As karst systems are natural windows to the underground, speleology, combined with geological sur... more As karst systems are natural windows to the underground, speleology, combined with geological surveys, can be useful tools for helping understand the geological evolution of karst areas. In order to enhance the reconstruction of the structural setting in a gypsum karst area (Vena del Gesso, Romagna Apennines), a detailed analysis has been carried out on hypogeal data. Structural features (faults, fractures, tectonic foliations, bedding) have been mapped in the "Grotta del Re Tiberio" cave, in the nearby gypsum quarry tunnels and open pit benches. Five fracture systems and six fault systems have been identified. The fault systems have been further analyzed through stereographic projections and geometric-kinematic evaluations in order to reconstruct the relative chronology of these structures. This analysis led to the detection of two deformation phases. The results permitted linking of the hypogeal data with the surface data both at a local and regional scale. At the local scale, fracture data collected in the underground have been compared with previous authors' surface data coming from the quarry area. The two data sets show a very good correspondence, as every underground fracture system matches with one of the surface fracture system. Moreover, in the cave, a larger number of fractures belonging to each system could be mapped. At the regional scale, the two deformation phases detected can be integrated in the structural setting of the study area, thereby enhancing the tectonic interpretation of the area (e.g., structures belonging to a new deformation phase, not reported before, have been identified underground). The structural detailed hypogeal survey has, thus, provided very useful data, both by integrating the existing information and revealing new data not detected at the surface. In particular, some small structures (e.g., displacement markers and short fractures) are better preserved in the hypogeal environment than on the surface where the outcropping gypsum is more exposed to dissolution and recrystallization. The hypogeal geological survey, therefore, can be considered a powerful tool for integrating the surface and log data in order to enhance the reconstruction of the deformational history and to get a three-dimensional model of the bedrock in karst areas.
Field studies carried out at Longyearbyen (Spitsbergen, 78º 13' N, 15º 36' E) and at Terra Nova B... more Field studies carried out at Longyearbyen (Spitsbergen, 78º 13' N, 15º 36' E) and at Terra Nova Bay (Antarctica, 74° 41' S, 164° 07' E) question the role of frost action as an efficient rock weathering agent. By carrying out measurements of rock temperature, rock moisture content and Young's modulus variations in both locations, differences between these environments are explained in terms of climate, rock properties and the implications of these properties on the weathering processes involved. The large variability of polar environments, and its repercussions on particular geomorphological processes like rock decay, are highlighted.
Geografiska Annaler: Series A, Physical Geography, 2009
ABSTRACT Ice blisters, typically 0.2–0.8 m high and 5–20 m long, develop annually on perennially ... more ABSTRACT Ice blisters, typically 0.2–0.8 m high and 5–20 m long, develop annually on perennially frozen lakes in Northern Victoria Land. They are believed to be caused by hydrostatic pressures generated through progressive freezing of solute-rich water beneath the lake-ice cover during winter. Lake-ice blisters in the study area differfrom icing blisters described from the northern hemisphere. The latter are caused by hydraulic pressures and are found at locations such as river beds or spring sites on sloping terrain. The Antarctic lake-ice blisters reflect the occurrence of dry-based perennially frozen lakes with high salt contents in an extremely cold and arid environment.
... Earth Surface Processes and Landforms 28: 823836. Hall K, André MF. 2006. ... In ICOM Commit... more ... Earth Surface Processes and Landforms 28: 823836. Hall K, André MF. 2006. ... In ICOM Commit-tee for Conservation, 13th Triennial Meeting, Vol. 2, Vontobel R (ed.). James and James: London; 571577. Mattes U, Turner SJ, Larson DW. 2001. ...
... This figure is available in colour online at www.interscience.wiley.com/journal/espl 13 cm/m ... more ... This figure is available in colour online at www.interscience.wiley.com/journal/espl 13 cm/m or 1·3 m/10 m a significantly rough surface. ... Although seem-ingly 'obvious', once stated, it would appear that the comment regarding this scale attribute by Gómez-Heras et al. ...
