The Geology and Remarkable Thermal Activity of Norris Geyser Basin, Yellowstone National Park, Wyoming

Norris Geyser Basin is adjacent to the north rim of the Yellowstone caldera at the common intersection of the caldera rim and the Norris-Mammoth Corridor, a zone of faults, volcanic vents, and thermal activity that strikes north from the caldera rim to Mammoth Hot Springs. The dominant quartz sand is hydrothermally cemented by chalcedony and is extremely hard, thereby justifying the term hydrothermal quartzite. The fundamental water type in Norris Basin is nearly neutral in pH and high in Cl and SiO/sub 2/. Another common type of water in Norris Basin is high in SO/sub 4/ and moderately high in Cl, with Cl/SO/sub 4/ ratios differing considerably. This study provides no new conclusive data on an old problem, the source or sources of rare dissolved constitutents. An important part of this paper consists of examples of numerous changes in behavior and chemical composition of most springs and geysers, to extents not known elsewhere in the park and perhaps in the world. Hydrothermal mineralogy in core samples from three research holes drilled entirely in Lava Creek Tuff to a maximum depth of -331.6 m permits an interpretation of the hydrothermal alteration history. A model for large, long-lived, volcanic-hydrothermal activity is alsomore » suggested, involving all of the crust and upper mantle and using much recent geophysical data bearing on crust-mantle interrelations.« less