quaternary deformation and uplift of coral reef terraces produced by oblique subduction and underthrusting of the bahama platform below the northern hispaniola forearc abstract active tectonics linked to the rise of the hispaniola forearc explain the morphological characteristics spatial distribution and u th geochronological ages of the uplifted coral reef terraces of the la isabela formation in both the eastern cordillera septentrional and the samana peninsula of northeastern dominican republic depositional coral reef terraces of mis 5e tii 7e tiii and 9 tiv stages occur respectively at maximum heights of about 25 m 80 m and 120 m above the current sea level the development of heterogeneous brittle deformation structures in the coral limestone at all scales document active tectonics and include small faults shear fractures extensional joints and calcite veins their geometric and kinematic characteristics as well as the stress tensors calculated from fault slip and fracture orientation data are all compatible with ene to ne trending regional shortening and indicate that a left lateral transpressive regime is deforming the forearc during the quaternary along the northern hispaniola coastline the tectonic uplift mimics the distribution of the bathymetric features on the subducting bahamas platform outboard the hispaniola puerto rico trench the highest calculated uplift rates in the eastern cordillera septentrional and samana peninsula correspond to the collision zone of the silver spur and navidad bank 0 4 m ka respectively uplift rates decrease towards the west 0 2 m ka where the oblique collision of carbonate ridges and related forearc deformation would not have been recorded since at least the early pleistocene oblique subduction and underthrusting of the bahamas platform followed by basal erosion at the subduction channel explain the observed time transgressive pattern of uplift and subsidence in the northern hispaniola forearc and the change from accretionary to erosive processes in the convergent margin

foraminifera in elevated bermudian caves provide further evidence for 21 m eustatic sea level during marine isotope stage 11 abstract two hypotheses have been proposed to explain the origin of marine isotope stage mis 11 deposits in small bermudian caves at 21 m above modern sea level 1 a 21 m mis 11 eustatic sea level highstand and 2 a mis 11 mega tsunami event importantly the foraminifera reported in these caves have yet to be critically evaluated within a framework of coastal cave environments after statistically comparing foraminifera in modern bermudian littoral caves and the mis 11 calonectris pocket a 21 m cave to the largest available database of bermudian coastal foraminifera the assemblages found in modern littoral caves and calonectris pocket a cannot be statistically differentiated from lagoons this observation is expected considering littoral caves are simply sheltered extensions of a lagoon environment in the littoral zone where typical coastal processes waves storms homogenize and rework lagoonal reefal and occasional planktic taxa fossil protoconchs of the bermudian cave stygobite caecum caverna were also associated with the foraminifera these results indicate that the mis 11 bermudian caves are fossil littoral caves breached flank margin caves where the total mis 11 microfossil assemblage is preserving a signature of coeval sea level at 21 m brackish foraminifera polysaccammina pseudothurammina and anchialine gastropods 95 300 individuals indicate a brackish anchialine habitat developed in the elevated caves after the prolonged littoral environmental phase the onset of sea level regression following the 21 m highstand would first lower the ancient brackish ghyben herzberg lens

quaternary reef response to sea level and environmental change in the western atlantic the tropical subtropical western atlantic realm harbours abundant fringing reefs two major barrier reefs belize florida several atolls and large reef fringed carbonate platforms bahamas data from belize and south florida indicate that major barrier reefs were established during the high sea levels of the long and warm marine isotope stage 11 reefs formed during pleistocene sea level highstands whereas erosion non deposition and the formation of subaerial exposure surfaces prevailed during lowstands of sea level florida bahamas exposed reefs and platforms with siliciclastic hinterlands were characterized by deposition of clays and sands on fluvial plains belize elevated terraces and outcrops of reefs of the last interglacial of marine isotope stage 5e are evidence of higher than present sea level and temperature that sustained large reef fringed carbonate platforms and ramps in the florida bahamas region and central america belize mexico including ooid deposition in warm and shallow waters during the highstands of marine isotope stages 5c and 5a at sea levels several metres lower than today fringing reefs developed in parts of the caribbean for example in south florida outlier reefs data from the island of barbados support the contention that the postglacial sea level rise from about 120 m was rapid and punctuated by two meltwater pulses ia and ib which bracket the beginning and end of the younger dryas respectively after reflooding of shelves in the early holocene reefs developed preferentially on highs of the underlying karstified pleistocene limestone surface and on former river channel bars many reefs in the western atlantic region kept pace with holocene sea level rise whereas some were drowned reasons for reef drowning are debated and include sea level rise elevation of antecedent topography and deterioration of environmental conditions such as high nutrient input apart from sea level and antecedent topography factors such as exposure to waves and currents storms and sedimentation have controlled reef development the historical decline of acroporid corals in the caribbean realm has been attributed to cooling following the holocene thermal optimum however historical die offs of reef building corals and other reef organisms suggest that some if not all recent declines were unprecedented during the holocene rising temperatures decreasing carbonate saturation increased frequency of major storms high nutrient concentrations and sedimentation overfishing and disease certainly played a role in decline but systematic studies relating these environmental factors to holocene reef building are only in the early stages

