provenancing and archaeology of roman millstones from the mediterranean area abstract roman rotary grain mills in the mediterranean area are mainly of two styles hourglass shaped pompeian style mills and flatter cylindrical millstones many of these millstones are made of igneous rocks imported to the sites where the mills are found and they may therefore be important indicators of resource procurement and trade if the source of the rock of manufacture can be traced three types of igneous rock were used to make millstones 1 reddish rhyolitic ignimbrite 2 leucite phyric lavas and 3 generally fresh grey vesicular lavas of basic intermediate composition potential source rocks and millstones of all three types of rock were characterized using petrographic examination in thin section and chemical analysis for major and 15 trace elements determined by low dilution fusion wavelength dispersive x ray fluorescence analysis one hundred and forty six millstones and lavas from archaeological contexts were studied and 113 of these were successfully assigned to geological sources sixteen areas of igneous rocks were used by the romans for millstone production these include the basic and intermediate composition grey vesicular lavas of olot northeast spain agde southern france volvic and possibly the le puy area central and southeast france respectively vulture italy etna and monti iblei in sicily pantelleria sardinia ustica the aeolian islands nisyros aegean libya and the middle atlas and rif areas of morocco the red rhyolite was quarried at the village of mulargia in sardinia and the leucite phyric rocks originated on the italian mainland including the quarry of orvieto in umbria there is a wide variation in size and style of millstones from individual production centres and some were exported in unfinished form grey vesicular millstones were traded up to at least 820 km from their sources and fall into four mainly separate distributions in the mediterranean the mulargia rhyolite and the leucitites were moved mainly from north to south were traded further than the grey vesicular rocks and were probably the most desirable types they are found 1350 and 1500 km distant from their sources respectively the millstones were moved mainly by sea perhaps on grain collecting ships on outward voyages from italy to the south and west of the mediterranean

sea level change along the italian coast during the holocene and projections for the future published and new sea level data are used to provide projections of sea level change in italy for the year 2100 by adding new isostatic and tectonic component to the ipcc and rahmstorf projections comparison of the observations from more than 130 sites with different geomorphological and archaeological sea level markers with the predicted sea level curves provides estimates of the vertical tectonic contribution to the relative sea level change the results are based on the most recent anu model for the ice sheets of both hemispheres including an alpine deglaciation model on the basis of the eustatic tectonic and isostatic components to the sea level change projections are provided for marine inundation scenarios for the italian coastal plains for the year 2100 that today are at elevations close to current sea level

vertical movements in ne sicily and its offshore outcome of tectonic uplift during the last 125 ky abstract new data in the coastal area between acquedolci and patti northeastern sicily italy have been collected to calculate vertical tectonic rates in a key sector between the kabilian calabrian and the sicilian maghrebian chain the comparison among marine geology data multibeam and seismic reflection profiles on the continental shelf slope system and the radiocarbon ages on geomorphological markers collected during a coastal survey provided new stratigraphic geomorphological and biological data contributing to the knowledge of the geological evolution of this sector for the last 125 ky this coastal area is framed between two main structural features active during the pleistocene in northern sicily the kabilian calabrian thrust front west of acquedolci and the vulcano tindari fault east of patti the occurrence of these structural features the former compressive the latter transcurrent confirms that the study area is tectonically active and moves vertically in differential mode fault systems separate blocks with different uplift rates both in onland and offshore areas in the gulf of patti the offshore area is subsiding while contemporaneously uplift of the mainland can be observed the study sector records the same uplift rates both during mis 5 5 and the holocene in contrast to the other areas of sicily

late quaternary stratigraphic setting of the sibari plain southern italy hydrogeological implications abstract the aim of this study is the reconstruction of the late pleistocene holocene stratigraphy of the sibari plain southern italy aimed to obtain information about hydrogeological framework a multidisciplinary approach combining boreholes data and electrical resistivity tomography allowed us to recognize three electro stratigraphic units which consist of upper pleistocene fluvial and floodplain littoral facies deep aquifer passing upward to holocene marine transitional deposits aquiclude evolving toward continental sediments shallow aquifer related to the crati delta progradation the late quaternary holocene plain evolution took place in a tectonic controlled setting and was driven by the interaction between sea level variations and local factors the presence of a ne sw fault zone controlled the facies and thickness of holocene sediments along strike of the fault this active fault zone contributed to determine the plain stratigraphic architecture the arrangement of the depositional environments and consequently the stratigraphic pattern

an evaluation of criteria to deduce the sense of movement in sheared rocks some of the most useful criteria for the deduction of the sense of shear are summarized for use in areas where unequivocal field evidence is lacking apparently conflicting evidence from rotated pressure shadow regions around porphyroclasts and porphyroblasts is clarified the use of quartz crystallographic fabric asymmetry to deduce the shear sense in the bulk rock should be treated with caution and used only together with detailed microstructural observations

simple shear deformation and quartz crystallographic fabrics a possible natural example from the torridon area of nw scotland ln this paper the microstructures and crystallographic fabrics of a 30 cm wide deformed quartz vein from the torridon area of nw scotland are described the vein which lies along a joint separating two blocks of proterozoic gneiss was deformed by crystal plastic processes when the rigid joint blocks moved in opposite directions parallel to the vein margins mylonitic foliation within this quartzose ductile shear zone locally displays the classic orientation variation expected for heterogeneous simple shear deformation in thin section the vein is a mylonite composed of dynamically recrystallized elongate quartz grains aligned oblique to the mylonitic foliation fabrics within the central part of the vein have been examined by optical and x ray texture goniometry methods together with orientation distribution function odf analysis the a axis fabric consists of a dominant single point maximum orientated within the xz plane at 9 to the lineation x this point maximum occupies a pole position to the corresponding single girdle c axis fabric for individual positions on the c axis fabric skeleton the orientations of potential crystallographic slip systems slip plane and direction relative to shear zone co ordinates have been calculated by odf analysis the calculation of relative resolved shear stresses schmidfactors for the potential slip systems assuming a simple shear kinematic framework reveals an elegantly simple relationship between individual grain c axis orientation and correspond ing orientations of potential slip systems these results are readily interpreted in terms of bulk simple shear deformation

a new empirical calibration of the quartz c axis fabric opening angle deformation thermometer abstract the opening angle of quartz c axis fabrics oa is strongly temperature dependent and has proven to be a powerful deformation thermometer for natural metamorphic rocks previous considerations of empirical data have identified a linear correlation between oa and temperature between 250 and 650 c and no correlation above 650 c however possible effects of pressure have not been investigated we expanded the data set of oa versus temperature including data from rocks deformed over 300 1050 c and 2 5 15 kbar disregarding possible effects of pressure the oa temperature relationship can be described by two linear correlations for the intervals 250 650 c and 650 1050 c t c 6 9 o a degrees 48 250 c t 650 c and o a 87 t c 4 6 o a degrees 258 650 c t 1050 c and o a 87 the change on the curve slope of the oa temperature relationship correlates approximately to the low to high quartz transition and to changes in the dynamic recrystallization mechanism from subgrain rotation to grain boundary migration the available data suggest that pressure has a secondary effect accompanying the major temperature dependence of oa which is particularly important for temperatures above 650 c where the correlation between oa and temperature is less pronounced for fixed pressures the oa has logarithmic relationships with temperature over the range 250 1050 c the following thermometer equation is formulated from a multiple regression t c 410 44 ln oa degrees 14 22 p kbar 1272 an uncertainty of 50 c is inherited from the petrological temperature estimates of the natural samples the data suggest the gradual increasing importance of prism c slip relative to slip in quartz with rising temperature under conditions of average geological strain rate and water weakening prism c slip dominates for deformation above 700 c

