartz sulphide veins are interpreted to have formed during the later lock up stage of the regional scale dome additionally pegmatite dykes crosscut and remobilise gold mineralisation at the deposit scale and appear to be related to a younger joint set we propose that kilometre scale active folding is an important deformation mechanism that influences the spatial distribution and orientation of mineralisation in ore deposits by forming structures traps and pathways for fluids at different preferred sites and orientations we also propose that areas that experience high shear strain located along the inflection lines of folds can act as preferred sites for syn deformational hydrothermal mineralisation and should be targeted for regional scale exploration in fold and thrust belts our research also suggests that examination of existing drillhole datasets using 3d implicit modelling is a powerful tool for spatial analysis of mineralisation patterns when combined with fieldwork this approach has the potential to improve structural understanding of a variety of ore deposits

the origin of fluids and nature of fluid rock interaction in mid crustal auriferous mylonites of the renco mine southern zimbabwe geothermometric constraints on auriferous shear zones of the renco mine in the northern marginal zone of the late archaean granulite facies limpopo belt in southern zimbabwe indicate that deformation and associated mineralization occurred at temperatures of at least 600 c up to more likely 700 c mid to upper amphibolite facies conditions during mineralization correspond to the regional scale retrogression of granulite facies wall rocks during the late archaean thrusting of high grade metamorphic rocks of the northern marginal zone onto low to medium grade granite greenstone terrains of the zimbabwe craton mineral assemblages indicate that the ore fluid was moderately oxidized with log fo2 values between 10 17 and 10 18 bars with high h2s activities of 0 25 0 75 elements enriched in the shear zones include au s fe cu mo bi te ni co and h2o au and cu being the most enriched geochemically au correlates with cu but not with s which together with the fact that gold is only rarely intergrown or in direct contact with sulfides possibly indicates a transport of gold as a chloride complex the siting of gold along fractures or within implosion breccias suggests that gold was precipitated due to fluid immiscibility induced by catastrophic fluid pressure drops during seismic slip events fluid inclusions are predominantly co2 ch4 n2 rich but petrographic work indicates that fluid inclusions have undergone extensive post entrapment modifications due to the pervasive recrystallization of mineral textures in the high temperature shear zones the mineralized shear zones are enriched in 18o compared to wall rock enderbites which is interpreted to represent an influx of externally derived fluids of probably metamorphic origin based on temporal and spatial relationships between mineralization late archaean overthrusting of the northern marginal zone onto the zimbabwe craton and coeval amphibolite facies hydration of granulites we suggest that the renco mineralization formed in a mid crustal environment from metamorphic fluids that were generated from dehydration of subcreted greenstone terrains of the zimbabwe craton

edge wave and non trapped modes of the 25 april 1992 cape mendocino tsunami the 25 april 1992 cape mendocino earthquake generated a tsunami characterized by both coastal trapped edge wave and non trapped tsunami modes that propagated north and south along the u s west coast both observed and synthetic time series at crescent city and north spit are consistent with the zero order edge wave mode solution for a semi infinite sloping beach depth profile wave amplitudes at crescent city were about twice that observed at north spit in spite of the fact that the source region was three times farther from crescent city than north spit the largest observed amplitude was due to an edge wave which arrived almost three hours after the initial onset of the tsunami since such waves are highly localized nearshore this suggests that the enhanced responsiveness at crescent city is at least partly due to local dynamic processes furthermore the substantially delayed arrival of this wave which was generated at the southern end of the cascadia subduction zone has significant implications for hazard mitigation efforts along the entire u s west coast specifically this study demonstrates that slow moving but very energetic edge wave modes could be generated by future large tsunamigenic earthquakes in the csz and that these might arrive unexpectedly at coastal communities several hours after the initial tsunami waves have subsided

structural event framework for the eastern yilgarn craton western australia and its implications for orogenic gold abstract the nnw trending tectonic grain of the eastern yilgarn craton eyc was established as a result of predominantly ene wsw directed extension d1 and d3 and e ene w wsw d2 d4 to ne sw directed d5 contraction the result has been a succession of nnw striking temporally discrete fabric elements which can be difficult to interpret reliably at any single location despite this many past workers interpreted the nnw striking fabric as the result of only one regional contractional event and used it as a marker for correlating structural events across the region in order to unravel the complexity this paper presents a new sixfold d1 d6 deformation nomenclature based on 10 000 new mesoscale structural observations including their kinematic analysis and cross cutting relationships these mesoscale data were referenced with regional 3d map patterns stratigraphic magmatic metallogenic considerations and deep seismic reflection images this integrated geodynamic architectural approach is applicable to solving structural event histories in other polydeformed terrains gold mineralisation occurred during the first five events but was particularly concentrated from d3 onwards the d3 event marked the most profound change in the tectonic evolution of the eyc with changes in greenstones granites and tectonic mode lithospheric extension and core complexes with the first significant gold deposited within extensional shear zones that dissect the crust later contraction d4 was imposed at a high angle to the previously established anisotropic architecture the outcome was the creation of a new dynamic permeability framework which resulted in gold mineralisation during nnw striking sinistral strike slip faulting and associated thrusting a further stress switch d5 further modified the architecture resulting in n to nne striking dextral strike slip faulting and the final period of gold mineralisation before late stage extension d6

