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1.
Limestone neutralization of the acidic water of Dog-way Fork in West Virginia resulted in significant improvements in both water quality and fish populations. Pretreatment water chemistry showed the stream to be highly acidified by acid precipitation, with pH under 5.0 and high aluminum concentrations. During treatment, the goals for the target area of pH 6.5 and acid-neutralizing capacity of 50 μmeq/L were met for 75.8% and 67% of the time, respectively. A pH 6.0 or above was maintained over 93% of the time. Monomeric aluminum concentrations were reduced significantly, and calcium to hydrogen ionic ratios were over 10 in the target area. Prior to treatment, no resident fish population was found in Dogway Fork. During five years of treatment, conditions were favorable for fish reproduction and survival. Eight fish species inhabited the stream, six were reproducing there, and a fishable brook trout population was established.  相似文献   

2.
The unusual form of sexual signaling, the drumming producedby the wolf spider Hygrolycosa rubrofasciata, allows exceptionallydetailed studies of female preference patterns against signalcharacteristics. It is easy to manipulate the signals and touse large numbers of females in playback experiments. Malesof H. rubrofasciata produce drums by striking their abdomenagainst dry leaves on the ground. Drums travel not only as substrate-borne vibrations, but also as airborne acoustic signals.Females respond sooner to drums transferred as substrate borne,but the mode of signal transfer has no effect on female preferencefor different types of drums. We investigated the effects oftwo key components of the drums, duration and pulse rate, onfemale choice. Previous studies have shown that the durationof the drum is both repeatable within males and variable betweenmales. In contrast, pulse rate shows high within-male repeatabilitybut only little variability between males. Using playbacksof manipulated drums, we found that females preferred drumsof longer duration but that pulse rate had no effect on femalepreference. Our results suggest that drum duration may functionas an indicator of male quality for choosy females. Pulse rate,on the other hand, is less likely to be an important traitin intersexual selection. Female preference for drum durationwas open-ended within the natural variation of the drum durations,but it leveled off outside the normal range. Thus supernomalstimuli would not pay for males using this energetically demanding acoustic signal.  相似文献   

3.
Mathematical considerations of the behavior of aerosolized particles in a rotating drum are presented, and the rotating drum as an aerosol-holding device is compared with a stirred settling chamber. The basic overall design elements of a facility employing eight rotating drums are presented. This facility provides an environment in which temperature can be maintained within 0.5 F (0.25 C) of any set point over a range of 50 to 120 F (10 to 49 C); concomitantly the relative humidity within any selected drum may be controlled in a nominal range of 0 to 90%. Some of the major technical aspects of operating this facility are also presented, including handling of air support systems, aerosol production, animal exposure, aerosol monitoring, and sampling.  相似文献   

4.
Calcium carbonate gel therapy for hydrofluoric acid burns of the hand   总被引:2,自引:0,他引:2  
Hydrofluoric acid is used extensively as an industrial cleaning agent for metals and glass. Many workers are injured by cutaneous contact of the acid with exposed skin surfaces, particularly hands. Hydrofluoric acid burns are characterized by delayed onset of symptomatology with skin ulceration, and severe pain may be of extended duration. Treatment of hydrofluoric acid burns traditionally has consisted of local infiltration or intraarterial injections of calcium solutions. These injections are painful and frequently require retreatment. A new treatment utilizing a topical gel of calcium carbonate is described. Nine patients have been treated for hydrofluoric acid burns of the hand with calcium carbonate gel applied topically and covered with occlusive glove dressings. A gel slurry is compounded from calcium carbonate tablets and K-Y Jelly. Fingernails of the affected fingers are removed if a subungual burn is obvious. The gel is put into a surgeon's glove and placed over the burned hand. The patient replaces the glove and slurry every 4 hours for 24 hours. After the first day, the glove is discontinued unless there is resumption of painful symptoms. Full range of motion is encouraged during this interval. The calcium carbonate gel technique was successfully utilized in nine patients with no further need for injection therapy. In these patients, pain relief was obtained within 4 hours of treatment, with no further progression of skin ulceration. No reconstructive procedures were required in any patient, and only one patient did not return to full-duty work within 1 week. There were no long-term sequelae from burns treated with this topical therapy, except one patient, who presenting 24 hours after the burn, developed a digital tip neuroma that was excised.  相似文献   

