Major and trace element analyses were made on biogenic carbonate, silica, and fish debris and on authigenic philhipsite, micronodules, and yellow and brown aggregates recovered from Bauer and Roggeveen Basin metalliferous sediments. Phase components and the bulk samples were analyzed by INAA and MS methods. Leachates and residues from ammonium oxalate and mild HC1 leaches of bulk and fine sediment fractions were also analyzed. The mild acid leach removed fish debris and carbonate, and the oxalate leach dissolved the micronodule phase. Sediments of the Bauer and Roggeveen Basins differ in bulk composition, yet respond to various chemical treatments in similar manner. I interpret this as indicative of a close similarity in the mineralogy of these two areas. An iron-rich smectite, manganese micronodules, and fish debris dominate the sediment compositions of both basins. The smectite phase concentrates Fe, Si, and Al. Manganese, Co, Ni, Ce, and W are concentrated in the micronodule phase and Ca, Sc, and the lanthanides predominantly in the fish debris component. The trace elements Cu, Zn, As, and Sb are distributed in a complex manner among the three principal phases. Barium, and some Al and Fe, may be present in small quantities of barite, feldspars, and goethite, respectively. Silica, carbonate, and phillipsite phases exist in. such low concentrations that they do not contribute significantly to the bulk composition of the sediments. The response of the various size fractions leached indicates a uniformity of distribution of sediment components from the coarse to the fine fractions. / Graduation date: 1978

Cores taken from the ridge areas of the Gorda-Juan de Fuca plate have a sedimentation rate that is appropriate for the study of late Quaternary stratigraphy. An analysis of the clay and silt mineralogy of the cores using X-ray diffraction methods and by noting changes in the foraminiferan-radiolarian abundances in the cores were utilized in developing a stratigraphic sequence. The clay fractions of these sediments consists of chlorite, illite and smectite. Cores taken from bathymetric highs contain, on the average, less smectite than do the turbidites from the adjacent lowlands. The low smectite content suggests eolian enrichment of these sediments since dusts collected from the nearby continent also have low smectite concentrations. Changes in the relative abundances of radiolaria and foraminifera are used to put biostratigraphic constraints on the correlation of mineralogical datums. Two changes in the foraminiferan-radiolarian ratios, marked by sharp increases in the abundance of radiolaria, occurred at 12,500 years B.P. and 83,000 years B.P. as dated by carbon-14 and sedimentation rate extrapolations, respectively. Such faunal changes serve as an independent check of correlations of the mineralogical datums. In the 2 to 20 micron, silt fraction, quartz, chlorite, mica and feldspar are the predominant minerals. Intervals in which the relative abundance of quartz changes can be dated by carbon-l4 and sedimentation rates, and related to late Quaternary climatic events. The quartz-rich zones are synchronous with periods of high insolation, high stands of sea-level, and to a lesser degree with the catastrophic floods of the Columbia River. The correlation with high solar radiation reflects quartz enrichment of the sediment due to an increased eolian contribution. The coincident high sea level stands effectively decreased the sedimentation rate of quartz-poor continental detritus that otherwise dilutes the eolian component. The periodic floods of the Columbia River, caused by the failure of ice dams, swept quartz-rich loess from eastern Washington down the river and injected into the marine environment. Such sediment also increased the quartz abundance in the quartz-rich zones on the ridges. Thus, the late Quaternary stratigraphy of the cores can be related to global late Quaternary climatic variations as well as to events recorded on the adjacent continents. The structural development of the Gorda-Juan de Fuca plate over the last 10 million years can be explained by north-south shortening coupled with the normal tectonism associated with a spreading sea floor. This hypothesis for the development of the plate is based on the presently known magnetic anomaly pattern. A series of reconstructions of this pattern back through the past 10 million years shows that both the Gorda and Juan de Fuca portions of the plate have grown steadily smaller. The incorporation of sequentially shorter Gorda ridge anomalies into the Pacific plate appears to have led to the northwest-southeast orientation of the Blanco Fracture Zone, with consequent changes in the direction of spreading of the Juan de Fuca Ridge. On the Juan de Fuca portion of the plate, the shortening was accomplished by shear faulting in Cascadia Basin. Furthermore, this faulting resulted in the rapid subduction of this portion of the plate, which, in turn, produced a disconformity in the sediments of Cascadia Basin. The reconstruction strengthens the notion that right lateral strike slip motion between the Pacific and Gorda-Juan de Fuca plate does, indeed, exist. / Graduation date: 1974

