Controls of the chemical composition of particle populations in a macrotidal estuary (Tamar Estuary, U.K.)     

A.W. Morris  A.J. Bale  R.J.M. Howland  D.H. Loring  R.T.T. Rantala 《Continental Shelf Research》1987,7(11-12)

The chemical composition of suspended particulate material (SPM) in the Tamar Estuary and its response to tidal sediment resuspension at the turbidity maximum have been investigated. The results discriminate four regions: (1) the outer estuary where spatial changes in the composition of SPM reflect the dispersal of estuarine particles modified by in situ generation of organic particles, (2) the middle estuary where the composition of SPM is mainly determined by hydrodynamic mixing although there is some evidence of in situ chemical reactivity, (3) the upper estuary where sharply distinct and temporally variable SPM compositions are centred at the turbidity maximum; these are largely the result of particle-selective accumulation, sedimentation and resuspension processes rather than of local particle-water chemical exchanges, and (4) the fluvial estuary where the SPM composition reflects the influx of riverine particles.  相似文献   

Petrology of the Campbell Island Volcanics, Southwest Pacific Ocean     

Paul A. Morris   《Journal of Volcanology and Geothermal Research》1984,21(1-2)

The disposition and petrology of a fractionated alkali olivine basalt—peralkaline rhyolite suite from subantarctic Campbell Island are discussed. These rocks (Campbell Island Volcanics: new name) are flows and high-level intrusions derived from two centres of igneous activity. Their age is Upper Miocene and they evolved over a period of 5 Ma. A gabbro intrusion pre-dates volcanism by 5 Ma. The ages of the flows and high-level intrusions cannot be separated, although the intrusions are chemically distinct as they contain all the intermediate members of the suite (mugearite and benmoreite). Similar La/Ce and Zr/Nb ratios for flows and high-level intrusions suggest a co-magmatic origin. Chemical variations indicate that the suite resulted from low-pressure mafic then felsic-dominated fractional crystallisation, which is substantiated for intermediate members of the suite by least-squares and Rayleigh fractionation modelling. One flow of alkali olivine basalt clearly pre-dates other volcanic rocks, and is thus regarded as being genetically unrelated.Although chemically similar to alkali olivine basalt and hawaiite, variations in the mineral chemistry and modal mineralogy of gabbro indicates a prolonged period of in-situ fractionation and re-equilibration.  相似文献   

Effects of age on the chemical structure of paleosol humic acids and fulvic acids     

Gilberto Calderoni  Morris Schnitzer 《Geochimica et cosmochimica acta》1984,48(10):2045-2051

Humic acids and fulvic acids were extracted from six paleosols in Southern Italy. Humic acids (HAs) constituted between 96.5 and 99.2% of the total extracts; the remaining materials consisted of fulvic acids (FAs). Radiocarbon ages of the HAs ranged from about 6,000 to close to 29,000 years B.P., δ¹³C values averaged $\text{?25.6 ± 0.3‰}$ The HAs were characterized by chemical (elemental and functional group analyses) and spectroscopic (IR, ESR, ¹³CNMR, E₄/E₆ ratios) methods. FAs were characterized by chemical methods, E₄/E₆ ratios and IR spectra.The chemical and spectroscopic analyses showed practically no differences in the chemical structure and composition of the six HAs and FAs, so that age appeared to have little effect on these parameters. The paleosols were found to be closed systems with low polysaccharide and protein contents, thus providing unfavorable substrates for microbial activity. The preservation of the humic materials in the paleosols may have been due to low biological activity and/or to retention by amorphous minerals. The HAs did not appear to be affected by temperatures higher than 170–200°C over the 23,000 year period which we observed.  相似文献   

The abundance of water and rock in Jupiter as derived from interior models     

Morris Podolak 《Icarus》1977,30(1):155-162

Models of Jupiter's interior were computed using a new molecular hydrogen equation of state, and a more precise algorithm for computing gravitational moments. Models with H/H_e ratios of 13.5, 11.25, and 10 were computed, and it was found that the models had rocky cores of 16 to 18 Earth masses and envelopes with 20 to 50 Earth masses of water. Models with temperatures of less than 180°K at 1 bar had water-to-rock ratios which were less than the solar value, thus removing a difficulty of previous computations. Models were also constructed in which rock was put into the envelope in place of water. It was found that, to a good approximation, a given mass of rock will replace an equal mass of water. At present the two cases are indistinguishable.  相似文献   