lithospheric controls on the formation of provinces hosting giant orogenic gold deposits ages of giant gold systems 500 t gold cluster within well defined periods of lithospheric growth at continental margins and it is the orogen scale processes during these mainly late archaean palaeoproterozoic and phanerozoic times that ultimately determine gold endowment of a province in an orogen a critical factor for giant orogenic gold provinces appears to be thickness of the subcontinental lithospheric mantle sclm beneath a province at the time of gold mineralisation as giant gold deposits are much more likely to develop in orogens with subducted oceanic or thin continental lithosphere a proxy for the latter is a short pre mineralisation crustal history such that thick sclm was not developed before gold deposition in constrast orogens with protracted pre mineralisation crustal histories are more likely to be characterised by a thick sclm that is difficult to delaminate and hence such provinces will normally be poorly endowed the nature of the lithosphere also influences the intrinsic gold concentrations of potential source rocks with back arc basalts transitional basalts and basanites enriched in gold relative to other rock sequences thus segments of orogens with thin lithosphere may enjoy the conjunction of giant scale fluid flux through gold enriched sequences although the nature of the lithosphere plays the crucial role in dictating which orogenic gold provinces will contain one or more giant deposits the precise siting of those giants depends on the critical conjunction of a number of province scale factors such features control plumbing systems traps and seals in tectonically and lithospherically suitable terranes within orogens

estimating the effect of earth elasticity and variable water density on tsunami speeds the speed of tsunami waves is typically calculated using the shallow water approximation over a rigid body earth recent comparisons of tsunami arrival times from the 11 march 2011 tsunami suggest however that the standard formulation has errors around the 1 level and it has been suggested that the elasticity of the earth can explain the discrepancy while previous work has indeed shown that such elastic deformation can modify tsunami speeds the effect has been neglected partly due to the difficulty in understanding how large this elastic effect is here we remedy this by providing a new derivation and expression for how to incorporate the first order effect that solid earth elasticity and ocean water compressibility have on tsunami speeds this result is shown to agree approximately with previous theory and helps to explain observed timing discrepancies from the 11 march 2011 tsunami the dispersive elastic correction and the non dispersive compressibility correction together may account for the majority of the observed discrepancy

frontal wedge deformation near the source region of the 2011 tohoku oki earthquake 1 we report an uplift of 5 m with a horizontal displacement of more than 60 m due to the 2011 tohoku oki earthquake the uplift was measured by an ocean bottom pressure gauge installed before the earthquake on a frontal wedge which formed an uplift system near the japan trench horizontal displacements of the frontal wedge were measured using local benchmark displacements obtained by acoustic ranging before and after the earthquake the average displacements at the frontal wedge were 58 m east and 74 m east southeast these results strongly suggest a huge coseismic slip beneath the frontal wedge on the plate boundary the estimated magnitude of the slip along the main fault was 80 m near the trench our results suggest that the horizontal and vertical deformations of the frontal wedge due to the slip generated the tremendous tsunami that struck the coastal area of northeastern japan

survey of 2011 tohoku earthquake tsunami inundation and run up 1 at 14 46 local time on march 11 2011 a magnitude 9 0 earthquake occurred off the coast of northeast japan this earthquake generated a tsunami that struck japan as well as various locations around the pacific ocean with the participation of researchers from throughout japan joint research groups conducted a tsunami survey along a 2000 km stretch of the japanese coast more than 5300 locations have been surveyed to date generating the largest tsunami survey dataset in the world on the sendai plain the maximum inundation height was 19 5 m and the tsunami bore propagated more than 5 km inland along the ria coast from about 50 to 200 km north of sendai the narrow bays focused the tsunami waves generating the largest inundation heights and run ups the survey data clearly show a regional dependence of tsunami characteristics

