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

an alternative interpretation of the cayman trough evolution from a reidentification of magnetic anomalies magnetic data were collected during the wilkes 1973 and seacarib ii 1987 cruises to the cayman trough a new interpretation of magnetic data is carried out an isochron pattern is drawn up from our anomaly identifications an early eocene age 49 ma ypresian for cayman trough opening is proposed instead of the late oligocene or middle eocene ages suggested by previous studies our plate tectonic reconstruction is simpler and fits the on land geology jamaica and cuba and the tectonics our reconstruction shows a southward propagation of the spreading centre between magnetic anomalies 8 and 6 26 and 20 ma the trough width increases by 30 km in this period the southward propagation of the cayman spreading centre from the middle oligocene to the early miocene induced the development of the restraining bend of the swan islands the formation of a 1 km high scarp on the eastern trace of the cayman trough transform fault walton fault and the formation of a pull apart basin hendrix pull apart magnetic anomalies and magnetization maps give information about the deformation and the rocks the proposed evolutionary model of the cayman trough from the inception of seafloor spreading to the present configuration is presented in relation to the tectonic escape of the northern boundary of the caribbean plate from the maastrichtian to the present

along strike segmentation in the northern caribbean plate boundary zone hispaniola sector tectonic implications abstract the north american noam plate converges with the caribbean carib plate at a rate of 20 0 0 4 mm yr towards 254 1 plate convergence is highly oblique 20 10 resulting in a complex crustal boundary with along strike segmentation strain partitioning and microplate tectonics we study the oblique convergence of the noam and carib plates between southeastern cuba to northern puerto rico using new swath multibeam bathymetry data and 2d multi channel seismic profiles the combined interpretation of marine geophysical data with the seismicity and geodetic data from public databases allow us to perform a regional scale analysis of the shallower structure the seismotectonics and the slab geometry along the plate boundary due to differential rollback between the noam oceanic crust north of puerto rico and the relative thicker bahamas carbonate province crust north of hispaniola a slab tear is created at 68 5 w the northern margin of puerto rico records the oblique high dip subduction and rollback of the noam plate below the island arc those processes have resulted in a forearc transpressive tectonics without strain partitioning controlled by the septentrional oriente fault zone sofz and the bunce fault zone bfz meanwhile in the northern margin of hispaniola the collision of the bahamas carbonate province results in high plate coupling with strain partitioning sofz and northern hispaniola deformed belt nhdb in the northern haitian margin compression is still relevant since seismicity is mostly associated with the deformation front whereas strike slip earthquakes are hardly anecdotal although in hispaniola intermediate depth seismicity should disappear diffuse intermediate depth hypocenter remains evidencing the presence of remnant noam subducted slab below central and western hispaniola results of this study improve our understanding of the active tectonics in the ne caribbean that it is the base for future assessment studies on seismic and tsunamigenic hazard

block modeling with connected fault network geometries and a linear elastic coupling estimator in spherical coordinates geodetic observations of interseismic deformation provide constraints on the partitioning of fault slip across plate boundary zones the spatial distribution of both elastic and inelastic strain accumulation and the nature of the fault system evolution here we describe linear block theory which decomposes surface velocity fields into four components 1 plate rotations 2 elastic deformation from faults with kinematically consistent slip rates 3 elastic deformation from faults with spatially variable coupling and 4 homogeneous intrablock strain elastic deformation rates are computed for each fault segment in a homogeneous elastic half space using multiple optimal planar cartesian coordinate systems to minimize areal distortion and triangular dislocation elements to accurately represent complex fault system geometry block motions fault slip rates elastic coupling and internal block strain rates are determined simultaneously using a linear estimator with constraints from both geodetically determined velocity fields and geologic fault slip rate estimates we also introduce algorithms for efficiently implementing alternative fault network geometries to quantify parameter sensitivity to nonlinear perturbations in model geometry

hydrocarbon plays and global basin classification hydrocarbon plays and the global basin classification system have important connections after a basin has been classified its similarities or differences with other basins may be compared prolific hydrocarbon basins are categorized and the plays are compared to specific tectonic and depositional events some plays are controlled by basin initiating tectonic events such as interior fracture or interior sag and the type of sedimentation inherent in each basin type in more complex polyhistory basins oil and gas plays are commonly associated with combinations of various cycles or by basin modifying tectonics such as episodic wrenching subsidence foldbelts and basin tilt

cenozoic tectonics in the urumgi korla region of the chinese tien shan cenozoic deformation within the tien shan of central asia has accommodated part of the post collisional indentation of the indian plate into asia within the urumgi korla region of the chinese tien shan this occurred dominantly on thrusts with secondary strike slip faulting the gross pattern of deformation is of moderate to steeply dipping thrusts that have overthrust foreland basins to the north and south of the range the junggar and tarim basins respectively smaller foreland basins lie within the margins of the range itself turfan chai wo pu korla and qumishi basins these lie in the footwalls of local thrust systems both the turfan and the korla basins contain major thrusts within them they are complex foreland basins deformation has progressively affected regions further into the interior of the junggar basin and propagated into the interiors of the intermontane basins no unidirectional deformation front has passed across the tien shan in the neogene and quaternary an oligocene unconformity may indicate the time of the onset of the cenozoic deformation but most of the cenozoic molasse has been deposited after the palaeogene the rate of deposition in basins next to the uplifted ranges has increased since the onset of deformation there has been at least about 80 km of cenozoic shortening across this part of the tien shan cenozoic shortening is greater in sections of the range further west these are nearer to the northern margin of the indian indenter cenozoic compression has reactivated structures created by the two late palaeozoic collisions that created the ancestral tien shan these palaeozoic structures have exerted a strong control over the style and location of the cenozoic deformation

current block motions and strain accumulation on active faults in the caribbean the caribbean plate and its boundaries with north and south america marked by subduction and large intra arc strike slip faults are a natural laboratory for the study of strain partitioning and interseismic plate coupling in relation to large earthquakes here we use most of the available campaign and continuous gps measurements in the caribbean to derive a regional velocity field expressed in a consistent reference frame we use this velocity field as input to a kinematic model where surface velocities results from the rotation of rigid blocks bounded by locked faults accumulating interseismic strain while allowing for partial locking along the lesser antilles puerto rico and hispaniola subduction we test various block geometries guided by previous regional kinematic models and geological information on active faults our findings refine a number of previously established results in particular slip rates on the strike slip faults systems bounding the caribbean plate to the north and south and the kinematics of the gonave microplate our much improved gps velocity field in the lesser antilles compared to previous studies does not require the existence of a distinct northern lesser antilles block and excludes more than 3 mm yr of strain accumulation on the lesser antilles puerto rico subduction plate interface which appears essentially uncoupled the transition from a coupled to an uncoupled subduction coincides with a transition in the long term geological behavior of the caribbean plate margin from compressional hispaniola to extensional puerto rico and lesser antilles a characteristics shared with several other subduction systems

statistical tests of additional plate boundaries from plate motion inversions we have investigated the application of the f ratio test a standard statistical technique to the results of relative plate motion inversions the method tests whether the improvement in fit of the model to the data resulting from the addition of another plate to the model is greater than that expected purely by chance this approach appears to be useful in determining whether additional plate boundaries are justified we confirm previous results favoring separate north american and south american plates with a boundary located between 30 n and the equator using chase s global relative motion data we show that in addition to separate west african and somalian plates separate west indian and australian plates with a best fitting boundary between 70 e and 90 e can be resolved these results are generally consistent with the observation that the indian plate s internal deformation extends somewhat westward of the ninetyeast ridge the relative motion pole is similar to minster and jordan s and predicts the nw se compression observed in earthquake mechanisms near the ninetyeast ridge

a model for tectonic rotations about a vertical axis abstract the rotation of a rigid ellipsoidal inclusion within a highly viscous fluid orientated so that two of the principal axes remain horizontal is used as a model for the rotation of crustal inclusions in wide zones of continental deformation this model is also applicable to other geological problems involving the rotation of inclusions in a matrix the pattern of behaviour in such a model is shown to be complex in general the rotation rate of the inclusion is a function of all components of the velocity field of the deforming medium and the horizontal aspect ratio of the inclusion however for a given velocity field this aspect ratio must exceed a critical value before the inclusion can rotate continuously inclusions with lower aspect ratios will rotate for a certain range of orientations in an opposite direction to the sense of shear in the deforming zone the possibility of the inclusion changing shape during rotation adds to the complexity of behaviour

geology and geochemistry of bitumen vein deposits at ghost city junggar basin northwest china veins of solid bitumen occur in cretaceous sandstones at the northwest margin of the junggar basin china the bitumen has a low aromaticity and a composition comparable to gilsonite the bitumen contains abundant steranes and terpanes and s carotane although most n and i alkanes have been removed which is characteristic of the local crude oil the sterane and triterpane maturity parameters show that the bitumen local crude oil and source rocks are all mature bitumen wallrock relationships suggest that the host sandstone was not completely consolidated at the time of emplacement of the bitumen veins although bitumen emplacement was a relatively late diagenetic event the burial history for the northwest junggar basin shows that hydrocarbon generation from the assumed upper permian source rocks commenced in late triassic early jurassic times and suggests that rapid hydrocarbon generation may have resulted in overpressure contributing to the bitumen emplacement

gps estimates of microplate motions northern caribbean evidence for a hispaniola microplate and implications for earthquake hazard summary we use elastic block modelling of 126 gps site velocities from jamaica hispaniola puerto rico and other islands in the northern caribbean to test for the existence of a hispaniola microplate and estimate angular velocities for the gonave hispaniola puerto rico virgin islands and two smaller microplates relative to each other and the caribbean and north america plates a model in which the gonave microplate spans the whole plate boundary between the cayman spreading centre and mona passage west of puerto rico is rejected at a high confidence level the data instead require an independently moving hispaniola microplate between the mona passage and a likely diffuse boundary within or offshore from western hispaniola our updated angular velocities predict 6 8 1 0 mm yr 1 of left lateral slip along the seismically hazardous enriquillo plantain garden fault zone of southwest hispaniola 9 8 2 0 mm yr 1 of slip along the septentrional fault of northern hispaniola and 14 15 mm yr 1 of left lateral slip along the oriente fault south of cuba they also predict 5 7 1 mm yr 1 of fault normal motion in the vicinity of the enriquillo plantain garden fault zone faster than previously estimated and possibly accommodated by folds and faults in the enriquillo plantain garden fault zone borderlands our new and a previous estimate of gonave caribbean plate motion suggest that enough elastic strain accumulates to generate one to two mw 7 earthquakes per century along the enriquillo plantain garden and nearby faults of southwest hispaniola that the 2010 m 7 0 haiti earthquake ended a 240 yr long period of seismic quiescence in this region raises concerns that it could mark the onset of a new earthquake sequence that will relieve elastic strain that has accumulated since the late 18th century

