Iridium profiles and delivery across the Cretaceous/Paleogene boundary

Selen Esmeray-Senlet, Kenneth G. Miller, Robert M. Sherrell, Turgay Senlet, Johan Vellekoop, Henk Brinkhuis

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


We examined iridium (Ir) anomalies at the Cretaceous/Paleogene (K/Pg) boundary in siliciclastic shallow marine cores of the New Jersey Coastal Plain, USA, that were deposited at an intermediate distance (∼2500 km) from the Chicxulub, Mexico crater. Although closely spaced and generally biostratigraphically complete, the cores show heterogeneity in terms of preservation of the ejecta layers, maximum concentration of Ir measured (∼0.1–2.4 ppb), and total thickness of the Ir-enriched interval (11–119 cm). We analyzed the shape of the Ir profiles with a Lagrangian particle-tracking model of sediment mixing. Fits between the mixing model and measured Ir profiles, as well as visible burrows in the cores, show that the shape of the Ir profiles was determined primarily by sediment mixing via bioturbation. In contrast, Tighe Park 1 and Bass River cores show post-depositional remobilization of Ir by geochemical processes. There is a strong inverse relationship between the maximum concentration of Ir measured and the thickness of the sediments over which Ir is spread. We show that the depth-integrated Ir inventory is similar in the majority of the cores, indicating that the total Ir delivery at time of the K/Pg event was spatially homogeneous over this region. Though delivered through a near-instantaneous source, stratospheric dispersal, and settling, our study shows that non-uniform Ir profiles develop due to changes in the regional delivery and post-depositional modification by bioturbation and geochemical processes.

Original languageEnglish (US)
Pages (from-to)117-126
Number of pages10
JournalEarth and Planetary Science Letters
StatePublished - Jan 1 2017

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science


  • K/Pg boundary
  • advection–diffusion model
  • bioturbation
  • impact iridium
  • iridium inventory


Dive into the research topics of 'Iridium profiles and delivery across the Cretaceous/Paleogene boundary'. Together they form a unique fingerprint.

Cite this