Berthierine from the Lower Cretaceous Clearwater Formation, Alberta, Canada

ERC Hornibrook, FJ Longstaffe

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

76 Citations (Scopus)

Abstract

Berthierine occurs as pore-linings of well crystallized laths of variable thickness in oil-sands of the Clearwater Formation, Alberta, Canada. Berthierine crystallized early in diagenesis within portions of a deltaic/estuarine complex dominated by brackish to fresh water. Separates prepared using high gradient magnetic separation contain approximately equal amounts of monoclinic and orthohexagonal berthierine. Minor, but variable, quantities of inseparable, iron-rich impurities mainly consist of chamosite Ib and IIb, and Fe-rich smectitic clays. Clearwater Formation berthierine has a range of chemical compositions that differ from those reported for most other berthierines. The SiO2 (27-35 wt%), Fe2O3 (5-8 wt%) and Al2O3 (16-18 wt%) contents for Clearwater Formation berthierine fall between values normally reported for berthierine and odinite. The average structural formula of five samples studied in detail is (Fe1.012+Al0.82Mg0.46Fe0.283+ Mn(
Translated title of the contributionBerthierine from the Lower Cretaceous Clearwater Formation, Alberta, Canada
Original languageEnglish
Pages (from-to)1 - 21
Number of pages22
JournalClays & Clay Minerals
Volume44(1)
Publication statusPublished - 1996

Bibliographical note

Publisher: CLAY MINERALS SOCIETY, PO BOX 4416, BOULDER, CO 80306

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