5.
Two different formaldehyde-degrading microorganisms, Pseudomonas putida and Methylobacterium extorquens, were isolated from calcium carbonate slurry containing the formaldehyde-releasing biocide (ethylenedioxy) dimethanol. Their relative formaldehyde biodegradation and formic acid production kinetics were studied in broth and in calcium carbonate slurry for each microorganism individually, as well as in mixed cultures. Furthermore, the minimal inhibition concentration (MIC) was determined. The results indicated that in slurry, M. extorquens is more tolerant of formaldehyde than P. putida. In slurry, microbial-induced oxidation of formaldehyde caused a temporary accumulation of formic acid, which is presumed to be responsible for pH drop and destabilisation of the calcium carbonate slurry suspension systems. In addition, the residual formaldehyde concentration was observed to drive dominance and recovery of individual formaldehyde-resistant microorganisms in the slurry. Overall, this investigation indicated that biodegradation of formaldehyde in calcium carbonate slurry is brought about by alternating dominance of bacterial genera of mixed formaldehyde-resistant microbial populations.  相似文献   

6.
The aim of this study was to analyze the bacterial community in the production line of a calcium carbonate filler production company and to investigate possible causes for bacterial presence. Throughout 2012, 24 carbonate slurry and six groundwater samples were analyzed. Pseudomonas and Microbacterium were the most frequent contaminants in the slurry, whereas Pseudomonas and Brevundimonas dominated the groundwater samples. Of the 43 different bacterial strains isolated, only five were found both in the slurry and the groundwater, indicating that the latter was not a major source of contamination. The efficacy of 54 commercial biocidal formulations was tested against an artificial bacterial consortium composed of selected slurry isolates. A formulation containing 7.5–15% (v v–1) bronopol and 1.0–2.5% (v v–1) [chloroisothiazolinone (CIT) + methylisothiazolinone (MIT)] exhibited the highest efficacy. Of the possible causes for bacterial presence, sporogenesis and biocide adsorption to carbonate particles were found to be less probable compared to bacterial adsorption to particles, and the acquisition of resistance to biocides.  相似文献   

7.
Thanetian–Ilerdian carbonate deposits from the Lakadong Limestone in Assam Shelf, Meghalaya, northeast India, are studied with respect to microfacies distributions and controlling ecological factors on dominant biogenic components. Palaeoenvironmental implications are inferred following the detailed analysis of microfacies characterized by rich assemblages of coralline red algae and benthic foraminifera. The carbonate sediments have been interpreted as lagoonal to outer shelf facies. It is envisaged that the analysed benthic communities thrived in a meso‐oligotrophic regime above the fair‐weather wave base. The Lakadong Limestone constitutes a well‐preserved record of Late Palaeocene–earliest Eocene shallow marine carbonate ecosystem and has high potential to decipher its response to an interval of distinct changes in climate and tectonic settings. The abundance of oligotrophic larger benthic foraminifera in the Lakadong Limestone is comparable to the foraminiferal assemblages of west Tethys. The phylogenetic changes (‘Larger Foraminiferal Turnover’, LFT) and subsequent rapid radiation of typical Eocene larger benthic foraminifera (Alveolina, Nummulites) usually observed in the west Tethys have also been observed in the upper part of the Lakadong Limestone. The eastward migration of Eocene foraminifera from the west coincided with the India‐Asia collision and global warming events at the Palaeocene–Eocene boundary that may have produced a wide array of modifications in biogeography, seasonal run‐offs and ocean circulation pathways. The data indicate that rapid rate of migration from west before the onset of geographic barriers and/or timely restoration of pan‐Tethyan environmental conditions ensured the incidence of these forms in the earliest Eocene sediments.  相似文献   