On inhomogeneous scattering models of Titan's atmosphere     

Morris Podolak  Lawrence P. Giver 《Icarus》1979,37(2):361-376

The spectrum of Titan from 4800 to 11 000 Å has many CH₄ absorption bands which cover a range of intensities of several orders of magnitude. Yet even the strongest of these bands in Titan's spectrum has considerable residual central intensity. Some investigators have concluded that these strong CH₄ bands must be highly saturated, but recent laboratory measurements of the bands made at room temperature show that curve-of-growth saturation is very small. At the presumed low pressures and temperatures in Titan's atmosphere, we show that saturation is very dependent on the band model parameters. However, in either a simple reflecting layer model or in a homogeneous scattering model saturation cannot be the principal cause of the filling in of these strong CH₄ bands if our best estimates of the band model parameters are correct. We find that an inhomogeneous scattering model atmosphere with fine “Axel dust” above most ot the CH₄ gas is needed to fill in the band centers. The calculated spectrum of one particular model of this class is compared to observations of Titan. Our essential conclusion is that Titan does have most of its scattering particles above most of the CH₄ gas which has an abundance of at least 2 km-am. This large abundance of CH₄ is necessary to produce the 6420-Å feature recently discovered in Titan's spectrum.  相似文献   

A Framework for Modeling Uncertainty in Spatial Databases   总被引：1，自引：0，他引：1  

A Morris 《Transactions in GIS》2003,7(1):83-101

Geographic Information Systems and spatial databases are inherently suited for fuzziness, because of the uncertainty inherent in the assimilation, storage, and representation of spatial data. These objects may also have naturally occurring imprecise boundaries. It is difficult to store and represent these objects while continuing to demonstrate the uncertainty inherent in the objects. This paper describes a fuzzy object–oriented framework to model spatial objects with either precise or uncertain boundaries that will also provide for fuzzy querying of these objects. A prototype system, FOOSBALL, which implements this framework is also discussed.  相似文献   

Seafloor spreading in the Weddell Sea from magnetic and gravity data     

L. C. Kovacs  P. Morris  J. Brozena  A. Tikku   《Tectonophysics》2002,347(1-3)

A re-compilation of magnetic data in the Weddell Sea is presented and compared with the gravity field recently derived from retracked satellite altimetry. The previously informally named ‘Anomaly-T,’ an east–west trending linear positive magnetic and gravity anomaly lying at about 69°S, forms the southern boundary of the well-known Weddell Sea gravity herringbone. North of Anomaly-T, three major E–W linear magnetic lows are shown, and identified with anomalies c12r, c21–29(r) and c33r. On the basis of these, and following work by recent investigators, isochrons c13, c18, c20, c21, c30, c33 and c34 are identified and extended into the western Weddell Sea. Similarly, a linear magnetic low lying along the spine of the herringbone is shown and provisionally dated at 93–96 Ma. Anomaly-T is tentatively dated to be M5n, in agreement with recent tectonic models.Although current tectonic models are generally in good agreement to the north of T, to the south interpretations differ. Some plate tectonic models have only proposed essentially north–south spreading in the region, whilst others have suggested that a period of predominantly east–west motion (relative to present Antarctic geographic coordinates) occurred during the mid-Mesozoic spreading between East and West Gondwana. We identify an area immediately to the south of T which appears to be the southerly extent of N–S spreading in the herringbone. Following recent work, the extreme southerly extent of the N–S directed spreading of the herringbone is provisionally dated M9r/M10. In the oldest Weddell Sea, immediately to the north and east of the Antarctic shelf, we see subtle features in both the magnetic and gravity data that are consistent with predominantly N–S spreading in the Weddell Sea during the earliest opening of East and West Gondwana. In between, however, in a small region extending approximately from about 50 km south of T to about 70°S and from approximately 40° to 53°W, the magnetic and gravity data appear to suggest well-correlated linear marine magnetic anomalies (possible isochrons) perpendicular to T, bounded and offset by less well-defined steps and linear lows in the gravity (possible fracture zones). These magnetic and gravity data southwest of T suggest that the crust here may record an E–W spreading episode between the two-plate system of East and West Gondwana prior to the initiation of the three-plate spreading system of South America, Africa and Antarctica. The E–W spreading record to the east of about 35°W would then appear to have been cut off at about M10 time during the establishment of N–S three-plate spreading along the South American–Antarctic Ridge and then subducted under the Scotia Ridge.  相似文献   

