silurian turbidite provenance on the northern avalonian margin the windermere supergroup of nw england was deposited in a foreland basin on the northern margin of eastern avalonia and preserves an almost complete ashgill to poidoli sequence it was ideally positioned to record provenance changes associated with the closure of the iapetus ocean petrographic geochemical and nd isotopic parameters show distinct and concordant temporal trends the late ashgill to early llandovery is characterized by progressive hemipelagic dilution of material derived from the underlying borrowdale volcanic group from the llandovery onward petrographic and geochemical data indicate supply from a recycled orogen source input from the scandian orogen may be inferred no conclusive evidence is recorded of laurentian input into the basin by the late wenlock a unified sedimentary system probably spanned the iapetus ocean an abrupt reversal in provenance trends towards the end of the ludlow records basin inversion the occlusion of the iapetus seaway and concomitant cannibalization of older foreland basin sediments provenance data derived from upper wenlock to poidoli sediments aid the characterization of marine foreland basins

turbidite provenance in the lower palaeozoic manx group isle of man implications for the tectonic setting of eastern avalonia the provenance of turbidites from the predominantly arenig aged manx group has been constrained using petrographical and geochemical techniques petrographical analysis of sandstones reveals that mono and poly crystalline quartz grains of cratonic origin are dominant major trace and rare earth element concentrations in both sandstones and mudstones complement the petrographical data indicating that the source of the sediments consisted of quartzose basement and mature sedimentary rocks there is little evidence of a juvenile volcanic input but a minor palaeovolcanic component of active continental margin affinity is present there are indications of a more immature character in the oldest units but on the whole geochemical data from the manx group suggest an overall passive margin setting these results suggest that eastern avalonia was attached to gondwana during deposition of the manx group and that iapetus oceanic crust did not subduct beneath the region before the end of the arenig

quartz arenites of the cambro ordovician kamouraska formation quebec appalachians canada ii eolian sands in deep sea sedimentary gravity flow deposits the kamouraska formation is a quartz arenitic unit of latest cambrian earliest ordovician age in the quebec appalachians that was deposited by hyperconcentrated to concentrated density flows in a meandering submarine canyon on the continental slope bordering the iapetus ocean as outlined in a companion paper detailed petrographic study of the quartz arenites of the kamouraska formation combined with scanning electron microscopy of grain surface textures suggests that the quartz sands are of eolian origin having been derived from an inland desert or less likely a barrier beach dune system transport of the mature quartz arenitic sand onto the shelf and deposition into the deep sea was not accompanied by substantial mixing with material from other sources thus preserving the inherited eolian characteristics a modern analogue for the eolian interpretation of the deep sea quartz arenite beds is as follows thick late pleistocene eolian sand beds on a modern abyssal plain in the east atlantic referred

sandstone petrography and geochemistry of late proterozoic sediments of the armorican massif france a key to basin development during the cadomian orogeny abstract brioverian late proterozoic sediments of the armorican massif in northwest france are contained within isolated basins whose development is linked to cadomian orogenesis these basins were formed between c 650 and 530 ma ago mainly by gravitational flow processes petrographical study and geochemical analysis of major and trace elements show that the sandstone formations of north brittany are characterized by great immaturity 10 20 feldspar 10 20 lithic fragments and high concentrations of na2o ba sr v and cr the formations from western and central brittany as well as the southern part of normandy are compositionally more mature 1 petrographical and geochemical data for north brittany formations yield plots which suggest a mixed source region composed of a continental active margin island arc and ancient basement material sedimentation of the brioverian group was influenced by a distensive tectonic regime towards the south sedimentary formations are characterized by continental source areas and were laid down in a passive tectonic environment however ree distribution patterns for sediments of this southern domain preserve evidence for the contribution of magmatic arc material such formations could have been deposited in a marginal basin

provenance of triassic cretaceous sandstones in the antarctic peninsula implications for terrane models during gondwana breakup abstract the antarctic peninsula is the largest of twelve micro continental fragments between southern south america east antarctica and new zealand their original positions and movement history following gondwana breakup are poorly constrained recent work on the antarctic peninsula fore arc arc back arc suggests it consists of two suspect terranes that originated elsewhere and collided with the pacific margin of gondwana in the cretaceous this study reviews provenance models for three laterally extensive kilometers thick sedimentary units in the antarctic peninsula using previous studies and new sandstone detrital modes and chemistry 1 the trinity peninsula group accretionary complex triassic was possibly derived from a glaciated continental margin and may consist of several accreted tracts the deformed quartzose view point and legoupil formations were eroded from a deeply eroded stable continental margin containing an old arc and mature quartzose sandstones with provenance ages suggesting sources in north patagonia and local antarctic peninsula basement the weakly deformed and more feldspathic hope bay formation was derived from an eroded arc possibly the early permian arc of the north patagonian massif 2 the lemay group accretionary complex middle triassic middle cretaceous is dominated by arkoses derived from an eroded continental margin of carboniferous and permian age possibly in the marie byrd land sector with several belts of volcanilithic sandstones representing episodes of arc magmatism the youngest part of the lemay group contains abundant metamorphic detritus derived from basement uplifted during mid cretaceous terrane docking 3 the latady formation in the southern antarctic peninsula has a completely different petrology comprising mature sublitharenites 190 ma of gondwanan provenance deposited in restricted rift basins younger volcanic litharenites 180 ma are dominated by ree enriched low eu eu rhyolitic material eroded from silicic calderas associated with gondwana breakup abundant dacitic to andesitic detritus in the youngest lf 160 145 ma was derived from a contemporaneous arc possibly on the thurston island block as the latady evolved into a back arc basin

petrographic classification of sand and sandstone abstract petrographic classifications of sand and sandstone proposed more than half a century ago are still in use although they were formulated at a time when depositional and post depositional sedimentary processes were poorly understood and before the relationships between tectonics and sedimentation could be interpreted in modern plate tectonic terms as a consequence too many scientific articles and technical reports are still encumbered with obsolete concepts graphical tools and ambiguous terminology that make sediment descriptions awkward and misleading a renovation that treasures the legacy of the pioneers is required the descriptive petrographic classification of sand and sandstone proposed in this paper is based on the quasi universally used gazzi dickinson point counting method and simply translates into words ternary compositions of quartz feldspar and lithic fragments without introducing any new names the classic qfl plot is subdivided into 15 fields labelled by adjectives introduced long ago by k a w crook and endorsed by w r dickinson and more recently by g j weltje which reflect relative abundances of the three main framework components provided they exceed 10 qfl according to standard use the less abundant component goes first the more abundant last e g litho feldspatho quartzose composition translates into q f l 10 qfl for lithic rich sand and sandstone information on the prevailing rock fragment type can be added by an additional free adjective e g metamorphiclastic carbonaticlastic as proposed long ago by r v ingersoll for lithic poor feldspatho quartzose and quartzose sand and sandstone further formal subdivisions are proposed based on the q f ratio thus reaching a total of 18 compositional fields overall modern sand known to be derived from different source rocks and found in major world s rivers deserts and deep sea fans fits in the pigeonholes defined by the relative abundance of quartz feldspar and lithic fragments the aim of this classification is to restore directness in sandstone petrology and to avoid ambiguities generated in the past by making reference to badly defined archetypes such as greywacke or arkose thus confusing petrographic composition with subjective considerations about plate tectonic setting texture hydraulic behaviour mechanical durability or chemical durability in the illusion that a classification could be genetic at the same time as descriptive

sediment provenance within subduction complexes an example from the aleutian forearc abstract the ultimate composition of any sandstone is affected by a host of primary and secondary factors including the lithologies present in source terranes climate depositional environment and diagenesis in the case of a subduction complex however unequivocal identification of detrital provenance may be impossible because of the cumulative effects of tectonic and sedimentary transport long distance sedimentary transport 1000 km is common within trenches and abyssal plain turbidites can be tectonically transported for long distances as the underlying oceanic basement drifts towards a subduction front post accretionary displacement can occur as a consequence of strike slip faulting and the total distance of tectonic dislocation may reach several thousand kilometers the present day aleutian forearc region north pacific ocean illustrates many of the problems which typify subduction zones several petrologic suites can be identified and there are significant variations in detrital modes in both time and space the aleutian region serves as a sobering modern analog for accreted rock units such as the franciscan complex of california where intercalations of discrete sandstone suites have been noted in the absence of paleomagnetic control interpretations of sediment provenance within ancient subduction complexes probably should be restricted to the generic level

