internal characteristics of ice marginal sediments deduced from georadar profiling and sediment properties brogger peninsula svalbard abstract georadar and sedimentological data were acquired in the ny alesund area on brogger peninsula in order to study diamicton in frontal areas of vestre broggerbreen and midre lovenbreen parallel common offset georadar lines were acquired for information on thickness and layering and multioffset measurements served to deduce the subground velocity short permafrost cores

is holocene storm generated stratification in florida bay a reflection of solar storm cycles a descriptive analysis of surficial sediments of crane key florida bay showed that the sediments consist of storm layers winter storm and hurricane deposits and algal laminated sediments storm layers are riddled with the following types of cavities gas escape vugs dissolution vugs burrows rootholes and cryptalgal vugs structures and sediment types are arranged into a 15 cm thick thickening upward storm generated sequence which formed in approximately 100 yr under a deepening trend periodograms of sea level variations match the frequency distribution of strong intensity storms which occurred in south florida since the beginning of this century the calculated recurrence time of strong storms 10 3 yr and the time interval of formation of the sequence 100 25 yr are probably a response of climatic parameters to short period 11 yr and longer period 90 110 yr cycles of solar activity comparison with the ancient record shows analogous dm thick storm generated sequences probably linked to solar cycles and 102 yr sea level rises

magnesian calcite and chamositic ooids forming shoals peripheral to late ordovician ashgill muddy siliciclastic shores southern ontario in southern ontario ooids are associated with two distinct facies associations in the queenston formation the final stage of late ordovician ashgill taconic basin fill one facies consists of thin ooid and bioclastic grainstones interbedded with mudrock and lies near the base of the formation and in southwestern ontario also forms a local nw thickening wedge near the middle of the formation ooids have radial fibrous and radial concentric fabrics type a with chamosite illite and fe oxide laths at intercrystalline sites vertical lithologic and ooid abundance patterns indicate that thresholds to carbonate production were sensitive to changes in terrigenous sediment supply sea level circulation accommodation space and tectonism ooids in the second facies association are admixed with abraded fragments of open marine biota or occur burrow fills within a 30 cm thick interval of mudrock near the top of the preserved queenston succession a few metres below the ordovician silurian unconformity ooids have radial concentric and crosscutting patchy microcrystalline fabrics type b this unit may represent a transgressive or stillstand deposit modified by bioturbation the extent of preserved fabric suggests that both ooid types were originally magnesian calcite but type a ooids underwent greater burial alteration this is shown by crystalline mosaics that cross cut relict primary fabrics 13c values 1 82 to 0 67 and 18o values 4 46 to 10 57 more negative than marine calcite of similar age mn and fe concentrations more elevated above expected marine values and a luminescence similar to that of intergranular cements burial meteoric diagenesis was likely promoted by excellent permeability of the host sand we interpret authigenic chamosite and fe oxide to reflect diagenesis of iron bearing and clay detritus trapped during ooid growth type b ooids suffered less alteration 13c 1 1 to 6 64 and 18o 3 04 to 4 81 values overlap the expected marine range including 13c enrichment that occurs within the hirnantian latest ordovician excursion although mn and fe values are still higher than those of modern calcitic ooids negligible luminescence suggests that recrystallization occurred in the presence of marine derived pore fluids further burial alteration was inhibited due to low permeability of the host mud type a ooid facies in the queenston formation forms an ancient analogue for lesser known quaternary ooid shoals peripheral to tropical deltaic systems the facies of type b ooids while more enigmatic may preserve a geochemical herald of latest ordovician climate change the presence of minor chamosite in type a ooids defines a possible distal facies of the well known oolitic ironstones of similar age in the mid continental usa

