Geochemical and isotopic characterization of trace fossil infillings: New insights on tracemaker activity after the K/Pg impact event

Claudia Sosa Montes De Oca, Francisco Javier Rodriguez-Tovar, Francisca Martínez-Ruiz

Research output: Contribution to journalArticle (Academic Journal)peer-review

Abstract

Geochemical and isotopic analyses of the CretaceousePaleogene (K/Pg) boundary deposits were conducted
at the Caravaca section (External Subbetic, southeast of Spain) in order to evaluate the recovery of
the macrobenthic tracemaker community and the bioturbational disturbance. Samples from the infilling
material of several lower Danian dark-colored trace fossils (Chondrites, Planolites, Thalassinoides and
Zoophycos) located in the uppermost 8-cm of the light upper Maastrichtian strata, as well as samples
from the host sedimentary rock of these trace fossils, were analyzed and compared with data from the
lower Danian deposits. The values of element ratios indicative of extraterrestrial contamination (Cr/Al,
Co/Al and Ni/Al) are higher in the infilling trace fossil material than in the upper Maastrichtian and lower
Danian deposits, which suggests a contribution of the ejecta layer. Regarding the isotope composition,
the d13C values are lower in the infilling material than in the Maastrichtian host sedimentary rocks
surrounding the traces, while the d18O are higher in the infilling material. The geochemical and isotopic
compositions of the infilling material evidence the unconsolidated character of the sediment, including
the red boundary layer. Softground conditions confirm a relatively rapid recovery by the macrobenthic
tracemaker community, starting a few millimeters above the K/Pg boundary layer. The mixture of the
infilling material of the trace fossils moreover reveals a significant macrobenthic tracemaker activity
affecting KePg boundary transition sediments that may have significantly altered original signatures.
Original languageEnglish
Pages (from-to)From 391 to 401
Number of pages10
JournalCretaceous Research
Volume57
DOIs
Publication statusPublished - 18 Apr 2015

Keywords

  • K/Pg boundary
  • Caravaca section
  • Geochemical anomalies
  • Trace fossils
  • Tracemarker recovery
  • Bioturbational disturbance

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