geochemistry and fluid characteristics of the dalli porphyry cu au deposit central iran abstract the miocene dalli porphyry cu au deposit in the central part of urumieh dokhtar magmatic arc is the first reported au rich porphyry cu deposit in the zagros orogenic belt the cu au mineralization is mainly hosted in diorite and quartz diorite intrusions presenting as numerous veinlets in the altered wall rocks with potassic phyllic and propylitic alteration developed based on the mineral assemblages and crosscutting relations of veinlets hydrothermal mineralization alteration occurred in at least three stages characterized by veinlets of 1 qtz kfs mag ccp 2 qtz py ccp bn cv cc and 3 qtz chl bt the ore bearing intrusions exhibit typical geochemical characteristics of subduction zone magmas including lree fractionated pattern strong enrichment in lile cs rb ba pb and u and depletion of hfse with marked negative ti and nb anomalies the adakite like ore hosting porphyry intrusions are characterized by a systematic gradual decreasing and increasing of y and eu eu with increasing sio2 content respectively moreover they exhibit a significant increasing trend of sr y with decreasing of y which indicates progressive hornblende fractionation and suppression of plagioclase fractionation during the evolution toward high water content of parental magma a relatively flat hree pattern with low dyn ybn and nb ta values may represent that amphibole played a more important role than garnet in the generation of the adakitic melts in the thickened lower crust based on the phase assemblages confirmed by detailed laser raman spectroscopy analyses and proportion of solid liquid and gaseous components five types of fluid inclusions were recognized which are categorized as 1 liquid rich two phase liquidh2o vaporh2o iia 2 vapor rich two phase vaporh2o co2 liquidh2o iib 3 high saline simple fluids iiia liquidh2o vaporh2o hl 4 high saline opaque mineral bearing fluids iiib liquidh2o vaporh2o hl hem ccp py and 5 multi phase type iiiab liquidh2o vaporh2o hl anh hem mag ccp in early stage veins the homogenization temperature of multiphase inclusions as high as 620 c with corresponding salinities of up to 75 wt nacl equivalent represent the initial ore forming fluids from early to late stage veins the gradual decrease of homogenization temperature of saline inclusions iiiab iiia and iiib from 620 to 340 c corresponding salinities of 75 35 wt nacl equivalent may reflect fluid boiling and mixing of the early magmatic fluids with circulating groundwater the common association of hematite and anhydrite daughter phases with the most primitive inclusions iiiab in early stage veins and the lack of co2 bearing inclusions in the middle to late stage veins reveal co2 content and oxygen fugacity of the fluids was significantly decreased from early to main stage of sulfide mineralization second generation of veins it seems that magnetite crystallization and co2 escape have a decisive role in oversaturation of s2 and subsequent rapid and large scale precipitation of sulfides in second generation of veins at the dalli deposit

genesis of the fuxing porphyry cu deposit in eastern tianshan china evidence from fluid inclusions and c h o s pb isotope systematics abstract the fuxing porphyry cu deposit is a recently discovered deposit in eastern tianshan xinjiang northwestern china the cu mineralization is associated with the fuxing plagiogranite porphyry and monzogranite mainly presenting as various types of hydrothermal veins or veinlets in alerted wall rocks with potassic chlorite phyllic and propylitic alteration developed the ore forming process can be divided into four stages stage i barren quartz veins stage ii quartz chalcopyrite pyrite veins stage iii quartz polymetallic sulfide veins and stage iv quartz calcite veins four types of fluid inclusions fis can be distinguished in the fuxing deposit including hypersline h type vapor rich two phase v type liquid rich two phase l type and trace amounts of pure vapor inclusions p type but only the stage i quartz contains all types of fis the stages ii and iii quartz have two types of fis with exception of h and p types in stage iv quartz minerals only the l type inclusions can be observed the fis in quartz of stages i ii iii and iv are mainly homogenized at temperatures of 357 518 c 255 393 c 234 322 c and 145 240 c with salinities of 1 9 11 6 wt nacl equiv 1 6 9 6 wt nacl equiv 1 4 7 7 wt nacl equiv and 0 9 3 7 wt nacl equiv respectively the ore forming fluids of the fuxing deposit are characterized by high temperature moderate salinity and relatively oxidized condition carbon hydrogen and oxygen isotopic compositions of quartz indicate that the ore forming fluids were gradually evolved from magmatic to meteoric in origin sulfur and lead isotopes suggest that the ore forming materials were derived from a deep seated magma source the cu mineralization in the fuxing deposit occurred at a depth of 1 km and the changes of oxygen fugacity decompression boiling and local mixing with meteoric water were most likely critical for the formation of the fuxing cu deposit

synthetic aperture radar observation of ocean roughness from rolls in an unstable marine boundary layer simultaneous synthetic aperture radar sar and cloud photographic observations of the atlantic ocean off the coast of florida were made from a high altitude aircraft when there was an unstable marine boundary layer the synthetic aperture radar images show unusual kilometer sized features on the ocean surface which are related to clouds the ocean near shore was cloud free and had no radar features while from 30 to 330 km offshore there were clouds and prominent kilometer sized features in the sar image these radar features are most prominent when the radar was looking upwind are less prominent when the radar was looking downwind and disappear entirely when the radar was looking crosswind since ocean radar echo strengths are believed to be controlled primarily by ocean waves satisfying the bragg relation these radar features most likely resulted from local enhancements of short gravity waves with 17 to 34 cm wavelengths which in turn are surface expressions of roll convections in a kilometer thick unstable marine boundary layer

