stratigraphy and paleoenvironmental evolution of the dinosaur rich baruungoyot nemegt succession upper cretaceous nemegt basin southern mongolia abstract portions of the dinosaur rich upper cretaceous baruungoyot nemegt succession are exposed in four geographic areas of the nemegt basin mongolia nemegt altan uul bugiin tsav and hermiin tsav lithostratigraphic correlations of these areas employ marker beds and non random stratigraphic patterns of lithology grain size variation and inferred paleoenvironments correlations suggest a minimum thickness of 350 m for the succession exposures at nemegt altan uul and bugiin tsav form a 100 km east west transect along the northern margin of the basin exposing 265 m of section from east to west the transect exposes higher portions of the succession extending from the uppermost baruungoyot formation and encompassing an almost complete section of the nemegt formation which has a minimum thickness of 235 m and can be consistently divided into three informal members lower middle and upper the lower nemegt is well exposed at nemegt and altan uul and is dominated by fluvial deposits the middle and upper nemegt are well exposed at altan uul 2 and bugiin tsav and consist of alluvial plain paludal lacustrine and fluvial deposits as confirmed by earlier studies the baruungoyot and nemegt formations exhibit an interfingering transition at nemegt the hermiin tsav section is a geographic outlier tens of kilometers west southwest of the northern transect it exposes about 150 m of section that overlaps with but is mostly lower stratigraphically than the northern transect the uppermost hermiin tsav section correlates with the lowermost nemegt section and also exhibits an interfingering contact between the baruungoyot and nemegt formations the remaining section at hermiin tsav comprises sediments of the baruungoyot formation 135 m that were deposited in alluvial fan fluvial paludal lacustrine and eolian environments and can be divided into two informal members designated as lower and upper the distribution of facies through the composite section records changes in paleoenvironments during the late cretaceous that may provide insights into the origins of the dinosaurian biostratigraphy

holocene climatic and human influences on lakes of the yucatan peninsula mexico an interdisciplinary palaeolimnological approach we used palaeolimnological techniques to examine effects of holocene climate change and human influence on lakes of the yucatan peninsula mexico the three study lakes are located along a west east transect that represents a gradient of increasing modern precipitation and density of former maya settlement at lake coba an 880 cm sediment core yields a complete record of lacustrine sedimentation that began when the lake first filled 8000 bp as groundwater level rose in response to rising sea level and increased precipi tation diatom ostracod and 18o evidence indicate that lake coba was initially shallow and saline coba presently in the region of greatest rainfall showed more episodic water level changes than lake san jose chulchaca or lake sayaucil high lake level and fresh water were evident at 440 cm 2600 bp followed by a decline in water levels and an increase in total ionic salinity to the present time in a 613 cm core from sayaucil in the intermediate precipitation zone total salini

non destructive pxrf of mafic stone tools abstract archaeological use of non destructive pxrf has been most systematically applied to the classification and provenancing of volcanic glass obsidian artefacts comparable work has yet to be developed for non vitreous artefacts we report results of pxrf analysis for a sample of grey to black mafic aboriginal hatchets from sydney and adjacent coastal regions to the north and south the study shows both broad and detailed classification is achievable depending on rock type and degree of elemental depletion or enrichment of the samples pxrf analysis reveals not only distinct patterns of resource use between the three regions of this study but also enables a high degree of geographic resolution in the case of the basalt artefacts of our sample we conclude that non destructive pxrf is effective for reliable characterisation of non vitreous stone artefacts that have a sufficiently complex and enriched compositional signature i e unaltered basalts with 50 of the basalt hatchets in our sample matched with spatially and geologically specific sources

a 4000 year lacustrine record of environmental change in the southern maya lowlands peten guatemala a 4000 yr sediment core record from lake salpeten guatemala provides evidence for maya induced forest clearance and consequent soil erosion between 1700 cal yr b c and 850 cal yr a d radiocarbon ages of wood seeds and charcoal support an age depth model with average errors of 110 cal yr relatively low carbonate 18o values between 1300 and 400 cal yr b c coincide with pollen evidence for forest loss consistent with increased surface and groundwater flow to the lake minimum 18o values between 400 cal yr b c and 150 cal yr a d suggest a high lake level as do 14c dated aquatic gastropods as much as 7 5 m above the present lake stage high lake levels resulted from reduced evaporation to precipitation ratios increased hydrologic input caused by anthropogenic deforestation or both the preclassic abandonment 150 a d and early classic late classic boundary 550 a d are marked by relatively high 18o values indicating reduced lake levels oxygen isotope composition increased further coincident with the terminal classic maya demographic decline between 800 and 900 a d this period of high 18o may have been caused by the greater aridity that has been documented in northern yucatan lakes or by decreased hydrologic input to the lake as a consequence of forest recovery reduced soil erosion after 850 cal yr a d coincided with the terminal classic maya demographic decline and permitted forest recovery and resumption of organic sedimentation

