the oligo miocene qom formation iran evidence for an early burdigalian restriction of the tethyan seaway and closure of its iranian gateways in the central iranian esfahan sirjan and qom basins sedimentation of the oligo miocene qom formation took place on extensive mixed carbonate siliciclastic ramps during this time both basins were positioned at the eurasian margin of the tethyan seaway which connected the western and eastern regions of the tethys ocean at least until the late burdigalian during the so called terminal tethyan event the tethyan seaway was then closed due to the collision of the african arabian and iranian eurasian plates facies analysis of the sedimentary record of both basins indicates paleoenvironments ranging from terrestrial to open marine settings including mangrove restricted inner shelf lagoon seagrass meadow reefal and deeper offshore environments recognition of eight depositional sequences and elaboration of an integrated biostratigraphic framework calcareous nannoplankton planktic and larger benthic foraminifers gastropods and pectinids allow us to construct a basin spanning stratigraphy the assignment of the recognized sea level lowstands to the ru 3 to bur 3 lowstands of the global sea level curve enables a comparison with time equivalent sections from the zagros basin which was part of the african arabian plate on the opposing southern margin of the tethyan seaway the so calibrated sections display restrictions of the tethyan seaway and interruption of the south iranian gateways between the qom basin and the proto indopacific in relation to ongoing plate collision during the early burdigalian

mesozoic deep water carbonate deposits from the southern tethyan passive margin in iran pichakun nappes neyriz area biostratigraphy facies sedimentology and sequence stratigraphy the objective of this work is to study the mesozoic turbiditic sediments from the southern tethys margin in iran these sediments are exposed as nappes in the pichakun mountains i e the zagros mountains in the neyriz area which inverted during latest cretaceous time radiolarians are used to both define and date four main lithostratigraphic formations 1 the bar er formation undated probably late triassic to early jurassic 2 the darreh juve formation aalenian early bajocian to middle callovian early oxfordian 3 the imamzadeh formation middle callovian early oxfordian to aptian 4 the neghareh khaneh formation late aptian to turonian coniacian most of the sediments are deep sea gravity flow lobe deposits channel deposits occurred during the bajocian i e the darreh juve fm and deeply incised channels canyons occurred during the albian i e the neghareh khaneh fm twenty seven facies grouped into eight facies associations are defined based on a sequence stratigraphic study i e the stacking pattern five second order cycles 10 30 ma duration defined between two successive distal facies time intervals are characterized 1 the j2 toarcian middle oxfordian unconformity late toarcian aalenian 2 the j3 middle oxfordian berriasian unconformity middle tithonian 3 the k1 1 berriasian undated top 4 the k1 2 undated base early aptian unconformity late hauterivian 5 the k1 3 early aptian at least turonian coniacian unconformity aptian albian boundary the most important tectonic event recorded occurred at the aptian albian boundary a deposition of olistoliths from a few metres to 100 m thick in debris flows related to austrian deformations the arabian scale late toarcian and early tithonian deformations have been recorded as unconformities it is expected that another tectonic event occurred during the late hauterivian the unconformity of cycle k1 1 could be a late valanginian eustatic fall of climatic origin

late cretaceous paleocene formation of the proto zagros foreland basin lurestan province sw iran late cretaceous emplacement of ophiolitic radiolaritic thrust sheets over the arabian passive margin was the first manifestation of the protracted closure of the neotethys ocean which ended with the continental collision between arabia and central iran and the formation of the present zagros fold belt this tectonic stacking produced a flexural basin the amiran basin 400 200 km in size in the northwest zagros that was filled with a 1225 m thick shallowing upward detrital succession made up of the amiran taleh zang and kashkan formations this succession sits unconformably above the late cretaceous gurpi formation and is overlain by the oligocene miocene shahbazan asmari carbonate succession dating of the amiran kashkan succession is based on detailed biostratigraphy using large foraminifera and calcareous nannoplankton the cretaceous tertiary k t boundary is located within the uppermost 25 45 m of the gurpi formation the overlying amiran and taleh zang formations have been dated as paleocene in age however the base of the paleocene within the gurpi formation lacks np1 and np2 zones implying a hiatus of 2 m y at ca 65 5 ma which is inferred to correspond to an early folding phase near the cretaceous paleocene boundary the upper part of the kashkan formation is dated to the earliest eocene by palynostratigraphy a large hiatus or very slow deposition lasting about 15 m y occurs between the kashkan and shahbazan formations in the studied region the base of the prograding shahbazan platform deposits is dated by 87sr 86sr stratigraphy at ca 33 9 ma the upper part of the asmari formation is dated as early middle miocene using foraminifera associations reconstruction of the amiran taleh zang kashkan succession of the amiran basin indicates a thickening of the basin fill from the southern pinch out along the se flank of the kabir kuh anticline to sw of the khorramabad anticline where the flexure is at least 900 m in contrast the ne part of the basin underwent coeval contraction and uplift of 1300 m superimposed smaller undulations onto the large scale flexure are interpreted as late cretaceous paleocene folds regional comparisons se zagros oman and turkey indicate that late cretaceous early tertiary deformation affected the entire ne margin of arabia but that compression was not synchronous being younger in lurestan than in the nw persian gulf where inversion tectonics occurred from turonian to mid campanian times the long sedimentary hiatus spanning most of the middle and late eocene must have been related to deep lithospheric processes linked to the initial events of the protracted closure of the neotethys ocean between arabia and central iran the tectono sedimentary history recorded in the zagros basin may help to understand early foreland basin growth in other orogens in which subsequent continental collision has obliterated these early events

late oligocene miocene mid latitude aridification and wind patterns in the asian interior the asian interior has the largest mid latitude arid zone in the northern hemisphere and so has become increasingly attractive for studying the initiation and the past extent of aridification in this zone given the enormousness of the asian interior it remains unclear how old and extensive the eolian deposits might have been and what wind regimes have been responsible for the formation of the mid latitude arid zone here we report new eolian records of widespread tertiary eolian deposits in a region far from the chinese loess plateau the giant junggar inland basin of northwestern china our results demonstrate that the earliest eolian deposition initiated ca 24 ma we interpret that the tertiary eolian dust in the junggar basin was transported by westerly winds possibly from areas in kazakhstan the dust differs from the airborne dust transported by winter monsoon winds from the deserts of mongolia and northern china that accumulated on the loess plateau these results further reveal that the climate pattern similar to that of the present has prevailed at least since the latest oligocene in central asia

