Embed Size (px)
Citation preview
Miocene seep carbonates in Northern Italy:
Any evidence of paleo-gas hydrates?
“GAS HYDRATE IN SEDIMENTS” WORKSHOP TROMSØ, 26-28/03/2019
Claudio Argentino
Identification of paleo-SMT in the geologic record
CH4 + SO42- + + H20
Ca-Mg carbonates
(MDAC)
FeS, FeS2
Chemosynthetic fauna
Anaerobic oxidation of methane (AOM)
Jørgensen and Kasten (2006)
ArcheaSRB
Boetius et al. (2000)
Implications:
o Relationships with climate, tectonics
o Past GH destabilization
o Improve the accuracy of seismic interpretations
(e.g. buried MDAC PHAA?)
o Chemosynthetic communities
o …
Serov et al. 2017 PNAS
recent lucinids fossil lucinids
Argentino et al. 2019 Geosci
Seep deposits Sea-level
Exposed accretionary
wedge (Tertiary turbidite
successions)
Paleo-seeps developed on
wedge-top, slope,
intrabasinal highs
Miocene outcrops in northern Italy
Argentino et al. 2019 Geosci
Geological mapping Carbonate Facies
Trace metal proxies (REE, Mo-U)
Sr isotopes (87Sr/86Sr)
Mapping SSD
Research activities during the PhD
HOST SEDIMENTSMethane-derived CARBONATES
Stable C, O IsotopesXRPD +SEM
TOC, C/N
TS, S isotopes (d34S)
Claudio Argentino M3ES XXXI 8
Argentino et al. 2019 JMPG
Carbonate facies
Chemosynthetic faunaBrecciasConduits
Overpressure dissipation Shallow SMTVesicomyids Lucinids
Clathrite facies
Vuggy fabrics and collapse breccias
Greinert et al. (2001) and Bohrmann et al. (1998)
Clathrite facies - Apennine samples
Clathrite facies - Apennine samples
Argentino et al. 2019 Geosci
Argentino et al. 2019 Geosci
Inputs:Paleobathimetry = 1000 m Geothermal gradient = 30 °C/km Bottom water temperature =4 ° , 11 °CSalinity= Mediterranean salinity (3.8 %)
GHOZ ~ few tens of m
Argentino et al. 2019 Geosci
? ??
Chlatrite occurrence seems to coincide with third-order low stands…
Argentino et al. 2019 Geosci
“GAS HYDRATE IN SEDIMENTS” WORKSHOP TROMSØ, 26-28/03/2019
REMARKS:
• Fossil clathrites are rarely reported in the literature due to the elusive criteria for their recognition
• The northern Apennines (Italy) host several examples of chlatrites and paleo-methane seepage
• We can investigate how climate changes influenced cold seeps and gas hydrate systems in the past.