In order to determine whether the sediments found on the landward wall of the Peru Trench are accreted Nazca Plate sediments, the clay mineralogy and organic carbon contents of 52 surface samples were submitted to factor analysis. Q-mode factor analysis resolved the data from the Nazca Plate and Peru continental margin into three factors. The most important factor (oceanic assemblage) is strongly associated with Nazca Plate sediments and is comprised of smectite and aeolian illite. In contrast, upper continental margin sediments are dominated by either of the two continental factors (A or B). The principal difference between the continental factors is that mixed-layer smectite-chlorite clays are characteristic only of continental assemblage A. Lower continental margin sediments are characterized by either an oceanic or continental factor dominance. The boundary between sediments dominated by the oceanic factor and those dominated by the continental factor was as much as 100 km to the west of its present position earlier in the Quaternary. The seaward shift in the boundary is attributed to westward shoreline displacement in response to glacially-induced sea level changes, increased erosion rates on land during more humid times, and deposition of continental factor dominated sediments seaward of the present Peru Trench axis. Quaternary sediments from 27 cores reveal minor fluctuations with time in factor loadings in Nazca Plate and upper continental margin cores and significant variations in some areas near the trench axis and on the middle to lower continental slope. Displacement of oceanic sediments into areas with continental sediments is determined with respect to the factor dominance boundary. Using this method, continental accretion is indicated for five cores, located up to 3000 m above the trench floor. One core on the middle continental slope off Lima, Peru, contains diatom-rich Quaternary dolomite that probably originated as calcareous sediment on the Nazca Ridge. If this is true, left-lateral strike-slip motion of the Nazca Ridge along the Peru Trench axis is indicated. The bulk of the 28 cores recovered from the acoustically complex landward wall of the Peru Trench contain sand-silt turbidites of continental origin. Even though there is a distinct overprint of terrigenous sedimentation, accreted oceanic sediments can be recovered in a tectonically active convergent plate boundary. / Graduation date: 1974

Major (Fe, Mn, Al) and minor (Cr, Mo, Pb, Zn, Cd) element analyses of metalliferous sediments in cores from the East Pacific Rise and Bauer Deep indicate that the Bauer Deep sediments are similar in chemistry and origin to metalliferous sediments of the East Pacific Rises. Fe, Pb, and Zn are strongly associated in both cores and are probably related to the hydrothermal processes which are postulated to occur on the East Pacific Rise. Incomplete Cd data suggest that Cd may also be released during hydrothermal leaching of basalt Mn may originate by precipitation from hydrothermal solutions or by normal authigenic precipitation from sea water. The similar accumulation rates of Mo in both cores, and poor correlation of Mo with Fe imply that Mo is being extracted from sea water. The low abundances of Cr and Al in metalliferous sediments suggest that detritus is a minor component of the sediments. Poorly crystalline smectites constitute a major mineralogical phase of metalliferous sediments. Chemical and mineralogical studies indicate that the smectite is an iron-rich montmorillonite, similar in composition to the bulk sediment. Information on sedimentation rates in the two cores indicate that most elements are accumulating faster on the East Pacific Rise than in the Bauer Deep. Accumulation rates of metals in the Bauer Deep have decreased up to the present and are currently similar to those for normal pelagic sediments. It is inferred that the sedimentation rates in the Bauer Deep are influenced by the proximity of the East Pacific Rise, It appears that sediments in the Bauer Deep are largely the product of hydrothermal processes on the East Pacific Rise, and that the precipitates are transported in suspension to the Bauer Deep. Authigenic precipitation of elements from sea water also occurs, having a stronger influence on the sediments as the precipitation of rise-crest material decreases away from the ridge. / Graduation date: 1974

Examination of polished sections of manganese micronodules from metalliferous sediments from the Bauer Deep reveals sequences of ferromanganese deposition which are consistent for micronodules from a single sediment sample and imply a common depositional history for members of such assemblages. The relatively simple 'stratigraphy' of manganese micronodules, as compared to macronodules, makes stratigraphic correlation of depositional histories easier and more conclusive for micronodules than macronodules. Quantitative microprobe analysis and X-ray mircodiffraction patterns indicate that the major authigenic silicate component of metalliferous sediment is an iron- and magnesium-rich, low-aluminum nontronite. Microprobe and X-ray microdiffraction analyses of manganese micronodules establish todorokite as the predominant crystalline component. Comparison of the distributions of lanthanum, cerium, and samarium in micronodules and phosphatic fish debris indicates that bulk sediment REE distribution is determined by the relative abundances of cerium-enriched micronodules and cerium-depleted biogenic phosphate. / Graduation date: 1974

Photocopy of typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1978. / Bibliography: leaves 219-235. / Microfiche. / xiii, 311 leaves ill., maps

Photocopy of typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1979. / Bibliography: leaves 186-200. / Microfiche. / xi, 256 leaves ill., map 29 cm

Typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1974. / Bibliography: leaves 155-164. / viii, 164 leaves ill., map

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Science, 1980. / Microfiche copy available in Archives and Science. / Bibliography: leaves 79-80. / by Andrew G. Hudson. / M.S.