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Problem 2 (REVISION)
Problem 2 Presentation
Problem 3 - coals
Problem 3 Paper
Problem 4 - Rifting
Problem 4 - Synthesis Paper
Problem 5 - Climate Change
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Problem 3 - coals
Here's the final powerpoint I presented.
Below is just the text, in case someone can't see the powerpoint correctly. It's also probably a good outline for the paper, AJ. :)
Where are major coal deposits located in the Eastern USA?
What were the conditions that prompted these coals to form?
What is the specific facies sequence in these coal deposits?
What can the sequence tell us about paleoenvironment?
What is Coal?
Metamorphic, combustible rock formed from ancient peat deposits
Peat: partially decayed vascular organic matter
Stagnant water + anaerobic conditions = environment in which aggradation or organic matter exceeds degradation
Add pressure, heat, and time… Coal!
*Maybe have this above section a part of the intro. Begin by telling what coal and peat is, and then explain that we are going to be looking at specific coal definitions and their paleoenvironments.
Conditions for Deposition
Not necessarily tropical: Ireland, Rhode Island have peat forming, clearly not tropical places.
Dense vegetation must accumulate and be covered in mud or sediment, away from oxygen and bacteria, to begin coal formation
“A major extinction of peat-forming plants occurred at the end of the Middle Pennsylvanian in the lowland tropics of North America, due to changing climatic conditions, probably protracted moisture deficits or exaggeration of seasonal dryness” (DiMichele, 1996).
The explosion of luxuriant plant growth and coal bed formation that occurred 286 - 360 million years ago is the "Carboniferous Period.“
Most coals from the Pennsylvanian Period (320 to 286 million years ago) (Cengage, 2003).
Low and flat land, rivers flowing westward.
Densely vegetated floodplains and coastal swamps, where peat accumulated.
Rivers periodically overflowed producing lacustrine swamps, burying and compressing the peat under thick layers of sand and mud.
These layers formed specific sequences…
Coal commonly occurs in this sequence of sedimentary strata.
Formed from repetition of a pattern of sediment layers.
*Different for each area of coal deposits
In general, driven by eustatic sea level changes, or thrust loading, or a combination.
An idealized Pennsylvanian cyclothem: sandstone, shale, limestone, underclay, coal, shale, limestone, shale.
In any one locality, cyclothems commonly repeat tens of times with each cycle of deposition accumulated on a previous one (Nevins, 1976).
Where in the Eastern USA?
Relatively high-grade coals
Kansas Coals(Interior Province)
Illinois Basin(Interior Province)
Appalachian Basin(Eastern Province)
Empiric Sea in the mid-continent North America.
This sea transgressed and regressed repetitively over millions of years.
Marine carbonate cyclothems accumulated on a relatively stable platform affected only moderately by collision tectonics of North American margins.
These cycles are eustatic, caused by the change in sea levels (Klein, 1989).
Peat deposited as sea level rose.
More than 100 cyclothems in the Pennsylvanian and Lower Permian rock succession of Kansas (Moore, 1964).
Origin of depositional environment: evolution of resurgent foreland basins in Paleozoic time.
The Appalachian Basin was an equatorial foreland basin bounded by the Allegheny Range, Central Pangaea Mountains to the southeast, and open westward to the sea
Depositional environment: a large wetland complex drained by a fluvial system containing a mosaic of channels, freshwater siliciclastic and carbonate lakes, and peat swamps on a siliciclastic floodplain (Garcés, 1996).
Evolution of connected fluvial systems controlled by subsidence in an active foreland basin, rather than to short-term climatic change or eustacy.
Base level changes in the fluvial system as influenced by eustacy are considered only a very minor control of the Appalachian cyclothem pattern.
There are about a hundred successive cyclothems in West Virginia (Appalachian basin) (Nevins, 1976).
Projected time scale of deposition of one 'cycle' = about tens of thousands of years (Garcés, 1996).
