u pb zircon age for a tuff in the campbell group griqualand west sequence south africa implications for early proterozoic rock accumulation rates an ion microprobe u pb age of 2552 11 ma has been obtained on zircon separated from a regional banded tuff horizon in the nauga formation beukes 1980b upper campbell group griqualand west sequence south africa this age permits time constraints to be placed on lithologically correlated units within the adjacent transvaal sequence and correlations to be made with the further removed hamersley group in australia calculated rock accumulation rates of 2 to 4 m m y for these strata of mainly shale and banded iron formation suggest that sedimentation rates were significantly slower in the late archean early proterozoic than is generally assumed

the kinematic and metamorphic history of the sgurr beag thrust ross shire nw scotland abstract this paper presents a field and microstructural study of a caledonian amphibolite facies shear zone within the moine rocks of northern scotland the shear zone the sgurr beag thrust is an important tectonic break within the moine nappe of ross shire and is the structurally highest and oldest of the foreland propagating thrust system the youngest and lowest of which marks the caledonian front in britain microstructures and quartz c axis analysis show that fabrics formed during nappe emplacement were thoroughly recrystallised before or during peak caledonian metamorphic conditions one segment of the shear zone was reactivated as a north directed thrust with retrograde reworking of annealed metamorphic textures quartz rich mylonites from the reactivated zone display asymmetric or single girdle quartz c axis fabrics consistent with north directed overthrust shear except within and immediately beneath an allochthonous orthogneiss sheet of archaean basement here quartz c axis fabrics have orthorhombic symmetry implying that the orthogneiss unit and the thin smear of psammitic mylonites accreted to its base extended coaxially as a rigid sheet while the softer quartz rich mylonites of the enclosing moine accommodated the late non coaxial strain the thrust zone was probably reactivated within the old footwall and by ductile extension of the hanging wall along localised zones of intense non coaxial strain this conclusion emphasises the complexity and longevity of caledonian ductile deformation

evaluation of environmental fate and sinks of pcdd fs during specific extreme weather events in taiwan abstract polychlorinated dibenzo p dioxins pcdds and polychlorinated dibenzofurans pcdfs are persistent organic pollutants pops that are formed and released unintentionally from anthropogenic sources the high persistence of pcdd fs results in the concentrations of these contaminants in environment decreasing only very slowly two transport pathways air and water carry pcdd fs into all regions of the world recently more frequent extreme weather events such as storms and floods have been projected to occur as a result of global warming extreme weather events have a documented impact on the remobilization and subsequent bioavailability of pops in this study three specific episodes namely winter monsoon southeast biomass burning and tropical cyclone typhoon events which influence the environmental fate and transport of pcdd fs in taiwan were evaluated based on a climate change scenario during the winter northeast monsoon period the temperature and relative humidity observed in northern taiwan decreases sharply during this time the quantity of pcdd fs adsorbed onto suspended particles as observed at background sites was found to increase from 300 127 to 630 115 pg i teq g tsp 1 which is even higher than that measured in taipei city 438 80 pg i teq g tsp 1 hence the winter monsoon not only brings cold air but also transports air pollutants and dust over long distances from mainland china to taiwan during the 2010 southeast asia biomass burning events 2010 3 22 3 28 the level of atmospheric pcdd fs were measured in central taiwan mt lulin and in the source region of northern thailand chiang mai this revealed that the variations in atmospheric pcdd f concentrations at these two sites followed a similar pattern on 25 march 2010 the atmospheric pcdd f concentration increased dramatically from 1 43 to 6 09 fg i teq m 3 at mt lulin and from 7 64 to 12 1 fg i teq m 3 in northern thailand however the atmospheric pcdd f concentration decreased dramatically 1 day after the biomass burning event based on the measurements from a dated sediment core collected at a reservoir in northern taiwan the sharp increases in input fluxes of pcdd fs and mineral derived elements levels in 1990 20 ng i teq m 2 year 1 2001 17 ng i teq m 2 year 1 2004 16 ng i teq m 2 year 1 and 2005 15 ng i teq m 2 year 1 seem to be a result of a deep turbid layer formed upstream due to landslides and or mud flows during the typhoon season this finding demonstrates the effect of typhoon events on the long term remobilization of pcdd fs as well as supporting the hypothesis that such events would have the potential to remobilize pollutants that have been deposited previously