exhumation of a cretaceous rift complex within a late cenozoic restraining bend southern mongolia implications for the crustal evolution of the gobi altai region abstract the gobi altai region of southern mongolia contains intramontane basins dominated by jurassic cretaceous clastic and volcanic deposits the origin of the basins is poorly documented because late cenozoic transpressional mountain building and associated alluvial sedimentation have overprinted and obscured the older mesozoic history in this study we report the discovery of cretaceous high angle normal faults and a major low angle extensional detachment fault bordering the altan uul range in southern mongolia which indicates that nw se crustal stretching was responsible for creating the accommodation space for thick jurassic cretaceous sedimentary accumulations in southern mongolia the detachment fault separates chlorite grade metasedimentary rocks in the footwall from intensely sheared and flattened unmetamorphosed conglomerates and breccias in the hanging wall the significant metamorphic break across the detachment fault associated extensional structures in the hanging wall and domal form of the footwall block indicate that nw altan uul has some structural and topographic characteristics typically associated with metamorphic core complexes however nw altan uul lacks ductile extensional fabrics along the detachment fault and in the adjacent footwall and limited stretching in the upper plate suggests less total extensional slip than is reported from typical metamorphic core complexes unconformable relations in hanging wall strata and palynological data indicate that extensional detachment faulting at nw altan uul occurred in the aptian 120 112 ma similar in time to metamorphic core complex development previously reported in mongolia china border areas and the daqing shan of northern china post detachment fault cretaceous sedimentation buried nw altan uul which is now exposed only as a result of erosional denudation associated with uplift of the recent nemegt altan uul restraining bend the discovery of significant aptian crustal extension in the southern gobi altai suggests that early cretaceous diffuse rifting encompassed an even wider region than was previously recognized including areas of the eastern altai central southern and eastern mongolia and adjacent areas of northern and northeastern china and transbaikalia constituting one of earth9s largest continental interior extensional provinces workers investigating the neotectonic development of the gobi altai should consider the extent to which the pre existing rift basin architecture may have influenced the recent range development and network of seismically active faults in the region

long term behaviour of the late quaternary normal faults in the straits of messina area calabrian arc structural and morphological constraints abstract the calabrian arc is located in the peri tyrrhenian orogenic belt of southern italy and is characterised by intense post collision dynamics this consists of rapid regional uplifting combined with active normal faulting affecting the tyrrhenian side of calabria and the ionian coast of sicily the siculo calabrian rift zone the effects of the two combined processes are well exposed in the straits of messina area that represent a major transfer zone located between two opposing sets of normal faults characterising the southern calabria and the northeastern sicily branches of the rift in the straits of messina region the distribution and elevation of the upper quaternary marine terraces suggest a southward propagation of the normal fault belt from calabria to sicily it occurred at about 125 ka after a long period of tectonic quiescence and was triggered by huge elastic releases in southern calabria the long term behaviour recorded on the distinct fault segments of the rift is to relate to the presence of a crustal barrier that influenced both the geometry and the fault propagation along the rift zone

climate change on the yucatan peninsula during the little ice age we studied a 5 1 m sediment core from aguada x caamal 20 36 6 n 89 42 9 w a small sinkhole lake in northwest yucatan mexico between 1400 and 1500 a d oxygen isotope ratios of ostracod and gastropod carbonate increased by an average of 2 2 and the benthic foraminifer ammonia beccarii parkinsoniana appeared in the sediment profile indicating a hydrologic change that included increased lake water salinity pollen from a core in nearby cenote san jose chulchaca showed a decrease in mesic forest taxa during the same period oxygen isotopes of shell carbonate in sediment cores from lakes chichancanab 19 53 0 n 88 46 0 w and salpeten 16 58 6 n 89 40 5 w to the south also increased in the mid 15th century but less so than in aguada x caamal climate change in the 15th century is also supported by historical accounts of cold and famine described in maya and aztec chronicles we conclude that climate became drier on the yucatan peninsula in the 15th century a d near the onset of the little ice age lia comparison of results from the yucatan peninsula with other circum caribbean paleoclimate records indicates a coherent climate response for this region at the beginning of the lia at that time sea surface temperatures cooled and aridity in the circum caribbean region increased

chemistry microstructure petrology and diagenetic model of jurassic dinosaur bones dinosaur national monument utah abstract the fossil bone mineral in dinosaurs from the morrison formation is well crystallized stoichiometric francolite the closely packed subparallel francolite crystals have equidimensional cross sections mostly 10 40 nm wide in contrast crystallites in unaltered mammal bone tissue are poorly crystallized nonstoichiometric carbonate hydroxyapatite a few nanometers thick and plate rod or needle shaped the diagenetic francolite crystals are elongated in the c axis direction as are bone tissue crystallites along permeable cracks francolite crystals grew to 250 nm wide compared to unaltered crystallites in mammal bones the francolite has higher concentrations of ba ce cr f la mn ni pb rb sr th u v and y and perhaps zr na and mg are lower in concentration diagene ic francolite grew from groundwater enriched in ions from silicic ashes in the brushy basin member and from dissolution of bone tissue crystallites after burial francolite grew on crystallite seeds filling the space formerly occupied by collagen perhaps half the tissue volume and dissolved crystallites the micron scale structures such as haversian canals and laminae are preserved because the diagenetic francolite retains the orientations of the seeds the laminae 1 10 m thick commonly preserve an orthogonal plywood structure the diagenetic growth of francolite during this type of bone fossilization implies that oxygen isotopic ratios measured in dinosaur bones even those that appear fresh and unaltered may dominantly reflect groundwater temperature rather than dinosaur body temperature trace element concentrations in the francolite may reflect groundwater composition rather than dinosaur diet pore filling cements precipitated in the sands and bones at shallow burial depths as evidenced by the 35 52 minus cement porosities of the sandstones and numerous uncompacted oversize pores filled by cements gypsum and calcite were precipitated from shallow alkaline groundwater as the groundwater became increasingly dominated by ions from silicic ash argentite chalcopyrite native gold native silver tiemannite and uraninite replaced areas of bone a few microns to tens of microns in size along cracks a thin chlorite crust commonly mantled francolite crystals along bone cracks and lined openings in bones and sandstones pervasive precipitation of a chalcedony crust followed with pseudomorphs of chalcedony after gypsum in larger cancellous openings the remaining space was fi led by the various forms of silica the bones are brown due to goethite filled cracks that cut pore filling minerals

