cenozoic topographic and climatic response to changing tectonic boundary conditions in western north america abstract this study presents an oxygen isotopic record from the paleocene to the pliocene based on the analysis of predominantly paleosol carbonate from intermontane basins in southwestern montana and eastern idaho 18 o values of calcite decrease by 7 to 10 between 50 and 47 ma in southwestern montana and idaho most likely as a result of an increase in elevation of 2 5 to 3 5 km this rise in elevation is roughly contemporaneous with the emplacement of the nearby challis volcanics and the formation of metamorphic core complexes in the hinterland of the sevier thrust belt moreover when compared to previous oxygen isotopic studies that show oxygen isotopic shifts of similar magnitude occurring later in the late eocene to early oligocene in northeastern nevada and late oligocene to miocene in southern nevada the results of this study add to a growing body of evidence for a spatial and temporal migration of high surface elevations from north to south in the great basin of western united states this surface uplift history supports tectonic models calling for north to south removal of the farallon slab or delamination of the mantle lithosphere

glass from the cretaceous tertiary boundary in haiti tektite like glasses preserved at the cretaceous tertiary boundary at beloc in haiti provide clear evidence of an impact event the glass composition suggests that the impact occurred on a continental shelf region generating a silica rich glass with chemical composition that reflects the melting of continental crustal rocks and a calcium rich glass produced by the fusion of marl sediments these findings indicate that catastrophic release to the atmosphere of 1015 moles of c02 from vaporized marl occurred during the impact

impact of underground coal fire on coal petrographic properties of high volatile bituminous coals a case study from coal fire zone no 3 2 in the wuda coalfield inner mongolia autonomous region north china abstract the wuda coalfield located in the inner mongolia autonomous region north china is known as one of china s major source of prime coking coals and a site of well researched and well documented underground coal fires the underground coal fire at the coal fire zone no 3 2 is situated in the active coal mine of suhai tu located in the north westerly part of the wuda coalfield the present paper investigates the impact of the underground coal fire on the coal seam no 10 by application of coal petrographic methods including detailed characteristic of macerals and other coal components maceral analysis microstructural analysis and vitrinite reflectances performed on 1 coal grains lacking impurities microfractures dark oxidation rims 2 on dark rimmed vitrinite as well as 3 on low temperature semi coke the investigated coal seam no 10 represents a high volatile a bituminous coal and is dominated by vitrinite followed by inertinite with minor amounts of liptinite and by non isotropic low temperature semi coke the microstructure of the oxidatively and thermally altered coals is represented by 1 extensive non tectonic microfissures and non tectonic microfractures i e shrinkage microfractures leading to defragmentation of coal grains 2 dark oxidation rims observed at grain margins non tectonic microfissures and microfractures and by 3 devolatilisation micropores random vitrinite reflectances measured in 1 coal grains lacking impurities microfractures and dark oxidation rims and in 2 dark rimmed vitrinite at non tectonic microfissures and fractures reveal significant lateral variations the presence of low temperature semi coke and its marked lower reflectance values are indicative of thermal alteration induced by the underground coal fire in the coal fire zone no 3 2 the results obtained from the performed analyses of organic matter point to both low temperature oxidation and low temperature pyrolysis processes the applied coal petrological approach revealed characteristic changes to the coal s microstructure its petrographic composition as well as to optical properties induced by the underground coal fire

late pleistocene holocene ruptures of the lima reservoir fault sw montana abstract active tectonics within the northern basin and range province provide a natural laboratory for the study of normal fault growth linkage and interaction here we present new geologic mapping and morphologic fault scarp modeling within the centennial valley montana to characterize pleistocene holocene ruptures of the young and active lima reservoir fault geologic relationships and rupture ages indicate middle pleistocene activity on the henry gulch 50 ka and 23 10 ka trail creek 43 ka and 13 ka and reservoir 23 ka segments offset quaternary deposits also record holocene rupture of the reservoir segment 8 ka but unfaulted modern streams show that no segments of the lima reservoir fault have experienced a large earthquake in at least several millennia the clustered pattern of rupture ages on the lima reservoir fault segments suggests a seismogenic linkage though segment length and spacing make a physical connection at depth unlikely trail creek and reservoir segment slip rates were non steady and appear to be increasing the fault helps accommodate differential horizontal surface velocity measured by gps geodesy across the boundary between the northern basin and range province and the snake river plain

evidence for synchronous thin skinned and basement deformation in the cordilleran fold thrust belt the tendoy mountains southwestern montana the tendoy mountains contain the easternmost thin skinned thrust sheets in the cordilleran fold thrust belt of southwestern montana and are in the zone of tectonic overlap between the rocky mountain foreland and the cordilleran fold thrust belt the three frontal thrust sheets of the tendoy mountains are from north to south the armstead mckenzie and tendoy sheets near the southeastern terminus of the tendoy thrust sheet is a lateral ramp in which the tendoy thrust climbs along strike from the upper mississippian lombard limestone to lower cretaceous rocks this ramp coincides with the southeastern side of the paleozoic snowcrest trough and projection of the range flanking basement thrust of the blacktail snowcrest uplift suggesting either basement or stratigraphic control on location of the lateral ramp axes of major folds on the southern part of the tendoy thrust sheet are parallel to the direction of thrust transport and to the trend of the snowcrest range they are a result of 1 pre thrust folding above basement faults 2 passive transportation of the folds from a down plunge position 3 minor reactivation of basement faults and 4 emplacement of blind sub tendoy thin skinned thrust faults the tendoy sheet also contains a major out of sequence thrust fault that formed in thick upper mississippian shales and created large overturned foreland verging folds in upper mississippian to triassic rocks the out of sequence fault can be identified where stratigraphic section is omitted and by a stratigraphic separation diagram that shows it cutting down section in the direction of transport the prominent lateral ramp at the southern terminus of the tendoy thrust sheet is a result of fault propagation through strata folded over the edge of the blacktail snowcrest uplift

greenhouse gas emissions from low temperature oxidation and spontaneous combustion at open cut coal mines in australia abstract spontaneous combustion and low temperature oxidation of waste coal in open cut coal mines represents a potentially large source of greenhouse gas emissions in this paper emission fluxes of co2 and ch4 from spoil piles and waste coal dumps measured at 11 mines in the hunter valley and bowen basin in australia are presented the data displayed considerable scatter which is consistent with the inhomogeneous nature of spoil pile material and permeability of surfaces despite the scatter emissions were able to be classified into three broad categories according to the intensity of the spontaneous combustion present in the material average emissions ranged from about 12 kg co2 e yr 1 m 2 to 8200 kg co2 e yr 1 m 2 depending on the intensity of the spontaneous combustion there was also within the scatter of the data an approximately linear trend of increasing emission flux with increasing surface temperature a key finding of the research is that the emission rates of greenhouse gases from spoil piles where there is no spontaneous combustion but only low temperature oxidation of coal and coal waste are similar to the emission rates due to biological activity from vegetated surfaces however further research is required to quantify the degree to which spoil piles that have no spontaneous combustion contribute to the anthropogenic atmospheric co2 burden

