origin of limestone conglomerates in the choson supergroup cambro ordovician mid east korea abstract the choson supergroup cambro ordovician of mid east korea consists mainly of shallow marine carbonates and contains a variety of limestone conglomerates these conglomerates are largely comprised of oligomictic rounded lime mudstone clasts of various size and shape equant oval discoidal tabular and irregular and dolomitic shale matrices most clasts are characterized by jigsaw fit mosaic disorganized or edgewise fabric and autoclastic lithology each conglomerate layer is commonly interbedded with limestone dolomitic shale couplets and occasionally underlain by fractured limestone layer capped by calcareous shale limestone conglomerates in the choson supergroup consist of 1 disorganized polymictic conglomerate cd 2 horizontally stratified conglomerate cs 3 mosaic conglomerate cm and 4 disorganized edgewise oligomictic conglomerate cd e these conglomerates are either depositional cd and cs or diagenetic cm and cd e in origin diagenetic conglomerates formed under the conditions of 1 alternating deposition and preservation of carbonate rich and carbonate poor layers and 2 early differential cementation of carbonate rich layers in situ fragmentation may result from brittle fracturing and ductile deformation due to compaction and dewatering enhanced by dissolution processes fluidization is promoted by the overlying impermeable calcareous shale beds and has probably reinforced in situ fragmentation of the underlying limestone beds in situ fragmentation and rounding process is important whereby earlier semiconsolidated portions of limestone are incorporated into the still fluid portion which can be termed autoconglomeration process a synthesis of 145 beds of limestone conglomerates in the choson supergroup suggests that less than about 7 of the conglomerate layers 10 145 are depositional whereas the rest more than 93 135 145 are identified as diagenetic conglomerates the common occurrence of diagenetic conglomerates warrants further study on limestone conglomerates elsewhere in the world

formal subdivision of the quaternary system period past present and future abstract the quaternary system period represents the past 2 58 million years and is officially subdivided into the pleistocene and holocene series epochs with the base of the holocene assigned an age of 11 700 calendar years before ad 2000 the two lowest stages of the pleistocene the gelasian base 2 58 ma and the calabrian base 1 80 ma have been ratified and these effectively constitute the lower pleistocene subseries all other official subdivisions are pending for the middle pleistocene subseries three candidate global boundary stratotype sections and points gssps are under consideration the valle di manche in calabria and montalbano jonico in basilicata both in southern italy and the chiba section in japan the matuyama brunhes chron boundary 773 ka serves as the principal guide for the base of the middle pleistocene the base of the upper pleistocene subseries is generally agreed to coincide approximately with that of the last interglacial marine isotope substage 5e 130 ka the fronte section near taranto in southern italy represents a possible candidate gssp but an antarctic ice core might also serve this purpose a tripartite subdivision of the holocene with subseries stage boundaries at 8200 and 4200 years b p is also under consideration additional fine scale formal subdivision of the quaternary is being explored with the last glacial maximum serving as a test case the anthropocene is both an informal and undefined interval of time that includes the present day its duration formal informal status rank and method of definition are all under debate with one suggestion that it be defined as a formal unit beginning with the world s first nuclear bomb explosion on july 16th 1945 suggested and proposed gssps are compared and critiqued the history leading to ratification of the quaternary period in 2009 is examined drawing upon published and unpublished material

nonlinearity in rock evidence from earth tides the earth is sinusoidally stressed by tidal forces if the stress strain relation for rock is nonlinear energy should appear in an earth tide record at frequencies which are multiples of those of the larger tidal lines an examination of the signals to be expected for different nonlinear deformation laws shows that for a nonlinear response without dissipation the largest anomalous signal should occur at twice the forcing frequency whereas for nonlinear laws involving dissipation cusped hysteresis loops the anomalous signal will be greatest at 3 times this frequency the size of the signal in the dissipative case depends on the amount by which dissipation affects the particular response being measured for measurements of strain tides this depends on whether dissipation is assumed to be present throughout the earth or localized around the point of measurement an analysis of 5 7 years of strain tide records from pinon flat california shows a small signal at twice the frequency of the largest m2 tide most of the observed signal can be explained by loading from nonlinear water tides in the gulf of california and the pacific ocean the residual nonlinear tide is 65 db less than the m2 tide the signal at 3 times the m2 frequency is compatible with a linear model or with nonlinear hysteresis loops provided that nonlinear dissipation occurs throughout the earth nonlinear dissipation in the rocks near the strainmeter would produce a larger signal than is seen

on analysis and prediction of tides on the west coast of great britain summary long period tidal records from eight ports on the west coast of great britain are analysed using both the harmonic method and the response function time series up to 9 5 yr were used so that fine structure of certain regions of high energy in the tidal residual spectrum may be examined this also assisted in accurate separation of tides from surges according to the currently accepted formulation of m1 its composition is not compatible with its actual composition in the real tide and as such has no useful purpose to serve in computation of predictions constituents sa ssa ma and mb are adversly affected by weather and long records are essential for their accurate separation it has been observed that annual perturbations of s2 similar to those confirmed in recent years for m2 also exist but these are not readily recognisable because their speeds are the same as those of constituents t2 and r2 these perturbations being highly sensitive to meteorological forces are mainly responsible for cusps or humps in the vicinity of major tidal constituents in tidal residual spectra the relationship of radiational and gravitational tides is found to be in very good agreement with theoretical results in summer months non predictable variance reduces to about half of the annual variance reflecting the regional weather conditions of summer and winter

tidal parameters for an inelastic earth abstract the gravimetric factors for an elliptical uniformly rotating earth are computed according to a new definition with respect to wahr s results and considering the mantle inelasticity the love numbers h and k are defined in the elliptical earth case to correspond to the love spherical definition they become latitude dependent the tidal parameters discussed in this paper are computed for an inelastic earth s mantle the numerical results show an increase of 0 4 of the gravimetric factors with respect to the wahr s values the love numbers h and k increase by 1 4 to 3 with respect to the elastic case

microfossils and possible microfossils from the early archean onverwacht group barberton mountain land south africa there is widespread textural evidence for microbial activity in the cherts of the early archean onverwacht group layers with fine carbonaceous laminations resembling fossil microbial mats are abundant in the cherty metasediments of the predominantly basaltic hooggenoeg and kromberg formations in rare cases filamentous microfossils are associated with the laminae the morphologies of the fossils as well as the texture of the encompassing laminae suggest an affinity to modern mat dwelling cyanobacteria or bacteria a variety of spheroidal and ellipsoidal structures present in cherts of the hooggenoeg and kromberg formations resemble modern coccoidal bacteria and bacterial structures including spores the development of spores may have enabled early microorganisms to survive the relatively harsh surficial conditions including the effects of very large meteorite impacts on the young earth

the early archaean nondweni greenstone belt southern kaapvaal craton south africa part i stratigraphy sedimentology mineralization and depositional environment abstract the nondweni greenstone belt is an exceptionally well preserved 3 4 ga succession of predominantly volcanic rocks near the southern margin of the kaapvaal craton nondweni group rocks show both similarities and differences to the barberton sequence of similar age 300 km to the north in contrast with the latter none of the nondweni lavas exceed 23 mgo and spinifex textures are exclusively of pyroxene type the characteristics of the lavas and magma genesis are discussed in part ii of this series of papers three formations are recognized in the nondweni group the lowermost mogongolozi formation comprises basaltic andesites komatiitic andesites and basalts with intercalated coarser grained pyroxenites and gabbros the toggekry formation is a felsic unit of quartz sericite schists with small cu zn massive sulphide ore bodies of volcanogenic origin the uppermost witkop formation comprises mainly basalts komatiites and komatiitic basalts intercalated with chert layers and capped by a clastic sedimentary succession the total exposed thickness of the nondweni group is 16 500 m is the result of duplication of stratigraphy and tectonic thickening during early d1 thrusting in the bedding plane of much thinner lithological units tuffaceous sediments comprise a relatively minor component of the stratigraphy but are indicative of depositional environment banded chert layers are largely derived from accumulations of accretionary lapilli tuffs although a diverse origin is indicated for some varieties at the base of the witkop formation a number of undeformed banded coarse grained graphitic quartzite bodies entirely devoid of sedimentary structures are considered to have originated as hydrothermal deposits resulting from fumarolic activity selective brecciation of layers resulted from explosive release of fluids and gases the textures of these bodies are in marked contrast to the highly rounded pseudo conglomerates from the clastic sedimentary succession at the top of the witkop formation this 500 m thick succession passes upwards through reworked tuffs and alluvial fan deposits into a zone of evaporites and stromatolites swallow tail twin crystals of barite and an evaluation of crystal interfacial angles are indicative f replacement of primary evaporative gypsum most primary features of the nondweni greenstone belt suggest a shallow water or subaerial depositional environment and together with characteristics of the magma composition indicate a tectonic setting in a subduction related continental margin setting

