Bio

Geology of the Bosumtwi crater: The Bosumtwi crater was formed by a meteor impact about one million years ago and came to our attention while carrying out regional geological mapping along a portion of the Ashanti gold belt in Ghana. It is the largest recent crater with most of its original features still intact. Our geological efforts around the lake have been expanded and encompass a wide variety of geological features connected with the crater and its lake including its paleorecord of global climate change. Current efforts include the hydrology of the crater basin, geochemistry of the lake waters, clay and detrital mineralogy of the lake sediment in the bottom of the lake and in the terrace deposits, the dynamics of crater formation and the genesis of the impact glasses. Future efforts hope to include topography of the lake bottom, profiling of the bottom sediment and seismic refraction studies of the bedrock beneath the lake.

Sampling: Improved geological sample design can lead to improved interpretation of geochemical patterns and is crucial to the problem of computer simulation of ore grades in veins or in stratified deposits. Such models can be used for reserve estimation, production planning, monitor design, and confirmation sampling. During the past few years our efforts have concentrated on the methods needed for better simulations of ore grades. This has included the development of random number generators suitable for detailed simulation of grades in ore deposits and the extension of statistical time series analysis from the one dimensional case such that now practical simulations are possible in both two and three dimensions. Future efforts will be directed toward changing from unconstrained simulation towards constrained cases. The understanding developed from these simulations has already suggested important modifications to traditional sampling.

Ancient metallurgy: Mining activities in the near-east date right back to the beginning of the bronze age and are easily recognized by the form and nature of the slag heaps adjacent to these sites. We first encountered examples of such heaps while investigating a series of Pb-Zn deposits near Khuzdar in Balochistan. Since then we have looked at ancient slags at Lavrion associated with the silver deposits of classical Greece and ancient slags in Anatolia associated with lead, tin, and copper deposits of Turkey. Future work will most like concentrate on sites in Turkey, but we hope to do additional follow-up work on the slags associated with lead and copper deposits in Balochistan.

Specialization

• Exploration mineralogy
• Geological sampling
• Ancient metallurgy
• Geology of the Bosumtwi crater in Ghana

Publications

Turner, B.F., Gardner, L.R., and Sharp, W.E., 1995, "The Hydrology of Lake Bosuintwi, a climate sensitive lake in Ghana. West Africa." Journal of Hydrology (in press).

Watkins, A.P., Iliffe, J.E. and Sharp. W.E.. 1993, "The effects of extensional and transpressional tectonics upon the development of Birimian sedimentary facies in Ghana. W. Africa: evidence from the Bomfa/Beposa District, near Konongo." Journal of African Earth Sciences, v. 17 (4), p. 457-478.

Turner, B.F. and Sharp, W.E., 1994, "Unilateral ARMA processes on a square net by the herringbone method." Mathematical Geology, v. 26 (5). p. 557 - 564.

Sharp, W.E. and Bays. C., 1993, "A portable random number generator for single-precision floating-point arithmetic." Computers and Geoscience. v. 19 (4), p. 593 - 600.

Sharp, W.E. and Mittwede, S.K., 1994, "Was Kestel really the source of tin for ancient bronze?" Geoarchaeology, v. 9 (2), p. 155 - 158.

Siddiqui, S.A. and Sharp, W.E., 1993. "Lead smelting slags near Nal, Balochistan Province. Pakistan." Geoarchaeology, v. 8 (5). p. 395 - 411.