Lithofacies characteristics of the Smrekovec volcaniclastics, northern Slovenia

Abstract

The Smrekovec mountains are characterised by a widespread occurrence of volcanic rocks of the Upper Oligocene age. Their development is closely related to volcanic activity which resulted in the formation of a submarine stratovolcano complex, emplaced onto pre-Tertiary carbonate basement and locally, on Upper Oligocene marine marls and silts. Magma composition varied with time during volcanic activity. The original tholeiitic magmas very likely underwent a differen tiation due to low pressure crystal fractionation, resulting in the development of andesitic and finally rhyodacitic magmas. The early stage of volcanic activity was dominantly non-explosive; the main style of fragmentation was autoclastic, relat ed to chill and quench processes that affected lavas and high-level intrusive bod ies. During the late-stage of volcanic activity, explosive volcanism was also pre sent, being most probably related to magmatic and combined magmatic-hydrovolcanic activity. Explosions also seem to have generated or triggered volcaniclastic debris flows and turbidity ash flows. Shallow intrusive bodies (syn-volcanic sills and feeder dykes) were a local source of heat that generated hydrothermal/geothermal conditions in the enclos ing, water-saturated volcaniclastic sediments. Consequently laumontite, analcime, clinoptilolite, heulandite, thomsonite, yugawaralite, prehnite, pumpellyite, albite, apophyllite, epidote, sphene, chlorite and mixed-layered clay minerals developed as replacements of the primary constituents, interstitial fillings and vein minerals. Kratka vsebina Smrekovško podgorje grade vulkanske kamnine zgornjeoligocenske starosti. Njihov nastanek je vezan na razvoj vulkanskega masiva, sestavljenega iz enega ali več stratovulkanov, ki so delovali v morskem okolju. Podlaga sestoji iz mezozojskih karbonatnih kamnin, ponekod tudi iz zgornjeoligocenskih laporjev in meljevcev. Sestava magme se je med vulkanskim delovanjem spreminjala. Prvotna sesta

Paleoenvironmental evolution of the Paratethys in the Slovenian Basin during the Late Paleogene

“…The increase of terrigenous sedimentation in the upper Tegel and Tuffite units is documented by numerous turbidite layers. This change in sedimentation might reflect both the seismic activity of the Smrekovec volcanism (Kralj 1996) and an uplift of the hinterland. The poor preservation and dominance of agglutinating taxa in the foraminiferal fauna of the Tuffite unit is likely the result of carbonate dissolution and an instable environment associated with the nearby volcanic activity.…”

“…According to biostratigraphic results the Tegel unit was deposited during the Rupelian time and most likely comprises the nannoplankton zones NP22/23 in the lower part to NP24 in the upper part (Hemleben 1964;Jelen et al 1980;Bricl and Pavsic 1991;Scherbacher 1999). The first volcanoclastic sediment layers mark the transition to the approximately 800-to 1000-m-thick Tuffite unit which is dominated by silty marls and tuffites related to the nearby Smrekovec volcanic complex (Kralj 1996). Radiometric dating indicates whole-rock ages of approximately 28 to 22 Ma (Hanfland 1997).…”

Zeolites in volcanic-igneous hydrothermal systems: a case study of Pauzhetka geothermal field (Kamchatka) and Oligocene Smrekovec volcanic complex (Slovenia)

“…Chemical composition of volcanic products evolved in time from basaltic, basaltic andesitic, andesitic, dacitic and finally, to rhyodacitic, forming a volcanic suite (Kralj 1997). Volcanic activity built a complex submarine stratovolcano.…”

“…Emplacements of shallow intrusive bodies into unconsolidated volcaniclastic sediments produced peperites and peperitic breccias. In the late-stage peperites, peperitic breccias and hyaloclastites become significant, and are commonly altered in medium-and low-temperature propylitization conditions (Kralj 1997).…”

Facies architecture of the Upper Oligocene submarine Smrekovec stratovolcano, Northern Slovenia

“…1), reflects to a large extent the interplay of processes originating from volcanic activity and a sedimentary environment (Kralj, 1996). The SVC occurs in an up to 1000 m thick sequence of Tertiary marine clastic sediments deposited in the Smrekovec Basin (Mioč, 1983;Jelen et al, 2008), one of several small and marginal sub-basins in the south-west of the Pannonian back-arc realm (Royden, 1988).…”