Fosfato Sedimentar: geologia, sistemas naturais e...

Fosfato Sedimentar: geologia, sistemas naturais e implicações globais

Geól. Leandro G. Silva, MSc.

Pesquisador em Geociências

Sistemas Naturais

• Interação de sistemas

• Regulação da superfície

• Biota

• Paleoambientes

• Fatores econômicos

Bioelemental Sediments

• Nutrientes

• Depósitos sedimentares

• Interação biogênica

–Chert (C)

– Formação Ferrífera (I)

– Fosforito (P)

(Pufahl, 2010)

Phosphorite

• P-rich rock > 18 wt. % P2O5, can be 40 wt.% P2O5

• sedimentary phosphorite is a marine chemical sediment commonly associated with upwelling

• sedimentary phosphorite provides more than 80% of the total world production of phosphate rock

• Links natural systems

• annual consumption of phosphate rock ~200 million tons per year

• increasingly important source of U (50-200 ppm)

• peak phosphorus predicted in the next 30-50 years

Phosphorite

(Pufahl & Groat, 2017)

Sources & Reserves

(Jasinsky, 2016)

Sources & Reserves

(Cordell et al., 2009)

Demanda

(Cordell, 2011)

Phosphorus & Life

Phosphorus Cycle

Sedimentary Phosphorite

• Upwelling

• Trade winds

Sedimentary Phosphorite

Sedimentary Phosphorite

• Upwelling

• Margem Continental

Sedimentary Phosphorite

Sedimentary Phosphorite

• Mar Epicontinental

Phosphorus

Phosphorus

• Microbial degradation:– Sulfide oxidizing

– Sulfate reducing

– Breaks down organic matter

– Concentrate P in their cells

– Releases phosphate to pore water

– Promotes phosphogeneis

Phosphogenesis

Pufahl & Groat (2017)

Upwelling Non-Upwelling• Controls:– P concentration

– F Diffusion

– Bacteria

– Redox gradient

– Authigenesis

Pufahl & Hiatt (2012)

Phosphogenesis Redfield ratio (106C:16N:1P)

Phosphogenesis

• Redox gradient

• Organic matter

• Pyrite

• Dolomite

Pufahl & Hiatt (2012)

Pufahl & Groat (2017)

FrancolitaGeochemistry

• Authigenic Minerals

– Eh indicators

• Phosphate: links C, O and S

• Glauconite: Rb/Sr

• Pyrite: S isotopes

– Carbonates

Oceans and Atmosphere

• Great Oxygenation Event (2.4-1.8Ga)– Increase atm pO2

– Chemical weathering

– End of S-MIF

• Neoproterozoic Oxygenation Event (630-580Ma)– Oxygenation of

atmosphere and oceans

– Evolution of eukaryotes

– Evolution of metazoan

Pufahl & Hiatt (2012)Narbonne (2010)

Oceans and Atmosphere

• Glaciation & Oxygenation Events

Pufahl & Hiatt (2012)

Oceans and Atmosphere

• Deglaciation

• Weathering

• P input in the oceans

Biosphere – MicroorganismsSiphonophycus Myxococcoides

Arctacellularia

Melanocyrillium

Leiosphaeridia

Leiosphaeridia

Denezine (2018)Denezine (2018)

Biosphere – Ediacara Fauna

Ediacaran Fauna

(Xiao & Laflamme, 2008)

Precambrian vs Phanerozoic

Caird et al. (2017)

Pufahl & Hiatt (2012)

Precambrian vs Phanerozoic

Drummond et al. (2015)

Pufahl & Hiatt (2012)

Precambrian vs Phanerozoic

Pufahl & Hiatt (2012)

BHZ

BSB

Accummulation

Pufahl & Groat (2017)

• Classification

– Pristine

– Granular

Accummulation

Lima (2007)PristineGranular

Accummulation

Pufahl & Groat (2017)

Accummulation

Pufahl & Groat (2017)

Conclusões

• Fosforitos sedimentares são commodities essenciais para a economia brasileira

• Potencial para fosforito sedimentar é grande no Brasil

• Sistema complexo de acumulação e formação de depósitos econômicos

• Valor científico ligado a eventos climáticos globais, com consequencias em todas as esferas

• Evolução da vida

Obrigado!

Geól. Leandro G. Silva, MSc.

Leandro.Guimaraes@cprm.gov.br

Leandro.silva@queensu.ca