response of the ganges dispersal system to climate change a source to sink view since the last interstade the forcing of sediment dispersal systems by climate is widely accepted but there remains disagreement on the general responses to climate change such as how resulting signals propagate downstream and ultimately how they are preserved in the stratigraphic record towards a better understanding of these issues this paper presents a comprehensive overview of ganges dispersal system behavior since the last interstade which reveals major coeval responses to changes in the south asian monsoon at 3000 km from its mountain headwaters to deep sea fan the ganges dispersal system is immense and yet shows tight coupling between source area catchment basin and coastal and marine depocenters furthermore system wide responses and downstream transfer of the signal appear to occur at least as fast as current temporal resolution of 1 2 ky this tight linkage of source to sink components is considered a function of the southwest summer monsoon s overwhelming control on regional hydrology about 80 of the ganges discharge and 95 of its sediment load are delivered to the margin during only 4 months making the system extremely sensitive to this seasonal forcing in addition the regional scale and distribution of the monsoon weather system means that changes in atmospheric circulation affect the entire drainage basin rather than local subcomponents finally despite its present intensity strength of the summer monsoon has varied significantly over the past 150 ky under orbitally driven changes in insolation and global glacial boundary conditions the resulting changes in precipitation both well above and below modern values have forced system wide responses ranging from glacier advance retreat to sediment fluxes to the margin and deep sea fan the overall conclusions are 1 that this immense dispersal system responds to multimillennial scale 104 years climate change in a system wide and largely contemporaneous manner and 2 that major sedimentary signals can be transferred rapidly from source to sink with little apparent attenuation furthermore these acute responses to climate change have produced sedimentary stratigraphic features that diverge from traditional sequence models in their nature and timing

high resolution sequence stratigraphy of clastic shelves iii applications to reservoir geology abstract high frequency clastic shelf sequences contain porous deposits consisting of coastal to shallow water sandstones and conglomerates which may represent very good reservoirs and therefore critical targets for exploration and production as well as for fluid hydrocarbon water or co2 storage the study of these reservoirs following a sequence stratigraphic approach is essential to predict their features and distribution within systems tracts forming high frequency sequences which in turn compose higher rank systems tracts and sequences a critical aspect to improve the exploitability of the reservoirs is their heterogeneity which directly affects the volume of the reservoirs and determine internal compartmentalization the heterogeneity can be primary related to depositional processes influencing grain size and facies distribution and secondary related to diagenesis in particular the primary heterogeneity is referred to the facies variability from distal to proximal settings to the accumulation of condensed shell beds and to facies characteristics of bedsets whereas the secondary heterogeneity derives from diagenetic processes at sequence stratigraphic surfaces and facies contacts and within sandbodies both the distribution of reservoirs and their heterogeneity can be predicted following a high resolution sequence stratigraphic approach ultimately the integration of subsurface data with the analysis of outcrop analogs is essential to better understand the features of clastic shelf reservoirs and to develop 3d models of fluid migration

facies associations in warm temperate siliciclastic deposits insights from early pleistocene eastern mediterranean rhodes greece diverse abundant and usually well preserved communities of skeletal organisms occur in the lower pleistocene gelasian siliciclastic deposits of the greek island of rhodes benthic foraminifers molluscs and bryozoans have been studied in four measured and sampled sections located in the northern part of the island among these bottom dwelling organisms numerous extant taxa are good environmental indicators and combined with field observations and sedimentological data they provide information on the probable conditions in which they developed the siliciclastic deposits of the kritika formation have been divided into 14 different bio and lithofacies which have been further grouped into four facies associations corresponding to four different environmental settings 1 continental to fluviatile 2 brackish water lagoonal deltaic 3 infralittoral 0 20 m and 4 upper circalittoral depths of 20 40 m but also down to c 50 60 m among the marine facies associations several characteristic biocoenoses have been recognized soft bottoms fine to coarse sands and gravels seagrass meadows biogenic calcareous crusts on drowned beachrock slabs red algal rhodoliths and bivalve shell beds in the studied sections 13 superimposed genetic sequences have been documented the repetition of similar facies associations within each sequence suggests 1 a possibly eustasy controlled cyclic sedimentation 2 a general subsidence of rhodes during the deposition of the studied facies associations and 3 a mostly constant range of environmental conditions i e sedimentation rates and temperature throughout the gelasian

geomorphic constraints on landscape sensitivity to climate in tectonically active areas abstract the geomorphology of fluvial landscapes is known to record information about uplift rate spatial patterns of faulting and tectonic history data is far less available when addressing the sensitivity of common geomorphological metrics such as channel steepness to climatic boundary conditions we test the relationship between channel steepness and precipitation rate by measuring a large number of channels in different mountainous areas these regions exhibit a tenfold variation in precipitation rate between them 100 1000 mm y 1 but have similar uplift rates allowing the tectonic variable to be controlled by accounting for the orographic coupling of rainfall with uplifted topography we find that channel steepness is significantly suppressed by higher precipitation rates in a measurable way that conforms to simple stream power erosion laws and empirical constraints on their parameters we demonstrate this using modern and estimated glacial precipitation rates and climate emerges as an important quantifiable control on channel geometry these findings help to explain why highly variable measurements of channel steepness are reported from different locations and provide important empirical constraints on how climate shapes tectonically active landscapes

chronology of the lower middle pleistocene succession of the south western part of the crotone basin calabria southern italy biostratigraphy based on calcareous nannofossils integrated by magnetostratigraphic geochronological and isotopic data allowed establishing a precise chronological framework for the pleistocene

the relation between climate and river processes landforms and deposits during the quaternary abstract the extent to which river processes and morphology are dependent on climate is an old question when looking at large time scales climatic cyclicity seems to coincide with alternating events in fluvial development however the shorter the time scales at which fluvial development is considered the more it is difficult to find a close correspondence with climate evolution ultimately it appears that the response time of river processes to climatic change may restrict the sensitivity of the fluvial systems to adapt to short climatic oscillations the impact of climate on fluvial systems is largely transferred to these systems by the climate determined soil cohesion and peak discharges the latter factors are especially related to vegetation cover and permafrost conditions finally a number of basin characteristics are discussed that demonstrate that fluvial systems are not completely controlled by climate

an epeiric ramp low energy cool water carbonate facies in a tertiary inland sea murray basin south australia the murray supergroup records temperate water carbonate deposition within a shallow mesotrophic oligo miocene inland sea protected from high energy waves and swells of the open ocean by a granitic archipelago at its southern margin rocks are very well preserved and exposed in nearly continuous outcrop along the river murray in south australia most facies are rich in carbonate silt contain a background assemblage of gastropods especially turritellids and infaunal bivalves and are packaged on a decimetre scale defined by firmground and hardground omission surfaces bioturbation is pervasive and overprinted resulting in rare preservation of physical sedimentary structures facies are grouped into four associations large foraminiferan bryozoan echinoid bryozoan mollusc and clay facies interpreted to represent shallow water 50 m deposition under progressively higher trophic resource levels from low mesotrophy to eutrophy and restricted marine conditions from relatively offshore to nearshore regions a large scale shift from high to low mesotrophic conditions within lower miocene strata reflects a change in climate from wet to seasonally dry conditions and highlights the influence terrestrially derived nutrients had upon this shallow land locked sea overall low trophic resource levels during periods of seasonally dry climate resulted in a deepening of the euphotic zone a widespread proliferation of foraminiferan photozoan fauna and a relatively high carbonate productivity inshore heterozoan facies became progressively muddier and restricted towards the shoreline in contrast periods of wet climate led to rising trophic resource levels resulting in a shallowing of the euphotic zone a decrease in epifaunal and seagrass cover and widespread development of a mostly heterozoan biota dominated by infaunal echinoids rates of carbonate production and accumulation were relatively low the murray basin is best described as an epeiric ramp wide facies belts developed in a shallow sea on a low angled slope reaching many hundreds of kilometres in length grainy shoal and back barrier facies were absent internally generated waves impinged the sea floor in offshore regions and because of friction along a wide and shallow sea floor created a low energy expanse of waters across the proximal ramp storms were the dominating depositional process capable of disrupting the entire sea floor

