wintertime winds and coastal sea level fluctuations in the northeast china sea part ii numerical model abstract as a sequel to data analysis reported in part i a numerical model of the wintertime wind driven circulation of the northeast chine sea is developed with the primary purpose of achieving an understanding of the underlying dynamics to several observed features of the coastal sea level behavior the model is linear and pertains to the vertically integrated balance of momentum and mass in a well mixed shallow ocean the model bathymetry incorporates a realistic shelf embayment and an open ocean region of a depth so limited that observed sea level differences across open boundaries in the deep western pacific do not result in unreasonably large model transports from results of model runs for the 1980 81 winter it is found that 1 along the west coast of south korea sea level setup to the south is a consequence chiefly of the presence at the end of the korean peninsula of relatively deep offshore water that is less responsive to wind forcing than the shallow shelf water 2 pressure gradient forc

recent current observations in the eastern yellow sea observations of current velocity pressure and temperature in the eastern yellow sea from january 10 through april 12 1986 together with geostrophic winds calculated from surface atmospheric pressure distributions are analyzed for a study of the synoptic band response of the yellow sea to the wintertime winds north wind pulses in the winter monsoon are found to give rise to northward flow bursts in the yellow sea trough which appear to peak just as the wind relaxes and to be driven by a synoptic band north to south rise in bottom pressure synchronous with the north wind pulses the existence of a similar rise in coastal sea level indicates that the observed southward pressure rise is but an offshore extension of a setup along the west coast of south korea forced by the north wind pulses the advection by northward flow bursts of warm water from the south apparently causes the measured temperature to be substantially higher in the trough than in coastal waters at the same latitude and the observed rate of cooling in the trough to be less than half of that in coastal waters to the east a winter to spring transition is also found in the bottom pressure records obtained in the trough in which the mean north to south gradient in winter reverses suddenly in early march a similar reversal also appears in sea level records along the west coast of south korea the reversal appears to be triggered by the weakening of the north winds at the arrival of spring

coastal wave generation in the bohai bay and propagation along the chinese coast the bohai bay and yellow sea experience sea surface height ssh changes of 20 cm and larger during wintertime northerly and southerly wind bursts that have a time scale of a few days these large ssh changes give rise to coastal shelf waves that subsequently propagate southward along the chinese coast two models provide observations of these waves the first one is a statistical model based on four years of topex poseidon t p altimeter ssh observations and navy operational global atmospheric prediction system nogaps wind stress fields the second model is a numerical model forced by the wind stress the numerical model provides an objective interpretation of the wind stress response based on dynamical equations the statistical model is based on observations with a linear response to the wind forcing and thus complements the numerical model the observed waves closely resemble gravest mode shelf waves derived by analytical solutions

current observations on the development of the yellow sea warm current historically the climatological mean northward flow in the yellow sea trough has been referred to as the yellow sea warm current yswc since it was thought to originate as a branch of the tsushima current which transports warm kuroshio waters however the tsushima current does not penetrate into the yellow sea interior during winter the onset of what is referred to as the yswc during winter is directly observed using measurements of current profiles pressure and temperature and a wind climatology for the time period july 1995 through january 1996 the yswc is a result of weak southerly winds during summer during fall transition and winter monsoon periods strong northerly wind bursts drive a north to south rise in pressure extending from the trough over to the korean coast and force a northward flow in the yellow sea trough the rise in pressure and corresponding north wind forced yswc begin at the end of october for this measurement period and are observed into january these measurements show that the yswc has different seasonal forcing mechanisms direct current measurements are also presented which suggest a current flow north of cheju sometimes referred to as the cheju warm current

hydrocode simulation of the chicxulub impact event and the production of climatically active gases we constructed a numerical model of the chicxulub impact event using the chart d squared csq code coupled with the analytic equation of state aneos package in the simulations we utilized a target stratigraphy based on borehole data and employed newly developed equations of state for the materials that are believed to play a crucial role in the impact related extinction hypothesis carbonates calcite and evaporites anhydrite simulations explored the effects of different projectile sizes 10 to 30 km in diameter and porosity 0 to 50 the effect of impact speed is addressed by doing simulations of asteroid impacts vi 20 km s and comet impacts vi 50 km s the masses of climatically important species injected into the upper atmosphere by the impact increase with the energy of the impact event ranging from 350 to 3500 gt for co2 from 40 to 560 gt for s and from 200 to 1400 gt for water vapor while our results are in good agreement with those of ivanov et al 1996 our estimated co2 production is 1 to 2 orders of magnitude lower than the results of takata and ahrens 1994 indicating that the impact event enhanced the end cretaceous atmospheric co2 inventory by at most 40 consequently sulfur may have been the most important climatically active gas injected into the stratosphere the amount of s released by the impact is several orders of magnitude higher than any known volcanic eruption and with h2o is high enough to produce a sudden and significant perturbation of earth s climate

fireball passes and nothing burns the role of thermal radiation in the cretaceous tertiary event evidence from the charcoal record of north america high soot contents have been reported in cretaceous tertiary k t sedimentary rocks leading to the suggestion that the amount of thermal power delivered from the chicxulub impact was sufficient to have ignited wildfires soot cannot be used to indicate fire location however as soot from one large fire could spread globally sources other than biomass burning could also yield soot charcoal in nonmarine sedimentary rocks here quantified in situ in polished blocks provides a unique tool to record the distribution of wildfires and therefore assess the extent of any thermal radiation associated with the impact at chicxulub the k t and lowermost tertiary sedimentary rocks of six nonmarine sequences colorado to saskatchewan contain no charcoal or below background levels of charcoal and a significant quantity of noncharred organic materials revealing that there was no distinctive wildfire across the north american continent related to the k t event this finding indicates that the k t impact cannot have delivered a peak irradiance of 95 kw m 2 of thermal power to the atmosphere and 19 kw m 2 to the ground therefore the thermal power delivered from the impact to north america did not have the destructive potential previously predicted high amounts of thermal radiation were not responsible for the environmental perturbations or extinctions associated with the k t event

an asymmetric upwind flow yellow sea warm current 2 arrested topographic waves in response to the northwesterly wind 1 a warm and salty water mass exists along the yellow sea trough yst in winter this oceanic water mass is distinct from the ambient shelf water and is distributed on the western side of the yst it has long been reasoned that a yellow sea warm current yswc must exist a recent observational study indeed supports the existence of the yswc and shows that its position moved progressively westward as the warm water intrudes further shoreward toward the northwest in this paper we explain mechanisms for sustaining the yswc and for its westward displacement the northwesterly monsoonal wind prevails in the winter and is directed against the yswc the cross trough scale is small compared with the spatial scale of monsoonal variation so one can assume to the first order that the wind stress is uniform across the trough the curl of depth averaged wind stress has opposite signs on the two sides of the trough consequently two oppositely rotating gyres develop initially and they converge along the trough giving rise to a barotropic upwind flow but this upwind flow lasts only for a few days as the two gyres evolve and propagate as topographic waves for a northerly wind both gyres move westward since the positive negative potential vorticity flux on the western eastern side of the trough pushes the water toward shore trough if the bottom friction is negligible the steady response becomes a large anticyclonic gyre over the trough and the upwind current is squeezed toward the shore line in this case no yswc is sustained along or near the trough this runaway warm current can be arrested by a moderate bottom friction we therefore propose that the yswc is actually arrested topographic waves in response to local wind stress forcing

