mafic and felsic magma interaction in granites the hercynian karkonosze pluton sudetes bohemian massif the hercynian post collisional karkonosze pluton contains several lithologies equigranular and porphyritic granites hybrid quartz diorites and granodiorites microgranular magmatic enclaves and composite and lamprophyre dykes field relationships mineralogy and majorand trace element geochemistry show that 1 the equigranular granite is differentiated and evolved by small degrees of fractional crystallization and that it is free of contamination by mafic magma 2 all other components are affected by mixing the end members of the mixing process were a porphyritic granite and a mafic lamprophyre the degree of mixing varied widely depending on both place and time all of the processes involved are assessed quantitatively with the following conclusions most of the pluton was affected by mixing implying that huge volumes 475 km of mafic magma were available this mafic magma probably supplied the additional heat necessary to initiate crustal melting part of this heat could have also been released as latent heat of crystallization only a very small part of the karkonosze granite escaped interaction with mafic magma specifically the equigranular granite and a subordinate part of the porphyritic granite minerals from these facies are compositionally homogeneous and or normally zoned which together with geochemical modelling indicates that they evolved by small degrees of fractional crystallization 520 accessory minerals played an important role during magmatic differentiation and thus the fractional crystallization history is better recorded by trace rather than by major elements the interactions between mafic and felsic magmas reflect their viscosity contrast with increasing viscosity contrast the magmatic relationships change from homogeneous hybrid quartz diorites granodiorites to rounded magmatic enclaves to composite dykes and finally to dykes with chilled margins these relationships indicate that injection of mafic magma into the granite took place over the whole crystallization history consequently a long lived mafic source coexisted together with the granite magma mafic magmas were derived either directly from the mantle or via one or more crustal storage reservoirs compatible element abundances e g ni show that the mafic magmas that interacted with the granite were progressively poorer in ni in the order hybrid quartz dioritescgranodioritescenclavesccomposite dykes this indicates that the felsic and mafic magmas evolved independently which in the case of the karkonosze granite favours a deep seated magma chamber rather than a continuous flux from mantle two magma sources mantle and crust coexisted and melted almost contemporaneously the two reservoirs evolved independently by fractional crystallization however mafic magma was continuously being intruded into the crystallizing granite with more or less complete mixing several lines of evidence e g magmatic flux structures incorporation of granite feldspars into mafic magma feldspar zoning with fluctuating trace element patterns reflecting rapid changes in magma composition indicate that during its emplacement and crystallization the granite body was affected by strong internal movements these would favour more complete and efficient mixing the systematic spatial temporal association of lamprophyres with crustal magmas is interpreted as indicating that their mantle source is a fertile peridotite possibly enriched metasomatized by earlier subduction processes

apatite as a monitor of late stage magmatic processes at volcan irazu costa rica apatite phenocrysts from the 1963 and 1723 eruptions of irazu volcano costa rica record a volatile evolution history that confirms previous melt inclusion studies and provides additional information concerning the relative and absolute timing of subvolcanic magmatic events measurements of h cl and f by secondary ion mass spectrometry reveal multiple populations of apatite in both 1723 and 1963 magmas assuming nominal apatite melt partition coefficients allows us to compare the pattern of melt inclusions and apatites in ternary space demonstrating the fidelity of the record preserved in apatite and revealing a complex history of magma mixing with at least two components the preservation of heterogeneous populations of apatite and of internally heterogeneous crystals requires short timescales days to years for these magmatic processes to occur

complex zoning in apatite from the idaho batholith a record of magma mixing and intracrystalline trace element diffusion apatite crystals in a sample of biotite granodiorite from the idaho batholith display complex chemical zoning characterized by abrupt changes in ree y si content more subtle variations in s na la yb and mn contents and petrographic evidence for multiple episodes of partial resorption the zoning is attributed to changes in melt composition resulting from magma mixing and differentiation although the possibility that some rounded cores may be inherited cannot be disproved high s contents in apatite cores and the presence of an included anhydrite grain indicate crystallization from an oxidized host magma divalent cations that occupy the apatite ca sites sr mn fe show evidence of having been redistributed between zones by intracrystalline diffusion whereas cations that participate in coupled substitutions involving the tetrahedral site si y ree na s were not readily redistributed the main ree substitution in this case is ree super 3 si super 4 ca super 2 p super 5 and ree diffusion is rate limited by slow si diffusion however exchange of lree e g lasm sub 1 on the ca sites does not involve si and proceeds more rapidly resulting in homogenization of la sm between zones within individual crystals relative diffusion rates inferred from zoning profiles in this study are mn sr fe and lasm sub 1 are faster than na s and layb sub 1 which are faster than si these data imply that ree patterns can be decoupled from ree abundances during diffusion and that even apatite zones or cores that appear sharply bounded in backscattered electron images may not retain their original chemical or sr nd isotopic traits

variable parent magmas and recharge regimes of the parinacota magma system n chile revealed by fe mg and sr zoning in plagioclase abstract zoning patterns of an content and fe mg and sr concentrations in plagioclase phenocrysts in andesites from parinacota volcano n chile reflect alternating recharge events with two chemically distinct mafic magmas these magmas are characterized by low and high sr contents similar to two recent mafic flank eruptions one end member basaltic andesite shows large sr enrichment and heavy rare earth depletions and thus equilibrated with lower crustal rocks at depth where plagioclase high sr is unstable and garnet high hree y is stable a second end member magma is lower in sr ba contents and has ree patterns typical for parent magmas elsewhere in the central andes the number of recorded recharge events increases after a catastrophic sector collapse and during the subsequent rebuilding of the stratocone variations of an fe and mg contents and morphology of zones suggest also changes in water pressure including decompression under water under saturated and water saturated conditions evidence for decompression is more present in post collapse samples suggesting that the change in the volcano dynamics involves changes in magma chamber location this shows the importance of the cone collapse event in the volcano s magmatic evolution we propose that both end members are only seen at the surface of parinacota volcano because of the particular dynamics of this volcanic system and that similar processes might occur in other volcanic centres of the central volcanic zone

monazite to the rescue u th pb dating of the intrusive history of the composite karkonosze pluton bohemian massif the large 700 km2 composite karkonosze krkonose pluton in the west sudetes on the border between poland and the czech republic consists mainly of porphyritic and equigranular granitoids but contains a range of lithologies from lamprophyre to leucogranite the absolute age and duration of the plutonism have proved difficult to determine previous age measurements by rb sr ar ar and u pb range from 330 to 290 ma with more recent results converging to 320 300 ma dating of zircon and monazite from samples of a variety of major and minor lithologies by sims u th pb several from the geochemical study of slaby and martin 2008 has narrowed the possible age range further u pb ages measured on eight of ten zircon and monazite samples are in the range 314 311 ma zircon ages measured on the two major types of porphyritic granitoid are 313 3 and 311 4 ma and monazite ages are 312 2 313 3 and 311 3 ma monazite from one hybrid granitoid has an age of 314 3 ma and zircon from another an age of 314 4 ma zircon from a composite dyke has an age of 311 6 ma the monazite u pb age of an equigranular granite at 318 6 ma is consistent with geological evidence that it is older than the porphyritic granitoids but because of the relatively large uncertainties is not conclusive zircon from one microgranular enclave is anomalously young 302 4 ma evidence is mounting that the main porphyritic granitoids hybrid granitoids and composite dykes were emplaced within a short time interval between 314 4 and 311 3 ma given the uncertainties emplacement of these units could have been effectively simultaneous the larger difference between the ages from the equigranular granite and microgranular enclave however indicates that the whole karkonosze thermal episode possibly lasted as long as 15 ma

