PHYSICO‐GEOCHEMICAL AND MINERAL COMPOSITION OF NEEM TREE SOILS AND RELATION TO ORGANIC PROPERTIES          下载免费PDF全文

WILLIAM C. MAHANEY  JOAN VOROS  RAMANATHAN KRISHNAMANI  RONALD G.V. HANCOCK  SUSAN AUFREITER  MICHAEL W. MILNER  CHRISTOPHER C.R. ALLEN 《Geografiska Annaler: Series A, Physical Geography》2016,98(2):143-154

The Neem tree, the oil of which has a long history of pesticide, fertilizer and medicinal use in India, has been studied extensively for its organic compounds. Here we present a physical, mineralogical and geochemical database resulting from the analyses of two Neem soil profiles (epipedons) in India. Neem tree derivatives are used in the manufacture of a variety of products, from anti‐bacterial drugs and insecticides to fertilizers and animal feeds. A preliminary geochemical and mineralogical analysis of Neem soils is made to explore the potential for chemical links between Neem tree derivatives and soils. Physical soil characteristics, including colour, texture and clay mineralogy, suggest the two pedons formed under different hydrological regimes, and hence, are products of different leaching environments, one well‐drained site, the other poorly drained. Geochemically, the two Neem soils exhibit similarities, with elevated concentrations of Th and rare earth elements. These elements are of interest because of their association with phosphates, especially monazite and apatite, and the potential link to fertilizer derivatives. Higher concentrations of trace elements in the soils may be linked to nutritional derivatives and to cell growth in the Neem tree.  相似文献   

Anatomy of a laterally migrating tidal bar in front of a delta system: Esdolomada Member,Roda Formation,Tremp‐Graus Basin,Spain     

MARIANA I. OLARIU  CORNEL OLARIU  RONALD J. STEEL  ROBERT W. DALRYMPLE  ALLARD W. MARTINIUS 《Sedimentology》2012,59(2):356-378

The first sandstone unit of the Esdolomada Member of the Roda Formation (hereafter referred to as ‘Esdolomada 1’) was formed by a laterally‐migrating, shelf tidal bar. This interpretation is based on detailed mapping of the bedding surfaces on the digital terrain model of the outcrop built from light detection and ranging data and outcrop photomosaics combined with vertical measured sections. The Esdolomada 1 sandbody migrated laterally (i.e. transverse to the tidal currents) towards the south‐west along slightly inclined (1.6° to 4.6°) master bedding surfaces. The locally dominant tidal current flowed to the north‐west. This current direction is indicated by the presence of stacked sets of high‐angle (average 21°) cross‐stratification formed by dunes that migrated in this direction, apparently in an approximately coast‐parallel direction. The tidal bar contains sets and cosets of medium‐grained cross‐stratified sandstone that stack to reach a thickness of about 5·5 m. Individual cross‐bed sets average about 50 cm thick (with a range of 10 to 70 cm) and have lengths of ca 130 to 250 m in a direction perpendicular to the palaeocurrent. Set thickness decreases in the direction of migration, towards the south‐west, and the degree of bioturbation increases, so that the cross‐bedded sandstones gradually change into highly bioturbated finer‐grained and thinner‐bedded sandstones lacking any cross‐stratification. The rate of thinning of individual dune sets as they are traced down any obliquely‐accreting master surface is some 40 cm per 100 m (0·004) for the older, thicker sandstones, whereas the younger, thinner beds thin at a rate of 15 cm over 100 m (0·0015). The tidal bar has a sharp base and top and is encased in finer‐grained bioturbated, marine sandstones. The Esdolomada bar crest was oriented north‐west to south‐east, parallel to the tidal palaeocurrents and to the nearby palaeoshoreline, but built by lateral accretion towards the south‐west. Lateral outbuilding generated a flat‐topped bar with a measured width of about 1700 m, and a preserved height of 5·5 m. The bar, disconnected from a genetically related south‐westward prograding delta some 2 km to the north‐east, developed during the transgressive phase of a sedimentary cycle. The tidal bar was most probably initiated as a delta‐attached bar at the toesets of the delta front and during transgression evolved into a detached tidal bar.  相似文献   

Rhodolith-bearing limestones as transgressive marker beds: fossil and modern examples from North Island, New Zealand   总被引：2，自引：0，他引：2  

