Przeglqd Geo!ogiczny, vo!. 45, nr 10, 1997
Water geochemistry in the Eastern Carpathians
Angelo Minissale
1,Dimitri Abbado
2,Orlando V aselli2, Zsolt Berner
3,loan Seghedi4, Franco
Tassi2, Stefan Grigoriescu4, Mike loane4, Nara Coradossi2, Mario Paolieri2, Doru Badescu4
&
Alexandru Szakacs4
lCNR-Minerogen. & Applied Geochem., G. La Pira 4, 50121 Florence, Italy
2 Department of Earth Sciences, G. La Pira 4, 50121 Florence, Italy
3Institute of Petrography & Geochemistry, Kaiserstrasse 12, 76187 Karlsruhe, Germany
4Romanian Geological Survey, Caransebes 1, 78344 Bucharest, Romania
The easternmost area of the Carpatho-Pannonian Region (Hargita Mts, Slanic and Vrancea areas) is characterised by a large occurrence of mineralised springs with temperatures. The main purpose of this investigation has been that to determine the hydrogeological pathways and the evolution of the studied waters with special regard to mixing processes at shallow depth. Thus, major, minor and trace components along with oxygen isotopes have been analysed on 72 ther-mal, mineral and stream waters in a NNW -SSE transect from the Transylvanian Basin (Corund) through the volcanic area of Hargita Mts to Slanic and Vrancea areas.
On the basis of the analytical results, the Eastern
Carpat-hians waters can be classified into three groups: 1) Ca-Mg-HC03 waters, mainly related to ground and stream waters circulating in flyschoid formation of the Carpathian chain; 2) Na-CI waters as a result of their circulation in Miocene salt domes occurring in the Corund and Slanic areas; 3) Na-HC03 waters due to the interaction of shallow and/or high salinity waters, with a C0z-rich gas phase which tends to lower the pH values of the interacting waters and modifies their original chemical composition. According to the N a/K, Si02 and KiMg geothermometers, the temperature of the hypothetical reservoirs are always below 150-100°C. On the other hand, the oxygen isotopes prevalently indicate a meteoric origin, their values being between -2.4 and -11.7 per mil (SMOW) for all the studied waters, according to the altitude of the meteoric feeding systems. This may suggest a sort of decoupling with respect to the gas phase, the latter consisting of a significant deep source contribution. In conc-lusion, based on these considerations an evolutive modeling of the mineral and high salinity waters from the Eastern Carpathians is here presented.
Continental collision in the Romanian Carpathians: incorporation of
geophysical data
Victor I. Mocanu
1&
Robert
J.
Lillie2
1 Department of Geophysics, University of Bucharest, 6 Traian Vuia, RO-70139 Bucharest 1, PO 37, Romania
2Department of Geosciences, Oregon State University, 104 Wilkinsion Hall, Corvallis OR 97331-5506, USA
The rise of the Alps and Carpathians and the intermedia-te-crustal depth earthquakes from the Vrancea seismogenic area is a dramatic expression of the on-going orogeny in Central and Eastern Europe. In order to understand the driving mechanisms of this geotectonism, a good know ledge of lithosphere - astenosphere relationship and its dynamics in Cenozoic time is a necessity.
The scenario for the EUROPROBE-P ANCARDI pro-ject is provided by the complex interplay of Alpine and Dinaric collisions and inferred lateral extrusions, Carpathian collision and subduction, and the Pannonian extension. The neotectonics is expressed today only by a snapshot of an orogenic process started in the Mesozoic time. It has invol-ved the Paleogene continental collision of the Eastern Alps and the Balkan orogens, as well as the Neogene subduction further east, resulting in the development of the Carpathian volcanic arc and the back-arc Pannonian basin.
Gravity field of the P ANCARDI region is one of the on-going PANCARDI research, involving colleagues from
1092
University of Bucharest, Oregon State University, Slovak Academy of Sciences, University of Salzburg and Universi-ty of Karlsruhe. As part of this research, a complex study of the gravity field of the Romanian area of the Carpathian arc and surrounding areas was developed in the last year. Mo-reover, some other information is taken into account, as topography, sedimentary thickness, Moho geometry as well as the lithosphere/astenosphere boundary. In addition, the depth distribution ofVrancea earthquakes, both intermedia-te and crustal, seismic reflection and refraction, drillhole information are considered for supplementary constraints.
Previous work has analyzed similar geophysical data to study crustal and litho spheric structure associated to earlier collision in the Eastern Alps and Western Carpathians. High topography, along with thick crust and a broad region of low Bouguer anomalies, suggests about 175 km of continental convergence after the oceanic closure in the Eastern Alps. The Western Carpathians show low topography, thin crust and a narrow region oflow Bouguer anomalies, proving only about 50 km convergence after oceanic closure. The Euro-pean continental passive margin is thought to be beneath the Carpathian mountains.
