u pb evidence for polymetamorphic history of huronian rocks within the grenville front tectonic zone east of sudbury ontario canada abstract this paper presents u pb geochronological data for zircon titanite monazite apatite allanite and rutile from street township east of sudbury that help unravel two main facets of the geology of the grenville front tectonic zone gftz they document the presence of extensive huronian supergroup magmatic ca 2480 2460 ma and sedimentary rocks inside the gftz and highlight the significance of bimodal magmatism in the genesis of the huronian supergroup the data also provide further insights into the complex orogenic evolution of the gftz showing in particular that amphibolite facies metamorphism migmatization and deformation during grenvillian compression at 995 980 ma overprinted but did not totally erase the memory of earlier metamorphic events at ca 1720 and 1470 ma from the point of view of u pb systematics the results emphasize the nearly ubiquitous state of isotopic disequilibrium in these rocks most of the minerals investigated comprise two or more generations and are generally in a state of partial resetting because of the superimposed effects of younger events the preservation of pre grenvillian ages in titanite and allanite demonstrates that processes related to final grenvillian collision and exhumation occurred at great speed only apatite and to some degree rutile yield ages that are clearly post tectonic thereby reflecting the final stages of exhumation and cooling of the region

geology of the mineralized zone of the wanapitei complex grenville front ontario the wanapitei complex 6 km 2 5 km lying 0 4 km southeast of the grenville front consists of a northwestern zone of gabbro and folded injection breccia and a southeastern layer of intensely folded hornblendeplagioclase gneiss disseminated ni cu sulphides are unevenly distributed in a zone between the injection breccia and the folded gneiss

patterns and processes of shell fragmentation in modern and ancient marine environments shell fragments are important components of many recent and fossil marine benthic ecosystems and can provide crucial information on past and present environmental conditions interpreting such fragments requires integrated knowledge in various fields and the information potential is therefore rarely optimally utilized this paper uses the definition of a fragment as being a piece of shell having less than 90 of its original form it then outlines the potential characteristics pathways and fates that shells and their fragments can have fragmentation is a key factor shaping the shelly part of death assemblages but it is difficult to interpret because it can be broadly caused by ecological biostratinomic or diagenetic processes and also depends on shell strength strength in turn reflects multifunctionality during ontogeny and depends on a complex set of skeletal and taphonomic factors therefore no particular shell parameter clearly determines strength but thickness microstructure type and degree of organic matrix have the strongest influence on pre and post mortality strength size measurements are usually less important for shell strength than thickness although ecologically complex size refuges from predation do exist similarly shell shape sculptural features and specific aperture types in gastropods provide various defence strategies rather than increasing strength per se key ecological factors of fragmentation include predation due to crushing peeling along with mistaken predation selfinflicted damage during predation and burrowing and more physical aspects such as impacts by stones modern studies must consider damage by benthic commercial fisheries or dredging by scientific vessels key biostratinomic factors include transportinduced abrasion littoral zone of surf washed beaches bioerosion and dissolution mainly sublittoral environments diagenetically fragmentation during compaction mainly occurs when shells are in direct contact with one another or with coarser grains taphonomic features e g drillholes have only minor influence a key step in interpreting fragments is to categorize breakage into repaired versus unrepaired diagnostic versus nondiagnostic and severe versus localized damage quantifying the above categories can then provide useful information on breakage patterns and underlying processes understanding the many characteristics of shells and their fragments is a significant interpretive tool in maximizing the information gain in palaeoecological and taphofacies analyses d 2003 elsevier science b v all rights reserved

geology of the east bull lake gabbro anorthosite pluton algoma district ontario the east bull lake pluton a layered gabbro anorthosite intrusion 90 km west of sudbury ontario is in an inward dipping lopolith and is 780 m thick in the centre and elliptical in plan view 13 5 km 3 5 km it intruded archean metavolcanic and metaplutonic rocks of the superior province during the early proterozoic 2480 ma the intrusion consistes of a basal anorthositic unit succeeded by rhythmic layered gabbro troctolite layered gabbro and massive and dendritic gabbro units it is offset by the west northwest striking subvertical folson lake fault south of this fault only anorthosite and massive and dendritic gabbro are exposed north of the fault subsurface lithologies intersected by me boreholes correlate with surface lithologies troctolite the most distinctive marker that can be correlated between boreholes and surface exposures confirms the general attitude and shape of the layers and lopolith chemical composition of the intrusion ranges from high mg tholeiite to calc alkaline high

the nature age and petrogenesis of the cartier batholith northern flank of the sudbury structure ontario canada abstract the cartier batholith exposed about 50 km northwest of sudbury ontario canada is a late archean k rich granitic batholith along with the levack gneiss complex it forms the footwall of the north range of the sudbury igneous complex the cartier batholith dominantly monzogranitic to granodioritic is relatively homogeneous unfoliated and contains k feldspar megacrysts it shows several distinctive chemical features including high concentrations of zr th u and lree and low concentrations of nb ti and hree several discriminants suggest a post orogenic tectonic environment for the batholith this inference is consistent with a u pb age of 2642 1 ma obtained on zircon only slightly younger than the inferred timing of high grade metamorphism of the levack gneiss complex the cartier batholith could have formed as a result of approximately 33 partial melting of the levack gneiss complex

ambiguities in human and elephant interactions stories of bones sand and water from castel di guido italy geoarchaeological and taphonomical studies have been carried out on the sequence and on the faunal remains of castel di guido central italy a middle pleistocene site with acheulean industry and faunas including elephas palaeoloxodon antiquus bos primigenius equus ferus and other taxa investigation focused on remains accumulated on the bottom of a depressed area probably an ephemeral stream channel sometimes acting as a seep the assemblage resulted prevalently from human activity as shown by the selection of the faunas by the thorough fracturing of the bones and by the occurrence of abundant chipped stone industry and bone bifaces it is still a matter of debate whether the animals were hunted or scavenged the present day distribution of the remains does not represent exactly their original configuration as in most sites of this type and age more likely the objects are partly in their original position and partly reworked and lie within a complex palimpsest of several phases of fluvial transport and human activity with the addition of external inputs of reworked bones and artefacts