tectonics and magmatism in turkey and the surrounding area this volume contains 23 papers from a range of international contributors describing recent research into the tectonics and magmatism of turkey and its surroundings this region is sited at the collision zone between eurasia and afro arabia and as such provides an extraordinarily complete and well exposed record of the staged tectonic evolution of this sector of the alpine himalayan orogen the geological history of this area involves separation of continental fragments from the margin of gondwana their migration across the tethyan oceans the subsequent closure of these oceans and finally the development of the neotectonic regime which continues to evolve to the present day such a comprehensive record is relevant to the understanding of collisional zones worldwide the volume is divided into five sections tethyan evolution neotethyan ophiolites post tethyan basin evolution neotectonics and igneous activity the first two sections deal with tethyan oceans whose growth and subsequent closure dominated the geodynamic framework in the mesozoic and cenozoic the subsequent sections deal with more recent geological developments from the balkan peninsula in the west to the transcaucasus in the east that followed consumption of the tethyan oceans there is a broad mix of papers throughout the volume wide ranging review papers on ocean development and extensional tectonics are followed by detailed descriptions of petrology and geochemistry and geographically focused studies on basin evolution specific aspects of extensional and strike slip tectonics and discussions of the relationship of magmatic activity to the tectonic development of the area tectonics and magmatism in turkey and the surrounding area presents up to date results and ideas from a large number of international contributors on a wide range of current research activity in this region it is essential reading for all geoscientists with an interest in both academic and applied aspects of eastern mediterranean geology

collapse of polar ice sheets during the stage 11 interglacial the magnitude of sea level rise during marine isotope stage 11 about 400 000 years ago is shown to have been probably only 6 to 13 metres in contrast to some earlier estimates of up to 20 metres the ice sheets in greenland and west antarctica are known to be susceptible to climate warming and both are losing mass how the east antarctic ice sheet will respond to warming is less clear recent evidence from shoreline features in bermuda and the bahamas suggested that during marine isotope stage 11 a period of warming that occurred about 400 000 years ago the sea level was 20 metres higher than it is today which pointed to significant melting of the east antarctic ice sheet now an estimate that takes into account post glacial crustal subsidence of the shoreline sites during an anomalously long interglacial period puts the sea level during stage 11 at 6 13 metres higher than today that can be explained by the collapse of the greenland and west antarctic ice sheets with only a small contribution from the east antarctic ice sheet contentious observations of pleistocene shoreline features on the tectonically stable islands of bermuda and the bahamas have suggested that sea level about 400 000 years ago was more than 20 metres higher than it is today1 2 3 4 geochronologic and geomorphic evidence indicates that these features formed during interglacial marine isotope stage mis 11 an unusually long interval of warmth during the ice age1 2 3 4 previous work has advanced two divergent hypotheses for these shoreline features first significant melting of the east antarctic ice sheet in addition to the collapse of the west antarctic ice sheet and the greenland ice sheet1 2 3 or second emplacement by a mega tsunami during mis 11 ref 4 5 here we show that the elevations of these features are corrected downwards by 10 metres when we account for post glacial crustal subsidence of these sites over the course of the anomalously long interglacial on the basis of this correction we estimate that eustatic sea level rose to 6 13 m above the present day value in the second half of mis 11 this suggests that both the greenland ice sheet and the west antarctic ice sheet collapsed during the protracted warm period while changes in the volume of the east antarctic ice sheet were relatively minor thereby resolving the long standing controversy over the stability of the east antarctic ice sheet during mis 11

mixed carbonates and siliciclastics in the quaternary of southern belize pleistocene turning points in reef development controlled by sea level change the belize barrier and atoll reefs represent one of the largest reef structures in the atlantic ocean the southern shelf of belize is a classic location of a modern mixed carbonate siliciclastic system whereas knowledge of the holocene deposits in the area is extensive data on the pleistocene system are fragmentary open questions include i the nature of the reef foundations carbonate versus siliciclastics ii the ages of the deposits including the initiation of the barrier reef and iii the response of the mixed system to sealevel fluctuations the results of a study of borings on the southern belize shelf are presented here six up to 105 m long borings were made to better understand the history of this important mixed system uranium series dating in the pleistocene was not possible because of diagenetic alteration however lithostratigraphy strontium isotopes and calcareous nannofossil biostratigraphy were used to constrain stratigraphic ages results support the contention that the quaternary development in belize was quite similar to that of other major barrier reefs such as the florida reef tract and further afield the great barrier and the new caledonian barrier reefs all of these barrier reefs are mixed carbonate siliciclastic systems and significant reef growth only began after the onset of high amplitude eccentricity controlled sea level changes and as late as during the exceptionally long and warm marine isotope stage 11 some 400 ka in belize early pleistocene sections at bases of borings include mollusc rich wackestones rare coral packstones and marls which were deposited under low to moderate energy conditions in a ramp setting before ca 900 ka during the high sea levels of marine isotope stage 25 and possibly earlier marine isotope stage 31 or 37 the belize shelf was subaerially exposed for most of the mid pleistocene and was dominated by siliciclastic sedimentation possibly during marine isotope stages 24 to 12 when highstands were comparatively low continuous reefs at the shelf margin were developing during highstands in the late pleistocene beginning with the long and high highstand of marine isotope stage 11 some 400 ka the southern shelf was flooded entirely and carbonates started to dominate once more reefs developed on top of siliciclastic deposits on the shelf a continuous barrier reef came into existence and largely developed on top of carbonates at the shelf margin during late pleistocene lowstands siliciclastics presumably no longer reached the shelf margin because of the topographic high of the barrier reef platform the quaternary belize example may serve as a model for reconstructing ancient mixed systems in icehouse worlds however any extrapolations are limited by the fact that fast growing scleractinian reef builders had not yet evolved in the palaeozoic