middle to late cenozoic basin evolution in the western alborz mountains implications for the onset of collisional deformation in northern iran carbonates and basalt flows yielding 40 ar 39 ar ages of 32 7 0 3 and 32 9 0 2 ma the gand ab unit is correlated with the oligocene lower miocene qom formation of central iran and is considered a product of thermal subsidence following eocene extension the narijan unit unconformably overlies the gand ab unit and is composed of fluvial lacustrine and alluvial fan sediments exhibiting contractional growth strata we correlate the narijan unit with the middle to upper miocene upper red formation of central iran on the basis of lithofacies similarities stratigraphic position and an 8 74 0 15 ma microdiorite dike 40 ar 39 ar that intruded the basal strata deformation timing is constrained by crosscutting relationships and independent thermochronological data the parachan thrust system along the eastern edge of the ancestral taleghan alamut basin is cut by dikes dated at 8 74 0 15 ma to 6 68 0 07 ma 40 ar 39 ar subhorizontal gravels that unconformably overlie tightly folded and faulted narijan strata are capped by 2 86 0 83 ma 40 ar 39 ar andesitic lava flows these relationships suggest that alborz deformation had migrated southward into the taleghan alamut basin by late miocene time and shifted to its present location along the active range front by late pliocene time data presented here demonstrate that shortening in the western alborz mountains had started by late middle miocene time this estimate is consistent with recent thermochronologicalresultsthatplacetheonsetofrapid exhumation in the western alborz at 12 ma moreover nearly synchronous miocene contraction in the alborz zagros mountains turkish iranian plateau and anatolia suggests that the arabia eurasia collision affected a large region simultaneously without a systematic outward progression of mountain building away from the collision zone citation guest b b k horton g j axen j hassanzadeh and w c mcintosh 2007 middle to late cenozoic basin evolution in the western alborz mountains implications for the onset of collisional deformation in northern iran tectonics 26 tc6011 doi 10 1029 2006tc002091

40ar39ar ages and tectonic setting of ophiolite from the neyriz area southeast zagros range iran abstract an ophiolite considered to be an allochthonous fragment of tethyan oceanic crust and mantle crops out near neyriz in the zagros range iran 40 ar 39 ar ages ranging from 76 8 23 8 ma to 105 23 3 ma were measured on hornblende from five samples of plagiogranite and diabase from the ophiolite the most precise ages are 85 9 3 8 ma for a diabase and 83 6 8 4 ma for a plagiogranite the weighted mean age of hornblende from the five samples is 87 5 7 2 ma which indicates that the igneous part of the neyriz ophiolite formed during the early part of the late cretaceous pargasite from amphibolite below peridotite of the neyriz ophiolite has a 40 ar 39 ar age of 94 9 7 6 ma the pargasite age agrees within analytical uncertainty with the ages measured on diabase and plagiogranite comparable ages have been measured on igneous rocks from the samail ophiolite of oman and on amphibolite below peridotite of the samail ophiolite

formation of internally drained contractional basins by aridity limited bedrock incision 1 low internal relief aridity and internal drainage characterize the puna altiplano plateau and the tibetan plateau and the tarim basin structurally these areas are reverse fault bounded terrains with intervening wedge top basins that store thick accumulations of sediment for millions of years orographic barriers along the margins of these basins are oriented normal to moisture bearing winds resulting in regional aridity the combination of this aridity rapid shortening and uplift rates and resistant exposed lithologies coincides with the location of these internally drained basins we hypothesize that these large internally drained areas persist indefinitely when uplift overwhelms the fluvial systems and defeats the channel network to test this hypothesis we developed models of channel defeat to examine the threshold conditions required to fragment the channel network the results of these models suggest that low erodibility rocks moderate to high uplift rates and low precipitation favor defeat of orogen traversing channels most coupled tectonic landscape development models prevent the development of internal drainage and so may overestimate the voracity of erosion in regimes that favor internal drainage profoundly influencing predicted orogenic growth patterns

timing of thrust activity in the high zagros fold thrust belt iran from u th he thermochronometry 1 apatite and zircon u th he cooling ages are used to quantify the timing of exhumation associated with thrust faulting in the high zagros fold thrust belt single grain cooling age data were collected from 1 cambrian sandstone in various thrust sheets 2 sandstone and basement clasts derived from structurally controlled salt plugs or fault bounded slices and 3 syntectonic neogene siliciclastics strata in the northwestern kuhrang and central kuh e lajin high zagros apatite u th he ahe ages range from 26 7 to 0 38 ma most cooling and exhumation occurred in the early to middle miocene constrained by ahe ages 19 15 ma from the high zagros thrust sheet localized faults and reset cooling ages from bakhtiyari deposits in the southeastern high zagros kuh e dinar cooling occurred later with ahe ages ranging from 16 5 to 0 79 ma here most cooling and exhumation occurred in the late miocene constrained by ahe ages 12 8 ma from the high zagros fault and exhumed paleozoic clasts in synorogenic strata zircon u th he zhe ages from bedrock samples across the high zagros are reflective of the precollisional thermal history the preservation of precollisional zhe ages limits the pre miocene maximum burial temperature of the exhumed strata to 180 c and indicate 7 9 km of maximum exhumation in the central zagros this study shows that thrust activity in the high zagros and continental suturing along the zagros suture was underway by at least 19 ma and initiated no later than latest oligocene to early miocene time 23 ma

cenozoic evolution of neotethys and implications for the causes of plate motions africa north america eurasia plate circuit rotations combined with red sea rotations and new estimates of crustal shortening in iran define the cenozoic history of the neotethyan ocean between arabia and eurasia the new constraints indicate that arabia eurasia convergence has been fairly constant at 2 to 3 cm yr since 56 ma with slowing of africa eurasia motion to 1 cm yr near 25 ma coeval with the opening of the red sea ocean closure occurred no later than 10 ma and could have occurred prior to this time only if a large amount of continental lithosphere was subducted suggesting that slowing of africa significantly predated the arabia eurasia collision these kinematics imply that africa s disconnection with the negative buoyancy of the downgoing slab of lithosphere beneath southern eurasia slowed its motion the slow steady rate of northward subduction since 56 ma contrasts with strongly variable rates of magma production in the urumieh dokhtar arc implying magma production rate in continental arcs is not linked to subduction rate