8.
The relationship between the paleocurrent pattern and the paleoslope in several continental and marine environments has been reviewed. This relationship in shelf sediment is not adequately established, and appears to be more complex than is now understood. The paleocurrent pattern of the Mississippian Loyalhanna—Trough Creek Limestone (a shelf calcarenite) is presented here as a case study. The study shows that the sediment dispersal system and the current pattern are independent of the paleoslope, and that the vector orientation is polymodal. It is, however, argued that before a precise paleocurrent model for shelf carbonate is formulated, more investigation in recent and ancient rocks is necessary.  相似文献   

9.
Summary  Biohermal and biostromal buildups were investigated in late Early and Middle Devonian carbonate complexes of the Tamworth Belt. The buildup types and subtypes were studied in three regions (Yarramanbully, Sulcor and, Wyaralong') to clarify their paleo-environmental position. Two stages of development are recognized: Incipient bioherms and bioherms. Incipient bioherms are carbonate buildups with organisms which commonly form true bioherms. They dominate the sediment with small growth forms but are not prolific enough to build large bio-frameworks. Small nodular and globular stromatoporoids characterize the incipient bioherms and are interpreted as stunted growth forms. In one location (‘Wyaralong’) the coarse stromatoporoid calcarenite represents a fore-reef facies, at Sulcor a shallow subtidal setting with moderate water energy can be deduced. The bioherms can be sub-divided into stromatoporoid-, stromatoporoid-Stachyodes-, and stromatoporoid-rugose coral bioherms. Their variable composition probably reflects growth and deposition in different zones of a reef complex and/or different proximity to areas of denundation indicated by high siliciclastic input. In the Tamworth region true bioherms occur only in the Moore Creek Limestone Member (Middle Devonian), and not in older carbonate successions. Biostromes are sub-divided into (1) incipient biostromes with stromatoporoid-heliolitid biostromes and alveolitid biostromes; (2) aggregate biostromes withAmphipora andStachyodes biostromes; (3) stratified biostromes; (4) mixed aggregate/stratified biostromes. The different types of biostromes are not limited to specific time-intervals, but rather to environmental conditions.
(1)  Incipient biostromes are characterized by laminar stromatoporoids and tabulate corals. Their forms are interpreted as initial layers of skeletons which were hampered by adverse conditions in growth. The stromatoporoid-heliolitid incipient biostrome (Eifelian Moore Creek Ls. Mbr., Yarramanbully) is characterized by abundance of dislodged laminar, ragged and tabular colonies associated with small globular and nodular heliolitids. An unstable substrate may have caused the growth disruptions. Decreasing grain-size of skeletal debris and increasing mud-content suggests deposition on a bathymetric gradient with deepening to the south. The alveolitid incipient biostrome (Eifelian Moore Creek Ls. Mbr., ‘Wyaralong’) is composed of nodular limestone with laminar alveolitids, stromatoporoids andSphaerocodium. It grades eastwards into dark nodular limestone with siliceous sponges and westwards it interdigitates with mudrich calcarenite. Deepening from west to east is implied. The incipient biostromes are interpreted as foreslope facies deposited at depths ranging from shallow subtidal (coarse-grained calcarenite) to deeper subtidal (fine-grained mud-rich calcarenite).
(2)  The term ?aggregate biostromes? is chosen to characterize large mono-or oligo-generic aggregations of sessile colonial animals with calcareous skeletons with ramose growth habit examplified byAmphipora- andStachyodes biostromes. Both genera of ramose stromatoporoids lived in quiet shallow subtidal environments, withAmphipora apparently enduring higher mud contents and possibly hypersalinity and/or oxygen deficiency.
(3)  Stratified biostromes are built mainly by tabular and laminar stromatoporoids and tabulate corals. Only one example from the Sulcor Limestone Member can be recognized in the Tamworth region. These deep and quiet water buildups formed when sedimentation rate was low. Possibly they indicate drowning of the carbonate platform.
(4)  Mixed stratified/aggregate biostromes are also deep water carbonate buildups. They exhibit an alternation of growth forms (ramose and stratified) at different levels. The mixed biostromes at yarramanbully (Emsian) show alternating growth habits varying in 50 m to 60 m-intervals from stratified growth form-dominated to aggregate growth form-dominated to mixed buildup facies. Sea level changes due to tectonism or orbital changes may be the cause. Small scale cyclic alternations of growth forms occur in irregular (decimeter) intervals in the Yarramanbully biostromes and in more regular intervals in Eifelian mixed stratified/aggregate biostromes. Possible control factors include sea-level or climatic changes and faunal interactions.
Bioherms and aggregate biostromes with ramose stromatoporoids are interpreted as-shallow water deposits, whereas the biostromes formed in deeper water. This differentation is crucial for reconstruction of the depositional history of the basin. Association of biohermal limestone with aggregate biostromes (i.e.Amphipora- andStachyodes limestone) reflects differentiation of a carbonate platform into reef and quiet water off-reef depositional centres. The sporadic development of deep-water buildups signals deposition over an increasing relief possibly caused by tectonism.  相似文献   

