Special Acknowledgement for the Work of Dr. David Blackwell: Influence and Contributions to Countless Geothermal Assessments and Products

摘要

The seminal work of David Blackwell has been a constant throughout the careers of many geothermal geoscientists for the past half century. His influence on this scientist began early in her career as his thoughts on temperature gradient and geothermal flow zones were studied since 1985, and used in developing a major publication in 1988 on hydrothermal outflow plumes. The influence of his continuing work was felt throughout the subsequent 29 years, up to and including the consultation of a 1977 paper (Blackwell and Chapman, 1977, from the first Geothermal Resources Council (GRC) meeting)) in the preparation of one of this year's (2014) GRC papers on temperature gradient variations as a function of varying thermal conductivities of rocks. Temperature gradients and heat flow are primary data and characteristics associated with geothermal systems, and continue to be among the most important types of data to collect in any system when evaluating potential. Measured temperature is the most definitive indicator of a geothermal system. His foundation work allowed for better understanding of systems from Valles caldera, to many Nevada systems, to Long Valley, to the Cascades, where his heat flow work and assessments, including gradient well drilling, were the foundation for knowledge of the Mt St. Helens system prior to its 1980 eruptions. Later, his "Forgotten Ones" paper (Richards and Blackwell, 2002) spurred the re-discovery and evaluation of many of the previously identified, but overlooked systems in Nevada, including re-introduction of the shallow temperature survey as an exploration tool. In all new geothermal system evaluations, small and large, one primary data set used to determine what is known of a system prior to developing an evaluation plan is the well-known SMU (Southern Methodist University) database, spearheaded by Dr. Blackwell. Multiple derivative products resulted from the basic gradient and heat flow data collection including of a series of maps through Nevada Bureau of Mines and Geology (Maps 141, 151, 161, to digital map services allowing queries and data selection and extraction), including more detailed site evaluations throughout the state. In 2008 and 2011, the work of Wisian, Blackwell and Richards (2001) was used to update known resource potential in Nevada, with this being the foundation, and still, best contribution to estimated heat losses at numerous geothermal systems. Additional work on calculated heat loss from systems throughout the Great Basin would greatly enhance our understanding of the extent of geothermal resources in this (and other) geothermally active regions now that much additional information is available. This methodology has been largely overlooked in many resource assessments and evaluations of geothermal favorabilities of regions and requires a re-visit.