TY - JOUR
T1 - The role of U-Pb ages of detrital zircons in sedimentology—An alarming case study for the impact of sampling for provenance interpretation
AU - Zimmermann, Udo
AU - Andersen, Tom
AU - Madland, Merete Vadla
AU - Larsen, Ingrid Skipenes
PY - 2015/5/1
Y1 - 2015/5/1
N2 - U-Pb ages on detrital zircons are often utilised for stratigraphic and paleogeographic interpretations and correlation. Sampling is carried out in such a way that the samples are representative for a formation, and then used for provenance identification and/or defining a maximum time limit for deposition. Is it possible that sedimentological factors and sampling would influence the results? This is perhaps an obvious consideration for sedimentologists, but is in many studies treated as a. secondary concern or even not mentioned.U-Pb LA-ICP-MS analysis on detrital zircons from two samples of Cambrian age (Herrería Formation, Cantabrian Mountains, Spain) revealed very different provenance signatures at the base and top of the formation. Both successions have been deposited in a shallow marine environment, are lithologically comparable (arenites, feldspathic arenites, siltstone, shales intercalated with marls and dolomite) and differ only slightly in age. Nearly 80% of all detrital zircons (n= 152; discordance. ≤ 10) at the base of the formation are younger than 650 Ma. Detrital zircons older than 1.0 Ga amount to only 10% (n= 16) of the entire population. In contrast, only around 32% of all detrital zircons from the top of the formation (n= 123; discordance ≤ 10) are younger than 650. Ma while more than 16% are Archean and nearly 50% Paleoproterozoic. This implies a fundamental change in provenance, with a shift from Neoproterozoic to Paleoproterozoic (1.9-2.2. Ga) aged sediment sources. Consequently, changes of sediment transport systems have had an extremely profound impact on the provenance of the formation. Therefore, when correlating sedimentary rocks, interpreting source rocks and modelling paleogeography from U-Pb ages of detrital zircons, sedimentological parameters are possibly paramount and these need to be at least discussed before any interpretation is made.
AB - U-Pb ages on detrital zircons are often utilised for stratigraphic and paleogeographic interpretations and correlation. Sampling is carried out in such a way that the samples are representative for a formation, and then used for provenance identification and/or defining a maximum time limit for deposition. Is it possible that sedimentological factors and sampling would influence the results? This is perhaps an obvious consideration for sedimentologists, but is in many studies treated as a. secondary concern or even not mentioned.U-Pb LA-ICP-MS analysis on detrital zircons from two samples of Cambrian age (Herrería Formation, Cantabrian Mountains, Spain) revealed very different provenance signatures at the base and top of the formation. Both successions have been deposited in a shallow marine environment, are lithologically comparable (arenites, feldspathic arenites, siltstone, shales intercalated with marls and dolomite) and differ only slightly in age. Nearly 80% of all detrital zircons (n= 152; discordance. ≤ 10) at the base of the formation are younger than 650 Ma. Detrital zircons older than 1.0 Ga amount to only 10% (n= 16) of the entire population. In contrast, only around 32% of all detrital zircons from the top of the formation (n= 123; discordance ≤ 10) are younger than 650. Ma while more than 16% are Archean and nearly 50% Paleoproterozoic. This implies a fundamental change in provenance, with a shift from Neoproterozoic to Paleoproterozoic (1.9-2.2. Ga) aged sediment sources. Consequently, changes of sediment transport systems have had an extremely profound impact on the provenance of the formation. Therefore, when correlating sedimentary rocks, interpreting source rocks and modelling paleogeography from U-Pb ages of detrital zircons, sedimentological parameters are possibly paramount and these need to be at least discussed before any interpretation is made.
KW - Detrital zircon
KW - Isotope geochemistry
KW - Provenance analysis
KW - Sedimentology
KW - Spain
UR - http://www.scopus.com/inward/record.url?scp=84924719759&partnerID=8YFLogxK
U2 - 10.1016/j.sedgeo.2015.02.006
DO - 10.1016/j.sedgeo.2015.02.006
M3 - Article
AN - SCOPUS:84924719759
SN - 0037-0738
VL - 320
SP - 38
EP - 50
JO - Sedimentary Geology
JF - Sedimentary Geology
ER -