in situ la icp ms trace elements analysis of scheelites from the giant beiya gold polymetallic deposit in yunnan province southwest china and its metallogenic implications abstract the beiya gold polymetallic deposit located in the middle of the jinshajiang ailaoshan alkaline porphyry metallogenic belt is the largest skarn gold deposit in china scheelite is a typical hydrothermal mineral which can serve as mineralization process tracer and is significant for the hydrothermal deposit study in this paper we present in situ la icp ms scheelite geochemical data from the different parts of the skarn mineralization in the beiya deposit the data indicate that the beiya scheelite has high mo average 38 943 ppm and high lree hree average 29 6 resembling typical skarn type scheelite the mechanism of ree substitution of ca in the beiya scheelite was probably 3ca 2 2ree 3 ca which implies that the scheelite inherited its ree composition from magma derived ore forming fluids the scheelite from near the marble shows negative eu anomaly average eu 0 45 indicating an oxidizing condition whereas that from near the porphyry shows positive eu anomaly average eu 3 58 indicating a reducing environment scheelite from the sandstone hosted stratiform orebody shows slight and variable eu anomalies eu 0 66 1 47 indicating possible fluctuating physicochemical conditions our data demonstrate an increasing oxygen fugacity f o 2 trend from the ore related intrusion to the surrounding carbonates at beiya the rb sr nb ta and zr hf ratios of the beiya scheelite suggest an addition of mantle derived components to the ore forming materials of the beiya deposit

formation of au polymetallic ore deposits in alkaline porphyries at beiya yunnan southwest china abstract the beiya gold deposit is located in the central part of the jinshajiang honghe strike slip belt at the junction zone of the tethys himalaya orogenic belt and the yangtze plate in sw china this large scale 125 6 million metric tonnes with a mean grade of 2 42 g t au rich polymetallic deposit is related to alkaline porphyry intrusions previous studies show that the beiya alkaline porphyry intrusions are the fractionation product of a mantle derived magma emplaced in an extension environment at the post collision stage of the india eurasian plate collision the beiya deposit is considered to be skarn related based on detailed field studies and previous work we propose that the beiya porphyry and associated au rich polymetallic ores were formed by the emplacement of magmas within the jinshajiang honghe strike slip fault during the late stage of the india eurasian plate collision at 45 25 ma at beiya the mineralized zones in the cu au rich porphyries are surrounded by au cu fe skarns and au cu veins pb zn ag rich mineralization was derived from the inner porphyry and is widely developed outside the central alkaline rich porphyry the sulfur isotope signature of the sulfide mineralization in the beiya and qinhe deposits is 2 40 4 50 and 1 25 2 75 respectively these values are close to 0 indicating that the sulfur may be mantle derived the 18 o compositions of the ore forming fluids responsible for the formation of calcites at qinhe are 8 10 9 61 which is lower than that of beiya 18 o 10 5 where the ores contain a larger contribution of oxygen from the mantle the beiya porphyry magmas provided fluids and the heat that drove the transport of the metals to the site of deposition alkaline porphyries are widely distributed throughout the jinshajiang honghe strike slip fault belt and they are potential hosts to future discoveries of beiya style mineralization

mineralogy and mineral chemistry of bi minerals constraints on ore genesis of the beiya giant porphyry skarn gold deposit southwestern china abstract the beiya deposit located in the sanjiang tethyan tectonic domain sw china is the third largest au deposit in china 323 t au 2 47 g t as a porphyry skarn deposit beiya is related to cenozoic himalayan alkaline porphyries abundant bi minerals have been recognized from both the porphyry and skarn ores comprising bismuthinite bi cu sulfosalts emplectite wittichenite bi pb sulfosalts galenobismutite cosalite bi ag sulfosalt matildite bi cu pb sulfosalts bismuthinite derivatives bi pb ag sulfosalts lillianite homologs galena matildite series and bi chalcogenides tsumoite the unnamed bi 2 te the unnamed ag 4 bi 3 te 3 tetradymite and the unnamed bi pb 3 te s 4 native bismuth and maldonite are also found in the skarn ores the arsenopyrite geothermometer reveals that the porphyry au mineralization took place at temperatures in the range of 350 450 c and at log f s 2 in the range of 8 0 to 5 5 respectively in contrast the beiya bi mineral assemblages indicate that the skarn ore forming fluids had minimum temperatures of 230 175 c prevailing temperatures exceeding 271 c and fluctuating f s 2 f te 2 conditions we also model a prolonged skarn au mineralization history at beiya including at least two episodes of bi melts scavenging au we thus suggest that this process was among the most effective au enrichment mechanisms at beiya

searching at the right time of day evidence for aqueous minerals in columbus crater with tes and themis data the primary objective of the thermal emission imaging system themis experiment which has been in orbit at mars since early 2002 is to identify minerals associated with hydrothermal and subaqueous environments data from themis have supported the presence of clays silica rich deposits and chlorides but has not before provided definitive evidence for the presence of sulfates this is an especially puzzling result given that sulfates have been extensively identified with other instruments at mars if present sufficiently exposed and in high enough abundances such minerals should be detectable in orbital thermal infrared spectra at the resolution of themis the extended mission proposal for themis on mars odyssey suggests that the detection of all minerals may be enhanced by observing at an earlier time of day and thus at warmer temperatures therefore in 2009 odyssey moved to an earlier orbit time here we examine themis data collected when the earlier orbit time coincided with the martian local southern late summer ls 270 for columbus crater where compact reconnaissance imaging spectrometer for mars crism data have detected a number of aqueous minerals some of the warmest themis images show evidence for aqueous minerals although not in the same locations where crism finds the highest concentrations several factors contribute to this result including differences in the diurnal temperature curve and levels of induration and particle size for themis earlier time of day and proper seasonal observations combine to provide warm surface temperatures and ideal low atmospheric opacity that significantly increases the ability to definitively identify low spectral contrast aqueous minerals at the surface of mars

magnetite melt hfse partitioning abstract results from doped hydrous experiments on natural mafic to intermediate composition lavas at 2 5 kbar pressure were combined with existing 1 atm data to evaluate the effects of composition and temperature on the partitioning behavior of the high field strength elements hfse zr nb ta and hf between magnetite and natural silicate melts magnetite composition was found to be the strongest controlling factor on partitioning behavior the partition coefficients d for zr nb hf and ta correlate with d ti ti and al content of the magnetite temperature and pressure the partition coefficients for the hfse are similar to one another for any given magnetite melt pair but range from 2 in titanomagnetite in addition the relationship between ti and the hfse changes as a function of pressure and temperature with the hfse becoming more incompatible relative to ti at lower temperatures and or higher pressures this change in the relationship between d ti and d hfse with temperature and pressure means that the expressions presented in nielsen et al 1994 nielsen r l forsythe l m gallaghan w e fisk m r 1994 major and trace element magnetite melt partitioning chem geol 117 167 191 are not valid for hydrous aluminous systems expressions were derived to describe the relationship between d hfse and temperature pressure fe 2 mg exchange ti al ratio of the magnetite and d ti these expressions reproduce the input data within 35 50 1 over a range extending from highly incompatible to compatible

chloride bearing materials in the southern highlands of mars chlorides commonly precipitate during the evaporation of surface water or groundwater and during volcanic outgassing spectrally distinct surface deposits consistent with chloride bearing materials have been identified and mapped using data from the 2001 mars odyssey thermal emission imaging system these deposits are found throughout regions of low albedo in the southern highlands of mars geomorphologic evidence from orbiting imagery reveals these deposits to be light toned relative to their surroundings and to be polygonally fractured the deposits are small

geochronology of the giant beiya gold polymetallic deposit in yunnan province southwest china and its relationship with the petrogenesis of alkaline porphyry abstract the beiya gold polymetallic deposit located at the junction of the sanjiang tethys himalaya orogenic belt and the yangtze craton in southwestern china is the largest gold deposit in the region mineralization mainly occurs in skarn which formed along the contacts between porphyry intrusions and limestone host rocks the ore formation process is suggested to be closely related to the himalayan age alkaline porphyries u pb dating of magmatic zircons from the beiya quartz syenite porphyry yields a weighted average 206 pb 238 u ages of 36 07 0 43 ma n 25 mswd 1 17 calculated isochron age of five molybdenite samples from beiya is 34 7 1 6 ma mswd 0 99 initial 187 os of 0 21 0 16 ppb which indicates that mineralization is coeval with the intrusion of the beiya alkaline porphyry this age is also in agreement with the results of apatite fission track analysis in the porphyry magmatic zircon e hf t values range from 7 4 to 0 1 which correspond to the two stage hf model with ages between 1112 ma and 1588 ma this finding suggests that the main source of porphyry was probably melting of thickened mesoproterozoic lower crust triggered by partial melting of the lithospheric mantle zircon ce iv ce iii ratios of ore related porphyry are high given that all eu n eu n ratios are above 0 4 which demonstrates that the magma source of the porphyry was highly oxidized which was favorable for cu au mineralization the medium re concentrations in molybdenite re 2 08 20 54 ppm suggest that the ore forming materials were characterized by mixed crustal mantle sources mineralization in the beiya deposit was one of the many metallogenic events related to the india eurasia collision that was responsible for the fertile deep sourced magmatism

geochemistry of magnetite from porphyry cu and skarn deposits in the southwestern united states a combination of petrographic observations laser ablation inductively coupled plasma mass spectrometry la icp ms and statistical data exploration was used in this study to determine compositional variations in hydrothermal and igneous magnetite from five porphyry cu mo and skarn deposits in the southwestern united states and igneous magnetite from the unmineralized granodioritic inner zone batholith japan the most important overall discriminators for the minor and trace element chemistry of magnetite from the investigated porphyry and skarn deposits are mg al ti v mn co zn and ga of these the elements with the highest variance for i igneous magnetite are mg al ti v mn zn for ii hydrothermal porphyry magnetite are mg ti v mn co zn and for iii hydrothermal skarn magnetite are mg ti mn zn and ga nickel could only be detected at levels above the limit of reporting lor in two igneous magnetites equally cr could only be detected in one igneous occurrence copper as mo ag au and pb have been reported in magnetite by other authors but could not be detected at levels greater than their respective lors in our samples comparison with the chemical signature of igneous magnetite from the barren inner zone batholith japan suggests that v mn co and ga concentrations are relatively depleted in magnetite from the porphyry and skarn deposits higher formation conditions in combination with distinct differences between melt and hydrothermal fluid compositions are reflected in al ti v and ga concentrations that are on average higher in igneous magnetite than in hydrothermal magnetite including porphyry and skarn magnetite low ti and v concentrations in combination with high mn concentrations are characteristic features of magnetite from skarn deposits high mg concentrations 1 000 ppm are characteristic for magnetite from magnesian skarn and likely reflect extensive fluid rock interaction in porphyry deposits hydrothermal magnetite from different vein types can be distinguished by varying ti v mn and zn contents titanium and v concentrations are highly variable among hydrothermal and igneous magnetites but ti concentrations above 3 560 ppm could only be detected in igneous magnetite and v concentrations are on average lower in hydrothermal magnetite the highest ti concentrations are present in igneous magnetite from gabbro and monzonite the lowest ti concentrations were recorded in igneous magnetite from granodiorite and granodiorite breccia and largely overlap with ti concentrations found in hydrothermal porphyry magnetite magnesium and mn concentrations vary between magnetite from different skarn deposits but are generally greater than in hydrothermal magnetite from the porphyry deposits high mg and low ti and v concentrations characterize hydrothermal magnetite from magnesian skarn deposits and follow a trend that indicates that magnetite from skarn calcic and magnesian commonly has low ti and v concentrations

