Organic matter analyses of samples from a Fossil Alpine Tethyan Ocean Continental Transition (OCT) (Totalp, Platta, Tasna, Chenailllet)

Presence of various types of hydrocarbons in all the studied sample locations in the Western Alps (Chenaillet unit) and Central Alps (Totalp, Tasna and Platta units). The main hydrocarbon types found in the rocks of the fossil Tethyan OCT are n -alkanes, from C 16 to C 32 , low molecular weight polynuclear aromatic hydrocarbons (PAHs), hopanes, steranes, including 20R and 20S αββ isomers from C 27 to C 29, as well as 20 R and 20 S
diacholestanes and branched alkanes in the form of pristane and phytane.
The collected samples are primary divided to serpentinized mantle rocks, ophicarbonates and sedimentary rocks, described in more details in Geology P S C.xls file and in Mateeva et al 2017 (related article).

Samples and data collected between 2014 and 2017. All samples have their geographic latitude and longitude given in geology P S C. xls file and in Mateeva et al 2017 (related article).

TC and TOC - using a Carlo Erba Instrument NC2500 elemental analyser
OM extracted using Soxhlet extraction and quantified with GC-MS (Trace GC 1300, Thermoquest ISQ LT)
Stable isotopic analyses of organic carbon were prepared using a “sealed tube” method and injecting the resulting CO2 into a VG Sira 10 dual-inlet mass spectrometer. The isotope data was normalized to IAEA-CH7 calibration material and reported using the VPDB scale.
For the stable isotope analyses of carbonate veins 90 - 110 μg of calcite have been extracted with a small electrical hand drill, then converse to CO2 using a VG SIRA 10 MS Isocarb (common acid bath).

The purpose behind the collection of this data was to investigate the rapport between serpentinization and hydrogen-driven microorganisms in an ocean-continent transition (OCT) of magma-poor rifted.
Samples from the fossil Alpine Tethys OCT were examined for biomarkers and isotopic signals for any sign of methanotrophy within serpentinized exhumed mantle. The identified biomarkers and the isotopic data for bulk TOC are consistent with a marine origin but do not indicate a methanotrophic bio-system