actively evolving microplate formation by oblique collision and sideways motion along strike slip faults an example from the northeastern caribbean plate margin abstract the pattern of folding faulting and late quaternary coral reef uplift rates in western and central hispaniola haiti and dominican republic suggest that the elongate gonave microplate a 190 000 km2 area of the northeastern caribbean plate is in the process of shearing off the caribbean plate and accreting to the north american plate late cenozoic transpression between the southeastern bahama platform and the caribbean plate in hispaniola has inhibited the eastward motion of the northeastern corner of the plate transpression is manifested in western and central hispaniola by the formation of regional scale folds that correspond to present day anticlinal topographic mountain chains continuous with offshore anticlinal ridges areas of most rapid quaternary uplift determined from onland coral reefs 125 ka and younger coincide with the axial traces of these folds offshore data suggest recent folding and faulting of the seafloor onshore reef data do not conclusively require late quaternary folding but demonstrate that tectonic uplift rates of the axial areas of the anticlines decrease from the northwest peninsula of haiti 0 37 mm yr to to the central part of the coast of western haiti 0 19 mm yr to the south central part of western haiti 0 mm yr formation of the 1200 km long enriquillo plantain garden walton fault zone as a bypass strike slip fault has isolated the southern edge of the gonave microplate and is allowing continued unimpeded eastward motion of a smaller caribbean plate past the zone of late neogene convergence and quaternary uplift of coral reefs in hispaniola offshore seismic reflection data from the jamaica passage the marine strait separating jamaica and haiti show that the enriquillo plantain garden fault zone forms a narrow but deep active fault bounded trough beneath the passage the active fault is continuous with active faults mapped onshore in western haiti and eastern jamaica the bathymetric deep is present because the jamaica passage fault segment represents a 50 km wide transtensional left step of the fault trace between haiti and jamaica onshore satellite imagery and field observations suggest that the enriquillo plantain garden fault forms a continuous trace extending from central hispaniola east of lake enriquillo dominican republic to the westernmost end of the southern peninsula of haiti the regional lineament corresponds to a recent fault scarp in quaternary alluvium of the clonard pull apart basin in the central part of the southern peninsula of haiti and suggests that at least this part of the lineament has undergone recent slip calmus 1983 has suggested a total offset of 30 50 km of the enriquillo plantain garden fault zone in the southern peninsula of haiti using the apparent offset of lithologic units seismic reflection data from lake enriquillo document recent deformation of quaternary lake sediments where the lineament crosses the lake leveling of the crest of a late holocene coral reef and associated algal tufa around lake enriquillo demonstrate late holocene vertical movement and tilting in a 1500 m wide zone parallel to the fault trend lateral offset is difficult to show in the enriquillo valley area because of rapid recent sedimentation into the valley the pattern of inactive strike slip faults and fold belts of cenozoic age in cuba and the yucatan basin suggest that two elongate microplates were sheared off the proto caribbean plate and accreted to the north american plate by a similar process in paleocene and eocene times age of terminal deformation in western central and eastern cuba is consistent with southeastward younging and migration of arc collision the similarity of the size and sequence of events in cuba suggests that the process of oblique collision and sideways motion of the plate along a new strike slip fault towards a free face may be an important process of microplate formation and interplate transfer in other areas

a satellite image approach to the study of lineaments circular structures and regional geology in the golcuk crater district and its environs isparta sw turkey abstract important volcanic occurrences such as a sub volcanic stock caldera volcano cones circular semicircular and elliptical morphologic structures have been identified in the golcuk crater lake district and surrounding area sw turkey our satellite image analysis shows that the volcanic activity occurred during different volcanic phases maps of lineaments and geology of the region were prepared using colors drainage patterns textural features vegetation cover and morphological forms as interpretation parameters in addition the major fracture directions of the region were detected from lineament analysis as trending ne n and nw the relationship of pliocene golcuk volcanism with tectonism was defined and these data are interpreted the satellite image reveals that the volcanic structures and the golcuk crater generally occur at the intersections of different lineaments where the number of lineaments increases lineament analysis on landsat satellite images is a useful tool for detecting volcanic regions alteration and mineralization zones

