how to interpret understand and predict stratal geometries using stratal control spaces and stratal control space trajectories interpreting and predicting basin margin stratal geometries requires understanding of controls such as variations in supply and accommodation ideally based on independent quantitative evidence stratal control spaces are a new tool to analyze controls on strata a stratal control space is an area volume or perhaps a higher dimensional space defined by a range of values of the controlling processes subsidence sediment supply and eustasy a three dimensional stratal control volume with axes of subsidence sediment supply and eustatic rates of change can be populated with probabilities derived from analysis of time series of subsidence supply and eustasy these empirical or theoretical probabilities indicate the likelihood of occurrence of any particular combination of control rates defined by any point in the volume the stratal control volume can then be analyzed to determine which parts of the volume represent relative sea level fall and rise where in the volume particular stacking patterns will occur and how probable those stacking patterns are for outcrop and subsurface analysis using a stratal control area with eustasy and subsidence combined on a relative sea level axis allows similar analysis and may be preferable a stratal control trajectory is a history of supply and accommodation rates interpreted from outcrop or subsurface data or observed in analogue and numerical experiments and plotted as a series of linked points forming a trajectory through a stratal control space two theoretical and one actual outcrop example are presented to demonstrate how stratal control trajectories can be analyzed to determine which controls are dominant the accommodation supply trajectory range ratio astrr is a useful metric to characterize trajectory geometry trajectories with astrr 1 can be considered accommodation dominated and astrr 1 indicates a supply dominated trajectory calculating the range of stratal control probabilities along the trajectory indicates the probability of the rates of change of subsidence supply and eustasy required to form the interpreted stratal geometry both types of stratal control trajectory analyses can provide important additional understanding and prediction of how why and where stratal geometries form

introduction to the future of sequence stratigraphy evolution or revolution sequence stratigraphy was first developed as concepts and methods from the late 19th to mid 20th century by geologists such as barrell and sloss it is now at the forefront of how sedimentary geologists observe record model and predict strata the geological society william smith meeting in burlington house in september 2014 considered the current state and future developments in sequence stratigraphy and focused particularly on how the subject should progress either by evolution or by revolution we feel that this is a relevant question because of continuing debate and in some cases controversy about what sequence stratigraphy is how we do it and what it can be used for for example one of the major hindrances to progress has been the interweaving of description and interpretation mixing method with model this has been pointed out and discussed by various researchers helland hansen gjelberg 1994 burgess prince in press this thematic set of papers presents a sample of the state of the art in sequence stratigraphy representing how the method and model is now being debated and developed from a plea to retain the earliest version of the concept to the inclusion of more radical ideas stimulated from experimental stratigraphy the 2014 william smith meeting was generously funded by bg group eni neftex sepm and the geological society of london we would also like to thank all the geological society staff who hosted and facilitated the meeting

accommodation and sediment supply controls on clastic parasequences a meta analysis this study combines data from many published case studies to undertake a quantitative characterization of clastic parasequences with the aim to determine how accommodation sediment supply and autogenic sediment storage dynamics are recorded in their sedimentary architecture and stacking patterns results of this study are used to critically evaluate the validity of paradigms and models that are routinely used to explain and predict trends in the anatomy and arrangement of parasequences data on 957 parasequences from 62 case studies of clastic shallow water successions were coded in a relational database which includes outcrop and subsurface datasets of ancient and quaternary examples these units cover the preserved records of both river dominated deltas and wave dominated coasts representing shoreline transits over a breadth of timescales likely of both local and regional extent the role of extant accommodation rates of creation of accommodation and rates of sediment supply in determining parasequence architecture is assessed through analysis of relationships between i proxies of these variables at different scales rates of aggradation and progradation facies belt shoreline trajectories systems tract type parasequence set stacking patterns parasequence progradation angle and stratigraphic rise size of feeder rivers and ii parameters that describe the geometry and stacking style of parasequences and associated shallow water sand bodies statistical analyses of database outputs indicate which proxies of accommodation sediment supply and accommodation sediment supply ratio are significant as predictors of parasequence architecture and allow for interpretations of the importance of allogenic and autogenic factors the principal results of this study reveal the following i parasequence thickness varies as a function of water depth accommodation generation and erosional truncation and these variations are also reflected across types of systems tracts and parasequence sets ii the dip length of parasequence sand bodies demonstrates scaling with measures of accommodation sediment supply ratio at multiple scales partly in relation to the possible effect of sediment supply on progradation rates iii in systems tracts stratigraphic trends in parasequence stacking due to autogenic mechanisms or to acceleration or deceleration in relative sea level fluctuations are not revealed quantitatively iv some association is seen between the abundance of deltaic or river dominated parasequences and progradational stacking v positive but modest correlation is observed between measures of river system size and the dip length of shallow marine parasequence sand bodies the resulting insights can be applied to guide sequence stratigraphic interpretations of the rock record and the characterization of sub seismic stratigraphic architectures of subsurface successions

from quantitative 3d seismic stratigraphy to sequence stratigraphy insights into the vertical and lateral variability of shelf margin depositional systems at different stratigraphic orders abstract a major challenge in sequence stratigraphy is objectively identifying stratigraphic surfaces and sequences across multiple scales of observation identification is commonly dependent on the resolution of the data used i e seismic vs well data its dimension i e 1d vs 2d vs 3d or the criteria chosen to select sequence boundaries through shelf edge trajectory analysis the clinothem i e highest order seismic sequence identified on seismic data can constitute the elementary building block of an observation based and data driven quantitative workflow to develop sequence stratigraphic frameworks across different orders and ranks of hierarchy here we use high quality 3d seismic data to interpret a late tithonian early cretaceous shelf margin the lower barrow group lbg developed in the northern carnarvon basin on the north west shelf of australia based on full volume seismic interpretation techniques that integrate the 3d variability of the data when identifying seismic unconformities a high resolution seismic stratigraphic framework was built 73 interpreted clinothems with an average time duration of 63 000 yrs the computation of high frequency shelf edge trajectory angle tse curves on selected seismic cross sections is used to objectively pick sequence stratigraphic surfaces based on the accommodation succession method thereby highlighting small changes in trajectory and proposing a method reproducible by interpreters based on the same quantitative data within the d lobispinosum interval 142 3 140 9 ma the definition of stratigraphic sequences and composite stratigraphic sequences through this workflow is used to discriminate the controls at high and low temporal frequency on the vertical and lateral variability which is here quantified of this shelf slope basin system the results show that the high frequency interplay between short term glacio eustasy i e milankovitch eccentricity cycles of 100 000 yrs and sediment supply locus of fluvial input along the margin impacted the three dimensional stratigraphic architecture of the lbg in contrast tectonic subsidence had a significant impact on the stratigraphic architecture of the lbg within the main depocentre at lower temporal frequency by overprinting the eustatic signal and accelerating decelerating the rates of accommodation creation however identification of long term glacio eustatic milankovitch cycles 400 000 yrs outside the main depocentre where the rates of accommodation creation due to rift related subsidence are moderate also suggests low frequency eustatic control therefore the vertical and lateral variability of the lbg results from variations in sediment supply and subsidence regime under local i e process regime currents regional i e tectonics and global i e eustasy climate forcing parameters interplaying across timescales in contrast to standard sequence stratigraphic workflows that are based on model dependent choices to select sequence boundaries quantitative 3d seismic stratigraphy constitutes an improved method to interpret 3d seismic data in shelf margin depositional systems within a sequence stratigraphic framework which provides an observation based and model independent tool allowing the definition of stratigraphic sequences with results that are reproducible across multiple stratigraphers this work highlights the need for developing new sequence stratigraphic tools and methods that integrate the 4d variability of depositional systems and moves beyond the two dimensionality inherent to current sequence stratigraphic methods quantitative 3d seismic stratigraphy represents a first step towards the creation of 3d sequence stratigraphic workflows that could improve the prediction of stratigraphic patterns and facies relationships source reservoir seal distribution across shelf margins

late messinian to early pliocene paleoenvironmental changes in the melilla basin ne morocco and their relation to mediterranean evolution abstract three major paleoenvironmental changes have been recognized during the late miocene to early pliocene in the melilla basin northeastern morocco and compared with the regional events that affected the mediterranean hydrology during this crucial period the first change was the definitive conversion of the restricted marine conditions that prevailed since the end of the reef carbonate complex into lacustrine environments this occurred around 5 8 ma which is earlier than in the rest of the mediterranean where the lower evaporites were still forming these lacustrine settings display great similarities with the lago mare environments that started in the mediterranean during the deposition of the upper evaporites and climaxed during the latest messinian the second change corresponds to a long period of subaerial exposure that caused a widespread erosional surface this resulted in a deep paleovalley which truncates the messinian sedimentary succession of the deeper southwestern part of the basin this event postdates a lava flow dated at 5 77 ma and confirms the importance of the latest messinian erosional event the third change was the infilling of this topography by marine sediments when the basin was rapidly reflooded in early pliocene the lack of evaporites indicates that the melilla basin did not experience the messinian salinity crisis this could be explained either by the drainage of the brines towards the deeper south alboran basin or rather by an early dilution of the basin due to local excess of continental water inputs while most of the other mediterranean basins evolved at the same time into evaporitic settings these data confirm that the rifian gateway was completely closed thus preventing atlantic water inputs in the mediterranean during the whole evaporitic deposition and the lago mare episode such an evolution fits well with the history of depositional environments in the alboran domain where evaporites are poorly developed and the messinian is mainly represented by an erosional surface