provenance of synorogenic foreland basin strata in southwestern montana requires revision of existing models for laramide tectonism north american cordillera

the cretaceous tertiary boundary cocktail chicxulub impact triggers margin collapse and extensive sediment gravity flows a distinctive mixture of reworked microfossils impact derived materials and lithic fragments occurs in sediments at the cretaceous tertiary boundary in the basinal gulf of mexico and caribbean we have named this mixture the cretaceous tertiary boundary cocktail lithologic and paleontologic evidence suggests that the cocktail was deposited by giant sediment gravity flows apparently triggered by the collapse of continental margins around the gulf of mexico as a result of the chicxulub impact as most microfossils in the gravity flow units are reworked biostratigraphy provides only maximum ages recognition of the cocktail is a reliable way to identify cretaceous tertiary boundary deposits in the basinal gulf of mexico and caribbean

the global stratigraphy of the cretaceous tertiary boundary impact ejecta the chicxulub crater ejecta stratigraphy is reviewed in the context of the stratigraphy of underlying and overlying rock sequences the ejecta sequence is regionally grouped in a thick polymict and monomict breccia sequences inside the crater and within 300 km from the rim of the crater known from drill holes in and close to the breater and exposures near the border of yucatan and belize b gulf of mexico region 2500 m from the crater with up to 9 m thick complex tsunami wave influenced tektite bearing sequences in shallow marine 500 m deep environments and tektite bearing decimeter thick gravity flow deposits in deep water sites c an intermediate region between 2500 and 4000 km from the crater where centimeter thick tektite bearing layers occur and d a global distal region with a millimeter thin ejecta layer the distal ejecta layer is characterized by sub millimeter sized microkrystites often rich in ni rich spinels and altered clinopyroxene wherever present the ejecta layers mark exactly the sudden mass mortality horizon of the k t boundary what exactly caused the mass mortality is still uncertain but it appears the main event leading to the k t mass extinctions

chicxulub multiring impact basin size and other characteristics derived from gravity analysis the buried chicxulub impact structure in mexico which is linked to the cretaceous tertiary k t boundary layer may be significantly larger than previously suspected reprocessed gravity data over northern yucatan reveal three major rings and parts of a fourth ring spaced similarly to those observed at multiring impact basins on other planets the outer ring probably corresponding to the basin s topographic rim is almost 300 kilometers in diameter indicating that chicxulub may be one of the largest impact structures produced in the inner solar system since the period of early bombardment ended nearly 4 billion years ago

potential health impacts of burning coal beds and waste banks uncontrolled release of pollutants from burning coal beds and waste banks presents potential environmental and human health hazards on a global scale the emissions of large volumes of greenhouse gases from burning coal beds may contribute to climate change that alters ecosystems and patterns of disease occurrence on regional and local scales the emissions from burning coal beds and waste banks of acidic gases particulates organic compounds and trace elements can contribute to a range of respiratory and other human health problems although there are few published reports of health problems caused by these emissions the potential for problems can be significant in india large numbers of people have been displaced from their homes because of health problems caused by emissions from burning coal beds volatile elements such as arsenic fluorine mercury and selenium are commonly enriched in coal deposits burning coal beds can volatilize these elements which then can be inhaled or adsorbed on crops and foods taken up by livestock or bioaccumulated in birds and fish some of these elements can condense on dust particles that can be inhaled or ingested in addition selenium arsenic lead tin bismuth fluorine and other elements condense where the hot gaseous emissions come in contact with ambient air forming mats of concentrated efflorescent minerals on the surface of the ground these mats can be leached by rainwater and washed into local water bodies providing other potential routes of exposure although there are little data linking burning coal beds and waste banks to known health problems a possibly analogous situation exists in rural china where mineralized coal burned in a residential environment has caused widespread and severe health problems such as fluorosis and arseniasis

tektites in cretaceous tertiary boundary rocks on haiti and their bearing on the alvarez impact extinction hypothesis relic tektites are associated with a pt group metal abundance anomaly and shocked minerals in a thin marl bed that marks the k t boundary on haiti the presence of these three impact produced materials at the precise k t boundary enormously strengthens the alvarez impact extinction hypothesis the tektites occur in smectite spherules that have external shapes typical of tektites their chemical and physical properties are broadly similar to those of other tektite groups except that the haitian tektites have lower si and higher fe ca and na on average they contain more sc v cu zn ga sr sn and ba and less cr ni co b mn and hf than other tektite groups amounts of rare earth elements ree in the tektites indicate that their progenitor materials were not melted mafic or ultramafic oceanic crust rather they were sedimentary deposits having a bulk composition of andesite rare tektites contain unusually high amounts of cao 20 and s 0 4 and these data suggest that some target materials consisted of caso4 anhydrite beds occur in the subsurface at two candidate impact sites chicxulub and manson sm nd isotopic data for the tektites indicate that the melted precursor sediments were most likely deposited less than 400 m y between the late cretaceous and silurian periods major chemical changes accompanied the diagenetic change of glass to smectite the haitian tektites are the first datable impact products in k t boundary rocks and 40ar 39ar ages of the glass show that the k t boundary and impact event are coeval at 64 5 0 1 ma

chicxulub impact ejecta from albion island belize impact ejecta from the albion formation are exposed in northern belize the ejecta come from the outer portion of the continuous ejecta blanket of the chicxulub crater which is located 360 km to the northwest the basal unit of the albion formation is a 1 m thick clay and dolomite spheroid bed composed of up to four discrete flows the clay spheroids are altered impact glass and the dolomite spheroids are accretionary lapilli the upper unit is a 15 m thick coarse diamictite bed containing altered glass large accretionary blocks striated polished and impacted cobbles and rare shocked quartz the abundance of accretionary clasts evidence for atmospheric drag sorting and the presence of multiple flows in the albion formation indicate that atmospheres play an important role in the formation of the outer portions of continuous ejecta blankets of large craters

