the early permian floras of prince edward island canada differentiating global from local effects of climate change new permian plant specimens are described from prince edward island canada they include attached specimens of leaf and stem genera walchia and tylodendron enabling reconstruction of this early permian conifer al though poorly preserved the study of these floras extends our knowledge of diversity and climate conditions in the re gion by placing these findings in a broader stratigraphic and geographic framework we can document the phytogeographic and climate trends through the carboniferous and permian in the maritimes basin combined data on temporal trends in climate sensitive sediments as well as macrofloral and microfloral diversities generally match the independently derived paleolatitudinal estimates these show the region migrating from the southern subtropics across the equator and into the northern subtropics between the early carboniferous and early permian evaporites and pedogenic carbonates together with low diversity floras match its subtropical position in the early carboniferous in contrast coals are present in the late carboniferous accompanied by high diversity macro and microfloral remains when the region was on or near the equator however the subsequent transition to pedogenic carbonates eolian sands and lower diversity floras is not matched by significant poleward latitudinal motion we ascribe these changes to a de crease in moisture availability as transgressions of epeiric seas became less frequent and finally stopped altogether causing an increase of continentality in euramerica resume cet article decrit de nouveaux specimens de plantes datant du permien provenant de l ile du prince edouard canada ils comprennent des specimens de feuilles et de tiges rattachees de genre walchia et tylodendron permettant la reconstruction de ce conifere du permien precoce bien que ces flores soient mal preservees leur etude etend nos connaissances de la diversite et des conditions climatiques de la region en placant ces decouvertes dans un cadre stratigraphique et geographique plus large nous pouvons documenter les tendances phytogeographiques et clima tiques du carbonifere et du permien dans le bassin des maritimes des donnees combinees sur les tendances temporel les dans des sediments sensibles au climat et des diversites relatives a la macro et a la microflore concordent generalement avec les estimations de paleoaltitude derivees de facon independante ces donnees montrent qu entre le carbonifere precoce et le permien precoce il y eut une migration des regions subtropicales meridionales par dela l equateur vers les regions subtropicales septentrionales des evaporites et des carbonates pedogenetiques avec des flo res faiblement diversifiees correspondent a sa position subtropicale au carbonifere precoce par contre on retrouve des charbons au carbonifere tardif accompagnes de restes de macro et de microflores grandement diversifiees lorsque la region etait a ou pres de l equateur toutefois la transition subsequente a des carbonates pedogenetiques a des sables eoliens et a une diversite florale moindre n est pas correlee par un mouvement meridien significatif vers le pole nous attribuons ces changements a une reduction de l humidite disponible alors que les transgressions des mers epicontinen tales devenaient de moins en moins frequentes et qu elles ont finalement cesse tout a fait causant une augmentation de la continentalite en euramerique

reconstructed tree fern alethopteris zeilleri carboniferous medullosales abstract from a smaller open pit area in the roof shale of the basal cantabrian coal seam in sydney coalfield cape breton island nova scotia canada large amounts of the pteridosperm foliage alethopteris zeilleri ragot were found this foliage is associated with abundant naked medullosalean axes and dichotomies of varying sizes up to 0 80 m long cauline structures 0 90 m and 1 3 m long detached ovules assigned to pachytesta incrassata brongniart rare male pollen organs of the type dolerotheca halle rooted tree ferns in life position and one specimen each of a juvenile medullosalean frond and root mantle the fossils are compression impression preserved and the foliage yielded thickly cutinized cuticles with unoriented cells 57 103 by 27 57 m in intercostal fields ultimate rachises and abaxial surfaces excluding costal fields show a mixture of simple and complexly branched trichomes and two different structural bases these together with fractal dimensionality of curvatures of anticlinal walls in intercostal fields have taxonomic potential for alethopterids the finds suggest reconstructing a zeilleri ragot as a tree 5 7 m high that bore both p incrassata brongniart and dolerotheca type fructifications its habitat was low land coastal plains in the pennsylvanian coal swamps of ancestral sydney coalfield

chemometric study of functional groups in different layers of trigonocarpus grandis ovules pennsylvanian seed fern canada abstract we examined four dispersed coalified ovules trigonocarpus grandis of medullosalean seed fern affinity from the late pennsylvanian age sydney coalfield canada which represent the larger type of the 7 8 cm trigonocarpalean form species at first glance it appears that the ovules are preserved like the usual carboniferous foliar compressions i e one coalified layer with one preserved anatomical tissue the cuticle however careful sample preparation uncovered at least three coalified layers and schulze s oxidative maceration process which dissolves the coalified material revealed several tissue layers altogether eight sample forms were defined i coalified layer ii cuticle a iii cupric vitrain iv vitrain v cupric vi cuticle b vii alkaline solution and viii added coal seam material the purpose of the study was twofold first to systematically analyze the forms by way of fourier transform infrared ftir spectrometry to fill a gap in chemical information that exits for coalified trigonocarpalean ovules of carboniferous seed ferns second to use principal component analysis to focus on groupings as a function of chemical structure functional groups and to assess the different fossil forms in terms of ftir chemical parameters based on a 8 49 data matrix results include distinction among the three coaly sample forms coalified layer i cupric vitrain iii and cupric v based mainly but not exclusively on differences in carbonyl content as well as length and branching of the polymethylenic chains important to note is the high aliphatic content of the cuticles as a signature of the biomacromolecules cutan cutin in particular new insights into the structure of the original ovule are presented and differences in chemistry are mainly a result of the complex structure of the precursor plant organ

