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The Austin Chalk Formation in south Texas and northern Mexico represents an "impure" onshore depositional chalk deposited within an environmental framework characterized by distinct paleobathymetric variations. Relatively shallower water, highly fossiliferous chalks containing appreciable amounts of primary metastable carbonate material were generated on a platform coincident with the ancestral San Marcos arch. Deeper water basinal settings off this platform were sites of more typical chalk deposition which periodically received influxes of adjacent platform sediments. Abundant primary metastable carbonate constituents significantly complicated Austin Chalk diagenesis. Porosity trends and isotopic geochemistry confirm this fact and indicate the Austin Chalk underwent a greater degree of diagenesis compared to typical European chalks. Porosity in the buried Austin Chalk was destroyed relatively quickly earlier in its burial history and at shallower burial depths relative to typical North Sea chalks. Overall, the Austin Chalk exhibits an isotopic imprint distinctly different from European chalks but similar to marine limestones. Major processes that promoted Austin Chalk diagenesis and porosity reduction were physical compaction, fresh water dissolution/cementation, burial stabilization of primary aragonite, pervasive pressure solution and concomitant cementation, and tectonism. Where these processes operated depended on depositional setting, burial history and proximity to regional tectonism. Outcropping Austin Chalk in south Texas underwent extensive porosity reduction due to early physical compaction and later fresh water dissolution and cementation by non-ferroan calcite. Burial diagenetic effects are not conspicuous. Very low bulk iron and strontium concentrations support petrographic evidence for fresh water diagenesis. Buried chalks in south Texas underwent early physical compaction, early burial stabilization of aragonite (when present) and related cementation, and later deep burial pressure solution. Cements are predominantly ferroan calcite. Mexican outcropping chalks show a burial/diagenetic history similar to that for Texas subsurface chalks but were more deeply and deformed by Tertiary folding. Intense deformation of Parras Basin chalks partially to nearly totally obliterated primary depositional and secondary burial diagenetic fabrics and produced a matrix of micrite/microspar crystals elongated parallel to tectonic stress direction. Some fresh water cementation occurred attendant to this tectonism. Austin Chalk exhibits increased destruction of primary matrix components with progressive burial diagenesis. Concomitantly, Oxygen-18 becomes progressively depleted in response to pressure solution. Anomalous (delta)O('18) values at similar burial depths imply that factors other than burial depth influenced Austin Chalk diagenesis. Early burial stabilization of abundant primary aragonite in some samples may have created a lithified sediment framework sufficient to retard later pressure solution effects. Distribution of fractures in the Austin Chalk appears controlled by the abundance of argillaceous material. Highly argillaceous chalks do not fracture.

Part I. Petrographic examination of Lower Ordovician limestone and dolomite fabrics indicates that the sedimentary column in central Tennessee reflects multiple seaward progradation episodes of peritidal sediments across a broad, shallow shelf. The following sedimentary types were recognized: columnar, spheroidal, thrombolitic, domed, laminar and crinkled algal sediments; intramicrites, intrasparites, pelmicrites, laminated micrites rich in clay and silt, algal-bound biolithites, oosparites with either tangential or smaller radial ooids, oomicrites and orthoquartzites. Vertical distribution of these sediment types within the stratigraphic column indicates that normal marine, transgressive waters were gradually displaced by progressively more saline waters originating from prograding evaporative tidal flats and restricted lagoons. The waning phases of such episodes are commonly marked by sheet-like deposits of coarse, unimodal sands derived from the distant craton. Because these sheets were deposited and reworked on tidal flat sediments during periods of maximum subaerial exposure, they are reliable lithostratigraphic markers. An isopach map of the upper Mascot Formation and additional evidence of progressive shallowing throughout the depositional area suggest that the Nashville Dome may have become a positive feature during the early Ordovician. Continued uplift coincided with the development of the Sauk unconformity. Part II. Mascot Formation dolomite is made up of several genetically distinct dolomite types that are recognized by their combined petrographic, cathodoluminescent, and geochemical characteristics. Cathodoluminescence, however, is the key investigative tool used to distinguish and classify dolomite types into 2 basic categories and 5 subcategories: NZh, and NZc dolomite are subcategories of NZ dolomite rhombs exhibiting Non Zoned luminescence; Z(,1), Z(,2), and Z(,3) dolomite are subcategories of Z dolomite exhibiting Zoned luminescence and three or more concentric luminescent zones. Based on macrotextural and petrographic relationships observed among dolomite categories, most NZh, NZc and, Z(,1) dolomite grew penecontemporaneously on evaporative tidal flats and following deposition of prograding peritidal sediments, within shallow, schizohaline, subsurface sediment environments. Recognizable recurrent sequences of abundant luminescent zones occurring in Z(,2) dolomite can be correlated in subsurface samples throughout a geographic area exceeding 1300 km('2) and a stratigraphic thickness exceeding 250 meters. Additional evidence obtained using an established microstratigraphic sequence of these luminescent zones records the southward movement of regional dolomitizing solutions both laterally and upward through karsted carbonate sediments. These, other petrographic, and geochemical data, indicate that regional dolomitization occurred within subsurface marine-meteoric water mixing zones that formed during the marine inundation of an incipient, subareally exposed, Nashville dome. As southward-transgressing middle Ordovician seas drowned topographically high meteoric recharge zones, dolomitization ceased. Following at least one additional karsting episode, Mississippi Valley-type mineralizing solutions invaded the study area. These transported zinc, iron, and sufficient magnesium to precipitate Z(,3) dolomite before and immediately following sphalerite precipitation. The common occurrence of multiple dolomite overgrowths exhibiting several luminescent characteristics, and other petrographic evidence, indicate that maximum permeability pathways for subsurface fluids were generated during the earliest karsting episode following collapse of multiple, thin and permeable grainstone horizons. These pathways channeled subsurface fluid flow from the end of early Ordovician time to at least Mississippian and possibly Pennsylvanian time.