deep water clastic systems in the upper carboniferous upper mississippian lower pennsylvanian shannon basin western ireland the upper carboniferous shannon basin of western ireland contains a more than 2300 m thick 7540 ft basin fill succession shallowing upward from deep water to deltaic and incised fluvial deposits the deep water basin floor and slope succession is world renowned as an analog for hydrocarbon bearing deep water sandstones on several continental margins such as the basins in east and west africa south america the gulf of mexico and not least offshore northwest europe the shannon basin is frequently visited by both academia and industry for research and training purposes a series of behind outcrop research boreholes reveals the subsurface expression of the deep water rocks and is complemented by seismic scale cliff exposures the succession is interpreted as a first order basin scale linked sedimentary system this system can be analyzed using the principles of source to sink analysis and leaves the visitor with a complete picture of the basin fill enhanced by spectacular sedimentological and stratigraphic detail

wintertime winds and coastal sea level fluctuations in the northeast china sea part i observations abstract analyses of low pass filtered coastal sea level data and geostrophic winds derived from surface pressure charts for the period of 1 december 1980 through 31 march 1981 indicate that the wintertime dynamics in the northeast china sea is strongly influenced by the passage of rapidly moving cold fronts from northwest to southeast across the region along the west coast of korea sea level fluctuations are highly coherent with the north south wind in two bands centered respectively at about 0 17 and 0 36 cpd and propagate to the south for the low frequency band removal of the wind forced component of the sea level signal yields freely propagating fluctuations in bands centered at about 0 20 0 34 and 0 50 cpd that travel northward at approximately the phase speed expected for barotropic kelvin waves indicative of a relaxation in the sea level field following the successive passages of cold fronts coherence studies of winds and sea level differences in the tsushima strait indicate a correlation

occurrence of large temperature inversion in the thermohaline frontal zone at the yellow sea entrance in winter and its relation to advection temperature inversion higher temperature at a deeper depth in winter and its relation to advection were investigated by analyzing both conductivity temperature depth data in the southern yellow sea ys and northwestern east china sea during the winter of 2002 2003 and time series data of temperature salinity and currents at a buoy station at the ys entrance significant temperature inversions occur predominantly along the thermohaline front at the ys entrance where the cheju warm current water cwcw and the cold coastal waters meet in february 2003 on the northern frontal zone along 34 n where isotherms and isohalines declined downward to the north particularly large inversions with temperature differences of larger than 2 0 c were observed to occur more in troughs than in the crests of the wave like frontal meander where the cold korean coastal water kcw advances farther southward the inversion persisted until mid april at the buoy station in the frontal zone and both temperature and salinity showed simultaneous variations in the same manner during episodic occurrences of large inversions temperature and salinity decreased sharply in the upper layer but increased concurrently in the lower layer these episodic inversions were found to be closely related to the westward advection of the kcw in the upper layer and the northward advection of the cwcw in the lower layer it is considered that these advections may play an important role in maintaining baroclinicity in the northern frontal zone which is responsible for driving the westward transversal flow across the ys entrance

loop current and deep eddies abstract in contrast to the loop current and rings much less is known about deep eddies deeper than 1000 m of the gulf of mexico in this paper results from a high resolution numerical model of the gulf are analyzed to explain their origin and how they excite topographic rossby waves trws that disperse energy to the northern slopes of the gulf it is shown that north of campeche bank is a fertile ground for the growth of deep cyclones by baroclinic instability of the loop current the cyclones have horizontal vertical scales of about 100 km 1000 2000 m and swirl speeds 0 3 m s 1 the subsequent development of these cyclones consists of two modes a and b mode a cyclones evolve into the relatively well known frontal eddies that propagate around the loop current mode a cyclone can amplify off the west florida slope and cause the loop current to develop a neck that sometimes leads to shedding of a ring this process is shown to be the loop current s dominant mode of upper to deep variability

diagenetic alteration of the structure and δ18o signature of palaeozoic fish and conodont apatite potential use for corrected isotope signatures in palaeoenvironmental interpretation abstract the oxygen isotopic compositions of carboniferous conodonts and fish microfossils ichthyoliths from identical samples were analysed in tandem in order to test whether these phosphatic media can be reliably used for palaeoclimatic reconstruction the structure of conodonts and of most ichthyoliths analysed are somewhat analogous to the enamel and dentine bone tissue respectively of modern mammals therefore the diagenetic susceptibilities of the taxa analysed may provide important clues to other palaeoclimatic studies utilising a variety of biogenic apatite thermal maturation indices and scanning electron microscopy were used to characterise the preservation of biogenic apatite despite a high conodont colour alteration index cai of 5 5 conodont elements appear to have been only mildly affected by diagenetic alteration in contrast ichthyoliths were commonly recrystallised and exhibited diagenetic apatitic overgrowths containing amorphous pyrolytic carbon interpreted as indicating that at least some overgrowth material derived from the original biogenic apatite diagenetic alteration has resulted in ichthyolith 18 o values being systematically lower by on average 2 9 1 0 3 relative to conodont apatite conodont samples yielded regionally correlatable isotope values which can be interpreted in terms of more palaeoenvironmentally sensible palaeotemperatures relative to ichthyolith values densely crystalline enamel like conodont elements are interpreted as the more robust phosphatic medium to preserve original isotopic compositions the strong correlation r 0 8 of the 18 o values of the more structurally pristine conodont and commonly recrystallised ichthyolith apatite indicates that i despite diagenetic lowering of absolute isotope values original palaeoenvironmental records may be preserved and ii diagenetic overprinting may result in a stable offset and therefore be correctable locally

sea surface height variations in the yellow and east china seas 1 linear response to local wind stress the sea surface height ssh variations observed by the topex poseidon satellite in the yellow and east china seas are examined over the 3 years from 1993 through 1995 assuming a linear response to wind stress across the region the transfer function relating wind stress to ssh is modeled by a series of increasingly complex functions that gradually allow wind stress over successively broader regions and time periods to influence the ssh solution at a particular point the ssh response to instantaneous wind stress at the same point in space implies an ekman transport but the response explains only a small fraction of the ssh variability relating ssh to wind stress averaged over two subregions and including both instantaneous and 12 hour lagged wind stress indicates that a significant portion of ssh variability responds to winds that are remote in both space and time an optimal estimation of the transfer function by minimizing the error variance leads to an extended empirical orthogonal function eeof analysis of the wind stress field the ssh response to each wind mode is determined the analysis shows the principle variations in the wind stress to consist of northerly wind bursts during winter which produce large ssh drops in the bohai bay and northern yellow sea region the principal wind mode also is significantly related to variations along the shelf break near the kuroshio current the third and fourth wind stress modes indicate the passage of typhoons

propagation of kuroshio extension meanders between 143 and 149 e a two dimensional array of current and pressure recording inverted echo sounders provided synoptic measurements of the upper and deep fluctuations in the kuroshio extension between 1438 and 1498e with mesoscale resolution downstream propagating meanders with periods of 3 60 days were always present between june 2004 and september 2005 propagation speeds were estimated by two methods spectral analysis of path displacements and complex empirical orthogonal functions ceof analysis of along path anomalies the two methods produced similar results phase speeds increased smoothly from 10 km day 21 0 12 m s 21 for meanders with wavelengths and periods l t 5 420 km 40 days to 35 km day 21 0 41 m s 21 for l t 5 220 km 6 days meanders this empirically derived dispersion relationship is indistinguishable from that obtained for gulf stream meanders downstream of cape hatteras the deep ocean was populated with remotely generated upstream propagating eddies composed of a nearly depthindependent current structure upper meandersand deep eddies jointly spun up when they encountered each other with the deep eddy offset about a quarter wavelengthahead of the upper meander subsequently as the upper and deep features moved past each other and the vertical offset changed intensification ceased

