comparative petroleum systems analysis of the interior basins of turkey implications for petroleum potential abstract the interior basins of turkey remain effectively unexplored and their petroleum systems are poorly understood this paper presents a comparative summary of the geological evolution petroleum potential and prospectivity of the central tuz golu sivas and cankiri and east anatolian mus hinis pasinler horasan and tercan askale basins using geological seismic geochemical and petrophysical data and a series of quantitative basin models the studied basins are ranked on the basis of source effectiveness reservoir quality seal efficiency and the timing of hydrocarbon expulsion and migration relative to trap formation a qualitative risk assessment based on the elements of the petroleum system is used to evaluate the likelihood of hydrocarbon discovery in each of the basins this study shows that the chance of hydrocarbon discovery in the east anatolian basins is unlikely very unlikely and tuz golu sivas and cankiri basins are equally likely unlikely unlikely likely and unlikely respectively heavy oil and minor gas associated with two mature petroleum systems were discovered in the tuz golu basin various trap forming mechanisms such as salt tectonics and middle eocene compression accompanied by the effective sealing capacity of the eocene evaporites favor the hydrocarbon exploration potential of the tuz golu basin the highest exploration risk in the tuz golu basin arises from the poor quality sandstone reservoirs the biggest risk factor in the eastern anatolian basins is insufficient thermal maturity despite the presence of good quality source rocks the sivas basin is one of the most promising interior basins of turkey due to the presence of multiple mature petroleum systems and high quality reservoirs there is a high chance of accumulation of multi phase hydrocarbons in the eocene and miocene traps the major problem in the sivas basin is the lack of an efficient seal rock the cankiri basin contains all of the necessary elements of an ideal petroleum system except the presence of an organic rich source rock thus the chance of hydrocarbon discovery in the cankiri basin is low

effect of sedimentary heterogeneities on hydrocarbon accumulations in the permian shanxi formation ordos basin china insight from an integrated stratigraphic forward and petroleum system modelling abstract sedimentary heterogeneities are ubiquitous in nature and occur over a range of scales from core reservoir to basin scales they may thus exert significant influences on hydrocarbon generation migration and accumulation the sedimentary heterogeneities of the permian shanxi formation in the ordos basin china were modelled using sedsim a stratigraphic forward modelling program the simulation results were then used to construct a 3d petroleum system model using petromod the effects of sedimentary heterogeneities on hydrocarbon accumulations were evaluated by comparing the integrated sedsim petromod model with the classic 3d basin model the sedsim simulation shows that considerable sedimentary heterogeneities are present within the shanxi formation as a result of the interplay of the initial topography tectonic subsidence base level change and sediment inputs a variety of lithologies were developed both laterally and vertically within the shanxi formation at kilometre and metre scales respectively with mudstones mainly developed in the depositional centre while sandstones developed in the southern and northern margin areas a typical source ward retrogradation is well developed within the lower shanxi formation a base case classic 3d basin model was constructed to quantify the permian petroleum system in the ordos basin the geological and thermal models were calibrated using vr and borehole temperature data the source rocks of the upper paleozoic became mature r o 0 5 and high mature r o 1 2 in the late triassic and late jurassic respectively in the central and southern areas during the early cretaceous a tectonically induced geothermal event occurred in the southern ordos basin this caused the source rocks to reach over maturity r o 2 0 quite rapidly in the early late cretaceous in the central and southern areas all the source rock transformation ratios tr at present are greater than 70 in the p 1 coal and p 1 mudstone layers with tr values approaching 100 in the central and southern areas the transformation ratios of the p 1 limestone are close to 100 over the entire interval in the base case model a large amount of hydrocarbons appear to have been expelled and migrated into the shanxi formation but only a minor amount was accumulated to form reservoirs in the model the shanxi formation sandstone layer was set to be homogeneous vertically and there was no regional seal rocks present at the top of the shanxi formation therefore hydrocarbons could not be trapped effectively with only minor accumulations in some local structural highs where hydrocarbons are trapped both at the top and in the up dip direction by the adjacent mudstone facies in contrast the integrated sedsim petromod model takes into account of the internal lithological and sedimentary facies heterogeneities within the shanxi formation forming complex contiguous sandstone mudstone stacking patterns hydrocarbons were found to have accumulated in multiple intervals of lithological traps within the shanxi formation the results indicate that lithological distinctions controlled by sedimentary heterogeneities in three dimensions can provide effective sealing in both the top and up dip directions for hydrocarbon accumulations with gas being mainly accumulated near the depocentre where lithological traps usually formed due to frequent oscillations of the lake level