apatite composition tracing petrogenetic processes in transhimalayan granitoids apatites crystallized from different types of igneous rocks show significant variations in the abundances of some minor and trace elements in this study electron probe microanalysis and laser ablation inductively coupled plasma mass spectrometry were used to determine the concentrations of 25 minor and trace elements in apatite separated from three principal rock types of thetranshimalayan igneous plutonic suite s type granites the i type gangdese batholith and postcollisional adakites f mn sr and rare earth elements ree in apatite vary systematically with the composition of the host magma and thus have high potential as petrogenetic tracers more specifically the f and mn contents of apatite can be used as an indicator of magma aluminosity or differentiation index combined with sr and ree data which show significant variations in apatite from different rock types these elements are useful for constructing discrimination diagrams this study also reveals that apatite has the capacity to retain geochemical information about the host magma through the course of magmatic evolution systematic variations of sr and ree in apatite with bulk rock aluminosity are the results of partition competition with pre existing and coexisting major and accessory minerals in silicate melts and thus are useful for more detailed investigations of petrogenetic processes such as fractional crystallization and magma mixing which is signaled by inconsistent eu anomalies sr abundances and ree patterns relative to bulkrock compositions

is there a relationship between magmatic fabrics and brittle fractures in plutons a view based on structural analysis anisotropy of magnetic susceptibility and thermo mechanical modelling of the tanvald pluton bohemian massif abstract the present study focuses on the thermal and mechanical aspects of cooling of plutonic systems with respect to their internal structure analysis of the tanvald pluton and the nearby liberec granite the krkonose jizera plutonic complex bohemian massif using the anisotropy of magnetic susceptibility ams method indicates the decoupled magnetic fabrics formed by different processes in these two plutons two regional sets of vertical fractures cut across the plutons and their host rocks they are interpreted as having been formed as opening mode fractures joints after emplacement and cooling our thermo mechanical finite element modelling indicates that the thermal stresses within the tanvald pluton were compressive and that fracture criteria were not met during pluton cooling these results imply that the emplacement depth and confining pressure significantly affect the state of stress within a pluton during cooling and may play a crucial role in the formation of early fractures in plutons consequently the formation of early fractures during pluton cooling is driven by external conditions overriding the role of internal magmatic fabrics we argue that no genetic geometric or temporal correlation can exist between magmatic fabrics and fractures in granitoid plutons and thus that the original concept of hans cloos based on fabric joints relationships should be reconsidered instead an alternative classification of fractures in plutons should include cooling fractures syntectonic fractures uplift fractures and post uplift fractures

mafic magmatic enclaves and mafic rocks associated with some granitoids of the central sierra nevada batholith california nature origin and relations with the hosts abstract the calc alkaline granitoids of the central sierra nevada batholith are associated with abundant mafic rocks these include both country rock xenoliths and mafic magmatic enclaves mme that commonly have fine grained and less commonly cumulate textures scarce composite enclaves consist of either xenoliths enclosed in mme or of mme enclosed in other mme with different grain size and texture enclaves are often enclosed in mafic aggregates and form meter size polygenic swarms mostly in the margins of normally zoned plutons enclaves may locally divert schlieren layering mafic dikes which also occur in swarms are undisturbed composite or largely hybridized in central sierra nevada with the exception of xenoliths that completely differ from the other rocks host granitoids mafic aggregates mme and some composite dikes exhibit a bulk compositional diversity and at the same time important mineralogical and geochemical including isotopic similarities mme and host granitoids display distinct major and trace element compositions however strong correlations between mme host granitoid pairs indicate interactions and parallel evolution of mme and enclosing granitoid in each pluton identical mafic mineral compositions and isotopic features are the result of these interactions and parallel evolution mafic dikes have broadly the same major and trace element compositions as the mme although variations are large between the different dikes that are at distinctly different stages of hybridization and digestion by the host granitoids the composition of the granitoids and various mafic rocks reflects three distinct stages of hybridization that occurred respectively at depth during ascent and emplacement and after emplacement the occurrence and succession of hybridization processes were tightly controlled by the physical properties of the magmas the sequential thorough or partial mixing and mingling were commonly followed by differentiation and segregation processes unusual mme that contain abundant large crystals of hornblende resulted from disruption of early cumulates at depth whereas those richer in large crystals of biotite were formed by disruption of late mafic aggregates or schlieren layerings at the level of emplacement mme and host granitoids are considered cogenetic because both are hybrid rocks that were produced by the mixing of the same two components in different proportions the felsic component was produced by partial melting of preexisting crustal materials whereas the dominant mafic component was probably derived from the upper mantle however in the lack of a clear mantle signature the origin of the mafic component remains questionable

apatite chemical composition determined by electron microprobe and laser ablation inductively coupled plasma mass spectrometry as a probe into granite petrogenesis abstract major minor and trace element abundances in apatites from various i and s type igneous and sedimentary granites of the lachlan fold belt have been determined using electron microprobe and laser ablation inductively coupled plasma mass spectrometer the results show that apatite can accommodate many minor and trace elements whose concentrations and ratios are relatively sensitive to factors controlling many of the fundamental differences between i and s type granites apatites from s type granites generally have higher f but lower cl contents than those from i type granites which is ascribed mainly to the loss of cl during the weathering processes forming the source rocks of s type granites although fractional crystallisation can cause significant enrichment in f as well high mn and fe contents in apatites from s type granites and high s and as abundances in apatites from mafic i type granites result from different oxygen fugacities and degrees of al saturation or aluminosity between metaluminous mafic i type magmas and peraluminous s type and felsic i type magmas there are systematic and distinctive differences in absolute rare earth element ree abundances ree distribution patterns and element ratios e g la y sm nd etc between apatites from different types of granite the strong eu depletion that characterises apatites from s and felsic i type granites is interpreted here to be a result of the uniqueness of crystal chemistry of apatite and high eu2 eu3 ratios in s type and felsic i type magmas which are more reduced and peraluminous than mafic i type magmas strong ree la to eu and th enrichment in apatites from mafic i type granites and marked nd depletion in apatites from most s type and felsic i type granites are caused by the precipitation and fractionation of monazite in the parental magmas of the latter rocks substitution mechanisms are responsible for high na in apatites from s type and felsic i type granites and for high si in apatites from mafic i type granites and may also have important effects on ree partitioning between apatite and melt thus apatite chemistry can be used as an excellent indicator of granite petrogenesis the results have important implications for identifying different types of granite and are potentially significant for determining the provenance of sedimentary rocks

the viscosity of latitic melts from lipari aeolian islands italy inference on mixing mingling processes in magmas abstract the viscosity of latitic melts occurring as enclaves in the rhyolitic lava flow of rocche rosse rr lipari aeolian islands italy has been measured in the high t range 1323 1473 k for a dissolved water content varying from 1 23 to 4 39 wt measurements were performed by the falling sphere method in an internally heated gas pressure vessel as expected the viscosity of latite decreases with increasing water content and temperature no pressure effect was detected between 200 and 500 mpa combining the new viscosity data for hydrous melts with data for dry latite of similar base composition giordano d mangiacapra a potuzak m russell j k romano c dingwell d b di muro a 2006 an expanded non arrhenian model for silicate melt viscosity a treatment for metaluminous peraluminous and peralkaline liquids chemical geology 229 42 56 we propose an empirical equation to estimate the viscosity of latitic melts as a function of temperature and water content over the range 101 to 1012 pa s the obtained relationship reproduces the experimental data with a 1 standard deviation of 0 22 log units however the empirical model is not constrained by data for hydrous melts at high viscosity and therefore it can only be used at low temperatures for water poor melts the viscosity data were used to model mixing mingling processes between latitic and rhyolitic magmas at conditions relevant for the rocche rosse rr lipari aeolian islands and la fossa cone 1888 1890 lfc vulcano aeolian islands eruptions the results demonstrate that the ratio between mafic and silicic end members is the main parameter governing mixing mingling interactions between magmas this study suggests a faster ascent of magma underneath vulcano compared to lipari which may be taken into account in hazard forecasting

the effect of hawai i s big island on track and structure of tropical cyclones passing to the south and west abstractthe effect of the big island of hawai i on tropical cyclone tc track and structure is investigated using the weather research and forecasting wrf model the high 4000 m mountains of the big island modulate lower tropospheric flow in such a way that it can influence tcs hundreds of kilometers away from the island when a tc approaches from the east the blocking of lower tropospheric flow leads to a slowing of the tc s movement as a tc passes close to the south side of the big island it deviates southward the tc core convection and winds can become axisymmetric because of the blocking of the stronger northeasterly flow to the north of the storm the authors hypothesize that this axisymmetrization led to the unexpected eye formation of hurricane flossie 2007 just southeast of the big island as a tc moves into the lee southwest side of the big island the flow associated with the island wake leads to a track deviated to the right the hurricane dot 1959 simulations suggest that this

