Sequence stratigraphy and a revised sea-level curve for the Middle Devonian of eastern North America

Determining the source and genetic fingerprint of natural gases using noble gas geochemistry: A northern Appalachian Basin case study

“…The stratigraphic sequence reprinted from Jenden et al (1993) is presented in Figure 1B, whereas more complete summaries of Appalachian sedimentation and stratigraphic sequences are available elsewhere (Straeten et al, 1994;Brett and Baird, 1996;Brett et al, , 2011Lash and Engelder, 2011;Straeten et al, 2011). This Appalachian Basin sedimentary sequence is underlain by Precambrian crystalline basement rocks of the (Grenville province) Canadian shield ( Figure 1B).…”

“…The transition from Upper Silurian to Lower Devonian is composed of the Helderberg Group (layered dolomites and limestones commonly lost in western New York) and Tristates Group, consisting of the Oriskany Sandstone and Onondaga Limestone, which lies directly beneath the Hamilton Group ( Figure 1B) (Straeten et al, 1994Baird and Staeten, 1999).The Hamilton Group is an eastward-southeastward-thickening wedge of marine sediments, including the Marcellus Formation (lowermost Hamilton). The Marcellus Formation accumulated during the early phases of the Acadian orogeny (∼400 Ma) and has two distinct calcareous and iron-rich black-shale members (i.e., the Union Springs [lower] and Oatka Creek [upper]) interrupted by the Cherry Valley Limestone Member (Straeten et al, 1994Baird and Staeten, 1999;Lash and Engelder, 2009;Brett et al, 2011).…”

Increased stray gas abundance in a subset of drinking water wells near Marcellus shale gas extraction

“…Previous researchers have characterized the region's geology and aquifers (19)(20)(21)(22)(23). Briefly, the two major bedrock aquifers are the Upper Devonian Catskill Formation, comprised primarily of a deltaic clastic wedge gray-green to grayred sandstone, siltstone, and shale, and the underlying Lock Haven Formation, consisting of interbedded fine-grained sandstone, siltstone, and silty shale (19,22,24). The two formations can be as deep as ∼1,000 m in the study area and have been exploited elsewhere for oil and gas historically.…”

Microhabitat complexity—an example from Middle Devonian bryozoan-rich sediments in the Blankenheim Syncline (northern Eifel, Rheinisches Schiefergebirge)

“…The transition between the Junkerberg and Freilingen formations probably coincides with the early highstand systems tract (Eif-GivA) of the revised sea-level curve for eastern North America given by Brett et al (2011). Sequences occurring in the RSG east of the Rhine, representing different facies settings, may have developed synchronously.…”