GREEN FERRIC CLAY IN NONMARINE SANDSTONES OF THE REWAN GROUP, SOUTHERN BOWEN BASIN, EASTERN AUSTRALIA

Accessory green ferric clay occurs in fluvial litharenites of the Earl y Triassic Rewan Group. Although resembling glauconitic minerals in th in-section, electron microprobe analyses indicate that the green ferri c clay is mainly ferric illite. The ferric illite may have formed in a small hypersaline lake or well drained, flood-plain soil, and its pre sence in the Rewan Group cannot be used to support a notion that the u nit is partly marine influenced. Identification of the ferric illite b y electron microprobe analysis shows that some green ferric clays, par ticularly those that resemble glauconitic minerals optically, may requ ire precise quantitative elemental analysis before they can be used as a basis for environmental interpretation. Green ferric clay in the Re wan Group also includes detrital celadonite that most likely originate d in a volcanic are setting.