magmatic zoning in apatite a monitor of porosity and permeability change in granites apatites from the shap granite northern england are strongly zoned reflecting multiple generations of growth and dissolution such chemical zoning is most readily displayed in cathodoluminescence images and correlates well with trace element variation determined using la icp ms analyses the zoned apatites provide a detailed record of the changing scales of permeability during progressive crystallisation within the magma chamber early periods of apatite growth are preserved within cores and represent both early growth within a magma chamber dominated by vigorous mixing processes and inherited grains with significantly different chemistries the main phase of apatite growth within the magma was strongly controlled by the presence of adjacent biotite phenocrysts and is characterised by fine scale oscillatory zoning followed by the growth of a thin rim of relatively uniform composition the chemical evolution of the later phases of apatite growth and the stratigraphy of the zoning appear to record late stage crystallisation within progressively more isolated interstitial melt pockets

interactions between rhyolitic and basaltic melts unraveled by chaotic mixing experiments abstract magma mixing may operate at any stage in the evolution of a magmatic system the development of mixing is strongly controlled by fluid dynamics and its understanding requires a comprehensive physico chemical approach in order to identify and interpret its occurrence in nature here we experimentally study the physical and chemical interplays during the mixing of basaltic and rhyolitic natural melts from the snake river plains usa in particular we present the results of the first high temperature mixing experiments performed under controlled chaotic dynamic conditions providing a new methodological approach to constrain the complexities of the mixing process between natural silicate melts the mixing process is initially governed by the dynamics of stretching and folding of the melts producing alternating flow bands these bands increase the contact area between the end members which subsequently enhance chemical exchanges and thus contribute to the generation of regions with variable degrees of hybridization we quantified the mobility of major and trace elements across contact areas and analyzed the concentration variance decay induced by chemical diffusion the analysis shows that elements diffuse with different efficiencies as the chemical gradient evolves and therefore the achievement of hybrid compositions contrasts between elements the approach introduced in this study can in principle be applied to mixing trends observed in nature in order to estimate the time scales and degree of magma mixing evidenced across volcanic rocks deposits

the mixing of magmas in plutonic and volcanic environments analogies and differences abstract magma mixing processes have been widely recognized in both the plutonic and volcanic environments but the quality and quantity of information that can be extracted from the two environments are substantially different understanding the advantages and limits associated with the study of plutonic and volcanic rocks is essential to establish precise methodological approaches to build the most complete conceptual model by merging information from these two complementary igneous environments in this work we review magmatic interaction processes in the plutonic and volcanic environments by considering several aspects of these geological phenomena in particular we first briefly report on the structural and geochemical evidence for magma mixing in both plutonic and volcanic rocks with the aim to provide a general picture of this natural phenomenon successively we discuss some recent results about magma mixing achieved using the concepts from chaos theory and discuss their potential impact on magma differentiation finally we attempt to build a general picture of this igneous process by merging present day information from both the plutonic and volcanic environments it emerges from the general picture that the time spent by the magmatic system in the molten or partially molten state is the crucial factor for the preservation of the fingerprints of magma mixing in the two environments we propose a conceptual model that may be useful to understand what kind of information we can obtain from volcanic and plutonic rocks and ultimately to maximize our knowledge about magma mixing

trace element partitioning at conditions far from equilibrium ba and cs distributions between alkali feldspar and undercooled hydrous granitic liquid at 200 mpa this study examines the effects of increasing supersaturation attained by single step liquidus undercooling t on the partitioning of barium and cesium between potassic alkali feldspar afs and hydrous granitic liquid at 200 mpa the investigation is motivated by trace element distribution patterns in granitic pegmatites which cannot be simulated by fractionation models using equilibrium partition coefficients and thus its purpose is to assess if how and why partition coefficients for compatible and incompatible trace elements may vary when crystal growth commences far from the crystal melt equilibrium boundary barium expands the liquidus stability field of potassic feldspar to higher temperatures such that liquidi for the ba rich 0 5 wt bao compositions used are 100 c higher than for ba absent analogues at low degrees of undercooling t 50 c values of dbaafs m 10 20 fall within the range of previous investigations as do values of dcsafs m 0 10 from experiments at all temperatures progressively greater undercooling is manifested in the run products by increasingly skeletal to cuneiform crystal morphologies increased compositional zonation of afs and the development of compositional boundary layers in glass whereas the partitioning behavior of cs incompatible is not measurably affected strong undercooling apparently causes the partitioning of ba highly compatible to deviate from equilibrium behavior feldspars produced by strong undercooling t 100 c are heterogeneous such that dbaafs m versus k k na varies linearly between the average value at 850 c and the equilibrium value appropriate to the temperature of growth hence high supersaturation accompanying undercooling produces feldspar compositions by isothermal growth which record a vestige of the liquid line of descent i e an ontogeny within zoned crystals which approximately tracks the feldspar liquidus from high temperature to the final low temperature of actual crystal growth such zoning patterns may mimic normal patterns produced by fractionation with decreasing temperature under near equilibrium near liquidus conditions increasing fluorine contents tend to exacerbate the effects of undercooling by inhibiting feldspar nucleation causing both k k na ratios and compatible trace element partitioning behavior in feldspar to deviate from equilibrium values this effect continues until nucleation lag is overcome whereupon a period of rapid growth from supersaturated liquid follows which is similar to that in f absent compositions electronic supplementary material to this paper can be obtained by using the springer link server located at http dx doi org 10 1008 s00410 002 425 y

the tepla saxothuringian suture in the karkonosze izera massif western sudetes central european variscides the southern and eastern karkonosze izera massif northern bohemian massif exposes blueschist facies rocks and morb type magmatic complexes during late devonian to early carboniferous times these were overthrust within a nappe pile toward the nw onto the pre variscan saxothuringian basement composed of the izera kowary metagranitoids and their envelope the lowermost nappe or parautochthonous unit of the pile is the low grade metamorphosed jest d complex comprising a devonian to early carboniferous sedimentary succession of the saxothuringian passive margin this is tectonically overlain by the south karkonosze complex which represents ordovician silurian volcano sedimentary infill of the saxothuringian basin affected by late devonian hp metamorphism the uppermost nappe is the early palaeozoic epidote amphibolite grade leszczyniec morb like complex cropping out on the eastern margin of the karkonosze izera massif it probably represents a fragment of obducted saxothuringian basin floor the nappe pile was stacked beneath the overriding upper plate margin now concealed below the intra sudetic basin and hypothesized to represent a fragment of the tepla barrandian terrane the nappe stacking triggered by buoyancy controlled upward extrusion of the subducted continental slab was the main mechanism for the exhumation of hp rocks the final stages of the nw ward nappe stacking were accompanied and followed by se directed early carboniferous extensional collapse the lower plate of the suture zone was uplifted at that time and intruded by the 330 ma old nearly undeformed karkonosze granite pluton as a result of the collapse the tepla barrandian upper plate was downthrown on shear zones and brittle faults and buried under several km thick synorogenic late tournaisian through namurian and post orogenic late carboniferous early permian succession of the intra sudetic basin the south and east karkonosze suture most probably is a fragment of the tepla saxothuringian munchberg tepla suture belt known from the western bohemian massif