novel 3d sequence stratigraphic numerical model for syn rift basins analysing architectural responses to eustasy sedimentation and tectonics syn rift clastic sedimentary systems preserve a complicated stratigraphic architecture that records the interplay of tectonics eustatic sea level and storage and routing of sediments previous conceptual models describe and explain changes in depositional stacking patterns along a fault segment however stacking patterns and the nature of key stratigraphic surfaces is challenging to predict accurately with conventional sequence stratigraphic models that do not consider the three dimensional interplay of subsidence sedimentation and eustasy we present a novel geometric 3d sequence stratigraphic model syn strat which applies temporally and spatially variable fault scale tectonic constraints to stratigraphic forward modelling as well as allowing flexibility in the other controls in time and space syn strat generates a 3d graphical surface that represents accommodation although the model has the capacity to model footwall variation here we present model results from the hangingwall of a normal fault with temporal and spatial dip and strike predictions made of stacking patterns and systems tracts for a given set of controls sensitivity tests are tied to the depositional architecture of field based examples from the loreto basin gulf of california and alkyonides basin gulf of corinth here the relative influence of major sedimentary controls different subsidence histories varying sedimentation distribution including along strike variation in stacking patterns are assessed and demonstrate the potential of syn strat for reducing subsurface uncertainties by resolving multiple scenarios in addition the model demonstrates the nature of diachroneity of key stratigraphic surfaces that can arise in syn rift settings which could be represented by a bypass surface sequence boundary or reservoir seal maximum flooding surface in the rock record enabling a quantitative assessment of these surfaces is critical for prospect analysis in hangingwall half graben fills where these surfaces are heavily relied upon for well correlations that are used for hydrocarbon volume and production rate predictions

the cilicia adana basin complex eastern mediterranean neogene evolution of an active fore arc basin in an obliquely convergent margin abstract detailed interpretation of multi channel seismic reflection profiles showed that the deposition of the miocene successions in the cilicia adana basin complex occurred within a foredeep south of the arcuate tauride fold thrust belt the misis kyrenia fault zone defined the northernmost of a number of smaller thrust culminations developed within this foredeep fluvio deltaic successions suggest that the adana and inner cilicia basins became emergent during the tortonian when the western portion of the piggy back basin retained a marine connection the entire region became emergent during the messinian salinity crisis and up to 1000 m of evaporites were deposited in the cilicia and southern adana basins stratigraphic and structural relationships demonstrated that the late plio quaternary cilicia adana basin complex evolved as an asymmetric piggy back basin on the hanging wall of the large south verging misis kyrenia thrust culmination on the misis kyrenia segment of the culmination thrust activity ceased in early messinian whereas on the kyrenia segment it continued to the present the shift in the kinematics is expressed by the development of the ne sw trending steep faults with extensional separations bounding the plio quaternary depocentre in the adana and inner cilicia basins these basement rooted faults are incompatible with the contractional regime that existed in this part of the basin complex during the miocene in the outer cilicia basin the incompatibility between a domain of continued south directed fold thrust activity and uplift on the kyrenia range and a domain of extension associated with the development of plio quaternary depocentre indicates that strain is strongly partitioned across the e w trending southern basin bounding fault system along the southern margin of the outer cilicia basin progressive westward displacement of the tauride block within the aegean anatolian microplate created a localised transtensional regime within the inner cilicia and adana basins suggesting the presence of hard intra plate fault boundaries centred along the misis kyrenia horst block and the southern basin bounding fault system the northern basin bounding fault system including the kozan fault in the cilicia basin is a set of large antithetic structures linked to the master faults the westward pull out of the tauride block is related to the overall westward escape of the aegean anatolian microplate during the latest miocene to early pliocene whereas the continued contraction south of the basin complex across cyprus is related to the evolving collision and under plating of the continental micro fragment the eratosthenes we propose that the southern master fault of the outer cilicia basin primarily functions as a boundary separating a contractional microplate domain to the south from a transtensional microplate domain to the north

experimental measurement of the relative importance of controls on shoreline migration abstract shoreline position in sedimentary rocks is a sensitive recorder of the interplay of several controlling factors the most important of these are thought to be the stratigraphic trinity eustatic sea level subsidence and sediment supply in ancient rock sequences it is generally difficult to disentangle the effects of these variables here we analyze the relative influence of sea level subsidence sediment supply and other controlling variables on shoreline migration in an experimental basin equipped with a subsiding floor the experiment used a linear hinge type subsidence profile for which the rate was kept constant in time constant overall sediment supply and base level variation on two time scales that were first applied separately and then superimposed although base level was the only controlling variable that was externally varied in time the base level changes induced changes in other variables indirectly e g by changing the partitioning of sediment between the fluvial and offshore segments of the system we examine the relative importance of measured direct and indirect changes in all the governing variables through the use of a moving boundary equation for shoreline migration when measured values are used for all the variables in the equation shoreline migration rate throughout the run can be predicted with a maximum r2 of 0 92 starting with this optimal prediction of the observed shoreline behavior we successively replace variables in the equation with their run averaged values degrading the prediction the relative loss of prediction accuracy as each variable is replaced is a measure of the importance of that variable in accounting for the observed shoreline migration by this measure base level is the most important variable followed in turn by sediment supply to the foreset geometry of the foreset and the average subsidence rate over the foreset from the shoreline migration equation we also derive a quantitative version of the a s ratio often applied in sequence stratigraphy the new formulation reduces to a form comparable to the traditional descriptive a s ratio if changes in foreset slope gain or loss of sediment to the fluvial system and spatial variation in subsidence rate are all negligible

multi scale depositional successions in tectonic settings observations in sedimentary basins affected by deformation show that the fault induced depositional accommodation at various spatial and temporal scales is closely linked to basin kinematics the tectonically driven sediment infill displays the history of deepening and shoaling facies that are controlled by the activation of faults and changes in their offset rates simply stated this results in shifting sedimentary facies towards the source area or towards the basin centre in response to increasing or decreasing depositional space we propose a first principle conceptual model for tectonic successions controlled by the balance between the rates of creation of depositional space and sediment supply these sediment bodies are bounded by succession boundaries and comprise sourceward or basinward shifting facies tracts that are separated at a point of reversal due to the relatively steep slopes associated with the evolution of faults changes in sediment supply rates and mass wasting are common in these systems and may complicate the normal rhythm of the shifting facies tracts once tectonic quiescence is achieved and if the basin is connected to the open ocean eurybatic or eustatic base level changes may take over and play a greater role in sedimentary rhythm and cyclicity we illustrate the efficacy of the new concept with a review of examples from extensional contractional and strike slip basins we show that the basic tectonic succession model is applicable at all temporal and spatial scales and whether the tectonics cause subsidence or uplift and in all types of tectonic settings that determine the evolution of sedimentary basins

review of the late quaternary stratigraphy of the northern gulf of cadiz continental margin new insights into controlling factors and global implications abstract over the past decades the northern gulf of cadiz has been the focus of a wide range of late quaternary seismic and sequence stratigraphic studies either addressing the slope contourite depositional system cds or the development of the continental shelf yet high resolution seismic data bridging between these domains and age information have remained sparse this study based on new high resolution reflection seismic profiles calibrated to iodp expedition 339 sites u1386 u1387 now presents an updated stratigraphic framework that integrates for the first time the late quaternary records of the northern gulf of cadiz middle slope to shelf off the guadiana river seismic stratigraphic analysis of the stacking depocenter distribution stratal architecture and facies of the seismic sub units reveals the influence of 100 kyr sea level variations paced by milankovitch eccentricity cycles tectonics manifesting as two pulses of uplift and margin progradation sediment supply and bottom current activity this work furthermore contributes to the application and understanding of high resolution late quaternary sequence stratigraphy firstly the proposed sequence stratigraphic interpretation shows that adaptations to the basic models are required to integrate the shelf and slope record and to account for the presence of a significant alongslope bottom current controlled component secondly the results confirm that the sequences are dominantly composed of regressive deposits whereas the preservation of transgressive to highstand deposits is more irregular significantly the common assumption that successive major glacial lowstands are consistently recorded as well marked shelf wide erosional unconformities is demonstrated to be occasionally invalid as tectonics can obliterate this one to one relationship

tectonic development of the eastern mediterranean region the eastern mediterranean region is a classic area for the study of tectonic processes and settings related to the development of the tethyan orogenic belt the present set of research and synthesis papers by earth scientist from countries in this region and others provides an up to date interdisciplinary overview of the tectonic development of the eastern mediterrenean region from precambrian to recent key topics include continental rifting ophiolite genesis and emplacement continental collision extensional tectonics crustal exhumation and intraplate deformation e g active faulting alternative tectonic reconstructions of the tethyan orogen are presented and discussed with important implications for other regions of the world the book will be an essential source of information and interpretation for academic researchers geologists and geophysicists advanced undergraduates and also for industry professionals including those concerned with hydrocarbons minerals and geological hazards e g earthquakes

salt tectonics in two convergent margin basins of the cyprus arc northeastern mediterranean abstract seismic reflection profiles from the adana cilicia and iskenderun latakia basin complexes in the ne mediterranean sea show the presence of linked extensional contractional fault systems detached at the base of the messinian evaporites the extensional domain is developed within the thick proximal part of the plio quaternary delta succession in the inner part of each basin it is characterized by imbricate fans of listric normal faults which delineate turtle anticlines and their intervening syncline the faults sole into the gently southwest dipping detachment surface in the inner basins salt is largely evacuated toward the outer basins but remnants occur as rollers in the footwalls of the listric extensional faults and small subdued pillows beneath turtle anticlines the narrow synclines between the two turtle back growth anticlines record a more complicated history of rise and fall of the salt related to switch in vergence of the extensional fault fan a large salt wall is developed at the toe of the delta complex in both basins two wide peripheral sinks are present within the plio quaternary units on both flanks of the salt wall locally small segments of salt welds are present near the base of the salt wall the contractional domain is characterized by a relatively thin plio quaternary cover overlying a relatively uniform 500 800 ms thick salt substrate a series of salt cored growth folds are commonly associated with thrusts of variable vergence the halokinetic structures in the cilicia and latakia basins display a remarkable resemblance to detached and linked systems of extensional and contractional fault fans documented in classical salt provinces on passive margins the study area also resembles scaled experiments which document synchronous development of extensional and contractional fault systems detached in a ductile substrate however a number of differences also exist which may arise from several factors including the nature of ductility contrast between the ductile portion of the evaporite layer and the supra salt succession the thickness ratio of overburden to evaporite unit and the rate of progradation and the nature of sediment distribution during the evolution of the delta complex the special aspect of these associations of linked gravity driven extensional and contractional salt structures is that they are developed as a self contained system wholly situated within a plio quaternary transtensional basin

