isotope geochemistry sr nd pb and petrogenesis of leucite bearing volcanic rocks from colli albani volcano roman magmatic province central italy inferences on volcano evolution and magma genesis the colli albani composite volcano is made up of strongly silica undersaturated leucite bearing rocks magmas were erupted during three main periods but a complex plumbing system dominated by regional tectonics channelled magmas into different reservoirs the most alkali rich magmas restricted to the caldera forming period pre caldera are extremely enriched in incompatible trace elements and display more radiogenic sr 87sr 86sr 0 71057 0 71067 with slightly less radiogenic pb with respect to those of the post caldera period post caldera volcanic activity was concentrated in three different volcanic environments external to the caldera along the caldera edge and within the caldera the post caldera magmas produced melilite to leucitite bearing plagioclase free leucitites in contrast to the pre caldera lavas they are characterised by lower incompatible trace element abundances and less radiogenic sr 87sr 86sr 0 71006 0 71039 magmas evolved through crystal fractionation plus minor crustal assimilation in a large magma chamber during the pre caldera period the multiple caldera collapses dissected and partially obliterated the early magma chamber during the post caldera stage magmas were channelled through several pathways and multiple shallow level magma reservoirs were established a lithospheric mantle wedge previously depleted in the basaltic component and subsequently enriched by metasomatic slab derived component is suggested as the mantle source of colli albani parental magmas two different parental magmas are recognised for the pre and post caldera stages the differences may be related to the interplay between smaller degrees of melting for the pre caldera magmas and more carbonate rich recycled subducted lithologies in the post caldera magmas

petrology and geochemistry of potassic and ultrapotassic volcanism in central italy petrogenesis and inferences on the evolution of the mantle sources major trace element sr isotopic and mineral chemical data are reported for mafic volcanic rocks mg value 65 from the northern central sector of the potassic volcanic belt of central italy the rocks investigated range from potassic series ks and high k series hks to lamproitic lmp and kamafugitic kam through a transitional series trans thus covering the entire compositional spectrum of potassic and ultrapotassic magmas kam rocks are strongly silica undersaturated and compared with the other rock series have low sio2 al2o3 na2o sc and v and high cao k na na k al ks and hks have high al2o3 cao and variable enrichment in k2o and incompatible elements lmp rocks are saturated in silica and have high sio2 k2o k2o na2 mgo ni and cr and low al2o3 cao na2o sc and v trans rocks display intermediate compositional characteristics between lmp and ks all the rocks under study have fractionated hygromagmaphile element patterns with high lil hfs element values and negative anomalies of ti ta nb and ba negative sr anomalies are observed in the lmp and trans rocks lil elements show overall positive correlations with k2o whereas different trends of sr and hfse vs k2o are defined by lmp trans and ks hks kam 87sr 86sr range from about 0 710 to 0 716 ks hks and kam rocks have similar 87sr 86sr values clustering around 0 710 lmp and trans rocks have the highest 87sr 86sr values geochemical and isotopic data reported for the most primitive italian potassic and ultrapotassic rocks support the hypothesis that the interaction between crustal and mantle reservoirs was a main process in the genesis of italian potassic magmatism simple mass balance calculations exclude however an important role of crustal assimilation during ascent of subcrustal magmas to the surface and indicate that the sources of central italy volcanics underwent contamination with fluids and or melts released by upper crustal material previously brought into the mantle by subduction processes different trends of incompatible elements vs k2o observed in the studied rocks suggest distinct metasomatic processes for the sources of the investigated magmas liquids derived by bulk melting of pelitic sediments are believed to be the most likely contaminants of the source of lmp rocks fluids or melts rich in ca sr and with high lile hfse value and sr isotopic composition around 0 710 are the most likely contaminant of the source region of ks hks and kam volcanics variations in cao na2o and ferromagnesian element abundances and ratios suggest that in some zones the mantle source of potassic magmas experienced partial melting with extraction of basaltic liquids prior to metasomatism

palaeoseismology review of the state of the art abstract historical seismicity provides only a partial indication of the seismotectonic character i e earthquake potential of a given region even in italy where a relatively long historical record exists available catalogues are generally unsatisfactory for this purpose fortunately strong earthquakes often leave geological evidence herein referred to as seismites that are mainly related to surface faulting folding or other deformation and occasionally to secondary ground failures e g landslides liquefaction features etc these features may be preserved and therefore palaeoseismological studies may detect and date them thereby permitting extension of knowledge beyond the local historical threshold up to 2000 years in the most fortunate cases this paper provides a summary of criteria which may aid in the identification of areas suitable for palaeo earthquake investigation historical seismicity and the presence of well developed tectonic geomorphic features are recognized as the most reliable criteria for identifying active faulting however lack of these characteristics cannot be considered conclusive evidence for lack of activity palaeoseismological techniques aim at identifying not only the obvious effects of surface faulting such as offset of young geologic units but also the more subtle tectonic or non tectonic features including liquefaction structures gravity features and coseismic uplift and or subsidence finally we discuss some questions that pertain to palaeoseismicity evaluation techniques among these are the reliability of the quaternary dating techniques the evaluation of the seismic energy released minimum magnitude and principally the unequivocal identification of a seismic origin for the considered geological structures

influence of temperature on the permeability of rocks changes in physical properties due to temperature increase have been investigated for three generically different types of rock marble sandstone and granite the hg porosity and permeability of the rocks were analysed the permeability of the specimens was determined during axial loading at a constant triaxial state of stress greater permeability changes were registered for rocks with compact structure and low porosity these types of rock are characterised by line contacts between the grains they are more sensitive to temperature increase pores with a radius greater than 500 nm increase due to the temperature influence with the permeability increasing considerably

