Geological Survey of India, 27 Jawaharlal Nehru Road. Calcutta 700016, India.
Structural state of detrital alkali feldspars
Article first published online: 14 JUN 2006
Volume 24, Issue 1, pages 63–74, February 1977
How to Cite
SUTTNER, L. J. and BASU, A. (1977), Structural state of detrital alkali feldspars. Sedimentology, 24: 63–74. doi: 10.1111/j.1365-3091.1977.tb00120.x
- Issue published online: 14 JUN 2006
- Article first published online: 14 JUN 2006
- Manuscript received 16 February 1976; revision received 18 August 1976
The structural state of an alkali feldspar is determined by the nature of the distribution of Al and Si in the tetrahedral sites of the feldspar structure. This state is a function of a number of genetic controls including temperature, cooling rate, deformation, crystal size, and several chemical factors. Together these controls constitute a genetic regime. Identification of the structures of detrital feldspars may enable recognition of genetic regimes and be useful in provenance interpretation and mineral province definition.
A 2-peak method of X-ray diffraction (XRD) determination as a variant of an earlier proposed 3-peak method of structural state determination is used in this study. Total analytical time for each determination is about 50–55 min per grain. Results of structural state identification of 126 detrital feldspars from Holocene stream sands derived from volcanic, plutonic and metamorphic rocks are presented in order to illustrate the application and potential of the technique. Detrital feldspars from the metamorphic rocks are all maximum microcline; those from the plutons range from orthoclase to microcline depending on the age of the pluton, whereas those from the volcanic rocks are sanidines.