Publications
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Preliminary map showing quaternary faults and landslides in the Cliff Lake 15' quadrangle, Madison County, Montana
No abstract available.
Authors
J. M. O'Neill, T. H. LeRoy, Paul E. Carrara
New uranium-series ages of the Waimanalo Limestone, Oahu, Hawaii: implications for sea level during the last interglacial period
The Waimanalo Formation (limestone) of Oahu has been correlated with the last interglacial period based on U-series dating of corals by T.-L. Ku and colleagues. The limestone consists of growth-position corals and overlying coral conglomerate. An apparent bimodal distribution of ages for the growth-position corals (mean age = 133 ka) and the overlying coral conglomerate (mean age = 119 ka) has bee
Authors
D.R. Muhs, B. J. Szabo
U-Pb provenance ages of shocked zircons from the K-T boundary, Raton Basin, Colorado
No abstract available.
Authors
Wayne R. Premo, G. A. Izett
Precise U‐Pb ages of Duluth Complex and related mafic intrusions, northeastern Minnesota: Geochronological insights to physical, petrogenetic, paleomagnetic, and tectonomagmatic processes associated with the 1.1 Ga Midcontinent Rift System
Precise resolution of the timing of igneous activity is crucial to understanding the dynamic processes associated with continental rifting. Mafic intrusive rocks constitute a major portion of the exposed 1100 Ma (Keweenawan) Midcontinent Rift system in northeastern Minnesota; however, prior to this study, geochronological data were insufficient to allow rigorous interpretation of intrusive histori
Authors
James B. Paces, James D. Miller
Effects of hydrothermal alteration on the magnetization of the Oligocene Carpenter Ridge Tuff, Bachelor Caldera, San Juan Mountains, Colorado
Intracaldera Oligocene Carpenter Ridge Tuff fills the Bachelor caldera in the central San Juan caldera complex and hosts mineral deposits of the Creede mineral district. The Carpenter Ridge Tuff and unaltered portions of its intracaldera Bachelor Mountain Member, have strong, high‐coercivity, reverse magnetizations with average magnetic susceptibility (MS) and natural remanent magnetization (NRM)
Authors
Donald S. Sweetkind, Richard L. Reynolds, David A. Sawyer, Joseph G. Rosenbaum
Paleo-oceanographic cycles and events during the Late Cretaceous in the Western Interior Seaway of North America
No abstract available.
Authors
L.M. Pratt, M.A. Arthur, Walter E. Dean, Peter A. Scholle
Stable carbon and oxygen isotope studies of the sediments of Elk Lake, Minnesota
Variations in the ratios of 18O:16O and 13C:12C in calcite throughout the Holocene in Elk Lake, Minnesota, are recorded in three varve-calibrated carbonate cores. Marl in a varved deep-basin (29.6 m) core consists mainly of calcite precipitated from surface waters during the summer and probably provides the least complicated isotope record. Marl in a sublittoral (10 m) core consists of calcite con
Authors
Walter E. Dean, Minze Stuiver
Modern sedimentation in Elk Lake, Clearwater County, Minnesota
The varved sediments of Elk Lake, Clearwater County, Minnesota, contain a 10,000 year record of climatic and limnologic events. Sediment traps deployed in the lake’s water column from 1979 to 1981 and from 1983 to 1984 collected samples that permitted us to identify materials, to see the timing of sedimentation events, and to deduce processes that form the microlaminae within varves. Fall and spri
Authors
E.B. Nuhfer, R.Y. Anderson, J. Platt Bradbury, Walter E. Dean
Chronology of Elk Lake sediments: Coring, sampling, and time-series construction
A 22 m series of cores from a continuously laminated sequence of postglacial sediment was recovered from 29.6 m of water from the deepest part of Elk Lake, Clearwater County, Minnesota, by piston and freeze-coring methods during the winters of 1978 and 1982. A varve time series constructed and used as a basis for subsampling the cores and samples, based on the varve chronology, allows precise dete
Authors
R.Y. Anderson, J. Platt Bradbury, Walter E. Dean, Minze Stuiver
Geochemistry of surface sediments of Minnesota lakes
Analyses of 36 trace, minor, and major elements were used to classify the sediments of 46 Minnesota lakes. Q-mode factor analyses grouped Minnesota lake sediments according to clastic-, carbonate-, organic-, and redox-related elements. Carbonate lakes occur in west-central Minnesota; their sediments have relatively high concentrations of CaCO3, Ba, and Sr. Lakes with sediments containing more than
Authors
Walter E. Dean, Eville Gorham, Dalway J. Swaine
Holocene climatic and limnologic history of the north-central United States as recorded in the varved sediments of Elk Lake, Minnesota: A synthesis
Integration of the results and interpretations of geochemical, paleoecological, and sedimentological analyses of a varved sediment record provides a detailed chronicle of limnological and climatic changes for the past 10 ka at Elk Lake, west-central Minnesota. The early Holocene record at Elk Lake was controlled by circumstances of glacial history (e.g., basin morphometry and surrounding till lith
Authors
J. Platt Bradbury, Walter E. Dean, R.Y. Anderson
Elk Lake in perspective
Elk Lake is located in the forested region of north-central Minnesota at the headwaters of the Mississippi River and occupies one of countless basins left behind as the last great Pleistocene ice sheet retreated northward into Canada. In this respect it resembles many other moderately deep, dimictic, hard-water lakes in the north-central United States, the sediments of which contain a history of p
Authors
R.Y. Anderson, Walter E. Dean, J. Platt Bradbury