B. Athabasca Basin: EXTECH IV Papers

Transcription

1 B. Athabasca Basin: EXTECH IV Papers Saskatchewan Geological Survey 9i

2 98 Summory of Investigations](!()(}, J 'o/ume :!

3 EXTECH IV - Athabasca Uranium Multidisciplinary Study - Overview C. W Jefferson I and G.D. Delaney This section of the Summary of Investigations reports on preliminary results from the first field season of the EXTECH IV Athabasca Uranium Multidisciplinary Study, a collaborative three year study of the Athabasca Basin and its uranium deposits. This is the fourth in a series of EXploration TECHnology projects undertaken by Natural Resources Canada and various partners. In addition to NRCan, represented by the Geological Survey of Canada (GSC). other funding partners are Saskatchewan Energy and Mines (SEM), Cameco Corporation, COG EMA Resources Inc., and Alberta Geological Survey (AGS). The research team also includes the Saskatchewan Researc h Council (SRC) as well as scientists from the universities of Regina, Saskatchewan, and Laurentian. EXTECH IV is coordinated by Dan Brisbin (Cameco), Gary Delaney (SEM), Charlie Jefferson (GSC), Ph ilippe Portella (COG EMA), and Reg O lson (Alberta Geological Survey). There are two main objectives to this investigation: l) to improve understanding of the Athabasca Basin and the context of its uranium deposits, and 2) to develop new techno logies for exploring for uranium, particularly in the deeper part of the basin. A key goal of this work is to maintain the Athabasca Basin as the most attractive place in the world to explore for and mine uranium. Currently the Athabasca Bas in produces 32% of the world's uranium. EXTECH IV comprises eight different sub-projects involving over two dozen researchers. A list o f sub-projects, goals, and prog ress to-date in point form is provided below. Aspects of some of these investigations are highlighted in the papers that fo llow. Sub-project 1: High-resolution Seismic Reflection Survey Co-leaders: Zoli Hajnal (University of Saskatchewan) and Don White (Geological Survey of Canada) Goal: To develop a viable seismic reflection survey technique for deep mineral exploration, and contribute to a 4-D geoscience framework for mineral exploration in the Athabasca Basin. Work f'lan: This project will entail a high-resolution, pseudo 3-D. seismic reflection survey across the McArthur Ri ver orebody. Prelim inary seismic modeling has been done for the planned field survey area (Hajnal el al., this volume). New data from borehole geophysics from summer 2000 (sub-project 2. Mwenifumbo et al.. this volume) is being incorporated in the models. Reassessment of the Athabasca extension to 1994 LITHOPROBE line S2b, in Points North area, indicates a different interpretation of stratigraphic and unconformity picks, but reaffirms the potential usefulness of highrcso lution seismic data for both stratigraphy, basement topography, and structures transecting Athabasca Group and/or basement. Significant local relief on the basal unconformity requires use of litho logic logs from drill ho les that are located within I km or less of the line. Ground-truthing and datum re-definition are in progress. Sub-project 2: Multiparamcter Borehole Geophysics Leader: Jonathan Mwcnifumbo (Geological Survey of Canada) Goal: To enhance existing, and develop new, exploration technologies and strategies by improving knowledge of a complete spectrum of bu lk geophysical characteristics of the Athabasca uranium deposits and their host rocks. Work Plan: Characterize in situ acoustic, electrical. radioelement, thermal, and geotechnical/geophysical parameters o f the uranium deposits and associated lithologic units and alteration. ' (icologirnl Survey ottana<la. 60 I Booth Street. Ottawa. ON!-.: IA OUC Saskmchewa11 Geolo~lcaf S111Tey S/9