gaseous emissions and sublimates from the truman shepherd coal fire floyd county kentucky a re investigation following attempted mitigation of the fire abstract the truman shepherd coal mine fire floyd and knott counties kentucky has been the subject of several field investigations over the last four years during july and november 2011 and january 2012 field investigations we measured gas emissions collected minerals and characterized the nature of the fire new vents opened over the course of the study and have continued to open since january 2012 coincident with the eastward advance of the fire this is the first study of kentucky coal fires where the original vents were able to be studied in addition to new vents on each subsequent trip neoformed minerals associated with the vents are primarily ammonium sulfates and ammonium chlorides with minor zeolites btex emissions especially benzene vary considerably ranging from relatively low to comparable to those from very large fires such as the ankney coal fire in wyoming vent emission data collected displays a general trend of decreasing carbon dioxide and carbon monoxide emissions from july through january the projected annual greenhouse gas and mercury emissions from the fire are 65 69 t of co 2 4 51 t of co 5 73 t of ch 4 and 1 667 kg hg the november 2011 co co 2 ratios are indicative of more complete combustion than at any other time during the study possibly indicative of decreased moisture in the system

trace element emissions from spontaneous combustion of gob piles in coal mines shanxi china the emissions of potentially hazardous trace elements from spontaneous combustion of gob piles from coal mining in shanxi province china have been studied more than ninety samples of solid waste from gob piles in shanxi were collected and the contents of twenty potentially hazardous trace elements be f v cr mn co ni cu zn as se mo cd sn sb hg tl pb th and u in these samples were determined trace element contents in solid waste samples showed wide ranges as compared with the upper continental crust the solid waste samples are significantly enriched in se 20x and tl 12x and are moderately enriched in f as mo sn sb hg th and u 2 5x the solid waste samples are depleted in v cr mn co ni cu and zn the solid waste samples are enriched in f v mn cr co ni cu zn sb th and u as compared with the shanxi coals most trace elements are higher in the clinker than in the unburnt solid waste except f sn and hg trace element abundances are related to the ash content and composition of the samples the content of f is negatively correlated with the ash content while pb is positively correlated with the ash the concentrations of as mn zn and cd are highly positively correlated with fe2o3 in the solid waste the as content increases with increasing sulfur content in the solid waste the trace element emissions are calculated for mass balance the emission factors of trace elements during the spontaneous combustion of the gobs are determined and the trace element concentrations in the flue gas from the spontaneous combustion of solid waste are calculated more than a half of f se hg and pb are released to the atmosphere during spontaneous combustion some trace element concentrations in flue gas are higher than the national emission standards thus gob piles from coal mining pose a serious environmental problem

the cenozoic climatic and topographic evolution of the western north american cordillera herein we present oxygen isotope records from cretaceous to recent terrestrial sediments in the western north american cordillera the purpose of this analysis is to use oxygen isotope records to understand the coupled surface elevation and climate histories of this region through the cenozoic to do this we constructed 18o maps of surface waters for time intervals that trace the development of topography of western north america these maps are based on 4861 oxygen isotope analyses from both published 4478 and new 383 data we determined the 18o values of surface waters using paleotemperatures derived previously from floral assemblages and the appropriate isotope fractionation factors these data suggest that in the late cretaceous to early eocene the sevier hinterland formed a plateau of unknown height around 50 ma a topographic wave developed in british columbia and eastern washington that swept southward reaching northeastern nevada at 40 to 38 ma and southern nevada 23 ma this southward encroachment of an eocene plateau sweep caused reorganization of drainage patterns such that the intraforeland basins of wyoming and utah drainages extended deep within the sevier hinterland as the wave swept southward the landscape within the sevier hinterland developed into a rugged and high mountain range with the hypsometric mean elevation of 4 km and relief of 1 5 km this eocene highland was bordered on the west by a high sierra nevada ramp and on the east by the intraforeland basins that captured water draining these growing highlands the spatial and temporal evolution of this highland correlates with the timing of volcanism and extension these observations support tectonic models that call for north to south removal of the farallon slab or piecemeal removal of mantle lithosphere the isotopic data show that prior to growth of this highland the north american monsoon nam penetrated much farther north in the paleocene eocene than today the combined effects of global cooling increasing latitudinal temperature gradients and the generation of the orographic barrier created by the growing north to south highland produced a southward migration of the nam front by the oligocene the hydrologic regime that we observe today was in place it has been modified since then as a result of basin and range extension and collapse of the highlands in the mid miocene this collapse allowed the nam to penetrate farther north into the great basin of nevada and utah

geologic history of natural coal bed fires powder river basin usa abstract coal bed fires ignited by natural processes have baked and fused overlying sediments to form clinker a hard red or varicolored rock through much of the northern great plains of the united states usa the gently dipping coal beds in the region burn when regional downwasting brings them above the local water table the resulting clinker forms a rim along the exposed edge of the coal bed in an ongoing process through geologic time the resistant clinker is left capping buttes and ridges after the softer unbaked strata erode away clinker outcrops cover more than 4100 km2 in the powder river basin prb which lies in wyoming wy and montana mt the clinker in place records tens of billions of tons of coal that have burned releasing gases into the atmosphere the amount of clinker that has eroded away was at least an order of magnitude greater than the clinker that remains in place fission track and uranium thorium helium ages of detrital zircon crystals in clinker and paleomagnetic ages of clinker show that coal beds have burned naturally during at least the past 4 million years ma the oldest in place clinker that has been dated collected from a high isolated clinker capped ridge has a fission track age of 2 8 0 6 ma evidence of erosion and downcutting is also preserved by clinker clasts in gravel terraces one clinker boulder in a terrace 360 m above the yellowstone river has a fission track age of 4 0 0 7 ma coal bed fires are caused by lightning wildfires spontaneous combustion or human activity on coal outcrops and in mines miners government agencies and ranchers have extinguished thousands of coal bed fires but natural ignition continues where fresh coal has access to air at any given time hundreds of fires mostly small are burning in the powder river basin the total amount of coal burned by natural fires in the last 2 ma is one to two orders of magnitude greater than the total amount of coal removed by mining in the past century however current annual rates of coal mining are three to four orders of magnitude greater than estimated prehistoric annual rates of coal consumption by natural fires

distribution isotopic variation and origin of sulfur in coals in the wuda coalfield inner mongolia china abstract this paper describes coal petrographic characteristics sulfur abundance distribution and isotopic signature in coals in the wuda coalfield inner mongolia northern china petrographic studies suggest that depositional environment influences petrographic composition the no 9 and no 10 coal seams which are thought to have formed on a tidal delta plain have high collodetrinite contents up to 66 1 indicating enhanced gelification and bacteria activity during coal accumulation and also have the highest sulfur content 3 46 and 3 42 both organic and pyritic sulfur isotope values 12 3 to 5 8 and 18 7 to 1 1 respectively are variable and generally tend to be more negative in high sulfur coals than those in low sulfur coals in the wuda coalfield the negative sulfur isotope values indicate that a large portion of sulfur in the high sulfur coals has a bacterial origin sulfur isotopic compositions and variations within the section were used to propose a model to explain the origin of sulfur in these coals the presence of pyritized rod like bacteria cyanophyte s gelatinous sheaths and degraded algae organic matter suggests that bacteria and perhaps algae may play an important role in the formation of these high sulfur coals