neoarchean trondhjemitic and tonalitic orthogneisses identified within the northern grenville province in ontario by precise upb dating and petrologic studies abstract integrated field petrologic and geochronological studies reveal the presence of heretofore unrecognized neoarchean trondhjemitic and tonalitic orthogneisses north and northwest of lake nipissing in the northern grenville province of ontario the high al type trondhjemitic orthogneiss termed warren trondhjemite forms several intrusions with a total exposed area of 300 km 2 the tonalitic orthogneiss including the tilden tonalite forms a discontinuous zone of intrusions about 20 km long and up to 1 6 km wide both trondhjemitic and tonalitic orthogneisses are geochemically distinct from paragneiss that forms the country rocks precise u pb zircon and titanite dating of the warren trondhjemite at six locations and of the tilden tonalite at one location indicates that the former was emplaced at 2679 2 ma whereas the latter was intruded at 2669 4 ma a 996 to 975 ma metamorphism shown by the lower intercept ages of concordia plots of all samples caused partial pb loss from primary neoarchean zircons and titanites and also induced new growth of zircons in a local pegmatitic patch and of titanite in orthogneisses intrusive relationships between the orthogneiss and the country rock paragneiss indicate that the paragneiss is also archean in age the orthogneiss and the paragneiss together constitute an archean crustal sequence southeast of the grenville front boundary fault within the ontario segment of the grenville province this archean sequence resembles the pontiac subprovince of the superior province in western quebec in several important ways including the dominance of compositionally similar metasediments comparable depositional ages of the metasediments and contemporaneous granitoid plutonism at about 2680 to 2670 ma differences also exist between the two for example the major granitoids in the pontiac subprovince are generally more k rich

the role of komatiitic and picritic magmatism and s saturation in the formation of ore deposits abstract the introduction of high temperature high magnesium komatiitic and picritic magmas into the earth s upper crust has given rise either directly or indirectly to many of the world s major ore deposits there is a direct association between komatiitic magmatism and kambalda style ni cu pge deposits the link between magma type and mineralization is not as clear cut in the case of the noril sk cu ni pge deposits but nevertheless there is an association between picritic magmatism and ore deposit development komatiitic and or picritic magmatism may also have contributed to the formation of many types of hydrothermal ore deposits recent nd isotope data generated by kent et al 1994 provide strong evidence for the hypothesis proposed by keays in 1983 that the au in archaean au deposits was derived either directly or indirectly from komatiites through the action of metamorphic fluids the importance of komatiitic and picritic magmas in ore forming processes arises from the fact that they are among the few mafic ultramafic magma types that are s undersaturated at the time of magma formation s saturation of magmas leads to marked depletion in the chalcophile metals for example czamanske and moore 1977 estimated that a third of the original cu and ni contents of morb were lost from the magmas due to extraction into magmatic sulphides the depletion in au and the pge is much greater due to their much larger partition coefficients keays and scott 1976 komatiitic and picritic magmas are s undersaturated because they are high temperature magmas produced by large degrees of partial melting of upper mantle sourc regions that were already depleted in s through earlier partial melting events most mafic magmas produced by less than 25 partial melting are s saturated and hence depleted in the ore forming chalcophile elements in contrast komatiitic and picritic magmas have their full complement of chalcophile metals when they do become s saturated they form sulphides that are strongly enriched in ni cu au pge and other strongly chalcophile metals these may accumulate to form ore deposits directly e g magmatic ni cu pge sulphides or be dispersed in komatiitic picritic rocks or their fractionation products making these source rocks for hydrothermal au or vms deposits

u pb baddeleyite ages of the kerns and triangle mountain intrusions nipissing diabase ontario u pb ages have been determined for two diabase intrusions from kerns and hudson townships that are part of the nipissing diabase suite from the proterozoic southern province canada the ages of the kerns and triangle mountain intrusions are 2217 2 4 and 2209 6 3 5 ma respectively based on analysis of primary baddeleyite from both intrusions together with a published u pb age for the castle mine intrusion these data indicate that the nipissing sills were emplaced separately over a time span of 2 8 1 6 ma given by the maximum and minimum overlap of errors on the u pb ages

occupational intensity and environmental changes during the howiesons poort at klipdrift shelter southern cape south africa abstract the howiesons poort characterised by sophisticated lithic technologies and evidence of innovative behaviours was a significant cultural phase in southern africa during marine isotope stage 4 it also coincided with substantial palaeoenvironmental and possible demographic changes in the southern cape of south africa especially with regard to the shifting palaeo coastline off the agulhas bank the newly excavated klipdrift shelter in the southern cape presents a rare opportunity to compare faunal lithic and palaeoenvironmental evidence from a single howiesons poort site along the present day southern coast of south africa here we use faunal data from klipdrift shelter to explore the relationship between occupational intensity subsistence behaviour and environment in the southern cape during the howiesons poort period our results suggest a shift from a mixed terrain browse dominated environment during the earlier howiesons poort to open grasslands in the mid later howiesons poort this environmental shift corresponds to potential changes in occupational intensity or frequency throughout the sequence with evidence of increased occupations associated with grassier environments aspects of the cultural sequence for example raw material procurement strategies may be associated with shifting environmental conditions the faunal evidence suggests links between occupation environment and prey selection at klipdrift this raises interesting questions about the interplay between population density and the environment of the southern cape and its influence on subsistence behaviour during marine isotope stage 4

