Thesis (M. Sc.), Memorial University of Newfoundland, 1998. / Bibliography: leaves 63-73. Also available online.

The Altona Formation represents the oldest Cambrian sedimentary unit in northern New York, recording cyclic deposition in shallow marine and fluvial environments under both fair-weather and storm conditions. Five outcrops and one well log were measured and described at the centimeter scale and the top and bottom contacts of the Altona were identified. Based on the recognition of sedimentary structures such as hummocky cross stratification, oscillatory ripples, graded bedding, trough and tabular cross stratification, and bioturbation, as well as subtle lithologic changes, six lithofacies representing non-marine, middle to upper shoreface, offshore, and carbonate ramp environments were identified. The top contact with the overlying Ausable Formation is characterized by inter-tonguing marine to non-marine siltstones and cross stratified medium sandstones. The lowermost Altona is found to lie only one meter above Precambrian basement and is interpreted to be the only non-marine facies in this unit. Throughout the 84-meter thick section, stratigraphy records a transition from upper/middle shoreface to carbonate ramp deposition and offshore muds before cycling between upper shoreface, carbonate ramp and non-marine deposits. Based on parasequence architecture, this section of rock is interpreted to represent the transition from the transgressive systems tract to the highstand systems tract. Thin sections analysis from each lithofacies quantified grain size and composition and identified a provenance. Modal analysis data from clastic lithofacies reveals subarkose to arkose sandstones with an accessory mineral suite including ilmenite, apatite, rutile, and zircon. Integrating the compositional data, particularly the accessory mineral suite, with detrital zircon dates of 1000 - 1300 Ma (Chiarenzelli et al., 2010) suggests that the Grenville Adirondacks in particular the AMCG suit and Lyon Mountain Granite are a likely source rock. Comparison with the Monkton Formations of Vermont suggest that these two units were deposited under similar sea level conditions and are therefore correlative. Provenance study suggests that they were both sourced form the Adirondack Mountains. The major difference is in their depositional environments as the Monkton represents deposition of predominantly tidally influenced deltaic environment. The environmental processes acting on the two units suggests that the paleogeography of the Iapetus margin in this area was an embayed coastline.

Volatiles are critical in understanding the history of the solar system. We conducted two case studies intended to further this understanding. First, we analyzed the presence of CO2 on Iapetus. Second, we evaluated aqueous alteration in CM chondrites.We studied the distribution, stability and production of CO2 on Saturn's moon Iapetus. We determined that CO2 is concentrated exclusively on Iapetus' dark material with an effective thickness of 31 nm. The total CO2 on Iapetus' surface is 2.3x108 kg. However, CO2 should not be present because it has a limited residence time on the surface of Iapetus. Our thermal calculations and modeling show that CO2 in the form of frost will not remain on Iapetus' surface beyond a few hundred years. Thus, it must be complexed with dark material. However, photodissociation will destroy the observed inventory in ~1/2 an Earth year.The lack of thermal and radiolytic stability requires an active source. We conducted experiments showing UV radiation generates CO2 under Iapetus-like conditions. We created a simulated regolith by mixing crushed water ice with isotopically labeled carbon. We then irradiated it with UV light at low temperature and pressure, producing 1.1x1015 parts m-2 s-1. Extrapolating to Iapetus, photolysis could generate 8.4x107 kg y-1, which makes photolytic production a good candidate for the source of the CO2 detected on Iapetus.We also studied the aqueous alteration of metal-bearing assemblages in CM chondrites. We examined Murchison, Cold Bokkeveld, Nogoya, and Murray using microscopy, electron microprobe analysis and scanning electron microscopy. Alteration on CM meteorites occurred within at least three microchemical environments: S-rich water, Si-rich water and water without substantial reactive components. Kamacite alters into tochilinite, cronstedtite, or magnetite. Sulfur associated alteration can form accessory minerals: P-rich sulfides, eskolaite and schreibersite.Additionally, we determined that there were two alteration events for some CM chondrites. The first formed a hydrated matrix prior to accretion, indicated by unaltered kamacite surrounded by a hydrated matrix. The second occurred after parent body formation. This event is indicated by large regions with consistent alteration features, surrounded by other regions of less altered material.

The lower Mount Rogers Formation (LMRF) is described by Rankin (1993) as a sequence of intercalated metabasalts and volcanogenic sediments with minor metarhyolite. We have chosen to examine the sequence of the LMRF units exposed along Elk Garden Ridge, a high shoulder between the summits of Whitetop Mountain and Mount Rogers in the Mount Rogers National Recreation Area in SW Virginia. This sequence represents an uplifted block of LMRF units enclosed by exposures of Whitetop and Wilburn metarhyolites. In the field, progressive lithologic changes can be observed walking up-section along Elk Garden ridge that are indicative of changes in lava compositions and eruptive environments. From the bottom of the section, massive basalts with distinctive 1-2 cm long swallowtail plagioclase phenocrysts grade into vesicular basalts, then into sheet flow basalts, followed by a thick sequence of aphyric and amygdaloidal pillow basalts. Further up section, eruptive products transition into rhyolitic ignimbrites and ash and lapilli tuffs. Boulders of cobble conglomerates near the middle of the sequence and sedimentary layers in between individual sheet flows suggest short periods of relative eruptive quiescence. The only unit broken out in the LMRF by Rankin (1993), Fees Rhyolite, is not observed in the field area, suggesting local differences in topography, eruptive products and eruptive styles across the outcrop area during the deposition of these eruptive products. Petrographically, the rocks reflect the regional greenschist facies metamorphic conditions with chlorite and epidote as primary metamorphic minerals, and unakite-like zones of mineralization. Relict plagioclase and pyroxene phenocrysts persist, as do primary igneous textures and structures. Compositionally, all of the rocks in the Elk Garden Ridge sequence are strongly enriched in alkali metals, with elevated Na2O and K2O contents, and high TiO2 in the basalts. Major and trace element systematics suggest that the chemical signatures of the metabasalts are primary controlled by shallow-level crystallization processes. The LMRF metabasalts share many compositional affinities with later (~570 Ma) rift-related basalts preserved in the Appalachians, suggesting that all of these lavas were formed by melting of a compositionally uniform mantle source, followed by shallow crystallization, despite being separated from one another by large stretches of time and space.