lithofacies analysis of colluvial sediments an aid in interpreting the recent history of quaternary normal faults in the basin and range province western united states inferring the frequency and magnitude of past earthquakes from the stratigraphy in exposures of normal faulted sediments is difficult because colluvial lithofacies assemblages adjacent to faults are complex similarities in facies assemblages adjacent to young fault scarps in arid to semiarid areas such as the basin and range province allow lithofacies to be grouped into two genetic architectural elements debris and wash elements upper and lower facies associations can commonly be recognized within each element a lithofacies code scheme similar to those used in the analysis of fluvial and glacial lithofacies sequences provides a concise way of illustrating lithofacies relations in fault exposures the source lithology of colluvial lithofacies is shown in the code and soil horizon symbols can be included the architecture of lithofacies assemblages near fault scarps in semiarid areas is explained by a model of colluvial sedimentation in response to a single surface faulting event analysis of lithofacies assemblages exposed in three trenches across normal faults in the eastern basin and range shows how the model can be used to interpret fault histories similar facies analysis methods may be useful in interpreting colluvial sequences formed by non tectonic processes

shallow marine carbonate sedimentation in a tectonically mobile basin the muschelkalk middle triassic of upper silesia southern poland abstract earthquakes and resulting tsunamis are important geological phenomena however their sedimentary paleorecord is difficult to identify because some fabrics can be generated by other processes and the criteria for discrimination of seismic and non seismic triggers are not fully established this paper presents several deformation and sedimentary structures in the middle triassic carbonates of upper silesia and discusses their seismogenic and tsunami origin and controls on the deformation type intensity preservation potential and geographic distribution the deformation type and intensity were controlled by the primary lithology whereas the lateral continuity of deformed horizons depended on the lateral extent of hosted facies the thickness and abundance of these structures increase towards the krakow lubliniec fault zone which bounded the area from the east and is considered as the main epicentrum of earthquakes and tsunami initiation the discussed fabrics have a universal significance and can potentially be found in other shallow marine carbonate successions

seismic potential of the dead sea fault in the northern gulf of aqaba elat new evidence from liquefaction seismic reflection and paleoseismic data abstract the cities of elat israel and neighboring aqaba jordan are major economic cultural and seaport centers they are located on the northern shore of the gulf of aqaba elat gae directly on the dead sea transform yet the precise location of the fault trace and its tectonic activity are lacking the interpretation of seismic reflection profiles across the gae beach and paleoseismic trench data located 2 2 km north of the shoreline provide evidence that the active offshore mapped avrona fault extends onland along the eastern side of the elat sabkha mudflat where three prominent fault strands crosscut the sedimentary fill mismatch of reflector geometry across the faults and flower structures indicate strike slip faulting with a normal slip component subsurface data from two trenching sites provide evidence for a minimum of two surface ruptures and two paleoliquefaction events faulting is constrained by radiocarbon dating for an event 1 between 897 and 992 ce and event 2 after 1294 ce we suggest that the historically documented 1068 ce and at least one later earthquake in 1458 or 1588 ce ruptured the elat sabkha site based on fault mapping we suggest a minimum value of m 6 6 for the 1068 ce earthquake whereas no surface rupture was observed for the 1212 ce historical earthquake fluidized strata radiocarbon dated to before 1269 1389 ce identified as paleoliquefaction may be attributed to it two liquefaction sand blows mapped in the trench likely formed after 1337 ce and before 1550 ce which possibly occurred at the same time as in the second faulting event our data suggest that no large event occurred along the avrona segment in the past 430 550 years given a 5 mm yr slip rate we conclude that a significant period of time passed since the last surface rupturing on the avrona fault increasing its seismic potential

floodplain aggradation and pedogenesis in a semiarid environment alluvial valley fills in the upper republican river basin southwestern nebraska provide evidence for processes of aggradation and pedogenesis on semiarid cut and fill floodplains sheetflow deposition on unchanneled valley floors represents an important mechanism of valley aggradation sheetflow deposits contain parallel to sub parallel laminae and discontinuous lobate sedimentary structures rates of sediment deposition on cut and fill floodplains strongly determine the degree to which pedogenic features develop within aggrading alluvium three pedofacies common to semiarid alluvial deposits correspond with increasing aggradation rates 1 cumulic soils 2 multiple buried soils and 3 no pedogenic features radiocarbon age determinations from alluvial fills indicate that floodplain aggradation greater than approximately 0 5 cm year 1 limits soil formation this represents a threshold rate of pedogenic assimilation floodplain soils formed under aggradation rates lower than this exhibit a strong positive relationship between aggradation rate and total caco3 percent and a negative relationship between aggradation rate and organic carbon percent recognizing the associations between pedogenic sedimentologic features and floodplain aggradation rates can help interpret past rates of sediment transport storage and deposition

paleoseismic evidence for time dependency of seismic response on a fault system in the southern arava valley dead sea rift israel the elat fault system in the southern arava valley dead sea rift israel is a complex fault zone characterized by marginal normal faults and central sinistral strikeslip faults paleoseismic evidence shows that the elat fault system has generated at least 15 earthquakes of magnitudes m larger than 6 during the late pleistocene and the holocene at least two branches of the fault zone were tectonically active simultaneously indicating that the seismic response over a period of 80 k y was time and space dependent late pleistocene earthquakes displaced the surface by 1 1 5 m their magnitudes were between m 6 7 and m 7 and their average recurrence interval was 2 8 6 0 7 k y movements along the fault system in the holocene had a higher frequency and a recurrence interval of 1 2 6 0 3 k y but resulted in smaller displacement amounts 0 2 1 3 m and smaller earthquake magnitudes m 5 9 m 6 7 historical records document the last seismic event along the elat fault zone at 1000 yr ago the decrease in tectonic activity with time is inferred from the concentration of offset along the fault segments in the central part of the elat fault zone and the decreased seismicity in the eastern and western margins the magnitude range determined for the central zone m 6 1 m 6 7 was likely not high enough to activate the marginal faults the average slip rate on the normal faults is 0 2 mm yr however the slip rate has changed through time on different fault segments in the active wide shear zone and between clusters of events related to the same segment the event specific slip rates therefore have varied from 0 1 to 0 3 mm yr the decrease in earthquake magnitudes with time combined with the observations that the last large event occurred in a d 1068 and that no microseismicity has been detected during the past 15 yr might signal locking of the elat fault zone this effect if true may result from episodic global reorganization of the system s mode of strainenergy release reflected in the configurational entropy of stress states on the fault these results have significant implications for seismic hazard assessment in the southern arava valley southern israel and underscore the possibility that the elat fault may be a site of major earthquakes in the near future

plutonic rock types series discrimination of various granitoid series and related rocks abstract the streckeisen qap diagram discriminates four characteristic type series among the large variety of granitoids associated in intrusions three of them integrate varied compositions from basic to acid terms 1 the calcalkaline series with its low k or trondhiemite medium k or granodioritic high k or monzonitic variants 2 the alkaline series with its characteristic syenitic members 3 the tholeiitic series deprived of k feldspars the fourth 4 corresponds to mobilizates associated with migmatites of varied composition but always quartz rich the generalization in the qapf system allowing the plotting of undersaturated alkaline series provides an excellent visual display of the major associations and trends for the plutonic rocks

the seismicity along the dead sea fault during the last 60 000 years abstract evidence for unchanging slip rate and a gutenberg richter relation for earthquake distribution along the dead sea fault during the past 60 000 yr are presented the evidence comes from three different segments approximately 100 km apart and from three different timescales prehistoric paleoseismic historical and modern instrumental records the paleoseismic data are based on two different methods in the southern arava valley and the northern jordan valley segments the amount of normal displacement along several faults is used while in the dead sea basin the appearance of brecciated beds which are considered as seismites is used we found that for the southern arava valley segment a constant dip slip rate of 0 5 mm yr can explain the cumulative normal slip during the past 45 000 yr this suggests that normal faulting is only 10 of the total left lateral strike slip motion we also found that for all three segments the paleoseismic and historical records of strong earthquakes lie on the linear extrapolation of the frequency magnitude relation of the instrumental record the calculated b values for all three segments are between 0 85 and 1 similar to other major strike slip faults in the world it is concluded that the gutenberg richter distribution is a stable mode in the tectonic setting of the dead sea fault during the past 60 000 yr

testing thrust tectonic models at mountain fronts where has the displacement gone the alternative relationships that can exist between a mountain front and the adjacent foreland basin have been recognized for many years however seismic reflection data from such areas are commonly of poor quality and therefore structural models may contain large uncertainties in view of scientific and commercial interest in mountain belts we have reviewed the methods for discriminating between alternative interpretations using a case study from the montagna dei fiori in the central apennines italy in this area mesozoic and tertiary carbonate sediments are juxtaposed with a foredeep basin containing up to 7 km of messinian and plio pleistocene siliciclastic sediments a new structural model for this area demonstrates how the structures in this area form a kinematically closed system in which displacement is transferred from the thrust belt to blind structures beneath the present day foreland growth strata show that pliocene shortening was initially rapid 15 mm a 1 followed by slower rates during the final stages of deformation variations in structural elevation indicate a component of basement involvement during thrusting and this is further supported by magnetic modelling the results illustrate the interaction of thin and thick skinned structures in the central apennines and the methods for discriminating between alternative structural models

