J. Veizer et al., STRONTIUM ISOTOPE STRATIGRAPHY - POTENTIAL RESOLUTION AND EVENT CORRELATION, Palaeogeography, palaeoclimatology, palaeoecology, 132(1-4), 1997, pp. 65-77
A new generation Sr-87/Sr-86 isotope curve for the Phanerozoic seawate
r, based on a compilation of 3635 stratigraphically well defined and w
ell preserved skeletal components, results in a substantially narrower
band, with some discrepancies, if compared to the 'curve' of Burke et
al. (1982), which is based mostly on whole-rock samples. The results
obtained from low-Mg calcite shells (foraminifers, belemnites, brachio
pods and oysters) are mostly superior to those from phosphatic skeleta
l components, such as conodonts, even if the latter are exceptionally
well preserved (CAI less than or equal to 1.5). At this stage, the Pha
nerozoic data set based on fossils is patchy for the Cambrian, Upper O
rdovician-Lower Devonian and Upper Carboniferous-Triassic intervals. T
he major practical constraint that precludes delineation of an unequiv
ocal Sr isotope curve for the Phanerozoic seawater is the uncertainty
in the assignment of absolute ages to the samples. As a result the cur
ve is in reality a band. This is a reflection of the limitations of bi
ostratigraphy and geochronology that are inherited by any derivative c
orrelation and dating technique, including isotope stratigraphy. II is
therefore unlikely that, in the near future, the Sr isotope stratigra
phy will surpass the resolution capability of biostratigraphy as a glo
bal correlation tool. On the other hand, if complemented by lithostrat
igraphy, it is potentially a valuable tool for correlation of sequence
s on intrabasinal and regional scales. Taking into account the above l
imitations, careful consideration must be given to assignment of highe
r order isotope peaks to specific 'events' within a biozone and to the
use of such events as a global correlation tool. (C) 1997 Elsevier Sc
ience B.V.