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Articles 241 - 270 of 473
Full-Text Articles in Geology
The Relation Of Radium-226 And 228 To The Groundwater Geochemistry Of Carbon, Sulfur, And Chlorine Near Michigan's Saginaw Bay, Ray Milejczak
The Relation Of Radium-226 And 228 To The Groundwater Geochemistry Of Carbon, Sulfur, And Chlorine Near Michigan's Saginaw Bay, Ray Milejczak
Masters Theses
The Michigan Department of Public Health (MDPH) sampled 149 residential wells producing from glacial drift and Saginaw Formation aquifers in Bay, Midland, Saginaw, and Tuscola counties in 1987. These wells were analyzed for 226Ra, 228Ra and general chemistry. Of the 149 samples, 50 exceeded the USEPA MCL of 5 pCi/L or greater for combined 226Ra + 228Ra activities. A geochemical model (WATEQF, Plummer et al., 1976) was used to determine activity coefficients, activities, ionic strength, and mineral saturation. The radium isotopes were statistically analyzed with respect to the chemical data from MDPH and the geochemical model …
Wetland Study Of Southeastern Portage Township, Kalamazoo County, Michigan, Kevin M. Walsh
Wetland Study Of Southeastern Portage Township, Kalamazoo County, Michigan, Kevin M. Walsh
Masters Theses
Under the Clean Water Act, Congress passed legislation to maintain and restore the chemical, physical, and biological integrity of the water of the United States. The objective of this study is to determine if the wooded area located in Upjohn Company's Property in southeastern Portage Township, Portage, Michigan falls under the classification of a wetland.
This objective has been pursued through an examination of the hydrology of the area, the soil characteristics of the area, and the vegetation types and characteristics of the area. These parameters have been utilized following the guidelines outlined in the "Corps of Engineers Wetland Delineation …
Geology And Petrochemistry Of The Mount Chase Massive Sulfide Prospect, Penobscot County, Maine, Michael V. Scully
Geology And Petrochemistry Of The Mount Chase Massive Sulfide Prospect, Penobscot County, Maine, Michael V. Scully
Masters Theses
"The Mount Chase massive sulfide prospect of northern Penobscot County, Maine was discovered in 1979 by Getty Mining Company. The deposit occurs within a sequence of lower paleozoic metavolcanic and metasedimentary rocks. The footwall units consist of rhyolitic flows, quartz-feldspar crystal tuff, and altered tuffaceous volcanic breccias. These rocks lie unconformably upon intensely folded sediments which are tentatively correlated with the Grand Pitch Formation of probable Cambrian age. The footwall volcanoclastic rocks exhibit a narrow zone of intense chloritic alteration immediately below the massive sulfide horizon, and a broader zone of sericitic alteration below that. A zone of stringer mineralization …
An Investigation Of A Soil Gas Sampling Technique And Its Applicability For Detecting Gaseous Pce And Tca Over An Unconfined Granular Aquifer, Timothy J. Mayotte
An Investigation Of A Soil Gas Sampling Technique And Its Applicability For Detecting Gaseous Pce And Tca Over An Unconfined Granular Aquifer, Timothy J. Mayotte
Masters Theses
A soil gas sampling and analytical technique was investigated to evaluate its ability and versatility for detecting chlorinated hydrocarbons in unconfined aquifers. The technique was used successfully to delineate plumes of perchloroethene (PCE), and 1,1,1-trichloroethane (TCA) contamination present in the vadose zone, and at the water table of an unconfined sand and gravel aquifer. Soil gas samples were obtained by concentrating PCE and TCA vapors diffusing from these sources onto a sorbent material. The samples were analyzed by gas chromatography. The data from the analysis of these samples were used to provide an initial estimate of the source areas, and …
Fission-Track Geochronology And Geothermometry Of Late Cretaceous-Early Tertiary Epizonal Plutons, In And Adjacent To The Lombard Thrust Fault, Southwestern Montana, Jean Talanda
Masters Theses
Thrusting occurred in the central portion of the central Montana salient where the timing of movements is somewhat obscured by the multiple deformations from Archean time to the present. The relationship of this thrusting to the associated plutons has not been established in every case. Fission-track geochronology was employed in dating several plutons associated with the Lombard thrust fault, consequently, defining a time range in which movement along the thrust occured.