surface modification on bone trampling versus butchery abstract previous researchers have reported difficulties in distinguishing between surface marks on bone formed by sedimentary abrasion and those inflicted while butchering trampling by large ungulates and humans has been credited with producing pseudocut marks natural alterations to the bone that mimic cultural ones the purposes of this research are 1 to re examine trampling as a taphonomic process and 2 to suggest criteria useful for distinguishing sedimentary abrasion including trampling from butchery macroscopic and microscopic comparison of experimentally trampled bones and those which have had soft tissue removed with a flint tool demonstrate significant differences between the surface modifications produced by the two processes

the difference in chemical composition of the 1962 lava from miyakezima magma reservoir in japan many examples of mixed magmas in banded lavas have been studied another type of mixed magmas or inhomogeneity of magma reservoir found in the 1962 lava flows of miyake zima volcano erupted from fissures is reported

experimental study of cut marks made with rocks unmodified by human flaking and its bearing on claims of 3 4 million year old butchery evidence from dikika ethiopia abstract in order to assess further the recent claims of 3 4 ma butchery marks on two fossil bones from the site of dikika ethiopia we broadened the actualistic interpretive zooarchaeological framework by conducting butchery experiments that utilized naive butchers and rocks unmodified by human flaking to deflesh chicken and sheep long limb bones it is claimed that the purported dikika cut marks present their unexpectedly atypical morphologies because they were produced by early hominins utilizing just such rocks the composition of the cut mark sample produced in our experiments is quite dissimilar to the sample of linear bone surface modifications preserved on the dikika fossils this finding substantiates and expands our earlier conclusion that considering the morphologies and patterns of the dikika bone surface modifications and the inferred coarse grained depositional context of the fossils on which they occur the dikika bone damage was caused incidentally by the movement of the fossils on and or within their depositional substrate s and not by early hominin butchery thus contrary to initial claims the dikika evidence does not warrant a major shift in our understanding of early hominin behavioral evolution with regard to carcass foraging and meat eating

explaining the klasies pattern kua ethnoarchaeology the die kelders middle stone age archaeofauna long bone fragmentation and carnivore ravaging abstract the caves at klasies river mouth krm in the southern cape province south africa continue to play an important role in the study of human evolution and debates about the origins of modern humans as with most palaeolithic sites the behavioural interpretations offered for the middle stone age msa inhabitants of the krm caves are based in large part on the interpretation of fragmentary faunal remains from the main site or caves 1 1a 1b and 2 excavated in 1967 68 by singer wymer 1982 using zooarchaeological patterns detected in ethnoarchaeological data collected among kua foragers of the eastern kalahari central district botswana as well as in data collected from die kelders cave 1 layer 10 south africa we offer an alternative explanation for a provocative pattern of skeletal part representation discovered in the krm msa archaeofauna over 20 years ago by richard klein 1976 the klasies pattern is characterized by the underrepresentation of large bovid upper limb elements relative to more anatomically complete small bovids to date the pattern has been interpreted in three different ways each with strikingly different implications for middle stone age msa middle palaeolithic mp human behaviour understanding the nature of the pattern is not only important for reconstructing msa human behaviour at krm but it is also important for understanding how the conduct of zooarchaeological analyses can profoundly influence our reconstructions of the course of human behavioural evolution the kua ethnoarchaeological data and experimental case studies unambiguously connect to site formation histories to zooarchaeological patterns at die kelders cave 1 layer 10 the ethnoarchaeological expectations are expressed archaeologically in a context analytically relevant to krm overall by joining the kua and the die kelders data we show how uniformitarian actualistic approaches can be productively employed in zooarchaeological interpretation the klasies pattern is likely to be an artefact of a widespread taphonomic sequence followed by a particular style of analysis employed for practical reasons by many zooarchaeologists we suggest that the situation is common and likely to be seriously distorting inferences about many archaeofaunas around the world more generally we show how uniformitarian studies offer a coherent framework for developing methods and generating data useful in making behavioural inferences from faunal remains rather than a human behavioural signal in the krm archaeofauna the klasies pattern has more to do with the methods of zooarchaeology than with the behaviour of ancient people

terminology for layered intrusions the terminology of igneous cumulates was originally formulated on the concept that the rocks were concentrations of minerals accumulated by crystal settling it is now well established for several major intrusions that plagioclase that had been typed as cumulus should in fact have floated in its parental magmatic liquid nevertheless the terminology has been valuable in the classification of the rocks of these and other intrusions and it has been useful in certain aspects of their genetic interpretation the name cumulate is therefore redefined so that crystal settling is a possible but not essential process in the origins of the rocks to which it is applied the overall nomenclature of layered intrusions is then reviewed and definitions of names are refined and systematized to clarify their applications careful distinction is made between descriptive and genetic names a cumulate is defined as an igneous rock characterized by a framework of touching mineral crystals and grains that evidently were concentrated through fractional crystallization of their parental magmatic liquids a layer is a sheetlike unit of cumulate that is a distinctive entity in its compositional and or textural features a lamina is a thin 2 5 cm sharply defined layer igneous lamination is a general name for planar structure that is pervasive through cumulates on the scale of their grain size layering is the overall structure and fabric manifest through combinations of layers laminae and lamination the difference between layers and layering is essentially the difference between individuals and a population and the terms that describe one are not necessarily appropriate to the description of the other but the fundamental variants of all of layering lamination grading in layers and layer contacts can essentially be described by one or more of the four modifiers grain size modal textural and cryptic where the last refers to cumulus miner al compositions a system for subdividing layered intrusions is proposed in which distinction is made between general divisions ranked as series zones and subzones and prominent units that are called groups members rhythmic units and cyclic units applications to the skaergaard bushveld muskox stillwater and other intrusions are briefly described