holocene late pleistocene non tropical carbonate sediments and tectonic history of the western rift basin margin of the southern gulf of california abstract using high resolution seismic reflection profiling and dating of 1 shallow marine vibracores and 2 sediments collected from uplifted marine terraces we reconstruct the tectonic history and sediment accumulation patterns of holocene to late pleistocene warm temperate to subtropical carbonates in the southern gulf of california mexico the study was conducted in the vicinity of la paz where carbonates form along the fault bounded narrow western shelf of the tectonically active gulf of california rift basin the non tropical nature of the setting is responsible for 1 poor cementation of the bioclastic carbonates and 2 a composition which is dominated by rhodoliths coralline red algae corals and mollusks unrimmed carbonate flats forming in small pocket bays and a rhodolith bioherm which has a surface area of more than 20 km2 and is up to 16 m thick constitute the major carbonate factories holocene carbonate accumulation rates were deduced from seismic and core data and are highest on the rhodolith bioherm 260 cm ka and in subtidal zones of pocket bays 210 cm ka and lowest on the inner and middle shelf 100 cm ka taken together rates of carbonate accumulation are intermediate in magnitude between higher rates recorded in fully tropical carbonate settings and lower rates typical of cool water carbonates seismic reflection profiles demonstrate that isla espiritu santo in the center of the study area is a west dipping fault block which is tectonically influenced by two distinct faults the la paz and espiritu santo faults the latter fault accommodates at least 700 m of east side down normal offset and forms a steep eastern escarpment leading into the la paz slope basin some of the sediments produced in the shallow carbonate factories of the narrow la paz shelf are transported across this escarpment and are redeposited in the slope basin at a water depth of 750 m uranium series dates of marine terraces exposed on isla espiritu santo indicate that late pleistocene uplift along the eastern side of the island could be as high as 310 mm ka whereas downdropping along the western side of the island occurred at a rate of up to 15 mm ka isla espiritu santo therefore constitutes part of the uplifted shoulder of the western margin of the gulf of california rift basin patterns of vertical tectonic movements of isla espiritu santo together with fault offsets on the surrounding seafloor and slump features on steep submarine slopes point to continuous activity of the la paz and espiritu santo faults results of this study will assist in recognizing and interpreting similar settings along ancient non tropical rift basin margins worldwide and especially in the neogene of the gulf of california

palaeobathymetric reconstruction of peritidal carbonates late barremian urgonian sequences of provence se france abstract peritidal platform carbonates of late barremian age early cretaceous cropping out in the marseille region provence se france tend to be arranged stratigraphically in deepening up or shallowing up sequences seven facies types lithofacies were defined in the studied stratigraphic interval ranging from supratidal to shallow subtidal settings there is a good correspondence between the inferred relative water depth of facies and their average bed thickness cumulative thickness of facies types expresses quantitatively their palaeobathymetric range and provides an estimate of their average water depth calculations show that the palaeobathymetry of supratidal intertidal facies types is from 0 to 40 cm i e a pertaining to a palaeotidal microtidal range the average palaeobathymetry of rudist facies ascribed to subtidal settings fluctuates between 40 cm and nearly 160 cm measuring a large number of beds belonging to both shallowing up and deepening up sequences and averaging the results appear relevant to minimise the effect of compaction pressure solution and synsedimentary progressive or abrupt changes in accommodation which are expected to modify bed thickness and its original palaeobathymetric significance the method proposed here has a good potential for palaeobathymetric reconstruction of ancient peritidal carbonates

