morphology and mechanics of submarine spreading a case study from the storegga slide spreading is a common type of ground failure in subaerial environments however this type of mass movement has hardly been documented in submarine settings in this paper we show that spreading covers at least 25 of the storegga slide scar area a giant submarine slide located offshore mid norway the morphological signature of spreading is a repetitive pattern of ridges and troughs oriented perpendicular to the direction of movement two modes of failure can be identified retrogressive failure of the headwall and slab failure and extension both involving the breakup of a sediment unit into coherent blocks these blocks are displaced downslope along planar slip surfaces limit equilibrium modeling indicates that loss of support and seismic loading are the main potential triggering mechanisms the extent of displacement of the spreading sediment is controlled by gravitationally induced stress angle of internal friction of the sediment pore pressure escape and friction the resulting block movement pattern entails an exponential increase of displacement and thinning of the failing sediment with distance downslope sediment properties explain the remaining spatial variation of ridge and trough morphologies associated with spreading

the evolution of el nino past and future abstract we review forecasts of the future of el nino and the southern oscillation enso a coupled instability of the ocean atmosphere system in the tropical pacific with global impacts enso in the modern world is briefly described and the physics of the enso cycle is discussed particular attention is given to the bjerknes feedback the instability mechanism which figures prominently in enso past and future our knowledge of enso in the paleoclimate record has expanded rapidly within the last 5 yr the enso cycle is present in all relevant records going back 130 kyr it was systematically weaker during the early and middle holocene and model studies indicate that this results from reduced amplification in the late summer and early fall a consequence of the altered mean climate in response to boreal summer perihelion data from corals shows substantial decadal and longer variations in the strength of the enso cycle within the past 1000 yr it is suggested that this may be due to solar and volcanic variations in solar insolation amplified by the bjerknes feedback there is some evidence that this feedback has operated in the 20th century and some model results indicate that it will hold sway in the greenhouse future but it is very far from conclusive the comprehensive general circulation models used for future climate projections leave us with an indeterminate picture of enso s future some predict more enso activity some less with the highly uncertain consensus forecast indicating little change

accumulation of organic rich sediments in a dendritic fluvial lacustrine mire system at tasik bera malaysia implications for coal formation abstract the tasik bera mire system represents deposition of peat and peaty sediments within a dendritic fluvial drainage basin in the humid tropics as such it serves as an analogue for the earliest stages of coal deposition in low relief topogenous coal swamps peaty sediments have been accumulating for at least 4500 years in the lowest part of the basin but accumulation rates and hence the thickness and lateral extent of the mire underwent a rapid increase and expansion beginning at about 660 years b p the sediments are highly variable both vertically and laterally the variations principally controlled by the type of vegetation dominant vegetation in turn is related to the degree of wetness of the site three distinct environments of deposition contribute peat with physical characteristics which can be related to coals the limnetic environment dominated by algae and easily degraded aquatic macrophytes contributes very fine hemic peaty sediment with high fine silt content and a large algal component the littoral environment is dominated by sedges and the woody shrub pandanus both of which have a large subaqueous biomass and are quite resistant to degradation sediment from this environment is woody hemic to coarse hemic with a moderate to high very fine silt content and a much smaller algal element forest swamps which occupy most of the mire area contribute woody fibric to hemic peaty sediments with low to moderate mineral matter content in the form of clays and very fine silt succession from both limnetic to forest swamp and the reverse is recorded in cores from different sites in coals these transitions would be manifest as both brightening upward algaedominated peat to woody peat and dulling upward the reverse sequence trends the first in the topographically lower part of the basin the second in the middle reaches no part of the mire yet studied is approaching oligotrophic conditions allowing for a compression ratio of 5 1 thin stony coals from the tasik bera mire would be laterally discontinuous and would vary from about 1 m in thickness at channel margins tapering out to nothing as they onlap the interfluves

activity along the osning thrust in central europe during the lateglacial ice sheet and lithosphere interactions abstract the osning thrust is one of the major fault systems in central europe with a length of approximately 115 km it underwent a polyphase tectonic evolution in the mesozoic that ranged from extensional movements in the jurassic to reverse faulting and thrusting during inversion in the late cretaceous a series of complex metre scale faults and related fold structures are developed within the upper pleistocene alluvial aeolian complex of the upper senne 1 km away from the thrust the faults dip towards the north and show offsets in a range of several decimetres growth strata indicate a two fold evolution of the structures the faults began as normal faults and were later transformed into reverse faults which resulted in the formation of small scale inversion structures with a typical harpoon shape glaciotectonics can be ruled out as the driving mechanism for these structures because new optically stimulated luminescence osl ages imply that the sedimentary succession was deposited during the late pleistocene between 29 3 2 9 ka and 13 1 1 5 ka at which time the ice margin was much further to the northeast we believe the inversion structures were caused by movement on the osning thrust due to generation of a forebulge of the late pleistocene weichselian ice sheet this led to normal faulting as a consequence of extension in the forebulge area during glaciation the osl ages for the normal fault related growth strata are in a range of 16 13 ka later reverse movements occurred during deglaciation due to the n s directed compressional stress field in northern germany numerical simulations of the deglaciation seismicity point to seismic events with a thrust mechanism in the study area between 15 5 and 12 3 ka bp although normal faulting is also possible in this time period numerous soft sediment deformation structures imply that movement on the osning thrust caused earthquakes with a significant magnitude in the autumn of 1612 an earthquake took place in this area it is very likely that this event is related to background seismicity on this fault although movement due to the influence of the ongoing glacial rebound in fennoscandia is also possible

soil conditions and slope stability in the ormen lange area abstract the ormen lange gas field is located in 850 1100 m water depth in the slide scar of the enormous storegga slide this slide occurred about 8200 years ago and left steep and high scarps above and below the planned field development area today s stability of these scarps has been a major concern for the field development work this paper gives an overview of soil investigations evaluation of potential trigger mechanisms and stability analyses performed to demonstrate adequate conditions the area under consideration is large with a limited number of geotechnical borings and integration of geological geophysical and geotechnical information was required to develop a geotechnical model of the area the stress history and the soil conditions are strongly influenced by rapid deposition during glacial periods by the loss of overburden from the storegga slide and glacial loading along the shelf edge natural and project induced triggering sources with potential for generation of renewed slide activity were evaluated with respect to magnitude and location and possible influence area relative to the major scarps stability analyses were carried out for critical sections of the scarps under gravity loading and under combination of gravity and potential triggering sources applying drained analyses for long term gravity loading and undrained analyses considering gravity combined with short term load effects project induced load effects like weight of equipment and rockfills anchor loads and effects of drilling and production activities were found to have insignificant effect on the large scale stability of the headwalls and local surficial slope failure can be handled by adequate engineering and lay out with respect to natural triggering sources it was concluded that an extremely strong earthquake with a very low probability of occurrence is the only realistic mechanism for triggering of new slides in the ormen lange area

a comparison of strain rates and seismicity for fennoscandia depth dependency of deformation from glacial isostatic adjustment summary we investigate the influence of the glacial isostatic adjustment gia on the deformation at the surface and at seismogenic depths in fennoscandia the surface strain rate field derived from geodetic data is controlled by gia which causes nw se extension of up to 4 10 9 yr 1 in most of mainland fennoscandia surrounded by regions of radial shortening towards the centre of uplift the seismic deformation field derived from a new compilation of focal mechanisms shows consistent nw se compression on the norwegian continental margin and a tendency towards tension in mainland fennoscandia the seismic moment rate is at least two orders of magnitude smaller than the geodetic moment rate we propose that the low level of seismicity and the tendency towards tensional focal mechanisms in mainland fennoscandia may be explained by the destructive interference of the regional stress from ridge push with the flexural stress due to gia