cold event at 8200 yr b p recorded in annually laminated lake sediments in eastern europe a quantitative annual mean temperature reconstruction from an annually laminated lake sediment sequence in estonia eastern europe shows a distinct cold period at 8400 8080 yr b p before a d 2000 the timing is consistent with that seen in the greenland ice core data and various high resolution records from western europe during maximal cooling at 8250 8150 yr b p the annual mean temperature in estonia was 2 0 c colder than prior to and 3 0 c colder than after the cooling the pollen stratigraphic and sedimentological data suggest especially cold and snowy winter conditions the duration and amplitude of the cold event agree with the modeled impact of a sudden freshening of the north atlantic surface water and subsequent perturbation of the thermohaline circulation provided that the cold event was caused by a pulse of freshwater from the melting laurentide ice sheet to the north atlantic the results indicate a strong teleconnection between the north atlantic oceanic forcing and the east european climate at least up to long 26 e mediated probably by the changing intensity of the zonal atmospheric circulation

holocene climatic instability a prominent widespread event 8200 yr ago the most prominent holocene climatic event in greenland ice core proxies with approximately half the amplitude of the younger dryas occurred 8000 to 8400 yr ago this holocene event affected regions well beyond the north atlantic basin as shown by synchronous increases in windblown chemical indicators together with a significant decrease in methane widespread proxy records from the tropics to the north polar regions show a short lived cool dry or windy event of similar age the spatial pattern of terrestrial and marine changes is similar to that of the younger dryas event suggesting a role for north atlantic thermohaline circulation possible forcings identified thus far for this holocene event are small consistent with recent model results indicating high sensitivity and strong linkages in the climatic system

selective organic matter preservation in burn down turbidites on the madeira abyssal plain 1 oxidized intervals of five organic rich madeira abyssal plain map turbidites deposited during the miocene pliocene and pleistocene all displayed comparable major loss of total organic carbon toc 84 3 1 accompanied by a negative isotopic 13c shift ranging from 0 3 to 2 9 major but significantly lower loss of total nitrogen ntot 61 7 1 also occurred leading to a decrease in toc relative to ntot c ntot and a 1 3 to 2 7 ntot isotopic 15n shift compound specific isotopic measurements on plant wax n alkanes indicate the terrestrial organic component in the unoxidized deposits is 13c enriched owing to significant c4 contribution selective preservation of terrestrial relative to marine organic carbon could account for the 13c behavior of toc upon oxidation but only if a 13c depleted component of the bulk terrestrial signal is selectively preserved in the process although the c ntot decrease and positive 15n shift seems inconsistent with selective terrestrial organic preservation results from analysis of a modern eolian dust sample collected in the vicinity indicate these observations are compatible regardless of the specific explanation for these isotopic observations however our findings provide evidence that paleoreconstruction of properties such as pco2 using the 13c of toc is a goal fraught with uncertainty whether or not the marine sedimentary record considered is contaminated with significant terrestrial input nonetheless despite major and selective loss of both marine and terrestrial components as a consequence of postdepositional oxidation intensive organic geochemical proxies such as the alkenone unsaturation index u37k appear resistant to change and thereby retain their paleoceanographic promise