genesis of the saishitang skarn type copper deposit west qinling qinghai province evidence from fluid inclusions and stable isotopes the saishitang skarn type copper deposit located in the southeast part of the dulan ela mountain triassic volcanic magmatic arc and forearc accretionary wedge belongs to the tongyugou saishitang tin copper polymetallic ore field in west qinling qinghai province based on the contact crosscutting relationships mineral associations and mineralization characteristics hydrothermal fluid evolution can be divided into three stages skarn i quartz sulfide ii and polymetallic sulfide bearing quartz calcite vein iii the quartz sulfide stage ii can be further divided into a massive sulfide stage ii 1 and a layered sulfide stage ii 2 this paper presents detailed analysis of fluid inclusions h o s and pb isotope compositions of rock samples from each of the above three stages as well as analysis of fluid inclusions from quartz diorite the homogenization temperature salinity density and pressure of fluid inclusions in quartz diorite and typical transparent minerals showed a tendency of gradual decline in these evolutionary stages the ore forming fluid can be classified as a na ca2 so42 cl system with a minor proportion of a na ca2 no3 so42 system which likely resulted from mixing of magmatic and formation water the h o isotope composition indicates that the proportion of formation water increased during the ore forming process and meteoric water was mixed in the late quartz calcite vein stage the 34s cdt values 6 45 5 57 and pb isotope compositions show that the ore forming materials were mainly derived from magmatic fluid ore forming fluid was boiling during the main ore forming stage ii 1 due to pressure decrease consequently the physical and chemical conditions i e ph eh fo2 fs2 changed and metallic elements including cu in the fluid could no longer exist in the form of complexes and precipitated from the fluid according to the integrated analysis of ore features mineral associations alteration characteristics ore forming environment and fluid evolutionary process it is concluded that the saishitang deposit is a typical skarn deposit

numerical study on signatures of atmospheric convective cells in radar images of the ocean current and wind variations at the ocean surface can give rise to a modulation of the sea surface roughness and thus become visible in radar images the discrimination between radar signatures of oceanic and atmospheric phenomena can be quite difficult since signatures of different origin can have very similar shapes and magnitudes and are often superimposed upon each other in this work we employ a numerical radar imaging model for an investigation of typical properties of radar signatures of atmospheric convective cells and of theoretical differences between such atmospherically induced radar signatures and those of oceanic phenomena we show that main characteristics of observed multifrequency multipolarization radar signatures of atmospheric convective cells over the gulf stream are reproduced quite well by the proposed model this encourages us to vary wind and radar parameters systematically in order to get a general overview of the dependency of atmospherically induced radar signatures on these parameters finally we compare typical characteristics of radar signatures of atmospheric and oceanic phenomena and we present simulated radar images of a scenario of superimposed atmospheric convective cells and oceanic internal waves we show that the proposed model supports the experimental finding that radar signatures of oceanic phenomena are stronger at horizontal hh than at vertical vv polarization while atmospherically induced radar signatures are better visible at vv polarization

geology geochronology fluid inclusion and h o isotope geochemistry of the luoboling porphyry cu mo deposit zijinshan orefield fujian province china abstract the luoboling cu mo deposit in the zijinshan orefield fujian province southeastern china is a large porphyry deposit hosted by the sifang granodiorite and the luoboling granodiorite porphyry the largest cu mo orebody is saddle shaped with various types of hydrothermal veinlets intensive hydrothermal alteration in the deposit is characterized by outward zoning from potassic overprinted by phyllic alteration to phyllic and alunite dickite alteration based on the mineral assemblages and crosscutting relationships of veins the ore forming process can be divided into three stages namely an early stage k feldspar quartz magnetite molybdenite veins associated with potassic alteration a middle stage quartz molybdenite chalcopyrite pyrite veins in phyllic zone and a late stage quartz gypsum veins in the phyllic and alunite dickite alteration zones six molybdenite separates yield a re os isochron age 104 6 1 0 ma which is identical to the age of emplacement of the sifang and luoboling granodiorite porphyries three types of fluid inclusions fis were observed at the luoboling deposit 1 nacl h 2 o aqueous 2 daughter mineral bearing and 3 co 2 h 2 o fluid inclusions fis of the early and middle stages are predominantly vapor rich aqueous and daughter mineral bearing inclusions together with minor co 2 rich and liquid rich aqueous inclusions whereas the late stage minerals only contain liquid rich aqueous inclusions homogenization temperatures and salinities of fis trapped in the early stage minerals range from 420 to 540 c and 0 4 to 62 9 wt nacl equiv respectively fis of the middle stage yield homogenization temperatures of 340 to 480 c and salinities of 0 5 to 56 0 wt nacl equiv co 2 content and the oxygen fugacity indicated by daughter minerals of fis trapped in middle stage minerals are lower than those in the early stage the liquid rich aqueous inclusions of the late stage homogenize at temperatures of 140 to 280 c yielding salinities of 0 4 to 8 4 wt nacl equiv the minimum estimated pressures of the three stages are 30 70 mpa 10 40 mpa and 1 10 mpa respectively corresponding to minimum ore forming depths of 1 2 8 km fluids trapped in early middle and late stages yield d values of 67 to 54 54 to 70 and 62 and 18 o values of 5 4 to 6 7 2 8 to 4 2 and 2 1 respectively fluid boiling which resulted in the formation of stockworks and the precipitation of sulfides occurred in the early and middle stages the fluids subsequently evolved into a low temperature low salinity system in the late stage along with an input of meteoric water the luoboling porphyry cu mo system was developed in a transition from continental arc to back arc extension region which was related to the westward subduction of the paleo pacific plate beneath the huanan orogen

a review of the western part of the altaids a key to understanding the architecture of accretionary orogens abstract the altaids is one of the largest accretionary collages in the world and the tectonic styles of the accretionary processes have been interpreted in several ways including as an amalgamation of multiple terranes as a result of oroclinal bending of a long single arc or as a caledonian continental collision based on recent tectonostratigraphic analyses together with paleomagnetic data the tectonic styles of the neoproterozoic to paleozoic accretionary processes of the altaids are discussed the western altaids is the main focus of the study which was mainly composed of several independent linear components such as arcs and microcontinents with proterozoic basement and cover rocks various kinds of arcs existed in the paleo asian ocean including a complicated type of arc alaskan type which is a combination of the japan and mariana type intra oceanic arcs and the cordillera type continental arcs these linear components rotated and collided with each other with multiple subduction polarities which could have been an important result of multiple linear element amalgamation and which has contributed greatly to the architecture of the eurasian continent the basic tectonic styles of the altaids can be summarized as arc arc collision oroclinal bending and large scale rotation and multiple subductions with a complicated archipelago paleogeography these basic features of accretionary orogens in general can be attributed to the amalgamation of complicated multiple linear elements some mesozoic to cenozoic accretionary orogens in the world are also characterized by processes of multiple linear element amalgamation more attention should be paid to the multiple linear element amalgamation of ancient accretionary orogens which will shed light on lateral and vertical continental growth