the evolution of a precambrian arc related granulite facies gold deposit evidence from the glenburgh deposit western australia abstract gold deposits are rare in upper amphibolite to granulite facies environments known examples commonly attract debate about whether they formed under these conditions or instead represent metamorphosed metasomatic or superimposed retrograde mineralization the glenburgh gold deposit is located in the paleoproterozoic upper amphibolite to granulite facies glenburgh terrane in the southern gascoyne province of western australia gold at the glenburgh deposit is free and disseminated within quartz biotite garnet gneiss amphibolite and post gold quartz chlorite veins no clear association with a specific host lithology has been identified and mineralization does not have a visually distinct proximal alteration assemblage the rocks hosting the deposit represent a distinct sedimentary package that was deposited mineralized buried and metamorphosed all during arc magmatism features within the internal structure of gold grains such as high purity gold veinlets incoherent twinning and low silver content suggest the gold has been through post depositional processes such as metamorphism and deformation abundant sulfide minerals are interpreted to have formed by sulfidation of the host rock contemporaneously with gold mineralization and the presence of rounded sulfide inclusions within garnet porphyroblasts illustrates the presence of a sulfide phase prior to peak metamorphism geochronology of zircon and monazite constrains the timing of mineralization to be younger than c 2035 ma the maximum depositional age of the metasedimentary host rocks but older than c 1991 ma the peak of m1 metamorphism during the glenburgh orogeny these events were synchronous with arc magmatism rocks at the glenburgh deposit were likely deposited in a fore arc or accretionary wedge a favourable setting for porphyry cu mo au epithermal au polymetallic sn w skarn and orogenic au mineralization phase equilibria modelling of a pelitic migmatite constrains peak p t conditions to be 865 885 c 6 8 7 6 kbar consistent with elevated thermal gradients within the arc followed by conductive cooling of arc magmas partial melting during peak m1 metamorphism possible caused gold remobilization the lack of an alteration assemblage further suggests that the alteration assemblage and mineralization were recrystallized during deformation and metamorphism however increases in ca and k abundance and magnetic susceptibility decreases toward mineralization suggesting that they may constitute ore vectors

shear zones fault networks and archean gold conjugate ductile shear zones developed mostly on granite greenstone margins are a dominant structural feature of the yilgarn craton these greenstone belt scale shear zones lack both gold deposits and gold related alteration previous interpretations of the shear zones as part of a linked system as craton scale terrane boundaries or as crustal scale pathways for gold mineralizing fluids all appear equivocal instead gold mineralizing fluids in the yilgarn craton illustrated here by the gold rich yandal belt were focused by a network of middle to upper crustal brittle faults in the late archean the faults are 040 to 060 trending dextral and 090 to 120 trending sinistral the maximum compression direction is about 075 gold mineralization occurs in laminated and other schistosity parallel quartz veins where brittle faults refract along earlier subsidiary within greenstone ductile shear zones and in quartz veins within late archean faults

the role of early formed structures on the development of the world class st ives goldfield yilgarn wa a revised structural interpretation for the victory to kambalda area of the world class st ives goldfield in the archean yilgarn craton has mapped out the distribution of wnw trending faults within this area of the field these previously cryptic wnw trending structures had been identified in gravity data and also by isopach thickness variations the wnw trending faults acted as transfers syn gold mineralization although only discrete segments of these faults were active during the main stage of gold mineralization where mineralized the faults transferred strain from a complex combination of block on block movement associated with thrusting and strike slip movement on nw and n trending faults along some segments n trending mineralized faults terminate against the wnw trending faults many of the wnw trending faults correlate with major strike changes on regional and camp scale faults and they are domain boundaries for the critical n trending fault segments that host high grade gold within contractional jogs the wnw trending faults also show evidence for an older deformation history prior to main stage gold which may extend back to early basin development associated with ultramafic and mafic volcanism they are inferred to have been a series of early wnw trending normal faults and breached relay ramps associated with oblique rifting along an older nnw trending basement boundary

