Aleš Havlín - Academia.edu (original) (raw)

Papers by Aleš Havlín

Lithos, 2011

A peralkaline, ultrapotassic dyke found at Šebkovice (Třebíč district, western Moravia) is a mine... more A peralkaline, ultrapotassic dyke found at Šebkovice (Třebíč district, western Moravia) is a mineralogically extreme member of a dyke swarm occurring along the southeastern border of the Moldanubian Region of the Bohemian Massif. The dyke shows a simple zoning, with a very fine-grained marginal zone grading into a medium-grained central zone. It has a primary mineral assemblage of microcline and potassic amphiboles, with accessory apatite and altered phlogopite. The microcline exhibits an unusual red luminescence colour and pronounced substitution of Fe 3+ for Al, with measured contents of Fe 2 O 3 up to 8.5 wt.% (0.31 apfu Fe 3+). Amphiboles have very high K (up to 0.99 apfu) and Si contents; their compositions follow an alkaline fractionation trend from potassic-richterite to potassic-magnesio-arfvedsonite, characterized by an increase of Na/K and a decrease of Ca, Mg, Fe 2+ and Ti via heterovalent substitutions [B] Ca + [C] (Mg,Fe 2+) → [B] Na + [C] Fe 3+ and Ti +Mg → 2Fe 3+. The most evolved apatite is significantly enriched in SrO (up to 9.7 wt.%; 0.49 apfu Sr). The core of the dyke and late veinlets contain unique late-to post-magmatic Ba-Ti-Zr-bearing mineral assemblages of baotite, henrymeyerite, titanite, rutile, benitoite and bazirite. Anhedral baotite fills interstices distributed inhomogeneously in the dyke centre; it is locally replaced by a Ba-bearing titanite + henrymeyerite + rutile + quartz assemblage. Henrymeyerite (the second record in a lamproite) shows variable Fe/Ti ratios and represents a solid solution of the hepta-and hexatitanate components. Euhedral crystals of benitoite and bazirite are enclosed in the late-stage quartz-titanite-apatite veinlets in the finegrained margin of the intrusion. In terms of a mineralogical-genetic classification, the Šebkovice dyke can be considered as a new high-silica (~57 wt.% SiO 2) variety of lamproite (variety Šebkovice), and represents a unique expression of post-collisional potassic magmatism on the southeastern border of the Bohemian Massif. The peralkaline dykes from this area show mineralogical and geochemical features similar to those of silicarich orogenic lamproites emplaced at destructive plate margins. In terms of the modern classification of lamproites, the Šebkovice dyke is the first lamproite recognised in the Variscan orogenic belt.

The geophysical method of Very Low Frequencies (VLF) was applied to find conductive zones in the ... more The geophysical method of Very Low Frequencies (VLF) was applied to find conductive zones in the depths between 30 and 60 meters in the surrounding of Hranická propast abyss. Such conductive zones occur along the faults or tectonic lines or crevices with sediments especially close to the underground water level. They can represent corrosive caves in the hydrothermal karst that is typical for Hranice karst. In the area of 12 ha in the surrounding of Hranická propast abyss there were found 3 main conductive zones (B 1 , B 2 , B 3) in the direction of approx. 90° (E-W) and one zone (A) in the direction approx. 110-120° which is crossing the abyss. The pilot drilling was unsuccessful, no concrete karst objects were discovered. The sample taken from borehole cores had only redeposited flysh fossils, not show qualification of dating of sediments.

Acta Geologica Slovaca, Jun 15, 2016

The paper presents use of logistic regression and analysis tools implemented in the Geographic In... more The paper presents use of logistic regression and analysis tools implemented in the Geographic Information System (GIS) environment for landslide susceptibility assessment. As a case study, the middle part of the Chriby Mountains (Czech Republic) widely aff ected by landslides was selected, with a total area of 147 km. The landslide susceptibility assessment is based on the comparison and statistical elaboration of territorial dependence on input factors infl uencing the instability of the slopes. In this study, the lithology, slope angle, distance to stream, hypsographic level, and the current land cover were evaluated as the factors infl uencing slope stability and their susceptibility to sliding. The comparison shows that the high susceptibility to sliding is primarily in the areas of potential landslides and active, while 62 % of existing slope failures are created in areas highly susceptible to sliding, 32 % are in areas susceptible to moderate sliding. The remaining 6 % of the...

The European vision outlined, which is only one of many visions possible, is a result of a three ... more The European vision outlined, which is only one of many visions possible, is a result of a three year learning process. The R&Dialogue consortium discussed the experiences made and lessons learned during the ten country dialogues. Based on these findings an overall vision for Europe has been constructed. The vision tries to highlight the insights of this mutual learning process, but clearly it does not necessarily reflect the opinions and interests of all the external stakeholders involved. The chapter ‘Vision for Europe in 2050’ lays out the characteristics of a possible low- carbon Europe in the future. The chapter ‘Ways of getting to the low-carbon society’ gives recommendations for how to achieve this transition.

Application of logistic regression for landslide susceptibility assessment in the middle part of ... more Application of logistic regression for landslide susceptibility assessment in the middle part of Chriby Mts.

