Stephan Oborny

University of Kansas | KU · Kansas Geological Survey

New δ³⁴Spy (pyrite) and δ³⁴SCAS (carbonate‐associated sulfate) across the Llandovery‐Wenlock boundary (∼432 Ma) provide evidence for the expansion of reduced marine environments during the Ireviken Biogeochemical Event. This event consists of a major positive carbon isotope excursion, increased biotic turnover, and other major perturbations and cha...

This paper provides a summary review of proposed nomenclatural revisions to the Zarah Subgroup of the Kansas City Group (Pennsylvanian) in Kansas and outlines changes adopted by the Kansas Geological Survey. The Iola Limestone, which comprises in ascending order the Paola Limestone, Muncie Creek Shale, and Raytown Limestone Members, is now consider...

The Upper Silurian Salina Group of eastern North America is well known for its thick evaporite successions and hydrocarbon resources. These strata have been assigned to numerous chronostratigraphic schemes within Ohio and Michigan and are currently identified by varying subsurface and outcrop nomenclatural schemes. These chronostratigraphic challen...

Diagenetic low-magnesium calcite (LMC) microcrystals constitute the framework that hosts most micropores in limestone reservoirs and therefore create the storage capacity for hydrocarbons, water, and anthropogenic CO2. Limestones dominated by LMC microcrystals are also commonly used for paleoclimate reconstructions and chemostratigraphic correlatio...

High-resolution paired analyses of δ¹³Ccarb and δ¹³Corg from a new drill core from Gotland, Sweden, demonstrate asynchronous positive change in the carbon isotope records during the onset of one of the major Silurian biogeochemical events known as the Mulde Event or “Big Crisis”. The detailed carbon isotope record presented here provides Δ¹³C (the...

Paired records of δ¹³Ccarb and δ¹³Corg across the Llandovery-Wenlock boundary demonstrate asynchronous behavior during the onset of the Ireviken Biogeochemical Event (IBE). The extremely high-resolution data produced from the Altajme Core, drilled from Gotland, Sweden, capture a negative excursion in δ¹³Corg during the initiation of the Ireviken Ex...

Silurian strata within the tristate area of Indiana, Ohio, and Kentucky have been thoroughly studied for well over a century. Due to rapid facies changes throughout the region numerous lithostratigraphic terminologies were established, many of which were difficult to correlate even over short distances. Recently these stratigraphic complexities hav...

The eastern and southeastern margins of the Appalachian Basin contain extensive exposures of Telychian through Pridoli (upper Silurian) strata. Litho- and biostratigraphic analyses of these strata over the last century provided a general means for their chronostratigraphic correlation to global series and stage boundaries. However, a rarity of zona...

A mass extinction event and perturbation to the global carbon cycle, known as the Mulde Event, took place during the late Wenlock Epoch of the Silurian Period. The Mulde positive carbon isotope excursion is recorded in the rock record by two positive excursions. Previous low-resolution studies indicated that the onset and end of the Mulde Excursion...

The build-and-fill model for mixed carbonate-clastic systems was originally developed to explain thin, widespread, icehouse depositional sequences that maintain more-or-less equal thickness over wide areas despite complex internal architecture that includes both topography-building and topography-filling depositional phases. Lithologic heterogeneit...

Cyclothem deposition in Miami and surrounding counties of the upper Linn and Zarah subgroups was dominated by carbonate mound development produced mainly during the falling stage of each cyclothem. These mounds were composed of photosynthetic phylloid algae which acted to produce and trap carbonate mud resulting in mound aggradation during the init...