Linked to Appalachian Basin through the same erogeny and the building of the foreland basins.
Also close to Kansas deposits, and thus affected by changes in sea level and containing some marine sediments (limestones).
Cyclothems are intermediate between the two end-member processes of flexural tectonics and glacial eustasy characterizing Appalacian-type cyclothems and Kansas-type cyclothems (Klein, 1989).
Drop in sea level = steeper river gradient = less pooling
Rise in sea level = shallower river gradient = more pooling.
50 successive cycles in Illinois (Nevins, 1976).
Main condition for peat: oxygen-poor moisture in which the rate of organic accumulation exceeds the rate of degradation.
Coal found in East USA in the Appalachian, Illinois, and Kansas Basins.
Coal deposits formed in Carboniferous Period (Pennsylvanian Period 320 to 286 MYA).
Predominant sequence of strata is many-layered cyclothems, caused by recurrent thrust loading and eustatic changes in sea level.
Farther west towards mid-continent
= more marine deposits and more eustatically controlled strata.
References (Make sure to have 'hanging indent' for this... i can't format it on this site)
Cengage, Gale, 2003, Pennsylvanian Period, World of Earth Science.,Ed. K. Lee Lerner and Brenda Wilmoth Lerner, 2006
DiMichele, William A., Tom L. Phillips, 1996, Climate change, plant extinctions and vegetational recovery during the Middle-Late Pennsylvanian Transition: the Case of tropical peat-forming environments in North America, Geological Society, London, Special Publications, v. 102; p. 201-221
Garcés, Blas L. Valero; Gierlowski-Kordesch, Elizabeth; Bragonier, William A.; 1996. Pennsylvanian continental cyclothem development: no evidence of direct climatic control in the Upper Freeport Formation (Allegheny Group) of Pennsylvania (northern Appalachian Basin), Sedimentary Geology. Elsevier Science B.V., pp. 305.
Klein, George; Willard, Debra A.; 1989. Origin of the Pennsylvanian coal-bearing cyclothems of North America, University of Illinois at Urbana-Champaign, Illinois 61801-2999.
Miall, Andrew D.,1997. The Geology of Stratigraphic Sequences, Springer-Verlag Berlin Heidelberg, New York, p.162.
Moore, Raymond C., 1964, Paleoecological Aspects of Kansas Pennsylvanian and Permian Cyclothems, Symposium on cyclic sedimentation: Kansas Geological Survey, Bulletin 169, pp. 287-380.
Nevins, Stuart E., 1976. The Origin of Coal, Institute for Creation Research, Dallax, TX. Weller, J. Marvin, 1930, Cyclical Sedimentation of the Pennsylvanian Period and its Significance, The Journal of Geology, Vol. 38, No. 2, pp. 97-135 .
Oct 31, 2009
Fastov's 'Relevant' Advice About Coal (10/26 class):
Coal is a metamorphic rock made of peat deposits.
Find where and why peat deposits form.
Why was peat there to start with.
Eastern coal tends to be higher grade than western coal.
There appear to be certain repetitive qualities in the coals (primarily the Michigan, Illinois, and Appalachian basins), why is that?
DON'T WORRY ABOUT STAGES OF COALS!
*Maps showing where coal deposits are and aren't in the US is a good idea*
What is the relationship between Michigan, Illinois, and Appalachian basins? ( ties in with previous bullet^^^)
What is the basin associated with the Appalachian Plateau (note i said basin above but its technically a plateau but has its own basin, at least that's what i got out of what was said)
What the particular geologic conditions as to why and how coal forms?
Position has to do with when and why the peat is accumulating, not how it will form.
Rhode Island and Ireland are closely related geologically and both have some of the richest coal currently forming in them today.
P.S. I'll gather more info on Michigan basin to help out and should be posted by the end of the night. Good luck Zoe.
More Notes & Advice from Fastovsky:
Why does too much water cause the coalification process to stop? - Plants are terrestrial so salt water, especially too much of it, kills the formation of plants. However with no or not enough water, plants can't grow.
