K-Ca ages of authigenic sediments: Examples from Paleozoic glauconite and applications to low-temperature thermochronometry

M. Robinson Cecil, Mihai N. Ducea

Research output: Contribution to journalArticle

8 Scopus citations

Abstract

K-Ca ages of Cambrian glauconites from the Llano uplift, central Texas, were determined in order to re-evaluate the ability of the K-Ca system to constrain the timing of deposition of sedimentary packages. All of the K-Ca ages presented here were found to be younger than their stratigraphic ages. In addition to being too young, the K-Ca ages are also highly variable, ranging in age from Silurian to Permian. The oldest subset of glauconite ages are in agreement with previously published Rb-Sr ages from the same outcrop and provide further evidence for there having been a post-depositional thermal or recrystallization event that reset both the Rb-Sr and K-Ca systems. The range of younger glauconite K-Ca ages is similar to the distribution of available apatite fission track ages for the Llano basement. K-Ca ages are interpreted as thermochronologic data reflecting partial retention of Ca in thermally fluctuating basin conditions. Estimates of the closure temperature of Ca in glauconite are found to be 60-90°C for cooling rates of ~0.5-1°C/My. The K-Ca system is potentially useful as a low-temperature thermochronometer with closure temperatures <100°C for glauconite.

Original languageEnglish (US)
Pages (from-to)1783-1790
Number of pages8
JournalInternational Journal of Earth Sciences
Volume100
Issue number8
DOIs
StatePublished - Nov 1 2011

Keywords

  • K-Ca isotopes
  • Sedimentary rocks
  • Thermochronology

ASJC Scopus subject areas

  • Earth and Planetary Sciences(all)

Fingerprint Dive into the research topics of 'K-Ca ages of authigenic sediments: Examples from Paleozoic glauconite and applications to low-temperature thermochronometry'. Together they form a unique fingerprint.

  • Cite this