The Kari Kari caldera, Bolivia, and the Cerro Rico stock |
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Authors: | P.W. Francis M.C.W. Baker C. Halls |
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Abstract: | The rocks comprising the Kari Kari massif southeast of the city of Potosi, Bolivia, consist entirely of welded ignimbrites. It is argued that the massif constitutes the resurgent centre of a 20-m.y.-old resurgent caldera. Plutonic rocks are exposed in the south, but volcanic rocks of the caldera rim are exposed in the north, and indicate a shallower erosion level there. The volcanic rocks consist of a coarse moat deposit, consisting of angular fragments of basement material and juvenile clasts, overlain by an extensive garnet-bearing ignimbrite. A plant-fossil-bearing lacustrine deposit was laid down in a lake within the caldera. The Cerro Rico stock, noted for its silver-tin mineralisation, may be a late intrusion along the caldera ring fractures. |
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