Tufa deposits sheltered by inland notches as indicators of Quaternary denudation rates

Vabljeni na predavanje z naslovom Tufa deposits sheltered by inland notches as indicators of Quaternary denudation rates, ki bo v četrtek, 31 maja 2018 ob 17.00 uri v dvorani Zemljepisnega muzeja GIAM ZRC SAZU, Gosposka 16, Ljubljana.

Predavala bo dr. Nurit Shtober-Zisu z Univerze v Haifi, Izrael.

Predavanje bo v angleškem jeziku (povzetek):
Inland notches are elongated concave-shape indentations that develop on the carbonate rocky cliffs of mountainous zones, down to the desert fringe. These unique features formed as a result of the interaction between specific lithological and climatic controls, emphasizing the importance of environment upon rock decay. The vast majority (71%) of inland notches in Israel are formed in hard, dense, and crystalline limestone deposited throughout the Turonian age. Another 27% are cut into the dolomitic sequence of the upper Albian and lower Cenomanian. The rest (2%) are dispersed in the various formations of the Cenomanian and Eocene eras. Inland notches form because of slight differences (1%–15%) in the porosity of the visor and cavity bed: the cavity bed is more porous, so more likely to erode by exfoliation and dissolution. Thus, the cavity bed retreats at a faster rate compared to the slower subaerial dissolution of the visor bed, until a critical point is reached where the visor collapses. In Israel, inland notches inhabit the same lithostratigraphic units as do large caves.

Notches are most common in semi-arid and in Mediterranean climates but mainly in areas with annual rainfall of between 400 mm and 850 mm. In more humid areas (> 900 mm/y) notches are negligible or completely absent, due to the rapid rate of chemical dissolution of carbonate rocks. In the desert fringe (200–300 mm/y), mechanical decay is accelerated and notches exhibit disintegration processes, visor collapse, and rock falls. In the desert area (< 200 mm/y), salt decay replaces the chemical decay, encouraging tafoni formation. In the Mediterranean zone, tufa stalactites and stalagmites occasionally grow within the cavity of the notch. In extremely rare cases they merge into columns, detached from the back wall. The tufa fill, both along the back wall of the notch and in detached stalagmites, is more typical of notches located on north-aspect slopes, which are characterized by a more hydric environment – that is colder, more humid and with a more stable microclimate. The Carmel tufa deposits that grew under the notches visors and on the cavity back-wall were dated by U-Th chronology at the Geological Survey of Israel using ion exchange column chemistry and MC-ICP-MS techniques. The ages were corrected for initial 230Th by using crustal average 232Th/238U atomic ratio of 4.2. In each notch the oldest tufa layer was dated giving the minimum age of the surface formation. Six layers from four tufa samples were dated giving ages spanning from 13,636 ± 834 ky to 37,562 ± 2,397 ky, implying that these notches were formed during the last glacial period, or during the last deglaciation.

Predavanje organizira Geomorfološko društvo Slovenije v sodelovanju z Geografskim inštitutom Antona Melika ZRC SAZU. 

Monitoring of alpine natural hazards by means of UAV´s

V sodelovanju z Geografskim inštitutom Antona Melika ZRC SAZU in Komisijo za uporabo geografskih informacijskih sistemov pri varovanju okolja ZGS (SCGIS Slovenia) smo 22. decembra 2017 organizirali predavanje z naslovom Monitoring of alpine natural hazards by means of UAV´s – case studies from Austria. Avtorji predavanja so bili Wolfgang Sulzer, Gernot Seier (Institute for Geography and Regional Sciences, University Of Graz, Graz, Austria) in Viktor Kaufmann (Institute for Geodesy, Graz University of Technologies, Graz, Austria). Predaval je Wolfgang Sulzer.

Povzetek predavanja (v angleškem jeziku):
UAVs are unmanned and largely autonomously operating aircrafts, which can usually be equipped with imaging systems (video, camera) or other sensors. In recent years, they have increasingly been used for geoscientific issues. Within the framework of the NAWI GRAZ (Natural Sciences Graz) cooperation the Institute for Geography and Regional Sciences (University of Graz) and the Institute for Geodesy (Graz University of Technology) investigate the question of how UAVs can be used to map and quantify changes in the earth’s surface as a meaningful supplement or alternative to conventional research methods. Especially in hard-to-reach alpine areas or in areas that are at risk due to ongoing active processes, such systems offer the possibility of providing high-quality geodata without putting people at risk. 

In this presentation, the authors document the use of UAVs in the field of recognizing and detection of alpine natural hazards on the basis of current projects. For example, following the floods in 2011 and 2017 in the area around the town Oberwölz (Upper Styria), the collection and quantification of increasing fluvial morphological processes (especially sediment load) are in the focus of interest. In the limestone alpine area, the technically similar study for the determination of sediment dynamics in a channel with episodic water flow and high morphodynamics (Langgriesgraben, National Park Gesäuse) is presented. At the Lärchberg / Galgenwald near Murau (Upper Styria) UAV aerial surveys are used to observe and analyze an active landslide area. Finally, the glacier dynamics, in particular the ice breakup at the glacier tongue of the “touristic” Pasterze glacier (National Park Hohe Tauern) will be presented.

