Devonian Middle

Figure 1. Atomic H/C vs. O/C ratios for asphaltenes from a variety of sources (M) petroleum crude (Alberta, Cretaceous, Carboniferous, and Devonian) ( ) Middle East crude (w) North and South American crude (+) shale oil (+) oil sands and (A) liquids from Kentucky coal at 4000 psi hydrogen and West Virginia coal at (O) 4000 psi, and (U) at 2000 psi hydrogen (21)...

Radon in soil gas is present everywhere throughout the province in all geologic terrains. Soil gas Rn concentrations range from a low of 0.1 kBq/m3 to a high of 207.0 kBq/m3 with a mean of 25.3 kBq/m3 (Fig. 3). The highest Rn soil gas concentrations are also associated with Middle-to-Late Devonian leucomonzogranite of the South... 

The identification of elevated U in the C-horizon soil and elevated Rn in the soil gas associated with the Middle-to-Late Devonian leucomonzogranite of the South Mountain Batholith are examples of the type of information generated by the... 

Sageman BB, Murphy AE, Weme JP, Straeten CAV, Hollander DJ, Lyons TW (2003) A tale of shales the relative roles of production, decomposition, and dilution in the accumulation of organic-rich strata, Middle-Upper Devonian, Appalachian basin. Chem Geol 195 229-273 Sarmiento JL, Toggweiler JR (1984) Anew model for the role of the oceans in determining atmospheric pCOj. Nature 308 621-624... 

The study area is situated in the Tobique-Chaleurs Zone, (TCZ) which contains early to middle Silurian sedimentary and volcanic rocks (Chaleurs group) that are disconformably overlain by Lower Devonian volcanic and sedimentary rocks of the Dalhousie and Tobique groups (Wilson 2004) and is bounded by the Rocky Brook-Millstream Fault to the northeast and the Mackenzie Gulch Fault to the north (Fig.1). The McCormack Brook Fault (a splay of the Rocky Brook-Millstream Fault) lies to the north of the... 

Wilson, R., Burden, E., Bertrand, R., Asselin, E., McCracken, A. 2004. Stratigraphy and tectono-sedimentary evolution of the Late Ordovician to Middle Devonian Gaspe Belt in northern New Brunswick evidence from the Restigouche area. Canadian Journal of Earth Sdence, 41, 527-551. 

Later volcanic/hydrothermal base metal-containing quartz-carbonate bearing Type IV veins are recognized as thin veinlets with bright yellow CL color. These are likely related to epizonal mineralization during the emplacement of middle Devonian felsic intmsions. 

The rocks of the TCZ are interpreted to have erupted in a transtensional continental rifting environment in the Late Siiurian to Middle Devonian. In this tectonic environment A-type granites are expected, and indeed the reiativeiy high Zr, Nb, and Y content in these rocks support this. However, many other geochemicai aspects of these rocks, i.e., high Ba, Rb, Th and K, are more typical of the I-type magmas that commonly occur in collisional settings. 

WEAVER (C.E.), 1956. Mineralogy of the middle Devonian Tioga K-bentonite. Amer. Min. 41, 359-62. 

Bituminous Substances. The distribution of hydrocarbons and other bitumens in some of the Paleozoic rocks of the area is shown in Tables I and II, the latter summarized after Swain (7). The presumed saturated hydrocarbons of the Ordovician, Silurian and Lower Devonian samples are measurably less than in the Middle and Upper Devonian samples. The presumed aromatic hydrocarbons are not as well differentiated. The pyridine-plus-methanol-eluted chromatographic fractions, arbitrarily taken as asphaltic material, also appear, like the aromatic fractions, to be controlled more by local variations than by geologic age. 

Table IV. Carbohydrate Components of Middle and Upper Devonian Rocks of Central Pennsylvania0...

In general these substances are widely distributed in the acid distillates but appear to increase in number at two stratigraphic levels (1) in the middle Silurian McKenzie Limestone and (2) in the middle Devonian shales. Furthermore, possible two- and three-ring aromatic or heteroaromatic structures show similar increases. There is also a rough correlation with the Kjeldahl nitrogen content of the samples (Table VI). 

Offshore neritic formations in the Paleozoic rock sequence probably include, on faunal and lithologic grounds, the Lower Ordovician Beekmantown dolomites, Middle Ordovician limestones, and Devonian Marcellus and Burket black shales (Table III). The first two are characterized by 0.1-0.4% organic carbons, very low organic nitrogen, and about 20 p.p.m. hydrocarbons but no carbohydrate residues. The Devonian offshore neritic black shales by contrast... 

The relative increase in carbohydrates in the Middle Silurian and Middle Devonian is suggested as resulting from a period of increased organic productivity during the deposition of those rocks. 

Newton Hamilton Formation, Middle Devonian, 2.5 miles northeast of Mt. Union, Mt. Union Quadrangle. 

Mahantango Formation, Middle Devonian, south Side of Juniata River, opposite Huntingdon, Huntingdon Quadrangle (not shown on map). 

Figure 4. Hydraulic-head cross-section, southern Saskatchewan, Canada, showing the deep drawdown of the hydraulic head by the South Saskatchewan River. This has enabled fresh water to penetrate deep into the basin and has resulted in the solution of the Middle Devonian Elk Point group halite beneath the region of drawdown. The solution process has been assisted by the influx of fresh water in the region of the Cypress Hills (which lie southwest of the line of the cross-section) which has penetrated aeep into the Devonian and is moving mainly into the line of the...

Figure 5. Hydraulic-head distribution in the Middle Devonian Keg River Formation of northern Alberta. Geology after McCamis and Griffith (303).

McCamis, J. G., Griffith, L. S., Middle Devonian Facies Relationships,... 

Vogel, K., Golubic, S. Breh, C. E. (1987). Endolithic associations and their relation to facies distribution in the Middle Devonian of New York State, U. S. A. Lethaia, 20, 263-90. 

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