SELECTED GREAT BASIN PLAYA CLAYS.
Abstract
Mineralogical studies of samples from Deep Springs Playa, Calif., Mud Lake and Humboldt Playa, Nevada, Sevier Playa, Utah and the Animas Playa, New Mex., indicate that the mica-type clay minerals illite, vermiculite, and montmorillonite are prominent in these playa crusts. These widely separated localities suggest a general distribution. The weathering of the mica-type layer silicates results in the development of intensive heterogeneity of lattice layers along the c-direction. The continuous scattering in the lower angle region 20 = 4-8.8 degrees shows gradual transitions between mica-type layers with different basal spacings. Further, there is an intensive disorder in a-b planes of many layers, i.e., random displacements of the layers causing 'continuous scattering' accompanying the normal Bragg reflections. The b-dimensions and the high MgO+FeO+Fe2O3 contents of the mica-type layers indicate their derivation from tetrasilicic members of the dioctahedral mica-type layers. The existence of sensitive layers like those of vermiculite and montmorillonite in the playas is important in explaining the physical behaviour of the surface of the playas. These layers exfoliate when dried and also expand with an increase in humidity. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 1965
- Accession Number
- AD0617554
Entities
People
- Necip Guven
- Paul F. Kerr
Organizations
- Columbia University