an open system model for u series age determinations of fossil corals the source of excess 234u in fossil corals and its relationship to u series age determinations has been an outstanding problem in geochronology for more than 20 years with increasing numbers of u series isotope measurements in corals and significant improvements in analytical precision through mass spectrometry it is increasingly apparent that a substantial fraction of observed isotope ratios cannot be reasonably explained by closed system decay moreover observations of a positive correlation between 234u 238u and 230th 238u ratios in corals from the same terrace are difficult to explain however the decay of dissolved uranium and recoil mobilization of uranium daughters produce particle reactive 234th and 230th and the coupled addition of these th isotopes could simultaneously increase coral 234u 238u and 230th 238u here we present a quantitative model based on decay dependent redistribution of 234th and 230th permitting calculation of open system coral ages these equations provide a general solution to the recoil redistribution problem applicable to any alpha decay series while measured isotope ratios of corals from the three youngest stratigraphically defined barbados terraces are inconsistent with closed system decay they fall in broadly linear arrays agreeing with model predictions isotopic arrays of older barbados corals and corals from terraces around the world are also consistent with model predictions suggesting the open system model is generally applicable corals with extreme isotopic compositions that are impossible to produce by closed system decay are consistent with the limited range of isotopic compositions predicted by the model at ages older than 600 ka for corals from a single terrace 234th and 230th redistribution appears to be a source of systematic conventional age error even for corals with slightly elevated 234u however open system ages are consistent even for corals with extremely elevated 234u for the youngest three barbados terraces mean open system terrace ages are consistent with mean conventional terrace ages calculated from pristine samples if the most accurate conventional ages are from corals with an initial 234u 238u identical to modern seawater then the open system model will improve the accuracy of coral u series age determinations and dramatically increase the number of reliable ages

pliocene lower pleistocene shallow water mixed siliciclastics and carbonates yanigua and los haitises formations in eastern hispaniola dominican republic the virtually unfolded sedimentary cover of the cordilleras central and oriental in the eastern dominican republic eastern hispaniola tropical north atlantic largely consists of pliocene to early pleistocene mixed siliciclastics and carbonates these deposits have been grouped into two laterally interfingering mapping units the yanigua and los haitises formations the former mainly siliciclastics comprises marl marly limestone and minor conglomerate sandstone lignite and carbonaceous clay and crops out closest to the basement the los haitises formation mainly consists of limestone and intercalating beds of marly limestone and marl lithological mapping at the 1 50 000 scale and facies analysis of twelve measured sections and of additional fourteen outcrops suggest that these deposits mainly formed on a shallow water marine platform fringing the precursor reliefs of the cordillera oriental and the southeastern end of the cordillera central only a limited proportion of sediment formed in floodplains and marshes marl and marly limestone dominated the inner platform sediments terrigenous mud decreased away from the emergent basement and carbonate sedimentation dominated the more external platform corals molluscs echinoids foraminifers bryozoans coralline algae and halimeda are the main components with varying amounts of carbonate mud the platform was generally a low energy environment with seagrass patches in the inner platform corals grew as isolated colonies or as small patch reefs dominated by porites in marly and bioclastic substrates branching corals stylophora and acropora grew in extensive carpets in more distal areas at least in the last stage of its development early pleistocene the platform was rimmed by a reef barrier similar to the holocene caribbean barrier reefs with acropora gr palmata a cervicornis porites montastrea siderastrea and diploria as the main reef builders

seamarc ii mapping of transform faults in the cayman trough caribbean sea seamarc ii maps of the southern wall of the cayman trough between honduras and jamaica show zones of continuous well defined fault lineaments adjacent and parallel to the wall both to the east and west of the cayman spreading axis these lineaments mark the present active traces of transform faults which intersect the southern end of the spreading axis at a triple junction the swan islands transform fault to the west is dominated by two major lineaments that overlap with right stepping sense across a large push up ridge beneath the swan islands the fault zone to the east of the axis named the walton fault is more complex containing multiple fault strands and a large pull apart structure the walton fault links the spreading axis to jamaican and hispaniolan strike slip faults and it defines the southern boundary of a microplate composed of the eastern cayman trough and western hispaniola the presence of this microplate raises questions about the veracity of caribbean plate velocities based primarily on cayman trough opening rates

muertos trough subduction microplate tectonics in the northern caribbean the relative plate motion between the north american and caribbean plates has been commonly assumed to take place in the form of oblique subduction along the puerto rico trench1 west of hispaniola this plate boundary becomes pure strike slip nevertheless it has been suggested that this boundary is more diffuse with part of the plate motion taken up by subduction along the muertos trough mt south of hispaniola2 5 fig 1 but there has been no direct seismological evidence of subduction to confirm this here we present the results of a study of the 24 june 1984 earthquake beneath mt the focal mechanism shows thrusting at a depth of 32 km which together with reports of a great earthquake in 1751 confirms that mt is an active plate boundary this implies that plate motion is accommodated by several tectonic boundaries delineating microplates caught between the caribbean and north american plates fig 4