4 Multi-sensor geophysical measurements including spectrometric natural gamma-ray, spectral gamma-gamma density, full wavefonn sonic, magnetic susceptibility, inductive conductivity, resistivity, and induced polarization were made in two boreholes at each of Shea Creek and McArthur River sites (Mwenifumbo et al., this volume). Litho logy and uranium mineralization with associated alteratio n can be readily mapped by several of the geophysical parameters, correlate directly with geological logs, and offer new tools for stratigraphic correlation within the Athabasca Basin, facilitated by GSC's Log View geophysical plotting software. Heavy duty plastic casing preserves drill ho les for geophysical logging and pennits most parameters to be measured. In situ physical rock properties, such as compressional-wave velocities and densities, are providing necessary infonnation to help design the high-resolution seismic survey and to interpret resulting data that will be acquired within the Athabasca Basin. Sub-project 3: Bitumens, Hydrocarbons, Fluids, and Diagenesis Leader: Lavern Stasiuk (Geological Survey of Canada) Goal: To evaluate the origin and possible influence of bitumens/hydrocarbons associated with the uranium mineralization. Work Plan: To undertake a regional study of the organic geochemistry of the Athabasca sandstones and detailed investigations of the organic geochemistry and petrography of bitumen-rich zones associated with uranium mineralization. Established protocol for handling, preparation, and analys is of NORM (Naturally Occurring Radioactive Materials) using an external consultant and the Canadian Nuclear Safety Commission. Seventy-five sandstone and potential hydrocarbon source rock samples were collected from th ree boreholes within the Athabasca Basin: Rumple Lake 74-J, Cluff Lake Car- I I 4. and Am ok Car-I 81. Twenty-five doubly polished thin sections are in preparation for aqueous fluid inclusion microthermometry and paragenetic evaluation of the Locker Lake Fonnation. RockEval system bulk organic geochemistry analyses were completed on 49 potential hydrocarbon source rock samples from Amok Car- I 81, including% Total Organic Carbon, Tmax). Fi fty-one polished samples were prepared for organic petrology-microscopy from potential hydrocarbon sources from Douglas F onnation in Car- I 81. Fluorescence and microspectrometric analyses were completed for 20 samples from Doug las Formation in Carl 81. Twelve samples were collected by EXTECH colleagues from McArthur River site. Athabasca Basin samples, reports, etc. were compiled at GSC Ottawa and GSC Calgary; a database was established and input status brought up to date. Fifteen archived polished thin sections from V. Ruzicka' s collection were selected for re-examination. Excellent Post-doctoral Fellowship (PDF) candidates are being investigated for this project, however, it is a challenge to attract them at traditional PDF salaries in Canadian institutions. Sub-project 4: Athabasca Stratigraphy and Sedimentology Co-leaders: Charlie Jefferson (Geological Survey of Canada) and Gary Yeo (Saskatchewan Energy and Mines) Goal: Refine understanding of Athabasca stratigraphy and sedimentology and their relationships to uranium mineralization. Work Plan: Characterize depositional facies architecture, sequence stratigraphy, provenance, and diagenesis for the Athabasca Group by logging diamond drill core selected to construct a series of transects across the bas in. More than 30 drill ho les were logged in five transects of the eastern part of the basin (Yeo et. al, this volume). /()() Summary of/11vestigations 2000, J'o/ume 2

5 In northeastern transects, basal members are rich in detrital magnetite and thicken westward. In southeastern transects, eastern facies resemble those in open pits whereas western basal facies are distinctive red mudstones and conglomerates. The four-member subdivision of Manitou Falls Formation (MF a, MFb, MFc, and MFd), established by Ramaekers in the 1980s, remains widely applicable and represents an overall fin ing-upward sequence amenable to quantitative description by parameters such as grain size, cross-bed thickness, sorting, and abundance of clay. Prelim inary detailed subdivisions of each member of the Manitou Falls Formation have been suggested by quantitative plots using GSC 's LogView software. Stratigraphic studies are being integrated with borehole geophysics and high-resolution seismic, allowing crosscalibration and improved interpretation of all three. These studies will enhance practical and theoretical exploration models, to improve precision of drilling and interpretation of exploration holes. Sub-project 4a: Detailed Stratigraphic Studies in Athabasca Basin Co-leaders: Darrel Long (Laurentian University) and Gary Yeo (Saskatchewan Energy and Mines) Goal: To improve understanding of Athabasca stratigraphy and sedimentology and its role in the localization of uranium mineralization at some of the major uranium deposits. Work Plan: To undertake detailed investigations of fac ies relationships in the basal Manitou Fall s Formation as revealed in open pits and areas of relatively good exposure. Progress To-date. Detailed investigations of stratigraphic relationships in Manitou Falls Formation in the Sue C Pit at McClean Lake and the Deilmann Pit at Key Lake (Long et al, this volume). Basal strata exposed in Sue and Key Lake Pits include two conglomeratic coarse sandstones separated by a stepped erosional surface and a basal conglomerate respectively. Sub-project 5: Basement to Western Athabasca Basin Goal: To better understand the basement geology of the western Athabasca Basin and its influence on mineralization. Work f'lan: Augment an earlier study of the sub-athabasca basement geology and geochemistry by integrating geophysical data with the logging of selected drill core supported by geochronological and geochemical studies. Correlate with infonnation about flanking shield rocks. Progress To-dale: This sub-project is scheduled to commence in year two of EXTECH JV. Sub-project Sa: Detailed Structural Studies of Athabasca Uranium Deposits Leader: Ghislain Tourigny (Saskatchewan Energy and Mines) Goal: To understand the structural history of the basement/cover rocks at some of the major uranium deposits and the role of structure in the local ization of uranium mineralization. Work Plan: To undertake detailed structu ral investigations in open pits at some of the deposits and to integrate this work with that of the broader sub-athabasca basement study. Detailed studies in Sue C (McClean Lake) and Deilmann (Key Lake) pits have demonstrated compatibility wi th structural styles established in previous regional projects and provided a detailed understanding of the structural context of these two ore deposits (Tourigny et al., this volume; Harvey and Bethune, this volume). Sub-project 6: Gamma Ray Geophysics Leader: Rob Shives (Geological Survey of Canada) Goal: To improve understanding of current regional radiometric data over the Athabasca Basin and evaluate its relevance to mineralogical alteration and other components of the project. Sm katchewan Geological Survey IOI