postglacial seismicity offshore mid norway with emphasis on spatio temporal magnitudal variations abstract norway and its continental margin in spite of being located in an intraplate environment is of great interest from a neotectonic perspective influence on neotectonics stems both from the fact that this is a recently deglaciated region in which significant rebound is still occurring and from its proximity both to a rifted continental margin and to failed rift zones passive continental margins and rift related structures are the most seismically active ones within stable continental regions with a number of well documented earthquakes of magnitude 7 and higher as observed around the globe indeed the disparity in seismicity between such regions and plate boundary regions is greater in terms of return times than in terms of maximum magnitude a recent detailed assessment of neotectonics in fennoscandia has shown strong bedrock related evidence for several large magnitude m 7 earthquakes in the northern areas lapland while few if any similar observations have been made farther south a possible explanation for this is that postglacial earthquakes have been occurring on hidden thrusts in the south in fact several major structures have recently been mapped and shown to have capabilities to accommodate m 6 5 7 earthquakes without breaking the surface given that the largest historically known earthquake in fennoscandia is only of the order of m 5 8 it is likely therefore that the potentially largest magnitude in this region may be well above this

the stratigraphy and fire history of the kutai peatlands kalimantan indonesia abstract the equatorial peatlands of the kutai lowland of eastern kalimantan are generally 4 10 m in thickness but some sections exceed 16 m in depth the deposition of peat commenced about 8000 yrs ago after shallow flooding of the basin by the mahakam river the earliest vegetation is a pandanus swamp which grades upwards to swamp forest dominated by dipterocarps the peatland has expanded laterally and rivers have maintained narrow levee channel tracks through the swamp which has grown vertically in balance with river accretion historical fires are associated with extreme el nino years of drought but human agency is important the fires of 1982 1983 and 1997 1998 burnt up to 85 of the vegetation on the peatland although charcoal analyses show that fire has occurred throughout the history of the peatland it is rare in forests remote from rivers until the last 3000 years and only common within the last millennium fires are earlier and more frequent in sites accessible from waterways and floodplains have been widely burnt down to water table or below forming extensive lakes

late cretaceous to recent tectonic evolution of the north german basin and the transition zone to the baltic shield southwest baltic sea abstract in this study we investigate the late cretaceous to recent tectonic evolution of the southwestern baltic sea based on a dense grid of seismic reflection profiles this area covers the baltic sea sector of the salt influenced north german basin and its transition to the salt free baltic shield across the tornquist zone the upper cretaceous to recent structural evolution is discussed by means of individual seismic sections and derived high resolution time structure maps of the main horizons i e the upper cretaceous tertiary and pleistocene the upper cretaceous and tertiary layers reveal numerous significant faults throughout the study area several of these faults propagate upwards across the unconsolidated pleistocene sediments and occasionally penetrate the surface the salt influenced north german basin reveals three major fault trends nw se n s and nne ssw several of these faults are located directly above basement sub salt faults and salt pillows the majority of these faults are trending n s to nne ssw and parallel the direction of the gluckstadt graben faults in the salt free tornquist zone we identify two major shallow fault trends which are nw se and ne sw the majority of these faults are located above basement faults following the direction of the tornquist zone we conclude that generally basement tectonics controls activation and trends of shallow faults if salt is present the ductile salt layer causes a lateral shift between the sub and supra salt faults major plate reorganisation related to the africa iberia europe convergence and the subsequent alpine orogeny caused reactivation of pre existing faults and vertical salt movement in the late cretaceous the change of stress orientation from ne sw to a nw se during neogene caused another phase of fault and salt tectonic reactivation we explain that the ice sheet loading and or present day stress field may have acted in combination causing the recent tectonics and upward extension of the faults

characterization and quantification of inorganic constituents of tropical peats and organic rich deposits from tasek bera peninsular malaysia implications for coals abstract since the carboniferous tropical latitudes have been the site of formation of many economic coal deposits most of which have a restricted range of mineralogical composition as a result of their depositional environment climatic conditions and diagenesis mineralogical and microscopic investigations of tropical peats from tasek bera peninsular malaysia were performed in order to better understand some of these factors controlling the nature distribution and association of inorganic matter in peat forming environments distribution and nature of the inorganic fraction of peat deposits give insight into the weathering conditions and detrital input into the mire system because the inorganic composition of peat deposits is determined by plant communities height of water table and climate the results of the quantitative and qualitative analysis can be used to reconstruct palaeoclimatic conditions tasek bera is a peat accumulating basin in humid tropical malaysia with organic deposits of low to high ash yield and thus representative of many ancient peat forming environments clay minerals dominate the mineralogical composition of the peat and organic rich sediments while quartz and clays dominate the underlying siliciclastic deposits kaolinite is the most abundant clay mineral in the organic deposits with minor amounts of illite and vermiculite particle size analyses indicate that 50 of the inorganic detrital fraction is 75 of the ash constituents as a consequence the vegetational communities make an important contribution to the inorganic and overall ash composition of peats and coals the ash content of the often inundated peat consists on average of 10 opaline silica from diatoms and sponge spicules while the ash of the top deposits may have up to 50 biogenic silica hence al and si hydroxides and the opaline silica from diatoms and sponges represent a large repository of al and si which may form the basis of mineral transformation neoformation and alteration processes during coalification of the peat deposits as a result most coal deposits from paleotropical environments are anticipated to have little to no biogenic inorganic material but high amounts of secondary clays such as kaolinite detrital kaolinite resilisified kaolinite or desilisified gibbsite or illite and various amounts of detrital and authigenetic quartz

a hybrid method for the estimation of ground motion in sedimentary basins quantitative modeling for mexico city to estimate the ground motion in two dimensional 2d laterally heterogeneous anelastic media a hybrid technique has been developed that combines modal summation and the finite difference method in the calculation of the local wave field owing to a seismic event both for small and large epicentral distances it is possible to take into account the source path and local soil effects as a practical application we have simulated the ground motion in mexico city caused by the michoacan earthquake of september 19 1985 by studying the one dimensional 1d response of the two sedimentary layers present in mexico city it is possible to explain the difference in amplitudes observed between records for receivers inside and outside the lake bed zone these simple models show that the sedimentary cover produces the concentration of high frequency waves 0 2 to 0 5 hz on the horizontal components of motion the large amplitude coda of ground motion observed inside the lake bed zone and the spectral ratios between signals observed inside and outside the lake bed zone can only be explained by 2d models of the sedimentary basin in such models the ground motion is mainly controlled by the response of the uppermost clay layer the synthetic signals explain the major characteristics relative amplitudes spectral ratios and frequency content of the observed ground motion the large amplitude coda of the ground motion observed in the lake bed zone can be explained as resonance effects and the excitation of local surface waves in the laterally heterogeneous clay layer also for the 1985 michoacan event the energy contributions of the three subevents are important to explain the observed durations

a record of late pleistocene and holocene carbon accumulation and climate change from an equatorial peat bog kalimantan indonesia implications for past present and future carbon dynamics a 9 5 m core from an inland peatland in kalimantan indonesia reveals organic matter accumulation started around 26 000 cal yr bp providing the oldest reported initiation date for lowland ombrotrophic peat formation in se asia the core shows clear evidence for differential rates of peat formation and carbon storage a short period of initial accumulation is followed by a slow rate during the lgm with fastest accumulation during the holocene between 13 000 and 8000 cal yr bp 450 cm of peat were deposited with highest rates of peat 2 mm yr 1 and carbon 90 g c m 2 yr 1 accumulation between 9530 and 8590 cal yr bp these data suggest that kalimantan peatlands acted as a large sink of atmospheric co2 at this time slower rates of peat 0 15 0 38 mm yr 1 and carbon 7 4 24 0 g c m 2 yr 1 accumulation between 8000 and 500 cal yr bp coincide with rapid peat formation in coastal locations elsewhere in se asia the average lorca long term apparent carbon accumulation rate for the 9 5 m core is 56 g c m 2 yr 1 these data suggest that studies of global carbon sources sinks and their dynamics need to include information on the past and present sizeable peat deposits of the tropics copyright 2004 john wiley sons ltd