dynamic constraints on the crustal scale rheology of the zagros fold belt iran thin skinned fold and thrust belts are generally considered as the result of contractional deformation of a sedimentary succession over a weak decollement layer the resulting surface expression frequently consists of anticlines and synclines spaced in a fairly regular manner it is thus tempting to use this spacing along with other geological constraints to obtain insights into the dynamics and rheology of the crust on geological time scales here we use the zagros mountains of iran as a case study as it is one of the most spectacular well studied thin skinned fold and thrust belts in the world both analytical and numerical models are employed to study what con trols fold spacing and under what conditions folding dominates over thrusting the models show that if only a single basal decollement layer is present underneath a brittle sedimentary cover deformation is dominated by thrusting which is inconsistent with the data of the zagros fold belt if we instead take into account additional decollement layers that have been documented in the fi eld a switch in deformation mode occurs and crustal scale folding is obtained with the correct spacing and time scales we show that fold spacing can be used to constrain the friction angle of the crust which is 5 the zagros fold belt this implies that on geological time scales the upper crust is signifi cantly weaker than previously thought possibly due to the effect of fl

tertiary sequence of deformation in a thin skinned thick skinned collision belt the zagros folded belt fars iran 1 we describe how thin skinned thick skinned deformation in the zagros folded belt interacted in time and space homogeneous fold wavelengths 15 8 5 3 km tectono sedimentary evidence for simultaneous fold growth in the past 5 5 2 5 ma drainage network organization and homogeneous peak differential stresses 40 15 mpa together point to buckling as the dominant process responsible for cover folding basin analysis reveals that basement inversion occurred 20 ma ago as the arabia eurasian plate convergence reduced and accumulation of neogene siliciclastics in foreland basin started by 10 ma ongoing contraction occurred by underplating of arabian crustal units beneath the iranian plate this process represents 75 of the total shortening it is not before 5 ma that the zagros foreland was incorporated into the southward propagating basement thrust wedge folds rejuvenated by 3 2 ma because of uplift driven by basement shortening and erosion since then folds grew at 0 3 0 6 mm yr and forced the rivers to flow axially a total shortening of 65 78 km 16 19 is estimated across the zagros this corresponds to shortening rates of 6 5 8 km ma consistent with current geodetic surveys we point out that although thin skinned deformation in the sedimentary cover may be important basement involved shortening should not be neglected as it requires far less shortening moreover for such foreland folded belts involving basement shortening underplating may be an efficient process accommodating a significant part of the plate convergence

constraints on palaeodrainage evolution induced by uplift and exhumation on the southern flank of the zagros iranian plateau foreland sedimentary rocks from the northern fars region of iran contain a record of deformation associated with the cenozoic collision between arabia and eurasia that resulted in formation of the zagros orogen the timing of the deformation associated with this event is poorly known to address this we conducted a study of miocene foreland sedimentary rocks 19 7 14 8 ma of the chahar makan syncline using clast composition clay mineralogy and low temperature fission track dating the results showed that most of the sedimentary rocks were sourced from ophiolitic rocks detrital apatite fission track aft age signatures of miocene sedimentary rocks record exhumation in the hanging wall of the main zagros thrust and confirm that the change from underthrusting of the stretched arabian margin to widespread crustal thickening and deformation in the zagros region is no younger than 19 7 ma a transition from late oligocene to mesozoic eocene aft detrital age signatures between 19 7 16 6 ma and 16 6 13 8 ma is interpreted to reflect a possible rearrangement of palaeodrainage distribution that resulted from folding and expansion uplift of the zagros iranian plateau region supplementary material details of the succession of the study area a complete presentation of sample preparation and fission track age measurements of apatite grains and examples of x ray diffractograms are available at http www geolsoc org uk sup18502

the present day deformation of the central zagros from gps measurements 1 in 1997 and in 2000 we measured the distances between 14 geodetic benchmarks across the central zagros mountain belt the results show that about 10 mm yr of shortening in the central zagros is distributed across the mountain belt this shortening corresponds to roughly 50 of the total convergence between arabia and eurasia and is consistent in direction the persian gulf does not deform significantly the main zagros reverse fault is not an active kinematic boundary the internal deformation of the folded belt is rather homogeneous at the scale of our survey which does not allow us to detect any individual active blind fault however the strain pattern suggests that n s dextral strike slip faults may accommodate part of the deformation

plate tectonic evolution of the southern margin of eurasia in the mesozoic and cenozoic abstract thirteen time interval maps were constructed which depict the triassic to neogene plate tectonic configuration paleogeography and general lithofacies of the southern margin of eurasia the aim of this paper is to provide an outline of the geodynamic evolution and position of the major tectonic elements of the area within a global framework the hercynian orogeny was completed by the collision of gondwana and laurussia whereas the tethys ocean formed the embayment between the eurasian and gondwanian branches of pangea during late triassic early jurassic times several microplates were sutured to the eurasian margin closing the paleotethys ocean a jurassic cretaceous north dipping subduction boundary was developed along this new continental margin south of the pontides transcaucasus and iranian plates the subduction zone trench pulling effect caused rifting creating the back arc basin of the greater caucasus proto south caspian sea which achieved its maximum width during the late cretaceous in the western tethys separation of eurasia from gondwana resulted in the formation of the ligurian penninic pieniny magura ocean alpine tethys as an extension of middle atlantic system and a part of the pangean breakup tectonic system during late jurassic early cretaceous times the outer carpathian rift developed the opening of the western black sea occurred by rifting and drifting of the western central pontides away from the moesian and scythian platforms of eurasia during the early cretaceous cenomanian the latest cretaceous paleogene was the time of the closure of the ligurian pieniny ocean adria alcapa terranes continued their northward movement during eocene early miocene times their oblique collision with the north european plate led to the development of the accretionary wedge of the outer carpathians and its foreland basin the formation of the west carpathian thrusts was completed by the miocene the thrust front was still propagating eastwards in the eastern carpathians during the late cretaceous the lesser caucasus sanandaj sirjan and makran plates were sutured to the iranian afghanistan plates in the caucasus caspian sea area a north dipping subduction zone jumped during paleogene to the scythian turan platform the shatski terrane moved northward closing the greater caucasus basin and opening the eastern black sea the south caspian underwent reorganization during oligocene neogene times the southwestern part of the south caspian basin was reopened while the northwestern part was gradually reduced in size the collision of india and the lut plate with eurasia caused the deformation of central asia and created a system of nw se wrench faults the remnants of jurassic cretaceous back arc systems oceanic and attenuated crust as well as tertiary oceanic and attenuated crust were locked between adjacent continental plates and orogenic systems

