PREVIOUS SPEAKERS IN THE S. THOMAS CROUGH MEMORIAL LECTURE SERIES:

W.J. Morgan (Princeton Univ.) G.A. Thompson (Stanford Univ.) J.G. Sclater (Univ. Calif., San Diego) D.L. Turcotte (Univ. Calif. Davis) th L.L. Sloss (Northwestern Univ.) D. Jurdy (Northwestern University) 26 D.L. Anderson (Caltech) H. Pollack (University of Michigan) M.L. Zoback (US Geological Survey) Marcia McNutt (U.S. Geol. Survey) J. Oliver (Cornell University) Amos Nur (Stanford University) S. THOMAS CROUGH E. Shoemaker (US Geological Survey) Robert B. Smith (Univ. of Utah) D. McKenzie (Cambridge Univ.) Ross S. Stein (US Geol. Survey) MEMORIAL LECTURE R. Van der Voo (Univ. of Michigan) Roger Bilham (Univ. of Colorado) T.H. Jordan (Univ. Southern Calif.) Jim Rice (Harvard University) F.M. Richter (Univ. of Chicago) H.J. Melosh (Purdue Univ. ) S.C. Solomon (Carnegie Inst. Seth Stein (Northwestern Univ.) of Washington) Craig Jones (University of Colorado) The Ouachita Orogenic Belt:

New Results, A Synthesis, and

Global Analogs

The S. Thomas Crough Memorial Lecture series in Tectonophysics is made possible by gifts from Tom’s family, G. Randy Keller relatives, former advisors, instructors, friends, colleagues, students, and the Purdue Research Foundation. University of Oklahoma

Thursday, February 13, 2014 3:30p.m., Room 1252 HAMP

Sponsored by the S.T. Crough Memorial Fund and the Department of Earth and Atmospheric Sciences, Purdue University Refreshments at 3:00 pm, Room 2201

Abstract The Ouachita orogenic belt is a somewhat underappreciated but major tectonic feature that winds its way across the southeastern U. S., S. THOMAS CROUGH was born in Boston, Arkansas, Oklahoma, and Texas before disappearing into Mexico. My Massachusetts in 1946. He joined the Department of students, colleagues, and I have been working to better understand the Earth and Atmospheric Sciences at Purdue University in structure and evolution of the Ouachita orogen for many years. As part July 1980 and made West Lafayette his home. He passed of these efforts, we have complied a wide variety of geological and away on December 3, 1982. He is survived by his wife, geophysical data and continue to undertake integrated geological and Faith and his two sons, Ethan and David. In addition to geophysical studies with them. Understanding the structure and this lecture series, special issues of two journals - evolution of the Ouachita orogen is a challenge because it is mostly Tectonophysics and Journal of Geophysical Research - have been dedicated to his memory. buried, deep drilling results are scarce, and deep geophysical results are sparse. Some new 3-D seismic reflection data have been released for Tom received his B.S. in Political Science from Princeton analysis, and the results show interesting new details about the relation- University. During his enrollment in the Harvard Law ships between Paleozoic and Precambrian structures. Specifically, the School, his genuine interest in and love for geosciences complexity of the triple junction between the Southern Oklahoma brought him to the University of Michigan, where he aulacogen and the Cambrian margin of North America, as well as, its obtained his M.S. degree in geophysics. He completed effects on the Ouachita orogenic belt has been refined. Other new his Ph.D. in geophysics at Stanford University. Prior to results show that the Llano uplift itself is a distinct crustal block that joining Purdue as an Assistant Professor, he was a post- affected the track of the Cambrian rifting that formed the sinuous doctoral scholar at Woods Hole Oceanographic Institu- continental margin along which the Ouachita orogenic belt formed. We tion, and a visiting scientist and research associate at have also learned much by studying similar features in Europe and Princeton University.

Asia. Most aspects of the tectonic history of the Ouachita orogen and In his brief but highly productive career, Tom achieved an the Variscan orogen (an element of the Trans-European suture zone) are admirable status in the field of Tectonophysics and similar. In a tectonic sense, they are geographically linked, because at Tectonics. His curiosity and intuition, together with his the end of the Paleozoic, one could have traveled from Texas to central ability to be analytical and critical, made him a distin- Europe following a continuous orogenic belt. guished scientist. His contribution to the geosciences on the thermal behavior of the lithosphere, hot spots, formation of kimberlites, elevation of ocean floors and Biography oceanic islands, rifting, uplifts and erosion of continents have appeared in the form of several papers, in respected G. Randy Keller is a Professor in the School of Geology and Geophysics at scientific journals. the University of Oklahoma and holder of the Edward Lamb McCollough Chair in Geophysics. He also serves as the Director of the Oklahoma Geological Survey and State Geologist. His research interests stress the geological applications of geophysics and span a variety of techniques at a variety of scales. He, his students, and colleagues have conducted many studies of the structure and evolution of the crust using gravity, magnetic, remote sensing, and seismic measurements integrated with geological data, often as part of large international cooperative efforts.