RONALD NALIN  CAMPBELL S. NELSON†  DANIELA BASSO‡  FRANCESCO MASSARI 《Sedimentology》2008,55(2):249-274

Rhodoliths are nodular structures composed mainly of the superimposed thalli of calcareous red algae. Because their development is controlled by an array of ecological parameters, rhodoliths are a valuable source of palaeoenvironmental information. However, despite their common use in palaeoecological reconstructions, the stratigraphic significance of rhodolith accumulations seldom has been addressed in detail. In a study of Cenozoic rhodolith‐bearing deposits from the North Island of New Zealand, rhodolithic units, usually of limited lateral extent, typically occur above major unconformities at the base of deepening upwards successions. Two types of transgressive rhodolith‐bearing deposits may be distinguished on the basis of texture and rhodolith internal structure: (i) type A deposits are clast‐supported rhodolithic rudstones containing abundant pebbles and cobbles reworked from the substrate, and are characterized by rhodoliths with a compact concentric to columnar internal structure and a high nucleus to algal cover ratio; (ii) type B deposits are rhodolithic floatstones with a matrix usually consisting of bryozoan fragments, benthic foraminifera and echinoid fragments or terrigenous silty fine sand. The rhodoliths of type B units usually have a loose internal framework with irregular to branched crusts. The two contrasting rhodolith‐bearing units are interpreted as characteristic facies of transgressive systems tract deposits, analogous to shell concentrations formed under conditions of low net sedimentation. Type A deposits are correlated with relatively high‐energy settings and/or narrow submerged palaeotopographic lows, whereas type B deposits are interpreted as forming in lower‐energy settings. The association between transgression and development of rhodolithic facies is confirmed by observations of a modern rhodolith production site at Whangaparaoa Peninsula in North Island, where algal nodules grow above a ravinement surface cut during the Holocene sea‐level rise, and also by a review of published fossil examples, many of which show stratigraphic and compositional attributes analogous to those of the New Zealand occurrences. The review indicates that transgressive rhodolith accumulations develop more commonly in, but are not restricted to, non‐tropical settings. It is suggested that a combination of factors, such as low net sedimentary input, nature of the substrate, sea‐level rise and inherited physiography contribute to determine the relationship between rhodolith‐bearing deposits and transgressive settings.  相似文献   

Low-grade Metamorphism of the Karmutsen Volcanics, Vancouver Island, British Columbia     

STARKEY  ROBERT. J.  JR.; FROST  B. RONALD. 《Journal of Petrology》1990,31(1):167-195

Low-variance assemblages occurring within amygdules of Karmutsenlavas from the Elk Creek and Upper Campbell Lake areas, VancouverIsland, British Columbia, provide important constraints on thepressure and temperature of metamorphism as well as on the compositionof the attendant fluid. The P-T stability of the assemblagesepidote-muscovite-K-feldspar-prehnite and epidote-prehnite-quartz-wairakitecoupled with mean isochores derived from homogenization temperaturesof H₂O inclusions within amygdaloidal quartz indicate that theUpper Campbell Lake area was subjected to metamorphism at 1?5kb (?0?5 kb), 260 ?C (? 15?C) and the Elk Creek area at somewhatlower P or higher T. Isobaric T-a(CO₂) diagrams show that the occurrence of epidote-oligoclase,prehnite-orthoclase-albite, and prehnite-andesine assemblagescollected from the Elk Creek area is consistent with the P-Tconstraints and that these assemblages formed in water-richfluids containing very low concentrations of CO₂. The presenceof Ca-zeolite-epidote assemblages in the Upper Campbell Lakearea is also compatible with P-T estimates. The consistencyof epidote and prehnite rim compositions in low-variance assemblagesand the lack of incompatible phases in these assemblages demonstratethat equilibrium was obtained on limited domains within amygdules. Because epidote and prehnite compositions in low-variance assemblagesare very sensitive to changes in concentration of CO2, low-varianceassemblages involving these phases can serve as monitors offluid composition. It is postulated that low-variance assemblagesin Karmutsen flows originated by reaction of previously formed,high-variance assemblages with infiltrating CO₂-bearing aqueousfluids during a subsequent hydrothermal event. These fluidspreferentially exploited more permeable amygdaloidal portionsof the Karmutsen flows. The low-variance assemblages not onlyrecord the extremely H₂O-rich composition of the permeatingfluid, but also outline the paths the fluid took. ^* Offprint requests to B. R. Frost  相似文献   

Facies architecture and sequentiality of nearshore and 'shelf'sandbodies; Haystack Mountains Formation, Wyoming, USA     

