Fosilni vretenčarji in paleomagnetna posodobitev ene od zgodnjih faz razvoja jam na Klasičnem krasu, Slovenija: pliocen Črnotič II in Račiške pečine Na Klasičnem krasu so paleontološki podatki prvič omogočili uskladitev magnetostratigrafski� podatkov z geomagnetno polarizacijsko časovno skalo. Na dve� proučeni� mesti�: (i) v profilu s sigami in rdečimi ilovicami v Račiški pečini (Matarsko podolje) in (ii) v brezstropi jami, lokacija Črnotiče II (Podgorski kras), ki je zapolnjena s fluvialnimi klastičnimi sedimenti prekritimi s sigo. Ta zadnja lokacija se odlikuje z bogatim na�ajališčem fosilni� cevčic jamskega serpulida marifugia cavatica. Ostanke vretenčarjev predstavljajo predvsem fragmenti sklenine glodalcev in soricomorfov. Odsotnost volu�aric brez zobni� korenin, kakor tudi taksonomska sestava sesalske favne, kažeta na pliocensko starost obe� lokacij. Favna iz (i) Račiške pečine (z Apodemus, cf. Borsodia) pripada srednji do pozni bioconi MN17 (ca.1.8-2.4 Ma). Fosilna združba (ii) iz Črnotič II (z Deinsdorfia sp., Beremedia fissidens, Apodemus cf. atavus, Rhagapodemus cf. frequens, Glirulus sp., Cseria sp.) je očitno precej starejša in pripada bioconi MN15¬-MN16 (ca 3.0-4.1 Ma). Z upoštevanjem skladnosti biostratigrafski� in paleomag-netni� datacijski� podatkov in verodostojnega sedimentacijskega okvirja vzorcev predlagamo, da se tako dobljeno datacijo uporabi tudi kot čas, ko se je končala ena od stari� speleogenet-ski� faz na Klasičnem krasu.

UDC 911.2:551.435.8:523.43 Davide Baioni, Nadja Zupan Hajna & Forese Carlo Wezel: Karst landforms in a Martian Evaporitic Dome e Tithonium Chasma is the northern trench of the western troughs of Valles Marineris (Mars). In the eastern part of the canyon system a mountain displaying a dome shape morphology is located. According to OMEGA mineralogical data (OMEGA data orbit 531_3) and further studies the dome appears to consist of magnesium sulphate (kieserite), an evaporitic mineral also found on the Earth. Previous works highlighted the presence of karst-like landforms and morphologies that strongly resemble the evaporitic karst morphologies found on the Earth. rough the analysis of the new MRO HiRISE images we have investigated the Martian landform and the possible processes involved in their formation and shaping in great detail. e analysis carried out show that the landforms observed clearly indicate the presence of solutional processes that also acted in a selective way, highlighting that the Martian dome can be formed of di erent materials (minerals, grain-size, ect.) with di erent solutional properties. e results of our observation also suggest that on the dome liquid water must have existed in the past for enough time so that the solution features we investigated could be formed. Keywords: Mars, kieserite, dissolution, karst features. (Mars). V njegovem vzhodnem delu leži gora, ki kaže značilno kupolasto obliko dome. Mineraloški podatki pridobljeni z OMEGA spektrometrom (podatki OMEGA orbit 531_3) in nadaljnje študije kažejo, da doma sestoji iz magnezijevega sulfata (kizerit), evaporitnega minerala, ki ga najdemo tudi na Zemlji. Predhodne raziskave dome poudarjajo prisotnost krasu podobnih oblik in oblik, močno podobnim oblikam evaporitnega krasa na Zemlji. Z analizami novih posnetkov MRO HiRISE smo raziskovali izbrano Marsovo površino in predvideli možne procese, ki bi lahko imeli pomembno vlogo pri njenem nastanku in oblikovanju. Opravljene analize so potrdile, da opazovane oblike površja jasno nakazujejo prisotnost procesov raztapljanja. Iz oblik se da sklepati tudi na prisotnost selektivne korozije, ki pa tudi nakazuje, da doma sestoji iz različnih materialov (minerali, zrnavost, itd.), ki se drugače obnašajo pri raztapljanju. Rezultati naših opazovanj tudi nakazujejo, da je na domi nekoč morala obstajati tekoča voda in to dovolj časa, da so korozijske oblike lahko nastale. Izvleček