regional stratigraphy of the zagros fold thrust belt of iran and its proforeland evolution the latest neoproterozoic through phanerozoic stratigraphy of the zagros fold thrust belt of iran has been revised in the light of recent investigations the revised stratigraphy consists of four groups of rocks each composed of a number of unconformity bounded megasequences representing various tectonosedimentary settings in the lowest group ranging in age from latest precambrian to devonian the uppermost neoproterozoic to middle cambrian rocks constitute a megasequence of evaporites siliciclastic deposits and interlayered carbonates which were deposited in pull apart basins that developed by the najd strike slip fault system this megasequence is overlain by a second one middle to late cambrian in age which consists of shallow marine siliciclastic and carbonate rocks representing deposition in an epicontinental platform the overlying shales siltstones and partly volcanogenic sandstones of ordovician silurian and devonian age are local remnants of stratigraphic units that were extensively eroded during development of several major unconformities the second group consists of two megasequences one permian and the other triassic composed of widespread transgressive basal siliciclastic rocks and overlying evaporitic carbonates of an equatorial epi pangean very shallow platformal sea the third group is composed of four megasequences formed of shallow and deep water carbonates with some siliciclastic and evaporite deposits which accumulated on a neo tethyan continental shelf during earliest jurassic through late turonian time the fourth group comprises siliciclastic and carbonate deposits of a largely underfilled nw to se trending forward and backward migrating late cretaceous to recent proforeland basin which has evolved as an integral part of the zagros orogen this last group consists of three megasequences ix x and xi with distinctive lateral and vertical facies variations which reflect specific tectonic events megasequence ix comprises uppermost turonian to middle maastrichtian prograding and retrograding siliciclastic and carbonate deposits whose accumulations reflect emplacement obduction of ophiolite slivers and subsequent collisional events in the zagros orogen megasequence x consists of uppermost maastrichtian to upper eocene siliciclastic and carbonate rocks which deposited first progradationally in front of the zagros orogenic wedge with reduced contractional tectonic activity and then retrogradationally due to intensified thrust stacking in the interior parts of the orogen megasequence xi consists of oligocene and lower miocene carbonate strata deposited retrogradationally shortly after a period of intensified late eocene thrust faulting in the deformational wedge and an overlying succession of upward coarsening northeasterly derived siliciclastic deposits of lower miocene to recent age which are composed of erosional byproducts of the southwest vergent zagros thrust sheets

spatial characteristics of middle devonian oils and non associated gases in the rainbow area northwest alberta previous studies indicate that the middle devonian of the rainbow sub basin represents a closed petroleum system with the muskeg evaporite acting as the regional seal to investigate the spatial and compositional characteristics of hydrocarbons in this area multivariate statistical methods were used to study the geochemical signatures of a suite of middle devonian oils and analyze the geographic distribution characteristics of the non associated gas accumulations in the sub basin the results suggest that there are two genetic groups of oils derived from slightly different source rocks geographic correlation of an oil group with a particular depositional facies indicates that communication between source and reservoir is the primary control on the variation of spatial characteristics of the oils geographic distribution characteristics of the non associated gas accumulations oil pool size and reservoir character suggest that cross formational migration of hydrocarbon may have occurred in major fracture systems the findings of this study may provide useful clues for future oil and gas exploration in this and adjacent relatively unexplored regions

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

seismic hazard of the enriquillo plantain garden fault in haiti inferred from palaeoseismology the enriquillo plantain garden fault zone is the primary plate bounding fault system in haiti and was initially thought to be responsible for the 2010 earthquake palaeoseismic analyses of the fault system indicate that it ruptured during a large earthquake in either 1750 or 1770 but did not rupture during the 2010 earthquake the enriquillo plantain garden fault zone is recognized as one of the primary plate bounding fault systems in haiti1 2 the strike slip fault runs adjacent to the city of port au prince and was initially thought to be the source of the 12 january 2010 mw 7 0 earthquake haiti experienced significant earthquakes in 1751 and 1770 refs 3 4 5 but the role of the enriquillo plantain garden fault zone in these earthquakes is poorly known we use satellite imagery aerial photography light detection and ranging lidar and field investigations to document quaternary activity on the enriquillo plantain garden fault we report late quaternary left lateral offsets of up to 160 m and a set of small offsets ranging from 1 3 to 3 3 m that we associate with one of the eighteenth century earthquakes the size of the small offsets implies that the historical earthquake was larger than mw 7 0 but probably smaller than mw 7 6 we found no significant surface rupture associated with the 2010 earthquake the lack of surface rupture coupled with other seismologic geologic and geodetic observations6 7 suggests that little if any accumulated strain was released on the enriquillo plantain garden fault in the 2010 earthquake these results confirm that the enriquillo plantain garden fault remains a significant seismic hazard

burial dissolution of micrite in middle east carbonate reservoirs jurassic cretaceous keys for recognition and timing abstract this paper discusses burial diagenesis and especially a burial dissolution phase and its effects on micrite microtexture in reservoirs in the middle east three microporous reservoirs were selected the cenomanian mishrif formation in iraq the kimmeridgian tithonian arab d and the barremian kharaib formations both in abu dhabi staining cathodoluminescence and scanning electron microscopy were used for petrographic observations in the selected reservoirs three typical micrite microtextures are distinguished micro rhombic compact anhedral and rounded the chronology of diagenesis based on petrographic observations shows that mineralogical stabilisation through high magnesian calcite replacement by low magnesian calcite led to the formation of micro rhombic micrites non reservoir facies such as seals present compact anhedral micrites correlation between these micrites and high aluminium content suggests alumino silicate minerals clays as a catalyst for pressure dissolution and thus for reservoir degradation through cementation micrites from the upper part of oil reservoirs are dissolved during burial diagenesis dissolution is responsible for rounded shape and for reduction of crystal size it also implies pore diameter and pore throat size enlargement comparison of porosity and permeability with scanning electron microscope data confirms that rounded micrites are better reservoirs than micro rhombic micrites

interseismic plate coupling and strain partitioning in the northeastern caribbean summary the northeastern caribbean provides a natural laboratory to investigate strain partitioning its causes and its consequences on the stress regime and tectonic evolution of a subduction plate boundary here we use gps and earthquake slip vector data to produce a present day kinematic model that accounts for secular block rotation and elastic strain accumulation with variable interplate coupling on active faults we confirm that the oblique convergence between caribbean and north america in hispaniola is partitioned between plate boundary parallel motion on the septentrional and enriquillo faults in the overriding plate and plateboundary normal motion at the plate interface on the northern hispaniola fault to the east the caribbean north america plate motion is accommodated by oblique slip on the faults bounding the puerto rico block to the north puerto rico subduction and to the south muertos thrust with no evidence for partitioning the spatial correlation between interplate coupling strain partitioning and the subduction of buoyant oceanic asperities suggests that the latter enhance the transfer of interplate shear stresses to the overriding plate facilitating strike slip faulting in the overriding plate the model slip rate deficit together with the dates of large historical earthquakes indicates the potential for a large m w7 5 or greater earthquake on the septentrional fault in the dominican republic similarly the enriquillo fault in haiti is currently capable of a m w7 2 earthquake if the entire elastic strain accumulated since the last major earthquake was released in a single event today the model results show that the puerto rico lesser antilles subduction thrust is only partially coupled meaning that the plate interface is accumulating elastic strain at rates slower than the total plate motion this does not preclude the existence of isolated locked patches accumulating elastic strain to be released in future earthquakes but whose location and geometry are not resolvable with the present data distribution slip deficit on faults from this study are used in a companion paper to calculate interseismic stress loading and together with stress changes due to historical earthquakes derive the recent stress evolution in the ne caribbean

seismic hazard along the southern boundary of the gonave microplate block modelling of gps velocities from jamaica and nearby islands northern caribbean summary we use block modelling of gps site velocities from jamaica and nearby islands including hispaniola to test alternative plate boundary geometries for deformation in jamaica and estimate slip rates along the island s major fault zones relative to the caribbean plate gps sites in northern jamaica move 6 0 0 5 mm yr 1 to the wsw constituting a lower bound on the motion of the gonave microplate across its southern boundary in jamaica obliquely convergent motion of all 30 gps sites on and near jamaica relative to the island s e w trending strike slip faults may be partitioned into 2 6 0 6 mm yr 1 of n s shortening across submarine faults south of jamaica and 5 6 mm yr 1 of e w motion guided by geological and seismic information about the strikes and locations of faults in jamaica inverse block modelling of the regional gps velocities rejects plate boundary configurations that presume either a narrow plate boundary in jamaica or deformation concentrated across a restraining bend defined by the topographically high blue mountains of eastern jamaica the best fitting models instead place most deformation on faults in central jamaica the 4 5 mm yr 1 slip rate we estimate for the plantain garden fault and blue mountain restraining bend of southeastern jamaica implies significant seismic hazard for the nearby capital of kingston

late holocene structural style and seismicity of highly transpressional faults in southern haiti author s wang j mann p stewart rr abstract 2018 the authors the devastating 2010 haiti earthquake mw 7 0 was caused by rupture of the leog ne blind thrust fault located 5 km north of the 1 200 km long left lateral enriquillo plantain garden fault zone epgfz unexpectedly the epgfz remained largely quiescent or slightly reactivated during the 2010 earthquake nevertheless the epgfz still formed a major crustal boundary between a coseismically uplifted lowland north of the epgfz and a subsided area in the highlands south of the fault here we use high resolution sonar data from two haitian lakes that straddle the epgfz to demonstrate the presence of a 10 to 15 km wide 120 km long late holocene fold thrust belt which deforms clastic lowland basins along the northern edge of the epgfz in the eastern part of the study area sonar results from lake azuey show that the linear trace of the epgfz cutting the holocene lake bed is more deeply buried and less active than the adjacent newly discovered northwest striking northeast dipping jimani thrust fault that is part of the adjacent transpressional belt of en echelon thrusts and folds this structural relationship between a less active epgfz and more recently active transpression related jimani thrust is remarkably similar to the 2010 epicentral area 70 km to the west between the less active epgfz and seismogenic northeast dipping leog ne thrust during the 2010 haiti earthquake in this complex transpressional zone we propose that coseismic deformation alternates at recurrence intervals of centuries between oblique transpression related structures leog ne jimani and trois baies thrusts and the main strike slip plate boundary fault zone epgfz

crustal thickness and bulk poisson ratios in the dominican republic from receiver function analysis abstract the dominican republic dr comprises the eastern two thirds of the island of hispaniola which is located on the caribbean north american plate boundary previous studies have described the shallow structure and stratigraphy of the island but due to a dearth of broadband seismic data little is known about the lower crust and mantle since august 2014 thirteen broadband three component seismic stations have been deployed temporarily in the dr they are combined with four permanent broadband stations in the dr and three in neighboring haiti to enhance studies of hispaniola s lower crust and upper mantle we report results of a receiver function study using teleseismic data recorded by these stations specifically we compute receiver functions and determine crustal properties via h stacking we propose additional intracrustal and upper mantle layers based on identifications of prominent and coherent p to s converted phases observed in receiver function gathers our results show that crustal thickness varies beneath the island of hispaniola over the range 13 47 km with a median of 24 km and bulk vp vs ratios vary over 1 58 1 99 with median 1 79 receiver function modeling reveals intracrustal discontinuities at station paph port au prince haiti at a depth of 8 0 km station jidr jimani dr 8 8 km depth and sddr sabaneta dr 15 8 km depth additional discontinuities appear in the upper mantle beneath paph 60 1 km depth pcdr punta cana 60 km sdd santo domingo 70 km and sc01 santiago 81 km two north south cross sections show variations in bulk vp vs ratios that are consistent with expectations based upon surface geology but variations in crustal thickness are more scattered and do not conform to expectations from simple tectonic models of hispaniola s formation our stacking results reveal consistency between vp vs ratios in four distinct regions which are consistent with the compositional domains identified by previous studies