a comparative analysis of some late carboniferous basins of variscan europe vegetation diversity and pattern changes and their relation to tectono sedimentary histories are compared between selected euramerican late palaeozoic coalfields to understand better the controls on the dynamics of the pennsylvanian terrestrial ecosystems and to demonstrate the problems with comparing data from various basins the analysis is based on data from the following basins of different geotectonic and palaeogeographical positions the cratonic pennines basin the foreland south wales and upper silesia basins and the fault related intra sudetic and central and western bohemia basins the analysis indicates that complex factors are responsible for changes in plant diversity and vegetation patterns these are related to climate tectonics preservation potential sampling biases and the current state of revision of the flora in each basin plant diversity patterns in the basins differ because of local controls and or the character and detail of the available data maximum diversity varies among the basins within the langsettian and duckmantian substages two apparent step like drops in diversity were detected within coal bearing strata of most basins at the duckmantian bolsovian boundary and at the bolsovian asturian boundary further and more prominent falls are related to transitions from coal bearing to non coal bearing mostly red bed strata or vice versa during stephanian times interpretation of climatic signals recorded in the sedimentary successions indicates that westphalian and middle stephanian times were wet intervals whereas early and late stephanian times were drier

latest mid pennsylvanian tree fern forests in retrograding coastal plain deposits sydney mines formation nova scotia canada a latest mid pennsylvanian early cantabrian tree fern forest is reported from cape breton island nova scotia the fossil forest is rooted below the point aconi coal seam of the sydney mines formation at cranberry head the tree ferns are preserved in the deposits of a coastal plain subject to brackish incursions they were constructed of psaronid type trunks and massive pecopterid fronds and locally intergrew with sigillarian lycopsids neuropterid pteridosperms and calamiteans basal stump diameter measurements including the root mantle range from 12 to 89 cm indicating that the ferns were mostly large forest trees rather than shrubs stump distribution measurements on palaeosols indicate that localized patches of tree fern dominated forest attained densities of c 3850 trees per hectare when scaled up to standard forestry units much denser than typical mid pennsylvanian lycopsid forests tree ferns dominantly grew in aggrading floodbasin settings and a few of the largest trees show evidence for post burial regeneration being approximately coeval with the late mid pennsylvanian extinction event which resulted in tree fern forests rising to dominate tropical lowlands for the first time the cranberry head fossil forests provide insight into community composition and structure during a critical phase of ecosystem reorganization

foam rubber modeling of topographic and dam interaction effects at pacoima dam a study of the topographic and dam interaction effects was made using a 3 d foam rubber model of the actual topography around the pacoima dam accelerograph which recorded over 1 g high frequency horizontal ground accelerations during the 1971 san fernando earthquake scaling of frequency from the model to the earth depends on the average value of shear wave velocity in the upper few hundred meters assuming e 2 km sec for vertically incident sh waves the spectral ratio of the ground acceleration on the ridge to the free field flat surface indicates an amplification of about 60 per cent around 6 5 hz on the n76 w component topography has little effect upon the motion recorded on the s14 w component motion on the ridge is lower than the free field motion on both horizontal components for frequencies above 9 hz amplification peaks shift to higher or lower frequencies depending on the assumed shear wave velocity in the upper few hundred meters results from nonvertically incident sh waves show that the topographic effect is dependent on the direction of approach of the seismic energy the effect is either de amplification in part by shadowing or amplification relative to the case where no topography is present depending on whether the canyon is on the ray path or not the fourier spectrum of the ground motion at the dam crest shows peak frequencies at about 5 hz and 10 hz resonance which correspond to the normal modes of the dam a study of dynamic interaction between the pacoima dam and the ridge shows that the coupling is less than 2 per cent at about 10 hz and less than 12 percent at about 5 hz

empirical analysis of strong ground motion from the 1992 landers california earthquake a total of 167 ground level accelerograms recorded during the 28 june 1992 ms 7 6 mw 7 3 landers california earthquake were used to study the dependence of peak horizontal acceleration and 5 damped horizontal response spectra on distance azimuth and site geology a comparison of these recordings with ground shaking amplitudes predicted by contemporary attenuation relationships indicated that 1 relationships developed prior to the landers earthquake did a reasonably good job at predicting the landers ground motions within about 60 km of the fault but underpredicted the ground motions at further distances by as much as a factor of 2 to 3 and 2 relationships developed after the landers earthquake did a reasonably good job at predicting the landers ground motions within the distance ranges for which they were applicable an extrapolation of near source attenuation rates based on the newer relationships was found to significantly underpredict the landers ground motions at distances beyond about 60 km indicating a need to develop attenuation relationships that can account for differing rates of attenuation at near source and far source distances peak accelerations and response spectra were found to be significantly affected by source radiation pattern source directivity and site geology with higher ground motions observed in the direction of rupture propagation and lower ground motions observed on rock beyond distances of about 40 km regression analyses of the landers recordings indicated an unusually low rate of attenuation controlled primarily by recordings obtained at distances greater than about 60 km which can be attributed to one or more of the following factors 1 a change in geometric attenuation rate as a result of the dominance of surface waves 2 amplification in the los angeles basin the san fernando valley the san bernardino valley and the coachella valley because of the effects of deep sediments and basin response and 3 the arrival of critical reflections off the base of the crust moho the fault normal components of response spectra at sites located closest to the fault were found to be systematically larger than the fault parallel components at periods of 1 sec and greater this effect was largest at stations located north of the epicenter in the direction of rupture propagation and indicates a need to account for this effect in the design of long period structures