seismotectonics of the norwegian continental margin the norwegian continental margin and surrounding areas are seismically less active than some other passive margins worldwide indicating a potential earthquake deficit the adjacent oceanic crust is mostly aseismic except for parts of the lofoten and norway basins which have experienced rapid deposition of glacial sediments the excess load has enhanced the local stress field and in turn the seismic activity the marginal highs along the continent ocean transition and the part of the more and voring basins which experienced crustal extension prior to the early tertiary breakup are practically aseismic this region is also underlain by high velocity lower crust emplaced during breakup suggesting crustal strengthening which also may increase the return periods for the largest events farther landward a spatial correlation of seismic activity and the glacial sediment wedge suggests a causal relationship expressed through preferential rejuvenation of late jurassic early cretaceous faults the locally high seismic activity in the coastal region occurs in areas where the continental crust is relatively thick 25 30 km but still thinner than in the shield area farther east 45 50 km although stress relations are complex we suggest that increased stress due to appreciable postglacial rebound gradients in the coastal region may be a contributing factor while the stress field along the margin complies in general with the ridge push force we infer that regional and local stress enhancement factors are not only present in this region but also necessary for explaining the earthquake activity the relative importance of local stress sources is supported by several cases of 90 stress rotations relative to the ridge push direction the superposition of regional and local stress together with the existence of weakness zones and faults yields potentials for earthquakes primarily through structural reactivation

forest dynamics and tip up pools drive pulses of high carbon accumulation rates in a tropical peat dome in borneo southeast asia singapore national research foundation singapore mit alliance for research and technology

mineralogy and geochemistry of archaean greenstone belt hosted mn formations and deposits of the dharwar craton redox potential of proto oceans

development and carbon sequestration of tropical peat domes in south east asia links to post glacial sea level changes and holocene climate variability abstract tropical peatlands of se asia represent a significant terrestrial carbon reservoir of an estimated 65 gt c in this paper we present a comprehensive data synthesis of radiocarbon dated peat profiles and 31 basal dates of ombrogenous peat domes from the lowlands of peninsular malaysia sumatra and borneo and integrate our peatland data with records of past sea level and climate change in the region based on their developmental features three peat dome regions were distinguished inland central kalimantan borneo kutai basin borneo and coastal areas across the entire region with the onset of the holocene the first peat domes developed in central kalimantan as a response to rapid post glacial sea level rise over the sunda shelf and intensification of the asian monsoon peat accumulation rates in central kalimantan strongly declined after 8500 cal bp in close relation to the lowering rate of the sea level rise and possibly influenced by the regional impact of the 8 2 ka event peat growth in central kalimantan apparently ceased during the late holocene in association with amplified el nino activity as exemplified by several truncated peat profiles peat domes from the kutai basin are all younger than 8300 cal bp peat formation and rates of peat accumulation were driven by accretion rates of the mahakam river and seemingly independent of climate most coastal peat domes the largest expanse of se asian peatlands initiated between 7000 and 4000 cal bp as a consequence of a holocene maximum in regional rainfall and the stabilisation and subsequent regression of the sea level these boundary conditions induced the highest rates of peat accumulation of coastal peat domes the late holocene sea level regression led to extensive new land availability that allowed for continued coastal peat dome formation until the present the time weighted mean holocene peat accumulation rate is 0 54 mm yr 1 for central kalimantan 1 89 mm yr 1 for kutai and 1 77 mm yr 1 for coastal domes of sumatra and borneo the mean holocene carbon sequestration rates amount to 31 3 g c m 2 yr 1 for central kalimantan and 77 0 g c m 2 yr 1 for coastal sites which makes coastal peat domes of south east asia the spatially most efficient terrestrial ecosystem in terms of long term carbon sequestration

holocene climate change in the western part of taihu lake region east china abstract the taihu lake basin is one of the most sensitive areas to climate change in the east asian summer monsoon easm influenced region there are significant differences regarding the interpretation of climate history for this area during the holocene due to a lack of high resolution paleoclimate records to better understand this scientific issue here we provide a new record of holocene climate change from the western part of taihu lake region east china a 4 m depth profile from gaochun has provided a 13 200 year record of climate change holocene climate change was reconstructed for the western part of taihu lake area based on various proxy records including pollen charcoal degree of humification doh and loss on ignition loi from the gaochun site the results indicate that climate during the late pleistocene 13 200 10 700 cal yr b p and early holocene 10 700 8000 cal yr b p was warm and humid alternated with several cold and dry intervals the late pleistocene and early holocene was a transitional period from cold dry to warm wet climates the middle holocene 8000 4400 cal yr b p was still warm and humid with a relatively stable climate the period between 8000 and 5300 cal yr b p was the holocene climate optimum hco during the late holocene 4400 0 cal yr b p the climate was cool but still humid in addition climate change at the western part of taihu lake during the late pleistocene and holocene was unstable containing several short term climate events such as younger dryas yd 8 2 ka and 4 2 ka events these abruptly occurred climate events were indicated by various paleoclimatic proxy indicators and can be compared with related records from other regions our findings suggest that the easm strength was strongest during the middle holocene between 8000 and 5300 cal yr b p which can be depicted as the period of hco

peat accumulating depositional systems of sarawak east malaysia many coal deposits originate in deltaic estuarine and coastal plain settings and a knowledge of interrelationships between the tectonic and depositional elements active at the time of sediment deposition is necessary to formulate basin scale models the prograding coastal depositional systems of sarawak all contain domed peat accumulating environments in which low ash low sulfur peats are being deposited in areas of active clastic siliciclastic sedimentation these depositional systems are as large as 11 400 km2 and individual peat deposits within systems are in excess of 20 m thick and 1000 km2 in area the geographic positions and drainage basin areas of each depositional system are controlled by fault and fold systems although prograding into the same receiving basin individual system geomorphology is variable and ranges from a wave dominated microtidal delta to a wave dominated meso to macro tidal delta coastal plain system to a tide dominated macrotidal estuarine embayment along a 450 km stretch of coastline system variation is a function of sediment supply shelf and embayment geometry wave climate and tidal range these factors which control depositional system geomorphology also control the resulting long axis orientation of the thick domed peat deposits the surface vegetation and internal characteristics of most domed peat deposits however are similar internal characteristics consist of basal high ash high sulfur degraded peats overlain by low ash low sulfur well preserved peats in vertical profile these systems demonstrate variable responses to late pleistocene holocene sea level rise and in these instances the variation is most attributable to local differences in siliciclastic sediment supply which is a function of the drainage basin area

spatial variability in modern tropical peat deposits from sarawak malaysia and sumatra indonesia analogues for coal petrographic and chemical variability in two tropical low ash domed peat deposits of similar age and physiographic setting but different external morphology were examined as modern analogues for coal both occur in microtidal alluvial to deltaic plain settings support similar arborescent vegetation and have accumulated in the past 5 000 years one deposit is an extremely convex mature done with a surface that rises 10 m above river level the other is a low gradient dome rising only 3 m above river level but with a concave base up to 6 m below both deposits have been eroded by adjacent rivers yet peat in the mature dome has accumulated remote from persistent flooding and exhibits distinctive internal stratigraphy decomposed sapric peat floors the deposits and is overlain by increasingly better preserved woody hemic and a cap of coarse fibrous peat derived from less arborescent vegetation consistent flooding in the low gradient dome has maintained conditions for the accumulation of predominantly woody hemic peat which interfingers with and is overlain by oxidised sapric peat and levee derived clastic sediments peat types in both deposits exhibit distinctive polymodal textures and organo chemical signatures that correspond to botanical input and degree of decay due to the abundance of pre huminite vitrinite macerals in all peat types from these deposits megascopic and microscopic texture is a better discriminator for comparison to ancient coal types it is suggested that the upward vertical sequence of decreasing woodiness and increasing lightness in colour observed in the mature dome might best be compared to sequences observed in tertiary brown coals this typical sequence can be modified or overprinted due to flooding in the burial process