the last 18 kyr fluctuations in norwegian sea surface conditions and implications for the magnitude of climatic change evidence from the north sea a combined record of three cores spanning the last 18 kyr from the northern north sea is investigated for content of benthic and planktonic foraminifera and stable oxygen isotopes the paleoenvironmental development through this time period shows an early deglaciation 18 14 4 ka and the younger dryas 12 7 11 5 ka characterized by arctic polar conditions and increased ice rafting in the norwegian channel during the bolling allerod period warm sea surface temperature 9 c conditions similar to present conditions are inferred while bottom waters stayed cold 0 1 c with normal salinity the bolling allerod period is interrupted twice at 13 9 13 6 ka older dryas and at 13 0 12 8 ka inter allerod cooling period by reductions in sea surface temperatures and increased sea ice cover the beginning of the holocene period is marked by increases in surface and bottom water temperature superimposed on the broad climatic changes through the holocene a series of short lived oscillations in the ocean circulation are recorded the amplitude of these holocene events appears larger in the early holocene prior to 8 ka than compared with the remaining part of the holocene this amplification can possibly be attributed to a general increased freshwater budget in the north atlantic at this time during the final stages of the deglaciation of the laurentide and scandinavian ice sheets

early holocene change in atmospheric circulation in the northern great plains an upstream view of the 8 2 ka cold event elk lake in northwestern minnesota contains numerous proxy records of climatic and environmental change contained in varved sediments with annual resolution for the last 10 000 years these proxies show that about 8200 calendar years ago 8 2 cal ka 7300 radiocarbon years elk lake went froma well stratified lake that was wind protected in a boreal forest to a wellmixed lake in open prairie savanna receiving northwesterly wind blown dust probably from the dry floor of lake agassiz this change in climate marks the initiation of the widely recognized mid holocene altithermal in central north america the coincidence of this change with the so called 8 2 cal ka cold event recognized in ice core and other records fromthe circum north atlantic and thought by some to be caused by catastrophic discharge of freshwater from proglacial lakes agassiz and ojibway suggests that the two events might be related our interpretation of the elk lake proxy records and of other records from less accurately dated sites suggests that change in climate over north america was the result of a fundamental change in atmospheric circulation in response to marked changes in the relative proportions of land water and especially glacial ice in north america during the early holocene this change in circulation probably post dates the final drainage of proglacial lakes along the southern margin of the laurentide ice sheet and may have produced a minor perturbation in climate over greenland that resulted in a brief cold pulse detected in ice cores r 2002 elsevier science ltd all rights reserved

holocene periodicity in north atlantic climate and deep ocean flow south of iceland climate fluctuations during the past millennium are relatively well documented1 on a longer timescale there is growing evidence of millennial scale variability of holocene climate at periodicities of 2 500 and 950 years possibly caused by changes in solar flux 2 3 and 1 500 years maybe related to an internal oscillation of the climate system 4 5 6 but the involvement of deep water masses in these holocene climate changes has yet to be established here we use sediment grain size data from the iceland basin to reconstruct past changes in the speed of deep water flow the study site is under the influence of iceland scotland overflow water isow the flow of which is an important component of the thermohaline circulation that modulates european climate flow changes coincide with some known climate events the little ice age and the mediaeval warm period and extend over the entire holocene epoch with aquasi periodicity of 1 500 years the grain size data indicate afaster isow flow when the climate of northern europe is warmer however a second mode of operation is observed in the early holocene when warm climate intervals are associated with slower isow flow at that time the melting remnant of land based glacial age ice may have provided a sufficient source of fresh water to the ocean to reduce isow flow south of iceland

