the euramerican coal province controls on late paleozoic peat accumulation abstract the ancestral tropical peats and associated strata of the euramerican coal province record the interwoven effects of climate tectonism and eustasy during the late paleozoic many peats formed in foreland and intermontane basins associated with equatorial orogenic belts along the borderlands of euramerica and gondwana while other peats formed in adjacent cratonic basins the resolution of controls on euramerican peat formation requires testing against a well constrained temporal framework the late paleozoic coal age followed the evolution of vascular plants in the late silurian and was associated with assemblage of the pangean supercontinent devonian and early carboniferous peats developed locally the major phase of peat formation commenced in the namurian a and persisted to the end of the stephanian spanning 10 30 ma in different regions of euramerica it is ascribed in part to the residence of northward drifting euramerica within the equatorial rainy belt within individual depocenters basin hydrology was suitable for peatland formation during a period 10 6 10 7 years represented by the stratigraphic distribution of coal measures and termed here the basin fill coal window repeated successions cyclothems of coal siliciclastic and carbonate strata punctuate the coal window and typically represent 10 4 10 5 years these stratal successions are widely ascribed to orbitally driven glacioeustasy although cyclothems that lack marine strata may represent associated climatic shifts cyclothem groupings mesothems of 10 6 years duration are recognised locally and may have eustatic or tectonic causes cyclothems produced by autocyclic events such as delta switching should have durations in the order of 10 3 years the coal beds themselves represent autogenic processes of peat formation over periods of 10 3 10 4 years constrained by longer term allogenic effects recorded in the coal bed are tolerable allogenic events such as fires and floods caused by short term climatic excursions the termination of most mires probably occurred when single or combined allogenic effects surpassed the inherent ability of the ecosystem to adapt

geological implications of the 0212 earthquake in 2014 at the tatun volcano group of taiwan synergistic effects of volcanic and faulting activities abstract on february 12 2014 an ml 4 2 earthquake named 0212 eq occurred at the tatun volcano group tvg in northern taiwan seismic data from both the regional broadband array in taiwan and a local dense seismic network in the tvg indicate that the 0212 eq was located at a depth of 4 3 km near shamoshan one of the latest eruptive units in the tvg referring to the aftershocks surrounding the 0212 eq we further found that 1 they formed a linear seismic zone dipping 50 towards the southeast to reach the shanchiao fault that cuts through the tvg 2 focal mechanism of more than half of the larger aftershocks md 1 5 matched this linear seismic zone for a normal faulting and 3 the seismic b value was calculated to be 3 55 they are used to delineate the geometry of the shanchiao fault at the upper crust and to infer that localized geothermal fluid might have affected the activity of aftershocks as manifested by the very high seismic b value the strongly compensated linear vector dipole of the centroid moment tensor suggests the 0212 eq had a non double couple source resulted from the gravitational collapse thus we conclude that the 0212 eq was a combined synergistic effect of a collapsed reservoir filled with volcanic fluids and faulting activities along the shanchiao fault

crustal and upper mantle s wave velocity structures across the taiwan strait from ambient seismic noise and teleseismic rayleigh wave analyses abstract although orogeny tapers off in western taiwan large and small earthquakes do occur in the taiwan strait a region largely untouched in previous studies owing mostly to logistical reasons but the overall crustal structure of this region is of particular interest as it may provide a hint of the proto taiwan before the orogeny by combining time domain empirical green s function tdegf from ambient seismic noise using station pairs and traditional surface wave two station method ts we are able to construct rayleigh wave phase velocity dispersion curves between 5 and 120 s using broadband array in taiwan for seismology bats stations in taiwan and in and across the strait we are able to derive average 1 d vs structures in different parts of this region the results show significant shear velocity differences in the upper 15 km crust as expected in general the highest vs in the upper crust observed in the coastal area of mainland china and the lowest vs appears along the southwest offshore of the taiwan island they differ by about 0 6 1 1 km s for different parts of the strait the upper crust vs structures are lower in the middle by about 0 1 0 2 km s relative to those in the northern and southern parts the upper mantle vs structure moho 150 km beneath the taiwan strait is about 0 1 0 3 km s lower than the ak135 model the overall crustal thickness is approximately 30 km much thinner and less variable than under the taiwan island the inversion of seismic velocity structures using shorter period band dispersion data in the sea areas with water depth deeper than 1000 m should take water layer into consideration except for the continental shelves

characterization of an internal slope movement structure by hydrogeophysical surveying a hydrogeophysical study was carried out by a water controlled injection within a landslide situated on an active part of the la clapiere landslide foot alpes maritimes france coupling of both real time geophysical and hydrological follow ups allowed the representation and quantification of the surface water drainage in space and time within the slipped mass thus 30 of the injected water is quickly drained by a complex slipping surface meanly situated at 10 m depth the transit time between injection and outflow of the water allowed an overloading of about 10 m3 i e 10 tons comparable with classical rain events in the area this weight and the associated interstitial pressures increase have not led to any movements asking for the origin of the water volumes which could induce destabilizations this experiment enabled an accurate redefinition of the internal slope structure and the understanding of the dynamics of the slipped mass with a surface hydraulic request

modern estuarine siliceous spiculites tasmania australia a non polar link to phanerozoic spiculitic cherts biosiliceous sedimentary rocks are well known from the geologic record and many are correctly interpreted to have formed in deep water or cold water environments shallow non polar spiculites are also known from the rock record yet no modern analog has been documented for such environments bathurst harbour an estuarine system in southwest tasmania provides this much needed modern analog in this system a sharp halocline separates tannin rich low salinity surface waters from clear marine bottom waters tannins supply few nutrients and substantially reduce light penetration to bottom environments resulting in a thinned photic zone and the mixing of deeper water sub photic biotas of soft corals bryozoans and sponges with other organisms more typical of this temperate shallow water environment the well defined halocline allows a typically marine biota including echinoderms to live in bottom waters of this estuarine setting the bioclastic factory producing both carbonate and siliceous particles exists in marine subphotic bottom waters of incised channel and shallow rocky environments along the shoreline extensive organic rich soft sediments in protected embayments generate few bioclasts but contain allochthonous sponge spicules transported from the adjacent bioclastic factory trapping of organic material within the estuarine system lowers sediment ph and promotes dissolution of carbonate biofragments resulting in preferential preservation of siliceous sponge spicules this situation implies that many biosiliceous neritic deposits in the rock record may be the result of similar preferential preservation

the occurrence and significance of biogenic opal in the regolith abstract biogenic opal produced by vascular plants diatoms and siliceous sponges have been found in soils and terrestrial sediments of all continents except antarctica since the middle of the 19th century the opal particles range in size from fine silt to fine sand almost all soils contain detectable opal up to levels of 2 3 and a significant number contain values in excess of 5 even higher values have been found from soils and sediments of all continents in a wide range of soil types the most important factor is poor soil drainage and seasonal to permanent water logging this encourages the proliferation of silica producing organisms such conditions have been found in the soils and aquatic sediments of the monsoonal tropics tropical rain forests temperate forests tropical savanna tropical islands semi arid grasslands and savanna and temperate woodland and grassland the presence of a volcanic substrate also appears favourable in some cases but is not necessary biogenic opal preferentially collects in the a horizon of soils and to a lesser extent in the b horizon this preferential distribution facilitates identification of palaeosols in stacked soil sequences biogenic opal is also a component of windblown dust even in arid environments biogenic opal is significant to regolith processes in a number of ways firstly as in the case in marine environments it is likely to be important in silica cycling and storage because of its greater lability compared to quartz secondly dissolution and reprecipitation of opal a as opal ct or micro quartz may play a role in cementation and silicification of regolith to form silica hardpans and silcrete thirdly the organisms that form biogenic opal can have considerable palaeoenvironmental significance and be valuable in reconstructing regolith evolution finally some forms of biogenic silica in particular sponge spicules can present a health hazard their high abundance in some soils and sediments needs to be considered when assessing the health implications of airborne dust

temporal variations of gas compositions of fumaroles in the tatun volcano group northern taiwan article i nfo he 4 he geochemical monitoring hydrothermal activity is common in the tatun volcano group of northern taiwan helium isotopic compositions of fumarolic samples show that mantle component occupies more than 60 in the previous study along with recent seismic results a magma reservoir is inferred to have existed beneath the area of da you keng where fumarolic venting is the most active in tatun volcano group progressive increases of hcl concentrations and so2 h2s ratio in fumaroles from da you keng have been observed since august 2004 the hcl concentration changed from almost the detection limit to thousands of ppm even up to 30 000 ppm so2 h2s ratios varied from almost 0 to 3 hence so2 became the dominated s species in this area these variations were accompanied by rising temperature of fumaroles in the tatun volcano group especially in the area of da you keng from boiling point to 131 c meanwhile 3

tornillos at vulcano clues to the dynamics of the hydrothermal system abstract the number of tornillo events has recently increased at the vulcano island italy while only 15 tornillos were recorded during 2004 2006 584 events occurred in 2007 2008 they were located just below la fossa crater at depths ranging between 0 1 and 1 km b s l during two intervals in 2007 2008 increases in the number of tornillos took place at the same time as temperature and geochemical anomalies were observed the spectral content of the tornillos generally characterized by one two dominant spectral peaks near 6 and 10 hz varied over time with changes also noted in the quality factors the simplest source mechanism proposed for tornillos is the free eigenvibration of a fluid volume within a crack or a conduit based on this model we propose a causal relationship between the temperature and geochemical anomalies and the increases in numbers of tornillos as the amount of hydrothermal fluids increases during the anomalies the upward flux of fluids grows the consequent changes in the pressure temperature and dynamics of the system of cracks and conduits result in the generation of tornillos based on the fluid filled crack conduit model the shallow depths of the sources and the values of the quality factors the fluid within the resonant crack conduit was inferred to be an ash gas or water droplet gas mixture moreover the observed variations in the wavefield can be caused by small changes in the location of the source in the source mechanism or in the medium in between the source and the seismic station finally another peculiar feature of tornillos is the amplitude modulation that can be explained as a result of a beating phenomenon