10.
有机污染土壤生物修复的生物反应器技术研究进展   总被引:5,自引:2,他引:3  
人类广泛的工农业生产活动常常导致土壤污染。常见的土壤污染有重金属污染和有机污染。近年来 ,世界各国开始重视污染土壤的治理。处理方式主要包括热处理 (焚烧法 )、物理及物理化学处理(洗涤 )和生物处理 (生物修复技术 )。其中生物修复技术被认为最有生命力[1,7] 。目前 ,国外采用的土壤生物修复技术有原位处理、场上处理和生物反应器。生物反应器技术能够有效地发挥生物法的特长 ,是污染土壤生物修复技术中最有效的处理工艺 ,但该技术尚处于实验室研究阶段 ,未广泛应用于现场处理。本文就国外使用生物反应器治理有机污染土壤的研究进展…  相似文献   

11.
Summary The Sikhor Formation (new) is a predominantly siliciclastic sediment package intercalated between the marly-silty Baghamshah Formation (below) and the calcareous Esfandiar Limestone and Qal'eh Dokhtar Limestone formations (above). All stratigraphic evidence points to an Early Callovian age of the formation. The Sikhor Formation is restricted to the southern and central Shotori Mountains and consists of two members: The Kuh-e-Neygu Member (new) is composed of fluvialdeltaic conglomerates, sandstones, and siltstones grading into marly silt of the Baghamshah Formation. The overlying Majd Member (new) is characterised by mixed siliciclastic-carbonate sediments that record the interfingering of carbonate ramp sediments with fluvialdeltaic sands and silts. Evidence of erosional truncation of the underlying Baghamshah Formation and confinement of the siliciclastic sediment to a comparatively narrow, NNW-SSE elongated strip suggest that the formation had its origin in the asymmetric uplift of a westdipping tilted fault block in the southern Shotori Mountains that shed its sediment predominantly in a northern and eastern direction. After erosional levelling, the former uplifted areas were overgrown by the highly productive Esfandiar Carbonate Platform. The Sikhor Formation thus is evidence of an extensional tectonic pulse in the early Callovian and underlines that this area of the Tabas Block was a tectonically highly unstable area during most of the Jurassic.  相似文献   

12.
Low volume processing of protein blots in rolling drums   总被引:2,自引:0,他引:2  
We have evaluated an improved method for processing protein blots on nitrocellulose or nylon membranes using cylindrical plastic containers. The method, which is directly analogous to the commonly used method of photographic processing in rolling drums, uses small values of reagents which are constantly washed over the blotting membrane by rotating the drum horizontally on a roller mixer. Volumes of reagents used are typically less than one-10th of those required for conventional methods using plastic bags or trays. The efficiency of probing and washing steps are greatly improved, giving an all-round increase in sensitivity, ease of processing, and economy of reagents.  相似文献   