geochemistry of sauceboats excavated from independence national historical park philadelphia evidence for a bonnin and morris c 1770 73 provenance and implications for the development of nascent american porcelain wares abstract porcelain sauceboats excavated from a privy with a late 18th century 1786 or later context at independence national historical park inhp are anomalously al rich compared with previously analysed anglo american sulphurous phosphatic wares apart from their s content they are most similar to phosphatic w m reid porcelain brownlow hill liverpool c 1755 67 and its branch at shelton staffordshire in terms of their major element constituents but they contain heavy minerals e g tio 2 polymorphs and in this regard resemble a dated 1773 silicious aluminous calcic s a c bonnin and morris porcelain philadelphia openwork porcelain basket in terms of morphology and composition some tio 2 polymorphs in the 1773 basket match those from clay from white clay creek delaware a resource reputedly exploited by bonnin and morris their high nb cr ratios indicate derivation from a metapelitic or granitic pegmatite source so too do some from the inhp sauceboats although others are chrome rich 1 cr 2 o 3 indicating a mafic source the bedrock beneath white clay creek includes metasediments granitic pegmatite and metabasites e g of the wissahickon formation pointing to a local source for the tio 2 polymorphs in the porcelains described here although the evidence for a bonnin and morris provenance for the inhp sauceboats is circumstantial their enrichment in heavy minerals unusual perhaps experimental compositions and aesthetic characteristics nonetheless suggest a philadelphia origin for these artifacts the compositions of 18th century philadelphia porcelain support the contention that knowledge of phosphatic and s a c pastes originating in london was transferred first to staffordshire and liverpool and then to philadelphia perhaps via a potter by the name of w m ball

ice ages and nuclear waste isolation abstract the greatest natural threats to the integrity of the geological barriers to nuclear wastes isolated in cavities mined at depths between 400 and 800 m are likely during rapid retreats of future ice sheets the next major glacial retreat is expected at ca 70 ka well within the lifetime of high grade nuclear waste but it is not yet clear how long man s greenhouse effect may delay it this contribution discusses the potential problems posed to european waste isolation sites during erosion by ice and over pressurizing of meltwater and gasses in a lithosphere flexed by major ice sheets these depend on the target rocks and the location of the site with respect to the ice streams and margins of future ice sheets of particular size no sites are planned under the centres of future ice sheets in europe where end glacial earthquakes can be expected to reactivate major faults nor where ice can be expected to deepen and lengthen fjords along the atlantic coast sites in the alps may be vulnerable to radical changes in the patterns of glacial troughs the stability and geohydrology of sites in coastal areas beyond future ice margins are threatened by river gorges when sea level falls ca 125 m or in enclosed basins like the mediterranean ever lower the greatest problems are likely in lowland regions exposed by the rapid retreat of thick ice fronts where large lakes on or under thick warm based ice are dammed by more distal cold based ice groundwater in subhorizontal fractures dilated by glacial unloading may reach over pressures capable of hydraulically lifting megablocks of bedrock with fracture permeability and or the ice damming them so that less permeable substrates are susceptible to incisions eroded to depths of ca 360 at locations controlled mainly by ice topography kinematics and history

seismicity and seismotectonics of norway and nearby continental shelf areas the earthquake activity of norway and nearby offshore areas is low to intermediate with few events above magnitude 5 recent significant improvements in instrumental coverage in parallel with a better utilization of older including historical data have shown that the seismicity in the south is predominantly confined to the coastal areas and to the viking graben while from the northern north sea to svalbard the earthquakes in a broad sense follow the continental margin fifty one focal mechanism solutions from these areas about half of them new reveal stress directions that clearly indicate a connection to the plate tectonic ridge push force at least for the areas at a minimum distance from the continental margin along the margin stress directions also indicate a possible connection to postglacial uplift as well as to lithospheric loading effects a dominance of normal faulting on the landward side and reverse faulting on the oceanic side agrees with this interpretation on a regional level the seismicity in these areas correlate quite well with geologic features such as grabens fault zones fault complexes fracture zones and the margin itself indicating that these structures act in a general sense as weakness zones in the presence of a regionally more stable stress field in the northern north sea however an area with quite anomalous stress orientations with strike slip faulting is found in a region transitional between normal and reverse faulting most of the earthquake foci are confined to the presumably brittle parts of the crust but many events are also located quite close to and on both sides of the moho discontinuity

stress transfer in the storegga area offshore mid norway abstract the recently discovered large gas field ormen lange within the storegga submarine slide area offshore mid norway poses important questions as to the origin of these large submarine slides and their possible implications in terms of the safety of the development and the production in this respect the present study was initiated with the main objective of investigating the possibility of stress transfer as triggering mechanism for multiple earthquake occurrence and hence for the storegga submarine slide ca 8200 years before present bp stress changes following different scenario earthquakes along the selected faults in the area are modeled and computed for a number of cases using the coulomb failure criterion we demonstrate the possibility of large earthquakes triggering multiple ruptures along neighbouring fault segments the combined effect of the co seismic slip and strong ground shaking due to a large earthquake m 7 accompanied by the stress transfer on the optimally oriented normal fault planes which are analogous to the slide scar may have played an important role for the triggering of the storegga submarine slide

a late pleistocene and holocene pollen and charcoal record from peat swamp forest lake sentarum wildlife reserve west kalimantan indonesia abstract a preliminary palynological record is presented from a peat swamp forest in the upper kapuas river basin in west kalimantan although the record is discontinuous it provides a picture of changing vegetation riverine and swamp environments and climate through parts of at least the last 30 000 years during the late pleistocene the composition of both riverine and swamp forests was different to that of the holocene temperatures were cooler especially during the last glacial maximum as indicated by the presence of components of submontane and montane vegetation the presence of charcoal demonstrates that the tropical lowland forests experienced fire through the whole of the recorded period however charcoal values generally rise through the period suggesting increased human impact through time highest burning levels and forest indicators of disturbance indicate most intensive human impact within the last 1400 years

provenance and sediment dispersal in the rajang river delta coastal plain system sarawak east malaysia preliminary sedimentologic investigations were conducted in the rajang river delta coastal plain system in sarawak east malaysia to determine the processes and timing of siliciclastic transport and sedimentation in tropical peat dominated systems methods involved depth profiling and collection and analysis of bottom and suspended sediment load samples from channels and offshore areas and coring and trenching of subaerial channel shoreline and backswamp features the rajang delta occurs in an embayment formed by the folded mesozoic and cenozoic sediments of the central borneo massif it covers an area of 11 000 km2 and is physiographically separated into an alluvial valley floodplain an abandoned tidally flushed delta plain and an actively accreting rectilinear delta coastal plain from 50 to 80 of the surface area is covered by peat 1 to 20 m thick during the dry season of july august 1992 river channels varying from 2 to 45 m deep with discharge rates from 100 to approximately 3550 m3 s were carrying suspended sediment loads ranging from 0 to 2281 mg l at present approximately 8 2 x 10 10 kg yr of fine grained sediment is supplied to the system and areal accretion rates are over 1 0 km2 yr the structural configuration of the uplands receiving basin and subsequent drainage patterns and tidal influence results in a contradictory distribution of mature fine grained sediments in the channels of the active delta coastal plain and immature coarse grained angular sands and gravels in the channels of the abandoned delta lobe the contemporaneity of the peat and clastic accumulation is evidenced by the margins of the thick domed low ash peat deposits interfingering with and being overlain by root penetrated siliciclastic sediments much of the fine grained sediment however bypasses the delta plain due to in channel density gradients delta coastal plain accretion occurs by distributary mouth bar buildup sand bar welding and ridge and runnel accretion all subaerially exposed surfaces are quickly vegetated the aberrant depth and configuration of some channels suggest that drainage is in part controlled by contemporaneous faulting