use of soils and colluvial deposits in analyzing tectonic events the southern arava rift israel abstract buried soils in colluvium units developed on downthrown fault blocks have been presumed to form during periods of tectonic quiescence this assumes however that all colluvial units on a fault scarp are tectonically induced particularly for a multiple event fault scarp to test this hypothesis we compared the colluvial stratigraphy and pattern of soil development on two non tectonic scarps terrace risers and a nearby multiple event fault scarp on the same alluvial fan surface both slopes developed under extremely and climatic conditions the colluvial stratigraphy and soil catenary relationship developed on terrace risers were found to be substantially different from those on the multiple event fault scarp the fault scarp colluvium contained several colluvial units separated by soils whereas only two colluvial units without buried soils were found on the terrace risers the colluvial units on the fault scarp were triangular in shape while those on the terrace riser were concave and overlapped up the slope cumulic soils indicating a continuous and low rate of deposition during pedogenesis were formed along the terrace riser in contrast buried soils indicating episodic deposition occurred on the downthrown block of the multiple event fault scarp accordingly the colluvial stratigraphy developed on the fault scarp can be viewed as a record of distinct tectonic events with no climatically controlled deposition the data indicate that soils and sedimentary stratigraphy can serve as useful indicators to distinguish terrace risers and single event fault scarps from multiple event fault scarps these indicators can be helpful in distinguishing phases of tectonic activity and in evaluating recurrence intervals on a multiple fault scarp

estimating ages of late quaternary stream terraces from analysis of weathering rinds and soils rates of growth of rock weathering rinds and rates of changes of soil morphologic and chemical properties that are calibrated at sites of known ages produce powerful tools for estimating ages of geomorphic surfaces particularly when materials datable by conventional methods are not widespread sequences of latest quaternary stream terraces from the south island of new zealand are ideally suited for application of these calibrated age techniques because climate and source materials for terrace deposits are internally consistent within two regions west land and marlborough modal and mean thicknesses of weathering rinds formed in surface cobbles of torlesse graywacke provide age estimates for latest pleistocene and holocene stream terraces in marlborough with uncertainties estimated at 5 to 40 modal rind thickness of subsurface cobbles provides age estimates for latest quaternary westland sites with uncertainties of 10 to more than 50 few dated soils are available to constrain rates of soil development in westland and marlborough furthermore soils were sampled from only one pedon on each surface morphologic data however provide least squares age estimates for westland sites with uncertainties typically greater than 100 and the calibration data can further bracket likely soil ages to less than 50 uncertainty the regression data from marlborough are less reliable but profile index ratios help bracket ages to at least 50 distributions of oxalate extractable fe and ai and total major element concentrations allow age estimates for westland and marlborough soils with uncertainties estimated at 15 to 50 despite these uncertainties the three techniques combine to provide age estimates with the high resolution needed to examine details of fault slip rates or stream downcutting the calibration data and weathering rates used herein are applicable only to the new zealand region studied although similar calibrated age techniques should provide high resolution dating in many other regions such techniques are particularly useful when multiple approaches are available to provide independent cross checks

late quaternary activity along the lone pine fault eastern california the lone pine fault is a north trending secondary break of the owens valley fault zone 1 4 km west of lone pine california this fault forms an east facing scarp as much as 6 5 m high across an abandoned outwash fan of the tioga latest pleistocene glaciation the fault experienced large right lateral and smaller vertical displacement during the 1872 owens valley earthquake knowledge of the character and amount of slip at this site in and before 1872 is necessary for evaluations of earthquake hazard near owens valley and may help us to understand earthquakes along other parts of the eastern front of the sierra nevada and in the great basin scarp profiles indicate a 1 to 2 m component of dip slip in 1872 thus three 1872 type earthquakes could have created the scarp this number of events is also indicated by desert varnish patterns on boulders in the fault scarp by scarp morphology and by sediments near the fault horizontal offset of a relict channel on the fan is 12 to 18 m 3 earthquakes horizontal offset of a younger debris flow is 10 to 12 m apparently 2 earthquakes average horizontal offset for each earthquake including that of 1872 is 4 to 6 m the age of the fan surface is bracketed by a 21 ka shoreline of former lake owens and by the time of abandonment of the fan about 10 ka an average recurrence interval for 3 earthquakes is 5 000 to 10 500 yr the average recurrence interval combined with the average oblique offset for each event of 4 3 to 6 3 m gives an average late quaternary slip rate of 0 4 to 1 3 mm yr for the lone pine fault if we add the average horizontal slip component for the lone pine fault to the 1872 horizontal slip reported for the adjacent main owens valley trace of 2 7 to 4 9 m the combined 1872 horizontal slip component for the owens valley fault zone is approximately between 7 and 11 m a large value the associated horizontal slip rate for the owens vallev fault zone is 0 7 to 2 2 mm yr

bimodal back arc alkaline magmatism after ridge subduction pliocene felsic rocks from central patagonia 47 s abstract volumetrically minor microsyenites alkali microgranite and related trachytic dykes intrude early pliocene oib like alkali basaltic and basanitic flows of the meseta del lago buenos aires in central patagonia 47 s 71 30 w and occur together with scarce trachytic lava flows whole rock k ar ages between 3 98 and 3 08 ma indicate that the emplacement of these felsic rocks occurred more or less synchronously with that of the post plateau basaltic sequence that they intrude during a bimodal mafic felsic magmatic episode devoid of intermediate compositions chemically these rocks have a1 type granitoid affinities and are characterized by high silica and alkali contents 60 68 wt sio2 8 7 10 8 wt na2o k2o major and trace elements patterns evidencing evolution by low pressure fractional crystallization and sr and nd isotopic signatures similar to those of coeval basalts 87sr 86sr o 0 70488 0 70571 143nd 144nd o 0 512603 0 512645 nevertheless some of them have the most radiogenic sr values ever reported for a magmatic rock in the meseta and even in the whole neogene patagonian plateau lavas province 87sr 86sr o 0 70556 0 70571 143nd 144nd o 0 512603 0 512608 in addition very high contents of strongly incompatible elements in the most evolved rocks together with sr isotopic ratios higher than those of coeval basalts suggest the occurrence of open system magmatic processes continuous fractional crystallization from a primitive basaltic source similar to post plateau coeval basalts towards alkali granites combined with small rates of assimilation of host jurassic tuffs afc in a shallow magmatic reservoir best explains the geochemical and petrographic features of the felsic rocks therefore a1 type magmatic rocks can be generated by open system crystallization of deep asthenospheric melts in back arc tectonic settings in central patagonia these 3 4 ma old alkaline intrusions occur aligned along a n160 170 trending lineament the zeballos fault zone stacking the morphotectonic front of one segment of the patagonian cordillera intrusion along this fault zone occurred during the onset of a new transtensional or extensional event in the area related to major regional tectonics occurring in possible relation with the collision of one segment of the chile spreading ridge with the trench

characterization and origin of aluminous a type granites from the lachlan fold belt southeastern australia the metaluminous to weakly peraluminous a type granites of the lachlan fold belt are a distinctive group of igneous rocks on the basis of chemical and mineralogical criteria those granites that contain 65 72 sio2 can be distinguished from other types on the basis of higher abundances of fetotal fetotal mg high field strength elements trivalent rare earth elements ga and zn mineralogically they contain fe rich hydrous mafic minerals and primary ilmenite and hence are reduced relative to the ni nio buffer however the extremely felsic a type granites sio2 72 have the same chemical and mineralogical characteristics as felsic fractionated i type granites recent analyses indicate that the lachlan fold belt a type granites have sc f alkali element trace transition element and h2o contents similar to those of other unfractionated i type granites rb sr and nd sm isotopic compositions are highly variable probably reflecting source region heterogeneity the metaluminous to weakly peraluminous a type granites of the lachlan fold belt are distinct from peralkaline rocks in terms of chemical composition petrography and field associations although these rocks have been grouped together as a single type in current classification schemes we propose that the metaluminous to weakly peraluminous a type granites such as those of the lachlan fold belt should be defined as aluminous a type granites and should not be grouped with peralkaline granites the lachlan fold belt aluminous a type granites have relatively high calculated zircon saturation temperatures we suggest that these granites were produced by high temperature partial melting of a felsic infracrustal source

reevaluation of holocene faulting at the kaysville site weber segment of the wasatch fault zone utah the 1978 kaysville utah trench excavated by swan and others 1980 across a large graben of the weber segment of the wasatch fault zone was reexcavated in 1988 to reevaluate the timing and nature of holocene faulting relogging of the trench reveals evidence for five or six faulting events younger than the provo phase of lake bonneville circa 13 000 14c years b p geometric reconstruction of net vertical offset in the last three events suggests a variation in coseismic vertical displacement at this site ranging from a net of 1 4 3 4 m per event the three latest faulting events occurred at shortly before 0 6 0 8 ka 2 8 0 7 ka and circa 3 8 7 9 ka earlier events cannot be directly dated because older graben fill sediments yielded thermoluminescence ages older than the time of deposition and some scarp derived colluvial wedges beneath the trench floor were not exposed the two younger faulting events we recognize at kaysville correlate reasonably well with faulting events on the same segment 25 km north near east ogden utah at circa 0 8 1 2 ka and 2 5 3 0 ka forman and others 1991 whereas the earlier kaysville event is significantly older than the earliest 3 5 4 0 ka event dated at east ogden the 3 5 4 0 ka ground rupture recognized at east ogden may have died out at a subsegment boundary between the two trench sites within the 61 km long weber segment