detrital supply from subduction accretion complexes to the eocene oligocene post collisional southern thrace basin nw turkey and ne greece abstract the thrace basin is a large mostly eocene oligocene post collisional sedimentary basin which developed following the closure of the vardar izmir ankara oceanic domain latest cretaceous paleocene sandstone petrologic data framework and heavy mineral analyses and the synthesis of preexisting and new sedimentological observations along representative stratigraphic sections show that the basin fill of the southern thrace basin was mostly derived from the izmir ankara and biga intra pontide subduction accretion complexes to the south proximal facies consistently show northward paleocurrents whereas most paleocurrent indicators measured downcurrent point to an eastward paleoflow likely the result of the deflection of primary gravity flows originated along the southern margin of the basin detrital contributions from the rhodopian basement complex to the west are virtually absent within the southern thrace basin fill conversely rhodopes derived eocene proximal facies in northeastern greece are characterized by a series of coarse grained fan deltas prograding eastward and likely feeding the basin plain turbidites of the depocentral portion of the thrace basin now concealed in the subsurface to the north of our study area arenites of the southern thrace basin are mostly lithic arkoses and arkosic litharenites provenance from the izmir ankara and biga suture zones to the south is characterized by ophiolitic granitoid gneissic low grade metamorphic and extrabasinal carbonate rock fragments as well as by picotite and glaucophane the application of detailed petrographic observations for discriminating paleo vs neovolcanic and penecontemporaneous vs noncoeval terrigenous sands lead to a substantial revision of the geodynamic interpretation of the thrace basin formerly considered a forearc basin a significant penecontemporaneous volcanic component is common in the upper eocene lower oligocene section and can be related to extensive post collisional volcanism following the closure of the vardar izmir ankara ocean the coexistence of pure neovolcanic layers crystal tuffs and cinerites and hybrid arenites rich in penecontemporaneous carbonate grains with sands derived from a continental basement and ophiolitic suites indicates the presence of episutural basins where shallow water carbonates were deposited on top of the exhuming subduction accretion prism these carbonates were mixed with penecontemporaneous neovolcanic and terrigeneous components and redeposited in deeper marine environments

petrogenesis of the ne gondwanan uppermost ediacaran lower cretaceous siliciclastic sequence of jordan provenance tectonic and climatic implications abstract detrital framework modes of the ne gondwanan uppermost ediacaran lower cretaceous siliciclastic sequence of jordan are determined employing the routine polarized light microscope the lower part of this sequence constitutes a segment of the vast lower paleozoic siliciclastic sheet flanking the northern gondwana margin that was deposited over a regional unconformity truncating the outskirts of the east african orogen in the aftermath of the neoproterozoic amalgamation of gondwana the research aims to evaluate the factors governing the detrital light mineral composition of this sandstone the provenance terranes of the arabian craton controlled by plate tectonics appear to be the primary factor in most of the formations which could be either directly inferred employing dickinson s compositional triangles or implied utilizing the petrographic data achieved and the available tectonic and geological data the arabian nubian shield constitutes invariably the craton interior or the transitional provenance terrane within the ne gondwana continental block that consistently supplied sandy detritus through northward flowing braided rivers to all the lower paleozoic formations on the other hand the lower cretaceous series received siliciclastic debris through braided meandering rivers having same northward dispersal direction additionally from the lower paleozoic and lower middle mesozoic platform strata in the arabian craton the formations making about 50 of the siliciclastic sequence represent a success for dickinson s plate tectonics provenance approach in attributing the detrital framework components primarily to the plate tectonic setting of the provenance terranes however even under this success the varying effects of the other secondary sedimentological and paleoclimatological factors are important and could be crucial the inapplicability of this approach to infer the appropriate provenance terranes of the remaining formations could be ascribed either to the special influence of local intracratonic syn rift rhyolitic extrusions where their plate tectonic setting is not represented by the standard plate tectonics provenance diagrams or to the rather unusual effect of the late ordovician glacial event

provenance and tectonic setting of the proterozoic turbidites in hunan south china geochemical evidence the geochemical composition of the middle upper proterozoic turbidites in hunan south china is related to provenance and tectonic setting of the sedimentary basin the turbidites are characterized by moderate sio 2 contents al 2 o 3 sio 2 typically 0 1 0 3 and moderate k 2 o na 2 o ratios generally 0 1 0 3 but relatively high fe 2 o 3 mgo contents 5 10 wt and unusually low contents of cao typically 1 wt abundances of ferromagnesian trace elements and incompatible elements are moderate the ree patterns are uniform and similar to the upper continental crust and typical post archean shales with lree enrichment flat hree and significant negative eu anomalies in general the slates show higher contents of fe 2 o 3 mgo and ferromagnesian trace elements and lower ratios of la sc and th sc than the associated graywackes suggesting that more mafic materials were incorporated into the clay size fraction compared to the upper proterozoic banxi group the middle proterozoic lengjiaxi group has higher concentrations for most ferromagnesian trace elements and lower la sc ratios implying more mafic components in the provenance of the latter the relationship among alkali and alkaline earth elements the chemical index of alteration cia and the th u ratios indicate that the source area was affected by a moderate weathering history the main source was old continental crust the yangtze craton dominated by felsic rocks of magmatic origin with a variable admixture of mafic components from continental island arcs e g the fangjingshan dayong and the sibao yiyang island arc chains the flysch deposition took place in a back arc basin rather than a failed intracontinental rift as proposed by some workers we suggest that suturing between the yangtze and cathaysia blocks did not occur until late proterozoic time and that the final assembly of the supercontinent rodinia in south china was probably marked by the jingning orogeny at 0 8 ga

integrated provenance analysis of a complex orogenic terrane mesozoic uplift of the bogda shan and inception of the turpan hami basin nw china we employ petrographic and advanced geochemical tech niques to better document the evolution of the turpan hami basin based on the unique geologic histories of the arc terranes that served as potential sources of turpan hami deposits first a provenance study of permian through cretaceous sandstone of the turpan hami basin reveals temporal and spatial changes in dominant source ter ranes that provided detritus to the basin volcanic lithic rich upper permian sandstone mean qm 19f18lt63 q p 7lvm89lsm4 q m 48p39k13 followed by more quartzose compositions in triassic sandstone mean qm 41f19lt40 q p 20lvm75lsm5 q m 68p21k11 indicate progressive un roofing of the extinct northern and central tian shan arc terranes to the south of turpan hami a sharp change to sedimentary lithic rich lower jurassic sandstone mean qm 47f16lt37 q p 16lvm42lsm42 qm 75p12k13 overlain by a return to volcanic lithic rich middle ju rassic sandstone mean qm 39f21lt40 q p 14lvm51lsm35 q m 65p21k14 points to the initial uplift and unroofing of the largely andesitic bogda shan to the north which first shed its sedimentary cover as it emerged to become the partition between the turpan hami and southern jung gar basins second geochronological trace element and sm nd isotopic varia tions among granitoids in the late paleozoic tian shan orogenic belt provide a further test of mesozoic uplift of the bogda shan on the basis of previous models of crustal compositions throughout the south central and north tian shan bogda shan and east and west jung gar terranes we infer that isotopically enriched granitic cobbles av erage endi 5 20 50 n 5 6 contained in lower triassic deposits in the north central turpan hami basin were derived from the continen tal crustal central tian shan terrane south of turpan hami and not from the more oceanic north tian shan bogda shan and east and west junggar terranes north of the turpan hami basin we therefore infer that the ancestral bogda shan had not been uplifted by the early triassic and that prior to this time a unified junggar turpan hami basin existed during late permian deposition of extensive lacustrine deposits

an isotopic study of the ni cu pge rich wellgreen intrusion of the wrangellia terrane evidence for hydrothermal mobilization of rhenium and osmium abstract re os sm nd rb sr and oxygen isotope systematics of the wellgreen intrusion in the wrangellia terrane were investigated in an effort to deduce the origin of this mafic ultramafic sill and its attendant ni cu pge deposit radiogenic initial os ratios 1 06 1 82 and sr ratios 0 7044 0 7062 and heavy 18 o 7 3 7 9 suggest alteration of the intrusion by hydrothermal fluids that carried radiogenic 187 os and 87 sr from the surrounding country rocks the great majority 99 of the os however and by inference the other pges derived from a mantle derived magma that suffered little or no interaction with the crust prior to crystallization initial nd isotope ratios are not as variable nd t ranges from 2 02 4 49 and suggest that the rocks were derived from a light rare earth element depleted mantle source the nd results together with os data from relatively undisturbed wehrlites are compatible with either a plume richards et al 1991 or island arc samson et al 1990 model for wrangellia this study contributes to a growing body of evidence that documents the ready mobilization of os in hydrothermal fluids the potential effects of this mobility must be carefully evaluated prior to invoking crustal assimilation to explain variable and radiogenic os initial ratios in layered intrusions