glacio seismotectonics ice sheets crustal deformation and seismicity abstract the last decade has witnessed a significant growth in our understanding of the past and continuing effects of ice sheets and glaciers on contemporary crustal deformation and seismicity this growth has been driven largely by the emergence of postglacial rebound models pgm constrained by new field observations that incorporate increasingly realistic rheological mechanical and glacial parameters in this paper we highlight some of these recent field based investigations and new pgms and examine their implications for understanding crustal deformation and seismicity during glaciation and following deglaciation the emerging glacial rebound models outlined in the paper support the view that both tectonic stresses and glacial rebound stresses are needed to explain the distribution and style of contemporary earthquake activity in former glaciated shields of eastern canada and fennoscandia however many of these models neglect important parameters such as topography lateral variations in lithospheric strength and tectonic strain built up during glaciation in glaciated mountainous terrains glacial erosion may directly modulate tectonic deformation by resetting the orogenic topography and thereby providing an additional compensatory uplift mechanism such effects are likely to be important both in tectonically active orogens and in the mountainous regions of glaciated shields in general the short term response to ice fluctuations is similar to the earth s response to fluctuations in water reservoirs with the subsequent increase or decrease in seismicity which depends on the pre existing stress state when the ice fluctuations occur on the spatial scale and magnitude of the late pleistocene glaciation and deglaciation however the viscoelastic response of the earth especially the mantle causes significant changes in crustal deformation and earthquake activity that is spatially extensive and temporally complex the regions of greatest ice thickness and the regions marginal to the late pleistocene ice sheets indicate the most dramatic evidence of earthquake faulting the mantle response to these large ice mass fluctuations and the change in mass between the oceans and land caused and continues to cause measureable crustal deformation at hundreds of kilometres from the ice margins for both tectonically active and cratonic regions palaeoseismic investigations of late pleistocene and holocene faults are an important tool in evaluating earthquake hazard the predicted response of the earth over this time however is very dependent on the model assumed for most regions far more carefully designed field observations are needed to constrain the existing rheological and ice models

the geology botany and chemistry of selected peat forming environments from temperate and tropical latitudes abstract peat has been studied in several geologic settings 1 glaciated terrain in cold temperate maine and minnesota u s a 2 an island in the atlantic ocean off the coast of maine where sea level is rising 3 the warm temperate u s atlantic and gulf coastal plains where sea level has changed often and 4 the tropical coast of sarawak malaysia and the tropical delta of the batang hari river sumatra indonesia most of these deposits are domed ombrotrophic or partly ombrotrophic bogs in which peat accumulation continued above the surface of the surrounding soil however the bogs of the u s atlantic and gulf coastal plains are comparatively not as domed and many have almost level surfaces in some bogs aquatic or semi aquatic plant materials accumulated replaced water in the depressions and formed a surface on which marsh or swamp vegetation could subsequently live die and accumulate in others the plant materials accumulated initially on level silt or sand surfaces supporting marshes or swamps as the peat dome formed plants growing on it changed from luxuriant ones near the base of the dome where nutrients were brought into the bog by surface and ground water to stunted ones at the top of the dome where the raised bogs are fed by nutrient poor precipitation the physical and chemical changes that take place in the sequence of environments from the pond stage of deposit development through the grassy marsh stage through the forested swamp stage and finally through the heath dome stage can be measured in terms of acidity and ash volatile matter carbon hydrogen nitrogen sulfur and oxygen contents as well as in the kind and distribution of trace elements the organic and inorganic contents of the deposits relate to geomorphology and geomorphology relates to their settings as models of coal formation some domed peat deposits may help in solving problems of distribution and character of ancient coal beds but clearly not all peat deposits are precursors of coal most holocene peat deposits are subject to destruction by erosion fire and decomposition through microbial and chemical oxidation before burial the best environments for coal precursors have biomass accumulation a continuously rising water table within the mass and minimum influx of clay and silt until preservation by burial the most suitable settings for future economic coal deposits are domed bogs that accumulate thick widespread peat having low ash and low sulfur contents the ombrotrophic peat deposits of tropical sarawak and sumatra are thick and extensive contain low ash and low sulfur peat and have high heating values they are considered to be the best tropical coal analogs because of their extent and chances of preservation the base of the peat is below adjacent river levels and chemical and structural conditions are favorable for accumulation

holocene sea levels and palaeoenvironments malay thai peninsula southeast asia sedimentological and palynological investigations of great songkhla lakes east coast of the malay thai peninsula southeast asia reveal sedimentary sequences rich in palynomorph assemblages dominated by pollen of mangroves and freshwater swamps compared with other regions in southeast asia the assemblages are of relatively low diversity geochronological data indicate that the great songkhla lakes record one of the earliest mangrove environments in southeast asia 8420 8190 cal yr bp which are subsequently replaced by a freshwater swamp at 7880 7680 cal yr bp owing to the decline of marine influence sea level observations from great songkhla lakes and other areas of the malay thai peninsula reveal an upward trend of holocene relative sea level from a minimum of 22 m at 9700 9250 cal yr bp to a mid holocene high stand of 4850 4450 cal yr bp which equates to a rise of c 5 5 mm yr the sea level fall from the high stand is steady at c 1 1 mm yr geophysical modelling shows that hydroisostasy

probabilistic and deterministic seismic hazard results and influence of the sedimentary more basin ne atlantic abstract seismic hazard assessments have been conducted for the ormen lange gas field in the norwegian sea on the flank of the more basin the study used logic tree based probabilistic methods combined with semi deterministic methods for hazard contributions from mapped faults and the hazard was computed in terms of peak ground acceleration pga and spectral acceleration the probabilistic seismic hazard results were complemented by deterministic modelling in 1d wave number integration and 2d finite difference crustal models the deterministic modelling first of all elucidated the shaking duration problem indicating that thick offshore sediment structures like the ones in the more basin may significantly extend the shaking duration of an earthquake the presence of sedimentary layers with large velocity contrasts are responsible for this observation and a conventional soil amplification analysis would not have revealed this phenomenon a modelling along similar lines as indicated in the present paper may be recommended in certain vulnerable situations and in geologic provinces with thick sedimentary layers with significant internal velocity contrasts even though large earthquakes most likely have occurred in the region during the postglacial period the study could not resolve if the huge storegga slide which occurred about 8100 yb was triggered by an earthquake

three dimensional numerical modeling of slip rate variations on normal and thrust fault arrays during ice cap growth and melting 1 changes in the volumes of ice caps considerably alter the stress state of the lithosphere by generating a transient signal that is added to the tectonic background stress field these stress field changes in turn affect crustal deformation and in particular the slip behavior of existing faults here we use three dimensional finite element models to investigate how arrays of normal and thrust faults near a growing and subsequently melting ice cap are influenced in their slip evolution the results show that regardless of fault dip both types of faults experience a decrease in their slip rate during ice cap advance and an increase in their slip rate during ice cap retreat if they are located beneath the ice cap in contrast faults outside the ice cap that are loaded on their footwall or hanging wall only show the opposite pattern their slip rate increases during glacial loading and decreases during subsequent unloading if the load is located along strike of the fault that is at one of its tips the slip behavior of normal and thrust faults is different the normal fault shows a slip rate increase during unloading the thrust fault during loading our results explain the location and timing of deglaciation induced paleoearthquakes in scandinavia and the contrasting slip histories reported from normal faults in the basin and range province which are located at different positions relative to the former yellowstone ice cap more generally our findings imply that a uniform slip behavior of faults in formerly glaciated regions should not be expected

response of salt structures to ice sheet loading implications for ice marginal and subglacial processes abstract during the past decades the effect of glacioisostatic adjustment has received much attention however the response of salt structures to ice sheet loading and unloading is poorly understood our study aims to test conceptual models of the interaction between ice sheet loading and salt structures by finite element modelling the results are discussed with regard to their implications for ice marginal and subglacial processes our models consist of 2d plane strain cross sections which represent simplified geological cross sections from the central european basin system the model layers represent i sedimentary rocks of elastoplastic rheology ii a viscoelastic diapir and layer of salt and iii an elastoplastic basement on top of the model a temporarily variable pressure simulates the advance and retreat of an ice sheet the durations of the individual loading phases were defined to resemble the durations of the pleistocene ice advances in northern central europe the geometry and rheology of the model layers and the magnitude spatial distribution and timing of ice sheet loading were systematically varied to detect the controlling factors all simulations indicate that salt structures respond to ice sheet loading an ice advance towards the diapir causes salt flow from the source layer below the ice sheet towards the diapir resulting in an uplift of up to 4 m the diapir continues to rise as long as the load is applied to the source layer but not to the crest of the diapir when the diapir is transgressed by the ice sheet the diapir is pushed down up to 36 m as long as load is applied to the crest of the diapir during and after ice unloading large parts of the displacement are compensated by a reversal of the salt flow plastic deformation of the overburden is restricted to the area immediately above the salt diapir the displacements after unloading range between 3 1 and 2 7 m larger displacements are observed in models with deep rooted diapirs thicker ice sheets longer duration of the loading phase thicker salt source layers and lower viscosity of the salt the rise or fall of diapirs triggered or amplified by ice sheet loading are likely to affect glacigenic deformation erosion and deposition above the diapir and within the rim synclines ice load induced uplift in front of an ice sheet will provide favourable conditions for the formation of push moraines for example by creating a topographic obstacle and inclining potential detachments subglacial subsidence of salt structures will enhance erosion by providing a preferential drainage pathway and fracturing of the overburden of the salt structure and thereby contribute to the incision of tunnel valleys however the resulting displacements are probably too low to have a marked effect on the advance or retreat pattern of the ice sheets