late cenozoic and modern stress fields in the western fars iran implications for the tectonic and kinematic evolution of central zagros 1 the zagros iran developed during mio pliocene times in response to arabia eurasia convergence the western fars highlights a major bend of the deformation front and displays a remarkable set of nearly n s right lateral strike slip faults the kazerun borazjan karebass sabz pushan sarvestan faults oblique at high angle to the belt the region likely plays a major kinematic role by accommodating the change in shortening modes from partitioned in the western central zagros to nonpartitioned in the eastern zagros the inversion of focal mechanisms from small and moderate earthquakes shows a consistent n020 030 compression with a low ratio between differential stresses this regime accounts for the combination of strike slip and thrust type mechanisms through likely 2 3 permutations fault slip analysis reveals two successive late cenozoic regional compressional trends ne sw then n020 the latter is in good agreement with the present day stress the significance of the ne sw compression is discussed alternatively in terms of stress deviations or block rotations in relation to the strike slip fault system fieldwork and satellite imagery suggest that these faults behave first as transfer faults during folding of the cover and later as strike slip faults in agreement with the succession of stress regimes and the evolution of the dominant deformation style from thin skinned to thick skinned the first order stability of the collision related state of stress since 5 ma supports that the arabia eurasia convergence did not give rise to partitioning in the western fars but rather was and is still accommodated by distributed deformation involving both shortening and strike slip motion throughout the cover and the basement

oroclinal bending distributed thrust and strike slip faulting and the accommodation of arabia eurasia convergence in ne iran since the oligocene regional shortening is accommodated across ne iran in response to the collision of arabia with eurasia we examine how n s shortening is achieved on major thrust systems bounding the eastern branch of the alborz east of 57 e sabzevar and kuh e sorkh mountain ranges which lie south of the kopeh dagh mountains in ne iran although these ranges have experienced relatively few large earthquakes over the last 50 yr they have been subject to a number of devastating historical events at neyshabur esfarayen and sabzevar a significant change in the tectonics of the eastern alborz occurs directly south of the central kopeh dagh near 57 e to the east shortening occurs on major thrust faults which bound the southern margin of the range resulting in significant crustal thickening and forming peaks up to 3000 m high active shortening dies out eastward into afghanistan which is thought to belong to stable eurasia the rate of shortening across thrust faults bounding the south side of the eastern alborz north of neyshabur is determined using optically stimulated luminescence dating of displaced river deposits and is likely to be 0 4 1 7 mm yr 1 shortening across the sabzevar range 150 km west of neyshabur has previously been determined at 0 4 0 6 mm yr 1 although reassessment of the rate here suggests it may be as high as 1 mm yr 1 migration of thrust faulting into foreland basins is common across ne iran especially in the esfarayen region near 57 e where the northward deflection of the east alborz range reaches a maximum of 200 20 km from its presumed linear e w strike at the beginning of the oligocene west of 57 e the tectonics of the alborz are affected by the westward motion of the south caspian region which results in the partitioning of shortening onto separate thrust and left lateral strike slip faults north and south of the range at the longitude of 59 e published gps velocities indicate that 50 per cent of the overall shortening across ne iran is accommodated in the kopeh dagh the remaining 50 per cent regional shortening must therefore be accommodated south of the kopeh dagh in the eastern alborz and kuh e sorkh ranges assuming present day rates of slip and the fault kinematics are representative of the late cenozoic deformation in ne iran the total 200 20 km n s shortening across the eastern alborz and kopeh dagh mountains since the beginning of uplift of the kopeh dagh basin would be accommodated in 30 8 ma although this extrapolation may be inappropriate over such a long timescale the age is nevertheless consistent with geological estimates of post early to middle oligocene 30 ma for the onset of kopeh dagh uplift

paleoenvironmental significance of clay mineral associations at the cretaceous tertiary passage abstract the clay mineral stratigraphy at the cretaceous tertiary transition is considered by the study of new sections walvis ridge maud rise central italy northern tunisia which are compared with results of previous investigations increased contents of smectite and or kaolinite or substrate derived species e g illite group depending on the areas investigated are observed near the boundary these diversified modifications indicate increased erosion and predominance of local detrital supply including that of volcanic rocks over general related causes most probably these modifications of clay mineral associations express a major geodynamic disruption characterized by tectonic instability and sea level drop those events began prior to the cretaceous tertiary boundary i e prior to the major iridium anomaly recorded in sediments this could explain why a catastrophic event at the cretaceous tertiary boundary is hardly evidenced in the clay sedimentological record which is extremely sensitive to the global changes in the earth s terrestrial environment

moisture asymmetry and mjo eastward propagation in an aquaplanet general circulation model abstractthe role of zonal moisture asymmetry in the eastward propagation of the madden julian oscillation mjo is investigated through a set of aquaplanet atmospheric general circulation model agcm experiments with a zonally symmetric sea surface temperature distribution in the control experiment the model produces eastward propagating mjo like perturbations with a dominant period of 30 90 days the model mjo exhibits a clear zonal asymmetry in the lower tropospheric specific humidity field with a positive negative anomaly appearing to the east west of the mjo convection a diagnosis of the lower tropospheric moisture budget indicates that the asymmetry primarily arises from vertical moisture advection associated with boundary layer convergence while horizontal moisture advection has the opposite effect in a sensitivity experiment the lower tropospheric specific humidity field is relaxed toward a zonal mean basic state derived from the control simulation in this case the model s mean state r

middle to late miocene middle eastern climate from stable oxygen and carbon isotope data southern alborz mountains n iran abstract the alborz mountains of northern iran intercept and divert the northern hemisphere westerlies carrying moisture from the mediterranean and black sea and form an orographic barrier to moisture sourced to the north in the caspian sea this implies that terrestrial deposits along the southern alborz mountains leeward side of northerly winds and windward side of westerlies with the respect to tibet and other mountainous terrain in the himalayan karakoram realm potentially track changes in past moisture and erosional regimes and mirror rainfall patterns here we present results of a stable isotope analysis and clay mineral study of the miocene ca 17 5 7 6 ma upper red formation in the foreland of the southern alborz mountains the changes recorded by stable oxygen and carbon isotope data from pedogenic and lacustrine palustrine carbonate in the southern alborz mountains suggest 1 an increase in aridity possibly related to the evolution of the alborz orographic rain shadow which became more efficient between 17 5 and 13 2 ma 2 a steady increase in precipitation between 13 2 and 10 3 ma with a significant increase in rainout along the southern slope of the alborz mountains between 11 and 10 3 ma possibly related to perturbations in atmospheric circulation pattern in the northern hemisphere as suggested by coeval wetter phases in southern europe and 3 a decrease in aridity from ca 9 6 to 7 6 ma possibly reflecting an increase in the seasonality of precipitation based on environmental and climatic changes observed across southern asia and india starting from ca 10 ma we speculate that the topographic evolution of the himalayan tibetan system might have affected the late miocene climate in middle east