petrology and mineralogy of wollastonite and melilite bearing paralavas from the central apennines italy small outcrops of wollastonite and melilite bearing pyrometamorphic rocks paralavas are found along the apennine chain in central italy at the localities of colle fabbri and ricetto these rocks have coarse to fine grained crystalline spotted and glassy textures the colle fabbri rocks have abundant and ubiquitous wollastonite with plagioclase clinopyroxene melilite is found only in the most ca rich and silica poor samples garnet perovskite quartz leucite silica rich glassy mesostasis and ocelli filled by calcite are present locally the ricetto rock is made up of wollastonite and melilite with minor clinopyroxene set in a glassy matrix with a few crystals of restitic quartz these rocks have variable contents of sio2 43 to 64 wt and cao 37 to 3 7 wt the latter decreases with increasing mgo al2o3 fe2o3 tot tio2 k2o sio2 and most trace elements excluding sr peculiar parageneses e g coexisting melilite and anorthite in the most silica poor samples abundance of wollastonite mineral compositions gehlenite rich melilite al ti and fe3 rich clinopyroxene al ti rich but fe poor garnet and major and trace element geochemistry suggest that the colle fabbri and ricetto rocks are not ultimately mantle derived but are the result of melting devolatilization and recrystallization of marly sediments 50 60 to 5 10 calcite with clay minerals quartz likely due to coal fires the 87sr 86sr and 143nd 144nd range from 0 70772 to 0 71190 and from 0 51223 to 0 51219 respectively again suggesting sedimentary protoliths of a mixed nature substantial chemical and isotopic differences between these samples and those from the roman magmatic province are highlighted

influence of the interval length of hydraulic packer systems on thermally induced pore pressure measurements in rock abstract during the past several decades hydraulic packer systems have generally been used to measure the thermally induced pore pressures in many in situ experiments in nuclear waste management programs the measured value using hydraulic packer system is a combined value of the pore pressures in the rock along the packer interval and not the pore pressure at the middle point the suitability of using the packer system measured value to represent the thermally induced pore pressure at the middle point of the packer interval needs to be assessed the accuracy of using hydraulic packer systems is examined in this paper using a coupled thermal hydraulic mechanical thm model for fully saturated conditions developed using the finite element program comsol the results indicate that there could be large errors in the measured values with the size of the error dependent on the size of the packer interval the variation of pore pressure gradient along that interval and the orientation of the packer measurement borehole to improve the accuracy of the measurement using packer systems the variation in pore pressure gradient along the packer interval should be small or if a substantial gradient variation is expected the length of the packer interval should be made as small as possible a packer interval with a length less than 0 5 m is suggested if a packer system has been installed with a large interval length in a location where a large pore gradient variation may exist calibration of any associated numerical model using this measurement should incorporate the packer measurement system the numerical results of this coupled thm model are in good agreement with the integration of a point heat source theoretical solution throughout the heater line

modelling seismites with a digital shaking table abstract soft sediment deformation structures induced by seismically triggered liquefaction and or fluidization seismites have been reproduced with a digital shaking table we have used natural sediments with variable granulometric ranges clay silt and sand and an earthquake simulator that is able to reproduce real tridimensional seismograms acceleration and pore pressure recording allowed us to follow liquefaction and or fluidization processes in unconsolidated sediments during earthquakes different types of seismites were produced by variations in the tested sedimentary column

analysis of thermally induced changes in fractured rock permeability during eight years of heating and cooling at the yucca mountain drift scale test analysis of thermally induced changes in fractured rock permeability during eight years of heating and cooling at the yucca mountain drift scale test j rutqvist 1 b freifeld 1 k b min 2 d elsworth 2 y tsang 1 earth sciences division lawrence berkeley national laboratory ms 90 1116 berkeley ca 947 20 usa department of energy and geo environmental engineering pennsylvania state university university park pa 16802 usa corresponding author tel 1 510 486 5432 fax 1 510 486 5432 e mail address jrutqvist lbl gov j rutqvist abstract we analyzed a data set of thermally induced changes in fractured rock permeability during a four year heating up to 200 c and subsequent four year cooling of a large volume partially saturated and highly fractured volcanic tuff at the yucca mountain drift scale test in nevada usa permeability estimates were derived from about 700 pneumatic air injection tests taken periodically at 44 packed off borehole intervals during the heating and cooling cycle from november 1997 through november 2005 we analyzed air permeability data by numerical modeling of thermally induced stress and moisture movements and their impact on air permeability within the highly fractured rock our analysis shows that changes in air permeability during the initial four year heating period which were limited to about one order of magnitude were caused by the combined effects of thermal mechanically induced stress on fracture aperture and thermal hydrologically induced changes in fracture moisture content at the end of the subsequent four year cooling period air permeability decreases to as low as 0 2 of initial and increases to as high as 1 8 of initial were observed by comparison to the calculated thermo hydro elastic model results we identified these remaining increases or decreases in air permeability as irreversible changes in intrinsic fracture permeability

pyrometamorphic processes at the magma hydrothermal system interface of active volcanoes evidence from buchite ejecta of stromboli aeolian islands italy pyrometamorphic ejecta erupted during recent paroxysmal explosions and hydrothermally altered volcanic and subvolcanic rocks from stromboli volcano aeolian islands italy were studied by combined polarizing microscopy electron microprobe scanning electron microscope x ray diffraction transmission electron microscope and whole rock inductively coupled plasma optical emission spectrometry mass spectrometry analysis the pyrometamorphic ejecta are compositionally heterogeneous at the macroand micro scale and are classified as buchites that is glass coupled with a high temperature low pressure modal mineralogy three distinct facies i e cordierite plagioclase mullite plagioclase palisade and tridymite clinopyroxene are recognized among the buchites whose bulk rock chemistry is compatible with aluminousto silica rich protoliths abundant mineral growth e g plagioclase palisades and clinopyroxene coronae occurs at the contact between the ejecta and the crystal rich host shoshonitic basalt which typically coats the pyrometamorphic blocks mineral constraints pseudoporphyritic microstructures plagioclase relict phenocrysts and major and trace element compositions strongly support the origin of the buchite ejecta as hydrothermally altered rocks from thevancori edifice a period of activity spanning 410 kyr which underwent high temperature low pressure contact metamorphism in the uppermost magmatic system of an active island arc volcano such as stromboli volcanic and subvolcanic rocks usually undergo alteration processes induced by acid sulphate hydrothermal systems the circulation of acidic fluids results in leaching of the stromboli rocks in the upper part of the volcano edifice and depending on the ph temperature and exposure time to the hydrothermal fluids production of different alteration facies the hydrothermally altered stromboli rocks show facies consistent with argillic to silicic alteration containing abundant hydrous sulphate and hydroxy sulphate minerals such as the alunite group minerals hexahydrite millosevichite pickeringite and kieserite the hydrothermally altered wall rocks heated by contact with the basaltic magma of the feeder dyke system of stromboli can easily undergo pyrometamorphic processes inducing partial melting and subsolidus crystallization of the volcanic protoliths this results in the development of buchite rocks at the magma hydrothermal system interface

