Introduction Cyclic Sedimentation of Appalachian Devonian and Midcontinent Pennsylvanian Black Shales: Analysis of Ancient Marine Anoxic Systems

Trace-metal covariation as a guide to water-mass conditions in ancient anoxic marine environments

Patterns of sedimentary trace-metal variation can provide information not only about benthic redox conditions, but also about other water-mass properties in ancient marine depositional systems. Trace metals such as Mo, U, V, and Re display conservative concentration profi les in the global ocean but varying concentration profi les in modern anoxic silled basins (e.g., the Black Sea, Cariaco Bas...

Environmental Reconstruction of Anoxic Marine Systems: Core Black Shales of Upper Pennsylvanian Midcontinent Cyclothems

Environmental analysis of offshore shale members of Upper Pennsylvanian Midcontinent cyclothems was undertaken using a combination of high-resolution X-radiography, petrography, and geochemical analyses. A hierarchical sampling strategy permitted investigation of (1) broad stratigraphic and geographic patterns of compositional variation through analysis of three shale members (Hushpuckney, Star...

The Utility of X-Radiography for Generation of High-Resolution Paleoclimatic Proxy Records from Black Shales, with Examples from Core Shale Members of Upper Pennsylvanian Midcontinent Cyclothems

Ancient black shales have considerable potential for generation of long, high-resolution paleoclimate proxy records, given the availability of a geochemical proxy that can be easily measured. Owing to substantial differences in density between the siliciclastic matrix of black shales (2.6-2.7 g cm-) and the major non-clastic components, i.e., organic carbon, Fe-sulfide, and phosphate (ca. 1.0-1...

Isotopic evidence for Fe cycling and repartitioning in ancient oxygen-deficient settings: Examples from black shales of the mid-to-late Devonian Appalachian basin

Geologic consequences of globe-encircling equatorial currents

Many black shales, phosphorites, and cherts that formed at low paleolatitudes on the North American continent during the late Paleozoic were a direct consequence of equatorial upwelling and an equatorial undercurrent in an ocean that spanned much of the globe. In equatorial parts of modern oceans, wind stress divergence leads to high surface productivity. Sinking organic matter is remineralized...