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The present topography of the Făgăraş Mountains is a snapshot of the long-term evolution that brought about significant alterations
of the landscape, and especially of the relief, which has acquired different features depending on the intensity of the relationship
between the exogenous and endogenous agents. At present, relief shaping in the study area is controlled by the orographic
and climatic features. However, the climate of the high and middle-height mountains is the main cause that determines the
mechanism, the intensity and the spatial distribution of the shaping processes. The considerable height of the Făgăraş Mountains,
which exceeds 2500 m altitude is responsible for the vertical zonation of climate and vegetation which implicitly induce the
setting of the systems of relief modelling, too. 相似文献
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Crustal Assimilation as a Major Petrogenetic Process in the East Carpathian Neogene and Quaternary Continental Margin Arc, Romania 总被引:5,自引:0,他引:5
MASON PAUL R. D.; DOWNES HILARY; THIRLWALL MATTHEW F.; SEGHEDI IOAN; SZAKCS ALEXANDRU; LOWRY DAVID; MATTEY DAVID 《Journal of Petrology》1996,37(4):927-959
Miocene to Pleistocene calc-alkaline volcanism in the East Carpathianarc of Romania was related to the subduction of a small oceanbasin beneath the continental TiszaDacia microlate. Volcanicproducts are predominantly andesitic to dadtic in composition,with rare basalts and rhyodacites (51l71% SiO2; mg-number0.650.26) and have medium- to high-K calcalkaline andshoshonitic affinities. Mg, Cr and Ni are low in all rock-types,indicating the absence of primary erupted compositions. Detailedtrace element and Sr, Nd, Pb and 0 isotope data suggest thatmagmas were strongly crustally contaminated. Assimilation andfractional crystallization (AFC) calculations predict the consumptionof 535% local upper-crustal metasediments or sedimentsfrom the palaeo-accretionary wedge. Variations in the isotopiccomposition of the contaminants and parental magmas caused variationsin the mixing trajectories in different parts of the arc Themost primitive isotopic compositions are found in low-K dacitesof the northern Cdlimani volcanic centre and are interpretedas largely mantle derived. A second possible mantle reservoirof lower 149 Nd/144 Nd and lower 206 Pb/204 Pb is identifiedfrom back-arc basic calc-alkaline rocks in the south of thearc Both magmatic reservoirs have elevated isotopic characteristics,owing either to source bulk mixing (between depleted or enrichedasthenosphere and <1% average subducted local sediment) orlower-crustal contamination. KEY WORDS: Carpathians; assimilation; calc-alkaline; Sr-Nd-Pb-0 isotopes; laser flurination 相似文献
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