the system mg2sio4 ca2sio4 caal2o4 naalsio4 sio2 one atmosphere liquidus equilibria of analogs of alkaline mafic lavas one atmosphere liquidus relationships in the system mg2sio4 fo ca2sio4 la naalsio4 ne caal2o4 ca sio2 sil are presented as analogs for alkaline mafic lavas liquidus diagrams are constructed from electron microprobe analyses of quenched liquids and coexisting mineral phases produced in melting experiments and they are depicted in terms of sub projections within the pseudo quaternary system fo la ne ca sil the ne and ca components are combined to create a normative feldspathoid component defined as ne ne ne ca liquidus relations at ne 0 5 from this study are compared to relations at ne 0 0 and 1 0 from previous studies in general liquidus temperatures decrease and positions of liquidus boundaries involving feldspathic phases shift toward the ne ca component as ne increases the pseudoinvariant points fo di pl mel l and fo pl mel sp l exist at ne 0 5 these equilibria between forsterite plagioclase melilite liquid are not present in the system when ne 1 0 because a boundary curve fo di ne l separates the plagioclase and melilite liquidus fields the liquidus diagrams provide useful analogs for the crystallization sequences of natural primary alkali olivine basalts basanitoids basanites olivine nephelinites olivine melilite nephelinites and olivine melilitites

thermal strain in a water saturated limestone under hydrostatic and deviatoric stress states abstract the present study is aimed at investigating the evolution of thermally induced bulk strain in a water saturated limestone blaubeuren at three different stress states three cylindrical rock samples are respectively loaded to a constant stress state 1 3 15 mpa 1 45 mpa 3 15 mpa 1 75 mpa 3 15 mpa at drained conditions in a conventional triaxial rock deformation apparatus before the sample temperature is cycled between 30 c and defined levels up to 120 c strain measurements are performed by one circumferential and two axial extensometers irreversible strain in both the lateral and axial sample directions are measured after each temperature cycle indicating permanent increases in diameter and in length the measured bulk strain is separated into different strain components related to 1 initial stress loading 2 reversible thermal expansion and contraction of rock matrix and 3 some residual strain the magnitudes of the residual strain increase with increasing deviatoric stress 1 3 in the lateral direction but decrease with increasing deviatoric stress in the axial direction the derived matrix thermal expansion coefficients range from 6 10 6 c 1 to 1 8 10 5 c 1 and from 9 10 6 c 1 to 1 5 10 5 c 1 respectively in the axial and lateral directions and present lower values at higher deviatoric stresses microstructural analyses evidence tensile cracks which are interpreted to have been induced during the temperature cycles these cracks have the potential to offset matrix thermal expansion yielding lower matrix thermal expansion coefficients at higher deviatoric stresses

deciphering the sedimentological imprint of paleoseismic events an example from the aptian codo formation northern brazil abstract a stratigraphic horizon bearing several styles of soft sediment structures occurs sandwiched within entirely undisturbed deposits in the lacustrine codo formation aptian located in the eastern part of the grajau basin northern brazil these deposits show a variety of sedimentary features distinguished according to their deformation style as follows from bottom to top a zone 1 consisting of widespread molar tooth structures i e fine grained spar filled cracks that are interconnected with small scale faults fissures and stylolites inclined at a high angle to bedding b zone 2 represented by complex convolute folds with lateral gradation of smooth synclines and anticlines into isoclinic folds and internal layers that retain the normal bedding features recumbent folds nappe folds with associated thrust faults pseudonodules and mound and sag structures c zone 3 consisting of normal faults and fissures that are vertical to near vertical show ragged morphology with small delicate peaks taper both downward and upward after a few centimeters and are associated with large up to 2 5 m long collapsed boulders and d zone 4 characterized by shales with irregular convolute folds these deformation zones are interpreted to reflect sediment rheology and alternating periods of sediment accumulation and deformation under the influence of synsedimentary seismic events as suggested mostly by 1 occurrence between undeformed deposits 2 lateral correlation for several kilometers of distance 3 similarity with other features formed in areas affected by seismic activity 4 presence of structures attesting to sediment deformation in an unconsolidated to semi consolidated state and 5 complex association of brittle and ductile deformation structures hence zone 1 records small scale cracking and faulting of early cemented cohesive deposits zone 2 is dominated by ductile deformation structures formed on water saturated unconsolidated sediments probably as a reflex of compressional stress zone 3 records a change in tectonic style to dominantly distension as evidenced by the horizon with normal faults finally zone 4 shows structures attributed to ductile deformation of water saturated muds which was probably formed during the same episode of deformation responsible for the faults and fissures in zone 3 this succession of deformation events appears to be consistent with transtensional and compressional shear stresses during the sedimentary evolution of the grajau basin