microscopic anatomy of a hot on cold shear zone insights from quartzites of the main central thrust in the alaknanda region garhwal himalaya

fabric development during shear deformation in the main central thrust zone nw himalaya india abstract quartz microfabrics and associated microstructures have been studied on a crustal shear zone the main central thrust mct of the himalaya sampling has been done along six traverses across the mct zone in the kumaun and garhwal sectors of the indian himalaya the mct is a moderately north dipping shear zone formed as a result of the southward emplacement of a part of the deeply rooted crust that now constitutes the central crystalline zone of the higher himalaya over the less metamorphosed sedimentary belt of the lesser himalaya on the basis of quartz c and a axis fabric patterns supported by the relevant microstructures within the mct zone two major kinematic domains have been distinguished a noncoaxial deformation domain is indicated by the intensely deformed rocks in the vicinity of the mct plane this domain includes ductilely deformed and fine grained mylonitic rocks which contain a strong stretching lineation and are composed of low grade mineral assemblages muscovite chlorite and quartz these rocks are characterized by highly asymmetric structures microstructures and quartz c and a axis fabrics that indicate a top to the south sense that is compatible with south directed thrusting for the mct zone an apparently coaxial deformation domain on the other hand is indicated by the rocks occurring in a rather narrow belt fringing and structurally above the noncoaxial deformation domain the rocks are highly feldspathic and coarse grained gneisses and do not possess any common lineation trend and the effects of simple shear deformation are weak the quartz c axis fabrics are symmetrical with respect to foliation and lineation moreover these rocks contain conjugate and mutually interfering shear bands feldspar quartz porphyroclasts with long axes parallel to the macrosopic foliation and the related structures microstructures suggesting deformation under an approximate coaxial strain path on moving towards the mct the quartz c and a axis fabrics become progressively stronger the c axis fabric gradually changes from random to orthorhombic and then to monoclinic in addition the coaxial strain path gradually changes to the noncoaxial strain path all this progressive evolution of quartz fabrics suggests more activation of the basal rhomb and a slip systems at all structural levels across the mct

direct measurement of the quartz c axis using neutron diffraction abstract quartz c axis pole figures are widely used across structural geology and geophysics to gain insights into crustal properties yet their direct measurement using bulk diffraction techniques has hitherto been unsuccessful in this contribution we present measurements of the quartz c axis using neutron diffraction this has been achieved by combining advances in neutron diffraction instrumentation high neutron fluxes and fast data acquisition with carefully performed diffraction pattern analysis to resolve low intensity diffractions on the 003 diffraction peak hidden in the shoulder of the higher intensity 112 peak these measurements have allowed us to assess recalculated c axis pole figures i e those predicted from odf functions against measured c axis pole figures and thus assess the reliability of quartz c axis pole figures past and present we find that measured and recalculated pole figures are generally in good agreement in both strongly and weakly textured rocks and that inclusion of the 003 pole figure into quartz texture analysis routines improves odf construction

geomorphological features of the archaeological marine area of sinuessa in campania southern italy abstract submarine surveys carried out since the 90s along the coastland of sinuessa allowed us to draw up a geomorphological map with archaeological findings along the sea bottom 650 m off and 7 m depth a campanian ignimbrite bedrock was detected dated 39 kyr bp its position is incompatible with the current sea level towards the northern edge of the shoal a depressed area with 24 cubic elements in concrete was surveyed these artefacts pilae are typical of roman maritime structures widespread along the southernmost phlegrean coast beachrocks and accessory landforms at the same depth of bedrock suggest that this was emerging and attended by man in roman times even for activities related to port facilities submerged palaeo channels in alignment of current watercourses on the mainland dissect the shoal these channels were moulded in subaerial environment during wurm glaciation following the tuff deposition and then were drowned by sea level rise the northernmost channel next to the pilae likely allowed transit and manoeuvring of roman ships the discovery along the seabed of a large stump of lead anchor hundreds of roman amphorae and fragments as well as of a depression of millstone confirm this finding probably the sinuous physiography favored the choice of this site for the docking of sinuessa as sheltered from storms

new insights on the relative sea level change during holocene along the coasts of tunisia and western libya from archaeological and geomorphological markers new data of sea level changes for the mediterranean region along the coasts of northern africa are presented data are inferred from archaeological sites of punic roman age located along the coast of tunisia between tunis and jerba island and along the western coast of libya between sabratha and leptis magna data are based on precise measures of presently submerged archaeological markers that are good indicators of past sea level elevation nineteen selected archaeological sites were studied in tunisia and four in libya all aged between 2 0 and 1 5 ka bp the functional elevations of significant archaeological markers were measured with respect to the sea level at the time of measurements applying corrections for tide and atmospheric pressure values the functional elevations of specific architectural parts of the sites were interpreted related to sea level at the time of their construction providing data on the relative changes between land and sea observations were compared against sea level change predictions derived from the glacio hydro isostatic model associated with the last glacial cycle the results indicate that local relative sea level change along the coast of tunisia and libya has increased 0 2 0 5 m since the last 2 ka besides minor vertical tectonic movements of the land the observed changes are produced by eustatic and glacio hydro isostatic variations acting in the mediterranean basin since the end of the last glacial maximum

submerged archaeological sites along the ionian coast of southeastern sicily italy and implications for the holocene relative sea level change abstract precise measurements of submerged archaeological markers in the siracusa coast southeastern sicily italy provide new data on relative sea level change during the late holocene four submerged archaeological sites have been studied and investigated through direct observations two of them are greek archaic in age 2 5 2 7 ka and are now 0 98 1 48 m below sea level the other two developed during the bronze age 3 2 3 8 ka and are now 1 03 1 97 m below sea level these archaeological data have been integrated with information derived from a submerged speleothem collected in a cave located along the siracusa coast at 20 m depth the positions of the archaeological markers have been measured with respect to present sea level corrected for tide and pressure at the time of surveys these data were compared with predicted sea level rise curves for the holocene using a glacio hydro isostatic model the comparison with the curve for the southeastern sicily coast yields a tectonic component of relative sea level change related to regional uplift uplift rates between 0 3 and 0 8 mm yr have been estimated