provenance analysis of the voirons flysch gurnigel nappe haute savoie france stratigraphic and palaeogeographic implications the chablais prealps haute savoie france represent a well preserved accretionary wedge of the western alpine tethys they comprise a stack of sedimentary nappes related to palaeogeographic realms ranging from the ultrahelvetic to the southern penninic the provenance analysis is based on the gazzi dickinson method and on qemscan for heavy minerals the quartzose petrofacies is the most important of the two sources and supplied three of the four formations of the voirons flysch it is similar to the sources that fed the other flyschs from the gurnigel nappe it is characterised by a mature quartz rich assemblage and a heavy mineral population dominated by apatite and the zircon tourmaline rutile mineral group these observations suggest a clastic wedge provenance the feldspathic petrofacies is derived from a feldspar rich source associated with metamorphic clasts and a heavy mineral population dominated by garnet this provenance characterises only one formation of the voirons flysch and is related to the axial belt provenance this provenance analysis shows that the middle eocene to early oligocene voirons flysch was fed by two sources in contrast to the other flyschs of the gurnigel nappe and further suggests that this flysch was not deposited in the piemont ocean but in the valais domain based on the results and comparative provenance analysis with the other flyschs of the gurnigel nappe we propose a generic feeding model which involves the sesia dent blanche nappe the sedimentary nappes incorporated in the accretionary prism and probably the brianconnais basement

from static to dynamic provenance analysis sedimentary petrology upgraded abstract the classical approach to sandstone petrology established in the golden years of plate tectonics and based on the axiom that detrital modes of sandstone suites primarily reflect the different tectonic settings of provenance terranes has represented a benchmark for decades the composition of sand and sandstone however simply provides us with a distorted image of the lithological structure of source terranes and gives us little clue whether they are allochthonous or autochthonous orogenic or anorogenic young or old what we may able to see reflected in detrital modes is the nature of source terranes continental arc oceanic and the tectonostratigraphic level reached by erosion in space and time the proposed new approach to the petrology of sand and sandstone 1 starts with a simple classification scheme circulated since the 1960s which is purely descriptive objective and free of ill defined ambiguous terms and 2 focuses on the nature and tectonostratigraphic level of source terranes further steps are essential to upgrade provenance analysis acquiring knowledge from modern settings is needed to properly identify and wherever possible correct for physical and chemical processes introducing environmental and diagenetic bias and thus address nature s complexities with adequate conceptual tools equally important is the integration of multiple techniques ideally including bulk sediment multi mineral and single mineral methods bulk sediment petrography remains the fundamental approach that allows us to capture the most precious source of direct provenance information represented by the mineralogy and texture of rock fragments bulk sediment geochemistry applicable also to silt and clay carried in suspension is a superior method to check for hydraulic sorting chemical weathering and fertility of detrital minerals in different sediment sources detrital geochronology thermochronology and isotope geochemistry reveal the diverse time structures of source rocks and have become necessary complementary techniques in modern provenance analysis inferences on geodynamic processes need independent geological information and come last but if tackled properly they can lead us much farther than the standard label obtained by using triangular diagrams uncritically as if they were infallible oracles

geochemistry of permo triassic mudstone of the satpura gondwana basin central india clues for provenance abstract major and trace element data of the permo triassic mudstones from the intracratonic satpura gondwana basin central india have been used to investigate provenance the satpura succession 5 km thick unconformably overlies the precambrian basement sediment dispersal pattern suggests that the precambrian rocks straddling the southern margin of the satpura basin were the most probable source for the sediments the lowermost unit of the satpura succession comprises glacio marine and glacio fluvial deposits the rest of the succession largely represents a variety of fluvial depositional systems with some records of fluvio deltaic and fluvio lacustrine sedimentation under a climatic spectrum of temperate humid to warm semi arid the present study is confined to the lower six formations namely talchir barakar motur bijori pachmarhi and denwa arranged in that order from bottom to top the oldest rocks of this sequence the talchir formation are enriched in mobile elements such as na ca and mg depleted in alumina and have high icv 0 93 1 29 and lower cia values 61 82 74 89 compared to those of the younger mudstones k 2 o al 2 o 3 ratios of the talchir mudstones 0 24 0 28 are higher than the younger mudstones in this sequence these results suggest that the talchir mudstones were weathered less intensely and are thus more immature than the younger mudstones this is consistent with the prevailing cold climate and relatively higher rate of basin subsidence in contrast the majority of the mudstones from the younger formations are depleted in mobile elements have relatively low icv 0 18 0 87 and k 2 o al 2 o 3 values 0 07 0 26 higher cia values 76 99 92 86 and appear compositionally more mature reflecting moderate to high intensity source rock weathering among them the barakar mudstones likely have been more intensely weathered than mudstones from any of the other formations the trace element compositions and ratios are consistent with most mudstones being derived from a felsic source with some mudstones being derived from a more mafic source for example la sc 0 805 and 0 114 la th 6 245 5 072 7 418 6 245 and 5 072 and eu eu 1 431 0 868 and 0 805 of some mudstones indicate mafic source bivariate plot of th sc and zr sc indicates considerable enrichment of zircon that suggests recycling from meta sedimentary rocks prominent negative eu anomaly high lree hree and flat hree pattern reflect sediment derivation from predominantly felsic rocks of the old upper continental crust sio 2 al 2 o 3 versus k 2 o na 2 o plot for the mudstones suggests that they formed in a passive margin also total ree content of most of the mudstones is conformable with passive margin tectonic setting and craton interior type of provenance plotting in la th sc th sc zr 10 and la sc versus ti zr diagrams largely indicates continental margin settings for majority of the mudstones but fails to differentiate between active and passive continental margins

re os isotope systematics for the lince estefania deposit constraints on the timing and source of copper mineralization in a stratabound copper deposit coastal cordillera of northern chile the lince estefania stratabound copper deposit in the michilla district is one of the most important deposits in the coastal cordillera of northern chile and is one of the most representative of this type of deposit chalcocite and bornite characterize the main stage of hypogene copper sulfide mineralization rhenium and osmium isotopes are used here to constrain the age of hypogene mineralization and the source of osmium contained in these ore minerals a re os isochron yielded an age of 160 16 ma 2 with an associated initial 187os 188os ratio of 1 06 0 09 mean square of weighted deviates 1 8 this age is consistent with available geochronological data from volcanic rocks that host the mineralization and associated alteration phases the high initial 187os 188os ratio indicates a lower crustal component for the source of os and by inference the cu sulfides that contain this os late hematite occurs as an isolated phase or more commonly is associated with the chalcocite bornite and supergene chalcocite covellite associations analyses performed on pure hematite indicate a disturbance of the re os system and hence this mineral phase is not useful as a re os geochronometer

provenance of the carboniferous hochwipfel formation karawanken mountains austria slovenia geochemistry versus petrography this study focuses on the carboniferous sediments of the karawanken mountains austria slovenia to identify possible source areas and their geotectonic setting provenance analyses have been applied using petrographical and geochemical approaches what also lead to an evaluation of the used methods within the hochwipfel formation five stratigraphic related petrofacies groups can be defined using the sandstone component inventory homogenous provenance results based on major element and trace element data suggest an active continental margin continental island arc with probably an intraplate signature provenance analyses of light minerals point to source areas with basement rocks mainly metamorphic arc material and sedimentary rocks in combination the rapid and highly variable change of provenance signatures within the stratigraphic succession of the petrofacies types excludes a single provenance in the western part of the karawanken mountains additionally changes in composition of the individual petrofacies groups correlate with the stratigraphy in the eastern part varying contents of garnet chromite hornblende and epidote within the sedimentary succession of the hochwipfel sandstones can partly be attributed to geodynamical changes in the hinterland the chemical compositions of garnets tourmalines and chromites confirm the results of both geochemistry and sediment petrography in a quantitative approach based on petrography we can see an equal mixture of all source areas whereas quantification with a geochemical approach results in c 11 of material that can be attributed to a passive continental margin source 28 to 37 to an active continental margin c 44 to a magmatic arc setting and 16 to 19 to an oceanic within plate source area the resulting model for the geodynamical setting of the hochwipfel basin during the late palaeozoic can be best explained by a forearc basin in the eastern part and various pull apart basins in the western part connected through bypasses at the continental margin of gondwana and the palaeotethys as an additional outcome this study clarifies that geochemically derived provenance results based on bulk rock and mineral composition recognize best complex geodynamical settings and a mixture of sources since they incorporate best the provenance significant lithic components on the other hand it points out that an application of additional petrological approaches does not necessarily lead to further information and an elimination of errors but could be essential to define general information of the investigated stratigraphy like the correlation of deposits with stratigraphy petrofacies groups