jurassic cooling ages in paleozoic to early mesozoic granitoids of northeastern patagonia 40ar 39ar 40k 40ar mica and u pb zircon evidence u pb shrimp zircon crystallization ages and ar ar and k ar mica cooling ages for basement rocks of the yaminue and nahuel niyeu areas in northeastern patagonia are presented granitoids that cover the time span from ordovician to early triassic constitute the main outcrops of the western sector of the yaminue block the southern yaminue metaigneous complex comprises highly deformed ordovician and permian granitoids crosscut by undeformed leucogranite dikes u pb shrimp zircon age of 254 2 ma mica separates from highly deformed granitoids from the southern sector yielded an ar ar muscovite age of 182 3 ma and a k ar biotite age of 186 2 ma moderately to highly deformed permian to early triassic granitoids made up the northern yaminue complex the late permian to early triassic u pb shrimp zircon age of 252 6 ma cabeza de vaca granite of the yaminue block yielded jurassic mica k ar cooling ages 198 2 191 1 and 190 2 ma at the boundary between the yaminue and nahuel niyeu blocks k ar muscovite ages of 188 3 and 193 5 ma were calculated for the flores granite whereas the early permian navarrete granodiorite located in the nahuel niyeu block yielded a k ar biotite age of 274 4 ma the jurassic thermal history is not regionally uniform in the supracrustal exposures of the nahuel niyeu block the early permian granitoids of its western sector as well as other permian plutons and ordovician leucogranites located further east show no evidence of cooling age reset since mica ages suggest cooling in the wake of crystallization of these intrusive rocks in contrast deeper crustal levels are inferred for permian early triassic granitoids in the yaminue block since cooling ages for these rocks are of jurassic age 198 182 ma jurassic resetting is contemporaneous with the massive lower jurassic flores granite and the marifil and chon aike volcanic provinces this intraplate deformational pulse that affected northeastern patagonia during the early jurassic sinemurian pliensbachian was responsible for the partial re exhumation of the mid crustal paleozoic basement along reactivated discrete ne sw to ene wsw lineaments and the resetting of isotopic systems these new thermochronological data indicate that early permian magmatic rocks of the nahuel niyeu block were below 300 c for ca 20 ma prior to the onset of the main magmatic episode of the late permian to triassic igneous and metaigneous rocks of the yaminue block

compositional variability of terrestrial mantle apatites thermodynamic modeling of apatite volatile contents and the halogen and water budgets of planetary mantles abstract apatites in ultramafic xenoliths from hawaii kamchatka nunivak island lunar crater volcanic field and the navajo volcanic field have variable volatile f cl oh compositions that correlate with their petrogenesis apatites in metasomatized lherzolite harzburgite xenoliths are relatively cl rich whereas apatites in igneous pyroxenite and amphibolite xenoliths are relatively f rich our results support the generalization of o reilly and griffin 2000 that metasomatic apatites tend to be cl rich and magmatic apatites tend to be f rich mantle metasomatism may largely be the consequence of devolatilization of cl rich fluids from subducted lithosphere however the occurrence of metasomatic xenoliths far removed from subduction zones e g bullenmerri as well as the geochemistry of cl in some plume basalts and diamonds indicates that not all metasomatism is subduction triggered thermodynamic modeling of the influence on apatite compositions of variable f cl h2o and p abundances as well as temperature is consistent with the idea that terrestrial mantle fluids are h2o rich and that halogen enrichment in terrestrial apatites need not represent large absolute halogen abundances in the fluids the models indicate that the occurrence of volatile poor calcium phosphate merrillite whitlockite in the martian and terrestrial mantles is facilitated by halogen and phosphorus rich and water poor environments the rarity of this assemblage in the terrestrial mantle compared to mars is consistent with the relatively wet and halogen and phosphorus poor nature of the terrestrial mantle compared to that of mars

a review of the relationships between granitoid types their origins and their geodynamic environments abstract granitoids are divided into several types according to their mineral assemblages their field and petrographical features and their chemical and isotopic characteristics this typology complements most of the recent classifications because it is not based solely on chemical and isotopic criteria but also on the field petrographical and mineralogical criteria it thus has the advantage of distinguishing the various granitoid types in the field in most cases the proposed classification shares many similarities with the twenty most used genetic classifications of granitoids both types of peraluminous granitoids are of crustal origin the tholeiitic alkaline and peralkaline granitoids are of mantle origin and both types of calc alkaline granitoids are of mixed origin and involve both crustal and mantle materials each granitoid type is generated and emplaced in a very specific tectonic setting each stage of the wilson cycle is characterised by typical associations of granitoids well typed and precisely dated granitoids can then complement structural approaches and indicate on the geodynamic environment with reference to some case studies the use of granitoids as tracers of the geodynamic evolution is also proposed and discussed

partition coefficients of hf zr and ree between zircon apatite and liquid concentration ratios of hf zr and ree between zircon apatite and liquid were determined for three igneous compositions two andesites and a diorite the concentration ratios of these elements between zircon and corresponding liquid can approximate the partition coefficient although the concentration ratios between apatite and andesite groundmass can be considered as partition coefficients those for the apatite in the diorite may deviate from the partition coefficients the hree partition coefficients between zircon and liquid are very large 100 for er to 500 for lu and the hf partition coefficient is even larger the ree partition coefficients between apatite and liquid are convex upward and large d 10 100 whereas the hf and zr partition coefficients are less than 1 the large differences between partition coefficients of lu and hf for zircon liquid and for apatite liquid are confirmed these partition coefficients are useful for petrogenetic models involving zircon and apatite

evidence in archaean alkali feldspar megacrysts for high temperature interaction with mantle fluids growth and regrowth textures trace element and oxygen isotope compositions and water content or species have been studied in alkali feldspars from the late archaean closepet igneous bodies feldspar crystals grew from mixed magmas that are characterized by a high degree of homogenization the 3d depiction of trace element distribution indicates that the crystallization process was followed by interaction with fluids the magmatic system involved in feldspar formation shows non linear dynamics the interaction with fluids is also deterministic but in contrast to magmatic crystallization it shows an increasing persistency in element behaviour the degree of persistency of the element activities in both processes has been calculated using the hurst exponent the recrystallization regrowth process induced by fluids proceeded along crystal fractures and cleavages causing selective enrichment in large ion lithophile elements light rare earth elements pb y and in various water species it did not change the feldspar oxygen isotope signature in turn the incorporation of hydrogen species into feldspar domains reduced al o al defect densities in the structure decreasing their luminescence water speciation shows persistent behaviour during heating the process being reversible at least up to 600 c carbonate crystals with a mantle isotope signature are associated with the re equilibrated feldspar domains the feldspar compositions the abundance of water species in them and the refractory nature of the residuum after heating the unchanged oxygen isotopes and the mantle signature of co precipitated carbonates testify that the observed recrystallization has taken place at temperatures above 600 c with h 2 o co 2 fertile mantle derived fluids the paper draws special attention to some methodological aspects of the problem the multi method approach used here major element trace element and isotope geochemistry infra red cathodoluminescence 3d depiction of geochemical data and fractal statistics may help to recognize and separate the various processes throughout the alteration history of the pluton

time evolution of chemical exchanges during mixing of rhyolitic and basaltic melts we present the first set of chaotic mixing experiments performed using natural basaltic and rhyolitic melts the mixing process is triggered by a recently developed apparatus that generates chaotic streamlines in the melts mimicking the development of magma mixing in nature the study of the interplay of physical dynamics and chemical exchanges between melts is carried out performing time series mixing experiments under controlled chaotic dynamic conditions the variation of major and trace elements is studied in detail by electron microprobe and laser ablation icp ms the mobility of each element during mixing is estimated by calculating the decrease in the concentration variance in time both major and trace element variances decay exponentially with the value of exponent of the exponential function quantifying the element mobility our results confirm and quantify how different chemical elements homogenize in the melt at differing rates the differential mobility of elements in the mixing system is considered to be responsible for the highly variable degree of correlation linear nonlinear or scattered of chemical elements in many published inter elemental plots elements with similar mobility tend to be linearly correlated whereas as the difference in mobility increases the plots become progressively more nonlinear and or scattered the results from this study indicate that the decay of concentration variance is in fact a robust tool for obtaining new insights into chemical exchanges during mixing of silicate melts concentration variance is in a single measure an expression of the influence of all possible factors e g viscosity composition and fluid dynamic regime controlling the mobility of chemical elements and thus can be an additional petrologic tool to address the great complexity characterizing magma mixing processes