hydrology and alkalinity regulation of soft florida waters an integrated assessment natural waters in ridge provinces of florida and southeast georgia were classified geographically by degrees of cultural disturbance and according to the dominant hydrologic and biogeochemical processes controlling chemistry the ionic composition of lakes upland streams and surficial aquifer water table springs in relatively undeveloped catchments reflects the geographic variations in bulk deposition corrected for evapotranspiration na cl plus a slight gain net watershed mobilization of mg and partial to nearly complete losses net retention of nitrate sulfate ca and k recharge to the floridan aquifer in infertile forested sandy ridge provinces of northern florida contains 360 580 mol co2 on the basis of indirect geochemical evidence sulfate retention appears less important in lake sediments than in the region s highly weathered ferruginous kaolinitic sand soils silica concentrations in upland streams and water table springs closely reflect the predicted equilibrium between kaolinite and gibbsite along with other evidence the si concentrations in ridge lakes indicate that seepage inflow is much more important than assumed in baker et al s 1988 regional model lakes and streams are acidified either by humic acids or nonmarine sulfate but rarely by both as reflected by the significant inverse correlation between these two components contrary to previous reports there is no significant difference in alkalinity for culturally undisturbed lakes in the northern trail versus southern highlands ridge areas

high resolution maps of khulsan and nemegt localities nemegt basin southern mongolia stratigraphic implications abstract since the discovery of fossil rich exposures at the khulsan and nemegt localities nemegt basin southern mongolia tens of paleontological expeditions returned to these exposures which are considered some of the richest cretaceous units in the world however limited data on the local geology and cartography have been limiting our comprehension on correlations between different sites and the stratigraphic occurrence of vertebrate remains although informative hand drawn maps from the 1940s still represent the sole tool for researchers to provide a framework for locating access path quarries and major geological sections in 2016 we started a project for the realization of high resolution topographic maps of key localities within the nemegt basin based on drone acquired images several tests were performed at pivotal localities such as altan uul 2 and 3 tsagaan khushuu and ulaan khushuu providing partial maps of such localities whereas the nemegt and khulsan localities were fully covered photogrammetric elaboration of high resolution images resulted in digital surface models used to obtain high resolution topographic maps and orthophotos rock cairns used in the 1940s for triangulation were relocated and painted with vivid colors in order to represent reliable ground control points in this study we introduce new topographic maps for both khulsan and nemegt localities as well as comprehensive geological maps in so doing we provide additional stratigraphic and geographic data on the approximately 25 m thick interfingering interval that characterize the transition from the baruungoyot and overlying nemegt formations data presented in this study provide a solid framework in which detailed geological and paleontological investigations can be referred in order to significantly improve our comprehension on the late cretaceous nemegt ecosystems

the crustal assembly of southern mongolia new structural lithological and geochronological data from the nemegt and altan ranges abstract the gobi altai region is an ideal setting for studying processes of continental growth and subsequent intracontinental and intraplate deformation including terrane accretion and dispersal ophiolite obduction crustal reactivation and intraplate mountain building to assess the diverse tectonic evolutionary models of the gobi altai and the wider region more field data and geochronological data are required to constrain the tectonic evolution of individual terranes and the relationship of adjacent crustal domains to each other throughout time in this paper we present new lithological structural and 40ar 39ar age data which constrain the crustal evolution across a previously unreported late paleozoic terrane boundary in the gobi altai nemegt and altan nuruu are topographically linked mountain ranges that were formed by miocene recent uplift at a right stepping restraining bend along the left lateral gobi tien shan fault system in southern mongolia ordovician carboniferous arc rocks and an ophiolite are exposed in the mountain ranges and form a small part of the east west arcuate trans altai zone field observations of rock types and structures combined with petrographic data are used to distinguish metamorphosed volcano sedimentary arc rocks in altan nuruu and western nemegt nuruu from arc rocks in central and eastern nemegt nuruu these distinct sequences are correlated with the dzolen and edrengin terranes in the trans altai zone along strike to the west integration of field data 40ar 39ar age data and published studies are used to describe a polyphase deformation history that includes late carboniferous ophiolite obduction mid permian to late triassic shortening and lateral terrane redistribution cretaceous rifting and late cenozoic intraplate mountain building

terminal classic drought in the northern maya lowlands inferred from multiple sediment cores in lake chichancanab mexico we present new density records from sediment cores taken along a depth transect in lake chichancanab mexico the data reveal in great detail the climatic events that comprised the terminal classic drought tcd and coincided with the demise of classic maya civilization between ca 750 and 1050 ad in shallow water cores the tcd is marked by a condensed gypsum horizon in deeper water sections it is expanded and represented by numerous interbedded gypsum and organic rich strata the tcd was not a single two century long megadrought but rather consisted of a series of dry events separated by intervening periods of relatively moister conditions we estimate the tcd occurred between ca 770 and 1100 ad and included an early phase ca 770 870 ad and late phase ca 920 1100 ad the intervening 50 year period ca 870 920 ad was relatively moister each dry phase is represented by multiple gypsum density bands interbedded with organic rich sediment that indicate alternating dry and wet conditions spectral analysis revealed significant periods around 213 50 and 27 years despite uncertainty regarding the ages of these events their pattern is robust and generally consistent with other proxy records under the same climate regime such as the marine cariaco basin off northern venezuela science 299 2003 1731

