present day deformation of northern pakistan from salt ranges to karakorum ranges episodic gps measurements are used to quantify the present day velocity field in the northwestern himalaya from the southern pamir to the himalayan foreland we report large postseismic displacements following the 2005 kashmir earthquake and several mm yr thrusting of the central segment of the salt ranges and potwar plateau over the foreland westward thrusting of nanga parbat above the kohistan plateau and 12 mm yr sse velocities of the karakorum ranges and of the deosai and kohistan plateaus relative to the indian plate numerical simulations allow to determine a first approximation of slip along active faults 1 substantial creep of 87 mm yr between 2006 and 2012 along the flat northeast of the balakot bagh thrust affected by the 2005 earthquake 2 5 mm yr slip of the central segment of the salt ranges and potwar plateau whereas their western boundaries are clearly inactive over the time span covered by our measurements 3 13 mm yr ductile slip along the main himalayan thrust modeled by a dislocation dipping 7 northward locked at a depth of 15 km and 4 20 mm yr slip along the shear zone forming the western boundary of nanga parbat between depths of 1 6 and 6 5 km residuals velocities suggest the existence of left lateral strike slip along the jhelum fault

magnitude scale and quantification of earthquakes despite various shortcomings the earthquake magnitude scale is one of the most fundamental earthquake source parameters to be used for catalogs although use of a uniform scale is desirable it is not always possible because of changes in instrumentation the data reduction method and the magnitude formula the station distribution etc as a result various magnitude scales have been developed and are currently in use recent developments in seismometry and earthquake source theories provide more quantitative source parameters than the magnitude in order to maintain continuity and uniformity of the data it is important to relate these magnitude scales and the new parameters in view of this importance relations between different magnitude scales are examined with an emphasis on the difference in the period of the waves used for the magnitude determination use of several magnitude scales determined at different periods provides a convenient method for characterizing earthquakes the moment magnitude can be used to quantify both shallow and deep earthquakes on the basis of wave energy radiated and provides a uniform scheme

surface rupture of the 2005 kashmir pakistan earthquake and its active tectonic implications to provide a detailed record of a relatively rare thrust surface rupture and examine its active tectonic implications we have conducted field mapping of the surface rupture associated with the 2005 m w 7 6 kashmir earthquake despite the difficulty arising from massive earthquake induced landslides along the surface rupture we found that typical pressure ridges and warps extend northwestward for a distance of 70 km with a northeast side up vertical separation of up to 7 m neither the main frontal thrust nor the main boundary thrust is responsible for the earthquake but three active faults or fault segments within the sub himalaya collectively called the balakot bagh fault compose the causative fault although the fault exhibits substantial geomorphic expression of repeated similar surface ruptures only a part of it had been mapped as active before the earthquake the location of the hypocenter suggests that the rupture was initiated at a deep portion of the northern central segment boundary and propagated bilaterally to eventually break all three segments our obtained surface rupture traces and the along strike slip distribution are both in good agreement with results of prompt analyses of satellite images indicating that space geodesy can greatly aid in time consuming field mapping of surface ruptures assuming that the extensive fill terrace in the meizoseismal area was abandoned during 10 30 ka we tentatively estimate the earthquake recurrence interval and shortening rate on the balakot bagh fault to be 1000 3300 yr and 1 4 4 1 mm yr respectively these estimates indicate that the balakot bagh fault is not a main player of himalayan contraction accommodation graphic 1 selected field photographs and arcgis files of the mapped surface rupture traces and measured vertical separations are available in the electronic supplement to this article 1 embed inline graphic 1 gif

surface waves generated by underwater explosions offshore scotland summary underwater explosions in the kirkcaldy bay region of the firth of forth scotland recorded by the british geological survey s lownet array crampin et al generate seismograms which are characterized by a long dispersed wavetrain on the assumption that these waves are caused by the shape of the dispersion curves phase and group velocities are analysed to determine the structural parameters of a model of the kirkcaldy bay region to which they are most sensitive the shear wave velocity and thickness of the sea bottom sediments are found to be most influential in determining the shape of these dispersion curves simple synthetic seismograms constructed for a solid model of the kirkcaldy bay region formed by excluding the water and sediment layers confirm that the extended wavetrain cannot be caused by the source the source effects increase the duration of the seismogram by only a few seconds compared to over 30 s for the effects of dispersion and are thus not significant it is demonstrated that for surface wave studies intended to probe the deeper solid basement using underwater explosions care must be exercised in selecting a shot location free from significant sediment thickness because these sediments effectively screen structure to between 10 and 100 times their own depth on the other hand the kirkcaldy bay surface wave seismograms also illustrate the detail with which sediment structure may be determined for acoustic and geological studies for example a 40 m thick sea bed sedimentary layer with shear wave velocity of about 0 2 km s 1 is resolved overlying a 1 4 km s 1 solid layer of 260 m thickness

comment on alam akhtar ahmad shabir sultan bhat m ahmad bashir 2015 tectonic evolution of kashmir basin in northwest himalayas geomorphology doi 10 1016 j geomorph 2015 03 025 abstract alam et al 2015 have challenged the classic piggyback tectonic model for the development of kashmir basin nw himalaya however all the evidence shown is completely contrary to the geologic tectonic structural seismologic geodetic and geomorphic data of previous works a perfectly planar major 165 km dextral strike slip fault has been mapped however with such planar geometry any strike slip fault cannot produce a pull apart basin because such basins are characteristic features of step overs and linkage fault geometries and the horsetail structures are impossible for a major planar strike slip fault geometry that is proposed by the authors the recent geodetic data of the kashmir basin strongly refutes the pure strike slip model therefore the structures geomorphology geology and kinematics associated with typical dextral strike slip fault geometry completely contradict to what has been proposed by alam et al 2015