interaction of typhoons with the taiwan orography part i upstream track deflections abstract a combined observational and numerical modeling approach is used to study the upstream track deflections of westward moving tropical cyclones approaching the mountainous terrain of taiwan although the standard deviations are large the mean track deflections are larger and have a different orientation for storms approaching the southern end of the island from those approaching the northern end the deflections tend to be larger for weaker and slower moving storms two distinct regions of upstream track deflections that are detected in the observations are explored in a sensitivity study with a 45 km horizontal resolution and 16 layer numerical model as the outer circulation of the tropical cyclone begins to interact with the mountain barrier the zonal decelerations and southward track deflections are explained by an enhanced blocking and deflection of the environmental flow advecting the cyclone the larger effect for southern approaching storms compared to northern storms is because the stron

evolution of magma mixing in an alkaline suite the grande cascade sequence monts dore french massif central geochemical modelling abstract trachyandesitic lavas from an alkaline suite grande cascade sequence monts dore french massif central have been investigated for evidence of mechanical magma mixing a wide variety of textures are present in the sequence as pillow like enclaves bandings and emulsified facies the grande cascade flows and pyroclasts range from basalt to trachyte 44 67 wt sio 2 pillow like enclaves intricate commingling and local diffusive mixing at the mafic felsic interface in emulsified types show that mafic inclusions were incorporated in their trachytic host as blobs of magma such inclusions were probably dispersed throughout the trachytic magma by mechanical mixing different stages of the evolution of a mechanical mixing process were recognized in relation with the stratigraphy and chronology of the products the most heterogeneous features enclaves bandings are restricted to the bottom of the sequence where basalt and trachyte coexist at the top texturally homogeneous trachyandesites occur relict phenocrysts are observed in both basaltic enclaves oligoclase fe rich clinopyroxene sanidine of the trachyte and trachytic hosts mg rich olivine mg rich clinopyroxene ca rich plagioclase of basalt the intermediate rocks basic trachyandesites contain xenocrysts of mg rich olivine clinopyroxenes oligoclase sanidine together with reversely zoned plagioclase and pyroxene phenocrysts this assemblage is presumed to result from the incorporation of xenocrysts related both to mafic and felsic endmembers all mineral assemblages are out of equilibrium reversed compositional zoning profiles in plagioclase and clinopyroxene crystals were produced by the mixing event we are able to identify the compositional characteristics of the components that were mixed a primary alkaline basalt mg olivine labrador mg clinopyroxene magnetite and a silicic trachyte oligoclase fe clinopyroxene sanidine are the endmembers of mixing observed chemical variations in major and trace elements can be modelled as pure binary mixtures between basaltic and trachytic endmembers using the best mixing line method provost and allegre 1979 the calculations emphasize that trachyandesites are the result of complete hybridization between basalt and trachyte the data on mesostasis show that melt mixing and not only crystal transfers has produced the intermediate lavas of the grande cascade sequence textural criteria petrography mineral chemistry and geochemical data major and trace elements support the magma mixing model

apatite liquid partition coefficients for the rare earth elements and strontium abstract sixteen sets of apatite liquid partition coefficients dap liq for the rare earth elements ree la sm dy lu and six values for sr were experimentally determined in natural systems ranging from basanite to granite the apatite melt glass assemblages were obtained from starting glasses artificially enriched in ree sr and fluorapatite components these were run under dry and hydrous conditions of 7 5 20 kbar and 950 1120 c in a solid media piston cylinder apparatus an sem equipped electron microprobe was used for subsequent measurement of ree and sr concentrations in coexisting apatites and quenched glasses the resulting partition coefficient patterns resemble previously determined apatite phenocryst groundmass concentration ratios in the following respects 1 the rare earth patterns are uniformly concave downward i e the middle ree are more compatible in apatite than the light and heavy ree 2 dreeap liq is much higher for silicic melts than for basic ones and 3 strontium and therefore eu2 is less concentrated by apatite than are the trivalent ree the effects of both temperature and melt composition on dreeap liq are systematic and pronounced at 950 c for example a change in melt sio2 content from 50 to 68 wt causes the average ree partition coefficient to increase from 7 to 30 a 130 c increase in temperature on the other hand results in a two fold decrease in dreeap liq partitioning of sr is insenstitive to changes in melt composition and temperature and neither the sr nor the ree partition coefficients appear to be affected by variations in pressure or h2o content of the melt the experimentally determined partition coefficients can be used not only in trace element modelling but also to distinguish apatite phenocrysts from xenocrysts in rocks reported apatite megacryst host basalt ree concentration ratios 12 for example are considerably higher than the equilibrium partition coefficients which suggest that in this particular case the apatite is actually xenocrystic a reversal experiment incorporated in our study yielded diffusion profiles of ree in apatite from which we extracted a ree ca interdiffusion coefficient of 2 4 10 14 cm2 s at 1120 c extrapolated downward to crustal temperatures this low value suggests that complete ree equilibrium between felsic partial melts and residual apatite is rarely established

magmatic structures in the krkonose jizera plutonic complex bohemian massif evidence for localized multiphase flow and small scale thermal mechanical instabilities in a granitic magma chamber abstract the present paper examines magmatic structures in the jizera and liberec granites of the krkonose jizera plutonic complex bohemian massif the magmatic structures are here interpreted to preserve direct field evidence for highly localized magma flow and other processes in crystal rich mushes and to capture the evolution of physical processes in an ancient granitic magma chamber we propose that after chamber wide mixing and hybridization as suggested by recent petrological studies laminar magma flow became highly localized to weaker channel like domains within the higher strength crystal framework mafic schlieren formed at flow rims and their formation presumably involved gravitational settling and velocity gradient flow sorting coupled with interstitial melt escape local thermal or compositional convection may have resulted in the formation of vertical schlieren tubes and ladder dikes whereas subhorizontal tubes or channels formed during flow driven by lateral gradients in magma pressure after the cessation or deceleration of channel flow gravity driven processes settling of crystals and enclaves gravitational differentiation development of downward dripping instabilities accompanied by compaction filter pressing and melt segregation dominated in the crystal mush within the flow channels subsequently magmatic folds developed in schlieren layers and the magma chamber recorded complex late magmatic strains at high magma crystallinities late stage magma pulsing into localized submagmatic cracks represents the latest events of magmatic history of the chamber prior to its final crystallization we emphasize that the most favorable environments for the formation and preservation of magmatic structures such as those hosted in the jizera and liberec granites are slowly cooling crystal rich mushes therefore where preserved in plutons these structures may lend strong support for a mush model of magmatic systems

diffusive fractionation of trace elements by chaotic mixing of magmas abstract recent research on magma mixing systems has shown that the mixing process is governed by chaotic dynamics and that this process is responsible for the generation of fractal structures that propagate within the magmatic mass from the meter to the micrometer length scale laser ablation icp ms trace element analyses have been performed on rock samples with evidence of chaotic mixing phenomena results indicate that trace elements with similar values of diffusion coefficient display good correlations in inter elemental plots whereas as the difference between diffusion coefficients increases the correlation is progressively lost in addition a large variability of ree patterns is observed with the remarkable feature of the presence of positive and negative eu anomalies occurring at short length scale of the order of few mm given the chaotic nature of magma mixing structures the mixing process has been simulated by coupling a chaotic advection and a chemical diffusion numerical scheme by considering several trace elements with variable diffusivities simulations indicate that such a model explains with good approximation the variable correlations among trace elements observed in natural samples in addition the same patterns of ree observed in natural samples including the occurrence of positive and negative eu anomalies at short length scale are observed indicating that a chaotic advection diffusion dynamic system is a suitable model to explain natural data results presented in this contribution indicate that at the micrometric length scale small volumes of magmas are strongly influenced by the coupled action of chemical diffusion and chaotic flow fields and hence they do not represent magmas de facto present in the magmatic system because their compositions may have experienced a diffusive fractionation process these results may have important petrogenetic implications for instance if such melts were trapped as melt inclusions they would provide misleading information about melt compositions it is suggested that the approach of studying the degree of correlation among trace elements may be a possible method to test if melt inclusion compositions commonly used as petrogenetic indicators display evidence of such a diffusive fractionation process

