Fluids circulation in crustal rocks and formation of biomolecules

1
Fluids circulation in crustal rocks and formation
of biomolecules

• Nils Holm
• Department of Geology and Geochemistry
• Stockholm University

2
Flow of water through oceanic crust
Degens, 1989
3
Ferromagnesian minerals

• Olivin e (Mg,Fe)2SiO4
• Pyroxenes Ca(Mg,Fe)Si2O6 augite
• (Mg,Fe)SiO3 hypersthene
• Amfibole Ca2(Mg,Fe)5Si8O22(OH)2 hornblende

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Serpentinisation of olivine

• 5Mg2SiO4 Fe2SiO4 9H2O
• forsterite fayalite
• 3Mg3Si2O5(OH)4 2Fe(OH) 2 Mg(OH)2
• serpentine brucite
• 3Fe(OH)2 Fe3O4 H2 2H20
• magnetite
• The reaction is characterised by high pH

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Formation of secondary minerals upon reaction of
komatiite at 75ºC
Ca-
Na-
X-axis Ultramafic rock reacted (grams) Schoonen
et al., 2004
6
Ocean Drilling ProgramLeg 201
2002
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Dissolved NO3- in pore water of ODP Leg 201
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Ethane (closed symbols) and propane (open
symbols) released from ODP Leg 201 sediments at
high pH
Hinrichs et al., 2005
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Gas hydrate polyhedra
10
Methane molecule adsorbed in the interlayer of
saponite
Sposito et al., 1999
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Fischer-Tropsch synthesis

• The industrial process
• CO H2 ? organic compounds
• In the presence of catalysts
• Fe or ZnO(Fe2O3, Cr2O3)
• ZnOCr2O3 ? linear alcohols
• ZnO Fe2O3 ? linear hydrocarbons

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Hydrothermal activity also occurs at convergent
margins
C. German
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Hydrogen and methane in some basalt and peridtite
environments

• area rock T?C pH H2(mmol/kg)
  CH4(mmol/kg)
• Lost City peridotite 40-75 9-9.8
  0.25-0.43 0.13-0.28
• 30?N gabbro (Kelley et
  al, 2001)
• Rainbow peridotite 364 2.9-3.1
  13.0 2.2
• 36?14N gabbro (Donval et
  al.,1997)
• Lucky Strike basalt 308-324 3.8-6.4
  0.04-0.72 0.3-0.7
• 37?17N (Charlou et al., 2000)

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The constituents of RNA(ribonucleic acid)
From Schwartz, 1998
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Mariana Trench in the western Pacific
Ocean (Mottl et al., 2003)
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No presence of an accretionary wedge
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Schematic cross-section of typical settings for
mud volcanoes in Mariana forearc
Fluids of the Conical Seamount have pH 12.6
and contain C1-C4 hydrocarbons and carboxylic
acids and are enriched in boron (x10) and
ammonia (Fryer et al., 1999)
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Composition of the pore water from an ODP drill
hole on South Chamorro Seamount
Mottl et al., 2003
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Composition of South Chamorro Seamount pore water
Mottl et al., 2003
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Aldehydes may be involved as reaction
intermediates
alkane H2O ? aldehyde 2H2 aldehyde H2O ?
carboxylic acid 2H2
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Ratios of the activities of carboxylic acids to
aldehydes
Schulte and Shock, 1993
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Pentose formation in the presence of borate
Ricardo et al., 2004
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Fischer-Tropsch synthesis II

• Purine bases (adenine, guanine) are easily
  formed over a wide temperature range when CO, H2
  and NH4 are allowed to react with native iron as
  a catalyst. The presence of HCN indicates its
  importance as an intermediate.
• Hayatsu et
  al., 1968

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HCN oligomers hydrolyze to amino acids and
nitrogen bases
All of the biologically important purines are
present in reasonable amounts in carbonaceous
meteorites, but only one pyrimidine (uracil) has
been detected, and that in much lower
concentration Stoks and Schwartz, 1979
From Ferris, 1984
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Conclusions

• Biogeochemical processes in the entire ocean
  floor may have been of importance to the
  formation of early life
• In theory, it is possible to synthesize most of
  the constituents of nucleotides in hydrothermal
  environments
• The origin of life is, perhaps, only possible on
  planets with plate tectonics