INVESTIGADORES
GUIDO Diego Martin
artículos
Título:
Diverse subaerial and sublacustrine hot spring settings of the Cerro Negro epithermal system (Jurassic, Deseado Massif), Patagonia, Argentina
Autor/es:
GUIDO, D.; CAMPBELL, K.
Revista:
JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH
Editorial:
ELSEVIER SCIENCE BV
Referencias:
Lugar: Amsterdam; Año: 2012 vol. 229 p. 1 - 12
ISSN:
0377-0273
Resumen:
The Late Jurassic (~150
Ma) Cerro Negro volcanic-epithermal-geothermal system (~15 km2 area),
Deseado Massif, Patagonia, Argentina, includes two inferred volcanic emission
centers characterized by rhyolitic domes
linked along NW-SE regional faults that are associated with deeper level Au/Ag
mineralization to the NW, and with shallow epithermal quartz veins and mainly
travertine surface hot spring manifestations to the SE. Some travertines are
silica-replaced, and siliceous and mixed silica-carbonate geothermal deposits
also are found. Five hot spring-related
facies associations were mapped in detail, which show morphological and
textural similarities to PleistoceneRecent geothermal deposits at Yellowstone
National Park (U.S.A.), the Kenya Rift Valley, and elsewhere. They are interpreted to represent subaerial travertine fissure
ridge/mound deposits (low-flow spring discharge) and apron terraces (high-flow spring
discharge), as well as mixed silica-carbonate lake margin and shallow lake
terrace vent-conduit tubes, stromatolitic mounds, and volcano-shaped cones. The nearly 200 mapped fossil vent-associated
deposits at Cerro Negro are on a geographical and numerical scale comparable
with subaerial and sublacustrine hydrothermal vents at Mammoth Hot Springs, and
affiliated with Yellowstone Lake, respectively. Overall,
the Cerro Negro geothermal system yields paleoenvironmentally significant
textural details of variable quality, owing to both the differential
preservation potential of particular subaerial versus subaqueous facies, as
well as to the timing and extent of carbonate diagenesis and silica replacement
of some deposits. For example, the western
fault associated with the Eureka epithermal quartz vein facilitated early
silicification of the travertine deposits in the SE volcanic emission center,
thereby preserving high-quality, microbial macro- and micro-textures of this
silica-replaced pseudosinter. Cerro
Negro provides an opportunity to reconstruct paleogeographic, paleohydrologic
and paleoenvironmental associations in a well-exposed, extensive and diverse
fossil geothermal system. This Late Jurassic hydrothermal deposit will likely
contribute to a better understanding of the impact of depositional and
post-depositional history on the development and long-term preservation
potential of Lagerstätte in epithermal settings and, more generally, in extreme
environments of the geological record.