what triggers the transition of palaeoenvironmental patterns in china the tibetan plateau uplift or the paratethys sea retreat abstract geological research has illustrated the transition of palaeoenvironmental patterns by the earliest miocene from a planetary wind dominant type to a monsoon dominant type indicating that the east asian monsoon became markedly intensified and played a leading role in the east asian climate from a modeling point of view the pioneering research using the reduced number of scenarios had demonstrated that both the tibetan plateau uplift and the paratethys sea retreat were important for understanding the asian monsoon evolution however the sensitivity of the paratethys retreat to the east asian climate still needs further studies based on the more detailed scenarios thirty numerical experiments under the six paratethys sea and the five tibetan plateau conditions illustrate the shifts from zonal climate to the monsoon climate in east asia the results confirm again that both the paratethys retreat and the tibetan plateau uplift play important roles in the formation of the monsoon dominant environmental pattern and show that the paratethys retreat can strengthen the east asian monsoon and greatly increase humidity and aridity respectively in the monsoon areas and northwest china which is similar to the impact of the tibetan plateau uplift on the east asian climate furthermore the fact that the paratethys sea retreats to the turan plate is found to be the key criterion for the palaeoenvironmental patterns transition in china the shrinkage of paratethys sea leads to the reconstructions of the pressure system and the atmospheric circulations which result in the variations of precipitation and the transition of palaeoenvironmental patterns

oligocene and early miocene coral faunas from iran palaeoecology and palaeobiogeography oligocene and early miocene coral assemblages from three sections of central iran are investigated with respect to their palaeoecological and palaeobiogeographic implications these corals are compared with faunas from the mediterranean tethys and the indopacific associated larger foraminifers are used for biostratigraphy and to support the palaeoecological interpretation the studied sections are situated in the foreland basins of the iranian plate which is structured into a fore arc and a back arc basin separated by a volcanic arc the coral assemblages from abadeh indicate a shallowing upward trend infrequently distributed solitary corals at the base of the section indicate a turbid environment above a distinct horizon characterised by a leptoseris stylophora assemblage associated with lepidocyclinids and planktonic foraminifers is interpreted as maximum flooding surface small patch reefs with a porites faviidae assemblage are a common feature of late oligocene to early miocene coral occurrences and indicate water depths of less than 20 m the diversity of the coral faunas shows marked differences oligocene corals from the esfahan sirjan fore arc basin comprise more than 45 species of 32 genera and occur in a wide range of environments early miocene corals from the qom back arc basin are less frequent show a lower diversity 13 genera with 15 species and occur in single horizons or small patch reefs

seismic imaging of the lithospheric structure of the zagros mountain belt iran we present a synthesis and a comparison of the results of two temporary passive seismic experiments installed for a few months across central and northern zagros the receiver function analysis of teleseismic earthquake records gives a high resolution image of the moho beneath the seismic transects on both cross sections the crust has an average thickness of 43 2 km beneath the zagros fold and thrust belt and the central domain the crust is thicker beneath the hanging wall of the main zagros reverse fault mzrf with a larger maximum moho depth in central 69 2 km than in northern zagros 56 2 km the thickening affects a narrower region 170 km beneath the sanandaj sirjan zone of central zagros and a wider region 320 km in northern zagros we propose that this thickening is related to overthrusting of the crust of the arabian margin by the crust of central iran along the mzrf considered as a major thrust fault cross cutting the whole crust the fault is imaged as a lowvelocity layer in the receiver function data of the northern zagros profile moreover the crustal scale thrust model reconciles the imaged seismic moho with the bouguer anomaly data measured on the central zagros transect at upper mantle depth p wave tomography confirms the previously observed strong contrast between the faster velocities of the arabian margin and the lower velocities of the iranian micro blocks our higher resolution tomography combined with surface wave analysis locates the suture in the shallow mantle of the sanandaj sirjan zone beneath central zagros the arabian upper mantle has shield like shear wave velocities while the lower velocities of the iranian upper mantle are likely due to higher temperature but these velocities are not low enough and the low velocity layer not thick enough to conclude on a delamination of the lithospheric mantle lid beneath iran the lack of a high velocity anomaly in the mantle beneath central iran suggests that the neotethyan oceanic lithosphere is probably detached from the arabian margin

comparisons of the kinematics and deep structures of the zagros and himalaya and of the iranian and tibetan plateaus and geodynamic implications 1 we compare the geologic histories the deep structures and the present day kinematics of deformation of the himalaya and the adjacent tibetan plateau with those of the zagros and iranian plateau to test geodynamic processes of continental collision shortly after india and arabia collided with eurasia horizontal shortening manifested itself by folding and thrust faulting of sedimentary rock detached from india s and arabia s underlying crystalline basement subsequently slip on thrust faults stacked slices of india s basement to build the himalaya on india s northern margin such faulting has not yet developed in the zagros where collision is more recent and arabia penetrates into eurasia more slowly than india does so that postcollision convergence with eurasia is less the greater elevation thicker crust and more marked heterogeneity of the upper mantle beneath the tibetan than beneath the iranian plateau also reflect a more advanced stage of development moreover while thrust or reverse faulting and crustal shortening continue on the margins of both plateaus normal faulting suggesting horizontal extension and crustal thinning occurs within tibet but not in iran hence the balance of forces that built the high tibetan plateau must have changed apparently some time since 15 ma removal of tibetan mantle lithosphere could have altered that balance if mantle lithosphere beneath the iranian plateau has been removed however the change in force balance has been too small to initiate normal faulting low seismic wave speeds in the uppermost mantle just beneath the moho of both plateaus suggest to us that lithosphere beneath both is thin consistent with late cenozoic removal of it but alternative explanations might account for these low speeds despite its apparently thin and hence presumably weak mantle lithosphere much of central iran undergoes little deformation it illustrates how a crustal block can behave rigidly not necessarily because it is strong but because deviatoric stresses can be small whereas differences between the two regions clearly depend on the amount that arabia and india have penetrated into eurasia which scales with both the dates of collision and rates of convergence we see no differences in the operative processes that depend on the present day rates of convergence

