Geostructural mapping of karstifid limestones

The goal of the present paper is presentation of the structural mapping of the karstifid limestones, and the relations between the surface and the underground karstifiation. When mapping on the large scale the frequency of the dip and strike must be increased. Possible intebeds of alien rock must be registered. Measurements of the dip make it possible to ascertain possible plicative deformations. Intercalations of non-carbonate rocks inflence the underground water flw and affect the formation, shaping and location of the karst voids as well as the surface karst features. For the understanding of the karstifiation processes exhaustive collection of structural data, and recognition of broken, crushed and fractured zones within and parallel to fault zones, plus thrust– shear–zones are essential. As spatial organization and dimensions of the underground karst voids, as the surface karst shaping are guided by thrust parallel and fault induced deflction structures. All structural elements, which include tectonic elements as well as bedding planes, lithological changes, lithological partings, less permeable or impermeable interbeds, plus structural elements contribute to the structural framework. It directs both vertical percolation and horizontal streaming within the limestone and inflence the frequency, size, spatial distribution, and shape of interconnected karst voids. The later form the speleogenetic network. Due to the permanent denudation the intersection of the Earth surface and the structural framework and speleogenetic network permanently moves downwards. New structural elements emerge while speleological structures change to less recognizable succession objects. The surface of the karst may be characterized as a dynamic, spatial, hydrogeological and speleological succession system permanently affected by the current tectonic activity

Strukturna lega Habečkovega brezna (Idrijsko, Slovenija)

 With detailed geological mapping at a scale 1:5 000, beside general geological data also the structural and tectonical circumstances of the surrounding of Habečkovo brezno were recognised. The complicated tension deformations developed in compressive condition and the thrust contact are the main reasons for development of hydrological and surface karst features. With kinematical reconstruction we recognised that 400 m deep Habečkovo brezno has a special structural and hydrological location.   S podrobnim geološkim kartiranjem smo poleg splošnih geoloških podatkov rekonstruirali tudi strukturne in tektonske razmere. Pri tem smo ugotovili zapletene natezne deformacije, ki jih sicer na prvi pogled ni mogoče razložiti v splošnih tlačnih pogojih. Prav natezne deformacije predstavljajo poleg narivnega kontakta bistveno osnovo za razvoj hidroloških razmer in površinske kraške morfologije obravnavanega terena. Z rekonstrukcijo kinematskega razvoja ozemlja smo ugotovili, da ima 400 m globoko Habečkovo brezno izjemen strukturni in hidrološki položaj.

Structural setting at the contact of the Southern Alps and Dinarides in western Cerkljansko region (western Slovenia)

The area between the villages of Reka in the Idrijca Valley, Bukovo and Zakriž near Cerkno belongs geographically and geotectonically to the Dinarides. The area consists of two large inner thrust blocks of the Trnovo nappe, which were thrusted for tens of kilometers in the direction of SW to their present position. They are overlain by the Tolmin nappe, the lowest thrust unit of the Southern Alps. The Tolmin nappe was thrusted from N to S and consists of two inner thrust blocks and a smaller intermediate inner sheet. In the western part of the area the contact between Southern Alps and the Dinarides runs along the regional Sovodenj fault.Although the rocks in the considered thrust units are about the same age, different stratigraphic settings could be recognized. The lithostratigraphic features of the Ladinian-Lower Carnian Pseudizilian beds are particularly striking. Succession of clastic and carbonate rocks was deposited in deep-marine Slovenian basin. In both the Trnovo and Tolmin nappe, Pseudozilian beds occur in the lithologically characteristic sequences but, in the Tolmin nappe, they are developed in a much greater thickness than in the Trnovo nappe and pass continuously upwards into Amphyclina beds, while in the Trnovo nappe, on the other hand, the succession of Pseudozilian beds is much thinner and is overlain by the platform Cordevol dolomite

Ladinian skonca beds of the Idrija Ore Deposit (W Slovenia)