Glaciogenic rocks are present throughout the world, in strata of all ages. Where thought to represent glacial marine or glacial aquatic deposition their interpretation has been hampered by the lack of a sedimentary model based upon modern glacial marine processes. A model constructed from the study of Antarctic marine sediments and Pleistocene marine sequences exposed in the Puget Lowlands is used in this thesis to interpret Early Proterozoic (middle Pre-cambrian) glaciogenic rocks. Possible tillites were studied in the Gowganda Formation, Ontario, the Headquarters Formation, Wyoming, and in the Black Hills. Antarctic glacial marine sediments reflect the interaction and relative importance of glacial, marine, and gravity-driven sedimentary agents. Subglacial deposits on the continental shelf exhibit no indication of marine current action. Glacial marine tills on the continental shelf and slope display both glacial and marine characteristics. Marine current deposits are also present on the continental slope. Sediment gravity flow deposition of several kinds occurs, principally on the continental slope, and these sediments are interbedded with glacial and marine sediments. Sediment texture, the kinds of sedimentary structures, pebble characteristics, and sedimentary associations are the major criteria used for distinguishing these sediments types. The Gowganda Formation in northern Ontario is a thick, widespread unit that has long been thought to represent glacial deposition. A sequence of rocks representing pre-glacial and periglacial sedimentation, subglacial and glacial aquatic conditions, and post-glacial deposition is typically present. The glacial unit contains both basal and floating ice deposits. This formation is interpreted as representing one major advance and retreat of a large grounded and floating ice sheet. Local fluctuations of the grounding line, and of the retreating ice margin probably occurred but there is no need to invoke more than one glaciation to explain these deposits. The Headquarters Formation in southeastern Wyoming contains tillites that are interbedded with a variety of nonglacial sediments (fluvial-deltaic deposits, turbidites, etc.). This unit probably represents deposition in a nearshore setting under frigid climatic conditions. There is no evidence for the presence of a nearby large ice mass. Metaconglomerates in the Black Hills are of unknown origin. The presence of lonestones in argillites and gradational contacts between units suggests glacial aquatic deposition. There is no evidence in the deposits studied which indicates that a continental ice sheet covered North America at that time; though a large ice sheet was present in northern Ontario.