magma plumbing system of the 2000 eruption of miyakejima volcano japan during the 2000 eruption at miyakejima volcano two magmas with different compositions erupted successively from different craters magma erupted as spatter from the submarine craters on 27 june is aphyric basaltic andesite 5 vol phenocrysts 51 4 52 2 wt sio2 whereas magma issued as volcanic bombs from the summit caldera on 18 august is plagioclase phyric basalt 20 vol phenocrysts 50 8 51 3 wt sio2 the submarine spatter contains two types of crystal clots a type and a type andesitic type the phenocryst assemblages plagioclase pyroxenes and magnetite and compositions of clinopyroxene in these clots are nearly the same but only a type clots contain ca poor plagioclase an 70 we consider that the a type clots could have crystallized from a more differentiated andesitic magma than the a type clots because feo mgo is not strongly influenced during shallow andesitic differentiation the summit bombs contain only b type basaltic type crystal clots of ca rich plagioclase olivine and clinopyroxene the a type and b type clots have often coexisted in miyakejima lavas of the period 1469 1983 suggesting that the magma storage system consists of independent batches of andesitic and basaltic magmas according to the temporal variations of mineral compositions in crystal clots the andesitic magma became less evolved and the basaltic magma more evolved over the past 500 years we conclude that gradually differentiating basaltic magma has been repeatedly injected into the shallower andesitic magma over this period causing the andesitic magma to become less evolved with time the mineral chemistries in crystal clots of the submarine spatter and 18 august summit bombs of the 2000 eruption fall on the evolution trends of the a type and b type clots respectively suggesting that the shallow andesitic and deeper basaltic magmas existing since 1469 had successively erupted from different craters the 2000 summit collapse occurred due to drainage of the andesitic magma from the shallower chamber as the collapse occurred it may have caused disruption of crustal cumulates which then contaminated the ascending deeper basalt thus porphyritic basaltic magma could erupt alone without mixing with the andesitic magma from the summit caldera the historical magma plumbing system of miyakejima was probably destroyed during the 2000 eruption and a new one may now form

albitization at 1700 2 ma in the sudbury wanapitei lake area ontario implications for deep seated alkalic magmatism in the southern province u pb geochronology of hydrothermal monazite in albitized rocks from two gold deposits east of the sudbury complex indicates that albitization in the sudbury wanapitei lake area occurred at 1700 2 ma and was coeval with a period of granitic plutonism in the southern structural province between 1750 and 1700 ma a variety of rare earth element ree minerals such as two generations of hydrothermal monazite bastnasite synchysite and gadolinite were identified in the albitized huronian sediments in the espanola sudbury wanapitei lake areas the presence of these ree minerals the extraordinary light rare earth element enrichment in rocks from the sheppard gold property east of the sudbury igneous complex and the elevated ree concentrations in some albitized rocks suggests that sodium rich fluids may have been generated by carbonatitic or alkalic intrusions at depth gold mineralization occurs in rocks that have been altered by at least two different types of fluids 1 peralkaline na ree bearing a

the geochemistry and petrogenesis of the agnew intrusion canada a product of s undersaturated high al and low ti tholeiitic magmas

geoarchaeological investigation of occupation deposits in blombos cave in south africa indicate changes in site use and settlement dynamics in the southern cape during mis 5b 4

a petrochemical study of calcic amphiboles from the east bull lake anorthosite gabbro layered complex district of algoma ontario calcic amphiboles are ubiquitous in the east bull lake anorthosite gabbro complex northeastern ontario the mode of occurrence suggests the amphiboles replaced clinopyroxene throughout the stratigraphic levels of the pluton but they are also prolific in the top younger units three types of amphiboles namely 1 tremolite actinolite 2 actinolitic hornblende and 3 hornblende were identified the composition of the amphiboles shows that they define a continuous series without any obvious compositional miscibility gap the analyses further indicated that the amphiboles evolved from actinolite to hornblende through coupled substitution involving edenite and tschermakite end members among the three coexisting amphiboles chlorine is concentrated in hornblende this is due to preferential location of hornblende along grain boundaries and or its favourable structure

identifying grinding scoring and rubbing use wear on experimental ochre pieces ochre pieces were used experimentally for a variety of grinding scoring and rubbing activities to record and compare the use wear markings that each activity creates on the ochre piece ochre that is ground on coarse or fine grained slabs develops parallel striations that cover the surface of the piece the striations have unfrayed ends grinding is the only activity that results in significant changes to the surface shape of the ochre producing a plane when ochre is scored either to create a deliberate design or to produce powder the grooves that form often do not reach all the edges of the used surface and they regularly have frayed terminations this demonstrates that the incisions were created by multiple scoring strokes when ochre is scored to manufacture ochre powder the incisions that are generated are parallel groups of grooves with erratically oriented grooves as well bone and wooden tools are soft and they therefore do not generally create obvious incisions on ochre pieces grooves created through grinding on a slab or scoring with a stone tool have microstriations within them and they show a range of profile shapes the most common use wear from rubbing ochre on animal hide human skin human hair and wood is smoothing edge rounding and polish although incisions and microstriations also occur occasionally residues are often left on an ochre piece after rubbing or scoring with organic materials the comparative collection of macro and microscopic use wear marks from experimentally ground scored and rubbed ochre is useful as an aid to classifying archaeological collections of ochre