neotectonics of hispaniola plate motion sedimentation and seismicity at a restraining bend abstract the pattern of neogene faulting volcanism and sedimentation in hispaniola helps to resolve a problem that arises in attempting to determine the direction of caribbean plate motion from earthquakes alone namely how well do earthquake mechanisms define plate motion hispaniola occupies a compressional north step or restraining bend in the generally east west trending motagua cayman trough puerto rico trench fault system which marks an active plate boundary zone pbz of left lateral strike slip motion between the north america and caribbean plates four areas are distinguishable in hispaniola from field mapping and from the interpretation of satellite imagery and conventional aerial photographs two of these areas consist of active left lateral strike slip fault systems that roughly define the northern and southern coasts of the island the structure of both fault systems suggest a roughly east west trending direction of relative plate motion consistent with previous findings the intervening area consists of en echelon mountain ranges thrust up at the restraining bend from the early miocene a pleistocene volcanic province within this area is interpreted as defining a diffuse extensional fault termination of the southern strike slip fault zone the fourth area in eastern hispaniola is interpreted as being underthrust by discontinuous fragments of lithosphere in response to convergence at the restraining bend it appears possible that thinner young island arc lithosphere may be more prone to subduction than to escape or flaking processes that are more important in older more buoyant lithosphere

downstream evolution of turbiditic channel complexes in the pab range outcrops maastrichtian pakistan the pab formation consists of deltaic and turbiditic sediments which were deposited during the late maastrichtian on the indo pakistani passive margin the margin geometry has been restored in the pab range from a regional transect 120 km long two superposed turbiditic systems onlap the slope carbonates and completely pinch out southward the lowest turbiditic system lower pab is a sand rich basin floor fan which consists of sand rich channel complexes distally passing to lobes northward this basin floor fan is overlain by a mud rich slope fan formed during the subsequent sea level rise which drowned the shelf the upper turbiditic system upper pab is a sand rich slope fan formed during the progradation of a deltaic system in the shelf setting it consists of prograding tabular lobes passing upward to conglomeratic channels and thins out northwards the lower pab turbiditic system consists of three channel complexes lp1 2 3 organised in a backstepping succession each channel complex has a multi storey internal architecture resulting from the amalgamation of several individual turbiditic channels five major facies associations have been determined in the lp3 channel complex fa 1 corresponds to polygenic and monogenic debris flows fa 2 to high density gravelly or sandy turbidites fa 3 to by pass deposits fa 4 to thin bedded turbidites spill over lobes and levees and fa 5 to hemipelagites the downstream evolution of the lp3 channel complex can be studied from canyon to mid fan settings where it is confined in the canyon the channel complex is 50 m thick and 1 km large and shows a high sand shale ratio the development of overflow deposits is limited and occurs only at the top of the channel complex at the canyon mouth the channel complex is still deeply incised but overflow deposits start to expand laterally as a result of the decreased confinement by pass facies here are well developed and are related to hydraulic jump processes in the mid fan setting the channel complex widens and the sand shale ratio decreases erosion at the channel base is less developed whereas internal and external levees are well developed spill over lobes form the last stage of the channel complex infill the internal geometry of the channel complexes is a result of a complex interaction between lateral confinement by pass and lateral migration processes

the 2010 haiti earthquake a complex fault pattern constrained by seismologic and tectonic observations after the january 12 2010 haiti earthquake we deployed a mainly offshore temporary network of seismologic stations around the damaged area the distribution of the recorded aftershocks together with morphotectonic observations and mainshock analysis allow us to constrain a complex fault pattern in the area almost all of the aftershocks have a n s compressive mechanism and not the expected left lateral strike slip mechanism a first order slip model of the mainshock shows a n264 e north dipping plane with a major left lateral component and a strong reverse component as the aftershock distribution is sub parallel and close to the enriquillo fault we assume that although the cause of the catastrophe was not a rupture along the enriquillo fault this fault had an important role as a mechanical boundary the azimuth of the focal planes of the aftershocks are parallel to the north dipping faults of the transhaitian belt which suggests a triggering of failure on these discontinuities in the western part the aftershock distribution reflects the triggering of slip on similar faults and or alternatively of the south dipping faults such the trois baies submarine fault these observations are in agreement with a model of an oblique collision of an indenter of the oceanic crust of the southern peninsula and the sedimentary wedge of the transhaitian belt the rupture occurred on a wrench fault at the rheologic boundary on top of the under thrusting rigid oceanic block whereas the aftershocks were the result of the relaxation on the hanging wall along pre existing discontinuities in the frontal part of the transhaitian belt

the northern caribbean plate boundary in the jamaica passage structure and seismic stratigraphy multibeam bathymetry data and multichannel seismic reflection profiles have been collected at the end of 2012 along the enriquillo plantain garden fault zone epgfz in the jamaica passage between jamaica and hispaniola analysis of the data set reveals the tectonic evolution and the stratigraphic complexity of the northern caribbean boundary stratigraphic correlations with previous marine and on land studies are proposed to place the identified seismic sequences in their regional tectonic history two distinct crustal domains are interpreted typical stratigraphic sequences for the rifted blocks of the eastern cayman trough margin are identified in five basins of the jamaica passage highlighting the eastward limit of the cayman trough margin these inherited basins are deformed and folded during a first phase of compression that could correspond to the regional tectonic rearrangement recorded in the early miocene about 20 ma a distinct crustal domain that we propose to relate to the carib beds caribbean typical reflectors a b and v is identified in the southern part of the jamaica passage indicating that the caribbean large igneous province could extend up to the extreme northeast part of the lower nicaragua rise the left lateral epgfz currently cuts across two pre existing basins the morant and matley basins during the activity of the epgfz these basins are deformed and folded indicating a second phase of compression in contrast the navassa basin located in the middle of the jamaica passage results from the strike slip motion of the epgfz and is interpreted as an asymmetrical basin bordered by the epgfz only on its northern side

from transcurrent faulting to frontal subduction a seismotectonic study of the northern caribbean plate boundary from cuba to puerto rico recent marine and onland geophysical and geological investigations along the northern caribbean plate boundary call for a review of its tectonic interpretation in the light of a new compilation of the seismological data avalaible from cuba to puerto rico we show that the shallow seismicity in the northeastern caribbean is concentrated along an east west trending lineament corresponding to the trace of the major strike slip fault system the most intense seismicity is located around restraining bends such as southern cuba and northern hispaniola the stress and strain distribution deduced from focal mechanisms and microtectonic analysis lead us to infer a small n s convergence component associated with the major eastward strike slip motion of the caribbean plate versus north america earthquake distribution and focal mechanisms suggest the existence of a lithospheric slab inherited from the frontal subduction under the lesser antilles diping down under puerto rico and eastern hispaniola we propose a model in which this slab is disconnected from the atlantic oceanic lithosphere by transcurrent faulting along the plate boundary

acidic biomarkers from albacora oils campos basin brazil abstract acidic biomarkers of 8 different oil samples from albacora oil field campos basin brazil were analyzed in order to obtain additional information about biodegradation and thermal evolution for this purpose we selected oils lacustrine saline origin showing different biodegradation levels and at different distances from the fault that acted as migration pathway in the area previous analyses using hydrocarbon biomarkers suggested a mix of oil charges characterizing two distinct oil cycles interrupted by meteoric water circulation in these reservoirs analyses of the naphthenic acid biomarkers revealed a parallelism between the hydrocarbon and the acidic biomarkers notwithstanding there is evidence that the carboxylic acid biomarkers more resistent to biodegradation can provide information on past reservoir history when most important neutral biomarkers have been biodegraded the limitations to the use of these biomarkers are their de novo synthesis in the biodegradation process and the complexity of the sample manipulation prior to the analysis

segmentation and kinematics of the north america caribbean plate boundary offshore hispaniola we explored the submarine portions of the enriquillo plantain garden fault zone epgfz and the septentrional oriente fault zone sofz along the northern caribbean plate boundary using high resolution multi beam echo sounding and shallow seismic reflection the bathymetric data shed light on poorly documented or previously unknown submarine fault zones running over 200 km between haiti and jamaica epgfz and 300 km between the dominican republic and cuba sofz the primary plate boundary structures are a series of strike slip fault segments associated with pressure ridges restraining bends step overs and dogleg offsets indicating very active tectonics several distinct segments 50 to 100 km long cut across pre existing structures inherited from former tectonic regimes or bypass recent morphologies formed under the current strike slip regime along the most recent trace of the sofz we measured a strike slip offset of 16 5 km which indicates steady activity for the past 1 8 ma if its current gps derived motion of 9 8 2 mm yr has remained stable during the entire quaternary

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

behavior of the brittle crust in wide plate boundary zones in wide and active continental plate boundary zones ductile flow in the deeper and strong parts of the lithosphere may control crustal deformation this is likely if average resistive shear stresses on faults in the brittle crust are much less than 108 pa and the underlying bulk effective viscosity is much greater than 1021 pa s in this case a simple model of distributed deformation referred to as the floating block model may be useful this treats the crust as an array of rotating and translating rigid blocks which are floating on an underlying continuous flow with a constant rheology the model is analyzed in detail in this paper because it has the potential to link detailed observations of crustal deformation with the large scale flow crustal blocks are defined by at least two sets of faults the kinematics of crustal deformation can be described in terms of the motions of these blocks both the relative motion on block boundaries faults and block tilting about a horizontal axis can be described in terms of the underlying flow and block rotation about a vertical axis however rotations about a vertical axis which are an important component of the crustal deformation will depend not only on the underlying flow but also on the shape orientation and arrangement of the crustal blocks the average rotation rate about a vertical axis over finite rotations will be significantly different from that predicted at any instant also the rotation history is considerably complicated if as is likely the underlying flow field or block shape has changed with time these aspects of crustal deformation are discussed with reference to real zones of active deformation in new zealand greece and western north america

geometry and structure associated to gas charged sediments and recent growth faults in the ebro delta spain abstract in the ebro delta ne spain small to large scale synsedimentary deformation has been observed by means of high and low resolution seismics correlated with a network of wells lithoseismic units involved are middle upper pleistocene clays and gravels and holocene deltaic sequence gassy sediments and large river floor pockmarks are identified from seismic profiles along the ebro delta gas charged sediments are identified by zones of acoustic turbidity and other acoustic anomalies on seismic profiles most of the gas is believed to be biogenic in origin resulting from the decay of organic matter contained within rapidly developing shelf margin deltas a group of large symmetric river floor pockmarks also occurs along the inner delta plain both on the river floor surface and buried in the sediment column listric fault geometry is a typical scope shaped plane with a steep upper surface 40 60 that passes downward into a horizontal shear plane the shear plane appears seismically as chaotic and convoluted high amplitude reflectors and is correlated with well data showing layers that include gravel sand and clays associated structural features include reverse drag of reflectors antithetic faults and fluid escapes methane water the growth faulting along the ebro delta includes a break away and thin near surface layer created by overstepping of a sandy holocene delta slope the over steeping lies down dip from growth faults along the shelf break the overall growth faults province appears to represent a deeper seated general movement of the delta mass involving differential loading overpressure of fluids diapiric movements and extensional tectonics that cause listric faults and associated structures at different scales the recent growth faults are regularly spaced with the distance between successive faults controlled by the depth to the detachment layer three main fault systems have been identified a first or primary system spaced 5 2 10 5 km above a detachment layer at 55 95 m deep a second system spaced 3 5 6 km and a third system spaced 1 5 2 5 km above a detachment layer at 25 30 m the slope angle calculated by empirical equations ranges between 0 5 and 1 0 for the three systems

complex rupture during the 12 january 2010 haiti earthquake initially the devastating mw 7 0 12 january 2010 haiti earthquake seemed to involve straightforward accommodation of oblique relative motion between the caribbean and north american plates along the enriquillo plantain garden fault zone here we combine seismological observations geologic field data and space geodetic measurements to show that instead the rupture process involved slip on multiple faults primary surface deformation was driven by rupture on blind thrust faults with only minor deep lateral slip along or near the main enriquillo plantain garden fault zone thus the event only partially relieved centuries of accumulated left lateral strain on a small part of the plate boundary system together with the predominance of shallow off fault thrusting the lack of surface deformation implies that remaining shallow shear strain will be released in future surface rupturing earthquakes on the enriquillo plantain garden fault zone as occurred in inferred holocene and probable historic events we suggest that the geological signature of this earthquake broad warping and coastal deformation rather than surface rupture along the main fault zone will not be easily recognized by standard palaeoseismic studies we conclude that similarly complex earthquakes in tectonic environments that accommodate both translation and convergence such as the san andreas fault through the transverse ranges of california may be missing from the prehistoric earthquake record