resedimentation of basin centre sulphate deposits middle miocene badenian of carpathian foredeep southern poland abstract the middle badenian anhydrite sections in the central part of the carpathian foredeep consist mainly of interbedded laminated anhydrite and anhydrite breccia these facies display features characteristic of redeposited sediments such as distortions due to slumping erosional boundaries and graded bedded laminae lamination in laminated anhydrite is rarely regular and often accompanied by disruptions the predominance of clasts of laminated anhydrite combined with the observed brecciation of laminated anhydrite indicates that a short distance for transport and even in situ reworking were common a high degree of convolution indicates that some reworked sediments were unconsolidated when they moved but in many cases they were probably at least partly lithified this is evidenced by the anhydrite breccia consisting of clasts of laminated anhydrite as well as the brecciation in situ the resedimentation processes have not been related to regional bathymetrical differences as indicated by minor differences along seismic profiles a great deal of redeposition within the basin centre of the middle badenian evaporite basin combined with the in situ brecciation suggests that the triggering mechanism for redeposition could be earthquakes they generated mass flows and eventually turbidites so that earlier deposited grains could be redeposited this implies that in other evaporite basins the laminar facies might be at least partly related to redeposition and not necessarily to changes of surface brine concentration as usually supposed

sea level changes an integrated approach sea level changes an integrated approach in october 1985 sepm sponsored a four day conference entitled sea level changes an integrated approach the purpose of the conference was to provide a forum for an interdisciplinary exchange of ideas on sea level changes and to provide an opportunity for integrating various types of evidence in approaching unresolved issues the conference was successful in bringing together scientists from industry academia and government representing all of the major geosciences disciplines presentations of many new papers plus significant releases of data that were previously held proprietary provided fertile ground for discussion this much cited volume represents the best of the material presented at the conference includes the early vail chart

anhydrite diagenesis in a vegetated sabkha al khiran kuwait arabian gulf abstract in the al khiran sabkha supratidal anhydrite occurs in three distinct morphological forms a hair cream anhydrite which occurs exclusively in association with the halophyte halocnemum strobilaceum and b nodular laminated cottage cheese anhydrite which is associated with a bacterial cyanobacterial mat the former occurs as a massive layer up to 4 cm thick with the ahydrite initially pseudomorphing gypsum crystals while in the latter the layers are up to 7 cm thick and the anhydrite occurs as microcrystalline laths giving an aphanitic texture c sub aqueous anhydrite formed by the alteration of prismatic gypsum crystals growing in drainage channels on the death of the halophyte the gypsum g rlhar2 anhydrite a metastable equilibrium is upset and the hair cream anhydrite undergoes a reverse transformation to microcrystalline alabastrine secondary gypsum followed by gypcrust formation the above changes result in a series of characteristic diagenetic textures that were studied in detail by scanning electron microscopy sem the major diagenetic mechanism during the g rlhar2 a transformation is a dissolution reprecipitation process that is only partially controlled by physico chemical factors a climatic and biological influence also plays a significant role in this sometimes annual change depending on the rainfall intensity in contrast type b shows better preservation potential the intimate relationship between the plant and its soil water requirements results in a particular hydrodynamic behaviour of the capillary groundwater brines in the vadose zone hence it is inferred that the individual diagenetic stages are also correlatable with the changing hydrological conditions of the sabkha type c represents a rare occurrence in sabkhas and is more akin to some deeper water occurrences albeit on a very small scale anhydrite is always formed after a gypsum precursor and under predictable physico chemical conditions an average annual temperature of 30 c and brine chlorinity of 4 mol cl kg 1 although it is confined to the vegetated zone of the marine sabkha stable isotope analysis indicates a dominantly continental origin for the groundwaters and coexisting sulphate minerals on a regional scale the vegetated kuwait sabkhas appear to occupy a climatic position intermediate between the classic uae sabkhas and those of the mediterranean region al khiran is the northernmost limit of the evaporite belt containing anhydrite in the arabian gulf the palaeoclimatic and sedimentological implications of this distribution may be of potential value in the rock record

three dimensional seismic sedimentology and stratigraphic architecture of prograding clinoforms central taranaki basin new zealand three dimensional 3d seismic reflection analysis of a major miocene to pleistocene c 19 2 ma clinoform succession of the central taranaki basin offshore new zealand reveals two distinct intervals of downbuilding progradation c 7 5 6 ma and c 4 2 ma downbuilding clinoforms are of kilometre scale and characterized by straight upper foreset gullies that initiate near or at the clinoform breakpoint in places connected to topset distributary channels foreset mass transport complexes occur mainly in the basal parts of downbuilding clinoform successions upbuilding progradational clinoforms formed between c 6 5 5 ma and c 4 5 4 ma these clinoforms are generally smaller with topsets in places comprising beach ridges and tidal channels the foresets of the upbuilding clinoforms contain large gullies and sinuous deepwater channels locally connected to topset channels retrogradational deposits in the studied succession c 5 5 4 5 ma lack a distinct clinoform geometry show a few slope channels and gullies and are characterized by extensive landward stepping networks of shallow marine and fluvial channels 3d seismic reflection analysis of the c 2000 km2 study area allows an exemplary 3d documentation of migrating depositional systems along a highly progradational clastic margin constrained by a stratigraphic framework tightly defined by the two intervals of major depositional downbuilding the late miocene downbuilding is interpreted as forced by tectonic uplift along the cape egmont fault and neighbouring structures in the south of the study area in contrast the plio pleistocene downbuilding is interpreted as dominantly controlled by eustasy in a tectonic environment characterized by subsidence excellent preservation of the 4 2 ma clinoform topsets provides unique insights into depositional systems at and above the shelf break imaging palaeo shoreline and palaeo backshore environments the detailed 3d clinoform analyses presented contribute to the understanding of clastic sedimentation processes from shelf to slope which can be used to predict deepwater depositional facies

the onset of the messinian salinity crisis in the eastern mediterranean pissouri basin cyprus the pissouri basin in cyprus contains one of the most suitable sedimentary successions with which to study the onset of the messinian salinity crisis in the eastern mediterranean exposures along the new paphos limassol motorway near pissouri exhibit distinct cyclic bedding which permits the construction of a chronology based on orbital tuning biostratigraphic results reveal 10 planktonic foraminifera events that have been astronomically dated in other mediterranean sections and as such provide an excellent first order age control magnetostratigraphic results are in good agreement with the biostratigraphic data and show that all magnetic chrons between c4n 1n and c3an 1n are present the pattern of sedimentary cycles generally fits well with the insolation curve astronomical tuning of the succession shows that the first gypsum bed at pissouri overlies a 40 60 kyr stromatolite bearing transitional interval and correlates with the amplitude increase in insolation at 5 96 ma as in the western mediterranean this indicates that the onset of evaporite precipitation was synchronous right across the entire mediterranean basin fl 2002 elsevier science b v all rights reserved

sedimentology of badenian middle miocene gypsum in eastern galicia podolia and bukovina west ukraine primary gypsum is the main evaporite mineral in the middle miocene badenian of the west ukraine the lower part of the gypsum sequence is built of autochthonous gypsum while the upper part is composed of allochthonous gypsum that formed following a major tectonically induced change in basin morphology this change resulted in the destruction of the gypsum deposited on the margins of the basin and formation of redeposition features autochthonous gypsum facies were deposited in two main environments 1 giant gypsum intergrowths precipitated from highly concentrated brines 2 very shallow subaqueous gypsum deposited in a vast brine pan the brine pan was characterized by a facies mosaic that reflects an interplay of concentrated brines from the central part of the evaporite basin and diluted brines due to the influx of continental meteoric waters the facies continuum microbial gypsum bedded selenite massive selenite sabre gypsum indicates increasing salinity of the brine with time this type of facies pattern has been established in recent salinas that are analogous to badenian gypsum in their lateral facies changes however the pattern of facies distribution with respect to the open sea in the badenian basin is opposite to that found in recent salinas the pattern of the badenian gypsum facies in the ukraine indicates that facies repetition may have been related to climatically controlled salinity changes and not to depth changes as is commonly used to explain the repetition of sulphate facies in a vertical succession