granulite hosted gold tectonic setting and lithogeochemistry of the tropicana deposit western australia the tropicana gold deposit 7 9 moz is hosted by the neoarchean amphibolite to granulite grade tropicana gneiss these rocks form part of the plumridge terrane a tectonic unit that separates the in situ eastern margin of the yilgarn craton from proterozoic elements of the albany fraser orogen western australia the gneissic host package to the orebody originally constituted a suite of medium to high k calc alkaline and adakitic basaltic to rhyolitic lavas emplaced in a relatively thick crustal continental margin arc amphibolitized mafic intrusions have back arc basin basalt like compositions consistent with their having formed during extension and incipient rifting of the arc gold mineralization occurs mainly within a sheet like syenitic gneiss that ranges compositionally from basaltic andesite to rhyolite and derived through metasomatism of compositionally equivalent lavas within an interpreted shear zone coarse perthite textures in microcline ruffle exsolution in brown biotite and occasional pyrite inclusions away from fractures in microcline porphyroblasts indicate that this shear zone predated peak metamorphism relative to the unmineralized host gneisses the mineralized syenitic gneisses show significant enrichments in s and the ore elements mo te tl ag au w and occasionally bi and sb but not as cu or zn in the k group elements and also in p light rare earth elements lree th u zr and hf depletions in most major elements si ti fe mg and ca as well as v cr ni and co are considered to reflect dissolution of relatively low volume mafic phases hornblende augite fe ti oxides and plagioclase in the protoliths some of the distinctive enrichments p lree zr hf are linked to volume loss in excess of 50 associated with dissolution of silica and concentration of insoluble apatite and zircon in the mineralized unit but the ore elements and strongly enriched similar to x10 th and u were added from the hydrothermal fluids involved exhumation of the tropicana gneiss into the upper crust was accompanied by fluid ingress and retrogression this produced mm to cm scale wavy biotite pyrite shears solution seams and disseminations throughout the syenitic gneiss which were further retrogressed to sericite chlorite assemblages in places both of which host most of the gold in the deposit thus although the present deportment of gold is unambiguously associated with the postpeak metamorphic greenschist grade retrogression at ca 2520 ma there is compelling evidence that the paucity of quartz and carbonate veining atypical element enrichments and sheet like nature of the tropicana deposit in part reflect metasomatism associated with a prepeak metamorphic relatively deep shear zone at present we have no direct evidence for the timing of introduction of gold and a protracted history of gold precipitation redistribution and enrichment is implied

archean magmatic granulites diapirism and proterozoic reworking in the northern marginal zone of the limpopo belt the northern marginal zone nmz of the limpopo belt southern africa is a high grade gneiss belt dominated by magmatic granulites of the charnoenderbite suite which intruded minor mafic ultramafic and metasedimentary rocks between 2 74 and 2 57 ga the intrusive rocks have crustal and mantle components and occur as elliptical bodies interpreted as diapirs peak metamorphism p 800 mpa t 800 850 c occurred at ca 2 59 ga the highly radiogenic nature of the rocks in the nmz supplemented by heat from mantle melts led to heating and diapirism culminating in the intrusion of distinctive porphyritic charnockites and granites horizontal shortening and steep extrusion of the nmz during which crustal thickening was limited by high geothermal gradients contrast with overthickening and gravitational collapse observed particularly in more recent orogens the granulites were exhumed by the end of the archean the pervasive late archean shortening over the whole of the nmz contrasts with limited deformation on the zimbabwe craton possibly owing to the strengthening effect of early crust in the craton in the southeast of the nmz strike slip kinematic indicators occur within the transition zone and the triangle shear zone where dextral shearing reworked the archean crust at ca 1 97 ga

diversity within a unified model for archaean gold mineralization in the yilgarn craton of western australia an overview of the late orogenic structurally controlled gold deposits abstract the archaean yilgarn craton has produced 3000 tonnes of gold mainly from structurally controlled deposits that formed during the latest stages of an orogenic event that affected the entire craton and culminated in the period 2 66 2 63 ga as a group these late orogenic deposits encompass a wide range of host rocks structural settings and structural styles and alteration types however several consistent features justify grouping the deposits into a single class of mineralization these features include timing relative to orogenesis high gold to base metal ratios an association with potassium metasomatism and carbonation of host rocks low sulfide contents and a low salinity h 2 o co 2 ch 4 ore fluid most deposits formed in domains of low mean stress during east west regional compression and preserve evidence in the form of quartz vein arrays and hydraulic breccias for high fluid pressures and rock dilation the range of ore depositional conditions implied by alteration assemblages at various deposits makes the term mesothermal an inappropriate description for this class of mineralization the term late orogenic structurally controlled gold deposits is proposed as one which more completely encompasses the class of mineralization described in this overview late orogenic structurally controlled gold deposits formed in thermal equilibrium with high grade metamorphic rocks at the margins of the greenstone belts but were retrograde with respect to lower grade host rocks in the cores of greenstone belts these relationships probably reflect diachronous metamorphism and a single gold mineralization event which was contemporaneous with the later high grade metamorphism geochronological data indicate gold deposition at ca 2 63 ga in the western part of the yilgarn craton isotopic data suggest similar depositional ages in the eastern part of the craton eastern goldfields superterrane but this timing is difficult to reconcile with field relationships that suggest broad contemporaneity between regional metamorphism and gold mineralization at ca 2 66 ga the main competing genetic models for late orogenic structurally controlled gold mineralization in the yilgarn craton propose an orthomagmatic deeply sourced or metamorphogenic ore fluid none of these models can account satisfactorily for all the features of the late orogenic structurally controlled gold deposits