early curvilinear fold structures and strain in the moine of the glen garry region inverness shire four regional deformation episodes d1 d4 are recognized in the moine rocks loch eil and glenfinnan divisions of the glen garry area inverness shire nw scotland these episodes fall into two groups early sub recumbent d1 d2 structures and later upright d3 d4 structures d2 structures occur on all scales and appear in a regional sense to be more important than the d1 structures the d1 d2 structures are only preserved in their original disposition where subsequent upright d3 reworking was minimal i e in the region to the e of the loch quoich line and in low strain augen developed in d3 hinge zones to the w of this structure the f2 folds are intensely curvilinear and at many localities f2 hinges lie approximately parallel to the n s trending extension lineation examination of these structures in three dimensions and application of the sanderson 1973 model provides information on the nature and orientation of the regional d2 strain ellipsoid in this part of the moine the d2 xy plane is sub horizontal with the x direction trending approximately n s this is markedly different in orientation from the d3 ellipsoid in this region which being of post glen dessary syenite 456 ma age is demonstrably caledonian the d2 linear fabrics suggest that the direction of tectonic transport was s to n or n to s markedly different from the generally accepted wnw directed movement attributed to caledonian orogenesis these findings are consistent with the proposal that the loch quoich line represents an eastern limit of intense caledonian d3 reworking and that the d1 d2 structures are of precambrian age

structural dating of a precambrian pegmatite in moine rocks of northern scotland and its bearing on the status of the morarian orogeny a cross cutting pegmatite emplaced into low grade non migmatitic proterozoic moine metasediments on the western sea board of inverness shire scotland gives rb sr muscovite ages of 746 776 ma which are interpreted as minimum estimates for the age of formation of the pegmatite intrusion followed at least one phase of folding and schistosity production in the country rocks and an early phase of syn kinematic garnet growth correlated with the regional d 2 tectono metamorphic event the pegmatite was folded and suffered considerable grain size reduction under metamorphic conditions during the regional d 3 deformation episode the dilational character and low grade context of the pegmatite show that it was not a product of melting in place during metamorphism of the adjacent moine schists its lack of initial syn kinematic crystallization textures and fabrics together with the absence of evidence that might relate its emplacement to any regional phase of compressive ductile deformation would be compatible with a considerable time lapse between its intrusion and the earlier deformation and metamorphism of the host rocks we have however no direct evidence for the extent of this interval the relationship of the pegmatite to the earlier deformation and metamorphism of the host rocks provides clear evidence for substantial precambrian orogenic activity but the age of this activity whether 9morarian9 and or 9grenvillian9 remains a matter of interpretation

comment on sr nd isotope composition and clay mineral assemblages in eolian dust from the central philippine sea over the last 600 kyr implications for the transport mechanism of asian dust by seo et al against xu et al 2016 who argued that east asian desert ead dust that traveled on east asian winter monsoon winds dominates over central asian desert cad dust in the philippine sea with presentation of additional data we reconfirm seo et al s 2014 conclusion that cad dust carried on the prevailing westerlies and trade winds dominates over ead dust in overall dust budget of the central philippine sea the relative contribution of dust from eads and cads using clay mineral composition should be evaluated with elimination of mineralogical contribution from the volcanic end member which is enriched in kaolinite and overestimate the contribution of ead dust

discussion of suitable chemical weathering proxies in sediments by comparing the dissolution rates of minerals in different rocks abstractin studies of paleoclimate change variations in major and minor elements are often used as proxies for chemical weathering in soil or lake sediments to prove the suitability of chemical weathering proxies and further discuss the impact of mineral dissolution on element migrations various parent rocks in taiwan were chosen to react with sulfuric acid for discussing mineral dissolution rankings and element leaching during chemical weathering processes the parent rocks include granite andesite actinolite schist slate quartz sandstone calcium sandstone and mudstone experimental results show that dissolution rates are mainly controlled by mineral structures and the chemical compositions of rocks the ranking of rock dissolution rates is as follows mudstone slate actinolite schist quartz sandstone granite dissolution rates of andesite and calcium sandstone cannot be compared due to secondary minerals being produced in experiments moreover the dissolution sequences of minerals are