variable response of coastal environments of the northwestern gulf of mexico to sea level rise and climate change implications for future change the results from nearly three decades of marine geological research in the northwestern gulf of mexico are compiled in an effort to understand those factors e g sea level rise sediment supply subsidence antecedent topography that influenced coastal evolution during the last eustatic cycle 120 ka to present armed with this information we evaluate coastal response to variable sea level rise of the holocene and accelerated rise during historical time to gain a better understanding of how the coast is likely to respond to future changes the early holocene evolution of northwestern gulf of mexico bays was punctuated by rapid and possibly synchronous flooding events that are interpreted as resulting from episodes of rapid sea level rise two of these events one between 8 4 and 8 0 ka and the other between 7 4 and 6 8 ka were associated with known episodes of ice sheet retreat in north america and antarctica respectively during the middle and late holocene the east texas and western louisiana coasts experienced episodes of stability and growth followed by rapid shoreline retreat while the central texas coast remained relatively stable this variability in coastal response to sea level rise resulted mainly from differences in sediment supply and the highly irregular antecedent topography on which coastal environments formed sand that nourished the evolving east and south texas as well as westernmost louisiana coasts was derived mainly from transgressive ravinement of deltas that were formed during the falling stage of sea level mis5e mis2 the loci of these deltas controlled the spatial variability of this offshore sand supply sand supply to the central texas coast has been dominated by converging longshore currents and throughout the middle to late holocene was large enough to keep pace with sea level rise moreover sand supply from rivers has varied considerably in response to climate change during the early holocene when the average rate of linear sea level rise was 4 2 mm yr the brazos colorado and rio grande rivers all formed deltas on the inner continental shelf today only the brazos contributes enough sediment to the gulf of mexico to form a delta but its sand delivery is minimal a reversal from late holocene growth of western louisiana east texas and south texas barrier islands and peninsulas to erosion occurred during the last 2 0 ka after the rate of sea level rise began to decelerate the actual timing of this reversal was diachronous across the coast and was caused by a decrease in sediment supply once offshore sand sources were bypassed by the landward advancing shoreface transgressive ravinement differences in the exact timing and rate of retreat also reflect variability in the offshore profiles of these barriers and their thickness which results from the underlying relief on the pleistocene surface the late holocene was also the time of chenier plain development in western louisiana and east texas that was marked by localized differences in growth and retreat the current rate of eustatic sea level rise in the northern gulf of mexico is in the range of 2 0 and 3 0 mm yr and is approaching rates of the early holocene this is on average about five times the long term rate of the past 4 0 ka this larger rate is associated with an increase in coastal erosion in historical time relative to long term rates current rates of gulf shoreline erosion are approaching rates of the early to mid holocene and the rate of retreat of some barriers is not sustainable core transects off central texas reflect a late holocene history of shoreface progradation but the modern shoreline is currently eroding albeit at slower rates than elsewhere along the coast overall the sand supply needed to sustain the gulf shoreline is lacking likewise baylines are experiencing erosion rates that are faster than the late holocene average and bayhead deltas are at the tipping point of catastrophic retreat spatial variability in erosion rates highlights the importance of factors such as sediment supply subsidence and anthropogenic influences on coastal evolution tropical storms and hurricanes while exerting the most noticeable coastal change merely exacerbate overall shoreline retreat and migration along the entire northwestern gulf coast the impact of human intervention to natural processes is particularly evident primarily due to alterations in river discharge and sediment supply to the coast interruptions in along shore and cross shore sand transport and increases in rates of subsidence through fluid withdrawal compared to natural changes that took place during the holocene the impacts of human activity have been virtually instantaneous the geological record indicates that the ongoing increase in the rate of sea level rise coupled with diminished sediment supply and human intervention will continue to severely impact the low gradient coastal environments of the northwestern gulf of mexico

practical problems in the application of the sequence stratigraphic method and key surfaces integrating observations from ancient fluvial deltaic wedges with quaternary and modelling studies sequence stratigraphy solved the basic problem that genetically related but different lithofacies were routinely assigned to different lithostratigraphic units defined by arbitrary vertical and horizontal cutoffs stratigraphically important stratal relationships and especially stratal terminations for example lapout can be observed in seismic data and can be documented in continuous outcrops such as in the deserts of the western interior of north america and in closely spaced well log data sets in sparse data sets interpolation of lapout patterns introduces uncertainty in correlation and designation of sequences and systems tracts and their associated surfaces diachroneity of fluvial terrace deposits is documented using detailed facies architectural studies and calls into question the assumed chronostratigraphic significance of many so called sequence boundaries identified in the rocks of the cretaceous interior seaway of north america sequence boundaries formed during prolonged sea level falls may be less chronostratigraphically significant than transgressive surfaces formed during rapid rises as a consequence flooding surfaces are theoretically more significant and also have greater utility as allostratigraphic boundaries although they may also exhibit diachroneity tectonic unconformities produce differential lithospheric deformation which results in angular unconformities although the angle of discordance may be very small in the cretaceous interior seaway of north america such unconformities may be expressed by marine erosion in distal basin settings regional isochronous bentonites provide useful marker beds that clearly illustrate angular discordance in the fluvial realm such tectonic discontinuities may be indicated by changes in palaeocurrent orientations as well as by provenance changes although sequence stratigraphy provides a powerful methodology and theoretical framework for correlating and understanding the evolution of stratigraphic successions in the context of changing accommodation allostratigraphy remains the only accepted scheme for the formal naming of stratigraphic units based on bounding discontinuities whatever type of sequence stratigraphy or allostratigraphy is preferred in all cases it is key to recognize that sequence stratigraphy at its heart is the re ordering correlation and sometimes renaming of stratigraphic units on the basis of bounding discontinuities and their correlative surfaces as opposed to the arbitrary lithofacies oriented approach using broad facies zones for example shazam lines or arbitrary cutoffs such as is used in traditional lithostratigraphy

contributions to sequence stratigraphy from analogue and numerical experiments the sequence stratigraphic model although no longer focused on eustasy and accommodation has been until recently based largely on observation and interpretation of outcrop and subsurface data this approach may be restrictive if the current model places limits on what is observed and how observations are interpreted to make progress in our understanding of strata the sequence stratigraphic model and method should be tested against and fully incorporate theoretical and experimental results that provide new knowledge of 1 autogenesis 2 intrinsic stratigraphic responses 3 alluvial grade and 4 scales appropriate to single depositional systems evolving with relative sea level changes more extensive inclusion of analogue and numerical experimental results could lead to significant modification and refinement of existing sequence stratigraphic models

forced regressions in a sequence stratigraphic framework concepts examples and exploration significance sequence stratigraphic concepts suggest that stratal geometries develop and are largely controlled by changes in relative sea level on the shelf lowstand deposits which form during falls and subsequent stillstands of relative sea level can be recognized by the presence of an unconformity at the base the isolated and basinward position relative to the previous shoreline and the abrupt seaward translation of shallow water and shoreline facies into the basin across an unconformity surface this seaward translation of facies and shoreline regression in response to relative sea level lowering is termed a forced regression a forced regression is independent of variations of sediment flux and is in contrast with normal regressions that occur in response to excess sediment flux relative to space available on the shelf i e accommodation forced regressions commonly are associated with a zone of sedimentary bypass subaerial exposure and possible fluvial erosion between the newly formed and preceding shorelines certain shelf sands previously interpreted as offshore or mid shelf sand bodies thus can be reinterpreted as stranded lowstand shorelines associated with forced regressions this alternative interpretation has economic significance insofar as it suggests different subsurface correlations and reservoir geometries with the potential for development of new play types and enhanced recovery in o der fields examples of forced regression can be observed at a variety of scales and ages several such examples include the modern east coulee fan delta and the lower cretaceous viking formation in alberta canada the quaternary rhone delta and the quaternary hudson valley system

reappraisal of the sequence boundary in time and space case and considerations for an su subaerial unconformity that is not a sediment bypass surface a time barrier or an unconformity abstract the sequence bounding unconformity bears the key defining traits of being a surface separating younger from older strata along which there is evidence of subaerial erosional truncation or subaerial exposure with a significant hiatus indicated van wagoner et al 1988 this subaerial component of sequence boundaries subaerial unconformity su is also broadly considered to form as a topographic surface of sediment bypass carved during relative sea level fall and buried by backfilling during relative sea level rise accordingly the su is commonly presumed to record an approximate time barrier which separates older from younger strata along its full length in this paper we show that regional composite scour rcs surfaces that are traditionally mapped as an integral component of the su were never a single subaerial topographic surface characterized by sediment bypass are not unconformities do not record an effective time barrier and form diachronously at the channel belt scale over the entire fall to rise of a base level cycle these rcs surfaces and by inference the su surfaces they comprise thus do not fully fit key defining characteristics embodied in the conceptual sequence boundary flume observations and field data show that the rcs is buried by fluvial sediment simultaneously as it is scoured accordingly the rcs is perennially covered with stored sediment during formation is only exposed as a subaerial topographic surface at the local place and time where it is undergoing active growth and forms over the duration of local marine drainage during a relative sea level cycle this cut and cover model differs greatly from more established bypass models which assume that the rcs was roughly sediment free and subaerially exposed for long durations of incision during regression and thus preserves a significant depositional hiatus upon later burial instead the rcs may commonly and locally record a hiatus more typical of a facies bounding diastem without a lacuna significantly greater than that of surfaces within the strata it binds fragments of fluvial strata may commonly and sporadically be preserved above the rcs that are older than underlying marine units overrun by this surface consequently the rcs is not an effective time barrier lateral planation by migrating and avulsing channels as the rcs expands laterally after nucleation can place younger fluvial strata over much older units which means that this surface is also composite and highly diachronous laterally at the scale of channel belts the cut and cover model has additional implications not captured by the bypass model first significant sediments may be stored within fluvial strata above the rcs during regression that are not available for contemporary falling stage and lowstand marine shorelines this can result in marine sediment starvation particularly of the sand fraction and in extreme cases can result in sand autodetachment and an absence of regressive marine reservoir sandstones second cutting of the rcs co generates a suprafluvial surface above the covering fluvial strata during regression that may be used as a mappable proxy for the conceptual maximum regressive surface mrs the mrs may be raised above this surface locally by low accommodation aggradation during lowstand normal regression but in either case preserves an approximate time line where not reworked during later transgression third valley development across the rcs does not exclusively form by landward knickpoint growth and may include complexly formed and potentially cross cutting buffer valleys su valley incision can be divided into four modes which include denudation structural buttress and buffer valley components which may work together locally and tend to have variable importance along the shore to hinterland profile although the rcs is not a good rock proxy for the conceptual sequence boundary it remains a very mappable surface which may separate facies of potentially very different origin and reservoir quality the rcs is also inseparable from the su and typically the only terrestrial erosional surface of extent in most short duration sequences its nullification as a sequence boundary would mean abandonment of depositional sequence stratigraphy as a correlation and interpretive tool within these sections an alternative to abandonment of the su as a sequence boundary is to loosen the definition of a sequence boundary to a discrete surface of erosional truncation carved landward of contemporary shorelines that is traceable beyond the scale of a single valley or comparable local system and its correlative surfaces of conformity and or non deposition and continue its use as before