involvement of variably sourced fluids during the formation and later overprinting of paleoproterozoic au cu mineralization insights gained from a fluid inclusion assemblage approach abstract au cu mineralized quartz veins of the reef deposit wisconsin usa originally formed prior to or early in the paleoproterozoic penokean orogeny in central north america as either the root zone of a gold rich vms deposit or in an orogenic gold setting nearly 400 m y later magmatic hydrothermal fluids associated with a continental scale anorogenic magmatic event remobilized mineralization within the veins and still later during the paleozoic remobilization and perhaps upgrading of au and other metals occurred in response to circulation of fluids associated with mississippi valley type deposits found in overlying supracrustal rocks fluid constraints on the formation of the reef deposit and later overprinting over a 1 5 b y timeframe are examined using the fluid inclusion assemblage fia approach distinctive assemblages are examined on individual merit each offering individual stories to aid in our understanding of the protracted development of the reef deposit presumably primary fluid inclusions in au and cu bearing quartz sulfide veins that formed during the paleoproterozoic event show h2o co2 ch4 nacl compositions based on microthermometry and laser raman spectroscopy possibly primary h2o nacl and secondary h2o co2 ch4 nacl fia formed prior to regional deformation and are recognized as discrete relict and neonate clusters the intersection of isochores from the highest density neonate inclusions of either fluid composition indicates re equilibration at lower amphibolite conditions during regional deformation quartz hosted secondary fluid inclusion assemblages characterized by h2o ch4 and co2 ch4 compositions formed at high temperatures and have not been re equilibrated and are interpreted to post date regional metamorphism these fia occur along healed fractures with chalcopyrite mineralization these inclusions are likely associated with fluid circulation driven by emplacement of the adjacent wolf river batholith ca 1 45 ga that altered pyrite to pyrrhotite and remobilized or emplaced chalcopyrite at temperatures as high as 700 c this reduced fluid was in equilibrium with locally observed graphitic sediments secondary lower temperature

resonance in hawaii waters from the 2006 kuril islands tsunami 1 the 2006 kuril islands tsunami while not destructive to coastal properties resulted in prolonged oscillations in hawaii waters this study examines the oscillation patterns and amplification through reconstruction of the tsunami using a nonlinear shallow water model after validation with water level measurements a fast fourier transform of the computed surface elevation reveals profound oscillation modes at various periods around the hawaiian islands the oscillation at the regional scale consists of standing waves across the island chain and resonance in interconnected channels embayments and shallow shelves resonance in embayments and standing edge waves dominate the oscillation in coastal waters the results show strong correlation between bathymetric features and resonance oscillations and identify tsunami hazard areas for planning and emergency management

structural controls on gold mineralization on the margin of the yilgarn craton albany fraser orogen the tropicana deposit western australia the tropicana gold deposit is located adjacent to the margin of the yilgarn craton in the albany fraser orogen western australia the deposit is hosted in granulite facies quartzo feldspathic gneisses of the archean tropicana gneiss ore bodies comprise biotite pyrite alteration concentrated in shear zones that formed during ne sw shortening in the late archean and clearly postdate the formation and deformation of high grade gneiss fabrics d1 and d2 the orientation of the ore bodies is controlled by the shear zones that are in turn localised by the gneissic banding mineralization also involved solution and coeval microfracturing and veining of more competent pegmatitic units the mineralizing event d3 was followed by at least two further deformations which reactivated and overprinted the biotite fabrics with sericite and chlorite created new shear zones and affected gold distribution d5 consisted of dextral shear on e w shear zones which subdivide the deposit into five major structural domains the importance of structurally controlled permeability at tropicana is similar in cratonic lode gold deposits as is the protracted deformation fluid flow history like renco mine in zimbabwe tropicana gold deposit was formed by hydrothermal fluid flow peripheral to the craton economic gold mineralization was clearly post peak metamorphism

