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Page 7, results 151 - 175

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Geology of the Pennsylvanian and Permian Cutler Group and Permian Kaibab Limestone in the Paradox Basin, southeastern Utah and southwestern Colorado
Steven M. Condon
1997, Bulletin 2000-P
The Cutler Formation is composed of thick, arkosic, alluvial sandstones shed southwestward from the Uncompahgre highlands into the Paradox Basin. Salt tectonism played an important role in deposition of the Cutler in some areas. In the northeast part of the basin, more than 8,000 ft, and as much as 15,000 ft,...
Paleomagnetic and 40Ar/39Ar results from the Grant intrusive breccia and comparison to the Permian Downeys Bluff sill — Evidence for Permian igneous activity at Hicks Dome, southern Illinois Basin
Richard L. Reynolds, Martin B. Goldhaber, Lawrence W. Snee
1997, Bulletin 2094-G
Igneous processes at Hicks dome, a structural upwarp at lat 37.5° N., long 88.4° W. in the southern part of the Illinois Basin, may have thermally affected regional basinal fluid flow and may have provided fluorine for the formation of the Illinois-Kentucky Fluorspar district. The timing of both igneous activity...
Sedimentary carbonate-hosted giant Bayan Obo REE-Fe-Nb ore deposit of Inner Mongolia, China; a cornerstone example for giant polymetallic ore deposits of hydrothermal origin
E. C. T. Chao, J.M. Back, J.A. Minkin, M. Tatsumoto, Wang Junwen, J. E. Conrad, E.H. McKee, Hou Zonglin, Meng Qingrun, Huang Shengguang
1997, Bulletin 2143
Detailed, integrative field and laboratory studies of the textures, structures, chemical characteristics, and isotopically determined ages and signatures of mineralization of the Bayan Obo deposit provided evidence for the origin and characteristics favorable for its formation and parameters necessary for defining giant polymetallic deposits of hydrothermal origin. Bayan Obo is...
Regional diagenetic patterns in the St. Peter Sandstone; implications for brine migration in the Illinois Basin
Janet K. Pitman, Martin B. Goldhaber, Christoph Spoetl
1997, Bulletin 2094-A
Diagenetic minerals and alteration patterns in the Ordovician St. Peter Sandstone, Illinois Basin, record varied hydrologic and chemical conditions during the basin?s long and complex geologic history. Major diagenetic events modifying the St. Peter Sandstone include (1) mechanical compaction, (2) early K-feldspar overgrowth and dolospar precipitation, (3) burial quartz, dolospar, anhydrite, and calcite cementation, and (4) carbonate-cement...
Clastic rocks associated with the Midcontinent rift system in Iowa
Raymond R. Anderson, Robert M. McKay
1997, Bulletin 1989-I
The Middle Proterozoic Midcontinent Rift System (MRS) of North America is a failed rift that formed in response to region-wide stresses about 1,100 Ma. In Iowa, the MRS is buried beneath 2,200?3,500 ft of Paleozoic and Mesozoic sedimentary rocks and Quaternary glaciogenic deposits. An extremely large volume of sediments was...
The Late Triassic bivalve Monotis in accreted terranes of Alaska
Norman J. Silberling, J. A. Grant-Mackie, K. M. Nichols
1997, Bulletin 2151
Late Triassic bivalves of the genus Monotis occur in at least 16 of the lithotectonic terranes and subterranes that together comprise nearly all of Alaska, and they also occur in the Upper Yukon region of Alaska where Triassic strata are regarded as representing non-accretionary North America. On the basis...
Geology of the Harpers Ferry Quadrangle, Virginia, Maryland, and West Virginia
Scott Southworth, David K. Brezinski
1996, Bulletin 2123
The Harpers Ferry quadrangle covers a portion of the northeast-plunging Blue Ridge-South Mountain anticlinorium, a west-verging allochthonous fold complex of the late Paleozoic Alleghanian orogeny. The core of the anticlinorium consists of high-grade paragneisses and granitic gneisses that are related to the Grenville orogeny. These rocks are intruded by Late...
Uranium provinces of North America — Their definition, distribution, and models
Warren Irvin Finch
1996, Bulletin 2141
Uranium resources in North America are principally in unconformity-related, quartz-pebble conglomerate, sandstone, volcanic, and phosphorite types of uranium deposits. Most are concentrated in separate, well-defined metallogenic provinces. Proterozoic quartz-pebble conglomerate and unconformity-related deposits are, respectively, in the Blind River–Elliot Lake (BRELUP) and the Athabasca Basin (ABUP) Uranium Provinces in Canada....
Burial and thermal history of the Paradox Basin, Utah and Colorado, and petroleum potential of the Middle Pennsylvanian Paradox Formation
Vito F. Nuccio, Steven M. Condon
1996, Bulletin 2000-O
The Ismay-Desert Creek interval and Cane Creek cycle of the Alkali Gulch interval of the Middle Pennsylvanian Paradox Formation in the Paradox Basin of Utah and Colorado contain excellent organic-rich source rocks having total organic carbon contents ranging from 0.5 to 11.0 percent. The source rocks in both intervals contain...
Age of the Lospe Formation (early Miocene) and origin of the Santa Maria Basin, California. Petroleum source potential and thermal maturity of the Lospe Formation (lower Miocene) near Point Sal, onshore Santa Maria Basin, California. Obispo Formation, California; remobilized pyroclastic material
Richard G. Stanley, Samuel Y. Johnson, Carl C. Swisher III, Mark A. Mason, John D. Obradovich, Mary Lou Cotton, Mark V. Filewicz, David R. Vork, Mark J. Pawlewicz, Zenon C. Valin, Jean-Luc Schneider, Richard V. Fisher
1996, Bulletin 1995-M,N,O
No abstract available....
Gold placers of the historical Fortymile River region, Alaska
Warren E. Yeend
1996, Bulletin 2125
The Fortymile River region in east-central Alaska has a long and colorful history as the site of the first major gold discovery in interior Alaska. Placer gold has been mined in the region nearly every year since its original discovery in 1886. Total gold production is approximately 500,000 troy ounces....
Chronology of Late Cretaceous igneous and hydrothermal events at the Golden Sunlight gold-silver breccia pipe, southwestern Montana
Ed DeWitt, Eugene E. Foord, Robert E. Zartman, Robert C. Pearson, Fess Foster
1996, Bulletin 2155
Gold mineralization at the Golden Sunlight breccia pipe, southwestern Montana, is related to emplacement of Late Cretaceous alkali-calcic rhyolite and subsequent collapse of the Belt Supergroup wallrock and rhyolite in the pipe. The pipe is inferred to grade downward into an alkalic porphyry molybdenum system. The pipe is cut by...