insights on the origin of the graciosa a type granites and syenites southern brazil from zircon u pb geochronology chemistry and hf and o isotope compositions abstract the neoproterozoic post collisional graciosa province southern brazil comprises several a type intrusions and related volcanics of alkaline and subalkaline or aluminous petrographic associations u pb age determinations trace element and hf and o isotopic compositions were obtained for zircons from six distinct a type granitic and syenitic plutons from both alkaline and subalkaline associations from the province geochronological results indicate that their emplacement petrogenetic evolution and crystallization spanned over a 9 million years interval with peak magmatism at 580 ma plutons were emplaced in a post collisional extensional regime related to the geodynamic evolution of the south southeastern part of the gondwana supercontinent hf isotopic compositions are highly variable with ehf t values between 1 4 to 31 whereas 18o signatures are mainly between 4 7 and 6 0 these features along with trace element signatures especially for hf u nb and rare earth elements suggest that generation of the graciosa rocks occurred via partial melting of a lithospheric mantle previously metasomatized by slab derived fluids followed by variable degrees of crustal contamination at depth

unraveling magmatic and orogenic provenance in modern sand the back arc side of the apennine thrust belt italy modern river and beach sands carried to and deposited along the coasts of the tyrrhenian sea are derived from multiple mag matic arc and orogenic sources including ophiolitic sequences and tur bidites issued from the ligurian ocean carbonate platform to pelagic sedimentary and metasedimentary successions originally deposited onto the adria continental margin and overlying foredeep clastic wedges undissected arc feldspatholithic signatures characterize limited areas capraia island tarquinia and napoli gulfs contrasting fea tures with respect to circum pacific suites low to very low p f ratio include sanidine as the most abundant detrital feldspar and common leucite and leucite bearing lithic fragments reflecting the potassic to ultrapotassic character of neogene quaternary magmatism green au gite associated with oxyhornblende and either abundant hypersthene tuscan magmatic province or minor olivine and spinel roman mag matic province is the dominant dense mineral dissected arc ar kosic signatures reflect unroofing of miocene monzogranitic stocks in the tuscan archipelago sands from ophiolitic sequences and remnant ocean sediments subduction complex provenance are characterized by common cel lular serpentinite with few chert grains basaltic to diabase and gab broic grains and by abundant shale to slate lithic grains respectively dense mineral suites are dominated by either diallage or chrome spinel sedimentaclastic sands ranging in composition from lithic to quartz ofelspathic are widespread thrust belt provenance richest in lith ic grains is detritus from mesozoic platform dominant carbonates with abundant dolostone to pelagic dominant limestone with abundant chert sedimentary successions metamorphiclastic sands with poly crystalline quartz phyllite and quartz mica or marble lithic grains from denuded core complexes are found locally apuane alps rela tively quartzose sands with abundant feldspars and garnet rich dense mineral assemblages are recycled from foredeep turbidites derived di rectly or indirectly chiefly from the alps this signature is foreign to the apennine accretionary wedge where continental basement is not structurally involved we calculate that one third of the sand grains deposited along tyrrhenian shores today are ultimately derived through long distance multistage transport and repeated recycling from the alps

soil catena development on fault scarps of different ages eastern escarpment of the sierra nevada california abstract in quaternary tectonic studies soils are useful for estimating the ages of both faulted surficial deposits and colluvial wedges on the fault scarp slopes soil development on sloped landforms such as fault scarps varies with position on the slope thus an understanding of catenary relations is needed to interpret the fault scarp soils discussed here are some aspects of soil catena development on fault scarps formed by late quaternary normal faulting along the eastern escarpment of the sierra nevada between bishop and lake crowley california the fault scarps are multiple event scarps formed in pleistocene glacial and fluvial deposits composed mostly of granitic clasts and vegetated primarily with the great basin sagebrush community eolian additions to the soils are minor fault scarps formed since the tioga glaciation about 10 25 ka are high 6 26 m of vertical surface offset and steep 26 38 these fault scarps have probably been ruptured by faulting at least once during the holocene the upper parts of the post tioga fault scarps are bouldery and at the lower slope positions a finer grained colluvial wedge has accumulated in contrast to the post tioga fault scarps an old fault scarp mostly formed 100 ka ago and not ruptured by faulting in at least 15 22 ka has been degraded to a more gentle slope 17 and few boulders are exposed on the surface of the fault scarp on both age groups of fault scarps some soil properties and vegetation patterns suggest that there is more available moisture at the lower slope positions than elsewhere in the fault scarp catenas soils associated with the post tioga fault scarps are generally weakly developed a bw cox profiles that become cumulative at the lower slope positions in most places the difference in soil development between the original surface and the fault scarp is small and thus is a poor indicator of the age spread between the two surfaces in contrast to the post tioga soils soils on the old fault scarp are moderately developed a bt cox profiles that are better developed on the fault scarp slope than on the original surface increased soil development on the slope may reflect higher available moisture on the slope and erosion of the original surface through time on both the post tioga and the older fault scarps buried soils within the colluvium were rarely encountered the lack of buried soils may be due to a combination of low regional rates of soil development short interseismic time intervals for events forming the scarps and on the old fault scarp overprinting of soils by subsequent weathering and soil development a comparison of soil catena development on the two age groups of fault scarps suggests that after faulting ceases pedogenesis becomes the dominant process of the fault scarp although slope processes may continue to modify the fault scarp slope they proceed at rates that are lower than the rate of soil development

stages and rate of the gravel shattering process by salts in desert reg soils abstract gravel shattering by salts is a common process in gravelly young to mature desert reg soils the shattered gravel is found on the surface and in the b and c horizons down to a maximum depth of 50 cm field studies on the process of salt weathering in deserts are scarce therefore the objectives of this study are to present the stages of development of the gravel shattering process by salts in desert reg soils and to discuss factors influencing the rate of development under natural conditions prevailing in the negev desert the studied reg soils were developed on two alluvial fan chronosequences in the negev desert the fan of nahal ze elim and the fan of nahal shehoret the development of the shattering process can be divided into five stages a e based on chemical physical and micromorphological features of the reg soils stages a d very young yo young reg soils represent the early holocene to the present some 14 000 years salinity values are between 0 27 16 mmho cm and the percentage of the shattered gravel is between 20 and 70 the shattered gravel however still maintains its original shape stage e mature reg soil represents the middle pleistocene to early holocene or 500 000 years salinity values at this stage reach 62 mmho cm although part of the gravel does not keep its original shape and starts to disperse in the profile the percentage of shattered gravel is only 75 80 it was found that the process of salt shattering in reg soils does not depend on concentrations or mineralogy of the salts but on the micro environmental conditions of the soil profile the process requires extreme and rapid variations of temperatures and moisture conditions such as found close to the soil surface to cause salt crystallization in a confined system with time the sealing of the soil surface through the development of desert pavement and a gravel free b horizon results in a change in the soil micro environment this change impedes the process irrespective of the amounts concentrations and types of salt minerals which exist in the profile the fact that in extreme arid regions the gravel shattering process develops primarily close to the reg soil surface suggests that it can be used to identify buried reg soils and to reconstruct climatic and micro environmental conditions of paleosols

surface faulting accompanying the borah peak earthquake and segmentation of the lost river fault central idaho on the morning of 28 october 1983 the ms 7 3 borah peak earthquake struck central idaho and formed a y shaped zone of surface faults that is divided into a southern a western and a northern section the total length of the surface faults is 36 4 3 1 km and the maximum net throw is 2 5 to 2 7 m the near surface net slip direction determined from the rakes of striations in colluvium averaged 0 17 m of sinistral slip for 1 00 m of dip slip the 20 8 km long southern section is the main zone of surface faulting and coincides with the thousand springs segment of the lost river fault it has the largest amount of net throw most complex rupture patterns and best evidence of sinistral slip the surface faults include zones of ground breakage as much as 140 m wide en echelon scarps with synthetic and antithetic displacements and individual scarps that are nearly 5 m high the 14 2 km long western section diverges away from the lost river fault near the northern end of the southern section the net throw on this section is generally less than 0 5 m but locally is as much as 1 6 m the new ruptures are poorly developed across the crest and north flank of the willow creek hills they are mostly downhill facing arcuate scars perhaps incipient landslides that may overlie a deeper zone of tectonic movement the northern section at least 7 9 km long is on the warm spring segment of the lost river fault and has a maximum net throw of about 1 m the pattern of surface faulting on this section is simple compared to the other sections a 4 7 km long gap in 1983 surface faults separates the northern and southern sections but contains an older scarp of late pleistocene age geologic seismologic and geodetic data from the earthquake suggest that barriers confined the primary coseismic rupture to the thousand springs segment of the fault the rupture propagated unilaterally to the northwest from a hypocenter near the southeastern end of the segment the southeastern boundary of the segment is marked by an abrupt bend in the range front a 4 km long gap in late quaternary scarps and transverse faults of eocene age that intersect the lost river fault the northwestern boundary of the thousand springs segment is at the junction of the willow creek hills and the lost river fault here the southern and western sections of surface faults diverge and there is a gap in the 1983 scarps during the first few weeks after the main shock the large magnitude and large stress drop aftershocks clustered near this barrier later aftershocks were mainly northwest of the barrier on the warm spring and challis segments and showed that strain adjustments eventually affected the entire northern part of the lost river fault fault scarp morphology and the bedrock geology suggest that the boundary between the thousand springs and warm spring segments has probably ruptured less frequently and had less net slip during much of the late cenozoic than the interior of the adjacent segments the 1983 faulting shows that although segment boundaries can stop or deflect primary ruptures secondary surface faulting can occur on adjacent segments of the main fault a late pleistocene scarp in the 1983 gap suggests that infrequent earthquakes perhaps larger than the 1983 event might break through a segment boundary and thus release strain on two adjacent segments