intracrystalline vorticity record of flow kinematics during shear zone reactivation abstract the vorticity axis of deformation of a shear zone is a rotational axis controlled by the relative movement of its boundaries when characterized it is a reliable tool to determine the ductile flow geometry monoclinic general monoclinic transpressive or triclinic and an asset to identify the kinematics of complex oblique collisions advancements in analysis of electron backscattered diffraction ebsd maps now permit inference of vorticity axes known as crystallographic vorticity axes cvas from the intragranular lattice orientation dispersion of strain bearing minerals however natural shear zones may preserve a record of multiple shear events with contrasting kinematics and it is not understood to which extent the quartz lattice may preserve a kinematic record through multiple deformation events herein we characterize the finite flow kinematic record produced during reactivation of the eastern highlands shear zone ehsz in an oblique collision within the canadian appalachians we integrate field and thin section observations quartz lattice preferred orientations ebsd maps and grain classification leading to a new method to determine and compare cva within relict and recrystallized quartz grains using this method we were able to conclude that the ehsz was reactivated in an heterogenous monoclinic flow environment

heterogeneous deformation and quartz crystallographic fabric transitions natural examples from the moine thrust zone at the stack of glencoul northern assynt quartz crystallographic fabric transitions in well exposed mylonites immediately beneath the moine thrust at the stack of glencoul nw scotland have been investigated by optical microscopy x ray texture goniometry and orientation distribution function analysis a progressive change is observed from asymmetrical kinked single girdle c axis fabrics at 0 5 cm beneath the moine thrust through asymmetrical type i cross girdle fabrics to symmetrical type i cross girdle fabrics at 30 cm beneath the thrust this c axis fabric transition is accompanied by a transition from asymmetrical single a axis maximum fabrics 0 5 cm beneath the thrust through asymmetrical two maxima fabrics to essentially symmetrical two maxima a axis fabrics odf analysis of these s l and l s tectonites indicates that c axis positions on the leading edge of the fabric skeleton are related by a common a direction oriented within the xz plane at a moderate angle to the lineation x in contrast c axis positions on the peripheral trailing edge are related by a positive r rhomb pole oriented close to z a directions lying within this common rhomb plane progressively change through 180 in orientation traced around the c axis fabric skeleton such contrasting single crystal rhomb a preferred orientations on the leading and trailing edges of the fabric skeleton are interpreted as indicating localized grain scale plane strain and flattening deformation respectively they result in tectonites with essentially symmetrical c and a axis fabrics which display strongly asymmetrical positive r and negative z rhomb pole figures the observed transition in quartz c and a axis fabrics is interpreted as indicating an increasing importance of non coaxial plane strain deformation as the moine thrust is approached even immediately 1 cm beneath the thrust however flow has still significantly departed from bulk simple shear and involved an important heterogeneous component of contemporaneous flattening deformation

kinematics nature of deformation and tectonic setting of the taxaquara shear zone a major transpressional zone of the ribeira belt se brazil abstract in this paper we have investigated the taxaquara shear zone tsz a major strike slip structure within the ribeira belt rb se brazil in order to assess its kinematics the nature of deformation of rocks affected by the tsz and its tectonic setting the tsz presents a vertical ne trending mylonitic foliation and ene to wsw stretching lineation with variable plunge granitic rocks are intensely deformed giving rise to mylonites with newformed matrix assemblage quartz oligoclase k feldspar biotite muscovite rutile magnetite this assemblage within a pseudosection couple with muscovite biotite thermometer helps to constrain a metamorphic condition during deformation which spans 513 525 c and 3 9 4 4 kbar with mean peak at 520 c and 4 0 kbar quartz accommodates deformation through dislocation creep achieving subgrain rotation with minor contribution of grain boundary migration at a mean strain rate of 10 13 10 12 s 1 feldspar porphyroclasts record brittle deformation microfaults and evidences of dislocation creep e g kink twinning the cpos for monomineralic quartz ribbons display monoclinic pattern and activation of basal rhomb slip systems during deformation however the cpos for quartz and feldspar from fine grained polyphase matrix show a switch in deformation mechanism from dislocation creep to diffusion creep the vorticity and three dimensional finite strain data results suggest that the tsz was developed under a moderate to high strain conditions and a transpressional sub simple shear environment with predominance of simple over pure shear regional correlation with other structures from the ribeira belt and african belts based on finite strain quantification support that a major transpressional system was mainly responsible for the shear zones development during late stages of braziliano pan african orogeny

pleistocene sea level changes sapping processes and development of valley networks in the apulia region southern italy abstract the central area of the apulia region is characterized by a network of valleys with peculiar features locally called gravine or lame they are short straight valleys deeply incised in plio pleistocene calcareous sandstones and in mesozoic limestones these characteristic valleys cut a staircase of marine terraces a series of valley generations is recognisable each one of them leading to the internal margin of a marine terrace representing its base level morphological features and hydrogeological conditions suggest that sapping processes were responsible for the development of the valley network as the aquifer rests on seawater intruding from the nearby coastal area sapping processes were enhanced during interglacial high sea level stands so that each ancient coastline is marked by its own generation of valleys however the longest and deepest valleys formed at the ionian side during ois 7 this is due mostly to a fast sea level rise accompanied by very humid climatic conditions that increased the hydraulic head at the springs and the intensity of sapping processes sapping valleys could be useful for regional correlation of marine terraces and as indicators of relict coastlines at present placed below sea level

millstone coastal quarries of the mediterranean a new class of sea level indicator abstract the coasts of italy still preserve several remnants of coastal quarries built in antiquity that now provide insights into the intervening sea level changes occurred during the last millennia in this paper we show and discuss a new class of sea level indicator consisting of millstones carved along the rocky coast of southern italy since 2500 bp that are currently submerged they were extracted from beachrocks sandstones or similar sedimentary rocks easier for carving by ancient carving tools our study focuses on 10 coastal sites located at capo d orlando avola and letojanni in sicily soverato tropea and capo dell armi in calabria castellabate palinuro and scario in campania and polignano san vito in apulia unfortunately only limited archaeological information is available for these anthropic structures scario one of these millstone quarries discussed here has been dated through independent archaeological remains allowing us to restrict the exploitation age to the end of xvii century present day elevations of these coastal sites were obtained through geo archaeological surveys calibrated using the nearest tidal stations together with geomorphological and tectonic interpretations data were compared against the latest sea level predictions based on glacio hydro isostatic models our results allow proposal of the age range of these millstone quarries and to estimate the intervening relative sea level changes since the time when they were carved

anomolous multi origin marine notch sites three case studies in the central mediterranean sea abstract we present and discuss the genesis age and evolution of indented landforms carved at sea level in correspondence of carbonatic headlands in three sites of the central mediterranean coasts between marseille france and balzi rossi italy the island of tavolara sardinia italy and the promontory of tindari sicily italy the shape of these anomalous notches landforms can be referred to is very similar to tidal notches despite their genesis and morphometric parameters are different from those suggested by other authors for the central mediterranean area two of these sites are located in tectonically stable areas while the third falls is located in an uplifting area those the notches we investigated along the coast of southern france are submerged notch type landforms located in the vicinities surroundings of current modern tidal notches at tavolara island these anomalous notches are placed at about 25 m b s l these landforms and have the shape of mushroom like notches finally those investigated along the metamorphic carbonatic promontory of tindari are marine and abrasional notches that have been uplifted likely during the holocene