the adakite connection of the tuwu yandong copper porphyry belt eastern tianshan nw china trace element and sr nd pb isotope geochemistry the tuwu yandong porphyry copper belt lies in the eastern tianshan mountains eastern section of the central asian orogenic belt the copper mineralization is mainly hosted in plagiogranite porphyries intruded into early carboniferous volcanic rocks of the paleozoic dananhu island arc between the tarim and siberian plates the plagiogranite porphyries have contents of 65 73 wt sio2 14 17 wt al2o3 0 9 2 2 wt mgo 3 16 ppm y 0 4 1 40 ppm yb 347 920 ppm sr and positive eu anomalies the rocks also exhibit positive nd t values 5 0 to 9 4 and low initial 87sr 86sr values 0 70316 0 70378 such features are similar to those of adakites derived from partial melting of a subduction related oceanic slab the mineralization age is early carboniferous 350 320 ma which is close to that of the porphyries the close relationship between the cu mineralization and the porphyry is also indicated by their similar sr nd pb isotopic compositions we suggest that the copper porphyry magma system in the dananhu island arc was formed by direct melting of an obliquely subducting early carboniferous oceanic slab

ore genesis and hydrothermal evolution of the kendenggao er copper molybdenum deposit western tianshan evidence from isotopes s pb h o and fluid inclusions abstract the boluokenu range is one of the most important metallogenic belts in northwest china and it contains numerous fe cu mo au etc deposits the kendenggao er cu mo deposit is located in the eastern segment of the boluokenu metallogenic belt within the western tianshan orogeny skarn and cu mo orebodies occur as lamellae or lenses along the contacts between different units of the upper carboniferous dongtujinhe formation and the aimujin granitic intrusions based on field investigations and petrographic observations three main metallogenic stages of skarn formation and ore deposition have been distinguished 1 the pre ore stage is characterized by the formation of garnet wollastonite and diopside and high temperature hypersaline hydrothermal fluids with oxygen isotopic compositions that are similar to those of magmatic fluids these fluids were most likely generated by the separation of brine from the silicate melt due to the immiscibility of primary magmatic fluids that occurred at a depth of approximately 1 km with inferred lithostatic pressure conditions of 300 bars 2 the main ore stage coincides with the replacement of garnet and diopside by vesuvianite epidote sulfides and quartz the hydrothermal fluids of this stage are represented by v type vapor rich fluid inclusions that coexist with l type liquid rich inclusions the oxygen isotope 18oh2o values of the main ore stages are in a narrow range of 7 5 9 9 which indicates that the mineralization related fluid is also of magmatic origin based on the fluid inclusion and stable isotopic data it can be concluded that the ore forming fluid evolved by the boiling of the magmatic fluids that likely occurred at a depth of 1 km and hydrostatic pressure of 100 bars and that this was the predominant mechanism for the large scale precipitation in the kendenggao er cu mo deposit 3 the post ore stage is characterized by the development of calcite quartz and chlorite the fluids during this stage are represented by the l type inclusions which mainly show low salinity and low homogenization temperatures these fluids yield the lowest 18oh2o values 2 8 to 3 7 the above data indicate that the post ore stage fluids originated from the mixing of residual main ore stage fluids with various proportions of external water low salinity low temperature no boiling occurred at this stage at the low temperatures the 34s values of the sulfides range from 4 3 to 1 9 and the 206pb 204pb 207pb 204pb and 208pb 204pb values of the sulfides range from 18 220 to 18 554 15 608 to 15 812 and 38 080 to 39 055 respectively the s and pb isotopic compositions indicate that the ore materials were mainly derived from magmas taken together these geologic geochemical and isotopic data confirm that kendenggao er is a typical skarn deposit

ore forming process of the huijiabao gold district southwestern guizhou province china evidence from fluid inclusions and stable isotopes abstract the huijiabao gold district is one of the major producers for carlin type gold deposits in southwestern guizhou province china including taipingdong zimudang shuiyindong bojitian and other gold deposits occurrences petrographic observation microthermometric study and laser raman spectroscopy were carried out on the fluid inclusions within representative minerals in various mineralization stages from these four gold deposits five types of fluid inclusions have been recognized in hydrothermal minerals of different ore forming stages aqueous inclusions co2 inclusions co2 h2o inclusions hydrocarbon inclusions and hydrocarbon h2o inclusions the ore forming fluids are characterized by a h2o co2 ch4 n2 system with medium to low temperature and low salinity from early mineralization stage to later ones the compositions of the ore forming fluids experienced an evolution of h2o nacl h2o nacl co2 ch4 n2 h2o nacl ch4 co2 with a slight decrease in homogenization temperature and salinity the 18o values of the main stage quartz vary from 15 2 to 24 1 while the dh2o and calculated 18oh2o values of the ore forming fluids range from 56 9 to 116 3 and from 2 12 to 12 7 respectively the 13cpdb and 18osmow values of hydrothermal calcite change in the range of 9 1 to 0 5 and 11 1 23 2 respectively stable isotopic characteristics indicate that the ore forming fluid was mainly composed of ore and hydrocarbon bearing basinal fluid the dynamic fractionation of the sulfur in the diagenetic pyrite is controlled by bacterial reduction of marine sulfates the hydrothermal sulfides and the diagenetic pyrite from the host rocks are very similar in their sulfur isotopic composition suggesting that the sulfur in the ore forming fluids was mainly derived from dissolution of diagenetic pyrite the study of fluid inclusions indicates that immiscibility of h2o nacl co2 fluids took place during the main mineralization stage and caused the precipitation and enrichment of gold

the carbonate clastic cycles of the east alpine raibl group result of third order sea level fluctuations in the carnian abstract the carnian raibl group of the eastern alps consists of three 50 100 m thick alternating carbonate and clastic third order cycles each of which can be traced for hundreds of kilometers tectono eustatic sea level fluctuations of a few tens of metres spanning a few millions of years are the driving mechanism of this cyclicity the carbonate intervals represent restricted marginal marine tidal and evaporitic environments the clastic intervals represent inner and outer shelf facies and are related to the fluviatile schilfsandstein of the germanic facies belt in the raibl group contrary to other carbonate clastic depositional settings relative sea level lowstands are dominated by carbonate production and highstands are dominated by clastic deposition each of the three raibl cycles corresponds to a type 2 sequence containing shelf margin transgressive and highstand systems tracts during sea level lowstands deltaic point sources were near the shelf margin allowing clastics to bypass the carbonate platform this setting corresponds to a shelf margin systems tract transgressive and highstand systems tracts developed during the subsequent sea level rise as deltaic clastics were reworked and redistributed over the carbonate platform and the deltas retrograded to the inner shelf the highstand systems tracts are capped by a type 2 sequence boundary which is conformable in the study area the systems tracts can be further subdivided into shallowing upward subcycles caused by fourth order sea level fluctuations believed to represent milankovitch rhythms the middle raibl cycle is consistently thinner and may represent a shorter termed third order sea level fluctuation our data also corroborate a second order transgressive trend for the carnian