preliminary magnetostratigraphy of a thick eolian red clay loess sequence at lingtai the chinese loess plateau magnetic remanence and bulk susceptibility measurements are reported for a 305 m eolian loess red clay sequence at lingtai the chinese loess plateau polarity zonation defined by about 680 remanence data yields a basal age of about 7 05 ma for the section which represents the oldest wind blown dust deposited continuously in north central china during the late cenozoic the resultant magnetostratigraphic scheme implies a nearly linear accumulation rate about 2 98 cm ka of atmospheric dust on the loess plateau during the period of 7 05 to 2 58 ma comparison of the bulk susceptibility record with the pedogenic characteristics of the red clay observed in the field suggests that magnetic susceptibility in the red clay is not as useful as in the loess soil sequence to indicate summer monsoon variations

palynological evidence for pennsylvanian extra basinal vegetation in atlantic canada abstract pollen preserved in latest westphalian and early stephanian clastic deposits of the sydney coalfield cape breton island suggest that there were zones of different vegetational habitats surrounding the wetlands where the coal forming peat was formed on the margins of the wetlands was a narrow band with large cordaitanthacean trees this was surrounded by occasionally dry9 habitats supporting schuetzia plants ruflorioid plants and aethophyllum like herbaceous conifers around this were mesic or seasonally dry habitats dominated by walchian conifers and disaccate producing peltasperms these in turn were surrounded by xeric or seasonally wet habitats dominated by ullmanniacean like conifers cycads and monosaccate producing peltasperms during latest westphalian and early stephanian times the mesic and xeric habitats encroached nearer the wetlands although the vegetation of the wetlands themselves remained essentially unaffected this vegetation change was not a response to climate change but probably to changing drainage patterns and topography in the surrounding hinterland the florinites producing cordaitanthaceans appear not to have been upland trees as previously suggested but occupied mainly coastal habitats or riparian habitats on the margins of the wetlands

ecological changes in pennsylvanian asturian and early cantabrian coal floras inferred from lycophyte microspore abundances abstract the distribution and relative amounts of six genera of lycophyte microspores lycospora densosporites crassispora cirratriradites endosporites and cadiospora are compared in the pennsylvanian coals from the dobrudzha and forest of dean coalfields clastic sediments from the glace bay borehole in the cape breton coalfield and the southern crop of the south wales coalfield inverse relationships are shown between lycospora and densosporites and between lycospora and crassispora in samples from all of the coalfields the changes in microspore assemblages suggest there were at least five different communities of lycophyte plants growing in the pennsylvanian swamps changes in microspore assemblages at the asturian cantabrian boundary mirror the previously described macrofloral changes at this time

wind blown origin of the pliocene red clay formation in the central loess plateau china abstract in order to determine the depositional processes of the pliocene red clay formation deposited directly beneath the plio pleistocene loess in the chinese loess plateau four red clay sections spanning over 400 km are studied grain size analysis of closely spaced samples in the sections shows that the particles of the red clay are very fine with the sand fraction 63 m being negligible and that all the curves indicating changes in different grain size parameters have a similar pattern the grain size records in the upper part of the four sections are almost identical with the median grain size centered at 4 8 m the ree patterns of 28 samples from the jiaxian red clay section are all characterized by lree enrichments relatively flat hree and slight negative eu anomaly being similar to those of eolian loess and the average upper continental crust these lines of evidence point to a wind blown origin of the red clay deposits accumulation of the loess soil sequences in the chinese loess plateau during the past 2 6 ma can be therefore regarded as the continuation of the pliocene atmospheric dust deposition observations of spatial grain size changes in the loess plateau suggest that the eolian red clay might be transported mainly by the westerlies differing significantly from the overlying loess that was transported essentially by the east asia winter monsoonal winds

empirical green s function analysis of recent moderate events in california i use seismic data from portable digital stations and the broadband terrascope network in southern california to investigate radiated earthquake source spectra and discuss the results in light of previous studies on both static stress drop and apparent stress applying the empirical green s function egf method to two sets of m 4 6 1 events i obtain deconvolved source spectra estimates and corner frequencies the results are consistent with an 2 source model and constant brune stress drop however consideration of the raw spectral shapes of the largest events provides evidence for a high frequency decay more shallow than 2 the intermediate f 1 slope cannot be explained plausibly with attenuation or site effects and is qualitatively consistent with a model incorporating directivity effects and a fractional stress drop rupture process as suggested by haddon 1996 however the results obtained in this study are not consistent with the model of haddon 1996 in that the intermediate slope is not revealed with egf analysis this could reflect either bandwidth limitations inherent in egf analysis or perhaps a rupture process that is not self similar i show that a model with an intermediate spectral decay can also reconcile the apparent discrepancy between the scaling of static stress drop and that of apparent stress drop for moderate to large events