Lithos, 2011

A peralkaline, ultrapotassic dyke found at Šebkovice (Třebíč district, western Moravia) is a mine... more A peralkaline, ultrapotassic dyke found at Šebkovice (Třebíč district, western Moravia) is a mineralogically extreme member of a dyke swarm occurring along the southeastern border of the Moldanubian Region of the Bohemian Massif. The dyke shows a simple zoning, with a very fine-grained marginal zone grading into a medium-grained central zone. It has a primary mineral assemblage of microcline and potassic amphiboles, with accessory apatite and altered phlogopite. The microcline exhibits an unusual red luminescence colour and pronounced substitution of Fe 3+ for Al, with measured contents of Fe 2 O 3 up to 8.5 wt.% (0.31 apfu Fe 3+). Amphiboles have very high K (up to 0.99 apfu) and Si contents; their compositions follow an alkaline fractionation trend from potassic-richterite to potassic-magnesio-arfvedsonite, characterized by an increase of Na/K and a decrease of Ca, Mg, Fe 2+ and Ti via heterovalent substitutions [B] Ca + [C] (Mg,Fe 2+) → [B] Na + [C] Fe 3+ and Ti +Mg → 2Fe 3+. The most evolved apatite is significantly enriched in SrO (up to 9.7 wt.%; 0.49 apfu Sr). The core of the dyke and late veinlets contain unique late-to post-magmatic Ba-Ti-Zr-bearing mineral assemblages of baotite, henrymeyerite, titanite, rutile, benitoite and bazirite. Anhedral baotite fills interstices distributed inhomogeneously in the dyke centre; it is locally replaced by a Ba-bearing titanite + henrymeyerite + rutile + quartz assemblage. Henrymeyerite (the second record in a lamproite) shows variable Fe/Ti ratios and represents a solid solution of the hepta-and hexatitanate components. Euhedral crystals of benitoite and bazirite are enclosed in the late-stage quartz-titanite-apatite veinlets in the finegrained margin of the intrusion. In terms of a mineralogical-genetic classification, the Šebkovice dyke can be considered as a new high-silica (~57 wt.% SiO 2) variety of lamproite (variety Šebkovice), and represents a unique expression of post-collisional potassic magmatism on the southeastern border of the Bohemian Massif. The peralkaline dykes from this area show mineralogical and geochemical features similar to those of silicarich orogenic lamproites emplaced at destructive plate margins. In terms of the modern classification of lamproites, the Šebkovice dyke is the first lamproite recognised in the Variscan orogenic belt.

The geophysical method of Very Low Frequencies (VLF) was applied to find conductive zones in the ... more The geophysical method of Very Low Frequencies (VLF) was applied to find conductive zones in the depths between 30 and 60 meters in the surrounding of Hranická propast abyss. Such conductive zones occur along the faults or tectonic lines or crevices with sediments especially close to the underground water level. They can represent corrosive caves in the hydrothermal karst that is typical for Hranice karst. In the area of 12 ha in the surrounding of Hranická propast abyss there were found 3 main conductive zones (B 1 , B 2 , B 3) in the direction of approx. 90° (E-W) and one zone (A) in the direction approx. 110-120° which is crossing the abyss. The pilot drilling was unsuccessful, no concrete karst objects were discovered. The sample taken from borehole cores had only redeposited flysh fossils, not show qualification of dating of sediments.

Acta Geologica Slovaca, Jun 15, 2016

The paper presents use of logistic regression and analysis tools implemented in the Geographic In... more The paper presents use of logistic regression and analysis tools implemented in the Geographic Information System (GIS) environment for landslide susceptibility assessment. As a case study, the middle part of the Chriby Mountains (Czech Republic) widely aff ected by landslides was selected, with a total area of 147 km. The landslide susceptibility assessment is based on the comparison and statistical elaboration of territorial dependence on input factors infl uencing the instability of the slopes. In this study, the lithology, slope angle, distance to stream, hypsographic level, and the current land cover were evaluated as the factors infl uencing slope stability and their susceptibility to sliding. The comparison shows that the high susceptibility to sliding is primarily in the areas of potential landslides and active, while 62 % of existing slope failures are created in areas highly susceptible to sliding, 32 % are in areas susceptible to moderate sliding. The remaining 6 % of the...

The European vision outlined, which is only one of many visions possible, is a result of a three ... more The European vision outlined, which is only one of many visions possible, is a result of a three year learning process. The R&Dialogue consortium discussed the experiences made and lessons learned during the ten country dialogues. Based on these findings an overall vision for Europe has been constructed. The vision tries to highlight the insights of this mutual learning process, but clearly it does not necessarily reflect the opinions and interests of all the external stakeholders involved. The chapter ‘Vision for Europe in 2050’ lays out the characteristics of a possible low- carbon Europe in the future. The chapter ‘Ways of getting to the low-carbon society’ gives recommendations for how to achieve this transition.

Application of logistic regression for landslide susceptibility assessment in the middle part of ... more Application of logistic regression for landslide susceptibility assessment in the middle part of Chriby Mts.