Evolution of Atlantic deep-water circulation: from the greenhouse to the icehouse
To better understand how the evolution of Cenozoic deep-water circulation related to changes in global climate and ocean basin configuration, we generated Nd isotope records from Ocean Drilling Program sites in the southeastern Atlantic to track deep water mass composition through time. We used foss...
Main Author: | |
---|---|
Other Authors: | , , , |
Format: | Book |
Language: | English |
Published: |
Texas A&M University
2005
|
Subjects: | |
Online Access: | https://hdl.handle.net/1969.1/2609 |
id |
fttexasamuniv:oai:oaktrust.library.tamu.edu:1969.1/2609 |
---|---|
record_format |
openpolar |
spelling |
fttexasamuniv:oai:oaktrust.library.tamu.edu:1969.1/2609 2023-07-16T03:52:14+02:00 Evolution of Atlantic deep-water circulation: from the greenhouse to the icehouse Via, Rachael Kathleen Thomas, Deborah J. Malone, Mitchell J. Orsi, Alejandro H. Slowey, Niall 2005-11-01 1918592 bytes electronic application/pdf born digital https://hdl.handle.net/1969.1/2609 en_US eng Texas A&M University https://hdl.handle.net/1969.1/2609 paleoceanography Nd isotope geochemistry Book Thesis Electronic Thesis text 2005 fttexasamuniv 2023-06-27T22:55:32Z To better understand how the evolution of Cenozoic deep-water circulation related to changes in global climate and ocean basin configuration, we generated Nd isotope records from Ocean Drilling Program sites in the southeastern Atlantic to track deep water mass composition through time. We used fossil fish debris from ODP Sites 1262-1264 (Leg 208), spanning present-day water depths of 2500-4750 m, to reconstruct the isotopic signature of deep waters over the past ~53 Ma. The data indicate an initial transition from relatively non-radiogenic values (??Nd=~-10) at 53 Ma to more radiogenic values (~-8.5) at ~32 Ma. From ~32 Ma to 3.85 Ma, the Nd signal becomes more nonradiogenic, ~-12.3 at the top of the record. Comparison of our data with Nd isotopic records derived from a North Atlantic Fe-Mn crust show similar non-radiogenic values (~-10.5) in the 53??32 Ma interval and a trend toward more non-radiogenic values beginning at ~20 Ma. The data likely reflect an overall shift from a Southern Ocean deep water source to the ultimate incursion of deep waters from the North Atlantic. The non-radiogenic values at the base of the record reflect a Southern Ocean source of deep water. The shift toward more radiogenic values indicates an increased contribution of Pacific waters to the Southern Ocean source as the tectonic gateways changed after ~35-33 Ma. The subsequent trend toward more non-radiogenic Nd isotope values is approximately concurrent with the increase of benthic foraminiferal ??18O values, based on comparison with a compilation of global data. Thus, changes in oceanic gateway configuration in addition to overall cooling and the build-up of continental ice on Antarctica may have altered the Nd isotope character of Southern Ocean deep waters during the early Oligocene. Book Antarc* Antarctica North Atlantic Southern Ocean Texas A&M University Digital Repository Pacific Southern Ocean |
institution |
Open Polar |
collection |
Texas A&M University Digital Repository |
op_collection_id |
fttexasamuniv |
language |
English |
topic |
paleoceanography Nd isotope geochemistry |
spellingShingle |
paleoceanography Nd isotope geochemistry Via, Rachael Kathleen Evolution of Atlantic deep-water circulation: from the greenhouse to the icehouse |
topic_facet |
paleoceanography Nd isotope geochemistry |
description |
To better understand how the evolution of Cenozoic deep-water circulation related to changes in global climate and ocean basin configuration, we generated Nd isotope records from Ocean Drilling Program sites in the southeastern Atlantic to track deep water mass composition through time. We used fossil fish debris from ODP Sites 1262-1264 (Leg 208), spanning present-day water depths of 2500-4750 m, to reconstruct the isotopic signature of deep waters over the past ~53 Ma. The data indicate an initial transition from relatively non-radiogenic values (??Nd=~-10) at 53 Ma to more radiogenic values (~-8.5) at ~32 Ma. From ~32 Ma to 3.85 Ma, the Nd signal becomes more nonradiogenic, ~-12.3 at the top of the record. Comparison of our data with Nd isotopic records derived from a North Atlantic Fe-Mn crust show similar non-radiogenic values (~-10.5) in the 53??32 Ma interval and a trend toward more non-radiogenic values beginning at ~20 Ma. The data likely reflect an overall shift from a Southern Ocean deep water source to the ultimate incursion of deep waters from the North Atlantic. The non-radiogenic values at the base of the record reflect a Southern Ocean source of deep water. The shift toward more radiogenic values indicates an increased contribution of Pacific waters to the Southern Ocean source as the tectonic gateways changed after ~35-33 Ma. The subsequent trend toward more non-radiogenic Nd isotope values is approximately concurrent with the increase of benthic foraminiferal ??18O values, based on comparison with a compilation of global data. Thus, changes in oceanic gateway configuration in addition to overall cooling and the build-up of continental ice on Antarctica may have altered the Nd isotope character of Southern Ocean deep waters during the early Oligocene. |
author2 |
Thomas, Deborah J. Malone, Mitchell J. Orsi, Alejandro H. Slowey, Niall |
format |
Book |
author |
Via, Rachael Kathleen |
author_facet |
Via, Rachael Kathleen |
author_sort |
Via, Rachael Kathleen |
title |
Evolution of Atlantic deep-water circulation: from the greenhouse to the icehouse |
title_short |
Evolution of Atlantic deep-water circulation: from the greenhouse to the icehouse |
title_full |
Evolution of Atlantic deep-water circulation: from the greenhouse to the icehouse |
title_fullStr |
Evolution of Atlantic deep-water circulation: from the greenhouse to the icehouse |
title_full_unstemmed |
Evolution of Atlantic deep-water circulation: from the greenhouse to the icehouse |
title_sort |
evolution of atlantic deep-water circulation: from the greenhouse to the icehouse |
publisher |
Texas A&M University |
publishDate |
2005 |
url |
https://hdl.handle.net/1969.1/2609 |
geographic |
Pacific Southern Ocean |
geographic_facet |
Pacific Southern Ocean |
genre |
Antarc* Antarctica North Atlantic Southern Ocean |
genre_facet |
Antarc* Antarctica North Atlantic Southern Ocean |
op_relation |
https://hdl.handle.net/1969.1/2609 |
_version_ |
1771544939203657728 |