DONATELLA MELLERE  RONALD J. STEEL 《Sedimentology》1995,42(4):551-574

The Haystack Mountains Formation (Campanian, Mesaverde Group, US Western Interior Basin, Wyoming) contains a series of shallow-marine sandbodies, extending tens of kilometres out from a basin margin. The study succession (around 200 m thick) is composed of eight major sandstone tongues (Bolten Ranch, O'Brien Spring, Seminoe 1–2–3–4, Hatfield 1 and 2 members), each partially encased within marine shale intervals. The Formation is ‘sequential’at several scales. At the largest scale, the whole succession presents an aggradational to basinward-stepping stacking pattern of the sandstone tongues. At a lower level, each tongue (member) is characterized internally by two different types of lithosome: the first represents shoreface progradation with hummocky cross-strata passing up to swaley and trough cross-stratified sandstones. This lithosome is erosively truncated at its top in most cases, and has a general sheet-like geometry along strike, whereas down dip it displays a series of sharp-bounded clinothems. The latter sometimes indicate a downward as well as a basinward shift through time, as suggested by the occurrence of coarser and/or shallower facies at a lower level in the shoreface profile. The second type of lithosome is sheet- or wedge-like and sharply overlies the shoreface deposits. The lithosome consists of laterally widespread units of planar tabular to trough cross-bedded medium sandstones passing laterally (in a dip direction) into bioturbated sandstones. The lower part of this lithosome is progradational, becoming retrogradational into the overlying shales. The facies within the cross-bedded lithosome suggest a tidally dominated delta front to estuarine depositional setting. The two types of lithosome are not related genetically. The erosion surface separating the two lithosomes is a sequence boundary separating forced-regressive (relative sea-level fall) shoreface deposits from lowstand to transgressive (early relative sea-level rise), cross-bedded deposits. The uppermost part of the cross-stratified lithosome shows a landward-stepping of component parasequences and is abruptly blanketed by open-marine shales. The most widespread cross-bedded lithosomes are apparently best developed in the lowermost members of the Haystack Mountains Formation, i.e. in the aggradational part of the large-scale progradational succession. In the uppermost, highly progradational sandstone tongues, the shoaling-upward shoreface lithosome dominates, whereas the cross-bedded lithosome occurs in narrow, lensoid belts, or is absent. The middle portion of the succession shows intermediate characteristics. The vertical variation in geometry, thickness and progradational extent of successive cross-bedded lithosomes results from greater confinement of the incised nearshore systems both in space (landward direction) and in time (from the aggradation to the progradation architecture). The latter is a consequence of a decreasing rate of accommodation creation through time.  相似文献   

Determination of Fluorine and Chlorine in Eight USGS Reference Samples Using Automated Photometric Analysis     

RONALD FUGE 《Geostandards and Geoanalytical Research》1981,5(2):183-184

Eight USGS reference samples have been analysed for F and Cl by automated photometric analysis following alkali fusion. The results obtained are, generally, in fairly good agreement with those quoted in the literature.  相似文献   

Microbial alteration of Bahamian deep-sea carbonates   总被引：4，自引：0，他引：4  

MARJORIE L. ZEFF  RONALD D. PERKINS 《Sedimentology》1979,26(2):175-201

An analysis of microborings within sediment and hardground samples collected from the Northwest Providence Channel and the western margin of the Little Bahama Bank was conducted to characterize the endolithic assemblage present, to examine the role of microboring organisms in the alteration of deep-sea carbonates, and to evaluate the palaeoecologic potential of the aphotic microboring assemblage found. Samples examined in this study were collected at depths ranging from 210 to 1450 m. The microboring assemblage was found to contain: (a) filamentous fungal borings of five distinct types, (b) a 1.0 × 2.5 μm vermicular form of fungal or bacterial origin, (c) an 8-12 μm tubular, branching form of probably fungal origin, (d) a subapically branched form considered to be fungal, (e) a spinate form of uncertain affinity and (f) sponge borings. Three of these forms are known only from the deep-marine environment; the remainder are also known from shallow-marine sediments found well within the photic zone. Both carbonate sediments and lithified hardgrounds are highly altered through the activity of endolithic organisms. Infestation of individual skeletal fragments by microborers may be so extensive as to produce heavily bored envelopes resembling those previously reported to occur only under shallow-marine conditions. Although the geological ranges of these microborings remain to be established, the presence of such an aphotic assemblage, coupled with the absence of photosynthetic algal borings, could provide a valuable tool in palaeoecological studies. Other potential applications include the determination of turbidite sediment sources and the establishment of relative water depths for the formation of hardground surfaces.  相似文献   