soft sediment deformation structures in cambrian siliciclastic and carbonate storm deposits shandong province china differential liquefaction and fluidization triggered by storm wave loading abstract this paper focuses on soft sediment deformation structures ssds in both siliciclastic and carbonate storm deposits of the cambrian mantou and chaomidian formations shandong province china in order to understand their deformation mechanisms and possible triggers siliciclastic ssds e g sand volcanoes and pillows and carbonate ssds e g sedimentary dykes grainstone matrix breccias deformed cross beddings and marlstone matrix breccias occur exclusively in hummocky cross stratified fine sandstone and peloidal grainstone respectively the siliciclastic ssds formed in porous and permeable surface sediment whereas the carbonate ssds formed under shallow burial conditions when early marine cementation prevailed the various deformation structures resulted mainly from differences between siliciclastic and carbonate sediment conditions and resulting deformation mechanisms sand volcanoes formed by upward extrusion of over pressured fluidized sandy sediment whereas sand pillows resulted from upward injection of lower density muddy sediment into overlying liquefied sandy sediment sedimentary dykes and grainstone matrix limestone breccias formed as a result of differential liquefaction and fluidization of heterogeneously cemented carbonate sediment whereas deformed cross beddings and marlstone matrix limestone breccias developed by the thixotropic liquidization and injection of clayey sediment and further disruption of thin peloidal layers sedimentary facies analysis and analysis of the physical processes indicate that the ssds were most likely caused by cyclic loading of storm waves

continuous and simultaneous measurement of reflector depth and average soil water content with multichannel ground penetrating radar ground penetrating radar is a fast noninvasive technique that can monitor subsurface structure and water content distribution to interpret traveltime information from single common offset measurements additional assumptions such as constant permittivity usually are required we present a fast ground penetrating radar measurement technique using a multiple transmitter and receiver setup to measure simultaneously the reflector depth and average soil water content it can be considered a moving minicommon midpoint measurement for a simple analysis we use a straightforward evaluation procedure that includes two traveltimes to the same reflector obtained from different antenna separations for a more accurate approach an inverse evaluation procedure is added using traveltimes obtained from all antenna separations at one position and its neighboring measurement locations the evaluation of a synthetic data set with a lateral variability in reflector depth and an experimental example with a large variability in soil water content are introduced to demonstrate the applicability for field scale measurements the crucial point for this application is the access to absolute traveltimes which are difficult to determine accurately from common offset measurements

short pulse radar detection of groundwater in the sagavanirktok river floodplain in early spring short pulse radar operating in the uhf band was used to search for unfrozen water beneath ice blisters and within the gravels of the sagavanirktok river floodplain near prudhoe bay alaska the investigations were carried out in early april 1991 when daily mean air temperatures still were below 20 c the radar pulse spectrum was centered near 400 mhz and the radar time range was set to cover about 10 m depth the flat snow covered surface allowed good antenna ground coupling and the ice and gravels provided a low loss propagation medium that allowed detail of the gravel structure to be seen in the data grids of several traverses were profiled at three sites all within an area of about 0 5 km2 unfrozen water was inferred from the strength and polarization of the radar reflections one site contained a large icing blister beneath which an extensive reservoir was mapped and seen to extend several tens of meters beyond the mound data from two other sites indicated taliks 5 7 m deep near a frozen mound and within the gravels one of the profiles extended 700 m across the floodplain and revealed other high reflectivity targets which were presumed to be water within about 7 m of the surface a deeper sounding confirmed this depth limit it is concluded that taliks exist in the floodplain throughout the winter and are a probable source for the numerous icing mounds seen along most arctic rivers east of prudhoe bay

lack of impact of hurricane michelle on tidal flats andros island bahamas integrated remote sensing and field observations abstract major storms commonly are cited as important geomorphic and sedimentologic agents and their significance is perhaps most emphatically noted in interpretations of modern and ancient tidal flats the purpose of this study was to assess the impact of hurricane michelle on the carbonate tidal flats of andros island bahamas by coupling remote sensing data and field observations although regional modis remote sensing data reveal that the passage of hurricane michelle suspended sediments across the shallow bank integrating ultra high resolution remote sensing data with field observations demonstrates that the hurricane had almost no impact on the andros island tidal flats this lack of impact is surprising because the storm still had hurricane force winds as it passed immediately over some of the focal areas with this hurricane storm strength and intra storm interval were probably not limiting factors instead several influences combined to minimize the storm s impact on both sedimentation and erosion including the low level of water on the bank resulting from ebb tides and in the northwestern area from offshore storm winds and the short duration of the storm resulting from its high forward velocity given the apparent prevalence of widespread storm effects on ancient tidal flats but the spatially limited major geomorphic impacts of storms on many modern systems we suggest that the geologic evolution and preservation of ancient tidal flat successions may have been shaped by mega storms that simply cannot form in the present global climate nonetheless understanding tidal flat dynamics and changes on human timescales will require continued monitoring and assessment of low impact storms such as michelle as well the more sensational hurricanes that produce widespread death destruction and deposition