thermoluminescence dating of fault scarp derived colluvium deciphering the timing of paleoearthquakes on the weber segment of the wasatch fault zone north central utah the timing of middle to late holocene faulting on the weber segment of the wasatch fault zone utah is constrained by thermoluminescence tl and radiocarbon age estimates on fine grained fault related colluvial sediments the stratigraphy in two trenches excavated across fault scarps is characterized by a stack of three colluvial wedges deposited in response to three separate faulting events the oldest of which buried a soil developed on a middle holocene debris flow thermoluminescence age estimates by the partial and total bleach methods and the regeneration method on fine grained colluvium from the trenches agree within 1 sigma and are concordant with the radiocarbon chronology a synthesis of the tl and 14c age estimates indicate that these three faulting events occurred sometime between 4500 and 3500 between 3200 and 2500 and between 1400 and 1000 years ago detailed investigation of a sequence of fine grained scarp derived distal colluvium shows that much of the sediment was deposited during 600 year intervals immediately after faulting the sedimentation rate of colluvium is inferred to increase shortly after faulting and tl dating of these sediments provides additional information to constrain the timing of faulting events

late quaternary earthquake chronology from luminescence dating of colluvial and alluvial deposits of the arava valley israel abstract luminescence ages help provide a time scale for recurrent surface ruptures on a normal fault in the southern arava israel the dated samples come from alluvium and colluvium along a fault scarp north of elat the ages obtained mainly by infrared stimulation of sand size potassium feldspar grains accord with geomorphic age estimates from soils and degraded scarps four large earthquakes occurred between 37 000 and 14 000 yr ago five smaller earthquakes occurred thereafter continuing until recent times the mean recurrence interval for earthquakes of magnitudes greater than 6 is about 4000 yr

provenance of mesozoic to cenozoic circum mediterranean sandstones in relation to tectonic setting abstract the composition and stratigraphic relations of clastic strata in diverse sedimentary basins of the circum mediterranean region reflect a complete record of provenance relations since break up of pangea neo tethyan taphrogenesis and subsequent plate convergence between the two major plates of europe and africa and other related microplates of iberia adria mesomediterranean and toward to the eastern mediterranean the anatolian microplate since plate reorganization after the breakup of pangea at the end of paleozoic earliest mesozoic clastic wedges filled sedimentary basins within geodynamic settings evolving from intracontinental rifts rifted continental margins protoceanic basins arc trench basin systems remnant ocean basins foreland basin systems and intramontane and back arc basins within the circum mediterranean region the changing nature of clastic particles in these clastic wedges reflect the provenance relations from different source rocks within the spatial and temporal evolving geo puzzle terranes including relations between ophiolite bearing uplifted continental crust both shallow to deep crust terranes volcanic and sedimentary particularly carbonate strata source rocks mixed siliciclastic and carbonate shallow to deep marine clastic wedges are diffuse in many filled basin systems along the mediterranean as such as occurrence of volcaniclastic layers interbedded with siliciclastic wedges the variable mosaic of source terranes within the mediterranean region offered the possibility to investigate provenance relations with a new plane of precision and sophistication discriminating grain particles in clastic wedges using spatial extrabasinal versus intrabasinal and temporal coeval versus noncoeval distinction of detrital signals the spatial temporal approach in deciphering particles in clastic rocks has been widely used to detail the basinal dispersal pathways in different geotectonic settings wherever mixed silicate and carbonate terranes act as the major source rocks from rifted continental margins to collisional orogens

sedimentology of fault scarp derived colluvium from the 1983 borah peak rupture central idaho abstract ten undisturbed samples of scarp derived colluvium from the 1983 borah peak idaho fault scarp were subjected to laboratory grain size and fabric measurements to characterize typical colluvium from a basin and range fault scarp colluvial deposits consisted of poorly sorted pebble gravels mean diameter 0 3 to 3 75 1 2 to 13 5 mm with 25 79 matrix 4 mm stereograms of long axis orientations of 115 clasts from each colluvial wedge yielded girdle type distributions with typical eigenvalue ratios of in s1 s2 0 05 0 50 and in s2 s3 0 3 1 0 these girdle distributions indicate preferred orientation in angle of repose planes coincident with colluvial wedge depositional planes short axis stereograms display single or du l maxima with mean bearing parallel to transport direction and plunge perpendicular to the colluvial wedge surface clast fabric strength is not strongly correlated with scarp aspect corr coeff 0 03 to 0 68 or with the slope of the faulted geomorphic surface corr coeff 0 16 to 0 57 but it improves with increasing matrix content corr coeff 0 04 to 0 42 fabrics in measured wedges are weaker than those reported for other colluviums and talus and resemble fabrics in debris flows however the stronger girdle tendencies and distinct orientation subgroups in scarp derived colluvium should distinguish it from suspected debris flow deposits in fault zone exposures

constraining the timing of alluvial fan response to late quaternary climatic changes southern tunisia the evolution of the oued es seffaia alluvial fan during the last 50 000 years is analyzed in the light of chronometric data derived from ams radiocarbon and optical dating techniques these ages have enabled the temporal constraint of the distalward progression of the intersection point the upper limit of the locus of deposition which has resulted in the telescopic segmentation of the fan comparison of these data with the late quaternary climatic history of the maghreb highlights several problems of interpretation due both to our limited knowledge of regional palaeoclimates and of the response of dryland fluvial systems to climate changes however our data provide some evidence to suggest that fan incision and formation of telescopic segments occurs in response to changes from arid to less arid conditions supporting the conclusions of some of the work from other areas

soil catenas to estimate ages of movements on normal fault scarps with an example from the wasatch fault zone utah usa trenches excavated across fault scarps on a 13 ka delta surface at brigham city utah usa document four types of soil catena phenomena first the relict summit soil is eroded at the scarp crest and its components incorporated into the accumulating colluvial wedge at the scarp base second the pre faulting soil weakens laterally as it is traced scarpward beneath the colluvial wedge from a relict position beyond the scarp toe third soils developed on individual colluvial wedges and on the underlying pre faulting surface merge downslope to form a cumulative soil profile at the scarp toeslope fourth soil horizons thicken downslope probably due to the combined affect of more available moisture water infiltration and sediment accumulation two soil catenas were used to evaluate the applicability of a continuity approach to paleoearthquake dating by which percentages of total development time represented by each soil at a fault scarp footslope could be estimated the continuity approach sets total soil development at the scarp footslope including any buried pre faulting soil plus the sum development of all colluvial wedge soils corrected by a slope factor f equal to total soil development at the scarp summit soil development was characterized by profile development index pdi and pedogenic clay parameters using facies models to estimate parent material values for genetically different colluvial units and recognizing inherited soil components in colluvial wedges as parent material properties the f slope factor used to correct colluvial wedge soils for development attributable to slope position rather than age was checked by using a nearby fluvial scarp as an independent control our soil data when compared to independent age estimates imply that rates of soil development have not been constant over the last 13 ka at brigham city but rather were considerably higher than average between 13 ka and 8 3 ka higher rates are probably due to a relatively high influx of eolian dust during the late pleistocene to early holocene following the lowering of lake bonneville a large paleolake in the western usa these variable rates of soil development preclude using the continuity approach for paleoearthquake dating at brigham city however promising results showing that generally consistent f factors can be calculated for fault and fluvial scarps leave open the possibility that in areas where soil development rates have been relatively constant over the time period in question the continuity approach may be a broadly applicable method for paleoearthquake dating

estimating the ages of fault scarps in the arava israel abstract systematic age estimations for the numerous fault scarps that rupture the alluvial fans in the southern arava valley israel are rare or nonexistent here we estimate the morphologic ages of several of these faults by the fault scarp degradation method and show that the ages agree well with ages estimated by the independent earlier soil geomorphic studies the values we use for the coefficient of diffusion for the fault scarp degradation process are calibrated by a few numerical ages these ages were determined by the infrared stimulated luminescence irsl method on one of the fault scarps and are the only numerical ages in the region the morphologic ages are all in a correct stratigraphic order and in agreement with field stratigraphic relationships determined by earlier studies they indicate that the studied fault scarps range in age from the latest pleistocene to very recent times the most recent fault scarps which were analyzed are less than 2000 years old and perhaps much younger they indicate that at least two earthquakes with magnitude 6 5 have affected southern israel and jordan during that period it is emphasized that so far we have studied only a limited number of fault scarps and therefore the number of large earthquakes during the last one to two millennia is a minimum

quaternary tectonic evolution of the northern gulf of elat aqaba along the dead sea transform the northern gulf of elat aqaba is located in the transition between the deep marine basins of the gulf and the shallow onland basins of the arava valley interpretation of 500 km of high resolution seismic reflection data collected across the northern shelf reveals the tectonic structure and evolution of this transition six nne trending faults and one e w trending transverse fault are mapped slip rates are calculated based on measured offsets and age determination based on a radiocarbon calibrated sedimentation rate and a quaternary age model the most active fault is the evrona fault that absorbs most of the left lateral slip within the basin with an average sinistral slip rate of 0 7 0 3 mm yr through the late pleistocene and 2 3 3 4 mm yr during the holocene two intrabasin faults east of the evrona fault that have been inactive for the last several tens of thousands of years were mapped and motion from these faults has likely transferred to the evrona fault the basin is flanked on the west by the elat fault and on the east by the aqaba fault both faults are marked by large bathymetric escarpments based on displaced seismic reflectors we calculate a holocene vertical slip rate of 1 0 0 2 and 0 4 0 1 mm yr for the elat and aqaba faults respectively the geometry slip rates and slip history of the northern gulf of elat aqaba faults show that during the late pleistocene several intrabasin faults became dominant across the basin but that during the holocene the evrona fault accommodates most of the strike slip