mineral microbial structures in a bone of the late cretaceous dinosaur saurolophus angustirostris from the gobi desert mongolia a raman spectroscopy study abstract bones while buried undergo diagenetic transformations the intensity of which depends on a variety of geochemical factors microbial degradation is one of the main processes acting on bones during early diagenesis we present mineral microspheres formed during bone diagenesis from the inner walls of the left tibia of the late cretaceous dinosaur saurolophus angustirostris from the gobi desert mongolia the microspheres occur either as individual bodies from a few micrometers to about 70 m in diameter or aggregated in clusters micro raman analysis shows that the microspheres are composed of various fe oxides mostly hematite and goethite that form regular reddish brown rings with organic matter at their cores the bone itself is composed for the most part of diagenetically transformed carbonate fluorapatite calcite cement was identified around the spheres and at points of contact with bone tissue negative ce anomalies indicative of ce iv in the diagenetic environment indicate oxic burial conditions all the size distribution of the microspheres their mode of occurrence and the presence of organic matter in cores surrounded by concentric fe oxide envelopes indicate early diagenetic microbially mediated mineralization in aerobic conditions the presence of microspheres and other mineral phases in the studied bone gives evidence of at least two mineralization episodes 1 fe oxide formation during an early diagenetic microbial attack on the bone and 2 later calcite barite gypsum cementation

cultural and climatic history of coba a lowland maya city in quintana roo mexico abstract lake coba within the archaeological site of coba provides evidence bearing on lowland maya development palynological and geochemical data record multidecadal precipitation cycles from a 8 80 m 8370 yr lake sediment sequence terminating on bedrock late classic sedimentation rates are rapid but an anthropogenically derived colluvium layer is lacking initial vegetation was medium semi deciduous and swamp forest forest clearance began 1650 b c early preclassic and maize first occurred at 850 b c middle preclassic lakeside milpas existed until a d 720 late classic and then were moved from the city center as urbanization intensified and lake coba was diked as a reservoir coba was at most briefly vacated during the classic collapse and was abandoned after a d 1240 although some habitation persisted the paleoecological record matches the archaeological history for coba but pervasive disturbance muted the climatic signal as the late classic drought is barely evident the question whether economic trees were maintained within the city is unresolved maize cultivation allowed the maya to develop a complex society and support a large population but dependence on maize was ultimately doomed by variable rainfall precipitation in extreme years was insufficient to support crops while native vegetation was not directly affected by drought that devastated maya agriculture

climate variability on the yucatan peninsula mexico during the past 3500 years and implications for maya cultural evolution climate variability on the yucatan peninsula during the past 3500 yrs is reconstructed from the measurement of 18o in monospecific ostracods and gastropods in a 6 3 m sediment core from lake punta laguna mexico this late holocene record is divided into three periods based on changes in mean 18o values from 3310 to 178514c yr b p period i low mean 18o values indicate relatively wet conditions i e low evaporation to precipitation ratio e p mean oxygen isotopic values increased 178514c yr b p and the interval between 1785 and 93014c yr b p period ii was distinctly drier than the periods before or after the climate during the latter part of period ii was persistently dry with exceptionally arid events centered at 1171 1019 and 94314c yr b p equivalent to 862 986 and 1051 a d this interval of frequent drought was recorded at several other localities in mexico and central america and coincided with the collapse of classic maya civilization following the last arid event 18o values decreased abruptly at 93014c yr b p beginning of period iii signaling a return to wetter conditions that have generally prevailed to the present with the exception of a dry episode centered at 55914c yr b p 1391 a d the paleoclimatic record from punta laguna provides evidence that multi decadal and millennial scale changes ine poccurred on the yucatan peninsula during the late holocene these wet dry episodes may have influenced cultural evolution in mesoamerica

geochemical study of vertebrate fossils from the upper cretaceous santonian csehbanya formation hungary evidence for a freshwater habitat of mosasaurs and pycnodont fish abstract the diverse vertebrate remains from the upper cretaceous freshwater settings at iharkut hungary contain two fossil groups pycnodontiformes fish and mosasauridae that are almost exclusively known from marine palaeo environments hence their appearance in alluvial sediments is very unusual trace element and isotope compositions of the remains have been analyzed to investigate the taphonomy and the ecological differences among the different fossil groups present at iharkut all examined fossils have undergone post depositional diagenetic alteration which resulted in high concentrations of ree u and fe together with almost complete homogenization of 18oco3 values similar ree patterns in different fossils suggest a common origin for all remains hence the discovered species most likely lived in the same local ecosystem despite partial diagenetic overprinting the 18opo4 values of the fossils indicate sufficient taxon specific isotopic diversity to permit some broad conclusions on the palaeo environment of the fossils in particular it is apparent that the isotopic composition of the pycnodontiformes fish and mosasauridae remains is most compatible with a freshwater palaeo habitat and incompatible with a marine palaeo environment in addition the sr concentration and isotope data indicate that the pycnodontiformes and mosasauridae likely lived predominantly in a freshwater environment and were not simply occasional visitors to the iharkut river ecosystem regarding other fossil groups high 18opo4 values of alligatoroidea and iharkutosuchus teeth suggest that these small crocodile species might have inhabited swamps and ponds where the water was relatively rich in 18o due to evaporation