observation of a nonlinear wave disturbance in the marine atmosphere by the synthetic aperture radar aboard the ers 1 satellite a nonlinear wave disturbance in the marine atmosphere associated with an atmospheric cold front has been identified on a spaceborne radar image of the north sea by its imprint on the sea surface this nonlinear wave disturbance is either a solitary wave disturbance or an undular bore propagating in the lower marine atmosphere the radar image showing sea surface manifestations of this atmospheric wave disturbance was acquired over the north sea by the synthetic aperture radar sar aboard the first european remote sensing satellite ers 1 on march 8 1992 atmospheric waves become visible on radar images of the sea surface because they are associated with a varying wind field at the sea surface which modulates the sea surface roughness and thus the backscattered radar power the identification of the wave pattern visible on the ers 1 sar image as a sea surface manifestation of an atmospheric nonlinear wave disturbance has been possible because this disturbance was also captured by meteorological sensors mounted on an 80 m high meteorological mast located on the island of heligoland geophysical parameters characterizing the atmospheric wave disturbance are derived from the ers 1 sar image and from the in situ meteorological data the wave period in the reference frame moving with the average wind is 9 5 min the average wavelength is 2300 m and the propagation velocity is 4 5 4 9 m s 1 estimates of the amplitude of the wind speed fluctuations in the wave propagation direction derived from the meteorological measurements at heligoland and from the gray level variations in the sar image yield values between 1 3 and 3 0 m s 1 the experimental data are interpreted in terms of theories of atmospheric nonlinear gravity waves

on the discrimination of radar signatures of atmospheric gravity waves and oceanic internal waves on synthetic aperture radar images of the sea surface synthetic aperture radar sar images acquired over the ocean frequently show sea wave like patterns that have wavelengths well above those of ocean surface waves and that are sea surface signatures of oceanic internal waves oiws or of atmospheric gravity waves agws however it is often difficult to decide whether they result from the first or the second kind of waves which has led many investigators to misinterpret sar images of the sea surface based on solitary wave and radar imaging theories of agws and oiws we present criteria that help distinguish between them however there are cases where these criteria which are based solely on the shape and structure of the features visible on the sar images yield ambiguous results in these cases one must resort to additional information on the generation of agws and oiws which are listed in this paper

on the remote sensing of oceanic and atmospheric convection in the greenland sea by synthetic aperture radar 1 in this paper we discuss characteristic properties of radar signatures of oceanic and atmospheric convection features in the greenland sea if the water surface is clean no surface films or ice coverage oceanic and atmospheric features can become visible in radar images via a modulation of the surface roughness and their radar signatures can be very similar for an unambiguous interpretation and for the retrieval of quantitative information on current and wind variations from radar imagery with such signatures theoretical models of current and wind phenomena and their radar imaging mechanisms must be utilized we demonstrate this approach with the analysis of some synthetic aperture radar sar images acquired by the satellites ers 2 and radarsat 1 in one case an ers 2 sar image and a radarsat 1 scansar image exhibit pronounced cell like signatures with length scales on the order of 10 20 km and modulation depths of about 5 6 db and 9 10 db respectively simulations with a numerical sar imaging model and various input current and wind fields reveal that the signatures in both images can be explained consistently by wind variations on the order of 2 5 m s but not by surface current variations on realistic orders of magnitude accordingly the observed features must be atmospheric convection cells this is confirmed by visible typical cloud patterns in a noaa avhrr image of the test scenario in another case the presence of an oceanic convective chimney is obvious from in situ data but no signatures of it are visible in an ers 2 sar image we show by numerical simulations with an oceanic convection model and our sar imaging model that this is consistent with theoretical predictions since the current gradients associated with the observed chimney are not sufficiently strong to give rise to significant signatures in an ers 2 sar image under the given conditions further model results indicate that it should be generally difficult to observe oceanic convection features in the greenland sea with ers 2 or radarsat 1 sar since their signatures resulting from pure wave current interaction will be too weak to become visible in the noisy sar images in most cases this situation will improve with the availability of future high resolution sars such as radarsat 2 sar in fine resolution mode 2004 and terrasar x 2005 which will offer significantly reduced speckle noise fluctuations at comparable spatial resolutions and thus a much better visibility of small image intensity variations on spatial scales on the order of a few hundred meters index terms 3314 meteorology and atmospheric dynamics convective processes 4275 oceanography general remote sensing and electromagnetic processes 0689 4279 oceanography general upwelling and convergences 4255 oceanography general numerical modeling

coexistence of atmospheric gravity waves and boundary layer rolls observed by sar abstractboth atmospheric gravity waves agw and marine atmospheric boundary layer mabl rolls are simultaneously observed on an environmental satellite envisat advanced synthetic aperture radar asar image acquired along the china coast on 22 may 2005 the synthetic aperture radar sar image covers about 400 km 400 km of a coastal area of the yellow sea the sea surface imprints of agw show the patterns of both a transverse wave along the coastal plain and a diverging wave in the lee of mount laoshan 1133 m peak which indicate that terrain forcing affects the formation of agw the agw have a wavelength of 8 10 km and extend about 100 km offshore model simulation shows that these waves have an amplitude over 3 km finer scale 2 km brushlike roughness features perpendicular to the coast are also observed and they are interpreted as mabl rolls the fft analysis shows that the roll wavelengths vary spatially the two way interactive triply nested grid 9 3 1 km weather research and forecasti