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

present day shortening in southern haiti from gps measurements and implications for seismic hazard abstract the 3 m inhabitant capital region of haiti severely affected by the devastating january 12 2010 m7 0 earthquake continues to expand at a fast rate accurate characterization of regional earthquake sources is key to inform urban development and construction practices through improved regional seismic hazard estimates here we use a recently updated global positioning system gps data set to show that seismogenic strain accumulation in southern haiti involves an overlooked component of shortening on a south dipping reverse fault along the southern edge of the cul de sac basin in addition to the well known component of left lateral strike slip motion this tectonic model implies that ground shaking may be twice that expected if the major fault was purely strike slip as assumed in the current seismic hazard map for the region

significant earthquakes on the enriquillo fault system hispaniola 1500 2010 implications for seismic hazard abstract historical records indicate frequent seismic activity along the north east caribbean plate boundary over the past 500 years particularly on the island of hispaniola we use accounts of historical earthquakes to assign intensities and the intensity assignments for the 2010 haiti earthquakes to derive an intensity attenuation relation for hispaniola the intensity assignments and the attenuation relation are used in a grid search to find source locations and magnitudes that best fit the intensity assignments here we describe a sequence of devastating earthquakes on the enriquillo fault system in the eighteenth century an intensity magnitude m i 6 6 earthquake in 1701 occurred near the location of the 2010 haiti earthquake and the accounts of the shaking in the 1701 earthquake are similar to those of the 2010 earthquake a series of large earthquakes migrating from east to west started with the 18 october 1751 m i 7 4 7 5 earthquake probably located near the eastern end of the fault in the dominican republic followed by the 21 november 1751 m i 6 6 earthquake near port au prince haiti and the 3 june 1770 m i 7 5 earthquake west of the 2010 earthquake rupture the 2010 haiti earthquake may mark the beginning of a new cycle of large earthquakes on the enriquillo fault system after 240 years of seismic quiescence the entire enriquillo fault system appears to be seismically active haiti and the dominican republic should prepare for future devastating earthquakes online material table listing small earthquakes and figures of intensity assignments and intensity magnitude estimates

relative motion between the caribbean and north american plates and related boundary zone deformation from a decade of gps observations global positioning system gps measurements in 1986 1994 and 1995 at sites in dominican republic puerto rico cuba and grand turk define the velocity of the caribbean plate relative to north america the data show eastward motion of the caribbean plate at a rate of 21 1 mm yr 1 standard error in the vicinity of southern dominican republic a factor of 2 higher than the nuvel 1a plate motion model prediction of 11 3 mm yr independent measurements on san andres island and an euler vector derived from these data also suggest a rate that is much higher than the nuvel 1a model available data combined with simple elastic strain models give the following slip rate estimates for major left lateral faults in hispaniola 1 the north hispaniola fault offshore the north coast of hispaniola 4 3 mm yr 2 the septentrional fault in northern dominican republic 8 3 mm yr and 3 the enriquillo fault in southern dominican republic and haiti 8 4 mm yr the relatively high plate motion rate and fault slip rates suggested by our study combined with evidence for strain accumulation and historical seismicity imply that seismic risk in the region may be higher than previous estimates based on low plate rate low fault slip rate models and the relatively low rate of seismicity over the last century

seismic hazard for cuba a new approach abstract a new seismic hazard study for cuba is presented in terms of maps and uniform hazard spectra uhs an earthquake catalog from 1502 to 2012 was prepared for the region 16 24 n and 67 86 w and was homogenized to m w and cleaned for aftershocks and foreshocks a 16 arm logic tree computation corresponding to four source branches and four ground motion prediction equations gmpes was conducted using only published gmpe relations due to a lack of local strong motion data for each source model the seismicity parameters and m max were developed the results were obtained and are presented in terms of maps and uhs graphs for a 475 year return period but results for other return periods are easily obtained the influence of different branch weighting in the logic tree was investigated with respect to the final results peak ground acceleration values for cuba were found to vary from less than 75 to 230 cm s 2

age and spreading history of the cayman trough as determined from depth heat flow and magnetic anomalies the opening of the cayman trough records aspects of relative motion between the north american and caribbean plates essential to accurate reconstruction of caribbean evolution assessment of opening rates based upon basement subsidence analysis as well as magnetic anomaly interpretation shows that the trough may have opened at one third to one half previously proposed rates depths to basement show that the crust has subsided away from the present axis in two stages a younger stage characterized by substantial and asymmetric greater to the east subsidence preceded by an older stage of slight increases of depth with distance depth to age relations calculated from subsidence curves which accommodate lateral as well as vertical cooling of the accreting slab indicate that the trough has opened at an overall rate of less than 15 mm yr since 25 30 ma and at 20 30 mm yr prior to 30 ma marine magnetic anomalies show lineations perpendicular to the trough including a distinct central anomaly but the pattern is neither well defined nor symmetrical about the present axis however partial anomaly sequences can be identified on both sides of the axis and the distribution of these sequences indicates that spreading may have involved frequent short ridge jumps mostly eastward the overall rate of opening as indicated by this interpretation of the magnetics is about 15 and 30 mm yr since and prior to 26 ma both subsidence and magnetics indicate that the trough opened by at least 45 50 ma

integrated geophysical geological modelling of the caledonian and precambrian basement of southern britian quantitative modelling of potential field data has been used to test and extend geological sections constructed for the new british geological survey tectonic map of britain and ireland three of the profiles cross part of the anglo brabant massif and provide new information on the nature of the pre mesozoic basement a profile across southern england passing just to the west of london suggests that a significant contribution to observed gravity variations in the region results from changes in the thickness of relatively low density lower palaeozoic rocks it also identifies a major deep seated body with relatively high magnetic susceptibility and low density which is interpreted as a precambrian cratonic core underlying the southeastern part of the midlands microcraton profiles across central and eastern england reveal major boundaries within the precambrian basement some of which coincide with structures mapped at surface a number of intrusions of probable caledonian age have been recognized including bodies beneath the widmerpool gulf and the wash those beneath the wash appear to lie in a discrete basement region which separates belts of more magnetic basement lying to the northwest and southeast

transpressional rupture of an unmapped fault during the 2010 haiti earthquake the enriquillo plantain garden strike slip fault accommodates the relative motion between the north american and caribbean plates and was thought to have ruptured during the 2010 haiti earthquake satellite data instead indicate that a blind thrust fault possibly related to the haitian fold thrust belt was responsible and caused some contractional deformation on 12 january 2010 a mw 7 0 earthquake struck the port au prince region of haiti the disaster killed more than 200 000 people and caused an estimated 8 billion in damages about 100 of the country s gross domestic product1 the earthquake was initially thought to have ruptured the enriquillo plantain garden fault of the southern peninsula of haiti which is one of two main strike slip faults inferred to accommodate the 2 cm yr 1 relative motion between the caribbean and north american plates2 3 here we use global positioning system and radar interferometry measurements of ground motion to show that the earthquake involved a combination of horizontal and contractional slip causing transpressional motion this result is consistent with the long term pattern of strain accumulation in hispaniola the unexpected contractional deformation caused by the earthquake and by the pattern of strain accumulation indicates present activity on faults other than the enriquillo plantain garden fault we show that the earthquake instead ruptured an unmapped north dipping fault called the leog ne fault the leog ne fault lies subparallel to but is different from the enriquillo plantain garden fault we suggest that the 2010 earthquake may have activated the southernmost front of the haitian fold and thrust belt4 as it abuts against the enriquillo plantain garden fault as the enriquillo plantain garden fault did not release any significant accumulated elastic strain it remains a significant seismic threat for haiti and for port au prince in particular

neotectonic structures and stress fields associated with oblique collision and forearc sliver formation in northern hispaniola implications for the seismic hazard assessment abstract active oblique collision between the caribbean and north america plates has led to the formation of the septentrional forearc sliver which is a wedge shaped crustal domain limited to the north by the north hispaniola subduction thrust and to the south by the septentrional fault zone sfz in northern hispaniola oblique collision of the bahamas platform began in the uppermost pliocene to early pleistocene and continues today collision related tectono stratigraphic processes include destruction of the shallow water carbonate forearc platform uplift and erosion of the cordillera septentrional and samana peninsula emergence of the cibao basin and syn tectonic deposition of alluvial fan systems the geometry and kinematics of neotectonics structures at all scales together with stress field solutions obtained from late cenozoic fault slip data show that the ene directed far stress field associated with collision triggered the formation of the wnw trending left lateral strike slip sfz the sfz thus represents the inland concave master fault bounding the septentrional forearc sliver subsidiary ene to ne trending left lateral strike slip faults r type and nne to ne trending normal and oblique faults t type controlled the internal deformation and subdivision into smaller tectonic blocks of the sliver the highly oblique convergence and the increase in frictional plate coupling associated with the underthrusting of the bahamas platform are the likely causes of the formation of this forearc sliver in the western cordillera septentrional and cibao basin an extensional regime is locally produced by the transfer of the left lateral movement to a southern splay of the sfz with the incorporation of a detached block to the septentrional forearc sliver during the middle pleistocene holocene the regional distribution of the modeled peak ground acceleration values indicates that the sfz is the greatest seismic hazard in northern hispaniola

lower plate geometry controlling the development of a thrust top basin the tectonosedimentary evolution of the ofanto basin southern apennines the ofanto basin is a pliocene pleistocene thrust top basin that formed with an unusual east west orientation along the frontal part of the southern apennine allochthon during the latest stages of tectonic transport its tectonic and sedimentary evolution was studied integrating field surveys biostratigraphic analyses and the interpretation of a large seismic grid well data and seismic interpretation indicate that a large east west trending normal fault underlies the northern margin of the basin displacing the apulian carbonates that form the foreland and the footwall of the southern apennine allochthon in our reconstruction the ofanto basin formed at the rear of the bulge caused by buttressing of the southern apennine allochthon against this normal fault in a second stage of contraction the footwall of the southern apennine allochthon was involved in deformation with a different trend from the normal faulting and buttressing this caused eastward tilting of the basin and broad folding around its eastern termination good stratigraphic constraints permit the age of buttressing to be defined as early pliocene and that of the shortening in the apulian carbonates as early pleistocene this study highlights the importance of early orogenic normal faults in conditioning the evolution of the frontal parts of orogenic wedges supplementary material a 3d reconstruction of the base of the pliocene deposits of the ofanto basin based on seismic interpretation is available at www geolsoc org uk sup18559