In all studies, the challenges of the high alpine environment and the accuracy estimation of the research results are compared with other detection methods, such as ALS or TLS or simply field work. In addition, there are restrictions on accessibility, regulatory (legal) requirements (e.g. UAV law), technical limits or difficult weather conditions (wind, low temperatures, snow, etc.).

PDF datoteka predavanja je dostopna tukaj.

Predavanje je organiziral:
Geografski inštitut Antona Melika ZRC SAZU v sodelovanju z
Geomorfološkim društvom Slovenije ter
Komisijo za uporabo geografskih informacijskih sistemov pri varovanju okolja ZGS.

Zemeljski plazovi – obvladljiv naravni pojav?

Vljudno vas vabimo na predavanje z naslovom Zemeljski plazovi – obvladljiv naravni pojav?, ki bo v torek, 5. decembra 2017 ob 17.00 uri v dvorani Zemljepisnega muzeja GIAM ZRC SAZU, Gosposka 16, Ljubljana.

Predaval bo dr. Jernej Jež z Geološkega zavoda Slovenije. 

Povzetek predavanja:
Zemeljski plazovi so v reliefno razgibanih in geološko pestrih območjih kot je Slovenija lahko resna naravna grožnja infrastrukturi, človeku in njegovemu imetju. Zavedati se moramo, da so tovrstni dogodki v geološki zgodovini nekaj povsem običajnega in jih lahko pričakujemo tudi v prihodnje. Kljub temu so večinoma obvladljiv pojav in nas ne bodo presenečali, če bomo nanje dobro pripravljeni. Med pomembnejše preventivne ukrepe sodijo opozorile karte verjetnosti nastajanja plazov, skalnih podorov in drobirskih tokov. Seveda pa se morajo tovrstne strokovne podlage upoštevati pri umeščanju objektov v prostor, kot tudi že pri predhodnem načrtovanju rabe prostora. Marsikje bi bilo mogoče z minimalnimi stroški posledice pričakovanega plazenja izrazito omejiti ali se jim celo izogniti. Pri raziskavah in napovedovanju pobočnih masnih premikov je mogoče s pridom izkoristiti tudi hitro razvijajoče in lažje dostopne metode daljinskega zaznavanja.

Vabljeni na predavanje o Radovniškem ledeniku

Vljudno vas vabimo na predavanje z naslovom Radovniški ledenik iz obdobja zadnje poledenitve, ki bo v sredo, 10. maja 2017 ob 17.00 uri v dvorani Zemljepisnega muzeja GIAM ZRC SAZU, Gosposka 16, Ljubljana. Predaval bo Luka Serianz z Geološkega zavoda Slovenije.

Povzetek predavanja:
Značilne geološke in geomorfološke oblike v dolini reke Radovne kažejo na pojavljanje poledenitev v različnih obdobjih v pleistocenu. Poleg delovanja ledenika pa je današnja geomorfologija v dolini Radovne posledica tudi aluvialnih procesov. Na izrazit vpliv aluvialnih procesov kažejo številne ledeniško-rečne terase, ki se pojavljajo v celotni dolini, predvsem pa v njenem srednjem in spodnjem delu. Za rekonstrukcijski model, ki temelji predvsem na preteklih opazovanjih hidrogeoloških razmer v dolini, sta bila uporabljena matematično modeliranje in terensko kartiranje. Sledovi zadnje obsežne poledenitve v kateri je deloval Radovniški ledenik so ponekod v dolini še dovolj ohranjeni, da jih je možno uporabiti za validacijo matematičnega modela.

IO GMDS

Vabilo na predavanje dr. Duške Rokavec

Vljudno vas vabimo na predavanje dr. Duške Rokavec z naslovom Gline v litološki sestavi in reliefu slovenskega prostora, ki bo v sredo12. aprila 2017 ob 17.00 uri v dvorani Zemljepisnega muzeja GIAM ZRC SAZU, Gosposka 16, Ljubljana.

Povzetek predavanja:
V raznoliki litološki sestavi slo. ozemlja nastopajo gline v relativno omejenem obsegu in so zato relativno dobro raziskane. Nastopajo v mlajših stratigrafskih enotah, a redkeje v ekonomsko izkoristljivih količinah. Nahajajo se predvsem v ravninskih predelih blizu oz. na površini (z izjemo premoških glin); za njihovo pridobivanje je potrebna začasna degradacija večjih površin, ki pa jih je  sorazmerno enostavno sanirati in jim vrniti prvotni izgled ali dodati novo rabo prostora. Gline bodo predstavljene po naslednjih tematikah:
(1)     pojavljanje/razširjenost in  raziskanost nahajališč glin,
(2)     razdelitev glin glede na njihova izvorna območja ter njihova karakterizacija glede na izvorna območja; skupne ter specifične lastnosti glin in njihova uporabna vrednost, 
(3)     vpliv na prostor in relief zaradi izkoriščanja in sanacije; dodana vrednost glinokopov po končani eksploataciji (avtohtoni ali novi biotopi, mokrišča…).

Lepo vabljeni,
IO GMDS