site resonance from strong ground motions at lucerne california during the 1992 landers mainshock analog station luc near lucerne california recorded strong motions from the nearby 1 25 km fault rupture during the 28 june 1992 landers mainshock the records illustrate general issues that can arise at near field stations in the area of the station weathered granite regolith with 400 m s s wave velocity overlies intact granite with 3000 m s s wave velocity a strongly reverberating signal persisted for several seconds after near field velocity pulse passed recovery of the vertical record in digital form provided calibration of resonant site properties and qualitative separation of site and source effects the dominant signal on the vertical spectrum arises from vertically reverberating p waves in an 13 5 m thick layer horizontal spectra marginally resolve the analogous resonance for vertical s waves and coupling of vertical p waves into horizontal motion here resonant amplification of a broad high frequency band 5 40 hz by a factor of a few over lower frequencies sufficed to dominate acceleration records and to make velocity records jittery conversely the amplitude damping times of these resonances are much less than 1 s indicating that the time domain decay of the acceleration signal over 8 s is an incident wave effect overall the raw seismograms represent incident incoming high frequency 5 40 hz signals but poorly resolved directional effects preclude straightforward determination of the incident body waves

petrology of selected carbonaceous limestones and shales in late carboniferous coal basins of atlantic canada carbonaceous limestones and shales are associated with coal in late carboniferous alluvial to coastal successions of nova scotia the units are thin 45 km they consist of micrite and or illitic and kaolinitic clay and some contain abundant bivalves ostracodes pyrite up to 11 vol and phosphatic and sideritic nodules trace fossils are scarce to absent the organic material 2 43 toc is characterised as type ii iii and is mainly of terrestrial derivation predominantly vitrinite and sporinite with lamalginite and telalginite as minor constituents vitrinite reflectance measurements indicate immaturity ro 0 5 but are lower than those of associated coals source rock and hydrocarbon recovery potentials are good to very good and the potentials of some units compare favourably with those of alginite rich carboniferous oil shales in adjacent basins the carbonaceous units were deposited in shallow lakes and or interdistributary bays with aerobic to anaerobic bottom waters at times of minimal detrial input

the relationship between euramerican and cathaysian tropical floras in the late palaeozoic palaeobiogeographical and palaeogeographical implications abstract wetland plant communities persisted though much of the pennsylvanian in euramerica and are the dominant coal forming vegetation in this region distribution of these floras show a dramatic decline at the end of the carboniferous with many of the plant genera and species becoming extinct by the onset of the permian this has been correlated with climate change and in particular aridification associated with northwards plate motion and euramerica moving into the doldrums but is also associated with the variscan orogeny and forefront destroying large areas of formerly lowland basinal settings other factors may include pennsylvanian glaciations as evidenced by cyclothem and rhythmical deposition in lowlying wetland settings and change in eustatic base level evidence from euramerica demonstrates extinction of this kind of wetland biota by the earliest permian and the development of drier floras including conifer dominated assemblages however new data from other parts of the world most notably north china confirm this model and highlight the presence of similar coal swamps ranging from the late pennsylvanian through the permian in this paper we summarise and synthesize recent taxonomic and systematic investigations undertaken on the plant fossils from the pennsylvanian benxi formation the oldest recognised wetland plant community in china and the early permian taiyuan formation the best preserved wetland plant community from china results indicate a remarkable similarity of the pennsylvanian early permian floras of north china with the older assemblages in the pennsylvanian of euramerica and the presence of typical euramerican coal swamp plant families genera and in some cases species in china conclusions include the presence of the ameriosinian phytogeographical realm uniting euramerica and northern cathaysia at this time coal swamps in the permian of north china evolving from a euramerican origin and the dramatic floral turnover at the end of the carboniferous representing a regional event rather than a global extinction episode patterns of plant distribution through this interval have profound implications on established palaeogeographical models and support continental connection between euramerica and cathaysia before the end of the carboniferous contradicting ideas of cathaysian island biogeography and biotic distinction continental connection appears to be related to glacial eustatic low stand and previously shallow marine environments becoming vegetated also important is the fact that in both euramerica and north china the pattern of floristic demise within wetland plant communities are similar to each other implying the same causal mechanisms with plants occupying waterlogged positions being the most severely devastated however ecosystem demise occurred at the end of the carboniferous in euramerica and in the middle permian in north china but in both cases the primary cause was climate change