late variscan emplacement and genesis of the vieira do minho composite pluton central iberian zone constraints from u pb zircon geochronology ams data and sr nd o isotope geochemistry abstract in the central iberian zone synorogenic syn and late d3 the last deformation phase composite batholiths of biotite rich granitods with peraluminous character are well represented we report here u pb zircon and monazite ages geochemical sr nd o isotopic data and anisotropy of magnetic susceptibility ams studies for the late d3 vieira do minho pluton in northern portugal ams reveals the paramagnetic behaviour of these granites and the magnetic fabric enhances the major role of nw se regional anisotropies on controlling the ascent and emplacement of the magmas magnetic anisotropy and medium temperature microstructures also point out the evolution of regional tectonics during crystallization of the magma u pb zircon and monazite analyses yield consistent ages of 310 2 ma and 312 2 ma interpreted as emplacement age the vieira do minho pluton consists of two peraluminous monzogranites the vmg and the mrg both have similar end values vmg 5 2 to 5 7 mrg 4 98 to 5 96 but the vmg is slightly enriched in 87sr 86i 0 7087 0 7098 as well as in 18o in the range of 10 6 to 11 0 than the mrg with 87sr 86i 0 7064 0 7075 and 18o 9 9 10 5 these granites are associated with coeval scarce grabroic intrusions and or mafic microgranular enclaves which are not considered as mafic precursors of the associated granitic magmatism instead a lower metaigneous crustal source at different levels is proposed based on the available data set

magma mixing in the genesis of hercynian calc alkaline granitoids an integrated petrographic and geochemical study of the sazava intrusion central bohemian pluton czech republic the devonian early carboniferous 354 1 3 5 ma conventional zircon u pb age sazava intrusion biotite amphibole quartz diorite tonalite and granodiorite of the central bohemian pluton cbp associated with bodies of olivine pyroxene amphibole gabbro gabbrodiorite quartz diorite and rare hornblendite gives an opportunity for a comparative study of a rather shallow calc alkaline magma mixing zone at two levels separated by a vertical difference of approximately 1 km the deeper section p ibram displays the direct evidence for the existence of a long lived periodically tapped and replenished floored magma chamber masli the contacts between the subhorizontal sheet like basic bodies and the surrounding commonly cumulus rich sazava granitoid are arcuate and cut by a series of veins and ascending pipes shallow dipping swarms of strongly elongated and flow aligned mafic microgranular enclaves mme concordant with the contacts of the basic bodies are commonplace the higher level teletin section shows relatively independent basic intrusions some of them distinctly hybrid in character and mainly of quartz dioritic composition surrounded by relatively homogeneous nearly cumulus free sazava tonalite rich in texturally variable mme larger quartz microdiorite bodies and the mme both interpreted as hybrids contain varying proportions of highly heterogeneous plagioclase megacrysts with complex zoning particularly well shown by cathodoluminescence cl most often the megacrysts have cores of labradorite anorthite partly resorbed and overgrown by andesine rims but some are strongly brecciated and fragments have been annealed by rim growth also characteristic are long prisms of apatite oikocrysts of quartz and k feldspar and zoned amphibole the latter has brown pargasite and magnesiohastingsite cores resorbed and overgrown by magnesiohornblende compositionally similar to the amphibole in the sazava tonalite the brown cores are probably relics of a higher p t stage with temperature exceeding 900 c plots of major element analyses of the teletin quartz microdiorite and the mme fall close to the line joining the compositions of the evolved sazava granodiorite tonalite and the associated gabbros the estimated minimal proportions of the acidic end member range from ca 15 to 20 for the quartz microdiorite and ca 40 to 60 for the enclaves field relationships macroscopic and mineralogical features and whole rock geochemistry are consistent with a hybrid origin of the quartz microdiorite masses and enclaves unzoned calcic plagioclase cores are interpreted as having crystallized from a basic magma prior to its injection into a high level acidic magma chamber the sudden decrease in ca activity and introduction of water due to magma mixing with tonalitic melt led to their resorption and brecciation quartz ocelli that are abundant locally in some basic bodies are most likely xenocrysts introduced from the felsic magma in the basic melt they were resorbed and became a substrate for heterogeneous nucleation of the amphibole or pyroxene coronas strong undercooling of the basic magma resulted in the growth of long prismatic apatite together with dendritic boxy cellular plagioclase both types of plagioclase cores were subsequently overgrown by more sodic mantles at the same time small unzoned plagioclase crystals nucleated in the groundmass following thermal re adjustment crystallization of the hybrid magma ended with considerably slower growth of quartz and k feldspar oikocrysts

enhancement of magma mixing efficiency by chaotic dynamics an experimental study magma mixing is common in the earth understanding the dynamics of the mixing process is necessary for dealing with the likely consequences of mixing events in the petrogenesis of igneous rocks and the physics of volcanic eruptive triggers here a new apparatus has been developed in order to perform chaotic mixing experiments in systems of melts with high viscosity contrast the apparatus consists of an outer and an inner cylinder which can be independently rotated at finite strains to generate chaotic streamlines the two cylinder axes are offset experiments have been performed for ca 2 h at 1 400 c under laminar fluid dynamic conditions re 10 7 two end member silicate melt compositions were synthesized 1 a peralkaline haplogranite and 2 a haplobasalt the viscosity ratio between these two melts was of the order of 103 optical analysis of post experimental samples reveals a complex pattern of mingled filaments forming a scale invariant i e fractal distribution down to the m scale as commonly observed in natural samples this is due to the development in space and time of stretching and folding of the two melts chemical analysis shows strong non linear correlations in inter elemental plots the original end member compositions have nearly entirely disappeared from the filaments the generation of thin layers of widely compositionally contrasting interfaces strongly enhances chemical diffusion producing a remarkable modulation of compositional fields over a short length scale notably diffusive fractionation generates highly heterogeneous pockets of melt in which depletion or enrichment of chemical elements occur depending on their potential to spread via chemical diffusion within the magma mixing system results presented in this work offer new insights into the complexity of processes expected to be operating during magma mixing and may have important petrological implications in particular 1 it is shown that in contrast with current thinking rheologically contrasting magmas can mix i e with large proportions of felsic magmas and high viscosity ratios thus extending significantly the spectrum of geological conditions under which magma mixing processes can occur efficiently 2 the mixing process cannot be modeled using the classical linear two end member mixing model and 3 the chemical compositions on short length scales represent snapshots within the process of mixing and therefore may not reflect the final composition of the magmatic system this study implies that microanalysis on short length scales may provide misleading information on the parental composition of magmas

evaluation of magma mixing and fractional crystallization using whole rock chemical analyses polytopic vector analyses 1 magma mixing and crystal fractionation are fundamental processes that lead to the diversity of magma compositions but rarely are all of the major and trace element data on whole rocks used simultaneously in evaluating proposed models polytopic vector analysis pva is an oblique factor analysis procedure designed specifically to evaluate mixing or unmixing fractional crystallization in geologic systems using all of the analytes major and trace elements simultaneously it differs from other techniques in that it not only determines the number of end members and their compositions but also partitions the relative proportions of the end members into each sample in the data array these samples expressed as proportions of end members can be used as input in other multivariate analyses the purpose of this paper is to use pva to evaluate some examples of magma mixing and fractional crystallization and use these examples as templates for more complicated systems in order to show both the strengths and the weaknesses of the approach five well constrained examples illustrate how pva can discriminate between these two processes and provide additional petrogenetic information using pva mixing between magma types can be easily distinguished from crystal fractionation with fractional crystallization the end members generated by pva are the initial and final liquids and the compositions where new phases join the crystallizing assemblage

mineral textures and zoning as evidence for open system processes investigations of mineral textures and zoning as evidence for open system processes during magmatic evolution have always been a centerpiece of petrological studies and have provided some of the best evidence for magma mixing and crustal contamination for many decades e g milch 1905 kuno 1936 eichelberger 1975 sato 1975 anderson 1976 in fact evidence from mineral studies was instrumental in the acceptance of magma mixing as important petrological process ever since it was initially proposed by bunsen 1851 in recent years mineral studies are invigorated by the development of high precision high resolution analytical instruments and techniques through which textural information and compositional data are combined e g jerram and davidson 2007 as minerals respond texturally and compositionally to changing magmatic environments they preserve in their crystal growth stratigraphy a wealth of information regarding their past history of magmatic processes and compositions cf ginibre et al 2007 on the other hand magmatic liquids melts are snapshots of current magmatic states and provide less direct evidence of the processes responsible for their evolution in addition liquids may crystallize thereby destroying the direct evidence they provide with an appropriate set of observations and measurements we can correlate textures with mineral compositions and thus produce a richer composite picture of magmatic evolution than compositional data of minerals alone this contribution reviews the zoning and textures of minerals frequently encountered in volcanic rocks many of which apply equally to plutonic rocks and the interpretations ascribed to these features in terms of open system magmatic processes first i will address the analytical tools that are used to acquire textural and compositional data followed by a brief review of open system processes and a summary of the relevant textures from that point on i will address some mineral specific aspects followed by a discussion