character of the caribbean gonave north america plate boundaries in the upper mantle based on shear wave splitting 1 we present new shear wave splitting measurements of sks skks pks and ssks phases from eight stations in the northern caribbean prior to this work shear wave splitting analysis of the northern caribbean boundary was only evaluated at a station in puerto rico stations that lie within several tens of kilometers of microplate boundaries have mean fast polarization directions parallel to the boundary and have delay times greater than 1 s stations more than several tens of kilometers away from microplate boundaries show no evidence for an anisotropic upper mantle stations in cuba and jamaica have fast axes oriented 100 with delay times of 1 5 s indicating that the east striking left lateral strike slip faults that define the north and south boundaries of the gonave microplate continue into the upper mantle a station located in antigua where the north america plate subducts beneath the caribbean plate has a high degree of splitting with the fast axis parallel to the trench based on our results the deformation related to the presence of microplates in the northern caribbean extends into the upper mantle

geochemical characterisation and genetic origin of oils and condensates in the south viking graben norway abstract geochemical analysis of oil and condensate samples from all major fields and discoveries in the norwegian south viking graben as well as source rock extracts of upper and middle jurassic source horizons was carried out to characterise reservoired hydrocarbons and establish genetic relationships the south viking graben is in a mature phase of exploration and this study aims at unravelling regional trends to improve predictions in exploration and will show the significance of the play models in the area seven hydrocarbon families have been identified based on interpretation of molecular and isotopic characteristics and multivariate analysis of biomarker data these families can be linked to three source horizons three families originate from different facies of the draupne formation and are characterised by pr ph ratios below 2 dominance of c 27 regular steranes over the c 29 homologues and carbon isotopic values for saturate and aromatic fraction lighter than 28 and 27 respectively the upper jurassic heather formation and the middle jurassic vestland group each source one group of hydrocarbons typical for heather sourced hydrocarbons are elevated pr ph ratios between 2 35 and 3 08 low ratios of c 27 c 29 regular steranes and average isotopic values of 28 4 13 c sat and 26 8 13 c aro hydrocarbons from a middle jurassic source are characterised by very heavy isotopic composition highest pr ph ratios of the data set and dominance of c 29 regular steranes over the c 27 homologues among other factors the two remaining families represent mixtures from upper and middle jurassic sources and are mainly encountered in the greater sleipner area the available data in this study allowed characterisation of 84 of the recoverable oil resources which proved that the main source rock in the area is the upper jurassic draupne formation the play concept including a draupne source and tertiary reservoir proves to be most prolific with 239 10 6 s m 3 of recoverable oil equalling 88 of the total characterised oil resources oils in these tertiary reservoirs are however likely to be affected by biodegradation based on the available data the zone of biodegradation in the south viking graben appears to be limited to depths above 2140 m and temperatures below 70 c

how transpressive is the northern caribbean plate boundary transpressive deformation at the northern caribbean plate boundary is accommodated mostly by two major strikeslip faults but the amount and location of accommodation of the compressional component of deformation is still debated we collected marine geophysical data including multi beam bathymetry and multichannel seismic reflection profiles along this plate boundary around hispaniola in the jamaica passage and in the gulf of gon ve the data set allows us to image the offshore active strike slip faults as well as the compressional structures we confirm that the enriquillo plantain garden fault zone epgfz in the jamaica passage has a primary strike slip motion as indicated by active left lateral strike sliprelated structures i e restraining bend asymmetrical basin en echelon pressures ridges and horsetail splay based on topographic cross sections across the epgfz we image a very limited compressional component if any for at least the western part of the jamaica passage toward the east of the jamaica passage the fault trace becomes more complex and we identify adjacent compressional structures in the gulf of gon ve distributed folding and thrust faulting of the most recent sediments indicate active pervasive compressional tectonics estimates of shortening in the jamaica passage and in the gulf of gon ve indicate an increase of the compressional component of deformation towards the east which nonetheless remains very small compared to that inferred from block modelling based on gps measurements

three dimensional dynamic rupture simulations across interacting faults the m w 7 0 2010 haiti earthquake the mechanisms controlling rupture propagation between fault segments during a large earthquake are key to the hazard posed by fault systems rupture initiation on a smaller fault sometimes transfers to a larger fault resulting in a significant event e g 2002 m7 9 denali usa and 2010 m7 1 darfield new zealand earthquakes in other cases rupture is constrained to the initial fault and does not transfer to nearby faults resulting in events of more moderate magnitude this was the case of the 1989 m6 9 loma prieta and 2010 m7 0 haiti earthquakes which initiated on reverse faults abutting against a major strike slip plate boundary fault but did not propagate onto it here we investigate the rupture dynamics of the haiti earthquake seeking to understand why rupture propagated across two segments of the leog ne fault but did not propagate to the adjacent enriquillo plantain garden fault the major 200 km long plate boundary fault cutting through southern haiti we use a finite element model to simulate propagation of rupture on the leog ne fault varying friction and background stress to determine the parameter set that best explains the observed earthquake sequence in particular the ground displacement the two slip patches inferred from finite fault inversions are explained by the successive rupture of two fault segments oriented favorably with respect to the rupture propagation while the geometry of the enriquillo fault did not allow shear stress to reach failure

slip rate and earthquake recurrence along the central septentrional fault north american caribbean plate boundary dominican republic 1 the septentrional fault zone sfz is the major north american caribbean strike slip plate boundary fault at the longitude of eastern hispaniola the sfz traverses the densely populated cibao valley of the dominican republic forming a prominent scarp in alluvium our studies at four sites along the central sfz are aimed at quantifying the late quaternary behavior of this structure to better understand the seismic hazard it represents for the northeastern caribbean our investigations of excavations at sites near rio cenovi show that the most recent ground rupturing earthquake along this fault in the north central dominican republic occurred between a d 1040 and a d 1230 and involved a minimum of 4 m of left lateral slip and 2 3 m of normal dip slip at that site our studies of offset stream terraces at two locations rio juan lopez and rio licey provide late holocene slip rate estimates of 6 9 mm yr and a maximum of 11 12 mm yr respectively across the septentrional fault combining these results gives a best estimate of 6 12 mm yr for the slip rate across the sfz three excavations two near tenares and one at the rio licey site yielded evidence for the occurrence of earlier prehistoric earthquakes dates of strata associated with the penultimate event suggest that it occurred post a d 30 giving a recurrence interval of 800 1200 years these studies indicate that the sfz has likely accumulated elastic strain sufficient to generate a major earthquake during the more than 800 years since it last slipped and should be considered likely to produce a destructive future earthquake

the caribbean plate pulled pushed or dragged 1 mechanical coupling between the lithosphere and the asthenosphere remains a controversial topic in the geosciences beneath the caribbean plate shear wave splitting measurements indicate ew strain in the asthenosphere which can be interpreted as mantle flow driving or resisting motion of the overlying lithosphere here we constrain the average shear traction on the base of the caribbean plate by balancing all torques these torques result from body forces that act on the caribbean slab pull ridge push lateral density variations from plate boundary friction and from basal shear tractions we obtain a range of physically realistic torque solutions which we examine further by computing the corresponding stresses and rotations within the caribbean plate for comparison with observations the deformation field for the caribbean is particularly sensitive to the amount of friction on intraplate faults representative models have a good fit with observations and are characterized by 1 a near zero basal shear traction 0 3 mpa 2 lithosphere averaged plate boundary friction 10 mpa 3 local forces due to indenters and trench pull 4 a net pull by the caribbean slab and 5 intraplate fault shear stresses on the order of tens of megapascals we conclude that the mechanical coupling of the caribbean plate to the underlying asthenosphere is small

crustal structure and fault geometry of the 2010 haiti earthquake from temporary seismometer deployments haiti has been the locus of a number of large and damaging historical earthquakes the recent 12 january 2010 mw 7 0 earthquake affected cities that were largely unprepared which resulted in tremendous losses it was initially assumed that the earthquake ruptured the enriquillo plantain garden fault epgf a major active structure in southern haiti known from geodetic measurements and its geomorphic expression to be capable of producing m 7 or larger earthquakes global positioning systems gps and interferometric synthetic aperture radar insar data however showed that the event ruptured a previously unmapped fault the leog ne fault a north dipping oblique transpressional fault located immediately north of the epgf following the earthquake several groups installed temporary seismic stations to record aftershocks including ocean bottom seismometers on either side of the epgf we use data from the complete set of stations deployed after the event on land and offshore to relocate all aftershocks from 10 february to 24 june 2010 determine a 1d regional crustal velocity model and calculate focal mechanisms the aftershock locations from the combined dataset clearly delineate the leog ne fault with a geometry close to that inferred from geodetic data its strike and dip closely agree with the global centroid moment tensor solution of the mainshock but with a steeper dip than inferred from previous finite fault inversions the aftershocks also delineate a structure with shallower southward dip offshore and to the west of the rupture zone which could indicate triggered seismicity on the offshore trois baies reverse fault we use first motion focal mechanisms to clarify the relationship of the fault geometry to the triggered aftershocks

is there a northern lesser antilles forearc block 1 a systematic discrepancy exists between slip vectors of thrust fault earthquakes at the lesser antilles trench lat and the predicted direction of north american caribbean convergence a possibility has been that the discrepancy resulted because neither was well constrained estimating caribbean motion has been challenging owing to the limited data along the plate s complex boundaries similarly earlier studies had few slip vectors because interplate thrust events are infrequent to address these difficulties we estimate a new caribbean north america euler vector using recently available gps data from sites in the presumably stable interior of the caribbean and compare the predicted velocities to a larger set of slip vectors the discrepancy persists suggesting the northern lesser antilles forearc nlaf moves as a distinct entity from both the caribbean and north america for simplicity we treat its motion as a coherent block but because gps sites are not within the nlaf distributed deformation is also possible although there is no geologic evidence for the boundaries of the presumed nlaf block gps data show that the motions of martinique barbados and trinidad are similar to that of the caribbean suggesting that none are on the nlaf block and the southern lat is weakly coupled

polyphase tectonic history of the southern peninsula haiti from folding and thrusting to transpressive strike slip abstract the southern peninsula of haiti is a seismically active east west trending transpressive mountain range with elevations over 2 km present day deformation is mainly partitioned along the left lateral enriquillo plantain garden fault zone epgfz and associated oblique reverse faults and or folds the configuration of these faults their respective timing and the role of structural heritage on their development is poorly understood to address these questions we present the results of extensive field campaigns combined with satellite imagery interpretation and published data which allows us to constrain the cenozoic evolution of the southern peninsula our results show a polyphase tectonic history consisting of three major tectonic events 1 maastrichtian to early paleocene crustal scale folding that developed coevally with predominantly north to northeast dipping thrusts resulting in uplift and erosion of the cretaceous sedimentary cover in large parts of the southern peninsula 2 early miocene uplift and erosion which was strongest in the southwestern part of the peninsula and decreased eastwards did not affect the massif de la selle uplift is most likely unrelated to strike slip activity but resulted from folding in response to ne sw shortening that possibly reactivated older predominantly n to ne dipping thrusts 3 late miocene to present day deformation and uplift spatially distributed strike slip started during the late miocene and became progressively focused along the epgfz in the latest miocene oblique and thrust faults locally post date strike slip activity from the pliocene onward increase in compressional deformation from west to east is reflected by a change in structural style with predominantly strike slip faults in the west and transpressional faults in the east the latter possibly rooted on the epgfz at depth paleo stresses associated with a strike slip regime are at a significantly high angle to the trace of the epgfz indicating that the epgfz is a mechanically weak fault