the grotta grande of scario salerno italy archaeology and environment during the last interglacial mis 5 of the mediterranean region abstract archeological and paleo environmental researches carried on the grotta grande site illustrate the importance of a multidisciplinary approach among archeologists palynologists and paleontologists the archaeology fauna pollen and micro charcoal recovered in two short sedimentary successions trenches a f located close to the entrance of the cave are discussed the cave opens directly on the tyrrhenian sea 2 km from scario salerno campania southern italy the morphology of the cave and sedimentary processes were controlled by eustatic fluctuations during the late middle pleistocene and the early late pleistocene the sea repeatedly occupied the cave the cave was frequented by humans of middle palaeolithic culture archaeological and faunal record of the two trenches can be positioned within the climatic fluctuation posterior to the warm interglacial mis 5e peak pollen have been retrieved in the older series b c of trench a referable to mis 7 6 the most important archaeological finds are the occurrence of structures that indicate the living space trench f together with hearths and lithic industry the latter is characterised by the presence of the levallois system and by the prevalence of sidescrapers among tools the systematic use of limestone is observed only in trench f large and small mammal remains recovered within the two trenches show that in the neighbourhood of the site a diversified assemblage occurred including eleven large mammals among which the hippo the straight tusked elephant and the narrow nosed rhino are noteworthy and fourteen small mammal taxa mainly rodents with a significant amount of glirids the fauna is indicative of a temperate forested mediterranean environment variation of faunal composition suggests that environments underwent some minor fluctuations towards cooler and or drier landscapes pollen indicates vegetation organized in different belts mainly mediterranean evergreen forest maquis and mixed forest with conifers and deciduous broadleaved trees fresh water plant communities are mainly represented in trench a some records of tertiary taxa suggest stands of survival of these plants in the surroundings of the cave over the time span the landscape become more open due to some episodes of steppe vegetation spread caused by variation in temperature and humidity deposit of this age are rather uncommon even in the italian peninsula and therefore the integration of sedimentological archaeological faunal and palynological data provides an important piece of information to the puzzling reconstruction of the late pleistocene mediterranean environments before the onset of the glaciation

deformation thermometry based on quartz c axis fabrics and recrystallization microstructures a review abstract for quartz rich tectonites two types of deformation thermometer are currently commonly employed 1 the quartz c axis fabric opening angle thermometer that provides an estimate of deformation temperatures when fabrics were locked in during dislocation creep and dynamic recrystallization 2 the quartz recrystallization thermometer that indicates a range of likely deformation temperatures based on observed microstructures and inferred mechanisms of dynamic recrystallization a critically important caveat in applying both thermometers is the assumption that deformation temperature is the primary controlling factor in recrystallization mechanisms and fabric development however fabric opening angles and recrystallization mechanisms are also sensitive to other variables such as strain rate and water weakening in this paper the development of these thermometers is reviewed and their potential sensitivities to competing factors such as temperature strain rate water weakening and in the case of opening angles 3d strain type are discussed examples of the application of these potential thermometers to naturally deformed quartz rich rocks are given and case studies of correlations between deformation temperatures estimated by these thermometers and temperatures of synkinematic metamorphism determined by petrology based thermobarometers are highlighted in the review attention is focused on problems associated with applying these thermometers to natural deformation and examples of such problems are discussed

comparison between coastal and inland karst limestone lowering rates in the northeastern adriatic region italy and croatia a comparison among lowering rates collected in the limestones of the northeastern adriatic region italy and croatia gives a picture of the erosion patterns in the inland and coastal classical karst and istrian karst erosion rates were measured using either a micro erosion meter or a traversing micro erosion meter beginning from a large dataset spread over a maximum of 26 years significant differences in limestone lowering rates have been recognized in the surveyed area the mean lowering rate for the inland classical karst area is 0 018 mm yr whereas in the inland istrian karst it is 0 009 mm yr in the coastal sectors the mean erosion rate varies between 0 14 mm yr in the gulf of trieste and 0 04 mm yr in the sites located along the istrian shoreline these differences are probably due to the climatic setting of the classical karst area mediterranean continental to sub alpine climate and istrian peninsula mediterranean climate moreover along the coasts of the gulf of trieste there are many submarine springs which are absent along the istrian coast it is hypothesized that these underwater springs stress the effect of rainfall along the coast which is both direct rain on the measurement site and mainly indirect freshwater outflow from submarine springs higher lowering rates were surveyed during autumn rainfall therefore also freshwater outflow from submarine springs is particularly high at the end of the summer and in autumn

rheology of a coaxial shear zone in the virginia blue ridge wet quartzite dislocation creep at 250 280 c abstract cambrian quartzite along the western margin of the blue ridge near front royal virginia records significant penetrative strain under subgreenschist facies conditions strain analyses of the quartzite indicate general flattening and octahedral shear strain values up to 1 25 x z up to 5 7 1 samples with x z as low as 1 5 1 have crystallographic preferred orientations that record a dominance of basal slip and patterns consistent with coaxial flattening in most samples quartz has undergone minor amounts of dynamic recrystallization with mean grain sizes 4 5 m locally the quartzite is brittlely deformed and subgrains and recrystallized bulges are present along fractures and extinction bands fluid inclusion planes and fluid inclusions along deformation lamellae are abundant and quartz ftir analyses yield average h 106si values of 1100 3300 indicating fluid flow and high intragranular water content during deformation higher strain samples generally record lower water contents which may indicate that fluids migrated to grain boundaries during deformation dissolution microstructures are rare in high strain samples and we interpret most strain to have been accommodated by dislocation creep thermal modeling of zircon low temperature thermochronology data coupled with quartz c axis opening angle thermometry suggest deformation temperatures were likely 250 280 c these deformation temperatures are lower than what is typically considered the brittle plastic transition in quartz we attribute localization of this high strain zone and dislocation creep at these temperatures to hydrolytic weakening and a relatively low strain rate estimated to be 10 15 s 1