hydrated silicate minerals on mars observed by the mars reconnaissance orbiter crism instrument phyllosilicates a class of hydrous mineral first definitively identified on mars by the omega observatoire pour la mineralogie l eau les glaces et l activitie instrument preserve a record of the interaction of water with rocks on mars global mapping showed that phyllosilicates are widespread but are apparently restricted to ancient terrains and a relatively narrow range of mineralogy fe mg and al smectite clays this was interpreted to indicate that phyllosilicate formation occurred during the noachian the earliest geological era of mars and that the conditions necessary for phyllosilicate formation moderate to high ph and high water activity were specific to surface environments during the earliest era of mars s history here we report results from the compact reconnaissance imaging spectrometer for mars crism of phyllosilicate rich regions we expand the diversity of phyllosilicate mineralogy with the identification of kaolinite chlorite and illite or muscovite and a new class of hydrated silicate hydrated silica we observe diverse fe mg oh phyllosilicates and find that smectites such as nontronite and saponite are the most common but chlorites are also present in some locations stratigraphic relationships in the nili fossae region show olivine rich materials overlying phyllosilicate bearing units indicating the cessation of aqueous alteration before emplacement of the olivine bearing unit hundreds of detections of fe mg phyllosilicate in rims ejecta and central peaks of craters in the southern highland noachian cratered terrain indicate excavation of altered crust from depth we also find phyllosilicate in sedimentary deposits clearly laid by water these results point to a rich diversity of noachian environments conducive to habitability

low temperature aqueous alteration of basalt mineral assemblages of deccan basalts and implications for mars spectra of basalt samples were dominated by fe 2 crystal field transitions with weak alteration bands near 1 4 and or 1 9 mm reststrahlen bands in mid infrared showed the convolution of plagioclase and pyroxene features typical of basalts saprolite samples were incompletely leached and their spectra were dominated by complex al and fe mg bearing smectite clays and retained no original mafic signatures xrd and mossbauer detected pyroxene and plagioclase not visible by reflectance spectroscopy in some saprolite samples zeolites were present throughout the saprolite the laterite was the most leached horizon and all analyses showed kaolinite and iron oxide assemblages this kaolinite and hematite association would be expected if kaolinite on mars formed through leaching under conditions similar to those on earth and has implications for abundant freshwater on the martian surface

in situ geochemistry and fe o isotopic composition of iron oxides from the pha lek fe deposit northwest truong son orogenic belt laos implications for ore forming processes the pha lek fe polymetallic deposit in the southwest of the truong son orogenic belt records the evolution and metallogenesis of the southeastern asia tethys debates remain on the roles the late triassic volcanism played in the formation of the iron oxides of the deposit petrographic and sem studies led to the recognition of two dominant iron oxides magnetite and hematite and three stages of mineralization pre ore syn ore and post ore stages in situ la icp ms analyses for trace elements and fe and o isotopic analyses were applied to understand the origin of the iron oxides generally iron oxide of the syn ore stage has higher total trace elements than post ore stage and magnetite has higher lithophile elements whereas hematite has higher chalocophile elements the trace element abundance in magnetite is most comparable to porphyry skarn hydrothermal magnetite and hematite is more comparable to supergene and secondary non magmatic hydrothermal chemistry all 56fe values of the iron oxide separates are above 0 and have an igneous signature and syn ore stage magnetite has relatively higher 56fe values than the post ore stage hematite all 18o values of the iron oxide separates are below 1 and plot within the non igneous field and show a similar decreasing trend from syn ore stage magnetite to post ore stage hematite we propose that the triassic volcanic activities played a limited role during the mineralization process the deposit was formed because of the late carboniferous early permian porphyry skarn related magmatic hydrothermal alteration and the mixing of non magmatic fluid and or the supergene weathering caused the wide reprecipitation of fe oxides an evolutionary mineralization model related to the low angle subduction for the deposit is also proposed

magnetite compositions from the baba ali iron deposit in the sanandaj sirjan zone western iran implications for ore genesis abstract the economically significant baba ali iron ore deposit is located in the sanandaj sirjan zone western iran is associated with diorite the mineralization trends in a ene wsw direction with thickness that varies from 30 m up to 50 m and a length of about 250 m the main mineral assemblages are massive magnetite epidote actinolite tourmaline quartz calcite and pyrite using different magnetite compositional discrimination diagrams the low concentrations of ti 0 11 wt al 0 06 wt cr 19 62 ppm and co 20 26 and high ni cr ratios 6 34 are consistent with a hydrothermal origin similar to typical skarn mineralization the different elemental compositions of various magnetite generations might be due to an ore forming fluid that initially a high t magmatic hydrothermal character then evolved to a lower temperture meteoric water dominated system it seems that fe bearing saline fluids infiltrated the carbonate host rocks causing high temperature acid metalliferous fluids to become neutralized during reaction with carbonates causing a decrease in iron solubility and saturating as a magnetite with increasing ph and decreasing the temperature the close spatial and temporal association of the mineralization with the fracture systems suggests that a pressure decrease also had a significant impact on the iron solubility triggering ore precipitation and replacement at relatively low temperatures 300 c under reducing conditions

experimental vnir reflectance spectroscopy of gypsum dehydration investigating the gypsum to bassanite transition the spectral behavior of gypsum dehydration in the visible to near infrared 350 2500 nm wavelength range was investigated by partially dehydrating the four main habits of gypsum alabaster satin spar selenite and massive to form bassanite powdered samples of gypsum dehydrated at 100 115 c and hand samples dehydrated at 115 130 c coinciding with a peak in mass water loss in the samples as gypsum dehydrates its characteristic h2o absorption bands at 1443 and 1945 nm shift to shorter wavelengths band depths and widths of absorptions at 1200 1400 1600 1750 1945 2100 2200 and 2400 nm all decrease with increasing temperature the samples also underwent visible changes upon dehydration both at the macroscopic and microscopic level becoming very friable with an increase in fine grains no consistent relationship was observed between dehydration temperature and grain size or habit the samples were monitored for up to 20 months after dehydration during which time none rehydrated to form gypsum while the transition from gypsum to bassanite is very abrupt bassanite does not readily rehydrate to form gypsum again in ambient conditions and therefore may not be as unstable as previously thought by terrestrial occurrences of bassanite being predominantly restricted to hyperarid climates

reflectance spectroscopy and optical functions for hydrated fe sulfates visible and near infrared wavelength vnir 0 35 5 m laboratory diffuse reflectance spectra and corresponding optical functions real and imaginary refractive indices for several iron sulfates natural k and na jarosite szomolnokite rhomboclase are presented on mars jarosite has been identified in meridiani planum mawrth vallis melas chasma and eridania basin szomolnokite has been found as distinct layers at columbus crater and as outcrops at juventae chasma and rhomboclase has been identified at gusev crater constraining the mineralogy and chemistry fe vs mg rich of the sulfates on mars may contribute to our understanding of the environmental and aqueous conditions present on mars during their formation the data presented here will help to constrain the mineralogy abundance and distribution of sulfates on the martian surface which will lead to improvements in understanding the pressure temperature and humidity conditions and how active frost groundwater and atmospheric processes once were on mars

trace elements in magnetite as petrogenetic indicators we have characterized the distribution of 25 trace elements in magnetite mg al si p ca sc ti v cr mn co ni cu zn ga ge y zr nb mo sn hf ta w and pb using laser ablation icp ms and electron microprobe from a variety of magmatic and hydrothermal ore forming environments and compared them with data from the literature we propose a new multielement diagram normalized to bulk continental crust designed to emphasize the partitioning behavior of trace elements between magnetite the melt fluid and co crystallizing phases the normalized pattern of magnetite reflects the composition of the melt fluid which in both magmatic and hydrothermal systems varies with temperature thus it is possible to distinguish magnetite formed at different degrees of crystal fractionation in both silicate and sulfide melts the crystallization of ilmenite or sulfide before magnetite is recorded as a marked depletion in ti or cu respectively the chemical signature of hydrothermal magnetite is distinct being depleted in elements that are relatively immobile during alteration and commonly enriched in elements that are highly incompatible into magnetite e g si and ca magnetite formed from low temperature fluids has the lowest overall abundance of trace elements due to their lower solubility chemical zonation of magnetite is rare but occurs in some hydrothermal deposits where laser mapping reveals oscillatory zoning which records the changing conditions and composition of the fluid during magnetite growth this new way of plotting all 25 trace elements on 1 diagram normalized to bulk continental crust and elements in order of compatibility into magnetite provides a tool to help understand the processes that control partitioning of a full suit of trace elements in magnetite and aid discrimination of magnetite formed in different environments it has applications in both petrogenetic and provenance studies such as in the exploration of ore deposits and in sedimentology

in situ la icp ms trace elemental analyses of magnetite the mesozoic tengtie skarn fe deposit in the nanling range south china abstract the nanling range in south china hosts numerous world class w sn deposits and some fe deposits the mesozoic tengtie fe skarn deposit in the southern nanling range is contemporaneous with the regional sn mineralization the deposit is composed of numerous ore bodies along the contacts between the late paleozoic or mesozoic carbonate rocks and the yanshanian lianyang granitic complex interaction of the magma with hosting dolomitic limestone and limestone formed calcic ca rich and magnesian mg rich skarns respectively the tengtie deposit has a paragenetic sequence of the prograde stage of anhydrous skarn minerals followed by the retrograde stage of hydrous skarn minerals and the final sulfide stage magnetite in the prograde and retrograde skarn stages is associated with diopside garnet chlorite epidote and phlogopite whereas magnetite of the final stage is associated with chalcopyrite and pyrite massive magnetite ores crosscut by quartz and calcite veins are present mainly in the retrograde skarn stage laser ablation icp ms was used to determine trace elements of magnetite from different stages some magnetite grains have unusually high ca na k and si possibly due to the presence of silicate mineral inclusions magnetite of the prograde stage has the highest co contents but that of the sulfide stage is extremely poor in co which partitions in sulfides magnetite of magnesian skarns contains more mg mn and al than that of calcic skarns attributed to the interaction of the magma with compositionally different host rocks magnetite from calcic and magnesian skarns contains 6 185 ppm sn and 61 1246 ppm sn respectively the high sn contents are not due to the presence of cassiterite inclusions which are not identified in magnetite instead we believe that sn resides in the magnetite structure regionally intensive mesozoic sn mineralization in south china indicates that concurrent magmatic hydrothermal fluids may be rich in sn and contribute to the formation of high sn magnetite our study demonstrates that trace elements of magnetite can be a sensitive indicator for the skarn stages and wall rock compositions and as such trace elemental chemistry of magnetite can be a potentially powerful fingerprint for sediment provenance and regional mineralization

trace elements in magnetite from porphyry cu mo au deposits in british columbia canada abstract this study examines trace elements in hydrothermal magnetite from five porphyry cu mo au deposits and two skarns in british columbia canada trace element concentrations vary several orders of magnitude both within and between magnetite from skarn and porphyry deposit settings the heterogeneous composition of hydrothermal magnetite may in part be due to the short duration low temperature and multiple fluid events that attend the formation of porphyry ore deposits principal component analysis shows two dominant patterns of trace element abundances in hydrothermal magnetite firstly positive correlations of ti al and v which account for nearly 40 of the total variation in magnetite are inferred to depend on temperature and oxygen fugacity secondly antithetic abundances of lower valence cations co mn with higher valence cations sn and mo may reflect variations in the redox potential acidity and metal speciation of hydrothermal fluids the cu fe and mn fe ratios calculated for fluids in equilibrium with the hydrothermal magnetite using experimental partitioning data are similar to those measured directly in brines trapped in quartz hosted fluid inclusions from porphyry cu mo au deposits

steady state behaviour of the black ven mudslide the application of archival analytical photogrammetry to studies of landform change the concept of dynamic equilibrium has provided geomorphologists with a challenging paradigm for studying landform evolution but quantitative evidence for its existence has proved illusive particularly for complex geomorphological systems the authors believe that the principle has now been verified through the application of the archival photogrammetric technique to a sequence of historical photographs spanning 50 years of process at the black ven mudslide complex in dorset u k the principles and limitations of the archival photogrammetric technique are described the method is applied to oblique and vertical aerial photographs of black ven at five epochs commencing in 1946 continuing at approximately 10 year intervals until 1988 the technique is used to generate plans contours sections and a dense and accurate digital elevation model dem of the whole site at each epoch this is used to generate dems of difference and a distribution of slope angle which suggest that the mudslides are in equilibrium despite the removal of 200 000 m3 of sediment between 1958 and 1988 extrapolation of the slope distribution through time suggests that the frequency of an episodic landform change model at black ven may be approximately 60 years

