Smoganica – a Cave Developed in Upper Cretaceous Breccia

Na planoti Banjšice (SZ Slovenija) je najdaljša izvirna jama Smoganica, dolga 492 m. Jama (na nadmorski višini 505 m) leži na jugozahodnem pobočju Čukle (770 m) vzhodno od reke Soče (153 m nad morjem). Smoganica se je razvila v apnenčevi breči, ki je tu debela 10 m in je del zgornjekrednih flišnih plasti. V okolici jame so zeleni laporji kot vključki v breči ali pa je breča vključena v plasti zelenega laporja. Klasti v debelozrnati breči, v kateri je tudi jama, merijo od nekaj cm do več dm v premeru. Klasti večinoma izvirajo iz mlajših rudistnih apnencev, spodnje in zgornje krede ter jurskih mikritnih in oolitnih apnencev. Jama Smoganica leži okrog 2 km južno od Idrijskega preloma in okrog 200 m severno od Kobariškega preloma. V jami zasledimo dve glavni razpoklinski smeri: N30-45°E in N120-135°E. Smoganica se je oblikovala kot sistem manjših rovov, ki so se razvili znotraj breče v vseh smereh. Jama je nastala v freatičnih razmerah. Kasneje je bila v celoti zapolnjena s sedimenti, nad katerimi so nastale nadsedimentne skalne oblike. Sedimenti so bili nato iz jame odnešeni. Današnji vodni tok oblikuje dno jamskih rovov. Višje vode oblikujejo fasete in draslje, nižje pa talne žlebove. Jamo lahko opredelimo kot poligenetsko, saj je njene dele že povsem preoblikovala voda, ki prenika s površja in polzi po jamskih stenah. On the Banjšice plateau (NW Slovenia) the longest spring cave is 492 m long Smoganica. The cave (505 m above sea level) is situated on the SW slope of Čukla (770 m) E from the Soča river (153 m above the sea level). Smoganica is developed in limestone breccia, which is 10 m thick and belongs to the Upper Cretaceous flyschrocks. On the territory around the cave, the green marls are included in breccias or breccias are included into the green marls. Clasts in coarse-grained breccia, in which the cave is located, vary from some cm to several dm in diameter. Clasts are mostly deriving from younger rudist limestones, Lower and Upper Cretaceous and Jurassic micritic and oolitic limestones. Smoganica is situated about 2 km south from Idrija fault and about 200 m north from Kobarid fault. There are two principal fissure orientations in the cave, N30-45ºE and N120-135ºE. Smoganica was formed from the system of smaller passages that have been developed inside the breccia in 3D. The cave was formed in phreatic conditions, later it was completely filled with cave sediments.In the next stagethe above-sediment rock forms were developed. Cave sediments were later removed from the cave. Today the active water stream is cutting rock forms in the bottom of the cave passages. Higher water quantities are forming scallops and potholes and lower quantities floorchannels. Smoganica can be described as polygenetic cave because the percolating water is reshaping the passages.

Biostratigraphy and lithostratigraphy of the Mid-Carboniferous boundary beds in the Muradymovo section (South Urals, Russia)

The uninterrupted succession of the Mississippian–Pennsylvanian boundary beds in the Muradymovo section in the South Urals contains diverse fossils and has a high correlative potential. The Muradymovo section is located in the Zilair Megasynclinorium (ZM), which belongs to the West Uralian Subregion and displays carbonate-siliciclastic deep-water facies of the Bukharcha Formation, which is partly Serpukhovian (Kosogorian, Protvian and Yuldybaevian) and partly Bashkirian (Syuranian). In the southern ZM, the lower part of the formation contains argillaceous carbonates with beds of shale and siltstone, subordinate clastic limestones and limestone breccia, while the upper part is mostly limestone with cherty interbeds. In the north of the ZM, the formation mainly consists of limestone. The Muradymovo succession contains no identifiable gaps in the Mid-Carboniferous Boundary (MCB) portion and has a succession of foraminiferal, conodont, ammonoid and ostracod zones. The MCB in this section coincides with the base of the Bogdanovkian and is defined by the entry ofDeclinognathodus noduliferus.This level falls within the upper part of the foraminiferalMonotaxinoides transitoriusZone, is near the base of the ammonoidHomoceras–HudsonocerasGenozone and can be correlated worldwide.