blackriveran carbonates from the subsurface of the lake simcoe area southern ontario stratigraphy and sedimentology of a low energy carbonate ramp the lowest upper ordovician blackriveran strata in the lake simcoe area represent the base of a major transgressive sequence of peritidal carbonates and siliciclastics from detailed petrographic

geologic impact of hurricane andrew on everglades coast of southwest florida hurricane andrew one of the strongest storms of the century crossed the southern part of the florida peninsula on 24 august 1992 its path crossed the florida everglades and exited in the national park across a mangrove dominated coast onto the shallow low energy inner shelf the storm caused extensive breakage and defoliation in the mangrove community full recovery will take decades it produced no extensive sedimentation unit only local and ephemeral ebb surge deposits the discontinuous shelly storm beach ridge was breached at multiple locations and it moved landward a few meters after seven months there was little geologic indication that the storm had passed it is likely that the stratigraphic record in this area will not contain any recognizable features of the passage of hurricane andrew

ground penetrating radar reflection profiling of groundwater and bedrock in an area of discontinuous permafrost we have used ground penetrating radar to profile the depth of permafrost to groundwater beneath permafrost and to bedrock within permafrost in alluvial sediments of interior alaska we used well log data to aid the interpretations and to calculate dielectric permittivities for frozen and unfrozen materials interfaces between unfrozen and frozen sediments above permafrost were best resolved with wavelet bandwidths centered at and above 100 mhz the resolution also required consideration of antenna configuration season and surface conditions depths to subpermafrost groundwater were profiled where it was in continuous contact with the bottom of the permafrost except near transitions to unfrozen zones where the contact appeared to dip steeply the complexity of the responses to intrapermafrost bedrock detected at a maximum depth of 47 m appears to distinguish these events from those of subpermafrost saturated sediments the relative dielectric permittivity ranged between 4 4 and 8 3 for the permafro

hurricane deposits on carbonate platforms a case study of hurricane irma deposits on little ambergris cay turks and caicos islands the study of modern hurricane deposits is useful in both identifying ancient hurricane deposits in the rock record and predicting patterns of deposition and erosion produced by future storm events hurricane deposits on carbonate platforms have been studied less frequently than have been those along continental coasts here we present observations of the characteristics of deposition and scour caused by hurricane irma on little ambergris cay a small uninhabited island located near the southeastern edge of the caicos platform in the turks and caicos islands hurricane irma passed directly over little ambergris cay on 7 september 2017 as a category 5 hurricane we described and sampled multiple types of hurricane deposits and determined that the washover fans were the best sedimentological records for hurricane conditions as they were subject to very little reworking over time we compared different model predictions of storm tide and wave height with eyewitness reports and distributions of scour examining the washover fans allowed for the construction of a conceptual model for hurricane deposits formed in a high energy storm event on a carbonate platform characteristics of the washover fans were their small size the lack of sedimentary structures and very well sorted sediment the size and distribution of carbonate boulders eroded and transported by the storm are consistent with depth averaged flow velocities in the range of 1 5 5 3 m s the strength of the storm and the low lying topography distinct features of a carbonate platform setting contributed to high levels of sediment bypass and high flow velocities resulting in small unstructured deposits