Multibeam bathymetry and the depositional environments of Kongsfjorden and Krossfjorden, western Spitsbergen, Svalbard     

John A. Howe  Steven G. Moreton  Clara Morri  Peter Morris 《Polar research》2003,22(2):301-316

Kongsfjorden and Krossfjorden are two ice-proximal fjords on the western coast of Spitsbergen which have been surveyed using multibeam bathymetry, sub-bottom profiling and gravity coring. Central and outer Kongsfjorden is dominated by a 30 km² outcrop of bedrock, with a thin (<10m) sediment cover. The bedrock displays a relict sub-glacial, ice-scoured topography produced during the glacial re-advances of the Weichselian (20 Ky BP) and again during the last major Holocene re-advance of the Little Ice Age (550-200 yrs BP). Drumlins and glacial flutes are common across the floor of Kongsfjorden, with lengths of 1.5-2.5 km and widths of <100 m, rising up to 10 m in water depths of <100 m. This topography is smoothed by bottom currents from the wind-driven forcing of surface waters. The flow is counter-clockwise, matching boundary layer movement under the influence of Coriolis force. Both fjords are characterized by a variable acoustic character, based on sub-bottom profile data. The deepest basins are dominated by parallel, well-laminated reflectors and an irregular-transparent acoustic character indicating the presence of Holocene-age fine-grained sediments up to 30 m thick. A parallel, irregular-transparent acoustic character with waveform morphology in inner Kongsfjorden is interpreted as moraines, originating from the 1948 and 1869 surges of Kronebreen glacier. Mass-flows are common on the flanks of topographic highs as acoustically chaotic-transparent lensoid and wedge-shaped reflectors. The sediments of outer and central Kongsfjorden are characterized by bioturbated, gas-rich homogeneous muds interpreted as being the result of the settling of fine-grained sediment and particulate suspensions.  相似文献   

Design of Dry Barriers for Containment of Contaminants in Unsaturated Soils     

Carl E. Morris  Bruce M. Thomson  John C. Stormont 《Ground Water Monitoring & Remediation》1999,19(3):145-156

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Basement geology beneath the northeast Thelon Basin,Nunavut: insights from integrating new gravity,magnetic and geological data   总被引：1，自引：0，他引：1       下载免费PDF全文

V. Tschirhart  C.W. Jefferson  W.A. Morris 《Geophysical Prospecting》2017,65(2):617-636

Current models for unconformity‐associated uranium deposits predict fluid flow and ore deposition along reactivated faults in >1.76 Ga basement beneath Mesoproterozoic siliciclastic basins. In frontier regions such as the Thelon Basin in the Kivalliq region of Nunavut, little is known about the sub‐basin distribution of units and structures, making exploration targeting very tenuous. We constructed a geological map of the basement beneath the unconformity by extrapolating exposed features into the subsurface. The new map is constrained by detailed geological, geophysical, and rock property observations of outcrops adjacent to the basin and by aeromagnetic and gravity data over the geophysically transparent sedimentary basin. From rock property measurements, it is clear that the diverse magnetic and density characteristics of major rock packages provide quantitative three‐dimensional constraints. Gravity profiles forward modelled in four cross sections define broad synforms of the Amer Belt and Archean volcanic rocks that are consistent with the structural style outside the basin. Major lithotectonic entities beneath the unconformity include: supracrustal rocks of the Archean Woodburn Lake group and Marjorie Hills meta sedimentary gneiss and associated mixed granitoid and amphibolitic gneiss; the Amer Mylonite Zone and inferred mafic intrusions oriented parallel and sub‐parallel; other igneous intrusions of 2.6 Ga, 1.83 Ga, and 1.75 Ga vintage; and the <2.3 Ga to >1.84 Ga Amer Group. Four main brittle regional fault arrays (040°–060°, 075°–90°, 120°, and 150°) controlled development and preservation of the basin. The reactivated intersections of such faults along fertile basement units such as the Rumble assemblage, Marjorie Hills assemblage, Nueltin igneous rocks, and Pitz formation are the best targets for uranium exploration.  相似文献