atmospheric circulation variability in the north atlantic european area since the mid seventeenth century based on monthly mean sea level pressure grids objectively reconstructed by luterbacher et al variations of dynamical modes of the atmospheric circulation for january and july are described by novel indices for running 31 year periods between 1659 and 1999 these indices reflect the continuous evolution of the atmospheric circulation not only with regard to frequency changes of major dynamical modes but also in terms of internal changes within each mode concerning both dynamic vorticity intensity and climatic properties central european temperature and precipitation during occurrence of each mode respectively results indicate the great importance of within mode variations the zonal circulation mode in january varying in frequency with long term cycles primarily changed its dynamic and climatic properties towards higher indices during the transition from the little ice age to modern conditions between 1800 and 1930 within the russian high mode of january a change in preference from easterly to westerly patterns above central europe occurred around 1850 for july a striking frequency maximum of the westerly mode at the end of the eighteenth century coincided with a period of marked summer warmth in central europe due to negative positive deviations in vorticity temperature during occurrence of this mode the long term evolution in july indicates a general increase of anticyclonic conditions strengthening during the last 50 years towards a unique phenomenon within the last centuries the strong increase in the winter time westerly circulation during the last decades however does not appear extraordinary in view of the low frequency variations of this mode

abrupt changes in north american climate during early holocene times recent studies of the greenland ice cores have offered many insights into holocene climatic dynamics at decadal to century timescales1 2 3 despite the abundance of continental records of holocene climate few have sufficient chronological control and sampling resolution to compare with the greenland findings4 butannually laminated sediments varves from lakes can provide high resolution continental palaeoclimate data with secure chronologies here we present analyses of varved sediments from deep lake in minnesota usa trends in the stable oxygen isotope composition of the sedimentary carbonate indicate a pronounced climate cooling from 8 9 to 8 3 kyr before present probably characterized by increased outbreaks of polar air decreased precipitation temperatures and a higher fraction of the annual precipitation falling as snow the abrupt onset of this climate reversal over several decades was probably caused by a reorganization of atmospheric circulation and cooling of the arctic airmass in summer that resulted from the final collapse of the laurentide ice near hudson bay and the discharge of icebergs from the quebec and keewatin centres into the tyrell sea the timing and duration of this climate reversal suggest that it is distinct from the prominent widespread cold snap that occurred 8 200 years ago in greenland and other regions1 5 6 no shifts in the oxygen isotope composition of sediment carbonate occurred at 8 2 kyr before present at deep lake but varve thickness increased dramatically probably as a result of increased deposition of aeolian dust taken together our data suggest that two separate regional scale climate reversals occurred between 9 000 and 8 000 years ago and that they were driven by different mechanisms

a new approach to calculating holocene winter precipitation by combining glacier equilibrium line altitudes and pine tree limits a case stud from hardangerjokulen central southern norway at hardangerjokulen central southern norway detailed knowledge of the number age and magnitude of holocene glacier fluctuations is used to reconstruct variations in equilibrium line altitude ela for the last 10 000 years present and past elas are based on an accumulation area ratio aar of 0 7 and are adjusted for land uplift a synchronous relationship between advanced glacier positions and the highest pine tree limits pinus sylvestris l is demonstrated for the early to mid holocene in southern scandinavia which indicates that warm summers were compensated for by high winter precipitation based on pine tree limit fluctuations as a measure of mean ablation season temperature holocene variations in winter precipitation at hardangerjokulen have been calculated by substitution in the close exponential relationship between mean ablation season temperature and winter precipitation at the ela of norwegian glaciers setting the winter precipitation during the period ad 1961 1990 at 100 mean values

representation of a growth fault in a two dimensional quantitative model abstract a growth fault in a north indonesian basin has been modelled using the two dimensional fluid flow compaction model geopetii the location of the fault and permeability for fluid drive are of primary importance in the fluid pressure distribution in the basin using multiple vertical faults simulations of the fault have been carried out showing the importance of the growth history of the fault in influencing the excess pressure distribution the simulations which yield fluid pressure in agreement with the present day observations suggest that the fault has been dominantly closed to fluid flow since the time of its creation the modelling also led to the conclusion that the fault is not hydrodynamically connected to the surface at the present day but must have been at some time in the past to remove the overpressures developed through undercompaction which are due to the high sedimentation rate of the order of 1000 m ma characterizing the basin models using a single vertical fault suggest that the fault was open to fluid flow in a time interval ranging from 3 5 to 0 5 ma