non destructive pxrf analysis of museum curated obsidian from the near east abstract non destructive pxrf has the potential to expand sample populations of archaeological provenancing studies by facilitating access to museum collections of artefacts in this study we use museum curated obsidian for the sites of tell brak mersin yumuktepe and tell arpachiyah and geological obsidian samples from central turkey to demonstrate that non destructive pxrf is comparable to other techniques in differentiating between near eastern obsidian sources secondly we use multivariate analysis to evaluate whether non destructive pxrf is sufficiently accurate and precise to enable comparison with legacy datasets from previous analysis using pixe and icp ms multivariate analyses show that instrumental offsets between the results from pxrf and other analytic techniques are less than source to source variation typical for most anatolian obsidian outcrops and pxrf identified geochemical groups are directly comparable to legacy datasets non destructive pxrf analysis indicates that during the chalcolithic east gollu dag and nenezi dag continued to be the major sources of obsidian to communities in central anatolia and the bingol range and mountains surrounding lake van supplied sites east of the levant variations in the analysed assemblages suggest a number of obsidian exchange networks existed during this period

subbottom acoustic and sedimentary records of past surface water groundwater exchange through sinkhole lakes in south georgia u s a lake balboa is a deep sinkhole lake in south georgia subbottom acoustic profiling and long sediment cores reveal four stratigraphic units within 20 m of lacustrine fill above acoustically stratified and faulted miocene pliocene overburden and basement eocene limestone which hosts the floridan aquifer system fas fill consists of thin rhythmically bedded peaty sediments unit i indicative of slow sedimentation in a shallow swamp until 13 110 12 680 cal bp a mix of desiccated and over consolidated clay and silty sand unit ii implying periodic subaerial exposure of the lake bed until 9470 9025 cal bp and gyttja associated with a rapid 8 m rise in water level by 9120 9020 cal bp unit iii as well as an additional rise of 10 m to modern lake levels unit iv accumulation of nearly 4 5 m of low permeability gyttja and higher lake levels have fundamentally changed exchange between surface water and groundwater reducing by 40 or more the rate of vertical leakage to the fas and increasing shallow aquifer discharge to the lake

a geochemical method to trace the taphonomic history of reworked bones in sedimentary settings rare earth element ree signatures can be used to identify the original mode of deposition of fossil bones and teeth that have been reworked this new technique may resolve the notoriously difficult problem of assessing the amount of transport or reworking undergone by fossil bones and teeth on the basis of physical parameters such as degree of abrasion different ree signals characterize different pore water environments bones and teeth composed of apatite incorporate rees rapidly during early diagenesis and the ree signature in the bone is controlled by that of the surrounding pore waters reworked bones and teeth may show ree traces suggesting early diagenetic pore water conditions different from those indicated by in situ sedimentary or geochemical evidence this situation is demonstrated in a case study from the rhaetian latest triassic of southwest england where different bone beds are compared in one case the original environmental setting of reworked bone is traced by matching ree traces with contemporaneous unreworked bone assemblages in neighboring areas

from bone to fossil a review of the diagenesis of bioapatite the preservation of bone or bioapatite over geologic time has presented paleobiologists with longstanding and formidable questions namely to elucidate the mechanisms processes rates and depositional conditions responsible for the formation of a fossil from a once living tissue approaches integrating geochemistry mineralogy physics hydrology sedimentology and taphonomy have all furthered insights into fossilization but several fundamental gaps still remain notably our limited understanding of 1 the timing of processes during diagenesis e g early and or late 2 the rate of bioapatite transformation into thermodynamically more stable phases 3 the controls imparted by depositional environment and 4 the role of micro biology in determining the fate of bone bioapatite dissolution or preservation the versatility of fossil bioapatite to provide information on the biology of extinct vertebrates rests on our ability to identify and characterize the changes that occurred to bioapatite during diagenesis this review will evaluate our current understanding of bioapatite diagenesis and fossilization focusing on the biogeochemical transformations that occur during diagenesis to the mineral and organic components of bone excluding teeth and enamel the analytical approaches applied to evaluate fossilization processes and outline some suggestions for future promising directions

vertical leakage and vertically averaged vertical conductance for karst lakes in florida in the karst lake district in peninsular florida in the southeastern united states as many as 70 of the lakes lack surface outlets and groundwater outflow is an important part of the water budgets of these lakes for 11 karst lakes in the central lake district vertical leakage from the lakes to the upper floridan aquifer averages 0 12 to 4 27 m yr 1 the vertically averaged vertical conductance kv b a coefficient that represents the average of the vertical conductances of the hydrogeologic units between the bottom of a lake and the top of the upper floridan aquifer was determined to range from 0 0394 to 1 00 yr 1 for these lakes for six of the lakes various hydraulic parameters previously calculated by other investigators are shown to be equivalent to the kv b values calculated in this study if kv b is determined for a lake then vertical leakage can be estimated for other conditions of lake stage and hydraulic head in the upper floridan aquifer using kv b for the lake and darcy s equation written for vertical flow the methodology described in this paper for quantifying kv b which requires only limited data i e vertical leakage lake stage and hydraulic head in the upper floridan aquifer could be used to investigate the apparent association between relatively large kv b values and lake level instabilities at some lakes in the central lake district and similar hydrogeologic settings this methodology for calculating vertical leakage is applicable to the central lake district in florida and to other similar lake and groundwater systems

