Geology Commons^™

Lithology And Depositional Environments Of A Portion Of The Clays Ferry Formation (Middle And Upper Ordovician) Exposed At Silver Creek, Madison County, Kentucky, Autumn Murray, Walter S. Borowski

EKU Faculty and Staff Scholarship

We measure, describe, and interpret a carbonate stratigraphic section within the Clays Ferry Formation (Middle and Upper Ordovician) cropping out in Madison County, Kentucky (USGS Kirksville 7.5” quadrangle). Outcrops are exposed within the bed of Silver Creek along Ky 876 (Barnes Mill Road) from ~100 m downstream of where a bridge crosses the stream, then upstream and upsection for a distance of ~300 m over several sets of falls until bedrock exposure becomes sporadic to absent. We sampled the stratigraphic section at approximately half-meter intervals, also taking samples at lithology changes. We collected a total 18 samples, all of which …

Lithology And Depositional Environments Of A Portion Of The Clays Ferry Formation (Middle And Upper Ordovician) Exposed At Silver Creek, Madison County, Kentucky, Autumn Murray

EKU Faculty and Staff Scholarship

We measure, describe, and interpret a carbonate stratigraphic section within the Clays Ferry Formation (Middle and Upper Ordovician) cropping out in Madison County, Kentucky (USGS Kirksville 7.5” quadrangle). The total thickness of the measured section is 4.76 m. We sampled the stratigraphic section at approximately half-meter intervals, also taking samples at lithology changes. We collected a total 20 samples, all of which were slabbed, and then selected 12 samples for thin section analysis.

Observed lithologies represent discrete depositional environments. The rocks are dominantly limestones with some carbonate shales deposited in shallow-water depositional environments that are generally open-marine, subtidal with perhaps …

Lithology And Depositional Environments Of A Portion Of The Clays Ferry Formation (Middle And Upper Ordovician) Exposed At Silver Creek, Madison County, Kentucky, Autumn Murray, Walter S. Borowski

EKU Faculty and Staff Scholarship

We measure, describe, and interpret a carbonate stratigraphic section within the Clays Ferry Formation (Middle and Upper Ordovician) cropping out in Madison County, Kentucky (USGS Kirksville 7.5” quadrangle). Outcrops are exposed within the bed of Silver Creek along Ky 876 (Barnes Mill Road) from ~100 m downstream of where a bridge crosses the stream, then upstream and upsection for a distance of ~300 m over several sets of falls until bedrock exposure becomes sporadic to absent. We sampled the stratigraphic section at approximately half-meter intervals, also taking samples at lithology changes. We collected a total 18 samples, all of which …

Changing Depositional Environments In An Upper Ordovician Stratigraphic Sequence, Ashlock Formation, Madison County, Kentucky, Kevin G. Greff, Walter S. Borowski

EKU Faculty and Staff Scholarship

We investigate the sedimentology, stratigraphy, and depositional environments of a 7-meter, Upper Ordovician limestone sequence cropping out in Richmond, Madison County, Kentucky. The stratigraphic section lies within the Ashlock Formation with good lateral exposure stretching along 200 meters of a highway roadcut. We took approximately 20 samples from the measured section, focusing on representative samples and lithologic transitions. We use standard laboratory procedures in slabbing rock samples and making thin sections.

The Ashlock Formation here consists of alternating layers of limey mudstone and limestone (field units A through F). Megafossils - brachiopods, bryozoans, trilobites, gastropods, ostracodes, coralline algae, and bivalves …

A Geologic Record Of Competing Sulfate-Depletion Processes Within Continental-Rise Sediments Overlying Methane Gas Hydrates Of The Blake Ridge Region (Continental Rise, Offshore Southeastern United States), Walter S. Borowski, Kathryn G. Takacs, Matthew K. Thompson

EKU Faculty and Staff Scholarship

Geochemical signals locked within sediments and sedimentary rocks record geochemical processes through geologic time. Sulfide minerals (elemental sulfur, iron monosulfides, and pyrite) are formed within marine sediments as dissolved sulfide is produced by various geochemical processes, which include sulfate reduction and anaerobic methane oxidation (AMO). The concentration and sulfur isotopic composition (d³⁴S) of sulfide minerals gives clues about the relative importance of these competing geochemical processes, and consequently about sedimentation rates and upward methane transport.

Marine sediments of the Blake Ridge(offshore South Carolina and Georgia) contain sulfide minerals that point to AMO as an important diagenetic process both …

A Geologic Record Of Methane Consumption Associated With Methane Gas Hydrates At Blake Ridge Region (Continental Rise, Offshore Southeastern United States), Walter S. Borowski, Kathryn G. Takacs, Matthew K. Thompson

EKU Faculty and Staff Scholarship

Geochemical signals locked within sedimentary rocks are a record of earth processes. Sulfide minerals (elemental sulfur, iron monosulfides, and pyrite) are formed within marine sediments by several different geochemical processes mediated by microbes. Investigating the concentration and sulfur isotopic composition (d³⁴S) of sulfide minerals gives clues about the relative importance of these competing geochemical processes.