natural pseudowollastonite crystal structure associated minerals and geological context abstract pseudowollastonite an extremely rare constituent of ultrahigh temperature combustion metamorphic and igneous rocks has been found as a rock forming mineral in ca rich paralava veins of nabi musa fossil mud volcano dead sea area pseudowollastonite bearing paralavas are the products of combustion metamorphism associated with spontaneous burning of methane the melt began to crystallize at 1480 1500 c about the ambient pressure pseudowollastonite enters two mineral assemblages 1 rankinite larnite nagelschmidtite wollastonite 1 t gehlenite rich melilite ti rich andradite cuspidine and fluorapatite 2 parawollastonite 2 m wollastonite 1 t gehlenite rich melilite ti rich andradite fluorellestadite in this study we present the first single crystal structure determination of natural pseudowollastonite pseudowollastonite from nabi musa dome is stoichiometric casio 3 and belongs to the most widespread four layer polytype a 6 83556 10 a b 11 86962 18 a c 19 6255 3 a 90 6805 13 v 1592 21 4 a 3 space group c 2 c we argue that pseudowollastonite is so scarce in nature because its formation requires joint action of several uncommon factors availability of hot melts of t 1200 c that bear free calcium but are poor in mg and fe mostly as fe 3 and their crystallization in the shallow crust followed by quenching

analysis of soft sediment deformation structures in neogene fluvio lacustrine deposits of caybagi formation eastern turkey during the neogene both strike slip and extensional regimes coexisted in eastern turkey and a number of fault bounded basins associated with the east anatolian fault system developed the caybagi formation late miocene early pliocene deposited in one of these basins consists of fluvio lacustrine deposits numerous soft sediment deformation structures are encountered in this formation particularly in conglomerates medium to coarse grained tuffaceous sandstones and claystones folded structures slumps convolute laminations and simple recumbent folds water escape structures intruded sands internal cusps interpenetrative cusps and sand volcanoes and load structures load casts pseudonodules flame structures and pillow structures these structures are produced by liquefaction and or fluidization of the unconsolidated sediments during a seismic shock consequently the existence of seismically induced deformation structures in the caybagi formation and the association with a neogene intraformational unconformity growth faults and reverse faults in the caybagi basin attest to the tectonic activity in this area during the late miocene and early pliocene the east anatolian fault system in particular the uluova fault zone is the most probable seismogenic source earthquakes with a magnitude of over 5 in the richter scale can be postulated

palaeochannels in mine workings in the high hazles coal westphalian b nottinghamshire coalfield england palaeochannels have numerous deleterious effects on coal mining including the formation of washouts and their detection and delineation in the subsurface is of paramount importance a palaeochannel system in the roof of the high hazles coal westphalian b at gedling colliery nottinghamshire is described the roof strata of this seam are interpreted as the deposits of a lacustrine delta complex formed on an upper delta plain with the palaeochannels constituting minor deltaic distributaries the lacustrine delta front deposits consist of a coarsening upwards sequence of siltstones and sandstones which form a sheet like body of coalescing distributary mouth bars that were laid down by friction dominated effluents the distributary channels were filled by a variety of processes giving rise to complex channel deposits bedload deposition of sand on bars collapse and sloughing of channel banks and deposition of silts and muds from suspension were important mechanisms the nature of the deposits reflects the mode of channel abandonment rather than equilibrium channel processes overbank flood deposits and prodelta lacustrine mudstones are also described from the high hazles roof based on this study criteria are suggested that may enable the successful detection and delineation of palaeochannels in mine workings elsewhere

comment on melluso et al 2003 reported data and interpretation of some wollastonite and melilite bearing rocks from the central apennines of italy two distinct occurrences of wollastonite and melilite bearing rocks from ricetto and colle fabbri which are located in the central italy apennine range are referred to as paralavas generated by melting and recrystallization of marly sediments likely due to coal fires by melluso et al 2003 we submit data demonstrating that these conclusions are incorrect ricetto is clearly pyrometamorphic as described by capitanio et al 2001 2004 colle fabbri is clearly an igneous outcrop as described in stoppa 1988 it is quite different in scale field relationships and chemistry and thus ricetto is irrelevant to its petrogenesis the sediment mixing model of melluso et al 2003 does not relate to the colle fabbri field data furthermore the ricetto miocene flysch country rock and the colle fabbri enclosing pliocene clays were not analyzed by melluso et al 2003 a limestone shale mixing calculation using sr and nd isotopic data in melluso et al 2003 tables 3 4 and a 1 4 3nd 1 4 4 nd ratio of 0 51213 for apennine shales op cit p 1297 fails to account for the colle fabbri samples which remain well clear of the hypothetical mixing line rocks of mantle origin including micaceous kimberlites and western australia lamproites plot in the variation field of colle fabbri and regionally associated igneous rocks colle fabbri is but one of a series of similar igneous melilite bearing and carbonatite occurrences that constitute the intramontane ultra alkaline province of central italy iup although colle fabbri does have unique features as do other of these occurrences stoppa et al 2003

mechanisms and controls on the formation of sand intrusions sandstone intrusions are found in all sedimentary environments but have been reported most commonly from deep water settings they also appear to be more frequently developed in tectonically active settings where applied tectonic stresses facilitate development of high fluid pressures within the sediments a variety of mechanisms have been cited as triggers for clastic intrusions these include seismicity induced liquefaction application of tectonic stresses excess pore fluid pressures generated by deposition related processes and the influx of an overpressured fluid from deeper within the basin into a shallow sand body the formation of sandstone dykes and sills is investigated here by considering them as natural hydraulic fractures when the seal on an unconsolidated overpressured sand body fails the resulting steep hydraulic gradient may cause the sand to fluidize the fluidized slurry can then inject along pre existing or new fractures to form clastic intrusions the scale and the geometry of an intrusive complex is governed by the stress state depth and pre existing joints or faults within the sedimentary succession as well as the nature of the host sediments for the simplest tectonic setting where the maximum stress in a basin is vertical gravitational loading small irregular intrusions commonly result in the formation of sills at shallow depths within a few metres of the surface whereas at greater depth dykes and sills forming clastic intrusion networks are more typical a simple relationship is derived to calculate the maximum burial depth at which a dyke sill complex forms as a function of the source bed to sill height the bulk density of the surrounding sediments and the ratio of the vertical to horizontal effective stresses k 0 when applied to three examples of large scale dyke sill complexes developed within paleocene and eocene deep water reservoir sand bodies of the north sea maximum burial depths in a range of 375 to c 500 m 450 700 m and 550 850 m are estimated for intrusion of each of the three complexes

