William D. Johns
Professor Emeritus
education: University of Illinois, 1952
interest: Clay Mineralogy, Sediment Diagenesis and Organic Geochemistry

email: JohnsW@missouri.edu
office: 101 Geological Sciences Bldg.
phone: 573-882-3785
fax: 573-882-5458

Research

For some time, the research interests of Bill Johns have included mineralogical and chemical studies of the diagenesis of pelitic sediments in relatively young sedimentary basins.

Although initially concentrating on the Tertiary section of the Gulf Coast province, recent studies extend to the Vienna Basin of Austria, in collaboration with colleagues at the University of Vienna and the Austrian National Petroleum Company. Most recently, these studies have moved eastward into the various Pannonian basins of Hungary, Slovakia, and the Czech Republic. These studies have concentrated on the correlation of clay mineral transformations with depth with the changes in coexisting organic matter (kerogen), using both mineralogical and organic maturation criteria as temperature indicators. Research results have led to the hypothesis that the clay mineral matrix of potential petroleum sources rocks acts as a catalytic medium for organic petroleum-forming reactions at relatively low temperatures.

These considerations also have led to an attempt to define and characterize the nature of catalytic activity on clay mineral and layer silicate surfaces in laboratory studies. Based on the bulk properties of pure clays, it is hypothesized that the source of catalytic activity is Bronsted acidity developed on mineral surfaces by the hydrolysis of water solvated to multivalent surface-adsorbed metal ions.

In an attempt to prove, revise or reject these model hypotheses, x-ray photoelectron spectroscopy (XPS) currently is used to directly examine and analyze the surfaces of layer silicates, including clays. With XPS analysis, only the outer few layers of a crystal are analyzed so that minor adsorbed constituents (in terms of bulk composition) can be quantitatively analyzed when concentrated at the crystal surface.

The means now exist to study the adsorption of minor amounts of metals and even organic species under various conditions of adsorption, and to determine directly partitioning properties of clay surfaces, for example, when they are exposed to metals or organic molecules in aqueous solution. This type of study has great potential in providing fundamental information of importance to environmental sedimentology.
 

Selected Publications

Johns, W.D. and Hoefs, J., 1985, Maturation of organic matter in Tertiary sediments of the Vienna Basin: Tscherm. Min. Pet. Mitt., v. 34, p. 143-58.

Johns, W.D. and McKallip, T.M., 1988, Specific catalytic activity of illite/smectite clays from the Vienna Basin, Austria: Bull. AAPG, v. 73, p. 472-82.

Johns, W.D. and Ulkus, R., 1993, Clay mineral activators and hydrocarbon generation during experimental pyrolysis: Geologica Carpathica-Clays, v. 1, no. 2 , 8 p.

Francu, J., V. Sucha, R., and Johns, W.D., 1995, Illite/smectite expandability as related to diagenesis and geothermal conditions in the West Carpathian-Pannonian region, central Europe, Geology (G.S.A. Pub.)

Johns, W.D., X-ray photoelectron spectroscopic study of layer charge magnitude in micas and illite/smectite clays, Clay Minerals.

Last Modified: winter 2008