chicxulub crater a possible cretaceous tertiary boundary impact crater on the yucatan peninsula mexico we suggest that a buried 180 km diameter circular structure on the yucatan peninsula mexico is an impact crater its size and shape are revealed by magnetic and gravity field anomalies as well as by oil wells drilled inside and near the structure the stratigraphy of the crater includes a sequence of andesitic igneous rocks and glass interbedded with and overlain by breccias that contain evidence of shock metamorphism the andesitic rocks have chemical and isotopic compositions similar to those of tektites found in cretaceous tertiary k t ejecta a 90 m thick k t boundary breccia also containing evidence of shock metamorphism is present 50 km outside the crater s edge this breccia probably represents the crater s ejecta blanket the age of the crater is not precisely known but a k t boundary age is indicated because the crater is in a thick carbonate sequence shock produced co2 from the impact may have caused a severe greenhouse warming

analysis of coal fire dynamics in the wuda syncline impacted by fire fighting activities based on in situ observations and landsat 8 remote sensing data abstract coal fires are a global catastrophe for valuable coal resources the environment human health and safety fire fighting activities are the approach to limit these catastrophic influences and to extinguish active coal fires the wuda syncline in inner mongolia is one of the biggest coalfields suffering from coal fires in china and is one of the coalfire areas globally which has been analyzed most comprehensively massive fire fighting activities have been undertaken to quench coal fires in the wuda syncline particularly activities such as blasting and excavation have accelerated since the year 2010 influence of fire fighting activities on coal fire dynamics is a significant topic but has rarely been reported yet although airborne and spaceborne earth observation data holds the potential to monitor extinguishing activities this data is rarely applied for this purpose airborne thermal scanner data is cost intensive to fly and spaceborne landsat 7 scanner system with a thermal band at 60 m spatial resolution in 2003 led to a limited exploitation of this valuable data source just recently landsat 8 satellite data with a thermal infrared band of 100 m spatial resolution is available since early 2013 and is able to fill this gap we conducted in depth in situ surveys on coal fires and fire fighting activities in the wuda syncline in may 2014 after visiting the wuda coalfield in 2012 we integrated our in situ observations and thermal anomalies extracted from both landsat 8 and landsat 7 slc on acquired before the scanner failure satellite data using an automated moving window thermal anomaly extractor regional anomaly extractor rae and analyzed coal fire dynamics impacted by fire fighting activities and the state of coal fires in the wuda syncline results show that after over 4 years of efforts to fight against coal fires in the wuda syncline the nos 1 7 no 9 no 12 and no 13 coal fire zones are extinct however the no 8 no 10 no 11 and no 14 no 18 coal fire zones are still active and furthermore three novel coal fire zones have evolved in the light of in situ surveys in the wuda coalfield these active and newly developed coal fires are mainly attributed to extinguishing related activities such as the blasting and excavation in fire affected areas which lead to the exposure of pure coal seams weathered coal pillars and coal waste piles to the outside air the contact of this coal and coal remnants with oxygen triggers spontaneous combustion of coal and further develops to coal fires additionally time series analyses of extracted thermal anomalies suggest that coal fires propagate eastward according with the dip direction of coal seams in the wuda coalfield the regional thermal anomaly extraction tool rae can delineate thermal anomalies with a high accuracy which is confirmed by our in situ surveys this paper is the first investigation on dozens of landsat satellite images to evaluate the state of coal fires within one year which is more accurate compared to previous approaches analyzing merely one or several satellite images to assess the state of coal fires during one year period

ejecta layer at the cretaceous tertiary boundary bass river new jersey ocean drilling program leg 174ax a continuously cored borehole drilled at bass river new jersey recovered a cretaceous tertiary k t succession with a 6 cm thick spherule layer immediately above the boundary below the spherule layer the cretaceous glauconitic clay is extensively burrowed and contains the uppermost maastrichtian micula prinsii calcareous nannofossil zone spherical impressions of spherules at the top of the cretaceous indicate nearly instantaneous deposition of ejecta from the chicxulub impact the thickest ejecta layer shows clearly that a single impact occurred precisely at k t boundary time above the spherule layer the glauconitic clay contains the planktonic foraminiferal p0 and p alpha zones indicating 1 a complete k t succession and 2 continuous deposition interrupted only by fallout of the ejecta layer clay clasts within a 6 cm interval above the spherule layer contain cretaceous microfossils and may be rip up clasts from a tsunami or possibly a megastorm event extinction of the cretaceous planktonic foraminifers and burrowing organisms occurs abruptly at the k t boundary thus the bass river k t succession unequivocally links the chicxulub bolide impact to the mass extinctions at the end of the mesozoic

proximal impact deposits at the cretaceous tertiary boundary in the gulf of mexico a restudy of dsdp leg 77 sites 536 and 540 restudy of deep sea drilling project sites 536 and 540 in the southeast gulf of mexico gives evidence for a giant wave at cretaceous tertiary boundary time five units are recognized 1 cenomanian limestone underlies a hiatus in which the five highest cretaceous stages are missing possibly because of catastrophic k t erosion 2 pebbly mudstone 45 m thick represents a submarine landslide possibly of k t age 3 current bedded sandstone more than 2 5 m thick contains anomalous iridium tektite glass and shocked quartz it is interpreted as ejecta from a nearby impact crater reworked on the deep sea floor by the resulting tsunami 4 a 50 cm interval of calcareous mudstone containing small cretaceous planktic foraminifera and the ir peak is interpreted as the silt size fraction of the cretaceous material suspended by the impact generated wave 5 calcareous mudstone with basal tertiary forams and the uppermost tail of the ir anomaly overlies the disturbed interval dating the impact and wave event as k t boundary age like beloc in haiti and mimbral in mexico sites 536 and 540 are consistent with a large k t age impact at the nearby chicxulub crater

palynology palynofacies and taphonomical studies of kamthi formation godavari graben southern india implications to biostratigraphy palaeoecology and depositional environment abstract the ambiguity regarding the age and palaeoecology of the kamthi formation is persisting for several years in order to find the scientific answers to this problem an integrated approach has been adopted on the samples collected from a 604 m thick sedimentary sequence borehole of the kamthi formation late permian godavari graben the compilation of detailed investigation includes the palynology palynofacies and taphonomic studies in order to establish the age reconstructing the palaeoecology and inferring the environment of deposition the palynological investigation indicates the presence of two informal palynoassemblages the lower palynoassemblage a faunipollenites striasulcites corresponds to the coarse grained sandstone dominated basal part and the palynoassemblage b densipollenites striate bisaccates occur in the upper fine grained sandstone and shale dominated sequence a detailed gondwanan correlation of the palynoassemblages assign a late permian age to the palynoflora palynoassemblage a belongs to the guadalupian age while palynoassemblage b corresponds to the lopingian age the dominance of glossopterids peltasperms conifers and cordaites derived pollens indicate the presence of thick arborescent palaeovegetation the rich cryptogam spore assemblage algal fillicopsid and equisetopsid constitute the opportunistic and rare component of the understorey flora the present study suggests that the lycopsids along with few acritarchs make their appearance post guadalupian the taphonomic studies infer that the palynoassemblages are greatly influenced by the structure of spores and pollen saccus further the palynofacies analysis reveals a cyclic change in the environment fluctuating from unstable oxic to the stable anoxic environment the occurrence of microscopic charcoal from the late permian also suggests palaeo wildfire events in the hinterland

