Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Science, 1982. / Microfiche copy available in Archives and Science / Vita. / Bibliography: leaves 110-111. / by Gerald Alan LaTorraca. / Ph.D.

Thesis. 1978. Ph.D.--Massachusetts Institute of Technology. Dept. of Earth and Planetary Science. / Microfiche copy available in Archives and Science. / Vita. / Bibliography: leaves 200-203. / Ph.D.

Including porosity introduces absorption into the previously developed scattering analysis for elastic spheres. Acoustic propagation in porous media has two distinct compressional modes, one in which the fluid and the structure move in phase with each other and the other in which they move in opposite phase. Expressions for the complex wavenumbers of both waves are derived, using the parameters for manganese nodules. A modal analysis with a pressure boundary condition indicates that the first kind of compressional wave is lightly attenuated and carries most of the energy of the coupled system. The second compressional wave is highly attenuated and effectively loses all of its energy in the first centimeter of the nodule. This second wave is very important for consideration of nodule-scale dimensions since it represents the dominant loss mechanism. A method was developed to form a single effective compressional wave attenuation for both compressional waves by employing a pressure and velocity boundary condition at the surface of the nodule and using a spatially integrated intensity match. An effective wave attenuation is generated for the compressional wave in the non-porous elastic model which accounts for porous attenuation and which is based on a parameter defined as travel distance L. If L is assumed to be proportional to nodule radius, the attenuation is approximated as constant for the frequency range of interest and is independent of nodule radius. An effective attenuation is predicted. The shear attenuation is found to exhibit a frequency squared form dependence for manganese nodules. However, shear attenuation is very small for ideal nodules and is negligible compared to the compressional loss. The elastic model of the nodule was numerically altered to accommodate complex wavenumbers in shear and compression. Four distinct regions of attenuation are observed in individual reflectivity, R_θ, versus ka plots and discussed. The importance of including attenuation is readily apparent from observing the transformation of the elastic non-porous results. Scattering experiments were performed on manganese nodules and experimental individual reflectivity versus ka plots were generated. Good agreement is found for the spherical Atlantic nodules using values in the third region of attenuation. From these experiments, an estimation of attenuation is made and compared with the theoretical prediction. The influence of attenuation on individual scattering and multiple scattering is investigated. Attenuation tends to shift the major bottom reflectivity, C_R, peak toward lower ka values. This affects the prediction of the acoustic response of manganese nodule deposits. / Master of Science

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The submerged paleodrainage system of the early Balize delta complex that extended onto the inner continental shelf at 1500 YBP has not been completely studied in great detail. This study interprets the environmental deltaic facies of the Balize Delta, in the Sandy Point region offshore the southeastern Louisiana coast from 120 km of seismic data and 48 vibracores. The stratigraphic and environmental units established in this study provide a geological framework for this area. Overlying Holocene deposits interpreted to be muds of prodelta and lower delta front origin were interpreted as having been deposited from the retreating delta sit atop a transgressive surface, indicated by the toplapping seismic reflectors, the ravinement surface. The deltaic facies below the ravinement surface are of regressive origin an inner shelf delta with widespread delta front sheet sands from a dense group of many distributaries. This research provides a concise methodology adapted from multiple studies for modeling deltaic facies of offshore sand resource targets. / by Zachary Samuel Mester. / Thesis (M.S.)--Florida Atlantic University, 2011. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2011. Mode of access: World Wide Web.

[Tuncated abstract] Soil is a relatively low cost and robust geochemical sampling medium and is an essential part of most mineral exploration programs. In areas of covered terrain, however, soils are less reliable as a sampling medium because they do not always develop the geochemical signature of the buried mineralisation; possibly a result of limited upward transport of ore related elements into the surficial overburden. As economic demands on the resources industry grow, mineral exploration continues to expand further into areas of covered terrain where the rewards of finding a new deposit relative to the risks of finding it may be comparatively low. Thus, improving the costeffectiveness of a geochemical exploration program requires a sound understanding of the mechanisms by which soil geochemical anomalies form in transported overburden. This thesis examines the deep biotic uplift of ore related elements by deep rooting vegetation as a mechanism for the development of soil geochemical anomalies within transported overburdens, in semi-arid and arid regions. '...' Vegetation and soils were analysed at two Au prospects in Western Australia: Berkley, Coolgardie and Torquata, 210 km south-east of Kambalda, in semi-arid Western Australia to complement both the mass balance and the differential modelling. At Berkley, both the vegetation and soils located directly over the mineralisation showed high concentrations of Au. There may be indirect evidence for the operation of the deep plant uptake flux taking effect from the field evidence at Berkley. Firstly, anomalous concentrations of Au were found in the surface soils, with no detectable Au in the transported overburden. Secondly, the trace element concentrations in vegetation showed correlation to the buried lithology, which to our knowledge has not been reported elsewhere. The results from the samples at Torquata, in contrast, were less conclusive because the Au is almost exclusively associated with a surficial calcrete horizon (at <5 m soil depth). Strong correlations of Ca and Au in leaf samples however, suggest that the vegetation may be involved in the formation of calcrete and the subsequent association of Au with the calcrete. Among the vegetation components, the litter and leaf samples gave the greatest anomaly contrast at both prospects. Finally, three main drivers for the deep biotic uplift of elements were identified based on the results from the mechanistic numerical modelling exercise: i) the deep uptake flux; ii) the maximum plant concentration and; iii) the erosional flux. The relative sizes of these three factors control the rates of formation and decay, and trace element concentrations, of the soil anomaly. The main implication for the use of soils as exploration media in covered terranes is that soil geochemical anomalies may only be transient geological features, forming and dispersing as a result of the relative sizes of the accumulative and loss fluxes. The thesis culminates in the development of the first quantitative, mechanistic model of trace element accumulation in soils by deep biotic uplift.