reconstruction of former glacier surface topography from archive oblique aerial images abstract archive oblique aerial imagery offers the potential to reconstruct the former geometry of valley glaciers and other landscape surfaces whilst the use of structure from motion sfm photogrammetry with multiview stereopsis mvs to process small format imagery is now well established in the geosciences the potential of the technique for extracting topographic data from archive oblique aerial imagery is unclear here sfm mvs is used to reconstruct the former topography of two high arctic glaciers midtre and austre lovenbreen svalbard norway using three archive oblique aerial images obtained by the norwegian polar institute in 1936 the 1936 point cloud was produced using seven lidar derived ground control points located on stable surfaces in proximity to the former piedmont glacier termini to assess accuracy the 1936 data set was compared to a lidar data set using the m3c2 algorithm to calculate cloud to cloud differences for stable areas such as nonglacial surfaces vertical differences were detected between the two point clouds rms m3c2 vertical difference of 8 5 m with the outwash zones adjacent to the assessed glacier termini showing less extensive vertical discrepancies 94 of m3c2 vertical differences between 5 m this research highlights that historical glacier surface topography can be extracted from archive oblique aerial imagery but accuracy is limited by issues including the lack of camera calibration the quality and resolution of the archive imagery and by the identification of suitable ground control to demonstrate the value of historical glacier surfaces produced using oblique archive imagery the reconstructed glacier surface topography is used to investigate evidence of a potential former surge front at the high arctic valley glacier austre lovenbreen a glacier identified to have potentially exhibited surge type behaviour during the neoglacial a surface bulge of 15 20 m is resolved on the 1936 model however when compared with the now deglaciated former subglacial topography a surge origin for the surface feature becomes unclear the processed 1936 oblique imagery was also used to produce orthorectified nadir aerial imagery from which structural mapping was undertaken this adds to the existing 1948 1995 structural map series for these glaciers this research demonstrates the potential of sfm mvs for reconstructing historical glacier surfaces which is important for aiding our understanding of former glacier dynamics and enabling the rapid assessment of glacier change over time

evaluation of dsms generated from multi temporal aerial photographs using emerging structure from motion multi view stereo technology abstract an accuracy assessment of digital surface models dsms generated from archived aerial photographs using the structure from motion multi view stereo sfm mvs technique was carried out a four step accuracy assessment procedure was adopted using aerial photography from eight periods as follows step 1 generate a dsm and orthophoto from digital aerial photographs taken in 2013 and ground control points gcps measured by gnss step 2 assess the accuracy of the dsm by comparison with altitude measured by leveling survey step 3 generate other historical dsms and orthophotos from historical aerial photographs using gcps extracted from the dsm of 2013 step 4 assess the accuracy of all historical dsms by comparing with the leveling survey then re calculate the accuracy of historical dsms by reducing the inherent error in the 2013 dsm the dsm based on the aerial photographs taken in 2013 was generated with a resolution of 48 2 cm the residual height error of the gcps was 15 4 cm validation against the altitudes of 171 points revealed that this dsm has a height root mean square error rmse of 24 1 cm and is 9 2 cm lower than the leveling data on average even using us military photos with unconfirmed detailed specifications the model can measure the altitude with an rmse value of 121 5 cm it appears therefore that analysis by sfm mvs can give comparable measurement accuracy to traditional aerial photogrammetry the low cost and high accuracy obtained with archived aerial photographs are worthy of special mention

in situ la icp ms trace elements analysis of magnetite the fenghuangshan cu fe au deposit tongling eastern china abstract the fenghuangshan deposit is a typical cu fe au skarn deposit in the tongling area anhui province eastern china the deposit has a paragenetic sequence of a prograde skarn stage followed by a retrograde skarn stage and a final quartz sulfide and carbonate stages magnetite in the fenghuangshan deposit mainly formed in the retrograde and carbonate stages according to the morphology of magnetite and mineral assemblage of ores we divided magnetite bearing ores into three groups group 1 early retrograde skarn stage is represented by a mineral assemblage of magnetite and chalcopyrite group 2 late retrograde skarn stage has a mineral assemblage of magnetite chalcopyrite and wollastonite with characteristic ring like magnetite group 3 carbonate stage is characterized by large amounts of calcite veins crosscut or associated with magnetite and intensive hematization of magnetite crosscut by the veins laser ablation la icp ms was used to determine trace element concentrations of magnetite from the three mineralization stages positive correlations among mg al ca and si in magnetite indicate that these lithophile elements have similar behavior during the skarn formation process calcium is an important discriminant element for magnetite in skarn deposits positive correlations are also evident for pb sn and w in magnetite which also indicates their similar behavior in general magnetite grains of different stages have similar normalized trace element patterns indicating that they share a common source however some elements such as co and mn in magnetite decrease from early retrograde skarn stage late retrograde skarn stage to carbonate stage which may be attributed to the precipitation of coexisting minerals sulfides and carbonates or the decreasing temperature magnetite grains of the retrograde stage have higher mg mn and si al contents than those of the carbonate stage indicating a decreasing degree of fluid rock interaction during the skarn formation process trace element data of skarn magnetite indicate a more widely compositional variation than previously suggested magnetite from the fenghuangshan cu fe au deposit has similar composition to those from other cu cu fe or cu polymetallic skarn deposits but different from those from fe skarn deposits such that magnetite composition is very powerful in establishing the origin of skarn deposits

monitoring and modelling morphological change in a braided gravel bed river using high resolution gps based survey recent research in fluvial geomorphology has emphasized the direct monitoring of channel topography as a useful tool to better understand the interrelationship between river form and process and in particular to estimate bedload transport rates and reach scale sediment budgets until recently however this morphometric approach has been limited to comparison of repeatedly surveyed cross sections with the associated problems of low frequency sampling and an emphasis on cross stream as opposed to downstream morphological dynamics recent advances in analytical photogrammetry have however permitted the acquisition of data at sufficient resolutions to represent macroform 101 m and microform 10 m channel geometry in fully three dimensions while inherently spatially distributed the photogrammetric approach to land surveying is however restricted to observable areas of the channel and is thus of limited use in the subaqueous zone especially if flows are turbid or highly coloured this paper presents an alternative approach to the study of three dimensional morphological dynamics of a divided reach of the gravelly river feshie scotland in which topographic survey of both exposed and submerged areas of the reach was undertaken using the global positioning system gps survey results from two field programmes in 1998 and 1999 are presented in which a geotronics geotracer 2000 real time kinematic gps receiving unit was used to survey a 200 80 m reach rapid radial survey methods were employed permitting the collection of 2000 survey points per day giving a mean density over the 13 ha reach of 1 1 points per square metre a detailed assessment of survey errors and dem quality is presented and a limit of detection of c 10 cm proposed as an upper threshold for the identification of significant change between dems preliminary interpretation of channel dynamics in 1998 99 reveals relatively little change to the overall macroscale reach structure dem differencing techniques however highlight important local changes including the progradation of submerged bar fronts bar head aggradation and scour along major channel thalwegs and the erosion of fines from sloughs copyright 2000 john wiley sons ltd

optimizing photogrammetric dems for glacier volume change assessment using laser scanning derived ground control points photogrammetric processing of archival stereo imagery offers the opportunity to reconstruct glacier volume changes for regions where no such data exist and to better constrain the contribution to sea level rise from small glaciers and ice caps the ability to derive digital elevation model dem measurements of glacier volume from photogrammetry relies on good quality well distributed ground reference data which may be difficult to acquire this study shows that ground control points gcps can be identified and extracted from point cloud airborne lidar data and used to control photogrammetric glacier models the technique is applied to midtre lovenbreen a small valley glacier in northwest svalbard we show that the amount of ground control measured and the elevation accuracy of gcp coordinates based on known and theoretical error considerations has a significant effect on photogrammetric model statistics dem accuracy and the subsequent geodetic measurement of glacier volume change models controlled with fewer than 20 lidar control points or gcps from sub optimal areas within the swath footprint overestimated volume change by 14 53 over a 2 year period dems derived from models utilizing 20 25 or more gcps however gave volume change estimates within 4 of those from repeat lidar data 0 51 m a 1 between 2003 and 2005 our results have important implications for the measurement of glacier volume change from archival stereo imagery sources

digital photogrammetry and gis based analysis of the bio geomorphological evolution of sakurajima volcano diachronic analysis from 1947 to 2006 abstract the sakurajima volcano is one of the most active volcanoes in the world with regular activity dominated by vulcanian eruptions since 1955 located in kagoshima prefecture kyushu island japan the sakurajima volcano is a stratovolcano with two main vents at the summit the kitadake and the minamidake and a third smaller central vent the nakadake the two firsts peak at 1117 and 1060 m dominate the slopes mainly composed of lava flow deposits secondary volcaniclastic material and recent ejectas from the vulcanian eruptions although the volcano has been very closely monitored by japanese universities mostly kyoto university and kagoshima university and governmental agencies there has been very little geomorphological investigation of the structure of the volcano using the digital photogammetric method sfm mvs structure from motion and multiple view stereophotogrammetry applied to historical aerial photographs the present contribution aims to provide an analysis of the volcanic structure and the recent bio geomorphological evolution for the period 1947 2006 first the results have proved that sfm mvs is a method that can be successfully applied to aerial photographs for diachronic reconstruction of geomorphological landscape evolution this method is especially important in active volcanic areas as the geomorphology can change very rapidly within the historical period secondly the results have shown that during the last 60 years the summit area of the sakurajima has greatly evolved the morpholology of the minamidake crater has changed due to its regular explosive activity the upper slopes have been covered in ejecta modifying their elevation and their smoothness the lower slopes have seen the apparition of lahar deposition areas while valleys upslope have widened due to the lahar activity and the upward progression of the deposits the 3d derived from sfm mvs has also shown how the lahar deposits are using the topographic low created on top of the lava deposits and in between lava deposit to accumulate mid slopes rather than accumulating on the lower volcanic apron this is accentuated by the construction of sabo dams that keep a large amount of the material on the slopes finally as this publication has been carried out using the freely available imagery from the gsi geospatial information authority of japan at 200 dpi higher resolution imagery can even open further possibilities for the monitoring of volcano evolution in japan and in countries providing long series of historical imagery

re os isotopic ages of pyrite and chemical composition of magnetite from the cihai magmatic hydrothermal fe deposit nw china the eastern tianshan orogenic belt of the central asian orogenic belt and the beishan terrane of the tarim block nw china host numerous fe deposits the cihai fe deposit 90 mt at 45 6 fe in the beishan terrane is diabase hosted and consists of the cihai cinan and cixi ore clusters ore minerals are dominantly magnetite pyrite and pyrrhotite with minor chalcopyrite galena and sphalerite gangue minerals include pyroxene garnet hornblende and minor plagioclase biotite chlorite epidotite quartz and calcite pyrite from the cihai and cixi ore clusters has similar re os isotope compositions with 14 to 62 ppb re and 10 ppt common os pyrrhotite has 5 to 39 ppb re and 0 6 ppb common os pyrite has a mean re os model age of 262 3 5 6 ma n 13 in agreement with the isochron regression of 187os vs 187re the re os age 262 ma for the cihai fe deposit is within uncertainty in agreement with a previously reported rb sr age 268 25 ma of the hosting diabase indicating a genetic relationship between magmatism and mineralization magnetite from the cihai deposit has mg al ti v cr co ni mn zn ga and sn more elevated than that of typical skarn deposits but both v and ti contents lower than that of magmatic fe ti v deposits magnetite from these two ore clusters at cihai has slightly different trace element concentrations magnetite from the cihai ore cluster has relatively constant trace element compositions some magnetite grains from the cixi ore cluster have higher v ti and cr than those from the cihai ore cluster the compositional variations of magnetite between the ore clusters are possibly due to different formation temperatures combined with regional tectonic evolution of the beishan terrane the re os age of pyrite and the composition of magnetite indicate that the cihai fe deposit may have derived from magmatic hydrothermal fluids related to mafic magmatism probably in an extensional rift environment

ice cored moraine degradation mapped and quantified using an unmanned aerial vehicle a case study from a polythermal glacier in svalbard ice cored lateral frontal moraines are common at the margins of receding high arctic valley glaciers but the preservation potential of these features within the landform record is unclear recent climatic amelioration provides an opportunity to study the morphological evolution of these landforms as they de ice this is important because high arctic glacial landsystems have been used as analogues for formerly glaciated areas in the mid latitudes this study uses sfm structure from motion photogrammetry and a combination of archive aerial and uav unmanned aerial vehicle derived imagery to investigate the degradation of an ice cored lateral frontal moraine at austre lovenbreen svalbard across the study area as a whole over an 11 year period the average depth of surface lowering was 1 75 0 89 m the frontal sections of the moraine showed low or undetectable rates of change spatially variable rates of surface lowering are associated with differences in the quantity of buried ice within the structure of the moraine morphological change was dominated by surface lowering with limited field evidence of degradation via back wastage this permits the moraine a greater degree of stability than previously observed at other sites in svalbard it is unclear whether the end point will be a fully stabilised ice cored moraine in equilibrium with its environment or an ice free lateral frontal moraine complex controls on geomorphological change e g topography and climate and the preservation potential of the lateral frontal moraine are discussed the methods used by this research also demonstrate the potential value of sfm photogrammetry and unmanned aerial vehicles for monitoring environmental change and are likely to have wider applications in other geoscientific sub disciplines

