We studied the role of photochemical and microbial processes in contributing to the transformation of dissolved organic matter (DOM) derived from various plants that dominate the Florida Everglades. Plant-derived DOM leachate samples were exposed to photochemical and microbial degradation and the optical, chemical, and molecular weight characteristics measured over time. Optical parameters such...

The Sheepbed mudstone, Yellowknife Bay formation, Gale crater, represents an ancient lakebed now exhumed and exposed on the Martian surface. The mudstone has four diagenetic textures, including a suite of early diagenetic nodules, hollow nodules, and raised ridges and later diagenetic light-toned veins that crosscut those features. In this study, we describe the distribution and characteristics...

In this paper, we present a dynamic diagenetic model of the oxygen consumption pathways and cycling of carbon, nitrogen, manganese, iron, and sulfur in marine sediments. Sixteen dissolved or solid species are included in our model and the vertical transport processes accounted for are molecular diffusion, bioturbation, irrigation, and burial. Adsorption of dissolved species onto solid sediment ...

Surface carbonate sediments from sites on the Bahamas Bank with different seagrass densities were incubated across a range of O2 delivery rates, to study the controls on metabolic carbonate dissolution in these sediments. The results confirmed the 1:1 ratio between the rates of O2 consumption and carbonate dissolution, demonstrating that microbial respiration was the ratelimiting step in metabo...

The non-avian saurischians that have associated eggshells and embryos are represented only by the sauropodomorph Massospondylus and Coelurosauria (derived theropods), thus missing the basal theropod representatives. We report a dinosaur clutch containing several crushed eggs and embryonic material ascribed to the megalosaurid theropod Torvosaurus. It represents the first associated eggshells an...

Statistical analyses of geochemical data from ferromanganese nodule samples representing a broad area of the southeast Pacific Ocean indicate nodule compositions are controlled by four factors: (1) suboxic diagenesis; (2) oxic diagenesis; (3) hydrogenous precipitation; and (4) hydrothermal precipitation. The first three are identical to those identified in studies of nodules from the North Paci...