late brittle deformation in a caledonian ductile thrust wedge new evidence for gravitational collapse in the moine thrust sheet sutherland scotland abstract in the ductile regions of orogenic wedges late brittle structures formed at shallow crustal depths have received little attention however they are important as they of ten record the final stages in deformational history during uplift and erosion of the orogen in the moine rocks of sutherland late caledonian brittle folds and low angle faults post date ductile structures formed during wnw nw directed thrust movements earlier in the same orogenic event in the western moine nappe the late structures display geometries which indicate that they formed during regionally ese directed extensional movements down the dip of the pre existing regional foliation these late structures are correlated with similar wnw directed extensional low angle faults recognised in the moine thrust zone south of the assynt culmination both are thought to have formed in response to late caledonian gravity induced thinning of the moine thrust wedge and both pre date devonian extension associated with the formation of the west orkney basin along strike changes in the location and sense of extensional movements north and south of the assynt culmination are explained by changes in the pre existing structural geometry of the caledonian ductile thrust nappes within the moine hence earlier deformation patterns are thought to exert important controls over later events in an evolving orogenic wedge

a criterion for identifying asian dust events based on al concentration data collected from northern taiwan between 2002 and early 2007 1 we attempted to identify asian dust ad events between february 2002 and february 2007 in northern taiwan using aerosol al measurements we subsequently used the results to propose a criterion for defining ad events a total of 30 ad events were detected based on al spiking concentrations and these occurred frequently in 2002 and 2006 the dust plumes that were identified occurred between november and april which were concentrated in february march and april there were 35 dusty days which accounted for 1 89 of the whole study period and for 3 75 when considering only november through april the seasonality of atmospheric al is quite evident reaching a maximum in spring and winter and a minimum in summer this pattern is related to the long range transport of ad in the northeasterly monsoon and the cease of ad contributions the efficient removal by heavy rain and effective mixing in summer according to air mass trajectory analysis the primary dust regions are located in and around the gobi desert and loess plateau the geometric mean concentration of the data set excluding the ad cases is 502 ng m 3 with a geometric standard deviation gsd of 2 8 on the basis of our success in identifying the major ad events the geometric mean 2 gsd i e 2800 ng m 3 in our study area is proposed as a straightforward criterion to define the significant ad event as such the statistic based criterion could be applicable for other areas

intrusive metabasite belts within the moine assemblage west of loch ness scotland evidence for metabasite modification by country rock interactions metabasites representing an extensive differentiated sill complex with minor dykes now form two c 10 km wide ne sw belts in western inverness shire a western belt overlapping the quoich line and an eastern belt beside the great glen fault regional evidence and where interpretable rb sr isotope data imply grenvillian emplacement more than one intrusive episode may be represented by contrasting adjacent discordant unfoliated versus concordant foliated bodies although some such contrasts reflect later tectonism despite variations in form size internal homogeneity paragenesis grain size and fabric 120 newly analysed metabasites have much more uniformly tholeiitic chemistry than metabasites in the moine of ross shire or sutherland discriminant analysis nevertheless reveals that the eastern belt is compositionally invariable from ne to sw whereas the western differs between three sub areas studied in detail and shows more numerous evolved compositions a single andesitic rock c 57 sio 2 is the most evolved metabasite so far reported from the moine metabasite country rock interactions during igneous emplacement and or regional metamorphism caused major chemical transfers for example host psammites and granite gneisses gained ca causing hornblende to crystallize metabasites in limestones gained ca mg sr and lost fe ti rb rb y and zr totally suppressing garnet metabasites in pelites lost na enhancing garnet relative to plagioclase metabasites within psammites gained k and rb enhancing biotite and metabasites within granite gneisses gained na k mn rb and sr suppressing epidote overall chemical differences between metabasites with or without biotite epidote and garnet may reflect the same interactions rather than original magmatic variations even the immobile element chemistry of high grade metabasites may be an unreliable tracer of magmatic chemistry unless country rock interactions are allowed for