a preliminary study on the near source strong motion characteristics of the great 2008 wenchuan earthquake in china abstract the great 2008 wenchuan earthquake 12 may 2008 with a moment magnitude of 7 9 and a surface wave magnitude of 8 0 in shichuan china caused unprecedented loss of human life and widespread severe damage to many types of structures thirty two strong motion records were obtained within a source distance of 300 km and three near source records were obtained within a source distance of 20 km we present the preliminary results on the characteristics of the near source records and the strong motion aspects of this great earthquake this earthquake may be divided into four subevents according to the rupture time history and the final slip distribution three of the four subevents have large surface fault displacement and we consider the subevents that generated the three near source records as surface rupture earthquakes supported by the comparisons made to records from other surface rupture or buried fault earthquakes one station recorded strong ground motions from two subevents in two well separated time windows and this allows us to examine the effect of earthquake parameters for each of the subevents we find that in the spectral period range of 0 5 2 s the response spectra of the near source records from the wenchuan earthquake are significantly less than those of buried fault earthquakes such as the 1989 loma prieta earthquake and the 1994 northridge earthquake that have a much smaller moment magnitude than the wenchuan earthquake in the fault normal direction the displacement spectra at long period for the closest station are similar to those of the lucerne record from the 1992 landers earthquake but significantly smaller than those of the tcu052 and tcu068 records from the 1999 chi chi taiwan earthquake at short and intermediate period the near source spectra are much larger than the design spectra in the previous version of the chinese design code for the heavily damaged area but they are comparable at long spectral periods

peak accelerations from the 1992 landers and big bear california earthquakes peak ground accelerations pga at 181 sites for the landers mw 7 3 earthquake and at 85 sites for the big bear mw 6 2 aftershock are compared to the joyner and boore 1988 jb attenuation relationships and examined for spatial variations this study finds the following five results first at the 95 confidence level the mean of pga values for both earthquakes is significantly higher than the jb median by a factor near 2 second for distances greater than 70 km the observations from the landers earthquake indicate that attenuation of ground motion with distance is less than that predicted by geometric spreading and by jb third the northward propagation of the landers rupture significantly reduces pga values recorded at strong motion stations south of the epicenter fourth stations in the los angeles basin and the coachella valley recorded higher pga values than expected during both events finally site geology using the site classification scheme of jb generally does not have a statistically significant effect on pga except in the distance range from 60 to 100 km for the landers earthquake the observed difference between soil and rock site pga s between 60 and 100 km for the landers data set may be a combination of higher values of pga recorded at soil sites in basins an s wave radiation maximum in the san bernardino area and directivity effects

pedostratigraphy of chinese loess deposits and climatic cycles in the last 2 5 myr summary the pedostratigraphy and magnetostratigraphy of several sections in the loess plateau of north central china have been investigated and correlated the most complete and distinct loess paleosol sequence occurs in the baoji section of the southern part of the plateau thirty seven pedostratigraphic units are identifiable in the baoji section and correlated with those in other parts of the plateau the sequence represents thirty seven major cold to warm climatic cycles in the last 2 5 myr at about the time of the matuyama gauss magnetic reversal an abrupt climatic event occurred in north china represented by the shift of the well weathered red clay formation below the m g boundary to the alternating loess and paleosol units above marking the beginning of a new epoch in the course of climatic evolution in addition there are two other major shifts of dominant periods of climatic cycles recorded in the loess paleosol sequences one occurring at about 1 5 myr and another at about 0 8 myr the pedostratigraphy of loess deposits in north central china provides an independent measure of the world wide climatic fluctuations and is now the most complete and reliable record of the major climatic cycles in the last 2 5 myr

late cenozoic eolian deposition in the north pacific asian drying tibetan uplift and cooling of the northern hemisphere a newly constructed record of eolian dust accumulation from the central north pacific shows that dust deposition increased by an order of magnitude quite rapidly at 3 6 ma we associate this sudden drying with the uplift of at least the northern portion of the tibetan plateau shutting off the indian ocean moisture source to central and western china this ten fold increase in atmospheric dust loading appears to be associated with the 1 m y long shift toward heavy 18o values that occurred at 3 6 2 6 ma the dust grain size record of wind intensity begins its late cenozoic coarsening a million years before the drying event at 4 5 ma the northern hemisphere cooling that results in intensification of the subpolar westerly winds may have as its ultimate cause the drawdown of atmospheric co2 in the latest miocene and the early pliocene closing of the panamanian seaway

directional site resonances and the influence of near surface geology on ground motion the authors examine the horizontal motions at close stations from earthquakes in the loma prieta and whittier narrows sequences to study the shear wave polarizations they use a dense six station array recording 10 aftershocks for the former and use two events and 11 stations across the los angeles area for the latter they compute the average azimuth of strongest shaking in the shear wave as a function of frequency from 1 to 18 hz for each record of each earthquake the direction of shaking at a given frequency often correlates much better with an empirical site resonance direction than with the direction of shaking expected from the focal mechanism of the earthquake the effect tends to be greatest at the frequencies that are the most amplified this phenomenon can complicate determination of the earthquake source at frequencies higher than 1 hz further since sites only 25 meters apart show different preferred directions very near surface geology is probably responsible estimation of directional site resonances may prove useful for seismic design

estimates of the ground accelerations at point reyes station during the 1906 san francisco earthquake we have developed an analytical solution for the rocking and overturning response of a two dimensional symmetric rigid block subject to a full sine wave of horizontal ground acceleration we use this solution to provide lower bound estimates of the peak ground acceleration at point reyes station california during the 1906 san francisco earthquake that toppled the san francisco bound train our results for a 3 damping ratio indicate that for a single cycle of a sine wave the minimum toppling accelerations at 1 1 5 and 2 hz are 0 35g 0 5g and 1 05g respectively for more realistic accelerograms the toppling accelerations are about 1 1g complex synthetic and 0 76g lucerne record of the 1992 landers earthquake