chicxulub crater yucatan tektites impact glasses and the geochemistry of target rocks and breccias a comparison of breccias and basement rocks from four drill holes near the chicxulub impact structure yucatan a possible cretaceous tertiary k t boundary crater with black and yellow impact glasses from the haitian k t boundary layer shows that mixtures of andesite like rocks with carbonates and evaporites from chicxulub are compositionally different from the yellow glasses at the time of impact the chicxulub area was covered by evaporitic and carbonate deposits several kilometres thick because impact glasses are generally produced by shock melting of surface rocks a link between the haitian glasses and chicxulub is difficult to understand the 34 s isotopic signature of chicxulub breccias and evaporites is incompatible with that of a continental k t boundary we suggest that the pre impact target stratigraphy at chicxulub as well as the interpretation of the carbonate evaporite rocks as breccias should be revised

emplacement of cretaceous tertiary boundary shocked quartz from chicxulub crater observations on shocked quartz in cretaceous tertiary k t boundary sediments compellingly tied to chicxulub crater raise three problems first in north america shocked quartz occurs above the main k t ejecta layer second shocked quartz is more abundant west than east of chicxulub third shocked quartz reached distances requiring initial velocities up to 8 kilometers per second corresponding to shock pressures that would produce melt not the moderate pressure shock lamellae observed shock devolatilization and the expansion of carbon dioxide and water from impacted wet carbonate producing a warm accelerating fireball after the initial hot fireball of silicate vapor may explain all three problems

assessing and calibrating the atr ftir approach as a carbonate rock characterization tool abstract atr ftir attenuated total reflectance fourier transform infrared spectroscopy can be used as a rapid and economical tool for qualitative identification of carbonates calcium sulphates oxides and silicates as well as quantitatively estimating the concentration of minerals over 200 powdered samples with known concentrations of two three four and five phase mixtures were made then a suite of calibration curves were derived that can be used to quantify the minerals the calibration curves in this study have an r2 that range from 0 93 0 99 a rmse root mean square error of 1 5 wt and a maximum error of 3 10 wt the calibration curves were used on 35 geological samples that have previously been studied using xrd x ray diffraction the identification of the minerals using atr ftir is comparable with xrd and the quantitative results have a rmsd root mean square deviation of 14 and 12 for calcite and dolomite respectively when compared to xrd results atr ftir is a rapid technique identification and quantification takes

mercury emissions from dynamic monitoring holes of underground coal fires in the wuda coalfield inner mongolia china abstract the wuda coalfield inner mongolia china is one of the largest coalfields suffering from coal fires in china and has experienced fires for 50 years with the aim of observing the active state of underground coal seam fires to protect the main roadways of the coal mine 44 drill holes were drilled in five fire areas of the suhaitu coal mine to monitor gas emissions a lumexra 915 portable mercury analyzer was used to measure mercury concentrations in the exhaust gas the drill holes exhibited high gaseous mercury concentrations with an average of 4165 ng m 3 34 62 513 ng m 3 n 1584 which was 45 times higher than that measured in the near surface atmosphere around the drill holes this finding indicates that the mercury emissions originate from underground coal fires furthermore mercury concentration has a positive correlation with co content and gas temperature implying that mercury has the potential to act as a supplementary coal fire index gases to monitor the prevailing underground coal fire in north china on the basis of traditional indicators whether it can perform satisfactorily in practical applications requires further comprehensive study

extra basinal fluid infiltration mass transfer and volume strain during folding insights from the idaho montana thrust belt finite strain and geochemical variations along strain gradients were used to study cleavage development in carbonates in the lost river range idaho deformation accommodating layer parallel shear was partitioned into thin deforma tion zones during folding of willow creek anticline cleavage intensity is strong to very strong in deformation zones and weak in surrounding rocks strain magnitudes range from e s0 32 1 15 0 93 0 73 x y z principal axes of strain outside to e s0 64 1 29 0 80 0 52 inside deformation zones we found a positive linear correlation between strain cleavage development and negative dilation volume loss at a cubic centimeter scale ranges from 12 percent to 49 percent cleavage selvages are depleted in ca and 18 o and enriched in other elements relative to microlithons and less deformed protolith carbonates mass balance considerations indicate that cleavage was formed by incongruent pressure solution leading to a passive concentration of less soluble components during ca loss and metasomatic additions of si al and k to produce authigenic clay minerals in selvages data for the willow creek locality and elsewhere in the lost river range davidson and others 1998 pioneer mountains and the tendoy range bebout and others 2001 show that across the sevier orogen fluid infiltration was heterogeneous at centimeter kilometer scales and resulted from positive feedback between deforma tion and far traveled surficial fluids metasomatic strain softening enhanced deforma tion zone development which generated increased permeability as the thrust belt evolved from a porosity based closed system to a discontinuity based open system increased fluid infiltration and isotopic exchange was associated with volume loss increasingly prolate strains and crystallization of clays to produce the cleavage selvages mass transfer was accommodated by diffusion early and advection later in the deformation history mesoscopic structures deformation zones faults veins focused fluid flow and were kinematically related to larger scale structures faults fault related folds the inferred addition of surficial fluids to depths of 7 kilometers in the thrust belt implies a fluid regime involving significant topographically driven recharge deformed whole rocks and microsamples are lower in 18 o than unde formed samples which have o and c isotope compositions similar to those of marine carbonates veins are even lower in 18 ov smow with minimum values of 5 permil reflecting penetration of the crust by ocean derived precipitation with 18 o near to somewhat lower than 0 permil range of 7 5 to 2 5 calculated for h2 oi n equilibrium with these veins the inferred penetration into the thrust belt of nearshore meteoric waters is consistent with proximity to the reconstructed western interior seaway later fluid infiltration locally lowered the 18 o of carbonates even further based on the o isotope compositions of veins related to younger compres sional deformation and to the onset of crustal scale extension in the eocene this progression toward lowered 18 o of the surficial waters is compatible with the retreat of the seaway during emergence of the thrust wedge and paleogene extension uplift and subaerial volcanism