Over 24% of the ice surface area covering East and West Antarctica drains into the Ross Sea and supplies the Ross Ice Shelf. The dominant proportion of this ice originates from the West Antarctic subcontinent. Thus, any change in the glacial regime in West Antarctica, and to a lesser extent East Antarctica, may well be preserved in the thick sequence of sediments underlying the Ross Sea. The Oligocene through Pliocene portion of this glacial marine section is studied using depositional models derived from the abundant piston core data in the region. The sedimentologic evidence from the Ross Sea glacial section is combined with evidence from the literature to establish a glacial chronology for the East and West Antarctic subcontinents. The West Antarctic archipelago was completely glaciated by late Oligocene time. This condition is indicated by the youngest occurrence of stripped soil-minerals in upper Oligocene marine sediments in the central Ross Sea, which are immediately overlain by sediments of the same age containing the oldest IRD in the region. Ice shelves then began to develop around these islands in the late Oligocene and early Miocene, as evidenced by fluctuations in the percentages of IRD (ice-rafted debris) and by the occurrences of zones containing visually massive pebbly mudstones within the Ross Sea section. These ice shelves coalesced to form an ice sheet over West Antarctica, including the Ross Sea, in the middle Miocene. IRD percentages in the Ross Sea glacial section increased rapidly at this time and remained high through the late Miocene and early Pliocene as the Ross Ice Sheet developed and expanded. The initial coalescing of the West Antarctic ice sheet probably corresponds to Vail and Hardenbols' (1979) eustatic sea-level drop at 14 myB.P., in the mid Miocene. Renewed growth and expansion of the Ross Ice Shelf is indicated in the latest Miocene and early Pliocene Ross Sea glacial section by high percentages of IRD (20-40%), deposition of a basal till, and finally by erosion of a portion of the Pliocene glacial section over nearly the entire Ross Sea continental shelf. This ice shelf expansion correlates with the eustatic sea level drop reported at 6.6 myB.P., in the late Miocene. It also corresponds to climatic changes in southern South America and New Zealand and to changes in oceanic circulation patterns. Development of an ice sheet over West Antarctica in the middle Miocene (14 to 10 myB.P.) requires an earlier data of formation for the East Antarctica ice sheet. This is supported by new evidence from subglacial volcanism (Stump et al., 1980). These data suggest that the continental East Antarctic ice sheet formed at 29 myB.P. causing the major eustatic sea level drop reported for that time. The majority of the data reported from southern ocean DSDP drill sites supports a glacial build up in the middle Miocene. If the new dates of ice sheet formation are accepted then all of this DSDP data is related to the development of the West Antarctic ice sheet, not the East Antarctic ice sheet, as generally assumed.

This study simulates thermal maturation of liptinitic and humic organic matter (Phosphoria shale and Rattlesnake Butte lignite) by isothermal pyrolysis at temperatures of 230(DEGREES), 275(DEGREES) and 325(DEGREES)C for heating times as long as 5000 hours, and programmed temperature pyrolysis using both Chromalytics MP-3 and Rock-Eval instruments. Comparison of artificially and naturally matured Phosphoria starting materials suggests that natural maturation is simulated best by the experiments conducted at 230(DEGREES) and 275(DEGREES)C. The character of the bitumen from experiments using kerogen with simulated maturities in the oil generation range (greater than about 0.5%R(,o), vitrinite reflectance) are quite similar to Phosphoria crude oils, especially in the saturated hydrocarbon fraction. Absence of steranes and triterpanes in the saturated fraction from experiments using previously solvent extracted Phosphoria shale suggests that these large biological marker molecules are not released from the kerogen during heating. They were apparently present only in the native bitumen, probably inherited from the original depositional environment. There does not appear to be an effect from the presence or absence of mineral matrix on the amounts and character of the degradation products. Excess water in the experiments results in larger amounts of CO(,2), hydrocarbon gases and bitumen. The experiments with added water had slightly higher relative amounts of the aromatic fraction in the bitumen. During the early stages of maturation, the liptinitic and humic organic starting materials generate hydrocarbon gases at about the same rate, though the humic material yields much more CO(,2) during the same period. Determination of pseudo-activation energies for the kerogen-to-bitumen conversion step by programmed temperature pyrolysis of artificially and naturally matured liptinitic-rich kerogen is about 26 to 30 Kcal/mole, regardless of the maturity of the kerogen. The pseudo-activation energy of the lignite is about 22 Kcal/mole, suggesting that the humic material contains more low energy bonds, probably those with oxygen such as ether bonds. Applying the relationships between the artificially matured kerogen and the products of thermal maturation seen in the laboratory simulations to geological situations will permit a better evaluation of the changes which have occurred during the natural maturation process. This should make possible more accurate assessment of source-rocks for both type and amounts of generation product and should be important for petroleum exploration in predicting where and how much oil or gas may be in a specific volume of rock.

Numerous textural and heavy mineralogical analyses have been performed on sand samples from the northeastern Texas Gulf coastal region. Analyses of local point-bar samples result in the delineation of major river and sources, with average histograms of grain-size data showing combinations of discrete modes characteristic of each river. Similar study of area coastal sands allows distinction of river, beach, and fluvial- and wave-dominated deltaic sands on the basis of texture. Kyanite/garnet/hornblend + pyroxene ratios are an excellent criterion for evaluating source contributions to the coast. Combining approximated age (radiocarbon) dates and heavy-mineral ratios results in the delineation of two distinct sand types. Spatial relationships between the two are used to develop a model for barrier formation. The model is then compared with previous models, applied to local problems of beach erosion, and discussed with regard to the ancient record.

