tectonically induced diversion of the indus river west of the salt range pakistan abstract neogene and quaternary molasse deposition at the west end of the salt range in the foreland fold thrust belt of northern pakistan produced an unusually thick upper siwalik section near the indus river here siwalik sedimentary rocks coarsen upsection to 1500 m thick stacked channel conglomerate deposits with a distant provenance similar to deposits forming the bed load of the modern indus river the chisal algad an underfit stream separated from the indus river by a tectonically induced drainage divide contains a bed load clast assemblage resembling that of the indus river the indus channel migrated eastward abandoning the chisal algad and leaving high terrace deposits of indus gravels unconformably overlying tilted siwalik sedimentary rocks north of shakardarra uplift accompanying thrust faulting and transpression in the right slip kalabagh fault zone tilted a block measuring 15 km east west by 30 km north south the block has been incised by juvenile consequent drainage toward the indus river the indus river was diverted eastward in the last 0 5 ma and now occupies the lower part of the soan river system

gas condensate migration and oil fractionation in deltaic systems abstract the term evaporative fractionation is proposed to describe several phenomena involved in the secondary alteration of reservoired oil firstly it is suggested that oil is frequently partially vaporized in the reservoir secondly that gas bearing substantial portions of the oil in solution is conducted along faults to form independent gas condensate accumulations thirdly that residual oils formed in this fashion bear internal evidence of fractionation in addition to the conspicuous loss of light ends there is an increase in the content of light aromatic and naphthenic hydrocarbons relative to paraffins in the residual oil evaporative fractionation effects are recognized for the first time in the distillation and physical property data of us bureau of mines routine method oil analyses fractionation effects are postulated to be the cause of sigmoid as opposed to normal curvilinear aromatic profiles the effects of evaporative fractionation are widespread in oils throughout the united states they are evident in approximately 75 of oils in the gulf coast region and in a large proportion of the gas condensate accumulations the process is a major and apparently unrecognized means of petroleum alteration and of generation of gas condensates experimental evidence shows that partial vaporization results in enhanced levels of light aromatic hydrocarbons in residual oils oil samples were partially vaporized in excess methane at elevated pressure and temperature followed by removal of the vapour the gas chromatographic features of many gulf coast oils were reproduced various levels of light end depletion and enhancement of aromaticity were brought about

polyphase deformation in a fore arc back arc basin salin subbasin myanmar burma the salin subbasin of myanmar part of the larger central basin is a fore arc back arc basin couplet situated between an oblique subduction zone to the west and a major right lateral strike slip fault to the east surface and subsurface expressions of folds and faults suggest that the basin experienced north northwest directed extensional deformation in the miocene followed by east northeast directed pliocene pleistocene transpressional deformation resulting in a variety of structural styles including thrust faults oblique reverse faults strike slip faults and normal faults fault propagation folds cored by west dipping thrust faults in the basin center are located above steps in the top of basement surface most likely fault controlled unconformities at the base of and within the pliocene pleistocene synorogenic section indicate that the thrust faults were active during the pliocene pleistocene the southeastern region contains broad north northwest trending uplifts and east northeast striking normal faults associated with thickened miocene synorogenic deposits pliocene pleistocene sedimentary rocks lie unconformably above the miocene section and are folded above the uplifts reflecting pliocene pleistocene compression in the southern part of the basin miocene sedimentary rocks thicken dramatically over the 20 n uplift and the yedwet uplift suggesting that the north northwest striking faults that bound them represent pliocene pleistocene inversion of miocene normal faults during the miocene the burma plate acted as a fore arc sliver coupled with the india plate subducting obliquely underneath it and moved northward relative to asia along the sagaing fault normal faulting and local basin formation took place at this time when the northern part of the burma plate collided with eastern asia in the pliocene transpressional deformation predominated creating thrust and reverse faults positive flower structures and inverted basins

migration induced compositional changes in oils and condensates of a single field thirty one oils and condensates from the vermilion 39 field offshore louisiana u s gulf coast are examined using techniques of elemental isotopic and molecular geochemistry in an effort to determine the causes of compositional differences among them compositional variability in elemental concentration carbon isotope ratios and molecular distributions suggests that at least two sub groups occur in the sample set the sub groups are characterized by differences in n c 15 content relative to n c 15 pristane phytane ratio 13 c sulfur and nitrogen concentration and s n ratio although the separation into these two sub groups is superficially indicative of distinct sources and or variable levels of thermal maturity interpretation of the data set as a whole indicates that source influences maturity differences and biodegradation do not control observed variations in composition reliable source e g r c 27 29 sterane distribution and maturity e g 20s 20s 20r parameters provide clear evidence of a common source and constant maturity level for all 31 oils condensates the remaining geochemical differences including various molecular pristane phytane isotopic 13 c oil and elemental s n parameters correlate with the extent of migration fractionation that each sample has undergone as measured by the relative amount of n c 15 in each sample the migration fractionation process in the vermilion 39 field is facilitated by fault initiated pressure releases within reservoirs that originally contained full range crudes vertical migration of the released saturated hydrocarbon gases has led to a concentration of lighter components in the most fractionated samples this geochemical interpretation is supported by geologic data inasmuch as the extent of fractionation is least in the deepest samples and greatest in the shallowest samples the results presented here indicate the potential for misinterpretation of geochemical parameters previously considered to be influenced solely by source influence or thermal maturity

biomarkers of oligocene lacustrine source rocks beibuwan song hong basin junction offshore northern vietnam abstract highly oil prone source rocks containing sapropelic type i and mixed types i and iii kerogen are found in 233 m of the 500 m deep fully cored enreca 3 well drilled on bach long vi island located at the junction between the beibuwan and the song hong basins offshore northern vietnam the cored succession is made up entirely by oligocene deep lacustrine deposits the origin of the organic matter om in 62 samples is evaluated on the basis of gas chromatography mass spectrometry gc ms and gc ms ms om in 55 samples is sourced primarily from lacustrine organisms and contains abundant 4 methylsteranes tetracyclic polyprenoids tpp and lycopane and no markers for marine organic matter the proportion of triterpanes derived from angiosperms is low in most saturated fractions and only traces of gymnosperm diterpanes are detected in contrast all aromatic fractions have a high proportion of compounds having an origin from both gymnosperms and angiosperms very high concentrations of hopanoids in both fractions suggest significant bacterial alteration of the original om most samples have a high concentration of rare c31 diaromatic 8 14 secohopanes with a fluorene moiety low pristane phytane pr ph ratios indicate that anoxic suboxic bottom water conditions existed during om accumulation the presence of carotane gammacerane and traces of arylisoprenoids could indicate a stratified water column om in a few samples with lower than average hydrogen index hi is mainly of terrestrial origin with a higher proportion of c29 steranes diterpanes and oleanoids and lower concentrations of both saturated and aromatic hopanes higher pr ph a higher c34 isohopane ratio ihr34 and a lower homohopane index hhi indicate that this low hi om was originally deposited under more oxic conditions and subsequently transported to deeper water low sterane and hopane isomerization ratios show that no samples have reached the oil window some novel maturity parameters for immature lacustrine samples are proposed

late miocene pleistocene evolution of india eurasia convergence partitioning between the bhutan himalaya and the shillong plateau new evidences from foreland basin deposits along the dungsam chu section eastern bhutan the shillong plateau is a unique basement cored uplift in the foreland of the eastern himalaya that accommodates part of the india eurasia convergence since the late miocene it was uplifted in the late pliocene to 1600 m potentially inducing regional climatic perturbations by orographically condensing part of the indian summer monsoon ism precipitations along its southern flank as such the eastern himalaya shillong plateau ism is suited to investigate effects of tectonics climate and erosion in a mountain range broken foreland system this study focuses on a 2200 m thick sedimentary section of the siwalik group strategically located in the lee of the shillong plateau along the dungsam chu at the front of the eastern bhutan himalaya we have performed magnetostratigraphy constrained by vitrinite reflectance and detrital apatite fission track dating combined with sedimentological and palynological analyses we show that 1 the section was deposited between 7 and 1 ma in a marginal marine deltaic transitioning into continental environment after 5 ma 2 depositional environments and paleoclimate were humid with no major change during the depositional period indicating that the orographic effect of the shillong plateau had an unexpected limited impact on the paleoclimate of the bhutanese foothills and 3 the diminution of the flexural subsidence in the basin and or of the detrital input from the range is attributable to a slowdown of the displacement rates along the main boundary thrust in eastern bhutan during the latest miocene pleistocene in response to increasing partitioning of the india eurasia convergence into the active faults bounding the shillong plateau

geomorphometry and landform mapping what is a landform abstract starting from a concept of the land surface its definition and subdivision from digital elevation models dems is considered high resolution dems from active remote sensing form a new basis for geomorphological work which is moving on from consideration of whether data are accurate enough to how the surface of interest can be defined from an overabundance of data discussion of the operational definition and delimitation of specific landforms of varying degrees of difficulty from craters to mountains is followed by the applicability of fuzzy boundaries scaling usually allometric is shown to be compatible with the scale specificity of many landforms this is exemplified by glacial cirques and drumlins classification of a whole land surface is more difficult than extraction of specific landforms from it well dissected fluvial landscapes pose great challenges for areal analyses these are tackled by the delimitation of homogeneous elementary forms and or land elements in which slope position is considered the boundaries are mainly breaks in gradient or aspect but may also be in some type of curvature breaks in altitude are rare elementary forms or land elements are grouped together into functional regions landforms such as hill sheds it may often be useful to recognise fuzziness of membership or core and periphery of a surface object plains and etched or scoured surfaces defy most of these approaches and general geomorphometry remains the most widely applicable technique it has been applied mainly within arbitrary areas and to some extent to drainage basins but more experimentation with mountain ranges and other landforms or landform regions is needed geomorphological mapping is becoming more specialised and its legends are being simplified its incorporation into geographical information systems gis has required greater precision with definitions and the separation of thematic layers so that it is converging with specific geomorphometry and becoming more flexible and more applicable with a broader range of visualisation techniques