ground penetrating radar measurements of subsurface structures of lacustrine sediments in the qaidam basin nw china possible implications for future in situ radar experiments on mars abstract the stratigraphic profile of paleolakes on mars preserves a record of past climatic hydrological and sedimentary environment radar could be used to detect the structure and distribution of buried lacustrine sediments but orbiter radar sounders rarely detect the internal structure or the bottom of the ancient martian lake deposits future martian missions will employ ground penetrating radar gpr onboard rovers to investigate the shallow subsurface structure of paleolake basins in this case ground experiments are necessary to test the potential of gpr detection this study reports on gpr experiments operating at 100 mhz and 200 mhz carried out in the qaidam basin one of the analogue sites for martian paleolake environments to detect the subsurface structure of lacustrine sediments and measure the relative permittivity of sediments with both laboratory instrument and gpr data two gpr measurements were performed on top of yardangs representing layered lacustrine sedimentary outcrops another survey site is a polygonal patterned ground which is a common landform in the qaidam basin and on mars the observations revealed by gpr experiments show that 1 sediments of three sites have varied compositions density and porosity and have a wide range of relative permittivity values from 1 56 to 4 56 2 the detection depth of our measurements could reach 20 m 3 the interfaces between sedimentary layers can be seen in radargrams but reflectors in radargrams may not always match with exposed layers of the yardang outcrops due to the undetected change of permittivity values or thin thickness of layers 4 a distinct and continuous reflector is observed beneath the polygonal terrain which we interpret as a subsurface layer with low water brine content our ground experiments suggest that a similar gpr on martian rover could detect the near surface structure of lacustrine sediments e g deposition anomaly interfaces of drastic permittivity change such as buried ice brine considering that the design frequency is close to our equipment

in situ la icp ms trace elemental analyses of magnetite cu au fe deposits in the khetri copper belt in rajasthan province nw india abstract magnetite is common in many ore deposits and their host rocks and is useful for petrogenetic studies in the khetri copper belt in rajasthan province nw india there are several cu au fe deposits associated with extensive cu fe au ag co ree u mineralization hosted in phyllites schists and quartzites of the paleoproterozoic delhi supergroup ore bodies of these deposits comprise dominantly disseminated and vein type cu sulfide ores composed of chalcopyrite pyrite and pyrrhotite intergrown with minor magnetite there are also fe oxide ores with minor or no cu sulfides which are locally overprinted by the mineral assemblage of the cu sulfide ores in addition to the fe oxide and cu sulfide ores the protolith of the delhi supergroup includes banded iron formations bifs with original magnetite preserved i e magnetite quartzites and their sheared counterparts in the sheared magnetite quartzites their magnetite and quartz are mobilized and redistributed to magnetite and quartz bands trace elemental compositions of magnetite from these types of ores rocks were obtained by la icp ms the dataset indicates that different types of magnetite have distinct concentrations of ti al mg mn v cr co ni zn cu p ge and ga which are correlated to their forming environments magnetite grains in magnetite quartzites have relatively high al 800 8000 ppm ti 150 900 ppm and v 300 600 ppm contents compared to those of bifs in other regions such as the yilgarn craton western australia and labrador canada the high al ti and v contents can be explained by precipitation of the magnetite from relatively reduced al ti rich water possibly involving hotter seafloor hydrothermal fluids derived from submarine mafic volcanic rocks magnetite in sheared magnetite quartzites is generally irregular and re crystallized and has ni mn al cu and p contents lower than the magnetite from the unsheared counterparts suggesting that the shearing related mobilization is able to extract these elements from original magnetite however elevated contents of ti v co cr ge and mg of the magnetite in the sheared magnetite quartzites can be ascribed to involvement of external hydrothermal fluids during the shearing consistent with occurrence of some hydrothermal minerals in the samples compositions of magnetite from the fe oxide and cu sulfide ores are interpreted to be controlled mainly by fluid compositions and or oxygen fugacity f o 2 other potential controlling factors such as temperature fluid rock interaction and co precipitating minerals have very limited impacts magnetite in the cu sulfide ores has higher v but lower ni contents than that of the fe oxide ores likely indicating its precipitation from relatively reduced evolved fluids however it is also indicated that the two types of magnetite do not show large distinctions in terms of concentrations of most elements suggesting that they may have precipitated from a common evolving fluid we propose a combination of ge versus ti al and cr versus co ni co variation plots to discriminate different types of magnetite from the khetri copper belt our work agrees well with previous studies that compositions of magnetite can be potentially useful for provenance studies but also highlights that discrimination schemes would be more meaningful for deposits in a certain region if fluid water chemistry and specific formation conditions reflected in compositions of magnetite are clearly understood

contribution of mafic melt to porphyry copper mineralization evidence from mount pinatubo philippines and bingham canyon utah usa mount pinatubo in the philippines known for its cataclysmic eruption in 1991 hosts several porphyry copper deposits and active geothermal systems an underlying mafic melt supplied much of the sulphur for the dacitic magma and its injection into the dacitic magma chamber triggered the eruption the eruption caused purging of the sulphur rich fluid from the dacite to the atmosphere and extensive fracturing similar events took place at bingham canyon utah site of the largest copper and gold deposit in north america at 38 ma the bingham canyon mineralization took place beneath an active stratovolcano and pyroclastic flows contemporaneous with the mineralization show evidence for magma mingling ascent of mafic melt supplied sulphur and chalcophile elements to the felsic magma which consolidated to form the bingham stock and its underlying magma chamber injections of the mafic melt caused periodic eruptions of felsic magma to form the stratovolcano and deposition of sulphide minerals in highly fractured rocks in and around the stock

dissolution reprecipitation process of magnetite from the chengchao iron deposit insights into ore genesis and implication for in situ chemical analysis of magnetite abstract magnetite formed in different environments commonly has distinct assemblages and concentrations of trace elements that can potentially be used as a genetic indicator of this mineral and associated ore deposits in this paper we present textural and compositional data of magnetite from the chengchao iron deposit daye district china to provide a better understanding in the formation mechanism and genesis of the deposit and shed light on analytical protocols for in situ chemical analysis of hydrothermal magnetite magnetite grains from the ore related granitoid pluton mineralized endoskarn magnetite dominated exoskarn and vein type iron ores hosted in marine carbonate intruded by the pluton were examined using scanning electron microscopy and analyzed for major and trace elements using electron microprobe back scattered electron images reveal that primary magnetite from the mineralized skarns and vein type ores were all partly reequilibrated with late stage hydrothermal fluids forming secondary magnetite domains that are featured by abundant porosity and have sharp contact with the primary magnetite these textures are interpreted as resulting from a dissolution reprecipitation process of magnetite which however are mostly obscure under optically primary magnetite grains from the mineralized endoskarn and vein type ores contain high sio 2 0 92 3 21 wt al 2 o 3 0 51 2 83 wt and low mgo 0 15 0 67 wt whereas varieties from the exoskarn ores have high mgo 2 76 3 07 wt and low sio 2 0 03 0 23 wt and al 2 o 3 0 54 1 05 wt this compositional contrast indicates that trace element geochemical composition of magnetite is largely controlled by the compositions of magmatic fluids and host rocks of the ores that have reacted with the fluids compared to its precursor mineral secondary magnetite is significantly depleted in most trace elements with sio 2 deceasing from 1 87 to 0 47 wt on average and al 2 o 3 from 0 89 to 0 08 wt in mineralized endoskarn and vein type ores and mgo from 2 87 to 0 60 wt in exoskarn ores on the contrary average content of iron is notably increased from 69 2 wt to 71 9 wt in the secondary magnetite grains the results suggest that the dissolution reprecipitation process has been important in significantly removing trace elements from early stage magnetite to form high grade high quality iron ores in hydrothermal environments the textural and compositional data confirm that the chengchao iron deposit is of hydrothermal origin rather than being crystallized from immiscible iron oxide melts as previously suggested this study also highlights the importance of textural characterization using various imaging techniques before in situ chemical analysis of magnetite as is the case for texturally complicated u th bearing accessory minerals that have been widely used for u pb geochronology study

the geology and mineralogy of the beiya skarn gold deposit in yunnan southwest china the beiya skarn gold deposit is located in the eastern tethyan orogenic belt in western yunnan province china it is one of the largest gold deposits in china with significant amounts of silver and base metals to the end of 2014 the estimated resources are 125 million tonnes mt of ore grading 2 42 g t au 0 48 wt cu 25 5 wt fe 38 85 g t ag 1 24 wt pb and 0 53 wt zn skarn alteration and mineralization are related to shoshonitic quartz monzonite porphyries that were emplaced in triassic carbonates beiya formation re os dating on molybdenite from a skarn orebody indicates an ore forming age of 36 82 0 48 ma which is consistent with previous dating results of the quartz monzonite porphyries at least two paragenetic stages of skarn minerals and associated sulfides were recognized with the early stage typified by garnet pyroxene magnetite and calcite and the late stage characterized by epidote amphibole chlorite quartz and calcite containing up to 70 sulfides pyrite chalcopyrite and minor pyrrhotite the early skarn is dominated by anhydrous minerals which were replaced by hydrous minerals formed during the late stage the garnet in the beiya deposit is andradite rich ad36 97gr3 61 and pyroxene is relatively diopside rich di8 91hd7 89 this mineral assemblage indicates an oxidized skarn system similar to other au cu fe bearing skarn deposits around the world fluid inclusions from pyroxene indicate precipitation from high temperature and high to moderate salinity fluids 420 530 c 11 1 43 3 wt nacl equiv which probably results from boiling of a moderately saline magmatic fluid cooler 180 365 c and moderate to low salinity fluids 1 6 16 5 wt nacl equiv were trapped in garnet and quartz and are interpreted to be responsible for gold deposition chlorite chemistry indicates ore forming temperatures between 300 and 340 c in agreement with fluid inclusion data it appears that gold was transported as chloride complexes under oxidized conditions and was deposited at temperatures of about 300 c when transport of chloride complexes as gold carriers was less efficient

revised crism spectral parameters and summary products based on the currently detected mineral diversity on mars the investigation of hyperspectral data from the mars reconnaissance orbiter compact reconnaissance imaging spectrometer for mars crism and the observatoire pour la mineralogie l eau les glaces et l activitie omega on mars express has revealed an increasingly diverse suite of minerals present on the martian surface a revised set of 60 spectral parameters derived from corrected spectral reflectance at key wavelengths in crism targeted observations and designed to capture the known diversity of surface mineralogy on mars is presented here as summary products some of the summary products have strong heritage to omega spectral parameter calculations this paper also presents newly derived parameters that highlight locations with more recently discovered spectral signatures type locations for the diversity of currently identified mineral spectral signatures have been compiled into a library presented in this work our analysis indicates that the revised set of summary products captures the known spectral diversity of the surface and successfully highlights and differentiates between locations with differing spectral signatures the revised spectral parameter calculations and related products provide a useful tool for scientific interpretation and for future mission landing site selection and operations

estimation of regional material yield from coastal landslides based on historical digital terrain modelling high resolution historical 1942 and recent 1994 digital terrain models were derived from aerial photographs along the big sur coastline in central california to measure the long term volume of material that enters the nearshore environment during the 52 year measurement time period an average of 21 000 3100 m3 km 1 a 1 of material was eroded from nine study sections distributed along the coast with a low yield of 1000 240 m3 km 1 a 1 and a high of 46 700 7300 m3 km 1 a 1 the results compare well with known volumes from several deep seated landslides in the area and suggest that the processes by which material is delivered to the coast are episodic in nature in addition a number of parameters are investigated to determine what influences the substantial variation in yield along the coast it is found that the magnitude of regional coastal landslide sediment yield is primarily related to the physical strength of the slope forming material coastal highway 1 runs along the lower portion of the slope along this stretch of coastline and winter storms frequently damage the highway the california department of transportation is responsible for maintaining this scenic highway while minimizing the impacts to the coastal ecosystems that are part of the monterey bay national marine sanctuary this study provides environmental managers with critical background data on the volumes of material that historically enter the nearshore from landslides as well as demonstrating the application of deriving historical digital terrain data to model landscape evolution published in 2005 by john wiley sons ltd