variations of connected porosity and inferred permeability in a thermally cracked granite connected porosity volume and throat diameter were measured in granitic samples with different porosity structures heated from 20 to 700 c three types of microstructures are recognized from scanning electron microscopy sem analysis 1 a crack network of transgranular cracks with few intersections 2 a pipe network of intragranular and intergranular tubes with high connectivity 3 a mixed structure of transgranular cracks connected by intragranular tube structures calculations predict a decrease of permeability through crack and mixed networks between 50 and 400 c followed by a sharp increase at higher temperatures the decrease in permeability is associated predominantly with the decrease in throat diameter whereas the increase in both throat diameter and the porosity volume account for the temperature rise only small variations of the permeability are predicted for the pipe network

oriented clastic dike swarms as indicators of paleoslope an example from the upper cretaceous nanaimo group canada abstract an impressive oriented clastic dike swarm 165 dikes occurs within 3 25 m of strata of a submarine fan turbidite succession of the upper cretaceous nanaimo group british columbia the dikes are remarkably parallel in orientation are consistently subvertical and strike southwest slump fold vergence paleocurrent indicators and other evidence indicate that local paleoslope strike was northwest with a downslope direction to the southwest thus the clastic dikes strike downslope indicating that extension occurred perpendicular to the regional downslope direction not parallel as generally expected two possible models are proposed 1 rapid downslope compression caused by sudden loading perhaps due to slumping events or deposition of thick turbidity current beds this downslope compression caused minor extension perpendicular to the downslope direction resulting in small extensional joints that accommodated clastic injection from buried overpressured sands 2 chaotic sedimentary breccias laterally adjacent to the dike swarm formed as part of a large slumping event which created a local slump channel minor slumping into the main channel from the sides caused extension parallel to the channel margin slope and formation of the clastic dikes parallel to the channel margin but perpendicular to the regional slope oriented clastic dike swarms may represent a new type of paleoslope indicator but they may be created by a number of processes and should therefore be used only in conjunction with supporting evidence

clastic dike swarms and the structural evolution of the foreland fold and thrust belt of the southern andes clastic dike swarms are intruded into a cenozoic foreland fold and thrust belt in southern chile the dike material consists of sandstone and conglomerate with clasts as much as 25 cm in diameter brecciated wall rocks are also found in the clastic matrix the dikes often exceed 50 cm in width and hundred of metres in length in outcrop and are oriented overwhelmingly transverse to fold axes and parallel to cross joints the dike swarms are concentrated near the toe of major thrusts where they are found injected into the hanging wall a regional axial planar spaced cleavage is developed in the clastic dikes and sills clearly postdating injection of clastic material dike injection postdates at least the initiation of extension fractures the cross joint set within the swarms the dike intrusions represent as much as 20 extension parallel to fold axes in addition to several percent extension represented regionally by the cross joints the structural features of the dike swarms and their geometric relationship to other structures suggest rapid single phase injection the arrival of the front edge of a thrust on an already highly overpressured sedimentary sequence would cause an instantaneous increase in the overburden pressure and therefore could result in injection of a dense slurry of wet coarse sediments along preexisting planes of weakness field relationships of mesoscopic structures suggest the following evolution cross joint development incipient cleavage development initiation of thrusting and buckling clastic dike injection regional spaced cleavage development and associated late stage tightening of folds

possible earthquake induced soft sediment faulting and remobilization in pennsylvanian alluvial strata southern new brunswick canada braided river sheetflood and playa lake sediments of the tynemouth creek formation lower pennsylvanian show superficial synsedimentary faulting and subsurface post depositional sediment remobilization a prominent palaeosol has been offset 90 cm on two faults movement on which clearly preceded deposition of the overlying beds seventeen to 25 m below this horizon large load structures upward branching siltstone intrusions and three types of sandstone dike are recognised intrusion occurred on several occasions at different depths of burial and was the result of rapid probably earthquake induced dewatering this interpretation is supported by the location of the study area only a few kilometres to the north of the cobequid chedabucto fault on which major strike slip movement occurred during the pennsylvanian

rare earth elements in limestone marlstone couplets from the albian cenomanian cismon section venetian region northern italy assessing ree sensitivity to environmental changes abstract we have studied the ree distribution through the albian cenomanian interval of a stratigraphic succession cismon section scaglia variegata formation venetian prealps consisting of rhythmically alternating carbonate rich and carbonate poor strata which are the sedimentary expression of systematic variations of surface fertility and bottom water redox conditions in the depositional basin limestone semicouplets show seawater like shale normalized patterns hree enriched with negative ce anomalies and high er nd ratios indicating a clear dependence on the ree chemistry of surface seawaters marlstones and shales exhibit flatter patterns more moderate ce anomalies and low er nd good correlations between er nd ce ce and mn suggest that superimposed on ree signatures imparted by detrital and biogenic phases the ree composition shows evidence of their sensitivity to palaeoredox conditions resulting in ree fractionation and ce cycling ree data are consistent with results from previous stratigraphic and geochemical major and trace elements investigations in reflecting palaeoenvironmental conditions rhythmically varying from efficiently mixed seawater during the limestone deposition to oxygen depleted bottom waters at the time of marlstone deposition