middle late miocene 10 ma formation of the main boundary thrust in the western himalaya three independent data sets from northwestern india and pakistan suggest initial displacement along 1000 km of the main boundary thrust prior to 10 ma at least 5 m y earlier than previously reported regionally extensive changes in the depositional characteristics and rates of the foreland basinfill between 11 and 9 5 ma are interpreted to reflect new hinterland loading due to the formation of the main boundary thrust sediment accumulation rates sandstone siltstone ratios and thickness and amalgamation of individual sandstone bodies all substantially increase after 11 ma in well dated stratigraphic sections from pakistan to nepal across the indo gangetic foreland basin in the himachal pradesh reentrant of northwestern india a newly discovered 8 7 ma conglomerate derived from the hanging wall of the main boundary thrust indicates that source area uplift and denudation must have occurred prior to 9 ma and probably prior to 10 ma assuming a gravelprogradationrateof3cm yr threeapatitefission trackages fromstructuresattheleadingedgeofthemainboundarythrustin the kohat region of northwest pakistan indicate that rapid cooling below 105 c1 2 m y earlier these data indicate that the main boundary thrust in the western himalaya formed synchronously along strike in the middle late miocene has a displacement rate of 10 mm yr and has a displacement history that is coeval with late displacement on the main central thrust

use of digital elevation models to understand and map glacial landforms the case of the canigou massif eastern pyrenees france abstract this paper presents an improved geomorphological methodology that uses remotely sensed data a geographical information system and a brief field campaign to allow rapid yet precise mapping as well as interpretation and analysis of glacial earth surface morphology in high mountain areas the study area consists of the quaternary glaciated part of the coumelade valley canigou massif eastern pyrenees france which ranges between 1450 and 2731 m a s l a topographical map derived digital elevation model was used for analyzing glacial landforms by extracting the slope gradient valley profiles and the slope aspect the results were gradually refined from the interpretations of aerial photograph and the field investigation glacial landforms are present above 1500 m a s l and include glacial and nivation cirques cirque and latero frontal moraines 7 7 106 m and micro scale landforms such as chattermarks crescent grooves and polished surfaces the geomorphological investigation reveals that the quaternary glaciation of the coumelade valley remained limited resulting in a low denudation rate of 0 011 mm yr 1 over the last glacial cycle

the oleananes origin maturation and limits of occurence in southern nigeria sedimentary basins oleananes occur within well defined age and paleogeographic boundaries in the sedimentary province of southern nigeria thus signifying that the biomarkers may be analogous to index fossils in anambra syncline lower benue trough the biomarkers are found in rocks which are as old as late upper cretaceous in tertiary niger delta the concentration composition and distribution of the oleananes in rocks and oils are determined mainly by palaeodepositional environment and thermal history and are independent of age and geographical location of specific samples oleanane content varies with increasing burial depth with peak concentration coinciding within rm range 0 4 0 6 implying early generation of hydrocarbons from the basin s typically resin rich kerogens it is evident that the oleanane content parameter is superior to the hopane and sterane isomerisation indices for monitoring thermal maturation in the delta and for differentiating paralic from paralic marine source facies as well as early from late generated oils

first global positioning system results in northern myanmar constant and localized slip rate along the sagaing fault we present the first recorded global positioning system gps data from myanmar measured at the northern tip of the sagaing fault this area is in a very complex geodynamic context where rigid and semirigid plates interact the 12 gps sites measured in 2005 and 2008 in northern myanmar show that the slip rate is 18 mm yr and is localized along a single active narrow fault trace 20 km wide the same rate was previously demonstrated and remeasured 500 km southward in central myanmar despite the geodynamic regional complexity induced by interaction between the sunda and india plates the burma microplate and the highly deformable eastern himalayan syntaxis the slip rate remains surprisingly constant along this fault however the modeled locking depth varies from 20 km in central myanmar to 5 km in the north

drainage density slope angle and relative basin position in japanese bare lands from high resolution dems abstract relationships between drainage density and slope angle for three bare lands in japan were analyzed with special attention to channels at early erosion stages and channels in a badland type terrain two of the bare lands were caused by volcanic eruptions 1 or 30 40 years ago and the other one is a landslide scar formed more than 100 years ago raster digital elevation models dems with a 1 m resolution and ortho aerial photos were generated using digital photogrammetry to enable detailed stream net extraction and topographic analyses data for drainage density slope angle and relative height for 88 subwatersheds were obtained from the dems and derived stream nets the relationship between drainage density and slope angle for each subwatershed can be divided into two types downward sloping and convex upward although previous studies suggested that drainage density positively correlates with slope angle if overland flow is dominant this correlation seldom occurs in the study areas the two types of drainage density slope angle relationships correspond to differing channelization stages that reflect the extension and integration of existing channels as well as the formation of new low order streams in response to base level lowering the location of subwatersheds within each study area seems to play a major role in determining the stages of channel development and in turn the types of drainage density slope angle relationships

δ2 triterpenes early intermediates in the diagenesis of terrigenous triterpenoids a series of 2 triterpenoids oleana 2 12 diene oleana 2 13 18 diene oleana 2 18 diene ursa 2 12 diene and taraxera 2 14 diene has been identified in holocene buried mangrove sediments florida usa by comparison of the mass spectra of and by co injections with authentic standards in the oligocene brandon lignite vermont usa oleana 2 12 diene and oleana 2 13 18 diene were also identified along with two a ring contracted amyrin derivatives by comparison with the sedimentary occurrence of related analogues of oxyallobetulin and betulin and the demonstrated diagenetic formation of lup 2 ene from lupan 3 one these novel terrigenous biological markers are considered diagenetic products formed by dehydration of precursor molecules such as and amyrin and taraxerol the identification of these early intermediates brings us one step closer to the full understanding of the diagenetic fate of terrigenous triterpenoids

a review of the occurrences and causes of migration contamination in crude oil abstract migration contamination occurs when a migrating or trapped crude oil functions as a solvent dissolving molecular components from the syndepositional organic matter of the migration conduit and or the reservoir rock this review documents the causes and worldwide occurrences of migration contamination and suggests methods of identifying the signatures of this phenomenon within the molecular and isotopic composition of crude oils instances of migration contamination have been identified in oils of australia asia africa and north america and are best identified by the presence of molecular and or isotopic imbalances in the oil such imbalances are most apparent when co occurring molecular suites are incompatible with one another particularly in terms of thermal maturity occurrences of migration contamination in oils of the us gulf of mexico documented by molecular maturity imbalances such as the presence of unsaturated hydrocarbons known to be unstable at petroleum generation temperatures provide the best examples of this phenomenon an attempt is made to quantify the extent and impact of this process in the vermilion 14 field offshore louisiana in the us gulf of mexico here molecular maturity markers in the migrated fluid and in the syndepositional organic matter of the reservoir rocks are compared and the proportion of contamination in each reservoired fluid is estimated examples such as this may assist in explaining maturity anomalies observed in several oils worldwide particularly in tertiary reservoired oils that have migrated through and are trapped in thermally immature sediments it is suggested that the low molecular maturity ratios often observed in tertiary reservoired oils and attributed to unusually high heating rates may be caused at least in part by migration contamination

geological evidence against large scale pre holocene offsets along the karakoram fault implications for the limited extrusion of the tibetan plateau two end member models proposed to accommodate the convergence between india and asia north of the himalaya are 1 homogeneous crustal thickening of the tibetan plateau and 2 continental escape or extrusion of tibet and southeast asia away from the indenting indian plate foremost among the arguments supporting the latter would be large scale 1000 km offsets and high present day slip rates along the major strike slip faults bounding the postulated extruding crust notably the altyn tagh fault along the northern margin of tibet and the karakoram fault along the sw margin satellite photographic interpretation and field mapping in the karakoram mountains in pakistan the nubra siachen area of north ladakh and the pamirs in xinjiang show that although the karakoram fault is extremely active today geological offsets along the right lateral fault are probably less than 120 km the 21 0 5 ma baltoro monzogranite leucogranite batholith has been rotated clockwise about a vertical axis 35 40 into nw se alignment parallel with the karakoram fault east of the siachen glacier with a maximum offset of 90 km across the fault the bangong shyok suture zone similarly has a dextral offset of 85 km the course of the indus river which was antecedent to the rise of the ladakh karakoram and himalayan ranges has been offset dextrally by 120 km south of pangong lake if present day slip rates approximately 32 mm yr avouac and tapponnier 1993 are correct only 4 ma are required to obtain a 120 km offset there is no geological evidence for any larger scale pre holocene offsets and it is suggested that the karakoram fault cannot have accommodated major eastward lateral motion of tibetan crust the fault has also exerted little or no influence on surface topographic uplift cutting obliquely across the highest peaks of the karakoram dextral motion along the central part of the karakoram fault has been transferred in the north to the rangkul murghab and karasu transpressional faults in the central pamir north of tashkurgan the karakoram fault shows mainly normal motion around the kongur and mustagh ata gneiss domes metamorphic core complexes and the extensional muji graben minor dextral displacement has occurred along the shiquanhe fault but this motion cannot be linked to the jiale fault of east tibet the southern end of the karakoram fault merges with the indus yarlung suture zone near mount kailas and does not cut across the himalaya the lack of large scale geological offsets along the karakoram fault together with its very recent initiation 5 or 4 ma suggests that it is related to the pliocene quaternary northward indentation of the pamir and not to any long term extrusion of tibetan crust following the indian collision