limestone pseudoconglomerates in the late cambrian gushan and chaomidian formations shandong province china soft sediment deformation induced by storm wave loading this paper focuses on the formative processes of limestone pseudoconglomerates in the gushan and chaomidian formations late cambrian of the north china platform shandong province china the gushan and chaomidian formations consist mainly of limestone and shale marlstone interlayers wackestone to packstone grainstone and microbialite as well as numerous limestone conglomerates seventy three beds of limestone pseudoconglomerate in the gushan and chaomidian formations were analysed based on clast and matrix compositions internal fabric sedimentary structures and bed geometry these pseudoconglomerates are characterized by oligomictic to polymictic limestone clasts of various shapes i e flat to undulatory disc blade and sheet marlstone and or grainstone matrix and various internal fabrics i e intact thrusted edgewise and disorganized as well as transitional boundaries limestone pseudoconglomerates formed as a result of soft sediment deformation of carbonate and argillaceous interlayers at a shallow burial depth differential early cementation of carbonate and argillaceous sediments provided the requisite conditions for the formation of pseudoconglomerates initial deformation i e burial fragmentation liquefaction and injection and subsequent mobilization and disruption of fragmented clasts are two important processes for the formation of pseudoconglomerates burial fragmentation resulted from mechanical rupture of cohesive carbonate mud whereas subsequent mobilization of fragmented clasts was due to the injection of fluid materials liquefied carbonate sand and water saturated argillaceous mud under increased stress storm wave loading was the most probable deformation mechanism as an external triggering force subsequent re orientation and rounding of clasts were probably prolonged under normal compactional stress eventually disrupted clasts along with matrix materials were transformed into pseudoconglomerates by progressive lithification soft sediment deformation is prevalent in alternate layers of limestone and mud marl stone and or grainstone regardless of their depositional environments

atmospheric pressure and gravity summary gravity green s functions for a column load of a model atmosphere on a spherical elastic earth are presented and they are used to evaluate the contribution of global atmospheric pressure variations to local gravity the green s functions are found to be relatively insensitive to the details of the model atmosphere but they are dependent on the temperature at the base of the column and on the relative height difference between the base of the column and the gravity station the total signal that global pressure systems contribute to gravity is about 30 gal of which about 90 per cent is produced by the atmosphere within 50 km of the gravity station a zone between 50 and 1000km from the gravity station contributes a couple of gal as does the remainder of the globe this pattern the coherence scale of pressure fluctuations the time and spatial scales appropriate to the hydrostatic approximation and the distance of the gravity station from the oceans suggest a division of the globe into local regional and global zones data requirements processing details and the reliability of the computed signal are different in each zone the local zone is within about 50 km of the gravity station within this zone pressure changes rapidly in time but is spatially coherent so that hourly observations of pressure and temperature at the gravity site alone are sufficient to compute an accurate correction except when a front is passing through the regional zone extends from the edge of the local zone to between several hundred and a thousand kilometres the signal from this zone is small and is only weakly coherent with the signal from the central zone so that a rather sparse array of hourly samples of pressure and temperature are required the gravity signal from the global zone can reach about a gal it varies on a time scale of days and is influenced by the response of the oceans to pressure variations previously reported observations that the admittance between local pressure and gravity residuals depends on epoch frequency or site are most probably due to incorrect modelling a proper local regional temperature and global correction can adequately account for the gravity signal from the atmosphere to within a few tens of ngal in the diurnal band and about 100 ngal in the days to seasonal band except during extreme weather conditions the application of the local correction lowers the power spectral density of the gravity residuals in every band from seasonal to hourly the regional global and temperature corrections lower the residual noise in the seasonal and synoptic bands but are not consistently effective at periods less than about half a day

geophysical analysis of zonal tidal signals in length of day summary the earth s zonal response coefficient k is estimated from the tidal signals in the observed length of day lod data its magnitude and phase are functionals of the earth s internal structure and dynamics in this paper an analysis of 13 years of precise lod data 1980 1992 reveals strong signals for nine zonal tidal groups ranging from 5 to 35 days in period numerical estimates of k for 27 major tides are thus obtained 11 among which are considered sufficiently high in signal to noise ratio to provide meaningful geophysical constraints on the earth s rotational dynamics the results favour a k magnitude close to but somewhat smaller than 0 315 which is the theoretical value for an elastic mantle completely decoupled from the fluid core plus equilibrium oceans a small amount of dispersion is also detectable where shorter periods tend to have lower k magnitude and larger phase lag our k magnitude estimates are consistent with two recently published non equilibrium ocean tide models and an anelastic response in the mantle although an equilibrium response in the ocean and a purely elastic response in the mantle is not disallowed phase lags of a few degrees are required by both ocean tide models and by our data

observations of the velocity response to wind forcing in the upper ocean the response of the horizontal velocity field to forcing by the local wind was observed in the upper 150 m of the ocean by profiling with vector measuring current meters from the research platform flip as it drifted off the coast of california in january 1977 in the mixed layer approximately 50 m deep motion at frequencies lower than 0 1 cph was coherent with the wind stress rotary cross spectral analysis showed that the shear in the surface layer was related to the local wind stress and that the structure of the response at low frequencies was similar to but did not agree completely with the predictions of simple linear eddy viscosity models

geomorphic tectonic control of sediment discharge to the ocean the importance of small mountainous rivers analysis of data from 280 rivers discharging to the ocean indicates that sediment loads yields are a log linear function of basin area and maximum elevation of the river basin other factors controlling sediment discharge e g climate runoff appear to have secondary importance a notable exception is the influence of human activity climate and geology on the rivers draining southern asia and oceania sediment fluxes from small mountainous rivers many of which discharge directly onto active margins e g western south and north america and most high standing oceanic islands have been greatly underestimated in previous global sediment budgets perhaps by as much as a factor of three in contrast sediment fluxes to the ocean from large rivers nearly all of which discharge onto passive margins or marginal seas have been overestimated as some of the sediment load is subaerially sequestered in subsiding deltas before the proliferation of dam construction in the latter half of this century rivers

extension of the astronomically calibrated polarity time scale to the miocene pliocene boundary the early pleistocene to late pliocene astronomically calibrated time scale of shackleton et al 1 and hilgen 2 is extended to the miocene pliocene boundary this is done by correlating the detailed record of caco3 cycles in the trubi and the lower part of the overlying narbone formation rossello composite section sicily to the astronomical record using 1 inferred phase relations between these caco3 cycles and the corresponding orbital cycles of precession and eccentricity and 2 calibration points provided by the previously established astronomical calibration of sapropelitic layers which occur in the topmost part of the caco3 record 2 this correlation allows all small scale caco3 cycles in the rossello composite section to be coded after the correlative precession peak and to be dated astronomically with an accuracy of 1 ky in combination with the available high resolution magnetostratigraphy it further allows the construction of an astronomically calibrated geomagnetic polarity time scale for the major part of the gilbert and gauss chrons this new time scale gives ages for the reversal boundaries of the kaena 3 04 3 11 ma and mammoth 3 22 3 33 ma the gilbert gauss chron boundary 3 58 ma and the reversal boundaries of the cochiti 4 18 4 29 ma nunivak 4 48 4 62 ma sidufjall 4 80 4 89 ma and thvera 4 98 5 23 ma these ages are significantly older than the ages given by conventional time scales age discrepancies gradually increase with increasing age the age of 5 32 ma for the miocene pliocene boundary as defined by the base of the trubi on sicily is almost 0 5 m y 9 5 older than the presently accepted age of 4 86 ma 3 these considerable discrepancies with the conventional time scale can either be explained by an consistent error in the decay constants used in k ar radiometric dating or more likely by diffusional loss of radiogenic argon