structural setting and geochronological significance of the west highland granitic gneiss a deformed early granite within proterozoic moine rocks of nw scotland a re investigation of the six major outcrops of granitic gneiss within the glenfinnan and loch eil divisions of the moine has shown that they are a suite of deformed and metamorphosed granite intrusions they record all the tectonic events recognized in their host metasediments while the absence of thermal aureoles suggests that their emplacement was synmetamorphic i e syn d 1 rather than pre d 1 their dominant gneissic fabric is of s 2 age but in low strain augen an earlier s 1 fabric is preserved which is cut by mp 1 leucocratic segregations contemporaneous with but compositionally distinct from those in the pelitic regional migmatites of the moine the deformed granites underwent local mp 2 remelting and have been widely intruded by later caledonian pegmatites the gneiss has a uniformly granitic sensu stricto bulk composition regardless of country rock lithology or location within the glenfinnan and loch eil divisions it has strongly s type chemical affinities being reduced and peraluminous with a high initial 87 sr 86 sr ratio it was probably produced at least in part by partial melting of moine like rocks at depth a published rb sr whole rock isochron of c 1028 ma probably dates intrusion of the ardgour body and confirms the reality of a 9grenvillian9 event in the glenfinnan and loch eil divisions of the moine

the loch quoich line a limit of early palaeozoic crustal reworking in the moine of the northern highlands of scotland the loch quoich line a major structural line at least 60 km in length within the moine of the northern highlands of scotland has hitherto been variously interpreted as a major tectonic dislocation the root zone of a nappe and an unconformity the work reported here was carried out at the type locality of the line and was directed at resolving these ambiguities the lithostratigraphic succession established by sedimentary structures shows that the rocks of the glenfinnan division are older than but are stratigraphically continuous into those of the loch eil division rocks of the loch eil division crop out extensively to the w of the loch quoich line and are not restricted in outcrop to the area e of the line as was previously thought the early d 1 d 2 structures were initially sub horizontal steeply inclined nne trending d 3 structures are weakly developed e of the axial trace of a major fold the beinn beag synform in this area the metasediments remain essentially in their post d 2 gently inclined attitude w of the axial trace of the synform the earlier folds and fabrics were severely reworked into steep attitudes during d 3 producing nne trending zones of 9platy9 rocks which mark regions of severe strain on d 3 fold limbs earlier d 1 d 2 structures are clearly preserved in d 3 hinge zones which mark zones of low d 3 strain it is concluded that the loch quoich line coincides with the axial trace of the beinn beag synform and that it is the eastern limit of severe tectonic reworking probably caledonian over printing early probably precambrian structures recognition of structural and stratigraphic continuity between the glenfinnan and loch eil divisions implies that the loch quoich line cannot be correlated across the great glen fault with the putative unconformity separating the grampian cover and central highland basement divisions in the moine rocks of the central highlands

long range southeastward transport of asian biosmoke pollution signature detected by aerosol potassium in northern taiwan 1 total potassium was determined in aerosol particles between 2002 and early 2007 in northern taiwan 25 02 n 121 31 e biosmoke potassium non sea salt noncrustal was assessed and used as a tracer of biosmoke pollution which essentially represents the combination of coal and biofuel combustion and biomass burning pm10 associated potassium displays a typical seasonality peaking during the winter and waning during the summer the size distribution showed a bimodal pattern peaking at a supermicron size 2 5 5 6 m and at around 1 m demonstrating multiple sources size distribution patterns revealed an evident seasonality indicative of the different domination of natural and biosmoke sources in the two main periods of the northeasterly and summer monsoons respectively the relative contributions of biosmoke and natural sources to the total potassium were estimated to be 50 75 and 25 50 respectively the seasonality of biosmoke potassium is similar to that of total potassium substantial correlations existed between biosmoke potassium and selected trace metals as se pb and mn suggesting that the latter are essentially associated with biosmoke pollution another significant finding is that the seasonal mean concentrations of aerosol potassium between 2002 and early 2007 tend to increase this could primarily be attributed to the increased consumption of coal in china posing an urgent issue relevant to pollution mitigation in china the southward inflow flux of biosmoke potassium to the south of 25 n during the northeasterly monsoon months has been estimated to be 56 79 mg m 2 d 1 which could be applied to the assessment of other biosmoke related species