bi melt formation and gold scavenging from hydrothermal fluids an experimental study abstract the role of polymetallic melts in scavenging ore components has recently been highlighted in the context of fluid poor metamorphosed ore deposits in contrast the role of polymetallic melts in systems dominated by hydrothermal fluids remains poorly understood using a simple au bi model system we explored experimentally whether such polymetallic melts can precipitate directly from a hydrothermal fluid and investigated the ability of these melts to scavenge au from the solution the experiments were conducted in custom built flow through reactors designed to reproduce a hydrothermal system where melt components are dissolved at one stage along the flow path e g bi was dissolved by placing bi minerals along the fluid path whereas melt precipitation was caused further along the flow path by fluid rock interaction bi rich melts were readily obtained by reaction with pyrrhotite graphite or amorphous fes when au was added to the system bi au melts with compositions consistent with the au bi phase diagram were obtained in the case of fluid reaction with pyrrhotite epitaxial replacement of pyrrhotite by magnetite was observed with textures consistent with an interface coupled dissolution reprecipitation reaction icdrr in this case the metallic melt precipitated as blebs that were localized at the replacement front or within the porous magnetite direct fractionation of bi au melts from a hydrothermal fluid or precipitation of a bi melt followed by partitioning of au from ambient fluid offer new pathways to the enrichment of minor ore components such as au without requiring fluid saturation with respect to a au mineral this mechanism can explain the strong geochemical affinity recognized between au and low melting point chalcophile elements such as bi in many gold deposits examples of deposits where such a model may be applicable include orogenic gold deposits and gold skarns contrary to models involving migration of polymetallic melts to explain element remobilization only small quantities ppm of polymetallic melts are required to affect the au endowment of a deposit via interaction with a hydrothermal fluid the experiments also show that micro environments can play a critical role in controlling melt occurrences for example reaction fronts developing via icdr reactions can promote melt formation as observed during the replacement of pyrrhotite by magnetite the associated transient porosity creates space for the melt and promotes melt fluid exchanges whereas the reaction front provides local geochemical conditions favorable to melt precipitation e g reduced low ah2s aq and catalytic surface

roaming zones of precipitation on ancient mars as recorded in valley networks 1 the 10 largest valley networks in the terra sabaea arabia terra and meridiani planum regions of mars were mapped crater age dated and analyzed by geomorphology stream order and drainage density to understand changes in fluvial erosion during early martian history all of these networks demonstrate characteristics consistent with formation by precipitation many appear to be in different stages of preservation with both highly eroded and pristine valleys sometimes appearing in the same network in some cases the valley network morphologies and crater age dating indicate multiple periods of formation the results from this research place precipitation driven formation of the martian valley networks in terra sabaea arabia terra and meridiani planum in the late noachian and early hesperian epochs 3 6 3 8 billion years ago our age estimates do not extend into earlier or later martian history and the spread in these ages indicates they did not all form or cease formation at the same time the difference in age between the oldest and youngest valley networks in terra sabaea arabia terra and meridiani planum analyzed in this work is 210 50 ma within this range are valley networks that have distinctly separate ages and those that appear to be coeval this research suggests the late noachian and early hesperian were characterized by roaming zones of precipitation that occurred during either continuously warmer and thicker atmospheric conditions or intermittently clement conditions with precipitation occasionally returning to previously rainy regions and overall continuing near meridiani planum longer than in terra sabaea

the potential of small unmanned aircraft systems and structure from motion for topographic surveys a test of emerging integrated approaches at cwm idwal north wales novel topographic survey methods that integrate both structure from motion sfm photogrammetry and small unmanned aircraft systems suas are a rapidly evolving investigative technique due to the diverse range of survey configurations available and the infancy of these new methods further research is required here the accuracy precision and potential applications of this approach are investigated a total of 543 images of the cwm idwal moraine mound complex were captured from a light b5 kg semi autonomous multi rotor unmanned aircraft system using a consumer grade 18 mp compact digital camera the imageswere used to produce a dsm digital surfacemodel of themoraines the dsmis in good agreement with 7761 total station survey points providing a total verticalrmse value of 0 517mand verticalrmse values as lowas 0 200mfor less densely vegetated areas of the dsm high precision topographic data can be acquired rapidly using this technique with the resulting dsms and orthorectified aerial imagery at sub decimetre resolutions positional errors on the total station dataset vegetation and steep terrain are identified as the causes of vertical disagreement whilst this aerial survey approach is advocated for use in a range of geomorphological settings care must be taken to ensure that adequate ground control is applied to give a high degree of accuracy

metallogenic setting and ore genetic model for the beiya porphyry skarn polymetallic au orefield western yunnan china abstract the beiya in western yunnan china is a world class porphyry skarn polymetallic au orefield that is currently being explored and constitutes the topic of this paper the beiya orefield is a composite mineral system with a distinct zoning surrounding the causative intrusions for instance the wandongshan the largest deposit in the beiya orefield exhibits a zoning with 1 porphyry au fe cu orebodies in the cupolas to the intrusions 2 au fe cu skarn orebodies along contact zones between the alkaline porphyritic intrusions and triassic limestone country rocks and 3 distal stratiform pb zn ag au epithermal orebodies subsequent au and cu bearing quartz ankerite veins and barren calcite veins overprint the earlier magmatic hydrothermal zoned ore system the hypogene orebodies were weathered to form supergene au ores at shallow levels which were historically termed laterite gold deposits the 2000 km nwn striking jinshajiang ailaoshan metallogenic province located in the three river region of western yunnan western sichuan and eastern tibet hosts numerous world class porphyry and skarn cu mo au ores associated with alkaline porphyry emplacement the beiya polymetallic au orefield a representative example of these ore types is located close to the triassic ailaoshan songma suture to the east and formed during eocene oligocene intraplate extension the distal stratiform pb zn ag au orebodies are hosted by bedding or detachment faults based on exploration data and previous research and combined with our detailed field investigation and further studies in the beiya area we propose a new and comprehensive porphyry skarn epithermal deposit model the model explains the geological setting ore characteristics metallogenic zoning and ore forming processes of the deposits in the beiya area it provides useful insights for further mineral exploration in the jinshajiang ailaoshan province for porphyry and skarn cu mo au ore systems associated with alkaline magmatism and may also be applied to other metallogenic provinces within similar continental arc settings

digital landform reconstruction using old and recent open access digital aerial photos abstract technological progress in remote sensing has enabled digital representation of terrain through new techniques e g digital photogrammetry and instruments e g 3d laser scanners however the use of old aerial images remains important in geosciences to reconstruct past landforms and detect long term topographic changes administrations have recently expressed growing interest in sharing photogrammetric datasets on public repositories providing opportunities to exploit these resources and detect natural and anthropogenic topographic changes the sfm mvs photogrammetric technique was applied to scanned historical black and white aerial photos of the serra de fontcalent alicante spain as well as to recent high quality digital aerial photos ground control points gcps extracted from a lidar derived three dimensional point cloud were used to georeference the results with non linear deformations two point clouds obtained with sfm mvs were compared with the lidar derived reference point cloud based on the result the quality of the models was analysed through the comparison of the stages on stable areas i e lands where no variations were detected and active areas with quarries new infrastructures fillings excavations or new buildings this study also indicates that errors are higher for old aerial photos up to 5 m on average than recent digital photos up to 0 5 m the application of sfm mvs to open access data generated 3d models that enhance the geomorphological analysis compared to stereophotogrammetry and effectively detected activities in quarries and building of landfills

an evaluation of the effectiveness of low cost uavs and structure from motion for geomorphic change detection abstract the measurement of topography and of topographic change is essential for the study of many geomorphic processes in recent years structure from motion sfm techniques applied to photographs taken by camera equipped unmanned aerial vehicles uavs has become a powerful new tool for the generation of high resolution topography the variety of available uav systems continues to increase rapidly but it is not clear whether increased uav sophistication translates into improved quality of the calculated topography to evaluate the lower end of the uav spectrum a simple low cost uav was deployed to calculate high resolution topography in the daan river gorge in western taiwan a site with a complicated 3d morphology and a wide range of surface types making it a challenging site for topographic measurement terrestrial lidar surveys were conducted in parallel with uav surveys in both june and november 2014 enabling an assessment of the reliability of the uav survey to detect geomorphic changes in the range of 30 cm to several meters a further uav survey was conducted in june 2015 in order to quantify changes resulting from the 2015 spring monsoon to evaluate the accuracy of the uav derived topography it was compared to terrestrial lidar data collected during the same survey period using the cloud to cloud comparison algorithm m3c2 the uav generated point clouds match the lidar point clouds well with rms errors of 30 40 cm however the accuracy of the sfm point clouds depends strongly on the characteristics of the surface being considered with vegetation water and small scale texture causing inaccuracies the lidar and sfm data yield similar maps of change from june to november 2014 with the same areas of geomorphic change detected by both methods the sfm generated change map for november 2014 to june 2015 indicates that the 2015 spring monsoon caused erosion throughout the gorge and highlights the importance of event driven erosion in the daan river the results suggest that even very basic uavs can yield data suitable for measuring geomorphic change on the scale of a channel reach

porphyry cu au and associated polymetallic fe cu au deposits in the beiya area western yunnan province south china abstract the alkaline porphyries in the beiya area are located east of the jinshajiang suture as part of a cenozoic alkali rich porphyry belt in western yunnan the main rock types include quartz albite porphyry quartz k feldspar porphyry and biotite k feldspar porphyry these porphyries are characterised by high alkalinity k2o na2o 10 high silica sio2 65 high sr 400 ppm and 87sr 86sr 0 706 ratio and were intruded at 65 5 ma between 25 5 to 32 5 ma and about 3 8 ma respectively there are five main types of mineral deposits in the beiya area 1 porphyry cu au deposits 2 magmatic fe au deposits 3 sedimentary polymetallic deposits 4 polymetallic skarn deposits and 5 palaeoplacers associated with karsts the porphyry cu au and polymetallic skarn deposits are associated with quartz albite porphyry bodies the fe au and polymetallic sedimentary deposits are part of an ore forming system that produced considerable au in the beiya area and are characterised by low concentrations of la ti and co and high concentrations of y yb and sc the cenozoic porphyries in western yunnan display increased alkalinity away from the triassic jinshajiang suture distribution of both the porphyries and sedimentary deposits in the beiya area are interpreted to be related to partial melting in a disjointed region between upper mantle lithosphere of the yangtze plate and gondwana continent and lie within a shear zone between buried palaeo tethyan oceanic lithosphere and upper mantle lithosphere caused by the subduction and collision of india and asia

sedimentology of acid saline lakes in southern western australia newly described processes and products of an extreme environment naturally acid saline systems with ph values between 1 7 and 4 are common on the yilgarn craton of southern western australia a combination of physical and chemical processes here yield a previously undescribed type of modern sedimentary environment flooding evapoconcentration desiccation and eolian transport at the surface as well as influx of acid saline groundwaters strongly influence these lakes halite gypsum kaolinite and iron oxides precipitate from acid hypersaline lake waters shallow acid saline groundwaters affect the sediments of the lakes and associated mudflats sandflats channels and dunes by precipitating early diagenetic halite gypsum iron oxides clays jarosite and alunite these modern environments would likely yield a rock record composed mostly of bedded red siliciclastic and reworked gypsum sand alternating with less common beds of bottom growth gypsum and halite with alteration by early diagenetic features diagnostic of acid saline waters this documentation of sedimentary processes and products of modern acid saline environments is an addition to the comparative sedimentology knowledge base and an expansion of the traditional models for classifying brines implications include better interpretations of terrestrial redbeds and lithified martian strata improved acid remediation methods new models for the formation and occlusion of pores and the new setting for finding previously undescribed extremophiles