cosmic ray labeling of erosion surfaces in situ nuclide production rates and erosion models a number of in situ cosmogenic radionuclides and stable nuclides have been measured in natural exposed rock surfaces with a view to study their in situ production and rock erosion rates 1 the in situ radionuclides can be used for a high resolution tomography of the erosional history of an exposed surface two stable nuclides 3he 21ne and five radionuclides 10be 26al 36cl 14c 39ar having half lives in the range of 300 1 5 106 yr half life are measurable in many rock types a prerequisite for the application of the in situ nuclides for the study of erosional histories of surfaces is a knowledge of their production rates under different irradiation conditions altitude latitude irradiation geometry and shielding relative nuclide production rates can be determined fairly accurately using the extensive available data on cosmic ray neutrons 2 absolute nuclide production rates cannot generally be predicted with any accuracy because of lack of data on excitation functions of nuclides unless some normalization is possible as was done in the case of several cosmic ray produced isotopes in the atmosphere 3 based on a recent natural calibration experiment in which erosion free surfaces exposed to cosmic radiation for 11 000 yrs were sampled the absolute production rates of 10be and 26al in quartz have been accurately estimated for mountain altitudes in sierra nevada 4 the absolute production rates of 10be and 26al in quartz can therefore be estimated fairly accurately for any given latitude and altitude some measurements of 14c in rocks of low erosion rate 5 similarly allow an estimate of its production rate attempts made to measure the in situ production rates of 3he in rocks have not yet led to a convergent production rate in view of the importance of knowing the production rates of isotopes of he ne and ar i present here theoretical estimates of their production rates based on available cross section data i discuss the information that can be extracted from the study of the in situ nuclides in rocks useful parameters characterizing the exposure history of a rock surface are 1 the effective surface exposure age and 2 the time averaged erosion rate the implications of these parameters for single and multiple nuclide studies are discussed in terms of the erosion models considered

uplift and convergence along the himalayan frontal thrust of india along the himalayan thrust front in northwestern india terrace deposits exposed 20 to 30 m above modern stream level are interpreted to have been uplifted by displacement on the underlying himalayan frontal thrust a radiocarbon age limits the age of the terrace to 1665 215 calendar bc 3663 215 radiocarbon years before present yielding a vertical uplift rate of 6 9 1 8 mm yr in combination with published studies constraining the dip of the himalayan frontal thrust fault to about 30 in the study area the observed uplift rate equates to horizontal shortening across the himalayan frontal thrust of 11 9 3 1 mm yr and the slip rate of the himalayan frontal thrust of 13 8 3 6 mm yr this is similar to previously reported rate estimates along the himalayan arc based on displacement of older plio miocene age rocks or the much shorter records of geodesy and historical seismicity the similarity is consistent with the idea that convergence across the himalayan front has occurred at a relatively steady rate through time the seismic expression of this deformation includes several great m 8 historical earthquakes which due to lack of surface rupture during those events have been attributed to their occurrence on blind thrusts yet the occurrence of a possible fault scarp in the field area indicates that past earthquakes have been sufficiently large to rupture to the surface and produce coseismic scarps these observations suggest a potential for earthquakes along the himalayan frontal thrust larger than those observed historically

stress field evolution in the northwest himalayan syntaxis northern pakistan 1 we have conducted a systematic inversion of striated fault planes throughout northern pakistan in order to better depict the temporal and spatial variations in stress patterns two domains are evidenced at a regional scale separated by the active raikhot fault the western boundary of the nanga parbat spur west of this fault a wrench type stress field with 1 axis oriented around n s predominates in the karakorum and in kohistan it predates pliocene quaternary exhumation of nanga parbat and corresponds to the miocene or earlier regional stress field related to indian asian convergence east of the raikhot fault compression parallel to the belt accounts for initiation of the nanga parbat anticlinorium after 5 ma it is followed by predominant post 2 ma extension both parallel to the belt and nne ssw oriented thus in the n w himalayan syntaxis multidirectional extension is juxtaposed on short timescales to shortening either parallel or perpendicular to the belt such juxtaposition could be characteristic of strain and stress partitioning during oblique convergence

geometry and kinematics of main frontal thrust related fault propagation folding in the mohand range northwest himalaya abstract the main frontal thrust mft shapes the 2500 km long frontal himalayan arc between two syntaxes surprisingly the structural geometry and kinematics of the mft sheet remains poorly constrained along portions of this arc even though it is a major seismogenic plate boundary hazard that affects 53 million people living in the himalaya and roughly 600 million living in the combined himalayan drainage basin apollo 2017 here we integrate methods to constrain and quantify mft deformation and its associated topographic growth in the mohand range at the northwestern himalayan front we use a new structural data and trishear modeling to detail the mft related structural geometry across a portion of the range and confirm it to be a fault propagation fold with an exposed monocline in the hanging wall as previously hypothesized srivastava et al 2016 and b microstructural finite strain and grain size analysis from 11 transport parallel thin section samples of middle siwalik sandstones to propose that the fold formed by near surface 1 5 km frictional sliding and block supported cataclastic flow new luminescence dating of fault gouge and uplifted sand bodies indicate that mft activity is older 105 ka in the central compared to the western 15 ka mohand range implying that recent mft motion has been variable and segmented we next present boundary element method based dislocation modeling results along 3 transects to confirm that the along strike topographic growth is variable but consistent with the existing data and our interpretations balanced cross sections indicate that a maximum of 23 26 km2 area was eroded from the mohand range since folding began modern era estimates of minimum erosion from our dislocation modeling compared to existing topographic profiles suggest that 1 km2 erosion occurred in the range our integrated approach helps us to better constrain resolve reported inconsistencies and advance our understanding of mft related deformation topographic growth and erosion within the dehradun recess and across its outboard range front himalayan arc segmentation into salients and recesses likely impacts along strike earthquake rupture propagation thus it is important to understand how each segment behaves evolves and perhaps interrelates as part of a larger perspective towards evaluating active collisional wedge fronts and their potential seismic hazards

recurrence of large paleo earthquakes in kashmir himalaya seismic gap riasi area india abstract in kashmir himalaya the medlicott wadia thrust is a main active fault responsible for the crustal accretionary prism building during the late quaternary because of the long seismic silence during the last five centuries it is a key structure to be studied in order to estimate the regional seismic hazard in the riasi area the analysis of two paleoseismological trenches allowed us identifying and measuring several seismic ruptures over the last 3500 years we determined that the oldest rupture occurred around 1600 1000 bc while the youngest occurred after 1470 ad the latest event is compatible with the great 1555 ad mw 7 5 kashmir earthquake whose evidence at the surface had not yet been recognized our results show that despite the long lasting seismic gap the medlicott wadia thrust is a main seismogenic structure in the region able to produce large earthquakes their recurrence interval ranges between 500 and 700 years implying that a main seismic event could occur in the next decades these seismic ruptures are localized over gently dipping fault branches associated with decameter scale scarps the morphologies observed are due to a significant non localized component of the deformation in quaternary sediments

