Devonian

Abstract The Frasnian-Famennian mass extinction in the Late Devonian has often been considered as one of the major 5 extinctions through time. Conflicting interpretations for the cause of this extinction exist, but the role of volcanism is becoming increasingly appealing due to recent advances in radioisotope dating. New K-Ar and 40Ar/39Ar ages for the Viluy traps in Siberia suggest multiphase emplacement of the Viluy traps with an early phase likely contributing to the Frasnian-Famennian mass extinction

Bios101 Problem Set Three 1. (two points) A researcher is excavating a fossil bed from a Devonian reef, now fossilized in Pennsylvania. She encounters many species that are new to science. a) Which species concept would be most expedient and effective, in the process of collecting, naming, and describing what she finds? Phylogenetic species concept would be the most expedient and effective process of collecting, naming, and describing what she found. Phylogenetic relies on common ancestry

Genevieve Fault Zone (Hasenmueller and Comer 1994). During the Devonian while the New Albany Shale was being deposited, the Sangamon Arch was active causing the New Albany Shale to thin out (Hasenmueller and Comer 1994). The Media Anticline was also active during the time of deposition, this can be seen by the thinning

distinct out groups or sister taxa to all living jawed vertebrates. Placoderms evolved from agnathan (jawless) fishes in the Silurian period, about 425 million years ago. They first appeared in the Early Silurian and diversified dramatically during the Devonian and Carboniferous periods and became extinct in Permian.

fundamental to finding why speciation declined during the late Devonian biodiversity crisis. Potential causes of speciation include reproductive isolation and geographic isolation, which is also known as vicariance. Stigall studied three different species of shallow marine invertebrate organisms and determined their speciation by combining each species’ geography and phylogenetic backgrounds. Measurements of the biodiversity

1- Marcellus Shale:- The Marcellus shale is a Middle Devonian primary source rock in the Appalachian basin as well as an unconventional reservoir rock.The Marcellus shale is produced through the implementation of horizontal drilling and hydraulic fracture stimulation. The Marcellus shale has been one of the most important developments in gas production over the past few years. Having a good understanding of what this gigantic gas reservoir can do to shape the future of the natural gas

(a) Shows New England Fold Belt, highlighting the location of Rockhampton-Gladstone District with Devonian –Early Carboniferous tectonic features. (b) shows the map of Wandilla and Shoalwater terranes at same district. Image source (Fergusson, Henderson and Leitch, 1990). Stratigraphy The Doonside formation of the Wandilla terrane is comprise of mudstone

(Phalen 1). Both series are represented in the Johnstown quadrangle. The Pennsylvanian series, however, covers most of the region, while Mississippian rocks appear only at the surface along deeply eroded anticlines. Below these Carboniferous rocks, Devonian rocks are also exposed. These rocks can be found along the northern edge and southeastern margin of the plateau, where strata is nearly vertical. These two geologic systems have also been subdivided into numerous formations categorized according

the passive margin converted to an active margin most probably about Late Devonian to Late Cretaceous through the subduction of the exotic allochthons beneath the North American plate. The late Jurassic to Cretaceous subduction of (Sevier and Laramide Orogeny) representing as a period of the back thrust, intraplate thrusting, behind a magmatic arc on the upper plate near or on its westernmost margin from the latest Devonian until the Cretaceous. Hildebrand (2009, 2013) cast doubt the back thrust interpretation

More countries in the world extract the methane from coal beds and today it is established in a number of countries throughout the world, including the USA, Australia, China, India and Canada. The advantage of the coal is almost pure carbon and its reservoir character is fundamentally different to conventional gas plays. The Coalbed methane refers to methane that is produced in association with coal, and CBM reserves are located wherever large deposits of coal are found. CBM is formed through organic