synchroneity of the k t oceanic mass extinction and meteorite impact blake nose western north atlantic a 10 cm thick layer of green spherules occurs precisely at the biostratigraphic boundary between the cretaceous and paleogene k t boundary at ocean drilling program site 1049 lat 30 08 n long 76 06 w the spherulitic layer contains abundant rock fragments chalk limestone dolomite chert mica books and schist as well as shocked quartz abundant large cretaceous planktic foraminifera and rounded clasts of clay as long as 4 mm interpreted as altered tektite glass probably derived from the chicxulub impact structure most of the cretaceous foraminifera present above the spherule layer are not survivors since small specimens are conspicuously rare compared to large individuals instead the cretaceous taxa in paleocene sediments are thought to be reworked the first paleocene planktic foraminifera and calcareous nannofossil species are recorded immediately above the spherule bed the upper part of which contains an iridium anomaly hence deposition of the impact ejecta exactly coincided with the biostratigraphic k t boundary and demonstrates that the impact event was synchronous with the evolutionary turnover in the oceans these results are consistent with a reanalysis of the biostratigraphy of the k t boundary stratotype which argues that shallow marine k t boundary sections are not biostratigraphically more complete than deep sea k t boundary sites

the impact of the cretaceous tertiary bolide on evaporite terrane and generation of major sulfuric acid aerosol abstract impact glasses from the k t boundary in haiti include high ca glasses with up to 1 wt so3 formed by the fusion of anhydrite or gypsum rich evaporite sediments in the presence of high silica melts derived from melting of continental crust experimental studies have duplicated these two melts by fusion of gypsum and andesite and suggest a formation temperature of 1300 c geochemical evidence from the glasses is consistent with their derivation from the 180 km diameter chicxulub impact crater on the yucatan peninsula mexico situated in a thick late cretaceous evaporite succession this large diameter crater is most likely the result of a cometary impact on the basis of bolide scaling from the ir anomaly in k t boundary sediments the sulfur degassing associated with formation of the high ca glass alone could have formed a2 1016 g h2so4 stratospheric aerosol however the total sulfur degassing from the evaporite rich sediments in the chicxulub impact site may have led to formation of3 8 1018 to1 3 1019 g sulfate aerosol and global atmospheric mass loading from the sulfate aerosol alone is estimated to beof the order of 1 2 6 g cm 2 combined with the great optical depth estimates of pollack et al 1 and covey et al 2 resulting from an impact dust cloud the sulfate aerosol may have contributed not only to a rapid decline in global surface temperatures to near freezing in about one week but also prolonged the cooling for several years because of the time dependent conversion of so2 to h2so4 aerosol in the atmosphere the contribution of sulfur to acid rain following the k t boundary event may have equalled the proposed rainout of nitric acid

zeolitization of volcaniclastic sediments the role of temperature and ph abstract this paper addresses the question of why some volcanic ashes are zeolitized and others are not the ph of interstitial water is the most important control on zeolitization surface water and groundwater in volcanic areas is acidic but zeolitization requires neutral to alkaline conditions therefore acidic interstitial water must be removed or neutralized before zeolitization can take place conditions favoring zeolitization are deposition or redeposition under water or reheating of ash after acidic interstitial water has been removed or influx of slightly alkaline bicarbonate bearing groundwater from overlying or neighboring limestones

coal fires revisited the wuda coal field in the aftermath of extensive coal fire research and accelerating extinguishing activities abstract the wuda coal mining area in inner mongolia autonomous region china is one of the largest coal fire areas world wide at the same time it is also one of the most extensively researched ones the sub surface coal fires raging in the underground coal seams of the syncline are located directly west of the town of wuda the fires have been mapped in situ based on remote sensing data as well as based on geo physical survey all throughout the years 2001 to 2005 numerous publications depict the situation during that time in the present study we assess the current situation in wuda coal field five years after the last field campaigns under nowadays on going and accelerating extinguishing activities we present the results of coal fire dynamics assessment based on in situ mappings between 2004 and 2010 the analyses of changes in mining infrastructure between 2005 and 2012 as well as land cover change in the area from 2005 to 2012 newest high resolution multispectral and panchromatic quickbird data as well as time series of quickbird data supported this endeavor we furthermore present the result of semi structured interviews undertaken with members of the local mine directorate of the wuda syncline all jointly analyzed data indicate that the wuda coal fires tend to move eastwards within the syncline meaning that they move along the dip of the coal seams to greater depths furthermore mining related infrastructure is clearly moving from the west to the east as well despite large funds spent on fire extinguishing only few fires remain permanently extinct while other fire areas increase in size the former land cover structure in the arid syncline does not exist anymore extinguishing activities have led to a complete turn over of all material in the region the coal fire problem in wuda area remains a pressing one

mercury enrichments provide evidence of early triassic volcanism following the end permian mass extinction abstract oceanic environments and biotas were in a state of near continuous perturbation during the early triassic the 5 million year interval following the latest permian mass extinction lpme but the underlying cause s remain uncertain the role of episodic volcanic or intrusive magmatic activity in triggering global scale perturbations during this interval is suspected but has not been strongly evidenced to date here we investigate the record of volcanism through the early triassic with a focus on the smithian spathian boundary or ssb using mercury hg concentrations in marine sediments as a proxy this study examines five marine sections from three paleo oceans paleo tethys neo tethys and panthalassa representing a range of depositional settings from shallow platform to deep slope our results suggest that volcanic and magmatic activity of the siberian traps large igneous province stlip was most intense during the first 1 3 million years following the lpme and that termination of its most active stage was responsible for a sharp cooling event at the ssb variations in the intensity of stlip activity are thus likely to account for the large 8 fluctuations of 13ccarb and related changes in oceanic redox and environmental conditions that characterized the griesbachian to smithian substages of the early triassic in marine sections globally we hypothesize that a strong reduction or cessation of stlip activity at the ssb set the stage for the recovery of marine biodiversity and ecosystems in the spathian and later

coeval 40ar 39ar ages of 65 0 million years ago from chicxulub crater melt rock and cretaceous tertiary boundary tektites 40 ar 39 ar dating of drill core samples of a glassy melt rock recovered from beneath a massive impact breccia contained within the 180 kilometer subsurface chicxulub crater in yucatan mexico has yielded well behaved incremental heating spectra with a mean plateau age of 64 98 0 05 million years ago ma the glassy melt rock of andesitic composition was obtained from core 9 1390 to 1393 meters in the chicxulub 1 well the age of the melt rock is virtually indistinguishable from 40 ar 39 ar ages obtained on tektite glass from beloc haiti and arroyo el mimbral northeastern mexico of 65 01 0 08 ma mean plateau age for beloc and 65 07 0 10 ma mean total fusion age for both sites the 40 ar 39 ar ages in conjunction with geochemical and petrological similarities strengthen the recent suggestion that the chicxulub structure is the source for the haitian and mexican tektites and is a viable candidate for the cretaceous tertiary boundary impact site