petrology and geochemistry of potassic rocks in the golcuk area isparta sw turkey genesis of enriched alkaline magmas abstract the lower pliocene volcanic rocks occurring in the golcuk area of sw turkey exhibit alkaline major element trends with a general potassic character the development of volcanism can be divided into 2 major stages such as trachytic ancient lavas domes and tephriphonolitic trachyandesitic to trachytic golcuk eruptions ignimbrites lava dome extrusions phreatomagmatic deposits and finally young domes volcanic rocks consist primarily of plagioclase clinopyroxene which ranges in composition from diopside to augite and are commonly zoned biotite and phlogopite amphibole phenocrysts are restricted to the pyroclastic deposits pseudoleucites are also seen only in the lava dome extrusions oxides and apatites are common accessory phenocryst phases as would be expected from their potassic alkaline nature the volcanic rocks of the golcuk area contain high amounts of lile ba sr rb and k lree and zr concentrations of compatible elements such as cr ni and v are very low possibly indicating fractionation of olivine and clinopyroxene correlation of sio2 rb sr and mgo with 87 sr 86 sr 0 703506 0 704142 exhibit an increasing trend in the direction of crustal contamination however the isotopic compositions of sr are not as high to indicate a high level of crustal contamination geochemical data are consistent with the derivation of golcuk volcanic rocks from a metasomatized and or enriched lithospheric mantle source during crustal extension in the area this metasomatism was probably occurred by fluids released from the northward subduction between african and eurasian plates during tertiary as the golcuk volcanic rocks display features of island arc magmas with having high ba nb 28 ratios and nb and ti depletions lower pliocene volcanism in the golcuk was response to extensional tectonics

dense brine refluxing a new genetic interpretation of widespread anhydrite lumps in the oligocene lower miocene asmari formation of the zagros foreland basin ne iraq abstract the asmari formation in the zagros basin of ne iraq contains a thick sequence of oligocene lower miocene carbonates and it forms one of the best known carbonate reservoirs in the world the formation mainly consists of dolostones limestones sandstones and mudstones and there is a general upward increase in the abundance of evaporites generally in the form of anhydrite lumps in the dolostones of the upper part the anhydrite types and textures provide evidence on the salinity depth temperature environment and sea level fluctuations which can be used for paleoenvironmental and climatic interpretations and they also exert a significant control on reservoir quality which has attracted the attention of many petroleum industries previous studies suggested that the anhydrite lumps in the upper asmari formation aquitanian burdigalian were synsedimentary deposits in a hypersaline setting of a sabkha salt flat however this paper shows that 1 the upper asmari formation was deposited in an inner to mid ramp setting based on the sedimentological petrographical and paleontological characteristics 2 the anhydrite lumps are irregular and variable in size and are generally found within or associated with karst systems and 3 fossil assemblages indicate that the synsedimentary salinity was normal or only slightly hypersaline which means that the anhydrite was not directly deposited from the synsedimentary marine water after comprehensive analysis of the anhydrite lumps it is proposed in this paper that the anhydrite lumps were formed within the upper asmari formation aquitanian burdigalian due to downwards seepage of the overlying hypersaline water which is termed as dense brine refluxing a new genetic model it is suggested 1 that the upper asmari formation aquitanian burdigalian was deposited in an inner to mid ramp setting and subjected to eogenetic karstification generating karst systems in local area with relative high landscape due to sea level change 2 that during the middle miocene tectonic compression resulted in the zagros basin isolated and the seawater becoming hypersaline with higher salt concentrations and a high density and 3 the hypersaline water seeped downwards through the underlying porous sediments forming anhydrite lumps and resulting in a decrease in the porosity of the upper asmari formation aquitanian burdigalian this paper provides new perspectives on the origin of anhydrite lumps and the resulting effects on reservoir quality in the zagros foreland basin

late pliocene to holocene platform evolution in northern belize and comparison with coeval deposits in southern belize and the bahamas the full text is not available on soar access this article via the commercial databases licensed by university libraries http libcat wichita edu vwebv holdingsinfo searchid 817 reccount 30 recpointer 1 bibid 1334578

a revised morpho and chronostratigraphy of the late and middle pleistocene coral reef terraces on southern barbados west indies the barbados coral reef terraces are one of the few type localities worldwide that provide insights into interglacial sea level change during the late and middle pleistocene several sea level estimates have been established since the late 1960s and each has contributed to the barbados model of sea level change this paper presents new morpho and chonostratigraphic data from the barbados coral reef terraces developed over the last 12 years the work is based on significant advances in electron spin resonance esr dating of fossil coral air photo interpretation and a greatly improved geomorphic map of preserved fossil beach formations and reef terraces above present sea level the need for a revision of past published morpho and chronostratigraphies is best demonstrated on the southern part of the island the morpho and chronostratigraphic sequence in this region is both more complex and diverse than has been assumed so far the revised morphostratigraphy presented here includes a differentiation of coral reef terraces wave cut platforms and other erosive features such as notches and cliffs our study of these geomorphic features combined with new numeric dating results esr u th enable a revised estimate of the spatial and temporal variation in tectonic uplift rate within south barbados these new rates are an essential requirement for more precise glacio eustatic sea level reconstructions during the late and middle pleistocene from this region