the late archean to mesoproterozoic major unconformity bounded units of the kaapvaal province of southern africa reply abstract the late archean to mesoproterozoic 3 1 1 4 ga sedimentary and volcanic successions in the kaapvaal province of southern africa previously have been subdivided into numerous lithostratigraphic units that generally were believed to have been deposited in local or regional basins however these lithostratigraphic units are remnants of thirteen unconformity bounded sequences or units 10 3 m thick with composite strike lengths of 250 1100 km and with durations of 10 7 to 10 8 yr all of these units rest somewhere on the crystalline basement the stratotypes but not the full geographic extents of these sequences from the base upward are the dominion group west rand group of the witwatersrand supergroup central rand group of the witwatersrand supergroup klipriviersberg group of the ventersdorp supergroup platberg group of the ventersdorp supergroup pniel group of the ventersdorp supergroup black reef quartzite formation and chuniespoort group of the transvaal supergroup pretoria group of the transvaal supergroup and the interval represented by the dullstroom formation rooiberg group and the loskop formation three or more major unconformity bounded units occur in younger proterozoic rocks in the kaapvaal province but are not definitive of it two occur in the soutpansberg group and one is most of the waterberg group some of these unconformity bounded units are remarkably similar to phanerozoic cratonic and miogeoclinal sequences they are the natural building blocks for reconstructing archean and proterozoic depositional basins plate tectonic events continents and a provincial time scale

an overview of the geology of the transvaal sequence and bushveld complex south africa the late archaean early proterozoic transvaal sequence is preserved within the transvaal kanye and griqualand west basins with the 2050 ma bushveld complex intrusive into the upper portion of the succession within the transvaal basin both transvaal and bushveld rocks are extensively mineralized the former containing large deposits of iron manganese asbestos andalusite gold fluorine lead zinc and tin ores and the latter some of the world s major occurrences of pge chromium and vanadium ores transvaal sedimentation began with thin predominantly clastic sedimentary rocks black reef vryburg formations which grade up into a thick package of carbonate rocks and bif chuniespoort ghaap taupone groups these lithologies reflect a carbonate bif platform sequence which covered much of the kaapvaal craton in reaction to thermal subsidence above ventersdorp aged rift related fault systems an erosional hiatus was followed by deposition of the clastic sedimentary rocks and volcanics of the pretoria postmasburg segwagwa groups within the three basins under largely closed basin conditions an uppermost predominantly volcanic succession rooiberg group loskop formation is restricted to the transvaal basin a common continental rift setting is thought to have controlled pretoria group sedimentation rooiberg volcanism and the intrusion of the mafic rocks of the rustenburg layered suite of the bushveld complex the dipping sheets of the rustenburg magmas cut across the upper pretoria group stratigraphy and lifted up the rooiberg lithologies to form the roof to the complex subsequent granitic rocks of the lebowa and rashoop suites of the bushveld complex intruded both upper rustenburg rocks and the rooiberg felsites

transport of mineral and anthropogenic aerosols during a kosa event over east asia 1 a quantitative appraisal of the formation processes and distribution of mineral aerosols internally mixed with anthropogenic substances is necessary for estimating the aerosol radiative forcing especially over the north pacific region a large scale kosa yellow dust phenomenon associated with the movement of a low pressure system was observed at nagasaki about 1000 km east of the asian continent in the spring of 1996 during the kosa period april 16 17 fine sulfur particles appeared first and after 12 hours a major plume of large mineral particles reached nagasaki which was detected and measured by the single particle analysis with sampling intervals of 2 hours the results demonstrate that asian dust storms are occasionally capable of transporting mineral and anthropogenic particles in separate air masses from the source regions via the marginal seas to the western north pacific we note that it takes a certain time to admix the different air masses containing various types of aerosols along their transport paths from the asian continent to remote marine atmosphere the interactions of mineral particles with anthropogenic substances predominantly take place within the marine boundary layer toward the east over the north pacific