seawater sr isotopes at the cretaceous tertiary boundary abstract seawater 87 sr 86 sr values increase abruptly by 28 10 6 across the cretaceous tertiary boundary ktb this small but rapid shift is superimposed on the larger scale structure of the seawater sr isotope curve the time scale of radiogenic sr addition appears to be too rapid to reconcile with sources associated with volcanism and we show that the amount of sr required to produce even this small increase is too large to be derived from 1 a kt bolide of the size constrained by the ir anomaly 2 continental crust ejecta from the impact of such a bolide 3 soot from global wildfires initiated by an impact or 4 any combination of these sources the probable source of the radiogenic sr is enhanced continental weathering but the high rate of increase appears to rule out processes such as sea level regression glaciation or tectonism a plausible mechanism for rapid addition of radiogenic sr to the oceans is enhanced weathering associated with globally distributed acid rain ph 1 which is a proposed by product of a bolide impact 51 epsl vol 83

three dimensional strain produced by 50 my of episodic extension horse prairie basin area sw montana u s a abstract the horse prairie basin of southwestern montana is a complex east dipping half graben that contains three angular unconformity bounded sequences of tertiary sedimentary rocks overlying middle eocene volcanic rocks new mapping of the basin and its hanging wall indicate that five temporally and geometrically distinct phases of normal faulting and at least three generations of fault related extensional folding affected the area during the late mesozoic to cenozoic all of these phases of extension are evident over regional or cordilleran scale domains the extension direction has rotated 90 four times in the horse prairie area resulting in a complex three dimensional strain field with 60 east west and 25 north south bulk extension extensional folds with axes at high angles to the associated normal fault record most of the three dimensional strain during individual phases of extension phases 3a 3b and 4 cross cutting relationships between normal faults and tertiary volcanic and sedimentary rocks constrain the ages of each distinct phase of deformation and show that extension continued episodically for more than 50 my gravitational collapse of the sevier fold and thrust belt was the ultimate cause of most of the extension

mass wasting and hiatuses during the cretaceous tertiary transition in the north atlantic relationship to the chicxulub impact deep sea sections in the north atlantic are claimed to contain the most complete sedimentary records and ultimate proof that the chicxulub impact is cretaceous tertiary boundary ktb in age and caused the mass extinction a multi disciplinary study of north atlantic dsdp sites 384 386 and 398 based on high resolution planktonic foraminiferal biostratigraphy carbon and oxygen stable isotopes clay and whole rock mineralogy and granulometry reveals the age stratigraphic completeness and nature of sedimentary disturbances results show a major hiatus across the ktb at site 384 with zones cf1 p0 and p1a missing spanning at least 540 ky similar to other north atlantic and caribbean localities associated with tectonic activity and gulf stream erosion at sites 386 and 398 discrete intervals of disturbed sediments with mm to cm thick spherule layers have previously been interpreted as the result of impact generated earthquakes at the ktb destabilizing continental margins prior to settling of impact spherules however improved age control based on planktonic foraminifera indicates spherule deposition in the early danian zone p1a 2 upper parvularugoglobigerina eugubina zone more than 100 ky after the ktb at site 386 two intervals of white chalk contain very small 63 m early danian zone p1a 2 assemblages 65 and common reworked cretaceous 35 species in contrast the in situ red brown and green abyssal clays of this core are devoid of carbonate in addition high calcite mica and kaolinite and upward fining are observed in the chalks indicating downslope transport from shallow waters and sediment winnowing via distal turbidites at site 398 convoluted red to tan sediments with early danian and reworked cretaceous species represent slumping of shallow water sediments as suggested by dominance of mica and low smectite compared to in situ deposition we conclude that mass wasting was likely the result of earthquakes associated with increased tectonic activity in the caribbean and the iberian peninsula during the early danian well after the chicxulub impact

geomorphology of coal seam fires abstract coal fires occur in underground natural coal seams in exposed surface seams and in coal storage or waste piles the fires ignite through spontaneous combustion or natural or anthropogenic causes they are reported from china india usa south africa australia and russia as well as many other countries coal fires lead to loss of a valuable resource coal the emission of greenhouse relevant and toxic gases and vegetation deterioration a dangerous aspect of the fires is the threat to local mines industries and settlements through the volume loss underground surface collapse in coal fire areas is common thus coal fires are significantly affecting the evolution of the landscape based on more than a decade of experience with in situ mapping of coal fire areas worldwide a general classification system for coal fires is presented furthermore coal seam fire geomorphology is explained in detail the major landforms associated with and induced by these fires are presented the landforms include manifestations resulting from bedrock surface fracturing such as fissures cracks funnels vents and sponges further manifestations resulting from surface bedrock subsidence include sinkholes trenches depressions partial surface subsidence large surface subsidence and slides additional geomorphologic coal fire manifestations include exposed ash layers pyrometamorphic rocks and fumarolic minerals the origin evolution and possible future development of these features are explained and examples from in situ surveys as well as from high resolution satellite data analyses are presented the geomorphology of coal fires has not been presented in a systematic manner knowledge of coal fire geomorphology enables the detection of underground coal fires based on distinct surface manifestations furthermore it allows judgments about the safety of coal fire affected terrain additionally geomorphologic features are indicators of the burning stage of fires finally coal fire geomorphology helps to explain landscape features whose occurrence would otherwise not be understood although coal fire induced thermal anomalies and gas release are also indications of coal fire activity as addressed by many investigators no assessment is complete without sound geomorphologic mapping of the fire induced geomorphologic features

cretaceous tertiary chicxulub impact angle and its consequences the chicxulub impact structure exhibits asymmetries in its geophysical signatures that closely resemble asymmetries produced by oblique impacts in laboratory experiments and recognized on planetary surfaces these asymmetric signatures suggest a trajectory for the chicxulub bolide from the southeast to the northwest at a 20 30 angle from the horizontal as a result biotic extinctions may have been most severe and catastrophic in the northern hemisphere geographic variation in the magnitude of the cretaceous tertiary k t fern spike and palynofloral extinctions are consistent with the proposed trajectory