sorbing tracer experiments in a crystalline rock fracture at aspo sweden 2 transport model and effective parameter estimation 1 transport and retention of sorbing tracers in a single altered crystalline rock fracture on a 5 m scale is investigated we evaluate the results of a comprehensive field study referred to as

polygenetic history of paleosols in middle upper pennsylvanian cyclothems of the illinois basin u s a part ii integrating geomorphology climate and glacioeustasy abstract distinct lateral and stratigraphic trends in paleosol morphology and clay mineralogy in conjunction with the stable isotope composition of sub millimeter scale spherulitic siderite sphaerosiderite and flint clay kaolinite in middle upper pennsylvanian cyclic coal bearing strata of the illinois basin ib presented herein provide proxy records of middle late pennsylvanian equatorial terrestrial environments collectively these data provide a better understanding of the polygenetic history of ancient soils preserved in cyclic strata and indicate that low latitude pennsylvanian ib soil profiles were influenced by a combination of autogenic and allogenic controls lateral variations in paleosol morphology from the interior of the basin to the northern margin indicate that soil development was dominantly influenced by autogenic controls such as differences in local paleohydrology i e groundwater fluctuations and subsidence rates across the basin conversely allogenic controls i e glacioeustasy and climate are interpreted to be principally responsible for the preservation of features in gleyed protosols gleyed vertisols and gleyed calcic vertisols that occur in the interior of the ib these paleosols are characterized by a polygenetic development history that includes 1 an initial period of soil formation in well drained environments with seasonal wetting and drying of the profile followed by 2 a subsequent period of waterlogging and development of reducing conditions paleosols that lack evidence for extensive periods of waterlogging are restricted with the exception of two examples to the northern margin of the basin and they become abundant in the stratigraphic record near the middle upper pennsylvanian boundary uppermost desmoinesian the stratigraphic distribution of these paleosols in conjunction with a decrease in the relative abundance of kaolinite in the 2 m size fraction of ib paleosols near the desmoinesian missourian d m boundary is interpreted to reflect a shift in the overall low latitude regional climate to drier conditions the stable isotope compositions of sphaerosiderite and flint clay kaolinite in middle upper pennsylvanian strata of the ib provide an additional proxy record of past equatorial terrestrial environments and are used to constrain the magnitude of paleoclimate change across the d m moscovian kasimovian boundary sphaerosiderite 18ov pdb and 13cv pdb values range from 3 6 to 0 5 and 12 8 to 3 2 respectively in particular sphaerosiderite 18o values from the b horizons of paleosols display an approximate 1 5 shift across the d m boundary this stratigraphically short isotopic shift occurs across the d m boundary on the order of one cyclothem 400 kyr and is followed by a subsequent shift on the order of one cyclothem back to more positive siderite 18o values the average 18ov smow and dv smow values of kaolinite isolated from the 0 2 m size fraction of a latest desmoinesian flint clay breccia are 21 0 and 46 5 these values correspond to a latest desmoinesian crystallization temperature of 27 2 c and a meteoric water 18ov smow value of 3 1 combination of sphaerosiderite 18o values and co occurring flint clay kaolinite d and 18o values suggest a possible warming of up to 6 c across the d m boundary corresponding to an approximate temperature change of siderite crystallization from 27 to 33 c this temperature increase in conjunction with distinct stratigraphic trends in the clay mineralogy and morphology of ib paleosols is consistent with previous paleoclimate interpretations and it suggests that low latitude pennsylvanian paleoclimate became drier and warmer across the d m boundary

seismogenic stress field beneath the tatun volcano group northern taiwan article i nfo the tatun volcano group tvg represents the main volcanic center in northern taiwan and based on various observations it is considered a potentially active volcano tvg has been monitored since 2003 by a seismic network that consists of eight stations equipped with three component short period and broadband seismometers in this study we use waveform data of high frequency earthquakes in order to investigate the stress field orientation beneath the tvg area the focal mechanisms of 35 selected events have been derived using p wave polarities and amplitude ratios assuming a double couple source these fault plane solutions and various subsamples derived from them were subsequently inverted for the best fitting stress tensor using a linear inversion method the results show stress homogeneity beneath tvg for depths larger than 3 km while the stress tensor is characterized by a subvertical 1 and a subhorizontal nw se trending 3 axis consistent with the regional stress field in northern taiwan on the other hand chihsinshan which is an area of vigorous hydrothermal activity exhibits a localized stress field with horizontal nw se trending 3 axis and ne sw trending horizontal 1 such an axes orientation is likely to be causing opening of microcracks and thus favour the ascent and circulation of fluids in the upper crust shear wave splitting measurements seem to confirm these results showing fast polarization directions along nne ne subparallel to the main fracture system in tvg shear wave anisotropy averages about 2 9 and is probably caused by an anisotropic volume of fluid saturated cracks within the upper 2 5 km of the crust

preliminary analysis of volcanoseismic signals recorded at the tatun volcano group northern taiwan 1 the tatun volcano group lies at the northern tip of taiwan only 15 km north of the capital taipei a seismic array consisting of 5 stations equipped with both broadband and short period sensors was installed in 2003 in order to monitor the seismic activity of the area it recorded a variety of events including common volcano tectonic earthquakes and volcanoseismic signals like tornillos short duration monochromatic events 10 15 s and long duration spasmodic bursts 15 min an analysis of the complex frequencies of the tornillo monochromatic signals shows that q values are of the order of several hundreds based on the model of a fluid filled crack such q values can result from the oscillations of a crack containing a misty or dusty gas these observations put into doubt the long standing suggestion that the tatun volcanoes are extinct and prompt for a thorough assessment of the volcanic hazard for this area

very long period seismic signals at the tatun volcano group northern taiwan abstract very long period vlp seismic events have been detected in the tatun volcano group tvg located around the border between taipei city and new taipei city in northern taiwan in which has 7 million residents by using both analyses of particle motions and travel time delay one vlp volcanic earthquake s source is estimated to be at a shallow depth 800 m beneath mt chihsin which is the highest and youngest volcano in the tvg the significant variation of seismic energy at different azimuths provides strong evidence to distinguish a crack source from other kinds of sources such as a sphere vertical pipe or even double couple source this is further confirmed by synthetic modeling of the seismograms recorded at two stations as well as the compressional first motion at three seismic stations thus a deeper plumping system with high pressure fluid is required to generate the vlp signals and other volcanic earthquakes in the tvg combining this result with those of previous studies we conclude that the tvg might not be totally extinct and some further investigations must be carried out to improve understanding of the volcanic characteristics of the tvg

silica replaced oolites bedded shelf cherts and paleozoic changes in the silica cycle abstract oolites that were replaced by early diagenetic silica and were not reworked from their original depositional setting can serve as a useful tool to evaluate a previously suggested retreat of biosiliceous facies from peritidal environments to deeper water settings in the early paleozoic the silica replaced oolites suggest that the retreat was largely over by the middle ordovician which is consistent with emerging compilations of the spatial and temporal distribution ordovician cherts whether the retreat was a function of declining concentration of dissolved silica in shallow marine waters or of radiation of faunas from nearshore into offshore settings or some combination of both is an issue that may be clarified with improved resolution of the timing of the retreat a small upper carboniferous peak in silica replaced oolite abundance coincides with a minor rebound in shelf chert accumulation and the common presence of coastal flint deposits in upper carboniferous cyclothems suggesting that cherty facies returned to shallow water environments at this time

biogenic chert and the ordovician silica cycle abstract analysis of 161 nodular and bedded cherts shows that shallow water biosiliceous facies which were common in the lower ordovician had mostly retreated from peritidal lagoonal facies to deeper settings by the middle ordovician for decades this retreat was thought to have spanned the cambrian and ordovician periods our data suggest that the basinward shift may have taken approximately 2 14 m y in the late lower to early middle ordovician a likely cause for the departure of these often siliceous sponge cherts from shallow waters was depletion of shallow water dissolved silica dsi increased use of dsi by radiolarians may have commenced in the middle ordovician when radiolarians increased just as a pulse of radiolarite deposition began siliceous sponges may have been forced to relocate to deeper waters because radiolarians depleted shallow water dsi apparent low relative sea level in the middle ordovician may have hampered the formation and or preservation of shallow water cherts by reducing available shelf area to host such deposits however the resurgence of shelf chert in the upper ordovician while peritidal cherts remained virtually absent suggests that biology was critical to driving the basinward shift of cherty facies formation and preservation of abundant latest darriwilian through sandbian cherts may have been favored in deep water settings during a possible warming interval marked by sea level rise and extensive anoxia and euxinia that coincided with an ongoing decline in 87sr 86sr ratios and increased sea floor volcanic activity that probably enriched the dsi content of deep ocean waters ocean circulation associated with the onset of cooling in the katian may have optimized chert accumulation by stimulating surface water biosiliceous productivity before dsi rich chert preserving anoxic basins were ventilated as late ordovician glaciation intensified deep ocean ventilation by thermohaline sinking of oxygen rich waters probably decreased preservation potential of biosiliceous deposits while increasing oceanic recycling of silica