quantification of risks associated with seabed instability at ormen lange the ormen lange gas field is located within the slide scar of the enormous storegga slide that took place about 8200 years ago there are strong indications that the storegga slide generated a tsunami wave hitting the coastlines of norway scotland and the faeroes the headwalls of the storegga slide are steep and their safety factor against sliding could be low an extensive study was therefore performed to evaluate the probability for new submarine slides and their potential consequences results of the study showed that the 1st party and 3rd part risks associated with potential slide activity in the ormen lange area are negligible

too little too late the geochemistry of a 1773 philadelphia porcelain openwork basket abstract a dated 1773 openwork basket labelled philadelfia attributed to the bonnin and morris factory has a lead bearing silicious aluminous calcic s a c composition that contrasts with the phosphatic bone ash porcelains known to have previously been made during the mid 1760s to early 1770s in what is now the united states the basket was underfired and so contains relics of a flint pb glass flux but kiln temperatures were nonetheless sufficient for subsolidus pseudowollastonite and anorthite to have been resorbed implying that the duration of firing soaking near peak kiln temperatures was insufficient to ensure thorough vitrification during cooling liquidus pseudowollastonite and silica polymorphs but not anorthite formed showing that the melt was confined to the tridymite pseudowollastonite cotectic above the trd wol an eutectic 1170 c in the sio 2 al 2 o 3 cao system rapid cooling is also indicated by quenched silica polymorphs in the relict glass particles although bonnin and morris employed some former bow london c 1743 74 workers the s a c wares initially produced by this factory are compositionally distinct from the 1773 basket which in this regard more closely resembles the body and glaze of a reputed chelsea triangle period london c 1745 49 vessel regardless of how they obtained this technology it is ironic that bonnin and morris chose to abandon phosphatic pastes in favour of what in britain had become an obsolete formula

induced stresses and fault potential in eastern canada due to a realistic load a preliminary analysis summary in order to understand the causal relation between postglacial rebound and earthquakes a simple disc load model is used to 1 calculate stresses induced in the lithosphere and mantle by glacial loading melting and postglacial rebound and 2 evaluate the effect of glacial loading rebound on the failure potential for earthquakes in the upper crust the dependence of the failure potential and the actual mode of failure on the coefficient of friction the ambient tectonic stress magnitude direction the stress due to the overlying rocks and lithospheric thickness are investigated prominent features of this paper are the inclusion of 1 a viscoelastic mantle and thus the migration of stress and 2 the ambient tectonic stress and overburden stress contributions in the calculation of the total stress field it is assumed that throughout the earth there are optimally oriented pre existing virtual faults that are initially close to but not at failure thus a time dependent quantity called dfsm related to the coulomb mohr failure criterion can be defined such that a negative value of dfsm would advocate faulting or earthquake activities whereas a positive value of dfsm would promote stability the results indicate that under all combinations of tectonic stress magnitude and overburden stress crustal loading promotes fault stability directly underneath the load upon the removal of the load thrust faulting is predicted within the ice margin if the horizontal stress s induced by the overburden is greater than or equal to the vertical component s of the overburden stress 121 where sjs under this condition theory predicts that faulting or earthquake activity should have reached a maximum immediately after deglaciation if the horizontal stress induced by the overburden is less than the vertical component of the overburden stress 1 l then theory predicts fault stability within the ice margin the theory predicts fault instability both north and south of the ice margin the mode of failure however is completely determined by the value of i the trade off between the tectonic stress magnitude and the overburden stress parameter 1 is also investigated it is shown that a larger tectonic stress magnitude can be used to compensate a smaller value of 1 the results of this analysis show that variations in the coefficient of friction lithospheric thickness and a ductile zone below the upper crust do not significantly affect the above conclusions

will earthquake activity in eastern canada increase in the next few thousand years knowledge of whether earthquake activity will increase in the next few thousand years is important for the planning of nuclear waste repositories assuming that fault instability portends earthquak

to what extent is the present seismicity of norway driven by post glacial rebound abstract the seismicity of scandinavia is low to intermediate in intensity and with magnitudes that rarely exceed 5 5 even so the seismicity is characterized by a great diversity in space and time related to the fact that its driving forces or sources of stress are multiple and also diverse in nature the dominant driving forces range from plate related such as ridge push through regional to local ones such as topography all however are somehow related to lateral inhomogeneities in lithospheric structure whereas it was earlier assumed that the post glacial uplift was the main cause for the seismicity of scandinavia we now conclude that the uplift may at most be playing a minor role along the coastal stretch of northern norway there are still some indications that the seismicity which is often shallow normal faulting and swarm related may be related to the still remaining glacial isostatic adjustment the flexuring that is needed to explain such behaviour could however also be related to erosion and sedimentation processes it will take more work to separate these potential driving forces

testate amoebae protozoa testacealobosea and testaceafilosea as bioindicators in the late quaternary deposits of the bykovsky peninsula laptev sea russia testate amoebae protozoa testacea were studied in the late quaternary permafrost deposits in the siberian arctic bykovsky peninsula of the laptev sea coast 71 40 71 80 n and 129 129 30 e the testacea associations studied reflect specific environmental conditions in paleocryosols which were controlled by the local micro relief as well as by regional climate conditions in total 86 species varieties and forms of testate amoebae were found in 38 pleistocene and holocene samples the rhizopods indicate that soil conditions at ca 53 000 14c years bp were probably rather similar to the modern cold and wet arctic tundra environment more moisture and warmer soil conditions were relatively favorable for rhizopods ca 45 300 43 000 14c years bp but it was significantly drier at about 42 000 14c years bp drier and colder environmental conditions were also present about 39 300 35 000 14c years bp the late pleistocene samples radiocarbon dated to 33 000 12 000 years bp are characterized by a low species diversity and density indicating that this period may have been extremely cold and dry this conjecture is also supported by the polymorphism of some species hydrophilic difflugia species mostly obligate hydrobiotes are broadly represented in the studied holocene samples the species composition and density of rhizopods in the majority of holocene samples suggest wet and relatively warm conditions changes in rhizopod assemblages during the last 53 000 years were not very dramatic mostly consisting of rare species and changes in the dominant species complexes during the pleistocene and holocene however these changes were more drastic during the pleistocene they were probably at least partly responsible for the disappearance of some rare testacean species such as argynnia sp

moment tensors state of stress and their relation to post glacial rebound in northeastern canada summary in the stable craton of northeastern canada moderate seismicity as well as glacial isostatic adjustment gia has been observed we investigate five earthquakes with moment magnitudes between 3 6 and 4 1 that have occurred in northern hudson bay since 2007 which may be triggered by gia focal mechanisms of the earthquakes are determined using a waveform fitting procedure for surface waves in which the best double couple mechanism is obtained through a grid search over strike dip and rake all events exhibit a thrust fault mechanism in general agreement with mechanisms of previously analysed earthquakes in that area stress inversion results incorporating our new mechanisms as well as previously published results exhibit significant differences from previously calculated stresses from gia models for the first time maximum horizontal stress direction shmax is compared to the modelled stress values for northeastern canada we find that the maximum horizontal stress direction strikes roughly nnw sse in contrast to previously inferred ne sw orientation of shmax our results indicate that the local stress field in northern hudson bay deviates from regional stresses resulting from the existence of a roughly e w oriented zone of faulting which is not included in existing gia models

millennial scale trends in west pacific warm pool hydrology since the last glacial maximum models and palaeoclimate data suggest that the tropical pacific climate system plays a key part in the mechanisms underlying orbital scale and abrupt climate change atmospheric convection over the western tropical pacific is a major source of heat and moisture to extratropical regions and may therefore influence the global climate response to a variety of forcing factors the response of tropical pacific convection to changes in global climate boundary conditions abrupt climate changes and radiative forcing remains uncertain however here we present three absolutely dated oxygen isotope records from stalagmites in northern borneo that reflect changes in west pacific warm pool hydrology over the past 27 000 years our results suggest that convection over the western tropical pacific weakened 18 000 20 000 years ago as tropical pacific and antarctic temperatures began to rise during the early stages of deglaciation convective activity as inferred from oxygen isotopes reached a minimum during heinrich event 1 ref 10 when the atlantic meridional overturning circulation was weak pointing to feedbacks between the strength of the overturning circulation and tropical pacific hydrology there is no evidence of the younger dryas event in the stalagmite records however suggesting that different mechanisms operated during these two abrupt deglacial climate events during the holocene epoch convective activity appears to track changes in spring and autumn insolation highlighting the sensitivity of tropical pacific convection to external radiative forcing together these findings demonstrate that the tropical pacific hydrological cycle is sensitive to high latitude climate processes in both hemispheres as well as to external radiative forcing and that it may have a central role in abrupt climate change events