digital terrain modelling a review of hydrological geomorphological and biological applications the topography of a catchment has a major impact on the hydrological geomorphological and biological processes active in the landscape the spatial distribution of topographic attributes can often be used as an indirect measure of the spatial variability of these processes and allows them to be mapped using relatively simple techniques many geographic information systems are being developed that store topographic information as the primary data for analysing water resource and biological problems furthermore topography can be used to develop more physically realistic structures for hydrologic and water quality models that directly account for the impact of topography on the hydrology digital elevation models are the primary data used in the analysis of catchment topography we describe elevation data sources digital elevation model structures and the analysis of digital elevation data for hydrological geomorphological and biological applications some hydrologic models that make use of digital representations of topography are also considered

the petroleum geochemistry of canadian beaufort tertiary non marine oils abstract molecular isotopic and elemental data for a set of 28 paleogene and 3 cretaceous oils from the mackenzie delta and offshore canadian beaufort sea have been evaluated the depositional environment and organic matter characteristics of the source units for these oils have been predicted the paleogene oils of the canadian beaufort are molecularly distinctive and clearly contain a major land plant component oleanane and the 17 h and 17 h 24 28 bisnorlupanes are present as well as the following compound types 24 norlupanes and possibly higher homologues de a lupane noroleanenes norursene dehydroabietane 28 30 bisnorhopanes several molecular and isotopic characteristics are useful in assessing and ordering the extent of biodegradation and thermal maturation of these oils the cretaceous oils are separately sourced from the paleogene oils the latter oils comprise two distinct land plant derived genetic families distinguished by the presence absence of 24 28 bisnorlupanes 24 norursene 24 norlupane and 24 noroleanenes the kugmallit richards family contains each of these compound types and is considered to originate from the eocene richards formation in contrast lupanoids and noroleanenes are absent in oils of the reindeer moose channel family the occurrence of 28 30 bisnorhopane and or oleanane in these oils suggests a paleocene origin although these source rock predictions are supported by the available data they must be considered speculative until detailed molecular isotopic and elemental compositional data are available regionally for potential source rocks of the eocene and paleocene source units in the canadian beaufort

thrusting and gravel progradation in foreland basins a test of post thrusting gravel dispersal the use of gravels as syntectonic indicators of thrusting has recently been questioned by foreland basin models that assign gravels to a post thrusting interval of progradation except in very proximal areas on the basis of precise temporal control provided by magnetostratigraphically dated sections the history of gravel progradation after a major thrusting and uplift event in the northwestern himalaya is shown to be a virtually syntectonic phenomenon despite considerable crustal subsidence driven by a thick skinned thrust gravels prograded approximately 70 km during a 1 5 m y long thrusting event by 3 m y after the start of thrusting gravels extended more than 110 km into the basin although delayed gravel progradation appears appropriate for many rocky mountain foreland basins it is clearly not valid for the himalaya the authors attribute the difference in depositional response between these basins to difference in the quantity of sediment supplied to them sediment starved vs overfilled the availability of resistates in the source area and the size of the antecedent drainage

productivity control on oil shale formation mae sot basin thailand abstract neogene oil shales from the freshwater lacustrine intermontane mae sot basin western thailand are examined in order to define a oil source rock potential b variations in molecular and isotopic geochemical characteristics and c the influence on source potential of organic matter productivity and preservation twelve samples spanning 7 m of section were examined using conventional isotopic molecular and organic petrographic methods of geochemical analysis temporal resolution is 2700 yr per sample because thermal maturity differences and fluid migration within the sample set are absent and organic matter type input variation is either minor or absent based on visual kerogen analysis we propose that organic matter differences among the samples are caused by variability in surface water productivity all samples are excellent potential source rocks vr 0 4 0 5 ro containing types i and ii organic matter modified van krevelen plot determination consisting of almost 100 fluorescent amorphous kerogen visual kerogen determination numerous diagnostic molecular markers and characteristics are present including perhydro carotene dammaranes norsterane s and novel distributions of tricyclic terpanes stable carbon isotope ratios of kerogens and extract fractions range over 5 and co vary with hydrogen index this covariance is attributed to temporal increases in surface water productivity leading to co2 limiting conditions and consequent increase in 13c of the organic matter in the photic zone during times of elevated productivity increased amounts of 13c enriched organic matter reached the water sediment interface thus times of greater productivity are accompanied by higher 13c and hydrogen index values with 13c related to productivity under co2 limiting conditions and hi related to the relative amount of the water column that was anoxic during deposition our findings suggest that in petroleum geochemical studies involving lacustrine source rocks 13c values must be used with caution as oil oil and oil source rock correlation parameters

the central myanmar burma oil family composition and implications for source abstract geochemical characteristics of 31 miocene through eocene oils seeps an eocene coal and an eocene resin from the central myanmar burma basin system are examined the oils seeps vary widely in api gravity 8 52 sulfur concentration 26 3550 ppm 13 c 27 6 to 23 4 and molecular composition this variability is caused by varying amounts of biodegradation superimposed upon a single genetic oil family and the difference between aliphatic and aromatic hydrocarbon carbon isotope ratios i e 13 c arom 13 c aliph provides a useful gauge of the extent of biodegradation the projected geochemical characteristics of unaltered central myanmar oils are as follows a api gravity 35 37 b s 0 05 0 10 c 13 c aliph 27 8 to 27 6 d 24 ethylcholestanes are the dominant steranes and e 20s 24 ethyldiacholestane various bicadinanes and oleanane are present the ratio of 18 h 22 29 30 trisnorneohopane to 17 h 22 29 30 trisnorhopane t s t m is postulated as a maturity parameter and on this basis relative bicadinane concentration increases and the trans trans trans cis cis trans bicadinane ratio decreases with increasing thermal maturity in this oil set geologic arguments suggest a deep paleogene source for these oils two geochemical arguments that support this inference are a the occurrence of saturated and unsaturated c 15 and c 30 cadinane monomers and dimers in pyrolyzates of an eocene resin and the kerogen from an eocene coal and b identical compound specific carbon isotope ratios for selected isoprenoids and n alkanes in a typical central myanmar oil and the hydrous pyrolyzate expelled from an eocene coal we propose an eocene resinous shale coal source for these oils with the oldest eocene reservoirs filling first and the youngest miocene reservoirs filling last consistent with the observation that the least mature oils are present in the oldest reservoirs according to this model surface seepage and near surface oil could result from subsurface traps that are filled to spillpoint

occurrence of polycadinene in fossil and recent resins abstract dammars produced by dipterocarpaceae growing in southeast asia are partly composed of a macromolecule with a polycadinene structure this polymer is the precursor of many specific compounds encountered in crude oils and sediment extracts from south asia until recently there was no evidence for a more widespread geographical occurrence of this resinous polymer using different pyrolysis methods it is shown that the polymers present in a resinite from utah usa and in resins contained in resin canals of eocene fossil fruits from germany and england are also polycadinenes the fossil fruits were undoubtedly produced by ancient representatives of mastixioid cornaceae a group of plants which was widespread in the tertiary of europe and north america and which is not related to dipterocarpaceae these findings extend the known occurrence and origin of the sesquiterpenoid type resin polymer it is to be expected that catagenetic products of these resin polymers should be present in oils coals and sediment extracts from areas outside southeast asia

biodegradation of tar sand bitumens from the ardmore and anadarko basins carter county oklahoma abstract a series of tar sand bitumens collected from a single shallow well in the ardmore basin carter county oklahoma has been characterized by various geochemical techniques particular emphasis has been placed on determination of variations in biomarker distributions both hydrocarbons and porphyrins as a function of biodegradation the tar sand bitumens have been severely biodegraded and most of the n alkanes low molecular weight cycloalkanes isoprenoid alkanes c27 c29 steranes light aromatics and sulfur compounds have been removed in addition the hopane distributions have been altered to differing degress with the pseudohomolugoues above c30decreasing in concentration prior to the c20 21 the triaromatic steroid hydrocarbons were also altered with preferential removal of 20r epimers c20 21 and c27 28 diasterane and c30 sterane distributions appear to be relatively unaffected by biodegradation the high resistance of tricyclic terpanes the c24 tetracyclic terpane and monoaromatic steroid hydrocarbons to biodegradation indicate that the distributions of these compounds are well suited to serve as correlation parameters in heavily altered samples it was also observed in this study that the main ring structure of the porphyrin molecule was not affected by these very high levels of biodegradation previously hypothesized changes in porphyrin structure due to biodegradation have included n alkyl side chain cleavage and possible conversion from dpep to etio type porphyrins an investigation has also been made with an active seep collected from sulphur in the anadarko basin oklahoma and the results show that the relative rate of biodegradation of various classes of biomarkers differs between these two locations although it was proposed that the original oil responsible for these two seeps is derived from the same source rock formation