We have conducted palaeomagnetic and magnetostratigraphic research on karst sediments in Slovenia since 1997. More than 2,000 samples were taken and analysed in 36 different profiles at 21 locations in caves and on the surface. Standard palaeomagnetic analyses were used (thermal and alternating field demagnetisation, magnetic susceptibility measurements, etc.). There is no evidence of younger marine deposition than Eocene in the SW part of Slovenia. Younger sediments occur only in caves and very rarely on the karst surface (different soils and a few remains of terrigeneous sediments). Marine and terrestrial Tertiary to Plio-Quaternary deposition occurs in the SE and E Slovenia. Chronostratigraphy of cave sediments in SW Slovenia completed by Rado Gospodarič in the 1980s was based on Pleistocene warm/cold cycles. Later Th/U dating indicated that speleothems from different caves in Slovenia are older. New dating principally results from palaeomagnetism and magnetostratigraphy of cave sediments calibrated, in some sites, by Th/U, palaentological and geomorphological analyses. Calibrated data contributed to the reconstruction of speleogenesis, deposition in caves, and indirectly to the evolution of karst surfaces and succession of tectonic movements. The evolution of caves in the Slovenian territory took part within one post-Eocene karstification period. This period continues to the present, and can be subdivided into individual, but not well limited, phases related to Cenozoic palaeogeographical changes. The period contains distinct phases of massive deposition in caves with as yet still preserved sediments dated to about 5.4-4.1 Ma (Miocene-Pliocene), 3.6-1.8 Ma (Pliocene) and Quaternary, following the cessation of Miocene deposition in the Pannonian Basin in the central, E and SE Slovenia and post-Messinian evolution in the SW and W Slovenia.Keywords: Magnetostratigraphy, dating, cave sediments, Dinaric Karst, Alpine Karst, Isolated Karst, karst periods, karst phases Postojna, and the Speleological Association of Slovenia (JZS); these data were used during our work.Principal karst regions belong to the Southern Alps (Julian Alps, etc.) and External Dinarides (part of the Dinaric Mountain). They function as two totally different morphological units, both with different geology and relief evolution. This review of regional geology and geologic evolution is summarized mainly from Buser (1989), Vrabec & Fodor (2006), Placer (1999 and Pirc (2007).The SW part of Slovenia (External Dinarides) is characterised by the lack of both marine and terrestrial deposits younger than Eocene on the surface, except for different soils and a few remains of sediments in karst depressions (i.e. poljes). The last marine deposition took part here during the Eocene, when a thick pile of flysch siliciclastics was deposited. Jurassic to Paleocene limestones were exposed on the surface during the Oligocene to early Miocene within complicated nappe / overthrust structures. The area is dissected by prominent NW-SE-trending fault zones of Dinar...

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The Postojnska jama–Planinska jama cave system and number of smaller adjacent caves are developed in the Postojnski kras. These caves are located between two dextral strike-slip fault zones oriented in the Dinaric direction. The caves contain lith­ologically diversified cave fill, ranging from speleothems to allo­genic fluvial sediments. The allogenic clastic material is derived from a single source, Eocene siliciclastics of the Pivka Basin. Small differences in mineral/petrologic composition between the sediments can be attributed to different degrees of weather­ing in the catchment area and homogenization of source sedi­ments. Thick sequences of fine-grained laminated sediments, deposited from suspension are common. The depositional en­vironment was mostly calm, but not completely stagnant. Sucha sedimentary environment can be described as cave lacustrine, withdeposition from pulsed flow. The homogeneity of the pa­laeomagnetic data suggests rapid deposition by a number of short-lived single-flood events over a few thousand years. This depositional style was favourable for recording of short-lived excursions in the palaeomagnetic field. The sediments were originally not expected to be older than Middle Quaternary in age (i.e. about 0.4 Ma). Later numerical dating (Th/U and ESR) indicated ages older than 0.53 ka. New palaeomagnetic data from selected sedimentary profiles within the cave system detected normal polarization in muchof the profiles studied. Reverse polarized magnetozones, interpreted mostly as short-lived excursions of magnetic field, were detected in only a few places. Therefore, we interpreted most of the sediments as be­ing younger than 0.78 Ma, belonging to different depositional phases within the Brunhes chron. Palaeomagnetic properties of two profiles in caves intersected by the artificial tunnel be­tween Postojnska jama and Črna jama had reverse polarized magnetozones and of sediments in Zguba jama, may indicate an age muchgreater than 0.78 Ma. The cave system has evolved over a long period of time, governed by the functioning of Pla­ninsko polje in the relation to the evolution of the resurgence area in Ljubljana Moor further to the east. General stabilization of the hydrological system withlow hydraulic head led to the evolution of caves in epiphreatic and paragenetic conditions over a long time-span. Individual cave segments or passages were completely filled and exhumed several times during the evolution of the cave. Alternation of depositional and erosional phases may be connected withchanging conditions within the cave system, the functioning of the resurgence area, collapse, climatic change, tectonic movement and the intrinsic mecha­nisms of contact karst.