validating velocities in the geoclaw tsunami model using observations near hawaii from the 2011 tohoku tsunami the ability to measure predict and compute tsunami flow velocities is of importance in risk assessment and hazard mitigation substantial damage can be done by high velocity flows particularly in harbors and bays even when the wave height is small moreover advancing the study of sediment transport and tsunami deposits depends on the accurate interpretation and modeling of tsunami flow velocities and accelerations until recently few direct measurements of tsunami velocities existed to compare with model results during the 11 march 2011 tohoku tsunami 328 current meters were in place around the hawaiian islands usa that captured time series of water velocity in 18 locations in both harbors and deep channels at a series of depths we compare several of these velocity records against numerical simulations performed using the geoclaw numerical tsunami model based on solving the depth averaged shallow water equations with adaptive mesh refinement to confirm that this model can accurately predict velocities at nearshore locations model results demonstrate tsunami current velocity is more spatially variable than waveform or height and therefore may be a more sensitive variable for model validation

kuril islands tsunami of november 2006 2 impact at crescent city by local enhancement 1 crescent city cc is particularly susceptible to tsunami attack the combination of tsunami signal enhancement by both distant bathymetric features and local nearshore resonance seems to be responsible for this behavior application of global tsunami propagation models to the kuril islands tsunami of november 2006 in the companion paper kowalik et al 2008 delineated the importance of distant bathymetric features for both tsunami wave amplification and for increased duration of the tsunami arriving at cc these distant features were responsible for delivering the late high energy signal which was delayed by 2 hours from the predicted arrival time additional local amplification and increased duration are caused by the shelf bathymetry adjacent to cc as the initial tsunami arrives at cc the shelf trapping mechanism tends to excite the gravest of the natural modes this oscillation is slowly shifted toward the natural mode closest to the period of the incident tsunami wave packet short duration wave trains tend to influence the tsunami response at cc harbor in such a way that 1 hour after the first wave arrival a much stronger wave will be generated owing to the tendency of the shelf to initially ring at the frequency of the gravest mode practical implications of distant and local amplification relate to the potential hazard near cc highlighting the need for awareness of the tsunami signal duration in this respect two timescales are important for this event the 2 hour time delay due to distant bathymetric features and the 1 hour delay due to local offshore bathymetry

numerical simulation of the 2011 tohoku tsunami based on a new transient fem co seismic source comparison to far and near field observations in this work we simulate the 2011 m9 tohoku oki tsunami using new coseismic tsunami sources based on inverting onshore and offshore geodetic data using 3d finite element models fem such fems simulate elastic dislocations along the plate boundary interface separating the stiff subducting pacific plate from the relatively weak forearc and volcanic arc of the overriding eurasian plate due in part to the simulated weak forearc materials such sources produce significant shallow slip several tens of meters along the updip portion of the rupture near the trench to assess the accuracy of the new approach we compare observations and numerical simulations of the tsunami s far and near field coastal impact for i one of the standard seismic inversion sources ucsb shao et al 2011 and ii the new fem sources specifically results of numerical simulations for both sources performed using the fully nonlinear and dispersive boussinesq wave model funwave tvd are compared to dart buoy gps tide gauge and inundation runup measurements we use a series of nested model grids with varying resolution down to 250 m nearshore and size and assess effects on model results of the latter and of model physics such as when including dispersion or not we also assess the effects of triggering the tsunami sources in the propagation model i either at once as a hot start or with the spatiotemporal sequence derived from seismic inversion and ii as a specified surface elevation or as a more realistic time and space varying bottom boundary condition in the latter case we compute the initial tsunami generation up to 300 s using the non hydrostatic model nhwave although additional refinements are expected in the near future results based on the current fem sources better explain long wave near field observations at dart and gps buoys near japan and measured tsunami inundation while they simulate observations at distant dart buoys as well or better than the ucsb source none of the sources however are able to explain the largest runup and inundation measured between 39 5 and 40 25 n which could be due to insufficient model resolution in this region sanriku ria of complex bathymetry topography and or to additional tsunami generation mechanisms not represented in the coseismic sources e g splay faults submarine mass failure this will be the object of future work