interaction between ultrapotassic magmas and carbonate rocks evidence from geochemical and isotopic sr nd o compositions of granular lithic clasts from the alban hills volcano central italy abstract magma carbonate rock interaction is investigated through a geochemical and sr nd o isotope study of granular lithic clasts ejecta from the alban hills ultrapotassic volcano central italy some samples group 1 basically represent intrusive equivalents of alban hills magmas a few samples group 2 are ultramafic have high mgo 30 to 40 wt and 18o and originated by accumulation of mafic phases that crystallised from ultrapotassic melts during assimilation of dolomitic rocks group 3 ejecta consist of dominant k feldspar and show major element compositions similar to phonolites which however are absent among the alban hills volcanics finally another group group 4 contains corroded k feldspars surrounded by a microgranular to porphyritic matrix made of igneous minerals k feldspar foids clinopyroxene phlogopite plus wollastonite garnet and some cuspidine group 4 ejecta are depleted in sio2 and enriched in cao with respect to group 3 the analysed ejecta have similar 143nd 144nd 0 51204 0 51217 as the alban hills lavas whereas 87sr 86sr 0 70900 0 71067 is similar to lower whole rocks 18o ranges from 7 0 to 13 2 reaching maximum values in ultramafic samples a positive correlation with cao is observed in single rock groups large ion lithophile element lile abundances and ree fractionation are generally high and extreme values of th u and lree are found in some group 3 and group 4 rocks mineralogical petrological and geochemical data reveal extensive interaction between magma and carbonate wall rocks involving both dolostones and limestones these processes had dramatic effects on magma compositions especially on phonolites which were transformed to foidites evidence of such a process is found in group 4 samples in which k feldspar is observed to react with a matrix that represents strongly undersaturated melts formed by interaction between silicate magma and carbonates trace element data also testify to a very important role for f co2 h2o s fluids during magma wall rock interaction fluid transfer was responsible for extreme enrichments in th u and lree especially observed in group 3 and group 4 rocks implications of these processes for potassic magma evolution in central italy are discussed

soft sediment deformation structures interpreted as seismites in middle late pleistocene aeolian deposits apulian foreland southern italy abstract soft sediment deformation structures in middle late pleistocene deposits of torre san gennaro brindisi southern italy have been analysed from a morphologic point of view the deformational structures are represented by deformed cross bedding and large injection structures they are restricted to aeolian sediments and the mechanism of deformation is related to liquefaction and or fluidization processes the liquefaction and or fluidization processes have been interpreted as seismic induced after consideration of all other possible trigger agents the discussion about the possible source areas of the palaeoseismic event was carried out through the analysis both of the general magnitude distance relations and the main structural features of the study zone in conclusion we consider the key criteria for trigger mechanism interpretation of soft sediment deformation structures in aeolian deposits and the actual feasibility of using aeolian sediments for the palaeoseismic studies

deposition and deformation of fluvial lacustrine sediments of the upper triassic lower jurassic whitmore point member moenave formation northern arizona abstract the stratigraphic section of the upper triassic lower jurassic whitmore point member of the moenave formation at potter canyon arizona comprises c 26 m of gray to black shales and red mudstones interbedded with mainly sheet like siltstones and sandstones these strata represent deposition from suspension and sheetflow processes in shallow perennial meromictic to ephemeral lakes and on dry mudflats of the terminal floodout of the northward flowing moenave stream system the lakes were small as indicated by the lack of shoreline features and limited evidence for deltas changes in base level likely forced by climate change drove the variations between mudflat and perennial lacustrine conditions lenticular sandstones that occur across the outcrop face in the same stratigraphic interval in the lower part of the sequence represent the bedload fill of channels incised into a coarsening upward lacustrine sequence following a fall in base level these sandstones are distinctive for the common presence of over steepened bedding dewatering structures and less commonly folding deformation of these sandstones is interpreted as aseismic due to the lack of features typically associated with seismicity such as fault graded bedding diapirs brecciated fabrics and clastic dikes rapid deposition of the sands on a fluid rich substrate produced a reverse density gradient that destabilized and potentially fluidized the underlying finer grained sediments this destabilization allowed synsedimentary subsidence of most of the channel sands accompanied by longitudinal rotation and or ductile deformation of the sand bodies

relationships between ultrapotassic and carbonate rich volcanic rocks in central italy petrogenetic and geodynamic implications the pleistocene intra apennine volcanic iav centres occurring east of the potassium rich roman comagmatic province show variable petrological and geochemical composition some rocks have a strongly undersaturated ultrapotassic kamafugitic affinity with k2o na2o 8 20 whereas the rocks from the southern center of mt vulture are still strongly undersaturated in silica but are enriched in both na2o and k2o with k na around unity carbonate rich pyroclastic rocks believed to represent carbonatitic magmas are found in the iav centers kamafugites have high abundances of lile and high lile hfse ratios and their incompatible element patterns resemble closely those of ultrapotassic rocks from the adjoining roman province the vulture volcanics also display high contents of lile but their lile hfse ratios are intermediate between intraplate alkaline rocks and kamafugites the carbonate rich rocks exhibit an exotic mineralogy and high enrichments in lile which speaks for a carbonatitic affinity however they have similar incompatible element patterns but consistently lower abundances of almost all the elements than the associated silicate volcanics these data favour the hypothesis that the iav carbonate rocks may represent mixtures of silicate magmas and geochemically depleted carbonate material the sedimentary carbonates that crop out extensively along the apennine chain may be the source of barren carbonate material overall geochemical data of iav centres and of the rocks from the roman province display strong geochemical and isotopic evidence of being generated in an upper mantle that was modified by addition of upper crustal material brought down by subduction processes a possible exception is represented by mt vulture which however occurs east of the main axis of the apennines on the western margin of the foreland adria plate the occurrence of strongly undersaturated alkaline rocks requires magma generation at high pressures and xco2 this is in agreement with the hypothesis that subduction processes under the apennines occurred by consumption of poorly hydrated thinned or delaminated continental crust

recognition of trigger mechanisms for soft sediment deformation in the pleistocene lacustrine deposits of the santʻarcangelo basin southern italy seismic shock vs overloading abstract the lacustrine deposits of the san lorenzo cycle belong to the infill succession of the sant arcangelo basin a pliocene to pleistocene satellite basin developed close to the front of the south apennines thrust belt the lower to middle pleistocene lacustrine succession is made up of siltstone and claystone interbedded with sandstone carbonate and volcaniclastic beds arranged in fining upward sequences the upper to middle part about 50 m thick of the succession about 200 m thick has been investigated in detail in the depocentral sector of the lacustrine basin here soft sediment deformation structures occur in fine grained sandstone and claystone alternations and show a wide morphological variability deformed laminations slumps load structures large vertical water escape structures and neptunian dykes their formation occurred during and after sedimentation with different mechanisms of deformation some structures are related to liquefaction and fluidization processes viscous fluid behaviour while others occurred when sediment had already undergone lithification and its behaviour was plastic and or brittle facies analysis and detailed morphologic study of the soft sediment deformation structures indicate that the main trigger agents for deformation were seismic shocks and overloading induced by sudden deposition of coarser sediments on clays due to the arrival of density currents thus the soft sediment deformation structures provide a continuous record of the tectonic and sedimentary processes that acted in the lacustrine basin from sedimentation until diagenesis