testing the fidelity of sediment chronology comparison of varve and paleomagnetic results from holocene lake sediments from central finland abstract a careful construction of independent varve and paleomagnetic chronologies from three varved lake sediment records from central finland resulted in detailed and continuous age depth profiles cumulative varve calculation errors were estimated to be 3 for lake alimmainen savijarvi 10 295 340 varve years and 1 for lakes nautajarvi 9898 97 varve years and korttajarvi 9590 103 varve years paleomagnetic secular variation psv curves demonstrate good consistency between these sites and within a margin of varve chronology error they show similar declination and inclination features commonly described in the uk and sweden the timing of psv patterns from finnish varved sites agree well with uk curves between the present and 2000 bc and in pre 6000 bc deposits and with swedish data between the present and 5000 bc combined inclination records from three independently dated finnish varved sites possess an opportunity for accurate paleomagnetic comparisons within the margin of varve chronology errors and throughout the last 10 000 years

simple kinetic models of petroleum formation part iii modelling an open system abstract the movement of petroleum from organic rich source beds to potential carrier beds is the net result of two processes expulsion the release of generated petroleum from kerogen within the source bed and primary migration flow of a petroleum phase through the inorganic void networks of the source bed and all other intervening fine grained rocks expulsion is by far the more important process within the source bed orgas a simple zero dimensional model of the source rock as an open system explicitly models expulsion concurrent with oil and gas generation and oi lgas cracking as a storage threshold problem oil and gas are retained adsorbed absorbed within kerogen until their concentrations exceed the respective sorptive capacity of the residual organic carbon 0 1 and 0 02 g g ck 1 the initial hydrogen index hl 0 controls the important balance between potential sorbate petroleum and sorbant residual carbon using simple geochemical measurements the initial organic carbon is divided into initial oil inert kerogen and oil and gas generative reactive kerogen components reactive kerogens are assigned to one of five global kinetic organofacies with pre determined kinetic parameter sets governing separately rates of oil and gas generation kinetic parameters governing the rates of oil cracking within the source rock are predicted from hl 0 the two most important determinants of source rock behaviour are organofacies and hl 0 at a reference constant heating rate of 2 c ma 1 the projected oil expulsion threshold for typical organofacies members increases in the order a de 100 110 120 135 c f typically expels no oil an order of magnitude increase decrease in heating rate increases decreases these thresholds by ca 15 c typical cumulative gas mass fractions in their ultimate expulsion products are a f 0 25 0 3 0 25 0 65 and 1 0 g g 1 a value of 200 mg hc g c 1 is an approximate minimum hl 0 prerequisite for oil expulsion irrespective of absolute petroleum potential p 0 as a family coals vary dramatically in their expulsion behaviour as their hl 0 ranges both above and velow this value primary migration is efficient for expulsive source rocks movement within the source bed is limited only at low p 0 a source rocks total genetic potential p 0 thickness becomes important during migration outside the source bed it potentially restricts the primary migration distance and the excess of petroleum available for secondary migration and entrapment we evaluate primary migration approximately using a small migration loss factor no more than about 10 saturation of porosity or 1 mg g 1 coupled with an understanding of fluid potential gradients which determine migration direction within the stratigraphic architecture ultimately kerogen degradation and oil to gas cracking in the source rock are the rate limiting processes in petroleum accumulation