oxygen and carbon isotope compositions of middle cretaceous vertebrates from north africa and brazil ecological and environmental significance in order to investigate mid cretaceous terrestrial climates of low paleolatitudes moroccan tunisian and brazilian vertebrate apatites have been analyzed for their oxygen and carbon isotope compositions of phosphates delta 18 o p and carbonates delta 18 o c delta 18 c c at each site coexisting theropod dinosaurs titanosaurid sauropods pterosaurs crocodilians turtles and fish have distinct delta 18 o p and delta 18 c c values reflecting their ecologies diets and foraging environments oxygen isotope compositions of surface waters delta 18 o w estimated from turtle and crocodile delta 18 o p values range from 5 0 1 0 parts per thousand to 2 4 1 0 parts per thousand which do not differ from mean annual rainwater values occurring today under inter tropical sub arid to arid climates high water temperatures ranging from 21 6 degrees c to 34 2 degrees c deduced from fish delta 18 o p values are in agreement with those published for mid cretaceous low latitudes temporary or seasonal droughts are inferred from high delta 18 o p values of lungfish teeth even though lower reptile delta 18 o p values suggest the use of distinct and most likely larger or regularly renewed bodies of water environmental conditions of the studied low latitude regions during the aptian cenomanian interval were somewhat similar to those experienced today under semi arid to arid tropical or equatorial climates but with higher mean surface temperatures than present day ones

visualizing fossilization using laser ablation inductively coupled plasma mass spectrometry maps of trace elements in late cretaceous bones elemental maps generated by laser ablation inductively coupled plasma mass spectrometry la icp ms provide a previously unavailable high resolution visualization of the complex physicochemical conditions operating within individual bones during the early stages of diagenesis and fossilization a selection of la icp ms maps of bones collected from the late cretaceous of montana united states and madagascar graphically illustrate diverse paths to recrystallization and reveal unique insights into geochemical aspects of taphonomic history some bones show distinct gradients in concentrations of rare earth elements and uranium with highest concentrations at external bone margins others exhibit more intricate patterns of trace element uptake related to bone histology and its control on the flow paths of pore waters patterns of element uptake as revealed by la icp ms maps can be used to guide sampling strategies and call into question previous studies that hinge upon localized bulk samples of fossilized bone tissue la icp ms maps also allow for comparison of recrystallization rates among fossil bones and afford a novel approach to identifying bones or regions of bones potentially suitable for extracting intact biogeochemical signals

determination of flow characteristics in the aquifer of the northwestern peninsula of yucatan mexico abstract flow characteristics were studied in the northwestern peninsula of yucatan mexico the yucatan aquifer is a mature karst system influenced by the ring of cenotes sinkholes this zone of aligned sinkholes is a high permeability zone with respect to its surroundings the aquifer is unconfined within the study area water level measurements at 48 locations were made in june and october 1994 they were measured up to four times in october water levels in a limited group of wells showed variations up to 60 during october 1994 whereas others had variations of the order of 5 in the same period by studying the resulting equipotential regimes a highly variable zone hvz was identified drain characteristics are significantly different from the rest of the study area which leads to the hypothesis that the hvz represents an independent subsystem of interconnected fractures to determine directions of high permeability within the study area azimuthal resistivity surveys were conducted at 22 locations resistivity curves particularly in the hvz show two or more peaks each indicating a direction of high permeability directions of high permeability are interpreted to be preferential directions of aligned fractures comparison with the two different equipotential regimes in october 1994 shows that in the majority of the cases the direction of the hydraulic gradient coincides with the direction of one fracture system the hydraulic gradient can be considered to be the major control in the dissolution process at least in the hvz resulting in the selective opening of the fractures peaks in the resistivity curves are of the same order of magnitude this shows that both regimes of equipotential lines and the corresponding changes of the hydraulic gradients are sufficiently frequent to be able to create different fracture systems with a comparable fracture density the variations of the equipotential regime in time may have severe consequences in terms of the risk of aquifer contamination in the highly variable zone contaminants generated mainly in the city of merida are generally believed to flow towards the north coast of the peninsula however reversals in the hydraulic gradient may allow contaminants to flow towards the southeast of the city at least for limited periods in the year

dinosaur eggshell and tooth enamel geochemistry as an indicator of mongolian late cretaceous paleoenvironments the late cretaceous fossiliferous beds of mongolia s gobi desert have yielded spectacular articulated remains of a remarkable diversity of fossil mammals lizards turtles birds and non avian dinosaurs paleoenvironmental interpretations of the deposits at these localities have ranged from arid wind blown dune fields to more mesic moist environments among the diversity of fossils dinosaur eggshells and teeth are commonly found at these localities dinosaur eggs like modern avian eggs are constructed of biomineralized calcite caco3 and proteins allowing carbon and oxygen stable isotopes to be quantified to provide information about the environment in which the egg laying animals were living here it is shown that dinosaur eggshell and teeth from the djadokhta and nemegt formations have not been significantly altered and reflect an environment of dry dunes during deposition of the djadokhta formation and a more mesic stream environment for conditions in the nemegt formation carbonate nodules from the same eggshell bearing layers also independently reflect a similar environmental signal this study represents the first geochemical analysis of dinosaur remains from the cretaceous of mongolia and illustrates the potential of utilizing dinosaur fossil geochemistry of both eggs and teeth to reconstruct mesozoic environments