When rivers get backed up, they flood and this can use swamp areas to develop. This concentration of water produces an anaerobic ("without air") environment under water that allows plant matter to form into coal. The water kills most of the bacteria so that the decay process is slowed (if the process is too fast, plants will completely decay before they are able to form coal).
Find pictures of Appalachian, Kansas, and Illinois sequences.
How long does is a single cyclothem?
What types of processes operate on this time scale?
What is the driving force behind a cyclothem?
Define cyclothem for each: Illinois, Kansas, Appalachian
How many cyclothems are there?
Illinois has sediment coming from a different source. What is that source?
Research the Kansas sequence and completely skip Michigan
Basins are zones of deposition.
sed. rocks fill up basins so long as there is "net aggregation". (not sure completely sure what he means. i think he's referring to how sediment rocks will collect in these locations and not continue to disperse even futher but will actually remain in the basin area until it becomes flat).
Why is coal found almost entirely in the Carboniferous period only? There is a small amount from the Cretacious, but almost all coal is Carboniferous.
Coal can form in other places, not just river planes and coastal swamps.
Coal can form in any location in which organic productivity exceeds the rate of decomposition.
What other types of places provide this environment?
Marine vs. Tectonic, or both?
Ideas for slides:
What is peat and how it forms (one slide)
(remove Where, When, Why part)
conditions needed to form coal, where can it form (1-2 slides)
also why is coal found almost entirely from carboniferous?
2, maybe 3 slides total for each location (Illinois, Kansas, Appalachian)
paleo-environments for each loc.
how each one formed for each loc.
provide a picture of a sequence for each one?
(should we skip slide 8?)
what are they? what drives them?
how long do they take?
how many are there? / what cyclothems are found in our locations?
Marine vs. Tectonic, or both? (i'm leaning towards both, but that's my personal opinion. either way, we should explain why we picked the one we end up choosing)
(remove slide 11, pangea was from the mesozoic era, which might be a bit too far off to represent the carboniferous coals even though they're close on the time scale)
also alter the conclusion page accordingly
"Past controversy about the tectonic or eustatic origin of Pennsylvanian cyclothems is resolved by regional basin-subsidence analysis, global paleoclimate, paleogeography, and plate-tectonic evolution. Differences between marine carbonate (Kansas-type) cyclothems of the northern midcontinent and nonmarine clastic (Appalachian-type) cyclothems of the eastern United States are controlled by laterally changing flexural deformation during plate accretion into a supercontinent, coupled with superposed glacial eustasy. Kansas-type cyclothems accumulated on a relatively stable platform affected only moderately by collision tectonics of North American margins; these cycles are eustatic, characterized by a periodicity comparable to Milankovitch orbital parameters. Appalachian-type cyclothems accumulated in response to episodic thrust loading during plate collisions that developed a series of flexurally deformed, wide and shallow, resurgent foreland basins. This resurgent foreland basin evolution during Paleozoic time increased crustal rigidity in the Appalachians, thus yoking the Appalachian and Illinois basins during Pennsylvanian time. With each thrust load, foreland basin deepening favored transgressive cyclothem facies, which changed to a regressive facies because sediment yield increased as denudation rates increased off uplifted orogens. Illinois-type cyclothems are intermediate between the two end-member processes of flexural tectonics and glacial eustasy characterizing Appalachian-type and Kansas-type cyclothems, respectively. Thus, the Pennsylvanian coal-bearing cyclothems of North America owe their origin to the remarkable coincidence of supercontinent development, concomitant glaciation and eustatic sea-level change, and associated episodic thrust loading and foreland basin subsidence of small magnitude on progressively more rigid crust."
: Klein, George; Willard, Debra A.; 1989. Origin of the Pennsylvanian coal-bearing cyclothems of North America, University of Illinois at Urbana-Champaign, Illinois 61801-2999.
