Hostname: page-component-cd9895bd7-dzt6s Total loading time: 0 Render date: 2024-12-26T21:20:58.903Z Has data issue: false hasContentIssue false
  • English
  • Français

Kaolinite, Opal-CT, and Clinoptilolite in Altered Tuffs Interbedded with Lignite in the Jackson Group, Texas

Published online by Cambridge University Press:  02 April 2024

A. L. Senkayi ,
D. W. Ming ,
J. B. Dixon  and
L. R. Hossner
A. L. Senkayi
Affiliation:
Department of Soil and Crop Sciences, Texas Agricultural Experiment Station, Texas A&M University, College Station, Texas 77843
D. W. Ming
Affiliation:
Department of Soil and Crop Sciences, Texas Agricultural Experiment Station, Texas A&M University, College Station, Texas 77843
J. B. Dixon
Affiliation:
Department of Soil and Crop Sciences, Texas Agricultural Experiment Station, Texas A&M University, College Station, Texas 77843
L. R. Hossner
Affiliation:
Department of Soil and Crop Sciences, Texas Agricultural Experiment Station, Texas A&M University, College Station, Texas 77843
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

The mineralogy of partially kaolinized strata interbedded with lignite at the San Miguel mine, Atascosa County, Texas, was investigated by X-ray powder diffraction and optical and scanning electron microscopy. The San Miguel lignite occurs in the lower Jackson Group (late Eocene) of southern Texas. Based on mineralogical and micromorphological data, some of these clay partings are probably volcanic in origin and were exposed to variable degrees of in situ kaolinization in a swamp environment. Coexistence of kaolinite, clinoptilolite, and opal-CT in several of these strata suggests that the partially kaolinized volcanic layers were subjected to a subsequent resilication process following burial. Kaolinite is the dominant mineral in the oldest and most kaolinized volcanic layer (underclay) below the lowest lignite bed (seam D). The kaolinite exhibits a well-developed vermicular morphology. The youngest volcanic layer, which occurs stratigraphically above the uppermost lignite seam, is characterized by pseudomorphs of volcanic glass shards and consists mainly of clinoptilolite. Movement of siliceous ground water from this layer to the underlying strata apparently provided silica-rich solutions from which opal-CT and large (as long as 300 μm) euhedral crystals of clinoptilolite precipitated in the fossilized plant roots, veinlets, and fractures within the underlying strata. Micromorphological relationships between the Sirich (opal-CT and clinoptilolite) and sulfide (marcasite and pyrite) minerals in the fossil roots and fractures suggest that the marcasite formed before and pyrite after the resilication process.

Keywords

ClinoptiloliteKaoliniteLigniteMarcasiteOpal-CTPlant rootsPyriteSilicationZeolite
Type
Research Article
Information
Clays and Clay Minerals , Volume 35 , Issue 4 , August 1987 , pp. 281 - 290
Copyright
Copyright © 1987, The Clay Minerals Society

References

Boles, J. R., 1972 Composition, optical properties, cell dimensions, and thermal stability of some heulandite group zeolites Amer. Miner. 57 1463 – 1493.Google Scholar
Brinkmann, K., 1977 Mineralogy and geochemistry of iron sulfides in the overburden of the Frechen open cast mine (Rhenish soft coal field) Neues Jahrb. Mineral. Abh. 129 333 – 352.Google Scholar
Edward, A. B. and Baker, G., 1951 Some occurrences of supergene iron sulfides in relation to their environment of deposition J. Sediment. Petrol. 21 34 – 46.Google Scholar
Grim, R. E. and Güven, N., 1978 Bentonites Amsterdam Elsevier.Google Scholar
Henderson, J. H., Jackson, M. L., Syers, J. K., Clayton, R. N. and Rex, R. W., 1971 Cristobalite authigenic origin in relation to montmorillonite and quartz origin in bentonites Clays & Clay Minerals 19 229 – 238.CrossRefGoogle Scholar
Kaiser, W. R. (1985) Texas lignite-status and outlook to 2000: Texas Bur. Econ. Geol. Circ. 76, 17 pp.Google Scholar
McNulty, J. E., 1978 Geology of the San Miguel lignite deposit: Proc. Gulf Coast Lignite Conf. on Geology, Utilization and Environmental Aspects Texas Bur. Econ. Geol. Rept. Inv. 90 79 – 83.Google Scholar
Ming, D. W. and Dixon, J. B., 1986 Clinoptilolite in south Texas soils Soil Sci. Soc. Amer. J. 50 1618 – 1622.CrossRefGoogle Scholar
Modreski, P. J., Verbeek, E. R. and Grout, M. A., 1983 Zeolites replacing plant fossils in the Denver Formation, Lakewood, Colorado Rocks Miner. 59 18 – 28.CrossRefGoogle Scholar
Mumpton, F. A., 1960 Clinoptiloite redefined Amer. Miner. 45 351 – 369.Google Scholar
Mumpton, F. A. and Ormsby, W. C., 1976 Morphology of zeolites in sedimentary rocks by scanning electron microscopy Clays & Clay Minerals 24 1 – 23.CrossRefGoogle Scholar
Pevear, D. R., Williams, V. E. and Mustoe, G. E., 1980 Kaolinite, smectite, and K-rectorite in bentonites: Relation to coal rank at Tulameen, British Columbia Clays & Clay Minerals 28 241 – 254.CrossRefGoogle Scholar
Reynolds, R. C. Jr. and Anderson, D.M., 1967 Cristobalite and clinoptilolite in bentonite beds of the Colville Group, northern Alaska J. Sediment. Petrology 37 966 – 969.CrossRefGoogle Scholar
Reynolds, W. R., 1970 Mineralogy and stratigraphy of Lower Tertiary clays and claystones of Alabama J. Sediment. Petrology 40 829 – 838.Google Scholar
Senkayi, A. L., Dixon, J. B., Hossner, L. R., Abder-Ruhman, M. and Fanning, D. S., 1984 Mineralogy and genetic relationships of tonstein, bentonite, and lignitic strata in the Eocene Yegua Formation of east-central Texas Clays & Clay Minerals 32 259 – 271.CrossRefGoogle Scholar
Snedden, J. W., 1979 Stratigraphy and environment of deposition of the San Miguel lignite deposit, northern McMullen and southeastern Atascosa Counties, Texas .Google Scholar