an extensive erosion surface of a strongly deformed limestone bed in the gushan and chaomidian formations late middle cambrian to furongian shandong province china sequence stratigraphic implications abstract in order to understand sequence development and sea level fluctuations during the late middle cambrian to early furongian on the north china epeiric platform the present study focuses on a unique subtle erosion surface of an extensive approx 100 km strongly deformed limestone bed in the uppermost part of the gushan formation shandong province china the gushan formation and the overlying chaomidian formation consist mainly of shales and a variety of carbonates that were deposited in subtidal environments e g deep subtidal shallow subtidal shoreface shoal subtidal microbial flat and restricted platform interior three third order depositional sequences s1 3 are identified each of which comprises a thin transgressive systems tract tst and a relatively thick highstand systems tract hst each sequence is bounded by a drowning unconformity sb1 a subaerial unconformity sb2 or a surface of submarine erosion sb3 the upper sequence boundary sb2 of sequence 1 s1 is represented by a subtle erosion surface of an extensive deformed limestone bed with a wide variety of soft sediment deformation structures e g lime mudstone breccias chaotic wacke packstone laminae and fragments homogenized oolites and clastic dykes and is overlain by small sporadic microbial buildups and an extensive bioclastic grainstone bed the deformed limestone was formed during early diagenesis by differential deformation processes brecciation liquefaction fluidization and injection which were most likely induced by pore water overpressure during the period of rapid sea level fall despite the lack of subaerial exposure features e g paleokarst paleosol etc the characteristics of the erosion surface cutting well lithified sediment below the missing of a significant geological record the prochuangia biozone and the worldwide correlatable positive carbon isotope excursion collectively indicate that the erosion surface developed under conditions of subaerial exposure after contemporaneous marine cementation of the deformed sediment the missing of the prochuangia biozone is most likely due to non deposition at a subaerial hiatal surface the erosion surface was submerged as a result of subsequent rise in sea level where sporadic microbial buildups formed under suitable conditions freshly deposited winnowed shell dominated transgressive lag deposits containing chuangia trilobite fragments brachiopod shells and abundant glauconite grains formed with continued rise in sea level which became in turn overlain by shale dominated facies the unique combination of the subtle erosion surface sensu stricto a subaerial unconformity and the underlying deformed limestone bed provides an important criterion for recognizing the subtle changes in relative sea level on shallow epeiric platforms

impact of dynamic sedimentation on facies heterogeneities in lower cretaceous peritidal deposits of central east oman this study based in the haushi huqf area of central east oman aims to characterize the controls on facies distribution and geometries of some of the best preserved examples of lower cretaceous tidal flat facies within the tethyan epeiric platform field petrographic and geochemical data were acquired from the barremian aptian jurf and qishn formations that crop out in a 500 1000 m2 butte thus allowing for pseudo three dimensional quantitative data acquisition of the dimensions and spatial distributions of discontinuity surfaces and sedimentary bodies the interpretation presented here suggests that the main processes impacting sedimentation in the lower cretaceous peritidal environment of the haushi huqf were transport and erosion processes related to storm waves and currents the vertical evolution of the carbonate system is organized into six types of metre scale depositional sequences from subtidal dominated sequences to supratidal capped sequences which are bounded by regional discontinuity surfaces at subaerial exposure and submarine erosion surfaces associated with a base level shift sedimentary horizons along the entire depositional profile are cut by scours possibly created by storm events chemostratigraphy allows correlation between the haushi huqf and the age equivalent sections logged in the interior of the platform in oman the correlation suggests that the change from subtidal to intertidal depositional sequences during the late highstand is coeval with the development of rudist dominated shoals on the shelf this study is the first to discuss the controls on lower cretaceous peritidal carbonate cyclicity of the arabian epeiric platform the results presented here also offer a unique quantitative dataset of the distribution and dimensions of peritidal carbonate shoals and storm scours in a regional sequence stratigraphic context