magnetostratigraphy and paleoclimatic interpretation of a continuous 7 2 ma late cenozoic eolian sediments from the chinese loess plateau an almost 300m thick eolian sequence of late cenozoic sediments which includes 162 5m of quaternary loess paleosols and 126m of late tertiary eolian red clay from the central part of the chinese loess plateau was investigated to determine the magnetostratigraphy the results show that eolian dust accumulation and by inference the related east asia paleomonsoon had begun by 7 2ma as paleomonsoon are largely controlled by the tibetan plateau this implies that the plateau had reached some critical elevation by 7 2ma the section also documents a rapid increase in eolian dust accumulation in the late cenozoic at 3 2ma that is probably due to the influence of global ice volume on the east asian monsoon

magnetostratigraphy of the baoji loess paleosol section in the north central china loess plateau the baoji section is judged to be the most complete accessible quaternary loess paleosol section in the north central china loess plateau it is located 5 km north of the city of baoji it contains 37 paleosols and was recently named the type pedostratigraphic section the pedostratigraphic units geosols of the baoji section can be correlated throughout the loess plateau by a combination of magnetostratigraphy and character position and association of pedostratigraphic units magnetic properties were determined from 483 samples taken from 159 m of loess that overlies the red clay formation all major reversals that occurred in the last 2 5 ma were recorded the brunhes matuyama boundary occurs at a depth of 58 5 m within loess unit l8 the jaramillo subchron between 72 0 m in loess unit l10 and 76 4 m in paleosol s11 the olduvai subchron between 125 5 m in loess unit l25 and 131 5 m in loess unit l27 and the gauss matuyama boundary at 157 8 m within loess unit l33 just above the contact with the red clay formation this is the only known site where all major magnetic reversals are clearly defined in distinct field identifiable loess soil units in one section the magnetostratigraphy of the baoji section is thus recommended as the type section for the loess plateau

spatial and temporal distribution of slip for the 1992 landers california earthquake we have determined a source rupture model for the 1992 landers earthquake m w 7 2 compatible with multiple data sets spanning a frequency range from zero to 0 5 hz geodetic survey displacements near field and regional strong motions broadband teleseismic waveforms and surface offset measurements have been used explicitly to constrain both the spatial and temporal slip variations along the model fault surface our fault parameterization involves a variable slip multiple segment finite fault model which treats the diverse data sets in a self consistent manner allowing them to be inverted both independently and in unison the high quality data available for the landers earthquake provide an unprecedented opportunity for direct comparison of rupture models determined from independent data sets that sample both a wide frequency range and a diverse spatial station orientation with respect to the earthquake slip and radiation pattern in all models consistent features include the following 1 similar overall dislocation patterns and amplitudes with seismic moments of 7 to 8 10 26 dyne cm seismic potency of 2 3 to 2 7 km 3 2 very heterogeneous unilateral strike slip distributed over a fault length of 65 km and over a width of at least 15 km though slip is limited to shallower regions in some areas 3 a total rupture duration of 24 sec and an average rupture velocity of 2 7 km sec and 4 substantial variations of slip with depth relative to measured surface offsets the extended rupture length and duration of the landers earthquake also allowed imaging of the propagating rupture front with better resolution than for those of prior shorter duration strike slip events our imaging allows visualization of the rupture evolution including local differences in slip durations and variations in rupture velocity rupture velocity decreases markedly at shallow depths as well as near regions of slip transfer from one fault segment to the next as rupture propagates northwestward along the multiply segmented fault length the rupture front slows as it reaches the northern limit of the johnson valley landers faults where slip is transferred to the southern homestead valley fault an abrupt acceleration is apparent following the transfer this process is repeated and is more pronounced as slip is again passed from the northern homestead valley fault to the emerson fault although the largest surface offsets were observed at the northern end of the rupture our modeling indicates that substantial rupture was also relatively shallow less than 10 km in this region

mild displacements of boulders during the 2019 ridgecrest earthquakes strong seismic waves from the july 2019 ridgecrest california earthquakes displaced rocks in proximity to the m 7 1 mainshock fault trace at several locations in this report we document large boulders that were displaced at the wagon wheel staging area wwsa approximately 4 5 km southeast of the southern terminus of the large m 6 4 foreshock rupture hereafter the large foreshock and 9 km southwest of the nearest approach of the m 7 1 mainshock surface rupture some boulders appear to have slid along essentially flat surfaces which suggest that dynamic stresses overcame the coefficient of friction other boulders appear to have rocked within their sockets in both cases we use simple mechanical models to estimate total peak dynamic accelerations between 0 5 and 1g commensurate with modified mercalli intensity 9 it is unclear if the strongest shaking at this location occurred during the large foreshock or the m 7 1 mainshock the inferred accelerations are higher than predicted mainshock ground motions at wwsa although local high accelerations could have been generated by path site or source effects gaps between boulders and their sockets are easily visible in the immediate aftermath of earthquakes and provide a quick indication of strong shaking more importantly the gaps quickly fill with surficial organic debris including seeds and leaves of the year that quickly become entombed boulders may thus potentially be extracted to examine gap fillings associated with past earthquakes providing a new datable paleoseismic method