tectonic control on sedimentary facies pattern and sediment accumulation rates in the miocene foreland basin of the southern alborz mountains northern iran 1 the southern alborz mountains of northern iran are an integral part of the arabia eurasia collision zone a magnetostratigraphic and rock magnetic investigation of the eyvanekey stratigraphic section in the southern alborz mountains reveals the spatiotemporal character of sedimentary facies migration in the alborz foreland basin the section constitutes three coarsening upward units units 1 2 and 3 comprising the upper red and hezardarreh formations our data reveal that the upper red formation was deposited between 17 5 and 7 5 ma while the depositional age of the top of the hezardarreh formation can be extrapolated to 6 2 ma slow sediment accumulation rates correlate with sedimentary facies comprising prograding coarsening upward units this is likely the result of intraforeland uplift units 1 and 2 and basin inversion probably associated with a growth syncline located in the proximal foreland unit 3 in contrast fine grained strata at the bottom of each cycle are associated with faster sediment accumulation rates testifying to enhanced flexural basin subsidence in the course of thrust loading progradation of coarse grained facies also occurred during relatively fast sediment accumulation top of unit 2 suggesting that the influx of coarse grained sediment outpaced the storage capacity of the proximal foreland thus despite an overall southward propagation of deformation into the southern alborz foreland the locus of active deformation must have migrated back and forth on a time scale of circa 0 7 to 2 ma

constraints on arabian plate motion and extensional history of the red sea analysis of the geologic and geophysical data from the western and northern margin of the arabian plate combined with data from the red sea gulf of aden leads to an interpretation of arabian plate motion that supports an episodic extensional history in the red sea and gulf of aden phase 1 extension began in medial to late eocene and was caused by the nw propagation of the reoriented central indian ridge spreading center it stretched and thinned continental crust along numerous wrench and normal faults that reactivated preexisting structures first phase extension stopped when the arabian plate terminally sutured to eurasia in the medial miocene and halted northward movement of arabia relative to africa the combined african arabian plates moved north more slowly constricting and thickening continental crust in the bitlis zagros sutures while the red sea remained technically quiescent and accumulated salt by the early pliocene continued northward movement was accommodated by lateral extrusion of large continental wedges north of the bitlis zagros sutures this allowed arabia to move northward faster than africa and reopen the red sea where phase 2 extension was expressed by seafloor spreading extension within the red sea gulf of aden rift system has been controlled by the interactions and effects of two factors 1 convergent processes between the north margin of the arabian plate and the eurasian plate to the north and 2 northwest propagation of extension associated with the medial eocene reorganization of the central indian spreading center

heavy metal pollution in the surrounding ore deposits and mining activity a case study from koyulhisar sivas turkey the oxidation of sulfide minerals generates acidic waters containing high levels of so4 and fe the study area has active pb zn cu mining it is thought that the surface subsurface underground sulfide minerals in the region generally contribute to the acidification of groundwater low ph values are also responsible for dissolved metals al fe mn so4 pb zn in the groundwater and river furthermore current mining wastes have affected concentrations of trace elements in the water high fe and mn concentrations are generally found in the spring which has acidic and low eh values while al fe and mn concentrations in the acidic waters show notable increases with the maximum values reaching 8 829 19 084 and 1 708 ppb respectively these values exceed the turkish drinking water standard of 200 200 and 50 ppb respectively

constraints on miocene oceanography and climate in the western and central paratethys o sr and nd isotope compositions of marine fish and mammal remains abstract the paratethys evolved as a marginal sea during the alpine himalayan orogeny in the oligo miocene sediments from the northern alpine molasse basin the vienna and the pannonian basins located in the western and central part of the paratethys thus provide unique information on regional changes in climate and oceanography during a period of active alpine uplift oxygen isotope compositions of well preserved phosphatic fossils recovered from the sediments support deposition under sub tropical to warm temperate climate with water temperatures of 14 to 28 c for the miocene 18o values of fossil shark teeth are similar to those reported for other miocene marine sections and using the best available estimates of their biostratigraphic age show a variation until the end of the badenian similar to that reported for composite global record the 87sr 86sr isotope ratios of the fossils follow the global miocene seawater trend albeit with a much larger scatter the deviations of 87sr 86sr in the samples from the well constrained seawater curve are interpreted as due to local input of terrestrially derived sr contribution of local sources is also reflected in the end values consistent with input from ancient crystalline rocks e g bohemian massif and or mesozoic sediments with end 7 excluding samples showing local influence on the water column an average end value of 7 9 0 5 may be inferred for the miocene paratethys this value is indistinguishable from the end value of the contemporaneous indian ocean supporting a dominant role of this ocean in the western and central paratethys

convergence history across zagros iran constraints from collisional and earlier deformation the zagros orogen provides a unique opportunity within the alpine system to evaluate the interplay between a young tertiary collision and earlier subduction obduction processes within the crush zone and the sanandaj sirjan internal zone separating the zagros fold belt from central iran we document several major tectonic events taking place at the end of the cretaceous of the eocene and from the mio pliocene onwards ca 20 15 ma contrary to recent interpretations our data cross sections and description of the overall deformation style strongly suggest that the main zagros thrust mzt is deeply rooted possibly to moho depths and that the suture zone effectively runs along the mzt field observations show that the final resorption of the oceanic domain took place slightly after 35 ma and that collision must have started before ca 23 25 ma in northern zagros the shortening rate across the crush zone since the mid miocene 20 15 ma is estimated at a minimum 3 4 mm year shear movements in the crush zone during the eocene oligocene period and extensional strike slip movements in the internal zones during the late cretaceous point to an oblique setting early in the convergence history a geotectonic scenario for convergence from the time of obduction to the present is finally proposed

calcite twinning constraints on late neogene stress patterns and deformation mechanisms in the active zagros collision belt mechanically induced calcite twins in veins and host rocks of late cretaceous to miocene age in iran have been used to determine regional arabia eurasia collisional stresses a late folding stress regime with a compression oriented 025 15 has been identified across the zagros belt and the southern iranian plateau this late neogene stress pattern agrees with the current stress field determined from the focal mechanisms of basement earthquakes and suggests that the hormuz salt decollement poorly decouples the basement and cover stress fields our data show that the collisional state of stress has been relatively constant since ca 5 ma the magnitudes of the stresses obtained from the twinning analysis are unexpectedly low and to a first approximation they are constant across the zagros simply folded belt this result supports an overall mechanism of buckling of the detached zagros cover internal viscous plastic processes help to relieve stress within this cover thus lowering its seismogenic potential beyond these regional implications this study underlines the potential of paleostress analyses in constraining both the tectonics and the mechanics of ancient and active foreland fold belts