The Aptian to Cenomanian aged Ain Tobi Formation of northwest Libya and adjacent Tunisia is a shallowing upward platform deposit. It has been studied in detail long its outcrop in the Jebel Nefusa of Tripolitania and with well control in adjacent areas north and south. The Ain Tobi was deposited in five depositional environments which roughly parallel the present coastline. The three southernmost depositional environments extend for about 400km. from the present coastline south. Two northern environments are in offshore areas where little data are available. The sedimentary environment of the Ain Tobi is similar to Cenomanian platform deposits of southern France and Italy. The southernmost restricted platform environment consisted of shallow lagoons--sites of evaporite precipitation, intervening pellet mud shoals, and rare ooid-bioclastic sand shoals. Rocks include bedded gypsum, dolomitic limestone, marl, and shale. Mudstones and wackestones are the dominant textures. To the north a slightly restricted to open platform environment consisted of clean to muddy carbonate sand flats, ooid-bioclastic sand shoals, and deposits which graded into the restricted environment represented by algal laminated sediments and evaporites. Rocks from the slightly restricted to open platform include dolomite, sandy and/or argillaceous dolomite, siliceous dolomite, quartz sandstone, shale, and chert. Wackestones and packstones are the dominant textures. The platform margin environment lay farthest north approximately coincident with the present coastline. The Ain Tobi Formation had a ramp type margin consisting of sand flats, ooid shoals, and oyster and rudist biostromes. Dolomite is the dominant lithology, wackestones to grainstones are the dominant textures. Cenomanian time equivalents of the Ain Tobi in the offshore Gabes-Sabratha Basin include rocks consisting of dolomitic marls with planktonic foraminifera and platform margin detritus indicating a basin-slope environment. In addition, a paleotopographic high capped by rudist biostromes similar to those of the platform margin environment exists here. Dolomitization of the Ain Tobi is probably the result of a seepage reflux mechanism which acted at the time of deposition. A dorag mechanism may have been of secondary importance in dolomitizing the Ain Tobi, but of major importance in dolomitizing the overlying section.

Continental to deep-marine facies transitions, eustatic versus tectonic controls on basin-margin stratigraphy, shelf-edge unconformities, and depositional mechanisms along basin margins were investigated for Middle Eocene strata, San Diego County, California. Coeval fan delta, nearshore, offshore, shelf, slope, submarine canyon, and proximal submarine fan facies indicate steep paleobathymetric gradients. Mass-transport processes dominated the canyon-fan system: sandy and muddy debris flows, fluidized and liquefied flows, grain flows, high- and low-density turbidity currents, slumps, and rockfalls. The submarine canyon fill is tripartite and fining-upward, representing progressive detachment from a nearshore source. Planar- to convolute-laminated sandstone overlies a basal amalgamated pebbly sandstone. Lithologically variegated cross-cutting channels to 100's of meters wide cap the sequence. A qualitative sand budget indicates the pebbly sandstone bypassed the wave zone, directly tapping an unsorted fluvial source. Residual lag deposition predominated. The coarsest fraction (0 to 3 (phi)) was also trapped and deposited by traction in the paralic zone, whereas intermittent suspension removed the 3 to 4 (phi) component onto the shelf. Size-sorting occurred downcanyon. Traction and intermittent suspension characterized inner-fan channel deposition. Lag plus traction and suspension constituents distinguish mid-fan channels. Eustacy primarily controlled stratigraphic development. A depositional "hemicycle" of 9-10 m.y. corresponds to Vail et al.'s (1977) supercycle Tb. Punctuation by marine progradation was concurrent with an intervening eustatic fluctuation. Subaerial notching of the shelf edge coincided with the Late Penutian sea level drop. During the subsequent rise, canyons eroded headward and a thin, retrogradational sequence was deposited. Coarse-grained, nearshore accumulations of the Early Ulatisian highstand were flushed basinward, responding to a slight sea level fall; submarine fan progradation resulted. After minor retrogradation, a Late Ulatisian to Early Narizian highstand induced thick, progradational development. Similar stratigraphic sequences developed simultaneously in other Pacific margin coastal basins. This suggests primary eustatic control on sedimentation and/or simultaneous continental-margin uplift and subsidence. Variations in rates of and absolute paleodepth changes indicate local tectonics. Combining global sea level fluctuations and resultant depositional patterns can provide a powerful tool in frontier exploration.