automated classifications of topography from dems by an unsupervised nested means algorithm and a three part geometric signature abstract an iterative procedure that implements the classification of continuous topography as a problem in digital image processing automatically divides an area into categories of surface form three taxonomic criteria slope gradient local convexity and surface texture are calculated from a square grid digital elevation model dem the sequence of programmed operations combines twofold partitioned maps of the three variables converted to greyscale images using the mean of each variable as the dividing threshold to subdivide increasingly subtle topography grid cells sloping at less than mean gradient of the input dem are classified by designating mean values of successively lower sloping subsets of the study area nested means as taxonomic thresholds thereby increasing the number of output categories from the minimum 8 to 12 or 16 program output is exemplified by 16 topographic types for the world at 1 km spatial resolution srtm30 data the japanese islands at 270 m and part of hokkaido at 55 m because the procedure is unsupervised and reflects frequency distributions of the input variables rather than pre set criteria the resulting classes are undefined and must be calibrated empirically by subsequent analysis maps of the example classifications reflect physiographic regions geological structure and landform as well as slope materials and processes fine textured terrain categories tend to correlate with erosional topography or older surfaces coarse textured classes with areas of little dissection in japan the resulting classes approximate landform types mapped from airphoto analysis while in the americas they create map patterns resembling hammond s terrain types or surface form classes srtm30 output for the united states compares favorably with fenneman s physical divisions experiments are suggested for further developing the method the arc info aml and the map of terrain classes for the world are available as online downloads

river systems and their sediment flux indo gangetic plains northern bihar india river systems of part of the himalayan foreland northern bihar plains india are described in terms of their channel morphology hydrology and suspended sediment characteristics a simple classification of the river systems based mainly on the source area characteristics is proposed i mountain fed ii foothills fed iii plains fed and iv mixed fed rivers distinct differences are noted between these classes of river systems most rivers show evidence of channel movement mainly by avulsion but cut offs also occur locally the mountain fed rivers are characterized by very high discharge and low suspended sediment concentration and the plains fed rivers have relatively low discharge and high suspended sediment concentration the foothill fed rivers have moderate values of discharge and suspended sediment concentration the mountain fed rivers have built megafans of large extent whereas the foothills fed and plains fed rivers have formed muddy interfan areas semi quantitative estimates of water and sediment flux suggest that about 99 9 of the mass transfer into the plains is water with the remaining 0 1 being sediment and that 10 s of the latter 0 01 of the total is retained in the basin the remainder being transferred to the bengal fan

exotic conglomerates of the neogene siwalik succession and their implications for the tectonic and topographic evolution of the western himalaya

organic petrology of subbituminous carbonaceous shale samples from chalāw kabul province afghanistan considerations for paleoenvironment and energy resource potential abstract neogene subbituminous carbonaceous shale deposits from chal w afghanistan were investigated through organic petrology techniques and standard coal analyses to determine paleoenvironment and potential for resource utilization the chal w deposit approximately 30 km southeast of kabul currently is exploited for brick making and domestic heating and cooking three multiple bench channel samples of the mined bed at chal w were collected and evaluated the presence of significant huminite ranging from 0 2 to 59 0 vol mineral inclusive basis is suggestive of a terrestrial lignin rich precursor plant material measured reflectance values of 0 38 0 55 indicate subbituminous rank this rank suggests burial depths of approximately 1500 m and maximum temperatures of approximately 50 c structured liptinite macerals generally are absent except for some fluorescing morphologies interpreted to be poorly preserved root cork suberinite sponge spicule bioliths including gemmoscleres and megascleres are common these petrographic observations in addition to high mineral matter content 33 to 95 vol medium to high sulfur content 2 1 11 5 wt dry basis db and the presence of common gastropod shell fragments and an aragonite needle chalk bed are consistent with but not directly indicative of a marginal marine or estuarine mangrove depositional environment however additional data are necessary to confirm this hypothesis and deposition in a freshwater environment cannot be ruled out at this time commercial scale development and utilization of the chal w deposit as a thermal fuel resource may be possible using a fluidized bed combustion system which could accept the low quality mine product currently produced samples examined herein contain high ash yield 45 90 wt db high total moisture content 17 39 wt low calorific value 980 6860 btu lb m mmf and have poor agglomerating properties fsi 0 consistent with fuels utilized in fluidized bed combustors however delineation of the extent of the deposit through field investigation will be necessary to make a quantified resource estimate for mine planning

combined effects of eurasia sunda oblique convergence and east tibetan crustal flow on the active tectonics of burma it is widely accepted that deformation of the india sunda plate is the result of partitioned hyper oblique convergence presently sub meridian dextral strike slip faulting accommodates this india sunda motion in a buffer zone the burma platelet this wide dextral strike slip shear zone is complicated by the side effect of the tibet plateau collapse that can be described in term of crustal flow and gravity tectonics the loss of potential energy related to this plateau collapse affects most of the burmese platelet particularly in its northernmost part interaction of these two distinct geodynamic processes is recorded in the gps based regional strain field the analysis of seismic focal mechanism but also from direct geologic observations both onshore and offshore myanmar and bangladesh we propose the apparent e w shortening component of this so called partitioned hyper oblique subduction is only the effect of regional gravitational forces related to the tibet plateau collapse whereas the ns strike slip faulting accommodates the india sunda motion

tertiary oils from upper assam basin india a geochemical study using terrigenous biomarkers abstract the upper assam basin in northeast india is a tertiary sub basin of the assam arakan basin hydrocarbons are present in the langpar formation upper palaeocene lakadong member of the sylhet formation lower eocene and the barail oligocene tipam lower miocene and girujan middle miocene formations in the basin a detailed study to understand the nature and origin of the oils from different stratigraphic horizons using terrigenous and other biomarkers has been carried out further the variation in maturities of oils occurring in different stratigraphic horizons has also been studied the study shows that rearranged oleananes oleananes and bicadinanes are present in these oils implying land plant input to their source rocks the oils have been classified into different groups using ratios of rearranged oleananes oleananes bicadinanes and steranes indicating presence of multiple source rocks in the basin with subtle variation in characteristics maturity studies show that oils from younger horizons barail tipam and girujan are more mature than oils from older horizons langpar and lakadong there is an apparent mismatch in maturity of oils as measured by different biomarker maturity parameters this is due to the mixing of two different charges of oils having different maturities and generated from two different source rock kitchens in the same reservoir principal component analysis pca of biomarker data has also been able to classify the oils into various groups a new parameter has been developed using ratios of rearranged oleananes for determining maturity of these oils

assessing regional geodiversity the iberian peninsula geodiversity is a landscape characteristic related to the heterogeneity of the physical properties of the earth surface in this work we quantify and compare geodiversity in several geodynamic zones of the iberian peninsula for this purpose we have developed a geographic information system gis procedure to carry out a regional terrain classification based on geodiversity factors a classification process helped to produce a morphometric map 10 classes a morphoclimatic map five classes and a geological map 15 classes these three maps were combined using an overlay operation union to obtain the final terrain classification 419 classes which was then applied to calculate diversity landscape indices the latter were calculated using common landscape diversity indices patch richness density shannon s diversity index shannon s evenness index simpson s diversity index and simpson s evenness index provided by fragstats free software these indices were calculated for the whole landscape of the main iberian geological regions thus revealing a close relationship between some index values and the geological and geomorphological characteristics the highest diversity values are associated with alpine collisional orogens and reactivated chains of the precambrian palaeozoic massif intraplate orogen with sedimentary cover characterized by extensive planation surfaces have lower values mesozoic areas with no significant tectonic deformation and cenozoic basins are characterized by the lowest diversity values amongst the latter the major diversity is associated with the most dissected basins which also present higher morphoclimatic variety though depending on the chosen scale and the landscape classification criteria these indices provide an objective assessment of the regional geodiversity of iberia copyright 2009 john wiley sons ltd

automatic relief classification versus expert and field based landform classification for the medium altitude mountain range the sudetes sw poland abstract the main purpose of the study is to compare the results of automatic classification of landforms performed as unsupervised classification and manual expert morphographic landform classification derived from field mapping and recognition of long term trends in landform evolution two test areas in the sudetes mountains sw poland were selected each representing a different type of relief the jelenia gora basin is an example of denudational hilly granite topography with inselbergs other residual hills and basins whereas the northern part of the bystrzyckie mountains is a faulted plateau underlain by sedimentary and metamorphic rocks the setup of the classification involved a dem derived from digitalization of 1 25 000 maps a filter mask of 20 20 pixels 500 500 m k median cluster analysis and consideration of four dimensions relative height slope combined curvature and aspect we used a statistical criterion to decide the level of classification i e the number of homogeneous groups returned output maps show the results of classification into five jelenia gora basin or six groups bystrzyckie mountains later confronted with nine group classification in both areas automatic classification for k 5 6 performed well and the principal features of relief are well captured despite very different landform patterns and long term geomorphic histories slope and curvature are the main variables to differentiate individual terrain units landforms with an additional role of aspect in the faulted and tilted plateau for k 6 aspect becomes the main variable in the hilly relief and the pattern of terrain units becomes more fragmented adversely impacting on the clarity of interpretation while surfaces in the faulted plateau setting are further subdivided according to slope and curvature the match between expert maps and the results of automatic classification varies depending on the landforms considered while certain landforms are clearly associated with one particular group yielded by automatic classification others fall into a number of groups and do not have distinctive signatures despite different origins