the eocene bimodal piranshahr massif of the sanandaj sirjan zone nw iran a marker of the end of the collision in the zagros orogen abstract the bimodal piranshahr massif is composed of coeval but geochemically unrelated mafic 40 7 0 2 ma zircon u pb sensitive high resolution ion microprobe shrimp age and a type felsic rocks 41 0 5 ma rb sr and 41 3 0 8 ma zircon u pb shrimp age the mafic rocks consist of two geochemical types of gabbros that derived from different magmas the more abundant gabbros are moderately alkaline have ratios of large ion lithophile elements to ree and high field strength elements to ree similar to those of intraplate mantle magmas 87 sr 86 sr 41 ma 0 7036 and e nd 41 ma 7 2 the less abundant gabbros have calc alkaline affinities 87 sr 86 sr 41 ma 0 7043 and e nd 41 ma 4 78 felsic rocks are metaluminous a2 type annite fayalite hedenbergite hypersolvus leucocratic coarse grained agpaitic syenites pulaskites and granites with 87 sr 86 sr 41 ma 0 7048 and e nd 41 ma 3 6 4 5 syenites pulaskites and granites are genetically related pulaskites probably represent alkali enriched water rich residual melts from which an f rich vapour phase was later separated granites were probably generated during open system processes in which f rich hydrous alkaline fluids released from the syenites acted upon pre existing felsic rocks the c 41 ma age of the post collisional piranshahr massif indicates that the related collision probably occurred at 50 60 ma i e late palaeocene or early eocene thus resolving a much debated question

tectono metamorphic evolution of the neyriz metamorphic complex quri kor e sefid area sanandaj sirjan zone sw iran abstract the neyriz region includes outcrops of metamorphic rocks that are thrust over the neotethyan ophiolites these rocks are affected by a major deformational event the result of which includes a shearing polyphase foliation present in gneissic core domes overprinted by a crenulation cleavage these fundamental structures developed contemporaneously with a medium pressure metamorphism which is characterized by the syn kinematic crystallization of kyanite and the beginning of anatexis followed by the development of retrometamorphic mineral parageneses the major deformation phase in the area occurred during the early cimmerian orogeny in the late triassic following the orogeny the gneiss domes started to rise into the upper levels of the crust from the geodynamic point of view after the mid permian the studied area was situated at southern passive margin of the iranian plate the central iranian microcontinent at that time was separated by the neotethys ocean from the gondwanian supercontinent after the late triassic the region became an active margin associated with an accretionary prism the margin was finally involved in an orogenic wedge after the closure of the neotethyan oceanic basin in the late mesozoic closure of the basin resulted in a major thrusting of the metamorphic rocks of the southern iranian margin over the neotethyan ophiolites

mineralogical geochemical and isotopic evolution of two miocene mafic intrusions from the zagros iran abstract in the zagros mountain belt which represents in iran the collision zone between eurasian and arabian african plates large plutonic intrusions were emplaced during miocene times these massifs are composed of layered cumulates with sequences of fine grained texturally isotropic rocks from dominant gabbros to subordinated felsic rocks for this study two intrusions have been selected according to the geotectonic site of their emplacement the tah intrusion is located in the ophiolitic zone representing the remnants of the tethyan seafloor whilst the kharsareh intrusion is emplaced in the sanandaj sirjan metamorphic domain which corresponds to the border of the central iran plate starting with equivalent cumulates and gabbros the evolution of the two intrusions are clearly different the tah rock series comprises syenogabbros syenodiorites and syenites whereas silica oversaturated rocks appear in the karsareh series with the sequence of monzodiorites quartz monzonites and monzogranites the two intrusions show regular variations in their mineralogical and geochemical characters suggesting a direct genetic relationship within each rock series sr and nd isotopic compositions show smaller variations in the tah intrusion with sr and nd values respectively in the 6 7 to 12 4 and 3 3 to 5 4 ranges than in the karsareh intrusion with equivalent ranges of 16 to 99 and 0 4 to 5 2 the na k ba sr rb and ree contents of the gabbros although not truly representative of the primary magmas are typical of transitional basalts a two step combined wall rock contamination and crystal fractionation process would account for the evolution of the two series isotopic modelling suggests that during the first step which affects both intrusions the wall rocks would be basaltic rocks whereas during the second one only acting in the kharsareh intrusion the wall rock would be a hydrous continental crust the major differences between the two intrusions have been related to the geotectonic site of their emplacement

arabia eurasia collision and the forcing of mid cenozoic global cooling the end of the eocene greenhouse world was the most dramatic phase in the long term cooling trend of the cenozoic era here we show that the arabia eurasia collision and the closure of the tethys ocean gateway began in the late eocene at 35 ma up to 25 million years earlier than in many reconstructions we suggest that global cooling was forced by processes associated with the initial collision that reduced atmospheric co2 these are 1 waning volcanism across southwest asia 2 increased organic carbon storage in paratethyan basins e g black sea and south caspian 3 increased silicate weathering in the collision zone and 4 a shift towards modern patterns of ocean currents associated with increased vigour in circulation and organic productivity

late cenozoic reorganization of the arabia eurasia collision and the comparison of short term and long term deformation rates the arabia eurasia collision deforms an area of 3 000 000 km2 of continental crust making it one of the largest regions of convergent deformation on earth there are now estimates for the active slip rates total convergence and timing of collision related deformation of regions from western turkey to eastern iran this paper shows that extrapolating the present day slip rates of many active fault systems for 3 7 million years accounts for their total displacement this result means that the present kinematics of the arabia eurasia collision are unlikely be the same as at its start which was probably in the early miocene 16 23 ma or earlier in some but not all active fault systems short term 10 year and long term 5 million year average deformation rates are consistent there is little active thickening across the turkish iranian plateau and possibly the interior of the greater caucasus these are two areas where present shortening rates would need more than 7 million years to account for the total crustal thickening and where there are structural and or stratigraphic data for pre late miocene deformation we suggest that once thick crust up to 60 km built up in the turkish iranian plateau and the greater caucasus convergence took place more easily by crustal shortening in less elevated regions such as the zagros simple folded zone the south caspian region and foothills of the greater caucasus or in other ways such as westward transport of turkey between the north and east anatolian faults the time and duration of this changeover are not known for certain and are likely be diachronous although deformation started or intensified in many of the currently active fault systems at 5 2 ma