chemical constraints of groundwater management in the yucatan peninsula mexico two critical objectives of water management in the yucatan are 1 to develop regional groundwater supplies for an expanding population and tourism based on the mayan archeological sites and excellent beaches and 2 to control groundwater pollution in a chemically sensitive system made vulnerable by geologic conditions the yucatan peninsula is a coastal plain underlain by permeable limestone and has an annual rainfall of more than 1000 mm such a setting should provide abundant supplies of water however factors of climate and hydrogeology have combined to form a hydrologic system with chemical boundaries that decrease the amount of available fresh water management of water resources has long had a major influence on the cultural and economic development of the yucatan the mayan culture of the northern yucatan developed by extensive use of groundwater the religion was water oriented and the mayan priests prayed to chac the water god for assistance in water management primarily to decrease the severity of droughts the spaniards arrived in 1517 and augmented the supplies by digging wells which remained the common practice for more than 300 years many wells now have been abandoned because of serious problems of pollution resulting from the use of a sewage disposal well adjacent to each supply well the modern phase of water management began in 1959 when the secretaria de recursos hidraulicos s r h was charged with the responsibility for both scientific investigations and development programmes for water supply and sewage disposal systems for cities villages and islands

genesis and geomorphologic and ecological evolution of the ganzirri salt marsh messina italy the results of geological and geomorphologic surveys on the salt marsh of ganzirri pantano grande combined with geophysical researches and historiographical data are reported here to define the genesis of the marsh and to evaluate the physical factors that influenced its recent evolution the genesis of the pantano grande may be due to a state of equilibrium reached between differential lowering of the coastal plain confined by normal faults and generalized chain uplift in particular two normal faults are considered the first borders the northern shore of the pantano grande and the second bounds the ionian coastal plain towards the south concerning the recent evolution of the pantano grande the importance of the sterile conglomerate outcrop which borders the ganzirri coastal plain is stressed the conglomerate is interposed between sediments that define the pantano grande basin and the ionian sea and influenced the water exchange between the marsh and the sea before the excavation of two canals that link up the pantano grande with the sea the conglomerate limiting the spread of benthic species has definitively affected the ecological structure of the original marsh

archaeological and historiographical implications of recent uplift of the peloro peninsula ne sicily abstract in ancient times the name peloro was used to indicate an anthropic area that gradually developed around the first known human settlement on the sicilian shore near the straits of messina since the 5th century bc historians have documented that numerous naval armadas landed for long periods at peloro however the present day morphology of the peloro cape peninsula does not have any protected inlet that would offer a location to repair hundreds of ships as has been documented by historical sources to address this discrepancy geomorphologic data were collected and analyzed to verify whether historical documents were consistent with the palaeotopography of the area this approach is based on the analysis of the morphotectonic evolution of the coastal lowland that resulted from regional uplift over the quaternary and holocene the results indicate that the harbour was located in the basin of the pantano piccolo salt marsh and was large and deep enough to have sheltered up to 320 ships

early diagenetic stabilization of trace elements in reptile bone remains as an indicator of maastrichtian late paleocene climatic changes evidence from the naran bulak locality the gobi desert south mongolia abstract maastrichtian dinosaur bone remains from the naran bulak locality the gobi desert with well preserved bone textural features are enriched in some trace elements primarily in ree these features of vertebrate fossils were formed during diagenesis following rapid burial in mudflow sediments and prior to postfossilization epigenetic changes trace elements are mainly concentrated in diagenetic apatite their contents in the bones correlate with that in their enclosing sediments for both maxima and minima fossil and sediment compositions were established under the influence of paleoclimate they are correlated with long term climatic changes with the aridity maximum at the k t boundary climatic changes were recorded via the change of salinity of waters interacting with the buried vertebrate remains

lithostratigraphy and depositional environments of the upper cretaceous djadokhta formation ulan nuur basin southern mongolia and its paleoclimatic implication abstract non marine upper cretaceous strata are widely distributed in the gobi basin of southern mongolia and record marked paleoenvironmental and paleoclimatic changes the climate in this region is considered to have changed from humid during the cenomanian to santonian to semi arid during the campanian and returned to humid during the early maastrichtian the change from humid to semi arid climate is well recorded in the djadokhta formation as former division in the ulan nuur basin of the central gobi basin in previous studies the djadokhta formation was formally regarded as being characterized by eolian deposits formed under a semi arid climate however the present study revealed that this formation comprises sub humid fluvial lithofacies in the lower part and semi arid eolian lithofacies in the upper part since the djadokhta formation was initially defined as a succession characterized by eolian lithofacies it is proposed here that the lower part showing fluvial lithofacies should be separated from the djadokhta formation and is newly named as the alagteeg formation the alagteeg formation is characterized by alternating beds of horizontally bedded sandstone and mudstone indicating sandy braided river flood plain and ephemeral lake environments under sub humid climate the djadokhta formation revised division is further subdivided into two parts the lower part is composed of large scale cross stratified sandstone in situ and reworked calcretes and thick mudstone lens suggesting desert environments of broad sand dune fields with few inter dune ephemeral river and pond deposits under semi arid climate on the other hand the upper part comprises structureless sandstone with mature in situ calcretes exotic pebbly sandstone and large sized burrows these lithofacies imply steppe environments with calcic soil development under semi arid climate this change from sub humid to semi arid climate during the campanian is recorded not only in the ulan nuur basin but also in other regions of southern mongolia as well as northern china hence the broad aridification in the mid latitudes of the asian interior during the campanian is inferred

