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Task 50 - deposition of lignites in the Fort Union Group and related strata of the northern Great Plains

Description: Late Cretaceous, Paleocene, and early Eocene geologic and paleontologic studies were undertaken in western North Dakota, eastern and south-central Montana, and northwestern and northeastern Wyoming. These study areas comprise the Williston, Bighorn, and Powder River Basins, all of which contain significant lignite resources. Research was undertaken in these basins because they have the best geologic sections and fossil record for the development of a chronostratigraphic (time-rock) framework for the correlation of lignite beds and other economic resources. A thorough understanding of the precise geologic age of the deposition of sediments permits a powerful means of interpreting the record of geologic events across the northern Great Plains. Such an understanding allows for rigorous interpretation of paleoenviromnents and estimates of resource potential and quality in this area of economically significant deposits. This work is part of ongoing research to document change in the composition of molluscan fossil faunas to provide a paleoenvironmentally sensitive independent means of interpreting time intervals of brief duration during the Late Cretaceous, Paleocene, and Eocene. This study focuses on the record of mollusks and, to a lesser extent, mammals in the (1) Hell Creek-Tullock Formations, which include the Cretaceous-Paleocene boundary, in the western portion of the Williston Basin, Montana; (2) uppermost Cretaceous, Paleocene, and lowermost Eocene strata in western North Dakota, which -includes the last interior seaway in North Dakota; (3) upper Paleocene and lowermost Eocene of the northern portion of the Bighorn Basin of south-central Montana and northwestern Wyoming; and (4) Powder River Basin of northeastern Wyoming and southeastern Montana. The geologic record provides different physical and paleontological information to aid in interpreting the geologic record through the study interval.
Date: August 11, 1997
Creator: Hartman, J.H.; Roth, B. & Kihm, A.J.
Partner: UNT Libraries Government Documents Department

KUCHEN: An experiment to evaluate decoupling in high-aspect-ratio cavities

Description: It has been argued that even if cavity-decoupled nuclear explosions are a theoretical evasion scenario, the size of the cavity required may be so large as to preclude their use, except possibly in salt. For example, to obtain a decoupling factor of 50 or more would require a cavity radius of at least 20 m/kt. Various theoretical studies have shown, however, that spherical cavities may not be necessary, and that ratios of length-to-span of 10-20 might be used without significant loss of decoupling capability so long as the volume is maintained. This means, for example, that if a tunnel with cylindrical cross section were employed to decouple a 1 kt explosion, the tunnel radius would decrease from 20 m to 8.1 m with an aspect (length-to-diameter) ratio of 10 and to 6.4 m with an aspect ratio of 20. At NTS, we intend to take advantage of the readiness effort activities and funding to perform mid-scale chemical-explosion decoupling experiments in an event called KUCHEN that is scheduled for the spring of 1995. We have identified an 8 ft-diameter hole, 3 50 ft deep in area 9 (U9cu) that is available for these experiments. Our plan is to conduct two tamped shots and at least one decoupling shot in this hole. The explosive charge will be on the order of 50 kg and the aspect ratio will be in the range 10-15. Details of the proposed experiments are discussed.
Date: January 1, 1995
Creator: Glenn, L.A.; Heinle, R.A.; Moran, B.; Rambo, J. & Roth, B.G.
Partner: UNT Libraries Government Documents Department