Fluid Transfer in High-grade Metamorphic Terrains Intruded by Anorogenic Granites: The Thor Range, Antarctica     

BUCHER  KURT; FROST  B. RONALD 《Journal of Petrology》2006,47(3):567-593

A composite intrusive igneous complex in the central mountainrange of Queen Maud Land (Thor Range), Antarctica, displayscharacteristic features of anorogenic granites. A suite of massiveintrusives and various sets of dykes and satellite intrusionsare ferroan, alkalic to alkali–calcic, and weakly peraluminous.An early set of plutons consists of charnockitic alkali-granites;a later group of plutons comprises fayalite Qtz-syenites. Coarsemesoperthite is the dominant mineral in all rocks, quartz isabundant and plagioclase is a minor mineral. Olivine (fayalite)is the characteristic mafic mineral, but subcalcic augite andoccasionally pigeonite or orthopyroxene are present. In mostsamples, amphibole is the dominant mafic mineral and its compositionis close to end-member hastingsite. It contains high concentrationsof F and Cl. Some samples contain igneous fluorite. Thermobarometrysuggests a temperature of 900 ± 25°C and a pressureof 0·4 ± 0·1 GPa for the crystallizationconditions of the pyroxene–olivine assemblages. The solidustemperature of 800–850°C for both suites of plutonicrocks is typical of water-deficient granitic melts. The estimatedlow water activity of 0·3–0·5 at solidusconditions is consistent with the high halogen content of thebulk-rocks and their constituent minerals. In the absence ofan aqueous fluid, the halogens remained in the minerals at thesolidus. Oxygen fugacity stayed below QFM in all igneous rocksabove solidus. This is typical of melts derived from partialmelting of mafic source rocks. The igneous rocks were locallyaffected by at least three distinct episodes of hydration. Asthe melt approached solidus conditions, fayalite and pyroxenewere locally transformed into hastingsite as a result of increasingfugacity of volatile components. Fayalite-free and fayalite-bearingigneous rocks are arranged in banded structures. Subsolidushydration locally modified the igneous rocks and transformedpyroxene- and fayalite-bearing granites into biotite-granitesand hornblende-granites in which all evidence of former high-Thistory was erased. This local hydration of igneous rocks occurredin response to uptake of H₂O that had been given off by gneissicxenoliths as a result of progressing, continuous, dehydrationreactions. The reactions in the gneiss xenoliths were drivenby contact metamorphism. This exchange of H₂O between igneousand metamorphic rocks occurred in a fluid-absent regime at temperaturesof about 750°C. Late reaction veins formed by hydraulicfracturing of the plutonic rocks and indicate the presence ofa low-density fluid phase at amphibolite facies conditions. KEY WORDS: anorogenic granite; fayalite; hastingsite; fluid recycling; Antarctica  相似文献   

SEASONAL VARIABILITY AND SIMULATION OF GROUNDWATER FLOW IN A PRAIRIE WETLAND     

PHILIP J. GERLA  RONALD K. MATHENEY 《水文研究》1996,10(7):903-920

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Quaternary glaciations of the Rongbuk Valley,Tibet     

DANIEL H. MANN  RONALD S. SLETTEN  RICHARD E. REANIER 《第四纪科学杂志》1996,11(4):267-280

Randomisation tests on boulder weathering data distinguish moraines of four different ages in the Rongbuk Valley, all deposited by valley glaciers flowing northward into Tibet from the Himalaya. Lichenometry utilising subgenus Rhizocarpon distinguishes two groups of moraines, those <100 yr old and those older than several thousand years. The degree of soil development has a similar, limited utility in relative-age dating these moraines. The radiocarbon ages of calcium carbonate coatings in the lower horizons of moraine soils provide minimum-limiting ages of 1900 yr BP for the penultimate advance of the Rongbuk glacier (Samdopo moraine) and 9500 yr BP for the Rongbuk moraine, the moraine suggested by previous workers to represent the last glacial maximum. Equilibrium-line depression associated with the Rongbuk moraine probably was slight, <200 m. The small magnitude of this depression relative to glaciers in other mountain ranges could relate to a weakening of the monsoon in full glacial times, recent tectonic uplift, and/or to the insensitivity of these high-altitude glaciers to lowering temperatures in the rain shadow of Mount Everest.  相似文献