mars surface diversity as revealed by the omega mars express observations the observatoire pour la mineralogie l eau les glaces et l activite omega investigation on board the european space agency mars express mission is mapping the surface composition of mars at a 0 3 to 5 kilometer resolution by means of visible near infrared hyperspectral reflectance imagery the data acquired during the first 9 months of the mission already reveal a diverse and complex surface mineralogy offering key insights into the evolution of mars omega has identified and mapped mafic iron bearing silicates of both the northern and southern crust localized concentrations of hydrated phyllosilicates and sulfates but no carbonates and ices and frosts with a water ice composition of the north polar perennial cap as for the south cap covered by a thin carbon dioxide ice veneer

a study of japanese landscapes using structure from motion derived dsms and dems based on historical aerial photographs new opportunities for vegetation monitoring and diachronic geomorphology abstract sfm mvs structure from motion and multiple view stereophotogrammetry is part of a series of technological progresses brought to the field of earth sciences during the last decade or so which has allowed geoscientists to collect unprecedented precise and extensive dsms digital surface model for virtually no cost rivaling lidar light detection and ranging technology previous work on sfm mvs in geosciences has been solely exploring data acquired for the purpose of sfm mvs but no research has been done in the exploration of photographic archives for geomorphological purposes therefore the present publications aims to present the usage of sfm mvs applied to historical aerial photographs in japan in order to 1 demonstrate the potentials to extract topographical and vegetation data and 2 to present the potential for chronological analysis of landscape evolution sfm mvs was implemented on black and white and colour aerial photographs of 1966 1976 1996 2006 and 2013 using the commercial software photoscanpro firstly the photographs were masked tied to gps points secondly the positions of the cameras and the 3d pointcloud were calculated and thirdly the 3d surface was created data were then exported in the gis software arcgis for analysis results also proved satisfactory for the reconstruction of 3d past geomorphological landscapes in coastal areas riverine areas and in hilly and volcanic areas they also prove that the height of trees and large vegetation features can also be calculated from aerial photographs alone diachronic analysis of the evolution in 3d landforms presented more difficulties because the resolution of the early photographs was lower than the recent ones volume and surface calculations should therefore be conducted carefully although the method holds merit and great promise in the exploration of active landscapes that have widely changed during the 20th century the authors have also reflected on the issues linked to large datasets mostly because the processing of these large datasets is still in need of improvement moreover there is no proof that an ever increasing resolution brings any major advance to the geomorphological paradigms

formation of anhydrous and hydrous skarn in cu au ore deposits by magmatic fluids most skarn ore deposits are characterized by two distinctly different alteration styles an early prograde stage with anhydrous minerals such as garnet and pyroxene forms from relatively high temperature hypersaline liquid a later retrograde stage with hydrous minerals such as epidote amphibole and chlorite plus sulfide ore minerals forms from lower temperature lower salinity fluids these two alteration stages commonly have been thought to reflect a dominance of magmatic and meteoric water respectively with relevance to the source of ore metals we report data from two different skarn systems one being part of the world s largest cu au resource stable isotope compositions of anhydrous and hydrous alteration minerals from both deposits indicate a magmatic source for both the prograde and retrograde stages 18o averages 5 0 per mil for garnet range 3 4 7 2 6 5 per mil for pyroxene 4 3 8 2 and 7 1 per mil for amphibole 4 3 8 7 the d values of late amphibole are more complex with magmatic values 77 to 78 for one deposit and both magmatic and lighter values for another deposit that could be explained either by magmatic degassing or by limited mixing with meteoric water we conclude that the differences in fluid composition prograde versus retrograde stages resulted from a magmatic fluid that intersected its solvus during the early stage creating vapor and hypersaline liquid whereas in the later stage this magmatic fluid did not intersect its solvus because it followed a different cooling path this late low salinity liquid only boiled once its vapor pressure curve was reached causing sulfide ore to precipitate during the retrograde stage

uav based remote sensing of the super sauze landslide evaluation and results unmanned aerial vehicles uavs equipped with digital compact cameras can be used to map landslides quickly and at a high ground resolution images taken by a radio controlled mini quad rotor uav of the super sauze france landslide have been used to produce a high resolution ortho mosaic of the entire landslide and digital terrain models dtms of several regions the uav capability for imaging fissures and displacements on the landslide surface has been evaluated and the subsequent image processing approaches for suitably georectifying the data have been assessed for super sauze horizontal displacements of 7 to 55 m between a high resolution airborne ortho photo of may 2007 and a uav based ortho mosaic of october 2008 have been measured fixed areas of persistent deformation have been identified producing fissures of different distributions and orientations comparable to glacial crevasses and relating directly to the bedrock topography the uav has demonstrated its capability for producing valuable landslide data but improvements are required to reduce data processing time for the efficient generation of ortho mosaics based on photogrammetric dtms in order to minimise georeferencing errors

weathering of olivine under co2 atmosphere a martian perspective abstract recent analyses from the curiosity rover at yellowknife bay gale crater mars show sedimentary rocks deposited in a lacustrine environment and containing smectite clays thought to derive from the alteration of olivine however little is known about the weathering processes of olivine under early martian conditions and about the stability of smectite clays in particular here we present a 3 month experiment investigating the weathering of forsteritic olivine powders fo 90 under a dense co 2 atmosphere and under present day terrestrial conditions for comparison the experiment also evaluates the potential effects of hydrogen peroxide h 2 o 2 as a representation of the highly oxidizing compounds produced by photochemical reactions throughout martian history the weathered samples were characterized by means of near infrared spectroscopy nir x ray diffraction xrd transmission electron microscopy with energy dispersive x ray spectrometry tem edx mossbauer spectroscopy and thermogravimetry the results show that a mg rich smectite phase formed from the weathering of olivine under co 2 conditions although in lower abundance than under terrestrial conditions the main secondary phase formed under co 2 turns out to be a silica rich phase possibly acting as a passivating layer with a non diagnostic near infrared spectral signature the use of h 2 o 2 highlights the critical importance of both the redox conditions and fe content of the initial olivine on the nature of the secondary phases

trace element geochemistry of magnetite and its relationship to cu bi co au ag u w mineralization in the great bear magmatic zone nwt canada the paleoproterozoic great bear magmatic zone is the focus of ongoing exploration for iron oxide copper gold iocg deposits and also hosts iron oxide apatite occurrences examples of iocg deposits in the great bear magmatic zone include sue dianne and nico and other smaller prospects including damp fab and nori ra the past producing terra mine property hosts significant iocg like alteration that contains dome shaped iron oxide apatite bodies petrographic study has identified multiple generations of magnetite at nico fab and nori ra and for the most part a single generation of magnetite at sue dianne damp and terra laser ablation inductively coupled plasma mass spectrometry la icp ms documents important geochemical differences in v ni cr and co concentrations within the magnetite variations of trace elements in magnetite from the great bear magmatic zone could be a result of 1 host rock fluid equilibration during regional metamorphism 2 postmetamorphic hydrothermal metasomatism of treasure lake group metasedimentary rocks 3 preferential solubility of co over ni within the fe rich fluids 4 changes in oxygen fugacity f o2 and 5 partitioning of elements into coprecipitating sulfides regionally the cr co ratio is higher in barren and pre ore magnetite compared to magnetite coprecipitated with ore minerals and or present in ore rich veins and breccias locally at the nori ra prospect the v ni ratio in magnetite differentiates between barren and ore related magnetite and at damp and sue dianne the co ni ratio is extremely high and clearly different from that of other great bear magmatic zone magnetite samples these results provide the first database for geochemically characterized magnetite from different stages of iocg alteration and illustrate the potential use of magnetite as an indicator mineral in the exploration for iocg deposits

melt recharge f o2 t conditions and metal fertility of felsic magmas zircon trace element chemistry of cu au porphyries in the sanjiang orogenic belt southwest china the magmatic hydrothermal pulang cu deposit triassic and the beiya au cu deposits eocene are located in the sanjiang copper porphyry belt southwest china zircon chemistry was used to constrain the magmatic evolution and oxidation state of the porphyries the results show that porphyries of the beiya district formed from an early oxidized melt and a later relatively reduced and more evolved magma whereas pulang experienced a normal cu porphyry evolutionary trend the pulang porphyries crystallized from more oxidized magma fmq 2 9 4 6 average 4 0 1 0 n 3 with an average temperature of 709 6 c compared to the beiya porphyries fmq 0 6 3 5 average 1 9 1 3 n 5 with a mean magmatic temperature of 780 22 c these data combined with data from other cu and au rich porphyries in the sanjiang belt i e machangjing cu yao an au are consistent with previous experimental work showing that elevated cu and au solubilities in magma require oxidizing conditions a compilation of existing geochemical data for magmatic zircons from fertile and barren porphyry systems worldwide establishes an optimal diagnostic interval on ceiv ceiii tti in zircon and eu eu n plots for generating magmatic hydrothermal cu au deposits

kinematics of a deep seated landslide derived from photogrammetric gps and geophysical data the deep seated landslide located at the intersection of the gradenbach and moll valleys near dollach austria has been the target of many previous investigations kronfellner kraus g 1980 neue untersuchungsergebnisse in wildbachen der talzuschub in abhangigkeit von niederschlagen int symp interpraevent bad ischl 1 179 192 weidner s moser m lang e 1998 influence of hydrology on sagging of mountain slopes talzuschube new results of time series analysis 8th international iaeg congress vancouver canada balkema rotterdam 1259 1266 weidner s 2000 kinematik und mechanismus tiefgreifender alpiner hangdeformationen unter besonderer berucksichtigung der hydrologischen verhaltnisse dissertation friedrich alexander universitat erlangen nurnberg 246 in this paper photogrammetric gps and geophysical data have been utilized to derive a constraint on the kinematics of the sagging process the photogrammetric models have been based on aerial photographs from 1962 and 1996 displacement vectors of about 50 individual characteristic points have been determined these clearly show the area of the sagging slope from 1999 to 2004 eleven gps campaigns have been carried out yielding very accurate displacement vectors at four monitoring points information about the internal structure of the slope was determined using seismic surveys the displacements observed by photogrammetry and gps have shown a rather uniform movement of the whole sagging slope with a slight longitudinal compression of 0 6 in order to extend the kinematic consideration to 3d a special form of the equation of continuity conservation of mass has been applied to the 1962 1996 photogrammetric data together with the cross sections derived from the seismic data the average velocities through cross sections have been calculated by integrals of the mass balance above and below these cross sections changes of the total rock mass due to accumulation and especially to erosion as well as an overall compaction of 1 5 between 1962 and 1996 have been considered the calculated average velocities through a cross section and the surface velocities independently determined by photogrammetry agree within an uncertainty of 15 the results indicate a block movement with shear concentration at the basal sliding surface

candidate subglacial volcanoes in the south polar region of mars morphology morphometry and eruption conditions 1 a number of isolated mountains mapped in the south polar region of mars are documented using mars global surveyor mgs mars orbiter laser altimeter mola and mars orbiter camera moc data these mountains have average separation distances of 175 km they are typically 30 40 km in diameter and 1000 1500 m high and their bases fall near an elevation of 1200 m a significant number of the population are located on or very close to a 660 km long line extending toward the south pole the summits of a number of these mountains have unusual shapes flat topped flat topped with a cone and large summit craters relative to the summit diameter sinuous channels are found in association with the margins of several of the mountains several modes of origin are considered for these mountains including impact tectonic and volcanic these mountains occur in intimate association with the hesperian aged dorsa argentea formation a unit containing features and structures interpreted to be related to a thick areally extensive ice sheet on the basis of these observations and analyses it is concluded that the most plausible origin for these mountains is volcanic and that they represent extrusion of lava from vents many of which lay underneath an ice sheet the unusual shape of many of the mountains is consistent with construction of a volcanic edifice underneath an ice sheet and melting of adjacent ice rich material sometimes forming drainage channels the topography of these mountains suggests that the ice sheet averaged at least 1 4 km thick at the time of eruption these features appear to be associated with early hesperian aged ridged plains hr