fluid inclusion technique for determining maximum temperature in calcite and its comparison to the vitrinite reflectance geothermometer theory laboratory experiments and empirical observation suggest that many aqueous fluid inclusions in calcite reequilibrate during overheating and therefore some homogenization temperatures t h record a temperature close to the maximum reached by the rock this characteristic suggests that aqueous fluid inclusions in calcite can be used to establish maximum temperature t peak to test this hypothesis we have compiled fluid inclusion t peak mean random vitrinite reflectance r m and present day t peak from 46 diverse geologic systems that have been at t peak from 10 4 to 10 6 yr present t peak ranged from 65 to 345 c t h modes and means ranged from 59 to 350 c and r m data ranged from 0 4 to 4 6 spanning the temperature and thermal maturity range associated with burial diagenesis hydrothermal alteration and low grade metamorphism plots of t h and t peak data for systems thought to be currently at maximum temperature demonstrate close agreement between t h and present t peak in sedimentary basins although caution should be applied the relation suggests that t h of aqueous fluid inclusions in calcite may be a useful measure of maximum temperature this study also compares t h to mean random vitrinite reflectance r m to offer further support for the use of t h as a measure of t peak and to provide a better understanding of r m t h correlates well with r m and results in a curve similar to r m vs t peak calibrations determined by other workers the strong correlation correlation coefficient r 0 93 between t peak and r m in these systems suggests that maximum temperature is the major control on thermal maturation

westward shift of the yellow sea warm salty tongue 1 the accumulated in situ hydrographic survey as well as the satellite observed sea surface temperature sst show consistent westward shifting of the yellow sea warm salty tongue yswst in winter a 2 d thermal model is used to show the westward shifting of the yswst due to cooling and advection the mitgcm is applied to simulate the circulation in the yellow and east china seas under the northern monsoon wind in winter the sea surface height ssh is adjusted to have a ridge in the channel and a trough in the 50 70 m iso bath in the yellow sea the barotropic transport of ssh and baroclinic transport of horizontal density gradient play the major role for the shifting of the yswst while the ekman wind drift plays a minor role

organic maturation levels thermal history and hydrocarbon source rock potential of the namurian rocks of the clare basin ireland abstract vitrinite reflectance data from two inland cored boreholes confirm high maturation levels throughout the onshore part of the irish clare basin and suggest erosion of 2 to 4 km of late carboniferous cover and elevated palaeogeothermal gradients in the carboniferous section the observed maturation gradients are fully consistent with the published hypothesis of a late carboniferous permian superplume beneath pangaea but local vertical reversals in gradients also suggest a complex thermal regime probably involving advective heating the uppermost visean lower namurian clare shale is laterally extensive and up to 300 m thick although this unit is post mature toc values of up to 15 suggest that it could have considerable hydrocarbon source rock potential in any less mature offshore parts of the basin

a numerical study of currents heat advection and sea level fluctuations in the yellow sea in winter 1986 abstract a vertically integrated model that incorporates horizontal temperature variations is used to study the circulation of the yellow sea in a wintertime period for which velocity and temperature measurements are available at several moorings locations along a central trough the model features realistic bottom topography and is forced with wind stress and heat flux fields from 13 january to 22 february 1986 the model also incorporates as a boundary condition sea level fluctuations derived from coastal and insular tide gauge stations along model boundaries in open waters the model reproduces well sea level fluctuations along the coasts of both china and korea the hindcast velocity time series particularly for the north south component track those obtained from direct measurements at the moorings the model momentum balance indicates that the northward flow in the trough is driven by a sea level setup to the south in response to northerly wind bursts in the winter monsoon the sea level fluctuat

shock induced devolatilization of calcite the amounts of co 2 and co evolved upon shock compression and decompression of calcite to 18 gpa 180 kbar have been determined using a new gas phase shock recovery technique and gas source mass spectrometry the data demonstrate that from 0 03 to 0 3 mole percent of calcite is devolatilized at shock pressures significantly lower than those predicted 30 gpa for the onset of volatilization by continuum thermodynamic theory and are in qualitative agreement with release adiabat data for calcite and aragonite carbon and oxygen isotope ratios in the shock released co 2 are the same as those in the unshocked hydrothermal calcite demonstrating that the co 2 comes from the calcite rather than other potential sources

sea surface height variations in the yellow and east china seas 2 ssh variability in the weekly and semiweekly bands two types of models are used to examine the sea surface height ssh variability at the principle short time frequency bands in the yellow and east china seas the models are a primitive equation numerical model and a statistical model based on topex poseidon altimeter data in situ pressure gauge measurements at two mooring locations are first used to evaluate each model in addition a comparison of the numerical and statistical models is made through duplicate analysis of the response to the main extended empirical orthogonal function wind stress modes in the northern yellow sea the wind stress pressure gauge data numerical model and statistical model all indicate local spectral maxima in bands centered on the weekly and semiweekly periods the coherence of the two models with the in situ data is significant down to 3 day periods at the northern mooring and down to 5 day periods at the southern mooring the meridional wind stress variability in the semiweekly band is higher than the weekly band energy in the northern yellow sea and bohai bay and lower than the weekly band energy across the east china sea the ssh variability contained in the weekly and semiweekly bands is largest in the bohai bay and northern yellow sea with a region of high energy along the chinese coast the spatial structure of the weekly and semiweekly ssh variability is similar to the wind stress variability at these bands with semiweekly variability higher in the bohai bay and northern yellow sea and weekly variability dominant in the east china sea

late cretaceous to recent tectonic evolution of the north german basin and the transition zone to the baltic shield southwest baltic sea abstract in this study we investigate the late cretaceous to recent tectonic evolution of the southwestern baltic sea based on a dense grid of seismic reflection profiles this area covers the baltic sea sector of the salt influenced north german basin and its transition to the salt free baltic shield across the tornquist zone the upper cretaceous to recent structural evolution is discussed by means of individual seismic sections and derived high resolution time structure maps of the main horizons i e the upper cretaceous tertiary and pleistocene the upper cretaceous and tertiary layers reveal numerous significant faults throughout the study area several of these faults propagate upwards across the unconsolidated pleistocene sediments and occasionally penetrate the surface the salt influenced north german basin reveals three major fault trends nw se n s and nne ssw several of these faults are located directly above basement sub salt faults and salt pillows the majority of these faults are trending n s to nne ssw and parallel the direction of the gluckstadt graben faults in the salt free tornquist zone we identify two major shallow fault trends which are nw se and ne sw the majority of these faults are located above basement faults following the direction of the tornquist zone we conclude that generally basement tectonics controls activation and trends of shallow faults if salt is present the ductile salt layer causes a lateral shift between the sub and supra salt faults major plate reorganisation related to the africa iberia europe convergence and the subsequent alpine orogeny caused reactivation of pre existing faults and vertical salt movement in the late cretaceous the change of stress orientation from ne sw to a nw se during neogene caused another phase of fault and salt tectonic reactivation we explain that the ice sheet loading and or present day stress field may have acted in combination causing the recent tectonics and upward extension of the faults