pliocene pleistocene sedimentary and geomorphologic development of the vasilikos river catchment s cyprus in relation to uplift of the troodos ophiolite and climate related changes the pleistocene development of the vasilikos river exemplifies the interaction of focused tectonically induced surface uplift and climate influenced changes the resulting sediments are well exposed in vasilikos quarry and in the main river catchment further east an important erosional surface incises the highest level oldest fluvial conglomerates down into late pliocene early pleistocene open marine mudrocks nicosia formation allowing integration with the circum cyprus sedimentary geomorphic development f1 f4 stages to determine where the quarry deposits lie in relation to the vasilikos river catchment the fluvial deposits were mapped and valley profiles were constructed revealing four main episodes each associated with incision and distinctive fluvial deposition source lithology strongly influenced channel morphology infill and adjacent slope sediment colluvium composition palaeosols particularly red brown terra rossa developed on abandoned fluvial terraces and adjacent hillslopes especially overlying f3 surfaces the combined evidence allows close correlation of the vasilikos river and quarry deposits relatively coarse chalky conglomerate breccia and fine grained colluvium calcareous silt cyprus harvara developed especially on lower hillslopes following incision mainly above f2 and f3 surfaces based on regional comparisons overall sediment aggregation ended during the early pleistocene the f1 f2 surfaces and deposits are inferred to be middle pleistocene the f3 ones later middle pleistocene and the f4 ones near the middle late pleistocene boundary geomorphology and deposition were tectonically forced during strong focused early middle pleistocene surface uplift coarse clastic ruff off and palaeosol development terra rossa and related sediment aggradation are inferred to have increased during warm humid periods late pleistocene geomorphology and deposition were more influenced by climatic change with semi perennial streamflow rapid sediment aggradation and palaeosol terra rossa development during warm humid periods interglacials cooler glacial periods enhanced fluvial incision sediment bypassing and hillslope colluvial processes e g frost shattering downslope creep and mass flow when sediment transport bypassing exceeded sediment supply neotectonic faulting affected the catchment but did not greatly affect geomorphology or sediment supply although climate climate change and eustatic sea level change had an important influence tectonics is interpreted as the fundamental driver of geomorphological development and fluvial sedimentation with implications for other areas regionally to globally

the lower to middle pleistocene valle di manche section calabria southern italy state of the art and current advances the valle di manche vdm section represents one of the best documented on land marine records of the early to middle e m pleistocene transition available to date accordingly the vdm succession is among the few appropriate candidates to host the gssp of the middle pleistocene ionian stage in particular the vdm section uniquely documents the matuyama brunhes magnetic reversal mid mis 19 which is agreed to be the main criterion for defining the chronostratigraphic position of the base of the middle pleistocene the section also yields a wide range of chronological paleoclimatic and stratigraphic data sets that allow long distance correlation with both marine and terrestrial reference records notably the stratigraphy across the mis 19 interglacial is greatly expanded permitting a precise and detailed investigation of this critical interval the section is also easy to reach and fortunately the exposure is destined to persist therefore the section fulfills the essential requirements to host the gssp for the ionian stage and middle pleistocene subseries we suggest that the gssp be placed at the base of the pitagora ash a prominent bed that occurs in mid mis 19 close to the matuyama brunhes magnetic reversal here we present and discuss scientific information gathered in the past two decades and give a preliminary account of the work to which we are presently committed that aims at improving our knowledge on the vdm section

funnel shaped breccia filled clastic dykes in the late cambrian chaomidian formation shandong province china abstract some examples of a funnel shaped structure filled with both angular and rounded clasts occur in a peloidal grainstone bed of the chaomidian formation late cambrian in the jiulongshan area shandong province china the clasts consist of peloidal grainstone which is the same as that of the walls of the funnels the structures are interpreted as dykes formed by upward escape of pore water and or fluidized sediment through a narrow conduit which was gradually widened by the force of the intruding fluid sediment the erosional capacity of the pressurized fluid sediment mixture consequently diminished upwards which explains the gradual decrease in intensity of fragmentation from the adjoining walls in this direction

sedimentary evolution of the neogene quaternary crotone basin southern italy and relationships with large scale tectonics a sequence stratigraphic approach abstract the crotone basin is a neogene quaternary depocenter developed along the ionian margin of calabria southern italy the basin opening was concomitant with the onset of spreading of the tyrrhenian backarc basin during late serravallian and the subduction of the ionian lithosphere below the calabrian arc the adoption of modern sequence stratigraphic principles to subdivide the basin fill into stratigraphic sequences of different rank bounded by subaerial unconformities has allowed cycles of creation and loss of accommodation mainly related to tectonics to be recognized in particular an alternation between phases of basin subsidence concomitant with spreading of the tyrrhenian backarc basin and forward migration of the arc and phases of compressional or transpressional tectonics accompanied by basin uplift and stopping of arc migration are well recognizable in the basin fill in particular for the late messinian to late pleistocene part of the succession the present study highlights the effectiveness of the sequence stratigraphic method in basin analysis to decipher the effects of large scale tectonic events on sedimentation and ultimately to reconstruct the geodynamic evolution of the central mediterranean

the impact of milankovitch scale climatic forcing on sediment supply abstract stratigraphy is the main technique to predict the occurrence of potential reservoirs and seals in the oil industry stratigraphic tools used are stratigraphic observations from drilled wells rock samples and wireline logs and seismic interpretation nowadays computer modelling allows scenario forecasting of the sequence to be expected application of these tools indicates that the key input parameters are initial basin topography subsidence eustasy and sediment supply the first three parameters are usually well constrained or can readily be deduced from well and seismic data however the fourth sediment supply is loosely defined and because of that it is used to calibrate the model in the present article the controls on sediment supply are reviewed and the impact of in particular milankovitch scale climatic forcing on sediment supply is tested on the neogene of the niger drainage and delta system sediment supply is controlled by a complex interplay of geographic and climatic factors such as 1 relief or mountain height 2 the size and temporal storage capacity of the drainage area 3 overall climate 4 amount and seasonality of precipitation and 5 vegetation cover studies in geomorphology have indicated that although complex computer models can be made to predict erosional product for the present a large scale sediment supply prediction should be based on the combination of palaeogeographical palaeoclimatological and erosion potential maps more detailed sediment supply predictions should include milankovitch scale variations the climatic impact of these variations is mainly felt when we are in a transition between two climates then the area will experience regular climatic changes from e g wet rainforest to dry monsoonal climate or low to high sediment supply respectively this concept was tested in the forward modelling package stratagem on the neogene of the niger delta four scenarios were evaluated using various combinations of large and milankovitch scale sediment supply curves combined with global or milankovitch scale eustatic sea level curves the results confirm the impact of both large scale and milankovitch scale climatic forcing on sediment supply however in an icehouse world the various scenarios also suggest that the effect of eustatic sea level fluctuations overshadows the impact of milankovitch scale sediment supply by contrast in a greenhouse world the impact of milankovitch scale sediment supply is expected to be more significant in the absence of significant sea level fluctuations

non linear tides observed with the superconducting gravimeter summary a four year record from the superconducting gravimeter at cantley quebec is examined for non linear tidal effects a linear response is first determined from an adaptation of the response method used in the tidal analysis of sea level residuals left by the linear response clearly show anomalies of a few tens of ngals 1 ngal 10 l ms these residuals are most evident in the semi diurnal band but the diurnal ter diurnal and quart diurnal bands are also affected a subsequent analysis shows that these are most likely the loading effects of shallow water non linear tides principally in the bay of fundy and the east coast of north america the loading effect of global degree three diurnal and semi diurnal tides is also interpreted the amplitude of the latter tides in the open ocean is a few millimetres so the superconducting gravimeter is sensing ocean tides at a level surpassing that of most standard tide gauges and of satellite altimetry the linear response analysis and the identification and removal of the non linear tides provides the clearest look to date at the tide free spectrum it is shown that any simple non linear response that doubles the frequency must be at least 65 db below the linear response if the source of the non linearity is in the solid earth and 82 db below the linear response if the source of the non linearity is in the instrument if the observed non linear response is entirely due to loading by non linear ocean tides as seems likely then these figures are 76 db and 93 db respectively

climatic modulation of timing of systems tract development with respect to sea level changes middle pleistocene of crotone calabria southern italy abstract climate change has traditionally played a secondary role in the literature behind eustasy and tectonics with eustasy regarded as the main controlling factor in development of sedimentary sequences here we emphasize the role of the interaction of climate modulated sediment supply and sea level change particularly its potential impact on sequence development we discuss a case history from the lower middle pleistocene of the highly subsiding valle di manche shelf area crotone basin calabria southern italy where a stack of cyclothems spanning from late marine isotope stage mis 22 to full mis 18 preserves a full record of eustatic cycles glacials included tectonics certainly played a critical role in the creation of local accommodation ultimately controlling the preservation of an almost complete sedimentary record however its role as a factor controlling the sediment flux on milankovian scale can be ruled out direct comparisons between data concerning 18o pollen and physical stratigraphy demonstrate that climate induced changes in sediment load caused significant deviations from the predicted timing and magnitude of the responses to sea level changes in the traditional sequence model a phase lag occurred in the timing of systems tracts leading to a significant delay of one quarter of a sea level cycle specifically climate driven sediment discharge during sea level rise triggered progradation of shelf margin wedges which should thus be considered lowstand in their architecture and transgressive in their timing this was generated by a shift toward drier conditions leading to extensive deforestation and consequent lowering of the threshold for slope erosion and mass wasting processes in the source area due to the reduced extent of the transfer zone sedimentary signals were conveyed rapidly from source to sink with little apparent attenuation suggesting that the milankovitch scale climate changes can lead to rapid source to sink responses on tectonically active margins fed by high gradient short headed streams the studied case history demonstrates that the impact of milankovitch scale climatic forcing on sediment supply in an icehouse world can be more supluential than sediment redistribution due to corresponding sea level fluctuations these findings emphasize that a reconstruction of the timing of systems tract development with respect to sea level changes based on a sequence stratigraphic approach may be misleading whenever independent chronological and climatic constraints are not available

