Coals Devonian

FIGURE 15.7 Secondary changes in the total group composition of soluble organic matter as a result of simulated water washing extracts of the Miocene lignite and shale (both of the Bechatow open cast mine, Poland), the Upper Devonian shale (the Holy Cross Mountains, Poland), and the Upper Carboniferous bituminous coal (the Upper Silesia Coal Basin, Poland). 

Near term options include primarily the unconventional natural gas resources (Western tight gas sands, Eastern Devonian gas shales, geopressured aquifers, and methane from coal deposits). Mid-term options include coal gasification (peat... 

These include (1) tight sandstones, (2) Devonian shales. (3t geopiessured zones, (4) deep basins, (5) gas associated with coal seams, and (6) gas in the form of methane hydrates. 

Degasification of coal, gas from Devonian shale, gas from tight formations, gas from geopressured zones, gas from biomass and gas from in-situ coal gasification, etc. 

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)...

Fig. 2-26. Results obtained by the CHIM method over an oil deposit in Byelorussia and schematic geological section 1- Permian-Cretaceous-Quatemary clays, sands, coals 2- marly siliceous clay formations 3- Carboniferous sand-clay formations 4- middle-late Devonian sandstones, aleurolites, marls 5- oil deposit (reproduced with permission from Ryss et al., 1990).

Before the arrival of humanity, the longer-term controls were burial of carbon as carbonate, as methane hydrate in sediment, as gas, as coal, or as reduced organic matter (including charcoal). Before the Devonian, fire would have been impossible, except perhaps on lightning-hit microbial peat bogs after drought. 

Figure 3, Solid-state 13 C-NMR spectra of kerogen and coal samples from Upper Devonian black shales (right) and from other locations as indicated (left).

Claisse Fluxer Analysis - Lithium tetraborate or metaborate fusion for the dissolution of rocks has been in use for many years. The Claisse Fluxer fusion device simply makes this fusion automated. We have used the method in the past for the fusion of coal and fly ashes (10,13). Oil shales can be dissolved by this method without pre-ashing. Once the solution is prepared, it may be analyzed for the most part by ICPES or by AAS. Analysis of U.S.G.S. Devonian Ohio shale SDO-1 by fusion followed by AAS or ICPES measurements is illustrated in Table III. 

The major areas of coal distribution are principally in the Northern Hanisphere with the exception of Australia, the southern continents are relatively deficient in coal deposits. This relatively uneven distribution is the result of the deposition and maturation of the plant at different times in the geological past in predominantly tropical latitudes, and the subseqnent drift of the continents to their present-day positions. The oldest coals of any economic significance date from the Middle Carboniferous Period— the earliest geological strata in which coal has been identified are of Devonian age bnt they are generally of little economic significance. With the exception of parts of the Triassic Period, major coal deposits have been forming somewhere in the world throughout the last 320 million years. Sedimentary sequences of the last 2-3 million years do not contain coal— there has been insufficient time for them to develop from plant debris. 

However, not all regions have coal reserves. Generally, regions where post-Devonian sediments were not deposited or have been completely eroded have no coal whatsoever, for example, Scandinavia and much of Africa. In addition, rocks with the potential for coal bearing, once deposited, may have been eroded away and some regions which do have rocks with the potential for coal bearing may be buried deeply under younger sedimentary sequences and cannot be worked economically. 

Commercially important coals are not usually found in strata older than Mississippian age, although Devonian coals have been mined in Europe (Table 1.3). Some Permian coals are mined in the United States, but coals of that age have much more important reserves in other parts of the... 

It should be noted, however, that deposits of vegetable matter are not limited to any particular era or period, but while these deposits occur even in pre-Cambrian rocks, the plants (i.e., terrestrial plants) that were eventually to become coal were not sufficiently abundant until the Devonian Period and it appears that such deposits really became significant during the Carboniferous Period. 

Coal is the compacted and preserved ranains of plant matter and when plant life containing cellulose-rich stems and leaves is highly abundant and special conditions exist (usually anaerobic conditions)—the plant matter does not totally decompose and is preserved in fossilized form. These types of plants had evolved by the Devonian Period and many coal deposits in Europe and North America date from the Carboniferous Periods of the Paleozoic when these areas were covered with forests dominated by large ferns and scale trees. 

Coals are formed in swamps under warm climatic conditions that promote rapid vegetative growth. Coal deposits are generally associated with mountain-building events and deltaic environments. Coals can be traced to the Devonian period, when woody plants first evolved, about 370 million years before the present. 

The strata in the area between central Longmenshan fault and frontal Longmenshan fault from old to new are (a) Devonian Limestone and dolomite (b) Carboniferous limestone and marl (c) upper Permian flint limestone, shale and coal seam, lower Permian limestone, dolom-itic limestone (d) shale, lithic sandstone and coal seam, purple-gray mudstone, siltstone, and gray dolomitic limestone of Xujiahe group in Triassic system (f) Holocene sandy loam and loam. 

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