provenance and evolution of miocene turbidite sedimentation in the central apennines italy abstract a study of the siliciclastic detritus within the calcareous miocene turbidite sandstones of the central apennines has elucidated the provenance of these sandstones three ratios q q f k f and mc m have been used and binary correlations of these parameters show that 1 the sandstones of the marnoso arenacea are characterized by a northern alpine supply mainly derived from metamorphic rocks and subordinately from granitic rocks 2 a secondary supply of western provenance interbedded within the marnoso arenacea shows a typical arkosic composition and suggests that granitic rocks of alpine type were associated with the ligurides 3 the urbania and serraspinosa sandstones consist of detritus derived from sources almost identical to those supplying the marnoso arenacea 4 all the sandstones of the remaining central apennine basins are characterized by a siliciclastic supply similar to the arkosic one the rare carbonate fragments can be referred to the apennine units the continuity of the alpine are in the tyrrhenian area strongly suggests a connection between the western crystalline units and turbidite sedimentation in the basins examined the crystalline units are associated with a segment of the alpine chain tectonically linked to the liguride nappes apennine source areas during the eastwards migration of the apennines deformation the crystalline units were gradually eroded during the burdigalian to early pliocene interval when the laga basin was completely filled currently the term alpine is used as synonymous with northern provenance however a detailed study carried out over ten years revealed a western alpine supply associated with an apennine source area we therefore suggest that it is necessary to distinguish a northern alpine provenance from a western alpine supply

active faulting in the dead sea rift abstract manifestations of late quaternary and holocene faulting were studied in a 500 km long segment of the dead sea transform rift most prominent are left slip faults whose characteristic physiographic features are recognizable along most of the studied segment where these faults bend or are stepped to the left rhomb shaped grabens or pull aparts are produced forming depressions in the reverse situation compressional features such as pressure ridges domes and folds form positive topographic features such structures are combined on a variety of scales ranging from a few hundred meters long to tens of kilometers normal faults sub parallel to the left slip faults produce a trough like valley along much of the dead sea transform but are most prominent along the margins of the large rhomb grabens e g the dead sea trough they apparently record a small component of transverse extension generally their motion is slow young slip did not occur along some segments during the last few 10 4 y elsewhere throws of 10 20 m at least occurred in this period the dead sea transform is seismically active the instrumental and historic records indicate a seismic slip rate of 0 15 0 35 cm y during the last 1000 1500 y while estimates of the average pliocene pleistocene rate are 0 7 1 0 cm y either much creep takes place or the slip rate varies over periods of a few 10 3 y

optical dating of tsunami laid sands abstract the ages of some tsunami deposits can be determined by optical dating a key requirement being that the deposits are derived from sediment that was reworked and exposed to daylight by tidal currents waves wind or bioturbation during the last years before the tsunami measurements have been made using 1 4 ev infrared excitation of k feldspar grains separated from samples of prehistoric tsunami sand sheets and modern analogs of tsunami source sediments at four sites in washington state and british columbia source sands gave equivalent doses indicative of recent exposure to daylight tsunami sand at cultus bay washington yielded an optical age of 1285 95 yr calendric years before a d 1995 1 at 2 this age overlaps the range of from 1030 to 1100 yr determined through a combination of high precision radiocarbon dating and stratigraphic correlation tsunami sands at three sites near tofino and port alberni on vancouver island british columbia have optical ages of 260 20 325 25 and 335 45 yr historical records and radiocarbon dating show that the sand at each of the three sites is between 150 and 400 yr old these optical ages support the hypothesis that the vancouver island sands were deposited by a tsunami generated by a large earthquake on the cascadia subduction zone about 300 yr ago

allanite and chevkinite in a type granites and syenites of the graciosa province southern brazil abstract allanite and chevkinite perrierite are important accessory phases in the granitic and syenitic a type rocks of the graciosa province southern brazil allanite ce is the main ree phase in the granites of the aluminous association which includes metaluminous to weakly peraluminous granites while chevkinite ce is the typical ree phase in the metaluminous syenites and alkali feldspar syenites and the peralkaline alkali feldspar granites of the alkaline association allanite shows complex zoning patterns but is always rich in the ferriallanite molecule and in tio 2 a compositional trait that distinguishes allanite in a type aluminous associations from allanite in calcic alkali calcic and calc alkaline granitoids normalized ree patterns show strong fractionation of heavy over light ree with la n nd n ratios between 3 and 5 and la n y n ratios between 200 and 400 primary allanite is variably affected by post magmatic transformations due to the interaction with a fluid phase and metamictization caused by radioactive decay chevkinite ce is always primary and is only present in the alkaline association the early crystallization of chevkinite indicates that the parental magmas were probably close to ree saturation the ree y abundance in chevkinite 43 49 wt is almost twice that observed in primary allanite yet the normalized patterns are similar in terms of fractionation between light and heavy ree as indicated by similar la n nd n ratios in chevkinite and allanite la n y n ratios are on average lower in chevkinite 90 300 chevkinite compositions were altered by interaction with post magmatic fluids which led to marked increase in tio 2 and a reduction in ree and fe t post magmatic allanite is present in both the alkaline and aluminous associations and corresponds to ferriallanite ce in the alkaline association and allanite y in the aluminous association compared to primary allanite post magmatic allanite ce shows smaller ree fractionation 2 n nd n 5 times chondrite the mineralogy of the rocks indicates crystallization conditions close to the titanite magnetite quartz amphibole ilmenite tmqai buffer for the aluminous association and close to the fayalite quartz magnetite fqm buffer for the alkaline association and temperatures between 800 and 900 c liquidus and ca 750 c solidus the experimentally determined stability fields for chevkinite and allanite are in agreement with the textural evidence for early chevkinite crystallization and late allanite crystallization even though allanite and chevkinite only rarely coexist in the alkaline association wherever allanite and chevkinite coexist they reveal reaction textures such that it is possible that only allanite or chevkinite is stable at any given condition the distribution of allanite and chevkinite in the alkaline association suggests that the composition of the magmas is an important control on the stability fields of these minerals a fact that is supported by the presence of primary allanite in rocks formed by processes of mixing and mingling of magmas in this sense the importance of composition on the stability of allanite and chevkinite may be larger than previously suggested

indicators of faulting events and periods of quiescence in desert alluvial fans the main objective of the present paper is to present an integrated approach to the study of faulting stages in coarse alluvial deposits the study site is the alluvial fan of nahal shehoret presently under an extremely arid regime the exposure of fault scarps on the fan surfaces enables the identification of several geomorphic indicators employed in analysing and separating faulting events and periods of quiescence a the nature of fault scarp topography b soil catenary development on fault scarps c buried paleosols in alluvial deposits d colluvial bodies e rotated clasts along fault planes these indicators enable us to determine at all sites studied the total amount of displacement to separate faulting events and the amount of their displacement per event and to evaluate scarp stability and the duration of periods of tectonic quiescence

statistical relations among earthquake magnitude surface rupture length and surface fault displacement abstract in order to refine correlations of surface wave magnitude fault rupture length at the ground surface and fault displacement at the surface by including the uncertainties in these variables the existing data were critically reviewed and a new data base was compiled earthquake magnitudes were redetermined as necessary to make them as consistent as possible with the gutenberg methods and results which make up much of the data base measurement errors were estimated for the three variables for 58 moderate to large shallow focus earthquakes regression analyses were then made utilizing the estimated measurement errors the regression analysis demonstrates that the relations among the variables magnitude length and displacement are stochastic in nature the stochastic variance introduced in part by incomplete surface expression of seismogenic faulting variation in shear modulus and regional factors dominates the estimated measurement errors thus it is appropriate to use ordinary least squares for the regression models rather than regression models based upon an underlying deterministic relation in which the variance results primarily from measurement errors significant differences exist in correlations of certain combinations of length displacement and magnitude when events are grouped by fault type or by region including attenuation regions delineated by evernden and others estimates of the magnitude and the standard deviation of the magnitude of a prehistoric or future earthquake associated with a fault can be made by correlating m s with the logarithms of rupture length fault displacement or the product of length and displacement fault rupture area could be reliably estimated for about 20 of the events in the data set regression of m s on rupture area did not result in a marked improvement over regressions that did not involve rupture area because no subduction zone earthquakes are included in this study the reported results do not apply to such zones

the evolution of holocene reg gravelly soils in deserts abstract reg soil is an aridisol developed upon a stable alluvial surface composed of sand to coarse gravel the objectives of the present study were 1 to examine the initial evolution of reg soil properties with time 2 to assess and explain the rates of development of different properties 3 to establish the suitability of different soil properties for relative age dating the time dependent soil properties examined were 1 mechanical weathering of surficial rocks and desert pavement evolution 2 chemical and biological weathering of surficial rocks 3 the thickness of soil profiles and soil horizons 4 soil texture in the different horizons 5 salts and gypsum distribution and concentration in different soil horizons 6 degree of mechanical weathering of gravel in c horizons fifteen successive surfaces of the nahal wadi ze elim sequence of alluvial fans were selected for study dead sea region israel under an extremely arid climate the sequence is of holocene age 14 000 years b p to recent the main conclusions are 1 reg soils develop rather fast in several 10 3 years since their initiation however the various soil properties developed at different rates 2 the rates of change of three soil properties decrease with time these are the texture in different horizons change in added airborne and rain washed dust salinity within the soil profile change in added salts and gypsum and the amount of mechanically shattered rocks 3 soil thickness is established rather rapidly young and older holocene soil have practically the same depth surficial weathering rates appear to remain fairly constant with time 4 in coarse gravel the evolution of reg soils is dependent on added fines and salts of airborne origin and the resultant changing hydrologic regime in the soil profile the run off infiltration ratio changes as more fines and salts are added to the soil profile and as desert pavement develops 5 surficial features and fine clay in the soil profile may be used for approximate dating of otherwise undatable holocene alluvial surfaces salts and gypsum content should be cautiously used in a rather general way

