Ordovician, Middle

Geologic Age Lower Ordovician Lower Ordovician Middle Ordovician Middle Silurian... 

Mobile Producing Company No. 1 Long Well, Centre County, Pennsylvania core samples from Lower Ordovician, Middle Ordovician and Middle Silurian (not shown on map). 

The direct water filling aquifer of upper coal seam is the lower Shihezi Formation sandstone fracture aquifer, the indirect filling aquifers are mainly the upper Shihezi Formation sandstone fracture aquifer, Taiyuan Formation karst fractured aquifer, Ordovician middle limestone and karst fractured aquifer. The direct water filling aquifer of lower coal seam is the Taiyuan Formation karst fractured aquifer, the indirect water filling aquifers are mainly the lower Shihezi Formation sandstone fracture aquifer and Ordovician limestone karst fractured aquifer. 

VMS deposits of the BMC occur within a Middle-Ordovician bimodal volcanic and sedimentary sequence in the northern Appalachians of New Brunswick, Canada (Goodfellow McCutcheon 2003). Volcanic rocks were emplaced between 472 and 455 Ma within an intra-continental back-arc basin (the Tetagouche-Exploits basin) at the eastern margin of the proto-Atlantic (lapetus) Ocean (van Staal et al. 2003). 

The BSC (part of the Dunnage tectonic Zone) formed in Late Ordovician to Early Silurian (i.e., during the Salinic Orogeny), and contains the accreted and subducted remnants of the Middle to Late Ordovician Tetagouche-Exploits back-arc basin. Consequently, the rocks of the BSC have... 

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. 

Age constraints and Grampian orogenesis of the Lower to Middle Ordovician Tyrone Igneous Complex, Northern Ireland... 

Abstract The Key Anacon Zn-Pb-Cu-Ag massive sulfide deposits contain more than two Mt of 0.22% Cu, 3.47% Pb, 8.41 % Zn, and 111 g/t Ag. These deposits occur in the hinges of parasitic F2 folds of Middle Ordovician felsic volcanic rocks. Zone refining of massive sulfide deposits (Cu-rich footwall to the Zn-Pb rich hanging wall) is controlled by temperature, pressure, metal ion concentrations, stabilities of soluble complex ions during transport, multiple hydrothermal episodes and mixing, and mineral free energies. 

The Key Anacon deposits lie on the eastern limb of the Portage River Anticline (Fig.1). They are hosted by an autochthonous sequence of Middle Ordovician felsic and mafic volcanic rocks and related sedimentary rocks of the Tetagouche Group, and overlie sedimentary rocks of the Miramichi Group,... 

The northeastern European oil shale deposits crop out on the northern coast of Estonia (Figs 2 and 3) with a strike N100-120 °E and a dip of c. 3 m/km towards the SSW. They occur as two stratigraphic units (Bauert Kattai 1997 Kattai Lokk 1998) (1) Middle Ordovician oil shale, also known as kukersite , from the German Kuckers (Kattai et al. 2000) and... 

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. 

Total Carbohydrates. The results of the phenol-sulfuric acid tests for total carbohydrates are listed in Table 1. The Lower and Middle Ordovician dolomites and limestones of this area did not yield detectable total carbohydrates, either because they are absent or because of metamorphic degradation. Palacas (5) and Palacas, Swain, and Smith (6), on the other hand, found traces of glucose and other sugars in Lower and Middle Ordovician rocks of Franklin County, Pa. southeast of the Mt. Union area. It appears that the early and medial Ordovician seas of the Mt. Union area may neither have been receiving much carbohydrate material from the lands nor was much being contributed by organisms to the bottom sediments. 

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... 

Middle Ordovician limestone, 1.5 miles southwest of Airydale, Mt. Union Quadrangle. 

Badiozamani K. (1973) The Dorag dolomitization model-application to the Middle Ordovician of Wisconsin. J. Sediment. Petrol. 43, 965-984. 

Grover G Jr. and Read J.F. (1983) Paleoaquifer and deep burial related cements defined by regional cathodoluminescent patterns, Middle Ordovician carbonates, Virginia. AAPG Bull. 67, 1275-1303. 

Read J.F. (1980) Carbonate ramp-to-basin transitions and foreland basin evolution, Middle Ordovician, Virginia Appalachians. AAPG Bull. 64, 1575-1612. 

Periglacial paleosols, unknown in Cambrian and Early to Middle Ordovician rocks, are found again... 

Strother P. K., Al-Hatri S., and Traverse A. (1996) New evidence for land plants from the lower Middle Ordovician of Saudi Arabia. Geology 24, 55-58. 

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