stratigraphic constraints on the development and timing of arc continent collision in northern papua new guinea abstract the finisterre mountains of northern papua new guinea are the site of an active southeast propagating collision between the finisterre terrane and the australian continental margin the clastic sedimentary sequence on the southern flank of the range records the history of the collision the age of initial collision can be deduced from the second of two provenance shifts that occur in the sequence as revealed by a study of 69 dated sandstones the first shift at about 16 18 ma was from volcanolithic sediments to mixed provenance sediments rich in quartz and metasedimentary lithic fragments these latter sediments were probably derived from the orogenic belt active along the australian continental margin at that time at 3 0 3 7 ma the volcanic source was rejuvenated initial collis on at this time uplifted the finisterre terrane causing the provenance shift here we break the stratigraphic sequence into three units the sarawaget beds the erap structural complex and the leron formation the sarawaget beds are middle eocene to early miocene volcanolithic sandstones that were deposited as clastic aprons un the flanks of the finisterre volcanic are volcanic activity ceased in the early miocene the erap complex is divided into two clastic subunits the sukurum and nariawang units and one basaltic subunit the gorambampan unit the sukurum unit consists of turbidites deposited south of the extinct finisterre arc from the latest early miocene through the early pliocene much of the sediment in the unit was derived from low to medium grade metasedimentary units on the active northern margin of the australian continent renewed subduction i the late miocene or pliocene occurred along the new britain trench just south of the remnant finisterre arc closing an eastward widening small ocean basin the sukurum unit probably represents an accretionary prism that formed at this subduction zone scattered seamounts that were scraped off the downgoing plate are preserved as the gorambampan unit initial collision of the finisterre terrane with the continental margin at 3 0 3 7 ma uplifted the paleogene volcanic rocks which were rapidly eroded and deposited as the volcanolithic turbidites of the nariawang unit southeastward propagation of the collision tip caused incorporation of the nariawang unit into the accretionary wedge rapid uplift raised the terrane foreland above sea level sometime after 1 3 mo the fluvial lacustrine and marginal marine deposits of the leron formation accumulated in a terrane foreland basin that developed south of the collision zone further propagation of the thrust front toward the foreland incorporated the leron formation into the fold and thrust belt rapid uplift of the finisterre range and voluminous volcanolithic sedimentation continue to the present in the finisterre range arc continent collision is marked by a provenance shift from metasedimentary and quartzose detritus to volcanic detritus in another modern arc continent collision on taiwan collision has caused a shift from volcanic to metasedimentary detritus we attribute this discrepancy to the presence of the finisterre terrane an extinct arc in the forearc region of the finisterre arc continent collision and the absence of a similar terrane in the forearc area on taiwan the very different evolution of sandstone provenance in the active taiwan and finisterre collision zones shows that local factors can profoundly influence the provenance histories of collision zones no one model of sediment provenance evolution can characterize all collision zones whether modern or ncient

paleoclimatic control on the composition of the paleoproterozoic serpent formation huronian supergroup canada a greenhouse to icehouse transition unlike other feldspathic arenites in the 12 km thick huronian supergroup strata of the 250 350 m thick serpent formation contain abundant plagioclase deposited in a distal alluvial setting the serpent formation consists of arenites with minor shale and siltstone the plagioclase abundance could reflect unroofing of a unique source relative to other huronian units or could be due to less intense chemical weathering major trace and rare earth element ree geochemistry of the serpent formation are used to evaluate these two possibilities serpent formation source rocks form part of the archean superior province which mainly consists of tonalitic granitic and supracrustal assemblages and their metamorphosed equivalents in al2o3cao na2ok2o acnk space shales define a linear array which indicates that the unweathered source contained plagioclase and k feldspar in the ratio of 5 1 this particular array indicates that serpent fluvial systems tapped a variably weathered carapace developed on the superior province rather than purely fresh bedrock a modelled mixture of 80 tonalite and 20 granite group rocks reproduces ree and trace element characteristics of the serpent formation sandstones and shales average eu eu 0 87 lan smn 4 4 gdnybn 1 8 and th sc 1 65 mass balance considerations indicate that less than 5 supracrustal group rocks can be added at the expense of the granite group a unique source for serpent detritus is rejected because underlying and overlying units have approximately the same provenance composition plagioclase k feldspar ratios in serpent sandstones range from 2 1 to 1 2 which achieves mass balance among source mudstone and sandstone compositions when plotted in acnk space achievement of mass balance implies that sandstones and mudstones were derived from the same weathering profiles these findings indicate that plagioclase preservation in the serpent formation is related to less intense compared with other huronian arenites paleoweathering conditions probably a harbinger of the widespread continental glaciation recorded in the overlying gowganda formation

development of the cote d ivoire basin reading provenance sediment dispersal and geodynamic implications from heavy minerals the combined approach of conventional and varietal heavy mineral analysis was applied to constrain changes in source rock area dispersal routes of detritus and geodynamic setting of the upper cretaceous to neogene cote d ivoire basin the heavy mineral assemblage of albian to turonian sediments reflect a narrow source rock area and short transport distances a prominent change in the heavy mineral association of late cenomanian to neogene sediments indicates enlargement of source area and longer fluvial transport distances or longer storage of sediment within the littoral energy fence the sudden change within the heavy mineral associations marks the transition from the late syn rift stage to the early passive margin stage of the southern atlantic during albian to late cenomanian time the basin geometry was mainly controlled by steep slopes and sediments were transported directly to the depocenter the situation changed in late cenomanian time a small shelf area developed where sediments from different sources were mixed and reworked before deposition we believe that the w e direction of the long shore drift which transports today huge quantities of near shore sand was established at the end of the paleogene this resulted from the drifting of southern west africa across the paleoequator and subsequent change in surface wind directions

stratigraphic architecture of an experimental basin with interacting drainages abstract the stratigraphic architecture of intracontinental rift basins is defined by a dynamic relationship between depositional processes associated with the basin floor and flanking tributary streams the resulting depositional belts are sensitive to a variety of factors including basin geometry subsidence rate and sediment discharge the experimental earthscape run in 2006 xes06 examined the development of fluvial morphology and alluvial architecture as a function of subsidence and sediment flux in an experimental basin based on the form of a simple half graben sediments from tributary drainages were introduced into the axial stream through toe cutting and realignment of transverse drainage courses to parallel the prevailing axial flow direction transverse sediment contributions to the axial stream were almost equally apportioned over a wide range of sediment discharges tested in the experiments sediment tracers showed a larger contribution of footwall derived sediment into the axial belt probably due to more frequent and aggressive toe cutting by axial streams changes in the axial transverse deposit boundary to external forcing by subsidence and sediment discharge and relatively rapid intrastage stabilization of the depositional belts resembles the large scale self organization observed in moving boundaries that define the morphology of fluviodeltaic systems basin sedimentation was matched to subsidence in order to maintain a constant base level which made the location and width of the axial belt sensitive to the relative sediment fluxes from the transverse systems rather than the axis of maximum subsidence the asymmetrical subsidence pattern and the transverse fan morphology influenced the preservation of sedimentary sequences stage bounding stratigraphic lacunae were well preserved in the hanging wall succession providing a reliable record of basin development

the functioning of sediment routing systems using a mass balance approach example from the eocene of the southern pyrenees abstractsediment routing systems link source regions undergoing erosion with depositional sinks and involve a volumetric or mass budget understanding how these source to sink systems function is key to stratigraphic prediction but estimation of their surface sediment discharges and depositional fluxes on geological time scales is a challenging problem we recognize a paleosediment routing system from the geological record in the mid late eocene escanilla formation and time equivalents of the tectonically active wedge top region of the southern pyrenees by mapping the 200 km long fairway of the escanilla sediment routing system we obtain the sediment budget and grain size fractionation of three time intervals each of 2 5 2 6 m yr duration over the time period 41 6 33 9 ma four thousand cubic kilometers of sediment sourced principally from two feeder systems in the high pyrenees was deposited in a period of 7 7 m yr the positions of moving boundaries characterized by rapid reduction in the perc