13.
Summary Following a phase of predominantly siliciclastic sedimentation in the Early and Middle Jurassic, a large-scale, low-latitude carbonate depositional system was established in the northern part of the Tabas Block, part of the central-east Iranian microplate, during the Callovian and persisted until the latest Oxfordian/Early Kimmeridgian. Running parallel to the present eastern block margin, a NNW/SSE-trending carbonate platform developed in an area characterized by reduced subsidence rates (Shotori Swell). The growth of this rimmed, flat-topped barrier platform strongly influenced the Upper Jurassic facies pattern and sedimentary history of the Tabas Block. The platform sediments, represented by the predominantly fine-grained carbonates of the Esfandiar Limestone Formation, pass eastward into slope to basin sediments of the Qal'eh Dokhtar Limestone Formation (platform-derived allochthonites, microbialites, and peri-platform muds). Towards the west, they interfinger with bedded limestones and marlstones (Kamar-e-Mehdi Formation), which were deposited in an extensive shelf lagoon. In a N−S direction, the Esfandiar Platform can be traced for about 170 km, in an E-W direction, the platform extended for at least 35–40 km. The width of the eastern slope of the platform is estimated at 10–15 km, the width of the western shelf lagoon varied considerably (>20–80 km). During the Late Callovian to Middle Oxfordian, the Esfandiar Platform flourished under arid climatic conditions and supplied the slope and basinal areas with large amounts of carbonates (suspended peri-platform muds and gravitational sediments). Export pulses of platform material, e.g. ooids and aggregate grains, into the slope and basinal system are interpreted as highstand shedding related to relative sealevel variations. The high-productivity phase was terminated in the Late Oxfordian when the eastern platform areas drowned and homogeneous deep water marls of the Upper Oxfordian to Kimmeridgian Korond Formation onlapped both the Qal'eh Dokhtar Limestone Formation and the drowned Esfandiar Limestone Formation. Tectonic instability, probably caused by faulting at the margins of the Tabas Block in connection with rotational movements of the east-central Iranian block assemblage, was responsible for the partial drowning of the eastern platform areas. In some areas, relicts of the platform persisted to produce shallow-water sediments into the Kimmeridgian.  相似文献   

14.
Summary New dates and analysis of 12 deep and 57 shallow cores allow a more detailed interpretation of the Pleistocene shelf edge of the Florida Platform as found in various facies of the Key Largo Limestone beneath the Florida Keys. In this study a three-phase evolution of the Quaternary units (Q1–Q5) of the Key Largo is presented with new subdivision of the Q5. (1) In the first phase, the Q1 and Q2 (perhaps deposited during oxygen-isotope stage 11) deep-water quartz-rich environment evolved into a shallow carbonate phase, (2) Subsequently, a Q3 (presumably corresponding to oxygen-isotope stage 9) flourishing reef and productive high-platform sediment phase developed. (3) Finally, a Q4 and Q5 (corresponding to oxygen-isotope stages 7 and 5) stabilization phase occurred with reefs and leeward productive lagoons, followed by lower sea levels presenting a sequence of younger (isotope substages 5c, 5a) shelf-margin wedges, sediment veneers and outlier reefs. The Key largo Limestone provides an accessible model of a carbonate shelf edge with fluctuating water depth, bordering a deep seaward basin for a period of at least 300 ka. During this time, at least four onlaps/offlaps, often separated by periods of karst development with associated diagenetic alterations, took place. The story presented by this limestone not only allows a better understanding of the history of south Florida but also aids in the interpretation of similar persistent shelf-edge sites bordering deep basins in other areas.  相似文献   