No description available.

Text in Afrikaans / Prospektering is een van die eerste en belangrikste stappe in die mineraalontginningsproses en dit word ondersoek teen die agtergrond van die Mineraalwet 50 van 1991, wat die belangrikste "mynwette" herroep en die Suid-Afrikaanse mineraal- en mynreg in vele opsigte op 'n heel nuwe grondslag geplaas het. Die hoofdoel met hierdie proefskrif is om prospekteerregte te sistematiseer en te bepaal of dit beperkte saaklike regte daarstel. Ten aanvang word bepaal welke aktiwiteite prospektering daarstel en welke stowwe regtens as minerale kwalifiseer. Daar word gekyk na die regte waarvan prospekteerregte dee! vorm of waaruit dit afgelei word, naamlik eiendomsreg en mineraalregte. Die afskeiding van minerale van grond, die afskeiding van mineraalregte van grondeiendomsreg en die afskeiding van prospekteerregte van mineraalregte en grondeiendomsreg, asook die inhoud van en beperkings op die uitoefening van prospekteer- en mineraalregte, word ook ondersoek. Daar word veral aangetoon dat mineraalregte nie so wyd is as wat algemeen aanvaar word nie en dat dit 6f by die af skeiding van die roerende minerale tot niet gaan of uitgeput raak 6f in eiendomsreg daarop oorgaan. Prospekteerregte word meestal verleen by wyse van prospekteerkontrakte, waarvan daar verskillende verskyningsvorme bestaan en waarvan die een wat in die Registrasie van Aktes Wet 47 van 1937 omskryf word, as uitgangspunt geneem word. Aangesien die reg om te myn ook die reg om te prospekteer insluit, word die verlening van mynregte en antler verkrygings van prospekteerregte ook behandel. Alvorens gemeneregtelike prospekteerregte egter uitgeoefen mag word, meet magtiging daarvoor by die staat verkry word. Die verlening van statutere prospekteer- en mynmagtigings het by die inwerkingtreding van die Mineraalwet 50 van 1991 grondige veranderings ondergaan wat tesame met die relevante oorgangsbepalings ondersoek word ten einde die uitwerking van die wet op prospekteerregte te bepaal. Die vereistes vir en die regsaard van die verskillende regte word ondersoek ten einde 'n oorsig van prospekteerregte daar te stel en dit vlugtig met veral Australiese reg te vergelyk. Daar word tot die gevolgtrekking geraak dat blote prospekteerregte nie beperkte saaklike regte daarstel nie. / Prospecting is one of the first and most important steps in the minerals exploitation process and is examined against the background of the Minerals Act so of 1991, which repealed the most important "mining" legislation and in many ways placed the South African mining and minerals law on a completely new basis. The main purpose of this thesis is to systematise prospecting rights and to establish whether they constitute limited real rights. It is at the outset determined which activities constitute prospecting and which materials qualify in law as minerals. The rights from which prospecting rights are derived or of which they form part, namely ownership and mineral rights, are considered. The severing of minerals from land, the severing of mineral rights from landownership and the severing of prospecting rights from mineral rights and landownership, as well as the contents of and limitations on the exercising of prospecting and mineral rights, are also examined. It is in particular shown that mineral rights are not as comprehensive as is generally accepted and that they either terminate or are exhausted upon severance of the movable minerals from the land or are converted into ownership thereof. Prospecting rights are mostly granted by way of prospecting contracts, of which different varieties exist and of which the one defined in the Deeds Registries Act 47 of 1937 is taken as the starting point. Since the right to mine includes the right to prospect, mining rights and other acquisitions of prospecting rights are also considered. Before common law prospecting rights may be exercised, however, authority to do so must be obtained from the state. Upon the commencement of the Minerals Act 50 of 1991, the granting of statutory prospecting and mining authorisations underwent fundamental changes, which are examined with the relevant transitional provisions to determine the effect of the act. The requirements for and the juridical nature of the various rights are considered in order to establish an overview of prospecting rights and briefly to compare them mainly with Australian law. The conclusion is reached that mere prospecting rights do not constitute limited real rights. / Jurisprudence / LL. D.