trace element mobility during magma mixing preliminary experimental results abstract magma mixing tests have been performed experimentally in a taylor couette like experimental setting the variation of trace element concentrations along transects crossing the resultant melt column has been measured results indicate a strongly variable mobility of the different trace elements in the same mixing system such a different behaviour of trace elements tends to be enhanced as the mixing time increases leading to the production of highly heterogeneous volumes of melts in which depletion and enrichment of trace elements occurred depending on their potential of spreading across the magma mixing system the results presented here offer new insights into the complexity of processes expected to be operating during mixing of magmas it is demonstrated that on short mixing times also the trace elements may become highly non correlated this is due to the development of chaotic advection diffusion processes in the system these results indicate that the onset of diffusive fractionation processes may strongly influence the patterns of data on inter elemental diagrams depending on the relative mobility of the different elements

trace element partitioning between apatite and silicate melts we present new experimental apatite melt trace element partition coefficients for a large number of trace elements cs rb ba la ce pr sm gd lu y sr zr hf nb ta u pb and th the experiments were conducted at pressures of 1 0 gpa and temperatures of 1250 c the rare earth elements la ce pr sm gd and lu y and sr are compatible in apatite whereas the larger lithophile elements cs rb and ba are strongly incompatible other trace elements such as u th and pb have partition coefficients close to unity

feldspar megacrysts from the santa angelica composite pluton formation transformation path revealed by combined cl raman and la icp ms data abstract the studied feldspar megacrysts from the santa angelica hybrid rock unit feature complex growth morphologies and geochemical compositions early crystallization formed zoned k na alkali feldspar and unzoned oligoclase andesine the chemical composition of the zoned alkali feldspar reflects crystallization in contact with different magma batches and the chemical composition of the plagioclase indicates growth from a homogeneous magma further feldspar development produced mineral chemistry and growth morphology patterns in both alkali feldspar and plagioclase that indicate a multi stage process caused by the combination of chaotic mixing and replenishment alkali feldspar and plagioclase megacrysts show dissolution and regrowth textures their compositional fields are not separated different crystallized and recrystallized domains pass smoothly from one to another a multiple reequilibration process limited the ordering of the feldspar domain structure a younger generation of feldspar strongly enriched in k and na grew over the dissolved margins of the alkali feldspar and plagioclase megacrysts filling all embayments some domains of the alkali feldspar megacrysts recrystallized resulting in a k and ba rich composition the trace element patterns of these domains define relatively consistent trends which may indicate a new stage of equilibrium in turn the trace element patterns of previously crystallized and recrystallized domains are irregular pointing to blurring of the original compositional relationship some voids in the megacrysts formed due to dissolution are cemented with quartz the sequential early to late crystallization recrystallization and alteration processes are clearly revealed by polytopic vector analysis pva this analysis shows the changes in the alkali feldspar and plagioclase compositions in two different directions an initial shift from megacryst crystallization environment towards alkali rich magma and a second shift towards silica rich magma the recognition of the whole sequence of the processes is possible due to the preserved relics of each phase in different feldspar domains

caught in the act implications for the increasing abundance of mafic enclaves during the recent eruptive episodes of the soufriere hills volcano montserrat 1 an exceptional opportunity to sample several large blocks sourced from the same region of the growing soufriere hills lava dome has documented a significant increase in the presence of mafic enclaves in the host andesite during the course of a long lived eruptive episode with several phases in 1997 phase i mafic inclusions comprised 1 volume percent of erupted material in 2007 phase iii deposits their volumetric abundance increased to 5 7 percent a broader range of geochemically distinctive types occurs amongst the 2007 enclaves crystal poor enclaves generally have the least evolved basaltic compositions porphyritic enclaves represent compositions intermediate between basaltic and andesitic compositions the absence of porphyritic enclaves prior to phase iii magmatism at soufriere hills volcano suggests that a mixing event occurred during the course of the current eruptive episode providing direct evidence consistent with geophysical observations that the system is continuously re invigorated from depth

the space and time complexity of chaotic mixing of silicate melts implications for igneous petrology abstract we present new experimental results on the study of the space and time modulation of compositional fields during chaotic mixing between mafic and felsic silicate melts the experimental strategy was planned using numerical simulations performed using the experimental geometry these mixing experiments were performed using a recently developed experimental apparatus which is capable of mixing high viscosity silicate melts at high temperatures and under precisely controlled conditions of fluid dynamics and strain the compositional variability produced by the mixing process was investigated both along linear analytical transects and on high resolution 2d x ray maps covering the mixing patterns our results indicate that chaotic flow fields represent very powerful dynamics to blend silicate melts even under laminar fluid dynamic conditions reynolds number ca 10 7 and for dissimilar melts with high viscosity ratios on the order of 103 the repetition of stretching and folding processes between the two melts induced a strong increase of contact interfaces thus favoring efficient chemical exchanges as a result the initial mafic composition is no longer detectable in the mixing system after ca 2 h i e the duration of the experiment a further important result is the observation of highly non linear patterns in inter elemental plots produced by the onset of diffusive fractionation processes this is contrary to common thinking that magma mixing should always produce linear trends between pairs of chemical elements a new measure the concentration variance is proposed to quantify chemical element mobility during the mixing process this measure is statistically robust and can be quantitatively used to measure chemical element mobility independently of the geometry in which the compositional variation i e transects areas etc is embedded or the local strain history of the mingling our results highlight concentration variance as a robust probe of the as yet poorly understood processes involved in the common petrological process of magma mixing

chaotic three dimensional distribution of ba rb and sr in feldspar megacrysts grown in an open magmatic system as has been demonstrated in recent years the heterogeneities of coeval magmas can be more successfully revealed by zoned megacrysts rather than by analysis of the whole rocks hosting them here the geochemical heterogeneities of feldspar megacrysts from the karkonosze granite poland are investigated by la icp ms the crystals are the product of migration and growth in regions of poorly mixed magmas 3d modeling of the ba sr and rb distributions emphasizes the importance of micro domain growth morphologies two models of element behavior a relative concentration model and a composition gradient model provide a potentially effective tool for tracking the mixing process on a microscale measured concentrations of elements of different mobilities do not agree with what might be expected from the mixing of two end member magmas if mixing was the only process occurring linear correlations between the concentrations of any two elements should be observed this however is not the case for combinations of any two of the three elements modeling reveals differing non linear correlations between concentrations the megacryst heterogeneities provide an insight into how mixing magmas are chaotically advected to growing crystals and the degree of inter magma element exchange between the magmas

polytopic vector analysis pva modelling of whole rock and apatite chemistry from the karkonosze composite pluton poland czech republic abstract this study presents a novel approach for analysing the magma evolution path in composite plutons applying the so termed polytopic vector analysis pva to whole rock and apatite chemistry as an example of a multiphase magmatic body the karkonosze granitoid pluton was chosen which formed by a combination of magma mixing and fractional crystallization of two distinct melts granitic crust derived and lamprophyric mantle derived the goal was to model end member magma compositions recorded by apatite and to estimate to what extent these end members interacted with each other although using single minerals as proxies to magma compositions is tricky the studied apatite well reflects the compositional trends within the magma e g decreasing lree y ratios varying halogen content increasing mn and na concentrations the results of pva simulations for whole rock geochemistry demonstrate a model similar to that constrained from previous studies apart from the main trend of mixing between a felsic 80 wt sio 2 and a mafic 53 wt sio 2 end member em an additional process has been recognized representing most probably the continuous evolution of the mafic end member responsible for the compositional diversity of some rocks one felsic ree poor mn f rich and one mafic cl sr si ree rich apatite end members were recognized whereas the third one represents most probably a fluid component enriched in si y ce and nd present at all magmatic stages however most prominent during the late stage the widest range of em proportions and the highest contribution of the mafic em are displayed by apatites from the early stage during the middle and late stages the apatites present a narrow range of em proportions with almost all apatites bearing a felsic signature this pattern reflects the progressive homogenization of the system although the pva method applied to mineral chemistry poses some limitations it may provide a more detailed image of the combination of differentiation processes and magma sources involved in the formation of a complex composite pluton

