MRCSP Phase I Geologic Characterization Report - Midwest ...

126 CHARACTERIZATION OF GEOLOGIC SEQUESTRATION OPPORTUNITIES IN THE MRCSP REGION
15. PENNSYLVANIAN COAL BEDS IN THE APPALACHIAN BASIN
Coal beds of late Carboniferous-age occur in the Appalachian
basin portion of the MRCSP study area. The Appalachian basin,
one of the largest Pennsylvanian-age coal-producing regions in the
world, currently contains the second, third, and fourth leading coalproducing
states in the United States—West Virginia, Kentucky,
and Pennsylvania, respectively (EIA, 2005). The greater northern
Appalachian basin contains a series of smaller, anthracite-bearing
synclinal basins in eastern Pennsylvania, but these areas are not
included in this report.
STRATIGRAPHY
Coal beds considered potential targets for geologic CO 2 sequestration
occur in the Pennsylvanian Subsystem of the Appalachian
basin and range from early to late Pennsylvanian in age (Figure 5).
Within the MRCSP study area, portions of two sub-basins or depocenters
of Pennsylvanian-age occur, the northern Appalachian and
central Appalachian basins (Figure A15-1). The boundary between
these two sub-basins is approximately the southern limit of the outcrop
belt of the Conemaugh Group (Figure 5; see also Figure A15-1)
preserved in the Appalachian basin; this boundary also delineates
the division between the northern and southern coal fields of West
Virginia. Regional lithologic variations between the northern and
central Appalachian basins result in a variety of stratigraphic terms
applied within individual states of the partnership in order to divide
and define this large stratigraphic interval.
Pennsylvanian-age rocks in Ohio, Pennsylvania, Maryland, and
the northern coal fields of West Virginia are divided, in ascending
stratigraphic order, into the Pottsville, Allegheny, Conemaugh, and
Monongahela Groups (Figure 5). In the southern coal field of West
Virginia, changes in lithologic attributes and preservation of thicker
Lower and Middle Pennsylvanian strata result in the introduction of
the terms Pocahontas, New River, and Kanawha Formations. The
Kanawha and the upper part of the New River Formations are considered
lateral equivalents to the Pottsville Group. The lower part of
the New River and all of the Pocahontas are restricted to the southern
coal fields of West Virginia; also, the Pocahontas Formation is
older than, and does not correlate to, any known Pennsylvanian-age
rocks in other MRCSP states in the Appalachian basin.
In Kentucky, the stratigraphic interval equivalent to the Pottsville
and Allegheny Groups and the New River and Kanawha Formations
is known as the Breathitt Group. Chesnut (1992) proposed
a regional stratigraphic nomenclature for the central Appalachian
basin that divides the Breathitt Group into eight coal-bearing and
four quartzose-sandstone dominated formations; however, to date,
this nomenclature has been formalized only in Kentucky.
The Pennsylvanian- and Permian-age Dunkard Group, a unit
containing a few mostly thin coals of limited extent, overlies the
Monongahela Group in portions of Pennsylvania, Ohio, and West
Virginia. However, this unit lacks coal beds of adequate thickness
and/or depths for CO 2 sequestration consideration.
ORIGIN OF NAMES, TYPE SECTIONS,
SIGNIFICANT STUDIES
Rice and others (1994) summarize much of the stratigraphic nomenclature
used for coal-bearing rocks in the study area. Type or
reference sections are located where each unit was named.
Pottsville Group—Named for exposures at Pottsville Gap, Pennsylvania.
Allegheny Group—Named for exposures in the Allegheny River
valley of Pennsylvania.
Conemaugh Group—Named for exposures along the Conemaugh
River, Pennsylvania.
Monongahela Group—Named for exposures along the Monongahela
River, Pennsylvania.
Breathitt Group—Named for exposures in Breathitt County, Kentucky.
Kanawha Formation—Named for exposures along the Kanawha
River, West Virginia.
New River Formation—Named for exposures in New River Gorge,
West Virginia.
Pocahontas Formation—Named for exposures at Pocahontas, Virginia.
Geologic investigations of Pennsylvanian-age rocks have occurred
in the Appalachian basin since the 1830s. By the late 19 th
century, the economic significance of the coals in this interval stimulated
a wide array of regional and local studies on the economics,
stratigraphy, depositional history, and various other geologic disciplines
that continues today. Hence, a multitude of investigations on
specific attributes of Pennsylvanian-age rocks, as well as regional
summaries within each MRCSP state, have been presented in federal
and state geological survey publications. Moreover, numerous
special papers, field trip guidebooks, trade journal articles, and miscellaneous
reports by various geological societies, organizations,
and academia have, over the past 50 years or so, been published on
the region. A few notable examples of these types of publications include
U.S. Geological Survey Professional Papers 853 (McKee and
Crosby, 1975) and 1110-A-L (for example, see Collins, 1979), West
Virginia Geological Survey Volume 22 (Cross and Schemel, 1956),
Kentucky Geological Survey Series XI Bulletin 3 (Chesnut, 1992),
a collection of papers by the Carolina Coal Group (Ferm and Horne,
1979), and numerous regional guidebooks prepared for the meetings
of the 9 th International Congress of Carboniferous Stratigraphy and
Geology, the 28 th International Geological Congress, and the 1961,
1981, and 1992 Geological Society of America national meetings.
Additional references on the specific geologic framework within
each MRCSP state can be obtained from the geological surveys of
individual partnership states.
Thickness and chemical data on specific coal beds are available
through the National Coal Resource Database system (NCRDS) of
the U.S. Geological Survey or from each state geological survey.
The U.S. Geological Survey also has published a series of regional
coal maps and databases for several of the economically significant
coal beds in the region (Appalachian Basin Resource Assessment
Team, 2002). In addition, maps of most known, abandoned, underground
coal-mines are available from either federal or state agencies
for several of the partnership states.
NATURE OF LOWER AND UPPER CONTACTS
A significant geologic disconformity occurs in the Appalachian
basin between the top of the Mississippian Subsystem and the base
of the Pennsylvanian Subsystem in all but southern West Virginia;
there, continuous deposition occurred and Mississippian rocks