Seven plutons with known structural relationships to the Lombard thrust have ages which suggest that movement along the fault occurred 73.2 +/- 6.7 Ma. Fission-track length distributions suggest that …
A Trace Element Geochemical Analysis Of The Lake Ellen Kimberlite, Crystal Falls, Michigan, U.S.A., Michelle Ellen Fults
A Trace Element Geochemical Analysis Of The Lake Ellen Kimberlite, Crystal Falls, Michigan, U.S.A., Michelle Ellen Fults
Masters Theses
The Lake Ellen kimberlite located in the Upper Peninsula of Michigan represents a possible bedrock source for the diamonds found in the glacial deposits around the Great Lakes. The purpose of this research was to undertake a geochemical analysis in order to better understand the evolution of the kimberlite body and to elucidate on the garnet xenolith paragenesis.
Both instrumental neutron activation analysis (INAA) and scanning electron microscope analysis (SEM) were utilized in this research. The INAA revealed that with respect to other types of upper mantle rocks, the Lake Ellen kimberlite is enriched in both the light rare earth …
Deposition, Diagenesis, And Porosity Development Of The Middle Devonian, Lucas Formation In The West Branch Oil Field, Ogemaw County, Michigan, Scott Gregory Park
Deposition, Diagenesis, And Porosity Development Of The Middle Devonian, Lucas Formation In The West Branch Oil Field, Ogemaw County, Michigan, Scott Gregory Park
Masters Theses
The Lucas Formation in the West Branch Oil Field contains over 1000 feet of carbonates and evaporites deposited in restricted marine environments. Deposition ranged from a tidal flat environment (Richfield Member) to subaqueous basin central type deposition (Iutzi and Horner Members).
Early diagenesis of the Lucas Formation carbonates included dolomitization and related porosity development in certain depositional facies where physiochemical conditions were favorable. Significant porosity and permeability reduction occurred during burial resulting from anhydrite, celestite, and halite cementation. Calcite pseudopar and microspar (a neomorphic product) also reduced porosity.
Hydrocarbon production from the Lucas Formation in the West Branch Field is …
Possible Role Of Petroliferous Materials In Sulfide Precipitation At The Frank R. Millikan Mine, Southeast Missouri, Clark Alan Niewendorp
Possible Role Of Petroliferous Materials In Sulfide Precipitation At The Frank R. Millikan Mine, Southeast Missouri, Clark Alan Niewendorp
Masters Theses
The Millikan Mine's ore body contains ubiquitous amounts of petroliferous materials occurring as blebs, coal-like pods and veinlets, and seeps coating mine stope walls. Emplacement of hydrocarbons into the ore occurred before the final episode of mineralization ceased, based on growth of dendritic galena in some coal-like bitumen and other paragenetic relationships. Growth of dendritic galena in a hydrocarbon substance suggests that hydrocarbons provided sulfur for galena mineralization by either abiogenetic reduction of sulfate or thermochemical evolution of organic sulfur. Texturally, it also suggests that the presence of hydrocarbons may have been responsible for some zones of rapid precipitate mineralization. …
A Thermodynamic Study Of The Zeolite Stilbite, David Adams Howell
A Thermodynamic Study Of The Zeolite Stilbite, David Adams Howell
Masters Theses
Stilbite is a calcium-rich zeolite found in low-grade metamorphic and hydrothermally altered environments. In this study, measurements of the enthalpy of formation at 298.15 K, heat capacity from 5 to 350 K, and enthalpy increments horn 350 to 500 K were performed on a specimen of stilbite characterized by electron microprobe analysis. The actual formula of the stilbite is: Ca1.019Na0.136K0.006Al2.180Si6.820O16 . 7.33H2O. Evaluation of the thermodynamic properties for stilbite at T = 298.15 K produced the following values: ΔrHOm(T)= -11034.6+6.6 kJ . mol …
Nitrate Pollution Of Ground Water In Glacial Sediments Underlying A Fertigated Site In Kalamazoo County, Michigan, Michael Wireman
Nitrate Pollution Of Ground Water In Glacial Sediments Underlying A Fertigated Site In Kalamazoo County, Michigan, Michael Wireman
Masters Theses
In the central part of Schoolcraft Township high yield corn crops are successfully grown on soils developed on permeable outwash deposits. The high yields are made possible with the utilization of modern irrigation techniques and regular application of nitrogen fertilizer.