garnet u pb dating of the yinan au cu skarn deposit luxi district north china craton implications for district wide coeval au cu and fe skarn mineralization abstract several recent studies have shown that garnet u pb dating may potentially provide robust constraints on the ages of carbonatite alkaline magmatism and skarn ore formation here we present textural trace element and laser ablation inductively coupled plasma mass spectrometry u pb isotope data of garnet from the yinan au cu skarn deposit in luxi district eastern north china craton to place tight constraints on the timing of mineralization three hydrothermal andradite rich garnet samples jl 8 thz 38 and tj 13 collected respectively from jinlong tonghanzhuang and gongquan ore segments of the yinan au cu skarn deposit contain 2 31 10 36 ppm u and are characterized by flat time resolved depth profiles for u indicating that this element is hosted in crystallographic lattice in the garnets the positive correlation between u and lrees concentration suggests that the incorporation of u into the garnet is largely controlled by substitution mechanisms the three garnet samples yield weighted mean 206pb 238u dates of 127 3 ma 127 5 ma and 126 7 ma 2 respectively these ages are reproducible within analytical uncertainties and are consistent with a zircon u pb age of 129 2 ma of the ore related diorite intrusion and thus are interpreted as the age of au cu mineralization at yinan the results presented here when combined with existing isotopic age data demonstrate that au cu skarn mineralization throughout the southeastern luxi district occurred coevally in the early cretaceous and is genetically associated with the tongjing and jingchang granitic dioritic complexes the au cu mineralization and associated magmatism coincide in time with the iron skarn mineralization and associated magmatism 134 126 ma across the luxi district strongly suggesting a causal link between the district wide skarn mineralization and pervasive intermediate to felsic magmatism both are products of destruction of lithospheric mantle beneath the north china craton this study confirms that garnet u pb dating can be a robust geochronometer for garnet bearing hydrothermal deposits and can elucidate associated geological processes

atmospheric boundary layer rolls observed by the synthetic aperture radar aboard the ers 1 satellite two synthetic aperture radar sar images acquired by the european remote sensing satellite ers 1 over the jade weser estuary in the german bight of the north sea on january 2 and 20 1992 are analyzed the images show sea surface manifestations of atmospheric boundary layer rolls this is inferred from the orientation of the quasi periodic sea surface patterns which are aligned approximately with the wind direction from the ratio of the wavelength of the patterns to the height of the boundary layer and from the conditions encountered in the atmospheric boundary layer as measured quasi simultaneously by radiosondes the atmospheric boundary layer rolls were generated by a dynamic instability on january 2 and by a thermal instability on january 20 for the first time quantitative estimates of variations of the wind velocity at the sea surface associated with the atmospheric rolls are extracted from a spaceborne radar sar image it is shown that wind velocities derived from sar image intensity variations are in agreement with theoretical estimates

evolution of ore fluids in the donggou giant porphyry mo system east qinling china a new type of porphyry mo deposit evidence from fluid inclusion and h o isotope systematics abstract the donggou mo deposit in the eastern qinling area china is a giant porphyry system discovered based on a targeting concept by using the tectonic model for collisional orogeny metallogeny and fluid flow cmf model mo mineralization is associated with the donggou aluminous a type granite porphyry and was formed during the early cretaceous in a tectonic regime of continental extension the orebodies mainly occur as numerous veinlets in the host rocks hydrothermal ore forming processes include at least three stages characterized by veinlets of 1 quartz k feldspar minor molybdenite 2 quartz molybdenite beryl and 3 quartz carbonate fluorite three types of fluid inclusions fis are distinguished in quartz and beryl in stages 1 and 2 i e aqueous w type carbonic aqueous c type and solid bearing s type with only aqueous fis observed in stage 3 minerals s type fis contain variable daughter minerals including halite chalcopyrite calcite and an unidentified transparent crystal but only halite can dissolve during heating halite bearing s type fis are mainly homogenized by halite dissolution at 182 416 c corresponding to salinities of 30 9 49 2 wt nacl equiv minor halite bearing s type fis are homogenized to liquid at 190 360 c via vapor disappearance with salinities of 29 1 36 2 wt nacl equiv other fis in minerals of stages 1 2 and 3 are homogenized at temperatures of 341 550 c 220 440 c and 125 225 c with salinities of 8 0 18 3 5 3 16 8 and 0 5 7 3 wt nacl equiv respectively the estimated minimum trapping pressures are up to 141 mpa in stage 1 and up to 81 mpa in stage 2 respectively corresponding to an initial mineralization depth of no less than 5 km the quartz in veinlets yields 18 o values of 8 5 10 0 corresponding to 18 o h 2 o values of 2 9 to 5 9 while the d h 2 o values of fluid inclusions range from 59 to 82 these data suggest that the ore fluids forming the donggou deposit changed from high temperature high salinity co 2 rich magmatic to low temperature low salinity and co 2 poor meteoritic fluids via boiling and mixing resembling those of other magmatic hydrothermal systems in qinling orogen and dabie shan this supports the notion that the porphyry systems generated in a post collisional tectonic setting were initially co 2 rich as indicated by abundant c type and co 2 bearing s type fluid inclusions

genesis of the jinchanggouliang gold deposit chifeng china constraints from fluid inclusions and isotopic geochemistry abstract the jinchanggouliang gold deposit which located south of the hingan mongolian orogenic belt is a large gold deposit in the chifeng chaoyang region field evidence and petrographic observations indicate that the mineralization processes can be divided into three stages including milky or grey quartz stage i quartz pyrite stage ii quartz polymetallic sulfides stage iii five types of fis have been identified in the jinchanggouliang deposit 1 solid bearing inclusions type 1 liquid rich inclusions type 2 vapor rich inclusions type 3 pure vapor inclusions type 4 and co2 h2o inclusions type 5 the first stage contains mainly type 2 but also minor type 3 and 4 fis the fis display homogenization temperatures of 317 384 c and salinities of 4 0 12 5 wt nacl eq the stage ii contains all types of fis mainly type 2 less abundant type 3 and 5 rarely type 1 and 4 which show homogenization temperatures of 288 382 c and salinities of 1 6 41 4 wt nacl eq the types of fis in stage iii are the same as stage ii these fis yield the lowest homogenization temperatures of 245 363 c and salinities of 1 1 36 8 wt nacl eq the ore forming fluids are characterized by moderate high temperature and great fluctuating salinity magmatic hydrothermal fluids the type 2 and 3 fis commonly coexist with simultaneously trapped type 5 fis and the type 2 and 3 fis have similar homogenization temperatures but contrasting homogenization modes to the liquid and vapor respectively in the main mineralization stages which suggests fluid boiling occurred in these two stages combined with the previous h o isotopic data it can be concluded that the ore forming fluids are of granitic magmatic origin the s pb isotopes indicate that the ore materials were mainly derived from deep magma petrographic observations and microthermometric analysis indicating that fluid boiling was the main mineral precipitation mechanism and fluid boiling mainly occurred in the temperature range from 290 c to 370 c in general from the view of fluid inclusions and isotopes geochemistry the jinchanggouliang gold deposit is most probably a magmatic hydrothermal deposit