impact production of co2 by the cretaceous tertiary extinction bolide and the resultant heating of the earth evidence at the cretaceous tertiary boundary suggests that the proposed extinction bolide struck a continental or shallow marine terrane this evidence includes shocked quartz and feldspar grains found in the boundary layer inherited from a range of rock types a high 87 sr 86 sr ratio in some planktonic fossils which could reflect continental derived sr ref 5 and evidence that the platinum group element rich clay layer is underlain at some localities by a deposit of possible tsunamic origin these observations and data demonstrate that sea level at the end of the cretaceous was 150 200 m higher than at present suggesting the possibility that the extinction bolide struck a shallow marine carbonate rich sedimentary section here we show that the impact of such a bolide 5km in radius onto a carbonate rich terrane would increase the co 2 content of the atmosphere by a factor of two to ten additional dissolution of co 2 from the ocean s photic zone could release much larger quantities of co 2 the impact induced release of co 2 by itself would enhance atmospheric greenhouse heating and give rise to a worldwide increase in temperature from 2 k to 10 k for periods of 10 4 to 10 5 years

dynamic compression and volatile release of carbonates particle velocity profiles upon shock compression and adiabatic release were measured for polycrystalline calcite solenhofen limestone to 12 24 gpa and for porous calcite dover chalk o 1 40 g cm 3 49 porosity to between 5 and 11 gpa the electromagnetic particle velocity gauge method was used upon shock compression of solenhofen limestone the hugoniot elastic limit was determined to vary from 0 36 to 0 45 gpa transition shocks at between 2 5 and 3 7 gpa possibly arising from the calcite ii iii transition were observed for the solenhofen limestone the release paths lie relatively close to the hugoniot evidence for the occurrence of the calcite iii ii transition upon release was observed but no rarefaction shocks were detected initial release wave speeds suggest retention of shear strength up to at least 20 gpa with a possible loss of shear strength at higher pressures the measured equation of state is used to predict the fraction of material devolatilized upon adiabatic release as a function of shock pressure the effect of ambient partial pressure of co 2 on the calculations is demonstrated p co 2 should be taken into account in models of atmospheric evolution by means of impact induced mineral devolatilization mass fractions of co 2 released expected on the basis of a continuum model are much lower than determined experimentally this discrepancy and radiative characteristics of shocked calcite indicate that localization of thermal energy shear banding occurs under shock compression even though no solid solid transitions occur in this pressure range release adiabatic data indicate that dover chalk loses its shear strength when shocked to 10 gpa pressure at 5 gpa the present data are ambiguous regarding shear strength for dover chalk continuum shock entropy calculations result in a minimum estimate of 90 devolatilization upon complete release from 10 gpa for calcite isentropic release paths from calculated continuum hugoniot temperatures cross into the cao solid co 2 vapor field at improbably low pressures for example 10 gpa for a shock pressure of 25 gpa however calculated isentropic release paths originating from pt points corresponding to previous color temperature under shock measurements cross into the melt plus vapor field at pressures greater than 0 5 gpa suggesting that devolatilization is initiated at the shear banding sites

kinematic retro modelling of a cross section through a thrust and fold belt the western irish namurian basin the western irish namurian basin winb developed into a fold and thrust belt at the front of the northward propagating variscan orogenic wedge part of this basin is well exposed along the coast of county clare ireland from a detailed study that used an integrated gps mapping approach we produced a c 50 km long balanced cross section parallel to the tectonic transport vector we sequentially decompacted and retro deformed the namurian strata in 7 stages to evaluate the palinspastic situation of the basin and the amount of shortening by using passive markers in the model and a highly detailed timescale we were able to determine that shortening of the winb from the onset of central clare group sedimentation was 7 44 or 4 07 km of which shortening due to folding accounts for c 2 64 c 1 37 km and therefore c 4 80 c 2 69 km was solely because of thrusting the rate of horizontal shortening ranges from 1 34 mm a 1 this is within typical orogenic values

coastal trapped wave scattering into and out of straits and bays abstract a theory for the generation of coastal trapped waves ctws by an oscillatory coastal flux through a strait is extended so as to make velocity pressure and energy flux everywhere continuous this development is achieved through the inclusion of kelvin and poineare wave modes in a match for pressure leading to a system of linear equations for the unknown amplitudes a kelvin wave incident on the eastern mouth of bass strait for example is shown to preferentially scatter energy into ctw modes 2 and 1 on the shelf as well as driving a poincare wave field that results in a velocity jet trapped to the victorian coast such coastal velocity jets are also a feature of the scattering of ctws incident on a strait for a mode n incident ctw the fraction of net energy flux that enters the strait is also shown to be well approximated by h0bn2 where h0 is the strait depth and bn coupling coefficient the scattering of the remaining energy among other ctw modes is detailed and shown to become larger as the

importance of pre impact crustal structure for the asymmetry of the chicxulub impact crater the final geometry of an impact crater can be significantly influenced by the geological and geomorphological structure of the impact site therefore it may not on its own provide accurate information regarding the direction and angle of impact

direct measurements of chemical composition of shock induced gases from calcite an intense global warming after the chicxulub impact due to the indirect greenhouse effect of carbon monoxide abstract shock induced devolatilization in hypervelocity impacts has been considered to play important roles in the atmospheric evolution and mass extinctions in earth s history although the chemical composition of shock induced gas species from carbonate rocks has been considered as a key to understand the environmental change after the chicxulub impact it has not been investigated extensively before here we conduct direct measurements of the chemical composition co co 2 of shock induced gas species from calcite caco 3 using both a laser gun system and an isotopic labeling technique the co co 2 ratio of the shock induced gas species from calcite is measured to be 2 02 0 41 suggesting that gaseous co has been dominant in the shock induced gases in the chicxulub impact in order to evaluate the environmental effects of the injection of co gas we investigated the post impact atmospheric chemistry by incorporating our experimental results into a tropospheric photochemical model the results suggest that an intense 2 5 c global warming would have lasted for several years after a chicxulub size impact mainly due to the greenhouse effect of tropospheric o 3 which is produced via photochemical reactions associated with co gas such an intense global warming could have damaged the biosphere in the mass extinction at the cretaceous paleogene k p boundary

chicxulub crater a possible cretaceous tertiary boundary impact crater on the yucatan peninsula mexico we suggest that a buried 180 km diameter circular structure on the yucatan peninsula mexico is an impact crater its size and shape are revealed by magnetic and gravity field anomalies as well as by oil wells drilled inside and near the structure the stratigraphy of the crater includes a sequence of andesitic igneous rocks and glass interbedded with and overlain by breccias that contain evidence of shock metamorphism the andesitic rocks have chemical and isotopic compositions similar to those of tektites found in cretaceous tertiary k t ejecta a 90 m thick k t boundary breccia also containing evidence of shock metamorphism is present 50 km outside the crater s edge this breccia probably represents the crater s ejecta blanket the age of the crater is not precisely known but a k t boundary age is indicated because the crater is in a thick carbonate sequence shock produced co2 from the impact may have caused a severe greenhouse warming

the thermal history of the western irish onshore we present here a low temperature thermochronological study that combines the apatite fission track and u th he dating methods with a pseudo vertical sampling approach to generate continuous and well constrained temperature time histories from the onshore irish atlantic margin the apatite fission track and u th he ages range from the late jurassic to early cretaceous and the mean track lengths are relatively short thermal histories derived from inverse modelling show that following post orogenic exhumation the sample profiles cooled to c 75 c a rapid cooling event to surface temperatures occurred during the late jurassic to early cretaceous and was diachronous from north to south it was most probably caused by c 2 5 km of rift shoulder related exhumation and can be temporally linked to the main stage of mesozoic rifting in the offshore basins a slow phase of reheating during the late cretaceous and early cenozoic is attributed to the deposition of a thick sedimentary sequence that resulted in c 1 5 km of burial our data imply a final pulse of exhumation in neogene times probably related to compression of the margin however it is possible that an early cenozoic cooling event compatible with our data but not seen in our inverse models accounts for part of the cenozoic exhumation supplementary material details on the apatite fission track and u th he methods are available at www geolsoc org uk sup18765