petrology and geochemistry of augite trachytes and porphyritic trachytes from the golcuk volcanic region isparta sw turkey a case study abstract the plio quaternary alkaline volcanic rocks at golcuk isparta sw turkey include older porphyritic trachytes augite trachytes and younger trachyandesitic and tephriphonolitic dikes in order to better understand their pre eruptive evolution the geochemical variations of porphyritic trachytes and augite trachytes have been modeled quantitatively using the melts algorithm ghiorso and sack 1995 their geochemical variations are also compared with those of the younger series results show that two distinct magma series trachyte trachyandesite and tephriphonolite governed the petrogenesis of golcuk volcanic rocks geochemistry of the trachytic trachyandesitic series is controlled predominantly by clinopyroxene and plagioclase fractionation at a shallow depth under oxygen fugacity conditions two units above the qfm buffer melts calculations also show that the crystallisation of trachytic trachyandesitic magma produces clinopyroxene plagioclase alkali feldspar biotite apatite and magnetite quartz consistent with the mineralogy of the augite trachyte porphyritic trachyte and trachyandesitic dikes

neotectonic intersection of the aegean and cyprus tectonic arcs extensional and strike slip faulting in the isparta angle sw turkey abstract the isparta angle and adjacent antalya bay areas constitute an important segment of the eastern mediterranean region located at the intersection of the southward convex aegean and cyprus arcs some recent tectonic maps show the isparta angle as a nw se compressional lineament extending eastwards into the kyrenia range of northern cyprus however fault data from the onshore isparta angle together with offshore shallow seismic reflection data show that the present morpho tectonic setting is dominated by extension the last phase of compression to affect the area studied in the late miocene was accompanied by regional nappe emplacement lycian nappes onshore fault planes measured from fault zones bounding both the limbs and the core of the isparta angle are oriented predominantly ne sw nw se and n s superimposed slickenfibres show that reverse faults were succeeded in turn by right lateral faults then by normal faults the fault phases are dated by stratigraphical and geomorphological evidence reverse faults date from the late miocene or earlier compressional deformation whereas the right lateral faults mainly developed during latest miocene early pliocene normal faulting dominated from the late pliocene recent an interpretation of shallow seismic reflection data shows that antalya bay is characterised by a nw se trending asymmetrical graben system that has continued to be active during the late miocene early pliocene right lateral strike slip resulted from shear along the eastern termination of a zone of extension and rotation that characterises the western aegean this shear was focused in a n s direction by inherited zones of structural weakness in the basement antalya complex the switch to ne sw extension in the late pliocene quaternary relates to a regional change in stress direction throughout the aegean region and was accompanied by strong uplift of the bey da lari region of the taurus mountains bordering the isparta angle in the west the isparta angle is the link between a the extensional province of western turkey bounded to the south by the actively subducting hellenic arc and b the uplifted anatolian plateau bounded to the south by the cyprus subduction zone understanding the miocene to recent tectonic development helps elucidate the kinematics of the region the new structural data presented lend no support for recent suggestions that the isparta angle and antalya bay represent parts of a regional compressional zone related to plate collision

plio pleistocene palaeogeography of the llanura costera del caribe in eastern hispaniola dominican republic interplay of geomorphic evolution and sedimentation this paper aims to reconstruct the palaeogeographic evolution of the llanura costera del caribe lcc in eastern hispaniola dominican republic during the pleistocene adding new insights to published information on pliocene early pleistocene deposits the lcc is a generally flat region comprising the unfolded sedimentary cover of the cordilleras central and oriental within this cover the pliocene early pleistocene yanigua formation mainly consisting of marl changes seawards to the mainly limestone los haitises formation both units formed in a shallow water platform rimmed by a reef barrier at least in the latest depositional stages the overlying pleistocene la isabela formation consists of two major offlapping reef terraces in which a reef core enclosed a lagoon and prograded over forereef bioclastic debris two belts in lcc s morphostructure directly reflect its sedimentary evolution the inner belt extends over the marly substrate of the yanigua formation and the coastal belt comprises three major surfaces corresponding to the depositional top of the los haitises formation upper surface and to the upper and lower terraces of the la isabela formation intermediate and lower surfaces respectively the mis 5e age of the 10 20 m high lower terrace implies a low uplift rate of 0 033 0 068 mm yr for the lower surface the pliocene early pleistocene platform was emergent in the early middle pleistocene the early pleistocene reef barrier separated endorheic watersheds extending over the former shelf lagoon from the open ocean reefs built the upper terrace of the la isabela formation during one or several middle pleistocene highstands and the lower terrace during mis 5e and previous highstands siliciclastic deposits in this terrace record the opening to the caribbean sea of watersheds in the eastern lcc the lower terrace emersion and opening of the large drainage systems of the western and central lcc took place after mis 5e relative sea level fall and emersion of a large area did not imply increased terrigenous sedimentation in the adjacent marine basin development of endorheic watersheds over most of the emergent surface delayed the diachronic arrival of siliciclastics into the marine basin for hundreds of thousands of years