morphostructure at the junction between the beata ridge and the greater antilles island arc offshore hispaniola southern slope abstract oblique convergence between the caribbean plate s interior and the inactive greater antilles island arc has resulted in the collision and impingement of the thickened crust of the beata ridge into southern hispaniola island deformation resulting from this convergence changes from a low angle southward verging thrust south of eastern hispaniola to collision and uplift in south central hispaniola and to left lateral transpression along the southern peninsula of haiti in western hispaniola using new swath bathymetry and a dense seismic reflection grid we mapped the morphological structural and sedimentological elements of offshore southern hispaniola we have identified four morphotectonic provinces the dominican sub basin the muertos margin the beata ridge and the haiti sub basin the lower slope of the muertos margin is occupied by the active muertos thrust belt which includes several active out of sequence thrust faults that were they to rupture along their entire length could generate large magnitude earthquakes the interaction of the thrust belt with the beata ridge yields a huge recess and the imbricate system disappears the upper slope of the muertos margin shows thick slope deposits where the extensional tectonics and slumping processes predominate the northern beata ridge consists of an asymmetrically uplifted and faulted block of oceanic crust our results suggest that the shallower structure and morphology of the northern beata ridge can be mainly explained by a mechanism of extensional unloading from the upper cretaceous onward that is still active residually along the summit of the ridge the tectonic models for the northern beata ridge involving active reverse strike slip faults and transpression caused by the oblique convergence between the beata ridge and the island arc are not supported by the structural interpretation the eastern bahoruco slope an old normal fault that acts as a passive tear fault accommodating the sharp along strike transition from low angle thrusting to collision and uplifting

palaeoecology palaeogeography and depositional environments of upper cretaceous rocks of western venezuela abstract the end of the early cretaceous in northern south america was marked by regional palaeoceanographic change in western venezuela this change was highlighted near the end of the albian by drowning of the maraca formation shallow water carbonate platform regional marine transgression continued during the cenomanian and turonian in western venezuela with drowning of the more southerly guayacan member capacho and escandalosa formations carbonate platform deposition of organic carbon rich intervals of the la luna and navay formations occurred unconformably on maraca formation and guayacan member shallow water carbonates and continued through the early santonian during this interval the maracaibo and barinas apure basins were characterized by low oxygen or anoxic bottom water conditions away from the basin margins deposition of organic carbon lean upper la luna and navay formation strata show that bottom water oxygen content increased from the late santonian through the end of the cretaceous the siliceous and phosphatic late santonian to early maastrichtian tres esquinas member and the glauconitic late campanian to early maastrichtian socuy member both of the la luna formation represent the final phase of la luna deposition in the maracaibo basin tectonic uplift in eastern colombia during the campanian and maastrichtian caused progradation of the colon mito juan and burguita formation deltas and eventual infilling of the maracaibo and barinas apure basins

diachronous uplift and recycling of sedimentary basins during cenozoic tectonic transpression northeastern caribbean plate margin abstract four marine sedimentary sequences of late cretaceous to pleistocene age crop out in the 320 km long 1 to 30 km wide peralta rio ocoa belt of hispaniola haiti and dominican republic the four sedimentary sequences are dominated by marine turbiditic rocks ranging up to 11 5 km in apparent thickness and exhibit mainly northwest to southeast belt parallel paleocurrents the three younger sequences are generally in fault or unconformable contact with the underlying sequence from northwest to southeast the four belts become progressively wider younger less metamorphosed less folded and faulted and lower in topographic elevation we interpret the three younger sequences as a syn tectonic stratigraphic record of diachronous northwest to southeast transpressional closure of a coniacian danian back arc basin represented by the oldest exposed sedimentary sequence at the northwest end of the belt and inferred at depth beneath the three younger sequences using the stratigraphic record we infer the following three stages in the closure of the back arc basin and the overlying younger basins stage one latest cretaceous to early late eocene closure a minimum of 11 km of paleocene turbidites and limestone in the padre las casas area and a minimum of 11 5 km of early eocene to early late eocene pelagic limestone mudstone sandstone and siltstone in the peralta and sierra el numero areas was deposited in an elongate basin derived from the first stage of latest cretaceous early late eocene closure and erosion of the coniacian danian back arc basin to the northwest paleocene eocene turbidites in both areas contain large amounts of reworked campanian paleocene microfauna and exhibit northwest to southeast belt parallel paleocurrents syn deformational features in eocene sedimentary rocks in the peralta and sierra el numero area indicate that convergent deformation accompanied sedimentation witschard and dolan 1990 stage two middle eocene to early miocene closure up to 8 6 km of middle eocene to early miocene turbidites debris flows and olistostromes of the rio ocoa group of the dominican republic were deposited in an elongate basin derived from middle eocene to early miocene closure uplift and erosion of the peralta group to the west and northwest turbidites contain reworked eocene faunas and lithologies similar to those in the underlying peralta group and exhibit northwest to southeast belt parallel paleocurrents erosion of late cretaceous island arc and overlying paleogene carbonate rocks of the cordillera central provided additional belt perpendicular sources of coarser grained conglomerate and olistostromes following deposition of the rio ocoa group both the peralta and the rio ocoa group were deformed in a southwest verging fold and thrust belt during the early miocene stage three middle miocene to recent closure up to 1 5 km of middle miocene to pleistocene sandstone conglomerate and reefal limestone of the ingenio caei group of the dominican republic were deposited in an elongate basin above a pronounced angular unconformity developed on the older deformed rocks of the rio ocoa group sediments of the ingenio caei group were derived from middle miocene to recent closure uplift and erosion of the rio ocoa and peralta groups to the northwest onshore exposures of the ingenio caei group can be correlated with submerged strata seen on seismic reflection profiles across the offshore san pedro basin recent submarine clastic sedimentation in the san pedro basin is dominated by northwest to southeast influx of clastic turbidites derived from active erosion of onshore exposures of the rio ocoa and ingenio caei groups middle miocene to recent sediments of the san pedro basin are being actively shortened by northward to northeastward directed underthrusting along the muertos trench underthrusting at the muertos trench is suggested to represent ongoing closure of the back arc basin thought to be deeply buried beneath the san pedro basin tectonic transpression along the closing back arc basin marks one edge of an actively deforming microplate within the north america caribbean strike slip plate boundary zone

defining the translational velocity of the reference frame of earth summary earth s centre is fundamental to geodesy and geoscience because motions of sites on the surface are estimated relative to it international terrestrial reference frames itrf2000 and itrf2005 are defined by the centre of mass of earth s system cm consisting of solid earth the ice sheets the oceans and the atmosphere satellite lageos rotates about cm satellite laser ranging slr is used to estimate the velocity of cm relative to sites on the surface however itrf2000 and itrf2005 differ by 1 8 mm yr 1 suggesting that the velocity of cm is constrained poorly by slr in this study we define earth s reference frame with the centre of mass of solid earth ce site velocities estimated using slr vlbi gps and doris are corrected for a postglacial rebound model and inverted for the rotational velocities of the plates and the rotational and translational velocities of the four space techniques because the postglacial rebound predictions are relative to ce the velocity of ce relative to sites on the surface is estimated because the input slr site velocities are relative to cm the output slr translational velocity is the velocity of cm relative to ce the estimated velocity of ce does not depend strongly on the postglacial rebound model corrected for equal within uncertainties and having a root mean square of 0 5 mm yr 1 are estimates of the velocity of ce determined assuming that plate interiors are deforming radially as predicted by three postglacial rebound models and an estimate of the velocity of ce determined assuming that parts of plate interiors neither beneath nor along the margins of the late pleistocene ice sheets are not deforming laterally the velocity of ce equals within uncertainties probability greater than 5 per cent the velocity of cm in itrf2000 the velocity of ce differs significantly 0 05 per cent probability from the velocity of cm in itrf2005 earth s reference frame and we believe itrf s should be defined with the tightly constrained velocity of ce not with the poorly constrained velocity of cm because ce is believed to be moving relative to cm no faster than 0 5 mm yr 1 the velocity of ce estimated in this study is likely to be nearer the true velocity of cm than is the velocity of cm estimated using slr

submarine morpho structure and active processes along the north american caribbean plate boundary dominican republic sector abstract the northern margin of hispaniola records the oblique collision underthrusting of the bahamas carbonate province with the island arc due to the collision northern hispaniola has suffered several natural disasters caused by major earthquakes and tsunamis such as the historic earthquake of 1842 the tsunami caused by earthquake driven slumping in 1918 in the mona passage the seismic crisis of 1943 1953 with five events of m 7 0 or the seismic crisis of 2003 with a main shock of m6 3 and a large aftershock of m5 3 using new swath multibeam bathymetry data and vintage single and multi channel seismic profiles we have performed a regional scale analysis and interpretation of the shallow morpho structure and active processes along the northern margin of the dominican republic we have identified three morphostructural provinces a the bahamas carbonate province b the hispaniola trench and c the insular margin which are divided into two tectonic domains the collision domain and underthrusting domain the southern slope of the bahamas carbonate province shows a very irregular morphology produced by active erosive processes and normal dip slip faulting evidence of an extensional tectonic regime and margin collapse this collapse is of major extent in the oblique collision domain where there are erosive and fault escarpments with higher dip slip fault throws the hispaniola trench is formed by the caicos and hispaniola basins in the underthrusting domain and by the santisima trinidad and navidad basins in the oblique collision domain they have a flat seafloor with a sedimentary filling of variable thickness consisting of horizontal or sub horizontal turbiditic levels the turbiditic fill mostly proceeds from the island arc through wide channels and canyons which transports sediment from the shelf and upper slope the insular margin comprises the insular shelf and the insular slope the active processes are generated on the insular slope where the northern hispaniola deformed belt is developed this deformed belt shows a very irregular morphology with a wnw ese trending n verging imbricate thrust and fold system this system is the result of the adjustment of the oblique collision underthrusting between the north american plate and the caribbean plate in the oblique underthrusting domain the along strike development of the imbricate system is highly variable forming salients and recesses this variability is due to along strike changes in the sediment thickness of the hispaniola trench as well as to the variable topography of the underthrusting bahamas carbonate province in the oblique collision domain the morphology of the insular slope and the development of the deformed belt deeply change the imbricate system is barely inferred and lies upslope these changes are due to the active collision of bahamas carbonate province with the insular margin where the spurs are indented against the insular margin throughout the entire area studied gravitational instabilities have been observed especially on the insular margin and to a lesser extent on the southern slope of the bahamas carbonate province these instabilities are a direct consequence of the active underthrusting collision process we have mapped large individual slumps north of puerto plata in the oblique underthrusting domain and zones of major slumps in the oblique collision domain these evidences of active processes must be considered as near field sources in future studies on the assessment of tsunami hazards in the region