Excess nitrogen which moves past the root zone is easily converted to nitrate and leached to the shallow ground water. Water quality data from 103 ground-water samples in the vicinity of a 160-acre corn field in Section 11 clearly indicate that nitrate concentrations in the ground water beneath the field and beneath the area immediately downgradient from the field are …
The Effect Of Well Efficiency On In-Situ Permeability Test Results, Scott T. Dennis
The Effect Of Well Efficiency On In-Situ Permeability Test Results, Scott T. Dennis
Masters Theses
The purpose of this study was to determine what effect well efficiency has upon the results of in-situ permeability tests.
Several in-situ permeability tests were performed on wells during various stages of their development. The well efficiency was determined each time an in-situ test was performed. An accurate value of permeability was determined by performing local aquifer pumping tests. The accuracy of the results of the in-situ tests with respect to the aquifer pump test results were then compared to the efficiency of the well at the time of the test.
Test results showed that a linear relationship exists between …
Structural Geology And Geothermal Investigation Of The White Sulphur Springs Area, Montana, William G. Gierke
Structural Geology And Geothermal Investigation Of The White Sulphur Springs Area, Montana, William G. Gierke
Masters Theses
Sevier thrusting in the White Sulphur Springs area was associated with left-lateral movement along the Lewis and Clark line . During Middle Miocene time, the Lewis and Clark line exhibited right-lateral movement, forming extensional features that either truncated Sevier structures or followed preexisting Sevier zones of weakness.
The Smith River Valley is a pull-apart basin that is filled with Tertiary volcanic ash and clay-rich sediments that are thermally nonconductive relative to surrounding rocks.
Hydrothermal activity in the area is associated with a structurally controlled circulation system accompanied by a high thermal gradient. Thermal discharge is constrained along the north-trending White …
Lithofacies Analysis Of The Lamotte Sandstone In South Central Missouri, Michael Gerard Kraenzle
Lithofacies Analysis Of The Lamotte Sandstone In South Central Missouri, Michael Gerard Kraenzle
Masters Theses
"Based on the analysis of thirty-one cores obtained from the Missouri Department of Natural Resources in Rolla, the upper Cambrian Lamotte Sandstone in South Central Missouri has been divided into six sedimentary facies ranging from alluvial fan and braided stream to open marine.
The Lamotte Sandstone is the basal Cambrian sandstone found throughout most of the state of Missouri. It directly overlies late Precambrian (1.4 to 1.5 billion year old) granites and metasediments. The Lamotte and overlying Bonneterre Formations are generally considered to have been deposited by a transgression which occurred during the Late Cambrian Period (Croixian Epoch).
The Lamotte …
A Gravity And Magnetic Study Of The Crooked Creek Cryptoexplosion Structure, Crawford County, Missouri, Charles Edward Woodbury
A Gravity And Magnetic Study Of The Crooked Creek Cryptoexplosion Structure, Crawford County, Missouri, Charles Edward Woodbury
Masters Theses
"The pre-Pennsylvanian structure at Crooked Creek consists of a complex, vertically faulted ring of Cambrian and Ordovician sediments with a central uplifted core. The center of the structure is strongly deformed and contains shatter cones, brecciation, and other signs of extreme shock.
A magnetic low over the center of the structure suggests that igneous material was not involved in the formation of the structure, and this is corroborated by core analysis. Gravity data indicates several small gravity lows, possibly associated with areas of brecciation, circling the flanks of the structure. As in the magnetic data, there is no indication that …
A Paleoenvironmental Study Of The Salem Limestone In The Vicinity Of St. Louis, Missouri, Douglas J. Van Brunt
A Paleoenvironmental Study Of The Salem Limestone In The Vicinity Of St. Louis, Missouri, Douglas J. Van Brunt
Masters Theses
“The Salem Limestone (Meramecian) of Mississippian age in the vicinity of St. Louis, Missouri is composed of a variable sequence of limestones deposited in shallow waters adjacent to scattered positive elements. This unit varies in thickness from zero up to 160 feet.