controls on the formation of contact type platinum group element mineralization in the east bull lake intrusion the east bull lake intrusion is the type example of a series of 2 48 to 2 49 ga layered mafic intrusions that developed within the rifted southern margin of the superior craton central ontario the east bull lake intrusion contains contact type pge mineralization e g strata bound pge rich disseminated sulfide mineralization occurring within 200 to 300 m of the contact with footwall and sidewall units although the mineralization locally occurs in massive plagioclase cumulates anorthosite zone most of the sulfides are concentrated within an underlying heterolithic inclusion rich unit inclusion bearing zone that grades into an intrusive breccia disseminated sulfides also occur in fine grained gabbroic veins within brecciated footwall rocks border zone geochemical characteristics of the contact type sulfide mineralization and its host rocks include 1 high average pd abundances throughout the east bull lake intrusion including an average of ca 200 ppb in the lower series 2 low average s contents typically contact type pge mineralization in the east bull lake intrusion reflects flow enhanced gravitational settling of a cu rich sulfide liquid followed by local fractionation of ni rich monosulfide solid solution to produce minor amounts of cu and pt rich residual sulfide liquid most of the observed compositional variation in the sulfides can be modeled using variable silicate liquid sulfide liquid mass ratios field and geochemical observations suggest that the parental magmas to the mineralized parts of the east bull lake intrusion were s saturated and pge rich at the time of their emplacement these fertile parent magmas most likely originated as buoyant feldspathic residual magmas that escaped from a deeper more primitive subchamber although first described from the east bull lake intrusion contact type pge mineralization is now recognized in all of the major east bull lake suite intrusions similar styles of magmatic sulfide mineralization are developed in the contact environments of the bushveld igneous complex platreef deposits and the duluth complex minnesota e g dunka road deposit these contact type deposits are part of the family of basal accumulation magmatic sulfide deposits the economics of low sulfide tenor contact type pge cu ni mineralization such as that developed in the east bull lake intrusion will be most favorable in systems in which 1 the parent magmas possessed high initial pge tenors and reached s saturation prior to emplacement 2 the parent magmas experienced vigorous convection in the early stages of chamber development and 3 segregated sulfide was not diluted by coprecipitating silicate minerals a scenario that is most likely to occur in feldspathic magmas in which plagioclase is the principal high temperature liquidus mineral

fluorine and chlorine contents in the lavas and ejecta of the 1986 eruption of izu oshima volcano abstract fluorine and chlorine in 61 rock samples effused by the 1986 eruption of izu oshima volcano were determined to make clear the behavior of volatiles in the magma their f cl variation patterns differ from each other according to the features of the eruption the rocks erupted from the central cone crater a group have very uniform f contents 82 90 g g while cl contents are variable 200 300 g g due to selective degassing of cl after effusion the lavas and ejecta of fissure eruptions on the caldera floor b group have distinctly higher f 92 136 g g and cl 290 400 g g contents than the a group rocks with larger variations strong correlations are seen among their f cl and sio 2 contents these facts can be explained by separation of volatile free and silica poor minerals from the magma forming the a group rocks the products of fissure eruptions on the outer slope of the somma c group have intermediate f 70 126 g g and cl 240 390 g g contents between those of the a and b group but their variations are as large as the b group rocks contrary to the b group samples no correlations are seen among f sio 2 or cl sio 2 only f cl correlation is significant this indicates that the loss of volatiles during magma migration is predominant andesitic to dacitic pumices ejected from the b craters generally have high f contents 148 179 g g but they can be subdivided into two classes according to the cl content the high cl samples 490 560 g g might be derived from the a magma by strong crystallization fractionation on the other hand the low cl samples 40 160 g g must have another origin e g the basement rocks

experiments in taphonomy abstract several long term taphonomic experiments are described with the aim of providing comparative data with which to interpret palaeontological and archaeological sites the study of taphonomy is an adjunct to site interpretation especially the reconstruction of palaeoecology and an understanding of taphonomic processes can only come about through actualistic and laboratory analyses experiments described include the overton down earthworks 32 year old buried bone trampled bone from draycott 17 years old weathered amphibian bone also from draycott 16 years old surface weathered bone from arabia following 10 years exposure bone dispersal weathering burial burning and scavenging in rhulen wales with many skeletons ranging from 1 to 20 years old and finally a series of laboratory experiments set up to test particular processes these included earthworm activity abrasion breakage and predation on small mammals two examples are given at the end to show how the effects of these processes can be identified in the past and how their identification can help to resolve particular issues in two palaeontological sites these are the middle pleistocene deposits at westbury sub mendip somerset and middle miocene deposits at pasalar turkey

middle stone age bone tools from the howiesons poort layers sibudu cave south africa abstract recently discovered bone implements from middle stone age msa deposits at sibudu cave south africa confirm the existence of a bone tool industry for the howiesons poort hp technocomplex previously an isolated bone point from klasies river provided inconclusive evidence this paper describes three bone tools two points and the end of a polished spatula shaped piece from unequivocal hp layers at sibudu cave with ages greater than 61 ka comparative microscopic and morphometric analysis of the sibudu specimens together with bone tools from southern african middle and later stone age lsa deposits an iron age occupation nineteenth century bushman hunter gatherer toolkits and bone tools used experimentally in a variety of tasks reveals that the sibudu polished piece has use wear reminiscent of that on bones experimentally used to work animal hides a slender point is consistent with a pin or needle like implement while a larger point reminiscent of the single specimen from peers cave parallels large un poisoned bone arrow points from lsa iron age and historical bushman sites additional support for the sibudu point having served as an arrow tip comes from backed lithics in the hp compatible with this use and the recovery of older larger bone and lithic points from blombos cave interpreted as spear heads if the bone point from the hp layers at sibudu cave is substantiated by future discoveries this will push back the origin of bow and bone arrow technology by at least 20 000 years and corroborate arguments in favour of the hypothesis that crucial technological innovations took place during the msa in africa

trampling in coastal sites an experimental study on the effects of shell on bone in coastal sediment abstract faunal remains are often recovered from shelly deposits in coastal sites but little is known about the trampling effects of shell on bone here trampling experiments were conducted to investigate these effects and to describe the types of surface modification that could occur on bone in coastal sediment the results suggest that bone is significantly more likely to exhibit surface modification if trampled in shelly rather than sandy sediment burnt bone is less likely to display trampling modification this is probably because prior to trampling burning exfoliates the cortex making the observation of markings on bone problematic pitting trampling lines and sheen were found to be the most prevalent form of surface modification pitting is a particularly over looked criterion and its presence on archaeological bone suggests that the effects of trampling should be considered in zooarchaeological analyses the pervasiveness of sheen and trampling lines on the experimental bone makes it possible that some incidence of trampling could be mistaken for use wear or intentional polish however the vast majority of trampled bone exhibits sheen which does not resemble anthropogenic specimens and trampling is unlikely to smooth bone fragment edges this experiment demonstrates that modification caused by trampling can generally be differentiated from butchery markings the high percentage of modified trampled bone in the shelly deposits suggests that some shell marks may be mistaken for cut marks if recovered in an archaeological context