A network of 12 regional cross sections allows to esti-mate the regional distribution of topography, Moho,
litho-sphere-astenosphere boundary as well as the sediments and associated gravity anomalies. Preliminary modelling on se-lected sections will be presented, showing the misfits of gravity. They will also permit to preliminary analyze the position of the European passive margin beneath the Roma-nian Carpathians.
Przeglqd Geologiczny, vo!. 45, nr 10, 1997
The future plan, as modelling will progress, is mainly dedicated to study the structure of Eastern and Southern Carpathians at the time when the ocean basin has been just closed. The current study may thus be important to appre-ciate the stage of continental collision development in new and ancient mountain belts world-wide.
Apatite-Fission Track dating on sandstones of the Petrosani Basin
Franz Moser
1J Geological Department of the University of Tiibingen,
Sigwartstrasse 10, D-72076 Tiibingen, Germany
The Cretaceous nappe system of the Southern Carpat-hians is dismembered by orogen-parallel wrenching during the Paleogene showing subcrustal deformation. Simultaneous to dextral translation along the Cerna -Jiu strike slip fault system, the
Petrosani Basin subsided on top of a negative flower structure.
Sedimentological investigations show a brackish shallow-water facies during the Oligocene to the Lower Miocene. This environ-ment led to the deposition of coal, followed by sandy to argil-laceous successions. Due to uplift and erosion at the end of the Egerian, subsidence shifted toward the northeastern part of the basin, simultaneously the marine influence retreated towards the Transylvanian basin. This compression in the inner part of the South Carpathians is even documented by subsidence in the foreland depression of the Dacian basin.
During the Middle Miocene, a gap in sedimentation implies a change of subsidence due to tectonic deformation. The structural analysis shows a change of the stress field during the Badenian and Sarmatian within the South Carpathian oro-gen. The right lateral movement along the Cerna Ciu fault-sy-stem is cut off during the Middle Miocene by the dextral Baia de Arama fault. Along the northern rim of the Petrosani basin the Cerna Jiu fault has been reactivated by a left lateral
move-ment. The reactivation seems to coincide with the inversion of the Petrosani Basin due to a NW-SE trending stress field during the Sarmatian. After basin inversion during the Mal-vensian, coarse grained clastic material and crystalline con-glomerates accumulated in the eastern part of the Petrosani basin. This debris, reached from the flanks of the surroun-ding mountains, was deposited in high energy sedimentation systems and prove a steep relief within the orogen of the Southern Carpathians. The Apatite Fission Track studies should enlighten the evolution of the Petrosani basin during the formation of the Southern Carpathians. Vitrinite reflec-tions as well as a higher rank of the coal prove an increased heat flow after sedimentation. In case of a postsedimentatio-nal thermal overprint of the strata within the Petrosani basin, the Apatite grains should reveal the time of reset, which is suppose to coincide with the tectonical inversion and folding of the Oligocene sediments. In case of a low thermal altera-tion, the Apatite-Age-population method will give informa-tion about the uplift of the source area. The close distance between source area and deposition centre, combined with the strati graphic correlation of sedimentation and structural data allows it to confine the timing of internal deformation processes within the active orogen of the Southern Carpat-hians.
Reconstruction of Cretaceous rifts incorporated in the Outer West
Carpathian wedge by balancing
Michal Nemcok
1*,
Jan Nemcok
t ,Marek Wojtaszek
2,Livia Ludhova3, Nestor Oszczypko
2,William J. Sercombe4, Marek Cieszkowski2, Zbygniew Pau}S, Mike P. Coward
1&
Andrzej
SI~czka2
1 Department of Geology, Imperial College of Science,
Tech-nology and Medicine, Prince Consort Road, LondonSW72BP, UK 2Department of Geology, Jagiellonian University, Oleandry 2a, 30-063 Krak6w, Poland
3Department of Geology and Paleontology, Faculty of Na-tural Sciences, Comenius University, Mlynska dolina,
842 15 Bratislava, Slovakia
4Amoco Prod. Co., P.OBox. 4381, Houston, TX 77210, USA 5polish Geological Institute, Skrzat6w 1, 31-560 Krak6w, Poland
*present address: Inst. for Geology, University of Wuerz-burg, Pleicherwalll, D-970 70 Wuerzburg, Germany
Two balanced cross-sections are constructed through the Polish Outer Carpathians to restore Early Cretaceous rifts, the fill of which is incorporated into the Tertiary Carpathian accretionary wedge. The data indicate that the Early Creta-ceous rifting in the area of the Silesian Basin was followed by the Late Cretaceous-Paleocene basin inversion, Eocene pelagic deposition, and Oligocene accretionary prism