fluid evolution of the yuchiling porphyry mo deposit east qinling china the yuchiling mo deposit east qinling china belongs to a typical porphyry mo system associated with high k calc alkaline intrusions the pure co2 pc co2 bearing c aqueous h2o naci w and

immiscibility during mineralization of yinan au cu fe deposit shandong province evidence from fluid inclusions and h o isotopes the yinan skarn type au cu fe deposit occurs at the contact zone between the yanshanian intrusives and the neo archean cambrian sedimentary rocks hydrogen and oxygen isotopic geochemistry shows that the early ore forming fluids of the anhydrous skarn stage and the hydrous skarn magnetite stage were mainly derived from magmatic water whereas the late fluids of the quartz sulfide stage and the carbonate stage came mainly from magmatic water mixed with small amounts of meteoric water various types of fluid inclusions which include mainly vapor or liquid rich two phase aqueous inclusions daughter minerals bearing multiphase inclusions and co2 h2o inclusions subordinately liquid inclusions and vapor inclusions and minor melt inclusions are present in minerals of different stages the homogenization temperature of the aqueous fluid inclusions decreases from stage 520 430 through stage 430 340 and 250 190 to stage 190 130 the coexistence of melt inclusions with simultaneously trapped vapor or liquid rich two phase aqueous inclusions and daughter minerals bearing multiphase inclusions in garnet and epidote of stages and suggests an immiscibility between silicate melt and hydrothermal fluid in the quartz of stage the aqueous fluid inclusions with various vapor liquid ratios 10 or 65 commonly coexist with simultaneously trapped liquid inclusions vapor inclusions daughter minerals bearing multiphase inclusions and co2 h2o inclusions and different kinds of fluid inclusions have similar homogenization temperatures this indicates that boiling extensively took place at stage it is thus suggested that two kinds of immiscibility occurred in the process from magmatic crystallization and differentiation to hydrothermal mineralization in the yinan ore deposit the earlier immiscibility between silicate melt and hydrothermal fluid caused the escape of ore bearing fluids from the magma whereas the later immiscibility between gaseous and liquid phases boiling resulted in au cu fe mineralization

cretaceous cenozoic tectonic history of the jiaojia fault and gold mineralization in the jiaodong peninsula china constraints from zircon u pb illite k ar and apatite fission track thermochronometry the jiaojia fault jjf in the jiaodong area of eastern china is an important nne trending structure that is subsidiary to the regional tancheng lujiang tan lu fault zone and hosts 1200 t of gold reserves contained in disseminated and stockwork ore dominantly in the footwall of the fault we present new zircon u pb apatite fission track and illite k ar data along the jjf and have delineated its tectonic history focusing on its formation and reactivation zircon u pb dating shows that the shangzhuang granite is a composite body with ages between 132 1 and 127 1 ma illite k ar ages for the fault s gouge range from 83 2 to 68 2 ma and the measured apatite fission track ages for ores are between 55 and 21 ma previous zircon u pb geochronology and structural studies suggest that the jjf was originally activated in the jurassic during 160 150 ma as a sinistral fault the jjf was a normal fault in the early cretaceous due to nw se orientated tension and ne sw compression which lasted from 135 to 120 ma this was followed by sinistral strike slip faulting due to nw se compression and ne sw tension during 120 110 ma and it changed to normal displacement at ca 110 ma our apatite fission track data analysis and thermal modeling of representative samples suggest that there was a subsequent dextral reactivation of the fault at ca 55 ma previous age data of ca 130 110 ma for gold mineralization along the jjf coincides with the early cretaceous magmatism and is coeval with the transition from normal faulting to sinistral strike slip faulting of the jjf in early cretaceous which is interpreted to be due to changing direction of the subducting pacific plate

paleozoic multiple accretionary and collisional tectonics of the chinese tianshan orogenic collage abstract subduction related accretion in the junggar balkash and south tianshan oceans paleo asian ocean mainly in the paleozoic gave rise to the present 2400 km long tianshan orogenic collage that extends from the aral sea eastwards through uzbekistan tajikistan kyrgyzstan to xinjiang in china this paper provides an up to date along strike synthesis of this orogenic collage and a new tectonic model to explain its accretionary evolution the northern part of the orogenic collage developed by consumption of the junggar balkash ocean together with paleozoic island arcs northern ili issyk kul and chatkal located in the west which may have amalgamated into a composite arc in the paleozoic in the west and by addition of another two roughly parallel arcs dananhu and central tianshan in the east the western composite arc and the eastern dananhu and central tianshan arcs formed a late paleozoic archipelago with multiple subduction zones the southern part of the orogenic collage developed by the consumption of the south tianshan ocean which gave rise to a continuous accretionary complex kokshaal kumishi which separated the central tianshan in the east and other paleozoic arcs in the west from cratons tarim and karakum to the south cross border correlations of this accretionary complex indicate a general southward and oceanward accretion by northward subduction in the early paleozoic to permian as recorded by successive southward juxtaposition of ophiolites slices of ophiolitic melanges cherts island arcs olistostromes blueschists and turbidites which are mainly paleozoic in age with the youngest main phase being late carboniferous permian the initial docking of the southerly tarim and karakum cratons to this complicated late paleozoic archipelago and accretionary complexes occurred in the late carboniferous early permian in the eastern part of the tianshan and in the late permian in the western part which might have terminated collisional deformation on this suture zone the final stages of closure of the junggar balkash ocean resembled the small ocean basin scenario of the mediterranean sea in the cenozoic in summary the history of the altaids is characterized by complicated multiple accretionary and collisional tectonics