field documentation and genesis of back structures in ductile and brittle regimes from the foreland part of a collisional orogen examples from the darjeeling sikkim lesser himalaya india in the foreland side of an orogen thrust related structures develop that verge towards the foreland fore thrusts although much less abundant structures with opposite vergence i e towards hinterland named back structures also exist we report back structures exposure scale back thrusts and associated folds from the darjeeling sikkim lesser himalaya india these structures occur mainly in three back structure zones bsz a b and c back structures probably originated in the ductile regime and continued in the brittle domain tectonic setting of the study area such as critical taper duplexing etc indicates a good potential for the presence of back structures in this region along with the previous work on back structures in collisional orogens himalaya in particular these structures seem to be ubiquitous the correlation of field observations with tectonics indicate that mechanisms e g critical taper sub surface barriers and passive roof duplex played roles in forming back structures in this part of the sikkim lesser himalaya

structure and shortening of the kangra and dehra dun reentrants sub himalaya india surface geology oil well seismic reflection and magnetostratigraphic data are integrated to evaluate the structural style and the shortening rate at the himalayan front sub himalaya of northwest india the sub himalaya between the main boundary thrust and the himalayan frontal fault is the primary surface expression of shortening between the himalaya and the indian plate at certain locations the himalayan frontal fault is a blind thrust beneath anticlines of siwalik tertiary molasse parallel to the himalayan orogen the main boundary thrust is sinuous so the width of the sub himalaya ranges from 30 to 80 km where the sub himalaya is narrow nahan salient tertiary rocks are exposed in imbricate thrust sheets where the sub himalaya is broad kangra and dehra dun reentrants alluvium fills wide synclinal valleys duns seismic reflection data reveal that surface anticlines form in association with south vergent thrusts that root in a decollement at the base of the tertiary section reflection profiles and well data also indicate that the basement lithology changes northward from precambrian crystalline rocks beneath the indo gangetic plains to precambrian and cambrian metasedimentary rocks beneath the sub himalaya the sub himalayan decollement dips 2 5 northward beneath the kangra reentrant but it is steeper 6 beneath the dehra dun reentrant the kangra and dehra dun reentrants display fault propagation folds having steep limbs in the north and fault propagation and fault bend folds that have gently north dipping limbs in the south a balanced cross section of the kangra reentrant shows that a minimum of 23 km shortening has occurred since 1 9 1 5 ma yielding a shortening rate of 14 2 mm yr shortening has occurred at a rate of 6 16 mm yr across the dehra dun reentrant these data are similar to other published shortening rates and indicate that approximately 25 of the total india eurasia convergence at this longitude is accommodated within the sub himalaya given continued convergence and the presence of overpressured wells in the kangra reentrant the region is likely at risk from moderate and or great earthquakes in the future

distribution of the late quaternary deformation in northwestern himalaya abstract three main cenozoic thrusts at the front of northwestern himalaya have accommodated most of the india eurasia convergence across the belt over the last million years and produced the present relief their recent tectonic activity is poorly known because of the long period of inaccessibility of the jammu and kashmir state and because the latest and only large earthquake recorded in the region occurred in 1555 ad we show where the deformation is localized during the late quaternary and determine shortening rates across the structures by analyzing the geometry and chronology of geomorphic markers the main boundary thrust in this region ceased moving at least 30 ka ago on the contrary the more external medlicott wadia thrust and main frontal thrust both merging at depth on the sub flat detachment of the main himalayan thrust exhibit hectometric scale deformations accumulated during the last thousands of years the total shortening rate absorbed by these faults over the last 14 24 ka is between 13 2 and 27 2 mm yr 11 2 3 8 and 9 0 3 2 mm yr respectively part of this deformation may be associated to the geometry of the chenab reentrant which could generate an extra oblique component however the lower bound of our shortening rates is consistent with previously determined geodetic rates active deformation on these structures follows an in sequence out of sequence pattern with breaking of both ramps being possible for earthquakes triggered on the main detachment

india eurasia collision chronology has implications for crustal shortening and driving mechanism of plates the motion of the indian plate is determined in an absolute frame of reference and compared with the position of the southern margin of eurasia deduced from palaeomagnetic data in tibet the 2 600 900 km of continental crust shortening observed is shown to have occurred in three different episodes subduction of continental crust intracontinental thrusting and internal deformation and lateral extrusion the detailed chronology of the collision and plate reorganizations in the indian and pacific oceans supports the hypothesis that slab pull is a dominant driving mechanism of plate tectonics

seismotectonics of the himalayan collision zone geometry of the underthrusting indian plate beneath the himalaya fault plane solutions and well determined focal depths of medium sized earthquakes topography and landsat imagery in conjunction with seismicity maps cross sections and available geological information are used to investigate the present tectonics of the himalayan continental collision zone most of the accurately located epicenters of events along the himalayan arc 78 e 95 e that occurred between 1961 and 1981 are concentrated in a narrow zone about 50 km wide lying between the northerly dipping main boundary mbt and main central mct thrusts most of these events are located just south of the mct though the epicenters of the events are in general well located their depths as determined by teleseismic travel time data are very unreliable events with accurately determined depths obtained from identification of surface reflected phases define a simple planar zone from about 10 km and 20 km depth with an apparent dip of about 15 this result is all the more remarkable considering that the events used were located along about an 1800 km length of the himalyan arc except for one all available focal mechanisms of events within this zone indicate shallow 30 north dipping thrusts this shallow north dipping zone apparently defines a part of the detachment that separates the underthrusting indian plate from the lesser himalayan crustal block the spatial extent and the geometry of this interplate thrust zone strongly indicate that the mbt and nearby subsidiary surface and blind thrusts rather than the mct are currently the most active structures of the himalayan arc we suggest that the great himalayan earthquakes m 8 occur along the same detachment surface as defined by the thrust type medium sized events events located to the south of the mbt and beneath the ganges foredeep show normal faulting with t axes perpendicular to the himalayan trend the above results suggest that the indian continental plate is underthrusting the himalayan crustal blocks in a relatively coherent and simple geometry and that this geometry is not much different from that observed along oceanic subduction zones the november 19 1980 earthquake that occurred near the mct near 88 5 e shows a predominantly strike slip focal mechanism one of the nodal planes of this mechanism is transverse to the himalayan structural grain and moreover this plane has a trend similar to that of the recently mapped yadong gulu rift in the tethyan himalaya and in southern tibet just northeast of the earthquake we interpret this predominantly left lateral strike slip mechanism to indicate a possible genetic relationship between transverse structural features in the underthrusting indian plate the kishangang basement fault and the upper himalayan blocks and tibet