on the possible utilization of camelops by early man in north america camelops was a major faunal element in late wisconsin biotic communities over much of north america interpretations of possible human association with camelops are often based on poorly evaluated evidence ideal standards for acceptable evidence are compared here to the actual evidence that has been advanced of 25 fossil assemblages examined 2 might be examples only of geological contemporaneity of humans and camelops 2 might indicate behavioral association of humans and camelops bones and 2 might indicate actual human utilization of camelops killing and or butchering camelops bones interpreted as artifacts are similar to modern specimens affected by noncultural processes

testing heterogeneity in faunal assemblages from archaeological sites tumbling and trampling experiments at the early middle pleistocene site of gesher benot ya aqov israel abstract the current paper reports an experimental case study to test the heterogeneity of faunal assemblages from the early middle pleistocene layers v 5 and v 6 of the gesher benot ya aqov acheulian site israel tumbling and trampling experiments were initiated to gain qualitative insight into processes of bone modification and to assess the timing of the biostratonomic chronology as it was assumed that both mechanisms were responsible for the formation of striations documented on the bone surfaces from the site the tumbling experiments mimicked sediment movement in a calm lacustrine shoreline environment whereas the trampling experiments investigate the role of animal hominin activities in dry muddy and wet environments models for the internal operational sequence of an abrasional process due to uni and multidirectional water movement and of a trampling scenario are presented these models are used for the interpretation of the fauna from gesher benot ya aqov

geoarchaeological investigations at diepkloof rock shelter western cape south africa abstract the sedimentary sequence at diepkloof rock shelter formed through a complex interaction of depositional and post depositional processes and was variously influenced by biogenic geogenic and anthropogenic agents here we present the results of a micromorphological study of the sediments at diepkloof focusing in particular on the numerous anthropogenic inputs and modifications recorded within the sequence by applying the microfacies concept we were able to identify hearth burning and maintenance bedding construction and burning and surface modification by trampling as major processes that contributed to the formation of the site the human activities recorded within the sediments show a marked change throughout the sequence implying a shift in the use of the site over time the present study also provides a context for evaluating other classes of artifacts and data collected from the site

criteria for identifying bone modification by termites in the fossil record three geographically dispersed middle and later stone age cave sites in south africa and a middle stone age cave site in ethiopia share a similar taphonomic signature that includes destruction of bones associated with variable forms of star shaped features clusters of microscopically visible sub parallel striations edge gnawing pits and etching of the bone surface similar traces preserved on plio pleistocene fauna are interpreted by different authors as the possible work of termites or ants considering that ambiguity exists in the interpretation of these traces and that there are no modern examples available for comparison we set out to create a reference collection of bones modified by southern african termites here we present the results of an actualistic experiment conducted with the harvester termite trinervitermes trinervoides sjostedt isoptera termitidae in the sterkfontein valley south africa results show that within six months all bones were approximately half covered with a dark surface residue had an etched surface appearance and recorded boreholes and destruction particularly of less dense elements and epiphyses star shaped marks edge gnawing and clusters of sub parallel striations on the periosteal surface were faint after six months but became clearly visible and more plentiful after 12 months a finding attributed to the termites being more active in austral autumn and spring this result demonstrates the pertinence of insect modification studies to our understanding of regional palaeoenvironment palaeoecology and palaeoclimate this experiment has demonstrated that t trinervoides can destroy bone in all stages of preservation favouring fresh thin cortical and spongy bone with meat and marrow the presence of appreciable quantities of calcium carbonate in termite mounds suggests that termites may be drawn to dolomitic cave sites and the calcium rich bones they contain to satisfy their mineral requirements they therefore have the potential to bias taxonomic and element representation minimum number of individuals and age profiles in a faunal assemblage and may account in part for the patchy preservation of faunal remains including hominins in fossil deposits and or the lack of bone artefacts at some middle stone age cave sites preserving long sequences of occupation

paleoproterozoic boninites in an ophiolite like setting trans hudson orogen canada paleoproterozoic high mg andesites of the birch lake assemblage in the trans hudson orogen display trace element enrichments characteristic of cenozoic boninites occur in an analogous stratigraphic setting and share a metallogenic association with the younger rocks their geochemical compositions indicate substantial prior depletion and a selective reenrichment of the mantle sources consistent with metasomatism by siliceous melts these requirements are best accounted for in an island arc setting and indicate that early extensional stages of subduction zone development have not changed substantially over the past 2000 m y

geology and geochemistry of the east bull lake intrusion district of algoma ontario the east bull lake intrusion is a layered basic lopolith of early aphebian age that intrudes archean basement rocks at the southern margin of the superior province it contains at least two magmatic cycles cumulate olivine plagioclase and clinopyroxene form anorthosite troctolite and olivine gabbro norite in the lower portion of each cycle these rocks are overlain by two pyroxene gabbros norites in which orthopyroxene or pigeonite joins augite and plagioclase as the major cumulate minerals molecular proportion ratio mpr variation diagrams support this interpretation of the petrology of the intrusion and show that the major cumulate rock types represent magmatic liquids formed sequentially by fractionation of the above mentioned cumulate phases small scale phase layering is common in the intrusion size graded layers are absent and cross bedded and igneous lamination features are not common we conclude that this scale of layering formed in a boundary layer along the floor of the intrusion as a

a u pb age for mineralized nipissing diabase gowganda ontario concordant baddeleyite and rutile analyses from mineralized nipissing diabase at gowganda s castle mine yield a u pb age of baddeleyite is a primary phase of the diabase therefore the age dates the magmatic emplacement the genesis of rutile is less certain rutile could have formed during an episode of alteration veining and ag mineralization in which case the u pb age would also date the secondary event and demonstrate that ag mineralization was related to the nipissing magmatism however a primary magmatic origin of the rutile cannot be completely excluded for now thus the u pb age may not constrain the time of ag mineralization further research is needed to clarify this point