a synthetic pollen record of the eastern mediterranean sapropels of the last 1 ma implications for the time scale and formation of sapropels abstract the quaternary climate of southern europe south italy and greece is investigated by pollen analysis of the sapropels which were deposited in the deep eastern mediterranean sea during the last 1 million year ma the time scale of core kc01b in the ionian sea has been established by tuning its oxygen isotopic record to the ice volume model of imbrie and imbrie 1980 for the last 250 000 year 250 ka the previous pollen studies and astronomical tuning have been confirmed sapropels were deposited under a large range of mediterranean climates fully interglacial fully glacial and intermediary as revealed mainly by the balance between the respective pollen abundances of oak quercus and sage brush artemisia the high value of the oak reveals the warm and wet climate of an interglacial and the high value of the sage brush the dry and cold climate of a glacial whereas the mediterranean climate is directly related to the variation of the high latitude ice sheets the deposition of sapropels is not so in contrast with the wide climatic range sapropels were deposited only when summer insolation in the low latitudes reached its highest peaks however between 250 ka and 1 ma that stable pattern is not yet established only six sapropels are observed many expected ones do not appear even as ghosts signalled by peaks of barium abundance that remain after the post deposition oxidation of organic matter the pattern of sapropel formation in stable and direct relationship to highest insolation does not seem to apply for five of those sapropels neither climate extremes are observed they mainly formed during intermediary types of mediterranean climate in contrast one sapropel and one ghost relates to a relatively low peak of insolation and its climate is of a unique composite type not seen later this might suggest an unsuspected more complex pattern linking the formation of mediterranean sapropels to the astronomical configuration

evolution of fluids and metamorphic ore remobilization in the felbertal scheelite deposit eastern alps abstract the felbertal scheelite deposit displays a variety of host rocks and ore types macroscopic and microscopic evidence indicates the formation of the ore mineralization in a geothermal system including explosion and subaqueous surface phenomena at an active continental margin in upper proterozoic upper riphaean lower vendian time the alpine metamorphism and tectonism caused a pervasive metamorphic hydrothermal ore redeposition and a spatial redistribution from smaller volumes to larger volumes of low grade ores especially in the western field microthermometrical studies on quartz scheelite beryl calcite and fluorite in the metamorphosed felbertal scheelite deposit show two types of fluid inclusions aqueous fluid inclusions with variable amounts of co 2 up to 20 wt as well as aqueous fluid inclusions without a measurable co 2 content both types are of alpine origin and were trapped during the alpine retrograde metamorphism therefore the microthermometrical data do not record the conditions of the original pre alpine tungsten formation however it was possible to construct a path for the fluid evolution and the cogenetic ore redeposition during the alpine retrograde metamorphism from the microthermometrical and petrographical data

african monsoons an immediate climate response to orbital insolation the croll milankovitch astronomical theory of climate1 3 has received strong support from the evidence of a linear climatic forcing by obliquity and precession although nonlinearity had to be assumed for eccentricity4 5 moreover interglacials have appeared to be controlled by the orbital insolation6 although a phase shift of 6 000 5 000 yr is seen between an astronomical climate index and terrestrial climate indicators dominated by the northern ice sheet dynamics climate proxy data of low latitudes are less directly dependent on the ice sheets here it is shown that during the past 464 000 yr african monsoons signalled by the east mediterranean sapropels were heaviest always and only when a northern summer monsoon index computed from the orbital variation of insolation reached maximum values this occurred during all the interglacials but also twice during glacial periods thus tropical aridity is not the single climatic pattern of glacial periods an immediate terrestrial climate response to orbital variations of insolation is established

calibration of the c 14 timescale over the past 30 000 years using mass spectrometric u th ages from barbados corals uranium thorium ages obtained by mass spectrometry from corals raised off the island of barbados confirm the high precision of this technique over at least the past 30 000 years comparison of the u th ages with 14c ages obtained on the holocene samples shows that the u th ages are accurate because they accord with the dendrochronological calibration before 9 000 yr bp the 14c ages are systematically younger than the u th ages with a maximum difference of 3 500 yr at 20 000 yrbp the u th technique thus provides a way of calibrating the radiocarbon timescale beyond the range of dendrochronological calibration

how plausible are high frequency sediment supply driven cycles in the stratigraphic record abstract this paper is an attempt to quantify the plausible time scales of clastic sediment supply variations at the entrance of sedimentary basins our approach is based on the sedimentary system concept which simplifies natural systems by dividing them into three zones of dominant processes the erosion the transfer and the sedimentation subsystems we examine recent results from geomorphology which show that frequent climate changes can induce high frequency sediment flux variations at the outlet of the source area we put forward the crucial role of the transfer subsystem which conveys sediment from the erosion zone to the basin by applying a diffusive model to a number of worldwide rivers we extend from large 1000 km to intermediate 300 km rivers the previous finding that the transfer subsystem acts as a buffer for short periods sediment pulses tens to hundreds of kiloyears this implies that high frequency stratigraphic cycles in clastic accumulations fed by large drainage systems are unlikely to reflect sediment supply cycles of tens to hundreds of thousands of years of periodicities

stratigraphic paleoecology of the valle di manche section crotone basin italy a candidate gssp of the middle pleistocene abstract macro benthic assemblages from the lower to middle pleistocene of the valle di manche vdm section crotone basin southern italy were used to assess the value of merging paleoecological quantitative patterns into a sequence stratigraphic framework two way cluster and detrended correspondence dca analyses were applied to the macrofossil data matrix comprising 22 samples 157 species and 5761 specimens specifically two way cluster analysis allowed for the characterization of five shelf related biofacies and four sub biofacies along section biofacies change along the vdm generally supported previous sequence stratigraphic interpretations and suggests that faunal turnover is the result of habitat tracking dca stratigraphic curves dc1 sample scores calibrated to the depth preferences of extant species provided quantitative estimates of bathymetry and the assessment of related parameters e g grain size sedimentation turbidity when plotted stratigraphically calibrated dc1 scores highlight the magnitude of relative sea level fluctuations at the scale of the section as well as individual sequences and systems tracts additionally dca derived paleobathymetric trends track the oscillations of the 18 o record indicative of global sea level change based on this comparison it is held that macro benthic assemblages once supported by a robust statistical interpretation can be employed successfully as a proxy for 18 o depicting the variability in local water depths the potential of this approach is especially high for studies in shallow water depositional settings where dependable 18 o data are typically difficult to obtain