pure shear dominated transpression and vertical extrusion in a strike slip fault splay from the itapirapua shear zone ribeira belt brazil abstract the itapirapua shear zone is a major ne trending dextral transcurrent zone from the southern ribeira belt brazil which was active during the neoproterozoic brasiliano pan african orogeny related with west gondwana assembly macroscopic sigmoid shaped blocks in its northernmost splay termination present a ne trending subvertical tectonic foliation and subvertical stretching lineation suggesting a transpressional tectonics this paper investigates this splay termination using integration of data from geological mapping thermodynamic modeling microtectonics quartz c axis fabrics kinematic vorticity and finite strain analysis distinct rock assemblages are placed in tectonic contacts along the splay termination including statherian sillimanite biotite paragneiss and granitic orthogneiss apiai mirim complex statherian phyllites bairro dos prestes formation calymmian chlorite epidote actinolite metabasites fazenda velha suite ediacaran phyllites metalimestone and quartzite itaiacoca group and ediacaran granite tres corregos suite isochemical phase diagrams constrain synkinematic metamorphic conditions of 490 510 c and 11 12 5 kbar chlorite biotite phengite phyllite 520 560 c and 9 10 kbar biotite phengite phyllite and 680 690 c and 5 6 kbar sillimanite biotite paragneiss with isothermal decompression paths microstructural evidence suggests that increase in metamorphic temperatures were accompanied by changes in the dominant deformation mechanism in quartz aggregates from subgrain rotation to grain boundary migration recrystallization significant contribution of dissolution precipitation creep indicates water abundant deformational conditions strain ellipsoids are oblate shaped and present ne trending subvertical xy planes and subvertical x axes in agreement with field tectonic fabric quartz c axis fabrics in xz sections of the strain ellipsoid are dominated by symmetrical crossed girdles while the fabrics present dextral asymmetry in horizontal yz sections consistent with macroscopic structural deflection indicating a subvertical vorticity axis vorticity results indicate 48 59 of pure shear contribution the data indicate that strain in the itapirapua shear zone northern termination was accommodated by a pure shear dominated transpression with vertical extrusion at mid crustal conditions which contrasts with a transtensional deformation in the southeastern block

sea level change and vertical land movements since the last two millennia along the coasts of southwestern turkey and israel abstract this paper provides new relative sea level data inferred from coastal archaeological sites located along the turkish coasts of the gulf of fethye 8 sites and israel between akziv and caesarea 5 sites the structures selected are those that for effective functioning can be accurately related to sea level at the time of their construction thus their positions with respect to present sea level provide a measure of the relative sea level change since their time of construction useful information was obtained from the investigated sites spanning an age range of 2 3 1 6 ka bp the inferred changes in relative sea level for the two areas are distinctly different from a rise of 2 41 to 4 50 m in turkey and from 0 to 0 18 m in israel sea level change is the combination of several processes including vertical tectonics glacio hydro isostatic signals associated with the last glacial cycle and changes in ocean volume for the israel section the present elevations of the mis 5 5 tyrrhenian terraces occur at a few meters above present sea level and vertical tectonic displacements are small data from gps and tide gauge measurements also indicate that any recent vertical movements are small the mis 5 5 shorelines are absent from the investigated section of the turkish coast consistent with crustal subsidence associated with the hellenic arc the isostatic signals for the israel section of the coast are also small ranging from 0 11 mm yr to 0 14 mm yr depending on site and earth model and the observed eustatic average sea level change corrected for this contribution is a rise of 13 5 2 6 cm during the past 2 ka this is attributed to the time integrated contribution to sea level from a combination of thermal expansion and other increases in ocean volume the observed sea levels from the turkish sites in contrast indicate a much greater rise of up to 2 2 mm yr since 2 3 ka bp occurring in a wide area between knidos and kekova the isostatic signal here is also one of a rising sea level of up to 1 mm yr and site and earth model dependent and the corrected tectonic rate of land subsidence is 1 48 mm yr this is the primary cause of dramatic relative sea level rise for this part of the coast

tracing sea level changes during the mid holocene in the southern mediterranean coast an example from the gulf of gabes abstract mid holocene sea level emergence was recorded along a mid latitude coastal site in the gulf of gabes tunisia in beach rock deposits however the post emergence sea level curve and associated hydro sedimentary processes have rarely been documented this study presents new records of sea level changes along the tunisian coast since the mid holocene each phase of the sea level curve was evidenced and supported by lithostratigraphic morphological and archaeologic markers post emergence sea level fall due to postglacial isostatic rebound was recognized in regressive sequences which vary depending on available accommodation space from a small pocket beach to a well developed dune system sea level stabilization following isostatic rebound has promoted the end phase deposits of the regressive sequences however this stability was interrupted during the late holocene by a high energy storm event that accumulated a transgressive boulder unit at 2 m above present shape and disposition of the boulder ridge behind a prograding modern shoreline suggests that sea level has not changed during the late holocene the existence of a roman fish pond on the upper foreshore confirms stability of sea level during the last two millennia the combination of lithostratigraphic morphological and archaeologic markers represents a tool for improving the accuracy of dating of erosional and depositional periods in mid coastal sections

new insights on the subsidence of lipari island aeolian islands southern italy from the submerged roman age pier at marina lunga abstract lipari island belongs to the aeolian archipelago located in the southern tyrrhenian sea italy which is one of the most active volcanic areas of the mediterranean basin although this region has been settled since prehistory only during roman times were coastal installations built in these islands in this study we present and discuss data on the relative sea level change estimated from a submerged pier of roman age dated 2100 100 bp this structure about 140 60 m is located along the coast of marina lunga corresponding to the present location of the main harbor of lipari island this pier which was accidentally discovered in 2008 during preliminary excavations for the construction of a new pier is a valuable indicator of relative sea level changes and vertical land movements its top surface is presently located at 9 1 0 05 m while the foundations at the outer end of the pier are at 11 6 0 05 m above a shoreline placed at 13 0 0 05 m we studied this site through direct archaeological investigations and ultra high resolution multibeam bathymetry the current submergence of this pier can be explained by the cumulative effect of the relative sea level changes caused by the regional glacio hydro isostatic signal active since the end of the last glacial maximum and the local volcano tectonic land subsidence from our investigations a relative sea level change at 12 3 0 7 m with a subsidence rate at 5 79 0 01 mm y 1 and an average value of volcano tectonic contribution at 5 17 0 01 m y 1 for the last 2100 100 years bp is estimated from comparison against the latest predicted sea level model for the southern tyrrhenian sea these rates of relative sea level change led to the disuse of the harbor after around the fourth century ad in agreement with archaeological interpretations our results provide new insights on the recent evolution of this active volcanic area

archaeological remains as sea level change markers a review abstract the mediterranean sea constitutes a unique basin from an historical and archaeological point of view as it has been a privileged way of communication for thousands of years for the people that dwelled on its shores their passage has left many traces on the seabeds in the areas where the ancient commercial routes passed and remains of structures where moorings havens or dwellings existed some of these structures nowadays submerged offer interesting indications aiding the reconstruction of the ancient coastlines this contribution aims to examine recent work in coastal geo archaeology targeting both 1 gathering and discussion of the data particularly those pertaining to the italian coasts and 2 commentary on the methodological debate and verification of the possibility of a protocol that may contain unequivocal referring elements to investigate the archaeological evidence currently underwater because of the relative sea level variations harbour infrastructures fishponds villae maritimae caves nymphaei private or public buildings or town quarters pre and protohistorical villages quarries caves etc a clear and more coherent methodological assumption may be needed the archaeological interpretation must initially establish the maritime and or harbour nature and vocation of the site determine its typology and specific usage analyze the elements of its building techniques that reveal themselves as meaningful markers of height or depth at the time of building and its functional elements the measure of the emerged part with respect to the average sea level and point out the time of construction its chronological range of usage frequentation the dynamics of its abandonment destruction obliteration the evaluation of both the height and functional depth to the mean sea level depends on the typology of the archaeological evidence its use and the local tide amplitudes the surface of a pier surely has a functional elevation different from that of a haulage area or a platea or a pavement