facies geometry and growth phases of the valdorria carbonate platform pennsylvanian northern spain the 14 km wide valdorria outcrop pennsylvanian northern spain is one of the few examples of entirely exposed flat topped and high relief carbonate platforms reported in the fossil rock record laterally and vertically traceable stratal patterns expose three phases of growth phase i is a 430 m thick platform to slope succession that prograded over 6 km and is dated as early bashkirian akavasian askynbashian phase ii aggraded and prograded exhibiting 180 m thickness of cyclical platform top deposits dated as late bashkirian asatauian phase iii is a mound shape structure that developed over the platform top of phase ii as a new phase of platform nucleation it is 535 m thick and 2 km wide and dated as late bashkirian asatauian transition interval the observed changes of growth styles during platform evolution from a prograding to an aggrading prograding system and a rapid aggradational phase are inferred to be controlled by flexural subsidence in the active cantabrian foreland basin at the variscan orogenic front the metre scale shallowing upward cycles of the platform top are most probably due to glacioeustasy as evidenced by well recorded subaerial exposure surfaces superimposed on subtidal deposits and by a stratal pattern recurrent in a short interval of about 160 kyr observations of outcropping bashkirian cyclothems in an isolated carbonate system devoid of siliciclastic input are relevant for a better understanding of the impact of high frequency sea level fluctuations on the carbonate factory moreover progradation of the platform margin during phase i reaches a rate of 2500 m myr and 1810 m myr during phase ii rates that are high when compared to other pennsylvanian examples the aggradation rate of 447 m myr calculated for late bashkirian transition interval phases i and ii uncorrected for compaction missing beats and erosion is uncommonly high in comparison to coeval pennsylvanian examples the platform exhibits a self nourishing prograding microbial boundstone dominated slope thus the slope shedding model applies well to valdorria however phase ii recorded eustatic variations able to inhibit the slope microbial boundstone factory during low sea level stands this is marked by common slope red stained breccias synchronous to platform top subaerial exposure phases contrarily periods of relative high sea level and rapid subsidence in phase iii registered a greater development of cemented microbial boundstone these observed partly opposing relationships of sea level stands shedding modes and slope architecture provide an improvement of the currently used slope shedding model the overall architecture of the valdorria outcrop compares well with that of other contemporaneous platforms such as sierra del cuera and bolshoi karatau valdorria shares the high relief and flat topped steep slopes cyclothemic patterns and occurrence of karst features with the pricaspian basin platforms tengiz karachaganak and kashagan with minor variations in facies distribution of the internal platform furthermore the continuous seismic scale outcrop of valdorria together with its isolated setting and asymmetrical growth makes it an additional good candidate for potential subsurface analogues of hydrocarbon bearing systems

the seismic velocity and attenuation structure beneath the tatun volcanic area taiwan abstract we have investigated the structure beneath the tatun volcanic zone north of taipei metropolitan area of taiwan area of five million people we used the data collected from a seismic network deployed for 5 years over the volcanic zone this plus another data from taiwan regional networks allow us to carry out tomographic inversions for v p v p v s and q p structures beneath the tatun volcanic zone based on our results and other geological tectonic and seismic findings we reconstruct the structural evolution of the crust in the tatun volcanic zone and discuss the implication to the surrounding faults fractured zones and discuss potential future volcanic activities from the tomographic results there appear to exist a tube shaped highly fractured ancient magma passage with high seismic velocities that parallel to the chinshan fault and magma passage extends to the southeast at the depth about 20 km this structure suggests plutonic intrusion passage beneath the tatun volcano group that may have been associated with the earlier subduction of the philippine sea plate melting of the subducted plate at depth has generated the magma intrusion that has brought about the tatun volcanic activities the high seismicity today also implies a highly fractured crust due to the hydrothermal activities and induced crustal stress the hydrothermal fluid rich upper crust as indicated by the low v p v s ratio may have important bearing on the potential hazards associated with the two active faults cutting through both the taipei basin as well as the tatun volcanic groups

pangea extravagant sedimentary resource formation during supercontinent configuration an overview abstract the pangea supercontinent stage the interval from the late carboniferous to earliest jurassic is known for its rich and diverse economic resources from sedimentary systems their uniqueness is not the abundance but the resource association on a global scale and even more the time space distributions the evolution of the supercontinent configuration in context of icehouse to coldhouse stages generated maximum coal evaporite and phosphate deposition furthermore important hydrocarbon uranium and sedimentary metal deposits sedimentary fe and al deposits are very rare also typical is the absence of resources from organic deposition during the early triassic the extravagant spatial distribution of these resource systems but also the timing of their occurrences is linked to the tectonic evolution of pangea during accretion zenith amalgamation and breakup as well as to the resulting paleogeographic climatic oceanographic and ecological reorganization of the biosphere the published data on pangean resources are reviewed and reveal a conspicuous pangean pattern these time space relationships are explained in the context of paleotectonic and ecological changes during the supercontinent stage

compositions and flux of soil gas in liu huang ku hydrothermal area northern taiwan abstract soil co 2 flux has been considered a useful proxy to remotely monitor volcanic activity in a hydrothermal area within a safe distance the liu huang ku lhk area which is close to the taipei basin and many existing active fumaroles and hot springs was chosen for the first systematic soil gas study in a hydrothermal area of taiwan in 2004 and 2006 the soil co 2 flux was measured by the closed chamber method with a non dispersive infrared detector soil co 2 emission rate was estimated 19 8 0 2 t day 1 and 582 t km 2 day 1 in 2004 and 22 4 0 2 t day 1 and 659 t km 2 day 1 in 2006 respectively these values are close to those reported for other active high co 2 flux hydrothermal areas of the world it implies that magmatic gases are actively degassing from subsurface in northern taiwan helium and carbon isotopic data reveal that soil gas in lhk is mainly derived from the mantle and is mixed with a small amount of crustal and air components the abundance of soil co 2 shows a positive correlation with the 3 he 4 he ratios and total sulfur contents which are considered as magmatic sensitive indicators for the fumarolic samples therefore soil co 2 could be used as a good proxy for future monitoring of magmatic activity in this area

soil co2 flux in hydrothermal areas of the tatun volcano group northern taiwan abstract we measured soil co2 flux in the representative hydrothermal areas of the tatun volcano group tvg to better understand the volcano s dynamic nature and to estimate its soil co2 degassing output results show that the average soil co2 fluxes obtained at da you keng dyk geng tze ping gtp she haung ping shp and tatun natural park tnp were 128 g m 2 d 1 518 g m 2 d 1 420 g m 2 d 1 and 25 g m 2 d 1 respectively the range is comparable to other active volcanic hydrothermal areas in the world along with liu huang ku lhk where the soil co2 flux is known the total soil co2 output from measured areas is evaluated at 82 t d 1 furthermore a first total soil co2 output from the whole hydrothermal areas of the tvg is roughly estimated at 113 t d 1 which includes 15 t d 1 mantle contribution considering the mantle derived co2 flux and h2o co2 ratio of fumarolic gas thermal energy associated with the diffuse degassing at the tvg hydrothermal area is estimated at 8 2 mw carbon 13c and helium 3he 4he isotopic ratios of soil samples of the studied areas ranged from 4 4 to 6 7 and 2 45 to 6 98 ra respectively the extent of air involvement in the soil degassing system as constrained by the helium and carbon isotopic compositions provides essential information for depicting regional degassing features of the hydrothermal areas

seawater rare earth element patterns preserved in apatite of pennsylvanian conodonts past workers have used rare earth element patterns recorded in biogenic apatite as proxies for original seawater chemistry to explore the potency of this approach we analyzed pennsylvanian conodonts from limestones gray shales and black shales of the fort scott and pawnee formations desmoinesian and swope and dennis formations missourian in kansas missouri and iowa u s a analysis of individual platform conodonts from seven taxa using laser ablation inductively coupled plasma mass spectrometry la icp ms revealed a consistent enrichment in the middle rare earth elements mree analogous mree enrichment has been observed in authigenic apatite and bulk samples of phosphate rich black shales from the same formations importantly however phosphate depleted shales intimately associated with the p rich intervals are relatively depleted in mree these antithetic patterns argue convincingly for secondary migration from the bulk sediment into the phosphate and the extent of mree enrichment in the conodonts is correlated positively with the total ree content mree enrichment in conodonts does not vary systematically as a function of lithology stratigraphic level conodont genus geographic location or with independent estimates of paleoredox conditions in the bottom waters collectively these results argue for postmortem diagenetic ree uptake resulting in a pronounced and progressive mree enrichment any cerium anomalies if initially present were masked by diagenetic uptake of ree paleoenvironmental interpretations of conodont ree particularly for samples exhibiting mree enrichment should therefore be viewed with caution

overview of the stability and barrier functions of the granitic geosphere at the kamaishi mine relevance to radioactive waste disposal in japan abstract the kamaishi in situ studies were carried out in order to provide a technical basis for the studies of the geological disposal of high level radioactive waste hlw in japan the studies were conducted in drifts located at ca 300 m and ca 700 m below the surface in the former kamaishi iron ore mine situated in the kurihashi granodiorite an early cretaceous granitic rock 110 120 ma in the kitakami area iwate prefecture northeastern japan the fractures identified in the kurihashi granodiorite were mainly formed during the early stages of the cooling process the mineralogical and dating data suggest that almost no new fractures have been generated since 70 60 ma ago the fractures have high porosity fracture fillings with relatively high sorption values that imply the fractured granitic rock could have a significant retardation capability for contaminant transport through the granite monitoring of hydrological and geochemical conditions of groundwater for 10 years showed that even fractured granitic rock close to the drift is not thoroughly oxidized and there are only negligible changes of hydrological conditions and groundwater geochemistry due to earthquakes this information is of considerable importance for the practical design of a hlw repository and to assess any impact of the pre closure conditions on the post closure performance of the geological repository finally the results of the study methodology and tools developed help increase confidence in the technical feasibility of geological disposal of hlw in japan

effects of realistic surface topography on seismic ground motion in the yangminshan region of taiwan based upon the spectral element method and lidar dtm we combine light detection and ranging lidar digital terrain model dtm data and an improved mesh implementation to investigate the effects of high resolution surface topography on seismic ground motion based upon the spectral element method in general topography increases the amplitude of shaking at mountain tops and ridges whereas valleys usually have reduced ground motion as has been observed in both records from past earthquakes and numerical simulations however the effects of realistic topography on ground motion have not often been clearly characterized in numerical simulations especially the seismic response of the true ground surface here we use lidar dtm data which provide two meter reso lution at the free surface and a spectral element method to simulate three dimensional 3d seismic wave propagation in the yangminshan region in taiwan incorporating the effects of realistic topography a smoothed topographic map is employed beneath the model surface in order to decrease mesh distortions due to steep ground surfaces numerical simulations show that seismic shaking in mountainous areas is strongly affected by topography and source frequency content the amplification of ground motion mainly occurs at the tops of hills and ridges whilst the valleys and flat topped hills experience lower levels of ground shaking interaction between small scale to pographic features and high frequency surface waves can produce unusually strong shaking we demonstrate that topographic variations can change peak ground accel eration pga values by 50 in mountainous areas and the relative change in pga between a valley and a ridge can be as high as a factor of 2 compared to a flat surface response this suggests that high resolution realistic topographic features should be taken into account in seismic hazard analysis especially for densely populated moun tainous areas

