Tesis Doctoral Ramiro Lopez (2006)

ABSTRACT
This research work was made with the aim of getting the geology oriented Natural Science Doctor
degree, equivalent to a PhD degree, in the Facultad de Ciencias Naturales y Museo (La Plata National
University). The topics developed were chosen to get the author specific orientation in ore geology and
volcanic successions research.
The thesis work was carried out in the Mineral Resources Institute (INREMI), which belongs to UNLP and
CICBA, with Dr. Isidoro B. Schalamuk as director and Dr. Raúl E. de Barrio as co-director. This institution
is working in the Deseado Massif province since 1994, doing basic and applied research works, mainly
over epithermal mineralization.
This province has a particularly brief history of research mining works. Since the discovery of epithermal
mineralization in the area, three decades ago, different studies were done in the region. The first works
were done by the Secretaría de Minería, especially with the Plan Patagonia, and then by numerous
mining companies. In that sense, the Deseado Massif is a strategic province for Doctoral thesis studies,
which allows through detail work, characterize the volcanism and metallogenesis.
This research was placed in the northwest of the Deseado Massif, in order to main the gap between the
majority of the previous thesis works that were made in the centre and east of the Province. The most
important research work made in the area consists in the de Barrio (1989) thesis, which was focused in
geological and geochemical aspects of Chon Aike Formation 100km south form the present study area.
After the first field works carried out over the main outcrops of the northwest, one of the biggest and well
exposed veins in the Deseado Massif, Eureka vein, was recognized. At the same time, the topographic
differences of at least 50 m, expose well-preserved relationships between the different Jurassic volcanopyroclastic
facies. Those characteristics are excellent to understand the geological and metallogenical
systems developed during the Jurassic in the area.
The unique previous works from this area were carried out by the Argentinean Geological Service
(SEGEMAR), and it was a 1:250,000 scale geological work in the area called “El Pluma” (Cobos y
Panza, 2003). In the other hand, mining companies carried out different prospecting and exploration
works between the 1996-2000 period, leaving the area because of the mining industry fall down in these
years. That is why there was no company for shearing information or directly sponsoring this research.
The objectives planed for this thesis were intimately related to the characterization of the volcanic
succession and the hydrothermal system that took place during the upper Jurassic in the northwestern
Deseado Massif, and its comparison with the rest of the province.
Considering the good outcrops of the area, a strong field-based work was planned. After satellite imagery
processing, a detailed field mapping of the main mineralised structures in the area was done, with specific
instruments (compass, etc.) help.
Several types of samples were taken, taking into account the different analytic techniques carried out in
this research. The petrography, chalcography and fluid inclusions studies were done in the INREMI, the
X-ray difractometry in the Centro de Investigaciones Geológicas (CIG) and the Museo de La Plata, the
rock geochemistry in the Salta (Argentine) and Trieste (Italy) universities, the geochronology and Pb
isotopes in the San Pablo University and the stable isotopes in the Salamanca University.
Lopez, R., 2006. Tesis Doctoral. FCNyM-UNLP.