the westphalian d fossil lepidodendrid forest at table head sydney basin nova scotia sedimentology paleoecology and floral response to changing edaphic conditions copyright c 1996 elsevier science b v all rights reserved strata of westphalian d age on the western coast of the sydney basin expose a fossil forest of approximately 30 lepidodendrid trees within one of several clastic splits of the harbour seam a mutidisciplinary approach was employed to interpret the origins of the coal bed the depositional history of the site and the response of the fossil forest to changing edaphic conditions the megaspore and miospore records indicate that the mire vegetation was dominated by arboreous lycopsids especially paralycopodites with subdominant tree ferns petrographic palynological and geochemical evidence suggest that the harbour coal bed at table head originated as a rheotrophic cf planarr mire eutric histosolr the mire forest is interpreted to have been engulfed by prograding distributary channel sediments sparse protist assemblages are suggestive of a freshwater delta plain lake environment occasionally in contact with brackish waters lepidodendrids persisted as site colonizers of clastic substrates even after burial of the rheotrophic peatland and influenced the morphology of deposited sediment but apparently were unable to colonize distributary channels equivocal taxonomic data compression fossilsr show the fossil forest to have been composed of both monocarpic lepidodendronr and polycarpic diaphorodendron paralycopodites sigillariar lycopsids genera recorded in the palynology of the uppermost ply of the underlying coal bed comparatively rare within the clastic beds of the fossil forest however is the stem compression of paralycopodites whose dispersed megapores and miospores dominate the underlying coal bed tree diameter data recorded equivalent to breast height indicate a forest of mixed age these data would appear to suggest that some lepidodendrids employing a polycarpic reproductive strategy were better able to cross the ecological barrier imposed between peat and clastic substrates foliar compressions indicate that an understory or stand of psaronius type tree ferns co existed with the lepidodendrids on clastic substrates which developed as incipient gleysol soils the entombment of the forest can be ascribed to its distributary coastal setting local subsidence and a seasonal climate that fostered wildfire and increased sedimentation

mineral magnetic record of the chinese loess and paleosols variations in the magnetic susceptiblity of the chinese loess and its interbedded paleosols correlate strikingly well with the deep sea oxygen isotope record low susceptibility values are found for the loess layers and high values are found for the soil horizons two interpretative models have been advanced to account for these magnetic variations both of these models discount any significant in situ formation of magnetite during soil forming periods instead they infer relative concentration of detrital or atmospheric magnetite at these times we critically examine the assumptions made in these models and on the basis of some new mineral magnetic data and fromalized magnetic flux calculations offer an alternative explanation of the loess magnetic record our model identifies pedogenic formation of magnetite as the major contributor to the high magnetic susceptibility of the paleosols the formation and preservation of this pedogenic magnetite is dependent on soil froming conditions and hence reflects the regional climate

temporal and spatial distribution of ostracodes across the pennsylvanian permian boundary interval in eastern north america abstract ostracodes recovered from eastern north american coal measures in the appalachian illinois and maritimes basins have the potential to resolve the temporal and spatial relationships of the strata deposited during the pennsylvanian permian boundary interval the ostracode associations include 1 a pennsylvanian virgilian gzhelian marine association dominated hollinella cushmani with abundant brachiopods and foraminifera exclusive to the gil 30 core in kentucky illinois basin 2 a latest pennsylvanian virgilian gzhelian brackish association dominated by geisina upsoni kellet cavellina nebrascensis geintz and velatomorpha fittsi kellet exclusive to the gil 30 core in kentucky illinois basin and 3 an uppermost permian asselian sakmarian association of nonmarine taxa dominated by whipplella cuneiformis holland whipplella parvula holland paleodarwinula hollandi scott and haworthina bulleta harris and lalicker that occurs in the uppermost continental facies of both the illinois and dunkard basins a comparable nonmarine association of paleodarwinula hollandi and whipplella bretonensis copeland occurs in the bolsovian to cantabrian moscovian to kasimovian coal measures of the maritimes basin of atlantic canada the data presented herein provides new information about the withdrawal of marine waters from several major late paleozoic basins in eastern north america mid continental marine influence persisted into the latest pennsylvanian to earliest permian during deposition in the eastern illinois basin on the western appalachian coastal plain the uppermost nonmarine association of nonmarine ostracoda in both the illinois basin and dunkard basin indicates a synchronous development of aquatic freshwater faunas during lower permian times with increasing geographic isolation of the eastern north american basins the dispersal and radiation of ostracoda in these basins was apparently facilitated by brood rearing as demonstrated by the dominance of the platycopina and darwinulocopina