slow tilt reversal of the lesser himalaya between 1862 and 1992 at 78 e and bounds to the southeast rupture of the 1905 kangra earthquake summary measurements between 1862 and 1992 of a 77 km long spirit levelling line that crosses the main frontal thrust of the himalaya near dehra dun 78 e reveal a slow reversal of tilt in the early part of the last century unperturbed by the destructive 1905 april 4 kangra earthquake 200 km to the northwest the lesser himalaya are inferred to be tilting currently to the northeast at 0 08 rad yr 1 with similar rate but opposite sign to their tilt in 1862 the absence of co seismic deformation near dehra dun in 1905 indicates that the kangra rupture terminated short of dehra dun consistent with a revised ms 7 8 estimate for the size of the kangra earthquake but inconsistent with previous analyses of the levelling data that interpret a large slope dependent systematic error as co seismic slip the reversal in tilt corresponds to a linear northeast down tilt acceleration of 0 0015 0 0004 rad yr 2

fashion and phases of late pleistocene aggradation and incision in the alaknanda river valley western himalaya india abstract we study the aggradation and incision of the alaknanda river valley during the late pleistocene and holocene the morphostratigraphy in the river valley at deoprayag shows the active riverbed a cut terrace and a fill terrace the sedimentary fabric of the fill terrace comprises four lithofacies representing 1 riverbed accretion 2 locally derived debris fan 3 the deposits of waning floods and 4 palaeoflood records the sedimentation style coupled with geochemical analysis and optically stimulated luminescence osl dating indicate that this terrace formed in a drier climate and the river valley aggraded in two phases during 21 18 ka and 13 9 ka during these periods sediment supply was relatively higher incision began after 10 ka in response to a strengthened monsoon and aided by increase of the tectonic gradient the cut terrace formed at 5 ka during a phase of stable climate and tectonic quiescence the palaeoflood records suggest wetter climate 200 300 yr ago when the floods originated in the upper catchment of the higher himalaya and in the relatively drier climate 1 2 ka when locally derived sediments from the lesser himalaya dominated flood deposits maximum and minimum limits of bedrock incision rate at deoprayag are 2 3 mm a and 1 4 mm a

structure of the earth oceanic crust and uppermost mantle the past four years have witnessed the introduction of a variety of new instruments and methods for the study of the seismic structure of the oceanic crust and lithosphere the application of these and existing tools has led to the discovery of a number of new phenomena and to a fuller understanding of the genesis and evolution of the oceanic ithosphere borehole seismic instrumentation has become more widely employed ocean bottom seismographs while generally decreasing in number have become significantly more reliable and useful and multichannel seismic systems have been employed in innovative experiments ranging from studies of fracture zones to the regular detection of magma chambers beneath rise axes the techniques available for the analysis of seismic data have become more sophisticated waveforms collected in seismic experiments can now be used directly in constructing and evaluating seismic velocity models and travel time data are regularly inverted directly for structure trial and error modeling has become increasingly unimportant marine seismologists are becoming increasingly involved in understanding the coupling between the ocean and the underlying oceanic lithosphere this has led to a more complete understanding of seafloor noise processes and the partitioning of energy between acoustic and elastic waves

coseismic displacement field and slip distribution of the 2005 kashmir earthquake from sar amplitude image correlation and differential interferometry the coseismic surface displacement field and slip distribution at depth due to the kashmir earthquake mw 7 6 2005 have been analysed by different authors using subpixel correlation of synthetic aperture radar sar images and optical images teleseismic analysis gps measurements as well as in situ field measurements in this paper first we use 23 sets of measurement from subpixel correlation of sar images and differential interferometry to retrieve the 3 d coseismic surface displacement field the obtained horizontal and vertical components along the fault trace are then compared respectively to equivalent measurements obtained from subpixel correlation of two optical aster images and in situ field measurements second the coseismic fault geometry parameters and slip distribution at depth are estimated in addition to the one segment slip model as reported in previous work a two segments slip model that better fits the surface fault break is proposed the improvement of the two segments slip model in interpreting the measured displacement field is highlighted through comparison of residuals of both slip models taking advantage of differential interferometry measurements that provide precise and continuous information in the far field of the fault firstly a wedge thrust according to bendick et al to the northwest of the main rupture built on our two segments model is tested according to the obtained results the residual of the two segments main rupture plus wedge thrust model is slightly smaller than the residual of the two segments model to the northwest of the balakot bagh fault secondly we test the sensitivity of our slip model to the presence of slip along a decollement as evidenced by jouanne et al through post seismic analysis the results indicate that the estimations of the coseismic displacement field and slip distribution in this paper are not significantly biased by such post seismic displacement and that most coseismic displacement is located on a 40 ne dipping fault as previously reported

structural interpretation of the great earthquakes of the last millennium in the central himalaya abstract a major question about the himalaya remains open does a great earthquake like the mw 8 1 1934 earthquake release all the strain stored by the tibet india convergence during the preceding interseismic period and only that strain or can it also release a background store of energy that remained unreleased through one or more earlier earthquakes and so potentially engender giant events or a relatively random sequence of events to consider this question the history of the great earthquakes of the last millennium is investigated here by combining data provided by the historical archives of kathmandu trenches through surface ruptures isoseismal damage mapping seismites and the instrumental record in the kathmandu basin the location of the epicenter of the 1934 earthquake was determined from the arrival of high energy p waves that caused sedimentary dikes and ground fractures perpendicular to the epicenter azimuth the epicenter of the mw 7 6 1833 earthquake can therefore be determined analogously from dike orientation and its location to the ne of kathmandu indicates an overlap with the mw 8 1 1934 rupture the 1934 earthquake released strain not released by the 1833 earthquake comparison of the historical records of earthquakes in kathmandu with 14c ages from paleo seismic trenches along the himalayan front suggests that 1 the 1344 kathmandu event ruptured the surface as far away as kumaon and was therefore a giant mw 8 6 earthquake and 2 the 1255 event that destroyed kathmandu is attested by surface ruptures in central and western nepal and by seismites in soft sediment as far away as kumaon geometric and rheologic controls for the different types of ruptures during the medium mw 7 great mw 8 and giant mw 8 4 earthquakes are illustrated in structural cross sections it is found that the epicenters of great himalayan earthquakes are located on the basal thrust farther north or close to the locked zone which is defined from geodetic measurements of regional deformation during the interseismic period this suggests that great earthquakes initiate in a wide transition zone between exclusively brittle and exclusively creeping regimes the extent of which depends on the dip of the main himalayan thrust the succession of the great earthquakes during the last millennium has released all the 20 m millennial himalayan convergence even in the central seismic gap which has been locked since 1505 the millennial seismic release rate is close to the convergence rate nonetheless no evidence of a succession of characteristic earthquakes has been found the 1100 1833 and 1934 earthquakes in the eastern himalaya are characterized neither by constant displacement nor by constant recurrence furthermore some great earthquakes do not release all the strain elastically stored by the himalayan and tibetan upper crust after the 1255 event there was still the potential for a slip of several meters for the mw 8 1 1505 event this suggests a rather random release of seismic energy great earthquakes could occur anytime and in any part of the central himalaya furthermore a future giant earthquake of mw 8 6 cannot be excluded