geochemical 40ar 39ar age and isotopic data for crustal rocks of the neyriz ophiolite iran trace element data including the rare earth elements in the crustal sequence of the neotethyan neyriz ophiolite in southwest iran indicate normal mid ocean ridge basalt n morb or island arc tholeiite chemistry for the tang e hana basalt the data suggest that the tang e hana rhyodacite basalt plagiogranite and gabbro derived from a low k tholeiitic parent magma trace element distributions in amphibolite clasts in the sole detachment of the ophiolite south of lake neyriz correlate well with distributions in basalt clasts in the melange and in the tang e hana basalt these trace elements suggest that the amphibolite originated from metamorphism and deformation of a tholeiitic basalt protolith new 40 ar 39 ar incremental heating plateau ages from two hornblende plagiogranite specimens in the crustal sequence in tang e hana are 92 07 1 69 and 93 19 2 48 ma isotopic data for five tang e hana basalts yield end values of 7 8 and 7 9 and 87 sr 86 sr values of 0 70368 to 0 70476 the isotopic compositions ophiolite tectonostratigraphy and correlation of the 40 ar 39 ar cooling plagiogranite and deformation amphibolite ages suggest emplacement of the neyriz ophiolite either into an accretionary prism through offscraping and subduction erosion and or formation in a supra subduction zone environment around 82 96 ma progressive accretion probably led to the de velopment of a fore arc basin and deposition of upper cretaceous eocene fore arc and arc derived sediments on the ophiolite resume des donnees sur les elements traces incluant les terres rares dans la sequence crustale de l ophiolite neo tethysienne de neyriz dans le sud ouest de l iran indiquent que le basalte de tang e hana est de type basalte oceanique de type n n morb ou une tholeiite d arc insulaire les donnees recueillies suggerent que la rhyodacite le basalte le plagiogranite et le gabbro de tang e hana proviennent d un magma tholeiitique parent a faible teneur potassique la repartition des elements traces dans les clastes amphiboliques dans l unique portion separee de l ophiolite au sud du lac neyriz est en bonne correlation avec celle trouvee dans les clastes basaltiques du melange ophiolitique et du basalte de tang e hana ces elements traces laissent penser que l amphibolite provient du metamorphisme et de la deformation d un protolithe de basalte tholeiitique de nouveaux ges 40 ar 39 ar par paliers de temperature pour deux specimens de plagiogranite a hornblende appartenant a la sequence crustale de tang e hana ont donne des valeurs de 92 07 1 69 ma et de 93 19 2 48 ma des donnees isotopiques de cinq basaltes de tang e hana ont donne des valeurs end de 7 8 et de 7 9 et des valeurs 87 sr 86 sr de 0 70368 a 0 70476 les compositions isotopiques la tectonostratigraphie ophiolitique et la correlation entre les ges 40 ar 39 ar de refroidissement plagiogranite et de deformation amphibolite laissent croire que l ophiolite de neyriz a ete mise en place dans le prisme d accretion sous l effet de l ecaillage et de l erosion par subduction et ou s est formee au sein d un environnement a zone de supra subduction il y environ 82 ma a 96 ma l accretion graduelle a probablement conduit au developpement d un bassin d avant arc et au depot de sediments provenant de l avant arc et de l arc sur l ophiolite au cours du cretace superieur et de l eocene

slip partitioning and inclined dextral transpression along the zagros thrust system iran abstract flexural duplex structures and shear zones are well developed in the heneshk area in southwestern iran the zagros thrust system in this area consists of eight sheets of nw striking ne dipping dextral strike slip duplexes that are linked with imbricate fans and oblique slip thrusts the zagros thrust system is a portion of the internal zone of the zagros orogenic belt this internal zone is characterized by penetrative plastic deformation and metamorphism based on the kinematic vorticity number w k 0 73 0 02 calculated from quartz porphyroclasts of the goshti shear zones along the zagros thrust system the estimated angle between the maximum instantaneous strain axis isa and the transpressional zone boundary is 33 the estimated angle of the plate convergence or the flow apophysis of the displacement field is 25 the presence of dominantly dextral shear sense indicators in the area is consistent with dextral inclined transpressional convergence the mean estimated finite deformation w m value indicates relative contributions of 47 pure shear and 53 simple shear for the deformation which involved both strike slip and oblique slip displacements in this inclined transpression about 40 strike slip partitioning was required to accommodate the finite strain and re orientation of instantaneous strain

effect of orogeny plate motion and land sea distribution on eurasian climate change over the past 30 million years the eurasian climates of today 10 million and 3o million years ago are simulated using an atmospheric general circulation model that incorporates realistic continental geography and epicontinental sea distributions the resulting climates compare well with various palaeoclimate records the retreat of the paratethys an epicontinental sea shifts the central asian climate from temperate to continental conditions and plays as important a role as uplift of the himalayan tibetan plateau in driving the asian monsoon changes

insights from the talysh of azerbaijan into the paleogene evolution of the south caspian region the age and mode of formation of the south caspian basin are disputed an 10 km thick predominantly middle eocene clastic and volcanic succession is exposed in the talysh mountains of azerbaijan at its western margin here high k alkali basalts pass laterally to the east and southeast into volcanogenic sandstone dominated turbidity current and debris flow deposits these southeasterly directed depositional systems accumulated in water depths generally greater than 200 m and fed directly into the western south caspian basin new ar ar ages cluster around 39 ma with an upper 1400 m thick volcanic interval being deposited in 2 2 0 2 m y we interpret that this rapid deposition and magmatism records a major back arc extensional transtensional event in the talysh north of the north dipping neotethyan subduction zone this event is recognized across much of southwest asia and may indicate a period of significant basin formation within the adjacent south caspian basin a transition into upper eocene lower oligocene strata dominated by fine grained turbidity current and hemipelagic sediments with slope instability features is interpreted to mark the end of rifting and volcanism in the talysh and the start of the arabia eurasia collision overlying oligocene coarse clastic rocks are interpreted as the erosional products of localized topography created by the further propagation of compressional deformation into the talysh region