Re os dating
ASPH and crude oil from the Streppenosa oil yield scattered data, perhaps related to effects of biodegradation.Streppenosa MALT yield a Model 1 age of 200.0 ± 5.2 Ma and initial = 4).
Collectively, our new data on alkane distribution, hopane and sterane biomarkers, major and trace element contents, and Re–Os concentrations and isotopic ratios of the oils and their fractions support the presence of two oil families.For example, the boundaries of many Phanerozoic systems, epochs, and stages are marked by the deposition of black shale units, several of which are coincident with mass extinction events.As such, the Re-Os geochronometer can be used to directly date some stratigraphic boundaries.This age and initial Os-isotopic composition are consistent with rapid oil generation shortly after Late Triassic source-rock formation, perhaps driven by magmatic-related heating.Here we document a potentially powerful geochronological tool that can be applied to single samples of crude oil.ASPH (insoluble in n-alkane) and maltene (MALT, soluble in n-alkane) fractions of oil were separated using n-pentane, n-hexane, n-heptane and n-decane solvents.
The ASPH contents of the Sciacca and Noto oils (26–33 wt%) are notably higher compared to the Streppenosa oil (7–12 wt% ASPH).
In addition to geochronology data, the Re-Os geochronometer provides the Os isotope composition (Os = 0.12) derived from cosmic dust and hydrothermal alteration of oceanic crust.
The Re-Os geochronometer can be used to date sedimentary successions lacking suitable horizons for traditional geochronology techniques such as Ar-Ar or U-Pb zircon geochronology.
In addition to geochronology data, the Re-Os system yields a wealth of information on the weathering fluxes into a particular basin or ocean at a given time in Earth history.
The Osi data can be used in a complementary way to Sr isotopes (but with a shorter residence time: ~10 kyr vs.
Recent studies with the Re-Os geochronometer are beginning to improve our understanding of the biological, geochemical, atmospheric, climatic and tectonic transformations recorded in the Proterozoic rock record.