soils as a tool for estimating ages of quaternary fault scarps in a hyperarid environment the southern arava valley the dead sea rift israel abstract on the alluvial fan of nahal shehoret in the extremely arid region of the negev desert israel reg soils developed on stable alluvial surfaces in colluvium along terrace risers and in colluvial units on a complex fault scarp were compared the degree of soil profile development provided an age estimate of the surface that was faulted a maximum age estimate of the scarp or terrace riser and an estimate of the maximum recurrence intervals of faulting events irsl dates of the tectonically displaced alluvial surfaces and colluvial units at the same site enabled us to re evaluate the use of reg soils for relative dating the major faulting event started at 34 8 4 3 ka it displaced a late pleistocene surface of the nahal shehoret alluvial fan dated at 56 10 8 ka renewed fluvial activity and deposition of alluvium on the downfaulted block had almost terminated by 13 6 2 3 ka the scarp was formed during the latest pleistocene and was followed by smaller faulting events which had only minor effects on the fault scarp morphology the similarity of age estimates from irsl dating and the degree of soil development in this environment indicates that soils can be used to date surfaces and colluvial units

the composition and provenance of the tortonian and messinian turbidites in the context of the structural evolution of the central apennines along the ancona anzio line abstract the ancona anzio line is a complex tectonic system separating the umbro marchide domain from the latium abruzzi platform in the central apennines it played a decisive role in turbiditic sedimentation in the four latium abruzzi basins salto tagliacozzo liri and sacco in the tortonian and in the laga basin during the messinian petrographic studies show that the composition of the turbiditic sandstones is the same in all the basins in particular 1 k feldspar is always present in greater quantities than plagioclase 2 the rock fragments consist mainly of carbonates and granitic type rocks the provenance of the turbidites is to be found in the western areas from a fragment of the alpine chain that was associated with the ligurids nappes during the eastward migration of the apennines deformation this fragment was probably eroded gradually between the langhian and the lower pliocene with the filling in of the laga basin the presence of clasts derived from the erosion of crystalline rocks and from the ligurids nappes has been documented as early as the langhian in the basin of the marnoso arenacea during the tortonian the latium abruzzi platform was lower than the umbro marchide region and the gravity flows with western provenance were able to feed the four basins formed within the platform between the end of the tortonian and the beginning of the messinian the relative uplift of the latium abruzzi platform due to displacements along the ancona anzio line caused the cessation of turbiditic sedimentation in the basins formed within the platform the progressive eastward shift of the apennine chain favoured the migration of turbiditic sedimentation towards the outer foreland laga basin

dating the ramat saharonim late neolithic desert cult site abstract the ramat saharonim site located in the central negev desert israel consists of four shrines in a shallow valley and 30 tumuli aligned on two cuesta cliffs on the valley s sides previous assessments based on site surveys suggested a general chronological span from late neolithic period ca 5000 5500 bc through the early bronze age third millennium bc excavations in one shrine and three tumuli revealed a well constructed double wall at the shrine and seven primary adult burials in the three tumuli quartz from sediment samples post dating the construction of the burials and shrine was dated by optically stimulated luminescence osl using the single aliquot regenerative dose sar protocol and charcoal and leather samples were dated by 14 c the osl results for a burial in one tumulus are 7500 700 to 6000 600 years in a second tumulus osl ages of 2000 200 1800 170 years and a 14 c age on leather of 390 200 bc 2340 2150 cal bp imply that this burial is nabatean and that the site was used also in the hellenistic period two 14 c ages on charcoal from the shrine give an age between 5280 and 4710 bc 7230 6660 cal bp osl single aliquot ages for sediment from the shrine are highly scattered and far too old 60 000 to 12 000 years the unlikely old ages are due to insufficient resetting of the osl signal of some of the quartz grains when sand was blown onto the site indeed single grain measurements for six samples of sediment postdating the shrine show a very large range of grain ages but with a distinct young population in all samples ages calculated from these young populations average 5400 800 in better consistence with the 14 c dates and confirming our supposition that only some of the transported grains were reset at the time of deposition the combined osl and 14 c dating shows that the shrines and tumuli are contemporaneous and attributes the complex to the late neolithic this has clear ramifications for our understanding of the period and the rise of desert pastoral societies

relief inversion in the avrona playa as evidence of large magnitude historical earthquakes southern arava valley dead sea rift the arava valley section of the dead sea transform dst in southern israel is characterized by the absence of seismic activity in recent times however paleoseismic analysis of sediments in the avrona playa a pull apart basin along the dst reveals that at least six m 6 tectonic events have affected the avrona playa in the last 14 000 yr the recurrence interval of the events is approximately 2000 yr trenched normal faults and push up ridges in the playa show that the upper 2 m of the deformed sedimentary sequence consists of playa deposits with uniform soil development the deformed sediments and the soil are typical of basins with an endoreic fluvial system based on the limiting age of the sequence and the extent of soil development faulting in the playa followed by compression and uplift occurred in the last 1000 yr this most recent tectonic event displaced the surface by at least 1 m consistent with a m 6 5 earthquake this earthquake changed the morphology of the avrona playa from a closed system with internal drainage to an open basin resulting in relief inversion the seismic quiescence in the arava may indicate a seismic gap in this segment of the dst

adjustments by the charwell river new zealand to uplift and climatic changes major climatic changes and rapid local and regional tectonic movements were common in new zealand during the late quaternary and caused a diversity of adjustments in the drainage basin and piedmont reaches of the charwell river which are separated by the hope fault the onset of semi arid frigid climates during the latest pleistocene probably greatly increased hillslope sediment yields in a periglacial environment and the piedmont reach aggraded as much as 42 m on top of a broad strath with the return of humid mesic climates in the holocene sediment yields decreased as dense forests again mantled the slopes and the piedmont reach degraded as mush as 81 m dating of eleven cut and strath terraces by radiocarbon calibrated weathering rind measurements on greyawake cobbles shows the degradation rates varied greatly during the last 14 ka 1 ka 1000 yr initial degradation rates of 4 m ka 1 increased to 30 m ka 1 by 6 ka ago during a mid holocene climatic optimum since 4 ka ago degradation rates have been only 1 2 m ka 1 comparable to uplift rates in the piedmont reach inferred from marine terrace studies and the river is again cutting a broad strath each broad strath represents equilibrium conditions attained by this powerful stream during interglacial times despite episodes of being overwhelmed by climatically induced sediment yield increases during full glacial climates and having to maintain a long term degradation rate equal to the uplift rate the 75 81 m of degradation since formation of the latest pleistocene fill terrace tread is the sum of the amount of late pleistocene valley floor aggradation and the amount of regional uplift that occurred between the estimated times of major strath formation at about 30 and 0 ka the 39 m of tectonically induced degradation below the pre aggradation strath is sufficiently large that post 30 ka uplift may have doubled holocene degradation rates each of the eleven degradation terraces represents pauses of a few centuries in holocene downcutting brief equilibrium conditions were attained by streambed armoring and concurrent growth of riparian plants both processes progressively increased hydraulic roughness and the shear stresses needed to entrain streambed materials occasional floods possibly from rare cyclones derived from tropical moisture sources destroyed streambed armor and channel downcutting was renewed thus the formation of eleven equilibrium terraces can be accounted for without postulating additional tectonic perturbations or secular climatic changes

petrology and dispersal pattern in the marnoso arenacea formation miocene northern apennines abstract paleocurrent gross composition rock fragment data and heavy mineral data from the miocene marnoso arenacea formation of the northern apennines suggest six source areas five are primarily extrabasinal alpine i and ii apenninic i ii and iii and one is intrabasinal the identification of characteristic multicycle materials reinforces the idea that migration of foredeeps within a plate tectonic framework occurred in the apennines integration of petrofacies paleocurrent and sedimentary facies analysis data in the study of the marnosoarenacea depositional system has proved a very powerful method for understanding the complexity of a deep sea fan system

evolution of reg soils in southern israel and sinai abstract reg soils mostly camborthids and gypsiorthids cover some 15 of the negev and sinai deserts analytical data of seven profiles on depositional surfaces of increasing age in the negev show clear relationships between ages of surfaces and soil profile features exemplified in the development of the cambic salic and gypsic horizons the youngest soil a coarse desert alluvium soil typic torriorthent of dry wadi beds up to a few thousand years old has little profile differentiation and is generally non saline or slightly saline on the higher terraces connected with the lisan formation about 70 000 12 000 years b p clear profile differentiation and the beginning of development of cambic horizons can be discerned evident in their colour textural p differences the soils are already saline and somewhat gypsiferous both soils are not yet defined as regs because of their negligible or restricted profile differentiation reg soils on the older and higher geomorphic surfaces in the arava rift valley several hundred thousand years old have well differentiated profiles with cambic salic and gypsic horizons below their stony desert pavements typical reg soils have light coloured vesicular horizons over mellow very pale brown loam frequently with laminar structure almost completely stone free layers the reddish brown loamy to clay loam b horizons are very saline and show intensive salt weathering of gravels gypsic and petrogypsic horizons occur at depth such reg soils represent the stable surfaces and soils of deserts and were developed over a long period of desert weathering