inorganic geochemistry of the type caradoc series sandbian to middle katian upper ordovician onny valley shropshire uk the geochemistry and petrology of the type section of the caradoc series in the onny valley indicate that it was deposited on a marginal basin continental shelf similar to the western side of the present sea of japan the lower beds form a transgressive regressive sequence in which the rocks become less mature upwards all the coarser sediments above the basal quartzites and conglomerates are greywackes in which the apparent muddy and ferrous matrix is due to the breakdown of unstable minerals and particles higher values of na 2 o and na k ratios are found in the coarser shallow water sandstones of the horderley sandstone formation and decrease markedly in the succeeding beds accompanied by an increase in k 2 o higher values of carbonate corrected and hence related other major and minor elements like sio 2 cao p 2 o 5 mno and most trace elements correlate with the transgressive systems and maximum flooding surfaces of the three sequences recognized where they are related to condensation at those horizons chemical indices of alteration cia suggest that the horderley sandstone formation underwent greater predepositional physical weathering than lower and higher beds which is compatible with the petrography and were deposited during a cool phase within overall warm sandbian katian times trace element ratios suggest an oxic to suboxic depositional environment

the detrital record of cretaceous to pliocene sandstones across the ne south american margin the cretaceous to pliocene erosional history of the ne south american margin depicts the increasing influence of the uplifting caribbean mountain belt petrographic analyses of 59 cretaceous to late pliocene sandstone samples derived from across the islands of trinidad and barbados demonstrate systematic mineralogical changes whereby early cretaceous arkosic arenites gave way to mature quartz arenites by the late cretaceous and caribbean mountain derived lithic rich arenites during the neogene changes in the framework compositions are accompanied by changes in textural attributes with caribbean mountain detritus being notably finer grained than cratonic input silica cements predominate in quartzose sandstones and sericitic and clay cements within litharenites the changing mineralogical compositions record the gradual deformation of the northern south american passive margin and initiation of the andean caribbean mountain foreland basin system with incipient orogenic detritus evident from the latest eocene and unambiguous orogenic input by the late oligocene the preponderance of finer grain sizes within deltaic pliocene sandstones records the later fill of an established foredeep with sediments sourced primarily from erosion of the andean hinterland these interpretations agree with heavy mineral compositional changes and the timing of uplift from geo and thermo chronological data across the margin supplementary material qualitative descriptions sample coordinates and raw point counts are available at https doi org 10 6084 m9 figshare c 3659381

composition and provenance history of late cenozoic sediments in southeastern bolivia implications for chaco foreland basin evolution and andean uplift abstract the chaco foreland basin marks the eastern edge of the andean orogenic system and contains up to 7 5 km of mostly nonmarine siliciclastics thus providing an opportunity to study the detrital record of late cenozoic andean geodynamics and paleogeography sandstones from the southern bolivian chaco foreland basin testify to variable contributions from the craton and the andean foreland fold and thrust belt in the context of an eastward advancing orogen sandstone and conglomerate petrography of the oligocene to recent strata exposed in the chaco basin show an overall trend towards reduced mineralogical maturity corresponding to diminishing transport distance increasing topographic gradient and changing depositional environment from arid continental plain oligocene to middle miocene petaca sandstone through marginal marine middle miocene to late miocene yecua sandstone and braided fluvial settings late miocene tariquia sandstone to semihumid alluvial fan environments late miocene to recent guandacay and emborozu formations paleocurrent patterns of pre tectonic sediments record westward transport the late miocene transitional marine yecua formation sediments show a complex shoreline related pattern syntectonic strata tariquia guandacay and emborozu formations filling the foreland basin indicate dominant east directed sediment transport from the advancing andean orographic front because the eastern cordillera provided a drainage barrier to altiplano erosion sandstones of the chaco basin do not directly record andean volcanism or altiplano uplift however climatic inferences from changing facies and petrographic composition suggest major uplift and formation of orographic barriers between 14 and 7 ma

detrital record of neoproterozoic arc magmatism along the nw margin of the yangtze block china u pb geochronology and petrography of sandstones abstract neoproterozoic conglomerate sandstone successions with abundant volcanic components ranging from 750 to 2200 m in thickness occur along the northwestern margin of the yangtze block they were previously regarded as sinian tillites and typical platform sediments or the fills of a passive margin rifted basin or arc related basin in chinese literature crude ripple parallel normal and inverse grading structures suggest together that these conglomerate sandstones were deposited by subaqueous debris flows and high density turbidity currents new shrimp zircon u pb results from a tuffaceous interlayer with syn sedimentary deformation indicate deposition at 797 ma sandstone detrital clasts and conglomerate composition analysis suggest that volcanic sedimentary and granitoid rocks were exposed to erosion in their source area in terms of primary components these conglomerate sandstone successions with tuffaceous interlayers along the northern margin of the yangtze block are similar in composition to other sandstones from the magmatic arc detrital modal analysis indicates that they were derived from a continental arc hannan complex and accumulated in a forearc basin

beach sands from baja california peninsula mexico abstract fifty beach locations were sampled in baja california peninsula mexico in order to characterize textural and compositional parameters the western beach sands are mainly associated with a lower relief coastal plain and high energy of waves and currents with the beach sands of the eastern littoral zone finer better sorted and low carbonate and rich quartz and feldspar contents are observed for the western beach sands when compared to the eastern beach sands the mineralogical maturity and provenance index are greater for the western beach sands than for the eastern beach sands these contrasts may be explained by differences on coastal plain relief and differences on hydrodynamic energy of waves and currents that are responsible for the rock fragment dilution by enrichment of more stable quartz debris finally some distinctions were found for na2o k2o cao values this is thought to be a result of the presence of some samples from the eastern coastline with higher values in cao content probably due to the presence of basaltic rocks

the influence of climate and topography on rock fragment abundance in modern fluival sands of the southern blue ridge mountains north carolina chemical weathering influences the detrital composition of sand size sediment derived from source areas subject to different amounts of precipitation in the coweeta basin north carolina of the grain types studied rock fragments are most sensitive to chemical degradation therefore their abundance is the best indicator of cumulative weathering effects destruction of sand size rock fragments by chemical weathering is a function of both the intensity and duration of chemical weathering experienced by grains in regoliths of the source area in the coweeta basin the intensity of chemical weathering is directly related to the climate via effective precipitation in individual subbasins whereas the duration of chemical weathering is inversely related to the relief ratio of the watershed therefore soils in watersheds with low relief ratios and high discharge per unit area experience the most extensive chemical weathering and sediments derived from these watersheds contain the lowest percentage of rock fragments the effects of climate alone cannot explain the systematic variation of rock fragment abundance in sediments from the coweeta basin the compositional imprint left on these sediments by chemical weathering is a function of both climate and topographic slope in the sediment source area

provenance and depositional environment of rhenohercynian synorogenic greywackes from the giessen nappe germany the giessen nappe of the south eastern rhenish massif can be subdivided into a northern group and southern group of frasnian lower carboniferous greywackes that differ slightly in their sedimentology clast petrography heavy mineral assemblages and bulk geochemistry

sandstone detrital modes in the makran accretionary wedge southwest pakistan implications for tectonic setting and long distance turbidite transportation detrital modes of early miocene to early pliocene sandstones from the makran accretionary wedge in southwest pakistan show a mainly quartzolithic composition with an evolution from the transitional recycled to quartzose recycled the lithic types however indicate two distinct petrofacies accreted abyssal plain turbidites have qp11lvm27lsm62 and lm39lv27ls34 showing a predominant supply from sedimentary and metasedimentary source terranes whereas slope and shelf facies sediments deposited on the accretionary wedge have qp7lvm47lsm47 and lm22lv48ls30 due to an increase of volcanic detritus the detrital modes of the abyssal plain sediments suggest a recycled orogenic source probably the himalayan collision zone the facies and longitudinal dispersal pattern suggest deposition in an oligo miocene analogue of the present indus fan the sediment must have been transported across strike parallel to the transform structure linking the makran wedge to the himalayas chaman ornach nal fault system and fed into the fan at the western end of the subduction zone the detrital modes also show an increase in volcanic detritus with time lv l 0 27 for the early miocene abyssal plain sediments to 0 47 for the slope sequences this may have been derived from late mesozoic volcanic terrains in northern baluchistan or the ladakh himalayas or more probably from the early to middle miocene andesitic volcanic centre in the northern makran

