Shrimp U-Pb Geochronology Final Report
Abstract
This report presents SHRIMP zircon U-Pb analyses from the Sierras septentrionales
de Córdoba, Sierras de San Luis y Comechingones and the Sierras de Chepes y las
Minas areas. Location details, petrographic descriptions and whole rock
geochemical analyses are reported separately by Stuart-Smith and others (1996),
Sims and others (1996) and Lyons and others (1996), respectively. Geological
interpretations of rocks pertaining to this study are to be found in the 1:250 000 sheet
reports.
The Geoscientific Mapping of the Sierras Pampeanas is a cooperative project
between the Australian Geological Survey Organisation (AGSO) and the Dirección
Nacional del Servicio Geológico (DNSG) of the Subsecretaría de Minería, funded by
the Government of the Argentine Republic. As a pilot second generation mapping
program, the project aims to update the geoscientific knowledge base, provide a
modern framework for resource assesment, and promote exploration and
development in the region.
The project covers three separate areas totalling 27 000 square kilometres in the
southern part of the Sierras Pampeanas, Argentina where basement Precambrian to
Palaeozoic metamorphics and granites crop out on the eastern margin of the Andean
Mobile Belt. The area, best known for its production of industrial and construction
materials also contains metallic deposits. Mineral resources include gold and
polymetallic (Au, Ag, Pb, and Zn) vein deposits with past production of tungsten,
bismuth, tin, manganese, and chromium. The three areas were selected to provide
key information on their geology and mineral potential through the application of
integrated geophysical/ geological mapping and metallogenic analysis and to
provide a continuous section of the major tectonostratigraphic packages comprising
the southern Sierras Pampeanas.
As part of the Work Program, geochronological analyses, using SHRIMP U-Pb, ArAr
and Rb-Sr techniques of selected samples were undertaken. The aim of the
geochronological program is to provide key data to establish the timing of igneous
rock crystallisation, major metamorphic/ deformation episodes, and mineralising
events. The data would also allow independent correlation of metamorphic rock
packages with numerical age control, assisting geological mapping of the project
area, and providing an important database and framework for tectonic
interpretation of the Sierras Pampeanas. This report focuses on the SHRIMP U-Pb
results.
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Camacho, A.; Ireland, MSc y Ireland, T.R., 1997. Shrimp U-Pb Geochronology Final Report. Geoscientific Mapping of the Sierras Pampeanas, Argentine-Australian Cooperative Project. Publicación;164. Buenos Aires, Australian Geological Survey Organisation
Fil: Ireland, MSc. Australian Geological Survey Organisation; Australia.
Fil: Camacho, A. Servicio Geológico Minero Argentino; Argentina.
Fil: Ireland, T.R. Australian Geological Survey Organisation y The Australian National University. Research School of Earth Sciences; Australia.