sea level in roman time in the central mediterranean and implications for recent change instrumental records indicate that ocean volumes during the 20th century have increased so as to raise eustatic sea level by f1 2 mm year and the few available records suggest that this is higher than for the previous century geological data indicate that ocean volumes have increased since the main phase of deglaciation about 7000 years ago but whether this continued into the recent past remains unclear yet this is important for establishing whether the recent rise is associated with global warming or is part of a longer duration non anthropogenic signal here we present results for sea level change in the central mediterranean basin for the roman period using new archaeological evidence these data provide a precise measure of local sea level of 1 35f0 07 m at 2000 years ago part of this change is the result of ongoing glacio hydro isostatic adjustment of the crust subsequent to the last deglaciation when corrected for this using geologically constrained model predictions the change in eustatic sea level since the roman period is 0 13f0 09 m a comparison with tide gauge records from nearby locations and with geologically constrained model predictions of the glacio isostatic contributions establishes that the onset of modern sea level rise occurred in recent time at f100f53 years before present d 2004 elsevier b v all rights reserved

evidence for centennial scale sea level variability during the medieval climate optimum crusader period in israel eastern mediterranean the current study provides evidence supporting a sea level drop of up to about 50 20 cm at the eastern coasts of the mediterranean basin during the period ad 900 1300 the estimate is based on a variety of archaeological remains mostly from the crusader period compared with other archaeological and biological proxies of sea level from the periods before and after the crusader low levels overlap the period known as the medieval warm period mwp or the medieval climate anomaly mca on the basis of published data it appears that a positive north atlantic oscillation nao phase coincided with a negative southern oscillation index soi the former affecting the temperature and freshwater flux in the mediterranean sea and most of its rivers and the latter affecting the nile outflow changes of 0 125 psu in salinity and 0 4 c are estimated as upper limits for the change and these are expected to cause a sea level drop consistent in magnitude with the observed values these provide the upper limit for a regional climate forcing attribution of the observed sea level low the possibility of crustal uplifts contributing to the observed changes is also discussed

sea level change during the holocene in sardinia and in the northeastern adriatic central mediterranean sea from archaeological and geomorphological data abstract we provide new data on relative sea level change from the late holocene for two locations in the central mediterranean sardinia and ne adriatico they are based on precise measures of submerged archaeological and tide notch markers that are good indicators of past sea level elevation twelve submerged archaeological sites were studied six aged between 2 5 and 1 6 ka bp located along the sardinia coast and a further six dated 2 0 ka bp located along the ne adriatic coast italy slovenia and croatia for sardinia we also use beach rock and core data that can be related to holocene sea level the elevations of selected significant archaeological markers were measured with respect to the present sea level applying corrections for tide and atmospheric pressure values at the time of surveys the interpretation of the functional heights related to sea level at the time of their construction provides data on the relative changes between land and sea these data are compared with predictions derived from a new glacio hydro isostatic model associated with the last glacial cycle sardinia is tectonically relatively stable and we use the sea level data from this island to calibrate our models for eustatic and glacio hydro isostatic change the results are consistent with those from another tectonically stable site the versilia plain of italy the northeast adriatic italy slovenia and croatia is an area of subsidence and we use the calibrated model results to separate out the isostatic from the tectonic contributions this indicates that the adriatic coast from the gulf of trieste to the southern end of istria has tectonically subsided by 1 5 m since roman times

geochemistry and trade of eastern mediterranean millstones from the neolithic to roman periods millstones and grindstones of the prehistoric to roman periods include saddle querns rectangular hopper rubber mills rotary querns and pompeian style donkey mills many of these were manufactured from igneous rocks which can be provenanced to their geological sources using chemical analysis giving information about trade contacts of sites sixty nine samples of 10 20 g each were removed from broken parts of lava millstones of prehistoric and early historic date from sites in israel syria egypt greece and turkey these were analysed for major and trace elements using x ray fluorescence and petrological features were examined in thin section the millstones were all young generally fresh lavas ranging from vesicular basalt to porphyritic andesite potential sources occur in younger volcanics of mainland greece the aegean turkey and the levant israel syria and jordan and in egypt thirty four geological samples from israel syria and turkey were collected and analysed in the same way as the archaeological samples and an intensive literature survey carried out to supplement these by published analyses comparison of archaeological samples with source data is done by using a series of discrimination graphs following a simple flow diagram the archaeological samples were of two types within plate lavas and island arc or other subduction related lavas all samples were successfully assigned to sources and results show use of the source areas as follows during the prehistoric period neolithic bronze age pre 6th century bc iron age samples saddle querns in mainland greece were made of aegina andesire while sites in north syria used local syrian lavas and in israel basalts from near lake tiberias and from the dead sea area were used earlier work by the authors and others has shown import of levant millstones to cyprus in the late bronze age hopper rubbers of the 5th century bc onwards were made at specialized quarries in aegean islands on nisyros kimolos and santorini and exported to mainland greece western turkey egypt and cyprus less well finished hopper rubbers were made and used in western turkey and in israel roman pompeian style mills were made of levant lavas from several sources particularly around lake tiberias and were transported within israel as well as to cyprus as shown by earlier studies rotary querns were made of lavas from santorini and probably nisyros and of locally used west anatolian rocks rotary querns of roman and later 10th 12th century ad dates were also produced at several sources in the levant again around lake tiberias and probably in north syria and within the dead sea volcanics for use within israel olive crushing trapeta used in turkey and greece were manufactured from andesites from anatolia and aegina respectively west anatolian lavas mill types unknown have also been identified at roman sites in the eastern desert of egypt millstone distributions increased in complexity and extent over time with hopper rubbers being traded up to 820 km from sources and roman rotary millstones up to 1300 km the three major source areas aegean anatolia and the levant were in apparent competition by the roman period when there is extensive overlap of distributions from different sources with aegean and anatolian products traded the furthest the millstone trade in the eastern mediterranean is separate from that of the west mediterranean west of greece except for one hopper rubber of nisyros lava identified in a shipwreck off mallorca this dichotomy is in marked contrast to the distribution of amphorae within which west mediterranean italian products were widely used in the east from at least the 2nd century bc stylistically east mediterranean millstones also show differences from those in the west in the prevalence of hopper rubbers and later in decorative features common on pompeian style mills

an illustration of the advantages of a complete texture analysis described by the orientation distribution function odf using quartz pole figure data abstract the preferred orientation of eight crystal directions of quartz was measured with an x ray texture goniometer for selected quartz bearing tectonites with a clear pattern of c axis preferred orientation the advantages of data analysis by means of calculations of the orientation distribution function and other forms of data presentation derived from the odf are demonstrated