climatic and tectonic influences on fan deltas and wave to tide controlled shoreface deposits evidence from the archaean keskarrah formation slave province canada the 2 6 ga keskarrah formation located in the central slave province northwest territories canada is a late orogenic tectonically controlled sedimentary sequence that developed under unusual climatic and depositional conditions the formation is adjacent to the crustal scale north trending beniah lake fault and overlies the 3 15 ga augustus granite the 2 69 2 7 ga mafic volcanic peltier formation and the turbiditic contwoyto formation unconformably principal lithofacies in the keskarrah formation include conglomerate sandstone and siltstone sandstone the conglomerate lithofacies represents coalescing gravelly streamflow dominated fan deltas adjacent to topographic highs up section quartz rich arenites and quartz arenites of the sandstone lithofacies are interpreted to be shallow water shoreface deposits influenced by wave action and tides the overlying feldspathic litharenites of the siltstone sandstone lithofacies are consistent with a lower shoreface to proximal offshore environment dominated by wave and tide interaction tidal influence in both sandstone dominated lithofacies is inferred from the presence of mudstone laminae between bedforms and on foresets of cross beds as well as from abundant reactivation surfaces with local mudstone drapes intense chemical weathering during the archaean resulting from elevated atmospheric co2 levels higher temperatures and moist climatic conditions played an important role in the development of quartz rich arenites that appear to be first cycle deposits few lithic fragments and feldspar grains are preserved due to in situ host rock weathering chemical weathering during transport and wave and tide action hydraulic sorting and abrasion in the shoreface environment contributed to the continued breakdown and transport of labile minerals increased proportions of lithic fragments in sandstone beds of the conglomerate lithofacies are the result of shorter transport distances from source areas to the depositional environment abundant conglomerate with up to 4 m large granitic boulders derived from the adjacent augustus granite and mafic clasts from the peltier formation indicate high relief and fault related uplift and subsidence the intimate association of fan deltas and wave and tide influenced shallow marine deposits in association with quartz rich sandstones forming in a high relief area make the keskarrah formation remarkable in the rock record

a combined petrographical geochemical provenance study of the newland formation mid proterozoic of montana a provenance study was conducted on the mid proterozoic newland formation in which petrographical features of sandstones and geochemical characteristics of shales were integrated to arrive at an internally consistent interpretation sandstones of the newland formation are typically arkosic sands and arkoses with very well rounded quartz and feldspar grains and only minor amounts of extrabasinal rock fragments the predominant feldspar types are k spar and microcline feldspar grains are smaller than quartz grains and feldspars show little alteration due to weathering detrital modes of newland sandstones qfl diagrams indicate that they were derived from a stable cratonic source these petrographical features imply a source area dominated by granites and granitoid gneisses semi arid to arid climate tectonic quiescence and overall peneplain conditions shales of the newland formation are dominated by illite quartz silt and fine crystalline dolomite they have small la th rations relatively large hf contents and small contents of cr co and ni all indicative of derivation from crust of granitic composition small tio 2 al 2 o 3 ratios also suggest source rocks of granitic composition the average chemical index of alteration cia for newland shales is 71 8 which in light of the probable granitoid source indicates modest amounts of chemical weathering relatively large sio 2 contents and large k 2 o na 2 o ratios reflect derivation from stable cratonic areas and tectonic quiescence thus in general the petrography of sandstones and geochemistry of shales provides the same provenance clues for the newland formation one notable discrepancy between the two approaches is that the sandstones indicate an arid to semi arid climate with very minor chemical weathering whereas the cia of the shales indicates at least modest amounts of chemical weathering this indicates on one hand the need to better calibrate the cia with a large variety of muds from modern climatic settings and on the other hand the possibility that this discrepancy is due to transport segregation

geochemical discrimination of clastic sedimentary rock sources abstract factors controlling the geochemistry of a clastic sedimentary rock can include 1 composition of source terrain 2 chemical weathering 3 hydraulic sorting 4 diagenesis 5 metamorphism and 6 hydrothermal alteration a linear solution inferring source terrain composition from geochemistry of the sediment is impossible in this multivariate system as several unknowns will commonly be present the use of graphical analysis of element pairs circumvents the problem chemically immobile elements will maintain invariant ratios during rock mass change caused by either addition or depletion of mobile elements this results in chemically immobile element scattergrams exhibiting linear trends along radians extending from the origin if the major mineral phases of the immobile elements have behaved in a hydrodynamically similar manner as chemically mobile element plots will produce a scatter of points this relationship can be used to test chemical immobility and similarity in hydrodynamic sorting history the constraint on analysis is that the source area must be compositionally uniform or the sediment well mixed prior to delivery to the basin a second technique using sio2 plots has also been developed to investigate element mobility and hydrodynamic behaviour of the mineral phases containing the elements sio2 immobile element plots result in a linear arrangement of points extending towards either 0 or 100 sio2 the 0 intercept position occurs for elements with major mineral phases concentrated in sand the 100 intercept for those concentrated in clays plotting chemically mobile elements produces different patterns and this can be used to gain information on alteration and sorting history elemental ratios for chemically immobile elements with similar hydrodynamic behaviour will be the same as those for the weighted average composition of the source material this provides a powerful tool for deducing source terrain from sediment geochemistry techniques outlined above were tested on archaean metasandstones from superior province canada immobile element ratio diagrams for nb al ti and zr al ti indicate that a calc alkaline extrusive intrusive suite lying to the north of the study area was the source and not five other volcanic suites in the region this conclusion agrees with previous clast lithology studies and accentuates the applicability of the geochemical techniques

geochemistry and petrology of recycled orogen derived sediments a case study from upper precambrian siliciclastic rocks of the central iberian zone iberian massif spain abstract two areas of upper precambrian siliciclastic rocks separated from each other by 150 km were selected in the central iberian zone ciz for a petrological and geochemical study the petrology of the coarser grained rocks indicates the absence or scarcity of igneous clasts the presence of extrabasinal and intrabasinal clasts and homogeneous features of sandstones ranging from very fine to fine grained the modal data of these rocks plot close to the qt l and qm lt sides of qtfl and qmflt triangular diagrams suggesting provenance from a recycled orogen the geochemical data on the shales and sandstones from the two areas studied are very uniform both groups of rock show similar ranges of relevant major element ratios such as al 2 o 3 tio 2 17 46 21 51 17 46 21 34 for shale and sandstone respectively al 2 o 3 feo t 2 40 3 79 2 18 3 33 and feo t feo t mgo 0 71 0 77 0 68 0 76 together with parallel average rare earth element ree patterns and similar values for some key trace element ratios la th th yb th u zr hf sm nd and cr sc other trace element ratios la sc th sc cr th and cr zr are uniform in the shales group and also in the sandstones group although minor differences become apparent when both groups are compared these differences are probably related to the quartz dilution effect affecting the relative abundance of phyllosilicates in these rocks and indirectly the sc and cr contents given their covariations with al2o3 the zr yb zr y and zr th ratios of the shales are uniform the sandstones show higher and more variable values and there is no correlation between zr abundance and any of these ratios in the shales or sandstones together with the parallel ree patterns shown by both groups of rock these results suggest the absence of heavy mineral fractionation during the transport of detrital material and or the relative importance of other minerals probably phyllosilicates in the control of yb y and th abundances apparently all the groups of rocks show a remarkable geochemical homogeneity despite the distance between the sampling areas thus the petrological and chemical data are consistent and point to a very extensive homogeneous and stable source region as the most plausible contributor to the upper precambrian siliciclastic rocks in the ciz the possible relationship between this zone and n gondwana is also discussed

petrographic evidence of different provenance in two alluvial fan systems palaeogene of the northern tajo basin spain palaeogene detrital deposits of the northern tajo basin are coalescent alluvial fan systems interfingering distally with lacustrine carbonates non carbonate extrabasinal clasts increase to the east while carbonate extrabasinal clasts decrease rock fragments increase to the west while the feldspar quartz ratio remains constant rock fragments define two sedimentary domains the iberian in the east was derived from mesozoic rocks of the iberian range and the central system to the west was derived from cretaceous cover and palaeozoic metamorphic basement evolution of sandstone composition is related to erosion of the source areas and is different in the two domains the tectonic setting is apparently recycled orogen providing calcareous rock fragments are included in the total lithic clasts