compression cuticle relationship of seed ferns insights from liquid solid states ftir late palaeozoic early mesozoic canada spain argentina abstract cuticles have been macerated from suitably preserved compressed fossil foliage by schulze s process for the past 150 years whereas the physical biochemical relationship between the coalified layer with preserved cuticle as a unit has hardly been investigated although they provide complementary information this relationship is conceptualized by an analogue model of the anatomy of an extant leaf vitrinite mesophyll cuticle biomacropolymer compression alkaline solutions from schulze s process as a proxy for the vitrinite are studied by means of liquid solid states fourier transform infrared spectroscopy ftir in addition cuticle free coalified layers and fossilized cuticles of seed ferns mainly from canada spain and argentina of late pennsylvanian late triassic age are included in the study sample infrared data of cuticle and alkaline solutions differ which is primarily contingent on the mesophyll biomacropolymer characteristics the compression records two pathways of organic matter transformation one is the vitrinized component that reflects the diagenetic post diagenetic coalification history parallel with the evolution of the associated coal seam the other is the cuticle that reflects the sum total of evolutionary pathway of the biomacropolymer its monomeric or polymeric fragmentation though factors promoting preservation include entombing clay minerals and lower ph conditions caution is advised when interpreting liquid state based ftir data as some ir signals may have resulted from the interaction of schulze s process with the cuticular biochemistry a biochemical study course for taphonomy is suggested as fossilized cuticles cuticle free coalified layers and compressions are responses to shared physicogeochemical factors

phyto and chronostratigraphical correlations between the late pennsylvanian morien group sydney nova scotia and the silesian pennant measures south wales three macrofloral interval zones lobatopteris vestita l micromiltoni and linopteris bunburii recognized in the westphalian d and the cantabrica biozone in the stephanian of europe are also present in the morien group pictou group of sydney coalfield nova scotia these zones allow a more refined correlation to be made between sequences of the same age in the sydney and south wales coalfields and thus between western europe and north america in general

complex trichomes associated with foliar odontopteris schlotheimii brongniart manebach type locality germany implication for taxonomy abstract reported for the first time is a physical association of complex structured trichomes with foliar odontopteris schlotheimii brongniart 1831 from the type manebach formation germany this is based on examining rock matrices dissolved by hydrofluoric acid of bipinnate and pinnate material these trichomes and their inferred dense distribution most significantly are directly comparable with those of specimens of odontopteris cantabrica wagner 1969 from the canadian sydney coalfield used as index fossil to establish the cantabrian substage this result is one strong argument that invites comparison with o schlotheimii in addition to the acknowledged common pinnule morphologies of o cantabrica and o schlotheimii additionally trichomes are not observed in samples of the rock matrix of a fragmentary axis associated with lesquereux specimen of o schlotheimii southern anthracite field eastern pennsylvania usa results of the trichomic comparison and taxonomic implication thereof will be discussed in a future paper

the onset of extensive loess deposition around the g m boundary in china and its palaeoclimatic implications abstract in northern china the red clay loess contact is palaeomagnetically defined at about the gauss matuyama boundary the red clay formation has recently been proposed as mostly of wind blown origin and can be interpreted as having been formed under climatic conditions of continuous warmth punctuated by small amplitude oscillations the shift from red clay development to extensive loess deposition exhibits a 3 fold abrupt increase in aeolian dust deposition rate and marks the beginning of frequent and chaotic climatic fluctuations this event implies a large scale reorganization of the atmospheric circulation over east asia in particular the northward shift and intensification of the siberian high which may have resulted from a dramatic uplift of the tibetan plateau compared to another climatic shift recorded by the chinese loess deposits which occurred at about the upper boundary of the olduvai subchron the red clay loess shift is much more pronounced and recognizable in the field it appears that in regional stratigraphic studies the g m magnetic reversal has a better correlation potential than the upper olduvai

preliminary magnetostratigraphy of the red clay underlying the loess sequence at baoji china magnetic remanence and bulk susceptibility measurements are reported from 93 samples spanning the uppermost 27m of the red clay underlying the loess sequence at baoji shaanxi province china if a new previously undetected short about 20ka excursion or reversed interval near 3 3ma be accepted then a reasonable fit to the standard time scale emerges a linear accumulation rate of 1 5cm ka is implied and the correlation coefficient is 0 992 no significant hiatus occurs between the red clay and the overlying loess so the 27m investigated reach back to about 4 3ma fourier analysis of the bulk susceptibility data yields a strong peak near 400ka in agreement with astronomical calculations of the orbital parameters responsible for climatic forcing

the westphalian stephanian macrofloral record from the south wales coalfield uk the south wales coalfield has the most complete westphalian macrofloral record anywhere on the variscan foreland or adjacent basins with 135 biodiversity meaningful morphospecies having been recognized all of the standard macrofloral biozones of the westphalian stage have been recognized although a detailed comparison with the central pennines coalfields has indicated some discrepancies in the relative positions of the biozonal boundaries total species richness progressively increases through the langsettian substage and then remains relatively stable through most of the duckmantian and bolsovian substages there is a distinct reduction in total species richness towards the top of the bolsovian substage but this partially recovers in the middle asturian substage with the appearance of a range of marattialean ferns and medullosalean and callistophytaleans pteridosperms there is no evidence of any significant drop in total species richness towards the top of the succession indicating that conditions at this time were relatively stable the change from coastal floodplain to alluvial braidplain conditions in middle bolsovian times correlates with a marked increase in the proportion of medullosalean remains being preserved in the adpression record reflecting an expansion of the clastic substrate habitats