RP - RESEARCH PROGRAM: USGSOP (Non-USGS publications with USGS authors)
CP - COUNTRY OF PUBLICATION: Netherlands
PY - PUBLICATION YEAR: 1994
LA - LANGUAGE: English
AB - ABSTRACT: More than 20 eruptive events during the 1989-1990 eruption of Redoubt Volcano emplaced a complex sequence of lithic pyroclastic-flow, -surge, -fall, ice-diamict, and lahar deposits mainly on the north side of the volcano. The deposits record the changing eruption dynamics from initial gas-rich vent-clearing explosions to episodic gas-poor lava-dome extrusions and failures. The repeated dome failures produced lithic pyroclastic flows that mixed with snow and glacial ice to generate lahars that were channelled off Drift glacier into the Drift River valley. Some of the dome failures occurred without precursory seismic warning and appeared to result solely from gravitational instability. Material from the disrupted lava domes avalanched down a steep, partly ice-filled canyon incised on the north flank of the volcano and came to rest on the heavily crevassed surface of the piedmont lobe of Drift glacier. Most dome-collapse events resulted in single, monolithologic, massive to reversely graded, medium- to coarse-grained, sandy pyroclastic-flow deposits containing abundant dense dome clasts. These deposits vary in thickness, grain size, and texture depending on distance from the vent and local topography; deposits are finer and better sorted down flow, thinner and finer on hummocks, and thicker and coarser where ponded in channels cut through the glacial ice. The initial vent-clearing explosions emplaced unusual deposits of glacial ice, snow, and rock in a frozen matrix on the north and south flanks of the volcano. Similar deposits were described at Nevado del Ruiz, Colombia and have probably been emplaced at other snow-and-ice-clad volcanoes, but poor preservation makes them difficult to recognize in the geologic record. In a like fashion, most deposits from the 1989-1990 eruption of Redoubt Volcano may be difficult to recognize and interpret in the future because they were emplaced in an environment where glacio-fluvial processes dominate and quickly obscure the primary depositional record.
RF - REFERENCE SOURCE: GeoRef, Copyright 2000, American Geological Institute.
CO - CODEN: #03249
AN - ACCESSION NUMBER: 1997-035686
UD - UPDATE CODE: 199712
Registro 4998 de 5614 - GeoRef Disc 4: 1993-1996
TI - TITLE: Campos gigantes de finales de los 80 asociados con subduccion tipo "A" en Suramerica
Translated Title: Giant fields of the late 1980s associated with A-type subduction in South America.
AU - AUTHORS: Duval-Bernard; Cramez-Carlos; Valdes-Gustavo
AF - AUTHOR AFFILIATION: Total, Caracas, Venezuela
SO - SOURCE: Boletin de la Sociedad Venezolana de Geologos. 19; 1-2, Pages 20-40. 1994.
PB - PUBLISHER: Sociedad Venezolana de Geologos. Caracas, Venezuela. 1994.
CP - COUNTRY OF PUBLICATION: Venezuela
PY - PUBLICATION YEAR: 1994
LA - LANGUAGE: Spanish
LS - LANGUAGE OF SUMMARY: English
AB - ABSTRACT: The Cano Limon, Guafita, Ceuta-Tomoporo, El Furrial y Cusiana giant fields were discovered in the northern region of South America at the end the of 80's. It has been proved that all hydrocarbon accumulated in those fields was generated by the same source rock (shaly-calcareous transgressive sediments associated to the prograded basal surface of the post-Pangea first order eustatic cycle). Although the present context for these fields is associated to a foredeep, the petroliferous systems of Cano Limon, Guafita, Ceuta-Tomoporo and Cusiana are associated to a geological environment of ancient basins inside the arc while El Furrial is associated to an ancient divergent margin. For the first three mentioned fields the most promising features for a successful exploratory campaign are the presence of reactivated ancient faults of high angle and the proximity to ancient structural highs. In the case of El Furrial, the overpressured seals, the efficient lateral ramps and the recent structural highs are the key features.