vorticity analysis in a metachert from the sanbagawa belt sw japan abstract common tectonic features of deformed metachert include both sets of extended and shortened veins and quartz c axis preferred orientation patterns in such rocks information is also commonly available on the orientation and magnitude of the finite strain these features can be used to derive two independent estimates of the degree of non coaxiality during deformation in an example from the sanbagawa belt sw japan the two methods give consistent results and show that deformation was intermediate between simple and pure shear such types of progressive deformation distributed over a broad region could cause substantial subvertical thinning and be a significant factor in the exhumation of high p t rocks in the region

millstones as indicators of relative sea level changes in northern sicily and southern calabria coastlines italy abstract new data are presented for late holocene relative sea level changes in two coastal sites of sicily and calabria southern italy reconstructions are based on precise measurements of submerged archaeological remains that are valuable indicators of past sea level position the archaeological remains are millstone quarries carved on sandstone coastal rocks and nowadays partially submerged which to the authors knowledge are used for the first time as sea level markers millstones of similar typology are located on the coast of capo d orlando northern sicily and capo dell armi southern calabria when the archeologically based sea level position is compared with the shoreline elevation provided by geological markers holocene beachrock late pleistocene marine terraces a refined understanding of relative sea level changes and rates of vertical tectonic movements for these coastline locations is gained

millstone quarries along the mediterranean coast chronology morphological variability and relationships with past sea levels abstract the coast of the mediterranean provide several remnants of ancient coastal quarries which are now useful to study sea level change occurring during the last millennia millstones quarries were exploited with same quarrying techniques from rocks like beachrocks sandstones or similar lithologies were shaped to be suitable to grind olives seeds and wheat to produce oil and flour or to break apart soft rocks in this study we integrated historical sources aerial photography field surveys and palaeo sea level modelling to investigate a number of millstones quarries with the aim to asses the intervening sea level change that occurred since the quarries were abandoned we investigated on their chronology spatial distribution and spatial relationship to the sea level our results indicate that most of these were carved close to sea level between 1 45 ka and 0 25 ka cal bp but mainly around 0 45 cal ka bp despite the uncertainties associated with the chronology in we found good agreement between their lowest elevation between 0 33 m and 0 06 m and the paleo sea levels as predicted by the gia models

evolution of c axis pole figures and grain size during dynamic recrystallization results from experimentally sheared quartzite 1 quartzite samples experimentally sheared at conditions where subgrain rotation and grain boundary migration recrystallization are active show a striking change in the c axis crystallographic preferred orientation cpo with increasing shear strain up to 8 and degree of recrystallization up to 100 we used optical methods to determine the c axis cpo for the bulk samples and for porphyroclasts and recrystallized grains separately and to track the strengths of the cpos in five different orientation domains with increasing the c axis pole figure evolves from a broad peripheral maximum indicative of basal a slip to an inclined single girdle with two maxima indicative of rhomb a slip and finally an elongate single maximum at the girdle center indicative of prism a slip throughout this sequence the fabric skeleton rotates with the sense of shear the bulk preferred c axis orientation results from growth and shrinkage of differently oriented crystallographic domains grain boundary density analysis indicates that the size of prism a recrystallized grains is 1 5 times that of average and 2 times that of rhomb grains indicating that prism a slip is significantly easier at our experimental conditions this inference is supported by autocorrelation function analysis of the various orientation domains and how they evolve with strain similar progressive changes in c axis cpo are observed in quartzites naturally sheared at conditions where grain boundary migration recrystallization operates these results indicate that achievement of microstructural and mechanical steady state requires high strain and complete recrystallization

prism and basal plane parallel subgrain boundaries in quartz a microstructural geothermobarometer empirical data on quartz subgrain patterns from various metamorphic rocks show that at least up to 10 kbar in the stability field of low quartz prismatic subgrain boundaries are dominant whereas basal subgrain boundaries are not developed in the high quartz stability field both prismatic and basal subgrain boundaries occur and form typical rectangular chessboard patterns the likely reason behind the different occurrence of these subgrain patterns is that in high quartz prismatic glide becomes as easy as or probably even easier than basal glide the two types of subgrain patterns can be clearly distinguished by optical microscopy consequently the occurrence of chessboard subgrain patterns in quartz represents a practicable geothermobarometer the possibilities of its application are far reaching and include the specification of deformation conditions at high grade metamorphism the recognition of syntectonic intrusions and the distinction between pluton emplacement at lower and at higher crustal levels

a new technique for quantifying symmetry and opening angles in quartz c axis pole figures implications for interpreting the kinematic and thermal properties of rocks abstract variations in flow kinematics influence the type of crystallographic preferred orientations cpos in plastically deformed quartz yet we currently lack a robust means of quantifying the diagnostic symmetries that develop in the c axis 0001 pole figure in this contribution we demonstrate how the symmetry of common c axis topologies may be quantified by analysing the intensity distribution across a line transect of the pole figure margin a symmetry value s measures the relative difference in intensities between marginal girdle maxima in the pole figure and thus the degree to which the pole figure defines orthorhombic or monoclinic end member symmetries this provides a semi quantitative depiction of whether the rocks underwent coaxial or non coaxial flow respectively and may subsequently be used to quantify other topological properties such as the opening angle of girdle maxima the open source matlab toolbox mtex is used to quantify pole figure symmetries in quartzite samples from the main central thrust nw himalaya and the moine thrust nw scotland

texture development of recrystallised quartz polycrystals unravelled by orientation and misorientation characteristics abstract the development of microstructures and textures i e crystallographic preferred orientations during recrystallisation of naturally deformed quartz polycrystals has been studied via electron diffraction techniques in the scanning electron microscope in the investigated sample series of quartz rich rocks originating from different deformation regimes the microstructural and textural changes in quartz have been significantly influenced by dynamic recrystallisation based on microstructural observations paired with orientation and misorientation analyses down to the scale of grains and subgrains criteria could be established which characterise the dominant recrystallisation process and its influence on texture development it is shown that the texture development during dynamic recrystallisation is controlled by a differential activation of slip systems in grains of soft and hard orientations the analyses provide further evidence that specific grain orientations are preferred during crystal plastic deformation recrystallisation and grain growth the influence of twinning after the dauphine law was also investigated observations of a progressive reduction in the population of dauphine twin boundaries during recrystallisation and a penetrative deformation in both hosts and twins indicate a generation prior to deformation and recrystallisation a mechanical origin for twinning and possible influence on texture development was therefore discarded