paleoshoreline patterns in the transgressive regressive sequences of pennsylvanian rocks in the northern appalachian basin u s a abstract sheets of sponge spicule flint of pennsylvanian age bashkirian moscovian kasimovian that are present in the northern appalachian basin of ohio and adjacent parts of kentucky pennsylvania and west virginia are important indicators of paleoshorelines this flint typically occurs with or occupies the position normally held by shallow water limestone and contains a normal marine fauna the flint was deposited above coal or underclay representing the detritus starved marine portion of a transgressive regressive sequence and marking the eastern limit of transgression across a westward spreading alluvial plain flint occurs at several stratigraphic positions in the upper pottsville lower conemaugh interval the most important are boggs upper mercer and kanawha flints of the upper pottsville group kilgore flint ridge zaleski and vanport flints of the lower allegheny group and brush creek flint of the lower conemaugh group lithofacies maps of these beds were constructed to show the distribution of the flint limestone hosted flint occurs in long discontinuous chains of sheetlike bodies whereas shale hosted flint occurs in single sheets with restricted geographic distribution chains of limestone hosted flint attain maximum dimensions of a few meters in thickness a few kilometers in width and several hundreds of kilometers in length the upper mercer vanport and brush creek flints are particularly extensive forming arcuate shoreline patterns that parallel the fronts of large delta systems beds of clay ironstone and or coal above flint indicate that the lagoonal environment in which flint was deposited was followed closely by a change to stagnant waters cementation of flint with silica likely occurred under the lower ph conditions existing at that time and when depths of burial were shallow

low frequency submarine volcanic swarms at the southwestern end of the okinawa trough 1 a low frequency lf submarine volcanic swarm has been first observed at the southwestern end of the okinawa trough where some submarine volcanoes have recently been identified a swarm of more than 24 earthquakes was recorded at land seismic stations in taiwan between september 1st and september 4th 2006 these earthquakes without clear s arrivals were substantially different from other abundant tectonic earthquakes in the area the dominant frequency of around 1 or 2 hz recorded at all stations shows that the lf seismograms were generated by neither path nor site effects but directly from the source these lf earthquakes can be characterized as b type volcanic earthquakes which have been observed in some active volcanoes before significant eruptions the observations of these lf volcanic earthquakes beneath submarine volcanic cones and seamounts are strong indicator that some submarine volcanoes are still active at the southwestern end of the okinawa trough

pennsylvanian continental cyclothem development no evidence of direct climatic control in the upper freeport formation allegheny group of pennsylvania northern appalachian basin abstract the occurrence of lacustrine carbonates in the allegheny group upper middle pennsylvanian continental cyclothems of the northern appalachian basin has been attributed to climatic alternation of wet coal deposition and dry carbonate deposition periods however we present evidence from facies associations coal and carbonate petrography and carbonate stable isotope geochemistry for a uniformly wet climate throughout deposition of one of the earliest continental cyclothems the upper freeport formation uff we propose a depositional model comprising a large wetland complex drained by an anastomosed fluvial system containing a mosaic of channels freshwater siliciclastic and carbonate lakes and peat bogs swamps on a siliciclastic floodplain carbonate phases represent bio induced precipitates modified by lake dynamics and not evaporative deposits absence of covariant isotopic trends between 18o and 13c and a relatively small range of 18o values 1 9 to 6 4 pdb that are close to or lighter than predicted paleoprecipitation for the pennsylvanian equatorial regions indicate hydrologically open short residence time lake systems in support of our sedimentary model combined sedimentologic and isotopic data do not indicate reduced effective moisture precipitation evaporation during intervals of limestone deposition the uff lakes developed in a relatively wet climate zone without significant episodic closure due to climatically induced water deficit lithologic patterns within the uff cyclothem are primarily attributed to the evolution of anastomosed fluvial systems controlled by subsidence in an active foreland basin rather than to short term climatic change or eustacy

a major hydrothermal reservoir underneath the tatun volcano group of taiwan clues from a dense linear geophone array a dense linear geophone array is deployed across the tatun volcano group tvg at the northern tip of taiwan where more than 7 million residents live in the taipei metropolis the array is composed of 50 geophones with a station spacing of 200 m in average and it is designed for striking in the nw se direction to record the many earthquakes in eastern taiwan where the philippine sea plate subducted beneath the eurasia plate the detailed examination of felt earthquakes shows consistent p wave delays are recorded at particular stations of the array the further forward modeling indicates there is a low velocity zone lvz at depths between 0 5 and 2 5 km beneath the major fumarole sites combining this preliminary result with previous studies including clustering seismicity volcanic earthquakes low resistivity zone strong degassing processes and shallow velocity structures we suggest that the lvz might be associated with the major hydrothermal reservoir at the tvg the identification of the hydrothermal reservoir by the lvz not only implies a potential volcanic threat such as phreatic eruptions in the future but also provides the possibility of sustainable geothermal resources for replacing traditional nuclear and fossil fuel power plants detailed images of the lvz and other volcanic structures will be obtained soon when dense geophone arrays with more than 600 geophones are deployed from 2020 to 2022

the 1989 earthquake swarm beneath mammoth mountain california an initial look at the 4 may through 30 september activity abstract mammoth mountain is a 50 000 to 200 000 year old cumulovolcano standing on the southwestern rim of long valley in eastern california on 4 may 1989 two m 1 earthquakes beneath the south flank of the mountain marked the onset of a swarm that has continued for more than 6 months in addition to its longevity noteworthy aspects of this persistent swarm include 1 an exponential like increase in the rate of activity through the first month 2 a vertically oriented planar distribution of hypocenters at depths between 6 and 9 km with a north northeast strike roughly perpendicular to the average t axis orientation for the swarm earthquakes 3 recurring spasmodic bursts rapid fire sequences of similar sized earthquakes with overlapping coda and occasional earthquakes with enhanced low frequency energy 4 a uniform temporal distribution of the four largest m 3 events over the first 4 months of the swarm with a cumulative seismic moment for the entire sequence through 30 september corresponding to a single m 4 earthquake 5 a b value of 1 2 and 6 submicrostrain perturbations on the nearby borehole dilatometer the first of which led the onset of swarm activity by more than 2 weeks these aspects of the swarm together with its location along the southern extension of the youthful mono inyo volcanic chain which last erupted 500 to 600 years ago point to a magmatic source for the modest but persistent influx of strain energy into the crust beneath mammoth mountain

chalcedonic quartz and occurrence of quartzine length slow chalcedony in pelagic sediments abstract chalcedony is the most abundant form of quartz in silicified pelagic sediments from the north pacific varieties of chalcedonic quartz present in chert of deep sea origin include chalcedony length fast and zebraic quartzine length slow and lutecite these occurrences of quartzine in known pelagic sediments emphasize the dangers of using quartzine as an indicator of former evaporitic environments quartzine is a diagenetic mineral and does indicate pore fluids rich in sulphate and magnesium in pelagic sediments it is always associated with authigenic barite and in many cases with authigenic dolomite quartzine should not be used by itself as an indicator of any particular environment of deposition

sedimentologic and stratigraphic constraints on the orientation of the late triassic northern indian passive continental margin abstract the orientation and distribution of the northern indian passive continental margin basin during different epochs constrained the geometric characteristics of the hyperextended northern indian edge greater india traditional paleogeographic reconstructions envisage the late triassic northern indian passive continental margin as e w trending whereas paleomagnetic data support an 55 counterclockwise rotation during northward drifting this case study of upper triassic units from the northern indian margin based on facies analysis sandstone petrography heavy mineral assemblages u pb detrital zircon geochronology and stratigraphic correlation from the zanskar range to southern tibet provides new constraints and suggests that the northern indian passive continental margin might have been n s trending in the late triassic given the dominance of quartz sandstones with zircon tourmaline and rutile indicating a provenance from continental blocks and the recycling of older quartz rich sandstones and detrital zircon age spectra characterized by a neoproterozoic detrital zircon u pb age peak 921 13 ma the upper triassic sandstones widespread along the tethyan himalayas may have been partly derived from the eastern ghats mobile belt in eastern india and the rayner orogen in eastern antarctica the upper triassic quartzite series comprises feldspatho quartzose to pure quartzose sandstones with intercalated bioclastic oosparites deposited in backshore foreshore and shoreface coastal environments without considering the subsequent counterclockwise rotation of india the consistent pattern of the upper triassic bidirectional e w paleocurrent observed throughout the himalaya suggests that the paleoshoreline was striking near n s approximately perpendicular to the regional orientation of the northern indian margin progressive eastward thickening of the sandstone layers and eastward younging of the quartzite series suggest diachronous sedimentation such stratal patterns and the strike of the late triassic paleoshoreline were attributed to the neo tethys transgression from the zanskar range to southern tibet

pennsylvanian cyclothems methods of distinguishing tectonically induced changes in sea level from climatically induced changes analysis of tectonic subsidence permits calculation of the magnitude of tectonic processes and associated climatic effects which controlled changes in sea level during deposition of pennsylvanian cyclothems far field tectonic effects in response to regional orogenic movements influenced pennsylvanian sea level change in the midcontinent of north america and the illinois basin organization of virgilian and missourian midcontinent cyclothems into fourfold to fivefold bundles shows that sea level changes in midcontinent platform areas were influenced partly by milankovitch orbital parameters whereas desmoinesian sea level change apparently was influenced more strongly by tectonic subsidence sea level change associated with cyclothems in the central appalachian basin and the asturias basin of spain were controlled mostly by foreland basin subsidence and later strike slip faulting methods developed herein permit calculation of magnitudes of both tectonic and glacio eustatic components of sea level change influencing pennsylvanian cyclothem deposition and may be applicable to other cyclic sequences