early archean foredeep sedimentation related to crustal shortening a reinterpretation of the barberton sequence southern africa abstract the upper dominantly terrigenous sedimentary successions of the early archean barberton sequence kaapvaal province record an evolution similar to that of phanerozoic foredeeps and may represent the oldest known foredeep sequence rather than a passive continental margin sequence as previously proposed pre foredeep ocean crust the 3 5 ga old onverwacht group consists of bimodal volcanics with intercalated shallow water sediments gravity modeling and boundary shear zones indicate that deformed onverwacht crust was obducted northward onto sialic continental crust immediately before during or after burial by the synorogenic terrigenous clastic fill foredeep basin deepening due to crustal loading from the south is recorded by basinal iron formation chert and mudstone of the basal fig tree group which accumulated paraconformably on the onverwacht overlying sediments of the fig tree group consist of 2 km of submarine fan greywackes and mudstones shoaling of the basin is indicated by the transition to the overlying braided alluvial and shallow marine sediments of the ca 3 3 ga old moodies group 3 km thick changing ree patterns and relative abundances of ni cr sr th and ur in the sediments of the fig tree and moodies groups indicate a significant ultramafic mafic volcanic component diluted upward in the stratigraphic sequence by an increasing granitic contribution a similar trend is reflected in sandstone petrography in which the ratio of extrusive to intrusive rock fragments decreases upwards in the fig tree group whereas the moodies group sediments are enriched in quartz and potassium feldspar a persistent chert component in both units suggests that the tectonic setting of the basin is analogous to that of phanerozoic recycled orogens the distribution of facies in the fig tree and moodies groups and paleocurrent petrographic and geochemical data indicate progressive unroofing of a southerly source terrane consisting of the onverwacht volcanics and intercalated sediments and the 3 5 3 2 ga old ancient gneiss complex agc in addition older components of the fig tree group were recycled into overlying stratigraphie units the agc consists of mantle derived 3 5 ga old bimodal metavolcanics and metasediments a tonalite gneiss batholith metabasite dikes and meta anorthosites its structures record progressive northwestward uplift beginning around 3 4 ga ago intense homogeneous ductile strains were overprinted by northwest verging major folds rotated by large scale northwestward simple shear followed by imbricate faulting and pseudotachylite formation by 3 3 ga ago the fig tree and moodies groups had also shortened with similar kinematics to those of the agc by partly syndepositional folding and volume loss during the formation of transecting cleavage further folding and slide formation followed during subsolidus diapiric rise of the initially tabular kaap valley tonalite by 3 2 ga and emplacement of trondhjemite plutons from 3 3 to 3 0 ga ago

growth fault control of early archaean cherts barite mounds and chert barite veins north pole dome eastern pilbara western australia1pii of original article s0301 9268 97 00062 4 1

climatic patterns revealed by pollen and oxygen isotope records across the matuyama brunhes boundary in the central mediterranean southern italy a c 50 m thick section located in the crotone basin southern italy was investigated using oxygen isotopes pollen and planktonic foraminifera the section records two complete trans gressive regressive cycles mainly driven by glacio eustasy biostratigraphy and oxygen isotope chronology indicate that the section spans from marine isotope stage mis 22 c 0 87 ma to mis 18 3 c 0 73 ma thus straddling the matuyama brunhes m b boundary which occurs in the middle of mis 19 the rich pollen assemblages provide a unique record of the vegetation in the central mediterranean during the early middle pleistocene climatic transition interglacials are characterized by a mesothermic vegetation similar to the present day whereas a rain demanding conifer forest dominates the glacials of mis 20 and mis 18 this is unexpected because it is gener ally considered that during the pleistocene glacials in central mediterranean were characterized by steppe arid conditions by contrast arid conditions occur during the deglaciations these results are inconsistent with the widespread practice of linking glacials with arid conditions in the central mediterranean during pliocene and early pleistocene times this study emphasizes the need to establish more accurate land sea correlation

tidal gravity and ocean tide loading in europe b the results are presented from tidal gravity measurements at five sites in europe using lacoste and romberg et gravimeters improvements that we have made to the accuracies of these gravimeters are discussed it is shown that the standard calibration of the international center for earth tides used for worldwide tidal gravity profiles is 1 2 per cent too high the m2 and o1 observations are compared with model calculations of the earth s body tide and ocean tide loading and it is shown that there is a very significant improvement in the agreement between observations and models compared to that obtained with previous tidal gravity measurements for o1 where the ocean tide loading and attraction in central europe is only 0 4 per cent of the body tide our measurements verify that the dehant wahr anelastic body tide model gravimetric factor is accurate to 0 2 per cent it is also shown that the effects of lateral heterogeneities in earth structure on tidal gravity are too small to explain the large anomalies in previously published tidal gravity amplitudes the observations clearly show the importance of conserving tidal mass in the schwiderski ocean tide model for sites in central europe the m2 and o1 observations and the models are in agreement at the 0 1 gal 10 9 m s 2 level and tidal corrections to this accuracy can now be made to absolute gravity measurements

high resolution sequence stratigraphy of middle eocene hazad member jambusar broach block cambay basin india abstract the middle eocene hazad member of the ankleswar formation in the cambay basin is characterized by 13 sandstone units gs 0 to gs 12 representing progradational pulses within an overall fining up 2nd order transgressive systems tract tst the overall facies architecture of the hazad member implies deposition in a tide affected marginal marine deltaic environment high resolution sequence stratigraphic analysis based on core and electrolog data allows to subdivide the 2nd order tst into three 3rd order systems tracts namely i basal shaly transgressive systems tract tst followed by ii a highstand systems tract hst incorporating four intervening parasequence sets gs 0 to gs 2 gs 3 gs 4 to gs 6 and gs 7 to gs 9 separated by 4th order flooding surfaces and iii a transgressive systems tract tst at the top consisting of parasequence sets gs 10 to gs 12 capped by the kanwa shale that includes the maximum flooding surface mfs the amalgamated sands of the 3rd order sequences found landward split basinward to form six coarsening up 4th order cycles parasequence sets which are further subdivided into twenty one 5th order cycles parasequences separated by minor events of marine flooding the depositional model and paleogeographic maps using 3rd 4th and 5th order cycles reveal a minimal sand supply at the beginning of 3rd order hst and a significant increase in fluvial sand supply thereafter which resulted in progradation leading to constructive delta building till gs 9 the topmost transgressive parasequence sets constituting gs 10 to gs 12 mark landward retreat due to a paucity of sand supply and or a rise in relative sea level which resulted in back stepping of the paleoshoreline and development of estuaries over the older deltaic system the model helps to explain the extent of short term transgressive regressive cycles improving elucidation of the hydrocarbon bearing sand units of the cambay basin in future exploration

metamorphosed hydrothermal eruption breccia conglomerate in the felbertal scheelite deposit eastern alps austria abstract a metamorphosed hydrothermal eruption breccia conglomerate has been found in recently opened galleries in the western field of the felbertal scheelite deposit it belongs to the k2 ore body and covers a stratiform quartz mass and surrounding host rocks the quartz mass shows features very similar to siliceous sinters in recent explosion craters e g waiotapu new zealand the breccia displays a variable thickness commonly up to 60 cm it is continuous for at least 100 m along strike and is composed of rock fragments from the surrouding and underlying host rocks including basaltic felsic and quartz rocks these fragments reveal a variable degree of rounding due to subaqueous reworking and an elongation due to tectonism and metamorphism with increasing distance from the quartz mass the quantity of rock fragments in the breccia diminishes rapidly laterally the metamorphosed breccia conglomerate horizon interfingers with biotite amphibolites this breccia indicates 1 at least one hydrothermal eruption 2 the existence of a subaqueous erosional surface 3 the ejection of underlying and surrounding host rocks of the scheelite bearing series 4 the pre existence of the quartz mass and a bimodal rock assemblage including basaltic and felsic volcanites with an earlier tungsten mineralization mainly in quartz fragments and 5 a tungsten mineralization coeval with the formation of the matrix this matrix shows enrichments in w sn mo li be au bi as f p ba th and u

fluvial responses to climate and sea level change a review and look forward summary fluvial landforms and deposits provide one of the most readily studied quaternary continental records and alluvial strata represent an important component in most ancient continental interior and continental margin successions moreover studies of the long term dynamics of fluvial systems and their responses to external or allogenic controls can play important roles in research concerning both global change and sequence stratigraphy as well as in studies of the dynamic interactions between tectonic activity and surface processes these themes were energized in the final decades of the twentieth century and may become increasingly important in the first decades of this millennium this review paper provides a historical perspective on the development of ideas in the fields of geomorphology quaternary geology vs sedimentary geology and then summarizes key processes that operate to produce alluvial stratigraphic records over time scales of 103 106 years of particular interest are changes in discharge regimes sediment supply and sediment storage en route from source terrains to sedimentary basins as well as changes in sea level and the concept of accommodation late quaternary stratigraphic records from the loire france mississippi usa colorado texas usa and rhine meuse the netherlands rivers are used to illustrate the influences of climate change on continental interior rivers as well as the influence of interacting climate and sea level change on continental margin systems the paper concludes with a look forward to a bright future for studies of fluvial response to climate and sea level change at present empirical field based research on fluvial response to climate and sea level change lags behind a the global change community s understanding of the magnitude and frequency of climate and sea level change b the sequence stratigraphic community s desire to interpret climate and especially sea level change as forcing mechanisms and c the modelling community s ability to generate numerical and physical models of surface processes and their stratigraphic results a major challenge for the future is to catch up which will require the development of more detailed and sophisticated quaternary stratigraphic sedimentological and geochronological frameworks in a variety of continental interior and continental margin settings there is a particular need for studies that seek to document fluvial responses to allogenic forcing over both shorter 102 103 years and longer 104 106 years time scales than has commonly been the case to date as well as in larger river systems from source to sink studies of quaternary systems in depositional basin settings are especially critical because they can provide realistic analogues for interpretation of the pre quaternary rock record