evidence of vertical tectonic uplift at briatico calabria italy inferred from roman age maritime archaeological indicators abstract calabria is one of the most complex geological regions of the mediterranean basin which experienced large earthquakes and uplift and is still undergoing active tectonics along its coasts are located archaeological sites that can be used as powerful indicators of the relative vertical movements between land and sea since their construction this paper presents and discusses data on the relative sea level change as estimated from maritime archaeological indicators of the last 2 0 ka bp existing along the tyrrhenian coast of briatico these sites still show the remnants of a roman age fish tank and a submerged breakwater about 320 m long the palaeo sea level has been obtained measuring the functional elevation of the significant archaeological markers their elevation was compared against the latest predicted sea level curve for the holocene along the tyrrhenian coast of calabria as this coastal area is affected by significant and continuous vertical tectonic uplift during pleistocene the data show the counterbalance between coastal uplift and relative sea level change caused by the glacio hydro isostasy acting since the construction of these archaeological sites the sum of these movements determined an about null relative sea level change for this location these data are in contrast with other part of the tectonically stable areas of the mediterranean and provide evidence that crustal uplift continued in the last 1806 50 y at a rate of 0 65 mm y

deformation conditions and quartz c axis fabric development along nappe boundaries the andrelândia nappe system southern brasilia orogen brazil abstract the liberdade and andrel ndia nappes se brazil record the western gondwana amalgamation in the southern brasilia orogen during the ediacaran the liberdade shear zone acted as the boundary between these two overlapping nappes quartz c axis fabrics and strain data from quartzite samples and petrological data from hosting metapelite rocks were analyzed to investigate the tectonic processes involved in nappe development further constraints were achieved by conducting petrological modeling and geothermobarometry using p t isochemical phase diagram approaches quartz axis plots show consistency with different kinematic criteria verified in the field in meso and macroscale the fabrics are associated to both coaxial deformation and non coaxial deformation quartz microstructures metamorphic assemblages and c axis concentrations primarily around y and x structural directions suggest that deformation was accommodated by grain boundary migration recrystallization under temperature above 500 c disregarding pressure effects the opening angles of quartz c axis fabrics suggest temperatures between 480 and 640 c muscovite quartzite and 650 720 c sillimanite quartzite considering pressure data the opening angles indicate conditions of 550 650 c and 7 10 kbar muscovite quartzite and 600 730 c and 4 7 kbar sillimanite quartzite reflecting primarily distinct baric regimes sillimanite bearing samples estimatives are supported by ubiquitous presence of chessboard subgrain patterns in quartz and by modeled isochemical phase diagrams that constrain conditions of 660 730 c and 6 7 kbar for garnet sillimanite biotite schist samples altogether these results indicate progressive tectonic evolution linked to oblique convergence between tectonic units represented by the andrel ndia and liberdade nappes and the paleoproterozoic basement besides recording distinct thermal and baric regimes the nappes also present different structural styles suggesting that pressure and temperature are important boundary conditions for the nappe structural style

quartz deformation across interlayered monomineralic and polymineralic rocks a comparative analysis abstract given the increased availability of ebsd and fabric analyzer facilities quartz microstructural and cpo analysis have become tools of the trade for studies investigating crustal tectonics therefore improved understanding of the complexities of quartz deformation is needed to ensure that such analyses distinguish primarily between tectonic outcomes and artefacts of the quartz deformation behaviours in different deformed rock volumes we contribute to this understanding by comparing quartz deformation between monomineralic rocks which have simple compositions and polymineralic rocks which are more complex and representative of the crust mylonite quartzites and gneisses of the main central thrust nw himalaya are used for comparison under similar deformation conditions quartz inside monomineralic rocks forms well developed cpos and dynamically recrystallized microstructures typical of grain size insensitive gsi creep mechanisms quartz inside polymineralic rocks by contrast exhibits weak cpos and fine grained microstructures commonly interpreted as grain size sensitive creep but also exhibits lattice distortions e g undulose extinction sub grain boundaries associated with gsi creep we postulate that intrinsic factors such as interphase boundaries cause these ambiguous results the lack of clear evidence for deformation mechanisms in polymineralic rocks casts doubt on the reliability of quartz microstructures and cpos for rapid diagnoses of their rheology and broader tectonic significance

structural setting of a transpressive shear zone insights from geological mapping quartz petrofabric and kinematic vorticity analysis in ne sardinia italy

structures and fabrics in a crustal scale shear zone betic cordillera se spain abstract a broad zone of dominantly ductile high strain deformation lies beneath the aguilon nappe in the sierra alhamilla southern spain it forms part of a crustal scale movement zone traceable through much of the betic cordillera which separates the higher betic nappes from the underlying nevado filabride complex the zone is characterized in outcrop by a distinctive platy foliation and a strong nne trending stretching lineation microstructural characteristics include quartz ribbons mica fish augen of feldspar and other minerals in a matrix of dynamically recrystallized quartz and extensional crenulation cleavages narrow bands of ultramylonite and cataclasite occur within and on the margins of the movement zone deformation occurred under lower greenschist facies conditions and was accompanied by retrogression of earlier higher grade mineral assemblages structures in the movement zone developed in a temporal sequence beginning with isoclinal folding and transposition of older foliations this was followed by the formation of extensional crenulation cleavages and the progressive localization of strain into the ultramylonite bands mylonitic foliation in these bands is deformed by syn mylonite folds restricted to the bands all these structures were then deformed by s to se vergent small scale folds restricted to the movement zone as a whole cataclasis associated with alteration is localized along the ultramylonite bands and indicates a transition to late stage brittle deformation the lower boundary of the movement zone is gradational strain decreases recrystallized grainsize and the degree of recrystallization of quartz increases and pressure solution becomes the dominant deformation mechanism in mica schist asymmetric quartz fabrics in the movement zone indicate a nne sense of shear but variations in the degree of asymmetry suggest that flow was partitioned with the ultramylonite bands taking up much of the shear strain and the intervening rocks deforming more slowly and with a lower degree of non coaxiality diffuse fabrics in the fine grained ultramylonite bands may indicate a switch to a grainsize sensitive deformation mechanism and an overall downward increase in the opening angle of crossed girdle fabrics may reflect increased water activity at depth

fabric asymmetry and shear sense in movement zones asymmetry between lattice preferred orientation and shape fabrics is commonly observed in microstructural studies of many deformed mineral aggregates e g ice carbonate rocks peridotites and quartzites theoretical predictions are limited by the nature of the models available and more can be gained by discussion of the mechanisms which give rise to such asymmetry in specific natural and experimental situations

primeval displacements of the lunar pole abstract the hypothesis that the magnetic field which magnetized the lunar crust was generated by the dynamo process in a small fluid iron core can now be tested because the coriolis force was a dominant term in the equations of motion in this core the mean lunar field was aligned along the ancient axis of rotation from hood s modelling of the magnetic anomalies in the lunar crust mapped by the apollo 15 and 16 subsatellites the palaeo directions of this field have been determined from them palaeopole positions have been determined and are found to be grouped with respect to age the palaeoequators corresponding to ages 4 ga and 3 85 ga show close relationships with the circular maria or mascons on the near side and multi ring basins of corresponding age on the far side the polar displacements indicated from lunar palaeomagnetism can be explained by the changes in the moment of inertia tensor consequent on the excavation and later flooding of these circular mare small moons in the primeval earth moon system are inferred to be the impacting bodies