structure and kinematics of the indo burmese wedge recent and fast growth of the outer wedge 1 the northern sunda subduction zone offshore burma and the associated indo burmese wedge mark the active eastern boundary of the burma platelet jammed between the india plate and the sunda plate the aim of this paper is to provide a structural and kinematics analysis of the indo burmese wedge based on seismic reflection geodetic and geological field data we found out that the indo burmese wedge is the place of diffuse strain partitioning right lateral shearing in the innermost part and e w shortening in the outermost part in the outer wedge thick skinned deformation overprints thin skinned deformation it can be explained by the required preservation of the critical taper after the fast westward propagation of the outer wedge above a very efficient clayey decollement layer the thick skinned deformation is here characterized by major right lateral strike slip faults the kaladan fault and the chittagong coastal fault and yet a typical internal deformation of the indo burmese wedge we suggest that the westward migration of internal right lateral shear deformation allows preservation of the strain partitioning ratios between internal n s trending right lateral shearing and external e w shortening some seismic lines show that the outer wedge deformation is not older than 2 ma its propagation could have been enhanced by the large amount of sediments filling up the sylhet flexural basin formed after the pliocene tectonic uplift of the shillong plateau

sequential late cenozoic structural disruption of the northern himalayan foredeep chronologies for the siwalik molasse and intermontane basins along the southern margin of the himalaya and hindu kush ranges constrain the timing and pattern of facies migration and structural disruption of the indo gangetic foredeep this synthesis indicates that quiescent intervals are punctuated by pulses of rapid deformation as thrusting migrates in a stepwise fashion across the foredeep

geomorphometry based detection of enhanced erosional signal in polygenetic medium altitude mountain relief and its tectonic interpretation the sudetes central europe abstract we explore the assumption that uplift drives erosion and hence more dissected eroded terrains may indicate areas subject to more intense uplift than others especially if other factors such as elevation and geology can be demonstrated as inconsistent with the spatial pattern of dissection geomorphometry and statistics are employed to recognize the enhanced erosional signal within a medium altitude mountain terrain of the sudetes in central europe considered as a representative for moderately uplifted areas of complex bedrock diversity this signal is understood as a meso scale reflection of relief properties whereas the recognition of homogeneous terrain units different in terms of strength of erosional signal is carried out by means of multi criteria terrain classification involving principal component analysis and k means grouping four groups covering 45 of the area have been identified they were quantitatively compared with independent variables of altitude lithology structural units and rock strength and also assessed in relation to rainfall pattern it is concluded that their dependence on altitude and geology is only partial then three types of dissected terrain are distinguished and interpreted in terms of uplift intensity rock strength as a factor modulating erosional response to uplift and timescale the spatial distribution of these types of terrain indicates several isolated hot spots of erosional dissection on predominantly strong rocks linked by less elevated areas underlain by rocks of variable strength the former are considered as having longer history of uplift and dissection dated back to the late palaeogene whereas the latter record more recent history of endo exogenic interactions possibly since the late miocene the presence of canyon like valleys incised into planar or gently sloping relief may indicate the most recent pulse of relief rejuvenation the procedure proposed in the paper is suitable to be used in various settings given that good quality topographic data are available

steroidal hydrocarbons of the kishenehn formation northwest montana abstract the oligocene kishenehn formation of northwest montana and southeast british columbia consists of fluvial and lacustrine sediments marlstones lignites and oil shales deposited in an elongate intermontane half graben the petroleum source rock potential and steroidal hydrocarbon distribution of selected shales of the kishenehn formation were examined several steroidal hydrocarbon series were documented including 4 desmethylsteranes 4 methylsteranes sterenes diasterenes spirosterenes c ring monoaromatic steroids and b ring monoaromatic anthrasteroids non steroid hydrocarbons present include hopenes hopanes moretanes perylene botrycoccane a series of alkylcyclohexanes and a fused ring aromatic tentatively identified as a tetrahydrochrysene source rock analysis indicates that the kishenehn formation possesses excellent petroleum source potential conventional thermal maturity parameters vitrinite reflectance and rock eval tmax values as well as maturity parameters derived from molecular parameers n alkane steroid and hopanoid distributions suggest that much of the kishenehn formation is currently undergoing organic diagenesis typical molecular indicators of thermal immaturity include the occurrence of high relative amounts of a 5 h desmethylsteranes b 14 h b ring monoaromatic anthrasteroids and c 4 ch3 methylsteranes a near shore freshwater lacustrine depositional environment is indicated with some input of terrigenous organic matter high cpi c23 c31 n alkanes and relatively high ethylcholestane content while the presence of 4 methylsteroids and botryococcane indicate significant contributions from dinoflagellates andbotryococcus braunii the occurrence in the kishenehn formation of a diverse selection of 4 methyl and 4 desmethyl aliphatic and aromatic steroids provides a unique opportunity to monitor co variance of molecular maturity indicators in sediments depositedunder relatively constant depositional conditions

tertiary tectonics and sedimentation in the salin fore arc basin myanmar salin basin of central myanmar is a tertiary fore arc basin that extends over 10 000 mi sup 2 and contains 30 000 ft of siliciclastic rocks in the western salin basin tertiary deltaic and fluvial formations contain thousands of feet of lithic sandstones that alternate with transgressive shallow marine shales facies and paleocurrent studies indicate deposition by north to south prograding tidal deltas and associated fluvial systems in a semi restricted basin presence of serpentinite and volcanic clasts in tertiary sandstones may imply that the basin was bounded to the east by the volcanic arc and to the west by a fore arc accretionary ridge throughout much of the cenozoic salin basin is currently defined by a regional north south trending syncline with uplifts along the eastern and western margins elongate folds along the eastern basin margin verge to the east and lie above the reverse faults that dip west much of myanmar s present hydrocarbon production is from these structures analogous structures occur along the western margin but verge to the west and are associated with numerous hydrocarbon seeps and hand dug wells these basin bounding structures are the result of fault propagation folding in the western salin basin major detachments occur within the shaly tabyin and laungshe formations fault ramps propagatedmore through steep forelimbs on the western sides of the folds resulting in highly asymmetric footwall synclines stratigraphic and apatite fission track data are consistent with dominantly plio pleistocene uplift with limited uplift beginning approximately 10 ma paleostress analysis of fault slickenside data indicates that fold and thrust structures formed during regional east west compression and are not related in any simple way to regional transpression as suggested by plate kinematics less

origin of petroleum in bangladesh fewer than 70 exploration wells have been drilled in bangladesh 207 000 km2 mostly in the eastern onshore and offshore areas making it one of the least explored countries in the world tectonic developments have controlled the accommodation space available for sediment deposition since the early cretaceous collision between the indian plate and eurasia to the north of bangladesh and between the indian plate and the burma platelet on the east provided favorable conditions for development of oligocene miocene source rocks and miocene reservoir sands in eastern bangladesh the resulting jenam bhuban boka bil petroleum system is the most active system identified to date and is dominant in eastern bangladesh hydrocarbons likely also have been generated from the organic rich shales of the miocene bhuban formation the jenam bhuban boka bil petroleum system alone is responsible for the generation of more than 16 tcf of gas in place discovered to date mostly in the surma basin of the chittagong tripura fold belt several other petroleum systems have been postulated in bangladesh together the best technical estimate of the total resource base is about 61 tcf including reserves within the discovered fields anticipated field growth and new field discoveries with the exception of small bacterial contributions in some surface seep gases and two subsurface accumulations the gases of bangladesh are thermogenic modeling results indicate that the gases and associated condensates are sourced at peak generation depths of at least 6 km many of the gas accumulations are associated with retrograde condensates whose compositions are defined by two distinct source facies and by the solution exsolution effects of vertical migration most of the condensates possess molecular signatures that indicate a major hydrogen rich angiospermous flowering land plant contribution to the organic matter of their source rock s the carbon isotope ratios of the methane in the gases and the isotopic and molecular characteristics of the associated condensates indicate a distinct source facies for petroleums of the northern surma basin relative to those in the south these isotopic and molecular results when interpreted in light of the geological framework and our basin models suggest that the oligocene jenam formation is the major contributor north of 24 4 degreesn and that the miocene bhuban formation is the major contributor to the south

bicadinanes and other terrestrial terpenoids in immature oligocene sedimentary rocks and a related oil from the surma basin n e bangladesh abstract the aliphatic fractions and one aromatic fraction of outcropping oligocene rocks from the ne surma basin of bangladesh were studied by gc ms and compared with their subsurface equivalents and one oil sylhet from boreholes further south in the basin terrestrial biomarkers frequently encountered in these rocks whose biomass is dominantly woody include the triterpanes oleanane and bicadinane several tetracyclic terpanes and the sesquiterpenoids cadinane and cadalene the bicadinanes and their aromatized counterparts are found as major triterpenoid components only in the upper jenam formation where the richest horizons are interpreted to contain locally derived concentrations of dammar type resin excluded from dipterocarpaceae or similar tropical angiosperm trees vitrinite reflectance and geochemical maturity parameters indicate pre oil window maturity for the upper jenam outcrop allowing a temperature of less than about 90 c to be estimated for the formation of bicadinanes from resinous polymer cis cis trans bicadinane which is abundant in sylhet oil was not positively identified in any of the rock extracts although the distribution of bicadinanes is otherwise very similar