strengthening of paleo typhoon and autumn rainfall in taiwan corresponding to the southern oscillation at late holocene the purpose of this study is to improve prehistoric knowledge of paleo typhoon and winter monsoon activity in the western north pacific after 8 cal ka bp we examine two sediment cores derived from lakes located to the south and north of the ilan plain in northeastern taiwan seasonal and typhoon rainfall data over the past several decades are collected for this study region we also use mineral indicators k rb ratios and grain size to estimate sediment sources intensity of chemical weathering and rainfall intensity the results show that the chemical weathering index k rb ratio of meihua lake indicates the continuing effects of autumn rainfall while coarse grain sizes of dahu lake sediments suggest increased intensity in typhoon rainfall grain size results reveal that increasing el nino southern oscillation intensity in the tropical pacific has intensified the activity of super typhoons in the western north pacific finally we find that frequent activity of super paleo typhoons occurred in taiwan during the la nina like state and the strengthening winter monsoon activity and higher sea surface temperature enhanced plentiful autumn rainfall in el nino like state after comparing our results with the paleo typhoon data in japan and south china we suggest that the tracks of super typhoon are mainly affected by variations in the warm pool and subtropical northwestern pacific high in the western pacific copyright 2012 john wiley sons ltd

the metamorphic environment of the sgurr beag slide a major crustal displacement zone in proterozoic moine rocks of scotland new evidence from the sw northern highlands of scotland establishes the southerly extension of the sgurr beag slide interpretation of changes in the mineralogy of calcsilicate rocks particularly the use of the anorthite content of plagioclase feldspar as an index of metamorphic grade together with consideration of the texture and mineralogy of pelitic rocks suggests that the slide juxtaposes crustal segments of different metamorphic grade and history movement on the slide post dates a major phase of regional metamorphism and two phases of regional deformation of precambrian age was synchronous with a regional fold forming event and regional metamorphism at or before c 467 ma caledonian and was followed by regional folding models of the thermal effects of displacement across syn metamorphic shear zones are investigated with particular reference to the roles of thermal relaxation and levels of shear strain a model based on the development of a ductile syn metamorphic asymmetric shear zone best explains the metamorphic patterns associated with the sgurr beag slide an original low to moderate easterly dip is implied with north westerly upthrusting of the eastern crustal block

asian dust input in the western philippine sea evidence from radiogenic sr and nd isotopes the radiogenic strontium sr and neodymium nd isotope compositions of the detrital fraction of surface and subsurface sediments have been determined to trace sediment provenance and contributions from asian dust off the east coast of luzon islands in the western philippine sea the sr and nd isotope compositions have been very homogenous near the east coast of the luzon islands during the latest quaternary yielding relatively least radiogenic sr sr 87 sr 86 0 70453 to 0 70491 and more radiogenic nd isotope compositions epsilon nd 0 5 3 to 5 5 these isotope compositions are similar to luzon rocks and show that these sediments were mainly derived from the luzon islands in contrast the sr and nd isotope compositions of sediments on the benham rise and in the philippine basin are markedly different in that they are characterized by overall more variable and more radiogenic sr isotope compositions sr 87 sr 86 0 70452 to 0 70723 and less radiogenic nd isotope compositions epsilon nd 0 5 3 to 2 4 the sr isotope composition in the huatung basin is intermediate between those of the east coast of luzon and benham rise but shows the least radiogenic nd isotope compositions the data are consistent with a two end member mixing relationship between luzon volcanic rocks and eolian dust from the asian continent which is characterized by highly radiogenic sr and unradiogenic nd isotope compositions the results show that asian continental dust contributes about 10 50 of the detrital fraction of the sediments on benham rise in the western philippine sea which offers the potentials to reconstruct the climatic evolution of eastern asia from these sediments and compare this information to the records from the central and northern pacific

iron mineralogy characteristics of the desert sediments of the tarim basin and its provenance implications the vast desert area of the tarim basin contains a large amount of loose sediment and consequently it is one of the most important sources of aeolian dust in the mid latitudes of the northern hem