8000 years of vegetation dynamics and environmental changes of a unique inland peat ecosystem of the jambi province in central sumatra indonesia abstract despite their importance as global carbon sinks peatlands of southeast asia have been rarely studied and our current knowledge of the dynamics and ecology of these ecosystems remains incomplete paleoecological and palynological multi proxy analyses including analysis of pollen spores charcoal testate amoebae and sediments were carried out on a 733 cm long core taken from the air hitam peatland in the jambi province central sumatra indonesia the radiocarbon chronology reveals that peat formation started ca 7800 years ago the site was covered by dipterocarp swamp mixed rainforest during the first 2000 years after which freshwater swamp taxa became more important in particular durio trees this lasted until ca 4500 years ago when the swamp vegetation shifted to a pole forest with abundant pandanus thickets in response to a system change from minerotrophic to ombrotrophic conditions for this period macro charcoal analysis reveals that fire frequency increased possibly as a consequence of climate change linked to the onset of the modern el nino southern oscillation enso in the late holocene the ombrogenous pandanus pole forest phases were characterized by lower water table fluctuations and higher peat accumulation rates the area of air hitam has been for thousands of years a highly effective carbon sequestering peatland natural climate variability in the past did not affect the carbon storage function as suggested by the general increase in peat accumulation during relatively drier phases and increasing enso variability in the late holocene however the recent changes caused by selective logging drainage and conversion to oil palm plantations have caused a decline in the peat swamp forest communities changing the ecological functions of the peatland it is likely that the accumulated carbon will be released in the atmosphere due to exposure to aerobic conditions and its function will be lost unless a better management of the watershed is applied

seismo and neotectonics in finnmark kola and the southern barents sea part 2 seismological analysis and seismotectonics abstract a detailed review and analysis of seismological data acquired since 1979 from finnmark kola and the southern barents sea has provided a much improved delineation of the earthquake activity in that region in the barents sea the seismicity is confined only to the western areas while the finnmark kola coastal areas show some seismicity only north and east of murmansk in the rybachi cape tereberski region further inland there are several clear seismicity lineations that to some extent can be correlated with postglacial faults including the ne sw striking stuoragurra fault in finnmark the spatial correlation between seismicity and mapped faults is interpreted in general as a reflection of broad zones of weakness that respond to the present day stress field a detailed analysis of the earthquakes in this area has also shown a dynamic consistency in that they reveal a reverse faulting pattern that is consistent with a detailed geological study that includes a core drilling the dominant horizontal stress direction in this region is nnw sse consistent with the ridge push effect

on the significance of sea level variations and shelf paleo morphology in governing sedimentation in the southern south china sea during the last deglaciation abstract deglacial sedimentation on the outer sunda shelf the shelf margin and slope shows a close correlation with the stages of flooding of the emerged shelf it is mainly controlled by the relationship between shelf paleo physiography and changes in sea level and sediment supply based on the sedimentological and geochemical variability at five sites along a transect across the outer shelf and the continental slope covering the last 20 000 years four intervals of significant depositional changes are identified the first reorganization in the sedimentation regime which was established during sea level lowstand is associated with the drowning of the lower course of the north sunda river between 16 5 and 14 5 ka during and following the rapid rise in sea level at 14 5 14 ka sedimentation on the slope is characterized by an accelerated decrease in the supply of terrigenous material associated with the flooding of the middle part of the paleo valley this abrupt change in sedimentation is followed by a period of gradual decrease of terrigenous supply to the slope when the surrounding plains of the river valley were flooded 14 8 5 ka the final change occurred between ca 8 5 and 6 ka when the coastline reached its modern position and modern sedimentary patterns are established this change probably marks the end of reworking by transgression given the synchroneity of sedimentological changes along the transect across the sunda shelf and into the deep sea with the environmental shifts on the central shelf sedimentation on the margin and slope appears to be mainly controlled by the interrelationship of sea level shelf paleo physiography and sediment supply moreover the records display lateral changes through time associated with stages of the deglacial transgression which mask any potential sedimentological variability due to changes in precipitation vegetation or atmospheric circulation this fact cautions the interpretation of near shore sedimentary records as unequivocal recorders of local climate change e g se asian monsoon and highlights the need to include variations in shelf physiography and sea level in future paleoceanographic studies

suppression of earthquakes by large continental ice sheets the interior regions of antarctica and greenland are aseismic no earthquake larger than body wave magnitude 4 5 5 0 is known for either except along coastal zones or continental shelves here i advance an explanation for this lack of seismic activity in terms of pressure effects produced by the continental ice sheets that mantle both continents

ormen lange an integrated study for the safe development of a deep water gas field within the storegga slide complex ne atlantic continental margin executive summary abstract a great effort has been undertaken to investigate potential geohazards in relation to the development of the ormen lange gas field offshore mid norway the field is located in the scar left after the giant tsunami generating storegga slide which occurred roughly 8150 years ago and the slide risk has consequently received particular focus the studies have been multi disciplinary in character and have involved a number of companies universities and research institutions the results of the project have lead to a significant advance in our understanding of the storegga slide in particular and submarine slope instability in general and played an important role in the approval of field development by norwegian authorities this special issue comprises 26 individual contributions in addition to this representing the wide span of topics addressed in the project and this introductory paper gives a brief summary of their contents

new classification systems for tropical organic rich deposits based on studies of the tasek bera basin malaysia most schemes in common use for field and laboratory classification of peats were developed in boreal and humid temperate regions and do not recognize the distinctive features and specific uses of tropical peats such as those of the tasek bera basin in tropical peninsular malaysia the important aspects of peat texture morphology of constituents and their arrangement and laboratory ash content residue after ignition need modification to be valuable for classifying these and other tropical peat deposits in the tasek bera basin most of the deposits would not be considered as peat according to some classification schemes even though most have c contents 25 we propose a new three group fibric hemic sapric field texture classification applicable to tropical organic deposits which is similar to the system of the us soil taxonomy the classification is based on the following factors 1 visual examination of the morphology of the peat constituents texture and 2 estimates of fiber content and matrix finest fraction of peat consisting of highly humified organic matter and inorganic material the classification is applicable to all organic deposits with 35 loss on ignition we also present a new laboratory classification of organic soils based on ash and c content the us soil taxonomy classifies organic soils as having more than 12 18 organic c depending on clay content ash content and these limits for organic soils allow the discrimination of four main groups peat muck organic rich soil sediment and mineral soil sediment peat is defined as having an ash content of 0 55 muck 55 65 organic rich soil sediment 65 80 and mineral soil sediment 80 100 the peat class is further subdivided into very low ash 0 5 low ash 5 15 medium ash 15 25 high ash 25 40 and very high ash 40 55 subclasses