the first stages of erosion by ice sheets evidence from central europe abstract in almost all former and presently glaciated areas of the world glaciers have modified or even transformed pre glacial terrain during the many cold stages of the pleistocene in consequence the early stages in the development of glacial landscapes have been overprinted or erased by later phases of erosion the sudetes in central europe provide exceptional opportunities to examine the inception of glacial erosion evidence of a long geomorphic evolution before glaciation with the development of etch surfaces deep weathering covers and the preservation of neogene kaolinitic sediments provides a direct analogue to other lowland crystalline terrains as existed immediately prior to pleistocene glaciation large granite intrusions exist in the sudetes and its foreland that support hills that range in size from small tors to large domes these terrains experienced only thin ice cover for short periods when the scandinavian ice sheet reached its pleistocene maximum limits in marine isotope stage mis 12 elsterian at 440 430 ka and mis 8 early saalian at 250 240 ka in each of four study areas beyond at and within the limits of glaciation we have mapped glacial erosion indicators glacial landform assemblages that indicate progressive glacial modification of the pre glacial granite terrain we find that glacial erosion increases with distance from the ice margin due to greater ice thickness and longer ice cover but has had only limited impact on hills regolith was stripped by moving ice tors were demolished and blocks were entrained however indicators of more advanced glacial erosion such as lee side cliffs and glacial streamlining are absent even from granite domes that lay beneath 500 m of ice the survival of tors beneath ice cover and the removal of tor superstructure by glacial erosion are confirmed the presence of glacially modified tors in areas covered only by elsterian ice implies that the tors existed before 440 ka moreover the contrast between blockfield covered slopes found above elsterian and saalian glacial trimlines on summits of granite gabbro and basalt hills in the sudetic foreland and glacially stripped surfaces at lower elevations implies only limited regeneration of blockfields since 430 and 240 ka the first stages of roche moutonnee formation are recognised in the exhumation of tor stumps but development of lee side steps remains very limited granite domes retain a pre glacial morphology and local examples of hill asymmetry are determined by structural rather than glaciological controls development of roches moutonnees and asymmetric and streamlined hills by glacial erosion has not occurred in the sudetes despite the passage of largely warm based ice sheets 80 500 m thick that persisted for 5 20 ka

restoration and evolution of the intermontane indus molasse basin ladakh himalaya india abstract collision of the indian plate with the karakorum plate lhasa block during the eocene ca 55 50 ma created predominantly a s or sw verging thrust culmination across the himalaya during the late tertiary two molasse basins existed the siwalik bain formed in the late miocene to present on the indian foreland south of the himalaya and the mid eocene to late miocene indus basin along the indus suture zone north of the high himalaya the indus basin is approximately 2000 km long extending eastwards from ladakh across south tibet a balanced cross section along the zanskar river shows a minimum 36 km shortening in the eocene late miocene molasse and suggests that the minimum basin width was approximately 60 km in ladakh more than 2000 m of post eocene alluvial fan fluvial and fluvio lacustrine sediments accumulated in the ladakh sector with petrographies suggesting derivation mainly from the deeply dissected and uplifted northern granodioritic ladakh batholith aptian eocene with only minor amounts of debris derived from the deformed southern tethyan passive margin palaeocurrents show predominant e w axis parallel sediment transport with subordinate lateral input paths being preserved the indus molasse basin is deformed by numerous post eocene n directed backthrusts many of which cut the entire stratigraphy and therefore were active at least into late tertiary times

proximal braidplain deposits in the middle devonian malbaie formation of eastern gaspe quebec canada the middle devonian malbaie formation of eastern gaspe canada comprises sharply alternating conglomerate and sandstone units their petrography suggests derivation from the same source but palaeocurrents indicate different dispersal systems for the sand and gravel the principal conglomerate facies is horizontally stratified with well developed imbrication characteristic of deposition on a high energy proximal braidplain minor cross stratified conglomerate shows well defined size sorting attributed to avalanching down foresets and sorting within minor bedforms on bar tops the sandstone units mainly comprise erosion surfaces overlain by mudstone intraclasts alternating with lineated low angle to horizontally stratified sandstone or trough cross stratified sandstone the sandstone units were deposited on a proximal braidplain with highly variable discharge but the absence of calcrete indicates that dry periods were not prolonged the malbaie is the coarsest uppermost formation of a devonian clastic wedge formed during the acadian orogeny the uniformity of facies association and palaeocurrents particularly in conglomerate units indicates derivation from a broad upwarp to the south this implies that the acadian uplands resulted from straight compression in contrast to the localized uplifts formed by strike slip faulting during the carboniferous

supervised classification of types of glaciated landscapes using digital elevation data abstract automated approaches for identifying different types of glaciated landscapes using digitally processed elevation data were evaluated we tested the ability of geomorphic measures e g elevation relative relief roughness and slope gradient derived from digital elevation models dems to differentiate glaciated landscapes using maximum likelihood classification and artificial neural networks ann the automated methods were trained and validated using an existing quaternary geology map and a manual interpretation of the contour data portrayed on topographic quadrangles the need for such methods arises from efforts to classify types of landscapes e g ecoregions in michigan one fundamental control of the landscape structure in michigan including soil type and vegetation is the underlying sedimentary and landform assemblages produced by an array of glacial processes during the waning phase of the pleistocene traditional methods for identifying different landscapes e g ice contact landscapes stagnation landscapes have relied on printed topographic maps and have been very effective but time consuming the maps resulting from the four supervised classification trials had between 51 and 61 agreement with the original quaternary geology map the output from the maximum likelihood classification had slightly higher agreements than the output from the neural net which is attributed to the generalization inherent in the quaternary geology map compared with the nature of the classifier for the neural net the neural net however identifies significant detail and non linear relationships between classification inputs and output classes future work should incorporate a map of soils into the classification

migration of petroleum into vermilion 14 field gulf coast u s a molecular evidence abstract oils and condensates from vermilion 14 field offshore louisiana u s a are compared using sulfur and nitrogen concentrations whole oil carbon isotope ratios and hydrocarbon distributions all parameters suggest large differences in the organic facies of the source rock s and in thermal maturity of the source at the time of expulsion certain bulk geochemical data including n alkane distributions and whole oil carbon isotope ratios suggest that migration fractionation resulted in oils condensates whose molecular distributions are shifted significantly toward lower molecular weight components migration contamination is supported by the occurrence in the oils of unsaturated and thermally unstable hydrocarbons including oleanenes dammarenes and diasterenes and molecular maturity ratios indicative of immature organic matter molecular maturity ratios of the oils increase with increasing reservoir depth regardless of reservoir lithology or formation for example the 20s 20s 20r 5 h 14 h 17 h 24 ethylcholestane ratio increases from 0 05 to 0 58 over a depth range of 6316 ft to 15 563 ft the same ratio for cuttings extracts from two wells in the vermilion 14 field shows lower values although they also increase with increasing depth it is proposed that the vermilion hydrocarbons were generated from deep source rocks approximately 15 000 ft or more and possibly subjected to migration fractionation during movement to shallower reservoirs during migration and after trapping migration contamination added unsaturated hydrocarbons to the oils condensates resulting in anomalously low molecular maturity ratios we suggest further that the combined effects of migration fractionation and migration contamination resulted in oil in the vermilion 14 field that is compositionally different from that which initially left the deep source rock

hydrothermal petroleums from yellowstone national park wyoming u s a abstract in yellowstone national park oil is actively discharging with thermal waters at several widely separated thermal areas samples from two locations were studied petroleum from calcite springs occurs as vapor condensates in steam vents detailed geochemical analyses show a complex origin for the petroleum fluid deeply buried hydrothermally altered sedimentary rocks are believed to have contributed a high temperature pyrolysate consisting largely of polynuclear aromatic hydrocarbons and heterocyclic compounds shallow sedimentary rocks which are also hydrothermally altered have contributed large amounts of aromatic and polar compounds as well as minor amounts of hydrocarbons the permian phosphoria formation is suggested as a likely source rock for the bulk of the oils autochthonous pyrolysates and lipids from thermally altered surface and near surface bacterial and land plant debris have also been introduced to the vents the latter may have been introduced by downward percolating meteoric water the oil from rainbow springs is a highly paraffinic low s crude oil depleted in light hydrocarbons unlike the calcite springs samples the oil from rainbow springs is believed to have originated from a single sedimentary source rock with little or no hydrocarbon contributions from surface biota the oil contains a unique molecular marker assemblage that suggests both gymnosperm and angiosperm input and places the age of the source unit in the tertiary consideration of the local stratigraphy and water temperatures limits the probable source zone to the eocene aycross formation an intra volcanic lacustrine mudstone calculation of deep water temperatures indicates that this unit is exposed to thermal waters in an extensive near surface aquifer such conditions are consistent with the widespread surface manifestations and biomarker kinetic models consideration of the petroleum chemistry and regional hydrodynamics indicates that the yellowstone park oils did not migrate into the park from distant sources the chemical data are also inconsistent with the oils being generated and trapped prior to tertiary volcanism at both calcite springs and rainbow springs oil generation appears to be contemporaneous and is attributed to thermal alteration of relatively shallow sedimentary rocks by hydrothermal fluids