how much systems tract scale three dimensional stratigraphic variability is present in sequence stratigraphy an answer from the middle miocene pearl river mouth basin prior sequence stratigraphic methods mainly employed two dimensional 2 d stacking patterns to reconstruct stratigraphic frameworks the future of sequence stratigraphy will pay more attention to systems tracts scale and three dimensional 3 d stratigraphic variability using 1 2 104 km2 4 63 103 mi2 3 d seismic data tied to regional 2 d seismic lines and 21 boreholes the present study examines systems tract scale and 3 d stratigraphic variability of the 14 8 13 8 ma pearl river shelf margin to deep water sedimentary prisms the studied prisms were divided into four main systems tracts namely highstand systems tract hst falling stage systems tract fsst lowstand systems tract lst and transgressive systems tract tst each systems tract is represented by a given clinoformal architecture and stacking pattern 1 clinothem sets with aggradation to progradation are hst 2 clinothem sets with progradation to degradation pd are fsst 3 clinothem sets with progradation to aggradation pa are lst and 4 clinothem sets with retrogradation are tst lst or hst in addition pearl river fsst and lst display downdip stratigraphic variabilities which are regionally manifested in at least three ways 1 shelf edge deltas linked downdip to basin floor fans 2 shelf edge deltas linked downdip without fans and 3 basin floor fans linked updip that lack deltas in along strike orientation the pearl river fsst could exhibit low angle progradation not just pd stacking the lst could present retrogradational stacking not just pa stacking therefore the physical position of a systems tract is reemphasized in terms of assigning a given systems tract the concepts of three systems tracts are then revised for chronostratigraphic significance the lst is the lowermost systems tract of a sequence presenting a normal regression of the shoreline as its diagnostic characteristic and including contemporaneous stratigraphic units laterally the hst is the upper systems tract of a sequence providing a normal regression of the shoreline as its diagnostic characteristic and including contemporaneous stratigraphic units laterally the tst is the middle systems tract of a sequence generating a backstep of the shoreline and excluding contemporaneous onlapping units of both the lst and hst laterally the fsst has not been revised because fsst may be a supply independent feature

late miocene events in the mediterranean as recorded by carbonate evaporice relations the messinian stage in the mediterranean region is known mainly because of a major evaporitic event whose causes and global implications are still under discussion correlations between basinal evaporite bearing series and marginal carbonate platforms allow for improvement of the classical depostional models especially concerning the eustatic control of the environmental changes in the mediterranean these changes were controlled by the interplay of aperiodic and periodic factors 1 tectonics related to the relative motions of the african and eurasian plates and resultant linear increase in the basin restriction 2 sea level fluctuations that alternately aggravated the restriction or allowed marine replenishment and 3 climatic fluctuations that controlled the level of the mediterranean during stages of isolation the messinian sedimentary succession reflects a typical sequence of progressive isolation marine marls yields laminites yields transitional deposits yields evaporites yields lacustrine deposits the first stage of the so called salinity crisis was characterized by a mediterranean lowstand that resulted in erosion of former platforms and deposition of the lower evaporites during the next stage sea level rose tb3 3 cycle high enough to temporarily replenish the basin cyclic upper evaporites with development of stromatolite rich deposits finally the uppermost messinian freshwater to brackish lacustrine deposits reflect both themore cessation of sea water input maximum tectonic isolation low sea level and freshwater input related to increasing runoff less

varying tectonic control on basin development at an active microplate margin latakia basin eastern mediterranean abstract detailed interpretation of multichannel seismic reflection profiles show that the latakia basin evolved in two distinct tectonic stages southeast directed contraction that culminated in the latest miocene followed in the early middle pliocene by progressive transition to partitioned contraction and extension related to the initiation of strike slip along the eastern anatolian transform fault and its marine extensions the miocene fold thrust belt comprises two arcuate culminations enclosing a miocene piggy back depocentre situated on the backlimb of the amanos larnaka ramp anticline in the early middle miocene this piggy back basin was part of a much wider foredeep that also encompassed the miocene successions of the cilicia adana basin complex to the north the misis kyrenia fold thrust belt evolved in the tortonian effectively dividing the foredeep into two large piggy back basins our data demonstrate that a fundamental change in kinematic regime occurred during the messinian to early pliocene involving the onset of strike slip movements resulting in transtension along the northeast trending portion of the main lineaments bounding the latakia basin and continued contraction across the east trending portion of the lineaments in the northeastern portion of the latakia basin southeast directed thrusting ceased in the early messinian and was followed in the lower pliocene by the development of horst and grabzen structures bounded by faults linking onland with the strands of the east anatolian transform fault

new evidence and model on the evolution of the southeast anatolian orogen this paper describes the orogenic evolution of the southeast anatolian orogenic belt based mostly on new geologic data collected from its constituent tectonic units in the course of new mapping programs of the past decade the southeast anatolian orogenic segment of the alpides may be divided into three approximately east west trending zones from south to north they are the arabian platform followed by a zone of imbrication and then a zone of nappes the arabian platform includes a mostly marine sedimentary succession deposited from early cambrian to middle miocene time the zone of imbrication is a narrow belt sandwiched between the arabian platform and the zone of nappes it consists of imbricated thrust slices emplaced onto a late cretaceous to early miocene sequence the zone of nappes is the highest tectonic unit consisting of two stacks of nappes simply designated the lower and upper nappes the lower nappe is represented by the slices of a polyphase metamorpbic ophiolitic assemblage and the maden group the upper nappe rests on the lower nappe and is represented by the bitlis and poturge metamorphic massifs southeastern anatolia underwent two major episodes of alpide deformation the first occurred during the late cretaceous period when ophiolite was emplaced on the arabian platform this event was not the consequence of a continental collision the ophiolite obduction onto the arabian platform was followed by a regionwide extension and a new marine transgression over the platform immediately after the ophiolite obduction the second episode of deformation occurred during middle eocene miocene time in two distinct stages as a result of the progressive elimination and complete closure of the ocean s which led to the collision between the zone of nappes located to the north being a part of eurasia and the arabian plate the maden marginal basin formed north of the subduction zone that eliminated the ocean between eurasia and arabia along the southern margin of the taurus belt and abutted the arabian plate much later during the final collision the second episode of deformation formed the present orogenic segment leading to the amalgamation of different tectonic units these amalgamated nappes collided with the arabian plate and welded onto it at the latest stage of the orogenic evolution during the miocene epoch

quantitative models of sedimentary basin filling summary quantitative modelling of the filling of sedimentary basins was begun in earnest in the 1960s dozens of themes and variations have been proposed since then and have yielded an abundance of idealized stratigraphic patterns as functions of both imposed changes and basin properties post plate tectonic modelling began with rigid lid models which show the stratigraphic signature of subsidence variation this work introduced the connection between stratigraphy and the rheology of the lithosphere rigid lid models are the simplest type of geometric model in which the sediment surface is assigned prescribed geometries usually corresponding to different depositional environments these can reproduce many aspects of overall stratal geometry but are formally restricted to relatively long timescales for which quasi steady surface topography can be assumed so called dynamic models attempt to represent the morphodynamics of the sediment surface by abstracting and averaging short term transport processes most of the dynamic models proposed to date can be seen as special cases of a single general morpho dynamic equation the most important result of the first wave of quantitative basin filling models is that even relatively simple models can produce reasonable stratal patterns we now have a wide array of tools for exploring scenarios searching for general behaviours and effects and making initial quantitative predictions we have also learned that basin response to external forcing as recorded in stratigraphy can be as sensitive to the characteristics of the basin as to the forcing the main brake on the development of basin modelling is not computing power but lack of methods and data for testing the models we have already developed physical experiments which are only just beginning are one means of doing this experimental stratigraphy is a bridge to quantitative field tests which will require collaboration among academic researchers from a wide range of areas and between academia and industry on projects of greater scale and degree of integration than we have seen so far the advancement of quantitative sedimentary geology will also require significant changes in the way the subject is taught at all levels

sequence stratigraphy of experimental strata under known conditions of differential subsidence and variable base level sequence stratigraphy has been applied from reservoir to continental scales providing a scale independent model for predicting the spatial arrangement of depositional elements we examine experimental strata deposited in the experimental earthscape facility at st anthony falls laboratory focusing on stratigraphic surfaces defined by discordant contact geometries surfaces analogous to those delineated in the original work on seismic sequence stratigraphy in this controlled setting we directly evaluate critical sequence stratigraphic issues such as stratigraphic horizon development and time significance as well as the internal geometry and migration of the bounded strata against the known boundary conditions and depositional history four key stratigraphic disconformities defined by marine downlap marine onlap fluvial erosion and fluvial onlap are mapped and vary greatly in their relative degree of time transgression marine onlap and downlap contacts closely parallel topographic surfaces time surfaces and prior to burial approximate the instantaneous offshore topography these stratal bounding surfaces are also robust stratigraphic signals of relative base level fall and rise respectively marine onlap surfaces are of special interest they tend to be the best preserved discordance where widespread allogenic based onlap surfaces subdivide otherwise amalgamated depositional cycles amidst cryptic stacks of marine foresets however local autogenic based marine onlap discordances are present throughout the fill a critical distinguishing feature of allogenic onlap is the greater lateral persistence of the discordance surfaces defined by subaerial erosional truncation and fluvial onlap do not have geomorphic equivalence because channel processes continually modify the surface as the stratigraphic horizons are forming hence they are strongly time transgressive last the stacking arrangement of the preserved bounded strata is found to be a good time averaged representation of the mass balance history

origin and age of the mediterranean messinian evaporites implications from sr isotopes strontium isotope ratios from the messinian late miocene 6 4 to 4 85 ma evaporites of the mediterranean basin 1 2 support a subdivision into stratigraphically lower predominantly marine deposits lower evaporites lev lower gypsum and main salt characterized by sr isotopic ratios generally equivalent to those of messinian seawater and stratigraphically higher deposits upper evaporites uev with 87sr 86sr ratios lower than messinian seawater the range of 87sr 86sr ratios of the lev unit from the eastern mediterranean overlap with values obtained from essentially coeval red sea evaporites 3 strontium isotopic ratios measured from the upper evaporites however are lower and a high proportion of this sr was probably derived from low 87sr 86sr continental runoff that characterizes much of this basin 4 these results therefore strongly support depositional models utilizing a deep desiccated basin 1 with a constant marine inflow during the early stages including salt formation followed by a series of long lasting and sometimes isolated desiccation events that produced a strong but variable continental influence on the sr isotopic compositions of the uev strontium isotopic measurements can also be used to asses the actual timing of the deposition of the lev ratios obtained from oyster fragments and foraminifers from pre evaporitic units at odp site 654 tyrrhenian sea suggest that the major rifting phase in this region occurred between 8 and 6 5 ma ratios obtained from the early lev from the mediterranean sea suggest that initiation of evaporite deposition began about 5 65 ma ago results from units immediately overlying the uev in sicily suggest termination of evaporite deposition about 4 9 ma ago errors associated with these age estimates are about 0 5 ma 2