late kinematic timing of orogenic gold deposits and significance for computer based exploration techniques with emphasis on the yilgarn block western australia abstract orogenic gold deposits are a widespread coherent group of epigenetic ore deposits that are sited in accretionary or collisional orogens they formed over a large crustal depth range from deep seated low salinity h2o co2 ch4 n2 ore fluids and with au transported as thio complexes regional structures provide the main control on deposit distribution in many terranes first order faults or shear zones appear to have controlled regional fluid flow with greatest ore fluid fluxes in and adjacent to lower order faults shear zones and or large folds highly competent and or chemically reactive rocks are the most common hosts to the larger deposits focusing of supralithostatic ore fluids into dilatant zones appears to occur late during the evolutionary history of the host terranes normally within d3 or d4 in a d1 d4 deformation sequence reactivation of suitably oriented pre existing structures during a change in far field stress orientation is a factor common to many deposits and repeated reactivation may account for multiple mineralization episodes in some larger deposits absolute robust ages of mineralization support their late kinematic timing and in general suggest that deposits formed diachronously towards the end of the 100 to 200 m y long evolutionary history of hosting orogens for example in the yilgarn block a region specifically emphasised in this study orogenic gold deposits formed in the time interval between 40 and 90 m y with most about 60 to 70 m y after the youngest widespread basic ultrabasic volcanism and towards the end of felsic magmatism the late timing of orogenic gold deposits is pivotal to geologically based exploration methodologies this is because the present structural geometries of i the deposits ii the hosting goldfields and iii the enclosing terranes are all essentially similar to those during gold mineralization at least in their relative position to each other thus interpretation of geological maps and cross sections and three dimensional models can be used to accurately simulate the physical conditions that existed at the time of ore deposition it is particularly significant that the deposits are commonly related to repetitive and predictable geometries such as structural heterogeneities within or adjacent to first order structures around rigid granitoid bodies or in specific locked up fold thrust structures importantly the two giant greenstone hosted goldfields kalgoorlie and timmins show a remarkably similar geometry at the regional scale computer based stress mapping and gis based prospectivity mapping are two computer based quantitative methodologies that can utilize and take advantage of the late timing aspect of this deposit type to provide important geological aids in exploration both in broad regions and more localized goldfields both require an accurate and consistent solid geology map stress mapping requires knowledge of the far field stresses during mineralization and the empirical prospectivity mapping requires data from a significant number of known deposits in the terrane the kalgoorlie terrane in the yilgarn block meets these criteria and illustrates the potential of these methodologies in the exploration for orogenic gold deposits low minimum stress anomalies interpreted to represent dilational zones during gold related deformation coincide well with the positions of known goldfields rather than individual gold deposits in the terrane and there are additional as yet unexplained anomalies the prospectivity analysis confirms that predictable and repetitive factors controlling the siting of deposits are i proximity to and orientation and curvature of granitoid greenstone contacts ii proximity to segments of crustal faults which strike in a preferred direction iii proximity to specific lithological contacts which have similar preferred strike iv proximity to anticlinal structures and v the presence of preferred reactive host rocks e g dolerite the prospectivity map defines a series of anomalous areas which broadly conform to those of the stress map 78 correspondence the most prospective category on this map covers less than 0 3 of the greenstone belts and yet hosts 16 of the known deposits which have produced 80 of known gold thus it discriminates in favour of the larger economically more attractive deposits in the terrane the successful application of stress mapping and prospectivity mapping to geology based exploration for orogenic gold deposits indicates that more quantitative analysis of geological map data is a profitable line of research the computer based nature of these methodologies is ideal for the production of an ultimate integrated deposit target map which can be compared to other more conventional targeting parameters such as geophysical and geochemical anomalies such an integrated strategy appears the way forward in the increasingly difficult task of cost effective global exploration for orogenic gold deposits in poorly exposed terranes