A medium to coarse-grained calcarenite is the dominant rock-type of the thesis area and is most abundant in the central and southwest regions. Stratigraphic sections in the northern region are more dolomitic, increasingly brecciated, and contains numerous secondary features. The southeast region is thinly bedded and composed of greater amounts of micrite formed by algal activity or direct …
A Petrographic Investigation Of The Rhythmically Bedded Upper Fayetteville Formation (Mississippian) In Northern Arkansas, Edith Ann Starbuck
A Petrographic Investigation Of The Rhythmically Bedded Upper Fayetteville Formation (Mississippian) In Northern Arkansas, Edith Ann Starbuck
Masters Theses
"The upper Mississippian Fayetteville Formation in northern Arkansas is primarily a calcareous black shale, but in some localities the upper one third to one half of the formation is made up of alternating black shales and limestones. Comparable lithologies have been suggested by some (Hallam, Ricken, Kent, and Sujkowski) to have been created by the diagenetic segregation of carbonate from calcareous shale.
Petrographic thin section analysis reveals that the lowest limestone beds of the rhythmic upper Fayetteville are made up almost entirely of microspar and all fossil material is recrystallized, even to the point of obliteration in some cases. The …
A Hydrogeologic Investigation Of The Balkema Wetland, Daniel V. Fronczek
A Hydrogeologic Investigation Of The Balkema Wetland, Daniel V. Fronczek
Masters Theses
The Balkema wetland, located In southwestern Kalamazoo County, Michigan, represents complex biological and hydrologic Interaction between surface water and a two-aquifer hydrologic system. Situated on the southeastern flank of the Kalamazoo moraine, the glacial geology of the area plays a key role in the understanding of the hydrogeologic function of the wetland. A two-aquifer system, an upper unconfined, and a lower confined, Interact In the vicin ity of the wetland where the c la y /till aqulclude dividing the two systems 1s absent. Various parameters, both hydrologic and geochemical, were measured In the study area, Including specific conductance values of …
A Structural Investigation Of A Basement-Involved Thrust System In Southern Sphinx Mountain Quadrangle (Madison Range) Southwestern Montana, Jeffrey Scott Brown
A Structural Investigation Of A Basement-Involved Thrust System In Southern Sphinx Mountain Quadrangle (Madison Range) Southwestern Montana, Jeffrey Scott Brown
Masters Theses
The Madison Range is the eastern limb of the Laramide Rocky Mountain foreland Madison-Gravelly Arch. The main segment of the Madison thrust system in the map area is the basement-involved Scarface thrust which dips westward, trends north-northwest, and places Archean rocks onto an overturned footwall of Cambrian through Cretaceous rocks. Foliation of Archean rocks in the footwall is folded with overlying sedimentary rocks.
The Shedhorn Mountain thrust splays from the Scarface thrust. It is exposed north and south of the Shedhorn Mountain anticline, but is blind beneath it. The Taylor fault, an east-dipping back thrust, is inferred to be associated …
Stratigraphic And Sedimentologic Analysis Of The Middle Devonian Filer Sandstone, John Charles Rodwan
Stratigraphic And Sedimentologic Analysis Of The Middle Devonian Filer Sandstone, John Charles Rodwan
Masters Theses
The Filer Sandstone, a multistory assemblage o£ lenticular sand bodies, is a member of the Middle Devonian Amherstburg Formation of the Detroit River Group in the subsurface of the western and central portion of the Michigan Basin. It is distinguished from the reworked eolian and nearshore marine sand facies of the underlying Sylvania Sandstone by recognition of its barrier island facies relationships and stratigraphic position within enclosing carbonates unique to the Amherstburg Formation. Lithologically, the Filer ranges from a fine-grained, carbonate-cemented, supermature quartzarenite at its upper shoreface facies, to a texturally-inverted sandy carbonate at its lagoonal facies. Facies distribution was …
Petrography, Diagenetic History, And Development Of Porosity In The Richfield Member Of The Lower Middle Devonian Lucas Formation, Northeast Isabella County, Central Michigan Basin, Kevin James Sullivan
Petrography, Diagenetic History, And Development Of Porosity In The Richfield Member Of The Lower Middle Devonian Lucas Formation, Northeast Isabella County, Central Michigan Basin, Kevin James Sullivan
Masters Theses
The Richfield Member of the lower Middle Devonian Lucas Formation is represented in the subsurface of northeast Isabella County, Michigan as a 180-foot-thick sequence of Interbedded limestone, dolomite and anhydrite. Richfield lithofacies within the study area reflect deposition in a complex patchwork mosaic of evaporative supratidal, in tertid al, shoal, and subtidal environments.