spatial and temporal distribution of microbial carbonates skeletal and non skeletal grains in a pennsylvanian carbonate platform valdorria northern spain abstract the valdorria carbonate platform in northern spain features a well preserved and continuous outcrop of a bashkirian platform to basin transect during the asatauian late bashkirian the platform growth changed gradually from a progradational to an aggradational mode recording 10 most likely short eccentricity controlled cyclothems the facies of the platform top and slope have been mapped and the architecture of each cyclothem schematically reconstructed the distribution of microbial carbonates microbially mediated precipitates skeletal grazers burrowers corals filter feeders algae foraminifera osagia like oncoids and thartarella terebella worm tubes and non skeletal grains faecal pellets has been quantified for the transgressive regressive periods of deposition transgressive maximum flooding early and late regressive intervals of each cyclothem this study shows that the distribution of microbial carbonates skeletal and non skeletal grains along a carbonate platform transect is variable through time and mainly governed by a set of measurable interconnected factors regulating the local palaeoenvironments the water depth and the wave energy facies along the platform profile inner outer break slope during periods of sea level fluctuations transgressive to regressive intervals of deposition auloporid corals siliceous sponges phylloid algae and osagia like oncoids are characteristic of a low energy environment situated from estimated palaeo water depths of 25 to 80 metres below sea level mbsl onward that formed in the outer platform during the maximum flooding intervals anthracoporella archaeolithoporella boundstone is characteristic of the moderate energy environments created in the horizontal inner platform during the transgressive intervals microbially mediated precipitates are reliable indicators of the slope and masloviporidium indicator of low energy environments of the upper slope on the platform top ungdarella and donezella are more abundant during the early regressive intervals than during any other interval stacheoids are mainly present in the water depth range of 10 to 60 mbsl tournayellids from 15 to 35 mbsl and archaediscids from 15 to 75 mbsl all in low to moderate energy conditions rugose corals are common in the water depth range of 5 to 35 mbsl either during the transition from the early to the late regressive intervals as solitary forms or forming boundstone or during periods of higher sea level stand as solitary forms in floatstone fenestellids fistuliporids and trilobites occur mainly in the slope but are also common in the platform top during the maximum flooding and or the early regressive intervals archaeolithoporella is a reliable indicator of the platform top deposits but its abundance is closely linked to the presence of adequate substrates a high abundance in the assemblage of gastropods endothyrids palaeotextulariids bradyinids and fusulinids characterizes the platform top shallow water coated grain grainstones formed under high energy currents during the late regressive intervals tetrataxids act as encrusters on microbial precipitates of the slope or on phylloid algae and archaeolithoporella of the platform top but are also observed as nuclei of coated grains brachiopods are more abundant in low to moderate energy and 35 to 55 mbsl environments that prevailed during the transgressive intervals faecal pellets were commonly observed in low energy environments from 50 to 325 mbsl at the platform break and in the slope and the same applies for thartarella terebella worm tubes that are virtually absent in high energy deposits finally crinoids lasiodiscids and tuberitinids are randomly distributed and are not indicative of any specific environment the here well constrained distribution patterns of microbial carbonates skeletal and non skeletal grains in valdorria outcrop hold the potential to serve as a reference for interpretation of depositional environments of other platforms using biota associations and depositional texture particularly in regions where the platform geometry is not preserved or is not fully exposed

hydrothermal mn deposits of the franciscan assemblage ii isotope and trace element geochemistry and implications for hydrothermal convection at spreading centers abstract major element trace element and sr nd pb and o isotopic data for a franciscan mn deposit suggest an origin by seafloor hydrothermal circulation based on q mode factor analysis the cherts and mn lenses of the blue jay mine formed from a combination of 4 components representing 1 biogenic 1 hydrothermal and 2 detrital sources rb sr u th pb and o isotopic systematics in the mn lenses were affected by input from the hydrothermal circulation of material leached from the underlying basalts nd isotopic compositions in both cherts and mn lenses are identical and within the range measured for pacific ocean water suggesting the ree were not mobilized by hydrothermal activity correlation of 18 o with sio 2 and mno 2 in the mn lenses implies the lenses formed by simple mixing of hydrothermally derived mn oxides with seawater and biogenic silica 18 o of the cherts is both uniform and depleted relative to dsdp jurassic cherts but similar to microquartz bearing cherts of the monterey formation this suggests that diagenetic activity exerted more control on oxygen isotope compositions then hydrothermal alteration or metamorphism finally a well defined rb sr isochron of 158 5myr was obtained for these cherts and opens the possibility of determining absolute radiometric ages for similar cherts throughout the geologic record

stratigraphic architecture of lower permian cyclic carbonate reservoirs chase group in the mid continent usa based on outcrop studies seven depositional sequences each of which consists of two intermediate order cyclothems compose outcrops of the chase group permian wolfcampian in the mid continent principal reservoir analog facies are restricted mainly to the highstand systems tracts of cyclothems these facies include subtidal lime sands deposited mainly in downdip distal ramp settings and peritidal dolomudstones deposited farther updip on the ramp the stratigraphic and depositional architecture of the section was controlled by the interplay among paleobathymetry glacio eustasy and periodic syndepositional tectonism porous lime sands dominate in the lower part of the chase group the forced regressive unconformity bounded sequences within which they occur were deposited during relatively high magnitude eustatic fluctuations that resulted in marine accommodation increases great enough to preclude peritidal deposition porous peritidal facies instead dominate in the upper part of the chase group the sequences within which these normal regressive deposits are present were deposited during lower magnitude eustatic fluctuations and decreased marine accommodation which allowed for their eventual progradation across the ramp complex porosity heterogeneity is evident within individual depositional sequences and component cyclothems as well as vertically within the chase group

the influence of terrestrial run off on marine biotic communities an example from a thrust top carbonate ramp upper pennsylvanian foreland basin picos de europa nw spain article i nfo high diversity marine biotic communities characterize the lower kasimovian upper pennsylvanian carbonates of the las llacerias formation in the andara massif picos de europa province cantabrian mountains spain the carbonates accumulated on a small thrust top ramp system within the shallow low energy and euphotic realms biotic communities were characterized by abundant photozoans calcareous algae and cyanobacteria and heterozoans including filter and suspension feeders calcareous and siliceous sponges bryozoans brachiopods crinoids diverse other metazoans rugose solitary and colonial corals tabulate corals bivalves gastropods and echinoids benthic foraminifers including very abundant small incrusting tubiforms and conspicuous swarms of cement filled spheres calcispheres or penella small sized buildups of chaetetid sponges syringoporids branching rugose corals anthracoporella and phylloid algae commonly developed in these shallow water environments meanwhile mud mounds formed at greater water depths mostly below the lower limit of the phothic zone the occurrence of such diverse biotic communities and the grain composition of the shallow water deposits not recorded in the platform top successions of the antecedent bashkirian moscovian carbonate shelf valdeteja and picos de europa formations are interpreted as linked to increased nutrient levels mesotrophic to mildly eutrophic conditions in the actual sea surface water the nutrients are inferred to have resulted from land derived fluxes from the rivers draining the adjacent growing variscan orogenic chain nutrients were subsequently transported into the narrowed marine shallowing foreland basin located in the eastern side of pangea within the palaeoequatorial humid belt comparison to the pennsylvanian auernig group in the carnic alps allows the discrimination between the influence of land derived versus upwelling derived nutrients providing a useful tool in the interpretation of biotic assemblages in the fossil rock record

the upper mississippian bluefield formation in the central appalachian basin a hierarchical sequence stratigraphic record of a greenhouse to icehouse transition abstract the upper mississippian chesterian bluefield formation is the basal unit of the predominantly siliciclastic mauch chunk group in the appalachian basin this formation developed in a northeast southwest oriented foreland trough fronting the alleghanian highlands to the southeast regional cross sections and isopach maps of the bluefield formation in southeastern west virginia southwestern virginia and southeastern kentucky define a depocenter in the southeastern part of the study area and a paleovalley system along the basin margin to the northwest at most localities facies that make up the bluefield formation are stacked into 1 15 m thick upward shallowing parasequences each of which is capped by a flooding surface these parasequences are stacked into four regionally correlatable depositional sequences on the margins of the depocenter incised valleys and fewer meter scale parasequences characterize the depositional sequences stacking of parasequences into sequences reflects a hierarchy of greenhouse type fifth order and icehouse type fourth order sea level cycles superimposed on a differential subsidence history related to early alleghanian thrust loading the bluefield depocenter experienced greater total accommodation which prevented incision during lowstands instead lowstands are typified by preservation of fifth order coal bearing parasequences in the depocenter basin margin areas experienced less total accommodation which resulted in development of fourth order lowstand valleys and erosion of parasequences this study demonstrates that both tectonic and eustatic forcing mechanisms controlled stratigraphic evolution of the bluefield formation

trace metal records of regional paleoenvironmental variability in pennsylvanian upper carboniferous black shales abstract regional geochemical differences within a laterally continuous cyclic pennsylvanian upper carboniferous shale in midcontinent north america are interpreted in light of models of glacioeustatic forcing and new views on water column paleoredox stability and trace metal behavior in black shale environments specifically we characterize differences in transition metal fe mn mo v ni zn pb and u concentrations in black shales of the hushpuckney shale member of the swope limestone in iowa and equivalent black shale beds of the coffeyville formation in oklahoma although c s fe systematics and uniform 34 s depleted isotope ratios of pyrite indicate pervasive euxinic deposition anoxic and sulfidic bottom waters for these shales regional variations can be inferred for the efficiency of mo scavenging and for the rates of siliciclastic sedimentation as expressed in spatially varying fe al ratios black shales in iowa show mo enrichment roughly five times greater than that observed in coeval euxinic shales in oklahoma by contrast fe al ratios in oklahoma shales are as much as five times greater than the continental ratio of 0 5 observed in the over and underlying oxic facies and in the coeval black shales in iowa recent work in modern marine settings has shown that enrichments in fe commonly result from scavenging in a euxinic water column during syngenetic pyrite formation in contrast to fe the concentrations of other transition metals mo v ni pb zn u are typically more enriched in the black shales in iowa relative to oklahoma the transition metal trends in these paleozoic shales are reasonably interpreted in terms of early fixation in organic rich sediments due to euxinic water column conditions however regional variations in 1 rates of siliciclastic input 2 organic reservoirs including relative inputs of terrestrial versus marine organic matter and 3 additional inputs of metals to bottom waters from contemporaneous hydrothermal vents are additional key controls that lead to geographic variation in the extent of metal enrichments preserved in ancient organic rich sediments