the geochemistry of phosphorus in different granite suites of the western carpathians slovakia the role of apatite and p bearing feldspar the geochemical behaviour of phosphorus in granites coupled with compositional variations in apatite discriminate the different genetic suites of variscan granitic rocks in the west carpathian orogenic belt meso variscan granites mostly of stype affinity show a good correlation between sio2 and p2o5 with decreasing amounts of p in the poorly and moderated fractionated granites and increasing phosphorus in the most evolved and late differentiation products the aluminium saturation index asi correlates negatively with bulk p contents in i type granites and positively with p in s type granites the phosphorus content of alkali feldspar mainly kfs is usually very low typically 0 05 wt p2o5 or not detected in the slightly differentiated granites in the latevariscan i s type granitoids phosphorus is hosted mainly in the early magmatic apatite but is present also in the late k feldspar up to 0 15 wt of p2o5 that formed from the residual melts in the postorogenic s type granites the bulk of the phosphorus occurs in alkali feldspar f0 3 wt p2o5 with a minor proportion present in primary early magmatic apatite clusters of small secondary apatite grains with a distinctive composition are distributed in alkali feldspar grains of the post orogenic s type granites this apatite has formed post magmatically from p released from p rich alkali feldspar during decreasing temperature by reaction with a fluid rich in volatiles including f and b and alkali and alkali earth metals a type granites have the lowest bulk phosphorus contents consequently phosphate minerals are relatively rare in this granite type and the alkali feldspar has negligible p2o5 contents except for sr the minor element contents in apatite partly correlate with the bulk composition of their host rocks and partly reflect some thermodynamic properties of melt the mn contents of apatite increase with the peraluminous character of the melt and with decreasing fo2 and so apatite from the s type granites has significantly higher mn contents than apatite from the i type granites apatite from a type granites is enriched in fe and hree reflecting the higher bulk fe and hree content of this granite type apatite from specialized s type granites is enriched in yand hree in general the cl and s content of apatite is higher in the basic members of the i type affinity granitic rocks d 2004 elsevier b v all rights reserved

identifying relationships among silicic magma batches by polytopic vector analysis a study of the topopah spring and pah canyon ash flow sheets of the southwest nevada volcanic field abstract the chemically and mineralogically zoned topopah spring silicic ash flow sheet 12 8 ma 1200 km3 in the southwest nevada volcanic field swnvf contains two pumice fragment populations a lower silica ls and a high silica rhyolite hsr composition recent interpretations are that these magmas represented by the pumice fragments were not related by afc processes within a single magma chamber the emplacement of the pah canyon ash flow sheet followed the topopah spring ash flow sheet eruption this smaller volume 35 km3 ash flow sheet contains pumice fragments that were previously interpreted as a hybrid magma formed by mixing of residual topopah spring ls and hsr magmas pumice fragments from these ash flow sheets were analyzed by polytopic vector analysis pva a multivariate statistical program that describes each sample in a dataset in terms of some proportion of each end member generated by the program therefore each sample or pumice fragment is uniquely described by some amount of each of the end members so that graphical analysis of the dataset allows the immediate recognition of separate magma batches as pumice fragment samples cluster in discrete groups and show different variations in end member proportions recognition of hybrid magmas is also immediately apparent as pumice fragments representing mixed magmas must plot between the parent magmas pumice fragment groups our results confirm the existence of independently generated magmas involved in the formation of the topopah spring ash flow however pva of pah canyon pumice fragments reveals that pah canyon cannot be described solely as a hybrid magma derived from topopah spring ls and hsr magmas furthermore pah canyon and the topopah spring hsr pumice fragments have identical trends in the variation of end member proportions that most likely represent crystal fractionation or accumulation in both magmas that was previously undetected this pattern is inconsistent with simple mixing between the ts ls and ts hsr magmas rather it is consistent with magma mixing followed by fractional crystallization

chaotic advection fractals and diffusion during mixing of magmas evidence from lava flows structures of magma mixing from three different lava flows have been analyzed and the degree of mingling has been quantified by measuring the contact perimeter between magmas and the fractal dimension of structures in each lava flow the values of these parameters suggest that the magma mixing structures were produced by chaotic dynamics induced by stretching and folding processes between the interacting magmas the mingling of magmas has been simulated using a chaotic dynamical system consisting of repeated stretching and folding processes the simulation shows the same patterns of variation of contact perimeter and fractal dimension as those observed in natural structures and indicates that magma interaction processes acted with different intensities in the three lava flows in response to different magmatic interaction regimes since physical dispersion of one magma inside another through stretching and folding processes and chemical exchanges are closely related we performed coupled numerical simulations of chaotic advection and chemical diffusion the results show a good agreement between the computed and natural structures in particular the occurrence in the same system of well and poorly mixed regions it is shown that magma interaction processes are able to generate magmatic masses having wide spatial heterogenity at many length scales this occurrence can account for the presence of magmatic enclaves inside host rocks showing a variable degree of hybridization in both plutonic and volcanic environments

k feldspar phenocrysts in microgranular magmatic enclaves a cathodoluminescence and geochemical study of crystal growth as a marker of magma mingling dynamics abstract the crystallization history of zoned k feldspar phenocrysts in microgranular magmatic enclaves in the karkonosze granite sw poland reveals that the crystals grew in stirred coeval magmas of contrasting compositions the growth mechanism and crystal compositions are investigated using cathodoluminescence and profiling by electron microprobe and laser ablation icp ms these methods provide insight into the crystallization process and the varying compositions of the host melt the phenocrysts show two types of growth patterns with or without resorption interfaces the trace element distribution heterogeneous across different zones and within single phenocryst zones reflects a dynamic process of crystal growth from compositionally heterogeneous magma hybridization is also reflected in the density of structural al o al defects features that relate to coupled ba al incorporation into the crystal structure differences in structural defect densities and crystal composition trace the degree of hybridization in the granitic magma during the growth of the k feldspar phenocrysts

multistage magma emplacement and progressive strain accumulation in the shallow level krkonose jizera plutonic complex bohemian massif 1 field relationships combined with new u pb zircon geochronology suggest that the shallow level krkonose jizera plutonic complex northern bohemian massif was assembled successively from bottom to top starting with emplacement of the separately evolved s type tanvald granite 317 3 2 1 ma followed by at least two voluminous batches of the i type porphyritic liberec 319 5 2 3 ma and jizera 320 1 3 0 ma and 319 3 3 7 ma granites the intrusive sequence was completed by uppermost minor intrusions of the equigranular harrachov 315 0 2 7 ma and krkonose granites the i type granites exhibit an unusually complex pattern of superposed feldspar phenocryst and magnetic fabrics as revealed from the anisotropy of magnetic susceptibility ams the outer liberec granite preserves margin parallel foliations and lineations interpreted to record emplacement related strain captured by cooling from the pluton floor and walls in contrast the inner jizera harrachov and krkonose granites were overprinted by synmagmatic strain resulting from dextral movements along regional strike slip faults cutting the opposite ends of the plutonic complex late stage felsic dikes in the liberec and jizera granites reorient from horizontal to vertical lineation perpendicular attitude in response to changing the least principal stress direction whereas mafic schlieren do not do so representing only randomly oriented small scale thermal mechanical instabilities in the phenocryst framework in general this case example challenges the common approach of inferring pluton wide magma flow from interpolated foliation lineation and schlieren patterns more likely magmatic fabrics in large plutons record complex temporal succession of superposed strains resulting from diverse processes at multiple scales