Strontium Chronology Service Available
Isobar Science is now offering a Strontium Chronology Service for dating marine carbonate samples. Strontium Isotope Ratios (87Sr/86Sr) within the ocean have varied through time, creating a predictable seawater curve that can be used for dating calibration.
Up to 600 million years can be dated using the Seawater Sr curve at a time resolution of ±1 million years. Dates are reported as 1σ and 2σ age ranges along with the median ages as years before present (B.P.).
Many marine samples can be dated using this method, including foraminifera, shells (bivalves, gastropods, brachiopods) and corals. To accurately date marine samples, it is assumed that the marine organism is grown fully in marine environments. Marginal marine environments are not optimal for this Strontium Geochronologies – like estuaries and river mouths as well as coastal environments – due to mixing with the riverine freshwater.
Isobar Science undertakes the 87Sr/86Sr measurements on the Neptune Plus multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS).
Strontium isotopic variation within the ocean is influenced by two main reservoirs: the relatively low 87Sr/86Sr mantle reservoir and the high 87Sr/86Sr continental reservoir (Brass, 1976). 
The former influences ocean water through the interaction between water and basalts within mid-oceanic ridges whilst the latter alters the oceanic strontium signature through river and groundwater flow resulting in continental weathering (Palmer and Edmond, 1989). Based on this premise, Kuznetsov et al. (2018) demonstrated the connection between oceanic 87Sr/86Sr variation and paleocean orogeny and supercontinent building events. The authors demonstrated increasing 87Sr/86Sr coincident with the formation of supercontinents – including Pangea, Gondwana and Rodinia. On the other hand, decreases in oceanic 87Sr/86Sr are correlated with oceanic ridge spreading and rifting – such as supercontinent disintegration.
In a recent study by Kocsis et al. (2022), the authors developed a Sr-isotope stratigraphy of maine deposits rich in fossils as a basis for studying past biodiversity in northern Borneo. After collecting the best preserved samples, the researchers were able to establish a set of numerical ages that fit with the known stratigraphic framework previously reported for the region. Additional samples allow for a more precise dating from important new sites in the region.
Finally, Bosio et al. (2022) utilized strontium dating to develop absolute ages for a series of fossil shark teeth used for paleoecological reconstructions. A variety of methods were used to assess the teeth with the best preservation state from a collection of Miocene sediments in southwestern Peru. The authors were able to demonstrate that following pre-screening, the teeth could be adequately dated using the strontium chronology technique, resulting in an important source material for chronostratigraphic and paleontological purposes.
Read more about the Strontium Chronology Service.
References
Bosio, G., Bianucci, G., Collareta, A., Landini, W., Urbina, M. and Di Celma, C., 2022. Ultrastructure, composition, and 87Sr/86Sr dating of shark teeth from lower Miocene sediments of southwestern Peru. Journal of South American Earth Sciences, 118, p.103909.
Kocsis, L., Briguglio, A., Cipriani, A., Frijia, G., Vennemann, T., Baumgartner, C. and Roslim, A., 2022. Strontium isotope stratigraphy of late Cenozoic fossiliferous marine deposits in North Borneo (Brunei, and Sarawak, Malaysia). Journal of Asian Earth Sciences, 231, p.105213.
Kuznetsov, A.B., Semikhatov, M.A. and Gorokhov, I.M., 2018. Strontium isotope stratigraphy: principles and state of the art. Stratigraphy and Geological Correlation, 26, pp.367-386.