source parameters of earthquakes in the strait of messina italy during this century abstract basic source parameters of earthquakes that have occurred in the seismogenic source region of the strait of messina southern italy are analyzed from seismological data and vertical ground displacements in particular faulting parameters associated with the 1908 ms 7 1 messina earthquake have been analyzed through inversion of coseismic displacements and available seismograms this normal faulting earthquake was located in the upper 15 km of the crust and had a source dislocation of 1 5 m on a fault plane striking n s and dipping 40 e this seismogenic region was quiescent before 1908 and later on this century but its surroundings i e the southern segment of calabrian arc is one of the most seismically active regions of italy with sequences of large earthquakes m 7 7 5 in 1638 1693 1783 and 1905 probably also associated with normal faulting as suggested by the regional tectonics during this century in the strait of messina small earthquakes occurred in 1952 ml 4 5 1961 ml 4 7 1975 ml 4 7 and in 1985 ml 4 1 this last being the first documented swarm sequence hypocenter distribution fault plane solutions seismic moments and stress drops have been computed from the data of a local seismic network consisting of up to eight stations the scaling law of the swarm events seems to show a departure from self similarity with earthquakes having a constant source radius of about 300 m

geochemical fingerprinting as a tool for repatriating poached dinosaur fossils in mongolia a case study for the nemegt locality gobi desert abstract over the past two decades illegal poaching of vertebrate fossils from the well known cretaceous exposures in mongolia s gobi desert has reached epidemic proportions following recent efforts led by the mongolian government to stem the flow of illegal fossils on the black market numerous important specimens have now been seized from private collectors a tandem objective has been to identify and document poached quarries in the field which is now allowing scientists to evaluate which areas and stratigraphic intervals are more intensively targeted and impoverished by poachers although illegal specimens are now being returned and becoming available for research the question of provenance still remains of both scientific and political concern to address this issue we investigated the geochemistry of the fossil rich baruungoyot and nemegt formations in the nemegt basin including both sediments and associated fossils using portable x ray fluorescence pxrf field data were collected using a stratigraphic criterion and are representative of several localities across the nemegt basin although the most complete datasets come from the nemegt and nearby khulsan localities secondarily pxrf data were acquired from specimens housed in ulaanbaatar including type recently described and poached specimens the final dataset includes approximately 700 pxrf readings we used a combination of multivariate analysis and data mining techniques to match known with unknown sample provenances and to determine the most informative elements from the geochemical array available for doing so results indicate that the chemical compositions of the baruungoyot and nemegt formations largely overlap with calcium being the most informative element for determining provenance from either bones or sediments however data arranged by geographic and stratigraphic occurrence thus reflecting different facies and palaeoecological settings resulted in more discriminant clusters the newly developed methodology represents the first systematic attempts to provide an innovative and rapidly implementable tool to support legal and scientific assumptions

faulting and earthquake triggering during the 1783 calabria seismic sequence summary between the 1783 february 5 and 1783 march 28 five earthquakes struck the southern part of calabria the main shock february 5 and the first aftershock february 6 devastated the region ene of the messina strait the greatest damage occurred along the foot of the aspromonte mountains south of san giorgio morgeto and along the tyrrhenian coast south of palmi a surface break about 18 km long with several feet of downthrow to the west formed along the cittanova santa cristina fault as a result of the main shock on february 7 a third large shock ruined villages at the foot of the serre mountains north of san giorgio morgeto morphological and structural evidence combined with a reassessment of observations made at the time of the earthquakes suggest that these three shocks were shallow 20 km and related to slip on the west dipping ne striking cittanova sant eufemia palmi scilla and serre normal faults respectively which juxtapose the basement of the aspromonte and serre mountains with the pleistocene deposits of the gioia tauro and mesima basins and border the palmi coastal high the three faults belong to an active rift that stretches from northern calabria to offshore the ionian coast of sicily the spatial coupling between the 1783 events is investigated by resolving changes of coulomb failure stress the main shock 1783 february 5 m 7 on the cittanova and sant eufemia faults increased that stress by several bars on the scilla fault triggering the 1783 february 6 earthquake m 6 5 the cumulative effect of these two shocks was to raise the coulomb stress by more than 1 bar on the sw part of the serre fault which was subsequently the site of the 1783 february 7 shock m 6 5 in turn the first three events increased the stress by about 1 bar on the ne part of this latter fault leading to the 1783 march 1 shock m 5 7 the gap between the 1783 february 7 and 1783 march 1 events may be related to the previous occurrence of an earthquake 124 yr before 1659 november 5 m 6 which had already released stress locally the occurrence of the last 1783 event 28 march is not as simply accounted for by coulomb modelling in part because it remains unclear which fault slipped and how deep this event was overall the 1783 sequence increased the coulomb failure stress by several bars south of the messina strait and north of the epicentral region of the 1693 se sicily catania noto earthquakes 125 yr later this same region was the site of the 1908 messina earthquake also a normal faulting event our study thus provides one convincing example in which coulomb stress modelling brings insight into the spatial dynamics of seismic sequences