Podiform chromite deposits occur in alpine peridotite and mafic complexes and fundamentally are tabular, pencil-shaped, or irregular in form. The chromite characteristically is anhedral and commonly shows effects of granulation and magmatic corrosion. Flow-layering, foliation, and lineation are parallel in most chromite deposits and peridotite host rocks, and normally pass through major rock units, including chromite; locally, foliation and lineation may cross layering. Most podiform deposits are oriented with their longer dimensions essentially parallel to layering or foliation in the host peridotite, but some are crosswise. In all podiform deposits, whether parallel or crosswise, internal flow structures are, to use Hans Cloos' terminology, harmonious with those in the country rock, except where disturbed by postmagmatic faulting. The relations between podiform and stratiform deposits are analogous to those between metamorphic and sedimentary rocks. Though relict structures formed by crystal settling are preserved in some massive ore, most features in podiform deposits are due to extensive flowage during re-emplacement, under magmatic conditions. As the rules governing sedimentary rocks apply in exploration of stratiform deposits, so metamorphic principles apply to podiform deposits. Evidence is presented to show that the chromite deposits in the Gule-man-Soridag district, Turkey, are podiform ; and that the Golalan ore body is closely related to nearby gabbroic rocks of normal alpine type. The Soridag deposits are regarded as originally podiform rather than as fault segments of stratiform deposits.
|Title||Principal features and origin of podiform chro-mite deposits, and some observations on the Guleman-Soridag District, Turkey|
|Authors||T. P. Thayer|
|Publication Subtype||Journal Article|
|Series Title||Economic Geology|
|Record Source||USGS Publications Warehouse|