15.
A free water surface wetland was built in 2002 to treat wastewater from a tool factory containing metals (Cr, Ni, Zn and Fe), nutrients and organic matter. Until 2006, the last reported period, the wetland retained metals and stored them primarily in the bottom sediment and in the biomass of macrophytes secondarily. The aim of this work was to study metal retention and distribution in the sediment of a constructed wetland for industrial wastewater treatment. Total concentrations and fractions (exchangeable, carbonate-bound, Fe-Mn oxides-bound, organic matter-bound and residual) of metals in sediment were analyzed in this treatment wetland, in order to estimate the fate of metals over time. Metal concentrations were significantly higher in the inlet than in the outlet sediment; concentrations in the latter remained without significant differences throughout the testing period. Metal concentrations and redox potential decreased with depth within the sediment. The lowest metal concentrations and pH and the highest redox values were attained in spring, in agreement with the period of maximum macrophyte growth. Ni and Zn were mainly stored associated with the carbonate fraction; Cr was mainly associated with the Fe-Mn oxides fraction, while Fe was mainly associated with the residual fraction, probably as pyrite. The incoming wastewater composition containing high pH, carbonate, calcium and Fe concentrations favored the observed association in the surface sediment. It would be expected that sediment will continue retaining metals in fractions that will not release them into the water while the chemical and environmental conditions remain unchanged.  相似文献   

16.
Summary An integrated computerized control system, consisting of temperature and moisture sensors, a variable relative humidity air stream and water sprayers was used to control temperature and moisture in the solid substrate fermentation of extruded corn withRhizopus oligosporus in a 15 l rotary drum fermenter. Dry air was blown through the substrate to force evaporative cooling, balanced by spraying of cold water to maintain constant moisture.  相似文献   

17.
The 87Sr/86Sr isotope ratio has been widely used as a physical tool to date and correlate carbonate successions due to the long Sr residence time in comparison with the ocean mixing time. If this method works on oceanic successions, marginal basins may show different Sr isotope records in comparison with the coeval ocean one due to sea‐level variations, continental run‐off and restricted water exchanges. In this work, we present the 87Sr/86Sr isotope record of the upper Miocene carbonate ramp of the Lithothamnion Limestone (Majella Mountain, central Apennines), as an example of the onset of restricted water exchanges between a marginal basin and the ocean water masses. The overall latemost Tortonian–early Messinian Sr isotope record of the Lithothamnion Limestone fits below the global reference line. This deviation has been interpreted as due to the strong control that freshwater input and enhanced continental run‐off, linked to the migration of the Apennine accretionary wedge and foredeep system, have had on the central Adriatic water chemistry. These results imply that an accurate oceanographic and geodynamic framework along with diagenetic overprint investigation has to be taken into consideration prior to apply SIS on carbonate successions on marginal basins, even when facies analyses indicate fully marine conditions. This seems to be the case for the upper Miocene Central Mediterranean carbonate successions, but may have more general validity and be extended to other recent or past marginal basins.  相似文献   

18.
In the present paper, the results of our studies in the type locality of the Dachstein Limestone are summarised in order to contribute to the correct interpretation of the Lofer cycles. In the sections studied on the Dachstein Plateau, the boundaries of the Lofer cycles are usually erosional disconformities showing karstification features. Penetration by karstic solution was not more than a few decimetres, since during the recurrent sea-level drops the platform only slightly emerged above sea level. The reddish or greenish argillaceous carbonate interlayers (facies A) cannot be interpreted as in situ palaeosol horizons. They are tidal flat deposits consisting predominantly of subtidal carbonate mud redeposited by storms that was mixed with reworked airborne fine carbonate particles and argillite and/or reworked lateritic soil, which were accumulated on the subaerially exposed platform. Rip-ups from consolidated sediment, blackened intraclasts and skeletons of tidal flat biota may have also contributed to the sediment of facies A. Erosional boundaries of most of the investigated cycles, and definite features of karstic solution beneath the disconformities, suggest periodical drops of sea level followed by a renewed transgression. This appears to confirm the allocyclic model for the explanation of the origin of the Lofer cycles.  相似文献   