recent faulting in the southern arava dead sea transform evidence from single grain luminescence dating abstract colluvial sediments in tectonically active areas are associated with faults and dating them is important for timing earthquakes and assessing seismic hazards in hyperarid regions organic matter for radiocarbon is scarce and the dating method of choice is luminescence however colluvial sediments are difficult to date due to the short transport distance that is commonly involved and the resulting incomplete bleaching of the sediment single grain and small aliquot measurements of fault related colluvial sediments may isolate well bleached grains and provide reliable ages of faulting events elat southern israel lies on the active dead sea transform and paleoseismic data are crucial for city planners a small fresh looking nne trending graben within the late pleistocene to holocene alluvial fan of nahal shehoret near elat was trenched to expose recently active normal faults with a stack of colluvial wedges on the footwalls samples for luminescence dating were collected near the eastern fault from the alluvial fan and from the heels less than 1 m from the fault plane and toes 2 m away from the fault plane of a stack of five colluvial wedges single grain measurements of quartz were compared with large thousands of grains and small hundreds of grains single aliquots of quartz and alkali feldspar kf kf was measured using the infrared stimulated luminescence irsl signal and the single aliquot added dose saad or single aliquot regenerative dose sar protocols large aliquots and single grains of quartz were measured using the optically stimulated luminescence osl signal and the sar protocol large and small aliquots show large scatter in equivalent dose values with a distinct population of young ages quartz large aliquot ages of samples taken from the toes of the wedges range from 5200 to 2600 years however the ages of samples taken from the heels close to the fault are in reversed order from 4300 years at the base to 13 000 years at the upper wedge this results from progressive exposure and erosion of deeper and older beds on the fault scarp with continued faulting and incorporation of older poorly bleached grains into the upper wedges only single grain measurements could isolate a distinct small population of grains that were fully bleached at the time of deposition dating the colluvial wedges to between 500 and 1300 years large aliquots ages substantially overestimated the time of faulting the single grain ages record very young faulting events which may be correlated with the known historical earthquakes of the past 1500 years

fault behavior and characteristic earthquakes examples from the wasatch and san andreas fault zones paleoseismological data for the wasatch and san andreas fault zones have led to the formulation of the characteristic earthquake model which postulates that individual faults and fault segments tend to generate essentially same size or characteristic earthquakes having a relatively narrow range of magnitudes near the maximum analysis of scarp derived colluvium in trench exposures across the wasatch fault provides estimates of the timing and displacement associated with individual surface faulting earthquakes at all of the sites studied the displacement per event has been consistently large measured values range from 1 6 to 2 6 m and the average is about 2 m on the basis of variability in the timing of individual events as well as changes in scarp morphology and fault geometry six major segments are recognized along the wasatch fault on the basis of the most likely number of surface faulting events 18 that have occurred on segments of the wasatch fault zone during the past 8000 years an average recurrence interval of 400 666 years with a preferred average of 444 years is calculated for the entire zone geologic data on the distribution of slip associated with prehistoric earthquakes and slip rates along the south central segment of the san andreas fault suggest that the m 8 1857 earthquake is a characteristic earthquake for this segment comparisons of earthquake recurrence relationships on both the wasatch and san andreas faults based on historical seismicity data and geologic data show that a linear constant b value extrapolation of the cumulative recurrence curve from the smaller magnitudes leads to gross underestimates of the frequency of occurrence of the large or characteristic earthquakes only by assuming a low b value in the moderate magnitude range can the seismicity data on small earthquakes be reconciled with geologic data on large earthquakes the characteristic earthquake appears to be a fundamental aspect of the behavior of the wasatch and san andreas faults and may apply to many other faults as well

the serra da graciosa a type granites and syenites southern brazil part 2 petrographic and mineralogical evolution of the alkaline and aluminous associations abstract the serra da graciosa granites and syenites comprise five distinct plutons in the brasiliano pan african graciosa a type province southern brazil six petrographic series can be identified in these plutons 1 alkaline series 1 composed of amphibole bearing alkali feldspar syenites with varied mafic mineralogy and quartz contents from alkali feldspar syenites with calcic amphibole clinopyroxene olivine and allanite to alkali feldspar quartz syenites with sodic calcic amphibole and chevkinite perrierite and to alkali feldspar granites with sodic amphibole 2 alkaline series 2 characterized by amphibole bearing alkali feldspar granites with limited modal variations but amphibole compositions also varying from calcic to sodic 3 alkaline series 3 of limited occurrence which includes alkali feldspar syenites with olivine and clinopyroxene and no amphibole 4 aluminous series 1 of widespread occurrence with various petrographic facies of biotite granites with amphibole 5 aluminous series 2 characterized by alkali feldspar granites with biotite and only minor amphibole 6 monzodiorites typically with biotite calcic amphibole and augitic clinopyroxene partially mingled with granitic magmas the mafic minerals present are in general fe rich with correspondingly low mg and al contents in alkaline series 1 amphiboles crystallized in progressively more oxidizing and alkaline conditions while in alkaline series 2 the initial conditions were somewhat more oxidizing and shifted to reducing in the final stages in aluminous series 1 and aluminous series 2 amphiboles are calcic and comparatively homogeneous the amphiboles in the monzodioritic rocks while also homogeneous are more mg rich and show compositions quite distinct from the calcic varieties in the other associations and this is also the case for clinopyroxene mg in biotite decreases from the monzodioritic rocks to aluminous series 1 and further to aluminous series 2 contrasting evolution of the various associations suggests that several coeval magmatic series are present in the serra da graciosa granites

an indication of time dependent seismic behavior an assessment of paleoseismic evidence from the arava fault israel abstract we discuss the implications of 56 kyr of paleoseismic data from a fault on the southern segment of the arava fault system in israel at least nine events are evident beginning 37 ka we study in detail the frequency magnitude relation for the fault and develop a bayesian analysis to compare the characteristic earthquake ce model and the gutenberg richter gr model our analysis leads to the conclusion that there was a change in seismic behavior at about 14 ka from 37 ka to 14 ka the seismic activity is best described by the ce model from 14 ka to the present there is no strong indication favoring one model over the other the earthquake record is somewhat more consistent with the classical gr equation than with the ce model if one does assume that the ce model is appropriate for the younger episode then there is evidence of a change in the characteristic magnitude thus there is evidence of a change in earthquake behavior on the fault segment 14 ka

the serra da graciosa a type granites and syenites southern brazil part 3 magmatic evolution and post magmatic breakdown of amphiboles of the alkaline association amphiboles are the main mafic minerals in most metaluminous to peralkaline alkali feldspar granites and syenites and they usually preserve an important record of the compositional evolution of the melts from which they crystallize in the alkaline association of the serra da graciosa a type granites and syenites southern brazil amphibole compositions span a large range including calcic sodic calcic and sodic amphiboles calcic amphiboles are typically observed in the metaluminous rocks while sodic amphiboles are characteristic of the more strongly peralkaline rocks sodic calcic amphiboles are found in intermediate varieties compositional variations record the differentiation trends within two petrographic series of the alkaline association the overall evolution of amphibole compositions is similar in both they reveal a progressive increase in na and fe3 with differentiation increase in alkalinity of the magmas a characteristic shared by undersaturated peralkaline or agpaitic differentiation trends in detail however the evolutions of the amphibole compositions in the two series are distinct in alkaline series 1 the cores of the crystals form a continuum from calcic to sodic compositions with the exception of a small compositional gap within the sodic calcic amphiboles the rims however show compositions that diverge from this main trend this divergence results from increasing amounts of the oxy amphibole component and reflects more oxidizing conditions at the final stages of magmatic crystallization in alkaline series 2 these oxidation trends are much more subtle and a reverse trend is observed in the sodic amphiboles sodic calcic amphiboles are in several cases replaced by intergrowths of post magmatic sodic amphibole and al poor tetrasilicic biotite

gps measurements of crustal deformation across the southern arava valley section of the dead sea fault and implications to regional seismic hazard assessment abstract detailed analysis of crustal deformation along the southern arava valley section of the dead sea fault is presented using dense gps measurements we obtain the velocities of new near and far field campaign stations across the fault we find that this section is locked with a locking depth of 19 9 7 7 km and a slip rate of 5 0 0 8 mm yr the geodetically determined locking depth is found to be highly consistent with the thickness of the seismogenic zone in this region analysis of instrumental seismic record suggests that only 1 of the total seismic moment accumulated since the last large event occurred about 800 years ago was released by small to moderate earthquakes historical and paleo seismic catalogs of this region together with instrumental seismic data and calculations of coulomb stress changes induced by the 1995 mw 7 2 nuweiba earthquake suggest that the southern arava valley section of the dead sea fault is in the late stage of the current interseismic period

quaternary transform kinematics constrained by sequence stratigraphy and submerged coastline features the gulf of aqaba abstract the dead sea fault system dsfs steps over at the northern head of the gulf of aqaba goa crossing the evolving continental shelf we report detailed processing and interpretation of high resolution sub bottom profiles of the north western tip of the goa down to a depth of about 120 m our data reveal stepping seafloor morphology comprising a series of relict coastline features primarily fossil reefs whose present depth results from the combined effect of sea level rise and tectonic displacements on the northern slope the fossil reefs are embedded in a predominantly single phase 30 m thick retrograde sedimentary stack that evolved presumably during sea level rise since the last glacial maximum about 20 ka large variations in character within this sedimentary stack bear evidence for large episodic changes in the rates of sea level rise and ensuing environmental conditions during the holocene a prominent terrace and face a suggested relict coastline feature accommodated on the order of 10 m down to the east vertical offsets across the surveyed area at the north western goa since submergence presumably late pleistocene to early holocene the trace of an active strike strike slip fault crossing the northern slope is defined by a ne striking bathymetric features b discontinuities offsetting the sedimentary layering from just below the sea floor to the deepest layers imaged c a 30 10 m sinistral and 10 1 m down to the west offset of a fossil reef at a depth of about 65 m global sea level curves constrain the age of the 65 m deep reef to 11 5 2 ka yielding an estimated average holocene sinistral slip rate of 2 7 1 5 mm yr about half the regional slip of the dsfs we conclude that the submarine fault defined here is a principal strand of the dsfs a southward left stepping echelon of the avrona fault such secondary echelon segmentation may be typical for the accommodation of strike slip at tips of transform basins