the mediterranean messinian salinity crisis an apennine foredeep perspective abstract owing to its expanded stratigraphic sections the apennine thrust belt offers the opportunity to better understand the evaporitic and post evaporitic messinian events a physical stratigraphic framework of messinian deposits based on facies analysis and basin wide correlation of key surfaces and sedimentary cycles is presented it is shown that the messinian apennine foredeep had marginal basins with shallow water primary evaporites and deeper basins where resedimented evaporites accumulated under relatively deep water conditions like many other mediterranean examples primary shallow water evaporites of apenninic marginal basins show evidence for subaerial exposure and erosion however the development of such an erosional surface does not correspond to the deposition of primary evaporites in the deepest part of the basin s here the unconformity can be traced towards the base of resedimented evaporites or to a level within them implying that the deeper basins of the apennine foredeep never underwent desiccation during the messinian salinity crisis but rather received the eroded marginal evaporites this fact usually overlooked raises important questions about the deep desiccation model of the mediterranean

revisiting the paleoproterozoic baraboo interval in southern wisconsin evidence for syn depositional tectonism along the south central margin of laurentia abstract the statherian baraboo quartzite 1710 1650 ma is present in the baraboo ranges wisconsin usa it is one of several isolated quartzites outcropping across the southern lake superior region collectively these quartzites are known as baraboo interval quartzites and they record a history of basin development followed by regional deformation along the south central laurentian margin baraboo interval stratigraphy above the baraboo quartzite in the baraboo ranges is unresolved limiting understanding of the style and history of basin formation sedimentation and deformation as well as correlation between regional quartzites new precambrian geologic mapping within the core of the baraboo syncline baraboo ranges wi confirms early interpretations of local stratigraphy the baraboo interval section includes two upward fining sequences separated by an angular unconformity the lower sequence comprises the baraboo quartzite seeley slate and freedom formation the upper sequence comprises the dake quartzite and rowley creek slate the depositional age of the upper sequence is poorly constrained but could be nearly 200 million years younger than the underlying units u pb detrital zircon ages for the lower conglomeratic baraboo quartzite and the dake quartzite are dominated by nearby basement ages between 1800 and 1750 ma and 1900 1835 ma suggesting a restricted drainage system tapping proximal basement sources subsidence modeling of the lower sequence demonstrates at least 1 28 km of subsidence is required to generate the accommodation necessary to deposit the baraboo quartzite seeley slate and freedom formation these results support a model where deposition of the lower sequence between ca 1710 1650 ma occurred along a tectonically active plate margin the lack of coeval magmatism in the baraboo interval suggests deposition did not occur in a convergent arc setting however coeval orthoquartzite deposition in colorado arizona and new mexico along the southwestern margin of laurentia 1700 1650 ma occurred synchronous with arc volcanism requiring a component of plate margin convergence to the southwest to reconcile these differences a model where the entire southern margin of laurentia between 1710 and 1650 ma was dominated by strike slip motion is favored varying from highly oblique convergence in the southwest to dominantly strike slip motion in the southern lake superior region

delineating mineralized phases based on lithogeochemical data using multifractal model in touzlar epithermal au ag cu deposit nw iran the aim of this study is to delineate and separate mineralization phases based on surface lithogeochemical au ag as and cu data using the concentration area c a fractal method in the touzlar epithermal au ag cu deposit nw iran four mineralization phases delineated by multifractal modeling for these elements are correlated with the findings of mineralization phases from geological studies the extreme phase of au mineralization is higher than 3 38 ppm which is correlated with the main sulfidation phase whereas ag extreme phase higher than 52 48 ppm is associated with silicic veins and veinlets the resulting multifractal modeling illustrates that au and ag have two different mineralization trends in this area extreme higher than 398 1 ppm and high mineralization phases of cu from the c a method correlate with hydrothermal breccias and main sulfidation stage in the deposit respectively different stages of au mineralization have relationships with as enrichment especially in high and extreme higher than 7 9 phases the obtained results were compared with fault distribution patterns showing a positive correlation between mineralization phases and the faults present in the deposit moreover mineralization phases of these elements demonstrate a good correlation with silicification and silicic veins and veinlets

lithofacies diagenetic spectra and sedimentary cycles of messinian late miocene evaporites in se spain abstract messinian evaporites have been deposited within a number of connected basins that formed the so called betic strait in se spain during the late miocene pre syn and postevaporitic sedimentary successions may well be compared with other strata of the same age surrounding the mediterranean sea there is no evidence for a cataract like connection of these basins with a strong unidirectional flow regime before and during the formation of messinian evaporites as previously suggested the most frequently occurring gypsum lithofacies presumably related to shallow water depositional environments are crystalline selenitic gypsum grass like gypsum laminated gypsum and cross bedded gypsarenite only few real sabkha type chicken wire alabastrine gypsum have been identified evenly laminated gypsum together with graded gypsarenites turbidites gypsrudites debrites and slumps is restricted to basins or parts of basins with considerable paleoslopes evidence for diagenetic overprinting is abundant in all outcrop areas studied this includes the formation of giant gypsum twin crystals super cones and alabastrine nodular gypsum the formation of messinian evaporites in se spain is thought to be controlled by a superimposed third order sea level lowstand smaller sedimentary units fall well into the range of fourth to sixth order cyclic and rhythmic successions they are clearly related to basin dynamics or to autogenetic processes of the local facies zone facies dynamics none of the smaller scale cycles fourth and higher order as observed in outcrops are related to high frequency eustasy

quantitative sequence stratigraphy sequence stratigraphy based on wire line logs cores and outcrops is entering its fourth decade of mainstream usage in industry and academia the technique has proved to be an invaluable tool for improving stratigraphic analyses in both clastic and carbonate settings here we present a simple quantitative technique to support sequence stratigraphic interpretations in clastic shallow marine systems the technique uses two pieces of data that are readily available from every subsurface field or outcrop study 1 parasequence thickness t and 2 parasequence sandstone fraction sf the key assumptions are that parasequence thickness can be used as a proxy for accommodation at the time of deposition and parasequence sandstone fraction can be used as a proxy for sediment supply this means that quantitative proxies for rates of accommodation development and sediment supply can be acquired from wire line logs cores and outcrop data vertical trends in parasequence thickness divided by sandstone fraction t sf approximate trends expected in systems tracts for changes in ratios of rate of accommodation development to rate of sediment supply the technique termed tsf analysis can also be applied at lower order sequence and composite sequence scales it provides a quantitative and objective methodology for determining rank and order of sequence stratigraphic surfaces and units absolute t sf values can be used to determine shoreline stacked shoreline and shelf margin trajectories four case studies are presented which demonstrate the robustness of the technique across a range of different data sets implications and potential future applications of tsf analyses are discussed

ecological control of sedimentary accommodation evolution from a carbonate ramp to rimmed shelf upper miocene balearic islands abstract stratal patterns and facies architecture develop in response to sediment flux and the available space for sediment accumulation accommodation in siliciclastic systems these two parameters are independent in carbonates however they are highly interdependent 1 sediment input production highly depends on biological systems and consequently on intrabasinal conditions nutrients temperature salinity etc 2 sediment dispersal depends on the production loci and on the interaction between the amount and type of sediment being produced and the hydraulic energy additionally biological processes binding baffling framework construction and even cementation frequently modify it 3 accommodation is not an independent factor with respect to sediment input type efficiency and area of the carbonate factory depend on sea level changes and sea floor morphology the base level for sediment to accumulate accommodation depends on the type and locus of sediment being produced the upper miocene carbonate platforms of the balearic islands illustrate how changes in intrabasinal environmental conditions nutrients and or temperature produce changes in stratal patterns and facies architecture if they affect the biological system during early tortonian carbonate production occurred both in the shallow euphotic zone foramol and in the deeper oligophotic zone rhodalgal originating a distally steepened ramp during late tortonian and early messinian carbonate production mainly occurred in the euphotic zone where framework producing biota coral reefs formed a rimmed platform although deposited under similar conditions of high frequency sea level fluctuations these two types of platforms exhibit different internal facies architecture and distribution of heterogeneities because of differences in base level in carbonates base level for sediment accumulation depends on the type and amount of sediment being produced on the production loci and on the processes controlling sediment dispersal base level for the loose foramol rhodalgal sediment associations of the ramp was controlled by wave and storm base and the associated currents whereas base level for the framework dominated reef complex was sea level furthermore the increase on effective accommodation space to allow the reef rimmed shelf to prograde onto the distally steepened ramp both platforms being depositional sequences resulted from an ecological change rather than significant relative sea level change namely by the shift from grain to framework producing biota the euphotic framework producing biota was able to fill the accommodation space existing between wave and storm base level and sea level that was not previously filled by the loose bioclasts

the onset of the messinian salinity crisis insights from cyprus sections abstract the neogene basins of southern cyprus provide a good opportunity to improve the knowledge of the paleoenvironmental changes involved in the triggering of the messinian evaporite deposition in the mediterranean and of their chronology which is still questionable with regards to the parameters responsible for the triggering of the salinity crisis it is still difficult to discriminate the individual effects of tectonics climate global sea level changes in cyprus considerable progress has been made on the events leading to the msc since the 70 s in high resolution microfossil biostratigraphy astrochronology cyclostratigraphy and magnetostratigraphy a study of the tochni section in the psematismemos basin correlated with previously studied sections in the western polemi and pissouri basins allows these regional paleoenvironmental changes to be correlated with the major events identified in other mediterranean basins the depth of the basins in which evaporites were deposited and the increase of salinity leading to the formation of evaporites are better constrained and studies confirm that restriction proceeded by steps throughout the mediterranean the very short time involved in the triggering of the onset of evaporite deposition in cyprus basins is marked by tectonic instability and development of very shallow water fauna and microbial communities indicating the water level lowered significantly just before the beginning of the massive gypsum precipitation correlation with other peri mediterranean basins where similar changes have been observed confirms that the period preceding the deposition of evaporites may correspond to the final closure of connections between the atlantic ocean and the mediterranean basin leading to a sea level drop and important hydrologic changes