normal modes of the world ocean part iv synthesis of diurnal and semidiurnal tides abstract diurnal and semidiurnal tides of second and third degree are synthesized from 60 normal modes with period in the range 8 to 96 h diurnal tides especially those of second degree can be represented by remarkably few modes the principal lunar diurnal constituent for example consists almost entirely of a single forced mode excited mainly in the pacific and indian oceans semidiurnals are spectrally more heterogeneous and more resonant than diurnals but some specific features can be attributed to individual modes several of the most energetic modes in the principal lunar semidiurnal constituent are prominent in the atlantic ocean together with the fact that diurnally excited modes are relatively weak in that region this presumably accounts for the observed tendency for the total tide to be predominantly semidiurnal in the atlantic but mixed diurnal and semidiurnal in many parts of the pacific and indian oceans

the valle di manche section calabria southern italy a high resolution record of the early middle pleistocene transition mis 21 mis 19 in the central mediterranean abstract the on land marine valle di manche section crotone basin calabria southern italy one of the candidates to host the gssp of the middle pleistocene ionian stage preserves a manifold record of independent chronological paleoclimatic and stratigraphic proxies that permit a straightforward correlation with marine and terrestrial reference records at the global scale in particular the section holds an excellent record of the matuyama brunhes magnetic reversal which occurs in the midst of marine isotope stage mis 19 we report on a complete revision of the section that improves dramatically the available dataset especially in the stratigraphic interval straddling the lower middle pleistocene boundary our benthic 18o record provides evidence that the matuyama brunhes transition the stratigraphic position of which is marked by a prominent tephra the pitagora ash occurred during full mis 19 in agreement with many records worldwide we obtained an age of 786 9 5 ka for the matuyama brunhes magnetic reversal and pinpointed the paleomagnetic transition of to a 3 cm thick interval indicating that the event was very fast since the section fulfills all the requirements to host the gssp of the ionian stage we propose that the boundary should be placed at the base of the pitagora ash ca 12 5 cm below the midpoint of the matuyama brunhes reversal

the tides of the atlantic ocean 60 degrees n to 30 degrees s this paper is a sequel to cartwright edden spencer vassie 1980 henceforth c e s v which concentrated on the tides of a small portion of the north atlantic between the midatlantic ridge and the west european shelf in both works we have aimed to discover what can be learnt of the spatial dynamic properties of the ocean tides from direct measurements in the open sea with a minimum of prejudice from the artefacts of computer models an essential background has been a development over roughly 15 years 1970 1985 of the instrumental technique of recording pressure variations on the ocean floor for long periods together with their associated acoustic recall systems and calibrating devices this instrumental development has been led principally by one of the authors r s with the help of colleagues at the bidston and wormley laboratories of the institute of oceanographic sciences ios the sea going activity described in c e s v had seemed adventurous because tidal variations offshore had not been measured before in that part of the atlantic ocean but when compared with computer generated tidal maps of the world ocean the distances reached appear small on the scale of the principal wavelengths similar measurements in the atlantic by other authorities were concentrated in a narrow band within a few hundred kilometres of the east coasts of canada and the u s a cartwright et al 1979 with the sanction of the ios we decided to bridge the gap between east and west atlantic by a few supplementary lines of pressure recordings between the existing sets some pressure records from the equatorial zone taken later as part of a climate research programme cartwright al 1987 extended the network further to the south we shall be concerned here with the analysis of these new data sets and with the interpretation of the whole available set of tidal constants from the atlantic ocean including islands and coasts

the response method applied to the analysis of superconducting gravimeter data abstract the response method a technique used in ocean tide analysis to separate linear and nonlinear components is applied to the analysis of superconducting gravimeter data a response analysis is shown to be capable of resolving small non tidal signals of a few nanogal amplitude arbitrarily close in frequency to large amplitude tidal signals a synthetic example in which a small signal is injected into a spectrally rich tidal signal is used to demonstrate how the method is applied and its advantages compared to a conventional analysis the technique is also applied to the analysis of degree 3 diurnal and semi diurnal tides in short records the degree 3 waves are easily separated and a reasonable ocean loading effect for these waves is recovered despite the fact the open ocean tide is only a few mm in amplitude finally a response analysis is used to separate gravitational tides from the radiation tides at coincident frequencies in both the diurnal and semi diurnal bands

dynamics of benthic marine communities across the early middle pleistocene boundary in the mediterranean region valle di manche southern italy biotic and stratigraphic implications abstract the valle di manche vdm section calabria southern italy offers the opportunity to investigate the ostracod turnover along a continuous shelf succession straddling the early middle pleistocene boundary and compare it against other paleoenvironmental i e mollusks and paleoclimatic uvigerina peregrina 18o records high resolution ca 1 sample m ostracod fauna quantitative data coupled with gradient analysis detrended correspondence analysis and non metric multi dimensional scaling document a strong relationship between changes in faunal composition and lithofacies vertical stacking patterns the comparison between the mollusk and ostracod derived ordination data demonstrates that the meio and macro faunal turnover is guided by a common complex gradient bathymetry the integrated ostracod mollusk gradient analysis also provides a trend in water depths along the section highlighting to what extent such multivariate approach can improve the paleoenvironmental and sequence stratigraphic interpretation of ancient shallow marine successions when plotted stratigraphically ordination major axis sample scores reveal two increasing decreasing patterns in water depth that fit well with the t r cycles previously identified paleobathymetric estimates combined with the vertical distribution of key ostracod groups i e epiphytic taxa on sandy substrates vs deep sea mud related taxa allow refining depositional trends stratal stacking patterns and position of previously not well resolved sequence stratigraphic surfaces within each t r cycle e g transgressive surface ts indeed two rapid increases in water depth values mark the tss that separate shallowing upward progradational rst from deepening upward retrogradational tst stratal stacking patterns of shelf deposits the tss which underline fine grained successions dominated by deep sea mud lover taxa are invariably constrained to the inception of interglacials marine isotope stages mis 21 and 19 identified within the vdm section by benthic foraminifera 18o values within both the vdm t r cycles the deepest conditions ca 140 m of water depth are invariably identified within the neopycnodonte unit slightly above the lightest 18o intervals the overlying decreasing bathymetric trend coupled with shifts in ostracod ecological groups allows to identify in the bryozoans lithofacies the stillstand falling of the relative sea level also tracked by a progressively heavier 18o record more stable paleobathymetric conditions around 40 45 m of water depth characterize the overlying silt sand deposits dominated by epiphytic species and showing the heaviest 18o values

a mediterranean perspective on 10be sedimentation and climate around the matuyama brunhes boundary les liaisons dangereuses abstract the 10be 9be ratio is commonly employed as a tool for establishing the stratigraphic position of paleomagnetic excursions and reversals whenever the traditional paleomagnetic approach fails to provide conclusive results in particular it is held that 10be production rates in the atmosphere depend on the strength of the earth s magnetic field and the fallout and deposition of cosmogenic beryllium at the surface happen on a very short time scale however investigations performed on terrestrial and marine successions demonstrate that the 10be record and the paleomagnetic signal are often asynchronous mechanisms that control the conveyance and deposition of cosmogenic 10be to the seafloor are still ambiguous and poorly documented here we discuss the dynamics of 10be in a central mediterranean marginal marine depositional scenario characterized by a pervasive terrigenous influx our data show that a very close correlation exists between 10be concentrations and the local proxy of rainfall rates and regimes pollen indicating that a considerable 10be transport from the mainland may occur in response to the remobilization of terrestrial reservoirs during periods of increased runoff superimposed is a dynamic oceanographic setting that further controls the preservation potential of 10be at the bottom in terms of changing water chemistry and or composition of the sedimentary flux to the seafloor results of our investigation suggest that in particular environmental and depositional settings the interplay between climate terrigenous yield and oceanography may jeopardize the sedimentary depiction of the meteoric 10be contribution thus challenging the use of 10be for tracking the stratigraphic position of geomagnetic reversals