luminescence dating of fault related alluvial fan sediments in the southern arava valley israel abstract infrared stimulated luminescence irsl from coarse grained alkali feldspars was used to date alluvial and colluvial deposits from nahal shehoret situated in the hyperarid southern arava valley israel late pleistocene gravelly and sandy wadi deposits associated with fault related colluvial sediments were exposed in trench 17 t 17 which was excavated across a distinct fault scarp deposition of the lower alluvial beds in t 17 took place between 90 and 100 ka this was followed by the first period of tectonic activity and by erosion the age of the upper alluvial bed ranges from 75 to 60 ka a period of stability and reg soil formation was then followed by two scarp forming faulting events resulting in colluviation the colluvium deposited after the second event was dated to 36 ka modern colluvial sediments from nahal shehoret have residual irsl ages of a few hundred years whereas modem alluvial sediments have ages of a few thousand years colluvial sediments may therefore be more suitable for luminescence dating in arid regions

is the jericho escarpment a tectonic or a geomorphological feature active faulting and paleoseismic trenching abstract the jericho fault is considered to be the main active fault in the northern dead sea lower jordan valley in previous studies it has been identified by a prominent linear topographic escarpment that is thought to be the surface expression of this fault on land north of the dead sea in this study the paleoseismic natures of the escarpment and the fault were examined seismic activity was investigated in a series of three trenches excavated south of the fault trace on the surface these trenches show evidence for late holocene faulting a fourth trench excavated 300 m farther to the south exposed continuous finely laminated marl from the 80 ka samra formation at a depth of 2 0 6 m below the surface with no evidence of faulting this could suggest that the fault on land is segmented and that the nature of its activity changes from north to south toward the lake indeed the continuation of this fault under the waters of the dead sea reveals active faulting along a sharp segmented linear bathy

evolution of magmatic afm mineral assemblages in granitoid rocks the hornblende melt biotite reaction in the liberty hill pluton south carolina

systematic mineralogical diversity in a type granitic intrusions control of magmatic source and geological processes the origin and causes of mineralogical diversity of a type granites are debated the series of a type granite plutons with distinct mineralogical differences emplaced along an upper paleozoic crustal scale shear zone in the cobequid highlands nova scotia provide an opportunity to examine the origin of different a type plutons in a similar tectonic setting based on the ferromagnesian minerals present the plutons are classified into sodic granites with sodic amphibole calcic granites with calcic amphibole and biotite granites sodic and calcic granites occur exclusively in complex intrusions with subequal amounts of gabbro in the eastern shear zone whereas plutons in the western shear zone with lesser gabbro are solely biotite granites trace elements and radiogenic isotopes show that the three granite types have different sources intensive parameters including temperature pressure and water in melt contents were estimated from mineralogical and geochemical data modeling of these geochemical data suggests that the biotite and calcic granites were derived by 20 40 partial melting of intracrustal feldspathic rocks whereas the sodic granites are extreme fractionates 90 of coeval mafic magma we propose that supply of upper paleozoic mafic magma probably related to regional extension and decompression melting beneath the magdalen basin created a deep crustal hot zone in the eastern cobequid highlands and extreme fractionation of underplated mafic sills produced the sodic granites heat transfer from crystallizing mafic magma induced partial melting of the surrounding crust creating batches of biotite and calcic granitic melts in different depths fractionated and crustally derived melts segregated along crustal scale faults constructing the complex plutons in the east melting of the crust was further facilitated by the release of water from the crustal rocks upon heating in the eastern shear zone water was released predominantly by magmatic rocks and in lesser amounts compared to the west where neoproterozoic sedimentary and volcaniclastic rocks are more abundant the volatile rich granitic melts in the western part of the shear zone were crystallized rapidly stabilizing only biotite this study demonstrates that the mineralogical variations in a type granites arise from rather similar magma compositions but they are important petrogenetic indicators of varying sources specific magmatic processes and emplacement conditions

late quaternary weathering erosion and deposition in nahal yael israel an impact of climatic change on an arid watershed in their seminal paper in 1979 bull and schick proposed a conceptual model for the geomorphic response to pleistocene to holocene climate change based on the hyperarid nahal yael watershed in the southern negev desert in this model the change from semiarid late pleistocene to hyperarid early holocene climates reduced vegetation cover increased the yield of sediment from slopes and accelerated aggradation of terraces and alluvial fans the model is now over 30 yr old and during this time chronologic paleoenvironmental and hydrogeomorphic research has advanced here we reevaluate the model using data acquired in nahal yael over the 30yr since the original model was proposed recent studies indicate that the late pleistocene climate was hyperarid and a transition from semiarid to hyperarid climates did not occur the revised chronology reveals a major 35 20 ka episode of accelerated late pleistocene sediment production on slopes with lower rates probably already at ca 50ka due to increased frequency of wetting drying cycles caused by frequent extreme storms and floods between 35 and 27 ka without lag time these sediments were transported and aggraded in depositional landscape components fluvial terraces and alluvial fans this intensified sediment production and delivery phase is unrelated to the pleistocene holocene transition the depositional landforms were rapidly incised between 20 and 18 ka since and or soon after this last glacial maximum lgm incision most material leaving the basin originated from sediments stored in depositional landforms and was not produced from bedrock using these new data we propose a revision to the bull and schick model in this hyperarid environment our revision suggests that the model should include the frequent storms and floods responsible for a late pleistocene pulse of intense weathering due to numerous cycles of wetting and drying on slopes and coeval sediment transport to fluvial terraces and alluvial fans we also discuss the common use and pitfalls of using the bull and schick conceptual model to explain observations in diverse arid environments usually without sufficient data on basin specific stratigraphic chronologic paleoenvironmental and paleoclimatic information

surface ruptures induced by the devastating 1068 ad earthquake in the southern arava valley dead sea rift israel abstract the elat fault a segment of the dead sea transform runs along the southern arava valley part of the dead sea rift israel forming a complex fault zone that displays a time dependent seismic behaviour paleoseismic evidence shows that this fault zone has generated at least 15 earthquakes of magnitude larger than m 6 during the late pleistocene and the holocene however at present the elat fault is one of the quietest segments of the dead sea transform lacking even microsesimicity the last event detected in the southern arava valley occurred in the avrona playa and was strong enough to have deformed the playa and to change it from a closed basin with internal drainage into an open basin draining to the south paleoseismological geophysical and archaeological evidences indicate that this event was the historical devastating earthquake which occurred in 1068 ad in the eastern mediterranean region according to the present study this event was strong enough to rupture the surface reactivate at least two fault branches of the elat fault and vertically displace the surface and an early islamic irrigation system by at least 1 m in addition the playa area was uplifted between 2 5 and 3 m along the eastern part of the elat fault shear zone such values are compatible with an earthquake magnitude ranging between m 6 6 and 7 since the average recurrence interval of strong earthquakes during the holocene along the elat fault is about 1 2 0 3 ky and the last earthquake occurred more about 1000 years ago the possibility of a very strong earthquake in this area in the future should be seriously considered in assessing seismic hazards

soil evolution and origin of landscape in a late quaternary tectonically mobile setting the po plain northern apennines border in lombardy italy abstract the interactions among quaternary paleo soil forming erosion re deposition and geomorphic processes at the origin of the present day landscape are discussed at three isolated tectonic reliefs of the southern po foredeep basin of lombardy san colombano casalpusterlengo and zorlesco reliefs italy these sites offer the possibility to combine different scales of geopedological geomorphological stratigraphic and structural observations to unravel the contribution of climate and tectonics to the quaternary geological evolution and to the origin of the landscape field surveys laboratory analyses and soil micromorphology were used to characterize the late quaternary pedogenic processes acting on different paleo surfaces in combination with the detailed study of seven selected soil profiles pedo stratigraphic correlations revealed that two alluvial loess paleosol sequences which originated from the late pleistocene to holocene glacial interglacial fluctuations are differently preserved throughout the present day hill landscape in situ paleosols allowed to localize the paleo topographic surfaces of geomorphic tectonic and sedimentary stabilization redeposited paleosols occurring systematically close to the main faults and or at the erosional bottom of paleo valleys allowed to mark the stages of tectonic instability the integrated approach contributed to unravel the composite nature and rank of the stratigraphic boundaries polycyclic loess soil aggradation characterized the stable paleo highs uplifted during different phases of active thrusting of the northernmost emilian arcs of the apennine while valley incision fluvial terracing soil truncation and redeposition occurred in the intervening structural lows in the san colombano hill area late pleistocene transtensional faulting induced changes of the drainage network and enhanced redeposition of paleosols in colluvial wedges on the hangingwalls along the fault scarps lgm loess was preserved above different dissected remnants of the paleo topography composing the hilltops these new constraints permit to refine the late quaternary tectono depositional history and landscape evolution at the southern margin of the po basin