oblique collision in the northeastern caribbean from gps measurements and geological observations 1 previous caribbean gps studies have shown that the rigid interior of the caribbean plate is moving east northeastward 070 at a rate of 18 20 3 mm yr relative to north america this direction implies maximum oblique convergence between the island of hispaniola on the caribbean plate and the 22 27 km thick crust of the bahama carbonate platform on the adjacent north america plate we present a tectonic interpretation of a 15 site gps network which spans the hispaniola bahama oblique collision zone and includes stable plate interior sites on both the north america and caribbean plates measurements span the time period of 1994 1999 in a north america reference frame gps velocities in puerto rico st croix and the lesser antilles indicate that these areas move as a single block in an east northeast direction 070 at a rate of 19 20 mm yr consistent with the movement of the rigid interior of the caribbean plate gps velocities at six sites in central and eastern hispaniola dominican republic show drastically different behavior with more eastwardly strikes 080 and much slower rates 4 17 mm yr than areas of the stable caribbean plate the boundary between the relatively slower moving hispaniola collisional zone and the relatively faster moving uncollided puerto rico virgin islands area is the mona passage where late neogene rifting occurs in a broad zone elastic modeling favors strain partitioning with oblique slip on the outer low angle submarine thrust faults north hispaniola muertos and strike slip on the inner subvertical subaerial strike slip faults septentrional enriquillo

rapid exhumation of cretaceous arc rocks along the blue mountains restraining bend of the enriquillo plantain garden fault jamaica using thermochronometry from multiple closure systems abstract the effect of rapid erosion on kinematic partitioning along transpressional plate margins is not well understood particularly in highly erosive climates the blue mountains restraining bend bmrb of eastern jamaica bound to the south by the left lateral enriquillo plantain garden fault epgf offers an opportunity to test the effects of highly erosive climatic conditions on a 30 km wide restraining bend system no previous thermochronometric data exists in jamaica to describe the spatial or temporal pattern of rock uplift and how oblique 20 plate motion is partitioned into vertical strain to define the exhumation history we measured apatite n 10 and zircon n 6 u th he ages 40ar 39ar n 2 amphibole and k spar ages and u pb zircon n 2 crystallization ages late cretaceous u pb and 40ar 39ar ages 74 68 ma indicate rapid cooling following shallow emplacement of plutons during north south subduction along the great caribbean arc early to middle miocene zircon helium ages 19 14 ma along a vertical transect suggest exhumation and island emergence at 0 2 mm yr older zircon ages 10 15 km to the north 44 35 ma imply less rock uplift apatite helium ages are young 6 1 ma across the entire orogen suggesting rapid exhumation of the bmrb since the late miocene these constraints are consistent with previous reports of restraining bend formation and early emergence of eastern jamaica an age elevation relationship from a vertical transect implies an exhumation rate of 0 8 mm yr while calculated closure depths and thermal modeling suggests exhumation as rapid as 2 mm yr the rapid rock uplift rates in jamaica are comparable to the most intense transpressive zones worldwide despite the relatively slow 5 7 mm yr strike slip rate we hypothesize highly erosive conditions in jamaica enable a higher fraction of plate motion to be accommodated by vertical deformation thus strike slip restraining bends may evolve differently depending on erosivity and local climate

shallower structure and geomorphology of the southern puerto rico offshore margin oblique convergence between the north american and caribbean plates along the eastern greater antilles island arc has yielded the asymmetric muertos thrust belt in the backarc region offshore south of puerto rico this thrust belt disappears and is replaced by a succession of neesw and eew trending deep basins and steep ridges that characterize the western anegada passage resulting in a complex deformation pattern using new high resolution multibeam bathymetry and seismic reflection profiles we studied the geomorphology and shallower structure of the southern puerto rico offshore margin we have identified four morphotectonic provinces the puerto rican sub basin and muertos trough the muertos margin the insular shelf and the western anegada passage the muertos margin province shows two distinct slope sub provinces the active muertos thrust belt e which includes lower and upper thrust belts with distinct deformational styles and lateral continuity e and the shelf slope highly incised by a dense canyon network this network is disrupted by the investigator fault zone consisting of a 130 km long eew trending band of active extensional deformation the investigator fault zone shows differential surface expression caused by along strike changes in the magnitude and distribution of the deformation though this deformation is driven by a nes oriented extension in the western anegada passage province the whiting basin and whiting and grappler ridges are formed by large dip slip normal faults driven by a nwese oriented extensional regime the western st croix rise shows a complex structure where the neesw trending nw dipping normal faults observed at the summit of the rise predate the eew bounding faults that could accommodate the extensional deformation at the present this study provides detailed observations on the active tectonic and sedimentary processes to help future studies assessing the natural resources and the seismic and tsunamigenic hazard in the puerto rico region

active tectonics along the cul de sac enriquillo plain and seismic hazard for port au prince haiti abstract the active faults in haiti were not well known and no detailed mapping of active fault traces was available before the 2010 m7 0 earthquake the lack of detailed fault mapping hindered the interpretation of the event and the seismic hazard assessment here using high resolution lidar topography aerial photographs bathymetric charts together with geological data complemented with field observations we carried out a morphotectonic analysis at a variety of scales we analyzed the drainage network at the northern front of the massif de la selle sierra de bahoruco msb by mapping the fans of the main rivers and their associated drainage basins we found that the areas of all the fans were compatible with the sizes of their drainage basins except the paleofan of port au prince we interpret that this paleofan has been offset by 7 9 0 3 km across the main strike slip enriquillo plantain garden fault epgf and we estimate a minimum horizontal slip rate of 3 mm yr over the pleistocene moreover in the cul de sac enriquillo plain within which the capital city of port au prince is located we mapped numerous nw se to wnw ese striking quaternary folds and thrust faults some of the thrust faults are north dipping and located to the southern front of the matheux neiba lower miocene fold other thrusts such as those near ganthier jacquet nan cadastre and port au prince are south dipping and located along the northern front of the msb lower miocene fold previously saint fleur et al 2015 showed that the 2010 haiti earthquake activated both one of the young thrusts lamentin and the epgf consistent with oblique convergence between the caribbean and the north american plates

earthquake source parameters for the 2010 january haiti main shock and aftershock sequence summary previous analyses of geological and geodetic data suggest that the obliquely compressive relative motion across the caribbean north america plate boundary in hispaniola is accommodated through strain partitioning between near vertical transcurrent faults on land and low angle thrust faults offshore in the dominican republic earthquake focal mechanism geometries generally support this interpretation little information has been available about patterns of seismic strain release in haiti however due to the small numbers of moderate to large earthquakes occurring in western hispaniola during the modern instrumental era here we analyse the damaging mw 7 0 earthquake that occurred near port au prince on 2010 january 12 and aftershocks occurring in the four months following this event to obtain centroid moment tensor cmt solutions for 50 earthquakes with magnitudes as small as mw 4 0 while the 2010 january main shock exhibited primarily strike slip motion on a steeply dipping nodal plane strike 250 dip 71 and rake 22 we find that nearly all of the aftershocks show reverse faulting motion typically on high angle 30 45 nodal planes two small aftershocks mw 4 5 and 4 6 located very close to the main shock epicentre show strike slip faulting with geometries similar to the main shock one aftershock located off the south coast of haiti shows low angle thrust faulting we also examine earthquakes occurring in this region from 1977 2009 successful analysis of four such events provides evidence for both strike slip and reverse faulting the pattern of seismic strain release in southern haiti thus indicates that partitioning of plate motion between transcurrent and reverse structures extends far west within hispaniola while we see limited evidence for low angle underthrusting offshore most reverse motion appears to occur on high angle fault structures adjacent to the enriquillo fault our results highlight the need to incorporate seismogenic slip on compressional structures into hazard assessments for southern haiti

deformation of jamaica and motion of the gonâve microplate from gps and seismic data summary we use velocities from 20 gps sites on the island of jamaica and seismic data from the jamaican seismic network to quantify motion of the proposed gonave microplate and study deformation and earthquake hazard in jamaica all 20 jamaican gps sites move significantly relative to both the caribbean and north american plates thereby confirming the existence of the gonave microplate in a caribbean plate reference frame the fastest site velocities in jamaica are 8 1m m yr 1 representing a minimum estimate for the rate of gonave caribbean plate motion we estimate a firm upper limit of 13 1m m yr 1 for gonave caribbean plate motion assuming that additional elastic or permanent deformation occurs north of jamaica beyond the reach of our gps network the range of estimates for gonave caribbean plate motion exceeds the 3 7m m yr 1 range of geologically derived rates for post 10 ma fault slip in jamaica suggesting that motion has either increased relative to the long term deformation rate or that estimates of the long term deformation rate are too slow minimum and maximum rates for gonave north america plate motion are 6 1m m yr 1 and 11 1m m yr 1 based on the differences between the estimated gonave caribbean rates and a recent gps based estimate of 19 3 1m m yr 1 of caribbean north american plate motion in jamaica these are slower than 15 20 mm yr 1 published estimates of the long term seafloor spreading rate across the cayman spreading centre which records gonave north american plate motion our observations are thus consistent with a model in which gonave caribbean plate motion has increased through time while gonave north america plate motion has decreased possibly reflecting a progressive transfer of slip from plate boundary structures that accommodate gonave north america motion to faults that carry gonave caribbean plate motion in jamaica gps site directions in both the caribbean and north american plate reference frames are parallel to the caribbean north america plate slip direction and are only 10 20 different from the azimuths of the island s major strike slip faults the mean p and t axes for 48 earthquakes since 1941 have near horizontal plunges and are oriented 45 from the predicted plate slip direction the kinematic and seismic data thus indicate that deformation on the island is dominated by left lateral shear along largely e w trending strike slip faults relative to the caribbean plate the jamaican gps velocities exhibit a nearly monotonic increase in site velocities from south to north along a transect orthogonal to the island s major e w faults this velocity gradient likely reflects the accumulation of elastic strain due to frictional locking of the major e w faults velocities however also increase monotonically from the wsw to ene along a transect orthogonal to the island s numerous nnw striking faults consistent with the accumulation of significant elastic shortening along those faults and supportive of an interpretation of those faults as restraining bends seismic hazard assessment based on the gps derived deformation budget likely maximum fault rupture lengths and the historical seismic record suggests approximate repeat times of one to several centuries for earthquakes of maximum magnitudes of m w 7 0 7 3 the strain that has accumulated since the destructive 1692 earthquake near the capital city of kingston is presently sufficient to release a m w 7 2 earthquake in eastern jamaica

strain partitioning and fault slip rates in the northeastern caribbean from gps measurements 1 gps data collected in the dominican republic from 1994 to 2001 show that oblique convergence between the north american and caribbean plates is partitioned between 5 2 2 mm yr 1 of dip slip reverse motion on the north hispaniola thrust approximately n s and 12 8 2 5 mm yr 1 and 9 0 9 0 mm yr 1 of approximately e w left lateral strike slip motion on the septentrional and enriquillo faults 95 confidence the agreement between gps and paleoseimological slip rates on the septentrional fault together with the 770 960 years since the last major earthquake and the 800 1200 years maximum repeat time of major earthquakes may indicate that the septentrional fault is currently in the late phase of its rupture cycle