blombos cave southern cape south africa preliminary report on the 1992 1999 excavations of the middle stone age levels the later and middle stone age levels at blombos cave bbc were excavated over four field seasons between 1992 and 1999 here we report on the results from the middle stone age msa levels the taphonomy and depositional history of the msa levels is complex due to faulting folding and spalling careful observations during excavation have assisted in understanding some of these taphonomic and site formation processes microstratigraphic analysis currently in progress will add to this information the uppermost msa level the still bay phase contains high densities of bifacial points the fossile directeur of the still bay industry placing the still bay within the msa culture sequence has been problematic in the past because still bay assemblages are rarely found in situ and previous excavations were inadequately recorded however with the regional data discussed in the text the still bay can be securely placed before the howiesons poort dated at 65 70 ka flaked stone makes up the greatest proportion of all artefacts with the highest incidence of retouch and use of fine grained non local materials found in the still bay levels the ochre assemblage is remarkable for the mass of material compared to other msa sites finds uncommon in an msa context are two pieces of ochre from the still bay phase engraved with a geometric design a fragment of deliberately engraved bone also 28 shaped and polished bone tools recovered mainly from a phase just below the still bay blombos cave is the first site where well preserved faunal remains have been recovered in association with the still bay allowing for unique insights into human subsistence behaviour and palaeoenvironmental reconstruction large fish bones marine shells seals and dolphins attest to extensive exploitation of aquatic resources and a wide range of terrestrial animals were hunted and gathered the few human teeth recovered are heavily worn and damaged thus the issue of morphological modernity cannot be addressed the bbc findings are a useful adjunct to findings from other msa coastal sites in the southern cape especially klasies river kr and die kelders cave 1 dk1 uniquely bbc provides insights into human behaviour during a phase of the msa never before studied in detail

the east bull lake intrusive suite remnants of a 2 48 ga large igneous and metallogenic province in the sudbury area of the canadian shield the 2 49 to 2 475 ga intrusions of the east bull lake intrusive suite occur in an east northeast trending discontinuous belt along the presently exposed boundary between the archean superior and the proterozoic southern provinces of the canadian shield near sudbury ontario the east bull lake intrusive suite is part of a regional paleoproterozoic magmatic event extending from 2 49 to 2 44 ga which also includes bimodal volcanic rocks felsic plutons and the regionally extensive hearst and matachewan dike swarms this regional magmatic event is thought to be the result of a mantle plume driven intracontinental rifting event that led to the development of a major basin to the south that was subsequently filled by sedimentary rocks of the huronian supergroup the east bull lake intrusive suite appears to have been emplaced along a major axial rift fault related to this rifting event compelling field and geochemical evidence summarized here indicates that the three largest east bull lake suite intrusions the east bull lake agnew lake and river valley intrusions crystallized from similar low ti high al tholeiitic parent magmas that originated in deeper more basic chambers it is proposed that the primary magmas for the east bull lake suite intrusions were second stage melts derived from a sublithospheric depleted mantle source that had been modified by neoarchean subduction and accretion events most of the petrological characteristics of the east bull lake suite intrusions reflect plagioclase dominated fractional crystallization that generated a pronounced fe enrichment trend in the residual magmas orthopyroxene is the high temperature pyroxene and occurs as a cumulus phase through most of the stratigraphy of each intrusion of the suite local olivine rich cumulates present in all of the major east bull lake suite plutons in some instances appear to be comagmatic with associated plagioclase rich cumulates a distinctive marginal facies comprising brecciated and locally thermally recrystallized and or partially melted footwall rocks is a common feature of the east bull lake suite plutons and indicates that a high energy flow regime existed during the initial stages of emplacement this marginal unit typically grades into a heterolithic inclusion rich gabbronorite that contains erratically distributed mafic autoliths and footwall derived xenoliths chemical contamination of the mineralized matrix of these inclusion bearing rocks can be extreme at a local scale the inclusion rich zone is overlain by a thick interval of undifferentiated plagioclase rich cumulates that locally display spectacular glomerocrystic textures rhythmically and irregularly modally layered leucogabbronorite and gabbronorite make up much of the middle parts of the stratigraphy massive to crudely layered ferrogabbro and ferrosyenite only occur in the uppermost part of the agnew lake intrusion varitextured gabbro and pegmatitic gabbro occur as irregular layers and local veins and pods throughout the stratigraphy the east bull lake suite is currently being explored for contact type platinum group element pge cu ni mineralization that has a clear spatial association with orthopyroxene rich cumulates which are otherwise poorly represented in these intrusions disseminated pge and cu rich sulfide mineralization is concentrated within the inclusion bearing zones but extends upward into overlying plagioclase cumulates and appears to have collected along the lower margins of these intrusions through the combined action of vigorous convection of the resident magma and downward percolation of dense mafic residual liquid the resultant narrow zones of sulfide mineralization were thus derived from a much larger volume of parent magma feeder dikes to the mineralized parts of the intrusions appear to have been saturated in sulfide upon emplacement and had relatively high background pge contents compared to those for other known magmatic pge deposits however the economic potential of the contact type mineralization hinges on the efficacy of the physical concentration process which upgraded the metal content and size of the original sulfide particles inside the magma chambers based on the proposed basal accumulation model the best prospective mineralization is most likely to occur in embayments along the sidewall and floor of the intrusions