sulfur bearing phases detected by evolved gas analysis of the rocknest aeolian deposit gale crater mars the sample analysis at mars sam instrument suite detected so2 h2s ocs and cs2 from 450 to 800 c during evolved gas analysis ega of materials from the rocknest aeolian deposit in gale crater mars this was the first detection of evolved sulfur species from a martian surface sample during in situ ega so2 3 22 mol is consistent with the thermal decomposition of fe sulfates or ca sulfites or evolution desorption from sulfur bearing amorphous phases reactions between reduced sulfur phases such as sulfides and evolved o2 or h2o in the sam oven are another candidate so2 source h2s 41 109 nmol is consistent with interactions of h2o h2 and or hcl with reduced sulfur phases and or so2 in the sam oven ocs 1 5 nmol and cs2 0 2 1 nmol are likely derived from reactions between carbon bearing compounds and reduced sulfur sulfates and sulfites indicate some aqueous interactions although not necessarily at the rocknest site fe sulfates imply interaction with acid solutions whereas ca sulfites can form from acidic to near neutral solutions sulfides in the rocknest materials suggest input from materials originally deposited in a reducing environment or from detrital sulfides from an igneous source the presence of sulfides also suggests that the materials have not been extensively altered by oxidative aqueous weathering the possibility of both reduced and oxidized sulfur compounds in the deposit indicates a nonequilibrium assemblage understanding the sulfur mineralogy in rocknest materials which exhibit chemical similarities to basaltic fines analyzed elsewhere on mars can provide insight in to the origin and alteration history of martian surface materials

iron skarns of the vegas peladas district mendoza argentina the andean belt southwest of mendoza argentina hosts 23 fe fe cu and cu ag deposits classified variously in the literature as skarn iron oxide copper gold iocg and manto type cu deposits the vegas peladas deposit is one of the best exposed fe skarns with mineral assemblages and hydrothermal features similar to many other calcic fe skarns of the world the plutonic rocks of vegas peladas consist of a series of diorite to granite stocks dikes and sills the major trace and rare earth element geochemistry analyses of these igneous rocks indicate they were derived from subarc mantle sources the vegas peladas deposit formed by the overprinting of two different metamorphic and metasomatic events associated with early diorite and later granite intrusions alteration associated with the early diorite intrusion consists of a metamorphic halo 800 m wide and a zoned calcic skarn with inner garnet ad31 89 py0 2 clinopyroxene magnetite quartz intermediate garnet ad38 51 py1 2 clinopyroxene and distal veins of garnet ad92 100 clinopyroxene hd72 29 jo1 4 the latest alteration consists of widespread albite ab96 98 epidote quartz calcite chlorite pyrite titanite magnetite and hematite are the main iron ore minerals and occur as massive orebodies and veins associated with retrograde epidote and amphibole alteration of the diorite consists of early orthoclase quartz followed by later amphibole quartz magnetite epidote feldspar the granite related skarn overprints the earlier diorite related skarn and consists of garnet clinopyroxene scapolite me28 36 quartz alkali feldspar endoskarn and a zoned exoskarn with proximal garnet clinopyroxene quartz intermediate green garnet ad30 81 py0 1 clinopyroxene di82 93 jo4 2 and distal scapolite me25 36 ferroactinolite pyrite veins based on fluid inclusion stable isotope and ree data the prograde skarn formed at depths of 3 5 km under lithostatic pressure of 1 kbar from high temperature 670 400 c saline and iron rich 50 wt nacl equiv nacl kcl fecl2 magmatic fluids garnet 18oh2o 7 2 8 5 with intermediate oxygen fugacity iron ore and retrograde exoskarn assemblages formed under hydrostatic condition after the fracturing of early skarn fluids in this stage had lower temperature t 550 c and also generated saline 30 3 to 45 3 wt nacl equiv h2o nacl fecl2 vapor fluids by immiscibility that redistributed some of the iron from the previous skarn

diverse aqueous environments on ancient mars revealed in the southern highlands high resolution spectral images reveal many new exposures of hydrated minerals across the noachian southern highlands of mars several different phyllosilicates are observed with inferred accompanying phases ranging from zeolites to sulfates to chlorides each in distinct geologic settings hydrated sulfates are observed in several locations at mid latitudes and likely formed independently from the equatorial sulfates these assemblages suggest a greater diversity of aqueous environments on ancient mars than has previously been recognized and their distribution implies that alteration was widespread during the noachian period not restricted to a few locations

airborne laser scanning of forested landslides characterization terrain model quality and visualization abstract mapping complex landslides under forested terrain requires an appropriate quality of digital terrain models dtms which preserve small diagnostic features for landslide classification such as primary and secondary scarps cracks and displacement structures flow type and rigid type optical satellite imagery aerial photographs and synthetic aperture radar images are less effective to create reliable dtms under tree coverage here we utilized a very high density airborne laser scanning als data with a point density of 140 points m 2 for generating a high quality dtm for mapping landslides in forested terrain in the barcelonnette region the southern french alps we quantitatively evaluated the preservation of morphological features and qualitatively assessed the visualization of als derived dtms we presented a filter parameterization method suitable for landslide mapping and compared it with two default filters from the hierarchical robust interpolation hri and one default filter from the progressive tin densification ptd method the results indicate that the vertical accuracy of the dtm derived from the landslide filter is about 0 04 m less accurate than that from the ptd filter however the landslide filter yields a better quality of the image for the recognition of small diagnostic features as depicted by expert image interpreters several dtm visualization techniques were compared for visual interpretation the openness map visualized in a stereoscopic model reveals more morphologically relevant features for landslide mapping than the other filter products we also analyzed the minimal point density in als data for landslide mapping and found that a point density of more than 6 points m 2 is considered suitable for a detailed analysis of morphological features this study illustrates the suitability of high density als data with an appropriate parameterization for the bare earth extraction used for landslide identification and characterization in forested terrain

geochemistry of magnetite from proterozoic fe cu deposits in the kangdian metallogenic province sw china fe cu deposits in the kangdian fe cu metallogenic province sw china are hosted in paleoproterozoic meta volcanic sedimentary sequences and are spatially associated with coeval mafic intrusions several well known examples are the giant lala dahongshan and yinachang deposits they have a common paragenetic sequence of an early fe oxide stage associated with sodic alteration and a late cu sulfide stage associated with potassic carbonate alteration magnetite dominates the fe oxide stage of these deposits but is also present in the cu sulfide stage of the lala deposit this study uses trace element compositions of magnetite to examine the nature and origin of the ore forming fluids the magnetite has variable concentrations of ti al mg mn si v cr ca co ni sc zn cu mo sn and ga which are thought to have been controlled mainly by fluid compositions and or intensive parameters e g temperature and oxygen fugacity fo2 fluid rock interaction and coprecipitating mineral phases appear to be less important in controlling the magnetite compositions magnetite grains in the fe oxide stage of the lala and dahongshan deposits have comparable trace element compositions and were likely precipitated from chemically similar fluids high ni contents of magnetite in both deposits coupled with previous isotopic data and the fact that the two deposits are spatially associated with coeval mafic intrusions strongly suggest that the ore forming fluids were genetically related to the mafic magmas that formed the intrusions magnetite grains in the fe oxide stage of the yinachang deposit have much lower v and ni but higher sn and mo contents than those of the lala and dahongshan deposits and are thus thought to have precipitated from more oxidized and mo sn rich fluids that may have evolved from relatively felsic magmas magnetite grains from the cu sulfide and fe oxide stages of the lala deposit are broadly similar in composition but those in the cu sulfide stage have slightly higher cu zn and mn and are thought to have crystallized from relatively low temperature and cu zn mn rich fluids evolved from the fluids of the early fe oxide stage our results show that magnetite from the fe cu deposits in the kangdian province banded iron formation fe skarn deposits diabase hosted hydrothermal fe deposits and magmatic deposits has significantly different compositions we propose that covariations of co ni zn sn and co ni mn can be used to effectively discriminate different deposit types

structure from motion photogrammetry a low cost effective tool for geoscience applications abstract high resolution topographic surveying is traditionally associated with high capital and logistical costs so that data acquisition is often passed on to specialist third party organisations the high costs of data collection are for many applications in the earth sciences exacerbated by the remoteness and inaccessibility of many field sites rendering cheaper more portable surveying platforms i e terrestrial laser scanning or gps impractical this paper outlines a revolutionary low cost user friendly photogrammetric technique for obtaining high resolution datasets at a range of scales termed structure from motion sfm traditional softcopy photogrammetric methods require the 3 d location and pose of the camera s or the 3 d location of ground control points to be known to facilitate scene triangulation and reconstruction in contrast the sfm method solves the camera pose and scene geometry simultaneously and automatically using a highly redundant bundle adjustment based on matching features in multiple overlapping offset images a comprehensive introduction to the technique is presented followed by an outline of the methods used to create high resolution digital elevation models dems from extensive photosets obtained using a consumer grade digital camera as an initial appraisal of the technique an sfm derived dem is compared directly with a similar model obtained using terrestrial laser scanning this intercomparison reveals that decimetre scale vertical accuracy can be achieved using sfm even for sites with complex topography and a range of land covers example applications of sfm are presented for three contrasting landforms across a range of scales including an exposed rocky coastal cliff a breached moraine dam complex and a glacially sculpted bedrock ridge the sfm technique represents a major advancement in the field of photogrammetry for geoscience applications our results and experiences indicate sfm is an inexpensive effective and flexible approach to capturing complex topography

trace element geochemistry of magnetite from the giant beiya gold polymetallic deposit in yunnan province southwest china and its implications for the ore forming processes abstract the beiya gold polymetallic deposit is one of the largest gold deposits in china and is considered to be a typical porphyry skarn system located in the middle of the jinshajiang ailaoshan alkaline porphyry metallogenic belt massive magnetite is widespread in the beiya ore district but its genesis is still the subject of debate five representative magnetite types are present in the beiya deposit namely magmatic magnetite m1 from the ore related porphyry disseminated magnetite m2 from the early retrograde alteration massive magnetite m3 from the early quartz magnetite stage massive magnetite m4 from the middle quartz magnetite stage and magnetite m5 from the late quartz magnetite stage compared with the m1 magnetite the magnetites from stages m2 to m5 are depleted in ti al and high field strength elements implying a hydrothermal origin distinct from the magmatic accessory magnetite in the ore related porphyry m1 the concentrations of cobalt in the hydrothermal magnetites decrease gradually from m2 to m5 and can be used to discriminate the magnetite types the al mn and ti v contents of the successively precipitated magnetite grains m2 m5 suggests that the ore forming temperature decreased from m2 to m4 but increased from m4 to m5 possibly as the result of a new pulse of magma entering the chamber which may have triggered the gold mineralization the v content in the hydrothermal magnetite suggests that the oxygen fugacity increased from m2 to m4 but decreased as soon as the sulfides entered the system m5

variation in trace element content of magnetite crystallized from a fractionating sulfide liquid sudbury canada implications for provenance discrimination abstract laser ablation icp ms analysis has been applied to many accessory minerals in order to understand better the process by which the rock formed and for provenance discrimination we have determined trace element concentrations of fe oxides in massive sulfides that form ni cu pge deposits at the base of the sudbury igneous complex in canada the samples represent the crystallization products of fractionating sulfide liquids and consist of early forming fe rich monosulfide solution mss cumulates and residual cu rich intermediate solid solution iss this study shows that fe oxide geochemistry is a sensitive petrogenetic indicator for the degree of fractionation of the sulfide liquid and provides an insight into the partitioning of elements between sulfide and fe oxide phases in addition it is useful in determining the provenance of detrital fe oxide in a sulfide melt all lithophile elements cr ti v al mn sc nb ga ge ta hf w and zr are compatible into fe oxide the concentrations of these elements are highest in the early forming fe oxide titanomagnetite which crystallized with fe rich mss upon the continual crystallization of fe oxide from the sulfide liquid the lithophile elements gradually decrease so that late forming fe oxide magnetite which crystallized from the residual cu rich liquid is depleted in these elements this behavior is in contrast with fe oxides that crystallized from a fractionating silicate melt whereby the concentration of incompatible elements such as ti increases rather than decreases the behavior of the chalcophile elements in magnetite is largely controlled by the crystallization of the sulfide minerals with only ni co zn mo sn and pb present above detection limit in magnetite nickel mo and co are compatible in fe rich mss and thus the co crystallizing fe oxide is depleted in these elements in contrast magnetite that crystallized later from the fractionated liquid with cu rich iss is enriched in ni mo and co because fe rich mss is absent the concentrations of sn and pb which are incompatible with fe rich mss are highest in magnetite that formed from the fractionated cu rich liquid at subsolidus temperatures ilmenite exsolved from titanomagnetite whereas al spinel exsolved from the cores of some magnetite locally redistributing the trace elements however during laser ablation icp ms analysis of these fe oxides both the magnetite and its exsolution products are ablated so that the analysis represents the original magmatic composition of the fe oxide that crystallized from the sulfide melt

