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Secular trends in the global ocean revealed through trace elements in sedimentary pyrite


Halpin, JA and Large, RR and Danyushevsky, LV and Maslennikov, VV and Gregory, D and Lyons, TW and Lounejeva, E, Secular trends in the global ocean revealed through trace elements in sedimentary pyrite, Mineralogical Magazine: Goldschmidt 2013 Abstracts, 25-30 August 2013, Florence, Italy, pp. 1245. ISSN 0026-461X (2013) [Conference Extract]

DOI: doi:10.1180/minmag.2013.077.5.8


   Sedimentary pyrite incorporates trace elements (TE) during growth at levels far beyond the host bulk rock, making it a potentially powerful proxy for seawater chemistry in the marine rock record. We have developed a novel approach to simultaneously quantify a suite of TE via LA-ICPMS in sedimentary pyrite from marine black shales, as a proxy for chemical changes in palaeo-oceans. When our sedimentary pyrite data is compared with published whole-rock data, we see similar trends. We show that the temporal TE curves for 22 elements in sedimentary pyrite can be related to secular changes on Earth over 3.5 billion years.
   The Mo trend increases through time attributed to the significantly lower levels of oxygen in the atmosphere and oceans in the early Earth system [1]. The effects of the Great Oxidation Events are shown by the jumps in Mo at ~2500 Ma and 650 Ma, similar to what is seen in the bulk shale data. The broad Ni and Co trends are the opposite to Mo, attributed to cooling upper mantle temperatures and decreased eruption of komatiitic lavas from ~2700 Ma [2]. Pulses of elevated Ni and Co correspond to episodes of Large Igneous Province eruptions, particularly obvious with the Siberian Traps at the Permian-Triassic boundary. Phanerozoic trends in all TE are far more cyclical. We identify Se as being particularly redox sensitive, which allows us to explore finer-scale fluctuations through the Phanerozoic [3]. As our database expands in both scope and temporal detail, this new approach in measuring TE in sedimentary pyrite has exciting potential for chemical palaeo-ocean research.

Item Details

Item Type:Conference Extract
Keywords:pyrite, palaeo-oceanography, seawater proxy, GOE
Research Division:Earth Sciences
Research Group:Geology
Research Field:Structural geology and tectonics
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the earth sciences
UTAS Author:Halpin, JA (Dr Jacqueline Halpin)
UTAS Author:Large, RR (Professor Ross Large)
UTAS Author:Danyushevsky, LV (Professor Leonid Danyushevsky)
UTAS Author:Gregory, D (Dr Daniel Gregory)
UTAS Author:Lounejeva, E (Ms Elena Lounejeva Baturina)
ID Code:100948
Year Published:2013
Deposited By:Centre for Ore Deposit Research - CODES CoE
Deposited On:2015-06-03
Last Modified:2015-06-10

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