coseismic slip distribution of the 2010 m 7 0 haiti earthquake and resulting stress changes on regional faults the 12 january 2010 mw 7 0 haiti earthquake ruptured the previously unmapped leog ne fault a secondary transpressional structure located close to the enriquillo fault the major fault system assumed to be the primary source of seismic hazard for southern haiti in the absence of a precise aftershock catalog previous estimations of coseismic slip had to infer the rupture geometry from geodetic and or seismological data here we use a catalog of precisely relocated aftershocks begin ning one month after the event and covering the following 5 months to constrain the rupture geometry estimate a slip distribution from an inversion of global positional systems gps interferometric synthetic aperture radar insar and coastal uplift data and calculate the resulting changes of coulomb failure stress on neighboring faults the relocated aftershocks confirm a north dipping structure consistent with the leog ne fault as inferred from previous slip inversions but with two subfaults each corresponding to a major slip patch the rupture increased coulomb stresses on the shallow enriquillo fault parallel to the leog ne rupture surface and to the west mirago ne area and east port au prince results show that the cluster of reverse faulting earthquakes observed further to the west coincident with the offshore trois baies fault are triggered by an increase in coulomb stress other major regional faults did not experience a significant change in stress the increase of stress on faults such as the enriquillo are a concern as this could advance the timing of future events on this fault still capable of magnitude 7 or greater earthquakes online material figures showing observed and calculated insar ranges for

organic matter geochemistry and petrography of late cretaceous cenomanian turonian organic rich shales from the belle fourche and second white specks formations west central alberta canada abstract organic rich mudstones with up to 10 wt toc from the upper portion of the belle fourche formation and the lower part of the second white specks formation in the western canada sedimentary basin were evaluated as source rocks both geochemistry and organic petrography indicate an open marine paleoenvironment with deposition of type ii kerogen based on the predominance of marine alginite and amorphous organic matter om limited amounts of terrigenous vitrinite and inertinite macerals the presence of marine fossils and the low ratio of toc to total sulfur 1 26 the prevalence of short chain n alkanes n c13 to n c19 a predominance of c28 h 20s steranes and small concentrations of oleanane confirm the dominantly algal and planktonic origin of om alternating oxic to anoxic paleoenvironmental sedimentary conditions are proposed based on common bioturbation abundant inoceramid prisms and good organic richness biomarker distributions are consistent with intermittent anoxia without unequivocal evidence for water column stratification or hypersalinity the thermal maturity measured in seven sediment cores by different methods consistently indicates a westward increase in maturity according to vitrinite reflectance tmax and hopane and sterane biomarkers two cores are thermally immature 0 42 ro one is early mature 0 65 ro and four cores are within the oil window 0 78 to 0 89 ro all thermally mature cores retain good to very good hydrocarbon potential 248 mg hc g rock and are dominantly oil prone and minor gas prone based on their maceral compositions the upper belle fourche and lower second white specks formations represent potential targets for unconventional light shale oil production

seismic structure of the crust in the western dominican republic abstract the contact between the caribbean and north american plates is a tectonically complicated boundary where the deformation is accommodated in north and south of hispaniola by the enriquillo plantain garden and septentrional oriente fault zones epgfz and sofz we present a crustal and tectonic study of the northeastern caribbean plate boundary from wide angle seismic data was acquired during the geoprico do 2005 and caribe norte 2009 surveys showing two transects crossing from north to south north american plate noam bahamas platform central hispaniola and caribbean plate cp the results presented include two 2 d p wave velocity models of 425 km and 200 km long oriented nne ssw and ene ssw respectively obtained by the travel time forward and inverse modeling of the was data our study defines that the contact between bahamas platform north american plate and hispaniola corresponds to oblique subduction with the moho dipping 11 in the nne ssw direction furthermore in the south our results reveal the existence of an anomalous deep reaching zone of lateral velocity variation in the mantle that could be associated with epgfz and a possible detached oceanic slab from noam that could explain the deep seismicity in the region

seasonal variations in the upper arctic ocean as observed at t 3 hydrographic data from t 3 are analyzed to illustrate the behavior of the arctic mixed layer the mixed layer depth fluctuates 11 m annually and mixed layer salinity fluctuates 0 32 the fluctuations in total salt content are consistent with theoretical work by maykut and are in phase with mixed layer depth indicating changes in the mixed layer are controlled by salt flux deepening of the mixed layer brings 0 3 kcal cm 2 yr 1 of heat to the surface from the ocean below

gps constraints on deformation in northern central america from 1999 to 2017 part 2 block rotations and fault slip rates fault locking and distributed deformation

plate boundary readjustment in oblique convergence example of the neogene of hispaniola greater antilles the haitian fold and thrust belt is the major mountain belt of haiti western part of hispaniola greater antilles and resembles a compressive restraining bend between the two major faults which have driven the opening of the cayman basin since the eocene during the rifting stage from the middle to the late eocene this area underwent an extensional evolution with fissural volcanic activity along ne sw tilted blocks the haitian fold and thrust belt was constructed from the early miocene until the present by stacking sedimentary units into a collisional wedge perpendicular to the tilted blocks which was propagating to the southwest during the construction of the wedge piggyback basins were formed and progressively uplifted during the late neogene convergence is localized in the cul de sac enriquillo trough where the active front proceeds southward onto the beata ridge in this area miocene to quaternary wrench structures of the lower plate like the southern peninsula and the enriquillo plantain garden faults are reactivated as normal faults owing to the loading of the fold and thrust belt

calcite twinning strains from syn faulting calcite gouge small offset strike slip normal and thrust faults we have evaluated the stress strain behavior of calcite precipitated and mechanically twinned in small offset strike slip normal and thrust faults of a variety of ages and from a variety of tectonic settings n 3001 twin measurements 63 strain analyses from 18 field sites five strike slip faults with syn faulting horizontally striated calcite rake 0 were studied and we report the orientations of the contemporaneous stress strain field associated with each fault intrusion of the marathon large igneous province mafic dikes 2 1 ga in archean crust minnesota usa post keweenaw rift 1 1 ga faulting island lake fault central ontario canada subduction associated with metamorphic core complex formation cretaceous china subduction cretaceous to miocene italy and continental extension recently active furnace creek fault death valley california usa seven normal faults with synfaulting dip slip striated calcite were studied and are from the following tectonic settings a normal fault slip surface in an ordovician piedmont fold appalachian s paleo subduction associated with cretaceous metamorphic core complex formation china 3 sites the paleo extensional atlantic margin 55 ma ireland 1 site with a u pb calcite age continental extension 1 active site mojave desert a transcurrent margin jamaica 1 active fault site and subduction 2 active faults along the eur african margin in italy with calcite u th disequilibria ages and crete respectively six thrust fault examples are all from convergent orogenic settings the basal thrust of the penokean 1850 ma fold and thrust belt the penokean orogen foreland in mesabi range banded iron formation folds an offset breccia body in the permian gondwanide belt ellsworth mountains antarctica the frontal thrust of the gondwanide cape belt south africa the paleocene frontal prospect thrust sevier belt wyoming and an alpine foreland back thrust lulworth cove u k for each strike slip fault system the twinning shortening strain is horizontal and at an angle of 0 60 to the respective fault plane dextral or sinistral although in the majority of cases the shortening axis is parallel to fault strike 13 of 23 results in each normal fault example dip slip kinematic striations dominate the faulted surface yet the orientation of the maximum principal compressive stress 1 and shortening strain axis e1 are not 45 to the fault plane as predicted but are sub horizontal and either strike parallel 25 of 35 results or strike normal 10 of 35 results thrust faults preserve shortening strain axes parallel to the dip slip kinematic direction within the fault plane plane strain and not at 45 to the principal plane 5 of 5 results none of the fault stress strain field results reported here support the andersonian or mohr coulomb criteria for stress strain relations predicted along faults

global basin classification system a proposed system classifies sedimentary basins worldwide into specific as well as general categories the geologic history of each basin may be subdivided into cycles using three parameters basin forming tectonics depositional sequences and basin modifying tectonics sedimentary basins may be simple with one or two tectonic sedimentary cycles or they may be complex polyhistory basins with many different cycles and events there are eight simple cycle types in this classification which cover continental continental margin and oceanic areas the eight basic cycle types their depositional fills and tectonic modifiers have been given letter and number symbols so that the specific geologic history of each basin may be written as a formula these formulas may then e compared and similarities or differences between basins noted

neotectonics of puerto rico and the virgin islands northeastern caribbean from gps geodesy the boundary between the north american and caribbean plates is characterized primarily by left lateral motion along predominantly east west striking faults seismicity and marine geophysical survey data are consistent with at least two and possibly three microplates in the diffuse boundary zone in the northeastern caribbean 1 the gonave 2 the hispaniola and 3 the puerto rico northern virgin islands prvi we discuss results from gps geodetic measurements acquired since 1994 to test the microplate hypothesis define prvi translation and rotation within the boundary zone and constrain prvi neotectonics gps derived velocities are analyzed with respect to both north american and caribbean plate reference frames integrated displacements across prvi are limited to a few millimeters per year consistent with a rigid prvi and permitting calculation of an average velocity for prvi the motions of prvi relative to north america and the caribbean are 16 9 1 1 mm yr toward n68 e 3 1 and 2 4 1 4 mm yr toward s79 w 26 1 respectively in contrast with some recent models ongoing rotation of prvi about a nearby 25 distant vertical axis is not supported by the geodetic data in addition we argue against eastward tectonic escape of prvi and favor a simple progressive increase in velocity across the plate boundary zone requiring that the summed magnitude of strike slip fault slip rates will equal the total plate motion rate between the caribbean and north america gps data are consistent with components of left lateral strike slip faulting along the muertos trough south of puerto rico and shortening across the puerto rico trench comparison of gps velocities for prvi with respect to north america with total north america caribbean relative motion suggests up to 85 of north american caribbean plate motion is accommodated by the puerto rico trench and offshore faults north of puerto rico differences in gps derived velocities from hispaniola and prvi yield east west extension across the n s trending mona rift of a few millimeters per year when estimated elastic strain accumulation effects along the north hispaniola deformed belt and the septentrional fault zone are considered the opening rate implies an age of the mona rift of 2 3 million years agreeing with marine geophysical data that support a young age for the structure

the neotectonic setting of puerto rico the island of puerto rico in the northeast caribbean lies within a broad deformation zone between the caribbean and north american plates the simplest model for the tectonic setting of puerto rico has major strike slip movement on nearly east west lines in the vicinity of the puerto rico trench coupled to a small counterclockwise rotation of a puerto rico block within the broader plate boundary zone this simple model is attractive because it predicts the tectonic regime south of puerto rico and provides an explanation for a possible component of extension across the puerto rico trench west of 65 5 w gloria long range sidescan sonar data and seismic reflection profiles have been used to test this model by mapping the major tectonic features across the plate boundary north and south of puerto rico to the north the new data help to resolve between conflicting models of underthrusting or strike slip motion at the puerto rico trench no direct evidence of compression is seen although evidence for normal and strike slip movement is abundant this combined with regional considerations leads us to conclude that the main east west trending part of the puerto rico trench between 65 5 w and 68 w lies within a strike slip regime although oblique convergence occurs both to the east and west where the plate boundary trends east southeast to the south of puerto rico underthrusting of the caribbean plate beneath the island decreases from west to east and it is ultimately replaced by extension in the virgin islands basin east of 65 w