Lithostratigraphic signal evaluation of the Miocene Monterey formation, South Elwood field, Santa Barbara-Ventura Basin, California

This dissertation constitutes a multidisciplinary evaluation of Monterey chemostratigraphy, core description, geochronology, and lithostratigraphic evaluation from a structurally uncomplicated, thermally immature, distal slope setting as studied from a remarkably continuous 300 m core from the offshore South Elwood oil field.;An age model for the South Elwood core is constructed from integration of multi-microfossil biostratigraphy and strontium isotope chronostratigraphy. Application and resolution of biostratigraphic efforts proved to be limited due to silica phase diagenesis, a process effectively destroying age-diagnostic diatoms while encasing calcareous microfossils within an undisaggregable matrix of opal-CT or diagenetic quartz. Strontium isotope chronostratigraphy, employing bulk carbonate leaching, proved effective in delineating the Miocene record of seawater ;Quantitative mineralogy analyses of core lithofacies are used to construct an empirical model of basic lithofacies compositional variation. South Elwood lithofacies are principally comprised of four components: detritus, diagenetic silica, calcite, and dolomite. Relative abundances of these components define endmember and intermediate composition lithotypes, the latter introducing subjectivity into visual lithofacies assignment. Comparison of lithofacies assigned by visual core description and quantitative mineralogy demonstrates that the modal lithic component can generally be inferred from visually-assigned lithofacies.;With this empirical observation, a digital filtering process is developed to evaluate the record of hemipelagic-pelagic depositional mode switching in the South Elwood core. Core lithofacies are lumped into pelagic, hemipelagic, or other modes and internormalized cumulative thickness curves compiled. The curves are differentiated and smoothed via filter-length adjustment to derive fractional composition curves at "bedding" scale and lower frequencies. Resultant hemipelagic and pelagic signals are highly anticorrelated, with longer filter-lengths producing highly oscillatory functions. Peaks in hemipelagic deposition show a strong relation to organic carbon-rich core intervals, many of which are phosphatic, above the Rincon-Monterey contact, but are not significantly coupled below this level. Based on the strontium isotope age model, peaks in hemipelagic accumulation appear to closely approximate mid-sequence downlap surfaces signifying depositional periods associated with maximum flooding rates.;Through strontium isotope correlations with the Site 747 stable isotope record, the temporal relationship of South Elwood organic carbon accumulation to the Miocene carbon and oxygen excursions are considered. Initial significant organic carbon accumulation at South Elwood coincides closely with the initial carbon isotopic enrichment shift at Site 747, and carbon isotope maxima identified at Site 747 correspond to the condensed interval at South Elwood. The condensed interval brackets the period of initial oxygen isotopic enrichment at Site 747. The record of volcanism at South Elwood, primarily recorded as thin bentonite layers, wanes exponentially upsection over the depositional time period from 19 to 13 Ma, consistent with timing of initial clockwise tectonic rotation of the western Transverse Ranges block. The base of high frequency volcanism corresponds to the period of initial high organic carbon accumulation at South Elwood. If the South Elwood volcanostratigraphic record constitutes a regional tectonic proxy, the correspondence of initial high frequency volcanism and onset of significant organic carbon accumulation may be tectonically linked. (Abstract shortened by UMI.).