quench textures in altered spherules from the cretaceous tertiary boundary layer at agost and caravaca se spain abstract abundant spherules are observed in a well preserved cretaceous tertiary boundary ktb layer at the agost and caravaca sections betic cordilleras se spain these spherules have been diagenetically altered to goethite or k feldspar different morphologies are observed ranging from perfect spheres to droplet shapes this is the first time that dendritic and fibroradial textures are reported in goethite spherules with clearly splash form morphology this morphology suggests that they originated from melt in the hot vapour plume and not as condensate as unaltered ktb spherules are composed of clinopyroxene this could be the probable precursor of part of the altered spherules at agost and caravaca which may have been derived from an expanding vapour plume with a significant contribution of extraterrestrial material in addition c rich cores have been detected in k feldspar which are enriched in ir pt pd and ni although postdepositional processes and microbial activity could have led to severe modification of the original element concentrations the high content of noble metals and ni suggests extraterrestrial contamination

geochemistry of impact glasses from the k t boundary in haiti relation to smectites and a new type of glass we have individually analyzed twelve black and seven yellow glasses from the k t boundary section at beloc haiti plus three smectite mantles around black glasses the main chemical differences between black and yellow glasses are higher s ca mg zn as br sb and au but lower k na and si abundances in the yellow glasses we have found high cao yellow glasses with low s contents 0 08 0 17 wt which may be explained by fusion of carbonate rich sediments microprobe studies of individual glasses show that the black glasses are very homogeneous in their composition at the 10 100 m level while yellow glasses show much more variability and different intra sample elemental correlations one of the black glasses has higher sio2 and k2o abundances but lower concentrations of all other major elements this suggests the existence of a third glass type which we have named the high si k variety hsi k glass the glass shows areas consisting of pure sio2 maybe lechatelierite and some schlieren with lower sio2 content the chemical composition indicates that the hsi k glass may have originated from melting of a sedimentary source rock such as shale or argillite severe changes in major and trace element composition occur during alteration of the glass as documented by analyses of adhering smectites the ree patterns in the glass are similar to average upper crust but the smectites exhibit much lower abundances and flat patterns not unlike the patterns observed in claystones at numerous k t boundary sites the suggestion that the chicxulub structure in yucatan may be the source crater for the k t impact glasses is not fully supported by the currently available data impact glasses and tektites are produced from the surface layers of their targets at chicxulub the target stratigraphy comprised mainly carbonates and evaporites although we cannot exclude chicxulub as a source the present data do not provide any firm chemical evidence for a connection we conclude however that the haiti glasses have formed by impact and have later undergone alteration by low temperature hydrothermal processes to produce clays the boundary claystones at k t boundary sites may very well be alteration products of these impact glasses

tektite bearing deep water clastic unit at the cretaceous tertiary boundary in northeastern mexico the hypothesis of cretaceous tertiary k t boundary impact on yucatan mexico predicts that nearby sites should show evidence of proximal impact ejecta and disturbance by giant waves an outcrop along the arroyo el mimbral in northeastern mexico contains a layered clastic unit up to 3 m thick that interrupts a biostratigraphically complete pelagic marl sequence deposited at more than 400 m water depth the marls were found to be unsuitable for determining magnetostratigraphy but foraminiferal biostratigraphy places the clastic unit precisely at the k t boundary we interpret this clastic unit as the deposit of a megawave or tsunami produced by an extraterrestrial impact the elastic unit comprises three main subunits 1 the basal spherule bed contains glass in the form of tektites and microtektites glass spherules replaced by chlorite smectite and calcite and quartz grains showing probable shock features this bed is interpreted as a channelized deposit of proximal ejects 2 a set of lenticular massive graded laminated beds contains intraclasts and abundant plant debris and may be the result of megawave backwash that carried coarse debris from shallow parts of the continental margin into deeper water 3 at the top several thin ripple beds composed of fine sand are separated by clay drapes they are interpreted as deposits of oscillating currents perhaps a seiche an iridium anomaly 921 23 pg g is observed at the top of the ripple beds our observations at the mimbral locality support the hypothesis of a k t impact on nearby yucatan

basement and cover rock deformation during laramide contraction in the northern madison range montana and its influence on cenozoic basin formation two major laramide fault systems converge in the northwestern madison range the northwest striking southwest vergent spanish peaks reverse fault and the north striking east vergent hilgard thrust system analysis of foliation attitudes in basement gneiss north and south of the spanish peaks fault indicates that the basement in thrusted blocks of the hilgard thrust system has been rotated by an amount similar to that of the basement cover contact steeply dipping north striking breccia zones enclosing domains of relatively undeformed basement may have permitted domino style rotation of basement blocks during simple shear between pairs of thrusts in most places along the hilgard thrust system a large basement overhang produced by thrusting of archean blocks above rocks as young as late cretaceous overlies a tight footwall syncline this tight folding is largely concentric and was accommodated by flexural slip resulting in severe crowding in synclinal hinges that resulted in observed or inferred features such as bedding plane slip imbricate and out of syncline thrusting and hinge collapse the north striking madison normal fault system a zone of tertiary and quaternary valley forming normal faults is approximately parallel to the hilgard thrust system in some places normal faults are reactivated thrusts on which large basement overhangs of the hilgard thrust system were dropped back into the madison valley and covered by tertiary basin fill deposits leaving only the rocks of the footwall synclines exposed in other places both the thrusted archean blocks and the near isoclinal footwall synclines are well preserved this paired fault system the madison normal fault system and the hilgard thrust system of the northern madison range is strikingly similar to other paired systems in southwestern montana along and adjacent to the western margins of the ruby range snowcrest range greenhorn range tobacco root mountains and bridger range such systems may be the result of collapse of the crestal zones of large laramide basement uplifts arches during tertiary extension no hydrocarbon discoveries have been made in this unique structural province however petroleum exploration here has focused on basement cored anticlines both surface and subthrust related to the two major laramide fault systems and on the fault bounded blocks of tertiary rocks within the post laramide extensional basins the interplay of the two laramide fault systems during both laramide shortening and tertiary extension has produced a variety of possible structural traps in the madison range that have not yet been thoroughly investigated

isotopic comparison of k t boundary impact glass with melt rock from the chicxulub and manson impact structures the discussion of candidate source craters for the catastrophic impact that occurred at the boundary between the cretaceous and tertiary periods k t boundary has recently centred on two buried craters the chicxulub in mexico 200 km diameter and the manson in iowa 35 km diameter both of which have 40ar 39ar ages of 65 myr indistinguishable from that of impact glass spherules found in k t boundary sediments1 4 here we report the strontium neodymium and oxygen isotopic compositions of core samples of impact melt rock recovered from drill holes into both the chicxulub and manson craters and compare these with previously published isotopic data for impact glasses from the k t boundary of the beloc formation in haiti5 7 the chicxulub melt rocks are isotopically indistinguishable from the k t impact glass strongly supporting the proposition that chicxulub is a source crater for the k t catastrophe the manson melt rocks by contrast have a clearly different isotopic composition strongly suggesting that they are unrelated to the k t impact spherules