surface deformation in the region of the 1905 kangra mw 7 8 earthquake in the period 1846 2001 1 one century after the mw 7 8 kangra earthquake of 4 april 1905 we report weak constraints on its rupture parameters based on the remeasurement of historic triangulation points in the epicentral region the western corner of the 1905 rupture is constrained to within 20 km and its sw edge strikes n135 15w the down dip width of the rupture is inferred from the location of the interseismic locking line to have been less than 55 km scaling laws and revised msk intensities suggest an along arc rupture length of 100 km with uniform slip of 4 m because the earthquake ruptured 60 of the width of the plate boundary and released a fraction of the inferred slip deficit complacency about its re rupture in the distant future is unwarranted the kangra rupture could fail again today in a mw 7 5 earthquake 1 4 m of slip or as part of a much larger earthquake mw 8 6

redefining medlicott wadia s main boundary fault from jhelum to yamuna an active fault strand of the main boundary thrust in northwest himalaya abstract the mbt demarcates a tectonic boundary between the tertiary sub himalaya and the pre tertiary lesser himalaya south of the mbt another tectonically important fault extends from muzaffarabad and riasi in jammu kashmir to bilaspur and nahan in himachal medlicott and wadia had designated this fault the main boundary fault mbf in simla hills and jammu region respectively in between these two areas later workers gave local area names to the mbf as the riasi thrust in jammu palampur thrust in kangra bilaspur thrust in simla hills and nahan thrust in sirmur we have reviewed and established the tectonostratigraphic framework and physical continuity of the lower tertiary belt and the mbf the lower tertiary belt lying south of the mbt has characteristic tectonostratigraphic setting with discontinuous bodies of stromatolite bearing proterozoic limestone overlain with depositional contact by the paleocene lower part middle eocene marine subathu patala formation which in turn overlain by the upper oligocene lower miocene non marine dharamsala murree formation to avoid confusion with the mbt we designate collectively the mbf and related faults as the medlicott wadia thrust mwt the mwt extends east of hazara kashmir syntaxis to river yamuna covering a distance of 700 km further east of yamuna the lower tertiary belt pinches out and the mwt merges with the sensuo stricto mbt the proterozoic limestone represents the basement over which the lower tertiary sediments were deposited the limestone basement with its cover was detached by the mwt exhuming to the surface and thrusting over largely the siwalik group the reactivated balakot bagh fault causative fault for the 2005 kashmir earthquake extends southeast with right step to the riasi thrust the riasi thrust shows evidence of reactivation and active tectonic activity in jammu region it extends further east to the palampur thrust in kangra reentrant which lies within the 1905 kangra earthquake rupture zone the bilaspur thrust continuation of the palampur thrust shows active faulting south of simla hills between sataun and yamuna river these observations indicate that the mwt represents a southern strand of the sensuo stricto mbt and shows active faulting in some segments

some elements of continental subduction along the himalayan front abstract detachment tectonics in which the subducting basement is not internally affected by thrusting and a steady state system in which the pattern of deformation and topography are invariant uplift is balanced by erosion and the material can experience subsequent phases of deformation by migrating through the system are proposed to be the fundamental mechanisms of convergence at the himalayan arc both surface and subsurface data are more consistent with these concepts than with more familiar concepts widely used in current models intracrustal thrusting and evolutionary tectonics where superimposed phases of deformation are interpreted as distinct phases the belt of intermediate magnitude thrust earthquakes the topographic front at the high himalaya and the main central thrust mct are associated with the same fundamental element the basement thrust front btf which traces a small circle in the central portion of the himalayan arc fault plane solutions indicate thrusting in the radial direction of this arc this radial convergence at the btf implies that tibet is extending laterally at a rate similar to the rate of convergence across the btf this extension cannot be unidirectional and must be parallel to the btf if the circular shape of the btf is invariant

postseismic deformation in pakistan after the 8 october 2005 earthquake evidence of afterslip along a flat north of the balakot bagh thrust 1 the 8 october 2005 kashmir earthquake ruptured an out of sequence himalayan thrust known as the balakot bagh thrust the earthquake s hypocenter was located at a depth of 15 km on the ramp close to a possible ramp flat transition in the weeks following the earthquake a gps network was installed to measure postseismic displacement the initial measurements in november 2005 were followed by other campaigns in january and august 2006 in march and december 2007 and in august 2008 and 2009 two hypotheses were tested post seismic displacements controlled by viscous relaxation of the lower crust or by afterslip along a flat north of the ramp affected by the main shock a single newtonian viscosity for the different periods cannot be determined by numerical simulations of viscous relaxation which may indicate that the viscosity of the lower crust is non newtonian or that viscous relaxation does not control postseismic displacements numerical simulations using dislocations in a uniform elastic half space indicate afterslip north of the ramp of the earthquake along a flat connected to the ramp slip along the northwestern portion of the flat accrued to about 285 mm between november 2005 and august 2006 while slip along the southeastern portion accrued to 130 mm over the same time period residual misfit of the observed and predicted displacements clearly indicated that afterslip is a better explanation for the observations than the hypothesis of viscous relaxation the time evolution of the afterslip was found to be consistent with that predicted from rate strengthening frictional sliding