The present variations in Richfield porosities were caused almost entirely by post-depositlonal diagenetic changes. The carbonate units have undergone pervasive dolomltlzation of mud matrix, leaching of allochems, and extensive anhydrite void -fillin g . The best porosity developments are associated with partial to complete dolomitizatlon of the …
An Evaluation Of The Effectiveness Of Bentonite As A Soil Additive For The Cover Material On The Kl Avenue Sanitary Landfill, Kalamazoo, Michigan, Neal J. Carey
Masters Theses
A principle objective of using bentonite as a soil additive is to reduce the permeability of a cover material, thus, inhibiting the infiltration of surface waters at landfill sites.
Twenty-two cores of the KL landfill were taken to obtain in-situ soil columns for testing. Coefficients of permeability were calculated for each soil column using the falling-head permeameter. Mechanical and hydrometer analyses were used for the grain size analysis. The methylene-blue test was employed to determine the actual percentages of bentonite present in each soil column. X-ray diffraction work was done on the clay fraction of each soil column to verify …
The Provenance Of The Jacobsville Formation Of The Upper Peninsula Of Michigan Through A Petrographic Study, David Walter Lindsay
The Provenance Of The Jacobsville Formation Of The Upper Peninsula Of Michigan Through A Petrographic Study, David Walter Lindsay
Masters Theses
The Upper Keweenawan Jacobsville Formation source areas were mixed source terranes with dominant terrane types changing regionally in relative abundances of sediment contribution. Dominant source terranes were older sediments, including a weathered soil zone, Upper Keweenawan Freda Sandstone and other recycled sandstones; plutonic Precambrian basement rocks;. Middle Keweenawan Portage Lake Volcanics; and the chlorite to staurolite grade metamorphic rocks and iron ranges of Michigan’s upper peninsula.
Depositional environments of the formation's four facies types range from fluvial to deltaic/lacustrine. Sediments were in transport for a short distance, resulting in grain freshness and angularity, moderate sorting and preservation of unstable sediments. …
Facies Development And Porosity Relationships In The Dundee Limestone Of Gladwin County, Michigan, Eric Lee Montgomery
Facies Development And Porosity Relationships In The Dundee Limestone Of Gladwin County, Michigan, Eric Lee Montgomery
Masters Theses
The Devonian of the Michigan Basin was a time of transgressive seas and extensive carbonate deposition including coral and stromatoporoid buildups. Deposited during the Middle Devonian, the Dundee Limestone represents deposition in subtidal, intertidal, and restricted environments. The Buckeye Oil Field, located in south-central Gladwin County, is a combined stratigraphic and structural carbonate trap which produces from a series of intertonguing patch reefs, fringing sand bodies, and "intertidal island" fenestral zones. The major reef building organisms include stromatoporoids, corals, calcareous algae, brachiopods, and crinoids, with the stromatoporoids providing the major framework. The patch reef facies is composed of massive stromatoporoid …
Geology Of The Escalante District, Iron County, Utah, James William Biehl
Geology Of The Escalante District, Iron County, Utah, James William Biehl
Masters Theses
"The Escalante Silver District, Iron County, Utah, occupies a group of low hills extending to the Escalante Desert from the Black Hills to the south. Tertiary volcanics serve as host rocks for silver bearing quartz veins. Five map units, with a total of 12 members are recognized. X-ray fluorescence and field mapping enabled differentiation of the units, while thin section analysis enabled characterization of the members. The map units formed in three episodes. The oldest is extrusive doming of distinctive older lava and breccia flows. The middle group is made up of tectontic breccias, sillar-like lava flows, and volcaniclastic sediments …
Lithofacies And Geochemistry Of Interreef Carbonates, Middle Silurian, Michigan Basin, Eric N. Porcher
Lithofacies And Geochemistry Of Interreef Carbonates, Middle Silurian, Michigan Basin, Eric N. Porcher
Masters Theses
The Niagara Group of the Michigan Basin is composed of reef, interreef, and basinal carbonates. The Niagara Group interreef has herein been divided into several litho facies: algal-laminated dolomicrite, bioturbated dolomicrite, intraclastic dolomicrite, wispy-laminated dolomicrite, crinoidal micrite, and nodular micrite. These interreef carbonates show a shallowing upward sequence.
