Paleomagnetic Dating of Sediments in Caves Opened During Highway Construction Near Kozina, Slovenia

V članku poročamo o paleomagnetizmu jamskih sedimentov v JZ Sloveniji. Vzorci so bili vzeti iz dveh denudiranih jam, ki sta se v letu 1999 odprli ob gradnji avtoceste pri Kozini. Vsi vzorci so pokazali normalno magnetno polariteto. Imeli so dobro vzorčno moč in le eno paleomagnetno komponento. Vzorci SLO033- SLO036 kažejo dobro usmerjenost nekoliko bolj zahodno, kot je današnje polje in so mlajši od 0,73 Ma. Vzorci SLO037-SLO042 so usmerjeni nekoliko proti vzhodu glede na sedanje polje in pripadajo zadnjemu normalnemu magnetnemu obdobju ali pa razkrivajo enega od starejših normalnih magnetnih obdobij.We report on the paleomagnetism of cave sediments from SW Slovenia. Samples were taken from 2 denuded caves that were opened during highway construction in 1999 near Kozina. All samples showed normal magnetic polarity, had good sample strength, and had only 1 paleomagnetic component. Samples SLO033-SLO036 showed good directional clustering slightly West of the present day field, and are younger than 0,73 Ma. Samples SLO037-SLO042 clustered slightly East of the present day field, and either reveal paleosecular variation or belong to an older normal magnetic chron

Age and Magnetism of Cave Sediments from Postojnska jama Cave System and Planinska jama Cave, Slovenia

Iz 3-eh različnih lokacij v Postojnskem jamskem sistemu in iz ene lokacije v Planinski jami smo analizirali 28 vzorcev za paleomagnetizem. To so prvi objavljeni rezultati o paleomagnetizmu jamskih sedimentov iz teh dveh jam. Sedimenti kažejo normalni magnetni obrat saj so bili odločeni v Brunhes normalnem obdobju (mlajše od 0,73 Ma). V zgornjem nivoju sistema Postojnskih jam pa sedimenti kažejo magnetni obrat, ki ga uvrščamo med 0,73-0,90 MaWe completed paleomagnetic analyses of 28 samples of cave sediments from 3 different locations in Postojnska jama cave system and one location in Planinska jama cave. These are the first published paleomagnetic studies of cave sediments from these caves. These sediments showed normal polarity, and were deposited during the Brunhes Normal Epoch (younger than 0,73 Ma). However, an additional more complex sediment deposit in an upper section of the Postojnska jama cave system, showed reverse polarity, probably indicating an age between 0,73 and 0,90 Ma

Evidence of a plate-wide tectonic pressure pulse provided by extensometric monitoring in the Balkan Mountains (Bulgaria)

The EU-TecNet monitoring network uses customized three-dimensional extensometers to record transient deformations across individual faults. This paper presents the first results from two newly established monitoring points in the Balkan Mountains in Bulgaria. The data from Saeva Dupka, recorded across an EEN-WWS striking fault, show sinistral strike-slip along the fault and subsidence of the southern block. Much of the subsidence occurred around the time of the distal MW = 5.6 Pernik Earthquake. An important transient deformation event, which began in autumn 2012, was reflected by significant compression and following extension, across the monitored fault. The data from Bacho Kiro, recorded across a NE–SW striking fault, show sinistral strike-slip along the fault and subsidence of the north-western block. The same important deformation event was reflected by changes in the strike-slip, dip-slip, and horizontal opening/closing trends. These results have been compared to data from other monitoring points in the Western Carpathians, External Dinarides, and Tian Shan. Many of the sites show evidence of simultaneous displacement anomalies and this observation is interpreted as a reflection of the plate-wide propagation of a tectonic pressure pulse towards the end of 2012

Catalytic reaction of cytokinin dehydrogenase: preference for quinones as electron acceptors.

The catalytic reaction of cytokinin oxidase/dehydrogenase (EC 1.5.99.12) was studied in detail using the recombinant flavoenzyme from maize. Determination of the redox potential of the covalently linked flavin cofactor revealed a relatively high potential dictating the type of electron acceptor that can be used by the enzyme. Using 2,6-dichlorophenol indophenol, 2,3-dimethoxy-5-methyl-1,4-benzoquinone or 1,4-naphthoquinone as electron acceptor, turnover rates with N6-(2-isopentenyl)adenine of approx. 150 s(-1) could be obtained. This suggests that the natural electron acceptor of the enzyme is quite probably a p-quinone or similar compound. By using the stopped-flow technique, it was found that the enzyme is rapidly reduced by N6-(2-isopentenyl)adenine (k(red)=950 s(-1)). Re-oxidation of the reduced enzyme by molecular oxygen is too slow to be of physiological relevance, confirming its classification as a dehydrogenase. Furthermore, it was established for the first time that the enzyme is capable of degrading aromatic cytokinins, although at low reaction rates. As a result, the enzyme displays a dual catalytic mode for oxidative degradation of cytokinins: a low-rate and low-substrate specificity reaction with oxygen as the electron acceptor, and high activity and strict specificity for isopentenyladenine and analogous cytokinins with some specific electron acceptors