distribution of porphyry deposits in the eurasian continent and their corresponding tectonic settings in the eurasian continent there are three huge metallogenic belts of cu and mo porphyry deposits comprising the paleozoic central asian ore belt in the north the tethyan eurasian ore belt of jurassic to cenozoic age in the southwest and the east margin ore belt of the eurasian continent of jurassic to cretaceous age in the east the latter is considered to be part of the vast circum pacific ore belt some of the main features of the spatial temporal distribution of cu and mo porphyry systems and related geodynamic processes of the three metallogenic belts are described in particular the key role of postsubduction related porphyry ore systems is emphasized comprising collisional and post collisional cu mo porphyry deposits during the geological history of the eurasian continent the recurrent feature of these ore systems and related felsic rocks is their derivation from partial melting of stagnant or residual oceanic slabs and mixing with a variable amount of crustal material during magma ascent to shallower levels 2013 published by elsevier ltd

in situ la icp ms u pb geochronology and trace elements analysis of polygenetic titanite from the giant beiya gold polymetallic deposit in yunnan province southwest china abstract the beiya gold polymetallic deposit located in the middle of the jinshajiang ailaoshan alkaline porphyry metallogenic belt is one of the largest gold deposits in china the mineralization mainly occurs in skarn along the intrusive contacts between the alkaline porphyries and middle triassic limestone in this paper we present u pb age as well as major and trace element geochemistry of titanite from the beiya deposit and distinguish the titanite into a magmatic and a hydrothermal suite our study indicates that the titanite from the ore related porphyry and from the mineralized skarn is texturally and geochemically very different the euhedral envelope shaped titanite from the ore related porphyry has lower feo f hfses nb ta and lu hf together with higher tio2 and th u than the subhedral titanite from the mineralized skarn the titanite from the porphyry also displays higher lree hree and more subtle negative eu anomaly than its mineralized skarn counterpart this suggests a magmatic and a hydrothermal origin for respectively the titanite from the ore related porphyry and from the mineralized skarn in situ magmatic titanite u pb dating has yielded an eocene age of 36 0 5 9 ma consistent with the porphyry zircon u pb age 36 07 0 43 ma obtained in previous studies hydrothermal titanite has yielded a weighted average 206pb 238u age of 33 1 1 0 ma mswd 2 0 which represents the age of the retrograde skarn alteration and the maximum age for the gold mineralization together with the previous molybdenite re os age we have further constrained the beiya gold polymetallic metallogeny to 33 1 34 1 ma the mineralization age is slightly younger than the porphyry emplacement indicating that the beiya metallogeny was likely to be a post magmatic hydrothermal product of the himalayan orogenic event the ree characteristics of hydrothermal titanite also reveal that the ore forming fluids may have been derived from a highly oxidized magma

hirise imaging of impact megabreccia and sub meter aqueous strata in holden crater mars high resolution imaging science experiment hirise images of holden crater mars resolve impact megabreccia unconformably overlain by sediments deposited during two noachian age phases of aqueous activity a lighter toned lower unit exhibiting phyllosilicates was deposited in a long lived quiescent distal alluvial or lacustrine setting an overlying darker toned and often blocky upper unit drapes the sequence and was emplaced during later high magnitude flooding as an impounded uzboi vallis lake overtopped the crater rim the stratigraphy provides the first geologic context for phyllosilicate deposition during persistent wet and perhaps habitable conditions on early mars

la icp ms trace element analysis of magnetite and pyrite from the hetaoping fe zn pb skarn deposit in baoshan block sw china implications for ore forming processes abstract the hetaoping deposit is one of the largest fe zn pb skarn deposit in sw china which is characterized by zn pb mineralization in the upper part and the fe mineralization in the deeper part the fe mineralization is dominated by magnetite and pyrite magnetite can be subdivided into four types primary banded magnetite samples in clinopyroxene actinolite skarn mt 1 primary disseminated magnetite in garnet skarn mt 2 primary disseminated magnetite in clinopyroxene actinolite skarn mt 3 and altered magnetite in clinopyroxene actinolite skarn mt 4 pyrite can be subdivided into three types pyrite in oxide ore stage py 1 pyrite in early sulfide ore stage py 2 and pyrite in late sulfide ore stage py 3 the flat time resolved signals of laser ablation inductively coupled plasma mass spectrometry la icp ms imply that trace elements exist mainly in the form of isomorphism in magnetite and pyrite with the exception some incompatible trace elements e g ca k and na in magnetite and pb bi and ag in pyrite trace element concentrations in magnetite and pyrite demonstrate that the ore forming fluid in hetaoping is of magmatic origin furthermore compared to porphyry iocg kinuna and bif type magnetite the magnetite from hetaoping has relatively low ti v and ni concentrations but high al mn and ca concentrations implying a typical skarn genesis the variation of ti concentrations in magnetite is an indication of the formation temperature and shows that banded magnetite mt 1 precipitated in a relatively high temperature environment compared with disseminated magnetite mt 2 and mt 3 compared to mt 1 and mt 3 mt 2 has a higher si al and w contents and a lower mg and mn contents the mn content increases from py 1 to py 2 and decreases from py 2 to py 3 suggesting that the fluid rock interaction increased from the oxide ore stage to the sulfide ore stage and decreased from sulfide ore stage to post ore stage the variation of the v concentration in magnetite grains indicates a relatively higher oxygen fugacity of mt 2 compared to mt 1 and mt 3 implying that the oxygen fugacity of the ore forming fluid in the garnet skarn zone is higher than that in clinopyroxene actinolite skarn zone the variable oxygen fugacity probably caused spatial zoning of mineralization in hetaoping fe zn pb skarn deposit the temperature and oxygen fugacity of the ore forming fluid and the extent of fluid rock interaction controlled the temporal order and spatial zonation of magnetite and sulfide precipitation which led to the formation of the hetaoping fe zn pb skarn deposit

in situ la icp ms trace elemental analyses of magnetite the late palaeoproterozoic sokoman iron formation in the labrador trough canada abstract the sokoman iron formation in the labrador trough canada a typical granular iron formation gif is coeval with the 1 88 ga nimish volcanic suites in the same region it is composed of the lower middle and upper iron formations in addition to primary and altered magnetite in iron formations of the hayot lake rainy lake and wishart lake areas magnetite in volcanic breccia associated with the iron formation is identified for the first time in the stratigraphy trace elemental compositions of the most primary altered and volcanic brecciated magnetite of the sokoman iron formation were obtained by la icp ms commonly detected trace elements of magnetite include ti al mg mn v cr co and zn these three types of magnetite have different trace elemental compositions primary magnetite in the iron formation has a relatively narrow range of compositions with the depletion of ti pb mg and al magnetite from volcanic breccia is rich in ti al v mn mg zn cu and pb indicative of crystallization from mantle derived magmas altered magnetite in the iron formation shows a relatively wide range of trace elemental compositions mineralizing fluids associated with magmas that generated the 1 88 ga nimish volcanic suites circulated through the sedimentary piles to further enrich the iron formations and to form magnetite with variable compositions the comparisons of different types of primary and altered magnetite in the iron formation in the region show distinct provenance discrimination our findings also support the origin of iron formations in association with multiple stages of exhalative volcanic and hydrothermal processes

reequilibration processes in magnetite from iron skarn deposits textural and compositional data for magnetite from nine iron skarn deposits in canada romania and china show that most samples have reequilibrated by dissolution and reprecipitation oxy exsolution and or recrystallization the dissolution and reprecipitation processes are most extensive and are present in most magnetite samples examined whereas the oxy exsolution occurs only in high ti magnetite forming exsolution lamellae of fe ti al oxides electron microprobe analysis indicates that the reequilibration processes have significantly modified the minor and trace element compositions of magnetite notably si mg ca al mn and ti whereas oxy exsolution is effective in decreasing the ti content of high ti magnetite many analyses of magnetite grains from the skarn deposits plot variably in the banded iron formations bif iron oxide copper gold iocg or porphyry cu fields using the ti v versus ca al mn discrimination diagram this pattern suggests that trace element data for magnetite that has unusual composition and or reequilibrated cannot be reliably used as a petrogenetic indicator mixing of externally derived saline fluids with fe rich magmatic hydrothermal solutions an increase in temperature and local decreasing pressure and f o 2 are considered the most important causes for the dissolution and reprecipitation or recrystallization of the magnetite increasing f o 2 and decreasing temperature may facilitate oxy exsolution of fe ti al oxides in high ti magnetite results presented here highlight the importance of detailed textural characterization prior to in situ chemical analysis of magnetite grains so that mineral compositions can be properly evaluated in terms of the genesis and evolution of iron skarn deposits

straightforward reconstruction of 3d surfaces and topography with a camera accuracy and geoscience application topographic measurements for detailed studies of processes such as erosion or mass movement are usually acquired by expensive laser scanners or rigorous photogrammetry here we test and use an alternative technique based on freely available computer vision software which allows general geoscientists to easily create accurate 3d models from field photographs taken with a consumer grade camera the approach integrates structure from motion sfm and multi view stereo mvs algorithms and in contrast to traditional photogrammetry techniques it requires little expertise and few control measurements and processing is automated to assess the precision of the results we compare sfm mvs models spanning spatial scales of centimeters a hand sample to kilometers the summit craters of piton de la fournaise volcano with data acquired from laser scanning and formal close range photogrammetry the relative precision ratio achieved by sfm mvs measurement precision observation distance is limited by the straightforward camera calibration model used in the software but generally exceeds 1 1000 i e centimeter level precision over measurement distances of 10s of meters we apply sfm mvs at an intermediate scale to determine erosion rates along a 50 m long coastal cliff seven surveys carried out over a year indicate an average retreat rate of 0 70 0 05 m a 1 sequential erosion maps at 0 05 m grid resolution highlight the spatio temporal variability in the retreat with semivariogram analysis indicating a correlation between volume loss and length scale compared with a laser scanner survey of the same site sfm mvs produced comparable data and reduced data collection time by 80

laboratory simulations of acid sulfate weathering under volcanic hydrothermal conditions implications for early mars we have completed laboratory experiments and thermochemical equilibrium models to investigate secondary mineral formation under conditions akin to volcanic hydrothermal acid sulfate weathering systems our research used the basaltic mineralogy at cerro negro volcano nicaragua characterized by plagioclase pyroxene olivine and volcanic glass these individual minerals and whole rock field samples were reacted in the laboratory with 1 molal sulfuric acid at varying temperatures 65 150 and 200 c fluid rock weight ratios 1 1 4 1 and 10 1 and durations 1 60 days thermochemical equilibrium models were developed using geochemist s workbench to understand the reaction products and fluids we employed scanning electron microscopy energy dispersive spectroscopy x ray diffraction and inductively coupled plasma atomic emission spectroscopy the results of our experiments and models yielded major alteration minerals that include anhydrite natroalunite minor iron oxide and amorphous al si gel we found that variations in experimental parameters did not drastically change the suite of minerals produced instead abundance size and crystallographic shape changed our results also suggest that it is essential to separate phases formed during experiments from those formed during fluid evaporation to fully understand the reaction processes our laboratory reacted and model predicted products are consistent with the mineralogy observed at places on mars however our results indicate that determination of the formation conditions requires microscopic imagery and regional context as well as a thorough understanding of contributions from both experiment precipitation and fluid evaporation minerals

compositional stratigraphy of clay bearing layered deposits at mawrth vallis mars phyllosilicates have previously been detected in layered outcrops in and around the martian outflow channel mawrth vallis crism spectra of these outcrops exhibit features diagnostic of kaolinite montmorillonite and fe mg rich smectites along with crystalline ferric oxide minerals such as hematite these minerals occur in distinct stratigraphic horizons implying changing environmental conditions and or a variable sediment source for these layered deposits similar stratigraphic sequences occur on both sides of the outflow channel and on its floor with al clay bearing layers typically overlying fe mg clay bearing layers this pattern combined with layer geometries measured using topographic data from hirise and hrsc suggests that the al clay bearing horizons at mawrth vallis postdate the outflow channel and may represent a later sedimentary or altered pyroclastic deposit that drapes the topography

the polygonal surface structures in the dalangtan playa qaidam basin nw china controlling factors for their formation and implications for analogous martian landforms