SEDIMENTOLOGY / STRATIGRAPHY

Dr. David B. Loope

Ph.D. 1981, University of Wyoming


Research Interests

Most of my research has involved wind-blown sediments on the Great Plains (Quaternary) and on the Colorado Plateau (Pennsylvanian through Jurassic). My "rock" projects are focused on the Navajo and Entrada Sandstones in southern Utah. Clint Rowe and I used dip directions of the cross-strata in the Navajo in our attempt to figure out atmospheric circulation over the supercontinent Pangea during the Early Jurassic. Steep cross-strata in the Navajo that formed by dry avalanching down dune slip faces contain abundant dinosaur tracks. As these animals crossed the dunes, they generated avalanches, and then stepped on them.

Most recently, Dick Kettler, Karrie Weber, and I have been working on the iron-oxide-cemented concretions and banding in the Navajo Sandstone (Jurassic of southern Utah), the Dakota Formation (Cretaceous of eastern Nebraska), and the Umm Ishrin Formation (Cambrian of southern Jordan and Egypt). And Derek Burgess just finished his M.S. on the Shinarump Member of the Chinle Formation (Triassic of southern Utah and northern Arizona). We think the iron oxide structures are the altered remnants of precursor siderite concretions that formed in association with ancient carbon dioxide reservoirs. The oxidation of siderite took place relatively recently, during the Neogene uplift of the Colorado Plateau and the eastern margin of the Red Sea Rift. These diagenetic features tell very interesting hydrogeologic, geomorphic, and geomicrobiological stories.

The Nebraska Sand Hills cover nearly one fourth of the state of Nebraska and provide some "ground truth" for interpretations of ancient wind-blown sandstones. More important, however, is their record of Quaternary climate change on the Great Plains. Recent work has shown that most of this giant dunefield--including bedforms up to 400 feet high--was active only a few thousand years ago. Jim Swinehart, recently retired from the Conservation and Survey Division of University of Nebraska, Joe Mason my students, and I have been studying the interactions of streams, dunes, and lakes on the Great Plains during the latest Pleistocene and the Holocene. The UNL Luminescence Geochronology Lab in the basement of Bessey Hall (supervised by Ron Goble and Paul Hanson) has been a real stimulus to our work in the Sand Hills. New OSL dates come directly from eolian deposits; we no longer have to rely on dating buried carbon-rich soils or peats for our chronology of drought events.

 


Selected Research Publications (click on title for PDF)

Articles for a Broader Audience

Google Scholar Profile

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