review and update of the applications of organic petrology part 1 geological applications abstract organic petrology developed as coal petrology at the beginning of the 20th century dedicated mainly to the study of coals because of their utilization in industry coal petrology was then considered a branch of coal science later with the development of specialized nomenclature classification of coal components and the standardization and improvement of analytical microscopical methods this discipline expanded in interests and name becoming organic petrology organic petrology carries a broader context being as well a tool applied in the study of dispersed organic matter in sedimentary rocks due to its importance in exploration for fossil fuel resources at present organic petrology is a discipline widely recognized for its role in fundamental and applied research with respect to both coal utilization and in geosciences throughout the 20th century several important monographs have been published on the discipline of organic petrology including stach s textbook of coal petrology 1st edition 1935 2nd 1975 3rd 1982 updated as the more general organic petrology by taylor et al 1998 more recently the text applied coal petrology the role of petrology in coal utilization was published by suarez ruiz and crelling 2008 this review is the first in a two part review series that describes and updates the role of organic petrology in geosciences a second part complementing this one and focused on the applications of organic petrology to other scientific fields will follow

the nature of shock induced calcite caco3 devolatilization in an open system investigated using a two stage light gas gun abstract the shock induced decarbonation of non porous calcite was investigated in an open system over a wide range of peak shock pressures using a two stage light gas gun and a quadrupole mass spectrometer we developed a new experimental technique that avoids chemical contamination from the acceleration gas used in the gun high speed imaging and spectroscopic observations were conducted simultaneously to investigate the validity of the experimental procedure the decarbonation efficiency along the hugoniot curve changed at around 50 gpa the approximate incipient decarbonation pressure predicted by the previous theoretical studies decarbonation albeit at a low efficiency was detected at pressures below the 50 gpa threshold as observed in previous experimental studies possibly as a result of energy localization due to a process like shear banding a simple theoretical model for shock induced decarbonation during isentropic release was constructed based on the entropy method and the lever rule assuming the experimental conditions the predicted amount of released co 2 as a function of the peak shock pressure agreed well with the experimental results at pressures exceeding 50 gpa strongly suggesting that the amount of shock induced co 2 gas was determined only by the shock induced entropy gain and by the entropies for incipient and complete decarbonation at the ambient pressure in future experiments the new method will be used for quantitative measurements of the chemical composition of impact induced gases derived from other solid materials the proposed method is useful in determining the peak shock pressure required for vaporization devolatilization of geologic materials and for estimating the final chemical composition of impact induced vapor clouds

implications for organic maturation studies of evidence for a geologically rapid increase and stabilization of vitrinite reflectance at peak temperature cerro prieto geothermal system mexico discussion a short term rapid heating and cooling of the rock in well m 94 below 1300 m was caused by a pulse of hot water passing through the edge of the cerro prieto mexico geothermal system below 1300 m the peak paleotemperatures were about 225 250 degrees c but equilibrium well log temperatures indicate a decrease to 150 210 degrees c at present this hot water pulse sharply increased vitrinite reflectance to levels comparable to those measured in the central part of the system even though studies of apatite fission track annealing indicate that the duration of heating was only 10 0 10 1 yr in m 94 in contrast to 10 3 10 4 yr in the central part of the system these data indicate that sedimentary organic matter chemically reacts quickly to temperature increases of about 125 degrees c above ambient even when the higher temperature existed for only 10 0 10 1 yr the quick change of the vitrinite reflectance geothermometer indicates that thermal maturation reactions can stabilize after a geologically short period of heating to a level consistent with peak temperature under moderate to high temperature diagenesis in open fluid rich geothermal systems cerro prieto is one of the most intensively studied and well known geothermal systems in the world thus data from cerro prieto are a benchmark to compare with the predictions of published thermal maturation models such as those formulated by j karweil n v lopatin and a k burnham and j j sweeney these thermal maturation models inaccurately predict duration of heating at cerro prieto the kinetic equations used in these models explicitly allow thermal maturation to continue indefinitely at peak temperature which does not seem to be the case at cerro prieto

relationship between impact crater size and severity of related extinction episodes abstract how large must an extraterrestrial impact be to cause a peak episode of increased extinctions of life impact energies 3 107 mt tnt associated with terrestrial impact craters with final diameters 100 km seem to be required to generate significant widespread climatic effects from sub micron dust and soot in the atmosphere leading to a distinct extinction episode 15 extinction of marine genera impacts creating craters smaller than 100 km in final diameter in the 106 to 107 mt tnt range are capable of mostly regional destruction with minimal impact on global climate or biota these results are supported by the fact that the ages of the four known 100 km diameter craters of the last 260 my popigai chicxulub morokweng and manicouagan are all correlative with times of documented extinction episodes whereas smaller craters are not the largest crater the 180 km diameter chicxulub crater a 108 mt tnt event is associated with the more severe major mass extinction event 45 extinction of genera at the end of the cretaceous the percent species extinctions show a significant linear relationship with final crater diameter and impact energy the very large chicxulub impact lies close to the predicted curve of percent extinction versus impact crater diameter and energy but the low angle of impact an unusual composition of the target area with thick sediments rich in carbonates sulfates and organic material and a large excavated transient crater may have led to the generation of unusually large amounts of co2 widely distributed dust soot and sulfate aerosols and a uniquely severe impact related environmental disaster chicxulub may thus be the only large body impact associated with a major mass extinction in the phanerozoic target sensitivity may apply to large impacts into ocean crust having only a thin cover of organic poor and carbonate poor pelagic sediments and thus even large oceanic impacts which are still unknown may not produce enough dust soot and aerosols to cause environmental crises leading to global extinction peaks above background levels

an asymmetric upwind flow yellow sea warm current 1 new observations in the western yellow sea 1 the winter water mass along the yellow sea trough yst especially on the western side of the trough is considerably warmer and saltier than the ambient shelf water mass this observed tongue shape hydrographic feature implies the existence of a winter along trough and onshore current often referred to as the yellow sea warm current yswc however the yswc has not been confirmed by direct current measurements and therefore skepticism remains regarding its existence some studies suggest that the presence of the warm water could be due to frontal instability eddies or synoptic scale wind bursts it is noted that in situ observations used in most previous studies were from the central and eastern sides of the yst even though it is known that the warm water core is more pronounced along the western side data from the western side have been scarce here we present a set of newly available chinese observations including some from a coordinated effort involving three chinese vessels in the western yst during the 2006 2007 winter the data show unambiguously the existence of the warm current on the western side of yst both the current and hydrography observations indicate a dominant barotropic structure of yswc the westward deviation of yswc axis is particularly obvious to the south of 35 n and is clearly associated with an onshore movement of warm water to the north of 35 n the yswc flows along the bathymetry with slightly downslope movement we conclude that the barotropic current is mainly responsible for the warm water intrusion while the ekman and baroclinic currents play an important but secondary role these observations help fill an observational gap and establish a more complete view of the yswc