late quaternary out of sequence deformation in the innermost kangra reentrant nw himalaya of india seismic potential appraisal from 10 be dated fluvial terraces abstract the kangra reentrant is a convex to the northeast u shaped structure in the nw himalaya where the sub himalayan fold and thrust belt is 90 km wide this region has not been struck by large earthquakes since the 1905 mw 7 8 kangra earthquake out of sequence deformation has been reported at the millennial timescale along intracrustal thrusts within this reentrant such as the jawalamukhi thrust up to now the occurrence of out of sequence deformation along inner thrusts within the kangra reentrant during the late quaternary has not yet been addressed in this study the results of a neotectonic survey undertaken in this reentrant are presented the studied zone is located between the beas and the neogad rivers and encompasses from the jawalamukhi thrust to the main boundary thrust two terraces that are deformed by branches of the medlicott wadia thrust locally named the palampur thrust are identified this is evidenced in the field by metric scale fault scarps by using 10be dating the ages of these terraces were constrained to ca 7 5 and ca 6 2 ka this is clear evidence of the late quaternary out of sequence deformation in the innermost part of this reentrant implying that strain is distributed along all the arc orthogonal extent of the local fold and thrust belt over this timespan a cumulative slip rate of ca 1 mm yr along the studied thrusts which represents 10 of the bulk strain accommodated by the whole reentrant for this timespan is calculated in spite of the marginal appearance of this figure this deformation rate is attributed to 7

geological and geomorphic evidences of neotectonic activity along the himalayan frontal thrust nahan salient nw himalaya india abstract in this paper we report geomorphic signatures of neotectonic activity identified from the area around nahan salient along himalayan frontal thrust hft using remote sensing and field investigations we document two newly discovered exposures of hft fault zone and active fault traces along the mountain front at khetpurali nahan salient nw himalaya india we demonstrate that hft fault zone at khetpurali is not blind instead it is exposed at the surface along with highly deformed folded strata in the hanging wall and its geometry is quite variable with the possibility of along strike segmentation the geometry of fold and various deformational features preserved in the hanging wall indicate a process of fault propagation fold this is in contrast to the previous observation of fault bent folding within the nahan salient two three levels of river terraces are preserved and truncated in the hanging wall along with the active fault scarps which are linked to uplift along hft fault zone the khetpurali anticline ka is a fault propagating fold formed due to displacement and shortening along hft which dips 30 towards north and strike wnw ese the uplift u along the ka is calculated to be 73 m and accommodated 7 3 shortening of the original length before the fault tip truncated the fold various deformational structures have been identified within the hanging wall around tip damage zone of 80 m perpendicular to hft fault zone and in the core of ka northwest of khetpurali a south facing hogback structure 100 m high is formed due to erosion of forelimb of the anticline at khetpurali tectonic control due to folding of strata and uplift of river terraces is evident as the dudhgarh river forms v shaped profile near the thrust compared to the wide floodplain before and after crossing the hft fault zone along strike segmentation of hft and associated anticlines is observed as the surface trace of hft is offset at khetpurali trilokpur and sabilpur due to the strike slip faults the study reveals that hft has been truncated by tear faults and has different subsurface geometries in study area which may have implication on seismic hazard in the nahan salient where three thrusts himalayan frrontal thrust hft nahan thrust nt and main boundary fault mbf are located at relatively shorter distance of 6 km as compared to the surrounding recesses

a complex thrust sequence in western himalaya the active medlicott wadia thrust the recent activity of the medlicott wadia thrust mwt is investigated by geomorphic and tectonic studies in the riasi zone south of the pir panjal range india jammu kasmir state of western himalaya in the riasi area the mwt forms a splay of five faults that dip northward the recent activity of the splay is quantified using a set of deformed quaternary alluvial units the central branch of the thrust splay moved precambrian limestones above quaternary sediments and is sealed by 36 3 ka youngest osl age deposits the other branches offset the top of a 15 1 ka youngest osl age alluvial fan by 180 to 120 m the two southernmost branches form 17 34 m high non cylindrical scarps and the two northernmost branches also offset the fan by 8 m and 54 m respectively a balanced cross section parallel to the n210 e thrust motion suggests that the sequence of activity is complex an in sequence propagation is found for the three southern tea scorpion and rain faults and an out of sequence reactivation for the northern pillar fault furthermore several thrusts simultaneously activated for intervals of a few thousand years whereas others are episodically inactive nearly 10 mm yr of india eurasia convergence is regularly absorbed by the mwt a value greater than the one estimated for the western segment of the mwt affected by the 2005 kashmir earthquake where the thrust tectonics interacts with the complex kinematics of the syntax this work indicates that the mwt is very active and might be related to thick skinned tectonics in the western himalaya

scaling factors for the rates of production of cosmogenic nuclides for geometric shielding and attenuation at depth on sloped surfaces abstract the decrease in rates of production of cosmogenic nuclides occurs because of shielding of cosmic rays by mountains sloped surfaces and local rock formations that block them when a large part of the sky is blocked this correction is large and requires detailed model calculations this paper considers three geometries a rectangular obstruction a triangular obstruction and a sloped surface other geometries can be considered as a combination of these the results are presented in terms of formulas and graphs so that the reader can easily apply them to common field situations any use of cosmogenic nuclides in the study of geomorphic processes or forms must consider factors that introduce variations in the production of nuclides

the late cenozoic chronologic and stratigraphic development of the kashmir intermontane basin northwestern himalaya abstract the intermontane basin of kashmir developed within the thrust faulted southern margin of the himalayan range detailed lithostratigraphies magnetic polarity stratigraphies and fission track dates on enclosed volcanic ashes were determined at four separate localities in order to develop a chronology of the late cenozoic evolution of the kashmir basin the results indicate that sedimentation had commenced by about 4 m y ago since then over 1300 m of sediments have aggraded at inferred average rates varying from 16 to 64 cm per 1000 yr lacustrine and deltaic sediments dominate the kashmiri sequences and appear to respond sensitively to tectonic events along the basin margins conglomerates shed from the faulted basin margins at about 1 7 2 1 2 7 and 3 0 3 5 m y ago punctuate the predominantly low energy fluviolacustrine depositional record paleocurrent analyses indicate a switch from northeasterly derived conglomeratic facies to southwesterly derived ones about 1 7 m y ago this transition reflects enhanced activity along the main boundary thrust complex to the southwest and an apparent diminution of faulting along the northeastern margin of the basin in the pir panjal range 1400 3000 m of uplift at inferred rates of up to 10 mm yr 1 have terminated widespread sedimentation within the kashmir basin since the middle pleistocene