depletion of heavy rare earth elements in metamorphic minerals from adirondack anorthosites repartitioning of rare earth elements ree during the grenville granulite facies metamorphism of adirondack anorthosite has produced metamorphic minerals depleted in the heavy ree relative to concentrations predicted by igneous partition coefficients the heavy ree depletion is observed in garnet bearing metamorphosed anorthosites and results from closed system repartitioning of ree among heavy ree rich garnet and other recrystallizing minerals the resulting heavy ree depleted patterns contrast with primary igneous mineral patterns which conform to predictions from igneous partition coefficients whole rock ree patterns of adirondack anorthosites are not affected by the local ree rearrangement anorthosite ree patterns reflect their primary igneous mineralogy and are independent of any secondary metamorphic minerals formed during the grenville metamorphic event consequently the ree did not move more than a few centimetres during the granulite facies metamorphism

ichnology and depositional environments of the upper ordovician stony mountain formation in the williston basin canada refining ichnofacies and ichnofabric models for epeiric sea carbonates abstract ordovician epeiric sea carbonates in intracratonic basins of laurentia are enigmatic due to their unique depositional settings and the absence of modern analogs integrated ichnologic and sedimentologic analysis of the upper ordovician stony mountain formation in the williston basin of canada allows recognition of neritic marine nearshore marine open lagoon restricted lagoon peritidal sand shoal and peritidal flat subenvironments the cruziana ichnofacies occurs in neritic between fair weather and storm wave bases and nearshore around fair weather wave base marine environments the depauperate cruziana ichnofacies is present in open and restricted lagoon environments indicating a shift from fully marine to stressed conditions in the open lagoon composite ichnofabrics related to omission surfaces illustrate the low rates of background sedimentation interrupted by event deposition and early cementation illustrating the glossifungites and trypanites ichnofacies the decreased size of discrete burrows in the restricted lagoon is attributed to reduced oxygenation under stagnation rather than hypersalinity the peritidal complex includes high energy sand shoals and low energy tidal flats only monospecific colonization took place sporadically in associated subtidal environments within the peritidal complex deposits

tidal flat sedimentation from hurricane kate caicos platform british west indies abstract hurricane generated thinly bedded grainstones are the dominant style of stratification on the carbonate tidal flat complex on caicos platform british west indies this is in dramatic contrast to the winter storm generated millimeter thick laminae which dominate stratification on the northwest andros tidal flats and have become the general criteria for recognizing ancient carbonate tidal flat sequences hurricane kate which passed directly across the caicos tidal flats on 18 november 1985 provided an opportunity both to document the character and distribution of a specific storm sediment layer and to evaluate the role of hurricanes in molding the geometry of the tidal flat system though moderate in strength and producing only incomplete flooding hurricane kate deposited a layer of fine to very fine peloidal grainstone 0 5 2 cm in thickness across significant portions of the extremely broad low relief shore and channel levees and the inland algal marsh these storm layers are interbedded with organic rich layers which represent prolonged periods of growth of scytonema algal mat between hurricanes recognition that centimeter thick grainstone layers dominate entire tidal flat complexes necessitates both a thorough modification of criteria for defining ancient carbonate tidal flat deposits and a reevaluation of supposedly subtidal thinly bedded limestones

measuring thaw depth beneath peat lined arctic streams using ground penetrating radar in arctic streams depth of thaw beneath the stream channel is likely a significant parameter controlling hyporheic zone hydrology and biogeochemical cycling as part of an interdisciplinary study of this system we conducted a field investigation to test the effectiveness of imaging substream permafrost using ground penetrating radar gpr we investigated three sites characterized by low energy water flow organic material lining the streambeds and water depths ranging from 0 2 to 2 m we acquired data using a 200 mhz pulsed radar system with the antennas mounted in the bottom of a small rubber boat that was pulled across the stream while triggering the radar at a constant rate we achieved excellent results at all three sites with a clear continuous image of the permafrost boundary both peripheral to and beneath the stream our results demonstrate that gpr can be an effective tool for measuring substream thaw depth copyright 2005 john wiley sons ltd