shallow crustal velocities and volcanism suggested from ambient noise studies using a dense broadband seismic network in the tatun volcano group of taiwan abstract the tatun volcano group tvg is situated adjacent to the taipei metropolis and was active predominantly around 0 8 0 2 ma pleistocene various recent lines of evidence suggest that the tvg is a potentially active volcano and that future volcanic eruptions cannot be ruled out geothermal activities are largely constrained to faults but the relationship between volcanism and detailed velocity structures is not well understood we analyzed ambient seismic noise of daily vertical components from 2014 using a dense seismic network of 40 broadband stations we selected a 0 02 grid spacing to construct 2d and 3d shallow crustal phase velocity maps in the 0 5 3 s period band two s wave velocity profiles transect chishingshan mt cs in the shallow 3 km crust are further derived the footwall of the shanchiao fault is dominated by low velocity which may relate to tertiary bedrock buried under andesitic lava flows dozens to hundreds of meters thick the hanging wall of the shanchiao fault is the location of recent major volcanic activities low velocity zones in the southeast of dayoukeng dyk may be interpreted as hydrothermal reservoirs or water saturated tertiary bedrock related to cenozoic structures in the shallow crust high velocities conspicuously dominate the east of the tvg where the earliest stages of volcanism in the tvg are located but where surface hydro geothermal activities were absent in recent times between the shanchiao fault and kanchiao fault high velocities were detected which converge below mt cs and may be related to early stages of magma conduits that gradually consolidated these two faults may play a significant role with the tvg the submarine volcanism adjacent to the keelung coastline also requires further attention

time space variation of volcano seismic events at la fossa vulcano aeolian islands italy new insights into seismic sources in a hydrothermal system we investigated the relationship between volcano seismic events recorded at la fossa crater of vulcano aeolian islands italy during 2004 2006 and the dynamics of the hydrothermal system during the period of study three episodes of increasing numbers of volcano seismic events took place at the same time as geothermal and geochemical anomalies were observed these geothermal and geochemical anomalies have been interpreted as resulting from an increasing deep magmatic component of the hydrothermal fluids three classes of seismic events long period high frequency and monochromatic events characterised by different spectral content and various similarity of the waveforms have been recognised these events clustered mainly below la fossa crater area at depths of 0 5 1 1 km b s l were space distributed according to the classes based on their features we can infer that such events at vulcano are related to two different source mechanisms 1 fracturing processes of rocks and 2 resonance of cracks or conduits filled with hydrothermal fluid in the light of these source mechanisms the increase in the number of events at the same time as geochemical and geothermal anomalies were observed was interpreted as the result of an increasing magmatic component of the hydrothermal fluids implying an increase of their flux indeed such variation caused an increase of both the pore pressure within the rocks of the volcanic system and the amount of ascending fluids increased pore pressures gave rise to fracturing processes while the increased fluid flux favoured resonance and vibration processes in cracks and conduits finally a gradual temporal variation of the waveform of the hybrid events one of the subclasses of long period events was observed likely caused by heating and drying of the hydrothermal system

tornillo type seismic signals at galeras volcano colombia 1992 1993 abstract unusual low frequency seismic events called tornillos screws at the observatorio vulcanologico y sismologico de pasto ovsp have been observed at galeras volcano during 1992 1993 of six eruptions that occurred between july 1992 and june 1993 five were preceded by episodes of tornillo signals these signals are characterized by 1 a waveform having a homogeneous distribution of frequencies 2 a long coda lasting up to several minutes 3 a small amplitude compared to the duration and 4 a slow decay of the coda the tornillo signals have been grouped into thirteen principal forms the 1992 1993 tornillos showed four main periods of occurrence each of which was followed by an eruption episode i occurred from 11 to 16 july 1992 and consisted of nine events episode ii lasted from 23 december 1992 to 14 january 1993 with twenty events episode iii was observed from 13 february to 23 march 1993 with 74 events episode iv lasted from 10 april to 7 june 1993 with 109 events the seismic activity at galeras in april may 1993 was characterized mainly by the occurrence of tornillo signals the behavior of these signals was similar to that before previous episodes ending with eruptions these observations permitted us to forecast the 7 june 1993 eruption several days to weeks beforehand the occurrence of tornillos is the most important criterion for determining the probability of an eruption at galeras in the current period of reactivation the maximum daily number of tornillos and the longest duration of individual events occur near the end of each episode within an individual episode the durations of single events increase progressively near to the point of eruption a positive correlation is observed between the total number of pre eruptive tornillo signals during an episode and the volume of material ejected by the eruption these observations may suggest that the presence of tornillos is an indication of variations in the physical conditions between the fluid and the surrounding solid material within the volcano and they constitute an important tool for forecasting future eruptions at galeras

coal more than a resource critical data for understanding a variety of earth science concepts abstract coal is one of the world s primary energy sources and it is critical for making coke used in steel making and is used for a multitude of chemical products aside from its significance as a fuel or product however coal and data derived from the exploration or mining of coal have also provided the foundation and testing ground for diverse geologic concepts because of coal s economic importance and common variability in thickness distribution and quality it has been critical to collect and correlate a wide variety of surface and subsurface data sets at relatively high spatial frequency which varies from the mine to basinal scale also because many coal beds occur in most coal basins the collection of coal data from multiple beds creates relatively high temporal frequency data sets at scales from laminae to bed to larger unit scale these data have been important for the development and expansion of many earth science concepts including aspects of basin analyses paleogeography paleoclimatology paleontology stratigraphy sedimentology structural geology and tectonics

non sorbing tracer migration experiments in fractured rock at the kamaishi mine northeast japan this paper describes the design implementation and analysis of in situ tracer migration experiments in fractured granite the research highlights the importance of geo hydraulic investigations prior to performing tracer migration experiments the authors conducted a detailed but simple investigation in order to understand the spatial distribution of conductive fractures and the pressure field seven boreholes were drilled in the test area revealing hydraulic compartmentalization and a heterogeneous distribution of conductive features after identifying several suitable conductive fractures three sets of dipole tracer migration experiments were conducted with various combinations of injection and withdrawal hole and dipole ratios the tracer breakthrough curves were analyzed using a streamline analytical solution and numerical analysis of mass transport best fit calculations of the experimental breakthrough curves were obtained by assigning apertures within the range of one to ten times the square root of transmissivity and a dispersion coefficient equal to one tenth of the migration length

parameterization of multichromatic tornillo signals observed at galeras volcano colombia in the past decade several of the ash eruptions at galeras volcano colombia have been preceded by tornillos these unusual tremor wavelets have quasi sinusoidal waveforms with screw like envelope profiles and can last up to several minutes a swarm of tornillos occurred at galeras volcano between 8 december 1999 and 12 february 2000 these tornillos appear to be more complex than those previously recorded with the broadband instruments or with the short period network of the observatorio vulcanologico y sismologico in pasto they are multichromatic with a varying number of narrow spectral peaks between 1 and 20 hz we describe a procedure for parameterizing the tornillo signals in the time and frequency domains to determine signal parameters in addition to wavelets like the tornillos the procedure can be applied to random signals such as volcanic tremor we derive distribution and correlation functions for the signal parameters determined from the swarm these provide along with the signal signature constraints for modelling variations of the source process from these observations we derive qualitative conclusions about the characteristics of differential equations which describe the underlying processes and excitation mechanisms as forced or self excited oscillators

diagenetic trends in the siliceous facies of the monterey shale in the santa maria region california x ray diffraction and oxygen isotopic analyses of outcrop and subsurface samples of siliceous rocks were used to reconstruct thermal and diagenetic histories of the miocene monterey shale near santa maria california within many stratigraphic sections soft porous diatomaceous rocks change gradationally to underlying hard and brittle chert porcellanite and siliceous shale the accompanying silica mineral zones are in descending stratigraphic order 1 biogenic silica opal a 2 cristobalitic silica opal ct and 3 microcrystalline quartz boundaries between silica mineral zones and stratigraphic horizons are often discordant within the opal ct zone the d 101 spacing of opal ct decreases in a smooth non linear fashion from about 4 10 a to 4 04 a in the santa maria valley and bradley oil field areas the thicknesses of the opal ct zones are greater and the present thermal gradients less than in the adjacent orcutt oil field thin opal ct zones at shallow maximum burial depths apparently correlate with higher thermal gradients using present thermal gradients and reconstructed maximum burial depths from well data in the santa maria region the ranges in temperatures for the top and base of the opal ct zone are 38 54 c and 55 110 c respectively the temperature difference between these two boundaries ranges from 17 to 60 c in comparison temperature ranges for these two boundaries computed from oxygen isotopic compositions of opal ct and quartz extrapolated experimental quartz water fractionations and assuming o18 0 o for the isotopic composition of the equilibrating fluid are 18 56 c and 31 80 c for the top and base of the opal ct zone respectively the temperature difference between these boundaries is 11 36 c using this method thermal gradients and sedimentation rates strongly influence rates of silica transformations reconstructed thermal and diagenetic histories of siliceous rocks of the monterey shale at four well sites in the santa maria region demonstrate that most silica conversions probably occurred during the last 3 4 myr in response to accelerated rates of sedimentation and therefore burial heating during the pliocene