exceptions to the relationship between plate tectonics and sandstone composition abstract routine use of qfl qplsmlvm and lmlslv plate tectonic provenance diagrams has led to the recognition of error populations for these sandstones the interpretation of tectonic setting based on data exclusive of petrography does not coincide with the interpretation of tectonic setting based on their location on compositional diagrams the anomalous sandstones can be separated into at least four categories i sandstones deposited during the transition between tectonic regimes may be derived in part from relict source rocks ii the relative enrichment of sandstones in detrital quartz by weathering and or depositional reworking may lead to an inaccurate interpretation of tectonic setting from compositional data iii sandstones deposited in tectonic settings as yet unrepresented on he provenance diagrams may plot between the provenance fields or overlap existing fields iv the role of detrital carbonate rock fragments directly affects the location of data points on provenance diagrams and is an unresolved problem the first two categories represent permanent problems in the use of sandstone composition as an indicator of plate tectonic setting whereas the last two may only be temporary problems that can be solved by more data and a consensus on determining detrital modes recognition of anomalous sandstones in the rock record will reduce the probability of erroneous interpretations of tectonic setting and enhance the use of sandstone petrology as an indicator of plate tectonic setting

clastic metasediments of the early proterozoic broken hill group new south wales australia geochemistry provenance and metallogenic significance whole rock analyses of samples of pelite psammite and psammopelite from the early proterozoic broken hill group willyama supergroup in the broken hill block new south wales australia reveal distinctive geochemical signatures major element data show high al2o3 and k2o low mgo and na2o and relatively high fe2o3tmgo ratios compared to average early proterozoic clastic metasediments high field strength elements hfse are especially abundant including nb most 15 27 ppm ta most 1 0 2 2 ppm th 17 36 ppm hf 4 15 ppm and zr most 170 400 ppm y 33 74 ppm is also high concentrations of ferromagnesian elements are generally low sc 20 ppm ni 62 ppm co 26 ppm cr most 100 ppm data for rare earth elements rees show high abundances of light rees lacn 116 250 chondrite lacn 437 in one sample high lacnybcn ratios 5 6 13 9 and large negative eu anomalies eueu 0 32 0 57 the geochemical data indicate derivation of the metasedimentary rocks of the broken hill group by the erosion mainly of felsic igneous or meta igneous rocks high concentrations of hfse y and rees in the metasediments suggest a provenance dominanted by anorogenic granites and or rhyolites including those with a type chemistry likely sources of the metasediments were the rhyolitic to rhyodacitic protoliths of local quartz feldspar biotite garnet gneisses e g potosi type gneiss that occur within the lower part of the willyama supergroup or chemically similar basement rocks in the region alternative sources may have included early proterozoic anorogenic granites and or rhyolites in the mount isa and or pine creek blocks of northern australia or in the gawler craton of south australia metallogenic considerations suggest that the metasediments of the broken hill block formed enriched source rocks during the generation of pegmatite hosted deposits and concentrations of la ce nb ta th and sn in the region li be b w and u in pegmatite minerals of the district may have been acquired during granulite facies metamorphism of the local metasediments

ore mineralogy fluid inclusion and stable isotopic characteristics of stratiform copper deposits in the coastal cordillera of northern chile late jurassic stratiform copper deposits in the coastal range of northern chile susana lince and buena vista of the carolina de michilla district and mantos de la luna are hosted in an andesite dominant volcanic pile of the jurassic la negra formation which is extensively intruded by gabbroic to granodioritic plutons and dikes primary copper mineralization is characterized by chalcocite cu1 90s digenite bornite chalcopyrite hematite supergene alteration of these minerals has produced chalcocite djurleite covellite atacamite chrysocolla and copper oxides copper wad fluid inclusion data indicate a variable temperature of formation 200 to 380 c and a wide range of fluid salinities 7 to 34 wt nacl carbon and oxygen isotopic compositions of calcite from the susana lince deposit 13c 2 6 to 3 6 18o 13 7 to 18 7 combined with the thermometric data suggest that the fluid responsible for the calcite mineralization derives from mixing of high temperature meteoric water with cooler basinal brines these data imply that the stratiform copper deposits of the coastal cordillera are epigenetic and formed from non magmatic moderately oxidized hydrothermal solutions

petrography and geochemistry of holocene sands in the western gulf of mexico implications for provenance and tectonic setting abstract petrographic and geochemical analysis of recent fluvial beach and dune sediments derived from the same source terrane was carried out in the western gulf of mexico to show the usefulness of the these three environments in determining the tectonic setting of the source petrographic analysis showed that dunes concentrate the less heavy minerals and quartz grains by means of the selectiveness of the wind as a transport agent in contrast the heavier grains such as the rock fragments remain in the beach and fluvial environments because of the high transport energy beach and dune sands do not define a particular tectonic setting because of the selective wind action of the backshore of the beach and the dune environments and the less intense chemical weathering the fluvial sands are the most representative in terms of interpretation of tectonic setting because they reflect the volcanic domain of the source rocks of the trans mexican volcanic belt the geochemical results of all three sedimentary environments reflect the calcalkaline character of the igneous source rocks of the trans mexican volcanic belt the samples fall in a continental island arc margin field with basaltic and andesitic source rocks a correlation and factor analysis indicates an alkali basalt source that contributes to the composition of the beach dune and fluvial sediments the geochemical analysis of the sediments more accurately reflects the tectonic setting regardless of the depositional setting of the sediments

compositional variations in deep sea gravity flow deposits a case study from the voirons flysch voirons wagital complex chablais prealps france abstract grain size control is frequently invoked to explain the compositional variation of detrital sediments in fluvial sediments a similar possibility is here investigated in the fossil deep sea gravity flow deposits from the voirons flysch voirons wagital complex chablais prealps about 270 samples of diverse depositional settings were analysed using the framework composition including cement and porosity mutti facies and grain size measurements six lithofacies have been identified from cluster analysis they correspond to channel l1 to l3 and lobe l4 and l5 depositional settings and to reworked turbidites l6 our results emphasize the close relationship between petrography and grain size which alters the detrital signal from extrabasinal sources the abundant polycrystalline component of proximal deposits is progressively removed while skeletal grains and additional intrabasinal grains become more abundant in distal deposits alongside porosity is reduced by the simultaneous increase of cement which constrains subsequent diagenetic modifications hence proximal depositional settings keep most of the inherited signal from extrabasinal sources whereas distal deposits will be homogenised when plotted in provenance analysis diagrams the successive depositional settings show distinct fields possibly corresponding to different tectonic settings of the dickinson model this compositional variation thus creates a bias in provenance interpretation resulting from both grain size control and flow mechanisms finally our results emphasize that petrographic data must be handled with care in provenance analyses especially when comparing various deep sea gravity flow systems with different grain size ranges

tectonic environment of the devonian gramscatho basin south cornwall framework mode and geochemical evidence from turbiditic sandstones the portscatho formation within the allochthonous unit of the middle and upper devonian gramscatho group is a thick sequence of deep water sandstones and interbedded slates deposited by southerly derived turbidity currents into the gramscatho basin of south cornwall throughout an approximately 3 5 km thick sequence the portscatho formation is petrographically and chemically coherent except that the upper section shows a higher proportion of metamorphic clasts high but variable cr and low uniform zr abundances complementary framework mode and bulk geochemistry indicate that the sandstones were derived from a dissected continental magmatic arc of predominantly acidic composition similar to average upper continental crust but with an admixture of minor intermediate basic material flysch deposition took place in a fore arc setting the presence of an arc to the south of cornwall during the devonian implies that there was subduction at the margin of the gramscatho basin whose ultimate closure was accommodated by the northward stacking of flysch ophiolite nappes

sandstone composition and provenance of the rotliegend of the ne german basin abstract the ne german basin contains an approximately 2 5 km thick rotliegend sedimentary section subdivided into 4 formations these were deposited following the cessation of the late carboniferous early permian volcanic episode and a ca 20 ma period of erosion and non deposition initial deposition was confined to two areas but with increasing thermal subsidence the basin extended to the south petrographic 190 sandstones and geochemical 48 sandstones and mudstones analyses suggested that the sands are quartz rich and are derived largely from cratonic or recycled sources volcanic and sedimentary rock fragments form most of the labile grains the succession was deposited in a relatively stable tectonic environment with sediment input derived largely from the lower and upper palaeozoic strata of the variscan hinterland and the upper carboniferous and lower permian volcanics volcanic input increases with younger stratigraphic units this is interpreted as resulting from the unroofing of a more basic source