19.
20.
Thomas Olszewski 《Facies》1996,35(1):81-103
Summary The Iola Limestone is the open-marine, carbonate portion of a Midcontinent cyclothem. It represents the transgressive and highstand systems tracts of a stratigraphic sequence. The sequence begins with a type 1 sequence boundary at the base of the Chanute Shale, which underlies the Iola. This surface can be recognized by the presence of a paleosol and as much as 15 m of incision. Part of the Chanute is probably an estuarine valley-fill package and represents the lowstand systems tract. The lowest member of the Iola Limestone is the Paola Limestone Member. Its base is sharp and locally has a thin shell lag. This contact is the transgressive surface and represents the onset of open-marine, clear-water carbonate sedimentation. It is a ravinement surface cut by a winnowing environment that appears as a ‘kink’ in the base-level surface. Landward of this ‘kink’, sediment accumulated to a subaerial base-level, but seaward of it sediment did not accumulate above a subtidal threshold probably controlled by wave base. Facies formed during regression also show the influence of a ‘kink’ in base-level. The Paola itself is the lower part of the transgressive facies tract. Overlying the Paola is the Muncie Creck Shale Member; its lower part is black and fissile, contains phosphate nodules, no unequivocally benthic fossils, and no discernible trace fossils. However, this facies is not present everywhere; in much of southeastern Kansas and just north of Kansas City, Missouri, it has been removed by submarine erosion. The only clues that this facies was ever deposited are reworked diagenetic phosphate nodules that occur as a lag on a hardground on top of the Paola. Where black shale and the immediately overlying, relatively unfossiliferous gray shale have been preserved, they are overlain by a shelly lag that incorporates bored and encrusted micritic cobbles-strong evidence of reworking. This erosional surface is interpreted as the maximum flooding surface. Such an interpretation suggests that the black shale formed during sea-level rise and coastal transgression rather than at sea-level highstand. This is further supported by geochemical properties of Midcontinent black shales. Overlying the maximum flooding surface are a thin gray shale (within the Muncie Creek) and the Raytown Lime-stone Member. In southern Kansas, the limestone contains an extensive phylloid-algal mound. In the subsurface, the elongate Raytown mound is perpendicular to the outcrop belt; it directly overlies a Precambrian structural element called the Bourbon arch, suggesting subtle tectonic control. In northern Missouri and in Nebraska, the upper Raytown contains carbonate tidal-flat deposits. The existence of these two facies suggests that the Raytown was deposited while base-level was stable rather than during base-level drop. The aggradational algal mound built into a positive sea-floor feature and did not shift position through the duration of the cycle. Progradational carbonate tidal flats had the chance to develop in the northern part of the field area; if base-level had been dropping, rapid regression would likely not have permitted accumulation of this facies at the top of the limestone. Coarse-grained deposits, an oncolite in southern Kansas and bioclastic packstones and grainstones in northern Kansas, indicate that the mound aggraded up to a subtidal base-level, presumably controlled by wave base. The carbonate tidal flats, on the other hand, filled accommodation space up to a subaerial base-level as they prograded out over this surface. There must have been two base-levels—one subtidal and the other subaerial—connected by the previously mentioned base-level ‘kink’ at the coastline. The Lane Shale, typically gray-green and silty, overlies the Iola. In a core from northern Missouri, the Lane Shale directly overlying the Raytown contains clay slickensides and a breccia of ‘fitted’ carbonate clasts, indicating subaerial exposure and qualifying the base of the Lane Shale as the top boundary of the Iola sequence. In northwestern Missouri, the Iola changes from a relatively clay-free limestone to mostly dark-gray, calcareous mudrocks with thin shell stringers. This represents a part of the basin dominated by clastic input. Stratigraphic interpretation implies that the Muncie Creek black shale formed during accommodation space increase and shoreline transgression. This is consistent with recent geochemical studies of Midcontinent black shales. This lithology formed as inland peat swamps underwent ravinement and organic matter was flushed onto the shelf. An influx of nutrients and plant material made available by sea-level rise and transgression while sediment was trapped in nearshore accommodation space was the primary cause of sediment starvation and anoxia in the basin.  相似文献   

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