shrimp zircon u pb geochronology geochemistry and h o si s pb isotope systematics of the kanggur gold deposit in eastern tianshan nw china implication for ore genesis abstract the kanggur gold deposit is located in the southern margin of the central asia orogenic belt and in the western segment of the kanggur huangshan ductile shear belt in eastern tianshan northwestern china the orebodies of this deposit are hosted in the lower carboniferous volcanic rocks of the aqishan formation and mainly consist of andesite dacite and pyroclastic rocks the shrimp zircon u pb age data of the andesite indicate that the volcanism in the kanggur area might have occurred at ca 339 ma in the early carboniferous and that the mineralization age of the kanggur gold deposit was later than the age of volcanic rocks in the area geochemically the andesite rocks of the aqishan formation belong to low tholeiite and calc alkaline series and display relative depletions in high field strength elements hfses i e nb ta and ti the 18 o w and d w values vary from 9 1 to 3 8 and 66 0 to 33 9 respectively indicating that the ore forming fluids were mixtures of metamorphic and meteoric waters the 30 si values of 13 quartz samples range from 0 3 to 0 1 with an average of 0 15 and the 34 s values of 18 sulphide samples range from 0 9 to 2 2 with an average of 0 54 the 206 pb 204 pb 207 pb 204 pb and 208 pb 204 pb values of 10 sulphide samples range from 18 166 to 18 880 15 553 to 15 635 and 38 050 to 38 813 respectively showing similarities to orogenic pb these values are consistent with those of the andesite from the kanggur area suggesting a common lead source all of the silicon sulphur and lead isotopic systems indicate that the ore forming fluids and materials were mainly derived from the aqishan formation and that the host volcanic rocks of the aqishan formation probably played a significant role in the kanggur gold mineralization integrating the data obtained from studies on geology geochronology petro geochemistry and h o si s pb isotope systematics we suggest that the kanggur gold deposit is an orogenic type deposit formed in eastern tianshan orogenic belt during the permian post collisional tectonism

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

ocean surface currents from avhrr imagery comparison with land based hf radar measurements we focus on inverting the surface temperature or heat equation to obtain the surface velocity field in the coastal ocean and compare the results with those from the maximum cross correlation mcc technique and with the in situ velocity fields measured by the rutgers university coastal ocean dynamics radar codar when compared with codar fields velocities from the heat equation and mcc have comparable accuracies but the heat equation technique better resolves the finer scale flow features we use the results to directly calculate the surface divergence and vorticity this is possible because we convert the traditionally underdetermined heat inversion problem to an overdetermined one without constraining the velocity field with divergence vorticity or energy statements because no a priori assumptions are made about the vorticity it can be calculated directly from the velocity results the derived vorticity field has typical open ocean magnitudes 5 times 10 5 s and exhibits several structures a warm core ring gulf stream filament and a diverging flow consistent with the types of flows required to kinematically deform the sea surface temperature patterns into the observed configurations

a new interpretation of multifrequency multipolarization radar signatures of the gulf stream front radar signatures which are observed on sir c x sar multifrequency multipolarization synthetic aperture radar images of the gulf stream off the u s east coast are compared with results of simulations with a numerical radar imaging model based on in situ data current and wind variations are included into the model as well as a variation of the thermal stability of the marine atmospheric boundary layer across the gulf stream front according to our model predictions all of these parameter variations can cause radar signatures of similar shape and modulation depth but due to specific dependencies of radar signatures on variations of surface currents and winds we show that it is possible to distinguish between radar signatures of oceanic and atmospheric origin in multifrequency multipolarization images and to estimate the corresponding current and wind variations independently for one set of radar images we derive a most likely scenario of oceanic and atmospheric parameters during the time of the image acquisition for which good overall agreement between observed and simulated radar signatures is obtained at most radar channels

synergistic use of satellite observations and numerical weather model to study atmospheric occluded fronts synthetic aperture radar sar images reveal the surface imprints of atmospheric occluded fronts an occluded front is characterized as a low wind zone located between and within two zones of higher winds blowing in the opposite directions on the left and right sides of the occluded front a group of four sar images reveal that the width of an individual occluded frontal zone and the wind magnitudes outside fronts vary greatly from case to case in this paper we performed a case study to analyze an occluded front observed by an environmental satellite envisat advanced sar and ascat scatterometer along the west coast of canada on november 24 2011 the two way interactive triply nested grid 9 3 1 km weather research and forecasting wrf model was utilized to simulate the evolution of the occluded front the occluded front moved toward the east during a 24 h model simulation and the movement between 18 00 and 21 00 utc matched the occluded front positions derived from the concurrently collected surface weather maps from the national oceanic and atmospheric national weather service archives the wrf simulated low wind zone associated with the occluded front and ocean surface wind speed match well with the sar and scatterometer wind retrievals high wind outside the front zone became weaker during the front evolution whereas the width of the occluded frontal zone was contracted laterally analysis of the wrf model derived potential temperature field suggests that the occlusion process occurred below the 800 mb level the structure of the occluded front studied here not only follows the conventional conceptual model and also supports the findings of a novel wrap up conceptual model for an atmospheric frontal occlusion process

airborne synthetic aperture radar imagery of atmospheric gravity waves we analyze the oceanic imprints of atmospheric internal gravity waves detected in airborne synthetic aperture radar sar images collected off the west coast of vancouver island british columbia in june 1990 a sequence of sar images taken over a period of 2 5 hours reveals that the waves traveled with group velocities of 3 6 m s 1 toward the northwest counter to the 10 m s 1 surface winds wave crests were oriented normal to the coast and had lateral extents of several tens of kilometers observed wavelengths ranged from 1 2 to 2 3 km while calculated wave periods ranged from 3 to 8 min a comparison of the observed wave properties with values derived from a simple three layer density model of the troposphere suggest that the waves were low mode oscillations trapped within a 0 75 km thick temperature inversion overlying a 1 km thick weakly stratified marine boundary layer wave propagation was counter to the wind shear within the inversion layer generation of the internal wave groups appears to have occurred near the southern boundary of the stable marine air mass where it bordered a convectively active air mass that was intruding northward along the coast

