Permian volcanic rocks from the Apuseni Mountains (Romania): Geochemistry and tectonic constraints

An Early Permian volcanic assemblage is well exposed in the central-western part of the Apuseni Mountains (Romania). The rocks are represented by rhyolites, basalts and subordinate andesites suggesting a bimodal volcanic activity that is intimately associated with a post-orogenic (Variscan) syn-sedimentary intra-basinal continental molasse sequences. The mafic and mafic-intermediate rocks belong to sub-alkaline tholeiitic series were separated in three groups (I–III) showing a high Th and Pb abundances, depletion in Nb, Ta and Sr, and slightly enriched in LREE patterns (La_N/Yb_N = 1.4–4.4). Isotopically, the rocks of Group I have the initial ratios ⁸⁷Sr/⁸⁶Sr_(i) = 0.709351–0.707112, ¹⁴³Nd/¹⁴⁴Nd_(i) = 0.512490–0.512588 and high positive ?_Nd270 values from 3.9 to 5.80; the rocks of Group II present for the initial ratios values ⁸⁷Sr/⁸⁶Sr_(i) = 0.709434–0.710092, ¹⁴³Nd/¹⁴⁴Nd_(i) = 0.512231–0.512210 and for ?_Nd270 the negative values from −1.17 to −1.56; the rocks of Group III display for the initial ratios the values ⁸⁷Sr/⁸⁶Sr_(i) = 0.710751–0.709448, ¹⁴³Nd/¹⁴⁴Nd_(i) = 0.512347–0.512411 and for ?_Nd270 the positive values from 1.64 to 2.35. The rocks resembling continental tholeiites, suggest a mantle origin and were further affected by fractionation and crustal contamination. In addition, the REE geochemistry (1 > Sm_N/Yb_N < 2.5; 0.9 > La_N/Sm_N < 2.5) suggests that these rocks were generated by high percentage partial melting of a metasomatized mantle in the garnet peridotite facies. The felsic rocks are enriched in Cs, Rb Th and U and depleted in Nb, Ta, Sr, Eu, and Ti. The REE fractionation patterns show a strong negative Eu anomaly (Eu/Eu* = 0.23–0.40). The felsic rocks show the initial ratios the values: ⁸⁷Sr/⁸⁶Sr_(i) = 0.704096–0.707805, ¹⁴³Nd/¹⁴⁴Nd_(i) = 0.512012–0.512021 and for ?_Nd270 the negative values from −5.27 to −5.44. They suggest to be generated within the lower crust during the emplacement of mantle-derived magmas that provided necessary heat to crustal partial melting.     

Comparative analysis of urban and industrial hierarchies of Romanian Towns in 1990

Urban and industrial hierarchies can be constructed as synthetic indicators of urbanisation and industrialisation at a particular moment in time. The beginning of 1990 is a significant time to undertake this exercise because of the collapse of the communist system and the start of a transition to a market economy. Industrialisation, the key to economic advance in general and to urbanisation in particular, is studied over four decades to bring out the concentration in large units (considered appopriate for economic efficiency) and the locational emphasis on the county (judget) administrative centres identified in 1968 ad the new territorial base for central planning. These centres, with their surrounding villages, experienced a demographic explosion. The paper examines the relations between the urban and industrial hierarchies at all levels with particular emphasis on the type of industry and the administrative functions.     

A rural development strategy for the Apuseni Mountains, Romania

The Apuseni Mountains, part of the Western Carpathians, are distinctive in cultural terms because of the highly dispersed settlement patterns that have developed on the high erosion surfaces where the Moti people cleared the forests to allow for an expansion of family farming in the eighteenth and nineteenth centuries. These small ‘crang’ settlements remain, but the population is declining in the face of limited employment opportunities and poor services. The question arises as to the most appropriate rural development strategy for the region, following the communist period which encouraged centralisation through the provision of housing and industry in key villages and new towns. The emphasis on private farming and the expansion of tourism could protect the inherited cultural landscape but money must be found to improve rural services. There is also a strong conservation movement which supports the establishment of a national park, but this could constrain development through controls on grazing and woodcutting. Hence the dialogue continues to find the best compromise and the concept of a ‘natural park’ is being discussed with such a reconciliation in mind. This revised version was published online in July 2006 with corrections to the Cover Date.     

Avalonian, Ganderian and East Cadomian terranes in South Carpathians, Romania, and Pan-African events recorded in their basement

New U-Pb geochronology is used to refine the provenance and evolution of northwest Gondwana Pan-African terranes preserved in the South Carpathians of Romania. The Dr?g?an terrane of Avalonian affinity, from the Danubian domain of the South Carpathians originated in the Panthalassa Ocean and accreted to the Amazonian part of Rodinia not much before 800 Ma, when the F?ge?el orthogneiss was intruded, at around 807–810 Ma. After this event no other Neoproterozoic magmatic pulse is known in the basement of the Dr?g?an terrane. The Ganderian type Lainici-P?iu? terrane from the same domain of the South Carpathians, recorded magmatic pulses at 782 Ma, 739 Ma, 708 Ma, 639 Ma, 600–587 Ma and 574–568 Ma. The East Cadomian Sebe?-Lotru terrane from the Getic domain of the South Carpathians recorded magmatic pulses at 817 Ma, 768 Ma, 685 Ma, 620 Ma, 584 Ma and 550 Ma. Post 630 Ma the northwestern Gondwana margin evolved as an active continental margin at least until 550 Ma, but the pre-630 Ma magmatism could be associated to some island arcs docked with different pre-Gondwanan continental fragments. Independent of the tectonic setting, the post 750 Ma orogens dated in the basement of the peri-Gondwanan terranes are discussed in the frame of the Cadomian orogens, as constituents of the Pan-African orogens in a broader sense. The detrital zircon may also record magmatic pulses from Pan-African orogens other than the Cadomian ones.