Slide origin of breccia lenses in the Cambrian of the North China Platform: new insight into mass transport in an epeiric sea

An oolite in the Furongian (Late Cambrian) Chaomidian Formation in Shandong Province, China, which was deposited on the North China Platform in an epeiric sea, contains several limestone breccia lenses of various dimensions (centimetres to decimetres thick and decimetres to more than 10 metres in length) in an E-trending section. The oolite, which is approximately 40 cm thick, was originally thicker, as indicated by a planar truncation surface that formed by wave abrasion. The breccia lenses in this oolite are generally mound-shaped with a flat base and a convex top. The western margin of the lenses is commonly rounded whereas the eastern margin commonly has a tail (consisting of a rapidly eastwards thinning breccia horizon that gradually ends in a horizon of isolated clasts). Some of the breccia lenses are underlain by a shear zone. The formation of the breccia lenses cannot be easily explained by normal depositional or deformational processes. It is concluded that the lenses represent fragments of a partly consolidated layer, consisting of both rounded and angular platy clasts, which slid down over a very gently inclined sedimentary surface which acted – possibly together with a water film – as a lubricant layer. During transport, the layer broke up into several discrete bodies that formed small ‘highs’ at the sedimentary surface of the shallow epeiric sea. Subsequently, waves partially eroded the lenses, mostly at their margins, producing their mound-shaped form. Sliding of blocks is known from a wide variety of environments in the sedimentary record; however, this is the first description of the sliding of blocks in an epeiric sea. This indicates that such a low-relief submarine carbonate setting is, like its siliciclastic counterparts, susceptible to this process.

Lower Ordovician (Arenig–Llanvirn) graptolites from the Notre Dame Subzone, central Newfoundland

Many lower Paleozoic rocks in the Notre Dame Subzone of central Newfoundland are of unknown or imprecise age. Several new Lower Ordovician graptolite occurrences are here reported and earlier records revised. New graptolite localities in the Balsam Bud Cove Formation at Snooks Arm on the Baie Verte Peninsula, previously recorded as "early Ordovician (Arenig)" have yielded an assemblage identical to that found in the middle part of Bed 11 of the Cow Head Group, western Newfoundland, indicating a probable lower Didymograptus bifidus Zone age. At Corner Pond, southeast of Corner Brook, an abundant, diverse fauna from the Corner Pond formation indicates a marginally older age for the black shales than those at Snooks Arm (Pendeograptus fruticosus Zone, equivalent to lower Bed 11). Black shales associated with felsic volcanics and limestone breccia belonging to the Cutwell Group at Lushes Bight, on Long Island, western Notre Dame Bay, which were previously assigned to the widespread black shales of the Lawrence Harbour Formation and equivalents in the Exploits Subzone, contain a rich lower Llanvirn (Paraglossograptus tentaculatus Zone) graptolite assemblage. This agrees with ages established using other macrofossils and conodonts from the associated limestones. In contrast, a lower shale unit from older strata at Southern Head on the eastern end of the island yields a late Arenig Isograptus victoriae maximus Zone assemblage. These newly discovered graptolite faunas provide precise ages for the upper and lower parts of the volcano-sedimentary sequence on Long Island. Interestingly, all four graptolite assemblages discussed here are of open-ocean affinity, permitting accurate correlation with localities not only in western Newfoundland but also elsewhere in the world.

The first well-preserved radiolarians from the Ordovician of Australia

Late Ordovician radiolarians are described from allochthonous limestone breccia deposits of the graptolitic Malongulli Formation of central New South Wales. Included among the forms are the new ‘palaeoactinommid’ genus Kalimnasphaera with new species K. maculosa, the new entactiniid species, Entactinia subulata, and the new anakrusid species, Auliela taplowensis. A number of other entactiniids and the first recorded Ordovician ‘rotasphaerids’ are placed in open nomenclature. Graptolite faunas of the Malongulli Formation indicate that the deposits range in age from the Eastonian Zone of Dicranograptus hians kirki to the Bolindian Zone of Climacograptus uncinatus, that is, from latest Caradoc to early or middle Ashgill in age. This is only the second known well-preserved radiolarian assemblage to be illustrated from Late Ordovician (late Caradoc–Ashgill) successions, and the earliest known from Australia. The radiolarians typically occur in tabularly shaped, laminated lime-mudstone clasts with an abundance of siliceous sponge remains. These clasts appear to be formed from peri-platform ooze of the ‘deeper-water’ slope facies, which became incorporated in debris flows moving into the adjoining basin.