impact winter and the cretaceous tertiary extinctions results of a chicxulub asteroid impact model abstract the chicxulub impact crater in mexico is the site of the impact purported to have caused mass extinctions at the cretaceous tertiary k t boundary 2 d hydrocode modeling of the impact coupled with studies of the impact site geology indicate that between 0 4 and 7 0 1017 g of sulfur were vaporized by the impact into anhydrite target rocks a small portion of the sulfur was released as so3 or so4 which converted rapidly into h2so4 aerosol and fell as acid rain a radiative transfer model coupled with a model of coagulation indicates that the aerosol prolonged the initial blackout period caused by impact dust only if the aerosol contained impurities a larger portion of sulfur was released as so2 which converted to aerosol slowly due to the rate limiting oxidation of so2 our radiative transfer calculations combined with rates of acid production coagulation and diffusion indicate that solar transmission was reduced to 10 20 of normal for a period of 8 13 yr this reduction produced a climate forcing cooling of 300 wm 2 which far exceeded the 8 wm 2 greenhouse warming caused by the co2 released through the vaporization of carbonates and therefore produced a decade of freezing and near freezing temperatures several decades of moderate warming followed the decade of severe cooling due to the long residence time of co2 the prolonged impact winter may have been a major cause of the k t extinctions

the clare basin a geological and geophysical outline the clare basin fig 1 is a poorly documented carboniferous basin remnant situated offshore west of ireland which is considered to be an extension of the onshore west clare namurian basin wcnb it has in the past been variously described as or as part of the clare shelf and shannon basin e g cope et al 1992 the shannon trough e g sevastopulo 1981 and the dingle shannon basin e g gardiner maccarthy 1981 it lies immediately north of the iapetus suture which is assumed to have closed during the devonian figure 1 shows the general location of the clare basin the outline of the younger porcupine basin and slyne trough and the onshore geological outcrop map also shown are the locations of boreholes and the line of cross section figured in the paper

shock temperature in calcite caco3 at 95 160 gpa the temperatures induced in crystalline calcite caco 3 upon planar shock compression 95 160 gpa are reported from two stage light gas gun experiments temperatures of 3300 5400 k are obtained by fitting six channel optical pyrometer radiances in the 450 900 nm range to the planck gray body radiation law thermodynamic calculations demonstrate that these temperatures are some 400 1350 k lower than expected for vibronic excitations of the lattice with a 3r mole atom specific heat r is gas constant the temperature deficit along the hugoniot is larger than that expected from only melting in addition to melting it appears likely that shock induced decomposition of calcite occurs behind the shock front we modeled disproportionation of calcite into cao solid plus co 2 gas for temperature calculations specific heat at constant volume for 1 mole of co 2 is taken to be 6 7r as compared to 9r in the solid state whereas a mole of calcite and a mole of cao have their solid state values 15r and 6r respectively calculations suggest that the calcite decomposes to cao and co 2 at 110 10 gpa along the hugoniot recent reanalysis of earlier visar measurements of particle velocity profiles 1 indicates that calcite shocked to 18 gpa undergoes disproportionation at much lower pressures upon isentropic expansion

the role of pressure solution seam and joint assemblages in the formation of strike slip and thrust faults in a compressive tectonic setting the variscan of south western ireland abstract the ross sandstone in county clare ireland was deformed by an approximately north south compression during the end carboniferous variscan orogeny the initial assemblage consists of mutually abutting orthogonal arrays of 170 oriented set 1 joints veins jvs and approximately 75 oriented set 1 pressure solution seams psss formed under the same stress conditions orientations of splay jvs and psss set 2 suggest a clockwise remote stress rotation of about 35 responsible for the contemporaneous shearing of the set 1 arrays among these nearly orthogonal strike slip faults the prominent set is sub parallel to set 1 jvs these faults are formed by the linkage of en echelon segments with broad damage zones responsible for right lateral offsets of hundreds of meters thrust faults with up to 30 m of offset initiate within shale horizons and follow either the psss in the sandstones or high angle shales within tilted sequences within the large thrust fault zones compartmentalised blocks of rocks are bounded by thrust faults segments with various dip angles strike slip and thrust faults are contemporaneous and owe their existence to initial weaknesses in the form of jvs and psss rather than by switching relative stress magnitudes and orientations associated with andersonian models of faults and related stress orientations

frontal circulation and westward transversal current at the yellow sea entrance in winter 1 during the wintertime monsoon a tongue shaped thermohaline front is established at the yellow sea ys entrance where the cheju warm current cwc water originating in the kuroshio and the ys cold water meet the frontal circulation as well as the frontal structure has been investigated by analyzing comprehensive conductivity temperature density data float tracks current data and wind data the front develops by the westward advance of the cwc water but it is bounded by the shallow changjiang banks cb that acts like a stopper in the deep part of the ys entrance the northern part of the tongue shaped front displays a wave like motion of 20 km in amplitude and 80 km in wavelength and isotherms isohalines and isopycnals are declined downward toward the north the geostrophic current field indicates formation of a cyclonic circulation along the front which consists of a westward transversal current tc along 34 n and a southeastward outflow along the 50 m isobath of the cb the westward trajectories of floats along the northern front support existence of the tc and a superposition of float tracks evidences cyclonic frontal circulation the new observational findings of the tc and the cyclonic circulation do not match the classical paradigm of a northerly wind driven circulation which consists of the northward inflow through the central trough and the southward outflow on the coastal sides the cyclonic turning of the cold water around the warm tongue stands in contrast with the anticyclonic rounding of the warm cwc water around jeju do

the impact of the cretaceous tertiary bolide on evaporite terrane and generation of major sulfuric acid aerosol abstract impact glasses from the k t boundary in haiti include high ca glasses with up to 1 wt so3 formed by the fusion of anhydrite or gypsum rich evaporite sediments in the presence of high silica melts derived from melting of continental crust experimental studies have duplicated these two melts by fusion of gypsum and andesite and suggest a formation temperature of 1300 c geochemical evidence from the glasses is consistent with their derivation from the 180 km diameter chicxulub impact crater on the yucatan peninsula mexico situated in a thick late cretaceous evaporite succession this large diameter crater is most likely the result of a cometary impact on the basis of bolide scaling from the ir anomaly in k t boundary sediments the sulfur degassing associated with formation of the high ca glass alone could have formed a2 1016 g h2so4 stratospheric aerosol however the total sulfur degassing from the evaporite rich sediments in the chicxulub impact site may have led to formation of3 8 1018 to1 3 1019 g sulfate aerosol and global atmospheric mass loading from the sulfate aerosol alone is estimated to beof the order of 1 2 6 g cm 2 combined with the great optical depth estimates of pollack et al 1 and covey et al 2 resulting from an impact dust cloud the sulfate aerosol may have contributed not only to a rapid decline in global surface temperatures to near freezing in about one week but also prolonged the cooling for several years because of the time dependent conversion of so2 to h2so4 aerosol in the atmosphere the contribution of sulfur to acid rain following the k t boundary event may have equalled the proposed rainout of nitric acid

trajectories and distribution of material ejected from the chicxulub impact crater implications for postimpact wildfires 1 the trajectories of low and high energy ejecta from the chicxulub impact crater have been computed using a numerical code and compared with analyses of debris deposited in k t boundary sections these calculations indicate that low energy ejecta produces centimeter to meter thick deposits within 4000 km of the point of impact although its azimuthal distribution depends on the incident angle of the projectile with the surface of the earth the high energy ejecta or vapor plume rises through the atmosphere and isotropically expands at the top of the atmosphere the velocity of this ejecta increases as it rises approximately 12 of the high energy ejecta is lost because it reaches escape velocities while 25 of the material reaccretes within 2 hours 55 reaccretes within 8 hours and 85 reaccretes within 72 hours this ejecta is distributed globally but it is concentrated around the chicxulub impact site and at the antipode corresponding to india and the indian ocean 65 million years ago it is also slightly smeared in a longitudinal direction because of earth s rotation because this debris does not reaccrete all at once the collisional shock heating of the atmosphere will be drawn out over a period of a few days and will occur in pulses this could be an important factor when calculating postimpact chemical reactions in the stratosphere the calculations also indicate the ejecta would have ignited wildfires on several continents around the world although the distribution of those fires depends partly on the trajectory of the projectile