automated classification of landform elements using object based image analysis this paper presents an automated classification system of landform elements based on object oriented image analysis first several data layers are produced from digital terrain models dtm elevation profile curvature plan curvature and slope gradient second relatively homogenous objects are delineated at several levels through image segmentation these object primatives are classified as landform elements using a relative classification model built both on the surface shape and on the altitudinal position of objects so far slope aspect was not used in classification the classification has nine classes peaks and toe slopes defined by the altitudinal position or the degree of dominance steep slopes and flat gentle slopes defined by slope gradients shoulders and negative contacts defined by profile curvatures head slopes side slopes and nose slopes defined by plan curvatures classes are defined using flexible fuzzy membership functions results are visually analyzed by draping them over dtms specific fuzzy classification options were used to obtain an assessment of output accuracy two implementations of the methodology are compared using 1 romanian datasets and 2 berchtesgaden national park germany the methodology has proven to be reproducible readily adaptable for diverse landscapes and datasets and useful in respect to providing additional information for geomorphological and landscape studies a major advantage of this new methodology is its transferability given that it uses only relative values and relative positions to neighboring objects the methodology introduced in this paper can be used for almost any application where relationships between topographic features and other components of landscapes are to be assessed

paleomagnetic chronology fluvial processes and tectonic implications of the siwalik deposits near chinji village pakistan a 2800 m section of siwalik strata containing the stratotypes for both the chinji and nagri formations has been dated by magnetic polarity stratigraphy and the observed polarity zonation has securely been correlated with the chron 17 7 segment of the time scale the base of the section is the base of the kamlial formation which occurs near the top of chron 17 18 3 m y the kamlial chinji formation boundary occurs in the middle of chron 15 14 3 m y the chinji nagri boundary near the bottom of chron 10 10 8 m y and the nagri dhok pathan boundary at the chron 8 9 boundary 8 5 m y the siwalik deposits near chinji village consist of four distinct classes of fluvial cycles each with a characteristic periodicity a first order of 10 7 years a second order of 10 6 years a third order of 10 4 10 5 years and a fourth order of 10 0 10 4 years the river system responsible for siwalik sedimentation flowed from west to east and had properties much like the modern ganges river syste

transition from foreland to piggyback basin deposition plio pleistocene upper siwalik group shinghar range nw pakistan plio pleistocene synorogenic deposits of the upper siwalik group in the shinghar range trans indus salt ranges of north western pakistan record the transition from foreland basin to piggyback basin deposition on the hangingwall of the salt range thrust the siwalik and upper siwalik groups are over 4 km thick in the shinghar range the lower 3 km consists of the miocene siwalik group which was deposited by a south flowing foreland trunk stream the palaeo indus river the upper 1 5 km consists of the upper siwalik group which is herein divided into three members the lowest member includes deposits of the south flowing palaeo indus river and is distinguished from the underlying siwalik group by the first appearance of conglomerate the transition from the lower member to the middle member is interpreted as recording uplift on the salt range thrust as the salt range thrust was active the palaeo indus river was bifurcated to the east and west around the embryonic shinghar range and overbank and lacustrine deposition occurred represented by the middle member when the shinghar range achieved significant topography the upper member was deposited by streams transporting gravel and sand that flowed north and west out of the range and into a piggyback basin that formed on the hangingwall of the salt range thrust new and previously published palaeomagnetic stratigraphy and fission track ages from volcaniclastic deposits within the upper siwalik group provide tight constraints on the chronology of sedimentary facies transitions and timing of uplift of the shinghar range the integration of sedimentological and geochronological data indicates that motion on the salt range thrust and repositioning of the indus river began at 1 0 ma

aliphatic and aromatic triterpenoid hydrocarbons in a tertiary angiospermous lignite abstract the hydrocarbon biomarker assemlage of a liptinite rich early tertiary angiospermous lignite has been characterized the biomarker fistribution for the lignite confirms the low maturity and previous paleobotanic interpretations the aliphatic hydrocarbon fraction consists predominantly of n alkanes showing a strong odd carbon predominance and numerous de a triterpenoids and triterpenoids derived from higher plants bacterially derived triterpenoids were represented primarily by homohopanes and hopenes the aromatic hydrocarbon fraction contains a series of mono di and triaromatic de a triterpenoids and mono tri and tetraaromatic triterpenoids derived from higher plants the concentration and abundance of monoaromatic triterpenoids containing one to three additonal degress of unsaturation have not seen previously observed in a single deposit as such a diagenetic scheme for angiosperm derived triterpenoids is presented which confirms and extends previous hypothesis

monitoring tectonically controlled marine to lacustrine transitions using organic facies ridge basin california u s a abstract ridge basin is an elongate intermontane basin filled with upper miocene pliocene clastics located 80 km north northwest of downtown los angeles over 13 km of marine lacustrine and fluvio deltaic sandstones and shales are present because of southeastward depocenter migration throughout basin development no more than 4 5 km of vertical section are present in any one location this has resulted in an ideal situation to study organic facies variability namely a thick thermally immature stratigraphic succession with only minor variations in maturity level in this paper we use molecular isotopic and petrographic data to help identify systematic variability in organic facies in the castaic ridge route and peace valley fms all late miocene and relate these variations to the paleolimnology tectonic history and oil source rock potential of the basin as strike slip movement continued along the san gabriel fault during the late miocene the sedimentation regime changed from a marine dominance to one controlled by lacustrine and fluvio deltaic processes this transition results in changes in the organic facies within the basin as reflected in a a systematic decrease in organic carbon isotope ratios b an increase in relative yields of phenolic and n aliphatic structures in the kerogen pyrolysate c an increasing occurrence of perhydro carotene indicating episodic development of a halocline in the water column and d decreasing pristane phytane and c 29 c 28 sterane ratios unusual patterns of kerogen maceral distribution and a ring sterane methylation are also observed these geochemical data support the existence of a marine embayment in the early late miocene yielding to a lacustrine and fluvio deltaic setting which experienced considerable variation in bathymetry salinity and oxicity low levels of thermal maturity preclude the occurrence of hydrocarbon source rocks although source rock potential is present in sporadic localities optical and molecular maturity indicators show no systematic variation with stratigraphic succession this lack of variation is consistent with the known tectonic development in the basin and the shingled sedimentation pattern resulting from a migrating depocenter internal variability in the sterane and hopane epimer ratios may eventually be useful in estimating the uneven extent of overburden in the peace valley and ridge route fms leading to applications elsewhere in intermontane lacustrine basins with tectonically migrating depocenters

reconstruction of floral changes during deposition of the miocene embalut coal from kutai basin mahakam delta east kalimantan indonesia by use of aromatic hydrocarbon composition and stable carbon isotope ratios of organic matter the distribution of aromatic hydrocarbons and stable carbon isotope ratios of organic matter in a series of nine miocene embalut coal samples obtained from nine coal seams of kutai basin east kalimantan indonesia were studied the rank of the embalut coals ranged from lignites to low rank sub bituminous coals 0 36 0 50 rr based on measurements of huminite reflectance the aromatic hydrocarbon fractions of all coal samples were dominated by cadalene in the lower boiling point range and picene derivatives in the higher boiling point range of the gas chromatograms cadalene can be attributed to the contribution of dipterocarpaceae and various hydrated picenes to the contribution of additional angiosperms to the coal forming vegetation the picenes originate from alpha and beta amyrin however in some coal samples minor amounts of simonellite and retene were also detected which argues for an additional contribution of gymnosperms conifers to coal forming vegetation preferentially in the middle miocene and at the beginning of the late miocene the results of stable carbon isotope ratios d 13

bicadinanes in oils from the surma basin bangladesh abstract bicadinanes c 30 pentacyclic triterpanes have only been reported in crude oils and sediment extracts from s e asia the present investigation indicates that they are also widely present in land plant derived tertiary oils from the surma basin of n e bangladesh oleanane is also abundant in these oils though its distribution does not correlate with those of the bicadinanes this is consistent with separate specific land plant sources for these two classes of triterpanes and with the formation of bicadinanes during maturation of polymerised angiosperm tree resin

stable isotope analysis of the tooth enamel of chaingzauk mammalian fauna late neogene myanmar and its implication to paleoenvironment and paleogeography abstract the tooth enamel of a mammalian fauna from the uppermost miocene lower pliocene irrawaddy sediments at chaingzauk west central myanmar were analyzed using stable carbon and oxygen isotopes the 13 c values of porcupines tragulids rhinocerotids suids and proboscideans show that these mammals preferentially consumed c 3 plants in a wooded environment whereas the 13 c values of bovids and hippopotamids indicate that they were grassland adapted grazers to mixed feeders in contrast to the thorn scrub grassland and shrubland vegetation of present day central myanmar stable carbon isotope results of the chaingzauk fauna suggest a presence of wooded environment in the chaingzauk area at that time present day arid conditions are likely to have been caused by the uplift of the indo burman ranges due to the himalayan orogeny during the late miocene to pliocene resulting in a rainshadow effect in central myanmar furthermore southward marine regression due to the rapid influx of sediments from the indo burman ranges eastern himalayan ranges and sino burman ranges into the central myanmar basin in the miocene to pliocene might have played an important role in the aridification of this region since the lower pliocene

morphology sedimentology and palaeohydraulic significance of large gravel dunes altai mountains siberia coarse gravel bedforms which resulted from pleistocene glacial outburst floods are identified as subaqueous dunes comparison of the morphology of these fossil structures with modern dunes shows that the form of two dimensional 2 d transverse dunes and 3 d cuspate and lunate dunes developed in coarse gravels is comparable with sand dune morphology within lesser scale geophysical flows the similarity of the steepest gravel dunes with equilibrium dunes in sand indicates that grain size is not a major factor in constraining primary duneform internal structure indicates that flow over 2 d dunes was relatively uniform but over 3 d bedforms flow was locally variable flow separation and complex streaming of flow occurred over the steepest 3 d dunes cross beds are thin and few approach the angle of repose consequently most dunes did not migrate primarily by avalanching but by stoss entrained gravel transported over the crests rolling down and depositing on the lee slopes the lee formed when flood power was waning some dunes were siightly planed down during falling stage because lee side cross beds tend to be steeper than the angle of the preserved lee slope however silt rich caps indicate that any height reduction was contemporary with the final deposition of foresets post flood modification has been negligible although the modern topography is subdued by loess deposits within the dune troughs lee side sediments are often finer than the stoss slope sediments which indicates