"The occurrence of lacustrine carbonates in the Allegheny Group (upper Middle Pennsylvanian) continental cyclothems of the northern Appalachian Basin has been attributed to climatic alternation of wet (coal deposition) and dry (carbonate deposition) periods."
: Garcés, Blas L. Valero; Gierlowski-Kordesch, Elizabeth; Bragonier, William A.; 1996. Pennsylvanian continental cyclothem development: no evidence of direct climatic control in the Upper Freeport Formation (Allegheny Group) of Pennsylvania (northern Appalachian Basin), Sedimentary Geology. Elsevier Science B.V., pp. 305.
"Coal commonly occurs in a sequence of sedimentary strata called a
may have strata deposited in the following ascending order: sandstone, shale, limestone, underclay, coal, shale, limestone, shale. A
will normally be missing one or more of the component strata. In any one locality
commonly repeat tens of times with each cycle of deposition accumulated on a previous one. There are fifty successive cycles in Illinois and over a hundred in West Virginia."
: Nevins, Stuart E., 1976. The Origin of Coal, Institute for Creation Research, Dallax, TX.
What is a cyclothem?
eposits of a single sedimentary cycle of interrelated phases associated with a landward-and-seaward oscillation of the strandline. (
- strata belonging to a group of successive sedimentary cycles which exhibit regularity of occurrence in sequence, with each cyclothem marked by distinctive characters (
Miall, Andrew D.,1997. The Geology of Stratigraphic Sequences, Springer-Verlag Berlin Heidelberg, New York, p.162.
Why Were Coals Prominent in the Carboniferous?
During the Carboniferous period much of the North American continent and European continent were located close to the equator. This may have allowed for large expanses of swamp forests to develop in wetland areas.
According to another source, towards the end of the Carboniferous period temperatures became increasingly much more cool, averaging around 10º C:
"Interestingly, the last half of the Carboniferous Period witnessed periods of significant ice cap formation over polar landmasses-- particularly in the southern hemisphere. Alternating cool and warm periods during the ensuing Carboniferous
coincided with cycles of glacier expansion and retreat. Coastlines fluctuated, caused by a combination of both
local basin subsidence
worldwide sea level changes
. In West Virginia a complex system of meandering river deltas supported vast
that left repeating stratigraphic levels of peat bogs that later became coal, separated by layers of fluvial rocks like sandstone and shale when the deltas were building, and marine rocks like black shales and limestones when rising seas drowned coastlands." (
No clue if this is relevant but I also found this image showing the CO2 levels over time.
I. What distinguishes a coal deposit from the surrounding rocks?
(what is coal?)
What is Coal?
- Coal is a black or brownish black, solid, combustible rock (sedimentary) containing less than 40% non-combustible inorganic components formed by the accumulation, decomposition and compaction of plant materials under long-acting geological processes.
What are the uses of Coal?
- Coal is used mainly in the generation of electricity and manufacture of cement. Power plants burn coal to produce energy in the form of heat for changing water to steam. The steam turns the blades of a turbine which spins a generator to produce electricity. About half of the electricity in the United States comes from burning coal. We use electricity every day in many ways. Some examples of ways that we use electricity are heating, cooling and lighting our homes and cooking and refrigerating our food. By-products of coal are also used by companies to make items such as steel, cosmetics, and tar.
II. How do coals form? What are the different types? Ages? Locations of typical deposition?
Coal normally occurs in rock layers or veins, called coal beds.
Formation Process (called
The formation of coal begins with the formation of several layers of plant remains that accumulate over the years. These plant remains must be protected from chemical breakdown and oxidization within the environment.
Then it becomes trapped in peat bogs which over time become buried by sediments, causing immense pressure and thus metamorphism.
This process takes millions of years.