alongshore and cross shore circulations and their response to winter monsoon in the western east china sea abstract an array of four bottom mounted acoustic doppler current profilers adcps were deployed during the winter of 2008 28 december 2008 to 12 march 2009 along a cross shelf section in the western east china sea to investigate the winter circulation and its response to wind during the observation period the observed subtidal currents exhibit coherent spatial structure and temporal variation in terms of their mean seasonal trend intra seasonal and synoptic variability the subtidal currents are polarized roughly in the alongshore direction parallel to local isobaths and the weak cross shore current is closely linked to the alongshore component the temporal variation of the currents follows the rhythm of wind stress sea level and sea level difference at the synoptic scale the mean currents are basically composed of two anti parallel currents in the alongshore direction the east china sea coastal current ecscc flows southwestward along the inner shelf and the taiwan warm current twc flows in the opposite direction along the outer shelf the strongest current occurs over the mid shelf as a coastal jet the intra seasonal currents exhibit an expansion and intensification of the ecscc along with shrinking and weakening the alongshore component of the twc there is a significant increase in onshore current particularly over the mid shelf the fluctuations of synoptic currents show a significant positive correlation with wind stress and the fluctuations are negatively correlated with sea level and sea level difference the coherent spatial structure of the currents indicates that the depth independent column motion is related to the sea level difference through a barotropic pressure gradient the vertical shear of currents is related to the density related baroclinic pressure gradient in the whole water column and to the friction within the surface and bottom boundary layers

organic carbon losses during burial and thermal maturation of normal marine shales the percentage of organic carbon lost during the burial diagenesis of normal marine shales those originally deposited in oxygenated bottom waters can be estimated by using the ratio of organic carbon c to pyrite sulfur s and assuming that the mean initial burial value of c s for such sediments has been approximately constant since the devonian plots of mean c s vs vitrinite reflectance r sub 0 for some sedimentary basins of jurassic and carboniferous age show a monotonic decrease of c s with increasing r sub 0 macrofossils

the development and seismic expression of synsedimentary features within the chalk of southern england seismic reflection data acquired onshore to the north of bournemouth southern england image clearly a series of prominent concave up troughs or depressions and concave down mounded structures within the white chalk subgroup the chalk lithostratigraphy in the area of study is established from borehole geophysical log correlations these correlations then provide calibration of the seismic reflection data indicating that the structures are concentrated at levels between the lewes nodular chalk formation and tarrant chalk member and towards the base of the portsdown chalk formation onlap downlap and truncation of reflectors are observed with the most dramatic features forming a stacked series directly overlying faulting of jurassic strata similar stratal geometries have been described from comparable levels in the chalk of the north sea and in outcrop in britain and france to many they represent channels formed by submarine erosion and redeposition of the chalk during relative sea level falls linked to tectonics we also interpret a number of apparently incisive structures and slumped infill sequences described here as being of primary syndepositional origin the slumping and the close association of these features with underlying faults and proximity to nearby major crustal faults may be indicative of submarine erosion of the chalk caused by sea level changes linked to syndepositional fault movements however evidence of toplap downlap pairs is also suggestive of more aggradational mounding or laterally migrating surfaces or facies belts the presence of any such structures implies rapid lateral variations in the chalk that would have implications not only for aquifer management and future storage schemes but also during the processing of seismic reflection data and general studies and correlations of the chalk across southern britain

ice load induced tectonics controlled tunnel valley evolution instances from the southwestern baltic sea abstract advancing ice sheets have a strong impact on the earth s topography for example they leave behind an erosional unconformity bulldozer the underlying strata and form tunnel valleys primarily by subglacial melt water erosion and secondarily by direct glacial erosion the conceptual models of the reactivation of faults within the upper crust due to the ice sheets load are also established however this phenomenon is also rather under explored here we propose a causal link between ice load induced tectonics the generation of near vertical faults in the upper crust above an inherited deep rooted fault and the evolution of tunnel valleys the kossau tunnel valley in the southeastern bay of kiel has been surveyed by means of high resolution multi channel seismic and echosounder data it strikes almost south to north and can be mapped over a distance of ca 50 km it is 1200 8000 m wide with a valley of up to 200 m deep quaternary deposits fill the valley and cover the adjacent glaciogenic unconformity a near vertical fault system with an apparent dip angle of 80 which reaches from the top zechstein upwards into the quaternary underlies the valley the fault partially pierces the seafloor and growth is observed within the uppermost quaternary strata only consequently the fault evolved in the late quaternary the fault is associated with an anticline that is between 700 and 3000 m wide and about 20 40 m high the fault anticline assemblage neither resembles any typical extensional compressional or strike slip deformation pattern nor is it related to salt tectonics based on the observed position and deformation pattern of the fault anticline assemblage we suggest that these structures formed as a consequence of the differential ice load induced tectonics above an inherited deep rooted sub salt fault related to the gluckstadt graben lateral variations in the ice load during the ice sheet s advance caused differential subsidence thus rejuvenating the deep rooted fault as a result the inherited fault propagated upwards across the zechstein and post permian overburden and further grew during the ice sheet s retreat the developing fault and anticline system under the ice sheet created a weakness zone that facilitated erosion by pressurized glacial and subglacial melt water as well as by the glaciers themselves near vertical faults cutting through the post permian are abundant in the southwestern baltic realm which implies that the ice load induced tectonic activity described above was not an isolated incident

coastally trapped long waves in the yellow sea abstract the coastally trapped long wave theory is adapted to a double shelf bottom topography in the development of a barotropic long wave model for calculating wintertime wind driven currents and sea level fluctuations in the yellow sea the low frequency free wave solutions consist of two infinite sets of modes one set trapped to each side of the trough that separates the two plane shelves the phase propagation of either set of waves depends upon the slopes of both shelves forced wave motions are considered for geostrophic winds calculated at 35 n 125 e for the period of january april 1986 for which point measurements of currents and sea level fluctuations are available comparison to these measurements shows that the model reproduces reasonably well upwind flow events in the trough that dominate the wind driven wintertime regime the anatomy of a typical event of this type shows that the korea side kelvin wave is mainly responsible for the establishment of the downwind setup in sea level and in t

a comparison of long coastal trapped wave theory with observations off peru abstract the agreement between coastal trapped wave theory and observation is studied for the case of observations made off peru during the 1977 cuea joint ii experiment wave properties are calculated using a numerical model with realistic horizontally uniform stratification and realistic bottom topography these properties are then explored as a function of the ratio of the first internal rossby radius of deformation to the shelf slope width the agreement of observed and calculated first mode free wave phase speeds 230 cm s 1 is excellent while modal structures agree more poorly a forced wave calculation using observed winds and currents as input is used to hindcast alongshore currents and sea level in the frequency band where smith 1978 observed free coastal trapped waves during 1977 the model suggests that most of the observed sea level and alongshore velocity fluctuations in the 5 10 day period band are due to free waves originating equatorward of 5 deg s while winds between 5 deg s and

