20.500.12556/DiRROS-17792 Geološka spremljava poskusnega odkopa uranove rude na Žirovskem vrhu Geological control of trial excavation of Uranium ore in Žirovski vrh Leta 1981–1983 je bilo na Rudniku Žirovski vrh pred pričetkom redne proizvodnje izvedeno poskusno odkopavanje uranove rude za preverjanje metod geološke in radiometrične kontrole ter tehničnih metod pridobivanja. Poskusni odkop je bil v bloku 1, na skrajnem severozahodnem delu rudišča v zgornji gubi dvojne S strukture. V tem bloku se je orudenje nahajalo samo v horizontu sivega peščenjaka debeline 20–30 m. Z geološko spremljavo odkopavanja smo potrdili, da so bili peščenjaki odloženi v sekvencah debelih od par dm do več kot 2 m. Sekvenca je običajno pričenjala z debelozrnatim peščenjakom, večkrat so bili na bazi prisotni še klasti kremena in muljevca. Navzgor je debelozrnat peščenjak pogosto prehajal v srednjezrnatega, redkeje pa še v drobnozrnatega in meljevec. V peščenjakih je bila značilna prisotnost organskih drobcev, ki so v diagenezi ustvarjali redukcijsko okolje v katerem se je iz podtalnice izločal uran. Najpogosteje se je orudenje nahajalo v debelozrnatih peščenjakih, običajno v debelejših sekvencah. Orudenje se je zato pojavljalo v več nivojih debelih navadno pod 1m, kjer se je združevalo je skupna debelina presegla tudi 5 m. Dolžina sklenjenega orudenja v vzdolžni smeri je znašala do 150 m, širina od nekaj metrov do več kot 40 m. V vmesnih prekinitvah orudenja smo opazovali, da so peščenjaki iz temnosive in sive barve prehajali v svetlosive in zelenosive, ki so bili le siromašno orudeni ali jalovi. V vzdolžni smeri se je tak prehod zgodil med prerezi P-35 in P-35a, kjer se je tudi zaključilo odkopavanje. V jami sta bila raziskana še prereza P-36 in P-37, kjer pa se je pojavljal pretežno zelenosiv peščenjak z le redkimi lečami siromašnega orudenja. S površinskimi vrtinami sta bila dlje proti zahodu raziskana tudi še dva prereza oddaljena 1,3 in 2,8 km od jamske zgradbe. V teh vrtinah je bilo ugotovljeno nastopanje sivih in zelenosivih peščenjakov z zelo redkimi sledovi orudenja, ki so se menjavali z bolj drobnozrnatimi različki (muljevci), ostanki organske snovi pa so bili v njih zelo redki. Blok 1 je bil zato mejni blok na SZ strani rudišča, predviden za pridobivanje. In 1981-1983, before the start of full production, trial mining of uranium ore was carried out at the Žirovski vrh mine to test the methods of geological and radiometric control as well as the technical methods of extraction. The trial excavation was done in block 1, in the extreme NW part of the mine in the upper fold of the double S structure. In this block, the ore deposits bodies were found only in the horizon of grey sandstone about 20–30 m thick. Geological monitoring of the excavation confirmed that the sandstones were deposited in sequences from a few dm to more than 2 m thick. The sequence usually graded bed started with coarse-grained sandstone, with pebbles of quartz and mudstone occasionally present at the base. Upwards, coarse-grained sandstone often passed into medium-grained, and more rarely into fine-grained sandstone and siltstone. The sandstones were characterized by the presence of organic fragments, which created an anoxic environment during diagenesis and that in turn enabled uranium to precipitate from the groundwater and concentrate in the host rock. Most often, ore bodies were found in coarse-grained sandstones, usually in several sedimentary sequences. As such, ore bodies appear in several sequences, usually under 1 m thick. In some places ore bodies can join together, exceeding 5 m. The length of the uninterrupted ore body in the longitudinal direction was up to 150 m, the width ranges from a few meters to more than 40 m. In the intermediate areas where the ore body is interrupted, we observed that the sandstones changed from dark grey and grey to light grey and greenish grey. These sandstones were usually barren or contained only small concentrations of uranium. In the longitudinal direction, such a transition took place between cross-sections P-35 and P-35a, where excavation was completed. Cross-sections P-36 and P-37 were also investigated inside the mine, where predominantly greenish-grey sandstone with only rare lenses of poor uranium concentrations appeared. Further to the west, two cross-sections 1.3 and 2.8 km from the mine area were also explored with surface boreholes. Grey and greenish-grey sandstones with very rare remains of organic matter and very rare traces of mineralisation were found in these boreholes, alternating with siltstones. Block 1 is therefore considered the boundary block on the NW side of the mine, intended for extraction. uranova ruda poskusno odkopavanje grödenske klastične kamnine Žirovski vrh uranium ore trial excavation Val Gardena clastic rocks Žirovski vrh true false true Geološki zavod Slovenije Slovenski jezik Angleški jezik Neznano 2024-01-15 09:46:02 2024-01-15 09:46:02 2024-01-16 03:40:57 0000-00-00 00:00:00 2023 0 0 str. 73-85 no. 1 vol. 66 2023 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 2023-08-04 553 0016-7789 10.5474/geologija.2023.002 164651779 1853-Article_Text-12342458-2-10-20230804.pdf 1853-Article_Text-12342458-2-10-20230804.pdf 1 435912EA127D48F75BCC449CEC595EB6 6986ec23aee2f74928767d6aa32686deed90e73f1823ec1da7b3fa5e7c54a6bc 9080c90d-b383-11ee-b0d4-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=24146 Geološki zavod Slovenije Geologija 0 0 0