on a possible connection between three major earthquakes in california and oil production abstract the 1983 coalinga m 6 5 the 1985 kettleman north dome m 6 1 and the 1987 whittier narrows m 5 9 earthquake sequences each occurred beneath major producing oil fields and caused an aftershock sequence whose epicentral extent coincides approximately with that of the overlying oil field despite this coincidence a causal relationship between these sequences and oil production has been discounted because the earthquakes were located at depths of the order of 10 km whereas oil production is confined to the topmost several km moreover because all three oil fields coalinga kettleman north dome and montebello are situated on anticlines that have undergone recent uplift as a consequence of horizontal tectonic compression of the crust natural earthquakes are not unexpected a mechanical connection between oil production and the earthquake sequence is suggested however by the observation that in each case the total seismic deformation was just that required to offset the force imbalance caused by oil production specifically for each of the three sequences m 0 2 m c where m 0 is the sum of the seismic moments is the modulus of rigidity m is the mass of the fluid removed due to oil production is the fraction of the upper crust that is seismogenic and c is the average upper crustal density in essence net extraction of oil and water reduces slightly the average density of the upper crust causing an isostatic imbalance the ductile lower crust deforms in response to this imbalance thus increasing the load on the seismogenic layer which fails seismically to thicken the crust so as to restore static equilibrium locally accordingly earthquakes near the base of the upper crust may be an expected outcome of major oil production from growing anticlines irrespective of the depths of the producing formations

late pleistocene and holocene development of the interior peat accumulating basin of tropical tasek bera peninsular malaysia the stratigraphy of holocene peat deposits from an interior lowland basin of tropical peninsular malaysia provides insight into the hydrological ecological and climatic controls on tropical peatland development interpretations about vegetation and climate dynamics including storm intensity over the past 5000 years are integrated with regional and global climatic and eustatic changes to serve as a proxy for past ecology and climate tasek bera basin tbb is a lowland dendritic basin in tropical peninsular malaysia accumulation of organic matter occurred in local lakes during the last glacial maximum lgm but widespread peat deposition did not start until 5300 bp when climatic changes led to the evolution of a wetland system peat accumulation progressively expanded with terrestrialisation of channels and subbasins to paludification of the riparian part of the lowland forest zone lithofacies can be distinguished despite the highly diverse peat and organic rich sediment composition as a result of the climatic and hydrologic changes over the past 5300 years peat accumulation rates ranging from 0 7 to 2 5 mm year are highest in pandanaceae environments and lowest in high ash swamp forests and environments dominated by cyperaceae transects of peat cores across the mire system show the stratigraphic complexities of the peat is the result of hydrological variations and thus plant successional changes ash yield shows that periods of high mineral matter input into the drainage system occurred since the mid holocene indicating rapid and cyclic changes in frequency and magnitude of runoff events and by inference storms stratigraphic analysis of peat and ash yield are tools that provide a proxy for development of holocene hydrologic events in topogenous peat deposits

geochemistry of wistarburgh glass ca 1739 1777 implications for batch recipes and distinction from other south jersey wares the wistarburgh factory was america s first successful glassworks since it operated largely prior to the american revolution little is known about its products and confusion surrounds the authenticity of some of the objects attributed to this factory however analysis of alkali lime glass sherds from the glassworks site shows that green wistarburgh bottle glass is much more calcic and is enriched in various trace elements notably the rare earth elements compared with later south jersey glass for which analytical data are available the compositional data indicate that wistarburgh s proprietors made use of a batch recipe containing approximately 68 wt local sand 24 dolomitic limestone and 3 each of soda ash and potash in addition to green bottle glass blue aquamarine and colourless potash lead glass and colourless potash glass were also recovered from the wistarburgh factory site suggesting that a range of specialized glasswares was produced by this factory resume l usine de wistarburgh a ete la premiere productrice de verre en amerique du nord les produits de cette usine qui fut surtout en production avant la revolution americaine ne sont cependant pas tres bien connus et des doutes persistent concernant la vraie provenance de plusieurs objets attribues au site de wistarburgh l analyses d eclats de verre de couleur verte trouves au site demontre cependant que ce verre est plus riche en calcium et en divers elements traces en terres rares particulierement que les autres types de verres de cette region les donnees de composition indiquent que le verre de wistarburgh a ete cree a partir d un melange de 68 de sable local 24 de calcaire dolomitique 3 d ecarbonate de sodium anhydre e t3 d e potasse en plus des eclats verts des morceaux de verre bleu et sans couleur riches en potasse et en plomb et de verre sans couleur riche en potasse ont ete retrouves au site de l usine de wistarburgh et suggerent que plusieurs types de verres specialises ont etes manufactures a cet endroit owen 697

increasing australian indonesian monsoon rainfall linked to early holocene sea level rise the australian indonesian summer monsoon affects rainfall variability across the indo pacific region reconstructions of monsoon strength from stalagmites show that precipitation increased from 11 000 to 7 000 years ago as rising global sea level caused the flooding of the indonesian continental shelf the australian indonesian summer monsoon affects rainfall variability and hence terrestrial productivity in the densely populated tropical indo pacific region it has been proposed that the main control of summer monsoon precipitation on millennial timescales is local insolation1 2 3 but unravelling the mechanisms that have influenced monsoon variability and teleconnections has proven difficult owing to the lack of high resolution records of past monsoon behaviour here we present a precisely dated reconstruction of monsoon rainfall over the past 12 000 years based on oxygen isotope measurements from two stalagmites collected in southeast indonesia we show that the summer monsoon precipitation increased during the younger dryas cooling event when atlantic meridional overturning circulation was relatively weak4 monsoon precipitation intensified even more rapidly from 11 000 to 7 000 years ago when the indonesian continental shelf was flooded by global sea level rise5 6 7 we suggest that the intensification during the younger dryas cooling was caused by enhanced winter monsoon outflow from asia and a related southward migration of the intertropical convergence zone8 however the early holocene intensification of monsoon precipitation was driven by sea level rise which increased the supply of moisture to the indonesian archipelago

biomass burning in indonesia and papua new guinea natural and human induced fire events in the fossil record abstract microscopic charcoal preserved in sediments from ten wetlands in the indonesian and papua new guinea region provide a proxy record of regional fire events during the last 20 000 years two periods of high regional charcoal frequency are encountered during the last glacial transition 17 000 9000 years b p and the middle to late holocene 5000 years b p to the present despite the presence of humans in the region throughout the last 20 000 years there is no suggestion that on a regional spatial scale fire frequencies were solely related to changing subsistence patterns of the human population pollen data from these same sites suggest that during times of high charcoal the rate at which vegetation changes represented by the fossil pollen spectra also increases high climate variability may promote a greater community turnover rate and in turn a more fire susceptible forest community rapid climate change and high variability during the last glacial transition and intensification of el nino related climate variability during the middle to late holocene may have been important mechanisms for promoting fire in rainforest environments and maintaining diversity of tropical rain forests

petrology and organic geochemistry of peat samples from a raised bog in kalimantan borneo abstract two peat cores from the margin and centre of a tropical raised bog from the sebangau river near palangkaraya in kalimantan indonesia were investigated to illustrate the changes during peatification using coal petrographic and organic geochemical techniques these methods included a maceral analysis on polished peat blocks under reflected white and blue light excitation using the brown coal maceral nomenclature soxhlet extraction was carried out and an estimate of the humic composition was undertaken on the residues gc and gc ms analysis of the alkane and aromatic fractions were also made to identify biomarkers present in the peat results of this study show that peats from the margin of the raised bog were more decomposed than peats from the centre tissue content extract yield and alkaline insoluble acid soluble humic acid fraction support these results not only were there differences between the two locations of the peat cores but also differences arose with respect to depth in both cores the basal peats were more decomposed than the peats from the upper layers this was a result of their differing environments of deposition i e the basal peats were deposited under relative mesotrophic conditions and a more seasonal climate whereas the peats from the upper layers were deposited under acidic and oligotrophic conditions the biomarker composition of the alkane fraction included long chain n alkanes from n c 23 to n c 35 with an odd over even predominance and interestingly n alkanes from n c 36 to n c 40 with an even over odd predominance peaking at n c 38 pentacyclic triterpenoids were mainly represented by 17 21 h homohopane and hop 17 21 ene biomarkers in the aromatic fraction included polyaromatic triterpenoids derived from and amyrin