Herin mine (Champdepraz, Aosta, Italy), located in Aosta Valley, approximately between 1600 and 1... more Herin mine (Champdepraz, Aosta, Italy), located in Aosta Valley, approximately between 1600 and 1800 m a.s.l., was exploited for at least 250 years for its Cu-Fe sulfide ore. The deposit host rocks belong to the metaophiolitic Zermatt- Saas unit, the eclogitic lower portion of the Piedmont Western Alpine Nappe. The ore mineral association mainly comprises pyrite and chalcopyrite, along with other sulfides such as pyrrhotite, sphalerite, cubanite and oxides (magnetite, rutile, ilmenite). The deposit occurs within lenticular massive bodies and thin layers hosted in various greenschist-facies metamorphosed lithotypes. New data on geometric features, mineralogy, mineral chemistry, petrography, minerography were collected and compared with the existing models for massive-sulfide mineral deposits. We suggest a hydrothermal-volcanogenic primary origin of the mineralization with original characteristics largely obliterated by subsequent metamorphic history. On the basis of studies and our results, we identified two parameters as driving criteria for a comprehension of the multistage process that led to the present configuration of the ore: (a) textural characters of pyrite and (b) distribution of selected trace elements (Co, Ni, As) in sulfides. Spot analyses and atomic maps obtained by electron microprobe provided an integration of these two sets of data. Trace elements, in fact, show a zoned distribution, in particular in pyrite, that can be related to specific textural styles. We selected cobalt as a useful trace element, due to its high concentration and wide range in pyrite (270 -22200 ppm). We determined a critical concentration value for cobalt at 3160 ppm, useful as a discriminate between two generations of pyrite. This led to the delineation of a series of dissolution and crystallization events that describe the metamorphic history of the sulfide ore.
As karst systems are natural windows to the underground, speleology, combined with geological sur... more As karst systems are natural windows to the underground, speleology, combined with geological surveys, can be useful tools for helping understand the geological evolution of karst areas. In order to enhance the reconstruction of the structural setting in a gypsum karst area (Vena del Gesso, Romagna Apennines), a detailed analysis has been carried out on hypogeal data. Structural features (faults, fractures, tectonic foliations, bedding) have been mapped in the "Grotta del Re Tiberio" cave, in the nearby gypsum quarry tunnels and open pit benches. Five fracture systems and six fault systems have been identified. The fault systems have been further analyzed through stereographic projections and geometric-kinematic evaluations in order to reconstruct the relative chronology of these structures. This analysis led to the detection of two deformation phases. The results permitted linking of the hypogeal data with the surface data both at a local and regional scale. At the local scale, fracture data collected in the underground have been compared with previous authors' surface data coming from the quarry area. The two data sets show a very good correspondence, as every underground fracture system matches with one of the surface fracture system. Moreover, in the cave, a larger number of fractures belonging to each system could be mapped. At the regional scale, the two deformation phases detected can be integrated in the structural setting of the study area, thereby enhancing the tectonic interpretation of the area (e.g., structures belonging to a new deformation phase, not reported before, have been identified underground). The structural detailed hypogeal survey has, thus, provided very useful data, both by integrating the existing information and revealing new data not detected at the surface. In particular, some small structures (e.g., displacement markers and short fractures) are better preserved in the hypogeal environment than on the surface where the outcropping gypsum is more exposed to dissolution and recrystallization. The hypogeal geological survey, therefore, can be considered a powerful tool for integrating the surface and log data in order to enhance the reconstruction of the deformational history and to get a three-dimensional model of the bedrock in karst areas.
Field studies carried out at Longyearbyen (Spitsbergen, 78º 13' N, 15º 36' E) and at Terra Nova B... more Field studies carried out at Longyearbyen (Spitsbergen, 78º 13' N, 15º 36' E) and at Terra Nova Bay (Antarctica, 74° 41' S, 164° 07' E) question the role of frost action as an efficient rock weathering agent. By carrying out measurements of rock temperature, rock moisture content and Young's modulus variations in both locations, differences between these environments are explained in terms of climate, rock properties and the implications of these properties on the weathering processes involved. The large variability of polar environments, and its repercussions on particular geomorphological processes like rock decay, are highlighted.
Geografiska Annaler: Series A, Physical Geography, 2009
ABSTRACT Ice blisters, typically 0.2–0.8 m high and 5–20 m long, develop annually on perennially ... more ABSTRACT Ice blisters, typically 0.2–0.8 m high and 5–20 m long, develop annually on perennially frozen lakes in Northern Victoria Land. They are believed to be caused by hydrostatic pressures generated through progressive freezing of solute-rich water beneath the lake-ice cover during winter. Lake-ice blisters in the study area differfrom icing blisters described from the northern hemisphere. The latter are caused by hydraulic pressures and are found at locations such as river beds or spring sites on sloping terrain. The Antarctic lake-ice blisters reflect the occurrence of dry-based perennially frozen lakes with high salt contents in an extremely cold and arid environment.
... Earth Surface Processes and Landforms 28: 823836. Hall K, André MF. 2006. ... In ICOM Commit... more ... Earth Surface Processes and Landforms 28: 823836. Hall K, André MF. 2006. ... In ICOM Commit-tee for Conservation, 13th Triennial Meeting, Vol. 2, Vontobel R (ed.). James and James: London; 571577. Mattes U, Turner SJ, Larson DW. 2001. ...
