eprintid: 46163
rev_number: 39
eprint_status: archive
userid: 608
dir: disk0/00/04/61/63
datestamp: 2010-10-15 18:58:28
lastmod: 2020-02-12 17:59:42
status_changed: 2012-08-07 13:35:34
type: article
metadata_visibility: show
item_issues_count: 0
creators_name: Shields, GA
title: A normalised seawater strontium isotope curve: possible implications for Neoproterozoic-Cambrian weathering rates and the further oxygenation of the Earth
ispublished: pub
divisions: UCL
divisions: A01
divisions: B04
divisions: C06
divisions: F57
note: © Author(s) 2007. This work is licensed under a Creative Commons License. For more information see http://creativecommons.org/licenses/by-nc-sa/2.0/deed.en
abstract: The strontium isotope composition of seawater is strongly influenced on geological time scales by changes in the rates of continental weathering relative to ocean crust alteration. However, the potential of the seawater 87Sr/86Sr curve to trace globally integrated chemical weathering rates has not been fully realised because ocean 87Sr/86Sr is also influenced by the isotopic evolution of Sr sources to the ocean. A preliminary attempt is made here to normalise the seawater 87Sr/86Sr curve to plausible trends in the 87Sr/86Sr ratios of the three major Sr sources: carbonate dissolution, silicate weathering and submarine hydrothermal exchange. The normalised curve highlights the Neoproterozoic-Phanerozoic transition as a period of exceptionally high continental influence, indicating that this interval was characterised by a transient increase in global weathering rates and/or by the weathering of unusually radiogenic crustal rocks. Close correlation between the normalised 87Sr/86Sr curve, a published seawater δ34S curve and atmospheric pCO2 models is used here to argue that elevated chemical weathering rates were a major contributing factor to the steep rise in seawater 87Sr/86Sr from 650 Ma to 500 Ma. Elevated weathering rates during the Neoproterozoic-Cambrian interval led to increased nutrient availability, organic burial and to the further oxygenation of Earth's surface environment. Use of normalised seawater 87Sr/86Sr curves will, it is hoped, help to improve future geochemical models of Earth System dynamics.
date: 2007-07
official_url: http://www.electronic-earth.net/2/35/2007/ee-2-35-2007.html
vfaculties: VMPS
oa_status: green
language: eng
primo: open
primo_central: open_green
article_type_text: Article
verified: verified_manual
elements_source: Manually entered
elements_id: 98785
lyricists_name: Shields, Graham
lyricists_id: GASHI56
full_text_status: public
publication: eEarth
volume: 2
pagerange: 35 - 42
issn: 1815-381X
citation:        Shields, GA;      (2007)    A normalised seawater strontium isotope curve: possible implications for Neoproterozoic-Cambrian weathering rates and the further oxygenation of the Earth.                   eEarth , 2    35 - 42.          Green open access   
 
document_url: https://discovery.ucl.ac.uk/id/eprint/46163/1/46163_Shields_2007_eEarth.pdf