Sediments from the world's ocean floors and other water body basins hold a wealth of information about organic life as we know it. Organic Matter: Productivity, Accumulation, and Preservation in Recent and Ancient Sediments addresses focusing on the production, accumulation, and preservation of organic matter in marine and lacustrine sediments. Contributors to this important monograph cover a range of geologic ages from recent times back to the Permian Era, as well as temperature and organic matter types. This resource book will be of interest and benefit to petroleum explorationists and researchers, as well as oceanographers, marine and environmental scientists, sedimentologists, geochemists and paleontologists.

The Woodford Shale is an organic-rich formation found in southern Oklahoma and Kansas and has been extensively studied due to recent advancements in hydrocarbon recovery in mudrock successions. The controls on organic matter formation and preservation within the Woodford are not entirely clear in southern Oklahoma, but previous work points towards upwelling and anoxic bottom-waters as leading factors for the high organic content. This study was performed on a Woodford Shale outcrop located along Interstate 35 (mile marker 44) in Carter County, Oklahoma and contains the middle and upper Woodford succession. The integration of facies and chemical analyses, including hand-held X-ray fluorescence (HHXRF), inductively-coupled plasma mass spectrometry (ICP-MS), X-ray diffraction (XRD) and total organic carbon (TOC), were performed to construct sedimentologic-chemostratigraphic logs that allowed the establishment of a stratigraphic framework and evaluation of depositional parameters such as detrital input, primary productivity, and degree of oxygenation during the accumulation of the studied succession. The I-35 Woodford Shale outcrop can be divided into three main sequences (1, 2, and 3, from base to top), with sequences 2 and 3 further subdivided into subsequences (A and B), based on changes in chemostratigraphic indices proxies for detrital input, primary productivity, and degree of oxygenation, and accompanied facies associations. Sequence 1 is characterized by distal, pelagic settling sediments with 12-13% TOC deposited under conditions of stable anoxia/euxinia, with low-moderate primary productivity. Sequence 2A is defined by interbedded pelagic and hemipelagic deposits with TOC between 7-11%. It was deposited in more oxic environments because of decreased water depths, resulting in less preservation of organics. The continued accumulation of pelagic and hemipelagic deposits in Sequence 2B is accompanied by increased primary productivity following an increase in nutrient supply from upwelling and continental waters, which resulted in organic contents of about 12%. The hemipelagic deposits of Sequence 3A display the highest TOC in the entire succession (14-20%), as a consequence of productivity boosts due to riverine nutrient input, despite the presence of overall oxic bottom waters with occasional anoxic events. Sequence 3B accumulated in a low to moderately productive environment under strongly anoxic conditions, resulting in the lowest TOC in the entire section (2-8%). The detailed study of the I-35 Woodford Shale outcrop indicates that high organic content (TOC>10%) is found in settings where primary productivity is high, regardless of the bottom-water conditions. Primary productivity was boosted by riverine nutrient input associated with shallowing waters. The results of this study suggest that organic flux is more important than anoxia in the burial of organics in the sediments, with anoxia oftentimes being a consequence of high organic flux.

Organic-rich shales can serve as both source rocks and reservoir rocks. They are becoming increasingly important exploration and exploitation targets; however our knowledge of organic-rich shale properties is poor. Mudrock line (Castagna et al., 1985) suggests that Vp/Vs ratios of shale are around 2, but Vp/Vs ratios of organic-rich shale vary from 1.5 to 1.7. What remains to be studied is what factors impact this difference. Understanding Vp-Vs relations for organic-rich source rock is vital for seismic characterization of shale reservoirs. This thesis explores several issues related to Vp-Vs relations of organic-rich shale, such as Vp/Vs ratio, P-wave and S-wave velocity anisotropies, and three Poisson's ratios in a TI medium. Parameters that affect the Vp/Vs ratio in organic-rich shale are studied in two parts: mineralogy and organic matter. First, we studied Vp/Vs ratios, P-impedance, and velocity anisotropies in three types of organic-rich shales: silica-rich, clay-rich, and calcareous shales. Vp/Vs ratios change with mineral composition. A simple two-layer model built with the Backus average is used to explain why silica-rich shale has the highest shear anisotropy and calcareous shale has the highest P-wave anisotropy among the three types of organic-rich shale. Well logging data are utilized to separate the effects of quartz, clay, and calcite on Vp/Vs, P-impedance, and density. Second, total organic carbon (TOC) and maturation of organic matter significantly affect shale properties, because of a large contrast between elastic properties of the organic and inorganic components. Basin and maturation models are built to simulate hydrocarbon generation during organic-rich shale evolution, which provides us the fundamentals for analyzing products and their concentrations in different maturation stages. The effect of organic matter with different maturity levels on immature, mature, and overmature shale properties are studied with rock physics models, which are based on effective medium theory. The immature and mature shale modeled results are plotted with the Bakken shale samples, which increase the credibility of the overmature model. The modeling results suggest that higher maturity level and TOC lead to lower Vp/Vs ratio and stronger anisotropy. When TOC is high, maturity level dominates; when TOC is low, TOC dominates.

The environment of deposition of the Ohio Shale of the Appalachian Basin has been studied extensively using various geochemical proxies for each of its members. The accumulation of organic matter (OM) and its preservation in the Late Devonian-Early Mississippian black shales of central Kentucky have been studied extensively, especially the possible correlations between trace metal contents and water-column oxygenation. Previous work has centered on geochemical, petrographic, and isotopic analysis of samples collected throughout the central Appalachian Basin. Mechanisms for OM preservation include high productivity, enhanced preservation due to dysoxic or anoxic bottom waters, and a feedback loop due to high productivity that creates enhanced preservation through the periodic cycling and scavenging of essential nutrients. Usually, a combination of these factors results in the accumulation of enough OM to produce these black shales. This research shows the relationships between trace metal data and the environment of deposition of several cores taken along the eastern side of the Cincinnati Arch in the central Appalachian Basin. Whereas the indices do not all agree in every instance across the breadth of the study area, analyzed together a predominant environment of deposition has been inferred for the shales. The Sunbury Shale and upper part of the Cleveland Member of the Ohio Shale were deposited under euxinic conditions, the lower part of the Cleveland Member was likely euxinic in the northern study region and anoxic throughout the central and southern study areas, whereas the Huron Member of the Ohio Shale was deposited under a range of conditions, from oxic, to dysoxic, to anoxic.