Classic skarn localities of Romania: Contact metamorphism and mineralization related to Late Cretaceous magmatism (original) (raw)

Day 4 2.13 Field stop 13-The skarn occurrence in Ogajul Cri$enilor, Oravija 2.14 Field stop 14-The skarns and banatites in Tiganilor Valley, Ciclova 2.15 Field stop 15-The porphyry copper ore deposit at Suvorov, Moldova Noua Acknowledgements 38 References Appendix 1. Minerals from occurrences visited during the field trip 45 B8i{a Bihor 45 Pietroasa 46 Magureaua Vajei 46 Ocna de Fier 46 Oravi(a-Ciclova 47 Moldova Noua 48 Appendix 2. Itinerary for 1MA2010 R05 Field trip 49 CLASSIC SKARN LOCALITIES OF ROMANIA • 6. The Moldavides (M)-are the outer most units of the Carpathian chain. They cover major parts of the East Carpathians Flysch Zone, excepting of the OD nappes. The component nappes are-from the inner to outer side: Convolute Flysch, Macla, Audia, Tarcau, Marginal Folds and Subcarpathian nappes. They consist of allochtonous bodies ranging Lower Cretaceous up to the Lower Miocene and are obducted over foreland areas. 7. The foredeep formations consist of Upper Miocene Pliocene-Lower Pleistocene molasses originating entirely in the inner Carpathian areas. They outborder the Carpathian chain to the east and south and cover parts of the neighbouring platforms. Sandulescu (1994) has summarized also the Mesozoic and Cenozoic magmatic activity which took place in the Carpathian area and in Apuseni Mts.: 1. Ophiolitic complexes developed between Middle Triassic and Upper Jurassic from the Tethysian oceanic crust (still preserved in the Transylvanides), and Jurassic ophiolites occurring in the Outer Dacidian paleorift (Severin Nappe of the OD). 2. Alkaline magmatism of Jurassic age developed in the extending margins of the Outer Dacidian paleorift. 3. Calc-alkaline magmatism developed during the compressive stages of the Carpathians, and in relation with subduction processes. Two main calc-alkaline periods were documented: a) "Banatites"predominantly intrusive, Upper Cretaceous-Paleocene, in the Southern Carpathians (Getic and Supragetic areas of the MD) and in the ID parts of Apuseni Mts., and b) Neogene volcanics, occurring in the Eastern Carpathians and Apuseni Mts. 4. Intracontinental basalts of Pliocene-Quaternary age (in Per?ani Mts. and Mure? Valley), in connection with deep (transcrustal) faults north-south direction over eastern Serbia (Timok and Ridanji-Krepoljin zones), and bends widely to the east, through the Srednogorie area, reaching the shores of the Black Sea (Fig. 3). The northern most occurrences are in Apuseni Mts., with the plutonic-volcanic Vladeasa massif (Istrate, 1978; §tefan, 1980; tefanetal.,1992)andnumeroussmallapexesanddykes,oftenrootedinlargeanddeepplutonicbodies(Andreietal.,1989),spreadoverlargeareasatCornijel−Borod,Gilau,Budureasa,Pietroasa,Bai?oara,ValeaSeaca,BaitaBihor,Brusturi,Cazane?ti,MagureauaVatei,(Fig.4)andintersectingpre−AlpinebasementandMesozoicformationsoftheMid−Cretaceousnappestructures(Berzaetal.,1998).Apartfromprevalentandesites,dacites,ignimbriticrhyolitesandbandedbiotite−bearingrhyolitesoftheVladeasa"taphrolite"(Giu?ca,1950),granodiorite−graniteintrusionsarepredominantamongotheroccurrencesintheApuseniMts.,withsubordinatequartzmonzodioritesandquartzdiorites(tefan et al., 1992) and numerous small apexes and dykes, often rooted in large and deep plutonic bodies (Andrei et al., 1989), spread over large areas at Cornijel-Borod, Gilau, Budureasa, Pietroasa, Bai?oara, Valea Seaca, Baita Bihor, Brusturi, Cazane?ti, Magureaua Vatei, (Fig. 4) and intersecting pre-Alpine basement and Mesozoic formations of the Mid-Cretaceous nappe structures (Berza et al., 1998). Apart from prevalent andesites, dacites, ignimbritic rhyolites and banded biotite-bearing rhyolites of the Vladeasa "taphrolite" (Giu?ca, 1950), granodiorite-granite intrusions are predominant among other occurrences in the Apuseni Mts., with subordinate quartz monzodiorites and quartz diorites (tefanetal.,1992)andnumeroussmallapexesanddykes,oftenrootedinlargeanddeepplutonicbodies(Andreietal.,1989),spreadoverlargeareasatCornijel−Borod,Gilau,Budureasa,Pietroasa,Bai?oara,ValeaSeaca,BaitaBihor,Brusturi,Cazane?ti,MagureauaVatei,(Fig.4)andintersectingpre−AlpinebasementandMesozoicformationsoftheMid−Cretaceousnappestructures(Berzaetal.,1998).Apartfromprevalentandesites,dacites,ignimbriticrhyolitesandbandedbiotite−bearingrhyolitesoftheVladeasa"taphrolite"(Giu?ca,1950),granodiorite−graniteintrusionsarepredominantamongotheroccurrencesintheApuseniMts.,withsubordinatequartzmonzodioritesandquartzdiorites(tefan et al., 1992). South of Mure? Valley, the belt continues with swarms of mainly intrusive, small magmatic bodies and larger intrusions, and with only sparse volcanic formations as those in the Cretaceous basins of the Poiana Rusca Mts. Other occurrences consisting of dioritic and granodioritic plutons and dyke swarms of andesites, dacites and rhyolites, accompanied by lamprophyric dykes are those at Tincova and 1-1.2 The regional extension of BMMB The BMMB represents a series of discontinuous magmatic and metallogenic districts that are discordant over the mid-Cretaceous nappe structures (Cioflica & Vlad, 1973; Ciobanu et al., 2002). The belt extends over approximately 900 km in length and around 30 to 70 km in width. It has a northeast to southwest trend over Apuseni Mts. and Southern Carpathians, it aligns to a TIMOK Volcanic and volcano-sedimentary rocks