mid carboniferous diversification of continental ecosystems inferred from trace fossil suites in the tynemouth creek formation of new brunswick canada we report skolithos scoyenia and mermia ichnofacies from sub humid tropical fluvial megafan deposits in the lower pennsylvanian tynemouth creek formation of new brunswick canada and discuss their evolutionary and palaeoecological implications especially regarding the colonization of continental freshwater terrestrial environments the skolithos ichnofacies comprises annelid arthropod spreite in the upper storey of a fluvial channel the scoyenia ichnofacies comprises tetrapod tracks arthropleurid trackways and shallow annelid arthropod burrows in active abandoned fluvial channels and rapidly aggrading levees splays in proximal interfluve areas the mermia ichnofacies comprises abundant xiphosuran trackways along with diverse traces of other arthropods annelids mollusks and fish in shallow freshwater lakes ponds and coastal bays in slowly aggrading distal interfluve areas transitional mermia scoyenia ichnofacies comprise tetrapod mollusk and annelid arthropod traces in coastal bay deposits on the distal edge of the megafan these trace fossil suites 1 provide the clearest documentation yet of the mid carboniferous diversification event when tropical continental environments became more densely populated 2 suggest that euryhaline visitors xiphosurans microconchids and other taxa from open marine settings played a key role in this episode of freshwater colonization and 3 provide empirical support for the deja vu effect the evolutionary concept that new or empty ecospace recurrent in spatially and temporally variable environments is colonized by simple ichnocoenoses

diverse tetrapod trackways in the lower pennsylvanian tynemouth creek formation near st martins southern new brunswick canada abstract newly discovered tetrapod trackways are reported from eight sites in the lower pennsylvanian tynemouth creek formation of southern new brunswick canada by far the most abundant and well preserved tracks comprise pentadactyl footprints of medium size 32 53 mm long with slender digits and a narrow splay mostly

slags from ruda śląska poland as a large scale laboratory for the crystallization of rare natural rocks melilitolites and paralavas abstract zinc and lead smelting slags from ruda l ska are unique in their chemistry and phase composition which resemble rare natural rocks such as paralavas and melilitolites moreover considering its size we can treat a pyrometallurgical slag dump as a geological body in slags from ruda l ska the assemblage melilite pseudowollastonite wollastonite plagioclase was discovered in glassy slag high temperature experiments were performed to determine the temperature conditions and to reconstruct the crystallization of such an assemblage two slag samples were subjected to complete melting and crystallization with controlled thermal gradients of 53 25 c h 15 20 c h and 7 60 c h the results showed that crystal nucleation started at temperatures of 1250 1300 c depending on the fluctuations of chemical composition in both samples the thermal gradient only partly influenced the phase differentiation being rather responsible for the disappearance of the primary glass moreover even slight differences in chemical composition resulted in changes in phase assemblages under the same temperature conditions mll gls vs pwol pl mll gls it was proven that it is due to the combination of undercooling conditions and solidus dependences in the akermanite gehlenite solid solution the occurrence of such phenomena should be considered in natural rocks with similar composition in the case of the ruda l ska slags it explains the dominance of glassy slag in that location the experiments gave us an opportunity to observe and precisely analyze crystallization in real time providing new insights into the creation of slags and their natural analogues however the study has also shown that possible variations of the original crystallization should always be assessed

combustion metamorphism of bituminous sediments and the formation of melts of granitic and sedimentary composition during combustion metamorphism i e the heating of sediments rich in organic matter by spontaneous subsurface combustion temperatures obtained are frequently high enough to cause partial or total melting of the original rocks these melts are of particular geochemical interest because at lower temperatures their composition closely simulates that of granitic and at higher temperatures that of common sedimentary rocks at the california localities studied here the parent rocks are mainly bituminous mudstones with smaller amounts of diatomites and phosphorites and lesser dolomites limestones shales and cherts it is estimated that rock melting started below 1000 c the first partial melts correspond to a melt fraction of about 5 have a constant composition which is controlled by the eutectic of the dominant mudstones and are undistinguishable in major and trace element composition from common s type granites compared with the original rocks these melts are enriched in sio2 al2o3 k2o na2o as well as in ta hf zr th and ree and are depleted in all other elements studied the only difference between these low temperature melts and granitic ones is their oxygen isotope composition which is that of the sedimentary parent rocks these melts intruded the country rocks as sills and dikes and cooled to glassy rocks simulating obsidians as temperatures rose the melts changed composition and left the magmatic field at the highest temperatures in excess of 1650 c their composition equals that of the original sediments from which they are derived except for volatile components such as h2o and co2 these melts formed intrusive bodies mainly stocks up to several kilometers across on cooling these melts formed fine grained but holocrystalline rocks the dominant minerals of which are cristobalite and tridymite calcic plagioclase cordierite wollastonite gehlenite andradite and apatite where the parent rocks included phosphorites two immiscible melts formed an emulsion in which droplets of apatitic composition are surrounded by a silicate melt almost devoid of p2o5

vegetation ecology of early pennsylvanian alluvial fan and piedmont environments in southern new brunswick canada abstract the vegetation ecology of pennsylvanian upland dryland regions is poorly known despite its evolutionary significance here fossil plant assemblages are described from well drained alluvial fan piedmont deposits in the uppermost boss point and tynemouth creek formations late yeadonian langsettian southern new brunswick beds record the northward building of a large alluvial fan complex over alluvial plain deposits in response to near continuous sourceland uplift proximal alluvial fan environments characterized by sheetfloods and braided streams were dominated by large cordaitalean trees medullosan pteridosperms ferns and calamiteans distal alluvial fan environments where braided stream and levee splay sedimentation predominated were covered by similar vegetation together with lycopsids in localized poorly drained depressions calamitean thickets were particularly widespread in rapidly aggrading settings on the distal fan well drained alluvial plains beyond the fan toe were characterized by axial braided rivers containing cordaitalean trunks transported from proximal settings piedmont vegetation is otherwise poorly resolved all studied plant assemblages are of low to medium diversity and dominated by the remains of a single group cordaitalean seed plants such dominance diversity characteristics together with the presence of charcoal the product of wildfire imply that pennsylvanian upland dryland vegetation experienced water stress and that the seed habit was integral to successful colonization