parameterizing parasequences importance of shelf gradient shoreline trajectory sediment supply and autoretreat the basic reservoir flow unit in shallow marine depositional systems is the parasequence since it is bounded top and base by regionally extensive shales that can form barriers to fluid flow as a result it is the key stratigraphic unit requiring parameterization for both exploration and development purposes a database comprising 3385 measurement points from 385 parasequences from 28 locations and 16 different passive margin and foreland basins was compiled from outcrop and subsurface data analysis of the data suggests that a mean value for parasequence thickness is 17 m 56 ft mean parasequence sandstone fraction is 0 60 and mean shoreface sand body thickness is 8 m 26 ft the mean maximum parasequence progradation distance is 23 km 14 mi the results indicate that there are two critical controls that can significantly vary the parameter values stated above 1 stacked shoreline trajectory or systems tract and 2 shelf gradient the analyses indicate that shelf gradient is the most important parameter that has a first order control on parasequence properties shelf gradient in the ancient can be approximated to high gradient or low to moderate gradient categories via analysis of parasequence thickness change versus progradation distance from wells mean parasequence thickness or mean progradation distance from seismic attribute data parasequence progradation distance is to some degree predictable if stacked shoreline trajectory shelf gradient category and mean parasequence thickness are known the data suggest that there are two types of parasequences accommodation dominated and supply dominated parasequences the progradation distance of these parasequences are controlled by delta autoretreat mechanisms modulated by the combination of fifth and fourth order milankovitch scale orbitally forced climate change driven sediment supply cycles interacting with eustatically and tectonically driven accommodation cycles

marine to non marine sedimentation in the upper miocene evaporites of the eastern betics se spain sedimentological and geochemical evidence abstract several neogene basins in the eastern betics contain a record of thick upper miocene evaporites the inner basins those located distal to the mediterranean coast include evaporite units ranging from the late tortonian to the early messinian whereas the marginal basins those located in the vicinity of the mediterranean coast include evaporite units corresponding to the late messinian that are linked to the salinity crisis the sedimentological and geochemical comparison of the evaporites in the inner and marginal basins enable us to show their differences in the modes of deposition under local structural controls and differentiated palaeogeography in the inner basins of the murcia alicante region a number of evaporite units have been differentiated whose gypsum lithofacies have 1 variable strontium contents with mean values primary gypsum between 1121 and 2380 ppm 2 isotopic compositions of sulphur 34 s ranging from those characteristic of the tertiary marine water 20 3 to 25 5 to those characteristic of the triassic sulphates 8 0 to 16 0 the latter suggesting recycling of the sulphate anion in meteoric waters intermediate values 17 4 to 19 6 are attributed to mixed mother brines and 3 strontium ratios 87 sr 86 sr comprised between 0 70804 and 0 70888 these values range from those of the tertiary marine water to those exceeding the triassic sulphates suggesting additional continental contributions from country rocks and hydrothermal solutions the comparison between the sulphur and strontium isotopic compositions of the sulphates together with the study of the biota present in the marls associated with the gypsum allows us to distinguish between marine continental and mixed units in the marginal basins of the eastern betics where single evaporite units characterized by selenitic gypsum prevail 1 the strontium contents are more homogeneous with mean values primary gypsum between 493 and 625 ppm 2 the isotopic compositions of oxygen 18 o and sulphur 34 s are comprised between 12 2 and 14 8 and between 22 0 and 23 5 respectively and 3 the strontium ratios 87 sr 86 sr vary from 0 70890 to 0 70895 all these isotopic values reveal a marine origin and the lack of contribution of significant continental water during the late messinian evaporite deposition in the betic strait these characteristics are similar to those of the lower evaporite

on the geological significance of clastic parasequences abstract parasequences recognized in clastic sedimentary successions of shallow marine origin are considered by some geologists to be the fundamental building blocks of depositional sequences even though problems in their definition and application have been identified by others who instead advocate their abandonment as formal sequence stratigraphic units to elucidate the geological significance of clastic parasequences and inform the debate on their use in stratigraphy a quantitative characterization of the geometry facies characteristics and timescale of deposition of 1163 parasequences has been undertaken based on a synthesis of data from outcrop and subsurface studies that are available in the scientific literature through a database compilation the attributes of the studied parasequences are analysed with respect to the interpreted geological origin of the units and with consideration of sources of bias and uncertainty particular emphasis is placed on assessing the following i the importance of heuristics and of data types and coverage in the recognition of parasequences ii differences in parasequence characteristics observed across deltaic and shoreface depositional systems and between the quaternary and the ancient rock record iii possible explanations for the range in timescales of deposition of parasequences and iv the role of autogenic dynamics on the development of deltaic parasequences partly based on a comparison with the recent evolution of modern deltas the results demonstrate that parasequence definition and physical correlation suffer from subjectivity and that significant variability exists in the spatio temporal and architectural attributes of clastic parasequences this gives rise to uncertainty that affects the use of parasequences as a framework for comparison of the architecture of packages of strata originating via shoreline regression this uncertainty must be considered when using analogue data for subsurface predictions or when attempting comparative studies of clastic successions

how did the messinian salinity crisis end the cause of the desiccation of the mediterranean sea during the messinian salinity crisis has been widely debated but its re flooding remains poorly investigated interpretations generally involve tectonic collapse of the strait of gibraltar or global sea level rise or even a combination of both the dramatic sea level fall in the mediterranean has induced deep fluvial incision all around the desiccated basin we investigate erosion dynamics related to this base level drop by using the numerical simulator eros we show that intense regressive erosion develops inevitably in the gibraltar area eventually inducing the piracy of the atlantic waters by an eastward flowing stream and the subsequent re flooding of the mediterranean

timing of the last sequence boundary in a fluvial setting near the highstand shoreline insights from optical dating we investigated by means of optical dating the chronostratigraphic nature of the sequence boundary associated with the last glacial in a sandy to gravelly compound paleovalley fill just landward of the highstand shoreline in the rhine meuse delta netherlands laterally extensive fluvial strata deposited during oxygen isotope stage 4 coeval with a major sea level fall unconformably overlie estuarine deposits from stage 5 or fluvial deposits from the penultimate glacial stage 6 these chronostratigraphic relationships differ substantially from widely used models and indicate 1 that sequence boundary formation in this setting was associated with the onset of pronounced sea level fall shortly after 80 ka 2 that the time gap represented by the sequence boundary may be extremely small 10 k y 3 that the age of the sequence boundary may decrease both updip and downdip of the highstand shoreline and 4 that our study does not provide viable diagnostic criteria for a sea level controlled sequence boundary above the falling stage systems tract despite the high frequency high amplitude glacio eustatic regime that might be considered ideal for the formation of an unambiguous unconformity the last sequence boundary in this setting is commonly cryptic

accommodation succession δa δs sequence stratigraphy observational method utility and insights into sequence boundary formation the future of sequence stratigraphy depends on stratigraphers making observations with a common method so that physical frameworks can be clearly separated from interpretations of driving mechanisms depositional sequence boundary selection is a well known controversy that could be resolved with objective recognition criteria accommodation succession sequence stratigraphy refines traditional methods using sedimentary facies facies associations vertical stacking stratal geometries and stratal terminations as the objective record of competing rates of accommodation change and sediment fill through time observations are placed in context of lateral transgression and regression and vertical aggradation and degradation movement of shoreline through time across multiple timescales in hierarchal stacks the repeating motif consists of a subaerial unconformity and its correlative subaqueous surface overlain in coastal settings by a basinward shift in coastal onlap and strata with progradational to aggradation stacking then retrogradation and aggradation progradation degradation stacking these stacking patterns are bounded by key surfaces recognized by stratal terminations and characteristic vertical successions of facies this pattern is independent of time duration or position on a sea level curve but incorporates data resolution regional extent and hierarchal stacking examples from multiple datasets show the utility and objectivity of the method and provide insights into sequence boundary formation

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

sedimentology and paleoenvironmental evolution of messinian evaporites in the iskenderun hatay basin complex southern turkey abstract messinian evaporites which resulted from the salinity crisis during the final closure of the mediterranean sea are exposed in se turkey these evaporites formed in two isolated sub basins iskenderun arsuz ia and hatay samandag hs which belong to different depositional configurations and tectonic structures the neogene fill of these sub basins consists of a thick sedimentary succession that started with early miocene terrestrial clastics followed by reefs middle miocene and shallow water siliciclastics tortonian early to late miocene and finally messinian evaporates these sub basins accumulated in a diverse range of depositional environments from very shallow to deeper water evaporite facies in the ia sub basin consist of sabkhas saline lagoons and ponds they are mainly represented by chemical deposits such as scattered gypsum nodules and balls nodular bedded gypsum laminated gypsum type a and selenites type s1 evaporites in the hs sub basin mainly consist of detrital gypsum composed of gypsum laminae type b c gypsum arenite rudites and deeper water selenites 20 m and resedimented selenites type s2 which were deposited on a sulfate platform with a slope basin transitional zone secondary gypsum with alabastrine and porphyroblastic textures as well as satin spar veins is commonly associated with the sabkha type evaporites of the ia sub basin deeper water clastic evaporites of the hs sub basin have generally remained as primary gypsum or have only been slightly affected by diagenetic alterations the isotope values 87 86 sr 18 o smow and 34 s cdt from the different kinds of gypsum lithofacies of the sub basin are similar to those of the messinian evaporites in other peri mediterranean basins indicating an origin from marine water without external or basinal contributions the messinian evaporites examined in this paper are overlain by early pliocene zanclean deposits composed of shallow and deep water siliciclastics and carbonates with local intercalations of lago mare type strata throughout the messinian evaporitic stage the ia sub basin was mainly comprised of shallow water evaporites while the hs sub basin underwent deepening related to regional tectonics induced by the dead sea fault during the construction of the hatay graben

