Conference Papers
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Browse almost 5,000 conference papers authored by our scientists and refine search by topic, location, year, and advanced search.
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Velocity mapping in the Lower Congo River: A first look at the unique bathymetry and hydrodynamics of Bulu Reach
The lower Congo River is one of the deepest, most powerful, and most biologically diverse stretches of river on Earth. The river’s 270 m decent from Malebo Pool though the gorges of the Crystal Mountains to the Atlantic Ocean (498 km downstream) is riddled with rapids, cataracts, and deep pools. Much of the lower Congo is a mystery from a hydraulics perspective. However, this stretch of the river
Authors
P. Ryan Jackson, Kevin A. Oberg, Ned Gardiner, John Shelton
A deployment of broadband seismic stations in two deep gold mines, South Africa
In-mine seismic networks throughout the TauTona and Mponeng gold mines provide precise locations and seismic source parameters of earthquakes. They also support small-scale experimental projects, including NELSAM (Natural Earthquake Laboratory in South African Mines), which is intended to record, at close hand, seismic rupture of a geologic fault that traverses the project region near the deepest
Authors
Arthur F. McGarr, Margaret S. Boettcher, Jon Peter B. Fletcher, Malcolm J. S. Johnston, R. Durrheim, S. Spottiswoode, A. Milev
Composition and source of salinity of ore-bearing fluids in Cu-Au systems of the Carajás Mineral Province, Brazil
The composition and Cl/Br – NaCl ratios of highly saline aqueous inclusions from large tonnage (> 100 t) IOCG deposits (Sossego, Alvo 118, and Igarapé Bahia) and a Paleoproterozoic intrusion-related Cu-Au-(Mo-W-Bi-Sn) deposit (Breves; < 50 Mt)) in the Carajás Mineral Province have been analysed by LA-ICP-MS and ion chromatography. In both Cu-Au systems, brine inclusions are Ca-dominated (5 to 10 t
Authors
Roberto Xavier, Brian Rusk, Poul Emsbo, Lena Monteiro
Geochemistry and geochronology of carbonate-hosted base metal deposits in the southern Brooks Range, Alaska: Temporal association with VMS deposits and metallogenic implications
The Brooks Range contains enormous accumulations of zinc and copper, either as VMS or sediment-hosted deposits. The Ruby Creek and Omar deposits are Cu-Co stratabound deposits associated with dolomitic breccias. Numerous volcanogenic Cu-Zn (+/-Ag, Au) deposits are situated ~20 km north of the Ruby Creek deposit. The carbonate-hosted deposits consist of chalcopyrite and bornite that fill open space
Authors
Karen Kelly, John Slack, David Selby
Gold deposit styles and placer gold characterisation in northern and east-central Madagascar
Microchemical characterisation of bedrock and placer gold grains from six gold districts within the Archaean domains and intervening Neoproterozoic Anaboriana-Manampotsy belt of northern and east-central Madagascar show few opaque inclusions (e.g pyrrhotite, Bi tellurides) but wide range of Ag contents (40wt%). Some districts exhibit multiple source populations of grains. The ‘greenstone belt’ te
Authors
Peter E. J Pitfield, Michael T. Styles, Cliff D. Taylor, Roger M. Key, Bauer, A Ralison
The source of Witwatersrand gold: Evidence from uraninite chemistry
An in-situ LA-ICP-MS study of different generations of uraninite from the Mesoarchaean Witwatersrand gold palaeoplacer deposits revealed unusually high Au concentrations in rounded, detrital uraninite grains but no detectable Au in secondary, hydrothermally mobilised uraninite. A Au-enriched uraninite-bearing magmatic host is suggested as a significant source for detrital gold in the Witwatersrand
Authors
Hartwig E. Frimmel, Poul Emsbo, Alan E. Koenig
Discharge and other hydraulic measurements for characterizing the hydraulics of Lower Congo River
The first direct measurements of discharge of the Lower Congo River below Malebo Pool and upstream from Kinganga, Democratic Republic of Congo (DRC) were made in July 2008 using acoustic Doppler current profilers, differential GPS, and echo sounders. These measurements were made in support of research that is attempting to understand the distribution of fish species in the Lower Congo River and re
Authors
Kevin Oberg, John M. Shelton, Ned Gardiner, P. Ryan Jackson
Laboratory evaluation of an OTT acoustic digital current meter and a SonTek Laboratory acoustic Doppler velocimeter
Recently, an acoustic current meter known as the OTT * acoustic digital current meter (ADC) was introduced as an alternative instrument for stream gaging measurements. The Bureau of Reclamation and the U.S. Geological Survey collaborated on a side- by-side evaluation of the ADC and a SonTek/YSI acoustic Doppler velocimeter (ADV). Measurements were carried out in a laboratory flume to evaluate the
Authors
T.B. Vermeyen, Kevin A. Oberg, Patrick Ryan Jackson
The effect of channel shape, bed morphology, and shipwrecks on flow velocities in the Upper St. Clair River
In the Great Lakes of North America, the St. Clair River is the major outlet of Lake Huron and conveys water to Lake St. Clair which then flows to Lake Erie. One major topic of interest is morphological change in the St. Clair River and its impact on water levels in the Upper Great Lakes and connecting channel flows. A combined multibeam echosounder (MBES) bathymetric survey and acoustic Doppler c
Authors
Jonathan A. Czuba, Kevin Oberg, Jim Best, Daniel R. Parsons
Using a StreamPro acoustic doppler current profiler in moving-bed conditions: Problems and solutions
No abstract available.
Authors
David S. Mueller, Mike S. Rehmel, Chad R. Wagner
Use of multi-temporal Landsat images to monitor forest disturbance (1987-2007) in the Black Hills of South Dakota
Monitoring forest disturbance is important for studying carbon pools and fluxes. The goal of this study is to observe forest disturbance of different burn severity levels using multi-temporal Landsat images. The Jasper Fire occurred in the Black Hills National Forest, South Dakota, during August and September of 2000. The fire disturbance to ecosystem characteristics has a widespread and long-term
Authors
Xuexia Chen, Donald O. Ohlen
Vegetation change detection and quantification: linking Landsat imagery and LIDAR data
Measurements of the horizontal and vertical structure of vegetation are helpful for detecting and monitoring change or disturbance on the landscape. Lidar has a unique ability to capture the three-dimensional structure of vegetation canopies. In this preliminary study, we present the results of a series of exploratory data analyses that tested our assumptions about the links between the structural
Authors
Birgit E. Peterson, Kurtis J. Nelson