a sustained 21 m sea level highstand during mis 11 400 ka direct fossil and sedimentary evidence from bermuda abstract a small protected karstic feature exposed in a limestone quarry in bermuda preserved abundant sedimentary and biogenic materials documenting a transgressive phase still stand and regressive phase of a sea level in excess of 21 3 m above present during marine isotope stage mis 11 400 ka as determined by u th dating and amino acid racemization cobbles and marine sediments deposited during the high energy transgressive phase exhibit rim cements indicating a subsequent phreatic environment this was succeeded stratigraphically by a still stand deposition of fine calcareous lagoonal sediments containing bioclasts of red algae and benthic and planktonic foraminifera that was intensely burrowed by marine invertebrates probably upogebiid shrimp that could not be produced under any condition other than sustained marine submergence overlying this were pure carbonate beach sands of a low energy regressive phase containing abundant remains of terrestrial and marine vertebrates and invertebrates the considerable diversity of this fauna along with taphonomic evidence from seabird remains indicates deposition by high run up waves over a minimum duration of months if not years the maximum duration has yet to be determined but probably did not exceed one or two thousand years the most abundant snails in this fauna are two species indicative of brackish water and high tide line showing that a ghyben herzberg lens must have existed at 20 m the nature of these sediments and fossil accumulation is incompatible with tsunami deposition and given the absence of evidence for tectonic uplift of the bermuda pedestal or platform provide proof that sea level during mis 11 exceeded 20 m a fact that has widespread ramifications for geologists biogeographers and human demographics along the world s coastlines

sea level history of past interglacial periods from uranium series dating of corals curacao leeward antilles islands curacao has reef terraces with the potential to provide sea level histories of interglacial periods ages of the hato upper unit of the lower terrace indicate that this reef dates to the last interglacial period marine isotope stage mis 5 5 on curacao this high sea stand lasted at least 8000 yr 126 to 118 ka elevations and age of this reef show that late quaternary uplift rates on curacao are low 0 026 0 054 m ka consistent with its tectonic setting ages of 200 ka for corals from the older cortalein unit of the lower terrace correlate this reef to mis 7 with paleo sea level estimates ranging from 3 3 m to 2 3 m the estimates are in agreement with those for mis 7 made from other localities and indicate that the penultimate interglacial period was a time of significant warmth on a par with the present interglacial period the 400 ka mis 11 middle terrace i on curacao dated by others may have formed from a paleo sea level of 8 3 to 10 0 m or less likely 17 m to 20 m the lower estimates are conservative compared to previous studies but still require major ice sheet loss from greenland and antarctica

depositional sequences and stratigraphy of the colon carbonate platform bocas del toro archipelago panama abstract the colon platform located in the bocas del toro region of panama was studied as a near modern analog for buried reefal platforms the platform has an areal extent of 90 km2 and formed in a convergent tectonic setting backarc under a tropical climatic regime the attached platform formed as part of a discontinuously rimmed shelf along the caribbean side of the isthmus of panama and consisted of mixed carbonates and siliciclastics based on field relations and strontium isotope stratigraphy three depositional sequences were identified in the near surface deposits of the uplifted platform a miocene to late pliocene lithic sandstone unit sequence 1 old bank formation forms the foundation of the platform coral rich limestone and coral rich siliciclastic units were deposited during both the late pliocene sequence 2 isla colon formation and early pleistocene sequence 3 urraca formation in sequences 2 and 3 the sediment composition and fauna show distinct differences between the windward and leeward sides of the platform with the main lithologic variable being the amount of siliciclastic sediment that was admixed with the biogenic carbonate sediments the siliciclastic deposits mud rich in sequences 2 and 3 exhibit lower permeability and relatively minor diagenetic modification and they lack major karst features conversely the more carbonate rich deposits are well cemented and strongly affected by meteoric dissolution and karstification this facies selective dissolution occurred when middle pleistocene regional uplift exposed the platform to a tropical climate with high rainfall earthquakes and associated uplift of the platform over the past 1 myr intensely fractured the limestone fracture porosity has contributed to rapid infiltration of meteoric water and pervasive dissolution that resulted in numerous vertical sinks as well as an extensive network of horizontal conduits a large incised channel feature connects several of the pre existing caves and conduits the colon platform limestone is a product of an equatorial humid carbonate system and is of size similar to platforms of oligo miocene age near malaysia sarawak indonesia and farther north in the south china sea