... This figure is available in colour online at www.interscience.wiley.com/journal/espl 13 cm/m ... more ... This figure is available in colour online at www.interscience.wiley.com/journal/espl 13 cm/m or 1·3 m/10 m a significantly rough surface. ... Although seem-ingly 'obvious', once stated, it would appear that the comment regarding this scale attribute by Gómez-Heras et al. ...
Herin mine (Champdepraz, Aosta, Italy), located in Aosta Valley, approximately between 1600 and 1... more Herin mine (Champdepraz, Aosta, Italy), located in Aosta Valley, approximately between 1600 and 1800 m a.s.l., was exploited for at least 250 years for its Cu-Fe sulfide ore. The deposit host rocks belong to the metaophiolitic Zermatt- Saas unit, the eclogitic lower portion of the Piedmont Western Alpine Nappe. The ore mineral association mainly comprises pyrite and chalcopyrite, along with other sulfides such as pyrrhotite, sphalerite, cubanite and oxides (magnetite, rutile, ilmenite). The deposit occurs within lenticular massive bodies and thin layers hosted in various greenschist-facies metamorphosed lithotypes. New data on geometric features, mineralogy, mineral chemistry, petrography, minerography were collected and compared with the existing models for massive-sulfide mineral deposits. We suggest a hydrothermal-volcanogenic primary origin of the mineralization with original characteristics largely obliterated by subsequent metamorphic history. On the basis of studies and our results, we identified two parameters as driving criteria for a comprehension of the multistage process that led to the present configuration of the ore: (a) textural characters of pyrite and (b) distribution of selected trace elements (Co, Ni, As) in sulfides. Spot analyses and atomic maps obtained by electron microprobe provided an integration of these two sets of data. Trace elements, in fact, show a zoned distribution, in particular in pyrite, that can be related to specific textural styles. We selected cobalt as a useful trace element, due to its high concentration and wide range in pyrite (270 -22200 ppm). We determined a critical concentration value for cobalt at 3160 ppm, useful as a discriminate between two generations of pyrite. This led to the delineation of a series of dissolution and crystallization events that describe the metamorphic history of the sulfide ore.
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Papers by Andrea Strini
of the Piedmont Western Alpine Nappe. The ore mineral association mainly comprises pyrite and chalcopyrite, along with other sulfides such as pyrrhotite, sphalerite, cubanite and oxides (magnetite, rutile, ilmenite). The deposit occurs within lenticular massive bodies and thin
layers hosted in various greenschist-facies metamorphosed lithotypes. New data on geometric features, mineralogy, mineral chemistry, petrography, minerography were collected and compared with the existing models for massive-sulfide mineral deposits. We suggest a hydrothermal-volcanogenic primary origin of the mineralization with original characteristics
largely obliterated by subsequent metamorphic history. On the basis of studies and our results, we identified two parameters as driving criteria for a comprehension of the multistage process that led to the present configuration of the ore: (a) textural characters of pyrite and (b) distribution of selected trace elements (Co, Ni, As) in sulfides. Spot analyses and atomic maps obtained by electron microprobe provided an integration of these two sets of data. Trace elements, in fact, show a zoned distribution, in particular in pyrite, that can be related to specific textural styles. We selected cobalt as a useful trace element, due to its high concentration and wide range in pyrite (270 -22200 ppm). We determined a critical concentration value for cobalt at 3160 ppm, useful as a discriminate between two generations of pyrite. This led to the delineation of a series of dissolution and crystallization events that describe the metamorphic history of the sulfide ore.
of the Piedmont Western Alpine Nappe. The ore mineral association mainly comprises pyrite and chalcopyrite, along with other sulfides such as pyrrhotite, sphalerite, cubanite and oxides (magnetite, rutile, ilmenite). The deposit occurs within lenticular massive bodies and thin
layers hosted in various greenschist-facies metamorphosed lithotypes. New data on geometric features, mineralogy, mineral chemistry, petrography, minerography were collected and compared with the existing models for massive-sulfide mineral deposits. We suggest a hydrothermal-volcanogenic primary origin of the mineralization with original characteristics
largely obliterated by subsequent metamorphic history. On the basis of studies and our results, we identified two parameters as driving criteria for a comprehension of the multistage process that led to the present configuration of the ore: (a) textural characters of pyrite and (b) distribution of selected trace elements (Co, Ni, As) in sulfides. Spot analyses and atomic maps obtained by electron microprobe provided an integration of these two sets of data. Trace elements, in fact, show a zoned distribution, in particular in pyrite, that can be related to specific textural styles. We selected cobalt as a useful trace element, due to its high concentration and wide range in pyrite (270 -22200 ppm). We determined a critical concentration value for cobalt at 3160 ppm, useful as a discriminate between two generations of pyrite. This led to the delineation of a series of dissolution and crystallization events that describe the metamorphic history of the sulfide ore.