facies and allostratigraphy of high latitude glacially influenced marine strata of the early permian southern sydney basin australia the sydney basin of new south wales australia is a foreland basin containing a thick up to 10 km permo triassic succession the southern margin of the basin exposes strata deposited during late palaeozoic glaciation of south eastern gondwana the early permian wasp head pebbley beach snapper point formations and wandrawandian siltstone were deposited between 277 and 258 ma on a polar glacially influenced continental margin adjacent to ice sheets located over east antarctica and eastern australia sedimentary facies together with related ichnofacies and fauna can be grouped into six facies associations that record marine sub environments ranging from high energy storm dominated inner shelf to turbidite dominated upper slope settings cold marine conditions with near freezing bottom water temperatures are recorded by glendonites ice rafted debris most likely deposited by icebergs occurs in almost all facies associations an allostratigraphic approach emphasizing the recognition of bounding discontinuities i e erosion surfaces and marine flooding surfaces is used to subdivide the early permian stratigraphy into facies successions three types of succession can be identified and record changes in the relative influence of allocyclic controls such as basin tectonics sediment supply and glacio eustatic sea level variation together sedimentological and allostratigraphic data allow reconstruction of the depositional history of the south western margin of the sydney basin initial marine sedimentation characterized by sediment gravity flows and storm deposited sandstones of the lower wasp head formation occurred adjacent to a faulted basin margin overlying successions within the upper wasp head pebbley beach and snapper point formations record aggradation in inner to outer shelf settings along a storm and glacially influenced continental margin tectonic subsidence and basin flooding is recorded by deeper water turbidites of the wandrawandian siltstone

elucidating the geometry of the active shanchiao fault in the taipei metropolis northern taiwan and the reactivation relationship with preexisting orogen structures the shanchiao fault is an active normal fault with documented paleoearthquakes in the taipei metropolis taiwan while posing direct seismic threat on the multimillion population its crustal scale fault plane configuration has not been constrained this study presents the first attempt to resolve the fault plane dip changes of the shanchiao fault within the upper crust by forward modeling late quaternary deformation tectonic subsidence over the last 23 ka is estimated from vertical displacements of a rapidly formed alluvial fan horizon deformed into a dramatic rollover monocline a 2 d profile across the shanchiao fault is chosen for elastic half space dislocation modeling and the results suggest that the fault is listric in the shallow crust with an abrupt change from subvertical ramp 85 75 to near horizontal flat 10 15 at 3 4 km depth consistent with an origin from the inversion of an orogen related thrust detachment given the presence of rift related fabrics in the underthrust chinese continental margin basement beneath the taiwanese orogenic wedge listric ramp flat ramp models with a second deeper bend to 60 dip are also tested reasonable fits with the geological observations are produced when the lower ramp is located at greater than 8 km depth which correlates with the hypocentral location of a moderate earthquake in 2004 joint reactivation of preexisting thrust and rift faults by the shanchiao fault is therefore plausible with implications for seismic hazard in the taipei area

high frequency earthquakes at white island volcano new zealand insights into the shallow structure of a volcano hydrothermal system abstract volcano tectonic earthquakes at white island are concentrated in a single seismically active zone southeast of the active vents and at depths of less than 1 km a few deeper earthquakes also occur beneath the active vents a composite focal mechanism indicates that the stress regime in the shallow seismic zone is n s extensional shallow seismicity occurs within the main volume of the volcano hydrothermal system that underlies the main crater floor and we interpret this as a region where the rocks have been weakened by past magmatic intrusions elevated pore fluid pressure and physico chemical effects of acid volcanic fluids thereby allowing preferential seismic failure brittle seismic failure within this region requires a temperature less than about 400 c and implies high horizontal temperature gradients close to the active craters and fumaroles spasmodic bursts events are also a result of brittle failure but occur close to zones of significant permeability in response to changes in local fluid pressure

application of sequence and genetic stratigraphic concepts to carboniferous coal bearing strata an example from the black warrior basin usa carboniferous strata provide an excellent example on which to test the application of genetic stratigraphic and sequence stratigraphic concepts both approaches are employed in the evaluation of the coal bearing strata of the black warrior basin south eastern usa bounding hiatal surfaces have been recognized in the succession of rock that includes the mary lee coal zone within the framework of genetic stratigraphy one genetic sequence has been identified comprised of offlap progradational and aggradational facies and onlap aggradational and transgressive facies components seven parasequence sets have been delimited according to the concepts of sequence stratigraphy these have been ascribed to transgressive highstand and shelf margin systems tracts the identification of components of these contrasting frameworks provide the basis for evaluating other carboniferous strata

volcano hydrothermal activity detected by precise levelling surveys at the tatun volcano group in northern taiwan during 2006 2013 abstract precise levelling surveys were conducted from 2006 to 2013 on three levelling routes in the tatun volcano group tvg located approximately 15 km northeast of taipei to detect deformation in relation to the volcano hydrothermal activities of the tvg uplift was detected around the most active fumarole tayoukeng fumarole throughout the period 2007 to 2011 the uplift rate throughout the period from march 2009 to march 2011 was reduced in comparison to the rate between 2007 and 2009 following this a dormant state or a small amount of subsidence was detected in the period march 2011 to march 2013 and throughout the period from june 2006 to march 2013 subsidence was centred on an area 0 5 km east of the summit of mt cising the highest peak in the tvg a model of two spherical sources was therefore estimated from the deformation recorded from august 2007 to march 2011 using a genetic algorithm a deflation source was obtained about 0 5 km northeast of mt cising at a depth of 2 km and an inflation source was situated approximately 1 km south of the tayoukeng fumarole at a depth of 0 7 km based on previous seismic and amt studies the estimated sources are interpreted as being hydrothermal reservoirs because almost all the benchmarks around mt cising show subsidence at a constant speed we conclude that the deeper hydrothermal reservoir at a depth of 2 km may have been releasing hydrothermal fluid at a constant rate throughout the period from 2006 to 2013 however it was suggested that in 2011 the shallower hydrothermal reservoir at a depth of 0 7 km changed from an inflation state to a dormant state or small deflation based on temporal vertical changes around tayoukeng fumarole a possible model for the volcano hydrothermal system is therefore proposed it is considered that the hydrothermal fluid may be supplied intermittently from the magma chamber to the deeper hydrothermal reservoir at a depth of 2 km although this type of fluid input event may not have occurred during our research period and that the hydrothermal fluid upwelling between mt cising and tayoukeng fumarole flows transversally into a highly cracked and fluid saturated area that continues to tayoukeng fumarole the existence of a shallower hydrothermal reservoir at a depth of 0 7 km in the highly cracked and fluid saturated area is therefore plausible

palaeovalleys and protozoan assemblages in a late carboniferous cyclothem sydney basin nova scotia the early stephanian bonar cyclothem of the sydney basin nova scotia contains an erosional surface cut through coastal plain strata with economic coals and distributary channel bodies the erosion surface is interpreted as a palaeovalley 20 m deep and at least 7 km wide that marks a sequence boundary formed during relative fall in sea level the palaeovalley is filled with stacked alluvial channel bodies which become more isolated as the valley fill passes upward into red alluvial plain deposits probably laid down in an anastomosed river system in an adjacent interfluve area calcretes and red vertic palaeosols cap coastal strata assemblage analysis of agglutinated foraminifera and thecamoebians indicates that the palaeovalley was filled with freshwater sediments before an initial marine transgression flooded the alluvial surface and adjacent interfluve valley incision probably reflects glacioeustatic sea level fall however the alluvial nature of the valley deposits suggests that valley filling reflects an abundant sediment supply during lowstand and or transgressive stages and was not a direct consequence of sea level rise during the subsequent transgression phase aggradation was rapid as sediment supply apparently kept pace with rising sea level features of both channel and extra channel facies suggest that seasonality intensified during the transition from coastal plain to palaeovalley and alluvial plain deposition

cyclic sedimentation and climatically caused sea level changes in the late palaeozoic of central europe significant short term fluctuations are characteristic of geological history since precambrian times only the younger quaternary climatic fluctuations are known in more detail as a result of a high grade time resolution climatic change can also be postulated with respect to older cold periods during which polar inland ice sheets developed from a discussion of endogene and exogene interpretations it is shown that global climatic changes and the sea level changes induced by them as well as changes in the position and extent of climatic zones throughout the world provide a control mechanism for sedimentation which is consistent with cyclic sedimentation in late palaeozoic times and also if the basin subsides non cyclically the model allows an explanation of the development of the permo carboniferous sedimentary cycles without numerous short term vertical oscillations of the earth s crust in reality exogene and endogene controls on sedimentation act together in great variety of combinations

secular distribution of biogenic silica through the phanerozoic comparison of silica replaced fossils and bedded cherts at the series level abstract the modern marine silica cycle is dominated by silica secreting phytoplankton principally diatoms but this cycle has evolved considerably during the phanerozoic we analyzed the temporal distribution of silica replaced fossils and bedded chert to determine the influence of factors such as extinctions and climate change on siliceous facies trends in silica replacement of fossils match faunal radiations during the ordovician and siluro devonian with peaks in silica replacement in the late ordovician and middle devonian corresponding to peaks in the abundance and diversity of siliceous sponges sharp drops in the abundance of silica replaced fossils and or bedded cherts coincide with four of the five major mass extinctions no discernible decrease marks the extinction at the end of the triassic we expected peaks in bedded chert deposition during glacial episodes because enhanced ocean circulation should favor more and stronger upwelling orogenic episodes which may trigger continental glaciati

slug tests in fissured aquifers a simple model of a slug test in a fissured aquifer has been studied in order to gain insight into the difficulties of interpreting data from such tests the model is used to estimate the errors that would result from applying the standard type curve analysis to fissured aquifers it is found that the derived aquifer transmissivity will always be overestimated but by a factor which is unlikely to exceed 3 by contrast the derived storage coefficient can be in error by a factor ranging from 10 6 to 105 the volume of the aquifer influenced by a slug test is investigated and a simple formula for estimating the range of a test is suggested

