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

conference contribution
posted on 2023-05-24, 13:47 authored by Jacqueline HalpinJacqueline Halpin, Ross LargeRoss Large, Leonid Danyushevsky, Maslennikov, VV, Gregory, D, Lyons, TW, Elena LounejevaElena Lounejeva
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.

History

Publication title

Mineralogical Magazine: Goldschmidt 2013 Abstracts

Volume

77

Pagination

1245

ISSN

0026-461X

Department/School

School of Natural Sciences

Event title

Goldschmidt 2013

Event Venue

Florence, Italy

Date of Event (Start Date)

2013-08-25

Date of Event (End Date)

2013-08-30

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the earth sciences

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