kashmir basin fault and its tectonic significance in nw himalaya jammu and kashmir india the kashmir basin fault is located in the jammu and kashmir region of kashmir basin in nw himalaya india it is a classic example of an out of sequence thrust faulting and is tectonically active as observed from multiple geological evidences its geomorphology structure and lateral extent indicate significant accommodation of stress since long which is further supported by the absence of a large earthquake in this region it seems this fault is actively accommodating some portion of the total india eurasia convergence apart from two well recognised active structures the medlicott wadia thrust and the main frontal thrust which are referred in vassallo et al earth planet sci lett 411 241 252 2015 this requires its quantification and inclusion into slip distribution scheme of nw himalaya therefore it should be explored extensively because this internal out of sequence thrust could serve major seismic hazard in kb repeating a situation similar to muzaffarabad earthquake of northern pakistan in 2005

seismic slip deficit in the kashmir himalaya from gps observations 1 gps measurements in kashmir himalaya reveal range normal convergence of 11 1 mm yr with dextral shear of 5 1 mm yr the transition from a fully locked 170 km wide decollement to the unrestrained descending indian plate occurs at 25 km depth over an 23 km wide transition zone the convergence rate is consistent with the lower bounds of geological estimates for the main frontal thrust riasi and balapora fault systems on which no surface slip has been reported in the past millennium of the 14 damaging kashmir earthquakes since 1123 none may have exceeded mw 7 6 therefore either a seismic moment deficit equivalent to a mw 8 7 earthquake exists or the historical earthquake magnitudes have been underestimated alternatively these earthquakes have occurred on reverse faults in the kashmir valley and the decollement has been recently inactive although this can reconcile the inferred and theoretical moment release it is quantitatively inconsistent with observed fault slip in kashmir

in situ produced 10be measurements at great depths implications for production rates by fast muons in situ cosmogenic 10be values have been used to investigate a brazilian quartz vein from the surface to a depth of 15 m at depths greater than 1000 g cm2 deep enough for neutron induced reactions to be insignificant there is only a slight decrease in 10be concentration with increasing depth our results are consistent with deep production of 10be by a mechanism presumably induced by fast muons with an attenuation length of 5300 950 g cm2 and a contribution of 0 65 0 25 to the total surface production results are compared with values from the literature and implications of this re evaluation are discussed

reply to comments by ahmad et al on shah a a 2013 earthquake geology of kashmir basin and its implications for future large earthquakes international journal of earth sciences doi 10 1007 s00531 013 0874 8 and on shah a a 2015 kashmir basin fault and its tectonic significance in nw himalaya jammu and kashmir india international journal of earth sciences doi 10 1007 s00531 015 1183 1 shah int j earth sci 102 1957 1966 2013 mapped major unknown faults and fault segments in kashmir basin using geomorphological techniques the major trace of out of sequence thrust fault was named as kashmir basin fault kbf because it runs through the middle of kashmir basin and the active movement on it has backtilted and uplifted most of the basin ahmad et al int j earth sci 2015 have disputed the existence of kbf and maintained that faults identified by shah int j earth sci 102 1957 1966 2013 were already mapped as inferred faults by earlier workers the early works however show a major normal fault or a minor out of sequence reverse fault and none have shown a major thrust fault

sedimentation close to the active medlicott wadia thrust western himalaya how to estimate climatic base level changes and tectonics the medlicott wadia thrust mwt is one of the major active out of sequence thrusts in the himalaya studies on quaternary terraces in its vicinity have been performed using sedimentological geomorphic and geochronological methods we focus on the riasi zone south of the pir panjal range in the jammu and kashmir region of india the sedimentary units of quaternary landforms have been mapped as a function of their location with respect to the thrust faults their relative chronology and their lithology three aggrading sedimentary units five thin units above strath surfaces at the footwall of the fault system and seven thin units above strath surfaces at its hangingwall are identified the terraces have been dated by combining optically stimulated luminescence osl on fine grained deposits and cosmogenic nuclide dating 10be on sandstone pebbles sampled along depth profiles throughout the alluvial units three major allostratigraphic units were defined with upper surface ages estimated at 4 15 and 36 3 ka the two older allostratigraphic units are encased terraces at the hangingwall but superposed sedimentary units at the footwall they are related to phases of elevation of the river level respectively 30 and 60 m at 36 38 and 14 15 ka and to a phase of extensive lateral incision before 4 ka these units present vertical offsets induced by the mwt of 50 190 and 375 m respectively by taking the aggradation incision rates at the footwall of the mwt into account we found that the uplift of the hangingwall remains uniform since 36 ka with a value of 10 mm yr therefore the aggradation incision events observed in the riasi area cannot be ascribed to variations in the tectonic rates and are most likely driven by climatic fluctuations the high uplift rate is possibly local and related to the chenab recess which affects the himalayan frontal structure our results indicate that the mwt is an active growth fault and one of the main emergences of the active indian asian plate boundary in western himalaya

explicit treatment of inheritance in dating depositional surfaces using in situ 10be and 26al we describe a new strategy for dating depositional landscape surfaces using in situ produced cosmogenic radionuclides crns that removes the complication of nuclide inheritance by clasts prior to depositon two amalgamated samples each consisting of 30 clasts one from the surface and one from a fixed depth in the subsurface constrain this crn inheritance and date the surface the inheritance may be used to estimate minimum exhumation rates and maximum transport times within the geomorphic system we test the technique using sup 10 be and sup 26 al to date the third fr3 of five terraces along the fremont river utah and the third wr3 of 15 along the wind river wyoming whereas effective ages based solely upon the surface samples yield 118 138 ka fr3 and 93 ka wr3 the subsurface samples reveal that inheritance accounts for 22 wr3 to 43 fr3 of the total crn concentration taking this into account yeilds terrace ages of nearly 61 81 ka for fr3 and nearly 67 76 ka for wr3 we explore the dependence of age estimates on the accumulation history of the terrace silt caps 22 refs 3 figs 1 tab

the 2005 mw 7 6 kashmir earthquake sub pixel correlation of aster images and seismic waveforms analysis we analyze the m w 7 6 kashmir earthquake of october 8 2005 using sub pixel correlation of aster images to measure ground deformation and modeling seismic waveforms the surface rupture is continuous over a distance of 75 km and cuts across the hazara syntaxis reactivating the tanda and the muzaffarabad faults north of muzaffarabad the surface rupture coincides approximately with the mbt on the southwestern flank of the syntaxis although the two faults have opposite dip angles the rupture terminates abruptly at the hairpin turn of the mbt showing a strong structural control the fault offset is 4 m on average and peaks to 7 m northwest of muzaffarabad the rupture lasted about 25 s and propagated updip and bi laterally 2 km s with a rise time of 2 5 s the shallowness and compactness of the rupture both in time and space provide an explanation for the intensity of destructions this kind of analysis could be achieved as soon as a post earthquake image is available and would provide key information for early assessment of damages the study sheds some light on seismic hazard in the himalaya and raises concern regarding the possibility of a repetition of the 1555 event which presumably ruptured the himalayan front south of the kashmir basin and may have reached a magnitude m w 8