quaternary tectonics in a passive margin marajo island northern brazil marajoisland is located in a passive continental margin that evolved from rifting associated with the opening of the equatorial south atlantic ocean in the late jurassic early cretaceous period this study based on remote sensing integrated with sedimentology as well as subsurface and seismographic data available from the literature allows discussion of the significance of tectonics during the quaternary history of marginal basins results show that eastern marajoisland contains channels with evidence of tectonic control mapping of straight channels defined four main groups of lineaments i e nne ssw ne sw nw se and e w that parallel main normal and strike slip fault zones recorded for the amazon region additionally sedimentological studies of late quaternary and holocene deposits indicate numerous ductile and brittle structures within strati graphic horizons bounded by undeformed strata related to seismogenic deformation during or shortly after sediment deposition this conclusion is consistent with subsurface bouguer mapping suggestive of eastern marajoisland being still part of the marajograben system where important fault reactivation is recorded up to the quaternary together with the recognition of several phases of fault reactivation these data suggest that faults developed in association with rift basins might remain active in passive margins imposing important control on development of depositional systems copyright 2007 john wiley sons ltd

the sedimentary record of carboniferous rivers continuing influence of land plant evolution on alluvial processes and palaeozoic ecosystems abstract evidence from modern rivers and the deep time geological record attests to the fundamental importance of plant life for the construction of physical habitats within fluvial environments data from an extensive literature review and original fieldwork demonstrates that many landforms and geomorphic features of modern river systems appear in the palaeozoic stratigraphic record once terrestrial vegetation had adopted certain evolutionary advances for example stable point bars are associated with the onset of rooted plants in the siluro devonian and avulsive and anabranching fluvial systems become common at the same time as extensive arborescent vegetation in the carboniferous in this paper we demonstrate a correlation between the diversification of physical fluvial environments and the expansion of terrestrial fauna and flora with an emphasis on the culmination of these trends within carboniferous alluvial systems many extrinsic factors have been considered as possible controls on the evolutionary timelines of terrestrialization for organisms however a fundamental prerequisite for achieving terrestrial biodiversity was the variety of physical habitats especially riparian systems available for newly evolved organisms in association with abundant lowland meandering systems the widespread appearance across carboniferous alluvial plains of fixed channel and anabranching reaches created further physical landforms for colonization and would have promoted increasingly complex hyporheic flow regimes furthermore the associated increase in arborescent vegetation and supply of large woody debris to inland and coastal rivers would have created a wealth of microhabitats for continental organisms we argue that the expanding extent and diversity of physical alluvial niches during the palaeozoic is an underappreciated driver of the terrestrialization of early continental life the study of the deep time fossil and stratigraphic record also illustrates that vegetation is a fundamental prerequisite for the creation of biogeomorphic alluvial landforms and physical habitats and microhabitats

sand injectites from source to emplacement an example from the miocene age frimmersdorf seam garzweiler open cast mine lower rhine embayment

interstratal dewatering origin for polygonal patterns of sand filled cracks a case study from late proterozoic metasediments of islay scotland sand filled cracks from the lower fine grained quartzite of dalradian late proterozoic age on the island of islay western scotland may be divided into two main types both of which form orthogonal and non orthogonal closed patterns on bedding surfaces type 1 cracks are short and lenticular in cross section contain sand which had been injected downwards and are found on the bottoms of cross laminated sandstone beds type 2 cracks cut several beds and preserve evidence of upward flow of water saturated sand both types of crack developed through the interstratal intrusion of water saturated sand into shrinkage cracks in mud or muddy sand not as previously thought as a result of sub aerial desiccation or sub aqueous cracking of the sediment surface synaeresis these cracks likely resulted from layer parallel contraction caused by compaction of mudstone layers during burial seismic shock may have provided the trigger for the preferential development of polygonal crack patterns in these layers instead of the more usual small scale dewatering structures from a detailed comparison with published descriptions of filled cracks from a number of different geological environments it is concluded that interstratal cracking is a mechanism which rivals sub aerial desiccation in importance and is more common in the geological record than is currently realized

depositional history of the eocene chumstick formation implications of tectonic partitioning for the history of the leavenworth and entiat eagle creek fault systems washington the chumstick basin opened as an extensional half graben prior to 51 ma and was subsequently modified by two episodes of tectonic partitioning of drainage prior to basin deformation initially westward flowing fluvial systems formed a unified depositional system with the swauk basin tectonic partitioning of drainage at 51 49 ma and at 44 42 ma was controlled by localized uplift on the leavenworth lfz eagle creek ecfz and entiat efz fault zones and led in each instance to the truncation of regional depositional systems modification and reversal of paleoflow and internal drainage relief on the lfz at 51 49 ma may be the result of isostatic uplift of the extensional footwall producing the swauk and chumstick basins as a pair of west facing half grabens the earliest convincing evidence for the onset of oblique slip in the region is at about 48 ma folding in the swauk basin or about 44 42 ma probable transpressive uplift at left stepping bends of the lfz development of a transtensional step over basin between the ecfz and efz horsetail splays in the ecfz and possible flower structures in the lfz and ecfz in the chumstick basin each episode of tectonic partitioning was followed by proximal onlap and overtopping of fault zones to reestablish regional flow systems the chumstick formation was deformed by dextral transpression between 37 34 ma and is unconformably overlain by the oligocene wenatchee formation the chumstick basin is an example of an extensional basin modified by subsequent strike slip tectonics thus caution should be used in applying idealized basin models