orogenic gold common or evolving fluid and metal sources through time abstract orogenic gold deposits of all ages from paleoarchean to tertiary show consistency in chemical composition they are the products of aqueous carbonic fluids with typically 5 20 mol co 2 although unmixing during extreme pressure fluctuation can lead to entrapment of much more co 2 rich fluid inclusions in some cases ore fluids are typically characterized by significant concentrations of ch 4 and or n 2 common estimates of 0 01 0 36 mol h 2 s a near neutral ph of 5 5 and salinities of 3 7 wt nacl equiv with na k ca mg this fluid composition consistency favors an ore fluid produced from a single source area and rules out mixing of fluids from multiple sources as significant in orogenic gold formation nevertheless there are broad ranges in more robust fluid inclusion trapping temperatures and pressures between deposits that support a model where this specific fluid may deposit ore over a broad window of upper to middle crustal depths much of the reported isotopic and noble gas data is inconsistent between deposits leading to the common equivocal interpretations from studies that have attempted to define fluid and metal source areas for various orogenic gold provinces fluid stable isotope values are commonly characterized by the following ranges 1 18 o for precambrian ores of 6 to 11 and for phanerozoic ores of 7 to 13 2 d and 34 s values that are extremely variable 3 13 c values that range from 11 to 2 and 4 15 n of 10 to 24 for the neoarchean 6 5 to 12 for the paleoproterozoic and 1 5 to 10 for the phanerozoic secular variations in large scale earth processes appear to best explain some of the broad ranges in the o s and n data fluid rock interaction particularly in ore trap areas may cause important local shifts in the o s and c ratios the extreme variations in d mainly reflect measurements of hydrogen isotopes by bulk extraction of waters from numerous fluid inclusion generations many which are not related to ore formation radiogenic isotopes such as those of pb sr nd sm and os measured on hydrothermal minerals are even more difficult to interpret for defining metal source particularly as the low salinity ore fluids transport limited amounts of these elements and significant amounts of these may be locally added to the minerals during alteration reactions at the sites of gold deposition noble gas and halogen data are equally equivocal fluid exsolution from granitoids emplaced into the upper and middle crust metamorphism of the crust or fluids entering trans crustal fault zones from below the crust all remain as permissive scenarios associated with orogenic gold formation as the abundant geochemical data are equivocal however geological and geochronological data weigh heavily against a magmatic hydrothermal model in the upper to middle crust there is no universal temporal association between orogenic gold and magmatism and where there is an overlap in age there is no specific type of magmatism consistently associated with gold formation nor element zonation around any specific pluton a crustal metamorphic model for fluid and metal sources is very consistent with geological geochronological and geochemical data although metamorphism on a regional scale that releases these components into major fault zones can be associated with many processes along active continental margins these can include crustal thickening and radiogenic heating slab rollback and heating during crustal extension or subduction of a spreading ridge heating the base of an accretionary prism in rare examples where phanerozoic orogenic gold deposits are hosted in precambrian high grade metamorphic terranes fluids and metals must however enter a transcrustal fault system from a sub crustal source this could either be a devolatilized subducted relatively flat perhaps stalled slab and its overlying sediment or the corner of the fertilized mantle wedge that releases a fluid during a thermal event

what controls gold distribution in archean terranes despite intensive efforts determination of a predictable pattern of gold distribution to enhance process understanding and simplify exploration has remained elusive the pattern of gold distribution along the archean boulder lefroy shear zone in the yilgarn craton of western australia provides insights into gold distribution in one of the world s richest provinces four world class gold deposits including the giant golden mile at kalgoorlie are regularly spaced along the shear zone providing a window into understanding large scale archean hydrothermal systems relationships among gold endowment shear zone trend and geologic complexity as measured by fractal dimensions indicate that 1 ore fluids were focused into those parts of the shear zone with greatest misorientation from the regional trend which define dilational sites during shearing and became the sites of world class gold deposits and 2 the degree of complexity contrast along the shear zone modulated gold endowment

resonance and impact of the 2009 samoa tsunami around tutuila american samoa 1 the 2009 samoa tsunami resulted in severe damage and inundation at tutuila american samoa the disparity of the impact and the varying accounts of the tsunami along the coast remain one of the most intriguing aspects of the event we utilize a dispersive wave model to reconstruct the tsunami from the earthquake source for understanding of the wave dynamics around tutuila after validation with water level measurements a fast fourier transform of the computed surface elevation reveals coupled resonance oscillations between 3 and 18 min period over the insular slope and shelf as well as the fringing reefs the resonance which focuses energy according to shelf and embayment configurations provides an explanation of the runup data and eyewitness accounts and identifies the coastal communities prone to tsunami hazards

boussinesq type model for energetic breaking waves in fringing reef environments abstract the steep offshore slope and abrupt transition to a shallow lagoon are conducive to formation of energetic breaking waves in fringing reef environments this paper describes an extension of a one dimensional shock capturing boussinesq type model to account for these processes in two dimensions and the numerical formulation to facilitate adaptive time integration and code parallelization the governing equations contain the conservative form of the nonlinear shallow water equations to capture shock related hydraulic processes the finite volume method with a godunov type scheme provides a compatible conservative numerical procedure a two dimensional tvd total variation diminishing reconstruction procedure evaluates the flow variables on either side of the cell interface while a riemann solver supplies the flux and bathymetry source terms at the interface a well balanced scheme eliminates depth interpolation errors in the domain and preserves continuity across moving boundaries over irregular topography time integration of the governing equations evaluates the conserved variables which in turn provide the horizontal velocity components through systems of linear equations corresponding to series of one dimensional problems the application of the model to fringing reef environments is validated with laboratory experiments performed at oregon state university as well as field data collected in hawaii the model describes the flux dominated wave breaking processes through the riemann solver without predefined empirical energy dissipation and reproduces transitions between sub and supercritical flows as well as development of dispersive and infra gravity waves in the processes