6 Work Plan: Conversion of previous regional and detailed analogue NA TGAM gamma-ray spectrometer surveys to digital data and subsequent recompilation and reinterpretation. This will be supported by detailed ground surveys in specific areas. A brief field study in the McArthur River Mine area tested the hypothesis that gamma ray spectrometry can map radioactive element (K, eu, and eth) variations associated with known illite enrichment in sandstone boulders (Shives et al., this volume). Preliminary results indicate that ground spectrometry can provide cost-effective, in situ determination of potassium enrichment related to illite within sandstone boulders. Detailed airborne high-sensitivity gamma ray spectrometric surveys would identify differences in low eth/k ratios, thereby providing exploration guidance. Sub-project 6a: Surficial Geology Co-leaders: Janet Campbell (Saskatchewan Research Council) and Rod Klassen (Geological Survey of Canada) Goal: To establish a surficial geological framework for the Athabasca Basin to aid in mineral exploration and sustainable development. Work Plan: Compilation of available Quaternary geological data for the NEA-IAEA test area in both digital database and map formats with follow up ground studies of selected areas to ground truth surficial relationships. Saskatchewan Research Council initiated digital compilation and upgrading of existing and limited new data on surficial geology and regional till geochemistry in the NEA-IAEA test area, where a previous jointly sponsored GSC-SEM program compared different methods of exploration for uranium. Eleven bulk till samples and field data were collected from sites along the Black Lake and Points North roads from a variety of till deposits with background and elevated total count airborne radiometric data (Campbell and Shives et al., this volume). Compositional analyses will assist with ground calibration of the radiometric data. Sub-project 7: Clay Mineral Studies Leader: Jeanne Percival (Geological Survey of Canada) Goal: To undertake investigations of the genesis of clay minerals in the pre-athabasca regolith, Athabasca Group sandstones, and alteration haloes surrounding ore bodies so as to enhance the interpretation of stratigraphy, diagenesis, basement geology, gamma ray geophysics, and surficial geology. Work Plan: Petrographic and geochemical analysis of clay minerals from regional stratigraphic and deposit-scale sample suites. Participated in core logging, sampling, processing of samples for polished thin sections, and clay-size separations co-ordinated with stratigraphic studies. Synchrotron study of uranium associated with illitic clays from the alteration halo around the Cigar Lake uranium deposit, is contributing to understanding of clays in Athabasca Basin and to design follow-up EXTECH studies on clay mineralogy. The new data are being used to assess whether U occurs as U0 2, is adsorbed onto the clay surface, or occurs within the illite interlayer in the alteration halo (Percival et al., this volume). Sub-project 8: Coordination Co-leaders: Charlie Jefferson (Geological Survey of Canada) and Gary Delaney (Saskatchewan Energy and Mines) Goal: Ensure co-operation, transparency, integration, timely delivery, and maximum impact of relevant results. Work Plan: To plan and coordinate field activities, and the subsequent compilation and communication of scientific results. I 02 Summary of lnvesligations 2000, 1 'ofume 2

7 Progress Tu-date: Coordinators ensured full cooperation of staff in all supporting organizations, and smoothed logistics for the many activities involved (staff accommodation, transportation, core logging, sampl ing, mapping, processing of samples, etc.). Communication plans were developed and implemented, including newspaper, newsletter and government publications, posters, and a Web-site (nearing completion), workshop, and Open House plans. Co-ordinators managed and accounted for cash and in-kind contributions of their respective sponsoring agencies. Sub-project 8a: GIS Database Leader: Bill Slimmon (Saskatchewan Energy and Mines) Goal: Design and compile an Arc View GIS database of all project results including mapping, locations of diamond drill holes, mineral occurrences, assessment work, sections measured, seismic lines, borehole geophysics, gamma ray geophysics, etc. Work Plan: To systematically develop as complete a GlS database as possible, beginning in year one with public domain data and incrementing in years two to three with project-generated data. An extensive GIS database, compiling previous work, is being constructed in Arc View. Data entry and analysis are ongoing, and the database is available for query by project participants through distribution of CD-ROM copies on request. Saska1chewan Geolog ical Survey /03

8