The richly mineralised Skonca beds (der Lagerschiefer) were the most important mining level of the Idrija ore deposit. In addition to epigenetic ores, exceptional quantities of various rich syngenetic cinnabar ores could be found in these layers. »Jeklenka« (steel ore), »opekovka« (brick ore), »jetrenka« (liver ore), coral ore, and some other bedded cinnabar ores contained up to as much as 78 % Hg. These ores were excavated more or less intensively from their discovery in 1508 until the cessation of works in the Idrija Mine in 1977. The Skonca beds can be found in all parts of the Idrija ore deposit in the form of large or small, irregular, lenseshaped bodies or layers. In the section of the ore deposit known as šTalnina’, the Skonca beds are on average only 4 m thick, and from 10 to maximally 25 m in other parts of the ore deposit. The greatest thickness of these beds, i.e. around 40 m, can be found in the area of the Karóli tectonic unit, situated in the deepest part of the former Idrija Middle Triassic tectonic fault trough. The rocks in the Skonca beds are grouped in typical sequences, which represent a key for the reconstruction of sedimentary environments. The sequences are designated with the letters A, B, C and D. Sequence C is further divided into subsequences C1 with a carbonate and C2 with a siliceous structure. The lithological units of sequence A usually represent the lowest part of the Skonca beds, and may be the lateral equivalents of rocks of series B and subsequence C1. Sequence A is comprised of dispersed, gravelly varieties of carbonatic lythic sandstone, limestone and dolomite siltstone, as well as intercalations of gravelly silty micritic limestone and micritic limestone. Sequence B consists of typical transitional rocks between sequences A and C1, among which silty limestone with transitions to calcitic marlstone and claystone can be found. Sequence C is formed of šclassic’ Skonca rock beds. Although the bottom part of sequence C has a carbonate structure (subsequence C1) and the top part has a siliceous structure (subsequence C2), the rocks cannot be distinguished from one another by their appearance. All are strongly bituminous and shaly. Sequence C is comprised of grey to black bituminous dolomite and quartz sandstone rich in pyrite and marcasite, dolomite or quartz siltstone, and shaly claystone with coal inclusions. The sequence of C rocks ends with clayey-lythic quartz sandstone containing remains of the brachiopod Discina. These are followed by various pyroclastic rocks of sequence D. The Skonca beds and the rich bedded cinnabar ores have various sedimentary structures which accurately define the events and environments of their origin. Except for the erosion channels, which are filled with dolomite gravel, there are no other presedimentary structures in the Skonca beds (subsequence C1). However, the beds are rich in synsedimentary physical forms, particularly various stratifications, laminations and various forms of graded bedding. Among the postsedimentary structures, mention should be made of the abundant sinking and slump structures. In some places, bioturbation and the replacement of organic particles with pyrite can be observed. The Skonca beds were deposited in a spatially complex, marsh-lacustrine-lagoonal environment. The rocks of sequence A and partly also of sequence B were formed in an alkaline, oxygen-rich environment, and the lithological units of subsequence C1 in a reductive environment. The rapid transitions among rocks indicate strictly limited and slow lateral inflows of fresh water into the marshy environment overgrown with low vegetation. The rocks in subsequence C2 prove that the freshwater marsh was flooded with sea water. Deposited in the shallow, closed lagoon overgrown with low vegetation were various bituminous shales, mudstones and sandstones filled with numerous radiolarians and needles of siliceous sponges and coal intercalations. The sedimentation of the Skonca beds ends with quartz sandstone containing deposited remains of the brachiopod Discina. The Skonca beds cover a layer of various pyroclastic rocks that is up to 80 m thick

NARAVOSLOVNI OPIS IDRIJSKEGA RUDNIKA V HACQUETOVEM DELU »ORYCTOGRAPHIA CARNIOLICA« (1781)

In the second volume of the "Oryctographia Carniolica" (1781), Hacquet published an extensive and detailed report on the Idrija mine. This paper underlines some interesting sides of his naturalistic (geological) description of the ore deposit.V drugi knjigi svoje "Oryctographia Carniolica" (1781) je Hacquet objavil obsežno vsestransko poročilo o idrijskem rudniku. V prispevku opozarjamo na nekatere posebnosti in zanimivosti njegovega naravoslovnega (geološkega) opisa rudišča in ozemlja nad njim

