Sm-Nd and C-isotope chemostratigraphy of Ordovician epeiric sea carbonates, midcontinent of North America
type: CreativeWork
description: Interpreting and correlating epeiric sea sequences is key to understanding ancient marine environments. As a result, eNd, d13C and Sm/Nd profiles are developed as tools for interpreting epeiric sea carbonates. Previously, eNd and d13C profiles in epeiric sea carbonates have been used to study changes in the Nd isotope balance and C-cycle of adjacent ocean water. Instead, eNd, d13C and Sm/Nd profiles of Ordovician Midcontinent carbonates of North America demonstrate that fluctuations in sea level and depth are driving local changes in the eNd, d13C and Sm/Nd composition of epeiric seawater. Dissolved Nd derived from the Transcontinental Arch, Taconic Highlands and the Iapetus Ocean determine the eNd composition of Midcontinent seawater. As sea level fluctuated, submergence of the Arch and an influx of Iapetus ocean waters adjusted the Nd isotope balance of epeiric seawater. As a result, eNd profiles can be used to track the submergence history of the Late Ordovician Midcontinent. Comparison of stratigraphic variations in carbonate Sm/Nd ratios with sea level curves, conodont paleoecology, and the eNd profiles also suggests that variations in Sm/Nd ratios are related to changes in depth. However, processes effecting Sm/Nd ratios in epeiric seas may be varied and require further investigation. Sea level fluctuations and the waxing and waning of cool, nutrient rich, oxygen poor Iapetus waters onto the craton adjusted productivity and organic carbon burial rates on the Ordovician Midcontinent. Close to the Transcontinental Arch sea level rise caused an increase in organic carbon burial and productivity, while close to the Sebree Trough, and the influx of Iapetus waters, sea level rise caused a decrease in organic carbon burial and productivity. Differences in local C-cycling across a single epeiric sea encourage caution when using d13C profiles from epeiric sea carbonates to track changes in the C-cycle of adjacent oceans. Because of their connection to sea level fluctua…
abstract: Interpreting and correlating epeiric sea sequences is key to understanding ancient marine environments. As a result, eNd, d13C and Sm/Nd profiles are developed as tools for interpreting epeiric sea carbonates. Previously, eNd and d13C profiles in epeiric sea carbonates have been used to study changes in the Nd isotope balance and C-cycle of adjacent ocean water. Instead, eNd, d13C and Sm/Nd profiles of Ordovician Midcontinent carbonates of North America demonstrate that fluctuations in sea level and depth are driving local changes in the eNd, d13C and Sm/Nd composition of epeiric seawater. Dissolved Nd derived from the Transcontinental Arch, Taconic Highlands and the Iapetus Ocean determine the eNd composition of Midcontinent seawater. As sea level fluctuated, submergence of the Arch and an influx of Iapetus ocean waters adjusted the Nd isotope balance of epeiric seawater. As a result, eNd profiles can be used to track the submergence history of the Late Ordovician Midcontinent. Comparison of stratigraphic variations in carbonate Sm/Nd ratios with sea level curves, conodont paleoecology, and the eNd profiles also suggests that variations in Sm/Nd ratios are related to changes in depth. However, processes effecting Sm/Nd ratios in epeiric seas may be varied and require further investigation. Sea level fluctuations and the waxing and waning of cool, nutrient rich, oxygen poor Iapetus waters onto the craton adjusted productivity and organic carbon burial rates on the Ordovician Midcontinent. Close to the Transcontinental Arch sea level rise caused an increase in organic carbon burial and productivity, while close to the Sebree Trough, and the influx of Iapetus waters, sea level rise caused a decrease in organic carbon burial and productivity. Differences in local C-cycling across a single epeiric sea encourage caution when using d13C profiles from epeiric sea carbonates to track changes in the C-cycle of adjacent oceans. Because of their connection to sea level fluctua…
author: Fanton, Kerrie C.
language: en_US
keywords: C, Sm/Nd, Ordovician, Midcontinent, Nd, epeiric
date published: 2004-12-20
date modified: 2026-07-24T04:27:18Z
provider: University of Saskatchewan
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Saskatchewan

PropertyValue
property ID: Handle
value: https://hdl.handle.net/10388/etd-01042005-125256