low frequency and high frequency changes in temperature and effective humidity during the holocene in south central sweden implications for atmospheric and oceanic forcings of climate an integrated use of independent palaeoclimatological proxy techniques that reflect different components of the climate system provides a potential key for functional analysis of past climate changes here we report a 10 000 year quantitative record of annual mean temperature tann based on pollen climate transfer functions and pollen stratigraphical data from lake flarken south central sweden the pollen based temperature reconstruction is compared with a reconstruction of effective humidity as reflected by a 18o record obtained on stratigraphy of lacustrine carbonates from lake igelsjon c 10 km from lake flarken which gives evidence of pronounced changes in effective humidity the relatively low tann and high effective humidity as reflected by a low evaporation inflow ratio suggest a maritime early holocene climate 10 000 8 300 cal year bp seemingly incompatible with the highly seasonal solar insolation configuration we argue that the maritime climate was due to the stronger than present zonal flow enhanced by the high early holocene sea surface temperatures in the north atlantic the maritime climate mode was disrupted by the abrupt cold event at 8 200 cal year bp followed at 8 000 cal year bp by a stable holocene thermal maximum the latter was characterized by tann values about 2 5 c higher than at present and markedly dry conditions indicative of stable summer time anti cyclonic circulation possibly corresponding with modern blocking anticyclonic conditions the last 4 300 year period is characterized by an increasingly cold moist and unstable climate the results demonstrate the value of combining two independent palaeoclimatic proxies in enhancing the reliability generality and interpretability of the palaeoclimatic results further methodological refinements especially in resolving past seasonal climatic contrasts are needed to better understand the role of different forcing factors in driving millennial scale climate dynamics

new techniques in sediment core analysis an introduction marine sediment cores are the fundamental data source for information on seabed character depositional history and environmental change they provide raw data for a wide range of research including studies of global climate change palaeoceanography slope stability oil exploration pollution assessment and control and sea floor surveys for laying cables pipelines and siting of sea floor structures during the last three decades a varied suite of new technologies have been developed to analyse cores often non destructively to produce high quality closely spaced co located downcore measurements characterizing sediment physical properties geochemistry and composition in unprecedented detail distributions of a variety of palaeoenvironmentally significant proxies can now be logged at decadal and in some cases even annual or subannual scales allowing detailed insights into the history of climate and associated environmental change these advances have had a profound effect on many aspects of the earth sciences particularly palaeoceanography in this paper we review recent advances in analytical and logging technology and their application to the analysis of sediment cores developments in providing access to core data and associated datasets and data mining technology in order to integrate and interpret new and legacy datasets within the wider context of sea floor studies are also discussed despite the great advances in this field however challenges remain particularly in the development of standard measurement and calibration methodologies and in the development of data analysis methods new data visualization tools and techniques need to be developed to optimize the interpretation process and maximize scientific value amplified collaboration environments and tools are needed in order to capitalize on our analysis and interpretation capability of large multi parameter datasets sophisticated yet simple to use searchable internet databases with universal access and secure long term funding and data products resulting in user defined data mining query and display so far pioneered in the usa and australia provide robust models for efficient and effective core data stewardship

a high resolution study of holocene paleoclimatic and paleoceanographic changes in the nordic seas 1 high resolution records from images core md95 2011 in the eastern norwegian sea provide evidence for relatively large and small scale high latitude climate variability throughout the holocene during the early and mid holocene a situation possibly driven by consistent stronger westerlies increased the eastward influence of arctic intermediate and near surface waters for the late holocene a relaxation of the atmospheric forcing resulted in increased influence of atlantic water the main changes in holocene climate show no obvious connection to changing solar irradiance and spectral analysis reveals no consistent signature for any periodic behavior of holocene climate at millennial or centennial timescales there are however indications of consistent multidecadal variability