Marine sediments of the Blake Ridge(offshore South Carolina and Georgia) contain sulfide minerals that point to anaerobic methane oxidation (AMO) as an important diagenetic process both today and in the recent geological past (Miocene). At the present-day methane-sulfate interface, upward-diffusing methane is consumed …

Sulfide Mineralization In Deep-Water Marine Sediments Related To Methane Transport, Methane Consumption, And Methane Gas Hydrates, Matthew K. Thompson, Walter S. Borowski, Charles K. Paull, William Ussler Iii

EKU Faculty and Staff Scholarship

Patterns of sulfide sulfur concentration and sulfur isotopic composition (d³⁴ S) are perhaps related to upward methane transport, especially in sediments underlain by methane gas hydrate deposits. Increased methane delivery augments the effect of anaerobic methane oxidation (AMO) occurring at the sulfate-methane interface (SMI). Sulfate and methane co-consumption results in production of dissolved sulfide at the interface that is eventually sequestered within sulfide minerals (elemental sulfur, iron monosulfide, pyrite).

We examine the sediments of two piston cores collected over the Blake Ridge gas hydrate deposits (offshore southeastern United States) by extracting total sedimentary sulfide using chromium reduction. We use …

Relative Concentration Of Solid-Phase Sulfide Species In Marine Sediments Overlying Gas Hydrate Deposits: Recognition Of The Role Of Anaerobic Methane Oxidation In Authigenic Sulfide Formation, Matthew K. Thompson, Walter S. Borowski, Charles K. Paull, William Ussler Iii

EKU Faculty and Staff Scholarship

Sulfide mineralization in marine sediments occurs when dissolved sulfide, produced by sulfate reduction processes, combines with dissolved iron to form iron sulfide minerals. Sulfide can be produced by oxidation of organic matter or by anaerobic methane oxidation (AMO), which involves the co-consumption of sulfate and methane. The latter process seems especially important within gas hydrate terrains like that of theBlakeRidge(offshore southeasternUnited States), where appreciable amounts of methane diffuse upward to the base of the sulfate reduction zone, or sulfate-methane interface (SMI).

We examine the sediments of two piston cores collected over the Blake Ridge gas hydrate deposits by sequentially extracting …

Sulfide Mineralization In Deep-Water Marine Sediments Related To Methane Transport, Methane Consumption, And Methane Gas Hydrates, Matthew K. Thompson, Walter S. Borowski, Charles K. Paull, William Ussler Iii

EKU Faculty and Staff Scholarship

Patterns of sulfide sulfur concentration and sulfur isotopic composition (d³⁴ S) are perhaps related to upward methane transport, especially in sediments underlain by methane gas hydrate deposits. Increased methane delivery augments the effect of anaerobic methane oxidation (AMO) occurring at the sulfate-methane interface (SMI). Sulfate and methane co-consumption results in production of dissolved sulfide at the interface that is eventually sequestered within sulfide minerals (elemental sulfur, iron monosulfide, pyrite).

We examine the sediments of two piston cores collected over the Blake Ridge gas hydrate deposits (offshore southeastern United States) by extracting total sedimentary sulfide using chromium reduction. We use …

Sulfide Mineralization In Deep-Water Marine Sediments Related To Methane Transport, Methane Consumption, And Methane Gas Hydrates, Matthew K. Thompson, Walter S. Borowski, Charles K. Paull, William Ussler Iii

EKU Faculty and Staff Scholarship

Patterns of sulfide sulfur concentration and sulfur isotopic composition (d³⁴S) are perhaps related to upward methane transport, especially in sediments underlain by methane gas hydrate deposits. Increased methane delivery augments the affect of anaerobic methane oxidation (AMO) occurring at the sulfate-methane interface (SMI). Sulfate and methane co-consumption results in production of dissolved sulfide at the interface that is eventually sequestered within sulfide minerals (elemental sulfur, iron monosulfide, pyrite).

We examine the sediments of two piston cores collected over the Blake Ridge gas hydrate deposits (offshore southeastern North America) by extracting total sedimentary sulfide using chromium reduction. We use …

Enrichments Of 34s In Sulfide Minerals Of Deep-Water Marine Sediments Of The Blake Ridge, Offshore Southeastern United States, Kathryn G. Takacs, Walter S. Borowski

EKU Faculty and Staff Scholarship

Past research shows that active sulfide mineralization occurs at the base of the sulfate reduction zone (SRZ) in modern, deep-water, continental-margin sediments that overlie methane gas hydrate. These sulfide minerals (elemental sulfur, Sº; iron monosulfides, ~FeS; and pyrite, FeS₂) are enriched in ³⁴S because of sulfate reduction and anaerobic methane oxidation (AMO) processes occurring above and near the sulfate-methane interface (SMI).

The data in this study show that 5 discrete zones of sulfide minerals are preserved in a 703.8-meter sediment column associated with methane gas hydrate. These zones of sulfide minerals are also enriched in ³⁴S. …