HACQUETOVA OCENA NEKATERIH STAREJŠIH DEL O IDRIJSKEM RUDNIKU

The paper deals with Hacquet's unacceptable criticism of Scopoli's "geological" works on the Idrija mercury ore (1761, 1769) and Ferber's description of the Idrija mine (1774).V zapisu opozarjamo na nesprejemljivo Hacquetovo oceno Scopolijevih "geoloških" del o idrijskem rudišču (1761, 1769) in ferberjevega opisa idrijskega rudnika (1774)

Velika Jeršanova Doline - a Former Collapse Doline

Velika Jeršanova dolina (n.m.v.=535 m) leži na površju nad sistemom Postojnskih jam. Njeno poglabljanje je nedvomno prekinilo nadaljevanje Pisanega rova (n.m.v.=535,5 m) proti S. Čez Veliko Jeršanovo dolino poteka teme Postojnske antiklinale v smeri SZ-JV. Prav tako smer ima tudi Jeršanov prelom. Vpad in smer tankoplastnatih turonijskih in cenomanijskih apnencev sta v temenu antiklinale zelo neurejena. Apnenci vpadajo pod kotom 5-25°. Velika Jeršanova dolina danes nima značilne oblike udornice. Kot najpomembnejši vzrok netipične udorne oblike Velike Jeršanove doline zagovarjamo njen nastanek v temenskem delu Postojnske antiklinale, oblikovanje v tankoplastnatih bolj glinastih apnencih, ki so ob Jeršanovem prelomu precej pretrti ter intenzivno korozijsko zniževanje terena. Glede na današnjo oblikovanost pobočij in zunanjih robov je Velika Jeršanova dolina relikt nekdanje izrazite udornice.The Velika Jeršanova doline (a.s.l.=535 m) is situated on the surface above the Postojnska Jama cave system. Its deepening undoubtedly interrupted the continuation of Pisani rov (a.s.l.=535,5 m) towards N. Through the Velika Jeršanova doline the Postojna anticline crest runs in the direction of NW-SE. The same direction has also the Jeršan fault. Strike and dip of thin bedded Turonian and Cenomanian limestones are disordered on the anticline’s crest. The limestones dip 5-25°. The Velika Jeršanova doline today does not have the typical shape of a collapse doline. The main cause for the untypical collapse shape of Velika Jeršanova doline is its formation in the Postojna anticline crest, its shaping in thin bedded clay - rich limestones and intensive erosional lowering of the area. Regarding the actual shape of the slopes and outer edges, the Velika Jeršanova doline is a relic of a former well shaped collapse doline

Influence of mercury ore roasting sites from 16th and 17th century on the mercury dispersion in surroundings of Idrija

In the first decade of mercury mining in Idrija the ore was roasted in piles. After that the ore was roasted for 150 years, until 1652, in earthen vessels at various sites in the woods around Idrija. Up to present 21 localities of ancient roasting sites were established.From the roasting areas Frbej‘ene trate, lying on a wide dolomitic terrace on the left side of the road from Idrija to ^ekovnik, 3 soil profiles are discussed. In all three profiles in the upper, organic matter rich soil horizon very high mercury contents (from 3 to 4,000mg/kg) were found. In two profiles the contents rapidly decrease with depth, to about 10- times lower values already at 0.5 m. Below that, the mercury contents decrease slowly, to reach at the 1.3 m depth a few mg/kg metal. In the third profile the upper humic layer is followed downward by an additional humic layer containing very abundant pottery fragments. In this layer the maximum mercury contents were determined, 7.474 mg/kg Hg. The underlying loamy soil contains between 1000 and 2000 mg/kg mercury. Pšenk is one of the larger localities of roasting vessels fragments. It is located at Lačna voda brook below Hlev{e, above its confluence with the Padar ravine. The most abundant pottery remains are found in the upper western margin of the area, just below the way to Hleviše. The considered geochemical profile P{enk contains at the top a 45 cm thick humic layer with 4,000 to 5,000 mg/kg mercury. Deeper the contents fall to around 100 mg/kg mercury. The alculations result in an estimated amount of 1.4 t mercury still present at the P{enk locality, and in about 40 t of mercury on all roasting sites described up to present.The determined mercury contents in soils at old roasting sites are very high, and they surpass all hitherto described localities at Idrija and in the surroundings