a high resolution record of the matuyama brunhes transition from the mediterranean region the valle di manche section calabria southern italy abstract high resolution palaeomagnetic and rock magnetic investigations on the valle di manche section crotone basin calabria southern italy provide a detailed record of the matuyama brunhes m b reversal that to our best knowledge is the only available record of the last geomagnetic reversal for the mediterranean on land marine stratigraphy the m b transition can be pinpointed precisely as it develops within a 3 cm thick interval located just above a prominent tephra layer the pitagora ash where the sedimentation rates are about 27 cm kyr demagnetization analyses indicate a stable palaeomagnetic behaviour throughout the section for both normal and reversed polarity directions with demagnetization vectors aligned toward the origin of zijderveld diagrams after the removal of a small viscous low coercivity remanence component in the lower part of the studied interval some samples acquired a spurious gyromagnetic remanent magnetization grm during af demagnetization in high fields rock magnetic analyses confirm that magnetite is the main magnetic carrier for all measured specimens which also have an abundant paramagnetic fraction only the lower part of the record well below the m b boundary is characterized by a downward increasing presence of iron sulphides greigite according to our chronology which is based on a robust cross validated age model the final reverse to normal directional change of the m b transition occurred at ca 786 9 5 ka error includes uncertainty in orbital tuning and was very rapid of the order of 100 years or less

facies and cycle architecture of a pleistocene marine terrace crotone southern italy a sedimentary response to late quaternary high frequency glacio eustatic changes abstract cyclic late pleistocene shallow marine deposits such as those forming the sedimentary cover of some marine terraces allow a detailed study of the architecture of nearshore to offshore cycles deposited under the influence of high amplitude glacio eustatic changes the capo colonna marine terrace located near crotone southern italy is composed of two cycles recording a low frequency retrogradational trend which is thought to be the result of a generalized base level rise during a late pleistocene interglacial stage superimposed on regional uplift cycles of the capo colonna marine terrace are composed of coarse grained lags siliciclastic shoreface deposits and mostly carbonate shelf deposits and their general stratigraphic architecture evidences relatively thin transgressive and thick regressive intervals the latter can be top truncated due to wave ravinement during a subsequent erosional transgression the architectural style of the capo colonna marine terrace cycles is thought to be linked to very rapid base level rises related to the late pleistocene high amplitude glacio eustatic changes climatic variations controlling the sediment supply rate are considered less effective in the present context present results allow a comparison with other cyclic successions developed under icehouse climatic regimes showing a discrete variability in their stratal architecture

composite sedimentary record of falling stages of pleistocene glacio eustatic cycles in a shelf setting crotone basin south italy abstract a thick pleistocene shelf and nearshore cyclical succession was deposited in the s mauro sub basin of the crotone basin southern italy the regressive units of the cycles are mostly represented by coastal siliciclastic and bioclastic prograding wedges showing a clinoform geometry these are separated by blanket like deposits of high lateral persistence recording major transgressive episodes the aim of this paper is 1 to describe facies patterns and depositional setting of two prograding wedges particularly focussing on their polycyclic internal architecture 2 to analyze these units within a sequence stratigraphic framework and 3 to speculate on the possible origin of the small scale cyclicity the two wedges analyzed in this paper consist of a number of shingles individual shingles consist of two physically connected units 1 a relatively thin package of sigmoid clinoforms grading into 2 a volumetrically dominant package of oblique tangential clinoforms with toplap terminations the shingles are bounded by seaward dipping surfaces with sigmoid clinoform geometry which are ravinement surfaces updip passing into conformable flooding surfaces downdip the wedges are thus organized into high frequency small scale sequences each comprising transgressive highstand and falling stage systems tracts as a whole individual prograding wedges are interpreted as forced regressive units as the shoreline was subject to an overall shift basinwards and downwards along a low angle trajectory in spite of the repeated minor relative sea level rises tectonic subsidence and particularly the syndepositional growth of gentle synclines are thought to have been the key factors allowing the preservation of these forced regressive units progradation of the wedges took place in a high energy wave climate characterized by high frequency of storms and very efficient alongshore redistribution of sediments recurrent storm driven offshore currents led to intense reworking of sediments on the topset platform and gravity spreading on the foreset slope of the prograding wedges well oxygenated conditions over the shelf due to intensified storm activity during glacial periods may have enhanced the rate of production of skeletal foramol type carbonates it can reasonably be assumed that progradation took place from a line source and that the sand bodies are to be regarded as coastal prograding bodies in spite of active syndepositional tectonics the cycles can be correlated to pleistocene high amplitude sea level oscillations the older of the two wedges can be correlated through bio magnetostratigraphy to the major climatic transition which occurred from the marine oxygen isotope stage 25 to 24 22 rio et al 1996 the younger probably developed during the sea level fall that ended with substage 18 2 as suggested by sequence and bio stratigraphic data the prograding wedges are thus interpreted to record long lived sea level falls of fourth order cycles due to the particular depositional setting we are inclined to exclude authigenic mechanisms in the origin of small scale cyclicity although the concomitance and interaction of different controlling factors may be taken into account it is tempting to ascribe this cyclicity to minor eustatic changes punctuating long lived erratic falling stages possibly accompanied by climate driven fluctuations of sediment supply shelf perched and shelf edge prograding units consisting of foramol type carbonates are apparently a common falling stage to lowstand depositional feature in the mediterranean area during the late pliocene and pleistocene

pseudoconglomerate and a re examination of some paleoenvironmental controversies pseudoconglomerate an unusual fragmental rock that contains pebblelike clasts is described from the barberton greenstone belt south africa it occurs in concordant and discordant bodies that are closely associated with silicification carbonation and in situ brecciation and veining pseudoconglomerate is interpreted as a product of submarine exhalative activity in a hemipelagic environment it is thought to develop in subsurface breccia bodies that form by hydraulic disaggregation of the host rock breccia clasts are jostled during continued fluid flow and become rounded as the result of attrition between adjacent fragments the previous interpretation of this rock as a normal marine sediment at barberton and possibly in other archean and paleozoic sequences may have resulted in paleoenvironmental misinterpretation

paleoclimate controls on stratigraphic repetition of chemical and siliciclastic rocks climate is a primary control on sediment flux from continental sources into sedimentary systems in warm climates siliciclastic input is greatest under highly seasonal rainfall nonseasonal conditions favor formation of end member chemical rocks perennially wet climates are conducive to coal formation whereas dry climates produce carbonates and or evaporites stratigraphic repetition of siliciclastic and chemical rocks therefore appears to be related to paleoclimate cycles as well as to transgressive regressive events and tectonics

review and new aspects concerning the formation of eastern mediterranean sapropels abstract in this paper it is proposed that the formation of eastern mediterranean sapropels occurred in an anti estuarine type of circulation which was to some degree weakened relative to the present in response to reduction of the eastern mediterranean excess of evaporation over freshwater input this reduction of excess evaporation would have been imposed by intensifications of 1 the indian ocean summer sw monsoon influencing the eastern mediterranean via increased nile discharge and 2 the system of mediterranean depressions an element of the westerly atlantic system causing increased precipitation and decreased evaporation both the indian ocean summer monsoon and the westerly atlantic system would be intensified in response to the occurrence of distinct minima in the cycle of precession it is demonstrated that reduced excess evaporation whether or not coinciding with global phases of deglaciation would lead to reduction of surface water salinities in the eastern mediterranean causing isolation of previously formed high salinity cooler deep water thus mixing was severely reduced possibly even restricted to eddy diffusion with only occasional convective events that because of the existing density gradient hardly ever would reach the deepest parts of the basin the consequently diminished oxygen advection down from a few hundred meters in the water column favoured preservation of the sinking organic matter this would however suffice only to enable the formation of sapropels with low organic carbon contents the high organic carbon contents observed in various sapropels are argued to reflect superimposed increases of export production the described scenario accounts for previously reported 1 increases of organic carbon content with increasing depth of deposition within individual sapropels and 2 asymmetrical sequences of sapropel deposition characterized by gradual build up and rather abrupt ending it is furthermore in agreement with 3 isotopic and faunal reconstructions of the history of exchange transports through both the strait of sicily and the strait of gibraltar and 4 faunal and floral reflections of the presence or absence of a distinct deep chlorophyll maximum with its associated increases in export production indicating the presence or absence of a shallow pycnocline within the euphotic layer moreover the described scenario 5 is in no way conflicting with the reports of sapropels in the western mediterranean and 6 seems to be endorsed by occasionally intercalated intervals suggestive of somewhat improved oxygenation amidst anoxic benthic desert levels a situation that has been observed in a few quaternary and pliocene sapropels