surface ruptures of large himalayan earthquakes in western nepal evidence along a reactivated strand of the main boundary thrust the chronology of the seismic ruptures along the active faults of western nepal remains almost unconstrained despite their high seismogenic potential we present here a slip history of one of these structures a 120 km long reactivated segment of the main boundary thrust named the surkhet gorahi fault this slip history is based on geomorphologic and neotectonic mapping of active faults deduced from the analysis of a high resolution total station digital elevation model and 15 detrital charcoals radiocarbon ages constraining the age of deposition or abandonment of 4 alluvial terraces of the bheri river in botechaur our results show that the last two earthquakes occurred on this fault after 1860 and 640 bp respectively and accommodated slip greater than 8 m each a value corresponding to the incremental vertical offset of the terraces such events released a significant part of the slip deficit accumulated on the main himalayan thrust fault however given the geometry of this fault system as well as the date of occurrence of the last events the ruptures could be associated with major earthquakes also rupturing the main frontal thrust such as the great 1505 earthquake

no major active backthrust bounds the pir panjal range near kashmir basin nw himalaya abstract this research disputes the geomorphic data presented in dar et al 2014 and demonstrates that their data strongly conflicts with their own field evidence and also with the previous geological observations the authors have proposed a major sw dipping frontal fault that bounds the pir panjal range near kashmir basin of nw himalaya however field photographs show a very steep 86 dipping normal fault this therefore contradicts with all the morphometric indices interpretations and discussion presented because those are based on a major se dipping thrust fault that bounds pir panjal range in kashmir basin the proposed fault is a major sw dipping backthrust which primarily conflicts with the previous geological observations in kashmir basin because mostly ne dipping major thrusts are mapped in this region and presently only three major ne dipping faults the main frontal thrust mft the raisi fault rf and the kashmir basin fault kbf are tectonically active the new proposed major active thrust as suggested by the triangular facets mapped by dar et al 2014 was mapped on the basis of geomorphic evidence as a sw dipping thrust fault and field evidence shows a normal fault which utterly questions the nature and significance of the new research work

shallow crustal structure of the continental margin off nova scotia the nature of the upper sediments of the shelf and slope on a passive margin was investigated by using high quality refraction profiles recorded by ocean bottom seismometers off nova scotia in agreement with previously published reflection profiles well data and lithospheric models for the evolution of passive margins we found little thickening of the post early cretaceous section implying an even sedimentation rate over the outer shelf for this time period the velocity model determined from slant stacks agreed reasonably well with well log data but had velocities slightly lower than those found from a nearby refraction line using first arrival travel time methods starting at the sea floor the compressional velocity depth model consists of a gradient of roughly 0 4 s 1 to a depth of about 1 25 km followed by another gradient of roughly 1 s 1 to a depth of about 3 5 km beneath this depth the velocity gradient approaches zero and can be modelled as a constant velocity layer stoneley waves were us

magnitude calibration of north indian earthquakes this article is concerned primarily with the evaluation of the size and location of northern indian and southern tibetan earthquakes during the last 200 yr it draws attention to the problems of assessing intensity of early and more recent earthquakes in a built environment which is different from that for which the intensity scale has been constructed and to the way in which isoseismals are drawn through a re evaluation of intensities and a reassessment of isoseismals a formula for the estimation of surface wave magnitude using isoseismal radii is derived this formula is used to estimate the surface wave magnitudes of 16 earthquakes that occurred in the region between 1803 and 1900 this study shows that it is possible to calculate accurate surface wave magnitudes for earthquakes that occurred before the advent of the scale and that there is no need to resort to empirical formulae for the assessment of the size and seismic moment release of pre 20th century earthquakes also derived are formulae for the conversion of ms to m0 in total locations surface wave magnitudes and m0 estimates are presented for 43 important events that occurred in the region between 1803 and 1974 eight of which were in the lower crust or were subcrustal we find that the m0 ms scaling for india yields smaller ms than the global relation and that the methodology used can help to evaluate more realistic slip rates as well as to address other issues related to earthquake hazard in northern india

positive cerium anomaly in the doushantuo cap carbonates from the yangtze platform south china implications for intermediate water column manganous conditions in the aftermath of the marinoan glaciation abstract oxygenation exerted an important control on the emergence and diversification of metazoans in the aftermath of the marinoan glaciation however the relationship between the oceanic dissolved o2 do levels and early metazoan evolution remains equivocal to provide a temporal and spatial reconstruction of the redox conditions for this critical interval this study investigates the early ediacaran cap carbonate deposits within intra shelf facies at three localities in the three gorges area the yangtze platform south china trace and rare earth elements are sequentially extracted from the carbonate fraction for pristine temporal seawater signals the member ii dolostones of the duoshantuo formation which overlies the cap carbonates show a negative ce anomaly no ce anomaly is observed in the lower units of the cap carbonates in contrast positive ce anomalies ce ce 1 3 in the uppermost part of the cap carbonates are observed in all studied sections these positive ce anomalies are accompanied by high mn fe ratios ranging from 5 04 to 14 96 and slightly positive mree anomalies suggesting that a fe mn oxyhydro oxide coparticipation occurred during the cap carbonate deposition the positive ce anomalies may result from the reductive dissolution of the ce enriched mn oxyhydro oxides across a mn iv mn ii redoxcline in a distinct manganous water wedge that was sandwiched between well oxygenated and anoxic ferruginous deep water layers this wedge may have exhibited low oxygen conditions with approximately 10 m do dissolved oxygen in comparison to the 90 m do expected in an oxic setting and 0 m do in an anoxic setting therefore the presence of a positive ce anomaly in the uppermost part of the cap carbonates indicates a new intermediate manganous condition and further elucidates the water column redox structure that existed following the end of the marinoan glaciation early ediacaran metazoans were possibly restricted to fully oxygenated conditions and were absent in the manganous or ferruginous rich environments