Event Title

Fluctuations at the Onset: A Study of the Mississippian Hydrosphere

Presenter Information

Calvin Wight, Colby CollegeFollow

Location

Parker-Reed, SSWAC

Start Date

30-4-2015 2:00 PM

End Date

30-4-2015 3:55 PM

Project Type

Poster

Description

The Mississippian period (~360-325 million years ago; Ma) of the Late Paleozoic represents the onset of the Late Paleozoic Ice Age (LPIA). This project explores the Mississippian hydrosphere using stratigraphic and geochemical data of near- and far-field evidence during a time of transitional climate. Globally-correlated cyclic stratigraphic transgressive-regressive sequences (sedimentation at varying sea levels) depict high-frequency, low-magnitude sea-level fluctuations, followed by larger magnitude low-frequency fluctuations that signify an icehouse-greenhouse transition. Global sea-level fluctuations (eustasy) directly correlate with the volume of accumulated glacial ice, and indicate changes in paleoclimate. Glacially driven eustasy is expressed as incised valley fills that depict rapid sea-level fall, which indicates widespread glaciation. Isotopic analyses of shallow-marine carbonate invertebrate shells act as proxies to constrain paleoceanographic chemistries. Implications of δ13C and δ18O isotope values depict a cool early Mississippian (Tournasian), followed by a warmer middle Mississippian (Visan), and a plunge in global temperature to glacial climates as the Mississippian came to a close. Cyclic stratigraphic successions, incised valley fill deposition, and isotope analyses of carbonates are correlated to indicate the driving forces of global climate change. These changes are observed in glacio-eustatic sea-level fluctuations and chemical composition of the Mississippian hydrosphere. These driving forces are a combination of: Milanković orbital cycles, eccentricity, obliquity, and precession; atmospheric pCO2 concentrations, and tectonics. Studying the effects of these forces offers insight on the magnitude of impact that modern climate change could have on humanity.

Faculty Sponsor

Herb Wilson

Sponsoring Department

Colby College. Geology Dept.

CLAS Field of Study

Natural Sciences

Event Website

http://www.colby.edu/clas

ID

1457

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Apr 30th, 2:00 PM Apr 30th, 3:55 PM

Fluctuations at the Onset: A Study of the Mississippian Hydrosphere

Parker-Reed, SSWAC

The Mississippian period (~360-325 million years ago; Ma) of the Late Paleozoic represents the onset of the Late Paleozoic Ice Age (LPIA). This project explores the Mississippian hydrosphere using stratigraphic and geochemical data of near- and far-field evidence during a time of transitional climate. Globally-correlated cyclic stratigraphic transgressive-regressive sequences (sedimentation at varying sea levels) depict high-frequency, low-magnitude sea-level fluctuations, followed by larger magnitude low-frequency fluctuations that signify an icehouse-greenhouse transition. Global sea-level fluctuations (eustasy) directly correlate with the volume of accumulated glacial ice, and indicate changes in paleoclimate. Glacially driven eustasy is expressed as incised valley fills that depict rapid sea-level fall, which indicates widespread glaciation. Isotopic analyses of shallow-marine carbonate invertebrate shells act as proxies to constrain paleoceanographic chemistries. Implications of δ13C and δ18O isotope values depict a cool early Mississippian (Tournasian), followed by a warmer middle Mississippian (Visan), and a plunge in global temperature to glacial climates as the Mississippian came to a close. Cyclic stratigraphic successions, incised valley fill deposition, and isotope analyses of carbonates are correlated to indicate the driving forces of global climate change. These changes are observed in glacio-eustatic sea-level fluctuations and chemical composition of the Mississippian hydrosphere. These driving forces are a combination of: Milanković orbital cycles, eccentricity, obliquity, and precession; atmospheric pCO2 concentrations, and tectonics. Studying the effects of these forces offers insight on the magnitude of impact that modern climate change could have on humanity.

http://digitalcommons.colby.edu/clas/2015/program/165