tectonic history of the hatay ophiolites south turkey and their relation with the dead sea rift abstract the kizildag ophiolite massif lies in the hatay region of s turkey some structural relationships in the area are examined and two geological sections through the ophiolite are presented a sequence of structural events dealing with the emplacement and post emplacement history is established the significance of the events is discussed and it is suggested that the post emplacement structural history was dominated by movements along the dead sea rift

critical differences in sediment delivery and partitioning between marine and lacustrine basins a comparison of marine and lacustrine aggradational to progradational clinothem pairs

geochemical variations within a laminated evaporite deposit evidence for brine composition during formation of the permian castile formation texas and new mexico usa abstract the upper permian castile formation of the delaware basin in northwest texas and new mexico consists of up to 600 m of evaporites and is subdivided into units of anhydrite overlain by halite the castile formation has commonly been interpreted as a deep water deep basin deposit in which sediments were laid down in several hundred metres of water or brine recent textural observations within anhydrite units in which the thick bedded anhydrite horizons have been interpreted as being of shallow water origin have challenged this assumption this geochemical study of the oldest anhydrite unit in the castile formation the anhydrite 1 member attempts to resolve some of the problems regarding brine depth and evolution in the basin the anhydrite 1 member has been subdivided into five major cycles on the basis of the distribution of stratigraphic units of thick bedded anhydrite stable isotopic analyses of sulphur from anhydrite and oxygen and carbon from calcite show that the basin waters were chemically homogeneous during precipitation of anhydrite and do not indicate any significant input of meteoric continental derived waters throughout the section studied progressive enrichment of 18 o upwards within cored intervals indicates continuous evaporation of the water body carbon isotopes appear to indicate fluctuations in organic activity within the cycles trace elemental analyses of fe mg sr mn al ba zn pb and cu from the sulphate fraction of the samples show a very high variability there is a distinct increase in trace elemental abundances at the tops of cycles which may indicate variations in precipitation kinetics analyses of texturally defined cycles show that up core trends for many of the trace elements correlate with changes in 18 o indicating a progressive increase in the influence of evaporation in addition cyclical variations in trace elemental composition indicate changes in basin conditions with around a 350 year cyclicity these changes are independent of 18 o values the geochemical data do not provide conclusive proof of water depth during deposition of the castile formation the data are interpreted as reflecting small scale changes in conditions of deposition despite the fact that water input remained essentially constant in terms of chemical composition

messinian climate change and erosional destruction of the central european alps at the end of the miocene the european alps ceased outward expansion and tectonic uplift and exhumation shifted into the orogen interior this shift is consistent with a change from orogenic construction to orogenic destruction reflecting an increase in the ratio of erosional flux to accretionary flux the coincidence of this change with an increase in sediment yield from the alps suggests a climate driven increase in erosional flux the timing of deformation and sediment release from the southern alps indicates that the tectonic change occurred synchronous with the last phase of the messinian salinity crisis we attribute the increase in erosional flux to a climatic shift to wetter conditions throughout europe likely augmented by the base level fall that occurred during the mediterranean dessication this climate change is represented in the stratigraphic record by the lago mare deposits of the mediterranean salinity crisis

evolution of late triassic rift basin evaporites passaic formation newark basin eastern north america the passaic formation of the late triassic newark supergroup is 2700 m thick and was deposited in series of wide deep to shallow lacustrine environments in the newark rift basin eastern north america the passaic formation can be divided into lower middle and upper sections based on depositional structures composition and the distribution and morphology of its evaporites evaporites formed as a result of syndiagenetic cementation and or displacive processes evaporitive minerals now include gypsum and anhydrite although other mineral species such as glauberite may have originally existed most of the evaporites of the passaic formation occur within massive red mudstone and siltstone lithologies in the form of diffuse cements void fillings euhedral crystals crystal clusters and nodules these evaporites grew displacively within the fine siliciclastic matrix as a result of changes in the hydrochemical regimes of the rift basin a well developed upward increase in the amount of evaporite material is present in the passaic formation this resulted from 1 long term progressive increase in aridity and 2 significant increase in evaporation surface area of the basin during its tectonic evolution a nonmarine source for the evaporites is evident from the isotopic data sulphate 34s ranges from 11 to 3 3 cdt while 18o ranges from 15 1 to 20 9 smow indicating derivation from early diagenetic oxidation of organic sulphur and pyrite within the organic rich lacustrine deposits the 87sr 86sr ratios in sulphate are radiogenic average 0 71211 showing the interaction of basin waters with detrital components and that the newark basin was isolated from the world ocean most of the original evaporites show evidence of diagenetic change to polycrystalline and polymineralic pseudomorphs now filled with recrystallized coarse grained anhydrite 1 3 mm size and low temperature albite homogenization temperatures of fluid inclusions within the coarse grained anhydrite indicate crystallization temperatures for anhydrite in the range of 150 to 280 c such elevated temperatures resulted from circulation of hot water in the basin later exhumation of these rocks caused partial to total replacement of anhydrite by gypsum in the upper part of the section the resulting increase in volume due to hydration of anhydrite at shallow depths also emplaced non evaporative satin spar veins fibrous gypsum along bedding planes and in fractures while the local geology of the newark rift basin controlled the distribution of facies the sedimentological development of the passaic formation evaporites resulted from the world wide climatic aridity that prevailed during the late triassic because the newark basin sequence was only covered with about 3 km of sedimentary overburden that correspond to about 100 c and hence suggests that evaporites have experienced alteration by hot fluids 5 as the triassic marks the greatest evaporite formation world wide and profound sense of parched continentality throughout the world existed before the final break up of the pangea the passaic formation evaporites are an example of the influence of these palaeoclimatic conditions at the eastern margin of north america

high resolution sequence stratigraphy and implications for cretaceous glacioeustasy of the late cretaceous gallup system new mexico u s a

mediterranean messinian salinity crisis constraints from a coeval marginal basin sorbas southeastern spain abstract the extent timing and effects of late miocene desiccation and evaporite deposition in the mediterranean sea remain controversial marginal basins containing messinian 5 3 7 1 ma sequences now exposed onland supplement information from the deep mediterranean but have evaporites of a variety of ages some of these messinian evaporites pre date and others post date deep desiccation none appears to be exactly coeval with those of the deep mediterranean in the betic cordillera of southern spain basins e g granada basin far from the present day mediterranean lost connection with the mediterranean due to uplift 1 ma before the salinity crisis and have marine evaporites of early not late messinian age in contrast basins such as the sorbas basin in southeastern spain adjacent to the present day mediterranean record events directly reflecting the course of the salinity crisis the sorbas basin retained marine connection with the western mediterranean up until evaporative drawdown in the mid messinian and was rapidly reflooded immediately afterwards the sorbas messinian sequence is up to 320 m thick it is complete and normal marine except for an incised basinwide erosion surface overlain by a 130 m thick gypsum deposit we propose that this surface marks the interval of deep desiccation of the adjacent mediterranean basin erosion occurred shortly after 5 9 ma and the irregular unconformity has relief of at least 240 m confirming mediterranean drawdown significantly below the atlantic level sorbas gypsum deposits overlie the unconformity and are intercalated with marls estimated at 5 5 ma containing normal marine messinian biotas these gypsum deposits therefore post date deep desiccation and formed in a silled basin immediately following marine reflooding they mark the end of the salinity crisis and are overlain by 70 m of normal marine sediments containing unreworked foraminifers of latest messinian age this succession demonstrates that the salinity crisis occurred faster and was completed sooner than previously believed it took place within 0 4 ma time scale of berggren et al 1995b is 0 2 ma on the time scale of baksi 1993 and was completed before the end of the messinian this corrects previous views that the salinity crisis continued until the early pliocene there is no evidence in the sorbas basin for brackish lago mare conditions and the normal marine biotas that directly precede and follow drawdown rebut earlier suggestions of prolonged salinity effects

deep water clastic evaporites deposition in the messinian adriatic foredeep northern apennines italy did the mediterranean ever dry out a new genetic facies model for deep water clastic evaporites is presented based on work carried out on the messinian gessoso solfifera formation of the northern apennines during the last 15 years this model is derived from the most recent siliciclastic turbidite models and describes the downcurrent transformations of a parent flow mainly composed of gypsum clasts the model allows clearer comprehension of processes controlling the production and deposition of clastic evaporites representing the most common evaporite facies of the northern apennines and the definition of the genetic and stratigraphic relationship with primary shallow water evaporites formed and preserved in marginal settings due to the severe recrystallization processes usually affecting these deposits petrographic and geochemical analyses are needed for a more accurate interpretation of the large spectrum of recognized gravity driven deposits ranging from debrisflow to low density turbidites almost all the laminar balatino gypsum previously considered a deep water primary deposit is here reinterpreted as the fine grained product of high to low density gravity flows facies associations permit the framing of the distribution of clastic evaporites into the complex tectonically controlled depositional settings of the apennine foredeep basin the messinian salinity crisis occurred during an intense phase of geodynamic reorganization of the mediterranean area that also produced the fragmentation of the former miocene apennine foredeep basin in this area primary shallow water evaporites equivalent to the mediterranean lower evaporites apparently only formed in semi closed thrust top basins like the vena del gesso basin the subsequent uplift and subaerial exposure of such basins ended the evaporite precipitation and promoted a widespread phase of collapse leading to the resedimentation of the evaporites into deeper basins vertical facies sequences of clastic evaporites can be interpreted in terms of the complex interplay between the messinian tectonic evolution of the apennine thrust belt and related exhumation erosional processes the facies model here proposed could be helpful also for better comprehension of other different depositional and geodynamic contexts the importance of clastic evaporites deposits has been overlooked in the study of other mediterranean areas based on the apennine basins experience it is suggested here that evaporites diffused into the deeper portions of the mediterranean basin may consist mainly of deep water resedimented deposits rather than shallow water to supratidal primary evaporites indicative of a complete basin desiccation