Coal is formed when peat is altered physically and chemically. This process is called "coalification." During coalification, peat undergoes several changes as a result of bacterial decay, compaction, heat and time. Peat deposits are quite varied and contain everything from pristine plant parts (roots, bark, spores, etc.) to decayed plants, decay products and even charcoal if the peat caught fire during accumulation. Peat deposits typically form in a waterlogged environment where plant debris accumulated; peat bogs and peat swamps are examples. In such an environment, the accumulation of plant debris exceeds the rate of bacterial decay of the debris. The bacterial decay rate is reduced because the available oxygen in organic-rich water is completely used up by the decaying process. Anaerobic (without oxygen) decay is much slower than aerobic decay.
For the peat to become coal, it must be buried by sediment. Burial compacts the peat and, consequently, much water is squeezed out during the first stages of burial. Continued burial and the addition of heat and time cause the complex hydrocarbon compounds in the peat to break down and alter in a variety of ways. The gaseous alteration products (methane is one) are typically expelled from the deposit, and the deposit becomes more and more carbon-rich as the other elements disperse. The stages of this trend proceed from plant debris through peat, lignite, sub-bituminous coal, bituminous coal, anthracite coal to graphite (a pure carbon mineral).
Because of the amount of squeezing and water loss that accompanies the compaction of peat after burial, it is estimated that it took 10 vertical feet of original peat material to produce 1 vertical foot of bituminous coal in eastern and western Kentucky. The peat-to-coal ratio is variable and dependent on the original type of peat the coal came from and the rank of the coal.
Types of Coal
We use the term "coal" to describe a variety of fossilized plant materials, but no two coals are exactly alike. Heating value, ash melting temperature, sulfur and other impurities, mechanical strength, and many other chemical and physical properties must be considered when matching specific coals to a particular application.
Coal is classified into four general categories, or "ranks." They range from lignite through sub-bituminous and bituminous to anthracite, reflecting the progressive response of individual deposits of coal to increasing heat and pressure. The carbon content of coal supplies most of its heating value, but other factors also influence the amount of energy it contains per unit of weight. (The amount of energy in coal is expressed in British thermal units per pound. A BTU is the amount of heat required to raise the temperature of one pound of water one degree Fahrenheit.)
About 90 percent of the coal in this country falls in the bituminous and sub-bituminous categories, which rank below anthracite and, for the most part, contain less energy per unit of weight. Bituminous coal predominates in the Eastern and Mid-continent coal fields, while sub-bituminous coal is generally found in the Western states and Alaska.
Lignite ranks the lowest and is the youngest of the coals. Most lignite is mined in Texas, but large deposits also are found in Montana, North Dakota, and some Gulf Coast states.
Anthracite is coal with the highest carbon content, between 86 and 98 percent, and a heat value of nearly 15,000 BTUs-per-pound. Most frequently associated with home heating, anthracite is a very small segment of the U.S. coal market. There are 7.3 billion tons of anthracite reserves in the United States,
found mostly in 11 northeastern counties in Pennsylvania.
The most plentiful form of coal in the United States, bituminous coal is used primarily to generate electricity and make coke for the steel industry. The fastest growing market for coal, though still a small one, is supplying heat for industrial processes. Bituminous coal has a carbon content ranging from 45 to 86 percent carbon and a heat value of 10,500 to 15,500 BTUs-per-pound.
Ranking below bituminous is sub-bituminous coal with 35-45 percent carbon content and a heat value between 8,300 and 13,000 BTUs-per-pound. Reserves are located mainly in a half-dozen Western states and Alaska. Although its heat value is lower, this coal generally has a lower sulfur content than other types, which makes it attractive for use because it is cleaner burning.
Lignite is a geologically young coal which has the lowest carbon content, 25-35 percent, and a heat value ranging between 4,000 and 8,300 BTUs-per-pound. Sometimes called brown coal, it is mainly used for electric power generation
III. Where are the coals in the East US? (east of mississippi). Why are they where they are? Why are the specific types there?
US Coal Regions:
(click to view full size - opens in new window)
external image Us_coal_regions_1996_legend.png
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