The geochemistry of the Niagara Group interreef was examined in an attempt to delineate any geochemical gradients with respect to reefs. The geochemistry of the inter reef was determined by Particle Induced X-Ray Emission (PIXE) analysis. No significant geochemical gradients were found to be associated with reefs. Reasons for this may include: …
The Response Of The Kentucky River Drainage Basin To A Lowering Of Base Level Control, David B. Warwick
The Response Of The Kentucky River Drainage Basin To A Lowering Of Base Level Control, David B. Warwick
Masters Theses
The Kentucky River has responded to a lowering of base level control by: 1) deepening the course of its channel; 2) cutting off meanders as incision proceeded; 3) developing knickpoints on tributaries; 4) widening its valley; and 5) dissecting the upland surface.
Field work involved surveying streams to obtain profiles. Twenty streams covering 125 miles of river from Carrollton to Camp Nelson, Kentucky were surveyed. Knickpoints were defined from these profiles. Data from stream profiles showed knickpoint distances decreasing with increasing distance up river. Map work involved obtaining data for hypsometric curves. Hypsometric integrals were determined from these curves. Data …
Subsurface Stratigrapy And Sedimentologic Control On The Productive Middle Devonian Age Richfield Member Of The Lucas Formation In The Michigan Basin, Sukru Nail Apak
Subsurface Stratigrapy And Sedimentologic Control On The Productive Middle Devonian Age Richfield Member Of The Lucas Formation In The Michigan Basin, Sukru Nail Apak
Masters Theses
The depositional system of the Middle Devonian Richfield Member of Lucas Formation in the Michigan Basin was delineated using well logs, cores, drillers' records, and the literature. The Richfield Member was deposited in Sabkha and lagoonal environments characterized by cycles of anhydrite, dolomite, and limestone. Seven significant productive dolomitic zones, interbedded with anhydrite and limestone can be correlated throughout the study area. These zones change laterally to anhydrite towards the west flank and to dense limestone towards the east flank of the basin. Post-depositional diagenetic history of the Richfield was established with the aid of scanning electron microscopy and electron …
A Seismic Study Of An Impact Feature In Cass County, Michigan, Mancheol Suh
A Seismic Study Of An Impact Feature In Cass County, Michigan, Mancheol Suh
Masters Theses
A geophysical investigation, including a seismic study, of the subsurface structure of the Calvin-28 oil field, Cass County, Michigan, indicates that the structure's origin may be related to an impact event. The structural closures in the time structure maps and drilling results both show a central uplift. The fault system in the Trempealeau Formation shows a structure similar to other proven astroblemes. Undisturbed layers just beneath the central uplift also provide evidence of an impact structure. The result of mathematical modeling of the central uplift under the assumption that the structure is an impact structure corresponds well with the drilling …
A Gravity Investigation Of Mountain Flank Thrusting And Normal Faulting, Madison And Tobacco Root Ranges, Montana, Stephen Thomas Wigger
A Gravity Investigation Of Mountain Flank Thrusting And Normal Faulting, Madison And Tobacco Root Ranges, Montana, Stephen Thomas Wigger
Masters Theses
Gravity modeling of west-dipping, Laramide mountain flank thrusts which involve Archean metamorphic rocks in the western Tobacco Root and northern Madison Ranges supports the idea that these thrusts are gently dipping.
The thrusts provided a favorable location for normal faulting during Neogene extension. The Neogene faults on the eastern portions of the Madison and Jefferson Basins are interpreted to be listric, and merge with the Laramide thrusts. Basin development occurred along a series of such faults, which dropped hanging wall blocks of the thrust sheets to progressively greater depths. The maximum depth of the Madison basin, near Ennis, was found …
Carbonate Facies Of The Kimmswick Limestone (Trenton/Galena) In Southwestern Illinois : Their Relations As Oil Reservoirs And Traps, Gregory A. Crews
Carbonate Facies Of The Kimmswick Limestone (Trenton/Galena) In Southwestern Illinois : Their Relations As Oil Reservoirs And Traps, Gregory A. Crews
Masters Theses
"Four potentially productive oil horizons have been identified in the Kimmswick Limestone (Trenton/Galena), Ordovician of southwestern Illinois. Four non-porous caprock zones and four porous horizons were identified and informally named after corresponding members of the Dunleith Formation (Illinois State Geological Survey classification). The porous horizons generally consist of coarse-grained, fossiliferous limestone, which is overlain by finer grained, spar-cemented, impermeable limestone.
In order of production potential, the horizons are the upper Moredock, lower Moredock, Beecher-St. James (lowermost stratigraphic unit), and New London (uppermost stratigraphic unit). Porosity in the upper Moredock horizon is relatively consistent throughout the study area, as determined by …