karst and early fracture networks in carbonates turks and caicos islands british west indies abstract historically studies of quaternary carbonates have not adequately addressed the influence of early fracture networks on diagenesis because of this lack of detail understanding and predicting fracture related diagenetic heterogeneities and preferential fluid flow pathways in ancient carbonate successions is particularly challenging the pleistocene oolitic grainstones of the caicos platform provide an excellent opportunity to evaluate the relative importance of fractures on early diagenetic alteration styles and are a suitable analog for subsurface carbonate reservoirs detailed analyses of fractures e g orientation aperture spacing fill material from caicos outcrops combined with high resolution three dimensional ground penetrating radar 3d gpr assisted in exploring the causality and distribution of fractures and relationship to karst four models were evaluated to explain the observed distribution of dolines 1 gravitational fractured margin controlled 2 tectonic fracture controlled 3 antecedent topography controlled and 4 a hybrid model based on observations of numerous fractures n 306 on the western caicos platform early fractures are abundant and dominantly margin parallel these fracture networks are well established in limestones prior to mineralogical stabilization thereby indicating that diagenetic heterogeneities evolve very early in carbonate diagenesis the spatial distribution of dolines on providenciales is likely the result of a complex interplay between the antecedent topography margin parallel fracture systems and meteoric fluids resultant diagenetic alteration is far more complicated than simple unconfined meteoric lenses associated with topographic highs any attempts to model early diagenesis in carbonates should not dismiss the role of fractures as diagenetic facilitators and diagenetic anisotropy templates

sedimentology of an early silurian carbonate ramp the manitoulin formation southern ontario the manitoulin formation is a pervasively dolomitized lower silurian carbonate unit that was deposited in the michigan basin and locally in the appalachian basin the formation reaches a maximum thickness of 11 1 m in southern ontario and can be subdivided into eight facies and four regionally correlatable facies assemblages owing to the relatively continuous transition of shallow to deeper water facies from the northern to southern portions of the study area the manitoulin formation is interpreted as having formed on a carbonate ramp with a southerly component of dip our study suggests that the algonquin arch which is transected by the outcrop belt did not significantly influence deposition or separate the michigan and appalachian basins depending on its location on the ramp the manitoulin formation shows evidence of varying degrees of episodic storm events alternating with fair weather processes such as wave shoaling sediment reworking and bioturbation apart from bioturbation these fair weathe

shallow marine and coastal eolian quartz arenites in the neoarchean palaeoproterozoic karutola formation dongargarh volcano sedimentary succession central india abstract the neoarchean palaeoproterozoic karutola formation a 200 m thick supermature quartz arenite occurs interlayered between two thick units of intermediate to basic volcanic rocks of the dongargarh group despite metamorphism and deformation detrital texture and sedimentary structures are well preserved allowing detailed process based facies analysis the facies recognised include 1 inner shelf 2 shoreface 3 delta mouth lower delta plain 4 tidal flat and 5 foreshore backshore a coastal sand sheet dominated by adhesion structures and consisting of alternating eolian and foreshore aqueous deposits records eolian processes operative in the karutola coastal area textural characteristics hint at a significant eolian contribution to the shallow marine sand overall palaeocurrent indicates a nw se shoreline trend with hinterland to the west of the present outcrop belt a surface indicating an abrupt increase in the water depth divides the formation into two units the lower part encloses inner shelf to foreshore backshore deposits and the upper part of the succession records deposition from the shoreface to lower deltaplain environment a tidal flat sandstone mudstone unit is developed only in the north western end of the study area a granite gneiss source terrain cropping out to the west and a hot humid climate appears to have supplied the abundant quartz sand to the karutola shoreline and the sand population attained textural maturity through eolian and aqueous reworking it is postulated that the aqueous eolian interaction inferred for the karutola sand should be common in sandy depositional environments that lacked land vegetation