petroleum systems and hydrocarbon potential analysis of the northwestern uralsk basin nw kazakhstan by utilizing 3d basin modeling methods abstract gas and minor oil production from the northwestern uralsk basin is associated with ttgf caganskaya and darinskaya fields located along a ne sw aligning chain of barrier reefs most important reservoir rocks of the basin are associated with shelf reef pinnacle reef atoll and bar facies of the carbonate complex deltaic or tidal facies of the platform deposits and clastic basinal fan or slope facies the basin comprises multiple petroleum systems characterized by deep marine black shales of paleozoic which shows up to 10 toc the evaluation of these petroleum systems were investigated by utilizing 1 d and 3 d basin models constructed using the geological geophysical and geochemical data the sub salt section of the northwestern uralsk basin demonstrates higher hydrocarbon potential and lower exploration risk compared to the post salt sequence despite the necessity for drilling extreme depths e g over 5000 m particularly in the inner zone various traps associated with salt tectonics favor hydrocarbon accumulations in the artinskian filippovskiy frasnian bobrikovskiy tulskiy and bashkirian proven reservoir rocks among these reservoirs the artinskian filippovskiy is the major oil bearing reservoir rock particularly in the teplovskaya gremiachinskaya and teplovskaya fields it has good hydrocarbon charge access to multiple source rocks besides kungurian salt forms efficient seal on the top among the 15 investigated and modeled source rocks the most expulsive ones are afoninskiy givetian famennian tournaisian tulskiy serpukhovian and vereiskiy which intensively charge reservoirs of the northwestern uralsk basin starting from triassic source to trap timing risk is minimal particularly within the inner and escarpment zones since traps are older gas and oil generation expulsion and migration model results point out a total of 179 mboe gas and 89 mbbl oil potential subsurface conditions associated with gremiachinskaya w teplovskaya teplovskaya tokarevskaya e gremiachinskaya ulianovskaya and tsyganovskaya structures

nature of a regional dogleg pattern in maturity profiles from thrace basin northwestern turkey a newly discovered unconformity or a thermal anomaly vitrinite reflectance ro profiles of the thrace basin are characterized by a regional dogleg pattern corresponding to the depths of ceylan and hamitabat formations we investigated the nature of this dogleg pattern using a one dimensional thermal maturity model by simulating three possible geological scenarios 1 two possible newly discovered unconformities one between the hamitabat and soucak or hamitabat and ceylan formations and the other within the hamitabat formation 2 an abnormal paleoheat flow regime paleothermal kick that developed in the oligocene and extended until the end of the early miocene and 3 a sharp thermal conductivity contrast in the stratigraphic column caused by thermally low conductive deposits of the ceylan formation which act as a regional thermal blanket the sensitivity of each suggested scenario within the model and their effect on the observed dogleg pattern have been examined a comparison of the measured and calculated modeled ro profiles from the proposed scenarios shows that the dogleg pattern can be best explained by a combination of the second paleoheat flow and third scenarios thermal conductivity instead of the unconformity scenario however the discovery of these two newly defined discordance surfaces with the help of well and seismic data requires a significant modification to the chronostratigraphy of the thrace basin the hamitabat karaaa ftepe and gaziky formations and the lower sections of the kean formation are suggested to be time correlative counterparts in a newly constructed chronostratigraphy thus the hamitabat formation can be evaluated as a part of the early middle eocene sequence similar to the gaziky formation in this article we suggest that the hamitabat formation be classified as a group instead of a formation

paleoceanographic reconstructions of surface ocean conditions in the greenland iceland and norwegian seas through the last 14 ka based on diatoms prior reconstructions of the last glacial maximum and the holocene did not include detailed paleoclimate data from the greenland iceland and norwegian gin seas which cover sensitive areas for oceanographic boundaries sea ice distribution and deep water formation in order to fill this gap we studied nine well dated sediment cores from this area and reconstructed the paleoceanographic conditions of the surface gin seas at 2000 year intervals since 13 400 bp based on the diatom record results show that a n s extending sea ice free corridor had opened along norway already at 13 400 bp indicating a northward flow of a branch of the north atlantic drift possibly caused by a change in the jet stream flow due to the decreased height of the north american ice sheet a major change of climatic conditions occurred over the gin seas as the insolation anomaly reached its maximum around 9000 bp when the sea ice cover and the oceanic fronts retreated to a northwesterly position along greenland and the ocean temperatures rose the first half of the holocene is recorded as the warmest period during the last 13 400 bp in the gin seas the duration of this climatic optimum decreased both toward the north and toward the margins of the area the second half of the holocene is characterized by a cooling trend in step with the decreasing insolation these results support the proposal of imbrie et al 1992 that the gin seas region acts as an initial responder to insolation changes