sedimentology of the indus group ladakh northern india implications for the timing of initiation of the palaeo indus river the upper reaches of the indus river form a longitudinal network that drains a large portion of the western himalaya it plays an important role as a sediment routing system feeding the indus delta and submarine fan and has played a controlling role in the denudational history of the western himalaya given the rivers long term significance its timing of initiation remains poorly constrained the facies palaeocurrents and provenance of the post early eocene indus group preserved along the upper reaches of the modern indus reveal a history of fluvial deltaic and deep water sedimentation in an intermontane basin dominated by internal drainage hence the indus group is not considered to represent the deposits of a palaeo indus river as previously thought illite crystallinity values and apatite fission track dating of the indus group suggest that the succession was buried to temperatures of 155 280 c and that unroofing started in early miocene times and proceeded at 0 1 0 4 mm a 1 to the present the youngest sedimentary rocks preserved along the indus basin are early miocene in age from the tectonostratigraphically equivalent deposits around kargil to the west of the study area the transition from sediment accumulation to erosional unroofing in early miocene times coincides with accelerated regional unroofing of the high himalayas to the south and the initiation of the indus delta submarine fan to the west differential uplift between the northward thrusting of the zanskar and indus sedimentary succession against the undeformed ladakh batholith provides a mechanism for post early miocene initiation of a major longitudinal river hence early miocene times is believed to represent the earliest possible age of initiation of the palaeo indus river following this course

higher plant biomarker signatures of early eocene sediments of north eastern india abstract the biomarkers molecular fossils of paleobiota have been studied in detail from a coal bearing sequence of early eocene lakadong sandstone member of sylhet formation of upper assam basin ne india using gas chromatography mass spectrometry corresponding hydrocarbon source potential of the same unit has been studied using rock eval pyrolysis the rock eval data suggest dominant terrestrial land plant contribution i e type iii kerogen and the sediments of the section had entered the early stage of catagenesis the alkane and isoprenoid distributions are characterized by odd over even preference oep 1 1 1 2 of n alkanes and high pristane phytane ratio 2 9 7 6 which corroborate the rock eval data the distribution of aliphatic biomarkers is characterized by dominance of c24 tetracyclics over c23 tricyclics high concentration of des e hopane moderate to high c29 c30 hopane ratio extremely low oleanane index and low c35 homohopane index the extremely low oleanane index is correlated with a high degree of aromatization of oleanane skeleton favoured by acidic swampy depositional environment the presence of diterpanes at the base of the early eocene section indicates contribution from gymnosperms coniferales order of land plants whereas angiospermous biomarkers with oleanoid skeleton are also preserved this pattern subsequently evolved to angiosperm dominated towards the top of the section with no gymnosperm signature indicating possible climatic variation during the early eocene towards the top of the section presence of bicadinanes indicates contribution of dipterocarpaceae family of trees and advent of the evergreen tropical rain forest element in eastern india in early eocene similar to the pattern found in western india e g cambay and kutch basins

longitudinal and transverse profiles of hilly and mountainous watersheds in japan abstract digital elevation models dems at 1 m resolution for small bare lands 0 18 0 43 km 2 and at 10 m resolution for broad forested areas 28 9 100 5 km 2 in japanese hills and mountains were utilized for quantitative analyses of longitudinal and transverse profiles of watersheds with special attention to changes in watershed form with regional relief statistical morphometric parameters representing the shape of these profiles were investigated a previous study on a small steep watershed in japan showed that the longitudinal and transverse characteristics of watersheds play different roles in determining the entire watershed topography although some of the parameters representing the two characteristics are systematically related this paper expands such analyses into various relief levels and larger spatial scales for instance average watershed slope in the high relief areas mainly reflects the longitudinal slope while the effects of the transverse slope become stronger in the lower relief areas most topographic characteristics of watersheds in the high relief areas are simpler and more organized than those in the low to middle relief areas indicating that high relief terrains have more mature conditions close to equilibrium however geomorphological complexity of watersheds does not always decrease with increasing relief because differences in bedrock erodibility also affect watershed topography

geochemical characterization and source investigation of oils discovered in khoraghat nambar structures of the assam arakan basin india abstract we examined the geochemical compositions of the newly discovered bokabil and sylhet oils and of the extracts of potential source rock samples from the khoraghat nambar area of the assam arakan basin india stable carbon isotopic compositions and a number of biomarkers indicate that oils in the bokabil formation early to middle miocene can be correlated across the khoraghat and nambar fields however oil from the sylhet formation middle to late eocene is distinct from those in the bokabil formation late eocene to early oligocene barail coal shale and middle to late eocene kopili shale sequences are identified as potential source rocks both strata contain organic matter predominantly derived from higher land plants however different organofacies exist for barail coal shale and kopili shale sequences that can be distinguished by the stable carbon isotopic compositions and biomarker distributions an oil source correlation study shows that barail rock extracts are genetically correlatable with the bokabil oils whereas kopili rock extracts have similar source specific parameters to those of the sylhet oil thus the study suggests the presence of two petroleum systems in the khoraghat nambar area the barail bokabil and the kopili sylhet petroleum systems barail and kopili sediments from the study area are of lower maturity than the oils suggesting that the actual source strata are more mature equivalents likely to be present in the naga schuppen zone therefore areas in and around the naga schuppen zone where better reservoir facies are expected are favoured targets for further exploration

sedimentology of plio pleistocene late orogenic deposits associated with intraplate subduction the upper siwalik subgroup of a part of panjab sub himalaya india abstract this study provides a detailed sedimentologic documentation of the lithofacies cyclicity sandbody geometry palaeoflow variability and depositional models of the youngest late orogenic deposits of the siwalik molasse these deposits represent one of the important examples of sedimentation in the zone of intraplate subduction of the himalayan collision belt lithofacies analysis has resulted in the recognition of four conglomerate facies massive matrix supported conglomerate crudely stratified conglomerate trough cross stratified conglomerate planar cross stratified conglomerate five sandstone facies erosional scour and fill pebbly sandstone medium to coarse grained sandstone fine to medium grained ripple drift laminated sandstone bioturbated calcareous fine grained sandstone and six mudstone facies parallel laminated bioturbated mudstone reddish brown massive mudstone variegated mudstone bluish grey to violet mudstone buff coloured mudstone pebbly mudstone in addition hard calcareous layers have been recognised as a separate facies state the deduced cyclic sequences of the tatrot and pinjor formations of the upper siwalik subgroup show fining upward characters from cs coarse sandstone to ms mudstone through fs fine sandstone and ss alternations of sandstone and siltstone the sandbodies of the tatrot and pinjor formations reveal a sheet like geometry and an internal dominance of inter storey scour surfaces the presence of intraformational debris mud drapes reactivation surfaces and a general fining upward of grain size indicates fluctuating hydrodynamic conditions with frequent channel abandonment and re occupation resulting in net vertical aggradation the dominant style of sedimentation both in the channel and overbank facies is through vertical aggradation data on the palaeoflow variability indicates that the upper siwalik subgroup can be subdivided into four and three sediment vector sequences in the khetpurali and ghaggar sections respectively the palaeodrainage pattern in the khetpurali section reveals a major influence of northerly drainage twice in the stratigraphic column the high percentage of overbank deposits in individual cycles the lack of vegetal debris organic poor palaeosol units and abundant syngenetic caco 3 activity warrant comparison with the modern anastomosed deposits described from arid central australia some intervals of the sequences are comparable to the sublinear subparallel drainages with local anastomosis of the modern piedmont zone of the himalaya the higher parts of the stratigraphic column indicate proximal braided stream deposits and finally proximal alluvial fan deposits syntectonic activity has controlled the deposition of the megasequences which are a response to episodicity in the activity of basin margin basin margin or basin margin intrabasin structures the vertical stacking of the siwalik megasequences appears to be episodic in character

elementary forms for land surface segmentation the theoretical basis of terrain analysis and geomorphological mapping abstract land surface morphology is fundamental to geomorphological mapping and many gis applications review and comparison of various approaches to segmentation of the land surface reveals common features and permits development of a broad theoretical basis for segmentation and for characterization of segments and their boundaries within the context of defining landform units that maximise internal homogeneity and external differences this paper introduces the concept of elementary forms segments units defined by constant values of fundamental morphometric properties and limited by discontinuities of the properties the basic system of form defining properties represents altitude and its derivatives constant values of which provide elementary forms with various types of homogeneity every geometric type of elementary form can be characterized by a defining function which is a specific case of the general polynomial fitted function various types of boundary discontinuity and their connections and transformations into other types of morphological unit boundaries are analysed the wealth of types of elementary forms and their boundaries is potentially unbounded and thus is sufficient to cover the real variety of landforms elementary forms in the basic set proposed here have clear potential for genetic and dynamic interpretation a brief worked example documents the possibility of analytical computation of various models of ideal elementary forms for particular segments of landform ideal elementary forms can be considered as attractors to which the affinity of surface segments can be measured by multivariate statistical methods the use of the concept of elementary forms in landscape segmentation is promising and it could be adapted for elementary segmentation of various other spatial fields