decreasing uplift rates and pleistocene marine terraces settlement in the central lesser antilles fore arc la desirade island 16 n this study investigates the lesser antilles fore arc at the latitude of guadeloupe archipelago and evidences that la desirade island the eastermost island of the forearc displays a staircase coastal sequence including four uplifted marine terraces and an upper reefal platform with mean shoreline angle elevations ranging from 10 to 210 m above sea level asl the platform paleobathymetry is constraint by a detailed analysis of the sediments we propose a revised morphostratigraphy for this coastal sequence including 5 paleo shorelines based on six u th dating from aragonitic corals from the three lowest terraces combined with paleobathymetric analysis of the fossil corals present in the upper platform terrace and upper platform carving of construction periods occurred during marine isotopic stages mis 5e mis 9 and during the intervals mis 15 17 mis 19 25 and mis 31 49 upper coral reef platform our results evidence a bulk decreasing uplift rate since early calabrian to present day clearly documented since 310 ka mis 9 from 0 14 to 0 19 to ca 0 mm y our data are consistent with first the transient influence of the subducting oceanic tiburon ridge during calabrian then with other parametres of the subduction zone since late calabrian to present day dip of the slab basal erosion of the upper plate inherited structures

mid late holocene sea level variability in eastern australia a re analysis of sea level data from eastern australia based on 115 calibrated c 14 ages is used to constrain the origin timing and magnitude of sea level change over the last 7000 years we demonstrate that the holocene sea level highstand of 1 0 1 5 m was reached 7000 cal yr bp and fell to its present position after 2000 yr bp these findings are in contrast to most previous studies that relied on smaller datasets and did not include the now common conversion of conventional c 14 ages to calendar years during this 5000 year period of high sea level growth hiatuses in oyster beds and tubeworms and lower elevations of coral microatolls are interpreted to represent short lived oscillations in sea level of up to 1 m during two intervals beginning c 4800 and 3000 cal yr bp the rates of sea level rise and fall 1 2 mm yr 1 during these centennial scale oscillations are comparable with current rates of sea level rise the origin of the oscillations is enigmatic but most likely the result of oceanographic and climatic changes including wind strengths ice ablation and melt water contributions of both greenland and antarctic ice sheets

role of regional extension and uplift in the plio pleistocene evolution of the aksu basin sw turkey the aksu basin within the isparta angle area of sw turkey documents plio pleistocene crustal processes at the interface between the tauride mountains and the eastern mediterranean sea basin sedimentation began in the late miocene following an earlier history of emplacement of mesozoic allochthonous units antalya complex miocene basin development and localized late miocene compression aksu phase late miocene early pliocene transtension deformed the aksu basin exploiting pre existing zones of structural weakness during early mid pliocene muddy sediments accumulated in a shallow shelf sea 2 and locally thick up to 250 m cool water antalya tufa deposits then followed prior to glacial times initial localized lacustrine carbonate deposition was followed by development of mainly algal carbonates that are thickest in the west the terraced nature of the tufa terraces at 300 250 100 m above present sea level is explained in terms of fluvial processes regional comparisons suggest a two stage history for the aksu basin first late miocene early pliocene transtension and subsidence secondly late pliocene early pleistocene rifting and marginal uplift the overall tectonic setting reflects interplay between supra subduction zone extension and tectonic escape of anatolia westwards towards the aegean

relation of alkaline volcanism and active tectonism within the evolution of the isparta angle sw turkey the isparta angle ia is formed along the boundary of the african and eurasian plates by ne and nw striking faults north of the antalya gulf in sw turkey the ne striking strike slip burdur fault bounds the ia to the west and is probably the continuation of the pliny system of the hellenic arc the nw striking aksehir fault bounds it to the east platform type parautochthonous mesozoic carbonate sequences such as the beydag and anamas akseki occur in the western and eastern parts of the ia respectively whereas allochthonous ophiolite nappes include the antalya beysehir hoyran and lycian nappes the ia and adjacent areas are divided into three areas the teke the antalya and the akseki fragments by ne nw and n striking active strike slip faults with normal components ia region volcanics are alkaline and hyperkaline in character potassic ultrapotassic and locally occur as subvolcanic stocks and dikes they can be traced between the afyon and isparta regions these volcanics consist mainly of

sea level highstands over the last 500 000 years evidence from the ironshore formation on grand cayman british west indies abstract the ironshore formation up to 19 m thick in the rogers wreck point area of grand cayman is divided into the unconformity bounded units a b c and d the unconformities are highlighted by caliches and or terra rossa th u dates from aragonitic corals indicate that unit a formed at 400 ka unit b 346 ka unit c 229 ka and unit d 131 ka these ages correlate with the highstands of the last four interglacial periods and probably represent marine isotope stages 5 unit d 7 unit c 9 unit b and 11 unit a the limestones in units a d which have similar biotic and lithologic characteristics represent deposition in shallow water on a narrow coastal shelf unit a has a high faunal diversity and was deposited in open marine conditions whereas units b c and d were deposited in quieter water lagoons that probably had fringing reefs along their sea ward edges although grand cayman is located on the cayman ridge close to an active spreading center and transform fault the island has undergone little or no vertical movement over the last 500 ky available evidence indicates that sea level at the time of deposition of each unit relative to present sea level was unit a 9 0 to 5 5 m unit b 3 0 to 0 5 m unit c 2 5 to 1 1 m and unit d 2 5 to 6 0 m these data are good estimates of eustatic sea level highstands over the last 500 ky