Ordovician paleoceanography: Stable isotope and carbon-sulfur-iron evidence from the Caradocian Trenton Group, Mohawk Valley, New York

Oxygen isotope evidence from Caradocian Trenton Group brachiopods in the Mohawk Valley of New York suggests that Caradocian oceans were salinity-stratified and dominated at depth by warm, saline waters. δ\sp{18}O values of these brachiopods, which lived on the eastern continental slope of the North American craton over an apparent depth range of two to three kilometers, cannot be readily explained in terms of known burial diagenetic trends in the Mohawk Valley and presumably reflect depositional conditions. δ\sp{18}O values decrease with depth over the upper half of the Trenton paleoslope and range from $-$4.8 to $-$8.1 (PDB). These data, interpreted using a graphic modelling scheme constrained by both calcite isotopic compositions and seawater densities, suggest that both temperature and salinity increased with depth in the Caradocian oceans from intermediate to abyssal depths, and that warm saline deep waters (WSDW) dominated the latter. Modelling of isotopic data also suggests that the average oxygen isotopic composition of Caradocian seawater was no greater than about $-$4.0% (SMOW) and imply low-latitude earth-surface temperatures of less than 40$\sp\circ$C.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Geology

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Railsback, Loren Bruce

Contributors dc:contributor

• Anderson, Thomas F.

• Geology
• Physical Oceanography
• Geochemistry

Statement dc:rights

• Copyright 1989 Railsback, Loren Bruce

Language dc:language

eng

Identifier

AAI9010993
(UMI)AAI9010993

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/19094