BY

SWAPAN KR SAHOOGANQING JIANG, NOAH PLANAVSKY, BRIAN KENDALL, JEREMY OWENS, ARIEL ANBAR

AND TIMOTHY LYONS

125TH GSAANNUAL MEETINGDENVER, COLORADO30TH OCTOBER, 2013

TURBULENT TIMES FOR EARLY ANIMALS?

UNIVERSITY OF NEVADA, LAS VEGAS

Department of

GEOSCIENCE

Rise of Atmospheric O2Early Metazoans–632 Ma, Early O2 –2.3 Ga

Fossil and Metal Record

after Sahoo et al., 2012

after Lyons et al., 2009, Elements

after Sahoo et al., 2012, Nature

Early Proterozoic - GOE ~2.4 Ga

Late Proterozoic ~551 Ma

Early Metazoans~632 Ma

Trace Metals and Isotopes Rise of Early Animals and O2Evidence from Redox sensitive Metals

after Sahoo et al., 2012, Nature

Trace Metals and Oxygen Seawater Metals Record RedoxMetal/TOC Ratio’s Record Conc.

The sedimentary Metal/TOC* ratios track dissolved Metal concentration in seawater. *TOC Total Organic Carbon

Seawater Trace metals records information about marine redox landscape.

Mod

ern

Sedi

men

tsAn

cien

t

after Lyons et al., 2008, ESR

Redox Indicators How to calculate the chemical condition of the ocean

Iron (FeT)

Highly Reactive Fe (FeHR)

Non Reactive Fe (FeNR)

Fe Oxide (FeOxide)Fe Magnetite (FeMag)Fe Carbonate (FeCarb)Fe Pyrite (FePyrite)

Oxic vs. Anoxic

(FeHR/FeT)

Ferruginous vs. Euxinic (FePyrite/FeHR)

=

after Poulton and Canfield, 2011, Elements

Geology-Rock Record Study area, Location Maps and Age constrains for the Nanhua Basin

and Jiang et al., 2011, Gondwana Research

after Sahoo et al., 2012, Nature

The redox state of the ocean was euxinic, and record original signature of the ocean chemistry

SEM Analysis Pyrite Framboids - syngenetic depositional history

Backscattered electron (BSE) images of closely packed, typical pyrite framboids

after Sahoo et al., 2012, Nature

Multi-Proxy Geochemical Data Rise and Fall of Redox sensitive Metals

If no redox change across major boundaries, but metal enrichments: then1. Either there are change in fluxes —weathering

2. Change in oxidative state of the ocean

Geochemical Modeling Weathering Alone is not the DriverOxidation is the key

Even 1% Anoxic/euxinic sediments can counter balance even double the riverine flux. not the major driver

The oxidative state of the ocean was a primary driver for high Trace metalsafter Sahoo et al., 2012, Nature

Animals, Nutrients and O2Diversification Limited to certain

intervals. Rise and Fall of O2?

The Precambrian/Cambrian boundary – ocean chemistry was very much like Phanerozoic

— Low Fe, P but high Mo, V, U, Co, Cd (Chalcophilic bioessential metals)

We should question our self with Late Ediacaran biospheric evolution 1. Nutrient limitation feedbacks at various redox regimes

2. The protracted nature of Earth’s O2 rise

Acknowledgement Lot of People to ThankFriends and Colleagues

S.K. Sahoo G. Jiang N. Planavsky T. Lyons B. Kendall A. D. Anbar

X. Wang C. Scott

National Foundation of SciencesUniversity of California, RiversideLyons Lab: Jeremy Owens, Chris, Natasha, Megan and Steve Bates

Arizona State University, TempeGwyneth Gordon, Steve Romanielo

China University of Geosciences

University of Nevada, Las VegasCarbonate Mafia Group and Jeevan Jayakody

Thank You