cretaceous tertiary chicxulub impact angle and its consequences the chicxulub impact structure exhibits asymmetries in its geophysical signatures that closely resemble asymmetries produced by oblique impacts in laboratory experiments and recognized on planetary surfaces these asymmetric signatures suggest a trajectory for the chicxulub bolide from the southeast to the northwest at a 20 30 angle from the horizontal as a result biotic extinctions may have been most severe and catastrophic in the northern hemisphere geographic variation in the magnitude of the cretaceous tertiary k t fern spike and palynofloral extinctions are consistent with the proposed trajectory

thermal maturity patterns in alaska implications for tectonic evolution and hydrocarbon potential nearly 10 000 vitrinite reflectance and conodont color alteration index determinations from sedimentary rocks in alaska were used to produce a thermal maturity map of rocks exposed at the surface and to evaluate subsurface thermal maturity relations in the colville and cook inlet basins rocks exposed at the surface of the tertiary interior basins and in the aleutian forearc and backarc basins uniformly are of very low thermal maturity indicating that these basins are at or near maximum burial have seen little uplift and exhumation and are probably thermally immature with respect to hydrocarbon generation in contrast many sedimentary basins show elevated levels of thermal maturity at the surface with the highest values at basin margins this geometry suggests a patt rn of greater uplift along basin margins possibly reflecting isostatic readjustments as crustal loads are removed by erosion we investigated thermal maturity relations in three sedimentary basins colville cook inlet and kandik in more detail thermal maturity patterns in the colville basin are broadly asymmetric indicating systematic differential uplift ranging from a minimum of no uplift in the north point thomson area to 9 13 km of uplift and exhumation in the central brooks range even greater uplift further to the south is indicated by the presence of greenschist facies and higher grade metamorphic rocks this pattern may reflect the deflexing of the lithosphere subsequent to the principal episode s of crustal convergence and thickening these patterns further suggest a similar thermal history for the proximal colville basin and the northern foothills belt suggesting the possibility of hydrocar on accumulations in the foothills thermal maturity isograds within the brooks range cut major thrust faults indicating that maximum burial postdated the principal phases of thrusting in contrast isograds in the foothills belt to the north are warped broadly by local structure indicating continued north south shortening subsequent to maximum burial such deformation could have remobilized hydrocarbons in early traps a broad southward extension of thermally immature rocks in the central portions of the foothills belt suggests relatively young east west shortening parallel to the strike of the orogene a feature that to date has not been included in regional tectonic syntheses alternatively the thermal maturity pattern could be explained by tectonically unrelated episodes of uplif in the eastern and western parts of the brooks range in the cook inlet basin vitrinite reflectance isograds also are indicative of relatively greater uplift at the basin margins than at the basin center which appears to be presently at its maximum burial depth uplift in the cook inlet basin may reflect compression along the faults bounding the basin relatively high thermal maturity along the western margin of the basin also may reflect magmatic heat sources from the alaska peninsula aleutian volcanic arc the seldovia arch a major structural feature of the end page 1874 basin does not appear to deform vitrinite reflectance isograds implying that deformation on that structure ceased prior to maximum burial in the kandik basin a thermal maturity anomaly thermally mature younger rocks in fault contact with thermally immature older rocks provides clues to the nature and timing of east west thrusting mesozoic foreland basin deposits associated with thrusting buried paleozoic rocks of the easternmost part of this fold and thrust belt to relatively shallow depths driving potential hydrocarbon source rocks into the oil generation window the western foreland basin deposits were overridden by advancing thrusts and tectonically buried to as deep as 10 km these disparate thermal domains are juxtaposed along the glenn creek fault which may represent a terrane boundary in east central alaska

energy volatile production and climatic effects of the chicxulub cretaceous tertiary impact a comprehensive analysis of volatiles in the chicxulub impact strongly supports the hypothesis that impact generated sulfate aerosols caused over a decade of global cooling acid rain and disruption of ocean circulation which contributed to the mass extinction at the cretaceous tertiary k t boundary the crater size meteoritic content of the k t boundary clay and impact models indicate that the chicxulub crater was formed by a short period comet or an asteroid impact that released 0 7 3 4 x 10 31 ergs of energy impact models and experiments combined with estimates of volatiles in the projectile and target rocks predict that over 200 gigatons gt each of so2 and water vapor and over 500 gt of co2 were globally distributed in the stratosphere by the impact additional volatiles may have been produced on a global or regional scale that formed sulfate aerosols rapidly in cooler parts of the vapor plume causing an early intense pulse of sulfuric acid rain estimates of the conversion rate of stratospheric so2 and water vapor to sulfate aerosol based on volcanic production of sulfate aerosols coupled with calculations of diffusion coagulation and sedimentation demonstrate that the 200 gt stratospheric so2 and water vapor reservoir would produce sulfate aerosols for 12 years these sulfate aerosols caused a second pulse of acid rain that was global radiative transfer modeling of the aerosol clouds demonstrates 1 that if the initial rapid pulse of sulfate aerosols was global photosynthesis may have been shut down for 6 months and 2 that for the second prolonged aerosol cloud solar transmission dropped 80 by the end of first year and remained 50 below normal for 9 years as a result global average surface temperatures probably dropped between 5 degrees and 31 degrees k suggesting that global near freezing conditions may have been reached impact generated co2 caused less than 1 degree k greenhouse warming and therefore was insignificant compare to the sulfate cooling the magnitude of sulfate cooling depends largely upon the rate of ocean mixing as surface waters cool sink and are replaced by upwelling of deep ocean water this upwelling apparently drastically altered ocean stratification and circulation which may explain the global collapse of the delta 13c gradient between surface and deep ocean waters at the k t boundary

cross flows in the taiwan strait in winter abstractin winter a branch of the china coastal current can turn in the taiwan strait to join the poleward flowing taiwan coastal current the associated cross strait flows have been inferred from hydrographic and satellite data from observed abundances off northwestern taiwan of cold water copepod species calanus sinicus and in late march of 2012 also from debris found along the northwestern shore of taiwan of a ship that broke two weeks earlier off the coast of china the dynamics related to such cross flows have not been previously explained and are the focus of this study using analytical and numerical models it is shown that the strait s currents can be classified into three regimes depending on the strength of the winter monsoon equatorward poleward for northeasterly winds stronger weaker than an upper lower bound and cross strait flows for relaxing northeasterly winds between the two bounds these regimes are related to the formation of the stationary rossby wave over the changyun ridge

the thermal setting of carboniferous basins in relation to the variscan orogeny in central and western europe abstract the coal basins at the variscan front in western europe provided the first examples of prefolding coalification that was linked to an early high geothermal history the coalification occurred almost contemporaneous with sedimentation and prior to folding the examination of a number of basins from southwestern britain to poland suggests a generalization of this coalification scheme and an extension of it to the inner variscan parts of the rhenish and harz massifs the latter form with the coal basins a repetition of similar troughs from the first flysch deposits up to the last molasse deposits intermontane coal basins of various types in this belt also reveal coalification linked to high geothermies concomitant to variscan sedimentation although sometimes ending during folding conversely the great platforms surrounding the orogen only display normal burial coalification with the exception of isolated structures that were active during and mostly after the variscan period the variscan range was recently interpreted as having been formed under a double influence crustal extensions in the framework of insular arcs and continental collisions that were responsible for folding high paleogeothermal flows are characteristic of the former so they accompanied the formation of subsidence basins