zircon u pb geochronology geochemistry and sr nd hf isotopes of granitoids in the yulekenhalasu copper ore district northern junggar china petrogenesis and tectonic implications abstract the yulekenhalasu porphyry copper deposit is located in the kalaxiange er metallogenic belt in northern junggar china we present the results from zircon u pb geochronology and geochemical and sr nd hf isotope analyses of the granitoids associated with the ore deposits with a view to constrain their petrogenesis and tectonic setting the granitoids consist of quartz diorite diorite porphyry porphyritic monzonite and quartz porphyry emplaced at 382 379 375 374 and 348 ma respectively which span late devonian to early carboniferous ages the ore bearing intrusion is mainly diorite porphyry with subordinate porphyritic monzonite the late devonian intrusions are characterized by sio2 contents of 54 5 64 79 wt na2o contents of 3 82 8 24 wt enrichment in na light rare earth elements lrees and large ion lithophile elements they also display relative depletion in y ba p nb ta and ti and weak negative eu anomalies eu 0 6 0 87 the early carboniferous quartz porphyry is characterized by high sio2 content 72 26 73 35 wt enrichment in lrees k and sr and relative depletion in y 10 82 12 52 ppm and yb 1 06 1 15 ppm the late devonian and early carboniferous granitoids are characterized by positive end t values 5 2 10 1 one sample at 1 9 positive ehf t values 7 46 18 45 low 87sr 86sr i values 0 70363 0 70476 and young crustal residence ages these data indicate that the sources of the granitoids were mainly mantle derived juvenile rocks geochemical and nd sr hf isotopic data demonstrate that the late devonian granitoids formed in an oceanic island arc and they were formed from different sources among which the mineralized diorite porphyry might have originated from a mixed slab derived and mantle wedge melt source the early carboniferous quartz porphyry was likely emplaced in a mature island arc environment and was probably derived from juvenile crust

sequence stratigraphy provenance c and o isotopic composition and correlation of the late paleoproterozoic early mesoproterozoic upper hornby bay and lower dismal lakes groups nwt and nunavut abstract late paleoproterozoic basins of canada s north including the thelon athabasca and hornby bay basins can be broadly correlated based on similarities in age sequence stratigraphy paleocurrents and detrital zircon provenance but their detailed evolution is poorly understood and their age and lateral equivalencies are poorly constrained this study contributes to the understanding of sedimentary basins during a critical interval of time representing the latest stages of amalgamation of the supercontinent laurentia nuna through a detailed study of the hornby bay basin the hornby bay basin strata have been divided into four unconformity bounded subsequences a1 a2 a3 a4 that belong to the first of three unconformity bounded post hudsonian proterozoic stratigraphic packages in northwestern canada subsequences a2 1600 ma and a3 analysis of sm nd isotopes on mudrocks yielded isotopic compositions in the range 8 2 to 2 3 nd 1600 ma in subsequence a2 and 9 8 to 5 0 nd 1400 ma in subsequence a3 an nd versus time graph illustrates two distinct groupings that plot within known isotopic evolution fields of the taltson thelon tectonic zone and the great bear magmatic zone sediment provenance was strongly influenced by the paleoproterozoic forward orogeny but there are no significant changes in sedimentary provenance across the a2 a3 sequence boundary stable isotope analyses of c and o in the dolomitic east river formation of subsequence a2 reveal a relatively monotonous signal with an average of 0 5 13 c and 8 76 18 o which is consistent with global values of other late paleoproterozoic carbonate successions enriched mn values and depleted sr values however suggest that the east river carbonate rocks experienced some degree of meteoric alteration it is unknown how much this alteration affected stable isotope compositions based on similarities in sedimentary provenance age and sequence stratigraphy subsequence a2 of the hornby bay group is correlated with the wernecke supergroup yukon the latter is interpreted to represent the deep water distal equivalent of the upper hornby bay group in a westward deepening basin deposition of subsequence a2 is recorded across north america and is mirrored by deep water sedimentation along the eastern margin of the north australian craton the tectonic evolution of subsequence a2 in laurentia is therefore remarkably similar to that of the north australian craton up to 1600 ma the age of the forward orogeny and this has implications for interpretation of the latest stages of accretion of the supercontinent nuna

an improved composite surface model for the radar backscattering cross section of the ocean surface 2 model response to surface roughness variations and the radar imaging of underwater bottom topography in the companion paper we have presented an improved composite surface model for the calculation of normalized radar backscattering cross sections nrcs of the ocean surface the proposed model accounts for the impact of the full two dimensional ocean wave spectrum on the radar backscatter and was shown to reproduce measured absolute nrcs values for a variety of radar configurations and wind speeds satisfactorily after some reasonable tuning of the input ocean wave spectrum this paper focuses on the modulation of the nrcs in the presence of spatially varying surface currents first the sensitivity of the nrcs to intensity variations of different ocean wave spectral components is investigated then the hydrodynamic modulation of the wave spectrum over underwater bottom topography in tidal waters is computed in different ways and the resulting radar signatures are discussed the composite surface model yields comparable radar signatures at high 10 ghz x band and low 1 ghz l band radar frequencies which is in much better agreement with experimental results than the predictions of a first order bragg scattering model on the other hand measured variations of the nrcs at high radar frequencies appear to be still underestimated in some cases which may be due to shortcomings of our description of the wave current interaction by conventional weak hydrodynamic interaction theory possible improvements of the theory are discussed and requirements for future experiments are formulated

on polarimetric characteristics in sar images of mesoscale cellular convection in the marine atmospheric boundary layer 1 convection is an important phenomenon in the marine atmospheric boundary layer mabl previous spaceborne radar studies of such have been limited to single polarization data and therefore their focus was on the variation in intensity of the radar return which was constrained by the existence of a single polarization image pattern representing different atmospheric and oceanic phenomena in this paper we study the polarimetric characteristics of mesoscale cellular convection mcc in the mabl using high resolution data from fully polarimetric hh vv hv and vh radarsat 2 rs 2 synthetic aperture radar sar images in conjunction with closely collocated mesoscale atmospheric model simulations to identify the mcc signatures to compare the polarimetric characteristics of mcc with those of the ocean surface our analysis also includes 641 open ocean surface quad polarization rs 2 sar images collocated with 52 national data buoy center buoys the open ocean surface sar images exhibit different polarimetric characteristics from those of mcc thus we differentiate mcc from other open ocean phenomena based on identifiable polarimetric sar characteristics