grain size control of mineralogy and geochemistry in modern river sediment new guinea collision papua new guinea the new guinea collision includes diverse sediment source areas associated with arc continent collision to the west of the solomon sea triple junction and with subduction of oceanic crust to the southeast and northeast of the triple junction twenty seven sediment suites each comprising up to seven gravel sand and mud samples from the same locality were analysed to determine mineralogical and geochemical variation with changing grain size this paper deals primarily with the mineralogical variation compositional variation from coarse to fine grained fractions is generally 50 of each variable s abundance with many variables showing greater than 100 variation in contrast variation due to analytical error is generally less than 10 between year variation generally ranges from 15 to 25 and downstream variation is generally less than 50 petrographic results indicate that sediment composition is fundamentally dependent on grain size the principal control on sediment composition is mechanical weathering of rock fragments and compositional sorting of the constituent mineral phases while the gazzi dickinson method for point counting sediment reduces modal variability and in most cases provides robust provenance discrimination it is unsuitable for discerning faint source rock signatures often revealed by grain size dependent compositional variation only the upper plate magmatic arc provenance signature is evident from recalculated modal and geochemical data and that signature does not reflect the modern upper plate magmatic arc detailed petrographic analysis of grain types as opposed to recalculated modal or geochemical data is required to elucidate both upper and lower plate provenances and discriminate between ancient and contemporary arc provenances

provenance of cretaceous synorogenic sandstones in the eastern alps constraints from framework petrography heavy mineral analysis and mineral chemistry abstract the detrital components of cretaceous sedimentary rocks in the northern calcareous alps reflect the early alpine geodynamic evolution of the austroalpine microplate two contrasting source areas are distinguished on the base of light and heavy mineral analysis the first source area is located at the southeastern margin of the austroalpine and is composed of palaeozoic sediments and metamorphic rocks mesozoic carbonate rocks and ultrabasic rocks derived from the suture zone of the vardar meliata ocean the second source area is located in the northwest in a lower austroalpine position near the transpressive plate margin that juxtaposes austroalpine and penninic units this source area comprises palaeozoic low grade metamorphic rocks including high pressure hp rocks late palaeozoic meta sediments mesozoic carbonate rocks and ultrabasic rocks from obducted slices of penninic oceanic crust chemical analyses of detrital white mica amphibole and garnet support the discrimination between the two source areas tourmaline chemistry calls for a significant amount of metasedimentary rocks in the source area granitoid rocks and high grade metamorphic rocks are rare blue amphibole phengite and chloritoid composition suggest the erosion of lower blueschist facies rocks in the northwestern source area we suggest a modified model of austroalpine valanginian to coniacian tectono sedimentary evolution which is based on 1 an onset of subduction of the penninic ocean no earlier than late cretaceous 2 deposition of the analyzed sedimentary rocks in piggyback basins and 3 a reconstruction of provenance as proposed in this study

petrography and major element geochemistry of the permo triassic sandstones central india implications for provenance in an intracratonic pull apart basin abstract detrital mode composition of feldspars and heavy minerals and major element chemistry of sandstones from the permo triassic succession in the intracratonic satpura gondwana basin central india have been used to investigate provenance the talchir formation the lowermost unit of the succession comprises glacio marine and glacio fluvial deposits the rest of the succession base to top comprising the barakar motur bijori pachmarhi and denwa formations largely represent variety of fluvial depositional systems with minor fluvio deltaic and fluvio lacustrine sedimentation under a variety of climatic conditions including cold warm arid sub humid and semi arid qfl compositions of the sandstones indicate a predominantly continental block provenance and stable cratonic to fault bounded basement uplift tectonic setting compositional maturity of sandstones gradually increases upwards from the early permian talchir to the middle triassic denwa but is punctuated by a sharp peak of increased maturity in the barakar sandstones this temporal change in maturity was primarily controlled by temporal variation in fault induced basement uplift in the craton and was also influenced by climatic factors plots of different quartz types suggest plutonic source rocks for the talchir sandstones and medium to high rank metamorphic plus plutonic source rocks for the younger sandstones composition of alkali feldspars in the permo triassic sandstones and in different precambrian rocks suggests sediment derivation from felsic igneous and metasedimentary rocks compositions of plagioclase in the talchir and bijori sandstones are comparable with those of granite acid volcanic and metasedimentary rocks of the precambrian basement suggesting the latter as possible source rare presence of high k plagioclase in the talchir sandstones however indicates minor contribution from volcanic source rock exclusively plagioclase bearing metasedimentary rock tonalite gneiss and mafic rocks are the probable sources of plagioclase in the upper denwa sandstones quartz rich nature of the sandstones predominance of k feldspar over plagioclase and albite rich character of plagioclase in the sandstones is consistent with deposition in an intracratonic pull apart basin like the satpura gondwana basin composition of garnet and its comparison with that from the precambrian basement rocks suggests mica schist and amphibolite as possible sources predominance of dravite variety of tourmaline in the permian sandstones suggests sediment supply from metasedimentary rocks presence of both dravite and schorl variety of tourmaline in subequal amount in the triassic sandstones indicates sediment derivation from granitic and metasedimentary rocks however schorl bearing rocks are absent in the basement complex of the study area a cn k plot suggests granites acid volcanic rock and meta sediments of the basement as possible sources of the talchir sandstones and metasedimentary rocks for the barakar to pachmarhi sandstones the denwa sandstones were possibly derived from k feldspar free plagioclase bearing metasediments mafic rocks and tonalite gneiss chemical index of alteration cia values suggest low intensity source rock weathering for the talchir sandstones and higher intensity source rock weathering for the others various bivariate plots of major oxides composition of the sandstones suggest passive to active continental margin setting and even arc tectonic setting for a few samples

detrital modes of the pyeongan supergroup late carboniferous early triassic sandstones in the samcheog coalfield korea implications for provenance and tectonic setting abstract medium to coarse sandstones of the carboniferous to early triassic pyeongan supergroup in the samcheog coalfield korea were studied to infer the provenance and tectonic settings of the source areas sandstone detrital modes change upwards stratigraphically sandstone types from the manhang to dosagog formations low to middle in the sequence are quartzarenite and sublitharenite to litharenite whereas sandstones of the gohan and donggo formations high in the sequence are feldspathic litharenite and arkose respectively using various ternary diagrams the provenance of the manhang to gohan formations is suggested to be a recycled orogen setting some gohan formation sandstones plot within the arc related setting field and the donggo formation sandstones plot within both continental block and recycled orogen fields results of quartz grain petrography are consistent with those of detrital modes quartz in sandstones of all units except the donggo formation indicates derivation from low rank metamorphic sources quartz in donggo sandstones was derived from medium to high rank metamorphic and plutonic source rocks considering the sandstone composition and palaeocurrent data the pyeongan supergroup probably was deposited in a molasse foreland basin and was derived from a synbasinal orogenic belt probably the akiyoshi orogen located in southwest japan

miocene sandstone provenance relations in the gulf of suez insights into synrift unroofing and uplift history time compositional relations inferred from point counts of 46 upper oligocene to middle miocene syn rift sandstones from gulf of suez outcrops are used to further constrain the uplift and unroofing history of this neogene continental rift although earliest rifting began by approximately 24 ma as evidenced by minor basaltic volcanism the main phase of crustal extension tectonic subsidence of the axial trough and rift margin uplift began approximately 19 ma oligocene and basal miocene nukhul formation sandstones are dominated by monocrystalline quartz and clasts derived from only the youngest pre rift strata eocene indicating that relief was probably less than 200 m until 20 ma the lower miocene rudeis formation records both major subsidence in the axial trough and peak unroofing of the pre rift sedimentary sequence from 19 16 ma middle miocene sandstones derived from the kareem and belayim formations are increasingly dominated by crystalline basement derived detritus recording rapid increase in rift margin relief after approximately 14 ma diachronism in the first appearance of unroofed basement detritus across the rift indicates uplift of the western margin may have preceded that of the eastern margin by as much as 2 m y once rapid uplift began between about 20 17 ma unroofing of a maximum of 1000 m of the pre rift strata occurred in less than 2 m y