climatically driven cyclicity and peat formation in fluvial setting of the moscovian early kasimovian cracow sandstone series upper silesia poland abstract the approximately 1200 m thick cracow sandstone series middle early late pennsylvanian in the polish part of the upper silesian coal basin consists of 25 70 m thick fining up and laterally widespread fluvial cycles the cycles are marked by alternating sheet like sandstone bodies overlain by much thinner intervals dominated by mudstone and coal these two member cycles record the alternation of a sand dominated fluvial braidplain and floodplain dominated fluvial system with channels confined to narrow belts the lateral persistence internal architecture and isochronous alternations suggest an allogenic origin for the cycles possibly related to climate this interpretation is supported by a three stage evolution of pedogenic processes operating on floodplain deposits beginning with the formation of vertisols followed later by gleying and finally termination by a histosol peat formation such a succession of paleosols indicates a climatic shift from highly seasonal vertisol to humid climate coal with the most seasonal part of the cycle likely represented by the sheet like sandbody the mechanistic link between climate and the cyclic pattern of strata is explained as climatically driven variations in clastic supply which was highest during periods of prominent seasonality short term climatic oscillations generating cyclic patterns in the cracow sandstone series are superimposed on a long term climatic shift towards increased seasonality near the middle late pennsylvanian boundary this is evidenced by the termination of peat formation in the upper silesian basin as well as in some other coeval basins of the equatorial pangea and is interpreted to represent a potentially regional climatic event

a fractal analysis of quaternary cenozoic mesozoic and late pennsylvanian sea level changes sea level changes are related to both climatic variations and tectonic movements the fractal dimensions of several sea level curves were compared to a modern climatic fractal dimension of 1 26 established for annual precipitation records a similar fractal dimension 1 22 based on 18o 16o in deep sea sediments has been suggested to characterize climatic change during the past 2 m y our analysis indicates that sea level changes over the past 150 000 to 250 000 years also exhibit comparable fractal dimensions sea level changes for periods longer than about 30 m y are found to produce fractal dimensions closer to unity and missourian late pennsylvanian sea level changes yield a fractal dimension of 1 41 the fact that these sea level curves all possess fractal dimensions less than 1 5 indicates that sea level changes exhibit nonperiodic long run persistence the different fractal dimensions calculated for the various time periods could be the result of a characteristic overprinting of the sediment record by prevailing processes during deposition for example during the quaternary glacio eustatic sea level changes correlate well with the present climatic signature during the missourian however mechanisms such as plate reorganization may have dominated resulting in a significantly different fractal dimension

glacioeustatic cyclicity of a pennsylvanian carbonate platform in a foreland basin setting an example from the bachende formation of the cantabrian zone nw spain abstract by analysis of outcrop data sequence stratigraphy was used to interpret the stratal architecture and evolution of a moscovian pennsylvanian carbonate platform bachende formation located in the variscan foreland basin of the cantabrian zone nw spain the bachende formation represents a delta top carbonate platform developed in highly subsiding average subsidence rate of 254 m my distal shelf areas of the basin it reached a thickness of 650 m and covered an area of 170 km 2 after conservative palinspastic restorations the platform interior succession is mostly composed of low relief mound shaped micritic boundstones alternating with bioclastic mudstones wackestones peloidal foraminiferal packstones grainstones calcareous algal bafflestones and skeletal and ooidal grainstones landwards to the w carbonate platform beds alternate and interfinger with deltaic sandstones and shallow marine shales the platform interior consists of three sequences s1 s2 and s3 ranging from 180 to 230 m in thickness and from 1 3 to 0 5 my in age these sequences are in turn subdivided into several meter scale 10 6 m average thickness high frequency 110 to 15 ky subtidal transgressive regressive cycles these cycles are bounded by subaerial exposure or marine flooding surfaces and are inferred to be laterally continuous across the platform top they vary from mixed carbonate siliciclastic to carbonate dominated cycles cyclicity on the bachende platform was strongly influenced by glacioeustatic sea level variations and changes in subsidence and sedimentation rates subaerial exposure surfaces capping high frequency cycles are better developed in the sequence 1 late kashirian early podolskian when subsidence was relatively low and glacioeustatic sea level fluctuations could have exposed subtidal deposits during base level falls on the basis of the conservative estimated duration of each cycle and spectral analysis of cycle thickness the precessional 20 ky and obliquity 40 ky cycles were detected in all the sequences the short eccentricity cycle 100 ky in the sequence 1 and the long eccentricity cycle 400 ky in the sequences 2 and 3 podolskian nevertheless precessional and obliquity frequencies seem to dominate during sequences 2 and 3 which were deposited under significant higher subsidence and sedimentation rates additionally spectral peaks at 60 80 ky are randomly present across the whole succession and they cannot be explained as a linear response of the climate system to the milankovitch forcing

seismicity characteristics of a potentially active quaternary volcano the tatun volcano group northern taiwan the tatun volcano group tvg is located at the northern tip of taiwan near the capital taipei and close to two nuclear power plants because of lack of any activity in historical times it has been classified as an extinct volcano even though more recent studies suggestthattvgmighthavebeenactiveduringthelast20ka inmay2003aseismicmonitoringprojectatthetvgareawasinitiated by deploying eight three component seismic stations some of them equipped with both short period and broadband sensors during the 18 months observation period local seismicity mainly consisted of high frequency earthquakes either occurring as isolated events or as a continuous sequence in the form of spasmodic bursts mixed and low frequency events were also present during the same period eventhoughtheyoccurredonlyrarely arrivaltimesfromeventswithclearp s wavephaseswereinvertedinordertoobtaina minimum 1dvelocity modelwithstation corrections probabilistic nonlinear earthquakelocationswere calculated for allthese events using the newly derived velocity model most high frequency seismicity appeared to be concentrated near the areas of hydrothermal activity forming tight clusters at depths shallower than 4 km relative locations calculated using the double difference method and utilising catalogue and cross correlation differential traveltimes showed insignificant differences when compared to the nonlinear probabilistic locations in general seismicity in the tvg area seems to be primarily driven by circulation of hydrothermal fluids as indicated by the occurrence of spasmodic bursts mixed low frequency events and a b value 1 17 0 1 higher than in any other part of taiwan these observations that are similar to those reported in other dormant quaternary volcanoes indicate that a magma chamber may still exist beneath tvg and that a future eruption or period of unrest should not be considered unlikely

probable dynamic triggering of phreatic eruption in the tatun volcano group of taiwan abstract on 16 march 2014 utc a small phreatic eruption occurred in the tatun volcano group tvg of taiwan although it was not reported until analysis of both seismic and acoustic data revealed that the source was in the vicinity of the hsiaoyukeng fumarole a replay of the acoustic data accelerated 60 fold reveals that the gradual decrease in frequency that was recorded produces a volcanic whistle similar to the jet of steam released from a heating kettle the phreatic eruption may have been dynamically triggered by a m6 7 earthquake in chile a similar phenomenon occurred on 5 january 2015 when a phreatic eruption was recorded in the tvg immediately after the generation of dynamic seismic waves by an m5 0 earthquake in japan this is the first scientific report of a phreatic eruption detected in the tvg indicating that these volcanoes are still active as a result it is important to monitor their volcanic activity and identify volcanic reservoirs beneath the tvg to mitigate future possible volcanic impact

gravity monitoring of tatun volcanic group activities and inference for underground fluid circulations abstract the tatun volcano group tvg located on the northern coast of taiwan adjacent to the city of taipei experiences active hydrothermalism but has no historical record of volcanic eruption yet recent studies suggest that tvg is dormant active rather than extinct to monitor mass transfers and to gain further understanding of this volcanic area gravity variations have been recorded continuously since 2012 using a superconducting gravimeter and once every few months since 2005 using absolute gravimeters we analyze the continuous gravity time series and propose a model that best explains the gravity variations due to local groundwater redistribution by correcting these variations we identify gravity changes as large as 35 gal that occurred concomitantly to fluid pressure induced earthquakes and changes in the gas composition at dayoukeng one of tvg s fumaroles over 2005 2007 we examine several fluid movements that can match the gravity observations yet too few additional constraints exist to favor any of them in particular no significant ground displacements are observed when these gravity variations occurred on the other hand the model of gravity changes due to local groundwater redistribution can be routinely computed and removed from the ongoing time gravity measurements in order to quickly identify any unusual mass transfer occurring beneath tvg

carboniferous permian palynostratigraphy of west australian marine rift basins resolving tectonic and eustatic controls during gondwanan glaciations abstract the longest interval of cold climate in earth s phanerozoic history spanned some 55 million years from the namurian late carboniferous to the kungurian early permian when glaciation affected much of high latitude gondwana uncertainty surrounds the timing of glaciation s and the frequency of interglacial episodes ice volumes and the location of ice centres this is because the glacial record is preserved predominantly within marine strata deposited in intracontinental rift basins marginal to onshore ice centres on uplifted basement highs the direct stratigraphic record of glaciation is meagre on adjoining basement highs and extremely difficult to date many basins contain broadly similar threefold lithostratigraphic successions of lowermost glaciomarine diamictite facies middle shales and uppermost carbonate and sandstone rich commonly coal bearing deltaic strata in the absence of absolute age control and infrequent presence of macrofossils such deglaciation sequences are widely assumed to be correlative from basin to basin recording gondwanan deglaciation s and a world wide glacioeustatic sea level rise a newly compiled biostratigraphic database for west australia using first appearance datums of spore pollen types allows correlation of late palaeozoic siliciclastic successions between seven basins bonaparte canning carnarvon collie gunbarrel northern and southern perth basins these extend some 3800 km along australia s western continental margin adjacent to the west australian shield all but the gunbarrel basin contain tripartite glacially influenced successions diamictite shale sandstone biostratigraphic data reveal sharp differences in ages and stratigraphic distributions and marked variations in the thickness of coeval units diamictite shale sandstone successions accumulated diachronously from basin to basin recording a dominant tectonic control on subsidence and relative sea level middle shale units are not exact correlatives between basins and thus are unlikely to simply represent widespread climatically controlled glacioeustatic events instead they are argued to record high relative sea levels during times of maximum synrift subsidence this tectonostratigraphic model can be applied to other intracontinental rift basin successions across gondwana