cutmarks made by stone tools on bones from olduvai gorge tanzania fossils from olduvai gorge tanzania show cutmarks which establish that hominids were using stone tools on animal tissues during the lower pleistocene in africa we identified cutmarks by elimination of other likely causes of the marks on the bone surfaces for example gnawing or chewing by carnivores or rodents and damage made by tools of excavators or preparators this was achieved by comparing the marks on the fossils with those produced by known causes on modern bones using scanning electron microscopy sem because the fossils occur as part of accumulations of animal remains in relatively undisturbed geological contexts we conclude that there is a functional association between the stone artefacts and bones at these sites rather than an accidental postmortem association1 2

temporal trends in grain size measures on a linear sand dune within aeolian dune systems spatial patterns of grain size variation have been recognized but little has been said about temporal changes increasingly it is becoming clear that linear dunes are associated with bi directional wind regimes which are often seasonal in the namib sand sea where linear dunes are aligned roughly north south winds blow from the west in summer and from the east in winter in response to this regime sand is eroded from the west slopes and deposited on the east slopes in summer and eroded from the east slopes and deposited on the west slopes in winter preliminary evidence from a study of a single namib linear dune reported here confirms that this seasonal aeolian regime induces seasonal responses in some grain size measurements due to the dynamics of sand transport on the dune the characteristics of the sand source immediately upwind of the sample point and the nature of the deposit thus time of sampling is crucial to the results obtained

burned bone in the howieson s poort and post howieson s poort middle stone age deposits at sibudu south africa behavioral and taphonomic implications abstract despite a growing awareness of the wide range of information that can be provided by detailed analyses of burned bone from archaeological contexts such analyses are still relatively uncommon this paper focuses on the behavioral and taphonomic implications of burned bone from the middle stone age msa site of sibudu cave south africa reporting on the analysis of a large sample 377 000 fragments of bone recovered from the howieson s poort hp and post hp msa deposits at the site faunal remains were initially sorted into burning categories based on changes in color microscopic analyses focused on the optical properties of the bone matrix degree of preservation of the bone structure reflectance and fluorescence indicated that the color is a valid indicator of thermally altered bone in the sibudu assemblage the association of burned bone with hearths the intensity of burning damage and the sheer quantity of thermally altered bone suggests that the bone was not burned primarily as a result of natural fires we propose that the high incidence of burned bone primarily reflects two types of site maintenance activities first the discarding of bone into fire as a means of disposing of food waste as also argued by cain 2005 using burned animal bone to look at middle stone age occupation and behavior j archaeol sci 32 873 884 for a smaller sample of material from the post hp and late msa deposits at the site and second the incidental burning of bone on near the surface during the periodic burning of plant based bedding in considering the taphonomic implications of the burned bone we demonstrate that calcined bone is in fact more heavily fragmented than unburnt or moderately burned bone furthermore cortical preservation was negatively correlated with the intensity of burning damage which has implications for the study of surface modifications these results indicate the importance of conducting thorough taphonomic analyses prior to making comparisons between units that show differing degrees or intensities of burning damage

iridium and palladium as discriminants of volcanic exhalative hydrothermal and magmatic nickel sulfide mineralization neutron activation of pd au and ir in samples from 1 economically significant ni sulfide deposits of western australia 2 the host rocks of these deposits 3 hydrothermal and or metasomatic ni sulfide mainly millerite mineralization in peridotite at nullagine western australia 4 hydrothermal replacement volcanic exhalative ni cu sulfide mineralization at sherlock bay western australia and 5 volcanic exhalative sulfides in inter flow sediments at kambalda are used to show that ir and pd can be used to discriminate between the various origins magmatic volcanic exhalative hydrothermal metasomatic and metamorphic ascribed to ni sulfide deposits all the economically significant ni sulfide deposits in western australia are strongly enriched in the precious metals relative to other crustal rocks and have similar pd ni and ir ni ratios to each other these ratios persist regardless of whether the nickel sulfides occur at the base of volcanic ultramafic piles e g kambalda or as centrally disposed interstitial sulfides in intrusive dunite bodies the strong similarities of the pd ir ratios of the ni sulfide ores and of the spinilex textured komatiites which represent ultramafic liquids from which the ni sulfide liquids were derived together with other features of the precious metal geochemistry of the ores and host rocks of the ni sulfide deposits are used to show that the deposits had magmatic origins in contrast the pd ir and ir ni ratios of the hydrothermal and or metasomatic ni sulfide mineralization at nullagine are distinctly different from those of the major ni deposits the former contains high au moderate but variable pd and exceptionally low ir similarly the volcanic exhalative sulfides at kambalda and sherlock bay contain negligible quantities of pd and ir all the ir in both the interflow sediments and the hydrothermal metasomatic mineralization is contributed by the host rocks and not by the sulfides the western australian data together with precious metal data for other examples of hydrothermal ni cu sulfide mineralization strongly suggest that although ni au and pd may be transported in aqueous solution ir cannot hence the relative abundance of ir can be used as a discriminant of magmatic sulfides

the muknal cave near tulum mexico an early holocene funeral site on the yucatan peninsula here we report on an incomplete human skeleton soot patches related to anthropogenic fireplaces and cut marks on the mandible of an extinct peccary from the submerged muknal cave southwest of t

a new element of trampling an experimental application on the level xii faunal record of bolomor cave valencia spain in level xii of bolomor cave valencia spain modifications have been observed on some of the bone fragments that make up the faunal record these alterations consist of small notches located on the oblique fracture angles of some bones the frequency at which these modifications appear in the assemblage has obliged to plan several experimental series to know the process that causes them to be more exact this study aims to verify whether these small chips are the result of trampling for this purpose two experimental series have been developed the first of which has the objective of differentiating between the variables related to the original state of the bone green semi dry and dry and the second is aimed at reproducing the modifications observed in the archaeological set taking into account the data obtained in the previous series following these experiments the appearance of small notches is observed on the oblique fracture angles of some bones in semi dry state these resulting chips are similar to those documented in bolomor cave level xii therefore it is deduced that trampling is the principle cause of these modifications in the bone record this fact has important archaeological implications as the spatial distribution of this modification can provide information about the intrasite movements of the human groups